JP2021177252A - Screen and video display system - Google Patents

Abstract

To provide a screen and a video display system that can display with bright and high sharpness on a total surface of the screen in a projection state suitable for video projection on a transparent screen.SOLUTION: A screen being the screen having reflectivity that injects video projected from a projector with an incident angle of 75deg, and that diffusely reflects the video in a normal direction of a surface, and transparency that transmits a background comprises: a rugged sheet; a semi-transmissive reflective layer; and a transparent layer. The rugged sheet is made of a transparent material, and one main surface is a flat surface, and the other main surface is a rugged shape surface on which a plurality of recessed portions and protrusion portions are formed. The reflective layer is formed on the rugged shape surface of the rugged sheet. The transparent layer covers the reflective layer. Concerning an inclination angle of the rugged shape surface, a distribution rate, in which the inclination angle is 18deg, is more than or equal to 2.0%/deg, the distribution rate, in which the inclination angle is 25deg, is more than or equal to 0.3%/deg, and a ratio, in which the distribution rate being more than or equal to the inclination angle 40deg occupies, is less than or equal to 20%.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a screen and an image display system having a reflectivity for diffuse-reflecting an image projected from a projector and a transparency for transmitting an image through a background.

In recent years, a transparent screen has been proposed that displays an image by diffuse-reflecting an image projected from a projector while having transparency that allows the background to pass through. For example, in a video display system equipped with a transparent screen, a transparent screen is installed in the window of a high-rise building to superimpose the night view and the video, or to produce the video as if it were displayed in the air at a live event or the like. .. In this way, a transparent screen is expected as a key device that realizes a new image expression by a projector.

As the image projection method by the projector, there are a rear projection method in which an image is projected from the back of the screen and the image is displayed as a transmitted image, and a front projection method in which the image is projected from the front of the screen and the image is displayed as a reflected image. The screen for the rear projection method is called a transmissive screen, and the screen for the front projection method is called a reflective screen. Then, a transparent screen that allows the background to pass through can be used for both the transmissive screen and the reflective screen.

As an example of the transparent screen, a transmissive transparent screen having a structure including a scattering layer has been proposed (Patent Documents 1 and 2). This scattering layer is formed by slightly dispersing special diffused fine particles inside the transparent body. In the transmissive transparent screen having this configuration, the image projected from the projector is largely diffused by the scattering layer to display the image, and the background is transmitted straight through. Further, in the transmissive transparent screen having this configuration, a part of the light diffused by the scattering layer is reflected at the interface between the back surface of the transmissive transparent screen and air. Therefore, the transmissive transparent screen can also display an image as a reflected image like a screen for a front projection method. For this reason, the transmissive transparent screen is sometimes applied to windows of commercial facilities as a reflective transparent screen.

Further, as a reflective transparent screen, a semitransparent reflective layer that reflects a part of light and transmits or absorbs another is provided on a plurality of convex portions, and the surface of the semitransparent reflective layer is coated with a transparent material. (Patent Document 3). This screen can display the projected light as an image and allows a part of the light to pass straight through, so that the background can be seen through.

Japanese Unexamined Patent Publication No. 2011-113068 Japanese Unexamined Patent Publication No. 2015-212800 International Publication No. 2015/186668

The present disclosure provides a screen and an image display system capable of displaying a bright and highly sharp image over the entire screen in a projection state suitable for projecting an image on a transparent screen.

The screen according to the present disclosure is a screen having a reflectivity of incident an image projected from a projector at an incident angle of 75 deg and diffusely reflecting the image in the normal direction of the surface and a transparency of transmitting the background. A concavo-convex sheet, a semi-transparent reflective layer, and a transparent layer are provided. The concavo-convex sheet is made of a transparent material, and one main surface is a flat surface, and the other main surface is an concavo-convex surface on which a plurality of concave portions and convex portions are formed. The reflective layer is formed on the uneven surface of the concave-convex sheet. The transparent layer covers the reflective layer. The inclination angle formed by the tangent line at the point where the light of the image is reflected on the uneven surface and the main surface of the uneven surface has a distribution ratio of 2.0% / deg or more when the inclination angle is 18 deg, and The distribution rate at 25 deg is 0.3% / deg or more.

The screen and image display system in the present disclosure can display a transparent screen with a bright and high sharpness over the entire screen.

It is a conceptual diagram for demonstrating the image display system in Embodiment 1. FIG. It is a conceptual diagram for demonstrating the cross-sectional structure of the screen in Embodiment 1. FIG. It is a figure which shows the condition of the inclination angle of the concave-convex-shaped surface for reflecting the light incident from diagonally below in the normal direction with respect to the screen surface. It is a figure which shows the relationship between the incident angle of light, and the inclination angle of an uneven surface. It is a figure which shows the histogram of the abundance rate of the inclination angle of the surface of an uneven shape in embodiment. It is a figure which shows the distribution rate of the inclination angle of the surface of a concavo-convex shape in an embodiment. It is a figure which shows the histogram of the abundance rate of the inclination angle of the surface of an uneven shape in embodiment. It is a figure which shows the distribution rate of the inclination angle of the surface of a concavo-convex shape in an embodiment. It is a figure which shows the micrograph of the surface of the concavo-convex shape in Example 2. FIG. It is a figure which shows the distribution rate of the inclination angle of the surface of an uneven shape in an Example and a comparative example. It is a figure which shows the transmission and reflection characteristics of a screen in an Example and a comparative example. It is a figure which shows the haze characteristic of the screen in an Example and a comparative example. It is a figure which shows the front gain characteristic of the screen in an Example and a comparative example. It is a conceptual diagram for demonstrating a conventional video display system.

