JP2019003011A - Laminate, laminated glass, windshield glass, and video display system - Google Patents

Abstract

To provide a laminate that, when sandwiching a function layer reflecting part of visible light and transmitting part of the visible light with transparent substrates, improves display quality of a video display system, while maintaining the performance required for the transparent substrates, a laminated glass, a windshield glass, and the video display system.SOLUTION: A laminate comprises: a first transparent substrate; a function layer transmitting part of visible light and reflecting part of the visible light; and a second transparent substrate. When the transmittance toward the first transparent substrate from the function layer is T1, and the transmittance toward the second transparent substrate from the function layer is T2, the following formula (1) is satisfied, and the transmittance exceeds 70%. (1) T1>T2.SELECTED DRAWING: None

Description

  The present invention relates to a laminate, laminated glass, windshield glass, and an image display system.

  There is an increasing demand for systems that project images onto a transparent screen, including head-up display systems for in-vehicle use. As one of the means for realizing the above, an image display system using a so-called half mirror that transmits part of visible light and reflects part of the visible light is studied. For example, a cholesteric liquid crystal layer is used as one of the half mirrors. (Patent Document 1).

International Publication No. 2016/052367

  On the other hand, for example, when a half mirror is sandwiched between laminated glasses, for example, in-vehicle applications, the display quality of the video display system may be lowered due to properties such as heat shielding and color originally required for laminated glass. all right.

  Therefore, in the present invention, when a functional layer that reflects part of visible light and transmits part of it is sandwiched between transparent substrates, the display quality of the video display system is improved while maintaining the properties required for the transparent substrate. It is an object of the present invention to provide a laminated body, a laminated glass, a windshield glass, and an image display system using the laminated body.

  As a result of intensive studies by the inventors, in the laminate having the first transparent substrate, the functional layer that transmits part of visible light and reflects part thereof, and the second transparent substrate, the first layer is more functional than the functional layer. When T1 is the transmittance on the transparent substrate side and T2 is the transmittance on the second transparent substrate side of the functional layer, T1 and T2 have a specific relationship, and the transmittance of the entire laminate is a specific value. Thus, it has been found that it is possible to provide a laminate that improves the display quality of a video display system while maintaining the properties required for a transparent substrate, and a laminated glass, windshield glass, and video display system using the same. .

  That is, it has been found that the above-described problem can be achieved by the following configuration.

[1] A first transparent substrate, a functional layer that transmits a part of visible light and reflects a part thereof, and a second transparent substrate. The transmittance on the first transparent substrate side from the functional layer is T1. A laminate that satisfies the following formula (1) and has a transmittance of more than 70% when the transmittance on the second transparent substrate side from the functional layer is T2.
T1> T2 (1)
Here, the transmittance refers to a value measured according to the visible light transmittance test described in JIS R3212 (2015), procedure 1).
[2] The laminate according to [1], which has adhesive layers between the first transparent substrate and the functional layer and between the second transparent substrate and the functional layer.
[3] The laminate according to [2], wherein each of the adhesive layers contains polyvinyl butyral and an ethylene-vinyl acetate copolymer.
[4] The functional layer includes any one of [1] to [3] including any one of a cholesteric liquid crystal layer, a dielectric multilayer film layer, a reflective layer having a Fresnel lens, and a reflective layer having a half mirror shape. The laminated body of description.
[5] The laminate according to any one of [1] to [4], further satisfying the following formula (2).
T1-T2> 3% (2)
[6] The laminate according to any one of [1] to [5], wherein at least one of the first transparent substrate and the second transparent substrate is a glass substrate.
[7] The laminate according to [6], wherein both the first transparent substrate and the second transparent substrate are glass substrates.
[8] The laminate according to [7], wherein the first transparent substrate is colorless glass and the second transparent substrate is colored glass.
[9] A laminated glass having the laminate according to any one of [1] to [8].
[10] A windshield glass having the laminate according to any one of [1] to [8] or the laminated glass according to [9], wherein the second transparent substrate is disposed on the outside light side.
[11] The laminate according to any one of [1] to [8], the laminated glass according to [9], or the windshield glass according to [10], and an image source that emits image light. And an image display system in which an image source is arranged on the first transparent substrate side.

  ADVANTAGE OF THE INVENTION According to this invention, the laminated body which improves the display quality of a video display system, the laminated glass using the same, a windshield glass, and a video display system can be provided, maintaining the property calculated | required by a transparent substrate. .

It is typical sectional drawing which shows the example of embodiment of the laminated body of this invention. It is a schematic diagram which shows the example of embodiment of the video display system of this invention.

Hereinafter, the present invention will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
Further, in this specification, parallel and orthogonal do not mean parallel or orthogonal in a strict sense, but mean a range of ± 5 ° from parallel or orthogonal.

  In the present specification, the liquid crystal composition and the liquid crystal compound include a concept that no longer exhibits liquid crystallinity due to curing or the like.

  In the present specification, when referring to the area and shape of a film-like or layer-like one, it means the area and shape of the main surface (front surface or back surface), respectively, unless otherwise specified.

In this specification, “selective” for circularly polarized light means that the amount of light of either the right circularly polarized component or the left circularly polarized component of light is greater than that of the other circularly polarized component. Specifically, when referred to as “selective”, the degree of circular polarization of light is preferably 0.3 or more, more preferably 0.6 or more, and even more preferably 0.8 or more. More preferably, it is substantially 1.0. Table In _{/ (I R + I L)} | Here, the degree of circular polarization, the intensity of the right circularly polarized light component of the light _{I R,} when the strength of the left-handed circularly polarized light component and _{I L,} | _I R -I _L Is the value to be

  In this specification, “sense” for circularly polarized light means right circularly polarized light or left circularly polarized light. The sense of circularly polarized light is right-handed circularly polarized light when the electric field vector tip turns clockwise as time increases when viewed as the light travels toward you, and left when it turns counterclockwise. Defined as being circularly polarized.

