TW202301019A - Projection screen - Google Patents

Abstract

The present invention addresses the problem of preventing, in a projection screen in which a piezoelectric acoustic film is adhered to the rear surface-side, audio output at the rear surface-side from wrapping around to the projection surface-side. The problem is solved by having a screen body, a piezoelectric acoustic film adhered to the surface on the reverse side of the video projection surface of the screen body, and a sound-insulating sheet that is provided so as to cover the surface on the reverse side of the projection surface of the screen body.

Description

projection screen

The invention relates to a projection screen for projecting images.

Image projection systems that project images onto a screen for interference are used in conferences, home theaters, etc. In such an image projection system, sound as important as an image is provided, for example, by speakers arranged behind and/or beside the screen on which the image is projected. However, in these systems, a space for arranging speakers is required.

In contrast, there is also known a method in which a piezoelectric acoustic film is attached to the back of a screen on which an image is projected, and the piezoelectric acoustic film vibrates the screen to output sound from the screen.

For example, in Patent Document 1, it is described that it has a screen surface for displaying image information, a piezoelectric layer formed on the back of the screen surface, electrodes for supplying power to the piezoelectric layer, and modulating an audio signal according to the supplied power. The screen of the modulation circuit. In Patent Document 2, a projection screen is described in which a speaker composed of a piezoelectric acoustic film (piezoelectric film) with electrode films layered on both sides is attached to either the back or the front of a sheet-shaped screen body.

[Patent Document 1] Japanese Unexamined Patent Publication No. 2006-339954 [Patent Document 2] Japanese Unexamined Patent Publication No. 2007-187976

The screen in which the piezoelectric acoustic film is provided on the back of the projection surface vibrates the entire surface of the screen by driving the piezoelectric acoustic film, and outputs sound by the vibration of the screen. Therefore, in a screen having such a piezoelectric acoustic film, it is possible to obtain a high sense of presence as if sound is output from an image.

However, when actually viewing a video, it is preferable that the sound is output only from the projection surface side of the video. However, according to studies by the inventors of the present invention, in a configuration in which a piezoelectric acoustic film is attached to the back of the screen, since the entire surface of the screen vibrates, sound is also output from the back side. The sound output from the rear side surrounds the projection surface side and is also output from the projection surface side.

The sound output from the rear side is the sound with the opposite phase to that of the projection surface side. Therefore, if the sound output from the rear side surrounds the projection surface side, it will cancel a part of the sound output from the projection surface side, and when the image is viewed on the projection surface side, the sound output will be reduced.

The purpose of the present invention is to solve the problems of the prior art, and to provide a projection screen with a piezoelectric acoustic film attached to the back side of the screen, which can prevent the sound output from the back side from surrounding the projection surface side, and prevent Projection screen with reduced sound output on the projection surface side.

In order to achieve this object, the present invention has the following constitutions. [1] A projection screen, characterized by having: The screen body is used to project images; Piezoelectric acoustic film attached to the surface of the screen body opposite to the projection surface of the image; and The soundproof sheet is arranged to cover the surface of the screen body opposite to the projection surface. [2] The projection screen as described in [1], wherein There is a space between the screen body, the piezoelectric sound film and the sound insulation sheet. [3] The projection screen as described in [1] or [2], wherein The sound insulation sheet can be loaded and unloaded. [4] The projection screen according to any one of [1] to [3], wherein Piezoelectric acoustic films are flexible. [5] The projection screen according to any one of [1] to [4], which has: a first supporting member supporting one side of the screen body and a second supporting member supporting the side of the screen body opposite to the side supported by the first supporting member; and A stretching mechanism that brings the first supporting member closer to and apart from the second supporting member. [6] The projection screen as described in [5], which has: The fine adjustment mechanism adjusts the distance between the first support member and the second support member in a state where the first support member and the second support member are separated by the stretching mechanism. [7] The projection screen according to any one of [1] to [6], wherein The piezoelectric acoustic film has a piezoelectric body layer and electrode layers provided on both surfaces of the piezoelectric body layer. [8] The projection screen as described in [7], wherein The piezoelectric layer is a polymer composite piezoelectric body having piezoelectric particles in a polymer material. [9] The projection screen as described in [8], wherein The polymer material of the polymer composite piezoelectric body is cyanoethylated polyvinyl alcohol. [Invention effect]

According to the present invention, in the projection screen on which the piezoelectric acoustic film is attached on the front side, it is possible to prevent the sound output from the back side from going around to the projection surface side, and to prevent the sound output from being lowered when the image is viewed on the projection surface side.

Hereinafter, the projection screen of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

The description of the constituent requirements described below may be based on representative embodiments of the present invention, but the present invention is not limited to these embodiments. In addition, the figures shown below are schematic diagrams for explaining the projection screen of the present invention, and the size, thickness, shape, and positional relationship of each member are different from the actual object. In addition, in this specification, the numerical range represented using "-" means the range which includes the numerical value described before and after "-" as a lower limit and an upper limit.

An example of the projection screen of the present invention is schematically shown in FIG. 1 . In addition, in FIG. 1 , the figure on the left side is a figure viewing the projection screen of the present invention from the rear side, and the figure on the right side is a cross section along line A-A of the figure on the left side. In addition, the back side means the surface side of the screen main body on which the image is projected, which is opposite to the projection surface of the image.

The projection screen 10 shown in FIG. 1 has a screen main body 50 for projecting images, a piezoelectric acoustic film 24 attached to the back side of the screen main body 50, a first support member 52 and a second support member 54 for supporting the screen main body 50. , stretching mechanism 56, sound insulation sheet 59 and foot member 78. In addition, in FIG. 1 , in the rear view on the left side, the soundproof sheet 59 is omitted in order to clearly show the configuration of the projection screen 10 , but the soundproof sheet 59 is provided on the projection screen 10 as shown in the cross-sectional view on the right side. to cover the entire surface of the rear side of the screen body 50 (see FIG. 12 ). In the sectional view on the right, hatching is omitted in order to clearly show the configuration of the projection screen 10 .

In the present invention, the first and second of the first supporting member 52 and the second supporting member 54 are additions to the projection screen 10 of the present invention for the purpose of distinguishing each member and for convenience of description. Therefore, the terms 1 and 2 in support members and the like have no technical meaning, and are irrelevant to positions, usage conditions, and the like.

In the illustrated example, the screen body 50 is a known projection screen for projecting images. In the illustrated example, the screen body 50 is rectangular, one long side is supported by the first supporting member 52 , and the other long side is supported by the second supporting member 54 . The first supporting member 52 and the second supporting member 54 are detachably supported by a stretching mechanism 56 for moving the first supporting member 52 and the second supporting member 54 closer to and apart from each other. The stretching mechanism 56 has a cylindrical first frame member 58 and a second frame member 60 . A freely bendable hinge member 62 is engaged with both ends of the first frame member 58 and the second frame member 60 . As will be described later, the first support member 52 and the second support member 54 are detachably pulled by engaging the first support member 52 with the first frame member 58 and the second support member 54 with the second frame member 60 . Stretching mechanism 56 supports. By bending the hinge member 62, the first frame member 58, that is, the first support member 52, is close to the second frame member 60, that is, the second support member 54 (see FIG. 5 ), as shown in FIG. 1 , by extending the hinge The member 62 separates the first support member 52 which is the first frame member 58 from the second support member 54 which is the second frame member 60 . The state in which the hinge member 62 is extended linearly to separate the first support member 52 from the second support member 54 is the state of the stretched screen body 50 . The hinge member 62 is detachably supported by the foot member 78 by engaging the both ends of the first frame member 58 and the second frame member 60 with the foot member 78 . The leg members 78 are used to support the screen main body 50 in a state of standing upright when projecting images. The above configuration will be described in detail later.

As mentioned above, the screen body 50 is a known projection screen for projecting images. Therefore, as long as the screen main body 50 is capable of projecting images, it is possible to use various materials such as resins such as vinyl chloride, paper such as Japanese paper, and cloth such as canvas (campus) that can project images.

Also, like a general projection screen, the screen main body 50 is flexible, and is rolled up to the first supporting member 52 and/or the second supporting member 54 when not in use.

The screen body 50 may have light transmission or light shielding properties. However, from the viewpoint of better displaying the projected image and preventing the piezoelectric acoustic film 24 attached to the back from being visually recognized by the viewer of the image, it is preferable that the screen body 50 has light-shielding properties.

As described above, in the projection screen 10 , one long side of the screen main body 50 is supported by the first supporting member 52 , and the other long side is supported by the second supporting member 54 . As schematically shown in FIG. 2 , the first supporting member 52 is composed of a cylindrical main body 52 a and a C cover 52 b covering the main body 52 a except for a part. One long side of the screen body 50 is supported by the first supporting member 52 by being sandwiched between the body 52a and the C cover 52b. Similarly, the second supporting member 54 is composed of a cylindrical main body 54a and a C cover 54b covering the main body except for a part (see FIG. 4 ). Similarly, the long side opposite to the first support member 52 side of the screen main body 50 is supported by the second support member 54 by being sandwiched between the main body 54 a and the C cover 54 b.

