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Constant current circuit and flat display device

A constant current circuit and circuit technology, applied in the direction of circuits, electric light sources, electrical components, etc., can solve problems such as increased power consumption, and achieve the effect of reducing changes

Inactive Publication Date: 2006-10-11
JAPAN DISPLAY INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this design has the disadvantage of increasing power consumption by a certain amount

Method used

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  • Constant current circuit and flat display device
  • Constant current circuit and flat display device

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Experimental program
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Embodiment 1

[0036] (1-1) Structure of Embodiment 1

[0037] FIG. 3 shows a block diagram of a liquid crystal display device according to Embodiment 1 of the present invention. In this liquid crystal display device 1 , each pixel is formed of a liquid crystal cell 2 , a polysilicon TFT 3 which is a switching device of the liquid crystal cell 2 , and a storage capacitor 4 , and the pixels are arranged in a matrix to form a display section 6 . In this liquid crystal display device 1, each pixel which forms a display portion 6 is connected to a horizontal driving circuit 7 and a vertical driving circuit 8 through a signal line LS and a gate line LG, so that pixels are sequentially selected by means of the vertical driving circuit 8. And according to the driving signal from the horizontal driving circuit 7, the gray level of each pixel is set to display a desired image.

[0038] Accordingly, the vertical drive circuit 8 sequentially selects pixels in row units in conjunction with the processi...

Embodiment 2

[0081] FIG. 14 shows a structural block diagram of an analog buffer circuit applied to a liquid crystal display according to Embodiment 2 of the present invention. The analog buffer circuit 40 is constructed of a PMOS source follower circuit instead of its analog buffer based on the NMOS source follower circuit according to Embodiment 1. Therefore, in the liquid crystal display according to Embodiment 2, precharge processing associated with switching between the ground potential and the negative predetermined potential is performed instead of the ground potential and the positive potential in the liquid crystal display device 1 according to Embodiment 1. Precharge processing associated with switching between predetermined potentials.

[0082]The analog buffer circuit 40 is constructed in the same manner as the analog buffer circuit 20 of Embodiment 1, except that its structure uses a PMOS transistor instead of an NMOS transistor, and except for the respective parts associated ...

Embodiment 3

[0086] FIG. 17 shows a structural block diagram of an analog buffer circuit applied to a liquid crystal display according to Embodiment 3 of the present invention. The analog buffer circuit 50 is constructed by a combination of an NMOS source follower circuit and a PMOS source follower circuit instead of its analog buffer based on the NMOS source follower circuit according to Embodiment 1. Therefore, in the liquid crystal display according to Embodiment 3, its precharge processing associated with switching between the ground potential and a negative predetermined potential is performed instead of its connection to the ground potential in the liquid crystal display device 1 according to Embodiment 1. Precharge processing associated with switching between positive predetermined potentials.

[0087] As shown in FIG. 18 , the analog buffer circuit is constructed by a combination of its source follower circuit using NMOS transistors according to Embodiment 1 and its source follower...

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Abstract

The invention is applied to, for example, a liquid crystal display device with which a driver circuit is integrally formed on an insulating substrate. A reference current II is used to charge a sampling capacitor C3. A gate-to-source voltage Vgs of a transistor Q14 generated by that reference current II is set to the sampling capacitor C3. Thereafter, the voltage Vgs of the sampling capacitor C3 is used to drive and cause the transistor Q14 to function as a constant current circuit.

Description

technical field [0001] The present invention relates to a constant current circuit and a flat panel display device and is applicable to, for example, a liquid crystal display device in which a driving circuit is integrally formed on an insulating substrate. Compared with the conventional structure, after charging the sampling capacitor with the reference current and setting the gate-source voltage of the transistor due to the reference current in the sampling capacitor, the present invention drives the transistor by means of the voltage of the sampling capacitor The variation can be reduced so that it functions as a constant current circuit. Background technique [0002] Conventionally, in various integrated circuits, a constant current circuit is constructed by a current mirror circuit in order to supply current required for each part to operate. Figures 1 and 2 show the wiring diagrams of their constant current circuits using current mirror circuits, respectively. The co...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G09G3/36G09G3/20H03K17/00H03K17/687G02F1/133H05B33/14G02F1/1345H01L51/50
CPCG09G2300/0408G09G2310/027G09G2310/0291G09G2330/021G09G2310/0272G09G3/3614G09G2310/08G09G2330/023G09G3/3688G09G2300/0876G09G2310/0248G09G3/20G09G3/36G02F1/133
Inventor 木田芳利仲岛义晴
Owner JAPAN DISPLAY INC
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