Audio devices

Abstract

We provide an acoustic device that can divide a space while simultaneously emitting sound. [Solution] The acoustic device 10 comprises a diaphragm 30 having a first main surface 301, a second main surface 302 located on the opposite side of the first main surface 301, and an end surface 303 located between the first main surface 301 and the second main surface 302, and a vibrator 85 attached to the diaphragm 30. The end surface 303 has a first end surface 303c and a second end surface 303d which is different from the first end surface 303c. The vibrator 85 has a first vibrating surface 87a and a second vibrating surface 87b located on the opposite side of the first vibrating surface 87a. The first vibrating surface 87a is in contact with the first end surface 303c. The second vibrating surface 87b is in contact with the second end surface 303d.

Description

Technical Field

[0001] The present disclosure relates to an acoustic device.

Background Art

[0002] Conventionally, when partitioning a space by providing a partitioning member such as a partition, technologies for reducing noise by the partitioning member have been developed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, if the partitioning member can emit sounds such as music from the partitioning member itself, the utility value of the partitioning member can be enhanced.

[0005] The present disclosure has been made in consideration of such points, and an object thereof is to provide an acoustic device that can partition a space and emit sounds.

Means for Solving the Problems

[0006] Embodiments of the present disclosure relate to the following [1] to [8].

[0007] [1] An acoustic device, comprising: a diaphragm having a first main surface, a second main surface located on the opposite side of the first main surface, and an end surface located between the first main surface and the second main surface; a vibrator attached to the diaphragm; the end surface has a first end surface and a second end surface different from the first end surface; The oscillator has a first vibration surface and a second vibration surface located on the opposite side of the first vibration surface. The first vibrating surface is in contact with the first end face, The second vibrating surface is in contact with the second end face of the acoustic device.

[0008] [2] The acoustic device according to [1], wherein the vibrator vibrates along the direction normal to the first end face and the direction normal to the second end face.

[0009] [3] The acoustic device according to [1] or [2], wherein the diaphragm is rolled into a tubular shape.

[0010] [4] The acoustic device according to [3], wherein the radius of curvature of the diaphragm is 10 mm or more and 500 mm or less.

[0011] [5] The acoustic device according to any one of [1] to [4], wherein the thickness of the diaphragm is 100 μm or more and 500 μm or less.

[0012] [6] The first end face includes a first contact surface that contacts the first vibrating surface, and a first protruding surface that is adjacent to the first contact surface and protrudes further toward the second vibrating surface than the first contact surface. The acoustic device according to any one of [1] to [5], wherein the second end face includes a second contact surface that contacts the second vibrating surface and a second protruding surface that is adjacent to the second contact surface and protrudes toward the first vibrating surface than the second contact surface.

[0013] [7] The first end face is located on the opposite side of the first protruding surface when viewed from the first contact surface, and further includes a first recessed surface that is recessed on the opposite side of the first contact surface from the second contact surface, The acoustic device according to [6], wherein the second end face is located on the opposite side of the second protruding surface when viewed from the second contact surface, and further includes a second recessed surface that is recessed on the opposite side of the second contact surface from the first contact surface.

[0014] [8] The diaphragm includes a first antireflection layer that constitutes the first main surface and a second antireflection layer that constitutes the second main surface, and the acoustic device according to any one of [1] to [7].

Effect of the Invention

[0015] According to the present disclosure, an acoustic device can emit sound while partitioning a space.

Brief Description of the Drawings

[0016] [Figure 1] FIG. 1 is a perspective view showing an acoustic device according to the present embodiment. [Figure 2] FIG. 2 is a plan view showing an acoustic device according to the present embodiment. [Figure 3] FIG. 3 is a side view (a view taken along the arrow III in FIG. 2) showing an acoustic device according to the present embodiment. [Figure 4] FIG. 4 is a developed view showing a transparent laminated film of an acoustic device according to the present embodiment. [Figure 5] FIG. 5 is a schematic diagram for explaining the operation of an acoustic device as a comparative example. [Figure 6] FIG. 6 is a schematic diagram for explaining the operation of an acoustic device according to the present embodiment. [Figure 7] FIG. 7 is a side view (a side view corresponding to FIG. 3) showing an acoustic device according to the present embodiment, and shows a state before the vibrator is attached to the transparent laminated film. [Figure 8] FIG. 8 is a plan view showing an acoustic device according to the present embodiment, and shows a state before the vibrator is attached to the transparent laminated film. [Figure 9] FIG. 9 is a side view (a side view corresponding to FIG. 3) showing an acoustic device according to the present embodiment, and shows a state after the vibrator is attached to the transparent laminated film. [Figure 10]Figure 10 is a plan view showing the acoustic device according to this embodiment, and shows the state after the vibrator has been attached to the transparent laminated film. [Figure 11] Figure 11 is a perspective view showing an acoustic device according to this embodiment, and is a diagram showing another example of a method for mounting the transducer. [Figure 12] Figure 12 is a side view (corresponding to Figure 3) showing an acoustic device according to this embodiment, and is a diagram showing another example of a method for mounting the transducer. [Figure 13] Figure 13 is a side view (corresponding to Figure 3) showing a transparent laminated film of the acoustic device according to this embodiment, and is a diagram showing another example of a method for joining transparent laminated films together. [Figure 14] Figure 14 is a plan view showing an acoustic device according to this embodiment, and is a diagram showing another example of a method for mounting the transducer. [Figure 15A] Figure 15A is a cross-sectional view showing an example of the layer configuration of a transparent laminated film with a protective film according to this embodiment. [Figure 15B] Figure 15B is a cross-sectional view showing another example of the layer configuration of the transparent laminated film with protective film according to this embodiment. [Figure 15C] Figure 15C is a cross-sectional view showing another example of the layer configuration of the transparent laminated film with protective film according to this embodiment. [Figure 15D] Figure 15D is a cross-sectional view showing another example of the layer configuration of the transparent laminated film with protective film according to this embodiment. [Figure 15E] Figure 15E is a cross-sectional view showing another example of the layer configuration of the transparent laminated film with protective film according to this embodiment. [Figure 15F] Figure 15F is a cross-sectional view showing another example of the layer configuration of the transparent laminated film with protective film according to this embodiment. [Figure 16] Figure 16 is a diagram illustrating the puncture resistance test. [Figure 17] Figure 17 is a perspective view showing a modified example of the acoustic device according to this embodiment. [Figure 18]Figure 18 is an unfolded view showing a transparent laminated film of a modified example of the acoustic device according to this embodiment. [Figure 19] Figure 19 is a perspective view showing another modification of the acoustic device according to this embodiment. [Figure 20] Figure 20 is a plan view showing another modification of the acoustic device according to this embodiment. [Figure 21] Figure 21 is a perspective view showing another modification of the acoustic device according to this embodiment. [Figure 22] Figure 22 is a plan view showing another modification of the acoustic device according to this embodiment. [Figure 23] Figure 23 is a plan view showing another modification of the acoustic device according to this embodiment. [Figure 24] Figure 24 is a schematic diagram illustrating the operation of another modified version of the acoustic device according to this embodiment. [Figure 25] Figure 25 is a plan view showing another modification of the acoustic device according to this embodiment. [Figure 26] Figure 26 illustrates the sound pressure measurement method in the embodiment. [Figure 27] Figure 27 is a perspective view showing another example of how the sound device according to this embodiment is used. [Figure 28] Figure 28 is a perspective view showing another example of how the acoustic device according to this embodiment is used. [Figure 29] Figure 29 is a perspective view showing another example of how the acoustic device according to this embodiment is used. [Figure 30] Figure 30 is a perspective view showing another example of how the acoustic device according to this embodiment is used. [Figure 31] Figure 31 is a perspective view showing another example of how the acoustic device according to this embodiment is used. [Figure 32] Figure 32 is a perspective view showing another example of how the acoustic device according to this embodiment is used. [Modes for carrying out the invention]

[0017] This embodiment will be described below with reference to the drawings. Figures 1 to 16 are diagrams illustrating this embodiment. The following figures are schematic representations. Therefore, the size and shape of each part are exaggerated as appropriate to facilitate understanding. Furthermore, it can be modified as appropriate without departing from the technical concept. In the following figures, the same parts are denoted by the same reference numerals, and some detailed explanations may be omitted. In addition, the numerical values ​​such as dimensions and material names of each component described in this specification are examples of embodiments and can be selected and used as appropriate without being limited thereto. In this specification, terms that specify shapes and geometric conditions, such as parallel, orthogonal, and perpendicular, will be interpreted to include not only their strict meaning but also substantially the same state.

[0018] <Sound equipment> First, the acoustic device according to this disclosure will be described. Figures 1 to 3 show an example of the acoustic device 10 according to this embodiment. In this specification, "up" and "down" refer to the upper and lower parts, respectively, when the acoustic device 10 is in an upright position (Figure 1).

[0019] The sound device 10 according to this embodiment can be used, for example, as a showcase that balances protection and visibility of its contents (exhibits), and is capable of emitting sound. As shown in Figure 1, the sound device 10 is placed, for example, in a room R. This sound device 10 can be used to divide the space of room R into space R1 and space R2. The sound device 10 may also be placed on a desk T located in room R.

[0020] As shown in Figures 1 to 3, the acoustic device 10 comprises a transparent laminated film (diaphragm, hereinafter also referred to as transparent film) 30 and a transducer 85 attached to the transparent film 30. In the illustrated example, the acoustic device 10 comprises one transparent film 30 and one transducer 85. Of these, the transparent film 30 is placed directly on the desk T (see Figure 1). Although not shown, the acoustic device 10 may further include a support part for supporting the transparent laminated film 30, and the transparent film 30 may be placed on the desk T via a support part not shown.

[0021] The transparent film 30 is rolled into a tubular shape so that a pair of main surfaces (the first main surface 301 and the second main surface 302, described later) are curved. As shown in Figure 4, when the transparent film 30 is unfolded, it has a rectangular shape. That is, the transparent film 30 has an upper end 30a, a lower end 30b, a first side end (first end) 30c, and a second side end (second end) 30d. The upper end 30a and the lower end 30b extend between the first side end (first end) 30c and the second side end (second end) 30d. In other words, the first side end (first end) 30c and the second side end (second end) 30d extend between the upper end 30a and the lower end 30b. The shape of the transparent laminated film 30 is not particularly limited and can be determined as appropriate according to the shape of the space partitioned by the sound device 10. In this specification, the upper end portion 30a refers to the area of ​​the rectangular transparent film 30 that is within 30 mm of the upper end surface 303a, which will be described later. Similarly, the lower end portion 30b refers to the area of ​​the rectangular transparent film 30 that is within 30 mm of the lower end surface 303b, which will be described later. Furthermore, the first side end portion 30c refers to the area of ​​the rectangular transparent film 30 that is within 30 mm of the first side end surface 303c, which will be described later. In addition, the second side end portion 30d refers to the area of ​​the rectangular transparent film 30 that is within 30 mm of the second side end surface 303d, which will be described later.

[0022] Furthermore, in this embodiment, the upper end portion 30a and the lower end portion 30b, and the first side end portion 30c and the second side end portion 30d are perpendicular to each other. That is, the upper end portion 30a and the lower end portion 30b extend along the horizontal direction, while the first side end portion 30c and the second side end portion 30d extend along the vertical direction.

[0023] The transparent laminated film 30 has a first main surface 301, a second main surface 302 located on the opposite side of the first main surface 301, and an end surface 303 located between the first main surface 301 and the second main surface 302. The first main surface 301 and the second main surface 302 are parallel to each other.

[0024] The end face 303 has an upper end face 303a located at the upper end 30a and a lower end face 303b located at the lower end 30b opposite to the upper end 30a. The end face 303 also has a first side end face (first end face) 303c located at the first side end 30c and a second side end face (second end face) 303d which is different from the first side end face (first end face) 303c. Of these, the second side end face (second end face) 303d is located at the second side end 30d opposite to the first side end 30c.

[0025] Referring again to Figures 1 to 3, as described above, the transparent film 30 is rolled into a tubular shape so that the first main surface 301 and the second main surface 302 are curved. In this embodiment, the transparent film 30 is rolled into a cylindrical shape. In the illustrated example, the transparent film 30 is rolled so that the first main surface 301 is located on the inside of the transparent film 30 (sound device 10) and the second main surface 302 is located on the outside of the transparent film 30 (sound device 10). The first side end surface 303c and the second side end surface 303d face each other. The vibrator 85 described above is attached to the first side end surface 303c and the second side end surface 303d.

