Image display system and head-up display system

Abstract

The present invention relates to an image display system (100), comprising: an optical laminate (1) including an optical layer (2) that converts the polarization direction of incident light by 90° and at least one transparent resin substrate (3); a display image projection component (101) that emits S-polarized light to the aforementioned optical laminate (1); a polarization control unit (10, 10') having a P-polarization control unit that allows S-polarized light to pass through and blocks P-polarized light, or an S-polarization control unit that converts the polarization direction of incident light by 90° and blocks S-polarized light; wherein the S-polarized light reflected by the aforementioned optical laminate (1) is incident on the aforementioned polarization control unit (10, 10').

Description

Technical Field

[0001] The present invention relates to an image display system and a head-up display system equipped with the image display system. The image display system can ensure an anti-glare effect against incident light from the outside and can realize clear recognition of a displayed image. Background Art

[0002] Methods for displaying information to drivers of vehicles such as cars and airplanes include navigation systems and heads-up display (HUD) systems. A HUD is a system that projects images from an image projection component such as a liquid crystal display (LCD) onto, for example, the windshield of a car.

[0003] Light emitted from the image display unit is reflected by a reflector and then off the windshield before reaching the viewer. While the viewer sees the image projected onto the windshield, the image appears to be located farther away from the windshield. This method allows the driver to obtain a variety of information while barely shifting their gaze forward through the windshield, making it safer than conventional navigation systems that require eye movement.

[0004] Since HUDs project display information superimposed on the actual view through the windshield, they are required to present bright, easily visible images without obstructing the view. Therefore, they must achieve both transparency, allowing for sufficient visibility of the foreground, and reflectivity, allowing for sufficient visibility of the HUD display image. However, since display light is reflected by both the indoor and outdoor surfaces of the windshield, there is a problem of double images, making the displayed information difficult to see.

[0005] To address this issue, it is known that the use of an optical rotator that can change the polarization direction by 90° on an automotive windshield can alleviate the problem of reflected images becoming double images. For example, Patent Document 1 discloses that when S-polarized display light is incident at the Brewster angle on an automotive windshield equipped with a film-like optical rotator, a portion of the S-polarized light is reflected from the surface of the windshield on the inside of the vehicle. The S-polarized light that has passed through this surface is converted to P-polarized light by the optical rotator. The P-polarized light is then emitted entirely from the surface of the windshield on the outside of the vehicle, thereby preventing the occurrence of double images. Furthermore, Patent Document 1 discloses that when P-polarized display light is incident on a front windshield for an automobile at the Brewster angle, the P-polarized light is not reflected by the surface of the front windshield on the inside of the vehicle, but the P-polarized light that has passed through this surface is converted into S-polarized light by a polarization plate. Furthermore, the S-polarized light is almost entirely reflected by the surface of the front windshield on the outside of the vehicle and again converted into P-polarized light by a polarization plate, thereby preventing the generation of double images.

[0006] To reduce glare caused by reflected light from the road surface or the like, sunglasses are sometimes used. Generally, since the reflected light on the road surface has the property of becoming polarized light, it is effective to use polarized sunglasses for such reflected light. However, polarized sunglasses are generally configured to cut off the S-polarized light component in terms of their anti-glare function. Therefore, when the wearer wears polarized sunglasses, if the main component of the display light is S-polarized light, the brightness (display brightness) of the display light will be significantly reduced when the display light passes through the polarized sunglasses. Thus, the way of seeing the virtual image will change significantly depending on whether the wearer wears polarized sunglasses, so there is concern about causing a sense of discomfort to the wearer.

[0007] In Patent Document 2, it has been disclosed that when a functional glass is used for the windshield of an automobile, high visibility can be obtained even when wearing polarized sunglasses; the functional glass has a light control film laminated in such a way that a cholesteric liquid crystal layer is sandwiched between two quarter-wave plates. Specifically, after the display light of P-polarized light is incident on such a functional glass at Brewster's angle, the transmitted light is converted into circularly polarized light by the quarter-wave plate on the vehicle interior side, and the circularly polarized light is reflected by the cholesteric liquid crystal layer. On the other hand, the transmitted light that is not reflected by the cholesteric liquid crystal layer is converted back into P-polarized light by the quarter-wave plate on the vehicle exterior side and emitted to the outside of the vehicle to prevent the generation of double images. However, in this method, since it is necessary to convert from P-polarized light to circularly polarized light, the brightness may sometimes be insufficient due to the conversion efficiency. Therefore, higher visibility of the display image is required.

[0008] In Patent Document 3, it has been disclosed that in a head-up display device that projects an image using light source light containing both S-polarized light components and P-polarized light components, polarized sunglasses are used, and the polarized sunglasses adjust the blocking axis of the incident light according to the retardation value of the phase difference plate disposed on the windshield. However, according to this method, if the blocking axis is not strictly controlled, it is difficult to obtain a sufficient anti-glare effect, and there is also concern about the generation of double images.

[0009] On the other hand, inorganic glass is usually used for the windshield of a vehicle body. However, in recent years, from the viewpoints of reducing fuel consumption due to weight reduction, the integrally formed property with surrounding parts, and designability, resinification is required. When the windshield is resinified, it is not a laminated glass structure with an intermediate film, but it is expected that a single transparent resin substrate becomes the main constituent member. At this time, improvement of double images is required, and further improvement of brightness reduction affected by conversion efficiency and energy saving is also required.

[0010] [Prior Art Documents]

[0011] [Patent Documents]

[0012] Patent Document 1: Japanese Patent Laid-Open No. 6-40271

[0013] Patent Document 2: International Publication No. 2016 / 056617

[0014] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2015-225236 Summary of the Invention

[0015] [Problems to be Solved by the Invention]

[0016] The present invention provides an image display system and a head-up display system using the image display system, which can ensure an anti-glare effect against incident light from the outside and enable clear identification of a displayed image.

