Title:

Robot arm mechanism

Document Type and Number:

United States Patent 7244091

Abstract:

Herein disclosed is a robot arm mechanism comprising a first arm link mechanism and a second arm link mechanism, a robot arm driving mechanism for driving the first arm link mechanism and the second arm link mechanism, and a link retaining mechanism for pivotably retaining the first arm link mechanism and the second arm link mechanism, in which a third arm link and a fourth arm link of the first arm link mechanism are kept forward in a first rotation direction, in which the first arm link mechanism and the second arm link mechanism are extended, thereby enabling to prevent the quadric crank chain constituting the robot arm mechanism from being flattened out while the first arm link mechanism and the second arm link mechanism are extended, and improving resistance to deformation, in comparison with the conventional robot arm mechanism.

Inventors:

Mori, Hiroki (Tsu, JP)
Watanabe, Tetsuya (Tsu, JP)
Okuno, Chohei (Ise, JP)

Plaque It!

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of application No. 10/308,122, filed Dec. 3, 2002 now U.S. Pat. No. 7,001,139, the disclosure of which is incorporated herein by reference. The applicants claim the benefit of the filing date of this application.

Claims:

What is claimed is:

1. A robot arm mechanism comprising: a first arm including first and second long parallel links each having a supporting end portion and a driving end portion and substantially in parallel relationship with each other, a first short parallel link intervening between the supporting end portions of said first and second long parallel links and a second short parallel link intervening between the driving end portions of said first and second long parallel links substantially in parallel relationship with said first short parallel link, said first long parallel link, said second long parallel link, said first short parallel link and said second short parallel link being pivotably connected with one another to collectively form a quadric crank chain; a second arm including a link having a handling end portion and a connecting end portion pivotably connected with said supporting end portion of said first long parallel link of said first arm; a link retaining mechanism having a reference line, said link retaining mechanism pivotably retaining said first arm and said second arm respectively and keeping a first angle substantially equal to a second angle, said first angle being an angle formed by a line passing through said driving end portion of said first long parallel link of said first arm with said reference line, said second angle being an angle formed by a line passing through said handling end portion of said second arm with said reference line; and a robot arm driving mechanism including a first driving shaft operative to rotate said driving end portion of said first long parallel link of said first arm around a rotation axis in any one of two rotation directions consisting of a first rotation direction in which said first arm and said second arm are extended, and a second rotation direction in which said first arm and said second arm are contracted, whereby said robot arm driving mechanism is operative to rotate said first long parallel link of said first arm around said rotation axis in said first rotation direction, and said second short parallel link of said first arm around said rotation axis in any one of two directions consisting of said first rotation direction and said second rotation direction while keeping said first and second short parallel links of said first arm forward in said first rotation direction in comparison with said first and second long parallel links of said first arm by maintaining said first angle less than a third angle formed by a line passing through said second short parallel link of said first arm with said reference line in said first rotation direction.

2. A robot arm mechanism as set forth in claim 1, in which said link retaining mechanism comprises: a first joint cross linkage including; a first short link having first and second end portions the former of which is fixedly connected with said link of said second arm, a first long link having first and second end portions and longer than said first short link of said first joint cross linkage, said first short and long links of said first joint cross linkage being pivotably connected with each other at said second end portion of said first short link of said first joint cross linkage and said first end portion of said first long link of said first joint cross linkage, a second short link having first and second end portions and substantially equal in length to said first short link of said first joint cross linkage, said first long link of said first joint cross linkage and said second short link of said first joint cross linkage being pivotably connected with each other at said second end portion of said first long link of said first joint cross linkage and said first end portion of said second short link of said first joint cross linkage, and a second long link having first and second end portions and substantially equal in length to said first long link of said first joint cross linkage, said second short and long links of said first joint cross linkage being pivotably connected with each other at said second end portion of said second short link of said first joint cross linkage and said first end portion of said second long link of said first joint cross linkage, said second long link of said first joint cross linkage and said first short link of said first joint cross linkage being pivotably connected with each other at said second end portion of said second long link of said first joint cross linkage and said first end portion of said first short link of said first joint cross linkage under the state that said second long link of said first joint cross linkage of said link retaining mechanism is crossed with said first long link of said first joint cross linkage, and said second long link of said first joint cross linkage being fixedly connected with said third arm link of said first arm, and a second joint cross linkage including; a first short link having first and second end portions, said first short link of said second joint cross linkage being substantially equal in length to said second long link of said first joint cross linkage and fixedly connected with said second long link of said first joint cross linkage, a first long link having first and second end portions and longer than said first short link of said second joint cross linkage, said first short and long links of said second joint cross linkage being pivotably connected with each other at said second end portion of said first short link of said second joint cross linkage and said first end portion of said first long link of said second joint cross linkage, said second short link of said first joint cross linkage being fixedly connected with said first long link of said second joint cross linkage, a second short link having first and second end portions and substantially equal in length to said first short link of said second joint cross linkage, said first long link of said second joint cross linkage and said second short link of said second joint cross linkage being pivotably connected with each other at said second end portion of said first long link of said second joint cross linkage and said first end portion of said second short link of said second joint cross linkage, and a second long link having first and second end portions and substantially equal in length to said first long link of said second joint cross linkage, said second short and long links of said second joint cross linkage being pivotably connected with each other at said second end portion of said second short link of said second joint cross linkage and said first end portion of said second long link of said second joint cross linkage, said second long link of said second joint cross linkage and said first short link of said second joint cross linkage being pivotably connected with each other at said second end portion of said second long link of said second joint cross linkage and said first end portion of said first short link of said second joint cross linkage under the state that said second long link of said second joint cross linkage is crossed with said first long link of said second joint cross linkage, said second long link of said second joint cross linkage being fixedly connected with said first long parallel link of said first arm.

3. A robot arm mechanism comprising: a first arm including a link having a supporting end portion and a driving end portion; a second arm including first and second long parallel links each having a connecting end portion and a handling end portion and substantially in parallel relationship with each other, a first short parallel link intervening between the connecting end portions of said first and second long parallel links and a second short parallel link intervening between the handling end portions of said first and second long parallel links substantially in parallel relationship with said first short parallel link, said first long parallel link, said second long parallel link, said first short parallel link and said second short parallel link being pivotably connected with one another to collectively form a quadric crank chain; a link retaining mechanism having a reference line, said link retaining mechanism pivotably retaining said supporting end portion of said first arm and said connecting end portion of one of said first and second long parallel links of said second arm respectively and keeping a first angle substantially equal to a second angle, said first angle being an angle formed by a line passing through said driving end portion of said link of said first arm with said reference line, said second angle being an angle formed by a line passing through said handling end portion of said first long parallel link of said second arm with said reference line; and a robot arm driving mechanism including a first driving shaft operative to rotate said driving end portion of said link of said first arm around a rotation axis in any one of two rotation directions consisting of a first rotation direction in which said first arm and said second arm are extended, and a second rotation direction in which said first arm and said second arm are contracted, whereby said robot arm driving mechanism is operative to rotate said link of said first arm around said rotation axis in said first rotation direction while keeping said first and second short parallel links of said second arm forward in said second rotation direction in comparison with said first and second long parallel links of said second arm by maintaining said second angle less than a third angle formed by a line passing through said second short parallel link of said second arm with said reference line in said first rotation direction.

4. A robot arm mechanism as set forth in claim 3, in which said link retaining mechanism includes a connecting link integrally formed with and angled to said first short parallel link of said second arm; and which further comprises: a second driving shaft driven to rotate around said rotation axis in any one of said first rotation direction and said second rotation direction; and a linkage intervening between said second driving shaft and said connecting link, and in which said first short parallel link of said second arm is driven by said driving shaft through said linkage and said connecting link with respect to said first long parallel link of said second arm in any one of said first rotation direction and said second rotation direction to have said first angle maintained less than said third angle when said first driving shaft and said second driving shaft are driven.

5. A robot arm mechanism as set forth in claim 3, in which said link retaining mechanism comprises: a first joint cross linkage including: a first short link having first and second end portions the former of which is fixedly connected with said first long parallel link of said second arm, a first long link having first and second end portions and longer than said first short link of said first joint cross linkage, said first short and long links of said first joint cross linkage being pivotably connected with each other at said second end portion of said first short link of said first joint cross linkage and said first end portion of said first long link of said first joint cross linkage, a second short link having first and second end portions and substantially equal in length to said first short link of said first joint cross linkage, said first long link of said first joint cross linkage and said second short link of said first joint cross linkage being pivotably connected with each other at said second end portion of said first long link of said first joint cross linkage and said first end portion of said second short link of said first joint cross linkage, and a second long link having first and second end portions and substantially equal in length to said first long link of said first joint cross linkage, said second short and long links of said first joint cross linkage being pivotably connected with each other at said second end portion of said second short link of said first joint cross linkage and said first end portion of said second long link of said first joint cross linkage, said second long link of said first joint cross linkage and said first short link of said first joint cross linkage being pivotably connected with each other at said second end portion of said second long link of said first joint cross linkage and said first end portion of said first short link of said first joint cross linkage under the state that said second long link of said first joint cross linkage is crossed with said first long link of said first joint cross linkage, and said second long link of said first joint cross linkage being fixedly connected with said first short parallel link of said second arm, and a second joint cross linkage including: a first short link having first and second end portions, said first short link of said second joint cross linkage being substantially equal in length to said second long link of said first joint cross linkage and integrally formed with said second long link of said first joint cross linkage, a first long link having first and second end portions and longer than said first short link of said second joint cross linkage, said first short and long links of said second joint cross linkage being pivotably connected with each other at said second end portion of said first short link of said second joint cross linkage and said first end portion of said first long link of said second joint cross linkage, and said second short link of said first joint cross linkage being fixedly connected with said first long link of said second joint cross linkage of said link retaining mechanism, a second short link having first and second end portions and substantially equal in length to said first short link of said second joint cross linkage, said first long link of said second joint cross linkage and said second short link of said second joint cross linkage being pivotably connected with each other at said second end portion of said first long link of said second joint cross linkage and said first end portion of said second short link of said second joint cross linkage, and a second long link having first and second end portions and substantially equal in length to said first long link of said second joint cross linkage, said second short and long links of said second joint cross linkage being pivotably connected with each other at said second end portion of said second short link of said second joint cross linkage and said first end portion of said second long link of said second joint cross linkage, said second long link of said second joint cross linkage and said first short link of said second joint cross linkage being pivotably connected with each other at said second end portion of said second long link of said second joint cross linkage and said first end portion of said first short link of said second joint cross linkage under the state that said second long link of said second joint cross linkage is crossed with said first long link of said second joint cross linkage, and said second long link of said second joint cross linkage being fixedly connected with said link of said first arm.

