JP2017092704A - Headphone unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a headphone unit capable of adjusting a sharpness according to a tone quality preference of a listener.SOLUTION: A headphone unit 100 includes a diaphragm 10, a unit frame 30, and an edge support portion 50. The unit frame has an edge support portion, and an edge portion 11 formed on the outer edge portion of the vibration plate is supported by the frame via the edge support portion. The edge support portion has a stiffness varying body 51, a variator holding section (a ring magnet 52, a front yoke 54 and a rear yoke 55), and a variator characteristic changing section (a coil 53). The stiffness changing body is a material which reversibly changes its characteristics between a free fluid and a semisolid in accordance with the strength of externally applied energy. The variator holding portion holds the stiffness changing body so as to remain around the edge portion. The variator characteristic changing section generates energy to be applied to the stiffness change body.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a headphone unit.

  A generally known headphone unit includes an electroacoustic transducer. As the electroacoustic transducer, a dynamic type and a capacitor type are known. The dynamic electroacoustic transducer has a basic configuration including a diaphragm, a magnetic circuit unit, and a unit frame. The electroacoustic transducer can also be applied to a microphone.

  A normal diaphragm is produced from a single synthetic resin film. A center dome is formed at the center of one synthetic resin film, and a sub dome is formed around the center dome. When the top of the center dome and the sub dome is the front side of the diaphragm, a voice coil is fixed to the boundary between the center dome and the sub dome on the back side of the diaphragm. An adhesive or the like is used for fixing the voice coil to the diaphragm. In the following description, the front side of the diaphragm may be referred to as the front, and the back side of the diaphragm may be referred to as the rear.

  The magnetic circuit unit included in the dynamic headphone unit includes a dish-shaped yoke, a disk-shaped magnet disposed in the center of a portion corresponding to the bottom of the yoke, and a pole piece disposed on the magnet. This magnet is magnetized in the thickness direction. Generally, the shape of the yoke and the pole piece viewed from the front is circular. The pole piece is arranged inside the yoke. A gap is formed between the outer peripheral wall of the pole piece and the inner peripheral wall of the yoke. This gap is a magnetic gap in which a magnetic field is generated by a magnet.

  The unit frame included in the dynamic headphone unit is a disk-like support that holds the magnetic circuit unit at the center. The unit frame has a flange portion formed by expanding the outer peripheral wall of the central portion. The unit frame is fixed in a state where the voice coil fixed to the diaphragm is disposed in the magnetic gap. Therefore, the end portion of the sub dome of the diaphragm is supported by the peripheral portion of the flange portion. A protector for covering and protecting the front of the diaphragm is attached to the unit frame.

  When an electric signal is supplied to the voice coil, this becomes a drive current and the diaphragm vibrates. Sound waves are emitted by the vibration of the diaphragm. The center dome is required not to be easily deformed during vibration. The sub dome functions as a portion that gives stiffness to the diaphragm. The resonance frequency of the diaphragm changes due to the stiffness of the subdome. The stiffness of the sub dome is adjusted so that the resonance frequency of the diaphragm becomes a design target frequency.

  The center dome and the sub dome are both dome-shaped. Therefore, a space is formed between the center dome and the pole piece, or between the sub dome and the unit frame. That is, a space called an air chamber is formed behind the center dome and the sub dome. The air chamber operates as an acoustic capacity that affects the acoustic characteristics of the dynamic headphone unit. Both the acoustic capacity of the air chamber and the acoustic mass of the magnetic gap are factors that cause resonance in the diaphragm at a predetermined frequency. The acoustic capacity is an air spring and can be expressed by an electrostatic capacity component in terms of an equivalent circuit. The acoustic mass can be expressed by an inductance component in terms of an equivalent circuit.

  The resonance as described above is a factor that adversely affects the frequency response of the dynamic headphone unit. When the resonance frequency in the above resonance is in a frequency band that emits sound in the dynamic headphone unit, the frequency response is deteriorated.

  In order to prevent resonance that deteriorates the frequency response in the dynamic headphone unit, it is desirable to make the air chamber as small as possible. Therefore, there is known a dynamic headphone unit having a diaphragm that flattens the shape of the diaphragm and substantially flattenes the edge portion of the diaphragm to reduce the volume of the air chamber on the back side of the voice coil (for example, Patent Documents). 1).

Japanese Patent Laying-Open No. 2015-119264

  The dynamic headphone described in Patent Document 1 includes an edge portion around a flat diaphragm. The edge portion is fixed to the unit frame so that the flat diaphragm can sufficiently vibrate back and forth. Therefore, the edge portion is softer than the planar diaphragm. Further, the edge portion plays a role of acoustically separating the front and rear of the planar diaphragm.

