Transparent display system

Abstract

To provide a transparent display system realizing both a video display performance and an outward appearance.SOLUTION: In a transparent display system having a video projector and a projection image display member, the difference between an average reflectance R(12) at a wavelength of 400 to 700 nm when light is allowed to impinge on the projection image display member such that an angle to a normal line of a video display surface becomes 12° and an average reflectance Rmax(60) at a wavelength of 400 to 700 nm when P waves are allowed to impinge on the projection image display member such that an angle to a polarization axis that is an azimuth in which the reflectance of P waves is maximized becomes 60° becomes 5% or larger, and the difference between the Rmax(60) and the average reflectance Rmin(60) at a wavelength of 400 to 700 nm when P waves are allowed to impinge on the projection image display member such that an angle to an azimuth orthogonal to the polarization axis becomes 60° becomes 5% or larger.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a transparent display system, a head-up display system, a manned transportation system, and a screen that are excellent in image display performance and appearance. [Background technology]

[0002] A transparent display system is a system that displays an image on a transparent projection member, and its simplest mechanism is to project light that forms the source of the image (hereinafter sometimes referred to as image light) onto the projection unit from an oblique direction, reflect it, and bring the reflected image into the user's field of vision. An example of a transparent display system is a head-up display system that displays route information, warning information, building information, etc. that matches the scenery in front of the passenger on the windshield of a manned vehicle.

[0003] A known configuration of a projection component is one in which a reflective layer is provided on part of the windshield, and an example of a reflective layer is a nanofilm including a dielectric layer and a metal layer, as shown in Patent Document 1. Although such nanofilms have excellent reflectivity of image light, their reflectivity is isotropic in-plane, meaning that they have a certain level of reflectivity regardless of the azimuth angle from which the image light is incident. As a result, when looking at the windshield from the passenger seat or outside the vehicle, the areas where the nanofilm is present may appear colored and stand out.

[0004] To solve this problem, Patent Document 2 shows an example of using a polarized reflective film as a reflective layer with in-plane anisotropy in reflectivity. Polarized reflective films have in-plane directions where the reflectivity of P waves is maximum and minimum, and by aligning the direction where the reflectivity of P waves is maximum with the direction of the P waves of the image light, the image display quality can be improved, while there is also a direction where the reflectivity of P waves is minimum, so overall it is possible to suppress coloring more than the nanofilm disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2017-538141 [Patent Document 2] Special Publication No. 2006-512622 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the polarized reflective film disclosed in Patent Document 2 has a constant reflectance whether the light that forms the image is irradiated from the front or from an oblique angle, so in order to ensure image displayability, it needs to be designed to have a certain level of reflectance, but as a result, coloring becomes noticeable when viewed from the driver, making the display look poor. Therefore, an object of the present invention is to provide a transparent display system that achieves both image displayability and good appearance. [Means for solving the problem]

[0007] The present invention has been made to solve the above-mentioned problems and has the following configuration: That is, the transparent display system includes an image projector that irradiates light to project an image, and a projection image display member on which an image is projected by the light from the image projector, wherein the difference between the average reflectance R(12) at wavelengths of 400 nm to 700 nm when light is incident on the projection image display member so that the angle it forms with a normal to the image display surface is 12° and the average reflectance Rmax(60) at wavelengths of 400 nm to 700 nm when P waves are incident on the projection image display member so that the angle they form with the polarization axis, which is the orientation at which the reflectance of P waves is maximum, is 5% or more, and the difference between Rmax(60) and the average reflectance Rmin(60) at wavelengths of 400 nm to 700 nm when P waves are incident on the projection image display member so that the angle they form with the orientation orthogonal to the polarization axis is 60° is 5% or more.

[0008] The transparent display system of the present invention can also be configured as follows, and can also be used in a head-up display system, manned transportation, and screen as described below. (1) A transparent display system comprising an image projector that projects an image by irradiating light, and a projection image display member on which an image is projected by the light from the image projector, characterized in that the difference between the average reflectance R(12) at wavelengths of 400 nm to 700 nm when light is incident on the projection image display member so that the angle it forms with the normal to the image display surface is 12° and the average reflectance Rmax(60) at wavelengths of 400 nm to 700 nm when P waves are incident on the projection image display member so that the angle they form with the polarization axis, which is the orientation at which the reflectance of P waves is maximum, is 5% or more, and the difference between the Rmax(60) and the average reflectance Rmin(60) at wavelengths of 400 nm to 700 nm when P waves are incident on the projection image display member so that the angle they form with the orientation perpendicular to the polarization axis is 60° is 5% or more. (2) The transparent display system according to (1), wherein R(12) is 30% or less. (3) The transparent display system according to (1) or (2), wherein the Rmax(60) is 20% or more. (4) A transparent display system according to any one of (1) to (3), characterized in that the angle between the polarization axis and the direction in which the P wave of the light emitted from the image projector is maximum is between 0° and 20°. (5) The transparent display system according to any one of (1) to (4), wherein the retardation of the projection image display member is greater than 2000 nm. (6) A transparent display system described in any one of (1) to (5), wherein the projection image display member has a structure in which a transparent hard material and a light-reflecting material are laminated at least in part via an adhesive layer, and the light-reflecting material is located on the light incident surface of the projection image display member. (7) The transparent display system according to any one of (1) to (6), wherein the projection image display member has a total haze of 1.0% or less. (8) The transparent display system according to any one of (1) to (7), further comprising a protective layer on the outermost surface of the projection image display member. (9) The transparent display system according to any one of (1) to (8), wherein the arithmetic mean roughness of the light incident surface of the projection image display member is 0.90 nm or less. (10) A transparent display system according to any one of (1) to (9), wherein the crack initiation pressure obtained by measuring the light incident surface of the projection image display member using a microscratch test method in accordance with JIS R-3255:1997 is 100 GPa or more and 600 GPa or less. (11) The transparent display system according to any one of (1) to (10), wherein at least one low refractive index layer having a refractive index of 1.50 or less is present on the light incident surface side of the projection image display member. (12) The transparent display system according to (11), wherein the product n×d of the refractive index n and the layer thickness d of the low refractive index layer is 150 nm or more and 250 nm or less. (13) A transparent display system according to any one of (1) to (12), wherein the difference between the maximum and minimum values of retardation at point C, point X1, point X2, point Y1, and point Y2 is 1000 nm or less, when the center point of the projection image display member is point C, the midpoint between point C and the upper end is point X1, the midpoint between point C and the lower end is point X2, the midpoint between point C and the left end is point Y1, and the midpoint between point C and the right end is point Y2. (14) A transparent display system according to any one of (1) to (13), wherein, when the center point of the projection image display member is defined as point C, the midpoint between point C and the upper end is defined as point X1, the midpoint between point C and the lower end is defined as point X2, the midpoint between point C and the left end is defined as point Y1, and the midpoint between point C and the right end is defined as point Y2, the angles formed between each polarization axis and the direction in which the P wave of the light irradiated from the image projector is maximum at point C, point X1, point X2, point Y1, and point Y2 are between 0° and 20°. (15) The transparent display system according to any one of (6) to (14), wherein the light-reflecting material is a laminated film in which at least two types of thermoplastic resin layers are laminated in 51 or more layers. (16) A head-up display using the transparent display system according to any one of (1) to (15). (17) A manned transportation vehicle equipped with the transparent display system according to any one of (1) to (15) or the head-up display according to claim 17. (18) A screen using the transparent display system according to any one of (1) to (15). [Effects of the Invention]

[0009] The present invention can solve the above problems and provide a transparent display system that achieves both good image display performance and good appearance. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram illustrating one embodiment of a transparent display system of the present invention. [Figure 2] 1 is a schematic diagram illustrating one embodiment of a projection image display member that can be used in the transparent display system of the present invention. [Figure 3] 3 is a schematic diagram illustrating point C of a projection image display member that constitutes the transparent display system of the present invention. FIG. [Figure 4] 2 is a schematic diagram illustrating points X1, X2, Y1, and Y2 of a projection image display member that constitutes the transparent display system of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes embodiments of the present invention, but the present invention should not be construed as being limited to the embodiments including the following examples, and various modifications are naturally possible within the scope of achieving the object of the invention and not departing from the gist of the invention.

[0012] The transparent display system of the present invention is a transparent display system including an image projector that projects an image by irradiating light, and a projection image display member onto which an image is projected by the light from the image projector.

[0013] In the present invention, a transparent display system refers to a display system in which the projection image display member is transparent from the viewpoint of an observer, and the image displayed on the projection image display member by light emitted from an image projector and the scenery behind the projection image display member can be viewed simultaneously and superimposed. In this case, "transparent" refers to an average transmittance of 50% or more for light in the visible light range (400 to 700 nm) incident at an angle of 60° to the normal direction of the image display surface, assuming that the projection image display member is positioned at an installation angle for actual use and the image projection portion is viewed from the observer's line of sight. The method for determining transparency will be described in detail later.

[0014] The projection image display member is not particularly limited as long as it has the above characteristics, but a laminated structure of a transparent hard material and a light-reflecting material is preferred. Furthermore, when projecting an image over a wide area of the projection image display member and superimposing it on a landscape, it is preferable that the above requirements be met across the entire projection area. The "transparency" of a projection image display member is determined by analyzing the average transmittance in the visible light range according to a transmission spectrum measurement using a spectrophotometer, as described below. Specifically, a projection image display member is considered "transparent" if it satisfies the above requirements at all five points: the center point C of the projection image display member, as described below; the midpoint between point C and the upper end (point X1); the midpoint between point C and the lower end (point X2); the midpoint between point C and the left end (point Y1); and the midpoint between point C and the right end (point Y2).

[0015] An example of such a transparent display system is an image display device as shown in Figure 1. In the transparent display system of Figure 1, light 2 that forms the basis of an image (light for the image) is irradiated from an image projector 1 onto a projection image display member 3, and the image is projected onto the projection image display member 3. This allows an observer 5 of the transparent display system to view the image superimposed on the surrounding scenery 4. Note that reference numeral 6 indicates the angle of incidence of the light for the image from the image projector to the projection image display member.

