JP6333547B2 - Diaphragm, manufacturing method thereof, and electrodynamic electroacoustic transducer - Google Patents

Description

  The present invention relates to a diaphragm used in an electrodynamic electroacoustic transducer. More specifically, the present invention can reliably prevent resonance of the diaphragm in the audible frequency band and can easily adjust the stiffness of the vibration system. It is about technology.

  The electrodynamic electroacoustic transducer includes a dynamic microphone unit and a dynamic headphone unit. Since the basic configuration is common, FIG. 4 shows a schematic configuration of the dynamic headphone unit. This will be described.

  The dynamic headphone unit includes a diaphragm 10, a magnetic circuit unit 20, and a unit frame 30 as a basic configuration.

  The diaphragm 10 is usually made of a single synthetic resin film, and has a center dome 11 having a dome shape and a sub dome 12 having a dome shape around the dome shape, and a boundary between the center dome 11 and the sub dome 12. On the back side of the part, the movable wire ring 13 is integrally attached with an adhesive. The sub dome is sometimes called an edge portion, and the movable wire ring is sometimes called a voice coil.

  The magnetic circuit unit 20 includes a plate-shaped yoke 21 whose peripheral portion 21 a is raised substantially at a right angle, a disk-shaped magnet 22 provided at the center of the bottom of the yoke 21, and a pole piece disposed on the magnet 22. (Magnetic pole) 23. The magnet 22 is magnetized in the plate thickness direction, whereby a magnetic gap G is formed between the pole piece 23 and the peripheral portion 21 a of the yoke 21.

  The unit frame 30 is formed of a disc-like support body that fits and holds the magnetic circuit unit 20 at the center portion, and the diaphragm 10 has an end of the sub dome 12 so that the movable wire ring 13 is located in the magnetic gap G. The portion is supported by the peripheral portion of the flange portion 31 of the unit frame 30 whose diameter has been increased. A protector 40 made of punching metal or the like is attached to the unit frame 30 so as to cover the front side of the diaphragm 10.

  In the headphone unit, a drive current based on an audio signal is passed through the movable wire ring 13, thereby vibrating the diaphragm 10 and emitting sound waves. On the other hand, in the microphone unit, the diaphragm 10 is vibrated by the incoming sound wave, whereby a current is generated in the movable wire ring 13 and an audio signal is output.

  In any case, the center dome 11 is required not to be easily deformed even when a driving force from the movable wire ring 13 or an external sound wave is applied. One countermeasure is to increase the mechanical strength by stacking two films, for example.

  On the other hand, the sub dome 12 functions as a portion that imparts stiffness to the diaphragm 10. The stiffness of the subdome 12 is designed so that the diaphragm 10 vibrates at a target resonance frequency.

  Since the center dome 11 and the sub dome 12 are both formed in a dome shape, air chambers A1 and A2 are formed between the center dome 11 and the pole piece 23 and between the sub dome 12 and the unit frame 30, respectively. .

  These air chambers A1 and A2 operate as acoustic capacitances (air springs, which are represented by an electrostatic capacity component C in an equivalent circuit), and this acoustic capacitance is the acoustic mass (equivalent circuit-like) in the magnetic gap G. Is represented by an inductance component L).

  If this resonance frequency is in a band where sound is emitted from the headphone unit or in a band where sound is picked up by the microphone unit, the frequency response and directivity are degraded. In order to prevent this, the co-frequency of the acoustic capacity and the acoustic mass should be higher than the audible frequency handled.

  For this purpose, it is necessary to make the volumes of the air chambers A1 and A2 as small as possible. As one of the methods, there is known a method of providing convex lens-like attachment members 51 and 52 similar to the dome shape on the pole piece 23 side and the unit frame 30 side as shown in FIG. , See Patent Document 1).

Japanese Utility Model Publication No. 61-182195

  However, using an attachment member as a separate member naturally increases the cost accordingly. In addition, even if the attachment member is formed into a convex curved surface shape according to the dome shape, the dome shape on the diaphragm side varies due to heat shrinkage of the film, etc., so the volume of the air chamber is reduced by the attachment member. However, it is difficult to uniformize the air chamber capacity for each product. This means that the resonance frequency varies for each product.

