Unit, electronic device, and method of manufacturing electronic device

According to one of aspects, provided is an electronic device including a panel 10, a piezoelectric element 30 attached to the panel 10, and a substrate 25 attached to a main surface of the piezoelectric element 30. The panel 10 is configured to be deformed due to deformation of the piezoelectric element 30, and sound is transmitted to an object that is in contact with the deformed panel 10. The substrate 25 includes a base 25a made of resin, and signal lines 25b and 25c laminated with the base 25a and connected to the main surface of the piezoelectric element 30. The substantially the entire main surface of the piezoelectric element 30 is covered by the base 25a.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to and the benefit of Japanese Patent Application No. 2013-114009 filed on May 30, 2013, Japanese Patent Application No. 2014-058024 filed on Mar. 20, 2014, and Japanese Patent Application No. 2014-058025 filed on Mar. 20, 2014. The entire contents of these documents are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an electronic device that vibrates a member (e.g., a panel) to which a piezoelectric element is attached, by applying a predetermined electric signal (i.e., a sound signal) to the piezoelectric element and that conveys the vibration of the member to a human body to thereby transmit vibration sound to a user through a part of the human body.

BACKGROUND

Patent Literature 1 describes an electronic device, such as a mobile phone, that transmits air conduction sound and bone conduction sound to a user. Patent Literature 1 also describes that the air conduction sound is sound perceived by an auditory nerve of a user as a result of an eardrum being vibrated by an air vibration that is created by a vibration of an object and that travels through an external auditory canal down to the eardrum. Patent Literature 1 also describes that the vibration sound is sound perceived by an auditory nerve of a user through a part of the body (for example. Cartilaginous portion) of the user which contacts with the vibrating object.

In the mobile phone described in Patent Literature 1, a rectangular plate-shaped vibration body configured by piezoelectric bimorph and a flexible material is attached to an outer surface of a housing by way of an elastic member. Patent Literature 1 also describes that, upon application of a voltage to the piezoelectric bimorph of the vibration body, the piezoelectric material is expanded and contracted in a longitudinal direction, thereby causing the vibration body to undergo flexture vibration. As a result, when the user places the vibration body in contact with an auricle, air conduction sound and vibration sound are transmitted to the user.

Patent Literature 2 describes an electronic device, such as a mobile phone terminal, that vibrates a panel due to deformation of a piezoelectric element attached to the panel, to thereby transmit human-body vibration sound to an object that is in contact with the panel.

CITATION LIST

Patent Literatures

SUMMARY

Technical Problem

The electronic devices described in Patent Literatures 1 and 2 are not designed to address the possibility that the piezoelectric element included in the vibration body will be deformed excessively and that external force will be applied to the piezoelectric element.

The present disclosure is to provide a unit, an electronic device, and a method of manufacturing the electronic device, all of which are capable of preventing excessive deformation of the piezoelectric element and preventing damage to the piezoelectric element caused by external force.

Solution to Problem

One aspect of the present disclosure resides in a unit, including: a panel; a piezoelectric element attached to the panel; and a substrate attached to a main surface of the piezoelectric element, wherein the panel is configured to be vibrated by the piezoelectric element, and sound is transmitted by the panel vibrating a part of a human body that is in contact with the deformed panel, the substrate includes a base made of resin and at least one signal line laminated with the base and connected to the main surface of the piezoelectric element, and substantially the entire main surface of the piezoelectric element is covered by the base.

Another aspect of the present disclosure resides in an electronic device, including at least the unit.

Yet another aspect of the present disclosure resides in an electronic device, including: a housing; a panel attached to the housing; a piezoelectric element attached to the panel, wherein the panel is configured to be deformed due to deformation of the piezoelectric element, and human-body vibration sound is transmitted to an object that is in contact with the deformed panel; and a protective member attached to a surface of the piezoelectric element that opposes to another surface of the piezoelectric element attached to the panel, wherein a surface of the protective member that opposes to another surface of the protective member attached to the piezoelectric element has a convex curved shape.

In one of preferred embodiments, the protective member covers both the surface of the piezoelectric element that is attached with the protective member and side surfaces extending from the surface of the piezoelectric element that is attached with the protective member.

Yet another aspect of the present disclosure resides in an electronic device, including: a housing; a piezoelectric element; a panel attached to the housing; an intermediate member disposed between the panel and the piezoelectric element, wherein the panel is configured to be deformed due to deformation of the piezoelectric element, and human-body vibration sound is transmitted to an object that is in contact with the deformed panel, and the piezoelectric element is attached to the intermediate member; and a protective member attached to a surface of the piezoelectric element that opposes to another surface of the piezoelectric element attached to the intermediate member, wherein a surface of the protective member that opposes to another surface of the protective member attached to the piezoelectric element has a convex curved shape.

In one of preferred embodiments, the protective member covers both the surface of the piezoelectric element that is attached with the protective member and side surfaces extending from the surface of the piezoelectric element that is attached with the protective member.

In one of preferred embodiments, an area of a surface of the intermediate member that is attached with the piezoelectric element is larger than an area of the other surface of the piezoelectric element that is attached to the intermediate member.

In one of preferred embodiments, the intermediate member is attached to the panel and the piezoelectric element by a joining member, and a surface of the intermediate member that is attached with the panel or the piezoelectric element is provided with a groove.

Yet another aspect of the present disclosure resides in an electronic device, including: a housing; a panel attached to the housing; a piezoelectric element attached to the panel, wherein the panel is configured to be deformed due to deformation of the piezoelectric element, and human-body vibration sound is transmitted to an object that is in contact with the deformed panel; and a cover member including a wall surface portion surrounding the piezoelectric element and a top surface portion extending from the wall surface portion, wherein the cover member is attached to the panel, and the piezoelectric element is disposed in space defined by the panel and the cover member.

In one of preferred embodiments, the space is filled with curable resin.

Yet another aspect of the present disclosure resides in a method of manufacturing an electronic device including: a housing; a panel attached to the housing; a piezoelectric element attached to the panel; and a frame member surrounding the piezoelectric element, wherein the panel is configured to be deformed due to deformation of the piezoelectric element, and human-body vibration sound is transmitted to an object that is in contact with the deformed panel. The method includes the step of: covering a surface of the piezoelectric element that opposes to another surface of the piezoelectric element attached to the panel with curable resin, by attaching the frame member to the panel and pouring the curable resin into a substantially box-shaped mold defined by the panel and an inner wall surface of the frame member and curing the curable resin.

Yet another aspect of the present disclosure resides in a method of manufacturing an electronic device including: a housing; a panel attached to the housing; a frame member including a wall surface portion surrounding the piezoelectric element and a bottom surface portion extending from the wall surface portion; and a piezoelectric element attached to the frame member, wherein the panel is configured to be deformed due to deformation of the piezoelectric element, and human-body vibration sound is transmitted to an object that is in contact with the deformed panel. The method includes the step of: covering a surface of the piezoelectric element that opposes to another surface of the piezoelectric element attached to the frame member with curable resin, by pouring the curable resin into a substantially box-shaped mold defined by the wall surface portion and the bottom surface portion of the frame member and curing the curable resin.

In one of preferred embodiments, an edge area of the bottom surface portion is attached to the panel by a first joining member, and the bottom surface portion is provided, in at least a part thereof, with a through hole through which the curable resin is filled to space defined between the panel and the bottom surface portion.

Yet another aspect of the present disclosure resides in a unit, including: a piezoelectric element; and a protective member attached to a predetermined surface of the piezoelectric element, wherein when another surface of the piezoelectric element that is different from the predetermined surface of the piezoelectric element is attached to a predetermined plate-shaped member, the plate-shaped member is deformed due to deformation of the piezoelectric element, and human-body vibration sound is transmitted to an object that is in contact with the deformed plate-shaped member, and a surface of the protective member that opposes to another surface of the protective member attached to the piezoelectric element has a convex curved shape.

Yet another aspect of the present disclosure resides in a unit, including: a first plate-shaped member; and a piezoelectric element attached to the first plate-shaped member, wherein, when a surface of the first plate-shaped member that opposes to another surface of the first plate-shaped member attached with the piezoelectric element is attached to a second plate-shaped member that is different from the first plate-shaped member, the second plate-shaped member is deformed due to deformation of the piezoelectric element, and human-body vibration sound is transmitted to an object that is in contact with the deformed second plate-shaped member; and a protective member attached to a surface of the piezoelectric element that opposes to another surface of the piezoelectric element attached to the first plate-shaped member, wherein a surface of the protective member that opposes to another surface of the protective member attached to the piezoelectric element has a convex curved shape.

Yet another aspect of the present disclosure resides in a unit, including: a box-shaped member; and a piezoelectric element attached to a bottom surface portion on an inner side of the box-shaped member, wherein when a surface at bottom of the box-shaped member that opposes to another surface at bottom of the box-shaped member attached with the piezoelectric element is attached to a predetermined plate-shaped member, the plate-shaped member is deformed due to deformation of the piezoelectric element, and human-body vibration sound is transmitted to an object that is in contact with the deformed plate-shaped member, and at least a part of the piezoelectric element is covered by curable resin that has been poured into the box-shaped member and cured.

Yet another aspect of the present disclosure resides in an electronic device, including: a panel; a piezoelectric element; a housing to which the panel is attached; and an intermediate member attached to the panel and the piezoelectric element and disposed between the piezoelectric element and the panel, wherein the panel is configured to be deformed due to deformation of the piezoelectric element, and human-body vibration sound is transmitted to an object that is in contact with the deformed panel, and in a predetermined area of the intermediate member that includes at least an area located right below the piezoelectric element in a direction in which the panel, the intermediate member, and the piezoelectric element are laminated, the intermediate member is attached to the panel by a first joining member, and in at least a part of a periphery of the predetermined area, the intermediate member is attached to the panel by a second joining member that is more flexible than the first joining member.

In one of preferred embodiments, the intermediate member is attached to one end side of the panel, and the second joining member is disposed on an opposite side to the one end side of the panel in an area over which the intermediate member is attached to the panel.

In one of preferred embodiments, the first joining member includes a curable resin.

In one of preferred embodiments, the second joining member includes a double-sided adhesive tape.

In one of preferred embodiments, the electronic device further includes a protective member attached to a surface of the piezoelectric element that opposes to another surface of the piezoelectric element attached to the intermediate member, wherein a surface of the protective member that opposes to another surface of the protective member attached to the piezoelectric element has a convex curved shape.

In one of preferred embodiments, the protective member covers both the surface of the piezoelectric element that is attached with the protective member and side surfaces extending from the surface of the piezoelectric element that is attached with the protective member.

In one of preferred embodiments, a surface of the intermediate member that is attached with the panel or the piezoelectric element is provided with a groove.

Yet another aspect of the present disclosure resides in a method of manufacturing an electronic device including: a panel; a piezoelectric element; a housing to which the panel is attached; an intermediate member attached to the panel and the piezoelectric element and disposed between the piezoelectric element and the panel; and a joining member used to attach the intermediate member to the panel, wherein the panel is configured to be deformed due to deformation of the piezoelectric element, and human-body vibration sound is transmitted to an object that is in contact with the deformed panel, space is defined between the panel, the intermediate member, and the joining member, and the space is provided with a first hole through which the space communicates with outside of the space. The method includes the step of: filling curable resin to the space from the first hole.

In one of preferred embodiments, the space is further provided with a second hole through which the space communicates with the outside, the second hole being different from the first hole, and an adhesive agent is filled to the space through the first hole, and air that is present in the space is expelled to the outside through the second hole.

In one of preferred embodiments, the piezoelectric element has a rectangular shape, the joining member is attached to both edge portions of a predetermined surface of the piezoelectric element along a longitudinal direction thereof, the space has a substantially rectangular shape, the first hole is provided on one end of the space in the longitudinal direction, and the second hole is provided on another end opposing to the one end of the space in the longitudinal direction.

In one of preferred embodiments, the intermediate member includes a bottom surface portion to which the piezoelectric element is attached and a wall surface portion standing from the bottom surface portion, and the curable resin is poured into box-shaped inner space defined by the bottom surface portion and the wall surface portion and cured, and a surface of the piezoelectric element that opposes to another surface of the piezoelectric element attached to the intermediate member is covered by the curable resin.

Yet another aspect of the present disclosure resides in a unit, including: a first plate-shaped member; and a piezoelectric element attached to the first plate-shaped member, wherein when a surface of the first plate-shaped member that opposes to another surface of the first plate-shaped member attached with the piezoelectric element is attached to a second plate-shaped member that is different from the first plate-shaped member, the second plate-shaped member is deformed due to deformation of the piezoelectric element, and human-body vibration sound is transmitted to an object that is in contact with the deformed second plate-shaped member, and in a predetermined area that includes at least an area located right below the piezoelectric element in a direction in which the piezoelectric element and the first plate-shaped member are laminated, the piezoelectric element is attached to the first plate-shaped member by a first joining member, and in at least a part of a periphery of the predetermined area, the piezoelectric element is attached to the first plate-shaped member by a second joining member that is more flexible than the first joining member.

Yet another aspect of the present disclosure resides in a unit, including: a box-shaped member; and a piezoelectric element attached to a bottom surface portion on an inner side of the box-shaped member, wherein when a surface at bottom of the box-shaped member that opposes to another surface at bottom of the box-shaped member attached with the piezoelectric element is attached to a predetermined plate-shaped member, the plate-shaped member is deformed due to deformation of the piezoelectric element, and human-body vibration sound is transmitted to an object that is in contact with the deformed plate-shaped member, and in a predetermined area that includes at least an area located right below the piezoelectric element in a direction in which the piezoelectric element and the bottom surface portion of the box-shaped member are laminated, the piezoelectric element is attached to the box-shaped member by a first joining member, and in at least a part of a periphery of the predetermined area, the piezoelectric element is attached to the box-shaped member by a second joining member that is more flexible than the first joining member.

