US3674943A

US3674943A - Handheld magnetic transducer with tip members having a hemispherical reading portion

Info

Publication number: US3674943A
Application number: US855122A
Authority: US
Inventors: William G Benson
Original assignee: Litton Business Systems Inc
Current assignee: Western Atlas Inc; Sweda International Inc
Priority date: 1969-09-04
Filing date: 1969-09-04
Publication date: 1972-07-04
Anticipated expiration: 1989-07-04
Also published as: CA922018A

Abstract

A handheld magnetic transducer comprises a gun-shaped housing having a directional arrow on one surface. The arrow is illuminated by a light within the housing indicating the operating state of the transducer as determined by a signal device. The housing has dimples in opposed side walls for ease of grasping. The armature is in two parts. Each part has a T-shaped portion the crossbars of which overlap. The armature is inserted within the bobbin and is resiliently held at the crossbars to lock into position with a shim. The bobbin front wall in combination with the armature and shim form the muzzle or reading end of the transducer and has a substantially frustro pyramidal shape. The armature-bobbin structure is held in place by fingers which form a part of the transducer housing. The wires from the coil are secured to clips. The clips or terminal are U-shaped members spring retained on arms of the bobbin. The clips each have a flange portion for engaging an aperture in the arm. The reading portion of the transducer is hemispherical in shape with the gap defining an arc thereon such that the transducer is capable of rotation or positioning about one of three axes while moving relative to a record.

Description

United States Patent Benson [4 1 July 4,1972

[54] HANDHELD MAGNETIC TRANSDUCER WITH TIP MEMBERS HAVING A' HEMISPHERICAL READING PORTION [72] Inventor: William G. Benson, West Orange, NJ.

[73] Assignee: Litton Business Systems, Inc., New York,

[22] Filed; Sept. 4, 1969 [21] Appl. No.: 855,122

[52] U.S. Cl. ..l79/100.2 C

[51] Int. Cl. ..G1lb 5/22 [58] Field of Search 1 79/1002 C, 100.2 CA; 35/35 C [56] References Cited UNITED STATES PATENTS 2,548,011 4/1951 Frost ..35/35 C 2,822,425 2/1958 Hicks ....35/35 C 3,416,241 12/1968 Weitzner ..35/35 C Primary Examiner-Bernard Konick Assistant Examiner-Robert S. Tupper Attorney-Norman Friedman, Philip Furgang, Morris 1. Pollack, Arthur T. Groeninger and Stephen E. Feldman [5 7] ABSTRACT A handheld magnetic transducer comprises a gun-shaped housing having a directional arrow on one surface. The arrow is illuminated by a light within the housing indicating the operating state of the transducer as determined by a signal device. The housing has dimples in opposed side walls for ease of grasping. The armature is in two parts. Each part has a T- shaped portion the crossbars of which overlap. The armature is inserted within the bobbin and is resiliently held at the crossbars to lock into position with a shim. The bobbin front wall in combination with the armature and shim form the muzzle or reading end of the transducer and has a substantially frustro pyramidal shape. The armature-bobbin structure is held in place by fingers which form a part of the transducer housing. The wires from the coil are secured to clips. The clips or terminal are U-shaped members spring retained on arms of the bobbin. The clips each have a flange portion for engaging an aperture in the arm. The reading portion of the transducer is hemispherical in shape with the gap defining an arc thereon such that the transducer is capable of rotation or positioning about one of three axes while moving relative to a record.

2 Claims, 14 Drawing Figures PATENTEDJUL'"4|912 SHEET 10F 3 FIG.

INVENTOR WILLIAM G. BE NSON PATENTEIJJUH I972 3.674.943 sum 2 or a 79 A m w %,7/,

WILLIAM BENSON ATT N PKTENTEDJUL4 I972 3. 674. 943

sum aor a F' l (3. 9o. 204 I PRIOR ART INVENTOR WILLIAM G. BENSON HANDHELD MAGNETIC TRANSDUCER WITH TIP MEMBERS HAVING A HEMISPHERICAL READING PORTION BACKGROUND OF THE INVENTION This invention relates to transducers and more particularly to components thereof. I

In the recording onto or reading from a magnetic record, such as a magnetic tape, card, or the like with electromagnetic transducers of the prior art, it is necessary to maintain correct spacing and positioning of the transducer with respect the record. As is well known in the art, electromagnetic transducers are generally constructed of one or more pole pieces made of iron, ferrite, or the like and fashioned into a generally ring-shaped body. The pole pieces are either cut or formed such that two abutting faces thereof are parallel and closely spaced but do not touch. This resulting space, termed the gap, is required for both the reading and recording functions. The gap may be filled with air or some other material having a lower permeability than the surrounding pole pieces. As a result, flux passing from the pole pieces to the gap material is caused to fringe and strike the magnetic record placed closely adjacent the transducer. In this manner recording is permitted to take place. In a similar manner, the gap is used to sense the flux surrounding a magnetic area of a magnetic record and permit its introduction into the pole pieces which conduct the flux to a pickup coil for conversion to a read current.

