US3066200A

US3066200A - Speaker device

Info

Publication number: US3066200A
Application number: US754449A
Authority: US
Inventors: Walter A Pavlak
Original assignee: WILLIAM WARD JACKSON
Current assignee: WILLIAM WARD JACKSON
Priority date: 1958-08-11
Filing date: 1958-08-11
Publication date: 1962-11-27
Anticipated expiration: 1979-11-27

Description

W. A- PAVLAK SPEAKER DEVICE Nov. 27, 1962 2 Sheets-Sheet 1 Filed Aug. 11, 1958 INVENTOR. Walter Alexander Povlak BY M yMwYa Md% ATTORNEYS Nov. 27, 1962 w. A. PAVLAK 3,066,200

SPEAKER DEVICE Filed Aug. 11, 1958 2 Sheets-Sheet 2 FIG? - INVENTOR. n Walter Alexander Pavlok Q 8 g wiwmww ATTORNEYS United States Patent 3,066,200 SPEAKER DEVICE Walter A. Pavlak, Newark, N..I., assignor to William Ward Jackson, Short Hills, NJ. Filed Aug. 11, 1958, Ser. No. 754,449 8 Claims. (Cl. 179--115.5)

My invention relates to the transmission and reproduction of sound and in particular provides a transducer for converting sound into electrical signals or for converting audio frequency electrical signals into sound. The transducer of my invention is thus useful as a microphone, earphone or a loudspeaker.

In the reproduction of sound and particularly in reproducing music it is of course highly desirable to provide a speaker not only capable of reproducing the original sound without distortion but also having a frequency response extending throughout the audible range. Heretofore it has generally been necessary to provide a plurality of speaker devices for different portions of the audio frequency range in order that the entire audible range will be accurately reproduced. Such plural speaker systems nesessarily involve mechanical or electrical frequency cross-over devices for separating the original sound into the various frequency ranges to be reproduced by the individual speaker units. As a consequence, highly complicated and expensive speaker systems are required for obtaining so-called high fidelity" sound reproduction. More particularly in the reproduction of sound by the so-called binaural system two separate speaker systems must be employed thus doubling the amount of equipment necessary for high fidelity reproduction. Many times, moreover, it is desirable to provide good quality sound reproduction under circumstances interfering with the activities of others. At present the employment of earphones to prevent such interference is unsuitable where high fidelity reproduction is required due to the high cost of providing the plural earphone system necessary to obtain full audio frequency range reproduction.

It is a principal object of my invention to provide a simple speaker device for reproducing electrical signals as sound having a wide frequency response range extending throughout the principal audible range. It is also an object of my invention to provide such a speaker device which can be constructed in a relatively small space such that it can be suitably employed as an earphone. It is still a further object of my invention to provide a speaker device which is simple in mechanical construction and which can be connected directly to the output of an audio amplifier without the employment of electrical or mechanical cross-over networks. It is yet another object of my invention to provide such a speaker device which is inexpensive to manufacture and which is extremely light in weight.

While the general object of my invention is to provide a speaker device for reproducing sound, the same device with minimum modification provides an excellent microphone for faithfully converting sound extending throughout the principal audible range into electrical signals which can be simply connected to the input of an audio amplifier, recording equipment or other conventional devices.

In keeping with these general purposes my invention thus provides a speaker device which can suitably be employed for high fidelity sound reproduction. In pairs, such speakers can be employed for binaural sound reproduction when connected to separate amplifiers. Simulated binaural effects can be developed employing a pair of such speaker devices as earphones where a capacitance is included in one of the earphones to permit control of the bass and treble response in such earphones. As will be evident later, the speaker device of my invention can ice also be constructed to provide a limited frequency range accentuating the treble response or bass response as desired. Thus, simulated binaural effects can be obtained employing one earphone constructed to emphasize the bass frequency range of the music and one constructed to emphasize the treble range. It is also possible, employing the speaker device of my invention in multiples, to provide a thin loudspeaker which can be hung against a wall. A picture frame" speaker, thus constructed using the device in multiples, can be provided having a thickness of one inch or less and which is capable of reproducing faithfully the original sound throughout the audible range.

These and other objects of my invention which will become more apparent hereinafter are essentially obtained by positioning a pair of magnets spaced from each other such that a pole face of one and a pole face of the second having opposite polarity lie in a common plane spaced slightly from each other to define an elongated narrow magnetic gap. A thin diaphragm of non-magnetic material is supported extended across and along the magnetic gap in a free floating position, and an elongated conductor is affixed to the diaphragm extending lengthwise of the gap between the two pole faces.

