Security system for unattended printing mechanism

Abstract

A security system for an unattended printing mechanism, such as that found in an automatic teller machine. The security system has a programmable microprocessor which sends data to a journal printer and actuates a journal motor that controls the rotation of the paper take-up drum. A timing disk is rotationally attached to the take-up drum. A sensor mounted adjacent the timing disk senses the rotation of the timing disk and the rotation of the take-up drum. As the timing disk rotates, the sensor generates alternating high and low signals. The sensor signals are fed to the microprocessor, which assesses the number of high/low signals, and the amount of paper being fed to the take-up roll. When it does not see a proper number of high-to-low transitions for a given amount of journal motor rotation, the microprocessor provides a signal that a jam has occurred in the printing system. The microprocessor continually monitors the sensor signals. When the journal motor is not running, transition signals received by the microprocessor from the sensor indicate tampering with the take-up roll and then the monitoring center is altered.