Method and device for adjusting brightness of an optical touch panel

• US 8,797,296 B2
• Filed: 09/30/2010
• Issued: 08/05/2014
• Est. Priority Date: 09/30/2009
• Status: Active Grant

• Current Assignee: Toshiba Global Commerce Solutions Holdings Corporation (Toshiba Corporation)
• Original Assignee: Toshiba Global Commerce Solutions Holdings Corporation (Toshiba Corporation)
• Inventors: Hsieh, Tsung Hsuan, Hsuan, Wei Yi, Lee, Yi Sheng, Parsons, Robert David, Yang, Chia Lin
• Primary Examiner(s): SHAH, PRIYANK J
• Application Number:
  US12/895,123
• Publication Number:
  US 20110074737A1
• Time in Patent Office: 1,405 Days
• Field of Search: 345/102, 345175-178, 356614-624, 362 971- 974
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• 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: H05B 47/11 by determining the brightness or colour temperature of ambient light
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A method and device are provided for adjusting brightness of an optical touch panel. The optical touch panel comprises a microprocessor, a display module including a back light source, and an optical position detection device including optical transmitting devices and optical receiving devices. The method comprises detecting, via the optical receiving devices, a current ambient light level on the display module. The method further comprises generating, via the optical receiving devices, a current ambient light level signal indicative of the current ambient light level and transmitting the current ambient light level signal to the microprocessor. Furthermore, the method comprises adjusting, via the microprocessor, brightness of the back light source based on the current ambient light level signal.

Claims

1. A method for adjusting brightness of an optical touch panel, wherein said optical touch panel comprises a microprocessor, a display module including a back light source in one of a plurality of operation modes, and an optical position detection device including optical transmitting devices and optical receiving devices, and wherein said plurality of operation modes comprise an automatic calibration mode, said method comprising:

detecting, via said optical receiving devices, a current ambient light level on said display module;

generating, via said optical receiving devices, a current ambient light level signal indicative of said current ambient light level and transmitting said current ambient light level signal to said microprocessor; and

adjusting, via said microprocessor, brightness of said back light source based on said current ambient light level signal, wherein, when said back light source is in said automatic calibration mode, said adjusting comprises automatically calibrating said brightness of said back light source based on a predefined relation between said current ambient light level and said brightness of said back light source in response to a change in said current ambient light level.

2. The method of claim 1, wherein said back light source is in one of a plurality of operation modes, and wherein said optical touch panel is arranged on an electrical device.

3. The method of claim 2, wherein said plurality of operation modes comprise a low brightness mode, wherein in said low brightness mode said back light source is set to a first back light source brightness level and said electrical device is correspondingly set to a normal operation configuration in response to said current ambient light level being maintained at a first ambient light brightness level.

4. The method of claim 2, wherein said plurality of operation modes comprise a power saving mode, wherein in said power saving mode said back light source is switched off and said electrical device is correspondingly set to a sleep operation configuration in response to said current ambient light level being lower than a second ambient light brightness level, and wherein in said power saving mode said back light source is switched on to a second back light source brightness level and said electrical device is correspondingly set to a normal operation configuration in response to said current ambient light level being higher than said second ambient light brightness level.

5. The method of claim 2, wherein said plurality of operation modes comprise a normal mode in which said back light source is fixedly set to a third back light source brightness level.

6. The method of claim 1, further comprising:

obtaining a current gain G under a user-adjusted normal ambient light condition, wherein said current gain G is obtained by exposing said optical receiving devices to said user-adjusted normal ambient light condition for a first period of time, reading current gain values from said optical receiving devices during said first period of time, ranking said current gain values from high to low, and averaging an effective percentage range of said current gain values; and

wherein said current gain G is inversely proportional to said current ambient light level;

obtaining a minimum gain Gmin under a maximum ambient light condition, wherein said minimum gain Gmin is obtained by exposing said optical receiving devices to said maximum ambient light condition for a second period of time, reading minimum gain values from said optical receiving devices during said second period of time, ranking said minimum gain values from high to low, and averaging an effective percentage range of said minimum gain values; and

obtaining a maximum gain Gmax under a minimum ambient light condition, wherein said maximum gain Gmax is obtained by exposing said optical receiving devices to said minimum ambient light condition for a third period of time, reading maximum gain values from said optical receiving devices during said third period of time, ranking said maximum gain values from high to low, and averaging an effective percentage range of said maximum gain values.

7. The method of claim 6, further comprising switching off said optical transmitting devices and said optical receiving devices prior to obtaining said current gain G, said minimum gain Gmin, or said maximum gain Gmax.

