Liquid crystal display and driving circuit thereof

• US 7,292,211 B2
• Filed: 03/10/2004
• Issued: 11/06/2007
• Est. Priority Date: 11/14/2003
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Shih, Hung-Min, Chao, Zuei-Tien
• Primary Examiner(s): DHARIA, PRABODH M
• Application Number:
  US10/797,219
• Publication Number:
  US 20050104825A1
• Time in Patent Office: 1,336 Days
• Field of Search: 345204-213, 345/98, 345/94, 345/14, 345/102, 345/629, 345/690, 345 87- 90, 345/72, 345/1.1, 345/3.1, 345/76, 345/92, 345/173, 345/167, 345/107, 345/99, 251/129.04, 362/241
• US Class Current: 345/87
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

A driving circuit for a liquid crystal display. The liquid crystal display panel includes a plurality of light emitting elements and display cells. The display cells are respectively connected to a plurality of data electrodes and gate electrodes. A gate driver outputs scan signals to the gate electrodes. A data driver outputs the video signals to the data electrodes according to the image control signal, and a voltage controlling signal corresponding to a brightness adjustment signal. A driving voltage generator outputs a driving voltage to the light emitting elements according to the voltage controlling signal.

Claims

1. A driving circuit for outputting a video signal to control a liquid crystal display panel according to an image control signal provided by a host, the liquid crystal display panel including a plurality of light emitting elements and display cells, the display cells respectively connecting to a plurality of data electrodes and gate electrodes, the driving circuit comprising:

a gate driver outputting scan signals to the gate electrodes;

a data driver outputting the video signals to the data electrodes according to the image control signal, and a voltage controlling signal corresponding to a brightness adjustment signal; and

a driving voltage generator outputting a driving voltage to the light emitting elements according to the voltage controlling signal.

2. The driving circuit as claimed in claim 1, wherein the voltage controlling signal comprises a plurality of square waves having periods of high voltage level and low voltage level.

3. The driving circuit as claimed in claim 1, wherein the data driver adjusts the ratio between the periods of the high voltage level and the low voltage level according to the brightness adjustment signal.

4. The driving circuit as claimed in claim 3, wherein the driving voltage generator comprises:

a switch having a control gate receiving the voltage controlling signal and turned on or off according to the voltage level of the voltage controlling signal;

an inductor coupled between the switch and a power source;

a diode coupled between the switch and the inductor; and

a capacitor coupled to the diode, wherein the connection point of the capacitor and the diode outputs the driving voltage.

5. The driving circuit as claimed in claim 4, wherein the level of the driving voltage is generated according to the ratio between the periods of the high voltage level and the low voltage level.

6. The driving circuit as claimed in claim 1, wherein the light emitting elements comprise a plurality of LEDs connected in serial, parallel, or a combination of both, and a first terminal coupled to the driving voltage generator and a second terminal coupled to the data driver.

7. The driving circuit as claimed in claim 6, wherein the data driver adjusts the ratio between the periods of the high voltage level and the low voltage level of the voltage controlling signal according to the voltage level of the second terminal.

8. The driving circuit as claimed in claim 6, further comprising a load coupled between the second terminal and ground.

9. A driving circuit for outputting a video signal to control a liquid crystal display panel according to an image control signal provided by a host, the liquid crystal display panel including a plurality of light emitting elements and display cells, the display cells respectively connecting to a plurality of data electrodes and gate electrodes, the driving circuit comprising:

a gate driver outputting scan signals to the gate electrodes, and a voltage controlling signal corresponding to a brightness adjustment signal;

a data driver outputting the video signals to the data electrodes according to the image control signal; and

a driving voltage generator outputting a driving voltage to the light emitting elements according to the voltage controlling signal.

10. The driving circuit as claimed in claim 9, wherein the voltage controlling signal comprises a plurality of square waves having periods of a high voltage level and a low voltage level.

11. The driving circuit as claimed in claim 9, wherein the gate driver adjusts the ratio between the periods of the high voltage level and the low voltage level according to the brightness adjustment signal.

12. The driving circuit as claimed in claim 11, wherein the driving voltage generator comprises:

a switch having a control gate receiving the voltage controlling signal and turned on or off according to voltage level of the voltage controlling signal;

an inductor coupled between the switch and a power source;

a diode coupled between the switch and the inductor; and

a capacitor coupled to the diode, wherein the connection point of the capacitor and the diode outputs the driving voltage.

13. The driving circuit as claimed in claim 12, wherein the level of the driving voltage is generated according to the ratio between the periods of the high voltage level and the low voltage level.

14. The driving circuit as claimed in claim 9, wherein the light emitting elements comprise a plurality of LEDs connected in serial, parallel, or a combination of both, and a first terminal coupled to the driving voltage generator and a second terminal coupled to the data driver.

15. The driving circuit as claimed in claim 14, wherein the data driver adjusts the ratio between the periods of the high voltage level and the low voltage level of the voltage controlling signal according to the voltage level of the second terminal.

16. The driving circuit as claimed in claim 14, further comprising a load coupled between the second terminal and ground.

17. A liquid crystal display for displaying images according to an image control signal provided by a host, comprising:

a liquid crystal display panel comprising a plurality of display cells respectively connected to a plurality of data electrodes and gate electrodes;

a panel driver outputting scan signals to the gate electrodes, the video signals to the data electrodes according to the image control signal, and a voltage controlling signal corresponding to a brightness adjustment signal;

a driving voltage generator outputting a driving voltage according to the voltage controlling signal; and

a plurality of light emitting elements connected in serial and coupled to the driving voltage generator generating brightness corresponding to the driving voltage output by the driving voltage generator.

18. The liquid crystal display as claimed in claim 17, wherein the voltage controlling signal comprises a plurality of square waves having periods of a high voltage level and a low voltage level.

19. The liquid crystal display as claimed in claim 17, wherein the panel driver adjusts the ratio between the periods of the high voltage level and the low voltage level according to the brightness adjustment signal.

20. The liquid crystal display as claimed in claim 17, wherein the driving voltage generator comprises:

a switch having a control gate for receiving the voltage controlling signal and turned on or off according to voltage level of the voltage controlling signal;

an inductor coupled between the switch and a power source;

a diode coupled between the switch and the inductor; and

a capacitor coupled to the diode, wherein the connection point of the capacitor and the diode outputs the driving voltage.

21. The liquid crystal display as claimed in claim 20, wherein the level

of the driving voltage is generated according to the ratio between the periods of the high voltage level and the low voltage level.

22. The liquid crystal display as claimed in claim 17, wherein the light emitting elements comprise a plurality of LEDs connected in serial, parallel, or a combination of both, and a first terminal coupled to the driving voltage generator and a second terminal coupled to the panel driver.

23. The liquid crystal display as claimed in claim 22, wherein the panel driver adjusts the ratio between the periods of the high voltage level and the low voltage level of the voltage controlling signal according to the voltage level of the second terminal.

24. The liquid crystal display as claimed in claim 23, further comprising a load coupled between the second terminal and ground.