Head-up display system and transport aircraft having the same

Abstract

To provide a HUD system capable of displaying driving assistance information on display planes with different focal lengths using a simpler HUD device configuration.SOLUTION: A head-up display system 1 is provided, comprising: a projector 10 including a light source 30 for emitting image projection light, and an intermediate image screen 14 having a first rugged portion 141 for forming a real image from the image projection light and a first flat portion 142 for transmitting the image projection light; and a windshield glass 26 having a second rugged portion 262 for forming a real image from the projection light transmitting through the first flat portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a head-up display system and a transport aircraft having the same. [Background technology]

[0002] A so-called head-up display (hereinafter referred to as HUD) is known that projects an image onto the windshield glass of a vehicle or the like and provides driving assistance information such as route guidance, driving speed, and warnings to a vehicle user (observer) such as a driver through the windshield glass. HUD allows the viewer to view the external world ahead and obtain various driving assistance information, such as route guidance, driving speed, and vehicle status, without significantly shifting their line of sight or focus, enabling safer, more stress-free driving. The basic structure of a HUD is generally as follows: First, light projected from a projector built into the dashboard is focused as an intermediate image on the surface of an intermediate image screen (diffuser plate). This intermediate image is magnified by a concave mirror (magnifying glass), passes through a transparent window in the dashboard, and is reflected by the windshield glass, which has a built-in half mirror, before being directed to the observer. The observer perceives this intermediate image as a so-called virtual image located in front of the windshield glass. In other words, the observer perceives the driving assistance information as if it were floating above the road.

[0003] In recent years, a technology has been proposed that displays two virtual image planes with different focal lengths in parallel on the windshield glass (see, for example, Non-Patent Document 1). In a HUD that employs such technology, route guidance, warnings, and other information that the observer should grasp in real time according to the driving situation are displayed on the virtual image plane farther from the observer, and information such as driving speed is displayed on the virtual image plane closer to the observer. [Prior art documents] [Patent documents]

[0004] [Non-Patent Document 1] Journal of the Institute of Image Information and Television Engineers, 2018, Vol. 72, No. 10, pp. J142-J147 Summary of the Invention [Problem to be solved by the invention]

[0005] The technology described in Non-Patent Document 1 supports the user's driving by displaying both a display image close to the observer and a display image far from the observer on a virtual image surface. However, because two different virtual image surfaces are displayed in parallel on the windshield glass, the configuration of the HUD system becomes complicated.

[0006] An object of the present invention is to provide a HUD system that is capable of displaying different driving assistance information on display surfaces with different focal lengths using a simpler HUD device configuration. [Means for solving the problem]

[0007] The above-mentioned object of the present invention is achieved by the following means. [1] a light source that emits projection light; an intermediate image screen having a first uneven portion that converts the projected light into a real image and a first smooth portion through which the projected light passes; a projector having; a windshield glass having a second uneven portion that converts projected light passing through the first smooth portion into an actual image; A head-up display system comprising: [2] The head-up display system according to [1], wherein the windshield glass has a second smooth portion that reflects the projected light that has been imaged by the first uneven portion toward the observer. [3] The head-up display system according to [2], wherein the second smooth portion has a selective reflection layer or a dielectric multilayer film. [4] The head-up display system according to any one of [1] to [3], wherein the second concave-convex portion has black ceramics as the convex portions. [5] The head-up display system according to [4], wherein the second uneven portion has a reflective film that reflects the real image formed by the second uneven portion toward the observer. [6] The head-up display system according to any one of [1] to [3], wherein the second concave-convex portion is a screen film. [7] The head-up display system according to any one of [1] to [6], wherein the convex portions of the first concave-convex portion have a height of 0.3 μm or more and a width of 1.0 μm or more. [8] The head-up display system according to any one of [1] to [7], wherein the convex portions of the second concave-convex portion have a height of 0.3 μm or more and a width of 1.0 μm or more. [9] The head-up display system according to any one of [1] to [8], wherein the light source is a laser light source.

[10] A transport aircraft equipped with the head-up display system according to any one of [1] to [9]. [Effects of the Invention]

[0008] The HUD system of the present invention makes it possible to display different driving assistance information on display surfaces with different focal lengths using a simpler HUD device configuration. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an example of a head-up display system according to the present invention. [Figure 2] 1 is a plan view showing an example of the configuration of an intermediate image screen of the present invention. FIG. [Figure 3] 1 is a schematic diagram showing an example of the configuration of a windshield glass according to an embodiment of the present invention. [Figure 4]1 is a schematic diagram showing an example of the configuration of a windshield glass according to an embodiment of the present invention. [Figure 5] 1 is a schematic diagram showing an example of the configuration of a windshield glass according to an embodiment of the present invention. [Figure 6] 1 is a schematic diagram showing an example of the configuration of a windshield glass according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a head-up display system (hereinafter referred to as HUD system) of the present invention will be described in detail based on preferred embodiments illustrated in the accompanying drawings. Note that the dimensions and scale of each part in the drawings may differ from the actual dimensions for the sake of convenience of explanation. Also, the drawings may be shown schematically to facilitate understanding.

[0011] In this specification, the symbol "to" is used to mean that the numerical values ​​before and after it are included as the lower and upper limits. For example, when ε1 is a value between α1 and β1, the range of ε1 includes the numerical values ​​α1 and β1, and expressed in mathematical notation, α1≦ε1≦β1. In this specification, unless otherwise specified, the "angles" expressed by specific numerical values ​​and the terms "parallel" and "perpendicular" include error ranges generally accepted in the technical field of the present invention.

[0012] In this specification, unless otherwise specified, the term "light" refers to visible light and natural light (unpolarized). Visible light is electromagnetic radiation with wavelengths visible to the human eye, in the wavelength range of 380 to 780 nm. Invisible light is light with wavelengths shorter than 380 nm or longer than 780 nm. In addition, although not limited thereto, light in the visible light wavelength range of 420 nm to 490 nm is blue light (B light), light in the wavelength range of 495 nm to 570 nm is green light (G light), and light in the wavelength range of 620 nm to 750 nm is red light (R light). Furthermore, although not limited thereto, infrared light refers to the invisible light wavelength range of 780 nm to 2000 nm.

[0013] In this specification, p-polarized light refers to polarized light that vibrates in a direction parallel to the plane of incidence of light. The plane of incidence refers to a plane that is perpendicular to a reflective surface (such as a windshield glass surface) and contains both the incident and reflected light rays. In p-polarized light, the vibration plane of the electric field vector is parallel to the plane of incidence.

