White point adjustment for multicolor keyboard backlight

• US 8,915,633 B2
• Filed: 10/08/2012
• Issued: 12/23/2014
• Est. Priority Date: 06/01/2009
• Status: Expired due to Fees

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Pance, Aleksandar, Kerr, Duncan, Bilbrey, Brett, Slack, Brandon Dean, Cutler, Reese T.
• Primary Examiner(s): CARTER, WILLIAM JOSEPH
• Application Number:
  US13/647,363
• Publication Number:
  US 20130093330A1
• Time in Patent Office: 806 Days
• Field of Search: 362600-632
• US Class Current: 362/602
• CPC Class Codes: G02B 6/0001 specially adapted for lighting devices or systems lighting or signalling on vehicles using light guides B60Q1/00; lighting devices for vehicle dashboards B60Q3/10; lighting devices for vehicle interior using light guides B60Q3/62; lighting devices mounted on the vehicle rear part using light guides F21S43/235; measuring arrangements having light conducting pointers G01D13/265; illumination of liquid crystal displays G02F1/1336; illuminated signs G09F13/00
• CPC Class Codes: H01H 2219/038 ambient light dependent
• CPC Class Codes: H01H 2219/039 Selective or different modes of illumination
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 47/165 following a pre-assigned programmed sequence; Logic control [LC]

Abstract

There are provided systems, devices and methods for operating a light source to match a white point of ambient light. In one embodiment, a light control system is provided. The light control system includes a light source and a light sensor. The light sensor is configured to operate in conjunction with the light source to provide a visual effect. A controller is electrically coupled to the light source and the light sensor and configured to determine the intensity and color of light to which the light sensor is exposed and dynamically adjust the output of the light source to match the determined intensity and color of light to which the light sensor is exposed.

Claims

1. A method of operating a back lighting system of a keyboard comprising:

actuating a light sensor to sense ambient light through at least one key on said keyboard;

determining a white point of the sensed ambient light;

determining a constant contrast ratio of the sensed ambient light and a non-illuminated surface;

actuating a multicolor light source to dynamically provide a desired white point output through a light distribution network associated with said at least one key, said desired white point output approximately equal to the determined white point of the sensed ambient light; and

adjusting a brightness output of the light source based on the constant contrast ratio, said constant contrast ratio including a ratio of the sensed ambient light to a brightness of said light source.

2. The method of claim 1 comprising time division multiplexing actuation of the light sensor and the light source.

3. The method of claim 1, wherein actuating a multicolor light source comprises pulse width modulating an input to the multicolor light source.

4. The method of claim 1 wherein determining the white point of sensed light comprises determining an intensity of the sensed light at discrete wavelength ranges.

5. The method of claim 4 wherein the discrete wavelength ranges comprise a wavelength range that includes red light, a wavelength range that includes green light and a wavelength range that includes blue light.

6. A backlit keyboard comprising:

one or more light sources comprising independently operable red LEDs, green LEDs and blue LEDs;

one or more light distribution networks to distribute light to one or more keys of the keyboard, the keys comprising;

a transparent portion through which light emitted from the one or more light sources may pass; and

an opaque surface adjacent the transparent portion;

one or more light sensors configured to sense ambient light through said transparent portion; and

a controller configured to determine intensity and color of the sensed ambient light and actuate the red, green and blue LEDs to create an output light having a color and intensity approximately equal to the ambient light reflected from the opaque surface and

wherein intensity includes a constant contrast ratio, said constant contrast ratio including a ratio of the sensed ambient light to a brightness output of said light sources.

7. The backlit keyboard of claim 6, wherein:

the controller references a calibration table to determine a white point output for the light source; and

the controller uses the white point output to dynamically adjust the output of the multicolor light source.

8. The backlit keyboard of claim 6, wherein:

the calibration table includes a plurality of entries; and

each of the plurality of entries comprises a red, green and blue value.

9. The backlit keyboard of claim 8, wherein the controller actuates the red, green and blue LEDs according to the red, green and blue values retrieved from the calibration table.

10. The backlit keyboard of claim 6, wherein the employs the white point output to dynamically adjust a non-white output of the multicolor light source.

11. The backlit keyboard of claim 6, wherein the one or more lights sensors are located under one or more keycaps of the keyboard.

12. The backlit keyboard of claim 6, wherein the one or more light sensors comprise one or more narrowband photosensitive devices.

13. The backlit keyboard of claim 6, wherein the one or more light sensors comprise:

at least one sensor configured to sense a red component of the ambient light;

at least one sensor configured to sense a blue component of the ambient light; and

at least one sensor configured to sense a green component of the ambient light.

14. The backlit keyboard of claim 13, wherein the independently operable red LEDs, green LEDs and blue LEDs are operated to match a sensed intensity level of their respective component of the ambient light.

15. The backlit keyboard of claim 6, wherein the one or more light sensors comprise at least one broadband photosensitive device.

16. The backlit keyboard of claim 6, wherein the controller is configured to:

select a scaling parameter based on the sensed ambient light; and

scale the one or more light sources based on the scaling parameter.

17. The backlit keyboard of claim 16, wherein the scaling parameter comprises a power input for each of the independently operable red LEDs, green LEDs and blue LEDs.

18. The backlit keyboard of claim 17, wherein the power input comprises a pulse width modulated signal.

19. The backlit keyboard of claim 6, wherein the one or more light sensors and one or more light sources are operated in a time-division multiplexed manner.

20. The backlit keyboard of claim 6, wherein the one or more light sources and the one or more light sensors are arranged in an array pattern.