(Background to this disclosure)
The background of the process leading to the present invention will be described with reference to the drawings. FIG. 14 is a conceptual diagram showing a typical arrangement example when a general reflective screen without see-through background is used. FIG. 1 is a conceptual diagram showing a typical arrangement example of a conventional video display system using a screen capable of seeing through the background.

In projection using a reflective screen in a conference room or movie theater as shown in FIG. 14, the long focus projector installed on the ceiling or desk is relatively shallow in the range of 0 ± 20 deg with respect to the vertical direction of the reflective screen. Project at an angle. By projecting the image in this arrangement, the observer can obtain a good viewing environment without blocking the projected light.

If the same arrangement as in FIG. 14 is used on a screen capable of seeing through the background, a failure occurs due to the following reasons. In a screen capable of seeing through the background, the transmitted light needs to be transmitted straight ahead without being scattered in order to ensure the visibility of the background. Therefore, the surface of the screen that can see through the background needs to be flat. Then, in the case of the arrangement of FIG. 14, the flat surface causes specular reflection, and the image cannot be visually recognized at the hot spot where the specular reflected light of the projected light directly enters the observer's eyes.

In order to prevent hot spots, it is necessary to project the specularly reflected light at a large angle so that it does not enter the observer's eyes in the assumed viewing range on the screen where the background can be visually recognized. At this time, in order to project from a limited space such as the floor or the ceiling, a long-focus projector is used to project at a large angle. That is, as shown in FIG. 1, it is practical to project from the floor or ceiling near the screen by the projector 30. Light is incident on the screen 10 whose background is visible at a relatively large angle and at various different angles depending on the location. The range of the incident angle of the light varies depending on the projector 30, but it is about 60 deg at the center of the screen, about 30 deg at the lower end, about 70 deg at the upper end, and about 25 deg to 75 deg.

Therefore, the screen 10 is required to have a diffuse reflection characteristic of diffuse reflection in the observer direction so that the projected light incident at an angle of 25 deg to 75 can be visually recognized as an image.

However, Patent Document 3 does not disclose a configuration for realizing such a reflection characteristic.

As a result of various studies, we made a screen in which the background can be visually recognized by appropriately setting the inclination angle distribution of the uneven shape as a configuration in which the image is diffused by the semitransparent reflective layer formed on the uneven surface. It has been found that diffuse reflection characteristics that enable good image observation can be realized under suitable projection conditions. As a result, it is possible to realize a screen that can be displayed brightly on the entire surface without causing hot spots due to specular reflection on the screen surface.

Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanations of already well-known matters and duplicate explanations for substantially the same configuration may be omitted. This is to avoid unnecessary redundancy of the following description and to facilitate the understanding of those skilled in the art.

It should be noted that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

Hereinafter, embodiments will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a conceptual diagram for explaining the video display system according to the first embodiment. As shown in FIG. 1, the image display system includes a screen 10 and a projector 30. The screen 10 is a reflective transparent screen, which is installed in the window 20 of the building and displays an image projected from the projector 30. The screen 10 also allows the background outside the window 20 to pass through. That is, the person 40 in front of the screen 10 can simultaneously observe the background outside the window 20 and the image projected from the projector 30 on the screen 10.

The screen 10 is a screen having transparency that diffuses and reflects the image projected from the projector 30 and transparency that allows the background to pass through. The screen 10 diffusely reflects a part of the incident visible light (5% to 50%) and transmits the remaining part of the visible light (30% or more) in a straight line. By setting the diffuse reflection and the straight-line transmission to the above ratios, the person 40 can observe the image and the background on the screen 10 in a well-balanced manner. When the image is not projected from the projector 30, the screen 10 functions as a transparent body, so that the person 40 can observe the background as in the case without the screen 10. On the other hand, when an image is projected from the projector 30, the screen 10 diffusely reflects a part of the projected image, so that the person 40 can observe the projected image and also observe the background. can.

