WO2013057726A2

WO2013057726A2 - Mirror symmetric magnetic circuits transducer and parts

Info

Publication number: WO2013057726A2
Application number: PCT/IB2012/055785
Authority: WO
Inventors: Praveen Vallabhaneni
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-10-21
Filing date: 2012-10-21
Publication date: 2013-04-25
Anticipated expiration: 2014-04-21
Also published as: WO2013057726A3

Abstract

Substantially symmetric magnetic circuits and coil-diaphragm connectors for electrodynamic transducer where the coil(s) is/are connected to the diaphragm via surface gap(s) in the magnetic circuit part(s) enclosing the coil or enclosed by the coil or both thereby minimizing non-linear coil force asymmetries and improving coil centering and excursion stability.

Description

MIRROR SYMMETRIC MAGNETIC CIRCUITS TRANSDUCER AND PARTS

BACKGROUND

Technical Field

The present application relates to mirror symmetric magnetic field circuits where the circuit is made of substantially similar (preferably mirror symmetric) magnetic flux circuit path halves and coil-diaphragm connections through slots/openings in magnetic circuit poles defining the voice coil magnetic gap(s).

Description of related art:

This listing is only intended as illustrative of related art and specifically is not intended as a representation that no closer related art exists to the claimed invention. Although the listed related art generally illustrate what are believed to be closest slotted pole transducer designs, they suffer from structural and design weaknesses that hinder reliability, performance and sound quality.

In US5081684, the magnetic structure does not consist of symmetric flux return path halves and hence does not reduce coil force asymmetry based distortions.

In US5883967, the transducer is limited to the diaphragm itself incorporating slots and ribs in its relatively outer region which hinders excursive stability of the diaphragm, makes diaphragm and transducer fabrication complex and less reliable.

In US20110044491A1, the magnetic structure is limited to inner magnet type structuring with two axially charged magnets coupled to a single drive plate and the ribbed coil-diaphragm connector is limited to the shown design which is only formed as a whole and is bulky, thereby increasing costs and decreasing performance of the transducer.

In US6836551, the magnetic structure does not consist of symmetric halves and the bent strip forming the ribbed connector lacks fully covered inner and outer sections thereby compromising the integrity of the connection with the apex of the diaphragm and also with the voice coil windings, also because of the lack of cully formed inner/outer sections, thermal conductivity is also hindered thereby increasing the risk of thermal compression and voice coil degradation.

Statement of the invention :

Substantially mirror symmetric flux circuits help provide substantially symmetric fields to the coil(s) placed in the magnetic gap(s) thereby producing substantially - same thrust forces during both directions of excursion, same structural and material environments during both directions of excursions, thereby drastically reducing non-linear distortions due to coil force asymmetry, coil inductance differences, heat dissipation differences and air pressure differences between to and fro excursions of the voice coil(s), hence reducing harshness of sound, especially at louder volumes and also efficiently utilizing magnetic flux available from the magnet(s), which may be permanent or electromagnetic or a hybrid of both.

Summary:

Improvements in mirror symmetric magnetic circuits and coil-diaphragm connections for transducer invention in Indian patent application 2767/CHE/2010. The invention has the virtue of the voice coil(s) being connected to the diaphragm(s) via slot(s) enclosing the coil or enclosed by the coil or both. Mirror symmetric structuring of the magnetic circuit helps reduce coil force asymmetry between the excursion cycles. Furthermore the improvements in the original invention also extend to the structuring of the coil-diaphragm connection, also using a concentric ribbed connector(s) which can be fabricated at once or as assembly of one or more parts geometrically bent and assembled to form the inner, outer and rib section(s) of the coil-diaphragm connector. The invention and the improvements allow for high reduction in voice coil rocking during high excursion by the possibility of the suspension (spider etc) in the same plane of the voice coil or by providing better structural support by virtue of placement, thereby allowing for tighter coil air gaps hence increasing magnetic efficiency. The supporting frame / basket of the transducers are not concentrated upon in order to avoid visual confusion, the same is not to be construed as a shortcoming since a supporting frame/basket can be easily designed by anyone skilled in the art, having the benefit of this disclosure.

Brief description of drawings

The invention will now be described with reference to accompanying drawings in which,

Figure - 1 shows the basic blown up structuring of mirror symmetric magnetic circuit transducer iteration.

