KERN & SOHN VFS 2T1 Addendum - Manual (Page 16)

EPM205 - Technical reference - Rev. A Page 16
Advanced Printing Systems
6. SENSORS
6.1. Door open
In order to optimize and decrease the number of elements of the EPM, the opto sensor performs dual
functions - door open and end of paper detection. The shape and distance from the opto sensor to the paper
is designed in a way that as soon as the door is opened, the distance between the paper and the sensor
increases, and this causes the end of paper sensor to trigger.
6.2. End of paper sensor
The EPM205 has an end of paper sensor achieved by a photo-transistor. Arrange the circuitry so that no
energy is applied to the head when there is no paper. If the head is energized when there is no paper and the
head is in the down position, then both roller and head may be strongly damaged.
OPTO characteristics:
Item Symbol Conditions Min. Typ. Max. Unit
Forward voltage
(photodiode) V
F
I
F
= 10mA - - 1.3 V
Reverse current I
R
V
r
= 5V - - 10 mA
Output dark current I
CEO
V
CE
= 10V - - 0.2 mA
Light current I
L
V
CE
= 5V
I
F
= 10mA
180 - 440 mA
Rise time T
R
V
CE
= 2V
I
C
= 0.1 mA
R
L
= 1KΩ
- 30 - ms
Fall time T
F
- 25 - ms
One possible interfacing is as follows:
180 27K
+5V +5V
VOUT
VOUT > 3.5V ---> No Paper
VOUT < 2.5V ---> Paper
ELM244 SIDE
USER SIDE
(To analog input)