| 摘要 |
A continuous web or laminate (32) of flexible material is indexed through a punch press (44) whereat holes of different shapes and sizes are punched in repetitive patterns through successive sections of the laminate. The laminate (32) is then moved beneath a light source (48) so that light passes through the holes and is sensed by a light-sensing camera (52) which laterally and cyclically scans at a rapid rate the underside of the moving laminate. During the rapid scanning by the camera (52), each hole may be scanned many times due to the size and shape of the hole. Consequently, light is sensed many times for the same hole and a corresponding number of signals are developed by the camera. A hole counting system (46), which receives the developed signals from the camera (52), includes a delay-and-compare circuit (66) wherein each signal related to a given hole is delayed by one scan cycle and compared with the next signal related to the same hole. When the given hole has passed, the camera (52) does not sense light on the next scanning cycle. This condition, when compared with the immediately previous light-sensed condition, results in the development of an output hole-count pulse from the delay-and-compare circuit (66). The count pulses of each section of the laminate (32) are fed to a counter-comparator circuit (70), and are counted and compared with a desired preset count for each section. If the actual and preset counts of a selected number of successive sections do not compare, an alarm is sounded and a signal is fed to the punch press (44) to stop the punching operation.
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