JP2018201182A - Electroacoustic conversion device - Google Patents

Abstract

To provide an electroacoustic conversion device which enables a user to select desired acoustic properties.SOLUTION: An electroacoustic conversion device includes a housing 40, a piezoelectric type sounder 32, and a movable member 70. The housing 40 has a sound guide passage 41. The piezoelectric type sounder 32 includes: a first diaphragm 321 having a peripheral edge part; a piezoelectric element 322 disposed on at least one surface of the first diaphragm 321; and one or multiple passages 330 provided in an area between the peripheral edge part and the piezoelectric element 322. The piezoelectric type sounder 32 partitions an interior of the housing 40 into a first space part and a second space part via the passage parts 330. The movable member 70 has a support surface supported by the peripheral edge part and is configured to be able to move the piezoelectric type sounder 32 relative to the housing 40.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electroacoustic transducer applicable to, for example, an earphone or a headphone, a portable information terminal, or the like.

  Piezoelectric sound generating elements are widely used as simple electroacoustic conversion means, and are frequently used, for example, as acoustic devices such as earphones or headphones, and also as speakers of portable information terminals. A piezoelectric sounding element typically has a configuration in which a piezoelectric element is bonded to one or both surfaces of a diaphragm (see, for example, Patent Document 1).

  On the other hand, Patent Document 2 describes a headphone that is provided with a dynamic driver and a piezoelectric driver, and that enables reproduction with a wide bandwidth by driving these two drivers in parallel. The piezoelectric driver is provided at the center of the inner surface of the front cover that closes the front surface of the dynamic driver and functions as a diaphragm, and is configured to function as a driver for the high frequency range.

  Patent Document 3 also describes an electroacoustic transducer that includes an electromagnetic sounding body and a piezoelectric sounding body and uses the piezoelectric sounding body for a high sound range. The electroacoustic transducer has a piezoelectric sounding body or a passage around it, and adjusts the sound wave output from the piezoelectric sounding body to a desired frequency characteristic by optimizing the size and number of the passages. There is a statement that you can.

JP2013-150305A Japanese Utility Model Publication No. 62-68400 Japanese Patent No. 5759641

  There are various types of sound reproduced by an earphone or the like to which an electroacoustic conversion device as in Patent Document 3 is applied, such as music or conference recording, and appropriate frequency characteristics differ depending on the type of sound and sound source. Also, the favorite sound quality varies from user to user.

  In view of the circumstances as described above, an object of the present invention is to provide an electroacoustic transducer capable of arbitrarily adjusting sound quality.

In order to achieve the above object, an electroacoustic transducer according to an embodiment of the present invention includes a housing, a piezoelectric sounding body, and a movable member.
The housing has a sound guide path.
The piezoelectric sounding body includes a first diaphragm having a peripheral portion, a piezoelectric element disposed on at least one surface of the first diaphragm, and a region between the peripheral portion and the piezoelectric element. One or a plurality of passage portions provided. The piezoelectric sounding body divides the interior of the housing into a first space portion and a second space portion via the passage portion.
The movable member has a support surface supported by the peripheral edge portion, and is configured to be able to move the piezoelectric sounding body relative to the casing.

  According to the electroacoustic transducer, since the relative position of the sound guide path and the passage portion can be changed by the movable member, the sound quality of the sound emitted from the sound guide path can be arbitrarily adjusted.

The movable member is typically configured to be able to rotate the first diaphragm about one axis with respect to the housing.
In this case, the sound guide path is arranged at a position eccentric with respect to the rotation center of the first diaphragm.

The said movable member may further have a protrusion part and a control part. The protruding portion is provided integrally with the support surface and protrudes outward of the housing. The restricting portion restricts a movement amount of the protruding portion.
Thereby, a movable member can be moved to arbitrary positions from the exterior of a housing | casing.

The electroacoustic transducer may further include an electromagnetic sounding body. The electromagnetic sounding body is disposed in the second space and includes a second diaphragm.
The electromagnetic sounding body may further include a guide portion that rotatably supports the piezoelectric sounding body.

  As described above, according to the present invention, the sound quality can be arbitrarily adjusted.

