Image display device, image display method and display drive device, together with electronic equipment using the same

• US 6,011,533 A
• Filed: 07/21/1997
• Issued: 01/04/2000
• Est. Priority Date: 08/30/1995
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Aoki, Toru
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): Marc-Coleman, Marthe Y.
• Application Number:
  US08/836,524
• Time in Patent Office: 897 Days
• Field of Search: 345/98, 345/99, 345/100, 345/92, 345/96, 345/213
• US Class Current: 345/92
• 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 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

This invention relates to an image display device that samples stabilized pixel data within a sampling period, to display an image with no ghosting. A liquid crystal panel 100 consists of pixels disposed at pixel positions formed at intersections between a plurality of data signal lines 112 and a plurality of scan signal lines 110 arranged in matrix form. A scan signal line selection circuit 102 supplies a scan signal to the scan signal lines 110 in sequence. The phase-expansion circuit 32 samples an image signal having time-series data corresponding to each of said pixel positions in accordance with a first sampling period, and outputs in parallel a plurality of phase-expaned signals that have been converted to a time length of data that is longer than the first sampling period. A plurality of sampling circuits 106 connected to corresponding data signal lines 112 each receive one of the plurality of phase-expaned signals, samples the pixel data in the phase-expaned signal according to a second sampling period, and supplies a data signal to the data signal lines 112. A sampling signal generation circuit 104 generates a sampling signal having the second sampling period that is shorter than a period of time corresponding to the time length of data in the phase-expaned signals, and supplies it to the sampling circuits 106.

Claims

1. An image display device comprising:

an image display portion formed of pixels disposed at pixel positions formed by crossing a plurality of data signal lines and a plurality of scan signal lines arranged in a matrix form;

a scan signal line selection circuit that supplies a scan signal to said scan signal lines in sequence;

a phase-expansion circuit that samples an image signal which has time-series data corresponding to each of said pixel positions in accordance with a first sampling period, converting said image signal into a plurality of phase-expanded signals including a plurality of pixel data, respectively, and outputting said phase-expanded signals in parallel, and a time-length of each of said pixel data being longer than said first sampling period;

a plurality of sampling circuits connected to said data signal lines, respectively, each of said plurality of sampling circuits receiving one of said phase-expanded signals, samples said plurality of pixel data in a received phase-expanded signal in accordance with sampling signals having second sampling periods, and supplies sampled pixel data as a data signal to one of said data signal lines; and

a sampling signal generator that generates said sampling signals which have said second sampling periods that are each shorter than a period corresponding to a time length of each of said pixel data in said phase-expanded signals, and that supplies said sampling signals to said plurality of sampling circuits.

2. The image display device as defined in claim 1,

wherein said phase-expansion circuit outputs said phase-expanded signals in parallel with different head positions of said pixel data in said phase-expanded signals on the basis of a reference clock signal;

wherein said sampling signal generator supplies said sampling signals to said plurality of sampling circuits with different head positions of said second sampling periods of said sampling signals; and

wherein said pixels connected to each of said scan signal lines are driven by a point-at-a-time scanning.

3. The image display device as defined in claim 2,

wherein said sampling signal generator comprises:

a shift register having a plurality of stages in which an output signal from each stage is output at a timing that partially overlaps a phase of a preceding-stage output signal; and

a plurality of AND circuits, each of which is connected to one of said plurality of sampling circuits, receives two of said output signals of mutually overlapping signal phase from said shift register, ANDs said two output signals, and outputs the AND as said sampling signal to said connected sampling circuits.

4. The image display device as defined in claim 1,

wherein said phase-expansion circuit outputs said phase-expanded signals in parallel with head positions of said pixel data thereof aligned;

wherein said sampling signal generator supplies said sampling signals to said plurality of sampling circuits connected to said data signal lines, the number of which is equal to the total number of phase-expanded signal lines while said sampling signals start sampling simultaneously; and

wherein said pixels connected to each of said scan signal lines are simultaneously driven by a predetermined number which is equal to the total number of said phase-expanded signal lines.

