Morgan, Frederick M. (Quincy, MA, US)
Lys, Ihor A. (Boston, MA, US)
Dowling, Kevin J. (Westford, MA, US)
Mueller, George G. (Boston, MA, US)
Plaque It!
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What is claimed is:
1. A lighting fixture for producing a beam of light having a luminous flux spectrum emulating that of a beam of light produced by a predetermined light source having an incandescent lamp, such light source being free of a filter that modifies the luminous flux spectrum of the light emitted by the lamp, the lighting fixture comprising: a plurality of groups of light-emitting devices, each such group configured to emit light having a distinct luminous flux spectrum; and a controller configurable to supply selected amounts of electrical power to the plurality of groups of light-emitting devices, such that the groups cooperate to produce a composite beam of light having a prescribed luminous flux spectrum that has a normalized mean deviation across the visible spectrum of less than about 30% relative to the luminous flux spectrum of a beam of light produced by the predetermined light source to be emulated.
2. A lighting fixture as defined in claim 1, wherein the quantities of devices included in each of the plurality of groups of light-emitting devices are selected such that, if the controller supplies maximum electrical power to all of the groups, then the resulting composite beam of light will have a luminous flux spectrum having a normalized mean deviation across the visible spectrum of less than about 30% relative to the luminous flux spectrum of a beam of light produced by the predetermined light source to be emulated.
3. A lighting fixture as defined in claim 1, wherein the quantities of devices included in each of the plurality of groups of light-emitting devices are selected such that, if the controller supplies maximum electrical power to all of the groups, then the resulting composite beam of light will have a luminous flux spectrum having a normalized mean deviation across the visible spectrum of less than about 30% relative to the luminous flux spectrum of a theoretical beam of light produced by a predetermined light source having an incandescent lamp, as modified by a theoretical superposition of the spectral transmissions of a plurality of color filters.
4. A lighting fixture as defined in claim 1 wherein the controller further is configurable to supply selected amounts of electrical power to the plurality of groups of light-emitting devices, such that the groups cooperate to produce a composite beam of light having a prescribed luminous flux spectrum that has a normalized mean deviation across the visible spectrum of less than about 30% relative to the luminous flux spectrum of a beam of light produced by a predetermined light source that includes an incandescent lamp and a filter that modifies the luminous flux spectrum of the light emitted by such lamp.
5. A lighting fixture as defined in claim 1, wherein at least two of the plurality of groups of light-emitting devices include different quantifies of light-emitting devices.
6. A lighting fixture as defined in claim 1, wherein the plurality of groups of light-emitting devices include at least five groups of light-emitting devices, each such group being configured to emit light having a predetermined distinct luminous flux spectrum.
7. A lighting fixture as defined in claim 1, wherein the plurality of groups of light-emitting devices include at least eight groups of light-emitting devices, each such group being configured to emit light having a predetermined distinct luminous flux spectrum.
8. A lighting fixture as defined in claim 1, wherein each of the plurality of groups of light-emitting devices includes a plurality of light-emitting diodes.
9. A lighting fixture as defined in claim 1, wherein the plurality of groups of light-emitting devices together comprise an optical assembly that collects the emitted light and projects the composite beam of light from the fixture.
10. A lighting fixture as defined in claim 1, wherein the luminous flux spectrum of the composite beam of light has a normalized mean deviation across the visible spectrum of less than about 25% relative to the luminous flux spectrum of a beam of light produced by the predetermined light source to be emulated.
11. A lighting fixture as defined in claim 1, wherein the luminous flux spectrum of the composite beam of light has a normalized mean deviation across the visible spectrum of less than about 20% relative to the luminous flux spectrum of a beam of light produced by the predetermined light source to be emulated.
12. A lighting fixture as defined in claim 1, wherein the luminous flux spectra of the beam of light produced by the lighting fixture and of the beam of light produced by the predetermined light source to be emulated are within 5 db of each other across the visible spectrum when the controller supplies prescribed maximum amounts of electrical power to all of the groups of light-emitting devices.
13. A lighting fixture as defined in claim 1, wherein the predetermined distinct luminous flux spectrum of the light emitted by each of the plurality of groups of light-emitting devices has a spectral half-width of less than about 40 nanometers.
14. A lighting fixture as defined in claim 1, wherein: the distinct luminous flux spectrum of the light emitted by each of the plurality of groups of light-emitting devices has a predetermined peak flux wavelength and a predetermined spectral half-width; the peak flux wavelength of each of the plurality of groups of light-emitting devices is spaced less than about 50 nanometers from the peak flux wavelength of another of the plurality of groups of light-emitting devices; and the spectral half-width of each of the plurality of groups of light-emitting devices is less than about 40 nanometers.
15. A lighting fixture for producing a beam of colored light having a prescribed luminous flux spectrum, the lighting fixture comprising: a plurality of groups of light-emitting devices, each such group configured to emit light having a distinct luminous flux spectrum; and a controller configurable to supply selected amounts of electrical power to the plurality of groups of light-emitting devices, such that the groups cooperate to produce a composite beam of light; wherein the composite beam of light has a prescribed luminous flux spectrum having substantial energy only within a contiguous bandwidth of less than about 200 nanometers when the controller supplies prescribed maximum amounts of electrical power to all of the groups of light-emitting devices.
16. A lighting fixture as defined in claim 15, wherein: each group of light-emitting devices is free of a filter that substantially changes the luminous flux spectrum of its emitted light; and the controller is configurable to supply selected amounts of electrical power to the plurality of groups of light-emitting devices, such that the composite beam of light has a prescribed luminous flux spectrum emulating that of a predetermined light source having an incandescent lamp, such light source further having an associated filter that modifies the luminous flux spectrum of the light emitted by the lamp.
17. A lighting fixture as defined in claim 16, wherein the luminous flux spectrum of the composite beam of light has a normalized mean deviation across the visible spectrum of less than about 30% relative to the luminous flux spectrum of a beam of light produced by the predetermined light source to be emulated.
