WO2024257668A1 - Automobile interior material including flexible thin speaker - Google Patents

Abstract

The objective of the present invention is to provide an automobile interior material that includes a flexible thin speaker, is made sufficiently thin, and is flexible, and that can consequently be installed in various parts within an automobile, and to provide an automobile including the automobile interior material. The present invention relates to an automobile interior material including a flexible thin speaker, characterized by having a thickness of 30 mm or less and by generating sound pressure through the vibration of a flexible diaphragm, and an automobile including the automobile interior material, wherein a dielectric layer is disposed between a pair of opposing electrically conductive layers, and an electric signal is applied to the pair of electrically conductive layers to cause the pair of conductive layers and the dielectric layer to vibrate integrally, thereby generating sound pressure.

Description

Automotive interior materials including flexible thin speakers

The present invention relates to automotive interior materials that include flexible thin speakers.

As the interior of a car becomes more and more roomy, there is a growing need to use the interior of the car as an acoustic space. To achieve this, it is necessary to reduce noise while the vehicle is running, make the car quieter, and then allow passengers to hear sounds they like with a more realistic feel, so improvements are being made to speaker technology that outputs sound. In particular, speakers must be installed in a limited space inside a car, so technology has been proposed to make the speaker itself smaller by providing space outside the enclosure, as in Patent Document 1 below.

JP 2021-111840 A

However, the technology described in Patent Document 1 is within the category of general speakers, and because they are funnel-shaped, or so-called cone-shaped, or spherical dome-shaped, they cannot be made sufficiently thin, and there is a risk that their light weight and flexibility may be compromised, so they do not fully resolve the limitations on installation space inside a vehicle.

In view of the above-mentioned conventional technology, the problem that the present invention aims to solve is to provide an automobile interior material that includes a flexible, thin speaker that is sufficiently thin and flexible to utilize the interior of the automobile as an acoustic space, and thus can be placed in various spaces inside the automobile.

As a result of extensive research and experimentation to solve the above problems, the inventors unexpectedly discovered that the above problems could be solved by using a flexible material in the vibrating part that generates sound pressure, thereby making the speaker itself thinner, and thus completing the present invention.

That is, the present invention is as follows.
[1] An automobile interior material including a flexible thin speaker having a thickness of 30 mm or less and generating sound pressure by vibrating a flexible diaphragm.
[2] An automobile interior material including the flexible thin speaker described in [1], in which a dielectric layer is disposed between a pair of opposing conductive layers, and when an electrical signal is applied to the pair of conductive layers, the pair of conductive layers and the dielectric layer vibrate together to generate sound pressure.
[3] An automobile interior material including the flexible, thin speaker described in [2], wherein at least one of the pair of conductive layers further comprises an insulating, flexible substrate having breathability or elasticity facing the dielectric layer.
[4] An automobile interior material including the flexible thin speaker described in [2] or [3], wherein at least one of the pair of conductive layers is composed of conductive fibers.
[5] An automobile interior material comprising the flexible thin speaker according to any one of [1] to [4] above, which does not substantially change in frequency characteristics when deformed.
[6] An automobile interior material comprising the flexible thin speaker according to any one of [1] to [5], wherein the flexible thin speaker has a basis weight of 3000 g/m2 ^{or less} .

[7] An automobile interior material comprising the flexible thin speaker according to any one of [1] to [6], wherein the bending resistance of the flexible thin speaker is 300 mm or less.
[8] An automobile interior material comprising the flexible, thin speaker according to any one of [1] to [7], wherein the Young's modulus of the flexible, thin speaker is 10 GPa or less.
[9] An automobile having an automobile interior material including a flexible, thin speaker, in which the automobile interior material including the flexible, thin speaker described in any one of [1] to [8] is attached with an adhesive or pressure-sensitive adhesive to at least one of the seats, headliner, headrest, console, armrest, door trim, carpet, and pillar parts inside the automobile.
[10] An automobile having an automobile interior material including a flexible thin speaker according to any one of [1] to [8], which is arranged in at least one of a headrest, a seat, a seat back, and a pillar portion inside the automobile, and which generates a noise cancellation signal in antiphase with environmental noise.
[11] An automobile having automobile interior material including a flexible thin speaker according to any one of [1] to [8] above, which is arranged in at least one of the headrest, seat surface, and seat back of each passenger's seat, and which is connected to an audio output device by a separate wiring, thereby providing different sounds to each passenger.
[12] An automobile having an automobile interior material including a flexible thin speaker according to any one of [1] to [8], which has a sound output surface and a non-sound output surface, and the non-sound output surface is provided with a sound insulation treatment of 3 dB or more for frequencies from 1000 Hz to 2000 Hz.
[13] A vehicle having an automobile interior material including a flexible thin speaker according to any one of [1] to [8], wherein when the speaker is installed as an automobile interior, the surface farthest from the ears of the person closest to the vehicle is a non-sound output surface.
[14] An automobile having an automobile interior material including the flexible thin speaker according to any one of [1] to [8] above, having a sound directivity ratio of 1.1 or more.
[15] An automobile having automobile interior material including a flexible, thin speaker as described in any one of [1] to [8], which is either a front or front left/right speaker positioned at 0° or ±20° to 35° relative to a line connecting the main occupant experiencing the sound and the front.
[16] An automobile having automobile interior materials including a flexible, thin speaker according to any one of [1] to [8], wherein the flexible, thin speaker is a front speaker positioned at 0° relative to a line connecting the main occupant who experiences the sound and the front of the automobile, and front left and right speakers positioned at ±20° to 35° to the left and right of the line connecting the front of the automobile.
[17] An automobile having automobile interior materials including a flexible, thin speaker according to any one of [1] to [8], wherein the flexible, thin speaker is a front speaker arranged at 0° relative to a line connecting the main occupant who experiences the sound and the front of the automobile, front left and right speakers arranged at ±20° to 35° to the left and right of the front of the automobile based on the line connecting the front of the automobile, and two rear speakers arranged at ±100° to 130° rearward of the line connecting the front of the automobile.
[18] An automobile having automobile interior materials including a flexible, thin speaker according to any of [1] to [8], wherein the flexible, thin speaker is a front speaker arranged at 0° based on a line connecting the main occupant who experiences the sound and the front, front left and right speakers arranged at ±20° to 35° to the left and right of the front based on the line connecting the front, two rear speakers arranged at ±90° to 130° rearward based on the line connecting the front, and one rear speaker arranged 180° rearward based on the line connecting the front.
[19] An automobile having automobile interior materials including a flexible, thin speaker according to any of [1] to [8], wherein the flexible, thin speaker is a front speaker arranged at 0° based on a line connecting the main occupant who experiences the sound and the front, front left and right speakers arranged at ±20° to 35° to the left and right of the front based on the line connecting the front, two rear speakers arranged at ±90° to 120° rearward based on the line connecting the front, and two rear speakers arranged at ±130° to 150° rearward based on the line connecting the front.
[20] An automobile having an automobile interior material including a flexible thin speaker according to any one of [1] to [8], arranged in at least one or more of the front surface of a headrest, the sides of the headrest, the back surface of the headrest, a pillar, a console, and an armrest, so as to occupy 50% or more of the area of each of the following:
[21] An automobile having an automobile interior material including a flexible thin speaker according to any one of [1] to [8], arranged in at least one of a seat cushion, a seat back, a headliner, an instrument panel, and a door trim so as to occupy an area of 10% or more of the area of each of the following:
[22] An automobile having an automobile interior material including the flexible thin speaker according to any one of [1] to [8].