In one of preferred embodiments, the unit further includes a protective member attached to a surface of the piezoelectric element that opposes to another surface of the piezoelectric element attached to the panel.

In one of preferred embodiments, a surface of the protective member that opposes to another surface of the protective member attached to the piezoelectric element has a convex curved shape.

Advantageous Effect

The present disclosure provides a unit, an electronic device, and a method of manufacturing the electronic device, all of which are capable of preventing excessive deformation of the piezoelectric element and preventing damage to the piezoelectric element caused by external force.

DETAILED DESCRIPTION

Preferred embodiments of the present disclosure will be described below with reference to the accompanying drawings.FIG. 1is a function block diagram of an electronic device1according to one of embodiments of the present disclosure. The electronic device1, which may be a mobile phone (e.g., a smartphone), includes a panel10(as one example of a mounting member), a display20, a piezoelectric element30, an input unit40, and a controller50.

The panel10may be a touch panel that is configured to detect a contact or a cover panel that protects the display20. The panel10may be made of, for example, glass, a synthetic resin such as acryl, and sapphire. Sapphire herein refers to a crystallized form of aluminum oxide (Al2O3) manufactured commercially. The panel10may have a flat plate shape or a curved shape. The panel having a curved shape may include the one having a concave shape dented in a middle portion on a surface forming an outer side of the electronic device1and also having a flat shape on a surface forming an inner side of the electronic device1. Such a panel provides good usability because the concave surface of the panel fits easily to the temple of a user when the user presses the electronic device1against the temple to make a call. On the other hand, the surface of the panel10that is located on the inner side of the electronic device1is flat, and accordingly, even a non-flexible plate-shaped display20may be easily attached to the panel10. The panel10preferably has a plate shape. The panel10may be a flat plate or a curved panel having a gradually inclined surface. When the panel10is a touch panel, the panel10detects a contact made by a finger of a user, a pen, a stylus pen, or the like. The touch panel may detect a contact using any type, such as a capacitive type, a resistive film type, a surface acoustic wave type (or an ultrasonic type), an infrared type, an electromagnetic induction type, and a load detection type.

The display20is a display device such as a liquid crystal display, an organic EL display, and an inorganic EL display. The display20may be a flexible display. The display20is disposed on the back surface of the panel10. The display20may be disposed on the back surface of the panel10by using a joining member (e.g., an adhesive agent). The display20may also be supported by the housing of the electronic device1in a manner such that the display20is spaced apart from the panel10. Alternatively, in a preferred embodiment, the display20may be joined to the back surface of the panel10by a joining member (e.g., an adhesive agent). The joining member may be an elastic resin, such as an optical elastic resin, with a controlled refractive index for light transmitted therethrough. The display20displays various information through the joining member and the panel10.

The piezoelectric element30is an element that is configured to undergo expansion and contraction or bending (flexure) in accordance with an electromechanical coupling factor of a constituent material in response to an electric signal (voltage) applied thereto. As a material of the element, ceramic, crystal, and so forth may be used. The piezoelectric element30may be a unimorph, a bimorph, or a laminated-type piezoelectric element. The laminated-type piezoelectric element includes a laminated-type unimorph element in which (e.g., 16 or 24 layers of) unimorph are laminated or a laminated-type bimorph element in which (e.g., 16 or 24 layers of) bimorph are laminated. The laminated-type piezoelectric element is configured, for example, by a laminated structure of a plurality of dielectric layers made of lead zirconate titanate (PZT) and electrode layers each disposed between adjacent ones of the dielectric layers. The laminated-type piezoelectric element is bent and displaced in a direction in which the layers are laminated, namely, in the thickness direction, in response to an electric signal (voltage) applied thereto. Unimorph undergoes expansion and contraction in response to an electric signal (voltage) applied thereto, and bimorph undergoes bending in response to an electric signal (voltage) applied thereto.

The piezoelectric element30is disposed on the back surface of the panel10(a surface of an inner side of the electronic device1). The piezoelectric element30is attached to the panel10by a joining member (e.g., a double-sided adhesive tape). The piezoelectric element30may also be attached to the panel10via an intermediate member (e.g., a sheet metal). The piezoelectric element30is at a predetermined distance from a surface of an inner side of a housing60in a state where the piezoelectric element30is disposed on the back surface of the panel10. Preferably, the piezoelectric element30remains at a predetermined distance from the surface of the inner side of the housing60even in a state where the piezoelectric element30undergoes expansion and contraction or flexture. That is to say, the distance between the piezoelectric element30and the surface of the inner side of the housing60is preferably greater than a maximum amount of deformation of the piezoelectric element30.

The input unit40is configured to receive an operation input from the user and is configured by, for example, an operation button (an operation key). When the panel10is the touch panel, the panel10is also capable of receiving an operation input from the user by detecting a contact made by the user.

The controller50is a processor configured to control the electronic device1. The control unit50applies, to the piezoelectric element30, a predetermined electric signal (voltage corresponding to a sound signal). When the control unit50applies an electric signal to the piezoelectric element30, the piezoelectric element30is bent and displaced in the thickness direction. At this time, the panel10attached with the piezoelectric element30is deformed in conjunction with displacement of the piezoelectric element30, thus resulting in the vibration of the panel10. The panel10thus generates air conduction sound. The panel10also transmits human-body vibration sound to an object that is in contact with the panel10. Examples of the object include a part of a user's body (e.g., a cartilaginous portion of an external ear). For example, the control unit50may apply, to the piezoelectric element30, an electric signal corresponding to a sound signal representing voice of the party on the phone, to generate air conduction sound and human-body vibration sound that correspond to the sound signal. The sound signal may represent a phone melody, music including a tune, or the like. The sound signal according to the electric signal may be based on music data stored in an internal memory of the electronic device1or may be reproduced according to music data stored in an external server and the like over the network. The voltage that the control unit50applies to the piezoelectric element30may be ±15 V which is greater than ±5 V, that is, a voltage to be applied to a so-called panel speaker configured for sound conduction not using human-body vibration sound but using air conduction sound. With the above configuration, even when the user forcefully presses the panel10against a user's body with force greater than or equal to 3 N or so (e.g., force ranging from 5 N to 10 N), the piezoelectric element30causes vibration of the panel10. As a result, human-body vibration sound which is transmitted through a part of the user's body is generated. Note that an amount of the application voltage is appropriately adjustable according to how tightly the panel10is fixed to the housing or a supporting member or according to a capability of the piezoelectric element30. When the control unit50applies an electric signal to the piezoelectric element30, the piezoelectric element30undergoes expansion and contraction or flexture in the longitudinal direction. At this time, the panel10attached with the piezoelectric element30is deformed in conjunction with expansion and contraction or flexture of the piezoelectric element30, thus resulting in the vibration of the panel10. The panel10undergoes flexure in response to expansion and contraction or flexture of the piezoelectric element30. The panel10is bent directly by the piezoelectric element30. The state in which the “panel10is bent directly by the piezoelectric element” differs from a phenomenon in which the panel is deformed when a certain area of the panel is vibrated due to inertial force of a piezoelectric actuator including the piezoelectric element provided in a casing as adopted in an existing panel speaker. The state in which the “panel10is bent directly by the piezoelectric element” refers to a state in which the panel is bent directly by expansion and contraction or bending (flexure) of the piezoelectric element via the joining member or via the joining member and a reinforcing member80which is later described. Thus, the panel10generates air conduction sound, and the panel10also generates human-body vibration sound that is transmitted through a part of the body when the user places the part of the body (e.g., the cartilaginous portion of the external ear) in contact with the panel10. For example, the control unit50may apply, to the piezoelectric element30, an electric signal corresponding to a sound signal representing voice of the party on the phone or the like, to generate air conduction sound and human-body vibration sound that correspond to the sound signal. The sound signal may represent a phone melody, music including a tune, or the like. The sound signal according to the electric signal may be based on music data stored in an internal memory of the electronic device1or may be reproduced according to music data stored in an external server and the like over the network.

The vibration is caused in an area of the panel10where the piezoelectric element30is disposed and in other areas of the panel10that are away from the area where the piezoelectric element30is disposed. The panel10includes, in the areas vibrated, a plurality of portions that is configured to vibrate in a direction intersecting with a main surface of the panel10, and in each of the plurality of portions, a value indicating an amplitude of the vibration transitions over time from plus to minus or vice versa. The panel10is vibrated in a manner such that areas with relatively large amplitude of vibration and areas with relatively small amplitude of vibration are seemingly distributed randomly across the panel10at a certain moment. In other words, the vibration of a plurality of wavelengths is detected across all areas of the panel10. In order to prevent the aforementioned vibration of the panel10from being attenuated even when the user forcefully presses the panel10against the user's body with force ranging, for example, from 5 N to 10 N, the voltage that the control unit50applies to the piezoelectric element30may be ±15 V. The above configuration allows the user to listen to sound while placing the ear in contact with the areas of the panel10that are away from the area where the piezoelectric element30is disposed.

The panel10may be substantially as large as the user's ear. As illustrated inFIG. 2, the panel10may also be larger than the user's ear. In this case, when the user listens to sound, the whole ear tends to be covered by the panel10of the electronic device1. As a result, ambient sound (noise) is prevented from entering through an external auditory canal. It is suffice for the vibration to occur in an area of the panel10that is larger than an area having a length corresponding to a distance from an inferior crus of antihelix (i.e., an inferior crus anthelicis) to an antitragus and a width corresponding to a distance from a tragus to an antihelix. It is preferable for the vibration to occur in an area of the panel10that is larger than an area having a length corresponding to a distance from a portion of a helix that is near a superior crus of antihelix (i.e., a superior crus anthelicis) to an auricular lobule and a width corresponding to a distance from the tragus to a portion of the helix that is near the antihelix. A length direction herein refers to a longitudinal direction2aalong which the panel10extends, and the piezoelectric element30is disposed closer to one end portion relative to a middle of the panel10in the longitudinal direction2a. A width direction refers to a direction2bintersecting with the longitudinal direction. The areas having the above lengths and widths may have an oblong shape or an elliptical shape with as a major axis corresponding to the length and a minor axis corresponding to the width. Average ear size of the Japanese may be seen from, for example, the Japanese Body Dimension Database (1992-1994) distributed by the Research Institute of Human Engineering for Quality Life (HQL). The panel10with a size greater than the average ear size of the Japanese would be generally capable of covering a whole ear of a foreigner as well.

With the aforementioned dimension and shape, the panel10is capable of covering the user's ear, which offers tolerance to misalignment when the user presses the panel10to the ear.

The above electronic device1is capable of transmitting, to the user, air conduction sound and human-body vibration sound, which is transmitted through a part of the user's body (e.g., the cartilaginous portion of the external ear), by the vibration of the panel10. Accordingly, when the panel10outputs sound at substantially the same volume level as an existing dynamic receiver, less amount of sound propagates to an external environment of the electronic device1due to the vibration of air resulting from the vibration of the panel10, compared to cases of the dynamic receiver. Accordingly, the electronic device1is well-suited for a situation where a recorded message is listened to on the train and the like, for example.

The electronic device1generates sound which is transmitted to an inner part of the human body by the vibration of the panel10generated by the piezoelectric element30. The sound to be transmitted to an inner part of the human body passes through a soft tissue of the human body (e.g., the cartilage) to vibrate a middle ear or an inner ear. The above electronic device1transmits human-body vibration sound by the vibration of the panel10. Furthermore, even when the user wears an earphone or a headphone, the user is able to listen to sound though the earphone or the headphone and a portion of the body by placing the electronic device1in contact with the earphone and the headphone.

The above electronic device1transmits sound to the user by the vibration of the panel10. Accordingly, in cases where the electronic device1is not provided with an additional dynamic receiver, it is not necessary to provide the housing with an opening (i.e., a sound discharge opening) for sound transmission. As a result, the waterproof structure of the electronic device is simplified. When the electronic device1is provided with a dynamic receiver, the sound discharge opening may be closed by a member that passes air through and blocks liquid. The member that passes air through and blocks liquid may be Gore-Tex™.

First Embodiment

FIGS. 3A to 3Billustrate a housing configuration of the electronic device1according to the first embodiment.FIG. 3Ais a front view, andFIG. 3Bis a sectional view taken along a line b-b ofFIG. 3A. The electronic device1illustrated inFIGS. 3A and 3Bis a smartphone in which a touch panel, i.e., a glass plate, is mounted as the panel10on a front surface of a housing60(e.g., a metal or a resin casing). The panel10and the input unit40are supported by the housing60, and the display20and the piezoelectric element30are each adhered to the panel10by a joining member70. The joining member70may an adhesive agent, a double-sided adhesive tape, or the like having thermosetting properties, ultraviolet-curable properties, or the like. For example, the joining member70may be an optical elastic resin, which is a colorless and transparent ultraviolet-curable acrylic adhesive agent. The panel10, the display20, and the piezoelectric element30each have a substantially rectangular shape.

The display20is disposed in substantially a middle of the panel10in a short-side direction thereof. The piezoelectric element30is disposed near an end portion of the panel10in the longitudinal direction of the panel10at a predetermined distance from the end portion in a manner such that the longitudinal direction of the piezoelectric element30extends along a short side of the panel10. The display20and the piezoelectric element30are disposed side by side in a direction parallel to a surface of an inner side of the panel10.

