JP6149599B2 - earphone - Google Patents

Description

  The present invention relates to an earphone worn on a user's ear.

  An earphone that converts an audio signal into sound / soundwave and reproduces it is used by being worn on a user's ear. Since the earphone is small, it is difficult to sufficiently expand the sound reproduction frequency band.

  Patent Document 1 discloses a configuration in which a headphone support that is juxtaposed to an outer ear of a listener includes a first transducer for low-frequency reproduction and a second transducer for high-frequency reproduction as headphones. Here, the second transducer transmits sound through a porous earpiece provided at the ear canal entrance, and the first transducer transmits sound through a tube passing through the porous earpiece.

  In Patent Literature 2, the left and right electroacoustic transducers of the ear speaker device each have a housing, a speaker unit, and a tubular duct, and the tubular duct extends from the interior space of the housing to the vicinity of the user's outer ear entrance. The structure formed in the U shape which returns to a housing | casing part is disclosed. Here, it is stated that by providing a resistance member inside the tubular duct and providing a hole in front of it, it is possible to make the low sound of the sound radiated from the speaker unit reach the vicinity of the user's ear canal entrance. .

  Patent Document 3 discloses a configuration in which a baffle is fixed to an opening of an ear cup as an ear muff, and an ear pad is locked to the entire surface of the baffle via a breathable cushion material. Since it has an air layer, it is stated that the volume of this air layer can also be the volume of the front air chamber on the front side of the baffle. Further, in the third embodiment, a communication hole for acoustically communicating the rear air chamber, which is the inner space of the ear cup, and the front air chamber on the front side of the baffle is provided, and an acoustic resistance is provided on the rear air chamber side of the communication hole. A configuration for affixing a member is described.

Japanese Patent No. 4184283 JP 2009-260556 A JP 2011-15338 A

  In the earphone, in order to extend the sound reproduction band to a low frequency where the wavelength of the sound wave is long, for example, the acoustic tube (duct) is lengthened, but there is a problem that the size is increased.

  An object of the present invention is to provide an earphone that can be miniaturized while expanding a sound reproduction band to a low frequency.

  An earphone according to the present invention includes a driver that emits sound waves to the front and back surfaces of a diaphragm, a first space for defining a cavity space on the back surface side of the driver and guiding sound waves emitted forward to the user's ear canal side. A case having a sound hole and a second sound hole for guiding a sound wave radiated from the back surface to the ear canal side, the case having a duct communicating with the second sound hole, and a first disposed in the duct. 1 acoustic resistance member, and a second acoustic resistance member that covers the opening inside the case inside the duct.

  In the earphone according to the present invention, the filling mass per unit air volume of the first acoustic resistance member is larger than the filling mass per unit air volume of the second acoustic resistance member.

  In the earphone according to the present invention, the first acoustic resistance member and the second acoustic resistance member are in contact with each other without any gap at the opening inside the case.

  In the earphone according to the present invention, the duct has an ear canal insertion shape protruding from the case.

  In the earphone according to the present invention, the duct is sized to block a part of the ear canal, and the sound wave from the first sound hole is guided to a portion of the ear canal that is not blocked by the duct.

  In the earphone according to the present invention, the duct has a groove portion that defines a portion of the ear canal that is not blocked by the duct, in the ear canal insertion shape protruding from the case.

  The earphone according to the present invention transmits the sound wave radiated to the back surface of the driver via the first acoustic resistance member disposed inside the duct and the second acoustic resistance member covering the opening inside the case inside the duct. In other words, it is found that the sound reproduction band is widened on the low sound side compared with the case where only the first acoustic resistance member is used, or the sound reproduction band is widened on the low sound side compared with the case where only the second acoustic resistance member is used. It is based on that. In other words, even when the acoustic resistance member is disposed at the same length, the sound reproduction band is expanded on the lower sound side by combining the first acoustic resistance member and the second acoustic resistance member. Therefore, with the above configuration, it is possible to reduce the size while expanding the audio reproduction band to a low frequency.

  Further, in the earphone according to the present invention, the filling mass per unit air volume of the first acoustic resistance member arranged in the duct on the ear canal side is set to the unit mass of the second acoustic resistance member arranged on the cavity side. By making it larger than the filling mass of the sound, the sound reproduction band is expanded on the lower sound side. Therefore, by adopting such a configuration, it is possible to reduce the size while expanding the audio reproduction band.

