Handheld device

Abstract

A handheld device is disclosed. A housing member includes a first surface and a second surface. A first sound emitting hole is located in the first surface. A second sound emitting hole is located in the second surface. A film speaker comprises a piezoelectric element and a resin film that vibrates together with the piezoelectric element. A speaker holder comprises the film speaker disposed at an angle in the speaker holder such that the front of the resin film faces the first sound emitting hole and is tilted from the first surface of the housing member toward the second sound emitting hole.

Claims

1 . A handheld device, comprising: a housing member including a first surface and a second surface, a first sound emitting hole being located in the first surface, a second sound emitting hole being located in a position corresponding to the first sound emitting hole in the second surface; a first film speaker comprising a piezoelectric element and a resin film that vibrates together with the piezoelectric element; and a first speaker holder comprising the first film speaker disposed at an angle in the first speaker holder such that the front of the resin film faces the first sound emitting hole and is tilted from the first surface toward the second sound emitting hole. 2 . The handheld device according to claim 1 , further comprising; a display; and a battery disposed on the back side of the display, wherein the first speaker holder retains the first film speaker on the back side of the battery. 3 . The handheld device according to claim 1 , further comprising a second film speaker. 4 . The handheld device according to claim 2 , further comprising a second film speaker. 5 . The handheld device according to claim 1 , wherein the first surface is a front surface or a rear surface, and the second surface is a side surface.
CROSS-REFERENCE TO RELATED APPLICATION [0001] The present application is a bypass continuation based on PCT Application No. PCT/JP2014/081060 filed on Nov. 25, 2014, which claims the benefit of Japanese Application No. 2013-243073, filed on Nov. 25, 2013. PCT Application No. PCT/JP2014/081060 is entitled “HANDHELD TERMINAL”, and Japanese Application No. 2013-243073 is entitled “HANDHELD DEVICE”. The contents of which are incorporated by reference herein in their entirety. FIELD [0002] Embodiments of the present disclosure relate to a handheld device, and more particularly relate to a handheld device with a built-in speaker. BACKGROUND [0003] A mobile terminal with a built-in speaker has conventionally been proposed. In the mobile terminal, the speaker is disposed at a given angle in a corner portion of a housing to achieve size and thickness reduction of the mobile terminal. SUMMARY [0004] A handheld device is disclosed. In one embodiment, a handheld device comprises a housing member including a first surface and a second surface, a first sound emitting hole located in the first surface of the housing member, a second sound emitting hole located in a position corresponding to the first sound emitting hole in the second surface of the housing member. A film speaker comprises a piezoelectric element and a resin film that vibrates together with the piezoelectric element. A speaker holder comprises the film speaker disposed at an angle in the speaker holder such that the front of the resin film faces the first sound emitting hole and is tilted from the first surface toward the second sound emitting hole. BRIEF DESCRIPTION OF DRAWINGS [0005] FIG. 1A illustrates an external view showing an example of an external appearance of a surface of a mobile device according to an embodiment of the disclosure. [0006] FIG. 1B illustrates an external view showing an external appearance of a back surface of the mobile device. [0007] FIG. 2A illustrates an explanatory diagram showing an example of an external appearance of a film speaker built in the mobile device illustrated in FIG. 1 when viewed from front. [0008] FIG. 2B illustrates an explanatory diagram showing an example of a section taken along a IIB-IIB line illustrated in FIG. 2A . [0009] FIG. 3 illustrates an exploded perspective view showing an example of an outline of an internal structure of the mobile device illustrated in FIG. 1 . [0010] FIG. 4A illustrates an explanatory diagram showing an example of a state of a mounting frame illustrated in FIG. 2A and FIG. 2B . [0011] FIG. 4B illustrates an explanatory diagram showing a state of the mounting frame when viewed from the back side. [0012] FIG. 5A illustrates an explanatory diagram showing an example of the front side of the mounting frame illustrated in FIGS. 2A and 2B to which a first film speaker and a second film speaker are attached, in which necessary parts are mounted. [0013] FIG. 5B illustrates an example of the back side of the mounting frame to which the first film speaker and the second film speaker are bonded. [0014] FIG. 5C illustrates an example of the back side of the mounting frame on which a substrate is disposed. [0015] FIG. 5D illustrates an example of the back side of the mounting frame in which a coupling member couples inner end portions, which face each other, of a first speaker holder and a second speaker holder. [0016] FIG. 6 illustrates an example of a section taken along a VI-VI line illustrated in FIG. 5D . [0017] FIG. 7A illustrates an example of a state of the mounting frame illustrated in FIG. 5D before the inner chassis is fit in the mounting frame. [0018] FIG. 7B illustrates an example of a state of the mounting frame illustrated in FIG. 7A after the inner chassis is fit in the mounting frame. [0019] FIG. 8 illustrates an example of a section taken along a VIII-VIII line illustrated in FIG. 7B . [0020] FIG. 9A illustrates an enlarged view showing an example of details of the first speaker holder and the second speaker holder illustrated in FIG. 4A viewed from the front side of the mounting frame. [0021] FIG. 9B illustrates an example of a state where the first film speaker and the second film speaker are bonded to the first speaker holder and the second speaker holder illustrated in FIG. 9A . [0022] FIG. 10 illustrates an explanatory diagram showing an example of a state of the first speaker holder and the second speaker holder illustrated in FIG. 9B when viewed from the back side and a state where a secondary battery is disposed on the front side of the mounting frame. [0023] FIG. 11 illustrates an example of a section taken along an XI-XI line illustrated in FIG. 10 . [0024] FIG. 12 illustrates an example of a section of