Sharp FO-2970M Service Manual - Page 46

FO-2970MU 3) Unit control a. Main motor drive circuit This machine uses the 4-phase pulse motor, and is driven by the following pulses and the circuit 24VP 5V CNMMT MA 1 MA- 2 MM MB 3 MB- 4 IC2 14 VBB ENABLE1 ENABLE2 7 IC5 OUT1 OUT2 OUT3 OUT4 13 IN1 8 IN2 MA 116 MEN- 60 MB 137 (Drive waveform) ( Printer PWB) Stop Rotation ( Control PWB) MCA MCB MEN- Fig. 5 b. Paper feed controller Basically, the feed roller is rotated 1.5 times. If interval between PUS and PIN is within 0.5 sec., it is rotated 1 time. The procedure of clutch control 1 Timer is cleared by PUS ON according to clutch control demand. 2 PUS OFF 100 ms after PUS ON 3 1 PUS ON again 450 ms after the procedure above. 4 1 If paper is remained in PIN 500 ms after the procedure , the third 5 1 PUS ON is stopped. PUS OFF 1.25s after the procedure . Clutch control demand OFF if additional control is cancelled. 6 1 PUS ON again 1.534s after the procedure . 7 1 PUS OFF 2.334s after the procedure . 8 1 Clutch control demand OFF 3.366s after the procedure . If the paper is not fed normally and the paper in detector signal (PIN_) is not outputted even with the above operation, the PCU judges it as a paper jam display is made. The paper in detector signal (PIN_) is used for the top margin control signal in addition to jam detection. The diagram below shows timings of clutch operation. PUS 0.8 0.1 0.45 0.8 1.534 c. Electrical connection In the paper feed and transportation system, drive parts and sensors are connected as shown in the figure below. CONTROL PWB PRINTER PWB CPU (SH7041) 116 MA 60 MEN137 MB 13 7,14 8 1 IC2 17 Motor 4 driver 2 CNMMT 1 MA 2 MA3 MB 4 MB- ASIC (LR38784A) 130 PUS 142 PIN- 143 POUT- +24V 4 IC1 13 CNPL 1 +24V 2 PUS- +5V 1 3 4 PI2 PAPER IN SENSOR 2 +5V 1 3 PAPER OUT 4 PI1 SENSOR 2 132 PE CNLSU 9 PE MAIN MOTOR PAPER PICK-UP SOLENOID LSU PWB +24V CN601 9 PE PD601 CNPRT PAPER EMPTY SENSOR Fig. 7 • The main motor, which is the drive source for the paper feed and transportation system, is a 4-phase stepping motor in 2-phase excitement bipolar system, The step angle is 7.5°. • The pick-up solenoid operates on 24V to turn on/off paper feed. • There are following kinds of sensors. Paper empty sensor (Transmission photo transistor) : The paper empty sensor is positioned on the LSU PWB, and is used to detect presence of paper on the multi-purpose paper tray. Paper in sensor: (Transmission photo transistor): This sensor is used to detect the paper feed timing of the next paper (in prefeed) and to make synchronization between paper transport and image forming on the drum. This sensor is also used to detect paper jams. Paper out sensor: (Transmission photo transistor): This sensor senses paper exit, and paper jam. PIN 0.5 0.5 0.991 1.25 1.534 2.334 Fig. 6 3.366 5 - 10