The light transmitted through the screen 10 needs to travel straight so that the person 40 can clearly observe the background. Therefore, the surface of the screen 10 which is the interface with air needs to be flat. Since the surface of the screen 10 is flat, the reflection on the surface of the screen 10 is specular. When the specularly reflected light of the image projected from the projector 30 enters the eyes of the person 40 directly, the person 40 is dazzling and cannot observe the image. Therefore, as shown in FIG. 1, the projector 30 projects an image at a large incident angle with respect to the screen 10 so that the specularly reflected light does not face the person 40 located in the front direction of the screen 10. Further, the projector 30 projects an image near the screen 10 with an inclination angle from diagonally below so that the image projected from the projector 30 is not blocked by the person 40. Therefore, as the projector 30, an ultra-short throw projector having a short focal length is used. At this time, the incident angle of the light incident on the screen 10 is about 65 deg at the center of the screen 10, about 75 deg at the left and right edges of the upper part of the screen, and about 25 deg at the center of the lower part of the screen. Here, the incident angle of light means the angle formed by the direction of the incident light and the normal direction with respect to the surface of the screen 10.

The visibility of the image displayed on the screen 10 changes depending on the situation such as the brightness of the background. When the background is bright, such as in the daytime, the background is brighter than the image, so that it is difficult for the screen 10 to display the image with high contrast. Therefore, when the background is bright, the screen 10 is mainly used for displaying information and the like. On the other hand, when the background is dim, such as in the evening, the screen 10 can display an image with high contrast, and a fantastic effect can be produced by superimposing the image and the background. Further, when the background is sufficiently dark such as at night, the screen 10 can display an image with high contrast like a normal display device.

FIG. 2 is a conceptual diagram for explaining the cross-sectional configuration of the screen 10 according to the first embodiment. As shown in FIG. 2, the screen 10 includes a concavo-convex sheet 11, a semi-transparent reflective layer 14, and an adhesive layer 15. The concavo-convex sheet 11 is made of a transparent material, and one main surface is a flat surface, and the other main surface is an concavo-convex surface on which a plurality of concave portions and convex portions are formed. The reflective layer 14 is formed on the uneven surface of the concave-convex sheet 11. The adhesive layer 15 is a transparent layer that covers the reflective layer 14.

The concavo-convex sheet 11 is composed of a base material sheet 12 and a transparent concavo-convex layer 13. The base sheet 12 is made of a transparent material such as PET (polyethylene terephthalate) having a flat surface, and has a thickness of 50 μm to 100 μm. The concavo-convex layer 13 is formed on the surface of the base sheet 12 by an ultraviolet curable resin so that the surface of the concavo-convex layer 13 has an concavo-convex shape. The uneven shape of the uneven layer 13 determines the diffusion characteristics of the screen 10. Since the concavo-convex sheet 11 is configured in this way, the surface on which the light is incident can be formed to be flat, and the surface on which the light is diffusely reflected can be formed to have an concavo-convex shape.

The reflective layer 14 is formed on the surface side of the concave-convex shape of the concave-convex sheet 11 and is made of a thin film having a thickness of 2 nm to 1 μm. With this configuration, a part of the light incident on the screen 10 can be reflected and a part can be transmitted. In particular, a screen having a transmittance of 30% or more for visible light and a diffuse reflectance of 5% to 50% for visible light can be realized. As a result, the person 40 can observe the image and the background on the screen 10 in a well-balanced manner.

The reflective layer 14 is, for example, a thin film having a thickness of 2 nm to 50 nm. The thin film is made of any metal of nickel (Ni), aluminum (Al), silver (Ag), and chromium (Cr), or an alloy containing any of nickel, aluminum, silver, and chromium as a main component. With this configuration, the reflective layer 14 can be formed by a simple process of forming one thin film.

Further, the reflective layer 14 may be a dielectric multilayer film having a thickness of 0.5 μm to 1 μm. The dielectric multilayer film is composed of a plurality of layers of a transparent dielectric material having a high refractive index (n = 2.0 to 3.0) and a transparent dielectric material having a low refractive index (n = 1.0 to 1.9) alternately. It is a laminated product. The dielectric multilayer film can achieve desired reflection characteristics and transmission characteristics by adjusting the refractive index of the material and the thickness of the dielectric multilayer film. Further, with this configuration, it is possible to reduce the absorption of light incident on the screen 10 as compared with the case where the reflective layer 14 is composed of a thin film of metal or a thin film of alloy. As a result, the screen 10 can display an image with high brightness and can transmit the background with high brightness.

The adhesive layer 15 is made of a transparent adhesive such as an acrylic layer that covers the reflective layer 14. The refractive index of the adhesive layer 15 is substantially the same as the refractive index of the uneven sheet 11, and is about 1.5. Since the adhesive layer 15 is formed on the back surface of the screen 10, the screen 10 can be attached to the window 20.

As shown in FIG. 2, a part of the light projected from the projector 30 and incident on the screen 10 from diagonally below is diffusely reflected in the normal direction with respect to the surface of the screen 10 and observed by the person 40 as an image.

Next, with reference to FIG. 3, the condition of the inclination angle θ3 of the concave-convex-shaped surface of the concave-convex sheet 11 when the light incident from diagonally below is reflected in the normal direction with respect to the surface of the screen 10 will be described. Here, the inclination angle θ3 is an angle formed by a flat surface of the concavo-convex sheet 11 and a tangent line at a point where light is reflected on the concavo-convex surface of the concavo-convex sheet 11. Since the base sheet 12 and the uneven layer 13 are both made of a transparent material having substantially the same refractive index, they are optically homogeneous. Therefore, in FIG. 3, the base sheet 12 and the concavo-convex layer 13 are integrated and displayed as the concavo-convex sheet 11.