[0017] [Means for Solving the Problems]

[0018] As a result of dedicated research to solve the above problems, the inventor of the present invention has found that in an image display system that identifies a displayed image by reflecting S-polarized light from a display medium, by using an optical laminate having an optical layer that converts the polarization direction of incident light by 90° as the display medium and providing a polarization control unit having a predetermined polarization control function, generation of double images can be suppressed, and at the same time, reflected light from the road surface incident from the outside can be blocked from reaching the identifier, thereby achieving a sufficient anti-glare effect and clear identification of the displayed image, and finally completing the present invention.

[0019] That is, the present invention relates to the following (1) to (13). (1)

[0021] An image display system for a head-up display, comprising:

[0022] (A) An optical laminate including (a-1) an optical layer that converts the polarization direction of incident light by 90° and (a-2) at least one transparent resin substrate;

[0023] (B) A display image projection member that emits S-polarized light to the optical laminate; and

[0024] (C) A polarization control unit having (c-1) a P-polarization control unit that allows S-polarized light to pass through and blocks P-polarized light, or (c-2) an S-polarization control unit that converts the polarization direction of incident light by 90° and blocks S-polarized light; wherein

[0025] The S-polarized light reflected by the optical laminate is incident on the polarization control unit. (2)

[0027] The image display system according to (1) above, wherein the optical layer is a 1 / 2 wavelength plate. (3)

[0029] The image display system according to 1) or 2) above, wherein the optical laminate further has (a-3) at least one glass plate. 4)

[0031] The image display system according to any one of 1) to 3) above, wherein the polarization control unit has an S-polarization control unit. 5)

[0033] The image display system according to 4) above, wherein the S-polarization control unit has a retardation film (c-2a) that converts the polarization direction of incident light by 90°. 6)

[0035] The image display system according to 4) above, wherein the S-polarization control unit has a retardation film (c-2a) that converts the polarization direction of incident light by 90° and a polarizing film (c-2b) that blocks S-polarization. 7)

[0037] The image display system according to 6) above, wherein the retardation film is a half-wave plate. 8)

[0039] The image display system according to 6) or 7) above, wherein the S-polarization control unit is a laminate of the retardation film and the polarizing film. 9)

[0041] The image display system according to any one of 6) to 8) above, wherein the retardation film and the polarizing film are arranged in this order from the outside with respect to the observer as a reference. 10)

[0043] The image display system according to any one of 1) to 9) above, wherein the polarization control unit is provided in the eye wear. 11)

[0045] The image display system according to any one of 1) to 9) above, wherein the polarization control unit is provided in the sun visor in an automobile. 12)

[0047] The image display system according to 6) or 7) above, wherein the retardation film is provided in the sun visor in an automobile and the polarizing film is provided in the eye wear. 13)

[0049] The image display system according to any one of 1) to 12) above, wherein the optical layer is arranged in the following positional relationship: the angle between the polarization axis of S-polarization incident in a state inclined at Brewster's angle and the slow axis of the optical layer is within the range of 45° ± 3°. 14)

[0051] A head-up display system includes the image display system according to any one of 1) to 13) above.

[0052] [Advantages of the Invention]

[0053] According to the present invention, an image display system and a head-up display system using the image display system can be provided. The image display system can ensure an anti-glare effect against incident light from the outside and can achieve clear identification of a displayed image. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 FIG. is a schematic diagram showing an embodiment of an optical laminate included in the image display system of the present invention.

[0055] Figure 2 FIG. is a schematic diagram showing an embodiment of a polarization control unit included in the image display system of the present invention.

[0056] Figure 3 FIG. is a schematic diagram showing a first embodiment of a head-up display system including the image display system of the present invention.

[0057] Figure 4 FIG. shows the path of light when reflected light from a road surface is incident on the optical laminate in the head-up display system of Figure 3 FIG. is a schematic diagram of the path of light.

[0058] Figure 5 FIG. is a schematic diagram showing a second embodiment of a head-up display system including the image display system of the present invention.

[0059] Figure 6 FIG. shows the path of light when reflected light from a road surface is incident on the optical laminate in the head-up display system of Figure 5 FIG. is a schematic diagram of the path of light.

[0060] Figure 7 FIG. is a schematic diagram showing a third embodiment of a head-up display system including the image display system of the present invention.

[0061] Figure 8 FIG. shows the path of light when reflected light from a road surface is incident on the optical laminate in the head-up display system of Figure 7 FIG. is a schematic diagram of the path of light. DETAILED DESCRIPTION OF THE INVENTION

[0062] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the following embodiments are merely illustrative of some representative embodiments of the present invention, and various modifications can be made within the scope of the present invention. In addition, for the purpose of making the description clearer, the accompanying drawings schematically show the width, size, thickness, shape, etc. as compared with the actual state, but this is only an example. In addition, in order to illustrate the effects of the present invention, the accompanying drawings appropriately omit unnecessary parts, but the omitted parts do not limit the scope of the present invention.

[0063] The image display system of the present invention includes: (A) an optical laminate including (a-1) an optical layer that converts the polarization direction of incident light by 90° and (a-2) at least one transparent resin substrate; (B) a display image projection member that emits S-polarized light to the optical laminate; and (C) a polarization control unit having (c-1) a P-polarization control unit that allows S-polarized light to pass through and blocks P-polarized light or (c-2) an S-polarization control unit that converts the polarization direction of incident light by 90° and blocks S-polarized light. The S-polarized light reflected by the optical laminate is incident on the polarization control unit, and the observer can recognize the image displayed on the optical laminate through the S-polarized light or P-polarized light that has passed through the polarization control unit. Therefore, a virtual image reflected on the observer side of the optical laminate is recognized. On the other hand, the S-polarized light that has passed through the optical laminate is converted into P-polarized light by the optical layer, and the P-polarized light penetrates the outside of the optical laminate. As a result, the generation of double images can be significantly suppressed. In addition, external light such as the reflected light of the road surface incident from the outside of the optical laminate (the side opposite to the observation side) has a large S-polarization component. Therefore, although it is converted into P-polarized light by the optical layer, the reflected light reaching the observer is blocked by the polarization control unit. As a result, a sufficient anti-glare effect and clear recognition of the displayed image can be achieved.

