Liquid crystal display apparatus

• US 6,115,017 A
• Filed: 03/19/1997
• Issued: 09/05/2000
• Est. Priority Date: 03/19/1996
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Mikami, Yoshiro, Hirota, Shoichi, Komura, Shinichi, Adachi, Masaya, Masuda, Kazuhito, Sato, Hideo, Tsumura, Makoto, Kuwabara, Kazuhiro, Minemura, Tetsuro, Ohkubo, Tatsuya
• Primary Examiner(s): Shankar, Vijay
• Assistant Examiner(s): PIZIALI, JEFFREY J
• Application Number:
  US08/820,835
• Time in Patent Office: 1,266 Days
• Field of Search: 345/90, 345/98, 345/89, 345/147, 345/99, 345/100, 345/92, 349/48, 349/38, 349/144, 359/59, 340/784
• US Class Current: 345/92
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• CPC Class Codes: G09G 2300/0828 forming a digital to analog [D/A] conversion circuit
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0857 Static memory circuit, e.g. flip-flop
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/10 Special adaptations of display systems for operation with variable images
• CPC Class Codes: G09G 2340/125 wherein one of the images is motion video
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3659 the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes
• CPC Class Codes: G09G 3/3674 Details of drivers for scan electrodes
• CPC Class Codes: G09G 3/3685 Details of drivers for data electrodes

Abstract

An improved liquid crystal display apparatus for low power consumption is provided, within each of the regions surrounded by a plurality of scanning electrodes and a plurality of signal electrodes, with a display data holding circuit connected to the corresponding scanning electrodes and signal electrodes, for fetching and storing a display data from the signal electrode in response to a scanning signal; a switching device connected to the display data holding circuit, its switching operation being controlled by the holding circuit; and a display electrode connected to the switching device.

Claims

1. A liquid crystal display apparatus having a pair of substrates of which at least one substrate is transparent and a liquid crystal layer sandwiched between the substrates, comprising:

a plurality of scanning electrodes formed on one of the substrates; and

a plurality of signal electrodes intersecting in a matrix form with each of said plurality of scanning electrodes;

wherein the display apparatus further comprises, within each of the regions forming pixels surrounded by said plurality of scanning electrodes and said plurality of signal electrodes, each of said pixels being connected with a plurality of signal wiring;

(a) a sampling data holding circuit connected to a corresponding signal electrode, for sampling and storing signal data from the signal electrode in response to a scanning signal;

(b) a gray level selecting circuit connected to said sampling data holding circuit, for selecting gray levels for a pixel in response to a state of the sampling of said sampling data holding circuit; and

(c) a display electrode connected to said gray level selecting circuit, and a plurality of capacitor-transistor circuits being connected to said display electrode.

2. A liquid crystal display apparatus according to claim 1, wherein said sampling data holding circuit comprises:

a plurality of thin film transistors connected to a corresponding scanning electrode at gates thereof and to respective ones of corresponding signal electrodes at one of drains and sources, for sampling signal data from respective ones of said signal electrodes in response to the scanning signal from the scanning electrode; and

a plurality of sampling capacitors connected to respective ones of the other of drains and sources of said plurality of thin film transistors for holding sampled signal data by said plurality of thin film transistors.

3. A liquid crystal display apparatus according to claim 2, wherein said gray level selecting circuit has a plurality of thin film transistors having gates connected to the other of respective drains and sources of said plurality of thin film transistors for sampling and driving said display electrode depending upon holding condition signal data of said sampling capacitor.

4. A liquid crystal display apparatus according to claim 3, wherein one of said substrates is provided with a common electrode connected to said plurality of capacitors of said sampling holding circuit and said plurality of thin film transistors of said gray level selecting circuit.

5. A liquid crystal display apparatus according to claim 3, wherein said thin film transistor is formed with a coplanar structure.

6. A liquid crystal display apparatus according to claim 3, wherein said thin film transistor is an inverse staggered structure.

7. A liquid crystal display apparatus according to claim 3, wherein said thin film transistor is a staggered structure.

8. A liquid crystal display apparatus according to claim 2, wherein a liquid crystal capacity as electrostatic capacity between the scanning electrode, the signal electrode and the common electrode, display electrode of each of the regions formed on one of the substrates, a signal electrode capacity as electrostatic capacity between the signal electrode and a transparent electrode, a wiring capacity as electrostatic capacity at an intersecting portion between the scanning electrode and the signal electrode, and a scanning wiring number satisfy a relationship of

(liquid crystal capacity)<

{(signal electrode capacity)+(wiring intersecting portion capacity)}×

(scanning wiring number).

