Ricoh G3BASIC BASICEUR

GROUP 3

FACSIMILE

INTRODUCTION

This is a reference book containing general descriptions of the mechanisms, circuits, and data processing techniques that are common to most Group 3 facsimile machines.

Details such as the timing of various mechanical operations, error conditions, and the types of adjustment available differ widely from model to model. Because of this, the descriptions in this book are general. For more specific details concerning a particular model, the reader must refer to the Service Manual for that model.

However, in some cases, it is possible to be more comprehensive, and this has been done wherever possible. For example, the operation of the relays and the other components in the network interface hardware have to meet local governmental requirements. These requirements are different for each country, but each model has to operate in the same way.

Future Service Manuals will not contain extensive descriptions of theory, processes, or circuits. They will only contain machine-specific field service related information. There will be some short descriptions to outline important points and to explain any variations in standard processes. In addition, as scanner and printer mechanisms often vary widely from model to model, Service Manuals will illustrate these. Important mechanisms and circuits, such as those related to safety in laser printers, will be covered. Wherever necessary, the Service Manuals will contain references to this book so that the reader can pick up background information.

New models often employ new techniques, so updates and addenda to this book will be issued to cover these in the future as they arise. New pages will be issued in the form of a technical bulletin. Recipients of these pages will be able to add them to the relevant sections of this manual.

This book consists of the following sections.

Section 1. Fax Machine Overview

This section outlines the processes used in thermal and laser faxes.

Section 2. Transmission

This section explains how a fax machine scans and transmits a fax message.

Section 3. Reception - Thermal Printers

This section explains how a thermal printer based fax machine receives and prints a fax message.

Section 4. Reception - Laser Printers

This section explains how a laser printer based fax machine receives and prints a fax message.

Appendix A. Facsimile Specifications and Features

This section briefly explains each of the specifications and features that are quoted at the front of each Service Manual.

Appendix B. Protocol

This section outlines the protocol signalling between two fax terminals. It explains how features such as Turnaround Polling and Transfer Request are executed. ECM is also explained.

Appendix C. Troubleshooting Techniques

This section describes general troubleshooting techniques, including communication troubleshooting.

Appendix D. Commonly-used Components

This section gives a little theoretical background on components such as CCDs, thermal heads, and motors.

Appendix E. Compression Techniques

This section explains the data compression techniques used by fax machines.

Appendix F. Modulation Techniques

This section explains modulation techniques used by fax modems.

Appendix G. Table of Model Names

This is a table of the model names used in various regions.

Appendix H. Facsimile History and Background

This section supplies some information concerning the history of the development of the facsimile machine.

SECTION 1. FAX MACHINE OVERVIEW

This section outlines the facsimile processes used in thermal and laser faxes. The following sections are included.

Section 1-1. Facsimile Process

This section explains what a fax machine is and briefly outlines the major mechanical processes involved in transmitting and receiving a fax message.

Section 1-2. Overall Machine Control

This section describes how a typical fax machine is controlled. The functions of major electronic components and memory units are explained. The various methods of communication between cpu’s are also outlined.

Section 1-3. Video Data Path

This section shows the path of facsimile data through the machine. The paths for transmission and reception are explained.

Section 1-4. Power Distribution

This section shows how power is distributed through a typical fax machine. Memory back-up circuits and safety features are also described.

1-1. FACSIMILE PROCESS

This section has two purposes.

• To briefly explain what a fax machine is.

• To broadly outline each phase of the transmission and reception proc-

esses (each step is explained in more detail in sections 2, 3, and 4). For each machine, there will be slight differences but the basic steps are the same. Examples are given for thermal and plain paper fax terminals.

1-1-1. What is a Fax Machine?

Facsimile, commonly known as fax, is used for sending written, printed, or graphic information from one location to another. The communication can be across the room or across the world. A simple block diagram of fax operation is shown below.

ORIGINAL

RECEIVED

FAX MESSAGE

--- ---- -- ---- -

------ --- ---- --

---- --- - - --- -

-- -- -

- -- --

-- -- -

- --- -

-- ---- -- --- --

SCANNING

CONVERSION

TRANSMITTING

FAX MACHINE

TELEPHONE LINE

--- ---- -- ---- -

------ --- ---- --

---- --- - - --- -

-- -- -

- -- --

-- -- -

- --- -

-- ---- -- --- --

PRINTING

CONVERSION

RECEIVING

FAX MACHINE

Facsimile machines combine scanner and printer technology with telephone equipment to send copies to a remote location. There are three basic steps in a facsimile transmission.

