JP2010011328A - Headphone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a headphone that maintains acoustic characteristics necessary for the headphone by using configurations specific to the headphone in order to prevent noise which is caused by an external electromagnetic wave from being generated. <P>SOLUTION: The headphone includes a headphone unit 1 having a diaphragm 6 which is driven with an audio signal to generate a sound wave, a circuit board 12 disposed behind the headphone unit 1 and having a hole 121 communicating with a sound hole 22 of the headphone unit 1, and a shield and acoustic resistance material 16 disposed covering the back of the headphone unit 1 together with the circuit board 12. The shield and acoustic resistance material 16 is made of conductive fabric. The headphone has a resin-made baffle plate 10 to which the headphone unit 1 and circuit board 12 are fixed, and a conductive layer is formed on a surface of the baffle plate 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to headphones, and in particular, has a feature in the structure of a shield structure for preventing the generation of noise due to electromagnetic waves and the structure of an acoustic resistance material for improving frequency response.

  A general headphone includes a headphone unit having a structure similar to that of a dynamic speaker as a main component. In the case of ear-cover type headphones, the headphone unit is generally attached to the baffle plate, an ear pad is attached to the front side of the baffle plate, and a housing that covers the headphone unit is attached to the back side of the baffle plate .

  FIG. 2 shows an example of a conventional ear covering type headphone. In FIG. 2, reference numeral 1 denotes a headphone unit. The headphone unit 1 has a unit frame 2 as a base, and includes a magnetic circuit component member, a diaphragm 6 and a voice coil 7 as main components. The magnetic circuit component includes a dish-shaped yoke 3, a magnet 4 fixed to the inner bottom surface of the yoke 3, and a pole piece 5 fixed to the front end surface of the magnet 4. A cylindrical gap is formed over the entire circumference between the inner peripheral surface of the front end portion of the yoke 3 and the outer peripheral surface of the pole piece 5. There is a gap.

  The outer periphery of the yoke 3 is fitted into a cylindrical portion 21 formed at the center of the unit frame 2, and is integrated with the unit frame 2. The diaphragm 6 includes a main dome at the center and a sub dome surrounding the main dome. The outer peripheral edge of the sub dome is fixed to the front outer peripheral edge of the unit frame 2. The diaphragm 6 is a thin plate-like component made of, for example, resin, and can vibrate in the front-rear direction with the outer peripheral edge fixed to the unit frame 2 as a fulcrum. The front end of the voice coil 7 is fixed to the rear side of the diaphragm 6 along the boundary between the main dome and the sub dome. The voice coil 7 is a part formed by winding a thin conducting wire in a cylindrical shape, and is disposed in the magnetic gap, and can move in the front-rear direction without touching the yoke 3 and the pole piece 5 together with the diaphragm 6. ing.

  As apparent from the configuration described above, since the voice coil 7 is disposed in the magnetic gap, when an audio signal is input to the voice coil 7, the current according to the audio signal and the magnetic flux in the magnetic gap are reduced. Due to the electromagnetic force, the voice coil 7 moves in the front-rear direction. Since the diaphragm 6 vibrates back and forth together with the voice coil 7, sound waves according to the audio signal are emitted from the diaphragm 6.

  The headphone unit 1 has its unit frame 2 fitted and fixed in a hole provided in the center of the baffle plate 10. An ear pad 13 is fixed to the front peripheral edge of the baffle plate 10, and a bowl-shaped housing 14 is fixed to the back side of the baffle plate 10. If a space is formed between the diaphragm 6 and the magnetic circuit component, and this space is a sealed space, the air in this space acts as a spring and the diaphragm 6 serves as an audio signal. It becomes impossible to vibrate faithfully. Therefore, an appropriate number of acoustic holes 22 are formed in the unit frame 2 so that the internal space of the headphone unit 1 communicates with the space behind the headphone unit 1. Further, in order to improve the frequency response by giving an appropriate damping characteristic to the diaphragm 6, an acoustic resistance material 25 is attached to the unit frame 2 to cover the acoustic hole 22. As the acoustic resistance material 25, a material that has an appropriate resistance to air circulation, such as open-cell sponge, glass wool, and nonwoven fabric, is selected.

  A jetty 11 is formed on the back side of the baffle plate 10 so as to surround the attachment portion of the headphone unit 1 on the outer peripheral side of the attachment portion of the headphone unit 1. The circuit board 12 is overlapped and fixed to the tip (right end in FIG. 2) of the jetty 11. A hole is formed at the center of the circuit board 12, and this hole communicates with the acoustic hole 22 of the unit frame 2. An acoustic resistance material 20 is stacked and fixed on the circuit board 12, and the hole in the center portion of the circuit board 12 is covered with the acoustic resistance material 20. In order to improve the frequency response of the headphone unit 1, the acoustic resistance value of the acoustic resistance material 20 is set to an appropriate value.

