Sound presentation device

A sound presentation device including: a casing; an electroacoustic transducer that is installed in such a way that a space inside the casing is divided into a first empty chamber and second empty chamber that are acoustically isolated, and that receives an electrical signal and vibrates; and a vibration plate that makes contact with a body surface of a human body when the sound presentation device is mounted on the body surface, and causes vibration of the electroacoustic transducer to be propagated to the human body via the first empty chamber, the second empty chamber suppressing sound waves produced by the vibration of the electroacoustic transducer from being emitted to outside of the sound presentation device via the second empty chamber.

BACKGROUND

1. Technical Field

The present disclosure relates to a sound presentation device.

2. Description of the Related Art

Bone conduction headphones are used as a way of being able to hear sound without covering the ears (for example, Japanese Unexamined Patent Application Publication No. 2011-130334).

SUMMARY

In one general aspect, the techniques disclosed here feature a sound presentation device including: a casing; an electroacoustic transducer that is installed in such a way that a space inside the casing is divided into a first empty chamber and second empty chamber that are acoustically isolated, and that receives an electrical signal and vibrates; and a vibration plate that makes contact with a body surface of a human body when the sound presentation device is mounted on the body surface, and causes vibration of the electroacoustic transducer to be propagated to the human body via the first empty chamber, the second empty chamber suppressing sound waves produced by the vibration of the electroacoustic transducer from being emitted to outside of the sound presentation device via the second empty chamber.

According to the sound presentation device of the present disclosure, it is possible to ensure the volume required to hear sound while also reducing user discomfort caused by a vibration element being pressed firmly against the head.

DETAILED DESCRIPTION

Findings Forming the Basis of the Present Disclosure

In the bone conduction headphone device described in Japanese Unexamined Patent Application Publication No. 2011-130334, a bone conduction speaker is provided at an end section of a headband, and the bone conduction speaker presses against the side surface of the head in front of an ear of the user. The bone conduction speaker is further provided with a main vibration output unit that transmits sound to the user by bone conduction and an auxiliary vibration output unit that transmits sound to the user by cartilage conduction.

In the bone conduction headphones described in Japanese Unexamined Patent Application Publication No. 2011-130334, the transmission of vibration by bone conduction is achieved by the bone conduction speaker pressing against the side surface of the head due to the restoring force of the headband mounted on the head of the user. Therefore, pressure is constantly applied to the skin of the parts against which the bone conduction speaker presses, which results in discomfort for the user.

Furthermore, in the bone conduction headphones described in Japanese Unexamined Patent Application Publication No. 2011-130334, a driver mounted in the bone conduction speaker vibrates the side surface of the head of the user either directly or via a solid body, and therefore the position of the driver is in principle restricted to being on the axis of the transmission direction of the vibration, which results an increase in the thickness of the part that presses against the head of the user.

In other words, in the method described in Japanese Unexamined Patent Application Publication No. 2011-130334, it is necessary for a vibration element to be firmly pressed against the head in order to obtain a sufficient volume, and further examination has been necessary to make it possible for sound to be heard under conditions that are comfortable for the user.

The present disclosure provides a sound presentation device with which it is possible to hear sound at a sufficient volume without the ears being covered while also reducing discomfort.

A sound presentation device of the present disclosure is a sound presentation device including: a casing; an electroacoustic transducer that is installed in such a way that a space inside the casing is divided into a first empty chamber and second empty chamber that are acoustically isolated, and that receives an electrical signal and vibrates; and a vibration plate that makes contact with a body surface of a human body when the sound presentation device is mounted on the body surface, and causes vibration of the electroacoustic transducer to be propagated to the human body via the first empty chamber, the second empty chamber suppressing sound waves produced by the vibration of the electroacoustic transducer from being emitted to outside of the sound presentation device via the second empty chamber.

Furthermore, for example, the vibration plate may include at least a first vibration plate and a second vibration plate, the first empty chamber may include at least a first region and a second region, the casing may include at least a first casing that forms the first region and a second casing that forms the second region, the first vibration plate may be arranged in the first casing, and the second vibration plate may be arranged in the second casing.

Furthermore, for example, the first casing may include a hole, the second casing may include a cylindrical body that is a hollow cylinder, and the first region and the second region may be linked due to the cylindrical body being inserted into the hole.

