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REV.-A
2.4.2.3 Revolution Control
There are five basic motor revolution speeds (carriage speeds), each of which will operate in print speed,
accelerated speed, or reduced speed mode. The speed setting is provided in the form of speed data;
pulses from the standard data clock are counted; and the relevant frequency is provided to the control
circuit. Revolution speed control is performed in accordance with the comparison, by the encoder, of
this frequency with the pulse count that the encoder detects. In accordance with the speed selected,
the speed control method is either phase-locked loop (PLL) or period control (PRC).
Table 2-4. Carriage speeds
Mode No.
Set speed (kHz)
Set frequency (115)
Control type
Print density (OPI)
3
2.97
337
PLL
360
2
4.45
225
240
1
5.94
168
PRC
180
0
8.91
112
120
The set speeds shown above are the basic speed modes; i.e., the speeds which normally apply during
printing. "Accelerated speed" or "reduced speed" modes are applied to these standard speeds on a
line-by-line basis. This application is effected by supplying the necessary additional data to the DCU.
The clock used for this operation is provided by external oscillator CRI, with connects to DCU (4B)
terminals XIN and XOUT.
If there are problems with this oscillator or its connection to the DCU, therefore, the carriage will
completely fail to operate. The oscillation frequency is 614.4kHz.
2-45
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