Systems and methods for controlling light sources

• US 8,937,443 B2
• Filed: 04/08/2014
• Issued: 01/20/2015
• Est. Priority Date: 02/10/2006
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Saccomanno, Robert J.
• Primary Examiner(s): VU, JIMMY T
• Application Number:
  US14/248,239
• Publication Number:
  US 20140203711A1
• Time in Patent Office: 287 Days
• Field of Search: 315/185.R, 315/209.R, 315/210, 315/291, 315/307, 315/308, 315/312, 362/555, 362/222, 362/223, 362/249.02
• US Class Current: 315/291
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/12 Test circuits or failure detection circuits included in a display system, as permanent part thereof
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices

Abstract

A system for controlling a set of light sources may include a set of light sources, at least one optical conduit arranged relative to the set of light sources so as to collect excess light from the set of light sources, and at least one sensor coupled to the optical conduit and configured to sense light collected by the optical conduit. The system may also include a controller configured to control the emittance of the set of light sources based on the light sensed by the sensor. A method for controlling a set of light sources may comprise individually varying power supplied to at least some of the light sources in an imperceptible manner, sensing light emitted by a light source for which the power has been varied, and controlling the emittance of the set of light sources based on the sensed light.

Claims

1. A method for controlling light output of an array comprising a plurality of series-connected of light sources by a controller while maintaining a desired operating emittance of the array, each light of the array having a shunt switch, the method comprising:

energizing the array of series-connected plurality of light sources by applying a current necessary to generate for the desired operating emittance;

during a first time period, closing the shunt switch of a light source of the plurality of light sources, wherein the light source is extinguished;

sampling the remaining light of the array by an optical sensor during the first time period and during a second time period when the shunt switch is de-energized;

determining a difference in emittance between the first and second time periods;

comparing the difference in emittance to a luminance value stored in a memory associated with the shunted light source; and

subsequently controlling the operation of the shunt switch based on the comparison, wherein the subsequent controlling produces the desired operating emittance of the array.

2. The method of claim 1, wherein the first time period is less than a time period of a flicker frequency.

3. The method of claim 1, wherein a loss of light from the extinguishment of the light source is imperceptible by humans.

4. The method of claim 1, wherein the plurality of series-connected of light sources are selected from a group consisting of:

light emitting diodes, organic light emitting diodes, fluorescent lights, incandescent lights, and an liquid crystal display pixel.

5. The method of claim 1, further comprising determining a temperature of the light source by a temperature sensor.

6. The method of claim 5, wherein the stored luminance value is adjusted for the temperature of the light source by the controller.

7. The method of claim 1, wherein each light source of the plurality is extinguished in sequence as the method is repeated in an iterative fashion.

9. The method of claim 1, wherein each light source of the plurality is pulsed in sequence as the method is repeated in an iterative fashion.

10. The method of claim 1, further comprising energizing the array of series-connected plurality of light sources before the pulsing step by applying a current necessary to generate for the desired operating emittance.

11. The method of claim 9, wherein a pulse is a ramp up in current.

12. The method of claim 1, wherein each light source of the plurality is pulsed in sequence and in a different color as the method is repeated in an iterative fashion.

8. A method for controlling light output of an array comprising a plurality of series-connected of light sources by a controller while maintaining a desired operating emittance of the array, the method comprising:

during a first time period, pulsing current to a light source, wherein the light source is pulsed at a higher emittance;

sampling the light of the array by an optical sensor during the first time period and during a second time period when the current is not increased;

determining a difference in luminance between the first and second time periods;

comparing the difference in luminance to an emittance value stored in a memory associated with the shunted light source; and

subsequently controlling the current based on the comparison, wherein the subsequent controlling produces the desired operating emittance of the array.

13. A method for controlling light output of an array comprising a plurality of series-connected of light sources by a controller while maintaining a desired operating emittance of the array, the method comprising:

during a first time period, ramping current to a light source

sampling the light of the array by an optical sensor during the first time period and during a second time period when the current is not increased;

determining a difference in emittance between the first and second time periods;

comparing the difference in emittance to a luminance value stored in a memory associated with the shunted light source; and

subsequently controlling the current based on the comparison, wherein the subsequent controlling produces the desired operating emittance of the array.

14. The method of claim 13, wherein the light source is ramped to one of a higher or lower luminance.