  As another problem, in the above prior art, a predetermined stiffness is imparted to the diaphragm by the sub dome, but it is difficult to adjust the diaphragm. That is, since the sub dome is press-molded with a single synthetic resin film integrally with the center dome, in order to adjust or change the stiffness of the sub dome, the molding die itself must be reworked. And take time.

  Furthermore, a biaxially stretched film is usually used as a synthetic resin film for forming a diaphragm. However, when stress is applied to the subdome (edge portion), the mechanical properties of the film are different in the vertical and horizontal directions. Due to the difference, the center dome is distorted, and the bonded part of the movable wire ring (voice coil) may not be circular.

  Therefore, an object of the present invention is to reduce the volume of the air chamber on the back side of the diaphragm included in the setting element of the resonance frequency of the diaphragm without any variation for each product, and to reduce the stiffness of the edge portion. An object of the present invention is to provide a diaphragm that can be adjusted easily and a method for manufacturing the diaphragm.

In order to solve the above-described problems, a diaphragm according to the present invention has a diaphragm base made of a thermoplastic synthetic resin film supported by a diaphragm ring, and a magnetic circuit portion is formed on one surface of the diaphragm base. In the diaphragm provided with the movable wire ring disposed in the magnetic gap,
A circular flat plate having rigidity that can be displaced as a flat plate is integrally and coaxially joined to the diaphragm base, and the outer periphery of the flat plate and the inside of the diaphragm ring An edge portion formed by three-dimensionally molding the diaphragm base material is formed between the periphery and the diaphragm ring is a part of the outer peripheral side of the edge portion in a state where a predetermined tension is applied to the edge portion. Is attached to the periphery of the diaphragm base material, and the movable wire ring is provided in a portion where the flat plate is present.

  In the present invention, the flat plate may be a metal material or a synthetic resin material, but is particularly preferably a carbon material.

  In addition, as the three-dimensional pattern formed on the edge portion, a mixed pattern including a second concavo-convex pattern having a short period and a fine concavo-convex pattern in the first concavo-convex pattern having a long period is preferably employed. .

  The present invention includes a method for manufacturing a diaphragm. The manufacturing method of the present invention includes a diaphragm base material made of a thermoplastic synthetic resin film supported by a diaphragm ring. In the manufacturing method of a diaphragm, in which a movable wire ring disposed in the magnetic gap of the magnetic circuit portion is provided on the surface of the diaphragm, the diaphragm base material is attached to a jig ring having a diameter larger than that of the diaphragm ring. A first step, a second step of attaching a circular flat plate having rigidity that can be displaced as a flat plate to the central portion of the diaphragm base member, and a coaxial plate with the jig ring; and A third step of forming an edge portion around in a three-dimensional pattern, and a range from the flat plate body to at least a part of the edge portion is placed on a cylindrical anvil jig having a flat upper surface, and the anvil The above jig jig is removed from the jig. A fourth step of adjusting the stiffness of the edge portion by applying a predetermined weight to the groove, a fifth step of adhering the diaphragm ring to the peripheral portion of the diaphragm base, and the portion where the flat plate is present And a sixth step of mounting the movable wire ring.

  In the method for manufacturing a diaphragm according to the present invention, the second step may be executed after the third step or after the fourth step.

  Further, in the third step, it is preferable that the edge portion is formed in a mixed pattern including a second concavo-convex pattern having a short period and a fine concavo-convex pattern in a first concavo-convex pattern having a long period.

  Further, in the fifth step, when the diaphragm ring is bonded to the peripheral edge portion of the diaphragm base material, a part of the outer peripheral side of the edge portion can be included in the bonded portion.

  Furthermore, the present invention includes the above-described diaphragm (including the diaphragm manufactured by the above-described manufacturing method) and a magnetic circuit unit having a magnetic gap in which the movable wire ring provided on the diaphragm is disposed. Also included are electrodynamic electroacoustic transducers for headphone units or microphone units.

