How does a fax machine receive faxes?

Working principle:

Common fax machines in the market can be divided into four categories:

1. Thermal paper fax machines (also known as web fax machines);

thermal paper fax machine (also called web fax machine): thermal paper fax machine melts and discolors the thermal materials on the printing medium through the thermal print head to generate the required text and graphics.

thermal transfer is developed from thermal technology. By adding a thermal transfer ribbon, the ink coated on the ribbon is transferred to paper to form an image. Thermal printing is used in the most common fax machines.

2. Laser plain paper fax machine (also called laser all-in-one machine);

Laser plain paper fax machine (also called laser all-in-one machine): The laser plain paper fax machine is a fax machine that uses toner to attach to paper to form images.

its working principle is mainly to use a selenium drum in the machine body to control the laser beam, and by controlling the laser beam to turn on and off, a charged image area is generated in the selenium drum. At this time, the toner in the fax machine will be attracted by the charge and attached to the paper to form characters or images.

3. Ink-jet plain paper fax machine (also known as ink-jet integrated machine);

Ink-jet plain paper fax machine (also known as ink-jet all-in-one machine): The working principle of ink-jet fax machine is similar to dot matrix printing. The ink-jet head is driven by a stepping motor to move left and right, and the ink ejected from the ink-jet head is sprayed on plain paper in sequence to finish printing.

4. Thermal transfer plain paper fax machine:

The working principle of fax machine is very simple, that is, the document to be sent is scanned and converted into a series of black and white dot information, which is then converted into audio signals and transmitted through traditional telephone lines.

after the receiver's fax machine "hears" the signal, it will print out the corresponding point information, so that the receiver will receive a copy of the original sent document. However, the printing methods of the four fax machines are different after receiving the signal, and their working principles are basically different in these aspects.

Extended data

The fax machine decomposes the original to be sent into

many tiny units (called pixels) by the optical scanning system according to the specified order, and then converts the brightness information of these tiny units into electrical signals by photoelectric conversion devices in sequence, and sends them to the channel after amplification, coding or modulation. After amplifying, decoding or demodulating the received signal, the receiver copies the original in the form of recording at the same scanning speed and order as the transmitter.

according to its transmission color, fax machines can be divided into black-and-white fax machines and narrow-band fax machines (occupying one session frequency band) and broadband fax machines (occupying 12 sessions, 6 sessions or a wider frequency band).

according to different transmission speeds and modulation methods, document fax machines occupying one session can be divided into the following categories:

① A machine with double-sideband modulation technology and a transmission speed of about 6 minutes per page (16 switches) is called a first-class machine;

② a machine with frequency band compression technology and a transmission speed of about 3 minutes per page is called a second-class machine;

③ A computer with a transmission speed of about 1 minute per page using digital processing technology to reduce the redundancy of information sources is called Class III computer;

④ fax machines that can be connected to the computer, can store information and have a transmission speed close to real time are classified as four types of machines. According to the purpose, it can be divided into weather map fax machine, photo fax machine, document fax machine, newspaper fax machine and so on. Recording methods include electrolysis, electromagnetism, cauterization, photography, thermal and electrostatic recording, etc.

resources

Baidu encyclopedia-fax machine