  In this specification, the term “sense” may be used for the twist direction of the spiral of the cholesteric liquid crystal. When the twist direction (sense) of the spiral of the cholesteric liquid crystal is right, it reflects right circularly polarized light and transmits left circularly polarized light. When the sense is left, it reflects left circularly polarized light and transmits right circularly polarized light.

In this specification, “light” means visible light and natural light (unpolarized light) unless otherwise specified. Visible light is light having a wavelength that can be seen by human eyes among electromagnetic waves, and usually indicates light having a wavelength range of 380 nm to 780 nm.
In this specification, the measurement of the light intensity required in connection with the calculation of the light transmittance may be performed by using, for example, a normal visible spectrum meter and measuring the reference as air.
In the present specification, the term “reflected light” or “transmitted light” is used to mean scattered light and diffracted light.

In addition, the polarization state of each wavelength of light can be measured using a spectral radiance meter or a spectrometer equipped with a circularly polarizing plate. In this case, the intensity of the light measured through the right circular polarizing plate I _R, the intensity of the light measured through the left circular polarizing plate corresponds to I _L. Moreover, even if a circularly polarizing plate is attached to an illuminometer or a spectrum meter, the measurement can be performed. The ratio can be measured by attaching a right circular polarized light transmission plate, measuring the right circular polarized light amount, attaching a left circular polarized light transmission plate, and measuring the left circular polarized light amount.

  In this specification, p-polarized light means polarized light that vibrates in a direction parallel to the light incident surface. The incident surface means a surface that is perpendicular to the reflecting surface (such as the laminated glass surface) and includes the incident light beam and the reflected light beam. In p-polarized light, the vibration plane of the electric field vector is parallel to the incident plane. In this specification, s-polarized light means polarized light that vibrates in a direction perpendicular to the light incident surface.

  In this specification, the front phase difference is a value measured using an AxoScan manufactured by Axometrics. The measurement wavelength is 550 nm unless otherwise specified. The front phase difference may be a value measured by making light having a wavelength in the visible light wavelength region incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments). When selecting the measurement wavelength, the wavelength selection filter can be exchanged manually, or the measurement value can be converted by a program or the like.

  In the present specification, the birefringence (Δn) of the liquid crystal compound is defined as p. It is a value measured according to the method described in 214. Specifically, Δn at 60 ° C. can be obtained by injecting a liquid crystal compound into a wedge-shaped cell, irradiating it with light having a wavelength of 550 nm, and measuring the refraction angle of transmitted light.

In this specification, “projection image” means an image based on the projection of light from a projector to be used, not a surrounding landscape such as the front. The projected image is observed as a real image observed on the surface of the laminated glass, or a virtual image that appears above the projected image display portion of the windshield glass as viewed from the observer.
In this specification, “screen image” means an image displayed on a drawing device of a projector or an image drawn on an intermediate image screen or the like by the drawing device.
Both the image and the projected image may be a single color image, a multicolor image of two or more colors, or a full color image.

<< Transmissivity >>
In this specification, the transmittance refers to a value measured using SR-3UL1 (Topcon Corporation) in accordance with the visible light transmittance test described in JIS R3212 (2015), procedure 1).

<Laminate>
FIG. 1 shows a schematic cross-sectional view of the laminate of the present invention. The laminate 10 of the present invention includes a first transparent substrate 1, a functional layer 4 that transmits part of visible light and reflects part thereof, and a second transparent substrate 6. When the transmittance on the transparent substrate 1 side is T1 and the transmittance on the second transparent substrate 6 side from the functional layer 4 is T2, the laminate satisfies the following formula (1) and the transmittance is more than 70%. is there.
T1> T2 (1)
Here, the transmittance refers to a value measured according to the visible light transmittance test described in JIS R3212 (2015), procedure 1).

  In addition, the first adhesive layer 2 may be provided between the first transparent substrate 1 and the functional layer 4, and the second adhesive layer 5 may be provided between the second transparent substrate 6 and the functional layer 4. Further, the retardation layer 3 may be provided on the functional layer 4.

  Moreover, the laminated body of this invention may have another layer in between, and the functional layer may consist of multiple layers.

With the above configuration, it is possible to improve the display performance (brightness of display image, color change, etc.) as a video display system while maintaining the heat shielding property as a function of the conventional laminated glass. Furthermore, it is possible to reduce the reflected light by the functional layer of external light and to reduce the appearance color change.
That is, by increasing the transmittance on the transparent substrate side on the image source side when used as an image display system and decreasing the transmittance on the opposite side, the display performance can be improved while maintaining the ability to absorb external light. .

Here, the transmittances T1 and T2 are the transmittances of all the regions outside the functional layer in the laminate.
That is, in order to obtain a desired configuration, the transmittance of the transparent substrate may be adjusted, the transmittance of an adhesive layer described later may be adjusted, or when a support is provided on the functional layer, the support is provided. The transmittance may be adjusted. Examples of a method for adjusting the transmittance include a method of mixing a known pigment.