[0016] The transparent display system of this embodiment can be used as a head-up display (HUD) for manned transportation, as a transparent screen for spatial presentation in amusement applications, or as electronic signage applications such as signage and show windows. Manned transportation refers to transportation means such as vehicles, trains, airplanes, and ships, either driven by a person or operated unmanned with passengers. In manned transportation, the transparent display system of the present invention can be used as a head-up display that allows the driver to simultaneously view the scenery outside the vehicle window while superimposing speed displays, navigation information, and the like. The transparent display system of the present invention can also be preferably used in signage applications in manned transportation, allowing passengers to view information superimposed on the scenery outside the vehicle window.

[0017] The image projector constituting the transparent display system of the present invention can be a typical image projector, such as a liquid crystal projector, RGB laser, DLP (Digital Light Processing), LCOS (Liquid Crystal on Silicon), liquid crystal, organic electroluminescence (EL), micro LED, or mini LED, when projecting an image at a single focus. Alternatively, an image projector capable of multifocal display can be used to simultaneously project images at different focuses, reducing the viewer's eye movement. In this case, a mirror reflection type image projector, which combines a reflective mirror and a magnifying mirror separately from the light-emitting device inside the image projector body, or a light guide type image projector, which emits light from the light-emitting device into a light guide member and converts the emission angle and emission range of the light beam before projecting, can be used. These image projectors can be freely selected based on the installation location, installation space capacity and installation angle, the image projection position on the projection display member, the brightness, color gamut, and viewing angle of the resulting image.

[0018] It is preferable that the light emitted from the image projector is directly irradiated from the exit surface of the image projector onto the projection surface of the projection image display member. The image from the image projector of the present invention is preferably an image using P waves in order to reduce overlapping images and achieve clear display when wearing polarized sunglasses. Here, an image using P waves refers to an image projected onto a projection image display member by light whose P wave intensity is greater than that of S waves entering the projection image display member. Furthermore, P waves refer to electromagnetic waves whose electric field component is parallel to the plane of incidence (in other words, linearly polarized light that oscillates parallel to the plane of incidence), and S waves refer to electromagnetic waves whose electric field component is perpendicular to the plane of incidence (in other words, linearly polarized light that oscillates perpendicular to the plane of incidence).

[0019] When the light of an image incident on a projection image display component contains S-waves, reflections occur on the front and back surfaces of the component, resulting in the appearance of overlapping images. However, when P-waves are incident at an angle of incidence near the Brewster angle, almost no reflection occurs on the front and back surfaces of the component. Furthermore, by including a large proportion of P-wave components in the light of an image incident on a projection image display component, it is possible to prevent a decrease in the brightness of the displayed image even when wearing polarized sunglasses. Polarized sunglasses are designed to block S-wave components to ensure a clear field of view by suppressing glare from the ground or windshield, which are dominated by S-wave components when the ground or water surface is a reflective surface. Therefore, by including a large proportion of P-waves, which have a polarization direction 90° different from S-waves, the brightness of the displayed image can be maintained even when wearing polarized sunglasses. From these perspectives, the higher the proportion of P-wave components in the light of an image incident on a projection image display component, the better, preferably 90% or more, and even more preferably 99% or more. For the reasons mentioned above, there is no particular upper limit to the proportion of P-wave components in the light of the image incident on the projection image display member, and it is essentially 100%.

[0020] Furthermore, in transparent display systems, the viewer often views the image from a specific position. Therefore, in order to enable the viewer to view the image projected over a wide area, it is also preferable to project the image using multiple image projectors that deliver image light to the viewer from all angles by specular reflection. One of the features of the transparent display system of the present invention is that it can clearly display images without overlapping images, even when multiple image projectors are arranged in this way to provide wide-area and wide-viewing-angle visibility. Therefore, it is preferably used when the image needs to be viewed partially or entirely over a wide area of the projected image display member at the viewer's line of sight.

[0021] A specific example of such an embodiment is a head-up display for an automobile, in which two or more image projectors are arranged side by side on or inside the dashboard, displaying different images and information in tandem or independently. In this embodiment, the observer (driver) can see a wide range of information, such as speed display navigation information, typically displayed on the instrument panel, as well as signage such as nearby vehicle approach and hazard warnings, all at once. Furthermore, by projecting light beams of images with different focal points from multiple image projectors arranged in parallel, it is possible to effectively superimpose information on the depth of the scenery behind the projected image display component, allowing the observer to more visually recognize the information. While multiple image projectors can be arranged side by side in any direction, considering the space available for installing the image projectors and the change in incident angle depending on the installation position, it is preferable from a design perspective to arrange them side by side relative to the projected image display component.

[0022] A preferred embodiment of the projection image display member constituting the transparent display system of the present invention is, for example, an embodiment shown in Fig. 2, in which a transparent hard material and a light-reflecting material are laminated at least in part via an adhesive layer, with the light-reflecting material being located on the light incident surface of the projection image display member. In Fig. 2, reference numerals 7 to 9 respectively represent the light-reflecting material, adhesive layer, and transparent hard material. By using a projection image display member of this configuration, light can be directly irradiated from the image projector onto the light-reflecting material, allowing the viewer to view the image more clearly.

[0023] Suitable materials for use as the transparent hard material include glass and transparent resin substrates, with a thickness of 1 mm or more being preferred to ensure support. While there is no particular upper limit on the thickness of the transparent hard material, a thickness of 10 mm or less is preferred because excessive thickness unnecessarily increases the weight of the entire projection image display component. Glasses suitable for use as the transparent hard material include not only single-layer glass but also laminated and tempered glass used in automobile windshields, side windows, and rear windows, as well as plate glass, double-glazed glass, and vacuum glass used in building materials. Transparent resin substrates suitable for use as the transparent hard material include polyethylene terephthalate, polycarbonate, acrylic, polyvinyl chloride, polyethylene, polypropylene, polymethylpentene and its copolymers, and acrylonitrile-butadiene-styrene copolymers. These transparent resin substrates may be composed of a single component or a mixture of multiple components.

[0024] The transparent hard material and the light-reflective material can be laminated directly together using methods such as water lamination. However, due to concerns about peeling during use, it is preferable to laminate them via an adhesive layer 8 such as a pressure-sensitive adhesive or glue, as shown in Figure 2. Examples of suitable pressure-sensitive adhesives and glues include vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, ethylene-vinyl acetate copolymers, polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal, polyvinyl ether, nitrile rubber, styrene-butadiene rubber, natural rubber, chloroprene rubber, polyamides, epoxy resins, polyurethanes, acrylic resins, cellulose, polyvinyl chloride, polyacrylic esters, and polyisobutylene. These pressure-sensitive adhesives and glues can be used alone or in combination. To enhance functionality, viscosity adjusters, plasticizers, heat stabilizers, antioxidants, UV absorbers, antistatic agents, lubricants, colorants, crosslinking agents, and the like can be added.

[0025] These adhesives may be in liquid, gel, block, powder, film, etc. before processing. Adhesive solidification methods include solvent evaporation, moisture curing, heat curing, hardener mixing, anaerobic curing, ultraviolet curing, thermal melting and cooling, and pressure-sensitive. On the other hand, lamination methods include lamination molding, injection molding, vacuum molding, pressure molding, and combined vacuum and pressure molding. Projection image display components are produced by applying heat, pressure, and the above-mentioned adhesive solidification methods.

[0026] The transparent display system of the present invention requires that the difference between the average reflectance R(12) at wavelengths of 400 nm to 700 nm when light is incident on the projection image display member at an incident angle of 12° relative to the normal to the image display surface, and the average reflectance Rmax(60) at wavelengths of 400 nm to 700 nm when P waves are incident on the projection image display member at an incident angle of 60° relative to the polarization axis, which is the orientation at which the reflectance of P waves is maximum, is 5% or more.

[0027] Here, "light is incident on the projection image display member at an incident angle of 12° relative to the normal to the image display surface" means that the angle (incidence angle) between the normal to the projection image display member and the direction of light propagation is 12°. 12° is the minimum incident angle at which reflectance can be measured, and the reflectance of light under this condition can be treated as approximately equivalent to the reflectance of light incident from the front. R(12) is the reflectance when light is incident from approximately the front of the projection image display member and is an index that affects the overall coloring of the projection image display member, i.e., the conspicuousness of the light-reflecting material that makes up the projection image display member. 60° is an example of the incident angle when projecting an image onto the projection image display member, and Rmax(60) is the maximum reflectance when light is incident on the projection image display member surface from each direction at an incident angle of 60°. In a preferred embodiment of the transparent display system of the present invention, P-wave light is projected so that the incident plane is parallel to the polarization axis. In this case, Rmax(60) corresponds to the reflectance of the light of the image on the projection image display member.

[0028] R(12) can be measured using a known spectrophotometer, and the details of the measurement method will be described later. Rmax(60) and Rmin(60), which will be described later, can be measured using a known spectrophotometer by specifying the polarization axis (described later) and adjusting the angle of incidence based on this. The details of the measurement method will be described later.

[0029] As mentioned above, R(12) and Rmax(60) can be considered the difference between the reflectance of light from the front and the reflectance of P-wave light emitted from the image projector, and by making the difference between R(12) and Rmax(60) 5% or more, both image display performance and appearance (the light-reflective material being less noticeable) can be achieved. From the above perspective, a larger difference between R(12) and Rmax(60) is preferable, with a difference of 10% or more being preferable. The upper limit of the difference between the two is 80% from a feasible perspective. On the other hand, if the difference between R(12) and Rmax(60) is less than 5%, the image display performance may deteriorate and the light-reflective material may become more noticeable.

[0030] The polarization axis can be identified using the following procedure, and the details of this method are described below (the measurement device may be replaced with one capable of similar measurements). First, the in-plane orientation axis azimuth at an incident angle of 0° is measured using a phase difference measurement device (KOBRA-21ADH) manufactured by Oji Scientific Instruments. Next, a Hitachi spectrophotometer (U-4100 Spectrophotometer) is fitted with an attached angle-variable reflection unit and a Glan-Taylor polarizer. The orientation axis direction of the projection image display component is set as an azimuth angle of 0°, and the film is rotated clockwise from 0° to 10° in 1° increments and counterclockwise from 1° to 10° in 1° increments. The reflectance of P waves in the wavelength range of 400 to 700 nm at an incident angle θ = 60° from each azimuth angle direction relative to the normal to the film surface is measured in 1 nm increments for 21 conditions. From the obtained reflectance, the azimuth angle direction that gives the maximum average reflectance of P waves in the wavelength range of 400 nm to 700 nm at an incident angle of 60° in each azimuth angle direction is defined as the polarization axis.

