Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3531745 A
Publication typeGrant
Publication dateSep 29, 1970
Filing dateOct 22, 1969
Priority dateOct 22, 1969
Publication numberUS 3531745 A, US 3531745A, US-A-3531745, US3531745 A, US3531745A
InventorsTibbetts George C
Original AssigneeTibbetts Industries
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Magnetic translating device with armature flux adjustment means
US 3531745 A
Images(1)
Previous page
Next page
Description  (OCR text may contain errors)

Sept. 29,1970 s. c. TIBBETTS 3,531,745

MAGNETIC TRANSLATING DEVICE WITH ARMATURE FLUX ADJUSTMENT MEANS Original Filed Aug. 28, 1957 United States Patent ()ffice 3,531,745 Patented Sept. 29, 1970 3,531,745 MAGNETIC TRANSLATING DEVICE WITH ARMATURE FLUX ADJUSTMENT MEANS George C. Tibbetts, Camden, Maine, assignor to Tibbetts Industries, Inc., Camden, Maine, a corporation of Maine Continuation of application Ser. No. 680,753, Aug. 28, 1957. This application Oct. 22, 1969, Ser. No. 868,495 Int. Cl. H01f 7/08 U.S. Cl. 335-231 23 Claims ABSTRACT OF THE DISCLOSURE A magnetic translator of the balanced armature type having magnetic material of opposite polarity on opposite sides of the armature for supplying magnetic flux to it. The armature has a fixed end and a free end, and is provided with adjustment means at the fixed end for varying the reluctance between the armature fixed end and the magnetic material, thereby to adjust the steady magnetic flux passing lengthwise through the armature.

Cross-reference to related application This is a continuation of application Ser. No. 680,753, filed Aug. 28, 1957.

Background of the invention The present invention of concerned with magnetic transducers and other magnetic translating devices having a movable armature, depending for operation on variable gaps and variable magnetic fluxes, and thereby capable of translating mechanical to electrical energy or vice versa, and particularly with means of obtaining substantial, yet delicate and stable adjustments of the magnetic state of the movable armature in such a translator.

High efficiency magnetic translators of the moving armature type generally employ a so-called balanced armature construction, in which the armature is intended to carry none of the steady polarizing flux except in the regions of the gaps, and to carry only signal flux in the other regions of the armature. It is highly desirable that the armature carry as little steady flux as possible along its magnetic signal axis or axes, in regions outside the gaps, because its cross-section must be small in order that the armature may flex with sufficient mechanical compliance and possess sufiiciently low effective moving mass. Furthermore, in order to present sufficiently low reluctance to signal flux, the armature will usually be fabricated from one of the higher permeability materials, which generally have relatively low saturation inductions. The net result of these factors is that the armature is not well adapted to carry steady flux along a magnetic signal axis, because of the ready approach to saturation and the consequent severe loss of incremental permeability to signal flux. Although it is not intended that the armature carry steady flux along a magnetic signal axis in the balanced armature construction, in practice the armature generally has been required to do so to a considerable degree because of the difficulty heretofore in obtaining a delicate and stable adjustment of the amount of such steady flux. The armature enters both fixed and variable gaps at its extremities, and in general the ideal is to have the steady magnetic potentials equal at these extremities so that the armature will not be forced to carry steady flux between them. Any residual mechanical misalignment of the armature in the gaps, which remains after fabrication of the unit, will destroy the equality of the magnetic potentials at the extremities of the armature, and will cause steady tlux to flow between them, when the magnets of the transducer are magnetized. This undesirable effect is further enhanced by the magnetic instability factor of a moving armature magnetic transducer, in which the magnetic forces on the armature due to unbalance cause further increase of mechanical misalignment and hence of magnetic unbalance, until a stable but magnified misalignment and unbalance is reached. The increasing miniaturization of transducer assemblies requires in general that the dimensions of all parts of the transducer be reduced, including the cross-section of the armature. As the size of certain types of transducer assemblies is reduced, e.g., microphones, the sensitivity also tends to reduce. One of the important means of maintaining sufficiently high sensitivity of such magnetic transducers is to employ a magnetic instability factor as high as practicable. Hence the problem of obtaining a sufficiently low steady flux density in the armature of moving armature magnetic transducers is greatly accentuated by the process of miniaturization.