another embodiment taken along the XI-XI line illustrated in FIG. 10 . [0025] FIG. 13A illustrates an example of a state of the mounting frame illustrated in FIG. 7B when viewed from the back side before the back panel is mounted on the mounting frame. [0026] FIG. 13B illustrates an example of a state of the mounting frame illustrated in FIG. 13A after the back panel is mounted on the mounting frame. [0027] FIG. 14 illustrates an example of a section taken along an XIV-XIV line illustrated in FIG. 10 . [0028] FIG. 15 illustrates an example of a state of second sound emitting holes of the mobile device illustrated in FIG. 1A and FIG. 1B when viewed from the side. DETAILED DESCRIPTION [0029] With reference to FIG. 1A and FIG. 1B , a mobile device (for example, a mobile phone) 10 in one embodiment is a smartphone as an example. An external appearance of the mobile device 10 includes a back panel 12 , part of a mounting frame 14 , and a front panel 16 so as to have an elongated flat rectangular shape, for example. Thus, the back panel 12 is the principal part of a housing member (member for forming a housing having a main surface and side surfaces). Note that it is possible to form the side surfaces of the housing member with part of the mounting frame 14 or the front panel 16 . It is previously pointed out that the disclosure is applicable to not only the smartphone but also any handheld devices such as a tablet PC (Personal Computer) and a PDA (Personal Digital Assistant). [0030] A touch panel 20 may be formed integrally with the front panel 16 . Further, a display 18 (display unit) includes, for example, liquid crystals or organic EL (Electro-Luminescence) bonded to a back surface of the front panel 16 . [0031] A hole 22 for inputting sound to a microphone located inside the mobile device 10 is positioned on the right side of a lower side surface of the mobile device 10 . A built-in piezoelectric element (not shown) for converting a sound signal to vibrations is included on the upper side of the mobile device 10 . For example, when a sound signal is input to the piezoelectric element, the piezoelectric element converts the sound signal to vibrations and directly vibrates the display 18 (front panel 16 ). This allows a user to hear the sound output from the display 18 . Since the sound is output in this manner, the mobile device 10 may not be supplied with a sound emitting hole for outputting a received voice, for example. [0032] A first film speaker 30 a and a second film speaker 30 b that are described below are built in the mobile device 10 . Sounds from the first film speaker 30 a and the second film speaker 30 b are output from not only two first sound emitting holes 24 a located in a back surface of the back panel 12 but also two second sound emitting holes 24 b located in side surfaces of the back panel 12 in one embodiment. The second sound emitting holes 24 b are formed in positions corresponding to the first sound emitting holes 24 a in the side surfaces of the back panel 12 . The following description clarifies the “corresponding positions.” [0033] A hole 26 connected to a charging terminal (not shown) located inside is located in the middle of the lower side surface of the mobile device 10 . [0034] For example, when an operation of a call is performed to start the voice call, a received voice is output from the front panel 16 by vibrations of the piezoelectric element mentioned above. On the other hand, a speaking voice of a user is input to the microphone through the hole 22 and transmitted to a phone at the other end of the call. When an incoming call from the other phone is notified, a ringer tone is output from a built-in film speaker. The first film speaker 30 a and the second film speaker 30 b are built in the mobile device 10 in one embodiment, so that a stereo sound can also be reproduced. [0035] When a charging connector is connected to the charging terminal through the hole 26 , a secondary battery 44 (see FIG. 3 ) of the mobile device 10 can be supplied with charging power from an external power supply. [0036] FIG. 2A illustrates an explanatory diagram showing an external appearance of a film speaker 30 used in one embodiment when viewed from the front. FIG. 2B illustrates a cross-sectional view taken along a IIB-IIB line illustrated in FIG. 2A . In addition, the film speaker 30 illustrated in this diagram is used as the first film speaker 30 a and the second film speaker 30 b built in the mobile device 10 , and thus descriptions are given here without differentiating between a first film speaker and a second film speaker. Hereinafter, to differentiate between the first film speaker and the second film speaker, reference numbers 30 a and 30 b are respectively used. [0037] The film speaker 30 is a flat rectangle and has a thickness of 0.7 mm, for example. The film speaker 30 comprises a piezoelectric element 32 having the same rectangular shape. The piezoelectric element 32 is located substantially in the center of the film speaker 30 when viewed from a surface of the film speaker 30 from which sound is output, namely, the front ( FIG. 2A ) of the film speaker 30 . The piezoelectric element 32 is resin-coated with a resin coating layer 34 . A resin film 36 is bonded to a surface of the resin coating layer 34 . A frame 38 is located on the periphery of the film speaker 30 to support the resin coating layer 34 and the resin film 36 . The application of a sound signal to the piezoelectric element 32 of such a film speaker 30 causes the piezoelectric element 32 to vibrate, and the vibrations are transmitted to the entire film speaker 30 comprising the resin coating layer 34 and the resin film 36 , so that the sound is output from the front of the film speaker 30 . In addition, the frame 38 is used when the film speaker 30 is fixed on a speaker holder 46 (described below). [0038] FIG. 3 illustrates an exploded perspective view showing an outline of an internal structure of the mobile device 10 . With reference to FIG. 3 , the mobile device 10 comprises the front panel 16 , the display 18 , an inner chassis 42 , the secondary battery 44 , the first film speaker 30 a and the second film speaker 30 b , the mounting frame 14 , a substrate 48 , a coupling member 56 , and the back panel 12 , and each part is mounted in the mobile device 10 in the stated order from the front (upper side in FIG. 3 ). The back panel 12 is mounted and cooperates with the mounting frame 14 to create space inside the back panel 12 , and thus sounds from the first film speaker 30 a and the second film