15 June 2016

Videocassette recorder



The invention:

 A device for recording and playing back movies
and television programs, the videocassette recorder (VCR) revolutionized
the home entertainment industry in the late 1970’s.


The company behind the invention:

Philips Corporation, a Dutch Company





Videotape Recording

Although television sets first came on the market before World
War II, video recording on magnetic tape was not developed until
the 1950’s. Ampex marketed the first practical videotape recorder
in 1956. Unlike television, which manufacturers aimed at retail
consumers from its inception, videotape recording was never expected
to be attractive to the individual consumer. The first videotape
recorders were meant for use within the television industry.
Developed not long after the invention of magnetic tape recording
of audio signals, the early videotape recorders were large machines
that employed an open reel-to-reel tape drive similar to that
of a conventional audiotape recorder. Recording and playback heads
scanned the tape longitudinally (lengthwise). Because video signals
have a much wider frequency (“frequency” is the distance between
the tops and the bottoms of the signal waves) than audio signals do,
this scanning technique meant that the amount of recording time
available on one reel of tape was extremely limited. In addition,
open reels were large and awkward, and the magnetic tape itself
was quite expensive.
Still, within the limited application area of commercial television,
videotape recording had its uses. It made it possible to play
back recorded material immediately rather than having to wait for
film to be processed in a laboratory. As television became more popular
and production schedules became more hectic, with more material
being produced in shorter and shorter periods of time, videotape
solved some significant problems.



Helical Scanning Breakthrough


Engineers in the television industry continued to search for innovations
and improvements in videotape recording following
Ampex’s marketing of the first practical videotape recorder in the
1950’s. It took more than ten years, however, for the next major
breakthrough to occur. The innovation that proved to be the key to
reducing the size and awkwardness of video recording equipment
came in 1967 with the invention by the Philips Corporation of helical
scanning.
All videocassette recorders eventually employed multiple-head
helical scanning systems. In a helical scanning system, the record
and playback heads are attached to a spinning drum or head that rotates
at exactly 1,800 revolutions per minute, or 30 revolutions per
second. This is the number of video frames per second used in the
NTSC-TV broadcasts in the United States and Canada. The heads
are mounted in pairs 180 degrees apart on the drum. Two fields on
the tape are scanned for each revolution of the drum. Perhaps the
easiest way to understand the helical scanning system is to visualize
the spiral path followed by the stripes on a barber’s pole.
Helical scanning deviated sharply from designs based on audio
recording systems. In an audiotape recorder, the tape passes over
stationary playback and record heads; in a videocassette recorder,
both the heads and the tape move. Helical scanning is, however, one
of the few things that competing models and formats of videocassette
recorders have in common. Different models employ different
tape delivery systems and, in the case of competing formats such as
Beta and VHS, there may be differences in the composition of the
video signal to be recorded. Beta uses a 688-kilohertz (kHz) frequency,
while VHS employs a frequency of 629 kHz. This difference
in frequency is what allows Beta videocassette recorders (VCRs) to
provide more lines of resolution and thus a superior picture quality;
VHS provides 240 lines of resolution, while Beta has 400. (For this
reason, it is perhaps unfortunate that the VHS format eventually
dominated the market.)
In addition to helical scanning, Philips introduced another innovation:
the videocassette. Existing videotape recorders employed a
reel-to-reel tape drive, as do videocassettes, but videocassettes en-
close the tape reels in a protective case. The case prevents the tape
from being damaged in handling.
The first VCRs were large and awkward compared to later models.
Industry analysts still thought that the commercial television
and film industries would be the primary markets for VCRs. The
first videocassettes employed wide—3
4-inch or 1-inch—videotapes,
and the machines themselves were cumbersome. Although Philips
introduced a VCR in 1970, it took until 1972 before the machines actually
became available for purchase, and it would be another ten
years before VCRs became common appliances in homes.


Consequences


Following the introduction of the VCR in 1970, the home entertainment
industry changed radically. Although the industry did not
originally anticipate that the VCR would have great commercial potential
as a home entertainment device, it quickly became obvious
that it did. By the late 1970’s, the size of the cassette had been reduced
and the length of recording time available per cassette had
been increased from one hour to six. VCRs became so widespread
that advertisers on television became concerned with a phenomenon
known as “timeshifting,” which refers to viewers setting the
VCR to record programs for later viewing. Jokes about the complexity
of programming VCRs appeared in the popular culture, and an
inability to cope with the VCR came to be seen as evidence of technological
illiteracy.
Consumer demand for VCRs was so great that, by the late 1980’s,
compact portable video cameras became widely available. The same
technology—helical scanning with multiple heads—was successfully
miniaturized, and “camcorders” were developed that were not much
larger than a paperback book. By the early 1990’s, “reality television”—
that is, television shows based on actual events—began relying
on video recordings supplied by viewers rather than material
produced by professionals. The video recorder had completed a circle:
It began as a tool intended for use in the television studio, and it
returned there four decades later. Along the way, it had an effect no
one could have predicted; passive viewers in the audience had evolved
into active participants in the production process.


See also :
Cassette recording; Color television; Compact disc;
Dolby noise reduction; Television.