Paper Up Drive Control - Minolta Di551 Service Manual

[4] Paper Up Drive Control

Paper stacked in the tray is pushed up by trans-
mitting the drive force of M18 (tray up drive/3) to
the up/down plate in the tray via drive wires. M18
is controlled by the PRCB (printer control board).
Related signals are PS14 (tray upper limit/3) and
PS16 (remaining paper/3).
1. Operation
a. Paper up drive control
When tray 3 is loaded, M18 (tray up drive/3) turns
ON to lift the up/down plate in the tray. When
PS14 (tray upper limit/3) detects the upper limit
of paper as the paper up/down plate in the tray
goes up, it turns ON and consequently M18 goes
OFF, causing the tray to stop going up. When
PS14 turns OFF after paper is fed, M18 goes ON
again to move the paper up/down plate upward.
The up/down plate in the tray is lowered mechan-
ically by its own weight.
24V1
P.GND
5V2
S.GND
DCPS
T3RISEM_24
M18
T3RISEM_D
PRCB
2-K-5
TRAY 3 PAPER FEED UNIT
5V3
PS14
TIUP_PS
SGND
Tray 3
5V3
PS16
TIRM_PS
SGND
b. Paper up drive timing
(1) ON timing
M18 (tray up drive /3) is turned ON when loading
of a tray is detected. (by shorting wires at both
ends of the drawer connector)
(2) OFF timing
M18 (tray up drive/3) is turned OFF when PS14
(tray upper limit/3) is turned ON.
c. Remaining Paper Detection Control
The level of paper remaining in the tray is
detected according to the time that M18 (tray up
drive/3) requires to lift up the up/down plate when
the tray is set. This lift-up time (operation time of
M18) is saved in the PRCB (printer control
board). After this, the remaining paper is
detected using the paper feed counter. The
detected remaining paper level is displayed on
the operation panel in five steps. PS16 (remain-
ing paper/3) is used to detect the remaining
paper level when it lowers below about 10 %.