Abstract: A pointing device for use with computers and other electronic systems incorporates an array of resistive strain gauges on the surface of a substrate. The strain gauges exhibit resistance changes in response to stress or strain applied to the substrate by the movement of a joystick attached to the substrate, the resistance changes being proportional to the extent of movement of the joystick The strain gauges are electrically connected to control circuitry that successively establishes a series of voltage dividers across different ones of the strain gauges to measure the resistance of each of the strain gauges. From those measurements the position of the pointing device may be determined by comparing the measured resistances with known resistance values that correspond to a neutral stick position.

Abstract: A force transducer having a post connected to an underlying substrate having a plurality of strain gauges, is protected from otherwise damaging static electric discharge current using a grounding guard. The guard is preferably a flat conductive member having an aperture for receiving the post and a tab for connection to electrical ground. The guard surrounds the post and overlays the substrate to channel such current away from delicate strain gauges and other electronics. In the preferred embodiment the aperture is formed by bending up a plurality of flaps cut into the guard and bent up to receive the post in press-fit engagement.

Abstract: A security system uses a base unit and a portable transceiver which cooperate to provide automatic monitoring of a secure perimeter. An intrusion sensor is employed to activate a transmitter for emitting a selected frequency wave energy challenge transmission upon the detection of an intruder either outside the perimeter or entering the perimeter. If the intruder has the portable transceiver present to receive the challenge transmission, it automatically emits a responsive wave energy signal as an acknowledgment. A base unit receiver detects the acknowledgment signal and prohibits alarm action. If no acknowledgment signal is received, then either a warning or an alarm is triggered at the base unit. The system does not require manual control. The several distinct wave energy signals can be chosen from among various available radio frequency electromagnetic, and audible or ultrasonic acoustic, waves.