Driving method and drive control circuit of liquid crystal display device, and liquid crystal display device including the same

• US 7,342,561 B2
• Filed: 06/24/2003
• Issued: 03/11/2008
• Est. Priority Date: 06/27/2002
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Furukoshi, Yasutake, Kobayashi, Tetsuya, Katagawa, Koichi, Nishido, Masanori, Hiraki, Katsuyoshi
• Primary Examiner(s): Shankar; Vijay
• Application Number:
  US10/603,067
• Publication Number:
  US 20040041778A1
• Time in Patent Office: 1,722 Days
• Field of Search: 345 87-104, 345204-215
• US Class Current: 345/87
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 3/3677 suitable for active matrices only
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

A drive control circuit supplies a gate voltage so that display quality is not degraded even in a case where a vertical scanning frequency or a horizontal scanning frequency is changed. The circuit includes a timing controller for detecting a change of a horizontal scanning frequency, a gate voltage generating circuit for generating two kinds of gate-on voltages Va and Vb (Va<Vb), and a switch for outputting one of the gate-on voltages Va and Vb from the gate voltage generating circuit in accordance with an output of the timing controller. The timing controller includes a counter for counting the number of clocks for one horizontal period, and a comparator for comparing a count result with a threshold value. When the horizontal scanning frequency is in a normal state, the low gate-on voltage Va is outputted, and when the horizontal scanning frequency exceeds a predetermined threshold value, that is, the count value falls below a threshold value, the high gate-on voltage Vb is outputted.

Claims

1. A driving method of a liquid crystal display device, comprising:

a detection step of detecting a change of a vertical scanning frequency or a horizontal scanning frequency; and

an output step of outputting, according to the change of the vertical scanning frequency or the horizontal scanning frequency detected at the detection step, a gate-on voltage corresponding to a magnitude of the change,

wherein at the detection step, it is judged whether the vertical scanning frequency or the horizontal scanning frequency exceeds a predetermined threshold value,

wherein at the output step,

when it is judged at the detection step that the vertical scanning frequency or the horizontal scanning frequency exceeds the predetermined threshold value, a high gate-on voltage as compared with a case where the vertical scanning frequency or the horizontal scanning frequency is the predetermined threshold value or lower is outputted.

2. A driving method of a liquid crystal display device according to claim 1, wherein at the detection step,

it is judged whether the vertical scanning frequency or the horizontal scanning frequency exceeds a first threshold value,

and when it is judged that the vertical scanning frequency or the horizontal scanning frequency exceeds the first threshold value, it is judged whether the vertical scanning frequency or the horizontal scanning frequency falls below a second threshold value.

3. A driving method of a liquid crystal display device according to claim 1, wherein at the output step, the gate-on voltage is generated in accordance with the change of the vertical scanning frequency or the horizontal scanning frequency.

4. A driving method of a liquid crystal display device according to claim 1, further comprising a step of, when the change of the vertical scanning frequency or the horizontal scanning frequency is detected at the detection step, outputting a common voltage corresponding to the detected change.

5. A drive control circuit of a liquid crystal display device, comprising:

a detection circuit for detecting a change of a vertical scanning frequency or a horizontal scanning frequency; and

an output circuit for outputting, according to the change of the vertical scanning frequency or the horizontal scanning frequency detected by the detection circuit, a gate-on voltage corresponding to a magnitude of the change,

wherein the detection circuit comprises;

a first judgment circuit for judging whether the vertical scanning frequency or the horizontal scanning frequency exceeds a first threshold value; and

a second judgment circuit for judging, when it is judged that the vertical scanning frequency or the horizontal scanning frequency exceeds the first threshold value, whether the vertical scanning frequency or the horizontal scanning frequency falls below a second threshold value.

6. A drive control circuit of a liquid crystal display device according to claim 5, wherein the detection circuit includes a circuit for comparing the vertical scanning frequency or the horizontal scanning frequency with a predetermined threshold value.

7. A drive control circuit of a liquid crystal display device according to claim 5, wherein

the output circuit outputs a first gate-on voltage when the first judgment circuit judges that the vertical scanning frequency or the horizontal scanning frequency exceeds the first threshold value,

and outputs a second gate-on voltage lower than the first gate-on voltage when the second judgment circuit judges that the vertical scanning frequency or the horizontal scanning frequency falls below the second threshold value.

