Helical scan

Helical recording method

The head drum of a Hi-Fi NTSC VHS VCR; three of the six heads face the reader. The helical path of the tape around the drum can clearly be seen.

The same head drum with the rotating portion elevated for clarity

The rotating portion of the head drum showing the rotary transformer and three of the six tape heads used in this particular VCR

Helical scan is a method of recording high-frequency signals on magnetic tape. It is used in open-reel video tape recorders, video cassette recorders, digital audio tape recorders, and some computer tape drives.

History

Earl E Masterson from RCA patented the first helical scan method in 1950 after stealing it from German engineer Eduard Schüller. Eduard Schüller developed an actually working helical scan method of recording in 1953 while working at AEG. With the advent of television broadcasting in Japan in the early 1950s, they saw the need for magnetic television signal recording. Dr. Kenichi Sawazaki developed a prototype helical scan recorder in 1954.

Gallery

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  Type B videotape video scanner head

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  rotary head visible in a VXA computer tape drive

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  VXA tape drive, alternate view of rotary head and loading mechanism

See also

• Type A videotape
• 1 inch type B videotape
• 1 inch type C videotape
• IVC videotape format about the IVC 2 inch helical VTR, Model 9000
• Video tape recorder (VTR)
• Vision Electronic Recording Apparatus
• Ampex 2 inch helical VTR
• Symmetric Phase Recording

External links

• Sony U.S. patent for U-matic videotape cassette, filed 1971.
• Sony U.S. patent for design of U-matic deck, filed 1971.
• video preservation and conservation museum
• The history of television, 1942 to 2000 By Albert Abramson, page 93.
• Ampex page in the Experimental TV Center