To maintain image quality and machine quality, this machine has a low-temperature CPM mode and high-temperature CPM mode and implements 3 levels of CPM down according to the usage situation and machine state.
Low-temperature CPM mode
In a low-temperature environment, the fusing lamp cannot keep up, and it may be difficult to maintain the fusing target temperature. To handle this, the detection temperature of the thermopile (center) (TH1) is checked every few seconds, and if the detection temperature during the check is below a threshold value, the CPM is decreased by 1 level.
This low-temperature CPM reduction is performed in the following 3 levels:
<CPM down level>
Normal CPM | Level |
|---|---|
CPM down 1 | 100% |
CPM down 2 | 80% |
CPM down 3 | 65% |
Normal CPM | 50% |
Hot CPM mode
To shorten the warm-up time and reduce the TEC value, this machine employs a fusing unit with a low heat capacity.
For this reason, the temperature of those parts of the fusing belt where paper does not pass easily increases, and the outside of the paper width may get extremely hot. In order to prevent the belt breakage 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 detection temperature of the temperature sensor, or the paper passage time.
- The down-level % is a value for the case where a typical paper (Normal paper: A3/A4) passes through the SEF. There may be some differences depending on paper size/paper thickness.
<CPM down level>
Mode | Level |
|---|---|
Normal CPM | 100% |
CPM down 1 | 80% |
CPM down 2 | 50% |
CPM down 3 | 30% |
CPM down determination using a temperature sensor
The temperature sensor is checked at given intervals, and if the detection temperature is above a threshold value, the CPM is decreased by 1 level.
Since the points at which temperature tends to increase depending on the paper size, the sensor used is changed depending on the paper size.
Paper width (length) | Check sensor |
|---|---|
A3/DLT/B4 | Pressure roller thermistor (edge) (TH4) |
LT/A4 | Thermopile (edge) (TH2) |
B5/A5/B6/A6 | Pressure roller thermistor (center) (TH3) |
CPM down determination using paper passage time
Depending on the paper size, it may not be possible to determine the points on the fusing belt which tend to rise in temperature by a sensor.
Therefore, time conditions are also used to determine CPM down, and if continuous paper passage time is above a threshold value, CPM is decreased by 1 level.
(When CPM down is performed by time conditions, CPM does not increase thereafter.)