Windshield glass and head-up display systems

Abstract

To provide a windshield glass which allows visual recognition of display by a head-up display even when sunglasses are worn and a head-up display system including the windshield glass.SOLUTION: A windshield glass having a display region of a head-up display includes: two glass plates comprising an indoor-side first glass plate and an outdoor-side second glass plate; and an intermediate member provided between the two glass plates. The intermediate member includes an interlayer and a retardation film provided in the display region. The retardation film is made of a photo-aligned liquid crystalline material.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a windshield glass having a display area for a head-up display, and a head-up display system. [Background technology]

[0002] Laminated glass, which has a basic structure of two sheets of glass with an interlayer film sandwiched between them, is widely used as windshield glass for vehicles such as automobiles and trains, and aircraft. Among windshield glasses, the glass placed in front of the driver (for example, the front glass of a vehicle) is used for head-up displays, and characters and images of instrument panels, etc., may be projected and displayed in the display area. In such cases, various research projects are being conducted to improve the visibility of the display area while ensuring forward visibility through the windshield glass.

[0003] Patent Document 1 (JP 2010-79197 A) describes that by using an anisotropic scattering film having a dielectric matrix and metal nanorods oriented in a fixed direction in the dielectric matrix as a film for a head-up display and placing this in laminated glass, the projection light emitted from the viewer's side is anisotropically scattered and reflected to ensure the visibility of the projection light while also achieving visibility of transmitted light such as scenery.

[0004] Patent Document 2 (Utility Model Registration No. 3210995) describes a full-time head-up display system in which a wedge-shaped plate and a half-wave plate are placed between the two pieces of glass that make up the windshield, and describes how the half-wave plate converts S-waves (S-polarized light) and P-waves into each other, and how the wedge-shaped plate superimposes the reflected images of the two pieces of glass to prevent overlapping images.

[0005] Patent Document 3 (JP 2016-153281 A) describes a windshield glass having a projection image display area and including two glass plates and an intermediate layer having a wedge-shaped cross-sectional shape, and describes that by providing this windshield glass with a half-mirror film including a cholesteric liquid crystal layer at least in the projection image display area, it is possible to eliminate double images and improve brightness, and further describes that a 1 / 2λ retardation layer may be provided. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2010-79197 A [Patent Document 2] Utility model registration No. 3210995 [Patent Document 3] JP 2016-153281 A Summary of the Invention [Problem to be solved by the invention]

[0007] When an image is projected onto a windshield made of laminated glass, a double image is observed due to the difference in the optical path between the light reflected from the inner glass and the light reflected from the outer glass. For this reason, in the past, the intermediate layer between the inner glass and the outer glass was made to have a wedge-shaped cross section to eliminate the double image. In addition, since glass mainly reflects S waves, the brightness of S waves increases when an image projected onto the windshield glass is viewed with the naked eye, but if the pilot is wearing polarized sunglasses that absorb S waves, it becomes difficult to view the image.

[0008] Patent Document 1 describes that the visibility of the display area of ​​a head-up display is improved by using an anisotropic scattering film, but does not consider the visibility when wearing sunglasses. In addition, as specific examples, the use of palladium nanorods and gold-core silver-shell nanorods is considered, and it is difficult to suppress the manufacturing cost.

[0009] In Patent Document 2, light including S waves (S polarized light) and P waves (P polarized light) is projected, and the S waves are converted to P waves and the P waves are converted to S waves by a half wave plate. In this case, the projected P waves pass through the inner glass (viewer's side), are converted to S waves when passing through the half wave plate, are reflected by the outer surface of the outer glass, and are converted to P waves when passing through the half wave plate again, so that the pilot can see it even if he is wearing sunglasses. However, the projected S waves are still not visible through sunglasses. In addition, when viewed with the naked eye, the part of the projected S waves that passes through the inner glass is converted to P waves by the half wave plate, and most of it passes through the outer glass and is emitted to the outside, so only the S waves reflected by the inner glass can be seen. In addition, the optical characteristics of the part where the half wave plate is installed are different from those of other parts, so that the boundary is visible.

