Detection Mechanism Unit; Home Position Detection Mechanism - Casio UP-250 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 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.
Carriage sub assembly detection protrusion
Home position sensor
Figure 2-11 Detection mechanism unit
Printer side
Figure 2-12 Home position detection diagram
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Paper detector
The light is blocked
+5V
High
A
Low
GND
Signal level at A
The light is
not blocked