The amount of read current available will be dependent upon the original strength of the magnetized area of the magnetic record, the materials of the pole pieces and gap, and the shape, position, and spacing of the gap with respect to the record media. Increasing the spacing between the gap and the magnetized area will reduce the flux reaching the transducer thus reducing the read current. Further, any angular change in the position of the gap with respect to the record media from the required perpendicular position will effectively increase the gap to media spacing and decrease the received flux. Skewing of the position of the gap from its normal position, perpendicular to the lines of flux, may introduce spurious signals from adjacent recorded areas, and decrease the available flux.

In order to minimize positioning errors of the type described above and increase the effective flux employed to produce the reading current, the path of movement of the record is carefully controlled and the transducer is rigidly mounted to maintain desired spacing and alignment with the magnetic record media. Such rigid mounting is also necessary for the trans ducer during recording because alignment errors reduce the flux reaching the media and thus reduce the recording strength and enlarge the recording area. With this requirement for rigid mounting it is not possible to record and read magnetic records with a transducer which is manually positioned by an operator with respect to a record.

Numerous types of handheld transducers have been suggested. Generally, these transducers are pen-shaped. One such example is disclosed by Frost in U.S. Pat. No. 2,548,011. Penshaped transducers have a major disadvantage in that the user may tire of holding same and that the pen-shape may slip. In addition orientation may prove exceedingly difiicult, especially where the transducer lacks means for orientation with respect to a record.

It is well known to use two sections of an armature in fonning a completed transducer. Such devices have been disclosed by Joanou in U.S. Pat. No. 3,105,965 and Ferber in U.S. Pat. No. 2,785,838. In such arrangements, however, the armatures must be held together by complex gripping members such as clamping blocks or the like. Such combinations make for expensive and complex assemblies.

SUMMARY OF THE INVENTION A handheld transducer housing comprises three walls. The first wall has a surface disposed in a first imaginary plane and is adapted to accommodate a first finger of the hand of the user. The second wall has a surface disposed in a second imaginary plane spaced from the first imaginary plane and is adapted to accommodate the second finger which is adjacent a second finger of the user. The third wall has a surface intersecting the first and second surfaces and adapted to accommodate a third finger, adjacent the second finger, of the user.

A handheld transducer housing comprises means for transducing the information from a record. The transducing means is substantially responsive upon being moved proximate to the record in at least one predetermined direction. The housing has indicating means disposed in the housing for indicating the predetermined direction.

A handheld transducer housing comprises transducing means within the housing for transducing a signal, the housing having at least two walls each having surfaces lying in an imaginary plane and each of the walls having therein depressions for accommodating the fingers of the hand of the user.

An electromagnetic transducer of the type having an armature. The armature has a coil about it. The transducer is adapted for use with a magnetic record, the record having lines of flux arranged in an intended reading path. The transducer comprises at least one reading head affixed to the armature, the reading head having a substantially hemispherical reading portion.

An armature for an electromagnetic transducer comprises two members. These members have generally enlarged portions. The enlarged portions are placed in proximity such that the members in combination comprise the armature.

A bobbin for an electromagnetic transducer. The bobbin has a core mounted assembly for holding wire thereon. In addition it has means for supporting an armature and includes means for engaging a shim.

An electrical terminal or clip for use with a bobbin of an electromagntic transducer. The clip is substantially U-shaped having three walls. The first and third walls being inclined to have one another to be spring loaded into assembly with the bobbin.

A handheld transducer comprises a housing and means for illumination within the housing for indicating an operating condition of the transducer. A housing comprises means for transducing the information from a record. A transducing means within the housing is substantially responsive upon being moved proximate the record in at least one predetermined direction. The housing has indicating means disposed in said housing for indicating the predetermined direction and the illuminating means for indicating the operating state of the transducer.