  The soft edge portion causes reverse resonance. This reverse resonance deteriorates the frequency response of the dynamic headphone unit. Further, the edge portion also vibrates due to the vibration of the planar diaphragm. Even if the vibration of the plane diaphragm is linear with respect to the drive current to the voice coil, the vibration of the edge portion is nonlinear with respect to the vibration of the plane diaphragm. This is because the edge portion is softer than the planar diaphragm. However, when the edge portion vibrates, the surrounding air is vibrated, so that sound is emitted by the edge portion. This sound emission adversely affects the distortion rate of the dynamic headphone unit.

  The resonance of the plane diaphragm is caused by the mass of the plane diaphragm and the stiffness of the edge portion. If the acoustic resistance is fixed to the opening of the unit frame behind the plane diaphragm, the sharpness of the resonance can be adjusted. However, it is difficult to fix the acoustic resistance after the dynamic headphone unit is incorporated in the housing. That is, it is difficult to adjust the sharpness of resonance in the dynamic headphone unit after being incorporated into the housing.

  Even after being installed in the housing, if the sharpness of resonance of the headphone unit can be adjusted arbitrarily, the sound quality can be adjusted to the listener's preference. Therefore, a headphone unit that can adjust the sharpness of resonance arbitrarily and easily even after the headphone unit is incorporated in the housing is desirable.

  An object of this invention is to provide the headphone unit which can adjust a sharpness according to a listener's favorite sound quality.

  The present invention includes a vibrator, a frame, and an edge support portion, wherein the frame includes the edge support portion, and the vibrator includes an edge portion formed on an outer edge portion of the edge support portion. The edge support portion includes a stiffness change body, a change body holding portion, and a change body characteristic variable portion, and the stiffness change body is given from the outside. It is an object whose properties reversibly change between a free fluid and a semi-solid according to the strength of energy, and the change body holding unit holds the stiffness change body so as to remain around the edge portion. The change body characteristic variable section generates the energy to be given to the stiffness change body.

  According to the present invention, the sharpness can be adjusted according to the sound quality desired by the listener.

It is a longitudinal cross-sectional view which shows the structural example of the dynamic headphone unit which concerns on this invention. It is the expanded longitudinal cross-sectional view which expanded the characteristic part of the said dynamic headphones.

  Hereinafter, as an example of a headphone unit according to the present invention, an embodiment of a dynamic headphone unit will be described with reference to the drawings. As shown in FIG. 1, the headphone unit 100 is a dynamic electroacoustic transducer having a diaphragm 10, a magnetic circuit unit 20, a unit frame 30, a protector 40, and an edge support unit 50. I have.

  The magnetic circuit unit 20 includes a yoke 21, a magnet 22, and a pole piece 23. The yoke 21 is a dish-shaped magnetic body in which the peripheral portion 21a is raised substantially at a right angle. The magnet 22 is a disk-shaped permanent magnet, and is fixed to the central portion of the bottom of the yoke 21. The pole piece 23 is a magnetic body that is stacked and fixed on the magnet 22. The magnet 22 is magnetized in the direction of its thickness. The left side of FIG. 1 is the front of the headphone unit 100, and the right side of the paper is the back. When the magnetic circuit unit 20 is viewed from the front, the outer shape of the yoke 21 and the outer shape of the pole piece 23 are both circular. The yoke 21 has a donut shape, and a pole piece 23 is disposed in a circular space inside the yoke 21.

  A gap is formed between the outer peripheral wall of the pole piece 23 and the inner periphery of the peripheral portion 21 a of the yoke 21. Since a magnetic field is generated in this gap by the magnet 22, the magnetic circuit unit 20 forms a magnetic gap between the yoke 21 and the pole piece 23.

  The unit frame 30 holds the magnetic circuit portion 20 at the center portion, and holds the edge support portion 50 at the flange portion 31 whose diameter is increased around the center portion. The detailed configuration of the edge support unit 50 will be described later. A protector 40 made of a punching metal or a metal net is attached to the peripheral portion of the flange portion 31 so as to cover the front surface of the diaphragm 10.

  The diaphragm 10 is a vibrator that vibrates ambient air by its own vibration and outputs sound waves. The diaphragm 10 can also convert sound waves into electric vibrations and output them by detecting vibrations (sound waves) of the surrounding air.

