Method for sensing light being incident on an electronic device

Patent metadata

Field	Value
Publication number	US-10950187-B2
Application number	US-201816489947-A
Country	US
Kind code	B2
Filing date	Feb 7, 2018
Priority date	Mar 2, 2017
Publication date	Mar 16, 2021
Grant date	Mar 16, 2021

Abstract

A method is suggested for sensing light being incident on an electronic device. The electronic device comprises a display and a light sensor arrangement mounted behind the display such as to receive incident light through the display. The method comprises periodically switching the display on and off depending on a control signal, wherein a period is defined by a succession of an on-state and an off-state of the display. A sensor signal is generated by integrating the incident light by means of the light sensor arrangement for a total integration time comprising a number of periods. A first signal count is determined from the sensor signal being indicative of an amount of integrated incident light during an on-state. A second signal count is determined from the sensor signal being indicative of an amount of integrated incident light during an off-state. A third signal count is determined from the sensor signal being indicative of an amount of integrated incident light during the total integration time. Finally, an ambient light level is determined depending on the first, second and third signal counts.

First claim

The invention claimed is:

1. A method for sensing light being incident on an electronic device, the electronic device comprising a display and a light sensor arrangement mounted behind the display such as to receive incident light through the display, the method comprising the steps of:
periodically switching the display on and off depending on a control signal, wherein a period of said periodical switching is defined by the time of a succession of an on-state and an off-state of the display,
generating a sensor signal by integrating the incident light by means of the light sensor arrangement for a total integration time comprising a plurality of said periods of periodical switching,
for at least some on-states included in the total integration time, determining a respective first signal count from the sensor signal being indicative of an amount of integrated incident light during the corresponding on-state,
for at least some off-states included in the total integration time, determining a respective second signal count from the sensor signal being indicative of an amount of integrated incident light during the corresponding off-state,
determining a display light level comprising subtracting the sum of all determined second signal counts from the sum of all determined first signal counts,
determining a third signal count from the sensor signal being indicative of an amount of integrated incident light during the total integration time, and
determining an ambient light level depending on the first, second and third signal counts by subtracting the display light level from the third signal count.

2. The method according to claim 1 , wherein the sensor signal is generated by continuously integrating the incident light for the duration of the total integration time.

3. The method according claim 1 , wherein the first and second signal counts are determined by tapping the sensor signal for a predetermined time during integrating the incident light.

4. The method according to claim 1 , wherein the first and second signal counts are determined from the sensor signal integrated during at least one period.

5. The method according to claim 1 , wherein for each period of successive on- and off-states set of first signal count and second signal count are determined, respectively.

6. The method according to claim 1 , wherein
at least one display level is determined from at least one first count and at least one second count, wherein the display level is indicative of an amount of integrated incident light emitted by the display during at least one period,
an integral level is determined from the third signal count, wherein the integral level is indicative of a combined amount of integrated incident light emitted by the display during the total integration time and of incident ambient light received during the total integration time, and
the ambient light level is determined from the integral level and the at least one display level.

7. The method according to claim 1 , wherein
a single display level is determined from a number of first counts and a number of second counts, wherein the display level is indicative of an amount of integrated incident light emitted by the display during the total integration time, and
the ambient light level is determined from the integral level and the display level.

8. The method according to claim 1 , wherein the duration of a period is determined by a picture refresh signal of the display.

9. The method according to claim 8 , wherein determining the first and second signal counts is synchronized to the picture refresh signal.

10. The method according to claim 1 , wherein a duration of an on-state with respect to a duration of an off-state is determined by a duty cycle of the display.

11. The method according to claim 10 , wherein the duty cycle is constant for the duration of the total integration time.

12. The method according to claim 1 , wherein ambient light level is determined depending on weighted first, second and third signal counts.

13. The method according to claim 12 , wherein the first, second and third signal counts are weighted by weighting factors determined by the duty cycle and/or the picture refresh signal.

14. The method according to claim 1 , wherein the first and second signal counts are determined in close temporal succession, or the first and second signal counts are determined within a time period given by 15%, 10%, 5%, or 1% of the duration of a period.

15. The method according to claim 1 , wherein
the light sensor arrangement comprises a single light sensor and the first, second and third signal counts are determined from the single light sensor.

16. A method for sensing light being incident on an electronic device, the electronic device comprising a display and a light sensor arrangement mounted behind the display such as to receive incident light through the display, the method comprising the steps of:
periodically switching the display on and off depending on a control signal, wherein a period is defined by a succession of an on-state and an off-state of the display,
generating a sensor signal by integrating the incident light by means of the light sensor arrangement for a total integration time comprising a number of periods,
determining a first signal count from the sensor signal being indicative of an amount of integrated incident light during an on-state,
determining a second signal count from the sensor signal being indicative of an amount of integrated incident light during an off-state,
determining a third signal count from the sensor signal being indicative of an amount of integrated incident light during the total integration time, and
determining an ambient light level depending on the first, second and third signal counts; and
wherein the first and second signal counts are determined in close temporal succession, or the first and second signal counts are determined within a time period given by 15%, 10%, 5%, or 1% of the duration of a period.

17. A method for sensing light being incident on an electronic device, the electronic device comprising a display and a light sensor arrangement mounted behind the display such as to receive incident light through the display, the method comprising the steps of:
periodically switching the display on and off depending on a control signal, wherein a period is defined by a succession of an on-state and an off-state of the display,
generating a sensor signal by integrating the incident light by means of the light sensor arrangement for a total integration time comprising a number of periods,
determining a first signal count from the sensor signal being indicative of an amount of integrated incident light during an on-state,
determining a second signal count from the sensor signal being indicative of an amount of integrated incident light during an off-state,
determining a third signal count from the sensor signal being indicative of an amount of integrated incident light during the total integration time, and
determining an ambient light level depending on the first, second and third signal counts; and
wherein ambient light level is determined depending on weighted first, second and third signal counts; and
wherein the first, second and third signal counts are weighted by weighting factors determined by the duty cycle and/or the picture refresh signal.

Assignees

• Ams Ag

Inventors

• Kriebernegg Josef
• Greimel-Rechling Bernhard
• Lenhard Herbert
• Bliem Peter
• Lechner Joachim
• Halper Christian
• Hoerbinger Manuel

Classifications

• G09G2320/0626

  for control of overall brightness · CPC title

• G09G2310/0237

  Switching ON and OFF the backlight within one frame · CPC title

• G09G2360/144

  the light being ambient light · CPC title

• G09G3/3406 Primary

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

• G09G2320/0247

  Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes · CPC title