JP2009044584A - Voice coil for speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voice coil for a speaker, whose vibration is not inhibited by surrounding air in a low-frequency band. <P>SOLUTION: In the voice coil for a speaker, in which a coil 14 is wound around a voice coil bobbin 13 and the coil 14 is placed in a magnetic gap of a magnetic circuit, an outer peripheral surface of the voice coil bobbin 13 is provided with streamline-shaped portions 15, 16 that are smoothly lined with a front end edge or back end edge of the coil 14. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a speaker, and more particularly to the structure of the voice coil.

  An example of a conventional speaker will be described with reference to FIGS. FIG. 3 is a sectional view showing an example of a conventional speaker, and FIG. 4 is an enlarged view of a portion A in FIG. A frame 1 shown in the figure supports each member of the speaker, and a magnetic circuit 5 is fastened with a screw 11 at a central portion, and a peripheral edge of the diaphragm 2 is bonded and fixed through an edge 3 at a peripheral portion.

  As shown in detail in FIG. 4, the magnetic circuit 5 is formed by sequentially stacking and fixing a base 9, a magnet 6, a top plate 8, and a spacer 10 to the bottom surface of the bowl-shaped yoke 7. A neodymium magnet is used as the magnet 6. The yoke 7, the base 9, and the top plate 8 are magnetic materials, and the spacer 10 is a non-magnetic material.

  A magnetic gap 5 a is formed in the gap between the top plate 8 and the yoke 7. The magnetic circuit 5 is formed with a magnetic loop passing through the magnet 6, the top plate 8, the magnetic gap 5a, the yoke 7 and the base 9, and a magnetic field is generated in the magnetic gap 5a. The outer periphery of the voice coil bopin 13 is bonded to the inner periphery of the small diameter portion of the cone-shaped diaphragm 2, and the outer periphery of the damper 4 bonded to the outer periphery of the small diameter portion of the diaphragm 2 is bonded to the frame 1.

  As described above, the voice coil bopin 13 and the diaphragm 2 are supported by the frame 1 via the flexible edge 3 and the damper 4, but the magnetic circuit 5 is also supported by the frame 1. The bonding position of the edge 3 and the damper 4 is adjusted so that the coil 14 wound around the coil 14 is concentric with the annular magnetic gap 5a.

  When an audio signal current is supplied to the coil 14 in the magnetic field, the diaphragm 2 vibrates due to electromagnetic action, and audio corresponding to the audio signal current is emitted. The voice coil 12 formed by winding the coil 14 around the voice coil bopin 13 vibrates at a frequency of 20 to 20000 Hz, and its amplitude increases at a low frequency and becomes maximum at the lowest resonance frequency.

  By the way, in the conventional outer-magnet type speaker, the space between the yoke and the inner diameter of the magnet can be made relatively wide. However, like the magnetic circuit 5 described above, the inner-magnet type in which the magnet is arranged on the inner side of the voice coil. In a speaker using a magnetic circuit, the magnetic gap interval is small. On the other hand, in recent years, the demand for lightweight and thin speakers has increased, and an internal magnet type using a neodymium magnet is becoming mainstream as a magnetic circuit. In this case, the dimensional difference between the outer diameter of the magnet and the inner diameter of the yoke is reduced, and the voice coil is disposed in a narrow magnetic gap.

  For this reason, the air in the magnetic gap inhibits the vibration of the voice coil particularly in a low frequency region with a large amplitude. That is, the air and the voice coil move relative to each other. However, in the conventional voice coil, the resistance due to the collision between the air and the voice coil is large. FIG. 5 shows the air flow with respect to the voice coil by arrows. As shown in the figure, the air collides with the coil 14 wound around the voice coil bobbin 13 and the flow is disturbed. The resistance due to the turbulence of the air was large, and sufficient sound quality could not be obtained at low frequencies.

In the proposed magnetic circuit of the speaker proposed in Japanese Utility Model Laid-Open No. 61-103991, air holes are formed in the bottom surface of the yoke of the magnetic circuit. According to this configuration, it is possible to prevent the voice coil vibration from being inhibited by reducing the difference in the air pressure above and below the voice coil, but the difference in the air pressure above and below the voice coil is small. The degree of vibration inhibition of the voice coil due to was small and its effect was limited.
Japanese Utility Model Laid-Open No. 61-103991, specification, page 4, FIG. 1, FIG.

  The present invention has been made in view of the above points, and an object thereof is to provide a voice coil of a speaker in which vibration of the voice coil is not hindered by ambient air in a low frequency range.