[0064] Here, the observer side of the optical laminate refers to one surface of the optical laminate close to the observer (recognizer), that is, the side where the S-polarized light (hereinafter, also referred to as "display light") from the display image projection member arrives. The outside of the optical laminate means the other surface of the optical laminate far from the observer (recognizer), that is, the side where the S-polarized light from the display image projection member does not arrive and the external light arrives. In addition, taking the following observer (recognizer) as a reference, the outside means the side where the polarized light from the optical laminate is incident on the polarization control unit.

[0065] (A) Optical laminate

[0066] The optical laminate used in the image display system of the present invention includes: an optical layer and at least one transparent resin substrate. The optical laminate may further include at least one glass plate. In Figure 1In [description], it represents an embodiment of the optical laminate of the image display system of the present invention. The optical laminate 1 has an optical layer 2 and transparent resin substrates 3 disposed on both surfaces of the optical layer 2, and glass plates 4 are further provided on both surfaces of the transparent resin substrates 3. Regarding the optical laminate 1, for example, transparent resin substrates 3 can be provided on both surfaces of the optical layer 2, and they are clamped by the glass plates 4 and bonded under high temperature / high pressure for fabrication.

[0067] (a-1) Optical layer

[0068] The optical layer has the function of converting the polarization direction of incident light by 90°, that is, the function of converting P-polarized light into S-polarized light or converting S-polarized light into P-polarized light. Examples of the optical layer having such a function include a rotator, such as a 1 / 2 wavelength plate monomer with a retardation of 1 / 2 of the desired wavelength, a laminate of multiple retardation plates, such as a laminate of two 1 / 4 wavelength plates, etc. Among these, the optical layer is preferably a 1 / 2 wavelength plate.

[0069] (1 / 2 wavelength plate)

[0070] The 1 / 2 wavelength plate is a retardation element having the function of converting P-polarized light into S-polarized light or converting S-polarized light into P-polarized light, that is, the function of converting the polarization axis. For example, it can be obtained by uniaxially stretching a film made of polycarbonate or cycloolefin polymer so that the retardation becomes 1 / 2 of the wavelength, or by orienting a horizontally aligned polymerizable liquid crystal to a thickness with a retardation of 1 / 2 of the wavelength. Generally, a 1 / 2 wavelength plate using a horizontally aligned polymerizable liquid crystal is composed of: a polymerizable liquid crystal layer as the layer having the function of converting the polarization axis; and a support substrate for coating the coating liquid that forms the polymerizable liquid crystal layer. From the viewpoint of the orientation of the liquid crystal, the upper limit value of the thickness of such a 1 / 2 wavelength plate is preferably 10 μm or less, more preferably 5 μm or less. On the other hand, from the viewpoint of the polymerizability of the liquid crystal, the lower limit value of the thickness of the 1 / 2 wavelength plate is preferably 0.3 μm or more, more preferably 0.5 μm or more. When light is incident from a position inclined with respect to the surface of the 1 / 2 wavelength plate, the retardation sometimes changes with the incident angle of the light. In such a case, in order to accurately make the retardation appropriate, for example, by using a retardation element whose refractive index is adjusted, the change of the retardation with the incident angle can be suppressed. For example, when the refractive index in the slow axis direction in the plane of the retardation element is nx, the refractive index in the direction in the plane and orthogonal to nx of the retardation element is ny, and the refractive index in the thickness direction of the retardation element is nz, the coefficient Nz shown in the following formula (1) is preferably controlled to be 0.3 or more and 1.0 or less, more preferably controlled to be 0.5 or more and 0.8 or less.

[0071] Nz = (nx - nz) / (nx - ny) (1)

[0072] In an image display device using such a half-wave plate, in order to efficiently convert S-polarized light into P-polarized light, it is preferable to control the angle θ formed between the polarization axis of the S-polarized light incident from a position inclined by 45° or more and 65° or less with respect to the axis perpendicular to the surface of the optical laminate and the slow axis of the half-wave plate to be 35° or more and 47° or less. By setting the incident angle of the S-polarized light incident on the half-wave plate to be in the range of 45° or more and 65° or less, the reflectance of the P-polarized light can be theoretically controlled to be 2% or less, and the generation of double images can be suppressed. That is, the incident S-polarized light is reflected on the surface of the optical laminate, and this S-polarized light reaches the observer. The transmitted S-polarized light is converted into P-polarized light by the half-wave plate, and the converted P-polarized light passes through without being reflected at the interface between the optical laminate on the opposite side of the incident side and the air. In this way, by controlling the incident angle of the S-polarized light incident on the optical laminate, the generation of double images can be suppressed. In addition, when the angle θ is less than 35° or greater than 47°, the polarization axis conversion performance of converting the S-polarized light incident on the optical laminate into P-polarized light is low. As a result, the display image on the display also becomes darker, and when using eye wear, there is a concern about deteriorating its anti-glare effect. Therefore, by appropriately controlling this angle θ, the half-wave plate exhibits good polarization axis conversion performance. As a result, the display image can be recognized more clearly.

