Liquid crystal display device

• US 5,552,801 A
• Filed: 09/02/1994
• Issued: 09/03/1996
• Est. Priority Date: 07/28/1989
• Status: Expired due to Term

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi, Ltd.
• Inventors: Takashi, Terumi, Furuhashi, Tsutomu, Mano, Hiroyuki, Futami, Toshio, Nishioka, Kiyokazu
• Primary Examiner(s): Weldon, Ulysses
• Assistant Examiner(s): Luu, Matthew
• Application Number:
  US08/299,671
• Time in Patent Office: 732 Days
• Field of Search: 345/87, 345/88, 345/92, 345/98, 345/100
• US Class Current: 345/100
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/3607 for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: H04N 3/127 using liquid crystals

Abstract

A liquid crystal display device providing a multi tone control function is disclosed, permitting a multi-colored display to be provided by using an analogue display data input, while regulating stepwise the brightness by varying the level of the applied voltage. The liquid crystal display device is composed of serial/parallel converter having a high sampling speed, into which liquid crystal display data are inputted, with function of converting serial image data into parallel image data, and an X axis direction driver having a low sampling speed, into which the liquid crystal display data for one pixel are inputted, with a function of outputting the liquid crystal display data of one line in the horizontal direction, synchronized with a display line signal for a Y axis direction driver. The S/P converter and the X axis direction driver are disposed separately. Further the S/P converter and the X axis direction driver are constructed so as to hold analogue quantities in order to output the liquid crystal display data applied to the liquid crystal driving elements constituting the pixels of a liquid crystal display panel in the form of analogue signals. In this way a multi-colored display of not less than nine colors, using an analogue input, can be effected, and it is possible to display arbitrarily levels of brightness by varying the level of the applied voltage.

Claims

1. A liquid crystal display device for providing signals for application to a liquid crystal display panel having a plurality of display panel rows, to cause a display made up of a plurality of display lines, each display line including a plurality of pixels, each display panel row of said display panel including a plurality of switching elements, each switching element normally assuming a non-selected state and responsive to application thereto of a selecting voltage for assuming a selected state, each switching element in its selected state applying to an associated display area of the display panel a voltage corresponding to data to be displayed in the associated display area and in its non-selected state retaining the associated display area at its most recent corresponding voltage, said liquid crystal display device comprising:

an input buffer storage circuit, including a plurality of first buffer storage elements of a number less than the number of pixels in the display panel row, for receiving serial analog display data corresponding to a plurality of display lines and sequentially storing the received display data in said first buffer storage elements;

an input holding circuit coupled to said input buffer storage circuit, for receiving and simultaneously holding the display data stored in said input buffer storage circuit;

an output buffer storage circuit, including a plurality of second buffer storage elements equal in number to the number of pixels in the display panel row, for sequentially receiving the display data held in said input holding circuit and storing the received display data in said second buffer storage elements; and

an output holding circuit coupled to said output buffer storage circuit, for receiving and simultaneously holding the display data stored in said output buffer storage circuit and for outputting held display data for application to switching elements of the display panel.

2. A liquid crystal display device as claimed in claim 1, wherein said input buffer storage circuit comprises:

a first control circuit responsive to a clock signal for sequentially generating a plurality of first control signals;

a plurality of first capacitors; and

a plurality of first switching elements, each first switching element coupled to an associated one of said first capacitors, each first switching element responsive to a respective one of said plurality of first control signals for applying received serial analog display data to its associated first capacitor for storage.

3. A liquid crystal display device as claimed in claim 2, wherein said input holding circuit comprises:

a plurality of second capacitors; and

a plurality of second switching elements, each second switching element coupled to an affiliated one of said first capacitors and to an affiliated one of said second capacitors, each second switching element responsive to a selected one of said sequentially generated plurality of first control signals, for transferring the stored analog display data from its affiliated first capacitor to its affiliated second capacitor for holding.

4. A liquid crystal display device as claimed in claim 3, wherein said output buffer storage circuit comprises:

a second control circuit responsive to a selected one of said sequentially generated plurality of first control signals, for sequentially generating a plurality of second control signals;

a plurality of third capacitors, each second capacitor associated with a plurality of said third capacitors; and

a plurality of third switching elements, each third switching element responsive to a respective one of said plurality of second control signals for sequentially transferring the held analog display data from one of said second capacitors to one of its associated third capacitors for storage.

5. A liquid crystal display device as claimed in claim 4, wherein said output holding circuit comprises:

a plurality of fourth capacitors; and

a plurality of fourth switching elements, each fourth switching element coupled to an affiliated one of said third capacitors and to an affiliated one of said fourth capacitors, each fourth switching element responsive to a selected one of said sequentially generated plurality of second control signals for transferring the stored analog display data from its affiliated third capacitor to its affiliated fourth capacitor for holding and outputting of the held display data for application to switching elements of said display panel.

6. A liquid crystal display device as claimed in claim 1, wherein each display panel row includes a preselected number of display areas, and said output buffer storage circuit includes a circuit for storing display data for one complete display line.

