Liquid crystal device, electronic apparatus and position identification method for identifying a position of an object

• US 8,599,146 B2
• Filed: 02/26/2008
• Issued: 12/03/2013
• Est. Priority Date: 03/13/2007
• Status: Active Grant

• Current Assignee: Japan Display West Incorporated (Japan Display Incorporated)
• Original Assignee: Japan Display West Incorporated (Japan Display Incorporated)
• Inventors: Utsunomiya, Sumio, Koshihara, Takeshi
• Primary Examiner(s): Amadiz, Rodney
• Application Number:
  US12/037,590
• Publication Number:
  US 20080224971A1
• Time in Patent Office: 2,107 Days
• Field of Search: 345/104, 345156-158, 345173-174, 345/179, 178 1801- 1903, 178/20.04, 349/12
• US Class Current: 345/173
• 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 first substrate;

a second substrate opposed to the first substrate;

a liquid crystal sealed in a gap between the first substrate and the second substrate;

an opposite electrode having a voltage which periodically varies;

a plurality of detection electrodes, an initial voltage being induced in each of the plurality of detection electrodes based on a variation in the voltage of the opposite electrode;

a switching circuit configured to enable the production of a detection signal by sequentially connecting each of the plurality of detection electrodes which are being induced with the initial voltage based on the variation in the voltage of the opposite electrode; and

a position identification device configured to, using the detection signal produced by sequentially connecting each of the plurality of detection electrodes which are being induced with the initial voltage based on the variation in the voltage of the opposite electrode, generate a position signal that indicates a position of a pointing body.

2. The liquid crystal device of claim 1, wherein the position identification device is configured to generate the position signal based on 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 of claim 1, which includes an electric discharge device configured to, 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, discharge electric charge stored in the corresponding one of the detection electrodes.

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

5. The liquid crystal device of claim 1, wherein the plurality of detection electrodes are:

(a) formed on a side of the first substrate, which is opposite to a side on which the liquid crystal is provided; and

(b) opposed to the opposite electrode via the first substrate.

6. An electronic apparatus comprising:

a liquid crystal device including;

(a) a first substrate;

(b) a second substrate opposed to the first substrate;

(c) a liquid crystal sealed in a gap between the first substrate and the second substrate;

(d) an opposite electrode having a voltage which periodically varies;

(e) a plurality of detection electrodes, an initial voltage being induced in each of the plurality of detection electrodes based on a variation in the voltage of the opposite electrode;

(f) a switching circuit configured to enable the production of a detection signal by sequentially connecting each of the plurality of detection electrodes which are being induced with the initial voltage based on the variation in the voltage of the opposite electrode; and

(g) a position identification device configured to, using the detection signal produced by sequentially connecting each of the plurality of detection electrodes which are being induced with the initial voltage based on the variation in the voltage of the opposite electrode, generate a position signal that indicates a position of a pointing body.

7. A method of identifying a position of a pointing body in a liquid crystal device that includes a first substrate;

a second substrate opposed to the first substrate;

a liquid crystal sealed in a gap between the first substrate and the second substrate;

an opposite electrode having a voltage which periodically varies;

a plurality of detection electrodes, an initial voltage being introduced in each of the plurality of detection electrodes based on the a variation in the voltage of the opposite electrode, the method comprising;

(a) causing a switching circuit to enable the production of a detection signal by sequentially connecting each of the plurality of detection electrodes which are being induced with the initial voltage based on the variation in the voltage of the opposite electrode; and

(b) using the detection signal produced by sequentially connecting each of the plurality of detection electrodes which are being induced with the initial voltage based on the variation in the voltage of the opposite electrode to generate a position signal that indicates a position of the pointing body.