JP2004062099A - Visibility improving sheet, display using the same and a transmission type projection screen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image with high visibility for numerous observers, because it improves the narrowness of the angle of visual field which was a problem with conventional visibility improvement sheet, by providing a layer having a function of diffusing light as a second layer at the observer's side of a conventional type visibility improvement sheet having the function of absorbing the outside light and prevent the contrast from lowering or the like, when the outside light reaches the display. <P>SOLUTION: A light diffusion layer 31 is provided at the observer's side of a first layer (a layer including a light absorbing layer) 2 as a second layer. The light diffusion layer 31 of this second layer consists of a base material, having almost the same refractive index with the first layer 2 ( for example the refractive index difference between the first layer and the second layer is smaller than 0.1), and fine particles, whose refractive index is different from this base material (made of glass beads or resin beads, and the difference of the refractive index with the base material is preferably smaller than 0.2, or more preferably smaller than 0.05), that is a dispersing agent. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is installed on the front side of the viewing side of the display, the performance of the display, in particular, a reduction in contrast when the display is exposed to external light, a glare, a function to prevent a reduction in performance due to reflection of an image, The present invention relates to a visibility improving sheet having a function of appropriately diffusing effective light of a display to widen a viewing angle, a display using the sheet, and a display member (transmission projection screen) using the sheet.
[0002]
[Prior art]
FIG. 12 shows an example of a conventional visibility improving sheet 41. In this figure, reference numeral 3 denotes a display such as a liquid crystal, a PDP, an organic EL, a CRT, and a rear projection. When these displays are used under strong external light conditions, such as outdoors, there is a problem in that external light is reflected by the displays, lowering the contrast of images and impairing visibility. In order to solve this problem, a method is well known in which a light absorbing layer is formed on a part of a transparent sheet, and the light absorbing layer is attached to the front surface on the viewing side of the display. This light-absorbing layer is provided substantially in the thickness direction of the sheet, and the other portion is a light-transmitting portion. The layer has a function of absorbing external light obliquely hitting the display and preventing a decrease in contrast (hereinafter, referred to as a first layer). ) Is called a louver. In FIG. 12, reference numeral 2 denotes a first layer, and the first layer 2 is bonded to the surface of the display 3 with the adhesive layer 4. In the first layer 2, some of the external light 6 is refracted on the surface of the first layer 2 and enters the light absorbing layer 22, where it is absorbed. By this effect, the amount of external light 6 reflected by the display 3 is reduced, so that a decrease in contrast due to external light is improved.
[0003]
However, since a part of the image light 5 emitted from the display 3 is also absorbed, the brightness is reduced. In addition, light having an angle larger than a certain angle out of the emitted image light is absorbed by the light absorbing layer 22, causing a problem that the viewing angle of the display 3 is narrowed. Here, this angle will be described. As shown in FIG. 12A, light is emitted from the central portion of the light transmitting portion of the first layer (the same as the central portion of the light absorbing layer 22 formed continuously at a certain pitch with the adjacent light absorbing layer). When the light of the image light 5 of the display 3 is examined, light in the range of -α1 to + α1 passes through the light transmitting portion 21 in the first layer and is emitted assuming that the direction perpendicular to the display is 0 °. Light traveling in other directions is absorbed by the first light absorbing layer 22. Here, α1 is the width L of the light transmitting portion of the first layer (the width of the light absorbing layer of the first layer is narrow and almost the same as the pitch of the light absorbing layer) and the thickness D of the light transmitting portion (see FIG. 12). In the example, the adhesive layer is thin and is substantially equal to the distance from the observation side surface to the display surface), and α1 = tan ^-1 (L / 2D). The image light 5 from the display traveling in the direction of the angle range from -α1 to + α1 is refracted and emitted at the surface of the first layer. Here, if the refractive index of the light transmitting portion 21 of the first layer 2 is n, the light entering the surface of the first layer at an angle of α1 is β1 = sin ^-1 Light is emitted in the direction of (n × sin (α1)). Therefore, the light emitted from the central portion of the light transmitting portion 21 of the first layer spreads in the angle range from -β1 to + β1.