18. A lighting fixture as defined in claim 16, wherein the quantities of devices included in each of the plurality of groups of light-emitting devices are selected such that, if the controller supplies maximum electrical power to all of the groups, then the resulting composite beam of light will have a luminous flux spectrum having a normalized mean deviation across the visible spectrum of less than about 30% relative to the luminous flux spectrum of a theoretical beam of light produced by the predetermined light source, as modified by a theoretical superposition of the spectral transmissions of a plurality of color filters.
19. A lighting fixture as defined in claim 15, wherein the composite beam of light produced by the plurality of groups of light-emitting devices has a luminous flux spectrum having substantial energy only in wavelengths of less than about 600 nanometers when the controller supplies prescribed maximum amounts of electrical power to all of the groups of light-emitting devices.
20. A lighting fixture as defined in claim 15, wherein the composite beam of light produced by the plurality of groups of light-emitting devices has a luminous flux spectrum having substantial energy only in wavelengths of more than about 550 nanometers when the controller supplies prescribed maximum amounts of electrical power to all of the groups of light-emitting devices.
21. A lighting fixture as defined in claim 15, wherein at least two of the plurality of groups of light-emitting devices include different quantities of light-emitting devices.
22. A lighting fixture as defined in claim 15, wherein the plurality of groups of light-emitting devices include at least four groups of light-emitting devices, each such group being configured to emit light having a predetermined distinct luminous flux spectrum.
23. A lighting fixture as defined in claim 15, wherein each of the plurality of groups of light-emitting devices includes a plurality of light-emitting diodes.
24. A lighting fixture as defined in claim 15, wherein: the distinct luminous flux spectrum of the light emitted by each of the plurality of groups of light-emitting devices has a predetermined peak flux wavelength and a predetermined spectral half-width; the peak flux wavelength of each of the plurality of groups of light-emitting devices is spaced less than about 50 nanometers from the peak flux wavelength of another of the plurality of groups of light-emitting devices; and the spectral half-width of each of the plurality of groups of light-emitting devices is less than about 40 nanometers.
25. A lighting fixture as defined in claim 15, wherein the composite beam of light has a luminous flux spectrum having substantial energy only within a contiguous bandwidth of less than about 150 nanometers.
26. A lighting fixture as defined in claim 15, wherein no portion of the contiguous flux spectrum of the composite beam of light has a flux intensity more than 5 db lower than flux intensities at wavelengths both above and below it.
27. A lighting fixture as defined in claim 15, wherein no portion of the contiguous flux spectrum of the composite beam of light has a flux intensity more than 2 db lower than flux intensities at wavelengths both above and below it.
28. A lighting fixture for producing a beam of light having a prescribed luminous flux spectrum, the lighting fixture comprising: a plurality of groups of light-emitting devices, each such group configured to emit light having a distinct luminous flux spectrum, and at least two of the plurality of groups including different quantities of devices; and a controller configurable to supply selected amounts of electrical power to the plurality of groups of light-emitting devices, such that the groups cooperate to produce a composite beam of light having a prescribed luminous flux spectrum.
29. A lighting fixture as defined in claim 28, wherein: each of the plurality of groups of light-emitting devices is free of a filter that substantially changes the luminous flux spectrum of its emitted light; the prescribed luminous flux spectrum is made to emulate that of a beam of light produced by a predetermined light source having an incandescent lamp, such light source being free of a filter that modifies the luminous flux spectrum of the light emitted by the lamp; and the controller is configurable to supply selected amounts of electrical power to the plurality of groups of light-emitting devices, such that the composite beam of light has a prescribed luminous flux spectrum that has a normalized mean deviation across the visible spectrum of less than about 30% relative to the luminous flux spectrum of a beam of light produced by the predetermined light source to be emulated.
30. A lighting fixture as defined in claim 29, wherein the quantities of devices included in each of the plurality of groups of light-emitting devices are selected such that, if the controller supplies maximum electrical power to all of the groups, then the resulting composite beam of light will have a luminous flux spectrum having a normalized mean deviation across the visible spectrum of less than about 30% relative to the luminous flux spectrum of a beam of light produced by the predetermined light source to be emulated.
31. A lighting fixture as defined in claim 29, wherein the luminous flux spectra of the beam of light produced by the lighting fixture and of the beam of light produced by the light source to be emulated are within 5 db of each other across the visible spectrum when the controller supplies prescribed maximum amounts of electrical power to all of the groups of light-emitting devices.
32. A lighting fixture as defined in claim 28, wherein: each group of light-emitting devices is free of a filter that substantially changes the luminous flux spectrum of its emitted light; the prescribed luminous flux spectrum is made to emulate that of a beam of light produced by a predetermined light source having an incandescent lamp, such light source further having an associated filter that modifies the luminous flux spectrum of the light emitted by the lamp; and the controller is configurable to supply selected amounts of electrical power to at least two of the plurality of groups of light-emitting devices, such that the composite beam of light has a prescribed luminous flux spectrum that has a normalized mean deviation across the visible spectrum of less than about 30% relative to the luminous flux spectrum of a beam of light produced by the predetermined light source to be emulated.
33. A lighting fixture as defined in claim 28, wherein the plurality of groups of light-emitting devices include at least four groups of light-emitting devices, each such group being configured to emit light having a predetermined distinct luminous flux spectrum.
34. A lighting fixture as defined in claim 28, wherein each of the plurality of groups of light-emitting devices includes a plurality of light-emitting diodes.
35. A lighting fixture as defined in claim 28, wherein: the distinct luminous flux spectrum of the light emitted by each of the plurality of groups of light-emitting devices has a predetermined peak flux wavelength and a predetermined spectral half-width; the peak flux wavelength of each of the plurality of groups of light-emitting devices is spaced less than about 50 nanometers from the peak flux wavelength of another of the plurality of groups of light-emitting devices; and the spectral half-width of each of the plurality of groups of light-emitting devices is less than about 40 nanometers.
36. A lighting fixture for producing a beam of light having a prescribed luminous flux spectrum, the lighting fixture comprising: five or more groups of light-emitting devices, wherein each such group is configured to emit light having a distinct luminous flux spectrum; and a controller configurable to supply selected amounts of electrical power to the five or more groups of light-emitting devices, such that the groups cooperate to produce a composite beam of light having a prescribed luminous flux spectrum.