Light incident at an incident angle θ1 from the flat surface side of the concavo-convex sheet 11 made of a transparent material having a refractive index n is refracted to the angle θ2 obtained by Equation 1 according to Snell's law, and travels in the concavo-convex sheet 11.

(Formula 1)
θ2 = sin-1 {sin (θ1) / n}
The condition for the light traveling in the concavo-convex sheet 11 to be reflected by the reflective layer 14 in the normal direction with respect to the surface of the screen 10 is that the inclination angle θ3 of the concavo-convex surface is half of the angle θ2. That is, the inclination angle θ3 of the uneven surface for reflecting in the normal direction with respect to the surface of the screen 10 can be obtained by the mathematical formula 2.

(Formula 2)
θ3 = sin-1 {sin (θ1) / n} / 2
Next, using FIG. 4, when the refractive index n of the concave-convex sheet 11 is 1.5, which is the general refractive index of the transparent resin material, the incident angle θ1 and the light incident at the incident angle θ1 are reflected. The relationship between the layer 14 and the uneven surface inclination angle θ3 required for reflection in the normal direction with respect to the surface of the screen 10 will be described.

As described above, the incident angle θ1 of the light incident on the screen 10 is 75 deg at the maximum. As shown in FIG. 4, the inclination angle θ3 of the uneven surface for reflecting the light incident at an incident angle of 75 deg in the normal direction with respect to the surface of the screen 10 is 20 deg. Further, in order for the person 40 to observe the image from various angles, it is necessary to diffuse the image within a range of at least ± 15 deg from the normal direction with respect to the surface of the screen 10. The range of the inclination angle θ3 required to emit the reflected light into the range of ± 15 deg from the normal direction of the uneven sheet 11 is about ± 5 deg. Therefore, when the incident angle θ1 is 75 deg at the maximum, the inclination angle θ3 for diffusing the image in the range of ± 15 deg from the normal direction with respect to the screen 10 surface is about 20 ± 5 deg. That is, the inclination angle θ3 of the concave-convex-shaped surface of the concave-convex sheet 11 needs to have a distribution of up to 25 deg.

Further, the light reflected by the reflective layer 14 having an inclination angle θ3 larger than 40 deg is totally reflected at the interface between the concave-convex sheet 11 and the air and returned to the inside of the concave-convex sheet 11. Therefore, the presence of an inclination angle θ3 of 40 deg or more rather lowers the reflection efficiency of the screen 10. Therefore, it is desirable that the inclination angle θ3 is appropriately distributed in the range of 0 deg to 40 deg.

Hereinafter, the quantification of the inclination angle distribution of the uneven surface will be described with reference to FIGS. 5 to 8.

5 and 7 are diagrams showing a histogram of the abundance rate of the inclination angle θ3 of the concave-convex-shaped surface of the concave-convex sheet 11. The histograms shown in FIGS. 5 and 7 are created by measuring the inclination angle distribution of the uneven surface with a three-dimensional measuring device or a laser microscope and using the inclination angle distribution. Further, the histograms shown in FIGS. 5 and 7 are both created from the same inclination angle distribution. In FIGS. 5 and 7, the horizontal axis indicates the range of the inclination angle θ3 of the concave-convex-shaped surface, and the vertical axis represents the ratio of the inclination angle of the uneven-shaped surface belonging to the range of the inclination angle indicated by the horizontal axis as the abundance rate. Shown. On the horizontal axis, in FIG. 5, the inclination angle is decomposed and displayed in an angle range of 5 deg, whereas in FIG. 7, the inclination angle is decomposed and displayed in an angle range of 10 deg. Therefore, the profile on the vertical axis of FIG. 7 is twice as large as the profile on the vertical axis of FIG.

On the other hand, FIGS. 6 and 8 are views showing the distribution ratio of the inclination angle of the concave-convex-shaped surface of the concave-convex sheet 11. Each of FIGS. 6 and 8 is created from each of FIGS. 5 and 7, respectively. In FIGS. 6 and 8, the horizontal axis indicates the median value of the range of each inclination angle indicated by each of the horizontal axes of FIGS. 5 and 7, and the vertical axis indicates the abundance indicated by the range of each inclination angle. The value divided by is shown. An example will be described with reference to FIGS. 5 and 6. In FIG. 5, the abundance rate indicated by the range of the inclination angle θ3 from 20 deg to 25 deg is 20%. Therefore, in FIG. 6, the horizontal axis shows the median value of 20 deg to 25 deg, which is 22.5 deg, and the corresponding vertical axis shows the value obtained by dividing the abundance rate of 20% by 5 deg, which is the range of the inclination angle θ3. It shows% / deg. By displaying in this way, it is possible to quantify the inclination angle distribution regardless of the method of decomposing the angle range of the inclination angle. That is, the vertical axis in FIGS. 5 to 8 was a statistical unit (%) in FIGS. 5 and 7, but is represented by a physically meaningful common unit (% / deg) in FIGS. 6 and 8. It will be possible. In addition, in FIGS. 5 and 7, the occupancy rate of each region is added to be 100%, but in FIGS. 6 and 8, the value obtained by definitely integrating the distribution ratio in the entire angle region (range of 0 deg to 90 deg) is 100%. Become. Further, the definite integral value in a specific angle range is the ratio of the surface having the inclination angle in the angle region to the total incident surface, that is, the occupancy rate.