A description is given of a configuration in the vicinity of the piezoelectric element30of the electronic device1according to the first embodiment with reference toFIGS. 4 to 9. As illustrated inFIGS. 4 to 9, a Flexible Printed Circuit (FPC)25is connected to the piezoelectric element30. The FPC25conveys an electric signal applied from the controller50to the piezoelectric element30. In other words, an electric signal from the controller50is conveyed to the piezoelectric element30via the FPC25.

The FPC25includes a base25a, signal lines25band25c, and a cover lay25dthat are laminated in the stated order. The base25aand the cover lay25dare formed by using resin, such as polyimide. The base25ais a base of the FPC25and is one example of a resin member. The signals25band25care formed by using, for example, copper foil or bronze foil. The base25aand the signal lines25band25care adhered by using an adhesive agent, such as thermosetting resin (which is not illustrated), and the signal lines25band25cand the cover lay25dare similarly adhered.

FIG. 4is a perspective view illustrating a state in which the FPC25and the piezoelectric element30are connected.FIG. 5illustrates the FPC25and the piezoelectric element30ofFIG. 4in a thickness direction of the FPC25or the piezoelectric element30. As illustrated inFIG. 4, the piezoelectric element30has a long shape. The piezoelectric element30has a flat plate shape. The piezoelectric element30includes the first main surface30aand the second main surface30d. The FPC25is electrically connected to the piezoelectric element30mainly in an end area of the first main surface30aof the piezoelectric element30in the longitudinal direction. InFIG. 4, the FPC25is electrically connected to the piezoelectric element30in the end portion located on the left in the longitudinal direction of the piezoelectric element30. A description is given later in detail about a connection configuration between the FPC25and the piezoelectric element30.

In an area where the FPC25is connected to the piezoelectric element30, the base25aof the FPC25has a larger thickness than the remaining area of the base25a. For example, an area of the base25athat is not connected to the piezoelectric element30may have a thickness of approximately 0.03 mm, while an area of the base25athat is located near the area connected to the piezoelectric element30may have a thickness of approximately 0.4 mm. The base25amay also have the constant thickness in the area not connected to the piezoelectric element30and in the area located near the area connected to the piezoelectric element30. By imparting a relatively large thickness to the area of the base25athat is located near the area where the FPC25is connected to the piezoelectric element30, separation of the FPC25and the piezoelectric element30is prevented when, for example, external force is applied to the connected areas of the FPC25and the piezoelectric element30.

The area of the base25athat has a relatively large thickness covers the first main surface30aof the piezoelectric element30. The area of the base25athat has a relatively large thickness covers substantially the entire first main surface30aof the piezoelectric element30. The phrase “substantially the entire” or “the entire” first main surface30arefers to, for example, 80 percent or more of the whole first main surface30a. The above area of the base25, which prevents damage to the piezoelectric element30, does not need to cover the first main surface30acompletely. The area of the base25athat has a relatively large thickness extends to an end portion of the piezoelectric element30that opposes to the area of the piezoelectric element30connected with the FPC25in the longitudinal direction of the piezoelectric element30(i.e., the end portion of the piezoelectric element30that is located on the right in the longitudinal direction inFIG. 4). The second main surface30dof the piezoelectric element30is not covered by the base25a, and the second main surface30dis adhered to the panel10by using the joining member70.

FIGS. 6A and 6Billustrate the areas of the FPC25and the piezoelectric element30where both are connected.FIG. 6Aillustrates the area of the FPC25to be connected, as viewed from the side of the cover lay25d.FIG. 6Billustrates the area of the piezoelectric element30to be connected, as viewed from the side of the first main surface30a. As illustrated inFIG. 6A, in the area of the FPC25to be connected, a part of each of the signal lines25band25cis exposed from the cover lay25d. As illustrated inFIG. 6B, in the area of the piezoelectric element30that is to be connected, a plus electrode terminal30band a minus electrode terminal30care exposed from the first main surface30a. For connection between the FPC25and the piezoelectric element30, the signal line25bof the FPC25is connected to the plus electrode terminal30bof the piezoelectric element30, and the signal line25cof the FPC25is connected to the minus electrode terminal30cof the piezoelectric element30. The FPC25and the piezoelectric element30are adhered by a technique called Anisotropic Conductive Paste (ACP) connection or Anisotropic Conductive Film (ACF) connection which is later described.

With reference toFIGS. 7 and 8, a description is given of a connection configuration between the FPC25and the piezoelectric element30.FIG. 7illustrates the first example of the connection configuration between the FPC25and the piezoelectric element30.FIG. 8illustrates the second example of the connection configuration between the FPC25and the piezoelectric element30.

Firstly, with reference toFIG. 7, a description is given of the first example of the connection configuration, including the ACP connection or the ACF connection, between the FPC25and the piezoelectric element30. The ACP connection or the ACF connection uses an anisotropic conductive material100. The anisotropic conductive material100is composed mainly of a binder (an adhesive agent) in which conductive particles are mixed. The binder is a component used for mechanically fixing the areas to be connected, and the conductive particles are components serving to bring the opposing electrodes into electrical conduction. The binder is, for example, a synthetic rubber-based resin having thermosetting properties. The conductive particles include, for example, particles of resin, such as polystyrene, that are overlaid with gold. The conductive particles may also include metal cores, such as nickel, that are overlaid with gold, or metal cores per se.

The FPC25and the piezoelectric element30are connected by thermocompression bonding, during which these members are superposed with the aforementioned anisotropic conductive material100being disposed between the areas of the FPC25and the piezoelectric element30that are to be connected.FIG. 7illustrates a state in which the FPC25and the piezoelectric element30have been connected by thermocompression bonding.FIG. 7is a sectional view taken along a line VII-VII inFIG. 5. InFIG. 7, reference numeral100adenotes the binder (adhesive agent), and reference numeral100bdenotes a conductive particle. As a result of the thermocompression bonding, the signal lines25band25cof the FPC25are mechanically and electrically connected to the plus electrode terminal30band the minus electrode terminal30cof the piezoelectric element30by the conductive particles100bsandwiched therebetween. On the other hand, the binder, which is an insulator, maintains insulation between adjacent conductive particles100b.

InFIG. 7, the plus electrode terminal30band the minus electrode terminal30cof the piezoelectric element30are illustrated as electrically connected through the signal lines25band25cof the FPC25and the conductive particles100b. However, in practice, the signal lines25band25care disposed at a distance in a direction along the main surface of the piezoelectric element30(i.e., in a direction that is perpendicular to the sheet ofFIG. 7) as illustrated inFIG. 6A, and the signal line25bis connected to the plus electrode terminal30bbut not connected to the minus electrode terminal30c. Similarly, the signal line25cis connected to the minus electrode terminal30cbut not connected to the plus electrode terminal30b.

The base25aextends in the longitudinal direction of the piezoelectric element30from the vicinity of the area where the FPC25is connected to the piezoelectric element30. The base25acovers the first main surface30aof the piezoelectric element30.

In this way, according to the first example, substantially the entire first main surface30aof the piezoelectric element30is covered by the base25amade of, for example, resin such as polyimide. The above configuration prevents, when the electronic device1is dropped to the ground and the housing60is deformed, the deformed housing60from damaging the piezoelectric element30by colliding with the piezoelectric element30. Furthermore, since the plus electrode30band the minus electrode30cdisposed on the first main surface30aof the piezoelectric element30are covered by the insulative base25a, when a metal member (e.g., a sheet metal member or the like that supports a circuit substrate or the display20) is disposed in the vicinity of the piezoelectric element30in the housing60, the metal member is brought into conduction with the piezoelectric element30, and malfunction of the electronic device1is prevented.

Secondly, with reference toFIG. 8, a description is given of the second example of the connection configuration between the FPC25and the piezoelectric element30. A description of a part of the configuration that is similar to the first example is omitted, and different features are mainly described below.

The second example ofFIG. 8differs from the first example ofFIG. 7in the connection configuration between the signal line25cof the FPC25and the minus electrode terminal30cof the piezoelectric element30. As illustrated inFIG. 8, in the second example, the signal line25cof the FPC25extends to the vicinity of the end portion of the piezoelectric element30that is located on the right in the longitudinal direction of the piezoelectric element30(i.e., in a left and right direction inFIGS. 7 and 8). Furthermore, the minus electrode terminal30cis disposed in the vicinity of the end portion of the piezoelectric element30that is located on the right in the longitudinal direction thereof, and the minus electrode terminal30cis not disposed in the vicinity of the middle portion of the piezoelectric element30in the longitudinal direction and in the vicinity of the plus electrode30b. On the other hand, the plus electrode terminal30bis disposed in the vicinity of the end portion of the piezoelectric element30that is located on the left in the longitudinal direction. That is to say, connection between the FPC25and the piezoelectric element30is achieved between the signal line25band the plus electrode terminal30bon one end portion of the piezoelectric element30in the longitudinal direction thereof, and between the signal line25cand the plus electrode30con the other end portion in the longitudinal direction. Additionally, in the vicinity of the middle portion of the piezoelectric element30in the longitudinal direction thereof, the cover lay25dof the FPC25is located between the signal lines25band25cand the piezoelectric element30. Accordingly, the conductive particles100bcannot bring the FPC25into undesired conduction with the piezoelectric element30in the vicinity of the middle portion of the piezoelectric element30.

In this way, according to the second example, the plus electrode terminal30bof the piezoelectric element30is disposed in the vicinity of one end portion in the longitudinal direction, and the minus electrode terminal30cis located in the vicinity of the other end portion in the longitudinal direction. The above configuration prevents a short circuit between the plus electrode terminal30band the minus electrode terminal30cdue to the conductive particles100b. Furthermore, compared with the first example ofFIG. 7, an area of the first main surface30aof the piezoelectric element30over which the minus electrode terminal30cis disposed is reduced, and accordingly, flexure of the piezoelectric element30is facilitated.

Although inFIG. 8the minus electrode terminal30cis disposed only in the vicinity of the end portion of the piezoelectric element30that is located on the right in the longitudinal direction thereof and is not disposed in the vicinity of the middle portion of the piezoelectric element30in the longitudinal direction thereof and in the vicinity of the plus electrode terminal30b, the present embodiment is not limited to this example. The minus electrode terminal30conly needs to be disposed at a distance that is sufficient to prevent a short circuit between the minus electrode terminal30cand the plus electrode terminal30bdue to the conductive particles100bof the anisotropic conductive material, and the minus electrode terminal30cmay also be disposed in the vicinity of the middle portion of the piezoelectric element30in the longitudinal direction thereof and in the vicinity of the plus electrode terminal30b.

Thirdly, with reference toFIG. 9, a description is given of the third example of the connection configuration between the FPC25and the piezoelectric element30. A description of a part of the configuration that is similar to the first and the second example is omitted, and different features are mainly described below.

The connection configuration between the FPC25and the piezoelectric element30in the third example ofFIG. 9is different in the vicinity of the middle portion of the piezoelectric element30in the longitudinal direction thereof. As illustrated inFIG. 9, connection between the FPC25and the piezoelectric element30is achieved between the signal line25band the plus electrode terminal30bby the anisotropic conductive materials100on one end portion of the piezoelectric element30in the longitudinal direction thereof, and between the signal line25cand the plus electrode terminal30cby the anisotropic conductive materials100on the other end portion. Furthermore, a gap29is formed between the minus electrode terminal30cand the cover lay25din the vicinity of the middle portion of the piezoelectric element30in the longitudinal direction thereof. That is to say, the minus electrode terminal30cand the cover lay25dare disposed at a predetermined distance.

In this way, according to the third example, the FPC25and the piezoelectric element30are connected on both the end portions of the piezoelectric element30in the longitudinal direction thereof and not connected in the vicinity of the middle portion of the piezoelectric element30in the longitudinal direction thereof. The above configuration prevents the FPC25from interfering with deformation of the piezoelectric element30while maintaining electrical conduction therebetween and thus allows the piezoelectric element30to vibrate the panel10efficiently. The piezoelectric element30is deformed in response to voltage applied thereto as described above, and a part of the FPC25, such as a part of the FPC25that opposes to the vicinity of the middle portion of the piezoelectric element30in the longitudinal direction thereof, may be bent as long as the FPC25does not interfere with the deformation of the piezoelectric element30. The phrase “substantially the entire first main surface30aof the piezoelectric element30is covered by the FPC25” herein encompasses both the configuration as illustrated in the first and the second example in which substantially the entire main surfaces of these elements are adhered by the anisotropic conductive material100and the configuration as illustrated in the third example in which these elements are connected only on both the end portions of the piezoelectric element30in the longitudinal direction thereof. In the gap29, an elastic member, such as sponge, may be disposed.

In the following, a description is given of the first modification of the electronic device1according to the present disclosure with reference toFIG. 10.FIG. 10illustrates the FPC25and the piezoelectric element30according to the first modification. As illustrated inFIG. 10, the FPC25is connected to the piezoelectric element30similarly to the examples ofFIGS. 7 and 8and also connected to an electronic member55. The FPC25extends further from an end portion of the piezoelectric element30in the longitudinal direction thereof. The electronic member55is connected with an end portion of the FPC25. The electronic member55is, for example, a light intensity sensor, a proximity sensor, a camera, or an infrared communicator. The FPC25includes, in addition to the signal lines25band25cthat are connected to the piezoelectric element30, a signal line connected to the electronic member55.

