Driver unit and headphones

Abstract

The present disclosure relates to a driver unit and headphones that allow for better sound quality. The driver unit comprises: a magnetic circuit formed from a magnetic material; a voice coil which is formed by winding a coil around a bobbin and which is disposed in a magnetic gap of the magnetic circuit; a diaphragm to which the voice coil is joined; and a frame for supporting an outer edge portion of the diaphragm. The bobbin has a plurality of air holes along the cylindrical surface thereof. The present disclosure can be applied to driver units provided inside the housings of headphones.

Description

Driver units and headphones

[0001] The present disclosure relates to a driver unit and headphones, and more particularly to a driver unit and headphones that further improve sound quality.

[0002] Patent document 1 discloses a speaker device in which a damping member having an air vent is placed between a dome-shaped diaphragm and a pole in a dome-shaped speaker, thereby reducing resonance between the dome-shaped diaphragm and the pole.

[0003] JP 2010-34988 A

[0004] In headphones, it can be difficult to stably adjust the frequency characteristics due to their structure.

[0005] The present disclosure has been made in view of such circumstances, and aims to further improve sound quality.

[0006] The driver unit of the present disclosure comprises a magnetic circuit formed from a magnetic material, a voice coil formed by winding a coil around a bobbin and disposed in a magnetic gap of the magnetic circuit, a diaphragm to which the voice coil is joined, and a frame supporting the outer edge of the diaphragm, the bobbin having a plurality of air holes along the cylindrical surface of the bobbin.

[0007] The headphones disclosed herein are headphones comprising a magnetic circuit formed from a magnetic material, a voice coil formed by winding a coil around a bobbin and disposed in a magnetic gap of the magnetic circuit, a diaphragm to which the voice coil is joined, and a frame supporting the outer edge of the diaphragm, the bobbin including a driver unit having a plurality of air holes along the cylindrical surface of the bobbin.

[0008] In the present disclosure, in a driver unit comprising a magnetic circuit formed from a magnetic material, a voice coil formed by winding a coil around a bobbin and disposed in a magnetic gap of the magnetic circuit, a diaphragm to which the voice coil is joined, and a frame supporting the outer edge of the diaphragm, the bobbin is provided with a plurality of air holes along the cylindrical surface of the bobbin.

[0009] FIG. 1 is a diagram illustrating an example of the external configuration of headphones according to an embodiment of the present disclosure; FIG. 2 is a cross-sectional view illustrating an example of the configuration of a driver unit; FIG. 3 is a side view illustrating an example of the configuration of a voice coil; FIG. 4 is a diagram illustrating an air flow path in a conventional driver unit; FIG. 5 is a diagram illustrating an air flow path in a driver unit of the present disclosure; FIG. 6 is a diagram comparing measurement results of frequency characteristics of driver units; FIG. 7 is a diagram illustrating an example of an acoustic resistor in a conventional driver unit; and FIG. 8 is a diagram illustrating an example of an acoustic resistor in a driver unit of the present disclosure.

[0010] Modes for carrying out the present disclosure (hereinafter referred to as embodiments) will be described below in the following order.

[0011] 1. Prior art and its problems 2. Headphone configuration 3. Air flow path in the driver unit 4. Acoustic resistor

[0012] <1. Prior Art and Its Problems> A known method for adjusting the frequency characteristics of a driver unit installed inside a headphone housing is to create an air vent in the center of the magnetic circuit and attach an air register to the air vent to adjust the compliance of the air inside the voice coil. However, in a mechanism in which components that make up the housing are located on the back side (air register side) of the magnetic circuit in the driver unit, the flow of air in and out of the voice coil is obstructed. In this case, it becomes difficult to stably adjust the frequency characteristics.

[0013] Some speaker voice coils have holes in the bobbin that makes up the voice coil for the purpose of heat dissipation. However, most of these bobbins are made of metal or film, and there were no bobbins that were lightweight, rigid, and had the appropriate internal loss required for driver units in headphones.

[0014] In contrast, in the technology disclosed herein, holes are provided in the bobbin that constitutes the voice coil so that air inside the voice coil can flow in and out from the frame side that supports the outer edge of the diaphragm, rather than through the vent hole in the center of the magnetic circuit, thereby improving the compliance of the air inside the voice coil.