Although details are omitted, when the concave-convex-shaped surface is formed of a transparent material such as the concave-convex layer 13, the distribution rate of the inclination angle θ3 may be calculated as follows. A parallel light beam is incident on the uneven surface, and the luminosity distribution of the obtained transmitted light is measured. Then, the differential equation that is the definition formula of the light intensity distribution and the differential equation that is the definition formula of the inclination angle distribution are solved at the same time. Thereby, the distribution rate of the inclination angle θ3 of the uneven surface may be calculated.

As a result of examining various uneven-shaped surfaces, the inclination angle distribution of the uneven-shaped surface of the uneven sheet 11 used as the base material of the screen 10 is such that the distribution rate at an inclination angle θ3 of 18 deg is 2.0% / deg or more. It was found that it is appropriate that the distribution rate at an angle θ3 of 25 deg is 0.3% / deg or more and the occupancy rate of the inclination angle θ3 of 40 deg or more is 20% or less. Here, the occupancy rate of the inclination angle θ3 of 40 deg or more means a value obtained by integrating the distribution rate in the range of the inclination angle of 40 deg or more. With this configuration, the screen 10 can diffusely reflect the image in the range observed by the person 40, and can suppress the total reflection in the screen 10.

On the other hand, the arithmetic average roughness (Ra) of the concave-convex-shaped surface, the average pitch between a plurality of concave portions and the convex portions formed on the concave-convex-shaped surface, etc. affect the ease of bonding and the definition of the image. do. Further, when a plurality of concave portions or convex portions formed on an uneven surface have a periodic structure, a moire phenomenon may occur due to the relative pitch between the plurality of concave portions or convex portions and the pixels of the image.

As a result of the examination, it was found that it is appropriate that the arithmetic mean roughness of the concave-convex-shaped surface of the concave-convex sheet 11 is 0.5 μm to 2 μm. Further, it was found that the plurality of concave portions and convex portions formed on the uneven surface are randomly arranged, and it is appropriate that the average pitch between the plurality of concave portions and the convex portions is 5 μm to 20 μm. .. Further, it was found that it is appropriate that the uneven layer 13 has a thickness of 5 μm to 20 μm. Further, the thickness of the uneven layer 13 means an average value of the thicknesses of the uneven layer 13. With this configuration, the screen 10 can display a high-definition image and suppress the moire phenomenon.

When the image projected from the projector 30 is incident on the screen 10 as shown by the solid arrow as shown in FIG. 2, it is diffusely reflected by the reflecting layer 14 formed on the uneven surface as shown by the broken line arrow. Then, the person 40 observes a part of the diffusely reflected light as an image. Further, the remaining light of the image projected from the projector 30 that is not reflected and absorbed by the reflection layer 14 passes through the reflection layer 14 and is emitted to the outside of the screen 10 as shown by the arrow of the alternate long and short dash line.

As described above, the brightness of the image displayed by the screen 10 is related to the reflectance of the screen 10, and is particularly proportional to the diffuse reflectance. Therefore, when displaying an image, it is desirable that the diffuse reflectance of the screen 10 is high. However, when the image is not displayed, the higher the diffuse reflectance of the screen 10, the more the ambient light such as the illumination on the person 40 side is diffusely reflected by the screen 10, and the screen 10 looks whitish. Further, the higher the reflectance of the screen 10, the lower the transmittance, so that the background transmitted through the screen 10 becomes dark. Therefore, if the diffuse reflectance of the screen 10 is set too high, the visibility of the background deteriorates.

On the other hand, the background light incident from the window 20 side as shown by the thick arrow is partially diffusely reflected by the reflection layer 14 by the same mechanism as the image projected from the projector 30 (not shown). Then, the remaining light of the background light that is not reflected and absorbed by the reflection layer 14 passes through the reflection layer 14 and reaches the person 40 as shown by the arrow of the alternate long and short dash line.

At this time, the uneven layer 13 and the adhesive layer 15 are both made of a transparent resin material and have a refractive index of about 1.5, which is substantially the same. Therefore, the projected image is transmitted straight ahead without being refracted, and is emitted from the screen 10 at the same angle as the incident light indicated by the solid line arrow as shown by the alternate long and short dash line arrow. In order not to generate even a slight refraction, it is desirable to adjust the refractive index of the transparent material of the concave-convex layer 13 and the refractive index of the transparent material of the adhesive layer 15 so as to be exactly the same. The brightness of the observed background is proportional to the transmittance of the screen 10. Therefore, it is desirable that the screen 10 has a high transmittance from the viewpoint of transmitting the background.

