Oki OKIOFFICE 84 Service Manual page 392

A3.1.6 R51 Circuit Diagram (Page 6/12)
1. Block diagram
The circuit diagram shown on page 6/12 consists of connector CN12 that provides an interface between R51 board
and LED print head.
Figure A3.1.6 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 (4MHz or 6.7 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 IOGA4
l
HDATA 0 : Print data i.e., data to be printed
l
HCLCK : Transfer clock for print data (4.0 MHz or 6.7 MHz)
l
HLATCH : Latch signal for print data
l
STRB1-N to STRB4-N : LED head strobe signals
Figure A3.1.6 Related Signals and Block Diagram of LED Head
Service Guide OKIOFFICE 84
Chapter A Board Descriptions
Page: 234