By thus further extending the FPC25covering the entire first main surface30aof the piezoelectric element30and disposing the electronic member55in the end of the extended portion (herein after, called “the extension”), the piezoelectric element30and the electronic member55are connected to a circuit substrate (which is not illustrated) by using the single FPC25, and the number of elements is reduced. Additionally, the FPC25is also deformed due to deformation of the piezoelectric element30, and the deformation of the FPC25might be propagated to the electronic member55, thus vibrating the electronic member55. In this case, the magnitude of the vibration of the electronic member55is reduced by covering the electronic member55with an elastic member, such as sponge. The extension of the FPC25may also be further extended to protect the extension against tension. In this case, vibration caused by the deformation of the FPC25is prevented from being propagated to the electronic member.

In the electronic device1described above, the second main surface30dof the piezoelectric element30is adhered to the panel10by the joining member70, and the first main surface30aof the piezoelectric element30that opposes to the second main surface30dis covered by the base25aof the FPC25. That is to say, the piezoelectric element30is disposed between the panel10and the FPC25. However, the configuration of the electronic device1according to the present disclosure is not limited to this example.

With reference toFIG. 11, a description is given of the second modification of the electronic device1.FIG. 11illustrates the panel10, the FPC25, and the piezoelectric element30according to the second modification. In the present modification, the FPC25is disposed between the panel10and the piezoelectric element30. For example, the base25aof the FPC25is connected to the panel10by the joining member70, and the cover lay25dof the FPC25is connected to the piezoelectric element30by the aforementioned ACF connection.

In the present modification, the FPC25, which includes the base made of resin such as polyimide, is disposed between the panel10and the piezoelectric element30. The above configuration allows, when, for example, the electronic device1is dropped to the ground and the resulting external impact is propagated to the piezoelectric element30though the panel10, the FPC25to mitigate the external impact, thus preventing damage to the piezoelectric element30.

A surface of the piezoelectric element30that opposes to another surface of the piezoelectric element30attached to the FPC25is exposed in the inside of the electronic device1. However, the exposed surface may also be covered by a protective member made of resin or the like. This configuration, similarly to the aforementioned example, prevents damage to the piezoelectric element30caused when the deformed housing60collides with the piezoelectric element30due to dropping of the electronic device1.

Although the FPC25in the present modification is described as attached to the panel10by the joining member70, the present modification is not limited to this example. The FPC25may also be attached to the panel10by the aforementioned ACF connection. In this case, the FPC25may further include a signal line other than the signal lines25band25cconnected to the piezoelectric element30, and the further signal line may be connected to an electrode terminal provided in the panel10. The above configuration allows an electric signal to be applied to not only the piezoelectric element30but also the panel10through the FPC25.

The FPC25and the piezoelectric element30may also be connected by a solder member, not by the ACF connection.

The first example, the second example, and the modifications which have been described with reference toFIGS. 1 to 11may be combined appropriately.

FIG. 12illustrates one example of the vibration of the panel10of the electronic device1according to the first embodiment. In the electronic device1according to the first embodiment, the display20is attached to the panel10. Accordingly, the lower portion of the panel10is less likely to vibrate compared to the upper portion of the panel10attached with the piezoelectric element30. As a result, in the lower portion of the panel10, sound leakage due to the vibration occurring in the lower portion of the panel10is reduced. The panel10in the upper portion thereof is bent directly by the piezoelectric element30, and the vibration in the lower portion is attenuated compared to the vibration in the upper portion. The panel10is bent by the piezoelectric element30in a manner such that a portion of the panel10directly above the piezoelectric element30protrudes relative to neighboring portions of the panel10in a long-side direction of the piezoelectric element30. The panel10is also bent by the piezoelectric element30in a manner such that a portion of the panel10directly above the piezoelectric element30protrudes relative to neighboring portions of the panel10in a long-side direction of the panel10.

As described above, according to the electronic device1of the present embodiment, the panel10is deformed due to deformation of the piezoelectric element30attached to the back surface of the panel10, and air conduction sound and human-body vibration sound are transmitted to an object that is in contact with the deformed panel10. In conjunction with the deformation of the piezoelectric element30, the FPC25is also deformed. As a result, air conduction sound and human-body vibration sound are transmitted to the user without having to protrude the vibration body from an outer surface of the housing60. Accordingly, usability of the electronic device is improved compared to such an electronic device as described in Patent Literature 1 (Japanese Patent Application Publication No. 2005-348193), by which the user places the vibration body, which is significantly small compared to the housing, in contact with the body. Furthermore, since there is no need for pressing the user's ear to the piezoelectric element itself, the piezoelectric element30itself is less likely to damage. Moreover, although the user tends to drop a terminal device while vibration is generated when the housing60, not the panel10, is deformed, vibrating the panel10makes it unlikely to occur.

The piezoelectric element30is joined to the panel10by the joining member70. The above configuration allows attachment of the piezoelectric element30to the panel10without limiting flexibility of deformation of the piezoelectric element30significantly. The joining member70may be an adhesive agent that is not thermosetting. This provides an advantage that contraction due to a thermal stress is less likely to occur between the piezoelectric element30and the panel10during curing. The joining member70may also be a double-sided adhesive tape. This provides an advantage that a contraction stress, which often occurs when an adhesive agent is used, is less likely to be applied between the piezoelectric element30and the panel10.

Second Embodiment

FIGS. 13A to 13Cillustrate a housing configuration of the electronic device1according to the second embodiment.FIG. 13Ais a front view,FIG. 13Bis a sectional view taken along a line b-b inFIG. 13AandFIG. 13Cis a sectional view taken along a line c-c inFIG. 13A. The electronic device1illustrated inFIGS. 13A to 13Cis a foldable mobile phone in which a cover panel (e.g., an acryl plate), which serves as the panel10and is configured to cover the display20, is provided on a front surface of the upper-side housing60. In the second embodiment, the reinforcing member80is disposed between the panel10and the piezoelectric element30. The reinforcing member80is, for example, a resin plate, a sheet metal, or a resin plate including glass fiber. That is to say, in the electronic device1according to the second embodiment, the piezoelectric element30and the reinforcing member80are adhered by the joining member70, and the reinforcing member80and the panel10are adhered by the joining member70. Furthermore, in the second embodiment, the display20is not adhered to the panel10but supported by the housing60. That is to say, in the electronic device1according to the second embodiment, the display20is spaced apart from the panel10, and the display20is adhered to a supporting portion90, i.e., a part of the housing60, by the joining member70. The supporting portion90is not limited to be configured as the part of the housing60and may be formed by metal, resin, or the like, as a member independent from the housing60.

FIG. 14illustrates one example of the vibration of the panel10of the electronic device1according to the second embodiment. In the electronic device1according to the second embodiment, the panel10is the acryl plate with lower rigidity compared to a glass plate, and moreover, the display20is not adhered to the back surface of the panel10. Accordingly, amplitude generated by the piezoelectric element30is larger than cases of the electronic device1according to the first embodiment illustrated inFIG. 11. The vibration is caused in an area of the panel10where the piezoelectric element30is disposed and in areas of the panel10that are away from the disposed area. Accordingly, the user is able to hear air conduction sound transmitted through air and to hear human-body vibration sound by placing the ear in contact with any position of the panel10.

As described above, according to the electronic device1of the present embodiment, the reinforcing member80and the panel10are deformed due to deformation of the piezoelectric element30attached to the panel10via the reinforcing member80, and air conduction sound and human-body vibration sound are transmitted to an object that is in contact with the deformed panel10. Accordingly, air conduction sound and human-body vibration sound are transmitted to the user without the need for pressing the vibration body itself to the ear. Furthermore, the piezoelectric element30is attached to the surface of the panel10on the inner side of the housing60. Accordingly, air conduction sound and human-body vibration sound are transmitted to the user without having to protrude the vibration body from the outer surface of the housing60. Moreover, the deformation occurs in the area of the panel10where the piezoelectric element30is disposed and in other areas of the panel10, for transmission of air conduction sound and human-body vibration sound. Accordingly, the user is able to hear air conduction sound transmitted through air and to hear human-body vibration sound by placing the ear in contact with any position of the panel10.

Furthermore, disposing the reinforcing member80between the piezoelectric element30and the panel10makes it unlikely that, when, for example, the panel10is applied with an external force, the applied external force will be conveyed to the piezoelectric element30and damage the piezoelectric element30. Even when the panel10is forcefully pressed against the human body, the attenuation in the vibration of the panel10is reduced. Moreover, owing to the reinforcing member80disposed between the piezoelectric element30and the panel10, a resonance frequency of the panel10is decreased, and sound characteristics in a low frequency range are improved. Note that instead of the reinforcing member80a plate-shaped weight may be attached to the piezoelectric element30by the joining member70.

Third Embodiment

FIGS. 15A and 15Billustrate a configuration of the electronic device1according to the third embodiment of the present disclosure.FIG. 15Ais a front view, andFIG. 15Bis a sectional view taken along a line Y-Y inFIG. 15A. The electronic device1illustrated inFIGS. 15A and 15Bis a smartphone in which a touch panel, i.e., a glass plate, is mounted as the panel10on the front surface of the housing60(e.g., a metal or a resin casing). The panel10is joined to the housing60by the joining member70, and thus, attached to the housing60. The joining member70herein is, for example, an adhesive agent, a double-sided adhesive tape, or the like. The display20and the piezoelectric element30are each adhered and attached to the panel10by the joining member70. Examples of the joining member70that may be preferably used to attach the display20to the panel10include an optical elastic resin, which is a colorless and transparent ultraviolet-curable acrylic adhesive agent. Examples of the joining member70that may be preferably used to attach the piezoelectric element30to the panel10include a waterproof double-sided adhesive tape and an adhesive agent having thermosetting properties, ultraviolet-curable properties, or the like. The input unit40is attached to the housing60, similarly to the panel10. The panel10, the display20, and the piezoelectric element30each have a substantially rectangular shape.

The display20is disposed in substantially the middle of the panel10in the short-side direction thereof. The piezoelectric element30is disposed near the end portion of the panel10in the longitudinal direction of the panel10at a predetermined distance from the end portion in a manner such that the longitudinal direction of the piezoelectric element30extends along the short side of the panel10. The display20and the piezoelectric element30are disposed side by side in the direction parallel to the surface of the inner side of the panel10.

According to the electronic device1of the present embodiment with the above configuration, the panel10is deformed due to deformation of the piezoelectric element30attached to the back surface of the panel10, and air conduction sound and vibration sound are transmitted to an object that is in contact with the deformed panel10.

FIG. 16illustrates one example of the vibration of the panel10of the electronic device1according to the third embodiment. As illustrated in the figure, in the electronic device1according to the present embodiment, the piezoelectric element30is attached to the upper portion of the panel10, and the display20is attached to the lower portion of the panel10relative to the upper portion. The panel10is bent by the piezoelectric element30in a manner such that a portion of the panel10directly above the piezoelectric element30protrudes relative to neighboring portions of the panel10in the long-side direction2aof the panel10. On the other hand, the lower portion of the panel10that is attached with the display20is less likely to vibrate compared to the upper portion of the panel10that is attached with the piezoelectric element30. As a result, the lower portion of the panel10provides less sound leakage due to the vibration occurring in the lower portion of the panel10.

The above electronic device1transmits sound to the user by the vibration of the panel10. In this regard, compared with cases where the piezoelectric element30is attached to the housing60to vibrate the housing60, the user might drop the electronic device due to the vibration of the housing60during voice communication when the user holds the electronic device in the hand (since during voice communication the user usually holds the housing portion of the electronic device). In contrast, the electronic device1, which vibrates the panel10, hardly poses such a problem. Of course, however, the piezoelectric element30may also be attached to the housing60when the piezoelectric element30does not vibrate greatly.

With reference toFIG. 15Bagain, a protective member85is attached to a surface (hereinafter, called “the second main surface”) of the piezoelectric element30that opposes to another surface (hereinafter, called “the first main surface”) of the piezoelectric element30attached to the panel10. The protective member85includes an elastic member of, for example, organic synthetic rubber, a representative of which includes polybutadiene-based, nitrile-based, and chloroprene-based synthetic rubber, and inorganic synthetic rubber, such as silicone. The protective member85may also be curable resin having thermosetting properties, thermoplasticity, moisture curable properties, ultraviolet-curable properties, or the like. The protective member85may also include a composite of an organic material and an inorganic material (or metal). One example is a composite member (reinforced resin) obtained by mixing glass fiber, metallic fiber, carbon fiber, or the like into a polyimide-based resin as the base material. The strength, rigidity, and elasticity of the composite member may be controlled appropriately in accordance with the content of the glass fiber, metallic fiber, carbon fiber, or the like with respect to the polyamide-based resin. The reinforced resin as described above may be prepared, for example, by forming a medium by interleaving glass fiber, metallic fiber, carbon fiber, or the like, impregnating the medium with resin, and then curing the resin. The reinforced resin may also be prepared by mixing finely cut fiber pieces into liquid resin and subsequently curing the resin. Furthermore, the reinforced resin may be a lamination of a fiber-interleaved medium with layers of resin.

In the electronic device1according to the present disclosure, the protective member85is attached to the second main surface of the piezoelectric element30. The above configuration allows, when, for example, the impact caused by dropping or the like of the electronic device1brings the piezoelectric element30into contact with another member (e.g., a corner portion, an electronic member, or the like that protrudes inwardly in the housing60) disposed near the piezoelectric element30, the protective member85to mitigate the impact from the contact, thus preventing damage to the piezoelectric element30.

