Moving dielectric, capacitive position sensor configurations

• US 7,602,376 B1
• Filed: 10/06/2000
• Issued: 10/13/2009
• Est. Priority Date: 02/22/2000
• Status: Active Grant

• Current Assignee: P.I. Engineering, Inc.
• Original Assignee: P.I. Engineering, Inc.
• Inventors: Hetherington, Jack H.
• Primary Examiner(s): Nguyen; Jimmy H
• Application Number:
  US09/684,205
• Time in Patent Office: 3,294 Days
• Field of Search: 345156-184, 463/37, 463/38, 340/870.37
• US Class Current: 345/161
• CPC Class Codes: G05G 1/04 Controlling members for hand actuation by pivoting movement, e.g. levers
• CPC Class Codes: G05G 1/08 Controlling members for hand actuation by rotary movement, e.g. hand wheels
• CPC Class Codes: G05G 2009/0474 characterised by means converting mechanical movement into electric signals
• CPC Class Codes: G05G 9/047 the controlling member being movable by hand about orthogonal axes, e.g. joysticks for switches H01H25/04
• CPC Class Codes: G06F 3/0338 with detection of limited linear or angular displacement of an operating part of the device from a neutral position, e.g. isotonic or isometric joysticks
• CPC Class Codes: G06F 3/03543 Mice or pucks G06F3/03541 takes precedence
• CPC Class Codes: G06F 3/03548 Sliders, in which the moving part moves in a plane
• CPC Class Codes: G06F 3/0362 with detection of 1D translations or rotations of an operating part of the device, e.g. scroll wheels, sliders, knobs, rollers or belts

Abstract

A capacitive sensor configuration is capable of determining position and/or velocity for rotary or linear translation using a movable dielectric element coupled to an elongate member. The dielectric element is supported between at least one detection plate and a plurality of transmitting plates. By measuring the charge on the detecting plate, the capacitances of the assembly at a given point in time can be determined, and this measurement is used to solve for position of the member. The dielectric need not be rigid, and the dielectric'"'"'s distance from the plates does not have to be tightly controlled. The apparatus can be used to measure the position or velocity of a variety of devices, including computer peripherals such as mice, keyboards, joysticks, and other input control panels and pointing devices.

Claims

1. A capacitive position sensor configured for interconnection to a utilization device, comprising:

a stationary signal-detecting capacitor plate;

a stationary signal-transmitting capacitor plate supported parallel to, and spaced apart from, the signal-detecting capacitor plate, the transmitting capacitor plate being divided into a plurality of electrically separated segments;

a non-circular, movable dielectric element disposed between the signal detecting and signal-transmitting capacitor plates;

an elongate member having a user-manipulable proximal end and a distal end coupled to the dielectric element, the member being operative to rotate and laterally shift the element in the x or y directions in a plane substantially parallel to the stationary plates as a function of user position;

circuitry in electrical communication with the stationary plates, the circuitry being operative to (a) measure the capacitance between each segment of the signal-transmitting plate and the signal-detecting plate, (b) determine the position of the elongate member in the x and y directions as a function of the measured capacitance, and (c) determine rotation of the elongate member as a function of the measured capacitance, with or without lateral shifting of the dielectric element; and

an output for communicating the x-y position and rotation to the utilization device.

2. The position sensor according to claim 1, wherein the utilization device is a computer.

3. The position sensor according to claim 1, wherein the elongate member is a user-graspable joystick.

4. The position sensor according to claim 1, wherein the segments of the signal-transmitting plate are arcuate.

5. The position sensor according to claim 1, wherein the dielectric element is oval or egg-shaped.

6. The position sensor according to claim 1, wherein the plurality of electrically separated segment includes 3 or 4 arcuate segments.

7. The position sensor according to claim 1, wherein:

the elongate member includes a pivoting coupling between the first and second ends of the elongate member; and

the distal end of the elongate member is loosely coupled to the dielectric element so that the dielectric element remains in a plane substantially parallel to the stationary plates as the dielectric element is rotated or laterally shifted.

8. The position sensor according to claim 1, wherein:

the movement of dielectric element is constrained by the spacing of stationary plates so that the dielectric element remains in a plane substantially parallel to the stationary plates as the dielectric element is rotated or laterally shifted.

9. The capacitive position sensor according to claim 1, wherein the dielectric element has a periphery described by:

r(θ

)=r₀+a₀ cos(2θ

)+a₃ cos(3θ

).

10. A capacitive-based joystick configured for interconnection to a utilization device, comprising:

a housing having a top surface;

a stationary signal-detecting capacitor plate disposed within the housing;

a stationary signal-transmitting capacitor plate disposed within the housing parallel to, and spaced apart from, the signal-detecting capacitor plate, the transmitting capacitor plate being divided into a plurality of electrically separated segments;

a non-circular, movable dielectric element disposed within the housing between the signal-detecting and signal-transmitting capacitor plates;

a joystick lever supported for pivotal movement having a proximal end for user engagement and a distal end loosely coupled to the dielectric element, enabling the lever to rotate and laterally shift the dielectric element in x and y directions in a plane substantially parallel to the stationary plates as a function of user position;

circuitry in electrical communication with the stationary plates, the circuitry being operative to (a) measure the capacitance between each segment of the signal-transmitting plate and the signal-detecting plate, (b) determine the position of the joystick lever in the x and y directions as a function of the measured capacitance, and (c) determine rotation of the joystick lever as a function of the measured capacitance, with or without lateral shifting of the dielectric element; and

an output for communicating the user position to the utilization device.

11. The joystick according to claim 10, wherein the utilization device is a computer.

12. The joystick according to claim 10, wherein the segments of the signal-transmitting plate are arcuate.

13. The joystick according to claim 10, wherein the plurality of electrically separated segment includes 3 or 4 arcuate segments.

14. The joystick according to claim 11, wherein the dielectric element has a periphery described by:

r(θ

)=r₀+a₂ cos(2θ

)+a₃ cos(3θ

).