Capacitive force sensor with magnetic spring

Patent metadata

Field	Value
Publication number	US-8978487-B2
Application number	US-201213713278-A
Country	US
Kind code	B2
Filing date	Dec 13, 2012
Priority date	Dec 13, 2012
Publication date	Mar 17, 2015
Grant date	Mar 17, 2015

Abstract

The present disclosure provides a method and apparatus for a capacitive force sensor utilizing a magnetic spring. The force is applied across a body and a moveable element that are coupled by the magnetic spring. The moveable element is configured to vary the capacitance of a variable capacitor. A sensing circuit, electrically coupled to the variable capacitor, provides a force signal characteristic of the applied force. In application to a stylus pointing device, the moveable element is coupled to a moveable tip of the stylus. The force signal, which is characteristic of the force applied to the tip of the stylus, may be used to control an application executed on a host electronic device.

First claim

What is claimed is:

1. A force sensor comprising:
a magnetic spring coupled between a body of the force sensor and a moveable element that resists a force applied across the body and the moveable element along a first direction;
a variable capacitor having first and second capacitor plates, the capacitance of the variable capacitor dependent upon a position of the movable element with respect to the body along the first direction; and
a sensing circuit electrically coupled to…

Assignees

• Research In Motion Ltd
• Blackberry Ltd

Inventors

• Fergusson Andrew Ashraf
• Besperstov Iouri Petrovitch

Classifications

• G01L1/144 Primary

  Physics · mapped topic

• G06F3/03545

  Physics · mapped topic

• G06F3/0447

  Physics · mapped topic

• G06F2203/04105

  Physics · mapped topic