It is a schematic sectional side view which shows the structure of the electroacoustic transducer which concerns on one Embodiment of this invention. It is a schematic plan view of the piezoelectric sounding body in the electroacoustic transducer. It is a schematic plan view of the movable member in the electroacoustic transducer. It is a disassembled sectional side view of the sound generation unit containing the said movable member. It is a schematic plan view of the sound generation unit including the movable member. It is a figure which shows the relative positional relationship of the sound-guide path and the channel | path part on a diaphragm in the said electroacoustic transducer. It is a figure which shows the relative positional relationship of the sound-guide path and the channel | path part on a diaphragm in the said electroacoustic transducer. It is a schematic plan view of the piezoelectric sounding body in the electroacoustic transducer according to another embodiment of the present invention. It is an experimental result which shows an example of the sound pressure characteristic of the said piezoelectric type sounding body. It is an experimental result which shows an example of the sound pressure characteristic of the said electroacoustic transducer.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a schematic sectional side view showing a configuration of an earphone 100 as an electroacoustic transducer according to an embodiment of the present invention.
In the figure, an X axis, a Y axis, and a Z axis indicate triaxial directions orthogonal to each other.

[Overall configuration of earphone]
The earphone 100 includes an earphone main body 10, an earpiece 20, and a movable member 70. The earpiece 20 is attached to the sound guide path 41 of the earphone body 10 and is configured to be attachable to the user's ear.

  The earphone main body 10 includes a sound generation unit 30 and a housing 40 that houses the sound generation unit 30. The sounding unit 30 includes an electromagnetic sounding body 31 and a piezoelectric sounding body 32.

[Case]
The housing 40 has an internal space that accommodates the sound generation unit 30 and has a two-part structure that can be separated in the Z-axis direction. A sound guide path 41 that guides sound waves generated by the sound generation unit 30 to the outside is provided on one end surface (upper end surface in the drawing) 410 of the housing 40.

  The housing 40 is configured by a combination of a first housing portion 401 and a second housing portion 402. The first housing unit 401 has a housing space for housing the sound generation unit 30 therein. The second housing portion 402 has a sound guide path 41 and is combined with the first housing portion 401 in the Z-axis direction to cover the piezoelectric sounding body 32.

  The internal space of the housing 40 is partitioned by the piezoelectric sounding body 32 into a first space portion S1 and a second space portion S2. The first space portion S <b> 1 is a space portion that communicates with the sound guide path 41, and is formed between the piezoelectric sounding body 32 and the bottom portion 410 of the housing 40. An electromagnetic sounding body 31 is disposed in the second space S2. The first space portion S1 and the second space portion S2 communicate with each other via the passage portion 330 of the piezoelectric sounding body 32.

[Electromagnetic sound generator]
The electromagnetic sounding body 31 includes a dynamic speaker unit that functions as a woofer that reproduces a low frequency range. In the present embodiment, for example, a dynamic speaker that mainly generates sound waves of 7 kHz or less and includes a mechanical part 311 including a vibrating body (second diaphragm) such as a voice coil motor (electromagnetic coil), and the mechanical part 311 is vibrated. And a pedestal portion 312 that supports it. The structure of the mechanism part 311 of the electromagnetic sounding body 31 is not particularly limited.

  The electromagnetic sounding body 31 has a joint portion 313 that is fixed to a support portion 403 that constitutes the inner peripheral wall surface of the first housing portion 401. The joining portion 313 is provided on the bottom periphery of the pedestal portion 312 and joined to the upper surface of the support portion 403.

[Piezoelectric sounding body]
The piezoelectric sounding body 32 constitutes a speaker unit that functions as a tweeter that reproduces a high frequency range. In this embodiment, for example, the oscillation frequency is set so as to mainly generate sound waves of 7 kHz or higher. The piezoelectric sounding body 32 includes a diaphragm 321 (first diaphragm) and a piezoelectric element 322.

  The vibration plate 321 is made of a conductive material such as metal (for example, 42 alloy) or an insulating material such as resin (for example, liquid crystal polymer), and its planar shape is formed in a substantially circular shape. The “substantially circular” means not only a circular shape but also a substantially circular shape as described later. The outer diameter and thickness of the diaphragm 321 are not particularly limited, and are appropriately set according to the size of the housing 40, the frequency band of the reproduced sound wave, and the like. In this embodiment, a diaphragm having a diameter of about 8 to 12 mm and a thickness of about 0.2 mm is used.

