HP Color LaserJet CM1312 Service Manual - Page 104

Jam detection The product uses the following sensors to detect the presence of media and to check whether media is being fed correctly or has jammed: ● Cassette media-presence sensor ● Top-of-page sensor ● Loop sensor ● Fuser delivery sensor The product detects the following jams: ● Pickup delay jam ● Pickup stationary jam ● Delivery delay jam ● Delivery stationary jam ● Fuser wrapping jam ● Residual media jam Pad transfer The product uses a pad transfer method for the primary transfer operation. The pad transfer method stabilizes an image compared to the conventional separation roller method. The wider nip width between the transfer pad and the photosensitive drum improves the transfer performance. Multiple-feed prevention The product uses a separation roller to prevent multiple sheets of media from entering the product. The paper separation roller follows the rotational direction of the pickup roller because it does not have its own driving force. ● Normal-feed: The separation roller is driven by the pickup roller through a sheet of print media. That is, the separation roller rotates in the media feed direction. ● Multiple-feed: The low friction force between the sheets weakens the rotational force from the pickup roller. The separation roller is limited in its rotational force and it does not rotate with such a weak driving force from the pickup roller. Since the separation roller does not rotate, the multiple sheets do not feed into the product. 90 Chapter 5 Theory of operation ENWW