Panasonic DP-CL18 Technical Manual page 38

DP-CL18
3.5.12. Toner Empty Sensor Circuit
This circuit has 4 toner empty detection circuits for cyan, magenta, yellow and black toner cartridges. These circuits are used for
detecting whether the toner is low ( or empty ) or if toner cartridge is installed or not.
<Yellow Toner Empty Detection Circuit>
The ASIC IC14 sends the pulse signal EMPLEDY from pin 202 of IC14 to the transistor Q10. When the signal EMPLEDY is a low
level, the transistor Q10 is turn on, turning on the LED D1504. This signal EMPLEDY is a pulse signal which causes LED D1504
to blink. If the toner is empty, the light from LED D1504 is reflected by the mirror installed on the toner cartridge drive unit, transmits
the yellow toner cartridge frame and reaches the photo transistors Q1504, turning the photo transistor Q1504 on. When the photo
transistor Q1504 is turned on, the voltage signal EMPY (pin 4 of IC7) becomes the reference voltage approximately +13.2V or less,
sending the high level toner empty detection signal EMPY from pin 2 of the comparator IC35 to pin 207 of IC14.
When the toner cartridge is installed:
Detection of the toner cartridge, toner low or toner empty is performed when the power is turned on (or toner cartridge cover is
opened & closed).
When the toner is not empty or not low:
When the toner is empty or low:
When the toner cartridge is not installed:
Detection of the toner cartridge is performed when the power is turned on (or when the toner cartridge cover is opened & closed).
When the toner cartridge is not installed, the signal EMPY usually is high when the signal EMPLEDY is high because the light from
D1504 is not blocked by the toner or sensor paddle (see the following Figure-1). Within a predertermined time, the signals EMPY
and signal EMPLEDY which IC14 receives are the same in pulse number. As a result, the CPU recognizes that the toner cartridge
is not in the printer. The user error message "TC-Y Not Installed" is displayed on the LCD display.
The black, magenta and cyan toner empty detection circuits function in the same manner as the yellow toner empty detection
circuit.
The signal EMPY usually is low because the light from D1504 is blocked by the toner in the
toner cartridge. Within the predetermined time, IC14 cannot receives the predetermined high
level pulse number of signal EMPY. As a result, CPU recognizes that the toner cartridge is in
the printer and the toner is enough.
The sensor paddle, which rotates when the OPC is rotating, is located in the toner cartridge
(see the following Figure-1). When this sensor paddle is in the light path, the signal EMPY is
low because the light from D1504 is blocked by the sensor paddle. If the toner is empty or low,
IC14 receives the high level pulse number of signal EMPY less than the pulse number of
signal EMPLEDY within a predetermined. As a result, the CPU recognizes that the toner
cartridge is the toner empty or low. Detection of the low (or toner empty) is performed when
the OPC is rotating. If the toner is low (or empty), the user error message "Low Yellow Toner
"(or "TC-Y Toner Empty) is displayed on the LCD display.
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