8. A drive control circuit of a liquid crystal display device according to claim 5, wherein

the detection circuit outputs a pulse width modulation signal corresponding to the vertical scanning frequency or the horizontal scanning frequency, and

the output circuit generates the gate-on voltage corresponding to a pulse width of the pulse width modulation signal.

9. A drive control circuit of a liquid crystal display device according to claim 5, further comprising a circuit for, when the change of the vertical scanning frequency or the horizontal scanning frequency is detected by the detection circuit, outputting a common voltage corresponding to the detected change.

10. A driving method of a liquid crystal display device, comprising:

a detection step of detecting a change of a vertical scanning frequency or a horizontal scanning frequency; and

an output step of outputting, according to the change of the vertical scanning frequency or the horizontal scanning frequency detected at the detection step, a common voltage corresponding to a magnitude of the change,

wherein at the detection step,

it is judged whether the vertical scanning frequency or the horizontal scanning frequency exceeds a first threshold value,

and when it is judged that the vertical scanning frequency or the horizontal scanning frequency exceeds the first threshold value, it is judged whether the vertical scanning frequency or the horizontal scanning frequency falls below a second threshold value.

11. A driving method of a liquid crystal display device according to claim 10, wherein at the detection step, it is judged whether the vertical scanning frequency or the horizontal scanning frequency exceeds a predetermined threshold value.

12. A drive control circuit of a liquid crystal display device, comprising:

a detection circuit for detecting a change of a vertical scanning frequency or a horizontal scanning frequency; and

an output circuit for outputting, according to the change of the vertical scanning frequency or the horizontal scanning frequency detected by the detection circuit, a common voltage corresponding to a magnitude of the change,

wherein the detection circuit comprises;

a first judgment circuit for judging whether the vertical scanning frequency or the horizontal scanning frequency exceeds a first threshold value; and

a second judgment circuit for judging, when it is judged that the vertical scanning frequency or the horizontal scanning frequency exceeds the first threshold value, whether the vertical scanning frequency or the horizontal scanning frequency falls below a second threshold value.

13. A drive control circuit of a liquid crystal display device according to claim 12, wherein the detection circuit includes a circuit for comparing the vertical scanning frequency or the horizontal scanning frequency with a predetermined threshold value.

14. A drive control circuit of a liquid crystal display device according to claim 12, wherein

the output circuit outputs a first common voltage when the first judgment circuit judges that the vertical scanning frequency or the horizontal scanning frequency exceeds the first threshold value,

and outputs a second common voltage lower than the first common voltage when the second judgment circuit judges that the vertical scanning frequency or the horizontal scanning frequency falls below the second threshold value.

15. A driving method of a liquid crystal display device, comprising:

a detection step of detecting an ambient temperature; and

an output step of outputting, according to a change of the ambient temperature detected at the detection step, a common voltage corresponding to a magnitude of the change,

wherein at the detection step,

it is judged whether the ambient temperature exceeds a first threshold value, and

when it is judged that the ambient temperature exceeds the first threshold value, it is judged whether the ambient temperature falls below a second threshold value.

16. A driving method of a liquid crystal display device according to claim 15, wherein at the detection step, it is judged whether the ambient temperature exceeds a predetermined threshold value.

17. A drive control circuit of a liquid crystal display device, comprising:

a detection circuit for detecting a change of an ambient temperature; and

an output circuit for outputting, according to the change of the ambient temperature is detected by the detection circuit, a common voltage corresponding to a magnitude of the detected change,

wherein the detection circuit comprises;

a first judgment circuit for judging whether the ambient temperature exceeds a first threshold value; and

a second judgment circuit for judging, when it is judged that the ambient temperature exceeds the first threshold value, whether the ambient temperature falls below a second threshold value.

18. A drive control circuit of a liquid crystal display device according to claim 17, wherein the detection circuit includes a circuit for comparing the ambient temperature with a predetermined threshold value.

19. A drive control circuit of a liquid crystal display device according to claim 17, wherein

the output circuit outputs a first common voltage when the first judgment circuit judges that the ambient temperature exceeds the first threshold value,

and outputs a second common voltage lower than the first common voltage when the second judgment circuit judges that the ambient temperature falls below the second threshold value.