  The diaphragm 321 may have a notch formed in a concave shape or a slit shape that is recessed from the outer periphery toward the inner periphery as necessary. Note that the planar shape of the diaphragm 321 is substantially circular if the rough shape is circular, even if it is not strictly circular due to the formation of the notch.

  In the present embodiment, the piezoelectric sounding body 32 has a unimorph structure in which a piezoelectric element 322 is joined to a surface of the diaphragm 321 facing the first space S1. The piezoelectric element 322 may be configured to be bonded to at least one of the surface facing the first space S1 and the surface facing the second space S2, and the configuration of the present embodiment is an example. The piezoelectric sounding body 32 may have a bimorph structure in which piezoelectric elements are bonded to both surfaces of the diaphragm 321.

  FIG. 2 is a plan view of the piezoelectric sounding body 32.

  As shown in FIG. 2, the planar shape of the piezoelectric element 322 is rectangular, and the central axis of the piezoelectric element 322 is typically disposed coaxially with the central axis C <b> 1 of the diaphragm 321. The center axis of the piezoelectric element 322 may be displaced by a predetermined amount, for example, in the X-axis direction from the center axis C1 of the diaphragm 321. That is, the piezoelectric element 322 may be disposed at a position eccentric with respect to the diaphragm 321. As a result, the vibration center of the diaphragm 321 is shifted to a position different from the center axis C 1, so that the vibration mode of the piezoelectric sounding body 32 is asymmetric with respect to the center axis C 1 of the diaphragm 321. Therefore, for example, by bringing the vibration center of the diaphragm 321 closer to the sound guide path 41, the sound pressure characteristics in the high sound range can be further improved.

  The diaphragm 321 has a plurality of passage portions 330 in its plane. These passage portions 330 constitute passage portions that penetrate the diaphragm 321 in the thickness direction, and include a first opening 331 and a second opening 332. The passage portion 330 allows the first space portion S1 and the second space portion S2 to communicate with each other inside the housing 40.

  The first opening 331 is configured by a plurality of circular holes provided in a region between the peripheral edge 321 c of the diaphragm 321 and the piezoelectric element 322. These first openings 331 are respectively provided at positions symmetrical with respect to the center axis C1 on the center line CL (a line parallel to the Y-axis direction passing through the center of the diaphragm 321). Each of the first openings 331 is formed by a round hole having the same diameter (for example, a diameter of about 1 mm), but is not limited thereto.

  The second opening 332 is provided between the peripheral edge 321c and the piezoelectric element 322, and is formed in a rectangular shape having a long side in the Y-axis direction. The second opening 332 is formed along the peripheral edge of the piezoelectric element 322, and a part of the second opening 332 is partially covered by the peripheral edge of the piezoelectric element 322. The second opening 332 has a function of preventing a short circuit between two external electrodes of the piezoelectric element 322 as described later, in addition to a function as a passage penetrating the front and back of the diaphragm 321.

  In the present embodiment, the piezoelectric sounding body 32 is configured to be rotatable around the central axis C <b> 1 with respect to the electromagnetic sounding body 31. As described above, the passage portion 330 is composed of the first and second openings 321 and 322 having different shapes, sizes, numbers, and the like, and these are regularly or irregularly arranged around the central axis C1. By arranging the diaphragms 321, the diaphragm 321 has an anisotropic structure in which the arrangement of the passage portions 330 is asymmetric with respect to the rotation direction.

  According to the configuration in which the arrangement of the passage portion 330 has anisotropy, the sound wave passage from the electromagnetic sounding body 31 to the sound guide path 41 is variously changed by the rotation of the piezoelectric sounding body 32 by the movable member 70. become. For example, the passage portion 330 that comes directly below the sound guide path 41 can be changed from the first opening portion 331 to the second opening portion 332 by rotating the piezoelectric sounding body 32. Since the first opening 331 and the second opening 332 have different opening shapes, this operation causes a change in sound quality. As described above, according to the present embodiment, the sound quality can be adjusted by the rotation operation.

[Movable member]
Next, details of the movable member 70 will be described. 3 is a schematic plan view of the movable member 70, FIG. 4 is an exploded side sectional view of the sound generation unit 30 including the movable member 70, and FIG. 5 is a schematic plan view of the sound generation unit 30 including the movable member 70.