When the speaker is to be employed for sound reproduction the ends of the conductor are connected to a conventional low impedance output of an audio amplifier such that electrical output signals of the amplifier are passed through the elongated conductor to cause the conductor together with the diaphragm to which it is affixed to vibrate toward and away from the magnetic gap corresponding such electrical output signals. The movement of the diaphragm thus sets up sound waves reproducing the original sound used to generate the signals in the amplifier.

When the speaker device of my invention is to be employed for sound transmission, however, the ends of the conductor are connected instead to a conventional low impedance input of an audio amplifier. Thus, when the diaphragm is vibrated by sound waves which impinge against it, the movement of the elongated conductor in the magnetic gap generates electrical currents in the conductor which correspond to the impinging sound waves and are coupled to the input of the amplifier to drive the amplifier.

In a more specific aspect I employ a system of magnets arranged to provide a plurality of such magnetic gaps extending parallel to each other and arrange the conductor, as it leaves one gap, to turn on itself and enter the next adjacent gap, thus permitting the employment. of a relatively square or round diaphragm of which almost every portion is actuated simultaneously by movement of the conductor under the influence of the application of electrical signals.

In another aspect, particularly where the speaker device of my invention is employed as a microphone, I have found it advantageous to provide a second pair of magnets similarly spaced from each other, such that a pole face of one and a pole face of a second having opposite polarity lie in a common plane spaced slightly from each other to define a second elongated narrow magnetic gap. The second pair of magnets is positioned confronting the first pair of magnets with pole faces of like polarity spaced closely together. Thus, the two elongated narrow magnetic gaps confront each other with their magnetic force lines lying in the same direction. The diaphragm is supported extended across the two gaps and lengthwise between the confronting pole faces of the two pairs of magnets with the elongated conductor extending lengthwise between the two confronting magnetic gaps. This arrangement is possible because, surprisingly, accuratereprodnction can be obtained if the diaphragm is oriented such that the sound waves which are to be converted to electrical signals are directed into the speaker device edgewise of the diaphragm.

For a more complete understanding of the practical application of the principles of my invention, reference is made to the appended drawings in which:

FIGURE 1 is a diagrammatic illustration of the underlying principle of operation employed in my speaker;

FIGURE 2 is a cross-section through a practical construction embodying the principles of my invention to provide an earphone type speaker;

FIGURE 3 is a section taken at line 3-3 in FIGURE 2;

FIGURE 4 is an exploded view of a portion of the device shown in FIGURES 2 and 3;

FIGURE 5 is an exploded view of another device constructed in accordance with the principles of my invention;

FIGURE 6 is an elevational view of the assembled construction of FIGURE 5; and

FIGURE 7 is a cross-section taken at line 7-7 in FIG- URE 6.

Referring more particulary to FIGURE 1, the reference numeral 10 indicates the basic device of my invention which is schematically shown connected to the output transformer 11 of a typical conventional audio amplifier. Speaker device 10 basically includes a pair of bar magnets 12 and 13 constructed to any suitable magnetic substance having high coercive force and rententivity such as Alnico No. S.

Magnets 12 and 13 are erected on a suitable fiat surface 9 to which they are afiixed to hold them parallel and spaced a short distance from each other with the south pole face 12a on the upper side of magnet 12 and with the north pole face 13a on the upper side of magnet 13. Thus at their upper ends, magnets 12 and 13 define an elongated narrow magnetic gap 14.

Four non-magnetic posts 15 affixed at their lower ends 0 on surface 9 are erected with one post 15 adjacent each outer corner of the rectangular solid space occupied by magnets 12 and 13. Posts 15 have approximately the same height as magnets 12 and 13 and at their upper ends carry short cushions 16 of sponge rubber or similar relatively elastic and freely compressed and stretched material. Cushions 16 are cemented at their lower ends to the upper ends of posts 15 and extend slightly above the pole faces 12a and 13a.

