Mechanism

QSU-DH Fixing System

The heating sleeve belt is driven by drag rotation following the pressure roller, and presses a nip pad against the pressure roller to fix toner to the paper.

The fusing lamp emits light, and the area of the fusing sleeve belt which is heated moves in an anticlockwise direction so that heat is transmitted up to the contact point with the pressure roller.

• Fusing lamp
   There are two lamps
   Lamp power:

  Center	800 W
  Edge	412 W

• Nip pad
  Presses against the Pressure roller to form a fusing nip. The top surface is covered with a slippery sheet.
  Light Shielding plate and Heat Conduction Plate
  The heating sleeve belt unit in this model has light shielding and heat conduction plates. These prevent the fusing sleeve from damage caused by temperature increase. Otherwise, this could happen at parts of the sleeve where paper does not pass by during a multi-page job using paper widths that are less than the full width of the sleeve.
  When handling an A3 (SEF) or A4 (LEF) sheet
  A cylindrical-shaped light shielding plate [C] covers the ends [D] of fusing lamp [A] where paper does not pass by, to prevent the temperature from rising at those places. 
  

  	Description
  [A]	Area where the fusing lamp lights up
  [B]	Print width of A3 (SEF) / A4 (LEF)
  [C]	Light shielding plates
  [D]	Areas where paper does not pass by and that would heat up without the light shielding plates

  When handling an A4 (SEF) or smaller sheet
  The machine lights up only the fusing lamp for center [A]. At this time, the temperature increases around the area [D] where paper does not pass. This is the gap between the lit part of the fusing lamp [A] and the edge of the sheet being fed.
  To prevent the heating sleeve belt unit from damage caused by the temperature increase, heat conduction plates [C] which are made of a highly heat conductive material are attached to the nip pad [B] to release the heat.
  

  	Description
  [A]	Area where the fusing lamp lights up
  [B]	Nip pad
  [C]	Heat conductive plates
  [D]	Areas where paper does not pass by and that would heat up without the heat conducting plates
  [E]	Print width of A4 (SEF)
  [F]	Print width of small size

• Reflector
  Transmits heat efficiently to the left of the fusing belt.
• Flanges
  Situated on both ends of the fusing belt. They maintain the shape of the belt.

Fusing Drive

The pressure roller [B] is driven by the fusing motor or fusing/paper exit motor [A] (depending on the model). The fusing belt [C] is driven by the pressure roller (drag rotation).

Pressure Release Mechanism

To easily remove paper in the event of a jam in the fusing unit, a pressure release mechanism is provided.

The pressing or releasing movement is applied together when the right cover [A] opens/closes: When the right cover is closed, pressure is applied. When the right cover is open, the pressure is released.

Fusing Temperature Control

• Warm-up mode
  After power ON, fusing warm-up begins. The fusing motor or fusing/paper exit motor is switched ON, the halogen heater is energized, and the fusing temperature is increased to the “reload target temperature.”
  When the fusing warm-up is completed, the fusing motor or fusing/paper exit motor is switched ON for a certain time, and the fusing temperature is maintained at the “reload target temperature.”
• Standby mode
  After fusing reload, when a certain time has elapsed, power supply to the halogen heater is switched OFF, and the fusing motor or fusing/paper exit motor is switched OFF. At the same time, the temperature is maintained at the “standby target temperature (SP1107-001)” by the halogen heater.
  In standby mode, the fusing motor or fusing/paper exit motor is switched ON intermittently.
• Printing ready mode
  After returning to standby mode, the halogen heater is re-energized, and the fusing temperature is raised to the “printing ready target temperature.” If printing is not required, the machine again enters the standby mode after a certain time has elapsed.
  If printing is required during return to standby, the halogen heater is energized, the fusing temperature is increased to “target temperature after reload/after paper feed,” and the print job starts.

CPM Down Control

To maintain image quality and MFP quality, this MFP has a low-temperature CPM mode and high-temperature CPM mode, and implements 3 levels of CPM down according to the usage situation and MFP state.

• Low-temperature CPM mode
  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 level.
  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 MFP 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 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

  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 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.

  Paper width	Sensor used
  A3/DLT/B4 (SEF)	Fusing thermistor (pressure roller end)
  LT/A4 (SEF)	Fusing thermopile (end)
  B5/A5/B6/A6 (SEF)	Fusing thermistor (pressure roller center)

• 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 belt which tend to rise in temperature.
  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.)