[0004]
When the position where light is emitted from the display 3 has a different relative positional relationship in the width direction with respect to the light absorbing layer 22 of the first layer, the angle range of light that can be emitted from the first layer 2 is also different. As shown in FIG. 12B, when the display light 5 is emitted from the vicinity of the light absorbing layer 22, that is, from the end in the width direction of the light transmitting part 21, the light in the range of 0 ° to α2 is emitted. Becomes effective light, and light at other angles becomes lossy light. Where α2 is
α2 = tan ^-1 (L / D)
Is represented by
As can be seen from this equation, when L / D is not large, 2 × α1 ≒ α2. Therefore, the angle range of the effective light is 2 × α1 in FIG. 12A and α2 in FIG. 12B, and the angle range is substantially equal. Here, if the refractive index of the light transmitting portion 21 of the first layer 2 is n, the light entering the surface at an angle of α2 is 2β = sin ^-1 Light is emitted in the direction of (n × sin (α2)). Therefore, the light emitted from the end of the light transmitting portion spreads from 0 ° to + β2. It can be seen that the effective light from the display from the center of the light transmitting portion 21 to the end has an angular width of about 2 × α1. Therefore, when the image light from the display emits light at an angle larger than this angle, a loss light occurs, and a bright image cannot be delivered to an observer.
In addition, there is also a case where light is emitted from the opposite end in the width direction of the light transmitting portion 21 in the above description of FIG. 12B, and in this case, the sign of the above description is reversed, and from -α2. The light in the range of 0 ° becomes effective light, and spreads in the angle range from -β2 to 0 °. Therefore, the light output range from the light output surface of the first layer 2 is an angle range from -β2 to + β2.
[0005]
When the refractive index n of the light transmitting portion 21 of the first layer 2 is determined, the viewing range is determined by the angles α1 and α2. That is, α1 is determined by the width L of the light transmitting portion 21 and its thickness D. When this ratio (D / L) is large (that is, when the depth D becomes deeper than the opening dimension L), the degree of absorption of external light increases and the contrast improves, but the values of α1 and α2 also decrease. The viewing angle becomes narrow. As described above, the contrast and the viewing angle have an opposite relationship, and it is necessary to set an appropriate value in consideration of practicality. Usually, D / L is set to about 1 to 4. For example, if D / L = 2, α1 = 14.0 °, α2 = 26.6 °, and if n = 1.6, β1 = 22.8 ° and β2 = 45.7 °. Become. Here, the light output in the vicinity of β2 is an angle at which the light of the display emits light from the end of the light transmitting portion, and becomes very dark. It is considered that the effective viewing angle is about halfway between β1 and β2, and the effective viewing angle in this case is about ± 34 °. As described above, when the first layer having the light absorption layer formed by the conventional method is used, the viewing angle becomes narrow.
[0006]
[Problems to be solved by the invention]
As described above, in the conventional visibility improving sheet having the function of preventing the contrast of the display from lowering due to the external light, a part of the image light from the display is absorbed by the light absorbing layer 22 in the first layer and the loss is lost. Thus, there is a problem that the brightness of the display is reduced and the viewing angle is narrowed.
[0007]
[Means to solve the problem]
According to a first aspect of the present invention, there is provided a visibility improving sheet for enhancing the visibility of a display, wherein the visibility improving sheet has two or more layers in a thickness direction from a display surface to an observation side, It comprises a first layer comprising a light transmitting portion including a light absorbing layer formed in the direction and transmitting light from the display, and at least one other layer. A second layer having a function of diffusing light from the first layer to the observation side is formed. The viewing angle limited by the layer including the light absorbing layer of the first layer is added to the viewing side of this layer by adding a second layer having a function of diffusing light, and the effect of the second layer is used to display. The viewing angle (diffusion angle) as a whole was widened.
[0008]
A second invention is the above visibility improving sheet, wherein the second layer having a function of diffusing light utilizes refraction at two interfaces having different refractive indexes. By utilizing the light diffusion effect of refraction at the interface having a different refractive index for the light diffusion layer, the entire surface of the display (that is, the observation side surface of the visibility improving sheet) can be made flat, If the surface has a lenticular shape or the like, it can be prevented from being damaged, and additional processing using a flat surface can be performed.