A surface of the protective member85that opposes to another surface of the protective member85attached to the piezoelectric element30may have a convex curved shape. When, as illustrated inFIG. 15B, the protective member85has a convex curved surface in the section taken along the line Y-Y, it is experimentally known that the protective member85tends to be better deformed in conjunction with bending and displacement of the piezoelectric element30than in cases where the protective member85has a flat plate shape and has the same thickness as the thickest portion of the convex protective member. That is to say, the protective member85with a convex curved shape is less likely to interfere with deformation of the piezoelectric element30than that with a flat plate shape, and accordingly, prevents external force from damaging the piezoelectric element30while preventing a decrease in sound pressure.

One possible way of attaching the protective member85to the piezoelectric element30is, for example, to process an organic or an inorganic synthetic resin to impart the resin with a flat surface portion to be attached to the piezoelectric element30and with a curved surface portion opposing to the flat surface portion and then, attaching the rubber to the piezoelectric element30. Alternatively, the protective member85may be formed by applying or dripping the aforementioned curable resin to the surface of the piezoelectric element30that opposes to the surface of the piezoelectric element30attached to the panel10and then, curing the resin. At room temperature, even an uncured curable resin has a certain degree of viscosity. Accordingly, when being applied or dripped onto the piezoelectric element30, the curable resin assumes a curved shape due to surface tension thereof and may be cured while maintaining the curved shape.

Although inFIGS. 15A and 15Bthe protective member85covers the second main surface of the piezoelectric element30, the present embodiment is not limited to this example, and the protective member85may also cover the second main surface of the piezoelectric element30and side surfaces extending from the second main surface. Furthermore, the protective member85may cover a surface of the piezoelectric element30other than the first main surface. The above configuration allows the protective member85to mitigate impact even to the side surfaces of the piezoelectric element30.

FIGS. 17A to 17Eillustrate the first modification of the third embodiment of the present disclosure.FIG. 17Ais a back view of the panel10to which the piezoelectric element30is attached in the electronic device1,FIGS. 17B and 17Dare sectional views of different patterns taken along a line X-X inFIG. 17A, andFIGS. 17C and 17Eare sectional views of the different patterns taken along a line Y-Y inFIG. 17A.FIG. 17Aillustrates a surface of the panel10that is visible from the side of the panel10on which the piezoelectric element30is disposed (and this also applies to the modifications below). Herein, since the piezoelectric element30is covered by the protective member85, the piezoelectric element30is not visible from the surface of the panel10that is located on the side of the piezoelectric element30. However, for better comprehension of relative arrangement of the piezoelectric element30and other members, a portion corresponding to the piezoelectric element30is indicated in white so that the piezoelectric element30becomes visible inFIG. 17A(and this also applies to the modifications below).

In the present modification, an intermediate member110is disposed between the panel10and the piezoelectric element30. The intermediate member110is attached to the panel10and the piezoelectric element30by the first joining member71(e.g., a double-sided adhesive tape) or the second joining member81(e.g., an adhesive agent including curable resin). The intermediate member110herein is, for example, the aforementioned reinforced resin.

A Flexible Printed Circuit (FPC)120is attached to a surface (the second main surface) of the piezoelectric element30that opposes to another surface (the first main surface) of the piezoelectric element30attached to the intermediate member110. The FPC25includes, for example, a film insulator (a base film) made of resin such as polyimide, a conductor layer (a signal line) formed on the base film, and an insulator covering the conductor layer except for an area corresponding to a terminal portion. The terminal portion of the FPC25and an electrode terminal portion of the piezoelectric element30are connected by adhesion using a joining material including, for example, a solder material, an anisotropic conductive material (an anisotropic conductive paste or an anisotropic conductive film) composed mainly of electrically insulating resin in which conductive particles are mixed, or the like.

The FPC25is attached to a left end portion of the second main surface of the piezoelectric element30and extends from the attaching position to be electrically connected to the controller50which is not illustrated. The FPC25conveys an electric signal applied from the controller50to the piezoelectric element30.

The protective member85is attached to the second main surface of the piezoelectric element30. Herein, since the FPC25is attached to a part of the second main surface of the piezoelectric element30as described above, the protective member85is actually disposed to cover both the piezoelectric element30and the FPC25. Accordingly, inFIG. 17A, a part of the FPC25, especially, a part of the FPC25attached to the piezoelectric element30, that is covered by the protective member85and is invisible is represented by a dotted line. Additionally, the protective member85may also be attached to a part of the second main surface of the piezoelectric element30other than the area thereof to which the FPC25is attached. The modifications described below include the similar arrangement configuration of the FPC25, and a description of the FPC25is omitted unless reference needs to be made particularly.

A surface (a surface located on an upper side in each ofFIGS. 17B, 17C, 17D, and 17E) of the protective member85that opposes to another surface of the protective member85attached to the piezoelectric element30has a convex curved shape. The protective member85with the above shape is less likely to interfere with deformation of the piezoelectric element30than that with a flat plate shape, and accordingly, prevents external force from damaging the piezoelectric element30while preventing a decrease in sound pressure.

Although inFIGS. 17A to 17Ethe protective member85covers the second main surface of the piezoelectric element30, the present modification is not limited to this example, and the protective member85may also cover the second main surface of the piezoelectric element30and side surfaces extending from the second main surface. The above configuration allows the protective member85to mitigate impact even to the side surfaces of the piezoelectric element30.

InFIGS. 17B and 17C(illustrating Pattern1), an area of a surface of the intermediate member110that is attached to the piezoelectric element30is larger than an area of the first main surface of the piezoelectric element30. The intermediate member110has the surface that is larger than the first main surface of the piezoelectric element30in the X-X direction and the Y-Y direction, and by dripping a curable resin as the protective member85to cover the larger surface, all the surfaces of the piezoelectric element30, except for the first main surface, are covered by the resin. At this time, since the intermediate member110, which has the larger surface than the first main surface of the piezoelectric element30, is disposed between the piezoelectric element30and the panel10, the dripped curable resin is less likely to adhere to the panel10.

InFIGS. 17D and 17E(illustrating Pattern2), the intermediate member110has a concave shape with an aperture surface being attached to the panel10. Space defined between the panel10and the intermediate member110is filled with, for example, a curable resin as the second joining member81(the curable resin may be injected through a through hole100provided, for example, in a part of the intermediate member110). Furthermore, as illustrated inFIG. 17E, a surface of an inner side of the intermediate member110is provided with one or more grooves. The grooves provided in the intermediate member110increase an area over which the curable resin as the second joining member81and the intermediate member110are joined, and consequently, the curable resin and the intermediate member110are joined more firmly. Additionally, a surface of the intermediate member110that is attached to the panel10or the piezoelectric element30may be provided with a groove. This allows the intermediate member110to be attached to the panel10or to the piezoelectric element30more firmly.

FIGS. 18A to 18Cillustrate the second modification of the third embodiment of the present disclosure.FIG. 18Ais a back view of the panel10to which the piezoelectric element30is attached in the electronic device1,FIG. 18Bis a sectional view taken along a line X-X inFIG. 18A, andFIG. 18Cis a sectional view taken along a line Y-Y inFIG. 18A. The piezoelectric element30is attached to the panel10by the first joining member71and the second joining member81. The electronic device1in the present modification includes a frame member95surrounding the piezoelectric element30, and the frame member95is attached to the panel10. The first main surface of the piezoelectric element30includes an edge area that is attached to the panel10by the first joining member71. The joining member71herein is, for example, a double-sided adhesive tape. The first joining member71is not attached to the entire edge area of the first main surface of the piezoelectric element30. That is to say, an area where the first joining member71is attached to the piezoelectric element30is not a closed area. For example, as illustrated inFIG. 18B, the first joining member71is not disposed in a part of a left end of the first main surface of the piezoelectric element30in the X-X direction. The part in which the first joining member is not disposed serves as a passage for a curable resin as the second joining member81which is later described.

All the areas, except for the edge area, of the first main surface of the piezoelectric element30are attached to the panel10by the second joining member81. The second joining member81is, for example, a curable resin. The curable resin may be poured into a substantially box-shaped mold defined by the panel10and an inner wall surface of the frame member95while the piezoelectric element30has been attached to the panel10by the first joining member71in advance. The curable resin thus enters space defined by the panel10and the piezoelectric element30, and then, once the curable resin is cured, the piezoelectric element30is attached to the panel10. At this time, the curable resin enters the space defined between the panel10and the piezoelectric element30through the part of the piezoelectric element30in which the first joining member is not disposed.

According to the above approach of attaching the piezoelectric element30to the panel10by the first joining member71in advance, the space defined between the piezoelectric element30and the panel10is maintained, and the curable resin may be cured while maintaining a sufficient thickness in the space. Consequently, the piezoelectric element30is attached to the panel10more firmly.

AlthoughFIG. 18Billustrates an example where the first joining member is not disposed in the part of the left end of the first main surface of the piezoelectric element30in the X-X direction, the present modification is not limited to this example. In addition to the part of the left end in the X-X direction, there may be a part of the right end that opposes the left end in which the first joining member is not disposed. With this configuration, the curable resin may enter through the passage formed in the left end in the X-X direction, and moreover, air that is present in the space defined between the panel10and the piezoelectric element30may be vented through a passage formed in the right end in the X-X direction.

The curable resin as the second joining member81may be poured substantially throughout the box-shaped inner space defined by the panel10and the inner wall surface of the frame member95. Consequently, when the inner wall surface of the frame member95is higher than the second main surface of the piezoelectric element30(the upper surface of the piezoelectric element30), the second main surface and the side surfaces of the piezoelectric element30are covered by the curable resin (i.e., substantially the entire piezoelectric element30is covered by the resin). The above configuration allows the curable resin as the second joining member81to mitigate propagation of the impact to the piezoelectric element30caused by external force, similarly to the aforementioned protective member85. Thus, the second joining member81in the present modification provides the same advantageous effect as that of the protective member85in the present disclosure. Besides, fixing the piezoelectric element30by the curable resin prevents the piezoelectric element30from being detached from the panel10in response to external impact or the like.

According to the present disclosure, since the curable resin as the second joining member81is poured into the substantially box-shaped mold defined by the panel10and the inner wall surface of the frame member95, a configuration where the piezoelectric element30attached to the panel10is covered by the resin is easily achieved.

Although in the electronic device1ofFIGS. 18A to 18Cthe piezoelectric element30is attached to the panel10by the first joining member71and the second joining member81, the electronic device1does not necessarily need to have this configuration, and the piezoelectric element30may also be attached to the panel10only by one of the first joining member71and the second joining member81. For example, the entire first main surface of the piezoelectric element30may be attached to the panel10by a double-sided adhesive tape as the first joining member71. The double-sided adhesive tape used herein is, for example, a sheet that has a three-layer structure including a polymer film whose upper and lower surfaces are each coated with an adhesive agent, that has high flexibility, and that is less likely to interfere with deformation of the piezoelectric element30and consequently, improves sound pressure characteristics. On the other hand, when a curable resin having a higher adhesive strength than the double-sided adhesive tape is used, generally, the piezoelectric element30is attached to the panel10even more firmly, and the impact to the panel10or the like is less likely to propagate to the piezoelectric element30. Accordingly, partial separation of the piezoelectric element30from the panel10is prevented. Since separation of the piezoelectric element30from the panel10is prevented, the impact to the panel10or the like is less likely to propagate to any part of the piezoelectric element30, and consequently, the piezoelectric element30is less likely to damage.

Although inFIG. 18Bthe first joining member71is not disposed in the part of the edge area on the first main surface of the piezoelectric element30, the present modification is not limited to this example, and the first joining member71may be attached to the entire edge area on the first main surface of the piezoelectric element30(i.e., the area where the first joining member71is attached may form a closed area). In this case, all the areas, except for the edge area, of the first main surface of the piezoelectric element30are not joined to the panel10by any joining member. Accordingly, in all the areas, except for the edge area, of the first main surface of the piezoelectric element30, deformation of the piezoelectric element30is not interfered with by any joining member. The above configuration improves sound pressure characteristics of the electronic device1by preventing interference in deformation of the piezoelectric element30compared with cases where the entire first main surface of the piezoelectric element30is attached to the panel10by the first joining member71or the second joining member81.

FIGS. 19A to 19Iillustrate the third modification of the third embodiment of the present disclosure.FIG. 19Ais a back view of the panel10to which the piezoelectric element30is attached in the electronic device1,FIGS. 19B, 19D, 19F, and19H are sectional views of different patterns taken along a line X-X inFIG. 19A, andFIGS. 19C, 19E, 19G, and 19Iare sectional views of the different patterns taken along a line Y-Y inFIG. 19A. The present modification differs from the aforementioned first modification in that the frame member95included in the electronic device1further includes, in addition to the wall surface portion surrounding the piezoelectric element30, a bottom surface portion extending from the wall surface portion. The bottom surface portion of the frame member95is disposed between the panel10and the piezoelectric element30and is attached to the panel10and the piezoelectric element30by the first joining member71and the second joining member81. Herein, a surface of the piezoelectric element30that is attached to the bottom surface portion of the frame member95is called the first main surface. The first main surface of the piezoelectric element30includes an edge area that is attached to the bottom surface portion of the frame member95by the first joining member71(e.g., a double-sided adhesive tape). Additionally, there may be a part of the edge area on the first main surface of the piezoelectric element30in which the first joining member71is not attached. As illustrated inFIGS. 19B and 19C(illustrating Pattern1), the bottom surface portion of the frame member95includes an edge area that is attached to the panel10by the first joining member71.

