FLAT- PANEL DISPLAY DEVICE AND ELECTRONIC APPARATUS

• US 20090040192A1
• Filed: 08/04/2008
• Published: 02/12/2009
• Est. Priority Date: 08/07/2007
• Status: Active Grant

• Current Assignee: NLT Technologies, Ltd. (Tianma Microelectronics Company Limited)
• Original Assignee: NEC LCD Technologies Limited (Tianma Microelectronics Company Limited)
• Inventors: HAGA, Hiroshi
• Granted Patent: US 8,928,620 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06F 3/0444 using a single conductive element covering the whole sensing surface, e.g. by sensing the electrical current flowing at the corners

Abstract

A combination flat-panel touch sensor/display device includes a display device substrate on which signal lines, scanning lines and storage capacitance lines for applying electrical signals to liquid crystal are formed. A surface of the flat-panel display device corresponding to a display area has a transparent conductive film serving as an impedance surface. The device further includes current detecting circuits for detecting currents that flow through the impedance surface. In an interval over which the current detecting circuits detect current, at least one of the signal lines, scanning lines and storage capacitance lines is placed at a high impedance. The device reduces thickness without decline in display characteristics.

Claims

1. A flat-panel display device comprising:

a display device substrate formed to have electrodes for applying electrical signals to an electro-optically responsive display element;

an impedance surface corresponding to a display area of said flat-panel display device; and

a current detecting circuit that detects a current that flows through the impedance surface;

wherein in an interval over which said current detecting circuit detects current, at least one electrode for transmitting an electrical signal from the exterior to the interior of the display area from among the electrodes that apply the electrical signals to the display element is placed at a high impedance.

2. The device according to claim 1, further comprising a switch disposed on an electrode for transmitting an electrical signal from the exterior to the interior of the display area.

3. The device according to claim 2, comprising a control circuit for controlling switching of said switch;

wherein said control circuit controls at least one electrode for transmitting an electrical signal from the exterior to the interior of the display area to a high impedance in an interval over which said current detecting circuit detects current.

4. The device according to claim 1, wherein said display device substrate has a plurality of scanning lines and a plurality of signal lines formed on a substrate, switch elements formed in the vicinity of crosspoints of said scanning lines and signal lines and pixel electrodes connected to said switch elements;

a display area is formed by an array of said pixel electrodes; and

a first driving circuit for driving the scanning lines and a second driving circuit for driving the signal lines attain a high impedance in an interval over which said current detecting circuit detects current.

5. The device according to claim 3, wherein said display device substrate has capacitors one ends of which are connected to the switching elements and pixel electrodes, and capacitor lines that are connected to the other ends of the capacitors and extend to the exterior of the display area;

the capacitor lines being controlled to a high impedance by controlling switching of the capacitor lines in an interval over which said current detecting circuit detects current.

6. The device according to claim 5, wherein the capacitor lines also serve as scanning lines.

7. The device according to claim 1, wherein the impedance surface is formed on an opposing substrate that opposes the display device substrate via the display element.

8. The device according to claim 1, wherein the display element is any one selected from the group consisting of liquid crystal, an electrophoretic element, a charged particle, electrochromic material, gas, semiconductor and phosphor.

9. The device according to claim 1, wherein the display element has liquid crystal as its main component, and the impedance surface comprises a transparent conductive film.

10. The device according to claim 1, wherein said current detecting circuit applies AC voltage upon the impedance surface and detects a current that flows through the impedance surface owing to application of the AC voltage.

11. The device according to claim 10, wherein a plurality of said current detecting circuits are provided in correspondence with a plurality of locations of the impedance surface, and each current detecting circuit applies an AC voltage from the corresponding location and detects a current at the corresponding location.

12. The device according to claim 1, further comprising an indicating member for supplying current to any position on the impedance surface.

13. The device according to claim 1, further comprising a position detecting circuit that detects coordinates of point of contact of a contacting body with the impedance surface based upon an output signal from said current detecting circuit.

14. The device according to claim 2, wherein a flexible material is used for material forming the display device substrate and opposing substrate.

15. The device according to claim 1, wherein a linearization pattern is formed on the impedance surface.

18. An electronic apparatus on which the flat-panel display device set forth in claim 1 has been mounted.

16. A flat-panel display device comprising:

an electro-optically responsive display element;

a display device substrate on which electrodes for applying first electrical signals to said display element are formed;

an opposing substrate on which an impedance surface for applying second electrical signals to said display element is formed; and

a current detecting circuit that detects a current that flows through the impedance surface;

wherein said display device substrate and said opposing substrate are arranged so as to oppose each other via said display element; and

a linearization pattern is formed on the impedance surface.

19. An electronic apparatus on which the flat-panel display device set forth in claim 16 has been mounted.

17. A flat-panel display device comprising:

an electro-optically responsive display element;

a display device substrate on which electrodes for applying electrical signals to said display element are formed; and

an opposing substrate disposed at a position opposing said display device substrate via said display element;

wherein a surface of said display device substrate on a side thereof opposite said opposing substrate or a surface of said opposing electrode on a side thereof opposite said display device substrate has an impedance surface;

said flat-panel display device further comprising a current detecting circuit that detects a current that flows through the impedance surface.

20. An electronic apparatus on which the flat-panel display device set forth in claims 17 has been mounted.