[0014] In this specification, the in-plane phase difference (in-plane retardation Re) is a value measured using an AxoScan manufactured by Axometrics, Inc. Unless otherwise specified, the measurement wavelength is 550 nm.

[0015] In this specification, the term "projection image" refers to an image based on the projection of light from a projector. In the HUD system of the present invention, the projected image is visually recognized by the observer as a virtual image that appears to float beyond the smooth portion of the windshield glass. In this specification, the term "screen image" refers to an image displayed on the uneven surface of the windshield glass or an image made real by an intermediate image screen. A screen image is a real image, whereas a projected image is a virtual image. The images and projected video may be monochrome images, multicolor images with two or more colors, or full-color images.

[0016] In this specification, the "visible light transmittance" refers to the visible light transmittance for an A light source as defined in JIS (Japanese Industrial Standards) R 3212:2015 (Testing methods for automotive safety glass). That is, it is the transmittance obtained by measuring the transmittance at each wavelength in the range of 380 to 780 nm using a spectrophotometer with Illuminant A, and then multiplying the transmittance at each wavelength by a weighting coefficient obtained from the wavelength distribution and wavelength interval of the CIE (Commission Internationale de l'Eclairage) standard relative luminosity factor for light adaptation and calculating the weighted average. When simply referring to "reflected light" or "transmitted light," it is used to mean scattered light and diffracted light as well.

[0017] In this specification, the term "liquid crystal compound" is used to include compounds that no longer exhibit liquid crystallinity due to a curing reaction or the like.

[0018] The HUD system of the present invention is typically mounted on and used in vehicles such as automobiles and trains, aircraft, and transport vehicles such as ships.

[0019] FIG. 1 conceptually shows an example of a HUD system according to the present invention. The HUD system 1 of the present invention shown in FIG. 1 includes a HUD projector 10 and a windshield glass 26.

[0020] 1 includes an image forming unit 12, an intermediate image screen 14, a reflecting member 16, and a concave mirror 18. In the following description, the HUD projector 10 will be simply referred to as the "projector."

[0021] In the HUD system 1 illustrated in FIG. 1, the projection light projected by the projector 10 passes through a transparent window 24 provided in the dashboard 20 and a retardation plate 25 provided in the transparent window 24, and is projected onto the smooth and uneven portions of the windshield glass 26, and is observed by an observer 0. As with a normal HUD system, in the example illustrated in FIG. 1, observer 0 observes the image projected onto the smooth portion of the windshield glass 26 as a virtual image through the windshield glass 26, and the image projected onto the uneven portion as a real image.

[0022] It should be noted that the head-up display using the projector 10 of the present invention is not limited to a head-up display (windshield head-up display) that projects an image onto the windshield glass 26, as exemplified in Fig. 1. In other words, the head-up display using the projector 10 of the present invention can be any of a variety of known head-up displays that project an image onto various components, such as a head-up display that projects an image onto a so-called combiner (combiner head-up display).

[0023] In the projector 10 illustrated in FIG. 1, the image forming section 12 includes a light source 30, a mirror 32, a polarizing plate 34, and an optical deflector 36. The image forming unit 12 is a so-called light beam scanner that forms an image by scanning a light beam.

[0024] The image forming unit 12 emits three light beams modulated according to the projection image from a light source 30, combines these three light beams using a mirror 32, converts them into p-polarized light using a polarizing plate 34, and then performs secondary scanning using an optical deflector 36. The projector 10 secondarily scans the light beam modulated according to the projection image using the optical deflector 36, converting the light beam into a real image using the uneven portion 141 (first uneven portion) of the intermediate image screen 14, and reflects this real image along a predetermined optical path using the reflecting member 16 and the concave mirror 18. As described above, this reflected light passes through the transparent window 24 and the retardation plate 25 provided in the dashboard 20, and is projected onto the smooth portion 261 (second smooth portion) of the windshield glass 26, and is observed as a virtual image by the viewer 0 through the windshield glass 26. Furthermore, the projector 10 secondarily scans the light beam modulated according to the projection image using the optical deflector 36, transmits the light beam through the smooth portion 142 (first smooth portion) of the intermediate image screen 14, and reflects it along a predetermined optical path by the reflecting member 16 and the concave mirror 18. This reflected light passes through the transmission window 24 and the retardation plate 25 provided in the dashboard 20, and is converted into a real image by the uneven portion 262 (second uneven portion) of the windshield glass 26, which is observed as a real image on the windshield glass 26 by the observer 0. Details of the uneven portion 262 and the smooth portion 261 of the windshield glass 26 and the uneven portion 141 and the smooth portion 142 of the intermediate image screen 14 will be described later. The arrangement of the uneven portion 262 is not limited to the arrangement exemplified in FIG. 1 as long as it can form a real image.

[0025] The image forming unit 12 has, as light sources 30, an R light source 30R that emits a red light beam, a G light source 30G that emits a green light beam, and a B light source 30B that emits a blue light beam. There are no particular limitations on the light sources 30 (R light source 30R, G light source 30G, and B light source 30B) as long as they emit light in the desired wavelength range, and various light sources used for image formation by scanning a light beam can be used. Examples of the light source 30 include an LED (Light Emitting Diode), a discharge tube, and a laser light source. Note that the LED includes a light emitting diode and an organic light emitting diode (OLED).

[0026] There is no limitation on the half-value width of the light emitted from the light source 30 (emitted light), but it is preferable that it is narrow to some extent. The half width (full width at half maximum) of the light emitted from the light source 30 is preferably 20 nm or less, more preferably 15 nm or less, further preferably 10 nm or less, and particularly preferably 7 nm or less. By setting the half-width of the light emitted from the light source 30 to 20 nm or less, a selective reflection layer with a narrow selective reflection range (half-width of reflection) can be used in the reflecting member 16 described below. This makes it possible to preferably prevent deterioration of the components of the projector 10 due to intrusion of sunlight. It also makes it possible to prevent a decrease in the reflectance of the reflecting member due to wavelength fluctuations in the light emitted from the light source 30. Furthermore, it is possible to further improve the image quality of the virtual image projected on the windshield glass 26. Note that, from the viewpoint of making the projected light brighter and the virtual image projected on the windshield glass 26 brighter, it is also preferable that the half-width of the light emitted from the light source 30 be 5 nm or less.

