Brother MFC9100C Service Manual page 29

• Head thermistor which allows the controller to control the temperature of the print head.
According to the change of the thermistor's internal resistance monitored, the control circuitry
regulates the drive voltage applied to the head's piezoelectric ceramic actuators since the
viscosity of the ink varies depending upon the temperature. If the head thermistor detects
5.5°C or below, or 48°C or higher after two hours of powering-on state, the equipment stops
printing and stores print data into the DRAM.
• Head property EEPROM which stores the head property information. If you set the print head
unit on the carriage, the control circuitry on the main PCB reads the information and regulates
the drive voltage applied to the head's piezoelectric ceramic actuators.
• Purge cam HP switch which detects whether the purge cam is in the home position.
The above photosensors are a photointerrupter consisting of a light-emitting diode and a light-
sensitive transistor. Each of them has an actuator separately arranged as shown on the next
page.
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