• A light source scans the writing and drawings on the original, and con-

verts the information into an electrical signal.

• This signal is sent over the telephone line to a receiving fax machine.

• The receiving machine converts the incoming signal into a copy of the

original.

Facsimile machines can transmit alphanumeric and graphic characters. Anything that can be put on paper, from handwritten notes to photographs, can be sent by fax.

1-1-1

1-1-2. Thermal Paper Fax Terminals

These machines contain a thermal printer.

1. Transmitting

Exposure

[B]

Document Feed

[A]

[C]

1. Document Feed

The original (also known as the document) is fed into the scanner [A] one page at a time.

2. Exposure

A fluorescent lamp or xenon lamp [B] illuminates the document as it passes the exposure glass. Light reflected from the document passes to the CCD (Charge Coupled Device). The CCD [C] converts the light reflected from the document into an analog electrical signal.

3. Transmission

Other circuits inside the machine take the output from the CCD and convert it into a data signal for transmission over the telephone network.

1-1-2

2. Receiving

[C]

Cutting

[D]

Printing

[A]

Paper Feed

[B]

1. Reception of Data

Circuits inside the machine take the signal from the telephone line and convert it into a series of black and white dots for printing.

2. Paper Feed

The rx motor drives the platen roller [A], which feeds the thermal paper [B] past the thermal head [C].

3. Printing

To print the data, the machine uses a thermal head. The thermal head consists of a line of heating elements. The paper is specially treated to make it turn dark when heated. The received data is reproduced one line at a time as the paper is fed past the thermal head; a black dot on the line currently being printed is reproduced by heating the element at the appropriate location on the thermal head.

4. Cutting

After printing, the cutter [D] automatically cuts off the received page from the paper roll. Some machines do not have a cutter.

1-1-3

1-1-3. Plain Paper Fax Terminals

These machines contain a laser printer. Two types of printer mechanism are commonly used; one uses positively-charged toner, and one uses negativelycharged toner. Note the differences in charge polarities in some of the printing processes. The master unit is the centre of the printer, as shown below.

1. Transmitting

This is exactly the same as for thermal paper fax terminals.

2. Receiving

[O]

Quenching

[N]

Cleaning

Fusing

[M]

[L]

Charge

Transfer

[A]

Exposure

[C]

[J]

Registration

[K]

[D]

[E]

[B]

[G]

[F]

Development

[H]

Paper Feed

[I]

1. Reception of Data

Circuits inside the machine take the signal from the telephone line and convert it into a series of black and white dots for printing.

2. Charge

In the dark, the charge corona wire [A] gives a negative charge to the master [B]. The grid plate [C] under the charge corona wire ensures that the charge is applied uniformly. The negative charge remains on the surface of the master because the master has a high electrical resistance in the dark.

1-1-4

3. Exposure

The received data signal is converted into a series of black and white dots for printing. Write-to-white (positive toner): To print the data, a laser beam [D] scans across the master, switching on to make a white dot on the copy, and switching off to make a black dot. Write-to-black (negative toner): The laser beam switches on to make a black dot on the copy, and switches off to make a white dot. Both types: The charge on the master goes to ground in areas exposed to the beam, thus producing an electrical latent image [E] on the master surface.

4. Development Write-to-white (positive toner): A thin layer of positively charged toner [F]

on the development roller [G] comes into contact with the latent image on the master surface. Toner particles are attracted to the negatively charged areas of the master belt surface [H]. Write-to-black (negative toner): A thin layer of negatively charged toner on the development roller comes into contact with the latent image on the master surface. Toner particles are attracted to the least negatively charged areas of the master belt surface.

5. Paper Feed

Paper [I] is fed from the cassette. The paper is plain paper, as used in a photocopier.

6. Registration

The registration roller [J] stops the paper momentarily to correct skew, and it allows the paper into the image transfer area [K] at the correct time.

7. Image Transfer

Copy paper is fed to the master surface while the transfer corona wire [L] applies a strong charge to the back of the paper; the charge is of opposite sign to that of the toner. This charge pulls the toner particles from the master surface onto the paper. The paper then separates from the master and passes into the fusing unit.

8. Fusing

In the fusing unit [M], the image is fused to the copy paper by two rollers which apply heat and pressure.

