4,836,326

43.88.Ja OPTIMAL SHADOW OMNIPHONIC

MICROPHONE AND LOUDSPEAKER SYSTEM

Raymond Wehner, Selkirk, Manitoba, Canada 6 June 1989 (Class 181/144); filed 14 July 1987

This is described as an improvement to the inventor's earlier patent 4,122,910. I have read it three times and cannot comprehend what is being

described and how it is supposed to work.--GLA

4,833,019

43.88.Qg MAGNETIC RECORDING TAPE COMPRISING A SUPPORT FILM HAVING A HIGH

TRANSVERSE DIRECTION MODULUS

Nat. J. Suwarnasarn, assignor to Minnesota Mining and Manufactur- ing Company

23 May 1989 (Class 428/336); filed 17 February 1987

Thin tapes that are more stretchable longitudinally than transversely have been found to make better contact with heads, and also to have better head cleaning capability. Recommended here are tapes 5 to 25 microns thick, with a Young's modulus of 350 Kg/mm 2 in the longitudinal direc- tion, this modulus being 0.3 to 0.5 as much as the modulus in the transverse direction.--MC

4,828,899

43.88.Qg MAGNETIC RECORDING MEDIUM AND RECORDING/REPRODUCING METHOD THEREOF

Hiroyuki Arioka, Masaharu Nishimatsu, and Suguru Takayama, assignors to TDK Corporation

9 May 1989 (Class 428/143); filed in Japan 2 August 1984

The earliest magnetic tapes (40 to 50 years ago) were somewhat abrasive, causing excessive head wear and preventing the good contact necessary for high density recording. Since that time, the tapes have become so smooth that they tend to adhere to the heads, and to clog the head gaps with rubbed- off tape material. The method of this patent ripples the tape surface 16 to

10

prevent perfect head contact by coating the substrate 11 with ultrafine parti- cles of silica 15 prior to applying the magnetic film 12 and lubricant layer 13. The ripples or protrusions are only 30 to 300 Angstroms high (less than a microinch), allowing high density recording.--MC

4,844,978

43.88.Qg MAGNETIC RECORDING MEDIUM

Masatoshi Nakayama, Yasufumi Takasugi, and Kunihiro Ueda, assignors to TDK Corporation

4 July 1989 (Class 428/336); filed in Japan 9 November 1984

Recording tapes having a continuous magnetic layer (instead of magnet- ic particles dispersed in a binder) have superior performance, but their durability is often unsatisfactory. This patent discloses a protective over- layer which is a plasma-polymerized film containing carbon, hydrogen and fluorine, the layer being 10 to 40 Angstroms thick.•MC

4,833,043

43.88.Qg AMORPHOUS MAGNETO OPTICAL RECORDING MEDIUM

Richard N. Gardner, assignor to Minnesota Mining and Manufactur- ing Company

23 May 1989 (Class 428/694); filed 17 May 1983

Magneto-optical recording uses light beams to record, play, and erase a magnetic surface, thereby eliminating the usual sliding heads. An improved magnetic medium is described here that is deposited by a sputtering process to produce an amorphous film such as gadolinium-cobalt having magnetic anisotropy perpendicular to the film surface.•MC

4,835,032

43.88.Qg MAGNETIC RECORDING MEDIUM AND RECORDING/REPRODUCING METHOD THEREFOR

Hiroyuki Arioka, Masaharu Nishimatsu, and Suguru Takayama, assignors to TDK Corporation

30 May 1989 (Class 428/143); filed in Japan 31 July 1984

This is a continuation in part of U.S. Patent 4,828,899 (reviewed above), with the added feature of a back coating containing a pigment, binder, and lubricant. The front coating has protrusions of 30 to 300 Angstroms to prevent adhesion to the head.•MC

4,845,751

43.88.Si WIRELESS STEREO HEADPHONE

Brian H. Schwab, Orlando, FL 4 July 1989 (Class 381/25); filed 16 March 1988

A double headset receives signals from a stereo radio receiver via a radio link. The headset contains, in addition to a radio receiver, a transmitter that allows the wearer to adjust the volume at the stereo receiver, and that also

14

ON-OFF

VOLUME 28

can activate SEEK and SCAN functions at the receiver. Coded signals from the headset transmitter are decoded by a module at the receiver.•SFL

932 J. Acoust. Soc. Am. 87(2), Feb. 1990; 0001-4966/90/02932-01500.80; © 1990 Acoust. Soc. Am.; Patent Reviews 932

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