Touch Sensitive Screen

• US 20070062739A1
• Filed: 09/18/2006
• Published: 03/22/2007
• Est. Priority Date: 09/20/2005
• Status: Active Grant

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Philipp, Harald, Brunet, Samuel
• Granted Patent: US 7,932,898 B2
• Time in Patent Office: Days
• US Class Current: 178/18.60
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes

Abstract

A capacitive sensor for determining the presence of an object, such as a user'"'"'s finger or a stylus, is provided. The sensor comprises a substrate, for example made of transparent plastics material, such as PET, on which electrodes are deposited. A resistive drive electrode for example formed of transparent ITO, is arranged on one side of the substrate and a resistive sense electrode, which again may be of transparent ITO, is arranged on the other side of the substrate. Thus an overall transparent sensor may be provided. A shorting connection is also provided which is configured to connect between two locations on one of the electrodes. The electrodes are connected to respective drive and sense channels. By providing the shorting connection between two locations on one or other (or both) of the electrodes, a lower resistance connection is provided between other locations on the electrode and the corresponding drive or sense channel.

Claims

1. A capacitive sensor comprising:

a substrate;

a resistive first electrode on one side of the substrate;

a resistive second electrode on the other side of the substrate; and

a shorting connection configured to connect between at least two locations on the first electrode.

2. The sensor of claim 1 comprising a further shorting connection configured to connect between at least two locations on the second electrode.

3. The sensor of claim 1, wherein one of the first and second electrodes is arranged in a pattern having an array of open regions and the other of the first and second electrodes is arranged in a pattern having an array of filled regions configured to align with the open regions.

4. The sensor of claim 3, further comprising areas formed from the same material as the electrodes disposed within the open regions and electrically isolated from the electrodes.

5. The sensor of claim 1, wherein the electrodes are transparent.

6. The sensor of claim 5, wherein the substrate is transparent.

7. The sensor of claim 1 comprising at least one further electrode on the same side of the substrate as the first electrode.

8. The sensor of claim 7 comprising a ground electrode disposed between the first electrode and the at least one further electrode.

9. The sensor of claim 1 comprising at least one further electrode on the same side of the substrate as the second electrode.

10. The sensor of claim 9 comprising a ground electrode disposed between the second electrode and the at least one further electrode.

11. The sensor of claim 1 comprising at least one further electrode on same side of the substrate as the first electrode and at least one further electrode on the same side of the substrate as the second electrode.

12. The sensor of claim 11 wherein the electrodes are arranged in a matrix array.

13. The sensor of claim 1 comprising a drive channel operable to apply electrical drive signals to one of the first or second electrodes and a sense channel operable to detect electrical sense signals induced in the other of the first or second electrodes in response to the drive signal.

14. The sensor of claim 13, wherein the drive channel comprises a switch element operable to selectively connect and disconnect its associated electrode to a voltage source.

15. The sensor of claim 13, wherein the sense channel comprises a charge transfer circuit.

16. The sensor of claim 14, wherein the sense channel is associated with the electrode on the side of the substrate that faces an object to be sensed during normal use.

17. A control panel comprising the sensor of claim 1 and a cover panel overlying the sensor.

18. The control panel of claim 17, wherein the cover panel and the sensor are attached to one another by a refractive index matching adhesive.

19. The control panel of claim 17, further comprising a display screen underlying the sensor.

20. The control panel of claim 19, wherein the display screen and the sensor are attached to one another by a refractive index matching adhesive.

21. An apparatus comprising the control panel of claim 17.