Moreover, since the laminated body of this invention can improve the display quality of a video display system, maintaining the property calculated | required by a transparent substrate more effectively, it is still more preferable to satisfy | fill following formula (2).
T1-T2> 3% (2)

[Transparent substrate]
Various known transparent substrates can be used as the transparent substrate used in the present invention. Specifically, resin substrates, such as a glass substrate and a polycarbonate, are mentioned.
When the laminate of the present invention is used in a windshield glass or an image display system, the first transparent substrate is the indoor side or the image source side, and the second transparent substrate is the outside light side or the side opposite to the image source. preferable. For example, when a glass substrate is used, it is preferable to use colorless glass as the first transparent substrate and colored glass as the second transparent substrate.

  Although there is no restriction | limiting in particular about the thickness of a transparent substrate, What is necessary is just about 0.5 mm-5.0 mm, 1.0 mm-3.0 mm are preferable, and 1.6 mm-2.3 mm are more preferable. The thicknesses of the first transparent substrate and the second transparent substrate may be the same as or different from each other. For example, the second transparent substrate may be 1.9 mm to 2.5 mm, and the first transparent substrate may be 1.6 mm to 1.9 mm.

[Functional layer that transmits part of visible light and reflects part of it]
The functional layer that transmits part of visible light and reflects part of the visible light used in the present invention is not particularly limited as long as it is a functional layer that transmits part of visible light that is incident on the laminate and transmits part of the visible light. . Specific examples of the functional layer include a cholesteric liquid crystal layer, a dielectric multilayer film layer, a reflective layer having a Fresnel lens, and a reflective layer having a half mirror shape.

{Cholesteric liquid crystal layer}
Examples of the cholesteric liquid crystal layer used in the present invention include a solid coating layer of cholesteric liquid crystal and a layer containing a plurality of cholesteric liquid crystal dots.
One or more cholesteric liquid crystal layers used in the present invention may be included. Other layers such as an alignment layer and an adhesive layer may be included between the two or more cholesteric liquid crystal layers. Further, a retardation layer may be provided on the cholesteric liquid crystal layer, and other layers such as a base layer and a transparent layer may be included between the cholesteric liquid crystal layer and the retardation layer.

(Cholesteric liquid crystal structure)
The cholesteric liquid crystal structure may be any structure as long as the orientation of the liquid crystal compound in the cholesteric liquid crystal phase is maintained. Typically, the polymerizable liquid crystal compound is placed in the orientation state of the cholesteric liquid crystal phase and then irradiated with ultraviolet rays. Any structure may be used as long as it is polymerized and cured by heating or the like and has no fluidity, and at the same time, the structure does not change the orientation form due to an external field or an external force. In the cholesteric liquid crystal structure, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained, and the liquid crystal compound may no longer exhibit liquid crystallinity. For example, the polymerizable liquid crystal compound may have a high molecular weight due to a curing reaction and may no longer have liquid crystallinity.

It is known that the cholesteric liquid crystal phase exhibits circularly polarized light selective reflection that selectively reflects the circularly polarized light of either the right circularly polarized light or the left circularly polarized light and transmits the circularly polarized light of the other sense. In this specification, the circularly polarized light selective reflection is sometimes simply referred to as selective reflection.
As a film including a layer in which a cholesteric liquid crystal phase exhibiting circularly polarized light selective reflection is fixed, many films formed from a composition containing a polymerizable liquid crystal compound have been conventionally known. Regarding a cholesteric liquid crystal structure or a cholesteric liquid crystal layer, The prior art can be referred to.

  The central wavelength λ of selective reflection of the cholesteric liquid crystal structure depends on the pitch P (= helical period) of the helical structure in the cholesteric phase, and follows the relationship between the average refractive index n of the cholesteric liquid crystal structure and λ = n × P. In this specification, the central wavelength λ of selective reflection of the cholesteric liquid crystal structure is the reflection of the circularly polarized reflection spectrum measured from the normal direction of the cholesteric liquid crystal layer or the normal direction of the surface on which the cholesteric liquid crystal dots are formed. It means the wavelength at the center of gravity of the peak.

The selective reflection center wavelength and the half-value width of the cholesteric liquid crystal structure can be obtained as follows.
When a transmission spectrum of the cholesteric liquid crystal structure (measured from the normal direction of the cholesteric liquid crystal layer) is measured using a spectrophotometer UV3150 (Shimadzu Corporation), a decrease in transmittance peak is observed in the selective reflection band. Of the two wavelengths having an intermediate (average) transmittance between the minimum transmittance of this peak and the transmittance before the decrease, the wavelength value on the short wavelength side is λ _l (nm), and the wavelength value on the long wavelength side is Is λ _h (nm), the central wavelength λ and the half-value width Δλ of selective reflection can be expressed by the following equations.
λ = (λ ₁ + λ _h ) / 2
Δλ = (λ _h −λ _l )
The selective reflection center wavelength obtained as described above substantially coincides with the wavelength at the center of gravity of the reflection peak of the circularly polarized reflection spectrum measured from the normal direction.

  As can be seen from the above relationship of λ = n × P, the center wavelength of selective reflection can be adjusted by adjusting the pitch of the helical structure. The cholesteric liquid crystal layer exhibiting selective reflection in the visible light region preferably has a center wavelength of selective reflection in the visible light region. By adjusting the n value and the P value, for example, the center wavelength λ is adjusted to selectively reflect either the right circularly polarized light or the left circularly polarized light with respect to red light, green light, and blue light. be able to.

