JP2010178006A - Dynamic headphone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress excessive magnitude (excessive displacement) of a diaphragm due to a fall shock without using a limit element such as a stopper contacting the diaphragm. <P>SOLUTION: The dynamic headphone includes a headphone unit 1 including a diaphragm 10 having a voice coil 13, a magnetic circuit portion 20 having a magnetic gap G, and a unit frame 30, and a headphone housing 40 surrounding the back surface side of the unit frame 30 and forming a first rear air chamber A1, wherein the unit frame 30 includes an opening portion 31 for communicating a second rear air chamber A2 formed between the diaphragm 10 and the unit frame 30 to the first rear air chamber A1. In the dynamic headphone, a reactive valve 50 for opening and closing the opening 31 portion in response to a pressure difference between the first rear air chamber A1 and the second rear air chamber A2 is provided on at least either surface of the unit frame 30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to dynamic headphones in which a diaphragm is driven by a voice coil. More specifically, the present invention relates to a technique for suppressing an excessive amplitude of a diaphragm due to a drop impact or the like.

  First, the configuration of the dynamic headphones will be schematically described with reference to FIG. The dynamic headphones include a headphone unit 1 as an electro-acoustic converter including a diaphragm 10, a magnetic circuit unit 20, and a unit frame 30.

  The diaphragm 10 includes a center dome 11 and a sub dome 12 as an elastic support part integrally provided around the center dome 11, and a voice col 13 is attached to the back side of the boundary between the center dome 11 and the sub dome 12. It has been.

  The magnetic circuit unit 20 includes a permanent magnet 21 formed in a disk shape and a yoke 22 formed in a cup shape. The permanent magnet 21 is magnetized in the thickness direction and disposed in the yoke 22. A pole piece 23 is provided on the permanent magnet 21, and a magnetic gap G is formed between the pole piece 23 and the yoke 22.

  The unit frame 30 is formed in a disk shape, and supports the magnetic circuit unit 20 at the center portion thereof. The diaphragm 10 is hermetically supported at the periphery of the sub-dome 12 with respect to the unit frame 30 so that the voice coll 13 can vibrate within the magnetic gap G.

  A baffle plate 35 is provided around the unit frame 30, a headphone housing 41 is attached to the back side (anti-vibration plate side) of the baffle plate 35, and the sound emission surface side (vibration plate side) of the baffle plate 35. An ear pad 42 is attached around the.

  The headphone housing 41 forms a rear air chamber A1 having a predetermined volume on the back side of the unit frame 30. Further, since the peripheral edge of the sub dome 12 is hermetically supported with respect to the unit frame 30, the rear air chamber A <b> 2 is also formed between the diaphragm 10 and the unit frame 30. In the following description, the rear air chamber A1 may be referred to as a first rear air chamber, and the rear air chamber A2 may be referred to as a second rear air chamber.

  The unit frame 30 is provided with a plurality of openings 31 for communicating the first rear air chamber A1 and the second rear air chamber A2, and an acoustic resistance material 32 is provided in each of the openings.

  When a voice signal is supplied to the voice coil 13 from a voice reproduction device (not shown) as a current, the diaphragm 10 vibrates and operates as a peaker, whereby sound is emitted from the headphone unit 1.

  At that time, the elasticity of the sub dome 12 is designed so that the diaphragm 10 does not come into contact with the magnetic circuit unit 20 and the voice coil 13 does not jump out of the magnetic gap G, and the headphone unit 1 is assembled.

  However, if an excessive amplitude occurs in the diaphragm 10, the diaphragm 10 collides with the magnetic circuit unit 20 as shown in FIG. 6, or the voice coil 13 jumps out of the magnetic gap G as shown in FIG. It may not return to the position.

  Excessive amplitude of the diaphragm 10 often occurs when an impact such as a drop impact is applied to the headphones, or when the ear pad 42 is pressed against the head in a sealed state.