37. A lighting fixture as defined in claim 36, wherein the five or groups of light-emitting devices include at least eight groups of light-emitting devices, each such group being configured to emit light having a predetermined distinct luminous flux spectrum.
38. A lighting fixture as defined in claim 36, wherein each of the five or more groups of light-emitting devices includes a plurality of light-emitting diodes.
39. A lighting fixture as defined in claim 36, wherein: the distinct luminous flux spectrum of the light emitted by each of the five or more groups of light-emitting devices has a predetermined peak flux wavelength and a predetermined spectral half-width; the peak flux wavelength of each of the plurality of groups of light-emitting devices is spaced less than about 50 nanometers from the peak flux wavelength of another of the plurality of groups of light-emitting devices; and the spectral half-width of each of the plurality of groups of light-emitting devices is less than about 40 nanometers.
40. A lighting fixture as defined in claim 36, wherein the five or more groups of light-emitting devices cooperate to emit light spanning substantially the entire visible spectrum.
41. A lighting fixture for producing a beam of light having a prescribed luminous flux spectrum, the lighting fixture comprising: three or more groups of light-emitting devices, each such group configured to emit light having a distinct luminous flux spectrum with a predetermined peak flux wavelength and a predetermined spectral half-width; wherein the peak flux wavelength of each of the four or more groups of light-emitting devices is spaced less than about 50 nanometers from the peak flux wavelength of another of the groups of light-emitting devices; and wherein the spectral half-width of each of the four or more groups of light-emitting devices is less than about 40 nanometers; and a controller configurable to supply selected amounts of electrical power to the four or more groups of light-emitting devices, such that the groups cooperate to produce a composite beam of light having a prescribed luminous flux spectrum.
42. A lighting fixture as defined in claim 41, wherein the three or more groups of light-emitting devices include eight or more groups of light-emitting devices, each such group configured to emit light having a distinct luminous flux spectrum with a predetermined peak flux wavelength and a predetermined spectral half-width.
43. A lighting fixture as defined in claim 41, wherein: each of the plurality of groups of light-emitting devices is free of a filter that substantially changes the luminous flux spectrum of its emitted light; the prescribed luminous flux spectrum is made to emulate that of a beam of light produced by a predetermined light source having an incandescent lamp, such light source being free of a filter that modifies the luminous flux spectrum of the light emitted by the lamp; and the controller is configurable to supply selected amounts of electrical power to the plurality of groups of light-emitting devices, such that the composite beam of light has a prescribed luminous flux spectrum that has a normalized mean deviation across the visible spectrum of less than about 30% relative to the luminous flux spectrum of a beam of light produced by the predetermined light source to be emulated.
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 U.S.C. § 120 as a continuation of U.S. Non-provisional application Ser. No. 09/716,819, filed Nov. 20, 2000, entitled “Systems and Methods for Generating and Modulating Illumination Conditions,” which in turn claims priority to each of the following U.S. Provisional Applications:
[0002] Serial No. 60/166,533, filed Nov. 18, 1999, entitled “Designing Lights with LED Spectrum;”
[0003] Serial No. 60/201,140, filed May 2, 2000, entitled “Systems and Methods for Modulating Illumination Conditions;” and
[0004] Serial No. 60/235,678, filed Sep. 27, 2000, entitled “Ultraviolet Light Emitting Diode Device.”
[0005] Each of the above references is hereby incorporated herein by reference.
BACKGROUND
[0006] Human beings have grown accustomed to controlling their environment. Nature is unpredictable and often presents conditions that are far from a human being's ideal living conditions. The human race has therefore tried for years to engineer the environment inside a structure to emulate the outside environment at a perfect set of conditions. This has involved temperature control, air quality control and lighting control.
[0007] The desire to control the properties of light in an artificial environment is easy to understand. Humans are primarily visual creatures with much of our communication being done visually. We can identify friends and loved ones based on primarily visual cues and we communicate through many visual mediums, such as this printed page. At the same time, the human eye requires light to see by and our eyes (unlike those of some other creatures) are particularly sensitive to color.
[0008] With today's ever-increasing work hours and time constraints, less and less of the day is being spent by the average human outside in natural sunlight. In addition, humans spend about a third of their lives asleep, and as the economy increases to 24/7/365, many employees no longer have the luxury of spending their waking hours during daylight. Therefore, most of an average human's life is spent inside, illuminated by manmade sources of light.
[0009] Visible light is a collection of electromagnetic waves (electromagnetic radiation) of different frequencies, each wavelength of which represents a particular “color” of the light spectrum. Visible light is generally thought to comprise those light waves with wavelength between about 400 nm and about 700 nm. Each of the wavelengths within this spectrum comprises a distinct color of light from deep blue/purple at around 400 nm to dark red at around 700 nm. Mixing these colors of light produces additional colors of light. The distinctive color of a neon sign results from a number of discrete wavelengths of light. These wavelengths combine additively to produce the resulting wave or spectrum that makes up a color. One such color is white light.
[0010] Because of the importance of white light, and since white light is the mixing of multiple wavelengths of light, there have arisen multiple techniques for characterization of white light that relate to how human beings interpret a particular white light. The first of these is the use of color temperature, which relates to the color of the light within white. Correlated color temperature is characterized in color reproduction fields according to the temperature in degrees Kelvin (K) of a black body radiator that radiates the same color light as the light in question.
[0011] The second classification of white light involves its quality. In 1965 the Commission Internationale de l'Eclairage (CIE) recommended a method for measuring the color rendering properties of light sources based on a test color sample method. This method has been updated and is described in the CIE 13.3-1995 technical report “Method of Measuring and Specifying Colour Rendering Properties of Light Sources,” the disclosure of which is herein incorporated by reference. In essence, this method involves the spectroradiometric measurement of the light source under test. This data is multiplied by the reflectance spectrums of eight color samples. The resulting spectrums are converted to tristimulus values based on the CIE 1931 standard observer. The shift of these values with respect to a reference light are determined for the uniform color space (UCS) recommended in 1960 by the CIE. The average of the eight color shifts is calculated to generate the General Color Rendering Index, known as CRI. Within these calculations the CRI is scaled so that a perfect score equals 100, where perfect would be using a source spectrally equal to the reference source (often sunlight or fill spectrum white light). For example a tungsten-halogen source compared to full spectrum white light might have a CPU of 99 while a warm white fluorescent lamp would have a CRI of 50.
