JPS62145233A - Lens sheet for reflection type screen - Google Patents

Abstract

PURPOSE:To obtain a proper horizontal and vertical spread of reflected light according to the purpose of use by providing plural lenticular lenses vertically on the opposite surface from an incidence surface for projection light and providing beltlike reflecting layers which reflect incident light to convex parts of the lenses. CONSTITUTION:A lens sheet 1 consists of the incidence surface 2 and a lens surface 3 on the opposite side from it. The lens surface 3 is provided plural lenticular lenses 4 successively and beltlike light reflecting layers are provided to convex parts of the lenticular lenses. A back sheet 6 has a base material 7 and a light absorbing layer 8 to absorb light leaking from the lens sheet 1 and also cut off external light incident in the opposite direction from the incidence surface for the projection light, so a reflection type screen is constituted by using it in combination with the lens sheet 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lens sheet suitable for use in a reflective screen on which images are projected and viewed from the viewer's side.

[Conventional technology]

As reflective screens for slides, movies, and video projectors, screens with diffusely reflective surfaces are used, such as flat white plates or slightly uneven substrates covered with aluminum foil, etc. .

Such a conventional reflective screen does not emit light other than projection light.
For example, when exposed to external light such as indoor illumination light, the contrast of the projected light decreases and image quality deteriorates.

In addition, there is no difference in the distribution of reflected light in the vertical and horizontal directions,
Considering the relationship between the general viewing position and the screen, the horizontal spread is insufficient, but the vertical spread is excessive, which poses a problem in terms of effective use of reflected light.

[Problems to be solved by the invention]

In the present invention, the drawbacks in the conventional technology are solved,
Provides a lens sheet for use in manufacturing reflective screens that prevents the contrast of projected light from decreasing due to external light and deterioration of image quality, widens the spread of reflected light in the horizontal direction, and suppresses the spread in the vertical direction. It is intended to.

[Means for solving problems]

The present invention is characterized in that a plurality of lenticular lenses are provided in the vertical direction on the surface opposite to the incident surface of the projection light, and a band-shaped light reflection layer that reflects the incident light is provided on the convex portion of the lenticular lens. The object of the present invention is to provide a lens sheet J for a reflective screen, which is characterized by:

FIG. 1 shows a lens sheet 1 for a reflective screen according to the present invention in its used state, and for the sake of clarity, the lens sheet 1 and the back sheet 6 are drawn separated.

The lens sheet 1 is made up of a surface on which projection light enters, that is, an entrance surface 2, and a lens surface 3, which is the opposite surface.

On the lens surface 3-, a plurality of lenticular lenses 4 are arranged in a line in the vertical direction when viewed from a normal observer's posture, and the convex portion of each lenticular lens has a band-shaped strip in the vertical direction. A light reflective layer is provided.

In Figure 1, 6 is the back sheet, 7 is its base material,
Reference numeral 9 denotes a light absorption layer, which is used in combination with the lens sheet 1 in order to absorb light leaking from the lens sheet 1 and block external light entering from the direction opposite to the incident surface of the projection light. This constitutes a reflective screen.

Lens Sea) 1 is made of a material with high transparency and a high refractive index, and is made of transparent synthetic resin such as acrylic or meccrylic resin such as polymethyl methacrylate, polyvinyl chloride resin, or polycarbonate resin, or glass.

Considering ease of molding, mass production, and light weight, it is best to use transparent synthetic resin.

FIG. 2 is a horizontal cross-sectional view of the device shown in FIG. 1, cut in the horizontal direction.

As the horizontal cross-sectional shape of the lenticular lens 4, parts of various curves, such as a circle, an ellipse, a parabola, a hyperbola, or a part of a sine curve, are used.
By selecting such a horizontal cross-sectional shape and the refractive index of the lens sheet, it is possible to obtain the desired spread of reflected light.

As an example, when making a lens sheet from polymethyl methacrylate with a refractive index of 1.49, a part of an ellipse with a ratio of 0°7 in the major axis (thickness direction of the lens sheet) and 0.5 in the minor axis is horizontally sectioned. When parallel light is incident on a lenticular lens sheet, the horizontal spread angle is ±50@, and if the major axis is 0.8 and the minor axis is 0.5, it is ±40@, and the major axis is 0.5. 9. If the short axis is 0.5, it is ±30".