A protector 8 is disposed in front of the diaphragm 6 so that the diaphragm 6 cannot be touched from the outside. The protector 8 has substantially the same shape as the diaphragm 6, and the outer peripheral edge is fixed to the front surface of the baffle plate 10 with a certain distance from the front surface of the diaphragm 6. The protector 8 is formed with an appropriate number of holes for passing the sound wave from the diaphragm 6.
The headphones configured as described above are usually paired with a pair of headbands to form stereo headphones.

  The headphone described above is used by a user wearing it on the head, so that it is desired to be as light as possible. Therefore, plastic parts are more often used as component parts than metal parts. For example, in the conventional example shown in FIG. 2, the baffle plate 10, the unit frame 2, the protector 8, and the like are often made of plastic. Therefore, the structure is such that electromagnetic waves from the outside easily penetrate through the plastic parts.

  In general headphones, problems due to the invasion of electromagnetic waves are not so noticeable, but noise canceling headphones are equipped with an electronic circuit for noise cancellation, so the invading electromagnetic waves are detected by electronic circuit components, Generate noise. In particular, in recent years, mobile phones are often used near headphones due to the widespread use of mobile phones, and when electromagnetic waves radiated from nearby mobile phones enter the headphones, the level of noise generated by detection by electronic circuits is reduced. Get higher. In the case of headphones, noise caused by electromagnetic waves, that is, high-frequency currents, enters the ear directly as sound waves, so there is a concern that the user may feel uncomfortable when the noise level is high.

  Therefore, the present invention has been devised so that the headphone can effectively block electromagnetic waves entering from the outside in order to prevent the generation of noise caused by the electromagnetic waves. However, in various electronic devices, in order to shield the electromagnetic waves, as described below, a device specific to each electronic device is made.

  In Patent Document 1, in an electronic device such as a portable computer, a recess for accommodating a hard disk drive device (hereinafter referred to as “HDD”) or the like is provided, and a shield layer is formed on the inner surface of the recess. There is described a shield structure for an HDD in which a conductive member that conducts current is provided, and the recess is covered with an HDD cover having a shield layer on the inner surface.

  Patent Document 2 includes an electronic device such as a mobile phone that includes a substrate on which an electronic component is mounted and a shield case that shields the electronic component. The shield case covers the electronic component and is attached to the mounting surface. The shield base includes a shield base having a first opening that exposes an electronic component on an opposing surface, and a shield cover attached to the shield base so as to cover the first opening. The shield cover is inserted into the first opening. A shield structure in which a pressing portion that presses an electronic component toward the substrate is provided is described.

  Both the invention described in Patent Document 1 and the invention described in Patent Document 2 shield the electronic parts unique to each electronic device with a unique shield structure based on the configuration unique to the configuration of each electronic device.

JP 2007-328531 A JP 2007-299814 A

  An object of the present invention is to provide a headphone capable of maintaining the acoustic characteristics required of a headphone by utilizing a configuration unique to the headphone in preventing the occurrence of noise caused by an external electromagnetic wave. To do.

  A headphone according to the present invention includes a headphone unit that includes a diaphragm that is driven by an audio signal and emits a sound wave, a circuit board that is disposed behind the headphone unit and communicates with an acoustic hole of the headphone unit, and the circuit board. In addition, the main feature is that it includes a shield / acoustic resistance material arranged to cover the back of the headphone unit.

  According to the headphones of the present invention, since the shield / acoustic resistance material is disposed so as to cover the circuit board together with the headphone unit, electromagnetic waves from the outside are prevented from entering the circuit board. A problem that noise is generated by detecting electromagnetic waves can be prevented. Since the shield / acoustic resistance material also functions as acoustic resistance, it is possible to adjust the acoustic characteristics of the headphones, and it is possible to obtain a great effect as headphones even though the configuration is relatively simple. .

The shield / acoustic resistance material may be composed of a conductive cloth.
The shield effect can be further enhanced by providing a resin-made baffle plate to which the headphone unit and the circuit board are fixed, and forming a conductive layer on the surface of the baffle plate.
If the shield and acoustic resistance material is electrically connected to the conductive layer on the surface of the baffle plate, the shielding effect can be further enhanced.