The automobile interior material including the flexible thin speaker of the present invention is thin and lightweight, so it can be installed in various locations inside the automobile, and preferably in at least one location selected from the group consisting of the headrest, seat cushion, seat back, pillar, headliner, instrument panel, door trim, armrest, and console.

1 is a cross-sectional view of an example of a flexible thin speaker included in the automobile interior material of the present embodiment.

Hereinafter, an embodiment of the present invention will be described in detail.
The automobile interior material of this embodiment includes a flexible, thin speaker having a thickness of 30 mm or less and characterized in that it generates sound pressure by vibrating a flexible diaphragm, and preferably includes a flexible, thin speaker in which a dielectric layer is disposed between a pair of opposing conductive layers, and which functions as an electrostatic speaker by applying an electrical signal to the pair of conductive layers, with the pair of conductive layers and the dielectric layer vibrating together to generate sound pressure as a flexible diaphragm.
The term "thin" as used herein means a thickness equivalent to that of the skin used in automobile interiors, and the thickness is 30 mm or less, preferably 20 mm or less, and more preferably 10 mm or less. As illustrated in Fig. 1, when a dielectric layer is disposed between a pair of opposing conductive layers and an insulating flexible base material having air permeability or stretchability is further provided on the opposite side to the dielectric layer, the thickness (t) is the thickness of the integrated dielectric layer.
By having the thickness of the automobile interior material fall within this range, it is possible to arrange the speakers without any particular restrictions even in the limited space inside the automobile. In addition, the lower limit of the thickness is preferably smaller, but from the viewpoint of the workability of the work of upholstering in the automobile interior, a thickness of 1 mm or more is preferable.
Furthermore, the larger area per unit volume allows for greater sound pressure to be output.
The "diaphragm" referred to here may be, for example, a vibrating material made of paper, fiber, polymer material, metal, or ceramic.
The term "automotive interior materials" as used here includes the covering materials and base materials used in automobile seats, headliners, headrests, consoles, armrests, door trim, carpets, pillars, instrument panels, etc. Therefore, it also includes a structure in which a flexible thin speaker is attached to the headrest itself and a cover is wrapped around it as a covering material, with a space between the flexible thin speaker and the covering material.

The "flexibility" of the flexible thin speaker included in the automotive interior material of this embodiment means that it has flexibility equivalent to that of the skin used in automotive interiors, and an example of the index is the bending resistance, which is an index showing the flexibility of the fabric. More specifically, the bending resistance is preferably 300 mm or less, more preferably 250 mm or less, even more preferably 220 mm or less, and particularly preferably 200 mm or less. The bending resistance is measured using a 45° cantilever type testing machine in accordance with JIS-L-1096:2010, Method A (45° cantilever method). By being in this range, it can be arranged to follow complex shapes such as curved surfaces inside the automobile. In addition, by having the bending resistance in the above range, even if the flexible thin speaker body or its fragments come into contact with the passenger in the event of a car collision accident or the like, the traumatic effect tends to be low. The materials that make up the flexible thin speaker will be described later, but by not including hard materials (for example materials with a bending resistance of more than 300 mm) in the materials that make up the flexible thin speaker or automobile interior materials, there is a tendency for the risk of trauma to be reduced.
Traumatic here refers to damage to bodily tissues and organs caused by external forces (mechanical, physical, or chemical).

The flexible thin speaker included in the automobile interior material of this embodiment has a Young's modulus of 10 GPa or less, preferably 5 GPa or less, and more preferably 3 GPa or less. The lower limit of the Young's modulus of the flexible thin speaker is not particularly limited, but can be more than 0 MPa and can be 0.01 MPa or more. By being in this range, even if the flexible thin speaker body comes into contact with the passenger, the traumatic effect tends to be low. The material constituting the flexible thin speaker will be described later, but by not including a hard material (for example, a material with a Young's modulus of more than 10 GPa) in the material constituting the flexible thin speaker or the automobile interior material, the traumatic effect tends to be lower.
In the flexible, thin speaker included in the automobile interior material of this embodiment, a dielectric layer is disposed between a pair of opposing conductive layers, and by applying an electrical signal to the pair of conductive layers, the pair of conductive layers and the dielectric layer vibrate together, thereby generating sound pressure as a flexible diaphragm.

