Panasonic KX-FC228UA-T / KX-FC228RU-T Service Manual ▷ View online
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KX-FC228UA-T/KX-FC228RU-T
6.4.3.
Thermal Head
1. Function
This unit utilizes the state of the art thermal printer technology.
The ink film is chemically processed. The ink film is comprised of two parts: an ink layer and a base film. When the thermal
head contacts this ink film, it emits heat momentarily, and the ink layer is melted and transferred to the paper. If this continues,
letters and/or diagrams appear, and the original document is reproduced.
The ink film is chemically processed. The ink film is comprised of two parts: an ink layer and a base film. When the thermal
head contacts this ink film, it emits heat momentarily, and the ink layer is melted and transferred to the paper. If this continues,
letters and/or diagrams appear, and the original document is reproduced.
2. Circuit Operation
Refer to the block diagram and the timing chart on the following page.
There are 9 driver ICs aligned horizontally on the thermal head and each one of these ICs can drive 192 heat-emitting regis-
ters. This means that one line is at a density of 192
There are 9 driver ICs aligned horizontally on the thermal head and each one of these ICs can drive 192 heat-emitting regis-
ters. This means that one line is at a density of 192
×9=1728 dots=(8 dots/mm).
White/Black (white=0, black=1) data in one line increment is synchronized at IC10 pin 117 (THCLK), and sent from IC10 pin
116 (THDAT) to the shift register of the ICs. The shift registers of the 9 ICs are connected in series, and upon the shift of the
1728 dot increment, the shift register becomes filled with data, and a latch pulse is emitted to each IC from IC10 pin 118
(THLAT).
With this latch pulse, all the contents of the shift registers are latched to the latch registers. Thereafter, through the addition of
strobes from the IC10 pins (103, 104), only the dot location of black (=1) among latched data activates the driver, and the cur-
rent passes to heat the emitting body to cause heat emission.
Here, the two line strobes, STB1 and STB2, impress at intervals of 9.216 msec, as required for one-line printout.
The sequence is shown on the next page. [Moreover, for the strobe width, the thermistor value inside the thermal head is
detected according to IC10 pin 4. Depending on that value, the strobe width is recorded in FLASH ROM (IC16). Accordingly,
the strobe width is determined.]
When the thermal head is not used, the IC10 (17, THON) becomes low, Q603 turns OFF, Q401 turns OFF, and the +24V
power supply for the thermal head driver is not impressed to protect the IC.
116 (THDAT) to the shift register of the ICs. The shift registers of the 9 ICs are connected in series, and upon the shift of the
1728 dot increment, the shift register becomes filled with data, and a latch pulse is emitted to each IC from IC10 pin 118
(THLAT).
With this latch pulse, all the contents of the shift registers are latched to the latch registers. Thereafter, through the addition of
strobes from the IC10 pins (103, 104), only the dot location of black (=1) among latched data activates the driver, and the cur-
rent passes to heat the emitting body to cause heat emission.
Here, the two line strobes, STB1 and STB2, impress at intervals of 9.216 msec, as required for one-line printout.
The sequence is shown on the next page. [Moreover, for the strobe width, the thermistor value inside the thermal head is
detected according to IC10 pin 4. Depending on that value, the strobe width is recorded in FLASH ROM (IC16). Accordingly,
the strobe width is determined.]
When the thermal head is not used, the IC10 (17, THON) becomes low, Q603 turns OFF, Q401 turns OFF, and the +24V
power supply for the thermal head driver is not impressed to protect the IC.
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KX-FC228UA-T/KX-FC228RU-T
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KX-FC228UA-T/KX-FC228RU-T
6.4.4.
Scanning Block
The scanning block of this device consists of a control circuit and a contact image sensor made up of a celfoc lens array, an LED
array, and photoelectric conversion elements.
array, and photoelectric conversion elements.
When an original document is inserted and the start button pressed, pin 138 of IC10 goes to a low level and Q20 are turned ON, pin
34 of IC10 goes to a high level and the transistor Q21 turns on.This applies voltage to the LED array to light it. The contact image
sensor is driven by each of the FTG-F1 signals output from IC10, and the original image illuminated by the LED array undergoes
photoelectric conversion to output an analog image signal (SIG). The analog image signal is input to the system ASIC on AIN1 (pin
3 of IC10) and converted into 8-bit data by the A/D converter inside IC10. Then this signal undergoes digital processing in order to
obtain a high-quality image.
34 of IC10 goes to a high level and the transistor Q21 turns on.This applies voltage to the LED array to light it. The contact image
sensor is driven by each of the FTG-F1 signals output from IC10, and the original image illuminated by the LED array undergoes
photoelectric conversion to output an analog image signal (SIG). The analog image signal is input to the system ASIC on AIN1 (pin
3 of IC10) and converted into 8-bit data by the A/D converter inside IC10. Then this signal undergoes digital processing in order to
obtain a high-quality image.
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KX-FC228UA-T/KX-FC228RU-T
6.4.5.
Stepping Motor Drive Circuit
1. Function
One individual stepping motor is used for transmission and reception. It feeds the document or recording paper synchronized
for reading or printing.
for reading or printing.
2. Circuit Operation
During motor driving, pin 124 of ASIC IC10 becomes a high level, and Q403, Q402 turns ON. As a result, +24V is supplied to
the motor coil.
Stepping pulses are output from ASIC IC10 pins, 120~123, causing driver IC401 pins, 11~14 to drive the Motor Coil. The
motor coil is energized sequentially in 2 phase increments, which causes a 1-step rotation. A 1-step rotation feeds 0.13 mm of
recording paper.
The timing chart is below.
the motor coil.
Stepping pulses are output from ASIC IC10 pins, 120~123, causing driver IC401 pins, 11~14 to drive the Motor Coil. The
motor coil is energized sequentially in 2 phase increments, which causes a 1-step rotation. A 1-step rotation feeds 0.13 mm of
recording paper.
The timing chart is below.
Stepping Motor Drive Mode
Function
Mode
Phase Pattern
Speed
Copy
Fine, Photo
1-2
432 pps (t=1/432)
Super Fine
1-2
216 pps (t=1/216)
FAX Sending
Standard
2-2
432 pps (t=1/432)
Fine, Photo
1-2
432 pps (t=1/432)
Super Fine
1-2
216 pps (t=1/216)
FAX Receiving
Standard, Fine, Photo
1-2
432 pps (t=1/432)
Super Fine
1-2
216 pps (t=1/216)
Paper Feed
———
1-2
432 pps (t=1/432)
Document Feed
———
1-2
432 pps (t=1/432)
Stand-by
———
All phases are currently off.
None
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