Figure - 2 shows the mirror symmetry X axis and the four possible axes Y1, Y2, Y3 and Y4 of the fundamental rotational construction of the magnetic circuit prior to incorporation of desired slots in the pole(s).

Figure - 3 shows how the fundamental magnetic circuit paths can be split into multiple parts for ease of design and manufacturing.

Figure - 4 shows side how the basic magnetic circuit paths can be shaped without changing the circuit.

Figure - 5 shows a basic mirror symmetry magnetic circuit possible using two sets of radially polarized magnets.

Figure - 6 shows a basic mirror symmetry magnetic circuit with two sets of axially polarized magnets with the central pole plates separated by a separator.

Figure - 7 shows the basic mirror symmetry magnetic circuit with two sets of axially polarized magnets with the central pole plates separated by a separator and with isolated return paths.

Figure - 8 shows a basic mirror symmetric magnetic circuit for multiple voice coils and isolated pole plates and return paths using two axially polarized magnet sets

Figure - 9 shows a cut section view of a mirror symmetric transducer structuring with diaphragm and spider suspension coupled to the coil-diaphragm connector and the motor concealed within the diaphragm and dust cap.

Figure - 10 shows a cut section view of a mirror symmetric magnetic circuit transducer structuring with a phase plug coupled to the motor structure itself.

Figure - 11 shows a mirror symmetric magnetic circuit transducer with magnets inside the coil, for headphones and compact electronic devices.

Figure - 12 shows a mirror symmetric magnetic circuit transducer with magnets outside the coil, for headphones and compact electronic devices.

Figure - 13 shows a mirror symmetric magnetic circuit with extended return paths to allow for higher coil excursion, with diaphragm placed coaxial to the magnetic structure and connected to the coil-diaphragm connector separately.

Figure - 14 shows the mirror symmetric construction of the transducer with the mirror symmetric magnetic circuit using axially magnetized magnets and mirror symmetry structuring of multiple diaphragms and suspensions.

Figure - 15 shows the mirror symmetric construction of the transducer with the mirror symmetric magnetic circuit using radially magnetized magnets and mirror symmetric structuring of multiple diaphragms and suspensions.

Figure - 16 shows a mirror symmetry magnetic circuit transducer type enclosing the diaphragm and having suspension material coupled between the coil-diaphragm connector surface and the magnetic structure surface.

Figure - 17 shows a underhung coil type structuring of the mirror symmetric magnetic circuit using multiple radially magnetized magnets to allow for the coil to commutate over the magnets over the excursion cycle.

Figure - 18 and subdivisions show how the coil-diaphragm connector can be structured in many different ways and fabricated at once or assembled out of single or multiple parts.

Figure - 19 shows multiple structuring of the coil-diaphragm connector ribs and voice coil structure(s).

Detailed Description

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.

Definitions:

Certain terms are defined for the purpose of this invention.

Fundamental Magnetic Circuit:

When a magnetic field producing part such as a permanent magnet, field coil etc, is incorporated into a housing or mounted to other part(s), which may be magnetically conducting in nature (eg: ferromagnetic materials) so as to allow the flow of magnetic flux from one pole of the magnet to the other pole and over any gap(s) in the path of the magnetic flux, it is be called a Magnetic Circuit. Fundamental magnetic circuits are magnetic circuits which can be depicted in their basic state prior to axial rotational construction and slotting/opening of one or more poles for the coil-diaphragm connection rib(s), which are easy to design by anyone skilled in the art, having the benefit of this disclosure.

Substantially Mirror Symmetric Magnetic Circuit:

When the magnetic circuit construction is such that it consists of a central symmetric axis defining two geometrically opposite halves as in a mirror reflection, it may be said to be a Mirror Symmetric Magnetic Circuit. During actual practice some of the mirror symmetry may be sacrificed during mechanical fabrication of magnetic circuit parts due to various reasons whilst retaining the general symmetric and/or oppositional arrangement of the magnetic circuit halves, such deviations from intended mirror symmetry are to be understood from a practical point of view and not as deviating from the theory or beyond the scope of the claims of this application incorporating the term 'Substantially Mirror Symmetric' or 'Substantially Symmetric'.