9. Cleaning

In preparation for the next copy, the cleaning blade [N] removes any remaining toner from the master surface.

10. Quenching

The light from the quenching lamp [O] electrically neutralizes the master surface.

1-1-5

1-2. OVERALL SYSTEM CONTROL

This section shows how a fax machine is organized and controlled. The responsibilities of each cpu and major control component are described.

The internal organization of most fax machines is very similar. Typical examples are given below. Note that the diagrams show only how the machine is controlled; the path of video data is not explained in this section.

1-2-1. Thermal Paper Fax Machines

Scanner

Sensors

Operation

Panel CPU

Voice Message

Processor

Memory

External

Line Handset

Tel

Network

Interface

Circuits

CPU

CONTROL SIGNALS

I/O

Port

SBU (CCD)

Video Processing

Memory

Video

Processor

Scanner and Printer Drive Components and Sensors

Thermal

Head

THERMAL PRINTERS

ONLY

Modem

DATA AND ADDRESS BUS

RAMROM

SAF

Memory

ECM

Memory

FIFO

Line

Buffer

The centre of the machine is the cpu. This controls the machine. (In machines that have more than one major cpu, the controlling cpu is called the Main CPU.) An LSI gate array called the I/O Port controls much of the machine in conjunction with the cpu. So, to simplify the diagram, the cpu and the I/O Port are considered to be one unit.

1-2-1

Data and address buses link the cpu to the major data processing and storage components of the machine. Control signals drive the mechanical and electrical components of the scanner, network interface, and printer.

The components shown on the diagram on the previous page are explained below.

ROM (Read Only Memory)

This contains the system software, which controls all aspects of the machine’s operation.

RAM (Random Access Memory)

This contains work areas for the cpu, and programmable system parameters (such as bit switches). If the main power is switched off, the RAM is not erased. This is because a battery supplies back-up power to the RAM if the main power is off (see section 1-4-3 for more details on battery back-up).

Static RAM ( SRAM), Pseudo-static RAM (PSRAM), and Dynamic RAM ( DRAM)

SRAM can be connected to a battery, which provides back-up power if the main power switch is turned off. (In some cases, a capacitor with a high charge capacity is used to supply back-up power to the SRAM.) The power from the battery prevents the data from being erased. SRAM is commonly used for storing vital system parameters, but may also be used as SAF memory. However, the high cost of SRAM prevents its use as SAF memory in low-cost fax machines.

Recently developed types of DRAM can also be backed up by a battery. However, unlike SRAM, it needs a periodic refresh from a DRAM controller or the contents are erased. The SAF memory in most fax machines is DRAM.

PSRAM, like SRAM, can be backed up by a battery and does not need periodic refresh. However, PSRAM is more like DRAM in its internal structure.

SAF Memory (Store And Forward Memory)

When a user stores a fax message in the memory for sending later or broadcasting, the message goes into the SAF memory. Also, incoming confidential messages and ’substitute’ receptions are held in this memory.

Not all fax machines have this memory. In some models with no or low SAF memory capacity, the ECM memory may be used as a SAF memory. The exact method of use and the limitations on use differ from machine to machine. However, generally, battery back-up is disabled while the memory is being used for ECM.

SAF memory is usually DRAM, but the small SAF/ECM memory is usually PSRAM.

1-2-2

Line Buffer

This memory buffer ensures synchronization of video data transfer between different components of the circuit (see section 1-3). If the line buffer is too small, the scanner mechanism will have to keep stopping and starting, leading to excessive noise. A line buffer size of four or eight lines is typical.

ECM Memory (Error Correction Mode Memory)

ECM is an optional extension to Group 3 protocol that provides a more reliable way to send data over noisy lines. Using ECM, data is assembled into protocol frames. ECM requires RAM for assembly into and extraction from protocol frames. This memory is the ECM memory; it is normally PSRAM, without battery back-up.

With ECM, image data is arranged in protocol frames (256 bytes in each frame), and transmitted in blocks made up of 256 frames. Therefore, each block is 64 kbytes. Normally, one page of compressed image data can be sent in one block, but more than one may be needed if halftone mode was used when scanning the original.

Single Buffer and Double Buffer ECM Memory Single Buffer (64 kbytes): This memory is only large enough to hold one block. After

receiving a block of compressed facsimile data from the remote terminal into ECM memory, the data is reconstructed and printed. The next block cannot be received until printing has finished. The first block is deleted from memory after printing. Double Buffer (128 kbytes): This memory can hold two blocks. While one block is being printed, the next block can be received into the other half of the double buffer memory. This ensures continuous operation, saving time and overall communication charges.

