JP2002236319A - Transmission type screen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission type screen with relatively low cost which is bright, whose resolution is high, which has the wide angle of visibility in both horizontal and vertical directions, which is excellent in contrast and on which a distinct picture is observed as a screen for a projection type rear projection television. SOLUTION: A light diffusing plate constituted to have light diffusing layers where the dispersion density of light diffusing material is varied for each of two or more layers in a thickness direction is adopted as the light diffusing base plate having the light diffusing layer constituted by dispersing and mixing the light diffusing material in resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission screen used for a projection type projection television or the like.

[0002]

2. Description of the Related Art As one of conventional transmission screens,
2. Description of the Related Art A transmissive screen generally used for a projection type projection television having a CRT projector is known (see FIG. 2). The screen is usually
It may be composed of at least two lens sheet members, a double-sided lenticular lens sheet 20 and a Fresnel lens sheet 10, in order from the observer side, and a flat protective plate 30 may be arranged at the outermost position on the observer side.

The double-sided lenticular lens sheet 20 is a lenticular lens sheet having a structure in which lens portions 22 and 23 in which a plurality of vertically long cylindrical lenses having a vertical direction as a longitudinal direction are continuously arranged in a horizontal direction are formed on both sides. The projection side lens unit 22 has a function of refracting and diffusing image light projected from the projector in the horizontal direction, and the other observation side lens unit 23 has a color shift (a color shift) due to a synergistic action with the projection side lens unit. (A problem of color shift of emitted light) caused by a three-tube projector arranged off-axis.

On the other hand, the image light needs to be widened not only in the horizontal direction but also in the vertical direction so that the observer can see it. In the vertical direction, the light is not diffused and diffused by the lens but diffused by the light diffusing material. The viewing zone is widened, and a method of applying the light diffusing material 24 to the lenticular lens sheet is adopted.

In applying the light diffusing material, the light diffusing material is mixed into the lenticular lens sheet itself to disperse the light diffusing material inside the lens sheet, or the light diffusing material is formed as a separate member from the lens sheet. A method of applying an ink containing ink to a lenticular lens sheet or laminating a resin sheet formed by kneading a light diffusing material and extruding the lenticular lens sheet is appropriately adopted.

Further, a convex portion is provided at the boundary of the cylindrical lens on the observation surface side of the double-sided lenticular lens sheet, and a light shielding layer 25 is formed on a flat portion at the apex thereof by printing with black ink or the like, or by transfer forming. The configuration is common. The main purpose of forming the light-shielding layer 25 is to improve the contrast of a viewed image, absorb external light, and prevent an observer from seeing the reflection on the screen surface.

In the double-sided lenticular lens sheet 20,
Since the exposed observation surface has irregularities, dust and dirt are likely to adhere thereto, and a protective plate 30 may be provided to prevent the dust and dirt from adhering and to protect the light shielding layer. Normal,
The surface of the protective plate 31 is generally provided with a surface treatment layer 38 such as a scratch-resistant hard coat or an antistatic treatment.

In recent years, a liquid crystal projector having features such as low power consumption, light weight and thinness has been provided with respect to a projection type projection television having a CRT projector (hereinafter referred to as a CRT projection type rear projection television). Projection type projection television (hereinafter, referred to as liquid crystal projection type rear projection television)
Has become popular.

[0009] In particular, with the advancement of video sources for digital high definition, etc., the development of televisions using a high definition liquid crystal panel has been actively pursued, and bright and high resolution liquid crystal projection type rear projection televisions have also been developed. There is a need for a transmissive screen that has a wide viewing angle in both horizontal and vertical directions with a high resolution, excellent contrast, and a clear image.

[0010] In the case of a CRT projection type rear projection television, as described above, projection is performed by three RGB tubes, and in order to correct a color shift caused by a positional difference between the three tubes, a transmission type screen is provided. Whereas a double-sided lenticular lens sheet is used, in the case of a liquid crystal projection type rear projection television, the image light specified by the liquid crystal panel is projected through a monocular lens, and no color shift due to the position difference occurs, so the transmission type A single-sided lenticular lens sheet having a lens portion on only one side can be used for the screen.