The first supporting member 52 and the second supporting member 54 are detachably supported by a stretching mechanism 56 for moving the first supporting member 52 and the second supporting member 54 closer to and apart from each other. The stretching mechanism 56 has a cylindrical first frame member 58 and a second frame member 60 and two hinge members 62 .

The hinge member 62 has a plate-shaped first arm 62a and a second arm 62b. The 1st arm 62a and the 2nd arm 62b are rotatably connected by connecting one end part by the rotating shaft 62c. The stretching mechanism 56 engages one hinge member 62 near one end of the first frame member 58 and the second frame member 60 , and engages one hinge member 62 near the other end of the first frame member 58 and the second frame member 60 . The other hinge member 62 is engaged to form a square frame shape.

The first frame member 58 is engaged with the first arm 62a of the hinge member 62 near both ends. Specifically, as schematically shown in FIG. 3 , the first frame member 58 has engaging members 58 a near both ends. The engaging member 58a is engaged with the end of the first arm 62a of the hinge member 62 via the rotating shaft 62d, so that the first frame member 58 and the first arm 62a, that is, the hinge member 62 are rotatably engaged. On the other hand, the second frame member 60 is engaged with the second arm 62b of the hinge member 62 near both ends. Specifically, as schematically shown in FIG. 4 , the second frame member 60 has engagement members 60 a near both ends. The engaging member 60a is engaged with the end portion of the second arm 62b of the hinge member 62 via the rotating shaft 60f, so that the second frame member 60 and the second arm 62b, that is, the hinge member 62 are rotatably engaged. 3 and 4, although the first support member 52, the second support member 54, the first frame member 58, and the second frame member 60 are cross-sectional, hatching is omitted for simplification of the drawings.

Therefore, the first frame member 58 and the second frame member 60 are approached by bending the hinge member 62, and the first frame member 58 and the second frame member can be aligned by extending the hinge member 62 from the bent state to a straight line. 60 apart. As described above, the first support member 52 is supported by the first frame member 58 , and the second support member 54 is supported by the second frame member 60 . Therefore, the first support member 52 and the second support member 54 can be moved closer to and separated from each other by bending and extending the hinge member 62 . Also, the hinge member 62 is linearly extended or slightly bent by a known method such as a fixing member capable of fixing and releasing the fitting between the concave portion and the convex portion and moving in the longitudinal direction.

As shown in FIG. 3 , in the first frame member 58 , fixing pins 58 b are provided at specific intervals along the longitudinal direction. Moreover, the main body 52a of the 1st support member 52 is provided with the through-hole 52c corresponding to the fixing pin 58b. By inserting the fixing pin 58b of the first frame member 58 into the through hole 52c of the first support member 52, the first support member 52 is detachably supported by the tension mechanism 56 which is the first frame member 58. As shown in FIG. 4, the second frame member 60 is also provided with fixing pins 60b at predetermined intervals along the longitudinal direction. Moreover, the main body 54a of the 2nd support member 54 is provided with the through-hole 54c corresponding to the fixing pin 60b. By inserting the fixing pin 60b of the second frame member 60 into the through hole 54c of the second support member 54, the second support member 54 is detachably supported by the tension mechanism 56 which is the second frame member 60.

In addition, as shown in FIG. 1 , in the first frame member 58 of the stretching mechanism 56, there is a device for adjusting the distance between the first support member 52 and the second support member 52 and the second support member 58 by adjusting the distance between the first support member 52 and the first frame member 58. The interval between the components 54 is used to adjust the micro-adjustment mechanism 80 of the tension of the screen body 50 . The fine adjustment mechanism 80 will be described in detail later.

The stretching mechanism 56 supporting the first support member 52 and the second support member 54 is detachably supported by two leg members 78 at both ends of the first frame member 58 and the second frame member 60 . The leg member 78 is a rod-shaped member installed upright at the installation position of the projection screen 10 , and is used to support the screen main body 50 in a state where the screen main body 50 is installed upright when projecting an image. In the lower end portion of the leg member 78 , a leg portion 78 c is provided to maintain an upright installation state when the stretching mechanism 56 , that is, the screen main body 50 is supported.

In the leg member 78, an upper support member 78a and a lower support member 78b are fixed. Both the upper support member 78a and the lower support member 78b are rod-shaped members. The upper support member 78 a is inserted into the first frame member 58 of the stretching mechanism 56 . On the other hand, the lower supporting member 78 b is inserted into the second frame member 60 of the stretching mechanism 56 . Thereby, the foot member 78 supports the stretching mechanism 56 . In addition, in the foot member 78, an upper support member 78a is fixed. On the other hand, the lower support member 78b is detachably fixed while changing its height, that is, its position in the longitudinal direction of the leg member 78 .

Hereinafter, referring to the schematic diagrams of FIGS. 5 to 7 , the stretching method of the screen body 50 in the projection screen 10 will be described. In addition, also in FIGS. 5 to 7 , the soundproof sheet 59 is omitted in order to clearly show the configuration of the projection screen 10 .

First, as shown in FIG. 5, the upper supporting members 78a of the leg members 78 are inserted into both ends of the first frame member 58 of the stretching mechanism 56, and the stretching mechanism 56 is supported by the leg members 78 standing upright.

As described above, the screen main body 50 supports one side in the longitudinal direction by the first support member 52 , supports the other side by the second support member 54 , and is wound around the first support member 52 and/or the second support member 54 . Unfold the screen body 50 wound on the first support member 52 and/or the second support member 54, and insert the fixing pin 58b of the first frame member 58 into the through-hole 52c of the first support member 52 (main body 52a) (see Fig. 3). Furthermore, the fixing pin 60b of the 2nd frame member 60 is inserted into the through-hole 54c of the 2nd support member 54 (main body 54a) (refer FIG. 4). Thereby, the first supporting member 52 and the second supporting member 54 , that is, the screen main body 50 are supported by the stretching mechanism 56 .

At this point in time, as shown in FIG. 5 , the hinge member 62 of the stretching mechanism 56 is bent. Next, as shown in FIG. 6 , the hinge member 62 is extended linearly. Thereby, the first frame member 58 and the second frame member 60 , that is, the first support member 52 and the second support member 54 are separated, and the screen main body 50 is stretched.

Furthermore, as shown in FIG. 7 , the lower support member 78 b is inserted into the second frame member 60 to fix the lower support member 78 b to the leg member 78 , and the screen body 50 is fixed in a stretched state.

Wherein, in the first frame member 58 of the stretching mechanism 56, there is a space between the first support member 52 and the second support member 54 by adjusting the distance between the first support member 52 and the first frame member 58, so as to A micro-adjustment mechanism 80 for adjusting the tension of the screen body 50 . In the illustrated example, as an example, four fine adjustment mechanisms 80 are provided at equal intervals along the longitudinal direction. When the lower support member 78b is inserted into the second frame member 60 and fixed, if the tension of the screen body 50 is insufficient, the first frame member 58 and the first support member 52 are widened by the fine adjustment mechanism 80 The distance between them is to stretch the screen body 50 more. On the contrary, when the lower support member 78b is inserted into the second frame member 60 to fix it, when the tension of the screen body 50 is too strong, the first frame member 58 and the first support member are aligned by the fine adjustment mechanism 80. 52 is narrowed to reduce the tension of the screen body 50 .

The fine adjustment mechanism 80 is not limited, and a known method of adjusting the distance between two bar-shaped members arranged in parallel in a direction perpendicular to the longitudinal direction can be used. As an example, as schematically shown in FIG. 2 , the method of using the adjustable screw 80a that is idling in the first frame member 58 and screwed in the first support member 52 (body 52a) and the use of a cam mechanism are shown. method etc.

In the illustrated example, four fine adjustment mechanisms 80 are provided as an example. However, the present invention is not limited thereto, as long as the distance between the first support member 52 and the first frame member 58 can be adjusted uniformly along the longitudinal direction, the number of micro-adjustment mechanisms 80 can be 3 or less, or 5. above.

Again, carry out the steps opposite to the steps described in FIGS. Take the first support member 52 and/or the second support member 54. Furthermore, in the first supporting member 52, the C cover 52b is detached from the main body 52a, and in the second supporting member 54, the C cover 54b is detached from the main body 54a, so that the screen main body 50 can be removed from the first supporting member. 52 and the second support member 54.

In addition, in the projection screen of the present invention, the stretching mechanism of the screen body 50 is not limited to the illustrated example, and various known stretching mechanisms of screens for projecting images can be used. That is, as long as the projection screen of the present invention has the screen body 50, the piezoelectric acoustic film 24 attached to the back side of the screen body 50, and the soundproof sheet 59 covering the back side of the screen body, known projection screens can be used. Various stretching mechanisms in the screen.