  The diaphragm 10 is a planar diaphragm formed by integrally joining a circular flat plate having a predetermined rigidity to a central portion of a base material. The material of the base material of the diaphragm 10 is a thermoplastic synthetic resin film, for example, a PET (polyethylene terephthalate) film. The material of the flat plate of the diaphragm 10 only needs to be rigid enough to be displaced as a flat plate. The material of the diaphragm 10 is, for example, a metal material, a hard synthetic resin material, a carbon material, or the like. For this flat plate, a carbon material (carbon plate) that is lightweight and does not easily deform even when a radial stress is applied to the substrate is suitable.

  An edge portion 11 having a predetermined stiffness is formed on the outer peripheral portion of the vibration plate 10, which includes a front and rear uneven pattern. The concavo-convex pattern of the edge portion 11 may be a concentric wave shape or zigzag shape, or a pattern in which these are mixed.

  The headphone unit 100 has a function of changing the stiffness of the diaphragm 10 by changing the stiffness of the edge portion 11 as described later. Therefore, the edge part 11 should just be a form which can change a stiffness in the outer peripheral part of the diaphragm 10, and is not restricted to the form shown above. For example, even if the edge portion 11 is flat rather than uneven, any shape may be used as long as the stiffness of the diaphragm 10 can be changed by the configuration described later.

  An edge portion on the outer periphery of the edge portion 11 is fixed to the diaphragm support ring 12. The diaphragm support ring 12 is supported by the flange portion 31 of the unit frame 30 via an edge support portion 50 described later. A predetermined tension is applied to the edge portion 11 between the diaphragm support ring 12 and the diaphragm 10, one end of the edge portion 11 is fixed to the diaphragm 10, and the other end is the diaphragm support ring 12. It is fixed to. When the edge portion 11 is fixed as described above in a state where a predetermined tension is applied, the diaphragm 10 is also held by the unit frame 30 in a state where the predetermined tension is applied.

  A voice coil 13 disposed in the magnetic gap is fixed to the rear side (back side) of the diaphragm 10. Therefore, the diaphragm 10 has a larger diameter than the outer diameter of the voice coil 13. The size of the diaphragm 10 is preferably a larger diameter, but must be a size that can be accommodated inside the unit frame 30. Even if the size of the diaphragm 10 becomes larger, the region of the edge portion 11 must be secured to some extent so that the vibration when the diaphragm 10 outputs sound waves can be allowed. Therefore, the size of the diaphragm 10 is limited by the size of the unit frame 30 and the size of the region of the edge portion 11 necessary for vibration.

  The gap between the pole piece 23 and the diaphragm 10 on the back side of the diaphragm 10 and the dimensions of the unit frame 30 and the diaphragm 10 and the gap need only to be larger than the maximum value at which the diaphragm 10 is displaced. Thereby, the volume of the air chamber on the back side of the diaphragm 10 can be reduced as much as possible. Further, the gap can be set almost uniformly with respect to the entire diaphragm 10.

  Next, the edge support part 50 is demonstrated using FIG. The edge support part 50 acoustically separates the space before and after the diaphragm 10 together with the diaphragm 10 and the edge part 11. The edge support portion 50 is fixed to the inside of the enlarged diameter portion of the unit frame 30. The edge support portion 50 includes a stiffness change body 51, a change body holding portion including a ring magnet 52, a front yoke 54, and a rear yoke 55, and a coil 53. The edge support part 50 can change the stiffness of the edge part 11. In other words, the edge support part 50 can adjust the stiffness of the edge part 11. By adjusting the stiffness of the edge portion 11 to a predetermined value, the stiffness of the diaphragm 10 becomes variable. According to such an embodiment, the stiffness of the diaphragm 10 can be adjusted.

  The stiffness changing body 51 is a material whose rigidity and viscosity change according to energy applied from the outside. The stiffness changing body 51 is, for example, a magnetorheological fluid known as a functional fluid (Magneto Rheological Fluid fluid: MR fluid). MR fluid changes its hardness between free fluid and semi-solid depending on the strength of the applied magnetic field. That is, when MR fluid is used as the stiffness changing body 51, the energy applied from the outside is magnetism.

  The ring magnet 52 constituting the change body holding part is a ring-shaped permanent magnet arranged along the inner peripheral surface of the flange part 31. Further, the front yoke 54 and the rear yoke 55 constituting the change body holding part form a magnetic circuit together with the ring magnet 52. This magnetic circuit generates a magnetic field having a certain strength in a space corresponding to the thickness of the ring magnet 52 formed between the surfaces of the front yoke 54 and the rear yoke 55 facing each other.