FIG. 3 shows an example of a transmission type screen used in a liquid crystal projection type rear projection television. The screen has at least a lenticular sheet 70,
The Fresnel lens sheet 60 is composed of two members.

The lenticular sheet 70 generally has a single-sided lens portion (single-sided) in which a plurality of vertically long cylindrical lenses having a longitudinal direction perpendicular to the screen surface are continuously arranged in the horizontal direction of the screen surface. Lenticular sheet), which has the function of refracting and diffusing image light in the horizontal direction.

A light-shielding layer 75 is formed on the flat surface on the side opposite to the lens portion, which is the observation surface side, as in the case of the double-sided lenticular lens sheet, to prevent reflection by external light and to improve the contrast of a visual image.

Further, as in the case of a CRT projection type rear projection television, it is necessary to widen the viewing area by the diffusion action of the light diffusing material, and a method of applying the light diffusing material to the lenticular sheet is adopted. The applicant has
A lenticular sheet having a configuration in which a light diffusion layer is formed on a light-shielding layer of a single-sided lenticular sheet has been proposed. (JP-A-9-120101)

As the light diffusion layer 80, a resin sheet (diffusion plate) 84 formed by applying an ink containing a light diffusion material on the light shielding layer of a lenticular sheet or kneading the light diffusion material and extruding the lenticular sheet is used. A method such as lamination is appropriately adopted. In the latter case, when a separately manufactured diffusion plate 81 is bonded to the lenticular sheet 70 via the adhesive layer 87, the lenticular sheet 70 also has an effect of imparting rigidity. In the figure, the diffusion plate
This is a description of the light diffusion layer 80 in which a surface treatment layer 88 for performing a desired surface treatment (hard coat, antistatic, antireflection) is formed on the surface 81 as needed.

In the diffusion plate 81 in which the light diffusion material is dispersed and mixed, the light diffusion material 84 is exposed from the surface, and the surface smoothness of the diffusion plate is low. Therefore, when the diffusion plate 80 is laminated on the lenticular sheet 70, there is a problem in handling such that the adhesiveness is not good and the selection of the adhesive 87 is restricted.

As an application related to the light diffusion layer for a screen, Japanese Patent Application Laid-Open No. 11-271510 by the present applicant is known. The application is "a light diffusing plate, wherein the outer layer on the front and back sides is a light-transmitting resin, and the intermediate layer has a three-layer structure in which the light-transmitting resin in which diffusing fine particles are dispersed".

The problem to be solved in the above-mentioned application is that when an optically transparent resin (intermediate layer) in which diffusible fine particles are dispersed via an adhesive is laminated on another screen member (such as a lenticular sheet), the influence of the adhesive is If the light diffusion characteristics change from the initial characteristics, or if the surface state where the diffusible particles protrude from the intermediate layer is formed, there is a problem in the adhesion between the light diffusion plate and other screen members. Since there is concern about environmental changes and durability such as temperature and humidity, the intermediate layer is protected by light-transmitting resin on the front and back outer layers,
The purpose is to maintain the smoothness of the surface.

By the way, there is a demand for a light diffusion layer suitable for a screen in order to cope with a problem peculiar to a liquid crystal projection type rear projection television.

Since the diameter of the projection pupil of the projection lens of the liquid crystal projector is small, the following phenomena are remarkable as compared with the CRT projector. The "hot bar" phenomenon in which the luminance of the center point of the incident light from the projector is locally increased (hot spot), and the stripes appear bright in the direction in which the cylindrical lenses are arranged. The phenomenon of "scintillation", which is unnecessary flickering visible in a projected image.

In order to avoid the hot bar, it is necessary to increase the light diffusivity, and it is necessary to increase the light diffusivity in the direction (vertical direction) perpendicular to the direction in which the cylindrical lenses are arranged. Therefore, a proposal for increasing the thickness of the light diffusion layer has been made in Japanese Patent Application Laid-Open No. 10-83029 by the present applicant.

On the other hand, in order to achieve high definition of the image quality, it is desirable that the light diffusion layer is as thin as possible so as not to cause a decrease in resolution, and this is a configuration which is contrary to avoiding a hot bar.