A handheld magnetic transducer comprises a gun-shaped housing, a bobbin within the housing, an armature within the bobbin and extending through a laterally extending wall of the bobbin. The armature and the wall forming the muzzle end of the housing. An electrical cable for transmitting information from that transducer is disposed within the housing and extends from the handle end thereof.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a transducer constructed in accordance with the invention;

FIG. 2 is an exploded perspective view of a bobbin, shim, armature, and electrical connectors constructed in accordance with the invention;

FIG. 3 is a sectional view of the transducer of FIG. 1.

FIG. 4 is a partial sectional view of the transducer of FIG. 3 taken through lines 4-4;

FIG. 5 is an elevational view looking into the transducer of FIG. 3 with one wall of the housing removed;

FIG. 6 is an elevational view of the bottom or transducing end of the transducer of FIG. 3;

FIG. 7 is a perspective view of the transducer of FIG. 1 in use;

FIG. 8 is a perspective view of a ducer;

prior art magnetic trans- FIGS. 9a and 9b are schematic views of a prior art transducer; and

FIGS. 10a, b, and c, are perspective views of the transducer of this invention disclosing several types of movement thereof.

FIG. 11 is a section taken on line 11-11 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Disclosed herein is an electromagnetic transducer to be used in conjunction with magnetizable record bearing media. This transducer is so designed as to be manually positionable with respect to a record. Thus, the transducer may be moved without special apparatus for guidance or control with respect to the record bearing media.

The magnetic transducer 10 (as shown in FIG. 1) has therein a bobbin 12 (FIG. 2) which may be constructed of plastic, hard rubber, or other insulating materials.

The bobbin 12, as commonly used in the art, retains in place a coil of wire 14 (shown in phantom in FIG. 2 and in section in FIGS. 3 and 4). The coil 14 serves as a means for having induced therein an electric current by flux in an armature. It will be understood that the coil 14 may have any shape configuration as is known in the art.

The bobbin 12 is substantially spool-shaped in its construction having two flat,

opposed end walls

16 and 18. Disposed between the

end walls

16 and 18 and holding them rigidly apart is a rectangularly shaped core member 20. The coil 14 is wrapped about the core 20 in a manner commonly known in the art. Extending through the

end walls

16 and 18 and the core 20, is a bobbin aperture 22. The front end wall 18 has a surface perpendicular to the core 20 which is substantially frustro pyramidal in shape 24.

A shim aperture 26 (see FIGS. 3 and 4) extends perpendicularly from the bobbin aperture 22 into the frustro pyramidal front end 24 of the front end wall 18 of the bobbin l2.

The rear end wall 16 of the bobbin 12 has extending upwardly therefrom and substantially parallel with the axis of the bobbin aperture 22 two arms, 28 and 30. These

arms

28 and 30 form a contiguous part of the bobbin 12. The first arm 28 has therein two apertures, 32 and 34, adapted to receive screws. The second arm 30 has a similar aperture 36. In addition, adjacent each of these

apertures

32, 34, and 36 are flange retaining insets. Only one 38 is visible in FIG. 2.

On the first arm 28 separating apertures 32 and 34 is a laterally extending ridge 40 made of insulating material. In the preferred embodiment this ridge 40 is molded as part of the arm 28. The ridge 40 may be equidistant between the apertures 32 and 34. The function of the ridge 40 is more fully described below.

The handheld magnetic transducer 10 employs the use of a novel set of clips 42. The clips 42 are of substantially U shaped construction, having rectangularly shaped

side walls

44, 46, and 48. The first side wall, 44 has an aperture 50 therein, the function of which is more fully described below. The second side wall 44 forms the base side of the U configuration of the clip 42. The third side wall 48 has a tab 52 which extends laterally from the third side wall 48 and parallel the bottom wall 44 of the clip 42. The tab 52 has a substantially T- shaped head portion 54. This tab 52 may be cut or punched out of the third side wall 48 leaving therein a T-shaped aperture 56.

At the free end of the third side wall 48 is an L-shaped flange 58. This flange 58 extends parallel to the second side wall 46 and inwardly of the U-shaped clip 42. The U-shaped clip 42 may be constructed of a conducting material, such as copper, or spring steel. The

side walls

44 and 48 of the U- shaped clip 42 incline inwardly toward one another. In place on the

arms

28 and 30, the L-shaped flange 58 resides in the flange retaining insert 38. The

apertures

32, 34, and 36, respectively, are each in alignment with the apertures 50 and 56 of each of the clips 44. The

side walls

44 and 48 act as springs to hold the clips 42 securely to the

arms

28 and 30.

