2 - 11
CHAPTER 2
2. Operation
a. Primary Charging Roller Voltage Generation
When the pickup command is sent from the interface controller, the INITIAL ROTATION period (INTR) starts, and the
PRIMARY HIGH VOLTAGE (AC) DRIVE signal (PRACC) is input to the primary high-voltage circuit via the power
operational amplifier. Meanwhile, the PRIMARY HIGH-VOLTAGE (DC) DRIVE signal (PRDCC) is output from the
CPU and input to the primary high-voltage circuit. This generates and combines AC bias and DC bias. The combined
primary high-voltage is applied to the primary charging roller.
The IC302 compares the primary high-voltage (DC) with the PRIMARY HIGH-VOLTAGE (DC) DRIVE signal
(PRDCC) sent from the CPU in order to control the primary high voltage (DC).
The presence of the cartridge is detected by the CPU. If the CPU detects the current flow (CRGSNS) on the J304,
it determines the presence of the cartridge.
b. Developing Bias Generation
The DEVELOPING BIAS (AC) DRIVE signal (DVACC) is input to the developing bias circuit via the power operational
amplifier, causing the circuit to generate the AC bias. Meanwhile, the developing DC bias is generated in the DC
generation circuit on the developing bias circuit. The AC bias and DC bias are combined and applied to the developing
cylinder.
c. Transfer Charging Roller Voltage Generation
The transfer charging roller is applied with the negative bias, print bias, and between-page bias according to the print
sequence.
The negative bias (negative voltage) cleans the roller by moving the toner adhering to the roller to the photosensitive
drum. A negative voltage is applied to the roller at the specified timing.
The print bias (positive voltage) transfers the toner on the photosensitive drum onto the paper. A voltage is applied
to the roller.
The between-page bias prevents the residual toner on the photosensitive drum from adhering to the transfer charging
roller. A positive voltage lower than the print bias is applied to the roller at the specified timing.
When the interface controller outputs a pickup command, the INITIAL ROTATION period (INTR) starts. At the
same time, the CPU outputs the TRANSFER NEGATIVE VOLTAGE DRIVE signal (TRNFOT). This applies negative
bias to the transfer charging roller for the specified period of time as to clean the roller.
During the print sequence, the CPU outputs the TRANSFER POSITIVE VOLTAGE DRIVE signal (TRPWM) in
order to apply the print bias and between-page bias to the transfer roller.
After printing is completed, the negative bias is applied again to clean the transfer charging roller.
d. Fixing Bias Generation
The CPU outputs the PRIMARY HIGH-VOLTAGE (DC) DRIVE signal (PRDCC), causing the DC generation circuit
on the primary high-voltage circuit to output the primary DC bias. The negative DC voltage is applied to the pressure
roller as the fixing bias.
e. Cartridge Detection
When the PRIMARY HIGH-VOLTAGE (AC) DRIVE signal (PRACC) is output from the CPU and then the primary
AC bias is output from the AC generation circuit on the primary high-voltage circuit, the primary high-voltage circuit
feeds back the CARTRIDGE DETECTION signal (CRGSNS) to the CPU.
During WAIT period, the CPU checks the voltage of the CRGSNS signal at the timing the primary AC bias is output,
in order to detect the presence or absence of the cartridge.
Summary of Contents for Laser Shot LBP-1120
Page 4: ...PREFACE P 2 ...
Page 54: ...2 35 CHAPTER 2 Figure 2 6 1 4 1 3 2 J1 2 1 20 19 J2 IC2 IC1 IC3 IC4 ...
Page 107: ...APPENDIX A 2 ...