speaker 30 b are emitted from the first sound emitting holes 24 a and the second sound emitting holes 24 b to the outside of the space. [0039] The main surface of the mobile device 10 includes the surface of the front panel 16 . The front panel 16 may be made of a glass so as to have an elongated flat rectangular shape, for example. As described above, the touch panel 20 may be formed integrally with the back surface of the front panel 16 . The display 18 is bonded to the back surface of the front panel 16 with an adhesive or an optical clear adhesive (OCA) tape. [0040] The inner chassis 42 comprises a rectangular resin frame and a shield plate 40 of metal (conductive material) located so as to cover almost the entire surface of the inside of the frame. The frame of the inner chassis 42 has a thickness equal to or slightly thinner than a thickness of a set of the shield plate 40 and the secondary battery 44 in layers. The front panel 16 to which the display 18 is bonded as described above is disposed on the front side of the inner chassis 42 , namely, the front side of the shield plate 40 . On the other hand, a recessed portion (not shown) for retaining the secondary battery 44 (allowing the secondary battery 44 to be fit therein) is provided on the back side of the inner chassis 42 . Therefore, the secondary battery 44 is disposed on the back side of the display 18 with respect to the shield plate 40 . The inner chassis 42 stably retains the secondary battery 44 on the back side of the display 18 . In addition, the inner chassis 42 , particularly the resin frame, is sometimes referred to as a battery retainer. [0041] FIG. 4A illustrates a plan view showing an example of the mounting frame 14 when viewed from the front (also referred to as the front side), and FIG. 4B illustrates a plan view showing an example of the mounting frame 14 when viewed from the back side. With reference to FIG. 4A and FIG. 4B together with FIG. 3 , the mounting frame 14 has a planar rectangular shape similarly to the front panel 16 and the inner chassis 42 . A frame comprising a pair of vertical frames 70 (first pair of frame members) and a pair of horizontal frames 72 (second pair of frame members) may be formed together with each part described below by resin molding. Hereinafter, one and the other of the vertical frames 70 in a pair are also referred to as a first vertical frame 70 a and a second vertical frame 70 b , respectively, and one and the other of the horizontal frames 72 in a pair are also referred to as a first horizontal frame 72 a and a second horizontal frame 72 b , respectively. The first vertical frame 70 a and the second vertical frame 70 b are disposed at a predetermined interval. The first horizontal frame 72 a connects the upper portions of the pair of the vertical frames 70 to each other. The second horizontal frame 72 b connects the lower portions of the pair of the vertical frames 70 to each other. [0042] A first speaker holder 46 a and a second speaker holder 46 b both having a plate shape are formed so as to extend inwardly respectively from the inside of the first vertical frame 70 a and the inside of the second vertical frame 70 b and to face each other in the direction in which they extend. Sound emitting holes 74 having a hexagonal shape, for example, are each formed in the center of the first speaker holder 46 a and the second speaker holder 46 b to emit sounds from the first film speaker 30 a and the second film speaker 30 b ( FIG. 5B , for example) retained in the first speaker holder 46 a and the second speaker holder 46 b. [0043] The first speaker holder 46 a and the second speaker holder 46 b have ribs 90 (see FIG. 9 ), which are described in detail below, on the peripheries of the front surfaces of the first speaker holder 46 a and the second speaker holder 46 b . The first speaker holder 46 a and the second speaker holder 46 b have the planar rectangular plate shape in one embodiment, but the shape of the first speaker holder 46 a and the second speaker holder 46 b is not limited to this. It suffices that the first speaker holder 46 a and the second speaker holder 46 b each have at least a region in which the frame 38 in FIG. 2A and FIG. 2B can be mounted (bonded). The sound emitting holes 74 may be larger or smaller. [0044] The inner chassis 42 is fit in the frame of the mounting frame 14 . Thus, the inner surfaces of the pair of vertical frames 70 and the pair of horizontal frames 72 have an interior wall surface 60 (also see FIGS. 6, 8, and 14 , for example) in which the inner chassis 42 can be fit. In other words, the interior wall surface 60 contacts the outer surface of the resin frame of the inner chassis 42 , so that the inner chassis 42 is fit in the mounting frame 14 . [0045] Moreover, the mounting frame 14 has a panel supporter 62 and an interior wall surface 64 (also see FIGS. 6, 8, and 14 , for example) for housing the front panel 16 and allowing the front panel 16 to be mounted thereon. The panel supporter 62 and the interior wall surface 64 as well as the interior wall surface 60 have a step shape. More specifically, the panel supporter 62 is a planar portion extending outwardly from an end of the interior wall surface 60 on the front side of the mounting frame 14 (an end toward the front of the paper plane in FIG. 4A and FIG. 4B , and an end on the lower side of the paper plane in FIG. 6 ). The interior wall surface 64 extends from the outer end of the panel supporter 62 to the front side (the side toward the front of the paper plane in FIG. 4A and FIG. 4B , and the lower side of the paper plane in FIG. 6 ). The peripheral portion of the front panel 16 is disposed on the panel supporter 62 . Thus, the front panel 16 is housed inside the interior wall surface 64 . [0046] A portion 66 (also see FIGS. 6, 8, and 14 , for example), which is located outside the interior wall surface 64 , of each of the pair of vertical frames 70 and the pair of horizontal frames 72 is an exposed portion that is exposed as the exterior appearance ( FIG. 1A and FIG. 1B ) of the mobile device 10 . Therefore, when the front panel 16 is mounted inside the interior wall surface 64 and on the panel supporter 62 , the front surface of the front panel 16 is in the same plane or substantially the same plane as (is flush with) the front surface of the outer portion 66 . [0047] Furthermore, a recessed portion 68 a (also see FIG. 14 , for example) is formed as a second fitting portion 68 (also see FIGS. 6, 8, and 14 , for example) on the back side of the mounting frame 14 (for example, the