[0012] Artificial lighting generally uses the standard CRI to determine the quality of white light. If a light yields a high CRI compared to full spectrum white light then it is considered to generate better quality white light (light that is more “natural” and enables colored surfaces to be better rendered). This method has been used since 1965 as a point of comparison for all different types of light sources.
[0013] In addition to white light, the ability to generate specific colors of light is also highly sought after. Because of humans' light sensitivity, visual arts and similar professions desire colored light that is specifiable and reproducible. Elementary film study classes teach that a movie-goer has been trained that light which is generally more orange or red signifies the morning, while light that is generally more blue signifies a night or evening. We have also been trained that sunlight filtered through water has a certain color, while sunlight filtered through glass has a different color. For all these reasons it is desirable for those involved in visual arts to be able to produce exact colors of light, and to be able to reproduce them later.
[0014] Current lighting technology makes such adjustment and control difficult, because common sources of light, such as halogen, incandescent, and fluorescent sources, generate light of a fixed color temperature and spectrum. Further, altering the color temperature or spectrum will usually alter other lighting variables in an undesirable way. For example, increasing the voltage applied to an incandescent light may raise the color temperature of the resulting light, but also results in an overall increase in brightness. In the same way, placing a deep blue filter in front of a white halogen lamp will dramatically decrease the overall brightness of the light. The filter itself will also get quite hot (and potentially melt) as it absorbs a large percentage of the light energy from the white light.
[0015] Moreover, achieving certain color conditions with incandescent sources can be difficult or impossible as the desired color may cause the filament to rapidly burn out. For fluorescent lighting sources, the color temperature is controlled by the composition of the phosphor, which may vary from bulb to bulb but cannot typically be altered for a given bulb. Thus, modulating color temperature of light is a complex procedure that is often avoided in scenarios where such adjustment may be beneficial.
[0016] In artificial lighting, control over the range of colors that can be produced by a lighting fixture is desirable. Many lighting fixtures known in the art can only produce a single color of light instead of range of colors. That color may vary across lighting fixtures (for instance a fluorescent lighting fixture produces a different color of light than a sodium vapor lamp). The use of filters on a lighting fixture does not enable a lighting fixture to produce a range of colors, it merely allows a lighting fixture to produce its single color, which is then partially absorbed and partially transmitted by the filter. Once the filter is placed, the fixture can only produce a single (now different) color of light, but cannot produce a range of colors.
[0017] In control of artificial lighting, it is further desirable to be able to specify a point within the range of color producible by a lighting fixture that will be the point of highest intensity. Even on current technology lighting fixtures whose colors can be altered, the point of maximum intensity cannot be specified by the user, but is usually determined by unalterable physical characteristics of the fixture. Thus, an incandescent light fixture can produce a range of colors, but the intensity necessarily increases as the color temperature increases which does not enable control of the color at the point of maximum intensity. Filters further lack control of the point of maximum intensity, as the point of maximum intensity of a lighting fixture will be the unfiltered color (any filter absorbs some of the intensity).
SUMMARY
[0018] Applicants have appreciated that the correlated color temperature, and CRI, of viewing light can affect the way in which an observer perceives a color image. An observer will perceive the same color image differently when viewed under lights having different correlated color temperatures. For example, a color image which looks normal when viewed in early morning daylight will look bluish and washed out when viewed under overcast midday skies. Further, a white light with a poor CRI may cause colored surfaces to appear distorted.
[0019] Applicants also have appreciated that the color temperature and/or CRI of light is critical to creators of images, such as photographers, film and television producers, painters, etc., as well as to the viewers of paintings, photographs, and other such images. Ideally, both creator and viewer utilize the same color of ambient light, ensuring that the appearance of the image to the viewer matches that of the creator.
[0020] Applicants have further appreciated that the color temperature of ambient light affects how viewers perceive a display, such as a retail or marketing display, by changing the perceived color of such items as fruits and vegetables, clothing, furniture, automobiles, and other products containing visual elements that can greatly affect how people view and react to such displays. One example is a tenet of theatrical lighting design that strong green light on the human body (even if the overall lighting effect is white light) tends to make the human look unnatural, creepy, and often a little disgusting. Thus, variations in the color temperature of lighting can affect how appealing or attractive such a display may be to customers.
[0021] Moreover, the ability to view a decoratively colored item, such as fabric-covered furniture, clothing, paint, wallpaper, curtains, etc., in a lighting environment or color temperature condition which matches or closely approximates the conditions under which the item will be viewed would permit such colored items to be more accurately matched and coordinated. Typically, the lighting used in a display setting, such as a showroom, cannot be varied and is often chosen to highlight a particular facet of the color of the item leaving a purchaser to guess as to whether the item in question will retain an attractive appearance under the lighting conditions where the item will eventually be placed. Differences in lighting can also leave a customer wondering whether the color of the item will clash with other items that cannot conveniently be viewed under identical lighting conditions or otherwise directly compared.
[0022] In view of the foregoing, one embodiment of the present invention relates to systems and methods for generating and/or modulating illumination conditions to generate light of a desired and controllable color, for creating lighting fixtures for producing light in desirable and reproducible colors, and for modifying the color temperature or color shade of light produced by a lighting fixture within a prespecified range after a lighting fixture is constructed. In one embodiment, LED lighting units capable of generating light of a range of colors are used to provide light or supplement ambient light to afford lighting conditions suitable for a wide range of applications.
[0023] Disclosed is a first embodiment which comprises a lighting fixture for generating white light including a plurality of component illumination sources (such as LEDs), producing electromagnetic radiation of at least two different spectrums (including embodiments with exactly two or exactly three), each of the spectrums having a maximum spectral peak outside the region 510 nm to 570 nm, the illumination sources mounted on a mounting allowing the spectrums to mix so that the resulting spectrum is substantially continuous in the photopic response of the human eye and/or in the wavelengths from 400 nm to 700 nm.