The material used for the conductive layer is not particularly limited as long as it can ensure conductivity in the in-plane direction, but from the viewpoints of ensuring flexibility, breathability, and durability when installed in the vehicle interior, conductive fibers are preferable. The conductive fibers can be at least one type selected from the group consisting of chemical fibers containing metals or carbon black with good conductivity, fibers coated with metals or conductive resins, and metal fibers made from metal fibers. Among these, fibers coated with metals such as titanium, gold, silver, copper, and nickel are preferable from the viewpoints of flexibility and light weight. The coating method is preferably plating or sputtering.

The Young's modulus of the conductive layer of the flexible thin speaker included in the automotive interior material of this embodiment is 10 GPa or less, preferably 5 GPa or less, and more preferably 3 GPa or less. The lower limit of the Young's modulus of the conductive layer of the flexible thin speaker is not particularly limited, but can be greater than 0 MPa and can be 0.01 MPa or more. By having the Young's modulus of the conductive layer within the above range, the Young's modulus of the flexible thin speaker tends to be appropriately adjusted, and even if the conductive layer falls off the speaker body and comes into contact with an occupant, the trauma tends to be low.

The material used for the dielectric layer is not particularly limited as long as it can ensure flexibility and insulation between the pair of conductive layers, but it is preferable that it is a flexible polymer material. Flexible polymer materials include elastomers, thermoplastic resins, thermosetting resins, and rubber, such as natural rubber, urethane rubber, acrylic rubber, silicone rubber, butadiene rubber, nitrile rubber, hydrogenated nitrile rubber, and other nitrile group-containing rubbers, isoprene rubber, vulcanized rubber, styrene-butadiene rubber, butyl rubber, chlorosulfonated polyethylene rubber, ethylene propylene rubber, and fluorine-based polymers. It is preferable that the dielectric film is one that is prone to dielectric polarization when sandwiched between conductive layers with positive and negative charges.

The Young's modulus of the dielectric layer of the flexible thin speaker included in the automotive interior material of this embodiment is 5 GPa or less, preferably 1 GPa or less, more preferably 0.1 GPa or less, and particularly preferably 0.01 GPa or less. The lower limit of the Young's modulus of the dielectric layer of the flexible thin speaker is not particularly limited, but can be greater than 0 MPa and can be 0.01 MPa or more. By having the Young's modulus of the dielectric layer within the above range, the Young's modulus of the flexible thin speaker tends to be appropriately adjusted, and there is also a tendency for the dielectric layer to be less traumatic even if it falls off the speaker body and comes into contact with an occupant.

In the process of producing the flexible thin speaker included in the automotive interior material of this embodiment, the structure in which a dielectric layer is sandwiched between a pair of opposing conductive layers can be achieved by preparing the conductive layer and the dielectric layer separately and bonding them together during assembly, or by bonding them together during the manufacturing process, or by forming a metal layer on the surface of the dielectric layer by sputtering. One method of bonding them together during the manufacturing process is, for example, to supply the conductive layer and the dielectric layer from a roll and pass them through a nip roll that bonds them together with an adhesive applied to at least one of them. By bonding them together during the manufacturing process, it is possible to significantly shorten the cutting and bonding processes, and it is also easier to handle more complex shapes.

At least one of the pair of conductive layers of the flexible thin speaker included in the automobile interior material of this embodiment can include an insulating flexible substrate facing the dielectric layer. The flexible substrate may have air permeability, stretchability, and/or flexibility.
The term "insulating" as used herein means that the conductive layer has enough insulating properties to insulate an electric signal applied to the conductive layer, and refers to, for example, a volume resistivity of 1.0× ¹⁰ Ω·m or more. The volume resistivity is measured in accordance with JIS-K-6911. When the volume resistivity is in this range, it is possible to prevent an electric signal applied to the conductive layer from leaking from the surface and causing an electric shock.
The term "breathability" as used herein refers to a property that does not inhibit the sound pressure generated by the vibration of the conductive layer from escaping to the outside, and refers to an air permeability of 1 cc/ ^cm2 /sec or more, preferably 3 cc/ ^cm2 /sec or more, and more preferably 5 cc/ ^cm2 /sec. The air permeability in the thickness direction is measured using a Frazier type testing machine in accordance with JIS-L-1096, 1018 air permeability test method (method A air volume).
The term "elasticity" as used herein refers to, for example, a constant load elongation rate of 15% or more, preferably 20% or more, and more preferably 25% or more. The constant load elongation rate is measured in accordance with JIS-L-1096, Method B (constant load method for woven fabrics). Having the elasticity within this range makes it easier to install the sheet in a car.
In addition, the term "flexibility" as used herein refers to, for example, a Young's modulus of 5 GPa or less, preferably 1 GPa or less, more preferably 0.1 GPa or less, and particularly preferably 0.01 GPa or less. The lower limit of the Young's modulus is not particularly limited, but can be more than 0 MPa and can be 0.01 MPa or more. By having the Young's modulus of the flexible substrate within the above range, the Young's modulus of the flexible thin speaker tends to be appropriately adjusted, and even if the flexible substrate falls off the speaker body and comes into contact with an occupant, the trauma tends to be low.

The "flexible substrate" referred to here is not particularly limited as long as it has breathability while ensuring insulation, and can be selected from the group consisting of knitted fabrics, woven fabrics, leather, artificial leather, synthetic leather, nonwoven fabrics, resin sheets, rubber sheets, films, moisture-permeable waterproof sheets, three-dimensional resin models, and three-dimensional knitted fabrics, for example.
In addition, the "flexible substrate" does not have to be a single sheet, and may be a laminate of multiple sheets. For example, when the device is installed in a place where it is expected to be compressed by a passenger sitting or touching it, a layer that plays the role of a cushion may be inserted as a measure to prevent the vibration of the vibration part from being hindered even when a compressive force is applied. The material that can be used for the inserted layer is not particularly limited as long as it can ensure breathability and cushioning properties, and examples of the material include a urethane foam layer, a resin three-dimensional model, and a three-dimensional knitted fabric. From the viewpoint of ensuring breathability during compression, a three-dimensional knitted fabric can be preferably used.