[0009]
A third aspect of the present invention is the above-mentioned visibility improving sheet, wherein a minute uneven layer which diffuses light is provided as a third layer on the outermost surface on the observation side of the sheet. The reflection can be prevented by the minute uneven layer.
[0010]
The fourth invention is characterized in that a low-reflection layer or a non-reflection layer which lowers the reflectance is additionally formed as a third layer on the outermost surface on the observation side of the visibility improving sheet.
[0011]
The fifth invention is characterized in that the visibility improving sheet is attached to the observation side surface of the transmission type projection screen as shown in FIG.
[0012]
The sixth invention is characterized in that the visibility improving sheet 1 is provided on the display unit observation side of the display 3 as shown in FIG.
[0013]
According to a seventh aspect of the present invention, a half-value angle expressing a viewing range of light emitted from the display, which is incident on the light transmitting portion of the first layer provided on the display portion observation side of the display, is equal to the light of the first layer. It is characterized by being smaller than the maximum angle α2 at which light can be emitted from the light transmitting portion without being absorbed by the absorbing layer. Assuming that the width of the light transmitting portion in the first layer is L and the height (thickness) of the light transmitting portion in the first layer is D, α2 is
α2 = tan ^-1 (L / D).
The diffusion angle (viewing angle) of the display alone is narrowed, so that the display image light is absorbed by the light absorbing layer, the utilization rate (transmission rate) of the display image light is increased, and a bright image is displayed. Is provided to the observer.
[0014]
Here, the half-value angle, which is one of the scales representing the viewing angle (diffusion range) of the image light of the display, measures the light emission (observation) angle dependence of the brightness of the display expressed by luminance or the like, This is a light emission angle at which a half (half value) of the maximum brightness value is obtained. In many displays, the brightness at the front (0 °) is usually the best, and gradually becomes darker as the light output angle increases, resulting in an upwardly convex curve. FIGS. 11A and 11B are examples of light emission angle distribution curves of brightness. In this example, the brightness distribution is different in the horizontal direction (81 and 83) and in the vertical direction (82 and 84), so two curves are represented in one drawing.
[0015]
An eighth invention is the display described above, wherein a transmission type projection screen is used as a display unit of the display.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows one example of the configuration of the visibility improving sheet of the present invention. In this example, a light diffusion layer 31 is provided as a second layer on the observation side of the first layer (layer including a light absorption layer) 2. The light diffusion layer 31 of the second layer includes a base material having substantially the same refractive index as the first layer 2 (for example, a difference in refractive index between the first layer and the second layer is within 0.1), Fine particles having a refractive index different from that of the base material (made of glass beads or resin beads and having a difference in refractive index from the base material preferably within 0.2, more preferably within 0.05), Consists of a diffusing agent. Here, the first layer 2 has the same structure as the louver (D / L = 2) of the above-mentioned prior art example. Therefore, the viewing angle of the first layer alone is effectively about ± 34 °. Here, the thickness and the refractive index of the base material of the second layer, the concentration and the refractive index of the diffusing agent are adjusted, and the light diffusion layer 31 having a light diffusion characteristic close to a Gaussian distribution such that the half value angle is ± 20 °. Is added to the observation side as a second layer, the effective viewing angle can be increased to about ± 55 °. As described above, when the visibility improving sheet having the configuration of the present invention is used, the viewing angle can be greatly increased.
[0017]
The second layer formed on the surface of the first layer 2 may be a lenticular lens layer 32 having a plurality of minute lens shapes as shown in FIG. 2, instead of a layer containing a diffusing agent. This eliminates back scattering of the light from the display due to the diffusing agent, increases the transmittance of the light diffusion layer as the second layer, and improves the light efficiency. Further, reflection of external light generated in the layer 31 containing the light diffusing agent can be eliminated to further enhance the contrast, which is preferable.
[0018]
A further preferred configuration of the present invention is an aspect of the seventh invention. The diffusion of light emitted from the display is not isotropic ± 180 °, but is narrowed to a certain angle range so as to reduce the proportion of light from the display absorbed by the light absorbing layer. For example, as described in the example of FIG. 12 (D / L = 2), as described above, light traveling in a direction other than -14.0 ° to + 14.0 ° is absorbed by the light absorbing layer 22. Occurs, and all light outside the angle range of −26.6 ° to + 26.6 ° is absorbed by the light absorbing layer 22. Therefore, when the range in which the light emitted from the display spreads closer to −26.6 ° to + 26.6 °, the light utilization rate increases accordingly. If the highest priority is given to the light use efficiency, it is desirable that the light use efficiency be within the angle range of -14 ° to + 14 °.
