e-STUDIO170F Circuit Description
January 2005 © TOSHIBA TEC
7 - 28
7.3.4
Fuser Control Circuit
Fig.7-22
The fuser control circuit consists of the Engine-CPU (IC37) as the central component. It calculates fixity
according to the temperature information detected by the thermistor to control the heater lamp built in
the fuser.
The Engine-CPU converts the THERMISTOR signal output from the thermistor from analog to digital.
Then, it compares the converted measured value with the predetermined value stored in the internal
register. If the measured value is lower than the predetermined value as a result of the comparison, the
Engine-CPU makes the P17 signal HIGH level and turns Q107 OFF. This turns Q105 ON and the
HTON1X signal to LOW level. This allows the heater drive circuit of the LVPS to supply AC power to the
heater lamp to increase the fixing temperature.
For the heater drive circuit, refer to
P.7-74 "7.6.4 Heater Drive Circuit" in this chapter.
If the measured value is higher than the predetermined one, it causes the HTON1X signal to go HIGH
to cut off the power supply to the heater lamp and lowers the fixing temperature. If the measured value
is calculated as an abnormally high or low temperature the HTON1X signal is kept at HIGH to turn off
the heater lamp until the abnormal state is cleared.
Also, the voltage of the THERMISTOR signal is compared with the reference voltage on the electrical
circuit by the operational amplifier. If the Fuser temperature rises abnormally for some reason, the volt-
age of the THERMISTOR signal becomes lower than the reference voltage and Q106 is turned ON.
This turns Q105 OFF regardless of the status of the P17 signal, turns the HTONX1 signal to HIGH level
and turns the heater lamp OFF. Moreover, this turns Q101 OFF on the circuit of another route, and
makes the HTON2X signal HIGH level to cut off the power supply to the heater lamp.
After a fixed time elapses while the machine is in the standby state with the printer power saving func-
tion setting ON, the Engine-CPU causes the HTON1X signal to go HIGH to cut off the power supply to
the heater lamp, thereby controlling power consumption.
IC37
Engine-CPU
Main PBA
Fuser
71
HTON1X
HTON2X
1
4
2
2
3
1
2
3
THERMISTOR
P17
87
1
2
8
9
CN1
CN2
Heater lamp
Thermistor
Q105
IC28
Q101
Q106
Q107
LVPS
-
+
+5V1
R230
IC36
IC35
R231
+5V1
+5V1
+5V1
+5V1
+5V1
CN18
CN17
Содержание ESTUDIO170F
Страница 1: ...SERVICE MANUAL PLAIN PAPER FACSIMILE e STUDIO170F File No SME04002900 R04102171300 TTEC Ver01_2005 05 ...
Страница 2: ... 2005 TOSHIBA TEC CORPORATION All rights reserved ...
Страница 192: ...e STUDIO170F Function Settings January 2005 TOSHIBA TEC 4 132 ...
Страница 214: ...e STUDIO170F Mechanical Description January 2005 TOSHIBA TEC 5 22 ...
Страница 308: ...e STUDIO170F Circuit Description January 2005 TOSHIBA TEC 7 78 ...
Страница 372: ...e STUDIO170F Removal Replacement Adjustment January 2005 TOSHIBA TEC 8 64 ...
Страница 490: ...e STUDIO170F Appendix January 2005 TOSHIBA TEC 12 8 ...
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