[0024] In another embodiment, the lighting fixture can include illumination sources that are not LEDs possibly with a maximum spectral peak within the region 510 nm to 570 nm. In yet another embodiment, the fixture can produce white light within a range of color temperatures such as, but not limited to, the range 500K to 10,000K and the range 2300 K to 4500 K. The specific color or color temperature in the range may be controlled by a controller. In an embodiment the fixture contains a filter on at least one of the illumination sources which may be selected, possibly from a range of filters, to allow the fixture to produce a particular range of colors. The lighting fixture may also include in one embodiment illumination sources with wavelengths outside the above discussed 400 nm to 700 nm range.
[0025] In another embodiment, the lighting fixture can comprise a plurality of LEDs producing three spectrums of electromagnetic radiation with maximum spectral peaks outside the region of 530 nm, to 570 nm (such as 450 nm and/or 592 nm) where the additive interference of the spectrums results in white light. The lighting fixture may produce white light within a range of color temperatures such as, but not limited to, the range 500K to 10,000K and the range 2300K to 4500 K. The lighting fixture may include a controller and/or a processor for controlling the intensities of the LEDs to produce various color temperatures in the range.
[0026] Another embodiment comprises a lighting fixture to be used in a lamp designed to take fluorescent tubes, the lighting fixture having at least one component illumination source (often two or more) such as LEDs mounted on a mounting, and having a connector on the mounting that can couple to a fluorescent lamp and receive power from the lamp. It also contains a control or electrical circuit to enable the ballast voltage of the lamp to be used to power or control the LEDs. This control circuit could include a processor, and/or could control the illumination provided by the fixture based on the power provided to the lamp. The lighting fixture, in one embodiment, is contained in a housing, the housing could be generally cylindrical in shape, could contain a filter, and/or could be partially transparent or translucent. The fixture could produce white, or other colored, light.
[0027] Another embodiment comprises a lighting fixture for generating white light including a plurality of component illumination sources (such as LEDs, illumination devices containing a phosphor, or LEDs containing a phosphor), including component illumination sources producing spectrums of electromagnetic radiation. The component illumination sources are mounted on a mounting designed to allow the spectrums to mix and form a resulting spectrum, wherein the resulting spectrum has intensity greater than background noise at its lowest spectral valley. The lowest spectral valley within the visible range can also have an intensity of at least 5%, 10%, 25%, 50% or 75% of the intensity of its maximum spectral peak. The lighting fixture may be able to generate white light at a range of color temperatures and may include a controller and/or processor for enabling the selection of a particular color or color temperature in that range.
[0028] Another embodiment of a lighting fixture could include a plurality of component illumination sources (such as LEDs), the component illumination sources producing electromagnetic radiation of at least two different spectrums, the illumination sources being mounted on a mounting designed to allow the spectrums to mix and form a resulting spectrum, wherein the resulting spectrum does not have a spectral valley at a longer wavelength than the maximum spectral peak within the photopic response of the human eye and/or in the area from 400 nm to 700 nm.
[0029] Another embodiment comprises a method for generating white light including the steps of mounting a plurality of component illumination sources producing electromagnetic radiation of at least two different spectrums in such a way as to mix the spectrums; and choosing the spectrums in such a way that the mix of the spectrums has intensity greater than background noise at its lowest spectral valley.
[0030] Another embodiment comprises a system for controlling illumination conditions including, a lighting fixture for providing illumination of any of a range of colors, the lighting fixture being constructed of a plurality of component illumination sources (such as LEDs and/or potentially of three different colors), a processor coupled to the lighting fixture for controlling the lighting fixture, and a controller coupled to the processor for specifying illumination conditions to be provided by the lighting fixture. The controller could be computer hardware or computer software; a sensor such as, but not limited to a photodiode, a radiometer, a photometer, a colorimeter, a spectral radiometer, a camera; or a manual interface such as, but not limited to, a slider, a dial, a joystick, a trackpad, or a trackball. The processor could include a memory (such as a database) of predetermined color conditions and/or an interface-providing mechanism for providing a user interface potentially including a color spectrum, a color temperature spectrum, or a chromaticity diagram.
[0031] In another embodiment the system could include a second source of illumination such an, but not limited to, a fluorescent bulb, an incandescent bulb, a mercury vapor lamp, a sodium vapor lamp, an arc discharge lamp, sunlight, moonlight, candlelight, an LED display system, an LED, or a lighting system controlled by pulse width modulation. The second source could be used by the controller to specify illumination conditions for the lighting fixture based on the illumination of the lighting fixture and the second source illumination and/or the combined light from the lighting fixture and the second source could be a desired color temperature.
[0032] Another embodiment comprises a method with steps including generating light having color and brightness using a lighting fixture capable of generating light of any range of colors, measuring illumination conditions, and modulating the color or brightness of the generated light to achieve a target illumination condition. The measuring of illumination conditions could include detecting color characteristics of the illumination conditions using a light sensor such as, but not limited to, a photodiode, a radiometer, a photometer, a calorimeter, a spectral radiometer, or a camera; visually evaluating illumination conditions, and modulating the color or brightness of the generated light includes varying the color or brightness of the generated light using a manual interface; or measuring illumination conditions including detecting color characteristics of the illumination conditions using a light sensor, and modulating the color or brightness of the generated light including varying the color or brightness of the generated light using a processor until color characteristics of the illumination conditions detected by the light sensor match color characteristics of the target illumination conditions. The method could include selecting a target illumination condition such as, but not limited to, selecting a target color temperature and/or providing an interface comprising a depiction of a color range and selecting a color within the color range. The method could also have steps for providing a second source of illumination, such as, but not limited to, a fluorescent bulb, an incandescent bulb, a mercury vapor lamp, a sodium vapor lamp, an arc discharge lamp, sunlight, moonlight, candlelight, an LED lighting system, an LED, or a lighting system controlled by pulse width modulation. The method could measure illumination conditions including detecting light generated by the lighting fixture and by the second source of illumination.
[0033] In another embodiment modulating the color or brightness of the generated light includes varying the illumination conditions to achieve a target color temperature or the lighting fixture could comprise one of a plurality of lighting fixtures, capable of generating a range of colors.