The tab 52 is designed for the attachment, by solder or otherwise, of wire 60 (FIG. 5) from the coil 14. The head 54 of the tab 52 serves to prevent the wires 60 soldered thereto from slipping off. The bobbin 12, has in its rearward wall 16 a notch 62 through which are placed the wires 60 of the coil 14. The ridge 40 serves to insulate and separate the clips 42 on the first arm 28 from coming into contact with one another.

The handheld magnetic transducer 10 employs a shim 64. The shim 64 of this invention has an upwardly extending boss 66. As is commonly known in the art, the shim 64 is made of a nonmagnetic material and may be approximately five-onethousandth of an inch in thickness. The boss 66 may be made by means ofpunching into a die or molding.

The general function of a shim is to keep the reading head of an armature in place. The broader functions of the shim of this invention will be more fully described below.

As may be seen from the drawing, the shim 66 is substantially rectangular in shape, having one side of which being surmounted by a frostro triangularly shaped portion 68. The shape of the shim 64 is designed so as to conform with the shape of the reading head, more fully described below.

The shim 64 which, except for the boss 66, is essentially thin and flat, is within the bobbin aperture 22 in the frustro pyramid portion 24 of the bobbin 12 with the boss 66 extending into the shim aperture 26.

The armature of an electromagnetic transducer serves to cause the flux obtained from a record to flow therethrough and pass a coil. The flux induces a current in the coil.

The armature 70 of this invention comprises two

parts

72 and 74. The armature 70 may be constructed of materials commonly known in the art having high permeability. For example, the armature 70 may be made of a material made of 79 percent nickel, 5 percent molybdenum, and I6 percent iron. The shim 64 can be made of plastic. In the present embodiment the shim 64 is made of beryllium-copper. The shim 64 can also be made of a nonmagnetic stainless steel so that it can withstand wear. The first part or section 72 of the armature (FIG. 2) has a T-shaped construction with the leg 76 thereof extending at an obtuse angle, downwardly with respect to the crossbar 78 of the T. The leg 76 terminates with an inner gap taper 80 (FIG. 5), which is a common method of making the reading portion of an armature.

The crossbar 78 has a small rectangularly shaped section 82, extending in the same plane as the crossbar 78 and outwardly therefrom and opposed to the leg 76. There are bosses 84 (shown dotted in FIG. 2) at opposed ends of the crossbar 78. The function of these bosses 84 shall be more fully explained below.

The crossbar 78 rests across the bobbin 12 with the rectangular section 82 thereof resting upon a similarly shaped notch 86 in the rear wall 16 of the bobbin 12. Only a part of the notch 86 is visible in FIG. 2. The leg 76 of the first part 72 of the armature 70 is supported by the bobbin 12 in a notch 88 in the front wall 18. Upon being pressed against the bobbin 12 the first part 72 of the armature 70 will contact at its reading portion 90 with the shim 64. The second part 74 of the armature 70 is a substantially U-shaped member with one side 92 of the U being substantially longer than the other side 94 thereof. This second side 94 of the U has a T-shaped configuration. The crossbar 96 of the second side 94 is of substantially the same size as the crossbar 78 of the first part 72 of the armature 70. The opposed ends of the crossbar 96 have apertures 98. When the two crossbars 96 and 78 of the armature 70 are placed in registry, the bosses 84 and apertures 98 remain in registry and keep the reading tips aligned.

The first side 92 is inserted through the bobbin aperture 22 in such manner as it will press the shim 64 against the opposed wall of the bobbin aperture 22. The shim 64 is held securely by its boss 66 in the shim aperture 28 of the frustro pyramid section 26 of the bobbin 12.

As shown in FIG. 2, the second side 94 of the second part 74 of the armature 70 is inclined inwardly. In inserting the second part 74 into the bobbin l2 and over the first part 72 it is necessary to move back or spring the second side 94 into contact with the crossbar 78 of the first part 72 and lock in place by the engagement of the bosses 84 residing in the apertures 98. The pressure of the spring loaded U-shaped second part 74 together with the bobbin 12, holds the first part 72 of the armature 70 in place. The tip or reading portion 100 of the second part 74, taken together with the shim 64 and the reading portion 90 of the first part 72 from a substantially hemispherical reading head 102 (FIGS. 3, 4, and 5). The angular relationship of the first part 72 (as discussed above) and the frustro pyramidal shape 24 of the bobbin 12 serve to permit the relative motion of the reading head with respect to a record where the record is disposed on an uneven surface. In this design the reading material which may be for example a record, which may be for example a label attached to a piece of cloth, will not snag or catch on any part of the reading portion .102.

