Canon LBP-1000, Service Manual

Page: 33 / 178

CHAPTER 2
OPERATION AND TIMING
1. This chapter describes the printer functions, the relationships between mechanisms and cir-
cuits, and the timing of operations. Mechanical linkages are indicated by black and white
lines ( ), the flow of control signals by solid arrows ( ), and the flow of groups
of signals by outline arrows ( ).
2. An active-high signal is indicated by "H" or by a signal name without a slash in front of it,
such as "PSNS." An active-low signal is indicated by "L" or by a signal name with a slash in
front of, such as "/SCNON."
A signal that is "H" or has a name without a slash is active at the supply voltage level
(indicating that the signal is being output), and inactive at ground level (indicating that the
signal is not being output).
A signal that is "L" or has a slash in front of its name is active at ground level, and inac-
tive at the supply voltage level.
There is a microcomputer in this printer. But as the internal operation of the microcom-
puter cannot be checked, an explanation of the operation of the microcomputer has been left
out.
As it is assumed that no repair will be made to customer circuit boards, the explanation
of board circuits is limited to an outline using block diagrams. So there are two types of cir-
cuit explanations; (1) everything from the sensor to the input sections of the major circuit
boards, (2) everything from the output sections of the major circuit boards to the loads.
These are explained with block diagrams according to the function.
I. BASIC OPERATION ................... 2-1
II. ENGINE CONTROL SYSTEM ...... 2-4
III. LASER/SCANNER SYSTEM ....... 2-18
IV. IMAGE FORMATION SYSTEM.... 2-24
V. PICK-UP/FEED SYSTEM ........... 2-32
VI. VIDEO CONTROL SYSTEM ........ 2-38
VI. PAPER FEEDER ........................ 2-47