Liquid crystal display device and display method of the same

• US 6,115,020 A
• Filed: 10/04/1996
• Issued: 09/05/2000
• Est. Priority Date: 03/29/1996
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Fujitsu Limited
• Inventors: Nakamura, Masanori, Taguchi, Yoshihisa, Tanaka, Katsunori, Isogai, Hiroyuki, Miyamoto, Hirofumi, Kai, Tsutomu, Kishida, Katsuhiko, Onodera, Toshiya
• Primary Examiner(s): Saras, Steven J.
• Assistant Examiner(s): AWAD, AMR A
• Application Number:
  US08/726,021
• Time in Patent Office: 1,432 Days
• Field of Search: 345/130, 345/131, 345/132, 345/87, 345/98, 345/99, 345/100, 348/793
• US Class Current: 345/99
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2340/0414 Vertical resolution change
• CPC Class Codes: G09G 2340/0421 Horizontal resolution change
• CPC Class Codes: G09G 2340/0471 Vertical positioning
• CPC Class Codes: G09G 2340/0478 Horizontal positioning
• CPC Class Codes: G09G 2340/0485 Centering horizontally or vertically
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3677 suitable for active matrices only
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: G09G 5/005 Adapting incoming signals to the display format of the display terminal
• CPC Class Codes: G09G 5/006 Details of the interface to the display terminal specific for a display terminal using a CRT G09G1/167; using a flat panel G09G3/2096; circuits for interfacing with colour displays G09G5/04

Abstract

A display device includes a display panel having display pixels arranged in matrix formation. A first driver circuit sequentially supplies image data to vertical lines of the display panel in synchronism with a first clock signal. A second driver circuit sequentially drives horizontal lines in synchronism with a second clock signal. A control circuit controls a drive timing at which the second driver circuit sequentially drives the horizontal lines so that identical image data equal to one horizontal line is supplied, from the first driver circuit in synchronism with the first clock signal, to two consecutive horizontal lines every N horizontal lines (N is an integer) in accordance with an enlargement ratio at which an image is enlarged in a vertical direction and is displayed on the display panel.

Claims

1. A display device comprising:

a display panel having display pixels arranged in matrix formation;

a first driver circuit which sequentially supplies image data to vertical lines of the display panel in synchronism with a first clock signal;

a second driver circuit which sequentially drives horizontal lines in synchronism with a second clock signal; and

a control circuit which controls a drive timing at which said second driver circuit sequentially drives the horizontal lines so that identical image data is supplied from said first driver circuit in synchronism with the first clock signal to two consecutive horizontal lines every N horizontal lines (N is an integer) in accordance with a non-integer enlargement ratio at which an image is enlarged in a vertical direction and is displayed on the display panel;

wherein said control circuit controls said second driver circuit so that a predetermined amount of image data equal to two consecutive horizontal lines is supplied to each of the horizontal lines so that a first half of the predetermined amount of image data is supplied to one horizontal line and then a second half thereof is supplied to said one horizontal line; and

said control circuit further controls said second driver circuit so that said second driver circuit drives two consecutive horizontal lines at each cycle of the second clock signal, and prevents the second half of the predetermined amount of image data from being supplied to said one horizontal line when said identical image data is supplied to one of said two consecutive horizontal lines.

2. The display device as claimed in claim 1, wherein said control circuit controls said second driver circuit so that each of the horizontal lines is supplied from said first driver circuit with said predetermined amount of image data equal to two consecutive horizontal lines within a period equal to twice the cycle of said second clock signal.

3. The display device as claimed in claim 1, wherein said control circuit generates an enable signal including a pulse which prevents the first driver circuit from supplying said identical image data to said one of the two consecutive horizontal lines.

4. The display device as claimed in claim 1, wherein said control circuit controls said second driver circuit so that the image data is sequentially supplied to the horizontal lines during a constant period less than the cycle of said second clock signal.

5. The display device as claimed in claim 1, wherein the number N can be externally selected based on the enlargement ratio so that the enlargement ratio can be changed.

6. The display device as claimed in claim 1, wherein said control circuit controls, on the basis of the enlargement ratio, a start horizontal line from which the image data is sequentially supplied to the horizontal lines.