[0027] The half-width of the light emitted from light source 30 can be determined using a spectrophotometer or the like. Specifically, the half-width is the value obtained by subtracting the wavelength on the short wavelength side from the wavelength on the long wavelength side that provides 50% of the maximum brightness (maximum value) of the emitted light. The half-width can be determined by projecting the emitted light onto a white board and measuring the reflected light with a spectrophotometer. Furthermore, if the light source 30 is a commercially available product, the catalog value may be used as the half-width.

[0028] The R light source 30R, G light source 30G, and B light source 30B are modulated and driven by normal control means and driving means (not shown) in accordance with the image to be projected. Note that instead of directly modulating the light source 30, a normal optical modulator may be used to modulate the light beam emitted by the light source 30 in accordance with the projected image. The modulation can be performed by a conventional method such as intensity modulation or pulse modulation.

[0029] It should be noted that the image forming unit 12 illustrated in FIG. 1 corresponds to a full-color projection image that reflects red light, green light, and blue light, but the present invention is not limited to this. That is, in the present invention, the light source 30 may be one that corresponds to a two-color projection image, having only the R light source 30R and the G light source 30G, or having only the R light source 30R and the B light source 30B, or having only the G light source 30G and the B light source 30B. Also, the light source 30 may be one of the R light source 30R, the G light source 30G, and the B light source 30B. This also applies to the mirror 32 described later.

[0030] In the embodiment shown in FIG. 1, the image forming unit 12 includes, as mirrors 32, an R mirror 32R that reflects light emitted from an R light source 30R, a G mirror 32G that reflects light emitted from a G light source 30G, and a B mirror 32B that reflects light emitted from a B light source 30B. The R mirror 32R is a normal light-reflecting mirror used in optical devices. The G mirror 32G and the B mirror 32B are normal dichroic mirrors. The G mirror 32G reflects green light and transmits light in other wavelength ranges. The B mirror 32B reflects blue light and transmits light in other wavelength ranges.

[0031] In the image forming unit 12, the red light beam emitted by the R light source 30R is reflected by the R mirror 32R and passes through the G mirror 32G and the B mirror 32B. The green light beam emitted by the G light source 30G is reflected by the G mirror 32G and passes through the B mirror 32B. The blue light beam emitted by the B light source 30B is reflected by the B mirror 32B. As a result, the three light beams of red, green and blue are combined into one light beam, which is incident on the polarizing plate .

[0032] The polarizing plate 34 converts the incident light beam into p-polarized light (p-linearly polarized light). There are no limitations on the polarizing plate 34, and various types of ordinary linear polarizing plates (linear polarizers) can be used. An example of the polarizing plate 34 is a polarizing plate formed by laminating thin films with different refractive index anisotropy. Examples of polarizing plates formed by laminating thin films with different refractive index anisotropy include those described in JP-A-9-506837. Specifically, polarizing plates can be formed using a wide variety of materials by processing them under conditions selected to obtain the desired refractive index relationship. Generally, one of the first materials must have a different refractive index in a selected direction than the second material. This refractive index difference can be achieved in a variety of ways, including stretching, extrusion, or coating during or after film formation. Furthermore, it is preferable for the two materials to have similar rheological properties so that they can be coextruded. Examples of rheological properties include melt viscosity.

[0033] The polarizing plate having thin films with different refractive anisotropies laminated thereon may be a commercially available product. Examples of commercially available products include DBEF (manufactured by 3M) and APF (Advanced Polarizing Film).

[0034] The polarizer 34 may be an absorptive polarizer containing an iodine compound, or a general linear polarizer such as a reflective polarizer such as a wire grid.

[0035] The light beam, which has been converted into p-polarized light by the polarizing plate 34 and modulated in accordance with the projection image or picture, is secondarily scanned by the optical deflector 36 . Various types of ordinary optical deflectors capable of scanning a light beam secondarily can be used as the optical deflector 36. Examples of the optical deflector 36 include a galvanometer mirror, a combination of a galvanometer mirror and a polygon mirror, and a microelectromechanical system (MEMS). Of these, MEMS is preferably used.

[0036] There are no limitations on the scanning method, and ordinary light beam scanning methods such as random scanning and raster scanning can be used, with raster scanning being particularly preferred.

[0037] In raster scanning, the light beam can be driven, for example, at a resonant frequency in the horizontal direction and a sawtooth wave in the vertical direction. Image formation (drawing) by light beam scanning does not require a projection lens, making it easy to miniaturize the device.

[0038] In the projector 10 exemplified in FIG. 1, the image forming unit 12 forms a projection video and an image by scanning a light beam, but the present invention is not limited to this. That is, in the projector of the present invention, various types of normal image forming means used in HUD projectors (imagers) can be used as the image forming means. Examples of image forming means include a fluorescent tube, an LCD (Liquid Crystal Display) using liquid crystal, and an LCOS (Liquid Crystal On Silicon). Alternatively, as another example of the image forming means, for example, an organic electroluminescence (organic EL) display or the like is adopted. Alternatively, as another example of the image forming means, DLP (Digital Light Processing) using DMD (Digital Micromirror Device) or the like is adopted. In the image forming means listed above, an image is projected onto an intermediate image screen 14 from a projection lens. When the image forming means is an LCD or LCOS, the light source in the present invention is a backlight unit. When the image forming means is a DLP, the light source in the present invention is a light source that irradiates light onto a DMD. Furthermore, when the image forming means is an organic EL display, the display itself is the light source in the present invention.

[0039] A part of the projection light emitted from the image forming unit 12 is then formed into a real image (visible image) by the uneven portion 141 of the intermediate image screen . The intermediate image screen 14 is a characteristic component of the HUD system 1 of the present invention. FIG. 2 is a plan view showing an example of the configuration of the intermediate image screen 14 according to the present invention. The intermediate image screen 14 has an uneven portion 141 and a smooth portion 142. The shape of the uneven portion 141 is not particularly limited as long as it can form a real image. The uneven structure for forming a real image is widely known. The uneven portion 141 is composed of multiple convex portions 141a (first convex portions) protruding in the height direction. As illustrated in FIG. 2, the multiple convex portions 141a can form, for example, a honeycomb structure in plan view. The height dimension of the convex portions 141a is preferably 0.3 μm or more, more preferably 1.0 μm or more, and even more preferably 2.0 μm or more. The width dimension is preferably 1.0 μm or more, more preferably 3.0 μm or more, and even more preferably 10.0 μm or more. The smooth portion 142 is a region of the intermediate image screen 14 where the plurality of convex portions 141a are not formed, and has a smooth surface. Various types of normal intermediate image screens that convert a projected image into a real image in a head-up display projector can be applied to the uneven portion 141 of the intermediate image screen 14.

