Liquid crystal display apparatus including scanning circuit having bidirectional shift register stages

• US 6,232,939 B1
• Filed: 11/09/1998
• Issued: 05/15/2001
• Est. Priority Date: 11/10/1997
• Status: Expired due to Term

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi, Ltd., Hitachi Device Engineering Co., Ltd. (Japan Display Incorporated)
• Inventors: Sato, Hideo, Matsumoto, Katsumi, Saito, Katsutoshi, Takemoto, Iwao
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Nguyen, Kevin M.
• Application Number:
  US09/188,110
• Time in Patent Office: 918 Days
• Field of Search: 345/93, 345/97, 345/98, 345/100, 345/104, 345/204, 345/211, 345/212, 345/213, 345/197, 345/198
• US Class Current: 345/93
• CPC Class Codes: G09G 2310/0283 Arrangement of drivers for different directions of scanning
• 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 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/3677 suitable for active matrices only
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

A liquid crystal display apparatus has horizontal and vertical scanning circuits for scanning an array of pixels. An image signal applied to an image signal supply circuit in the form of series of pixel signals is transferred to pixels in the array of pixels designated by the horizontal and vertical scanning circuits. Each of the horizontal and vertical scanning circuits have a series connection of bidirectional shift register stages and are capable of bidirectional scanning. Each of the bidirectional shift register stages includes a pair of latches connected in tandem and is capable of providing an intermediate output and a shift register stage output. The pair of latches of each of the bidirectional shift register stages except those located at both ends of the series connection have respective intermediate and bidirectional shift register stage outputs contributing to designation of pixels to which pixel signals are to be supplied, while the pair of latches of the shift register stages located at each end of the series connection have their bidirectional shift register stage outputs contributing to such designation of pixels and their intermediate output terminals not contributing to such designation of pixels.

Claims

1. A liquid crystal display apparatus comprising:

an array of pixels;

a horizontal scanning circuit responsive to a horizontal scanning direction setting signal;

a vertical scanning circuit responsive to a vertical scanning direction setting signal;

an image signal supply circuit to which pixel signals are applied externally, said image signal supply circuit being connected with said array of pixels and being driven by said horizontal scanning circuit; and

a vertical scanning control circuit connected with said array of pixels and being driven by said vertical scanning circuit,

said vertical scanning circuit being cooperative with said horizontal scanning circuit to cause transference of said pixel signals from said image signal supply circuit to said array of pixels, wherein

each of said horizontal scanning circuit and vertical scanning circuit includes a series connection of bidirectional shift register stages, each of said bidirectional shift register stages

(a) having a pair of latches connected in tandem, one of said pair of latches having an intermediate output terminal connected to the other latch, said other latch having a bidirectional shift register stage output terminal connected to a next bidirectional shift register stage, and

(b) being operative with a clock signal to shift a first output from the intermediate output terminal of said one latch to said other latch and to shift a second output from the bidirectional shift register stage output terminal of said other latch to the next bidirectional shift register stage,

in said horizontal scanning circuit, the pair of latches of each of said bidirectional shift register stages except those located at both ends of said series connection have respective intermediate and bidirectional shift register stage output terminals electrically connected to said image signal supply circuit, while the pair of latches of the shift register stages located at each end of said series connection have their bidirectional shift register stage output terminals electrically connected to said image signal supply circuit and their intermediate output terminals not connected to said image signal supply circuit, and

in said vertical scanning circuit, the pair of latches of each of said bidirectional shift register stages except those located at both ends of said series connection have respective intermediate and bidirectional shift register stage output terminals electrically connected to said vertical scanning control circuit, while the pair of latches of the shift register stages located at each end of said series connection have their bidirectional shift register stage output terminals electrically connected to said vertical scanning control circuit and their intermediate output terminals not connected to said vertical scanning control circuit.

2. A liquid crystal display apparatus according to claim 1, wherein

said at least one of said horizontal scanning circuit and vertical scanning circuit further includes a reset circuit, and

said series connection of bidirectional shift register stages are connected with said reset circuit, whereby said bidirectional shift register stages are reset by said reset circuit.

3. A liquid crystal display apparatus according to claim 1, wherein the clock signal for said horizontal scanning circuit includes pulses each for determining a time duration during which a pixel signal is allowed to be supplied to an image signal line connected with said array of pixels so that the pixel signal is supplied to a pixel electrode in said pixel array from said image signal supply circuit.

4. A liquid crystal display apparatus according to claim 1, wherein the clock signal for said vertical scanning circuit includes pulses for determining time durations during which a control signal is allowed to be supplied to a scanning line connected with said array of pixels so that a pixel signal is supplied to a pixel electrode in said pixel array from said image signal supply circuit.

