Internal Temperature Sensor; Head Temperature Sensor; Asf Sensor; Carriage Encoder/Paper Feed Encoder - Canon S600 Service Manual

S600

1.4.6 Internal temperature sensor

The internal temperature sensor (TH201) on the control board detects the printer's
internal temperature in order to control print head driving. When the printer's
internal temperature changes, the thermistor's resistance also changes accordingly
and the change in the resistance is detected by the MPU as a change in voltage. The
analog value that is input is converted to a digital value by an internal A/D converter.

1.4.7 Head temperature sensor

The head temperature sensor is in the BJ cartridge's print head. If the head
temperature is abnormally high, the sensor detects the head temperature and the
abnormal head temperature error is issued to stop printing operation. When the head
temperature changes, the diode sensor changes accordingly and the voltage change is
detected by the MPU. The analog value that is input is converted to a digital value by
an internal A/D converter.

1.4.8 ASF sensor

The ASF sensor detects the ASF paper feed rollers' initial position. It detects the paper
feed rollers' position during ASF initial positioning and paper feeding.

1.4.9 Carriage encoder/paper feed encoder

With the encoder, the light from the LED passes through the encoder film and enters
the photo IC. It is converted into a digital electrical signal when the encoder rotates or
when the carriage moves.
With this feedback signal, the printer controls the driving of the DC motor.

1.5 Other Sensing Features

Besides the sensors described above, the printer has the following detection features.

1.5.1 Waste-ink detection

For print head maintenance, ink is ejected by the maintenance jet or purged by the
recovery operation. The ejected or purged ink is absorbed by the waste-ink absorber.
If the waste-ink absorber discharges ink because it contains more ink than it can
absorb, the printer may leak ink.
To prevent ink from leaking, the waste-ink absorber's full capacity is detected by
estimation.
The printer calculates the amount of waste ink produced by the maintenance jet and
recovery operations by referring to the ink dot counter. While taking ink evaporation
into account, if the estimated waste-ink amount exceeds 95% of the waste-ink
absorber's capacity, the waste-ink warning is issued when the power is turned on. If
the estimated waste-ink amount reaches 100% of capacity, the waste-ink full error
occurs.

1.5.2 Print head detection

The presence of the print head is detected with the AD value obtained from the head
temperature sensor. If the temperature counted in reverse from the AD value is lower
than the absolute 0 degree (an impossible value), the printer will assume that there is
no print head.
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Part 3: Technical Reference