JP3318378B2 - Reflective screen - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective screen for projecting a projected image, and more particularly to a reflective screen useful for sharpening a projected image emitted from a liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal display devices have advantages such as small size, light weight, and non-pollutability of waste products as compared with CRT display devices, and are highly evaluated for their future potential. Because of insufficient brightness when projected on a screen, it is necessary to view images in a dark room where external light is blocked. Focusing on the fact that the projected light emitted from the liquid crystal display device is linearly polarized light, while the external light that impairs the sharpness of the projected image is usually unpolarized, and only the external light is removed on the screen. It is expected that the projected image will be clearly visible even in a bright environment. For example, Japanese Patent Application Laid-Open
In the inventions of Japanese Patent Application Publication No. 266980 and Japanese Patent Application Laid-Open No. Sho 64-77085, reflection of non-polarizing extraneous light is achieved by mounting a light absorbing polarizing film oriented in a direction transmitting linearly polarized projection light on the surface of the screen. Methods for reducing the amount have been proposed. Japanese Patent Application Laid-Open No. 2-267536 discloses a method of sharpening a linearly polarized projection image by covering an illumination light source with a light absorption type polarizing filter oriented in a direction orthogonal to a polarizing filter on a screen. Proposed.

[0003]

However, in a bright environment, it is not enough to clear a linearly polarized projected image by simply removing non-polarized external light, and the following problems can be solved. It costs.

In a liquid crystal display device, a light source is used because a video signal is reproduced using a light absorption type polarizing filter and a TFT (thin film transistor) interferes with transmission of signal light and has a low aperture ratio. Light use efficiency is low.
Therefore, in order to clearly view the projected image emitted from the liquid crystal display device on the screen, a structure that uniformly reflects the projection light only within the reflection angle (viewing angle) required for viewing the image is provided by a reflector of the screen. Therefore, it is extremely important to effectively use the light from the light source.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to make it possible to reflect projection light as much as possible within a reflection angle required for viewing an image and to reduce reflected light as much as possible. It is an object of the present invention to provide a reflective screen that can be made uniform.

[0006]

A configuration of the present invention for achieving the above object will be described with reference to FIG. In FIG. 1, in a reflection type screen provided with a polarizing member 2 that transmits light having a first polarization direction D1 and absorbs light having a second polarization direction D2 perpendicular thereto, first, a polarizing fiber The polarizing member 2 is formed by arranging a large number of 1s in parallel with each other along the second polarization direction D2 and periodically changing the diameter of the polarizing fiber 1. Surface 1a of polarizing fiber 1
The transparent resin layer 13 is provided on the concave portion 1 between the polarizing fibers 1.
Then, the reflective surface 14 is formed on the surface 13a of the resin layer 13 by filling the space b.

In this case, as shown in FIG. 6, the polarizing member 2 comprises a non-polarizing fiber 1 extending in a first polarization direction D1.
5, it is preferable that the polarizing fiber 1 is knitted.

[0008]

Next, the principle of the present invention will be described. In order to achieve both sharpness of the projected image and the function of winding the screen, it is desirable to enhance the viewing efficiency of the projection light without the screen being curved. Generally, the projection light of the liquid crystal display device is a spherical wave, which is projected in a conical manner with respect to the reference plane of the screen. However, when the magnification is small, the projection light 5 can be regarded as a plane wave projected perpendicularly to the reference plane 50 of the screen as shown in FIG. Here, the viewing half-value angle (reflection half-value angle) T (where T> 0) facing the observer (the liquid crystal display device side) from the surface of the reflector of the screen is divided into n equal parts, and the n unit reflecting surfaces are used. A reflective section 51 made of
Are connected (repeated) over the entire area of the reference surface 50 of the screen, thereby forming the reflection surface 52 having a periodic sectional shape. In each of the reflection sections 51, the coordinates in the reference plane (r-axis) direction are represented by the following equation (1), and the coordinates in the normal direction (z-axis) direction of the reference plane are described in (2) below.
It is given by the equation or the equation (3). In addition, 53 is a normal to the reflecting surface, 54 is reflected light, and ζ is
This is a constant given by equation (4).

