Panasonic DP-CL18 Technical Manual page 24

DP-CL18
3.5.4. High Voltage Board Circuit
This board outputs 12 high voltages used for electronic photographic process. The 12 voltages consists of 2 charge (VCH/YMC,
VCH/K: DC-1,000 ~ -1,400V) for color (YMC) OPC and black OPC, 4 development bias (VB/Y, VB/M, VB/C, VB/K: DC-100 ~ -300V
+ AC400V ) for each color, 4 supply bias (VSR/Y, VSR/M, VSR/C, VSR/K: -200 ~ -300V), FTR bias (FTR: 250 ~ 1,800V), STR
p-p
bias (STR: -500 ~ 6,200V). The Charge, Development bias, FTR Bias and STR Bias voltages are varied by the D/A converter
setting data from the engine control board. If the signal DNHVEN is a low, 2 Charge, 4 Development Bias, 4 Supply Bias, FTR Bias
and STR Bias voltages are generated. Each of the high voltages are specifically set depending on the print media, selected
resolution, printing mode, duplicate mode and humidity/temperature range of the room. The humidity and temperature are detected
by a humidity sensor.
1. Charge Control Circuit :
This circuit consists of a DC-DC converter, which boosts +24V to approximately -1,000 ~ -1,400V for the charge bias (maximum
current rating 50µA for each color). This circuit has 2 boost circuits (VCH/YMC: Color, VCH/K: Black). The VCH/YMC and
VCH/K voltages are controlled individually by the D/A converter circuit on the high voltage board.
2. Development Bias Control Circuit :
This circuits of a DC-DC converter and a DC-AC converter. The DC-DC converter boosts +24V to approximately -100 ~ -300V
for the development bias (maximum current rating 150µA). The DC-AC converter adds the rectangular AC voltage to
development bias. AC frequency value is approximately 800/1000 Hz that is determined by the external clock signal HVACCLK
from IC14 (ASIC) on the engine control board. The development bias control circuit has 4 boost circuits (VB/Y: yellow
development bias, VB/M: magenta development bias, VB/C: cyan development bias, VB/K: black development bias). The VB/Y,
VB/M, VB/C and VB/K development bias voltages are controlled individually by the D/A converter circuit on the high voltage
board.
3. Toner Supply Bias Control Circuit :
This circuit is coupled with the development bias control circuit, which outputs 4 toner supply bias voltages (VSR/Y: yellow color,
VSR/M: magenta color, VSR/C: cyan color, VSR/K: black color). The voltage value is approximately -200 ~ -400V (lower than
the development DC bias value).
4. First Transfer Control Circuit ( FTR ) :
This circuit consists of a DC-DC converter, which boosts +24V to approximately 250 ~ 1,800V for the first transfer bias
(maximum current rating 80µA). This voltage values is controlled by the D/A converter circuit on the high voltage board.
5. Second Transfer Control Circuit ( STR ) :
This constant current circuit generates approximately 1.5 ~ 100µA for the second transfer bias. This current values is controlled
by the D/A converter circuit on the high voltage board.
6. Reverse Bias Control Circuit :
The high voltage board has 3 reverse bias control circuits : Development Bias VB(+), Toner Supply Bias VSR(+), Second
Transfer Bias STR(-).
VB(+) [ approximately 170V ] is generated from the charge bias voltage VCH/YMC by the coupling Zener diode on the high
voltage board.
VSR(+) is coupled with the development reverse bias VB(+).
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