JP2011071612A - Electroacoustic transducer and method for manufacturing the same - Google Patents

Abstract

An electroacoustic transducer capable of setting the stiffness of a diaphragm as intended and without variations from excess adhesive from the edge of the outer periphery of the diaphragm, and its manufacture Get the way.
An outer peripheral edge portion of a diaphragm is fixed to a frame by adhesion. The frame 10 includes an adhesive inclined surface 103 that adheres the edge portion 205 on the outer periphery of the diaphragm 20, and the edge portion 205 of the diaphragm 20 has an inclination angle smaller than the inclination angle of the adhesive inclined surface 103 of the frame 10. Thus, a gap 104 formed between the edge portion 205 of the diaphragm 20 and the bonding inclined surface 103 of the frame 10 is filled with the adhesive 30.
[Selection] Figure 1

Description

  The present invention relates to an electroacoustic transducer such as a microphone and a speaker, and a method for manufacturing the same, and in particular, makes it possible to reduce the variation in stiffness of the diaphragm and make the acoustic characteristics uniform.

  A diaphragm is generally used in a microphone that receives a sound wave and converts it into an electric signal, and conversely, an electroacoustic transducer such as a speaker that converts an electric signal into a sound wave. In the microphone, the vibration of the diaphragm that vibrates in response to the sound wave is converted into an electric signal, and in the speaker, the diaphragm is vibrated by the electric signal to emit a sound wave.

  In the case of a dynamic electroacoustic transducer, a voice coil is integrally fixed to a diaphragm, a peripheral portion of the diaphragm is fixed to a frame or the like, and the voice coil is composed of a permanent magnet, a yoke, a pole piece, and the like. It is arranged in a magnetic gap in the magnetic circuit. In the case of a microphone, when the diaphragm receives a sound wave and vibrates together with the voice coil, the voice coil crosses the magnetic flux in the magnetic gap, thereby outputting a sound signal corresponding to the sound wave. In the case of a speaker, when a voice signal is input to the voice coil, the voice coil and the diaphragm are vibrated by the electromagnetic force of the current and the magnetic flux, and a sound wave corresponding to the voice signal is emitted.

  For example, a capacitor-type electroacoustic transducer has a diaphragm as well as a dynamic electroacoustic transducer. The peripheral portion of the diaphragm of the electroacoustic transducer is fixed to the frame or the like by bonding or the like, but is affected by acoustic characteristics such as a low frequency resonance frequency depending on the fixing condition of the peripheral portion of the diaphragm. In particular, the diaphragm used in a small speaker unit for microphones and headphones is a thin film molded product, and since the control method is a mass control method, the low-frequency limit for sound collection or reproduction is low. Determined by the resonance frequency of the region. The main components of the mass of the diaphragm are the voice coil, the diaphragm itself, and the additional mass of air that moves with the diaphragm. These mass components are determined by design and have little variation.

  On the other hand, the stiffness of the diaphragm varies depending on the molding conditions of the diaphragm, the adhesion state when the peripheral edge of the diaphragm is fixed to the frame, and the like. Hereinafter, these will be described more specifically. A diaphragm used for a small speaker unit for a microphone or a headphone is generally manufactured by heat and pressure molding, but the stiffness of each diaphragm varies depending on the thermal history of the material, various conditions during molding, and the like. In addition, the peripheral edge of the diaphragm is fixed to the unit frame by bonding as described above, but it varies depending on various factors such as the wettability of the adhesive, the shrinkage when drying the adhesive, and the stress applied during bonding. Variation in the stiffness of the diaphragm. When the stiffness varies, the low-frequency resonance frequency varies as described above.

  In particular, when trying to actively cancel out-of-target environmental noise, such as noise cancellation headphones, a cancellation signal is generated by inverting the phase of the environmental noise signal detected by the microphone. Although it is necessary to adjust the phase and amplitude appropriately, if the low-frequency resonance frequency of the microphone varies, it becomes a major factor for reducing the noise cancellation performance. Because the phase is reversed on the upper side (plus side) and the lower side (minus side) with the low frequency resonance frequency as a boundary, if the low frequency resonance frequency varies greatly, the audio frequency range that was not planned in the design This is because the phase is reversed in that region and the noise canceling effect is lost. In addition, if the low-frequency resonance frequency varies greatly between the left and right environmental noise detection microphones, the sound emitted from the left and right speakers (headphone drivers) differs, which causes a sense of discomfort to the user.

