Paper Up Drive Control - Minolta Di850 Service Manual

TRAY 3 PAPER FEED UNIT

[4] Paper Up Drive Control

5VDC
PS16
PS16
SGND
PS22
PS22
PS40 PS40
24VDC
M21
M21 CONT
24VDC
SD7
SD7 CONT
Papers stacked in the tray are pushed up by transmit-
ting the drive force of M21 (up drive 3) to the paper up/
down plate in the tray via up/down wires. MC21 is con-
trolled directly by PRCB (printer control board). The
related signals are PS22 (tray upper limit 3) and PS40
(remaining paper detection 3). To prevent pull-out of
tray during copying operation that cause paper jam-
ming, a tray lock mechanism is implemented by PS16
(handle release 3) and SD7 (lock SD3).
1. Operation
a. Paper up drive control
When tray 3 is loaded, M21 goes ON for a fixed
time, raising the paper up/down plate in the tray.
When PS22 detects the upper limit of paper as
the paper up/down plate in the tray goes up, it
goes ON and consequently M21 goes OFF, stop-
ping raising the paper up/down plate. When
PS22 goes OFF after a paper is fed, M21 goes
ON again, moving the paper up/down plate
upward. The paper up/down plate in the tray is
lowered mechanically by its own weight.
b. Paper up drive timing
(1) ON timing
M21 is turned ON when loading of a tray is
detected (by shorting wires at both ends of the
drawer connector) or when no paper is detected.
(2) OFF timing
M21 is turned OFF when PS22 is turned ON.
5VDC
SGND
DCPS1
24VDC
PGND
24VDC
PGND
DCPS2
PRCB
c. Remaining Paper Detection
The level of paper remaining in each tray is
detected according to the time that M21 requires
to lift up the paper up/down plate when the tray is
set. This lift-up time (operation time of M21) is
recorded in the PRCB. Subsequently, remaining
paper is detected by the paper feed counter. The
detected remaining paper level is displayed on
the operation panel in 5 steps. PS40 is used to
detect the remaining paper level when it drops
below about 10%.
d. Tray lock control
When the tray handle is gripped, PS16 is turned
ON. This signal then causes SD7 to go ON,
releasing the lock.
2. Signals
a. PRCB input signals
(1) PS16 (PS16 to PRCB)
Tray drawer handle detection signal.
[L]: Detected
[H]: Not detected
(2) PS22 (PS22 to PRCB)
Paper upper limit detection signal.
[L]: Not detected
[H]: Detected
(3) PS40 (PS40 to PRCB)
Remaining paper detection signal.
[L]: Detected
[H]: Not detected
b. PRCB output signals
(1) M21 CONT (PRCB to M21)
M21 ON/OFF control signal.
[L]: M21 ON
[H]: M21 OFF
(2) SD7 CONT (PRCB to SD7)
SD7 drive control signal.
[L]: SD7 ON
[H]: SD7 OFF
2-K-4