[0015] 2. Headphone Configuration> (External Configuration Example of Headphones) FIG. 1 is a diagram showing an external configuration example of headphones according to an embodiment of the present disclosure.

[0016] 1 is composed of a pair of headphone bodies 11 and a headband 12. Each headphone body 11 is composed of a housing 21 and flexible ear pads 22 attached to the housing 21.

[0017] When the headband 12 is attached to the user's head and the ear pads 22 are placed against the user's temples and ears, the user can perceive sound converted from an electrical signal by a driver unit (not shown) provided inside the housing 21.

[0018] (Configuration Example of Driver Unit) FIG. 2 is a cross-sectional view showing a configuration example of a driver unit provided inside the housing 21. As shown in FIG.

[0019] A typical driver unit including driver unit 100 shown in Fig. 2 has a shape that is rotationally symmetrical about a central axis that is parallel to the direction toward the user's ear. In the following description, the side of driver unit 100 that faces the user's ear is referred to as the front side, and the opposite side as the back side. In Fig. 2, the upper side is the front side of driver unit 100.

[0020] As shown in FIG. 2, the driver unit 100 is configured to include a magnetic circuit 110 , an acoustic resistor 120 , a voice coil 130 , a diaphragm 140 , a frame 150 , and an acoustic resistor 160 .

[0021] The magnetic circuit 110 is made of a magnetic material and includes a yoke 111, a magnet 112, and a pole piece 113.

[0022] The yoke 111 is a generally cylindrical component having a bottom surface and a side surface erected on the bottom surface, and is made of a magnetic material such as iron. A known magnet 112, such as a magnet containing rare earth particles such as neodymium, a ferrite magnet, or a cobalt magnet, is provided on the bottom surface of the yoke 111. A pole piece 113, made of a magnetic material such as iron, is provided on the top surface of the magnet 112.

[0023] The magnetic circuit 110 has a vent hole 110v at its center, which is formed so as to penetrate the yoke 111, the magnet 112, and the pole piece 113. An acoustic resistor 120, which is formed of, for example, a nonwoven fabric sheet, is provided at the opening of the vent hole 110v on the back side of the yoke 111 to control the amount of airflow (airflow resistance) through the vent hole 110v. Note that the vent hole 110v does not necessarily have to be formed at the center of the magnetic circuit 110, and may be formed at a position offset from the center of the magnetic circuit 110 in a plan view.

[0024] A voice coil 130 is disposed in the magnetic gap formed between the side surface of the yoke 111 and the magnet 112 and pole piece 113. An acoustic signal (acoustic current) is input to the voice coil 130, and a Lorentz force corresponding to the magnitude of the input acoustic current is generated by the magnetic field created by the magnet 112. The voice coil 130 vibrates due to the generated Lorentz force.

[0025] A diaphragm 140, which is circular in plan view from the front surface side, is joined to the voice coil 130. The diaphragm 140 vibrates when vibrations from the voice coil 130 are transmitted to the diaphragm 140. This converts the acoustic current into sound.

[0026] The frame 150 is formed in a circular ring shape. The yoke 111 of the magnetic circuit 110 is fitted and locked inside the circular frame 150, and the outer edge of the diaphragm 140 is supported by the frame 150.

[0027] Frame 150 has communication port 150c that exhausts air on the back side of diaphragm 140 to the outside. An acoustic register 160 that controls the amount of airflow (airflow resistance) through communication port 150c is provided at the opening of communication port 150c on the back side of frame 150. Acoustic register 160 is made of, for example, mesh-like fibers (including synthetic fibers) and is formed so that the amount of airflow through communication port 150c is approximately uniform.

[0028] (Configuration Example of Voice Coil) FIG. 3 is a side view showing a configuration example of the voice coil 130. As shown in FIG.

[0029] 3, the voice coil 130 is formed by winding a coil 220 around a cylindrical bobbin 210. The voice coil 130 vibrates when the acoustic current described above is input to the coil 220. Although not shown, a diaphragm 140 is joined to the upper side of the voice coil 130 in the drawing.

[0030] The bobbin 210 is formed from multiple layers of kraft material, for example, two layers. The bobbin 210 may also be formed from a single layer of highly rigid kraft material. The bobbin 210 is also formed by spiral winding. This allows the bobbin 210 to be lightweight, rigid, and have appropriate internal loss. Note that the bobbin 210 is not limited to kraft material, and may be formed from a metal such as aluminum or a resin film such as polyimide, as long as it is lightweight, rigid, and has appropriate internal loss.