The principal object of my invention is to provide means in a balanced armature magnetic translator for adjusting accurately and permanently the magnetic state of the armature and hence of obtaining as close an approximation to magnetic balance as may be desired.

It is often desirable to be able to perform an adjustment of the type described above upon a complete transducer assembly in which the transducer unit is generally inaccessible from the exterior of the assembly. For example, the introduction of a transducer unit into an assembly may result in an appreciable magnetic unbalance of the unit if the assembly contains of necessity other magnetic components in proximity to the unit. As another example, in the application of transducer assemblies of the sound generating type, it is sometimes necessary that the electrical coil of the transducer carry a direct current bias, and in this case the transducer units must of course be adjusted for a magnetic balance that depends upon the amount of bias current. If a large number of design-center bias currents are required on demand, it may be desirable in the interest of simplicity of production to fabricate transducer units balanced for an average value of bias current, and subsequently to perform on essentially complete transducer assemblies a further balancing adjustment for the particular designcenter bias current required.

Hence as further object of my invention is to provide delicate and stable adjustment of the magnetic state of the moving armature of a magnetic transducer, in such form as may be readily used by manipulation from the exterior of a generally enclosed complete transducer assembly.

Summary of the invention These objects are accomplished in my invention by providing a readily adjustable flux of suitable polarity to the armature in the vicinity of a gap. Flux supplied in this manner to the armature divides into various paths in a quantitative way depending upon the reluctances of the various magnetic circuits involved, but in any case if the proper amount of flux can be delivered, the flux through the reed along its magnetic signal axis extending beyond the gap may be brought to zero or to a definite value and polarity, the arbitrary flux initially present having been bucked out by a portion of the flux supplied externally to the gap region.

The invention may be realized in a number of different ways. In one aspect, flux may be supplied to the armature in the vicinity of a gap by means of a magnetically permeable extension in and/ or extending beyond the gap region. In the second aspect, flux may be adjustably supplied to such an extension by various means. Preferably however, in this second aspect of the invention, the extension itself serves as the adjusting means and is 3 plastically and permanently deformed, as by bending, in order to vary the reluctances of the various paths from the extension to other magnetic portions of the unit at differing magnetic potentials, and hence to vary the net rflux to or from the extension.

It is evident that the magnetically permeable extension need not be integral with the armature, but may be attached to the armature in a variety of ways, or placed in magnetic proximity to the armature in or adjacent to a gap region. Furthermore, an extension need not extend in a gap region, but instead may extend from the armature over a region exterior, but adjacent, to a gap region. Again, it is evident that the extensions need not be bent, but may be made to present adjustable reluctances to the pole pieces or other soft magnetic portions of the unit by additional means, such as the interposition of movable and magnetically permeable wedges or blocks, or by the application of a controllable amount of an interposed coating or filler pigmented with ferromagnetic particles, or by other means accomplishing the same objective. Alternatively, the magnetically permeable extension may be a portion of, or in fixed relation to, a pole piece or other magnetic part of the unit. In this case the extension may be made to present an adjustable reluctance to the armature in the vicinity of a gap and hence to deliver an adjustable flux to this region, for example by bending the extension toward or from the armature.

In one aspect the invention involves a magnetic translating device comprising an armature, a support for one end of the armature with the other end free to vibrate transversely of a predetermined plane, magnetic means for supplying magnetic flux to the armature including pieces of magnetic material having pole faces on opposite sides of said plane respectively and presenting said faces to the vibratory end of the armature, said means having surfaces of soft magnetic material of opposite magnetic polarity and variable means for varying the reluctances between said armature and said surfaces, the variable means comprising a magnetic flux conductor magnetically associated with the one end and extending along the plane. The reluctance variations may be accomplished, for example, by varying the gaps between the conductor and the surfaces, whereby auxiliary flux may be adjustably supplied to vary the state of magnetic flux in the arma ture. While the magnetic flux conductor may be a separate piece of material, either touching the armature or juxtaposed thereto, preferably it is an integral part of the armature.

