Method and apparatus for manufacturing magnetic recording medium

• US 6,261,647 B1
• Filed: 01/25/1996
• Issued: 07/17/2001
• Est. Priority Date: 02/01/1995
• Status: Expired due to Fees

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Shibata, Norio, Komatsu, Kazunori
• Primary Examiner(s): PIANALTO, BERNARD D
• Application Number:
  US08/591,037
• Time in Patent Office: 2,000 Days
• Field of Search: 427/548, 427/549, 427/550, 427/599, 427/128-132
• US Class Current: 427/549
• CPC Class Codes: G11B 5/845 in a magnetic field

Abstract

A method for manufacturing a magnetic recording medium includes steps of forming a magnetic layer containing magnetic powder particles on a web-like non-magnetic support being continuously transported in one direction and applying a magnetic field to the magnetic layer by a plurality of magnets in such a manner that an angle of the magnetic field applied to the magnetic layer to the transporting direction of the non-magnetic support in a plane perpendicular to a surface of the magnetic layer and parallel to the transporting direction of the non-magnetic support gradually increases in the transporting direction of the non-magnetic support, thereby orienting the magnetic powder particles in an oblique direction with respect to the surface of the magnetic layer. According to this method, it is possible to orient magnetic powder particles in a desired direction with respect to the surface of a magnetic layer and to manufacture a magnetic recording medium having a high squareness ratio without increasing the size of the apparatus.

Claims

1. A method for manufacturing a magnetic recording medium comprising;

a. forming at least one magnetic layer containing magnetic powder particles on a web-like non-magnetic support;

b. transporting the non-magnetic support in a transport direction;

c. applying a first magnetic field to the magnetic layer in a plane that is perpendicular to a surface of the magnetic layer;

d. applying a second magnetic field to the magnetic layer in a plane that is parallel to the surface of the magnetic layer by providing a fixed electric current to each of a plurality of electromagnets arranged in the transport direction;

wherein an angle of a magnetic field formed by the first and second magnetic field with respect to the transport direction only gradually increases as the non-magnetic support is transported in the transport direction so that an orientation of the magnetic powder particles is increased in an oblique direction with respect to the surface of the magnetic layer as the non-magnetic support is transported.

2. The method of claim 1 wherein the magnetic powder particles are oriented in the oblique direction by the second magnetic field after they have been once oriented in the transport direction.

3. The method of claim 2 wherein the magnetic powder particles are oriented while the magnetic layer is being dried.

4. The method of claim 1 wherein the magnetic powder particles are oriented while the magnetic layer is being dried.

5. In apparatus for manufacturing a magnetic recording medium comprising:

a. at least one first magnet for generating a first magnetic field perpendicular to a surface of at least one magnetic layer formed on a non-magnetic support and containing magnetic powder particles;

b. a plurality of second magnets for generating a second magnetic field parallel to the surface of the magnetic layer;

c. an electric current source to supply a fixed value to each of the second magnets before the non-magnetic support is introduced to the second magnetic field wherein the second magnetic field decreases gradually in strength from one end of the first magnetic field to the other end so that an orientation of the magnetic powder particles is increased in an oblique direction with respect to the surface of the magnetic layer as the non-magnetic support is being transported.

6. The apparatus of claim 5 wherein the second magnets are provided with an extended portion extending from the one end in a direction away from the other end.

7. The apparatus of claim 6 further comprising a drier wherein the magnetic powder particles are oriented while being dried.

8. The apparatus of claim 6 wherein the first magnet includes permanent magnets disposed so that opposite poles thereof face each other and wherein the second magnets includes at least two solenoid coils.

9. The apparatus of claim 6 wherein a resulting magnetic field formed by the first and second magnetic field has an angle that only gradually increases with regard to the transport direction.

10. The apparatus of claim 5 further comprising a drier wherein the magnetic powder particles are oriented while being dried.

11. The apparatus of claim 5 wherein the first magnet includes permanent magnets disposed so that opposite poles thereof face each other and wherein the second magnets includes at least two solenoid coils.

12. A method for manufacturing a magnetic recording medium comprising the steps of:

a. forming at least one magnetic layer containing magnetic powder particles on a web-like non-magnetic support

b. transporting the non-magnetic support in a transport direction; and

,

c. applying a magnetic field to the magnetic layer by a plurality of magnets wherein the field has two components with a first component of the field being in a plane that is perpendicular to a surface of the magnetic layer and a second component of the field being in a plane that is parallel to the transport direction in which the strength of the magnetic field in the transport direction is controlled between a coercive force of magnetic powder particles in the non-magnetic support and approximately 100000 Oe, wherein an electric current for each of the plurality of magnets of the second component of the field is controlled to a fixed value respectively before applying the magnetic field to the non-magnetic support such that an angle of the magnetic field with respect to the transport direction only gradually increases by controlling electrical current supplied to the solenoid coils as the non-magnetic support is transported in the transport direction, thereby orienting the magnetic powder particles in an oblique direction with respect to the surface of the magnetic layer.