[0031] Here, as a method for making the difference between R(12) and Rmax(60) 5% or more, a method of using a laminated film as a light-reflecting material, which will be described below, is exemplified. Hereinafter, a laminated film will be described as an example of a material that can be suitably used as a light-reflecting material.

[0032] The laminated film used as a light-reflecting material preferably has a structure in which a plurality of different thermoplastic resin layers are regularly laminated. Here, "different thermoplastic resin layers" means that the thermoplastic resin layers have different compositions and refractive indices that differ by 0.01 or more in any of the directions of the orientation axis, the direction perpendicular to the orientation axis in the film plane, and the direction perpendicular to the film plane.

[0033] "Different compositions" means that the components constituting the thermoplastic resin layer differ by 1% by mass or more, preferably the main component. The orientation axis direction refers to the direction in the film plane with the highest refractive index. This can be determined by a known measurement method, such as a molecular orientation analyzer MOA-8000 manufactured by Oji Instruments Co., Ltd. The refractive index in each direction of the outermost layer can be measured by a known method, such as the critical angle method, using an Abbe refractometer or a Prism Coupler SPA-400 manufactured by Cylon Technology Co., Ltd. Details of the measurement method when using the Prism Coupler SPA-400 manufactured by Cylon Technology Co., Ltd. will be described later. The main component refers to a component that accounts for more than 50% by mass but not more than 100% by mass, when all components constituting the layer are taken as 100% by mass.

[0034] The refractive index in each direction of layers other than the outermost layer can be determined as follows. Using the thickness of each layer of the laminate film and the refractive index of the thermoplastic resin layer constituting the outermost layer, an optical simulation of reflectance is performed by setting the refractive index of each layer other than the outermost layer to an arbitrary value. Next, from the results of the optical simulation and the reflectance measured using the measurement method described below, the average reflectance of each reflection band that is 10% or more continuously over 100 nm or more in wavelengths between 400 and 2000 nm is calculated. If the difference between the average reflectance and the average reflectance is within ±2%, this refractive index is defined as the refractive index of each layer other than the outermost layer. The thickness of each layer of the laminate film can be measured by observing a cross-section of a sample cut out with a microtome using a transmission electron microscope (TEM), such as the H-7100FA model (manufactured by Hitachi, Ltd.). Optical simulations can also be performed using a VBA program that uses the optical thin film characteristic matrix method (Mitsunobu Kohiyama (2006), Optical Thin Film Filter Design, Optronics Co., Ltd.). Details of the thickness measurement of each layer and the optical simulation are described below.

[0035] Furthermore, "regularly laminated" means that a plurality of different thermoplastic resin layers are laminated in a regular arrangement in the thickness direction. For the purpose of simplifying the explanation, some of the explanations will be given using as an example a laminate film having a configuration in which two different thermoplastic resin layers are alternately laminated, which is one of the preferred embodiments of the light-reflecting material for the transparent display system of the present invention. However, the same understanding should be given to the case in which three or more thermoplastic resin layers are used.

[0036] Specific examples of such an embodiment include a laminate film consisting of a layer (Layer A) primarily composed of a first thermoplastic resin and a layer (Layer B) primarily composed of a second thermoplastic resin, in which the layers are laminated in the order A(BA)n, B(AB)n (n is a natural number representing the number of repeating units, the same applies below). Furthermore, when the laminate film consists of Layer A, Layer B, and a layer (Layer C) primarily composed of a third thermoplastic resin, the arrangement is not particularly limited, but examples include a laminate film consisting of layers laminated in the order C(BA)nC, C(ABC)n, C(ACBC)n, etc.

[0037] By alternately laminating multiple thermoplastic resin layers with different optical properties, such as refractive index, it is possible to achieve interference reflection that selectively reflects light in a desired wavelength band due to the difference in refractive index between the layers in the in-plane direction, the difference in refractive index in the thickness direction, and the relationship between the layer thicknesses. This interference reflection can achieve higher reflectivity for light in a wider wavelength band as the number of layers increases and the thicknesses of the layers constituting the regular arrangement become more diverse, resulting in a laminate film that reflects light in a desired wavelength band. From this perspective, the number of layers in the laminate film is preferably 51 or more, more preferably 401 or more, and even more preferably 601 or more. While there is no upper limit to the number of layers, increasing the number of layers increases manufacturing costs due to the larger manufacturing equipment and deteriorates handleability due to the increased film thickness. Therefore, in reality, a practical range is 10,001 layers, and preferably 2,001 layers. Furthermore, it is preferable that the outermost layers on both sides be the same layer to facilitate adjustment of film formation conditions.

[0038] To achieve a difference between R(12) and Rmax(60) of 5% or more, it is preferable to use a method of adjusting the refractive index difference in the thickness direction between two thermoplastic resin layers in a laminate film used as a light-reflecting material. More specifically, it is preferable to set the refractive index difference to 0.040 or more. By adopting such an embodiment, a difference in light reflectance occurs at incident angles of 60° and 12°, and by increasing this refractive index difference, the difference between R(12) and Rmax(60) becomes even larger. From the above perspective, the refractive index difference is more preferably 0.050 or more, even more preferably 0.060 or more, and particularly preferably 0.100 or more. Note that the thickness direction refers to the direction perpendicular to the film surface. Methods for achieving the refractive index difference in the thickness direction of the two thermoplastic resin layers constituting the laminate film within the above-mentioned preferred range include, as will be described in detail below, selecting the thermoplastic resin that serves as the main component of each thermoplastic resin layer forming the laminate structure, adjusting the stretching ratio in each direction, and selecting the heat treatment temperature.

[0039] Furthermore, the transparent display system of the present invention requires that the difference between Rmax(60) and the average reflectance Rmin(60) at wavelengths of 400 nm to 700 nm when P waves are incident on the projection image display member so that the angle between Rmax(60) and the direction perpendicular to the polarization axis is 60° is 5% or more.

[0040] Rmin(60) is the reflectance when light is incident on the projection image display member from the direction in which the reflectance is minimum for P-wave incidence, i.e., the direction perpendicular to the polarization axis within the film plane. The smaller the Rmin(60), the lower the visibility of the light-reflecting material in the projection image display member, making it less noticeable. On the other hand, as mentioned above, Rmax(60) corresponds to the reflectance of light irradiated onto the projection image display member from the image projector. Therefore, the greater the difference between Rmax(60) and Rmin(60), the better the image display quality while reducing appearance defects such as discoloration caused by the light-reflecting material. In other words, the greater the difference between Rmax(60) and Rmin(60), the better the image display quality and the reduction of appearance defects. From this perspective, the difference between Rmax(60) and Rmin(60) is more preferably 10% or more, and even more preferably 12% or more. From this perspective, the greater the difference between Rmax(60) and Rmin(60), the better, but from a feasible perspective, the upper limit is 50%.

[0041] The difference between Rmax(60) and Rmin(60) can be achieved by adjusting the laminate structure and stretch ratio of the laminate film used as a projection image display member. More specifically, for example, in a laminate film having the above-mentioned laminate structure, polyethylene terephthalate or polyethylene naphthalate is used as the main component of one of the thermoplastic resin layers, and an amorphous resin having an ethylene terephthalate skeleton or an ethylene naphthalate skeleton as the main component of the other thermoplastic resin layer. The ratio of the stretch ratio in the width direction to the stretch ratio in the longitudinal direction (the stretch ratio in the width direction / the stretch ratio in the longitudinal direction, or the stretch ratio in the longitudinal direction / the stretch ratio in the width direction, which is a value greater than 1) is preferably 1.15 or more and 3.00 or less. Here, the "main skeleton" refers to the repeating unit that is most abundant among the repeating units constituting the resin. For example, in the case of polyethylene terephthalate, the main skeleton is the ethylene terephthalate skeleton. A stretching ratio of 1.15 or more ensures a sufficient difference in refractive index between the orientation axis direction and the in-plane direction perpendicular thereto, and the orientation axis direction is more uniform across the width of the film, making it difficult to visually recognize overlapping images even when images are displayed over a wide area. On the other hand, a stretching ratio of 3.00 or less prevents excessive orientation in a specific direction, reducing problems such as reduced film formability due to tearing and poor appearance during processing due to high heat shrinkage in the stretching direction. A more preferred stretching ratio that can achieve both uniform orientation and processability is 1.30 to 2.00, and even more preferably 1.50 to 2.00.

[0042] In the transparent display system of the present invention, R(12) is preferably 30% or less. An R(12) of 30% or less indicates that the average reflectance of the film at an incident angle of 12° for wavelengths of 400 to 700 nm is 30% or less. As described above, R(12) is a reflectance approximately equivalent to the reflectance when light is incident from the front of the image display surface. The wavelength band of 400 to 700 nm corresponds to the visible light range, and the low reflectance of light in this band suppresses coloring of the projection image display member and makes it less noticeable. Furthermore, the film exhibits excellent transmittance for external information such as scenery, thereby improving the visibility of such information. From the above perspectives, R(12) is preferably 20% or less, and more preferably 10% or less. To obtain such a transparent display system, it is effective to use a laminate film having the above-mentioned laminate structure as the light-reflecting material constituting the projection image display member and to reduce the difference in refractive index parallel to the film surface between two thermoplastic resin layers alternately laminated in the laminate film. If the difference in refractive index between the two thermoplastic resin layers in the direction parallel to the film surface is 0.04 or less, R(12) can be easily reduced to 30% or less, and if it is 0.02 or less, R(12) can be easily reduced to 20% or less. R(12) can also be reduced by providing a low refractive index layer (described later) on the surface of the projection image display member.

