Sensors - Citizen CLP-621 Technical Manual

(3) Sensors

(3-1) Head up sensor
The head up sensor is used to detect the head position (up or down). This sensor uses a
photointerrupter.)
When the head block is closed (in the down position), the protrusion "A" of the head block
is engaged in the head up sensor, and the light emitted from the LED of the
photointerrupter is blocked by the protrusion "A". Thus, the phototransistor turns OFF, and
pin 117 (HDUSENS) of IC1 (CPU) goes to "High" level.
When the head block is opened (in the up position), the protrusion "A" is disengaged from
the head up sensor, and the light emitted from the LED reaches the phototransistor. Thus,
the phototransistor turns ON and pin 117 (HDUSENS) of IC1 (CPU) goes to "Low" level.
IC1
CPU
117
HDUSENS
D19
Head Up: Low
Head Down: High
+3.3V
R124
R115
R116
P220
C75
Head Block
Head Up Sensor
(SA, Head Up Sensor PCB)
+3.3V
CN9
R114
1
2
3
C74
[Main PCB]
Head Block "Up" position
A
A
SA, Head Up Sensor PCB
Head Block "Down" position
A
SA, Head Up Sensor PCB
2-21
2-2. Operation of Control Parts
Head Up Sensor
[Head Up Sensor PCB]
Photo
Interrupter
Photo
Interrupter
CLP-621 & CLP-631