| 摘要 |
A rotor movement sensing system in a postage meter permits detection of the printing of postage even if power is lost during the printing cycle. A sensor senses a magnet on a disk when the rotor is substantially past its home position. A second sensor has a magnetic memory element. When the magnet on the disk passes near the memory element, that element is magnetized. A Hall-effect sensor at the memory element provides an interrupt to a processor to indicate magnetization of the memory element. A winding is provided around the memory element. The processor has an output which, when asserted, causes current flow through the winding, demagnetizing the memory element. Alternatively a reed switch senses rotor rotation, a flip-flop provides a bistable latch and its output provides a datum for the processor. An interrupt routine provides that during a routine franking cycle the processor responds to the interrupt, makes record in nonvolatile memory of the occurrence of the printing cycle, and energizes the winding or flip-flop reset. This interrupt routine is executed for each franking cycle when power is continuously available.
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