[0026] In this case, when viewed along the normal direction of the first end face 303c (the depth direction of the paper in Figure 1), the first end face 30c is not curved. Similarly, when viewed along the normal direction of the second end face 303d (the depth direction of the paper in Figure 1), the second end face 30d is not curved. On the other hand, when viewed along the normal direction of the upper end face 303a (lower end face 303b) (vertical direction), the upper end face 30a (lower end face 30b) is curved. That is, in a plan view, the first main surface 301 and the second main surface 302 are curved such that the upper end face 30a (lower end face 30b) of the transparent film 30 forms a circle. The radius of curvature r of the transparent film 30 (see Figure 2) may be 10 mm or more and 1000 mm or less, or 40 mm or more and 500 mm or less. By having a radius of curvature r of 10 mm or more and 1000 mm or less, the sound pressure and self-supporting properties of the sound emitted from the transparent film 30 can be increased. By having a radius of curvature r of 40 mm or more and 500 mm or less, the sound pressure and self-supporting properties of the sound emitted from the transparent film 30 can be further increased.

[0027] As described above, a sound-generating transducer 85 is attached to the transparent film 30. This transducer 85 is a piezoelectric element made of a piezoelectric ceramic material such as PZT (lead zirconate titanate). This piezoelectric element vibrates when a voltage is applied to it. When an audio signal is transmitted to the piezoelectric element as an electrical signal, the piezoelectric element vibrates in response to that signal. The vibration from the transducer 85 then generates sound from the entire transparent laminated film 30.

[0028] As shown in Figures 2 and 3, the oscillator 85 has a first vibration surface 87a and a second vibration surface 87b located on the opposite side of the first vibration surface 87a. The first vibration surface 87a and the second vibration surface 87b are parallel to each other. The oscillator 85 is configured to vibrate along the direction normal to the first vibration surface 87a and the direction normal to the second vibration surface 87b.

[0029] The first vibrating surface 87a of the transducer 85 is in contact with the first side end face 303c. The transducer 85 is mounted on the first side end face 303c so as to vibrate along the direction normal to the first side end face 303c. This increases the sound pressure of the sound emitted from the transparent film 30. The second vibrating surface 87b of the transducer 85 is in contact with the second side end face 303d. The transducer 85 is mounted on the second side end face 303d so as to vibrate along the direction normal to the second side end face 303d.

[0030] Here, as shown in Figure 5, when the transducer 85 vibrates along the normal direction N1 of the first main surface 301 and the second main surface 302, the vibration wave W from the transducer 85 propagates as a transverse wave TW from one side end (e.g., the first side end 30c) to the other side end (e.g., the second side end 30d). That is, the direction in which the vibration wave W propagates from the first side end 30c to the second side end 30d does not coincide with the vibration direction of the transducer 85. In this case, as shown by arrow A1 in Figure 5, the air in front of the first main surface 301 and the air in front of the second main surface 302 will vibrate only in the vicinity of the transducer 85. Note that the normal direction N1 mentioned above refers to the normal direction of the first main surface 301 and the second main surface 302 in the portion to which the transducer 85 is attached.

[0031] In contrast, in this embodiment, as shown in Figure 6, the transducer 85 is mounted on the first end face 303c such that it vibrates along the normal direction N2 of the first end face 303c. In this case, the vibration wave W1 from the transducer 85 propagates as a longitudinal wave LW along the circumferential direction from the first end face 30c to the second end face 30d. That is, the direction in which the vibration wave W1 propagates from the first end face 30c to the second end face 30d and the vibration direction of the transducer 85 are approximately the same. Also in this embodiment, the transducer 85 is mounted on the second end face 303d such that it vibrates along the normal direction N3 of the second end face 303d. In this case, the vibration wave W2 from the transducer 85 propagates as a longitudinal wave LW along the circumferential direction from the second end face 30d to the first end face 30c. In other words, the direction in which the vibration wave W2 propagates from the second end 30d to the first end 30c and the vibration direction of the transducer 85 are almost identical. In these cases, the air in front of the first main surface 301 and the air in front of the second main surface 302 vibrate over the entire area between the first end 30c and the second end 30d. That is, the air in front of the first main surface 301 and the air in front of the second main surface 302 vibrates over the entire circumference. As a result, the sound pressure of the sound emitted from the transparent film 30 can be increased. In other words, it becomes possible to generate sound accurately from the entire transparent laminated film 30, and the transparent laminated film 30 can function as a high-precision film speaker.

[0032] Furthermore, because the transducer 85 is in contact with the first end face 303c and the second end face 303d, the vibration of the transducer 85 can transmit two vibration waves, vibration wave W1 and vibration wave W2, to the transparent film 30. This effectively increases the sound pressure of the sound emitted from the transparent film 30. Also, as described above, the transparent film 30 is rolled into a tubular shape so that the first main surface 301 and the second main surface 302 are curved. Therefore, because the transducer 85 is in contact with the first end face 303c and the second end face 303d, resonance occurs inside the transparent film 30, and the sound pressure is further amplified. In the illustrated example, the transducer 85 is mounted approximately in the center in the vertical direction. However, it is not limited to this, and the transducer 85 may be mounted at any position in the vertical direction.

[0033] A voltage is applied to such a vibrator 85 through an electric wire 85a. In this embodiment, the power supply and amplifier for applying the voltage are located inside a box 95 (see Figure 1). A control unit (not shown) for controlling the vibrator is also housed inside the box 95.

[0034] Next, the structure for attaching the transducer 85 to the transparent film 30 will be described in detail. As mentioned above, the transducer 85 is attached to the first end face 303c and the second end face 303d.

[0035] As shown in Figures 7 and 8, the first side end surface 303c of the transparent film 30 may include a first contact surface 31c and a first protruding surface 32c. Of these, the first contact surface 31c is the surface that contacts the first vibration surface 87a of the vibrator 85. The first protruding surface 32c is adjacent to the first contact surface 31c and protrudes further toward the second vibration surface 87b than the first contact surface 31c. In the illustrated example, the first protruding surface 32c is located below the first contact surface 31c and protrudes outward from the first contact surface 31c. A step may be formed between the first contact surface 31c and the first protruding surface 32c. That is, the first contact surface 31c and the first protruding surface 32c may be connected to each other via a first stepped surface 33c that extends horizontally. Note that "outside" refers to the side away from the center of the first main surface 301 of the transparent film 30.

[0036] Furthermore, the first side end face 303c is located on the opposite side from the first protruding surface 32c when viewed from the first contact surface 31c, and may also include a first recessed surface 34c that is recessed on the opposite side from the second contact surface 31d, which will be described later, from the first contact surface 31c. In the illustrated example, the first recessed surface 34c is located above the first contact surface 31c and is recessed inward from the first contact surface 31c. A step may be formed between the first contact surface 31c and the first recessed surface 34c. That is, the first contact surface 31c and the first recessed surface 34c may be connected to each other via a second stepped surface 35c that extends horizontally. The "inside" refers to the side that approaches the center of the first main surface 301 of the transparent film 30.

[0037] Furthermore, as shown in Figures 7 and 8, the second side end face 303d of the transparent film 30 may include a second contact surface 31d and a second protruding surface 32d. Of these, the second contact surface 31d is the surface that contacts the second vibration surface 87b of the vibrator 85. The second protruding surface 32d is adjacent to the second contact surface 31d and protrudes further toward the first vibration surface 87a than the second contact surface 31d. In the illustrated example, the second protruding surface 32d is located below the second contact surface 31d and protrudes outward from the second contact surface 31d. A step may be formed between the second contact surface 31d and the second protruding surface 32d. That is, the second contact surface 31d and the second protruding surface 32d may be connected to each other via a third stepped surface 33d that extends horizontally.

[0038] Furthermore, the second side end face 303d may also include a second recessed surface 34d that is located on the opposite side from the second protruding surface 32d when viewed from the second contact surface 31d, and is recessed on the opposite side from the first contact surface 31c from the second contact surface 31d. In the illustrated example, the second recessed surface 34d is located above the second contact surface 31d and is recessed inward from the second contact surface 31d. A step may be formed between the second contact surface 31d and the second recessed surface 34d. That is, the second contact surface 31d and the second recessed surface 34d may be connected to each other via a fourth stepped surface 35d that extends horizontally.

[0039] When attaching the transducer 85 to the transparent film 30, first, as shown in Figure 9, the transducer 85 is sandwiched between the first contact surface 31c of the first end face 303c and the second contact surface 31d of the second end face 303d. Then, as shown in Figure 10, the transparent film 30 and the transducer 85 are sandwiched between a pair of protective members 90, and the protective members 90 are fixed to the transparent film 30 with fixing members 91 such as bolts and nuts. In this way, the transducer 85 is attached to the transparent film 30. The protective members 90 have recesses 92 that correspond to the shape of the transducer 85, so that the vibration of the transducer 85 is not hindered even after it has been attached to the transparent film 30.

[0040] In such a transparent film 30, when the vibrator 85 is sandwiched between the first contact surface 31c and the second contact surface 31d, the vibrator 85 is supported by the first stepped surface 33c and the third stepped surface 33d, as shown in Figure 9. Therefore, the vibrator 85 can be easily fixed in place.

[0041] Furthermore, the transparent film 30 has a first protruding surface 32c below the first contact surface 31c. Similarly, a second protruding surface 32d is provided below the second contact surface 31d. As a result, an overlapping region 36 is formed below the first contact surface 31c and below the second contact surface 31d where the transparent films 30 overlap. In this case, as shown in Figure 9, the fixing member 91 penetrates the overlapping region 36, thereby improving the shape retention and self-supporting ability of the transparent film 30.

[0042] Furthermore, the transparent film 30 is provided with a first recessed surface 34c above the first contact surface 31c and a second recessed surface 34d above the second contact surface 31d. As a result, as shown in Figures 9 and 10, an opening 37 is formed above the vibrator 85. Therefore, the electric wire 85a can be passed through the opening 37 to a desired position, and the box 95 can be positioned at a desired location.

[0043] As shown in Figure 11, the transducer 85 may be attached to the transparent film 30 by means of, for example, a tape 93. In this case, as shown in Figure 12, a first inwardly recessed notch 38c may be formed on the first end face 303c, and a second inwardly recessed notch 38d may be formed on the second end face 303d. The first notch 38c and the second notch 38d may form a housing portion 38 for housing the transducer 85. The tape 93 may also be used to join the transparent films 30 together. As shown in Figure 13, an uneven portion 39c may be formed on the first end face 303c, and an uneven portion 39d corresponding to the uneven portion 39c may be formed on the second end face 303d. In this case, the transparent films 30 may be joined together by fitting the uneven portions 39c and 39d together. In the illustrated example, the irregularities of the protrusions 39c and 39d are trapezoidal, but are not limited to this. The irregularities of the protrusions 39c and 39d can be any shape as long as they allow the transparent films 30 to be joined together. They may also be any shape. In addition, although not shown in the illustration, the transducer 85 may be attached to the transparent film 30, for example, with an adhesive.

[0044] Furthermore, as shown in Figure 14, the transducer 85 may be attached to the transparent film 30 using angle brackets 94. In this case, for example, four L-shaped angle brackets 94 may be prepared and the transducer 85 may be attached to the transparent film 30 by fixing adjacent angle brackets 94 with tape 93 or the like.

[0045] (Transparent laminated film) Next, the details of the transparent laminated film 30 will be described. As described above, the transparent laminated film 30 is used as a component of the sound device 10. The transparent laminated film 30 may have a protective film attached to protect the first main surface 301 or the second main surface 302. In this embodiment, a transparent laminated film 60 with a protective film attached to the transparent laminated film 30 will be described, but of course, the transparent laminated film 30 without a protective film can also be used as is. Figures 15A to 15F show an example of the layer configuration of the transparent laminated film 60 with a protective film. As shown in Figures 15A to 15F, the transparent laminated film 60 with a protective film comprises the transparent laminated film 30 according to this embodiment, a first protective film 61 that protects the first main surface 301 of the transparent laminated film 30, and a second protective film 62 that protects the second main surface 302 of the transparent laminated film 30.

