阅读说明：本技术 无线耳机 (Wireless earphone ) 是由 小泽博道 于 2018-07-13 设计创作，主要内容包括：本发明提供一种无线耳机,其既能够实现壳体的小型化,又能够抑制因配置电池、电路板等电气元件而对电声换能器的音质产生的影响。该无线耳机的特征在于,具有：电声换能器(14),其输出与来自声源(S)的音频信号对应的声波；接收电路(151),其经由无线通信电路接收来自声源(S)的音频信号；电路板(15),其安装有接收电路(151)；以及壳体(11),其容纳电路板(15)和电声换能器(14)。壳体(11)具备：第1壳体(11A),其容纳电声换能器(14)；以及第2壳体(11B),其容纳电路板(15)。(The invention provides a wireless earphone which can realize the miniaturization of a shell and can restrain the influence on the sound quality of an electroacoustic transducer caused by arranging electric elements such as a battery and a circuit board. The wireless headset is characterized by comprising: an electroacoustic transducer (14) that outputs a sound wave corresponding to an audio signal from a sound source (S); a receiving circuit (151) that receives an audio signal from a sound source (S) via a wireless communication circuit; a circuit board (15) on which a receiving circuit (151) is mounted; and a housing (11) that houses the circuit board (15) and the electroacoustic transducer (14). The housing (11) is provided with: a 1 st housing (11A) that houses an electroacoustic transducer (14); and a 2 nd housing (11B) that houses the circuit board (15).)

1. A wireless headset, comprising:

an electroacoustic transducer that outputs a sound wave corresponding to the audio signal from a sound source;

a receiving circuit that receives an audio signal from the sound source via a wireless communication circuit;

a circuit board on which the receiving circuit is mounted; and

a housing containing the circuit board and the electroacoustic transducer,

the housing includes:

a 1 st housing accommodating the electroacoustic transducer; and

a 2 nd housing accommodating the circuit board.

2. The wireless headset of claim 1,

comprises a sound guide tube having an internal space through which the sound wave passes,

the 1 st housing includes a 1 st space, and the 1 st space communicates with the internal space.

3. The wireless headset of claim 2,

the 1 st housing is engaged with the 2 nd housing,

the 2 nd housing includes a 2 nd space, and the 2 nd space communicates with the 1 st space.

4. The wireless headset of claim 3,

the 1 st space is divided by the electroacoustic transducer into:

a front space communicating with the inner space; and

a rear space located on the 2 nd space side.

5. The wireless headset of claim 3,

the 1 st housing includes:

1, a shell; and

a 2 nd housing engaged with the 1 st housing,

the 2 nd housing includes:

the 2 nd housing; and

a 3 rd housing engaged with the 2 nd housing.

6. The wireless headset of claim 5,

the 1 st housing is provided with the sound guide tube,

the 1 st shell and the sound guide pipe are integrally formed.

7. The wireless headset of claim 5,

the 1 st shell and the sound guide pipe are formed in a split way,

the 1 st housing is engaged with the sound tube.

8. The wireless headset of claim 5,

the 2 nd housing includes a communication hole that communicates the 1 st space and the 2 nd space.

9. The wireless headset of claim 5,

the 2 nd shell is provided with a contraction part,

when the wireless earphone is worn on the ear of a user, one part of the contraction part is supported on the antitragus of the ear.

10. The wireless headset of claim 8,

the electroacoustic transducer is connected to the circuit board via a signal line inserted through the communication hole.

11. The wireless headset of claim 10,

the communication hole through which the signal line is inserted is closed.

12. The wireless headset of claim 1,

when the 1 st shell is arranged in the concha cavity, at least one part of the 2 nd shell is exposed outside the concha cavity.

13. The wireless headset of claim 1,

a battery for supplying power to the receiving circuit,

the battery is accommodated in the 2 nd case.

Technical Field

The invention relates to a wireless earphone.

Background

As one type of earphone, an in-canal type earphone (hereinafter, simply referred to as "earphone") is known. In general, a headphone has a pair of right and left playback units.