[0023]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been developed as a screen for a projection-type rear projection television (in particular, using a high-definition liquid crystal panel) with high brightness and high resolution. It is an object of the present invention to provide a transmission type screen having a wide viewing angle in both horizontal and vertical directions, excellent contrast, and capable of observing a clear image at a relatively low cost.

[0024]

According to the present invention, in a light diffusion substrate having a light diffusion layer in which a light diffusion material is dispersed and mixed in a resin, the concentration at which the light diffusion material is dispersed is 2 in the thickness direction. A light-diffusing substrate characterized by having a different light-diffusing layer in layers or more is employed.

If the light diffusing substrate is formed by laminating two or more resin layers (light diffusing layers) containing a light diffusing material on one surface of a transparent resin substrate not containing a light diffusing material, When laminated on a sheet, it is preferable in terms of handling, and by increasing the thickness of the transparent resin substrate,
Sufficient rigidity can be provided without causing a significant increase in cost.

The light diffusion layer may be constituted by a resin sheet formed by kneading and extruding a light diffusion material, or by applying and forming an ink containing the light diffusion material. The ink may be one that also serves as a surface treatment such as a hard coat treatment, an antistatic treatment, and an antireflection treatment.

The transmissive screen to which the above-mentioned light diffusing substrate is applied includes a Fresnel lens sheet having a function of emitting projection light from a projector as substantially parallel light to a lenticular sheet disposed on the viewer side, and a Fresnel lens sheet. A lenticular sheet having at least a function of receiving the light emitted from the lens and diverging the substantially parallel light in the horizontal direction and emitting the light by the function of the cylindrical lens group arranged in the horizontal direction. At least one of the lenticular sheet and the lenticular sheet has irregularities forming the lens portion formed on the surface of the substrate (light diffusion substrate) in which the light diffusion material is dispersed, and at least one of the light diffusion substrates has the dispersion of the light diffusion material. The concentration is different in two or more layers in the thickness direction of the substrate.

A more preferable configuration of the transmission screen is as follows.
A Fresnel lens sheet that has a function of emitting light projected from the projector as substantially parallel light to a lenticular sheet disposed on the viewer side, and a cylindrical lens that receives light emitted from the Fresnel lens sheet and is arranged in a horizontal direction.
In a transmissive screen having at least a lenticular sheet having a function of spreading and emitting substantially parallel light in the horizontal direction by the function of the lens group, the Fresnel lens sheet is a substrate (light diffusion substrate) in which a light diffusion material is dispersed. )
On one side, irregularities constituting a lens portion (preferably made of a cured product of a radiation-curable resin) are formed, and on the other side, the functions of a cylindrical lens group arranged in a vertical direction enable The projections and depressions of the lens portion having the function of expanding and emitting the projection light in the vertical direction are formed, and the lenticular sheet has a cylindrical lens group arranged in a horizontal direction on one surface of the substrate on the Fresnel lens sheet side, It is formed of a resin molded product (preferably, a cured product of a radiation-curable resin). On the other surface, a stripe-shaped light-shielding layer is formed at a position corresponding to the boundary of the cylindrical lens, and contains a light diffusing material. A light diffusion substrate having a structure in which two or more resin layers (light diffusion layers) containing a light diffusion material are laminated on one surface of a transparent resin substrate, Are stacked so as the side that does not include wood facing, the light diffusion layer, the concentration is dispersion of light diffusing material, characterized in that it is a different configuration for over two layers in the thickness direction of the substrate.

<Operation> Since the light diffusion layer has a multilayer structure, the light diffusion substrate can be used as a whole or as a lens sheet (Fresnel,
This is suitable for desirably controlling the light diffusion characteristics according to the lens characteristics of the lenticular lens.

If the light diffusion layer is composed of only one layer in which the concentration of the light diffusion material is uniform, the mixing amount of the light diffusion material is increased in order to provide a practically sufficient light diffusion property. In addition to the appearance of rough feeling with uneven surface, the external light reflectance is high, but the light diffusion layer with low density is arranged on the observer side, so that the matte feeling and the external light reflectance are appropriate. With the appearance.

