HP Color LaserJet Enterprise CM4540 Service Manual - Page 86

The developing-roller engagement and disengagement control operates as follows: When the product is turned on and when each print job is completed, all four of the developing units are disengaged from the photosensitive drums. ● The drive of the developing disengagement motor rotates the developing disengagement cam. ● As the cam rotates, the developing unit engages with or separates from the photosensitive drum. When the print mode is full color, the developing units engage with the drums. When the print mode is black-only, only the black developing units engages with the drum. The DC controller determines a developing disengagement motor failure and notifies the formatter when it does not detect a specified signal from the developing disengagement sensor during the developing unit engagement and disengagement operation. Intermediate transfer belt (ITB) unit The ITB unit accepts the toner images from the photosensitive drums and transfers the completed image to the paper. The ITB unit has the following main components: ● ITB ● ITB drive roller ● ITB-drive roller ● Primary-transfer roller ● ITB cleaner The ITB motor drives the ITB drive roller, which rotates the ITB. The motion of the ITB causes the primary transfer rollers to rotate. The ITB cleaner cleans the ITB surface. Figure 1-26 ITB unit DC controller ITB ITB cleaner 34 Chapter 1 Theory of operation M1 ITB motor ITB drive roller Primary transfer roller ENWW