Image display system and vehicle

Abstract

To provide a video display system capable of making it difficult to visually recognize a reflected image in an interior of a video formed on a transparent screen.SOLUTION: A video display system comprises: a projection device that is arranged inside a vehicle, and projects an image; and a transparent screen that visibly displays the image projected from the projection device to an observer inside or outside the vehicle as a video, and it satisfies the following formula 1; (D+B)-(P+DOF / 2)≥410 ... Formula 1. In formula 1, D is a distance [mm] between the projection device and the transparent screen, B is a distance [mm] between the transparent screen and an interior material of the vehicle, P is a distance [mm] where the projection device is just in focus, and DOF is a depth of focus [mm] of the projection device.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a video display system including a transparent screen, and a vehicle equipped with the video display system. [Background technology]

[0002] There is an advertising method that uses the exterior surfaces of vehicles such as buses, trucks, and passenger cars (for example, taxis, commercial vehicles, MaaS) (see, for example, Patent Document 1). Furthermore, Patent Document 2 describes using vehicle windows as advertising media.

[0003] In the video display system described in Patent Document 2, a transparent screen is provided on a window (side window or rear window) of a vehicle. An advertisement video is projected onto the transparent screen from a projection device installed inside the vehicle. The video can be seen from outside the vehicle.

[0004] Patent Document 3 describes an example of a reflective transparent screen. The reflective transparent screen can be installed on a window of a vehicle. When the reflective transparent screen is installed on a window of a vehicle, an image is projected onto the reflective transparent screen from a projection device installed inside the vehicle, for example. The image can be viewed from inside the vehicle. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-293250 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-113230 [Patent Document 3] Japanese Patent Publication No. 2020-129052 Summary of the Invention [Problem to be solved by the invention]

[0006] FIG. 10 is an explanatory diagram showing an example of the installation state of a projection device in a vehicle and a method of using the projection device. In the example shown in FIG. 10, a projector 410, which is an example of a projection device, is installed inside a vehicle 400. A transparent screen 420 is also installed on a window of the vehicle. In an environment such as that shown in FIG. 10, when an image is projected from the projector 410 onto the transparent screen 420, a problem occurs in that a reflected image of the image formed on the transparent screen 420 is reflected on an interior material (e.g., the surface of a seat; hereinafter, referred to as the interior). It is believed that there are quite a few people who find the reflected image reflected on the interior annoying. In FIG. 10, an area 500 indicates the area into which the reflected image is reflected.

[0007] The above problem can occur whether the transparent screen 420 is a transmissive transparent screen or a reflective transparent screen.

[0008] The above problem can be alleviated by increasing the distance between the transparent screen 420 and the area where the reflected image is projected. However, unlike outdoors or the interior of a typical building, the size of the interior of a vehicle and the degree of freedom in arranging the interior are limited. For example, the length, width, and height of a vehicle must comply with the laws, regulations, and safety standards of each country. As a result, it is difficult to increase the distance between the transparent screen 420 and the interior. Therefore, it is desirable to solve the problem by making the reflected image of the image less visible using a method other than increasing the distance between the transparent screen 420 and the interior.

[0009] An object of the present invention is to provide an image display system that can make it difficult to see the reflected image of an image formed on a transparent screen on an interior décor. [Means for solving the problem]

[0010] The image display system according to the present invention is arranged inside a vehicle and comprises a projection device that projects an image, and a transparent screen that displays the image projected from the projection device as an image visible to an observer inside or outside the vehicle, and satisfies the following formula 1. (D+B)-(P+DOF / 2)≧410...Equation 1 In Equation 1, D is the distance [mm] between the projection device and the transparent screen, B is the distance [mm] between the transparent screen and the vehicle's interior material, P is the distance [mm] at which the projection device is exactly in focus, and DOF is the depth of focus [mm] of the projection device.

[0011] A vehicle according to the present invention is equipped with the above-described image display system, and a transparent screen is installed in a window portion. [Effects of the Invention]

[0012] According to the present invention, it is possible to make it difficult to see the reflected image of the image formed on the transparent screen on the interior of the vehicle. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a video display system. [Figure 2] FIG. 10 is a schematic diagram showing another example of a video display system. [Figure 3] FIG. 1 is a cross-sectional view showing an example of a reflective transparent screen. [Figure 4] FIG. 10 is a cross-sectional view showing another example of a reflective transparent screen. [Figure 5] FIG. 1 is a cross-sectional view showing an example of a transmission type transparent screen. [Figure 6] FIG. 10 is a schematic diagram for explaining distance relationships and the like. [Figure 7] FIG. 10 is an explanatory diagram for explaining a method for measuring illuminance. [Figure 8] FIG. 10 is an explanatory diagram showing parameter values ​​and the like in Examples and Comparative Examples. [Figure 9] FIG. 10 is an explanatory diagram for explaining a method for determining whether or not there is a reflection. [Figure 10] 1 is an explanatory diagram showing an example of an installation state of a projection device in a vehicle and a method of using the projection device. DETAILED DESCRIPTION OF THE INVENTION

[0014] FIG. 1 is a schematic diagram showing an example of an image display system. The projection device in the image display system shown in FIG. 1 is installed, for example, inside a vehicle, and the side of the screen on which an observer 700, who is a passenger, of the image is located is referred to as the "interior of the vehicle." The image display system shown in FIG. 1 includes a projector 410, which is an example of a projection device, and a reflective transparent screen 100. The reflective transparent screen 100 displays the image projected from the projector 410 as an image visible to the observer 700 inside the vehicle, and is installed, for example, on a window of the vehicle. Note that the image viewed by the observer 700 by the image display system shown in FIG. 1 is a real image. The reflective transparent screen 100 is a flat screen or a curved screen. The projector 410 projects an image onto the reflective transparent screen 100. The observer 700 views the image due to the light reflected from the reflective transparent screen 100. The observer 700 is an occupant of the vehicle. Examples of window parts include windshields, rear windows, side windows, roofs, and quarter windows.