[0040] For example, a scattering film, a microlens array, or a rear-projection screen may be used as the uneven portion 141 of the intermediate image screen 14. If the uneven portion 141 is made of a plastic material or has birefringence, the polarization plane and light intensity of polarized light incident on the uneven portion 141 will be disturbed, which will result in color unevenness and other issues occurring in the projected image. However, the use of the retardation plate 25 can reduce the problem of color unevenness.

[0041] It is preferable that the uneven portion 141 of the intermediate image screen 14 has a function of widening and transmitting the incident projection light, because this allows the projection image to be displayed in an enlarged scale. An example of such an intermediate image screen is an intermediate image screen configured with a microlens array. Microlens arrays used in HUDs are described in, for example, Japanese Patent Laid-Open Nos. 2012-226303, 2010-145745, and 2007-523369.

[0042] As described above, the projection light that has been converted into a real image by the uneven portion 141 of the intermediate image screen 14 is reflected along a predetermined optical path by the reflecting member 16 and the concave mirror 18, passes through the transparent window 24 and the retardation plate 25 provided in the dashboard 20, and is projected onto the smooth portion 261 of the windshield glass 26, and is observed as a virtual image by the observer 0 through the windshield glass 26 (see the dashed line). Furthermore, the projection light that has passed through the smooth portion 142 of the intermediate image screen 14 (projection light that has not been made into a real image by the intermediate image screen 14) is reflected along a predetermined optical path by the reflecting member 16 and the concave mirror 18, as described above, and passes through the transmission window 24 and the retardation plate 25 provided in the dashboard 20 to be projected onto the uneven portion 262 of the windshield glass 26. The projection light projected onto the uneven portion 262 is made into a real image by the uneven portion 262, and this real image is observed at the uneven portion 262 by the observer 0.

[0043] The concave mirror 18 is a normal concave mirror that enlarges and projects the projection light and is used in HUD projectors. Note that, although the projector 10 illustrated in Fig. 1 uses the reflecting member 16 and the concave mirror 18 as members that change the optical path of the projection light, the present invention is not limited to this. In other words, the projector of the present invention may not have a concave mirror 18 and may have only a reflective member 16 as a component for changing the optical path of the projected light, or may have one or more other light-reflecting elements in addition to the reflective member 16 and the concave mirror 18. As the light reflecting element, in addition to a concave mirror and a normal mirror, a free-form mirror, etc. can also be used. In other words, the projector of the present invention can be configured using various light reflecting elements as long as it has the reflective member of the present invention.

[0044] The reflecting member 16 of the present invention can also function as a cold mirror, reflecting visible light (red, green, and blue light) and transmitting infrared light.

[0045] In an in-vehicle head-up display, external light such as sunlight may pass through the windshield glass 26 and the transparent window 24 and enter the projector 10, then travel in the opposite direction along the optical path of the projection light indicated by the dashed dotted line, and enter the intermediate image screen 14, the optical deflector 36, and the polarizing plate 34. Such sunlight heats these components, causing deterioration of heat-sensitive components. Here, it is mainly the infrared rays contained in sunlight that heat these components. Therefore, the reflective member 16 functions as a cold mirror that reflects visible light and transmits infrared rays, and the infrared rays of sunlight that enter the projector 10 are transmitted through the reflective member 16. This prevents the infrared rays of sunlight from being incident on the intermediate image screen 14, the optical deflector 36, and the polarizing plate 34 and causing thermal damage to these components. Furthermore, by using a cholesteric liquid crystal layer as the selective reflection layer of the reflecting member 16, half of the visible light contained in sunlight is transmitted through the reflecting member 16, which more effectively prevents damage to the intermediate image screen 14, the optical deflector 36, and the polarizing plate 34 due to heat.

[0046] The windshield glass 26 is a characteristic component of the HUD system 1 of the present invention. The windshield glass 26 has a smooth portion 261 and an uneven portion 262. The shape of the uneven portion 262 is not particularly limited as long as it can form a real image. The uneven portion 262 includes, for example, a plurality of convex portions (second convex portions) not shown. The height dimension of these convex portions is, for example, 0.3 μm or more, and the width dimension is, for example, 1.0 μm or more. Specific embodiments of the windshield glass 26 of the present invention will be described below as examples.

[0047] [Example 1] FIG. 3 is a schematic diagram showing an example of the configuration of a windshield glass 26 according to Example 1 of the present invention. The smooth portion 261 of the windshield glass 26 according to Example 1 is wedge-shaped glass, and the uneven portion 262 has black ceramics (known as black ceramic) as the convex portions. The black ceramic is black ceramic printed on the periphery of the inside (vehicle interior) of the wedge-shaped glass. Note that the structure of the windshield glass 26 shown schematically in FIG. 1 is not wedge-shaped glass, but is intended for a configuration having a selective reflection layer, which will be described later. In the first embodiment, the projection light that has been converted into a real image by the uneven portion 141 of the intermediate image screen 14 is projected onto the wedge-shaped glass and reflected toward the observer 0, and is observed as a virtual image by the observer 0 through the windshield glass 26. In addition, the projection light that has passed through the smooth portion 142 of the intermediate image screen 14 is projected onto the black ceramic and is observed as a real image by the observer 0. The windshield glass 26 according to the first embodiment may be a commercially available product. In the windshield glass 26 according to Example 1, the uneven portion 262 may have a reflective film 70, and the reflective film 70 may be attached to the black ceramic, as in Example 3, which will be described later. In addition, in the windshield glass 26 according to Example 1, the uneven portion 262 may be a screen film 80, which will be described later, as in Example 4, which will be described later.