5. A liquid crystal display apparatus according to claim 1, wherein each of said horizontal scanning circuit and vertical scanning circuit has a structure such that a shift operation of each of said shift register stages is responsive to a duty ratio of the clock signal therefor.

6. A liquid crystal projector comprising a liquid crystal display apparatus according to claim 1.

7. A liquid crystal display apparatus comprising, on one and the same substrate, an array of pixels, an image signal supply circuit for supplying pixel signals to said array of pixels and a scanning circuit for outputting a plurality of scanning signals for driving said image signal supply circuit, wherein:

said scanning circuit is capable of scanning in a first direction and a second direction opposite to said first direction; and

said scanning circuit includes a first input/output section serving as an output section of said scanning circuit for scanning in said first direction and serving as an input section of said scanning circuit for scanning in said second direction, a second input/output section serving as an output section of said scanning circuit for scanning in said second direction and serving as an input section of said scanning circuit for scanning in said first direction, and a reset circuit for bringing said first input/output section into an off-state for scanning in said first direction and for bringing said second input/output section into an off-state for scanning in said second direction.

10. A liquid crystal display projector comprising a liquid crystal display apparatus according to claim 7.

8. A liquid crystal display apparatus comprising, on one and the same substrate, an array of pixels, an image signal supply circuit for supplying pixel signals for driving said array of pixels, a vertical scanning control circuit, a horizontal scanning circuit for outputting a horizontal scanning signal for driving said image signal supply circuit and a vertical scanning circuit for outputting a vertical scanning signal for driving said vertical scanning control circuit, wherein:

each of said vertical and horizontal scanning circuits is capable of scanning in a first direction and a second direction opposite to said first direction and includes a plurality of bidirectional shift register stages connected in tandem, each of said bidirectional shift register stages having an intermediate output terminal and a register stage output terminal; and

a first bidirectional shift register stage in said horizontal scanning circuit as viewed in a horizontal direction has its intermediate output terminal not connected with said image signal supply circuit, while a first bidirectional shift register stage in said vertical scanning circuit as viewed in a vertical direction has its intermediate output terminal not connected with said vertical scanning control circuit.

11. A liquid crystal display projector comprising a liquid crystal display apparatus according to claim 8.

9. A liquid crystal display apparatus comprising, on one and the same substrate, an array of pixels, an image signal supply circuit for supplying pixel signals for driving said array of pixels, a vertical scanning control circuit, a horizontal scanning circuit for outputting a horizontal scanning signal for driving said image signal supply circuit and a vertical scanning circuit for outputting a vertical scanning signal for driving said vertical scanning control circuit, wherein:

each of said vertical and horizontal scanning circuits is capable of scanning in a first direction and a second direction opposite to said first direction; and

said vertical and horizontal scanning circuits have structures responsive to duty ratios of said first and second clock signals, respectively to vary time points of start of supply of pixel signals to adjacent pixels when said horizontal and vertical scanning circuits drive said image signal supply circuit and said vertical scanning control circuit so that the pixel signals are supplied to the pixels.

12. A liquid crystal display projector comprising a liquid crystal display apparatus according to claim 9.

13. A liquid crystal display apparatus comprising:

an array of pixels;

a horizontal scanning circuit responsive to a horizontal scanning direction setting signal;

a vertical scanning circuit responsive to a vertical scanning direction setting signal;

an image signal supply circuit which receives pixel signals from an external source, the image signal supply circuit being connected to the array of pixels and being driven by the horizontal scanning circuit; and

a vertical scanning control circuit connected to the array of pixels and being driven by the vertical scanning circuit;

wherein the vertical scanning circuit operates in cooperation with the horizontal scanning circuit to cause the pixel signals to be transferred from the image signal supply circuit to the array of pixels;

wherein each of the horizontal scanning circuit and the vertical scanning circuit includes a series connection of bidirectional shift register stages;

wherein each of the bidirectional shift register stages includes

a first latch,

a second latch,

an intermediate output terminal,

a first input/output terminal, and

a second input/output terminal,

the first latch being connected to the second latch through the intermediate output terminal,

the first latch being connected through the first input/output terminal to a first one of two bidirectional shift register stages adjacent to a bidirectional shift register stage under consideration in the series connection of bidirectional shift register stages, and

the second latch being connected through the second input/output terminal to a second one of the two bidirectional shift register stages adjacent to the bidirectional shift register stage under consideration in the series connection of bidirectional shift register stages;

wherein each of the bidirectional shift register stages

is operative in response to a clock signal, for scanning in a first direction from a first end of the series connection to a second end of the series connection, to shift an output from the first latch through the intermediate output terminal to the second latch and to shift an output from the second latch through the second input/output terminal to the second one of the two bidirectional shift register stages, and