[0034] In yet another embodiment there is a method for designing a lighting fixture comprising, selecting a desired range of colors to be produced by the lighting fixture, choosing a selected color of light to be produced by the lighting fixture when the lighting fixture is at maximum intensity, and designing the lighting fixture from a plurality of illumination sources (such as LEDs) such that the lighting fixture can produce the range of colors, and produces the selected color when at maximum intensity.
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION
[0071] The description below pertains to several illustrative embodiments of the invention. Although many variations of the invention may be envisioned by one skilled in the art, such variations and improvements are intended to fall within the scope of this disclosure. Thus, the scope of the invention is not to be unduly limited in any way by the disclosure below.
[0072] As used in this document, the following terms generally have the following meanings; however, these definitions are in no way intended to limit the scope of the term as would be understood by one of skill in the art.
[0073] As used herein, the term “LED system” means any electroluminescent diode or other type of carrier injection/junction-based system that is capable of receiving an electrical signal and producing radiation in response to the signal. Thus, the term “LED” generally includes light emitting diodes of all types and also includes, but is not limited to, light emitting polymers, semiconductor dies that produce light in response to a current, organic LEDs, electron luminescent strips, super luminescent diodes (SLDs) and other such devices. In an embodiment, an “LED” may refer to a single light emitting diode having multiple semiconductor dies that are individually controlled. The term LEDs does not restrict the physical or electrical packaging of any of the above and that packaging could include, but is not limited to, surface mount, chip-on-board, or T-package mount LEDs and LEDs of all other configurations. The term “LED” also includes LEDs packaged or associated with material (e.g. a phosphor) wherein the material may convert energy from the LED to a different wavelength. For example, the term “LED” also includes constructions that include a phosphor where the LED emission pumps the phosphor and the phosphor converts the energy to longer wavelength energy. White LEDs typically use an LED chip that produces short wavelength radiation and the phosphor is used to convert the energy to longer wavelengths. This construction also typically results in broadband radiation as compared to the original chip radiation.
[0074] “Illumination source” includes all illumination sources, including, but not limited to, LEDs; incandescent sources including filament lamps; pyro-luminescent sources such as flames; candle-luminescent sources such as gas mantles and carbon arc radiation sources; photo-luminescent sources including gaseous discharges; fluorescent sources; phosphorescence sources; lasers; electro-luminescent sources such as electro-luminescent lamps; cathode luminescent sources using electronic satiation; and miscellaneous luminescent sources including galvano-luminescent sources, crystallo-luminescent sources, kine-luminescent sources, thermo-luminescent sources, tribo-luminescent sources, sono-luminescent sources, and radio-luminescent sources. Illumination sources may also include luminescent polymers. An illumination source can produce electromagnetic radiation within the visible spectrum, outside the visible spectrum, or a combination of both. A component illumination source is any illumination source that is part of a lighting fixture.
[0075] “Lighting fixture” or “fixture” is any device or housing containing at least one illumination source for the purposes of providing illumination.
[0076] “Color,” “temperature” and “spectrum” are used interchangeably within this document unless otherwise indicated. The three terms generally refer to the resultant combination of wavelengths of light that result in the light produced by a lighting fixture. That combination of wavelengths defines a color or temperature of the light. Color is generally used for light which is not white, while temperature is for light that is white, but either term could be used for any type of light. A white light has a color and a non-white light could have a temperature. A spectrum will generally refer to the spectral composition of a combination of the individual wavelengths, while a color or temperature will generally refer to the human perceived properties of that light. However, the above usages are not intended to limit the scope of these terms.
[0077] The recent advent of colored LEDs bright enough to provide illumination has prompted a revolution in illumination technology because of the ease with which the color and brightness of these light sources may be modulated. One such modulation method is discussed in U.S. Pat. No. 6,016,038 the entire disclosure of which is herein incorporated by reference. The systems and methods described herein discuss how to use and build LED light fixtures or systems, or other light fixtures or systems utilizing component illumination sources. These systems have certain advantages over other lighting fixtures. In particular, the systems disclosed herein enable previously unknown control in the light which can be produced by a lighting fixture. In particular, the following disclosure discusses systems and methods for the predetermination of the range of light, and type of light, that can be produced by a lighting fixture and the systems and methods for utilizing the predetermined range of that lighting fixture in a variety of applications.
[0078] To understand these systems and methods it is first useful to understand a lighting fixture which could be built and used in embodiments of this invention.
[0079] The collection of component illumination sources (
[0080] The term “processor” is used herein to refer to any method or system for processing, for example, those that process in response to a signal or data and/or those that process autonomously. A processor should be understood to encompass microprocessors, microcontrollers, programmable digital signal processors, integrated circuits, computer-software, computer hardware, electrical circuits, application specific integrated circuits, programmable logic devices, programmable gate arrays, programmable array logic, personal computers, chips, and any other combination of discrete analog, digital, or programmable components, or other devices capable of providing processing functions.
[0081] The collection of illumination sources (
[0082] Referring to
[0083] As used herein, the term “data connection” should be understood to encompass any system for delivering data, such as a network, a data bus, a wire, a transmitter and receiver, a circuit, a video tape, a compact disc, a DVD disc, a video tape, an audio tape, a computer tape, a card, or the like. A data connection may thus include any system or method to deliver data by radio frequency, ultrasonic, auditory, infrared, optical, microwave, laser, electromagnetic, or other transmission or connection method or system. That is, any use of the electromagnetic spectrum or other energy transmission mechanism could provide a data connection as disclosed herein.