  The movable member 70 has a mount ring 71 that supports the piezoelectric sounding body 32 so as to vibrate inside the housing 40. The mount ring 71 is formed in a ring shape (annular shape) as shown in FIG. The mount ring 71 is made of, for example, a synthetic resin material or a metal material. The mount ring 71 includes an operation unit 72, a support surface 75 that supports the peripheral portion 321 c of the diaphragm 321 of the piezoelectric sounding body 32, an outer peripheral surface 74 that faces the inner wall surface of the housing 40, and the electromagnetic sounding body 31. And an annular rib 76 engaged with the annular groove 77.

  The support surface 75 is joined to the peripheral portion 321c of the diaphragm 321 via an adhesive material layer (not shown) such as an annular adhesive tape. Thereby, since the diaphragm 321 is elastically supported with respect to the mount ring 71, the vibration fluctuation of the diaphragm 321 is suppressed, and the stable resonance operation of the diaphragm 321 is ensured.

  The annular rib 76 of the mount ring 71 and the annular groove 77 of the electromagnetic sounding body 31 constitute a guide portion 78 that rotatably supports the piezoelectric sounding body 32 (movable member 70). The annular rib 76 and the annular groove 77 are formed concentrically on the bottom surface of the mount ring 71 and the top surface of the electromagnetic sounding body 31, respectively. The second space S <b> 2 is defined by the engagement between the annular rib 76 and the annular groove 77 and the joining of the support surface 75 and the diaphragm 321. The first space portion S1 and the second space portion S2 communicate with each other via a passage portion 330 provided in the diaphragm 321 of the piezoelectric sounding body.

  The operation unit 72 is provided integrally with the mount ring 71 and is configured as a protruding portion that protrudes outward of the housing 40 along the X-axis direction. The piezoelectric sounding body 32 is configured to be rotatable with respect to the sound guide path 41 and the electromagnetic sounding body 31 from the outside of the housing 40 via the operation unit 72.

  The outer peripheral surface 74 of the mount ring 71 is in contact with the second housing portion 402 but is not fixed. When the piezoelectric sounding body 32 and the movable member 70 rotate, the mount ring 71 rotates (slids) while being in contact with the second casing portion 402 on the outer peripheral surface 74.

  The first housing 401 has an overhang 401 a that defines the operation range of the operation unit 72. The overhang portion 401 a has a fan-like plate shape that faces the operation portion 72 in the Z-axis direction with a predetermined gap, and is provided on the outer peripheral surface of the first housing portion 401 over the movable range of the operation portion 72. The overhanging portion 401 a is provided with an arcuate guide groove 79 that accommodates the regulation pin 73 that penetrates the operation portion 72. The restriction pin 73 and the guide groove 79 constitute a restriction part that restricts the movable range of the operation part 72 to a predetermined angle range. The restriction pin 73 may be configured to be able to fix the relative position between the operation unit 72 and the guide groove 79 at an arbitrary rotation position of the operation unit 72.

[Arrangement of sound guide path]
Next, the relationship between the arrangement of the sound guide path 41 and the rotation of the sound generation unit 30 and the diaphragm 321 will be described. FIGS. 6 and 7 are schematic plan views of the earphone 100 for explaining the positional relationship between the sound guide path 41 and the piezoelectric sounding body 32.

  FIG. 6 shows the relative positional relationship between the sound guide path 41 before rotation of the diaphragm 321 and the passage portion 330 on the diaphragm 321. When the operation unit 72 is in the position shown in FIG. 5, the sound guide path 41 is in a position as shown in FIG. On the other hand, FIG. 7 shows the sound guide path 41 after the rotation of the vibration plate 321 and the passage portion on the vibration plate 321 when the operation portion 72 is rotated about 45 degrees counterclockwise from the position of FIG. The relative positional relationship of 330 is shown.

  As described above, in this embodiment, the relative positional relationship between the sound guide path 41 and the passage portion 330 is variably adjusted by the movable member 70 that supports the piezoelectric sounding body 32. As a result, the path of the sound wave from the electromagnetic sounding body 31 to the sound guide path 41 changes variously due to the rotation of the piezoelectric sounding body 32 by the movable member 70. In the example shown in FIGS. 6 and 7, the passage portion 330 that comes directly below the sound guide path 41 can be changed from the first opening 331 to the second opening 332.

