Magnetic recording and/or reproducing apparatus

4,475,137

43.88.Qg MAGNETIC TRANSDUCER

Isao Yasuda, Yorinobu Yoshisato, Yoshihiko Kawai, and Kazuaki Koyama, assignors to Sanyo Electric Company

2 October 1984 (Class 360/126); filed in Japan 11 May 1981

To record effectively on high coercivity tape such as metal particle tape, a head core Of sendust is advantageous, since it does not saturate at the high fields required. The illustrated head has a central section 4,6 made of

sendust sandwiched between outer sections 22,22 made of ferrite that act as magnetic yokes, surmounted by glass portions 26,26 that reinforce the gap portion 10. The glass material is selected to wear somewhat faster than the central sendust head.mMC

4,491,880

43.88.Qg MAGNETIC RECORDING AND/OR REPRODUCING APPARATUS

Noboru Kojima, Yoshizumi Watatani, Takao Arai, Takashi Hoshino, and Toshifumi Shibuya, assignors to Hitachi, Ltd.

1 January 1985 (Class 360/19.1); filed in Japan 24 September 1981

High quality audio for helical videotape recorders is obtained by allo- cating the end of each helical track to a compressed PCM (pulse code modu- lation) audio signal. The usual helical scanning is with two heads; the tape is wrapped on the head drum to give an overlap where both contact the tape during the changeover from head # 1 to head #2. During the overlap period the head that is leaving the tape is switched briefly to the audio circuits and scans the audio in compressed form. The circuits translate the compressed audio to and from its normal mode.--MC

4,491,890

43.88.Qg DEVICE FOR POSITIONING A MAGNETIC HEAD IN A MAGNETIC TAPE DEVICE

Guttorm Rudi, assignor to Tanberg Data, Oslo, Norway 1 January 1985 (Class 360/106); filed in Germany 31 March 1981

In a cassette recorder the head is moved across the tape to select var- ious tracks by means of spiral gearing connected to a head carrier shaft that slides between two bearings.--MC

4,494,160

43.88.Qg MAGNETIC HEAD AND METHOD OF MANUFACTURING A MAGNETIC HEAD

Jan Bakker, assignor to U.S. Philips Corporation 15 January 1985 (Class 360/129); filed in The Netherlands 11 Decem-

ber 1980

A head for stereo tape recorders is assembled by spot welding tech- niques suitable for economical mass production. Half-cores 17 and 18 are spot welded to a nonmagnetic plate 16, while mating half-cores 30 and 31 are spot welded to a similar plate 19. Gap faces are lapped and plated with gap spacer material; then coils are placed on legs 21 and 21'. A full width

magnetic shield is then inserted between the heads prior to final assembly in a housing containing synthetic resin filler.--MC

4,495,530

43.88.Qg METHOD OF PROCESSING INFORMATION WITH RESPECT TO OPTO-MAGNETIC RECORD MEDIUM

Tuneo Yanagida, assignor to Olympus Optical Company 22 January 1985 (Class 360/$9); filed in Japan 26 November 1980

This is a method for recording on a magnetic disk by use of a laser beam. The disk is first magnetized uniformly in a perpendicular direction and a track is recorded by applying a reverse field together with a modulated laser beam that heats the track locally above its Curie point. This track is erased by saturating it uniformly with the reverse field and an unmodulated laser beam. To rerecord on such a reverse erased track, the external field and modulation polarities are both reversed, thus producing a recording of stan- dard polarity. With the above described procedure, a track is always pres- ent, whether erased or modulated; such a track is necessary to control the laser beam position.--MC

4,503,475

43.88.Qg TAPE CLEANER

Gardner L. Hall, Plymouth, NH $ March 1985 (Class 360/137); filed 8 September 1982

This is a tape cleaning apparatus for cassettes and cartridges. A cas- sette fits on shafts 30,32, with the tape driven by 32 past a pad 28 that cleans,

/15

34 55 30 •6 16

lubricates, and impa•s anQstatic treatment to the c•scttc •. Si•lady, a continuous loop ca.ridge of the stereo-eight-type fits between mcm• S4,SS; its •pe is driven by a capstan • past the cloning pad 26.--MC

826 J. Acaust. Sac. Am. 78(2), August 1985; 0001-4966/85/08826-01500.80; ¸ 1985 Acaust. Sac. Am.; Patent Reviews 826

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