In the projection screen 10 having such a stretching mechanism of the screen body 50, the piezoelectric acoustic film 24 is attached to the back surface of the screen body 50, that is, the surface opposite to the image projection surface.

In the illustrated example, two piezoelectric acoustic films 24 are attached separately along the longitudinal direction of the screen main body 50 for stereo reproduction of sound. However, in the present invention, the number of piezoelectric acoustic films 24 is not limited, and the piezoelectric acoustic films 24 may be one, four or more. Also, the attachment position of the piezoelectric acoustic film on the screen body 50 can be appropriately set according to the size of the screen body 50, the size of the piezoelectric acoustic film 24 in the direction of the screen body 50, the number of piezoelectric acoustic films 24, etc. .

In the projection screen 10, the piezoelectric acoustic film 24 vibrates the screen main body 50 to output sound. In the present invention, the piezoelectric acoustic film 24 is not limited, and various known piezoelectric acoustic films 24 that vibrate the screen body 50 to output sound by being attached to the back side of the screen on which images are projected can be used.

FIG. 8 schematically shows an example of the piezoelectric acoustic film 24 with a cross-sectional view. In FIG. 8 and the like, hatching will be omitted in order to simplify the drawing to clearly show the structure. In addition, in the following description, unless otherwise specified, "cross-section" means a cross-section in the thickness direction of the piezoelectric acoustic film. The thickness direction of the piezoelectric acoustic film refers to the lamination direction of each layer.

The piezoelectric acoustic film 24 shown in FIG. 8 has a piezoelectric body layer 26, a first electrode layer 28 on one surface layer of the piezoelectric body layer 26, a first protective layer 32 laminated on the first electrode layer 28, and a first protective layer 32 on the piezoelectric body layer 26. The second electrode layer 30 and the second protective layer 34 laminated on the second electrode layer 30 are another surface layer of the bulk layer 26 .

In the piezoelectric acoustic film 24 , the piezoelectric layer 26 is not limited, and various known piezoelectric layers used for various piezoelectric acoustic films (piezoelectric films) can be used. In the piezoelectric acoustic film 24, the piezoelectric layer 26 is preferably a polymer composite piezoelectric body in which piezoelectric particles 40 are contained in a polymer matrix 38 comprising a polymer material as schematically shown in FIG. 8 . .

Among them, it is preferable that the polymer composite piezoelectric body (piezoelectric body layer 26 ) has the following requirements. In addition, in this invention, normal temperature means 0-50 degreeC. (i) Flexibility For example, when a portable document such as a newspaper or a magazine is held in a state where it feels like it is being bent slowly, relatively slow and large bending deformation of several Hz or less is continuously received from the outside. At this time, if the polymer composite piezoelectric body is hard, relatively large bending stress may be generated to cause cracks at the interface between the polymer matrix and the piezoelectric body particles, which may eventually lead to destruction. Therefore, appropriate flexibility is required for the polymer composite piezoelectric body. Moreover, if strain energy can be diffused to the outside as heat, stress can be relaxed. Therefore, the loss tangent of the polymer composite piezoelectric body is required to be appropriately large. (ii) Acoustic quality The speaker vibrates piezoelectric particles at a frequency in the audio frequency range of 20 Hz to 20 kHz, and the vibrating energy vibrates the vibration plate (polymer composite piezoelectric body) as a whole to reproduce sound. Therefore, in order to improve the transmission efficiency of vibration energy, appropriate hardness is required for the polymer composite piezoelectric body. Also, if the frequency characteristics of the speaker are smooth, the amount of change in sound quality when the lowest resonance frequency f ₀ changes with changes in the curvature is also small. Therefore, the loss tangent of the polymer composite piezoelectric body is required to be appropriately large.

此時，由於壓電音響薄膜的彎曲程度亦即彎曲部的曲率半徑變得越大，則機械剛性s下降，因此最低共振頻率f ₀變小。亦即，有時依據壓電音響薄膜的曲率半徑而改變揚聲器的音質（音量、頻率特性）。 As is well known, the lowest resonance frequency f ₀ of a speaker diaphragm is given by the following equation. Among them, s is the rigidity of the vibration system, and m is the mass. [mathematical formula 1]

At this time, as the degree of curvature of the piezoelectric acoustic film, that is, the radius of curvature of the curved portion increases, the mechanical rigidity s decreases, and therefore the minimum resonance frequency f ₀ decreases. That is, the sound quality (volume, frequency characteristics) of the speaker may change depending on the curvature radius of the piezoelectric acoustic film.

To sum up, it is required that the polymer composite piezoelectric body exhibits rigidity for vibrations of 20 Hz to 20 kHz and softness for vibrations of several Hz or less. In addition, the loss tangent of the polymer composite piezoelectric body is required to be appropriately large with respect to vibrations at all frequencies below 20 kHz.

Generally, polymer solids have a viscoelastic relaxation mechanism, and as the temperature increases or the frequency decreases, large-scale molecular motion acts as a decrease (relaxation) in the storage elastic coefficient (Young's modulus) or a maximization of the loss elastic coefficient ( absorption) was observed. Among them, the relaxation caused by the Micro Brownian motion of the molecular chains in the amorphous region is called the main dispersion, and a very large relaxation phenomenon can be observed. The temperature at which this primary dispersion occurs is the glass transition point (Tg), where the viscoelastic relaxation mechanism is most evident. In the polymer composite piezoelectric body (piezoelectric body layer 26), by using a polymer material with a glass transition point at room temperature, in other words, a polymer material with viscoelasticity at room temperature, for the matrix, it is possible to achieve a frequency range of 20 Hz to 20 Hz. A polymer composite piezoelectric body that operates hard at vibrations of 20kHz and soft at slow vibrations below a few Hz. In particular, it is preferable to use a polymer material having a glass transition point Tg at room temperature at a frequency of 1 Hz for the matrix of the polymer composite piezoelectric body, from the viewpoint of expressing the motion preferably.

It is preferable that the maximum value of the loss tangent Tanδ at a frequency of 1 Hz based on a dynamic viscoelasticity test of the polymer material used as the polymer matrix 38 is 0.5 or more at room temperature. Thereby, when the polymer composite piezoelectric body is slowly bent by an external force, the stress concentration at the interface of the polymer matrix/piezoelectric body particle in the maximum bending moment portion is alleviated, and high flexibility can be expected.

In addition, the polymer material used as the polymer matrix 38 is preferably as follows, that is, the storage elastic coefficient (E') at a frequency of 1 Hz based on dynamic viscoelasticity measurement is 100 MPa or more at 0°C, and at 50°C It is below 10MPa. Thereby, the bending moment generated when the polymer composite piezoelectric body is slowly bent by an external force can be reduced, and at the same time, it can be relatively hard for the acoustic vibration of 20 Hz to 20 kHz.

Moreover, it is more preferable that the relative permittivity of the polymer material used as the polymer matrix 38 is 10 or more at 25°C. Accordingly, when a voltage is applied to the polymer composite piezoelectric body, a higher electric field is required for the piezoelectric particles in the polymer matrix, so a large amount of deformation can be expected. However, on the other hand, in consideration of ensuring good moisture resistance, etc., at 25° C., the number of polymer materials is preferably 10 or less.

Examples of polymer materials satisfying such conditions include cyanoethylated polyvinyl alcohol (cyanoethylated PVA), polyvinyl acetate, polyvinylidene chloride acrylonitrile, polystyrene-vinyl polyvinyl alcohol, and polyvinyl chloride. Isoprene block copolymer, polyvinyl methyl ketone and polybutyl methacrylate, etc. In addition, commercially available items such as Hibler 5127 (manufactured by KURARAY CO., LTD.) can also be preferably used as such polymer materials.

As the polymer material constituting the polymer matrix 38, it is preferable to use a polymer material having a cyanoethyl group, and it is particularly preferable to use cyanoethylated PVA. That is, in the piezoelectric acoustic film 24, it is preferable to use a polymer material having a cyanoethyl group as the polymer matrix 38 for the piezoelectric layer 26, and it is particularly preferable to use cyanoethylated PVA. In the following description, the above-mentioned polymer materials represented by cyanoethylated PVA are collectively referred to as "polymer materials having viscoelasticity at room temperature".

In addition, these polymer materials having viscoelasticity at normal temperature may be used alone or in combination (mixed) in plural.

In the piezoelectric acoustic film 24, the polymer matrix 38 of the piezoelectric layer 26 may use a plurality of polymer materials in combination as necessary. That is, for the purpose of adjusting dielectric properties or mechanical properties, etc., in addition to the polymer material having viscoelasticity at the above normal temperature, other dielectric materials can also be added to the polymer matrix 38 constituting the polymer composite piezoelectric body as required. Electrical polymer materials.