On the screen 10, the remaining light that is not transmitted and reflected is absorbed. Absorption may inevitably occur as a property peculiar to the material, or may be imparted to the material in anticipation of a special effect. Absorption reduces the brightness of both the image and the background. Therefore, the absorption is preferably small so as not to reduce the brightness of the image and background. However, by increasing the absorption, it can be expected to have an effect of suppressing a decrease in contrast due to external light when displaying an image.

As described above, in order for the screen 10 to function as a reflective transparent screen, it is necessary for light to be appropriately distributed for transmission, reflection, and absorption, and the distribution balance differs depending on the intended use scene.

As a result of the examination, it is desirable that the screen 10 has a diffuse reflectance of 5% or more in order to display an image brightly. The screen 10 preferably has a diffuse reflectance of 50% or less and a transmittance of 30% or more in order to enhance the visibility of the background when the image is not displayed. In other words, it is desirable that the screen 10 has a transmittance of 30% or more with respect to visible light and a diffuse reflectance of 5% to 50% with respect to visible light. Absorption is tolerated or positively imparted to the extent that it does not deviate from this condition.

As described above, in the present embodiment, the screen 10 is a screen having reflectivity for diffuse-reflecting the image projected from the projector and transparency for transmitting the background, and is semi-transparent with the uneven sheet 11. A reflective layer 14 and a transparent layer are provided. The concavo-convex sheet 11 is made of a transparent material, and one main surface is a flat surface, and the other main surface is an concavo-convex surface on which a plurality of concave portions and convex portions are formed. The reflective layer 14 is formed on the uneven surface of the concave-convex sheet 11. The transparent layer covers the reflective layer 14. The reflective layer 14 is made of a thin film having a thickness of 2 nm to 1 μm.

As a result, the light incident on the screen 10 from the background side is less likely to be refracted in the screen 10. Therefore, the screen 10 can transmit the background with high sharpness.

Further, the light incident on the screen 10 is diffusely reflected by the semitransparent reflective layer 14 and displayed as an image, so that the light is not diffused more than necessary in the screen 10. Therefore, the screen 10 can display an image with high sharpness.

Further, the reflective layer 14 can transmit and reflect light even if it does not have a remarkable wavelength dependence. Therefore, the screen 10 can transmit a background having a color close to the original color and display an image having a color close to the original color.

Hereinafter, examples will be described.

(Example 1)
A coating liquid in which copolymerized acrylic beads were dispersed in an acrylic UV curable resin ink was applied onto a transparent PET film and cured to form a transparent concavo-convex sheet 11. By adjusting the dispersion concentration of the beads, the viscosity of the UV curable resin ink, and the effect conditions, the concavo-convex sheets 11 of Examples 1 to 3 and Comparative Examples 1 and 2 having different concavo-convex shapes were obtained.

FIG. 9 is a photomicrograph of the uneven surface of Example 2, and FIG. 10 is a diagram showing the distribution ratio of the inclination angles of the uneven surface of Examples 1 to 3 and Comparative Examples 1 and 2. In FIG. 10, the horizontal axis is the inclination angle [deg] and the vertical axis is the distribution rate [% / deg].

The inclination angle distribution in FIG. 10 was calculated from the light intensity distribution obtained by injecting parallel light rays from the uneven surface of the concave-convex sheet 11 and measuring its transmission and scattering characteristics.

In addition, for reference, the inclination angle distribution of the hemisphere is also shown in FIG. In the hemisphere, if the unit of angle is [rad] and the unit of distribution rate is [/ rad], the distribution rate B (θ) with respect to the inclination angle θ is B (θ) = sin (2 ・ θ), and the angle. A peak value of 1.0 is shown at θ = π / 4 (= 45 deg). In this case, in FIG. 10, the peak value = 1.0 × π / 180 × 100 ≈ 1.75 (% / deg) at an angle of 45 deg.

The hemisphere is also described here because the spherical surface is the simplest and most well-known curved surface, and the parallel light flux is almost reflected by the Lumbershan light distribution. Therefore, the reflection light distribution characteristics of the uneven surface can be roughly estimated by comparing and referring to the inclination angle distribution with the inclination angle distribution of the hemisphere.

As shown in FIG. 9, a plurality of concave portions and convex portions formed on the concave-convex-shaped surface of the concave-convex sheet 11 were randomly arranged. Further, the luminous intensity distribution measured by incident parallel light from the uneven surface by the above-mentioned method was a rotation target with respect to the optical axis. From this, it is estimated that the uneven shape is locally asymmetric, but the macro has no in-plane directionality, and the inclination angle distribution in FIG. 10 is calculated on the premise of symmetry, and the inclination angle is in the direction. Regardless, the distribution rate is the same for tilt angles with the same absolute value.

Next, a dielectric multilayer film having a thickness of 0.88 μm was formed on the uneven surface of the concave-convex sheet 11 by a sputtering method to form a semitransparent reflective layer 14.