Each of the playback units includes: casing, electroacoustic transducer, sound guide pipe, earphone, patchcord. The housing has an internal space inside thereof, in which the electroacoustic transducer is accommodated. The electroacoustic transducer outputs a sound wave corresponding to an audio signal from a sound source such as a portable music player. When the earphone is worn on the ear of the user (hereinafter, simply referred to as "when the earphone is worn"), all or a part of the housing is disposed in the concha cavity of the user. The inner space of the housing is divided by the electroacoustic transducer into: a space (front space) in front of the electroacoustic transducer (in the direction of the user's head side when the headset is worn), and a space (rear space) behind the electroacoustic transducer (in the direction opposite to the direction of the user's head side when the headset is worn). The sound guide tube is mounted on the housing. When the earphone is used, the sound guide tube guides the sound waves from the electroacoustic transducer to a space in the external auditory canal of the user. The earphone is arranged on the sound guide tube. When the earphone is worn, the earphone can be clung to the inner wall of the external auditory canal of a user. As a result, the space in the external auditory canal communicates with the front space via the sound guide tube.

The cord connects the electroacoustic transducer and the sound source, and transmits an audio signal from the sound source to the electroacoustic transducer. The cord is provided with: an audio signal is guided to a core wire of the electroacoustic transducer and a cover film protecting the core wire.

In recent years, an earphone in which a housing is reduced by disposing an electroacoustic transducer inside a sound guide tube has been proposed (for example, see patent document 1).

Disclosure of Invention

Problems to be solved by the invention

In the earphone disclosed in patent document 1, since the electroacoustic transducer is disposed inside the sound guide tube, the size of the electroacoustic transducer is limited to the extent of being accommodated in the inner diameter of the sound guide tube. When the size of the electroacoustic transducer is reduced, the size of the diaphragm disposed inside the electroacoustic transducer is also reduced, and the sound quality is lowered as compared with the electroacoustic transducer having a large diaphragm.

On the other hand, in the earphone including the cord, the cord is connected to the housing and the sound source. Therefore, the movement of the user is easily restricted, and there is a possibility that the cord is broken due to a large force pulling the cord, and the earphone is detached from the ear of the user.

Therefore, in recent years, a wireless headset (hereinafter, simply referred to as "wireless headset") without a cord has been proposed. The wireless headset receives an audio signal from a sound source via a wireless communication circuit such as bluetooth (registered trademark). The wireless earphones include a wireless earphone in which left and right sound reproduction units are connected by a cable, and a so-called completely wireless earphone in which the left and right sound reproduction units are completely independent (the left and right sound reproduction units are not connected by a cable). Since the completely wireless earphone does not have a cable for connecting the left and right sound emitting units, the sound emitting unit has a higher degree of freedom in design than a wireless earphone in which the left and right sound emitting units are connected by a cable.

Here, electrical components such as a battery and a circuit board are disposed in the housing of the wireless headset. In the inner space of the housing, electrical components such as a battery and a circuit board are disposed in the rear space of the electroacoustic transducer.

However, if the electroacoustic transducer is disposed in the rear space in the vicinity of an electric element such as a battery or a circuit board, the acoustic characteristics of the rear space change, and the sound quality of the electroacoustic transducer (the sound quality of the sound wave output from the electroacoustic transducer) deteriorates. On the other hand, if the electroacoustic transducer and the electric elements such as the battery and the circuit board are separately arranged, the volume of the internal space of the housing increases, and the size of the housing increases. In this case, as described above, since all or a part of the case is disposed in the concha cavity of the user, if the case is enlarged, the comfort of wearing the headset by the user is reduced.

On the other hand, by disposing the electroacoustic transducer in the sound guide tube as in the earphone disclosed in patent document 1, a space can be formed in the inner space of the housing, and electric elements such as a battery and a circuit board can be disposed. However, as described above, since the size of the electroacoustic transducer arranged in the sound guide tube is controlled to a small extent, the sound quality of the electroacoustic transducer is degraded.

The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a wireless earphone which can reduce the size of a casing and suppress the influence of the arrangement of electric elements such as a battery and a circuit board on the sound quality of an electroacoustic transducer.

Means for solving the problems

The wireless headset of the present invention is characterized by comprising: an electroacoustic transducer that outputs a sound wave corresponding to an audio signal from a sound source; a receiving circuit that receives an audio signal from a sound source via a wireless communication circuit; a circuit board on which a receiving circuit is mounted; and a housing that houses the circuit board and the electroacoustic transducer. The housing includes: a 1 st housing accommodating an electroacoustic transducer; and a 2 nd housing accommodating the circuit board.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to reduce the size of the casing and suppress the influence of the arrangement of the electric elements such as the battery and the circuit board on the sound quality of the electroacoustic transducer.

