JPS58215897A - Electroacoustic converter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electroacoustic transducer, which is used in a microphone for converting sound energy into electric current, or in a loudspeaker or telephone receiver for converting electric current into sound. It is something. The invention particularly relates to a type of transducer with moving leads of the type known as a "balanced armature".

In a balanced armature transducer, a permanent magnet is coupled to the pole pieces to create a magnetic field across the air gap, and a vibratory reed is fixed and connected to the pole pieces and vibrates in the gap. It is attached with a Urusen part. The reed is surrounded by an electrical coil, the arrangement of which allows magnetic flux to flow along the reed as the moving part of the reed is displaced in one direction or the other away from a centered position between the two magnetic poles. and thus arranged to flow in one direction or the other through the coil.

The reeds are attached to the diaphragm, and the vibrations of the diaphragm caused by the sound thus received are converted into corresponding electrical currents in the coil, and vice versa.

What is important in such a balanced armature converter is that
The movable part of the lead should be accurately centered in the air gap. There are many proposals to achieve this. However, most prior systems are inaccurate or extremely difficult to implement. Many such systems rely on bending portions of the pole pieces or leads during the actual manufacturing process or during subsequent adjustment steps. Other difficulties arise in this case from the unavoidable movements associated with adjustment when the stress induced by bending is relieved.

It is therefore an object of the present invention to provide an improved, balanced armature transducer with accurately centered leads that is relatively simple to manufacture and assemble.

The present invention includes one or more magnets coupled to a pole piece structure to create a magnetic field across the air gap, and a portion fixed and magnetically connected to the pole piece structure and within the air gap. a vibrating magnetic reed having a coil surrounding the reed, the vibration of the reed in the air gap affecting or causing the current in the coil; The present invention relates to an electroacoustic transducer with counterbalanced armatures arranged in reverse.

The present invention provides that, in the - plane, an abutting surface is formed on the pole piece structure, which acts as a position relative to the fixed part of the reed in order to select the position of the reed with respect to the air gap in the direction of vibration; A converter of the above-mentioned type is used.

Preferably, the adjacent surfaces on the pole piece structure are substantially coplanar with the central plane of the air gap. It is also desirable to provide a ring in which the pole piece structure surrounds an air gap, and it is also desirable for the adjacent surfaces for position selection to be external to the ring.

In a particularly desirable construction, the lead is E-shaped and has two outer legs (16
, 17), the outer legs being fixed to coplanar adjacent surfaces on the pole ring, and the center leg being able to vibrate in the air gap. According to another advantageous feature of the invention, the fragment structure is a laminate, each laminate being formed to provide a portion of an adjacent surface. The stacks extend in a plane perpendicular to the vibratory reeds and each can be in the shape of a ring.

Alternatively, the laminations can run parallel to the length of the leads.

In any case, it is advantageous for the transducer to have two permanent magnets each positioned on opposite sides of the air gap, each of which is connected to a part of the pole piece structure.

In another aspect of the invention, a transducer of the type described above has a stacked pole piece structure in which each stack provides a complete flux path between opposite poles of the pole piece. However, the structure is also connected to a fixed portion of the lead.

In yet another aspect of the invention, in the transducer described above, the leads are flat or the bending stress relief does not affect the position of the vibrating end of the lead. It is bent so that it does not.

According to another desirable feature of the invention, the magnetic flux paths extend through the same lead/pole piece junction when the reeds vibrate in either direction.

While the invention may be implemented in various ways, two embodiments will now be described by way of example with reference to the accompanying drawings.

In the first example shown in FIGS. 1 and 2, the transducer is
Consisting of a pole piece stack or assembly 10 consisting of a number of parallel flux-conducting stacks with rectangular openings 9, brought together in parallel to form a central passage or tunnel. be.

Inside this tunnel there is an upper or part of the permanent magnet 11.1.
2, which are fixed to adjacent parts of the stack and both magnetized in the same direction, vertically with the N-pole at the top as seen in the figure. This creates a strong magnetic field that extends perpendicularly across the air gap between the magnets, which then splits into sections of the laminate above and below the magnet, and loops around the other leg of the pole piece. It is something.

Each stack is formed with protruding wings 13 on opposite sides, each wing having one flat top surface 14, which top surface has a central horizontal plane passing through the exact center of the air gap between the magnets. It is placed exactly so that it lies on the same plane and parallel to it (there is a deliberate small deviation there, as will be explained below). Wings 13 in the inner corner of the opening 9 and in the stack during fabrication
So that it has a radius, it is a magnet) 11°12
It is possible to introduce small errors in the positioning of the legs 16 and 17 of the curvature.For this reason, the corners are
It is desirable to form it with a small cut as shown in .

The converter armature generally has two parallel legs 16.17
and a central leg 18 constituting a vibrating reed.
-It is a shape. Part 1 of the armature interconnecting the three legs
9 is bent 90° downward to improve stiffness and reduce overall size. two fixed legs 16,
The ends of 17 are fixed to the flat surface 14 of the wing of the laminate, for example by welding. The tip 20 of the vibrating leg 18 is placed between two magnets 11.12, and the vibrating leg is surrounded by a coil 22, which can be mounted on the bottom plate 23 of the transducer. .

The vibrating leg 18 is connected by a link to a diaphragm (not shown) and the coil is connected to an intensifier when used as a microphone or to a supply circuit when used as a handset.