[0010] Patent Document 3 describes that a head-up display system can be provided that can display a high-brightness projected image with reduced double images, and can provide a clear projected image even when viewed through polarized sunglasses. For this reason, the windshield glass uses a cholesteric liquid crystal layer that selectively reflects circularly polarized light of either right-handed or left-handed sense in a specific wavelength range and transmits circularly polarized light of the other sense in a half-mirror film, and multiple cholesteric liquid crystal layers with different central wavelengths of reflection are arranged so that the cholesteric liquid crystal layer closest to the incident side of the projection light has the longest central wavelength of selective reflection. However, such a configuration makes the intermediate layer complicated, and the manufacturing process of the windshield glass requires complicated processes.

[0011] The present invention aims to provide a windshield glass that has a projection light display area for a head-up display, is manufactured by a simple method, is compatible with polarized sunglasses, and easily eliminates double images, and a head-up display equipped with the windshield glass. [Means for solving the problem]

[0012] The windshield glass of the present invention is A windshield glass having a display area for a head-up display, The window glass comprises two glass plates, a first glass plate on the indoor side and a second glass plate on the outdoor side, and an intermediate member disposed between the two glass plates; The intermediate member is a windshield glass including an intermediate film and a retardation film provided in the display area, the retardation film being made of a photo-alignable liquid crystal material.

[0013] According to the windshield glass having the above configuration, by imparting a phase difference to the light reflected by the second glass on the outside of the vehicle, the viewer can view the displayed image even when wearing polarized sunglasses.

[0014] In the above windshield glass, the photo-alignable liquid crystal material constituting the retardation film may be tilted with respect to the surface of the first glass plate. In such a windshield glass, by tilting the photo-alignable liquid crystal material, different phase differences are imparted to light that enters the windshield glass and passes through the retardation film and light that is reflected by the outer surface of the windshield glass and passes through the retardation film, thereby increasing the amount of light emitted to the viewer and suppressing changes in color tone.

[0015] In the above windshield glass, the retardation film may be configured so that, in its outer circumferential region, the thickness thereof becomes continuously thinner toward the outer edge.

[0016] In the windshield glass having the above-mentioned structure, the boundary between the display area provided with the retardation film and other areas is prevented from becoming conspicuous, and the design can be improved.

[0017] In the above windshield glass, the retardation film may be provided as a coating film between the intermediate film and the first glass plate. By forming the retardation film as a coating film of a photo-alignable liquid crystal material, it becomes possible to arbitrarily adjust the thickness distribution of the retardation film.

[0018] The head-up display system of the present invention comprises: A windshield glass including two glass sheets, a first glass sheet on the indoor side and a second glass sheet on the outdoor side, and an intermediate member disposed between the two glass sheets; A head-up display system including: a projection device that projects light onto the windshield glass, The head-up display system is characterized in that the intermediate member includes an intermediate film and a retardation film provided in the display area, the retardation film being made of a photo-alignable liquid crystal material.

[0019] In the above-described head-up display system, a phase difference is applied to the light reflected by the windshield glass, so that the viewer can view the displayed image even when wearing polarized sunglasses.

[0020] In the head-up display system, At least in the display area, the gap between the two glass plates has a constant thickness; the photo-alignable liquid crystal material constituting the retardation film is tilted relative to the surface of the first glass plate, the projection device projects the light onto the windshield glass as a P wave so that the angle of incidence with respect to the windshield glass is Brewster's angle; The present invention may be a head-up display system characterized by the above-mentioned.

[0021] In the head-up display system having the above-described configuration, by making the retardation film of the windshield glass contain an inclined, photo-oriented liquid crystal material, it is possible to prevent the formation of double images even if the distance between the two glass plates is constant, i.e., even if the thickness of the intermediate member is constant. Effect of the Invention

[0022] According to the windshield glass and the head-up display system equipped with the same of the present invention, the windshield glass is provided with a retardation film made of a photo-alignable liquid crystalline material, thereby imparting a phase difference to the reflected light from the outer glass, thereby ensuring good visibility. [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic cross-sectional view for explaining a basic configuration of a windshield glass and a head-up display system according to an embodiment of the present invention. [Figure 2A] FIG. 2 is a perspective view for illustrating the alignment state of a photoalignable liquid crystal material constituting a retardation film. [Figure 2B] FIG. 13 is a perspective view for illustrating another alignment state of a photoalignable liquid crystal material constituting a retardation film. [Diagram 3] 1 is a schematic cross-sectional view for explaining a state in which a viewer visually recognizes light projected onto a windshield glass according to one embodiment of the present invention, showing a case in which S waves are projected. FIG. [Figure 4] FIG. 1 is a schematic cross-sectional view for explaining the state in which a viewer perceives light projected onto a windshield glass according to one embodiment of the present invention, and shows the case in which S waves are projected using a retardation film in which a photo-alignable liquid crystalline material is inclined. [Diagram 5] FIG. 2 is a schematic cross-sectional view for explaining a state in which a viewer visually recognizes light projected onto a windshield glass according to one embodiment of the present invention, showing a case in which a P wave is projected. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a schematic cross-sectional view for explaining the basic configuration of a windshield glass 10 and a head-up display system 100 of the present invention. Note that the size ratios of the various parts in the following drawings do not indicate the actual ratios. Furthermore, when used as the front windshield of a vehicle, for example, the windshield glass 10 often has a curved surface, but for the sake of simplicity of explanation, a partially enlarged cross section near the display area A is shown, and the outline of the windshield glass 10 is illustrated as a straight line.

