TOUCH-DETECTION SYSTEM FOR DISPLAY

• US 20110267302A1
• Filed: 01/21/2010
• Published: 11/03/2011
• Est. Priority Date: 01/21/2009
• Status: Active Grant

• Current Assignee: Microchip Technology Germany GmbH (Microchip Technology Incorporated)
• Original Assignee: Microchip Technology Germany GmbH (Microchip Technology Incorporated)
• Inventors: Fasshauer, Peter
• Granted Patent: US 8,823,676 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/044 by capacitive means
• 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
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 17/975 using a capacitive movable element

Abstract

A display screen is carried on a base by an elastically deformable support such that a touch shifts the screen relative to the base. A pair of juxtaposed electrodes form a capacitor, with one of the electrodes fixed to the screen and the other of the electrodes fixed to or formed by the base. A capacitance of the capacitor changes when the screen electrode moves relative to the base electrode. A circuit connected to the electrodes initiates an action on change of the capacitance.

Claims

1. An arrangement for detecting contact on a display, the arrangement comprising:

a screen panel,

an electrode forming part of a capacitor, and

a support carrying the screen panel such that it is moved by a compression force exerted by contact with the screen panel, the electrode being coupled with the screen panel, the capacitor having a capacitance that changes when the support is subjected to a load.

2. The arrangement according to claim 1, wherein the screen panel is rectangular and the electrode is in a corner of the screen panel.

3. The arrangement according to claim 2, wherein the electrode is flat.

4. The arrangement according to claim 3, wherein the electrode is a metallic layer.

5. The arrangement according to claim 1 wherein a change of the capacitance of the capacitor is detected on the basis of a phase shift.

6. The arrangement according to claim 1 wherein the electrode constitutes part of an LC network whose inductance is formed by a gyrator circuit.

7. The arrangement according to at least one of claims claims 1 to 5, characterized in that wherein the electrode assembly constitutes part of an LC network whose inductance is formed by a gyrator circuit.

8. In combination:

a base;

a display screen;

an elastically deformable support carrying the screen on the screen, whereby a touch shifts the screen relative to the base;

a pair of juxtaposed electrodes forming a capacitor, one of the electrodes being fixed to the screen and the other of the electrodes being fixed to or formed by the base, a capacitance of the capacitor changing when the screen electrode moves relative to the base electrode; and

circuit means connected to the electrodes for initiating an action on change of the capacitance.

9. The combination defined in claim 8 wherein the screen is polygonal and has corners, the screen electrode being in at least one of the corners.

10. The combination defined in claim 9 wherein the screen electrode extends annularly around an edge of the screen through all the corners, the base electrode being of generally the same shape as the screen electrode.

11. The combination defined in claim 8 wherein the screen electrode is a metallic trace fixed to the screen.

12. The combination defined in claim 8 wherein the circuit means detects a phase shift of the capacitance.