AUTOMATIC STAMP MACHINE

摘要

Automatic stamp machine for automatically dispensing value-denominated stamps, provided with a chassis, a drive system with a stepping motor, an optical measuring system for consecutively scanning a progressively moved strip of stamps which are fed from a stamp roll and are each separated from one another by a separating edge and for generating a signal which represents the degree of light attenuation, a processing and control unit for examining the light attenuation signal to determine the separating edge, and a cropping system for cutting off an externally specified number of stamps under the control of the processing and control unit. The optical measuring system is designed to measure the average light attenuation, at least over a portion of the width of the stamp strip, at discrete length intervals with high resolution. The optical measuring system is synchronised with the drive system so that a light measurement takes place for every step of the stepping motor per said length interval. The digitally designed processing and control unit determines the separating edge on the basis of detection criteria and is of self-adjusting design, the stamp parameters such as length and light attenuation and their variation being automatically determined and processed. During an initialisation phase the processing and control unit determines a threshold value for stamp detection by storing a histogram of measured values of light attenuation for a number of stamps in the data memory, the threshold, tr, being calculated as follows: tr = Min + A.(Mod - Min), where Min is the minimum value of the light attenuation found and Mod is the mode found, i.e. the value occurring most, and A is a weighting factor.