Drawings

Fig. 1 is a perspective view showing an embodiment of a wireless headset of the present invention.

Fig. 2 is a front view of a left playback unit provided in the wireless headset of fig. 1.

Fig. 3 is a sectional view of the left playback unit of fig. 2, taken along the line a-a.

Fig. 4 is a functional block diagram of the wireless headset of fig. 1.

Detailed Description

● Wireless earphone ●

Embodiments of a wireless headset according to the present invention will be described below with reference to the accompanying drawings.

Fig. 1 is a perspective view showing an embodiment of a wireless headset of the present invention.

The wireless headset 1 is worn on the ear of a user of the wireless headset 1, and outputs a sound wave corresponding to an audio signal from a sound source S (see fig. 4) such as a portable music player. The wireless headset 1 receives an audio signal from a sound source S via a wireless communication circuit such as bluetooth (registered trademark).

The wireless headset 1 has a left playback unit 10 and a right playback unit 20. The wireless headset 1 is a so-called complete wireless headset, and the left sound emitting unit 10 and the right sound emitting unit 20 are completely independent from each other without being connected by a cable or the like.

In the following description, the front direction of the wireless headset 1 refers to a direction toward the head of the user (a direction on the left side of the paper surface in fig. 3) in a state where the wireless headset 1 is worn on the head of the user (hereinafter, simply referred to as a "worn state"). The rear direction of the wireless headset 1 is a direction (direction on the right side of the paper surface in fig. 3) opposite to the direction of the head of the user in the worn state.

● Wireless earphone configuration ●

Fig. 2 is a front view of the left playback unit 10.

Fig. 3 is a sectional view of the left playback unit 10 taken along the line a-a in fig. 2.

First, the left playback unit 10 will be explained.

The left playback unit 10 is worn on the left ear of the user, and outputs a sound wave corresponding to an audio signal from a sound source S (see fig. 4). The left playback unit 10 includes: the left shell 11, the left sound guide tube 12, the left earphone 13, the left electroacoustic transducer 14, the left circuit board 15 and the left battery 16.

The left housing 11 accommodates: a left electroacoustic transducer 14, a left circuit board 15, a left battery 16. The left housing 11 is made of synthetic resin such as plastic. The left housing 11 includes: a 1 st housing 111, a 2 nd housing 112, and a 3 rd housing 113.

The 1 st enclosure 111 and the 2 nd enclosure 112 collectively house the left electro-acoustic transducer 14. The 1 st housing 111 has a substantially bowl shape opened at the rear. The 1 st housing 111 has a communication hole 111h at the bottom. As for the communication hole 111h, see the following.

The 2 nd housing 112 and the 1 st housing 111 together house the left electro-acoustic transducer 14. In addition, the 2 nd housing 112 and the 3 rd housing 113 accommodate the left circuit board 15 and the left battery 16 together. The 2 nd housing 112 has a substantially drum shape that opens in the front and rear directions. The 2 nd housing 112 includes a constricted portion 1121 and a partition portion 1122.

The contracting portion 1121 is disposed on the antitragus of the left ear of the user in the worn state, and fixes the left housing 11 to the left ear.

The partition 1122 is disposed inside the constricted portion 1121, and partitions (partitions) the space inside the 2 nd housing 112 in the front-rear direction. The partition 1122 has a communication hole 1122 h. The communication hole 1122h is disposed at the center of the partition 1122, and communicates the spaces inside the 2 nd housing 112 partitioned in the front-rear direction by the partition 1122.

The 3 rd housing 113 and the 2 nd housing 112 collectively house the left circuit board 15 and the left battery 16. The 3 rd housing 113 has a substantially disc shape.

The 1 st housing 111 is engaged with the opening on the front side of the 2 nd housing 112, covering the opening. The 3 rd housing 113 is engaged with the opening on the rear side of the 2 nd housing 112, covering the opening. As a result, the 1 st case 111 and the 2 nd case 112 together constitute the 1 st case 11A of the present invention in front of the partition 1122. On the other hand, the 3 rd case 113 and the 2 nd case 112 constitute the 2 nd case 11B of the present invention together with a portion on the rear side of the partition 1122. That is, the left housing 11 is bounded by the partition 1122 (the constricted portion 1121), and includes a 1 st housing 11A and a 2 nd housing 11B disposed behind the 1 st housing 11A. In other words, the 1 st case 11A is joined to the 2 nd case 11B at the partition 1122 (the constricted portion 1121).

