US1790528A - Ington - Google Patents

Description

Jan.-27, 1931. G. BABCOCK TELEPHONE RECEIVER Filed Oct. 6, 1 26 WELD I 0 0 0 w w 2 3wm N S 1 /l/. /3 3 6 Garrison Babcack Patented Jan. 27, 1931 GARRISON BABCOGK, F SEATTLE, WASHINGTON, ASSIGNOR.T0 AMERICAN TELE- CHRONOMETER ING'ION CQMPANY, OF EVERETT, WASHINGTON, ACORPORATION OF WASH- TELEPHONE RECEIVER Application filed October 6,1926.v Serial 110,139,810.

My invention relates to a telephone receiver unit andparticularly to a device adapted for use in loud speakers to energize a vibratory body for the reproduction of sound.

in part my present invention is a'continuation of my application Serial No. 1,052, filed June 26, I922, andin part it is an improvement upon my Patent No. 969,832.

It is an object of my invention to provide an electromagnetic structure having a minimum of magnetic reluctance, andapplying the magnetic force most effectively and concentratedly to a diaphragm.

Afurther object is the provision of an electromagnetic unit for such purpose, and of a diaphrag'un or armature for use in con nection therewith by means of which a diaphragm is mounted between two opposed poles and is thus neutrally positioned in a 1 strong field, to be energized sensitively by slight variations in the magnetic flux through said field.

A further object is the provision of a simple diaphragm in which the central. portion is placed in a highly stressed condition, whereby its natural period is above the range of audibility, supported within a flexible ring from a suitable support.

A further object is the provision, in a diaphragm of means to prevent the direct transmission of a sound of given periodicity to any locally responsive-portion of the diaphragm, to set up local vibrations there; in other words, it is an object to provlde a dia- I phragm which as a whole and in all portions is in efiect aperiodic.

electromagnetic structure and the improve ment of details of its manufacture and mounting.

lvly invention comprises the novel elective-- magnetic structure and mounting and. the novel diaphragm, aswell as the novel combination and arrangement thereof, as shown in the accompanying drawings, described in the specificatiomand particularly defined by the claims terminating the same; In the accompanying drawingsI have illustrated a preferred embodiment Of the prim ciples of my invention.

in place the disk 16 cannot A further object is the simplification of the .field is concentrated there. circuit is completed through a able union joint, shown as threaded annulus 4, secured Figure 1 is an axial section through the electromagnetic unit and its mounting.

Figure 2 1s a diagram of the electrical and magnetic circuits.

Figures 3, l, and 5 are axial sections illustlitillIlgSllCCGSSlVG steps in the manufacture of my diaphragm, and Figure 6 is a face View of the diaphragm. I

Figure 7 is a fragmentary elevation of a detail of the electrical connector block.

As the foundation for my device, I employ two magnetic cores 1 and 10, which are substantially alike, except that the core 10 is provided with an external threaded stem 11 by means of which it may recive a nut toclamp it to a rigid support 2. For economy thesecores are designed to be manufactured by an automatic screw machine, and for this purpose each is provided with a flange 14 at one end. At its opposite end a reduced neck 13 is formed, this fitting tightly within an aperture provided for this purpose in the respective casing halves or cups 3 and 30. If this neck does not fit tightly in its cup, or if the contact is poor between it and the cup, it can be held more tightly and brought into closer contact by swaging its outer end, as will be obvious. The windings 5 and can be retained on their respective cores 1 and 10 by securing a stifidielectric disk 15 thereon in contact with the flanges 14, and securing second dielectric disk 16 thereon at its opposite end, adjacent the inside of the cup. The disk '16 may be atight fit, to enable the coils to be wound, but when the core is secured possibly come ofi, inasmuch. as it lies against the inside of its i cup. The windings 5 and 50 are preferably so disposed, as shown diagrammatically in Figure 2, that the adjacent poles of the cores 1 and 1'0 are of opposite polarity.

