Fax technology was born as early as the 1840s, thirty years before the invention of the telephone!
It was invented in 1843 by a British inventor named Alexander Bain. However, fax communication is a relatively slow-developing technology in the field of telecommunications. It did not gradually mature until the 1920s, and developed rapidly after the 1960s. In the past decade, it has become one of the most widely used communication tools.
The Enlightenment of the Pendulum
The origin of fax technology is very strange. It was not the result of intentionally exploring new means of communication, but was derived from the study of electric clocks. In 1842, Scotsman Alexander Bain studied and produced an electrically controlled pendulum structure, with the purpose of forming a clock in which several clocks were interconnected and synchronized, just like the current master-slave system of mother-child clocks. During the development process, he keenly noticed a phenomenon: the pendulum of every clock in this clock system was in the same relative position at any moment.
This phenomenon led the inventor to think that if the main pendulum could be used to pass through a figure or character composed of electrical contact points during its stroke, then the figure or character would simultaneously move on a remote side of the main pendulum. Or copy it in several locations. Based on this idea, he added a scanning needle to the pendulum, which acted as a brush; and an "information board" driven by the clock. There were graphics or characters to be transmitted on the board, which were composed of electrical contacts. ; There is a piece of electrosensitive paper spread on the receiving end "information board". When the pointer scans on the paper, if there is a current pulse in the pointer, a black spot will appear on the paper. When the pendulum at the transmitting end swings and the pointer touches the contact on the information board, a pulse is emitted. Driven by the clock, the information board slowly moves upward, causing the pointer to scan line by line on the information board, turning the graphics on the information board into electrical pulses and transmitting them to the receiving end; the information board at the receiving end is also driven slowly by the clock. Move, thus leaving a pattern on the electrosensitive paper, forming the same pattern as the sending end. This is a primitive electrochemical recording fax machine.
Roller type fax machine
In 1850, there was another British inventor named F. Becker. He made great improvements to the structure of the fax machine. He used A "roller and screw" device replaced the structure of a clock and pendulum. This improved structure works a bit like a lathe. The drum rotates rapidly, and the artwork sent by fax is rolled on the drum. The scanning needle slowly advances along the axial direction of the drum along the screw rod, spirally scanning the graphics on the surface of the drum. This drum-type fax machine has been in use for more than a hundred years. In 1865, an Iranian named Abakarje developed a practical fax machine based on the fax machine principles and structures proposed by Bain and Bekkal, and took his fax machine to Paris, France. Cities such as Lyon and Marseille conducted experiments with fax communications.
The invention of the photo fax machine
People's requirements for the transmission of news photos and photographic images are very extensive. Many scientists worked on the photo fax machine. On November 8, 1907, a French inventor-Edouard Belland performed his development result-photo fax in front of everyone. Edouard Belland (1876-1963) worked in the French Photography Association building. The French Photography Association building where he was located happened to be the starting point and end point of the French telecommunications line from Paris-Lyon-Bordeaux-Paris. This provides Beland with unique conditions for his research.
Belan's painstaking research obtained permission from the telecommunications department, which allowed him to use this communication line for experiments at night. After three years of research and experimentation in the basement of the building, Beland finally made a photo fax machine. Edward Belland was not satisfied with his initial success and continued research on fax machines. In 1913, he built the world's first portable fax machine for news gathering. In 1914, a French newspaper first published news photos transmitted via fax machine.
Photo fax changes pointer contact scanning to photoelectric scanning, which not only greatly improves the quality of fax, but also enables photo faxing to be realized by the cooperation of photoelectric scanning and photosensitive plate making.
In 1925, the Bell Research Institute of the American Telegraph and Telephone Company developed a high-quality photo fax machine.
In 1926, the wired photo fax service across the continental United States was officially opened. In the same year, the wireless photo fax service across the Atlantic Ocean was also opened with the United Kingdom. Since then, European, American and Japanese countries have successively opened up the photo fax service. Since then, photo fax has been widely used by news agencies to transmit news photos, and later expanded to the military, public security and medical departments, and is used to transmit military photos, maps, criminal photos, Fingerprints, X-ray photos, etc.
Color Fax Machine
The earliest picture of a color fax record was published on the frontispiece of the April 1925 issue of Bell System Technical Report. This picture is actually three separate transmissions of red, green, and blue colors in sequence using color filters, and then overlapped and synthesized. Later, someone used the same basic technology and adopted some automated operations to develop a fax device that could reproduce color pictures. In August 1945, at the Potsdam Conference, color photos of Truman, Stalin and Attlee were successfully transmitted by radio from Europe to Washington. But it still cannot be used to open the color fax service. It was not until the mid-1980s that color fax machines gradually developed to the point where they could be put into practical use.