From the viewpoint of preventing electric shock, at least one of the flexible substrates of the flexible thin speaker included in the automobile interior material may have a conductive layer facing the conductive layer, and this conductive layer may be connected to the earth. In this case, the conductive layer connected to the earth has an insulating skin layer facing the flexible substrate. This skin layer is not particularly limited as long as it has breathability and can ensure insulation, but can be selected from the group consisting of knitted fabric, woven fabric, leather, artificial leather, synthetic leather, nonwoven fabric, resin sheet, film, three-dimensional resin model, and three-dimensional knitted fabric. In this way, even if a current leaks beyond the flexible substrate, the current escapes through the conductive layer connected to the earth, preventing the current from flowing to the human body.

In the process of producing the flexible thin speaker included in the automotive interior material of this embodiment, the structure in which at least one of a pair of conductive layers has a flexible substrate facing a dielectric layer may be achieved by preparing the conductive layer, dielectric layer, and flexible substrate separately and bonding them together during assembly, or by bonding them together during the manufacturing process. One method of bonding them together during the manufacturing process is, for example, to supply the conductive layer, dielectric layer, and flexible substrate from a roll, and pass them through a nip roll that bonds them together with an adhesive applied to at least one of the adhesive surfaces of each layer. By bonding them together during the manufacturing process, it is possible to significantly shorten the cutting and bonding processes, and it is also easier to handle more complex shapes.

The flexible thin speaker included in the automotive interior material of this embodiment may be characterized in that the frequency characteristics do not change substantially when it is deformed. According to this invention, the electrodes are responsible for generating sound pressure or converting it into an electrical signal, so there is no change in frequency characteristics due to deformation, and the operation is stable even when it is deformed in three dimensions.

The flexible thin speaker included in the automobile interior material of this embodiment has a basis weight of 3000 g/m ² or less, preferably 2800 g/m ² or less, and more preferably 2500 g/m ² or less. By having the basis weight in this range, even when the speaker is arranged over a wide area inside the automobile, the increase in weight is small, which leads to preventing an increase in the weight of the vehicle body. Although a lighter weight is preferable as the lower limit of the basis weight, from the viewpoint of workability when lining the automobile interior, 50 g/m ² or more is more preferable. In addition, by having the basis weight of the flexible thin speaker in the above range, even if the automobile crashes and the flexible thin speaker body or its fragments come into contact with the passenger, the trauma tends to be low. Furthermore, when an automobile interior material including a flexible thin speaker is attached with an adhesive or a pressure-sensitive adhesive as described below, the flexible thin speaker tends to be less likely to fall off even when an automobile crash or the like occurs.

　An automobile interior material including the flexible thin speaker of this embodiment can be attached to at least one of the seats, headliner, headrest, console, armrest, door trim, carpet, and pillar parts inside the automobile using an adhesive or pressure sensitive adhesive. Because the thin speaker of this embodiment is flexible, it can be easily attached and installed in the automobile.

The flexible thin speaker included in the automobile interior material of this embodiment generates a noise cancellation signal that is in phase opposite to the environmental noise, thereby enhancing the noise reduction effect inside the automobile. In particular, by placing the automobile interior material including the flexible thin speaker of this embodiment in at least one of the headrest, seat, seat back, and pillar parts close to the passenger's ears, the effective canceling range can be significantly expanded.

The automobile interior material of this embodiment may be characterized in that it is arranged in at least one of the headrest, the seat surface, and the seat back of each passenger's seat, and is connected to an audio output device by a different wiring, thereby providing different sounds to each passenger. In this case, it is preferable to have a sound output surface and a non-sound output surface, and to install the surface farthest from the ears of the person closest to the speaker as the non-sound output surface. Furthermore, it is preferable to provide the non-sound output surface with sound insulation processing of 3 dB or more, more preferably 5 dB or more, and even more preferably 7 dB or more for 1000 Hz to 2000 Hz. The sound insulation processing referred to here is not particularly limited as long as it realizes sound insulation, but methods such as arranging a base material with sound insulation or sound absorption properties, canceling the output sound by applying sound waves in the opposite phase to the output sound, and reducing breathability by applying an adhesive or the like to the entire surface can be applied. By the sound insulation effect of the non-sound output surface being within this range, other passengers are unlikely to hear the sound, and only one passenger can hear the desired sound.

The flexible thin speaker included in the automobile interior material of this embodiment may be characterized in that the directivity ratio of the sound is 1.1 or more, preferably 1.2 or more, and more preferably 1.25 or more. With the directivity ratio of the sound in this range, the sound is difficult for other passengers to hear, and only the desired sound can be heard by one passenger. The "directivity ratio" of the sound referred to here is a value calculated by the following formula from the sound pressure when a pure sound of 1000 Hz is generated from a speaker installed in a specified direction and the sound is picked up by a microphone on an arc with a radius of 1 m from the speaker.
Sound directivity ratio = P0 _° ÷ _P90° (P0 _° : sound pressure (dB) measured in front of the speaker, _P90° : sound pressure (dB) measured at a position 90° from the front of the speaker)

The automobile interior material of this embodiment can be placed in locations inside the automobile where placement was previously difficult, making it possible to create a space that enhances the sense of realism of sound by installing multiple speakers. For example, when installed in two locations, the speakers can be placed on the left and right sides in front of the main passenger who will experience the sound, and positioned forward, ±20° to 35°, preferably ±22° to 33°, and more preferably 25° to 30°, based on a line connecting the main passenger and the front. By installing automobile interior material including flexible thin speakers within this range, a sound space can be experienced with a high sense of realism.

When the automobile interior material of this embodiment is installed in three locations, it may be characterized in that it is installed in front of the main passenger who will experience the sound, as well as on the left and right sides of the front, and the left and right speakers are positioned at ±20° to 35°, preferably ±22° to 33°, and more preferably 25° to 30° to the left and right of the front based on a line connecting the main passenger and the front speaker. By installing the automobile interior material within this range, a sound space can be experienced with a high sense of realism.

