JP4237424B2 - Electroacoustic transducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electroacoustic transducer.
[0002]
[Prior art]
As this type of electroacoustic transducer, for example, an electroacoustic transducer as disclosed in Japanese Patent Application Laid-Open No. 2000-69596 is known. The electroacoustic transducer disclosed in JP 2000-69596 A has a flexible earplug member and an electrical vibration conversion system (piezoelectric vibrator) that converts electrical energy into vibration energy. The vibration energy obtained by the electrical vibration conversion system is transmitted to the earplug member via the vibration transmission lever, and the earplug member is vibrated, thereby allowing the earplug member, the ear canal and the eardrum to be defined in the ear. The sound signal generated in the small air chamber is sensed.
[0003]
[Problems to be solved by the invention]
However, it has been newly found that the electroacoustic transducer having the above-described configuration has the following problems.
(1) Since the electric vibration conversion system is hollowly supported by the ear plug member via the lever, the force acting on the lever and the ear plug member from the electric vibration conversion system (driving force of the electric vibration conversion system) An equal force is applied as a reaction force to the mass of the electric vibration conversion system. In addition, mechanical resonance occurs due to the mass of the electric vibration conversion system, the lever, and the earplug member. As a result, the transmission efficiency of the air conduction sound generated in the small air chamber in the ear defined by the earplug member, the ear canal, and the eardrum is reduced, especially low frequency acoustic sensitivity (sound pressure). Becomes lower.
(2) A highly flexible earplug member is used, and the efficiency of vibration transmission inside the earplug member is poor.
(3) When an external force (pushing external force) is applied in the pushing direction with respect to the electric vibration conversion system with the electroacoustic transducer attached, the earplug member itself is pushed in, and the inside of the ear canal and the middle ear are damaged. There is a concern.
(4) If stress is applied to the electric vibration conversion system, the stress may concentrate on the joint between the electric vibration conversion system and the lever and breakage.
[0004]
The present invention has been made in view of the above points, and provides an electroacoustic transducer capable of improving acoustic characteristics, avoiding damage to the ear canal, the middle ear, and the like, and improving durability. Objective.
[0005]
[Means for Solving the Problems]
An electroacoustic transducer according to the present invention includes a drive unit that converts an electrical signal into mechanical vibration, a vibration transmission unit that transmits the mechanical vibration converted by the drive unit, and a mechanical vibration transmitted by the vibration transmission unit. It has an acoustic radiation part that radiates as vibration, a first support part that supports the driving part on the inner wall of the ear canal, and a second support part that supports the acoustic radiation part on the inner wall of the ear canal.
[0006]
In the electroacoustic transducer according to the present invention, the drive unit that converts an electrical signal into mechanical vibration is supported by the inner wall of the ear canal by the first support unit, and the machine is transmitted from the drive unit by the vibration transmission unit by the second support unit. An acoustic radiation portion that radiates vibration as acoustic vibration is supported by the inner wall of the ear canal. Thereby, the fall of the transmission efficiency below a specific frequency in the air conduction sound generated in the small space formed between the acoustic radiation part and the eardrum is suppressed, and the low frequency acoustic sensitivity (sound pressure) is improved.
[0007]
In the electroacoustic transducer according to the present invention, since the drive unit is supported by the inner wall of the ear canal by the first support unit, a part of the mechanical vibration generated by the drive unit is transmitted through the first support unit. Will reach the inner ear. Thereby, the low frequency sound volume, high frequency sound quality, etc. on hearing can be improved.
[0008]
In the electroacoustic transducer according to the present invention, even when an external force (pushing external force) is applied in the pushing direction to the drive unit with the electroacoustic transducer attached, the drive unit is supported by the first support portion on the inner wall of the ear canal. Therefore, the sound radiating portion is not pushed excessively, and damage to the ear canal, the middle ear, and the like can be avoided. In addition, since the electroacoustic transducer is supported by the first support portion and the second support portion, even if stress is applied to the drive portion, stress concentration at the connection portion between the drive portion and the vibration transmission portion is reduced. And durability can be improved.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of an electroacoustic transducer according to the present invention will be described in detail with reference to the drawings.
[0010]
First, the configuration of the electroacoustic transducer 1 will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing the structure of an electroacoustic transducer according to an embodiment of the present invention.
[0011]
The electroacoustic transducer 1 includes a drive unit 11, a vibration transmission unit 21, an acoustic radiation unit 31, a first support unit 41, and a second support unit 51.
[0012]
The drive unit 11 converts an electrical signal into mechanical vibration, and an electromagnetic transducer is used. The drive unit 11 includes a case 12, a pole piece 13, a coil 14, a magnet 15, a diaphragm 16, and the like.