In some machines with a single buffer only, SAF memory or hard disk memory are used to provide double buffer capability.

ECM is explained in more detail in Appendix B. For full details, see a recent version of CCITT recommendation T.30.

FIFO Memory (First-In First-Out Memory)

The FIFO synchronizes the transfer of video data to the modem (transmission) or from the modem (reception). It also acts as a buffer, ensuring that there is always some data for the modem to pick up, modulate, and send out. The FIFO also has some unique functions, in addition to synchronizing data transfer from the cpu to the modem, as explained in section 2-8.

The actual use of the FIFO and Line Buffer in each communication mode is outlined in section 1-3.

CCD (Charge Coupled Device)

The CCD generates the video image signal. This is an analog signal.

1-2-3

Modem

During transmission, the modem converts the data into a form that can be sent out on the telephone line in accordance with the appropriate CCITT V-series recommendations; this process is called Modulation. During reception, the modem converts incoming data into a form that the machine can work with; this process is called Demodulation. The term ’modem’ is derived from these two processes; MOdulation/DEModulation. The different types of modulation encountered in fax machines are described in appendix F (for full details see the CCITT V-series recommendations).

Video Processor

This contains circuits that process the output of the CCD. Using digital techniques, the quality of the image can be improved before transmission.

Video Processing Memory

Some of the digital video processing techniques require a work area.

Scanner and Printer Drive Components and Sensors

Every machine has motors, lamps, solenoids, electromagnetic clutches, sensors, and switches.

Thermal Head

This prints received images on the thermal paper.

Network Interface Circuits

The filters, relays, attenuators and other components in these circuits interface the machine with the public telephone network. These circuits ensure that the machine connects to the line and dials in the correct way. They also ensure that the machine and the network equipment do not damage each other.

Voice Message Processor

This converts voice messages from analog (audio) to digital for storage in the memory. It also retrieves the message for memory when it is needed for sending out over the telephone line.

Operation Panel

This is the ’user-machine interface’. The operation panel may have one or two cpu’s to control the LCD, and the keys and indicators. In many models, the operation panel cpu’s monitor the sensors in the scanner mechanism. The operation panel may contain a microphone for storing the voice message and for making telephone conversations as part of a speakerphone; however, the handset is normally used for these purposes.

1-2-4

1-2-2. Plain Paper Fax Machines

Plain paper fax machines, having a laser printer engine, are more complex, and often require more than one major cpu. The cpu that controls the machine overall is called the Main CPU (see section 1-2-1).

The areas directly controlled by the main cpu are the same those controlled by the cpu in thermal faxes (this is the basic facsimile engine, minus thermal head and printer components). The difference is that the printer components are often controlled through another major cpu, known as the slave cpu, as shown below.

Main CPU

Slave

CPU

I/O

Port

Buffer

DATA AND ADDRESS BUS

RAMROM

Printer Drive Components

I/O

Port

Page

Memory

and Sensors

Laser Diode

LIF

RAM

The additional components are as follows.

Slave CPU

This cpu controls the laser printer engine, under the control of the main cpu. It is assisted by an I/O Port, which is similar in function to that of the main cpu. (In some laser faxes, some of the scanner components are also controlled by the slave cpu.)

1-2-5

Buffer

This is an interface for commands, responses, and data passing between the two cpu’s.

Page Memory

This memory holds one page of data for printing. Printing does not begin until the complete page has been assembled here. Data from the network comes into the page memory through the modem (or from the SAF memory in the case of substitute or confidential reception), under the control of the main cpu.

LIF (Laser Interface)

When a complete page has been assembled in the page memory, it passes to the LIF. The LIF controls transfer of data from the page memory to the laser diode. It also contains data processing circuits, including those for smoothing the data to 16 x 15.4 dots/mm before printing.

RAM

The LIF uses this memory as a work area for data processing.

ROM

This contains printer control software.

Laser Diode

The machine writes the image on the master by switching a laser beam on/off. A laser diode generates this laser beam.

Printer Drive Components and Sensors

A laser printer mechanism is more complex than a thermal printer. The components of a laser printer will be explained in section 4.

Hard Disk

Some machines have a hard disk instead of a RAM SAF memory. The hard disk may also store system parameters, Quick Dial Codes and so on.