The thin diaphragm 17, in the illustrated case of rectangular shape, is positioned horizontally above the upper ends 12a and 13a of magnets 12 and 13 and is cemented at its corners on the upper ends of cushions 16 which thus support diaphragm 17 spaced slightly above the upper ends 12a and 13a of magnets 12 and 13 with diaphragm 17 extended across and along magnetic gap 14. Diaphragm 17 is constructed typically of polyvinyl chloride sheet material but can be made of almost any non-magnetic material such as wood, paper, cloth, glass or the like. The material of construction of diaphragm 17 can be either soft or hard, it can be relatively elastic or relatively inelastic, it can be freely flexible or it can be quite stiff. Depending upon the variations of these characteristics different frequency response patterns can be obtained. A

v treble response is accentuated by harder, more inelastic and stiffer materials, while bass response is accentuated by softer, relatively more elastic and flexible material.

A ribbon conductor 18 is cemented to the upper surface of diaphragm 17 and extends lengthwise over gap 14. Preferably conductor 18 has the flat ribbon-shaped appearance shown in FIGURE 1 and is aligned along its edges with the adjacent edges of the upper surfaces 12a and 13a of magnets 12 and 13 between which magnetic gap 14 is defined. The employment of a fiat ribbon type conductor is not essential, however, and wire conductors can also be employed, however with less efiiciency. Condoctor 18 in the illustrated case is a strip of aluminum foil cemented to diaphragm 17. It, however, obviously can be applied to diaphragm 17 in the same manner as 4 printed circuits are manufactured; it can be heat-sealed between a pair of thin sheets of material from which diaphragm 17 is constructed, and it can be applied in other obvious ways.

The ends of conductor 18 are connected to flexible electrical

lead wires

19 and 20 which connect conductor 18 in series with the low impedance secondary winding 11a of output transformer 11. The impedance of winding 11a is not particularly critical and typically will range up to several hundred ohms but typically will be on the order of 2 to 8 ohms.

In operation where transformer 11 is the output transformer of an amplifier connected to a source, such as a phonograph, providing electrical signals in the audio frequency range, the sound is reproduced by vertical vibration of diaphragm 17 as conductor 18, by reason of the passage of electrical current through it, is caused to move vertically in magnetic gap 14. It will be selfevident that the closer to gap 14 that conductor 18 is positioned, the lesser the distortion introduced will be. However, conductor 18 is limited in its position relative to gap 14 by the fact that diaphragm 17 must have room to vibrate freely. Alternatively, transformer 11 can be an input transformer of a conventional audo amplifier, in which case winding 11a will be the primary winding and typically will have a relatively low impedance. In the latter case, sound impinging against diaphragm 17 will cause vibration of conductor 18 vertically in magnetic gap 14. This movement will generate electric currents in conductor 18 which, being coupled by leads 19 and 20 to primary winding 11a of transformer 11, will drive the audio amplifier to which transformer 11 is connected. Thus sound striking diaphragm 17 Will be reproduced as an electric signal which can be utilized to drive conventional audio equipment.

FIGURES 2, 3 and 4 illustrate a practical arrangement of a speaker constructed in accordance with my invention, having particular utility as an earphone. In FIGURES 2, 3 and 4 the earphone of my invention is designated basically by the reference numeral 30 and is suitably housed in a short cylindrical casing 31 having one end closed by an integral bottom 32 and externally threaded at the other end as indicated by the reference numeral 33. A perforated cap 34 is threadedly engaged with casing 31 received on threads 33 to close the housing of ear- 6 phone 30. Casing 31 and cap, i.e., earpiece 34 are suitably constructed of hard plastic material such as a phenolic resin or other suitable non-magnetic material.

Casing 31 contains a modified version of speaker device 10 providing a preferred construction for obtaining maximum efiiciency in sound reproduction while at the same time obtaining full frequency range response. To be more specific, casing 31 is provided with a system 36 of'U-shaped, i.e. channel shaped, magnets 35 which, as seen more clearly in FIGURE 4, are disposed in staggered arrangement to define eight elongated narrow magnetic gaps 37 of the type denoted by reference numeral 14 in FIGURE 1.

The magnet system 36 is thus composed of twentyeight identical channel-shaped magnets 35 arranged in seven parallel rows with four magnets in each row. In each row the four magnets 35 are disposed in a line presenting alternating north pole faces 35a and south pole faces-35b. The four magnets 35 in each row are spaced from each other a distance identical to the spacing of the opposite pole faces 35a and 35b of each individual magnet 35. The seven rows of magnets, as indicated above, are parallel and each adjacent pair of rows are arranged with their respective magnets closely adjacent but staggered lengthwise such that in any given pair of adjacent rows of magnets the channel centers of the magnets 35 in one row register with the spaces between magnets in the other row. In each adjacent pair of rows, however, the pole faces of the magnets are aligned. Accordingly,

the magnets in each adjacent pair of rows are disposed in reversed orders of polarity. In any adjacent pair of rows of magnets, the pole face of a magnet in one row adjacent the pole face of another magnet in the second row are not only aligned but have identical polarity. Thus, the magnet system 36 includes parallel lines of pole faces 35a and 35b which define between them eight elongated parallel magnetic gaps 37 extending perpendicularly to the parallel rows of magnets 35. Along one side of each gap 37, magnets 35 all present their north pole faces 35a, and along the other side of each gap 37, magnets 35 all present their south pole faces 35b.