The 1 st case 11A includes a 1 st shell 111 and a 2 nd shell 112. The 2 nd case 11B includes a 2 nd shell 112 and a 3 rd shell 113. That is, the 2 nd housing 112 is a common component between the 1 st case 11A and the 2 nd case 11B.

The 1 st housing 11A accommodates the left electro-acoustic transducer 14. The 1 st case 11A is a portion on the front side of the partition 1122 of the left case 11. The 1 st case 11A includes a 1 st space R1 therein. The 1 st space R1 is a space inside the 1 st case 11A formed (partitioned) by the 1 st shell 111 and the 2 nd shell 112.

The 2 nd housing 11B accommodates a left circuit board 15 and a left battery 16. The 2 nd housing 11B is a portion behind the partition 1122 of the left housing 11. The 2 nd case 11B includes a 2 nd space R2 therein. The 2 nd space R2 is a space inside the 2 nd case 11B formed (partitioned) by the 2 nd shell 112 and the 3 rd shell 113. The 2 nd space R2 communicates with the 1 st space R1 via the communication hole 1122 h.

When the wireless headset 1 is used, the left sound guide tube 12 guides the sound waves from the left electro-acoustic transducer 14 to the external auditory canal of the user. The left sound guide tube 12 is substantially cylindrical. That is, the left sound guide tube 12 has a space (hereinafter referred to as "internal space") 121R inside thereof through which the sound waves from the left electroacoustic transducer 14 pass. The left sound guide tube 12 is disposed in front of the 1 st housing 111, and is configured integrally with the 1 st housing 111 so as to protrude downward from the bottom of the 1 st housing 111 in the front direction (downward direction of the paper in fig. 3). In other words, the 1 st housing 111 includes the left sound guide tube 12 protruding from the bottom. The internal space 121R communicates with the 1 st space R1.

Further, as long as the internal space communicates with the 1 st space, the left sound guide tube may be configured separately from the 1 st housing. That is, for example, the left sound guide tube may be engaged with the bottom of the 1 st housing, protruding from the bottom of the 1 st housing. That is, the 1 st housing may also be configured to: is joined with the left sound guide tube.

The left earpiece 13 is in close contact with the inner wall of the external auditory canal of the user in the wearing state. The left earpiece 13 is attached to the outer circumferential surface of the left sound guide tube 12. The left earpiece 13 is a resilient material such as silicone. The left earpiece 13 is substantially double-tube shaped with its front end folded back in a U-shaped cross section.

The left electro-acoustic transducer 14 outputs an acoustic wave corresponding to an audio signal from the sound source S. The left electro-acoustic transducer 14 is, for example, a moving coil electro-acoustic transducer. The left electroacoustic transducer 14 is disposed in the 1 st space R1 of the 1 st case 11A (accommodated in the 1 st case 11A) in the left case 11. As shown in fig. 3, the 1 st space R1 is divided into a front space R11 and a rear space R12 by the left electro-acoustic transducer 14.

The front space R11 is a space forward of the left electro-acoustic transducer 14 in the 1 st space R1. The rear space R12 is a space behind the left electroacoustic transducer 14 in the 1 st space R1, and is located on the 2 nd space R2 side. The front space R11 and the rear space R12 are spaces having sound volume.

The front space R11 communicates with the space outside the left housing 11 via an acoustic resistor (not shown) and the communication hole 111 h. That is, the communication hole 111h is a hole that communicates the front space R11 and the space outside the left housing 11. Of the sound waves from the left electroacoustic transducer 14, sound waves of a low audio frequency band are emitted from the communication hole 111h to a space outside the left housing 11. Therefore, the bass frequency band of the sound wave emitted by the left playback unit 10 is suppressed. The communication hole 111h suppresses an increase in pressure in the front space R11, which occurs when the left sound emitting unit 10 is attached to the left ear of the user (when the left sound emitting unit is attached to the pinna of the user), and prevents damage to the left electroacoustic transducer 14 (for example, damage to a diaphragm (not shown) provided in the left electroacoustic transducer 14).

The left circuit board 15 is a substrate on which an electronic circuit described later is mounted (mounted). The left circuit board 15 is disposed in the 2 nd space R2 of the 2 nd case 11B (accommodated in the 2 nd case 11B).

Fig. 4 is a functional block diagram of the wireless headset 1.