  In addition, in the noise canceling type headphone which is equipped with an active circuit and reduces external sound, a microphone for detecting sound waves is provided in the vicinity of the headphone unit 1. For example, when the pressure applied to the microphone changes when the headphone is attached or detached, In order to cancel this pressure, a large signal may be applied to the voice coil 13 from the active circuit, which may cause the diaphragm 10 to be excessively displaced.

  Therefore, in the invention described in Patent Document 1, a restriction element (stopper) that limits the displacement of the diaphragm 10 to a certain range is provided in the headphone unit 1 to suppress an excessive displacement (excessive amplitude) of the diaphragm 10. Has been proposed.

However, the mass of the vibration system including the voice coil 13 is usually 0. If the volume of the first rear air chamber A1 is about 100 cc, for example, about several grams (about 0.13 g for a unit with a diameter of 40 mm), the mechanical impedance (stiffness) is 1.14 × 10 ⁶ [dyn / cm]. About small.

  Therefore, when receiving a drop impact or the like, or when a large signal is applied to the voice coil 13 from the active circuit, the diaphragm 10 is easily displaced to contact the limiting element, and when this contact is repeated at the same place, The diaphragm 10 and the voice coil 13 are deformed. In the worst case, a part of the deformed diaphragm 10 or the voice coil 13 may be gnawed in the magnetic gap G.

Japanese Patent No. 3268774

  Accordingly, an object of the present invention is to suppress an excessive amplitude (excessive displacement) of a diaphragm due to a drop impact or the like without using a limiting element such as a stopper that contacts the diaphragm in a dynamic headphone.

  In order to solve the above-described problems, the present invention includes a diaphragm to which a voice coil is attached, a magnetic circuit unit having a magnetic gap with respect to the voice coil, and a disk-shaped unit frame, and the magnetic circuit unit is a part of the unit frame. A headphone unit that is disposed in a central portion and whose periphery of the diaphragm is hermetically supported by the unit frame so that the voice coil can vibrate within the magnetic gap; and a rear side of the unit frame And a headphone housing that forms a first rear air chamber having a predetermined volume with the unit frame, the second rear air chamber being formed between the diaphragm and the unit frame on the unit frame. Headphones provided with an opening that communicates with the first rear air chamber In this case, at least one surface of the unit frame is provided with a responsive valve that opens and closes the opening in response to a pressure difference between the first rear air chamber and the second rear air chamber. It is characterized by that.

  As a preferred aspect of the present invention, the responsive valve is provided on both the back side and the diaphragm side of the unit frame.

  Moreover, as a preferable aspect of the present invention, the responsive valve has a tongue-like valve body made of a resin film attached to the unit frame through a spacer having a predetermined thickness on one end side thereof. A thin air layer resistance (acoustic resistance) is formed between the unit frame surfaces.

  As a preferred aspect of the present invention, the valve element does not respond to a pressure difference between the first rear air chamber and the second rear air chamber at least when the diaphragm is vibrated by energizing the voice coil. Has stiffness.

  As a preferred embodiment of the present invention, the valve body is made of a PET film having a thickness of 0.1 mm.

  Moreover, as a preferable aspect of the present invention, the volume of the second rear air chamber is 2 cc or less.

  Moreover, as a preferable aspect of the present invention, the volume of the first rear air chamber is 20 cc or more.

  According to the present invention, at least one surface of the unit frame is opened / closed in response to a pressure difference between the first rear air chamber and the second rear air chamber so as to communicate between the two rear air chambers. For example, when the pressure difference becomes a predetermined value or more due to a drop impact or the like, the reaction valve is closed and the second rear air chamber is sealed, so that it exceeds that of the diaphragm. The displacement of is suppressed.

  For example, if the responsive valve is provided on the back side of the unit frame, excessive displacement in the direction away from the unit frame of the diaphragm is prevented, and if the responsive valve is provided on the diaphragm side of the unit frame, Excessive displacement of the diaphragm toward the unit frame is prevented.