  Further, in the earphone according to the present invention, the first acoustic resistance member and the second acoustic resistance member are in contact with each other without any gap at the opening inside the case, so that the sound reproduction band is widened on the bass side, and the middle The playback level of treble can also be increased. Therefore, by adopting such a configuration, it is possible to reduce the size while expanding the audio reproduction band.

  In the earphone according to the present invention, the duct has an ear canal insertion shape protruding from the case. Therefore, the earphone can be firmly placed on the user's ear.

  Further, in the earphone according to the present invention, the duct is sized to block a part of the ear canal, and the sound wave from the first sound hole is guided to the part of the ear canal that is not blocked by the duct. It is possible to reduce the size while expanding from high to low.

  Further, in the earphone according to the present invention, the duct has a groove portion that defines a portion of the ear canal that is not blocked by the duct, in the ear canal insertion shape protruding from the case. The groove portion defines a portion where the external auditory canal is not blocked by a duct, and a sound wave from the first sound hole is guided to the groove so that the sound reproduction band can be expanded from low to high, and the size can be reduced.

It is a figure which shows a mode that the earphone of embodiment which concerns on this invention is mounted | worn with a user's ear. It is sectional drawing of the earphone main body of embodiment which concerns on this invention. It is a figure which shows the state which removed the housing from the earphone main body of embodiment which concerns on this invention. (A) is a top view, (b) is a cross-sectional view, and (c) is a bottom view. It is a figure which shows the characteristic of embodiment which concerns on this invention, and the characteristic of Comparative Examples 1, 2, 3 about the sound pressure frequency characteristic of an earphone. It is a figure which shows the characteristic of embodiment which concerns on this invention, and the characteristic of Comparative Examples 1, 4, 5 about the sound pressure frequency characteristic of an earphone. It is a figure which shows the characteristic of embodiment which concerns on this invention, and the characteristic of Comparative Examples 1, 2, and 3 about the frequency characteristic of the phase difference of the sound wave radiated | emitted to the front direction and the back direction of the driver of an earphone, respectively.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. The dimensions, shapes, materials, and the like described below are examples for explanation, and can be appropriately changed according to the specifications of the earphone. Below, the same code | symbol is attached | subjected to the same element in all the drawings, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a diagram illustrating a state where the earphone 10 is worn on a user's ear. Here, although not a component of the earphone 10, the user's right ear 4 shown as (R), the left ear 6 shown as (L), and the respective external auditory canals 8 are illustrated. The earphone 10 includes a right earphone main body 12 for the right ear 4, a left earphone main body 14 for the left ear 6, a cable 16 connected to each of them, and a jack portion 18 connected to an audio device (not shown). It is comprised including. FIG. 1 shows a state in which the right earphone main body 12 is attached to the right ear 4, and the left earphone main body 14 shows a state before being attached to the left ear 6.

  Since the right earphone main body 12 and the left earphone main body 14 are the same in configuration except that they are bilaterally symmetric, the left earphone main body 14 will be described below. Hereinafter, the left earphone body 14 is simply referred to as the earphone body 14. In the earphone main body 14, a baffle 32, a housing 34, and a duct 36 protruding from the baffle 32 are integrally formed to form a case 30. The earphone main body 14 holds the baffle 32 and the housing 34 using an overhang called a tragus 7 and an antitragus 9 that surrounds the external ear canal 8 of the left ear 6 while pressing the cushion 38 against the left ear 6. The duct 36 is inserted into 8 and the left ear 6 is attached.

  The structure of the earphone main body 14 will be described in more detail with reference to FIGS. FIG. 2 is a cross-sectional view of the earphone main body 14. FIGS. 3A and 3B are views showing the case where the housing 34 is removed from the earphone main body 14, wherein FIG. 3A is a top view, FIG. 3B is a cross-sectional view, and FIG.

  The case 30 has a baffle 32 having a plane shape close to an elliptical shape as a member on the bottom surface side, and a housing 34 having a substantially triangular outer shape and a hollow inside disposed on the upper surface side of the baffle 32. The outer edge portion on the side and the outer edge portion on the bottom surface side of the housing 34 are combined and integrated. A duct 36 protrudes from the baffle 32. A cavity 31 that is an internal space is formed by the upper surface of the baffle 32, the driver 20, and the inner wall surface of the housing 34.