[0031]

Embodiments of the present invention will be described below. (See FIG. 1) In the following description, a lenticular (lens part) having an action of refracting incident light in the horizontal direction is referred to as a “horizontal lenticular”, and a lenticular (lens part) having an action of refracting light in the vertical direction is referred to as “vertical lenticular”. ".

The Fresnel lens sheet 90 includes a light diffusing substrate 91
On one side (non-projector side), a lens portion 92 made of a resin such as a cured product of a radiation-curable resin is formed.
On the other surface (on the projector side), a vertical lenticular 93 is formed.

As a resin base material constituting the light diffusion substrate 91, polyester resin, styrene resin, acrylic resin,
Acrylic-styrene copolymer resin, polycarbonate resin, vinyl chloride resin sheet and the like can be mentioned, but not particularly limited.

The resin base material has a particle size of 1 to 30.
A light diffusing material 94 mainly composed of spherical glass beads or resin cross-linked beads of μm is dispersed and mixed.

The horizontal lenticular sheet 100 is
1 The cylindrical lens group on the Fresnel lens sheet side
102 is formed of a resin such as a cured product of a radiation-curable resin.On the other surface, a stripe-shaped light-shielding layer 105 is formed at a position corresponding to the boundary of the cylindrical lens, and a light diffusion layer is formed thereon. (Light diffusing substrate) 200 is laminated.

As described above, the substrate 101 may be a polyester resin, a polystyrene resin, an acrylic resin, an acryl-styrene copolymer resin, a polycarbonate resin, a vinyl chloride resin sheet, or the like, but the material is not limited to these. Absent.

The light diffusion substrate 200 has a structure in which two or more resin layers (light diffusion layers) 208 containing a light diffusion material are laminated on one surface of a transparent resin substrate 201 containing no light diffusion material.
It is laminated via the adhesive layer 207 such that the side not including the light diffusing material faces the light shielding layer 105 side.

An acrylic resin or an acrylic-styrene copolymer resin (M
A resin plate having rigidity and excellent light transmittance, such as S resin) and polycarbonate resin, can be used, but is not particularly limited.

The light diffusing layer 208 has a structure in which the concentration of the light diffusing material dispersed in two or more layers in the thickness direction of the substrate is shown in an enlarged manner in FIG. In the present embodiment, the first light diffusion layer / the second light diffusion layer is formed in this order on the transparent resin substrate 201, but the second light diffusion layer also serves as a hard coat layer which is one of the surface treatments. In addition, the prescription for forming the second light diffusion layer contains a filler that imparts abrasion resistance in addition to the light diffusion material.

The first light diffusion layer is made of an acrylic resin in which an inorganic diffusion material such as silica is dispersed at a concentration of 30%.
It is formed by coating at about μm. Second
The light diffusion layer is made of organic cross-linked beads such as acrylic or MS.
It is formed by coating an acrylic resin dispersed at a concentration of 5% with a film thickness of about 20 μm.

The second light diffusion layer is not limited to the above (hard coat treatment), but may also have various functions such as antistatic treatment and antireflection treatment.

The first light diffusion layer / second light diffusion layer has
UV-curable coatings may be used. Ultraviolet-curable paints are generally composed mainly of polymers, oligomers, monomers, etc. having a radically polymerizable double bond or an epoxy group in the structure as a film-forming component, and other photopolymerization. Contains initiator and sensitizer. Preferably, the film forming component uses a polyfunctional (meth) acrylate-based UV-curable paint having an acrylate-based functional group, and particularly the surface hardness, transparency, abrasion resistance, and scratch resistance of the second layer. For example, a hard coat layer having excellent properties can be formed simultaneously with the diffusion layer.

The method of applying the ultraviolet-curable paint to the resin plate is preferably gravure coating, gravure reverse coating, reverse roll coating, offset gravure coating, etc., which are particularly excellent in accuracy of coating thickness and smoothness of the coating surface. is there. Further, it can be formed by transfer using a transfer sheet having a hard coat layer as a transfer layer.