9. A liquid crystal display apparatus comprising:

a liquid crystal layer including a liquid crystal constructing a plurality of pixels;

a pair of boards facing each other between which said liquid crystal layer is inserted, at least one of said boards being transparent;

a plurality of scanning wires for transmitting scan pulses, distributed on one of said pair of boards;

a plurality of signal wires for transmitting image data, crossing with said plurality of scanning wires in a matrix geometry and distributed on one of said pair of boards;

AC voltage generation means for generating a liquid crystal device voltage for driving said liquid crystal; and

timing signal generation means for generating periodically timing signals in synchronization with said liquid crystal drive voltage generated by said AC voltage generation means;

wherein each of a plurality of display areas enclosed by a plurality of scanning wires and a plurality of signal wires have;

(a) a display electrode placed et one side of said pair of boards;

(b) opposed electrodes placed so as to face said display electrode through said liquid crystal layer, to which said liquid crystal drive voltage is applied by said AC voltage generation means;

(c) a switching device for driving pixels connected to said display electrode;

(d) data hold means for holding image data supplied from a signal wire in response to a scan pulse from a scanning wire and controlling said switching operation of said switching device for driving pixels in response to said held image data; and

(e) initializing means for initializing a voltage applied between said display electrode and said opposed electrode in response to a timing signal supplied by a thin film transistor provided in parallel with said switching device and said timing signal generation means enabling connection of a pixel electrode with a center voltage circuit.

10. A liquid crystal display apparatus comprising:

a liquid crystal layer including a liquid crystal constructing a plurality of pixels;

a pair of boards facing each other between which said liquid crystal layer is inserted, at least one of said boards being transparent;

a plurality of scanning wires for transmitting scan pulses, distributed on one of said pair of boards;

a plurality of signal wires for transmitting image data, crossing with said plurality of scanning wires in a matrix geometry and distributed on one of said pair of boards;

AC voltage generation means for generating a liquid crystal device voltage for driving said liquid crystal; and

timing signal generation means for generating periodically timing signals in synchronization with said liquid crystal drive voltage generated by said AC voltage generation means;

wherein each of a plurality of display areas is enclosed by a plurality of scanning wires and a plurality of signal wires have;

(a) a display electrode placed at one side of said pair of boards;

(b) opposed electrodes placed so as to face said display electrode through said liquid crystal layer, to which said liquid crystal drive voltage is applied by said AC voltage generation means;

(c) a switching device for driving pixels connected to said display electrode;

(d) data holding means for holding image data supplied from a signal wire in response to a scan pulse from a scanning wire and controlling said switching operation of said switching device for driving pixels in response to said held image data; and

(e) resetting means for shorting pixel driving by said switching device in response to a timing signal supplied by said timing signal generation means.

12. A liquid crystal display apparatus of any one of claim 9, 10 and 11, switching device is composed of a TFT device, a signal for switching operation is input to a gate terminal of said TFT device, a drain terminal of said TFT device is connected to a display electrode, and a source terminal is connected to a reference line defining an average voltage of a liquid crystal drive voltage;

and including AC voltage generation means for generating a liquid crystal drive voltage and timing signal generation means for generating a timing signal which is synchronized with a time when said liquid crystal drive voltage generated by said AC voltage generation means reaches an average voltage, generation of said timing signal being interrupted at a time when said voltage applied between a display electrode and an opposed electrode reaches zero so that the AC voltage is set at a center voltage, and when said timing signal is not applied, said liquid crystal drive voltage is applied to said center voltage circuit.

13. A liquid crystal display apparatus according to claim 12, wherein one of said substrates has a common electrode connected to said memory circuit of said display data holding circuit.

14. A liquid crystal display apparatus according to claim 13, wherein said memory circuit is a flip-flop circuit.

11. A liquid crystal display apparatus comprising:

a liquid crystal layer including a liquid crystal constructing a plurality of pixels;

a pair of boards facing each other between which said liquid crystal layer is inserted, at least one of said boards being transparent;

a plurality of scanning wires for transmitting scan pulses, distributed on one of said pair of boards;

a plurality of signal wires for transmitting image data, crossing with said plurality of scanning wires in a matrix geometry and distributed on one of said pair of boards;

AC voltage generation means for generating a liquid crystal device voltage for driving said liquid crystal; and

(a) timing signal generation means for generating periodically timing signals in synchronization with said liquid crystal drive voltage generated by said AC voltage generation means;

wherein each of a plurality of display areas enclosed by a plurality of scanning wires and a plurality of signal wires have;

(a) a display electrode placed at one side of said pair of boards;

(b) opposed electrodes placed so as to face said display electrode through said liquid crystal layer, to which said liquid crystal drive voltage is applied by said AC voltage generation means;

(c) a switching device for driving pixels connected to said display electrode;

(d) data holding means for holding image data supplied from a signal wire in response to a scan pulse from a scanning wire and controlling said switching operation of said switching device for driving pixels in response to said held image data; and

(e) logic means for controlling said pixel driving switching device into an ON state in response to one of a pixel driving image data held in said data holding means and a timing signal from said timing signal generating means.