As dielectric polymer materials that can be added, polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, polyvinylidene fluoride- Fluorine-based polymers such as trifluoroethylene copolymer and polyvinylidene fluoride-tetrafluoroethylene copolymer, vinylidene-vinyl ester copolymer, cyanoethyl cellulose, cyanoethyl hydroxy sucrose, cyanoethyl hydroxy fiber cyanoethyl hydroxyfullerene, cyanoethyl methacrylate, cyanoethyl acrylate, cyanoethyl hydroxyethyl cellulose, cyanoethyl amylose, cyanoethyl hydroxypropyl cellulose, cyanoethyl Dihydroxypropyl cellulose, cyanoethyl hydroxypropyl amylose, cyanoethyl polyacrylamide, cyanoethyl polyethylacrylate, cyanoethyl fullerene, cyanoethyl polyhydroxymethylene, cyanide Polymers with cyano or cyanoethyl groups such as ethyl glycidyl fullerene, cyanoethyl sucrose and cyanoethyl sorbitol, and synthetic rubbers such as nitrile rubber and chloroprene rubber. Among them, polymer materials having cyanoethyl groups are preferably used. In addition, in the polymer matrix 38 of the piezoelectric layer 26, the dielectric polymer material is not limited to one kind, and plural kinds may be added.

In addition, for the purpose of adjusting the glass transition point Tg of the polymer matrix 38, in addition to the dielectric polymer material, vinyl chloride resin, polyethylene, polystyrene, methacrylic resin, polybutylene, isobutylene, etc. may be added. Thermoplastic resins and thermosetting resins such as phenolic resins, urea resins, melamine resins, alkyd resins, and mica. Furthermore, for the purpose of improving the tackiness, tackifiers such as rosin esters, rosin, terpenes, terpene phenols, and petroleum resins may be added.

In the polymer matrix 38 of the piezoelectric layer 26, there is no limit to the amount of the polymer material other than the polymer material having viscoelasticity at room temperature, and the proportion of the polymer matrix 38 is set to 30% by mass. Below % is better. In this way, the properties of the added polymer material can be exhibited without damaging the viscoelasticity relaxation mechanism in the polymer matrix 38. Therefore, the high dielectric constant, the improvement of heat resistance, and the interaction between the piezoelectric particles 40 and the electrode layer can be realized. Better results can be obtained in aspects such as improved adhesion.

The polymer composite piezoelectric system to be the piezoelectric layer 26 includes piezoelectric particles 40 in such a polymer matrix. The piezoelectric particles 40 are dispersed in the polymer matrix, preferably uniformly (approximately uniformly). The piezoelectric particles 40 are preferably composed of ceramic particles having a perovskite-type or wurtzite-type crystal structure. Examples of ceramic particles constituting piezoelectric particles 40 include lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), barium titanate (BaTiO ₃ ), zinc oxide (ZnO), and barium titanate and iron Bismuth bismuth (BiFe ₃ ) solid solution (BFBT), etc.

The particle size of the piezoelectric particles 40 may be appropriately selected according to the size and application of the piezoelectric acoustic film 24 . The particle size of the piezoelectric particles 40 is preferably 1 to 10 μm. By setting the particle size of the piezoelectric particles 40 within the above-mentioned range, a favorable result can be obtained in terms of both high piezoelectric characteristics and flexibility.

In the piezoelectric acoustic film 24, the quantitative ratio between the polymer matrix 38 and the piezoelectric particles 40 in the piezoelectric layer 26 depends only on the size and thickness of the piezoelectric acoustic film 24 in the plane direction, the application of the piezoelectric acoustic film 24, The characteristics and the like required for the piezoelectric acoustic film 24 may be appropriately set. The volume fraction of the piezoelectric particles 40 in the piezoelectric layer 26 is preferably 30 to 80%, more preferably 50 to 80%. By setting the amount ratio of the polymer matrix 38 to the piezoelectric particles 40 within the above-mentioned range, a better result can be obtained in terms of both high piezoelectric characteristics and flexibility.

In addition, in the piezoelectric acoustic film 24, the thickness of the piezoelectric body layer 26 is not limited, as long as it is appropriate according to the size of the piezoelectric acoustic film 24, the application of the piezoelectric acoustic film 24, the characteristics required for the piezoelectric acoustic film 24, etc. can be set locally. The thickness of the piezoelectric layer 26 is preferably from 8 to 300 μm, more preferably from 8 to 200 μm, still more preferably from 10 to 150 μm, and most preferably from 15 to 100 μm. By setting the thickness of the piezoelectric layer 26 within the above-mentioned range, a favorable result can be obtained in terms of ensuring rigidity, appropriate flexibility, and the like.

The piezoelectric layer 26 is preferably polarized in the thickness direction. The polarization treatment will be described in detail later.

In addition, in the piezoelectric acoustic film 24, the piezoelectric body layer 26 is not limited to the one described above, and the polymer matrix 38 composed of a polymer material having viscoelasticity at room temperature, such as cyanoethylated PVA, contains a piezoelectric material. The bulk particle 40 is a polymer composite piezoelectric body. That is, in the piezoelectric acoustic film 24 , various known piezoelectric layers used for piezoelectric films can be used for the piezoelectric layer 26 .

As an example, the same compressive force can also be used in a substrate comprising the above-mentioned dielectric polymer materials such as polyvinylidene fluoride, vinylidene chloride-tetrafluoroethylene copolymer, and vinylidene chloride-trifluoroethylene copolymer. Electrode particle 40 is a polymer composite piezoelectric body, a piezoelectric layer made of polyvinylidene fluoride, a piezoelectric layer made of fluororesin other than polyvinylidene fluoride, and a film made of poly-L-lactic acid. And the piezoelectric layer of the film composed of poly-D lactic acid, etc. However, as described above, it is better to follow the method of obtaining excellent acoustic characteristics that can be obtained with hard motion for vibrations of 20 Hz to 20 kHz and soft motions for slower vibrations below a few Hz. Considering the coiled piezoelectric acoustic film 24 of the screen body 50 with excellent flexibility, etc., in the polymer matrix 38 composed of a polymer material having viscoelasticity at room temperature, such as cyanoethylated PVA, piezoelectric A polymer composite piezoelectric body of bulk particles 40 can be preferably used as the piezoelectric body layer 26 .

The piezoelectric acoustic film 24 shown in FIG. 8 has the second electrode layer 30 on one surface of the piezoelectric body layer 26 and has the second protective layer 34 on the surface of the second electrode layer 30 . Moreover, the first electrode layer 28 is provided on the other surface of the piezoelectric layer 26 , and the first protective layer 32 is provided on the surface of the first electrode layer 28 . In the piezoelectric acoustic film 24 , the first electrode layer 28 and the second electrode layer 30 form an electrode pair. In other words, the laminated film constituting the piezoelectric acoustic film 24 has both sides of the piezoelectric body layer 26 sandwiched between the electrode pair, that is, the first electrode layer 28 and the second electrode layer 30 , and is further formed by the first protective layer 32 and the second protective layer 34 . It is formed by clamping. In this way, the region sandwiched between the first electrode layer 28 and the second electrode layer 30 is driven according to the applied voltage.

In addition, in the present invention, first and second among the first electrode layer 28 and the second electrode layer 30 etc. are added for convenience of description of the piezoelectric acoustic film 24 . Therefore, the first and second terms in the piezoelectric acoustic film 24 have no technical significance, and are irrelevant to the actual use state.

In addition to these layers, the piezoelectric acoustic film 24 may have an adhesive layer for attaching the electrode layer and the piezoelectric body layer 26 and an adhesive layer for attaching the electrode layer and the protective layer. The patch can be an adhesive or an adhesive. In addition, the same material as the polymer matrix 38 , which is a polymer material from which the piezoelectric particles 40 are removed from the piezoelectric layer 26 , can also be preferably used for the adhesive agent. In addition, the sticking layer may be provided on both the first electrode layer 28 side and the second electrode layer 30 side, or may be provided on only one of the first electrode layer 28 side and the second electrode layer 30 side.

In the piezoelectric acoustic film 24, the first protective layer 32 and the second protective layer 34 cover the first electrode layer 28 and the second electrode layer 30, and at the same time serve to impart appropriate rigidity and mechanical strength to the piezoelectric layer 26. . That is, in the piezoelectric acoustic film 24, the piezoelectric layer 26 including the polymer matrix 38 and the piezoelectric particles 40 exhibits very excellent flexibility for slow bending deformation, but there is a rigidity or insufficient mechanical strength depending on the application. Condition. The piezoelectric acoustic film 24 is provided with the first protective layer 32 and the second protective layer 34 to compensate for this situation. The first protective layer 32 and the second protective layer 34 have the same configuration except for the arrangement position. Therefore, in the following description, when there is no need to distinguish the first protective layer 32 and the second protective layer 34, both members are collectively referred to as a protective layer.

