JPH0496041A - Projecting screen - Google Patents

Abstract

PURPOSE:To allow the equal observation of high-brightness videos in a wide angle range covering the range between both ends of a stand by constituting the bead screen of microglass spheres which vary in refractive index and are mingled with each other. CONSTITUTION:A glass bead layer 4 consists of substantially one layer of the aggregate layer in which 1st glass beads 41A made of, for example, crown glass having about 0.5mm spherical diameter and about 1.5 index and 2nd glass beads 41B made of high-refractive glass having about 0.5mm spherical diameter and about 1.93 index are nearly uniformly and demely dispersed and distributed in the respective parts at 2:1 ratio by the number of grains. This reflection type screen has a wide diffusion angle with the directivity of the reflected light exhibiting respectively 30 deg. on the right and left. The high-brightness videos of the brightness nearly equal in the central part of this diffusion angle and in the respective parts of the entire diffusion angle of 30 deg. on the right and left are observed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a reflective (front type) or transmissive (rear type) projection screen in a projection system such as a video projector, movie projector, magic lantern, or the like.

More specifically, the present invention relates to a projection screen (hereinafter referred to as a bead screen) in which a projection light reflecting surface or a projection light transmitting layer is an aggregate surface or an aggregate layer of micro glass beads (hereinafter referred to as glass beads).

(Prior Art) Reflective or transmissive bead screens as described above are already known.

FIG. 5 shows a cross-sectional model diagram showing the layer structure of an example of a reflective bead screen.

1 is a bead screen fabric, which includes a white base sheet 2 such as a white vinyl chloride sheet as a fabric base, and an adhesive such as vinyl acetate based adhesive coated on the surface of the base sheet 2 to a thickness of several μm. It consists of a layer 3 and a glass bead layer 4 formed by dispersing micro glass beads 41 uniformly and at high density on each surface of the adhesive layer 3 and fixing them to the surface of the base sheet 2 via the adhesive layer 3. . 5 and 6 are the back side of the above bead screen fabric 1,
That is, a class fiber cloth layer as a backing material layer and a resin sheet layer made of vinyl chloride or the like are laminated in sequence on the back surface of the base sheet 2. The backing material layers 5 and 6 serve to ensure the strength and dimensional stability of the entire screen. It is also black to provide light shielding properties.

The individual glass beads 41 constituting the glass bead layer 4 are substantially spherical transparent glass microspheres, for example, having a diameter of several tens of micrometers to several hundreds of micrometers, and are uniformly scattered on the surface of the white base 2 to form a fixed glass bead layer. 4 is substantially one layer of densely distributed aggregated layers of the glass beads 41.

Then, an optical image is formed and projected onto the surface of the screen on the glass beads layer 4 side, and the reflected image is viewed.

Compared to non-bead-based screens, such as non-bead-based screens, such as dull white screens with fine uneven wrinkles on the surface, these reflective bead screens have a higher reflection efficiency for projection light and can produce high-brightness images. Furthermore, it realizes images with high fidelity color reproducibility and gradation, and is suitable for, for example, the projection screen of a large-screen video projector.

FIG. 6 shows a cross-sectional model diagram showing the layer structure of an example of a transmission type bead screen.

7 is a transparent base material layer, which ensures the strength and dimensional stability of the entire screen, and is made of a transparent resin sheet or plate material of an appropriate thickness such as soft or hard vinyl chloride resin or acrylic resin. Can be used.

8 is a transparent adhesive layer that is thinly coated on the surface of the transparent base material layer 7, and 4 is an adhesive layer in which the same minute crow pieces 41 as described above are evenly distributed on the surface of the adhesive layer 8 at a high density. This is a glass dosing layer formed by adhering to the surface of the transparent base material 7 via 8. This crow beads layer 4 is substantially one layer of densely distributed crow beads 41.

9 exposes the gap space between the individual crow beads 41 of the crow bead layer 4 on the top surface side opposite to the bottom surface side in contact with the transparent adhesive layer 8 of the individual crow beads 41. This is a layer of light-shielding material that is filled with For example, by using black toner used as a developer in electrophotographic copying machines, the toner is applied to the glass dosing layer 4 which is fixed to the surface of the transparent base material layer 7 via the transparent adhesive layer 8. Rub it into the surface and embed it in the gap space between the individual glass beads 41, and remove the excess toner and apply it to the top surface of the individual glass beads 41 opposite to the bottom surface that is in contact with the transparent adhesive layer 8. Leave it exposed. The rubbed toner, which serves as a light-shielding material layer that fills the gaps between the individual crows 41, is solidified by heat treatment or the like, if necessary.

