Three-color detection system, for industrial automated applications, diverts part of the illuminating white light to a monitor to give reference and actual color values to compensate for drift

摘要

The three-color detection system, for industrial sorting and quality control applications, has a diaphragm (7) and a lens (5) at a white light LED (6) to illuminate an object (17) at an angle (18) with a broadband light. A lens (4) gathers diffused reflected light from the object for a three-color photo-receiver (2). A monitor light channel (8) diverts a small portion of the transmitted white light to a monitor receiver (3). Its initial color signal value is a reference, stored in memory, and subsequent actual color signals are measured intermittently to compute a compensation coefficient for use as a correction factor in the reception channel.