[0073] When the half-wave plate includes a polymerizable liquid crystal layer, a liquid crystal composition that will form the polymerizable liquid crystal layer is coated on a support substrate. Regarding such a support substrate, when the half-wave plate is used in a HUD, in order to maintain the recognizability of the display image, in the visible light region, it is preferably transparent. Specifically, as long as the transmittance of visible light with a wavelength of 380 nm or more and 780 nm or less is 50% or more, it is preferably 70% or more, and more preferably 85% or more. In addition, the support substrate may be colored, but it is preferably uncolored or slightly colored. Further, the refractive index of the support substrate is preferably 1.2 or more and 2.0 or less, and more preferably 1.4 or more and 1.8 or less. The thickness of the support substrate can be appropriately selected according to the use, and is preferably 5 μm or more and 1000 μm or less, more preferably 10 μm or more and 250 μm or less, and particularly preferably 15 μm or more and 150 μm or less.

[0074] The support substrate may be a single layer or a laminate of two or more layers. Examples of the material of the support substrate include, for example, triacetyl cellulose (TAC), acrylic acid, polycarbonate, polyvinyl chloride, polyolefin, and polyethylene terephthalate (PET). Among these, triacetyl cellulose (TAC), polyolefin, and acrylic acid with less birefringence are preferred.

[0075] Next, a method for fabricating a half-wave plate using the above-described nematic liquid crystal monomer having a polymerizable group will be described. For such a method, for example, a nematic liquid crystal monomer having a polymerizable group is dissolved in a solvent, and then a photopolymerization initiator is added. Such a solvent is not particularly limited as long as it can dissolve the liquid crystal monomer used, but examples thereof include cyclopentanone, toluene, methyl ethyl ketone, and methyl isobutyl ketone, and cyclopentanone and toluene are preferred. Thereafter, the solution is coated on a plastic substrate such as a PET film or a TAC film used as a support substrate so as to have as uniform a thickness as possible, and the solvent is removed by heating. At the same time, it is placed for a certain period of time under temperature conditions such that the liquid crystal is aligned on the support substrate. At this time, by performing a rubbing treatment on the surface of the plastic substrate in a desired alignment direction in advance before coating, or by forming a photo-alignment material that exhibits photo-alignment properties by polarized light irradiation on the surface of the plastic substrate in advance and performing polarized light irradiation or other alignment treatments, the alignment of the liquid crystal can be made more uniform. Accordingly, the slow axis of the half-wave plate can be controlled to a desired angle, and the haze value of the half-wave plate can be reduced. Then, by irradiating the nematic liquid crystal monomer with ultraviolet light using a high-pressure mercury lamp or the like while maintaining this alignment state to fix the alignment of the liquid crystal, a half-wave plate having a desired slow axis can be obtained.

[0076] The main function of the half-wave plate used as the optical layer is to convert the S-polarized light that is not reflected on the surface but transmitted into P-polarized light. Accordingly, the reflection from the transparent substrate disposed outside the optical laminate is reduced, and the generation of double images can be suppressed. In addition, light from the outside such as reflected light on the road surface is also converted into P-polarized light. The wavelength dispersion of the half-wave plate is not particularly limited, but it is preferably suitable for use in a head-up display. In particular, in order to correctly perform polarization conversion in a wide wavelength range in the visible light region, it is desirable for the half-wave plate to have inverse wavelength dispersion. Generally, polymers exhibit normal dispersion in which the absolute value of birefringence increases on the short wavelength side. However, for a liquid crystal compound in which the birefringence Δn value for each wavelength of visible light is controlled so that the birefringence increases on the long wavelength side, inverse wavelength dispersion can be obtained. In addition, inverse wavelength dispersion can also be obtained by laminating a plurality of retardation plates having appropriate retardation corresponding to the wavelength dispersion characteristics of the liquid crystal compound with an appropriate combination of slow axes. In addition, in order to efficiently change the S-polarized light into P-polarized light, it is preferable to dispose the half-wave plate as the optical layer at a positional relationship such that the angle between the polarization axis of the S-polarized light incident in a state inclined at Brewster's angle and the slow axis of the half-wave plate is within the range of 45° ± 3°, and this angle is more preferably within the range of 45° ± 2° and even more preferably within the range of 45° ± 1°.

[0077] (a-2) Transparent resin substrate

[0078] The optical laminate has at least one transparent resin substrate, and preferably has two transparent resin substrates. At this time, it is preferable to sandwich the optical layer with two transparent resin substrates. The two transparent resin substrates may be the same as each other or different from each other, but it is preferable that they are the same. The transparent resin substrate is not particularly limited, but it is preferably suitable for the use of a head-up display. At this time, there are certain limitations on the visible light transmittance and haze value. For example, the visible light transmittance is preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, particularly preferably 85% or more, and most preferably 90% or more. In addition, the haze value is preferably 2% or less, more preferably 1% or less, and still more preferably 0.5% or less. In addition, the transparent resin substrate preferably does not have optical anisotropy.

[0079] The thickness of the transparent resin substrate is preferably 0.5 mm or more and 25 mm or less. The upper limit of the thickness of the transparent resin substrate is more preferably 20 mm, and still more preferably 15 mm. In addition, the lower limit of the thickness of the transparent resin substrate is more preferably 0.6 mm, and still more preferably 0.7 mm. Examples of the transparent resin substrate include acrylic resins such as cyclic olefins, polyethersulfone, polyarylate, polyethylene terephthalate, polycarbonate resin, polymethyl methacrylate, ABS (acrylonitrile / butadiene / styrene) resin, polyphenylene ether resin, and the like. Among these, polycarbonate resin, polymethyl methacrylate resin, and polyvinyl butyral are preferred. The transparent resin substrate may be a single type or a laminate of two or more layers.

[0080] In particular, polycarbonate resin is preferred because of its excellent transparency, high impact absorption, improved safety during collision, excellent impact resistance, and not being easily damaged in a minor collision. Among polycarbonate resin, acrylic resin, cyclic olefin resin, polyphenylene ether resin, etc., a thermoplastic resin other than the main component resin can be blended within the range that does not damage the characteristics of the present invention and used as a resin composition. In addition, when the optical laminate further includes a glass plate described later and the optical laminate layer is supported or sandwiched by the glass plate, the transparent resin substrate is preferably polyvinyl butyral. In addition, when the (a-3) glass plate is disposed on one side of the optical laminate, it is expressed as support, and when disposed on both sides, it is expressed as sandwiching.

