DE1222982B - Electromagnetic miniature transducer, especially for hearing aids - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

H04r

German class: 21 a2-1 / 01

Number: 1222 982

File number: J 24451 VIII a / 21 a2

Filing date: September 20, 1963

Opening day: August 18, 1966

The invention relates to an electromagnetic miniature transducer, in particular for hearing aids, the Magnet system accommodated in a housing comprises an armature having a plurality of arms, at least one of which has its end between the spaced poles of the magnetic DC circuit in support of the armature is firmly clamped, while the free end another arm oscillates in the working air gap between the poles.

An electromagnetic transducer is known in which a transverse permanent magnet is arranged at one end of the magnet system, from whose pole faces go out from pole plates, their free ends to form a fastening and working air gap are angled towards each other. The gaps are in a row parallel to the permanent magnet. The E-shaped anchor protrudes with the free ends of its three arms into the adjacent ones Column and is either with its middle or with its two outer annen with help clamped by intermediate pieces between the bends of the pole plates, while each free arm can swing freely between these bends. The armature protrudes from the columns to the magnet facing away from the magnet system. The connecting web of the anchor can then, if the both outer arms are clamped, are fixed by a screw, so that vibrations are limited to the middle arm only. If only the middle arm is clamped, the anchor should mainly perform torsional vibrations. In this case, a attached to the connecting web Torsional vibration rod be guided in bearings to avoid vibrations other than torsional vibrations to prevent.

There is also an electromagnetic transducer, in particular a receiver or microphone known, in which an approximately strip-shaped armature surrounded by a stationary coil is firmly clamped at one end and freely oscillates at its other end in the air gap between two poles of a magnet system. In order to obtain the smallest possible dimensions, as they are, for. B. are required for hearing aids, it is provided in this known converter that the magnet system consists of an approximately U-shaped, one-piece bracket made of ferromagnetic material, the free leg ends are connected on their inside with a permanent magnet. The permanent magnets form the working air gap between them. The one with the coil inside the electromagnetic miniature transducer,
especially for hearing aids

Applicant:

Industrial Research Products, Inc.,

Franklin Park, JU. (V. St. A.)

Representative:

Dr. J. Fricke, patent attorney,

Munich 2, Josephspitalstr. 7th

Named as inventor:
August F. Mostardo jun.,
Norridge, JH .;
Floyd W. Cross,
Wheaton, JIl. (V. St. A.)

Claimed priority:

V. St. ν. America July 29, 1963 (298 332)

Stirrup arranged strip-shaped anchor is with its one end at or in the vicinity of the two Legs connecting the base of the bracket attached with low magnetic contact resistance. to for this purpose, the anchor end can be bent at right angles and attached to the base or a form the notched part of the bracket itself. This ensures that the strip-shaped anchor can swing practically in the full length of the arms of the yoke. So at the junction there is no great resistance to the magnetic flux between this bracket and the armature, in the case where the two parts are separate parts, the angling of the anchor provides a large contact area, which can be omitted with one-piece training.

In contrast, the present invention relates to a different type of transducer in which - as at the beginning - instead of a strip-shaped anchor, an E-shaped anchor is provided. With such a the problems outlined for the strip-shaped anchor do not exist because of the pinch point of the armature does not touch the freely oscillatable length of the armature at all and

609 610/276

3 4

enlargement of the transducer dimensions does not cause F i g. 1 shows in an exploded view

is and the clamping points always only a small one converter according to the invention;

Have contact resistance. F i g. 2 is a perspective view of a

The invention, however, is concerned with a transducer only as shown in FIG. 1, with the outer housing

in transducers of the aforementioned type 5 and other parts have broken away to the inner

occurring problem, namely to reveal the advantageous structure;

Accommodation of the arms of the multi-armed F i g. 3 is a sectional view showing the section

Anchor connecting, essentially freely oscillating along the section line III-III in F i g. 2 is drawn,

facing bridge. This bridge has the in during converters

The genus in question with the clamping of the io Fig. 4 is a perspective view of the

Armature or armature used with the transition of the magnetic flux new arrangement.

from one part to the other part of the magnet- In the drawings, the inner assembly 10 is

systems to do nothing. Its only task is to represent a converter within a housing,

the three arms of the armature mechanically and magnetically, one bottom section 12 and one cover 14

to connect to one piece. He represents an area 15 includes. The inner arrangement 10 comprises a ma

of the vibrating part of the armature. Magnetic stack 15, the armature 16, the signal coil

