JPH0560318B2 - - Google Patents

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. The invention particularly relates to a type of transducer with vibrating reeds of the type known as a "balanced armature".

In an amateur balanced transducer, a permanent magnet combines with the pole piece to create a magnetic field across the air gap, and a vibratory reed is fixed and connected to the pole piece and other parts that can vibrate in the air gap. It is equipped with. The reed is surrounded by an electrical coil, the arrangement of which is such that when the movable part of the reed is displaced in one direction or the other away from a central position between the two magnetic poles, a magnetic flux is directed along the reed. It is therefore arranged to flow in one direction or the other through the coil. The reeds are connected to a diaphragm such that vibrations of the diaphragm caused by the received sound are converted into corresponding electrical currents in the coil, or vice versa.

It is important in such armature balanced transducers that the movable portion of the lead be accurately centered in the air gap. Many proposals have been made to achieve this. However, most prior systems are inaccurate or extremely difficult to implement. In many such prior systems, this is accomplished by bending a portion of the pole piece or lead during actual manufacturing or post-manufacturing adjustment. The difficulty that arises is that movements associated with this adjustment are inevitable when the stress induced by the bending is released.

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

The present invention includes one or more magnets coupled to a pole piece structure for creating a magnetic field across an air gap, and a portion fixed and magnetically connected to the pole piece structure and vibrating in the air gap. a magnetic vibrating reed having a magnetic vibration reed and a coil surrounding the reed, such that vibration of the reed within the air gap influences the current in the coil, and vice versa. The present invention relates to an amateur balanced electroacoustic transducer.

According to one aspect of the invention, an abutment surface is formed on the pole piece structure, which acts against a fixed part of the reed in order to position the reed with respect to the air gap in the direction of vibration. In a converter of the type previously mentioned.

Preferably, the contact surface on the pole piece structure is approximately in the same plane as the central plane of the air gap. It is also desirable for the pole piece structure to form a ring surrounding the air gap, and it is also desirable for the abutment surface that determines the position to be external to the ring.

In a particularly preferred construction, the lead is E-shaped and has two outer legs 16, 17 lying substantially parallel to the central leg, which outer legs have coplanar abutment surfaces on the ring. The central leg is allowed to vibrate within the air gap. According to another advantageous characteristic of the invention, the pole piece structure is laminated, each laminated layer forming a part of the impact surface. The laminations extend in a plane perpendicular to the vibrating reed and are each in the shape of a ring. Alternatively, the stack may extend parallel to the length of the lead.

In any case, it is advantageous for the transducer to have two permanent magnets each placed on either side of the air gap, each of these being connected to a part of the pole piece structure.

According to another aspect of the invention, a transducer of the type described above has a laminated pole piece structure;
Each of the laminations creates a complete magnetic flux path between the opposing magnetic poles, with which the structure is also connected to the fixed portion of the lead.

According to still another aspect of the present invention, in the transducer described above, the entire lead is flat and coplanar, or even if bent, the release of the bending stress is at the position of the movable end of the lead. It is bent so as not to affect it.

According to another desirable feature of the invention, the magnetic flux path remains the same no matter which direction the reed oscillates.
extending through the pole piece junction.

Although the present invention can be implemented in various embodiments, two embodiments will be described herein by way of example with reference to the accompanying drawings.

In the first embodiment shown in FIGS. 1 and 2, the transducer consists of a number of parallel flux-conducting laminates with rectangular apertures 9 that connect the surfaces. It consists of a stack or assembly 10 of pole pieces brought together to form a central passage or tunnel. Within this tunnel there are upper and lower permanent magnets 11, 12 which are fixed to adjacent parts of the stack and both magnetized in the same perpendicular direction with the N-pole at the top as seen in the figure. It is something that This creates a strong magnetic field that extends vertically across the air gap between the magnets, which then splits into sections of the stack above and below the magnets, and then loops further toward the other leg of the pole piece. It is something that creates

That is, the magnetic flux caused by the permanent magnet is made not to pass through the base portion of the reed or the fixed contact surface, but only through the gap and the tip of the vibrating reed.

Each laminate is formed with protruding wings 13 on both sides, each wing having one flat top surface 14.
, whose upper surfaces are precisely set to lie parallel to one central horizontal plane that passes exactly through the center of the air gap between the magnets (with a deliberately small difference, as explained below). During manufacturing, the inner corner of the opening 9 and the corner of the wing 13 became rounded, which made the magnet 1
1, 12 and the curved legs 16, 17 may cause slight errors in positioning. For this reason, it is desirable to make a small cut at each corner, as shown at 15.

The transducer armature is generally E-shaped with two parallel legs 16, 17 and a central leg 18 forming the vibrating reed. The armature portion 19 interconnecting the three legs is bent downward by 90°,
Improves stiffness and reduces overall dimensions. The ends of the two fixed legs 16, 17 are fixed to the flat surface 14 of the laminate wing, for example by welding. The tip 20 of the vibrating leg 18 is placed between the two magnets 11, 12, and the vibrating leg is surrounded by a coil 22, which is 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 amplifier when used as a microphone or to a supply circuit when used as a handset.

The three legs 16, 17, 18 are quite 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 needs to be below the central position by half the thickness of the leg. This position setting is similarly adopted for the position of the surface 14 of each pole piece stack.