In another aspect the invention involves a device comprising an armature having a fixed portion and a portion vibrating transversely of a plane, means for supplying magnetic flux to the armature including a piece of magnetic material having a pole face on one side of the armature and presenting said face to said vibrating portion of the armature, said means also including a piece of soft magnetic material disposed on said same side of the armature and presenting a pole face to said fixed portion of the armature across a gap, and a magnetic flux conductor interposed between the armature and said second piece in the vicinity of said second face, the conductor being movable transversely of said plane to vary the state of magnetic flux in the armature.

In another aspect the invention involves a translating device comprising an armature having a fixed portion and a portion vibrating transversely of a plane, means for supplying magnetic flux to the armature including a piece of soft magnetic material disposed on one side of the armature and presenting a pole face to the fixed portion of the armature across a gap, and a magnetic flux conductor extending from the armature in the vicinity of the gap and movable transversely of said plane toward and from the aforesaid piece of soft magnetic material to vary the state of magnetic flux in the armature.

In a more specific aspect the device includes two structures of soft magnetic material of opposite magnetic polarity, the structures being disposed on opposite sides of the armature respectively and presenting pole faces to the armature across air gaps or other gaps of relatively high magnetic reluctance, the magnetic flux conductor extending from the armature in the vicinity of the gaps.

In a still more specific aspect of the invention the translating device comprises an armature, means for supporting one end of the armature with the other end free to vibrate transversely of a predetermined plane, magnets extending lengthwise of the armature on the opposite sides thereof which are intersected by the aforesaid plane, the poles of the magnets being directed transversely of the plane in corresponding directions, and bridges of magnetic material substantially bridging the space between the poles of the magnets on opposite sides of the aforesaid plane respectively, the bridges presenting pole faces of opposite polarity to the aforesaid vibratory end, the armature having a tab projecting from said one end along said plane and extending between said bridges, the tab being bendable transversely of the plane toward either of the bridges. The armature is preferably formed of sheet material with the aforesaid tab projecting from one edge thereof.

Description of the drawing Description of the preferred embodiments.

FIG. FIG. FIG. FIG. FIG. FIG. FIG.

The particular embodiment of the invention shown in FIGS. 1 to 5 comprises a coil 1, which may for example be of the type disclosed and claimed in the copending application of Raymond W. Tibbetts, now Pat. No. 2,988,804, issued June 20, 1961, an armature 2 extending through the opening in the coil, magnets 6 and 7 extending lengthwise of the armature on the opposite sides of the coil which are intersected by the plane of the armature, the poles of the magnets being directed transversely of the plane in corresponding directions as indicated by the letters N and S in FIGS. 2 and 4, and thin sheets 8 and 9 of magnetic material substantially bridging the space between the poles of the magnets on opposite sides of the aforesaid plane respectively. While the coil may be mounted on one sheet only, as by adhesive, as illustrated the sheets are shaped to fit the coil snugly and hold it in position. At each end of the sheets 8 and 9 converge toward the armature both laterally and longitudinally to central portions which parallel the armature in close juxtaposition thereto. At the right end (FIGS. 1 and 3) a nonmagnetic spacer 11 is interposed between each sheet and the armtaure and the parts are secured together by means of a screw 12 extending through opening 13. At the left end the armature is free to vibrate between the pole faces 14 and 16 (FIG. 2). To transfer vibration to or from the armature a yoke 17 straddles the armature and pinches it snugly therebetween, the yoke extending outwardly through an opening 18 in the sheet 8. At its anchored end the armature has flexible tabs 19 and 20 which may be bent toward one or the other of the sheets 8 and 9. The ends of the coil may be connected to insulated terminals 21. The sheets 8 and 9 may be secured to the magnets 6 and 7 or to the coil or to both by means of a suitable cement such as fluid epoxy resin with an amine type hardener.

