Liquid crystal panel and liquid crystal display device

• US 5,926,161 A
• Filed: 02/01/1996
• Issued: 07/20/1999
• Est. Priority Date: 02/01/1995
• Status: Expired due to Term

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi, Ltd.
• Inventors: Ohta, Masayuki, Kondo, Katsumi, Furuhashi, Tsutomu, Mano, Hiroyuki, Ikeda, Makiko, Futami, Toshio
• Primary Examiner(s): Zimmerman, Mark K.
• Assistant Examiner(s): Laneau, Ronald
• Application Number:
  US08/595,254
• Time in Patent Office: 1,265 Days
• Field of Search: 345/100, 345/94, 345/95, 345/98
• US Class Current: 345/100
• CPC Class Codes: G09G 2300/0434 Flat panel display in which a field is applied parallel to the display plane
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

A liquid crystal panel and a liquid crystal display device including the panel which has a transparent first substrate, a second substrate arranged so as to oppose the first substrate with a space therebetween and liquid crystals filled in the space between the first substrate and the second substrate and having a twist angle which changes in a plane in parallel with a direction of an electric field. The panel has pixels including pixel electrodes connected to source electrodes and counter electrodes with the pixels being arranged in M rows and N columns, where M and N are integers of at least two. Both of the pixel electrodes and the counter electrodes are provided at the second substrate. The panel also includes drain lines independently provided for respective columns, gate lines independently provided for respective rows, and counter lines connected to the counter electrodes. The counter lines include first counter lines at at least one of odd number columns and odd number rows and second counter lines at at least one of even number columns and even number rows with the first and second counter lines being independent of one another.

Claims

1. A liquid crystal panel comprising:

a transparent first substrate;

a second substrate arranged so as to oppose the first substrate with a space therebetween;

liquid crystals in the space between the first substrate and the second substrate and having a twist angle which changes in a plane in parallel with a direction of an electric field;

pixels including thin film transistors (TFT), each TFT having a gate electrode, a drain electrode and a source electrode, the pixels further including pixel electrodes connected to the source electrodes, counter electrodes, the pixels being arranged in M rows and N columns, where M and N are integers of at least two, both of the pixel electrodes and the counter electrodes being provided at the second substrate;

drain lines independently provided for respective columns and connected to the drain electrodes of the pixels belonging to the respective columns;

gate lines independently provided for respective rows and connected to the gate electrodes of the pixels belonging to the respective rows; and

counter lines connected to the counter electrodes;

wherein the counter lines include first counter lines at at least one of odd number columns and odd number rows being connected to the counter electrodes of the pixels belonging to at least one of the odd number columns and the odd number rows and second counter lines at at least one of even number columns and even number rows being connected to the counter electrodes of the pixels belonging to at least one of the even number columns and the even number rows, the first and second counter lines being independent of one another.

2. A liquid crystal panel according to claim 1, wherein the first counter lines are provided at the odd number columns and are connected to the counter electrodes of the pixels belonging to the odd number columns, and the second counter lines are provided at the even number columns and are connected to the counter electrodes of the pixels belonging to the even number columns.

3. A liquid crystal display device comprising:

a liquid crystal panel according to claim 2;

counter electrode drive means for forming counter electrode voltages and applying the counter electrode voltages on the counter lines;

gate drive means for successively selecting one of the gate lines and applying a select voltage on the selected gate line and a nonselect voltage on the unselected gate lines thereby applying the select voltage on the respective gate electrodes at every one frame period; and

drain drive means for forming a positive drain voltage having a voltage level higher than the counter electrode voltages and a negative drain voltage having a voltage level lower than the counter electrode voltages with respect to one display data for alternately applying the positive drain voltage and the negative drain voltage on the drain lines at the every one frame period.

4. A liquid crystal display device according to claim 3, wherein the counter electrode drive means enables forming a high level counter electrode voltage and a low level counter electrode voltage having a voltage level lower than a voltage level of the high level counter electrode voltage as the counter electrode voltages, the counter electrode drive means applying alternately the high level counter electrode voltage and the low level counter electrode voltage of first phases on the first counter lines and applying alternately the low level counter electrode voltage and the high level counter electrode voltage of second phases which are reverse to the first phases on the second counter lines, and the drain drive means applying the negative drain voltage on the drain lines corresponding to the first and second counter lines on which the high level counter electrode voltage is applied and applying the positive drain voltage on the drain lines corresponding to the first and second counter lines on which the low level counter electrode voltage is applied.

5. A liquid crystal display device according to claim 4, wherein a difference between the positive drain voltage and the negative drain voltage is less than 5 V.

6. A liquid crystal display device according to claim 4, wherein when the entire liquid crystal panel is viewed with respect to a thickness direction of the liquid crystal panel a first region between the pixel electrodes and the counter electrodes is transparent and a second region other than the first region is opaque.

7. A liquid crystal display device according to claim 6, wherein at least one of the pixel electrodes and the counter electrodes is transparent.

8. A liquid crystal display device according to claim 7, wherein both of the pixel electrodes and counter electrodes are transparent.

9. A liquid crystal panel according to claim 1, wherein when the entire liquid crystal panel is viewed with respect to a thickness direction of the liquid crystal panel a first region between the pixel electrodes and the counter electrodes is transparent and a second region other than the first region is opaque.