[0046] The first protective film 61 and the second protective film 62 each serve to prevent scratches on the first main surface 301 and the second main surface 302 of the transparent laminated film 30, and to prevent contamination of the first main surface 301 and the second main surface 302 by foreign matter, etc. The first protective film 61 and the second protective film 62 are each detachably attached to the transparent laminated film 30. The first protective film 61 and the second protective film 62 each include a bonding layer (not shown), and may be attached to the transparent laminated film 30 by this bonding layer. The adhesive strength of the bonding layer may be, for example, 0.05 N / 25 mm or more and 5 N / 25 mm or less. When using the sound device 10 described above, the first protective film 61 and the second protective film 62 are each peeled off from the transparent laminated film 30. The material of the first protective film 61 and the second protective film 62 may be, for example, a film made of polyester resin or polyolefin such as polyethylene or polypropylene.

[0047] Next, the layer structure of the transparent laminated film 30 according to this embodiment will be described. As shown in Figures 15A to 15F, the transparent laminated film 30 includes a first anti-reflective layer 40 that constitutes the first main surface 301 and a second anti-reflective layer 50 that constitutes the second main surface 302. Furthermore, as shown in Figures 15A and 15B, the transparent laminated film 30 may further include a transparent adhesive layer 31 that adheres the first anti-reflective layer 40 and the second anti-reflective layer 50 to each other.

[0048] Specifically, as shown in Figures 15A and 15B, the transparent laminated film 30 has a first anti-reflective layer 40, a transparent adhesive layer 31, and a second anti-reflective layer 50 arranged in this order from the first main surface 301 to the second main surface 302. In this case, the first anti-reflective layer 40 of the transparent laminated film 30 is exposed outward from the first main surface 301 side. Also, the second anti-reflective layer 50 of the transparent laminated film 30 is exposed outward from the second main surface 302 side.

[0049] Furthermore, in the example shown in Figures 15A and 15B, the first anti-reflective layer 40 includes a first anti-reflective functional layer 41 arranged sequentially from the first main surface 301 toward the second main surface 302, and a first transparent substrate layer 42. The first anti-reflective functional layer 41 includes a first refractive layer 43 arranged sequentially from the first main surface 301 toward the second main surface 302, and a first hard coat layer 44. The first refractive layer 43 also includes a first low refractive index layer 45 and a first high refractive index layer 46, arranged sequentially from the first main surface 301 toward the second main surface 302. Here, the first high refractive index layer 46 may include a first high refractive index layer 47 and a second high refractive index layer 48, arranged sequentially from the first main surface 301 toward the second main surface 302, as shown in Figure 15B.

[0050] Furthermore, in the example shown in Figures 15A and 15B, the second anti-reflective layer 50 includes a second anti-reflective functional layer 51 arranged sequentially from the second main surface 302 toward the first main surface 301, and a second transparent substrate layer 52. The second anti-reflective functional layer 51 also includes a second refractive layer 53 arranged sequentially from the second main surface 302 toward the first main surface 301, and a second hard coat layer 54. The second refractive layer 53 also includes a second low refractive index layer 55 and a second high refractive index layer 56, arranged sequentially from the second main surface 302 toward the first main surface 301. Here, as shown in Figure 15B, the second high refractive index layer 56 may include a first second high refractive index layer 57 and a second second high refractive index layer 58, arranged sequentially from the second main surface 302 toward the first main surface 301.

[0051] Furthermore, as shown in Figures 15C and 15D, the transparent laminated film 30 may further include a core layer 32 located between the first anti-reflective layer 40 and the second anti-reflective layer 50. In this case, the transparent laminated film 30 may further include a first transparent adhesive layer 31a that bonds the first anti-reflective layer 40 and the core layer 32 to each other, and a second transparent adhesive layer 31b that bonds the core layer 32 and the second anti-reflective layer 50 to each other.

[0052] Specifically, as shown in Figures 15C and 15D, the transparent laminated film 30 is provided with the following layers in this order, from the first main surface 301 to the second main surface 302: the first anti-reflective layer 40, the first transparent adhesive layer 31a, the core layer 32, the second transparent adhesive layer 31b, and the second anti-reflective layer 50. In this case as well, the first anti-reflective layer 40 of the transparent laminated film 30 is exposed outward from the first main surface 301 side. Also, the second anti-reflective layer 50 of the transparent laminated film 30 is exposed outward from the second main surface 302 side.

[0053] Furthermore, in the examples shown in Figures 15C and 15D, the first anti-reflective layer 40 includes a first anti-reflective functional layer 41 arranged sequentially from the first main surface 301 toward the second main surface 302, and a first transparent substrate layer 42. The first anti-reflective functional layer 41 includes a first refractive layer 43 arranged sequentially from the first main surface 301 toward the second main surface 302, and a first hard coat layer 44. The first refractive layer 43 includes a first low refractive index layer 45 and a first high refractive index layer 46 arranged sequentially from the first main surface 301 toward the second main surface 302. Here, the first high refractive index layer 46 may include a first high refractive index layer 47 and a second high refractive index layer 48 arranged sequentially from the first main surface 301 toward the second main surface 302, as shown in Figure 15D.

[0054] Furthermore, in the examples shown in Figures 15C and 15D, the second anti-reflective layer 50 includes a second anti-reflective functional layer 51 arranged sequentially from the second main surface 302 toward the first main surface 301, and a second transparent substrate layer 52. The second anti-reflective functional layer 51 includes a second refractive layer 53 arranged sequentially from the second main surface 302 toward the first main surface 301, and a second hard coat layer 54. The second refractive layer 53 also includes a second low refractive index layer 55 and a second high refractive index layer 56, arranged sequentially from the second main surface 302 toward the first main surface 301. Here, as shown in Figure 15D, the second high refractive index layer 56 may include a first second high refractive index layer 57 and a second second high refractive index layer 58, arranged sequentially from the second main surface 302 toward the first main surface 301.

[0055] As described above, in the examples shown in Figures 15A to 15D, the first anti-reflective layer 40 has a basic configuration having a first high refractive index layer 46 and a first low refractive index layer 45 on a first transparent substrate layer 42. Also, as described above, the second anti-reflective layer 50 has a basic configuration having a second high refractive index layer 56 and a second low refractive index layer 55 on a second transparent substrate layer 52. The first high refractive index layer 46 (second high refractive index layer 56) and the first low refractive index layer 45 (second low refractive index layer 55) play a role in providing an anti-reflective function through optical interference.

[0056] The first anti-reflective layer 40 (second anti-reflective layer 50) may be further provided with an anti-reflective function through optical interference of three or more layers, such as by adding a medium refractive index layer. However, an excessively multilayer structure is undesirable from a cost-effectiveness standpoint. Therefore, in this embodiment, the first anti-reflective layer 40 (second anti-reflective layer 50) is preferably configured to provide an anti-reflective function through optical interference using two layers: a first high refractive index layer 46 (second high refractive index layer 56) and a first low refractive index layer 45 (second low refractive index layer 55). Alternatively, the first anti-reflective layer 40 (second anti-reflective layer 50) may be configured by making the first hard coat layer 44 (second hard coat layer 54) a medium refractive index layer, and providing an anti-reflective function through optical interference using three layers: a medium refractive index layer, a high refractive index layer, and a low refractive index layer.

[0057] Furthermore, as shown in Figures 15E and 15F, the first refractive layer 43 does not necessarily have to include the first high refractive index layer 46. Also, as shown in Figures 15E and 15F, the second refractive layer 53 does not necessarily have to include the second high refractive index layer 56.

[0058] The following describes each layer of the transparent laminated film 30.

[0059] <First anti-reflective layer and second anti-reflective layer> The first anti-reflective layer 40 is a layer for suppressing the reflection of light incident on the first main surface 301 side of the transparent laminated film 30. Because the transparent laminated film 30 is equipped with the first anti-reflective layer 40, the reflection of light on the first main surface 301 of the transparent laminated film 30 can be suppressed. This improves the visibility of the contents (exhibits) when a user on the second main surface 302 side (the outside side of the sound device 10) of the transparent laminated film 30 views the contents (exhibits) displayed on the first main surface 301 side (the inside side of the sound device 10). More specifically, it prevents the user's own face or other reflections from being visible on the first main surface 301 of the transparent laminated film 30 when viewing the contents. This reduces the difficulty in viewing the contents from the user. Furthermore, it reduces the likelihood of the user experiencing discomfort or fatigue due to light reflected on the first main surface 301 of the transparent laminated film 30.

[0060] On the other hand, the second anti-reflective layer 50 is a layer for suppressing the reflection of light incident from the second main surface 302 side of the transparent laminated film 30. Because the transparent laminated film 30 is equipped with the second anti-reflective layer 50, the reflection of light on the second main surface 302 of the transparent laminated film 30 can be suppressed. In this case as well, for example, when a user who is on the second main surface 302 side of the transparent laminated film 30 (the outside side of the sound device 10) views the contents (exhibits) displayed on the first main surface 301 side of the transparent laminated film 30 (the inside side of the sound device 10), the visibility of the contents can be improved. More specifically, when a user views the contents, it is possible to suppress the reflection of the user's own face or other images on the second main surface 302 of the transparent laminated film 30. This prevents the contents from becoming difficult to see for the user. In addition, it is possible to suppress the user from experiencing discomfort or fatigue due to the light reflected on the second main surface 302 of the transparent laminated film 30. As described above, since both the first anti-reflective layer 40 and the second anti-reflective layer 50 consist of layers for suppressing reflection, a transparent laminated film 30 having such a first anti-reflective layer 40 and second anti-reflective layer 50 can also be called a low-reflection transparent laminated film.

[0061] As described above, the first anti-reflective layer 40 has a first anti-reflective functional layer 41 and a first transparent substrate layer 42. Similarly, as described above, the second anti-reflective layer 50 has a second anti-reflective functional layer 51 and a second transparent substrate layer 52. Here, we will first describe the first transparent substrate layer 42 and the second transparent substrate layer 52.

[0062] [First transparent substrate layer and second transparent substrate layer] The first transparent substrate layer 42 and the second transparent substrate layer 52 are layers that support, for example, the first anti-reflective functional layer 41 and the second anti-reflective functional layer 51, and also increase the overall strength of the first anti-reflective layer 40 and the second anti-reflective layer 50. The material of the first transparent substrate layer 42 and the second transparent substrate layer 52 is not particularly limited as long as it is a transparent material used as a substrate for general films, but from the viewpoint of material cost, productivity, etc., plastic films, plastic sheets, etc. can be appropriately selected depending on the application.

[0063] Materials for plastic films or plastic sheets include materials made from various synthetic resins. Preferred synthetic resins include cellulose resins such as triacetylcellulose resin (TAC), diacetylcellulose, acetate butyrate cellulose, and cellophane; polyester resins such as polyethylene terephthalate resin (PET), polybutylene terephthalate resin, polyethylene naphthalate-isophthalate copolymer resin, and polyester thermoplastic elastomers; polyolefin resins such as low-density polyethylene resin (including linear low-density polyethylene resin), medium-density polyethylene resin, high-density polyethylene resin, ethylene α-olefin copolymer, polypropylene resin, polymethylpentene resin, polybutene resin, ethylene-propylene copolymer, propylene-butene copolymer, olefin thermoplastic elastomers, or mixtures thereof; acrylic resins such as poly(meth)acrylate methyl resin, poly(meth)acrylate ethyl resin, and poly(meth)acrylate butyl resin; polyamide resins represented by nylon 6 or nylon 66; polystyrene resin; polycarbonate resin; polyarylate resin; or polyimide resin. Furthermore, the materials of the first transparent substrate layer 42 and the second transparent substrate layer 52 may be cycloolefin polymer (COP) resins or cycloolefin copolymer (COC) resins.

[0064] The first transparent substrate layer 42 and the second transparent substrate layer 52 can be selected individually from the above-mentioned plastic films and plastic sheets, or as a mixture of two or more. However, from the viewpoint of flexibility, toughness, and transparency, cellulose resin and polyester resin are more preferred as the materials for the first transparent substrate layer 42 and the second transparent substrate layer 52. Furthermore, from the viewpoint of flexibility, toughness, and transparency, it is preferable that the first transparent substrate layer 42 and the second transparent substrate layer 52 contain triacetylcellulose and polyethylene terephthalate.

[0065] There are no particular restrictions on the thickness of the first transparent substrate layer 42 and the second transparent substrate layer 52, and they can be appropriately selected according to the application. The thickness of the first transparent substrate layer 42 and the second transparent substrate layer 52 may be approximately 5 μm to 130 μm, but considering durability and handling, it is preferable that they be 10 μm to 100 μm. The thickness of each layer can be calculated, for example, by measuring the thickness at three points on a cross-sectional image taken using a scanning electron microscope (SEM) or scanning transmission electron microscope (STEM), and averaging the values ​​of the three points. When the film thickness to be measured is on the order of μm, it is preferable to use SEM, and when it is on the order of nm, it is preferable to use STEM. In the case of SEM, it is preferable that the acceleration voltage be 1 kV to 10 kV, and in the case of STEM, it is preferable that the acceleration voltage be 10 kV to 30 kV. The film thickness of each layer described below can be measured in the same way as the film thickness of the first transparent substrate layer 42 and the second transparent substrate layer 52.