For example, when used in a head-up display system, the laminated body is designed so that light is incident obliquely with respect to the cholesteric liquid crystal layer in order to reduce double images caused by reflection of projection light on the front or back surface of a transparent substrate. Is preferably arranged. Thus, when light is incident obliquely, the center wavelength of selective reflection is shifted to the short wavelength side. Therefore, it is possible to adjust n × P so that λ calculated according to the above formula of λ = n × P is on the long wavelength side with respect to the wavelength of selective reflection required for the projected image display. preferable. In the cholesteric liquid crystal layer having a refractive index n ₂ , the central wavelength of selective reflection when a light ray passes at an angle of θ ₂ with respect to the normal direction of the cholesteric liquid crystal layer (the helical axis direction of the cholesteric liquid crystal layer) is λ _d . Λ _d is expressed by the following equation.
λ _d = n ₂ × P × cos θ ₂

For example, when a cholesteric liquid crystal layer is used, light incident from the λ / 2 phase difference layer side at an angle of 45 ° to 70 ° with respect to the normal line of the projected image display portion in air having a refractive index of 1 is normally 1 .Lambda. / 2 retardation layer of about .45 to 1.80 is transmitted at an angle of 23.degree. To 40.degree. With respect to the normal line of the projected image display portion, and is incident on a cholesteric liquid crystal layer having a refractive index of about 1.61. Since light passes through the cholesteric liquid crystal layer at an angle of 26 ° to 36 °, n × P may be adjusted by inserting this angle and the center wavelength of the desired selective reflection into the above equation.
Since the pitch of the cholesteric liquid crystal phase depends on the type of chiral agent used together with the polymerizable liquid crystal compound or the concentration of the chiral agent, the desired pitch can be obtained by adjusting these. For the method of measuring spiral sense and pitch, use the methods described in “Introduction to Liquid Crystal Chemistry Experiments”, edited by the Japanese Liquid Crystal Society, Sigma Publishing 2007, page 46, and “Liquid Crystal Handbook”, Liquid Crystal Handbook Editing Committee, page 196. be able to.

  By adjusting the central wavelength of selective reflection of the cholesteric liquid crystal layer to be used according to the emission wavelength range of the light source used for projection and the usage mode of the cholesteric liquid crystal layer, it is possible to display a clear projected image with high light utilization efficiency it can. In particular, by adjusting the central wavelength of selective reflection of each cholesteric liquid crystal layer according to the emission wavelength range of the light source used for projection, a clear color projection image can be displayed with high light utilization efficiency. Examples of usage of the cholesteric liquid crystal layer include an incident angle of projection light onto the cholesteric liquid crystal layer, a direction in which the projected image is observed, and the like.

  As the cholesteric liquid crystal structure, a cholesteric liquid crystal layer whose spiral sense is either right or left is used. The sense of the reflected circularly polarized light of the cholesteric liquid crystal structure coincides with the sense of the spiral. The spiral senses of the cholesteric liquid crystal structures having different center wavelengths of selective reflection may be the same or different, but are preferably the same.

The full width at half maximum Δλ (nm) of the selective reflection band showing selective reflection depends on the relationship of Δλ = Δn × P, where Δλ depends on the birefringence Δn of the liquid crystal compound and the pitch P. Therefore, the width of the selective reflection band can be controlled by adjusting Δn. Δn can be adjusted by adjusting the type and mixing ratio of the polymerizable liquid crystal compound or by controlling the temperature at the time of alignment fixation.
The half width Δλ of selective reflection may be 15 nm to 200 nm, 15 nm to 150 nm, 20 nm to 100 nm, or the like.

The cholesteric liquid crystal layer used in the present invention may be formed on a support. There is no limitation in particular as a support body, Various well-known support bodies can be used, Specifically, a glass substrate, a resin film, etc. are mentioned.
The support may be peeled off when the laminate is produced, or may be used as it is.

  In the laminate of the present invention, when a support is used, the support is preferably arranged so as to be on the second transparent substrate side. When the support has a phase difference, the influence on the light reflected by the functional layer can be reduced by using the second transparent substrate side. On the other hand, when a support having almost no phase difference is used, the first transparent substrate side may be used.

(Adhesive layer)
The adhesive layer used in the present invention is not particularly limited as long as it can adhere a transparent substrate and a functional layer. The adhesive layer on the first transparent substrate side is referred to as a first adhesive layer, and the adhesive layer on the second transparent substrate side is referred to as a second adhesive layer. The first adhesive layer and the second adhesive layer may be the same or different in material, thickness, and the like.

  In the present specification, the term “adhesive layer” means both the first adhesive layer and the second adhesive layer. The adhesive layer only needs to have the same shape and area as the first transparent substrate. As a contact bonding layer, a well-known contact bonding layer can be used as a sheet | seat used for the intermediate | middle layer of a laminated glass. The adhesive layer contains a resin as a main component. The main component refers to a component that occupies a ratio of 50% by mass or more of the interlayer sheet.

  The resin is preferably a synthetic resin. For example, the resin may be a thermoplastic resin. Examples of the thermoplastic resin include thermoplastic resins that have been used for intermediate layers of laminated glass. For example, polyvinyl acetal, polyvinyl chloride, saturated polyester, polyurethane, ethylene-vinyl acetate copolymer, ethylene -Ethyl acrylate copolymer etc. are mentioned. Among these, polyvinyl acetal is preferable from the viewpoints of transparency, strength, light resistance, and the like.

  Polyvinyl acetal is a general term for resins obtained by acetalizing polyvinyl alcohol with an aldehyde in the presence of an acid. For example, polyvinyl formal obtained by acetalization using formalin (formaldehyde 37% aqueous solution) as an aldehyde and butanol (butyl alcohol) as an aldehyde. Examples include acetalized polyvinyl butyral (hereinafter sometimes referred to as “PVB”).