[0015] The DLP system, the transmissive liquid crystal system, and the reflective liquid crystal system are examples of the projection system of the projector 410. The DLP system is preferable from the viewpoint of increasing brightness, resolution, and contrast.

[0016] FIG. 2 is a schematic diagram showing another example of an image display system. The projection device in the image display system shown in FIG. 2 is installed, for example, inside a vehicle, and therefore the side where an observer 710 of the image outside the vehicle is present is referred to as "outside the vehicle." The image display system shown in FIG. 2 includes a projector 410, which is an example of a projection device, and a transmissive transparent screen 200. The transmissive transparent screen 200, which displays the image projected from the projector 410 as an image visible to the observer 710 outside the vehicle, is installed, for example, on a window of the vehicle. The transmissive transparent screen 200 is a flat screen or a curved screen. The observer 710 views the image formed by light transmitted through the transmissive transparent screen 200.

[0017] (Example of a reflective transparent screen) 3 is a cross-sectional view showing an example of a reflective transparent screen that can be used in this embodiment. The reflective transparent screen 101 shown in FIG. 3 is an example of the reflective transparent screen 100 shown in FIG.

[0018] The reflective transparent screen 101 is formed by sandwiching a reflective image display layer 50 and a resin film 43 serving as a support member for supporting the image display layer 50 between a first transparent substrate 11 and a second transparent substrate 12. A first interlayer film 21 and a second interlayer film 22 are interposed between the reflective image display layer 50 and the resin film 43 on the one hand and the first transparent substrate 11 and the second transparent substrate 12 on the other. The first interlayer film 21 serves to bond the first transparent substrate 11 and the image display layer 50 on the other hand. The second interlayer film serves to bond the second transparent substrate 12 and the resin film 43 on the other hand. The first interlayer film 21 and the second interlayer film 22 may be in contact with each other at the periphery of the reflective transparent screen 101. In other words, the reflective image display layer 50 may be located inside the interlayer film. 3, one resin film 43 is provided as a support member, but another support member may be provided on the opposite side of the resin film 43 with respect to the image display layer 50. Also, the resin film 43 may not be provided. In this case, the reflective image display layer 50 is in contact with the first interlayer film 21 and the second interlayer film 22.

[0019] The first transparent substrate 11 and the second transparent substrate 12 are preferably transparent substrates without birefringence. The thickness of the first transparent substrate 11 and the second transparent substrate 12 may be any thickness that maintains the durability of the substrate. The first transparent substrate 11 and the second transparent substrate 12 may be made of, for example, glass or transparent resin. The materials of the first transparent substrate 11 and the second transparent substrate 12 may be the same or different.

[0020] Soda-lime glass, alkali-free glass, borosilicate glass, aluminosilicate glass, etc. can be used as the glass constituting the first transparent substrate 11 and the second transparent substrate 12. The first transparent substrate 11 and the second transparent substrate 12 made of glass may be chemically strengthened, physically strengthened, or hard-coated, for example, to improve durability.

[0021] A cured product of a curable resin or a thermoplastic resin can be used as the transparent resin constituting the first transparent substrate 11 and the second transparent substrate 12, but a thermoplastic resin is preferred. Examples of the thermoplastic resin that can be used include polycarbonate, thermoplastic polyester (polyethylene terephthalate (hereinafter referred to as PET), polyethylene naphthalate, etc.), triacetyl cellulose, and cycloolefin polymer.

[0022] When the reflective transparent screen 101 is installed in a window of a vehicle, there is a possibility that a passenger may touch the reflective transparent screen 101. In addition, the window may be provided with a lifting mechanism. Since the image display layer 50 is protected between the first transparent substrate 11 and the second transparent substrate 12, high durability can be ensured even in such a case.

[0023] Polycarbonate resin, cycloolefin resin, cycloolefin copolymer resin, and polyester resin such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) can be used as the material of the resin film 43. It is preferable that the resin film 43 does not generate birefringence.

[0024] Thermoplastic resins, thermosetting resins, UV-curable resins, and the like can be used for the first interlayer film 21 and the second interlayer film 22. Examples of thermoplastic resins include polyvinyl acetal resins such as polyvinyl butyral resin (PVB), polyvinyl chloride resins, saturated polyester resins, polyurethane resins, ethylene-vinyl acetate copolymer resin (EVA), ethylene-ethyl acrylate copolymer resins, ionomer resins, and cycloolefin polymers (COP). The thermoplastic resin used for the interlayer film is selected based on the application, taking into account the balance of various properties such as transparency, weather resistance, strength, adhesive strength, penetration resistance, impact energy absorption, moisture resistance, heat insulation, and sound insulation. Considering the balance of these properties, PVB, EVA, and polyurethane resins are preferred as thermoplastic resins for the interlayer film. These thermoplastic resins may be used alone or in combination. The materials for the first interlayer film 21 and the second interlayer film 22 may be the same or different.

[0025] The image display layer 50 includes a concave-convex layer 51 , a reflective layer 52 and a cover layer 53 .

[0026] The uneven layer 51 is formed on the surface of the resin film 43. The uneven layer 51 is transparent and has irregular unevenness on the surface opposite to the resin film 43. A photocurable resin, a thermosetting resin, or a thermoplastic resin can be used as the uneven layer 51. Note that if the resin film 43 has irregular unevenness on the surface opposite to the first interlayer film 21, the uneven layer 51 does not necessarily have to be provided. In this case, the reflective layer 52, which will be described later, comes into contact with the resin film 43.

