Stationary magnetic head with a fluid operated tape lifter

• US 4,479,158 A
• Filed: 05/12/1982
• Issued: 10/23/1984
• Est. Priority Date: 05/12/1982
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Hu, Paul Y., Froehlich, Frederick B.
• Primary Examiner(s): Wolff, John H.
• Application Number:
  US06/377,284
• Time in Patent Office: 895 Days
• Field of Search: 360/102-103, 360/109, 360/121-122, 360/125, 360/130.1
• US Class Current: 360/130.1
• CPC Class Codes: G11B 15/62 Maintaining desired spacing between record carrier and head
• CPC Class Codes: G11B 5/187 Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features G11B5/265, G11B5/29 , G11B5/31 take precedence
• CPC Class Codes: G11B 5/4893 relative to moving tape

Abstract

Fluid is introduced under pressure to the operative face of a magnetic head to lift the magnetic media out of contact with the transducers when the media is stationary or about to be stopped. The media is lifted only locally with respect to the multiple transducers of the magnetic head. The fluid pressure tents the tape with the pressure adjusted such that the media forms a seal with the head at the edges of the media to hold the fluid within the tent-like structure. Slots formed in the magnetic head at the leading and trailing edges allow the fluid to escape to keep the media from excessively lifting from the magnetic head. The fluid pressure is under control of a valve that introduces the pressure to the operative face of the head as well as opening the operative face to atmospheric pressure when the fluid pressure is halted to permit the media tension to quickly pull the media back into contact with the transducers by assisting the slots in dissipating the fluid pressure.

Claims

1. A magnetic head for sensing magnetic transitions from a flexible magnetic medium comprising:

a plurality of transducers situated on an operative face of the head for sensing the magnetic transitions as the medium passes adjacent to the transducers;

said operative face having a plurality of slots, at least some of which are formed parallel to the motion of the medium and adjacent to the leading and trailing edges of the medium contact with the operative face;

means for introducing fluid under pressure between the medium and the operative face of the head; and

means connected to said fluid introducing means for controlling the fluid under pressure entering into said fluid introducing means;

said fluid introducing means, when actuated, introducing the fluid under pressure such that the medium forms into a tent-like structure over the operative face of the head with the fluid being contained within the tent-like structure and permitted to controllably escape through the slots;

said controlling means being actuated to provide fluid to said fluid introducing means when said medium is substantially stationary relative to said head;

wherein said fluid will quickly evacuate through the slots when said controlling means stops the entry of fluid under pressure into said fluid introducing means.

2. A magnetic head as defined in claim 1 wherein said controlling means opens said fluid introducing means to atmospheric pressure in the deactivated state.

3. A magnetic head as defined in claim 1 wherein said fluid under pressure effects a wedge lift of the media in a hinge format at the parallel slots and adjacent to the leading and trailing edges of the operative face.

4. A magnetic head as defined in claim 1 wherein said fluid introducing means opens through the operative face of said head.

5. A magnetic head as defined in claim 1 wherein said fluid introducing means is a tube extending through the operative face at the approximate center of the operative face.

6. A magnetic head as defined in claim 2 wherein said controlling means includes a normally open valve which opens said fluid introducing means to atmospheric pressure when inactive and a normally closed valve that prevents the fluid under pressure from entering into said fluid introducing means.

18. The recording device of claim 1, 2, 3, 6, 7, 8, 11, 12, 15 or 16 wherein said medium is tape.

21. A magnetic head as defined in claim 1, 2, 3, 6, 7, 8, 12, 16, 19 or 20 wherein said slots are evenly separated across the width of said medium at each edge parallel to said medium motion to thereby enable said fluid under pressure to support said medium in an even and low profile over said head.

22. A magnetic head as defined in claim 1, 2, 3, 6, 7, 8, 11, 12, 15, 16, 19 or 20 wherein said fluid under pressure is maintained at a pressure between 2 and 5 pounds per square inch.

23. A magnetic head as defined in claim 1, 2, 3, 6, 7, 8, 12, 16, 19 or 20 wherein said slots are situated on said head so as to establish a symmetrical lifting pattern of said medium over said head when provided with said fluid under pressure.

