US3544732A - Magnetic transfer system with pneumatic means for maintaining tape contact - Google Patents

Description

United States' P'atent [72] Inventors Richard A. Bauer [56] References Cited Sin J UNITED STATES PATENTS [21] A 1 N 2;???- 2,918,537 12/1959 Camras 179/1002 3,l6l,l20 121964 T' t Iv 340 l74.l 221 Filed Jan. 15,1968 mares e [45] Patented Dec. 1, 1970 Primary Examiner-Bernard Komck [73] Assignee International Business Machines PP (ZN-pong Attorneys- Hanifin & .lancin and Vincent W. Cleary Armonk, New York a corporation of New York ABSTRACT: A magnetic transfer system that transfers a mag- MAGNETIC TRANSFER SYSTEM WITH net c lmage from a h1ghc0erc1v1ty master tape to a lower coer- TIC MEANS FOR MAINTAINING TAPE c1v1ty slave tape by passing them through a changing magnetic PNEUMA transfer field with the tapes having a pressure contact CONTACT I F therebetween while traveling through the field. The pressure is 2 5 Draw provided by fixed and movable heads that expel air toward the [521 (1.5. CI 179/ 100.2, two tapes. The transfer magnet is in the fixed head and the air 226/97 is expelled through two rows of holes on either side of the [51] Int. Cl. Gllb 5/86, magnetic air gap. A pneumatic system is employed to latch the 61 lb 15/38 movable head into a fixed position. A pressure chamber is [50] Field of Search 179/ 100.2(E), formed by the two heads with a check valve forming the enl00,2(P); 226/95, 108, 97;1340/l74.l(E), trance of the tape into the chamber and another check valve 174.10 forming the exit of the tape from the chamber.

SHEET 1 OF 2 32 31 L a i: O 310 v 31b PRESSURIZED" I 84 AIR SOURCE mvazvrozw RICHARD A. BAUER ELWOOD H. STORM AT T OR'NE Y i 44.732 PATENTEDBEU nm 3.5

SHEET 2 OF 2 MAGNETIC TRANSFER SYSTEM WITH PNEUMATIC MEANS FOR MAINTAINING TAPE CONTACT RELATED APPLICATION U.S. Pat. application Ser. No. 649,680 filed June 28, 1967 in the name of Racime J. van den Berg entitled Reproduction System and now U.S. Pat. No. 3,472,971.

BACKGROUND OF THE INVENTION 1. Field of the Invention Magnetic recording by magnetic transfer from a master tape to a slave tape.

2. Description of the Prior Art In conventional magnetic transfer devices, it is necessary to provide pressure between the master and the slave while the master and slave tapes are passing through the magnetic transfer field. Normally, this is done by pressure rollers or pressure pads forcing the tapes against the magnetic head. This results in more friction against the head than the roller so that a relatively large amount of slippage occurs between the tapes resulting in inferior reproduction.

In the above-identified patent application the pressure between the master and slave tape is achieved by applying air pressure to both sides of the tape.

SUMMARY OF THE INVENTION It is therefore an object of the invention to provide a new and improved magnetic transfer apparatus.

A further object of the invention is the provision of new and improved magnetic transfer apparatus that effects magnetic transfer of a magnetic image from a master to a slave tape with a high degree of accuracy and a minimum of noise.

A still further object of the invention is to provide a new and improved magnetic transfer apparatus which requires a minimum of power to accurately effect magnetic transfer of a signal from a master tape to a slave tape.

The above objects of the present invention are accomplished by a magnetic transfer device which employs drive means effecting movement of said tape in a predetermined direction.

Pressure means applies air pressure to opposite sides of said tape. In addition, a check valve located at one end of said air bearing tends to pass said air in only one direction. This check valve has four functions. It applies a threading force to the tapes past the pressure heads, substantially reduces noise for the air pressure outlets and greatly reduces air required for a desired pressure on the tape. In addition, it enables transfer of different thicknesses of tape which heretofore was not possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an isometric view of the magnetic transfer device embodying the invention;

FIG. 2 is a cross-sectional view taken along lines 2-2 of FIG.

FIG. 3 is a cross section taken along lines 3-3 of FIG. 2; FIG. 4 is an isometric view partially in cross section of the air pressure heads shown in FIGS. 13; and

FIG. 5 is an elevation view of the two pressure heads showing the limit or stop for the movable head shown in FIGS. 1- -4.

