Epson 4000 Service Manual - Page 146

EPSON Stylus Pro 4000 2.2.7 Multi Sensor 2.2.7.1 Overview This printer is equipped with a Multi Sensor that provides multiple sensor functions with a single sensor unit. The Multi Sensor is a photosensor with 1 light emitter and 2 light receivers and is mounted on the Carriage Unit. Light emitted from the white light LED is projected onto the paper or special pattern printed on the paper, and reading of the reflected light by the sensor receivers enables the printer to automatically perform suitable correction processing. Multi Sensor LED PW2 PW1 Revision B † Light Receivers The light receiver side has the following 2 elements for corresponding uses. „ PW1 (direct reflection light receiver) Detects paper (white) or platen (black), specifying the edge of the paper. „ PW2 (diffused light receiver) Prints a special pattern and detects differences in concentration for paper (white) and ink (8 colors). The 2 light sensor elements are identical, with the difference being the light reception angle for reflected light. In order to determine small differences in concentration, PW2 is particularly arranged in a position that will not receive the effects of erratic reflections of light reflected from the paper (especially from glossy media). Paper Platen Sub Platen Figure 2-49. Multi Sensor † Multi Sensor Functions „ Paper Edge Position Detection (Top Edge Detection/Checking Paper Cutting) „ Paper Width Detection „ Paper Edge (L/R) Detection „ Dot Missing Detection „ Auto Uni-D Adjustment „ Auto Bi-D Adjustment Operating Principles Printer Mechanism Components 146