[0043] The transparent display system of the present invention preferably has an Rmax(60) of 20% or more. An Rmax(60) of 20% or more ensures sufficient brightness to make the image visible when the projection angle is 60° when P waves are irradiated onto the projection image display member to project the image. On the other hand, the higher the Rmax(60), the better the image display performance. However, if the Rmax(60) is too high, the transmittance of light projecting the background becomes excessively low, making it difficult to see the background. Therefore, the preferred upper limit is 50%. From the above viewpoints, the Rmax(60) is 20% or more and 50% or less, more preferably 20% or more and 40% or less, and even more preferably 20% or more and 33% or less.

[0044] To achieve an Rmax(60) of 20% or more and 50% or less, a laminate film having the aforementioned laminated structure can be used as the light-reflecting material of the projection image display member, and a method can be used in which the refractive index difference between the two thermoplastic resin layers in the laminate film in the direction perpendicular to the film surface is adjusted. More specifically, the refractive index difference is preferably 0.040 or more and 0.130 or less, and more preferably 0.040 or more and 0.120 or less. Furthermore, from the viewpoint of not impairing the visibility of the background, the refractive index difference between the two thermoplastic resin layers in the direction parallel to the film surface is preferably small, and the refractive index difference is preferably 0.020 or less.

[0045] In the transparent display system of the present invention, the angle between the polarization axis and the azimuth at which the P wave of the light irradiated from the image projector is maximized is preferably between 0° and 20°. Since the polarization axis is usually the azimuth at which the reflectivity of P wave is maximized, the smaller the angle between the polarization axis and the azimuth at which the P wave of the light irradiated from the image projector is maximized, the clearer the image will be displayed and the less unevenness in the display will be. From the above perspective, the angle is preferably between 0° and 10°, and more preferably between 0° and 5°. The polarization axis here refers to the polarization axis at the center point (point C, described in detail below) of the projection image display member. To set the angle between the polarization axis and the azimuth at which the P wave of the light irradiated from the image projector is maximized between 0° and 20° or within the above-mentioned preferred range, the polarization axis may be identified using the above-mentioned method, and then the projection image display member may be positioned so that the angle is within the desired range.

[0046] In the transparent display system of the present invention, the retardation of the projection image display member is preferably greater than 2000 nm. When a light-reflecting material is used for the projection image display member, the magnitude of the retardation is primarily determined by the retardation of the light-reflecting material. Retardation is a parameter related to the anisotropy of the orientation state; the higher the retardation, the greater the in-plane reflection anisotropy, making it possible to achieve both image display quality and reduced appearance defects (e.g., the less noticeable the light-reflecting material). From the above perspective, it is more preferable that the retardation of the projection image display member be 3000 nm or greater. Furthermore, by increasing the retardation of the projection image display member to greater than 2000 nm, it is possible to suppress color unevenness that would be visible when wearing polarized sunglasses for anti-glare purposes, due to the use of an oriented laminated film as the light-reflecting material for the projection image display member. The higher the retardation of the projection image display member, the better the image display performance and the less appearance defects there are, and the more color unevenness can be suppressed when wearing polarized sunglasses. However, if the retardation of the projection image display member is too high, the reflectance at the front in the orientation axis direction increases, and coloring can become more noticeable. From the above perspective, the retardation of the projection image display member is preferably 10,000 nm or less, and more preferably 5,000 nm or less. Note that retardation here refers to the retardation at point C described below, and the measurement method will be described in detail later.

[0047] As a method for increasing the retardation of the projection image display member to more than 2000 nm, for example, as described above, it is effective to use a laminated film whose orientation state is controlled by selecting the resin to be laminated and adjusting the stretching ratio in each direction as the light-reflecting material of the projection image display member.

[0048] Here, a method for producing a laminated film that can be suitably used as a light-reflecting material constituting a projection image display member of the transparent display system of the present invention will be described in detail, taking as an example an embodiment in which two thermoplastic resin layers are alternately laminated, although the laminated film is not limited to those obtained by the following method.

[0049] The laminated film has a structure in which a layer (Layer A) mainly composed of a first thermoplastic resin and a layer (Layer B) mainly composed of a second thermoplastic resin are alternately laminated, and the first thermoplastic resin is preferably a crystalline polyester resin (preferably polyethylene terephthalate or polyethylene naphthalate, etc.) and the second thermoplastic resin is preferably an amorphous polyester resin containing a structure derived from terephthalic acid or naphthalenedicarboxylic acid. Furthermore, the "amorphous polyester resin containing a structure derived from terephthalic acid or naphthalenedicarboxylic acid" is preferably a polyester resin in which 60 mol % to 100 mol % of the dicarboxylic acid components constituting the polyester resin are terephthalic acid and / or naphthalenedicarboxylic acid.

[0050] Furthermore, it is preferable that the basic skeletons of the first thermoplastic resin and the second thermoplastic resin are the same from the viewpoint of interlayer adhesion, etc. Here, the basic skeleton refers to the repeating unit that is contained most abundantly in terms of mole percent among the repeating units that constitute the molecular chain of the thermoplastic resin, and for example, in the case of polyethylene terephthalate, this corresponds to the ethylene terephthalate skeleton.

[0051] Here, the term "crystalline resin" refers to a thermoplastic resin obtained by heating the resin from 25 ° C. to 300 ° C. at a heating rate of 20 ° C. / min (1st RUN) according to JIS K7122 (1999) at a heating rate of 20 ° C. / min, holding the resin in that state for 5 minutes, then rapidly cooling it to a temperature of 25 ° C. or less, and then heating it again from room temperature to 300 ° C. at a heating rate of 20 ° C. / min. The crystalline resin has a crystalline fusion heat ΔHm calculated from the peak area of the melting peak in the differential scanning calorimetry chart obtained in the 2nd RUN. On the other hand, the term "amorphous resin" refers to a thermoplastic resin having a ΔHm of 5 J / g or less obtained by the above method, and more preferably a thermoplastic resin that does not exhibit a peak corresponding to crystalline melting.

[0052] The polyester resin, which is the main component of each layer of the laminate film, may contain structural units derived from the following dicarboxylic acid components or diol components. Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, and 4,4'-diphenylsulfonedicarboxylic acid. Examples of aliphatic dicarboxylic acids include adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, cyclohexanedicarboxylic acid, and their ester derivatives. These acid components may be used alone or in combination.

[0053] Examples of diol components include ethylene glycol, paraxylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2-bis(4-hydroxyethoxyphenyl)propane, isosorbate, spiroglycol, bisphenoxyethanolfluorene (BPEF), etc. These diol components may be used alone or in combination of two or more.

[0054] The reflective film can be manufactured by laminating thermoplastic resins, for example, by the following method. First, two types of thermoplastic resins (or thermoplastic resin compositions) are prepared in the form of pellets or the like. The pellets are dried in hot air or under vacuum as needed, and then fed into separate extruders. The thermoplastic resins are heated and melted in the extruders at a temperature above their melting point, and the resin is extruded with a gear pump or the like to equalize the extrusion rate. After that, foreign matter and denatured resins are removed using a filter or the like. Next, the two types of thermoplastic resins are fed into a multi-layer lamination device through separate flow paths and laminated alternately.

[0055] Multi-layer lamination devices such as multi-manifold dies, feed blocks, and static mixers can be used. It is particularly preferable to use a feed block with 51 or more, preferably 401 or more, and more preferably 601 or more fine slits. The use of such a feed block prevents the device from becoming excessively large, reduces the amount of foreign matter caused by thermal degradation, and enables high-precision lamination even when the number of layers is extremely large. Furthermore, lamination accuracy in the width direction is significantly improved compared to conventional technologies. Furthermore, with such a multi-layer lamination device, the thickness of each layer can be adjusted by the shape (length and width) of the slits, and the number of layers can be adjusted by the number of slits, making it easy to achieve any desired layer thickness or number. While the number of layers can be easily increased by increasing the number of slits, the upper limit of the number of slits is preferably 10,001, and more preferably 2,001, to avoid increasing the device size.

[0056] The laminated molten resin is then formed into a sheet using a die and extruded onto a cooling body such as a casting drum to be cooled and solidified to obtain a cast film. Preferably, a wire-, tape-, needle-, or knife-shaped electrode is used to bring the molten resin sheet into close contact with the cooling body such as a casting drum by electrostatic force, thereby rapidly solidifying the resin. The temperature and rotation speed of the casting drum are not particularly limited as long as the molten resin can be cooled and solidified, but a rotation speed of 20 to 40°C and 1 to 5 m / min are preferred.

[0057] The cast film thus obtained is preferably biaxially stretched. Here, biaxial stretching refers to stretching in the longitudinal direction and the width direction, where the longitudinal direction refers to the running direction of the film and the width direction refers to the direction perpendicular to the longitudinal direction within the film plane. Biaxial stretching may be performed by sequentially stretching in two directions (sequential biaxial stretching) or by simultaneously stretching in two directions (simultaneous biaxial stretching). Furthermore, if necessary, re-stretching may be performed in the longitudinal direction and / or the width direction. Sequential biaxial stretching will be described below.

[0058] In the case of sequential biaxial stretching, the stretching speed in the longitudinal direction is preferably 40 to 300% / sec, more preferably 50 to 150% / sec. Typically, stretching in the longitudinal direction (longitudinal stretching) is performed by the difference in peripheral speed between rolls, and the stretching ratio is preferably 1.5 to 5.0 times, more preferably 3.0 to 5.0 times, and even more preferably 3.3 to 5.0 times. The stretching temperature is preferably equal to or higher than the glass transition temperature of the thermoplastic resin having the lowest glass transition temperature, which is the main component of each layer constituting the casting film to be stretched, but not higher than a temperature 100°C higher than the glass transition temperature of the resin having the lowest glass transition temperature, and more preferably equal to or higher than a temperature 3°C higher than the glass transition temperature of the resin having the lowest glass transition temperature and not higher than a temperature 15°C higher than the glass transition temperature of the resin having the lowest glass transition temperature (however, the upper limit is set to be lower than the melting point of the resin having the lowest glass transition temperature).