Furthermore, for example, the second empty chamber may be hermetically sealed by the casing to thereby suppress the sound waves from being emitted to outside of the sound presentation device.

Furthermore, for example, a sound absorbing material may be arranged in part of the second empty chamber to thereby suppress the sound waves from being emitted to outside of the sound presentation device.

Furthermore, for example, a spacer that is disposed inside the casing and makes contact with both the vibration plate and a casing inner wall may be provided.

Furthermore, for example, the spacer may divide the first empty chamber into a plurality of regions, and the plurality of regions may be linked due to a hole being provided in part of the spacer.

Furthermore, for example, the flexural rigidity of a portion of the casing that covers the first empty chamber may be greater than the flexural rigidity of the vibration plate, and the vibration plate may have a bent shape.

Furthermore, for example, the casing that forms a wall surface of the second empty chamber may suppress the sound waves produced by the vibration of the electroacoustic transducer from being emitted to outside of the sound presentation device.

A sound presentation device according to an aspect of the present disclosure will be described in detail with reference to the drawings.

It should be noted that the embodiments described hereinafter all represent a specific example of the present disclosure. The numerical values, the shapes, the materials, the constituent elements, and the arrangement positions of the constituent elements and the like given in the following embodiments are examples and are not intended to restrict the present disclosure. Furthermore, from among the constituent elements in the following embodiments, constituent elements that are not described in the independent claim indicating the most significant concepts are described as optional constituent elements.

In other words, embodiments that are examples for realizing a sound presentation device according to an aspect of the present disclosure are described hereinafter; however, each embodiment is merely an example and is not restricted to the following description. Furthermore, all of the content described in the embodiments is able to be combined.

Hereinafter, a sound presentation device in Embodiment 1 will be described with reference to the drawings.

FIGS. 1A and 1Bare drawings depicting an example of a state in which a sound presentation device100in Embodiment 1 is worn. The sound presentation device100is mounted on the surface of a body (also referred to as a body surface) and used. In this regard, an example will be described in which the sound presentation device100is mounted on a head1of a person as the body surface and used, for example.

FIG. 1Ais a drawing in which the head1of the person on which the sound presentation device100is mounted is viewed from the side, andFIG. 1Bis a drawing in which the head1of the person on which the sound presentation device100is mounted is viewed from behind.

The sound presentation device100in the present embodiment is provided with an arm110and a sound transmission section111. In Embodiment 1, the sound transmission section111of the sound presentation device100is disposed at an end section of the arm110and is arranged in such a way as to make contact in front of an ear. The arm110has an approximate U-shape that follows the back of the head, and holds the sound presentation device100in a prescribed position on the head1of the user. The rigidity of the arm110is selected within a range with which the sound transmission section111does not separate from the skin and the user is not aware of the force that is applied to the skin. It should be noted that the arm110is not an essential configuration.

FIGS. 2A to 2Care drawings depicting an example of the configuration of the sound transmission section111in Embodiment 1.

FIG. 2Ais a side view in which the sound transmission section111of the sound presentation device100is seen from the head1side when mounted.FIG. 2Bis an upper side view of the sound transmission section111depicted inFIG. 2A, andFIG. 2Cis an upper side view of the sound transmission section111depicted inFIG. 2Awhen casings103and104are bent toward the body.

As depicted inFIGS. 2A to 2C, the sound transmission section111is integrally connected to the arm110and is provided with: a casing102having an exciter101provided therein; the casing103connected to the casing102by a hinge structure; and the casing104connected to the casing103by the hinge structure.

FIGS. 3A and 3Bare cross-sectional views of the sound transmission section111in Embodiment 1. Specifically,FIG. 3Ais a IIIA-IIIA cross-sectional view of the sound transmission section111depicted inFIG. 2A.FIG. 3Bis a IIIB-IIIB cross-sectional view of the sound transmission section111depicted inFIG. 3A. More specifically,FIG. 3Bis a IIIB-IIIB cross-sectional view of the casing102in the sound transmission section111depicted inFIG. 3A.

FIG. 3Cis a IIIC-IIIC cross-sectional view of the casing102depicted inFIG. 3B.FIG. 3Dis a drawing depicting an example of the configuration of the casing103in the sound transmission section111depicted inFIG. 3A. Specifically,FIG. 3Ddepicts a cross section of the casing103, and this cross section is parallel with the IIIB-IIIB cross section depicted inFIG. 3A.

