Oki OKIPAGE 12i Series, Service Handbook

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2.3.4 Revision of LED Head Illumination
An LED correcting head, which is capable of correcting the illumination of the LED for each dot,
is being used in this printer. LED illumination correction function of 16 steps is carried out by using
an EEPROM which is installed in the LSI that maintains the LED illumination correction values,
and an LED correction drivers (MSM6731BWAF or MSM6732BWAF) together as a pair.
The LED correcting head consists of the correction control LSI (MSM6730WAF), LED drivers
(MSM6731BWAF or MSM6732BWAF), and an LED array. The block diagram of the LED
correcting head is shown below.
The existing LED head receives the printing data from the CPU directly at its LED drivers. With
the LED correcting head, a correction control LSI (MSM6730WAF) is connected between the
CPU and LED drivers, so the printing data is input to the LED drivers through the correction control
LSI. In order to maintain compatibility with the existing LED head, the printing operation of the
LED correcting head is carried out through identical sequence.
The LED correcting head is a 600 dpi head, with the LED drivers located on both sides of the LED
array with a 300 dpi pitch spacing. The printing and correction data obtained from the CPU
through four signal lines are sent to the LED array.
STRB1-N
STRB2-N
STRB3-N
STRB4-N
LOADI
CLOCKI
DATAI0
DATAI1
DATAI2
DATAI3
MSM6730
WAF
EEPROM
Correction
Values
LED LED LED LED LED LED LED
LED Driver
MSM6732BWAF
LED Driver
MSM6732BWAF
LED Driver
MSM6731BWAF
LED Driver
MSM6731BWAF
LED Array
Printing and correction data combined signal line
Correction data signal line
From
CPU