[0059] Subsequently, the uniaxially stretched film obtained by longitudinal stretching is preferably stretched in the width direction (transverse stretching) at a stretching speed of 4 to 40% / sec, more preferably 4 to 30% / sec, and even more preferably 5 to 20% / sec. Stretching in the width direction is usually carried out using a tenter, with both widthwise ends of the uniaxially stretched film being held with multiple clips while being conveyed. The stretching ratio is preferably 1.5 to 6.5 times, more preferably 3.0 to 5.0 times, even more preferably 3.4 to 5.0 times, and particularly preferably 3.8 times or more and 5.0 times or less. Furthermore, the widthwise stretching temperature is preferably 7 to 20°C higher than the longitudinal stretching temperature.

[0060] As described above, the ratio of the stretch ratio in the width direction to the stretch ratio in the longitudinal direction (the ratio of the stretch ratio in the width direction to the stretch ratio in the longitudinal direction, or the ratio of the stretch ratio in the longitudinal direction to the stretch ratio in the width direction, which is greater than 1) is preferably 1.15 to 3.00. A more preferable stretch ratio that can achieve both uniformity of orientation and processability is 1.30 to 2.00, and even more preferably 1.50 to 2.00.

[0061] The sequentially biaxially stretched film is preferably heat-treated in a tenter at a temperature 50°C to 150°C higher than the stretching temperature, more preferably 170°C to 230°C. This allows for a film with the desired thermal shrinkage. In the first half of the heat treatment, additional stretching is performed in the width direction, preferably at a stretching ratio of 1.05 to 1.20. In the second half of the heat treatment, relaxation is preferably performed in both the longitudinal and width directions, preferably at a stretching ratio of 0.90 to 0.99 times (in other words, 1 to 10%) the film width immediately before relaxation. The laminated film thus obtained is then uniformly and gradually cooled to room temperature, after which the edge portions at both widthwise ends that were held by the tenter clips are cut and wound up. A roll of laminated film is thus obtained.

[0062] The transparent display system of the present invention preferably includes a protective layer on the outermost surface of the projection image display member. As described above, double images can be suppressed by laminating a light-reflecting material on the light incident surface side of the projection image display member. However, when the projection image display member is configured in this manner, deterioration due to wear can become an issue.

[0063] Therefore, forming a protective layer on the outermost surface of a projection image display member can improve abrasion resistance while maintaining the effect of reducing double images. Here, a protective layer refers to a layer located on the outermost surface of a projection image display member, in which more than 50% but not more than 100% by mass of the resin components constituting the layer are thermosetting or UV-curable resins. (However, if an inorganic-based layer is present on the outermost surface, this layer is treated as not present when identifying the protective layer.) Furthermore, if there are multiple consecutive layers from the outermost surface, in which more than 50% but not more than 100% by mass of the resin components constituting the layer are thermosetting or UV-curable resins, these layers are treated as a single protective layer. (In other words, the protective layer may have either a single-layer or multilayer structure.) Furthermore, if multiple types of thermosetting or UV-curable resins are used, the amount of each type of thermosetting or UV-curable resin is calculated by adding together all of the layers.

[0064] An example of a method for forming a protective layer on the outermost surface of a projection image display member is described below, but the protective layer formation method of the present invention is not limited to the embodiment described below. First, a coating composition containing a desired solvent, binder component, photopolymerization initiator, inorganic particles, and, if necessary, other additives, is applied to the outermost surface of a projection image display member that does not have a protective layer. The coating method can be a microgravure method or a die coating method, and it is preferable to apply the coating composition uniformly to the surface of the light-reflecting material. It is also preferable to apply the coating uniformly without unevenness using a coating wire bar, and the desired thickness can be achieved depending on the type and solids concentration of the coating composition.

[0065] Subsequently, the solvent is preferably evaporated from the coating composition in a drying step. Drying methods that can be used include heat transfer drying (contact with a hot object), convection heat transfer (hot air), radiation heat transfer (infrared rays), and others (microwaves, induction heating). The drying temperature, although depending on the type of solvent in the coating composition, is preferably within the range of room temperature to 200°C, more preferably 60°C to 200°C, and even more preferably 80°C to 150°C.

[0066] Subsequently, it is preferable to cure the protective layer. The curing method can be appropriately selected depending on the composition of the coating composition, etc. For example, it is preferable to use a method of irradiating with active energy rays, and as the active energy rays, ultraviolet rays (UV) or electron beams are preferred, and ultraviolet rays are more preferred. The light source of the active energy rays irradiated to thicken the coating film is not particularly limited, but for example, in the case of ultraviolet rays, light sources such as UV-LED lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, carbon arc lamps, xenon lamps, etc. may be used, and two or more of these may be used.

[0067] In the transparent display system of the present invention, the total haze of the projection image display member is preferably 1.0% or less. Because the projection image display member of this embodiment has excellent transparency, when the transparent display system is attached to the windshield or screen of a public transport vehicle, the background can be clearly seen. From the above perspective, the lower the total haze of the projection image display member, the more preferable, with 0.7% or less being more preferable, 0.6% or less being even more preferable, and 0.5% or less being particularly preferable. Since the lower the total haze, the better the transparency, there is no particular lower limit, but from the perspective of feasibility, the lower limit is 0.1% or less. The total haze of the projection image display member can be measured using a known haze meter, and the measurement method will be described in detail below.

[0068] One method for achieving the total haze within the above range for the projection image display member is to use the aforementioned laminate film as the light-reflecting material of the projection image display member and increase the transmittance of light from the normal direction of the laminate film. The methods for achieving this transmittance are as described above. Furthermore, when the projection image display member has a protective layer, optimizing the design of the protective layer is also effective. For example, reducing the amount of particles in the protective layer or reducing the average particle size of the particles in the protective layer is effective. Specifically, it is effective to set the particle amount in the protective layer to less than 0.1% by mass when the total components constituting the layer are taken as 100% by mass, or to set the average particle size of the particles to 60 nm or less when the particle amount is 0.1% by mass or more. Because light scattering increases the total haze, from this perspective, it is preferable that the protective layer does not contain components that induce light scattering, such as particles. However, particles can be added to the protective layer to improve abrasion resistance and hardness. To improve abrasion resistance and hardness while maintaining the total haze within the above range, it is preferable to set the particle amount and average particle size within the above range.

[0069] From the above viewpoints, the smaller the average particle size of the particles, the better, but the average particle size of the particles is more preferably 30 nm or less, and from the viewpoint of feasibility, the lower limit is 5 nm, and practically 10 nm is more preferable. When the average particle size of the particles is 60 nm or less, the particle concentration does not affect the total haze, but if the particle concentration of the protective layer is too high, the hardness becomes too high, reducing processability and increasing the occurrence of scratches due to particle shedding during wear, thereby worsening the abrasion resistance. From the above viewpoints and the definition of the protective layer described above, the particle concentration of the protective layer is preferably less than 50 mass%.

[0070] The particles contained in the protective layer are preferably inorganic particles, preferably at least one selected from the group consisting of metal elements, semimetal elements, and their oxides, nitrides, borides, carbonates, and sulfates, and more preferably oxide particles of at least one element selected from the group consisting of Si, Na, K, Ca, Mg, Ga, Zr, Ti, Al, In, Sb, Sn, and Ce. Specifically, silica (SiO), zirconium oxide (ZrO), titanium oxide (TiO), aluminum oxide (AlO), indium oxide (InO), zinc oxide (ZnO), tin oxide (SnO), antimony oxide (SbO), and indium tin oxide are preferred. These inorganic particles may be used alone or in combination.

[0071] In the transparent display system of the present invention, the arithmetic mean roughness of the light incidence surface of the projection image display member is preferably 0.10 nm or more and 0.90 nm or less. By adopting such an embodiment, the surface is smooth and therefore less susceptible to scratches due to rubbing. From the above viewpoint, the lower the arithmetic mean roughness of the light incidence surface of the projection image display member, the more preferable, with 0.70 nm or less being more preferable. From the viewpoint of feasibility, the lower limit is 0.10 nm, and 0.30 nm or more is more preferable. On the other hand, if the arithmetic mean roughness exceeds 0.90 nm, the surface becomes rough and is more susceptible to scratches due to rubbing.

[0072] When a projection image display member has a protective layer, the inorganic particle occupancy rate on the outermost surface of the protective layer and the average particle diameter in the protective layer affect the arithmetic mean roughness of the light-incident surface of the projection image display member. Therefore, to reduce the arithmetic mean roughness of the light-incident surface in such an embodiment, methods for reducing the arithmetic mean roughness of the protective layer can be used. More specifically, adjusting the particle concentration of the protective layer or the average particle diameter in the protective layer to a small value is effective. The arithmetic mean roughness can also be reduced by using an embodiment in which a light-reflecting material is located on the outermost surface without a protective layer, or by forming a low-refractive index layer (described below) on the surface of the light-reflecting material. The arithmetic mean roughness of the light-incident surface of the projection image display member can be measured using a known scanning white light interference microscope, such as a measuring device such as the "VertScan" (registered trademark) VS1540 manufactured by Hitachi High-Tech Science Corporation (details of the measurement method using this device will be described later).

[0073] In the transparent display system of the present invention, from the viewpoint of achieving both improved processability and reduced wear-related scratches, it is preferable that the crack initiation pressure measured by the microscratch test method conforming to JISR-3255:1997 on the light incident surface of the projection image display member be 100 GPa or more and 600 GPa or less. Here, the microscratch test method conforming to JISR-3255:1997 is a hardness quantification method in which a stylus with a diameter of several to several tens of micrometers is brought into contact with the outermost surface of the object to be measured, the load applied to the stylus is measured while increasing the load over time, and the point at which the load behavior changes abruptly when a scratch is made on the surface is taken as the crack initiation pressure (the detailed measurement method will be described later). The device for measuring the crack initiation pressure is not particularly limited as long as it is capable of measurement, but for example, a scratch tester (CSR5000 manufactured by Rhesca Co., Ltd.) can be used. Hereinafter, the "crack initiation pressure of the protective layer obtained by the microscratch test method conforming to JISR-3255:1997" will sometimes be referred to as the "crack initiation pressure."

