Multi Sensor; Light Receivers - Epson Stylus Pro 4400 Service Manual

EPSON Stylus Pro 4400/4450/4800/4880/4880C

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.
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
Multi Sensor
LED PW2 PW1
Paper
Sub Platen
Printer Mechanism Components

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).
Revision C
145