6. A robot arm mechanism, which comprises: a first arm having one and the other end portions; a second arm having one and the other end portions, said one end portion of said second arm being pivotably connected to said one end portion of said first arm so as to allow said first arm and said second arm to be extended and contracted along a reference line; and a link retaining mechanism intervening between said one end portions of said first arm and said second arm and keeping a first angle substantially equal to a second angle while said first arm and said second arm are extended and contracted, said first angle being an angle formed by a line passing through said the other end portion of said first arm with said reference line, said second angle being an angle formed by a line passing through said the other end portion said second arm with said reference line; said link retaining mechanism comprising: a first joint cross linkage including a pair of first joint links substantially equal in length to each other, one of said first joint links being fixedly connected with one of said first arm and said second arm, and a pair of second joint links substantially equal in length to each other and pivotally connected to said first joint links to be crossed with each other; and a second joint cross linkage including a pair of third joint links substantially equal in length to each other, one of said third joint links being fixedly connected with one of said second joint links of said first joint cross linkage, and a pair of fourth joint links substantially equal in length to each other, one of said fourth joint links being fixedly connected with the other of said first arm and said second arm, and the other of said fourth joint links being fixedly connected with the other of said first joint links of said first joint cross linkage; and in which at least one of two fixed joint links consisting of said one of said first joint links and said one of said fourth joint links is angled to a corresponding one of said first arm and said second arm.

7. A robot arm mechanism as set forth in claim 6, in which said first arm and said second arm are rotated with respect to said reference line in their respective extendable and contractible rotation directions to assume an extended position in which said first arm and said second arm are extended along said reference line and a contracted position in which said first arm and said second arm are contracted along said reference line, said one of said first joint links is rotated in said extendable rotation direction of said one of said first arm and said second arm when said first arm and said second arm are rotated from said contracted position to said extended position, said one of said fourth joint links is rotated in said extendable rotation direction of said the other of said first arm and said second arm when said first arm and said second arm are rotated from said contracted position to said extended position, and said at least one of said two fixed joint links is angled to said corresponding one of said first arm and said second arm in a corresponding one of said contractible rotation directions of said first arm and said second arm.

Description:

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a robot arm mechanism having arms contracted and extended, and more particularly to a robot arm mechanism incorporating an arm driving mechanism for driving the arms to assume its contracted and extended positions.

2. Description of the Related Art

Up until now, there have been proposed a wide variety of conventional robot arm mechanisms available in the process of producing semiconductors in which the robot arm mechanism is operated to have arms contracted and extended to handle works, i.e., objects to be treated. These objects may include works such as, for example, wafers and other precision parts that are to be transferred and then unloaded onto a work table by the robot arm mechanism.

One typical example of the conventional robot arm mechanism of this type is disclosed in, for example, Japanese Patent Laid-Open Publication No. 2000-208588. Such conventional robot arm mechanism 900 is shown in FIG. 20 as comprising a first arm link mechanism 910 , a second arm link mechanism 920 , a robot arm driving mechanism 930 , and a link retaining mechanism 940 .

The first arm link mechanism 910 consists of a quadric crank chain comprising a first arm link 911 , a second arm link 912 substantially in parallel relationship with the first arm link 911 , a third arm link 913 , and a fourth arm link 914 substantially in parallel relationship with the third arm link 913 . The second arm link mechanism 920 consists of a quadric crank chain comprising a first arm link 921 , a second arm link 922 substantially in parallel relationship with the first arm link 921 , a third arm link 923 , and a fourth arm link 924 substantially in parallel relationship with the third arm link 923 .

The first and second arm links 921 , 922 of the second arm link mechanism 920 are substantially equal in length to the first and second arm links 911 , 912 of the first arm link mechanism 910 , respectively. The third arm link 923 of the second arm link mechanism 920 is integrally formed with and fixedly connected with the third arm link 913 of the first arm link mechanism 910 .

The conventional robot arm mechanism 900 has a reference line 900 a , and further comprises a robot arm driving mechanism 930 . The robot arm driving mechanism 930 is adapted to drive the first arm link mechanism 910 so as to rotate the first arm link 911 and the second arm link 912 of the first arm link mechanism 910 with respect to the reference line 900 a.

The link retaining mechanism 940 consists of first and second joint cross linkages. The first joint cross linkage consists of a quadric crank chain comprising a first short link 941 , a second short link 942 substantially equal in length to the first short link 941 , a second long link 943 , and a first long link 944 substantially equal in length to the second long link 943 , wherein the first long link 944 of the first joint cross linkage of the link retaining mechanism 940 is crossed with the second long link 943 of the first joint cross linkage of the link retaining mechanism 940 . The second joint cross linkage consists of a quadric crank chain comprising a first short link 945 , a second short link 946 substantially equal in length to the first short link 945 , a second long link 947 , and a first long link 948 substantially equal in length to the second long link 947 , wherein the first long link 948 of the second joint cross linkage of the link retaining mechanism 940 is crossed with the second long link 947 of the second joint cross linkage of the link retaining mechanism 940 . Furthermore, the first short link 941 of the first joint cross linkage of the link retaining mechanism 940 is integrally formed with and fixedly connected with the first arm link 921 of the second arm link mechanism 920 , and the second long link 947 of the second joint cross linkage of the link retaining mechanism 940 is integrally formed with and fixedly connected with the first arm link 911 of the first arm link mechanism 910 .

The second long link 943 of the first joint cross linkage of the link retaining mechanism 940 is integrally formed with and fixedly connected with the third arm link 913 of the first arm link mechanism 910 , and the first short link 945 of the second joint cross linkage of the link retaining mechanism 940 substantially equal in length to the second long link 943 of the first joint cross linkage of the link retaining mechanism 940 , and integrally formed with and fixedly connected with the third arm link 923 of the second arm link mechanism 920 . The second short link 942 of the first joint cross linkage of the link retaining mechanism 940 integrally formed with and fixedly connected with the first long link 948 of the second joint cross linkage of the link retaining mechanism 940 .

The link retaining mechanism 940 thus constructed is adapted to pivotably retain the first arm link mechanism 910 and the second arm link mechanism 920 and keep a first angle θ 901 substantially equal to a second angle θ 902 , wherein the first angle θ 901 is an angle formed by the first arm link 911 of the first arm link mechanism 910 with the reference line 900 a , and the second angle θ 902 is an angle formed by the first arm link 921 of the second arm link mechanism 920 with the reference line 900 a.

The conventional robot arm mechanism 900 further comprises a robot arm member 951 having first and second end portions, and a handling member 952 for supporting and handling an object. The first end portion of the robot arm member 951 is integrally formed with and fixedly connected with the fourth arm link 924 of the second arm link mechanism 920 . The handling member 952 is connected with the second end portion of the robot arm member 951 .

The conventional robot arm mechanism 900 thus constructed makes it possible for the first arm link mechanism 910 and the second arm link mechanism 920 to be contracted and extended to assume its contracted and extended positions.

The conventional robot arm mechanism 900 thus constructed, however, encounters drawbacks resulting from the fact that the quadric crank chains constituting the first arm link mechanism 910 , the quadric crank chain constituting the second arm link mechanism 920 , and the quadric crank chain constituting the link retaining mechanism 940 may be easily flattened out, and accordingly vulnerable to deformation while the first arm link mechanism 910 and the second arm link mechanism 920 are extended to assume its extended position as shown in FIG. 20.

This means that the conventional robot arm mechanism 900 encounters a problem that the quadric crank chains constituting the first arm link mechanism 910 , the quadric crank chain of the second arm link mechanism 920 , and the link retaining mechanism 940 may be deformed due to, for example, a temperature change while the first arm link mechanism 910 and the second arm link mechanism 920 are extended, thereby making it difficult for the conventional robot arm mechanism 900 to accurately position the handling member 952 while the first arm link mechanism 910 and the second arm link mechanism 920 are extended, and accordingly aggravating the operating accuracy of the conventional robot arm mechanism 900 .

The conventional robot arm mechanism 900 encounters another problem that the quadric crank chains constituting the first arm link mechanism 910 , the quadric crank chain of the second arm link mechanism 920 , and the link retaining mechanism 940 may be deformed due to, for example, an external force exerted thereon while the first arm link mechanism 910 and the second arm link mechanism 920 are extended, thereby making it difficult for the conventional robot arm mechanism 900 to accurately position the handling member 952 independently of the external force exerted thereon while the first arm link mechanism 910 and the second arm link mechanism 920 are extended, and accordingly aggravating the operating accuracy of the conventional robot arm mechanism 900 .

The present invention is made with a view to overcoming the previously mentioned problems inherent to the conventional robot arm mechanism.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a robot arm mechanism which is resistant to deformation while the first arm link mechanism and the second arm link mechanism are extended, and accordingly enhancing the operating accuracy of the robot arm mechanism in comparison with the conventional robot arm mechanism.

