Mechanism Details

Drive

The ITB [A] is driven by the ITB motor [C] through a gear and the ITB drive roller [B].

The ITB drive shaft encoder sensor [D] detects the speed of the ITB motor.

Transfer Bias

Bias is applied to the back of the ITB through each image transfer roller. A negative bias is applied to the ITB bias roller in order to improve image transfer to damp paper (repulsive transfer method) The power pack installed in the ITB unit supplies each bias.
Only Pro C5200S/C5210S has the AC/DC transfer method. Toner transfer to paper that has indentations is improved by switching alternately between DC transfer and AC transfer.

MP C6503/MP C8003

Pro C5200S/C5210S

ITB Contact / Separation

The ITB is separated from the color drums during black-and-white printing in order to prevent color drum (PCU) degradation.

In a black-and-white / color mixed job, the ITB separates from the color drums for black pages.

In black-and-white printing, the Y, M, and C drums (color drums) do not contact the ITB.

The ITB contacts only the K drum (black) in the default position. In color printing, the ITB [C] is pushed up by the ITB lift motor [A] through the cam [B] in order to contact the color drums. In black-and-white printing, only the K drum contacts the ITB. The ITB lift sensors detect contact/separation status.

For color printing after black-and-white printing, black-and-white printed paper exits the ITB unit, and then the ITB lift motor [A] turns on and pushes up the ITB in order to contact the ITB against the color drums (feed timing is controlled to make the interval between the sheets longer).

Image Transfer Speed / Belt HP

The feedback control of ITB speed is done during black-and-white printing, color printing, and MUSIC operation in order to improve color registration.

The ITB drive shaft encoder sensor [C] attached to the ITB drive shaft monitors the rotation speed of the ITB motor. The ITB driven shaft encoder sensor [B] attached to the ITB driven roller shaft monitors the rotation of that roller. Readings from both encoders are used to control the speed of the ITB motor. This process is known as CVEC (see below for more details).

The ITB home position sensor [A] detects the home position of the ITB.

Image Location Correction

To prevent color registration errors, the machine makes a pattern on the ITB and reads it with the ID/MUSIC sensor [A] that is installed near the drive roller of the ITB.

Thermal Control

The anti-condensation heater [A] prevents condensation from forming on the ITB. It turns on when the main power switch is turned off.

The temperature/humidity sensor [B] is on the bottom of the machine (under the lowest PFU). It monitors the temperature and humidity inside the machine.

CVEC (Compensation function of belt speed Variation of Encoder roller Cycle)

CVEC (Compensation function of belt speed Variation of Encoder roller Cycle) is a technology designed to stabilize the positioning of the belt and control the speed fluctuation of the ITB.

In many older models, an encoder monitors the speed of the driven roller. But errors in speed detection could occur because of eccentricities in the encoder or vibrations of the roller shaft. Also, the conventional machines reduce color deviation by relating station pitches with the circumference of a driven roller, but it is difficult to eradicate the occurrence of belt speed fluctuation and position deviation completely.

In CVEC technology, two encoders control the speed of the ITB. From the difference between the detected values from the encoders on the drive roller and on the driven roller, the speed fluctuation of the driven roller is calculated. From this, the phase amplitude of the driven roller that affects the fluctuation rate is calculated. Then the ITB motor is controlled to counteract the phase differences. With CVEC, fluctuation in speed is reduced by more than half.

CVEC-related SC codes are shown below (Logging only)

See “Troubleshooting” for finding possible causes and countermeasures.