Display device having an improved video signal drive circuit

• US 7,193,603 B2
• Filed: 11/03/2004
• Issued: 03/20/2007
• Est. Priority Date: 04/16/2001
• Status: Expired due to Fees

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi, Ltd.
• Inventors: Miyazawa, Toshio, Mamba, Norio
• Primary Examiner(s): Hjerpe; Richard
• Assistant Examiner(s): NGUYEN, KIMNHUNG T
• Application Number:
  US10/979,153
• Publication Number:
  US 20050088432A1
• Time in Patent Office: 867 Days
• Field of Search: 345 87- 89, 345 98-100, 345/205, 345/206
• US Class Current: 345/100
• CPC Class Codes: G09G 2310/0275 Details of drivers for data electrodes, other than drivers for liquid crystal, plasma or OLED displays, not related to handling digital grey scale data or to communication of data to the pixels by means of a current
• CPC Class Codes: G09G 2310/0297 Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A display device includes a plurality of pixels, a plurality of signal lines connected to the plurality of pixels and a drive circuit connected to the plurality of signal lines. The drive circuit includes a distribution port and a decoder, wherein the distribution port distributes supplied data to corresponding circuit portions in the decoder, and the decoder selects gray scale voltages based upon the data from the distribution port. The distribution port includes a first switching stage having two switching elements and a second switching stage having four switching elements and which is electrically connected to the first switching stage. The decoder is disposed between the second switching stage and the plurality of signal lines.

Claims

1. A display device comprising:

a plurality of pixels;

a plurality of signal lines connected to the plurality of pixels; and

a drive circuit connected to the plurality of signal lines, the drive circuit comprising a distribution port and a decoder;

wherein the distribution port distributes supplied data to corresponding circuit portions in the decoder, and the decoder selects gray scale voltages based upon the data from the distribution port, the distribution port including a first switching stage having two switching elements and a second switching stage having four switching elements and which is electrically connected to the first switching stage; and

wherein the decoder is disposed between the second switching stage and the plurality of signal lines.

2. A display device according to claim 1, wherein the first switching stage is supplied with a first clock signal, and the second switching stage is supplied with a second clock signal having a frequency which is one half of a frequency of the first clock signal.

3. A display device according to claim 2, wherein the first clock signal includes a first clock pulse and a second clock pulse which has an opposite phase from a phase of the first clock pulse, and the second clock signal includes a third clock pulse and a fourth clock pulse which has an opposite phase from a phase of the third clock pulse.

4. A display device according to claim 3, wherein the two switching elements of the first switching stage receive serial data, and the four switching elements of the second stage receive output data from the first switching stage.

5. A display device according to claim 3, wherein the distribution port further includes a third switching stage having eight switching elements and which is electrically connected to the second switching stage, a fourth switching stage having sixteen switching elements and which is electrically connected to the third switching stage, and a fifth switching stage having thirty-two switching elements and which is electrically connected to the fourth switching stage.

6. A display device according to claim 5, wherein the decoder is electrically connected to the fifth switching stage.

7. A display device according to claim 5, wherein the third switching stage is supplied with a fifth clock pulse and a sixth clock pulse which has an opposite phase from a phase of the fifth clock pulse, the fourth switching stage is supplied with a seventh clock pulse and an eighth clock pulse which has an opposite phase from a phase of the seventh clock pulse, and the fifth switching stage is supplied with a ninth clock pulse and a tenth clock pulse which has an opposite phase from a phase of the ninth clock pulse.

8. A display device according to claim 6, wherein the ninth clock pulse has a frequency which is one half of a frequency of the seventh clock pulse, the seventh clock pulse has a frequency which is one half of a frequency of the fifth clock pulse, and the fifth clock pulse has a frequency which is one half of a frequency of the third clock pulse.

9. A display device according to claim 8, wherein the tenth clock pulse has a frequency which is one half of a frequency of the eighth clock pulse, the eighth clock pulse has a frequency which is one half of a frequency of the sixth clock pulse, and the sixth clock pulse has a frequency which is one half of a frequency of the fourth clock pulse.

10. A display device according to claim 4, further comprising a data conversion circuit electrically connected to the drive circuit, wherein the data conversion circuit changes an arrangement of externally supplied data, and outputs the rearranged data as the serial data to the distribution port.

11. A display device according to claim 10, wherein the data conversion circuit includes a first conversion switching stage having two switching elements and which outputs the serial data, and a second conversion switching stage having four switching elements and which is electrically connected to the first switching stage.

12. A display device according to claim 11, wherein the first conversion switching stage is supplied with an eleventh clock pulse and a twelfth clock pulse which has an opposite phase from a phase of the eleventh clock pulse, and the second conversion switching stage is supplied with a thirteenth clock pulse and a fourteenth clock pulse which has an opposite phase from a phase of the thirteenth clock pulse.

13. A display device according to claim 12, wherein the first clock pulse and the eleventh clock pulse have a same frequency, and the third clock pulse and the thirteenth clock pulse have a same frequency.

14. A display device comprising:

a plurality of pixels;

a plurality of signal lines connected to the plurality of pixels; and

a drive circuit connected to the plurality of signal lines, the drive circuit comprising a distribution port and a decoder;

wherein the distribution port distributes supplied data to corresponding circuit portions in the decoder, and the decoder selects gray scale voltages based upon the data from the distribution port, the distribution port including a first switching stage having two switching elements and which receives serial data, and a second switching stage having four switching elements and which is electrically connected to the first switching stage;

wherein the two switching elements of the first switching stage receive a first clock pulse and a second clock pulse which has an opposite phase from a phase of the first clock pulse, and the four switching elements of the second switching stage receive a third clock pulse and a fourth clock pulse which has an opposite phase from a phase of the third clock pulse; and

wherein the decoder is disposed between the second switching stage and the plurality of signal lines.

15. A display device according to claim 14, wherein the third clock pulse and the fourth clock pulse have a frequency which is one half of a frequency of the first clock pulse and the second clock pulse.

16. A display device according to claim 14, further comprising:

a data conversion circuit electrically connected to the drive circuit;

wherein the data conversion circuit changes an arrangement of externally supplied data, and outputs the rearranged data to the distribution port;

wherein the data conversion circuit includes a first conversion switching stage having two switching elements and a second conversion switching stage having four switching elements and which is electrically connected to the first switching stage; and

wherein the first conversion switching stage outputs the serial data to the drive circuit.

17. A display device according to claim 15, wherein the first conversion switching stage is supplied with a fifth clock pulse and a sixth clock pulse which has an opposite phase from a phase of the fifth clock pulse, and the second conversion switching stage is supplied with a seventh clock pulse and an eighth clock pulse which has an opposite phase from a phase of the seventh clock pulse.

18. A display device according to claim 17, wherein the third clock pulse and the fourth clock pulse have a frequency which is one half of a frequency of the first clock pulse and the second clock pulse.

19. A display device according to claim 17, wherein the seventh clock pulse and the eighth clock pulse have a frequency which is one half of a frequency of the fifth clock pulse and the sixth clock pulse.

20. A display device according to claim 17, wherein the first clock pulse and the fifth clock pulse have a same frequency, and the third clock pulse and the seventh clock pulse have a same frequency.