[0025] The windshield glass 10 of the present invention comprises a first glass plate 1 arranged on the inside of the vehicle (the viewer VE side), a second glass plate 2 arranged on the outside of the vehicle, and an intermediate member 3 sandwiched between the first glass plate 1 and the second glass plate 2.

[0026] Characters and images displayed by the head-up display system 100 are projected from a projection device 20 onto a display area A of the windshield glass 10, and a virtual image formed by light reflected from the inner surface 1a of the first glass plate 1 and light reflected from the outer surface 2b of the second glass plate 2 is usually observed by the viewer VE. Here, the "inner surface" refers to the surface facing the viewer VE, and the "outer surface" refers to the surface facing the outside of the vehicle. The inner surface 1a of the first glass plate 1 and the outer surface 2b of the second glass plate 2 refer to the surface of the windshield glass 10 facing the viewer VE and the surface facing the outside of the vehicle, respectively.

[0027] In the present invention, the intermediate member 3 of the laminated glass structure is composed of an intermediate film 4 and a retardation film 5, and the retardation film 5 is provided in the display area A. In other words, an image of the head-up display system 100 is displayed in the area A where the retardation film 5 is provided. The retardation film 5 is formed as a coating film of a liquid crystalline material having photoalignment properties. Preferably, the film thickness t of the retardation film 5 becomes continuously thinner in the outer periphery.

[0028] The retardation film 5 is provided in a display area A where images, characters, etc. are displayed by light projected from a projection device 20. The retardation film 5 may be provided only in the display area A. Here, the display area A refers to the area including the entire thickness of the windshield glass 10, from the area on the inner surface 1a of the first glass 1 where light is projected from the projection device 20 to the area on the outer surface 2b of the second glass 2 where the incident light is reflected.

[0029] The windshield glass 10 may be made up of only the above-mentioned first glass 1, second glass, and intermediate member 3 made up of interlayer film 4 and retardation film 5. Alternatively, in addition to the above-mentioned basic structure, other components may be included. For example, wiring for a heater (not shown) may be provided in the intermediate member 3.

[0030] The photo-alignable liquid crystal material constituting the retardation film 5 may be a material constituting a nematic liquid crystal phase. FIGS. 2A and 2B are schematic perspective views for explaining the alignment of the liquid crystal material in the retardation film 5. Here, the liquid crystal material LC is shown in a spindle shape for explaining the alignment, but these do not represent the actual shape or distribution density. For example, in the case of a photo-alignable liquid crystal material represented by the chemical formula described below, the alignment of the liquid crystal material LC shown in the figures reflects the alignment of the mesogens of the liquid crystal polymer.

[0031] As shown in Fig. 2A, the liquid crystalline material LC may be aligned substantially parallel to the bottom surface 5a of the retardation film 5 (which corresponds to the interface between the retardation film 5 and the first glass plate 1 in the configuration of Fig. 1), or as shown in Fig. 2B, the liquid crystalline material LC may be aligned at an angle to the bottom surface 5a of the retardation film 5.

[0032] 3 is a schematic cross-sectional view for explaining the configuration of a windshield glass according to one embodiment of the present invention. In this embodiment, in the cross section of the windshield glass 100, the distance d between the outer surface 1b of the first glass plate 1 and the inner surface 2a of the second glass plate 2 is continuously reduced in one direction, and the intermediate member 3 sandwiched between the two glass plates 1 and 2 has a wedge-shaped cross section. The retardation film 5 is formed on the outer surface 1b of the first glass plate 1 as a coating film of a liquid crystalline material having photoalignment properties, and the film thickness t of the retardation film 5 is continuously reduced in the outer periphery.

