Pseudo Driven Shield

• US 20150002448A1
• Filed: 06/28/2013
• Published: 01/01/2015
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Brunet, Samuel, Collins, Richard Paul, Hristov, Luben Hristov, Myren, Steinar, Pedersen, Trond Jarle, Stavely, Paul
• Granted Patent: US 9,612,677 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• 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 2203/04108 Touchless 2D- 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 without distance measurement in the Z direction
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• 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

In one embodiment, a touch-sensitive device includes a controller, horizontal electrodes, and vertical electrodes. The touch-sensitive device further includes a first plurality of switches that couple the horizontal electrodes to a first plurality of sensors, a second plurality of switches that couple the vertical electrodes to a second plurality of sensors, and a third and fourth plurality of switches that couple the horizontal and vertical electrodes to a shield sensor. The controller is operable to perform simultaneous hovering, touch, and proximity detection by selectively controlling the first, second, third, and fourth plurality of switches. The hovering, touch, and proximity detection includes causing substantially equal voltages to be present on the horizontal and vertical electrodes while measuring capacitances using the shield sensor and either the first or second plurality of sensors.

Claims

1. A touch sensor for a touch-sensitive device comprising:

a controller;

a plurality of horizontal electrodes;

a plurality of vertical electrodes;

a first plurality of switches operable to electrically couple the plurality of horizontal electrodes to a first plurality of sensors;

a second plurality of switches operable to electrically couple the plurality of vertical electrodes to a second plurality of sensors;

a third plurality of switches operable to electrically couple the plurality of horizontal electrodes to a shield sensor; and

a fourth plurality of switches operable to electrically couple the plurality of vertical electrodes to the shield sensor;

wherein the controller is operable to perform simultaneous hovering, touch, and proximity detection by selectively controlling the first, second, third, and fourth plurality of switches, the hovering, touch, and proximity detection comprising causing substantially equal voltages to be present on the plurality of horizontal and vertical electrodes while measuring capacitances using the shield sensor and either the first or second plurality of sensors.

2. The touch sensor of claim 1, wherein the shield sensor comprises a shield current source sensor, and electrodes coupled to the shield current source sensor are charged with current sources that are tuned to produce a similar charging curve as electrodes of the touch sensor that are not coupled to the shield current source sensor.

3. The touch sensor of claim 1, wherein the shield sensor comprises a shield current source sensor, and the plurality of horizontal and vertical electrodes are charged with limited currents that are tuned to produce identical charging.

4. The touch sensor of claim 1, wherein the shield sensor comprises a sampling capacitor that has a value that produces identical voltages on electrodes coupled to the shield sensor as voltages on electrodes of the touch sensor not coupled to the shield sensor.

5. The touch sensor of claim 1, wherein:

controlling the first, second, third, and fourth plurality of switches comprises;

closing the first plurality of switches to couple each of the plurality of horizontal electrodes to a particular one of the first plurality of sensors;

opening the second plurality of switches to decouple the plurality of vertical electrodes from the second plurality of sensors;

opening the third plurality of switches to decouple the plurality of horizontal electrodes from the shield sensor; and

closing the fourth plurality of switches to couple all electrodes of the plurality of vertical electrodes to the shield sensor; and

measuring the capacitances comprises;

measuring, using the first plurality of sensors, capacitances of each individual electrode of the plurality of horizontal electrodes; and

measuring, using the shield sensor, a single capacitance for all of the vertical electrodes.

6. The touch sensor of claim 1, wherein:

controlling the first, second, third, and fourth plurality of switches comprises;

opening the first plurality of switches to decouple the plurality of horizontal electrodes from the first plurality of sensors;

closing the second plurality of switches to couple each of the plurality of vertical electrodes to a particular one of the second plurality of sensors;

closing the third plurality of switches to couple all electrodes of the plurality of horizontal electrodes to the shield sensor; and

opening the fourth plurality of switches to decouple the vertical electrodes from the shield sensor; and

measuring the capacitances comprises;

measuring, using the second plurality of sensors, capacitances of each individual electrode of the plurality of vertical electrodes; and

measuring, using the shield sensor, a single capacitance for all of the horizontal electrodes.

7. The touch sensor of claim 1, wherein:

the first, second, third, and fourth plurality of switches comprise analog switches; and

the first and second plurality of sensors each comprise one of;

a current source sensor;

or

a capacitive sensor.

8. A touch-sensitive device comprising a controller, the controller operable to:

selectively control a first, second, third, and fourth plurality of switches of a touch sensor, wherein;

the first plurality of switches are operable to electrically couple a plurality of first electrodes of the touch sensor to a plurality of sensors;

the second plurality of switches are operable to electrically couple a plurality of second electrodes of the touch sensor to the plurality of sensors;

the third plurality of switches are operable to electrically couple the plurality of first electrodes to a shield sensor; and

the fourth plurality of switches are operable to electrically couple the plurality of second electrodes to the shield sensor;

cause substantially equal voltages to be present on the plurality of first and second electrodes; and

measure, while the plurality of first and second electrodes are at substantially equal voltages, capacitances using the plurality of sensors.

9. The touch-sensitive device of claim 8, wherein the shield sensor comprises a shield current source sensor, and electrodes coupled to the shield current source sensor are charged with current sources that are tuned to produce a similar charging curve as electrodes of the touch sensor that are not coupled to the shield current source sensor.

