IP, Reports & Roadmaps | Nov 20, 2006

Systems and methods for controlling illumination sources

Abstract:
Provided are methods and systems for controlling the conversion of data inputs to a computer-based light system into lighting control signals. The methods and systems include facilities for controlling a nonlinear relationship between data inputs and lighting control signal ouputs. The nonlinear relationship may be programmed to account for varying responses of the viewer of a light source to different light source intensities.

Background of the invention

1. Field of the Invention
This disclosure relates to the field of illumination, and more particularly to the field of illumination sources controlled by a computer.

2. Description of the Related Art
LED lighting systems are used in a variety of applications to provide light, including for illumination, display and indication. One method of operating an LED in these systems is through pulse width modulation (PWM). That is, the current through the LED is fixed at a desired level and the duration the LED is activated varies to generate the appearance that the LED is dimming or increasing in intensity. The human eye integrates light it receives, and if the LED is on for a very short period of time, the LED appears dim even though the LED was operated at its optimum current. Another method of operating LEDs is through analog techniques where the amplitude of either the voltage or the current is modulated to change the light output of the LEDs. There are other techniques for operating LEDs, for example amplitude modulation of a pulsed signal or other techniques for modulating the power dissipated by the LED per unit of time. Certain techniques for the computer control of LEDs to generate illumination are disclosed in U.S. Pat. No. 6,016,038, which is hereby incorporated by reference.

One of the problems with changing the apparent or actual light output of an LED from a low light level to a higher light level is that the output changes may appear as stepped function rather than a smooth transition. This is common to other light sources, besides LEDs, as well. This is because the eye is highly sensitive to discrete changes in light output at low light levels. When the light is changed from one low light output level to another low light output level, the eye perceives the change as stepped. It would be useful to provide a lighting system that reduced the apparent stepped transition in light output from such a lighting system.
 

Brief summary of the invention

Provided herein are methods and systems for providing control signals for lights and light systems. The methods and systems include methods and systems for accessing a control module for generating an output control signal to control the output of a light, providing a conversion module for converting a data input to the output control signal, determining the response of a viewer to different levels of output of the light, and converting data inputs to output control signals in a nonlinear relationship to account for the response of a viewer to different levels of output of the light.

The methods and systems can include relationships in which the changes in the output control signal are smaller a low levels of light output and larger at higher levels of light output and methods and systems wherein the ratio of the output control signal to the data input increases continuously throughout the intensity range of the light.

The relationship between the data input and the output control signal can be a continuously increasing relationship. The relationship between the data input and the output control signal can be based on a function, such as an exponential function, a quadratic function, a squared function, a cubed function or other function.

The light may be an LED, and the ouput control signal can be a pulse width modulation (PWM) signal.

The ratio of the output control signal to the data input can increase continuously throughout the intensity range of the light.

The relationship between the data input and the output control signal can comprise multiple relationships, such as two linear relationships of different slopes or a linear relationship and a non-linear relationship. Where two linear relationships are used, one can apply to lower levels of data input with a lower slope than a second relationship that applies to higher levels of data input and that has a higher slope. Where there is a linear relationship and a nonlinear relationship, they can apply to different data ranges, and the nonlinear relationship can be based on a function, such as a an exponential function, a quadratic function, a squared function, a cubed function, or any other function.

The relationships used herein can account for the responses viewers to lights and illumination sources, such as those having LEDs of colors of different frequency ranges, such as red, green, blue, white, UV, IR, and amber LEDs. In embodiments the viewer response can be calculated based on reflected illumination, such as that reflected from a white surface, a wall, a colored surface, a mirror, a lens, or any other element. The relationships can be used to account for viewer responses to color-mixed light ouput. The color-mixed ouput can come from LEDs, such as red, green, blue, white, UV, IR, and/or amber LEDs.

The methods and systems disclosed herein also include methods and systems for providing a lighting control signal and may include methods and systems for providing a processor, providing memory, providing a light, providing a data input, providing a user interface, and using the processor to access a table stored in the memory to determine a control signal for the light, wherein the processor accesses the table to determine the control signal and wherein the table stores a nonlinear relationship between the data input and the control signal. The table can store a function that defines the nonlinear relationship. A user interface can allow a user to modify a parameter of the function, such as a PWM parameter and/or a scaling factor. In embodiments the user interface can allow a user to modify the table or select one or more tables from a plurality of tables. A function can define the relationship between the data input and the control signal, and can cause the ouput signal to increase continually in increasing amounts throughout the range of the data input.

Also provided herein are methods and systems of providing a conversion module having a processor for applying a nonlinear relationship to convert a data input to an ouput control signal for the light to account for the response of a viewer of the light to varying light levels.

