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 Sony U-matic cassette | |
| Media type | Magnetic cassette tape, ¾-inch |
|---|---|
| Encoding | NTSC, PAL, SECAM |
| Developed by | Sony |
| Usage | Video production |
| Released | September 1971 Lifespan: September 1971–June 2000 Technical Support 1971–2016 |
U-matic or 3⁄4-inch Type E Helical Scan[1][2] or SMPTE E[3] is an analogue recording videocassette format first shown by Sony in prototype in October 1969, and introduced to the market in September 1971. It was among the first video formats to contain the videotape inside a cassette, as opposed to the various reel-to-reel or open-reel formats of the time. The videotape is 3⁄4 in (19 mm) wide, so the format is often known as "three-quarter-inch" or simply "three-quarter", compared to open reel videotape formats in use, such as 1 in (25 mm) type C videotape and 2 in (51 mm) quadruplex videotape.
Unlike most other cassette-based tape formats, the supply and take-up reels in the cassette turn in opposite directions during playback, fast-forward, and rewind: one reel would run clockwise while the other would run counter-clockwise. A locking mechanism integral to each cassette case secures the tape hubs during transportation to keep the tape wound tightly on the hubs. Once the cassette is taken off the case, the hubs are free to spin. A spring-loaded tape cover door protects the tape from damage; when the cassette is inserted into the VCR, the door is released and is opened, enabling the VCR mechanism to spool the tape around the spinning video drum. Accidental recording is prevented by the absence of a red plastic button fitted to a hole on the bottom surface of the tape; removal of the button disabled recording.
- ^ "ST 21:1997 - SMPTE Standard - For Video Recording — 3/4-in Type E Helical Scan — Records". SMPTE. 1997. Archived from the original on 17 June 2018.
- ^ "ST 22:1997 - SMPTE Standard - For Video Recording — 3/4-in Type E Helical Scan — Cassette". SMPTE. 1997. Archived from the original on 11 June 2018.
- ^ Bentz, Carl (1984). "Broadcast Engineering, November 1984, p. 131" (PDF). Intertec Publishing Corporation.