[0009]

(Equation 1)

By providing an uneven structure having such a cross-sectional shape on the reflector of the screen, as shown in FIG.
The projection light can be uniformly reflected only within a reflection angle (viewing angle) necessary for viewing an image.

As shown in FIG. 4A, this cross-sectional shape becomes a convex mirror having a period of 2 ° in the equations (1) and (2).
If this is reversed, it becomes a concave mirror. On the other hand, in the expressions (1) and (3), a concave-convex mirror having a period of 4 ° as shown in FIG. As ξ becomes smaller, the reflection sections become denser, and as n becomes larger, the reflection angle in each reflection section is subdivided. Therefore, by setting 映像 as small as possible and n as large as possible, the resolution of an image can be improved. For example, it is desirable to make the width of the reflection section smaller than the width of the projected image of the liquid crystal pixel.

As a method of realizing such a concave-convex structure for adjusting the viewing angle, a die is formed using a cutting machine controlled by a computer, and the screen is reflected by embossing using the die. It may be transcribed to the body. However, it is generally difficult to emboss a reflector structure that satisfies such conditions by using a large-area mold because it is necessary to minimize ξ. Therefore, the projection light 5 cannot be sufficiently uniformly reflected only within a predetermined reflection angle.

On the other hand, according to the configuration of the present invention shown in FIG. 1, the diameter of the polarizing fiber 1 is periodically changed to create a reference for the reflecting surface 14, and furthermore, the distance between the polarizing fibers 1 is increased. Since the concave portion 1b is filled with the resin, the reflection surface 14 of the large-area reflective screen can be formed into a shape close to a predetermined shape. Therefore, the projection light 5 can be uniformly reflected only within the reflection angle required for viewing an image, more easily than embossing.

There is a polarizing screen using a polarizing film. Since such a polarizing film orients a polarization-presenting substance, a mechanical stretching step is usually indispensable, and it is not easy to stretch a wide-area film with a large area in a certain direction. On the other hand, according to the present invention, since a large number of polarizing fibers are arranged instead of the polarizing film, it can be easily stretched in the longitudinal direction of the fiber, and the production of the reflective polarizing screen becomes easy, so that a clear image can be obtained. .

Also, as shown in FIG. 6, the first polarization direction D1
When the polarizing fiber 1 is knitted by the non-polarizing fiber 15 extending to the second direction D2, the polarizing fiber 1 is also gently and periodically curved in the first direction D1. Also, the projection light can be relatively uniformly reflected only within a predetermined reflection angle.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 5 to 9 show a first embodiment of the present invention, and FIG. 5 shows a polarizing fiber 1 forming a polarizing woven fabric (polarizing member) of the present invention. The polarizing fiber 1 is obtained by adding a polarization-expressing substance made of iodine or a dichroic organic dye to a fiber made of a material such as polyvinyl alcohol or ethylene vinyl alcohol, which has an affinity for the substance. Is stretched in the longitudinal direction L, and the iodine cluster and the dichroic organic dye C are oriented in the fiber stretching direction L in the stretched material, thereby exhibiting a polarizing function. As a result, the polarizing fiber 1 transmits light having a first polarization direction (electric field vibration plane) D1 orthogonal to the longitudinal direction L, and changes the second polarization direction (electric field vibration plane) D2 parallel to the longitudinal direction L. Absorbs light.

An example of a method for producing the polarizing fiber 1 is as follows. First, polyvinyl alcohol (PVA)
And then immersed in a mixed aqueous solution of iodine and an alkali iodide. Then, it is stretched 1.5 to 15 times to obtain the polarizing fiber 1. Alternatively, the polarizing fiber 1 can be obtained by spinning the PVA, stretching it first, and then immersing it in a mixed aqueous solution of iodine and an alkali iodide.

