Epson DLQ-3000+, Service Manual

Page: 91 / 262

Operating Principles
Rev. A
2-29
2.3.11 Paper Jam Sensor
This printer is equipped with the paper jam sensor mechanism which consists of the
magnetized roller attached to the same shaft for the sub loading roller assembly and the
sensor (hall element) located beside the rear paper sensor. Having no contact with the
loading drive roller assembly, the magnetized roller rotates independently along paper. Table
2-20 shows the paper jam sensor specification.
Table 2-20. Paper Jam Specification
Detecting element Hall element
Outputs In 1 channel, TTL level
Power supply voltage
5 VDC 5%
P A 7
P a p e r F e e d D r i v e R o l l e r A s s e m b l y
P a p e r
P a p e r J a m S e n s o r
( H a l l S e n s o r )
P J A M
M a g n e t i z e d R o l l e r
C P U
Figure 2-23. Paper Jam Sensor Block Diagram
The CPU reads the signal output directly from the paper jam sensor for each step (1/216
inch / step). If the current signal condition is the same as the previous one, it indicates the
status that the magnetized roller is not rotating, which is considered paper jam. When the
printer detects that condition continuously for the specified numbers of the output signals, it
indicates the paper jam error, and enters non-printing status. The paper jam signal
conditions for normal state and paper jam state are shown in Figure 2-24.
C u r r e n t l y d e t e c t e d c o n d i t i o n
P r e v i o u s l y d e t e c t e d c o n d i t i o n
N o r m a l P a p e r F e e d i n g C o n d i t i o n
P a p e r J a m C o n d i t i o n
Figure 2-24. Paper Jam Sensor Signals
Paper jam detection starts after each paper loading motion regardless of the paper feed
direction. However, the sensor ignores the pulse output while the paper feed direction is
changed.