  The stiffness changing body 51 remains between the front yoke 54 and the rear yoke 55 due to the influence of the magnetic field. Although the space between the front yoke 54 and the rear yoke 55 is opened on the diaphragm 10 side, the outflow from the opening of the stiffness changing body 51 does not occur due to the action of the magnetic field generated by the ring magnet 52.

  The coil 53 is a variable body characteristic variable unit and is disposed on the inner peripheral side of the ring magnet 52. The diaphragm support ring 12 is fixed to the inner peripheral wall of the coil 53.

  When a power source is connected to the end of the conducting wire forming the coil 53 and an exciting current flows, the coil 53 generates a magnetic field having a strength corresponding to the magnitude of the exciting current. This magnetic field is applied to the stiffness changing body 51.

  Next, the operation of the edge support unit 50 in the headphone unit 100 will be described. Since the stiffness changing body 51 is an MR fluid, when a magnetic field is applied, the viscosity changes according to the strength of the magnetic field. The viscosity of the stiffness changing body 51 reversibly changes with the strength of the magnetic field. In a strong magnetic field, the stiffness changing body 51 has a high viscosity, and in a weak magnetic field, the stiffness changing body 51 has a low viscosity.

  When the value of the excitation current to the coil 53 increases, the magnetic field applied from the coil 53 to the stiffness changing body 51 increases, and when the value of the excitation current decreases, the magnetic field decreases. Accordingly, the stiffness of the stiffness changing body 51 becomes stronger and harder as the value of the excitation current increases, and the viscosity of the stiffness changing body 51 becomes weaker and softer as the value of the excitation current decreases.

  As shown in FIG. 2, the stiffness changing body 51 surrounds the periphery of the edge portion 11. As described above, when the viscosity of the stiffness changing body 51 is increased, the edge portion 11 is less likely to vibrate. In other words, the stiffness changing body 51 prevents unnecessary sound emission by fixing the edge portion 11. The stiffness changing body 51 prevents reverse resonance in the edge portion 11. As a result, it is possible to prevent a decrease in frequency response performance in the headphone unit 100.

  Further, if the viscosity of the stiffness changing body 51 is adjusted by adjusting the value of the excitation current to the coil 53, the stiffness of the edge portion 11 can be adjusted. The resonance frequency of the diaphragm 10 is variable by adjusting the stiffness of the edge portion 11. Further, the sharpness (Q value) at the time of resonance can be adjusted.

  The headphone unit 100 described above does not adjust the frequency response or the resonance frequency by setting the acoustic characteristics using acoustic resistance or the like, but enables the same electrical adjustment.

  For example, according to a headphone in which a switch (for example, a volume switch) that changes the magnitude of the excitation current to the coil 53 is provided in the housing of the headphone unit 100, the user can arbitrarily set the stiffness of the edge portion 11 during use. Can be adjusted to the sound quality desired by the user.

DESCRIPTION OF SYMBOLS 10 Diaphragm 11 Edge part 12 Diaphragm support ring 13 Voice coil 20 Magnetic circuit part 21 Yoke 22 Magnet 23 Pole piece 30 Unit frame 31 Flange part 50 Edge support part 51 Stiffness variable part 52 Ring magnet 53 Coil 54 Front yoke 55 Rear yoke 100 Headphone unit

Claims (5)

Having a vibrator, a frame, and an edge support,
The frame includes the edge support;
The vibrator has an edge portion formed at an outer edge portion supported by the frame via the edge support portion,
The edge support portion includes a stiffness change body, a change body holding portion, and a change body characteristic variable portion,
The stiffness changing body is an object whose properties change reversibly between a free fluid and a semi-solid according to the strength of energy given from the outside,
The change body holding portion holds the stiffness change body so as to remain around the edge portion,
The variable body characteristic variable unit generates the energy to be given to the stiffness change body.
A headphone unit characterized by this. The stiffness changing body is an MR fluid,
The variable body characteristic variable unit is a coil that applies a magnetic field according to the magnitude of an excitation current to the MR fluid.
The headphone unit according to claim 1. The vibrator is a flat diaphragm obtained by integrally bonding a base material and a circular flat body.
The headphone unit according to claim 1 or 2. The edge portion has front and rear uneven patterns in the vibrator,
The headphone unit according to claim 1. Having a magnetic circuit with a magnetic gap;
The frame has the magnetic circuit fixed at the center and the edge portion fixed at the periphery,
The vibrator is a diaphragm in which the edge portion is formed on a base material and an outer peripheral portion of the base material,
The diaphragm is supported by the frame via the edge portion and the edge support portion so that a voice coil is fixed to one surface of the base material and the voice coil is disposed in the magnetic gap. The
The headphone unit according to claim 1.

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