Resilient material variable resistor

• US 7,629,871 B2
• Filed: 02/01/2007
• Issued: 12/08/2009
• Est. Priority Date: 05/25/1999
• Status: Expired due to Fees

• Current Assignee: Forest Assets II LLC (Intellectual Ventures LLC)
• Original Assignee: AuthenTec Incorporated (Apple Inc.)
• Inventors: Rogers, Michael D., Schrum, Allan E.
• Primary Examiner(s): LEE, KYUNG S
• Application Number:
  US11/701,643
• Publication Number:
  US 20070139156A1
• Time in Patent Office: 1,041 Days
• Field of Search: 338/47, 338/69, 338/185, 338/158, 338/95, 345/157, 345/173, 345/174, 347/62, 347/161
• US Class Current: 338/69
• CPC Class Codes: H01C 10/06 adjustable by short-circuiting different amounts of the resistive element
• CPC Class Codes: H01C 10/12 by changing surface pressure between resistive masses or resistive and conductive masses, e.g. pile type
• CPC Class Codes: H01C 10/305 consisting of a thick film
• CPC Class Codes: H01C 10/38 the contact moving along a straight path
• CPC Class Codes: Y10T 29/49082 Resistor making
• CPC Class Codes: Y10T 29/49085 Thermally variable
• CPC Class Codes: Y10T 29/49101 Applying terminal
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

A variable resistance device comprises a resistive member having a resistive resilient material. A first conductor is configured to be electrically coupled with the resistive member at a first contact location over a first contact area. A second conductor is configured to be electrically coupled with the resistance member at a second contact location over a second contact area. The first contact location and second contact location are spaced from one another by a distance. The resistance between the first conductor at the first contact location and the second conductor at the second contact location is equal to the sum of a straight resistance component and a parallel path resistance component. At least one of the first location, the second location, the first contact area, and the second contact area is changed to produce a change in resistance between the first conductor and the second conductor. The straight resistance component increases or decreases as the distance between the first contact location and the second contact location increases or decrease, respectively. The parallel path resistance component has preset desired characteristics based on selected first and second contact locations and selected first and second contact areas. The first and second contact locations and first and second contact areas can be selected such that the change in the resistance between the first and second contact locations is at least substantially equal to the change in the straight resistance component or the change in the parallel path resistance component.

Claims

1. A variable resistor apparatus comprising:

first and second conductors lying in a plane and defining a gap therebetween; and

a resistive member comprising a resistive resilient material for bridging the gap and defining a variable resistance between the first and second conductors based upon a variable contact footprint, the variable contact footprint being substantially circular in shape at at least one position.

2. The variable resistor apparatus of claim 1 wherein the contact footprint varies substantially symmetrically in the plane of the first and second conductors.

3. The variable resistor apparatus of claim 1 wherein the gap has a width that is substantially constant.

4. The variable resistor apparatus of claim 1 wherein the variable resistance varies substantially linearly with a proportional change in a size of the contact footprint.

5. The variable resistor apparatus of claim 1 wherein the contact footprint is reversibly formable from the substantially circular shape to a substantially elliptical shape.

6. The variable resistor apparatus of claim 1 wherein the resistive member has substantially uniform resistance per unit area over the contact footprint.

7. The variable resistor apparatus of claim 1 wherein the resistive member is configured to change the contact footprint in response to a force substantially perpendicular to the contact footprint.

8. The variable resistor apparatus of claim 7 further comprising a joystick coupled to the resistive member for applying the force.

9. The variable resistor apparatus of claim 1 wherein the gap has a serrated shape.

10. A variable resistor apparatus comprising:

first and second conductors lying in a plane defining a serrated gap therebetween; and

a resistive member comprising a resistive resilient material for bridging the serrated gap and defining a variable resistance between the first and second conductors based upon a variable contact footprint.

11. The variable resistor apparatus of claim 10 wherein the contact footprint varies substantially symmetrically in the plane of the first and second conductors.

12. The variable resistor apparatus of claim 10 wherein the variable resistance varies non-linearly with a proportional change in a size of the contact footprint.

13. The variable resistor apparatus of claim 10 wherein the contact footprint is reversibly formable from a substantially circular shape to a substantially elliptical shape.

14. The variable resistor apparatus of claim 10 wherein the resistive member has substantially uniform resistance per unit area over the contact footprint.

15. The variable resistor apparatus of claim 10 wherein the resistive member is configured to change the contact footprint in response to a force substantially perpendicular to the contact footprint.

16. The variable resistor apparatus of claim 15 further comprising a joystick coupled to the resistive member for applying the force.