Method for compensating for the attenuation of a liquid crystal display having an LED backlight and display that exhibits an attenuation compensating function

• US 20090224678A1
• Filed: 08/28/2008
• Published: 09/10/2009
• Est. Priority Date: 03/07/2008
• Status: Abandoned Application

• Current Assignee: Dynascan Technology Corporation (Dynascan Technology)
• Original Assignee: Dynascan Technology Corporation (Dynascan Technology)
• Inventors: Wang, Tsun-I
• Application Number:
  US12/230,343
• Publication Number:
  US 20090224678A1
• Time in Patent Office: Days
• US Class Current: 315/158
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• 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 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

Disclosed are a method for compensating for the attenuation of a LCD having an LED backlight and a display that exhibits an attenuation compensating function. After assembling of the entire set of the display, a LCD module mounted in front of the backlight is set in a predetermined state and plural sets of LEDs are lighted one set at a time under predetermined conditions. The resultant data are recorded to obtain information regarding the initial luminous intensity and chromaticity of the respective sets of LEDs. The respective sets of LEDs are tested at a predetermined time point. If the detected value deviates from the initial value beyond a predetermined deviation, the electric output will change automatically for compensating for the attenuation, whereby the luminous intensity and chromaticity of the display are ensured to be as good as brand new.

Claims

1. A method for compensating for the attenuation of a liquid crystal display having an LED backlight, where said display comprises a liquid crystal display module and said LED backlight has plural sets of LED, and where said display is provided with at least one optical sensor, a power supplying device for actuating said plural sets of LED with a variable electric output, a processing device for receiving a value detected by said optical sensor and controlling the electric output of said power supplying device, and a memory device that pre-stores the respective reference values for said plural sets of LED which are detected by said optical sensor when the respective sets of LED are lighted one set at a time at at least one given power level and when said liquid crystal display module is in a predetermined state, said method comprising the steps of:

a) at a predetermined time point, setting said liquid crystal display module to be in said predetermined state and cutting off the power supply to said plural sets of LED;

b) lighting at least one set of said plural sets of LED at the at least one given power level stored in said memory device;

c) comparing the value for said set of LED as detected by said optical sensor with the corresponding reference value that is pre-stored in said memory device; and

d) varying the electric output of the power supplying device to said set of LED by the operation of said processing device if said detected value deviates from the pre-stored reference value beyond a predetermined deviation.

2. The attenuation compensating method according to claim 1, further comprising a looping step e) of lighting and detecting said plural sets of LED one set at a time until all of said plural sets of LED are detected and compared with the corresponding reference values pre-stored in the memory device.

3. The attenuation compensating method according to claim 1, wherein the step c) comprises a synchronous-phase detecting sub-step c1) and a comparing sub-step c2).

4. The attenuation compensating method according to claim 1, further comprising, prior to the step a), a synchronous-phase detecting step f) for the pre-stored reference values.

5. The attenuation compensating method according to claim 1, wherein said predetermined state in the step a) is a state where said liquid crystal display module is fully closed.

6. The attenuation compensating method according to claim 1, wherein said predetermined time point is every time when said display is turned on.

7. The attenuation compensating method according to claim 1, wherein said predetermined time point is a time point at which said display is consecutively operated for a predetermined period of time.

8. A liquid crystal display having an LED backlight, comprising:

a liquid crystal display module;

an LED backlight having plural sets of LED;

an optical sensor;

a power supplying device for actuating said plural sets of LED with a variable electric output;

a memory device that pre-stores the respective reference values for said plural sets of LED which are detected by said optical sensor when the respective sets of LED are lighted one set at a time at at least one given power level and when said liquid crystal display module is in a predetermined state; and

a processing device for receiving a value for one set of said plural sets of LED as detected by said optical sensor when said set of LED is lighted at the at least one given power level pre-stored in said memory device and comparing the detected value for said set of LED with the corresponding reference value that is pre-stored in said memory device and varying the electric output of the power supplying device to said set of LED if said detected value deviates from the pre-stored reference value beyond a predetermined deviation.

9. The display according to claim 8, wherein said optical sensor is a phototransistor.

10. The display according to claim 8, wherein said optical sensor is a photodiode.

11. The display according to claim 8, wherein said optical sensor is a color-photometry sensor.

12. The display according to claim 8, wherein said optical sensor is a solar cell.

13. The display according to claim 8, wherein said plural sets of LED that are adapted for illuminating on the liquid crystal display panel in a direct manner.

14. The display according to claim 8 further comprising a voltage amplifier for amplifying the value detected by the optical sensor and an A/D converter for converting the electric signals output from said voltage amplifier.

15. The display according to claim 8, wherein said power supplying device comprises a pulse width modulation generator.

16. The display according to claim 8, wherein said power supplying device comprises a programmable power source.