  According to the present invention, a circular flat plate having rigidity that can be displaced as a flat plate is integrally joined to a central portion (a portion corresponding to a conventional center dome or a portion wider than the central dome) of the diaphragm so as to cause planar vibration. By adopting a plate, the volume of the air chamber existing on the back side of the diaphragm can be made smaller and uniform without any variation from product to product compared to the conventional dome shape, and the resonance frequency of the diaphragm Can be reliably set outside the audible frequency band.

  Further, the stiffness of the edge portion can be easily adjusted by the tension applied to the three-dimensionally formed edge portion (the tension applied along the radial direction of the diaphragm).

1 is a schematic cross-sectional view showing an electrodynamic electroacoustic transducer provided with a diaphragm according to an embodiment of the present invention. The expanded sectional view which shows the three-dimensional pattern formed in the edge part of the said diaphragm. (A)-(d) The schematic diagram which shows the manufacturing process of the diaphragm by this invention. Schematic sectional drawing which shows the structure of the conventional general electrodynamic electroacoustic transducer. FIG. 6 is a schematic cross-sectional view showing a configuration of a conventional electrodynamic electroacoustic transducer having means for reducing the volume of the air chamber on the back side of the diaphragm.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 3, but the present invention is not limited to this. In the embodiment described here, the same reference numerals are assigned to components that do not need to be changed from the conventional example of FIG. 4 described above.

  Referring to FIG. 1, the electrodynamic electroacoustic transducer according to this embodiment is a dynamic headphone unit. As a basic configuration, diaphragm 10A, magnetic circuit unit 20, unit frame 30, and protector 40 are provided. And.

  The magnetic circuit unit 20 and the unit frame 30 may be the same as the conventional example of FIG. 4 described above, and the magnetic circuit unit 20 includes a plate-like yoke 21 with a peripheral portion 21a raised substantially at a right angle. , A disc-shaped magnet 22 provided at the bottom center portion of the yoke 21, and a pole piece (magnetic pole) 23 disposed on the magnet 22.

  The magnet 22 is magnetized in the plate thickness direction, whereby a magnetic gap G is formed between the pole piece 23 and the peripheral portion 21 a of the yoke 21.

  Further, the unit frame 30 has a flange portion 31 with an enlarged diameter, and is formed of a disk-like support body that fits and holds the magnetic circuit portion 20 at the center portion. The diaphragm 10A is supported by the peripheral portion of the flange portion 31 so as to be able to vibrate, and a protector 40 made of a punching metal or a metal net is provided on the peripheral portion of the flange portion 31 so as to cover the front surface of the diaphragm 10A. It is attached.

  In this embodiment, the diaphragm 10 </ b> A is formed in a planar shape as a planar diaphragm formed by integrally joining a circular flat plate 120 having a predetermined rigidity at a central portion of the diaphragm base 110. Accordingly, the protector 40 is also formed in a circular flat dish shape.

  The diaphragm base 110 is made of a thermoplastic synthetic resin film. In this embodiment, a PET (polyethylene terephthalate) film is used. For the headphone unit, the thickness may be about 50 μm, and for the microphone unit, the thickness may be about 9-16 μm.

  The material of the flat plate 120 may be a metal material, a hard synthetic resin material, a carbon material, or the like as long as it has rigidity capable of being displaced as a flat plate, but it is lightweight and has a radial direction with respect to the diaphragm base 110. A carbon material (carbon plate) that is not easily deformed even when stress is applied to is preferable.

  Around the flat body 120, an edge portion 130 having a predetermined stiffness is formed, which is formed of a three-dimensional uneven pattern. The uneven pattern of the edge portion 130 may be a wave shape or a zigzag shape, but is preferably a mixed pattern 131 as shown in FIG.

  The mixed pattern 131 is a pattern that is unlikely to have a natural resonance including a second concavo-convex pattern 133 having a fine concavo-convex having a short period T2 (<T1) in a first concavo-convex pattern 132 having a rough concavoconvex having a long period T1. .

  The diaphragm 10 </ b> A has an outer peripheral edge attached to a diaphragm ring (membrane support ring) 140 in a state where a predetermined tension is applied to the edge portion 130. The diaphragm ring 140 is supported on the peripheral edge portion of the flange portion 31 of the unit frame 30.

