JPS63265235A - Transmissive projecting screen - Google Patents

Abstract

PURPOSE:To make a horizontal visual field angle wide, to reduce color shifts and to make it easy to reduce the reflection of external light beam by arranging a prescribed first lens plate and a prescribed second lens plate. CONSTITUTION:The first lens plate 2 having a Fresnel lens 4 at least on one side is arranged on an incidence side and the second lens plate 3 forming lenticular lenses 5 and 6 consisting of main lenticular lenses L1 and L4 and sub lenticular lenses L2, L3, L5 and L6 provided on both sides of L1 and L4 on both surfaces are arranged on radiation side. The second lens plate 3 diffuses an incident light in wider range so as to equally radiate the projected light in all parts of a screen. Since the second lens plate can adjust the rate of light entering into the main lenticular lenses and the sub lenticular lenses on the incidence side and the radiation side according to the rate of the sizes of lenses, horizontal diffusion characteristic can be freely set and moreover the incident light beam with different incident angles can be diffused in a nearly same direction according to the shapes of four lenses, so that the color shifts can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a so-called transmission type in which an image is projected from the back side and observed from the front side, and has little color shift and high contrast. The present invention relates to a transmission projection screen.

[Prior Art and Problems to be Solved by the Invention] Hitherto, transmission type projection screens for viewing images by projecting from the back side have been known, and various configurations have been proposed. Particularly in recent years, transmissive screens used in color television projectors have the inherent function of diffusing light toward the viewing side, but at the same time, this phenomenon occurs due to the colors red, green, and blue being projected from different positions. Color television projectors require a function to correct color shift, and the brightness is not very high because it is difficult to improve the brightness. Since it reduces the contrast of the image and impairs visibility, it is required to reduce the reflection of external light.

An example of a material that satisfies the above requirements is a black stripe, in which groups of lenticular lenses are provided on both sides of the sheet and correspond to each other in the same direction, and a light-shielding layer of black or other color is provided on the part of the exit surface where no light is emitted. Double-sided lenticular lens sheets are known.

However, the double-sided lenticular lens sheet with black stripes described above has the disadvantage that the horizontal viewing angle is limited to a narrow range of about 30'' on either side of the optical axis, or 60'' in total. On the other hand, in order to widen the viewing angle in the horizontal direction, there are also known transmissive screens that completely reflect part of the light that enters the screen on a part of the screen and then emit it. In this case, the color shift is large because the screen does not include an element to correct the color shift, and in order to reduce the reflection of external light, it is necessary to provide a light shielding layer on the non-light emitting surface of the light emitting surface. , since the non-light-emitting surface is a total reflection surface,
A light-shielding layer must be provided on the total reflection surface, but this
It is very difficult to provide a reflective layer on the total reflection surface and a light shielding layer thereon, and (2) to form such a layer on the concave portion.

[Means for solving problems]

The present invention has been made in view of the above points, and it is an object of the present invention to provide a transmission type projection screen that has a wide horizontal viewing angle, has little color shift, and can easily reduce the reflection of external light.

That is, in the present invention, a first lens plate having a Fresnel lens formed on at least one side is arranged on the light incidence side, and lenticular lenses corresponding to each other and having the same light diffusion direction on both sides are disposed on the light emission side. The lenticular lenses on the entrance side include a main lenticular lens on the entrance side that receives most of the incident light, and one lens on each side of each main lenticular lens on the entrance side that receives the remaining part of the incident light. The lenticular lens on the exit side is composed of a secondary lenticular lens on the input side through which light enters, a main lenticular lens on the output side that outputs the light that entered the main lenticular lens on the input side, and 1 lenticular lens on both sides of each main lenticular lens on the output side. The main feature of this invention is a transmissive projection screen characterized in that a second lens plate is arranged, each of which has a secondary lenticular lens on the incident side and an auxiliary lenticular lens on the output side that emits light that has entered the auxiliary lenticular lens on the input side. be.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

As shown in FIG. 1, the transmission type projection screen 1 of the present invention includes a first lens plate 2 disposed on the light incident side (left side in the figure);
It consists of a second lens plate 3 arranged on the light exit side (right side in the figure). The first temporary lens 2 has a structure in which a Fresnel lens is formed on at least one surface, and in the embodiment shown in FIG. 1, a circular Fresnel lens 4 is provided on the exit side surface of the first lens plate 2. .