7. The display device as claimed in claim 1, further comprising a second control circuit which controls a drive timing at which said first driver circuit sequentially supplies the image data to the horizontal lines so that identical pixel data contained in the image data is successively supplied to one horizontal line being driven every M pixels (M is an integer) in accordance with a second enlargement ratio at which an image is enlarged in a horizontal direction and is displayed on said display panel.

8. The display device as claimed in claim 7, wherein the number N is equal to the number M and the enlargement ratio relating to the vertical direction is equal to said second enlargement ratio relating to the horizontal direction.

9. The display device as claimed in claim 7, wherein said second control circuit controls said first driver circuit so that the image data is sequentially supplied to the horizontal lines in synchronism with a timing based on a number of pixels of said display panel and said second enlargement ratio relating to the horizontal direction.

10. The display device as claimed in claim 1, wherein said display panel is a liquid crystal display panel.

11. A method of controlling a display device comprising a display having display pixels arranged in matrix formation, said method comprising the steps of:

(a) sequentially supplying image data to vertical lines of the display panel in synchronism with a first clock signal;

(b) sequentially driving horizontal lines in synchronism with a second clock signal;

(c) controlling a drive timing at which the horizontal lines are sequentially driven by the step (b) so that identical image data is supplied in synchronism with the first clock signal to two consecutive horizontal lines every N horizontal lines (N is an integer) in accordance with a non-integer enlargement ratio at which an image is enlarged in a vertical direction and is displayed on the display panel;

(d) controlling the step (b) so that a predetermined amount of image data equal to two consecutive horizontal lines is supplied to each of the horizontal lines so that a first half of the predetermined amount of image data is supplied to one horizontal line and then a second half thereof is supplied to said one horizontal line; and

(e) controlling the step (b) so that two consecutive horizontal lines are driven at each cycle of the second clock signal, and the second half of the predetermined amount of image data is prevented from being supplied to said one horizontal line when said identical image data is supplied to one of said two consecutive horizontal lines.

12. The method as claimed in claim 11, further comprising the step of controlling the step (b) so that each of the horizontal lines is supplied with said predetermined amount of image data equal to two consecutive horizontal lines within a period equal to twice the cycle of said second clock signal.

13. The method as claimed in claim 11, further comprising the step of controlling the step (b) so that the image data is sequentially supplied to the horizontal lines during a constant period less than the cycle of said second clock signal.

14. The method as claimed in claim 11, further comprising the step of controlling the step (a) so that identical pixel data contained in the image data is successively supplied to one horizontal line being driven every M pixels (M is an integer) in accordance with another enlargement ratio at which an image is enlarged in a horizontal direction and is displayed on the display panel.

15. A display device comprising:

a display panel having display pixels arrange in matrix formation;

a first drive circuit which sequentially supplies image data to vertical lines of the display panel in synchronism with a first clock signal;

a second driver circuit which sequentially drives horizontal lines in synchronism with a second clock signal; and

a control circuit which controls a drive timing at which said second driver circuit sequentially drives the horizontal lines so that identical image data is supplied from said first driver circuit in synchronism with the first clock signal, to two consecutive horizontal lines every N horizontal line (N is an integer) in accordance with a non-integer enlargement ratio at which an image is enlarged in a vertical direction and is displayed on said display panel;

wherein said control circuit serially drives the two consecutive horizontal lines so that each of the two consecutive horizontal lines is driven for a period shorter than one cycle of the second clock signal.

16. The display device as claimed in claim 15, wherein:

the second driver circuit comprises a first circuit part and a second circuit part;

the first circuit part sequentially drives odd-numbered horizontal lines, and the second circuit part sequentially drives even-numbered horizontal lines;

the first and second circuit parts alternately drive the horizontal lines one by one; and

the control circuit controls the first and second circuit parts in one cycle of the second clock signal so that one of the two consecutive lines is driven by the first circuit part and the other one of the two consecutive lines is driven by the second circuit part.

17. The display device as claimed in claim 15, further comprising a second control circuit which controls a drive timing at which said first driver circuit sequentially supplies the image data to the horizontal lines so that identical pixel data contained in the image data is successively supplied to one horizontal line being driven every M pixels (M is an integer) in accordance with a second enlargement ratio at which an image is enlarged in a horizontal direction and is displayed on said display panel.

