MX-M950, MX-MM1100 (serv.man18). Details of Each Section - F Paper Transport Section - Sharp Copying Equipment Service Manual (repair manual). Page 4

MX-M1100  PAPER TRANSPORT SECTION  F – 4

The sensor is composed of ultrasonic generator part and ultrasonic
detector part.  Double feed is detected using 220kHz ultrasound.
Operation when sheets of paper are normally fed one by one
Some of the ultrasound is reflected by the paper, but the ultrasound
reaches the sensor more than the specified level.
The sensor analog output level at that time is 300mV or more, and
digital output level is "L."
Operation when double feed occurs
Most of ultrasound is reflected when double feed occurs, because
the stiffness of paper is high.  As a result, the ultrasound which
reaches the sensor is weak, and less than the specified level.
At that time, the sensor analog output level is 300mV or less, the
digital output level is "H."

1)

Pull out the tray 1, 2 (a).

2)

Remove the screw (a), and remove the tray 1, 2 (b).

3)

Open the front cover (a), and pull out the intermediate frame
(b).

4)

Disconnect the connector (a), and remove the screw (b).
Remove the paper pass unit (c).

Paper pass unit

A

Cassette 1 paper entry detection

F - 5/a

B

Cassette 1 transport detection 1

C

Cassette 1 transport detection 2

Ultrasonic sensor

(DFS PWB)

Ultrasound
generate

Digital signal
output

PCU

PWB

Ultrasonic

generator

Amplifier

Detection
circuit

C

B

A

a

a

a

b

a

a

b

b

b

c

a