  Of the above resins, polyvinyl butyral or ethylene-vinyl acetate copolymer is preferable, and polyvinyl butyral is more preferable. As described above, polyvinyl butyral can be obtained by acetalizing polyvinyl alcohol with butyraldehyde. The preferable lower limit of the degree of acetalization of the polyvinyl butyral is 40%, the preferable upper limit is 85%, the more preferable lower limit is 60%, and the more preferable upper limit is 75%.

Polyvinyl alcohol is usually obtained by saponifying polyvinyl acetate, and polyvinyl alcohol having a saponification degree of 80 to 99.8 mol% is generally used.
Moreover, the preferable minimum of the polymerization degree of the said polyvinyl alcohol is 200, and a preferable upper limit is 3000. When the polymerization degree of polyvinyl alcohol is 200 or more, the penetration resistance of the obtained laminated glass is difficult to decrease, and when it is 3000 or less, the moldability of the resin film is good, and the rigidity of the resin film does not increase too much. Good workability. A more preferred lower limit is 500, and a more preferred upper limit is 2000.

The resin is also preferably plasticized by the addition of a plasticizer. For example, as the plasticizer, phosphate ester, carboxylic acid ester, sugar ester, polycondensation ester, or the like is used.
The addition amount of the plasticizer is preferably 10 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the resin. By adding 10 parts by mass or more of a plasticizer, the thermoplastic resin can be sufficiently plasticized. Moreover, the intensity | strength of a resin layer can fully be maintained by the addition amount of a plasticizer being 80 mass parts or less.

  In addition to the plasticizer, the adhesive layer or the composition for forming the adhesive layer includes infrared shielding fine particles, an adhesion modifier, a coupling agent, a surfactant, an antioxidant, a heat stabilizer, a light stabilizer, One type or two or more types of various additives such as an ultraviolet absorber, a fluorescent agent, a dehydrating agent, an antifoaming agent, an antistatic agent, and a flame retardant may be included.

  The thickness of the adhesive layer is preferably, for example, 0.1 mm to 1.5 mm, and more preferably 0.2 mm to 1.0 mm.

<Laminated glass>
You may use the laminated body of this invention as a laminated glass. That is, the first transparent substrate and the second transparent substrate are used as glass substrates, respectively, and the first glass substrate and the second glass substrate are bonded through the first adhesive layer and the second adhesive layer. Can be used as At this time, the functional layer may be disposed on the entire surface of the first glass substrate, or may be disposed on a part thereof.

<Windshield glass>
The laminate and laminated glass of the present invention may be used as windshield glass. Windshield glass means window glass for vehicles such as cars, trains, airplanes, ships, playground equipment and the like. The windshield glass is preferably a windshield in the direction of travel of the vehicle. The windshield glass is preferably a vehicle windshield.

  In the present invention, when used as a windshield glass, it is preferable to arrange the first transparent substrate on the indoor side and the second transparent substrate on the outside light side.

<Video display system>
FIG. 2 shows an example of the video display system of the present invention. The video display system of the present invention is a video display system having the laminate 10, laminated glass or windshield glass of the present invention, and a video source 300. At this time, it is preferable that the first transparent substrate 1 be on the image source 300 side, that is, the projection light from the image source 300 should be disposed so as to pass through the first transparent substrate 1. In other words, it is preferable to arrange the second transparent substrate 6 side to be the outside light side.

[Video source]
The video source may itself be a device that displays an image, or it may be a device that emits light that can draw an image. In the video source, the light from the light source may be adjusted by a drawing method such as an optical modulator, laser luminance modulation means, or light deflection means for drawing. In this specification, the image source means a device including a light source and further including a light modulator, a laser luminance modulation unit, a light deflection unit for drawing, or the like depending on a drawing method.

{light source}
The light source is not particularly limited, and LEDs (including light emitting diodes and organic light emitting diodes (OLED)), discharge tubes, laser light sources, and the like can be used. Of these, LEDs and discharge tubes are preferred. This is because it is suitable for a light source of an image source that emits linearly polarized light. Of these, LEDs are particularly preferred. This is because LEDs are suitable for combination with a combiner using a cholesteric liquid crystal layer exhibiting selective reflection in a specific wavelength region, as will be described later, because the emission wavelength is not continuous in the visible light region.

{Drawing method}
The drawing method can be selected according to the light source to be used and the application, and is not particularly limited.
Examples of the drawing method include a fluorescent display tube, a liquid crystal display (LCD) method using liquid crystal and a liquid crystal on silicon (LCOS) method, a DLP (digital light processing) method, and a scanning method using a laser. Etc. The drawing method may be a method using a fluorescent display tube integrated with a light source.

In the LCD method and the LCOS method, light of each color is modulated and combined by an optical modulator, and light is emitted from a projection lens.
The DLP system is a display system using DMD (Digital Micromirror Device), and is drawn by arranging micromirrors for the number of pixels, and light is emitted from a projection lens.
The scanning method is a method in which a light beam is scanned on a screen and an image is contrasted using an afterimage of an eye. For example, the descriptions in JP-A-7-270711 and JP-A-2013-228664 can be referred to. In the scanning method using laser, laser light of each color (for example, red light, green light, and blue light) whose luminance is modulated is bundled into one light beam by a multiplexing optical system or a condenser lens, and the light beam is light. It only needs to be scanned by the deflecting means and drawn on an intermediate image screen described later.