The modification shown in FIGS. 6 and 7 is similar to that shown in FIGS. 1 to 5 and corresponding parts are correspondingly designated. However, instead of the armature being T-shaped it is E-shaped, comprising a central portion 22 corresponding to the part 2 of the first embodiment, and end portions 23 and side portions 24. Instead of a single magnet on each side there are two magnets 26 and 27 on opposite sides of each of the portions 24 of the armature. As in the first embodiment the poles of the magnets are directed transversely of the plane of the armature in corresponding directions as indicated by the letters N and S in FIG. 7. Tabs 29 and 30, corresponding to tabs 19 and in the first embodiment, are located on the ends of the portions 24 of the E-shaped armature, the magnets 26 and 27 being shortened to provide a space between the sheets 8 and 9 so that each tab may be bent toward either sheet.

The modification shown in FIGS. 8 and 9 is similar to that shown in FIGS. 1 to 5 and corresponding parts are correspondingly designated. However, instead of the armature 31 being T-shaped, it is straight, and the flexible adjustment tabs 39 and 40, corresponding to tabs 19' and 20, are provided on a separate leaf 32 resting on the end of the armature instead of being formed as an integral part thereof. Both leaf 32 and armature 31 have an opening 33 therethrough, corresponding to opening 13, to receive screw 12.

In the course of adjustment of the unit of FIGS. 1 to 5, subsequent to the assembly of the unit and the magnetization of the magnets 6 and 7, either or both of the tabs 19 and 20 are bent so as to approach more closely the adjacent surfaces of either sheet 8 or 9 as the need may be in order to adjust in the desired direction the steady flux through the armature along its magnetic signal axis, i.e., through the coil 1. By changing in this way the reluctances of the paths from the tabs 19 and 20* to the sheets 8 and 9, which are at different and opposite magnetic potentials from the tabs 19 and 20, the net flux to the tabs 19 and 20 may be adjusted, and thereby the steady flux carried by the armature along its magnetic signal axis may be brought to zero as closely as may be desired, or may be brought to a predetermined value and polarity as may be desired. The adjustment can be made readily and quickly, yet with great delicacy, and has proven to be extremely stable and permanent.

An important feature of the present invention is that the tabs 19 and 20 work opposite to and have their primary magnetic flux collecting paths to the soft magnetic sheets 8 and 9. Thus the tabs may be applied to a parallel magnetic circuit type unit such as shown in FIGS. 1 to 5. Moreover, either of the tabs 19 and 20 can be made to collect flux of either sign depending upon the direction in which it is bent. When a tab is bent it increases the magnetic shunting effect on one side while it decreases the effect on the other side. In the modification shown in FIGS. '6 and 7 either of the tabs 29 and 30, when bent, decreases the shunting effect on one magnet while simultaneously increasing the shunting effect on the other magnet of the magnet pair 26 and 27, with the result that the flux supplying capability of the magnet pair is not appreciably reduced by the adjustment. In the modification shown'in FIGS. 8 and 9, bending of the tabs 39 and 40 produces the same reluctance adjusting effect as does bending the tabs 19 and 20 in the unit of FIGS. 1 to 5.

I claim:

1. A magnetic translating device comprising an armature, a support for one end of the armature with the other end free to vibrate transversely of a predetermined plane, magnetic means for supplying magnetic flux to the armature including pieces of magnetic material having pole faces on opposite sides of said plane respectively and presenting said faces to the vibratory end of the armature, said means having surfaces of soft magnetic material of opposite magnetic polarity, and variable means for varying the reluctances between said armature and said surfaces, said variable means comprising a magnetic flux conductor magnetically associated with said one end and extending along said plane.

2. A magnetic translating device comprising an el0n- Cit gate armature, means for supporting one end of the armature with the other end free to vibrate transversely of a predetermined plane, magnets extending lengthwise of the armature on the opposite sides thereof which are intersected by said plane, the poles of the magnets being directed transversely of the plane in corresponding directions, and bridges of magnetic material substantially bridging the space between the poles of the magnets on opposite sides of said plane respectively, said bridges presenting pole faces of opposite polarity to said vibratory end, said armature having a tab projecting from said one end along said plane and extending between said bridges, the tab being bendable transversely of the plane toward either of said bridges.