[0019]
On the other hand, if the diffusion range of the light from the display is narrowed in this way, the viewing angle is also narrowed accordingly, so that it is necessary to diffuse the light further on the observation side of the first layer. Therefore, one of the preferable configuration examples of the present invention is to narrow the angle range of the light emitted from the display to reduce the rate of light absorption in the first layer, and to reduce the light absorption in a wider range on the surface of the first layer. Is to diffuse. Specifically, when the image light from the display is diffused light having a half-value angle of ± 14 ° with respect to the visibility improving sheet under the optical conditions (D / L = 2) in FIG. 1, the louver has a refractive index of 1. 6, the light output range from the first layer is about ± 20 °. When a light diffusion layer having a half-value angle of about ± 20 ° or a layer having a lenticular lens shape is provided as a second layer on the observation side of the first layer, the effective viewing angle can be made ± 40 °. , Can provide the image of the display to many observers.
[0020]
Limiting the diffusion range of the image light of the display to a certain angle range is easy in a rear projection display in which the design of the diffusion angle of light is performed by a transmission projection screen. The design of the diffusion angle in the vertical direction of the transmission type projection screen is easy by adjusting the amount of the diffusing agent in the light diffusion sheet constituting the transmission type projection screen, and the diffusion angle in the horizontal direction of the transmission type projection screen is It can be adjusted by changing the design of the lenticular lens for horizontal diffusion in the light diffusion sheet constituting the transmission type projection screen. Therefore, for example, if the diffusion angle in the vertical direction of the transmission type projection screen is made to be a Gaussian distribution in which the vertical half value angle is about 5 ° by adjusting the content of the diffusing agent, the above half value angle is about ± 20 °. The vertical diffusion angle can be effectively set to about ± 25 ° by combining with the visibility improving sheet having the light diffusion layer.
[0021]
Another preferred configuration example of the present invention is as follows. As shown in FIG. 3, the structure of the first layer 2 is the same as that in FIG. 12, and light incident on the observation side surface of the first layer 2 travels in two directions symmetrically with respect to a direction perpendicular to the display. A mirror-symmetrical mountain-shaped prism lens-shaped layer 33 is formed. Since the image light emitted from the display already has a diffusivity in a certain angle range, the image light emitted from the display is distributed in two or more directions in order to increase the viewing angle on the observation side of the first layer 2. The viewing angle can also be widened by providing a layer having different thicknesses.
[0022]
Still another preferred configuration example of the present invention is an embodiment of the second invention as shown in FIG. Also in this configuration example, the structure of the first layer 2 is the same as that shown in FIG. Then, a lenticular lens layer 32 is formed in a manner similar to that shown in FIG. However, in this embodiment, a layer 34 of a material having a lower refractive index than the layer forming the lenticular lens is formed on the observation side of the lenticular lens layer 32. In this way, light can be diffused at the interface between the lenticular lens layer 32 and the layer 34 of the low refractive index material, and since the outermost surface on the observation side is flat, the surface has irregularities such as a lenticular lens. The resulting scratches are less likely to occur, and it is also possible to easily add additional functions such as antistatic by coating.
[0023]
Consider a refractive index of the lenticular lens layer 32 and a layer 34 of a material having a lower refractive index than the refractive index of the layer forming the lenticular lens formed thereon. The larger the difference in refractive index between the two, the larger the diffusion effect due to refraction is desirable. However, considering a practical material, the material of the lenticular lens layer 32 is a polycarbonate resin having a refractive index of about 1.5 to 1.6. Or a polystyrene resin, an acrylic resin, an epoxy resin, or the like, and as the material of the low refractive index layer 34, a fluororesin having a refractive index of about 1.3 to 1.4 is selected. Is realistically about 0.2 to 0.3.