back portion of the pair of vertical frames 70 and the pair of horizontal frames 72 ). On the other hand, a protruding portion 58 a (also see FIG. 14 , for example) is formed as a first fitting portion 58 (also see FIG. 14 , for example) on the side surface of the back panel 12 . When the protruding portion 58 a is fit in the recessed portion 68 a , the back panel 12 is in the state of being mounted on the mounting frame 14 . [0048] An assembly portion 76 on which parts such as a camera module are assembled is located from the inside of the first horizontal frame 72 a to the upper ends of the first speaker holder 46 a and the second speaker holder 46 b . The assembly portion 76 has a rectangular hole 78 for allowing wiring to pass therethrough. Two substrate recessed portions 80 for allowing the substrate 48 with the shape illustrated in FIG. 3 to be disposed thereon are located in the assembly portion 76 on the back side ( FIG. 4B ) of the mounting frame 14 . As seen from FIG. 3 , the side surface of the second horizontal frame 72 b has a hole 22 a connected to the microphone and a hole 26 a connected to the charging terminal. [0049] Referring back to FIG. 3 , the substrate 48 is made of resin, glass fiber, or the like, and has a first portion 50 , a second portion 52 having a substantially rectangular shape, and a third portion 54 that has an elongated shape and connects the first portion 50 and the second portion 52 to each other. The substrate 48 comprises predetermined wiring formed thereon and comprises necessary parts such as the microphone mounted thereon. [0050] It should be noted that the shape and the size of the first portion 50 , the second portion 52 , and the third portion 54 of the substrate 48 are not limited to the shape and the size in one embodiment. [0051] The coupling member 56 is made of resin or the like and has a body portion and two locking portions 82 (see FIG. 6 ) located on each of the left and the right of the body portion. The coupling member 56 couples the inner end portions, which face each other, of the first speaker holder 46 a and the second speaker holder 46 b . A means of mounting the coupling member 56 is described in detail below. [0052] The side surfaces and the bottom surface (back surface) of the mobile device 10 as illustrated in FIG. 1A and FIG. 1B include a surface of the back panel 12 functioning as the housing member as described above. The back panel 12 may be made of resin so as to have a rectangular box shape. The main surface of the back panel 12 , namely, the bottom surface has the first sound emitting holes 24 a , and the left and right side surfaces of the back panel 12 have the second sound emitting holes 24 b . The lower side surface of the back panel 12 has a hole 22 b connected to the microphone and a hole 26 b connected to the charging terminal. [0053] The inner chassis 42 , the secondary battery 44 , the first film speaker 30 a , the second film speaker 30 b , the substrate 48 , and the coupling member 56 that are described above are mounted in the mounting frame 14 . Then, the front panel 16 is mounted on the front side of the mounting frame 14 in which they are mounted, and the back panel 12 is mounted on the back side of the mounting frame 14 . [0054] Next, a procedure for mounting parts in the mounting frame 14 is described. First, with reference to FIG. 5A and FIG. 5B , the first film speaker 30 a and the second film speaker 30 b are disposed at an angle in the first speaker holder 46 a and the second speaker holder 46 b such that the front (each of the surfaces from which sounds are emitted) of the first film speaker 30 a and the second film speaker 30 b faces the first sound emitting holes 24 a and is tilted from the bottom surface of the back panel 12 toward the second sound emitting holes 24 b . In other words, the first film speaker 30 a is tilted such that the front surface faces both of the first sound emitting holes 24 a and the second sound emitting holes 24 b . The first film speaker 30 a and the second film speaker 30 b are respectively bonded to the first speaker holder 46 a and the second speaker holder 46 b with bonding means such as a double-faced tape on the front side of the mounting frame 14 . At this time, the first film speaker 30 a and the second film speaker 30 b are bonded such that each of the surfaces from which sounds are emitted, namely, the front faces the corresponding sound emitting hole 74 . The bonding means such as the double-faced tape (OCA tape) bonds the frames 38 , which are illustrated in FIG. 2A and FIG. 2B , of the first film speaker 30 a and the second film speaker 30 b to the corresponding first speaker holder 46 a and second speaker holder 46 b . While the first film speaker 30 a and the second film speaker 30 b are bonded to the first speaker holder 46 a and the second speaker holder 46 b , the first film speaker 30 a and the second film speaker 30 b can be visually identified through the sound emitting holes 74 from the back side of the mounting frame 14 . [0055] With reference to FIG. 5C and FIG. 5D , the substrate 48 is disposed on the back side of the mounting frame 14 . At this time, the first portion 50 of the substrate 48 is disposed above the first speaker holder 46 a and the second speaker holder 46 b such that the first portion 50 overlaps part of the assembly portion 76 , and the second portion 52 is disposed below the first speaker holder 46 a and the second speaker holder 46 b . The third portion 54 passes between the first speaker holder 46 a and the second speaker holder 46 b and is disposed in substantially the same plane as the first film speaker 30 a and the second film speaker 30 b . As a result, the hole 78 and the substrate recessed portions 80 in the assembly portion 76 are covered with the substrate 48 . The substrate 48 is disposed on the back side of the mounting frame 14 so as to avoid the first film speaker 30 a and the second film speaker 30 b . Thus, for example, the first film speaker 30 a and the second film speaker 30 b can be disposed in the same plane or substantially the same plane as the substrate 48 , so that the thickness can be further reduced. Moreover, the third portion 54 connects the first portion 50 and the second portion 52 to each other, and the coupling member 56 over the third portion 54 couples the first speaker holder 46 a and the second speaker holder 46 b . Thus, the first speaker holder 46 a and the second speaker holder 46 b having great rigidity can be realized without reducing an area that can be used for the substrate 48 . [0056] Next, as illustrated in FIG. 5D , the coupling member 56 over the third portion 54 of the substrate 48 is locked to the first speaker holder 46 a and the second speaker holder 46 b such that the coupling member 56 couples the inner end portions, which face each other, of the first speaker holder 46 a and the second speaker holder 46 b. [0057] Specifically, with reference to FIG. 6 that is a cross-sectional view taken along a VI-VI line in FIG. 5D , each of the locking portions 82 located on the coupling member 56 has a hook on the tip. When the coupling member 56 on the back side of the mounting frame 14 is pushed from the upper side of the paper plane in FIG. 6 , the locking portions 82 are temporarily bent inwardly. When the coupling member 56 is further pressed and the tips of the locking portions 82 reach the front side of the mounting frame 14 , the shape of the locking portions 82 returns to the original shape. At this time, the hooks located on the tips of the locking portions 82 are caught on the peripheries of the first speaker holder 46 a and the second speaker holder 46 b , and thus the coupling member 56 is fixed between the first speaker holder 46 a and the second speaker holder 46 b. [0058] As a result, the first speaker holder 46 a and the second speaker holder 46 b are in the state of being firmly coupled together with the coupling member 56 , so that the first speaker holder 46 a and the second speaker holder 46 b have a both-end supported beam structure from a cantilever structure (the state in FIG. 4A and FIG. 4B , for example). In this manner, the first speaker holder 46 a and the second speaker holder 46 b are integrated, so that each of them has greater rigidity, and vibrations of the first speaker holder 46 a and the second speaker holder 46 b themselves can be suppressed. Thus, sound pressure levels of the first film speaker 30 a and the second film speaker 30 b can be increased. [0059] For example, in a case where the first speaker holder 46 a and the second speaker holder 46 b are not coupled together with the coupling member 56 , the first speaker holder 46 a and the second speaker holder 46 b remain in the cantilever structure, and the structure supporting the first film speaker 30 a and the second film speaker 30 b does not have great rigidity. If sounds are emitted from the first film speaker 30 a and the second film speaker 30 b in this state, the vibrations of the first film speaker 30 a and the second film speaker 30 b also cause the first speaker holder 46 a and the second speaker holder 46 b to vibrate, and the vibrations of the first speaker holder 46 a and the second speaker holder 46 b can diminish the vibrations of the first film speaker 30 a and the second film speaker 30 b . On the other hand, if the first speaker holder 46 a and the second speaker holder 46 b are coupled together with the coupling member 56 and have the both-end supported beam structure as in one embodiment, approximately 3 dB of improvement in the sound pressure can be seen. [0060] As illustrated in FIG. 6 , the mounting frame 14 is tilted from the center toward the first vertical frame 70 a and the second vertical frame 70 b , and the central portion is located higher than the first vertical frame 70 a and the second vertical frame 70 b . In a case where the back panel 12 is mounted on the mounting frame 14 , an adhesive is applied to the coupling member 56 , and the coupling member 56 and the back panel 12 are bonded together. In other words, the coupling member 56 is also fixed on the back panel 12 . Therefore, the first speaker holder 46 a and the second speaker holder 46 b are reinforced also with the back panel 12 , and the further improvement in the sound pressure is promising. [0061] In another embodiment, the coupling member 56 may have a recessed portion to suppress a leak of the adhesive applied to the coupling member 56 . [0062] FIG. 7A illustrates an explanatory diagram showing a state of the mounting frame 14 illustrated in FIG. 5D before the inner chassis 42 is fit in the mounting frame 14 . FIG. 7A illustrates a diagram when viewed from the front (front side), and the substrate 48 and the coupling member 56 are mounted on the mounting frame 14 in one example of FIG. 7A . In this state, part of the substrate 48 is seen through the hole 78 . Further, the hooks on the tips of the locking portions 82 of the coupling member 56 are caught on the right side of the first speaker holder 46 a and the left side of the second speaker holder 46 b . As illustrated in FIG. 7A , the coupling member 56 couples the first speaker holder 46 a and the second speaker holder 46 b such that the locking portions 82 are fit in part of slits 92 (described below) of the first speaker holder 46 a and the second speaker holder 46 b. [0063] With reference to FIG. 7B , the inner chassis 42 retaining the secondary battery 44 is fit in the mounting frame 14 in this state, and thus the inner chassis 42 covers the substrate 48 , the first film speaker 30 a , the second film speaker 30 b , the first speaker holder 46 a , the second speaker holder 46 b , or the like. In FIG. 7B , the secondary battery 44 is indicated by a broken line. [0064] With reference to FIG. 8 illustrating a cross-sectional view taken along a VIII-VIII line in FIG. 7B , it is clearly seen that the inner chassis 42 retains the secondary battery 44 . The secondary battery 44 is disposed on the mounting frame 14 and the shield plate 40 , so that the secondary battery 44 is difficult to come off the inner chassis 42 . [0065] Then, the first film speaker 30 a and the second film speaker 30 b are in the state of being retained on the back side of the secondary battery 44 by the first speaker holder 46 a and the second speaker holder 46 b . In other words, the first speaker holder 46 a and the second speaker holder 46 b stably retain the first film speaker 30 a and the second film speaker 30 b on the back side of the secondary battery 44 . [0066] In this manner, the mobile device 10 as a whole can be reduced in thickness by using the film speakers and disposing the film speakers on the back side of the secondary battery. [0067] As illustrated in FIG. 8 , the inner chassis 42 retaining the secondary battery 44 is fit in the interior wall surface 60 of the mounting frame 14 . The frame of the inner chassis 42 has a thickness including a thickness of the shield plate 40 and a thickness of part of the secondary battery 44 . The mounting frame 14 has a thickness including the thickness of the shield plate 40 , the thickness of the inner