[0066] [First anti-reflective layer and second anti-reflective layer] Next, the first anti-reflective layer 41 and the second anti-reflective layer 51 will be described. The first anti-reflective layer 41 and the second anti-reflective layer 51 each play a role in providing the first anti-reflective layer 40 and the second anti-reflective layer 50 with the function of suppressing light reflection.

[0067] Furthermore, the first anti-reflective functional layer 41 may be a coating layer coated on the first transparent substrate layer 42, and the second anti-reflective functional layer 51 may be a coating layer coated on the second transparent substrate layer 52. In this way, by having the first anti-reflective functional layer 41 and the second anti-reflective functional layer 51 be coating layers, the thickness of the first anti-reflective functional layer 41 and the second anti-reflective functional layer 51 can be easily controlled, and desired functions such as the light reflectance and total light transmittance of the transparent laminated film 30 can be easily controlled.

[0068] Preferably, the first anti-reflective functional layer 41 and the second anti-reflective functional layer 51 are made of a cured product containing an acrylic monomer. This makes it possible to form the first anti-reflective functional layer 41 and the second anti-reflective functional layer 51 with high uniformity even with short processing time.

[0069] Here, the first anti-reflective functional layer 41 includes a first refractive layer 43 and a first hard coat layer 44, as described above. The second anti-reflective functional layer 51 also includes a second refractive layer 53 and a second hard coat layer 54, as described above. The first hard coat layer 44 may be a coating layer coated on the first transparent substrate layer 42, and the first refractive layer 43 may be a coating layer coated on the first hard coat layer 44. The second hard coat layer 54 may be a coating layer coated on the second transparent substrate layer 52, and the second refractive layer 53 may be a coating layer coated on the second hard coat layer 54. In this way, because the first refractive layer 43, the first hard coat layer 44, the second refractive layer 53 and the second hard coat layer 54 are coating layers, the thickness of each layer can be easily controlled, and desired functions such as the light reflectance, total light transmittance, and, in some cases, color of the transparent laminated film 30 can be easily controlled.

[0070] Next, the first hard coat layer 44 and the second hard coat layer 54 will be described.

[0071] {First hard coat layer and second hard coat layer} The first hard coat layer 44 and the second hard coat layer 54 play a role in improving the scratch resistance of the first anti-reflective layer 40 and the second anti-reflective layer 50. Here, "hard coat" refers to a property that exhibits a hardness of "H" or higher in the pencil hardness test specified in JIS K5600-5-4:1999. The first hard coat layer 44 and the second hard coat layer 54 can be formed, for example, from a hard coat layer coating liquid containing a curable resin composition. Examples of curable resin compositions include thermosetting resin compositions and ionizing radiation curable resin compositions, and ionizing radiation curable resin compositions are preferred from the viewpoint of scratch resistance.

[0072] A thermosetting resin composition is a composition containing at least a thermosetting resin, which hardens upon heating. Examples of thermosetting resins include acrylic resins, urethane resins, phenolic resins, urea-melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins. A curing agent is added to these curable resins as needed in the thermosetting resin composition.

[0073] Ionizing radiation-curable resin compositions are compositions containing compounds having ionizing radiation-curable functional groups (hereinafter also referred to as "ionizing radiation-curable compounds"). Examples of ionizing radiation-curable functional groups include ethylenically unsaturated bonding groups such as (meth)acryloyl groups, vinyl groups, and allyl groups, as well as epoxy groups and oxetanyl groups. As ionizing radiation-curable compounds, compounds having ethylenically unsaturated bonding groups are preferred, compounds having two or more ethylenically unsaturated bonding groups are more preferred, and among these, polyfunctional (meth)acrylate compounds having two or more ethylenically unsaturated bonding groups are even more preferred. Both monomers and oligomers can be used as polyfunctional (meth)acrylate compounds. Ionizing radiation refers to electromagnetic waves or charged particle beams that have energy quanta capable of polymerizing or crosslinking molecules, and usually ultraviolet (UV) or electron beams (EB) are used, but other electromagnetic waves such as X-rays and gamma rays, and charged particle beams such as alpha rays and ion beams can also be used.

[0074] Among the polyfunctional (meth)acrylate compounds, examples of bifunctional (meth)acrylate monomers include ethylene glycol di(meth)acrylate, bisphenol A tetraethoxydiacrylate, bisphenol A tetrapropoxydiacrylate, and 1,6-hexanediol diacrylate. Examples of trifunctional or more (meth)acrylate monomers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and isocyanuric acid-modified tri(meth)acrylate. Furthermore, the above (meth)acrylate monomers may also be monomers in which part of the molecular skeleton has been modified, and may be monomers modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol, etc.

[0075] Furthermore, examples of polyfunctional (meth)acrylate oligomers include acrylate polymers such as urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, and polyether (meth)acrylate. Urethane (meth)acrylate can be obtained, for example, by the reaction of polyhydric alcohols and organic diisocyanates with hydroxy(meth)acrylate. Preferred epoxy (meth)acrylates are (meth)acrylates obtained by reacting trifunctional or higher aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, etc. with (meth)acrylic acid, (meth)acrylates obtained by reacting bifunctional or higher aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, etc. with polybasic acids and (meth)acrylic acid, and (meth)acrylates obtained by reacting bifunctional or higher aromatic epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, etc. with phenols and (meth)acrylic acid. The above ionizing radiation-curable compounds can be used individually or in combination of two or more.

[0076] When the ionizing radiation-curable compound is an ultraviolet-curable compound, the ionizing radiation-curable composition preferably contains additives such as photopolymerization initiators and photopolymerization accelerators. Examples of photopolymerization initiators include one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler ketone, benzoin, benzyl methyl ketal, benzoyl benzoate, α-acyloxime esters, thioxanthones, etc. These photopolymerization initiators preferably have a melting point of 100°C or higher. By setting the melting point of the photopolymerization initiator to 100°C or higher, it is possible to prevent residual photopolymerization initiator from sublimating due to the heat during transparent conductive film formation or crystallization processes, thereby preventing damage to the low resistance of the transparent conductive film. The same applies when using photopolymerization initiators in the high refractive index layer and low refractive index layer described later. Furthermore, photopolymerization accelerators are materials that reduce polymerization inhibition by air during curing and accelerate the curing speed, and examples include one or more selected from p-dimethylaminobenzoate isoamyl ester, p-dimethylaminobenzoate ethyl ester, etc.

[0077] The thickness of the first hard coat layer 44 and the second hard coat layer 54 is preferably in the range of 0.1 μm to 100 μm, and more preferably in the range of 0.8 μm to 20 μm. If the thickness of the first hard coat layer 44 and the second hard coat layer 54 are within the above range, sufficient hard coat performance can be obtained, and the surface will be less prone to cracking and other damage from external impacts.

[0078] The refractive indices of the first hard coat layer 44 and the second hard coat layer 54 are preferably smaller than those of the first high refractive index layer 46 and the second high refractive index layer 56, more preferably between 1.45 and 1.70, and even more preferably between 1.45 and 1.60. When the refractive indices of the first hard coat layer 44 and the second hard coat layer 54 are within this range, the first hard coat layer 44 and the second hard coat layer 54 each function as a medium refractive index layer. This enables interference between the three layers of the first hard coat layer 44, the first high refractive index layer 46, and the first low refractive index layer 45, and interference between the three layers of the second hard coat layer 54, the second high refractive index layer 56, and the second low refractive index layer 55. Therefore, light reflection can be effectively suppressed. Furthermore, from the viewpoint of suppressing interference fringes, it is preferable to reduce the difference between the refractive indices of the first hard coat layer 44 and the second hard coat layer 54 and the refractive indices of the first transparent substrate layer 42 and the second transparent substrate layer 52.

[0079] Means for imparting the role of a medium refractive index layer to the first hard coat layer 44 and the second hard coat layer 54 include blending a resin with a high refractive index into the hard coat layer coating liquid and blending particles with a high refractive index. When particles with a high refractive index are blended, whitening or coating defects may occur due to aggregation of the particles, so the former method (blending a resin with a high refractive index) is preferred. Examples of resins with a high refractive index include the thermosetting resin or ionizing radiation-curable compound described above, into which groups containing sulfur, phosphorus, or bromine, or aromatic rings, etc., are introduced. As for particles with a high refractive index, the same particles as the high refractive index particles used in the first high refractive index layer 46 and the second high refractive index layer 56 described later can be used.

[0080] The refractive indices of each layer, such as the first hard coat layer 44 and the second hard coat layer 54, can be calculated, for example, by fitting the reflection spectrum measured by a reflectance photometer with the reflection spectrum calculated from an optical model of a multilayer thin film using Fresnel coefficients.

[0081] The first hard coat layer 44 and the second hard coat layer 54 can be formed by preparing a coating solution for hard coat layer formation using the above-mentioned curable resin composition, additives such as ultraviolet absorbers and leveling agents as needed, and a diluent, applying the coating solution onto a transparent substrate using a conventionally known coating method, drying it, and curing it by irradiating it with ionizing radiation as needed.

[0082] {First refractive layer and second refractive layer} Next, the first refractive layer 43 and the second refractive layer 53 will be described. The first refractive layer 43 and the second refractive layer 53 play a role in reducing the light reflectivity of the first anti-reflective layer 40 and the second anti-reflective layer 50. As described above, the first refractive layer 43 includes a first low refractive index layer 45 and a first high refractive index layer 46. The second refractive layer 53 also includes a second low refractive index layer 55 and a second high refractive index layer 56. Here, we will first describe the first low refractive index layer 45 and the second low refractive index layer 55.

[0083] (First low refractive index layer and second low refractive index layer) The first low refractive index layer 45 and the second low refractive index layer 55 are layers provided on the first high refractive index layer 46 and the second high refractive index layer 56, and play a role in reducing the light reflectivity of the first anti-reflective layer 40 and the second anti-reflective layer 50 by interference using the difference in refractive index between them and the first high refractive index layer 46 and the second high refractive index layer 56. In order to make the first anti-reflective layer 40 and the second anti-reflective layer 50 ultra-low reflectivity, the refractive index of the first low refractive index layer 45 and the second low refractive index layer 55 is preferably 1.26 or more and 1.40 or less, more preferably 1.28 or more and 1.38 or less, and even more preferably 1.30 or more and 1.32 or less. The lower the refractive index of the first low refractive index layer 45 and the second low refractive index layer 55, the lower the refractive index of the first anti-reflective layer 40 and the second anti-reflective layer 50 can be without having to raise the refractive index of the first high refractive index layer 46 and the second high refractive index layer 56 as much. On the other hand, if the refractive indices of the first low refractive index layer 45 and the second low refractive index layer 55 are made too low, the strength of the first low refractive index layer 45 and the second low refractive index layer 55 tends to decrease. For this reason, by setting the refractive indices of the first low refractive index layer 45 and the second low refractive index layer 55 within the above range, it is possible to maintain the strength of the first low refractive index layer 45 and the second low refractive index layer 55 while suppressing the amount of high refractive index particles added to the first high refractive index layer 46 and the second high refractive index layer 56, which is preferable in that it leads to the suppression of discoloration and whitening. Furthermore, the thickness of the first low refractive index layer 45 and the second low refractive index layer 55 is preferably 80 nm to 120 nm, more preferably 85 nm to 110 nm, and even more preferably 90 nm to 105 nm. In addition, the first low refractive index layer 45 and the second low refractive index layer 55 may be formed from multiple layers that satisfy the above refractive index range, but from the viewpoint of cost-effectiveness, two layers or less are preferred, and a single layer is more preferred.

[0084] Methods for forming the first low refractive index layer 45 and the second low refractive index layer 55 can be broadly classified into wet methods and dry methods. Wet methods include forming the layers by a sol-gel method using metal alkoxides, forming the layers by coating with a low refractive index resin such as fluororesin, and forming the layers by coating with a coating solution for forming low refractive index layers that contains low refractive index particles in a resin composition. Dry methods include selecting particles with a desired refractive index from the low refractive index particles described later and forming the layers by physical vapor deposition or chemical vapor deposition. Wet methods are superior in terms of production efficiency, and in this embodiment, among wet methods, it is preferable to form the layers using a coating solution for forming low refractive index layers that contains low refractive index particles in a resin composition.

