Capacitive position encoder

• US 9,035,663 B2
• Filed: 09/11/2012
• Issued: 05/19/2015
• Est. Priority Date: 09/11/2012
• Status: Expired due to Fees

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: CARLEY, Carl
• Primary Examiner(s): LEDYNH, BOT L
• Application Number:
  US13/610,114
• Publication Number:
  US 20140070797A1
• Time in Patent Office: 980 Days
• Field of Search: 324/658
• US Class Current: 324/658
• CPC Class Codes: G01D 5/2415 adapted for encoders

Abstract

In one embodiment, a method comprises driving one or more drive electrodes formed on a substrate with one or more drive signals. A wiper comprising at least one arm is driven to a predetermined voltage. The wiper is electrically insulated from a plurality of sense electrodes formed on the substrate. For each sense electrode of the plurality of sense electrodes, a charge stored by the sense electrode is detected. A processor determines a position of the wiper based on the detected charges stored by the plurality of sense electrodes.

Claims

1. A device comprising:

a substrate;

a drive electrode disposed on a first side of the substrate;

a plurality of sense electrodes disposed on a second side of the substrate;

a wiper comprising at least one arm, the wiper electrically insulated from the plurality of sense electrodes, the wiper coupled to a ground of the device; and

a controller coupled to the drive electrode and the plurality of sense electrodes, the controller comprising;

a drive unit configured to generate at least one drive signal and drive the drive electrode with the at least one drive signal;

a sense unit configured to detect, for each sense electrode of the plurality of sense electrodes, a charge stored by the sense electrode; and

a processor unit operable to determine a position of the wiper relative to the plurality of sense electrodes, the determination based on the plurality of charges detected by the sense unit.

2. The device of claim 1, wherein the wiper further comprises a rotary shaft coupled to the at least one arm of the wiper.

3. The device of claim 1, wherein the wiper comprises a plurality of arms that extend in a radial direction from a rotary shaft of the wiper.

4. The device of claim 1, wherein at least one radial angle formed between a first pair of adjacent arms of the wiper is different from at least one other radial angle formed between a second pair of adjacent arms of the wiper.

5. The device of claim 1, the drive electrode having an annular shape.

6. The device of claim 1, wherein the wiper further comprises a shaft that extends in a first direction and each of the at least one arm of the wiper extends in a second direction from the shaft, the first direction being perpendicular to the second direction.

7. The device of claim 1, wherein the wiper is configured to change position relative to the plurality of sense electrodes in response to a user action.

8. A method comprising:

driving one or more drive electrodes former on a substrate with one or more drive signals;

driving a wiper comprising at least one arm to a predetermined voltage, the wiper electrically insulated from a plurality of sense electrodes formed on the substrate;

detecting, for each sense electrode of the plurality of sense electrodes, a charge stored by the sense electrode; and

determining, by a processor, a position of the wiper based on the detected charges stored by the plurality of sense electrodes.

9. The method of claim 8, further comprising changing the position of the wiper in response to a user action.

10. The method of claim 8, wherein the one or more drive electrodes are formed on a first side of the substrate and the plurality of sense electrodes are formed on a second side of the substrate.

11. The method of claim 8, wherein the wiper further comprises a rotary shaft coupled to the at least one arm.

12. The method of claim 8, wherein the wiper comprises a plurality of arms that extend in a radial direction.

13. The method of claim 8, wherein at least one radial angle formed between a first pair of adjacent arms of the wiper is different from at least one other radial angle formed between a second pair of adjacent arms of the wiper.

14. The method of claim 8, wherein the at least one arm of the wiper extends in a first direction from a shaft of the wiper that extends in a second direction, the first direction being perpendicular to the second direction.

15. An apparatus comprising:

at least one drive electrode disposed on a substrate;

a plurality of sense electrodes disposed on the substrate;

a wiper comprising at least one arm, the wiper electrically insulated from the plurality of sense electrodes; and

a controller operable to;

drive the at least one drive electrode;

detect a plurality of charges stored by the plurality of sense electrodes; and

determine a position of the wiper based on the plurality of charges detected by the sense unit.

16. The apparatus of claim 15, wherein the wiper further comprises a rotary shaft coupled to the at least one arm of the wiper.

17. The apparatus of claim 15, wherein the wiper comprises a plurality of arms that extend in a radial direction from a rotary shaft of the wiper.

18. The apparatus of claim 15, wherein at least one radial angle formed between a first pair of adjacent arms of the wiper is different from at least one other radial angle formed between a second pair of adjacent arms of the wiper.

19. The apparatus of claim 15, the drive electrode having an annular shape.

20. The apparatus of claim 15, wherein the wiper further comprises a shaft that extends in a first direction and each of the at least one arm of the wiper extends in a second direction from the shaft, the first direction being perpendicular to the second direction.