10. A liquid crystal panel according to claim 9, wherein at least one of the pixel electrodes and the counter electrodes is transparent.

11. A liquid crystal panel according to claim 10, wherein both of the pixel electrodes and counter electrodes are transparent.

12. A liquid crystal panel according to claim 1, wherein the first counter lines are provided at the odd number rows and are connected to the counter electrodes of the pixels belonging to the odd number rows, and the second counter lines are provided at the even number rows and are connected to the counter electrodes of the pixels belonging to the even number rows.

13. A liquid crystal display device comprising:

a liquid crystal panel according to claim 12;

counter electrode drive means for forming counter electrode voltages and applying the counter electrode voltages on the counter lines;

gate drive means for successively selecting one of the gate lines and applying a select voltage on the selected gate line and a nonselect voltage on the unselected gate lines thereby applying the select voltage on the respective gate electrodes at every one frame period; and

drain drive means for forming a positive drain voltage having a voltage level higher than the counter electrode voltages and a negative drain voltage having a voltage level lower than the counter electrode voltages with respect to one display data for alternately applying the positive drain voltage and the negative drain voltage at every other row.

14. A liquid crystal display device according to claim 13, wherein the counter electrode drive means enables forming a high level counter electrode voltage and a low level counter electrode voltage having a voltage level lower than a voltage level of the high level counter electrode voltage as the counter electrode voltages, the counter electrode drive means applying alternately the high level counter electrode voltage and the low level counter electrode voltage of first phases on the odd number row counter electrodes and applying the low level counter electrode voltage and the high level counter electrode voltage of second phases reverse to the first phases on the second counter lines, and wherein the drain drive means applies the negative drain voltage on the drain lines when the gate line corresponding to the first and second counter lines on which the high level counter electrode voltage is applied is selected and applies a positive drain voltage on the drain lines when the gate line corresponding to the first and second counter lines on which the low level counter electrode voltage is applied is selected.

15. A liquid crystal display device according to claim 14, wherein a difference between the positive drain voltage and the negative drain voltage is less than 5 V.

16. A liquid crystal display device according to claim 14, wherein when the entire liquid crystal panel is viewed with respect to a thickness direction of the liquid crystal panel a first region between the pixel electrodes and the counter electrodes is transparent and a second region other than the first region is opaque.

17. A liquid crystal display device according to claim 16, wherein at least one of the pixel electrodes and the counter electrodes are transparent.

18. A liquid crystal display device according to claim 17, wherein both of the pixel electrodes and counter electrodes are transparent.

19. A liquid crystal panel according to claim 1, wherein the first counter lines are connected to the counter electrodes of the pixels belonging to the odd number rows and the odd number columns and to the even number rows and the even number columns, and the second counter lines are connected to the counter electrodes of the pixels belonging to the even number rows and the odd number columns and to the odd number rows and the even number columns.

20. A liquid crystal display device comprising:

a liquid crystal panel according to claim 19;

counter electrode drive means for forming a counter electrode voltage and applying the counter electrode voltage on the counter lines;

gate drive means for successively selecting one of the gate lines of the liquid crystal panel and applying a select voltage on the selected gate line and a nonselect voltage on the unselected gate lines, thereby applying the select voltage on the respective gate electrodes at every one frame period; and

drain drive means for forming a positive drain voltage having a voltage level higher than the counter electrode voltages and a negative drain voltage having a voltage level lower than the counter electrode voltages with respect to one display data for alternately applying the positive drain voltage and the negative drain voltage on the drain lines at every other row.

21. A liquid crystal display device according to claim 20, wherein the counter electrode drive means enables forming a high level counter electrode voltage and a low level counter electrode voltage having a voltage level lower than a voltage level of the high level counter electrode voltage as the counter electrode voltages, the counter electrode drive means applying alternately the high level counter electrode voltage and the low level counter electrode voltage of first phases on the first counter lines and applying the low level counter voltage and the high level counter electrode voltage of second phases which are reverse to the first phases on the second counter lines, and the drain drive means applying the negative drain voltage on the drain lines corresponding to the pixels when with respect to the respective pixels belonging to the selected row the high level counter electrode voltage is applied on the counter electrodes corresponding to the pixels and applying the positive drain voltage on the drain lines corresponding to the pixels when the low level counter electrode voltage is applied on the counter electrodes corresponding to the pixels.

22. A liquid crystal display device according to claim 21, wherein a difference between the positive drain voltage and the negative drain voltage is less than 5 V.

23. A liquid crystal display device according to claim 21, wherein when the entire liquid crystal panel is viewed with respect to a thickness direction of the liquid crystal panel a first region between the pixel electrodes and the counter electrodes is transparent and a second region other than the first region is opaque.

24. A liquid crystal display device according to claim 23, wherein at least one of the pixel electrodes and the counter electrodes is transparent.

25. A liquid crystal display device according to claim 24, wherein both of the pixel electrodes and counter electrodes are transparent.

26. A liquid crystal display device according to claim 1, wherein said pixel electrodes and said counter electrodes provided at the second substrate enable generation of the electric field having a component predominantly in parallel with one of the first and second substrates.