[0084] In an embodiment of the invention, the lighting fixture (
[0085] The control data may be in any form suitable for controlling the processor (
[0086] The foregoing embodiments of a lighting fixture (
[0087]
[0088] Body section (
[0089] Lighting fixture (
[0090] Interposed between lighting fixture (
[0091]
[0092] Further shown in
[0093] In one embodiment, the lighting fixture (
[0094] In one embodiment of the invention, it is recognized that prespecified ranges of available colors may be desirable and it may also be desirable to build lighting fixtures in such a way as to maximize the illumination of the lighting apparatus for particular color therein. This is best shown through a numerical example. Let us assume that a lighting fixture contains 30 component illumination sources in three different wavelengths, primary red, primary blue, and primary green (such as individual LEDs). In addition, let us assume that each of these illumination sources produces the same intensity of light, they just produce at different colors. Now, there are multiple different ways that the thirty illumination sources for any given lighting fixture can be chosen. There could be 10 of each of the illumination sources, or alternatively there could be 30 primary blue colored illumination sources. It should be readily apparent that these light fixtures would be useful for different types of lighting. The second light apparatus produces more intense primary blue light (there are 30 sources of blue light) than the first light source (which only has 10 primary blue light sources, the remaining 20 light sources have to be off to produce primary blue light), but is limited to only producing primary blue light. The second light fixture can produce more colors of light, because the spectrums of the component illumination sources can be mixed in different percentages, but cannot produce as intense blue light. It should be readily apparent from this example that the selection of the individual component illumination sources can change the resultant spectrum of light the fixture can produce. It should also be apparent that the same selection of components can produce lights which can produce the same colors, but can produce those colors at different intensities. To put this another way, the full-on point of a lighting fixture (the point where all the component illumination sources are at maximum) will be different depending on what the component illumination sources are.
[0095] A lighting system may accordingly be specified using a full-on point and a range of selectable colors. This system has many potential applications such as, but not limited to, retail display lighting and theater lighting. Often times numerous lighting fixtures of a plurality of different colors are used to present a stage or other area with interesting shadows and desirable features. Problems can arise, however, because lamps used regularly have similar intensities before lighting filters are used to specify colors of those fixtures. Due to differences in transmission of the various filters (for instance blue filters often loose significantly more intensity than red filters), lighting fixtures must have their intensity controlled to compensate. For this reason, lighting fixtures are often operated at less than their full capability (to allow mixing) requiring additional lighting fixtures to be used. With the lighting fixtures of the instant invention, the lighting fixtures can be designed to produce particular colors at identical intensities of chosen colors when operating at their full potential; this can allow easier mixing of the resultant light, and can result in more options for a lighting design scheme.
[0096] Such a system enables the person building or designing lighting fixtures to generate lights that can produce a pre-selected range of colors, while still maximizing the intensity of light at certain more desirable colors. These lighting fixtures would therefore allow a user to select certain color(s) of lighting fixtures for an application independent of relative intensity. The lighting fixtures can then be built so that the intensities at these colors are the same. Only the spectrum is altered. It also enables a user to select lighting fixtures that produce a particular high-intensity color of light, and also have the ability to select nearby colors of light in a range.
[0097] The range of colors which can be produced by the lighting fixture can be specified instead of, or in addition to, the full-on point. The lighting fixture can then be provided with control systems that enable a user of the lighting fixture to intuitively and easily select a desired color from the available range.
[0098] One embodiment of such a system works by storing the spectrums of each of the component illumination sources. In this example embodiment, the illumination sources are LEDs. By selecting different component LEDs with different spectrums, the designer can define the color range of a lighting fixture. An easy way to visualize the color range is to use the CIE diagram which shows the entire lighting range of all colors of light which can exist. One embodiment of a system provides a light-authoring interface such as an interactive computer interface.
[0099]
[0100] In addition to specifying the color range, the intensities at any given color can be calculated from the LED spectrums. By knowing the number of LEDs for a given color and the maximum intensity of any of these LEDs, the total light output at a particular color is calculated. A diamond or other symbol (
[0101] Because a lighting fixture can be made of a plurality of component illumination sources, when designing a lighting fixture, a color that is most desirable can be selected, and a lighting fixture can be designed that maximizes the intensity of that color. Alternatively, a fixture may be chosen and the point of maximum intensity can be determined from this selection. A tool may be provided to allow calculation of a particular color at a maximum intensity.
[0102] In
[0103] Therefore the system in one embodiment of the invention contains a collection of the spectrums of a number of different LEDs, provides an interface for a user to select LEDs that will produce a range of color that encloses the desirable area, and allows a user to select the number of each LED type such that when the unit is on full, a target color is produced. In an alternative embodiment, the user would simply need to provide a desired spectrum, or color and intensity, and the system could produce a lighting fixture which could generate light according to the requests.
[0104] Once the light has been designed, in one embodiment, it is further desirable to make the light's spectrum easily accessible to the lighting fixture's user. As was discussed above, the lighting fixture may have been chosen to have a particular array of illumination sources such that a particular color is obtained at maximum intensity. However, there may be other colors that can be produced by varying the relative intensities of the component illumination sources. The spectrum of the lighting fixture can be controlled within the predetermined range specified by the area (
[0105] In order to be able to carry out such control of the spectrum of the light, it is desirable in one embodiment to create a system and method for linking the color of the light to a control device for controlling the light's color. Since a lighting fixture can be custom designed, it may, in one embodiment, be desirable to have the intensities of each of the component illumination sources “mapped” to a desirable resultant spectrum of light and allowing a point on the map to be selected by the controller. That is, a method whereby, with the specification of a particular color of light by a controller, the lighting fixture can turn on the appropriate illumination sources at the appropriate intensity to create that color of light. In one embodiment, the lighting fixture design software shown in
[0106] This mapping may be performed by a variety of methods. In one embodiment, statistics are known about each individual component illumination sources within the lighting fixture, so mathematical calculations may be made to produce a relationship between the resulting spectrum and the component spectrums. Such calculations would be well understood by one of skill in the art.
[0107] In another embodiment, an external calibration system may be used. One layout of such a system is disclosed in
[0108] Once the mapping has been completed, other methods or systems may be used for the light fixture's control. Such methods or systems will enable the determination of a desired color, and the production by the lighting fixture of that color.
[0109]
[0110]
[0111] In another embodiment, a manual control system (
[0112] One such manual control system (
[0113] Additionally, instead of a dial, a manual control system (
[0114] In another embodiment, the calibration system depicted in
[0115] The sensor (
[0116] In embodiments wherein the sensor (
[0117] In certain embodiments, the lighting fixture (
[0118] Any of the above systems could be deployed in the system disclosed in
[0119] The above systems allow for the creation of lighting fixtures with virtually any type of spectrum. It is often desirable to produce light that appears “natural” or light which is a high-quality, especially white light.