[0033] The retardation film 5 is provided in an area where an image of the head-up display system 100 is displayed (image display area A in FIG. 1).

[0034] As an example, when S waves are projected as the projection light LP from the projection device 20 (FIG. 1) of the head-up display system 100 onto the windshield glass 10, the reflected light LR1 reflected by the inner surface 1a of the first glass plate 1 is an S wave, but the incident light LI incident on the windshield glass 10 is converted into elliptically polarized light by the retardation film 5. The P wave component passes through the outer surface 2b of the second glass plate 2 and exits, so the reflected light LR2 reflected by the outer surface 2b of the second glass plate 2 is mainly an S wave component. This reflected light LR2 is converted into elliptically polarized light by the retardation film 5 and exits toward the viewer VE. Therefore, even if the viewer VE is wearing polarized sunglasses that absorb S waves, the viewer VE can view the projected image due to the P wave component of the reflected light LR2 that has passed through the sunglasses. In Figure 3 and the following Figures 4 and 5, black circles on the lines showing the optical paths indicate S waves, arrows indicate P waves, and rotating arrows indicate elliptically polarized light.

[0035] In the above embodiment, the thickness t of the retardation film 5 is continuously reduced at the outer edge, so that when the viewer VE looks outside through the windshield glass, the boundary between the display area and other parts is not clearly visible, and good visibility and design can be obtained. The liquid crystal material LC constituting the retardation film may be oriented almost parallel to the inner surface of the first glass as in the example shown in FIG. 2A. Alternatively, it may be oriented at an inclination as in the example shown in FIG. 2B. For example, by adjusting the angle of the inclination orientation, almost no light incident on the windshield glass is converted, and only the light reflected by the outer surface 2b of the second glass plate 2 and emitted to the indoor side is converted into elliptically polarized light.

[0036] For example, Fig. 4 shows a modified example of the embodiment shown in Fig. 3. In this example, the liquid crystal material LC is tilted in the direction indicated by the arrow D, and the incident light LI incident on the windshield glass 10 is hardly given a phase difference and is reflected as an S wave by the outer surface 2b of the second glass plate 2. The reflected light LR2 is converted into elliptically polarized light by the retardation film 5 and is emitted to the viewer VE side. Therefore, the amount of reflected light LR2 is increased, and visibility can be improved both with the naked eye and when wearing polarized sunglasses 30.

[0037] 5 is a diagram showing another embodiment of a windshield glass 10 and a head-up display system 100 according to the present invention. In this embodiment, the distance d between the outer surface 1b of the first glass plate 1 and the inner surface 2a of the second glass plate 2 is constant, and the thickness of the intermediate member 3 is constant. Here, for the sake of simplicity, only the display area of ​​the windshield glass 10 is shown, but even in this embodiment, the film thickness t of the retardation film 5 may be thinner at the outer edge.

[0038] If the light LP projected from the projection device 20 onto this windshield glass is a P wave and the incident angle φ with respect to the first glass plate 1 is the Brewster angle, the projected light LP enters the windshield glass without being reflected, and the incident light LI is converted into elliptically polarized light by the retardation film 5. The S wave component of this elliptically polarized light is reflected and converted into elliptically polarized light by the retardation film, and is viewed by the viewer VE.

[0039] In the above example, the projected light LP is not reflected by the first glass plate 1, and only the reflected light LR2 from the second glass plate 2 is visible, so that even if the first glass plate 1 and the second glass plate 2 are substantially parallel and the cross section of the intermediate member 3 is not wedge-shaped, no double image is observed. This simplifies the design of the laminated glass structure of the windshield glass 10 and the manufacturing process. In addition, since the light emitted to the viewer VE side is elliptically polarized light, even if the viewer VE is wearing polarized sunglasses 30, the viewer VE can view the displayed image with the P-wave component.

[0040] In the above embodiment, when the light incident on the windshield glass 10 is converted from P waves to elliptically polarized light by the retardation film 5, in order to increase the reflected S wave component, it is advantageous for the retardation film 5 to provide a relatively large phase difference close to 1 / 2 wavelength. Since the S waves reflected by the outer surface 2b of the second glass plate 2 are converted back into elliptically polarized light when passing through the retardation film 5, the light emitted from the windshield glass 10 to the viewer VE side does not darken when viewed through the polarized sunglasses 30.