[0027] The reflective layer 52 is formed along the irregularities on the surface of the irregular layer 51. The reflective layer 52 can be made of a light-reflecting material, such as a metal such as aluminum or silver, a metal oxide, or a metal nitride. The reflective layer 52 functions as a half mirror. That is, the reflective layer 52 diffusely reflects part of the incident light and transmits the other part.

[0028] The covering layer 53 fills in the unevenness on the surface of the reflective layer 52. The covering layer 53 is formed of, for example, the same material as the uneven layer 51.

[0029] (Example of a reflective transparent screen) Fig. 4 is a cross-sectional view showing another example of a reflective transparent screen that can be used in this embodiment. The reflective transparent screen 102 shown in Fig. 4 is an example of the reflective transparent screen 100 shown in Fig. 1. The reflective transparent screen 102 corresponds to a transparent screen obtained by adding a light control function to the reflective transparent screen 101 shown in Fig. 3.

[0030] The reflective transparent screen 102 is formed by sandwiching a reflective image display layer 50, a resin film 43, and a light control film 80 between a first transparent substrate 11 and a second transparent substrate 12. Similar to the reflective transparent screen 101, a first intermediate film 21 is interposed between the resin film 43 and the first transparent substrate 11. A second intermediate film 22 is interposed between the image display layer 50 and the light control film 80.

[0031] Examples of light-controlling layers in light-controlling glass that can control visible light transmittance include suspended particle devices (SPDs), polymer-dispersed liquid crystals (PDLCs), polymer network liquid crystals (PNLCs), guest-host liquid crystals (GHLCs), electrochromic (EC) elements, photochromic (PC) elements, and electrokinetic (EK) elements.

[0032] The reflective transparent screen 102 shown in FIG. 4 uses a light-controlling film 80 having a structure in which a light-controlling layer 70 is sandwiched between transparent conductive films 61 and 62, such as ITO films. Below, an example using an SPD-type light-controlling layer 70 is shown, but this is not limited to this. SPD-type structures can easily accommodate curved surfaces. Furthermore, SPD-type structures have excellent resistance to high temperatures, which may be encountered during vehicle use. The light-controlling layer 70 is supported by insulating substrate films 41 and 42. The substrate films 41 and 42 are, for example, PET films. A third interlayer film 23 is interposed between the second transparent substrate 12 and the substrate film 42. The first interlayer film 21, the second interlayer film 22, and the third interlayer film 23 may be in contact with each other at the periphery of the reflective transparent screen 102. That is, at least one of the reflective image display layer 50 and the light-controlling film 80 may be located inside the interlayer film. Furthermore, the materials of the first intermediate film 21, the second intermediate film 22, and the third intermediate film 23 may be the same or different.

[0033] SPD particles 71 are dispersed within the light-controlling layer 70. In other words, in the light-controlling film 80, the light-controlling layer 70 made of a matrix resin containing SPD particles 71 is sandwiched between base films 41 and 42 coated with transparent conductive films 61 and 62.

[0034] When no voltage is applied to the transparent conductive films 61 and 62, the SPD particles 71 are not oriented. As a result, the visible light transmittance of the switchable layer 70 is low. When a voltage is applied to the transparent conductive films 61 and 62, the SPD particles 71 are oriented. As a result, the visible light transmittance of the switchable layer 70 increases, and the transparency increases. The visible light transmittance of the switchable layer 70 can be adjusted by changing the voltage value.

[0035] As an optical characteristic of the reflective transparent screens 101, 102 installed on the windows of a vehicle, for example, the visible light transmittance is preferably 5% or more and 90% or less. The visible light transmittance of the reflective transparent screens 101, 102 refers to the value when the visible light transmittance of the light control film 80 is high. If the visible light transmittance is within this range, the observer 700 can fully view the scenery outside the vehicle. The visible light transmittance is more preferably 10% or more, and even more preferably 20% or more. Furthermore, the visible light reflectance is preferably 5% or more and 70% or less. If the visible light reflectance is within this range, the observer 700 can fully view the image projected onto the reflective screen 100 by the projector 410.

[0036] In addition, in the reflective transparent screens 101 and 102, an anti-reflection film 11A may be provided on the vehicle interior surface, i.e., the projection surface (surface of the first transparent substrate 11) (see the dashed rectangle in Figures 3 and 4). The anti-reflection film may be, for example, a multilayer film in which multiple dielectric films are stacked, or a moth-eye structure in which the refractive index changes gradually. Furthermore, an anti-reflection film may also be provided on the vehicle exterior surface (surface of the second transparent substrate 12).

[0037] The specular reflectance of a typical transparent screen is about 8%, but an anti-reflection coating can reduce this by, for example, 2% or more (i.e., 6% or less). Reducing the specular reflectance of the reflective transparent screens 101, 102 makes reflected images less visible. The specular reflectance of the reflective transparent screens 101, 102 is preferably 2% or less, and more preferably 1% or less. If the specular reflectance of the transparent screen 10 exceeds 8%, the brightness of the reflected image reflected on the interior may increase, potentially causing annoyance. The specular reflectance and the diffuse reflectance, which will be described later, can be measured using a method that complies with condition c of JIS Z 8722:2009 "Methods for Measuring Color," for example, a spectrophotometer "CM-5" manufactured by Konica Minolta.

[0038] It should be noted that the transparent screen that can be used as the reflective transparent screen 100 in the image display system shown in Figure 1 is not limited to the reflective transparent screen 101 shown in Figure 3 or the reflective transparent screen 102 shown in Figure 4, and reflective transparent screens with other structures may also be used.