Since the frame member95has the substantially box shape defined by the wall surface portion and the bottom surface portion, the curable resin as the second joining member81may be poured into the frame member95. Accordingly, the piezoelectric element30is fixed by the resin in the frame member95, and this in turn prevents the piezoelectric element30from being detached from the bottom surface portion of the frame member95. Furthermore, after being poured into the frame member95, the curable resin also enters space defined between the piezoelectric element30and the bottom surface portion of the frame member95through a passage formed in a part of the edge area on the first main surface of the piezoelectric element30in which the first joining member71is not disposed, thereby fixing the piezoelectric element30to the frame member95.

The bottom surface portion of the frame member95may be provided, in a part thereof, with a through hole. For example, as illustrated inFIGS. 19B and 19D, the through hole may be provided in the vicinity of a left end of the bottom surface portion of the frame member95in the X-X direction. Providing the through hole allows the curable resin, which has been poured into the frame member95, to enter space defined between the bottom surface portion of the frame member95and the panel10through the through hole. Once the curable resin is cured, the frame member95is attached to the panel10. As described above, inFIGS. 19B and 19C(illustrating Pattern1), the edge area of the bottom surface portion of the frame member95is attached to the panel10by the first joining member71, and therefore, the space is defined between the bottom surface portion and the panel10to let the curable resin to make an entrance.

Additionally, there may be a part of the edge area of the bottom surface portion of the frame member95in which the first joining member71is not attached. Such a part of the frame member95may serve as a passage for venting, when the curable resin enters the space defined between the bottom surface portion and the panel10through a through hole provided, for example, in the bottom surface portion of the frame member95, air that is present in the space. When the passage for venting air is formed in the vicinity of an end portion (a right end in the X-X direction) of the bottom surface portion of the frame member95that opposes to another end portion of the bottom surface portion of the frame member95provided with the through hole as illustrated inFIG. 19B, the entered curable resin is less likely to leak to the outside through the passage.

It is not necessarily requisite that the edge area of the bottom surface portion of the frame member95be attached to the panel10by the first joining member71. For example, space through which the second joining member81enters may be formed between the panel10and the bottom surface portion of the frame member95by shaping the panel10into a concave shape as illustrated inFIGS. 19D and 19E(illustrating Pattern2).

Although inFIGS. 19B and 19C(illustrating Pattern1) andFIGS. 19D and 19E(illustrating Pattern2) the bottom surface portion of the frame member95is provided, in a part thereof, with the through hole, the through hole may be omitted.FIGS. 19F and 19G(illustrating Pattern3) andFIGS. 19H and 19I(illustrating Pattern4) illustrate examples where no through hole is provided in the bottom surface portion of the frame member95. InFIGS. 19F and 19G(illustrating Pattern3), the edge area of the bottom surface portion of the frame member95is attached to the panel10by the first joining member71, and the panel10is provided with a through hole100within an area of the panel10over which the bottom surface portion of the frame member95is attached. By pouring the curable resin through the through hole100provided in the panel10, the space defined between the panel10and the bottom surface portion of the frame member95is filled with the curable resin. Consequently, the frame member95and the panel10are attached by the resin.

It is not necessarily requisite that the edge area of the bottom surface portion of the frame member95be attached to the panel10by the first joining member71. For example, space through which the second joining member81enters may be formed between the panel10and the bottom surface portion of the frame member95by shaping the panel10into a concave shape as illustrated inFIGS. 19H and 19I(illustrating Pattern4).

In the configurations ofFIGS. 19F and 19G(illustrating Pattern3) andFIGS. 19H and 19I(illustrating Pattern4), a bezel may also be provided to cover the through hole100provided in the panel10. The bezel may extend from a part of the housing60that forms a side surface of the electronic device1. The bezel covers the through hole100provided in the panel10to make the through hole100unexposed to the outside of the electronic device1, and accordingly, the appearance is not spoiled.

The bottom surface portion of the frame member95is attached to the panel10and the piezoelectric element30and is disposed between the panel10and the piezoelectric element30. Herein, when, for example, the frame member95is made of iron, stainless, aluminum, or the like, the bottom surface portion of the frame member95also serves as a reinforcing plate that prevents, when external force is applied to the panel10, propagation of the external force to the piezoelectric element30, thus preventing damage to the piezoelectric element30.

Although in the above configurations the piezoelectric element30is attached to the bottom surface portion of the frame member95, the present modification is not limited to these examples, and the piezoelectric element30may be attached to the wall surface portion of the frame member95.

Meanwhile, in some cases in assembly of members constituting the electronic device1during manufacturing of the electronic device1according to the present disclosure, a unit or the like including a predetermined combination of independent members or sets of members may be transported. In these cases, when a unit includes the protective member85attached to a predetermined surface of the piezoelectric element30as described above, damage due to external impact or the like is prevented during transportation. At this time, when at least a part of the piezoelectric element30is covered by a curable resin, external impact may be mitigated by the curable resin during transportation. Needless to say, when a surface of the piezoelectric element30other than the predetermined surface attached with the protective member85is attached to a predetermined plate-shaped member, the unit is capable of deforming the plate-shaped member due to deformation of the piezoelectric element30to thereby transmit human-body vibration sound to an object that is in contact with the plate-shaped member.

A surface of the protective member85that opposes to another surface of the protective member85attached to the piezoelectric element30may have a convex curved shape. Such a protective member85is less likely to interfere with deformation of the piezoelectric element30than that with a flat plate shape.

Furthermore, when a unit including the piezoelectric element30fixed in the frame member95in advance is formed by attaching the piezoelectric element30to a bottom portion of an inner side of the frame member (hereinafter, may be called “the box-shaped member”) including the wall surface portion and the bottom surface portion as described above and by pouring a curable resin into the box-shaped member, damage due to external impact or the like is prevented during transportation. In this case, when a surface of the bottom portion of the box-shaped member that opposes to another surface of the bottom portion of the box-shaped member attached with the piezoelectric element30is attached to a predetermined plate-shaped member, the plate-shaped member is deformed due to deformation of the piezoelectric element30, and human-body vibration sound is transmitted to an object that is in contact with the plate-shaped member.

The piezoelectric element30included in the above unit does not necessarily need to be attached to a box-shaped member. For example, the unit may include the piezoelectric element30attached to a predetermined plate-shaped member (the first plate-shaped member) and also include a predetermined protective member attached to a surface (the second main surface) of the piezoelectric element30that opposes to another surface (the first main surface) of the piezoelectric element30that is attached to the first plate-shaped member. The predetermined protective member includes, for example, an elastic member, a curable resin, or the like as described above, and the protective member mitigates external impact by covering the second main surface of the piezoelectric element30.

FIGS. 20A to 20Eillustrate the fourth modification of the third embodiment of the present disclosure.FIG. 20Ais a back view of the panel10to which the piezoelectric element30is attached in the electronic device1,FIGS. 20B and 20Dare sectional views of different patterns taken along a line X-X inFIG. 20A, andFIGS. 20C and 20Eare sectional views of the different patterns taken along a line Y-Y inFIG. 20A. In the present modification, the frame member95includes the bottom surface portion, the first wall surface portion standing from a surface of the bottom surface portion that is attached with the piezoelectric element30, and the second wall surface portion standing from another surface of the bottom surface portion that opposes to the surface of the bottom surface portion attached with the piezoelectric element30. With the second wall surface portion, the frame member95defines space between the panel10and the bottom surface portion of the frame member95when the second wall portion is attached to the panel10, and a curable resin or the like as the second joining member81may be filled into the defined space. Accordingly, in the present modification, the space between the bottom surface portion and the panel10is defined easily without the need for disposing the first joining member71between the bottom surface portion of the frame member95and the panel10or for forming a part of the panel10into a concave shape. Additionally, as illustrated inFIGS. 20A to 20E, the first wall surface portion and the second wall surface portion standing from the bottom surface portion of the frame member95may be flush with each other, i.e., may be integrated to form a side surface of the frame member95.

In the configuration ofFIGS. 20B and 20C(illustrating Pattern1), the bottom surface portion of the frame member95is provided in a part thereof with a through hole through which the curable resin poured into the frame member95enters the space defined between the panel10and the bottom surface portion of the frame member95. In the configuration inFIGS. 20D and 20E(illustrating Pattern2), the panel10is provided with a through hole100through which the curable resin is poured to be filled into the space defined between the panel10and the bottom surface portion of the frame member95. The through hole100provided in the panel10is covered by, for example, a bezel extending from the housing60.

FIGS. 21A to 21Eillustrate the fifth modification of the third embodiment of the present disclosure.FIG. 21Ais a back view of the panel10to which the piezoelectric element30is attached in the electronic device1,FIGS. 21B and 21Dare sectional views of different patterns taken along a line X-X inFIG. 21A, andFIGS. 21C and 21Eare sectional views of the different patterns taken along a line Y-Y inFIG. 21A. The electronic device1of the present modification includes a cover member91that is attached to the panel10. The cover member91includes a wall surface portion surrounding the piezoelectric element30and a top surface portion extending from the wall surface portion.

As illustrated inFIGS. 21A to 21E, the piezoelectric element30is disposed in space defined by the panel10and the cover member91. Thus, the cover member91protects the piezoelectric element30against external impact.

In the present modification, the space defined by the cover member91and the panel10may be filled with a curable resin or the like as the second joining member81. The above configuration fixes the piezoelectric element30by the curable resin and prevents the piezoelectric element30from being detached from the panel10in response to external impact. In the configuration ofFIGS. 21B and 21C(illustrating Pattern1), the cover member91is provided in a part thereof with the through hole100through which the curable resin is poured to be filled into the space defined in the cover member91. In the configuration inFIGS. 21D and 21E(illustrating Pattern2), the panel10is provided with the through hole100through which the curable resin is poured to be filled into the space defined in the cover member91.

In the present modification, as illustrated inFIGS. 21B and 21C(illustrating Pattern1), the FPC25extends from a part of the piezoelectric element30where the FPC25is attached to the outside of the cover member91through the through hole100. However, the present modification is not limited to this example, and as illustrated inFIGS. 21D and 21E(illustrating Pattern2), additional hole may be provided in the cover member91, and the FPC25may extend through the additional hole.

Fourth Embodiment

FIGS. 22A and 22Billustrate a configuration of the electronic device1according to the fourth embodiment of the present disclosure.FIG. 22Ais a front view, andFIG. 22Bis a sectional view taken along a line Y-Y inFIG. 22A. The electronic device1illustrated inFIGS. 22A and 22Bis a smartphone in which a touch panel, i.e., a glass plate, is mounted as the panel10on the front surface of the housing60(e.g., a metal or a resin casing). The panel10is joined to the housing60by the joining member70, and thus, attached to the housing60. The joining member70used to attach the panel10to the housing60is, for example, an adhesive agent or a double-sided adhesive tape. The display20is adhered and attached to the panel10by the joining member70. Examples of the joining member70that may be preferably used to attach the display20to the panel10include an optical elastic resin, which is a colorless and transparent ultraviolet-curable acrylic adhesive agent. The piezoelectric element30is joined to the panel10by way of the intermediate member110. The piezoelectric element30is attached to the intermediate member110by the joining member70, and the intermediate member110is attached to the panel10by the joining member70. A description is given later in detail of how the intermediate member110, the panel10, and the piezoelectric element30are attached. The input unit40is attached to the housing60, similarly to the panel10. The panel10, the display20, and the piezoelectric element30each have a substantially rectangular shape.

The display20is disposed in substantially the middle of the panel10in the short-side direction thereof. The piezoelectric element30is disposed near the end portion of the panel10in the longitudinal direction of the panel10at a predetermined distance from the end portion in a manner such that the longitudinal direction of the piezoelectric element30extends along the short side of the panel10. The display20and the piezoelectric element30are disposed side by side in the direction parallel to the surface of the inner side of the panel10.

According to the electronic device1of the present embodiment with the above configuration, the panel10is deformed due to deformation of the piezoelectric element30attached to the back surface of the panel10, and air conduction sound and vibration sound are transmitted to an object that is in contact with the deformed panel10.

FIG. 23illustrates one example of the vibration of the panel10of the electronic device1according to the fourth embodiment. As illustrated in the figure, in the electronic device1according to the present embodiment, the piezoelectric element30is attached to the upper portion of the panel10, and the display20is attached to the lower portion of the panel10relative to the upper portion. The panel10is bent by the piezoelectric element30in a manner such that a portion of the panel10directly above the piezoelectric element30protrudes relative to neighboring portions of the panel10in the long-side direction2aof the panel10. On the other hand, the lower portion of the panel10that is attached with the display20is less likely to vibrate compared to the upper portion of the panel10that is attached with the piezoelectric element30. As a result, the lower portion of the panel10provides less sound leakage due to the vibration occurring in the lower portion of the panel10.

The electronic device1transmits sound by the vibration of the panel10. In this regard, compared with cases where the piezoelectric element30is attached to the housing60to vibrate the housing60, the user might drop the electronic device due to the vibration of the housing60during voice communication when the user holds the electronic device in the hand (since during voice communication the user usually holds the housing portion of the electronic device). In contrast, the electronic device1, which vibrates the panel10, hardly poses such a problem. Of course, however, the piezoelectric element30may also be attached to the housing60when the piezoelectric element30does not vibrate greatly.