[0085] Low refractive index particles are preferably used to lower their refractive index, that is, to improve anti-reflective properties. They can be inorganic, such as silica or magnesium fluoride, or organic, without limitation. However, from the viewpoint of further improving anti-reflective properties and ensuring good surface hardness, particles with a void structure are preferably used.

[0086] Particles having a structure that contains voids have fine voids inside, and are filled with gases such as air with a refractive index of 1.0, resulting in particles with a low refractive index of their own. Examples of such void-containing particles include inorganic or organic porous particles and hollow particles, such as porous silica, hollow silica particles, or porous polymer particles and hollow polymer particles using acrylic resin. As an inorganic particle, silica particles with voids prepared using the technology disclosed in Japanese Patent Application Publication No. 2001-233611 are a preferred example. As an organic particle, hollow polymer particles prepared using the technology disclosed in Japanese Patent Application Publication No. 2002-80503 are a preferred example. The above-mentioned silica with voids or porous silica have a refractive index in the range of 1.18 to 1.44, which is lower than that of general silica particles with a refractive index of about 1.45, and is therefore preferred from the viewpoint of lowering the refractive index of the first low refractive index layer 45 and the second low refractive index layer 55.

[0087] Hollow silica particles are particles that have the function of lowering the refractive index while maintaining the coating strength of the first low refractive index layer 45 and the second low refractive index layer 55. The hollow silica particles used in this embodiment are silica particles with a structure having a cavity inside. Hollow silica particles are silica particles in which the refractive index decreases inversely proportional to the occupancy rate of the internal cavity compared to the original refractive index of the silica particle (refractive index n = approximately 1.45). For this reason, the refractive index of the hollow silica particles as a whole is between 1.18 and 1.44.

[0088] The hollow silica particles are not particularly limited, and examples include particles having an outer shell and having a porous or hollow interior, such as silica particles prepared using the techniques disclosed in Japanese Patent Publication No. 6-330606, Japanese Patent Publication No. 7-013137, Japanese Patent Publication No. 7-133105, and Japanese Patent Publication No. 2001-233611.

[0089] The average particle diameter of the primary particles of the low refractive index particles is preferably 5 nm to 200 nm, more preferably 5 nm to 100 nm, and even more preferably 10 nm to 80 nm. If the average particle diameter of the primary particles is within the above range, the transparency of the first low refractive index layer 45 and the second low refractive index layer 55 is not impaired, and a good particle dispersion state can be obtained. In particular, hollow particles are used as the low refractive index particles, and the average particle diameter of these hollow particles is 70 nm to 80 nm, which is preferable because it can increase the porosity and lower the refractive index while maintaining an outer shell thickness that does not result in insufficient strength, and it also has an excellent balance with the ideal thickness (approximately 100 nm) of the first low refractive index layer 45 and the second low refractive index layer 55 for lowering the reflectivity.

[0090] In this embodiment, the low refractive index particles used are preferably surface-treated particles. As the surface treatment of the low refractive index particles, surface treatment using a silane coupling agent is more preferable, and among these, surface treatment using a silane coupling agent having a (meth)acryloyl group is preferable. By surface-treating the low refractive index particles, the affinity with the binder resin described later is improved, the dispersion of particles becomes uniform, and aggregation of particles is less likely to occur. As a result, the decrease in transparency of the first low refractive index layer 45 and the second low refractive index layer 55 due to the formation of larger particles due to aggregation, as well as the decrease in the applicability of the layer-forming composition and the decrease in the coating strength of the composition, are suppressed.

[0091] Furthermore, if the silane coupling agent has a (meth)acryloyl group, the silane coupling agent is ionizing radiation curable and therefore readily reacts with the binder resin described later, so that the low refractive index particles are well fixed to the binder resin in the coating film of the layer-forming composition. In other words, the low refractive index particles function as a crosslinking agent in the binder resin. This provides a tightening effect on the entire coating film, making it possible to impart excellent surface hardness to the first low refractive index layer 45 and the second low refractive index layer 55 while retaining the inherent flexibility of the binder resin. Consequently, the first low refractive index layer 45 and the second low refractive index layer 55 deform by utilizing their own flexibility, thus possessing shock absorption and restorative properties, which suppresses the occurrence of scratches and results in layers with high surface hardness and excellent scratch resistance.

[0092] Examples of silane coupling agents that are preferably used in the surface treatment of low refractive index particles include 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, 2-(meth)acryloxypropyltrimethoxysilane, and 2-(meth)acryloxypropyltriethoxysilane.

[0093] The content of low refractive index particles in the first low refractive index layer 45 and the second low refractive index layer 55 is preferably 10 parts by mass or more and 250 parts by mass or less, more preferably 50 parts by mass or more and 200 parts by mass or less, and even more preferably 100 parts by mass or more and 180 parts by mass or less, per 100 parts by mass of resin in the first low refractive index layer 45 and the second low refractive index layer 55, respectively. If the content of low refractive index particles is within the above range, good anti-reflective properties and surface hardness can be obtained. Furthermore, the proportion of hollow particles and / or porous particles in the total low refractive index particles contained in the first low refractive index layer 45 and the second low refractive index layer 55 is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 80% by mass or more and 95% by mass or less, respectively.

[0094] As resin compositions included in the layer-forming coating liquid, curable resin compositions are the first to be mentioned. As curable resin compositions, materials similar to those exemplified in the description of the first hard coat layer 44 and the second hard coat layer 54 can be used, and ionizing radiation-curable resin compositions are preferred. Furthermore, fluorine-containing polymers and fluorine monomers that themselves exhibit a low refractive index are also preferably used as resin compositions. Fluorine-containing polymers are polymers of polymerizable compounds that contain at least a fluorine atom in their molecules, and are preferred in that they can impart antifouling and slipperiness. It is preferable that the fluorine-containing polymer is a polymer that has a reactive group in its molecule and functions as a curable resin composition, and it is more preferable that it is a polymer that has an ionizing radiation-curable reactive group and functions as an ionizing radiation-curable resin composition.

[0095] As a fluorine-containing polymer, it is preferable that the polymer contains silicon along with fluorine in order to not only repel dirt on the surface of the low refractive index layer but also to provide the ability to wipe away the repelled dirt. For example, a silicone-containing vinylidene fluoride copolymer, in which a silicone component is contained in the copolymer, is preferred. In this case, examples of silicone components include (poly)dimethylsiloxane, (poly)diethylsiloxane, (poly)diphenylsiloxane, (poly)methylphenylsiloxane, alkyl-modified (poly)dimethylsiloxane, azo group-containing (poly)dimethylsiloxane, dimethyl silicone, phenylmethyl silicone, alkyl / aralkyl-modified silicone, fluorosilicone, polyether-modified silicone, fatty acid ester-modified silicone, methyl hydrogen silicone, silanol group-containing silicone, alkoxy group-containing silicone, phenol group-containing silicone, methacrylic-modified silicone, acrylic-modified silicone, amino-modified silicone, carboxylic acid-modified silicone, carbinol-modified silicone, epoxy-modified silicone, mercapto-modified silicone, fluorine-modified silicone, and polyether-modified silicone. Among these, a component having a dimethylsiloxane structure is preferred as the silicone component.

[0096] The first low refractive index layer 45 and the second low refractive index layer 55 can be formed, for example, by preparing a layer-forming coating solution using low refractive index particles, a resin composition, additives such as ultraviolet absorbers and leveling agents as needed, and a diluent, and then applying the coating solution onto the first high refractive index layer 46 or the second high refractive index layer 56 by a conventionally known coating method, drying, and curing by irradiation with ionizing radiation as needed.

[0097] (First high refractive index layer and second high refractive index layer) The first high refractive index layer 46 and the second high refractive index layer 56 play a role in reducing the light reflectivity of the first anti-reflective layer 40 and the second anti-reflective layer 50 by interference, using the difference in refractive index between them and the first low refractive index layer 45 and the second low refractive index layer 55. The first high refractive index layer 46 and the second high refractive index layer 56 can be formed, for example, from a curable resin composition and a layer-forming coating liquid containing high refractive index particles, respectively.

[0098] From the viewpoint of achieving ultra-low reflectivity of the first anti-reflection layer 40 and the second anti-reflection layer 56, it is preferable to have a high refractive index. However, increasing the refractive index requires a large amount of high refractive index particles, which can lead to aggregation of high refractive index particles and cause whitening. For this reason, the refractive index is preferably 1.55 or more and 1.85 or less, and more preferably 1.56 or more and 1.70 or less. Furthermore, the thickness of the first high refractive index layer 46 and the second high refractive index layer 56 is preferably 200 nm or less, and more preferably 50 nm or more and 180 nm or less. When the first high refractive index layer 46 and the second high refractive index layer 56 each consist of a two-layer structure as described later, it is preferable that the total thickness of the two layers satisfies the above value. In addition, the first high refractive index layer 46 and the second high refractive index layer 56 may be formed from multiple layers that satisfy the above refractive index range, but from the viewpoint of cost-effectiveness, two layers or less is preferable, and a single layer is more preferable.

[0099] Examples of high refractive index particles include antimony pentoxide (1.79), zinc oxide (1.90), titanium dioxide (2.3 to 2.7), cerium oxide (1.95), tin-doped indium oxide (1.95 to 2.00), antimond-doped tin oxide (1.75 to 1.85), yttrium oxide (1.87), and zirconium oxide (2.10). The values ​​in parentheses above indicate the refractive index of the material of each particle. Among these high refractive index particles, particles with a refractive index exceeding 2.0 are preferred from the viewpoint of achieving the above-mentioned suitable refractive index with a small amount of addition. Furthermore, conductive high refractive index particles such as antimony pentoxide, tin-doped indium oxide (ITO), and antimond-doped tin oxide (ATO) have free electrons with plasma frequencies in the near-infrared region. Due to the plasma oscillations of these free electrons, some visible light may be absorbed or reflected, making it difficult to suppress color. For this reason, it is preferable that the high refractive index particles are non-conductive particles. From the above, among the high refractive index particles exemplified above, titanium oxide and zirconium oxide are preferred, and furthermore, from the viewpoint of high durability and stability such as light resistance, zirconium oxide is optimal. If it is desired to impart antistatic properties to the first anti-reflective layer 40 and the second anti-reflective layer 50, it is preferable to have a two-layer structure for the first high refractive index layer 46 and the second high refractive index layer 56 as described later, and to include conductive high refractive index particles in one of the layers.

[0100] The average particle diameter of the primary particles of the high refractive index particles is preferably 5 nm to 200 nm, more preferably 5 nm to 100 nm, and even more preferably 10 nm to 80 nm. The average particle diameter of the primary particles of the high refractive index particles and the low refractive index particles described later can be calculated by the following steps (1) to (3).

[0101] (1) Surface images are taken of the particles themselves, or a material obtained by coating a dispersion of particles onto a transparent substrate and drying it, using SEM, TEM, or STEM.

[0102] (2) Extract any 10 particles from the surface image, measure the major and minor axes of each particle, and calculate the particle diameter of each particle from the average of the major and minor axes. The major axis is the longest axis on the screen, and the minor axis is the distance between two points where a line segment perpendicular to the midpoint of the line segment constituting the major axis intersects the particle.

[0103] (3) Perform the same procedure five times on different images of the same sample, and the average particle diameter is taken from the number average of the particle diameters of a total of 50 particles.

[0104] When calculating the average particle diameter, it is preferable to use a scanning electron microscope (SEM) if the average particle diameter to be calculated is on the order of micrometers, and it is preferable to use a transmission electron microscope (TEM) or a scanning electron microscope (STEM) if the average particle diameter to be calculated is on the order of nanometers. In the case of an SEM, the acceleration voltage is preferably 1kV to 10kV, and in the case of a TEM or STEM, the acceleration voltage is preferably 10kV to 30kV.

[0105] From the viewpoint of balancing high refractive index, color suppression, and whitening suppression, the content of high refractive index particles is preferably 30 parts by mass or more and 400 parts by mass or less, more preferably 50 parts by mass or more and 200 parts by mass or less, and even more preferably 80 parts by mass or more and 150 parts by mass or less, per 100 parts by mass of the curable resin composition.