  The voice coil of the speaker according to the present invention is a voice coil of a speaker in which a coil is wound around a voice coil bobbin and the coil is disposed in a magnetic gap of a magnetic circuit, and a leading edge or a trailing edge of the coil is disposed on an outer peripheral surface of the voice coil bobbin. A streamlined portion that is smoothly connected to each other is provided.

  In the voice coil of the speaker, dimples are formed on the inner peripheral surface of the voice coil bobbin.

  The voice coil of each speaker is arranged in a magnetic gab of an inner magnet type magnetic circuit using a rare earth magnet.

  According to the voice coil of the speaker of the present invention, since the vibration of the voice coil is not hindered by the surrounding air, the sound generation performance of the speaker is improved in the low frequency range.

  The best mode for carrying out the present invention will be described below with reference to examples. FIG. 1 is a partial sectional view showing a voice coil according to an embodiment of the present invention, and FIG. 2 is a view showing an air flow in the vicinity of the voice coil in the speaker.

  In the voice coil of the embodiment, a coil 14 is wound around the outer periphery of the voice coil bobbin 13, and a front streamline shape portion 15 and a rear streamline shape portion 16 are arranged in a state where the front end streamline shape portion 16 and the rear end streamline shape portion 16 are fixed to the voice coil bobbin 13. ing. The front streamline shape portion 15 and the rear streamline shape portion 16 have a substantially triangular cross section and are formed in a shape that is smoothly connected to the coil 14. The front streamline shape portion 15 and the rear streamline shape portion 16 may be formed integrally with the voice coil bobbin 13.

  A large number of dimples 13a, 13a... Are uniformly arranged on the inner surface of the voice coil bobbin 13. This voice coil is replaced with the voice coil 12 of the conventional speaker described in FIG. Other configurations are the same as those of the conventional speaker described in FIG.

  As shown in FIG. 2, the airflow near the voice coil tip flows smoothly along the surface of the coil 14 from the tip streamline-shaped portion 15, and no impact is generated by the collision. The rear end of the coil 14 also flows smoothly from the surface of the coil 14 along the rear end streamline-shaped portion 16, and the rear end of the coil 14 is not in a vacuum state. For this reason, the vibration of the voice coil is not inhibited by the airflow.

  Further, the dimples 13a, 13a,... On the inner surface of the voice coil bobbin 13 make the air flow on the inner surface of the voice coil bobbin 13 turbulent and reduce the large viscous resistance in the laminar flow, thereby reducing the force for suppressing the vibration of the voice coil. It is known that when the fluid flowing on the solid surface becomes a turbulent flow, the viscous resistance is reduced because the flight distance is greatly increased by providing dimples on the golf ball.

  As described above, the voice coil according to the embodiment provides an effect of enhancing the sound generation function in a low frequency region having a larger amplitude than that of the conventional voice coil.

  The embodiment is configured as described above, but the invention is not limited to this. For example, the streamline shape portion may be provided only at one of the front end and the rear end of the voice coil. Furthermore, the effect of the present invention can be obtained without providing dimples on the inner surface of the voice coil bobbin. Further, pores that communicate with the magnetic gab may be provided on the bottom surface of the yoke.

It is a fragmentary sectional view which shows the voice coil which is an Example of this invention. It is a fragmentary sectional view showing the air current near the voice coil in the speaker. It is sectional drawing which shows the example of the conventional speaker. It is the A section enlarged view in FIG. It is a figure which shows the air flow of the voice coil vicinity in the speaker.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Frame 2 Diaphragm 3 Edge 4 Damper 5 Magnetic circuit, 5a Magnetic gap 6 Magnet 7 Yoke 8 Top plate 9 Base 10 Spacer 11 Screw 12 Voice coil 13 Voice coil bobbin, 13a Dimple 14 Coil 15 Front streamline shape part 16 Rear end flow Line shape part

Claims (3)

In a voice coil of a speaker in which a coil is wound around a voice coil bobbin and the coil is disposed in a magnetic gap of a magnetic circuit, a streamline shape portion smoothly connected to a front edge or a rear edge of the coil is provided on an outer peripheral surface of the voice coil bobbin. A voice coil of a speaker characterized by being provided. 2. The voice coil according to claim 1, wherein dimples are formed on an inner peripheral surface of the voice coil bobbin. The voice coil according to claim 1 or 2, wherein the voice coil is disposed in a magnetic gap of an inner magnet type magnetic circuit using a rare earth magnet.

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