15. A liquid crystal display apparatus comprising:

a liquid crystal layer disposed between a pair of substrates arranged in opposition to each other, at least one of said substrates being transparent;

a plurality of scanning electrode lines distributed in one of a pair of said substrates;

a plurality of display electrodes arranged within a plurality of display regions respectively surrounded by a plurality of said scanning electrode lines and a plurality of signal electrode lines in said one of said substrates;

opposed electrodes respectively arranged in opposition to said display electrodes across said liquid crystal layer;

first switching devices for static picture and second switching devices for motion picture arranged within a plurality of said display regions and connected to respective display electrodes;

static picture controlling means arranged within said plurality of display regions, for controlling respective ones of a plurality of said first switching devices for static picture on the basis of the signal from said each signal electrode line and said each scanning electrode line and static picture data;

motion picture controlling means arranged within said plurality of display regions, for controlling respective ones of a plurality of said second switching devices for motion picture on the basis of the signal from said each signal electrode line and said each scanning electrode line and motion picture data;

wherein for displaying a static picture, the signal from said signal electrode line and said scanning electrode line and said static picture data is applied to said static picture controlling means in said static picture display region for placing said first switching device for static picture in an ON state and holding static picture data; and

wherein for displaying a motion picture, the signal from said signal electrode line and said scanning electrode line and said motion picture data is applied to said motion picture controlling means in said motion picture display region for placing said second switching device for motion picture in an ON state and holding motion picture data.

19. A liquid crystal display apparatus according to any one of claims 15, 16 and 17, wherein said motion picture control circuit includes a discharging thin film transistor inserted between input electrodes of the static picture switching device with said display electrode being a load and a picture data inputting thin film transistor connected to said motion picture switching device in series, a gate of said discharging thin film transistor is connected to the signal electrode lines together with a gate of the motion picture switching device, a gate of said picture data inputting thin film transistor is connected to the scanning electrode line, and the motion picture is input to a drain thereof.

20. A liquid crystal display apparatus according to any one of claims 15, 16 and 17, wherein said static picture control circuit includes a capacitor disposed between input electrodes of said static picture switching device with said display electrode being a load and a pair of thin film transistors connected in series with said static picture switching device, one of said thin film transistors being connected to said signal electrode line at a gate thereof, and a gate of the other thin film transistor being connected to said scanning electrode line and a drain thereof as input for a static picture data.

21. A liquid crystal display apparatus according to claim 20, wherein said motion picture control circuit includes a discharging thin film transistor inserted between input electrodes of the static picture switching device with said display electrode being a load and a picture data inputting thin film transistor connected to said motion picture switching device in series, a gate of said discharging thin film transistor is connected to the signal electrode lines together with a gate of the motion picture switching device, a gate of said picture data inputting thin film transistor is connected to the scanning electrode line, and the motion picture is input to a drain thereof.

22. A liquid crystal display apparatus according to any one of claims 15, 16 and 17, wherein said motion picture control circuit is connected to said static picture control circuit for discharging the static picture data held by said static picture control circuit upon displaying the motion picture.

23. A liquid crystal display apparatus according to claim 22, wherein said static picture control circuit includes a capacitor disposed between input electrodes of said static picture switching device with said display electrode being a load and a pair of thin film transistors connected in series with said static picture switching device, one of said thin film transistors being connected to said signal electrode line at a gate thereof, and a gate of the other thin film transistor being connected to said scanning electrode line and a drain thereof as input for a static picture data.

24. A liquid crystal display apparatus according to claim 22, wherein said motion picture control circuit includes a discharging thin film transistor inserted between input electrodes of the static picture switching device with said display electrode being a load and a picture data inputting thin film transistor connected to said motion picture switching device in series, a gate of said discharging thin film transistor is connected to the signal electrode lines together with a gate of the motion picture switching device, a gate of said picture data inputting thin film transistor is connected to the scanning electrode line, and the motion picture is input to a drain thereof.

