Printing machine colour reference reader - uses optical system which splits beam into two reflected beams passing to photodetectors feeding differential amplifier

摘要

The system is designed to read reference marks carried by a moving support. The system has a luminous source and an optical system. The optical system projects onto the surface of the moving support a luminous spot. The system has a photoelectric receiver which detects the luminous flux reflected from the support. It also detects the passage of the reference marks following variations of the flux. The system separates the total luminous flux (6) into two elementary beams (9, 10). That is the total flux reflected from the support (6) and or each reference (1). The two photosensitive elements (11, 12). These elements (11, 12) are connected to the two inputs of an operational amplifier (13) connected as difference amplifier.