The protective layer is not limited, and various sheets can be used. As an example, various resin films are preferably illustrated. Among them, polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyphenylene sulfide, etc. (PPS), polymethylmethacrylate (PMMA), polyetherimide (PEI), polyimide (PI), polyamide (PA), polyethylene naphthalate (PEN), three Resin films composed of acetyl cellulose (TAC) and cyclic olefin resins are preferably used.

The thickness of the protective layer is also not limited. In addition, the thicknesses of the first protective layer 32 and the second protective layer 34 are basically the same, but may be different. If the rigidity of the protective layer is too high, not only the expansion and contraction of the piezoelectric layer 26 will be restrained, but also the flexibility will be impaired. Therefore, unless mechanical strength or good handling properties as a sheet are required, the thinner the protective layer is, the more advantageous it is.

When the thicknesses of the first protective layer 32 and the second protective layer 34 are each less than twice the thickness of the piezoelectric layer 26 , favorable results can be obtained in terms of ensuring rigidity and appropriate flexibility. For example, when the thickness of the piezoelectric layer 26 is 50 μm and the first protective layer 32 and the second protective layer 34 are made of PET, the thicknesses of the first protective layer 32 and the second protective layer 34 are preferably 100 μm or less. , 50 μm or less is more preferable, and it is more preferable to set it as 25 μm or less.

In addition, in the piezoelectric acoustic film 24, the first protective layer 32 and the second protective layer 34 are provided as a preferred mode and are not essential components. That is, in the electroacoustic transducer of the present invention, the piezoelectric acoustic film 24 may only have the first protective layer 32, or may only have the second protective layer 34, or may not have the first protective layer. 32 and the second protective layer 34. However, considering the strength, handleability, protection of electrode layers, etc. of the piezoelectric acoustic film 24, it is preferable that the piezoelectric acoustic film has both the first protective layer 32 and the second protective layer 34 as shown in the illustrated example.

In the piezoelectric acoustic film 24 , the first electrode layer 28 is formed between the piezoelectric layer 26 and the first protective layer 32 , and the second electrode layer 30 is formed between the piezoelectric layer 26 and the second protective layer 34 . The first electrode layer 28 and the second electrode layer 30 are provided to apply an electric field to the piezoelectric acoustic film 24 (piezoelectric layer 26 ).

The first electrode layer 28 and the second electrode layer 30 are basically the same except for the position difference. Therefore, in the following description, when there is no need to distinguish between the first electrode layer 28 and the second electrode layer 30, the two members are also collectively referred to as electrode layers.

In the piezoelectric acoustic film, the material for forming the electrode layer is not limited, and various conductors can be used. Specifically, carbon, palladium, iron, tin, aluminum, nickel, platinum, gold, silver, copper, chromium, molybdenum, alloys thereof, indium tin oxide, and PEDOT/PPS (polyethylenedioxythiophene-polyethylene) are exemplified. Styrene sulfonic acid) and other conductive polymers. Among these, copper, aluminum, gold, silver, platinum, and indium tin oxide are preferably exemplified. Among them, copper is more preferable from the viewpoints of conductivity, cost, and flexibility.

Also, the method of forming the electrode layer is not limited, and various vapor deposition methods (vacuum film formation methods) such as vacuum evaporation and sputtering, film formation by electroplating, or a method of attaching foil formed of the above materials can be used. , coating method and other known methods. Among them, for reasons such as securing the flexibility of the piezoelectric acoustic film 24 , copper and aluminum films formed by vacuum evaporation are particularly preferably used as electrode layers. Among them, it is particularly preferable to use a thin film of copper formed by vacuum evaporation.

The thicknesses of the first electrode layer 28 and the second electrode layer 30 are not limited. In addition, the thicknesses of the first electrode layer 28 and the second electrode layer 30 are basically the same, but may be different. However, similarly to the protective layer described above, if the rigidity of the electrode layer is too high, not only the expansion and contraction of the piezoelectric layer 26 will be restricted, but also the flexibility will be impaired. Therefore, as long as the resistance does not become too high, it is more advantageous that the electrode layer is thinner.

In the piezoelectric acoustic film 24, it is preferable that the product of the thickness of the electrode layer and the Young's modulus is lower than the product of the thickness of the protective layer and the Young's modulus, since the flexibility will not be seriously impaired. For example, when the protective layer is PET (Young's modulus: about 6.2GPa) and the electrode layer is made of copper (Young's modulus: about 130GPa), if the thickness of the protective layer is 25μm, the electrode layer The thickness is preferably 1.2 μm or less, more preferably 0.3 μm or less, and particularly preferably 0.1 μm or less.

The piezoelectric acoustic film 24 has a piezoelectric body layer 26 sandwiched between a first electrode layer 28 and a second electrode layer 30, and furthermore, as a preferred embodiment, the laminate is sandwiched between a first protective layer 32 and a second protective layer 34. The composition. Such a piezoelectric acoustic film 24 preferably has a maximum value of loss tangent (Tan δ) at a frequency of 1 Hz obtained by dynamic viscoelasticity measurement at normal temperature of 0.1 or more. In this way, even if the piezoelectric acoustic film 24 is continuously subjected to relatively slow and large bending deformation below a few Hz from the outside, the strain energy can be effectively diffused to the outside as heat, so that the deformation between the polymer matrix and the piezoelectric film 24 can be prevented. Cracks occur at the interface of bulk particles.

The piezoelectric acoustic film 24 is preferably as follows, that is, the storage elastic coefficient (E') at a frequency of 1 Hz based on dynamic viscoelasticity measurement is 10-30 GPa at 0°C and 1-10 GPa at 50°C. Thereby, the piezoelectric acoustic film 24 can have a large frequency dispersion in the storage elastic coefficient (E') at room temperature. That is, it can operate relatively hard for vibrations of 20 Hz to 20 kHz, and can appear relatively soft for vibrations of several Hz or less.

In addition, it is preferable that the piezoelectric acoustic film 24 is such that the product of the thickness and the storage elastic coefficient (E') at a frequency of 1 Hz based on dynamic viscoelasticity measurement is 1.0×10 ⁶ to 2.0× 10 ⁶ N/m, 1.0×10 ⁵ to 1.0×10 ⁶ N/m at 50°C. Accordingly, the piezoelectric acoustic film 24 can have appropriate rigidity and mechanical strength within a range that does not impair flexibility and acoustic characteristics.

Furthermore, it is preferable that the piezoelectric acoustic film 24 has a loss tangent (Tanδ) of 0.05 or more at a frequency of 1 kHz at 25° C. in the main curve obtained from dynamic viscoelasticity measurement.

Hereinafter, an example of a method of manufacturing the piezoelectric acoustic film 24 will be described with reference to FIGS. 9 to 11 . First, a laminate 42b in which the second electrode layer 30 is formed on the surface of the second protective layer 34 schematically shown in FIG. 9 is prepared. Furthermore, a laminate 42a in which the first electrode layer 28 is formed on the surface of the first protective layer 32 schematically shown in FIG. 11 is prepared.

The laminate 42 b can be produced by forming a copper thin film or the like on the surface of the second protective layer 34 as the second electrode layer 30 by vacuum evaporation, sputtering, electroplating, or the like. Similarly, the laminated body 42a can be produced by forming a copper thin film or the like on the surface of the first protective layer 32 as the first electrode layer 28 by vacuum evaporation, sputtering, plating, or the like. Alternatively, a commercially available sheet in which a copper thin film or the like is formed on a protective layer may be used as the laminate 42b and/or the laminate 42a. The laminated body 42b and the laminated body 42a may be the same or different.

In addition, when the protective layer is very thin and the handleability is poor, a protective layer with a spacer (temporary support) can be used as needed. In addition, PET or the like having a thickness of 25 to 100 μm can be used as the separator. What is necessary is just to remove a separator after thermocompression bonding of an electrode layer and a protective layer.

Next, as schematically shown in FIG. 10 , the piezoelectric layer 26 is formed on the second electrode layer 30 of the layered body 42b to fabricate a piezoelectric layered body 46 in which the layered body 42b and the piezoelectric layer 26 are stacked.

The piezoelectric layer 26 may be formed by a known method for the piezoelectric layer 26 . For example, in the piezoelectric layer (polymer composite piezoelectric layer) in which piezoelectric particles 40 are dispersed in the polymer matrix 38 shown in FIG. 8 , it is fabricated as follows as an example. First, a polymer material such as cyanoethylated PVA is dissolved in an organic solvent, and piezoelectric particles 40 such as PZT particles are added and stirred to prepare a paint. The organic solvent is not limited, and various organic solvents such as dimethylformamide (DMF), methyl ethyl ketone, and cyclohexanone can be used. After the laminated body 42 b is prepared, and the paint is prepared, the paint is casted (coated) on the laminated body 42 b, and the organic solvent is evaporated and dried. Thereby, as shown in FIG. 10 , a piezoelectric laminate 46 having the second electrode layer 30 on the second protective layer 34 and laminating the piezoelectric layer 26 on the second electrode layer 30 is fabricated.

