Capacitive sensing control knob

• US 20090009491A1
• Filed: 01/02/2008
• Published: 01/08/2009
• Est. Priority Date: 07/04/2007
• Status: Active Grant

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Grivna, Edward L.
• Granted Patent: US 8,766,910 B2
• Time in Patent Office: Days
• US Class Current: 345/184
• CPC Class Codes: G06F 3/033 Pointing devices displaced or positioned by the user , e.g. mice, trackballs, pens or joysticks; Accessories therefor digitisers characterised by the transducing means G06F3/041
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 17/98 having a plurality of control members, e.g. keyboard
• CPC Class Codes: H03K 2217/94073 with capacitive detection
• CPC Class Codes: H03K 2217/960725 Charge-transfer

Abstract

Apparatuses and methods for detecting interaction of a user with a sensor array disposed on the wall of a protrusion from the surface of a control panel of a device that physically resembles a mechanical knob protruding from the surface of the control panel of the device. The method may include receiving a plurality of signals from the sensor array and detecting interaction of a user with the sensor array based on the plurality of signals.

Claims

1. A method, comprising:

receiving a plurality of signals from a sensor array disposed on the wall of a protrusion from the surface of a control panel of a device that physically resembles a mechanical knob protruding from the surface of the control panel of the device; and

detecting interaction of a user with the sensor array based on the plurality of signals.

2. The method of claim 1, wherein detecting the interaction comprises:

determining a presence of a conductive object on the sensor array;

determining a direction of the conductive object on the sensor array; and

determining a change in position of the conductive object on the sensor array.

3. The method of claim 2, wherein detecting the interaction further comprises:

detecting presences of multiple conductive objects on the sensor array;

determining positions of the multiple conductive objects; and

identifying one of the multiple conductive objects as a reference indicator based on the positions of the multiple conductive objects, wherein said detecting the interaction comprises determining a direction of movement of the reference indicator and a change in position of the reference indicator.

4. The method of claim 3, wherein determining the positions comprises determining a capacitance maximum for each of the multiple conductive objects, wherein each capacitance maximum corresponds to the positions of the multiple conductive objects, and wherein identifying one of the multiple conductive objects as the reference indicator comprises:

determining a distance between each adjacent position of the multiple conductive objects based on the capacitance maxima; and

identify a reference position using the greatest distance between the adjacent positions of the multiple conductive objects, wherein the conductive object that is located at the reference position is identified as the reference indicator.

5. An apparatus, comprising:

a control panel having a protrusion from the surface of the control panel that physically resembles a mechanical knob protruding from the surface of the control panel, wherein the protrusion is cylindrical or conical; and

a sensor array disposed on the wall of the protrusion.

6. The apparatus of claim 5, further comprising a processing device coupled to the sensor array to detect interaction of a user with the sensor array.

7. The apparatus of claim 6, further comprising a display disposed on the top surface of the protrusion to indicate the user interaction with the control panel.

8. The apparatus of claim 6, further comprising an external indicator to indicate the user interaction with the control panel.

9. The apparatus of claim 5, wherein the apparatus is an electrical appliance, and wherein the processing device, protrusion, and sensor array operate as a control knob of the electrical appliance.

10. The apparatus of claim 5, further comprising a passive moveable part disposed on the protrusion to allow a user to grip the surface of the moveable part and physically move the moveable part, while the sensor array and protrusion remain in fixed, non-moveable locations.

11. The apparatus of claim 5, wherein the bottom perimeter of the outer wall of the protrusion is sealed against the control panel and a top surface of the protrusion is sealed against the walls of the protrusion, and wherein the sealed protrusion is configured to prevent contamination of circuitry located on the back side of the control panel and to protect the circuitry from electrostatic discharge events.

12. The apparatus of claim 5, wherein the protrusion and the control panel are one integrated piece, and wherein the protrusion includes an opening on the back side of the protrusion that allows access to the wall of the protrusion.

13. An apparatus, comprising

a processing device to receive a plurality of signals from a sensor array disposed on the wall of a protrusion from the surface of a control panel of a device, wherein the processing device is configured to detect interaction of a user with the sensor array.

14. The apparatus of claim 13, wherein the processing device is configured to detect at least one of a direction, a position, or a change in position of a conductive object with respect to the sensor array as part of the interaction of the user with the sensor array.

15. The apparatus of claim 13, wherein the processing device is configured to detect the positions of multiple fingers of the user as part of the interaction of the user with the sensor array.

16. The apparatus of claim 15, wherein the processing device is further configured to detect a position of a thumb when multiple fingers of the user are detected, and wherein the processing device is further configured to detect at least one of a direction, a position, or a change in position of the thumb.

17. The apparatus of claim 13, wherein the processing device is configured to detect a position of a single finger of the user as part of the interaction of the user with the sensor array.

18. The apparatus of claim 13, wherein the processing device comprises:

a capacitance sensor to measure a capacitance on the sensor array; and

a selection circuit coupled to a plurality of sensor elements of the sensor array and the capacitance sensor, wherein the selection circuit is configured to select each of the plurality of sensor elements to measure the capacitance on each of the plurality of sensor elements.

19. The apparatus of claim 18, wherein the capacitance sensor is a relaxation oscillator, and wherein the relaxation oscillator is coupled to a digital counter.

20. The apparatus of claim 18, wherein the capacitance sensor includes a sigma-delta modulator circuit, and wherein the sigma-delta modulator circuit is coupled to a digital filter to measure a ratio of pulse widths of an output of the sigma-delta modulator circuit.