3. A magnetic translating device comprising an elongate armature of sheet material, means for supporting one end of the armature with the other end free to vibrate transversely of the plane of the sheet material, magnets extending lengthwise of the armature on the opposite sides thereof which are intersected by said plane, the poles of the magnets being directed transversely of the plane in corresponding directions, and bridges of magnetic material substantially bridging the space between the poles of the magnets on opposite sides of said plane respectively, said bridges presenting pole faces of opposite polarity to the opposite sides of said vibratory end, said armature having a tab associated with said one end and projecting from an edge thereof along said plane, the tab being bendable transversely of the plane toward either of said bridges.

4. A magnetic translating device comprising an elongate armature, means for supporting one end of the armature with the other end free to vibrate transversely of a predetermined plane, magnets extending lengthwise of the armature on the opposite sides thereof which are intersected by said plane, the poles of the magnets being directed transversely of the plane in corresponding directions, and bridges of magnetic material substantially bridging the space between the poles of the magnets on opposite sides of said plane respectively, said bridges presenting pole faces of opposite polarity to each of said ends, said first end of the armature having a tab projecting therefrom along said plane and extending between said bridges, the tab being bendable transversely of the plane toward either of said bridges.

5. A magnetic translating device comprising an elongate armature of sheet material, means for supporting one end of the armature with the other end free to vibrate transversely of the plane of the sheet material, magnets extending lengthwise of the armature on the opposite sides thereof which are intersected by said plane, the poles of the magnets being directed transversely of the plane in corresponding directions, and bridges of magnetic material substantially bridging the space between the poles of the magnets on opposite sides of said plane respectively, said bridges presenting pole faces of opposite polarity to each of said ends, said first end of the armature having a tab projecting from an edge thereof along said plane and extending between said bridges, the tab being bendable transversely of the plane toward either of said bridges.

6. A magnetic translating device comprising an E- shaped sheet of magnetic material, the middle arm forming an armature which is free to vibrate transversely of the plane of the sheet material, magnets extending lengthwise of the armature on the opposite sides thereof and on opposite sides of each of the end arms of said E-shaped sheet, the poles of the magnets being directed transversely of the plane in corresponding directions, and bridges of magnetic material substantially bridging the space between the poles of the magnets on opposite sides of said plane respectively, said bridges presenting pole faces of opposite polarity to the free end of the armature, the outer end of one of the end arms of the E-shaped sheet projecting along said plane beyond the corresponding end of the magnets between said bridges and being bendable transversely of said plane toward either of said bridges, a part of said one end arm being fixed.

7. A transducer comprising an electromagnetic coil having an opening therethrough, an armature extending through said opening with a part projecting from each end of the coil, means for supporting one part, the other part being free to vibrate transversely of a plane containing the axis of the coil, magnets extending lengthwise of the armature on the opposite sides of the coil which are intersected by said plane, the poles of the magnets being directed transversely of the plane in corresponding directions, and bridges of magnetic material substantially bridging the space between the poles of the magnets on opposite sides of said plane respectively, said bridges and magnets substantially enclosing the coil, and said bridges presenting pole faces of opposite polarity to said other part of the armature, said armature having a tab projecting from said one part along said plane and extending between said bridges, the tab being bendable transversely of the plane toward either of said bridges.

8. A magnetic translating device comprising an armature, a support for one end of the armature with the other end free to vibrate transversely of a predetermined plane, magnetic means for supplying magnetic flux to the armature including pieces of magnetic material having pole faces on opposite sides of said plane respectively and presenting said faces to the vibratory end of the armature, said means having surfaces of soft magnetic material of opposite magnetic polarity, portions of the armature facing toward said surfaces to receive auxiliary magnetic flux from said means through said surfaces, and variable means for varying the reluctances between said portions and said surfaces, said variable means comprising a magnetic flux conductor magnetically associated with said one end and extending along said plane.

