The ETB unit consists of the ETB, ETB tension roller, ETB feed roller, ETB engaged roller, attraction roller and transfer roller. The ETB motor (M5) drives the

ETB feed roller, and as the feed roller rotates, the ETB rotates. Other rollers than the ETB feed roller rotate together with the ETB movement. The ETB running is

controlled with extreme stability and precision without any slight meandering, ruffling, or vibration.

During the printing operation, the picked up paper is attracted to the ETB and fed while the toner image is transferred onto it. In addition, the ETB is also used for

the controls of color misregistration as well as image stabilization. The pattern images for the color misregistration or image density determination is formed on the

ETB. Especially in full-color printing, the image is formed by piling up four colors' toner, therefore extreme precision is required for ETB running.

The controls performed in the ETB unit are the following.

- Automatic bias control

- ETB cleaning

- Transfer roller engagement/disengagement control

2.4.4.2 Automatic bias control

0013-7508

/ i-SENSYS LBP5360 / i-SENSYS LBP5300

This control is to monitor the resistance of transfer roller, attraction roller, and ETB in order to prevent poor transfer caused by the aged deterioration or variation

inherent.

When the printing operation is started, the DC controller electrifies constant value of current to the transfer roller (for Black) and the attraction roller, and detects

the voltage value of the current flow. Accordingly the DC controller obtains resistance information on the transfer roller, attraction roller, and ETB. The DC con-

troller applies the appropriate bias to the roller for transfer and attraction depending on the detected voltage. Thus, the steady image quality is obtained.

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