ELECTRODE ARRANGEMENT FOR DISPLAY DEVICE

• US 20120081328A1
• Filed: 06/15/2010
• Published: 04/05/2012
• Est. Priority Date: 06/24/2009
• Status: Active Grant

• Current Assignee: Microchip Technology Germany GmbH (Microchip Technology Incorporated)
• Original Assignee: Microchip Technology Germany GmbH (Microchip Technology Incorporated)
• Inventors: Kandziora, Thomas, Fasshauer, Peter
• Granted Patent: US 8,487,905 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04107 Shielding in digitiser, i.e. guard or shielding arrangements, mostly for capacitive touchscreens, e.g. driven shields, driven grounds
• 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
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: Y10T 29/4913 Assembling to base an electrical component, e.g., capacitor, etc.

Abstract

The invention provides an electrode arrangement for a capacitive sensor device and for a capacitive sensor, respectively, for detecting a position and/or an approach of an object, which comprises a sensor electrode and a first shield electrode, wherein the sensor electrode is arranged on a first side of a substantially flat substrate with a first side and a second side, and wherein the first shield electrode is arranged on the second side of the substrate and serves for shielding the alternating electric field emitted by the sensor electrode from ground. There is also provided a foil with an electrode arrangement according to the invention as well as a method for the production of a display arrangement with an electrode arrangement according to the invention.

Claims

1. An electrode arrangement for a capacitive sensor for detecting a position or an approach of an object, the electrode arrangement comprising

a substantially flat substrate;

a sensor electrode on a first side of the substantially flat substrate with a first side and a second side, and

a first shield electrode on the second side of the substrate and serving for shielding the alternating electric field emitted by the sensor electrode from ground.

2. The electrode arrangement according to claim 1, further comprising

a second shield electrode on the first side of the substrate and couplable by a conductor path on the first side of the substrate, with evaluation electronics, the second shield electrode being arranged between the sensor electrode and the conductor path and at a spacing from the sensor electrode and from the conductor path and serving for shielding an alternating electric field emitted by the sensor electrode against the conductor path, the sensor electrode, the second shield electrode and the conductor path each being stripe-shaped, the second shield electrode being larger than the conductor path.

3. The electrode arrangement according to claim 2, wherein the sensor electrode is larger than the conductor path.

4. The electrode arrangement according to claim 2, wherein the sensor electrode is larger than the second shield electrode.

5. The electrode arrangement according to claim 2, further comprising

a third shield electrode on the first side of the substrate at a spacing from the conductor path, the conductor path being arranged between the second shield electrode and the third shield electrode.

6. The electrode arrangement according to claim 5, wherein the sensor electrode, the second shield electrode and the conductor path are substantially parallel to each other.

7. The electrode arrangement according to claim 1, wherein the first shield electrode is formed by a conductive and to generally transparent material.

8. The electrode arrangement according to claim 5, wherein

the sensor electrode is coupled with a resonance circuit,

the system formed including the sensor electrode and the resonance circuit can be applied with an electric voltage, and

a phase shift of an electric voltage of the resonance circuit compared to the electric voltage applied is indicative for the approach or the position of the object at the sensor electrode.

9. The electrode arrangement according to claim 8, wherein an output of the system formed including the sensor electrode and the resonance circuit is switchable by amplifying circuit on at least one of the three shield electrodes, in order to bring at least one of the three shield electrodes substantially to the electric potential of the sensor electrode.

10. The electrode arrangement according to claim 9, wherein

the amplifying circuit is a driver circuit, and

the driver circuit is adapted to drive the current at the shield electrode and to charge the shield electrode with an electric voltage in phase with the electrode voltage of the sensor electrode, and

the voltage applied is smaller than the electrode voltage of the sensor electrode.

11. The electrode arrangement according to claim 1, wherein

at least one coupling electrode is between the sensor electrode and the first shield electrode and couplable with the first shield electrode;

and

the output of the capacitive sensor is switchable by the driver circuit on the coupling electrode in order to bring the coupling electrode and the first shield electrode substantially to the electric potential of the sensor electrode.