It is the object of the invention to provide a transducer from FIG. 18 and the membrane element 20.
The magnetic drive part comprises a manentmagnet 24 which extends transversely by simple means with a rod-shaped peculiarity of the armature by means of precise determination 20. Above the position of a vibration node, the magnet is improved and at the same extent with this, while reducing the distance, a lower pole piece 26 made of magnetic diameters of the transducer is arranged in the direction of the longitudinal material. Above the pole center line of the armature and in the vertical direction, piece 26 is spaced at both ends from the plane of the armature, 25 pieces 28 made of non-magnetic material.

This object is seen according to the invention. These spacers at the end

solves that the web connecting the arms of the armature are mounted above the pole piece 26 and serve

bent at right angles out of the plane of these arms to support the outer side arms 30 and 32

is and is approximately parallel and freely movable un- an E-shaped armature 16. These outer arms

extends indirectly along a wall of the housing. 3 ° are mounted on the spacers, with a

It is readily understood that this second pair of equal spacers 34 permanently

Further development the dimensions of the oscillatable provided above each of the outer armature arms

Anchor part is around in the direction of its longitudinal center line. Above the top spacers 34 is a

the width of the angled web can be shortened. second, transversely extending pole piece 36 with the same

The same shortening also occurs in the converter 35 rather expansion than the lower pole piece 26 and

housing on. The shortening is considerable since the lower permanent magnet 24 is provided. That

Web for mechanical and magnetic reasons, the last link of the stack 15 is replaced by a second

must have a noticeable width. In addition, permanent magnet 38 is formed in the shape of a rod, which is shown in

is used to bend the connecting web to the transverse direction is magnetized, as is also the case for the

stiffening of the anchor in the transverse direction. This adjustment 4 ° lower magnet 24 applies. The stack is as a unit

At the same time, fung establishes the point of vibration by means of appropriate glue, rivets or

or the junction line in the vicinity of the turn is summarized and fixed in a similar way,

notice. This gives an improvement The magnets are, as mentioned before, in transverse

the action of the unit by magnetizing the occurring direction so that the upper surface 40

Vibrations more on the one with its end not 45 of the lower magnet 24 a uniform pole, z. B.

clamped anchor arm are concentrated. Since it has a North Pole. If it is assumed

Length of the movable armature part becomes smaller, is that the upper surface 40 of the lower magnet 24 is a

also the deflection of the base web is perpendicular to the north pole, forms the lower or bottom surface of the

Anchor plane lower than in the known wall magnets 38 a south pole, which pole of the surface 40

where the web is in the anchor plane. 50 opposite.

The armature 16 is, as already mentioned, E-shaped

Free space above and below the bridge is required. formed and has two outer arms 30 and 32,

It is advantageous if the oscillating which are fixed in the magnet stack 15 while

Anchor arm via a drive pin with a membrane, the middle arm 24 through the stack into one

is connected, the connecting web of the armature protrudes after 55 working gap 44, which is formed in that

bent on the side of the membrane, since on this in the middle transverse area of the stack the

On the side there is no more space to accommodate the footbridge. Through this training

is available. So the magnet stack can expediently stretch vertically and transversely

Armature as well as all other the magnetic alternating direction, the armature 16 from the stack in

flux-carrying parts of soft magnetic, which protrudes 60 middle height.

Housing of the transducer forming parts of the equal over the oscillating armature arm 42 is between

be enclosed in the flux circle, the bent the stack and the base portion 50 of the armature

Bar arranged in a recess of a signal coil 18 between a magnet. This coil is through

system and membrane extending wall of the corresponding lines 52, which through openings 53

house protrudes. 65 rn are out of the housing, with a power source

The discovery. is subsequently connected to the hand. The coil 18 generates a mamatic during operation Drawings of an embodiment of the magnetic field which can be found in the axis of the coil explained. is centered. The swinging anchor arm 42 extends

through the coil 18, in the rest position along the coil axis, and serves to to pick up the field generated by the coil.

