Adaptive adjustment of light output of solid state lighting panels
First Claim
1. A lighting panel system, comprising:
- a lighting panel including at least a first string of solid state lighting devices configured to emit light at a first dominant wavelength and a second string of solid state lighting devices configured to emit light at a second dominant wavelength, different from the first dominant wavelength;
a current supply circuit configured to supply an on-state drive current to the first string upon receipt of a control signal;
a photosensor arranged to receive light from at least one solid state lighting device in the first string; and
a control system configured to receive an output signal from the photosensor and to adjust the control signal responsive to the output signal of the photosensor to thereby adjust an average current supplied to the first string by the current supply circuit to thereby change a color point of the combined light emitted by the first string and the second string, wherein the photosensor, the control system and the current supply circuit form a feedback loop for the lighting panel.
3 Assignments
0 Petitions
Accused Products
Abstract
A lighting panel system includes a lighting panel including a first string of solid state lighting devices configured to emit light at a first wavelength and a second string of solid state lighting devices configured to emit light at a second wavelength, different from the first wavelength, and a current supply circuit configured to supply a drive current to the first string in response to a control signal. A photosensor is arranged to receive light emitted by the panel, and a control system is configured to sample an output signal of the photosensor and adjust the control signal responsive thereto to thereby adjust an average current supplied to the first string by the current supply circuit. Methods of operating a lighting panel are also provided.
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Citations
73 Claims
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1. A lighting panel system, comprising:
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a lighting panel including at least a first string of solid state lighting devices configured to emit light at a first dominant wavelength and a second string of solid state lighting devices configured to emit light at a second dominant wavelength, different from the first dominant wavelength;
a current supply circuit configured to supply an on-state drive current to the first string upon receipt of a control signal;
a photosensor arranged to receive light from at least one solid state lighting device in the first string; and
a control system configured to receive an output signal from the photosensor and to adjust the control signal responsive to the output signal of the photosensor to thereby adjust an average current supplied to the first string by the current supply circuit to thereby change a color point of the combined light emitted by the first string and the second string, wherein the photosensor, the control system and the current supply circuit form a feedback loop for the lighting panel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A lighting panel system, comprising:
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a lighting panel including at least a first string of solid state lighting devices configured to emit light at a first dominant wavelength and a second string of solid state lighting devices configured to emit light at a second dominant wavelength, different from the first dominant wavelength;
a first current supply circuit configured to supply an on-state drive current to the first string in response to a first control signal;
a second current supply circuit configured to supply an on-state drive current to the second string in response to a second control signal;
a photosensor arranged to receive light from at least one solid state lighting device in the first string and at least one solid state lighting device in the second string; and
a control system configured to receive an output signal from the photosensor and to adjust the first control signal and/or the second control signal responsive to the output signal of the photosensor to thereby adjust an average current supplied to the first string by the first current supply circuit and/or to adjust an average current supplied to the second string by the second current supply circuit, such that the photosensor, the control system and the first and second current supply circuits thereby form a feedback loop for the lighting panel;
wherein the first and second control signals comprise pulse width modulation (PWM) signals, and wherein the control system is configured to control an average current supplied to the first and/or second string by varying a duty cycle of the first and/or second control signal. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
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33. A lighting panel system, comprising:
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a lighting panel comprising first and second pulsed LED light sources configured to emit narrow band optical radiation having a first dominant wavelength when energized and third and fourth pulsed LED light sources configured to emit narrow band optical radiation having a second dominant-wavelength when energized, the second dominant wavelength being different from the first dominant wavelength;
a photosensor configured to be responsive to the first and second dominant wavelengths and configured to provide substantially independent outputs related to the sensed illumination levels in the first and second dominant wavelengths first, second, third and fourth current sources configured to supply current to the first, second, third and fourth pulsed LED light sources, respectively, in response to control signals; and
a control system coupled to the lighting panel and to the photosensor and configured to provide a feedback loop from the photosensor to the lighting panel by sampling the photosensor output, and, responsive to the photosensor output samples, providing the control signals to the first and second current sources to adjust an average current supplied to at least the first and second pulsed LED light sources. - View Dependent Claims (34, 35, 36)
