Acronym for Video Home System defined by Abbreviationfinder, VHS is a system for recording and reproducing analog audio and video. VHS is physically similar to the audio system (cassette) only, but with the differences that the magnetic tape is much wider (half an inch) and the box or plastic cassette that contains it is larger. The anatomy of a VHS video cassette comprises two internal reels and the tape path (this basic design is used for all audio, video or data cassettes). The opening through which the tape is accessed is protected by a lid that opens automatically by means of a simple mechanism when it is inserted into a VHS player.
It was developed in the 1970s by JVC and released in 1973 by JVC itself and its parent company, Matsushita (Panasonic), along with a broad group of licensees. It came to compete with the then only home system on the market, Sony’s Betamax, also manufactured under license by Sanyo. It managed to become popular and standard for more than fifteen years thanks to a better marketing strategy.
It had a more flexible manufacturing licensing system than Sony’s and they knew better the needs of the users, offering from the beginning a longer recording time, of two hours, compared to only one hour of the first Beta devices. They also made alliances with film distributors (especially the exclusivity of pornographic films). In 1988 Sony admitted defeat and announced the production of a line of VHS recorders. VHS had 95% of the market. The result, VHS would become the standard for the next 10 years.
A VHS cassette can have a maximum of 430 m of tape taking into account an acceptable thickness of it, offering around 3 and a half hours of viewing for the NTSC system and 5 hours for PAL in “standard” quality mode (SP).. Other speeds include LP and EP / SLP that double or triple in duration, for NTSC regions. These slow reproductions cause a slight reduction in video quality (from 250 lines to 230 horizontal analog lines); Also, these types of slow recordings cannot be played back on VHS players that are not equipped with the necessary tape speed technology. That is why normally, video players were marketed only in SP mode.
Both VHS NTSC and PAL / SECAM VHS cassettes are physically identical (although the recording signals on the tape are incompatible). However, since the tape speed differs between NTSC and PAL / SECAM, the playback time between the two systems is slightly different. In order to avoid confusion, manufacturers indicate the duration time in minutes. It is perfectly possible to record and play back a T-XXX cassette on PAL video or an E-XXX cassette on NTSC video, but the length may differ from that indicated. SP is the standard play mode and LP is the long play mode.
Tape reading mechanism
VHS players used a simple mechanism, much like that of audio cassettes, by which the content of the tape is accessed. When a VHS cassette is inserted it is collected in a support that moves it smoothly towards the gears that are responsible for making the tape reels roll.
At the same time, the front protective cover is lifted at its ends by two small handles, exposing the tape and in the middle of the heads located on each side of the cassette, then a tensioner mechanism drives it and adjusts it towards the main head, that quickly turns to the left immediately when the tape is brought to it, while two other heads located near infrared (located on the right and left that are responsible for detecting the transparent tape space, and rewind or fast forward as the case may be), they place the tape in straight positions to make the tape traverse lighter, then a gear slowly advances the tape reel, while the main head reads magnetically (same as a signal TV) sound and video, when recording,A small head emits an electro-magnetic signal that erases the information on the tape and immediately copies the magnetic waves of the signal from TV found on the VHS player’s tuner.