Patent EP-0558329-A2 (EP)
Inventor: ECKERT ALTON B
IPC: G07B17/00
Filed: 1993-02-25
Abstract: A mailing machine comprising, structure for feeding a sheet in a path of travel, a fence for defining a direction of the path of travel and against which an edge of a sheet is normally registered for alignment thereof in the path of travel, structure for printing postage indicia on a sheet in the path of travel, the printing structure including a rotary postage indicia printing drum, the printing structure including structure for driving the drum, structure for controlling the sheet feeding and drum driving structure, the controlling structure including a microprocessor, the controlling structure including structure for sensing a sheet in the path of travel and providing a signal to the microprocessor when a sheet is fed into and out of blocking relationship with the sensing structure, the signal having a first magnitude when a sheet is not disposed in blocking relationship with the sensing structure, the signal having a second magnitude when a sheet is disposed in blocking relationship with the sensing structure, the second signal magnitude having a time duration corresponding to an overall length of a sheet as measured in the direction of the path of travel, and the microprocessor programmed for commencing a count when a sheet is fed into blocking relationship with the sensing structure of a predetermined time interval corresponding to a minimum overall sheet length acceptable for printing purposes determining whether the sheet is still in blocking relationship with the sensing structure at the end of the count, and implementing a shut-down routine if the sheet is not in blocking relationship with the sensing structure at the end of the count. 
     The mailing machine also comprises structure for controlling the sheet feeding structure, the controlling structure including a microprocessor connected to the sheet feeding structure, the controlling structure including structure for sensing a sheet fed into and out of blocking relationship with the sensing structure and providing a corresponding signal to the microprocessor, the signal having a first magnitude when a sheet is not disposed in blocking relationship with the sensing structure, the signal having a second magnitude when a sheet is disposed in blocking relationship with the sensing structure, the signal having a variable magnitude between the first and second magnitudes for less than a predetermined time interval when a sheet is fed into blocking relationship with the sensing structure and the sheet edge is in alignment with the registration fence, and the signal having a variable magnitude between the first and second magnitudes for at least the predetermined time interval when a sheet is fed out of blocking relationship with the sensing structure and the sheet edge is not in alignment with the registration fence; and the microprocessor programmed for successively alternately obtaining a sample of the magnitude of the signal and delaying sampling thereof for the predetermined time interval, determining whether the magnitudes of any two successive samples are both between the first and second magnitudes, and causing implementation of a shut-down routine if the magnitudes of any two successive samples are both between the first and second magnitudes.