[0031] Furthermore, bobbin 210 has a plurality of air holes 230 along its cylindrical surface (the portion where coil 220 is not wound). The diameter, number, spacing, and shape of the plurality of air holes 230 formed on the cylindrical surface of bobbin 210 may be designed as appropriate. As will be described later, the plurality of air holes 230 can form an air flow path between the inside of voice coil 130 and communication port 150c provided in frame 150.

[0032] 3. Air flow path in driver unit> Here, the air flow path in a conventional driver unit and the air flow path in the driver unit of the present disclosure will be compared with each other with reference to Fig. 4 and Fig. 5. Fig. 4 is a diagram illustrating the air flow path in the conventional driver unit. Fig. 5 is a diagram illustrating the air flow path in the driver unit of the present disclosure.

[0033] 4, in conventional driver unit 100A, air flows in and out between the inside of voice coil 310 and the back side of acoustic register 120, with vent hole 110v serving as air flow path FP1, in response to vibration of diaphragm 140. Also, in conventional driver unit 100A, air flows in and out between the back side of diaphragm 140 (the inside of frame 150) and the back side of acoustic register 160, with communication hole 150c serving as air flow path FP2, in response to vibration of diaphragm 140.

[0034] However, if components constituting housing 21 are arranged on the back side of magnetic circuit 110 in conventional driver unit 100A, the flow of air inside voice coil 130 is obstructed, making it difficult to stably adjust the frequency characteristics.

[0035] On the other hand, in the driver unit 100 of the present disclosure shown in Figure 5, in addition to the air flow paths FP1 and FP2 similar to those of the driver unit 100A of Figure 4, a plurality of air holes 230 form an air flow path FP3 between the inside of the voice coil 130 and the communication port 150c.

[0036] That is, in the driver unit 100 of the present disclosure, the multiple air holes 230 allow air inside the voice coil 130 to flow in and out from the frame 150 side that supports the outer edge of the diaphragm 140, rather than through the central air vent 110v of the magnetic circuit 110. This makes it possible to improve the compliance of the air inside the voice coil 130, even in a mechanism in which components that make up the housing 21 are arranged on the back side of the magnetic circuit 110. Note that, although the magnetic circuit 110 has the air vent 110v in the driver unit 100 of the present disclosure, the magnetic circuit 110 does not necessarily have to have the air vent 110v. Even if the magnetic circuit 110 does not have the air vent 110v, the multiple air holes 230 in the driver unit 100 allow air inside the voice coil 130 to flow in and out from the frame 150 side that supports the outer edge of the diaphragm 140, thereby achieving the above-mentioned advantageous effects.

[0037] FIG. 6 is a diagram comparing the measurement results of the frequency characteristics of a conventional driver unit 100A and a driver unit 100 of the present disclosure.

[0038] Figure 6 shows the frequency characteristics (dashed line) of headphones equipped with a conventional driver unit 100A measured using a coupler (artificial ear) compliant with IEC 60318-1, and the frequency characteristics (solid line) of headphones equipped with the driver unit 100 of the present disclosure.

[0039] 6, the frequency characteristics of headphones equipped with conventional driver unit 100A have dips and peaks in the frequency band fc of 2 kHz (2000 Hz) to 4 kHz (4000 Hz). On the other hand, headphones equipped with driver unit 100 of the present disclosure have smoothed frequency characteristics in the frequency band fc (2 kHz to 4 kHz).

[0040] In this way, with a voice coil 130 having multiple air holes 230 along the cylindrical surface of the bobbin 210, it is possible to smooth the frequency characteristics from 2 kHz to 4 kHz by improving the compliance of the air inside the voice coil 130. This in turn makes it easier to achieve a noise canceling effect, and further improves sound quality.

[0041] 4. Acoustic Resistor Here, the acoustic resistor in a conventional driver unit and the acoustic resistor in the driver unit of the present disclosure will be compared with each other with reference to Fig. 7 and Fig. 8. Fig. 7 is a diagram showing an example of the acoustic resistor in a conventional driver unit. Fig. 8 is a diagram showing an example of the acoustic resistor in the driver unit of the present disclosure.