chassis 42 , and the thickness of the secondary battery 44 . Thus, even when the inner chassis 42 including the secondary battery 44 fit therein is fit in the mounting frame 14 , the thickness of the mounting frame 14 remains unchanged. In other words, the secondary battery 44 and the inner chassis 42 are completely housed inside the mounting frame 14 and do not protrude from the mounting frame 14 . This configuration also allows the mobile device 10 as a whole to be reduced in thickness. [0068] FIG. 9A and FIG. 9B illustrate enlarged views showing details of the first speaker holder 46 a and the second speaker holder 46 b . With reference to FIG. 9A , the peripheries of the first speaker holder 46 a and the second speaker holder 46 b are surrounded by the ribs 90 . The ribs 90 have a height set to be higher than a thickness (height) of the first film speaker 30 a and the second film speaker 30 b bonded to the first speaker holder 46 a and the second speaker holder 46 b . Therefore, when the first film speaker 30 a and the second film speaker 30 b are bonded to the first speaker holder 46 a and the second speaker holder 46 b , the ribs 90 are higher than the first film speaker 30 a and the second film speaker 30 b . In other words, the ribs 90 protrude to the front side (toward the secondary battery 44 ) more than the first film speaker 30 a and the second film speaker 30 b . The rib 90 of the first speaker holder 46 a has slits 92 at a total of 12 places including 4 places on the upper side, 4 places on the lower side, and 4 places on the right side (center side of the mobile device 10 ). The rib 90 of the first speaker holder 46 a has a wiring recessed portion 94 on the right side thereof to allow wiring connected to the first film speaker 30 a to pass through the wiring recessed portion 94 . Similarly, the rib 90 of the second speaker holder 46 b has the slits 92 at a total of 12 places including 4 places on the upper side, 4 places on the lower side, and 4 places on the left side (center side of the mobile device 10 ), and has the wiring recessed portion 94 on the left side of the rib 90 . The slits 92 are disposed at an interval on the periphery of each of the first speaker holder 46 a and the second speaker holder 46 b . The slits 92 have openings on the secondary battery 44 side while penetrating the ribs 90 in a parallel direction to the substrate 48 (in a parallel direction to the paper plane of FIG. 9 ). It should be noted that the number and the size (length or width) of the slits 92 are not limited to those in one embodiment. [0069] With reference to FIG. 9B , when the first film speaker 30 a and the second film speaker 30 b are mounted in the first speaker holder 46 a and the second speaker holder 46 b , the first speaker holder 46 a and the second speaker holder 46 b retain the first film speaker 30 a and the second film speaker 30 b while the ribs 90 surround the first film speaker 30 a and the second film speaker 30 b. [0070] FIG. 10 illustrates a diagram of the first speaker holder 46 a and the second speaker holder 46 b illustrated in FIG. 9B when viewed from the back side. In one example of FIG. 9B , the secondary battery 44 is disposed on the front side of the mounting frame 14 . In this state, the front of the first film speaker 30 a and the front of the second film speaker 30 b are seen through the sound emitting holes 74 of the first speaker holder 46 a and the second speaker holder 46 b . The first film speaker 30 a and the second film speaker 30 b are in the state of being disposed on the back side of the secondary battery 44 . [0071] FIG. 11 illustrates a cross-sectional view taken along an XI-XI line in FIG. 10 and mainly illustrates a section of the rib 90 of the first speaker holder 46 a retaining the first film speaker 30 a . With reference to FIG. 11 , the upper end face (lower side in FIG. 11 ) of the rib 90 faces the back surface of the secondary battery 44 . The rib 90 is higher than the first film speaker 30 , and thus substantially the entire first film speaker 30 a is covered with the rib 90 and part of the first film speaker 30 a can be confirmed through the slits 92 in the cross-sectional view. The upper end face of the rib 90 higher than the first film speaker 30 a faces the secondary battery 44 , to thereby keep a gap between the secondary battery 44 and the first film speaker 30 a . In other words, in a case where the secondary battery 44 is expanded over time by being repeatedly charged and discharged, the rib 90 functions as a stopper and the upper end face of the rib 90 contacts the main surface of the expanded secondary battery 44 . Therefore, the main surface of the secondary battery 44 is difficult to be further displaced toward the first film speaker 30 a . Therefore, the rib 90 can stably keep the gap between the first film speaker 30 a and the secondary battery 44 . [0072] With the rib 90 surrounding the first film speaker 30 a , the inner space and the outer space of the rib 90 that houses the first film speaker 30 a or the second film speaker 30 b communicate with each other through the slits 92 . Thus, a rear volume of the first film speaker 30 a can be sufficiently kept, and acoustic performance of the first film speaker 30 a can be improved. [0073] The rib 90 located on the upper side and the left side (center side) of the first speaker holder 46 a , the rib 90 of the second speaker holder 46 b , and the second film speaker 30 b are substantially the same as those in FIG. 11 , and thus detailed drawings are omitted. [0074] With reference to FIG. 12 , in another embodiment, the first speaker holder 46 a (for example, the rib 90 ) may be fixed on (bonded to) the secondary battery 44 with a fixing portion such as an adhesive 96 or fixing means to further improve the sound pressure level of the first film speaker 30 a . The first speaker holder 46 a is fixed on the secondary battery 44 by using the secondary battery 44 having the greatest weight in the mobile device 10 and great rigidity as in one embodiment. [0075] The second speaker holder 46 b (for example, the rib 90 ) may be bonded to the secondary battery 44 with the adhesive 96 or the like similarly to the first speaker holder 46 a , which is omitted from the diagram. [0076] In one embodiment in FIG. 11 as described above, the rib 90 , for example, is fixed on the secondary battery 44 , and the rib 90 and the secondary battery 44 are integrated, so that the rigidity of the first speaker holder 46 a and the second speaker holder 46 b is reinforced with the rigidity of the secondary