[0074] Since the aforementioned protective layer typically has a higher hardness than the light-reflecting material, providing such a protective layer on the light incidence surface of the projection image display member is effective in maintaining the crack initiation pressure within the above range. A crack initiation pressure of 100 GPa or higher and 600 GPa can suppress the occurrence of scratches due to abrasion on the light incidence surface of the projection image display member while also improving processability. In a projection image display member having a protective layer on the light incidence surface side of the projection image display member, if the crack initiation pressure of the protective layer is 100 GPa or higher, the protective layer will have a certain level of hardness, thereby reducing the occurrence of scratches due to abrasion. From the above perspective, the crack initiation load of the protective layer is preferably 150 GPa or higher. Thus, from the perspective of reducing scratches due to abrasion, a higher crack initiation load of the protective layer is preferable, but as mentioned above, the trade-off between the crack initiation load and processability during heating must also be considered. From the perspective of maintaining good processability during heating, the upper limit of the crack initiation load of the protective layer is preferably 600 GPa, more preferably 500 GPa.

[0075] The crack initiation pressure of the protective layer can be controlled by adjusting the concentration of inorganic particles, which affects the hardness of the protective layer. By adjusting the inorganic particle concentration in the protective layer to 20% by mass or more and 60% by mass or less, the crack initiation pressure can be controlled to 100 GPa or 600 GPa or the preferred range described above. Furthermore, the solid components of the protective layer are highly dependent on the type of monomer (binder component) used to form the layer, and control can be achieved by selecting the type and concentration of the monomer.

[0076] Another method for measuring the hardness of the protective layer is pencil hardness measurement, but in this measurement, if the object to be measured is a multi-layer laminate, the adhesive layer or substrate, which has a lower hardness than the protective layer, is likely to be dented when the pencil lead is pressed against the object to be measured, and scratches are caused by a load lower than the hardness of the protective layer itself. On the other hand, the micro-scratch test method can measure the hardness of the outermost layer without being affected by the laminate structure, making it possible to more accurately measure the hardness of the protective layer itself.

[0077] The projection image display member included in the transparent display system of the present invention preferably includes a low-refractive index layer with a refractive index of 1.50 or less on the light incident surface side. By providing the low-refractive index layer, the reversed phases of the incident light and the reflected light cancel each other out, suppressing reflection on the surface of the projection image display member, thereby increasing the light transmittance mainly from the front and resulting in improved visibility of the scenery.

[0078] In the transparent display system of the present invention, the product n×d of the refractive index n and layer thickness d of the low refractive index layer is preferably 150 nm or more and 250 nm or less. By setting n×d to 150 nm or more and 250 nm or less, the reversed phases of incident light and reflected light cancel each other out, effectively suppressing reflection on the surface of the projection image display member, thereby increasing the light transmittance, mainly from the front. From the above perspective, n×d is preferably 50 nm or more and 200 nm or less, and more preferably 80 nm or more and 150 nm or less. n×d can be controlled within a suitable range by selecting the material of the low refractive index layer and adjusting its thickness.

[0079] The low refractive index layer is preferably located on the outermost surface of the projection image display member on the light incident side. The low refractive index layer may be formed directly on the light reflecting member, or a protective layer may be interposed between the low refractive index layer and the light reflecting member. By using a structure consisting of two or more layers with different refractive indices, it is possible to reduce the reflectance over a wide wavelength range of visible light.

[0080] Examples of materials for the low refractive index layer include silicon oxide, titanium nitride, magnesium fluoride, barium fluoride, calcium fluoride, hafnium fluoride, and lanthanum fluoride, and these can be used alone or in appropriate combination.

[0081] The method for providing the low refractive index layer on the outermost surface of the projection image display member is not particularly limited, and either a wet coating method or a dry coating method may be used.

[0082] Dry coating methods such as vacuum deposition, CVD, sputtering, and electron beam vapor deposition are also preferred because they can form thin films with uniform thickness. Among these, sputtering is preferred because it provides excellent uniformity in thickness and is easy to form dense films. In sputtering, a roll-to-roll system is used to continuously form thin films while transporting a long hard-coated film in one direction (longitudinal direction), thereby improving the productivity of anti-reflection films.

[0083] In order to achieve clear image display at a wide viewing angle over a wide range of the projection image display member, as in the transparent display system of the present invention, it is preferable that the retardation be uniform throughout the entire projection image display member. That is, in the transparent display system of the present invention, when the center point of the projection image display member is defined as point C, the midpoint between point C and the upper end is point X1, the midpoint between point C and the lower end is point X2, the midpoint between point C and the left end is point Y1, and the midpoint between point C and the right end is point Y2, it is preferable that the difference between the maximum and minimum values of retardation at points C, X1, X2, Y1, and Y2 is 1000 nm or less.

[0084] The following describes each position of the projection image display member (point C, point X1, point X2, point Y1, and point Y2). As shown in Figure 3, quadrilateral materials are often used for projection image display members. When the projection image display member is a flat rectangular shape, the intersection of the diagonal lines is defined as point C (reference numeral 10) as shown in Figure 3. Next, as shown in Figure 4, the midpoint between point C and the upper end is defined as point X1 (reference numeral 11), the midpoint between point C and the lower end is defined as point X2 (reference numeral 12), the midpoint between point C and the left end is defined as point Y1 (reference numeral 13), and the midpoint between point C and the right end is defined as point Y2 (reference numeral 14). Note that when the corners of the projection image display member are rounded or the projection image display member is a shape other than a quadrilateral, a rectangle that includes the projection image display member and has the smallest area can be drawn, and the points can be determined as described above. Furthermore, if the projection image display member is curved rather than flat, the point corresponding to the center of gravity of the material is defined as point C, and the midpoint of the curve connecting point C and the upper end is defined as X1 (similarly, points X2, Y1, and Y2 can also be determined).

[0085] As described above, retardation contributes to image display performance and appearance (e.g., the inconspicuousness of the light-reflective material) as seen by an observer (e.g., a driver or passenger). Therefore, it is preferable that the retardation variation be small in order to make these effects more uniform throughout the entire projection image display member. From the above viewpoint, the difference between the maximum and minimum retardation values is more preferably 500 nm or less. In order for the difference between the maximum and minimum retardation values to satisfy the above range, it is preferable to use the laminate film described above as the light-reflective material of the projection image display member of the present invention, and to set the manufacturing conditions as follows. First, among the above-mentioned preferable stretching conditions in the sequential biaxial stretching film formation, it is preferable to set the stretching ratio within the above-mentioned preferable range. In addition, it is effective to provide a temperature gradient in the stretching process in the width direction, provide a temporary low-temperature region before the heat treatment process, and go through a film formation process in which slight stretching is performed in the heat treatment process.

[0086] In order to achieve a clear display with a wide viewing angle over a wide range of the projection image display member, as in the transparent display system of the present invention, it is preferable to adjust the angle between the polarization axis at each position on the projection image display member and the azimuth at which the P wave of the light irradiated from the image projector is maximized. That is, in the transparent display system of the present invention, when the center point of the projection image display member is defined as point C, the midpoint between point C and the upper end is point X1, the midpoint between point C and the lower end is point X2, the midpoint between point C and the left end is point Y1, and the midpoint between point C and the right end is point Y2, it is preferable that the angle between each polarization axis and the azimuth at which the P wave of the light irradiated from the image projector is maximized at points C, X1, X2, Y1, and Y2 is between 0° and 20°.

[0087] Points C, X1, X2, Y1, and Y2 can be determined as described above. Since the polarization axis is the orientation at which the reflectance of P waves is maximized, if the angle between the polarization axis and the orientation at which the P waves of the light irradiated from the image projector are maximized at the above five points is small, a clear image can be displayed over a wide range of the projection image display component with a wide viewing angle. From this perspective, the smaller the angle, the better, preferably 10° or less, and more preferably 5° or less.

[0088] Typically, the variation in the orientation of the P wave of the irradiated light at each position in the projection image display member is small, and the orientation of the polarization axis at each position generally varies. One method for suppressing the variation in the polarization axis and producing the projection image display member of the above-mentioned embodiment is to use a laminate film with a controlled orientation angle as the light-reflecting material of the projection image display member. More specifically, when producing the above-mentioned laminate film, it is effective to design the ratio of the longitudinal stretching to the widthwise stretching, the widthwise stretching speed, and the small stretching ratio in the heat treatment step to be favorable conditions for the above-mentioned production method. It is also effective to use an amorphous thermoplastic resin as the main component of the thermoplastic resin layer (layer B) that does not include the outermost layer among the thermoplastic resin layers constituting the alternating laminate structure of the laminate film.

[0089] The head-up display, manned transportation, and screen of the present invention will be described below. The head-up display of the present invention uses the transparent display system of the present invention. A head-up display is an image display device that enables a driver to simultaneously view the scenery outside the vehicle window while superimposing speed displays, navigation information, and the like. The transparent display system of the present invention is a transparent display system that combines image display capabilities and good appearance, and therefore can be suitably used for head-up displays that require such characteristics.

[0090] The manned transportation of the present invention is equipped with the transparent display system of the present invention or the head-up display of the present invention. Manned transportation refers to transportation means, such as vehicles, trains, airplanes, and ships, that are driven by humans or that operate unmanned with passengers. In such manned transportation, the driver is required to simultaneously view the scenery outside the vehicle window while superimposing speed displays, navigation information, and the like, and therefore it is preferable that the manned transportation be equipped with a transparent display system that combines image display capability and visual appeal, or a head-up display using such a transparent display system.

[0091] The screen of the present invention is made using the transparent display system of the present invention. Here, the screen is a system that combines a curtain for projecting and viewing an image with an image projector. The screen of the present invention has excellent image display properties and appearance, and can be used for spatial presentation in amusement applications, signage, show windows, and other electronic signage applications. [Example]

[0092] The transparent display system of the present invention and the laminate film used as a light-reflecting material thereof will be described below using examples. However, the transparent display system of the present invention and the laminate film used as a light-reflecting material thereof are not limited to the following embodiments.

[0093] [Methods for measuring physical properties and evaluating effects] The methods for evaluating the physical properties and the effects are as follows.