[0039] (Example of a transparent screen) 5 is a cross-sectional view showing an example of a transmission type transparent screen that can be used in this embodiment. The transmission type transparent screen 201 shown in FIG. 5 is an example of the transmission type transparent screen 200 shown in FIG.

[0040] The transmission type transparent screen 201 includes a first transparent substrate 11, a second transparent substrate 12, and a light scattering sheet (light scattering portion) 90. The first transparent substrate 11 and the light scattering sheet 90 are bonded together by a first bonding layer 44. The second transparent substrate 12 and the light scattering sheet 90 are bonded together by a second bonding layer 45.

[0041] When the transmission type transparent screen 201 is installed in a window of a vehicle, there is a possibility that a passenger may touch the transmission type transparent screen 201. Also, a lifting mechanism may be provided in the window of the vehicle. Even in these cases, the light scattering sheet 90 is protected between the first transparent substrate 11 and the second transparent substrate 12, so that high durability can be ensured.

[0042] The transmission type transparent screen 201 displays an image projected from a projector installed inside the vehicle so that it can be seen by an observer outside the vehicle.

[0043] The light-scattering sheet 90 has a first transparent film (first transparent layer) 94, a second transparent film (second transparent layer) 95, and a light-scattering layer 91. The light-scattering layer 91 is provided between the first transparent film 94 and the second transparent film 95. The first transparent film 94 and the second transparent film 95 serve as support members that support the light-scattering layer 91. The light-scattering layer 91 has, for example, a structure in which a light-scattering material 93 and a light-absorbing material (no reference number) are dispersed in a transparent resin 92.

[0044] The first transparent film 94 and the second transparent film 95 may be a resin film or a thin glass film. The material of the first transparent film 94 and the material of the second transparent film 95 may be the same or different. Examples of transparent resins that can be used to form the first transparent film 94 and the second transparent film 95 include polycarbonate, thermoplastic polyester, triacetyl cellulose, cycloolefin polymer, and polymethyl methacrylate.

[0045] The transparent resin 92 in the light-scattering layer 91 is preferably a cured product of a photocurable resin (such as a photocurable acrylic resin or a photocurable epoxy resin), a cured product of a thermosetting resin (such as a thermosetting acrylic resin or a thermosetting epoxy resin), or a thermoplastic resin (such as polycarbonate, thermoplastic polyester, triacetyl cellulose, cycloolefin polymer, or polymethyl methacrylate; other examples include polyolefin resin, thermoplastic polyimide resin, thermoplastic urethane, ionomer resin, ethylene-vinyl acetate copolymer (hereinafter, EVA), PVB, and thermoplastic silicone).

[0046] The light-scattering material 93 in the light-scattering layer 91 can be fine particles of a high-refractive-index material such as titanium oxide (refractive index: 2.5 to 2.7), zirconium oxide (refractive index: 2.4), aluminum oxide (refractive index: 1.76), zinc oxide (refractive index: 2.0), barium sulfate (refractive index: 1.64), or zinc sulfide (refractive index: 2.2). The light-scattering material 93 has a refractive index different from that of the transparent resin 92 that serves as the binder, and thus functions to scatter light. Since most resin materials have a refractive index of 1.45 to 1.65, it is preferable that the light-scattering material 93 differs in refractive index from these resin materials by 0.15 or more. Titanium oxide and zirconium oxide are particularly preferred as the light-scattering material 93 due to their high refractive index.

[0047] As light-absorbing materials, inorganic coloring materials such as carbon-based materials (carbon black, nanodiamond, fullerene, carbon nanotube, carbon nanohorn, graphene, etc.), titanium black, black silica, and particulate materials mainly containing silver (e.g., silver nitride, sulfide, and oxide) can be used.

[0048] The thickness of the light scattering layer 91 is preferably 1 μm to 200 μm. If the thickness of the light scattering layer 91 is 1 μm or more, the light scattering effect is sufficiently exhibited. If the thickness of the light scattering layer 91 is 200 μm or less, the light scattering layer 91 can be easily formed by a roll-to-roll process.

[0049] The light scattering layer 91 is not limited to the one shown in FIG.

[0050] Furthermore, as an optical characteristic of the transmission type transparent screen 201 to be installed on the window of a vehicle, for example, the visible light transmittance is preferably 5% or more and 90% or less. If the visible light transmittance is within this range, the observer 700 can sufficiently view the scenery outside the vehicle. The visible light transmittance is more preferably 10% or more, and even more preferably 20% or more.

[0051] It should be noted that the transparent screen that can be used as the transmissive transparent screen 200 in the image display system shown in FIG. 2 is not limited to the transmissive transparent screen 201 shown in FIG. 5, and transmissive transparent screens with other structures may also be used.

[0052] (Explanation regarding the embodiment) As described above, when an image is projected onto a transparent screen from the projector 410, a reflected image of the image formed on the transparent screen may be reflected onto the interior of the building. This problem can occur whether the transparent screen is the reflective transparent screen 100 (see FIG. 1) or the transmissive transparent screen 200 (see FIG. 2).

[0053] It has been discovered that the above problem (issue) can be solved by appropriately setting the relationship between the distance between the transparent screen and the projector 410, the distance between the projector 410 and the interior (the interior where a reflected image of the image formed on the transparent screen may be projected), the distance at which the projector 410 is in focus, and the focal depth of the projector 410.

