Print Head Height Adjustment - Ricoh MP CW2201 Field Service Manual

There are two thermistors [1]. One thermistor is for black ink (K1, K2) and one thermistor is for color ink
(C, YM). These thermistors measure the temperature around the print head units inside the carriage. The
machine uses this information to adjust the flow of ink from the print heads. Monitoring the temperature
near the print heads is critical because the temperature can affect the viscosity of the ink at the ink
nozzles.
• At low temperatures, the viscosity of the ink becomes high and can slow ink flow.
• At high temperatures, the viscosity of the ink becomes low and can cause ink to spill and run.
• The adjustment is done by changing the duty (strength of electrical charge) used to activate the
piezoelectric elements that project ink through the ink nozzles of the print heads. (The amount of ink
ejected will vary directly with the amount of charge applied to the piezoelectric element.)
Temperature/Humidity Sensor
The temperature/humidity sensor [2] is mounted on the right side of the machine above the ink supply
unit. The machine uses the readings of the temperature/humidity sensor to set the duty for operation of
the ink cartridge pump motors.
• Ink is pumped to the sub tanks in very small increments, and the operation of the ink pumps must be
regulated to assure that the ink supply is constant.
• Adjustments must be made to compensate for the expansion and contraction of the ink tubes and
other parts of the ink supply system caused by fluctuation in temperature.
The readings of the K2 print head thermistor and the temperature/humidity sensor are used together to
calculate the operating temperature of the machine.
• If the machine overheats and the operating temperature exceeds the maximum temperature, the
machine will shut down automatically and will not restart until it has cooled and been cycled
off/on. The machine must be cycled off/on, even after it has cooled down to the operational
range.
• If the temperature is too low at a cold start in the morning, for example, the machine will not start
the initial cleaning cycle unit the machine has warmed up. In this case, the machine does not
require cycling off/on. The initial cleaning will start as soon as the machine has warmed up, and
then the machine is ready for operation.

Print Head Height Adjustment

The gap between the print heads and the platen can be adjusted to accommodate thick paper. Raising
the print heads and widening the gap between the print heads and the paper prevents the print heads
from abrading the paper during printing.
Printing
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