  In the present embodiment, the path of the sound wave from the electromagnetic sounding body 31 to the sound guide path 41 can be arbitrarily changed. In particular, the opening area of the passage portion 330 that affects the sound pressure level of the electromagnetic sounding body 31 can be changed. Therefore, according to the present embodiment, the sound quality can be arbitrarily adjusted by the user.

  As described above, according to the present embodiment, since the piezoelectric sounding body 32 is provided with the movable member 70 capable of moving relative to the electromagnetic sounding body 31 and the sound guide path 41, the piezoelectric sounding body is provided. The characteristics of the sound emitted from the sound guide path 41 can be arbitrarily adjusted according to the 32 rotational positions. Further, since the piezoelectric sounding body 32 is configured to be rotatable around the central axis C1, a movable mechanism of the piezoelectric sounding body 32 can be constructed without increasing the size of the housing 40.

<Second Embodiment>
FIG. 8 is a plan view of a piezoelectric sounding body in an electroacoustic transducer (earphone) according to a second embodiment of the present invention. In the present embodiment, only the configuration of the piezoelectric sounding body is different from that of the first embodiment. Hereinafter, the configuration different from the first embodiment will be mainly described, and the same configuration as the first embodiment will be denoted by the same reference numeral, and the description thereof will be omitted or simplified.

  The piezoelectric sounding body 52 of the present embodiment has two openings, a first opening 531 and a second opening 532 as a passage 530 provided in the plane of the circular diaphragm 521. The first and second openings 531 and 532 also have a function as an opening for preventing a short circuit. The first opening 531 is formed with an opening area larger than that of the second opening 532.

  The first opening 531 is formed in a substantially semicircular or semilunar shape in a region between the peripheral edge 521 c of the diaphragm 521 and one side of the piezoelectric element 322. The second opening 532 is formed in the same rectangular shape as the first opening 331 in the first embodiment.

  Four concave portions 521a and 521b are provided in the peripheral portion 521c of the diaphragm 521 at intervals of 90 °. These recesses 521 a and 521 b are used for positioning with respect to the housing 40. In particular, as shown in the drawing, one of the four recesses 521b has a shape different from that of the other three recesses 521a, so that a guide indicating the direction of the diaphragm 521 can be obtained. There is an advantage that assembly can be prevented.

  As in the first embodiment, the piezoelectric sounding body 52 is configured to be rotatable around the central axis C1 via a movable member 70 (not shown). As a result, the relative positions of the openings 531 and 532 of the piezoelectric sounding body 52 and the sound guide path 41 can be arbitrarily adjusted.

  Also in the electroacoustic transducer of the present embodiment configured as described above, the same effects as those of the first embodiment described above can be obtained. 9 and 10 show the relationship between the rotation angle of the piezoelectric sounding body 52 with respect to the sound guide path 41 and the sound pressure level of the sound emitted from the sound guide path 41. FIG. FIG. 9 shows one experimental result when only the piezoelectric sounding body 52 is driven, and FIG. 10 shows one experimental result when both the electromagnetic sounding body 31 and the piezoelectric sounding body 52 are driven.

  In this experimental example, as shown in FIG. 8, the angle at which the sound guide path 41 opposes the central portion of the first opening 531 in the Z-axis direction was set to 0 °. 8 and 9, the horizontal axis indicates the rotation angle of the piezoelectric sounding body 52 counterclockwise from the position of 0 ° shown in FIG. 8, and the vertical axis indicates the average sound pressure level at 9 kHz to 15 kHz. Show.

  As shown in FIGS. 9 and 10, the sound pressure level changes as the piezoelectric sounding body 52 rotates. This is because it depends on a change in the relative position between the passage portion 530 of the piezoelectric sounding body 52 and the sound guide path 41 as described above. In particular, it was confirmed that the sound pressure level at an angular position other than 0 ° is high.

