Video tape recorder

An agreement by Japanese manufacturers on a common standard recording format, which allowed cassettes recorded on one manufacturer's machine to play on another's, made a consumer market possible; and the first consumer videocassette recorder, which used the U-matic format, was introduced by Sony in 1971.^[1]

History[edit]

In early 1951, Bing Crosby asked his Chief Engineer John T. (Jack) Mullin if television could be recorded on tape as was the case for audio. Mullin said that he thought that it could be done. Bing asked Ampex to build one and also set up a laboratory for Mullin in Bing Crosby Enterprises (BCE) to build one.^[2] In 1951 it was believed that if the tape was run at a very high speed it could provide the necessary bandwidth to record the video signal. The problem was that a video signal has a much wider bandwidth than an audio signal does (6 MHz vs 20 kHz), requiring extremely high tape speeds to record it. However, there was another problem: the magnetic head design would not permit bandwidths over 1 megahertz to be recorded regardless of the tape speed.


The first efforts at video recording, using recorders similar to audio recorders with fixed heads, were unsuccessful. The first such demonstration of this technique was done by BCE on 11 November 1951. The result was a very poor picture. Another of the early efforts was the Vision Electronic Recording Apparatus, a high-speed multi-track machine developed by the BBC in 1952.^[3] This machine used a thin steel tape on a 21-inch (53.5 cm) reel traveling at over 200 inches (510 cm) per second. Despite 10 years of research and improvements, it was never widely used due to the immense length of tape required for each minute of recorded video.


By 1952 BCE also had moved on to multi-track machines, but found limitations in recording bandwidth even at the high speeds. In 1953 BCE discovered that the magnetic head design was the problem. This problem was corrected and bandwidths exceeding the 1 megahertz limit were able to be recorded.^[2] Since BCE and AMPEX were working together on the video recorder the new head design was shared with them, and AMPEX used it in their recorder. In 1955 BCE demonstrated a broadcast-quality color recorder that operated at 100 inches per second and CBS ordered three of them. Many other fixed-head recording systems were tried but all required an impractically high tape speed. It became clear that practical video recording technology depended on finding some way of recording the wide-bandwidth video signal without the high tape speed required by linear-scan machines.


In 1953 Eduard Schüller of Telefunken patented the helical scan technology. Another solution was transverse-scan technology, developed by Ampex around 1954, in which the recording heads are mounted on a spinning drum and record tracks in the transverse direction, across the tape. By recording on the full width of the tape rather than just a narrow track down the center, this technique achieved a much higher density of data per linear centimeter of tape, allowing a lower tape speed of 15 inches per second to be used. The Ampex VRX-1000 became the world's first commercially successful videotape recorder in 1956. It uses the 2″ quadruplex format, using two-inch (5.1 cm) tape.^[4] Because of its US$50,000 price, the Ampex VRX-1000 could be afforded only by the television networks and the largest individual stations.^[5]


By early 1957 the only successful manufacturer of videotape was 3M, the product being exceedingly difficult to manufacture to the necessary quality. The three U.S. networks officially inaugurated use of videotape on 28 April 1957, "with the changeover to daylight saving time," at which time there were "probably not more than 50 useable rolls of tape among them—it was that critical."^[6]


Ampex's quadruplex magnetic tape video recording system has certain limitations, such as the lack of clean pause, or still-frame, capability, because when tape motion is stopped, only a single segment of the picture recording is present at the playback heads (only 16 lines of the picture in each segment), so it can only reproduce recognizable pictures when the tape is playing at normal speed.^[7]) But in spite of its drawbacks it remained the broadcasting studio standard until about 1980. The helical scan system overcame this limitation.^[8]


In 1959 JVC demonstrated its first helical scan VTR named KV-1.^[9] In 1963, Philips introduced its EL3400 1" helical scan recorder (aimed at the business and domestic user), and Sony marketed the 2" PV-100, its first open-reel VTR intended for business, medical, airline, and educational use.^[10]


The Telcan, produced by the Nottingham Electronic Valve Company and demonstrated on June 24, 1963,^[11] was the first home video recorder. It could be bought as a unit or in kit form for £60. However, there were several drawbacks: it was expensive, not easy to put together, and can record for only 20 minutes at a time in black-and-white.^[12][13][14]


The Sony model CV-2000, first marketed in 1965, is their first VTR intended for home use and is based on half-inch tape.^[15] Ampex and RCA followed in 1965 with their own open-reel monochrome VTRs priced under US $1,000 for the home consumer market. Prerecorded videos for home replay became available in 1967.^[16]


The EIAJ format is a standard half-inch format used by various manufacturers. EIAJ-1 is an open-reel format. EIAJ-2 uses a cartridge that contains a supply reel, but not the take-up reel. Since the take-up reel is part of the recorder, the tape has to be fully rewound before removing the cartridge, which is a relatively slow procedure.


The development of the videocassette followed other replacements of open-reel systems with a cassette or cartridge in consumer items: the Stereo-Pak 4-track audio cartridge in 1962, the compact audio cassette and Instamatic film cartridge in 1963, the 8-track cartridge in 1965, and the Super 8 home motion picture film cartridge in 1966. Before the invention of the video tape recorder, live video was recorded onto motion picture film stock in a process known as telerecording or kinescoping. Although the first quadruplex VTRs recorded with good quality, the recordings could not be slowed or freeze-framed, so kinescoping processes continued to be used for about a decade after the development of the first VTRs.

Video tape recorder technologies include: