Sensor for capacitive touch pad pointing device

• US 20050270273A1
• Filed: 06/10/2004
• Published: 12/08/2005
• Est. Priority Date: 06/13/2003
• Status: Active Grant

• Current Assignee: Semtech Corporation
• Original Assignee: Semtech Corporation
• Inventors: Marten, Victor
• Granted Patent: US 7,580,030 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• 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

Abstract

The topology and the shape of sensing electrodes (4, 31) on the Capacity Touch Pad Sensor that allow sensing of small targets are disclosed. Sensor construction utilizes common PCB manufacture technique.

Claims

1. A capacitive touch pad comprising first and second layers,

the first layer comprising a non-conductive cover providing galvanic isolation of the second layer,

the second layer comprising a plurality of row-shaped row-sensing electrodes and a row-by-column array of column-sensing electrodes,

each column of column-sensing electrodes interconnected by conductive traces,

the row-sensing electrodes and column-sensing electrodes defining interleaved combs therebetween, each comb comprising at least two fingers.

2. The capacitive touch pad of claim 1 wherein the fingers are no wider than eight mils.

3. The capacitive touch pad of claim 1 wherein the fingers define spaces therebetween, and the spaces are no wider than eight mils.

4. The capacitive touch pad of claim 1 further comprising a third layer, the second layer lying between the first and third layers, the third layer comprising a ground plane.

5. The capacitive touch pad of claim 4 further comprising a fourth layer, the third layer lying between the second and fourth layers, the fourth layer bearing circuitry.

6. The capacitive touch pad of claim 1 wherein in the second layer further comprises annular copper around the electrodes.

7. The capacitive touch pad of claim 6 wherein the annular copper is connected to ground potential.

8. The capacitive touch pad of claim 1 further comprising an isolator/dielectric layer between the first and second layers.

9. The capacitive touch pad of claim 4 further comprising an isolator/dielectric layer between the second and third layers.

10. The capacitive touch pad of claim 5 further comprising an isolator/dielectric layer between the third and fourth layers.