Pickup/Feeding; Operation - Canon LBP-2000 Service Manual

C. Pickup/Feeding

Operation

1 . O u t l i n e
The paper feeder pickup motor is a stepping motor, and its speed is controlled by the paper feeder
controller PCB.
The paper feeder controller executes pickup operation or feeding operation in response to the
pickup command or the feed command from the DC controller of the Printer.
In response to the pickup command, the paper feeder controller PCB drives the paper feeder
pickup motor (M201) at high speed. The paper feeder pickup clutch (CL201) goes on at the same
time, causing the paper feeder pick up roller to rotate to pick up paper from inside the cassette of
the paper feeder.
The cassette separation pad makes sure that only a single sheet of paper is picked up, and the
paper is moved by the feeding roller to the Printer or the next paper feeder in the paper path.
A specific period of time thereafter, the paper feeder controller PCB switches the speed of the
paper feeder pickup motor so that it is the same as that of the Printer. The feeding roller as a result
will start to rotate at the same speed as the Printer to move the paper.
If pickup occurs from the bottommost paper feeder as when multiple paper feeders are in-
stalled, the top paper feeder will be part of the paper path, requiring its feeding roller to rotate.
When the feed command is revised, the paper feeder controller PCB rotates the paper feeder
pick up motor at high speed so that the feeding roller rotates to move the paper to the Printer. A
specific period of time thereafter, the paper feeder controller PCB switches the speed of the paper
feeder pickup motor to the speed of the Printer so that the feeding roller will start to rotate at the
speed of the Printer to move the paper.
The paper path is equipped with a single photointerrupter used to monitor the arrival or pas-
sage of paper.
If paper fails to reach the sensor within a specific period of time or fails to move past it, the
microprocessor (CPU) on the DC controller PCB of the Printer will identify the condition as indicat-
ing the presence of a jam, and will communicate the fact to the video controller.
The size of the cassette or the presence/absence of the cassette is detected as in the case of the
Printer itself. (See V-B 'Detecting the Paper Size' in Chapter 2.)
The position of each cassette, on the other hand, is identified with reference to the machine
inside communication signal (/TXDOU) and the options select signal (/STERMU), which are the
input signals from the Printer's DC controller.
The Printer's DC controller sends the inside machine communication signal (/RXDOU) to find
out the position of cassettes in relation to the number of options select signal (/STERMU), which
is an output signal from the paper feeder controller PCB.
CHAPTER 2
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