The second lens plate 3 is provided with lenticular lenses 5 and 6 that correspond to each other in the same light diffusion direction (normally, the light diffusion direction is set in the horizontal direction) on both sides, and the lenticular lenses 5 and 6 on the incident surface side 5 is a main lenticular lens L on the entrance side that occupies most of the entrance surface as shown in FIG.
, and entrance side lenticular lenses Lx and L occupying the remaining part of the entrance surface. Lenses L1 and L are arranged one each in contact with both sides of lens L.

Also, the relationship between the sizes of the main lenticular lens L and the secondary lenticular lens L is determined by the width of lens L2 (length between AB) and the width of lens L (length between CD). The ratio of sum: lens L, width (length between b and c) is 1:9 ~
A ratio of 4:6 is preferable, so that 90 to 60% of the incident light is received by the lens L1, and the remaining 10 to 40% is received by the lens L1.
% is held between lens L3 and lens L and is incident.

The lenticular lens 6 on the exit surface side also includes a main lenticular lens L on the entrance side, an upper lenticular lens L O on the exit side that outputs the light incident on the entrance side, and auxiliary lenticular lenses on the entrance side arranged on both sides thereof.

It is composed of output-side secondary lenticular lenses LS and L& that output the light incident on L and L, respectively.

The size relationship between the exit side main lenticular lens L4 and the secondary lenticular lenses L and L6 corresponds to the size relationship between the input side main lenticular lens L and the secondary lenticular lenses L2 and L6. However, since the light refracted by the lens L is focused by the lens L4, the width of the lens L4 may be smaller than the width of the lens.

In the second lens plate 3 configured as described above, the lens pitch P (length between ab and ab) and the thickness t vary depending on the overall size of the lens plate 2 or the distance from the observer. Assuming a television screen of 40 inches or larger, P = 0.3 to 1.5, and t = 0.3 to 1.
Approximately 5fi is preferable.

FIG. 2 shows a state in which a ray of light that is incident parallel to the optical axis 7 is refracted and emitted from the second lens plate 3, and a ray of light between a and b is incident on lenses t and z, and between b and % C. The rays of light enter the lens L, and the rays of light between 0 and 4 enter the lens L3.

First, the light beam between b and c is refracted by lenses L and L4 and then emitted. The emitting range is lens L.

The shapes of the lenses L and L# can be changed depending on the shapes of the lenses L4 and L4, but the shapes of the lenses L and L# are circles, ellipses, parts of parabolas, or other curves. In the case of this figure, the lens L# is a part of an ellipse with major axis: minor axis = 1: 0.733, and the lens L# is a part of an ellipse with major axis: minor axis - 1: 0.655, and the light is , ± with respect to the normal perpendicular to this second lens plate
It is emitted in a range of 49°. The light is emitted within a range of ±49", but as the angle increases, the amount of emitted light decreases, so the observable range with this emitted light is practically ±3".
It will be about 0°.

Next, the light entering the ranges ab and c w d is refracted by lenses Lt and L, and lenses L3 and L&, respectively, and exits. In this case as well, lenses I, t
Although the emitted range varies depending on the shape of lens L3, lens Ls, and lens L&, basically, the light rays incident from lens L2 and lens L3, respectively, are refracted toward the optical axis 7 of lens L. The light then reaches the lenses L1 and L, and is further refracted by the lenses LS and L toward the optical axis 7 of the lens L. The shape of the lens L2% lens L3 and the lens LS% lens L6 that perform such an action is a circle, an ellipse, a part of a parabola, or another curved line. In this figure, lens L2 is the major axis of the lens.
Short diameter = 1: Lens a part of the 0.512 ellipse 1
, lens L6 is a part of a circle, and the light is +32°~+63°
'' and is emitted in the range of -32'' to -63°.

In this way, the second lens plate 3 has an entrance surface and an exit surface each composed of two types of lenticular lenses, a main lenticular lens and a sub-lenticular lens. The viewing angle can be widened compared to the previous one.

The horizontal diffusivity of the emitted light in the second lens plate 3 changes depending on the shape of each lens, and also depends on the proportion of light incident on the upper incident side and the sub lenticular lens, that is, the ratio of the sizes of the main lenticular lens and the sub lenticular lens. can also be changed. Therefore, with the second lens plate 3 used in the present invention, it is possible to brighten the viewing angle near 0'', and it is also possible to brighten the area from about 30° to 50°, and this is usually considered the most desirable. However, it is also possible to make an area of about 0 to 50 inches uniform in brightness. In the case of Figure 2, the ratio of light entering the main lenticule on the incident side and the sub-lenticular is 1:0.23, and the output area of each is as shown above, so it is approximately uniform from 00 to 45 degrees. Light is emitted from the

Further, it is known that color shift can be reduced in a double-sided lenticular lens plate by appropriately designing lenticular lenses on the incident side and the output side. In principle, if the exit surface is made into a circle or part of an ellipse, the light that exits from a position far from the center of the lens will be refracted inward, so the incident angle This is because when light with different values enters the double-sided lenticular lens, the distribution of the output light becomes quite similar.

