Canon LASER CLASS 730i, Service Manual

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LASER CLASS 730i/720i/710 Chapter 2: Technical Reference
2-16
4.2 Toner Cartridge
This cartridge comprises the primary charging roller, developing cylinder, photosensitive drum,
cleaner blade, and toner.
The Laser beam from the Laser/scanner section forms a latent static image on the photosensitive
drum that is charged by the primary charging roller.
The photosensitive drum rotates inside the toner cartridge, and rotation of the developing
cylinder causes toner to adhere to the photosensitive drum to from a visible image which is then
transferred to the recording paper at the toner transfer section. Residual toner is then removed
from the surface of the photosensitive drum by the cleaning blade.
4.2.1 Toner level detection/cartridge detection
The FX 7 toner cartridge has a toner sensor.
The circuit compares the output value of the developing AC bias and the output value (ANT)
from the antenna inside the cartridge, and outputs the toner detection signal.
The CPU detects the toner level and whether the cartridge is installed or not when the
developing AC bias is applied to the developing cylinder. The toner level is always detected
when the developing AC bias is applied, and the cartridge is detected only when the
developing AC bias is applied during the initial rotation.
Drum cover shutter
If the photosensitive drum is subjected to strong light, optical memory can
cause dropout areas or black bands to occur. To prevent the photosensitive
drum from strong light, a drum cover shutter is attached. Do not open this
cover unless absolutely necessary.
4.3 Toner Transfer Section
This section comprises the transfer charging roller and the static eliminator.
The recording paper passes between the photosensitive drum and the transfer charging roller,
and the transfer charging roller is charged with a charge opposite to that of the toner to transfer
the toner on the photosensitive drum to the recording paper. The charge on the rear side of the
recording paper is then removed by the static eliminator.
4.4 Fixing Section
This section comprises the fixing ass’y and pressure roller. The fixing section on this machine is
an on-demand method that uses fixing film with low thermal capacity.
The toner that was transferred to the recording paper at the toner transfer section is fused to the
paper and fixed as a permanent image.
The fixing ass’y has a built-in fixing heater and thermistor.