In accordance with a first aspect of the present invention, there is provided a robot arm mechanism comprising: a first arm link mechanism consisting of a first quadric crank chain comprising a first arm link, a second arm link substantially in parallel relationship with the first arm link, a third arm link, and a fourth arm link substantially in parallel relationship with the third arm link; a second arm link mechanism consisting of a second quadric crank chain comprising a first arm link, a second arm link substantially in parallel relationship with the first arm link, a third arm link, and a fourth arm link substantially in parallel relationship with the third arm link, the second arm link mechanism is pivotably connected with the first arm link mechanism; a link retaining mechanism having a reference line, the link retaining mechanism pivotably retaining the first arm link mechanism and the second arm link mechanism respectively and keeping a first angle substantially equal to a second angle, the first angle being an angle formed by a line passing through the first arm link of the first arm link mechanism with the reference line, the second angle being an angle formed by a line passing through the first arm link of the second arm link mechanism with the reference line; a robot arm driving mechanism comprising; a first driving shaft operative to rotate the first arm link of the first arm link mechanism around a rotation axis in any one of two rotation directions consisting of a first rotation direction in which the first arm link mechanism and the second arm link mechanism are extended, and a second rotation direction in which the first arm link mechanism and the second arm link mechanism are contracted, and a second driving shaft operative to rotate the fourth arm link of the first arm link mechanism around the rotation axis in any one of two rotation directions consisting of the first rotation direction and the second rotation direction, a robot arm member having first and second end portions, the first end portion fixedly connected with the fourth arm link of the second arm link mechanism, and a handling member for supporting and handling an object, connected with the second end portion of the robot arm member. In the aforesaid robot arm mechanism, the robot arm driving mechanism is operative to rotate the first arm link of the first arm link mechanism around the rotation axis in the first rotation direction, and the fourth arm link of the first arm link mechanism around the rotation axis in any one of two directions consisting of the first rotation direction and the second rotation direction while maintaining the first angle formed by a line passing through the first arm link of the first arm link mechanism with the reference line less than a third angle formed by a line passing through the fourth arm link of the first arm link mechanism with the reference line in the first rotation direction. In the aforesaid robot arm mechanism according to the present invention, the third angle may be set to an angle so that the first arm link and the fourth arm link of the first arm link mechanism become substantially perpendicular to each other when the first arm link mechanism and the second arm link mechanism are extended to its their limits.

In accordance with a second aspect of the present invention, there is provided a robot arm mechanism comprising: a first arm link mechanism consisting of a first quadric crank chain comprising a first arm link, a second arm link substantially in parallel relationship with the first arm link, a third arm link, and a fourth arm link substantially in parallel relationship with the third arm link; a second arm link mechanism consisting of a second quadric crank chain comprising a first arm link, a second arm link substantially in parallel relationship with the first arm link, a third arm link, and a fourth arm link substantially in parallel relationship with the third arm link, the second arm link mechanism is pivotably connected with the first arm link mechanism; a link retaining mechanism having a reference line, the link retaining mechanism pivotably retaining the first arm link mechanism and the second arm link mechanism respectively and keeping a first angle substantially equal to a second angle, the first angle being an angle formed by a line passing through the second arm link of the first arm link mechanism with the reference line, the second angle being an angle formed by a line passing through the first arm link of the second arm link mechanism with the reference line; a robot arm member having first and second end portions, the first end portion fixedly connected with the fourth arm link of the second arm link mechanism; a handling member for supporting and handling an object, connected with the second end portion of the robot arm member; a robot arm driving mechanism comprising: a first driving shaft operative to rotate the first arm link of the first arm link mechanism around a rotation axis in any one of two rotation directions consisting of a first rotation direction in which the first arm link of the second arm link mechanism rotates in a rotation direction opposite to the first rotation direction, and the first arm link mechanism and the second arm link mechanism are extended, and a second rotation direction in which the first arm link of the second arm link mechanism rotates in a rotation direction opposite to the second rotation direction, and the first arm link mechanism and the second arm link mechanism are contracted, and a second driving shaft operative to rotate the fourth arm link of the first arm link mechanism around the rotation axis in any one of two rotation directions consisting of the first rotation direction and the second rotation direction. In the aforesaid robot arm mechanism, the robot arm driving mechanism is operative to rotate the first arm link of the first arm link mechanism around the rotation axis in the first rotation direction, and the fourth arm link of the first arm link mechanism around the rotation axis in any one of two directions consisting of the first rotation direction and the second rotation direction while maintaining the first angle formed by a line passing through the second arm link of the first arm link mechanism with the reference line less than a third angle formed by a line passing through the fourth arm link of the second arm link mechanism with the reference line in the rotation direction opposite to the first rotation direction. In the aforesaid robot arm mechanism according to the present invention, the third angle may be set to an angle so that the first arm link and the fourth arm link of the second arm link mechanism become substantially perpendicular to each other when the first arm link mechanism and the second arm link mechanism are extended to its their limits.

In accordance with a third aspect of the present invention, there is provided a robot arm mechanism comprising: a first arm link mechanism consisting of a first quadric crank chain comprising a first arm link, a second arm link substantially in parallel relationship with the first arm link, a third arm link, and a fourth arm link substantially in parallel relationship with the third arm link; a second arm link mechanism consisting of a second quadric crank chain comprising a first arm link, a second arm link substantially in parallel relationship with the first arm link, a third arm link, and a fourth arm link substantially in parallel relationship with the third arm link, the second arm link mechanism is pivotably connected with the first arm link mechanism; a link retaining mechanism having a reference line, the link retaining mechanism pivotably retaining the first arm link mechanism and the second arm link mechanism respectively and keeping a first angle substantially equal to a second angle, the first angle being an angle formed by a line passing through the first arm link of the first arm link mechanism with the reference line, the second angle being an angle formed by a line passing through the first arm link of the second arm link mechanism with the reference line; and a robot arm driving mechanism comprising; a first driving shaft operative to rotate the first arm link of the first arm link mechanism around a rotation axis in any one of two rotation directions consisting of a first rotation direction in which the first arm link mechanism and the second arm link mechanism are extended, and a second rotation direction in which the first arm link mechanism and the second arm link mechanism are contracted, and a second driving shaft operative to rotate the fourth arm link of the first arm link mechanism around the rotation axis in any one of two rotation directions consisting of the first rotation direction and the second rotation direction. In the aforesaid robot arm mechanism according to the present invention, the robot arm driving mechanism is operative to rotate the first arm link of the first arm link mechanism around the rotation axis in the first rotation direction, and the fourth arm link of the first arm link mechanism around the rotation axis in any one of two directions consisting of the first rotation direction and the second rotation direction while maintaining the first angle formed by a line passing through the first arm link of the first arm link mechanism with the reference line less than a third angle formed by a line passing through the fourth arm link of the first arm link mechanism with the reference line in the first rotation direction as well as maintaining the second angle formed by a line passing through the first arm link of the second arm link mechanism with the reference line less than a third angle formed by a line passing through the fourth arm link of the second arm link mechanism with the reference line in the rotation direction opposite to the first rotation direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features and advantages of the present invention will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a skeleton view of an extended position of a first preferred embodiment of the robot arm mechanism according to the present invention;

FIG. 2 is an enlarged fragmentary skeleton view of the robot arm mechanism shown in FIG. 1 to be used for explaining the principle of the robot arm mechanism according to the present invention;

FIG. 3 is a skeleton view of a contracted position of the robot arm mechanism shown in FIG. 1;

FIG. 4( a ) is an enlarged fragmentary skeleton view of one condition of a conventional robot arm mechanism to be used for explaining a drawback of the conventional robot arm mechanism;

FIG. 4( b ) is an enlarged fragmentary skeleton view of one condition of the robot arm mechanism shown in FIG. 1 to be used for explaining an advantage of the robot arm mechanism according to the present invention;

FIG. 5 is a skeleton view of an extended position of a modified first embodiment of the robot arm mechanism in which first and second arm links of a first arm link mechanism are longer than those of the robot arm mechanism shown in FIG. 1;

FIG. 6 is a skeleton view of an extended position of a second preferred embodiment of the robot arm mechanism according to the present invention;

FIG. 7 is an enlarged fragmentary skeleton view of the robot arm mechanism shown in FIG. 6 to be used for explaining the principle of the robot arm mechanism according to the present invention;

FIG. 8 is a skeleton view of a contracted position of the robot arm mechanism shown in FIG. 6;

FIG. 9( a ) is an enlarged fragmentary skeleton view of one condition of the conventional robot arm mechanism to be used for explaining a drawback of the conventional robot arm mechanism;

FIG. 9( b ) is an enlarged fragmentary skeleton view of one condition of the robot arm mechanism shown in FIG. 6 to be used for explaining an advantage of the robot arm mechanism according to the present invention;

FIG. 10 is a skeleton view of an extended position of the first embodiment of the robot arm mechanism in which first and second arm links of a first arm link mechanism are longer than those of the robot arm mechanism shown in FIG. 6;

FIG. 11 is a skeleton view of an extended position of a third preferred embodiment of the robot arm mechanism according to the present invention;

FIG. 12( a ) is an enlarged fragmentary skeleton view of one condition of the robot arm mechanism shown in FIG. 11 to be used for explaining a drawback of the conventional robot arm mechanism;

FIG. 12( b ) is an enlarged fragmentary skeleton view of one condition of the robot arm mechanism shown in FIG. 11 to be used for explaining the principle of the robot arm mechanism according to the present invention;

FIG. 13 is a skeleton view of a contracted position of the robot arm mechanism shown in FIG. 11;