  Here, a specific example will be described by taking an example of a conventional electroacoustic transducer. FIG. 2 shows an example of an electroacoustic transducer configured as a headphone driver. In FIG. 2, the headphone driver is assembled on the basis of the unit frame 1. The unit frame 1 is a metal member having a circular outer shape, and a jetty 11 is formed on the outer peripheral edge of one surface over the entire circumference. On the formation surface side of the jetty 11, a jetty 12 lower than the height of the jetty 11 is formed over the entire circumference on the inner peripheral side of the jetty 11 and in the vicinity of the jetty 11. A cylindrical portion 13 is formed on the unit frame 1 so as to protrude from a surface opposite to the formation side of the jetty 11 and 12 along a circle concentric with the outer periphery thereof.

  A flat bottomed cylindrical yoke 2 is fitted on the inner periphery of the cylindrical portion 13 of the unit frame 1 with its open end facing the jetty 11 formation side, and is attached to the unit frame 1 by adhesion or press fitting. They are joined together. A disc-shaped permanent magnet 3 is fixed to the inner bottom surface of the yoke 2 between the outer peripheral surface and the inner surface of the peripheral wall of the yoke 2 at an appropriate interval. Further, a disk-shaped pole piece 4 is overlapped and fixed to the permanent magnet 3. An appropriate cylindrical gap is formed between the outer peripheral surface of the pole piece 4 and the inner surface of the peripheral wall of the yoke 2. A magnetic circuit is formed by the yoke 2, the permanent magnet 3, and the pole piece 4, and a magnetic flux passes from one of the pole piece 4 and the yoke 2 toward the other in the gap formed between the pole piece 4 and the yoke 2. It is a magnetic gap.

  In the magnetic gap, a voice coil 7 in which a thin conducting wire is wound in a cylindrical shape is arranged without contacting the yoke 2 and the pole piece 4. One end of the voice coil 7 is fixed to the diaphragm 5. The diaphragm 5 is formed of a thin film molded product, and has a main dome 51 in which a part of a spherical surface is cut off, and a sub dome 52 having a partially arcuate cross section integrally formed around the main dome 51. The outer peripheral side of the sub dome 52 is an edge portion that forms a flat surface. This edge portion is placed on the jetty 12 of the unit frame 1, and a protector 6 for protecting the diaphragm 5 is placed on the edge portion. More specifically, an edge portion 62 is formed on the outer periphery of the protector 6 so as to form a flat surface, and this edge portion 62 is placed on the edge portion of the diaphragm 5. The jetty 12 of the unit frame 1 and the edge part of the diaphragm 5, and the edge part and the edge part 62 of the protector 6 are bonded to each other so that the diaphragm 5 can vibrate using the edge part as a fulcrum. It has become. One end of the voice coil 7 is fixed along the ridgeline at the boundary between the main dome 51 and the sub dome 52 of the diaphragm 5.

  The protector 6 is formed in accordance with the shapes of the main dome 51 and the sub dome 52 of the diaphragm 5, and the edge is formed following the outer peripheral wall so that a certain space is formed between the main dome 51 and the sub dome 52. A portion 62 is formed. The protector 6 is formed with a plurality of holes 61 for emitting sound waves emitted by the vibration of the diaphragm 5 to the outside. A hole 14 is formed in the unit frame 1 for communicating the space on the back side of the diaphragm 5 to the outside so as not to be resistant to the vibration of the diaphragm 5. A plurality of holes 14 are formed, and an acoustic resistance material 8 is added to an appropriate hole 14 to adjust the acoustic characteristics of the headphone driver.

As described above, the example of the headphone driver has been described, but the diaphragm in the dynamic type microphone is also fixed to the flat surface of the unit frame by bonding the outer peripheral edge portion that forms a flat surface, similarly to the diaphragm 5.
In order to stabilize the characteristics of the electroacoustic transducer, it is necessary that the edge portion of the diaphragm is securely and firmly fixed to the unit frame. However, when the edge portion is fixed by adhesion, as shown by reference numeral 9 in FIG. 2, the surplus adhesive material protrudes from the vibration plate 5, and the protruding adhesive material is hardened to harden the vibration plate 5. When the diaphragm 5 becomes hard, it becomes difficult to vibrate, and the responsiveness particularly in the low sound range is deteriorated. In the case of a microphone, the low sound range is difficult to be converted into an electric signal, and in the case of a speaker, the low sound is difficult to be reproduced. In addition to this, since the amount of the protruding adhesive varies, there is also a problem that the characteristics vary in each electroacoustic transducer.