[0106] The first high refractive index layer 46 and the second high refractive index layer 56 are preferably dispersion-stabilized to suppress excessive aggregation of high refractive index particles. One means of dispersion stabilization is to add another high refractive index particle having a lower surface charge than the base high refractive index particle. According to this means, the base high refractive index particle gathers appropriately around the other high refractive index particle, and excessive aggregation of the base high refractive index particle can be suppressed. Another means of dispersion stabilization is to use surface-treated particles as high refractive index particles or to add a dispersant to the layer-forming coating liquid.

[0107] As the curable resin composition for forming the first high refractive index layer 46 and the second high refractive index layer 56, the same materials as those exemplified in the description of the first hard coat layer 44 and the second hard coat layer 54 can be used, and an ionizing radiation curable resin composition is preferred. Furthermore, in order to obtain the above-mentioned refractive index without excessive addition of high refractive index particles, it is preferable to use a curable resin composition with a high refractive index. The refractive index of the curable resin composition is preferably 1.54 or more and 1.70 or less.

[0108] As described above, the first high refractive index layer 46 may include a first high refractive index layer 47 and a second high refractive index layer 48. In this case, it is preferable that the refractive index of the first high refractive index layer 47 is higher than that of the second high refractive index layer 48. This makes it possible to increase the refractive index difference between the first high refractive index layer 46 and the first low refractive index layer 45, thereby lowering the reflectance of the first anti-reflective layer 40, and also reduces the refractive index difference between the first high refractive index layer 46 and the first hard coat layer 44, thereby suppressing the generation of interference fringes.

[0109] Furthermore, as described above, the second high refractive index layer 56 may include the first second high refractive index layer 57 and the second second high refractive index layer 58. In this case, as with the first high refractive index layer 46, it is preferable that the refractive index of the first second high refractive index layer 57 be higher than that of the second second high refractive index layer 58. This makes it possible to increase the refractive index difference between the second high refractive index layer 56 and the second low refractive index layer 55, thereby lowering the reflectivity of the second anti-reflective layer 50, and also reduces the refractive index difference between the second high refractive index layer 56 and the second hard coat layer 54, thereby suppressing the generation of interference fringes.

[0110] Furthermore, when the first high refractive index layer 46 and the second high refractive index layer 56 are each configured as two layers, the refractive indices of the first high refractive index layer 47 and the first second high refractive index layer 57 are preferably 1.60 or more and 1.85 or less, respectively, and the refractive indices of the second high refractive index layer 48 and the second second high refractive index layer 58 are preferably 1.55 or more and 1.70 or less, respectively. Moreover, in the above two-layer configuration, it is preferable that one layer contains conductive high refractive index particles and the other layer contains non-conductive high refractive index particles, and that [thickness of the layer containing conductive high refractive index particles < thickness of the layer containing non-conductive high refractive index particles]. By adopting this configuration, antistatic properties can be provided while suppressing the amount of conductive high refractive index particles that may cause discoloration. Furthermore, by networking the conductive high refractive index particles within the layer, antistatic properties can be provided with a small amount of addition, and consequently, discoloration and whitening can be suppressed, which is preferable.

[0111] The first high refractive index layer 46 and the second high refractive index layer 56 can be formed by preparing a layer-forming coating solution using high refractive index particles, a curable resin composition, additives such as ultraviolet absorbers and leveling agents as needed, and a diluent, and then applying the coating solution onto the first hard coat layer 44 or the second hard coat layer 54 by a conventionally known coating method, drying, and curing by irradiation with ionizing radiation as needed.

[0112] [Transparent adhesive layer, first transparent adhesive layer, and second transparent adhesive layer] The transparent adhesive layers, such as the transparent adhesive layer 31, the first transparent adhesive layer 31a, and the second transparent adhesive layer 31b, are layers for bonding the first anti-reflective layer 40, the second anti-reflective layer 50, the core layer 32, and the like to each other. Here, the term "transparent adhesive layer" in this specification is a concept that includes transparent adhesive layers. Transparent adhesive layers can be formed using various materials commonly used as adhesives. Examples include acrylic adhesives, urethane adhesives, olefin adhesives, rubber adhesives, silicone adhesives, and polyester adhesives. Acrylic adhesives, which offer high transparency and high adhesive strength, are preferred.

[0113] Each of the above adhesives can contain various functionalizing agents and stabilizers, etc., within a range that does not impair transparency. Adhesion can also be enhanced by incorporating tackifiers. Furthermore, crosslinking agents such as isocyanates, epoxy compounds, and double bond-containing compounds can be used to form crosslinked structures, depending on the resin.

[0114] The transparent adhesive layer can also be formed using an adhesive (OCA, Optical Clear Adhesive) that is laminated on both sides with a release film. Commercially available products can also be used as the transparent adhesive layer. Examples of commercially available products that can be used as a transparent adhesive layer include the LUCIACS series of optical transparent adhesive sheets (manufactured by Nitto Denko Corporation), the 5400A series of highly transparent double-sided tapes (manufactured by Sekisui Chemical Co., Ltd.), the Opteria series of optical adhesive sheets (manufactured by Lintec Corporation), the SANCUARY series (manufactured by San-ei Chemical Co., Ltd.), the OAD series of optical transparent adhesives (manufactured by Toyo Packaging Co., Ltd.), the RA series of coreless double-sided tapes for optical applications (manufactured by Sumilon Co., Ltd.), and the Panaclean series PD-S1 (manufactured by Panac Co., Ltd.). The adhesive strength of these adhesives is generally 10N / 25mm or more.

[0115] The thickness of the transparent adhesive layer is not particularly limited, but is preferably, for example, 2 μm or more and 200 μm or less. If the thickness of the transparent adhesive layer is 2 μm or more, the first anti-reflective layer 40 and the second anti-reflective layer 50, etc., can be reliably bonded, and if the thickness of the transparent adhesive layer is 200 μm or less, transparency (light transmittance) can be maintained. The lower limit of the thickness of the transparent adhesive layer is more preferably 5 μm or more, 10 μm or more, or 15 μm or more, and the upper limit is more preferably 150 μm or less, 160 μm or less, or 170 μm or less.

[0116] The method for forming the transparent adhesive layer is not particularly limited, and known methods used in the manufacture of adhesive tapes and the like can be employed. Specifically, the transparent adhesive layer can be formed by any method such as coating the surface of a substrate with a paint made of an adhesive composition obtained by dissolving or dispersing each component that forms the transparent adhesive layer in a suitable organic solvent or water, and then drying and curing it; coating the substrate with each component that forms the transparent adhesive layer, double bond-containing monomers, oligomers, crosslinking agents, etc., without a solvent, and then crosslinking with radiation or the like; or by an extrusion lamination method.

[0117] When using OCA, a transparent adhesive layer can be formed by peeling off the release film on the easily peelable side of the OCA and bonding the adhesive side to the substrate.

[0118] [Core Layer] The core layer 32 serves to support the first anti-reflective layer 40 and the second anti-reflective layer 50. The core layer 32 can be made of the same material as the first transparent substrate layer 42 and the second transparent substrate layer 52 described above.

[0119] There are no particular restrictions on the thickness of the core layer 32, and it can be appropriately selected depending on the application. The thickness of the core layer 32 may be between 5 μm and 130 μm, but considering durability and handling, it is preferable that it be between 10 μm and 100 μm.

[0120] The thickness of the transparent laminated film 30 described above is preferably 500 μm or less. Here, the thinner the transparent laminated film 30, the higher the sound pressure of the sound emitted from the transparent film 30. For this reason, by having a thickness of 500 μm or less for the transparent laminated film 30, the sound pressure of the sound emitted from the transparent film 30 can be effectively increased. From the viewpoint of making conversation easier to hear, the thickness of the transparent laminated film 30 is more preferably 260 μm or less, and even more preferably 200 μm or less.

[0121] From the viewpoint of reducing the thickness of the transparent laminated film 30, a transparent laminated film 30 without a core layer 32, as shown in Figures 15A and 15B, is preferred over a transparent laminated film 30 including a core layer 32, as shown in Figures 15C and 15D. With a transparent laminated film 30 without a core layer 32, as shown in Figures 15A and 15B, it is particularly easy to reduce the thickness of the transparent laminated film 30 to 200 μm or less.

[0122] Furthermore, if the upper limit of the thickness of the transparent laminated film 30 is restricted as described above, the transparent laminated film 30 becomes more flexible. On the other hand, from the viewpoint of suppressing the formation of wrinkles (wavy shape) on the surface of the transparent laminated film 30 due to wind, etc., it is preferable that the transparent laminated film 30 is not easily bent beyond a certain point. By suppressing the formation of wrinkles (wavy shape) on the surface of the transparent laminated film 30 (first main surface 301, second main surface 302), the difficulty for the user to see the contents due to wrinkles (wavy shape) is suppressed.

[0123] The thickness of the transparent laminated film 30 may be, for example, 100 μm or more and 500 μm or less. A thickness of 100 μm or more makes the transparent laminated film 30 less flexible to the extent that wrinkles (wavy shape) on its surface are suppressed. Therefore, the self-supporting ability of the transparent laminated film 30 can be improved. Furthermore, a thickness of 500 μm or less allows for an effective increase in the sound pressure of the sound emitted from the transparent film 30, as described above.

[0124] Furthermore, the height (vertical distance) of the transparent laminated film 30 may be, for example, 60 mm or more and 1500 mm or less. Also, the width (horizontal distance) of the transparent laminated film 30 may be, for example, 200 mm or more and 3200 mm or less. As an example, the height and width of the transparent laminated film 30 may each be 400 mm. In this case, the sound pressure of the sound emitted from the transparent laminated film 30 can be effectively increased. Also, as an example, the height and width of the transparent laminated film 30 may be 1400 mm (height) x 3140 mm (width). In this case, by rolling the transparent laminated film 30 into a tube, a cylinder with a radius of curvature r and dimensions of 500 mm x 1400 mm (height) can be produced. Also, when the height of the transparent laminated film 30 is about 1400 mm, the radius of curvature r of the rolled-up transparent laminated film 30 may be about 500 mm or more. This can increase the self-supporting ability of the transparent laminated film 30. Furthermore, the radius of curvature r and height of the tubularly rolled transparent laminated film 30 may be 40 mm (radius of curvature r) × 140 mm (height), 150 mm (radius of curvature r) × 230 mm (height), or 250 mm (radius of curvature r) × 300 mm (height).

[0125] The transparent laminated film 30 described above has, for example, a bending stress of 6 N / 20 mm or less.

[0126] By using the transparent laminated film 30 described above in the sound device 10, light reflection in the sound device 10 is suppressed. For example, light reflection is suppressed compared to a sound device using a partition panel made of a typical acrylic sheet. Furthermore, by using the transparent laminated film 30 described above in the sound device 10, the transparency of the sound device 10 is improved. For example, the transparency of the sound device 10 is improved compared to a sound device using a partition panel made of a typical acrylic sheet.

[0127] It is preferable that the light reflectance of the transparent laminated film 30 described above is 3.0% or less. Here, the light reflectance of the transparent laminated film 30 refers to both the reflectance of light incident from the first main surface 301 side of the transparent laminated film 30 and the reflectance of light incident from the second main surface 302 side of the transparent laminated film 30. In other words, a light reflectance of 3.0% or less means that the reflectance of light incident from the first main surface 301 side of the transparent laminated film 30 is 3.0% or less, and the reflectance of light incident from the second main surface 302 side of the transparent laminated film 30 is 3.0% or less. This further improves the visibility of the transparent laminated film 30 when viewed from the first main surface 301 side and when viewed from the second main surface 302 side. It is more preferable that the light reflectance is 1.0% or less.

[0128] Furthermore, it is preferable that the total light transmittance (JIS K7361-1:1997) of the transparent laminated film 30 is 90% or more. This further improves the visibility of the transparent laminated film 30 when viewed from the first main surface 301 side, while also further improving the visibility of the transparent laminated film 30 when viewed from the second main surface 302 side. Moreover, it is more preferable that the total light transmittance of the transparent laminated film 30 is 92% or more, and even more preferable that it is 95% or more. Furthermore, it is preferable that the haze (JIS K7136:2000) of the transparent laminated film 30 is 3.0% or less, more preferably 2.0% or less, and even more preferably 1.5% or less.

[0129] In the transparent laminated film 30 described above, the arithmetic mean roughness Ra (JIS B0601:1994) of the first main surface 301 and the second main surface 302 is preferably 10 nm or less, and more preferably 1 nm to 8 nm. Furthermore, the ten-point mean roughness Rz (JIS B0601:1994) of the first main surface 301 and the second main surface 302 is preferably 160 nm or less, and more preferably 50 nm to 155 nm. If Ra and Rz are within the above ranges, the first main surface 301 and the second main surface 302 will have smoothness and improved scratch resistance.