  In addition, since the movable wire ring 13 arrange | positioned in the magnetic gap G is attached to the back surface side of the flat plate body 120, the flat plate body 120 is beyond the outer diameter of the movable wire ring 13, and is a required edge. As long as the region of the portion 130 is not damaged, it is preferable that the diameter of the unit frame 30 is as large as possible as shown in FIG.

  According to this, since the portion of the flat plate 120 occupying most of the diaphragm 10A is a flat surface, between the diaphragm 10A and the pole piece 23, between the diaphragm 10A and the unit frame 30, It is only necessary to provide a gap that exceeds the maximum displacement of the diaphragm 10A, and the volume of the air chamber existing on the back surface side of the diaphragm 10A can be reduced as much as possible. In addition, since the gap can be set almost uniformly for each product (headphone unit or microphone unit), the resonance frequency of the diaphragm 10A can be reliably set outside the audible frequency band.

  In the present invention, the stiffness can be adjusted by the tension applied to the edge portion 130. An example of a method for manufacturing a diaphragm including this point will be described with reference to FIG.

  First, as a first step, as shown in FIG. 3A (the left figure is a plane and the right figure is a cross section), the diaphragm base material (hereinafter referred to as “PET film”) 110 has a larger diameter than the diaphragm ring 140. Then, as a second step, a circular flat plate (hereinafter referred to as “carbon plate”) 120 is coaxially attached to the jig ring 150 as a second step. Thus, the temporary diaphragm assembly 101 is obtained.

  Then, as a third step, an edge portion 130 made of a three-dimensional uneven pattern is formed around the carbon plate 120. For this, as shown in FIG. 3B, a molding die 160 and a pressure pot 170 are used.

  The upper surface of the molding die 160 has a flat central portion on which the carbon plate 120 is placed, and a predetermined uneven pattern (in the present embodiment, the mixed pattern 131 described above) is formed around the edge portion 130. A pattern shaping portion 161 is engraved. Further, the molding die 160 is provided with a heating means made of, for example, an electric heater, and a water-cooling type cooling means (both not shown), for example.

  The pressurizing pot 170 can be moved up and down by an elevating means (not shown) such as an air cylinder, and includes a pressurized air supply port 171 connected to an air compressor (not shown).

  The temporary diaphragm assembly 101 is placed on the molding die 160, and the electric heater is energized to raise the molding die 160 to a temperature at which the PET film 110 can be molded, thereby softening the PET film 110.

  Thereafter, with the pressure pot 170 lowered and in close contact with the jig ring 150, the air compressor is started and pressurized air is introduced into the pressure pot 170 from the pressurized air supply port 171. The film 110 is pressed against the pattern shaping portion 161.

  After a predetermined time, the power supply to the electric heater is turned off, and this time, the cooling mold is used to cool the molding die 160 to a predetermined temperature, the air compressor is stopped, and the pressure pot 170 is raised, The temporary diaphragm assembly 101 is removed from the molding die 160.

  Thus, after forming the mixed pattern 131 in the edge part 130, the stiffness of the edge part 130 is adjusted as a 4th process. For this, an anvil jig 180 shown in FIG. The anvil jig 180 is a cylindrical body having a flat upper surface and an outer diameter smaller than the inner diameter of the jig ring 150.

  On the anvil jig 180, as shown in FIG. 3 (c), a range from the carbon plate 120 to at least a part of the edge portion 130 is placed, removed from the anvil jig 180, and a jig positioned outside thereof. A weight 190 having a predetermined weight is put on the ring 150 for use. Thereby, the edge part 130 extends in the radial direction in accordance with the weight of the weight 190, and the stiffness thereof is adjusted.

  Thereafter, as a fifth step, the diaphragm ring 140 is bonded to the peripheral portion of the PET film 110 via an adhesive. At that time, a part on the outer peripheral side of the mixed uneven pattern 131 formed on the edge portion 130 may be included in the portion bonded to the diaphragm ring 140.

  Then, as the sixth step (final step), as shown in FIG. 3D, the PET film 110 protruding from the diaphragm ring 140 is cut off with a cutter or the like, and the movable wire ring 13 is bonded to the back side of the carbon plate 120. Attach them together with materials.