In the present invention, the color shift of the emitted light due to the main lenticular lens on the entrance side and the lenticular lens on the exit side can be similarly reduced by appropriately designing the lenticular lenses on the entrance side and the exit side of the second lens plate 3. . Moreover, since the principle is as described above, the color shift can be reduced by designing the sub-lenticular lens in a similar manner. Therefore, the second lens plate 3 used in the present invention can reduce the color shift of the entire output light.

A light-shielding layer 8 can be provided on the non-light-emitting portion of the exit-side lenticular lens 6 of the second lens plate 3 as required. By providing the light-shielding layer 8, a high-contrast screen with little loss of contrast even in a bright room can be created. can be easily done.

The light-shielding layer 8 may be provided by known methods such as printing, coating, and transfer, and the light-shielding layer itself is made of a composition having light-shielding and light-absorbing properties, such as a known paint or ink with a black pigment and the like. Preferably, one to which a matting agent is added may be used.

In particular, as shown in FIG. 3, if the portion where the light shielding N8 is provided is formed as a convex portion 9 with a flat surface during lens plate molding, and the light shielding layer 8 is formed on top of this, it can be formed by printing, coating, or transfer. This is preferable because the formation of the light shielding layer 8 becomes easier.

The screen 1 of the present invention has a second lens plate 3 having a circular Fresnel lens 4 on the exit surface side, and a lenticular lens 10 for vertical diffusion on the entrance surface side to widen the vertical viewing angle (FIG. 4). By providing a vertical optical axis refracting prism 11 (FIG. 5), the vertical field of view can be displaced upward or downward.

Although not particularly shown, the first lens plate may have a configuration in which a vertical linear Fresnel lens is provided on one surface and a horizontal linear Fresnel lens is provided on the other surface. 1 lens plate, 2ji vertical linear Fresnel lens plate and horizontal linear Fresnel lens plate
In the case of a # lens plate, a lenticular lens for vertical diffusion is formed on the Fresnel lens-free surface of the vertical linear Fresnel lens plate and/or the Fresnel lens-free surface of the horizontal linear Fresnel lens plate, and the vertical viewing angle is For example, as shown in FIG. 6, a vertical linear Fresnel lens 12 is provided on the incident surface side, and a lenticular lens 1 for vertical diffusion is provided on the exit surface side.
3, and the first lens plate 2 can be configured by a water lens plate on the exit surface side.

In order to further increase the vertical diffusion, the first lens plate 2 and the second
A lenticular lens plate 17 for vertical diffusion may be disposed between the first lens plate 3 (FIG. 7), or a lenticular lens plate 17 for vertical diffusion may be disposed on the incident surface side of the first lens plate 2.

Further, in order to improve the light diffusivity, the second lens plate 3 may contain a light diffusing material, or the surface of the lenticular lens on the exit surface side of the second lens plate 3 may be formed with fine irregularities for light diffusion. As the light diffusing material, extender pigments such as finely powdered silica and finely powdered alumina, glass powder, resin powder, etc. are used, and the particle size of these is preferably about 0.5 to 30μ, and usually 0.5 to 30μ in the lens plate. 5% by weight is added. The light diffusing fine irregularities are formed by roughening the surface by sandblasting or the like.

The projection screen of the present invention may be made of any material as long as it is transparent and can be formed into a sheet, including acrylic resins such as polymethyl methacrylate, polyester resins, cellulose resins, polyvinyl chloride resins,
Thermoplastic resins such as polystyrene resins and polycarbonate resins, or glass are preferred. Among them, thermoplastic resins can be easily and efficiently manufactured by known molding methods. There is a method in which a sheet of thermoplastic resin is heated and pressurized using an inverted mold (plate-like or roll-like) of a predetermined shape, and a method in which a sheet of thermoplastic resin is heated and pressurized immediately after the sheet is manufactured, while the sheet is still cooled. How to do something to something that doesn't exist,
Alternatively, casting using a metal mold or other molding methods are suitable when the lens sheet is made of thermoplastic resin. Depending on the mold, the size of the lens sheet, etc., the thermoplastic resin sheet may be cut into pieces and then processed.
A continuous sheet, such as a roll, may be continuously processed.