[0024]
The present invention can be modified in various ways other than those described above. Even if the lenticular lens layer 36 is not formed on the surface of the first layer 2 as shown in FIG. There is no problem even if it is far away. With this configuration, the first layer 2, the lenticular lens layer 36, and the layers thereunder can be separately manufactured and bonded to each other, and mass productivity can be improved. Further, as shown in FIG. 6, a transparent layer 35 may be provided between the first layer 2 including the light absorbing layer and the display 3. Further, as shown at 23 in FIG. 7, the light absorbing layer may have a wedge-like (trapezoidal) shape instead of a narrow rectangular shape in which the cross-sectional shape looks linear.
[0025]
As shown in FIG. 8, a first layer 2 is formed on an optically transparent base material 39, and a second layer having a light diffusion function is formed on the observation side thereof. The pressure-sensitive adhesive layer 4 may be formed on the opposite side. In FIG. 8, the first layer 2 has a light absorbing layer having a wedge-shaped cross section as shown in FIG. 7, and a second layer formed by laminating a chevron prism lens 33 and a low refractive index layer 34. Was. With such a configuration, the light transmission portion 21, the light absorption layer 23, the chevron prism lens 33, and the low refractive index layer 34 in the first layer are sequentially formed by coating or the like using the base material 39 as a base base material. This is preferable because productivity can be increased. In addition, the second layer may be a lenticular lens layer, a combination of this layer and a low refractive index layer, or a diffusion material layer.
[0026]
Further, the cross-sectional shape of the light absorbing layer is not limited to the above-described shape (rectangle or wedge (trapezoid)). In consideration of the direction in which the assumed external light is directed to the display and the direction of the observer of the display, the light absorbing layer has the following characteristics: (a) horizontal when the entire visibility improving sheet is viewed from the observation side as shown in FIG. Direction, (b) a vertical direction, or (c) a lattice shape, or (d) a transmissive part 20 for transmitting light from a display is cylindrical and the other part is a light absorbing layer. It may be. The surface of the visibility improving sheet of the present invention can be deformed to give various performances. That is, a non-reflective layer or a low-reflective layer is formed by multi-layer coating a material having a refractive index lower than that of the material on the outermost surface of the visibility improving sheet of the present invention with a thickness of about の of the wavelength of visible light rays. It may be formed. Further, as in the aspect of the third invention, a functional layer according to the application, such as matting of the surface for preventing reflection, a hard coat for preventing scratching, or an antistatic for preventing adhesion of dust, etc. Can be added.
[0027]
Furthermore, although the description has been given of the case where the light absorbing layer of the first layer in the visibility improving sheet is provided perpendicular to the display surface, the use environment of the display (the direction in which external light hits the display, the main When the direction (position, etc.) of the observer is clear, the light absorbing layer is made to have a certain inclination from the vertical direction of the display according to the conditions to improve the external light absorptivity and balance the viewing angle. Can take.
[0028]
FIGS. 10A and 10B show a case where the large display device 3 is located above the observer 7 using the display, and the external light (assuming sunlight) 6 comes further from above. It is. In this case, since the external light 6 is only from above, the first light absorbing layer 22 may be provided in a direction extending in the horizontal direction as shown in FIG. Further, the light absorbing layer 22 in the first layer in the visibility improving sheet improves the absorption of the external light 6 and advantageously diffuses the light to the observer 7 as shown in FIG. In addition, it is formed not vertically but slightly downward from the display surface.
[0029]
Embodiment 1
Preparation of the visibility improving sheet having the configuration of FIG.
Width of light transmitting portion of first layer: L = 0.5 mm
Thickness of first layer: D = 1 mm
Refractive index of light transmitting portion of first layer: 1.59
Thickness (width) of light absorbing layer of first layer: 0.02 mm
Arrangement of light absorption layer of first layer: type shown in FIG. 9 (a)
Light diffusion layer on the surface which is the second layer: 0.1 mm thick, half angle of diffusion layer ± 20 °
Adhesive layer thickness: 0.03mm
[0030]
[Method of Manufacturing Example 1]
The polycarbonate resin is extruded into a sheet in the form of two layers, one for the light transmitting portion of the first layer and one for the light absorbing layer, and the sheets are laminated at a temperature not lower than the thermal softening point, and then heat-sealed. Let it. This was cut to a thickness of 1 mm to produce a first layer 2. A UV-curable acrylate resin (refractive index: 1.58) containing a light diffusing agent was coated on the first layer 2 as a second layer, and then cured by UV irradiation to form a light diffusing layer 31. . Then, the opposite surface was coated with an adhesive for bonding to a display or the like to form an adhesive layer 4. When the visibility improving sheet thus produced was bonded to a liquid crystal display having a size of 10 inches and a horizontal half-value angle of ± 14 ° and evaluated, it was found that the louver without the light diffusion layer 31 as the second layer had the same outer appearance. The decrease in contrast due to light was prevented. The horizontal viewing angle was greatly expanded to ± 40 °.