[0048] [Example 2] FIG. 4 is a schematic diagram showing an example of the configuration of a windshield glass 26 according to Example 2 of the present invention. The windshield glass 26 according to Example 2 includes a selective reflection film (selective reflection layer) 60, an intermediate film 62, a heat seal layer 63, two glass plates 64, and a black ceramic uneven portion 262. A polarization conversion layer (not shown) is disposed between the selective reflection film 60 and the intermediate film 62. A retardation layer (not shown) is disposed between the heat seal layer 63 and the selective reflection film 60. This retardation layer converts p-polarized light incident from the projector 10 into circularly polarized light. A transparent substrate (not shown) is disposed between the retardation layer and the heat seal layer 63. The intermediate film 62 prevents the glass from penetrating into the vehicle interior and shattering in the event of an accident. The heat seal layer 63 is an adhesive layer for attaching the reflective film to the glass plate. The windshield glass 26 according to Example 2 has a configuration in which a selective reflection film 60 is sandwiched between an intermediate film 62 and a heat seal layer 63, and this laminate is sandwiched between two glass plates 64, as illustrated in FIG. The glass sheet 64 is a typical glass sheet used for windshield glass, and may be flat, curved, or have both flat and curved surfaces. The interlayer film 62 may be made of a material typically used as an interlayer film in laminated glass for windshield glass, such as polyvinyl butyral or ethylene-vinyl acetate copolymer.

[0049] In a preferred embodiment of the projector 10, p-polarized projection light is incident on the windshield glass 26 according to Example 2. The incident p-polarized light is preferably converted into circularly polarized light and reflected by the selective reflection film 60. The selective reflection film 60 has, for example, three cholesteric liquid crystal layers: a cholesteric liquid crystal layer that selectively reflects red light, a cholesteric liquid crystal layer that selectively reflects green light, and a cholesteric liquid crystal layer that selectively reflects blue light.On the incident side, as described above, a λ / 4 retardation layer is provided, and the incident p-polarized light is converted into circularly polarized light and enters the selective reflection film 60.

[0050] All cholesteric liquid crystal layers reflect circularly polarized light of the same rotation direction. In addition, the direction of the slow axis of the λ / 4 retardation layer is set so that it converts incident p-polarized light into circularly polarized light in the rotation direction reflected by the cholesteric liquid crystal layer, depending on the circularly polarized light reflected by the cholesteric liquid crystal layer.

[0051] In such a selective reflection film 60, the λ / 4 retardation layer converts the incident p-polarized projection light into circularly polarized light, which then enters the cholesteric liquid crystal layer. The cholesteric liquid crystal layer reflects the circularly polarized projection light and causes it to again enter the λ / 4 retardation layer, which then converts the circularly polarized projection light into p-polarized projection light. As a result, the selective reflection film 60 reflects p-polarized projected light.

[0052] The smooth portion 261 of the windshield glass 26 according to Example 2 has a selective reflection film 60, and the uneven portion 262 has black ceramic as the convex portion. In Example 2, the projection light that has been made into a real image by the uneven portion 141 of the intermediate image screen 14 is reflected by the selective reflection film 60 toward the observer 0, and is observed as a virtual image by the observer 0 through the windshield glass 26. In addition, the projection light that has passed through the smooth portion 142 of the intermediate image screen 14 is projected onto the black ceramic that is the uneven portion 262, and is observed as a real image by the observer 0. A specific method for producing the windshield glass 26 according to the second embodiment will be described in detail later.

[0053] [Example 3] 5 is a schematic diagram showing a configuration example of a windshield glass 26 according to Example 3 of the present invention. As shown in FIG. 5, the windshield glass 26 according to Example 3 has the same configuration as Example 2, except that a reflective film 70 is attached to black ceramic.

[0054] The smooth portion 261 of the windshield glass 26 in Example 3 has a selective reflection film 60, and the uneven portion 262 has a reflection film 70 whose convex portions are made of black ceramic and which reflects the real image formed in the uneven portion 262 toward the observer. In Example 3, the projection light that has been made into a real image by the uneven portion 141 of the intermediate image screen 14 is reflected by the selective reflection film 60 sandwiched between the intermediate film 62 and the heat seal layer 63, and is reflected toward the observer 0, and is observed as a virtual image by the observer 0 through the windshield glass 26. In addition, the projection light that has passed through the smooth portion 142 of the intermediate image screen 14 is made into a real image by the uneven portion 262 made of black ceramic, but since black ceramic absorbs light, the brightness of the real image will be low if left as is. Therefore, in Example 3, the black ceramic Inside side (observer 0 side and same By disposing the reflective film 70 on the side (the side facing the observer 0), the light reflectance of the formed real image toward the observer 0 side is increased, thereby improving the visibility of the real image by the observer 0. The higher the reflectance of the reflective film 70, the higher the brightness of the real image. The light reflectance of the reflective film 70 can be set appropriately depending on the desired brightness. For example, it is also preferable to use the selective reflection film 60 as the reflective film 70. The method for manufacturing the windshield glass 26 according to the third embodiment will be described later.

[0055] [Example 4] Fig. 6 is a schematic diagram showing a configuration example of a windshield glass 26 according to Example 4 of the present invention. As illustrated in Fig. 6, the windshield glass 26 according to Example 4 has the same configuration as that of Example 2, except that a screen film 80, which is a reflective film, is provided. The windshield glass 26 according to Example 4 has a configuration in which a selective reflection film 60 and a screen film 80 are sandwiched between an intermediate film 62 and a heat seal layer 63, and this laminate is sandwiched between two sheets of glass 64. The screen film 80 is attached to the glass sheets 64, for example, with an adhesive film. A commercially available product may be used as the screen film 80. Examples of commercially available products include a transparent film for screens (product name: KALEIDO SCREEN (registered trademark), manufactured by KIC Corporation).

[0056] The smooth portion 261 of the windshield glass 26 according to the fourth embodiment has the selective reflection film 60, and the uneven portion 262 is the screen film 80. In Example 4, the projection light that has been converted into a real image by the uneven portion 141 of the intermediate image screen 14 is reflected by the selective reflection film 60 toward the observer 0, and is observed as a virtual image by the observer 0 through the windshield glass 26. In addition, the projection light that has passed through the smooth portion 142 of the intermediate image screen 14 is projected onto the screen film 80, and is observed as a real image by the observer 0.

[0057] [Example 5] The windshield glass 26 according to the fifth embodiment includes a dielectric multilayer film, two interlayer films 62, a heat seal layer 63, two glass sheets 64, and black ceramic. The windshield glass 26 according to Example 5 has the same configuration as Example 2, except that a dielectric multilayer film, instead of a selective reflection film 60, is sandwiched between two intermediate films 62, and this laminate is sandwiched between two glass plates 64. The dielectric multilayer film will be described later.