It should be noted that each of the legs 16, 17, 18 is bent with respect to the connecting leg 19;
The bending is in the same direction for each leg. Therefore, when the bending stress in one leg is released, the same will occur in the other leg, thus keeping the three legs parallel in a common plane, thus reducing the vibration The tip 20 of the lead is to be kept in the center of the air gap at all times.

Note that the pole piece laminates do not bend during fabrication and assembly, as was done in some prior art transducers, and the locating surface 14 is precisely machined or removed from the integral laminate. It is punched out, thus providing a completely accurate locating surface.
This means that slight inaccuracies in placing the legs 16 on the positioning surface will not significantly affect the positioning of the central lead tip 20.

In a second embodiment illustrated in FIG. 3, the pole piece assembly 30 is generally J-shaped and includes a stack of magnetic flux conducting laminates, each laminate being one of the laminates.
A main leg portion 31 having a hook portion (hook portion) 32 at one end and an anvil portion (anvil portion) 33 at the other end.
has. A pair of permanent magnets 34, 35 are positioned between the hook portion 32 and the main leg 31, the magnets being polarized in the same direction and spaced apart to form an air gap. The vibrating reed is a simple flat plate 36, one end of which is fixed to the top surface 37 of the pole anvil portion 33, and the other end of which is attached to two magnets 34, 3.
It is centered between 5. Lead is coil 3
8 and attached to the acoustic diaphragm by links (not shown).

For the reasons discussed above, it is important that the movable end 40 of the lead be accurately centered within the air gap. For this purpose the stack of pole pieces is arranged such that the upper surface 37 of the anvil portion is flush with its lower surface when the lead end 40 is centered.
Formed during manufacturing. Since the lead is a simple flat plate with no bends, and the pole piece laminates are likewise free of bends in fabrication or assembly, there are no stress reliefs that introduce inaccuracies and no special adjustments. Accurate lead centering is possible without the need for any additional steps.

Note that in any of the embodiments described above, each laminate of pole pieces defines one complete flux path between the fixed end and the movable end of the armature or lead. What should be further noted is that
In use, magnetic flux continues to pass through the joint between the armature and the pole piece stack in either direction even as the direction of the magnetic flux along the lead changes. 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 a first embodiment of a transducer according to the invention. FIG. 2 is a 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, 1
4... Collision surface, 11, 12, 34, 35... Permanent magnet, 13... Wing, 16, 17... Outer leg, 18... Center leg, 19... Connection leg, 20
...Lead tip, 22, 38...Coil, 31...
...Main leg part, 32...Hook part, 33...Anvil part, 37...Top surface of anvil part, 40...
Movable end of lead.

Claims (1)

Claims: 1. A pair of permanent magnets 11, 12; 34, 35 spaced apart to form an air gap; a pole piece structure 10; 30 for setting the magnets to form a magnetic path across the air gap; , one part 16, 17 fixed to the pole piece structure and the other part 18; 40 capable of vibrating in the air gap, both parts being flat and in a common plane; In an armature-balanced miniature electroacoustic transducer comprising a wound coil 22; 38, arranged such that vibrations of the reed in said air gap influence the current in said coil, and vice versa, The pole piece structure is formed to have contact surfaces 14, 9 with respect to the reed and the pair of permanent magnets, and the reed contact surface 14 is approximately equal to half the lead thickness from the center plane of the air gap. The pole piece structure is a rigid body and is in direct contact with the pair of permanent magnets and the fixed part of the lead, and the pole piece structure is integrally formed. The laminate is of a laminated type, and the laminate extends continuously between both ends of the lead forming the contact surface and the mounting surface of the magnet. An amateur balanced compact electroacoustic device, which is arranged so as not to pass through the plane, each layer of the laminate extends perpendicularly to the plane of the vibrating reed, and the vibrating part of the reed is positioned at the center of the air gap. converter. 2. Transducer according to claim 1, characterized in that the pole piece structure 10 constitutes a ring surrounding the air gap. 3. Transducer according to claim 1, characterized in that the abutment surface 14 for setting the position of the lead is external to the ring. 4. The reed is E-shaped and comprises a central leg 18 and two outer legs 16, 17 lying approximately parallel to it, the outer legs being fixed to a coplanar abutment surface 14 in said ring, Transducer according to claim 2 or 3, characterized in that the part 18 is capable of oscillating within the air gap. 5. A transducer according to any one of claims 1 to 4, wherein the stacks of laminates extend in a plane perpendicular to the vibratory reed 18, and each stack is in the shape of a ring. 6. A transducer according to any of claims 1 to 4, wherein the stack of laminates extends parallel to the length of the lead 18 but perpendicular to the plane of the lead. 7. Claim in which each of the stacks of pole piece structures forms a complete magnetic path between the pole pieces, and the structures extend to form an abutment surface portion that is a fixed portion of the lead. The converter according to any one of the ranges 1 to 6. 8. A transducer according to any one of claims 1 to 7, in which the magnetic path extends through the same lead/pole piece junction when the leads vibrate. 9. The transducer according to any one of claims 1 to 8, wherein the entire lead is flat and coplanar. 10. The transducer according to any one of claims 1 to 9, characterized in that intermediate portions between the fixed portion and the vibrating portion of the lead are bent in the same way at the same position.