Claims


1. A system to control a light, the system comprising: a user interface to control at least one nonlinear relationship between a data input and an output control signal for the light; and a conversion module that converts the data input to the output control signal using the at least one nonlinear relationship, wherein the at least one nonlinear relationship accounts for a response of a viewer to different intensities of the light.
2. The system of claim 1, further comprising a memory where a table is stored, the table comprising the at least one nonlinear relationship.
3. The system of claim 1, wherein the at least one nonlinear relationship comprises a function selected from a group consisting of an exponential function, a squared function, and a cubed function.
4. The system of claim 1, wherein the at least one nonlinear relationship comprises: a first linear relationship with a first slope; and a second linear relationship with a second slope that is different than the first slope.
5. The system of claim 4, wherein the first slope of the first linear relationship and the second slope of the second linear relationship are non-zero.
6. The system of claim 1, wherein the at least one nonlinear relationship includes a plurality of selectable nonlinear relationships, wherein the user interface is configured to select one nonlinear relationship of the plurality of selectable nonlinear relationships, and wherein the conversion module converts the data input to the output control signal using the selected one nonlinear relationship.
7. The system of claim 1, wherein the at least one nonlinear relationship accounts for the response of the viewer to reflected illumination.
8. The system of claim 1, wherein the at least one nonlinear relationship is continuously increasing.
9. The system of claim 1, wherein the user interface is adapted to modify the at least one nonlinear relationship, and wherein the conversion module converts the data input to the output control signal using the modified at least one nonlinear relationship.
10. The system of claim 1, wherein the output control signal is a pulse width modulated signal.
11. The system of claim 2, wherein the user interface is adapted to modify the table, and wherein the conversion module converts the data input to the output control signal using the modified table.
12. A method of controlling a light, the method comprising steps of: determining a response of a viewer to a change in an intensity of the light; operating the light based on a nonlinear relationship between data input steps and an output control signal that accounts for the response of the viewer; and adjusting the nonlinear relationship.
13. The method of claim 12, wherein the step of adjusting the nonlinear relationship further comprises a step of employing a user interface.
14. The method of claim 12, wherein the step of adjusting the nonlinear relationship occurs while the light is viewed by the viewer.
15. The method of claim 14, wherein the response of the viewer comprises a response to reflected illumination.
16. The method of claim 14, further comprising a step of storing the nonlinear relationship in a memory.
17. The method of claim 16, wherein the memory is included in a conversion module.
18. A method of controlling a light, the method comprising steps of: employing a multi-bit system; operating the light based on a nonlinear relationship between data input steps and an output control signal that accounts for a response of a viewer; and scaling the nonlinear relationship so as to minimize a change in intensity between adjacent data input steps corresponding to low light intensities and so as to maximize the change in intensity between adjacent data input steps corresponding to high light intensities, wherein the multi-bit system is a first size having a first quantity of bits, and wherein a range of adjustment of the light corresponds to a range of adjustment provided by a linear system employing a multi-bit system that has a second size having a second quantity of bits that is greater than the first quantity of bits.
19. The method of claim 18, wherein the second quantity of bits is at least 50% greater than the first quantity of bits.
20. The method of claim 19, wherein the range of adjustment is a range of intensity of the light.
21. An illumination apparatus, comprising: at least one first LED configured to generate at least first radiation having a first spectrum, wherein the first radiation, when generated, provides illumination in an environment; and at least one controller coupled to the at least one first LED to control a first intensity of the first radiation, the at least one controller further configured to: receive a first X-bit lighting command representing a first value within a first control range for the first intensity; convert the first X-bit lighting command to a first Y-bit lighting command representing a second value within the first control range for the first intensity, wherein X and Y are different integers, and wherein the second value in the first control range is related to the first value in the first control range based on a non-linear relationship; and control the first intensity of the first radiation based at least in part on the second value in the first control range.
22. The apparatus of claim 21, further comprising: at least one second LED configured to generate at least second radiation having a second spectrum different than the first spectrum, wherein the first radiation and the second radiation, when generated, provide the illumination in the environment, and wherein the at least one controller is further configured to control a second intensity of the second radiation.
23. The apparatus of claim 22, wherein X is less than Y.
24. The apparatus of claim 23, wherein X is eight and wherein Y is at least fourteen.
25. The apparatus of claim 22, further comprising a memory to store at least one representation of the non-linear relationship, wherein the at least one representation includes at least one of a function and a table of values, and wherein the at least one controller utilizes the at least one representation to convert the first X-bit lighting command to the first Y-bit lighting command.
26. The apparatus of claim 25, wherein the non-linear relationship is a continuously increasing relationship.
27. The apparatus of claim 25, wherein the non-linear relationship includes at least two linear relationships having respective different slopes.
28. The apparatus of claim 25, wherein the non-linear relationship includes at least one linear portion over a first part of the first control range and at least one nonlinear portion over a second part of the first control range.
29. The apparatus of claim 25, wherein the non-linear relationship includes one of an exponential relationship, a quadratic relationship, and a cubed relationship.
30. The apparatus of claim 25, wherein the non-linear relationship has a relatively smaller slope for relatively smaller first values and a relatively higher slope for relatively higher first values.
31. The apparatus of claim 21, wherein the at least one first LED includes at least one white LED.
32. The apparatus of claim 22, wherein the at least one controller is further configured to: receive a second X-bit lighting command representing a first value within a second control range for the second intensity; convert the second X-bit lighting command to a second Y-bit lighting command representing a second value within the second control range for the second intensity, wherein the second value in the second control range is related to the first value in the second control range based on the non-linear relationship; and control the second intensity of the second radiation based at least in part on the second value in the second control range.
33. The apparatus of claim 32, wherein the at least one first LED includes at least one white LED.
34. The apparatus of claim 33, wherein the illumination is essentially white, and wherein the at least one controller is configured to control a color temperature of the illumination based at least in part on the second value in the first control range and the second value in the second control range.

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