HP 4600 Service Manual - Page 135

Operation sequence A microcomputer in the engine control system controls the operation sequence for the printer. The basic operation sequence (see Table 5-1 Basic operation sequence) describes the main operational periods from the point when the printer is turned on until a print operation is completed and each motor stops rotating. NOTE In the following table, "ETB" stands for "electrostatic transfer/transport belt." Table 5-1 Basic operation sequence Period Purpose Remark WAIT (wait period) STBY (standby period) From the time the power switch is turned on until the ETB cleaning is completed. To clear a potential on the drum surface and to clean the ETB. From the end of the WAIT or LSTR period or last rotation until the formatter inputs a print command or until the power is turned off. To keep the printer ready to print. During this period, the printer checks the toner level and detects whether the cartridges are present. The printer also executes the pulse width modulation adjustment, color registration adjustment, and image density calibration control as required. When the formatter sends a sleep command, the printer enters PowerSave mode. INTR (initial rotations period) From immediately after the formatter inputs a print command until the TOP signal is sent to the formatter. To stabilize the photosensitive-drum sensitivity in preparation for a print operation. PRINT (print period) From the end of the INTR period until the leading edge detection sensor detects paper and then turns off the transfer positive bias. To form an image on the photosensitive drum according to the video signal input from the formatter and to transfer the toner image to the paper. After the power is turned on, the cartridge is cleaned every 35 pages and the ETB is cleaned every 100 pages. LSTR (last rotations period) From the end of the PRINT period until the ETB motor stops. To deliver the paper out of the printer and to clean the ETB. The last rotations period lasts until the instant the formatter sends a print command. Then the initial rotations period starts again. ENWW Basic operation 119