FIG. 14( a ) is an enlarged fragmentary skeleton view of the condition of the robot arm mechanism shown in FIG. 12( a ) to be used for explaining a drawback of the conventional robot arm mechanism;

FIG. 14( b ) is an enlarged fragmentary skeleton view of the condition of the robot arm mechanism shown in FIG. 12( b ) to be used for explaining an advantage of the robot arm mechanism according to the present invention;

FIG. 15( a ) is an enlarged fragmentary skeleton view of another condition of the third embodiment of the robot arm mechanism wherein a link retaining mechanism is mounted on first and second arm link mechanism in a manner different from the robot arm mechanism shown in FIG. 12( b );

FIG. 15( b ) is an enlarged fragmentary skeleton view of another condition of the third embodiment of the robot arm mechanism wherein a link retaining mechanism is mounted on first and second arm link mechanism in a manner different from any one of the robot arm mechanisms shown in FIG. 12( b ) and FIG. 15( a );

FIG. 16( a ) is an enlarged fragmentary skeleton view of another condition of the third embodiment of the robot arm mechanism comprising a link retaining mechanism different from the one shown in FIG. 12( b );

FIG. 16( b ) is an enlarged fragmentary skeleton view of another condition of the third embodiment of the robot arm mechanism wherein a link retaining mechanism shown in FIG. 16( b ) is mounted in a conventional manner,

FIG. 17( a ) is an enlarged fragmentary skeleton view of another condition of the third embodiment of the robot arm mechanism comprising a link retaining mechanism different from the one shown in FIG. 12( b ) and 16 ( a );

FIG. 17( b ) is an enlarged fragmentary skeleton view of another condition of the third embodiment of the robot arm mechanism wherein a link retaining mechanism shown in FIG. 17( b ) is mounted in a conventional manner;

FIG. 18 is a skeleton view of an extended position of a fourth preferred embodiment of the robot arm mechanism according to the present invention;

FIG. 19 is a skeleton view of a contracted position of the robot arm mechanism shown in FIG. 18; and

FIG. 20 is a conventional robot arm mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Throughout the following detailed description, similar reference characters and numbers refer to similar elements in all figures of the drawings.

Referring to FIGS. 1 to 4 of the drawings, there is shown a first preferred embodiment of the robot arm mechanism 100 according to the present invention. The first embodiment of the robot arm mechanism 100 is shown in FIG. 1 as comprising a first arm link mechanism 110 , a second arm link mechanism 120 , a link retaining mechanism 140 , a robot arm driving mechanism 130 , a robot arm member 151 , and a handling member 152 .

The first arm link mechanism 110 consists of a first quadric crank chain comprising a first arm link 111 , a second arm link 112 , a third arm link 113 , and a fourth arm link 114 wherein the second arm link 112 is substantially in parallel relationship with the first arm link 111 and the fourth arm link 114 is substantially in parallel relationship with the third arm link 113 . The second arm link mechanism 120 consists of a second quadric crank chain comprising a first arm link 121 , a second arm link 122 , a third arm link 123 , and a fourth arm link 124 wherein the second arm link 122 is substantially in parallel relationship with the first arm link 121 and the fourth arm link 124 is substantially in parallel relationship with the third arm link 123 . The second arm link mechanism 120 is pivotably connected with the first arm link mechanism 110 .

The first arm link mechanism 110 and the second arm link mechanism 120 will be described in detail, hereinlater.

The first arm link 111 of the first arm link mechanism 110 has a driving end portion and a supporting end portion. The second arm link 112 , the third arm link 113 , and the fourth arm link 114 of the first arm link mechanism 110 respectively have first and second end portions. Similarly, the first arm link 121 of the second arm link mechanism 120 has a supporting end portion and a handling end portion. The second arm link 122 , the third arm link 123 , and the fourth arm link 124 of the second arm link mechanism 120 respectively have first and second end portions.

The first and third arm links 111 , 113 of the first arm link mechanism 110 are pivotably connected with each other at the supporting end portion of the first arm link 111 of the first arm link mechanism 110 and the first end portion of the third arm link 113 of the first arm link mechanism 110 . The third and second arm links 113 , 112 of the first arm link mechanism 110 are pivotably connected with each other at the second end portion of the third arm link 113 of the first arm link mechanism 110 and the first end portion of the second arm link 112 of the first arm link mechanism 110 . The second and fourth arm links 112 , 114 of the first arm link mechanism 110 are pivotably connected with each other at the second end portion of the second arm link 112 of the first arm link mechanism 110 and the first end portion of the fourth arm link 114 of the first arm link mechanism 110 . The fourth and first arm links 114 , 111 of the first arm link mechanism 110 are pivotably connected with each other at the second end portion of the fourth arm link 114 of the first arm link mechanism 110 and the driving end portion of the first arm link 111 of the first arm link mechanism 110 .

Similarly, the first and third arm links 121 , 123 of the second arm link mechanism 120 are pivotably connected with each other at the supporting end portion of the first arm link 121 of the second arm link mechanism 120 and the first end portion of the third arm link 123 of the second arm link mechanism 120 . The third and second arm links 123 , 122 of the second arm link mechanism 120 are pivotably connected with each other at the second end portion of the third arm link 123 of the second arm link mechanism 120 and the first end portion of the second arm link 122 of the second arm link mechanism 120 . The second and fourth arm links 122 , 124 of the second arm link mechanism 120 are pivotably connected with each other at the second end portion of the second arm link 122 of the second arm link mechanism 120 and the first end portion of the fourth arm link 124 of the second arm link mechanism 120 . The fourth and first arm links 124 , 121 of the second arm link mechanism 120 are pivotably connected with each other at the second end portion of the fourth arm link 124 of the second arm link mechanism 120 and the handling end portion of the first arm link 121 of the second arm link mechanism 120 . The third arm link 123 of the second arm link mechanism 120 is integrally formed with and fixedly connected with the third arm link 113 of the first arm link mechanism 110 .

The link retaining mechanism 140 has a reference line 100 a as shown in FIG. 1. The link retaining mechanism 140 is adapted to pivotably retain the first arm link mechanism 110 and the second arm link mechanism 120 respectively and keep a first angle substantially equal to a second angle wherein the first angle θ 101 is intended to mean an angle formed by a line passing through the first arm link 111 of the first arm link mechanism 110 with the reference line 100 a , and the second angle θ 102 is intended to mean an angle formed by a line passing through the first arm link 121 of the second arm link mechanism 120 with the reference line 100 a . The first angle θ 101 ranges from 0 to less than 180 degrees.

The link retaining mechanism 140 will be described in detail, hereinlater.

It is assumed that the link retaining mechanism 140 is adapted to pivotably retain the first arm link 111 of the first arm link mechanism 110 and the first arm link 121 of the second arm link mechanism 120 respectively at the supporting end portions of the first arm link 111 of the first arm link mechanism 110 and the first arm link 121 of the second arm link mechanism 120 and keep the first angle θ 101 substantially equal to the second angle θ 102 .

The link retaining mechanism 140 comprises a first joint cross linkage. The first joint cross linkage is a quadric crank chain and includes a first short link 141 , a first long link 144 , a second short link 142 , and a second long link 143 . The first short link 141 has first and second end portions. The first long link 144 has first and second end portions and is longer than the first short link 141 of the first joint cross linkage of the link retaining mechanism 140 . The first short and long links 141 , 144 of the first joint cross linkage of the link retaining mechanism 140 are pivotably connected with each other at the second end portion of the first short link 141 of the first joint cross linkage of the link retaining mechanism 140 and the first end portion of the first long link 144 of the first joint cross linkage of the link retaining mechanism 140 . The second short link 142 has first and second end portions and is substantially equal in length to the first short link 141 of the first joint cross linkage of the link retaining mechanism 140 . The first long link 144 of the first joint cross linkage of the link retaining mechanism 140 and the second short link 142 of the first joint cross linkage of the link retaining mechanism 140 are pivotably connected with each other at the second end portion of the first long link 144 of the first joint cross linkage of the link retaining mechanism 140 and the first end portion of the second short link 142 of the first joint cross linkage of the link retaining mechanism 140 . The second long link 143 has first and second end portions and is substantially equal in length to the first long link 144 of the first joint cross linkage of the link retaining mechanism 140 . The second short and long links 142 , 143 of the first joint cross linkage of the link retaining mechanism 140 are pivotably connected with each other at the second end portion of the second short link 142 of the first joint cross linkage of the link retaining mechanism 140 and the first end portion of the second long link 143 of the first joint cross linkage of the link retaining mechanism 140 . The second long link 143 of the first joint cross linkage of the link retaining mechanism 140 and the first short link 141 of the first joint cross linkage of the link retaining mechanism 140 are pivotably connected with each other at the second end portion of the second long link 143 of the first joint cross linkage of the link retaining mechanism 140 and the first end portion of the first short link 141 of the first joint cross linkage of the link retaining mechanism 140 under the state that the second long link 143 of the first joint cross linkage of the link retaining mechanism 140 is crossed with the first long link 144 of the first joint cross linkage of the link retaining mechanism 140 .

The first short link 141 of the first joint cross linkage of the link retaining mechanism 140 is integrally formed with and fixedly connected with the first arm link 121 of the second arm link mechanism 120 . The second long link 143 of the first joint cross linkage of the link retaining mechanism 140 is integrally formed with and fixedly connected with the third arm link 113 of the first arm link mechanism 110 and the third arm link 123 of the second arm link mechanism 120 .