An intermediate wall 54 is provided on the upper surface of the upper magnet 38 by appropriate means attached, which is made of magnetic material and has a width sufficient to allow the wall can be firmly received in the housing 12. This partition can also be used in a suitable manner with the peripheral surface of the coil 18 by an appropriate adhesive or other binding agent be connected. The partition protrudes from its junction with the magnetic stack and extends at a distance parallel to the anchor arms. On the edges that are place farthest away with the stack of magnets, the partition 54 ends in two parallel, mutually spaced projections or tongues 56 which are formed so that they are attached to the abut the adjacent wall of the housing 12 and thus hold the magnetic arrangement in the housing. Between these projections, the intermediate wall comprises a cutout 60, which one Part of the vibrating armature arm 62 leaves free. Through the recess 60 protrudes in the vicinity of the inner End of the recess of the drive pin 62 which connects the oscillating arm 42 to the diaphragm 20. The drive pin 62 is in a corresponding manner, for example by welding or gluing connected to the swinging arm. The drive pin extends through the recess 16 so it can be connected to the membrane in a corresponding manner. At the end 64 of the recess, which is furthest away from the stack, the cutout is kept correspondingly wide, so that the base portion 50 of the anchor can be moved easily and freely.

At the end remote from the stack, the anchor arms 30,32 and 42 are through the Base section 50 connected to one another. This base section is bent so that it is below the substantial right angle to the plane of the anchor arms 30,32 and 42 runs. This basic section 50 extends upward into the region of the recess 60 at the end 64, namely within the projections 56 of the intermediate wall. The upturned base portion 66 of the anchor serves different purposes. First of all, this bend forms a stiffening of the to a limited extent Anchor structure, thereby preventing the outer arms 30 and 32 from vibrating to a certain extent. This vibration suppression is an aid to the vibration node of the middle arm 42 to set in the vicinity of the bent edge 66 of the anchor base 50. This setting of the vibration node The result of the anchor leads to a greater effect of the unit by reducing the vibratory forces acting on the vibrating arm act, can be used to a greater extent to exclude movement of the middle arm to cause. In addition, the bend 66 of the armature reduces the linear length of the housing, so that a more compact and substantially narrower housing than before is obtained. In the Cases where the base portion of the anchor extends in the same plane as the anchor arms, Sufficient space must be left above and below the base section so that a free Movement of the anchor is allowed. However, this additional space contributes to the functioning of the Unity, in particular, little contributes to its performance. By bending the anchor base perpendicular to the anchor arms this space is reduced to a minimum, so that an even smaller one or shorter converter housing can be used than before.

The membrane element 20 includes a rectangular frame 70 which is dimensioned so that it is firmly held in the side walls of the housing. The frame has a flange ' 72, which has a stepped cross-sectional shape, around the membrane at a distance from the intermediate wall 54 to keep. The membrane frame rests on the intermediate wall 54 in order to ensure precise alignment of the Ensure element in the housing. The membrane frame has an oval layer 74 plastic material, which is attached to the flange 72 inwardly. Inside this in the Center open plastic layer, which may be referred to as rim 74, is on the plastic Material an oval-shaped membrane made of aluminum or similar material attached. These The membrane is oval-shaped and light in weight so that it can move to a limited extent. can run in a plane that is perpendicular to the plane of the membrane. This movement will made possible by the aid of the plastic enclosure 74. In its center is the membrane 76 with the Drive pin 62 connected to allow motion transmission. Through this training the membrane element 20 can be produced as an integral unit which is essentially planar and has a support frame 70 with the ' Has flange 72, the resilient skirt 74 allowing movement and in the middle The actual membrane 76 receives the area.

Near the magnetic stack, outside of it, is on the inner motor unit an inertance tube 80 is attached. This tube 80 is L-shaped and has a horizontal one Section 82 which runs approximately parallel to the lower magnet 24 and in the vicinity thereof. The pipe is bent over in a vertical section 84 which is passed through a corresponding circular opening 86 in one corner of the membrane frame 70 protrudes to end slightly above the membrane. The function of this pipe is generally known and therefore does not need to be described in more detail here will.