[0031]
Embodiment 2
Preparation of the visibility improving sheet having the configuration of FIG.
Width of light transmitting portion of first layer: L = 0.5 mm
Thickness of first layer: D = 1 mm
Refractive index of light transmitting portion of first layer: 1.59
Thickness (width) of light absorbing layer of first layer: 0.02 mm
Arrangement of Light Absorbing Layer of First Layer: Type of FIG. 9B
Lenticular lens (pitch 0.062 mm, radius of curvature of lens 0.038 mm, half value angle of diffusion at this time is about ± 20 °)
Adhesive layer thickness: 0.03mm
[0032]
[Production method of Example 2]
A first layer 2 was prepared in the same manner as in Example 1, and was press-formed using a reverse mold of the lenticular lens to form a lenticular lens 32 on one surface. Then, an adhesive was coated on the opposite surface to form an adhesive layer 4. When the thus-prepared visibility-improving sheet was attached to a liquid crystal display having a size of 15 inches and a horizontal half-value angle of ± 14 ° and evaluated, it was possible to prevent a decrease in contrast due to external light as in the case of a louver without a lenticular lens. Was. The horizontal viewing angle was greatly expanded to ± 40 °.
[0033]
Embodiment 3
Production of visibility improving sheet having the configuration of FIG.
Width of light transmitting portion of first layer: L = 0.5 mm
Thickness of first layer: D = 1 mm
Refractive index of light transmitting portion of first layer: 1.59
Thickness (width) of light absorbing layer of first layer: 0.02 mm
Arrangement of light absorption layer of first layer: type shown in FIG. 9 (a)
The surface is a lenticular lens (pitch: 0.065 mm, lens shape is part of an ellipse having a horizontal diameter of 0.06 mm and a vertical diameter of 0.04 mm), and a low refractive index layer (refractive index 1.3, thickness) 0.1 mm). At this time, the half value angle of diffusion of the surface by the lenticular lens was about ± 15 °.
Adhesive layer thickness: 0.03mm
[0034]
[Method of Manufacturing Example 3]
A first layer 2 was prepared in the same manner as in Example 1, and was press-formed using a reverse mold of the lenticular lens to form a lenticular lens 32 on one surface. A fluororesin (refractive index: 1.3, thickness: 0.1 mm) was coated as a low refractive index layer on the lenticular lens. Then, an adhesive was coated on the opposite surface to form an adhesive layer 4. The lenticular lens surface of the visibility improving sheet was attached to the observation side of the transmissive projection screen having a half value angle at the horizontal direction of ± 40 ° and a half value angle at the vertical direction of ± 5 °. This visibility improving sheet + transmission type projection screen was evaluated using a liquid crystal projector as a light source. A display having a high contrast and a viewing angle of ± 20 ° in the vertical direction without reflection was obtained even in a bright environment exposed to external light.
[0035]
Embodiment 4
Preparation of the visibility improving sheet having the configuration of FIG.