The casting method of the paint is not limited, and any known method (coating device), such as a bar coater, a slide coater, and a doctor knife, can be used. Alternatively, if the polymer material can be heated and melted, a molten material in which piezoelectric particles 40 are added can be produced by heating and melting the polymer material, and the molten material shown in FIG. 3 can be formed by extrusion molding or the like. The laminated body 42b shown is extruded into a sheet shape and cooled to produce a piezoelectric laminated body 46 as shown in FIG. 9 .

In addition, as mentioned above, in the piezoelectric acoustic film 24 , in addition to the polymer material having viscoelasticity at room temperature, a polymer piezoelectric material such as PVDF may be added to the polymer matrix 38 . When adding these piezoelectric polymer materials to the polymer matrix 38, it is only necessary to dissolve the piezoelectric polymer materials added to the above-mentioned paint. Alternatively, it is sufficient to add the piezoelectric polymer material to be added to the viscoelastic polymer material that has been heated and melted at room temperature for heating and melting.

After the piezoelectric layer 26 is formed, a rolling treatment may be performed as necessary. The calendering treatment may be performed once or multiple times. As is well known, the calendering treatment refers to a treatment for flattening or the like by pressing while heating the surface to be treated with a hot press or a heating roll.

In addition, the piezoelectric layer 26 of the piezoelectric laminate 46 having the second electrode layer 30 on the second protective layer 34 and the piezoelectric layer 26 formed on the second electrode layer 30 is polarized. . The method of polarization treatment of the piezoelectric layer 26 is not limited, and a known method can be used. For example, electric field polarization in which a DC electric field is directly applied to an object to be polarized is exemplified. In addition, in the case of performing electric field polarization, the first electrode layer 28 may be formed before the polarization treatment, and the electric field polarization treatment may be performed using the first electrode layer 28 and the second electrode layer 30 . In addition, when the piezoelectric acoustic film 24 is produced, the polarization treatment performs polarization not only in the plane direction but also in the thickness direction of the piezoelectric layer 26 .

Next, as schematically shown in FIG. 11 , the previously prepared laminate 42 a is laminated on the piezoelectric layer 26 side of the piezoelectric laminate 46 with the first electrode layer 28 facing the piezoelectric layer 26 . Furthermore, this laminated body is sandwiched between the first protective layer 32 and the second protective layer 34, and thermocompression bonding is performed using a heat press device, a heating roller, etc., so that the piezoelectric laminated body 46 and the laminated body 42a are bonded together. In this way, the piezoelectric body layer 26, the first electrode layer 28 and the second electrode layer 30 provided on both surfaces of the piezoelectric body layer 26, and the first protective layer 32 and the second protective layer 34 formed on the surface of the electrode layer were produced. The piezoelectric sound film 24.

The piezoelectric acoustic film 24 manufactured by performing such manufacturing steps is polarized not only in the surface direction but also in the thickness direction, and high piezoelectric characteristics can be obtained even without stretching after the polarization processing. Therefore, the piezoelectric acoustic film 24 has no in-plane anisotropy in piezoelectric characteristics, and expands and contracts isotropically in all directions in the plane direction when a driving voltage is applied.

Lead-out electrodes for electrical connection to external devices such as a power supply are connected to the electrode layer of the piezoelectric acoustic film 24 , and connection wiring 64 having a speaker amplifier connection portion 64 a is connected to the lead-out wiring.

In the projection screen 10 of the present invention, the method of connecting the electrode layer and the lead-out electrodes is not limited, and various methods can be used. As an example, a method of inserting a sheet-shaped lead-out electrode between the electrode layer and the piezoelectric layer, and connecting the connection wiring 64 to the lead-out electrode is exemplified. In addition, an extraction electrode may be interposed between the electrode layer and the protective layer. Alternatively, the connection wiring 64 may be inserted directly between the electrode layer and the piezoelectric layer, or between the electrode layer and the protective layer. As another method, a method is exemplified in which a through hole is formed in the protective layer, an electrode connection member made of a metal paste such as silver paste is provided to fill the through hole, and an extraction electrode is provided on the electrode connection member. As another method, a method is exemplified in which a part of the protective layer and the electrode layer protrudes from the piezoelectric layer in the direction along the plane, and the extraction electrode is connected to the protruding electrode layer. In addition, the connection between the extraction electrode and the electrode layer may be performed by a known method such as a method using a metal paste such as silver glue, a method using solder, or a method using a conductive adhesive. As a suitable electrode extraction method, the method described in Unexamined-Japanese-Patent No. 2014-209724, the method described in Unexamined-Japanese-Patent No. 2016-015354, etc. are illustrated.

The piezoelectric acoustic film 24 is attached to the screen body 50 by an adhesive material (not shown). In the present invention, various known ones can be used as the sticking material as long as the screen main body 50 and the piezoelectric acoustic film 24 can be stuck together. Therefore, the adhesive material may be a layer composed of an adhesive (adhesive material) that has fluidity when pasted and then becomes solid, or may be a soft solid that is gel-like (rubber-like) when pasted and then becomes solid. The layer composed of an adhesive (adhesive material) also maintaining a gel state may be a layer composed of a material having characteristics of both the adhesive and the adhesive. In addition, the patch may be formed by applying a fluid patch such as a liquid, or may be formed using a sheet-like patch.

In the projection screen 10 , the piezoelectric acoustic film 24 is formed by sandwiching the piezoelectric body layer 26 between the first electrode layer 28 and the second electrode layer 30 . The piezoelectric layer 26 preferably has piezoelectric particles 40 in the polymer matrix 38 . The piezoelectric layer 26 is preferably formed by dispersing piezoelectric particles 40 in the polymer matrix 38 .

If a voltage corresponding to the sound signal (acoustic signal) is applied to the second electrode layer 30 and the first electrode layer 28 of the piezoelectric acoustic film 24 having such a piezoelectric layer 26, the piezoelectric particles will move according to the applied voltage. 40 stretches towards the polarization direction. As a result, the piezoelectric acoustic film 24 (piezoelectric layer 26 ) shrinks in the thickness direction. At the same time, due to the relationship of Poisson's ratio, the piezoelectric acoustic film 24 also expands and contracts in the plane direction. This expansion and contraction is about 0.01 to 0.1%. As described above, the thickness of the piezoelectric layer 26 is preferably about 10 to 300 μm. Therefore, the maximum expansion and contraction in the thickness direction is only about 0.3 μm, which is very small. In contrast, the piezoelectric acoustic film 24 , that is, the piezoelectric layer 26 has a dimension significantly larger than its thickness in the plane direction. Therefore, for example, if the length of the piezoelectric acoustic film 24 is 20 cm, the piezoelectric acoustic film 24 expands and contracts by a maximum of about 0.2 mm by applying a voltage.

The screen main body 50 is bent by expansion and contraction of the piezoelectric acoustic film 24, and as a result, the entire surface of the screen main body 50 vibrates in the thickness direction. In other words, the thickness direction is a direction perpendicular to the surface direction of the screen body 50 . The screen main body 50 outputs sound by the vibration in the thickness direction. That is, the screen body 50 vibrates according to the magnitude of the voltage (driving voltage) applied to the piezoelectric acoustic film 24 , and outputs a sound corresponding to the driving voltage applied to the piezoelectric acoustic film 24 .

Also, as described above, in the piezoelectric acoustic film 24, the thickness of the piezoelectric layer 26 is preferably about 300 μm at the maximum. In addition, the piezoelectric acoustic acoustic film 24 using the polymer composite piezoelectric body, that is, the piezoelectric body layer 26 has very good flexibility. Therefore, the piezoelectric acoustic film 24 is very thin and has good flexibility. Therefore, when the screen body 50 is rolled up by using the piezoelectric acoustic film 24 , the piezoelectric acoustic film 24 preferably follows the winding of the screen body 50 . As a result, the screen main body 50 to which the piezoelectric acoustic film 24 is attached can be rolled up preferably.

In addition, in the projection screen 10 of the present invention, the piezoelectric acoustic film is not limited to a single layer as shown in the figure, and a plurality of piezoelectric acoustic films 24 may be laminated. In this regard, the above-mentioned various piezoelectric acoustic films are the same except for the piezoelectric acoustic film 24 . When laminating a plurality of piezoelectric acoustic films 24, it is possible to laminate a plurality of sheets of piezoelectric acoustic films 24 that remove sheets, or, for example, as described in International Publication No. 2020/095812, etc., one piezoelectric acoustic film 24 may be laminated. The film 24 is folded back once or more to form a plurality of layers. As described above, the piezoelectric acoustic film 24 is very thin and has good flexibility. Therefore, even a laminate in which a plurality of layers is laminated has good flexibility and can be wound up preferably.