For the polarizing fiber 1, another polymer such as ethylene vinyl alcohol is used in place of polyvinyl alcohol, and a dichroic organic dye such as benzidine is added before or after spinning instead of iodine. It is also possible to manufacture it. Further, for example, a light scattering substance such as titanium oxide may be added to the fiber to constitute the polarizing fiber 1. Due to being a non-aromatic substance, it has a low refractive index and low birefringence, can suppress surface reflection and improve resolution, has high gas barrier properties, and has a reflective screen. When used for a reflective film, the reflective film (for example,
It is preferable to use ethylene vinyl alcohol as the polymer constituting the polarizing fiber 1 because the aluminum film) is not easily oxidized and can be produced by melt spinning and has high operability.

It is preferable to use a dichroic organic dye because it is excellent in moisture resistance and light resistance, has high heat resistance, and can be thermally processed in a later step. The degree of polarization of the dichroic organic dye is generally lower than the degree of polarization of iodine. However, the degree of polarization required for the polarizing screen is 80 to 95%, This can be achieved sufficiently with organic dyes.

The sectional structure of the polarizing fiber 1 is circular, elliptical,
Various shapes such as a shape close to a square can be set, and shapes different from each other may be used. The diameter of the polarizing fiber 1 is determined by the combination of the non-polarizing fiber and the fineness, the flexibility required for winding the screen when not in use, the resolution of the projected image, the moire based on the periodic arrangement of the liquid crystal pixels and the fiber. Although it is restricted by conditions such as prevention, it is generally preferably 10 to several hundreds μm.

FIG. 6 shows a polarizing woven fabric (polarizing member) 2A using the polarizing fiber 1. In the figure, a polarizing fiber 1 is
A large number are arranged in parallel with each other along the second polarization direction D2, and the diameter thereof changes periodically. The polarizing woven fabric 2A is manufactured by weaving the polarizing member 2 with non-polarizing fibers 15 extending in the first polarizing direction D1. Accordingly, the polarization characteristics of the polarization woven fabric 2A are the same as the polarization characteristics of the polarization fiber 1, and transmit light having the first polarization direction D1 and have a second polarization direction D2 orthogonal to the polarization direction. Absorbs light. The non-polarizing fiber 15 may be a transparent fiber or a transparent fiber and an opaque fiber alternately arranged.

The polarizing fiber 1 is composed of seven fibers,
The polarizing fiber bundle 16 is constituted. This polarizing fiber bundle 16
As shown in FIG. 1, a polarizing fiber 1 having the largest diameter is disposed at the center, and the polarizing fiber 1 having a smaller diameter approaches the end.
Is provided, and the outer circumference of the polarizing fiber 1 is, for example, as shown in FIG.
It is arranged so as to be in contact with the curve of (a). For example, by arranging the polarizing fibers 1 having radii of 53.0 μm, 49.4 μm, 40.5 μm, and 29.8 μm, the period T1 in FIG.
A polarizing fiber bundle 16 of 0 μm can be produced. Note that the center of each polarizing fiber 1 in FIG. 1 is arranged on a straight line.

As shown in FIG. 7A, the polarizing woven fabric 2
A has a five-sheet satin weave structure in which a polarizing fiber bundle 16 is woven by the non-polarizing fiber 15. As shown in the cross-sectional view of FIG. 8A, the non-polarizing fiber 15 includes the polarizing fiber bundle 16 as one unit, and the polarizing fiber 1 is woven.

