Backlight control for a portable computing device

• US 20060192748A1
• Filed: 02/28/2005
• Published: 08/31/2006
• Est. Priority Date: 02/28/2005
• Status: Active Grant

• Current Assignee: Blackberry Limited
• Original Assignee: Blackberry Limited
• Inventors: Robinson, James, Drader, Marc A., Lowles, Robert J.
• Granted Patent: US 8,269,715 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3265 Power saving in display device
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: H04M 1/22 Illumination; Arrangements for improving the visibility of characters on dials
• CPC Class Codes: H04M 2250/12 including a sensor for measuring a physical value, e.g. temperature or motion telephones including GPS signal receivers H04M2250/10
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

In a portable computing device that includes a backlit device having a variable-intensity backlight, a light sensor, and a light controller coupled to the light sensor and the backlight, a method for controlling the intensity of light produced by the backlight involves the steps of (1) with the ambient light sensor determining the ambient light level at the computing device; and (2) with the light controller automatically adjusting the intensity of light produced by the backlight in accordance with the determined light level.

Claims

1. A portable computing device comprising:

a display device having a variable-intensity backlight;

a light sensor for determining an ambient light level at the computing device; and

a light controller coupled to the display backlight and the light sensor for adjusting an intensity of light emitted by the display backlight in accordance with the measured ambient light intensity, the light controller being configured to set the intensity of light (i) to a first intensity when the determined light level is greater than a first threshold, (ii) to a second level less than the first intensity when the determined light level is not greater than the first threshold, and (iii) to a third intensity less than the second intensity when the determined light level is less than a second threshold,

the second threshold being less than the first threshold when the display device comprises a transmissive LCD display, the second threshold being not less than the first threshold when the display device comprises one of a reflective and a trans-reflective LCD display.

2. The portable computing device according to claim 1, wherein the light controller is configured to gradually reduce the set intensity after a period of inactivity at the computing device.

3. The portable computing device according to claim 2, wherein the display device comprises a transmissive LCD display, the first threshold is greater than a dusk illumination level, and the second threshold is intermediate the dusk illumination level and a night illumination level.

4. The portable computing device according to claim 3, wherein the first threshold is an illumination level corresponding to direct sunlight, and the first intensity is an intensity level in which the display backlight is overdriven.

5. The portable computing device according to claim 3, wherein the portable computing device includes a backlit data entry device, and the light controller is coupled to the data entry device and is configured to illuminate the data entry device at a first keyboard intensity when the determined light level is greater than the second threshold, and to otherwise illuminate the data entry device at a second keyboard intensity less than the first keyboard intensity.

6. The portable computing device according to claim 5, wherein the light controller is configured to illuminate the data entry device at a third keyboard intensity less than the second keyboard intensity when the determined light level is greater than the first threshold.

7. The portable computing device according to claim 2, wherein the display device comprises one of a reflective LCD display and a trans-reflective LCD display, the first threshold is intermediate a dusk illumination level and a night illumination level, and the second threshold is intermediate the dusk illumination level and a sunlight illumination level.

8. The portable computing device according to claim 7 wherein the portable computing device includes a backlit data entry device, and the light controller is coupled to the data entry device and is configured to illuminate the data entry device at a first keyboard intensity when the determined light level is greater than the first threshold, and to otherwise illuminate the data entry device at a second keyboard intensity less than the first keyboard intensity.

10. In a portable computing device that includes a backlit device having a variable-intensity backlight, a light sensor, and a light controller coupled to the light sensor and the display backlight, a method for controlling the intensity of light produced by the display backlight, comprising the steps of:

with the light sensor determining an intensity of ambient light at the computing device; and

with the light controller automatically adjusting an intensity of light produced by the display backlight in accordance with the determined ambient light intensity, the light intensity adjusting step comprising the steps of (i) setting the backlight intensity to a first intensity when the determined light level is greater than a first threshold, (ii) setting the backlight intensity to a second level less than the first intensity when the determined light level is not greater than the first threshold, and (iii) setting the backlight intensity to a third intensity less than the second intensity when the determined light level is less than a second threshold, the second threshold being less than the first threshold when the display device comprises a transmissive LCD display, the second threshold being not less than the first threshold when the display device comprises one of a reflective and a trans-reflective LCD display.

9. The portable computing device according to claim 10, wherein the light controller is configured to illuminate the data entry device at a third keyboard intensity less than the second keyboard intensity when the determined light level is greater than the second threshold.

11. The method according to claim 10, wherein the light intensity adjusting step further comprises gradually reducing the set intensity after a period of inactivity at the computing device.

12. The method according to claim 11, wherein the display device comprises a transmissive LCD display, the first threshold is intermediate a sunlight illumination level and a dusk illumination level, and the second threshold is intermediate the dusk illumination level and a night illumination level.

13. The method according to claim 12, wherein the first intensity is an intensity level in which the display backlight is overdriven.

14. The method according to claim 13, wherein the portable computing device includes a backlit data entry device, and the light intensity adjusting step comprises the steps of (i) illuminating the data entry device at a first keyboard intensity when the determined light level is greater than the second threshold, and (ii) otherwise illuminating the data entry device at a second keyboard intensity less than the first keyboard intensity.

15. The method according to claim 14, wherein the light intensity adjusting step further comprises the step of illuminating the data entry device at a third keyboard intensity less than the second keyboard intensity when the determined light level is greater than the first threshold.

16. The method according to claim 11, wherein the display device comprises a reflective LCD display, the first threshold is intermediate a dusk illumination level and a night illumination level, and the second threshold is intermediate the dusk illumination level and a sunlight illumination level.

17. The method according to claim 16, wherein the portable computing device includes a backlit data entry device, and the light intensity adjusting step comprises the steps of (i) illuminating the data entry device at a first keyboard intensity when the determined light level is greater than the first threshold, and (ii) otherwise illuminating the data entry device at a second keyboard intensity less than the first keyboard intensity.

18. The method according to claim 17, wherein the light intensity adjusting step further comprises the step of illuminating the data entry device at a third keyboard intensity less than the second keyboard intensity when the determined light level is greater than the second threshold.

19. The method according to claim 10, wherein one of the thresholds and/or intensities is user-configurable.

20. A computer-readable medium including computer processing instructions for a processing unit of a portable computing device, the portable computing device including a backlit display having a variable-intensity backlight, the computer processing instructions when executed by the processing unit causing the portable computing device to:

determine the ambient light level at the computing device; and

adjust the intensity of light produced by the backlight in accordance with determined light level, the light intensity adjusting step comprising the steps of (i) setting the backlight intensity to a first intensity when the determined light level is greater than a first threshold, (ii) setting the backlight intensity to a second level less than the first intensity when the determined light level is not greater than the first threshold, and (iii) setting the backlight intensity to a third intensity less than the second intensity when the determined light level is less than a second threshold,

the second threshold being less than the first threshold when the display device comprises a transmissive LCD display, the second threshold being not less than the first threshold when the display device comprises one of a reflective and a trans-reflective LCD display.