All three legs 16, 17, 18 are carefully and deliberately placed on a common plane. Since the tip 20 of the central leg needs to be equally spaced from the two magnets 11.12,
Its underside should be located below the center position by half the thickness of the leg. This location is determined by the surface 14 on each pole piece stack.
It is also adopted in the same position.

Note that each of the legs 16, 17, 18 is bent with respect to the connecting leg 19, but the bending is in the same direction for each leg. Therefore, when the bending stress is relieved in one leg, the same will occur in the other leg, thus leaving the three legs parallel in a common plane9, thus at the tip of the vibrating reed. 20 in the center of the varnish gap.

Note that the pole piece stacks are not bent during fabrication and assembly, as occurs in some prior art transducers;
The locating surface 14 is precisely machined or stamped from the laminate, thus providing a highly accurate locating surface. Small inaccuracies in positioning the legs 16 on the surface do not significantly affect the positioning of the central lead tip 20.

In a second example illustrated in FIG. 3, the pole piece assembly 30 is generally J-shaped and includes a stack of magnetic flux conducting laminations, each lamination having a hook portion at one end thereof. 32 and a main leg 31 with an anvil 33 at the other end. A pair of permanent magnets 34 and 35 connect the hook 32 and the main leg 31.
, the magnets being polarized in the same direction and spaced apart to form an air gap f. The vibrating reed is a simple flat plate 36, one end of which is connected to the pole anvil 3.
3, and the other end is fixed to the top surface 37 of the magnet 34.
It is centered between 35.

The leads are surrounded by coils 38 and attached to the acoustic diaphragm by links (not shown).

For the reasons discussed above, it is important that the moving end 40 of the lead be kept squarely within the air gap. To this end, a stack of pole pieces is formed during fabrication such that the upper surface 37 of the anvil lies flush with its lower surface when the lead end 40 is centered. Since the lead is a simple flat piece of IA with no bends, and the pole piece stacks are likewise free of bends in fabrication or assembly, there is no stress relief to introduce inaccuracies, and the precise centering of the lead The arrangement does not require any special adjustment procedures.

It should be noted that in any of the above embodiments, each individual stack of pole pieces is designed to provide one complete magnetic flux path between the fixed end and the moving end of the lead. be.

It is further noted that in use, as the direction of the magnetic flux along the leads changes, the flux continues to pass in either direction through the joint between the armature and the pole piece laminations. . Thus, any differences in the magnetic properties of the weld or joint will not affect the operation of the device.

[Brief explanation of the drawing]

FIG. 1 is a simplified perspective view of one form of a transducer according to the invention. FIG. 2 is another perspective view of the transducer from the other end. FIG. 3 is a perspective view of the second embodiment. 9... Opening 10, 30... Pole piece structure 14... Adjacent surface 11.12, 34.35.
...Permanent magnet 13...Wing 16.17...
・Outer leg portion 18...Center leg portion 19...Connection leg portion 20...Lead tip 22.38...Coil 3
1... Main leg part 32... Hook part 33...
・Anvil 37...Top surface of the anvil 40...
End part Fig. 1 7J Fig. 2 Fig. 3vlI

Claims (1)

Claims: 1) one or more magnets (11, 12, 34, 35) coupled with a pole piece structure (10, 30) to form a magnetic field across the air gap, and a core pole; A vibrating magnetic reed having a portion (16° 17) fixed and magnetically connected to a piece of structure and another portion (18) capable of vibrating in an air gap, and a coil surrounding the reed. (
22) in a balanced armature electro-acoustic transducer which is arranged in such a way that vibrations of the reeds in the air gap influence the current in the coil and vice versa; an abutment surface (14) is formed on said pole piece structure and a fixed portion (16, 1) of said reed is formed for positioning said reed with respect to said air gap in the direction of vibration;
7) A balanced 111 armature electro-acoustic transducer, characterized in that it serves as a position selector. 2) A transducer according to claim 1, wherein the adjacent surface (14'l) on the pole piece structure is approximately the same plane as the central plane of the air gap. 3) The pole piece structure (10) 3. A transducer as claimed in claim 1 or 2, providing a ring surrounding the gap. 4) A transducer according to claim 3, in which the position-selecting abutment surface (14) is external to the ring. 5) The lead is E-shaped and comprises two outer legs (16, 17) lying approximately parallel to the central leg (18), the outer legs lying coplanar on the pole ring with adjacent surfaces (14); )
Transducer according to claim 3 or 4, wherein the central leg (18) is able to oscillate in the air gap. 6) A transducer according to any of the preceding claims, wherein the pole piece structure (10) is a laminate, each laminate being shaped to form part of an adjacent surface (14). 7) A transducer according to claim 6, wherein the stacked layers extend in a plane perpendicular to the vibratory reed (18) and are each in the shape of a ring. 8) Transducer 0 according to claim 6, in which the laminations of the stack run parallel to the length of the lead (18). 9) Two permanent magnets ( 11, 12), each of which is connected to a part of the pole piece structure. 10) The above claims wherein the pole piece structures are stacked, each stack forming a complete magnetic flux path between opposite magnetic poles of the pole pieces, and wherein the structure is also connected to a fixed portion of the lead. A converter according to any of the above. 11) Any of the preceding claims, wherein the IJ-de is flat or bent in such a way that the reduction of bending stress does not affect the position of the vibratable end (20) of the reed. Converter described in Crab. 12) A transducer according to any of the preceding claims, wherein the magnetic flux path extends through the same reed/pole piece junction when the reed oscillates.