LIQUID CRYSTAL DEVICE AND ELECTRONIC APPARATUS

• US 20090015533A1
• Filed: 06/25/2008
• Published: 01/15/2009
• Est. Priority Date: 06/29/2007
• Status: Active Grant

• Current Assignee: Japan Display West Incorporated (Japan Display Incorporated)
• Original Assignee: Epson Imaging Devices Corporation (Seiko Group)
• Inventors: KATO, Tomotoshi, SHIRAGAMI, Kengo, FUJITA, Shin
• Granted Patent: US 8,456,400 B2
• Time in Patent Office: Days
• US Class Current: 345/92
• CPC Class Codes: G02F 1/1362 Active matrix addressed cells G02F1/134336, G02F1/134363 take precedence
• 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 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors

Abstract

A liquid crystal device including a plurality of scanning lines, a plurality of data lines, a plurality of pixel electrodes, a capacitor electrode, a control circuit, a scanning line driving circuit, and a data line driving circuit.

Claims

1. A liquid crystal device comprising:

a plurality of scanning lines;

a plurality of data lines that intersect with the scanning lines;

a plurality of pixel electrodes that are provided at positions corresponding to intersections of the plurality of scanning lines and the plurality of data lines;

a capacitor electrode that is provided opposite each of the pixel electrodes and that forms a capacitor with each of the pixel electrodes or with an electrode layer connected to each of the pixel electrodes;

a control circuit that alternately supplies the capacitor electrode with a first voltage or a second voltage that is higher in electric potential than the first voltage;

a scanning line driving circuit that sequentially supplies the plurality of scanning lines with a scanning line selection voltage that selects the scanning line; and

a data line driving circuit that, when the scanning line is selected, alternately supplies the plurality of data lines with a positive polarity image signal that is higher in electric potential than the first voltage or a negative polarity image signal that is lower in electric potential than the second voltage, wherein

the control circuit includes a selection circuit and a selection signal output circuit, wherein

the selection circuit alternately selects and outputs the first voltage or the second voltage to the capacitor electrode, wherein

the selection signal output circuit outputs a selection signal to the selection circuit, and wherein

the first voltage is higher in electric potential than a low electric potential of the selection signal, and the second voltage is lower in electric potential than a high electric potential of the selection signal.

2. The liquid crystal device according to claim 1, further comprising:

a pair of substrates that hold a liquid crystal, wherein

the control circuit is formed of transistors formed on any one of the substrates, and wherein

a difference in electric potential between a gate and a source of each transistor that constitutes the selection circuit is set lower than a difference in electric potential between a gate and a source of each transistor that constitutes the selection signal output circuit.

3. The liquid crystal device according to claim 1, further comprising:

a pair of substrates that hold a liquid crystal, wherein

the control circuit is formed of transistors formed on any one of the substrates, and wherein

a gate length of each transistor that constitutes the selection circuit is set shorter than a gate length of each transistor that constitutes the selection signal output circuit.

4. The liquid crystal device according to claim 1, wherein the capacitor electrode is a common electrode.

5. The liquid crystal device according to claim 1, wherein the capacitor electrode is an auxiliary capacitor electrode.

6. The liquid crystal device according to claim 4, further comprising:

a first substrate that includes the plurality of scanning lines, the plurality of data lines, the plurality of pixel electrodes that are provided at positions corresponding to intersections of the plurality of scanning lines and the plurality of data lines, and the opposite electrode provided opposite the pixel electrodes;

a second substrate that is opposed to the first substrate; and

a liquid crystal that is provided between the first substrate and the second substrate, wherein

after the control circuit supplies the first voltage to the common electrode, the scanning line driving circuit supplies the selection voltage to the scanning line and the data line driving circuit supplies the positive polarity image signals to the data lines,

while, after the control circuit supplies the second voltage to the common electrode, the scanning line driving circuit supplies the selection voltage to the scanning line and the data line driving circuit supplies the negative polarity image signals to the data lines.

7. The liquid crystal device according to claim 4, further comprising:

a first substrate that includes the plurality of scanning lines, the plurality of data lines, the plurality of pixel electrodes that are provided at positions corresponding to intersections of the plurality of scanning lines and the plurality of data lines, and the opposite electrode provided opposite the pixel electrodes;

a second substrate that is opposed to the first substrate;

a liquid crystal that is provided between the first substrate and the second substrate; and

a data line driving circuit that, when the scanning line is selected, alternately supplies the plurality of data lines with positive polarity image signals that are higher in electric potential than the first voltage or negative image signals that are lower in electric potential than the second voltage, wherein

when the electric potentials of the data lines correspond to writing of positive polarity image signals in a case where the scanning line is set to an on electric potential, the control circuit supplies the auxiliary capacitor electrode with the second voltage after the scanning line is changed to an off electric potential,

while, on the other hand, when the electric potentials of the data lines correspond to writing of negative polarity image signals in a case where the scanning line is set to an on electric potential, the control circuit supplies the auxiliary capacitor electrode with the first voltage after the scanning line is changed to an off electric potential.

8. An electronic apparatus comprising the liquid crystal device according to claim 1.