Brother DCP 385C - Color Inkjet - All-in-One, Service Manual

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3-41 Confidential
Other controls
Paper feed position and speed control
A PF encoder disk with the resolution of 300 dpi (0.084 mm pitch) is mounted on the PF roller
gear L. The PF encoder sensor uses it to generate a signal indicating the gear rotation speed--in
other words, the paper feed roller speed--to the controller for use in controlling paper feed
position and speed.
Paper stop position control
The controller uses the PF encoder signal for proportional, integration, differential (PID)
control of the paper feed motor to produce high-resolution precision paper positioning during
printing. This signal also determines the motor parameters for rapidly and precisely positioning
the paper.
Fixed-speed paper feed
This operation rotates the paper feed roller to feed the paper at a constant speed regardless of
load fluctuations. The primary application is ejecting paper when printing is complete--in other
words, in situations where precision stop position control is not needed.
Paper feeding amount control
There is variation in the head nozzle pitch of individual head/carriage units, as well as in the
shape of the paper feed and ejection rollers. To make those parts match each other, therefore,
updating the paper feeding correction value (Function code 58) is necessary (see
Chapter 9,
Section 9.1.4.18 ).