MAGNETIC MEMORY MEMBERS AND METHODS OF MAKING THE SAME

• US 3,607,528 A
• Filed: 02/08/1968
• Issued: 09/21/1971
• Est. Priority Date: 02/08/1968
• Status: Expired due to Term

• Current Assignee: James S. Gassaway
• Original Assignee: James S. Gassaway
• Inventors: Gassaway, James S.
• Primary Examiner(s): Sebastian, Leland A.
• Application Number:
  US04/704,031
• Time in Patent Office: 1,321 Days
• Field of Search: 156/230,245,289,295 179/1.2A 252/62.54 264/104 274/41.4
• US Class Current: 156/230
• CPC Class Codes: C09D 5/23 Magnetisable or magnetic paints or lacquers
• CPC Class Codes: G11B 5/68 comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
• CPC Class Codes: G11B 5/84 Processes or apparatus specially adapted for manufacturing record carriers
• CPC Class Codes: G11C 11/06 using single-aperture storage elements, e.g. ring core; using multi-aperture plates in which each individual aperture forms a storage element
• CPC Class Codes: G11C 11/14 using thin-film elements
• CPC Class Codes: Y10S 428/90 Magnetic feature

Abstract

A magnetic memory member produced by providing a master member of glass, or the like, having a predetermined finished surface to which a very thin silver or other parting agent may be applied, a magnetic coating of a desired thickness being applied to the parting agent, which coating may, for example, be magnetic particles in a binder or magnetic material plated directly on the parting agent, the magnetic coating assuming the same surface condition as the master member. A substrate is secured to the magnetic coating, the parting agent released from the master member and the parting agent removed from the coating. Where the magnetic coating includes a binder with magnetic particles therewithin, the magnetic memory member so produced has a dense film of magnetic particles concentrated at the outer surface of the coating for subsequent coaction with a recording or reproducing head.

Claims

2. A method as defined in claim 1;

said coating being bonded to said substrate by applying an intervening bonding agent to said coating and substrate.

3. A method as defined in claim 1;

wherein said surface is smooth and flat and said substrate is of disc form to produce a disc magnetic memory member.

4. A method as defined in claim 1;

wherein said substrate and master member are made of materials having different coefficients of expansion, the temperature of said substrate and master member being changed to release said coating from said master member without effecting release of said coating from said substrate.

5. A method as defined in claim 1;

wherein said coating comprises a parting agent applied to said surface, said magnetic memory means being applied to said parting agent.

6. A method as defined in claim 1;

wherein said coating further comprises a minor amount of a lubricant to permit releasable contact of said coating against said surface.

7. A method as defined in claim 1;

wherein said magnetic memory means is a magnetic plating.

8. A method as defined in claim 1;

wherein said magnetic memory means is a magnetic plating;

said coating being bonded to said substrate by applying an intervening bonding agent directly to said magnetic plating and substrate.

9. A method of making a magnetic memory member comprising providing two rigid master members, each having a nonundulant surface corresponding to a desired surface of said memory member, applying a coating comprising magnetic memory means to the surface of each master member, placing a rigid substrate between the opposed coated surfaces of said master members, bonding said coatings to opposite sides of said substrate, and then releasing said coatings from said master members.

10. A method as defined in claim 9;

wherein said magnetic memory means of each coating is a magnetic plating.

11. A method as defined in claim 9;

each of said coatings being bonded to said substrate by applying an intervening hardenable bonding agent to said coating and substrate.

12. The method of making a magnetic memory member comprising providing a rigid master member having a nonundulant surface thereon corresponding to the desired surface of the memory member, applying a coating comprising a dispersion including magnetic particles to said surface, placing rigid substrate against said coating, hardening said coating and bonding said coating to said substrate, and then releasing said hardened coating from said surface of said master member.

13. A method as defined in claim 12;

wherein said surface is smooth and flat and said substrate is of disc form to produce a disc magnetic memory member.

14. A method as defined in claim 12;

wherein said dispersion includes a mixture of magnetic particles and a binder, said dispersion being hardened and bonded to said substrate by heating said dispersion.