When the automobile interior material of this embodiment is installed in five locations, it may be characterized in that it is installed in front of the main occupant who will experience the sound, on the left and right sides of the front, and in two locations at the rear, with the left and right front speakers positioned ±20° to 35°, preferably ±22° to 33°, and more preferably 25° to 30° to the left and right of the front based on a line connecting the main occupant and the front speaker, and the two rear speakers positioned ±100° to 130°, preferably ±102° to 125°, and more preferably 105° to 120° rearward based on a line connecting the main occupant and the front speaker. By installing the automobile interior material within this range, a sound space can be experienced with a high sense of realism.

When the automobile interior material of this embodiment is installed in six locations, it may be characterized in that it is installed in front of the main passenger who will experience the sound, on the left and right sides of the front, and in three locations behind, with the left and right front speakers positioned ±20° to 35°, preferably ±22° to 33°, and more preferably 25° to 30° to the left and right of the front based on a line connecting the main passenger and the front speaker, the two rear speakers positioned ±90° to 130°, preferably ±92° to 125°, and more preferably 95° to 120° behind the line connecting the main passenger and the front speaker, and the single rear speaker positioned 180° behind the line connecting the main passenger and the front speaker. By installing the automobile interior material within this range, a sound space can be experienced with a high sense of realism.

When the automobile interior material of this embodiment is installed in seven locations, it may be characterized in that it is installed in four locations: in front of the main passenger who will experience the sound, on the left and right sides of the front, and behind, with the left and right speakers at ±20° to 35°, preferably ±22° to 33°, and more preferably 25° to 30°, to the left and right of the front based on a line connecting the main passenger and the front speaker, the two rear speakers at ±90° to 120°, preferably ±92° to 115°, and more preferably 95° to 110°, to the rear based on a line connecting the main passenger and the front speaker, and the two rear speakers at ±130° to 150°, preferably ±132° to 147°, and more preferably 135° to 145°, to the rear based on a line connecting the main passenger and the front speaker. By installing the automobile interior material within this range, a sound space can be experienced with a high sense of realism.

When the automotive interior material of this embodiment is installed in multiple locations, it may be characterized in that it is arranged so that it occupies 50% or more, preferably 55% or more, and more preferably 60% or more of the area of at least one of the headrest, seat cushion, seat back, pillar, headliner, instrument panel, and door trim. By installing the automotive interior material within this range, a highly realistic sound space can be experienced.

Furthermore, the automobile interior material of this embodiment may be arranged so as to occupy an area of at least one of the seat cushion, seat back, headliner, instrument panel, and door trim of at least 10%, preferably 12% or more, and more preferably 15% or more of the area of each. By placing the automobile interior material including the flexible speaker of this embodiment within this range, a highly realistic sound space can be experienced.

The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these.
The physical properties in the following examples were measured by the following methods. In principle, the various physical properties of the present invention are measured by the following methods, but if there are circumstances that make it impossible to measure them by the following methods, they can be measured by an appropriate and reasonable alternative method.

(1) Thickness (mm)
This was in accordance with JIS L 1913 Method B. The thickness was measured at three or more points under a load of 0.02 kPa, and the average value was calculated.

(2) Bending resistance (mm)
The bending resistance of the flexible speaker for automobile interiors is measured using a 45° cantilever type testing machine in accordance with JIS-L-1096:2010, Method A (45° cantilever method).

(3) Air permeability (cc/ ^cm2 /sec)
According to JIS-L-1096, 1018 air permeability test method (method A air amount), the air permeability through the flexible substrate is measured using an air permeability tester FX3300 Laboair IV manufactured by Takayama Reed Co., Ltd.

(4) Elasticity (%)
The stretchability of the flexible substrate is measured according to JIS-L-1096, Method B (constant load method for woven fabrics).

(5) Insulation (Ω・m)
The volume resistivity of the flexible substrate is measured by the double ring method in accordance with JIS-K-6911.

(6) Weight (g/ ^m2 )
The basis weight of the flexible thin speaker for automobile interior use is measured in accordance with JIS L 1913.

(7) Young's modulus (GPa)
A tensile test is carried out and the Young's modulus is measured in accordance with JIS-K-7127.

(8) Sound insulation performance (dB)
In accordance with JIS-A-1441, a sample is attached to the opening at the connection between the reverberation chamber and the anechoic chamber, and an acoustic intensity probe is used to measure the sound transmission loss from the sound output surface direction to the non-sound output surface direction of a flexible speaker for automobile interiors.

(9) Sound directivity ratio (-)
This value is calculated using the following formula from the sound pressure when a 1000 Hz pure tone is generated from a speaker installed in a specified direction in a 4m x 4m space with a background noise level of 40dB or less, and the sound is picked up by a microphone on an arc with a radius of 1m from the speaker.
Sound directivity ratio = P0 _° ÷ _P90° (P0 _° : sound pressure (dB) measured in front of the speaker, _P90° : sound pressure (dB) measured at a position 90° from the front of the speaker)

(10) Installation inside a car Whether or not the tape could be installed inside a car while applying stress was judged as OK or not.

(11) Sound frequency characteristics Pure tones of 500 Hz, 1000 Hz, and 2000 Hz are generated from a speaker placed in a 4 m x 4 m space with a background noise level of 40 dB or less, so that the speaker is not deformed. The ratio of the sound pressure measured by a microphone at a distance of 1 m from the speaker to the sound pressure measured by the same procedure when the speaker is placed in a parked car with a background noise level of 40 dB or less is considered to have passed the test.

