Liquid crystal display device

• US 8,508,484 B2
• Filed: 12/31/2009
• Issued: 08/13/2013
• Est. Priority Date: 01/27/2009
• Status: Expired due to Fees

• Current Assignee: Japan Display West Incorporated (Japan Display Incorporated)
• Original Assignee: Japan Display West Incorporated (Japan Display Incorporated)
• Inventors: Mizuhashi, Hiroshi, Yamauchi, Yuko, Koito, Takeo, Tanaka, Tsutomu, Hayashi, Shuji, Nakanishi, Takayuki, Nakajima, Yoshiharu
• Primary Examiner(s): Wang, Quan-Zhen
• Assistant Examiner(s): DAVIS, TONY O
• Application Number:
  US12/650,747
• Publication Number:
  US 20100188347A1
• Time in Patent Office: 1,321 Days
• Field of Search: 345172-173
• US Class Current: 345/172
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/13394 spacers regularly patterned on the cell subtrate, e.g. walls, pillars G02F1/133377 takes precedence
• CPC Class Codes: G02F 1/134372 for fringe field switching [FFS] where the common electrode is not patterned
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/047 using sets of wires, e.g. crossed wires

Abstract

An embodiment of the invention provides a liquid crystal display device, including a first substrate; a second substrate; a liquid crystal layer formed between the first substrate and the second substrate; a first sensor electrode formed on the first substrate; a second sensor electrode formed on the second substrate, and disposed so as to be adapted to contact the plurality of first sensor electrodes close to one another by pressing from a side of either the first substrate or the second substrate; and a sensor drive circuit for applying a voltage to a first wiring electrically connected to one of the plurality of first sensor electrodes which the second sensor electrode is adapted to contact by the pressing, and detecting a change in potential of a second wiring electrically connected to another one of the plurality of first sensor electrodes.

Claims

1. A liquid crystal display device, comprising:

a first substrate;

a second substrate;

a liquid crystal layer formed between said first substrate and said second substrate;

a display function region formed between the first substrate and the second substrate, the display function region having an image display function, and wherein a video signal is supplied from a signal line via a transistor in each pixel and a display pixel electrode is formed on the first substrate;

at least one short pixel electrode is formed on the second substrate such that by pressing on either the first substrate or the second substrate, a short is caused for two adjacent pixel electrodes via the short pixel electrode, and a sensor drive circuit detects a signal level change based on contact with the short pixel electrode.

2. The liquid crystal display device according to claim 1, wherein said first sensor electrode is a pixel electrode to which a video signal is supplied from corresponding one of signal lines through corresponding one of transistors within pixels in a phase of display, and

said second sensor electrode is at least one short-circuit piece through which the two pixel electrodes of the adjacent two pixels is adapted to be short-circuited in accordance with application of the pressing force.

3. The liquid crystal display device according to claim 2, wherein said first wiring and said second wiring are signal lines which are connected to said pixel electrode provided every pixel through corresponding one of said transistors.

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

a common electrode for driving said liquid crystal layer based on a potential difference caused between a voltage of the pixel electrode provided every pixel and a voltage of said common electrode;

wherein said sensor drive circuit makes said second wiring in a floating state after the same voltage as a common voltage by which said common electrode is driven is set in said first wiring, and an inversed voltage of the common voltage is applied to said second wiring.

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

a common electrode for driving said liquid crystal layer based on a potential difference caused between a voltage of the pixel electrode provided every pixel and a voltage of said common electrode;

wherein said sensor drive circuit makes said second wiring in a floating state after a first voltage, having the same polarity as that of a common voltage by which said common electrode is driven, which is different from the common voltage is set in said first wiring, and a second voltage having a potential difference between the first voltage and the second voltage which is smaller than that between an inversed voltage of the common voltage and the common voltage is set in said second wiring.

6. The liquid crystal display device according to claim 1, wherein said sensor drive circuit comprises:

a voltage setting portion for applying a voltage to said first wiring;

a wiring controlling portion for making said second wiring in a floating state in a state in which there is a potential difference between the voltage and a voltage of said second wiring in the floating state; and

a read portion for reading that the plurality of first sensor electrodes are electrically connected to each other through said second sensor electrode from a change in potential of said second wiring in the floating state.

7. The liquid crystal display device according to claim 1, wherein said sensor drive circuit serves as a circuit as well for carrying out display write control following sensor drive control, and

said sensor drive circuit uses a voltage of said first wiring as a reference voltage in a phase of the display write control, and sets the reference voltage in said second wiring prior to the write.

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

a pixel array having pixels disposed in a matrix; and

a write circuit for controlling supply of video signals from plural M video signal lines to said pixel array through an M-phase drive switch circuit;

wherein said sensor drive circuit receives supply of the voltage for said first wiring from one of different two video signal lines of the M video signal lines driven by said write circuit, makes said second wiring connected to the other of the different two video signal lines in a floating state by separating said second wiring from said write control circuit by said M-phase drive switch circuit, and detects a change in potential based on a contact between the sensor electrodes in said second wiring in the floating state.