Interlink Electronics, Inc.

Mark C Pickett

Robert Matthew Martinelli

Stuart I Yaniger

Wendell W Ritchey

John K Martinelli

Stuart J Yaniger

A touchpad assembly and method for providing a signal to a computer indicative of the location and applied pressure of an object touching the touchpad assembly is provided. The touchpad assembly includes X and Y position and pressure sensitive semiconductor resistance sensor layers. The X and Y sensors have a pair of spaced apart X and Y conductive traces running across opposite ends such that a resistance RX connects the pair of X traces and a resistance RY connects the pair of Y traces. The X and Y sensors come into contact at a contact point when an object asserts a pressure on the touchpad. The contact point is connected to each trace by a variable pressure resistance RZ associated with the X and Y sensors and variable position resistances of the X and Y resistances. First and second pair of timing capacitors are connected to respective ones of the pairs of X and Y traces. A microprocessor controls and monitors charging time of the capacitors to determine the position and asserted pressure of the object touching the touchpad.

Force sensing semiconductive touchpad

A thermally stable, mass-producible pointing device (10) producing an analog signal proportional to an applied force comprises actuator (20), including an arm (22) and a force transfer member (26), a connector (44), and a sensor (50). The connector maintains the force transfer member in contact with the sensor yet allows the force transfer member to change dimensions with ambient temperature without inducing stresses detectable by the sensor. In a preferred embodiment, the connector comprises an elastomeric adhesive and the sensor comprises a force-sensing resistor. The force transfer member is prevented from coming out of the assembly either by a retainer (12) comprising a shell or a potting compound retaining the force transfer member but permitting thermal expansion or contraction of the force transfer member. The force transfer member typically has a rounded or bevelled bottom surface (28) so the actuator rocks under an applied force. The area of the bottom surface of the force transfer member transferring the force changes as the actuator rocks, and the force is transferred to the sensor at a single contiguous area whose position changes in response to a change in force.

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Camarillo, CA, United States of America

Mark C Pickett