The cups 3 and'3O are of magnetic material and form a double magnetic circuit centering at their respective cores 1 and 10, whereby the The magnetic type of adjustcomprising the to the casing 3, the flanged annulus 40 secured to the casing half 50, and. the flanged and threaded com nccting member ll. These members 1, 1O, and 4:1 are good magnetic conductors and thus the magnetic circuit is completed from the north pole 1 across the air gap to the south pole 10, thence through the members 30, s 0, 41, l, and 3 back to the north pole 1.

Supported between the two casing halves and between the two cores 1 and 10 is a diaphragm, which preferably is of a peculiar construction, as described hereafter. This is of magnetic material, but inasmuch'as the adjacent poles of the cores are of opposite polarity, and inasmuch as the magnetic circuit is completed through the casing members, the diaphragm itself will not become saturated but will respond sensitively to slight variations in the magnetic field caused by signals impressed upon the circuit through the windings 5 and 50. The diaphragm is so positioned, with respect to the windings, that it is attracted by one core simultaneously with its repulsion by the other core, to transmit the energ 1 thus produced to sounding medium. The cores 1 and 10 may be axially bored and a link 6 extends from a point of connection to the diaphragm to a connection to any suitable sounding medium, such as the cone 60. The cone 60 may be supported in any suitable or usual manner, and this serves as the actual sound reproducer. The opposite core is areferably apertured also to relieve the back side of the diaphragm from dampening air pressure variations.

The diaphragm employed consists of a highly tensioned central portion and a supporting annulus, which for the type of unit shown herein is preferably flexible. It is desirable that the inner portion be so highly stressed that its natural )eriod of vibration is above the range of audibility. To accomplish these two result-s, I may employ a composite diaphragm formed of two bulged disks 7, reversed to bring their convened sides together and then so held as to retain a central area under the stress caused by the flattening of the bulged disks.

Figure 3 shows the two separate, reversed disks. The next step is to connect the disks, and they are first connected at their centers by a weld, as indicated. at 70. The edges are then brought closer together until a central area 71 has been flattened. Thus held, the periphery of this central portion 71 is delined by welding, as indicated at 72, thus definitely and permanently retaining this central. portion 71 under a stress which can be made so great that its natural period is above the range of audibility. The stressing of the diaphragm may be secured in any suitable manner, and the construction shown is preferred in the present assembly because of the integral flexible mounting which can be formed at the same time. If the assembly with which the diaphragm is to be used does not require a flexible mounting, the diaphragm might be stressed in the manner disclosed in my application referred to above.

An annular portion of each disk remains free of the stressed central portion 71 and this, to a large extent, is unstressed. These marginal portions 73, when suitably held about their periphery, form a exible support for the stressed central portion 71. As shown in Figure 1, the annular marginal portions 73 are held in engagement with the peripheries of the casing members 3 and 30. By adjusting the annular coupling member 4C1 the casing members 3 and 30 and their cores 1 and 10 may be brought closer together or separated. The ideal condition for greatest volume is as close approach of the two cores as is possible without permitting actual contact of the diaphragm with either core when vibrating at its greatest amplitude.

A diaphragm which, as a whole, may have a natural period above the range of audimay yet have local areas or points which will vibrate in sympathy with tones within the range of audibility, and which will persist. Thus a persisting tone will mingle with and affect a following tone, and in order to prevent this interference and to render the diaphragm truly aperiodic within he range of audibility, I prefer so to form its central portion 71 as to break up or prevent ready communication between the point 76 of application of its force and a locally vibratory point. To this end, after the two halves have been welded together, as shown in Figure 4. I may crimp the two halves as indicated in Figures 5 and 6. The crimp has been shown in Figure 6 to take the form of a spiral T5, started at the central point 76 of thediaphragm and terminating at the welded periphery 72 of the central portion 71. This crimp being even more highly stressed than the general plane of the central portion 71, breaks up and prevents direct communication between any local area and the point of application of the force, and so delays communication between two such points that no interference results. The effect is of a diaphragm flexibly supported about its periphery and vibrating as a whole, without any periodicity of its own, in response to impulses of any periodicity within the range of audibility.

hat I claim as my invention is:

1. In a sound source, the combination with a sound impulse source. of a diaphragm operath ly within the influence of said source, and responsive to vibrations thereof, said diaphragm being stressed to give it a natural period above the limit of audibility.