In addition, in the present invention, when a plurality of piezoelectric acoustic films 24 are laminated, it is preferable to stick the adjacent piezoelectric acoustic films 24 by lamination with an adhesive agent. The adhesive (adhesive layer) can be an adhesive that is fluid when pasted and then becomes solid, or it can be a soft solid that is gel-like (rubber-like) when pasted and then remains gel. The adhesive in the shape of the state may also be composed of a material having the characteristics of both the adhesive and the adhesive. However, from the viewpoint of being able to transmit the expansion and contraction of the laminated piezoelectric acoustic film 24 without loss and preferably, it is preferable to use an adhesive that finally becomes solid for the patch.

As described above, the projection screen 10 of the present invention is schematically shown in the sectional view (right side) of FIG. 1 and FIG. The projection screen 10 of the present invention has such a soundproof sheet 59 so that the anti-phase sound originating from the back side of the screen body 50 surrounds the projection surface side and prevents a part of the sound output from the projection surface side from canceling each other. .

As described above, in the screen in which the piezoelectric acoustic film is provided on the rear surface of the projection surface, the entire surface of the screen is vibrated by the piezoelectric acoustic film, and sound is output by the vibration of the screen. Therefore, the screen is in a state where sound is output from the screen, and sound with a high sense of presence can be output. However, in this screen, since the entire surface of the screen vibrates, the sound of the reverse phase is also output from the rear side and surrounds the projection surface side. Since part of the anti-phase sound cancels out the sound output on the projection surface side, the output of the sound is reduced when the video is viewed on the projection surface side.

On the other hand, the projection screen 10 of the present invention covers the back side of the screen main body 50 and provides the soundproof sheet 59 . In the illustrated example, the soundproof sheet 59 is attached to the first supporting member 52 and the second supporting member 54 by Velcro, and covers the entire surface of the screen main body 50 .

The projection screen 10 of the present invention shields the anti-phase sound output from the back side of the screen body 50 with the sound-insulation sheet 59 by having such a sound-insulation sheet 59, so as to prevent the anti-phase sound output from the back side from surrounding. projection side. As a result, according to the projection screen 10 of the present invention, when viewed from the projection side of the projection screen 10, sound pressure drops are suppressed by canceling the sound, so that appropriate audio and video can be viewed and listened to.

In the projection screen 10 of the present invention, the soundproof sheet 59 is not limited, and various known sheet-like objects can be used. As an example, various sheets used as the screen main body 50 composed of the above-mentioned resin such as vinyl chloride, paper such as Japanese paper, cloth such as school cloth, etc. are illustrated. In addition, when the screen body 50 is used for the soundproof sheet 59, the screen body 50 and the soundproof sheet 59 may be the same or different. In addition, as the sound-proof sheet 59, a sheet-shaped object made of a porous body such as rubber or urethane foam, a non-woven fabric such as felt, or the like can also be used.

In the projection screen 10 of the present invention, as shown in the sectional view of FIG. 1 , it is preferable that there is a space between the screen body 50 , the piezoelectric acoustic film 24 and the sound insulation sheet 59 . In other words, in the projection screen 10 of the present invention, it is preferable that the screen body 50 and the piezoelectric acoustic film 24 are not in contact with the sound insulation sheet 59 .

If the screen body 50 and/or the piezoelectric acoustic film 24 is in contact with the sound insulation sheet 59, the sound insulation sheet 59 will also vibrate together. As a result, the anti-phase sound generated from the back side of the screen main body 50 cannot be prevented from surrounding to the projection surface side, resulting in canceling part of the sound output from the projection surface side. In contrast, by separating the screen body 50 and the piezoelectric acoustic film 24 from the sound insulation sheet 59 , it is possible to better prevent the sound insulation sheet 59 from vibrating so as to prevent anti-phase sound from surrounding the projection surface.

There is no limit to the size of the interval between the screen body 50 and the piezoelectric acoustic film 24 and the sound insulation sheet 59, as long as the screen body 50 and the piezoelectric acoustic film 24 are separated from the sound insulation sheet 59 in the state of outputting sound through the vibration of the screen body 50 status. Therefore, regarding the distance between the screen body 50, the piezoelectric acoustic film 24 and the sound-insulating sheet 59, the screen body 50, the piezoelectric acoustic film 24, and the sound-insulating sheet are appropriately set in a state in which the screen body 50, the piezoelectric acoustic film 24, and the sound-insulating sheet are output in accordance with the device configuration and the like. 59 intervals without contact.

Also, if the screen body 50 and the piezoelectric acoustic film 24 are not in contact with the sound-insulating sheet 59, the sound-insulating sheet 59 can be fixed in a relaxed state without tension even if it is stretched with a certain degree of tension.

It is better that the sound insulation sheet 59 can be assembled and disassembled. That is, it is preferable that the projection screen 10 has a mechanism for attaching and detaching the soundproof sheet. In the illustrated example, as described above, the soundproof sheet 59 is detachably fixed to the first support member 52 and the second support member 54 by Velcro.

As described above, in the projection screen 10, when not in use, the screen main body 50 is detached from the stretching mechanism 56 together with the first supporting member 52 and the second supporting member 54, and is wound up between the first supporting member 52 and the second supporting member 54. /or the second support member 54 .

When performing this winding, the screen main body 50 and the sound insulating sheet 59 need to be wound together without removing the sound insulating sheet 59 . When the screen body 50 and the sound insulation sheet 59 are rolled up together, it is not easy to be rolled up. Not only that, depending on the rolling method, it may cause inconveniences such as wrinkles, breakage, and damage to the screen body 50 . On the other hand, by making the soundproof sheet 59 detachable, the screen body 50 and the soundproof sheet 59 can be rolled up separately, and the winding of both is easy, and it is also possible to preferably prevent the screen body 50 from Inconvenience such as wrinkles on the skin.

In the projection screen 10, there is no limit to the method of making the soundproof sheet 59 detachable, that is, the method of using Velcro for the detachable mechanism, and various known methods of making the sheet-like objects detachable can be used. As an example, a method of using a hook (hook-shaped member) and a ring (hole) hooked to the hook, a method of using a magnet, and a method of joining with sheet-shaped unevenness are exemplified.

In the projection screen 10 of the illustrated example, the soundproof sheet 59 is provided so as to cover the entire rear surface of the screen main body 50 . However, the present invention is not limited thereto, and the soundproof sheet 59 may cover a part of the rear surface of the screen body 50 . However, it is preferable that the soundproof sheet 59 covers the entire back surface of the screen body 50 from the viewpoint of preventing the anti-phase sound generated from the back side of the screen body 50 from surrounding the projection surface.

The projection screen of the present invention has been described in detail above, but the present invention is not limited to the above-mentioned examples, and various improvements and changes are possible without departing from the gist of the present invention. [Example]

Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention. In addition, this invention is not limited to this Example, Unless it deviates from the gist of this invention, the material, usage-amount, ratio, process content, process procedure etc. which are shown in the following example can be changed suitably.

[Production of piezoelectric acoustic film] A piezoelectric acoustic film was fabricated by the method shown in FIGS. 9 to 11 . First, cyanoethylated PVA (manufactured by CR-V Shin-Etsu Chemical Co., Ltd.) was dissolved in dimethylformamide (DMF) at the following composition ratio. Then, to this solution, PZT particles were added as piezoelectric particles at the following composition ratio, and stirred with a propeller mixer (rotational speed: 2000 rpm) to prepare a coating material for forming a piezoelectric layer. ・PZT particles 300 parts by mass ·Cyanoethylated PVA...30 parts by mass ·DMF················· 70 parts by mass In addition, PZT particles are used so that Zr=0.52 mole and Ti=0.48 mole relative to Pb=1 mole, and Pb oxide, Zr oxide, and Ti, which are the main components, are oxidized at 800°C with a ball mill. The mixed powder obtained by wet mixing the powder of the product is calcined for 5 hours and then pulverized.

On the other hand, a sheet in which a 0.1-μm-thick copper thin film was vacuum-deposited on a 4-μm-thick PET film was prepared. That is, in this example, the first electrode layer and the second electrode layer are copper vapor-deposited films with a thickness of 0.1 m, and the first protective layer and the second protective layer are PET films with a thickness of 4 μm. On the second electrode layer (copper-deposited thin film) of the sheet, a coating for forming a piezoelectric layer prepared in advance was applied using a diagonal die coater. In addition, the coating material was applied so that the film thickness of the coating film after drying would be 40 μm. Next, the DMF was evaporated by heating and drying the sheet-coated material on a heating plate at 120°C. In this way, a laminate having a piezoelectric layer (polymer composite piezoelectric layer) having a thickness of 30 μm was produced on the second protective layer made of PET with a second electrode layer made of copper.

The fabricated piezoelectric layer was subjected to polarization treatment in the thickness direction.

On the layered body subjected to the polarization treatment of the piezoelectric layer, the first electrode layer (copper thin film side) faced the piezoelectric layer, and a sheet in which the same thin film was vapor-deposited on the PET film was laminated. Next, by using a laminator, the laminated body and the laminated body of the sheet were thermocompressed at a temperature of 120° C., thereby attaching and bonding the composite piezoelectric body and the first electrode layer. The piezoelectric acoustic film shown.