  In the scanning method, the luminance modulation of laser light of each color (for example, red light, green light, and blue light) may be performed directly as a change in intensity of the light source, or may be performed by an external modulator. Examples of the light deflection means include a galvanometer mirror, a combination of a galvanometer mirror and a polygon mirror, or MEMS (microelectromechanical system). Among these, MEMS is preferable. Examples of the scanning method include a random scan method and a raster scan method, but it is preferable to use a raster scan method. In the raster scan method, the laser beam can be driven by a resonance frequency in the horizontal direction and a sawtooth wave in the vertical direction, for example. Since the scanning system does not require a projection lens, the apparatus can be easily downsized.

  The outgoing light from the video source may be linearly polarized light or natural light (non-polarized light). The outgoing light from the video source included in the head-up display system is preferably linearly polarized light. In an image source that uses an LCD or LCOS drawing system and a laser light source, the emitted light is essentially linearly polarized light. When the output light is a linearly polarized image source and the output light includes light of a plurality of wavelengths (colors), the polarization directions (transmission axis directions) of the polarization of the plurality of lights are the same or orthogonal to each other. It is preferable. Some commercially available video sources are known to have non-uniform polarization directions in the wavelength ranges of red, green, and blue light (see Japanese Patent Application Laid-Open No. 2000-212449). Specifically, an example in which the polarization direction of green light is orthogonal to the polarization direction of red light and the polarization direction of blue light is known.

{Intermediate image screen}
As noted above, the video source may use an intermediate image screen. In this specification, an “intermediate image screen” is a screen on which an image is drawn. That is, when the light emitted from the video source is not yet visible as an image, the light source forms a visible image on the intermediate image screen by this light. The image drawn on the intermediate image screen may be projected onto the combiner by light transmitted through the intermediate image screen, or may be projected onto the combiner after reflecting off the intermediate image screen.

Examples of the intermediate image screen include a scattering film, a microlens array, and a screen for rear projection. When a plastic material is used as the intermediate image screen, if the intermediate image screen has birefringence, the polarization plane and light intensity of polarized light incident on the intermediate image screen are disturbed, and color unevenness is likely to occur in the combiner. However, the use of a retardation film having a predetermined phase difference can reduce the problem of color unevenness.
The intermediate image screen preferably has a function of spreading and transmitting incident light. This is because the projected image can be enlarged and displayed. As such an intermediate image screen, for example, a screen composed of a microlens array can be cited. The microarray lens used in the head-up display is described in, for example, Japanese Patent Application Laid-Open No. 2012-226303, Japanese Patent Application Laid-Open No. 2010-145745, and Japanese Patent Application Publication No. 2007-523369.
The projector may include a reflecting mirror that adjusts the optical path of the projection light formed by the video source.

  Regarding a head-up display system using a windshield glass, which is a laminated glass, as a projection image display member, JP-A-2-141720, JP-A-10-96874, JP-A-2003-98470, US Pat. No. 5013134, JP-T 2006-512622, and the like can be referred to.

  Laminated glass is particularly useful for a head-up display system that uses a laser, LED, OLED, or the like whose emission wavelength is not continuous in the visible light region in combination with a projector using a light source. This is because the central wavelength of selective reflection of the cholesteric liquid crystal layer can be adjusted according to each emission wavelength. Moreover, it can also be used for the projection of a display in which display light such as an LCD (Liquid Crystal Display) is polarized.

{Projection light (incident light)}
Incident light is preferably incident at an oblique incident angle of 45 ° to 70 ° with respect to the normal of the projected image display region. As a method of reducing the double image that occurs when the projection light is reflected on the front or back surface of the glass, the projection light (p-polarized light) is incident on the glass surface at a Brewster angle, and the reflected light from the glass surface approaches zero. is there. (For example, refer to Japanese translations of PCT publication No. 2006-512622). The Brewster angle at the interface between glass having a refractive index of about 1.51 and air having a refractive index of about 1 is about 56 °, and p-polarized light is incident within the above-mentioned angle range, so that incident light for displaying a projected image is displayed. The cholesteric liquid crystal layer has less reflected light from the surface of the λ / 2 retardation layer, and can display an image with less influence of a double image. The angle is preferably 50 ° to 65 °. At this time, the projected image is observed on the incident light plane side at an angle of 45 ° to 70 °, preferably 50 ° to 65 ° on the side opposite to the incident light with respect to the normal line of the λ / 2 retardation layer. Any configuration can be used.

Incident light may be incident on the cholesteric liquid crystal layer from the first retardation layer side and incident on the cholesteric liquid crystal layer via the first retardation layer. That is, the first retardation layer may be disposed on the incident side of the projection light with respect to the cholesteric liquid crystal layer. Further, the incident light may be incident from any direction, and may be determined according to the direction of the observer. For example, the incident light may be incident at an oblique incident angle as described above from the downward direction during use.
Further, the slow axis of the first retardation layer (for example, λ / 2 retardation layer) forms an angle of 40 ° to 65 ° with respect to the vibration direction of the incident p-polarized light (incident light incident surface). It is preferable that the angle is 45 ° to 60 °.

  As described above, it is preferable that the projection light at the time of projection image display on the head-up display is p-polarized light that vibrates in a direction parallel to the incident surface. When the output light of the projector is not linearly polarized light, it may be p-polarized by using a linearly polarizing film arranged on the output light side of the projector, or it may be p-polarized in the optical path from the projector to the laminated glass Good. As described above, for projectors whose polarization directions in the red, green, and blue light wavelength ranges are not uniform, the polarization direction is adjusted in a wavelength-selective manner, and p-polarized light is used in all color wavelength ranges. It is preferable to make it enter.