12. The electrode arrangement according to claim 11, wherein the driver circuit is adapted to drive the current at the coupling electrode and to charge the coupling electrode with an electric voltage in phase with the electrode voltage of the sensor electrode, the voltage applied being smaller than the electrode voltage of the sensor electrode.

13. The electrode arrangement according to claim 11, wherein the shield electrode and the coupling electrode are capacitively coupled.

14. The electrode arrangement according to claim 9, wherein the output of the capacitive sensor is couplable by means of a multiplexer with the amplifying circuit.

15. The electrode arrangement according to claim 8, wherein the inductive component of the resonance circuit is formed by a gyrator.

16. The electrode arrangement according to claim 15, wherein

the gyrator comprises an operational amplifier fed back by a capacitor, which acts at the input of the capacitive sensor as a virtual inductance and

the virtual inductance, together with the sensor electrode connected at the input of the capacitive sensor and with its load capacitance against ground, constitutes a parallel resonant circuit.

17. The electrode arrangement according to claim 16, wherein the output of the operational amplifier is couplable with the amplifying circuit and at the output of the operational amplifier is provided with an attenuator.

18. In combination with the electrode arrangement of claim 1,

a grounded display device for detecting a position or an approach of an object to the display device, the electrode arrangement being in the display device in such a way that the second side of the substrate is directed toward the display device, and the first shield electrode serves to shield the alternating electric field emitted by the sensor electrode from the grounded display device.

19. The electrode configuration according to claim 18, wherein the first shield electrode is DC-couplable or capacitively couplable with a conductive and generally transparent layer situated in front of the display device.

20. The electrode configuration according to claim 19, wherein the first shield electrode is formed by a conductive and generally transparent layer situated in front of the display device.

21. An apparatus comprising the combination according to claim 18 wherein the first shield electrode is embedded in a transparent protective material in the display device, and the first shield electrode serves to shield the electrode field of the sensor electrode from the grounded display device.

22. The apparatus according to claim 21, wherein the first shield electrode and the at sensor electrode each are embedded in a substrate and wherein the substrate is arranged at the surface opposite the display device of the transparent protective material.

23. The apparatus according to claim 22, wherein the substrate is transparent.

24. The apparatus according to claim 21, wherein the display device is a touch-sensitive screen and the first shield electrode or the sensor electrode is formed by the conductive layers of the touch-sensitive screen, the conductive layers of the touch-sensitive screen being coupled with an evaluation unit for contact detection and with an evaluation unit for approximation detection.

25. The apparatus according to claim 24, wherein the apparatus is adapted to evaluate, above a predetermined first spacing of the object from the display device a movement of the object relative to the display device.

26. The apparatus according to claim 25, wherein the evaluation unit for approximation detection is deactivatable when the spacing of the object from the display device is smaller than the first spacing.

27. The apparatus according to claim 26, wherein the apparatus is adapted to evaluate, below a predetermined second spacing of the object from the display device contact of the display device with the object.

28. The apparatus according to claim 27, wherein the second spacing is greater than the first spacing.

29. The apparatus according to claim 24, wherein the conductive layers of the touch-sensitive screen are coupled by time division with the evaluation unit for contact detection and with the evaluation unit for approximation detection.

30. The apparatus according to claim 24, wherein the first shield electrode comprises the coupling electrode.

31. A foil comprising

at least one coupling electrode having a face;

a plurality of sensor electrodes on the face of the coupling electrode and in a predetermined spacing from the coupling electrode, the foil having connectors for connecting the sensor electrodes to an evaluation unit and for connecting the sensor electrodes and the coupling electrode to a driver circuit for the production of a substantially field-free space between the sensor electrodes and the coupling electrode.

32. A method for making an approach-sensitive display device with a touch-sensitive screen comprising conductive structures for detecting a contact, comprising the steps of:

applying a foil according to claim 31 on the touch-sensitive screen with the coupling electrode directed toward the screen and the coupling electrode into a capacitive coupling with the conductive structures of the touch-sensitive screen.

33. The method according to claim 32, further comprising the step of

coupling the foil connections and the conductive structures of the touch-sensitive screen with an evaluation unit for approximation detection, the conductive structures being coupled by time division with the evaluation unit for approximation detection and with an evaluation unit for contact detection.