Canon BJC 50 Service Manual - Page 132

Part 4: Technical Reference BJC-50 5. DETECTION FUNCTION The printer uses HP sensor, paper end sensor, delivery sensor, inside temperature sensor, and head temperature sensor. Also, the capacity of the waste ink absorber is stored in the EEPROM. When the absorber is about to become full a warning is given and when full an error will occur. The printer detects the level of the ink remaining in the ink cartridge by counting the number of dots ejected, and indicates when the ink runs out. The ink remaining detection function operates only when the setting for the BJ controller is ON. 5.1 HP Sensor The photointerrupter type HP sensor detects the edge of the carriage in order to detect the carriage position. After the carriage senses the edge, it moves to the right, and the print head is capped at its home position. 5.2 Paper End Sensor The switch type paper end sensor detects the presence of paper. 5.3 Delivery Sensor The switch-type sensor detects whether paper has been delivered. 5.4 Temperature Sensor The temperature sensor on the control board detects the temperature inside the printer. The ASIC detects a change in the thermistor resistance that changes along with changes of the inside temperature. The ASIC converts the input analog value, which is a voltage converted from the thermistor resister to a digital value with the internal A/D converter. This value is used to control the pulse width of the head drive control signal and temperature adjustment signal. 5.5 Head Temperature Sensor The head temperature sensor in the print head detects the head temperature. The ASIC detects the diode sensor that changes as a change in voltage along with changes in the head temperature. The ASIC converts the input analog value to a digital value with the internal A/D converter. When the head temperature rises excessively, the digital value becomes large, which can stop ejecting the ink from the head. TH1 HP Sensor Delivery Sensor Paper End Sensor Figure 4-31 Sensor Location 4-44