Flat-panel display device and electronic apparatus

• US 8,928,620 B2
• Filed: 08/04/2008
• Issued: 01/06/2015
• Est. Priority Date: 08/07/2007
• Status: Active Grant

• Current Assignee: NLT Technologies, Ltd. (Tianma Microelectronics Company Limited)
• Original Assignee: NLT Technologies, Ltd. (Tianma Microelectronics Company Limited)
• Inventors: Haga, Hiroshi
• Primary Examiner(s): Ngo, Tony N
• Application Number:
  US12/185,489
• Publication Number:
  US 20090040192A1
• Time in Patent Office: 2,346 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 scanning and signal electrodes for applying electrical signals to an electro-optically responsive display element and pixel electrodes;

a display area formed by an array of the pixel electrodes;

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

a current detecting circuit that detects currents that flow through the impedance surface;

a detector that detects whether a touch occurs and coordinates of the touch based on the currents detected by said current detecting circuit;

wherein, while said current detecting circuit detects the currents, at least one of said scanning and signal electrodes for applying electrical signals, which extends from an exterior to an interior of the display area for transmitting an electrical signal from the exterior to the interior of the display area, from among the scanning and signal electrodes that apply the electrical signals to the display element, is placed directly at a high impedance against all voltage sources so as to enable to decrease the currents flowing through the impedance surface and low impedance scanning and signal electrodes other than the at least one of the scanning and signal electrodes placed at 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 while said current detecting circuit detects currents.

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;

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

wherein outputs of a first driving circuit for driving the scanning lines and outputs of a second driving circuit for driving the signal lines attain a high impedance while said current detecting circuit detects currents.

5. The device according to claim 4, wherein said display device substrate has capacitors one ends of which are connected to the switch elements and the 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 against all voltage sources by controlling switching of the capacitor lines while said current detecting circuit detects currents.

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 currents 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 currents at the corresponding location.

12. The device according to claim 1, further comprising:

an indicating member connected to an AC voltage source for supplying current to any position on the impedance surface;

a wiring connected to the indicating member; and

an AC voltage source connected to the wiring.

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.

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

17. A flat-panel display device comprising:

an electro-optically responsive display element;

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

a display area formed by an array of the pixel electrodes; 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 has an impedance surface,

wherein said flat-panel display device further comprises a current detecting circuit that detects currents that flow through the impedance surface, and

wherein, while said current detecting circuit detects the currents, at least one of said scanning and signal electrodes for applying electrical signals, which extends from an exterior to an interior of the display area for transmitting an electrical signal from the exterior to the interior of the display area, from among the scanning and signal electrodes that apply the electrical signals to the display element, is placed directly at a high impedance against all voltage sources so as to enable to decrease the currents flowing through the impedance surface and-low impedance scanning and signal electrodes other than the at least one of the scanning and signal electrodes placed at high impedance.

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

19. A flat-panel display device comprising:

an electro-optically responsive display element;

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

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

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

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

wherein said flat-panel display device further comprises a current detecting circuit that detects currents that flow through the impedance surface, and

wherein while said current detecting circuit detects the currents, at least one of said scanning and signal electrodes for applying electrical signals, which extends from an exterior to an interior of the display area for transmitting an electrical signal from the exterior to the interior of the display area, from among the scanning and signal electrodes that apply the electrical signals to the display element, is placed directly at a high impedance against all voltage sources so as to enable to decrease the currents flowing through the impedance surface and-low impedance scanning and signal electrodes other than the at least one of the scanning and signal electrodes placed at high impedance.

20. An electronic apparatus on which the flat-panel display device set forth in claim 19 is mounted.

21. A flat-panel display device comprising:

a display device substrate having a plurality of scanning lines, a plurality of signal lines, pixel electrodes formed in the vicinity of crosspoints of said scanning lines and said signal lines, and switch elements comprising a TFT and switching electric connection with said pixel electrodes and said signal lines;

a first voltage source supplied to an output of the scanning lines;

a second voltage source supplied to an output of the signal lines;

a display area formed of an array of said pixel electrodes;

an impedance surface corresponding to said display area;

a display element being carried and sandwiched between said display device substrate to said impedance surface, and responding electro-optically; and

a current detecting circuit detecting currents that flow through said impedance surface;

wherein, while said current detecting circuit detects the currents, at least one of said scanning lines and said signal lines is placed directly at a high impedance against all voltage sources so as to enable to decrease the currents flowing through the impedance surface and-low impedance scanning lines and signal lines other than the at least one of said scanning lines and said signal lines placed at high impedance.

22. A flat panel display device comprising:

a display device substrate formed to have scanning and signal 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;

a current detecting circuit that detects currents that flow through the impedance surface and supplies its output to a position detecting circuit that detects whether a touch occurs and coordinates of the touch;

wherein, while said current detecting circuit detects the currents, at least one of said scanning and signal electrodes-for applying electrical signals for transmitting an electrical signal from an exterior to an interior of the display area, from among the scanning and signal electrodes for applying the electrical signals to the display element, is placed directly at a high impedance against all voltage sources so as to enable to decrease the currents flowing through the impedance surface and low impedance scanning and signal electrodes other than the at least one of the scanning and signal electrodes placed at high impedance,

wherein said display device substrate has a plurality of scanning lines and a plurality of signal lines formed on a substrate, switch elements comprising a TFT and formed in the vicinity of crosspoints of said scanning lines and signal lines and pixel electrodes connected to said switch elements,

wherein the display area is formed by an array of said pixel electrodes,

wherein outputs of a first driving circuit for driving the scanning lines and outputs of a second driving circuit for driving the signal lines attain a high impedance while said current detecting circuit detects current, and

wherein the impedance surface is opposite to the scanning line and the signal line.