Panasonic KX-FP342CX, Service Manual

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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 registers. 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 IC520 pin 39
(NEWTHCLK), and sent from IC520 pin 40 (NEWTHDAT) to the shift register of the ICs. The shift
registers of the 9 ICs are connectedin 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 IC520 pin 38
(NEWTHLAT).
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 IC520 pins 44 and 45, only the dot location of
black (=1) among latched data activatesthe driver, and the current passes to heat the emitting
body to cause heat emission.
Here, the two line strobes, NEWSTB1 to NEWSTB2, impress as required for one-line printout.
When the thermal head is not used, the IC501 pin 137 (THON) becomes low, Q501 turns OFF,
IC506 turns OFF, and the +24V power supply for the thermal head driver is not impressed to
protect the IC.
3. Print Speed of Copier
2ppm 4ppm when copied meeting with the following conditions;
(1) Resolution: Fine
(2) Scale: 100%
(3) Print duty: 50% or less
*standard chart: ITU-T No.1 (Refer to
ITU-T No.1 TEST CHART ().)
(i) Print Duty 50% or less
The sequence is shown on
TIMING CHART ().
When print duty is 50% or less, IC520 pin 44 and 45 (NEWSTB1/NEWSTB2) are composed IC501
pin 103 (STB1) and IC501 pin 104 (STB2). (logic-AND)
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