The second light diffusion layer made of an ultraviolet-curable paint is
When performing light diffusion, hard coating and antistatic at the same time,
Generally, a fine powder such as a surfactant is added as an antistatic agent to the ultraviolet curable acrylic resin. The type and amount of the antistatic agent are not particularly limited.

As the antireflection layer, a thin film made of a material having a low refractive index, a transparent fluorine-based resin or a fluorine-based inorganic compound is formed on the light diffusion substrate on the surface of the second light diffusion layer by coating or vapor deposition. However, the material and the forming method of the low refractive index are not particularly limited, whereby the external light contrast is improved, and an image without reflection is visually recognized.

The light diffusion substrate generally needs a thickness of about 0.5 to 2 mm from the viewpoint of light diffusion characteristics and rigidity. In the case of the above embodiment, the light diffusion substrate 91 in the Fresnel lens sheet 90 is entirely formed of a resin layer containing a light diffusion material (light diffusion layer).
However, the light-diffusing substrate 200 is mostly occupied by the transparent resin substrate 201, and the light-diffusing layer 208 is only a part (about 20 to 100 μm) in the thickness ratio.

In the light diffusion layer, there are various restrictions on the difference in the refractive index between the light diffusion material (fine particles) and the resin in which the light diffusion material is dispersed and mixed, a suitable combination for uniformly dispersing and mixing the whole, and a molding method. A sheet-shaped light-diffusing substrate having a thickness (about 0.5 to 2 mm) having a sufficient rigidity and made entirely of a light-diffusing layer has a high cost ratio in the entire screen.

According to the configuration according to the above embodiment, the light diffusion substrate composed entirely of the light diffusion layer is only the Fresnel lens sheet 90 side, and the substrate on the horizontal lenticular sheet 100 side has a low cost configuration. Since the diffusion layer is relatively thin, high definition of the image quality can be achieved without lowering the display brightness and resolution.

The light diffusion layer on the side of the horizontal lenticular sheet 100 has a multilayer structure, and the light diffusion characteristics can be easily controlled by the combination thereof. Can be controlled, including a combination of the pitch of the vertical lenticular 93 in the Fresnel lens sheet 90 and the lens characteristics (emission angle range).

Also, the synergistic action of the vertical refraction and diffusion of the image light according to the vertical lenticular 93 in the Fresnel lens sheet 90 and the horizontal refraction and diffusion of the horizontal lenticular sheet 100 reduces the amount of light on the screen screen. A screen with uniform control and uniform brightness can be obtained.

Light diffusion substrate 91 in Fresnel lens sheet 90
The light diffusing material (fine particles) 94 is mainly composed of a spherical shape having a particle diameter of 10 to 100 μm and containing an organic diffusing material as a component.

As the light diffusing material on the Fresnel lens sheet side, the above-mentioned materials are preferable because inorganic diffusing materials generally have an irregular shape and cause random light diffusion. After the light projected from the lens is randomly diffused and then incident on the Fresnel lens unit, the characteristics of the Fresnel lens are impaired. This is because the light diffusing material containing an organic diffusing material as a component is easy to obtain a spherical and uniform shape, and is suitable for emitting light to the horizontal lenticular sheet side without impairing the characteristics of the Fresnel lens.

The transmitted light (La) obtained by transmitting the light projected from the projector through the diffusion layer of the Fresnel lens sheet can be represented by the sum of the parallel light (L1) and the diffused light (L2). The transmitted light (La) is refracted in the optical path by the Fresnel lens portion and enters the lens surface of the horizontal lenticular sheet.
The light is emitted to the observation side.

The transmitted light that has passed through the Fresnel lens sheet enters the lens surface of the horizontal lenticular sheet, and passes through the screen opening corresponding to the condensing portion of the lens other than the light-shielding layer 105. In contrast, since the parallel light (L1) component is small, even when the ratio (BS ratio) occupied by the light-shielding layer (BS = black stripe) is 50% or more, the kick by the BS is small, and the utilization efficiency of the projection light from the projector is reduced. And a bright display image can be visually recognized. The BS ratio (%) is represented by 100 × light shielding part / (opening part + light shielding part).