[0054] First, the above relationship will be explained. FIG. 6 is a schematic diagram for explaining the above relationship. In FIG. 6, D indicates the distance between a projector 410, which is an example of a projection device, and a transparent screen (not shown in FIG. 6). This distance is defined as the distance between the point where the tip of the projection lens (objective lens) of the projector 410 intersects with the optical axis, and the point where the transparent screen intersects with the optical axis. Note that FIG. 6 shows the projection lens as a representative of the projector 410. Furthermore, when a mirror is installed outside the projection lens, this distance is defined as the distance (unit: mm) between the point where the mirror intersects with the optical axis and the point where the transparent screen intersects with the optical axis.

[0055] B indicates the distance between the transparent screen and the interior, which is defined as the distance (unit: mm) between the point where the transparent screen and the optical axis of the projector 410 intersect and the point on the interior where the optical axis enters after being specularly reflected by the transparent screen.

[0056] P indicates the distance (unit: mm) between the projector 410 and the position where the projector 410 is exactly in focus (so-called just-in-focus position). Hereinafter, this will also be simply referred to as the distance where the projector 410 is exactly in focus. If the distance P is unknown, it can be measured using a focus adjustment function used in various types of devices. As an example, Japanese Patent Application Laid-Open No. 2003-5020 describes a focus adjustment function for determining the position where the projector is in focus.

[0057] DOF indicates the depth of focus of the projector 410 (unit: mm).

[0058] As can be seen from the following examples and comparative examples, it has been confirmed that when formula 1 is satisfied, the image reflected on the interior is blurred, reducing the annoyance to vehicle occupants. The value on the left side of formula 1 can be used as an index correlated with the degree of blur of the image reflected on the interior. The value on the left side of formula 1 is preferably 410 or more, more preferably 425 or more, even more preferably 500 or more, even more preferably 700 or more, particularly preferably 800 or more, and most preferably 1000 or more. The upper limit of the value on the left side of formula 1 is, for example, 2000.

[0059] (D+B)-(P+DOF / 2)≧410...Equation 1

[0060] Hereinafter, D, B, P, and DOF will also be referred to as parameters.

[0061] The DOF is calculated using the following equation 2. In equation 2, NA represents the numerical aperture (unit: mm) of the objective lens, and λ represents the wavelength (unit: mm) of the projection light. For calculation, light with λ=0.000550 mm (550 nm) is generally used.

[0062] DOF=λ / NA 2 ...Formula 2

[0063] Moreover, it is desirable that D satisfy the following formula 3 in terms of image visibility. (P-DOF / 2)≦D≦(P+DOF / 2)...Equation 3

[0064] Other parameters used in the following examples and comparative examples are explained below. When the vehicle window (transparent screen) onto which the image is projected is flat, the incident angle of the projected light from projector 410 to the transparent screen is the angle between the normal to the plane and the optical axis of the projected light from projector 410. When the vehicle window is curved, the incident angle is the angle between the normal to the tangent plane of the curved surface and the optical axis of the projected light from projector 410.

[0065] In the following examples and comparative examples, the illuminance is measured by an illuminometer 600 placed in the interior at a position where the optical axis of light from projector 410 is incident after specular reflection from a transparent screen (a window of vehicle 400), as shown in FIG. 7. When the illuminance is measured, projector 410 is in an off state (a state in which no image is being projected). Then, with the illuminance inside the vehicle at 30 lux, reflections on the interior were evaluated using the parameter values ​​of the following examples and comparative examples.

[0066] When measuring the illuminance, a vehicle interior light or the like may illuminate an area wider than the area where the reflected image is projected by the transparent screen (see area 500 in FIG. 10). Also, in order to narrow the area where the reflected image is projected by the transparent screen, a projector 410 with a throw ratio of 1 or more may be used. [Example]

[0067] Examples will be described below together with comparative examples. Parameter values ​​and the like for each example and comparative example are shown in FIG.

[0068] As the transparent screen, a reflective transparent screen 101 shown in Fig. 3 or a reflective transparent screen 102 shown in Fig. 4 was used. The reflective transparent screens 101 and 102 used were as follows.

[0069] That is, glass having a thickness of 3 mm is used for the first transparent substrate 11 and the second transparent substrate 12. A UV-curable acrylic resin is used for the uneven layer 51 and the covering layer 53 in the image display layer 50. The material of the reflective layer 52 is aluminum. PVB having a thickness of 15 mil (approximately 0.38 mm) is used for the first interlayer film 21 and the second interlayer film 22.

[0070] In the following examples and comparative examples, "assessment of reflection" was carried out as follows. Figure 9 is an explanatory diagram for explaining the method of assessing reflection. As shown in Figure 9(A), Landolt rings (see Figure 9(B)) corresponding to visual acuity of 0.1, 0.2, 0.3, 0.4, and 0.5 were projected in order from a projector 410 installed inside a vehicle 400 onto a transparent screen 10 on the vehicle window.

[0071] If the observer 700 could not distinguish the gap in the Landolt ring corresponding to a visual acuity of 0.1 or 0.2 (the Landolt ring reflected in the interior), the "reflection assessment" was rated as good (i.e., the reflection was difficult to see). If the observer 700 could not distinguish the gap in the Landolt ring corresponding to a visual acuity of 0.3 or 0.4, the "reflection assessment" was rated as fair (i.e., the reflection was somewhat difficult to see). If the observer 700 could distinguish the gap in the Landolt ring corresponding to a visual acuity of 0.5, the "reflection assessment" was rated as poor (i.e., the reflection was easy to see).

[0072] (Example 1) D (the distance between the projector 410 and the transparent screen 10) was 814 mm, B (the distance between the transparent screen and the interior) was 1778 mm, P (the distance at which the projector 410 is perfectly focused) was 820 mm, and DOF (the depth of focus of the projector 410) was 722 mm. In this case, the value of the left side of the above equation 1 is 1411. In addition, the angle of incidence of the projected light from the projector 410 onto the transparent screen 10 was 40°. The luminous flux of the projector 410 was set to 3000 lm.