battery 44 , to thereby further increase the rigidity of the first speaker holder 46 a and the second speaker holder 46 b . As a result, the vibrations of the first speaker holder 46 a and the second speaker holder 46 b caused by the vibrations of the first film speaker 30 a and the second film speaker 30 b can be suppressed. Consequently, the sound pressure levels of the first film speaker 30 a and the second film speaker 30 b can be increased. [0077] By fixing the first speaker holder 46 a and the second speaker holder 46 b on the secondary battery 44 , the first film speaker 30 a and the second film speaker 30 b can keep a fixed distance from the secondary battery 44 at the occurrence of the phenomenon in which the secondary battery 44 is expanded over time by being repeatedly charged and discharged. Thus, variations in the rear volume of the first film speaker 30 a and the second film speaker 30 b can be suppressed. [0078] In one embodiment in FIG. 11 , the first speaker holder 46 a and the second speaker holder 46 b may be fixed on the secondary battery 44 with a double-faced tape or a fitting (locking) mechanism. [0079] FIG. 13A illustrates a diagram of the mounting frame 14 illustrated in FIG. 7B when viewed from the back side and illustrates a state of the mounting frame 14 before the back panel 12 is mounted thereon. The inner chassis 42 , the secondary battery 44 , or the like mounted on the front side of the mounting frame 14 are covered with the first speaker holder 46 a , the second speaker holder 46 b , the substrate 48 , the pair of vertical frames 70 , the pair of horizontal frames 72 , the assembly portion 76 , or the like. [0080] With reference to FIG. 13B , when the back panel 12 is mounted on the mounting frame 14 in this state, the back panel 12 covers the first film speaker 30 a , the second film speaker 30 b , the first speaker holder 46 a , the second speaker holder 46 b , the substrate 48 , the coupling member 56 , the second fitting portion 68 , the pair of vertical frames 70 , the pair of horizontal frames 72 , the sound emitting holes 74 , and the assembly portion 76 . At this time, the front of the first film speaker 30 a and the second film speaker 30 b (the front of the resin films 36 ) faces the first sound emitting holes 24 a located in the bottom surface of the back panel 12 . [0081] FIG. 14 illustrates a cross-sectional view taken along a XIV-XIV line in FIG. 13B . With reference to FIG. 14 , the first film speaker 30 a is disposed at an angle so as to be tilted from the bottom surface of the back panel 12 toward the second sound emitting holes 24 b . The tilt is described with reference to a vertical direction to the paper plane of FIG. 14 (perpendicular direction to the bottom surface of the back panel 12 ) and a lateral direction to the paper plane of FIG. 14 (parallel direction to the bottom surface of the back panel 12 ). The first film speaker 30 a comes closer to the second sound emitting holes 24 b closest to the first film speaker 30 a in the lateral direction to the paper plane while being tilted farther from the first sound emitting holes 24 a in the vertical direction to the paper plane. As illustrated in FIG. 15 , when the back panel 12 is viewed from the side, the first film speaker 30 a (or the second film speaker 30 b ) indicated by the broken line is in the state of being disposed behind the second sound emitting holes 24 b . In other words, in FIG. 14 , at least part of the first sound emitting holes 24 a are located in a region extending from the front of the first film speaker 30 a in the vertical direction of the paper plane while at least part of the second sound emitting holes 24 b are located in a region extending from the front of the first film speaker 30 a in the lateral direction of the paper plane. Moreover, the positional relationship can be put in another way by using a first plane perpendicular to the paper plane of FIG. 14 and parallel to the lateral direction of the paper plane and a second plane perpendicular to the paper plane of FIG. 14 and parallel to the vertical direction of the paper plane. That is to say, if the front of the first film speaker 30 a and the first sound emitting holes 24 a are projected onto the first plane, the projected portion of the first film speaker 30 a that is projected onto the first plane overlaps at least part of the projected portion of the first sound emitting holes 24 a that is projected onto the first plane. Furthermore, if the front of the first film speaker 30 a and the second sound emitting holes 24 b are projected onto the second plane, the projected portion of the first film speaker 30 a that is projected onto the second plane overlaps at least part of the projected portion of the second sound emitting holes 24 b that is projected onto the second plane. [0082] Referring back to FIG. 14 , the space created by the back panel 12 cooperating with the mounting frame 14 functions as a duct for letting out sounds from the bottom surface of the back panel 12 and a duct for letting out sounds from the side surfaces of the back panel 12 . The sounds output from the first film speaker 30 a are then output from the first sound emitting holes 24 a located in the front of the first film speaker 30 a and output from the second sound emitting holes 24 b located in the side surfaces of the back panel 12 correspondingly to the first sound emitting holes 24 a . In other words, a flow of the sounds output from the first film speaker 30 a includes two directions. In this state, in a case where a sound of a monophonic sound is output from the first film speaker 30 a and the second film speaker 30 b , the sound is emitted from two places in the rear surface and two places in the side surface of the housing member, and the output sound spreads in the surroundings. In other words, a surround effect can be provided to the sounds output from the first film speaker 30 a and the second film speaker 30 b . In a case where a sound of a stereo sound is output from the first film speaker 30 a and the second film speaker 30 b , left and right sounds that are each output particularly from the two places of the side surface are almost independent of each other to reach ears of a user. In other words, independence of the left and right sounds output from the first film speaker 30 a and the second film speaker 30 b is increased, so that sounds having a greater degree of separation between the left and right and having a greater stereo effect can be output. As described above, sounds providing a sense of realism can