  As a conventional example of an electroacoustic transducer constructed as shown in FIG. 2, the electroacoustic transducer is configured in substantially the same manner as an electroacoustic transducer in which a flat edge portion on the outer periphery of a diaphragm is fixed to a flat surface of a frame by adhesion. There are inventions described. The electroacoustic transducer described in Patent Document 1 has the same technical problem as that described above because the diaphragm fixing structure is substantially the same as the fixing structure shown in FIG. ing.

JP 2004-64158 A

  The present invention eliminates the problems of the above-described conventional electroacoustic transducer, that is, although the edge portion of the outer periphery of the diaphragm is fixed by bonding, an extra adhesive is added to the vibration operation portion of the diaphragm. It is an object of the present invention to provide an electroacoustic transducer and a method for manufacturing the same that can set the stiffness of the diaphragm as expected without causing any protrusion.

  The present invention is an electroacoustic transducer in which an outer peripheral edge portion of a diaphragm is fixed to a frame by adhesion, and the frame includes an adhesion inclined surface for adhering the outer peripheral edge portion of the diaphragm, The edge portion of the diaphragm has an inclination angle smaller than the inclination angle of the bonding inclined surface of the frame, and a gap generated between the edge portion of the diaphragm and the bonding inclined surface of the frame is bonded. The main feature is that it is filled with chemicals.

  The present invention is also a method of manufacturing an electroacoustic transducer in which an edge portion on the outer periphery of a diaphragm is fixed to a frame by bonding, and the frame has an adhesive inclined surface for bonding the edge portion of the diaphragm. The edge portion of the diaphragm is pressed against the bonding inclined surface of the frame by a pressing jig, and a predetermined stress is applied to the edge portion of the diaphragm, and the edge portion of the diaphragm and the frame are bonded. A gap formed between the inclined surface and the inclined surface is filled with an adhesive and cured.

  According to the electroacoustic transducer of the present invention, the edge portion of the diaphragm has an inclination angle smaller than the inclination angle of the adhesion inclined surface of the frame, and the edge portion of the diaphragm and the adhesion inclined surface of the frame Since the gap formed between the two is filled with the adhesive, the adhesive stays in the gap and does not protrude into the vibrating portion of the diaphragm. Therefore, the sticking of the diaphragm does not become larger (harder) than expected with the protruding adhesive, and it is possible to obtain stable acoustic characteristics that are not particularly deteriorated in the low frequency range.

  According to the method for manufacturing an electroacoustic transducer according to the present invention, the edge portion of the diaphragm is pressed against the bonding inclined surface of the frame by a pressing jig, and a predetermined stress is applied to the edge portion of the diaphragm. Since the gap formed between the edge portion of the diaphragm and the bonding inclined surface of the frame is filled with an adhesive and cured, the stress applied to the edge portion of the diaphragm is stably maintained at a predetermined stress. The predetermined acoustic characteristics can be obtained without variation.

  If an adhesive that does not change its volume during the curing process or has a small volume change, such as an ultraviolet curable adhesive, can be used to set the diaphragm stiffness as intended. In addition, variation in stiffness can be reduced.

It is an expanded longitudinal cross-sectional view which shows the principal part of the Example of the electroacoustic transducer which concerns on this invention, and its manufacturing method. It is a longitudinal cross-sectional view which shows the example of the conventional electroacoustic transducer.

  An embodiment of an electroacoustic transducer according to the present invention and a manufacturing method thereof will be described below with reference to FIG.

  In FIG. 1, the code | symbol 10 has shown the flame | frame of the electroacoustic transducer. As in the conventional unit frame 1 shown in FIG. 1, the frame 10 has a circular outer periphery and integrally includes a cylindrical portion concentric with the outer periphery. As in the conventional example shown in FIG. 2, a cylindrical yoke with a bottom is fitted and fixed to the cylindrical portion, a permanent magnet is fixed to the yoke, and a pole piece is fixed to the permanent magnet. A magnetic circuit similar to the conventional example shown in FIG. 2 is configured. A cylindrical magnetic gap is formed between the pole piece and the yoke, and a voice coil (shown in the figure) is formed by winding a thin conducting wire into a cylindrical shape and fixing one end to the diaphragm 20 in the magnetic gap. Not) is located.