5. The image display device as defined in claim 4,

wherein said sampling signal generator comprises a shift register which outputs a signal later than a preceding signal by one cycle of a reference clock signal;

wherein during an mth simultaneous drive {(where;

1≦

m≦

(total number of pixels on one scan signal line)/(total number of said phase-expanded signal lines)}, the (3m-2)th output of said shift register during one horizontal scanning period is input to said plurality of sampling circuits.

6. The image display device as defined in claim 1,

wherein said image display portion is a liquid crystal panel in which a liquid crystal is arranged between a pair of substrates;

wherein said plurality of sampling circuits comprise a plurality of thin-film transistors formed on one of said substrates; and

wherein said sampling signals from said sampling signal generator are supplied to gates of said thin-film transistors.

7. The image display device as defined in claim 1,

wherein said image display portion is a liquid crystal panel in which a liquid crystal is arranged between a pair of substrates;

wherein said image display portion is driven by applying a voltage that is a difference between voltages applied to one side of said pixels through said data signal lines and another side thereof, into said liquid crystal at said pixel positions to invert a polarity of an electric field applied to said liquid crystal;

wherein said image display device further comprises polarity inversion circuit in a stage before said phase-expansion circuit that receives said image signals, generates a first-polarity image signal which drives said pixels at a first polarity with respect to a polarity inversion reference potential and a second-polarity image signal which drives said pixels at a second polarity that is the opposite of said first polarity, and outputs one of said first- and second-polarity image signals to said phase-expansion circuit; and

wherein said phase-expansion circuit performs phase-expansion for said first- and second-polarity image signals and outputs first- and second-polarity phase-expanded signals.

8. The image display device as defined in claim 7,

wherein said polarity inversion circuit comprises a first polarity inversion circuit that outputs one of said first- and second-polarity image signals and a second polarity inversion circuit that outputs the other of said first- and second-polarity image signals.

9. The image display device as defined in claim 1,

wherein said image display portion is a liquid crystal panel in which a liquid crystal is arranged between a pair of substrates;

wherein said image display portion is driven by applying a voltage that is a difference between voltages applied to one side of each of said pixels through said data signal lines and on another side thereof, into said liquid crystal at said pixel positions to invert a polarity of an electric field applied to said liquid crystal; and

wherein said image display device further comprises a plurality of polarity inversion circuits in a stage after said phase-expansion circuit, that receives one of said phase-expanded signals, generates a first-polarity phase-expanded signal which drives said pixels at a first polarity with respect to a polarity inversion reference potential and a second-polarity phase-expanded signal which drives said pixels at a second polarity that is the opposite of said first polarity, and outputs one of said first- and second-polarity phase-expanded signals to said plurality of sampling circuits.

10. The image display device as defined in claim 9,

wherein each of said plurality of polarity inversion circuits comprise a first polarity inversion circuit that outputs one of said first- and second-polarity phase-expanded signals and a second polarity inversion circuit that outputs the other of said first- and second-polarity phase-expanded signals.

11. The image display device as defined in claim 9, further comprising:

switching circuits that switch between said first- and second-polarity phase-expanded signals for supply to said plurality of sampling circuits; and

a changing control device that controls the change of a phase-expansion sequence performed by said phase-expansion circuit, and also controls the change of destinations of said first- and second polarity phase-expanded signals in said switching elements, in accordance with said phase-expansion sequence.

12. The image display device as defined in claim 1, further comprising:

switching elements that switch between said plurality of phase-expanded signals for supply to said plurality of sampling circuits; and

a changing control device that controls the change of a phase-expansion sequence performed by said phase-expansion circuit and also controls the change of destinations of said plurality of phase-expanded signals in said switching elements, in accordance with said phase-expansion sequence.

13. The image display device as defined in claim 7, further comprising:

switching elements that switch between said first- and second-polarity phase-expanded signals for supply to said plurality of sampling circuits; and

a changing control device that controls the change of a phase-expansion sequence performed by said phase-expansion circuit, and also controls the change of destinations of said first- and second-polarity phase-expanded signals in said switching elements, in accordance with said phase-expansion sequence.