The system 36 of magnets 35 is maintained in position on a brass plate 38 (see FIGURE 2) to which magnets 35 are affixed on their under sides by means of small machine screws 39. Plate 38 also supports four dia phragm support posts 40 which on their under ends (in FfGURE 2) are similarly aflixed to brass plate 33 by means of small machine screws 41. Posts 40 are identical in height with magnets 35, and on their upper ends are provided with short sponge rubber cushions 42. Posts 40 are, moreover, located at the four corners of the space occupied by magnet system 36 and are constructed of non-magnetic material, such as polystyrene rod.

A diaphragm 43 of generally rectangular shape provided with corner ears 44 (see FIGURES 3 and 4) is positioned across magnet system 36 above pole faces 35a and 35b and gaps 37 with cars 44 resting on cushions 42 to which diaphragm 43 is cemented to retain it in position. Diaphragm 43 supports a flat metallic ribbon conductor 45 which is cemented on the upper surface of diaphragm 43 following a tortuous path including eight parallel straight portions 45a which are aligned over gaps 37 and which are inter-connected at alternate pairs of adiaccnt ends by connecting portions 45b. Thus the instantaneous electrical current flowing in a given direction through conductor 45 is flowing in alternating directions in adjacent straight portions 45a. The free ends of conductor 45 are electrcally and mechanically connected to

flexible lead wires

46 and 47, which terminate with

conventional lugs

48 and 49, respectively, for connections to the output of an audio amplifier.

The assembly of base plate 38, magnet system 36, diaphragm 43 and conductor 45 is positioned in the bottom 32 of casing 31 with base plate 38 resting against bottom 32 to which it is secured by means of screws 50, thus positioning diaphragm 43 adjacent the threaded end 33 of casing 31 over which perforated cap 34 is positioned. Leads 46 and 47 are brought through suitable

insulated bushings

51 and 52, respectively, mounted in the side Wall portion of casing 31.

In operation, lugs 48 and 49 are connected to the low impedance output of an audio amplifier in a conventional manner and earphone 30 is mounted in a head set, for example, by providing center bored bosses 53 on the exterior of casing 31 for receiving the pivot pins of the head set.

In a construction typified by FIGURES 2, 3 and 4 employing twenty-eight channel shaped Alnico No. 5 magnets ,5,, inch high, M inch across the poles and inch lengthwise of the gap with gap 37 & inch wide, in which the seven rows of magnets are spaced slightly to provide a gap 37 length of 2.3 inches, where diaphragm 43 was constructed of soft pliable polyvinyl chloride having a thickness of 0.0005 inch, in which conductor 45 is cut from equal thickness of aluminum foil exactly equal in width to the gap Width and in which diaphragm 43 was positioned one-eighth inch above the upper faces 35a and 35b of magnets 35, the earphone 30 driven by an 8 ohm tap on the output transformer of a conventional 10 Watt amplifier gave uniform reproduction throughout a frequency range of 40 to 12,000 cycles per second, With some attenuation below and above that range.

It should be pointed out that it is highly essential that diaphragm 43 be floated. Damping is undesirable and accordingly, as illustrated, the diaphragm is mounted on sponge rubber cushions. Any other type of diaphragm mounting which would provide a minimum of damping effect could, of course, be substituted. Small strips of plastic or fabric could obviously be employed. The housing is unessential from an acoustical standpoint, but of course is desirable in order to present a neat and attractive device and also in order to prevent damage to the delicate diaphragm employed. The housing suitably is constructed of a non-magnetic material to simplify problems of insulation and disturbance with the electrical circuit. The conductor for the same reason should be constructed of non-magnetic conductor material such as aluminum or copper.