As depicted inFIG. 3A, the casing102includes the aforementioned exciter101, a front empty chamber105, a rear empty chamber106, and a vibration plate107a. It is preferable that the flexural rigidity in an arbitrary direction parallel with the surface of the vibration plate107athat makes contact with the body be a lower value than the flexural rigidity of, within the wall surface forming the casing102, the section that has the lowest flexural rigidity in the direction parallel with the inner wall.

The exciter101is installed in such a way that a space inside the casing102is divided into the front empty chamber105and the rear empty chamber106, which are acoustically isolated. The exciter101is also referred to as an electroacoustic transducer and receives an electrical signal and vibrates. An acoustic signal (or a sound wave) is produced by vibration of the exciter101. The exciter101is not particularly restricted as long as the exciter101converts an electrical signal into an acoustic signal.

The front empty chamber105is preferably a narrow space such that the sound transmission section111has a shape that follows the head1of the user, and preferably has a thickness with which the transmission of sound is not obstructed due to a resistance component of the inner wall; a thickness of 0.5 mm to 2 mm may be selected, for example. Furthermore, the volume of the front empty chamber105may be set to be small within the scope of the aforementioned preferable specification in order to increase the high-band reproduction limit frequency of the sound transmission section111.

The rear empty chamber106is provided in order to prevent sound waves that are produced on the opposite side to the front empty chamber105from among the sound waves produced by the vibration of the exciter101from leaking outside of the sound presentation device100and being radiated around the head, and is preferably linked with a space inside the arm110. Furthermore, the casing102that forms the wall surface of the rear empty chamber106is acoustically isolated from the outside of the sound presentation device100. For example, the section of the casing102that forms the wall surface of the rear empty chamber106may have a thickness of a degree with which vibration does not occur or it is considered that vibration does not occur due to changes in the pressure in the rear empty chamber106produced by the vibration of the exciter101.

Thus, sound waves produced by the vibration of the exciter101do not pass through the front empty chamber105(or through the rear empty chamber106) and are prevented from leaking outside of the sound presentation device100and being radiated around the head.

In other words, sound waves produced by the vibration of the exciter101solely cause a vibration plate107to vibrate via the front empty chamber105.

Thus, the vibration plate107causes the vibration of the exciter101to be propagated to the human body via the front empty chamber105.

The vibration of the vibration plate107is propagated to the human body from the location at which the vibration plate107makes contact with the human body. The vibration propagated to the human body transmits sound to the user by bone conduction.

Furthermore, it is also feasible for sound to be transmitted to the user by the vibration propagated to the human body being transmitted to the external auditory canal (earhole) and being radiated as sound to the space within the external auditory canal (earhole) and then being transmitted to the eardrum. The transmission of sound such as this is referred to as air conduction.

It is therefore feasible for the transmission of sound to the user based on vibration propagated to the human body to be transmission by only bone conduction or transmission by bone conduction and air conduction.

Furthermore, if the wall surface of the front empty chamber105of the casing102and the wall surface of the rear empty chamber106are formed in a uniform manner, vibration does not occur or it is considered that vibration does not occur due to changes in the pressure in the front empty chamber105produced by the vibration of the exciter101, also with regard to the section of the casing102that forms the wall surface of the front empty chamber105.

Furthermore, although it is desirable that the rear empty chamber106be hermetically sealed, the same action is obtained if a sound absorbing material, which is not depicted, is arranged in an open region when the rear empty chamber106is not hermetically sealed.

The vibration plate107ais installed in an opening in the front empty chamber105side of the casing102and is fixed at the peripheral edges of the opening. In order to make contact with the human body when mounted, it is desirable that the vibration plate107abe configured of a material having a rigidity with which it is possible for the vibration plate107ato be in close contact with the human body and for the entirety of the vibration surface to vibrate at the same phase. Specifically, it is desirable that the rigidity of the vibration plate107abe lower than the lowest value of a rigidity value range with which a gap is produced between the vibration plate107aand the human body, and be higher than the highest value of a rigidity value range with which displacement that occurs when the vibration surface vibrates has positive and negative values. For example, the vibration plate107amay be configured of a resin material such as ABS, a polyimide, polyetherimide, a paper material, a fibrous material, a metal material such as aluminum, or a laminated material or a composite material thereof. It should be noted that the vibration plate107is similarly installed also in the casing103and the casing104, and is depicted as the vibration plate107band the vibration plate107cinFIG. 3E.