(12) Appearance Eight panelists were asked to perform a sensory evaluation on whether they felt a sense of unity between the speakers and the interior of the vehicle, using the following three-level evaluation criteria, and the most frequent value was used as the evaluation result.
3: I feel a sense of unity 2: I can't say either way 1: I don't feel a sense of unity

(13) Noise reduction effect When the environmental noise was measured while the car was running, and at the same time, a noise canceling signal in the opposite phase to the environmental noise was output, the monitor in the car was asked to perform a sensory evaluation according to the following 5-point evaluation standard to see if it felt that the noise was reduced, and the most frequent value was used as the evaluation result. The number of monitors was 8.
5: Noise reduction effect is felt considerably 4: Noise reduction effect is felt 3: Noise reduction effect is felt to some extent 2: No noise reduction effect is felt almost at all 1: No noise reduction effect is felt at all

(14) Sound space design for each passenger The passenger who was to experience the sound was seated in the passenger seat, and the monitor was seated in the rear seat directly behind him. The passenger who was to experience the sound was made to listen to a 1000 Hz pure tone at a sound pressure of 60 dB at the ears. The monitor was asked to perform a sensory evaluation using the following 5-point evaluation standard to see if he or she felt sound leakage, and the most frequent value was used as the evaluation result. The number of monitors was 8.
5: No sound leakage at all 4: Almost no sound leakage 3: Very little sound leakage 2: Some sound leakage 1: Sound leakage

(15) Realism The monitors who experienced the sound were seated in the center of the back seat, and when they heard a 1000 Hz pure tone with a sound pressure of 60 dB at their ears, they were asked to perform a sensory evaluation on the following 5-point evaluation standard to see if they felt sound leakage, and the most frequent value was used as the evaluation result. The number of monitors was 8.
5: Feels very real 4: Feels real 3: Feels a little real 2: Feels almost no real 1: Does not feel real at all

[Example 1]
A pair of conductive layers was formed using a 0.5 mm thick, 100 mm square knitted fabric made of conductive fibers with a core of nylon and a silver-plated surface, and a 0.3 mm thick, 120 mm square electret film (POREFLON (registered trademark) membrane, manufactured by Sumitomo Electric Fine Polymer Co., Ltd., product number HP-010-30) made of a fluorine-based polymer was sandwiched between the pair of conductive layers, and each layer was bonded by applying an acrylic adhesive in a mesh shape to obtain a conductive layer-dielectric layer-conductive layer structure. At this time, wiring was connected to each of the pair of conductive layers. Furthermore, an acrylic adhesive was applied in a mesh shape to the outer layer of the conductive layer so that the sound pressure generated in the conductive layer could pass through. Furthermore, a 150 mm square tricot knitted fabric made of polyester was attached to this as a flexible substrate to obtain an automobile interior material including a flexible speaker. When a 150 mm square piece of the headliner skin of a car was cut out and replaced with an automobile interior material containing a flexible thin speaker, and an electrical signal was given to output a 1000 Hz pure tone through wiring, sound could be output without any problems. In addition, the thickness did not protrude from the conventional headliner, and the appearance of the interior of the car was maintained. The results are shown in Table 1 below.

[Example 2]
An automobile interior material including a flexible speaker was obtained in the same manner as in Example 1, except that the flexible substrate was changed to artificial leather (Dinamica (registered trademark), manufactured by Asahi Kasei Corporation, basis weight: 290 g/ ^m2 ) and the dielectric layer was changed to a 0.25 mm thick sheet made of natural rubber. A car headrest skin was cut into a 150 mm square and an automobile interior material including a flexible thin speaker was attached instead. An electrical signal was applied via wiring to output a pure tone of 1000 Hz, and sound was output without any problems. Furthermore, the thickness did not protrude from the conventional headrest, and the appearance of the interior of the car was maintained. The results are shown in Table 1 below.

[Example 3]
Except for changing the flexible substrate to a three-dimensional knitted fabric, an automobile interior material including a flexible speaker was obtained in the same manner as in Example 1. Using a double raschel knitting machine equipped with six reeds and having a gauge of 22 and a hook interval of 6 mm, two false twisted yarns of 167 decitex 48 filament polyethylene terephthalate fiber were aligned and supplied in a 1-out-1-in (L2) and 1-in-1-out (L3) arrangement from two reeds (L2, L3) forming the knitted fabric of the front layer, a monofilament of 110 decitex polyethylene terephthalate fiber was supplied in a 1-out-1-in arrangement from one reed (L4) forming the connecting portion, and further, false twisted yarns of 167 decitex 48 filament polyethylene terephthalate fiber were supplied in an all-in arrangement from two reeds (L5, L6) forming the knitted fabric of the back layer.
A three-dimensional knitted fabric was knitted at a density of 35 courses/2.54 cm with the knit structure shown below. The resulting grey fabric was stretched by 1% and dry-heat set at 175° C. for 1 minute with an overfeed rate of 0%, to obtain a three-dimensional knitted fabric.
(Editing organization)
L1: -
L2:1011/2322/
L3:2322/1011/
L4:3410/4367/
L5:0001/1110/
L6:2234/2210/
When the seat back skin of a car was cut into 150 mm square pieces, and instead an automobile interior material including a flexible speaker was attached, and an electrical signal was given to output a 1000 Hz pure tone through wiring, sound could be output without any problems. In addition, the thickness did not protrude from the conventional seat back, and the appearance of the interior of the car was maintained. The results are shown in Table 1 below.

[Example 4]
A thin silver film was formed on both sides of the dielectric layer by a two-pole sputtering method, and a 120 mm square conductive layer-dielectric layer-conductive layer structure was obtained, but an automobile interior material including a flexible speaker was obtained in the same manner as in Example 1. A headrest skin of an automobile was cut into a 150 mm square, and an automobile interior material including a flexible thin speaker was attached instead. When an electrical signal was applied to output a pure tone of 1000 Hz through wiring, sound could be output without any problems. In addition, the thickness did not protrude from the conventional headrest, and the appearance of the interior of the vehicle was maintained. The results are shown in Table 1 below.

