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

• US 7,960,682 B2
• Filed: 12/13/2007
• Issued: 06/14/2011
• Est. Priority Date: 12/13/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Gardner, Bryson Jr.
• Primary Examiner(s): Ko; Tony
• Application Number:
  US12/002,120
• Publication Number:
  US 20090152445A1
• Time in Patent Office: 1,279 Days
• Field of Search: 250/225, 250/214.AL, 345/7, 348/308
• US Class Current: 250/225
• 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 method for controlling a display device comprising:

illuminating the display device by emitting light from a light emitting diode (“

LED”

) for a first period of time;

monitoring the emitted light for a delay period after the first period of time;

determining if the emitted light has decreased to a predetermined threshold;

in response to determining that the emitted light has decreased to the predetermined threshold, generating a signal with the LED associated with an amount of ambient light present during a second period of time after the delay period; and

controlling the emitting of light from the LED based on the signal during a third period of time after the second period of time.

2. The method of claim 1, wherein the controlling comprises:

adjusting a duration of time in which power is applied to the LED.

3. The method of claim 1, wherein the controlling comprises:

adjusting an amount of power applied to the LED.

4. The method of claim 1, wherein the delay period is determined based on at least one illumination decay characteristic of the LED.

5. The method of claim 4, wherein the at least one illumination decay characteristic is based on at least one of a physical property of the LED, an age of the LED, an amount of power applied to the LED during the first period of time, duration of the first period of time, and an ambient temperature.

6. The method of claim 5, wherein the at least one illumination delay characteristic is based at least in part on a duration of time in which power is applied to the LED during a previous cycle.

7. A system comprising:

a display;

a light emitting diode (“

LED”

) operable to;

emit light to illuminate the display during a first period of time; and

a processor operable to;

monitor the emitted light during a delay period after the first period of time;

determine if the emitted light has decreased to a predetermined threshold;

in response to determining that the emitted light has decreased to the predetermined threshold, configure the LED to generate a signal associated with an amount of ambient light present during a second period time after the delay period; and

control the emitting of the light by the LED based on the generated signal.

8. The system of claim 7, wherein:

the first period of time corresponds to a duty-cycle-on period associated with a pulse width modulated signal; and

the delay period and the second period of time correspond to a duty-cycle-off period associated with the pulse width modulated signal.

9. The system of claim 8, wherein the processor is further operable to control the duration of at least one of the duty-cycle-on period and the duty-cycle-off period based on the generated signal.

10. The system of claim 8, wherein the delay period is determined based on at least one illumination decay characteristic of the LED.

11. The system of claim 10, wherein the at least one illumination decay characteristic is based at least in part on the duty-cycle-on period and the duty-cycle-off period.

12. The system of claim 10, wherein the at least one illumination decay characteristic is based at least in part on a duty-cycle-on period and a duty-cycle-off period of a previous cycle.

13. The system of claim 7, further comprising a plurality of LEDs, and wherein the processor is further operable to provide power to a subset of the LED'"'"'s based on the generated signal.