[0073] In Example 1, a reflective transparent screen 101 shown in Fig. 3 was used. That is, a transparent screen without a dimming function was used as the transparent screen 10. Furthermore, the reflective transparent screen 101 did not have an anti-reflection film 11A. An interior with a diffuse reflectance of 20% was used.

[0074] As shown in Figure 8, the results of the reflection assessment were good.

[0075] (Example 2) D was 424 mm, B was 1285 mm, P was 420 mm, and DOF was 500 mm. In this case, the value of the left side of the above formula 1 was 1039. In addition, the incident angle of the projected light from the projector 410 to the transparent screen 10 was 63°. The luminous flux of the projector 410 was set to 3000 lm.

[0076] In Example 2, the reflective transparent screen 101 shown in Fig. 3 was used, which did not have the anti-reflection film 11A. The interior had a diffuse reflectance of 20%.

[0077] As shown in Figure 8, the results of the reflection assessment were good.

[0078] (Comparative Example 1) D was 814 mm, B was 1778 mm, P was 820 mm, and DOF was 2888 mm. In this case, the value of the left side of the above equation 1 was 328. In addition, the incident angle of the projection light from the projector 410 to the transparent screen 10 was 40°. The luminous flux of the projector 410 was set to 3000 lm.

[0079] In Comparative Example 1, the reflective transparent screen 101 shown in Fig. 3 was used, which did not have the anti-reflection film 11A. The interior had a diffuse reflectance of 20%.

[0080] As shown in FIG. 8, the result of the evaluation of the reflection was poor.

[0081] (Example 3) D was 814 mm, B was 1778 mm, P was 820 mm, and DOF was 722 mm. In this case, the value of the left side of the above formula 1 is 1411. In addition, the incident angle of the projection light from the projector 410 to the transparent screen 10 was 40°. The luminous flux of the projector 410 was set to 3000 lm.

[0082] In Example 3, the reflective transparent screen 101 shown in Fig. 3 was used, which did not have the anti-reflection film 11A. The interior had a diffuse reflectance of 90%.

[0083] As shown in Figure 8, the result of the reflection assessment was normal. Comparing Example 1 and Example 2 with Example 3, the result of the reflection assessment was slightly worse when the interior diffuse reflectance was high. However, since the result of the reflection assessment was normal, it can be seen that even if the interior diffuse reflectance was 90%, the result of the reflection assessment would not be poor.

[0084] (Example 4) D was 814 mm, B was 1778 mm, P was 820 mm, and DOF was 2000 mm. In this case, the value of the left side of the above formula 1 was 772. In addition, the incident angle of the projection light from the projector 410 to the transparent screen 10 was 40°. The luminous flux of the projector 410 was set to 3000 lm.

[0085] In Example 4, the reflective transparent screen 101 shown in Figure 3 was used, but did not have the anti-reflection film 11A. Note that an interior lining (for example, a non-reflective sheet) with a diffuse reflectance of 0.5% was used.

[0086] The results of the evaluation of reflection were good, as shown in Figure 8. In Example 4, the DOF value was relatively large compared to the other examples, but the results of the evaluation of reflection were good by using an interior with low diffuse reflectance.

[0087] (Example 5) D was 814 mm, B was 1778 mm, P was 820 mm, and DOF was 722 mm. In this case, the value of the left side of the above formula 1 is 1411. In addition, the incident angle of the projection light from the projector 410 to the transparent screen 10 was 40°. The luminous flux of the projector 410 was set to 3000 lm.

[0088] In Example 5, the reflective transparent screen 101 shown in Fig. 3 was used, which had an anti-reflection film 11A. The interior had a diffuse reflectance of 90%.

[0089] As shown in Figure 8, the results of the reflection assessment were good. The parameter values ​​used in Example 5 were the same as those used in Example 3. As can be seen from a comparison with the results of the reflection assessment in Example 3, when the specular reflectance of the transparent screen 10 is reduced by the anti-reflection coating (for example, when the specular reflectance is reduced to 0.1%), the results of the reflection assessment are better.

[0090] (Example 6) D was 814 mm, B was 1778 mm, P was 820 mm, and DOF was 722 mm. In this case, the value of the left side of the above formula 1 is 1411. In addition, the incident angle of the projection light from the projector 410 to the transparent screen 10 was 40°. The luminous flux of the projector 410 was set to 300 lm.

[0091] In Example 6, the reflective transparent screen 102 shown in Fig. 4 was used. That is, a transparent screen having a dimming function was used as the transparent screen 10. The reflective transparent screen 102 did not have an anti-reflection film 11A. The interior had a diffuse reflectance of 90%.

[0092] As shown in FIG. 8, the results of the reflection assessment were good. That is, when a transparent screen with a dimming function is used, the results of the reflection assessment are good even if the luminous flux of projector 410 is small. That is, even if the luminous flux of projector 410 is small, the image reflected on the interior is difficult to see by cutting off external light, so the results of the reflection assessment are good. In addition, the parameter values ​​used in Example 6 are the same as the parameter values ​​used in Example 3. As can be seen from a comparison with the results of the reflection assessment in Example 3, by using a transparent screen with a dimming function, the results of the reflection assessment are better even if the diffuse reflectance of the interior is high.

[0093] (Comparative Example 2) D was 1550 mm, B was 400 mm, P was 1550 mm, and DOF was 1050 mm. In this case, the value of the left side of the above equation 1 was -125. In addition, the incident angle of the projection light from the projector 410 to the transparent screen 10 was 28°. The luminous flux of the projector 410 was set to 3000 lm.