  Hereinafter, the present invention will be specifically described based on examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the present invention is not limited to the following examples.

[Example 1]
<Preparation of coating solution>
(Coating liquid for forming cholesteric liquid crystal layer)
The following components were mixed to prepare a coating solution for forming a cholesteric liquid crystal layer having the following composition.
-The following mixture 1 100 mass parts-The following compound A 0.05 mass parts-The following compound B 0.02 mass parts-Right-turning chiral agent LC756 (manufactured by BASF)
Adjustment / polymerization initiator IRGACURE OXE01 (BASF) according to the target reflection wavelength
1.0 part by mass / solvent (methyl ethyl ketone) Amount at which the solute concentration is 25% by mass

Mixture 1 (the following numerical value represents mass%)

Compound A

Compound B

  Coating liquids 1 and 2 were prepared by adjusting the formulation amount of the chiral agent LC-756 having the above coating liquid composition. Using each coating solution, a single layer of cholesteric liquid crystal layer was prepared on a peelable support in the same manner as in the preparation of the following functional layers, and the reflection characteristics were confirmed. The central reflection wavelength was as shown in Table 1 below.

(Phase difference layer forming coating solution)
The following components were mixed to prepare a coating solution for forming a retardation layer having the following composition.
-Mixture 1 100 parts by mass-Compound A 0.05 parts by mass-Compound B 0.01 parts by mass-Polymerization initiator IRGACURE OXE01 (manufactured by BASF)
1.0 part by mass / solvent (methyl ethyl ketone) Amount at which the solute concentration is 25% by mass

<Preparation of laminate of peelable support and functional layer>
(1) A PET film (Cosmo Shine A4100, thickness: 100 μm) manufactured by Toyobo Co., Ltd. was used as a peelable support (length 250 mm × width 280 mm), and the long side direction of the peelable support was used as a reference on one side. A rubbing process (rayon cloth, pressure: 0.1 kgf (0.98 N), rotation speed: 1000 rpm, conveyance speed: 10 m / min, number of reciprocations: 1 reciprocation) was performed in the direction rotated 30 ° clockwise.

(2) A coating solution for forming a retardation layer is applied to a rubbed surface of a PET film using a wire bar, dried and placed on a hot plate at 50 ° C., and an electrodeless lamp “D bulb manufactured by Fusion UV Systems Co., Ltd. (60 mW / cm) for 6 seconds to fix the liquid crystal phase to obtain a retardation layer having a thickness of 1.8 μm. At this time, the retardation of the retardation layer was measured by AxoScan (manufactured by Axometrics), and it was 350 nm. The coating liquid 1 is applied to the surface of the obtained retardation layer using a wire bar, dried and placed on a 75 ° C. hot plate, and applied to an electrodeless lamp “D bulb” (60 mW / cm) manufactured by Heraeus Co., Ltd. For 6 seconds to fix the cholesteric liquid crystal phase to obtain a cholesteric liquid crystal layer having a thickness of 0.6 μm. The same process was repeated using the coating liquid 2 on the surface of the obtained cholesteric liquid crystal layer, and a 1.0 μm layer of the coating liquid 2 was laminated. Thus, a laminated film having a functional layer composed of a retardation layer and two cholesteric liquid crystal layers was obtained. When the transmission spectrum of the laminated film was measured with a spectrophotometer (manufactured by JASCO Corporation, V-670), transmission spectra having selective reflection center wavelengths at 510 nm and 650 nm were obtained.

  On the functional layer side of the laminated film, a PVB (polyvinyl butyral) film having a thickness of 0.38 mm and a length of 300 mm × width of 300 mm manufactured by Sekisui Chemical Co., Ltd. was installed so that the laminated film did not protrude from the PVB film. Crimping was performed under conditions of 08 MPa and 1 hr.

<Production of laminated glass>
A PVB film of 0.38 mm thickness made by Sekisui Chemical Co., Ltd., cut to the same size on a first glass plate having a length of 300 mm × width of 300 mm and a thickness of 2 mm and a transmittance of 90%, is placed on the peelable support. The peeled laminated film was placed with the functional layer side (peeled surface) as the bottom surface, and a second glass plate having a length of 300 mm × width of 300 mm of 4 mm and a transmittance of 80% was placed thereon. After holding this at 90 ° C. and 10 kPa (0.1 atm) for 1 hour, it was heated in an autoclave (manufactured by Kurihara Seisakusho) at 115 ° C. and 1.3 Mpa (13 atm) for 20 minutes to remove bubbles. The laminated glass 1 of Example 1 was produced. The following evaluation was performed and the results are shown in Table 2.

[Example 2]
In the production of the laminated glass 1 of Example 1, instead of the peelable support, the following TAC film with an optical absorption layer was used, and instead of the second glass plate having a thickness of 4 mm and a transmittance of 80%, the thickness was 2 mm, A laminated glass 2 of Example 2 was produced in the same manner except that a second glass plate having a transmittance of 90% was used. The following evaluation was performed and the results are shown in Table 2.