The link retaining mechanism 140 further comprises a second joint cross linkage. The second joint cross linkage is a quadric crank chain, and includes a first short link 145 , a first long link 148 , a second short link 146 , and a second long link 147 . The first short link 145 has first and second end portions. The first short link 145 of the second joint cross linkage of the link retaining mechanism 140 is substantially equal in length to the second long link 143 of the first joint cross linkage of the link retaining mechanism 140 , and integrally formed with and fixedly connected with the third arm link 113 of the first arm link mechanism 110 and the third arm link 123 of the second arm link mechanism 120 . The first long link 148 has first and second end portions and is longer than the first short link 145 of the second joint cross linkage of the link retaining mechanism 140 . The first short and long links 145 , 148 of the second joint cross linkage of the link retaining mechanism 140 are pivotably connected with each other at the second end portion of the first short link 145 of the second joint cross linkage of the link retaining mechanism 140 and the first end portion of the first long link 148 of the second joint cross linkage of the link retaining mechanism 140 . The second short link 142 of the first joint cross linkage of the link retaining mechanism 140 are integrally formed with and fixedly connected with the first long link 148 of the second joint cross linkage of the link retaining mechanism 140 . The second short link 146 has first and second end portions and is substantially equal in length to the first short link 145 of the second joint cross linkage of the link retaining mechanism 140 . The first long link 148 of the second joint cross linkage of the link retaining mechanism 140 and the second short link 146 of the second joint cross linkage of the link retaining mechanism 140 are pivotably connected with each other at the second end portion of the first long link 148 of the second joint cross linkage of the link retaining mechanism 140 and the first end portion of the second short link 146 of the second joint cross linkage of the link retaining mechanism 140 . The second long link 147 has first and second end portions and is substantially equal in length to the first long link 148 of the second joint cross linkage of the link retaining mechanism 140 . The second short and long links 146 , 147 of the second joint cross linkage of the link retaining mechanism 140 are pivotably connected with each other at the second end portion of the second short link 146 of the second joint cross linkage of the link retaining mechanism 140 and the first end portion of the second long link 147 of the second joint cross linkage of the link retaining mechanism 140 . The second long link 147 of the second joint cross linkage of the link retaining mechanism 140 and the first short link 145 of the second joint cross linkage of the link retaining mechanism 140 are pivotably connected with each other at the second end portion of the second long link 147 of the second joint cross linkage of the link retaining mechanism 140 and the first end portion of the first short link 145 of the second joint cross linkage of the link retaining mechanism 140 under the state that the second long link 147 of the second joint cross linkage of the link retaining mechanism 140 is crossed with the first long link 148 of the second joint cross linkage of the link retaining mechanism 140 . The second long link 147 of the second joint cross linkage of the link retaining mechanism 140 is integrally formed with and fixedly connected with the first arm link 111 of the first arm link mechanism 110 .

The robot arm driving mechanism 130 comprises a first driving shaft 131 and a second driving shaft 132 . The first driving shaft 131 is integrally formed with and fixedly connected with and adapted to rotate the first arm link 111 of the first arm link mechanism 110 around a rotation axis in any one of two rotation directions consisting of a first rotation direction 130 a in which the first arm link mechanism 110 and the second arm link mechanism 120 are extended, and a second rotation direction 130 b in which the first arm link mechanism 110 and the second arm link mechanism 120 are contracted. The second driving shaft 132 is integrally formed with and fixedly connected with and adapted to rotate the fourth arm link 114 of the first arm link mechanism 110 around the rotation axis in any one of two rotation directions consisting of the first rotation direction 130 a and the second rotation direction 130 b.

The robot arm member 151 has first and second end portions. The first end portion of the robot arm member 151 is integrally formed with and fixedly connected with one of the second arm link 122 and the fourth arm link 124 of the second arm link mechanism 120 .

The handling member 152 is fixedly connected with the second end portion of the robot arm member 151 , and adapted to support and handle an object. According to the present invention, the handling member 152 may be adapted to, for example, grip the object.

Furthermore, the robot arm driving mechanism 130 is adapted to rotate the first arm link 111 of the first arm link mechanism 110 around the rotation axis the first rotation direction 130 a , and the fourth arm link 114 of the first arm link mechanism 110 around the rotation axis in any one of two directions consisting of the first rotation direction 130 a and the second rotation direction 130 b while maintaining the first angle θ 101 formed by a line 111 a passing through the first arm link 111 of the first arm link mechanism 110 with the reference line 100 a less than a third angle θ 103 formed by a line 114 a passing through the fourth arm link 114 of the first arm link mechanism 110 with the reference line 100 a in the first rotation direction 130 a as best shown in FIG. 2. The third angle θ 103 ranges from 0 to less than 180 degrees.

The operation of the first embodiment of the robot arm mechanism 100 will be described, hereinlater.

As shown in FIG. 2, the first driving shaft 131 is operated to rotate the first arm link 111 of the first arm link mechanism 110 around the rotation axis to change the first angle θ 101 . The first driving shaft 131 is operated to rotate the first arm link 111 of the first arm link mechanism 110 around the rotation axis in, for example, the first rotation direction 130 a , the first arm link mechanism 110 and the second arm link mechanism 120 are then operated to be extended. The first driving shaft 131 , on the other hand, is operated to rotate the first arm link 111 of the first arm link mechanism 110 around the rotation axis in, for example, the second rotation direction 130 b , the first arm link mechanism 110 and the second arm link mechanism 120 are then operated to be contracted. This means that the first driving shaft 131 may rotate the first arm link 111 of the first arm link mechanism 110 around the rotation axis in the first rotation direction 130 a until the first arm link mechanism 110 and the second arm link mechanism 120 assumes an extended position as shown in FIG. 1, and the first driving shaft 131 may rotate the first arm link 111 of the first arm link mechanism 110 around the rotation axis in the second rotation direction 130 b until the first arm link mechanism 110 and the second arm link mechanism 120 assumes a contracted position as shown in FIG. 3. Alternatively, the first arm link mechanism 110 and the second arm link mechanism 120 may further be contracted beyond the contracted position shown in FIG. 3.

The first driving shaft 131 and the second driving shaft 132 may respectively rotate the first arm link 111 of the first arm link mechanism 110 and the fourth arm link 114 of the first arm link mechanism 110 around the rotation axis in the same rotation direction, for example, the first rotation direction 130 a or the second rotation direction 130 b for the same amount of rotation angle, the robot arm mechanism 100 as a whole, including the first arm link mechanism 110 and the second arm link mechanism 120 , is then rotated around the rotation axis in the rotation direction.

As described hereinbefore, the robot arm driving mechanism 130 is operated to rotate the first arm link 111 of the first arm link mechanism 110 around the rotation axis in the first rotation direction 130 a , in which the first arm link mechanism 110 and the second arm link mechanism 120 are extended, and the fourth arm link 114 of the first arm link mechanism 110 around the rotation axis in any one of two directions consisting of the first rotation direction 130 a and the second rotation direction 130 b while maintaining the first angle θ 101 formed by a line 111 a passing through the first arm link 111 of the first arm link mechanism 110 with the reference line 100 a less than a third angle θ 103 formed by a line 114 a passing through the fourth arm link 114 of the first arm link mechanism 110 with the reference line 100 a in the first rotation direction 130 a as best shown in FIG. 2. This means that the first embodiment of the robot arm mechanism 100 , in which the third angle θ 103 formed by the line 114 a passing through the fourth arm link 114 of the first arm link mechanism 110 with the reference line 100 a in the first rotation direction 130 a is maintained grater than the first angle θ 101 formed by the line 111 a passing through the first arm link 111 of the first arm link mechanism 110 with the reference line 100 a (see FIG. 2) while the first arm link mechanism 110 and the second arm link mechanism 120 are extended, can prevent the quadric crank chain constituting the first arm link mechanism 110 from being flattened out while the first arm link mechanism 110 and the second arm link mechanism 120 are extended, thereby improving resistance to deformation while the first arm link mechanism 110 and the second arm link mechanism 120 are extended as shown in FIG. 1, in comparison with the conventional robot arm mechanism 900 shown in FIG. 20 for the reason described hereinlater.

The quadric crank chain constituting the first arm link mechanism 110 of the first embodiment of the robot arm mechanism 100 does not take on a flattened out condition, in which the third angle θ 103 formed by a line 114 a passing through the fourth arm link 114 of the first arm link mechanism 110 with the reference line 100 a in the first rotation direction 130 a is, for example, substantially zero degree as shown in FIG. 4( a ), which the quadric crank chain constituting the first arm link mechanism 910 of the conventional robot arm mechanism 900 takes on when the conventional robot arm mechanism 900 assumes, for example, an extended position shown in FIG. 20, because of the fact that the robot arm driving mechanism 130 is operated to rotate the first arm link 111 of the first arm link mechanism 110 and the fourth arm link 114 of the first arm link mechanism 110 around the rotation axis while maintaining the first angle θ 101 formed by a line 11 a passing through the first arm link 111 of the first arm link mechanism 110 with the reference line 100 a less than a third angle θ 103 formed by a line 114 a passing through the fourth arm link 114 of the first arm link mechanism 110 with the reference line 100 a in the first rotation direction 130 a as best shown in FIG. 4( b ), thereby preventing the first quadric crank chain constituting the first arm link mechanism 110 from being flattened out while the first arm link mechanism 110 and the second arm link mechanism 120 are extended. This means that the third arm link 113 and the fourth arm link 114 of the first arm link mechanism 110 are kept forward in the first rotation direction 130 a with respect to the reference line 100 a in comparison with the third arm link 913 and the fourth arm link 914 of the first arm link mechanism 910 of the conventional robot arm mechanism 900 .