The dielectric multilayer film is composed of a plurality of niobium pentoxide (n = 2.33), which is a transparent dielectric material having a high refractive index, and silicon dioxide (n = 1.46), which is a transparent dielectric material having a low refractive index. It was formed by laminating layers.

An adhesive layer 15 made of an acrylic adhesive was formed on the surface side of the uneven sheet 11 on which the reflective layer 14 was formed so as to cover the reflective layer 14. As a result, the screen 10 can be adhered to the window made of glass material. As described above, the screen 10 was created.

Table 1 and FIGS. 11 to 11 show the physical characteristics consisting of the surface uneven shape and the optical characteristics, and the performance evaluation by projecting an image with an ultra-short throw projector for the examples and comparative examples configured as described above. It is shown in FIG.

図１１は分光光度計にて透過率、反射率を測定し、視感度で加重平均して実効透過率、実効反射率を算出した結果を、凹凸形状の面の傾斜角の順に並べたグラフである。

FIG. 11 is a graph in which the transmittance and reflectance are measured with a spectrophotometer, and the results of calculating the effective transmittance and the effective reflectance by weight averaging by the luminosity factor are arranged in the order of the inclination angle of the uneven surface. be.

As shown in Table 1 and FIG. 11, Comparative Example 1, Example 1 and Example 2 in which the component ratio of the inclination angle of 40 deg or more is 0.2 or less show almost the same reflectance of about 28%, and 40 deg or more. In Example 3 in which the component ratio of the inclination angle was relatively large (20%), the reflectance was reduced to 24%. Further, in Comparative Example 2 in which the component ratio of the inclination angle of 40 deg or more was 27%, the reflectance was as low as 17%. This is because the light reflected at an inclination angle of 21 deg or more is totally reflected at the air interface of the uneven sheet 11 and cannot be effectively emitted, and it is considered that the light propagates in the surface direction in the sample and becomes an invalid component. ..

Tables 1 and 12 are calculated by taking the ratio of the total light transmittance in which all the transmitted components are supplemented by the integrating sphere and the diffused light transmittance in which only the diffused light is supplemented by providing an opening for allowing the straight ray to escape. It is a haze characteristic.

As shown in FIG. 12, Comparative Examples 1 to 3 in which the component ratio of the tilt angle of 40 deg or more is low shows good transparency with a transmission haze of 2.0% or less, and the component ratio of the tilt angle of 40 deg or more is 27%. Comparative Example 2 had a haze value of more than 10%.

FIG. 13 shows the result of measuring the brightness of light reflected in the normal direction of the screen surface by injecting light from various angles, and standardizing the result by the brightness in the case of perfect diffuse reflection (Lumbershan light distribution with 100% reflectance). It is shown by the converted front gain. In order to show the front gain over a wide range of incident angles in the same graph, the vertical axis is displayed on a logarithmic scale.

As shown in FIG. 13, Comparative Example 1 showed a large gain with respect to an incident angle of 20 deg or less, but showed a low value of 0.11 at an incident angle of 60 deg near the center of the screen in the ultra-short throw projector.

On the other hand, Examples 1 to 3 maintain a relatively high gain in the standard incident angle range of 25 deg to 70 deg in the short focus projector.

Next, an image was projected and evaluated by an ultra-short throw projector equipped with an ultra-short throw lens ET-DLE030 on a Panasonic projector PT-DX100. The incident angle of the projected light was about 60 deg at the center of the screen, about 30 deg at the lower end, and about 70 deg at the upper end. The evaluation results are shown in Table 1.

Comparative Example 1 had transparency comparable to that of a normal window glass, and the image sharpness of the part where the image could be recognized such as the lower end was high, but the brightness decreased sharply as the projection angle became larger. The uniformity of brightness was significantly inferior.

Example 1 had transparency close to that of Comparative Example 1 in terms of background visual recognition, the central portion of the projected image was bright, the uniformity of brightness was at a practical level, and the image display performance was excellent in sharpness.

Example 2 had sufficient transparency for visual recognition of the background, and was excellent in the balance of brightness uniformity, sharpness, etc. of the projected image.

Example 3 was slightly inferior in transparency to Examples 1 and 2, but had sufficient background visibility, and the projected image had high uniformity and brightness over the entire surface.

In Comparative Example 2, the projected image was slightly dark on the entire surface and the sharpness was low, but the uniformity was excellent and the display quality was tentatively shown, but the transparency was low and there was a problem in the background visibility.

In addition, as a result of various studies, the distribution rate is relatively high at each 18 deg, which is the angle at which light with an incident angle of 60 deg is reflected near the front in order to obtain sufficient brightness in the center of the image, and is 2.0% / deg or more. In order to obtain the minimum required viewing angle and brightness at the assumed maximum incident angle of 75 deg, the distribution rate at an inclination angle of 25 deg must be 0.3% / deg or more, and good background visibility is required. In order to obtain the desired transparency, it was found that the occupancy rate of the inclination angle of 40 deg or more is preferably 20% or less.