FIG. 4 is an explanatory view showing a structure of a screen using a substrate 200 having only a transparent resin substrate 201 and having no light diffusion layer, which is a structure in comparison with the present invention shown in FIG. However, when there is no light diffusion layer on the viewer side than the light-shielding layer 105, the horizontal viewing angle tends to be narrower as the angle of view increases. This is because when the light passing through the opening (the portion of the non-BS portion through which light passes) has a diffusion layer on the observation surface and does not have the diffusion layer, the former diffuses the light more than the latter. Therefore, the viewing angle as a whole is widened. (See FIGS. 5 and 6.) FIG. 5 is a graph showing the relationship between the direction in which the screen is viewed (angle of view) and the perceived luminance. When the solid line has a light diffusion layer on the observer side, the dotted line indicates This shows the characteristics when no light diffusion layer is provided on the observer side. FIG. 6 is an explanatory view conceptually showing that when a light diffusion layer is provided on the observer side, the horizontal viewing angle is widened by light diffusion.

[0056]

Embodiments of the present invention will be described below. Examples 1 to 5 in which a light diffusion layer is provided in a two-layer configuration on a transparent resin substrate as a light diffusion substrate located on the viewer side of a lenticular sheet, and Comparative Examples 1 and 2, in which a light diffusion layer is not provided on a transparent resin substrate. Comparative Example 2 in which the light diffusing material is uniformly dispersed and mixed will be described below in comparison.

<Example 1> On one surface of a transparent resin substrate (acrylic having a thickness of 2 mm), a light diffusion layer shown below was applied and formed in this order. The coating thickness is 20 μm for both. First light diffusion layer containing organic diffusion material at a concentration of 30% Second light diffusion layer containing an organic diffusion material at a concentration of 15%

<Example 2> On one surface of a transparent resin substrate (acrylic having a thickness of 2 mm), a light diffusion layer shown below was applied and formed in this order. The coating thickness is 20 μm for both. First light diffusion layer containing organic diffusion material at a concentration of 15% Second light diffusion layer containing organic diffusion material at a concentration of 30%

Example 3 A light diffusion layer shown below was applied in this order on one surface of a transparent resin substrate (acrylic having a thickness of 2 mm). The coating thickness is 20 μm for both. First light diffusion layer containing organic diffusion material at 15% concentration Second light diffusion layer containing organic diffusion material at 15% concentration

Example 4 On one surface of a transparent resin substrate (acryl having a thickness of 2 mm), a light diffusion layer shown below was applied and formed in this order. The coating thickness is 20 μm for both. First light diffusion layer containing inorganic diffusion material at a concentration of 30% Second light diffusion layer containing an organic diffusion material at a concentration of 15%

Example 5 On one surface of a transparent resin substrate (acrylic having a thickness of 2 mm), a light diffusion layer shown below was applied and formed in this order. The coating thickness is 20 μm for both. First light diffusion layer containing organic diffusion material at a concentration of 30% Second light diffusion layer containing an inorganic diffusion material at a concentration of 15%

<Comparative Example 1> A transparent resin substrate (acrylic having a thickness of 2 mm) having nothing applied to the surface.

Comparative Example 2 A resin sheet kneaded with an organic light diffusing material and extruded. (2mm thick MS resin)

Various substrates having the structures according to Examples 1 to 5 and Comparative Examples 1 and 2 were used as protective plates 30 in a transmission screen (conventional transmission screen) for a CRT projection type projection television shown in FIG. Were evaluated for screen performance. FIG. 7 is a table showing the screen characteristics of each example and comparative example.

<Consideration> First, when comparing the configuration in which the light diffusion layer is provided on the observer side (Examples 1 to 5) with the configuration in which the light diffusion layer is not provided (Comparative Example 1), in Comparative Example 1, the viewing angle in the horizontal direction is small. ΓH (the angle at which the luminance at the front = 0 ° decreases to 1/10 when moved in the left-right direction) and δH (the same
It can be seen that the angle at the time of decreasing to 1/20) is smaller than in Examples 1 to 5.

This means that the height of the base of the curve (Comparative Example 1) shown by the dotted line in the graph of FIG. 5 is reduced. On the other hand, curves indicated by solid lines (Examples 1 to 5)
5) The base of the base maintains a higher luminance than the dotted line.