On the opposite surface 1a of the polarizing fiber 1 shown in FIG. 6 where the projection light 5 is incident, for example, a solution in which an acrylic resin is dissolved (for example, a 1-4 dioxane solution)
Then, the polarizing woven fabric 2A is immersed and dried, so that the concave portions 1b between the polarizing fibers 1 are filled with resin. The concave portion 1b is filled with resin in order to make the reflective surface 14 a smooth curved surface and to keep the shape of the polarizing woven fabric 2A in advance. Therefore, the resin is not limited to the acrylic resin described above, and may be any transparent resin having a small difference in refractive index between the polarizing fiber 1 and the non-polarizing fiber 15. The incident surface 13b of the projection light 5 in the resin layer 13, that is, the minute gap formed between the polarizing fiber 1 and the non-polarizing fiber 15, is rough due to the viscosity of the resin.

A reflective surface 14 is formed on the surface 13a of the resin layer 13 by depositing a metal such as aluminum having a thickness of, for example, about 1,000 mm. This reflection surface 14
An adhesive layer 18 is interposed between the support 17 and the support 17 that holds the polarizing woven fabric 2A. As the support 17, for example, a soft PVC (polyvinyl chloride) sheet having a thickness of about 400 μm can be used. 8A and 8B, the gap S between the reflecting surface 14 and the support 17 is slightly different depending on the location, so that the shape of the reflecting surface 14 can be maintained. In consideration of this gap S
It is preferable to use a material that can easily fill the space.

As shown in FIG. 7B, the polarizing fiber 1 is
Since it is woven by the non-polarizing fiber 15, the surface of the polarizing fiber 1 opposite to the projection light 5 (reflection surface 14) is also gently curved in the second polarization direction D2 (vertical direction).

FIG. 9 shows an example of how the reflective polarizing screen 20 is used. In FIG. 9, a projector 4 composed of an LCD is installed in front of a reflective polarizing screen 20, and an image is projected on the reflective polarizing screen 20 by a projection light 5 from the projector 4, so that a viewer 6 can see the screen. 20
Watch the video from the front of the. Outside light 9 and 10 enter the room 11 through the illumination light source 7 and the window 8. The projector 4 is LC
D, the projection light 5 has a specific polarization direction, while the polarization woven fabric 2A has the first transmission direction, which is the transmission direction.
Are arranged so that the polarization direction D1 of the projection light 5 matches the specific polarization direction of the projection light 5.

By arranging the reflective polarizing screen 20 in this manner, most of the projection light 5 can be reflected by the reflective polarizing screen 2.
Since it is reflected by 0, the brightness of the image is kept high. On the other hand, external light 9, 10 from the illumination light source 7 and the window 8
Of the components, those other than the component having the first polarization direction D1 in FIG. 6 are absorbed by the polarizing woven fabric 2A of the reflective polarizing screen 20. Therefore, the contrast of the image is not reduced by the external light 9, 10 (FIG. 9), and the image becomes clear.

Here, the reflection type polarizing screen 20
For example, by making the polarizing fiber 1 thicker in the center and thinner as it approaches the end, and periodically changing its diameter, a reference for the reflecting surface 14 is created. Since the recess 1b is filled with the resin layer 13,
The reflective surface 14 of the large-area reflective polarizing screen 20 can be formed into a shape close to, for example, the shape shown in FIG. Therefore, the projection light can be evenly reflected only within the reflection angle required for viewing the image more easily than by embossing.

In this embodiment, the non-polarizing fiber 15 shown in FIG.
Since the light is also gently curved in the polarization direction D2, the viewing angle in the second polarization direction D2 is also increased.

The reflection type polarizing screen 20 is
Since the polarizing fiber 1 is used instead of the polarizing film, the polarizing fiber 1 can be easily stretched in the longitudinal direction L, so that a large-sized flat film can be easily manufactured as compared with a conventional film. Also, since it is more flexible than conventional films, it can be easily adapted to a curved surface shape, and can be easily wound up, so that it can be wound up and stored compactly when not in use.

