Ambient light sensor

Patent metadata

Field	Value
Publication number	US-11580901-B2
Application number	US-201917283793-A
Country	US
Kind code	B2
Filing date	Oct 11, 2019
Priority date	Oct 11, 2018
Publication date	Feb 14, 2023
Grant date	Feb 14, 2023

Abstract

Techniques are described for portable computing devices and other apparatus that include an ambient light sensor. The techniques can be particularly advantageous for situations in which the ambient light sensor is disposed behind a display screen of a host device such that ambient light detected by the sensor passes through the light emitting display before being detected by the sensor.

First claim

The invention claimed is:

1. An apparatus comprising:
a light emitting display screen;
an ambient light sensor disposed behind the display screen; and
a processor configured to receive, process and analyze signals from the ambient light sensor and to control a brightness of the display screen,
wherein the processor is configured to estimate a first amount of a light signal detected by the ambient light sensor that is attributable to light generated by the display screen, to subtract the first amount from a second amount so as to obtain an ambient light value, wherein the second amount represents a combined amount of light detected by the ambient light sensor, the combined amount including ambient light and light generated by the display screen, and wherein the processor is configured to control the brightness of the display screen based, at least in part, on the ambient light value.

2. The apparatus of claim 1 , wherein the display screen comprises an OLED-type display screen.

3. The apparatus of claim 1 , wherein the processor is configured to estimate the first amount of the light signal detected by the ambient light sensor based on a feature of a signal detected by the ambient light sensor, wherein the feature correlates with an amplitude of a light signal generated by the display screen.

4. The apparatus of claim 3 , wherein the feature of the signal detected by the ambient light sensor that correlates with the amplitude of the light signal generated by the display screen corresponds to a refresh period of the display screen.

5. The apparatus of claim 1 , wherein the processor is configured to extract a periodic signal from data received from the ambient light sensor, wherein an amplitude of the extracted periodic signal correlates with an amplitude of the light generated by the display screen, the processor further being configured to access a look-up table to estimate the amplitude of the light generated by the display screen based on the amplitude of the extracted periodic signal.

6. The apparatus of claim 5 , wherein the periodic signal has a period that is the same as a period of a refresh signal for the display screen.

7. The apparatus of claim 1 further comprising a cover glass, wherein the light emitting display screen is disposed behind the cover glass.

8. The apparatus of claim 1 wherein the ambient light sensor includes multiple light channels, the processor being configured to estimate, for each particular channel separately, a respective ambient light value by:
estimating a first respective amount of a light signal detected by the particular channel that is attributable to light generated by the display screen; and
subtracting the first respective amount from a second respective amount so as to obtain the respective ambient light value, wherein the second amount represents a combined amount of light detected by the particular channel, the combined amount including ambient light and light generated by the display screen,
wherein the processor is configured to control the brightness of the display screen based, at least in part, on a weighted average of the respective ambient light values for the channels.

9. The apparatus of claim 1 , wherein the processor is configured to report a lux value to the display screen, wherein the lux value is based at least in part on the ambient light value, the display screen being configured to respond in a predetermined manner based on the reported lux value.

10. The apparatus of claim 9 , wherein the display screen is configured to adjust its display light level in response to the reported lux value.

11. A method of controlling a brightness of a display screen, the method comprising:
detecting, in an ambient light sensor disposed behind the light emitting display, a combined amount of light including ambient light and light generated by the display screen,
receiving, in a processor, signals from the ambient light sensor, the received signals representing the combined amount of light;
estimating, by the processor, a first amount of a light signal detected by the ambient light sensor that is attributable to light generated by the display screen;
subtracting the first amount from a second amount so as to obtain an ambient light value, wherein the second amount represents the combined amount of light; and
adjusting the brightness of the display screen based, at least in part, on the ambient light value.

12. The method of claim 11 , wherein the display screen comprises an OLED-type display screen.

13. The method of claim 11 , wherein the estimating the first amount of the light signal detected by the ambient light sensor is based on a feature of a signal detected by the ambient light sensor, wherein the feature correlates with an amplitude of a light signal generated by the display screen.

14. The method of claim 13 , wherein the feature of the signal detected by the ambient light sensor that correlates with the amplitude of the light signal generated by the display screen corresponds to a refresh period of the display screen.

15. The method of claim 11 , further comprising extracting a periodic signal from data received from the ambient light sensor, wherein an amplitude of the extracted periodic signal correlates with an amplitude of the light generated by the display screen, the method further including accessing a look-up table to estimate the amplitude of the light generated by the display screen based on the amplitude of the extracted periodic signal.

16. The method of claim 15 , wherein the periodic signal has a period that is the same as a period of a refresh signal for the display screen.

17. The method of claim 11 , wherein the ambient light sensor includes multiple light channels, the method including estimating, for each particular channel separately, a respective ambient light value by:
estimating a first respective amount of a light signal detected by the particular channel that is attributable to light generated by the display screen; and
subtracting the first respective amount from a second respective amount so as to obtain the respective ambient light value, wherein the second amount represents a combined amount of light detected by the particular channel, the combined amount including ambient light and light generated by the display screen; and
controlling the brightness of the display screen based, at least in part, on a weighted average of the respective ambient light values for the channels.

18. The method of claim 11 including:
reporting a lux value that is based at least in part on the ambient light value; and
adjusting the light level of the display screen in response to the reported lux value.

19. The method of claim 11 , wherein the ambient light passes through the light emitting display before being detected by the ambient light sensor.

Assignees

• Ams Ag

Inventors

• Cogan Timothy
• Nelson Doug
• Hegde Pradeep
• Archibald James
• Paterson Drew
• Kelly George Richard
• Sin David Harlow

Classifications

• G09G2360/16

  Calculation or use of calculated indices related to luminance levels in display data · CPC title

• G09G2360/145

  the light originating from the display screen · CPC title

• G09G3/3406

  Control of illumination source (illumination devices structurally associated with liquid crystal cells G02F1/1336) · CPC title

• G09G2360/144

  the light being ambient light · CPC title

• G09G2320/0285

  using tables for spatial correction of display data · CPC title