CAPACITIVE TOUCH PAD CONFIGURED FOR PROXIMITY DETECTION

• US 20140192021A1
• Filed: 03/11/2014
• Published: 07/10/2014
• Est. Priority Date: 12/01/2010
• Status: Active Grant

• Current Assignee: STMicroelectronics SAS (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SAS (STMicroelectronics NV)
• Inventors: Beyly, Laurent, Troise, Cyril, Teissier, Maxime
• Granted Patent: US 9,019,236 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04101 2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• 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: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2217/960725 Charge-transfer

Abstract

The present disclosure relates to a method for controlling a touch pad, comprising an object locate mode for locating an object on the touch pad comprising steps of: determining a measurement of capacitance of each of the pairs of electrodes of the touch pad, each pair comprising a row electrode and a column electrode transverse to the row electrode, comparing each measurement with a first detection threshold, and if the comparison of at least one measurement with the first threshold reveals the presence of an object on the touch pad, locating the object on the touch pad according to the capacitance measurements, the method comprising a proximity detection mode comprising steps of: determining a measurement representative of the capacitance between one or two electrodes and one or two other electrodes of the touch pad, and comparing a measurement obtained with a second detection threshold different from the first threshold.

Claims

1. A device, comprising:

a touch pad, having a plurality of row electrodes that each extend from a top side to a bottom side of the touch pad and a plurality of column electrodes that are transverse to the row electrodes, the plurality of column electrodes each extend from a left side to a right side of the touch pad;

an object detection circuit operable in an object locate mode and a proximity detection mode, wherein;

in the object locate mode, the object detection circuit;

activates a first pair of electrodes, a first one of the first pair being one of the row electrodes and a second one of the first pair being one of the column electrodes;

determines a first capacitance between the first pair of electrodes to determine a location of an object on the touch pad;

in the proximity detection mode, the object detection circuit;

activates a second pair of electrodes, a first one of the second pair being one of the row electrodes and a second one of the second pair being a different one of the row electrodes, the different one of the row electrodes being spaced from the one of the row electrodes by at least one other row electrode; and

determines a second capacitance between the second pair of electrodes to determine if an object is within a proximity of the touch pad.

2. The device of claim 1 wherein each row electrode is an elongated rectangular electrode and wherein each column electrode is an elongated rectangular electrode.

3. The device of claim 1 wherein in the object locate mode the first one of the first pair is a sending electrode and the second one of the first pair is a receiving electrode and the first one of the second pair is a sending electrode and the second one of the second pair is a receiving electrode.

4. The device of claim 1 wherein the object detection circuit includes:

a plurality of row ports, each row port being coupled to one row electrode;

a plurality of column ports, each column port being coupled to one column electrode; and

a sampling capacitor coupled to between the plurality of row ports and between the plurality of column ports.

5. The device of claim 1 wherein each one of the plurality of row electrodes overlaps each one of the plurality of column electrodes.

6. A device, comprising:

a touch detection panel, the panel including;

a first plurality of elongated electrodes; and

a second plurality of elongated electrodes transverse to the first plurality of electrodes;

control circuitry coupled to the first and second pluralities of electrodes, the control circuitry including;

a first set of ports coupled to the first plurality of electrodes;

a second set of ports coupled to the second plurality of electrodes; and

a first sampling capacitor having a first terminal coupled to each of the first set of ports and a second terminal coupled to each of the second set of ports.

7. The device of claim 6 wherein the first plurality of electrodes are substantially parallel to each other and the second plurality of electrodes are substantially parallel to each other.

8. The device of claim 6 wherein the control circuitry includes a comparator that is coupled to the second terminal of the first sampling capacitor, the comparator being configured to compare an output of the first sampling capacitor with a first threshold that corresponds to a presence of an object on a surface the device.

9. The device of claim 8 wherein the control circuitry includes:

a logic block coupled to the comparator; and

a switching block coupled to the first set of ports and the second set of ports, the logic block coupled to and configured to control the switching block based on a detection signal from the comparator.

10. The device of claim 8 wherein the comparator is configured to compare the first sampling capacitor with a second threshold that corresponds to a presence of the object within distance of the surface of the device.

11. The device of claim 6 wherein each one of the first plurality electrodes overlaps each one of the second plurality of electrodes.

12. A method, comprising:

controlling a first plurality of elongated electrodes and a second plurality of elongated electrodes, the first plurality of electrodes being transverse to the second plurality of electrodes such that each one of the first plurality of electrodes overlaps each one of the second plurality of electrodes, the controlling including;

performing an object location routine, the performing of the object location mode including;

activating a first one of the first plurality of electrodes and a second one of the second plurality of electrodes;

determining a first capacitance between the first one of the first plurality of electrodes and the second one of the second plurality of electrodes;

comparing the first capacitance with a first detection threshold; and

performing a proximity detection routine, the performing of the proximity detection mode including;

activating the first one of the first plurality of electrodes and a second one of the first plurality of electrodes, the first one being separated from the second one by at least one of the first plurality of electrodes;

determining a second capacitance between the first one of the first plurality of electrodes and the second one of the first plurality of electrodes;

comparing the second capacitance with a second detection threshold.

13. The method of claim 12 wherein performing the object location routine includes determining if an object is between a surface of a touch panel device housing the first and second pluralities of electrodes and a first distance from the surface and performing the proximity detection routine includes determining if the object is between the first distance and a second distance from the surface.

14. The method of claim 12 wherein the performing the object location routine and performing the proximity detection routine includes:

controlling a first set of ports coupled to the first plurality of electrodes;

controlling a second set of ports coupled to the second plurality of electrodes; and

detecting the first capacitance and the second capacitance from a sampling capacitor having a first terminal coupled to each of the first set of ports and a second terminal coupled to each of the second set of ports.

15. The method of claim 12 wherein the second detection threshold is larger than the first detection threshold.