The transducer has a housing 104 (as shown in FIG. 1). The housing 104 has a top and

front wall

106 and 108, respectively, being substantially planar in shape and perpendicular to one another. A third wall 110 is opposed to the first two

walls

106 and 108 and lies at an angle thereto. At least a portion of this third wall 110 is curved at its uppermost portion ll2 thereof. The purpose of this curved portion 112 is more fully explained below.

Extending perpendicular to the first three

walls

106, 108, and 110, and forming therewithin a cavity 114 (FIG. 5) are two

side walls

116 and 118. These five

walls

106, 108, 110, 116, and 118 taken together comprise a general configuration of the housing 104. In general this is approximately a gunshape. The lower or muzzle" end of the housing 104 is closed by the combination of the bobbin l2 and armature 70. The combination of the armature 70 and bobbin 12 are held firmly in place without use of glue or other means by fingers 120 (FIG. 4). The fingers 120, may be resilient means such as springs or as shown in FIG. 5, molded as an integral part of one ofthe side walls 116.

In the embodiment disclosed, the coil 14 comprises a center tapped transformer. The output leads 60 of the transformer 14 are connected to tabs 52 on the clips 42 connected to the first arm 28 and the center tap is connected to the tab 52 of the clip 42 on the second arm 30 of the bobbin 12. Wires 122 for carrying the information transduced by the transducer 10 are secured to the

arms

28 and 30 and to the clips 42 by screws 124 (FIG. 5) secured in the

apertures

34, 36, and 38. The wires 122 form a part of a cable 126. These wires 122 may be secured to the clips 44 by soldering or other similar means rather than screws 124. If soldering is used, the wires 122 may be inserted through the

respective apertures

32, 34, and 36 and secured to the other side of the clip 42 so that

arms

28 and 30 act as strain relief.

Disposed within the housing 104, and extending perpendicularly to the third wall 110 is a cylindrically shaped post 128 (FIG. 3). The post 128 has therein an axially extending aperture 130 which may be internally threaded. The third wall 110 has therein an aperture 132 which is a registry with the aperture 130 of the post 128. This third wall 110 may be removable for purposes of assembly and repair of the transducer 10 and may be secured to the housing 104 by means of a screw 134 or similar means. Secured or molded to the post 128 are two metal terminals 135. Wires 122 from the cable 126 may be secured thereto, and may be used as a means for illumination. The means for illumination may be, for example, an electric lamp 136.

The lamp 136, which resides within the housing cavity 114 adjacent the top wall 106. The top wall 106 has therein an aperture 138 through which the lamp 136 may be seen. The aperture 138 may be in the shape, for example, of an arrow 140 (FIG. 1). The arrow 140 is intended to direct the user as to the proper direction of movement for the transducer. The aperture 138 in the top wall 106 may have therein a translucent material of clear or colored glass or plastic 142 (FIG. 5). Upon illumination, the arrow 140 indicates an operating state of a transducer 10. As shown in FIG. 3 wires 122 are connected to terminals to provide power to the lamp 136. The terminals 135 may be secured to a section adjacent the post 128 by means of molding or fixing by glue or similar means. The two wires of the lamp 136 are appropriately attached to respective terminals 135.

The cable 126 extends from the transducer 10 to a signal device 144 (FIG. 7). This device 144 may be any information receiving device as is commonly known in the art. The device 144 can, for example, provide a signal to the transducer for lighting the lamp. The signal (not shown) may indicate either an error condition or that the transducer 10 is receiving information correctly, or, in the alternative, that the transducer 10 is now in the state ready to receive new information. The signal to the lamp 136 may be given from the signal device 144 by manual means such as a switch thrown by an operator (not shown) or by automatic means either indicating proper operation or an error condition in which the transducer should not be used. Such a device 144 is well known in the art.

The

side wall

116 and 118 have therein depressions or dimples 146 (FIG. 1) at opposed sides of the transducer 10. These dimples 146 are placed so that the hand 148 of a user may conveniently grasp the transducer 10 (FIGS. 7 and 11). The thumb 150 and forefinger 152 may easily grasp and reside within the dimples 146 of the transducer 10. The curved third wall 110 can serve as a support for a third finger 154 of the hand 148. In normal use, the cable 126 may be held in the palm of the hand 148.