  According to the aspect in which the responsive valve is provided on both the back side and the diaphragm side of the unit frame, excessive displacement in both directions of the diaphragm is sealed.

  The responsive valve has a tongue-like valve body made of a resin film attached to the unit frame via a spacer having a predetermined thickness on one end side, and a thin air layer resistance ( According to the aspect which forms (acoustic resistance), the responsive valve itself can serve as an acoustic resistance material. Therefore, it is not necessary to separately provide an acoustic resistance material.

  According to an aspect in which the valve body has a stiffness that does not respond to a pressure difference between the first rear air chamber and the second rear air chamber at least when the diaphragm is vibrated by energizing the voice coil, as a speaker during normal use It can work normally and get good sound quality.

When the volume of the second rear air chamber (the rear air chamber of the diaphragm) is 2 cc or less, the mechanical impedance (stiffness) is 57 × 10 ⁶ [dyn / cm] or more, and an impact is applied compared to the case of 100 cc. The amplitude can be reduced to 1/50.

  As an example, when the elastic limit (maximum amplitude) of the diaphragm when there is no second rear air chamber (no load) is ± 2 mm, and the second rear air chamber is 2 cc or less, the diaphragm Is suppressed to about ± 0.04 mm. Further, since high stiffness acts on the entire diaphragm, stress does not concentrate on a part of the diaphragm.

  If the volume of the first rear air chamber (rear air chamber of the unit frame) is 20 cc or more, the first rear air chamber is connected via a thin air layer resistance by the valve body during normal speaker operation when the valve body is opened. Since the diaphragm operates with low stiffness, the sound quality does not deteriorate.

1 is a cross-sectional view showing the internal structure of a dynamic headphone according to the present invention. The expanded sectional view which shows the responsive valve applied to embodiment of this invention. Sectional drawing which shows the operation state of the responsive valve at the time of the excessive amplitude to the direction which approaches the unit frame of a diaphragm in this invention. FIG. 6 is a cross-sectional view showing the operating state of the responsive valve when the vibration plate has an excessive amplitude in a direction away from the unit frame. Sectional drawing which shows the internal structure of the dynamic headphones as a prior art example. Sectional drawing which shows the state which excessively displaced in the direction in which the diaphragm approaches a unit frame in the said prior art example. Sectional drawing which shows the state which excessively displaced in the direction which leaves | separates a diaphragm from the unit frame in the said prior art example.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 4, but the present invention is not limited to this. In the description of this embodiment, the same reference numerals are used for components that may be considered the same as or the same as those of the conventional example described with reference to FIG.

  First, referring to FIG. 1, the dynamic headphone of the present invention also includes a headphone unit 1 as an electro-acoustic converter including a diaphragm 10, a magnetic circuit unit 20, and a unit frame 30 as in the conventional example.

  The diaphragm 10 includes a center dome 11 and a sub dome 12 as an elastic support part integrally provided around the center dome 11, and a voice col 13 is attached to the back side of the boundary between the center dome 11 and the sub dome 12. It has been.

  The magnetic circuit unit 20 includes a permanent magnet 21 formed in a disk shape and a yoke 22 formed in a cup shape. The permanent magnet 21 is magnetized in the thickness direction and disposed in the yoke 22. A pole piece 23 is provided on the permanent magnet 21, and a magnetic gap G is formed between the pole piece 23 and the yoke 22.

  The unit frame 30 is formed in a disk shape, and supports the magnetic circuit unit 20 at the center portion thereof. The diaphragm 10 is hermetically supported at the periphery of the sub-dome 12 with respect to the unit frame 30 so that the voice coll 13 can vibrate within the magnetic gap G.

  A baffle plate 35 is provided around the unit frame 30, a headphone housing 41 is covered on the back side (anti-vibration plate side) of the baffle plate 35, and the sound emission surface side (vibration plate side) of the baffle plate 35. An ear pad 42 is attached around the.