The left circuit board 15 is provided with a receiving circuit 151, a signal processing circuit 152, and a transmitting circuit 153. The receiving circuit 151, the signal processing circuit 152, and the transmitting circuit 153 are examples of the electronic circuit. That is, the left playback unit 10 includes: a receiving circuit 151, a signal processing circuit 152, and a transmitting circuit 153. The left circuit board 15 is, for example, a PCB (printed circuit board).

The receiving circuit 151 receives an audio signal from the sound source S via a wireless communication circuit. The audio signal received by the receiving circuit 151 is a digital signal. The receiving circuit 151 transmits the received audio signal to the signal processing circuit 152 and the transmitting circuit 153. The signal processing circuit 152 processes the audio signal received by the receiving circuit 151 and transmits the processed signal to the left electro-acoustic transducer 14. The signal processing circuit 152 is, for example, a digital-to-analog conversion circuit. That is, the signal processed by the signal processing circuit 152 (hereinafter, referred to as "processed signal") is, for example, an analog signal obtained by performing digital-to-analog conversion on a digital signal. The transmitting circuit 153 transmits the audio signal from the receiving circuit 151 to a receiving circuit 251 of the right playback unit 20, which will be described later. The receiving circuit 151, the signal processing circuit 152, and the transmitting circuit 153 are mounted on the left circuit board 15.

The left battery 16 supplies electric power for driving the electronic circuit mounted on the left circuit board 15 to the electronic circuit. The left battery 16 is, for example, a small button battery. The left battery 16 supplies electric power to the receiving circuit 151, the signal processing circuit 152, and the transmitting circuit 153 via the left circuit board 15.

Returning to fig. 3.

The left battery 16 and the left circuit board 15 are disposed together in the 2 nd space R2 of the 2 nd case 11B.

Here, the left electroacoustic transducer 14 is connected to the left circuit board 15 via a signal line inserted through the communication hole 1122 h. The communication hole 1122h through which the signal line is inserted is filled with, for example, an adhesive and sealed. Therefore, the 1 st space R1 in which the left electro-acoustic transducer 14 is disposed is separated from the 2 nd space R2 in which the left circuit board 15 and the left battery 16 are disposed. As described above, the 1 st space R1 is separated from the 2 nd space R2, whereby the acoustic characteristics of the rear space R12 are not affected by the left circuit board 15 or the left battery 16, thereby remaining stable. That is, the sound wave emitted from the left electro-acoustic transducer 14 to the 1 st space R1 is not affected by the left circuit board 15 and the left battery 16. As a result, the sound quality of the left electro-acoustic transducer 14 can be kept stable.

When the wireless headset 1 is used, the left sound reproduction unit 10 configured as described above is worn on the left ear of the user. At this time, the 1 st housing 11A is disposed in the cavum concha of the left ear of the user, a part of the partition 1122 (the constricted portion 1121) is supported (disposed) on the tragus and antitragus of the left ear of the user, and the 2 nd housing 11B is disposed outside the cavum concha. That is, in the worn state, the 2 nd housing 11B is exposed to the outside of the concha cavity. That is, in the wearing state, the left electroacoustic transducer 14 is located inside the concha cavity, and the electrical components such as the left circuit board 15 and the left battery 16 are located outside the concha cavity.

The right playback unit 20 is worn on the right ear of the user, and outputs a sound wave corresponding to an audio signal from a sound source S (see fig. 4). The right playback unit 20 has the same configuration as the left playback unit 10 except that it does not include a transmission circuit. That is, the right playback unit 20 includes: right casing 21, right sound guide tube (not shown), right earphone 23, right electroacoustic transducer 24, right circuit board 25, right battery 26. The right housing 21 includes: a 1 st case 21A and a 2 nd case 21B. A receiving circuit 251 and a signal processing circuit 252 are mounted on the right circuit board 25.

● action of wireless earphone

Next, the operation of the wireless headset 1 will be described with reference to fig. 4.

A digital signal (audio signal) from the sound source S is transmitted to the receiving circuit 151 of the left playback unit 10 via a wireless communication circuit. The receiving circuit 151 transfers the received digital signal (audio signal) to the signal processing circuit 152 and the transmitting circuit 153.

The signal processing circuit 152 converts the digital signal (audio signal) input from the receiving circuit 151 into an analog signal (audio signal) and transmits the analog signal to the left electro-acoustic transducer 14. The left electro-acoustic transducer 14 outputs an acoustic wave based on the analog signal (audio signal) input from the signal processing circuit 152.

