Magnetic recording disc and method of making same

• US 4,338,643 A
• Filed: 04/08/1980
• Issued: 07/06/1982
• Est. Priority Date: 11/16/1976
• Status: Expired due to Term

• Current Assignee: AU Optronics Corporation
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Tadokoro, Eiichi
• Primary Examiner(s): Wolff, John H.
• Application Number:
  US06/138,368
• Time in Patent Office: 819 Days
• Field of Search: 360/131, 360/133-135
• US Class Current: 360/135
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/852 Orientation in a magnetic field G11B5/845 takes precedence

Abstract

In a method of making a magnetic recording sheet, a magnetic material is applied on a web in a layer consisting of a number of contiguous first strip-like zones and second strip-like zones which are alternately arranged in parallel to each other. The ratio of the width of the first strip-like zone to that of the second strip-like zone is within a range of 1:3 to 3:1. In the first strip-like zones having a width of not more than 5 mm the magnetic particles are oriented in a first direction, and in the second strip-like zones magnetic particles are oriented in a second direction which is inclined with respect to the first direction at an angle from 60° to 120°. With this particular orientation of the magnetic particles in the magnetic layer when the magnetic layer is applied on a web, the orientation of the magnetic particles become almost random while the magnetic layer is hardened. The magnetic recording disc thus prepared has a very low output fluctuation and a higher output level.

Claims

1. A method of producing a magnetic recording disc comprising applying a magnetic layer containing magnetic particles on a support film base, orienting the magnetic particles in a number of first strip-like zones in a first direction and in a number of second strip-like zones in a second direction inclined with respect to the first direction at an angle of 60°

to 120°

, said first and second strip-like zones being alternately and contiguously arranged in parallel to each other, the width of each said first and second strip-like zones being not more than 5 mm and the ratio of the width of the first strip-like zone to that of the second strip-like zone being within the range of 1;

3 to 3;

1, solidifying the magnetic layer after the magnetic particles in said first strip-like zones, causing interaction along the boundaries between adjacent strip-like zones resulting in a random particle orientation and then stamping out a magnetic recording disc from the support film base, whereby positioning of a disc center hole is greatly fascilitated and the output is enhenced.

2. A method of producing a magnetic recording disc as defined in claim 1 wherein the width of each zone is not more than 3 mm.

3. A method of producing a magnetic recording disc as defined in claim 1 wherein said ratio of the widths of the zones is within the range of 1:

2 to 2;

1.

4. A method of producing a magnetic recording disc as defined in claim 1 wherein in said first strip-like zones the magnetic particles are oriented in the longitudinal direction of the zones.

5. A method of producing a magnetic recording disc as defined in claim 4 wherein said second strip-like zones the magnetic particles are oriented in the direction perpendicular to the longitudinal direction of the zones.

6. A magnetic recording disc comprising a circular support film base and a magnetic layer containing magnetic particles carried on a support film base wherein said magnetic layer includes a number of first strip-like zones in which the magnetic particles are oriented in a first direction and a number of second strip-like zones in which the magnetic particles are oriented in a second direction inclined with respect to the first direction at an angle of 60°

to 120°

, said first and second strip-like zones being alternately and contiguously arranged in parallel to each other, the width of each said first and second strip-like zone being not more than 5 mm and the ratio of the width of the first strip-like zone to that of the second strip-like zone being within the range of 1;

3 to 3;

1, the magentic particles at the boundaries formed between said first and second strip-like zones being randomly oriented with said particle orientation resulting in a disc exhibiting improved recording characteristics.

7. A magnetic recording disc as defined in claim 6 wherein the width of each zone is not more than 3 mm.

8. A magnetic recording disc as defined in claim 6 wherein said ratio of the widths of the zones is within the range of 1:

2 to 2;

1.

9. A magnetic recording disc as defined in claim 6 wherein in said first strip-like zones the magnetic particles are oriented in the longitudinal direction of the zones.

10. A magnetic recording disc as defined in claim 9 wherein said second strip-like zones the magnetic particles are oriented in the direction perpendicular to the longitudinal direction of the zones.