JPH01306822A - Reflection type lenticular screen - Google Patents

Abstract

PURPOSE:To improve the lightness of an image in the central part of a lenticular screen and its right and left ends by arranging a mirror face in contact with the back of a scattering layer placed on the back of a lenticular lens and forming the cross-sectional shape of the back of the mirror face in the shape of an arc with curvature. CONSTITUTION:The mirror face 24 is arranged on the back 12 of the lenticular lens 1 in contact with the back of the extremely thin, scattering layer 3, and the cross-sectional shape of the back 12 of the lenticular lens 1 is formed in the shape of an arc with curvature. Therefore, light transmitting the scattering layer 3 turns into reflected light on the face 24. A scattering intensity distribution 22 is added to a scattering intensity distribution 23 to obtain a composite scattering intensity distribution 25, which substantially increases the quantity of reflected light in the incident direction. As a result, the lightness of an image projected on the lenticular screen can be improved from its central part to both ends.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field to which the invention pertains) The present invention relates to a reflective lenticular screen that projects an image onto a lenticular screen using a projector and views the reflected image stereoscopically.

(Prior Art) One conventional method for displaying three-dimensional images is to project the image onto a lenticular screen and obtain stereoscopic vision from the reflected image.

FIG. 8 shows an external perspective view of a lenticular lens 1 forming a conventional lenticular screen for displaying three-dimensional images.The lens body 2 has a large number of lenses cut in a horizontal plane and each having a semicylindrical cross section. Reference numeral 11 has a semicylindrical shape, and a very thin light diffusion layer 3 is arranged on the back surface 12 of the lens.

A conventional three-dimensional image display method using this lenticular lens is shown in FIG. The figure (A) is a plan view seen from above, and the figure (B) is a side view of (A) seen from the side. This involves arranging two or more projectors 5 that project binocular parallax images onto the observer 4 at the same distance as both eyes, and placing the eyes at the upper or lower position (tilted) of the projectors. This allows for stereoscopic viewing.

This is because when the projection angle θ with respect to the lenticular lens 1 is increased, a phenomenon occurs in which the left and right peripheral parts of the lens become dark. That is, FIG. 10 shows the brightness distribution 7 at the center 6 and the left and right peripheries of the lenticular lens 1, and as shown in the drawing, it can be seen that the brightness at the left and right peripheries is poor and dark compared to the center.

These facts can also be seen from the reflection characteristics (FIG. 11) at each incident angle when the lens surface 11 is irradiated with a light beam from the projector 5. That is, in the vicinity of the lens center 6 in FIG. 10, the light rays strike the lens surface 11 at a right angle or at an angle close to it, so it exhibits reflection characteristics as shown in graph 8 in FIG. The angle of incidence of the light ray hitting the lens surface 11 becomes smaller as it goes to the left and right peripheries.For example, when the angle is 80 degrees to the lens surface, graphs 9 and 70
When it hits in degrees, it will look like graph 10. That is, graph 8
In graphs 9 and 10, the reflected light with the maximum intensity is measured in the same direction as the incident direction, but in graphs 9 and 10, the reflected light with the maximum intensity is dark because the incident direction is different.

The reflected light and transmitted light depending on the angle of incidence on the lens surface described above will be explained in detail. (A) of FIG. 12 shows the state when the reflected light with the maximum intensity shown in graph 8 of FIG. The light beams are separated and reflected on the same line on which the incident light 13 was incident.

On the other hand, (B) in FIG. 12 shows that the incident light 16 incident at a certain angle as shown in the graph 9° and the graph 10 in FIG.
8 and transmitted light 19, and the incident light 16 and reflected light 18 are at the same angle θ1= across a line 20 perpendicular to the back surface 12 of the lens.
At 02, 2 people are reflected. Note that 03 is a critical angle at which total reflection occurs at the reflecting surface 17.

As described above, the direction of the reflected light differs due to the difference in the angle of the light rays incident on the lens surface 11, and as a result, the center of the lens becomes bright and the left and right peripheral parts become dark.

So far, we have talked about the reflection of the person 2 onto the lenticular lens 1, but the diffusion layer 3 acts on this.

FIG. 13(A) shows the case where the diffusion layer 3 has a perfect diffusion surface 3A (this is not expected at present, but is a logical assumption),
The following describes the case of slightly glossy diffused i3B as shown in FIG. 13(B).