[0094] (1) Polarization axis, Rmax(60), Rmin(60), 60° transmittance Measurement was carried out according to the following procedures (A), (B), and (C). (A) Using a phase difference measurement device (KOBRA-21ADH) manufactured by Oji Scientific Instruments, the in-plane orientation axis direction of the light-reflecting material at an incident angle of 0° was measured. Next, a Hitachi spectrophotometer (U-4100 Spectrophotometer) was fitted with an attached variable-angle reflection unit and a Glan-Taylor polarizer. The orientation axis direction of the projection image display component was set at an azimuth angle of 0°, and the film was rotated clockwise from 0° to 10° in 1° increments and counterclockwise from 1° to 10° in 1° increments. The reflectance of P waves in the wavelength range of 400 to 700 nm at an incident angle θ = 60° was measured in 1 nm increments from each azimuth angle relative to the normal to the film surface. The azimuth angle direction that maximized the average reflectance of P waves in the wavelength range of 400 to 700 nm at an incident angle of 60° for each azimuth angle was determined as the polarization axis. (B) A Hitachi spectrophotometer (U-4100 Spectrophotometer) was fitted with an attached variable-angle reflector and Glan-Taylor polarizer. The light-entering surface of the projection image display component was the reflecting surface, and the polarization axis identified in (A) was the incident direction. The reflectance of P waves was measured at an incident angle of 60° in 1-nm increments. From the resulting reflectance spectrum, the average reflectance from 400 to 700 nm was calculated and designated Rmax(60). Similarly, the reflectance of P waves was measured at an incident angle of 60° in 1-nm increments, with the incident surface oriented 90° to the polarization axis. From the resulting reflectance spectrum, the average reflectance from 400 to 700 nm was calculated and designated Rmin(60). The measurement conditions were: slit: 2 nm (visible) / automatic control (infrared), gain: 2, and scan speed: 600 nm / min (the same applies to R(12) described below). (C) The 60° transmittance of the projection image display component was measured in the same manner as (B), except that only the attached angle-variable reflection unit was attached to a Hitachi spectrophotometer (U-4100 Spectrophotometer), the incident light was unpolarized, and the transmittance was measured.

[0095] (2)R(12) A Hitachi spectrophotometer (U-4100 Spectrophotometer) was fitted with a 12° specular reflection accessory (P / N 134-0104), and light was incident on the projection image display element at an incident angle of 12°. The reflectance (absolute reflectance) was measured at wavelengths of 400 to 700 nm at 1 nm intervals. The average of the obtained values was calculated and designated as R(12).

[0096] (3) Retardation (phase difference) Measurement was performed using a phase difference measuring device (KOBRA-21ADH) manufactured by Oji Scientific Instruments Co., Ltd. A 3.5 cm x 3.5 cm piece was cut out from the projection image display member and placed in the device, and the retardation at a wavelength of 590 nm at an incident angle of 0° was measured.

[0097] (4) Total Haze The total haze of the projection image display member was measured using a haze meter (HGM-2DP) manufactured by Suga Test Instruments Co., Ltd. The measurement was repeated 10 times at randomly changed measurement positions, and the average value was taken as the total haze value of the projection image display member.

[0098] (5) Arithmetic mean roughness Measurement was carried out according to the following procedures (A) to (C). (A) A projection image display member was cut into a size of 6 cm x 6 cm and measured using a scanning white light interference microscope (device: "VertScan" (registered trademark) VS1540 manufactured by Hitachi High-Tech Science Corporation). When the measurement sample was a projection image display member, a 50x objective lens was used, the measurement mode was set to WAVE mode, the measurement area was 113 μm x 113 μm, and the measurement Y axis was set to any one direction of the measurement sample, and the light incident surface of the projection image display member or light-reflecting material was measured over 90 fields of view. (B) The obtained microscope image was subjected to image processing using the surface analysis software VS-Viewer Version 10.0.3.0 built into the microscope under the following image processing conditions. (Image processing conditions) Interpolation process: Full interpolation Filtering: Median (3x3 pixels) Surface correction: 4th order (C) For each measurement image processed under the above image processing conditions, the following analysis conditions were selected along with "Height Parameters" in the ISO parameter analysis within the surface analysis software, and the arithmetic mean height Sa obtained by outputting the resulting set of values into the parameter sheet was used as the arithmetic mean roughness of the measurement surface. Note that the arithmetic mean roughness was calculated for 80 fields of view, excluding the five fields above and below each field of view, and the average value obtained was used.

[0099] (6) Crack generation pressure The micro-scratch test was carried out in accordance with JIS R-3255: 1997. Specifically, a 4 cm x 4 cm square projection image display member was prepared and placed on the measurement stage of a scratch tester (CSR5000 manufactured by Rhesca Co.) with the light incident surface facing the stylus, and a surface scratch test was carried out under the following conditions. Stylus: Diamond stylus (stylus diameter 15 μm) Scratch speed: 10 μm / sec Excitation amplitude: 50μm Excitation frequency: 45Hz Touch detection level: 3.0mN Load condition: Monotonically increasing (+1.33mN / sec) Initial load: 0mN Maximum load: 100mN Measurement time: 600 seconds Measurement environment: 25°C, relative humidity 65% The load at which the vertical sensor acceleration value (unitless) exceeded 200 for the first time during the time-dependent change from the start of measurement was defined as the crack initiation load. If the acceleration did not exceed 200 during the second measurement, the crack initiation pressure was defined as 800 mN. The crack initiation pressure was calculated from the obtained load and stylus diameter using Equation 1. Equation 1: Crack initiation pressure (GPa) = Crack initiation load (mN) ÷ (15 ÷ 2) 2 ÷π×1000.

[0100] (7) Number of layers and thickness of laminated film, thickness of surface layer The cross section of the sample cut perpendicular to the film surface using a microtome was observed using a transmission electron microscope (TEM) to confirm the number of layers in the laminated film, the thickness of each layer forming the laminate structure, and the thickness of the surface layer. The cross-sectional photographs were taken using a transmission electron microscope H-7100FA (manufactured by Hitachi, Ltd.) at an accelerating voltage of 75 kV. The thickness of the surface layer was measured using the microscope's length measurement function.

[0101] (8) Refractive index of the outermost layer of the light incident surface of the projection image display member, including the outermost surface of the laminated film (Layer A) The refractive index of the light incident surface of the projection image display member and the outermost surface of the laminate film were measured using a Cylon Technology SPA-400 prism coupler. The laser wavelength used for the measurement was 633 nm. The in-plane refractive index was determined by averaging the values measured for both outermost layers in the direction of the orientation axis and in the direction perpendicular to the orientation axis. The thickness refractive index was determined by averaging the values measured from the orientation axis side and the direction perpendicular to the orientation axis side for both outermost layers. If the in-plane refractive index is 1.52 or higher, it is considered to be the refractive index of the layer (layer A) containing the outermost surface of the alternating laminated portion of the laminate film. If the refractive index is less than 1.52, it can be considered to be the refractive index of a low refractive index layer or protective layer.

[0102] (9) Refractive index of layer B of laminated film Using the thickness of each layer of the laminate film calculated in (7) and the refractive index of the thermoplastic resin layer (Layer A) constituting the outermost surface, and setting the refractive index of each layer other than the outermost layer to an arbitrary value, an optical simulation of the VBA program reflectance was performed using the characteristic matrix method of the optical thin film (Mitsunobu Kohiyama (2006). Optical Thin Film Filter Design, Optronics Co., Ltd.). Next, from the optical simulation results and the reflectance measured by the measurement method described below, the average reflectance of the reflection band that is 10% or more continuously over 100 nm or more in the wavelength range of 400 to 2000 nm was calculated. If the difference between the two was ±2% or less, that refractive index was taken as the refractive index of the layer other than the outermost layer (Layer B).

[0103] (10) Fabrication of projection image display components A 9 cm x 9 cm laminated film was manually attached to a 10 cm square glass sheet at room temperature using a roller and optical adhesive TD-06A manufactured by Tomoegawa Paper Co., Ltd. to obtain a projection image display member.

[0104] (11) Abrasion resistance test A test cloth was pressed against the light incident surface of the projection image display member prepared in (10), and rubbed under the following rubbing conditions. The occurrence of scratches was observed after a specified number of reciprocating strokes, and the number of times at which one or more scratches occurred was determined. The minimum pass mark was no scratches after 1,000 strokes, and the more tests before scratches occurred, the better the abrasion resistance. <Rubbing conditions> Test cloth: TRIBOTOUCH TT-STex (wool) Travel amount: 20mm Traveling speed: 50mm / sec Pressing area: 6.5mm x 6.5mm Stress: 74kPa Observe the occurrence of scratches: every 100 strokes up to 1000 strokes, every 1000 strokes from 1000 to 30000 strokes, and every 5000 strokes after 30000 strokes.

[0105] (12) Heat processing test The projection image display member prepared in (10) was left standing at 150°C for 2 hours, and after cooling to room temperature, the appearance was inspected and the number of cracks in the outermost layer was counted. The evaluation criteria were as follows: ○: 0 △: 1 to 3 ×: 4 or more.

[0106] (13) Scenery visibility through the projected image display component A projection image display element was prepared in the same manner as in (10), except that the laminated film was 29 cm x 29 cm and the glass was 30 cm square. The element was tilted at an angle of 60° from the vertical direction, and the visibility was evaluated when the outside scenery was viewed visually through the projection image display element. The evaluation criteria are as follows: ◎: The outside scenery was clearly visible. ○: Although the clarity was poor, the outside scenery could be seen without any problems. △: The outside scenery was visible to some extent. ×: The outside view was not visible.

[0107] (14) Low visibility A projection image display element was prepared in the same manner as in (10), except that the laminated film was 29 cm x 29 cm and the glass was 30 cm square. The element was tilted at an angle of 60° from the vertical, and the conspicuousness of the laminated film in the glass was evaluated when the glass laminated sample was viewed from the front, simulating the view from the driver's seat, and from an angle (45°), simulating the view from the passenger seat. The evaluation criteria are as follows: ⊚: The laminated film in the glass was not noticeable and not bothersome. ◯: The laminated film in the glass was slightly noticeable but not bothersome. △: The laminated film in the glass was slightly noticeable, but the annoyance was at an acceptable level. ×: The laminated film in the glass was very noticeable.

