OKIDATA OKIPAGE 20, Service Manual

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Page: 17
Service Manual - OKIPAGE20
Chapter 2 Operation Description
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 together as a pair.
The LED correcting head consists of the correction control LSI , LED drivers , and an LED array. The
block diagram of the LED correcting head is shown below.
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.
In the OKIPAGE 20 Series Printer, the correction control of LED head is executed by CPU. The procedure
is as follows
(1) LED head is set to the correction control read mode and all correction data stored in EEPROM within
the correction control LSI are read by CPU, and stored temporarily in the memory.
(2) Next, LED head is set to the correction control direct mode and the correction data stored temporarily
in the memory is transferred directly to the LED driver.
(1) Read of correction data