In combination, a sound impulse source, a diaphragm connected to said source and responsive to vibrations thereof, said diaphragm being stressed to give it a natural period above the limit of audibility, and having means to eliminate direct communication between the area of application of the 'core principle energizing torces and locally vibratory areas; 7 3.111 combination, a diaphragm having a central area stressed to give it a natural period above the limit of audibility, and sup porting meansabout the periphery of said central area.

4;. In combination, vibratory diaphragm having a central area stressed to give it-a I natural period above the limit of audibility,

nu'lar. flexible supportsextending at each side or" the plane of the central area.

6. In a telephone-receiver, in combination, a casing comprising two halves, a central between said cores, and means for suppor ing said diaphragm from the casing and for adjusting the air. gap between said cores, to

maintain the diaphragm at all adjustments equally spaced from the two cores. y

7. In a telephone receiver, in combination,

a casing. comprising two halves, a vcentral core. projecting from each of said casing halves towards the other core toleave an air gap therebetween, means connecting said halves for relative axial adjustment to vary the air gap between the cores, a diaphragm equidistant between Said casinghalves and their cores, and means for maintaining the diaphragm always equidistant from the cores for any relative adjustment thereof;

8. In a telephone receiver, in combination, a casing comprising two halves, a central .core projecting. from, each half toward, the opposite core, and spaced therefrom to leave an air gap. means connecting said halvesfor relative axial adjustment to vary the airigap between the cores, and a diaphragm comprising a generally plane centralarea coaxial with and positioned betweengthe cores and.

a peripheral support engaged by the casing halves and yieldable axially thereof, whereby the central area oi the diaphragm isv maintained equidistant from the two cores. as the air gap therebetween is varied.

7 9. In a telephonereceiveiyin combination, a magnetic casing comprising two cup-like members having their rims spaced from each other, and magnetically connected, an axial core secured ineach half and projecting to- 'wards but spaced from the opposite core, a

coil associated with each casing half to maintain the adjacent ends of the cores of opposite polarity, and a diaphragm intersecting the strong magnetic field thus formed between the cores, and equidistantly spaced between said cores.

10. In a telephone receiver, in combination,

projecting from each of said casing halves towards the other' core to leave an air gap therebetween, a diaphragm positioned .formed to interrupt local vibrations tendina magnetic casing comprising two cup-like members having their rims spaced from each other, and magnetically connected, an axial core secured in each half and projecting to- Wards but spaced from the opposite core, a coil associated with each casing half to maintain the adjacent cndsnf the cores of opposite polarity, and a diaphragm intersecting the strong magnetic field thus formed between the cores, and equidistantly spaced between said cores, and means for adjusting the air gap between said cores, theidiaphragm be ng always maintained equidistant from the cores.

11 In a telephone receiver, in combination, 7 a casinghavmg a central'aperture, a shouldered core having its reduced portion received in said aperture, a flange on the end of said core, an apertured' disk supported on said coreand abutting against said flange. and a coil wound upon said core between the cas ing and said disk.

1 12. In a telephone receiver, in combination, a casing having a central aperture, an axially bored core having a reduced end tightlyreceivedin said aperture, a flange on said core opposite its reduced end, an apertured dielec- ,tricdiSk. supported on said core and abutting against said flange, a second dielectric disk on said core and abutting against said casing, and a coil wound on said core between said disks.

13. A, diaphragm comprising a central area and integral peripheral supports. said central area'being initially stressed to attain a natural period above the range of audibility, and said supports being normally'unstressed, and flexible in an axial direction.

