SHARP SP1536 Technical Report

Date: Jan. 29, 1993

COPIER : SF-7370

No. : SP-1536

PREVENTING COPY IMAGE DISTORTION
BY MOISTURE CONDENSATION

1.Model name: 6514/6413

2.General: Owing to installed machine location and the use of dampened paper, a distortion may

appear in a copy image caused by water evaporated when the copy paper goes
through the fusing unit. To avoid this, the following change is made in order to change
the air flow within the machine.

3.Phenomenon: Bleeding may appear towards the copy moving direction in the multicopy mode.

In case of a
vertical line.

Copy moving direction

4.Cause: Distortion may appear in the image when the following conditions are met together.
(1) The machine is tried to make copy when the machine internal temperature is

different from the room temperature for about 8 °C as the machine was left unused

under a cold temperature for a long time or the machine internal is cold in night time.
(2) Use of a moistened paper.
(3) Where there is a relatively high humidity existing in the room the machine installed.

In case of the
character “ ”

If copies were made in the multicopy mode under the above conditions, water vapor
from the fuser unit attacks the main motor area through five holes (φ8) of the motor
baseplate of the paper entry side of the fuser unit as carried along by the main motor

SHARP CORPORATION Reprography Division

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Green

C

fan and is condensed on the drum, resulting in the circulation of dampened air around
the area. As more copies are produced, more moistures appear around the drum and
condenses on the drum. Consequently, the condensed moisture is collected by the DV
plate of the DV cover, thus causing the electric charge collected on the drum flows
through the water (short). This distorts the image causing distortion to appear on the
copy.

4.Description: (1) Block holes in the motor baseplate.
(View of the motor baseplate from below with the machine left open)

Front frame side

Transport guides

Shadowed area

φ8
These five 5 holes are clogged by the use of a new press mold.

(2) Square holes added to the fuser cover

(To release the air within the fuser unit to the rear.)

Square holes provided new

Rear frame side

Fuser cover

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The new fuser cover pasted with the high temperature caution label and the guide mylar
T will be in supply.