Display device and driving method thereof

• US 6,873,320 B2
• Filed: 09/05/2001
• Issued: 03/29/2005
• Est. Priority Date: 09/05/2000
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nakamura, Takashi
• Primary Examiner(s): Nguyen, Jimmy H.
• Application Number:
  US09/945,826
• Publication Number:
  US 20020036625A1
• Time in Patent Office: 1,301 Days
• Field of Search: 345/87, 345/89, 345/90, 345/92, 345/96, 345 98-100, 345/103, 345/204, 345/691, 345/692, 345/694, 345/209, 345/214
• US Class Current: 345/204
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• 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 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3618 with automatic refresh of the display panel using sense/write circuits
• CPC Class Codes: G09G 3/3666 with the matrix divided into sections

Abstract

A liquid crystal display device which can reduce power consumption and can be miniaturized. The liquid crystal display device according to the present invention includes a pixel array portion, an address decoder, a display memory (VRAM), and a VRAM controller, and transmits/receives a signal to/from a CPU and a peripheral circuit through a system bus. The pixel array portion has an area gradation pixel structure in which each pixel is composed of a plurality of one-bit memories. The entire pixel array portion is divided into pixel blocks each of which consists of a plurality of pixels, and the one-bit memory is rewritten in units of block. The one-bit memory has a double-word line structure.

Claims

1. A display device comprising:

a plurality of display pixels arranged in a matrix form;

a plurality of scanning lines arranged in a row direction of said display pixels;

data lines arranged in a column direction of said display pixels;

a data line driving circuit configured to supply image data to said data lines;

a scanning line driving circuit configured to supply a scanning signal to said scanning lines; and

a controller configured to control said data line driving circuit and said scanning line driving circuit,

wherein each of said display pixels includes;

a plurality of data bit storages which store the corresponding image data in response to the scanning signal;

a holding circuit which holds one bit data in the image data stored in said plurality of data bit storages, and conducts refresh operation for said plurality of data bit storages;

a lighting controller which controls whether or not to light the display pixels in accordance with a logic of one bit data held in said holding circuit; and

a transferring transistor connected between said plurality of data bit storages and said holding circuit,

said holding circuit includes;

two inverters connected in series; and

a feedback transistor connected between an output terminal of the inverter at a subsequent stage and an input terminal of the inverter at a previous stage,

wherein said plurality of display pixels are divided into two or more blocks in each of horizontal and vertical directions, and said display pixels are configured to update image data based on a signal which is transmitted from said controller, said signal including an indicator designating a block for display updating and the pixel data in the block.

2. The display device according to claim 1, wherein said display pixel includes a polarity inverting circuit configured to invert polarity of a pixel voltage based on the corresponding data held in said data bit storages with respect to a reference voltage in a predetermined cycle.

3. The display device according to claim 2, wherein said predetermined cycle is determined based on said scanning signal.

4. The display device according to claim 2, wherein said polarity inverting circuit is connected to a pair of control wirings arranged in the row or column direction, and inverts the polarity based on the control signal inputted to said control wirings.

5. The display device according to claim 4, wherein a pair of said polarity inverting circuits adjacent to each other in a direction orthogonal to said control wirings are commonly connected to a pair of said control wirings.

6. The display device according to claim 1, further comprising:

a plurality of column selection lines arranged in the column direction corresponding to said blocks;

a column selection line driving circuit configured to supply a selection signal to said column selection line;

a sub scanning line arranged in accordance with said display pixels arranged adjacent to each other in the row direction in said block; and

a selection controller configured to supply a sub scanning signal to said sub scanning line based on a selection signal supplied to said column selection line and a scanning signal supplied to said scanning line.

7. The display device according to claim 1, wherein said controller supplies a group of the corresponding data of each of said display pixel in said block to be changed, to said data line driving circuit and said signal line driving circuit together with address data of said block.

8. The display device according to claim 1, wherein a pair of said display pixels arranged adjacent to each other in said column direction in said block are commonly arranged in accordance with one of said data lines.

9. The display device according to claim 1, wherein said display pixel is formed by holding a light emitting layer between a pair of electrodes.

10. The display device according to claim 1, wherein said display pixel is formed by holding a liquid crystal layer between a pair of electrodes.

11. The display device according to claim 1, further comprising:

a level shift circuit which shifts signal level of a data signal inputted from outside at low amplitude, wherein the level-shifted data signal is supplied to said data bit storage through said data lines.

12. The display device according to claim 1, wherein said plurality of display pixels are divided into a plurality of blocks having two or more blocks in horizontal direction and two or more blocks in vertical direction, and update pixel data by receiving a signal designating the block for display updating transmitted from said control circuit and the image data of the corresponding block;

said scanning line drive circuit is arranged at both of left side and right side; and

said data bit storage has a capacitor, a writing transistor and a read-out transistor.