Lexmark T652 Service Manual - Page 299

4062-XXX The pick arm assembly (autocompensator) is a paper pick device that generates its own normal force. This force generation is inherent in the fundamental design of the pick arm. If light media is used, it picks very gently. If a heavy media is used, it picks very aggressively. No customer adjustments are necessary, therefore no special trays are needed for card stock or labels. The gearing in the arm is designed so the input torque from the motor produces a movement about the pivot of the arm. This movement produces a downward force at the pick rolls. The friction between the pick roll and the paper produces a frictional locking condition. If the paper is physically held and not allowed to feed, then the motor stalls. Slippage between the roll and the paper is theoretically impossible. When the motor is energized, the pick rolls are driven down into the stack, increasing the normal force and drive force until the bending strength of the paper is overcome and the paper bends and moves up the wear strip. Switch (media size) This switch (media size) sets the size of media supplied from each media tray assembly. A signal indicating the media size is transmitted as a voltage to the printer system card assembly. Sensor (media empty) If media runs out in a media tray assembly, the actuator lowers and the actuator flag, unlocks the sensing area of the sensor (media empty). The sensor light is transmitted. When the sensing area is blocked (media is present), the signal is off. Sensor (media low) This sensor detects by the actuator position whether media in the media tray assembly is low. When the flag of the actuator blocks, then unblocks the sensing area of the sensor (media low), the media level is determined to be low Sensor (pass-thru) A photointerrupter sensor with a built-in flag that sends a signal to the engine where the media from the input tray passes. This will trigger the pick arm to pick the next media. Pick arm assembly Sensor (media empty) Sensor (media low) 250-sheet drawer assembly Sensor (pass through) Diagnostic aids 3-87