Width of light transmitting portion of first layer: L = 0.12 mm
Thickness of first layer: D = 0.2 mm
Refractive index of light transmitting portion of first layer: 1.55
Thickness (width) of the first layer light absorbing layer: increasing from 5 μm on the display side to 20 μm on the observation side
Arrangement of light absorption layer of first layer: type shown in FIG. 9 (a)
Base material: PET (20 μm thickness)
A mountain-shaped prism lens on the observation side: pitch 0.02 mm
[0036]
[Fabrication method of Embodiment 4]
A transmitting portion of the first layer is formed on a base material 39 (PET, 20 μm thick) by a UV curing method using an inverse of a trapezoidal shape of the transmitting portion (where the UV resin is cured with urethane acrylate). Refractive index 1.55). Next, in order to form a light absorbing layer of the first layer, a two-component curable black ink is embedded in a groove by a wiping method and cured. A prism lens having a 0.02 mm pitch angle-shaped prism 33 was formed thereon by a UV curing method using an inverted shape of the angle-shaped prism lens (here, the refractive index of the UV resin after curing with urethane acrylate was 1.55). Further, a low refractive index layer 34 was formed thereon by coating a fluororesin having a refractive index of 1.3. Thus, the vertically incident light advances obliquely by 10 °. As shown in FIG. 13, the visibility improving sheet 1 is placed on the surface of a transmission projection screen 51 having a horizontal half-value angle of ± 30 ° and a vertical half-value angle of ± 10 ° (the luminance distribution in FIG. When the display was viewed from above, the light-absorbing layer of the first layer and the chevron-shaped prism lens were stuck together with an adhesive so that they were aligned in the horizontal direction as shown in FIG. 9A. As shown in FIG. 14, when the transmission type projection screen is set on the display unit and projected by a liquid crystal projector, the vertical direction half-value angle ± 20 ° (the luminance distribution of FIG. 11B (however, FIG. In the comparison of the above, the vertical axis is relative luminance (brightness), and the display does not consider the absolute value of the luminance.)), And a high-contrast image was obtained even in a bright environment under sunlight. .
[0037]
【The invention's effect】
According to the first invention, when external light is present on the display, a second layer is formed on the observation side of a conventional visibility improving sheet having a function of absorbing external light and preventing a decrease in contrast. By providing a layer having a function of diffusing light, the narrowing of the viewing angle, which has been a problem in the conventional visibility improving sheet, can be improved. Can be provided.
In the second invention, the light diffusion layer, which is the second layer, is made of a material having a different refractive index, and produces a light diffusion effect at an interface generated there. Since light is diffused by the refraction at the interface, the light utilization efficiency is higher than that of the diffusion layer using a diffusing agent, and the surface can be hardly damaged. Further, by utilizing this outermost surface, it is possible to easily add the additional functions of the third invention and the fourth invention. Therefore, a higher performance visibility improving sheet can be provided.
According to a third aspect of the present invention, a fine uneven layer is provided on the observation side surface of the visibility improving sheet to further increase the degree of diffusion, reduce reflection of the surface, and improve the performance of the visibility improving sheet.
The fourth invention is to provide a low-reflection layer or a non-reflection layer on the observation side surface of the visibility improving sheet to further improve the performance of the visibility improving sheet.
A fifth aspect of the present invention is to provide a transmission type projection screen having good performance in which the visibility improving sheet is bonded to a transmission type projection screen to prevent a reduction in visibility due to external light.
A sixth invention is to provide a display with high visibility by mounting the high-performance visibility improving sheet on the viewing side of the display.
According to a seventh aspect of the present invention, there is provided a sheet for improving visibility in which a light emission angle of image light from a display is narrowed so that a loss of image light from the display in a first layer of the visibility improving sheet falls within a small range. This is to provide a brighter image to an observer by reducing light loss.
The eighth invention is to provide a transmission type projection system as a display having good performance, and to design a three-element design including a transmission type screen so as to sufficiently exhibit the performance of the projector and the performance of the visibility improving sheet. Then, the visibility-improving sheet is attached to a transmission-type projection screen to provide a transmission-type projection screen with good performance in which visibility is prevented from being reduced due to external light, and a display with high performance that is bright and has a suitable viewing range. Is provided.
[Brief description of the drawings]
FIG. 1 shows an example of a visibility improving sheet of the present invention (a diffusion layer provided on the surface (observation side) as a second layer).
FIG. 2 shows an example of a visibility improving sheet of the present invention (a sheet provided with a lenticular lens layer on the surface (observation side) as a second layer).
FIG. 3 is an example of a visibility improving sheet of the present invention (a sheet having a mountain-shaped prism lens layer on the surface (observation side) as a second layer).
