Canon fax basic 2000 サービスマニュアル
GLOSSARY
A–68
DMA (Direct Memory Access)
Transfer
A system internal function, transfer of data
groups (memory blocks) that does not pass
through the CPU. DMA transfer can speed
up system performance as it does not place
a load on the CPU.
Document length
The length of the document in the vertical
scanning direction. The length of the docu-
ment in the horizontal scanning direction is
called the document width.
Double feeding
The state that occurs when two or more
sheets of recording paper loaded on the
paper cassette or tray or two or more docu-
ments placed on the copy board are fed at
the same time.
Driver IC
IC for driving motors, solenoids and other
components. Transistor arrays are often
used for the driver IC. When the driver IC
arrives, current is allowed to pass to supply
the current for driving components.
DTMF (Dual Tone Multi Frequency)
A signaling method that uses a combination
of two specific frequencies like that in push
button dialing.
Exchange
The equipment for connecting lines from
terminals and exchange stations.
Friction coefficient
The ratio between the friction force parallel
to a contacting surface acting on contacting
parts and the force acting perpendicularly
on a mutually contacting surface
Gamma characteristics
Gamma characteristics express the relation-
ship between input light intensity and out-
put voltage. When the output voltage is
proportional to the input light intensity, the
reproduction image quality will be good.
The image becomes distorted as this rela-
tionship is inverted.
Hamming distance
The number of different bits between two
signals of a determined bit length. The fol-
lowing shows an example for a 3-bit signal.
000 and 000: Distance 0
000 and 100: Distance 1
000 and 010: Distance 1
000 and 001: Distance 1
000 and 101: Distance 2
000 and 110: Distance 2
000 and 011: Distance 2
000 and 111: Distance 3
E
F
G
H
Good image quality
Distorted image
Input light intensity
Output voltage