10. The touch-sensitive device of claim 8, wherein the shield sensor comprises a shield current source sensor, and the plurality of first and second electrodes are charged with limited currents that are tuned to produce identical charging.

11. The touch-sensitive device of claim 8, wherein the shield sensor comprises a sampling capacitor that has a value that produces identical voltages on electrodes coupled to the shield sensor as voltages on electrodes of the touch sensor not coupled to the shield sensor.

12. The touch-sensitive device of claim 8, wherein:

controlling the first, second, third, and fourth plurality of switches comprises;

closing the first plurality of switches to couple each of the plurality of first electrodes to a particular one of the plurality of sensors;

opening the second plurality of switches to decouple the plurality of second electrodes from the plurality of sensors;

opening the third plurality of switches to decouple the plurality of first electrodes from the shield sensor; and

closing the fourth plurality of switches to couple all electrodes of the plurality of second electrodes to the shield sensor; and

measuring the capacitances comprises one or more of;

measuring, using the plurality of sensors, capacitances of each individual electrode of the plurality of first electrodes; and

measuring, using the shield sensor, a single capacitance for all of the second electrodes.

13. The touch-sensitive device of claim 8, the controller further operable to select two or more first electrodes of the plurality of first electrodes as a group of electrodes to measure, wherein:

first electrodes of the plurality of first electrodes not selected to be in the selected group of electrodes comprise a non-selected group of electrodes;

controlling the first, second, third, and fourth plurality of switches comprises;

closing switches of the first plurality of switches that are associated with the selected group of electrodes in order to couple each of the selected group of electrodes to one of the plurality of sensors;

opening switches of the first plurality of switches that are associated with the non-selected group of electrodes in order to decouple the non-selected group of electrodes from the plurality of sensors;

opening switches of the third plurality of switches that are associated with the selected group of electrodes in order to decouple the selected group of electrodes from the shield sensor;

closing switches of the third plurality of switches that are associated with the non-selected group of electrodes in order to couple the non-selected group of electrodes to the shield sensor;

opening the second plurality of switches to decouple the plurality of second electrodes from the plurality of sensors;

closing the fourth plurality of switches to couple the second electrodes to the shield sensor; and

measuring the capacitances comprises one or more of;

measuring, using the plurality of sensors, capacitances of each individual electrode of the selected group of electrodes; and

measuring, using the shield sensor, a single capacitance for all second electrodes and electrodes in the non-selected group of electrodes.

14. The touch-sensitive device of claim 8, wherein:

the plurality of first electrodes comprise horizontal electrodes; and

the plurality of second electrodes comprise vertical electrodes.

15. A method comprising:

selectively controlling a first, second, third, and fourth plurality of switches of a touch sensor, wherein;

the first plurality of switches are operable to electrically couple a plurality of horizontal electrodes of the touch sensor to a first plurality of sensors;

the second plurality of switches are operable to electrically couple a plurality of vertical electrodes of the touch sensor to a second plurality of sensors;

the third plurality of switches are operable to electrically couple the plurality of horizontal electrodes to a shield sensor; and

the fourth plurality of switches are operable to electrically couple the plurality of vertical electrodes to the shield sensor;

causing substantially equal voltages to be present on the plurality of horizontal and vertical electrodes; and

measuring, while the plurality of horizontal and vertical electrodes are at substantially equal voltages, capacitances using at least a portion of either the first or second plurality of sensors.

16. The method of claim 15, wherein the shield sensor comprises a shield current source sensor, and electrodes coupled to the shield current source sensor are charged with current sources that are tuned to produce a similar charging curve as electrodes of the touch sensor that are not coupled to the shield current source sensor.

17. The method of claim 15, wherein the shield sensor comprises a shield current source sensor, and the plurality of horizontal and vertical electrodes are charged with limited currents that are tuned to produce identical charging.

18. The method of claim 15, wherein the shield sensor comprises a sampling capacitor that has a value that produces identical voltages on electrodes coupled to the shield sensor as voltages on electrodes of the touch sensor not coupled to the shield sensor.

19. The method of claim 15, wherein:

controlling the first, second, third, and fourth plurality of switches comprises;

closing the first plurality of switches to couple each of the plurality of horizontal electrodes to a particular one of the first plurality of sensors;

opening the second plurality of switches to decouple the plurality of vertical electrodes from the second plurality of sensors;

opening the third plurality of switches to decouple the plurality of horizontal electrodes from the shield sensor; and

closing the fourth plurality of switches to couple all electrodes of the plurality of vertical electrodes to the shield sensor; and

measuring the capacitances comprises one or more of;

measuring, using the first plurality of sensors, capacitances of each individual electrode of the plurality of horizontal electrodes; and

measuring, using the shield sensor, a single capacitance for all of the vertical electrodes.

20. The method of claim 15, wherein:

controlling the first, second, third, and fourth plurality of switches comprises;

opening the first plurality of switches to decouple the plurality of horizontal electrodes from the first plurality of sensors;

closing the second plurality of switches to couple each of the plurality of vertical electrodes to a particular one of the second plurality of sensors;

closing the third plurality of switches to couple all electrodes of the plurality of horizontal electrodes to the shield sensor; and

opening the fourth plurality of switches to decouple the vertical electrodes from the shield sensor; and

measuring the capacitances comprises one or more of;

measuring, using the second plurality of sensors, capacitances of each individual electrode of the plurality of vertical electrodes; and

measuring, using the shield sensor, a single capacitance for all of the horizontal electrodes.