9. A magnetic translating device comprising an armature having a fixed end and an end vibrating transversely of a plane, means for supplying magnetic flux to the armature including two structures of soft magnetic material of opposite magnetic polarity disposed on opposite sides of the armature respectively, and a magnetic flux conductor associated with said fixed end and extending from the armature along said plane between said structures and movable toward either of the structures to vary the state of magnetic flux in the armature.

10. A magnetic translating device comprising an armature having a fixed end and an end vibrating transversely of a plane, means for supplying magnetic flux to the armature including pole faces presented to the armature on opposite sides thereof respectively, said means also including two portions of soft magnetic material of opposite magnetic polarity, and a magnetic flux conductor associated with said fixed end and extending from the armature along said plane in the vicinity of said faces and movable toward either of said portions to vary the state of magnetic flux in the armature.

11. A magnetic translating device comprising an armature having a fixed portion and a portion vibrating transversely of a plane, means for supplying magnetic flux to the armature including a piece of magnetic material having a pole face on one side of the armature and presenting said face to said vibrating portion of the armature, said means including also a piece of soft magnetic material disposed on said same side of the armature and presenting a pole face to said fixed portion of the armature across a gap, and a magnetic flux conductor interposed between the armature and said second piece in the vicinity of said second face, the conductor being movable transversely of said plane to vary the state of magnetic flux in the armature.

12. A magnetic translating device comprising an armature having a fixed portion and a portion vibrating transversely of a plane, means for supplying magnetic flux to the armature including a piece of soft magnetic material disposed on one side of the armature and presenting a pole face to the fixed portion of the armature across a gap, and a magnetic flux conductor interposed between the armature and piece in the vicinity of said gap, the conductor being movable transversely of said plane to vary the state of magnetic flux in the armature.

13. A magnetic translating device comprising an armature having a fixed portion and a portion vibrating transversely of a plane, means for supplying magnetic flux to the armature including a piece of soft magnetic material disposed on one side of the armature and presenting a pole face to the fixed portion of the armature across a gap, and a magnetic flux conductor extending from the armature in the vicinity of said gap and movable transversely of said plane toward and from said piece to vary the state of magnetic flux in the armature.

14. An electromagnetic transducer comprising a magnet, a pole piece fiux-conductively engaging each pole of the magnet, said pole pieces extending laterally of the magnet to form a nonmagnetic gap therebetween, an elongated, flux-conductive, elastic armature, means clamping one end of said armature in nonmagnetic, spaced relationship to the pole pieces in fixed position in said gap so that the other end of said armature may vibrate in another portion of said gap, there being a bending line between the clamp end and the vibratable end of the armature, and means for varying the reluctance between the tween the clamp end and the vibratable end of the armature.

15. The electromagnetic transducer of claim 14 wherein the reluctance varying means is a T-shaped armature with the clamped portion between the arms of the T which project laterally on both sides into the gap.

16. An electromagnetic transducer comprising a magnet, a pole piece fiux-conductively engaging each pole of the magnet, said pole pieces extending laterally of the magnet to form a nonmagnetic gap therebetween, an elongated, flux-conductive, elastic armature, means clamping one end of saidarmature in nonmagnetic, spaced relationship to the pole pieces in substantially fixed position in said gap so that the other end of said armature may vibrate in another portion of said gap, and means for varying the reluctances between the armature and each of the pole pieces in the portion of the gap at said one end of the armature.

17. An electromagnetic transducer as in claim 16 wherein the reluctance varying means is a wing integrally formed with the armature at said one end and which wing extends laterally thereof into the gap.

18. An electromagnetic transducer as in claim 16 wherein said armature is T-shaped and said one end is the portion between the arms of the T, said reluctance varying means comprising the arms of the T which project laterally on both sides into the gap.

19. An electromagnetic transducer comprising a magnet, a pole piece flux-conductively engaging each pole of the magnet, said pole pieces extending laterally of the magnet to form a nonmagnetic gap therebetween, an elongated, flux-conductive armature positioned in said gap, a fluxconductive leaf flux-conductively resting on one end of said armature and projecting laterally into the adjacent portion of the gap, a spacer of low flux conductivity positioned between said leaf and the adjacent pole piece, and a spacer of like material positioned between the armature and the other pole piece, said spacers, flux-conductive leaf, and armature being in a stack clamped between said pole pieces in a fixed relationship so that the other end of the armature may vibrate in another portion of said gap.