Here, the angle of spread is the angle measured from the optical axis direction of the lens to the direction of the observation position where the maximum reflection intensity (usually the maximum on the optical axis of the lens) of 172 is ensured.

The light reflecting layer 5 is provided on the convex portion of the lenticular lens 4 and reflects incident light from the incident surface 2 side.

The light rays shown at 9 in Fig. 2 that are incident on the total reflection surface of the lenticular lens are reflected by the lens surface and emitted to the observer side, but the light rays shown at 10 in Fig. 2 are reflected by the total reflection surface of the lenticular lens. Ji! Without f5, light is not reflected by the lens surface and is transmitted through the lens surface. Therefore, the light reflecting layer 5 only needs to be provided in the area where the light rays incident on the lens sheet are not totally reflected by the lens surface, and it is not preferable to provide it in front of the lens surface because it increases the reflectance of external light.

Figure 3 is a diagram for explaining the area of the first half of the incident light, and 11 to 15 are light rays that are incident on the lens sheet and parallel to the optical axis of the lens. With respect to the normal, A1. ~A, has an angle of r. A7
7 - Assuming that the angle of A, j is θ and the refractive index of the lens sheet is n, when nxs in θ>1, total reflection occurs,
When 1Xsinθ≦1, the light ray exits downward in FIG. 3 and is not reflected back to the incident side. n-1
,49, then nX5inθ-1 when θ-42,2@
If the angle θ is smaller than this, the incident light will pass through as it is.The normal line at 14.15 in FIG. 3 shows how it is transmitted because θ is small.

Therefore, it is best to provide the light reflective layer in a smaller angle range with the boundary being θ that satisfies nX5inθ〉1, that is, θ-s+n (1/1.49). In Figure 3, only the right half is shown. However, the same applies to the left half.

Figure 4 explains the absorption and blocking of external light, and like the projection light 16, the lens sheet! A light ray that enters from a direction close to the optical axis direction of the lens enters the lens, repeats reflection, and then is reflected back to the incident side, but a light ray that enters at a considerable angle from the optical axis direction of the lens, such as ray 17, No total reflection occurs, light reflection I! ! Since the light is transmitted through the lens in the area where 5 is not provided, it is not reflected. On the contrary, it is better not to have a light reflecting layer in this part.

As shown in FIG. 4, in an example of using the lens sheet of the present invention, a back sheet is prepared in which a light absorbing layer 8 of black or the like is provided on another base material 7, and the light absorbing layer 8 side is placed on the lens sheet. Since it is touching the lens surface, the transmitted light of 16° is light absorption I? !
The external light 18 is absorbed by the light absorbing layer 8 and is absorbed by the light absorbing layer 8 even if the base material 7 is transparent. ,
It does not affect the observer. For the same purpose, the lens surface,
In particular, it is also good to directly provide a light absorbing layer in a portion where there is no light reflecting layer.

The light reflection N5 provided in the range as described above can be provided, for example, by the thermal transfer method shown in FIGS. 9 to 12.

FIG. 9 illustrates the structure of the transfer film A used in the thermal transfer method, and is peeled off onto the base film 21. An i11 layer 22, a light reflecting layer 23, and a thermal adhesive layer 24 are provided in this order. The base film 21 is preferably a polyethylene terrestrial film having a thickness of 70 to 100 μm.

FIG. 10 is a simplified representation of the thermal transfer method. 1st
0 [iJ] Place the lens sheet 1 with the lens side facing up and attach the transfer film tightly. From above, 70~
When pressure is applied with a rubber roll heated to 100° C., pressure is applied only to the convex portion of the lens, and the light reflecting layer 5 is transferred only to that portion.

As shown in FIG. 11, the width of the light reflective layer 5 transferred to the lens sheet 1 depends on the area over which the pressure from the rubber roll is transmitted, so by changing the hardness and pressure of the rubber, a certain degree of freedom can be achieved. As shown in FIG. 12, the light reflecting layer 5 having the required width can be provided on the lens sheet 1 by any of the above methods that allow the lens sheet to have the following properties.

Next, the spread of reflected light in the vertical direction of the lens sheet will be explained.