As depicted inFIGS. 3B and 3C, holes109for connecting with cylindrical bodies108(a cylindrical body108aand a cylindrical body108b) described later on are included in the casing102.

As depicted inFIG. 3D, the cylindrical body108aand the cylindrical body108bare included in the casing103. As depicted inFIG. 2A, the casing102and the casing103engage at recessed and protruding sections thereof. At these engagement points, the cylindrical body108aof the casing103is inserted into the holes109of the casing102to thereby be flexibly connected. The cylindrical body108ais a hollow member that has an opening110a. The opening110aof the cylindrical body108ais connected to a space inside the casing103. The casing103and the casing104are also similarly flexibly connected by the cylindrical body108b, and spaces inside thereof are connected via a hollow section of the cylindrical body108b.

As depicted inFIG. 3E, the spaces inside each of the casing102, the casing103, and the casing104are linked by the holes109and the cylindrical bodies108aand108band the like.

The operation of the sound presentation device100in the present embodiment will be briefly described.

An external sound signal is received by a wireless communication unit of the sound presentation device100that is not depicted, is amplified by a voltage amplification unit that is not depicted, and is input to the exciter101. The exciter101vibrates according to the change in voltage of the external sound signal, the pressure in the space inside the casing102in which the exciter101is positioned changes, and sound waves are thereby produced.

At such time, because the front empty chamber105of the casing102and the space inside the casing103are linked via the hollow section of the cylindrical body108aconnected to the holes109, these spaces are substantially integrated and expand and contract according to the amount of vibration of the exciter101, and the vibration plates107aand107bare made to vibrate. The space inside the casing104is also similarly linked with the space inside the casing103via a cylindrical body108, and therefore the vibration plate107calso vibrates according to the amount of vibration of the exciter101.

The bone conduction headphone device described in Japanese Unexamined Patent Application Publication No. 2011-130334 is a configuration in which the main vibration output unit and the auxiliary vibration output unit directly vibrate the head, and therefore the vibration area is limited and it is necessary for the main vibration output unit to be firmly pressed against the head in order to transmit by bone conduction a volume that is sufficient to hear sound, which results in user discomfort.

In this regard, according to the sound presentation device100in Embodiment 1, the exciter101is a configuration that causes the vibration plate107to vibrate via the front empty chamber105, and therefore it is possible to obtain a large area for the vibration plate107and thereby reduce the pressing force required to obtain a volume that is subjectively the same. Therefore, compared with the bone conduction headphone device described in Japanese Unexamined Patent Application Publication No. 2011-130334, it becomes possible to reduce user discomfort caused by pressing against the head.

Furthermore, the exciter101is a configuration that drives the vibration plate107a, the vibration plate107b, and the vibration plate107cvia the front empty chamber105, and therefore it is not necessary for the exciter101to be arranged in a direction perpendicular to the center of the vibration plate107. Consequently, it is possible to design the shape of the vibration plate107and the shapes of the casings in accordance with requirements for the wearing feeling and external appearance without being limited by the position of the exciter101.

Furthermore, the vibration plate107a, the vibration plate107b, and the vibration plate107care integrated and vibrate according to the amount of vibration of the exciter101, and therefore vibrate as one vibration plate107. Thus, the vibration plate107of the sound presentation device100overall have a substantially concave shape (substantially bent shape) or a concave shape (bent shape) with respect to the body, and therefore can make contact with the skin along the convex shape of the head, and the risk of separation from the skin can be reduced even when the area is large.

Furthermore, the flexural rigidity of the vibration plate107is lower than the flexural rigidity of the casings102,103, and104. In other words, the flexural rigidity of the wall surfaces of the casings102,103, and104is higher than the flexural rigidity of the vibration plate107. Therefore, it is possible for the members that vibrate due to changes in the pressure in the spaces inside the front empty chamber105, the casing103, and the casing104to be limited to only the vibration plate107. Consequently, it is possible to suppress the leakage of sound to outside of the head caused by excessive vibration of the casings102, the casing103, and the casing104and suppress energy consumption that does not contribute to hearing sound.