The prior art typical electromagnetic transducer as shown in FIG. 8. Such a transducer 200 generally takes the shape of a ring or may be somewhat flattened out, in the manner as shown. The transducer 200 may be constructed of a solid magnetic material, such as soft iron, nickel, cobalt, steel, ferrite, or similar material. The gap 202 may be provided when the material is formed into its particular shape or may be milled from the material itself after formation. In the back portion of the transducer 200 is placed a coil 204 which may be used alternatively for supplying writing current to the transducer 200 or for receiving or providing reading current therefrom, depending upon the mode of operation. Alternatively, two coils may be provided, one for reading and one for writing purposes.

The gap 202 is generally arranged (FIG. 9a) perpendicular to a face or reading surface 206 of the magnetic transducer 200. The transducer 200 may be aligned with a record bearing medium 208 in such a manner that the face 206 of the magnetic transducer 200 is parallel with the direction of relative movement of the transducer 200 and the record bearing medium 208. The gap 202 is placed perpendicularly to the surface of the record bearing medium 208. The gap 202 is placed in such a position as to cause the reading of the magnetized area 210 of the record bearing medium 208. A plurality of flux lines 212 are shown erninating from the left-hand portion of the magnetized area 210, extending about the magnetized area 210, above and below it, and closing to the right-hand portion of the magnetized area 210. One of these lines of flux 214 is shown entering the magnetic structure 216 of the magnetic transducer 200 at the gap 202. This line of flux 214 continues through the entire structure 216 and exits from the opposite side of the gap 202 from which it entered. Thereafter the line of flux 214 re-enters the magnetized area 210 in order to form a closed loop.

Flux, like current, follows the path of least resistance. Hence, it enters the magnetic structure 216 because the reluctance of the air space (or shim, if present) across the gap 202 is greater than the reluctance of the magnetic structure 216.

From this highly simplified representation, only a portion of the available fiux 212 from the magnetized area 210 is available for entry into the magnetic structure 216 transducer 200. The strength of the flux which is permitted to enter and which, as a result, induces readout current in the coil 204 is dependent on the strength of the magnetized area 210, the spacing between the record bearing medium 208 and the transducer gap 202, the width of the gap 202 along the direction of travel relative to the magnetized medium 206, the length of the gap 202 perpendicular to the direction of the travel, the speed of relative movement between the transducer 200 and the medium 208, and the composition of the magnetic structure 216 of the magnetic transducer 200.

When the transducer 200 is placed in a tilted position (FIG. 9b) such that the face 206 is no longer parallel to the lines of flux 212 the flux exiting from the magnetized area 210 is caused to travel a greater distance through the air in order to enter one of the faces of the gap 202 in the transducer 200. This will cause a greater reduction in the amount of flux which is permitted to enter the magnetic body of the transducer 200. The remaining flux is able to close in the air through the shorter distance. This failure of flux to enter the transducer 200 is due to the lower total reluctance of the air path as compared to a long air to pole piece path. This bypassing of the transducer 200 causes a greater reduction in the amount of flux available to the body of the transducer 200 and thus decreases the amount of signal available at the winding at the coil 204.

In order to minimize the possibility of such inclination of a gap with respect to the magnetized surface of a record to be read or recorded upon, it is the general practice in the prior art to rigidly mount a transducer and to control the path of movement of the magnetic medium so as to assure proper alignment and proper positioning of the gap with respect to the magnetic medium. It should be understood that in an ideal condition (FIG. 9a) write current supplied to the coil 204 is permitted to enter the magnetic medium and produce a greater strength recording that is possible in the tilted position (FIG. 9b). Turning now to FIG. 10, the transducer 10 of this invention is disclosed having a hemispherically shaped reading portion 102. It will be understood that the term hemispherically is used herein to denote a substantially spherically contoured surface as shown in greater detail in FIGS. 3, 4 and of the drawings. The gap 158 (defined by the shim 64 and the adjoining edges of the reading portions 90 and 100) of the two parts of the

armature

72 and 74, respectively, forms an arc on the spherical surface 102. Much of the difficulties of prior art devices are avoided by means of this unique design. As referred to above, rotating of the gap ofa prior art transducer relative to a record causes severe loss of signal strength.