15. A method as defined in claim 12;

wherein said dispersion includes a mixture of magnetic particles and a binder, said dispersion being hardened and bonded to said substrate by heating said coating, substrate and master member, said master member and substrate having different coefficients of expansion, whereby cooling of said hardened coating, substrate and master member releases said master member from said coating without releasing said dispersion from said substrate.

16. A method as defined in claim 12;

wherein said magnetic particles are concentrated in said dispersion contiguous said surface preparatory to hardening of said dispersion.

17. A method as defined in claim 12;

wherein said surface is smooth and flat, said substrate being of disc form to produce a disc magnetic memory member, said master member being below said coating to permit said magnetic particles to gravitate in said dispersion toward said surface to provide a concentration of particles contiguous said surface preparatory to hardening of said dispersion.

18. A method of making a magnetic memory member comprising providing a rigid master member having a nonundulant surface thereon corresponding to the desired surface of the memory member, depositing a parting agent on said surface, coating said parting agent with a mixture of magnetic particles and a binder, placing a rigid substrate against said mixture, hardening said mixture and bonding said mixture to said substrate, and then releasing said parting agent from said master member surface.

19. A method as defined in claim 18;

wherein said surface is smooth and flat and said substrate is of disc form to produce a disc magnetic memory member.

20. A method as defined in claim 18;

wherein said mixture is hardened and bonded to said substrate by heating said mixture, substrate, parting agent and master member, said master member and substrate having different coefficients of expansion whereby cooling of said hardened mixture, substrate, parting agent and master member releases said parting agent from said master member surface.

21. A method of making a magnetic memory member comprising providing two master members, each having a surface thereon corresponding to a desired surface of said memory member, applying a coating comprising a dispersion including magnetic particles to the surface of each master member, placing substrate between the opposed coated surfaces of said master members, retaining said opposed surfaces a predetermined distance apart, hardening said dispersions and bonding said dispersions to the opposite sides of said substrate, and then releasing said master members from said coatings.

22. A method as defined in claim 21;

at least partially hardening said dispersions preparatory to placing said substrate between the opposed coated surfaces of said master members, applying a binder to each of said at least partially hardened dispersions, then placing the substrate between the opposed coated surfaces of said master members with said binders being bonded to the opposite sides of said substrate.

23. A method of making a magnetic memory member comprising providing two master members, each having a surface thereon corresponding to a desired surface of said memory member, depositing a parting agent on said surface of each of said master members, coating each parting agent with a mixture of magnetic particles and a binder, placing a substrate between the opposed coated surfaces of said master members, placing spacer means between said master members in engagement with uncoated areas of said parting agent to determine the overall thickness of said memory member, hardening said mixtures and bonding said coatings to the opposite sides of said substrate, and then releasing said master member surfaces from said parting agents.

24. The method of making a magnetic memory member comprising providing a rigid master member having a nonundulant surface thereon corresponding to the desired surface of the memory member, applyiNg a coating comprising magnetic material to said master member surface, applying an intervening fluent bonding agent to said coating and to the surface of a substantially rigid substrate, whereby hardening of said bonding agent firmly secures said coating to said substrate, and releasing said coating from said master member after said bonding agent has substantially hardened.

25. A method as defined in claim 24;

wherein said bonding agent is a heat-hardenable synthetic resin.

26. A method as defined in claim 24;

wherein said bonding agent is an epoxy resin.

27. A method as defined in claim 24;

wherein said bonding agent comprises a nonmagnetic and electrically insulating material.

28. A method as defined in claim 24;

wherein said coating applied to said master member surface comprises a mixture of magnetic particles and a binder therefor, said bonding agent being applied directly to said mixture and said surface of said substrate.

29. A method as defined in claim 24;

wherein said coating applied to said master member surface comprises a mixture of magnetic particles and a binder therefor, said bonding agent being applied directly to said mixture and said surface of said substrate;

said bonding agent comprising a nonmagnetic and electrically insulating material.

30. A method as defined in claim 24;

wherein said coating applied to said master member surface comprises a magnetic plating, said bonding agent being applied directly to said plating and said surface of said substrate.

31. A method as defined in claim 24;

wherein said coating applied to said master member surface comprises a magnetic plating, said bonding agent being applied directly to said plating and said surface of said substrate;

said bonding agent comprising a nonmagnetic and electrically insulating material.