The comparison between Examples 1 to 5 and Comparative Example 2 is evaluated by the item of sharpness by visual evaluation of the displayed image.
In Examples 1 to 5, since the light diffusion layer was clearly thin, the blur of the image was small and the sharpness was high.

Next, when comparing Examples 1 to 5,
The observation surface is better when the dispersion concentration of the light diffusing material in the second light diffusion layer is low (Examples 1, 3, 4, and 5) than when the dispersion concentration is high (Example 2). Diffuse reflection (expressed by external light reflectance) is also small. The quality of the appearance of the observation surface is determined by visual evaluation. In order to make the appearance of the observation surface good and to reduce irregular reflection of the surface due to external light, the second outermost surface must be used.
The dispersion concentration of the light diffusion material in the light diffusion layer is preferably about 15%.

In order to widen the viewing angle, it is necessary to increase the dispersion concentration of the light diffusing material.
The degree is preferred. As described above, when the light diffusion characteristic (viewing angle) is prioritized, the appearance is impaired and irregular reflection on the surface is increased. It is preferable that the dispersion concentration of the diffusion material be low on the second light diffusion layer side and high on the first light diffusion layer side. (Examples 1, 4, and 5)

A projection type projection television (CRT,
When observing the light diffusing layer having a certain thickness when viewing the light diffusing layer at a certain angle, the optical path length in the light diffusing layer (in the direction of the line of sight) changes. This causes a problem of subtle color change. this is,
According to the change of the optical path length (in the line of sight) in the light diffusion layer,
It is presumed that the degree of the projected display light passing through the light diffusing material changes.

The above-mentioned color change is represented as a horizontal color change (Δx) and a vertical color change (Δy) in the figure. The smaller these are, the better. Examples 1, 2, 3
Is composed only of an organic diffusing material, and Examples 4 and 5 also include an inorganic diffusing material. It can be seen that the latter has less color change.

This is because inorganic diffusers such as silica and alumina have indefinite shapes, and light diffusion is larger and more random than spherical organic diffusers formed of crosslinked beads such as acrylic and MS. It is supposed to be.

In comparison with Examples 4 and 5, it is remarkable that Example 4 using an inorganic diffusing material having higher light diffusivity in the second light diffusing layer has less color shift.

The above embodiment (comparative example) has been described in connection with the case where the multilayer light diffusion according to the present invention is applied to the transmission screen for a CRT projection type projection television (conventional transmission screen) shown in FIG. However, the present invention is also applicable to a transmissive screen (FIGS. 1 and 3) for a liquid crystal projection type projection television.

In particular, the application of the present invention is preferred in FIG.
It is a screen concerning the structure of. As described above, the adoption of the “light diffusion substrate composed entirely of a light diffusion layer by extrusion molding or the like” used on both the Fresnel lens sheet side and the horizontal lenticular sheet side is changed to only one side (Fresnel lens sheet side), This is because the cost on the horizontal lenticular sheet side can be reduced.

In this case, if the thickness of the light diffusion layer is such that it is applied to one surface of the transparent resin substrate, particularly in the vertical direction,
Since the viewing angle cannot be sufficiently enlarged, the screen according to the configuration of FIG. 1 using the Fresnel lens sheet having the vertical lenticulars formed on the projector side exhibits the best operation and effect according to the present invention.

[0077]

According to the transmission type screen to which the light diffusion layer (light diffusion plate) of the present invention is applied, a screen of a projection type rear projection television (in particular, using a high-definition liquid crystal panel) is bright and has a high resolution. This is effective in providing a screen having a wide viewing angle in both horizontal and vertical directions, excellent contrast, and capable of observing a clear image at a relatively low cost.

(1) The structure of a transmission screen that further enhances the operation and effect of the present invention is a combination of a Fresnel lens sheet having a vertical lenticular lens formed on one side on the projector side and a horizontal lenticular lens sheet. A screen having a configuration in which a relatively thin light diffusion layer formed by coating or the like is formed of a light diffusion plate having a multilayer structure on a transparent resin plate, and a combination of the light diffusion layer and the pitch of the vertical lenticular. , It is easy to control the screen characteristics as desired.