What is the spread of reflected light in the horizontal direction? jfAs you can understand, it should be fairly wide if you assume that several people will be watching side by side, but the vertical spread is better if the viewer is standing, sitting, or lying on the floor. It is sufficient to cover the range of 1/2 of the maximum intensity of the reflected light, and normally, when viewing from a seated position, it is sufficient to secure 1/2 of the maximum intensity of the reflected light within the range of ±5'' to ±10@.

The spread of the reflected light in the vertical direction can be achieved by making the incident surface of the lens sheet surface a diffusing surface. Problem 5 Figure 1 is part 1.
This lens sheet l is an example of lens surface 3.
is made of the same lenticular lens as the one in Figure 1, but the entrance surface on the opposite side is a finely uneven surface. FIG. 6 shows another example, in which the plane of incidence is horizontally divided by 1t (t
This is a solid lenticular lens 20.

In the case of the lens sheet shown in FIG. 5, the entrance surface can be formed with predetermined irregularities by embossing, sandblasting, applying matte paint, pasting a light diffusing sheet, etc. during or after manufacturing the lens sheet. This method not only controls the spread of light in the vertical direction, but also prevents incident light from being reflected as it is and appearing to shine partially.

In the case of FIG. 5, both incident light and reflected light are transmitted through the diffusing surface. Therefore, as shown in FIGS. 7 and 8, a large diffusion effect can be obtained even with a weak diffusion surface. FIG. 7 shows the state of diffusion in the horizontal direction, and FIG. 8 shows the state of diffusion in the vertical direction.

The lens sheet shown in FIG. 6 can be made by molding a predetermined shape on the front and back surfaces when making the lens sheet. 6th
In the case shown in FIG. 5, only the horizontal expansion can be made relatively large compared to the case shown in FIG. Furthermore, it is relatively easy to determine the spreading characteristics as desired. If a lenticular lens is simply provided, the incident light is likely to be reflected as it is on the incident surface, resulting in parts that appear to be distorted, so it is preferable that the surface of the lenticular lens on the incident surface be a diffusion surface that has a weak diffusion effect.

[Action/effect of the invention]

In the present invention, the spread of reflected light in the horizontal direction is controlled by a plurality of vertically arranged lenticular lenses and a light reflective layer on the convex portion of the lens, so that the spread of reflected light is controlled based on the optical characteristics of the lens. It is determined.

Furthermore, since external light from the viewer side is transmitted through the portion where the light reflective layer is not provided, reflection of external light can be suppressed.

Furthermore, the spread of the reflected light in the vertical direction can be controlled by designing the diffusing surface of the incident surface separately from the spread in the horizontal direction, and the spread can be reduced by 1 m, thereby improving the utilization rate of the reflected light.

Therefore, if the lens sheet for a reflective screen of the present invention is applicable to a reflective screen, there will be no problem in observing the projected image even in a bright room during the day or under illumination, and it can be adjusted in the appropriate horizontal direction and direction depending on the application. It is possible to obtain the spread of reflected light in the vertical direction.

[Brief explanation of drawings]

FIG. 1 is a perspective and perspective view of an example of the use of the lens sheet of the present invention, and FIG. 2 is a cross-sectional view showing a usage state of the lens sheet of the present invention.
3, 4, 1, 7, and 8 are diagrams for explaining the situation after the incident light enters. 9 to 12 are diagrams showing a method of providing a light reflecting layer.

Claims (6)

[Claims] (1) A plurality of lenticular lenses are provided in the vertical direction on the surface opposite to the incident surface of the projection light, and a band-shaped light reflection layer that reflects the incident light is provided on the convex portion of the lenticular lens. A lens sheet for reflective screens characterized by: (2) A light-reflecting layer is provided in the area where the angle between the ray of light incident in the direction perpendicular to the screen and the normal line when it hits the lenticular lens surface is less than sin^-^1 (1/n). Claim 1 characterized in that
Lens sheet for reflective screens as described in Section 1. (3) A lens sheet for a reflective screen according to claim 1 or 2, wherein the incident surface is a diffusing surface. (4) The lens sheet for a reflective screen according to claim 3, wherein the entrance surface is a finely uneven surface. (5) A lens sheet for a reflective screen, characterized in that the incident surface is composed of a plurality of lenticular lenses provided in the horizontal direction. (6) Claim 3, characterized in that a light diffusing sheet is bonded to the incident surface to form a diffusing surface.
Lens sheet for reflective screens as described in Section 1.