In principle, the above-mentioned screen projects an image with the transparent base material layer 7 side as the back side of the screen, and the image is viewed on the opposite side, that is, the glass dosing layer 4 side (the front side of the screen). The image light directed to the surface of the transparent base material layer 7 is transmitted from the transparent base material layer 7 → the transparent adhesive layer 8 → the bottom surface of the individual glass beads 41 in contact with the transparent adhesive layer 8 → the individual glass beads 4
1 → Externally exposed top surface of each crow bead 41, exits to the screen surface side through a path. and individual crow beads 4
It acts as a light diffusing agent and functions as a transmission screen.

Such a transmission type bead screen is a non-bead-based screen, - a numerically translucent light-diffusing transmission screen, that is, a transparent resin such as acrylic resin or vinyl chloride resin is used as the base material (binder material). Compared to an entirely translucent fleshy screen made by blending and dispersing a light diffusing agent such as mica powder or silicon compound powder, the amount of light transmitted through the screen is significantly increased, resulting in a screen gain (screen (image) Brightness) is improved, and image contrast, resolution, color reproducibility, gradation, etc. are also improved.

(Problems to be Solved by the Invention) In the conventional reflective or transmissive bead screen of this type, the individual glass beads 41 constituting the glass dosing layer 4
They were constructed using a single type of ball with substantially uniform refractive index (relative refractive index with respect to air, hereinafter referred to as index) and spherical diameter.

In this case, depending on the index of the glass beads 41, the range in which the light reflected from the screen surface or the light transmitted through the screen is diffused (diffusion angle or directivity; the light reflected from the screen surface or the light transmitted through the screen surface is centered around an axis perpendicular to the screen surface) Since the angular range of diffusion to the left and right sides is determined,
When the index of the glass beads 41 used to obtain a high-brightness image is set to a high value by intensively transmitting reflected or transmitted light of the projection light to the audience seats, the diffusion angle becomes narrower and screen surface reflection occurs. Even though the light or screen-transmitted light is directed toward the center of the audience seats, and a high-intensity image is observed at the center of the audience seats, the brightness of the image observed at both ends of the audience seats is reduced.

Therefore, so that a high-intensity image can be observed at both ends of the audience seats, the index of the glass beads 41 used is set to a low value (for example, 1.6 or less) and the diffusion angle is widened (for example, 3.0o for each of the left and right sides). The brightness of the image observed decreases in the center of the seat.

In other words, in the case of a conventional reflective or transmissive bead screen constructed using a single type of glass beads 41 that are substantially uniform in index and spherical diameter, the index of the glass beads 41 used is selected. With bamboo, it is difficult to obtain a system that allows viewing of high-brightness images equally in each part of the wide diffusion angle range that covers both ends of the audience seats.

The present invention is also a bead screen, but it is an object of the present invention to provide a bead screen that solves the above-mentioned problems (means for solving the problems). A projection screen with a collective surface or a collective layer of micro glass spheres, characterized in that the collective surface or collective layer of micro glass spheres is composed of a mixture of two or more types of micro glass spheres having different relative refractive indexes with respect to air. It is a projection screen.

The present invention also provides a projection screen as described above, in which two or more types of microscopic vitreous spheres having different relative refractive indexes with respect to air have substantially the same sphere diameter or at least one type is different from the others. This is a projection screen that is characterized by:

(Function) That is, if the aggregate surface or aggregate layer of micro vitreous spheres (glass beads) is composed of a mixture of two or more types of micro vitreous spheres having different relative refractive indexes with respect to air,
Diffusion angles are multiplexed (directivity multiplexed) due to differences in diffusion angles between the mixed plurality of micro glass spheres having different refractive indexes.

Therefore, by appropriately arranging the mixing ratio of two or more types of microscopic glass spheres with different refractive indexes, the bead screen allows viewing equally high-brightness images in each part over a wide angular range that covers both ends of the audience seats. type of projection screen (multi-directional reflective or transmissive projection screen).

(Example) <Example 1> A1 sphere diameter (average sphere diameter) approximately 0.5 mm Index approximately 1.5, for example, first crow beads made of crown glass 41A0 B1 sphere diameter approximately 0.5 ma+ The second glass beads 41B6 are made of high refractive glass with a degree index of approximately 1.93.The first and second sphere diameters are approximately the same, but the indexes are different from each other as described above. Seeds of glass peas 41A and 41B were uniformly mixed at a grain number ratio of 2:1.

Thus, a screen was prepared in which the above-mentioned mixed glass beads 41A and 41B were used as the glass beads constituting the glass bead layer 4, and the other configuration was the same as that of the reflective bead screen shown in the example shown in FIG.

