3,984,874

43.88.Qg HIGH DENSITY MAGNETIC RECORDING AND REPRODUCING SYSTEM

Yujiro Mano, assignor to TDK Electronic Company $ October 1976 (Class 360/119);filed 18 November 1974

This patent proposes that the tape should be magnetized in a transverse direction rather than in the usual longitudinal direction. For this purpose the head is turned 90 ø in its azimuth angle, its gap is enlarged, and its width is reduced to the micron range. No experi- mental data is given to show that higher density indeed is available, or to contradict the general opinion that longitudinal recording gives higher densities than other modes.-MC

4,093,885

43.88.Qg TRANSDUCER ASSEMBLY VIBRATION SENSOR

David Edward Brown, assignor to Ampex Corporation 6 June 1978 (Class 310/331); filed 16 April 1976

The magnetic playback head is mounted on a piezoelectric ele- ment which is capable of shifting the head automatically to keep it aligned with a narrow recorded track. An additional piezoelectric element senses the head deflection and operates a servo system that prevents undesired vibrations of the first element.-MC

4,086,445

43.88.Si TELEPHONE HANDSET TRANSMITTER WITH

IMPROVED OUTPUT RESPONSE

3,986,206

43.88.Qg MAGNETIC RECORDING MEDIUM WITH HIGHLY ANISOTROPIC PARTICLES

Richard E. Fayling, assignor to Minnesota Mining and Manufacturing Company

12 October 1976 (Class 360/2); fried 27 January 1975

A magnetic record is made of anisotropic high coercivity material that can be recorded in its easy direction, but which resists erasure in the hard directions. Such records can be used for credit cards

that are validated after passing through a magnetic field strong enough to erase ordinary recording materials.-MC

Ronald Charles Robinson, assignor to Northern Telecom Limited

25 April 1978 (Class 179/121 R); filed 21 January 1977

This patent describes step by step some acoustical modifications to a standard carbon transmitter by which a significant increase in output is derived in the midrange region centering around 1500 Hz. The modification comprises altering the acoustic resistance in the acoustic path between the front and rear surfaces of the diaphragm. The net result is to change the frequency characteristic from a rising to a generally flat curve in the 1-5 KHz range. The advisability of this characteristic may not have been established.-RWC

4,087,633

43.85.Si DEREVERBATION SYSTEM

3,986,209

43.88.Qg MAGNETIC READ HEAD WITH OFFSET FLUX GAPS

Harold James Beecroft, Thomas Francis Burneice, III, Douglas Joseph Hennenfent, assignors to Control Data Corporation

12 October 1976 (Class 360/121); filed 19 May 1975

Data recorders use discs with a high density of adjacent tracks. The discs also have special channels with prerecorded servo signals and with a servo pickup head that corrects the head positioning when it sense any unbalance in tracking. A servo pickup head is disclosed here with two elements spaced apart by a fractional servo channel width. By choosing one or the other as the active locking element a larger number of positions can be selected than the number of servo channels.-MC

James William Fitzwilliam, assignor to Bell Telephone Laboratories, Incorporated

2 May 1978 (Class 179/1 P); filed 18 July 1977

This patent provides a review of several circuit systems for suppressing the effect of reverberation on desired signal pickup. There is described a new combination of some of the prior circuit systems which improved suppression of undesired reverberation. -RWC

4,096,439

43.88.Si AMPLIFIED MICROPHONE ASSEMBLY

Peter A. Hochstein, Sterling Heights, Michigan 20 June 1978 (Class 325/21); filed 27 December 1976

This patent describes the combination of a microphone, an amplifier utilizing rechargable batteries, and means for recharging the batteries by the use of auxiliary contacts on the common push-to-talk switch.-RWC

4,091,158

43.88.Qg MAGNETIC RECORDING MEMBERS

Akira Kasuga, Goro Akashi, Osamu Suzuki, assignors to Fuji Photo Film Company, Limited

23 May 1978 (Class 428/216). filed 12 April 1976

This tape for magnetic recording is coated with two magnetic layers, the undercoating being the usual gamma ferric oxide, and the upper coating being a fine thin layer of ferromagnetic iron oxide which has been specially heat treated to reduce its "average pore population" to about 1.0 and to increase its coercivity to 300 to 500 Oersteds.-MC

4,101,735

43.88.Si TWO-WAY LOUDSPEAKING DEVICE FOR

TELEPHONE STATIONS '

Edwin Redmond Bridenbaugh, assignor to International Telephone and Telegraph Corporation

18 July 1978 (Class 179/1 HF); filed 21 March 1977

Like almost all other loudspeaking telephone designs the inven- tion uses voice-operated send/receive switching, since this is about the only way to get sufficient gain without oscillation. The inven- tion utilizes a single transducer for both send and receive functions. Associated circuitry is especially suited to call announcing key systems in that the called party can reply without picking up his telephone or operating any controls.-GLA

1096 J. Acoust. Soc. Am. 65(4), Apr. 1979; 0001-4966/79/041096-01500.80; ¸ 1979 Acoust. Soc. Am.; Patent Reviews 1096

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