In the case of the diffusion layer 3A in FIG. 13(A), even if the incident light 16 at a certain angle hits the diffusion surface 3a, it is scattered evenly in all directions, and the scattering intensity distribution 22 is the same as the observation direction and the diffusion area. If the angle made with modulus 1iI21 is 0, then
-like scattering takes place in proportion to cos e.

On the other hand, the case of FIG. 13 CB) is a diffusion layer that can be realized with current technology, and unlike in FIG. 13A, the scattered intensity distribution 22 is scattered in one direction with the normal line 21 as the boundary as shown.

That is, for the observer, the brightness is lower than in (A). That is, for the observer in the direction of incidence of the light beam, (A
), the brightness is perceived to be lower.

The functions of the conventional lenticular screen described above can be summarized with reference to FIG. That is.

Incident light 1 at a certain angle on the lenticular lens surface 11
6 is a scattering intensity distribution 22 in the reflection direction and a scattering intensity distribution 2 in the transmission direction due to the light diffusion effect of the diffusion layer 3.
However, most of the incident light becomes transmitted light, and the amount of reflected light is small unless the incident light 16 becomes smaller than the critical angle θ3 (FIG. 12) at which total internal reflection occurs.

This is due to changes in the reflection direction that occur because the lens back surface 12 of the lenticular lens 1 is flat, and the scattering characteristics of the diffusion layer 3, and until now it has been impossible to avoid lowering the brightness of the image. .

(Objective of the Invention) The present invention solves the above-mentioned drawbacks of the conventional lenticular lens, eliminates the transmitted light of the lenticular lens and increases the amount of reflected light, and increases the brightness of the image projected on the lenticular screen from the center. The purpose is to improve the sameness even in the left and right peripheral areas.

(Structure of the Invention) (Characteristics of the Invention and Differences from the Prior Art) In order to achieve the above object, the present invention arranges a mirror surface in contact with the back surface of the diffusion layer provided on the back surface of the lenticular lens,
Further, the lenticular lens is characterized in that the cross-sectional shape of the back surface thereof is formed into a flat surface or a circular arc shape having curvature.

In contrast to the prior art, in which the ratio of transmitted light to incident light is high, the present invention is different in that transmitted light is lost and the amount of reflected light in the incident direction is increased.

(Implementation@) FIG. 1 is a cross-sectional view schematically showing a lenticular lens according to an embodiment of the present invention.The back surface 12 of the lenticular lens 1 has a mirror surface in contact with the back surface of a very thin diffusion layer 3. 24 are arranged.

According to this embodiment, the transmitted light passing through the diffusion layer 3 is reflected on the mirror surface 24 (in the drawing, the surface of the diffusion layer 3 is shown for convenience, but in reality, since the diffusion layer is very thin, it is reflected on the mirror surface 24). (equivalent) is the reflected light.

The scattered intensity distribution 22 is added with the scattered intensity distribution 23 due to the transmitted light (FIG. 14), and a synthesized scattered intensity distribution 25 is obtained, which significantly increases the amount of reflected light in the incident direction.

The reflection characteristics in this case are shown in FIG. 2, with graph 26 showing this embodiment and graph 27 showing the conventional example. The reflection characteristics were measured when the incident light 16 was incident on the lens surface 11 at an angle of 80 degrees. As is clear from this reflection characteristic, it can be seen that the amount of reflection increases not only in the incident direction but also overall compared to the conventional example.

FIG. 3 shows a sectional view of a lenticular lens showing another embodiment of the present invention, and the lenticular lens 1 shown in FIG.
It is formed by the shape of the back surface 12 of the lens. That is, as shown in FIG. 4, the cross-sectional shape of the back surface 12 of the lenticular lens is a part of the circumference (arc) defined by the center point 28 of the lens surface 11 and the radius 29 (also the focal length 30). is formed.

Because of this shape, the light rays that enter the lens (incident light 16) always strike the back surface 12 of the lens, which is the reflective surface, at right angles, and the reflected light 18 is directed in the direction of incidence (on the same axis).

FIG. 3 shows a sectional view of the lenticular lens 1 shown in FIG. 4, where the pitch 31 on the front surface 11 of the lens and the pitch 32 on the back surface 12 of the lens are the same and have a corresponding positional relationship. Then, the diffusion layer 31 and the mirror surface 24 are placed in contact with the back surface 12 of the lens.

This is because the incident light 16 is always reflected on the back surface of the lens, which is perpendicular to the direction of incidence, and due to the action of the mirror surface, one reflected light has the maximum intensity in the direction of incidence, that is, the reflected light component and the transmitted light component are combined. A scattering intensity distribution 25 is obtained, and the brightness of one image is improved.