[Example 5]
Using the same conductive layer, dielectric layer, and flexible substrate as those used in Example 1, an acrylic adhesive was applied in stripes on both sides of an electret film supplied from a roll, and a silver conductive fiber knit was separately supplied from a roll from both the top and bottom sides, and wound through a nip roll to obtain a conductive layer-dielectric layer-conductive layer structure. The structure was further supplied from a roll, and an acrylic adhesive was applied in stripes on both sides, and a polyester tricot knit was supplied from both the top and bottom sides, and wound through a nip roll to obtain an automobile interior material including a flexible speaker. This automobile interior material was cut into 150 mm squares, and wiring was connected to each of the pair of conductive layers. When an automobile headrest skin was cut into 150 mm squares, and an automobile interior material including a flexible thin speaker was attached instead, and an electrical signal was applied to output a pure tone of 1000 Hz through wiring, sound could be output without any problems. In addition, the thickness did not protrude from the conventional headrest, and the interior view of the vehicle was maintained. The results are shown in Table 1 below.

[Example 6]
The automobile interior material including the flexible speaker obtained in Example 1 was installed on the headrest skin, and when the automobile was traveling on a flat road at a speed of 70 km/h, a waveform in opposite phase to the noise picked up by an environmental noise pickup microphone installed nearby was output from the flexible speaker. The results are shown in Table 1 below.

[Example 7]
Except for changing one of the flexible substrates arranged so as to sandwich the pair of conductive layers to a sound-insulating sheet made of a polyolefin-based material, an automobile interior material including a flexible thin speaker was obtained in the same manner as in Example 1. This automobile interior material was placed on the headrest skin so that the sound-insulating sheet surface was the side farthest from the passenger's ears, and the results when a pure tone of 1000 Hz was generated are shown in Table 1 below.

[Example 8]
Except for the fact that one of the flexible substrates arranged so as to sandwich the pair of conductive layers was entirely coated with an acrylic adhesive, an automobile interior material including a flexible speaker was obtained in the same manner as in Example 1. This automobile interior material including a flexible thin speaker was placed on the headrest skin so that the entirely acrylic adhesive-coated surface was the side farthest from the ears of the passenger in the vehicle, and the results when a pure tone of 1000 Hz was generated are shown in Table 1 below.

[Example 9]
An automobile interior material including the flexible speaker obtained in Example 1 was positioned on the backs of the driver's seat and passenger seat so that the angle when viewed from the rear center seat was ±30°, and a pure tone of 1000 Hz was generated. The sense of realism felt by the passenger sitting in the rear center seat was evaluated and the results are shown in Table 1 below.

[Example 10]
Automotive interior materials containing the flexible thin speaker obtained in Example 1 were placed in three locations: the center console and the backs of the driver's seat and passenger seat, so that the angles when viewed from the rear center seat were 0° for the center console and ±30° for the driver's seat and passenger seat, respectively. A pure tone of 1000 Hz was generated, and the sense of realism felt by the passenger sitting in the rear center seat was evaluated. The results are shown in Table 2 below.

[Example 11]
Automotive interior materials containing the flexible thin speaker obtained in Example 1 were arranged in a total of five locations, namely the center console, the backs of the driver's seat and passenger seat, and two C-pillars, so that the angles as seen from the rear center seat were 0° for the center console, ±30° for the driver's seat and passenger seat, and ±110° for the two C-pillars. A pure tone of 1000 Hz was generated, and the sense of realism felt by the passenger sitting in the rear center seat was evaluated. The results are shown in Table 2 below.

[Example 12]
Automotive interior materials containing the flexible thin speaker obtained in Example 1 were arranged in a total of six locations, namely the center console, the backs of the driver's and passenger's seats, two locations on the C-pillars, and the rear gate, so that the angles as seen from the rear center seat were 0° for the center console, ±30° for the driver's seat and passenger's seat, ±100° for the two locations on the C-pillars, and 180° for the rear gate. A pure tone of 1000 Hz was generated, and the sense of realism felt by the passenger sitting in the rear center seat was evaluated. The results are shown in Table 2 below.

[Example 13]
Automotive interior materials containing the flexible thin speaker obtained in Example 1 were positioned in a total of seven locations, including the center console, the backs of the driver's and passenger's seats, two C-pillars, and two D-pillars, so that the angles as seen from the rear center seat were 0° for the center console, ±30° for the driver's seat and passenger's seat, ±100° for the two C-pillars, and ±140° for the two D-pillars. A pure tone of 1000 Hz was generated, and the sense of realism felt by the passenger sitting in the rear center seat was evaluated. The results are shown in Table 2 below.

[Example 14]
An automobile interior material including the flexible thin speaker obtained in Example 1 was installed so as to cover 50% of the area of the headliner, and a pure tone of 1000 Hz was generated. The sense of realism felt by a passenger sitting in the rear center seat was evaluated, and the results are shown in Table 2 below.

[Comparative Example 1]
An automobile interior material including a flexible speaker was obtained in the same manner as in Example 1, except that the flexible substrate was changed to a tricot knit with polyurethane foam. The headrest skin of an automobile was cut into 150 mm squares, and instead, an automobile interior material including a flexible speaker was attached. When an electric signal was applied to output a pure tone of 1000 Hz through wiring, the thickness was large and the sense of unity with the interior was lost. In addition, due to low flexibility and stretchability, it could not be stretched when stretched inside the automobile, and the followability could not be guaranteed. Furthermore, due to low breathability of the flexible substrate, the frequency characteristics of the high frequency range sound were impaired. The results are shown in Table 2 below.

[Example 15]
The automobile interior material including the flexible thin speaker obtained in Example 1 was installed in the air conditioner outlet of the instrument panel, and when the automobile was driven on a flat road at a speed of 70 km/h, a waveform in opposite phase to the noise picked up by an environmental noise pickup microphone installed nearby was output from the flexible speaker. The results are shown in Table 2 below.

[Example 16]
Except for changing one of the flexible substrates arranged so as to sandwich the pair of conductive layers to a highly breathable polyester knit, an automobile interior material including a flexible thin speaker was obtained in the same manner as in Example 1. This automobile interior material was placed on the headrest skin so that the highly breathable polyester knit surface was the side farthest from the passenger's ears, and the results when a pure tone of 1000 Hz was generated are shown in Table 2 below.

