The photoreflector-based multisensor consists of four LEDs (red, blue, green, infrared) and two light-receiving sensors to detect the leading edges and width of

paper and skews in it, and to adjust its registration, head height and calibration.

At head height adjustment, the two light-receiving sensors detect infrared light reflected upon the paper to work out the head height form differences in its meas-

urement.

Carriage cover sensor

The photointerrupter-based carriage cover sensor detects the opening and closing of the carriage sensor.

When the carriage cover is closed, the sensor light is shielded by the sensor arm, enabling the sensor to detect that the carriage cover is closed.

Lift cam sensor

A photointerrupter-based sensor. After the sensor light is shielded by the flag, the lift motor is driven by a predetermined number of pulses to regulate the separation

between the printhead and platen automatically.

Linear encoder

Mounted on the back of the carriage, the linear encoder detects the position of the carriage from a slit in the linear scale during its movement.

Ambient temperature sensor

The thermostat-based ambient temperature sensor mounted on the head relay PCB detects the ambient temperature to which the carriage is exposed.

The resistance of the thermistor that varies as a function of temperature changes in the printer is transmitted the main controller via the carriage relay PCB.

The ambient temperature is used to help calibrate the head temperature sensor and detect abnormal ambient temperatures.

Head temperature sensor

The head temperature sensor detects the temperature of the printhead.

The printhead temperature is transmitted to the main controller via the carriage relay PCB.

The printhead temperature is used to help control the head drive and detect abnormal printhead temperatures.

Printhead contact sensor

The printhead contact sensor detects the status of printhead installation by electrical means.

The sensor detects the status of contact from voltage changes in the flexible cables on the carriage side that come into contact with two terminals of the printhead

with remote contact surfaces, the power terminals and GND terminal.

2-28

HeadrelayPCB

multisensor

LED(red)

Infrared sensor

Linear encoder

Carriage

cover sensor

lift cam sensor

F-2-33

LED(green)