The reflection characteristics in this case are shown in FIG. 5. As can be seen in the graph 33 of the light beam incident from a position perpendicular to the lens surface 11, the graph 34 of the 80 degree incidence, and the graph 35 of the 70 degree incidence, the conventional lenticular lens There is an effect that the reflected light returns to the direction of incidence of the light ray not only when the light ray enters the lens surface from a position perpendicular to the lens surface, but also at other angles.

FIG. 6 shows a cross-sectional view of a lenticular lens according to still another embodiment of the present invention, in which the radius of curvature r of the back surface 12 of the lens is larger at the center portion 36 than at the left and right peripheral portions 37, as shown in FIG.
．． It is made smaller continuously (or stepwise) as it goes to 38. Others, diffusion layer 3. Providing the mirror surface 24 is as described above.

When an image is projected onto the lenticular screen in such a configuration, the projection angle θ is small in the center, so the reflected light returns to the incident direction even though the radius of curvature r of the back surface of the lenticular lens is large, and even in the peripheral region, the reflected light returns to the incident direction. Since the radius of curvature r is small, there is an effect that the reflected light returns to the incident direction even though the projection angle θ is large.

This has the feature that the reflection intensity distribution can be arbitrarily set by arbitrarily setting the rate at which the radius of curvature changes. Further, even if the radius of curvature is infinite (ie, flat) at the center, there is no problem in operation. (Effects of the Invention) Since the present invention is configured as explained above, the brightness of the image is significantly improved in the center, left and right peripheral areas of the lenticular screen, and the projection position and m-viewing position are also fixed at one location. Even if you don't.

It is possible to display three-dimensional images.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a lenticular lens according to an embodiment of the present invention, FIG. 2 is a reflection characteristic diagram of the embodiment of FIG. 1 and a conventional lenticular lens, and FIG. 3 is a lenticular lens according to another embodiment of the present invention. 4 is a cross-sectional view of the lens, FIG. 4 is a lenticular lens used in FIG. 3, FIG. 5 is a reflection characteristic diagram of the lenticular lens in FIG. 3, and FIG. 6 is a cross-sectional view of a lenticular lens according to still another embodiment of the present invention. Fig. 7 is an explanatory diagram of the back side of the lenticular lens used in Fig. 6, Fig. 8 is a perspective external view of an example of a conventional lenticular lens, and Fig. 9 is a tertiary lens using the lenticular lens shown in Fig. 8. An example of how to display an original image. Figure 10 is a state diagram of the brightness distribution according to Figure 9. Figure 11 is a reflection characteristic diagram depending on the incident angle to a conventional lenticular lens. Figure 12 is a diagram of the incident light on a lenticular lens. An explanatory diagram of reflected light and transmitted light, Fig. 13 is an explanatory diagram of the scattering intensity distribution by the diffusion layer, and Fig. 14 is an explanatory diagram of the scattered light distribution by the diffusion layer.
FIG. 3 is an explanatory diagram of the operation of a conventional lenticular lens, summarizing the operations of FIG. 1... Lenticular lens, 2... Lens body, 3... Diffusion layer, 4... i observer. 5... Projector, 6... Center of lens, 7...
・・Brightness distribution, 8～10.26.27.33～35・
... Reflection characteristics graph, 11... Lens surface, 12.
...Lens back surface, 13.16...Incoming light, 14.18
...Reflected light, 15... Transmission direction, 17... Reflective surface, 19... Transmitted light, 20... Right angle line, 21...
Normal line, 22...Scattered intensity distribution in the reflection direction, 23...
Scattered intensity distribution in the transmission direction, 24... mirror surface, 25...
Combined scattering intensity distribution, 28...Central center point, 2
9... Radius, 30... Focal length, 31, 32...
Pitch, 36...center, 37°38...periphery. Patent applicant: Nippon Telegraph and Telephone Corporation Figure 4 Figure 6 Figure 7 3A is so gold lol, several pages (B) 3B and 41 Sawa spread all over

Claims (1)

[Claims] In a reflective lenticular screen that projects an image onto a lenticular screen using a projector and views the reflected image stereoscopically, a mirror surface is placed in contact with the back surface of a diffusion layer provided on the back surface of the lenticular lens, and A reflective lenticular screen characterized by having a cross-sectional shape that is flat or arcuate with curvature.