Oki OKIOFFICE44 Service Manual page 271

A3.1.7 R44 Circuit Diagram
1. Block diagram
The circuit diagram consists of connector CN14 that provides an interface between R44 board and
LED print head.
Figure A3.1.7 shows the related signals and block diagram of LED print head.
2. Function
Data of 1664 LEDs on the LED print head is loaded into the shift registers by the HCLCK (1.0
MHz) signal. After the 1664 bit (208 mm) data is loaded in the shift registers, it is then loaded in
the latch circuit by the HLATCH signal. The turning -on and off of the LEDs are controlled by
STRB1-N to STRB4-N signals.
LED head interface signals output from IOGA1
• HDATA 0
• HCLCK
• HLATCH
• STRB1-N to STRB4-N : LED head strobe signals
IC2
HCLCK (1.0 MHz)
HDATA 0
HLATCH
IOGA
STRB1-N to STRB4-N
Figure A3.1.7 Related Signals and Block Diagram of LED Head
Board Descriptions
: Print data i.e., data to be printed
: Transfer clock for print data (4.0 MHz)
: Latch signal for print data
R44
CN14
8
6
9
10, 11, 12, 13
1, 2
0 VP
3, 4
+5 V
5, 14
0 V
A - 29
LED print head
Shift register
Latch
Strobe
+5 V
0 V
OKIOFFICE 44 Serv. Man., P/N 59276801
LED
1664 bits (208 mm)