Detection Mechanism Unit; Home Position Detection Mechanism - Epson TM U200D - B/W Dot-matrix Printer Technical Manual

Detection Mechanism Unit

The detection mechanism unit consists of the home position detection, paper detection, and
near-end detection (optional) mechanisms.

Home position detection mechanism

The home position detection mechanism consists of the detection protrusion at the left side of
the Carriage sub-ass'y and the Detector sub assembly at the left side of the base frame. It
determines the home position, identifies the carriage position, and detects Carriage sub-ass'y
operation errors.
The Detector sub assembly consists of an LED and photo transistor. When the Carriage sub-
ass'y moves, the detection protrusion passes between the LED and photo transistor and blocks
the optical axis of the photo transistor, changing the output level of the photo transistor.
The change in the output level is used as a signal to detect the movement of the Carriage sub-
ass'y.
Carriage sub-ass'y detection protrusion
Rev. B
Detector
Figure 2-11 Detection mechanism unit
Printer side
Figure 2-12 Home position detection diagram
TM-U200D/U200PD Technical Manual
Paper detector
The light is blocked
+5V
High
A
Low
GND
Signal level at A
Mechanism Configuration and Operating Principles
The light is
not blocked