The unique shape of the transducer permits relative rotation between the gap 158 and the record 160 in any one or combination of axes without significant loss of signal or incurring distortion. Thus, with a tip 102 having a radius of one thirty second of an inch and a one-half NRZ recording cell width of 0.0125 inch, a transducer 10 of this construction may read successfully during relative movement (arrow 62) and have relative rotation or positioning with respect to the record 160 about an axis which is both perpendicular to the surface of the record 160 and to the lines of flux to :30" (FIG. 10a), with respect to an axis perpendicular to the lines of flux about an axis which is parallel the surface of the record 160 and parallel to the lines of flux to 145 with respect to an axis perpendicular to the record surface (FIG. 10b), and about an axis which is parallel the record surface and perpendicular to the lines of flux to :t30 with respect to an axis perpendicular to the surface of the record (FIG. 10c). It is to be understood that the third axis of rotation, which is perpendicular the lines of flux and parallel the record 160 (FIG. 100), the axis is substantially proximate the record. Thus, in FIG. 10c the axis passes through the reading portion 102. In addition, relative rotation may be considered the same as positioning. That is, that the head of this construction and the record can assume a fixed position relative to one another about any of the axes and the transducer will produce a signal having a substantially constant or average strength and shall be free from distortion or noise. One advantage of this design is that the user can hold such a transducer in his hand (FIG. 7) and produce acceptable signals although the hand causes the transducer to move or be positioned about the above-noted axes. It has been found that the degrees of movement or rotation are sufficient to permit handheld use.

The transducer of this invention represents an improvement over the transducer described in copending application Ser. No. 126,602 by Richard .I. LaManna and Alan K. Jensen, entitled Magnetic Transducer". It has been observed that the transducer of that invention is limited in skew rotation (rotation about the axis which is perpendicular to the record and to the lines of flux). In addition it is much more complicated in construction in that the gap must be carefully inscribed on the surface of a keeper over a long length thereof. In addition, small cell recording mitigates against flexibility in movement.

Turning now to other features of the transducer of this invention, it will be noted that the top wall 106 of the transducer 10 has therein an arrow 140. This arrow indicates the preferred direction of movement as determined by the signal device 144. This direction is dependent upon the ability of the device 144 to interpret the information received. Transducers in general whether they be magnetic, optical, or the like, are not believed to have such an arrow indication thereon.

Another aspect of the invention is that of dimples 146 (FIG. 1). These dimples are located in the first and

second side walls

116 and 118, respectively. It should be noted that the first and

second side walls

116 and 118 lie in imaginary planes parallel to one another. As noted earlier, the general configuration of the transducer 10 is generally gun-shaped. Thus the user of the transducer will naturally grasp the transducer with the fingers of the hand falling into the dimples 146. The gun-shape of the transducer 10 is also adapted to accommodate the fingers of the hand as shown in FIG. 7.

Turning to another aspect of this invention it should be noted that in FIG. 2 the T-shaped construction of the two-

part armature

72 and 74 have enlarged or T-shaped portions. The

armature parts

72 and 74 enable the armature to be placed together. However, the enlarged area presents such a greater area that, in relation to any possible spacing or gapping due to the joining of the two parts together, there is relatively little or no loss of flux at the joining part. This is believed to be an advantage over the prior art devices for ease of construction.

Further, the crossbar portions, the outer portions thereof are employed to secure to the two parts together to form a single armature. By securing the two T portions by the boss and aperture combination the flux paths are not disturbed. Clearly these two parts may be joined together by screwing, gluing, or similar means. However, the boss and aperture combination provides an efficient means of joining the two parts together as will be more fully explained below.

The bobbin described herein and shown more clearly in FIG. 2 with its frustro pyramidal shaped front wall 24 in assembly with the armature 70 provides a guide or protective end as the tranSducer reading portion 156 of the armature 70 is passed over a label 160. See FIGS. 6 and 7. In assembly of the armature 70 and bobbin 12 of the transducer 10 it should be noted that the second part 74 is inserted into the apertures 22 and the second part 74 is spring loaded onto the first part 72 and thereby holding both in place and at the same time holding the shim 64 locked into position with the boss of the shim 66 fitted into the shim aperture 26. Thus, without means of screws, or glue, or other securing means and by virtue of resiliency of joining parts, the entire three elements are held together. In the same manner, the clips 42 are inserted into the

arms

28 and 30. The only means requiring to actually join one element to another by soldering or screwing is that of the joining of the wires of the cable 126 and the wires of the coil 14. The wide surface area of the clips 42 serves to dissipate heat when soldering. It is believed that most connectors used in combination with bobbins are of a narrow type having a small relative area compared to the wire used in such a bobbin and to the area proximate the bobbin. Thus, heat applied to solder the coil wires onto such clips or terminals will invariably injure the wire, the insulation, on the wire, and/or the bobbin itself. The clip-on form of these terminals 42 by means of the flange 58 insures quick and easy assembly as of the combination of the armature, bobbin, and shim.