is operative in response to the clock signal, for scanning in a second direction, opposite to the first direction, from the second end of the series connection to the first end of the series connection to shift an output from the second latch through the intermediate output terminal to the first latch and to shift an output from the first latch through the first input/output terminal to the first one of the two bidirectional shift register stages;

wherein in the horizontal scanning circuit,

the first input/output terminal, the intermediate output terminal, and the second input/output terminal of each of the bidirectional shift register stages except ones of the bidirectional shift register stages located at the first end of the series connection and the second end of the series connection are electrically connected to the image signal supply circuit,

the first input/output terminal and the intermediate output terminal of the bidirectional shift register stage located at the first end of the series connection are not electrically connected to the image signal supply circuit, while the second input/output terminal of the bidirectional shift register stage located at the first end of the series connection is electrically connected to the image signal supply circuit, and

the intermediate output terminal and the second input/output terminal of the bidirectional shift register stage located at the second end of the series connection are not electrically connected to the image signal supply circuit, while the first input/output terminal of the bidirectional shift register stage located at the second end of the series connection is electrically connected to the image signal supply circuit; and

wherein in the vertical scanning circuit,

the first input/output terminal, the intermediate output terminal, and the second input/output terminal of each of the bidirectional shift register stages except ones of the bidirectional shift register stages located at the first end of the series connection and the second end of the series connection are electrically connected to the vertical scanning control circuit,

the first input/output terminal and the intermediate output terminal of the bidirectional shift register stage located at the first end of the series connection are not electrically connected to the vertical scanning control circuit, while the second input/output terminal of the bidirectional shift register stage located at the first end of the series connection is electrically connected to the vertical scanning control circuit, and

the intermediate output terminal and the second input/output terminal of the bidirectional shift register stage located at the second end of the series connection are not electrically connected to the vertical scanning control circuit, while the first input/output terminal of the bidirectional shift register stage located at the second end of the series connection is electrically connected to the vertical scanning control circuit.

14. A liquid crystal display apparatus according to claim 13, wherein each of the horizontal scanning circuit and vertical scanning circuit includes a respective reset circuit;

and

wherein the bidirectional shift register stages in each of the horizontal scanning circuit and the vertical scanning are connected to the respective reset circuit, thereby enabling the bidirectional shift register stages in each of the horizontal scanning circuit and the vertical scanning circuit to be reset by the respective reset circuit.

15. A liquid crystal display apparatus according to claim 13, wherein the liquid crystal display apparatus further comprises a plurality of image signal lines connected between the image signal supply circuit and the array of pixels;

and

wherein the clock signal for the bidirectional shift register stages in the horizontal scanning circuit includes pulses each having a width which determines a time duration during which the image signal supply circuit applies a pixel signal to one of the image signal lines during transfer of the pixels signals from the image signal supply circuit to the array of pixels.

16. A liquid crystal display apparatus according to claim 13, wherein the liquid crystal display apparatus further comprises a plurality of scanning signal lines connected between the vertical scanning control circuit and the array of pixels;

and

wherein the clock signal for the bidirectional shift register stages in the vertical scanning circuit includes pulses each having a width which determines a time duration during which the vertical scanning control circuit applies a scanning signal to one of the scanning signal lines during transfer of the pixels signals from the image signal supply circuit to the array of pixels.

17. A liquid crystal display apparatus according to claim 13, wherein each of the bidirectional shift register stages in each of the horizontal scanning circuit and the vertical scanning circuit is responsive to a change in a duty ratio of the clock signal to vary a shift operation of the bidirectional shift register stage.

18. A liquid crystal projector comprising a liquid crystal display apparatus according to claim 13.

19. A liquid crystal display apparatus comprising, on a single substrate:

an array of pixels;

an image signal supply circuit which supplies pixel signals to the array of pixels; and

a plurality of scanning circuits which output respective scanning signals for driving the image signal supply circuit;

wherein each of the scanning circuits is capable of scanning in a first direction and a second direction opposite to the first direction; and

wherein each of the scanning circuits includes

a first input/output section serving as an output section of the scanning circuit for scanning in the first direction and serving as an input section of the scanning circuit for scanning in the second direction,

a second input/output section serving as an output section of the scanning circuit for scanning in the second direction and serving as an input section of the scanning circuit for scanning in the first direction, and

a reset circuit which brings the first input/output section into an off-state for scanning in the first direction and brings the second input/output section into an off-state for scanning in the second direction.