[0081] (a-3) glass plate

[0082] The optical laminate layer may further include a glass plate, which can be used as a functional glass supported or clamped by the glass plate. For example, if the functional glass is used as a front windshield, there is no particular limitation as long as it has sufficient transparency to clearly identify the scenery ahead. In addition, the refractive index of the glass plate is preferably 1.2 or more and 2.0 or less, and more preferably 1.4 or more and 1.8 or less. In addition, the thickness, shape, etc. of the glass plate are not particularly limited as long as they do not affect the reflection of the display light, and can be appropriately designed according to the use. In addition, among these glass plates, an antireflection film composed of a multilayer film, a metal thin film having an insulation function, etc. may be provided on the reflection surface. These films can increase the reflectivity of the incident polarized light, but when using the functional glass as a front windshield for automobiles, it is preferable to adjust the reflectivity so that the visible light transmittance of the functional glass becomes 70% or more. In addition, in the glass plate, for example, it also includes a glass having a curved shape like a windshield.

[0083] The method of laminating the glass plate to the optical laminate layer is preferably, for example, using a thermoplastic resin as the transparent resin substrate, clamping the optical layer between two thermoplastic resins, and then clamping with two glasses and performing press bonding under high temperature / high pressure. At this time, the thermoplastic resin is preferably, for example, a polyvinyl butyral resin (PVB), a polyvinyl alcohol resin (PVA), or an ethylene-vinyl acetate copolymer resin (EVA), and more preferably PVB. The thickness and hardness of the two transparent resin substrates are not particularly limited as long as they do not affect the reflection of the display light, and can be appropriately designed to cut off functions such as UV, heat insulation, sound insulation, or light control. In addition, the thickness and hardness of the two transparent resin substrates may be the same or different from each other, but it is preferable that they are different.

[0084] The functional glass obtained in this way can be used as the front windshield, side glass, rear glass, and top glass of ordinary automobiles, small cars, light cars, etc., as well as large special automobiles and small special automobiles. In addition, the functional glass can also be used as the windows of railway vehicles, ships, and airplanes. In addition, it can also be used as building materials and industrial window materials. Regarding the use form of the functional glass, it can be laminated or bonded with a member having at least one function of a UV cut-off function, a heat insulation function, a sound insulation function, and a light control function and used.

[0085] (B) Display image projection component

[0086] In the image display system of the present invention, the display image projection component of the image display system that emits S-polarized light emits display light with an incident angle on the surface of the optical laminate being an angle near the Brewster angle. Here, the angle near the Brewster angle means that when the Brewster angle of S-polarized light with respect to the surface of the optical laminate is α, the incident angle of S-polarized light incident on the optical laminate is in the range of α - 10° or more and α + 10° or less. If the S-polarized light from the display image projection component is incident on the optical laminate at an angle near the Brewster angle, a lot of S-polarized light will be reflected and reach the observer, so the observer can recognize the virtual image. On the other hand, the S-polarized light that cannot be reflected on the surface of the optical laminate and penetrates the optical laminate is converted into P-polarized light by the optical layer, and the converted P-polarized light penetrates the optical laminate. As a result, reflection from the outside of the optical laminate can be prevented, and the generation of double images can be suppressed. In addition, if the light reaching the display image projection component is S-polarized light, the light emitted from the display image projection component can be P-polarized light. At this time, since the emitted P-polarized light must be converted into S-polarized light, for example, it is preferable to have a half-wave plate before the P-polarized light reaches the optical laminate.

[0087] (C) Polarization control unit

[0088] The image display system of the present invention includes a polarization control unit, and the polarization control unit has: (c-1) a P-polarization control unit that allows S-polarized light to pass through and blocks P-polarized light; or (c-2) an S-polarization control unit that converts the polarization direction of the incident light by 90° and blocks S-polarized light. Regarding the P-polarization control unit that allows S-polarized light to pass through and blocks P-polarized light, for example, a polarized sunglasses made by setting the absorption axis of the polarization filter perpendicular so that the lens itself allows S-polarized light to pass through and blocks P-polarized light can be cited; or a polarization film that allows S-polarized light to pass through and blocks P-polarized light by setting the absorption axis of the polarization filter perpendicular, etc.

[0089] The S-polarization control unit preferably has a retardation film (c-2a) that converts the polarization direction of the incident light by 90°, that is, a retardation film that converts P-polarized light into S-polarized light or S-polarized light into P-polarized light. Examples of such a retardation film include a 1 / 2 wavelength plate. In addition, the S-polarization control unit preferably has, in addition to the retardation film, a polarizing film that blocks S-polarized light or polarized sunglasses that block S-polarized light. Examples of the polarizing film that blocks S-polarized light include a polarizing film whose absorption axis is horizontal with respect to the S-polarized light reflected from the road surface, that is, the S-polarized light incident on the polarizing film. In addition, examples of the polarized sunglasses that block S-polarized light include polarized sunglasses whose absorption axis of the polarizing filter is horizontal with respect to the S-polarized light incident on the polarizing filter. Among these, the S-polarization control unit preferably has (c-2a) a retardation film that converts the polarization direction of the incident light by 90° and (c-2b) a polarizing film that blocks S-polarized light. In particular, when using the retardation film and the polarizing film together, the S-polarization control unit can be a laminate of the retardation film and the polarizing film that blocks S-polarized light. These can be arranged separately, but the retardation film and the polarizing film are preferably arranged in this order from the outside with respect to the observer as a reference.