[0058] The smooth portion 261 of the windshield glass 26 according to the fifth embodiment has a dielectric multilayer film, and the uneven portion 262 has black ceramic as the convex portion. In the fifth embodiment, the projection light that has been converted into a real image by the uneven portion 141 of the intermediate image screen 14 is reflected by the dielectric multilayer film toward the observer 0, and is observed as a virtual image by the observer 0 through the windshield glass 26. In addition, the projection light that has passed through the smooth portion 142 of the intermediate image screen 14 is projected onto the black ceramic and is observed as a real image by the observer 0. The method for manufacturing the windshield glass 26 according to the fifth embodiment will be described later.

[0059] [Example 6] The windshield glass 26 according to the sixth embodiment has the same configuration as that of the fifth embodiment, except that a reflective film 70 is attached to the uneven portion 262 having black ceramic.

[0060] The smooth portion 261 of the windshield glass 26 according to the sixth embodiment has a dielectric multilayer film. In the sixth embodiment, the projection light that has been made into a real image by the uneven portion 141 of the intermediate image screen 14 is reflected by the dielectric multilayer film toward the observer 0, and is viewed as a virtual image by the observer 0 through the windshield glass 26. In addition, the projection light that has passed through the smooth portion 142 of the intermediate image screen 14 is made into a real image by the black ceramic. In the sixth embodiment, the same effects as those of the third embodiment are obtained by applying a reflective film 70 to the uneven portion 262.

[0061] [Example 7] The windshield glass 26 according to the seventh embodiment has the same configuration as that of the fifth embodiment, except that a screen film 80 is provided. The windshield glass 26 according to Example 7 has a configuration in which a dielectric multilayer film and a screen film 80 are sandwiched between two interlayer films 62, and this laminate is sandwiched between two glass plates 64.

[0062] The smooth portion 261 of the windshield glass 26 according to the seventh embodiment has a dielectric multilayer film, and the uneven portion 262 is the screen film 80 . In Example 7, the projection light that has been converted into a real image by the uneven portion 141 of the intermediate image screen 14 is reflected by the dielectric multilayer film toward the observer 0, and is observed as a virtual image by the observer 0 through the windshield glass 26. In addition, the projection light that has passed through the smooth portion 142 of the intermediate image screen 14 is projected onto the screen film 80, and is observed as a real image by the observer 0.

[0063] As can be understood from the above explanation, the HUD system 1 of the present invention comprises a light source 30 that emits projection light, a HUD projector 10 that has an intermediate image screen 14 that has an uneven portion 141 that converts the projection light into an image and a smooth portion 142 through which the projection light passes, and a windshield glass 26 that has an uneven portion 262 that converts the projection light that passes through the smooth portion 142 into an image. According to this embodiment, information necessary for the observer to drive a vehicle, for example, is displayed as a real image on a display surface having a different focal length from the display surface of the virtual image seen through the windshield glass 26. This allows the observer 0 to be supported in driving by presenting multifaceted information with a simple device configuration, without having to display two different virtual images in parallel through the windshield glass as in conventional head-up displays.

[0064] Next, a specific example of a method for manufacturing the windshield glass 26 according to the second embodiment will be described in detail. The methods for forming the retardation layer, polarization conversion layer, selective reflection layer, dielectric multilayer film, etc. are well known and can be manufactured by ordinary methods. The method described below is merely an example, and the present invention is not limited to the following embodiment.

[0065] <Preparation of Coating Solution for Forming Selective Reflection Layer> (Coating solution for forming cholesteric liquid crystal layer) For the coating solutions for forming cholesteric liquid crystal layers (B1, G1, R1) each having a selective reflection center wavelength (the wavelength that gives the maximum value of the reflected light intensity at an incident angle of 0°) that is the desired wavelength shown in Table 1 below, the following components are mixed to prepare coating solutions for forming cholesteric liquid crystal layers each having the following composition. ·Mixture 1 100 parts by mass Fluorine-based horizontal alignment agent 1 (alignment control agent 1) 0.05 parts by mass Fluorine-based horizontal alignment agent 2 (alignment control agent 2) 0.02 parts by mass Paliocolor LC756 (BASF), a right-handed chiral agent, was adjusted to match the target reflection wavelength. Polymerization initiator IRGACURE OXE01 (BASF) 1.0 parts by mass Solvent (methyl ethyl ketone) - Amount that makes the solute concentration 20% by mass

[0066] mixture 1 [ka]

[0067] Orientation control agent 1 [ka]

[0068] Orientation control agent 2 [ka]

[0069] The amount of the right-handed chiral agent LC756 in the coating solution composition described above is adjusted to prepare coating solutions for forming cholesteric liquid crystal layers that selectively reflect light of each wavelength of R, G, and B. Furthermore, by using each cholesteric liquid crystal layer-forming coating liquid to prepare a single cholesteric liquid crystal layer (a layer cured by a polymerization reaction) having a thickness of, for example, about 3 μm on a temporary support, it can be confirmed that the above coating liquid composition can form each selective reflection layer which is a right-handed circularly polarized light reflective layer and has a selective reflection center wavelength (center wavelength) of, for example, the wavelength shown in Table 1 below.

[0070] [Table 1]

[0071] (Coating liquid for forming retardation layer) The following components are mixed to prepare a coating liquid for forming a retardation layer having the following composition. ·Mixture 1 100 parts by mass Fluorine-based horizontal alignment agent 1 (alignment control agent 1) 0.05 parts by mass Fluorine-based horizontal alignment agent 2 (alignment control agent 2) 0.01 parts by mass Polymerization initiator IRGACURE OXE01 (BASF) 1.0 parts by mass Solvent (methyl ethyl ketone) - Amount that makes the solute concentration 20% by mass

[0072] (Polarization conversion layer forming coating liquid) The following components are mixed to prepare a coating liquid for forming a polarization conversion layer having the following composition. ·Mixture 1 100 parts by mass Fluorine-based horizontal alignment agent 1 (alignment control agent 1) 0.05 parts by mass Fluorine-based horizontal alignment agent 2 (alignment control agent 2) 0.02 parts by mass Right-handed chiral agent LC756 (BASF) Adjust to the reflection wavelength that matches the target pitch number and film thickness Polymerization initiator IRGACURE OXE01 (BASF) 1.0 parts by mass Solvent (methyl ethyl ketone) - Amount that makes the solute concentration 20% by mass