Magnetic space/gap:

It is the space/gap between two magnetic pole faces constituting magnetic flux. A voice coil placed in a magnetic space/gap of high flux density, which is usually also an air gap in a loudspeaker driver, interacts with the magnetic field when a signal is passed through the coil and excurses to and fro.

Voice coil:

The coiled conductive element in a loudspeaker that vibrates according to a varying electrical signal and so produces sound waves when connected to a diaphragm. Generally comprises of a coil of wire (of any geometric cross section) which is placed in a magnetic field in a magnetic space and vibrates when an audio signal is supplied to it. The voice coil generally may be wound on a cylindrical structure known as 'former'.

Diaphragm:

The element or membrane in a loudspeaker that couples with a medium such as air, producing sound waves. The diaphragm is the most significant sound producing element in a loudspeaker. Usually referred to as the cone due to the shape that is most widely used in the loudspeaker industry. However, flat, elliptical, square, rectangular, polygon and other shape diaphragms can be used as well.

Following are the components and their reference numbers

10 - Surround of diaphragm

20 - Diaphragm

30 - Connector/Connection between coil and diaphragm

40 - Coil

50 - Magnetic assembly and associated parts

60 - Suspension

70 - Supporting frame

Figure - 1 depicts a blown up view of a outer ring magnet iteration of the mirror symmetric slotted pole magnetic circuit transducer, the frame/basket is not shown to avoid confusion. Diaphragm 20 with surround 10 is coupled with an axial connector 30-A which couples with spider suspension 60, part of 30-A goes into the central portion of the mirror symmetric half of the motor made of slotted inner pole assembly 50-A coupled with axially charged magnet 50-C in turn coupled with top plate 50-B, the motor half then encloses coil assembly consisting of connector 30-B and coil 40 which connect to 30-A via the inner portion of 30-B, the other motor half then encloses the coil assembly from the opposite direction and magnetic orientation of the first motor half, hence forming the basic transducer.

Figure - 2A depicts a fundamental magnetic circuit formation with mirror symmetry axis X defining the mirror symmetric halves of the circuit where magnets 50-B are mounted to plate 50-C from opposite sides to drive magnetic flux from the plate 50-C across the gap between 50-C and return path 50-A so as to send back the magnetic flux back to both magnets 50-B . Constructional axes;

Y1 (away from the left edge of the circuit),

Y2 (along the left edge of the circuit),

Y3 (along the right edge of the circuit) and

Y4 (away from the right edge of the circuit)

define how the fundamental magnetic circuit can be rotationally formed into the actual structure.

Figure - 2B depicts the structural formation of fundamental magnetic circuit in Figure - 2A formed along constructional axis Y1, forming a hole in the centre of the formed circuit.

Figure - 2C depicts the structural formation of fundamental magnetic circuit in Figure - 2A formed along constructional axis Y2, without forming a hole in the centre of the formed circuit.

Figure - 2D depicts the structural formation of fundamental magnetic circuit in Figure - 2A formed along constructional axis Y3, without forming a hole in the centre of the formed circuit.

Figure - 2E depicts the structural formation of fundamental magnetic circuit in Figure - 2A formed along constructional axis Y4, forming a hole in the centre of the formed circuit, showing the gaps in the return path 50-A.

Figure - 3A depicts a fundamental magnetic circuit with magnets 50-B driving the drive plate 50-C from opposite sides and the flux return path 50-A.

Figure - 3B depicts Figure - 3A with 50-C and 50-A separated equally along the mirror symmetry axis X.

Figure - 3C depicts Figure - 3A with the return path divided into parts 50-A and 50-D.

Figure - 3D depicts Figure - 3A with the return path divided into parts 50-A, 50-D and 50-E.

Figure - 3E depicts Figure - 3A with the return path 50-A asymmetrically divided at parts 50-D and 50-E while the centre plate 50-C is divided symmetrically along the mirror symmetry axis X.

Figure - 4A depicts a fundamental magnetic circuit with radially magnetized magnet 50-B coupled with return path loop 50-B with mirror symmetry axis X defining the mirror symmetry of the circuit.

Figure - 4B depicts Figure - 4A with curved return path loop 50-A.

Figure - 4C is another depiction of Figure - 4A with curved return path loop 50-A

Figure - 5 depicts a fundamental magnetic circuit with two radially polarized magnet sets 50-B at opposite ends of the circuit with drive member 50-C and return path 50-A symmetrically defined by axis X.

