F.m.e. Corporation

Elizabeth A Simon

John G Haines

Ward J Payn

Albert L Pion

Onni W Niemi

Daniel P Leonard

John V McDonald

Christopher M Mayer

An improved electronic postage meter which includes a microcomputer (17), redundant memories ('BAMs') (35a-b), and fault flip-flops (30a-b). Improved circuitry for controlling the writing to the BAMs includes a timer ('BAM-protection timer') (40) coupled to the write-enable input of each of the BAMs. The BAM-protection timer has a trigger input (43) coupled to the microcomputer. The microcomputer is programmed to execute an instruction to generate a triggering signal at the BAM-protection timer's trigger input immediately prior to executing an instruction to write to the BAM. This opens a window for writing; the duration of the window is set to be just long enough to allow the completion of the write operation. The fault flip-flops, once set, unconditionally prevent writing to the BAMs, regardless of any other signals that might be present. The setting of the fault flip-flops is controlled by a first timer ('watchdog timer') (60) and a second timer ('second-chance timer') (62). In normal operation, the microcomputer periodically generates a trigger signal for the watchdog and second-chance timers. The watchdog interval exceeds the maximum interval between triggers under normal conditions. If a trigger is not received, the watchdog timer resets the microcomputer. The second-chance interval is longer than the watchdog interval, so that the second-chance timer times out and sets the fault flip-flops only if the restart still fails to produce a trigger signal within the specified time.

Electronic meter circuitry

A postage meter stepper motor module for use in a postage meter of the type having a base supporting a rotatable main shaft to which a printhead is mounted. The main shaft has a number of value rods mounted to it. The outer ends of the value rods are coupled to the printhead so movement of the value rods parallel to the main shaft axis changes the chosen value print character at the printhead. The stepper motor module includes a stepper motor frame mounted to the base at a chosen position relative to the main shaft. A stepper motor is mounted to the stepper motor frame. A yoke couples the stepper motor to a chosen axial position along one of the value rods through a coupler ring. The coupler ring and yoke allow the value rod to rotate freely about the main shaft while maintaining the axial position determined by the stepper motor. The stepper motor and yoke are coupled by a rack and pinion arrangement to translate the rotary motion of the stepper motor to the linear motion of the yoke.

Postage meter stepper motor module

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Berkeley, CA, United States of America

Elizabeth A Simon