<Preparation of TAC film with optical absorption layer>
With reference to WO2013 / 075032, an optical absorption layer was provided on a TAC film (manufactured by FUJIFILM Corporation, TD80UL) to produce an in-plane uniform ND filter. Here, the film thickness of the optical absorption layer was adjusted so that ND = 0.1 (transmittance 80%). Subsequently, an alignment film coating solution having the following composition was applied to the surface opposite to the optical absorption layer side with a # 16 wire bar coater at 28 mL / m ² . Then, it was dried for 60 seconds with warm air of 60 ° C. and for 150 seconds with warm air of 90 ° C. The formed film surface was rubbed with a rubbing roll in a direction parallel to the conveying direction at 1000 rpm to produce a TAC film with an optical absorption layer.
(Alignment film coating solution)
The following modified polyvinyl alcohol 10 parts by mass Water 370 parts by mass Methanol 120 parts by mass Glutaraldehyde (crosslinking agent) 0.5 parts by mass

[Comparative Example 1]
In the production of the laminated glass of Example 1, a comparative example was similarly performed except that a second glass plate having a thickness of 2 mm and a transmittance of 90% was used instead of the second glass plate having a thickness of 4 mm and a transmittance of 80%. 1 laminated glass 3 was produced. The following evaluation was performed and the results are shown in Table 2.

[Comparative Example 2]
In the production of the laminated glass of Example 1, instead of the first glass plate having a thickness of 2 mm and a transmittance of 90%, the second glass plate having a thickness of 4 mm and the transmittance of 80%, a second glass plate having a thickness of 2 mm and a transmittance of 85% A laminated glass 4 of Comparative Example 1 was produced in the same manner except that the first and second glass plates were used. The following evaluation was performed and the results are shown in Table 2.

[Comparative Example 3]
In the production of the laminated glass of Example 1, the laminated glass 5 of Comparative Example 3 was produced in the same manner except that the first glass plate and the second glass plate were replaced. The following evaluation was performed and the results are shown in Table 2.

<< Transmissivity >>
According to the transmittance measuring method described above, the transmittance on the first substrate side from the functional layer, the transmittance on the second substrate side from the functional layer, and the transmittance of the produced laminated glass were measured.

《External light reflection》
The produced laminated glass was arrange | positioned under sunlight, and the reflected light of sunlight was observed visually. The following evaluation criteria were evaluated in comparison with the laminated glass 3 of Comparative Example 2.
A: The glare is reduced as compared with the laminated glass 3 of Comparative Example 2.
B: Dazzle is equivalent to the laminated glass 3 of the comparative example 2.
C: Brighter than the laminated glass 3 of Comparative Example 2.

《Image visibility》
As shown in FIG. 2, p-polarized light was applied to the produced laminated glass from the first substrate side, and the display image was observed. The following evaluation criteria were evaluated in comparison with the laminated glass 3 of Comparative Example 2.
A: Brighter and better visibility than the laminated glass 3 of Comparative Example 2.
B: Visibility is equivalent to the laminated glass 3 of Comparative Example 2.
C: Darker than the laminated glass 3 of Comparative Example 2 and poor in visibility.

<Heat insulation>
The laminated glass produced was stuck on the opening part of the box-shaped structure which has an opening part on one surface. This structure was irradiated with sunlight from a direction with a solar radiation angle of 50 °, and the temperature of the black body panel installed inside the box was measured. The following evaluation criteria were evaluated in comparison with the laminated glass 3 of Comparative Example 2.
A: The temperature is lower than that of the laminated glass 3 of Comparative Example 2.
B: The temperature is equivalent to the laminated glass 3 of Comparative Example 2.
C: Temperature is higher than the laminated glass 3 of Comparative Example 2.

DESCRIPTION OF SYMBOLS 1 1st transparent substrate 2 1st contact bonding layer 3 Retardation layer 4 Functional layer which permeate | transmits a part of visible light, and reflects a part 5 2nd contact bonding layer 6 2nd transparent substrate 10 Laminated body 200 Long side Direction 300 Video source

Claims (11)

A first transparent substrate, a functional layer that transmits a part of visible light and reflects a part thereof, and a second transparent substrate,
When the transmittance on the first transparent substrate side from the functional layer is T1, and the transmittance on the second transparent substrate side from the functional layer is T2, the following formula (1) is satisfied,
A laminate having a transmittance of more than 70%.
T1> T2 (1)
Here, the said transmittance | permeability says the value measured along the visible light transmittance | permeability test and procedure 1) as described in JISR3212 (2015).   The laminate according to claim 1, further comprising an adhesive layer between the first transparent substrate and the functional layer, and between the second transparent substrate and the functional layer.   The laminate according to claim 2, wherein each of the adhesive layers contains polyvinyl butyral and an ethylene-vinyl acetate copolymer.   The functional layer has any one of a cholesteric liquid crystal layer, a dielectric multilayer film layer, a reflective layer having a Fresnel lens, and a reflective layer having a half mirror shape. Laminated body. The laminated body as described in any one of Claims 1-4 which further satisfy | fills following formula (2).
T1-T2> 3% (2)   The laminate according to any one of claims 1 to 5, wherein at least one of the first transparent substrate and the second transparent substrate is a glass substrate.   The laminate according to claim 6, wherein both the first transparent substrate and the second transparent substrate are glass substrates.   The laminate according to claim 7, wherein the first transparent substrate is colorless glass, and the second transparent substrate is colored glass.   The laminated glass which has a laminated body as described in any one of Claims 1-8. It has the laminated body as described in any one of Claims 1-8, or the laminated glass of Claim 9.
A windshield glass in which the second transparent substrate is disposed on the outside light side. The laminated body according to any one of claims 1 to 8, the laminated glass according to claim 9, or the windshield glass according to claim 10.
An image source for emitting image light,
An image display system in which the image source is arranged on the first transparent substrate side.