  As in the conventional example shown in FIG. 2, the diaphragm 20 is formed of a thin film molded product, and a main dome having a shape obtained by cutting off a part of a spherical surface, and a cross section integrally formed around the main dome are partially formed. An arc-shaped sub dome is provided, and an outer peripheral side of the sub dome is an edge portion 205. One end of the voice coil is fixed along the boundary between the main dome and the sub dome of the diaphragm. The edge portion 205 of the diaphragm is originally a flat surface. The edge portion forming the original flat surface is indicated by reference numeral 205A in FIG.

  A cylindrical jetty 101 is integrally formed on one surface side of the outer peripheral edge of the frame 10, and a jetty 102 lower than the jetty 101 is formed adjacent to the inner peripheral side of the jetty 101. The upper surface of the jetty 102 in FIG. 1 is an inclined surface whose height continuously decreases from the inner diameter side to the outer diameter side of the frame 10 in the longitudinal section of the frame 10. Since the edge portion 205 of the diaphragm 20 is bonded to the inclined surface with the adhesive 30, the inclined surface is referred to as an adhesive inclined surface 103. Since this adhesion inclined surface 103 is formed continuously in the circumferential direction of the frame 10, it forms a conical surface.

  As described above, the edge portion 205 of the diaphragm is originally a flat edge portion 205A. Therefore, when the flat edge portion 205 is placed on the jetty 102 of the frame 10, the base end portion of the edge portion 205 and one end portion of the bonding inclined surface 103 of the frame 10, that is, the uppermost end of the bonding inclined surface 103 and the jetty The contact 40 is in contact with the upper end of 102. Precisely, since the contact point 40 is continuous in the circumferential direction of the frame 10 and the diaphragm 20, it becomes a circular tangent. A gap 104 is formed on the outer peripheral side of the edge portion 205 of the diaphragm 20 and the bonding inclined surface 103 of the frame 10 rather than the contact point 40. The gap 104 is filled with the adhesive 30, and the edge portion 205 of the diaphragm 20 is fixed to the adhesive inclined surface 103 of the frame 10 by the adhesive 30 being cured.

  However, before the gap 104 is filled with the adhesive 30, as shown in FIG. 1, the flat edge portion 205A of the diaphragm 20 is pressed toward the bonding inclined surface 103 of the frame 10 by the cylindrical pressing jig 35, A predetermined stress is applied to the edge portion 205 of the diaphragm 20 to adjust the stiffness of the sub dome of the diaphragm 20 to a predetermined value. For example, whether or not the stiffness of the sub dome has reached a predetermined value is determined by applying a sound wave having a predetermined frequency to the diaphragm 20 or inputting an audio signal having a predetermined frequency to the voice coil. It can be performed by a method of oscillating at the predetermined frequency and observing it by irradiating it with strobe light. If the emission frequency of the strobe light is set to the predetermined frequency, the diaphragm 20 appears to stop when it vibrates at the predetermined frequency. At this time, the stiffness of the sub dome becomes a predetermined value. ing. In this state, the edge portion 205 of the diaphragm 20 is bonded as described later. If the emission frequency of the strobe light is gradually changed, the maximum movement position of the diaphragm 20 to the front side and the rear side can be observed, and therefore the amplitude of the diaphragm 20 can also be observed. In FIG. 1, a dotted line represents a state where the pressing jig 35 presses the edge portion 205 of the diaphragm 20. In this state, the edge portion 205 of the diaphragm 20 uses the contact point 40 as a fulcrum. The flexure is approaching the bonding inclined surface 103 of the frame 10.

  The edge portion 205 of the diaphragm 20 forms a conical surface by bending the entire circumference at the same angle with the contact point 40 as a fulcrum. The inclination angle of the edge portion 205 of the vibration plate 20 is smaller than the inclination angle of the bonding inclined surface 103 of the frame 10, and a predetermined stress is applied to the edge portion 205 of the vibration plate 20. In this state, the adhesive 30 is applied to the gap 104 formed between the edge portion 205 of the diaphragm 20 and the bonding inclined surface 103 of the frame 10 to fill the gap 104, and the adhesive 30 is cured to vibrate. The edge portion 205 of the plate 20 is bonded to the bonding inclined surface 103 of the frame 10.

  It is preferable that the adhesive 30 has no volume shrinkage during the curing process or has as little volume shrinkage as possible. For example, an ultraviolet curable adhesive or RTV rubber used as a sealant may be used. In particular, since the ultraviolet curable adhesive has almost no volume shrinkage, when the edge portion 205 of the diaphragm 20 is bonded with a predetermined stress applied, the above-mentioned stress fluctuates due to the hardening of the adhesive. Absent. Further, since the ultraviolet curable adhesive is cured by irradiating with ultraviolet rays, there is an advantage that the curing process can be arbitrarily controlled.