[0090] Figure 2 FIG. is a schematic diagram showing an embodiment of the polarization control unit included in the image display system of the present invention. The polarization control unit 10 is an S-polarization control unit including a retardation film 10B and a polarizing film 10A that blocks S-polarized light. In Figure 2 FIG., the retardation film 10B is arranged on the outside of the polarizing film 10A with respect to the observer as a reference. Therefore, the polarization direction of the polarized light incident on the polarization control unit 10 is converted by 90° by the retardation film 10B. When the converted polarized light is S-polarized light, the S-polarized light is blocked by the polarizing film 10A, and when the converted polarized light is P-polarized light, the P-polarized light passes through the polarizing film 10A and reaches the observer. In addition, in Figure 2 the polarization control unit 10 shown in FIG., the retardation film 10B and the polarizing film 10A are separately arranged, but the polarization control unit 10 can also be a laminate of the retardation film 10B and the polarizing film 10A. Details will be described below, but examples of separately arranging the retardation film 10B and the polarizing film 10A include a method of attaching the retardation film 10B to a general polarized sunglass with a fixture (Clip On type) when the retardation film 10B is arranged on a sun visor and an eyewear with the polarizing film 10A is used. In addition, when the polarization control unit 10 is a laminate of the retardation film 10B and the polarizing film 10A, for example, a state in which a composite film in which the retardation film 10B and the polarizing film 10A are bonded with an adhesive or binder is used for eyewear can be exemplified.

[0091] When the S-polarization control unit is a combination of a half-wave plate as a retardation film and a polarizing film whose absorption axis is horizontal with respect to the polarization axis of the S-polarization incident on the polarizing film, methods for recognizing a display image include mounting a composite film in which these are overlapped or adhered on an automotive sun visor or an eye-wear, and recognizing the display image through the composite film. In addition, methods include mounting a half-wave plate as a retardation film on an automotive sun visor and mounting a polarizing film on an eye-wear, and recognizing the display image with the eye-wear through the half-wave plate provided on the automotive sun visor. When these methods are used in an HUD equipped with an image display system, it is preferable that the size of the retardation film mounted on the automotive sun visor matches the display range of the image of the head-up display. Accordingly, the influence on other in-vehicle displays such as a navigation system, gauges, instrument panels, and electronic mirrors of a central control unit designed considering the recognizability of the display image can be reduced in ordinary polarizing sunglasses whose absorption axis is horizontal.

[0092] When the S-polarization control unit is a combination of a half-wave plate as a retardation film and polarizing sunglasses whose absorption axis is horizontal with respect to the polarization axis of the S-polarization incident on the polarizing filter, methods for providing a half-wave plate in the polarizing sunglasses include, for example, a method of mounting sunglasses having a half-wave plate as an overglass on ordinary polarizing sunglasses; a method of mounting with a jig on ordinary polarizing sunglasses (clip-on type), etc. Mounting of the overglass and the clip-on type are preferable because the blocking of polarization can be easily switched during recognition of the display image and at other normal times, and a normal anti-glare effect can be obtained at normal times. In particular, in the case of the clip-on type, by making the jig openable and closable, the blocking of polarization can be switched more easily. In addition, a method of adhering a film containing a half-wave plate on the surface of ordinary polarizing sunglasses with an adhesive or binder can also be used. The adhesive and binder are not particularly limited, but when the half-wave plate is configured to be detachable, an adhesive having excellent reworkability is preferable. For example, a silicone adhesive or an acrylic adhesive having excellent transparency is preferable. As other methods, a method of molding a lens in which a half-wave plate is pre-inserted on the light incident side of the polarizing filter in the lens configuration of the polarizing sunglasses can also be cited.

[0093] In a configuration where a 1 / 2 wavelength plate is disposed on the light incident side of a general polarizing sunglasses in which the absorption axis of the polarizing filter is horizontal with respect to the polarization axis of the S-polarized light incident on the polarizing filter, in order to efficiently convert S-polarized light into P-polarized light or efficiently convert P-polarized light into S-polarized light, it is preferable to control the angle θ formed by the polarization axis of the linearly polarized light and the slow axis of the 1 / 2 wavelength plate to be 35° or more and 47° or less. When the angle θ is less than 35° or greater than 47°, the polarization axis conversion performance for converting the S-polarized light incident on the 1 / 2 wavelength plate into P-polarized light is low. As a result, the display image on the display also becomes darker, and there is a concern that the anti-glare effect of the eye wear is impaired when used. Therefore, by appropriately controlling the angle θ, the 1 / 2 wavelength plate exhibits good polarization axis conversion performance. As a result, the display image can be recognized more clearly. In addition, the wavelength dispersion of the 1 / 2 wavelength plate is not particularly limited as long as it is suitable for the use of eye wear, but in order to correctly perform polarization conversion in a wide wavelength range in the visible light region, it is desirable to have inverse wavelength dispersion.

[0094] <First Embodiment>

[0095] Figure 3 FIG. is a schematic diagram showing an embodiment of a head-up display system including the image display system of the present invention. As Figure 3 shown, the HUD system (image display system) 100 of the present embodiment includes: a display image projection unit 101 that emits S-polarized light as display light for displaying a display image; an optical laminate 1 into which the S-polarized light emitted from the display image projection unit 101 is incident; and a polarization control unit 10' that serves as a P-polarization control unit. The S-polarized light emitted from the display image projection unit 101 is reflected by a mirror 102, and the reflected display light reaches the optical laminate 1. The optical laminate 1 is as Figure 1 shown and has: an optical layer 2, transparent resin substrates 3 on both sides of the optical layer 2, and glass plates 4 on both outer sides of the transparent resin substrates 3.

[0096] In the HUD system configured as described above, the incident light 201 of the S-polarized light emitted from the display image projection unit 101 is incident on the optical laminate 1 at an incident angle near the Brewster angle. The incident light 201 is reflected at the interface between the surface of the optical laminate 1 on the observer side and the air, generating reflected light 202. Since the reflected light 202 is S-polarized light, even if the polarization control unit 10' having a P-polarization control unit that blocks P-polarized light is used, the S-polarized light directly passes through. Therefore, the passed reflected light 202 is recognized by the observer as a display image.