As indicated above, variation in the material of construction of the diaphragm can be employed to produce varied frequency responses. The soft, pliable polyvinyl chloride sheet described above gives an overall wide frequency response. Stiller materials, having harder surfaces, such as cellulose acetate sheet, will tend to give a response peaked in the treble range, While softer materials, on the other hand, will tend to emphasize bass response.

Also as indicated above, the speaker device of my invention has practical utility as a microphone, as, for example, illustrated in FIGURES 5, 6 and 7. Referring to these figures, the reference numeral 60 designates a microphone which has been constructed in accordance with my invention, and which includes fundamentally a first magnet system 61, a diaphragm 62 including an imbedded conductor 63, and a second magnet system 64.

Magnet system 61, as is seen more clearly in FIGURE 5, is composed of twenty-eight channel-shaped magnets 65 disposed in seven parallel rows of four in a manner identical to the disposition of magnets 35 in magnet system 36 described with reference to FIGURES 2, 3 and 4, and thus defining eight parallel elongated narrow magnetic gaps 66. Along one side of each gap 66 magnets 65 all present their north pole faces 65a, and along the other side of each gap 66 magnets 65 all present their south pole faces 65b. Magnet system 61 is secured to a circular brass disk 67 by means of small machine screws 68 in the same manner as magnets 35 are secured to brass base plate 68 of earphone 30.

Magnet system 64 is composed of twenty-eight channel-shaped magnets 69 which are disposed in seven parallel rows of four in a manner exactly complementary to magnet system 61, such that when the two magnet systems are presented in a position confronting each other, a magnet 65 confronts each magnet 69 with the north pole face 65a of each magnet 65 confronting the north pole face 69a and with the south pole face 65b of each magnet 65 confronting the south pole face 69b of a magnet 69. Similarly, the eight parallel elongated narrow magnetic gaps 70 defined by magnets 69 thus can be presented confronting and aligned with the eight magnetic gaps 66 of magnet system 61 with the lines of force of magnetic gaps 70 running in the same alternate directions as the lines of force of magnetic gaps 66. Magnet system 64 is similarly affixed to a circular brass plate 71 by means of small machine screws 72.

Diaphragm 62 includes two

sheets

73 and 74 of soft, pliable film material such as saran, cut to identical shape and size. Each

sheet

73, 74 is thus generally rectangular, having dimensions slightly greater than the width and breadth of complementary magnet systems 61, 64. At each

corner sheets

73, 74 are provided with small extensions or tabs denoted by the reference numerals 73a. 73b, 73c, 73d in the case of sheet 73, by the

reference numerals

74a, 74b, 74c, 74d in the case of sheet 74.

Conductor 63 consists of a fiat ribbon of aluminum foil including eight parallel straight lengths 63a interconnected in series by seven connecting strips 63b which connect alternate pairs of ends of straight portions 63a. The free ends of conductor 63 are electrically and mechanically connected to

flexible lead wires

75, 76 which terminate with

conventional lugs

77, 78, respectively, for connection to the input terminals of an audio amplifier.

Conductor 63 is assembled with diaphragm 62 by first cementing conductor 63 to the face of one

sheet

73, 74 with straight portions 63a parallel to one pair of opposite sides of the sheet and with connecting portions 63b closely adjacent the other pair of opposite sides of the sheet. The

second sheet

73, 74 is then cemented to the first sheet on which conductor 63 has been previously cemented, so that conductor 63 is sandwiched between

sheets

73, 74 and so that

sheet

73, 74 are perfectly aligned with

tabs

73a, 73b, 73c, 73d being aligned with

tabs

74a, 74b, 74c, 74d. Each straight portion 63:: of conductor 63 is slightly longer than

magnetic gaps

66, 70 and is slightly narrower than such gaps. Straight portions 63a are, moreover, spaced exactly as

magnetic gaps

66, 70 are spaced in their respective magnet system 61, 64.

Microphone 60 is assembled by means of four posts 79, four posts 80, four sponge rubber cushions 81, four sponge rubbercushions 82 and two spacer tubes 83. Posts 79 are constructed of non-magnetic material such as polystyrene, brass or the like, and have a length exactly equal to the height of each magnet 65 (measured from the pole faces to the opposite face of the channel portion connecting the poles). Posts 79 are secured to brass plate 67 by means of small machine screws 84 just beyond the four corners of magnet system 61 such that the ends of posts 79 remote from brass plate 67 lie in approximately the plate of pole faces 65a, 65b. Cushions 81 are then cemented on such ends of posts 79, and diaphragm 62, previously assembled with conductor 63 as described above, is then positioned with

tabs

73a, 73b, 73c, 73d resting against cushions 81 to which the tabs are thereupon cemented. In such operation of assembling diaphragm 62, care should be taken that each straight portion 63a of conductor 63 is centered 1 lengthwise over a magnetic gap 66 with connecting portions 63b lying just beyond the ends of gaps 66.