Figure - 6 depicts a fundamental mirror symmetry circuit with drive plates 50-C separated by non-magnetic member 50-D and return path 50-A connected to magnets 50-B.

Figure - 7 depicts Figure - 6 with return path 50-A separated on either sides of the mirror symmetry axis X.

Figure - 8 depicts a fundamental magnetic circuit with two drive magnets 50-B mounted to a T shaped return path member 50-A magnetically driven by two top plates 50-C, the circuit symmetrically defined by mirror symmetry axis X.

Figure - 9 depicts a mirror symmetry transducer structure with diaphragm 20-A having surround 10 and inner apex mounted to coil-diaphragm connector 30 and coil 40 placed in space between plate 50-C and return path 50-A connected to magnets 50-B. The magnetic structure situated under the dust cap 20-B. Spider suspension 60 is coupled to the coil-diaphragm connector 30 in the plane of the coil 40.

Figure - 10 depicts phase plug 70-A mounted on one end of the magnetic structure defined by magnets 50-B mounted to plate 50-C and return path 50-A connected back to the magnets 50-B.

Figure - 11 depicts diaphragm 20-A and coil-diaphragm connector part 30 coaxially connected .

Figure - 12 depicts diaphragm 20-A and coil-diaphragm connector part 30 coaxially connected .

Figure - 13 depicts a mirror symmetric motor iteration with return path 50-A extended behind the magnets 50-B to allow for high excursion of coil 40 and diaphragm 20 coaxially connected to coil-diaphragm connector 30-A by a coaxial connector 30-B and spider suspensions 60 coupled to the coaxial connection between the diaphragm 20 and coil-diaphragm connector 30-A.

Figure - 14 depicts a mirror symmetry iteration with two axially polarized ring magnets 50-B coupled to plate 50-C and return path 50-A, with coil 40 situated inside the ring magnets and connected to diaphragms 20 via concentric ribbed connector 30-A and coaxial connector 30-B with suspensions 60 mounted to the coaxial connector which can be a cylindrical former.

Figure - 15 depicts a mirror symmetry transducer structure with two radially polarized magnets 50-B coupled to drive member 50-C and return path 50-A, with coil 40 connected to diaphragms 20 via concentric ribbed connector 30-A and coaxial connector 30-B with suspensions 60 mounted to the coaxial connectors on either ends.

Figure - 16A depicts mirror symmetric magnetic structure with axially magnetized ring magnets coupled to drive plate 50-C and inner return path 50-A magnetically driving coil 40 which is connected to diaphragm 20 placed concentrically inside the magnetic structure via coil-diaphragm connector 30.

Figure - 16B shows a front sectional view of a symmetric half of Figure - 16A with material suspensions 60 between a concentric surface of coil-diaphragm connector 30 and surface of return path members 50-A.

Figure - 17 depicts a mirror symmetry magnetic circuit with multiple radially polarized magnets 50-B situated coaxially along an inner edge of return path loop 50-A, driving coil 40.

Figure - 18A depicts multiple coil-diaphragm structures with multiple ribs 30 and combinations with slits that are encircled in the sections of the connectors.

Figure - 18B depicts how a ribbed concentric connector can be constructed using geometrically bent strips 30.

Figure - 18C depicts bent strips 30-A joined together and placed between concentric sections 30-B and 30-C to form ribbed concentric coil-diaphragm connector 30.

Figure - 18D depicts differently bent strips 30-A, 30-B and 30-C forming the concentric ribbed coil-diaphragm connector 30.

Figure - 18E depicts bent strip 30 forming a closed loop segment of a concentric ribbed coil-diaphragm connector.

Figure - 18F depicts two bent strips 30 forming a closed loop segment of a concentric ribbed coil-diaphragm connector.

Figure - 18G depicts bent strip 30 forming a open segment of the concentric ribbed connector.

Figure - 18H depicts curved strips 30-A, 30-C along with geometrically bent strip 30-B forming the concentric ribbed coil-diaphragm connector 30.

Figure - 18I depicts a single geometrically bent strip 30 forming the whole concentric ribbed connector by the virtue of the geometric pattern by which it is bent.

Figure - 19A depicts coil 40 coupled to coil-diaphragm connector rib 30 with multiple circular holes.

Figure - 19B coil 40 coupled to trapezoidal coil-diaphragm connector rib 30.