(Other embodiments)
In the above embodiment, PET is used as the material of the base sheet 12, but the material of the base sheet 12 is not limited to PET. The material of the base sheet 12 may be a transparent resin material, for example, polymethyl methacrylate resin (PMMA), polycarbonate, or the like.

Further, although the concavo-convex layer 13 is formed by applying the acrylic ultraviolet curable resin and the copolymerized acrylic beads, the method for forming the concavo-convex layer 13 is not limited to this. The uneven layer 13 may be formed by using another ultraviolet curable resin or resin beads.

Further, in the above embodiment, the transparent adhesive liquid in which transparent spherical fine particles are dispersed is coated and cured to form the uneven layer 13, but the shape is transferred with a UV curable resin or the like using a mold to form the uneven layer. 13 may be formed.

Further, in the above embodiment, the reflective layer is formed of a dielectric multilayer film, but a metal film such as nickel or aluminum may be laminated by several tens of nm.

Further, in the above embodiment, the transparent layer covering the reflective layer 14 is composed of the adhesive layer 15, but the transparent layer may not be composed of only the adhesive layer 15. The transparent layer may be composed of the adhesive layer 15 and the window 20. That is, a transparent layer covering the reflective layer 14 may be formed by attaching the adhesive layer 15 made of a transparent acrylic adhesive to the window 20 which is a transparent base material made of glass. Further, for example, a transparent resin material such as PMMA or polycarbonate may be used for the window 20, or a thermosetting transparent material may be used for the adhesive layer 15.

Further, depending on the application, the screen 10 may include a transparent layer made of a transparent resin containing no adhesive instead of the adhesive layer 15.

The screen according to the present disclosure transmits a background of a color close to the original color with high sharpness even if a projector having a light source other than the laser light source is used, and displays an image of a color close to the original color with high sharpness. can. Therefore, the present disclosure is useful as a screen or the like having a reflectivity that diffusely reflects an image projected from a projector and a transparency that allows the background to pass through.

10 Screen 11 Concavo-convex sheet 12 Substrate sheet 13 Concavo-convex layer 14 Reflective layer 15 Adhesive layer (transparent layer)
20 windows 30 projectors 40 people

Claims (9)

A screen having the reflectivity of incident an image projected from a projector at an incident angle of 75 deg and diffuse reflection of the image in the normal direction of the surface and the transparency of transmitting the background.
An uneven sheet made of a transparent material, one main surface of which is a flat surface, and the other main surface of which is an uneven surface having a plurality of concave portions and convex portions formed therein.
A semi-transparent reflective layer formed on the concave-convex-shaped surface of the concave-convex sheet, and
A transparent layer covering the reflective layer is provided.
The distribution of the inclination angle formed by the tangent line at the point where the light of the image is reflected on the uneven surface and the main surface of the uneven surface is 2.0% / deg or more when the inclination angle is 18 deg. A screen having a distribution rate of 0.3% / deg or more at an inclination angle of 25 deg. The screen according to claim 1, wherein the reflective layer is made of a metal of nickel, aluminum, silver, or chromium, or an alloy containing any of nickel, aluminum, silver, or chromium as a main component. The screen according to claim 1, wherein the reflective layer is a dielectric multilayer film in which a plurality of transparent dielectric materials having a high refractive index and a transparent dielectric material having a low refractive index are alternately laminated. The surface having an uneven shape has an arithmetic mean roughness of 0.5 μm to 2 μm.
The plurality of concave portions and convex portions are randomly arranged, and the plurality of concave portions and convex portions are randomly arranged.
The screen according to claim 1, wherein the average pitch between the plurality of recesses and the protrusions is 5 μm to 20 μm. The screen according to claim 1, wherein the transmittance with respect to visible light is 30% or more, and the diffuse reflectance with respect to visible light is 5% to 50%. The screen according to claim 1, wherein the transparent layer is an adhesive layer made of an adhesive. The screen according to claim 1, wherein the uneven sheet is composed of a base material sheet and an uneven layer. The screen according to claim 7, wherein the uneven layer has a thickness of 5 μm to 20 μm. An image display including a projector and a screen having a reflectivity of incident an image projected from the projector at an incident angle of 75 deg and diffusely reflecting the image in the normal direction of the surface and a transparency of transmitting the background. It ’s a system,
The projector is a short focus projector that projects the image at an incident angle in the range of 25 deg to 75 deg with respect to the screen.
The screen is
An uneven sheet made of a transparent material, one main surface of which is a flat surface, and the other main surface of which is an uneven surface having a plurality of concave portions and convex portions formed therein.
A semi-transparent reflective layer formed on the concave-convex-shaped surface of the concave-convex sheet, and
It has a transparent layer that covers the reflective layer, and has
The distribution of the inclination angle formed by the tangent line at the point where the light of the image is reflected on the uneven surface and the main surface of the uneven surface is 2.0% / deg or more when the inclination angle is 18 deg. A video display system having a distribution rate of 0.3% / deg or more at an inclination angle of 25 deg.

Images