As indicated above, according to the sound presentation device100in the present embodiment, the body surface is vibrated by a vibration plate having a substantially bent shape (or a bent shape) that follows the shape of the head, and therefore it is possible to increase the vibration area compared with conventional bone conduction headphones. Therefore, it is possible to reduce the pressure on the body surface when the same vibration force is transmitted to the middle ear compared with conventional bone conduction headphones, and it is possible to reduce user discomfort caused by pressing by a vibration element while also ensuring a volume.

Furthermore, rather than the body surface or the vibration plate107abeing directly vibrated by the exciter101, the vibration plate107ais vibrated via the front empty chamber105and the body surface is vibrated via the vibration plate107a. By causing the vibration plate107to vibrate once via the front empty chamber105in this way, the vibration plate107having a large area can be made to vibrate in a stable manner by a small force.

Furthermore, in the sound presentation device100in the present embodiment, the space inside the casing102is separated into two empty chambers by the exciter101, namely the front empty chamber105and the rear empty chamber106. The front empty chamber105causes the vibration of the exciter101to be propagated to the vibration plate107, and the rear empty chamber106suppresses sound waves produced at the opposite side to the front empty chamber105by the vibration of the exciter101from being radiated to outside the sound presentation device100.

Furthermore, in Embodiment 1, the sound transmission section111is arranged so as to make contact in front of the ear as depicted inFIGS. 1A and 1B; however, the position of the sound transmission section111is not restricted thereto. For example, the sound transmission section111may be arranged so as to make contact with a lower section behind the ear as indicated by a sound presentation device100A depicted inFIGS. 4A and 4B. In this regard,FIGS. 4A and 4Bare drawings depicting an example of a state in which the sound presentation device100A in a modified example of Embodiment 1 is worn.FIG. 4Ais a drawing in which the head1of the person on which the sound presentation device100A is mounted is viewed from the side, andFIG. 4Bis a drawing in which the head1of the person on which the sound presentation device100A is mounted is viewed from behind. According to the present configuration, the sound transmission section111is not exposed to the face section, and therefore any effect on appearance such as the clothing and hairstyle of the user can be minimized.

It should be noted that, in the present configuration, it is desirable that the sound presentation device100A be further provided with a holding unit112for holding the sound transmission section111at a lower section behind the ear. The holding unit112may have a hook shape that hooks onto the ear as depicted inFIGS. 4A and 4B, and may have a necklace shape that hangs around the neck or a headband shape that encloses the head from above.

Furthermore, the vibration plates107ato107care configurations with which the all of the surfaces thereof make contact with the skin; however, the skin-side surface shape is not restricted thereto. For example, in order to alleviate discomfort due to stuffiness caused by stuffy heat, sweat, or sebum, the surfaces of the vibration plates may be provided with recesses and protrusions or may be provided with one or more holes as long as the air inside the front empty chamber and outside air are not connected. In addition, fabric may be stretched across one or both surfaces of the vibration plates, and fabric having a water-absorbing or antibacterial function or the like may be used for the skin-side surface, and fabric having a water-repelling function or the like may be used for the front empty chamber-side surface, for example.

Furthermore, an element such as a sensor may be provided on the vibration plates107ato107cand the casings102to104as long as the function to transmit vibration to the human body is not impaired, and any of a contact sensor, a temperature sensor, a pulse sensor, or an acoustic sensor may be used, for example. Furthermore, some or all of the vibration plates107ato107cmay also be provided with a sensor-element constituent mechanism.

In the present embodiment, an example has been given in which three casings are connected such as with the casings102to104; however, it should be noted that the present disclosure is not restricted thereto. Four or more casings may be similarly connected, or only one or two casings may be used.

Furthermore, the arm110is not an essential configuration in the present embodiment. For example, a configuration that does not have the arm110is also feasible if members that are adhesive with respect to skin are adopted for some of the configurations (the vibration plate107or the peripheral edge sections of the vibration plate107of the casings102to104, for example) within the sound transmission section111.

Hereinafter, a sound presentation device in Embodiment 2 will be described with reference to the drawings. It should be noted that descriptions that are the same as those in Embodiment 1 are omitted in parts of the present embodiment. Furthermore, it is also possible to combine with the technology described in Embodiment 1.