[0042] In the conventional driver unit 100B shown in Fig. 7, an acoustic register 320 that controls the amount of airflow through a communication port 150c (not shown) is provided on the back side of a ring-shaped frame 150. Like the acoustic register 120, the acoustic register 320 is formed, for example, from a nonwoven fabric sheet. Furthermore, the acoustic register 320 is provided with a plurality of holes 320h for increasing the amount of airflow through the communication port 150c. In this case, a difference in airflow between the holes 320h of the acoustic register 320 and other locations may occur, potentially causing sound distortion.

[0043] On the other hand, in the driver unit 100 of the present disclosure shown in Fig. 8, an acoustic register 160 that controls the amount of airflow through a communication port 150c (not shown) is provided on the back side of the annular frame 150. As described above, the acoustic register 160 is formed so that the amount of airflow through the communication port 150c is approximately uniform. This prevents differences in the amount of airflow across the entire acoustic register 160, suppressing sound distortion and further improving sound quality.

[0044] It should be noted that the embodiments of the technology according to the present disclosure are not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the technology according to the present disclosure.

[0045] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0046] The technology disclosed herein may also be configured as follows: (1) A driver unit including: a magnetic circuit made of a magnetic material; a voice coil formed by winding a coil around a bobbin and disposed in a magnetic gap of the magnetic circuit; a diaphragm to which the voice coil is joined; and a frame supporting the outer edge of the diaphragm, the bobbin having a plurality of air holes along the cylindrical surface of the bobbin. (2) The driver unit described in (1), in which the frame has a communication port for exhausting air on the back side of the diaphragm to the outside, the plurality of air holes forming an air flow path between the inside of the voice coil and the communication port. (3) The driver unit described in (2), further including an acoustic resistor with a substantially uniform airflow rate provided at the opening of the communication port. (4) The driver unit described in any of (1) to (3), in which the bobbin is formed of a single-layer or multiple-layer kraft material. (5) The driver unit described in (4), in which the bobbin is formed by spiral winding. (6) The driver unit according to any one of (1) to (5), wherein the magnetic circuit has an air vent formed so as to penetrate the magnetic circuit. (7) The driver unit according to (6), wherein the air vent is formed in the center of the magnetic circuit. (8) Headphones including a driver unit comprising: a magnetic circuit formed of a magnetic material, a voice coil formed by winding a coil around a bobbin and disposed in a magnetic gap of the magnetic circuit, a diaphragm to which the voice coil is joined, and a frame supporting an outer edge of the diaphragm, wherein the bobbin has a plurality of air holes along a cylindrical surface of the bobbin.

[0047] 1 Headphones, 11 Headphone body, 12 Headband, 21 Housing, 22 Ear pads, 100 Driver unit, 110 Magnetic circuit, 110v Ventilation port, 111 Yoke, 112 Magnet, 113 Pole piece, 120 Acoustic resistor, 130 Voice coil, 140 Diaphragm, 150 Frame, 150c Communication port, 160 Acoustic resistor, 210 Bobbin, 220 Coil, 230 Air hole

Claims

1. A driver unit comprising: a magnetic circuit formed from a magnetic material; a voice coil formed by winding a coil around a bobbin and disposed in a magnetic gap of the magnetic circuit; a diaphragm to which the voice coil is joined; and a frame supporting the outer edge of the diaphragm, wherein the bobbin has a plurality of air holes along its cylindrical surface.

2. The driver unit according to claim 1, wherein the frame has a communication port for discharging air on the back side of the diaphragm to the outside, and the plurality of air holes form an air flow path between the inside of the voice coil and the communication port.

3. The driver unit according to claim 2, further comprising an acoustic resistor provided at the opening of the communication port and having a substantially uniform airflow rate.

4. The driver unit according to claim 1, wherein the bobbin is made of a single layer or multiple layers of craft material.

5. The driver unit according to claim 4, wherein the bobbin is formed by spiral winding.

6. The driver unit according to claim 1, wherein the magnetic circuit has a vent hole formed so as to penetrate the magnetic circuit.

7. The driver unit according to claim 6, wherein the vent is formed in the center of the magnetic circuit.

8. Headphones including a driver unit comprising: a magnetic circuit formed from a magnetic material; a voice coil formed by winding a coil around a bobbin and disposed in a magnetic gap of the magnetic circuit; a diaphragm to which the voice coil is joined; and a frame supporting the outer edge of the diaphragm, wherein the bobbin has a plurality of air holes along the cylindrical surface of the bobbin.

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