To complete the device, a housing cover 14 is provided, the lower edge of which strikes against the upper edge of the housing 12 and encloses the motor unit 10. The lid may be cemented in place or otherwise attached to the housing to cover the whole To connect arrangement to a unit that can not be taken apart so easily. This protects the interior against unauthorized access. The housing itself has corresponding narrow openings for the coil ends and an adjustment opening 90 near the rear End of one of the outer armature arms to allow adjustment of the armature. Farther the lid 14 can have a single narrow circular opening 64 in the. Have lid center to the Sound waves enter the sound chamber between

the cover 14 and the membrane 76 to enable. Instead of the opening 94, other openings for the supply or discharge of the sound waves can be provided in the housing.

; In order to obtain an even better reproduction characteristic, the base section 50 of the anchor be fixed relative to the housing by an optional support 96 extending from the Base portion of the anchor 50 for manufacture. a connection with the housing extends. These Support can be designed as a shoulder-like solid element, which is fixed, for example by adhesive or attached to both anchor base 50 and housing 12 by welding. the Use of such a support would further reduce the tendency of the anchor base 50 to vibrate while reduce the swinging motion of the arm 42. It is understandable that using a such support the vibration node of the anchor slightly behind the rear End of the coil is near the armature base. The support can also be attached to the housing instead of the Be fixed intermediate wall 54 or the coil.

The arrangement and design of the magnet parts as well as the proportions are in an older one Patent application described in more detail, so that a further description is not necessary at this point.

The signal flow or the field generated by the coil 18 is transmitted via the armature 16 and the pole pieces 26 and 36, which are completely within the internal order, are closed. The steady flow that Generated by the permanent magnets is created by the magnet stack, the magnetic housing and the upper partition wall 54 closed. As previously mentioned, magnets 24 and 38 stand, respectively directly or with the interposition of a soft iron part with the housing 12 and the partition 54 in contact to complete the magnetic circuit. This is how the signal flow circuit is isolated from the DC circuit, the DC circuit through the use of the housing and the intermediate wall surrounds the signal flow circuit. The DC circuit magnetically shields the internal arrangement of magnetic stray fields. Any stray field that hits the housing can cause the Operation of the vibrating armature and the signal flow circuit of which the armature forms a part, in no way affect. On the other hand, you can also start from the motor unit Stray fields do not push outwards and therefore have no influence on devices or devices in close proximity Exercise device parts.

The purpose and uses of the upper partition wall 54 are manifold. First of all, this partition is used to close the DC circuit around the coil and the armature. Still allowed the shape of the partition wall provides the drive pin with a free passage to the connection point the membrane. This shape also creates the ability for the armature to move freely together with its angled base portion 50, without any hindrance occurring. The ones on the ends provided projections 56 of the intermediate wall serve to hold the arrangement in the housing and to ensure the required distance. Furthermore, the partition serves as a fixed link on which the frame of the membrane can be placed. The arrangement shown allows easy assembly of components, sized and shaped in such a way, that they fit with little play in the housing and on the adjacent elements or components issue.

Claims (5)

Patent claims: 1. Electromagnetic miniature transducer, especially for hearing aids, whose in a Ge ^ The magnet system accommodated in the housing comprises an armature having a plurality of arms at least one with its end between the spaced poles of the magnetic DC circuit in support of the armature is firmly clamped, while the free 'The end of another arm swings in the working air gap between the poles, thereby characterized in that the web (50) connecting the arms of the armature is bent approximately at right angles from the plane of these arms and extends approximately parallel and freely movable directly along a wall of the housing. 2. miniature transducer according to claim 1, wherein the oscillating arm of the armature via a Driving pin connected to a membrane arranged approximately parallel to and at a distance from the armature is, characterized in that the connecting web (50) to the side of the membrane (76) has turned. 3. Miniature converter according to claim 2, characterized in that the armature and all others the magnetic alternating flux leading parts of soft magnetic, the housing of the transducer forming parts of the constant flux circuit are enclosed and the bent connecting web in a recess between a magnet system and membrane extending wall (intermediate wall 54) of the housing protrudes. 4. Miniature converter according to claim 1 to 3, characterized in that the armature in on is known to be E-shaped and pinched the ends of the outer legs while the end of the middle leg can swing freely in the working air gap. 5. miniature transducer according to claim 1 to 4, characterized by an inside the housing arranged support element (96), which supports the anchor approximately in the area of a node. Considered publications:
German Auslegeschrift No. 1 086 748,
542;
U.S. Patent No. 2,454,425. 1 sheet of drawings 609 610/276 8.66 © Bundesdruckerei Berlin