[0108] (15) Head-up display (HUD) visibility A HUD system was fabricated using the projection image display member fabricated in (10) and an Apple iPad (registered trademark) 2 that generates and emits P waves as a projection light source, and the information display performance was evaluated visually when an image was projected at an incident angle of 60°. The evaluation criteria were as follows: ⊚: The image projected onto the projection image display member was very clearly visible. ◯: The image projected onto the projection image display member was clearly visible. Δ: The image projected onto the projection image display member was less clear, but slightly visible. ×: The displayed image was less clear than the standard of "△", or the image itself was impossible to display.

[0109] (16) Uneven display in projected image display components The HUD display performance of the entire image display element when an image was projected using the method in (15) was evaluated visually. The evaluation criteria were as follows: ◎: The image was displayed clearly and evenly across the entire screen. ○: The image was slightly blurred in some areas, but was displayed clearly over a wide area. △: The image was blurred in some areas, but was at an acceptable level. ×: Unacceptable image display defects were observed.

[0110] [Resins used to obtain laminated film] To obtain the laminated films of each Example and Comparative Example, the resins shown in Table 1 and the hard coat paints shown in Table 2 were used. "mol %" indicates the proportion of the dicarboxylic acid unit and the diol unit, respectively, with the total amount taken as 100 mol %.

[0111] [Laminated film A] Thermoplastic resin A was polyethylene terephthalate (resin 1). Thermoplastic resin B was a polyethylene terephthalate copolymer (polyethylene terephthalate copolymerized with 80 mol% terephthalic acid and 20 mol% 2,6-naphthalenedicarboxylic acid) (resin 2). The prepared thermoplastic resins A and B were fed into two single-screw extruders and melted at 280°C. Next, thermoplastic resins A and B were each passed through five FSS-type leaf disc filters. Then, while being metered by a gear pump, they were merged in a lamination device with 801 slits so that the mass ratio of thermoplastic resin A to thermoplastic resin B (A / B) was 1. This resulted in a molten resin laminate consisting of 801 layers laminated alternately in the thickness direction, with thermoplastic resin A positioned as the outermost layer on both sides. The molten resin laminate was then extruded from a die and cooled and solidified on a casting drum at 25°C and a speed of 4 m / min to obtain a cast film. The resulting cast film was heated using a group of rolls set at 60°C, then stretched 3.1 times in the longitudinal direction at a stretching rate of 50% / sec using rolls set at 87°C, and then cooled. The resulting uniaxially stretched film was introduced into a tenter, preheated with hot air at 90°C, and then stretched 3.6 times in the width direction at a stretching rate of 5% / sec at 95°C. The stretched film was then heat-treated in the tenter with hot air at 210°C, followed by a 3% relaxation treatment (Rx) in the width direction under the same temperature conditions, and then cooled to room temperature. Thus, a laminated film A with a thickness of 80 μm and a width of 1.0 m was obtained.

[0112] [Laminated Films B-Q] The laminate film was produced in the same manner as laminate film A, except that the number of layers, the resin of each layer, and the film-forming conditions were as shown in Table 1. The evaluation results are shown in Table 1.

[0113] [Table 1]

[0114] Example 1 The resulting laminated film A was cut to the size of the projection image display element used for each evaluation, with the center positioned 25 cm from the widthwise edge of the laminated film A. A protective layer was then laminated using the following procedure. 67 parts by mass of Momentive Material Performance Hardcoat UVHC7400 and 33 parts by mass of Nippon Shokubai Nanoparticles (silica particles (average particle diameter: 20 nm)) IX-3-TR-M-02-J were mixed to obtain a protective layer coating (HC-1). (The mixing ratio here refers to the ratio of the entire composition, including the solvent.) HC-1 was applied to one side of the laminated film A using a #12 stainless steel coating wire bar from RD Specialties, and the film was then placed in a high-temperature chamber at 100°C to evaporate the solvent. Next, a UV irradiation device (Eye Graphics ECS-401GX) was used to apply an integrated light dose of 770 mJ / cm. 2 The HC-1 was cured by irradiating it with UV light so that the protective layer was on the outermost surface, forming a protective layer with a total thickness of 10 μm. A projection image display member was then fabricated using the method described in "(10) Fabrication of Projection Image Display Members" so that the protective layer was on the outermost surface, and a head-up display (HUD) was fabricated using the method described in "(12) Head-up Display (HUD) Display Performance." The evaluation results for the projection image display member and HUD are shown in Table 3-1.

[0115] (Examples 2 to 18, Comparative Examples 1 to 3) A projection image display member and HUD were produced in the same manner as in Example 1, except that the type of laminate film and the coating used to form the protective layer were as shown in Tables 2-1, 2-2, 3-1, and 3-2. The evaluation results are shown in Tables 3-1 and 3-2. The types of coating raw materials used to form the protective layer, as well as the concentrations of particles and solids, are shown in Table 2-1, and the mixing ratios are shown in Table 2-2. For Example 18, which did not have a protective layer, the step of providing a protective layer was not carried out.

[0116] Example 19 A 0.103 μm thick SiO layer was laminated on the resulting laminated film G using the following procedure. The sputtering equipment used was a single-wafer sputtering equipment UB-1 manufactured by ULVAC Corporation, and the conditions were Ar discharge gas, pressure 1.2 Pa, substrate temperature room temperature, RF output 500 W, and deposition time 40 seconds. A projection image display member and HUD were then fabricated in the same manner as in Example 1. The evaluation results are shown in Table 3-2.

[0117] Examples 20 to 23 A projection image display member and a HUD were fabricated in the same manner as in Example 19, except that the layer to be laminated was an MgF2 layer and the layer thickness was as shown in Table 3-2. The evaluation results are shown in Table 3-2. The layer thickness was adjusted by the film formation time.

[0118] [Table 2-1]

[0119] [Table 2-2]

[0120] [Table 2-3]

[0121] [Table 3-1]

[0122] In the table, the laminated film corresponds to Table 1, and the coating material for forming the protective layer / low refractive index layer corresponds to those shown in Tables 2-1 to 2-3 (the same applies to Table 3-2).

[0123] [Table 3-2]

[0124] In the table, "100x" in the abrasion resistance test means that scratches occurred after 100 cycles. [Industrial Applicability]

[0125] The present invention provides a transparent display system that combines image display capability and visual appeal. Because of these excellent characteristics, the transparent display system of the present invention can be used in a variety of applications, including head-up displays for manned transportation, amusement facilities as a transparent screen for spatial presentation, and electronic signage such as signage and show windows. [Explanation of symbols]

[0126] 1: Image projector 2: Light of the image 3: Projection image display component 4:Landscape 5: Observer 6: Angle of incidence of light in the image 7: Light-reflecting material (laminated film) 8: Adhesive layer 9: Transparent hard material 10: Point C 11:X1 point 12:X2 points 13: Y1 point 14: Y2 points

Claims

1. A transparent display system comprising: an image projector that projects an image by irradiating light; and a projection image display member onto which an image is projected by the light from the image projector, the difference between the average reflectance R(12) at wavelengths of 400 nm to 700 nm when light is incident on the projection image display member so that the angle between the light and the normal to the image display surface is 12° and the average reflectance Rmax(60) at wavelengths of 400 nm to 700 nm when P waves are incident on the projection image display member so that the angle between the light and the polarization axis, which is the orientation at which the reflectance of P waves is maximum, is 5% or more; and a difference of 5% or more between the Rmax(60) and the average reflectance Rmin(60) of wavelengths of 400 nm to 700 nm when P waves are incident on the projection image display member so that the angle between the Rmax(60) and the direction orthogonal to the polarization axis is 60°.

2. 10. The transparent display system of claim 1, wherein R(12) is 30% or less.

3. 3. The transparent display system of claim 1, wherein the Rmax(60) is 20% or greater.

4. 3. The transparent display system according to claim 1, wherein the angle between the polarization axis and the direction in which the P wave of the light emitted from the image projector is maximum is between 0° and 20°.

5. 3. The transparent display system of claim 1, wherein the retardation of the projection image display member is greater than 2000 nm.

6. 3. The transparent display system of claim 1, wherein the projection image display member has a structure in which a transparent hard material and a light-reflecting material are laminated together via an adhesive layer in at least a portion thereof, and the light-reflecting material is positioned on the light incident surface of the projection image display member.

7. 10. The transparent display system of claim 1, wherein the projection image display member has a total haze of 1.0% or less.

8. The transparent display system according to claim 1 , further comprising a protective layer on the outermost surface of the projection image display member.

9. 3. The transparent display system according to claim 1, wherein the arithmetic mean roughness of the light incident surface of the projection image display member is 0.90 nm or less.

10. 3. The transparent display system according to claim 1, wherein the crack generation pressure measured on the light incident surface of the projection image display member by a micro scratch test method in accordance with JIS R-3255:1997 is 100 GPa or more and 600 GPa or less.

11. 3. The transparent display system according to claim 1, wherein at least one low refractive index layer having a refractive index of 1.50 or less is present on the light incident surface side of the projection image display member.

12. The transparent display system according to claim 11 , wherein the product n×d of the refractive index n and the layer thickness d of the low refractive index layer is 150 nm or more and 250 nm or less.

13. 3. The transparent display system of claim 1, wherein the difference between the maximum and minimum retardation values at point C, point X1, point X2, point Y1, and point Y2 is 1000 nm or less, when the center point of the projection image display member is point C, the midpoint between point C and the upper end is point X1, the midpoint between point C and the lower end is point X2, the midpoint between point C and the left end is point Y1, and the midpoint between point C and the right end is point Y2.

14. 3. The transparent display system according to claim 1, wherein, when the center point of the projection image display member is defined as point C, the midpoint between point C and the upper end is defined as point X1, the midpoint between point C and the lower end is defined as point X2, the midpoint between point C and the left end is defined as point Y1, and the midpoint between point C and the right end is defined as point Y2, the angles formed between each polarization axis and the direction in which the P wave of the light irradiated from the image projector is maximum at points C, X1, X2, Y1, and Y2 are between 0° and 20°.

15. 7. The transparent display system according to claim 6, wherein the light-reflecting material is a laminated film in which at least two types of thermoplastic resin layers are laminated to form 51 or more layers.

16. A head-up display using the transparent display system according to claim 1 or 2.

17. A manned transportation vehicle equipped with the transparent display system according to claim 1 or 2 or the head-up display according to claim 17.

18. A screen comprising the transparent display system according to claim 1 or 2.

Images