DOWNLOAD Panasonic KX-FT57E Service Manual ↓ Size: 3.76 MB | Pages: 127 in PDF or view online for FREE

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126

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A

A

B

C

B

C

28
27
26
25
22
24
23
49

38

STB1
STB2
STB3
STB4
THDAT
THCLK
THLAT
ADSEL1

AIN2

IC1

C39

C38

R49

R48

R47

C37

THERMAL
HEAD

5V

0V

0V

Effective Signal

Bezugspegel-Clamp

1.5V

Internes Vorspannungs-
Clamp von IC1

The thermal head temperature is converted to voltage by the thermistor and changed to digital data by using the A/D
converter of IC1. The CPU decides the strobe width of the thermal head according to this value. Therefore, this circuit can
keep the thermal head at an even temperature in order to stabilize the printing density and prevent the head from being
overheated.

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127

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(1) Line information is read the by the CCD, via  route 

@

 and is input to IC1.

(2) In IC1, data is adjusted to a suitable level for A/D conversion in the  Analog Signal Processing Section, and via route 

A

 it

is input to A/D conversion (8 bit). After finishing A/D conversion, the data is input to the Image Processing Section via
route 

B

. Via routes 

C

 and 

D

 , it is stored in RAM as shading data.

(3) The draft’s information that is read by the CCD is input to IC1 via route 

@

 , and after adjusted to a suitable level for A/D

conversion via route 

A

 , the draft’s information is converted to A/D (8 bit) and it is input to the Image Processing Section.

For the other side, the shading data which flows from the RAM via routes 

E

 and 

F

 is input to the Image Processing

Section. After finishing the draft’s information image processing, white is regarded as “0” and black is regarded as “1”. Via
routes 

C

 and 

D

 they are stored in RAM.

(4) The white/black data stored as above via routes 

E

 and 

G

 is input to the P/S converter. The white/black data converted to

serial data in the P/S converter is input to the Thermal Head via route 

H

 and it is printed out on recording paper.

Standard:

Read 3.85 times/mm

Fine:

Read 7.7 times/mm

Super-Fine:

Read 15.4 times/mm

Transmission
(1) Is the same processing as COPY items 1) - 3).
(2) Data stored in RAM as IC1 is output from IC1 via routes 

E

 and 

I

 , and is stored in the system bus. Via  route 

J

 , it is

stored in the communication buffer inside the RAM (IC3).

(3) While retrieving data stored in the communication buffer synchronously with the modem, the CPU inputs the data to the

modem along route 

K

 where it is converted to serial analog data and forwarded over the telephone lines via the NCU

Section.

Reception
(1) Serial analog image data is received over the telephone lines and input to the modem via the NCU section where it is

demodulated to parallel digital data. Then the CPU stores the data in the communication buffer of the RAM (IC3) along
route 

K

 .

(2) Data stored in the RAM (IC3) is decoded by the CPU via of route 

K

 , and is stored in the RAM  by routes 

L

 and 

D

.

(3) Is the same processing as COPY item 4).

LED ARRAY

MAIN BOARD

5V (LED ON)
0V (LED OFF)

+24V

ABOUT 10V (LED OFF)
0V (LED ON)

IC1

62

IOP26

IC7

16

1

The LED ARRAY will light during transmission and copying as a light source to recognize document characters, patterns, or
graphics on a document.
It is also possible to light the LED ARRAY in the test mode.

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128

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IC3

RAM

IC2

ROM

11

12

SYSTEM

BUS

MODEM

NCU

TEL LINE

P/S
CONVERTER

THERMAL
HEAD

CPU

RAM

IMAGE

PROCESSING

SECTION

A

D

ANALOG
SIGNAL

CCD
IMAGE
SENSOR

PROCESSING
SECTION

IC1

2

1

9

3

7

8

4

5

6

10

13

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129

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There are 18 driver ICs aligned horizontally on the thermal head and each one of these ICs can drive 96 heat emitting
registers. This means that one line is at a density of 96

~

18=1728 dots=(8 dots/mm).

White/Black (white=0, black=1) data in one line increments is synchronized at IC1 pin 24 (THCLK) and sent from IC1
pin 22 (THDAT) to the shift register of the ICs. The shift registers of the 18 ICs are connected in a series, and upon shifting of
the 1728 dot increment, all the shift register becomes filled with data and a latch pulse is emitted to each IC from IC1
pin 23 (THLAT).

With this latch pulse, all of the contents of the shift registers are latched to the latch registers. Thereafter, through the
addition of a strobe from the IC1 pins (25, 26, 27, 28), only the dot location of black (=1) among latched data activates the
driver and a current passes to a heat emitting body to cause heat emission.
Here the strobe of the four lines STB1 to STB4 impresses at intervals of 9.216 msec, as required for one-line printout, for
each 1/4th of the 18 IC units (4 units or 5 units) at each time interval divided into four equal increments.
The sequence is as shown the timing chart (Next page). [Moreover, for strobe width, the resistance value of the thermistor
inside the thermal head is constantly detected by IC1 pin 38, and values from the ROM (IC2) table corresponding to the
temperatures eliminate density temperature changes through the setting in the CPU.]
When the thermal head is not used, the IC1 (119, TH-POWER) becomes low, IC7 becomes OFF, RL201 breaks, and the
+24 V power supply for the thermal head driver is not impressed to protect the IC.

Thermokopf

Thermal Recording Paper

Transportwalze

This unit utilizes state of the art thermal printer technology.
The recording paper (roll paper) is chemically processed. When the thermal head contacts this paper it emits heat
momentarily, and black dots (appearing almost as points) are printed on the paper.

COMPOSITION OF THE RECEIVE RECORDING SECTION (THERMAL RECORDING FORMAT)