  The driver 20 disposed in the cavity 31 that is the internal space of the case 30 is a sounding body having a diaphragm that vibrates by an electric signal. The diaphragm is disposed substantially parallel to the surface of the baffle 32. Therefore, when the diaphragm vibrates, the air in front of the diaphragm vibrates and radiates sound waves forward, and the air on the back surface also vibrates and emits sound waves to the back surface. The housing 34 is provided with a drawing hole for drawing the cable 16 from the driver 20 to the outside.

  The baffle 32 constituting the case 30 is an elliptical plate-like member in which the driver 20 is disposed on one surface and the outer edge of the housing 34 is combined with the outer edge. The size of the ellipse is set based on the distance between the tragus of the left ear 6 and the tragus. The surface on the other side opposite to the side on which the driver 20 is attached is a front surface facing the ear canal 8 when the earphone 10 is worn on the user's left ear 6. The front surface has a gentle convex shape on the outer ear canal 8 side.

  The first sound hole 40 provided in the baffle 32 is a through hole that guides the sound wave 22 radiated forward from the diaphragm of the driver 20 to the ear canal 8 side, and one opening portion of the hole faces the diaphragm, and the other side. The side opening faces the ear canal 8 side. In the example of FIG. 3C, three first sound holes 40 are provided, but other numbers may be used.

  The second sound hole 42 provided in the baffle 32 is a through hole that guides the sound wave 24 radiated from the diaphragm of the driver 20 to the back surface to the ear canal 8 side. This through hole communicates with the through hole of the duct 36. The second sound hole 42 is a partially annular hole as shown by a broken line in FIG.

  The duct 36 is a pipe portion that protrudes from the baffle 32 toward the ear canal 8 and has a through hole that communicates with the second sound hole 42. The duct 36 is an acoustic tube that guides the sound wave 24 radiated to the back surface of the driver 20 through the second sound hole 42 communicating with the cavity 31 to the ear canal 8. The duct 36 has a partial annular shape having an outer diameter slightly smaller than the inner diameter of the hole of the ear canal 8. That is, the duct 36 has a groove portion 37 having a semicircular cross section on the center side of the partial annular shape. The through hole of the duct 36 has a partial annular shape having the same size as the second sound hole 42. The duct 36 is provided with an oblique angle from the front surface of the baffle 32 so that the earphone 10 is inserted into the external ear canal 8 when the earphone 10 is attached to the left ear 6. The protruding amount of the duct 36 is set in consideration of the wearing feeling, and is about 3 to 8 mm, for example.

  The outer shape of the duct 36 is not formed into a circular tube shape, and the groove portion 37 having a semicircular cross section is formed on the center side of the partially annular shape, so that when the duct 36 is inserted into the ear canal 8, Can be sized so as to block a part thereof. A sound wave from the first sound hole 40 is guided to a portion of the external auditory canal 8 that is not blocked by the duct 36. On the front surface of the baffle 32, a circular portion corresponding to the size of the external auditory canal 8 is provided as a contour portion 44 having a slightly different height from the periphery, and in this contour portion 44, the root portion of the duct 36, A first sound hole 40 is disposed.

  The cushion 38 is disposed along the outer side of the contour line 44 at an appropriate distance. The opening 35 provided on the front surface of the baffle 32 on the opposite side of the contour portion 44 across the cushion 38 is a sound wave radiated from the driver 20, and the first sound hole 40 and the second sound hole. This is to appropriately diffuse and radiate sound waves not guided to 42 to the outside. In the example of FIG. 3C, three open holes 35 are provided, but the number thereof may be other than this.

  As the baffle 32 constituting the case 30, the housing 34, and the duct 36 provided in the baffle 32, a resin material having an appropriate strength molded into a predetermined shape can be used. As the resin material, acrylonitrile butadiene styrene resin (ABS), polystyrene resin (PS), or polycarbonate resin (PC) can be used. The duct 36 may be formed separately from the baffle 32 and integrated by adhesion or the like.