A force F 101 , for example, substantially perpendicular to the reference line 100 a is exerted on the quadric crank chain constituting the first arm link mechanism 110 of the robot arm mechanism 100 on the supposition that the quadric crank chain constituting the first arm link mechanism 110 of the robot arm mechanism 100 should take on a flattened out condition, which the quadric crank chain constituting the first arm link mechanism 910 of the conventional robot arm mechanism 900 takes on when the conventional robot arm mechanism 900 assumes, for example, an extended position as shown in FIG. 20, the force F 101 exerted on the first arm link mechanism 110 would be resolved into a component force F 102 exerted on the first arm link 111 of the first arm link mechanism 110 and a component force F 103 exerted on the third arm link 113 of the first arm link mechanism 110 as shown in FIG. 4( a ). The same force F 101 substantially perpendicular to the reference line 100 a , on the other hand, is exerted on the quadric crank chain constituting the first arm link mechanism 110 of the first embodiment of the robot arm mechanism 100 , the force F 101 exerted on the first arm link mechanism 110 can be resolved into a component force F 104 exerted on the first arm link 111 of the first arm link mechanism 110 , which is smaller than the component force F 102 , and a component force F 105 exerted on the third arm link 113 of the first arm link mechanism 110 , which is smaller than the component force F 103 , as shown in FIG. 4( b ).

While it has been described in the above that the force F 101 substantially perpendicular to the reference line 100 a and exerted on the quadric crank chain constituting the first arm link mechanism 110 of the robot arm mechanism 100 are resolved into component forces F 104 , F 105 respectively exerted on the first arm link 111 of the first arm link mechanism 110 and the third arm link 113 of the first arm link mechanism 110 , which are reduced in comparison with component forces F 102 , F 103 to be resolved from the force F 101 exerted on the first arm link mechanism 910 and respectively exerted on the third arm link 911 of the first arm link mechanism 910 and the third arm link 913 of the first arm link mechanism 910 of the conventional robot arm mechanism 900 , a force parallel with the reference line 100 a exerted on the quadric crank chain constituting the first arm link mechanism 110 of the robot arm mechanism 100 may be resolved into component forces exerted on respective arm links constituting the first arm link mechanism 110 , which are reduced in comparison with component forces to be resolved from the same force exerted on the first arm link mechanism 910 and exerted on respective arm links constituting the first arm link mechanism 910 of the conventional robot arm mechanism 900 in a similar manner as described above.

From the foregoing descriptions, it is to be understood that the first arm link mechanism 110 of the robot arm mechanism 100 according to the present invention, in which component forces resolved from a force exerted on the first arm link mechanism 110 and exerted on respective arm links constituting the first arm link mechanism 110 are reduced in comparison with component forces to be resolved from the same force exerted on the first arm link mechanism 910 and exerted on respective arm links of the first arm link mechanism 910 of the conventional robot arm mechanism 900 , can be resistant to deformation due to an external force while the first arm link mechanism 110 and the second arm link mechanism 120 are extended, and accordingly enhance the operating accuracy of the robot arm mechanism 100 in comparison with the conventional robot arm mechanism 900 .

Furthermore, the first arm link mechanism 110 of the robot arm mechanism 100 according to the present invention, in which the third arm link 113 and the fourth arm link 114 of the first arm link mechanism 110 are kept forward in the first rotation direction 130 a with respect to the reference line 100 a in comparison with the third arm link 913 and the fourth arm link 914 of the first arm link mechanism 910 of the conventional robot arm mechanism 900 , is resistant to deformation in comparison with the third arm link 913 and the fourth arm link 914 of the first arm link mechanism 910 of the conventional robot arm mechanism 900 because of the fact that the dimensional errors of arm links constituting the first arm link mechanism 110 occurred due to, for example, a temperature change, machining error and assembly error, are spread through the arm links constituting the first arm link mechanism 110 in directions except for directions substantially perpendicular to and parallel with the reference line 100 a , thereby enhancing the operating accuracy of the handling member 152 of the robot arm mechanism 100 while the first robot arm link mechanism 120 and the second robot arm link mechanism 120 are expanded.

According to the present invention, the third angle θ 103 formed by a line 114 a passing through the fourth arm link 114 of the first arm link mechanism 110 with the reference line 100 a in the first rotation direction 130 a may be any angle greater than the first angle θ 101 formed by a line 111 a passing through the first arm link 111 of the first arm link mechanism 110 with the reference line 100 a as shown in FIG. 2. The third angle θ 103 formed by a line 114 a passing through the fourth arm link 114 of the first arm link mechanism 110 with the reference line 100 a in the first rotation direction 130 a may be set to, for example, an angle so that the first arm link 111 and the fourth arm link 114 of the first arm link mechanism 110 become substantially perpendicular to each other when the first arm link mechanism 110 and the second arm link mechanism 120 are extended to its their limits.

The longer an arm link is, the smaller the machining error of the arm link with respect to the total length of the arm link. In order to attain the object of the present invention, the third arm link 113 and the fourth arm link 114 of the first arm link mechanism 110 may be respectively replaced with a fifth arm link 115 longer than the third arm link 113 and a sixth arm link 116 substantially in parallel relationship with the fifth arm link 115 and longer than the fourth arm link 114 of the first arm link mechanism 110 of the first embodiment of the robot arm mechanism 100 as shown in FIG. 5.

Referring to FIG. 5 of the drawings, there is shown a modified first embodiment of the robot arm mechanism 100 . The modified first embodiment of the robot arm mechanism 100 is similar to the first embodiment of the robot arm mechanism 100 except for the fact that the third arm link 113 and the fourth arm link 114 of the first arm link mechanism 110 are respectively replaced with the fifth arm link 115 and the sixth arm link 116 . The modified first embodiment of the robot arm mechanism 100 , in which the third arm link 113 and the fourth arm link 114 of the first arm link mechanism 110 are respectively replaced with the fifth arm link 115 and the sixth arm link 116 , is resistant to deformation due to the machining error and makes it possible for the handling member 152 to linearly move along the reference line 100 a while the first arm link mechanism 110 and the second arm link mechanism 120 are expanded, in comparison with the robot arm mechanism 100 shown in FIG. 1,

Furthermore, the modified first embodiment of the robot arm mechanism 100 comprising the fifth arm link 115 and the sixth arm link 116 substantially in parallel relationship with each other, and respectively longer than the third arm link 113 and the fourth arm link 114 in place of the third arm link 113 and the fourth arm link 114 , may have arm links constituting the first arm link mechanism 110 thicker than those of the first embodiment of the robot arm mechanism 100 shown in FIG. 1, thereby enhancing the rigidity of the first arm link mechanism 110 and the robot arm driving mechanism 130 constituting modified first embodiment of the robot arm mechanism 100 .

While it has been described in the above that the link retaining mechanism 140 consists of two quadric crank chains, the link retaining mechanism 140 may be constituted by any mechanism such as, for example, synchronous gears, pulley and belt mechanism publicly known in the art, as long as the link retaining mechanism 140 is operative to pivotably retain the first arm link mechanism 110 and the second arm link mechanism 120 respectively and keep the first angle θ 101 formed by a line passing through the first arm link 111 of the first arm link mechanism 110 with the reference line 100 a equal to the second angle θ 102 formed by a line passing through the first arm link 121 of the second arm link mechanism 120 with the reference line 100 a.

While it has been described in the above that the handling member 152 is fixedly connected with the second end portion of the robot arm member 151 , the handling member 152 may be fixedly connected with the second arm link mechanism 120 without the handling member 152 in a manner that the handling member 152 is fixedly connected with, for example, one of the arm links constituting the second arm link mechanism 120 such as, for example, the first, second, and fourth arm link 121 , 122 , and 124 .

From the foregoing description, it is to be understood that the first embodiment of the robot arm mechanism 100 according to the present invention is resistant to deformation while the first arm link mechanism 110 and the second arm link mechanism 120 are extended, and accordingly enhancing the operating accuracy of the robot arm mechanism 100 in comparison with the conventional robot arm mechanism.

Referring to FIGS. 6 to 10 of the drawings, there is shown a second preferred embodiment of the robot arm mechanism 200 according to the present invention.

The second embodiment of the robot arm mechanism 200 is shown in FIG. 6 as comprising a first arm link mechanism 210 , a second arm link mechanism 220 , a robot arm driving mechanism 230 , a link retaining mechanism 240 , a robot arm member 251 , and a handling member 252 .

The first arm link mechanism 210 consists of a first quadric crank chain comprising a first arm link 211 , a second arm link 212 , a third arm link 213 , and a fourth arm link 214 . The second arm link 212 is substantially in parallel relationship with the first arm link 211 . The fourth arm link 214 is substantially in parallel relationship with the third arm link 213 .

The second arm link mechanism 220 consists of a second quadric crank chain comprising a first arm link 221 , a second arm link 222 substantially in parallel relationship with the first arm link 221 , a third arm link 223 , and a fourth arm link 224 substantially in parallel relationship with the third arm link 223 , the second arm link mechanism 220 is pivotably connected with the first arm link mechanism 210 . The second arm link 222 is substantially in parallel relationship with the first arm link 221 . The fourth arm link 224 is substantially in parallel relationship with the third arm link 223 . The second arm link mechanism 220 is pivotably connected with the first arm link mechanism 210 .

The first arm link mechanism 210 and the second arm link mechanism 220 will be described in detail, hereinlater.

The first arm link 211 of the first arm link mechanism 210 has a driving end portion and a supporting end portion. The second arm link 212 , the third arm link 213 , and the fourth arm link 214 of the first arm link mechanism 210 respectively have first and second end portions. The first and third arm links 211 , 213 of the first arm link mechanism 210 are pivotably connected with each other at the supporting end portion of the first arm link 211 of the first arm link mechanism 210 and the first end portion of the third arm link 213 of the first arm link mechanism 210 . The third and second arm links 213 , 212 of the first arm link mechanism 210 are pivotably connected with each other at the second end portion of the third arm link 213 of the first arm link mechanism 210 and the first end portion of the second arm link 212 of the first arm link mechanism 210 . The second and fourth arm links 212 , 214 of the first arm link mechanism 210 are pivotably connected with each other at the second end portion of the second arm link 212 of the first arm link mechanism 210 and the first end portion of the fourth arm link 214 of the first arm link mechanism 210 . The fourth and first arm links 214 , 211 of the first arm link mechanism 210 are pivotably connected with each other at the second end portion of the fourth arm link 214 of the first arm link mechanism 210 and the driving end portion of the first arm link 211 of the first arm link mechanism 210 .

