US 5,515,040 A · Methods of self-calibration for a key-type mouse

Abstract

This invention relates to methods of self-calibration for computer display cursor positioning devices imbedded within a computer keyboard key (sometimes referred to herein as a "key-type mouse") or other pointing device. A plurality of Force Sensitive Resistor grids ("FSRs") or other pressure sensitive sensors are used to detect relative pressure applied in various directions to a predetermined key of a computer keyboard. An RC circuit is used to indirectly read the values of the FSRs. A predetermined delay period is associated with each sensor followed by a measurement period. The resistance of the FSR is related to the measurement period taken to reach a given voltage value after the predetermined delay period. A positive or negative offset to the predetermined delay period adjusts the time necessary for the RC circuit to reach a predetermined bias voltage value. By breaking the charging time into a delay period and a measurement period the amount of time that the keyboard controller or microprocessor must spend devoted to watching the voltage across the RC circuit for the moment when it reaches V.sub.CC is reduced, improving the operation of the keyboard.

Claims2

Dependent claims

A method of self-calibration for an FSR-type force detecting sensor associated with a typing key in a computer keyboard including the steps of:

charging an RC circuit comprising a fixed capacitor and the FSR-type force detecting sensor from a first voltage value to a second voltage value over a period of time comprising a first period and a second period to obtain a present calibration state of the FSR-type force detecting sensor;
charging the RC circuit during said first period having a predetermined delay time to increase the first voltage value;
charging the RC circuit during said second period having a variable delay time which begins at the end of said predetermined delay time and ends when said RC circuit has reached said second voltage value;
generating a numerical value associated with said variable delay time;
detecting whether or not the typing key was depressed either just prior or just subsequent to said periods of time and continuing with the self-calibration for the FSR-type force detecting sensor only if the typing key was not so depressed;
and
if said numerical value is out of range of a predetermined bias value plus or minus a predetermined tolerance value, adjusting the length of said predetermined delay time in response to the magnitude of the difference between said bias value and said numerical value multiplied by a predetermined calibration rate to set a new value for said predetermined delay time which calibrates the FSR-type force detecting sensor.

4 more elements

Dependencies are inferred from the claim text.

Methods of self-calibration for a key-type mouse

Life of this patent

Methods of self-calibration for a key-type mouse

Life of this patent

Abstract

Claims2