Capacitive and inductive sensing

• US 9,160,331 B2
• Filed: 01/20/2012
• Issued: 10/13/2015
• Est. Priority Date: 10/28/2011
• Status: Active Grant

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Bakken, Vemund Kval, Ali, Yassar, Pedersen, Trond Jarle
• Primary Examiner(s): Wang, Quan-Zhen
• Assistant Examiner(s): DICKE, CHAD M
• Application Number:
  US13/355,013
• Publication Number:
  US 20130106769A1
• Time in Patent Office: 1,362 Days
• US Class Current: 1/1
• 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
• CPC Class Codes: G06F 3/046 by electromagnetic means
• CPC Class Codes: H03K 17/9505 Constructional details
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 2217/960775 Emitter-receiver or "fringe" type detection, i.e. one or more field emitting electrodes and corresponding one or more receiving electrodes

Abstract

In one embodiment, a method includes in an inductive-sensing mode, by a controller, applying an alternating-current (AC) signal on a first electrode of a capacitive touch sensor. The capacitive touch sensor is configured to operate in the inductive-sensing mode and a capacitive-sensing mode. The method also includes sensing a signal indicative of a magnetic field on the first electrode. The signal is due at least in part to a magnetic field generated by the object and the magnetic field is generated at least in part in response to the AC signal applied on the first electrode. The method also includes determining a position of the object generating the magnetic field based on the signal indicative of the magnetic field.

Claims

1. A method comprising:

in an inductive-sensing mode, by a controller, applying a first alternating-current (AC) signal on a first electrode of a capacitive touch sensor, the capacitive touch sensor configured to operate in the inductive-sensing mode and a capacitive-sensing mode, the first electrode configured, in the capacitive-sensing mode, to operate as a drive electrode, the first electrode coupled, in the inductive sensing mode, to the first AC signal by a first pair of switches;

sensing, on the first electrode, a first signal indicative of a first magnetic field, the first signal due at least in part to a first magnetic field generated by an object, the first magnetic field generated by the object being generated at least in part in response to the first AC signal applied on the first electrode, the first electrode coupled, in the inductive sensing mode, to a first sensor by a second pair of switches, the second pair of switches different than the first pair of switches;

in the inductive-sensing mode, by the controller, applying a second AC signal on a second electrode of the capacitive touch sensor, the second electrode configured, in the capacitive-sensing mode, to operate as a sense electrode, the second electrode coupled, in the inductive sensing mode, to the second AC signal by a third pair of switches, the third pair of switches different than the first and second pairs of switches;

sensing, on the second electrode, a second signal indicative of a second magnetic field, the second signal due at least in part to a second magnetic field generated by the object, the second magnetic field generated by the object being generated at least in part in response to the second AC signal applied on the second electrode, the second electrode coupled, in the inductive sensing mode, to a second sensor by a fourth pair of switches, the fourth pair of switches different than the first, second, and third pairs of switches, the second sensor being one of the first sensor and a sensor different than the first sensor; and

determining a position of the object generating the first magnetic field and the second magnetic field based on the first signal indicative of the first magnetic field and the second signal indicative of the second magnetic field.

2. The method of claim 1, wherein the object generating the first magnetic field and the second magnetic field is a stylus with an inductor.

3. The method of claim 1, further comprising:

in the capacitive-sensing mode, applying a voltage to the first electrode;

sensing, by the second electrode, a signal indicative of a change in an electric field, the signal due at least in part to an electric field generated at least in part by the voltage applied on the first electrode; and

determining a position of an object with high permittivity based on the signal indicative of the change in the electric field.

4. The method of claim 3, further comprising:

time multiplexing between the inductive-sensing mode and the capacitive-sensing mode; and

isolating an input from the object generating the magnetic field through the time multiplexing between the inductive-sensing mode and the capacitive-sensing mode.

5. The method of claim 1, further comprising receiving data from the object encoded through modulation of one or more of the generated first magnetic field and the generated second magnetic field.

6. The method of claim 1, wherein the first electrode and the second electrode are formed from conductive material disposed along a periphery of an electrode shape.

7. The method of claim 1, further comprising:

coupling the first electrode to a drive unit of the controller for a pre-determined amount of time;

decoupling the first electrode from the drive unit after the pre-determined amount of time; and

coupling the first electrode to a sense unit of the controller for detecting sensing a signal indicative of the magnetic field.

8. A computer-readable non-transitory storage medium embodying logic configured when executed to perform operations comprising:

in an inductive-sensing mode, applying a first alternating-current (AC) signal on a first electrode of a capacitive touch sensor, the capacitive touch sensor configured to operate in the inductive-sensing mode and a capacitive-sensing mode, the first electrode configured, in the capacitive-sensing mode, to operate as a drive electrode, the first electrode coupled, in the inductive sensing mode, to the first AC signal by a first pair of switches;

sensing, on the first electrode, a first signal indicative of a first magnetic field, the first signal due at least in part to a first magnetic field generated by an object, the first magnetic field generated by the object being generated at least in part in response to the first AC signal applied on the first electrode, the first electrode coupled, in the inductive sensing mode, to a first sensor by a second pair of switches, the second pair of switches different than the first pair of switches;

