Service manual

Rev. B Mechanism Configuration and Operating Principles 2-9
TM-U200 Series (Type B) Service Manual
Confidential
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 assembly and the sensor sub assembly at the left side of the base frame. It
determines the home position, identifies the carriage position, and detects carriage sub assembly
operation errors.
The sensor sub assembly consists of an LED and photo transistor. When the carriage sub
assembly 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
assembly.
Figure 2-11 Detection mechanism unit
Figure 2-12 Home position detection diagram
Paper detector
Home position sensor
Printer side
The light is blocked
The light is
not blocked
Carriage sub assembly detection protrusion
Signal level at A
High
Low
+5V
GND
A