  With the above configuration, sound waves from the back surface of the driver 20 are guided from the inside of the cavity 31 to the ear canal 8 side by the second sound hole 42 provided in the baffle 32 and the through hole of the duct 36 communicating with the second sound hole 42. A first acoustic resistance member 50 and a second acoustic resistance member 52 are provided in a path through which sound waves are guided from the back surface.

  The first acoustic resistance member 50 is disposed so as to fill a through hole inside the duct 36. As shown in FIG. 3A, the second acoustic resistance member 52 is disposed in the gap space 33 between the outer wall surface of the outer edge portion of the baffle 32 and the outer peripheral surface of the driver 20. The hole 42 is covered. Since the second sound hole 42 is also an opening inside the case of the duct 36, the second acoustic resistance member 52 is disposed so as to cover the opening inside the case of the duct 36.

  The acoustic resistance member is a member that increases acoustic resistance, which is resistance to sound waves, compared to air, and the larger the packing density of the members arranged at the air volume relative to the air volume of the path through which the sound waves are guided, Increases acoustic resistance. The packing density is the mass per unit air volume. When filling, the acoustic resistance is compressed, which is different from the density of the free state before compression. Here, the filling mass per unit air volume of the first acoustic resistance member 50 is set to be larger than the filling mass per unit air volume of the second acoustic resistance member 52. As the first acoustic resistance member 50 and the second acoustic resistance member 52, urethane resins, nonwoven fabrics, and the like having different densities in a free state are used.

As an example, as the first acoustic resistance member 50, a nonwoven fabric of 300 to 400 kg / m ³ and urethane foam are used as the density in the natural state. As the second acoustic resistance member 52, a foamed foam of 50 to 60 kg / m ³ is used as a density in a natural state. The first acoustic resistance member 50 is filled by being pushed into the through hole of the duct 36, and the filling mass per unit air volume at that time is about 1.1 to 1.5 times the density in the natural state. For example, 330 kg / m ³ to 600 kg / m ³ . The second acoustic resistance member 50 is filled by being pushed into the gap space 33 between the baffle 36 and the driver 20, and the filling mass per unit air volume at that time is about 1.5 to 2 of the density in the natural state. .5 times. For example, 75 kg / m ³ to 150 kg / m ³ . In addition, said material and a numerical value are the illustrations for description, Comprising: A material other than this and a numerical value may be sufficient.

  The first acoustic resistance member 50 and the second acoustic resistance member 52 are firmly pressed into each other so as to be in contact with each other without any gap at the upper surface side of the second sound hole 42, that is, the opening inside the case of the duct 36. Be placed. “To contact each other without a gap” means that an air-only layer is not formed at the boundary between the first acoustic resistance member 50 and the second acoustic resistance member 52 at least in the opening inside the case of the duct 36. , And the meaning. The reason for this is that when an air-only layer is formed at the boundary between the first acoustic resistance member 50 and the second acoustic resistance member 52, as will be described later, This is because the sound wave guided to the ear canal through the second sound hole 42 and the through hole of the duct 36 does not contribute to the improvement of the sound pressure frequency characteristics.

  Therefore, as shown in FIG. 3C, the first acoustic resistance member 50 is filled so as to protrude from the upper surface of the second sound hole 42 that is the case inner side opening in the duct 36. Further, as shown in FIG. 3A, the second acoustic resistance member 52 is wide enough to cover the second sound hole 42 which is the opening inside the case in the duct 36, and the baffle 36 and the driver. It fills over the wide range of the clearance space 33 between 20. In that case, it can design as a dimension which contacts the 1st acoustic resistance member 50 which protrudes rather than the upper surface of the 2nd sound hole 42. FIG.

  The effects of the earphone 10 having the above-described configuration will be described with reference to FIGS. 4 and 5 are diagrams in which the sound pressure frequency characteristics of the earphone 10 are compared with examples of other structures, where the horizontal axis represents frequency and the vertical axis represents sound pressure level (SPL). FIG. 6 is a diagram in which the phase difference frequency characteristics of the earphone 10 are compared with examples of other structures, where the horizontal axis represents frequency and the vertical axis represents phase difference. The phase difference here refers to the phase difference of the radiated sound wave from the back direction with reference to the radiated sound wave from the driver front direction.

