# US 4,400,444 A · Magnetic recording media and process of producing them

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- Number: US 4,400,444 A
- Document ID: US4400444A
- Status: Granted
- Kind: A
- Application number: 06/384,604
- Filed: 1982-06-03
- Granted: 1983-08-23
- Earliest claimed: 1981-06-03
- Assignees: TDK Electronics Co., Ltd.
- Inventors: Toshiaki Izumi; Fumio Maruta; Takayoshi Kobuke; Kiyoshi Noguchi
- Web page: https://patentgrep.com/patent/US4400444A

## CPC

- G11B 5/851: Coating a support with a magnetic layer by sputtering
- H01F 41/20: by evaporation
- Y10S 428/90: Magnetic feature
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A magnetic recording medium having a ferromagnetic layer formed by oblique vapor deposition wherein the residual magnetic flux density in the width direction of the recording medium is larger than the residual magnetic flux density in the longitudinal direction shows the SN ratio in a practical level at recording in the width direction.

## Claims

### Claim 1

A magnetic recording medium comprising a non-magnetic web substrate having at least one ferromagnetic layer formed thereon characterized in that the residual magnetic flux density in the width direction of the web substrate (Br.sub.t) is larger than the residual magnetic flux density in the lengthwise direction thereof (Br.sub.l).

### Claim 2 (depends on 1)

The magnetic recording medium as claimed in claim 1 wherein the Br.sub.t /Br.sub.l ratio is larger than 1.5.

### Claim 3

A process of producing a magnetic recording medium by forming a ferromagnetic layer on a non-magnetic web substrate by a vaccum deposition method characterized in that a cylindrical supporting member for the web substrate is used and the ferromagnetic layer is formed on the web substrate by oblique vapor deposition in the width direction in such a manner that the incident direction of the vapor depositing material is oblique to the direction of the central axis of the supporting member.