Engine Control System; Video Controller; Outline; Outline Of Operation By Block - Canon LBP3300 Series Service Manual

Table of Contents

Chapter 2

2.7 ENGINE CONTROL SYSTEM

2.7.1 Video Controller

2.7.1.1 Outline

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.

2.7.1.2 Outline of Operation by Block

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 un-

changed (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 8 MB of memory, and has the following function:

1. temporarily retains the dot data (reception buffer) that has been converted from image data.

2.7.2 Engine Controller

2.7.2.1 Outline

The engine controller circuit controls the operational sequences of the printer. It consists of the memory tag circuit, the fixing control circuit, the high-voltage power

supply circuit, the low-voltage power supply circuit, and the fan motor drive circuit,

The block diagram of this circuit is illustrated below and each circuit is described in the following.

2-20

External device

<J3>

USB interface

X'TAL 2

X'TAL 1

Internal RAM

30MHz

12.09MHz

8MB(IC4)