Technical information

E. Controlling the Development
Bias
1. Outline
Figure 3-28 shows the circuit that controls the
development bias and has the following functions:
0 Tums the development bias AC component ON
and OFF.
Q Controls the development bias DC component
voltage level.
The copier varies the voltage level of the develop-
mentbiastocontrolthecopydensityaccordingtothe
settings of the following:
- Copy density key position
- AE sensor output
- Developing assembly type
When the black developing assembly is set. J24-1
and -4 are shorted by means of a jumper wire,
thereby identifying the presente of the assembly.
2. Mechanism
a. Tuming the Development Bias AC Component
ON and OFF
The square wave osciilatorcircuit is at work at all
times as long as power is present.
@ When ACBON=l,
4AC bias switch circuit goes ON.
bsquare wave oscillator circuit output is
cut.
The above condition deprives the developing
cylinder of AC biases.
Q When ACBON=O,
bAC bias switch circuit goes OFF.
The above condition causes the AC bias switch
circuit to go OFF; as such, the output of the
square wave oscillator is sent to the Tl drive
circuit. raised lo 1300 VAC, and is supplied lo the
developing cylinder. The output of the AC high-
voltage transformer, on the other hand, is recti-
fied by the rectifier circuit and supplied to the
static eliminator (about 3.2 KV).
3-30
COPYAIGHT 0 1992 CANON ING. CANON NP2lZO/ZGZO RN.0 MAY 1990 PNINTED IN JARN IMPRIME AU JAPONI