Posts 80 are similarly of non-magnetic material and approximately equal magnets 69 in height. Posts 80 are secured to base plate 71 similarly adjacent the four corners of magnet system 64 and carry cushions 82 cemented to their outer ends which lie approximately in the plane of pole faces 69a, 6%. Base plate 71, with magnet system 64, posts 80 and cushions 82, is then positioned on the side of diaphragm 62 opposite magnet system 61 with cushions 82 being cemented to diaphragm 62 at

tabs

74a, 74b, 74c, 74d, and with magnet system 64 exactly aligned with magnet system 61 such that pole faces 69a confront pole faces 65a, pole faces 69b confront pole faces 65b and magnet gaps 70 confront magnetic gaps 66. Thus, diaphragm 62 is positioned floating on cushions 81 and 82in the narrow space between the confronting magnetic systems 61, 64.

Since cushions 81 and 82 do not hold the assembly rigid, spacer tubes 83 are providedto secure base plate 67 to base plate 71. Thus, spacer tubes 83 are preferably constructed of non-magnetic material, such as brass, and have a length equal to the combined lengths of a post 79, a cushion 81, a cushion 82 and a post 80, plus the thickness of diaphragm 62. Spacer tubes 83 are positioned between plates 67 and 71 on opposite sides of magnet systems 61, 64 slightly beyond the edges of diaphragm 62, and are held in place by means of rivets 85.

The assembled microphone 60 desirably can be encased with copper or other non-magnetic wire mesh and is provided with suitable external mountings as desired. It will be apparent that sound passing between side plates 67, 71 of microphone'60 will cause vibration of diaphragm 62 and consequently cause conductor 63 to move laterally through the fields of force set up by confronting

magnetic gaps

66, 70. Thus, electric currents will be generated in straight portions 63a of conductor 63 which will have the same instantaneous polarity in conductor 63 because of the alternate directions of flux in adjacent gaps 66 and their confronting adjacent gaps 70, and be cause of the alternate end connections 6312. Accordingly, currents generated in conductor 63 by movement of diaphragm 62 will produce an electric signal at

lugs

77, 78, which, when connected to a suitable low level, low impedance input of an audio amplifier, can be utilized to drive the amplifier.

In a microphone having the same general magnet dimensions described above with respect to earphone 30, and also having the same diaphragm-to-magnet spacing, as in the case of earphone 30, a pro-amplifier of the type employed with reluctance-type phonograph cartridges will generally be required, however preferably without equalization normal required in such pre-amplifiers to compensate for bass attentuation and treble emphasis usually employed in phonograph recording.

I claim:

1. A transducer which includes a first magnetized body defining a first pole face, a second magnetized body defining a second pole face of polarity opposite that of said first pole face, said first and second magnetized bodies being disposed with said first and second pole faces spaced apart and extending adjacent each other in a common plane defining an elongated, narrow magnetic gap with said first and second magnetized bodies disposed to one side of said common plane, a thin diaphragm of non-magnetic material, means supporting said diaphragm in fioating position extended across and along said gap on the other side of said common plane and spaced a short distance from said pole faces, and an elongated conductor positioned entirely on said other side of said common plane extended lengthwise of said gap aliixed between said pole faces to said diaphragm.

2. A transducer according to claim 1 in which said magnetized bodies constitute opposite end portions of a channel-shaped magnet.

3. A transducer according to claim 1 further includes a third magnetized body defining a third pole face of the same polarity as said first pole face, and a fourth magnetized body defining a fourth pole face of the same polarity as said second pole face, said third and fourth magnetized bodies being disposed spaced a short distance from said diaphragm on the side of said diaphragm opposite said first and second magnetized bodies with said third pole face confronting said first pole face, with said fourth pole face confronting: said second pole face, and with said third and fourth pole faces spaced apart and extending adjacent each other in a second common plane defining a second elongated, narrow magnetic gap confronting said first namedgap, said conductor being positioned entirely on the-side of said second common plane remote from said third and fourth magnetized bodies.

