Canon LBP-3000, Руководство по обслуживанию

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Chapter 2
2-19
2.7 ENGINE CONTROL SYSTEM
2.7.1 Video Controller
2.7.1.1 Overview
0008-0510
The video controller receives print information from an external device (e.g., host computer) through an interface cable. The print information includes the
CAPT command used to communicate printer status and unique information and dot data, which is the result of conversion of resource type print data by
the host computer. The dot data is sent to the engine controller for control of the activation of the laser diode.
The external device can check the status of the printer unit by means of a bi-directional interface.
F-2-20
2.7.1.2 Outline of Operation by Block
0008-0552
1. EEPROM (IC1)
It possesses 128 bytes of memory, permitting writing of data and erasing of it electrically. It is used to retain parameters of the printer unit that must remain
unchanged (e.g., USB serial number, printing environment; these parameters are retained when the power is turned off/on).
2. ASIC (IC2)
It has the following functions:
1. controls the input/output of the internal RAM.
2. controls the timing at which dot pattern data is sent to the engine controller.
3. decompresses the image data that has been compressed.
3. CPU (IC3)
It has the following functions:
1. processes the serial commands of the video interface.
2. transmits and receives the CAPT command through the USB interface.
3. controls the display panel interface.
4. DRAM (IC4)
It possesses 2 MB of memory, and has the following function:
1. temporarily retains the dot data (reception buffer) that has been converted from image data.
<J3>
ASIC ( IC2)
CPU
( IC3)
<J4>
X'TAL 1
8.17MHz
X'TAL 2
30MHz
<J1>
EEPROM
(IC1)
Internal RAM
2MB (IC4)
USB interface
Video interface
Display panel
Engine controller
External device