  The headphone housing 41 forms a first rear air chamber (rear air chamber of the unit frame) A1 having a predetermined volume on the back side of the unit frame 30. Further, since the peripheral edge of the sub dome 12 is hermetically supported with respect to the unit frame 30, a second rear air chamber (rear plate air chamber) A 2 is also formed between the diaphragm 10 and the unit frame 30. Is done.

  The unit frame 30 is provided with a plurality of openings 31 for communicating the first rear air chamber A1 and the second rear air chamber A2, but in the present invention, an excessive amplitude ( In order to prevent an excessive displacement), the opening 31 is provided with a responsive valve 50 that opens and closes due to a pressure difference between the first rear air chamber A1 and the second rear air chamber A2.

  With reference to FIG. 2, the responsive valve 50 in this embodiment is attached to the unit frame 30 via a spacer 52 having one end side having a predetermined thickness, and the other end side is a resin film (or resin) having a free end. A tongue-like valve body 51 made of a sheet, a resin plate, or the like.

  The stiffness of the valve body 51 is designed so as not to respond to a pressure difference between the first rear air chamber A1 and the second rear air chamber A2 at least when the diaphragm 10 is vibrated by energizing the voice coil 13.

  Further, the valve body 51 is substantially parallel to the surface of the unit frame 32 in a natural state, and forms a predetermined thin air layer resistance (acoustic resistance) with the unit frame 32. The resistance value of the thin air layer resistance may be determined by the thickness of the spacer 52. For the valve body 51, a PET film having a thickness of 0.1 mm is suitable.

  In this embodiment, the valve bodies 51 are arranged on both the diaphragm 10 side (second rear air chamber A2 side) and the counter vibration plate 10 side (first rear air chamber A1 side) for each opening 31. ing.

  Next, the operation of the valve body 51 of the responsive valve 50 will be described with reference to FIGS. 3 and 4. For convenience of explanation, the valve body on the diaphragm 10 side is denoted by 51a, and the valve body on the anti-vibration plate 10 side is denoted by 51b. The pressure in the first rear air chamber A1 is set to P1, and the pressure P2 in the second rear air chamber A2.

  First, as shown in FIG. 3 due to a drop impact or the like, when the diaphragm 10 is displaced in a direction approaching the magnetic circuit unit 20, the pressure P2 in the second rear air chamber A2 is changed to the pressure in the first rear air chamber A1. Since it is higher than P1 (P2> P1), the valve body 51a on the diaphragm 10 side is bent to close the opening 31. Thereby, since the inside of the second rear air chamber A2 is almost sealed, the diaphragm 10 is difficult to move, and the collision of the diaphragm 10 with the magnetic circuit unit 20 is prevented.

  On the contrary, when the diaphragm 10 is displaced in a direction away from the magnetic circuit portion 20 side due to a drop impact or the like, the pressure P1 in the first rear air chamber A1 is changed to the second rear air chamber. Since the pressure P2 in A2 is higher (P1> P2), the valve body 51b on the side of the anti-vibration plate 10 bends and closes the opening 31. Thereby, since the inside of the second rear air chamber A2 is almost sealed, the diaphragm 10 is difficult to move, and the voice coil 13 is prevented from jumping out from the magnetic gap G.

  In this way, excessive displacement of the diaphragm 10 is prevented, but the volume of the second rear air chamber A2 (rear air chamber of the diaphragm 10) is preferably 2 cc or less.

That is, when the volume of the second rear air chamber A2 is 2 cc or less, the mechanical impedance (stiffness) is 57 × 10 ⁶ [dyn / cm] or more, and compared with the case of 100 cc, the diaphragm 10 when an impact is applied. Can be reduced to 1/50.

  As an example, when the second rear air chamber A is 2 cc or less assuming that the elastic limit (maximum amplitude) of the diaphragm 10 when the second rear air chamber A is not present (no load) is ± 2 mm. The amplitude of the diaphragm 10 is suppressed to about ± 0.04 mm.

  In addition, since high stiffness acts on the entire diaphragm 10, stress does not concentrate on a part of the diaphragm 10. In order to make the opening / closing operation of the valve body 51 more sensitive, the resistance value of the thin air layer resistance by the valve body 51 may be increased.