The use of a means of illumination such as the light bulb 136 rovides the means of indication as to when the device is operative or not. This lighting is controlled by an error or an error signal from the device 144 as is commonly known. By this means the user receives an indication from the device 144 which tells the user whether or not the transducer should be used. Thus if the light is lit it can be used to indicate that to the user that the transducer is receiving the information or conversely that the transducer has not received the proper information and the transducer should be moved over the record again or that the transducer is now ready to receive additional information. By combining the light with the arrow the transducer provides an indication of the state of readiness or usefulness of the transducer and its direction of use to the user. Except for the soldering or joining of wires to terminals and the screwing of the curved third wall 112 to the transducer it should be noted that the entire transducer is assembled without means of screwing, soldering, or the like. Thus the bobbin bottom wall 24 of the bobbin 12 serves as the muzzle or transducing end of the transducer 10 and is held in place by the fingers 120 on the side walls of the inner side wall of the cavity 114 of the transducer 10. Thus, there is described herein a novel magnetic transducer having many features applicable to other types of transducers and which is economical in construction.

What is claimed is:

l. A manually supportable and positionable magnetic transducer for use with a magnetic record having lines of flux arranged in an intended reading path comprising:

a. a housing to be held in a hand;

b. a reading head and having tip member with a hemispherically shaped reading portion extending without the housing for traversing a magnetic record, said reading portion having a gap defining an are on its surface; and

. coil means about said reading head for providing an electrical signal;

. said reading portion being so proportioned such that only a small portion of said gap will be aligned tangent to the record during movement of said transducer with respect to the record thereby limiting the strength of a signal induced in said coil means and providing a substantially undistorted signal of consistent strength when said gap is rotated or positioned with respect to the record about a first axis which is substantially perpendicular to both the lines of flux and the surface of the record, about a second axis which is substantially parallel to the surface of the record and substantially parallel to the lines of flux, and about a third axis which is substantially parallel to the surface of the record and substantially perpendicular to the lines of flux.

2. A handheld magnetic transducer for use with a magnetic record having lines of flux arranged in an intended reading path comprising:

a. reading means;

b. coil means disposed about said reading means for providing an electrical signal during relative movement between the transducer and lines of flux on a record; and

c. said reading means including a gap and two opposing contoured tip members in sandwiched array to form a sub stantially spherical like contoured surface defining a substantially hemispherical reading portion for said reading means, said reading portion being such that only a small portion of said gap will be aligned tangent to the record during movement of said transducer with respect to the record thereby limiting the strength of a signal induced in said coil means and providing a substantially undistorted signal of consistent strength.

Claims

1. A manually supportable and positionable magnetic transducer for use with a magnetic record having lines of flux arranged in an intended reading path comprising: a. a housing to be held in a hand; b. a reading head and having tip member with a hemispherically shaped reading portion extending without the housing for traversing a magnetic record, said reading portion having a gap defining an arc on its surface; and c. coil means about said reading head for providing an electrical signal; d. said reading portion being so proportioned such that only a small portion of said gap will be aligned tangent to the record during movement of said transducer with respect to the record thereby limiting the strength of a signal induced in said coil means and providing a substantially undistorted signal of consistent strength when said gap is rotated or positioned with respect to the record about a first axis which is substantially perpendicular to both the lines of flux and the surface of the record, about a second axis which is substantially parallel to the surface of the record and substantially parallel to the lines of flux, and about a third axis which is substantially parallel to the surface of the record and substantially perpendicular to the lines of flux.

2. A handheld magnetic transducer for use with a magnetic record having lines of flux arranged in an intended reading path comprising: a. reading means; b. coil means disposed about said reading means for providing an electrical signal during relative movement between the transducer and lines of flux on a record; and c. said reading means including a gap and two opposing contoured tip members in sandwiched array to form a substantially spherical like contoured surface defining a substantially hemispherical reading portion for said reading means, said reading portion being such that only a small portion of said gap will be aligned tangent to the record during movement of said transducer with respect to the record thereby limiting the strength of a signal induced in said coil means and providing a substantially undistorted signal of consistent strength.