  In the case of using an ultraviolet curable adhesive, the diaphragm 20 is made of a transparent, for example, plastic film so that the ultraviolet rays for curing the adhesive 30 can be transmitted. After fixing the diaphragm 20 to the frame 10 as described above, the pressing jig 35 is removed, and a protector is disposed at a predetermined interval between the diaphragm 20 and covering the diaphragm 20, and this is attached to the frame. 10 is fixed.

  The adhesive applied to the gap 104 formed between the edge portion 205 of the diaphragm 20 and the bonding inclined surface 103 of the frame 10 is held in the gap 104 by surface tension and is applied to the vibrating portion of the diaphragm 20 and the like. There is almost no flow. Therefore, after the predetermined stress is applied to the edge portion 205 of the diaphragm 20 to set the stiffness of the diaphragm 20 to a predetermined value, there is no problem that the stiffness varies depending on the adhesive. In particular, it is possible to avoid the occurrence of a problem that the adhesive protrudes from the vibration portion of the diaphragm, the stiffness of the diaphragm becomes larger than expected, and the responsiveness in the low sound range is lowered. In addition, the acoustic characteristics do not vary.

The electroacoustic transducer and the manufacturing method thereof according to the present invention can be applied as a microphone unit and a manufacturing method thereof, or as a speaker unit and a manufacturing method thereof.
The bonding inclined surface 103 may not be a continuous inclined surface as in the illustrated embodiment, and may be an inclined surface whose height changes stepwise, for example.

  The electroacoustic transducer according to the present invention is suitable as a microphone for detecting environmental noise in a noise canceling headphone. That is, since there is little variation in the low-frequency resonance frequency, it has an adverse effect on the above-described noise cancellation caused by the large variation in the low-frequency resonance frequency, and the left-right noise cancellation effect varies greatly. This is because an uncomfortable feeling can be avoided.

DESCRIPTION OF SYMBOLS 10 Frame 20 Diaphragm 30 Adhesive 35 Pressing jig 40 Contact 103 Bonding inclined surface 104 Gap 205 Edge part

Claims (8)

An electroacoustic transducer in which the edge of the outer periphery of the diaphragm is fixed to the frame by bonding,
The frame includes an adhesion inclined surface for adhering an edge portion on the outer periphery of the diaphragm,
The edge portion of the diaphragm has an inclination angle smaller than the inclination angle of the adhesion inclined surface of the frame,
An electroacoustic transducer in which a gap formed between an edge portion of the diaphragm and an adhesion inclined surface of the frame is filled with an adhesive.   The electroacoustic transducer according to claim 1, wherein both the edge portion of the diaphragm and the bonding inclined surface of the frame are conical surfaces.   The electroacoustic transducer according to claim 1 or 2, wherein the adhesive is an ultraviolet curable adhesive.   The base end portion of the edge portion of the diaphragm and one end portion of the bonding inclined surface of the frame are contact points, and there is a gap on the outer peripheral side of the edge portion of the diaphragm and the bonding inclined surface of the frame from this contact point. The electroacoustic transducer according to claim 1, 2 or 3, wherein the gap is filled with an adhesive.   In a state where a predetermined stress is applied to the diaphragm due to the edge portion of the diaphragm being pushed toward the bonding inclined surface of the frame, the edge portion of the diaphragm and the bonding inclined surface of the frame are between The electroacoustic transducer according to any one of claims 1 to 4, wherein a gap formed in the substrate is filled with an adhesive. A method of manufacturing an electroacoustic transducer in which an outer peripheral edge portion of a diaphragm is fixed to a frame by adhesion,
The frame is provided with a bonding inclined surface for bonding the edge portion of the diaphragm,
Press the edge part of the diaphragm toward the bonding inclined surface of the frame by a pressing jig,
Manufacture of an electroacoustic transducer in which a gap formed between the edge portion of the diaphragm and the inclined inclined surface of the frame is filled with an adhesive and cured with a predetermined stress applied to the edge portion of the diaphragm Method.   The method for manufacturing an electroacoustic transducer according to claim 6, wherein both the edge portion of the diaphragm and the bonding inclined surface of the frame are conical surfaces.   The method for producing an electroacoustic transducer according to claim 6 or 7, wherein an ultraviolet curable adhesive is used as the adhesive.

Images