Touch sensitive display device

• US 20070046639A1
• Filed: 10/12/2004
• Published: 03/01/2007
• Est. Priority Date: 10/13/2003
• Status: Active Grant

• Current Assignee: Anders Swedin
• Original Assignee: Integritouch Development AB
• Inventors: Swedin, Anders
• Granted Patent: US 7,705,834 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/1343 Electrodes reflective electrodes G02F1/133553
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G09G 3/04 for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions

Abstract

A touch sensor is disclosed comprising a display device having a substrate on which substrate at least one display electrode is disposed for the display of a shape on the display device. An interface is coupled to the at least one display electrode for receiving display data to the display device. Moreover is a measuring circuit coupled to the at least one display electrode. Switching means are provided for connecting the interface to the at least one display electrode when the switching means is in a first state of operation and connecting the measuring circuit to the at least one display electrode when the switching means is in a second state of operation.

Claims

1. A touch sensor, comprising:

a display device having at least one substrate on which at least one display electrode is disposed for the display of a shape on the display device;

an interface (21) coupled to the at least one display electrode (11) for receiving display data to the display device;

a measuring circuit coupled to the at least one display electrode; and

switching means for connecting the interface to the at least one display electrode when the switching means is in a first state of operation and for connecting the measuring circuit to the at least one display electrode when the switching means in is a second state of operation.

2. A touch sensor according to claim 1, wherein the measuring circuit comprises a capacitance measuring circuit.

3. A touch sensor according to claim 1, wherein the measuring circuit comprises a resistance measuring circuit.

4. A touch sensor according to claim 1, wherein the measuring circuit comprises:

a signal generator coupled to the at least one display electrode for providing a predetermined test signal to the display electrode; and

a signal evaluating circuit coupled to the at least one display electrode for receiving the test signal from the signal generator.

5. A touch sensor according to claim 4, wherein the signal evaluation circuit is adapted configured to detect a deviation in the test signal when the switching means is in the second state of operation.

6. A touch sensor according to claim 4, wherein:

the display device comprises a front substrate having a plurality of segments; and

the signal generator is adapted configured to apply the test signal to the segments on the front substrate.

7. A touch sensor according to claim 4, wherein:

the display device comprises a back substrate having a plurality of segments; and

the signal generator is configured to apply the test signal to segments on the back substrate.

8. A touch sensor according to claim 6, wherein the segments on the front substrate which are not connected to the signal generator are retained in a high-ohmic state.

15. A touch sensor according to claim 5, wherein:

the display device comprises a front substrate having a plurality of segments; and

the signal generator is adapted to apply the test signal to the segments on the front substrate.

16. A touch sensor according to claim 5, wherein:

the display device comprises a back substrate having a plurality of segments; and

the signal generator is adapted to apply the test signal to the segments on the back substrate.

17. A touch sensor according to claim 7, wherein the segments on the back substrate which are not connected to the signal generator are retained in a high-ohmic state.

9. A method for detecting a touch on a display device, said display device having a substrate on which at least one display electrode is disposed, wherein said display electrode is coupled to an interface for receiving display data to the display device, comprising the steps of:

disconnecting the at least one display electrode from the interface;

connecting said display electrode to a measuring circuit; and

detecting a change in an electrical property of the display electrode due to an electrical coupling with an object touching the display device in the vicinity of the display electrode.

10. A method according to claim 9, wherein detecting a change in an electrical property of the display electrode comprises:

applying a predetermined test signal to the display electrode and detecting a deviation in the test signal due to an electrical coupling with an object touching the display device in the vicinity of the display electrode.

11. A method according to claim 9, wherein the electrical coupling comprises a capacitive coupling.

12. A method according to claim 9, wherein the electrical coupling comprises a galvanic coupling.

13. A method according to claim 10, wherein the electrical coupling comprises a capacitive coupling.

14. A method according to claim 10, wherein the electrical coupling comprises a galvanic coupling.