AM-300DE
b) Laser Drive circuit operation timing3.1.4 Fusing unit control
Laserdrivecircuit/LDDriveCircuitThe fusing section is heated by the heater lamp (500W). The heater
nHSYNClamp is controlled (turned on/off) to keep the optimum temperature.
The following signals are outputted by the CPU and Logic circuit for
nLDEN
control.
LaserOFFtime/LDOFFTime
3sfollowing/Lessthan3s1) Signal functionsnVIDEO
nS/H? HLON
This signal is to turn on/off the heater lamp. When this signal is
Laseroutput
outputted turn on triac TRA1. Then an AC power is supplied to
the heater lamp to turn on the heater lamp.
Settlingtime/SettlingTimeAPCcorrectiontime/AutoPowerControlTime
3msabove/Morethan3ms10sabove/Morethan10s
? RHT
Fig. 12This is the output signal of the thermistor which detects the sur-
c) Each signal injection timing of the scanner motorface temperature of the heat roller. It is inputted to the CPU. The
heater lamp is turned on/off depending on the value of RTH volt-
24Vage.
DC24V
0VMin10msMin10ms
2) Protect against overheat
H
IN
CLOCK
LThough the heater lamp ON signal (HLON-) is normal, if triac TRA1
Min0.1sMin0.1s
Hare kept ON, overheat may result.
nSTART
L
To prevent against this, temperature fuses are used.
Startingtime (Max0.5s)
UNLOCKWhen the fusing roller surface temperature exceeds about 214
Asynchronous
OUTnREADYdegrees C, the temperature fuse blows off to open the +24V power
LOCKMin1s
synchronousMin10ms
line which drives the power relay RL1, opening the power line for
UNCHECK
nREADYthe photo triac TRA1. Therefore, the power is not supplied to theCHECK
CHECK
Min1s
signalmonitoringheater lamp.
SpeedGO
Jitteretc.STOPA temperature fuse is also provided in the heater lamp power line.
In case of overheating, the heater lamp power line is opened
Fig. 13directly.
d) Laser Drive circuit interface3) Timing of temperature detection and heater control
Pin No. TerminalI/OFunctionAs shown by the following timings, four values of software ther-
mistor voltage are input as A/D conversion values. The mean value
4nLDENInputSignal enables Laser driven
of two medians among these four is regarded as the newest ther-
"H" : Disable
mistor value (temperature).
"L" : Enables
2nS/HInputAPC control signal? The value is compared with the temperature (200°C) control
"H" : Holdvalue every 100 ms.
"L" : Sampling
? If the value is higher than 200°C, the heater becomes OFF. If
3nVIDEOInputLaser control signallower, the heater becomes ON.
"H" : Laser OFF
? The heater ON timing is in accordance with the timing of Power
"L" : Laser ON
Zero Cross interrupt.
1GND-GND
5GND-GND
7GND-GNDHeater ON/OFF ControlHeater ON/OFF Control
6+5V-Power supply (+5V)
8nHSYNCOutputHorizontal synchronize signal
T (x 10ms)
(Open-"H" : Asynchronous
collector)"L" : Synchronous
Inputting thermistor values
Timings of thermistor value input and heater control
Fig. 14
4) Heater control (Temperature control)
Control method
a) Base machine printing (Copy, List, Receiving)
? Temperature control is started when data to be printed are
produced (or when slips are to be prepared).
? Temperature is controlled at 200°C. (Heater OFF over
200°C. Heater ON below 200°C.)
? After printing, temperature is not controlled. (Heater is not
turned ON.)
? Fan motor starts revolving from the beginning of temperature
control and stops 120 seconds after printing is finished.
5 - 15 |
ACEC