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37. An LCD backlight for an LCD display having a visible area with a diagonal size greater than 17″
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a plurality of strings of red, green and blue LEDs arranged in a two-dimensional surface that is substantially parallel to a display surface of the LCD display, wherein the two-dimensional surface has an area greater than about 30% of the visible area of the LCD display;
wherein an average power dissipated by the LEDs, is less than about 0.3 Watts per square inch over the two-dimensional surface; and
wherein an average luminance of the LCD backlight at maximum brightness adjustment is greater than 200 Nit at 22 degrees C. ambient temperature when set to a white point with a correlated color temperature of between 4000k and 8000k. - View Dependent Claims (38, 39, 40, 41, 42)
- , the LCD backlight comprising;
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43. An LCD backlight system, comprising:
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a lighting panel comprising a plurality of tiles, each of the plurality of tiles having thereon a plurality red, green and blue LED chips arranged in RGB clusters on a substrate, wherein the LED chips in the lighting panel are electrically connected into a plurality of red, green and blue LED strings;
a plurality of constant current sources, each configured to energize a different LED string in response to a corresponding control signal;
wherein an average luminance of the lighting panel at maximum brightness adjustment is greater than 220 Nit at 22 deg C. ambient temperature when set to a white point with a correlated color temperature of between 4000k and 8000k. - View Dependent Claims (44)
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45. A method of operating a lighting panel including first and second strings of solid state lighting devices configured to emit light having first and second dominant wavelengths, respectively, the method comprising:
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supplying a first pulsed drive current the first string, the first drive current having a first pulse width at a pulse repetition rate;
supplying a second pulsed drive current the second string, the second drive current having a second pulse width at the pulse repetition rate;
sensing a light output from the lighting panel; and
adjusting the first pulse width in response to the sensed light output.
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46-64. -64. (canceled)
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65. A lighting panel system, comprising:
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a lighting panel including a plurality of bar assemblies;
at least a first string of solid state lighting devices configured to emit light at a first dominant wavelength and a second string of solid state lighting devices configured to emit light at a second dominant wavelength, different from the first dominant wavelength, in each of the plurality of bar assemblies;
a plurality of current supply circuits configured to supply an on-state drive current to a corresponding string in response to a respective one of a plurality of control signals;
a plurality of photosensors arranged to receive light from the first and second strings of a corresponding bar assembly;
a control system configured to receive an output signal from the photosensors and to adjust the control signals responsive to the output signals of the photosensors to thereby adjust an average current supplied to the strings by the current supply circuits.
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66-67. -67. (canceled)
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68. A lighting panel system, comprising:
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a lighting panel including a plurality of bar assemblies;
at least a first string of solid state lighting devices configured to emit light at a first dominant wavelength and a second string of solid state lighting devices configured to emit light at a second dominant wavelength, different from the first dominant wavelength, in each of the plurality of bar assemblies;
a plurality of current supply circuits configured to supply an on-state drive current to a corresponding string upon receipt of a respective one of a plurality of control signals;
a photosensor arranged to receive light from each of the bar assemblies; and
a control system configured to receive an output signal from the photosensor and to adjust the control signals responsive to the output signal of the photosensors to thereby adjust an average current supplied to the strings by the current supply circuits.
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69-71. -71. (canceled)
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72. A method of calibrating a lighting panel comprising a plurality of segments, each of said segments configured to emit a first color light and a second color light in response to pulse width modulated control signals applied thereto, the method comprising:
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for each color, measuring a luminance of each segment at a first duty cycle;
for each color, calculating a nominal luminance ratio comprising a ratio of a total luminance of each color divided by a total luminance of the lighting panel;
for each segment, calculating a luminance ratio for each color comprising a ratio of a total luminance of a color of a respective segment to a total luminance of the respective segment;
determining a variation of illuminance ratios from the nominal illuminance ratio for each segment and for each color; and
in response to at least one variation of illuminance ratios from the nominal illuminance ratio exceeding a threshold, adjusting a duty cycle of at least one color of at least one segment to reduce the at least one variation of illuminance ratios from the nominal illuminance ratio.
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73-79. -79. (canceled)
Specification