Epson Stylus Photo 925, Руководство по обслуживанию

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EPSON Stylus Photo 925 Revision A
Operating Principles Electrical Circuit Operating Principles 45
V
Home Position Detection
The home position is detected based on the pulse output from the linear scale and
the DC motor drive current. The basic sequence for home position detection is as
follows:
1. The linear encoder pulse counter in the CPU is reset by initialization executed at
power on.
2. As the rotor of the CR Motor rotates in the normal direction (clockwise), the
carriage moves from left to right. When the following conditions are met, the CPU
supposes that the carriage has come in contact with the right frame:
T
The CPU has detected 720 mA as the CR motor drive current.
T
P1 (output pulse count during carriage operation) is 30
*1
or less.
3. As the rotor of the CR Motor rotates in the reverse direction (counterclockwise),
the carriage moves from right to left. When the following conditions are met, the
CPU suppose that the carriage has arrived at the lock lever position:
T
The CPU has detected 500 mA as the CR motor drive current.
T
The difference between P1 and P2 (output pulse count when the carriage
moves from the right frame) is 30.
4. The CR Motor reverses and the carriage moves from left to right again. If the CPU
has detected 720 mA as the CR motor drive current, the CPU supposes that the
carriage has come in contact with the right frame again.
5. The difference between P1 and P3 (output pulse count when the carriage moves
from the carriage lock lever to the right frame) becomes 4 or less.
When all the conditions in the sequence above are met, the printer judges that the
carriage is at the home position.
*1:
A specific value indicating that the carriage is at the home position (In this case,
the edges of all the pulses of the output waveform are monitored.)
V
PTS (Print Timing Signal)
The control circuit generates the PTS signal (cycles of 1/360 inch) from the phase
A subharmonic waveform.The print timing signal is used to discharge ink at
proper timing.
Figure 2-21. PTS and Phase A Pulse
Phase A
PTS