4. A transducer which includes a plurality of magnetized bodies, each defining a pole face, said plurality of magnetized bodies being disposed with their respective pole faces parallel, spaced apart and extending adjacent each other in a common plane with said magnetized bodies disposed to one side of said common plane, said pole faces being of alternating polarity thereby defining a plurality of parallel, elongated, narrow magnetic gaps, a thin diaphragm of non-magnetic material, means supporting said diaphragm in floating position extending across and along said gaps on the other side of said common plane and spaced a short distance from said pole faces, and an elongated conductor positioned entirely on said other side of said common plane afiixed to said diaphragm including a plurality of straight portions each extending lengthwise of one said magnetic gap between the adjacent pole faces defining said one gap and a plurality of end connections serially connecting alternate pairs of adjacent ends of said straight portions whereby said straight portions are interconnected in series.

5. A transducer according to claim 4 in which said magnetized bodies constitute opposite end portions of a plurality of channel-shaped magnets.

6. A transducer according to claim 4 in which said conductor is ribbon shaped.

7. A transducer which includes a first magnetized body defining a first pole face, a second magnetized body defining a second pole face of polarity opposite that of said first pole face, a third magnetized body defining a third pole face of the same polarity as said first pole face, and a fourth magnetized body defining a fourth pole face of the same polarity as said second pole face, said first and second magnetized bodies being disposed with said first and second pole faces spaced apart and extending adjacent each other in a common plane defining an elongated, narrow magnetic gap with said first and second magnetized bodies disposed to one side of said common plane, a thin diaphragm of non-magnetic material, means supporting said diaphragm in floating position extended across and along said gap on the other side of said common plane and spaced a short distance from said pole faces, said third and fourth magnetized bodies being disposed spaced a short distance from said diaphragm on the side of said diaphragm opposite said first and second magnetized bodies with said third pole face confronting said first pole face, with said fourth pole 'face confronting said second pole face, and with said third and fourth pole faces spaced apart and extending adjacent each other in a second common plane defining a second elongated, narrow magnetic gap confronting said first named gap, and an elongated fiat conductor positioned entirely between said first named and said second common planes extending lengthwise of said gaps afiixed between said pole faces to said diaphragm.

8. A transducer which includes a plurality of magnetized bodies each being respectively disposed with a pole face parallel with a pole face of each of said magnetiezd bodies in a common plane, said magnetized bodies being disposed on one side of said common plane, the pole faces in said common plane being disposed adjacent and spaced apart in pairs of opposite polarity, said pairs of pole faces each defining therebetween one of a p1urality of elongated, narrow, magnetic gaps, a thin diaphragm of non-magnetic material, means supporting said diaphragm in suspended position extending across and along said gaps on the other side of said common plane and spaced a short distance from said pole faces, a plurality of fiat conductors contacting with and afiixed to said diaphragm and lying in a plane parallel thereto also positioned entirely on the other side of said common plane, each conductor extending lengthwise of one of said magnetic gaps between one of said pairs of adjacent pole faces, a first terminal and a second terminal, each of said conductors having a first end and a second end, said conductors being interconnected between said first terminal and said second terminal, said first end of each of said conductors being connected in closer electrical relationship to said first terminal, and said second end of each of said conductors being connected in closer electrical relationship to said second terminal, the orientation of each of said conductors and the pair of magnetized bodies associated therewith in respect of said first end and said second end of said conductor and in respect of the polarity of each of said pair of magnetized bodies associated therewith, being identical as viewed from a point on a normal to said common plane.

References Cited in the tile of this patent UNITED STATES PATENTS 496,602 Field May 2, 1893 1,523,540 Hecht Jan. 20, 1925 1,542,922 Thompson June 23, 1925 1,604,532 Riegger Oct. 26, 1926 1,704,511 Nakken Mar. 5, 1929 1,815,564 High July 21, 1931 2,360,796 Roberton Oct. 17, 1944 2,404,798 Harry et a1 July 30, 1946 2,545,007 Schultheis Mar. 13, 1951 FOREIGN PATENTS 484,339 Germany July 30, 1924 Disclaimer 3,066,200.-Walter A. Pavlaic, Newark, NJ. SPEAKER DEVICE. Patent dated Nov. 27, 1962. Disclaimer filed Aug. 23, 1966, by the assignee, William Waml Jackson; the inventor assenting.

Hereby enters this disclaimer to

claims

3 and 7 of said patent.

[Ofiicial Gazette October 4,1966]