Similarly, the first arm link 221 of the second arm link mechanism 220 has a supporting end portion and a handling end portion. The second arm link 222 , the third arm link 223 , and the fourth arm link 224 of the second arm link mechanism 220 respectively have first and second end portions. The first and third arm links 221 , 223 of the second arm link mechanism 220 are pivotably connected with each other at the supporting end portion of the first arm link 221 of the second arm link mechanism 220 and the first end portion of the third arm link 223 of the second arm link mechanism 220 . The third and second arm links 223 , 222 of the second arm link mechanism 220 are pivotably connected with each other at the second end portion of the third arm link 223 of the second arm link mechanism 220 and the first end portion of the second arm link 222 of the second arm link mechanism 220 . The second and fourth arm links 222 , 224 of the second arm link mechanism 220 are pivotably connected with each other at the second end portion of the second arm link 222 of the second arm link mechanism 220 and the first end portion of the fourth arm link 224 of the second arm link mechanism 220 . The fourth and first arm links 224 , 221 of the second arm link mechanism 220 are pivotably connected with each other at the second end portion of the fourth arm link 224 of the second arm link mechanism 220 and the handling end portion of the first arm link 221 of the second arm link mechanism 220 . The third arm link 223 of the second arm link mechanism 220 is integrally formed with and fixedly connected with the third arm link 213 of the first arm link mechanism 210 .

The link retaining mechanism 240 has a reference line 200 a as shown in FIG. 2. The link retaining mechanism 240 is adapted to pivotably retain the first arm link mechanism 210 and the second arm link mechanism 220 respectively and keep a first angle substantially equal to a second angle, wherein the first angle θ 201 is intended to mean an angle formed by a line passing through the second arm link 212 of the first arm link mechanism 210 with the reference line 200 a , and the second angle θ 202 is intended to mean an angle formed by a line passing through the first arm link 221 of the second arm link mechanism 220 with the reference line 200 a . The first angle θ 201 ranges from 0 to less than 180 degrees.

The link retaining mechanism 240 will be described in detail, hereinlater.

It is assumed that the link retaining mechanism 240 is operative to pivotably retain the first arm link 211 of the first arm link mechanism 210 and the first arm link 221 of the second arm link mechanism 220 respectively at the supporting end portions of the first arm link 211 of the first arm link mechanism 210 and the first arm link 221 of the second arm link mechanism 220 and keep the first angle substantially equal to the second angle.

The link retaining mechanism 240 comprises a first joint cross linkage. The first joint cross linkage is a quadric crank chain and includes a first short link 241 , a first long link 244 , a second short link 242 , and a second long link 243 .

The first short link 241 has first and second end portions. The first long link 244 has first and second end portions and longer than the first short link 241 of the first joint cross linkage of the link retaining mechanism 240 . The first short and long links 241 , 244 of the first joint cross linkage of the link retaining mechanism 240 are pivotably connected with each other at the second end portion of the first short link 241 of the first joint cross linkage of the link retaining mechanism 240 and the first end portion of the first long link 244 of the first joint cross linkage of the link retaining mechanism 240 . The second short link 242 has first and second end portions and substantially equal in length to the first short link 241 of the first joint cross linkage of the link retaining mechanism 240 . The first long link 244 of the first joint cross linkage of the link retaining mechanism 240 and the second short link 242 of the first joint cross linkage of the link retaining mechanism 240 are pivotably connected with each other at the second end portion of the first long link 244 of the first joint cross linkage of the link retaining mechanism 240 and the first end portion of the second short link 242 of the first joint cross linkage of the link retaining mechanism 240 . The second long link 243 has first and second end portions and substantially equal in length to the first long link 244 of the first joint cross linkage of the link retaining mechanism 240 . The second short and long links 242 , 243 of the first joint cross linkage of the link retaining mechanism 240 are pivotably connected with each other at the second end portion of the second short link 242 of the first joint cross linkage of the link retaining mechanism 240 and the first end portion of the second long link 243 of the first joint cross linkage of the link retaining mechanism 240 . The second long link 243 of the first joint cross linkage of the link retaining mechanism 240 and the first short link 241 of the first joint cross linkage of the link retaining mechanism 240 are pivotably connected with each other at the second end portion of the second long link 243 of the first joint cross linkage of the link retaining mechanism 240 and the first end portion of the first short link 241 of the first joint cross linkage of the link retaining mechanism 240 under the state that the second long link 243 of the first joint cross linkage of the link retaining mechanism 240 is crossed with the first long link 244 of the first joint cross linkage of the link retaining mechanism 240 . The first short link 241 of the first joint cross linkage of the link retaining mechanism 240 is integrally formed with and fixedly connected with the first arm link 221 of the second arm link mechanism 220 . The second long link 243 of the first joint cross linkage of the link retaining mechanism 240 are integrally formed with and fixedly connected with the third arm link 213 of the first arm link mechanism 210 and the third arm link 223 of the second arm link mechanism 220 .

The link retaining mechanism 240 further comprises a second joint cross linkage. The second joint cross linkage is a quadric crank chain and includes a first short link 245 , a first long link 248 , a second short link 246 , and a second long link 247 .

The first short link 245 has first and second end portions. The first short link 245 of the second joint cross linkage of the link retaining mechanism 240 is substantially equal in length to the second long link 243 of the first joint cross linkage of the link retaining mechanism 240 , and integrally formed with and fixedly connected with third arm link 213 of the first arm link mechanism 210 and the third arm link 223 of the second arm link mechanism 220 . The first long link 248 has first and second end portions and longer than the first short link 245 of the second joint cross linkage of the link retaining mechanism 240 . The first short and long links 245 , 248 of the second joint cross linkage of the link retaining mechanism 240 are pivotably connected with each other at the second end portion of the first short link 245 of the second joint cross linkage of the link retaining mechanism 240 and the first end portion of the first long link 248 of the second joint cross linkage of the link retaining mechanism 240 . The second short link 242 of the first joint cross linkage of the link retaining mechanism 240 is integrally formed with and fixedly connected with the first long link 248 of the second joint cross linkage of the link retaining mechanism 240 . The second short link 246 having first and second end portions and substantially equal in length to the first short link 245 of the second joint cross linkage of the link retaining mechanism 240 , the first long link 248 of the second joint cross linkage of the link retaining mechanism 240 and the second short link 246 of the second joint cross linkage of the link retaining mechanism 240 are pivotably connected with each other at the second end portion of the first long link 248 of the second joint cross linkage of the link retaining mechanism 240 and the first end portion of the second short link 246 of the second joint cross linkage of the link retaining mechanism 240 . The second long link 247 has first and second end portions and substantially equal in length to the first long link 248 of the second joint cross linkage of the link retaining mechanism 240 . The second short and long links 246 , 247 of the second joint cross linkage of the link retaining mechanism 240 are pivotably connected with each other at the second end portion of the second short link 246 of the second joint cross linkage of the link retaining mechanism 240 and the first end portion of the second long link 247 of the second joint cross linkage of the link retaining mechanism 240 . The second long link 247 of the second joint cross linkage of the link retaining mechanism 240 and the first short link 245 of the second joint cross linkage of the link retaining mechanism 240 are pivotably connected with each other at the second end portion of the second long link 247 of the second joint cross linkage of the link retaining mechanism 240 and the first end portion of the first short link 245 of the second joint cross linkage of the link retaining mechanism 240 under the state that the second long link 247 of the second joint cross linkage of the link retaining mechanism 240 is crossed with the first long link 248 of the second joint cross linkage of the link retaining mechanism 240 . The second long link 247 of the second joint cross linkage of the link retaining mechanism 240 is integrally formed with and fixedly connected with the first arm link 211 of the first arm link mechanism 210 .

The robot arm member 251 has first and second end portions. The first end portion of the robot arm member 251 is integrally formed with and fixedly connected with the fourth arm link 224 of the second arm link mechanism 220 . The handling member 252 is fixedly connected with the second end portion of the robot arm member 251 . The handling member 252 is adapted to support and handle an object. According to the present invention, the handling member 252 may be adapted to, for example, grip the object.

The robot arm driving mechanism 230 comprises a first driving shaft 231 and a second driving shaft 232 . The first driving shaft 231 is adapted to rotate the first arm link 211 of the first arm link mechanism 210 around a rotation axis in any one of two rotation directions consisting of a first rotation direction 230 a in which the first arm link 221 of the second arm link mechanism 220 rotates in a rotation direction 230 b opposite to the first rotation direction 230 a , and the first arm link mechanism 210 and the second arm link mechanism 220 are extended, and a second rotation direction 230 b in which the first arm link 221 of the second arm link mechanism 220 rotates in a rotation direction 230 a opposite to the second rotation direction 230 b , and the first arm link mechanism 210 and the second arm link mechanism 220 are contracted. The second driving shaft 232 is adapted to rotate the fourth arm link 214 of the first arm link mechanism 210 around the rotation axis in any one of two rotation directions consisting of the first rotation direction 230 a and the second rotation direction 230 b.