[0013]
The case 12 is formed of a cylindrical metal member (for example, permalloy or the like) having a bottom surface portion 12a used as a base portion at one end and an opening at the other end. A gripping portion 17 made of a rubber material or the like is fixed to the outer surface side of the bottom surface portion 12a of the case 12.
[0014]
The pole piece 13 is placed and fixed at the center position of the inner surface of the bottom surface 12 a of the case 12. The pole piece 13 is made of a substantially cylindrical metal member (for example, permalloy).
[0015]
The coil 14 is configured by winding a conducting wire, and is disposed on the outer peripheral side of the pole piece 13. The coil 14 is fixed to the bottom surface portion 12a of the case 12 with an adhesive or the like.
[0016]
The magnet 15 is made of, for example, an annular plastic magnet, and is arranged on the outer peripheral side of the coil 14 with a predetermined gap between the magnet 15 and the coil 14. The magnet 15 is placed in contact with the bottom surface portion 12 a of the case 12.
[0017]
The diaphragm 16 (also referred to as a resonance plate or an elastic plate) is disposed on the opening side of the case 12. In the present embodiment, the case 12 (cylindrical portion) also functions as a support member that supports the diaphragm 16. A magnetic piece 18 as an additional mass is provided at the center of the diaphragm 16. The diaphragm 16 is in an attracted state by the action of the static magnetic field of the magnet 15 and is attracted to the magnet 15 side to be in a fixed state.
[0018]
In the drive unit 11 configured as described above, the bottom surface portion 12a of the case 12, the pole piece 13, the diaphragm 16 and the magnet 15 constitute a magnetic circuit, and a static magnetic field by the magnet 15 acts on the diaphragm 16. The magnetized diaphragm 16 is attracted to the iron core side. The magnet 15 acts as a bias magnetic field on the diaphragm 16.
[0019]
When an electric signal such as an alternating current or a pulse is applied to the drive unit 11 (coil 14) with respect to the magnetic field in one direction formed by such a static magnetic field, the signal current flows through the coil 14 and the electric signal is transmitted to the pole piece 13. An oscillating magnetic field corresponding to The diaphragm 16 swings away from the pole piece 13 in a section in which the direction of the oscillating magnetic field is opposite to the static magnetic field of the magnet 15, and is attracted to the pole piece 13 in a section in the same direction as the static magnetic field. Such mechanical motion depends on the frequency of the electrical signal, and as a result, the diaphragm 16 vibrates and mechanical vibration is generated.
[0020]
The vibration transmitting unit 21 transmits the mechanical vibration converted by the driving unit 11 to the acoustic radiation unit 31 and is made of a substantially columnar metal (for example, iron) or resin member. One end of the vibration transmitting unit 21 is bonded to the diaphragm 16 (magnetic piece 18) by bonding or the like, and the other end is bonded to the acoustic radiation unit 31 by bonding or the like.
[0021]
The acoustic radiation unit 31 radiates the mechanical vibration transmitted by the vibration transmission unit 21 as acoustic vibration, and is made of a material such as cushion foam. The acoustic radiating unit 31 vibrates in response to the electric signal input to the driving unit 11, and radiates acoustic vibrations in a small space 65 defined by the acoustic radiating unit 31, the human ear canal 61 and the eardrum 63. To do. This acoustic vibration excites the eardrum 63 so that a human senses it as sound. The acoustic radiation unit 31 also functions as a partition wall that defines the small space 65 with the ear canal 61 and the eardrum 63.
[0022]
The first support portion 41 is for supporting the driving portion 11 on the inner wall of the ear canal 61 and is made of a synthetic resin (for example, silicone resin) having a hardness that does not damage the ear canal 61. The first support portion 41 is provided over the entire circumference of the opening of the case 12. In addition, the 1st support part 41 does not need to be provided over the perimeter of the opening part of case 12, and should just be provided in at least several places.
[0023]
The 2nd support part 51 is for supporting the acoustic radiation | emission part 31 to the inner wall of the ear canal 61, and consists of materials, such as cushion foam. In this embodiment, the acoustic radiation part 31 and the 2nd support part 51 are integrally formed by one member (cushion foam). As shown in FIG. 1, the member in which the acoustic radiation portion 31 and the second support portion 51 are integrally formed has a dome shape, and the second support portion 51 is at the end portion of the dome-shaped member. Will be located. Further, the other end of the vibration transmitting portion 21 is joined to the top of a member having a dome shape.