The great development of fax communication services
In 1968, the United States took the lead in opening fax services on the public telephone network, and countries around the world also used the telephone network to open fax communication services. The number of fax machines that were originally limited to dedicated circuit applications has increased sharply, and the scope of applications has rapidly expanded. In particular, document fax machines, which are used to transmit handwritten, typed or printed letters, documents, forms, graphics, etc., are the most commonly used and are developing the fastest. The original International Telephone Consultative Committee (CCITT) classified document fax machines used on the telephone network. They are:
The production standards implemented by fax machines currently and once sold on the market:
One Category 1 machine (G1): It takes about 6 minutes to transmit one page of A4 format (210mm & #215;296mm) document on the phone line;
Category 2 machine (G2): It takes about 6 minutes to transmit one page of A4 format document on the phone line. , it takes about 3 minutes;
Category 3 machine (G3): It takes about 1 minute to transmit a page of A4 format document on the phone line;
Category 4 machine (G4): High speed The document fax machine can send one page of A4 format document in just 3 seconds.
Before the 1970s, Category 1 machines were mainly used. In the 1970s, Category 2 machines were used. In the 1980s, Category 3 machines began to be popularized. Its performance and functions have been continuously improved, and it has gradually become the most popular method for fax communication. Main models. The use of Category 4 machines is not yet widespread.
In the past ten years or so, fax communication has developed more rapidly and has become one of the fastest growing non-telephone telecommunications services.
We often see words such as "Xinhua News Agency Faxed Photos" in newspapers, which indicates that the photos were taken by Xinhua News Agency reporters in foreign countries or outside the country and sent back by fax machine. . If there was no fax machine and we relied solely on postal transportation, it would take as fast as three to five days or as slowly as half a month. At that time, the news published in newspapers would become "old news."
The history of fax machines is no later than that of telegraph machines. As early as 1843, before Morse's first telegraph line was built, Scottish electrical engineer Alexander. Bain invented the first fax machine. Bain's fax machine used an electromagnetic excitation pendulum for scanning. A brush was installed on the top of the pendulum. By swinging the pendulum back and forth, it scanned out the words written in metal on the transmitting desk. When receiving, the metal brush is scanned on the paper soaked in starch solution, and a colored record is produced through chemical reaction. In 1848, Bakewell further developed Bain's fax technology. His most outstanding contribution was the invention of barrel scanning technology, which is still in use today. In 1857, Frenchman Kesley conducted fax communication experiments between Paris and Lyon and Paris and Marseille. The content of the experiment was the transmission of photos.
In the more than half a century since then, there has been no major progress in fax technology. The reason is that some key components, such as photoelectric conversion components and signal amplification components, are not yet available or are very imperfect. It was not until triodes, photoelectric tubes, and Nixie tubes were developed that fax machines truly left the laboratory and entered the practical stage. In 1925, AT&T's Bell Laboratories developed a practical fax machine using vacuum tube technology and photoelectric tube technology, and launched a wired photo fax service across the American continent the following year.
The principle of Bell Labs' fax machine is this: the sending end rolls the sent image on the roller of the fax machine, and the roller rotates while moving laterally, and the light spot scans back and forth on the image line by line. And covers the entire screen, so that the image is broken down into several consecutive small dots. The light spot shines on different parts of the image and reflects light of different strengths and weaknesses. The reflected light is received by the photoelectric tube and converted into electrical signals of different strengths and weaknesses, and then modulated and amplified and sent to the transmission line. The receiving end plays the role of synthesizing images. After the input signal is amplified and demodulated, it is added to the Nixie tube and then converted into light spots of different strengths and weaknesses. There is also a roller on the receiver, and the rotation and movement of the roller are synchronized with the transmitter. The cylinder is equipped with photosensitive recording paper, and the light points converted by the Nixie tube are irradiated on the photosensitive paper. Due to the synchronous rotation and movement of the drum, the recording paper is exposed to light point by point and line by line, and a fax image similar to the sent image is formed.
The role of the fax machine was fully demonstrated in World War II. Newspaper offices rushed to use fax technology to deliver news photos, so that people at the rear could see the fighting situation of soldiers at the front in a timely manner. Therefore, after World War II, fax technology entered an era of rapid development.
In layman’s terms, a fax machine is a “remote copy.” The current development trend of fax machines is: the transmission speed is getting faster and faster, the transmitted images are getting clearer and clearer, the operation method is getting simpler and simpler, and the equipment is getting smaller and smaller.