[0041] As a modification of the embodiment shown in FIG. 5, the photo-oriented liquid crystal material constituting the retardation film 5 may be tilted. Since the retardation given by the retardation film 5 differs for each wavelength of light, if the retardation film 5 is made to give a large retardation close to 1 / 2 wavelength in the above embodiment, when the viewer VE observes the reflected light LR2 from the second glass plate 2 through the polarized sunglasses 30, there is a possibility that a change in color tone (coloring) is observed for the projected light P. By tilting the photo-oriented liquid crystal material, a phase difference close to 1 / 2 wavelength is given to the incident light LI when it passes through the retardation film 5, and the phase difference given when the reflected light LR2 reflected from the second glass plate passes through the retardation film 5 is suppressed, thereby suppressing the change in color tone visually perceived by the viewer VE.

[0042] [Head-up display system] The head-up display system 100 according to the present invention includes at least the windshield glass 10 according to the present invention and a projection device 20 that projects light onto the display area A of the windshield glass 10. The head-up display system 100 may be a system for a vehicle such as an automobile, and in that case, the windshield glass 10 may be the front glass of the vehicle. The projection device is a device that projects (projects) characters, images, etc. with light, and may be, for example, a device that is incorporated into a vehicle as an in-vehicle display for a head-up display, or may be a device that can be installed on a dashboard or the like as a device independent of the vehicle. In addition, it may be a device that can connect a smartphone or the like and project the information thereof onto the windshield glass 10.

[0043] [Retardation film] In the above embodiment, the retardation film 5 is made of a photo-alignable liquid crystal material, and the alignment is fixed. The retardation film 5 may be one in which the liquid crystal material is in-plane aligned (aligned parallel to the bottom surface of the film) as shown in FIG. 2A, or one in which the liquid crystal material is tilted aligned as shown in FIG. 2B. By using a tilted retardation film, a phase difference that is imparted to light incident on the windshield glass 10 and a phase difference that is different from that imparted to light reflected by the outer surface 2b of the outer glass 2 can be imparted. In the present invention, a solution containing a liquid crystal material exhibiting photo-alignment is applied to a glass plate serving as a support, and the liquid crystal material is aligned in a predetermined direction by a process involving light irradiation and heating, so that the characteristics of the retardation film 5 can be expressed. Therefore, it is easy to arbitrarily control the film thickness distribution, and the retardation characteristics can also be easily controlled by controlling the alignment direction.

[0044] [Liquid crystal materials exhibiting photoalignment] As a liquid crystalline material exhibiting photoalignment, for example, a liquid crystalline material that contains a photosensitive group in at least a portion of the side chain and is composed of at least a polymer having a side chain represented by any one of the chemical formulas 1 to 3 below can be used. [ka] [ka] [ka] In each of the chemical formulas 1 and 2, n represents an integer of 1 to 12, and m represents an integer of 1 to 12, independently; X and Y represent none, -COO-, -OCO-, -N=N-, -C=C-, or -CH-, respectively; W1 and W2 represent a cinnamoyloxy group, a chalcone group, a cinnamylidene group, a biphenylacryloyloxy group, a furylacryloyloxy group, a naphthylacryloyloxy group, or a derivative thereof, or represent -H, -OH, or -CN; and in the chemical formula 3, s represents 0 or 1, t represents an integer of 1 to 3, and R represents H, an alkyl group, an alkyloxy group, or a halogen.

[0045] When the above liquid crystalline material is used, the side chains having photosensitive groups are oriented in a specific direction by exposure to polarized light or exposure to pseudo-parallel light from an oblique direction, and even if the liquid crystalline material contains side chains having no photosensitive groups, these are oriented according to the neighboring oriented side chains during the heating and cooling process, and the orientation is fixed to form the retardation film 5. The specific process can be performed under the following conditions.

[0046] [Paint film formation] A liquid crystalline polymer formed from monomer units having side chains represented by the above chemical formulas 1 to 3, and optionally a low molecular weight compound and other components (such as a polymerization catalyst) are added to the above liquid crystalline polymer, and these are dissolved in a suitable solvent to prepare a coating liquid, which is then coated on a substrate, and the solvent is removed to form a liquid crystalline polymer layer on the substrate.