[0024]
In the present embodiment, the first support portion 41 is provided by applying and curing a silicone resin adhesive so as to be in contact with the second support portion 51 over the entire circumference of the opening of the case 12. The drive unit 11 (case 12) and the second support unit 51 are integrated by a first support unit 41. Thus, the acoustic radiation part 31 is connected to the case 12 via the second support part 51 and the first support part 41, so that the movement of the diaphragm 16 in the direction away from the pole piece 13 is restricted. Further, the first support part 41 and the second support part 51 are arranged at substantially the same position, and the support position of the driving part 11 by the first support part 41 and the support of the acoustic radiation part 31 by the second support part 51. The position is almost the same.
[0025]
From the above, in the electroacoustic transducer 1 of the present embodiment, the drive unit 11 that converts an electrical signal into mechanical vibration is supported on the inner wall of the ear canal 61 by the first support unit 41, and the second support unit 51 An acoustic radiation unit 31 that radiates mechanical vibration transmitted from the drive unit 11 by the vibration transmission unit 21 as acoustic vibration is supported by the inner wall of the ear canal 61. Thereby, the fall of the transmission efficiency below a specific frequency in the air conduction sound which generate | occur | produces in the small space 65 formed between the acoustic radiation part 31 and the eardrum 63 is suppressed, and the low frequency acoustic sensitivity of the electroacoustic transducer 1 ( Sound pressure) is improved.
[0026]
Moreover, in the electroacoustic transducer 1 of this embodiment, since the drive part 11 is supported by the inner wall of the ear canal 61 by the 1st support part 41, a part of mechanical vibration which generate | occur | produces in the drive part 11 is 1st. The inner ear is reached by bone conduction through the support portion 41. Thereby, the low frequency sound volume, high frequency sound quality, etc. on the audibility of the electroacoustic transducer 1 can be improved.
[0027]
And in the electroacoustic transducer 1 of this embodiment, even if external force (pushing external force) is added to the drive part 11 with the electroacoustic transducer 1 mounted | worn with the pushing direction, the drive part 11 is 1st. Since it is supported by the inner wall of the external auditory canal 61 by the support part 41, the acoustic radiating part 31 is not pushed excessively, and damages in the external auditory canal 61 and the middle ear can be avoided. Further, since the electroacoustic transducer 1 is supported by the first support portion 41 and the second support portion 51, even if stress is applied to the drive portion 11, the drive portion 11 (the diaphragm 16), the vibration transmission portion 21, and the like. As a result, stress concentration at the connection portion is reduced, and durability can be improved.
[0028]
In the electroacoustic transducer of the present invention, a test was performed to confirm the low-frequency acoustic sensitivity improvement effect obtained by supporting the drive unit on the inner wall of the ear canal with the first support unit. The results are shown in FIGS. FIG. 2 is a diagram relating to the frequency characteristics of the example according to the electroacoustic transducer of the present invention, and FIG. 3 is a diagram relating to the frequency characteristics of the comparative example. In addition, the thing of embodiment mentioned above was used as an Example by this invention. On the other hand, the comparative example does not have the first support portion, that is, the drive portion is hollowly supported by the second support portion via the acoustic radiation portion and the vibration transmission portion.
[0029]
The measurement method of the frequency characteristic is as follows in both the example and the comparative example. In order to simulate the wearing state in the real ear, as shown in FIG. 4, a silicone artificial ear 101 using a replica of an auricle is used, and an electroacoustic transducer is attached to the artificial ear 101 to obtain frequency characteristics. It was measured. The entrance portion of the ear canal 103 has a tapered shape, and a 1/4 inch condenser microphone (“UC-14” manufactured by Rion Co., Ltd.) 105 is attached to the eardrum position. The inner diameter a of the ear canal 103 is set to 6 mm, and the total length b of the ear canal 103 is set to 28 mm. The length c of the linear portion in the ear canal 103 is set to 20 mm.
[0030]
The frequency characteristic is measured by an acoustic measurement system using an M-sequence signal (“CTX1010” manufactured by Coretex Corporation). Sensitivity is applied by applying a 1 kHz sine wave to the electroacoustic transducer so that the input voltage is 1 mW, and the sound pressure level in the small space (defined by the electroacoustic transducer, the external auditory canal 103 and the condenser microphone 105) It is measured by a precision sound level meter ("NA-54A" manufactured by Lion Co., Ltd.) connected to the microphone 105.
[0031]
As can be seen from FIGS. 2 and 3, it can be seen that the embodiment of the present invention improves the low-frequency acoustic sensitivity and suppresses the resonance of the electroacoustic transducer. In particular, it can be seen that the improvement at 2 kHz or less is remarkable. The sensitivity at 1 kHz of the example is 91 dB (1 mW input), and the sensitivity at 1 kHz of the comparative example is 97 dB (1 mW input).