  When the diaphragm 10 is vibrated by energizing the voice coil 13 (when operating as a speaker), the valve body 51 is opened, and the first rear air chamber A1 (the rear air chamber of the unit frame 30) and the second rear air. The diaphragm 10 vibrates in a state where the chamber A2 (the rear air chamber of the diaphragm 10) communicates with the thin air layer resistance.

  In this case, if the volume of the first rear air chamber A1 is 20 cc or more, during the normal speaker operation in which the valve body 51 is opened, the first rear air chamber A1 has a thin air layer resistance through the valve body 51. Since the diaphragm 10 operates with low stiffness, the sound quality does not deteriorate. Therefore, the preferable volume of the first rear air chamber A1 is 20 cc or more.

  In the above-described embodiment, the valve bodies 51 are disposed on both the diaphragm 10 side (second rear air chamber A2 side) and the counter vibration plate 10 side (first rear air chamber A1 side) for each opening 31. However, as another mode, for example, the valve bodies 51 may be arranged on both sides of the opening 31 every other time, or, for example, for the odd-numbered openings 31, the valve bodies 51 are arranged on the diaphragm 10 side. The valve body 51 may be disposed on the anti-vibration plate 10 side with respect to the even-numbered openings 31.

  Further, although depending on the design of the vibration system including the voice coil 13, there is also an aspect in which the valve body 51 is arranged not on both surfaces of the opening 31 but on only one side thereof, that is, only on the diaphragm 10 side or only on the anti-vibration board 10 side. It is included in the present invention.

DESCRIPTION OF SYMBOLS 1 Headphone unit 10 Diaphragm 11 Center dome 12 Sub dome 13 Voice coil 20 Magnetic circuit part 21 Permanent magnet 22 Yoke 23 Pole piece 30 Unit frame 31 Opening part 35 Baffle plate 41 Headphone housing 42 Ear pad 50 Reaction valve 51 Valve body 52 Spacer A1 1st 1 Rear air chamber (rear air chamber of unit frame)
A2 Second rear air chamber (rear plate air chamber)
G Magnetic gap

Claims (7)

A diaphragm having a voice coil attached thereto, a magnetic circuit portion having a magnetic gap with respect to the voice coil, and a disk-shaped unit frame, wherein the magnetic circuit portion is disposed at a central portion of the unit frame, and the voice A headphone unit in which a peripheral edge of the diaphragm is hermetically supported by the unit frame so that a coil can vibrate within the magnetic gap;
A headphone housing that surrounds the back side of the unit frame and forms a first rear air chamber of a predetermined volume with the unit frame;
In the dynamic headphones in which the unit frame is provided with an opening that communicates the second rear air chamber formed between the diaphragm and the unit frame and the first rear air chamber.
At least one surface of the unit frame is provided with a responsive valve that opens and closes the opening in response to a pressure difference between the first rear air chamber and the second rear air chamber. Dynamic headphones.   The dynamic headphone according to claim 1, wherein the responsive valve is provided on both the back side and the diaphragm side of the unit frame.   The responsive valve has a tongue-like valve body made of a resin film attached to the unit frame via a spacer having a predetermined thickness at one end side, and a thin air gap between the unit frame and the surface of the unit frame. 3. The dynamic headphones according to claim 1, wherein a layer resistance is formed.   The valve body has a stiffness that does not respond to a pressure difference between the first rear air chamber and the second rear air chamber when the diaphragm is vibrated by energizing the voice coil. The dynamic headphones according to any one of 1 to 3.   5. The dynamic headphone according to claim 4, wherein the valve body is made of a PET film having a thickness of 0.1 mm.   6. The dynamic headphones according to claim 1, wherein the volume of the second rear air chamber is 2 cc or less.   The dynamic headphone according to any one of claims 1 to 6, wherein the volume of the first rear air chamber is 20 cc or more.

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