[0073] The coating solution for forming the polarization conversion layer is prepared by adjusting the amount of the right-handed chiral dopant LC756 in the coating solution composition described above so that when a cholesteric liquid crystal layer is formed, the desired selective reflection central wavelength λ is obtained. The selective reflection central wavelength λ is determined by measuring a single cholesteric liquid crystal layer with a thickness of about 3 μm on a temporary support using FTIR (Spectrum Two, manufactured by PerkinElmer). The film thickness d of the helical structure of a cholesteric liquid crystal layer can be expressed as "pitch P of the helical structure × pitch number." As mentioned above, the pitch P of the helical structure is the length of one pitch in the helical structure, and one pitch is the 360° rotation of the helically oriented liquid crystal compound. Furthermore, in a cholesteric liquid crystal layer, the selective reflection center wavelength λ is equal to "length of one pitch P × average in-plane refractive index n" (λ = P × n). Therefore, the pitch P is "selective reflection center wavelength λ / average in-plane refractive index n" (P = λ / n). For this reason, the coating liquid for forming the polarization conversion layer is prepared so that the selective reflection central wavelength λ becomes the desired wavelength when the cholesteric liquid crystal layer is formed. In the formation of the polarization conversion layer described below, this coating liquid for forming the polarization conversion layer is applied to form a polarization conversion layer with a desired film thickness, and the pitch number can be determined. Table 2 shows the combinations of the pitch number, film thickness, and selective reflection central wavelength λ (central wavelength λ) of the polarization conversion layer that are the targets of the prepared coating liquid for forming the polarization conversion layer.

[0074] [Table 2]

[0075] <Saponification of cellulose acylate film> A cellulose acylate film having a thickness of 40 μm is prepared by the same preparation method as in Example 20 of WO 2014 / 112575. UV-531 manufactured by Teisei Chemical Industry Co., Ltd. can be added to this cellulose acylate film as an ultraviolet absorber. The prepared cellulose acylate film is passed through a dielectric heating roll at a temperature of 60° C. to raise the film surface temperature to 40° C. Then, an alkaline solution having the composition shown below is applied to one side of the film using a bar coater in an amount of 14 mL / m 2 The mixture was then left to stand for 10 seconds under a steam-type far-infrared heater (manufactured by Noritake Company Limited) heated to 110°C. Next, using the same bar coater, pure water was applied at 3 mL / m 2 Apply with. Next, after repeating washing with a fountain coater and draining with an air knife three times, the film is allowed to stay in a drying zone at 70°C for 5 seconds and dried to produce a saponified cellulose acylate film (transparent substrate). The in-plane retardation of the saponified cellulose acylate film is, for example, 1 nm.

[0076] ---------------------------------------------------------------------------------- Composition of alkaline solution ---------------------------------------------------------------------------------- Potassium hydroxide 4.7 parts by mass ·Water 15.7 parts by mass Isopropanol 64.8 parts by mass Surfactants (C 16 H 33 O(CH2CH2O) 10 H) 1.0 parts by mass Propylene glycol 14.9 parts by mass ----------------------------------------------------------------------------------

[0077] <Formation of alignment film> A coating solution for forming an alignment layer having the composition shown below was applied to the saponified surface of a saponified cellulose acylate film (transparent support) at a rate of 24 mL / m using a wire bar coater. 2 Apply and dry with hot air at 100°C for 120 seconds.

[0078] ---------------------------------------------------------------------------------- Composition of coating solution for forming alignment film ---------------------------------------------------------------------------------- 28 parts by weight of the modified polyvinyl alcohol shown below Citric acid ester (AS3, manufactured by Sankyo Chemical Co., Ltd.) 1.2 parts by mass Photoinitiator (Irgacure 2959, manufactured by BASF) 0.84 parts by mass Glutaraldehyde 2.8 parts by mass ·Water 699 parts by mass Methanol 226 parts by mass ----------------------------------------------------------------------------------

[0079] (denatured polyvinyl alcohol) [ka]

[0080] <Preparation of a Laminate of a Retardation Layer, a Selective Reflection Film, and a Polarization Conversion Layer> The cellulose acylate film on which the alignment film was formed was used as a support (transparent substrate). The surface of the alignment film on the support is rubbed (rayon cloth, pressure: 0.1 kgf (0.98 N), rotation speed: 1000 rpm (revolutions per minute), conveying speed: 10 m / min, number of strokes: 1 round trip) in a direction rotated 45° clockwise from the long side of the support.

[0081] The coating liquid for forming the retardation layer is applied to the rubbed surface of the alignment film on the support using a wire bar, and then dried. Then, the specimen was placed on a hot plate at 50°C and heated with an electrodeless lamp "D bulb" (60 mW / cm) manufactured by Fusion UV Systems in an environment with an oxygen concentration of 1000 ppm or less. 2) for 6 seconds to fix the liquid crystal phase. This provides a retardation layer with a thickness adjusted to provide a desired in-plane retardation, i.e., a desired retardation. The retardation of the produced retardation layer can be, for example, 126 nm.

[0082] A coating solution for forming a cholesteric liquid crystal layer (B1) is applied to the surface of the obtained retardation layer at room temperature using a wire bar so that the thickness of the film after drying becomes 0.3 μm, thereby obtaining a coating layer. The coated layer is dried at room temperature for 30 seconds and then heated in an atmosphere at 85°C for 2 minutes. Then, in an environment with an oxygen concentration of 1000 ppm or less, it is irradiated with ultraviolet light at 60% output for 6 to 12 seconds using a Fusion D bulb (90 mW / cm lamp) at 60°C to fix the cholesteric liquid crystal phase, obtaining a cholesteric liquid crystal layer B1 with a thickness of 0.3 μm. Next, the same process is repeated using a coating liquid for forming a cholesteric liquid crystal layer (G1) on the surface of the obtained cholesteric liquid crystal layer B1 to form a cholesteric liquid crystal layer G1 having a thickness of 0.54 μm. Next, the same process is repeated using a coating liquid for forming a cholesteric liquid crystal layer (R1) on the surface of the obtained cholesteric liquid crystal layer G1 to form a cholesteric liquid crystal layer R1 having a thickness of 0.36 μm. In this way, a selective reflection layer having three cholesteric liquid crystal layers is obtained on the retardation layer.

[0083] Next, a polarization conversion layer is formed by applying the coating solution for forming a polarization conversion layer shown in Table 2 to the surface of the obtained cholesteric liquid crystal layer to the target film thickness shown in Table 2. In this way, a laminate of a retardation layer, a selective reflection film, and a polarization conversion layer is obtained. Table 3 below is a table summarizing examples of the selective reflection center wavelength and thickness of each layer constituting the cholesteric liquid crystal layer.

[0084] [Table 3]

[0085] <Windshield glass production> A windshield glass 26 having the laminate obtained above is produced as follows.