20. A liquid crystal display projector comprising a liquid crystal display apparatus according to claim 19.

21. A liquid crystal display apparatus comprising, on a single substrate:

an array of pixels;

an image signal supply circuit which supplies pixel signals to the array of pixels;

a vertical scanning control circuit connected to the array of pixels;

a horizontal scanning circuit which outputs a horizontal scanning signal for driving the image signal supply circuit; and

a vertical scanning circuit which outputs a vertical scanning signal for driving the vertical scanning control circuit;

wherein each of the horizontal scanning circuit and the vertical scanning circuit is capable of scanning in a first direction based on a first scanning signal, and scanning in a second direction opposite to the first direction based on a second scanning signal;

wherein each of the horizontal scanning circuit and the vertical scanning circuit includes a series connection of bidirectional shift register stages;

wherein each of the bidirectional shift register stages includes

a first latch,

a second latch,

an intermediate output terminal,

a first input/output terminal, and

a second input/output terminal,

the first latch being connected to the second latch through the intermediate output terminal,

the first latch being connected through the first input/output terminal to a first one of two bidirectional shift register stages adjacent to a bidirectional shift register stage under consideration in the series connection of bidirectional shift register stages, and

the second latch being connected through the second input/output terminal to a second one of the two bidirectional shift register stages adjacent to the bidirectional shift register stage under consideration in the series connection of bidirectional shift register stages;

wherein each of the bidirectional shift register stages

is operative in response to a clock signal, for scanning in a first direction from a first end of the series connection to a second end of the series connection, to shift an output from the first latch through the intermediate output terminal to the second latch and to shift an output from the second latch through the second input/output terminal to the second one of the two bidirectional shift register stages, and

is operative in response to the clock signal, for scanning in a second direction, opposite to the first direction, from the second end of the series connection to the first end of the series connection to shift an output from the second latch through the intermediate output terminal to the first latch and to shift an output from the first latch through the first input/output terminal to the first one of the two bidirectional shift register stages;

wherein in the horizontal scanning circuit, the intermediate output terminal of one of the bidirectional shift register stages located at one of the first end of the series connection and the second end of the series connection is not connected to the image signal supply circuit; and

wherein in the vertical scanning circuit, the intermediate output terminal of one of the bidirectional shift register stages located at one of the first end of the series connection and the second end of the series connection is not connected to the vertical scanning control circuit.

22. A liquid crystal display projector comprising a liquid crystal display apparatus according to claim 21.

23. A liquid crystal display apparatus comprising, on a single substrate:

an array of pixels;

an image signal supply circuit which supplies pixel signals to the array of pixels;

a vertical scanning control circuit connected to the array of pixels;

a horizontal scanning circuit which outputs a horizontal scanning signal for driving the image signal supply circuit; and

a vertical scanning circuit which outputs a vertical scanning signal for driving the vertical scanning control circuit;

wherein the vertical scanning circuit operates in cooperation with the horizontal scanning circuit to cause the image signal supply circuit to supply the pixel signals to the array of pixels;

wherein each of the horizontal scanning circuit and the vertical scanning circuit is capable of scanning in a first direction based on a first scanning signal, and scanning in a second direction opposite to the first direction based on a second scanning signal;

wherein each of the horizontal scanning circuit and the vertical scanning circuit includes a series connection of bidirectional shift register stages;

wherein each of the bidirectional shift register stages includes

a first latch,

a second latch,

an intermediate output terminal,

a first input/output terminal, and

a second input/output terminal,

the first latch being connected to the second latch through the intermediate output terminal,

the first latch being connected through the first input/output terminal to a first one of two bidirectional shift register stages adjacent to a bidirectional shift register stage under consideration in the series connection of bidirectional shift register stages, and

the second latch being connected through the second input/output terminal to a second one of the two bidirectional shift register stages adjacent to the bidirectional shift register stage under consideration in the series connection of bidirectional shift register stages;

wherein each of the bidirectional shift register stages

is operative in response to a clock signal, for scanning in a first direction from a first end of the series connection to a second end of the series connection, to shift an output from the first latch through the intermediate output terminal to the second latch and to shift an output from the second latch through the second input/output terminal to the second one of the two bidirectional shift register stages, and

is operative in response to the clock signal, for scanning in a second direction, opposite to the first direction, from the second end of the series connection to the first end of the series connection to shift an output from the second latch through the intermediate output terminal to the first latch and to shift an output from the first latch through the first input/output terminal to the first one of the two bidirectional shift register stages; and

wherein each of the bidirectional shift register stages in each of the horizontal scanning circuit and the vertical scanning circuit is responsive to a change in a duty ratio of the clock signal to vary an interval between times of start of supply of pixel signals to adjacent pixels in the array of pixels.

24. A liquid crystal display projector comprising a liquid crystal display apparatus according to claim 23.