7. A liquid crystal display device as claimed in claim 1, wherein each display panel row includes a preselected number of display areas, and said output holding circuit includes a circuit for holding display data for one complete display line.

8. A liquid crystal display device as claimed in claim 1, wherein said input buffer storage circuit comprises:

a first control circuit responsive to a clock signal for sequentially generating a plurality of first control signals;

a plurality m of first capacitors, wherein m is a number less than the number of pixels in the display panel row; and

a plurality m of first switching elements, each first switching element coupled to an associated one of said first capacitors, each first switching element responsive to a respective one of said plurality of first control signals for applying received serial analog display data to its associated first capacitor for storage.

9. A liquid crystal display device as claimed in claim 8, wherein said input holding circuit comprises:

a plurality m of second capacitors; and

a plurality m of second switching elements, each second switching element coupled to an affiliated one of said first capacitors and to an affiliated one of said second capacitors, each second switching element responsive to a selected one of said sequentially generated plurality of first control signals, for transferring the stored analog display data from its affiliated first capacitor to its affiliated second capacitor for holding.

10. A liquid crystal display device as claimed in claim 9, wherein said output buffer storage circuit comprises:

a second control circuit responsive to a selected one of said sequentially generated plurality of first control signals, for sequentially generating a plurality of second control signals;

a plurality n of third capacitors, wherein n is a number equal to the number of pixels in the display panel row; and

a plurality n of third switching elements, each third switching element responsive to a selected one of said plurality of second control signals for sequentially transferring the held analog display data from one of said second capacitors to its affiliated third capacitor for storage.

11. A liquid crystal display device as claimed in claim 10, wherein said output holding circuit comprises:

a plurality n of fourth capacitors; and

a plurality n of fourth switching elements, each fourth switching element coupled to an affiliated one of said third capacitors and to an affiliated one of said fourth capacitors, each fourth switching element responsive to a selected one of said sequentially generated plurality of second control signals for transferring the stored analog display date from its affiliated third capacitor to its affiliated fourth capacitor for holding and outputting of the held display data for application to switching elements of said display panel.

12. A liquid crystal display device for providing signals for application to a liquid crystal display panel having a plurality of display panel rows, to cause a display made up of a plurality of display line, each display panel row of said display panel including a plurality of switching elements, each switching element normally assuming a non-selected state and responsive to application thereto of a selecting voltage for assuming a selected state, each switching element in its selected state applying to an associated display area of the display panel a voltage corresponding to data to be displayed in the associated display area and in its non-selected state retaining the associated display area at its most recent corresponding voltage, said liquid crystal display device comprising:

a input buffer storage circuit, including a plurality m of first buffer elements, for receiving serial analog display data corresponding to a plurality of display lines and sequentially storing the received display data in said first buffer storage elements;

an input holding circuit coupled to said input buffer storage circuit, for receiving and simultaneously holding the plurality of display data stored in said input buffer storage circuit;

an output buffer storage circuit, including a plurality n of second buffer storage elements, where n is greater than m, for sequentially receiving said display data held in said input holding circuit and storing the received display data in the second buffer storage elements; and

an output holding circuit coupled to said output buffer storage circuit, for receiving and simultaneously holding the display data stored in said output buffer storage circuit and for outputting held display data for application to switching elements of the display panel.

13. A liquid crystal display device as claimed in claim 12, wherein said input buffer storage circuit comprises:

a first control circuit responsive to a clock signal for sequentially generating a plurality of first control signals;

a plurality m of first capacitors, wherein m is a number less than the number of pixels in the display panel row; and

a plurality m of first switching elements, each first switching element coupled to an associated one of said first capacitors, each first switching element responsive to a respective one of said plurality of first control signals for applying received serial analog display data to its associated first capacitor for storage.

14. A liquid crystal display device as claimed in claim 13, wherein said input holding circuit comprises:

a plurality m of second capacitors; and

a plurality m of second switching elements, each second switching element coupled to an affiliated one of said first capacitors and to an affiliated one of said second capacitors, each second switching element responsive to a selected one of said sequentially generated plurality of first control signals, for transferring the stored analog display data from its affiliated first capacitor to its affiliated second capacitor for holding.

15. A liquid crystal display device as claimed in claim 14, wherein said output buffer storage circuit comprises:

a second control circuit responsive to a selected one of said sequentially generated plurality of first control signals, for sequentially generating a plurality of second control signals;

a plurality n of third capacitors, wherein n is a number equal to the number of pixels in the display panel row; and

a plurality n of third switching elements, each third switching element responsive to a selected one of said plurality of second control signals for sequentially transferring the held analog display data from one of said second capacitors to its affiliated third capacitor for storage.

16. A liquid crystal display device as claimed in claim 15, wherein said output holding circuit comprises:

a plurality n of fourth capacitors; and

a plurality n of fourth switching elements, each fourth switching element coupled to an affiliated one of said third capacitors and to an affiliated one of said fourth capacitors, each fourth switching element responsive to a selected one of said sequentially generated plurality of second control signals for transferring the stored analog display date from its affiliated third capacitor to its affiliated fourth capacitor for holding and outputting of the held display data for application to switching elements of said display panel.