DESCRIPTION OF THE PREFERRED EMBODIMENT General Description The embodiment of the invention illustrated in the drawings comprises a support means having taped guiding means secured thereto. Mounted on the support means 20 are supply reels R1 and R2 and takeup reels R3 and R4. R2 holds a high coercivity master tape T1 containing a desired signal such as a video or audio signal to be transferred to a lower coercivity slave tape T2 on reel RI. The master tape T1 and the slave LII tape T2 are threaded between guides on support 20 and through a slot and into a chamber formed by two pressure heads 40 and 60 and are then attached by some suitable means to takeup reels R3 and R4, respectively. The fixed pressure head 40 contains a magnetic means which produces a varying magnetic field to transfer the signal from the master tape TI to the slave tape T2. The pressure head 60 has limited movement after release from a lock means 30 so as to aid in threading the tape through or between the heads 40 and 60. The movable head 60 does not contain means for producing a magnetic field, but does contain an air pressure source.

The air pressure in the head 40 is expelled through two rows of apertures on opposite sides of and parallel to the magnetic air gap in the head 40. The movable head 60 has air expelled through a row of holes opposite the magnetic gap in the fixed head 40. An air pressure source is employed to provide the required transfer pressure between tapes T1 and T2 effected by the pressure heads 40 and 60. The transfer field is created in a chamber formed by the heads and including one check valve 50 forming the entrance for the tape into the chamber and another valve 70 at the exit.

Detailed Description The support structure 20 includes a supporting plate 20a with rollers 21, 22, 23 and 24 mounted as shown in FIG. 1. These rollers are rotatably mounted on plate 200. In addition to these rollers for guiding the tape, there are two guide plates 25 and 26 (with slightly convex upper surfaces) having at one end tape guiding flanges 25a and 26a extending upwardly therefrom as shown in FIG. 1. At the other side ofthe pressure heads 40 and 60, are additional guide plates 27 and 28 which are positioned equidistant from reels R3 and R4. Likewise, roller 24 is positioned the same distance from roller 21 as roller 22 and plate 26 are from reel R2. The reels R3 and R4 could by employed in a cartridge as shown in dotted lines in FIG. 1. A torque motor M1 is provided to provide a drive for the reel R2. Likewise, a torque motor M2 is employed to drive reel RI... Suitable means are provided such as an opposing torque motor on supply reels R1 and R2 to maintain tape tcnsion while the tape is driven on to reels R3 and R4.

The movable head 60 is shown in FIGS. 3 and 4. This pressure head 60 comprises two blocks mainly rectangular block 61 and block 62. These blocks are secured together as shown in cross section in FIG. 3. Block 61 has a cylindrical air pressure chamber 63 which is closed at one end and has an opening 63a at the other end. The pressure chamber 63 extends nearly the full length of block 61. Block 62 has a rectangular recess 65 which is closed at both ends and extends nearly the full length of the head 60. Cylindrical bores 64 in block 61 provide communications between chamber 63 and chamber 65. A row of apertures 66 provides communications between chamber 65 and the atmosphere. Rectangular blocks 67 are secured to blocks 61 and 62 at either end of block 62 and extends upwardly from the row of holes 66 so as to effect the spacing between head 60 and head 40 extending between blocks 67. Thus, section 62, blocks 67 and head 40 define an air pressure chamber through which the tapes T1 and T2 pass.

The fixed head 40 comprises two sections; rectangular block 41 and block 42, which are secured together as shown in FIGS. 3 and 4. Section 41 has a cylindrical air pressure chamber 43 which is closed at one end with an opening 43a at the other end. Section 42 has a conventional erase type magnet 47 having windings 48 and a longitudinally disposed magnetic gap 49 as shown in FIGS. 3 and 4. As shown in FIG. 3 the magnet 47 is positioned in a longitudinally disposed recess in section 42 so that the magnet 47 forms with this recess rectangular air pressure chambers 45 and 46. The chamber 46, closed at both ends, communicates with the outside of the head by way of a row of linearly disposed row of apertures 46a. The chamber 45, also ,closed at both ends, communicates with the outside of head 40 by way of a row of linearly disposed apertures 45a. The row of apertures 45a and the row by wayof a plurality of cylindricalpassages 44a. Chamber 43 also communicates with chamber. 46 by way of a plurality of parallel cylindrical passages 44b.

Hence,it is seen that air pressure applied from pressurized air source 80 through conduit 82, aperture 434, chamber 43,

results in air being expelled through the rows of apertures 45a and 46a sincethe air in chamber 43 will pass through passages 44a; chamber 45, and apertures 45a.i.Similarly, such air will pass through apertures 44b, chamber 46 and, apertures 46a.

Conduit 81 is secured to aperture 630 to provide air pressure inchamber 63 which then passes through the plurality of cylindrical passages 64 into chamber65 expelling air through therow of apertures 66. Therow of apertures 66 is directly opposite the magnetic gap 49.