[0130] In the transparent laminated film 30 described above, the puncture strength is preferably 10.0 N or higher. A sufficiently high puncture strength ensures sufficient strength to suppress damage to the transparent laminated film 30 when it is used in the sound device 10.

[0131] The puncture strength of the transparent laminated film 30 is measured in accordance with JIS Z1707 7.4. For example, a measuring device combining a Force Tester MCT-2150 manufactured by A&D Corporation and a puncture test jig JM-CL-100N also manufactured by A&D Corporation is used. Specifically, as shown in Figure 16, a needle 200 is inserted into a fixed specimen of the transparent laminated film 30 from the first main surface 301 side, and the maximum stress until the needle 200 penetrates the transparent laminated film 30 is measured. The needle 200 used has a diameter of 1.0 mm and a hemispherical tip with a radius of 0.5 mm. The speed at which the needle 200 is inserted into the transparent laminated film 30 is 50 mm / min (50 mm per minute). The maximum stress is measured for five specimens, and the average value is taken as the puncture strength of the transparent laminated film 30. The measurement environment is set to a temperature of 23°C and a relative humidity of 50%.

[0132] As described above, such an acoustic device 10 is a showcase that balances the protection and visibility of its contents (exhibits), and can be used as a showcase capable of emitting sound (see Figure 1). In other words, the acoustic device 10 can be used, for example, to separate the space in which the exhibits are displayed from the space in which people are present.

[0133] <Method for manufacturing transparent laminated film and acoustic device> Next, the manufacturing method of the transparent laminated film 30 and the sound device 10 according to this embodiment will be described. Here, first, the manufacturing method of the transparent laminated film 30 will be described.

[0134] First, the first anti-reflective layer 40 is fabricated. For example, first, a resin film constituting the first transparent substrate layer 42 is prepared. Next, a hard coat layer forming solution is applied to the resin film, dried, and irradiated with ultraviolet light to form the first hard coat layer 44. Then, a high refractive index layer forming solution is applied to the first hard coat layer 44, dried, and irradiated with ultraviolet light to form the first high refractive index layer 46. Next, a low refractive index layer forming solution is applied to the first high refractive index layer 46, dried, and irradiated with ultraviolet light to form the first low refractive index layer 45. In this way, the first anti-reflective layer 40 is obtained.

[0135] Next, a second anti-reflective layer 50 is prepared. For example, first, a resin film constituting the second transparent substrate layer 52 is prepared. Next, a hard coat layer forming solution is applied to the resin film, dried, and irradiated with ultraviolet light to form a second hard coat layer 54. Then, a high refractive index layer forming solution is applied to the second hard coat layer 54, dried, and irradiated with ultraviolet light to form a second high refractive index layer 56. Next, a low refractive index layer forming solution is applied to the second high refractive index layer 56, dried, and irradiated with ultraviolet light to form a second low refractive index layer 55. In this way, the second anti-reflective layer 50 is obtained.

[0136] Then, the first anti-reflective layer 40 and the second anti-reflective layer 50 are bonded to each other via the transparent adhesive layer 31 to produce a transparent laminated film 30. In this way, the transparent laminated film 30 can be produced.

[0137] Next, the first protective film 61 is attached to the first main surface 301 of the obtained transparent laminated film 30, and the second protective film 62 is attached to the second main surface 302. At this time, the first protective film 61 and the second protective film 62 may each include a bonding layer (not shown), and may be attached to the transparent laminated film 30 by this bonding layer. In this way, a transparent laminated film 60 with protective films can be manufactured. Note that the first protective film 61 and the second protective film 62 may be attached separately to the first anti-reflective layer 40 and the second anti-reflective layer 50, respectively, before the first anti-reflective layer 40 and the second anti-reflective layer 50 are bonded to each other via the transparent adhesive layer 31.

[0138] Next, the sound device 10 is fabricated.

[0139] First, the transparent laminated film 60 with a protective film is processed into a predetermined shape. When manufacturing the sound device 10 shown in Figure 1, the transparent laminated film 60 with a protective film is cut into a rectangular shape.

[0140] Next, the first protective film 61 and the second protective film 62 are removed from the transparent laminated film 60 with the protective film that has been processed into a predetermined shape. This results in a transparent laminated film 30 that has been processed into a predetermined shape.

[0141] Next, the transparent laminated film 30 is rolled into a tubular shape so that the first end face 303c and the second end face 303d face each other. At this time, the transducers 85 are attached to the first end face 303c and the second end face 303d of the transparent laminated film 30. The transducers 85 may be attached to the transparent laminated film 30 by means of adhesive or tape, for example. In this way, the acoustic device 10 is manufactured.

[0142] The sound device 10, thus constructed, is placed on a desk T, thereby dividing the room R into spaces R1 and R2. By activating the transducer 85, predetermined sounds such as music can be played through the transparent laminated film 30.

[0143] As described above, according to this embodiment, the sound device 10 comprises a transparent laminated film 30 having a first main surface 301, a second main surface 302 located on the opposite side of the first main surface 301, and an end surface 303 located between the first main surface 301 and the second main surface 302, and a vibrator 85 attached to the transparent laminated film 30. By activating the vibrator 85, sound is generated by the transparent laminated film 30 of the sound device 10, providing a comfortable environment for the user in space R1.

[0144] Furthermore, in this embodiment, the end face 303 has a first side end face 303c and a second side end face 303d that is different from the first side end face 303c. Also, the vibrator 85 has a first vibrating surface 87a and a second vibrating surface 87b located on the opposite side of the first vibrating surface 87a, with the first vibrating surface 87a in contact with the first side end face 303c and the second vibrating surface 87b in contact with the second side end face 303d. As a result, the vibration waves W1 and W2 (see Figure 6) from the vibrator 85 propagate along the circumferential direction as longitudinal waves LW. Therefore, the air in front of the first main surface 301 and the air in front of the second main surface 302 vibrates around the entire circumference. This makes it possible to increase the sound pressure of the sound emitted from the transparent film 30.

[0145] Furthermore, according to this embodiment, the transducer 85 vibrates along the normal direction N2 of the first end face 303c and the normal direction N3 of the second end face 303d. This allows the vibration waves W1 and W2 to be effectively transmitted to the transparent film 30. As a result, the sound pressure of the sound emitted from the transparent film 30 can be effectively increased.

[0146] Furthermore, according to this embodiment, the first side end face 303c includes a first contact surface 31c that contacts the first vibrating surface 87a of the vibrator 85, and a first protruding surface 32c that is adjacent to the first contact surface 31c and protrudes further toward the second vibrating surface 87b than the first contact surface 31c. The second side end face 303d includes a second contact surface 31d that contacts the second vibrating surface 87b of the vibrator 85, and a second protruding surface 32d that is adjacent to the second contact surface 31d and protrudes further toward the first vibrating surface 87a than the second contact surface 31d. As a result, when the vibrator 85 is sandwiched between the first contact surface 31c and the second contact surface 31d, the vibrator 85 can be supported by the first stepped surface 33c and the third stepped surface 33d. Therefore, the vibrator 85 can be easily fixed. Furthermore, for example, an overlapping region 36 is formed below the first contact surface 31c and below the second contact surface 31d where the transparent films 30 overlap. In this case, by providing a fixing member 91 so as to penetrate the overlapping region 36, the shape retention and self-supporting properties of the transparent film 30 can be improved.

[0147] Furthermore, according to this embodiment, the first side end face 303c is located on the opposite side of the first protruding surface 32c when viewed from the first contact surface 31c, and further includes a first recessed surface 34c that is recessed on the opposite side of the first contact surface 31c to the second contact surface 31d. Also, the second side end face 303d is located on the opposite side of the second protruding surface 32d when viewed from the second contact surface 31d, and further includes a second recessed surface 34d that is recessed on the opposite side of the second contact surface 31d to the first contact surface 31c. As a result, when the vibrator 85 is sandwiched between the first contact surface 31c and the second contact surface 31d, for example, an opening 37 is formed above the vibrator 85. Therefore, since the electric wire 85a can be passed through the opening 37 to a desired position, the box 95 can be placed in a desired position.

[0148] Furthermore, according to this embodiment, the transparent laminated film 30 is rolled into a tubular shape. This enhances the self-supporting ability of the transparent laminated film 30.

[0149] Furthermore, according to this embodiment, the transparent laminated film 30 includes a first anti-reflective layer 40 constituting the first main surface 301 and a second anti-reflective layer 50 constituting the second main surface 302. This suppresses the reflection of light incident from the first main surface 301 side of the transparent laminated film 30 and the reflection of light incident from the second main surface 302 side of the transparent laminated film 30. As a result, the visibility of the transparent laminated film 30 when viewed from the first main surface 301 side and the visibility when viewed from the second main surface 302 side can be improved. This makes it easier for users viewing the sound device 10 from the outside to see the contents. In addition, it is possible to suppress the discomfort and fatigue experienced by the user due to light reflected from the first main surface 301 or the second main surface 302 of the transparent laminated film 30.

[0150] In the embodiment described above, an example was given in which the transparent film 30 is rolled into a cylindrical shape, but this is not the only example. For example, as shown in Figure 17, the transparent film 30 may be formed in the shape of a frustocone. In this case, as shown in Figure 18, when the transparent film 30 is unfolded, the upper end surface 303a and the lower end surface 303b of the transparent film 30 extend to form arcs. Furthermore, the circle containing the arc formed by the upper end surface 303a and the circle containing the arc formed by the lower end surface 303b are concentric circles. Moreover, the length of the arc formed by the upper end surface 303a is shorter than the length of the arc formed by the lower end surface 303b. Even in this case, by operating the vibrator 85, sound can be generated by the transparent film 30, providing a pleasant environment for the user. In addition, the self-supporting ability of the transparent film 30 can be further improved by forming the transparent film 30 in the shape of a frustocone.

[0151] Furthermore, although not shown in the illustration, the transparent film 30 may be formed in the shape of an elliptical tube or a polygonal tube such as a square tube. Furthermore, although not shown in the illustration, the transparent film 30 may be formed in the shape of a cone, an elliptical cone, a polygonal pyramidal shape such as a square pyramid, or a frustum of an ellipse or a polygonal pyramidal pyramid such as a square pyramidal pyramid.

[0152] Furthermore, in the above-described embodiment, an example was given in which the first side end face 303c and the second side end face 303d face each other, but the embodiment is not limited to this. For example, as shown in Figures 19 and 20, the first side end face 303c and the second side end face 303d may be offset from each other in a plan view. Also, as shown in Figures 21 and 22, the transparent film 30 may be rolled up in a spiral shape. In these cases as well, the first vibrating surface 87a is in contact with the first side end face 303c and the second vibrating surface 87b is in contact with the second side end face 303d, so that the vibration waves W1 and W2 (see Figure 6) from the transducer 85 are transmitted along the circumferential direction as longitudinal waves LW. As a result, the air in front of the first main surface 301 and the air in front of the second main surface 302 vibrate all around. As a result, the sound pressure of the sound emitted from the transparent film 30 can be increased.

[0153] Furthermore, although the above-described embodiment describes an example in which the acoustic device 10 comprises one transparent film 30 and one vibrator 85, it is not limited to this. The acoustic device 10 may comprise multiple transparent films 30 and vibrators 85. For example, as shown in Figures 23 and 24, the acoustic device 10 may comprise multiple (two) transparent films 30 and one vibrator 85. In this case, as shown in Figures 23 and 24, the vibrator 85 may have a first vibrating surface 87a in contact with the first side end surface 303c of each transparent film 30, and a second vibrating surface 87b in contact with the second side end surface 303d of each transparent film 30. This allows for effective vibration of the air in front of each first main surface 301 and the air in front of each second main surface 302. As a result, the sound pressure of the sound emitted from the transparent film 30 can be effectively increased. Furthermore, as shown in Figure 25, the acoustic device 10 may also comprise multiple (3) transparent films 30 and multiple (2) transducers 85. In this case, two transducers 85 may be attached to a specific transparent film 30x. In these cases as well, the sound pressure of the sound emitted from the transparent film 30 can be increased. Although not shown in the figures, the acoustic device 10 may also comprise one transparent film 30 and multiple transducers 85. In addition, the acoustic device 10 may comprise three or more transparent films 30 and three or more transducers 85.

[0154] Furthermore, although the above-described embodiment describes an example in which the diaphragm is a transparent laminated film 30, it is not limited to this. For example, although not shown in the figures, the diaphragm may be a single-layer film, or a self-supporting member having a predetermined rigidity. [Examples]

[0155] Next, we will describe specific examples of the above embodiments.