16. A liquid crystal display apparatus comprising:

a liquid crystal layer disposed between a pair of substrates arranged in opposition to each other, at least one of said substrates being transparent;

a plurality of scanning electrode lines distributed in one of a pair of said substrates;

a plurality of display electrodes arranged within a plurality of display regions respectively surrounded by a plurality of said scanning electrode lines and a plurality of signal electrode lines in said one of said substrates;

opposed electrodes respectively arranged in opposition to said display electrodes across said liquid crystal layer;

first switching devices for static picture and second switching devices for motion picture arranged within a plurality of said display regions and connected to respective display electrodes;

static picture controlling circuit arranged within said plurality of display regions, for controlling respective ones of a plurality of said first switching devices for static picture on the basis of the signal from said each signal electrode line and said each scanning electrode line and static picture data;

motion picture controlling circuit arranged within said plurality of display regions, for controlling respective ones of a plurality of said second switching devices for motion picture on the basis of the signal from said each signal electrode line and said each scanning electrode line and motion picture data;

wherein for displaying a static picture, the signal from said signal electrode line and said scanning electrode line and said static picture data is applied to said static picture controlling circuit in said static picture display region for placing said switching device for static picture in an ON state and holding static picture data, and supply of the signal from said signal electrode line and said scanning electrode line and said static picture data to the static picture control circuit holding the static picture data among said static picture controlling circuits in the static picture display region; and

wherein for displaying motion picture, the signal from said signal electrode line and said scanning electrode line and said motion picture data is applied to said motion picture controlling circuit in said motion picture display region for placing said second switching device for motion picture in an ON state and holding motion picture data.

17. A liquid crystal display apparatus comprising:

a pair of substrates arranged in opposition to each other, at least one of which is transparent;

a liquid crystal layer sandwiched between said pair of substrates;

a plurality of scanning electrode lines distributed on one of said pair of substrates;

a plurality of signal electrode lines distributed on the substrate, on which said scanning electrode lines are distributed and intersecting with said scanning electrode lines in matrix form;

a plurality of display electrodes respectively arranged in a plurality of display regions on one of said substrates respectively surrounded by said plurality of scanning electrode lines and said plurality of signal electrode lines;

a plurality of opposed electrode arranged in opposition to said plurality of display electrodes across said liquid crystal layer;

a plurality of picture data electrode lines arranged corresponding to said plurality of signal electrode lines and leading the picture data to said plurality of display regions;

a plurality of static picture switching devices respectively connected to a plurality of display electrodes;

a plurality of motion picture switching devices respectively connected to said plurality of display electrodes;

a plurality of static picture control circuits receiving signals from said plurality of signal electrode lines and said plurality of scanning electrode lines and static picture data from said plurality of picture data lines, holding said static picture data when a conditions of said signals and said static picture data satisfies an ON condition of said plurality of static picture switching devices, and controlling respective ones of said plurality of static picture switching devices into an ON state;

a plurality of motion picture control circuits receiving signals from said plurality of signal electrode lines and said plurality of scanning electrode lines and motion picture data from said plurality of picture data lines, and controlling respective ones of said plurality of motion picture switching devices into an ON state when a conditions of said signals and said motion picture data satisfies an ON condition of said plurality of motion picture switching devices;

a plurality of picture data selection circuits selecting the static picture data upon static picture display, selecting the motion picture data upon motion picture display and outputting the selected picture data to said plurality of picture data electrode lines, respectively;

motion picture display region designating means for designating a region for displaying motion picture among said plurality of display regions;

motion picture data outputting means for outputting motion picture data to only the picture data selecting circuit corresponding to the display region by a designation of said motion picture display region designating means among a plurality of picture data selecting circuits, according to designation of said motion picture display region designating means;

static picture scanning pulse outputting means for sequentially outputting scanning pulses for the designated scanning electrode lines among said plurality of scanning electrode lines upon static picture display;

motion picture scanning pulse outputting means for sequentially outputting scanning pulses for the designated scanning electrode lines among said plurality of scanning electrode lines upon motion picture display;

static picture liquid crystal drive signal outputting means for outputting a static picture liquid crystal drive signal to said plurality of signal electrode lines in synchronism with the scanning pulses by output of said static picture scanning pulse outputting means; and

motion picture liquid crystal drive signal outputting means for outputting a motion picture liquid crystal drive signal to designated signal electrode lines among a plurality of signal electrode lines in synchronism with the scanning pulses by output of said motion picture scanning pulse outputting means.

18. A liquid crystal display apparatus according to claim 17, wherein said motion picture liquid crystal drive signal outputting means sequentially outputs the motion picture data to the designated signal electrode lines depending upon the number of designated signal electrode lines in response to the scanning pulse when the scanning pulse is output to one of the scanning electrode line among the designated scanning electrode line.