  The frequency characteristic 60 in FIGS. 4 and 5 is the frequency characteristic of the earphone 10 of the present embodiment having the structure of FIGS. That is, it is a frequency characteristic when it has the duct 36 and the 1st acoustic resistance member 50 and the 2nd acoustic resistance member 52 are arrange | positioned as demonstrated in FIG. The frequency characteristic 62 in FIGS. 4 and 5 is the frequency characteristic of the earphone of Comparative Example 1 having a structure in which the duct 36 is not provided, and thus the first acoustic resistance member 50 and the second acoustic resistance member 52 are not provided. . As can be seen from FIGS. 4 and 5, compared with the frequency characteristic 62 of Comparative Example 1, the frequency characteristic 60 of the earphone 10 having the structure of FIGS. 1 to 3 has an improved sound pressure level in a low frequency band. Yes.

  In FIG. 4, the frequency characteristic 64 includes the duct 36, and the first acoustic resistance member 50 is filled in the duct 36, but the second acoustic resistance member 52 is not disposed. It is. The frequency characteristic 64 of the comparative example 2 has an improved sound pressure level in a lower frequency band than the frequency characteristic 62, but does not reach the frequency characteristic 60 of the earphone 10 having the structure shown in FIGS.

  In FIG. 4, the frequency characteristic 66 has a duct 36, and the duct 36 is not filled with the first acoustic resistance member 50 and remains a through hole, but the second acoustic resistance member 52 is a second sound hole. 42 is a frequency characteristic of Comparative Example 3 that sufficiently covers 42. The frequency characteristic 66 of Comparative Example 3 is almost the same as the frequency characteristic 62, and the sound pressure level in the low frequency band is not improved.

  In FIG. 5, the frequency characteristic 68 includes a duct 36, the first acoustic resistance member 50 is filled in the duct 36, and sufficiently covers the second sound hole 42 of the second acoustic resistance member 52. However, it is the frequency characteristic of the comparative example 4 in which there is a gap between the first acoustic resistance member 50 and the second acoustic resistance member 52 and an air layer is interposed. The frequency characteristic 68 of Comparative Example 4 has a lower sound pressure level in the lower frequency band than the frequency characteristic 64 of FIG. That is, when the duct 36 is filled with the first acoustic resistance member 50, the sound pressure level in the low frequency band is improved to some extent, but when the second acoustic resistance member 52 is further covered, By covering with the acoustic resistance member 52, the sound pressure level in the low frequency band deteriorates. That is, when the second acoustic resistance member 52 is covered with the first acoustic resistance member 50, it is important not to create a gap therebetween, and data indicating that an air layer gap is counterproductive. It is.

  In FIG. 5, the frequency characteristic 70 is the frequency characteristic of the comparative example 5 in which only the duct 36 is provided and neither the first acoustic resistance member 50 nor the second acoustic resistance member 52 is disposed. That is, the frequency characteristic 70 is a diagram showing the characteristics of a hollow acoustic tube. In the frequency characteristic 70 of Comparative Example 5, although the sound pressure level is improved in the high frequency band, the sound pressure level in the low frequency band is not improved.

  In FIG. 6, a frequency characteristic 61 shows the frequency characteristic of the phase difference of the earphone 10 of the present embodiment having the structure of FIGS. 1 to 3, and corresponds to the sound pressure frequency characteristic 60 of FIGS. It is a phase difference frequency characteristic. On the other hand, the frequency characteristic 63 is a frequency characteristic of the earphone of Comparative Example 1 having a structure in which the duct 36 is not provided, and thus the first acoustic resistance member 50 and the second acoustic resistance member 52 are not provided. It is a phase difference frequency characteristic corresponding to the sound pressure frequency characteristic 62 of FIG. The frequency characteristic 63 of Comparative Example 1 has a phase difference of about 180 degrees around the resonance frequency (about 400 Hz), and has a reverse phase relationship. On the other hand, the frequency characteristic 61 of the earphone 10 of the present embodiment having the structure of FIGS. 1 to 3 has a small absolute value of the phase difference from the low sound range to the high sound range, and also the phase difference in the low sound frequency band is The phase difference of the frequency characteristic 63 is almost the same value and shows a stable characteristic. Therefore, in the case of the present embodiment, there is no cancellation by the sound waves that are in the opposite phase relationship, so that the audio reproduction band is expanded to a lower frequency as shown in FIGS. be able to.