FIG. 4 shows an example of the visibility improving sheet of the present invention (a lenticular lens layer is provided on the surface (observation side) as a second layer, and a low refractive index layer is further provided).
FIG. 5 shows an example of a visibility improving sheet of the present invention (a sheet provided with a lenticular lens layer as a second layer at a position away from the first layer).
FIG. 6 shows an example of the visibility improving sheet of the present invention (the first layer and the display are separated).
FIG. 7 is an example of the visibility improving sheet of the present invention (the first light absorbing layer has a trapezoidal cross section).
FIG. 8 shows an example of the visibility improving sheet of the present invention (the light absorbing layer of the first layer has a trapezoidal cross section, the first layer is separated from the display, and the second layer has a surface (observation side)). With a mountain-shaped prism lens and a low-refractive-index layer)
FIG. 9 is an explanatory diagram (exemplification) of a position of a light absorption layer of a first layer as viewed from an observation side.
FIG. 10 is an explanatory diagram of an example of a visibility improving sheet in which a first light absorbing layer is inclined downward from a vertical surface of a display.
FIG. 11 is an explanatory diagram of a brightness distribution of a display.
FIG. 12 is an explanatory diagram of a visibility improving sheet according to the related art.
FIG. 13 is an explanatory view in which a visibility improving sheet is arranged on the observation side of a transmission screen.
FIG. 14 is an explanatory diagram in which a transmissive screen with a visibility improving sheet is installed on a display unit of a display.
FIG. 15 is an explanatory diagram in which a visibility improving sheet is provided on a display unit of a display.
[Explanation of symbols]
L: width of the light transmitting portion of the first layer
D: Height (thickness) of the light transmitting portion of the first layer
P: Maximum brightness (brightness)
P / 2: half value (half the maximum luminance (brightness))
1 Visibility improving sheet of the present invention
2 First layer (louver)
3 Display
4 Adhesive layer of visibility improving sheet
5 Image light from display
6 outside light
7 Display observer
8 Sun
9 Ground or floor
20, 21 Light transmitting portion in first layer
22, 23, 24 light absorbing layer
31 Light diffuser layer
32, 36 Lenticular lens provided as second layer
33 Angle-shaped prism lens provided as second layer
34 Low refractive index layer
35 Transparent layer
41 Conventional visibility improvement sheet
51 Transmission projection screen
61 Display
62 light source
63 mirror
64 Display section
81, 83 Horizontal luminance distribution curve
82, 84 Vertical luminance distribution curve

Claims (8)

A visibility-enhancing sheet for enhancing the visibility of a display, comprising a light-absorbing layer formed of two or more layers in the thickness direction from the display surface to the observation side, and formed substantially in the thickness direction of the visibility-enhancing sheet. And a first layer comprising a light transmitting portion for transmitting light from the display and a second layer for diffusing light provided on the observation side of the first layer. Sheet. The visibility improving sheet according to claim 1, wherein the second layer for diffusing light utilizes refraction at two interfaces having different refractive indices. The visibility-improving sheet according to claim 1, wherein a fine uneven layer that diffuses light is provided as a third layer on the outermost surface on the observation side of the sheet. The visibility-improving sheet according to claim 1, wherein a low-reflection layer or a non-reflection layer that lowers reflectance is formed as a third layer on the outermost surface on the observation side of the sheet. A transmissive projection screen, wherein the visibility improving sheet according to claim 1 is attached to an observation side surface. A display provided with the visibility improving sheet according to any one of claims 1 to 4 on a display portion observation side of the display. The half-value angle representing the viewing range of the light emitted from the display incident on the light transmitting portion of the first layer provided on the display portion observation side of the display is not absorbed by the light absorbing layer of the first layer. 7. The display according to claim 6, wherein the angle is smaller than a maximum angle α2 at which light can be emitted from the light transmitting portion.
Here, the half-value angle expressing the visual field range of the light emitted from the display and incident on the light transmitting portion is an angle that is half the maximum brightness of the video light emitted from the display.
Α2 is
α2 = tan ⁻¹ (L / D)
Here, L: width of the light transmitting portion in the first layer, D: height in the thickness direction of the light transmitting portion in the first layer. The display according to claim 7, wherein a transmission type projection screen is used as a display unit of the display.

Images