8. The method of claim 6, further comprising switching off said back light source in response to said current gain G being larger than P % multiplied by said maximum gain Gmax, where P % is between 70% and 90%.

9. The method of claim 6, wherein said automatically calibrated brightness is calculated by:

(P2%×

Gmax−

G)/(P2%×

Gmax−

Gmin)=(P1%×

U−

X)/(P1%×

U−

P2%×

U), where U is user-defined brightness, 130%>

P1%>

105%, and 95%>

P2%>

70%.

10. The method of claim 1, wherein said predefined relation comprises a predefined brightness profile, wherein a first calibration brightness profile and a second calibration brightness profile are defined to envelop said predefined brightness profile;

wherein said first calibration brightness profile is a product of said predefined brightness profile multiplied by P1%, where 130%>

P1%>

105%; and

wherein said second calibration brightness profile is a product of said predefined brightness profile multiplied by P2%, where 95%>

P2%>

70%.

11. A device for adjusting brightness of an optical touch panel, said device comprising:

a display module comprising a display area and a back light source in one of a plurality of operation modes, said plurality of operation modes comprising an automatic calibration mode;

control circuitry electrically coupled to said display module; and

an optical position detection device coupled to said display module, said optical position detection device comprising optical transmitting devices and optical receiving devices;

wherein said optical receiving devices detect a current ambient light level on said display module, generate a current ambient light level signal indicative of said current ambient light level, and transmit said current ambient light level signal to said control circuitry;

wherein said control circuitry adjusts brightness of said back light source based on said current ambient light level signal; and

wherein, when said back light source is in said automatic calibration mode, said control circuitry automatically calibrates said brightness of said back light source based on a predefined relation between said current ambient light level and said brightness of said back light source in response to a change in said current ambient light level.

12. The device of claim 11, wherein said optical transmitting devices comprise a set of infrared transmitting devices and said optical receiving devices comprise a set of infrared receiving devices, and wherein said optical position detection device further comprises a frame over said display area for mounting said set of infrared transmitting devices and said set of infrared receiving devices.

13. The device of claim 11, wherein said optical touch panel is arranged on an electrical device.

14. The device of claim 13, wherein said plurality of operation modes comprise a low brightness mode, and wherein in said low brightness mode said back light source is set to a first back light source brightness level and said electrical device is correspondingly set to a normal operation configuration in response to said current ambient light level being maintained at a first ambient light brightness level.

15. The device of claim 13, wherein said plurality of operation modes further comprise a power saving mode, wherein in said power saving mode said back light source is switched off and said electrical device is correspondingly set to a sleep operation configuration in response to said current ambient light level being lower than a second ambient light brightness level, and wherein in said power saving mode, and wherein in said power saving mode said back light source is switched on to a second back light source brightness level and said electrical device is correspondingly set to a normal operation configuration in response to said current ambient light level being higher than said second ambient light brightness level.

16. The device of claim 13, wherein said plurality of operation modes further comprise a normal mode, wherein said back light source is fixedly set to a third back light source brightness level.

17. The device of claim 11, wherein said control circuitry comprises a microprocessor and a memory, and wherein said optical touch panel device further comprises an amplifier electrically coupled between said optical receiving devices and said microprocessor for amplifying said current ambient light level signal generated by said optical receiving devices, said amplifier having a gain inversely proportional to said current ambient light level.

18. The device of claim 17, wherein said memory comprises:

a current gain calculation module for obtaining a current gain G under a user-adjusted normal ambient light condition after said optical receiving devices are exposed for a first period of time;

a minimum gain calculation module for obtaining a minimum gain Gmin under a maximum ambient light condition after said optical receiving devices are exposed for a second period of time; and

a maximum gain calculation module for obtaining a maximum gain Gmax under a minimum ambient light condition after said optical receiving devices are exposed for a third period of time.

19. The device of claim 18, wherein said automatically calibrated brightness is calculated by:

(P2%×

Gmax−

G)/(P2%×

Gmax−

Gmin)=(P1%×

U−

X)/(P1%×

U−

P2%×

U), where U is brightness set by a user, 130%>

P1%>

105%, and 95%>

P2%>

70%.

20. The device of claim 11, wherein said predefined relation comprises a predefined brightness profile, wherein a first calibration brightness profile and a second calibration brightness profile are defined to envelop said pre-defined brightness profile, wherein said first calibration brightness profile is a product of said predefined brightness profile multiplied by P1%, where 130%>

P1%>

105%; and

wherein said second calibration brightness profile is a product of said predefined brightness profile multiplied by P2%, where 95%>

P2%>

70%.