Abstract: A keypad unit for an access system including an outer housing having an integral bezel. A carrier is mounted within the housing, and an overlay including key zones is mounted to the carrier. A PCB assembly is suspended within the carrier by a non-compressive, but compliant encapsulating compound. The PCB assembly includes a foam layer sandwiched between a top PCB and a bottom PCB. LEDs are electrically coupled to a top surface of the top PCB. Piezoelectric transducers are mounted to the top PCB and are backed by the foam layer. The carrier may include carrier projections are in register with the key zones on the overlay and the transducers. When an operator pushes a key zone, the corresponding projection transmits the force via the carrier and the encapsulating compound to the carrier adjacent the corresponding transducer causing it to generate a voltage indicative of the pressure zone at which the force was applied.

Abstract: A keypad unit for an access system including an outer housing having an integral bezel. A carrier is mounted within the housing, and an overlay including key zones is mounted to the carrier. A PCB assembly is suspended within the carrier by a non-compressive, but compliant encapsulating compound. The PCB assembly includes a foam layer sandwiched between a top PCB and a bottom PCB. LEDs are electrically coupled to a top surface of the top PCB. Piezoelectric transducers are mounted to the top PCB and are backed by the foam layer. The carrier may include carrier projections are in register with the key zones on the overlay and the transducers. When an operator pushes a key zone, the corresponding projection transmits the force via the carrier and the encapsulating compound to the carrier adjacent the corresponding transducer causing it to generate a voltage indicative of the pressure zone at which the force was applied.

Abstract: A weatherproof electronic keypad includes a molded plastic housing, a plurality of transducers attached to the inside surface of the front wall of the housing, an electronic circuit mounted within the housing and connected to the transducers, and a graphics overlay removably affixed to the outside surface of the front wall of the housing. The front wall and overlay are sufficiently flexible that finger pressure applied to the overlay results in enough deformation of the front wall to activate the transducer underlying that portion of the inside surface. The overlay contains indicia which identify the location and function of the transducers. The overlay need not be attached to the housing as a part of manufacturing the keypad, but rather can be added in situ as part of installation of the keypad. This enables customized selection of a particular overlay in accordance with aesthetic and/or functional considerations, as well as replacement of the overlay in the field if necessary.

Abstract: An alarm condition sensor for triggering a signal incorporated in an alarm system and adapted to be mounted on a motor vehicle or other object to protect it against burglary, theft, tampering, or the like. The sensor comprises a sensing mass mounted atop a deformable substrate equipped with piezoelectric material operable to generate a signal voltage upon stressing or deformation of the substrate in response to forces effecting relative movement between the mass and the substrate. The sensor may be mounted on a cantilever spring support which enables the mass to move and thereby stress the substrate and generate a signal voltage. Voltage sensitive means responsive to voltages generated by the piezoelectric material is operable to trigger the alarm system. The sensitivity of the sensor is adjustable to vary the threshold value of the voltage operable to activate the alarm.

Abstract: The high impedance output of a touch-sensitive piezoelectric sensor is coupled directly to the high impedance input of a CMOS (complementary metal oxide silicon field effect transistor pair). The CMOS is protected on its input side by clamps which restrict the voltage swing applied to the gates to within the range defined by the positive and negative CMOS bias supply (+V.sub.DD and -V.sub.SS). The sensor produces voltages of approximately equal magnitude in response to slow acting temperature changes and quicker acting manual touching. In order to distinguish piezoelectric from pyroelectric signals, the CMOS bias is periodically and briefly shorted, to ensure a brief return-to-zero of the sensor output, thereby effectively suppressing the slow acting pyroelectric signal without interfering with sensing of quick acting piezoelectric signals.