Brother International HL 1240 Service Manual - Page 57

CHAPTER 3 THEORY OF OPERATION 2.2 Paper Transfer 2.2.1 Paper supply The paper pick-up roller picks up one sheet of paper from the paper cassette every time it is rotated and feeds it to the paper feed roller. Pinch roller Paper feed roller Paper pick-up roller Front registration sensor lever Pinch roller Pressure plate Separation pad Fig. 3-23 The paper is gripped between the paper pick-up roller and the separation pad and separated into individual sheets. The pick-up roller is directly connected to the clutch mechanism, whose rotation is stopped by the stopper arm. When the pick-up solenoid is activated, the clutch mechanism is engaged by the solenoid action and the paper pick-up roller is driven. The paper drawn out of the tray by the pick-up roller pushes against the front registration sensor lever and the paper top position/absence of paper is detected by sensing the motion of the lever. 2.2.2 Paper registration After the paper top position is detected by the front registration sensor, the paper, separated into individual sheets by the paper pick-up roller, is fed further for a specified time, and the paper top position reaches the paper feed roller so that the paper skew is adjusted. Then, the solenoid is turned off, the paper feed roller starts turning, and the paper is fed to the transfer block in the drum unit. Photosensitive drum Paper feed roller Transfer roller Rear registration sensor lever Fig. 3-24 The rear registration sensor in the path from the feed roller to the transfer roller controls the first print position on the paper. 3-19