FIG. 1 shows a cross-sectional model diagram showing the layer structure of this screen. In the glass bead layer 4, first and second glass beads 41A and 41B having different indexes have a grain number ratio of 2.
:1, each part is substantially a single layer of aggregated layer dispersed and distributed almost uniformly and with high density.

The reflective screen of this embodiment has a wide diffusion angle, with the directivity of the reflected light showing 30 degrees to the left and right, as shown by the solid graph line (■) in the reflection characteristic diagram in Figure 2, and the center of the diffusion angle. A high-intensity image with approximately equal brightness was observed at each part of the entire diffusion angle of 30° left and right.

For reference, here is a reflective bead screen in which the glass bead layer 4 is formed using only the first glass beads 41A with an index of about 1.5 and only the second glass beads 41B with an index of about 1.93. Each reflection characteristic is shown in FIG. 2 by a one-dot chain line graph (■) and a two-dot chain line graph (■).

<Example 2> C1 sphere diameter (average sphere diameter) approximately 0.5 mm Index approximately 1.6 For example, first glass beads made of heavy flint glass 41C009 sphere diameter approximately 0.2 mm Index approximately 1 The second glass beads 41D0 are made of high refractive glass of about .98. The glass beads layer 4 is constructed in the following manner using the first and second two types of glass beads 41C and 41D.
Other than that, a reflective bead screen having the same structure as the reflective bead screen shown in the example shown in FIG. 5 was prepared.

To create the glass bead layer 4, after coating the surface of the base sheet 2 with the adhesive layer 3, first glass beads 41C with a larger spherical diameter are sprinkled, excess beads are removed, and then the first glass beads 41C with a smaller spherical diameter are sprinkled. 2. Sprinkle glass beads 41D and remove excess beads. After the adhesive layer 3 dries, the surface of the formed glass beads layer is lightly pressurized.

FIG. 3 shows a cross-sectional model diagram showing the layer structure of this screen. The glass bead layer 4 includes second glass beads 41 with a small spherical diameter between the first glass beads 41C with a large spherical diameter.
D enters and the first and second glass doors 41C and 41
Each part of D is substantially a single layer of aggregated layers that are uniformly and densely distributed. First and second glass beads 41C/4
The distribution ratio of 1D is approximately 1:1 to 1:2 in grain number ratio.

The reflective screen of this example has a wider directivity than that of the first example described above, as shown by the solid line graph (■) in the reflection characteristic diagram of FIG. A high-brightness image with approximately equal brightness was observed at each part of the entire diffusion angle.

For reference, each reflection characteristic of a reflective screen in which the glass bead layer 4 is formed using the first crow beads 41C and the second glass beads 41D is shown in a dash-dotted line graph in FIG. It is shown by ■ and a two-dot chain line graph ■.

A screen having desired reflection characteristics as a whole can be constructed by combining three or more types of glass layers with different indexes and sphere diameters in appropriate proportions and multiplexing the directivity of each of these beads.

Although omitted as an example, even for transmission-type glass beads such as the example shown in FIG. Accordingly, based on the same theory, it is possible to construct an apparatus that has a wide diffusion angle and allows viewing of an almost uniform high-luminance image in each part of the full-angle range.

The glass beads 41A, 41B, 41C, and 41D also include transparent resin beads with different indexes.

(Effects of the Invention) As described above, according to the present invention, the aggregate surface or aggregate layer of the micro vitreous spheres in the bead screen is composed of a mixture of two or more types of micro vitreous spheres having different refractive indexes. By appropriately arranging the mixture ratio, a bead screen type projection screen (multi-directional reflective type or transmissive type) can be used to display high-brightness images equally in each part over a wide angle range that covers both ends of the audience seats. It becomes possible to construct a projection screen).

[Brief explanation of drawings]

FIG. 1 is a cross-sectional model diagram showing the layer structure of the bead screen of the first embodiment. Figure 2 shows the reflection characteristics of the screen. FIG. 3 is a cross-sectional model diagram showing the layer structure of the bead screen of the second embodiment. Figure 4 shows the reflection characteristics of the screen. Figures 5 and 6 are cross-sectional model diagrams showing the layer configurations of reflective and transmissive bead screens, respectively. 4 is a glass bead layer, 41, 41A, 41B, 41C,
41D is crow beads.

Claims (2)

[Claims] (1) In a projection screen in which the projection light reflecting surface or the projection light transmitting layer is an aggregate surface or an aggregate layer of micro glass spheres,
A projection screen characterized in that the aggregate surface or aggregate layer of the micro glass spheres is composed of a mixture of two or more types of micro glass spheres having different relative refractive indexes with respect to air. (2) The two or more types of microscopic vitreous spheres having different relative refractive indexes with respect to air have substantially the same spherical diameter, or at least one type has a different spherical diameter from the others. projection screen.