[0156] (Examples) First, a transparent laminated film 30, as shown in Figure 15C, was fabricated. In this process, a first anti-reflective layer 40 was prepared. To prepare the first anti-reflective layer 40, a 60 μm thick triacetylcellulose film (refractive index 1.49) was prepared as the first transparent substrate layer 42. Next, a hard coat layer forming solution according to the following formulation was applied to the triacetylcellulose film, dried, and irradiated with ultraviolet light to form a first hard coat layer 44 with a thickness of 7.3 μm, a refractive index of 1.54, and a pencil hardness of 2H. Then, a high refractive index layer forming solution according to the following formulation was applied to this first hard coat layer 44, dried, and irradiated with ultraviolet light to form a first high refractive index layer 46 with a thickness of 150 nm and a refractive index of 1.63. Finally, a low refractive index layer forming solution according to the following formulation was applied to this first high refractive index layer 46, dried, and irradiated with ultraviolet light to form a first low refractive index layer 45 with a thickness of 100 nm and a refractive index of 1.30, thereby obtaining the first anti-reflective layer 40.

[0157] <Preparation of coating solution for hard coat layer formation> 1.6 parts by mass of a photopolymerization initiator (BASF, Irgacure 127, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one) and 58.3 parts by mass of a diluent (methyl isobutyl ketone / cyclohexanone = 8 / 2) were added and stirred until no undissolved particles remained. 20 parts by mass of a photocurable resin (Arakawa Chemical, Beamset 577) and 20 parts by mass of a high refractive index resin (DIC Corporation, Polylight RX-4800) were added and stirred until no undissolved particles remained. Finally, 0.1 parts by mass of a leveling agent (Dainichi Seika Kogyo, Seika Beam 10-28 (MB)) were added and stirred to prepare a coating solution for hard coat layer formation.

[0158] <Preparation of coating solution for forming a high refractive index layer> 0.1 parts by mass of photopolymerization initiator (BASF, Irgacure 127) and 92.6 parts by mass of diluent (methyl isobutyl ketone / cyclohexanone / methyl ethyl ketone = 4 / 2 / 4) were added and stirred until no undissolved particles remained. 1.25 parts by mass of photocurable resin (Arakawa Chemical, Beamset 577) was added and stirred until no undissolved particles remained. 6 parts by mass of zirconium oxide (Sumitomo Osaka Cement, MZ-230X, solid content 32.5% by mass, average primary particle size 15-50 nm) and 0.05 parts by mass of leveling agent (Dainichi Seika Kogyo, Seika Beam 10-28 (MB)) were added and stirred to prepare a coating solution for forming a high refractive index layer.

[0159] <Preparation of coating solution for forming a low refractive index layer> 0.2 parts by mass of photopolymerization initiator (BASF, Irgacure 127) and 91.1 parts by mass of diluent (MIBK / AN=7 / 3) were added and stirred until no undissolved particles remained. 1.0 part by mass of photocurable resin (Nippon Kayaku Co., Ltd., KAYARAD-PET-30), 7.6 parts by mass of hollow silica particles (solid content 20% by mass, average primary particle size 60 nm), and 0.1 parts by mass of leveling agent (Dainichi Seika Kogyo Co., Ltd., Seika Beam 10-28 (MB)) were added and stirred to prepare a coating solution for forming a low refractive index layer.

[0160] Next, a second anti-reflective layer 50 was fabricated. To fabricate the second anti-reflective layer 50, first, a triacetylcellulose film with a thickness of 60 μm (refractive index 1.49) was prepared as a second transparent substrate layer 52. Next, the hard coat layer forming solution according to the above formulation was applied to the triacetylcellulose film, dried, and irradiated with ultraviolet light to form a second hard coat layer 54 with a thickness of 7.3 μm, a refractive index of 1.54, and a pencil hardness of 2H. Then, the high refractive index layer forming solution according to the above formulation was applied to this second hard coat layer 54, dried, and irradiated with ultraviolet light to form a second high refractive index layer 56 with a thickness of 150 nm and a refractive index of 1.63. Then, the low refractive index layer forming solution according to the above formulation was applied to this second high refractive index layer 56, dried, and irradiated with ultraviolet light to form a second low refractive index layer 55 with a thickness of 100 nm and a refractive index of 1.30, thereby obtaining the second anti-reflective layer 50.

[0161] Next, the first anti-reflective layer 40 and the second anti-reflective layer 50 were bonded to each other via a transparent adhesive layer (Panac Corporation, Panaclean series PD-S1, 25 μm thick), a 60 μm thick triacetylcellulose film, and another transparent adhesive layer (Panac Corporation, Panaclean series PD-S1, 25 μm thick) to produce a transparent laminated film 30. The layer structure of the obtained transparent laminated film 30 is as follows.

[0162] Low flexion / High flexion / Hard court / TAC / Sticky / TAC / Sticky / TAC / Hard court / High flexion / Low flexion In the above, "low refractive index" refers to the first low refractive index layer or the second low refractive index layer (the same applies hereinafter). Also, "high refractive index" refers to the first high refractive index layer or the second high refractive index layer (the same applies hereinafter). Also, "hard coat" refers to the first hard coat layer or the second hard coat layer (the same applies hereinafter). Also, "TAC" refers to triacetylcellulose film (the same applies hereinafter). Furthermore, "adhesive" refers to the transparent adhesive layer. The thickness of the transparent laminated film 30 in the example was 250 μm. The height and width of the transparent laminated film 30 were 220 mm and 900 mm, respectively.

[0163] Next, the transducer 85 was attached to the transparent laminated film 30. The transducer 85 was attached to the first end face 303c and the second end face 303d such that the first vibrating surface 87a of the transducer 85 contacted the first end face 303c, and the second vibrating surface 87b of the transducer 85 contacted the second end face 303d. The transducer 85 was also attached approximately in the center in the vertical direction. The transducer 85 used was a piezoelectric speaker (manufactured by TDK Corporation, PiezoListen®). At this time, the radius of curvature r of the transparent laminated film 30 was 140 mm.

[0164] (1) Sound pressure measurement Next, sound pressure was measured. The measuring device used was a sound level meter (NL-42 (product name)) manufactured by Rion Co., Ltd. In this case, as shown in Figure 26, the sound pressure level was measured from directions (1) to (5). At this time, the measuring device was placed near the transparent laminated film 30 in each case. When measuring from directions (1) to (4), the measuring device was placed on the first main surface 301 side and the second main surface 302 side of the transparent laminated film 30, respectively. The measurements were taken in a room with an ambient noise of 33 dB and a room temperature of 25 °C. White noise was used as the sound source. The volume of the sound source was defined as the volume at which the first vibration surface 87a was attached to the first main surface 301 of the transparent laminated film 30 (as shown in Figure 5), resulting in a volume of 70 dB.

[0165] Furthermore, the sound pressure was measured with the measuring device separated from the transparent laminated film 30. In this case, when measuring from directions (1) to (4), the measuring device was placed approximately 1 m away from the second main surface 302 of the transparent laminated film 30. When measuring from direction (5), the measurement was performed with the sound device 10 lying horizontally. In this case, the measuring device was placed approximately 1 m away from the upper end surface 303a of the transparent laminated film 30. The measurements were performed in a room with an ambient noise level of 33 dB. White noise was used as the sound source. The volume of the sound source was set to the volume at which the first vibrating surface 87a was attached to the first main surface 301 of the transparent laminated film 30 reached 70 dB.

[0166] The results are shown in Tables 1 and 2. Table 1 shows the measurement results when the measuring device was placed near the transparent laminated film 30. Table 2 shows the measurement results when the measuring device was placed approximately 1 m away from the transparent laminated film 30.

[0167] [Table 1]

[0168] [Table 2]

[0169] As a result, as shown in Tables 1 and 2, it was found that the acoustic device according to the example could obtain high sound pressure. Furthermore, as shown in Table 1, it was found that the sound pressure on the first main surface 301 side of the transparent laminated film 30 (the inside side of the acoustic device 10) was about 6 dB to 14 dB higher than on the second main surface 302 side of the transparent laminated film 30 (the outside side of the acoustic device 10).

[0170] Furthermore, as shown in (2) and (4) of the measurement method column in Tables 1 and 2, it was found that the sound pressure effectively increased when the transducer 85 was rotated 90° in the circumferential direction.

[0171] The multiple components disclosed in each of the above embodiments and variations can be combined as needed. Alternatively, some components may be removed from all the components shown in each of the above embodiments and variations.

[0172] In addition to being used as a showcase as shown in Figure 1, the sound device 10 of this disclosure may also be suspended from a support 99, for example, as shown in Figures 27 to 30. In this case, as shown in Figures 27 and 28, the sound device 10 may be positioned in a predetermined location so that the user hears the sound from around the sound device 10. Alternatively, as shown in Figure 29, the sound device 10 may be positioned above the user's head. In these cases, the sound device 10 may be used as a lighting device by installing a light source inside the transparent laminated film 30. Furthermore, as shown in Figure 30, the sound device 10 may be positioned to surround the user's head.

[0173] Furthermore, as shown in Figures 31 and 32, the sound device 10 may also be used as a partition surrounding each user in a smoking area or the like. In this case, as shown in Figure 31, the sound device 10 may surround only the vicinity of the user's head, or as shown in Figure 32, it may surround the user's entire body. By arranging the sound device 10 to surround the viewer, a highly immersive sound space can be provided as an immersive display.

[0174] Furthermore, the acoustic device disclosed herein can be used in applications that require both visibility and sound insulation, masking, or active noise cancellation. For example, the acoustic device disclosed herein can be used as a remote meeting booth in an office. It can also be used as a transparent film that emits sounds such as music, in combination with floating screens (Japanese Patent Application Nos. 2023-063100, 2023-063101) or transparent screens (https: / / www.dnp.co.jp / news / detail / 1190062_1587.html) for more eye-catching advertisements, or as a frame for paintings or photographs. It is desirable to use glass or the like instead of film as the core layer 32 shown in Figures 15C, 15D, and 15F to enhance self-supporting properties. [Explanation of symbols]

[0175] 10 Sound equipment 30 Transparent Laminated Film 31c 1st contact surface 31d 2nd contact surface 32c 1st protruding surface 32d 2nd protruding surface 34c First depression 34d Second depression 40 First anti-reflection layer 50 Second anti-reflection layer 85 transducer 87a 1st vibration plane 87b 2nd vibration plane 301 First Main Surface 302 Second Main Surface 303 End face 303c 1st side end surface 303d 2nd side end face

Claims

1. It is an acoustic device, A diaphragm having a first main surface, a second main surface located opposite the first main surface, and an end surface located between the first main surface and the second main surface, The system comprises a vibrator attached to the diaphragm, The end face has a first end face and a second end face that is different from the first end face. The vibrator has a first vibrating surface and a second vibrating surface located on the opposite side of the first vibrating surface. The first vibrating surface is in contact with the first end face, The second vibrating surface is in contact with the second end face of the acoustic device.

2. The acoustic device according to claim 1, wherein the vibrator vibrates along the direction normal to the first end face and the direction normal to the second end face.

3. The acoustic device according to claim 1, wherein the diaphragm is rolled into a tubular shape.

4. The acoustic device according to claim 3, wherein the radius of curvature of the diaphragm is 10 mm or more and 500 mm or less.

5. The acoustic device according to claim 1, wherein the thickness of the diaphragm is 100 μm or more and 500 μm or less.

6. The first end face includes a first contact surface that contacts the first vibrating surface, and a first protruding surface that is adjacent to the first contact surface and protrudes further toward the second vibrating surface than the first contact surface. The acoustic device according to claim 1, wherein the second end face includes a second contact surface that contacts the second vibrating surface and a second protruding surface that is adjacent to the second contact surface and protrudes toward the first vibrating surface than the second contact surface.

7. The first end face is located on the opposite side of the first protruding surface when viewed from the first contact surface, and further includes a first recessed surface that is recessed on the opposite side of the first contact surface from the second contact surface, The acoustic device according to claim 6, wherein the second end face is located on the opposite side from the second protruding surface when viewed from the second contact surface, and further includes a second recessed surface that is recessed on the opposite side from the first contact surface compared to the second contact surface.

8. The acoustic device according to any one of claims 1 to 7, wherein the diaphragm includes a first anti-reflective layer constituting the first main surface and a second anti-reflective layer constituting the second main surface.

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