Furthermore, the robot arm driving mechanism 230 is adapted to rotate the first arm link 211 of the first arm link mechanism 210 around the rotation axis in the first rotation direction 230 a , and the fourth arm link 214 of the first arm link mechanism 210 around the rotation axis in any one of two directions consisting of the first rotation direction 230 a and the second rotation direction 230 b while maintaining the second angle θ 202 formed by a line 221 a passing through the first arm link 221 of the second arm link mechanism 220 with the reference line 200 a less than a third angle θ 203 formed by a line 224 a passing through the fourth arm link 224 of the second arm link mechanism 220 with the reference line 200 a in the rotation direction 230 b opposite to the first rotation direction 230 a as shown in FIG. 7. The third angle θ 203 ranges from 0 to less than 180 degrees.

The operation of the second embodiment of the robot arm mechanism 200 will be described, hereinlater.

The first driving shaft 231 is operated to rotate the first arm link 211 of the first arm link mechanism 210 around the rotation axis in, for example, the first rotation direction 230 a , the first arm link 221 of the second arm link mechanism 220 is then operated to rotate around the rotation axis in a rotation direction 230 b opposite to the first rotation direction 230 a , and the first arm link mechanism 210 and the second arm link mechanism 220 are operated to be extended. The first driving shaft 231 , on the other hand, is operated to rotate the first arm link 211 of the first arm link mechanism 210 around a rotation axis in, for example, the second rotation direction 230 b , the first arm link 221 of the second arm link mechanism 220 is then operated to rotate around the rotation axis in a rotation direction 230 a opposite to the second rotation direction 230 b , and the first arm link mechanism 210 and the second arm link mechanism 220 are contracted. The first driving shaft 231 is operated to rotate the first arm link 211 of the first arm link mechanism 210 around the rotation axis to change the first angle θ 201 , and the first arm link 211 of the first arm link mechanism 210 is operated to rotate around the rotation axis to change the second angle θ 202 formed by a line 221 a passing through the first arm link 221 of the second arm link mechanism 220 with the reference line 200 a wherein the first angle θ 201 is substantially equal to the second angle θ 202 as described earlier.

This means that the first driving shaft 231 may rotate the first arm link 211 of the first arm link mechanism 210 around the rotation axis in the first rotation direction 230 a , and the first arm link 221 of the second arm link mechanism 220 may rotate around the rotation axis in a rotation direction 230 b opposite to the first rotation direction 230 a until the first arm link mechanism 210 and the second arm link mechanism 220 assumes an extended position as shown in FIG. 6. The first driving shaft 231 , on the other hand, may rotate the first arm link 211 of the first arm link mechanism 210 around the rotation axis in the second rotation direction 230 b , and the first arm link 221 of the second arm link mechanism 220 may rotate around the rotation axis in a rotation direction 230 a opposite to the second rotation direction 230 b , and the first arm link mechanism 210 and the second arm link mechanism 220 are contracted until the first arm link mechanism 210 and the second arm link mechanism 220 assumes a contracted position as shown in FIG. 8. Alternatively, the first arm link mechanism 210 and the second arm link mechanism 220 may further be contracted beyond the contracted position shown in FIG. 8.

The first driving shaft 231 and the second driving shaft 232 may respectively rotate the first arm link 211 of the first arm link mechanism 210 and the fourth arm link 214 of the first arm link mechanism 210 around the rotation axis in the same rotation direction, for example, the first rotation direction 230 a or the second rotation direction 230 b for the same amount of rotation angle, the robot arm mechanism 200 as a whole, including the first arm link mechanism 210 and the second arm link mechanism 220 , is then rotated around the rotation axis in the rotation direction.

As described hereinbefore, the robot arm driving mechanism 230 is operated to rotate the first arm link 211 of the first arm link mechanism 210 around the rotation axis in the first rotation direction 230 a , and the fourth arm link 214 of the first arm link mechanism 210 around the rotation axis in any one of two directions consisting of the first rotation direction 230 a and the second rotation direction 230 b while maintaining the second angle θ 202 formed by the line 221 a passing through the first arm link 221 of the second arm link mechanism 220 with the reference line 200 a less than the third angle θ 203 formed by the line 224 a passing through the fourth arm link 224 of the second arm link mechanism 220 with the reference line 200 a in the rotation direction 230 b opposite to the first rotation direction 230 a as shown in FIG. 7 wherein the third angle θ 203 ranges from 0 to less than 180 degrees. This means that the second embodiment of the robot arm mechanism 200 , in which the third angle θ 203 formed by the line 224 a passing through the fourth arm link 224 of the second arm link mechanism 220 with the reference line 200 a in the rotation direction 230 b opposite to the first rotation direction 230 a is maintained greater than the second angle θ 202 formed by the line 221 a passing through the first arm link 221 of the second arm link mechanism 220 with the reference line 200 a (see FIG. 7) while the first arm link mechanism 210 and the second arm link mechanism 220 are extended, can prevent the quadric crank chain constituting the second arm link mechanism 220 from being flattened out while the first arm link mechanism 210 and the second arm link mechanism 220 are extended, thereby improving resistance to deformation while the first arm link mechanism 210 and the second arm link mechanism 220 are extended as shown in FIG. 6, in comparison with the conventional robot arm mechanism 900 shown in FIG. 20 for the reason described hereinlater.

The quadric crank chain constituting the second arm link mechanism 220 of the second embodiment of the robot arm mechanism 200 does not take on a flattened out condition, in which the third angle θ 203 formed by the line 224 a passing through the fourth arm link 224 of the second arm link mechanism 220 with the reference line 200 a in the rotation direction 230 b opposite to the first rotation direction 230 a is, for example, substantially zero degree as shown in FIG. 9( a ), which the quadric crank chain constituting the second arm link mechanism 920 of the conventional robot arm mechanism 900 takes on when the conventional robot arm mechanism 900 assumes, for example, an extended position shown in FIG. 20, because of the fact that the robot arm driving mechanism 230 is operated to rotate the first arm link 211 of the first arm link mechanism 210 and the fourth arm link 214 of the first arm link mechanism 210 around the rotation axis while maintaining the second angle θ 202 formed by the line 221 a passing through the first arm link 221 of the second arm link mechanism 220 with the reference line 200 a less than the third angle θ 203 formed by the line 224 a passing through the fourth arm link 224 of the second arm link mechanism 220 with the reference line 200 a in the rotation direction 230 b opposite to the first rotation direction 230 a as best shown in FIG. 9( b ), thereby preventing the first quadric crank chain constituting the second arm link mechanism 220 from being flattened out while the first arm link mechanism 210 and the second arm link mechanism 220 are extended. This means that the third arm link 223 and the fourth arm link 224 of the second arm link mechanism 220 are kept forward in the rotation direction 230 b opposite to the first rotation direction 230 a with respect to the reference line 200 a in comparison with the third arm link 923 and the fourth arm link 924 of the second arm link mechanism 920 of the conventional robot arm mechanism 900 .

A force F 201 , for example, substantially perpendicular to the reference line 200 a is exerted on the quadric crank chain constituting the second arm link mechanism 220 of the robot arm mechanism 200 on the supposition that the quadric crank chain constituting the second arm link mechanism 220 of the robot arm mechanism 200 should take on a flattened out condition, which the quadric crank chain constituting the second arm link mechanism 920 of the conventional robot arm mechanism 900 takes on when the conventional robot arm mechanism 900 assumes, for example, an extended position shown in FIG. 20, the force F 201 exerted on the second arm link mechanism 220 can be resolved into a component force F 202 exerted on the first arm link 221 of the second arm link mechanism 220 and a component force F 203 exerted on the fourth arm link 224 of the second arm link mechanism 220 as shown in FIG. 9( a ). The same force F 201 substantially perpendicular to the reference line 200 a , on the other hand, is exerted on the quadric crank chain constituting the second arm link mechanism 220 of the second embodiment of the robot arm mechanism 200 , the force F 201 exerted on the second arm link mechanism 220 can be resolved into a component force F 204 exerted on the first arm link 221 of the second arm link mechanism 220 , which is smaller than the component force F 202 , and a component force F 205 exerted on the fourth arm link 224 of the second arm link mechanism 220 , which is smaller than the component force F 203 , as shown in FIG. 4( b ).

While it has been described in the above that the force F 201 substantially perpendicular to the reference line 100 a and exerted on the quadric crank chain constituting the second arm link mechanism 220 of the robot arm mechanism 200 are resolved into component forces F 204 , F 205 respectively exerted on the first arm link 221 of second arm link mechanism 220 and the fourth arm link 224 of the second arm link mechanism 220 , which are reduced in comparison with component forces F 202 , F 203 to be resolved from the force F 201 exerted on the second arm link mechanism 920 and respectively exerted on the first arm link 921 of the second arm link mechanism 920 and the fourth arm link 924 of the second arm link mechanism 920 of the conventional robot arm mechanism 900 , a force parallel with the reference line 200 a exerted on the quadric crank chain constituting the second arm link mechanism 220 of the robot arm mechanism 200 may be resolved into component forces exerted on respective arm links constituting the second arm link mechanism 220 , which are reduced in comparison with component forces to be resolved from the same force exerted on the second arm link mechanism 920 and exerted on respective arm links constituting the second arm link mechanism 920 of the conventional robot arm mechanism 900 in a similar manner as described above.

While it has been described in the above that the handling member 252 is fixedly connected with the second end portion of the robot arm member 251 , the handling member 252 may be fixedly connected with the second arm link mechanism 220 without the handling member 252 in a manner that the handling member 252 is fixedly connected with, for example, one of the arm links constituting the second arm link mechanism 120 such as, for example, the first, second, and f

6450757	Conveyor system	September, 2002	Saeki
6558107	Robot arm mechanism	May, 2003	Okuno
7001139	Robot arm mechanism	February, 2006	Mori et al.	414/744.5

DE19954832	May, 2000
EP0396752	November, 1990	INDUSTRIAL ROBOT.
EP1207025	May, 2002	CONVEYOR SYSTEM
WO/2000/029176	May, 2000	CONVEYOR SYSTEM