Abstract: A keyless access control and security system especially adapted for use with an automobile and including a piezoelectric permutation touchpad unit which can be affixed, without requiring bodywork, to the outside of the vehicle's door in the key cylinder aperture. The touchpad is illuminated when touched and is therefore usable in the dark. The person seeking access must enter the correct access code combination on the touchpad to open the door and/or the trunk. The touchpad is connected to a remotely located logic circuit which controls access. The circuit provides for a signal of low intensity, indicating that a correction in the code entered into the touchpad should be made and, after a time delay, an alarm of high intensity, if no correction is made. Upon activation of the alarm, the head lights are flashed, the horn is sounded, or both.

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.

Abstract: A device is disclosed which is useful to generate electric signals particularly in close quarters. The preferred embodiment is described in terms of a piezoelectric signal generator incorporated into the beltline trim of an automobile and an alternate configuration in a flat sheet metal application. The invention is discussed in terms of its ability to take advantage of already existing structural elements of its host body and its ability to be attached without putting holes in such structure.