5 ] Operating Principle - Sharp AR-LC1 Service Manual

[5] OPERATING PRINCIPLE
1. Lift-up operation
When the copier is powered up, the main circuit checks the detection
state of each sensor. If the upper limit detector (LUD) is OFF, the
lift-up motor is turned on to elevate the tray till the position which
allows paper feed (upper limit detector ON).
1 Upper limit detector (LUD)
2 Paper detector (LPED)
3 Paper tray
4 Lower limit detector (LDD)
Lifting (no paper, lifting from bottom to top)
Elevation starts
LLMD
LLMU
LDD
About 100 msec
LUD
2. Lift-down operation
If no paper is present after paper feed, the main circuit detects the
ON condition of the paper detector (LPED) and turns on the lift-up
motor to descend the tray till the position at which the lower limit
detector (LDD) turns on (the tray can be drawn out).
The tray switch PWB indication LED blinks while the tray is lifting or
descending.
Lifting (no paper, descending from top to bottom)
Descending starts
LLMD
LLMU
LDD
LUD
3. Paper feeding
When copying is started, the transport motor (LPFM) starts. Then, the
1,2
pick-up solenoid (LPFS) and paper feed clutch (LPFC) turn on. When
the solenoid is turned on, the paper hitching roller is lowered to
contact the paper.
When the clutch is turned on, both the paper feed roller and the
hitching roller rotate to start paper feeding. The paper is sent through
3
the transport sensor (D) to the copier.
4
Reversion starts
5msec
30msec
1
2
3
4
Paper feed (Letter size, A4, B5)
Job start signal reception
LPFM
LPFC
LPFS
LPFD
5 – 1
30msec
2
1
2
3
Paper feed roller clutch (LPFC)
Paper hitching roller
Paper feed roller
Pick-up solenoid (LPFS)
Paper feed start signal reception
100msec
4
3
4
Paper feed finish
signal transmission
Job END signal
reception