BACKLIGHT ADJUSTMENT SYSTEM

• US 20090289580A1
• Filed: 05/21/2008
• Published: 11/26/2009
• Est. Priority Date: 05/21/2008
• Status: Active Grant

• Current Assignee: Manufacturing Resources International, Inc.
• Original Assignee: Manufacturing Resources International, Inc.
• Inventors: Williams, David, Dunn, William, Schuch, John
• Granted Patent: US 8,125,163 B2
• Time in Patent Office: Days
• US Class Current: 315/307
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: H05B 45/12 using optical feedback
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/18 using temperature feedback
• 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 preferred embodiment relates to controlling the amount of backlight in an electronic display to account for the temperature in the backlight cavity. Another embodiment relates to a system for controlling the amount of backlight based on both the temperature in the backlight cavity and the amount of ambient light. The embodiments are especially useful in electronic displays which are subjected to cold or warm temperatures and displays which are placed in very bright environments. Exemplary embodiments allow the display to remain visible, while avoiding possible damage due to high levels of heat or cold.

Claims

1. A system for controlling the backlighting of an electronic display with a backlight cavity, the system comprising:

a backlighting assembly within the backlight cavity of the electronic display;

a power source operatively connected to said backlighting assembly;

a temperature sensing device within the backlight cavity;

a software driver operatively connected to said temperature sensing device and controlling said power source; and

wherein the software driver increases or decreases the amount of power sent to the backlight assembly based on data from said temperature sensing device.

2. The system of claim 1, further comprising a power measurement device operatively connected between said power source and said backlighting assembly and providing power data to said software driver.

3. The system of claim 2, wherein the software driver comprises an eeprom.

4. The system of claim 1, wherein the backlight assembly comprises:

a mounting element;

a reflective element covering one surface of the mounting element; and

one or more illuminating devices fixedly attached to the mounting element on the surface containing the reflective element.

5. The system of claim 4, wherein said mounting device comprises a printed circuit board.

6. The system of claim 4, wherein said one or more illuminating devices comprise any one of the following:

LED'"'"'s, fluorescent lights, organic light emitting diodes (OLED), field emitting display (FED), cathode ray tube (CRT), light emitting polymer (LEP), and organic electro-luminescence (OEL),

7. The system of claim 1 wherein said electronic display is a liquid crystal display.

8. A system for controlling the backlighting of an electronic display with a backlight cavity and a display surface, the system comprising:

a backlighting assembly within the backlight cavity of the electronic display;

a power source operatively connected to said backlighting assembly;

a temperature sensing device within the backlight cavity;

a first light sensing device adjacent to the display surface;

a second light sending device within said backlight cavity; and

a software driver operatively connected to

said temperature sensing device;

said first and second light sensing devices; and

controlling said power source; and

wherein the software driver increases or decreases the amount of power sent to the backlight assembly based on data from said temperature sensing device and said first and second light sensing devices.

9. The system of claim 8 further comprising a power measurement device operatively connected between said power source and said backlighting assembly and providing power data to said software driver.

10. The system of claim 9 wherein said software driver comprises an eeprom.

11. The system of claim 8, wherein the backlight assembly comprises:

a mounting element;

a reflective element covering one surface of the mounting element; and

one or more illuminating devices fixedly attached to the mounting element on the surface containing the reflective element.

12. The system of claim 11, wherein said mounting device comprises a printed circuit board.

13. The system of claim 11, wherein said one or more illuminating devices comprise any one of the following:

LED'"'"'s, fluorescent lights, organic light emitting diodes (OLED), field emitting display (FED), cathode ray tube (CRT), light emitting polymer (LEP), and organic electro-luminescence (OEL),

14. The system of claim 8 wherein said electronic display is a liquid crystal display.

15. A method for controlling the amount of backlighting in an electronic display device, the steps comprising

providing an electronic display comprising

a display housing;

a viewing surface on the front surface of the display housing;

a backlight cavity within the display housing;

a backlight assembly within said backlight cavity; and

a power source connected to said backlight assembly;

sending power from said power source to said backlight assembly;

setting an operating temperature range for said backlight cavity;

measuring the temperature in the backlight cavity;

decreasing the power to the backlight assembly when the temperature in the backlight cavity exceeds the operating temperature range; and

increasing the power to the backlight assembly when the temperature in the backlight cavity falls below the operating temperature range.

16. The method of claim 15 further comprising the steps of:

measuring the amount of light contacting the viewing surface;

measuring the amount of light generated by the backlighting assembly;

defining a light ratio, wherein said light ratio is defined as the ratio of the amount of light contacting the viewing surface to the amount of light generated by the backlight assembly;

setting a preferred light ratio, with a maximum and minimum tolerance;

calculate the current light ratio, based on said light measurements;

increasing the power to the backlight assembly when the current light ratio exceeds the maximum preferred light ratio; and

decreasing the power to the backlight assembly when the current light ratio falls below the minimum preferred light ratio.

17. The method of claim 15 further comprising the steps of:

providing a software driver which is operatively connected to and sends controlling signals to said power source;

measuring the power sent from the power source to the backlight assembly;

comparing the power measurement to the controlling signals from the software driver; and

modifying said controlling signals if said power measurement does not match said controlling signals.