[Example 1] A vinyl chloride screen body of 1200 x 1600 mm was prepared. Also, the manufactured piezoelectric acoustic film was cut into a square of 120×120 mm. The screen body is divided into two along the longitudinal direction, and a piezoelectric acoustic film is attached to the center of each area. The piezoelectric acoustic film was attached with double-sided adhesive tape. A projection screen as shown in FIGS. 1 and 12 was fabricated using the screen main body to which the piezoelectric acoustic film was attached. The soundproof sheet is the same as that of the screen body, and is fixed to the first support member and the second support member by Velcro, thereby covering the entire surface of the back of the screen body. Therefore, this projection screen has an attachment and detachment mechanism in which the soundproof sheet can be attached and detached. In addition, a space is provided between the piezoelectric acoustic film, the screen main body and the sound insulation sheet so that the two do not come into contact.

[Example 2] A projection screen was produced in the same manner as in Example 1, except that the screen body was divided into four along the short and long sides, and the same piezoelectric acoustic film was attached to each area.

[Example 3] A projection screen was produced in the same manner as in Example 1 except that Japanese paper was used as the screen main body and the soundproof sheet. [Example 4] A projection screen was produced in the same manner as in Example 1 except that canvas was used as the screen main body and the soundproof sheet.

[Example 5] It was produced in the same manner as in Example 1, except that the position of the sound-insulating sheet on the first supporting member and the second supporting member was changed, and no space was provided between the piezoelectric acoustic film and the sound-insulating sheet so that the two could contact each other. Screen for projection.

[Example 6] A projection screen was fabricated in the same manner as in Example 1, except that an adhesive was used and the soundproof sheet was not detachable from the first supporting member and the second supporting member.

[Comparative example 1] A projection screen was produced in the same manner as in Example 1 except that no soundproof sheet was provided.

The following evaluations were performed using the produced projection screen. In addition, as a result of using the projector to project still images and moving images on the screen body, the projected images can be viewed well.

[sound pressure] The sound pressure was measured using a noise meter at a distance of 1m from the screen body and centered on the long and short sides. When measuring sound pressure, 500-20kHz pink noise was input through a constant current amplifier. Voltage regulation is 20Vrms input at 1kHz. The sound pressure level of Example 2 was set to 5 out of 5 stages of evaluation, and the evaluation was made to decrease by 1 every time the sound pressure decreased by 1 dB.

[coilability] As mentioned above, the produced projection screen is disassembled into foot member, stretching mechanism, screen body, first support member and second support member. Furthermore, the sound insulating sheet is detached from the 1st supporting member and the 2nd supporting member about the thing which can attach or detach a sound insulating sheet. Then, the screen body is wound up to the first supporting member. In addition, manual operations are performed during winding, and winding is performed so that winding misalignment does not easily occur and gaps do not occur. After winding up the screen body, it was left to stand for 1 day. Then, the rolled screen body was unrolled, and the presence or absence of wrinkles and wrinkles was evaluated. The case where no wrinkles and wrinkles are confirmed on the screen body is evaluated as A, The case where no wrinkles or creases were observed on the screen body was rated as B. The results are shown in the following tables.

[Table 1] Screen body material Piezoelectric Acoustic Film Acoustic panels evaluate with or without Material space Loading mechanism sound pressure Coilability Example 1 vinyl chloride 2 sheets have vinyl chloride have have 4 A Example 2 vinyl chloride 4 sheets have vinyl chloride have have 5 A Example 3 Japanese paper 2 sheets have Japanese paper have have 4 A Example 4 canvas 2 sheets have canvas have have 4 A Example 5 vinyl chloride 2 sheets have vinyl chloride none have 3 A Example 6 vinyl chloride 2 sheets have vinyl chloride have none 4 B Comparative example 1 vinyl chloride 2 sheets none - - - 2 A In the table, the space refers to the space between the screen body and the piezoelectric sound film and the sound insulation sheet.

As shown in the table above, the projection screen of the present invention having a sound-insulating sheet on the back side of the screen body can obtain higher sound pressure than the conventional projection screen without a sound-insulating sheet, that is, Comparative Example 1. As shown in Embodiment 1 and Embodiment 6, a higher sound pressure can be obtained by providing a space between the screen body and the piezoelectric acoustic film and the sound insulation sheet. In addition, as shown in Embodiment 1 and Embodiment 6, since the soundproof sheet can be detached and the screen can be rolled up when not in use by the attachment and detachment mechanism of the soundproof sheet, even if the screen body is rolled up, wrinkles, etc. can be prevented. Enter the screen. From the above results, the effect of the present invention is obvious. [Industrial availability]

It can be preferably used in the projection of images with audio output.

10: Screen for projection 24: Piezoelectric sound film 26: Piezoelectric layer 28: The first electrode layer 30: The second electrode layer 32: 1st protective layer 34: The second protective layer 38: polymer matrix 40: Piezoelectric particles 42a, 42b: laminated body 46: Piezoelectric laminate 50: screen body 52: The first supporting member 52a: Ontology 52b:C cover shell 52c: through hole 54: The second support member 54a: Ontology 54b:C cover shell 54c: Through hole 56: Stretching mechanism 58: 1st frame member 58a: engaging member 58b: fixed pin 60: 2nd frame member 60a: engaging member 60b: fixed pin 62:Hinge member 62a: Arm 1 62b: 2nd arm 62c, 62d, 62f: axis of rotation 64: Connect wiring 64a: Speaker amplifier connection part 78: Foot member 78a: Upper support member 78b: Lower support member 78c: feet 80: Micro-adjustment mechanism 80a: Adjustable screw

FIG. 1 is a diagram schematically showing an example of the projection screen of the present invention. FIG. 2 is a schematic diagram for explaining the configuration of the projection screen shown in FIG. 1 . FIG. 3 is a schematic diagram for explaining the configuration of the projection screen shown in FIG. 1 . FIG. 4 is a schematic diagram for explaining the configuration of the projection screen shown in FIG. 1 . Fig. 5 is a schematic diagram for explaining the function of the projection screen shown in Fig. 1 . Fig. 6 is a schematic diagram for explaining the function of the projection screen shown in Fig. 1 . Fig. 7 is a schematic diagram for explaining the function of the projection screen shown in Fig. 1 . FIG. 8 schematically shows an example of a piezoelectric acoustic film constituting a piezoelectric element. Fig. 9 is a schematic diagram for explaining an example of a method of manufacturing a piezoelectric acoustic film. Fig. 10 is a schematic diagram for explaining an example of a method of manufacturing a piezoelectric acoustic film. Fig. 11 is a schematic diagram for explaining an example of a method of manufacturing a piezoelectric acoustic film. FIG. 12 is a schematic diagram for explaining the projection screen shown in FIG. 1 .

10: Screen for projection

24: Piezoelectric sound film

50: screen body

52: The first supporting member

54: The second support member

56: Stretching mechanism

58: 1st frame member

59: Sound insulation sheet

60: 2nd frame member

60b: fixed pin

62:Hinge member

62a: Arm 1

62b: 2nd arm

62c, 62d, 62f: axis of rotation

64: Connect wiring

64a: Speaker amplifier connection part

78: Foot member

78a: Upper support member

78b: Lower support member

78c: feet

80: Micro-adjustment mechanism

Claims (9)

A screen for projection, characterized by: The screen body is used to project images; A piezoelectric acoustic film attached to the surface of the aforementioned screen body opposite to the projection surface of the image; and The soundproof sheet is arranged to cover the surface of the screen body opposite to the projection surface. The projection screen as described in claim 1, wherein There is a space between the aforementioned screen body, the aforementioned piezoelectric acoustic film and the aforementioned sound insulation sheet. The projection screen as described in claim 1 or claim 2, wherein The aforementioned sound insulation sheet can be loaded and unloaded. The projection screen as described in claim 1 or claim 2, wherein The aforementioned piezoelectric acoustic film has flexibility. The projection screen as described in claim 1 or claim 2, which has: a first support member supporting one side of the screen body and a second support member supporting a side of the screen body opposite to the side supported by the first support member; and A stretching mechanism for bringing the first support member closer to and apart from the second support member. The projection screen as described in claim 5, which has: The fine adjustment mechanism adjusts the distance between the first support member and the second support member in a state where the first support member and the second support member are separated by the stretching mechanism. The projection screen as described in claim 1 or claim 2, wherein The aforementioned piezoelectric acoustic film has a piezoelectric body layer and electrode layers provided on both surfaces of the piezoelectric body layer. The projection screen as described in claim 7, wherein The aforementioned piezoelectric layer is a polymer composite piezoelectric body having piezoelectric particles in a polymer material. The projection screen as described in claim 8, wherein The polymer material of the polymer composite piezoelectric body is cyanoethylated polyvinyl alcohol.

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