[0094] In Comparative Example 2, the reflective transparent screen 101 shown in Fig. 3 was used, which did not have the anti-reflection film 11A. The interior had a diffuse reflectance of 20%.

[0095] As shown in FIG. 8, the result of the evaluation of the reflection was poor.

[0096] (Example 7) D was 1200 mm, B was 1100 mm, P was 1100 mm, and DOF was 722 mm. In this case, the value of the left side of the above equation 1 is 839. In addition, the incident angle of the projection light from the projector 410 to the transparent screen 10 was 38°. The luminous flux of the projector 410 was set to 3000 lm.

[0097] In Example 7, the reflective transparent screen 101 shown in Fig. 3 was used, but did not have the anti-reflection film 11A. The interior had a diffuse reflectance of 50%.

[0098] As shown in Figure 8, the results of the reflection assessment were good.

[0099] (Example 8) D was 1450 mm, B was 600 mm, P was 1480 mm, and DOF was 200 mm. In this case, the value of the left side of the above formula 1 was 470. In addition, the incident angle of the projection light from the projector 410 to the transparent screen 10 was 28°. The luminous flux of the projector 410 was set to 3000 lm.

[0100] In Example 8, the reflective transparent screen 101 shown in Figure 3 was used, but did not have the anti-reflection film 11A. The interior had a diffuse reflectance of 20%.

[0101] As shown in Figure 8, the results of the reflection assessment were average.

[0102] (Comparative Example 3) D was 1120 mm, B was 480 mm, P was 1120 mm, and DOF was 150 mm. In this case, the value of the left side of the above equation 1 was 405. In addition, the incident angle of the projection light from the projector 410 to the transparent screen 10 was 75°. The luminous flux of the projector 410 was set to 3000 lm.

[0103] In Comparative Example 3, the reflective transparent screen 101 shown in Fig. 3 was used, which did not have the anti-reflection film 11A. The interior had a diffuse reflectance of 20%.

[0104] As shown in FIG. 8, the result of the evaluation of the reflection was poor.

[0105] Since the results of the evaluation of reflection were poor in Comparative Example 1 where the value of the left side of Equation 1 was 328, Comparative Example 2 where it was -125, and Comparative Example 3 where it was 405, favorable results can be obtained when Equation 1 is satisfied (when the left side of Equation 1 is approximately 410 mm or more). That is, it is possible to make it difficult to see the image of the image formed on the transparent screen 10 reflected on the interior. Furthermore, from the value of the left side of Equation 1 in Example 4, favorable results can be obtained when the value of the left side of Equation 1 is 700 or 800. Furthermore, from the values ​​of the left side of Equation 1 in Examples 1 to 2 and Examples 4 to 6, favorable results can be obtained when the value of the left side of Equation 1 is 1400 or 1500.

[0106] Furthermore, taking into consideration the internal environment (size, etc.) of the vehicle in which the transparent screen 10 is installed and the specifications of a typical projector, the upper limit of the left side of Equation 1 (the upper limit of the range in which the reflection assessment result is not poor) can be said to be approximately 2000 mm.

[0107] From the above, it is determined that the preferable range of the value of the left side of Equation 1 is approximately 410 or more and 2000 or less, as shown in FIG.

[0108] In Example 2, where Equation 1 is satisfied, D is 424 mm. In Example 2, favorable results can be obtained. In Examples 1, 3, and 6, where the result of the reflection assessment is good or average, D is 814 mm. In Example 7, where the result of the reflection assessment is good, D is 1200 mm, and in Example 8, where the result is average, D is 1450 mm. Taking these factors into consideration, when Equation 1 is satisfied, a favorable range for D is determined to be approximately 200 mm or more and 1500 mm or less, as shown in FIG. 8. If D is 200 mm or more, the projector 410 can project an image of a sufficient size onto the transparent screen 10 mounted on the vehicle. Furthermore, if D is 1500 mm or less, the distance from the projector 410 to the transparent screen 10 is not excessively long, which makes it easier to prevent shadows from being cast on the image projected on the transparent screen 10 due to interference with the optical path by mounted objects inside the vehicle or the heads of occupants.

[0109] In Examples 1 to 6, where the result of the reflection assessment is good or average, B is 1285 mm or 1778 mm. In Example 7, where the result of the reflection assessment is good, B is 1100 mm, and in Example 8, where the result is average, B is 600 mm. Taking these factors into consideration, when Expression 1 is satisfied, it is determined that the preferable range for B is approximately 500 mm or more and 2500 mm or less, as shown in FIG. 8. If B is 500 mm or more, it is easy to ensure space inside the vehicle that allows an observer to enter. Furthermore, if B is 2500 mm or less, it is easy to make the vehicle width a size suitable for driving on public roads.

[0110] In Example 2, where Equation 1 is satisfied, P is 420 mm. In Example 2, favorable results can be obtained. In Examples 1 and 3 to 6, where the result of the reflection assessment is good or average, P is 820 mm. In Example 7, where the result of the reflection assessment is good, P is 1100 mm, and in Example 8, where the result is average, P is 1480 mm. Taking these factors into consideration, when Equation 1 is satisfied, the favorable range for P is determined to be approximately 200 mm or more and 1500 mm or less, as shown in FIG. 8. If P is 200 mm or more, focusing difficulties due to constraints of the optical system of projector 410 (such as the refractive index of the lens) are unlikely to occur. Furthermore, if P is 1500 mm or less, it is unlikely to be restricted by the size of the vehicle, and therefore it is easy to prevent the image projected on screen 10 from becoming blurred due to the image being focused at a position shifted from screen 10.