in the inductive-sensing mode, by the controller, applying a second AC signal on a second electrode of the capacitive touch sensor, the second electrode configured, in the capacitive-sensing mode, to operate as a sense electrode, the second electrode coupled, in the inductive sensing mode, to the second AC signal by a third pair of switches, the third pair of switches different than the first and second pairs of switches;

sensing, on the second electrode, a second signal indicative of a second magnetic field, the second signal due at least in part to a second magnetic field generated by the object, the second magnetic field generated by the object being generated at least in part in response to the second AC signal applied on the second electrode, the second electrode coupled, in the inductive sensing mode, to a second sensor by a fourth pair of switches, the fourth pair of switches different than the first, second, and third pairs of switches, the second sensor being one of the first sensor and a sensor different than the first sensor; and

determining a position of the object generating the first magnetic field and the second magnetic field based on the first signal indicative of the first magnetic field and the second signal indicative of the second magnetic field.

9. The medium of claim 8, wherein the object generating the first magnetic field and the second magnetic field is a stylus with an inductor.

10. The medium of claim 8, wherein the logic is further configured to perform operations comprising:

in a capacitive-sensing mode, applying a voltage to the first electrode;

sensing, by the second electrode, a signal indicative of an electric field, the signal due at least in part to the electric field generated at least in part by the voltage applied on the first electrode; and

determining a presence of an object with high permittivity based on the signal indicative of the electric field.

11. The medium of claim 10, wherein the logic is further configured to perform operations comprising:

time multiplexing between the inductive-sensing mode and the capacitive-sensing mode; and

isolating an input from the object generating the magnetic field through the time multiplexing between the inductive-sensing mode and the capacitive-sensing mode.

12. The medium of claim 8, wherein the logic is further configured to perform operations comprising receiving data from the object encoded through modulation of one or more of the generated first magnetic field and the generated second magnetic field.

13. The medium of claim 8, wherein the first electrode and the second electrode are formed from conductive material disposed along a periphery of an electrode shape.

14. The medium of claim 8, wherein the logic is further configured to perform operations comprising:

coupling the first electrode to a drive unit of the controller for a pre-determined amount of time;

decoupling the first electrode from the drive unit after the pre-determined amount of time; and

coupling the first electrode to a sense unit of the controller for detecting sensing a signal indicative of the magnetic field.

15. A device comprising:

a capacitive touch sensor comprising a first electrode and a second electrode, the capacitive touch sensor configured to operate in the inductive-sensing mode and a capacitive-sensing mode; and

a computer-readable non-transitory storage medium coupled to the capacitive touch sensor and embodying logic configured when executed to perform operations comprising;

in the inductive-sensing mode, applying a first an alternating-current (AC) signal on the first electrode, the first electrode configured, in the capacitive-sensing mode, to operate as a drive electrode, the first electrode coupled, in the inductive sensing mode, to the first AC signal by a first pair of switches;

sensing, on the first electrode, a first signal indicative of a first magnetic field, the first signal due at least in part to a first magnetic field generated by an object, the first magnetic field generated by the object being generated at least in part in response to the first AC signal applied on the first electrode, the first electrode coupled, in the inductive sensing mode, to a first sensor by a second pair of switches, the second pair of switches different than the first pair of switches;

in the inductive-sensing mode, by the controller, applying a second AC signal on a second electrode of the capacitive touch sensor, the second electrode configured, in the capacitive-sensing mode, to operate as a sense electrode, the second electrode coupled, in the inductive sensing mode, to the second AC signal by a third pair of switches, the third pair of switches different than the first and second pairs of switches;

sensing, on the second electrode, a second signal indicative of a second magnetic field, the second signal due at least in part to a second magnetic field generated by the object, the second magnetic field generated by the object being generated at least in part in response to the second AC signal applied on the second electrode, the second electrode coupled, in the inductive sensing mode, to a second sensor by a fourth pair of switches, the fourth pair of switches different than the first, second, and third pairs of switches, the second sensor being one of the first sensor and a sensor different than the first sensor; and

determining a position of the object generating the first magnetic field and the second magnetic field based on the first signal indicative of the first magnetic field and the second signal indicative of the second magnetic field.

16. The device of claim 15, wherein the object generating the first magnetic field and the second magnetic field is a stylus with an inductor.

17. The device of claim 15, wherein the logic is further configured to perform operations comprising:

in the capacitive-sensing mode, applying a voltage to the first electrode;

sensing, by the second electrode, a signal indicative of an electric field, the signal due at least in part to an electric field generated at least in part by the voltage applied on the first electrode; and

determining a presence of an object with high permittivity based on the signal indicative of the electric field.

18. The device of claim 17, wherein the logic is further configured to perform operations comprising:

time multiplexing between the inductive-sensing mode and the capacitive-sensing mode; and

isolating an input from the object generating the magnetic field through the time multiplexing between the inductive-sensing mode and the capacitive-sensing mode.

19. The device of claim 15, wherein the first electrode and the second electrode are formed from conductive material disposed along a periphery of an electrode shape.

20. The device of claim 15, wherein the logic is further configured to perform operations comprising:

coupling the first electrode to a drive unit of the controller for a pre-determined amount of time;

decoupling the first electrode from the drive unit after the pre-determined amount of time; and

coupling the first electrode to a sense unit of the controller for detecting sensing a signal indicative of the magnetic field.