14. A. diaphragm comprising a central area and integral peripheral supports, said central area being initially stressed to attain a natural period above the range of audibility, and said supports being normally unstressed, and flexible in an axial direction, means for attaching a link to said-central area, and said central area being disposedand toemanate from said link-attaching means. 15. A diaphragm comprising a central area and integral peripheral supporta'said central area being initially stressed to attain a natural'periodabove the rangeof audibility, and said supports beingnormally unstressed, and flexible in an axial direction, a sound impulse source oisposed adjacent the center of said'diaphragm to actuate the same,

and said central area being disposed and' formed tointerrupt localyibrations in the diaphragm tending to radiate from the region of application of the greatestapplied force.

disks placed'back to back and connected along 'a' circleoutward of their centers to. maintain each disk outward of such circles being left free and unconnected.

17. A diaphragm comprising two bulged disks placed back DO back and connected at their centers and along a circle outward therefrom, but inward of their peripheries, to maintain them str- 18. A diaphragm comprising two bulged disks placed back to back and connected at their centers and along a circle outward therefrom, but inward of their peripheries, to maintain them stressed, the area within said circle being deformed to interrupt local vibrations.

19. A diaphragm comprising a unitary central area initially stressed to have a natural period above the range of audibilit and peripheral supporting means therefor.

20. A diaphragm comprising a unitary central area initially stressed to have a natural period above the range of audibility, and peripheral supporting means therefor, said supporting means being normally unstressed and yieldable.

21. A diaphragm comprising a unitary central area initially stressed to have a natural period above the range of audibility, and peripheral supporting means therefor, comprising a pair of diverging flexible annuli integral with the central area but normally unstressed.

22. In combination, a diaphragm comprising a unitary central area initially stressed to have a natural period above the range of audibility, peripheral supporting means therefor comprising a pair of divergent flexible annuli extending about the central area, and a casing comprising two cup-like halves and means for adjusting said halves towards and from each other in an axial direction, said annuli being received each in its respective casing half to maintain the diaphragm in like relation to each half for any adjustment thereof.

23. The process of manufacturing a diaphragm which comprises securing together the centers of two bulged disks, placed back to back, stressing said disks by pressing them together to contact throughout a central area, and finally securing said disks about the periphery of said central area to maintain the same under stress.

24. The process of manufacturing a diaphragm which comprises pressing together two bulged disks, placed back to back, to contact throughout a central area, then per manently securing said disks about the pe riphery of said area, to maintain said area stressed to a degree where its natural period is above the range of audibility.

25. The process of manufacturing a diaphragm which comprises pressing together two bulged disks, placed back to back, to contact throughout a central area, then permanently securing said disks about the periphery of said area, to maintain said area stressed to a degree where its natural period is above the range of audibility, and finally deforming said central area to interrupt local vibrations.

26. The process of manufacturing a diaphragm which comprises pressing together two bulged disks, placed back to back, to contact throughout a central area, then permanently securing said disks about tie periphery of said area, to maintain said area stressed to a degree where its natural period is above the range of audibility, and finally crimping said central area spirally about the point of attachment to the same.

27. An electromagnetic structure comprising an apertured casing, a magnet core having a flanged end and having its opposite end adapted for securement in said aperture of the casing, a disk secured upon said core and retained by the flange thereon, a second disk secured upon the opposite end of said core, and elec 'ric windings about said core between said disks, and means upon the end of said core which is secured to the casing, and externally thereof, for supporting said elec tromagnetic structure.

28. In. a. telephone receiver, in combination, a casing, an electromagnet therein, and a diaphragm supported in said casing adjacent said magnet, and comprising a supporting ring of magnetic material, and a stressed diaphragm supported in said ring and eX- tending over said magnet.

29. A diaphragm comprising an outer supporting annulus and a central portion stressed to give it a natural period above the range of audibility.

30. A diaphragm comprising a central portion having a sharply defined periphery, and stressed to give it a natural period above the range of audibility, and a surrounding supporting portion.

31. A diaphragm adapted to vibrate in accordance with the complex waves of sound vibrations comprising a central portion adapted to vibrate as a unit, and so stressed that its resultant period of vibration is substantially above the limits of audition, and 1 a resilient peripheral portion.

Signed at Seattle, King county, VVashington, this 29th day of September 1926.

GARRISON BABCOCK.

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