FIGS. 24A to 24Eillustrate a configuration of the electronic device1according to the fourth embodiment of the present disclosure in detail.FIG. 24Ais a back view of the panel10to which the piezoelectric element30is attached in the electronic device1,FIGS. 24B and 24Dare sectional views of different patterns taken along a line X-X inFIG. 24A, andFIGS. 24C and 24Eare sectional views of the different patterns taken along a line Y-Y inFIG. 24A.FIG. 24Aillustrates a surface of the panel10that is visible from the side of the panel10on which the piezoelectric element30is disposed (and this also applies to the modifications below). As illustrated inFIGS. 24A to 24E, the piezoelectric element30is attached to the panel10by way of the intermediate member110.

The Flexible Printed Circuit (FPC)120is attached to a surface (the second main surface) of the piezoelectric element30that opposes to another surface (the first main surface) of the piezoelectric element30that is attached to the intermediate member110. The FPC25includes, for example, a film insulator (a base film) made of resin such as polyimide, a conductor layer (a signal line) formed on the base film, and an insulator covering the conductor layer except for an area corresponding to a terminal portion. The terminal portion of the FPC25and an electrode terminal portion of the piezoelectric element30are connected by adhesion using a joining material including, for example, a solder material, an anisotropic conductive material (an anisotropic conductive paste or an anisotropic conductive film) composed mainly of electrically insulating resin in which conductive particles are mixed, or the like.

The FPC25is attached to the left end portion of the second main surface of the piezoelectric element30and extends from the attaching position to be electrically connected to the controller50which is not illustrated. The FPC25conveys an electric signal applied from the controller50to the piezoelectric element30The modifications described below include the similar arrangement configuration of the FPC25, and a description of the FPC25is omitted unless reference needs to be made particularly.

The intermediate member110is, for example, a member that prevents external force from being conveyed to the piezoelectric element30to reduce damage to the piezoelectric element caused by the external force. Such a member may be formed by, for example, an elastic material of organic synthetic rubber, a representative of which includes polybutadiene-based, nitrile-based, and chloroprene-based synthetic rubber, and inorganic synthetic rubber, such as silicone. The member may also be formed by a curable resin having thermosetting properties, thermoplasticity, moisture curable properties, ultraviolet-curable properties, or the like.

Furthermore, the intermediate member110is, for example, a member that prevents excessive deformation of the piezoelectric element30. Such a member may be formed by, for example, a copper sheet, an iron sheet, or a phosphor bronze sheet. The member may also be formed by, for example, a stainless sheet or a metallic sheet made of aluminum having a certain degree of elasticity. The thickness of the metallic sheet, such as a stainless sheet, may be in the range from 0.2 mm to 0.8 mm and determined appropriately depending on a voltage value or the like applied to the piezoelectric element30. Additionally, the member may also be formed by a plurality of metals, such as a metallic sheet including a copper sheet plated with silver, or a laminated sheet including a copper sheet and an aluminum sheet.

The intermediate member110may also include a composite of an organic material and an inorganic material (or metal). One example is a composite member (reinforced resin) obtained by mixing glass fiber, metallic fiber, carbon fiber, or the like into a polyimide-based resin as the base material. The strength, rigidity, and elasticity of the composite member may be controlled appropriately in accordance with the content of the glass fiber, metallic fiber, carbon fiber, or the like with respect to the polyamide-based resin. The reinforced resin as described above may be prepared, for example, by forming a medium by interleaving glass fiber, metallic fiber, carbon fiber, or the like, impregnating the medium with resin, and then curing the resin. The reinforced resin may also be prepared by mixing finely cut fiber pieces into liquid resin and subsequently curing the resin. Furthermore, the reinforced resin may be a lamination of a fiber-interleaved medium with layers of resin.

As described above, the piezoelectric element30is attached to the intermediate member110by the joining member70, and the intermediate member110is attached to the panel10by the joining member70. Herein, the joining member70includes a combination of different joining members (i.e., the first joining member71and the second joining member81). In the present disclosure, the second joining member81is more flexible than the first joining member71. For example, the first joining member71is the aforementioned curable resin (e.g., epoxy resin as a thermosetting resin), and the second joining member81is a double-sided adhesive tape including an acryl or a Polyethylene terephthalate (PET) base coated with an adhesive agent. The acryl or the Polyethylene terephthalate (PET) base has a film shape, a nonwoven fabric film shape, a cellular porous shape, or the like, and therefore, a double-sided adhesive tape with the base is more flexible than cured resin. Accordingly, compared with the first joining member71, the second joining member81is more likely to be deformed in conjunction with deformation of other members joined with the joining member or more likely to mitigate propagation of external force to the other members.

The piezoelectric element30may be attached to the intermediate member110by using the first joining member71or the second joining member81. InFIGS. 24A to 24E, the piezoelectric element30is attached to the intermediate member110by the second joining member81. In the illustrated examples, flexibility of the second joining member81does not interfere with displacement of the piezoelectric element30, and consequently, sound pressure characteristics are improved. When the first joining member71is used instead of the second joining member81, the piezoelectric element30is attached to the intermediate member110more firmly, and separation of the piezoelectric element30from the intermediate member110is prevented.

In the electronic device1according to the present disclosure, in a predetermined area of the intermediate member110that includes at least an area located right below the piezoelectric element30in a direction in which the panel10, the intermediate member110, and the piezoelectric element30are laminated, the intermediate member110is attached to the panel10by the first joining member71, and in at least a part of a periphery of the predetermined area, the intermediate member110is attached to the panel10by the second joining member81.

Since the intermediate member110is attached to the panel10firmly by the first joining member in the predetermined area including at least the area located right below the piezoelectric element30in the direction in which the panel10, the intermediate member110, and the piezoelectric element30are laminated, external impact to the panel10caused by dropping or the like of the electronic device1is less likely to be propagated to the piezoelectric element30, and consequently, the piezoelectric element30is protected from a crack or the like.

Furthermore, since the intermediate member110is attached to the panel10by the second joining member81that is more flexible than the first joining member71in a part of the periphery of the first joining member71, the second joining member81mitigates impact propagating from a periphery of an area of the panel10where the intermediate member110is attached to the attached area of the panel10along the main surface of the panel10, and consequently, the piezoelectric element30is protected from a crack or the like.

Although inFIGS. 24A to 24Ea double-sided adhesive tape as the second joining member81is disposed over the entire marginal area of the area of the panel10where the intermediate member110is attached, the present embodiment is not necessarily limited to this configuration. For example, when the intermediate member110(or the piezoelectric element30) is attached to an end portion on the upper side of the panel10, impact is likely to propagate from an area of the panel10that is located on the lower side of the area where the intermediate member110is attached, and therefore, the double-sided adhesive tape may be disposed only on the lower side (i.e., on a side of the panel10that opposes to the end portion on the upper side) of the panel10in the attached area. The above configuration allows the second joining member81to efficiently mitigate impact propagating along the main surface of the panel10.

According to the electronic device1of the present disclosure with the above configuration, a marginal area of a surface (the first main surface) of the intermediate member110that is attached to the panel10is attached to the panel10by a double-sided adhesive tape as the second joining member81. Accordingly, the marginal area of the first main surface of the intermediate member110may be attached to the panel10by using the double-sided adhesive tape in advance to define space between the panel10, the intermediate member110, and the double-sided adhesive tape before a curable resin as the first joining member71is disposed, and then, the curable resin as the second joining member81may be filled into the space. That is to say, by disposing the double-sided adhesive tape between the panel10and the intermediate member110, a passage for the curable resin is formed. By attaching the intermediate member110to the panel10by the second joining member81in advance, the space defined between the panel10and the intermediate member110is maintained, and the curable resin may be cured while maintaining a sufficient thickness in the space. Consequently, the intermediate member110is attached to the panel10more firmly. As illustrated inFIG. 24B(illustrating Pattern1), the intermediate member110is provided in a part thereof with the through hole100. Alternatively, as illustrated inFIG. 24D(illustrating Pattern2), the panel10is provided in a part thereof with the through hole100. The curable resin as the second joining member81may be filled through the through hole100. The through hole100is the first hole through which the space defined between the panel10, the intermediate member110, and the double-sided adhesive tape communicates with the outside of the space. In the configuration ofFIGS. 24D and 24E(illustrating Pattern2), a bezel may also be provided to cover the through hole100provided in the panel10. The bezel may extend from a part of the housing60that forms a side surface of the electronic device1. The bezel covers the through hole100provided in the panel10to make the through hole100unexposed to the outside of the electronic device1, and thus, the appearance is not spoiled.

The intermediate member110or the panel10may be further provided with the second hole that is different from the first hole, namely, the through hole100. This configuration allows an adhesive agent to be filled into the space defined between the panel10and the intermediate member110through the first hole and also allows air that is present in the space to be vented to the outside through the second hole.

Although in the above configurations the first and the second hole are provided in the intermediate member110or the panel10, the present embodiment is not limited to these examples, and at least one of the first and the second hole may be provided by forming a partial cut-out in the double-sided adhesive tape by which the intermediate member110is attached to the panel10.

When the intermediate member110has a substantially rectangular shape as illustrated inFIGS. 24A to 24E, the double-sided adhesive tape as the second joining member81may be disposed in both edge portions of the first main surface of the intermediate member110along the longitudinal direction, not in both end portions along the short-side direction. By doing so, substantially rectangular space may be defined between the panel10and the intermediate member110, with the first hole being provided in one end of the space in the longitudinal direction, and with the second hole being provided in another end of the space in the longitudinal direction.

FIGS. 25A to 25Eillustrate the first modification of the fourth embodiment of the present disclosure.FIG. 25Ais a back view of the panel10to which the intermediate member110and the piezoelectric element30are attached in the electronic device1,FIGS. 25B and 25Dare sectional views of different patterns taken along a line X-X inFIG. 25A, andFIGS. 25C and 25Eare sectional views of the different patterns taken along a line Y-Y inFIG. 25A. In the present modification, a curable resin as the protective member85is applied to a surface (the second main surface) of the piezoelectric element30that opposes to another surface (the first main surface) of the piezoelectric element30attached to the intermediate member110. Since the piezoelectric element30is covered by the protective member85, the piezoelectric element30ought to be invisible from the surface of the panel10that is located on the side of the piezoelectric element30inFIG. 25A. However, for better comprehension of relative arrangement of the piezoelectric element30and other members, a portion corresponding to the piezoelectric element30is indicated in white so that the piezoelectric element30becomes visible inFIG. 24A(and this also applies to the modifications below). Furthermore, since the FPC25is attached to a part of the second main surface of the piezoelectric element30as described above, the protective member85is actually disposed to cover both the piezoelectric element30and the FPC25. Accordingly, inFIG. 25A, a part of the FPC25that is covered by the protective member85and is invisible is represented by a dotted line. Additionally, the protective member85may also be attached to a part of the second main surface of the piezoelectric element30other than the area thereof to which the FPC25is attached (and this also applies to the modifications below).

In the electronic device1according to the present disclosure, the protective member85is attached to the second main surface of the piezoelectric element30. The above configuration allows, when, for example, the impact caused by dropping or the like of the electronic device1brings the piezoelectric element30into contact with another member (e.g., a corner portion, an electronic member, or the like that protrudes inwardly in the housing60) disposed near the piezoelectric element30, the protective member85to mitigate the impact from the contact, thus preventing damage to the piezoelectric element30.

A surface of the protective member85that opposes to another surface of the protective member85attached to the piezoelectric element30may have a convex curved shape. When, as illustrated inFIG. 25B, the protective member85has a convex curved surface in the section taken along the line Y-Y, it is experimentally known that the protective member85tends to be better deformed in conjunction with bending and displacement of the piezoelectric element30than in cases where the protective member85has a flat plate shape and has the same thickness as the thickest portion of the convex protective member. That is to say, the protective member85in a convex curved shape is less likely to interfere with deformation of the piezoelectric element30than that in a flat plate shape, and accordingly, prevents external force from damaging the piezoelectric element30while preventing a decrease in sound pressure.

One possible method of attaching the protective member85to the piezoelectric element30includes processing, for example, organic or inorganic synthetic resin to impart the resin with a flat surface portion to be attached to the piezoelectric element30and with a curved surface portion opposing to the flat surface portion and then, attaching the rubber to the piezoelectric element30. Alternatively, the protective member85may be formed by applying or dripping the aforementioned curable resin to the surface of the piezoelectric element30that opposes to the surface of the piezoelectric element30attached to the panel10and then, curing the resin. At room temperature, even an uncured curable resin has a certain degree of viscosity. Accordingly, when being applied or dripped onto the piezoelectric element30, the curable resin assumes a curved shape due to surface tension thereof and may be cured while maintaining the curved shape.

Although the protective member85, which covers the second main surface of the piezoelectric element30, is capable of preventing damage to the piezoelectric element30, the present modification is not limited to this example, and the protective member85may also cover the second main surface of the piezoelectric element30and side surfaces extending from the second main surface. The above configuration allows the protective member85to mitigate impact even to the side surfaces of the piezoelectric element30.

When the protective member85is made of a curable resin that is the same as a curable resin used as the panel10and the first joining member71, the protective member85and the first joining member71may be integrally formed. That is to say, as illustrated inFIGS. 25B and 25D, the protective member85may be formed by filling the curable resin into the space defined between the panel10and the intermediate member110through the through hole100provided in the intermediate member110and subsequently, dripping the curable resin to cover an upper surface of the intermediate member110and the upper surface (the second main surface) of the piezoelectric element30, and then, curing the resin. The above process simplifies operation compared with cases where the first joining member71and the protective member85are formed separately.