1-2-6

1-2-3. Communication Between CPU’s

Most machines have more than one cpu, but most of these are of minor importance, controlling certain areas of the machine, such as the operation panel. The major cpu’s control the machine, but delegate responsibilities to the other cpu’s. In thermal fax machines, there is one major cpu (called the cpu). Laser fax machines often have two major cpu’s; the overall controlling cpu is called the main cpu, and the other is called the slave cpu.

The number of cpu’s and their areas of responsibility vary from model to model, so descriptions of circuits in this manual will be very generalized.

Communication between cpu’s is normally done in one of two ways; a serial interface or a parallel interface. These are outlined below.

1. Serial Interface

COMMANDS

Main

CPU

RESPONSES

Slave

CPU

The serial interface most commonly used between two cpu’s consists of a command line from the main cpu, and a response line from the slave cpu. There may also be a clock signal to synchronize the interface, and a reset signal.

Serial interfaces are often used when the slave cpu shown in the diagram is a minor cpu for monitoring sensors and controlling mechanical components.

2. Parallel Interface

Main

CPU

Buffer

Slave

CPU

A parallel interface typically has 8 or 16 wires for carrying data between the two cpu’s. Data can pass in either direction on these wires. A buffer is normally included between the two cpu’s.

A parallel interface is normally used when the cpu is receiving and processing video data, as well as controlling mechanical components. A typical example would be between the main and slave cpu’s in a laser fax machine.

1-2-7

1-3. VIDEO DATA PATH

This section outlines the path of video data through the machine in transmission, reception, and copying modes.

1-3-1. Transmission

This section explains the path of data through the machine during transmission. The main description is for memory transmission with ECM. Following this main description are diagrams showing the differences between memory transmission with ECM and the following:

• Memory transmission without ECM

• Immediate transmission with ECM

• Immediate transmission without ECM

1. Scanning

Scanner

Fluorescent Lamp

Shading Plate

CCD

Lens Block

Profile

When the user presses the Start key on the operation panel, the original (also known as the document) passes into the scanner, where it is illuminated by the fluorescent lamp.

Light is reflected from the document through a shading plate, which allows more light to pass through from the ends of the lamp than from the centre; this compensates for the fact that the ends of the lamp are not so bright as the centre.

Other types of lamp Xenon lamp : If a xenon lamp is used, the difference in brightness is smaller than with a

conventional fluorescent lamp, and the xenon lamp is brighter, but this problem still exists. LED array: This is a strip of photodiodes. As all the diodes are equally bright, a shading plate is not needed.

After passing through the shading plate, the light is focused by the lens block onto the CCD.

1-3-1

2. Data Processing

Fluorescent

Lamp

Original

CCD

Analog Signal

ECM

Memory

SAF

Memory

Line

Buffer

To the

Network

Processor

FIFO

RAM

Variable Resistor

Video

CPU

8-bit

Attenuator

Modem

Gain Control

Circuit

CCD and Analog Video Processing

The CCD (Charge Coupled Device) is a row of photoelectric elements. It generates an analog video signal from the light reflected from the document. This signal passes to the Video Processor, which corrects the data for scanner irregularities and converts it to digital (the signal from each element of the CCD is typically represented by four bits).

For more about CCDs, see Appendix D.

Contact Image Sensor

In some cheaper models, a contact image sensor (CIS) is used instead of a CCD. The image sensor is directly below the exposure glass; no mirrors, lenses, or shading plates are used (the image sensor elements are self-focusing).

1-3-2

Digital Video Processing

The Video Processor also does digital video data processing (e.g., halftone, MTF), and converts the data to eight-bit parallel.

If the original is wider than the paper in the printer at the other end, data will be deleted in the main scan and sub-scan directions to make the data fit on the paper at the other end. This process is known as reduction.

After video processing, the signal from each CCD element is represented by one bit (unless reduction was done).

See section 2-3 for full details on video data processing.

Storage to SAF Memory

After leaving the Video Processor, the data is compressed and then stored in the SAF memory. The compression method used varies from model to model. A simple compression technique such as MH gives fast data storage, but the data takes up more room in the memory. More complex compression techniques such as MR or MMR compress the data more effectively so that less memory space is used, but they increase the scanning time.

Retrieval from SAF Memory

When it is time to send the data, the data comes out of the memory into the cpu. The cpu reconstructs the raw data, and passes it to the line buffer. (Lines of data that were stored as uncoded data go from the memory straight to the line buffer.)

