HP LaserJet 4v/mv Service Manual - Page 90

Basic Sequence of Operation The Formatter PCA and the DC Controller PCA share information during printer operation. The Interface PCA forms a link which operates as a serial data bus. This allows printer status, command, and dot-image data to be passed between the two PCAs. Figure 5-15 shows the general timing of the printer events. The following events take place during normal printer operation: Table 5-2 Printer Timing Period Timing Purpose WAIT From power ON to the end of Main Motor Clear the drum surface potential and initial rotation. clean the Transfer Roller. STBY (standby) From the end of the WAIT or the LSTR period until the input of the PRNT signal from the Formatter. Or from the end of the LSTR period until power OFF. Maintain the printer in ready state. INTR (initial From the input of the PRNT signal from rotation) the Formatter until the laser diode intensity has been stabilized. Stabilize the photosensitive drum sensitivity in preparation for printing. Also clean the Transfer Roller. PRNT From the end of initial rotation until the Scanner Motor stops. Form images on the photosensitive drum based on the /VDO signal from the Formatter and transfer the image to paper. LSTR (last From the primary voltage (DC) OFF until Deliver the last sheet of paper. Also clean rotation) the Main Motor stops. the Transfer Roller. If another PRNT signal is sent from the Formatter, the printer returns to the INTR period. If not, it returns to the STBY period. 5-28 Functional Overview