  Particularly, as shown in FIG. 9, the sound pressure level when only the piezoelectric sounding body 52 is driven is significantly lower at 0 ° than at other angles. This is because a relatively large passage portion 530 (first opening portion 531) exists immediately below the sound guide path 41. In the angle range (for example, 90 ° to 150 °) where the passage portion 530 does not exist immediately below the sound guide path 41 or the overlap between the sound guide path 41 and the passage portion along the Z-axis direction is small (for example, 90 ° to 150 °), It was confirmed that sound can be obtained stably.

  On the other hand, as shown in FIG. 10, the sound pressure level when both the electromagnetic sounding body 31 and the piezoelectric sounding body 52 are driven is markedly lowered at a position of 90 °. This is because the passage portion 530 does not exist immediately below the sound guide path 41, so that the decrease in the sound pressure level in the low sound range (acoustic component derived from the electromagnetic sounding body 31) becomes larger than other angular positions.

  As described above, by changing the relative position between the sound guide path 41 and the passage portion 530, the sound pressure level of the low sound range, the high sound range, or both can be arbitrarily adjusted. Thereby, the acoustic characteristics can be optimized according to the type of the sound source and the user's preference.

  As mentioned above, although embodiment of this invention was described, this invention is not limited only to the above-mentioned embodiment, Of course, a various change can be added.

  For example, in the first embodiment described above, the allowable rotation angle range of the piezoelectric sounding body 32 with respect to the sound guide path 41 is about 45 °, but is not limited thereto, and is about 180 ° as in the second embodiment. It is good. Further, the number of passages 330 installed and the shape thereof are as shown in FIG. 2 and the like in the above embodiment, but are not limited to the illustrated example.

  The movable member is not limited to the case where the piezoelectric sounding body is configured to rotate with respect to the electromagnetic sounding body and the sound guide path, and both the electromagnetic sounding body and the piezoelectric sounding body (the entire sounding unit) can be used. You may comprise so that it may be rotationally moved with respect to a sound guide path.

  Alternatively, the movable member may be configured to be able to move the piezoelectric sounding body relative to the sound guide path in one axial direction (for example, in the X-axis direction in FIG. 1).

  In each of the above embodiments, the earphone has been described as an example of the electroacoustic conversion device. However, the present invention is not limited to this, and the present invention can also be applied to headphones, a stationary speaker, a speaker built in a portable information terminal, and the like. It is.

  Further, in the above embodiment, the electroacoustic transducer including the electromagnetic sounder and the piezoelectric sounder has been described as an example. However, the present invention is not limited thereto, and the electroacoustic transducer includes only the piezoelectric sounder. In addition, the present invention is applicable.

DESCRIPTION OF SYMBOLS 30 ... Sound generating unit 31 ... Electromagnetic sound-generating body 32, 52 ... Piezoelectric sound-generating body 321 ... Diaphragm 322 ... Piezoelectric element 330, 530 ... Channel | path part 40 ... Housing | casing 401 ... 1st housing | casing part 402 ... 2nd housing Body part 70 ... Moveable member 100 ... Earphone

Claims (6)

A housing having a sound guide path;
A first diaphragm having a peripheral edge, a piezoelectric element disposed on at least one surface of the first diaphragm, and one or a plurality of passages provided in a region between the peripheral edge and the piezoelectric element A piezoelectric sounding body that divides the interior of the housing into a first space portion and a second space portion that communicate with the sound guide path,
An electroacoustic transducer comprising: a movable member having a support surface supported by the peripheral edge portion and capable of moving the piezoelectric sounding body relative to the housing. The electroacoustic transducer according to claim 1,
The movable member is an electroacoustic transducer configured to be capable of rotating the first diaphragm about one axis with respect to the housing. The electroacoustic transducer according to claim 2,
The electroacoustic transducer is disposed at a position eccentric to the rotation center of the first diaphragm. The electroacoustic transducer according to any one of claims 1 to 3,
The movable member is
A protrusion provided integrally with the support surface and protruding outward of the housing;
An electroacoustic transducer further comprising: a restricting part that restricts a movement amount of the protruding part. The electroacoustic transducer according to any one of claims 1 to 4,
An electroacoustic transducer further comprising an electromagnetic sounding body disposed in the second space and including a second diaphragm. The electroacoustic transducer according to claim 5,
The electromagnetic sounding device further includes a guide portion that rotatably supports the piezoelectric sounding material.

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