System and method for achieving optimal display contrast in a mobile communication device

• US 7,209,150 B2
• Filed: 11/05/2001
• Issued: 04/24/2007
• Est. Priority Date: 11/06/2000
• Status: Expired due to Term

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Research In Motion Limited (Blackberry Limited)
• Inventors: Tran, Phat H., Lowles, Robert J., Reksnis, Marek
• Primary Examiner(s): Hjerpe; Richard
• Assistant Examiner(s): DINH, DUC Q
• Application Number:
  US10/007,831
• Publication Number:
  US 20020054010A1
• Time in Patent Office: 1,996 Days
• Field of Search: 305 87- 89, 305101-102, 305/690, 345/690, 345 87- 89, 345101-102, 345/204
• US Class Current: 345/690
• CPC Class Codes: G06F 3/04897 Special input arrangements or commands for improving display capability
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: H04M 1/22 Illumination; Arrangements for improving the visibility of characters on dials
• CPC Class Codes: H04M 1/72448 with means for adapting the functionality of the device according to specific conditions

Abstract

A system and method for achieving optimal display contrast in a mobile communication device is provided. The system includes a memory device, a processor, a display driver, and a display. A user contrast setting is stored in the memory device, wherein the user contrast setting is selected from a range of user contrast settings. The processor includes an operating system that is configured to retrieve the user contrast setting from the memory device, convert the user contrast setting into a hardware contrast setting, and save the hardware contrast setting to a memory location. The display driver retrieves the hardware contrast setting from the memory location and generates a contrast control voltage as a function of the hardware contrast setting. The display is coupled to the contrast control voltage and has a variable contrast ratio, wherein the variable contrast ratio of the display is controlled by the contrast control voltage.

Claims

1. A mobile device, comprising:

a user contrast setting stored in a memory device, wherein the user contrast setting is selected from a range of user contrast settings;

a processor having an operating system configured to retrieve the user contrast setting from the memory device, convert the user contrast setting into a hardware contrast setting, and save the hardware contrast setting to a memory location;

a display driver that retrieves the hardware contrast setting from the memory location and generates a contrast voltage as a function of the hardware contrast setting; and

a display coupled to the contrast voltage and having a variable contrast ratio, wherein the variable contrast ratio of the display is controlled by the contrast voltage;

wherein the processor limits the user contrast setting to a usable range corresponding to a usable range of the contrast voltages, the usable range of the contrast voltages being narrower than a full range of contrast voltages that the driver is configured to be capable of generating to control the contrast ratio.

2. The mobile device of claim 1, wherein the display is a liquid crystal display.

3. The mobile device of claim 1, wherein the user contrast setting is an integer.

4. The mobile device of claim 1, wherein the hardware contrast setting is an integer.

5. The mobile device of claim 1, wherein the user contrast setting selected from the middle of the range of user contrast settings results in an optimal contrast ratio for the display.

6. The mobile device of claim 1, wherein the highest user contrast setting that may be selected from the range of user contrast settings results in a pre-selected high contrast ratio for the display.

7. The mobile device of claim 1, wherein the lowest user contrast setting that may be selected from the range of user contrast settings results in a pre-selected low contrast ratio for the display.

8. The mobile device of claim 1, wherein the display driver includes the memory location to which the hardware contrast setting is stored.

9. The mobile device of claim 1, further comprising:

a contrast offset stored in the memory device, wherein the contrast offset is used by the operating system to convert the user contrast setting into a hardware contrast setting.

10. The mobile device of claim 9, wherein the contrast offset is an integer.

11. The mobile device of claim 9, wherein the contrast offset is calibrated and stored in the memory device by a mobile device manufacturer.

12. The mobile device of claim 1, further comprising:

a contrast scale stored in the memory device, wherein the contrast scale is used by the operating system to convert the user contrast setting into a hardware contrast setting.

13. The mobile device of claim 12, wherein the contrast scale is an integer.

14. The mobile device of claim 12, wherein the contrast scale is calibrated and stored in the memory device by a mobile device manufacturer.

15. The mobile device of claim 1, further comprising:

an input device coupled to the processor that enables a mobile device user to input the user contrast setting;

wherein the operating system is further configured to receive the user contrast setting from the input device and save the user contrast setting to the memory device.

25. The device of claim 1 wherein the display includes a backlight that adds luminance to the display when activated, and the device further comprises a backlight adjustment stored in the memory device, wherein the backlight adjustment increments or decrements the user contrast setting to compensate for the luminance from the backlight.

16. A method of controlling the contrast ratio of a liquid crystal display (LCD) in a mobile device, comprising the steps of:

storing a user contrast setting in a memory device;

converting the user contrast setting into a hardware contrast setting using a contrast offset and a contrast scale; and

converting the hardware contrast setting into a contrast voltage using a display driver, wherein the contrast voltage controls the contrast ratio of the LCD;

activating a backlight that adds luminance to the display; and

in response to the backlight being activated without using a light sensor to sense the luminance, incrementing or decrementing the user contrast setting to compensate for the luminance from the backlight, the incrementing or decrementing being determined based on a backlight adjustment stored in the memory device.

17. The method of claim 16, comprising the additional step of:

receiving the user contrast setting from a mobile device user.

18. The method of claim 16, comprising the additional step of:

storing the hardware contrast setting in a memory location.

19. The method of claim 16, wherein the user contrast setting is selected from a range of user contrast settings having a middle setting, and comprising the additional step of:

calibrating the contrast offset such that the middle setting in the range of user contrast settings corresponds to an optimal contrast ratio for the LCD.

20. The method of claim 19, wherein the calibration step is performed by a mobile device manufacturer.

21. The method of claim 16, wherein the user contrast setting is selected from a range of user contrast settings, and comprising the additional step of:

calibrating the contrast scale such that the range of user contrast settings falls between a pre-selected low contrast ratio for the LCD and a pre-selected high contrast ratio for the LCD.

22. The method of claim 21, wherein the calibration step is performed by a mobile device manufacturer.

23. The method of claim 16, comprising the additional step of:

calibrating the backlight adjustment value such that the contrast ratio of the LCD when the LCD backlight is on is substantially the same as the contrast ratio of the LCD when the LCD backlight is off.

24. The method of claim 23, wherein the calibration step is performed by a mobile device manufacturer.