14. Electronic equipment having an image display device as defined in claim 1.

15. A display drive device that drives an image display portion formed of pixels disposed at pixel positions formed by crossing a plurality of data signal lines and a plurality of scan signal lines arranged in a matrix form, said display drive device comprising:

a scan signal line selection circuit that supplies a scan signal to said scan signal lines in sequence;

a phase-expansion circuit that samples an image signal which has a time-series data corresponding to each of said pixel positions in accordance with a first sampling period, converts said image signal into a plurality of phase-expanded signals including a plurality of pixel data, respectively, and outputs said phase-expanded signals in parallel, and a time length of each of said pixel data being longer than said first sampling period;

a plurality of sampling circuits connected to said data signal lines, respectively, each of said plurality of sampling circuits receives one of said phase-expanded signals, samples said plurality of pixel data in a received phase-expanded signal in accordance with sampling signals having second sampling periods, and supplies sampled pixel data as a data signal to one of said data signal lines; and

a sampling signal generator that generates said sampling signals which have said second sampling periods that are each shorter than a period corresponding to a time-length of each of said pixel data in said phase-expanded signals, and that supplies said sampling signals to said plurality of sampling circuits.

16. An image display driving pixels at pixels positions formed by crossing a plurality of data signal lines and a plurality of scan signal lines arranged in a matrix form, said image display method comprising:

a step of sampling an image signal which has a time-series data corresponding to each of said pixel positions in accordance with a first sampling period, converting said image signal into a plurality of phase-expanded signals having a plurality of pixel data, respectively, and outputting said phase-expanded signals in parallel, and a time length of each of said pixel data being longer than said first sampling period;

a step of sampling said plurality of pixel data in each of said phase-expanded signals in accordance with second sampling periods that are each shorter than a period corresponding to a time length of each of said pixel data in said phase-expanded signals; and

a step of sequentially selecting said scan signal lines and supplying a plurality of pixel data sampled from said phase-expanded signals to a plurality of said pixels on a selected scan signal line through said data signal lines.

17. An image display device comprising:

an image display portion formed of pixels disposed at pixel positions formed by crossing a plurality of data signal lines and a plurality of scan signal lines arranged in a matrix form;

scan signal line selection means for supplying a scan signal to said scan signal lines in sequence;

phase-expansion means for sampling an image signal which has time-series data corresponding to each of said pixel positions in accordance with a first sampling period, converting said image signal into a plurality of phase-expanded signals including a plurality of pixel data, respectively, and outputting said phase-expanded signals in parallel, and a time-length of each of said pixel data being longer than said first sampling period;

a plurality of sampling means connected to said data signal lines, respectively, each of said plurality of sampling means receiving one of said phase-expanded signals, sampling said plurality of pixel data in a received phase-expanded signal in accordance with sampling signals having second sampling periods, and supplying sampled pixel data as a data signal to one of said data signal lines; and

sampling signal generation means for generating said sampling signals which have said second sampling periods that are each shorter than a period corresponding to a time length of each of said pixel data in said phase-expanded signals, and for supplying said sampling signals to said plurality of sampling means.

18. A display drive device for driving an image display portion formed of pixels disposed at pixel positions formed by crossing a plurality of data signal lines and a plurality of scan signal lines arranged in a matrix form, said display drive device comprising:

a scan signal line selection means for supplying a scan signal to said scan signal lines in sequence;

phase-expansion means for sampling an image signal which has a time-series data corresponding to each of said pixel positions in accordance with a first sampling period, converting said image signal into a plurality of phase-expanded signals including a plurality of pixel data, respectively, and outputting said phase-expanded signals in parallel, and a time length of each of said pixel data being longer than said first sampling period;

a plurality of sampling means connected to said data signal lines, respectively, each of said plurality of sampling means receiving one of said phase-expanded signals, sampling said plurality of pixel data in a received phase-expanded signal in accordance with sampling signals having second sampling periods, and supplying sampled pixel data as a data signal to one of said data signal lines; and

sampling signal generation means for generating said sampling signals which have said second sampling periods that are each shorter than a period corresponding to a time-length of each of said pixel data in said phase-expanded signals, and for supplying said sampling signals to said plurality of sampling means.