[0111] As can be seen from Example 2, when Equation 1 is satisfied, favorable results are obtained even if the incident angle is large (specifically, 63°). Therefore, as shown in FIG. 8, it was confirmed that the upper limit of the incident angle is approximately 70°. Furthermore, from Examples 1 and 3 to 8, it is preferable that the incident angle is approximately 20° or greater. If the incident angle is 70° or less, the light projected from projector 410 is less likely to be totally reflected by the vehicle's inner surface of screen 10, the amount of light reaching image display layer 50 of screen 10 is less likely to be reduced, and the brightness of the projected image is less likely to decrease. Furthermore, if the incident angle is 20° or greater, the observer 700 is less likely to experience glare when looking directly at the light projected from projector 410 onto screen 10 and specularly reflected by the vehicle's inner surface.

[0112] Furthermore, based on the luminous flux of the projector 410 in Examples 1 to 8, it is determined that a preferable range of the luminous flux of the projector 410 is approximately 100 lm or more and 10,000 lm or less, as shown in Fig. 8. If the luminous flux is 100 lm or more, it is easy to ensure the visibility of the image projected on the transparent screen 10. Furthermore, if the luminous flux is 1,000 lm or less, it is easy to ensure the comfort of the passengers, as the exhaust heat and noise from the projector 410 are less likely to affect driving.

[0113] As mentioned above, favorable results can be obtained when the specular reflectance of the transparent screen 10 is set to 0.1% using an anti-reflection coating, but even if the specular reflectance of the transparent screen 10 is around 8%, that is, even if the specular reflectance is not reduced, the result of the glare assessment is good or average. Therefore, the preferable range of specular reflectance of the transparent screen 10 on the inside of a vehicle can be said to be 0.1% or more and 8% or less, as shown in Figure 8.

[0114] In addition, in Examples 1 to 8, where the reflection assessment result was good or average, the interior diffuse reflectance was 20%. In Examples 3 to 6, where the reflection assessment result was good or average, the interior diffuse reflectance was 0.5% or 90%. In Example 7, where the reflection assessment result was good, the interior diffuse reflectance was 50%. Therefore, as shown in Figure 8, the preferable range of the interior diffuse reflectance is determined to be approximately 0.1% to 90%. If the interior diffuse reflectance is 0.1% or higher, the absorption rate in the near-infrared region is unlikely to increase, and the temperature inside the vehicle is unlikely to rise. Furthermore, if the interior diffuse reflectance is 90% or lower, the brightness of the reflected image reflected on the interior is suppressed, making it less likely to be annoying. It is more preferable that the interior diffuse reflectance be 50% or lower.

[0115] In the above examples, the reflective transparent screen 101 shown in FIG. 3 or the reflective transparent screen 102 shown in FIG. 4 was used as the transparent screen 10, but the results shown in FIG. 8 can also be obtained when the transmissive transparent screen 201 shown in FIG. 5 is used. [Explanation of symbols]

[0116] 10 Transparent Screen 11 First transparent substrate 11A Anti-reflection coating 12 Second transparent substrate 21 First interlayer 22 Second interlayer 23 Third Interlayer 41,42 Base film 43 Resin film 44 First bonding layer 45 Second bonding layer 50 Image display layer 51 Uneven layer 52 Reflective layer 53 Covering layer 61,62 Transparent conductive film 70 Photochromic Layer 71 SPD particles 80 Light Control Film 90 Light scattering sheet 91 Light scattering layer 92 transparent resin 93 Light scattering materials 94 First Transparent Film 95 Second Transparent Film 100,101,102 Reflective transparent screen 200,201 Transparent screen 400 vehicles 410 Projector

Claims

1. a projection device disposed inside the vehicle and configured to project an image; a transparent screen on which the image projected from the projection device is displayed so as to be visible to an observer inside or outside the vehicle, A video display system that satisfies the following formula 1. (D+B)-(P+DOF / 2)≧410...Formula 1 In Equation 1, D represents the distance [mm] between the projection device and the transparent screen, B represents the distance [mm] between the transparent screen and the interior material of the vehicle, P represents the distance [mm] at which the projection device is exactly in focus, and DOF represents the depth of focus [mm] of the projection device.

2. The upper limit of the value on the left side of Equation 1 is 2000. The video display system according to claim 1 .

3. D is 200 mm or more and 1500 mm or less 3. The video display system according to claim 1.

4. B is 500 mm or more and 2500 mm or less 3. The video display system according to claim 1.

5. P is 200 mm or more and 1500 mm or less 3. The video display system according to claim 1.

6. The incident angle of the light from the projection device to the transparent screen is between 30° and 70°.

3. The video display system according to claim 1.

7. The specular reflectance of the transparent screen on the surface inside the vehicle is 0.1% or more and 8% or less.

3. The video display system according to claim 1.

8. The transparent screen is a reflective transparent screen.

3. The video display system according to claim 1.

9. The reflective transparent screen is an image display layer including a concave-convex layer having a concave-convex surface, a reflective layer formed along the concave-convex surface of the concave-convex layer, and a covering layer filling in the concave-convex surface of the reflective layer; a support member for supporting the image display layer; 9. The video display system according to claim 8.

10. The reflective transparent screen includes a light control film capable of controlling visible light transmittance.

9. The video display system according to claim 8.

11. The transparent screen is a transparent screen.

3. The video display system according to claim 1.

12. The transmission type transparent screen includes a light scattering section including a first transparent layer, a second transparent layer, and a light scattering layer formed between the first transparent layer and the second transparent layer; a support member for supporting the light scattering portion; The video display system according to claim 11.

13. The video display system according to claim 1 or 2 is installed, The transparent screen is installed in the window. vehicle.

14. The diffuse reflectance of the interior material is 0.1% or more and 90% or less.

14. The vehicle of claim 13.

Images