7. In a magnetic head for sensing magnetic transitions from a flexible magnetic medium, said head including a plurality of transducers on an operative face of said head for sensing the magnetic transitions as the medium passes adjacent to the transducers, and said operative face having a plurality of slots formed thereon, at least some of said slots being parallel to the motion of the medium and adjacent to either a leading or a trailing edge of said operative face, wherein the improvements comprise:

means for introducing fluid under pressure between the medium and the operative face of the head;

means for controlling the fluid under pressure entering into said fluid introducing means;

said controlling means, when deactuated, opening the fluid introducing means to atmospheric pressure and, when actuated, closing said fluid introducing means to atmospheric pressure and entering the fluid under pressure into said fluid introducing means to form the medium into a tent-like structure over the operative face such that the introduced fluid is contained within the tent-like structure while permitted to controllably escape through the slots and wherein said fluid will escape through the slots when said controlling means is inactivated to stop the entry of fluid under pressure into said fluid introducing means; and

means for actuating said controlling means when said medium is stationary or near stationary with respect to said head.

9. A magnetic head as defined in claim 7 or 8 wherein said fluid under pressure effects a wedge lift of said medium at a first point of entry of said fluid into said slots, said slots thereby permitting a controlled flow of fluid through said slots and thereby enabling said medium around the periphery of said head to be in a substantially hinged contact with said head.

10. A magnetic head as defined in claim 7 or 8 wherein said controlling means includes a normally open valve which opens said fluid introducing means to atmospheric pressure when inactive and a normally closed valve that prevents the fluid under pressure from entering into said fluid introducing means except when said medium is stationary or near stationary relative to said head.

8. A stationary magnetic head including;

a plurality of transducers situated on an operative face of said head in transducing relationship with a flexible magnetic medium;

said operative face having a plurality of slots formed thereon, said slots extending parallel to the direction of relative motion between said medium and said head and being situated adjacent to the leading and trailing edges of medium contact with the operative face;

means for introducing fluid under pressure between the medium and said operative face;

means connected to said fluid introducing means for controlling the provision of fluid under pressure to said fluid introducing means;

said fluid introducing means introducing fluid under pressure between said medium and said operative face so that a portion of said medium over said operative face is displaced from said face and forms a tent-like structure with said fluid being retained within said structure and permitting the introduced fluid to controllably escape through the slots;

said controlling means being actuated to provide fluid to said fluid introducing means when said medium is stationary or near stationary relative to said head; and

wherein said fluid will quickly evacuate through said slots when said means for controlling the provision of fluid is deactivated to stop the entry of fluid under pressure into said fluid introducing means.

11. In a magnetic recording device having a magnetic head which is generally stationary during operation, said head having a transducing surface, and a flexible recording medium moving across said transducing surface during magnetic transducing operations;

a fluid entry device having fluid communication to said transducing surface for introducing fluid between the transducing surface and the recording medium to create a fluid bubble therebetween; and

valve means connected to said fluid entry device for selectively releasing fluid under pressure through the fluid entry device to selectively create said fluid bubble in a center region of the transducing surface thereby preventing contact between the flexible recording medium and the transducing surface when the recording medium movement speed is less than a certain predetermined value whereby said recording medium is prevented from clinging to said magnetic head.

12. The recording device of claim 11 wherein said transducing surface has a plurality of slots extending in a direction paralleling the direction of said movement between the recording medium and the transducing surface whereby the escape of fluid from the center region of the transducing surface is greatest in the direction of movement of the recording medium.

13. The recording device of claim 12 wherein said fluid entry device is a tube.

14. The recording device of claim 12 wherein said fluid entry device is a tube opening into said center region.

15. The recording device of claim 11 wherein said fluid entry device opens to atmospheric pressure when said recording medium movement exceeds said predetermined value.

16. The recording device of claim 12 wherein said slots include a first plurality of parallel slots extending from a first edge of said head and a second plurality of parallel slots extending from a second edge of said head, said first and second edges being transverse to the movement of said medium.

17. The recording device of claim 12, 13, 14 or 16 wherein said fluid pressure is sufficient to raise said medium off said surface at said center portion of said surface and said slots controllably release a sufficient amount of the introduced fluid so as to maintain said medium situated around a periphery of said surface in substantial contact with said surface to form said fluid bubble.

19. A generally stationary transducing head adapted to exchange signals with a flexible record medium disposed in a transducing relationship with said head when said head and said medium are in relative motion, comprising:

an operative face on said head facing outwardly toward said record medium, said operative face extending to a leading and trailing edge of said head;

said operative face having a plurality of slots extending from said leading and trailing edges towards a central portion of said face, said slots extending in the direction of said relative motion between said head and said medium;

means at said operative face for introducing fluid under pressure between said operative face and said medium for moving said medium away from said operative face a distance determined by the fluid introduced between said face and said medium and as permitted to controllably escape through said slots, said fluid under pressure and said slots combining to maintain a central portion of said medium out of contact with said operative face and a peripheral portion of said medium surrounding said central portion in contact with a peripheral portion of said operative face to thereby form said medium into a tent-like shape over the operative face of said head; and

means connected to said introducing means for supplying said fluid under pressure to said introducing means when said relative motion is below a predetermined speed.