[0047] Examples of the solvent include dioxane, dichloroethane, dimethyl ether, diglyme, cyclohexanone, toluene, tetrahydrofuran, o-dichlorobenzene, methyl ethyl ketone, and methyl isobutyl ketone. These solvents may be used alone or in combination.

[0048] In the present invention, a glass plate constituting a windshield glass is usually used as a support. By applying a liquid crystal material onto a glass plate, an arbitrary film thickness distribution can be obtained, so that a retardation film can be formed at an arbitrary position on a glass substrate with an arbitrary film thickness distribution. Therefore, for example, as in the above embodiment, the thickness of the retardation film can be continuously (gradually) thinned at the outer edge. The method of applying the coating liquid is not particularly limited, but for example, a spray gun or the like may be used to apply the coating liquid onto a glass plate serving as a support.

[0049] [exposure] After applying the coating liquid onto a support and drying to the extent that the solvent is removed, the coating film is exposed to polarized light (for example, linearly polarized ultraviolet light) or pseudo-parallel light from an oblique direction to form an alignment layer in which the liquid crystalline material is in-plane aligned or obliquely aligned. When the coating film is irradiated with linearly polarized light, a retardation film in which the liquid crystalline material is aligned parallel to the surface of the substrate (glass plate) can be formed. 。

[0050] The exposure may be carried out during drying (before complete drying). After the exposure, the sample is preferably heated to 80 to 130° C., preferably 100 to 120° C., and then cooled.

[0051] [Glass plate] The glass plates constituting the first glass plate 1 and the second glass plate 2 can be inorganic glass or organic glass such as polycarbonate or acrylic. When glass is used as a base material for forming the retardation film 3b, it is preferable to use inorganic glass in order to ensure heat resistance. As the inorganic glass, inorganic glass such as soda-lime glass, which is usually used to form windshield glass, borosilicate glass, alkali-free glass, and quartz glass can be used.

[0052] [Interlayer] The resin constituting the interlayer film may be a commercially available optically transparent adhesive, in addition to polyvinyl butyral, which has been conventionally used as an interlayer film for laminated glass. In order to ensure the weather resistance of the retardation film, a UV-absorbing optically transparent adhesive may be used. EXAMPLES

[0053] (Monomer 1) 4-(6-hydroxyhexyloxy)cinnamic acid was synthesized by heating p-coumaric acid and 6-chloro-1-hexanol under alkaline conditions. This product was esterified with a large excess of methacrylic acid in the presence of p-toluenesulfonic acid to synthesize monomer 1 shown in the following chemical formula 4.

[0054] [ka]

[0055] (Monomer 2) p-Hydroxybenzoic acid and 6-chloro-1-hexanol were heated under alkaline conditions to synthesize 4-(6-hydroxyhexyloxy)benzoic acid. This product was esterified with a large excess of methacrylic acid in the presence of p-toluenesulfonic acid to synthesize monomer 2 shown in the following chemical formula 5.

[0056] [ka]

[0057] (Polymer 1) Monomer 1 and monomer 2 were dissolved in dioxane in a molar ratio of 5:95, and AIBN was added as a reaction initiator. The mixture was polymerized at 70°C for 24 hours to obtain photosensitive polymer 1. This polymer 1 exhibited liquid crystallinity.

[0058] [Example 1: Preparation of laminated glass] Polymer 1 was prepared as a 15 wt% solution of DME / diglyme = 1 / 2.5. This solution was applied to half of the glass substrate using a spray gun, and the remaining half was coated so that the thickness gradually changed to thinner and the area near the edge was left uncoated. This substrate was irradiated with pseudo-parallel light from a high-pressure mercury lamp from an oblique direction. It was then heated to 130°C to form an inclined alignment layer. This glass substrate was bonded to another glass substrate with a transparent adhesive to form laminated glass. When this glass substrate was visually inspected, the boundary between the coated and uncoated areas was not discernible.

[0059] [Example 2: S-polarized light irradiation] The glass substrate having the laminated glass structure produced in Example 1 was placed in a position simulating a windshield glass (front glass of a vehicle) in a head-up display system, and an image (character display) emitted from a projection device (projector) was projected onto the glass substrate as an S-wave using a polarizing plate. When the reflected light was visually observed through a polarizing plate whose absorption axis was parallel to the S-wave, the characters projected on the coated area could be confirmed, whereas the reflected light was absorbed by the polarizing plate in the uncoated area, and the projected characters could not be recognized.