On the other hand, the transmitting circuit 153 transmits the digital signal (audio signal) transmitted from the receiving circuit 151 to the receiving circuit 251 of the right playback unit 20. The receiving circuit 251 transmits the digital signal (audio signal) transmitted from the transmitting circuit 153 of the left playback unit 10 to the signal processing circuit 252. The signal processing circuit 252 converts the digital signal (audio signal) input from the receiving circuit 251 into an analog signal (audio signal) and transmits the analog signal to the right electroacoustic transducer 24. The right electro-acoustic transducer 24 outputs an acoustic wave based on the analog signal (audio signal) input from the signal processing circuit 252.

● summary

According to the embodiment described above, the left electroacoustic transducer 14 is accommodated in the 1 st space R1 of the 1 st housing 11A, and the electric components such as the left circuit board 15, the left battery 16, and the like, on which the receiving circuit 151 is mounted, are accommodated in the 2 nd space R2 of the 2 nd housing 11B. The 1 st space R1 is separated from the 2 nd space R2 by a partition 1122. As a result, the left electroacoustic transducer 14 is spatially spaced apart from the electrical components such as the left circuit board 15 and the left battery 16.

In the wireless headset of the present invention, since the left electroacoustic transducer 14 is spatially disposed at a distance (separated) from the electrical components such as the left circuit board 15 and the left battery 16, the physical distance between the left electroacoustic transducer 14 and the electrical components can be reduced. That is, compared with the conventional earphone in which the electroacoustic transducer and the electric elements such as the circuit board and the battery are disposed in the same space, the wireless earphone of the present invention does not affect the acoustic characteristics of the rear space, and the physical distance between the electroacoustic transducer and the electric elements is shortened, thereby achieving miniaturization.

When the 1 st housing 11A is disposed in the concha cavity, the 2 nd housing 11B is disposed (exposed) outside the concha cavity. That is, the electrical components such as the left circuit board 15 and the left battery 16 are disposed outside the concha cavity, and the left electroacoustic transducer 14 is disposed in the concha cavity. As a result, the wireless headset of the present invention can reduce the volume of the housing exposed to the outside of the concha cavity without reducing the wearing comfort of the user, as compared with the conventional headset. In addition, the size of the electroacoustic transducer of the present invention can be selected to be larger than the size of the electroacoustic transducer arranged in the sound guide tube and the electroacoustic transducer arranged in the same space as the electric element. As a result, according to the wireless headset of the present invention, the degree of freedom in selection of the electroacoustic transducer can be increased, thereby improving the sound quality.

As described above, the wireless headset according to the present invention is a completely wireless headset in which the circuit board and the battery are accommodated in the case, but can be miniaturized and can suppress the influence on the sound quality.

The above-described embodiment is configured such that: the analog signals are converted to sound waves by the left and right electro-acoustic transducers. In addition, the following configuration may be adopted: the digital signals are converted into sound waves by the left and right electro-acoustic transducers. In this case, the signal processing circuit processes the audio signal received by the receiving circuit in a digital signal state (sorting, extracting, synthesizing, etc. of necessary signals), and transmits the processed signal to the left and right electroacoustic transducers.

The communication holes communicating the 1 st space and the 2 nd space may be filled with no adhesive. In this case, the 2 nd space and the 1 st space function together as a rear space of the electroacoustic transducer (left and right electroacoustic transducers).

The 2 nd housing may have a communication hole for communicating the rear space with the external space of the right and left housings (1 st housing). In this case, the rear space can be acoustically regarded as a part of the space outside the left and right housings. Therefore, the rigidity of the air in the rear space is lowered, and the vibration of the diaphragm provided in the left and right electroacoustic transducers is less likely to be braked by the air in the rear space. As a result, the 2 nd housing can reduce the volume of the rear space more than the left and right housings without the communication hole, and the left and right housings can be downsized.

Description of the reference numerals

1: wireless earphone

10: left playback unit

11: left shell

11A: no. 1 casing

111: no. 1 outer case

112: no. 2 outer case

113: no. 3 outer case

1122 h: communicating hole

11B: no. 2 casing

12: left sound guide tube

121R: inner space

13: left earphone

14: left electroacoustic transducer

15: left circuit board

151: receiving circuit

16: left battery

R1: 1 st space

R2: 2 nd space

S: a sound source.