[Comparative Example 2]
A pure tone of 1000 Hz was generated from an existing car speaker. The speaker positions, as seen from the rear center seat, were ±40° at the front door trim position and ±80° at the rear door trim position. The evaluation result of the sense of realism felt by the passenger sitting in the rear center seat was "1".

[Example 17]
An automobile interior material including the flexible thin speaker obtained in Example 1 was installed so as to cover 40% of the area of the headliner, and a pure tone of 1000 Hz was generated. The sense of realism felt by a passenger sitting in the rear center seat was evaluated, and the results are shown in Table 2 below.

　The automotive interior material including the flexible thin speaker of the present invention is sufficiently thin and flexible, making it suitable for use in parts of the interior of an automobile, such as seats, headliners, headrests, consoles, armrests, door trim, and carpets.

Reference Signs List 1 Automotive interior material including flexible thin speaker 2 Dielectric layer 3 Pair of conductive layers 3' Pair of conductive layers 4 Flexible insulating base material 4' having breathability or stretchability Flexible insulating base material t Thickness of automotive interior material including flexible thin speaker 5 Sound insulation processing 6 Flexible diaphragm

Claims (22)

An automotive interior material including a flexible thin speaker that is 30 mm thick or less and generates sound pressure by vibrating a flexible diaphragm. An automobile interior material including the flexible thin speaker according to claim 1, in which a dielectric layer is disposed between a pair of opposing conductive layers, and when an electrical signal is applied to the pair of conductive layers, the pair of conductive layers and the dielectric layer vibrate together to generate sound pressure. The automotive interior material including the flexible thin speaker according to claim 2, wherein at least one of the pair of conductive layers further comprises an insulating flexible substrate having breathability or elasticity facing the dielectric layer. An automobile interior material including a flexible thin speaker according to claim 2 or 3, wherein at least one of the pair of conductive layers is made of conductive fibers. An automobile interior material including the flexible thin speaker according to claim 1 or 2, the frequency characteristics of which do not substantially change when deformed. 3. An automobile interior material comprising the flexible thin speaker according to claim 1 or 2, wherein the flexible thin speaker has a basis weight of 3000 g/ ^m2 or less. An automobile interior material including the flexible thin speaker according to claim 1 or 2, wherein the bending resistance of the flexible thin speaker is 300 mm or less. An automobile interior material including the flexible thin speaker according to claim 1 or 2, wherein the Young's modulus of the flexible thin speaker is 10 GPa or less. An automobile having an automobile interior material including a flexible thin speaker, in which the automobile interior material including the flexible thin speaker according to claim 1 or 2 is attached by an adhesive or pressure sensitive adhesive to at least one of the seats, headliner, headrest, console, armrest, door trim, carpet, and pillar parts inside the automobile. An automobile having an automobile interior material including the flexible thin speaker according to claim 1 or 2, which is arranged in at least one of the headrest, seat, seat back, and pillar parts inside the automobile and generates a noise cancellation signal in anti-phase with environmental noise. An automobile having an automobile interior material including the flexible thin speaker according to claim 1 or 2, which is arranged in at least one of the headrest, seat surface, and seat back of each passenger's seat and is connected to an audio output device by a separate wiring, thereby providing different sounds to each passenger. A thin automotive speaker having an automotive interior material including the flexible thin speaker according to claim 1 or 2, which has a sound output surface and a non-sound output surface, and the non-sound output surface is provided with a sound insulation treatment of 3 dB or more for frequencies from 1000 Hz to 2000 Hz. An automobile having an automobile interior material including the flexible thin speaker according to claim 1 or 2, the surface farthest from the nearest person's ears being a non-sound output surface when the speaker is installed as an automobile interior. An automobile having an automobile interior material including the flexible thin speaker according to claim 1 or 2, the sound directivity ratio of which is 1.1 or more. An automobile having an automobile interior material including the flexible thin speaker according to claim 1 or 2, which is either a front or front left/right speaker positioned at 0° or ±20° to 35° with respect to a line connecting the main occupant experiencing the sound and the front. An automobile having an automobile interior material including the flexible thin speaker according to claim 1 or 2, which is a front speaker positioned at 0° with respect to a line connecting the main occupant who experiences the sound and the front, and front left and right speakers positioned at ±20° to 35° to the left and right with respect to the line connecting the front. An automobile having an automobile interior material including the flexible thin speaker according to claim 1 or 2, which is a front speaker arranged at 0° with respect to a line connecting the main occupant who experiences the sound and the front, front left and right speakers arranged at ±20° to 35° to the left and right of the front with respect to the line connecting the front, and two rear speakers arranged at ±100° to 130° rearward with respect to the line connecting the front. An automobile having an automobile interior material including the flexible thin speaker according to claim 1 or 2, which is a front speaker arranged at 0° with respect to a line connecting the main occupant experiencing the sound and the front as a reference, front left and right speakers arranged at ±20° to 35° to the left and right of the front with respect to the line connecting the front, two rear speakers arranged at ±90° to 130° rearward with respect to the line connecting the front, and one rear speaker arranged 180° rearward with respect to the line connecting the front. An automobile having an automobile interior material including the flexible thin speaker according to claim 1 or 2, which is a front speaker arranged at 0° with respect to a line connecting the main occupant experiencing the sound and the front, front left and right speakers arranged at ±20° to 35° to the left and right of the front with respect to the line connecting the front, two rear speakers arranged at ±90° to 120° rearward with respect to the line connecting the front, and two rear speakers arranged at ±130° to 150° rearward with respect to the line connecting the front. An automobile having an automobile interior material including the flexible thin speaker according to claim 1 or 2, which is arranged in at least one of the following areas: the front of the headrest, the side of the headrest, the back of the headrest, the pillar, the console, and the armrest, so as to occupy 50% or more of the area of each of the following areas: An automobile having an automobile interior material including the flexible thin speaker according to claim 1 or 2, which is arranged in at least one of the seat cushion, seat back, headliner, instrument panel, and door trim so as to occupy an area of 10% or more of the area of each of the following: An automobile having an automobile interior material including the flexible thin speaker according to claim 1 or 2.

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