[0086] As the first and second glass plates (glass plates 64), curved glass plates (visible light transmittance 90%) measuring 1000 mm long x 1500 mm wide and 2 mm thick are prepared. As the intermediate film 62, a PVB film manufactured by Sekisui Chemical Co., Ltd. having a thickness of 0.76 mm is prepared. The heat seal layer 63 is produced as follows.

[0087] <Preparation of heat seal layer> (Coating liquid for forming heat seal layer) The following components are mixed to prepare a coating liquid for forming a heat seal layer. PVB sheet piece (S-LEC film, manufactured by Sekisui Chemical Co., Ltd.) 5.0 parts by mass Methanol 90.25 parts by mass Butanol 4.75 parts by mass

[0088] (Formation of heat seal layer) The heat seal layer forming coating liquid is applied to the laminate using a wire bar, then dried and heat treated at 50° C. for 1 minute to obtain a heat seal layer 63 having a thickness of 1 μm.

[0089] The above laminate, first glass plate, second glass plate, intermediate film 62, and heat seal layer 63 were laminated to form the configuration shown in Table 4 below, and the laminate was held at 90°C and 10 kPa (0.1 atmospheres) for 1 hour, and then heated in an autoclave (manufactured by Kurihara Seisakusho) at 115°C and 1.3 MPa (13 atmospheres) for 20 minutes to remove air bubbles. Next, black ceramic (black ceramic) is printed on the periphery of the inner side (vehicle interior side) of the second glass sheet to obtain the windshield glass 26. There are no particular limitations on the method for printing the black ceramic, but for example, a typical screen printing method is used. This printing method is described, for example, in JP 2004-058310 A.

[0090] [Table 4]

[0091] Next, an example of a specific method for manufacturing the windshield glass 26 according to the third embodiment will be described in detail.

[0092] <Windshield glass production> The windshield glass 26 can be obtained in the same manner as above, except that a laminate of a retardation layer, a selective reflection film, and a polarization conversion layer, which is produced in the same manner as in Example 2, is attached to a black ceramic substrate with an adhesive film (adhesive tape) to provide a reflective film that functions as the uneven portion 262 (see FIG. 5).

[0093] Next, an example of a specific method for producing the windshield glass 26 according to the fifth embodiment will be described in detail.

[0094] <Fabrication of dielectric multilayer film> Based on the method described in JP-A-9-506837, a dielectric multilayer film is prepared as follows.

[0095] 2,6-Polyethylene naphthalate (PEN) and a 70% naphthalate / 30% terephthalate copolyester (coPEN) are synthesized in a standard polyester resin synthesis reactor using ethylene glycol as the diol. Monolayer films of PEN and coPEN are extruded, stretched at approximately 150°C with a 5:1 draw ratio, and heat-treated at approximately 230°C for 30 seconds. The refractive index of PEN along the slow axis (orientation axis) can be approximately 1.86, the refractive index along the transverse axis can be 1.64, and the refractive index of the coPEN film can be approximately 1.64.

[0096] Then, by adjusting the stretch ratio, the refractive index of the PEN along the slow axis can be adjusted to about 1.71, that along the transverse axis to 1.64, and the refractive index of the coPEN film can be adjusted to about 1.64, i.e., the difference Δn between the refractive index of the optically anisotropic layer along the slow axis and that of the isotropic layer can be adjusted to 0.07.

[0097] Next, PEN and coPEN were co-extruded using a 25-slot feed block equipped with a standard extrusion die to obtain a laminate (44 layers) in which PEN and coPEN were alternately laminated to the thickness shown in (1) of Table 5 below. The same procedure was repeated to obtain the laminate (44 layers) shown in (2), the laminate (39 layers) shown in (3), and the laminate (38 layers) shown in (4) of Table 5. These laminates (1) to (4) were then stacked to produce a laminate with a total of 165 layers.

[0098] [Table 5]

[0099] Next, the stretched laminate is heat-treated in an air oven at about 230° C. for 30 seconds to produce a dielectric multilayer film, which can have a thickness of about 28 μm.

[0100] <Windshield glass production> The dielectric multilayer film produced by the above-mentioned method is sandwiched between two intermediate films 62, and this laminate is sandwiched between a first glass sheet and a second glass sheet to form the configuration shown in Table 6 below, thereby obtaining a windshield glass 26. Table 7 below is a table summarizing the selective reflection wavelength and thickness of each layer constituting the dielectric multilayer film according to Example 5.

[0101] [Table 6]

[0102] [Table 7]

[0103] The HUD system 1 of the present invention has been described in detail above, but the present invention is not limited to the above-described embodiments except as defined in the present invention, and various improvements and modifications can be made without departing from the spirit of the present invention, and such forms are also encompassed by the present invention. [Explanation of symbols]

[0104] 0...Observer 1. HUD system 12...Image forming unit 14...Intermediate image screen 16...Reflective member 18...Concave mirror 20…Dashboard 24...Transparent window 25...Retardation plate 26...Windshield glass 30…Light source 30R…R light source 30G…G light source 30B…B light source 32...Mirror 32R…R mirror 32G...G mirror 32B...B mirror 34...Polarizing plate 36...Light deflector 60...Reflective film 62...Interlayer 63...Heat seal layer 64...Glass plate 141,262…Uneven part 142,261...Smooth section

Claims

1. a light source that emits projection light; an intermediate image screen having a first uneven portion that converts the projected light into a real image and a first smooth portion through which the projected light passes; a projector having: a windshield glass having a second uneven portion that converts projected light passing through the first smooth portion into an actual image; A head-up display system comprising: A head-up display system, wherein the convex portions of the second uneven portion are made of black ceramics with a height of 0.3 μm or more and a width of 1.0 μm or more, and a reflective film is laminated on the same side of the second uneven portion as the observer to increase the light reflectance of the real image toward the observer.

2. 2. The head-up display system according to claim 1, wherein the windshield glass has a second smooth portion that reflects the projected light that has been imaged by the first uneven portion toward the viewer.

3. The head-up display system according to claim 2 , wherein the second smooth portion has a selective reflection layer or a dielectric multilayer film.

4. 4. The head-up display system according to claim 1, wherein the protrusions of the first concave-convex portion have a height of 0.3 μm or more and a width of 1.0 μm or more.

5. The head-up display system according to any one of claims 1 to 4, wherein the light source is a laser light source.

6. A transport aircraft equipped with the head-up display system according to any one of claims 1 to 5.

Images