Hereinafter, embodiments of the headphones according to the present invention will be described with reference to FIG. The same components as those of the conventional example shown in FIG.
In FIG. 1, reference numeral 1 denotes a headphone unit. The headphone unit 1 has a unit frame 2 as a base, and includes a magnetic circuit component member, a diaphragm 6 and a voice coil 7 as main components. The magnetic circuit component includes a dish-shaped yoke 3, a disk-shaped magnet 4 fixed to the inner bottom surface of the yoke 3, and a disk-shaped pole piece fixed to the front end surface of the magnet 4. 5 is provided. A cylindrical gap is formed over the entire circumference between the inner peripheral surface of the front end (left end in FIG. 1) of the yoke 3 and the outer peripheral surface of the pole piece 5. This gap is a magnetic flux generated from the magnet 4. As a result, a magnetic gap is formed. The material of the unit frame 2 may be a metal, or a resin may be used to reduce the weight.

  The yoke 3 is integrated with the unit frame 2 by fitting the outer periphery of the yoke 3 into a cylindrical portion 21 formed at the center of the unit frame 2. The diaphragm 6 includes a main dome at the center and a sub dome surrounding the main dome. The outer peripheral edge of the sub dome is fixed to the front outer peripheral edge of the unit frame 2. The diaphragm 6 is a thin plate-like component made of, for example, resin, and can vibrate in the front-rear direction with the outer peripheral edge fixed to the unit frame 2 as a fulcrum. The front end of the voice coil 7 is fixed to the rear side of the diaphragm 6 along the boundary between the main dome and the sub dome. The voice coil 7 is a part formed by winding a thin conducting wire in a cylindrical shape, and is disposed in the magnetic gap, and can move in the front-rear direction without touching the yoke 3 and the pole piece 5 together with the diaphragm 6. ing.

  The headphone unit 1 has its unit frame 2 fitted and fixed in a hole provided in the center of the baffle plate 10. An ear pad 13 is fixed to the front peripheral edge of the baffle plate 10, and a bowl-shaped housing 14 is fixed to the back side of the baffle plate 10. An internal space is formed between the diaphragm 6 and the magnetic circuit constituent member. An appropriate number of acoustic holes 22 are formed in the unit frame 2, and the internal space of the headphone unit 1 communicates with the space behind the headphone unit 1 through the acoustic holes 22. Further, in order to improve the frequency response by giving an appropriate damping characteristic to the diaphragm 6, an acoustic resistance material 25 is attached to the unit frame 2 to cover the acoustic hole 22. As the acoustic resistance material 25, a material that has an appropriate resistance to air circulation, such as open-cell sponge, glass wool, and nonwoven fabric, is selected.

  A jetty 11 is formed on the back side of the baffle plate 10 so as to surround the attachment portion of the headphone unit 1 on the outer peripheral side of the attachment portion of the headphone unit 1. A circuit board 12 is overlapped and fixed to the tip (right end in FIG. 1) of the jetty 11. A hole 121 is formed at the center of the circuit board 12, and the hole 121 communicates with the acoustic hole 22 of the unit frame 2.

  Since the voice coil 7 is disposed in the magnetic gap, when a voice signal is input to the voice coil 7, the voice coil 7 is moved in the front-rear direction by the electromagnetic force between the current according to the voice signal and the magnetic flux in the magnetic gap. Move to. Since the diaphragm 6 vibrates back and forth with the voice coil 7, sound waves according to the audio signal are emitted from the diaphragm 6.

In the conventional example shown in FIG. 2 described above, the acoustic resistance material 20 is overlapped and fixed to the circuit board 12, the hole 121 in the central portion of the circuit board 12 is covered with the acoustic resistance material 20, and the frequency response of the headphone unit 1. In order to improve this, the acoustic resistance value of the acoustic resistance material 20 was set to an appropriate value.
In the embodiment of the present invention shown in FIG. 1, a shield / acoustic resistance material 16 is arranged instead of the acoustic resistance material 20, and the shield / acoustic resistance material 16 covers the back of the headphone unit 1 together with the circuit board 12. . As the shield / acoustic resistance material 16, a material having a shielding effect that blocks electromagnetic waves and an acoustic resistance effect that provides an appropriate resistance to transmission of sound waves is selected. As a material suitable as the shield and acoustic resistance material 16, there is a conductive cloth. In the embodiment shown in FIG. 1, a conductive cloth "Sui-78-5050T" manufactured by Seiren Co., Ltd. was used.

  In order to reduce the weight of the headphones, the baffle plate 10 is made of resin, and electromagnetic waves can pass through the baffle plate 10. Therefore, a conductive layer is formed on the surface of the baffle plate 10 by a technique such as plating. The shield / acoustic resistance material 16 has a sufficiently larger area than the circuit board 12, is bent toward the circuit board 12 along the outer peripheral edge of the circuit board 12, and is held by the inner peripheral surface of the housing 14. The outer peripheral edge portion of the shield / acoustic resistance material 16 is in contact with the conductive layer on the surface of the baffle plate 10 and passes therethrough. The conductive layer of the baffle plate 10 is grounded by being connected to a ground electrode.