The windings 48 are connected to an'excitation source (not shown)'so as to providea proper magnetic transfer field at the a gap 49. The pressure required to effect magnetic transfer in the presencefof this field is provided on oneside of the tapeby thetworows formed by apertures 45a and 46a on one side and the row of apertures 66 formed on the other side.

: As stated above an air pressure chamber is formed by the two rectangular blocks 67 which contact the ends of the block 42 so as to provide a spacing between block 42 and block 62.

Thus these elements define this air pressure chamber.

At the entrance of this chamber is a check valve 50 tending to prevent air from: traveling through the entrance of the. chamber .to the outside.-Thisv valve is formed by a flexible membrane'52 having a semicylindrical curved end portion 52a; The membrane 52 is secured to block 62 by alongitudinallydisposed member51. The'curved portion 52a is nor mally in light contact with tape-T2. At the other side of the valve is a flexible membrane 56 which is secured to block 42 by longitudinally disposed member54. The membrane 56 has 1 .a longitudinally disposed semicylindrical curved endportion 56a which normally remains in light contact with tape T1.

Elements 51, 52, 52a, 54, 56, and 56a span the distance between terminal blocks67. Hence, member 52a and 56a provide an input check valve to the above air chamber.

With theabovecheck. valve 50 less air pressure is required for the source 80 to effect magnetic transfer. In addition, air pressure so lusedvresults in'driving the tape through the air pressure chamber. Furthermore, less noise results from the air pressure. I A removable exit valve 70 as shown in the drawing can be utilized to further reduce the required air pressure for magnetic transfer. Valve 70 is positioned at the exit of the tape from the transfer chamber. This valve is formed on one sideby a flexible membrane 73 having a semicylindrical end 73a. The element 73'issecured to block 62 by rectangular block 71. Portion 73a is normally in light'contact with tape T2.

i The other portion of the valve 70v is formed bya flexible membrane 76 having a semicylindrical end 76a which element 76 is secured to block 42 by rectangularblock 74.

Elements 71, 73, 73a, 74, 76 and 76a span the distance 1 between the two rectangular blocks 67.

Mounted on either end of the stationary pressure head is either end. As shown in FIG. 5 the purpose of these stop memhers is to provide anialineme'nt means for movable head 60 and to limititsbackward movement to a distance 'dso as to provide proper alinement despite movement of the movable .head 60. Also, theyinsure proper tape tracking in fast rewind motion.

The transfer excitation source connected to windings 48 As shown in FIGS. 1 and 2, an L-shaped member 35 is pivotally connected at one end 37 to the movable pressure The air pressure source 80 has a'conduit 83 connected to a two-way solenoid valve 84 which connects conduit 83 to either side of the piston of cylinder131. Energizing solenoid valve 84 feeds air to conduit 31a and causes the piston 31c, arm 32, 33 and roller 34 to move to the right. This results in locking the movable head 60 against the fixed head 40. It will be noted that end blocks 67 provide aclearance or a slot in the closed position through which the master and slave tape can be threaded and the recording can be transferred. Viewing FIG. 2, if the solenoid valve 84 is deenergized, the air pressure is provided to the conduit 31b, the piston 31c moves to the left with piston arm 32 moving an arm33 to the left so that a roller 34 and arm 33 are moved to the left on slanted surface 35a on L-arm 35. In so doing, spring 21a rotates L-arm 35 counterclockwise until head 60 hits stops 51L and 51R. The arm 33 extends through slot 21 of the base 20a. In this position, the movable head 60 and head 40 provide a relatively large slot for threading the master and slave tape.

Operation of the Invention With the head 60 in the retracted position, the master tape T1 from supply reel R2 is, as shown in FIG. 1, threaded above the roller 22, over guide 26 and through valve to the chamber formed by heads and 40 and then through valve 70. It is then fed beyond and below the guide member 28. It is then fed below roller 24 and upwardly onto the takeup reel R4. Tape T1 is then secured to reelR4 by some suitable means (not shown).

The slave tape T2 is fed off the supply reel R1 upwardly over roller 21, over flat guide 25, past 'valve 50, through the chamber formed by the heads 40 and 60 and through valve 70. It is then fed downwardly below the guide 27. it is then fed under roller 23 and upwardly to be secured in some appropriate fashion on the takeup reel R3. Flanges 25a and 25b act as tape edge guides.

During magnetic transfer, the takeup reels R3 and R4 are driven by motors M1 and M2.