20. The electromagnetic transducer of claim 19 wherein the material of the leaf is not only flux-conductive but readily bendable.

21. A magnetic translating device comprising an elongate armature, means for supporting one end of the armature with the other end free to vibrate transversely of a predetermined plane, magnets extending lengthwise of the armature on the opposite sides thereof which are intersected by said plane, the poles of the magnets being directed transversely of the plane in corresponding directions, and pole pieces of magnetic material having portions extending between the poles of the magnets on opposite sides of said plane respectively, said pole pieces presenting pole faces of opposite polarity to said vibratory end, said armature having a tab projecting from said one end along said plane and extending between said pole pieces, the tab being bendable transversely of the plane toward either of said pole pieces.

22. A magnetic translating device comprising a elongate armature, a support for one part of the armature with another part free to vibrate, a magnetically polarized structure presenting a pair of pole faces to the vibratable part of said armature, and means displaceable in either direction from a magnetically neutral position in a magnetic field provided by said structure, said means conducting flux to or from said one part of the armature and thereby permanently adjusting the magnetic flux passing lengthwise through said armature.

23. A magnetic translating device comprising a pair of pole pieces with a space therebetween, means for creating a magnetic field between said pole pieces, an armature between said pole pieces, and means for permanently adjusting the reluctances between a portion of the armature and each of the pole pieces, said adjusting means being displaceable in one direction to simultaneously decrease reluctance with respect to one pole piece and increase reluctance with respect to the other pole piece, and displaceable in the opposite direction to simultaneously produce the opposite reluctance adjustments.

References Cited UNITED STATES PATENTS 20 GEORGE HARRIS, Primary Examiner US. Cl. X.R. 179114

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2443784 *May 17, 1943Jun 22, 1948Barber Coleman CompanyRelay
US2491140 *Apr 11, 1945Dec 13, 1949Barber Colman CoArmature assembly
US2511114 *Jun 6, 1947Jun 13, 1950Bell Telephone Labor IncPolarized electromagnet
US2912522 *Jun 14, 1954Nov 10, 1959Ind Res Products IncElectro-mechanical transducing device
US2912523 *Oct 26, 1955Nov 10, 1959Ind Res Products IncElectro-acoustic transducer
CH217613A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4410769 *Dec 9, 1981Oct 18, 1983Tibbetts Industries, Inc.Transducer with adjustable armature yoke and method of adjustment
US4518831 *Nov 4, 1983May 21, 1985Tibbetts Industries, Inc.Transducer with translationally adjustable armature
US4922217 *Jun 17, 1988May 1, 1990Hsc Controls, Inc.Torque motor with magnet armature
US6075870 *Dec 1, 1997Jun 13, 2000Microtronic B.V.Electroacoustic transducer with improved shock resistance
US6658134Aug 16, 1999Dec 2, 2003Sonionmicrotronic Nederland B.V.Shock improvement for an electroacoustic transducer
US7065224Sep 28, 2001Jun 20, 2006Sonionmicrotronic Nederland B.V.Microphone for a hearing aid or listening device with improved internal damping and foreign material protection
US7072482Sep 6, 2002Jul 4, 2006Sonion Nederland B.V.Microphone with improved sound inlet port
US7236609 *Oct 6, 2000Jun 26, 2007Knowles Electronics, Llc.Electro-acoustic transducer with resistance to shock-waves
US7995789Jun 21, 2007Aug 9, 2011Knowles Electronics, LlcElectroacoustic transducer with resistance to shock-waves
EP0094992A1 *May 21, 1982Nov 30, 1983Knowles Electronics CompanyElectroacoustic transducers
Classifications
U.S. Classification335/231
International ClassificationH02K33/00, H01F7/14, H04R11/00, H01F7/08, H02K33/06
Cooperative ClassificationH02K33/06, H01F7/14, H04R11/00
European ClassificationH04R11/00, H01F7/14, H02K33/06