Figure - 19C depicts voice coil and former 40 coupled to coil-diaphragm connector ribs 30 on inner former surface on one end and outer former surface on the other end of the voice coil former.

Figure - 19D depicts two voice coils 40 mounted on a former and connected to ribs 30.

Figure - 19E depicts coil 40 connected to inverse trapezoidal coil-diaphragm connector rib 30 with circular hole.

Figure - 19F depicts coil-diaphragm connector ribs 30 on both surface sides of coil 40.

Figure - 19G depicts voice coil and former 40 with two mounting edges of coil-diaphragm connector rib 30 mounted on either sides of the voice coil former.

Figure - 19H depicts coil 40 connected to parallelogram shaped coil-diaphragm connector rib 30.

Figure - 20A depicts the facilitation for drawing the coil wire or connection to the coil(s) through the slotted poles of the motor structure via passage(s) 30-B incorporated aligned with the rib(s) of the coil-diaphragm connector 30-A. The geometry of the passages are not limited to the depiction in the figure, concurrently passages, slots, cuts, holes may be incorporated in the coil-diaphragm connector for alignment guidance during manufacturing assembly, venting heat, air pressure and so on.

Figure - 20B depicts the facilitation for drawing coil connection(s) 40-B through the layers of the rib(s) of the coil-diaphragm connector 30-A. The said connection(s) may be flat as depicted in the figure but not limited to flat wire configuration, although preferred in this situation. The connection(s) are sandwiched between the layers constituting the rib(s) in connector configurations made possible by joining geometrically bent strips forming the coil-diaphragm connector and facilitating sandwiching of lead connections between the layers.

Although not a limitation in any way, there are some preferred modes to practice the disclosed invention. The invention needs only one pole opening and one rib structure coupling the voice coil(s) and diaphragm(s) to function rather well, however it is preferred to incorporate more than one pole opening and more than one rib structure for voice coil-diaphragm coupling for better structural and functional stability of the transducer.

Claims

What is claimed is:

1) An electromagnetic transducer comprising:

a fundamental magnetic circuit including ;

at least two magnetic poles defining at least one magnetic gap;

at least one voice coil(s) disposed within the said magnetic gap(s);

at least one rib structure coupling the voice coil(s) to at least one diaphragm through at least one opening in at least one of the poles;

the opening(s) being substantially parallel to the direction of motion of the voice coil(s);

the fundamental magnetic circuit comprising substantially symmetric magnetic flux path(s).

2) The electromagnetic transducer of claim 1wherein the fundamental magnetic circuit comprises:

axially charged magnets coupled to at least one polar drive member facilitating substantially symmetric flux path(s) to flux return member(s) in the circuit;

said flux return member(s) forming at least one magnetic gap with the polar drive member(s).

3) The electromagnetic transducer of claim 1wherein the fundamental magnetic circuit comprises:

at least one radially charged magnet with;

at least one surface coupled to at least one flux return member;

at least one surface facilitating at least one magnetic gap with at least one flux return member;

forming substantially symmetric flux path(s) in the said fundamental magnetic circuit.

4) The electromagnetic transducer of claim 1 wherein at least one diaphragm is coupled to at least one ribbed voice coil-diaphragm coupling structure

away from the plane of the voice coil(s); and/or

in the plane of the voice coil(s).

5) The electromagnetic transducer of claim 1 wherein at least one suspension structure is coupled to at least one ribbed voice coil-diaphragm coupling structure;

away from the plane of the voice coil(s); or

in the plane of the voice coil(s).

6) An electromagnetic transducer comprising:

at least one rib structure coupling the voice coil(s) to at least one diaphragm through at least one opening in at least one of the poles;

the at least one ribbed voice coil-diaphragm coupling structure comprising at least two substantially concentric section part(s) with at least one rib part disposed within them;

said voice coil-diaphragm coupling structure assembled with at least one geometrically bent structure.

7) Ribbed coupling structure of claim 6 facilitating means to provide voice coil electrical connection(s) through:

at least one passage in the structure section(s) along at least one rib structure; and/or

the layer(s) of at least one rib structure.

8) Electromagnetic transducer of claim 1 with substantial features as depicted in any of the accompanying drawings.

9) Electromagnetic transducer of claim 6 with substantial features as depicted in any of the accompanying drawings.