LIQUID CRYSTAL DEVICE, ELECTRONIC APPARATUS AND POSITION IDENTIFICATION METHOD

• US 20080224971A1
• Filed: 02/26/2008
• Published: 09/18/2008
• Est. Priority Date: 03/13/2007
• Status: Active Grant

• Current Assignee: Japan Display West Incorporated (Japan Display Incorporated)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: UTSUNOMIYA, Sumio, KOSHIHARA, Takeshi
• Granted Patent: US 8,599,146 B2
• Time in Patent Office: Days
• US Class Current: 345/87
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A liquid crystal device includes a liquid crystal panel, a plurality of detection electrodes, a switching circuit, and a position identification device. The liquid crystal panel is configured so that a liquid crystal is sealed in a gap between a first substrate and a second substrate, which are opposed to each other, and a voltage of an opposite electrode opposite the liquid crystal periodically varies. The plurality of detection electrodes are provided on a side opposite to a side on which the liquid crystal is provided via the first substrate, wherein an initial voltage is induced in each of the plurality of detection electrodes on the basis of a variation in voltage of the opposite electrode. The switching circuit sequentially connects each of the plurality of detection electrodes, in which the initial voltages are induced, to a detection portion. The position identification device generates a position signal that indicates a position of a pointing body on the basis of a detection signal produced in the detection portion.

Claims

1. A liquid crystal device comprising:

a liquid crystal panel that is configured so that a liquid crystal is sealed in a gap between a first substrate and a second substrate, which are opposed to each other, and a voltage of an opposite electrode opposite the liquid crystal periodically varies;

a plurality of detection electrodes that are provided on a side opposite to a side on which the liquid crystal is provided via the first substrate, wherein an initial voltage is induced in each of the plurality of detection electrodes on the basis of a variation in voltage of the opposite electrode;

a switching circuit that sequentially connects each of the plurality of detection electrodes, in which the initial voltages are induced, to a detection portion; and

a position identification device that generates a position signal that indicates a position of a pointing body on the basis of a detection signal produced in the detection portion.

2. The liquid crystal device according to claim 1, wherein the position identification device is configured to generate the position signal on the basis of the length of time during which a voltage of the detection signal is outside a predetermined range because of the detection electrode being connected to the detection portion.

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

an electric discharge device that, when a voltage of the detection signal is first changed to go outside a predetermined range by connecting a corresponding one of the detection electrodes to the detection portion and then changed to fall within the predetermined range, discharges electric charge stored in the corresponding one of the detection electrodes.

4. The liquid crystal device according to claim 1, wherein the opposite electrode is continuously formed over the entire surface of the first substrate, which is opposite the liquid crystal.

5. The liquid crystal device according to claim 1, wherein the plurality of detection electrodes are formed on a side of the first substrate, which is opposite to a side on which the liquid crystal is provided, and are opposed to the opposite electrode via the first substrate.

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

7. A method of identifying a position of a pointing body in a liquid crystal device that includes a liquid crystal panel and a plurality of detection electrodes, wherein the liquid crystal panel is configured so that a liquid crystal is sealed in a gap between a first substrate and a second substrate, which are opposed to each other, and a voltage of an opposite electrode that is opposite the liquid crystal periodically varies, wherein the plurality of detection electrodes are provided on a side opposite to a side on which the liquid crystal is provided via the first substrate, wherein an initial voltage of each of the plurality of detection electrodes is induced on the basis of a variation in voltage of the opposite electrode, the method comprising:

sequentially connecting each of the plurality of detection electrodes, in which the initial voltages are induced, to a detection portion; and

generating a position signal that indicates a position of the pointing body on the basis of a detection signal produced in the detection portion.