〔Effect of the invention〕

In the transmission type projection screen of the present invention, a first lens plate having a Fresnel lens on at least one side is arranged on the incident side, and a lenticular lens consisting of a main lenticular lens and sub-lenticular lenses provided on both sides of the main lenticular lens on the exit side is arranged on both sides. The second lens plate used in the present invention can diffuse incident light over a wider range than conventional double-sided lenticular lenses. By combining with one lens plate, projection light can be uniformly irradiated to every corner of the screen. In addition, the second lens plate has horizontal diffusion properties that can brighten a specific part of the viewing angle because the ratio of light that enters the main lenticular lens and the sub lenticular lens on the entrance and exit sides can be adjusted by adjusting the ratio of the lens sizes. can be set freely, and the four lens shapes of the main lenticular lens and the secondary lenticular lens on the input and output sides allow light incident at different angles of incidence to be diffused in almost the same direction, resulting in color shift. This has various effects such as being able to reduce the

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a plan cross-sectional view of one embodiment of the transmission type projection screen of the present invention, and FIG.
FIG. 3 is a plan sectional view showing another embodiment of the screen of the present invention, and FIGS. 4 to 8 are longitudinal sectional views showing still other embodiments. It is. 1... Transmissive projection screen 2... Second lens plate 3... Second lens plate 4... Circular-lenticular lens 5... Entrance side lenticular lens 6... Output side lenticular lens L, ...Incidence side main lenticular lens 1, t, 1
．． 1... Input side secondary lenticular lens L4... Output side main lenticular lens L5. L6... Output side secondary lenticular lens 12... Vertical linear Fresnel lens 15... Horizontal linear Fresnel lens 1°! Figure 3 Figure 4 Figure 5 Figure 7 Figure 8

Claims (12)

[Claims] (1) A first lens plate formed with a Fresnel lens on at least one side is arranged on the light incidence side, and a first lens plate formed with a Fresnel lens on at least one side is arranged, and on the light output side,
Lenticular lenses that have the same light diffusion direction and correspond to each other are provided on both sides, and the lenticular lens on the entrance surface side is connected to the main lenticular lens on the entrance side that receives most of the incident light, and the main lenticular lens on the entrance side that receives most of the incident light. It consists of a secondary lenticular lens on the input side, one on each side, which receives the remaining part of the incident light, and a lenticular lens on the output side that outputs the light that entered the main lenticular lens on the input side. A second lens plate is arranged, which consists of a side main lenticular lens and an output side secondary lenticular lens, which is placed one on each side of each output side main lenticular lens and outputs the light that has entered the input side secondary lenticular lens. A transparent projection screen that is characterized by: (2) The transmission type projection screen according to claim 1, wherein a circular Fresnel lens is formed on the exit surface side of the first lens plate, and a vertical diffusion lenticular lens is formed on the entrance surface side. (3) The transmission type projection screen according to claim 1, wherein a circular Fresnel lens is formed on the exit surface side of the first lens plate, and a vertical optical axis refracting prism is formed on the entrance surface side. (4) The transmission type projection screen according to claim 1, wherein a vertical linear Fresnel lens is provided on one surface of the first lens plate, and a horizontal linear Fresnel lens is provided on the other surface. (5) the first lens plate is a vertical linear Fresnel lens plate;
A transmission type projection screen according to claim 1, comprising two horizontal linear Fresnel lens plates. (6) A lenticular lens for vertical diffusion is formed on the linear Fresnel lens non-forming surface of the horizontal linear Fresnel lens plate and/or the linear Fresnel lens non-forming surface of the vertical linear Fresnel lens plate. Transparent projection screen. (7) A light shielding layer is provided in the non-light emitting portion of the lenticular lens on the exit surface side of the second lens plate.
The transmission type projection screen according to any one of Items 1 to 6. (8) A transmission type according to any one of claims 1 to 6, wherein a convex portion having a light shielding layer formed thereon is provided on a non-light emitting portion of the lenticular lens on the exit surface side of the second lens plate. projection screen. (9) The transmission type projection screen according to any one of claims 1 to 8, wherein a lenticular lens plate for vertical diffusion is disposed between the first lens plate and the second lens plate. (10) The transmission type projection screen according to any one of claims 1 to 8, wherein a lenticular lens plate for vertical diffusion is disposed on the incident surface side of the first lens plate. (11) The transmission type projection screen according to any one of claims 1 to 10, wherein the second lens plate contains a light diffusing material. (12) The transmission type projection screen according to any one of claims 1 to 10, wherein fine irregularities for light diffusion are formed on the surface of the lenticular lens on the exit surface side of the second lens plate.