[0060] [Example 3: P-polarized light irradiation] The glass substrate having the laminated glass structure prepared in Example 1 was placed in a position simulating a windshield glass (front glass for a vehicle) in a head-up display system, and an image (character display) emitted from a projection device (projector) was projected onto the glass substrate as a P wave using a polarizing plate. At that time, the incident angle of the P wave was adjusted to be the Brewster angle. When this was visually observed with the naked eye, the reflected light was weak in the uncoated part of the polymer 1, making it difficult to recognize the image, but in the coated part of the polymer 1, the displayed image could be recognized by the reflected light, and the occurrence of double images was also suppressed. When the reflected light was visually observed through a polarizing plate whose absorption axis was parallel to the S wave, the image projected on the coated part could be seen without darkening.

[0061] [Example 4: Preparation of laminated glass with in-plane alignment of photoalignable liquid crystal material] Polymer 1 was dissolved in a solvent of dimethyl ether / diglyme=1 / 2.5 by volume to prepare a 15 wt% solution. This solution was applied to half of the glass substrate using a spray gun, and the other half was coated so that the thickness gradually changed and became thinner, and the vicinity of the end became a non-coated portion. The substrate was irradiated with linearly polarized light from a high-pressure mercury lamp directly above. The substrate was then heated to 130°C to form an orientation layer. This glass substrate was laminated with another glass substrate using a transparent adhesive to form a laminated glass. When this glass substrate was visually observed, the boundary between the coated portion and the non-coated portion could not be recognized. In addition, an image projected with P waves was also visible as in Example 3, but when observed through a polarizing plate, a change in the color tone of the image was observed.

[0062] [Comparative Example 1] As in Example 2, a glass substrate (flat plate) was placed in a position simulating a windshield glass (front glass of a vehicle) in a head-up display system, and an image emitted from a projection device (projector) was converted into S-waves by a polarizing plate and projected onto the glass substrate. When viewed with the naked eye, the image was visible, but the occurrence of double images was noticeable. [Industrial Applicability]

[0063] INDUSTRIAL APPLICABILITY The windshield glass and head-up display system using the same of the present invention have a simple configuration and can provide a display image that can be seen even when wearing sunglasses, and are highly useful in head-up displays on the windshield of a vehicle. [Explanation of symbols]

[0064] 1. First Glass 1a Inner surface of first glass 1b Outer surface of first glass 2. Second Glass 2a Inner surface of second glass 2b Outer surface of second glass 3 Intermediate parts 4 Interlayer 5 Retardation film 10 Windshield Glass 20 Projection device 30 Polarized sunglasses A Display area LC liquid crystal material LP projection light LI incident light LR1 Reflected light from the first glass LR2 Reflected light from the second glass d Distance between the first and second glass panes t Retardation film thickness VE Viewer

Claims

1. A windshield glass having a display area for a head-up display, The present invention provides a window pane that includes two glass sheets, a first glass sheet on the indoor side and a second glass sheet on the outdoor side, and an intermediate member disposed between the two glass sheets, The intermediate member includes an intermediate film and a retardation film provided in the display area, the retardation film being made of a liquid crystal material having optical alignment properties aligned in one direction.

2. 2. The windshield glass according to claim 1, wherein the photo-alignable liquid crystal material constituting the retardation film is aligned at an angle with respect to the surface of the first glass plate.

3. The windshield glass according to claim 1 or 2, A windshield glass, wherein the retardation film is gradually thinner in its peripheral region toward its outer edge.

4. The windshield glass according to any one of claims 1 to 3, A windshield glass, wherein the retardation film is provided as a coating film between the intermediate film and the first glass plate.

5. A windshield glass including two glass sheets, a first glass sheet on an indoor side and a second glass sheet on an outdoor side, and an intermediate member disposed between the two glass sheets; A head-up display system including: a projection device that projects light onto the windshield glass, A head-up display system, wherein the intermediate member includes an intermediate film and a retardation film provided in the display area, the retardation film being made of a photo-alignable liquid crystal material oriented in one direction.

6. 6. The head-up display system according to claim 5, The thickness of the intermediate member is constant, the photo-alignable liquid crystal material constituting the retardation film is tilted with respect to the surface of the first glass plate, the projection device projects the light onto the windshield glass as a P wave so that the angle of incidence with respect to the windshield glass is Brewster's angle; A head-up display system.

Images