  In FIG. 6, the frequency characteristic 65 has a duct 36, and the first acoustic resistance member 50 is filled in the duct 36, but the phase difference of Comparative Example 2 in which the second acoustic resistance member 52 is not disposed. This is a phase difference frequency characteristic corresponding to the sound pressure frequency characteristic 64 of FIG. As shown in FIG. 6, the frequency characteristic 65 of the comparative example 2 improves the phase difference frequency characteristic in the vicinity of the resonance frequency with respect to the frequency characteristic 63, but is approximately equal to the phase difference of the frequency characteristic 63 in the low sound frequency band. A phase difference of 90 degrees occurs. Therefore, as shown in FIG. 4, the comparative example 2 does not have the sound pressure level at a low frequency in the case of this embodiment.

  In FIG. 6, the frequency characteristic 67 has a duct 36, and the duct 36 is not filled with the first acoustic resistance member 50 and remains a through hole, but the second acoustic resistance member 52 is a second sound hole. 42 is a phase difference frequency characteristic corresponding to the sound pressure frequency characteristic 66 of FIG. As shown in FIG. 6, the frequency characteristic 67 of Comparative Example 3 has a phase difference that changes depending on the frequency as compared with other frequency characteristics. Therefore, as shown in FIG. 4, the comparative example 3 does not have the sound pressure level at a low frequency in the case of this embodiment.

  For these reasons, in order to improve the bass characteristic, the duct 36 is provided, and the first acoustic resistance member 50 and the second acoustic resistance member 52 are arranged as described in FIG. Then, the filling mass per unit air volume of the first acoustic resistance member 50 is made larger than the filling mass per unit air volume of the second acoustic resistance member 52, and further, the first acoustic resistance member 50 and the second acoustic resistance member 50 It is preferable that the acoustic resistance members 52 be in contact with each other with no gap between the second sound holes 42 that are openings inside the case.

  In the above description, the duct 36 protrudes from the baffle 34. Alternatively, the duct 36 may be provided inside the cavity 31 without the baffle 34 protruding. In that case, the root of the duct 36 comes to the baffle 34 and the second sound hole 42 is provided on the root side of the duct. The case inner side opening is provided at the tip protruding into the cavity 31 of the duct 36 communicating with the second sound hole.

  4 Right ear, 6 Left ear, 7 Tragus, 8 External ear canal, 9 Pair of beads, 10 Earphone, 12 (Right) Earphone body, 14 (Left) Earphone body, 16 Cable, 18 Jack section, 20 Driver, 22 Radiating forward Sound wave, 24 sound wave radiated to the back, 30 case, 31 cavity, 32 baffle, 33 gap space, 34 housing, 35 open hole, 36 duct, 37 groove, 38 cushion, 40 first sound hole, 42 1st sound hole 2 sound holes, 44 contours, 50 first acoustic resistance member, 52 second acoustic resistance member, 60, 61, 62, 63, 64, 65, 66, 67, 68, 70 Frequency characteristics.

Claims (6)

A driver that emits sound waves to the front and back of the diaphragm;
A first sound hole for defining a cavity space on the back side of the driver and guiding the sound wave emitted forward to the ear canal side of the user and a sound hole for guiding the sound wave emitted on the back side to the ear canal side A case having two sound holes, wherein the case has a duct communicating with the second sound hole, a first acoustic resistance member disposed inside the duct, and an opening inside the case of the duct. A second acoustic resistance member covering the portion. The earphone according to claim 1,
An earphone in which a filling mass per unit air volume of the first acoustic resistance member is larger than a filling mass per unit air volume of the second acoustic resistance member. The earphone according to claim 1,
The earphone, wherein the first acoustic resistance member and the second acoustic resistance member are in contact with each other without any gap at the opening inside the case. The earphone according to claim 1,
The earphone has an ear canal insertion shape protruding from the case. The earphone according to claim 4,
The duct is sized so as to block a part of the ear canal, and the sound wave from the first sound hole is guided to a portion of the ear canal that is not blocked by the duct. The earphone according to claim 5,
The earphone has an earphone insertion shape that protrudes from the case, and a groove that defines a portion of the ear canal that is not blocked by the duct.

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