  As described above, since the back side of the headphone unit 1 is covered with the shield / acoustic resistance material 16 together with the circuit board 12, the electromagnetic wave that is about to enter from the back side of the headphones is blocked by the shield / acoustic resistance material 16. . This shielding effect is particularly effective in active noise cancellation headphones. The active noise canceling headphone includes a microphone for detecting environmental noise and a cancel signal generating circuit for canceling the environmental noise detected by the microphone, and circuit elements constituting the cancel signal generating circuit are mounted on the circuit board 12. The When electromagnetic waves enter this circuit element, it is detected and generates noise. However, according to the embodiment shown in FIG. 1, the generation of noise can be prevented by blocking the penetration of electromagnetic waves into the circuit board 12 by the shield / acoustic resistance material 16. Since the shield / acoustic resistance material 16 passes through the conductive layer on the surface of the baffle plate 10, the shielding effect is further enhanced. Since the shield / acoustic resistance material 16 also has an effect as an acoustic resistance material, the acoustic characteristics of the headphones can be adjusted without providing a separate acoustic resistance material.

  In FIG. 1, a protector 8 is disposed in front of the diaphragm 6 so that the diaphragm 6 cannot be touched from the outside. The protector 8 has substantially the same shape as the diaphragm 6, and the outer peripheral edge is fixed to the front surface of the baffle plate 10 with a certain distance from the front surface of the diaphragm 6. The protector 8 is formed with an appropriate number of holes for passing the sound wave from the diaphragm 6. The protector 8 is made of resin, and a conductive layer is formed on the surface of the protector 8. The conductive layer of the protector 8 communicates with the conductive layer on the surface of the baffle plate 10. The baffle plate 10 and the protector 8 may be formed of resin as an integral part, and a conductive layer may be formed on the surface.

The electromagnetic wave that is about to enter from the front side of the headphone unit 1 is blocked by the conductive layer on the surface of the protector 8, and the generation of noise caused by this electromagnetic wave can be prevented. When the conductive layer of the protector 8 and the conductive layer on the surface of the baffle plate 10 pass through, the shielding effect can be further enhanced.
The headphones configured as described above are usually paired with a pair of headbands to form stereo headphones.

  Instead of the conductive layer formed on the surface of the protector 8 in the above embodiment, a shield / acoustic resistance material may be attached to the surface of the protector 8. Since this shield / acoustic resistance material is a member that may come into contact with the user's ear or the like, for example, a sponge-like shield / acoustic resistance material that does not impair the tactile sensation may be used. Further, if a conductive cloth or a conductive layer is formed on the inner and outer surfaces of the ear pad 13 that constitutes the front cavity when the headphones are used, the shield against the human body side can be ensured.

It is a longitudinal cross-sectional view which shows the Example of the headphones which concern on this invention. It is a longitudinal cross-sectional view which shows the example of the conventional headphones.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Headphone unit 2 Unit frame 3 Yoke 4 Magnet 5 Pole piece 6 Diaphragm 7 Voice coil 8 Protector 10 Baffle plate 11 Jetty 12 Circuit board 13 Ear pad 14 Housing 16 Shield and acoustic resistance material 22 Acoustic hole

Claims (7)

A headphone unit including a diaphragm driven by an audio signal and emitting a sound wave;
A circuit board having a hole disposed behind the headphone unit and communicating with an acoustic hole of the headphone unit;
A headphone comprising: a shield / acoustic resistance material disposed so as to cover the back of the headphone unit together with the circuit board.   The headphone according to claim 1, wherein the shield / acoustic resistance material is made of a conductive cloth.   The headphone according to claim 1, further comprising a resin baffle plate to which the headphone unit and the circuit board are fixed, and a conductive layer formed on a surface of the baffle plate.   The headphone according to claim 3, wherein the shield / acoustic resistance material is electrically connected to the conductive layer on the surface of the baffle plate.   The headphone according to claim 3, wherein a resin protector for protecting the diaphragm is disposed on the front side of the baffle plate, and a conductive layer is formed on a surface of the protector.   The headphone according to claim 5, wherein the conductive layer on the surface of the protector is electrically connected to the conductive layer on the surface of the baffle plate.   A noise canceling type headphone comprising a microphone for detecting environmental noise and a cancel signal generating circuit for canceling the environmental noise detected by the microphone, wherein the cancel signal generating circuit is mounted on a circuit board. The headphones according to any one of 1 to 6.

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