[0032]
The present invention is not limited to the embodiment described above. For example, in the present embodiment, an electromagnetic transducer is used as the drive unit 11, but other types of transducers may be used without limitation to this as long as the electrical signal is converted into mechanical vibration. Also good.
[0033]
Further, in the present embodiment, the support position of the driving unit 11 by the first support part 41 and the support position of the acoustic radiation part 31 by the second support part 51 are substantially the same, but not limited thereto, These positions may be different. Moreover, you may make it form the 1st support part 41 and the 2nd support part 51 by an integral member.
[0034]
In the present embodiment, the acoustic radiation portion 31 and the second support portion 51 are integrally formed by one member. However, the present invention is not limited to this, and the acoustic radiation portion 31 and the second support portion 51 may be configured by separate members. . When the acoustic radiating unit 31 and the second support unit 51 are configured by separate members, the hardness of the acoustic radiating unit 31 is preferably higher than the hardness of the second support unit 51. Thereby, the deterioration of the efficiency of the vibration transmission in the acoustic radiation part 31 can be suppressed.
[0035]
In order to appropriately support the drive unit 11 having a large mass and improve the acoustic characteristics, it is preferable to set the hardness of the first support part 41 to be equal to or higher than the hardness of the second support part 51.
[0036]
【The invention's effect】
As described above in detail, in the present invention, the drive unit that converts an electrical signal into mechanical vibration is supported by the inner wall of the ear canal and the second support unit transmits vibration from the drive unit. An acoustic radiation portion that radiates mechanical vibration transmitted by the portion as acoustic vibration is supported by the inner wall of the ear canal. Thereby, the fall of the transmission efficiency below a specific frequency in the air conduction sound generated in the small space formed between the acoustic radiation part and the eardrum is suppressed, and the low frequency acoustic sensitivity (sound pressure) is improved. In the present invention, since the drive unit is supported on the inner wall of the external auditory canal by the first support unit, a part of the mechanical vibration generated in the drive unit reaches the inner ear by bone conduction. The low frequency volume, high frequency sound quality, etc. can be improved.
[0037]
And in this invention, since not only an acoustic radiation | emission part but a drive part is also supported by the inner wall of an external auditory canal, external force (push-in external force) in the pushing direction with respect to a drive part in the state which mounted | worn with the electroacoustic transducer Even if is added, the acoustic radiation portion is not excessively pushed, and damage to the ear canal, the middle ear, etc. can be avoided. Moreover, even if stress is applied to the electroacoustic transducer, stress concentration at the connecting portion between the drive unit and the vibration transmitting unit is alleviated, and durability can be improved.
[0038]
As a result, according to the present invention, it is possible to provide an electroacoustic transducer capable of improving acoustic characteristics, avoiding damage in the ear canal, the middle ear, and the like and improving durability.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a structure of an electroacoustic transducer according to an embodiment of the present invention.
FIG. 2 is a diagram relating to frequency characteristics of an embodiment of the electroacoustic transducer according to the present invention, showing the relationship between frequency and sound pressure level.
FIG. 3 is a diagram relating to frequency characteristics of a comparative example, showing the relationship between frequency and sound pressure level.
FIG. 4 is a schematic cross-sectional view showing the structure of an artificial ear.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electroacoustic transducer, 11 ... Drive part, 12 ... Case, 12a ... Bottom part, 13 ... Pole piece, 14 ... Coil, 15 ... Magnet, 16 ... Diaphragm, 17 ... Gripping part, 18 ... Magnetic piece, 21 DESCRIPTION OF SYMBOLS ... Vibration transmission part, 31 ... Sound emission part, 41 ... 1st support part, 51 ... 2nd support part, 61 ... Ear canal, 63 ... Tympanic membrane, 65 ... Small space, 101 ... Artificial ear, 103 ... Ear canal, 105 ... Condenser Microphone.

Claims (3)

A drive that converts electrical signals into mechanical vibrations;
A vibration transmission unit that transmits the mechanical vibration converted by the driving unit;
An acoustic radiation unit that radiates the mechanical vibration transmitted by the vibration transmission unit as an acoustic vibration; and
A first support part for supporting the drive part on the inner wall of the ear canal;
An electroacoustic transducer , comprising: a second support portion that contacts the inner wall of the ear canal in order to support the acoustic radiation portion.   The electroacoustic transducer according to claim 1, wherein the acoustic radiation portion and the second support portion are integrally formed by a single member. The first support part is provided in the driving part so as to come into contact with the second support part,
The electroacoustic transducer according to claim 1, wherein the driving unit and the second support unit are integrated via the first support unit.

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