20. A generally stationary transducing head adapted to exchange signals with a flexible record medium disposed in a transducing relation with the head, the head having at least one transducer with at least one gap arranged to scan at least one track on the flexible record medium as the head and flexible record medium relatively move at a predetermined speed in the transducing relation;

the improvement including, in combination;

the head having an operative face with the transducer facing outwardly toward the record medium, the operative face having a leading and trailing edge and a plurality of slots extending along the direction of said relative motion in juxtaposition to said leading and trailing edges, respectively;

means having fluid outlet ports at said operative face for controllably introducing fluid under pressure at said operative face adjacent said transducer and between said flexible record medium and said operative face for moving said flexible record medium from said transducing relation a distance determined by said introduced fluid controllably escaping through said slots from between said operative face and said flexible record medium such that said flexible record medium forms an outwardly extending tent-like shape immediately over said transducer; and

means connected to said introducing means for supplying said fluid under pressure to said introducing means when said relative motion between said operative face and said flexible recording medium is below said predetermined speed.

24. In a magnetic tape recorder having tape transport means for transporting tape along a transport path, a magnetic head disposed along the transport path and having a transducing surface facing said transport path so that a magnetic tape being transported along said path in a tape motion direction is in a transducing relation to said magnetic head transducing surface, a plurality of magnetic transducers in said head each having a transducing portion facing said transport path at said transducing surface and being in a predetermined spaced-apart array centrally of said transducing surface;

stop means in said tape transport means to stop the tape in said tape transport path so that a magnetic tape rests on said magnetic head transducing surface and start means in said tape transport means to start the magnetic tape to again move along said tape transport path in said transducing relation;

said magnetic head having first and second edges extending transversely to said tape transport path tape motion direction and being spaced apart along said tape transport path;

said magnetic head having first and second sets of elongated slots opening to said tape transport path and extending, respectively, from said first and second edges toward said spaced-apart centrally-located magnetic transducers;

a bubble generator in fluid communication with said transducing surface for supplying fluid under pressure intermediate said transducing surface and said magnetic tape and in juxtaposition to said magnetic transducers; and

a bubble controller coupled to said bubble generator and to said tape transport means for responding to said tape transport means stop means stopping said magnetic tape to actuate said bubble generator to supply fluid under pressure adjacent said magnetic transducers such that a fluid bubble of predetermined extent is created intermediate said magnetic transducers and said magnetic tape, said bubble extending for less than the entire extent of said magnetic tape facing said magnetic head with a predetermined portion of said supplied fluid escaping from being intermediate said transducing surface and said magnetic tape for limiting the generated bubble to be less than said extent of the magnetic tape facing the magnetic head and having further means responsive to said tape transport means start means to stop supplying said fluid such that the start of the magnetic tape movement and removal of the bubble are synchronized whereby the magnetic tape being started returns toward its transducing relation with the magnetic head while the magnetic tape is starting to move.

25. A method for controlling an interface condition between a flexible medium and a generally stationary magnetic transducing head when a portion of said medium is in a stationary or near stationary condition adjacent an operative face of said head, comprising the steps of:

supplying fluid under pressure to an interface area between said medium and said operative face, when said medium is in said stationary or near stationary condition; and

permitting the controlled escape of said fluid under pressure from said interface area so that said medium is held away from said head in a central portion of said head but remains in contact or near contact with a peripheral portion of said head.

26. A method for controlling an interface region between a generally stationary transducing head and a flexible record medium disposed in a transducing relation with said head comprising the steps of:

introducing fluid under pressure into said interface region between said head and said medium when said medium is stationary or nearly stationary with respect to said head;

controlling the flow of fluid under pressure so that said interface region is open to a source of fluid under pressure when said medium is stationary or near stationary and is open to atmospheric pressure when said medium is in motion relative to said head; and

controlling the escape of fluid under pressure from said interface region by means of slots formed in distal portions of an operative face of said head for enabling portions of said medium around the periphery of said operative face to be in contact or near contact with said face and portions of said medium near a central portion of said face to be kept out of contact with said face.