Optical System - Sharp SF-2314 Service Manual

5. Optical system

5-1. General descriptions
•
The optical system is composed of the fixed focus lens and six
mirrors.
Since the fixed focus lens is employed, No.4/No. 5 mirror base is
moved as well as the lens to change the distance between the
document and the drum (OID, Original Image Distance) for reduc-
tion and enlargement.
To move the lens and No.4/No. 5 mirror unit, he stepping motor is
driven by the signal from the main control PWB to allow zooming
of 0.70 to 1.22 (inch series: 0.64 ∼ 1.29) with 1% increment. (The
SF-2314 has no zooming function, and its lens and No.4/No.5
mirror base are fixed.)
1
Copy lamp
4 No. 2 mirror
7
No. 4 mirror
F No. 2/No. 3 mirror base unit
I Mirror motor
L
Mirror home position sensor
(1) Original table
The original table is fixed, and originals are set to the left frame side
as the reference.
16
4
15
5
10
2
Reflector
5 No. 3 mirror
8
No. 5 mirror
G Copy lamp unit
J Lens/No. 4/No.5 mirror base drive motor
M
Auto exposure sensor
•
Exposure is adjusted by changing the voltage of the copy lamp.
The copy lamp unit is provided with the AE sensor for detection of
the original density to adjust the light quantity of the copy lamp
according to the original density.
•
For exposure, the slit exposure system is employed where the light
source is moved. (The original table is fixed.)
2 1
3 11
9 17 6
(2) Copy lamp
100V system (285W)
200V system (285W)
(3) Mirror
Six mirrors are used.
No. 1 mirror is provided in the copy lamp, No. 2/3 mirrors at the
No.2/3 mirror base, No. 4/5 mirrors at the No. 4/5 mirror base. The
No.2/3 mirror base is scanned during copying. The No.4/5 mirror
base is moved to change the distance between the original and the
photoconductor during zoom copying.
(4) Lens (Fixed focus lens)
•
Construction (One group 3 lenses)
•
Brightness (F8)
•
Focus (175mm)
(5) Lens home position sensor (LHPS)
This sensor is used to sense the lens position. The sensor output
signal serves as the basic signal to control the copy magnification
ratio.
(6) Lens base
The lens is mounted to this lens base. It is moved in the paper feed
direction in reduction copying, and in the paper exit direction in enlar-
gement copying.
5 – 3
7 12 13
8 14
3
No. 1 mirror
6 Lens
9
No. 6 mirror
H No. 4/No. 5 mirror base unit
K Lens home position sensor