The state in which the sound presentation device in Embodiment 2 is worn is the same as in Embodiment 1 and therefore a depiction thereof is omitted. The differences with Embodiment 1 are that the casings that form the sound transmission section are a single body rather than a plurality of connected bodies, and that the bent shape is fixed. Furthermore, the casings are provided with spacers therein in Embodiment 2.

FIGS. 5A and 5Bare drawings depicting an example of the configuration of a sound transmission section211of the sound presentation device in Embodiment 2.FIG. 5Ais a side view in which the sound transmission section211of the sound presentation device is seen from a head1when mounted.FIG. 5Bis a VB-VB cross-sectional view of the sound transmission section211depicted inFIG. 5A.

A casing202includes an exciter201, a front empty chamber, a rear empty chamber that is not depicted, a vibration plate207a, a vibration plate207b, a vibration plate207c, a spacer208a, and a spacer208b. As depicted inFIG. 5B, the casing202overall has a curved shape (or a bent shape) that follows the shape of the head1.

The spacer208aand the spacer208bare provided inside the casing202and are fixed to the inner wall of the casing202. Furthermore, a hole209aand a hole209bare arranged in the spacer208aand the spacer208b, respectively.

The spacer208aand the spacer208bdivide the front empty chamber of the casing202into a front empty chamber205a, a front empty chamber205b, and a front empty chamber205c.

The hole209alinks the front empty chamber205aand the front empty chamber205b, and the hole209blinks the front empty chamber205band the front empty chamber205c. The vibration plates207ato207care installed in openings in the front empty chamber205side of the casing202and are fixed at the peripheral edges of the openings. Furthermore, the vibration plates207ato207care each supported by the spacer208aor the spacer208b.

The sections between the vibration plates207ato207cand the casing202, spacer208a, and spacer208bare sealed without any gaps. It should be noted that the vibration plates207ato207cmay be formed as a single body. In other words, a vibration plate207that is a single plate may be used and a portion of the vibration plate207may be arranged so as to make contact with the casing202, the spacer208a, and the spacer208b.

It is desirable that the rigidity of the spacers208aand208bbe lower nearer the contact surfaces with the vibration plates207ato207cand higher nearer the surfaces on the opposite side to the contact surfaces. The material of the spacers208aand208bmay be a polyurethane or the like near the contact surfaces with the vibration plates207ato207c, and may be the same material as the casing202in sections other than those near the contact surfaces, for example.

In this way, the same effect as that of Embodiment 1 is also obtained in Embodiment 2 for elements that are common to Embodiment 1. In addition, according to the sound presentation device in Embodiment 2, the spacers208aand208bdeform following the vibration of the vibration plates207ato207c, and therefore the vibration plates207ato207cvibrate in the same way as a single vibration plate without the movement being hindered by the spacers208aand208b, and the vibration area can be further increased as a result.

Furthermore, the spacers208aand208bdo not deform in sections other than those near the contact surfaces with the vibration plates207ato207c, and therefore it is possible to avoid the vibration plates207ato207cmaking contact with the inner wall of the casing202and to avoid the volume of the front empty chamber205changing due to the contact condition with a human body and the frequency characteristics of heard sound changing.

The front empty chamber205of the casing202is divided into three regions (the front empty chamber205a, the front empty chamber205b, and the front empty chamber205c) in the present embodiment; however, it should be noted that the present disclosure is not restricted thereto. The front empty chamber205may be divided into four or more regions, or divided into one or two regions. Furthermore, an arm110is not an essential configuration in the present embodiment. For example, the arm is not necessary if members that are adhesive with respect to skin are adopted for some of the configurations (the vibration plate207, for example) within the sound transmission section211.

Heretofore, a description of a sound presentation device according to one or more aspects of the present disclosure has been given based on the embodiments; however, the present disclosure is not restricted to these embodiments. Modes in which various modifications conceived by a person skilled in the art have been implemented in the present embodiments, and modes constructed by combining the constituent elements in different embodiments may also be included within the scope of one or more aspects of the present disclosure provided they do not depart from the purpose of the present disclosure.

It is possible for the sound presentation device according to the present disclosure to be provided as a wearable sound presentation device that achieves both comfort when worn and a volume that can be heard, and may be used in headphones, a wearable information terminal, a navigation device, a hearing aid, and a headset or the like.