[0097] Incident light 201 that is incident on the optical stack 1 without being reflected as reflected light 202 is transmitted through the optical stack 1 and converted into P-polarized light by the optical layer 2. The incident light 201 that has been converted into P-polarized light is transmitted at a position close to the Brewster angle between the interface between the glass plate 4 and air, which is disposed outside the optical stack 1. Therefore, the reflected light at this interface becomes substantially zero, and the incident light 201 that has been converted into P-polarized light passes through the optical stack 1 as transmitted light 203.

[0098] on the other hand, Figure 4 is Figure 3 In the HUD system (image display system) 100, the path of light when the reflected light from the road surface is incident on the optical stack 1 is displayed. The reflected light from the road surface contains many S-polarized light components, so the S-polarized light is incident from the outside of the optical stack 1. The incident S-polarized light is transmitted in the optical stack 1 and converted into P-polarized light through the optical layer 2. The incident light 204 converted into P-polarized light is further transmitted in the optical stack 1. If it penetrates the optical stack 1, the incident light 204 does not penetrate due to the polarization control unit 10' having a P-polarized light control unit that blocks the P-polarized light, and is blocked by the polarization control unit 10'. Therefore, the penetrating light is essentially 0, preventing the reflected light from the outside (outside the vehicle) from reaching the observer.

[0099] <Second embodiment>

[0100] Figure 5 FIG. 1 is a schematic diagram showing another embodiment of a head-up display system including the image display system of the present invention. Figure 5 As shown, the HUD system (image display system) 100 of this embodiment includes: a display image projection component 101 that emits S-polarized light as display light for displaying a display image; an optical laminate 1 on which the S-polarized light emitted from the display image projection component 101 is incident; and a phase difference film 10B that converts the polarization direction of the incident light by 90 degrees as an S-polarized light control unit, and a polarizing film 10A that blocks the S-polarized light. Figure 5 In the optical laminate, a phase difference film 10B and a polarizing film 10A are arranged separately. The phase difference film 10B is arranged outside the polarizing film 10A with respect to the observer, that is, on the side where polarized light from the optical laminate 1 is incident. Figure 3 Similarly, the S-polarized light emitted from the display image projection unit 101 is reflected by the reflector 102, and the reflected display light reaches the optical stack 1. The optical stack 1 is as shown in FIG. Figure 1 As shown, it includes an optical layer 2 , a transparent resin substrate 3 on both sides of the optical layer 2 , and glass plates 4 on both outer sides of the transparent resin substrate 3 .

[0101] In such a HUD system, Figure 3Similarly, the incident light 201 of S-polarized light emitted from the display image projection component 101 is incident on the optical laminate 1 at an incident angle near the Brewster angle. The incident light 201 is reflected at the interface between the surface of the optical laminate 1 on the observer side and the air, generating reflected light 202. Since the reflected light 202 is S-polarized light, the reflected light 202 is converted into P-polarized light by the retardation film 10B. Even if the polarized light film 10A that blocks S-polarized light is used, the reflected light 202 that has been converted into P-polarized light directly passes through. Therefore, the passed reflected light 202 will be recognized by the observer as a display image.

[0102] In addition, the incident light 201 that is not reflected as the reflected light 202 and is incident on the optical laminate 1 is the same as Figure 3 Similarly, it is transmitted in the optical laminate 1 and is converted into P-polarized light by the optical layer 2. The incident light 201 that has been converted into P-polarized light is transmitted at an angle near the Brewster angle at the interface between the glass plate 4 disposed outside the optical laminate 1 and the air. Therefore, the reflected light at this interface is substantially zero, and the incident light 201 that has been converted into P-polarized light passes through the optical laminate 1 as transmitted light 203.

[0103] On the other hand, Figure 6 is in Figure 5 the HUD system (image display system) 100, showing the light path when the reflected light from the road surface is incident on the optical laminate. Similar to Figure 4 the reflected light from the road surface contains a lot of S-polarized light components, so the S-polarized light is incident from the outside of the optical laminate 1. The incident S-polarized light is transmitted in the optical laminate 1 and is converted into P-polarized light by the optical layer 2. The incident light 204 that has been converted into P-polarized light is further transmitted in the optical laminate 1. If it passes through the optical laminate 1, since the transmitted light 204 is P-polarized light, it is converted into S-polarized light by the retardation film 10B. The transmitted light 204 that has been converted into S-polarized light is blocked by the polarized light film 10A that blocks S-polarized light. Therefore, the transmitted light is substantially zero, preventing the reflected light from the outside (outside the vehicle) from reaching the observer.

[0104] <Third Embodiment>

[0105] Figure 7 is a schematic diagram showing an embodiment of a head-up display system equipped with the image display system of the present invention. As Figure 7As shown, the HUD system (image display system) 100 of the present embodiment includes: a display image projection component 101 that emits S-polarized light as display light for displaying a display image; an optical stack 1 on which the S-polarized light emitted from the display image projection component 101 is incident; and a polarization control unit 10 that directly stacks a phase difference film 10B and a polarizing film 10A as an S-polarization control unit. In the polarization control unit 10, the phase difference film 10B is arranged on the outside of the polarizing film 10A with the observer as a reference, that is, on the side on which the polarized light from the optical stack 1 is incident. The S-polarized light emitted from the display image projection component 101 is reflected by the reflector 102, and the reflected display light reaches the optical stack 1. The optical stack 1 is as shown Figure 1 As shown, it includes an optical layer 2 , a transparent resin substrate 3 on both sides of the optical layer 2 , and glass plates 4 on both outer sides of the transparent resin substrate 3 .

