C. Paper Jam Detection The following paper sensors are installed to detect whether the paper is present or not and whether the paper is fed normally or not. � Reversed paper sensor (PS703) � Duplexing unit pick-up sensor (PS701) The microprocessor (CPU) determines whether paper is jammed or not by checking whether paper is present or absent at the sensors at check timing stored in the memory. If the CPU determines that a jam has occurred, it stops duplex feeding and notifies the jam occurrence to the engine controller. 1. Pick-up delay jam The CPU assesses a pick-up delay jam if the pre-feed sensor (PS102) does not detect the leading edge of the paper within the prescribed period of time (about 2 sec.) after the paper was picked up, or if the top of page sensor (PS103) does not detect the leading edge of the paper within the prescribed period of time after the start of duplex pick-up. 2. Reverse delay jam The CPU assesses a reverse delay jam if the reversed paper sensor (PS703) does not detect the leading edge of the paper within the prescribe time (about 2.2 sec.) after the fixing unit delivery sensor 1 (PS501) detects the leading edge of the paper. 3. Reverse stationary jam The CPU assesses a reverse stationary jam if the reversed paper sensor (PS703) does not detect the trailing edge of the reversed paper within the prescribed period of time (about 4.2 sec.) after detecting the leading edge. 4. Duplexing unit pick-up delay jam The CPU assesses a duplex pick-up delay jam if the duplexing unit pick-up sensor (PS701) does not detect the leading edge of the paper within the prescribed period of time (about 1.5 sec.) after the reversing is completed. 5. Duplexing unit pick-up stationary jam The CPU assesses a duplex pick-up stationary jam if the duplexing unit pick-up sensor (PS701) does not detect the trailing edge of the paper within the prescribed period of time (about 4.3 sec.) after the duplexing unit pick-up starts.
