Display device control based on integrated ambient light detection and lighting source characteristics

• US 8,384,003 B2
• Filed: 05/04/2011
• Issued: 02/26/2013
• Est. Priority Date: 12/13/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Gardner, William Bryson Jr.
• Primary Examiner(s): Ko, Tony
• Application Number:
  US13/100,757
• Publication Number:
  US 20110204793A1
• Time in Patent Office: 664 Days
• Field of Search: 250/225, 250/214.AL, 348/308, 345/7, 345/102
• US Class Current: 250/205
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• 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 3/3225 using an active matrix
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: H05B 47/165 following a pre-assigned programmed sequence; Logic control [LC]

Abstract

Systems and methods are provided for a display device including one or more methods for modifying the display brightness by automatically adapting to ambient lighting conditions.

Claims

1. A transmissive display comprising:

an integrated light source for illuminating the transmissive display by emitting light during a first illumination period,

an integrated light sensor for generating a sensor signal based on an amount of light present during a first sensing interval after the first illumination period, and

a processor for receiving the sensor signal and controlling the light source during a second illumination period after the sensing interval based at least in part on the sensor signal, wherein the first illumination period includes a power period, during which a controller applies power to the integrated light source, and a delay period, and wherein the delay period is determined based on an illumination decay characteristic of at least one lighting element of the integrated light source.

2. The display of claim 1, wherein a path for ambient light to reach the integrated light sensor includes a path via the transmissive display.

3. The display of claim 1, wherein the at least one lighting element includes a light emitting diode (LED).

4. The display of claim 3, wherein the illumination decay characteristic of the LED is based on at least one of physical properties of the LED, an age of the LED, an amount of power applied to the LED during the power period, and a duration of the power period.

5. The display of claim 1, wherein the sensing interval begins after the delay period ends.

6. The display of claim 1, wherein the delay period associated with the first illumination period is preselected.

7. The display of claim 1, wherein the delay period associated with the first illumination period is determined based on an amount of time required after the power period for the illumination level to reach a threshold level.

8. The display of claim 1, wherein controlling includes adjusting an amount of power applied to at least one lighting element of the integrated light source to adjust an illumination intensity of the display.

9. The display of claim 1, wherein the integrated light source includes an array of lighting elements.

10. A transmissive display comprising:

an integrated light source for illuminating the transmissive display by emitting light during a first illumination period,

an integrated light sensor for generating a sensor signal based on an amount of light present during a first sensing interval after the first illumination period, and

a processor for receiving the sensor signal and controlling the light source during a second illumination period after the sensing interval based at least in part on the sensor signal, wherein an illumination period includes a power period, during which a controller applies power to the integrated light source, and a delay period, and wherein controlling includes adjusting a duration of the power period of the second illumination period to adjust an illumination intensity of the display.

11. A method for automatically controlling a level of illumination for a transmissive display comprising:

illuminating the transmissive display by emitting light from a light source during a first illumination period,

generating a sensor signal based on an amount of light present at an integrated light sensor during a sensing interval after the first illumination period, and

controlling the emitting of light during a second illumination period after the sensing interval based at least in part on the sensor signal, the controlling including adjusting the duration of a power period.

12. A display device comprising:

a transmissive display assembly including;

a light source for emitting light over a first period of time to illuminate a portion of the display, wherein the first period of time comprises an illumination decay period during which power is not applied to the light source,

a sensor for sensing ambient light over a second period of time, wherein the second period of time begins a predetermined duration of time after the illumination decay period begins, and

a processor for controlling the emitting of light from the light source over the first period of time and the sensing of ambient light over the second period of time.

13. The device of claim 12, wherein the first period of time includes a period when the emitted light is above a predetermined threshold.

14. The device of claim 13, wherein the second period of time includes a period when the emitted light is at or below the predetermined threshold.

15. The device of claim 14, wherein the duration of a subsequent third period of time is determined, at least in part, by the amount of ambient light sensed during the second period of time.

16. The device of claim 15, wherein the duration of the third period of time is determined, at least in part, by the amount of light emitted during the first period of time.

17. The device of claim 12, wherein the transmissive display assembly includes of a liquid crystal display.

18. The device of claim 12, wherein the light source is comprised of an array of white light emitting diodes.

19. The device of claim 12, wherein the light sensor is comprised of at least one of a photodiode and a phototransistor that is sensitive to white light.

20. The device of claim 12, wherein the light source is comprised of an array of red, blue, and green light emitting diodes.

21. The device of claim 20, wherein the sensor is comprised of at least one of a group of photodiodes and a group of phototransistors that are sensitive to the frequencies of red, blue, and green light emitted by the light emitting diodes.

22. A transmissive display comprising:

a sensor for generating a sensor signal based on an amount of light present at its receptor,

a light source for illuminating the transmissive display, and

a processor for repeatedly performing the following i) applying power to the light source during a first period of time, ii) waiting a second period of time for the emitted light intensity from the light source to decay below a light sensor interference level, and iii) sensing the ambient light passing through the transmissive display during a third period of time.

23. A method for automatically controlling the level of illumination for a transmissive display based on measured ambient light levels comprising the steps of:

A. enabling the light source to emit light and measuring the intensity of the light emitted by the light source during a first time period,

B. inhibiting the light source from emitting light and measuring the intensity of ambient light during a second time period,

C. processing the light measurements from the first time period and second time period to determine the durations of the first time period and second time period for a subsequent iteration of steps A-C, and

D. repeating steps A-C at least once.