be output in one embodiment. [0083] The first film speaker 30 a is disposed at an angle inside the back panel 12 , and thus the sounds output from the first film speaker 30 a are sufficiently transmitted to not only the bottom surface of the back panel 12 but also the side surfaces of the back panel 12 . As a result, sound pressure from the side direction of the back panel 12 can be highly maintained, so that the volume of the sounds output from the second sound emitting holes 24 b can be increased. [0084] The second film speaker 30 b and the first sound emitting holes 24 a and the second sound emitting holes 24 b , which are located corresponding to the second film speaker 30 b , are substantially the same as those in FIG. 14 , and thus detailed drawings are omitted. [0085] The shape of the first sound emitting holes 24 a and the second sound emitting holes 24 b is not limited to only a circle or a rectangle, and the first sound emitting holes 24 a and the second sound emitting holes 24 b may have various shapes in another embodiment. In one embodiment described above, the back panel 12 has a box shape having corners (namely, a shape having side surfaces orthogonal to a main surface) and the second sound emitting holes 24 b are located in the perpendicular side surfaces, but the corner portions may be rounded off, that is to say, the side surfaces may be tilted or bent with respect to the main surface. Also in this case, the second sound emitting holes 24 b may be located in the tilted or bent side surfaces in positions corresponding to the side surfaces in one embodiment. [0086] In one embodiment described above, the back panel 12 includes the main surface and the side surfaces of the housing member, but the back panel 12 may include only the main surface and the second sound emitting holes 24 b may be located in the mounting frame 14 in a case where, for example, the mounting frame 14 instead of the back panel 12 includes the side surfaces. Further, in a case where, for example, the front panel 16 includes the side surfaces of the housing member, the second sound emitting holes 24 b may be located in the front panel 16 . [0087] In one embodiment described above, the substrate 48 includes the first portion 50 , the second portion 52 , and the third portion 54 , but the shape of the substrate 48 may be modified in various ways. [0088] For example, the substrate 48 may be formed as one large rectangular substrate and may be disposed so as to overlap the mounting frame 14 . In this case, it cannot be expected that the substrate 48 is reduced in thickness by being disposed between the first film speaker 30 a and the second film speaker 30 b , but the first speaker holder 46 a and the second speaker holder 46 b do not need to be located separately. Thus, the both-end supported beam structure is applicable as the structure of the first speaker holder 46 a and the second speaker holder 46 b without using the coupling member 56 , which can increase the rigidity. [0089] Alternatively, the substrate may have only a part corresponding to only the second portion 50 . Also in this case, the first speaker holder 46 a and the second speaker holder 46 b that are integrated can be formed while the coupling member 56 is omitted. [0090] In one embodiment, the first film speaker 30 a , the second film speaker 30 b , and the ribs 90 have the rectangular shape, but at least any one of them may have a circular shape or another shape instead of the rectangular shape in another embodiment. [0091] In one embodiment, the ribs 90 are formed so as to surround the first film speaker 30 a and the second film speaker 30 b , that is to say, the ribs 90 are formed all around the first film speaker 30 a and the second film speaker 30 b . In still another embodiment, the ribs 90 may include only ribs corresponding to at least one side of the first film speaker 30 a and the second film speaker 30 b . The ribs 90 may not surround the first film speaker 30 a and the second film speaker 30 b. [0092] One embodiment described above comprises the two film speakers 30 a , 30 b , but the film speaker 30 may comprise only one of them to further reduce the handheld device in size or to further increase the inner space. In this case, only one group of the first sound emitting holes 24 a are located in the main surface of the housing member, and only one group of the second sound emitting holes 24 b are located in positions corresponding to the first sound emitting holes 24 a in the side surface of the housing member. In the case where only one film speaker 30 is used as described above, sounds may be output from both of the first sound emitting holes 24 a and the second sound emitting holes 24 b located at some distance from the first sound emitting holes 24 a , thereby providing a better sense of realism than the case where only the first sound emitting holes 24 a are formed. [0093] Any specific numeric values in the disclosure are merely an example, and may be changed suitably according to modifications of specifications of products. [0094] Some examples of the points in one embodiment are summarized below. In a first aspect of one embodiment, a handheld device comprises a housing member including a main surface and a side surface, a first sound emitting hole formed in the main surface, a second sound emitting hole formed in a position corresponding to the first sound emitting hole in the side surface, a film speaker comprising a piezoelectric element and a resin film that vibrates together with the piezoelectric element, and a speaker holder comprising the film speaker disposed at an angle in the speaker holder such that the front of the resin film faces the first sound emitting hole and is tilted from the main surface toward the second sound emitting hole. [0095] A second aspect of one embodiment is dependent on the first aspect. The handheld device further comprises a display and a battery disposed on the back side of the display. The speaker holder retains the film speaker on the back side of the battery. [0096] A third aspect of one embodiment is dependent on the first aspect or the second aspect. The film speaker comprises two film speakers. [0097] The disclosure is described in detail, but the above description is the exemplification in all aspects and embodiments of the present disclosure are not intended to be limited thereto. It is construed that numerous modifications which are not exemplified can be envisaged without departing from the scope of the present disclosure.

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