Epson 3800 Service Manual - Page 56

EPSON Stylus Pro 3800/3800C/3850 2.7 Ink Mark Sensor This printer is equipped with the ink mark sensor functioning as multi sensors. The sensor, located on the bottom of the carriage unit, is a diffuse reflective photointerruptor that is comprised of a light emitting part (white LED) and a light receiving part (photoreceiver). The white LED emits light against the paper or dedicated print pattern printed on paper and the photoreceiver reads the reflected light. According to the reflected light read by the receiver, the printer calculates correction values to perform proper corrective actions. The Ink mark sensor is used for the following adjustments. † Auto Bi-D Adjustment The sensor scans predetermined patterns printed for the adjustment and detects the highest density pattern among them. According to the detected result, the printer calculates Bi-D correction values automatically. † Auto Uni-D Adjustment The sensor scans predetermined patterns printed for the adjustment and detects the highest density pattern among them. According to the detected result, the printer calculates Uni-D correction values automatically. † Auto Nozzle Check The sensor scans a nozzle check pattern. The pattern is printed with the all nozzles and each nozzle prints one block. If there is a clogged nozzle, the corresponding block will not be printed and detected by the sensor, and a head cleaning is performed automatically. OPERATING PRINCIPLES Ink Mark Sensor Revision A 56