Ricoh SP 8400DN Field Service Manual page 844

Ricoh a3 size black and white laser printer.

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In a low-temperature environment, the fusing lamp cannot keep up, and it may be difficult to maintain the

target temperature. To handle this, the detection temperature of the fusing center thermopile is checked at

given intervals, and if the detected temperature is below a threshold value, the CPM is decreased by 1

This low temperature CPM reduction is performed in the following 3 levels:

CPM down level

Hot CPM mode

To shorten warm-up time and reduce the TEC value, this printer employs a fusing unit with a low heat

For this reason, the temperature of those parts of the fusing belt where paper does not pass easily increases,

and outside of the paper width it may get extremely hot. In order to prevent the belt from breaking due to

this excessive temperature rise, CPM down is implemented depending on the usage conditions. CPM down

can be implemented in the following 3 levels depending on the detected temperature at the temperature

sensor, or the paper passage time.

The down level % is a value for the case where a typical paper (Normal paper: A3/DLT/LT/A4)

passes through the SEF. There may be some differences depending on paper size/paper thickness.

CPM down level

CPM down determination using a temperature sensor

The temperature sensor is checked at given intervals, and if the detected temperature is above a threshold

value, the CPM is decreased by 1 level.

Since the points at which temperature tends to increase depend on the paper size, the sensor used is

changed depending on the paper size.

A3/DLT/B4 (SEF)

B5/A5/B6/A6 (SEF)

CPM down determination using paper passage time

Depending on the paper size, it may not be possible to use a sensor to determine the points on the fusing

Fusing thermistor (pressure roller end)

Fusing thermopile (end)

Fusing thermistor (pressure roller center)

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