HP Color LaserJet CM4730 Service Manual - Page 155

Operation sequence A microcomputer in the engine control system controls the operation sequence for the MFP. The basic operation sequence (see Table 4-1 Basic operation sequence on page 135) describes the main operational periods from the point when the MFP 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 4-1 Basic operation sequence Period Purpose Remark WAIT (wait 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. During this period, the MFP checks the toner level and detects whether the cartridges are present. The MFP also executes the pulse width modulation adjustment, color registration adjustment, and image density calibration control as required. STBY (standby period) 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 MFP ready to print. When the formatter sends a Sleep command, the MFP enters Sleep mode. INTR (initial rotation 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. When the formatter sends a print command in preparation for printing. 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 rotation period) From the end of the PRINT period until the drum motor stops. To deliver the paper out of the MFP and to clean the ETB. The last rotation period lasts until the instant the formatter sends a print command. Then the initial rotation period starts again. Operation sequence (scanner) Period (sequence) Power on Initialization Description During this time, the scanner motors rotate, the MFP checks the status of all the sensors, the scanner lamp is illuminated, the optical scan head moves from its home position, the scanner calibrates, and then the optical scan head returns to its home position. The period of time after the initial power-on sequence and before the MFP is ready to scan or copy. During this time, the scanner and ADF initialization is completed, scanner calibration is performed, and the ADF checks for media in the input tray. ENWW Basic operation 135