FIG. 10 shows a second embodiment. FIG. 10 (a)
6, the polarizing member does not have the non-polarizing fiber 15 of the first embodiment of FIG. 6, and the polarizing fiber array 2B in which the polarizing fiber bundle 16 of FIG. 10A is arranged in the second polarizing direction D2.
It is constituted by. Although the shape of the reflecting surface 14 is slightly different from the shape of the reflecting surface 14 in FIG. 6, the same effect as in the first embodiment can be obtained in the second embodiment in FIG.

FIG. 10B shows a method of manufacturing the reflective polarizing screen 20 of the second embodiment. As shown in this figure, both ends of a large number of polarizing fiber bundles 16 are connected to a pair of elastic members 30 and 3.
The polarizing fibers 1 are arranged in a straight line, sandwiched by 0. In this state, the resin layer 13 is applied to the concave portion 1b on one side of the polarizing fiber 1 to fill the concave portion 1b, and further, the reflection surface 14 shown in FIG.
Is formed by vapor deposition, and the reflection surface 14 and the support 17 are bonded to each other. After this bonding, the end of the polarizing fiber 1 is cut and removed.

In each of the above embodiments, the shape of the reflecting surface 14 is shaped like a curve shown in FIG. 4A. However, in the present invention, the shape of the reflecting surface 14 is shaped like a curve shown in FIG. The shape may be used, or another shape may be set. Also, as shown in FIG. 1, each polarizing fiber 1 is not necessarily
It is not necessary that the centers be aligned on a straight line.
4 may have a predetermined gentle curved shape.

[Brief description of the drawings]

FIG. 1 is a plan sectional view showing an example of a basic module of a polarizing member of the present invention.

FIG. 2 is a conceptual diagram showing a reflection section formed by dividing a projection light approximated by a plane wave and a half angle of view into n equal parts.

FIG. 3 is a characteristic diagram showing an example of an ideal luminance distribution in a horizontal direction or a vertical direction of a screen.

FIG. 4A is a graph showing a cross-sectional shape of a reflecting surface when Expressions (1), (2), and (4) are used;
(B) is a graph showing the cross-sectional shape of the reflecting surface when using equations (1), (3) and (4).

FIG. 5 is a perspective view showing an example of a polarizing fiber.

FIG. 6 is a perspective view showing a part of the reflective screen according to the first embodiment of the present invention.

7A is a front view of the same, and FIG. 7B is a vertical sectional view of the same.

FIG. 8A is a sectional view taken along line 8a-8a in FIG. 7A;
(B) is a sectional view along line 8b-8b.

FIG. 9 is a schematic side view showing an example of a projection facility.

FIG. 10A is a perspective view showing a part of a reflective screen according to a second embodiment, and FIG. 10B is a perspective view showing the manufacturing method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Polarized fiber, 1a ... Surface, 1b ... Depression, 2 ... Polarized member, 2A ... Polarized woven fabric, 2B ... Polarized fiber array, 13 ... Resin layer, 13a ... Surface, 14 ... Reflective surface, 15 ... Non-polarized fiber, D1: first polarization direction; D2: second polarization direction.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eige Noguchi 1621 Sazu, Kurashiki City, Okayama Prefecture Kuraray Co., Ltd. (56) References JP-A-2-163731 (JP, A) JP-A-2-8829 (JP) , A) Hikaru 1-166335 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 5/74 G03B 21/60

Claims (2)

(57) [Claims] 1. Transmitting light having a first polarization direction,
In a reflective screen provided with a polarizing member that absorbs light having a second polarization direction orthogonal to this, a plurality of polarizing fibers are arranged in parallel with each other along the second polarization direction, and A polarizing member is formed by periodically changing the diameter, a transparent resin layer is provided on the surface of the polarizing fiber to fill the recesses between the polarizing fibers, and a reflective surface is formed on the surface of the resin layer. Reflective screen. 2. The reflection screen according to claim 1, wherein the polarizing member is woven with the polarizing fibers by non-polarizing fibers extending in the first polarization direction.