. a. pair of L-shaped stop members shown in FIGS. 1, 2, 3, and 5. These stop members are numbered 51L and 51R with a'pair at provides an alternating current.(of about 100 kc.). A source a and head could also be used such as illustrated in US. Pat. ap-' After the tape has been threaded in this appropriate fashion, the solenoid valve 84 is energized feeding air through the conduit 31a so as to drive the roller 34 to the right (FIG. 2) on the canted surface 35aand thereby move the pressure head 60 toward pressure head 40 so that the end blocks 67 are in con-' tact with the ends of block 42. Due to end blocks 67, a spacing 'is provided so that the master tape T1 and the slave tape T2 will not contact either of the pressurepads 40 or 60 when air pressure is applied (as illustrated in FIG. 3).

During magnetic transfer (with reels R3 and R4 being driven), an excitation source (not shown) provides current to effect the appropriate varying magnetic transfer field by way of the winding 48 wound about the magnet 47. Due to this magnetic field as is well known in the art, the magnetic image on the master tape TI is transferred to the slave tape T2 as the tapes are driven past the transfer station definedby the two pressure heads and the magnetic gap 49.

As the tapes are so driven past the transfer station, air pressure is provided through conduit 81 into pressure chamber 63. through passage 64 and thence through the row of holes 66. This provides a uniform air pressure against slave tape T2 directly opposite to the magnetic gap 49.

While the pressure is being applied as above through the pressure head 60, air pressure is provided through conduit 82 into chambers 45 and 46 and holes.45a and 46a. Thus, air,

pressure from the magnetic gap 49 is applied to the master tape Tl directly opposite to the air pressure provided by the holes 66 to the slave tape T2.

It can be seen that air pressure will tend to close valve 50. Valve 70, on the other hand, needs some preloading to keep closed or nearly closed with substantial air pressure being supplied to the chamber. The flexible membranes of these valves (52, 55, 73, 76) can be constructed of Teflon" or Mylar.

Thus, it is seen that as the tape is driven through the excitation field supplied by magnet 47, air pressure is applied through the row of holes 45a and 46a on one side and the row of holes 66 on the other side of the tapes. This air pressure provides the necessary pressure between the tapes required for magnetic transfer. It has been found that the tape will be shaped as shown in FIG. 3 utilizing these holes. Due to the valve 50 as well as valve 70, the required pressure necessary through these holes is substantially reduced as well as the noise created by such pressure. In addition, the air pressure creates a suction that threads the tape through the chamber. lf valve 70 is removed, or not used, the suction is substantially greater.

In addition to the above features it was discovered that without the above input valves magnetic transfer of tapes of varying thicknesses (e.g., spliced tape) was not possible. When the distance between the heads was increased to accommodate the splice the air pressure "spilled out" and sufficient pressure could not be attained without the use of an extremely large air source. By the use of only valve 50, however, the heads could be spaced to accommodate splice tape and transfer achieved with a relatively small air pressure source.

It will now be obvious to those skilled in the art many modifications and variations accomplishing any or all of the objects of the invention and realizing many or all of its advantages but which, however, do not essentially depart from the spirit of the invention.

We claim:

1. A magnetic transfer device for transferring a magnetic pattern from a master magnetic medium to a magnetizable copy medium comprising:

a pressure chamber;

excitation means for producing a magnetic transfer field,

within said pressure chamber;

means effecting movement of said master and said slave medium from one side of said chamber to another side of said chamber; and

means placing said master medium in contact with said copy medium within said magnetic transfer field, including:

A first pressure means applying fluid pressure to said master medium on one side, within said magnetic field;

second pressure means applying fluid pressure to said copy medium on the opposite side within said magnetic field;

valve means located at said one side of said chamber and providing an entry for said master and said copy medium into said pressure chamber; and

said valve means including flexible membrane means operable upon the application of said fluid pressure for closing said entry.

2. A magnetic transfer device for transferring a magnetic pattern from a master magnetic medium to a magnetizable copy medium comprising:

a pressure chamber;

excitation means for producing a magnetic transfer field,

within said pressure chamber;

means effecting movement of said master and said slave medium from one side of said chamber to another side of said chamber; and

means placing said master medium in contact with said copy medium within said magnetic transfer field, including:

a first pressure means applying fluid pressure to said master medium on one side, within said magnetic field;

second pressure means applying fluid pressure to said copy medium on the opposite side within said magnetic fieldvalve means tending to prevent movement of fluid outwardly from said pressure chamber;

a second valve means located at said other side of said chamber for providing an exit for said tape from said chamber and for restraining movement of air from said chamber; and

said second valve means including flexible membrane means operable on the application of said fluid pressure to close said exit.

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