[0120] A lighting fixture which produces white light according to the above invention can comprise any collection of component illumination sources such that the area defined by the illumination sources can encapsulate at least a portion of the black body curve. The black body curve (
[0121] For a variable color white light with the highest possible intensity, a significant portion of the black body curve may be enclosed. The intensity at different color whites along the black body curve can then be simulated. The maximum intensity produced by this light could be placed along the black body curve. By varying the number of each color LED (in
[0122] Although this system generates white light with a variable color temperature, it is not necessarily a high quality white light source. A number of combinations of colors of illumination sources can be chosen which enclose the black body curve, and the quality of the resulting lighting fixtures may vary depending on the illumination sources chosen.
[0123] Since white light is a mixture of different wavelengths of light, it is possible to characterize white light based on the component colors of light that are used to generate it. Red, green, and blue (RGB) can combine to form white; as can light blue, amber, and lavender; or cyan, magenta and yellow. Natural white light (sunlight) contains a virtually continuous spectrum of wavelengths across the human visible band (and beyond). This can be seen by examining sunlight through a prism, or looking at a rainbow. Many artificial white lights are technically white to the human eye, however, they can appear quite different when shown on colored surfaces because they lack a virtually continuous spectrum.
[0124] As an extreme example one could create a white light source using two lasers (or other narrow band optical sources) with complimentary wavelengths. These sources would have an extremely narrow spectral width perhaps 1 nm wide. To exemplify this, we will choose wavelengths of 635 nm and 493 nm. These are considered complimentary since they will additively combine to make light which the human eye perceives as white light. The intensity levels of these two lasers can be adjusted to some ratio of powers that will produce white light that appears to have a color temperature of 5000K. If this source were directed at a white surface, the reflected light will appear as 5000K white light.
[0125] The problem with this type of white light is that it will appear extremely artificial when shown on a colored surface. A colored surface (as opposed to colored light) is produced because the surface absorbs and reflects different wavelengths of light. If hit by white light comprising a full spectrum (light with all wavelengths of the visible band at reasonable intensity), the surface will absorb and reflect perfectly. However, the white light above does not provide the complete spectrum. To again use an extreme example, if a surface only reflected light from 500 nm-550 nm it will appear a fairly deep green in full-spectrum light, but will appear black (it absorbs all the spectrums present) in the above described laser-generated artificial white light.
[0126] Further, since the CRI index relies on a limited number of observations, there are mathematical loopholes in the method. Since the spectrums for CRI color samples are known, it is a relatively straightforward exercise to determine the optimal wavelengths and minimum numbers of narrow band sources needed to achieve a high CRI. This source will fool the CRI measurement, but not the human observer. The CRI method is at best an estimator of the spectrum that the human eye can see. An everyday example is the modern compact fluorescent lamp. It has a fairly high CRI of 80 and a color temperature of 2980K but still appears unnatural. The spectrum of a compact fluorescent is shown in
[0127] Due to the desirability of high-quality light (in particular high-quality white light) that can be varied over different temperatures or spectrums, a further embodiment of this invention comprises systems and method for generating higher-quality white light by mixing the electromagnetic radiation from a plurality of component illumination sources such as LEDs. This is accomplished by choosing LEDs that provide a white light that is targeted to the human eye's interpretation of light, as well as the mathematical CRI index. That light can then be maximized in intensity using the above system. Further, because the color temperature of the light can be controlled, this high quality white light can therefore still have the control discussed above and can be a controllable, high-quality, light which can produce high-quality light across a range of colors.
[0128] To produce a high-quality white light, it is necessary to examine the human eye's ability to see light of different wavelengths and determine what makes a light high-quality. In it's simplest definition, a high-quality white light provides low distortion to colored objects when they are viewed under it. It therefore makes sense to begin by examining a high-quality light based on what the human eye sees. Generally the highest quality white light is considered to be sunlight or full-spectrum light, as this is the only source of “natural” light. For the purposes of this disclosure, it will be accepted that sunlight is a high-quality white light.
[0129] The sensitivity of the human eye is known as the Photopic response. The Photopic response can be thought of as a spectral transfer function for the eye, meaning that it indicates how much of each wavelength of light input is seen by the human observer. This sensitivity can be expressed graphically as the spectral luminosity function Vλ (
[0130] The eye's Photopic response is important since it can be used to describe the boundaries on the problem of generating white light (or of any color of light). In one embodiment of the invention, a high quality white light will need to comprise only what the human eye can “see.” In another embodiment of the invention, it can be recognized that high-quality white light may contain electromagnetic radiation which cannot be seen by the human eye but may result in a photobiological response. Therefore a high-quality white light may include only visible light, or may include visible light and other electromagnetic radiation which may result in a photobiological response. This will generally be electromagnetic radiation less than 400 nm (ultraviolet light) or greater than 700 nm (infrared light).
[0131] Using the first part of the description, the source is not required to have any power above 700 nm or below 400 nm since the eye has only minimal response at these wavelengths. A high-quality source would preferably be substantially continuous between these wavelengths (otherwise colors could be distorted) but can fall-off towards higher or lower wavelengths due to the sensitivity of the eye. Further, the spectral distribution of different temperatures of white light will be different. To illustrate this, spectral distributions for two blackbody sources with temperatures of 5000K (
[0132] As seen in
[0133] Having examined these relationships of the human eye, a fixture for producing controllable high-quality white light would need to have the following characteristic. The light has a substantially continuous spectrum over the wavelengths visible to the human eye, with any holes or gaps locked in the areas where the human eye is less responsive. In addition, in order to make a high-quality white light controllable over a range of temperatures, it would be desirable to produce a light spectrum which can have relatively equal values of each wavelength of light, but can also make different wavelengths dramatically more or less intense with regards to other wavelengths depending on the color temperature desired. The clearest waveform which would have such control would need to mirror the scope of the photopic response of the eye, while still being controllable at the various different wavelengths.
[0134] As was discussed above, the traditional mixing methods which create white light can create light which is technically “white” but sill produces an abnormal appearance to the human eye. The CRI rating for these values is usually extremely low or possibly negative. This is because if there is not a wavelength of light present in the generation of white light, it is i