  Thus, according to the present invention, the diaphragm 10A in which the stiffness of the edge portion 130 is appropriately adjusted according to the weight of the weight 190 is obtained, but the uneven pattern to be formed on the edge portion 130 is formed into a wave shape and a zigzag shape. It is good also as a shape.

  At this time, since the carbon plate that does not easily deform even when stress is applied in the radial direction is adopted as the circular flat plate 120, the edge portion 130 can be formed while maintaining the bonded portion of the movable wire ring 13 in a circular shape. it can.

  Further, the second step (the step of attaching the carbon plate 120) is continued after the mixed uneven pattern 131 is formed on the edge portion 130 in the third step, or after the stiffness of the edge portion 130 is adjusted in the fourth step. You may go.

DESCRIPTION OF SYMBOLS 10A Diaphragm 110 Diaphragm base material 120 Flat body 130 Edge part 131 Mixed uneven | corrugated pattern 140 Diaphragm ring 150 Jig ring 160 Molding die 161 Pattern shaping part 170 Pressure pot 180 Anvil jig 190 Weight 13 Movable wire ring 20 Magnetic circuit part 21 Yoke 22 Magnet 23 Pole piece 30 Unit frame 31 Flange part 40 Protector G Magnetic gap

Claims (8)

A diaphragm base material made of a thermoplastic synthetic resin film supported by a diaphragm ring is provided, and a movable wire ring disposed in a magnetic gap of the magnetic circuit portion is provided on one surface of the diaphragm base material. In the diaphragm that
A circular flat plate having rigidity that can be displaced as a flat plate is integrally and coaxially joined to the diaphragm base, and the outer periphery of the flat plate and the inside of the diaphragm ring An edge portion formed by three-dimensionally molding the diaphragm base material is formed between the periphery and the diaphragm ring is a part of the outer peripheral side of the edge portion in a state where a predetermined tension is applied to the edge portion. The diaphragm is bonded to a peripheral portion of the diaphragm base so as to include the movable wire ring, and the movable wire ring is provided in a portion where the flat plate is present.   The diaphragm according to claim 1, wherein the flat plate is made of a carbon material.   The said edge part is formed in the 1st uneven | corrugated pattern which consists of a rough unevenness | corrugation with a long period by the mixed pattern containing the 2nd uneven | corrugated pattern which consists of a fine unevenness | corrugation with a short period. Diaphragm. A diaphragm base material made of a thermoplastic synthetic resin film supported by a diaphragm ring is provided, and a movable wire ring disposed in a magnetic gap of the magnetic circuit portion is provided on one surface of the diaphragm base material. In the manufacturing method of a diaphragm,
A first step of attaching the diaphragm base material to a jig ring having a diameter larger than that of the diaphragm ring;
A second step of attaching a circular flat plate having rigidity that can be displaced as a flat plate to the central portion of the diaphragm base material, coaxially with the jig ring;
A third step of forming an edge portion around the flat plate in a three-dimensional pattern;
The range from the flat plate to at least a part of the edge portion is placed on a cylindrical anvil jig having a flat upper surface, and a predetermined weight is applied to the jig ring removed from the anvil jig. A fourth step of adjusting the stiffness of the edge part;
A fifth step of bonding the diaphragm ring to the peripheral edge of the diaphragm base;
And a sixth step of attaching the movable wire ring to a portion where the flat plate is present. 5. The method for manufacturing a diaphragm according to claim 4 , wherein the second step is continuously executed after the third step or after the fourth step. 6. In the third step, claim characterized by forming a mixed pattern including a second concave-convex pattern consisting of short fine irregularities periodicity in a first concavo-convex pattern in comprising the edge portion of the long coarse irregularities cycle 4 Or the manufacturing method of the diaphragm of 5 . In the fifth step, when bonding the diaphragm ring on the periphery of the diaphragm base, any of claims 4 to 6, characterized in that to include a portion of the outer peripheral side of the edge portion on the adhesive portion A method for manufacturing the diaphragm according to claim 1. A diaphragm manufactured by the diaphragm according to claim 1 or the manufacturing method according to claim 4 , and a magnetic circuit section having a magnetic gap in which the movable wire ring provided on the diaphragm is disposed. An electrodynamic electroacoustic transducer characterized by

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