JPH07193892A - Electroacoustic transducer - Google Patents

Abstract

PURPOSE: To suppress undesired resonance by covering a vibrating part of a transducer partially or entirely with a layer consisting of fibers partially coupled with each other and a layer consisting of fibers which are simply and partially brought into contact with each other. CONSTITUTION: An attenuation layer is supported by a vibration coil conductor by which vibration is attenuated at one side and supported on a position where an entire acoustic transducer is assembled at the other side. In the attenuation layer, a mesh body consisting of threads 10, 11 which are partially coupled with each other and threads 12, 13 which are simply and partially brought into contact with each other at a contact point 14, contribute to attenuation of diaphragm motion by mechanical friction. These fibers are simply and partially coupled with each other, as a result of a relative motion between each other and due to the air included in a mesh, energy is removed from the vibrating part by friction of fluid in motion of the mesh and a higher vibration mode is strongly attenuated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to electroacoustic transducers.

[0002]

BACKGROUND OF THE INVENTION A frequent problem with electroacoustic transducers is that at a given frequency, mechanical resonances appear which interfere with normal use of the transducer.
These resonances are either from the diaphragm of the transducer itself when the partial vibrations appear above the fundamental resonances, or from mechanically coupled components such as the vibrating coil connecting wire
Alternatively, it can also occur from acoustically coupled transducer elements, such as casing walls. These vibrations are unwanted,
This is because they are perceived as noises like beats and bells due to the significantly higher Q of the resonator. In particular, the plunger coil wire is also mechanically dangerous due to this kind of resonance, since in this case a high amplitude is generated, which stresses the point of causing fatigue failure.

[0003]

An object of the present invention is to suppress this unwanted resonance.

[0004]

This problem is solved according to the invention in the following way, i.e. because the transducer parts of the transducer are partially or wholly partly connected to one another. And a layer of fissures that are only in partial contact with each other.

Many proposals have already been made for the purpose of damping the natural vibration of the diaphragm. Most solutions are the shape of the diaphragm, the material properties of the diaphragm, and
Intended for covering diaphragms with soft materials.

For example, Austrian Patent Publication No. 23827
No. 4 describes a multi-layer diaphragm for an acoustic transducer, for example. This acoustic transducer is at least from a sheet of plastic material and from which a spun fiber layer of natural or synthetic fiber or a burned material is under pressure and heating,
Collected in a uniform diaphragm. What is achieved thereby is that the adhesion of the damping layer made of conventionally used metal is improved, and thus the economic stability of the acoustic properties of the diaphragm is improved.

Austrian patent publication 286396 shows a diaphragm made of thermoplastic for electroacoustic transducers. In this case, wool fibers are applied to the surface of at least one diaphragm. The fibers can be formed from electrostatically deposited fibers or also from natural fibers. These fibers are then combined with the diaphragm during a pressing or drafting process-which produces the diaphragm. This bond can also be produced with a heat-sealable lacquer. The purpose of this coating is to increase the inner torso of the diaphragm without the mechanical drawbacks associated with paper diaphragms.

The subject matter of both of the above patent publications starts from a different problem setting and therefore reaches a further solution.

According to the invention, the vibrating element is covered by a layer of thin fibers. These fibers are only partially connected to each other and, in particular, as a result of the relative movement between them, and because of the air contained in the mesh, they are vibrated by the sway of the fluid during the mesh movement. It removes energy from the part and strongly dampens higher vibration modes.

The fibrous material plays a role only insofar as it should have a high modulus to the surface itself. A stable mechanical bond must be formed between the fibers. The purpose is to make the damping characteristics independent of the period of use and climatic ambient conditions. This bond is due to the curable adhesive layer on the strand
Alternatively, the production can be performed as follows. That is, by forming the fiber itself from a polymeric material that is adhesive above the maximum operating temperature of the transducer,
Can be implemented.

Next, an embodiment of the present invention will be described with reference to the drawings.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the acoustic characteristics of a conventional diaphragm. The dashed curve 1 shows the frequency dependence of the impedance of a conventional acoustic transducer measured in air. Curve 2 shows the same frequency dependence measured in vacuum. Horizontal frequency scale is 20Hz to 20kHz
It has a logarithmic scale up to z. The impedance is plotted on a linear scale whose absolute value is from 80 to 620 homes.

The fundamental resonance exists at about 120 Hz in air. This fundamental resonance has a peak of resonance of about 205 ohms and is significantly damped compared to a constant voltage value of 90 ohms; nevertheless a partial vibration appears at about 1700 Hz (3). . In curve 2 measured in vacuum, there are three resonances of high Q (4,5,6).

The measurement curves (7 and 8) of the coated diaphragm shown in FIG. 2 are otherwise the same as in FIG. 1, but are not shown with spurious resonances. For uncoated diaphragms, these curves have a maximum impedance of 3 at about 600 Hz in vacuum.
50 ohms, 16 in air at 200 Hz
Indicates 0 ohm.

FIG. 3 shows a scanning electron microscope image of the damping layer according to the invention. The figure clearly shows the irregularly formed fibers of polymeric material.

FIG. 4 shows a simplified view of the layer according to the invention in order to show its operation.

As shown, the threads 10, 11 are partially bonded to each other, and the points of contact 14 are partially with each other.
The mesh consisting of the threads 12, 13 which are only in contact with each other contributes to the damping of the diaphragm movement by means of a mechanical visor.

FIG. 5 shows a cross section of the diaphragm 15 partially covered by the damping layer 16 according to the invention.

FIG. 6 shows the damping layer 16. The damping layer is supported on the one hand on the vibration-damped vibration coil conductors 17 and on the other hand on the disc 18 on which the entire acoustic transducer is assembled. For clarity, FIG. 7 shows the section taken from line VIa in FIG.

FIG. 8 shows a cross sectional view of the transducer. The rear wall 19 of the transducer is covered with a layer 16 according to the invention, so that vibrations are damped.

[Brief description of drawings]

FIG. 1 is a diagram showing the frequency dependence of impedance of an electroacoustic transducer having a normal configuration measured in air and in vacuum.

FIG. 2 is a similar measurement curve diagram of the same transducer with a diaphragm coated according to the present invention.

FIG. 3 is a diagram of an example of a dressing according to the present invention.

FIG. 4 is an operation diagram of a covering material.

FIG. 5 is a diaphragm diagram with a damping layer.

FIG. 6 is an example of a conductor having a damping layer.

FIG. 7 is an example of a line with a damping layer.

FIG. 8 is a cross-sectional view of a transducer having a back wall with vibration damping.

[Explanation of symbols]

 12, 13 Fiber 14 Contact point 15 Diaphragm 16 Damping layer 17 Vibration coil conductor

Claims (6)

[Claims] 1. An electroacoustic transducer in which the vibrating parts (15, 17, 19) of the transducer are partly or wholly partly connected to one another by a layer of fibers (10, 11) and An electroacoustic transducer, characterized in that it is covered by a layer of fibers (12, 13) which are only partially in contact with each other. 2. A transducer as claimed in claim 1, characterized in that said layer (16) partially or totally covers the transducer diaphragm (15). 3. A transducer as claimed in claim 1, wherein the layer (16) partially or totally covers one or more moving coil connection lines (17) of the transducer. 4. The damping layer (16) is supported on the one hand on the oscillating coil connecting line (17) and on the other hand on the assembled disc (18) of the entire transducer. 3. The converter according to item 3. 5. The method according to claim 1, wherein the layer (16) partially or wholly covers one or more converter casing parts (19). Converter. 6. A transducer, wherein the layer (16) is formed from a strand of polymeric adhesive.