InFIGS. 25A to 25E, an area of a surface of the intermediate member110that is attached to the piezoelectric element30is larger than an area of the first main surface of the piezoelectric element30. The intermediate member110has the surface that is larger than the first main surface of the piezoelectric element30in the X-X direction and the Y-Y direction, and dripping the curable resin as the protective member85to cover the larger surface allows all the surfaces, except for the first main surface, of the piezoelectric element30to be covered by the resin. At this time, since the intermediate member110, which has the larger surface than the first main surface of the piezoelectric element30, is disposed between the piezoelectric element30and the panel10, the dripped curable resin is less likely to adhere to the panel10.

InFIGS. 25D and 25E(illustrating Pattern2), the surface (the first main surface) of the intermediate member110that is attached to the panel10is provided with one or more grooves as illustrated inFIG. 25E. The grooves provided in the intermediate member110increase an area over which the curable resin as the first joining member71and the intermediate member110are joined, and consequently, the curable resin and the intermediate member110are joined more firmly. Additionally, a surface of the intermediate member110that is attached to the panel10or the piezoelectric element30may be provided with a groove. With this configuration, the intermediate member110is attached to the panel10or to the piezoelectric element30more firmly.

FIGS. 26A to 26Cillustrate the second modification of the fourth embodiment of the present disclosure.FIG. 26Ais a back view of the panel10to which the intermediate member110and the piezoelectric element30are attached in the electronic device1,FIG. 26Bis a sectional view taken along a line X-X inFIG. 26A, andFIG. 26Cis a sectional view taken along a line Y-Y inFIG. 26A. In the present modification, the intermediate member110includes a bottom surface portion to which the piezoelectric element30is attached and a wall surface portion standing from the bottom surface portion.

A curable resin as the protective member85may be poured into box-shaped inner space defined by the bottom surface portion and the wall surface portion of the intermediate member110. Consequently, when an inner wall surface of the intermediate member110is higher than the second main surface of the piezoelectric element30(the upper surface of the piezoelectric element30), the second main surface and the side surfaces of the piezoelectric element30are covered by the curable resin. (That is to say, substantially the entire piezoelectric element30is covered by the resin.) Accordingly, the curable resin as the protective member85further mitigates propagation of the impact to the piezoelectric element30caused by external force. Besides, fixing the piezoelectric element30by the curable resin prevents the piezoelectric element30from being detached from the intermediate member110in response to external impact or the like.

According to the present modification, since the intermediate member110has the substantially box shape including the bottom surface portion and the wall surface portion, a configuration where the piezoelectric element30is covered by the curable resin is easily achieved by pouring the resin into the box-shaped member.

The piezoelectric element30is attached to the intermediate member110by the first joining member71and the second joining member81. The first main surface of the piezoelectric element30includes an edge area that is attached to intermediate member110by the second joining member81(e.g., a double-sided adhesive tape). The second joining member81is not attached to the entire edge area of the first main surface of the piezoelectric element30. For example, as described earlier, a partial cut-out may be formed in the double-sided adhesive tape by which the intermediate member110is attached with the piezoelectric element30. InFIG. 26B, the second joining member81(the double-sided adhesive tape) is not disposed (i.e., the cut-out is formed) in a part of the left end of the first main surface of the piezoelectric element30in the X-X direction. The part of the left end in which the second joining member81is not disposed serves as a passage for a curable resin as the first joining member71.

The curable resin as the first joining member71may be poured into the substantially box-shaped space in the intermediate member110while the piezoelectric element30has been attached to the intermediate member110by the second joining member81in advance. This allows the curable resin to enter the space defined between the piezoelectric element30and the intermediate member110while the space is maintained, and the curable resin may be cured while maintaining a sufficient thickness. Consequently, the piezoelectric element30is attached to the intermediate member110more firmly.

Although in the electronic device1ofFIGS. 26A to 26Cthe piezoelectric element30is attached to the intermediate member110by the first joining member71and the second joining member81, the electronic device1does not necessarily need to have this configuration, and the piezoelectric element30may also be attached to the intermediate member110only by one of the first joining member71and the second joining member81. For example, the entire first main surface of the piezoelectric element30may be attached to the intermediate member110by a double-sided adhesive tape as the second joining member81.

Although inFIG. 26Bthe second joining member81is not disposed in the part of the edge area on the first main surface of the piezoelectric element30, the present modification is not limited to this example, and the second joining member81may also be attached to the entire edge area on the first main surface of the piezoelectric element30(i.e., the area where the second joining member81is attached may form a closed area). In this case, all the areas, except for the edge area, of the first main surface of the piezoelectric element30are not joined to the panel10by any joining member. Accordingly, in all the areas, except for the edge area, of the first main surface of the piezoelectric element30, deformation of the piezoelectric element30is not interfered with by any joining member. The above configuration improves sound pressure characteristics of the electronic device1by preventing interference in deformation of the piezoelectric element30compared with cases where the entire first main surface of the piezoelectric element30is attached to the panel10by the first joining member71or the second joining member81.

In the present modification also, the intermediate member110may be provided in a part (e.g., the bottom surface portion) thereof with the through hole100. Providing the through hole100allows the curable resin, which has been poured into the inner space of the intermediate member110, to enter space defined between the intermediate member110and the panel10through the through hole. Once the curable resin is cured, the intermediate member110is attached to the panel10.

Meanwhile, in some cases in assembly of members constituting the electronic device1during manufacturing of the electronic device1according to the present disclosure, a unit or the like including a predetermined combination of independent members or sets of members may be transported. Such a unit may include the piezoelectric element30attached to a predetermined plate-shaped member (the first plate-shaped member). Furthermore, in a predetermined area of the unit that includes at least an area located right below the piezoelectric element30in a direction in which the piezoelectric element30and the first plate-shaped member are laminated, such a unit may be attached to the first plate-shaped member by the first joining member (e.g., a curable resin), and in at least a part of a periphery of the predetermined area, such a unit may be attached to the first plate-shaped member by the second joining member (e.g., an adhesive agent) that is more flexible than the first joining member. This configuration allows the second joining member to mitigate external impact applied to the first plate-shaped member and propagated to the piezoelectric element30along the first plate-shaped member during transportation. Needless to say, when a surface of the first plate-shaped member other that opposes to another surface of the first plate-shaped member attached with the piezoelectric element30is attached to a predetermined plate-shaped member (the second plate-shaped member) that is different from the first plate-shaped member, the unit is capable of deforming the second plate-shaped member due to deformation of the piezoelectric element30to thereby transmit human-body vibration sound to an object that is in contact with the second plate-shaped member.

Such a unit may also include the protective member85attached to a surface of the piezoelectric element30that opposes to another surface of the piezoelectric element30attached to the panel10. A surface of the protective member85that opposes to another surface of the protective member85attached to the piezoelectric element30may have a convex curved shape.

The piezoelectric element30included in the above unit does not necessarily need to be attached to a plate-shaped member. For example, the piezoelectric element30may be attached to a bottom surface of a predetermined box-shaped member. In this case, by forming a unit including the piezoelectric element30fixed in the box-shaped member in advance by pouring a curable resin into the box-shaped member, damage due to external impact or the like is further prevented during transportation. At this time, when at least a part of the piezoelectric element30is covered by the curable resin, external impact is mitigated by the curable resin during transportation.

In the above description of the configuration of the electronic device1according to the present disclosure, space to be filled with a curable resin as the first joining member71is formed with the second joining member81interposed between a flat surface portion of the intermediate member110and the panel10. However, the way of forming the space is not limited to this example.

FIGS. 27A to 27Cillustrate the third modification of the fourth embodiment of the present disclosure.FIG. 27Ais a back view of the panel10to which the intermediate member110and the piezoelectric element30are attached in the electronic device1,FIG. 27Bis a sectional view taken along a line X-X inFIG. 27A, andFIG. 27Cis a sectional view taken along a line Y-Y inFIG. 27A. As illustrated inFIGS. 27A to 27C, the intermediate member110having a concave shape is used, and an aperture surface of the intermediate member110is attached to the panel10by the second joining member81. The above configuration provides a larger space to be filled with a curable resin as the first joining member71compared with cases where the flat surface portion of the intermediate member110is attached to the panel10.

Although the present disclosure has been described based on the drawings and the embodiments thereof, it is to be noted that a person skilled in the art may easily make various changes and modifications according to the present disclosure. Therefore, such changes and modifications are to be understood as included within the scope of the present disclosure. For example, functions and so forth included in the members, steps, or the like may be rearranged as long as the functions and the like are logically consistent. A plurality of component parts, the steps, and the like may also be integrated or separated.

For example, as illustrated inFIG. 28, the panel10may be configured to be joined to the housing60by the joining member70. Thus preventing direct propagation of the vibration of the panel10to the housing60makes it less likely that the user will drop the electronic device1compared with cases where the housing itself undergoes a large vibration. The joining member70may also be an adhesive agent that is not thermosetting. This provides an advantage that contraction due to a thermal stress is less likely to occur between the housing60and the panel10during curing. The joining member70may also be a double-sided adhesive tape. This provides an advantage that a contraction stress, which often occurs when an adhesive agent is used, is less likely to be generated between the housing60and the panel10.

When the panel10and the display unit20are not superposed, for example, the piezoelectric element30may be disposed in the middle of the panel10. When the piezoelectric element30is disposed in the middle of the panel10, the vibration of the piezoelectric element30is evenly transmitted to the whole panel10, thereby improving a quality of air conduction sound and allowing the user to perceive human-body vibration sound even when the user places the ear in contact with the panel10at different positions of the panel10. Note that, similarly to the above embodiments, the piezoelectric element30may be provided in plurality.

Although in the above electronic device1the piezoelectric element30is adhered to the panel10, the piezoelectric element30may be attached to another place than the panel10. For example, the piezoelectric element30may be adhered to a battery lid that is configured to be attached to the housing60to cover a battery. Since the battery lid is often attached to a surface different from the panel10in the electronic device1such as the mobile phone, the above configuration enables the user to listen to sound by placing a part of the body (e.g., the ear) in contact with the surface different from the panel10.

The panel10may form a part or an entirety of any one of a display panel, an operation panel, a cover panel, and a lid panel that allows a rechargeable battery to be detachable. Preferably, when the panel10is a display panel, the piezoelectric element30is disposed outside of a display area provided for display function. The above structure provides an advantage that display is less likely to be disturbed by the piezoelectric element30. The operation panel includes the touch panel of the first embodiment. The operation panel may also include a sheet key, namely, a member of the foldable mobile phone or the like that is integrally provided with a key top as the operation key and that forms one surface of the housing on an operational side.

Meanwhile, in the first and the second embodiment, the joining member used for adhering the panel10with the piezoelectric element30, the joining member used for adhering the panel10to the housing60, and the like are denoted by the same reference numeral as the joining member70. However, the joining member used in the first and the second embodiment may be varied appropriately depending on the members to be joined.

Furthermore, although a double-sided adhesive tape or an adhesive agent is described as an example of the joining member70used to joining the panel10to the housing60, a double-sided adhesive tape and an adhesive agent may be used not alone but together. In this case, a double-sided adhesive tape may be applied to the housing60, and an adhesive agent having a higher adhesive strength than the double-sided adhesive tape may be applied over the double-sided adhesive tape, to join the panel10to the housing60. The double-sided adhesive tape and the adhesive agent are adhered to each other firmly, and consequently, the panel10and the housing60are joined firmly. Furthermore, an adhesive agent does not need to be applied over a double-sided adhesive tape and may be partially cut out, and an adhesive agent may be filled into space obtained by the cut-out to join the panel10and the housing60. The adhesive agent used herein may be an adhesive agent that is not thermosetting or a moisture curable elastic adhesive agent that reacts with water (moisture) and is moisture-cured. A moisture curable elastic adhesive agent may be mainly composed of a silyl group-containing special polymer.

In the above description, the electronic device1according to the present disclosure includes the panel10attached with the piezoelectric element30, and sound is generated due to displacement of the piezoelectric element30. However, sound may be generated by a member other than the panel10. Any member that constitutes the electronic device1and that has a substantially flat plate shape in part may generate sound. Examples of such a member may include a case member constituting the housing of the electronic device1and a battery cover made of polycarbonate and attached detachably to the case member. One example is a box-shaped case member including a substantially rectangular bottom surface and side surfaces extending vertically from end portions of four sides of the bottom surface, and the piezoelectric element30may be attached to the bottom surface of the case member. In this example, the bottom surface of the case member is vibrated due to displacement of the piezoelectric element30to generate sound.

Although the embodiments of the present disclosure are described based on examples using a smartphone, using a smartphone is not mandatory. A mobile phone with one housing for operation and another housing for display which are connected in a foldable manner may also be used. Other examples of a mobile phone include a sliding-type with one housing for operation and another housing for display, both of which may be superposed or one of which may be slid in one direction, a turning-type with one housing for operation and another housing for display, one of which may be turned about an axis extending along a direction in which the housings are superposed, and a straight-type with one housing for operation and another housing for display, both of which are disposed in a singe housing and do not include a joint. A “two-axis hinge-type” mobile phone that may be flip opened and flip closed and turned may also be used.

The electronic device and the unit disclosed herein are described as having various functional parts configured to execute preferable functions. Note that the functional parts are merely illustrated schematically for simplification of description of the functionality and do not necessarily represent specific hardware or software. In this sense, any hardware or software that practically executes the preferable functions described herein may be implemented as the functional parts and other components. Various functions of different components may be achieved by any hardware and software used in combination or alone, and these may be adopted separately or in combination of two or more. Thus, various aspects of the present disclosure may be implemented in many different embodiments without departing from the scope of the present disclosure.

REFERENCE SIGNS LIST