Compression

The cpu then compresses the data in accordance with the method agreed in the set-up protocol that was exchanged between the two machines.

ECM Data Frame Assembly

Using the ECM memory, the cpu assembles the data into ECM data frames, which are sent to the modem and the line.

Modulation

The modem converts the data to serial and modulates it.

Attenuation

The data then passes through an attenuator, which adjusts the tx level (this is the output power of the data signal). It then passes through a variable resistor on the NCU, which can be used to adjust the tx level. The data then passes to the network.

Flow charts for the different transmission modes are given on the next page.

1-3-3

1. Memory Transmission, with ECM

Video

Processor

Reconstruction Compression

SAF

Memory

Line

Buffer

Line

Buffer

Compression

CPU

CPUCPU

ECM

Memory

Modem Attenuator

2. Memory Transmission, without ECM

Video

Processor

Reconstruction Compression

SAF

Memory

FIFO

Memory

CPU CPU

Modem Attenuator

3. Immediate Transmission, with ECM

Video

Processor

Line

Buffer

Line

Buffer

Gain

Control

Compression

CPU

Line

Gain

Control

Compression

CPU

ECM

Memory

Modem Attenuator

4. Immediate Transmission, without ECM

Video

Processor

FIFO

Memory

Modem Attenuator

Line

Buffer

1-3-4

Gain

Control

Compression

CPU

Gain

Control

1-3-2. Reception

This section explains the path of data through the machine during reception. The data paths for thermal printers and laser printers are explained separately.

The main description is for basic reception without ECM. Following this main description are diagrams showing the differences between basic reception with ECM and the following:

• Basic reception without ECM

• Memory reception without ECM

• Memory reception with ECM

1. Thermal Printers

From the

Network

SAF

Memory

Line

Buffer

ECM

Memory

Filter

I/O Port

Thermal

Head

Modem

CPU

Thermal

Paper

Data from the line passes through a filter to remove unwanted frequencies. Then it goes to the modem, which demodulates the data and converts it to parallel.

1-3-5

Reconstruction

The data coming from the modem is compressed data. This data passes from the modem through the FIFO memory to the cpu where it is decoded, using the line buffer.

Note: In machines with SAF memory, the data is also stored in the memory

in case the printer jams or runs out of paper; after the user corrects the fault, the message will be printed out from the memory and no data will be lost. However, in some models, if the paper ends but the paper end sensor did not detect a black stripe at the end of the roll, the page being printed will be lost.

Smoothing

The cpu then smooths the data, to remove jagged edges from the data. The resolution of the received data is upgraded into the highest that the printer can print; this is typically 8 x 7.7 dots per mm.

Printing

The cpu converts the data to serial, and passes it to the thermal head through the line buffer.

1-3-6

2. Laser Printers

From the

Network

SAF

Memory

Line

Buffer

ECM

Memory

Page

Memory

Filter

I/O Port

Buffer

Slave

CPU

Modem

Main

CPU

LIF

Laser Diode

Driver

Laser Diode

Copy Paper

Data from the line passes through a filter to remove unwanted frequencies. Then it goes to the modem, which demodulates the data and converts it to parallel.

Reconstruction

From the modem, the data goes to the SAF memory, where it is held in case the printer jams or runs out of paper or toner; after the user corrects the fault, the message will be printed out from the memory and no data will be lost.

The data coming from the modem is compressed data. From the SAF memory, the data passes to the cpu where it is decoded using the line buffer.

1-3-7

Ricoh G3BASIC BASICEUR

CONTENTS

INTRODUCTION

SECTION 1. FAX MACHINE OVERVIEW

1-1. FACSIMILE PROCESS

1-1-2. Thermal Paper Fax Terminals

1. Transmitting

1. Document Feed

2. Exposure

3. Transmission

2. Receiving

1. Reception of Data

2. Paper Feed

3. Printing

4. Cutting

1-1-3. Plain Paper Fax Terminals

1-2. OVERALL SYSTEM CONTROL

1-2-1. Thermal Paper Fax Machines

1-2-2. Plain Paper Fax Machines

1. Serial Interface

2. Parallel Interface

1-3. VIDEO DATA PATH

1-3-1. Transmission

1. Scanning

2. Data Processing

1-3-2. Reception

1. Thermal Printers

2. Laser Printers