18. The display device as claimed in claim 17, wherein the number N is equal to the number M and the enlargement ratio relating to the vertical direction is equal to said second enlargement ratio relating to the horizontal direction.

19. The display device as claimed in claim 15, wherein said display panel is a liquid crystal display panel.

20. A method of controlling a display device comprising a display panel having display pixels arranged in matrix formation, said method comprising the steps of:

(a) sequentially supplying image data to vertical lines of the display panel in synchronism with a first clock signal;

(b) sequentially driving horizontal lines in synchronism with a second clock signal; and

(c) controlling the step (b) so that identical image data supplied by the step (a) in synchronism with the first clock signal is supplied within one cycle of the second clock signal to two consecutive horizontal lines every N horizontal lines (N is an integer) in accordance with a non-integer enlargement ratio at which an image is enlarged in vertical direction and is displayed on the display panels;

wherein the step (c) serially drives the two consecutive horizontal lines so that each of the two consecutive horizontal lines is driven for a period shorter than one cycle of the second clock signal.

21. The method as claimed in claim 20, wherein:

the step (b) comprises the step (b-1) of alternately driving the horizontal lines one by one via a first circuit part and a second circuit part; and

the step (c) comprises the step of controlling the step (b-1) in one cycle of the second clock signal so that one of the two consecutive lines is driven by the first circuit part and the other one of the two consecutive lines is driven by the second circuit part.

22. The method as claimed in claim 20, further comprising the step of controlling the step (a) so that identical pixel data contained in the image data is successively supplied to one horizontal line being driven every M pixels (M is an integer) in accordance with a second enlargement ratio at which an image is enlarged in a horizontal direction and is displayed on the display panel.

23. A display device comprising:

a display panel having display pixels arranged in matrix formation;

a first circuit which samples an image signal by a first clock signal synchronized with the image signal, and performs a predetermined process for sampled image data, said predetermined process being carried out by a second clock signal depending on a number of the display pixels of said display panel;

said first circuit including an A/D converter which converts the image signal in analog formation into serial digital data, a serial-to-parallel converter which converts the serial digital data into parallel data, a latch circuit which latches the parallel data, and a multiplexer which sequentially selects data contained in the parallel data;

said A/D converter and said serial-to-parallel converter operate in synchronism with the first clock signal, and said multiplexer operates in synchronism with the second clock signal;

a second circuit which produces the first clock signal and the second clock signal; and

said second circuit including a first generator circuit which produces the first clock signal synchronized with the image signal, a second generator circuit which produces the second clock signal based on the number of the display pixels of said display panel, a counter which counts the second clock signal to thereby produce a select signal by which the multiplexer sequentially selects the data contained in the parallel data, and a control circuit which controls the counter on the basis of an enlargement ratio,

whereby an image having a smaller number of dots than the number of pixels of said display panel can be enlarged and displayed.

24. The display device as claimed in claim 23, wherein the control circuit stops the counter counting the second clock signal on the basis of the enlargement ratio.

25. The display device as claimed in claim 23, wherein said second circuit further comprises a circuit which discriminates the enlargement ratio from horizontal and vertical synchronizing signals contained in the image signal, so that the second circuit controls the counter based on the enlargement ratio thus discriminated.

26. The display device as claimed in claim 23, wherein:

said first circuit comprises an A/D converter which converts the image signal in analog formation into digital data, and a frame memory which stores the digital data every predetermined number of bits;

said A/D converter operates in synchronism with the first clock signal;

a write operation of the frame memory is carried out in synchronism with the first clock signal; and

a read operation of the frame memory is carried out in synchronism with the second clock signal.

27. The display device as claimed in claim 26, wherein said second circuit comprises a first generator circuit which generates the first clock signal synchronized with the image signal, a second generator circuit which generates the second clock signal based on the number of the display pixels of said display panel, and an address counter which counts the second clock signal in accordance with the enlargement ratio so that an address used to read the digital data from the frame memory is generated.

28. The display device as claimed in claim 27, wherein the address counter stops counting at a predetermined timing based on the enlargement ratio.

29. The display device as claimed in claim 27, wherein said second circuit further comprises a circuit which discriminates the enlargement ratio from horizontal and vertical synchronizing signals contained in the image signal, so that said second circuit controls the counter based on the enlargement ratio thus discriminated.