[0106] In such a HUD system, Figure 3 Similarly, the incident light 201 of S polarization emitted from the display image projection component 101 is incident on the optical stack 1 at an angle of incidence near the Brewster angle. The incident light 201 is reflected at the interface between the surface of the observer side of the optical stack 1 and the air, generating reflected light 202. Because the reflected light 202 is S polarization, it is converted into P polarization by the phase difference film 10B in the polarization control unit 10, which is a stack of the phase difference film 10B and the polarizing film 10A. The reflected light 202 converted into P polarization passes through the polarizing film 10A, which blocks S polarization, as P polarization. Therefore, the reflected light 202 that passes through is recognized by the observer as a displayed image.

[0107] Incident light 201 that is not reflected as reflected light 202 but enters the optical laminate 1 is incident on the optical laminate 1. Figure 3 Similarly, incident light 201 propagates through the optical stack 1 and is converted into P-polarized light by the optical layer 2. The incident light 201 converted into P-polarized light propagates at a position close to the Brewster angle at the interface between the glass plate 4 and air, which is disposed outside the optical stack 1. Therefore, the reflected light at this interface becomes substantially zero, and the incident light 201 converted into P-polarized light passes through the optical stack 1 as transmitted light 203.

[0108] on the other hand, Figure 8 is Figure 7 In the HUD system (image display system) 100, the path of light when reflected light from the road surface is incident on the optical stack is displayed. Figure 4Similarly, the reflected light from the road surface contains a lot of S-polarized light components, so the S-polarized light is incident from the outside of the optical laminate 1. The incident S-polarized light is transmitted through the optical laminate 1 and is converted into P-polarized light by the optical layer 2. The incident light 204 converted into P-polarized light is further transmitted through the optical laminate 1. If it penetrates the optical laminate 1, since the transmitted light 204 is P-polarized light, in the polarization control unit 10 belonging to the laminate of the retardation film 10B and the polarizing film 10A, it is converted into S-polarized light by the retardation film 10B. The transmitted light 204 converted into S-polarized light is blocked by the polarizing film 10A that blocks S-polarized light. Therefore, the transmitted light substantially becomes zero, preventing the reflected light from the outside (outside the vehicle) from reaching the observer.

[0109] [Industrial Applicability]

[0110] Even in a head-up display using the S-polarized light type, the image display system of the present invention can recognize and display an image without a sense of incongruity. On the other hand, it can also sufficiently ensure the anti-glare effect against external light. Therefore, it is possible to ensure the anti-glare effect against external incident light and to realize the recognition of a clear display image. Such an image display system can be used for the application of a head-up display system. In addition, the layer structure of the optical laminate is not complicated, so it can also contribute to the simplification of the manufacturing process.

[0111] Explanation of Reference Numerals

[0112] 1: Optical laminate

[0113] 2: Optical layer

[0114] 3: Transparent resin substrate

[0115] 4: Glass plate

[0116] 10, 10': Polarization control unit

[0117] 10A: Polarizing film

[0118] 10B: Retardation film

[0119] 100: Head-up display system, image display system

[0120] 101: Display image projection component

[0121] 102: Mirror

[0122] 201: Incident light

[0123] 202: Reflected light

[0124] 203, 204: Transmitted light.

Claims

1. An image display system, comprising: An optical laminate including an optical layer that converts the polarization direction of incident light by 90°, at least one transparent resin substrate, and two glass plates; A display image projection component that emits S-polarized light to the optical laminate; And A polarization control unit having a P-polarization control unit that transmits S-polarized light and blocks P-polarized light, or an S-polarization control unit that converts the polarization direction of incident light by 90° and blocks S-polarized light; wherein, The optical layer is a 1 / 2 wavelength plate; In the optical laminate, the optical layer and the transparent resin substrate are sandwiched between the two glass plates; The S-polarized light reflected by the optical laminate is incident on the polarization control unit; and The S-polarized light contained in the light from the outside incident from the outside of the optical laminate is converted into P-polarized light by the optical layer, and the polarization control unit prevents the S-polarized light contained in the light from the outside from reaching the observer, The incident light of S-polarized light emitted from the display image projection component is incident on the optical laminate at an incident angle near the Brewster angle, The incident light converted into P-polarized light is transmitted at an angle near the Brewster angle at the interface between the glass plate disposed outside the optical laminate and air.

2. The image display system according to claim 1, wherein The polarization control unit has an S-polarization control unit.

3. The image display system according to claim 2, wherein, The S-polarization control unit has a retardation film that converts the polarization direction of incident light by 90°.

4. The image display system according to claim 2, wherein, The S-polarization control unit has a retardation film that converts the polarization direction of incident light by 90° and a polarizing film that blocks S-polarized light.

5. The image display system according to claim 4, wherein, The retardation film is a 1 / 2 wavelength plate.

6. The image display system according to claim 4 or 5, wherein, The S-polarization control unit is a laminate of the retardation film and the polarizing film.

7. The image display system according to claim 4 or 5, wherein, The retardation film and the polarizing film are arranged in this order from the outside with the observer as a reference.

8. The image display system according to claim 1 or 2, wherein, The polarization control unit is provided in an ocular wear.

9. The image display system according to claim 1 or 2, wherein The polarization control unit is provided in an automotive sun visor.

10. The image display system according to claim 4 or 5, wherein, The automotive sun visor is provided with the retardation film, and the ocular wear is provided with the polarizing film.

11. The image display system according to claim 1 or 2, wherein The optical layer is arranged in the following positional relationship: the angle between the polarization axis of the S-polarized light incident in a state inclined at the Brewster angle and the slow axis of the optical layer is in the range of 45° ± 3°.

12. The image display system according to claim 1 or 2, wherein The light from the outside is reflected light.

13. A head-up display system, comprising the image display system according to any one of claims 1 to 12.

Images