(2) The optical characteristics are improved by the synergistic effect of the light diffusion characteristics of the diffusion layer provided on the (double-sided) Fresnel lens sheet comprising a vertical lenticular lens and a Fresnel lens, and the characteristics of the light diffusion characteristics of the multilayer structure. By controlling the pitch of the vertical lenticular within a range of 0.1 mm or less, a hot bar unique to a liquid crystal projector can be easily eliminated. In addition, it is possible to control color change and to control horizontal and vertical viewing angles.

(3) The vertical lenticular lens provided on one side of the Fresnel lens sheet refracts and diffuses the image light in the vertical direction, and the horizontal lenticular sheet refracts and diffuses the horizontal refraction of the horizontal lenticular sheet. Can be controlled uniformly, and a screen with uniform brightness can be obtained.

(4) A diffusion layer using an amorphous diffusion agent is used as a first light diffusion layer (incident side), and a diffusion layer using a bead-based diffusion material is used as a second light diffusion layer (observation side). In this configuration, the light diffusion material has a dispersion concentration of “second diffusion layer <first diffusion layer”, so that the projection light from the projector passes through the diffusion layer of the double-sided Fresnel lens sheet. Due to the synergistic effect of the diffused light component of light and the light diffusion layer formed on the horizontal lenticular sheet, a wide horizontal viewing angle and a vertical viewing angle can be maintained, and a screen with little loss of transmitted light and high brightness can be obtained.

[0082]

[Brief description of the drawings]

FIGS. 1A and 1B are explanatory views showing an example of the configuration of a transmission screen according to the present invention. FIG. 1A is a perspective view, and FIG.

FIG. 2 is a sectional view showing the configuration of a transmission screen used for a CRT projection type rear projection television.

FIG. 3 is a sectional view showing a configuration of a transmission screen used in a liquid crystal projection type rear projection television.

FIG. 4 is an explanatory view of a transmission screen according to a configuration different from the present invention in contrast to the screen shown in FIG. 1;

FIG. 5 is a graph showing the relationship between the direction in which the screen is viewed (angle of view) and the brightness viewed.

FIG. 6 is an explanatory view conceptually showing that when a light diffusion layer is provided on the observer side, the horizontal viewing angle is widened by light diffusion.

FIG. 7 is a table showing screen characteristics for each example and comparative example.

[Explanation of symbols]

 10, 60, 90: Fresnel lens sheet 20, 70: Lenticular sheet 75, 105: Light shielding layer 80: Light diffusion layer 81: Light diffusion plate 87, 207: Adhesive layer 91, 200 ... Light diffusion substrate 92: Lens part 93 ... Vertical lenticular 94: Light diffusing material 100: Horizontal lenticular sheet 101: Substrate 102: Cylindrical lens group 201: Transparent resin substrate not containing light diffusing material 208: Resin layer containing light diffusing material (light diffusing layer)

Claims (11)

[Claims] 1. A Fresnel lens sheet having a function of emitting projection light from a projector to a lenticular sheet disposed on an observer side as substantially parallel light, and receiving light emitted from the Fresnel lens sheet and being parallel in a horizontal direction. A lenticular sheet having a function of expanding and emitting the substantially parallel light in the horizontal direction by the function of the cylindrical lens group, wherein at least one of the Fresnel lens sheet and the lenticular sheet is a light diffusing material. Substrate (light diffusion substrate)
The surface of the substrate has irregularities forming a lens portion, and at least one of the light diffusion substrates has a structure in which the concentration of the light diffusing material to be dispersed differs in two or more layers in the thickness direction of the substrate. Characteristic transmission screen. 2. A light-diffusing substrate, wherein at least one surface of a resin sheet extruded by kneading a light-diffusing material,
2. The transmission screen according to claim 1, wherein the screen is formed by applying an ink containing a light diffusing material. 3. A light diffusing substrate is formed by laminating another extruded resin sheet having a different concentration into which a light diffusing material is kneaded on the surface of a resin sheet extruded by kneading a light diffusing material. The transmission screen according to claim 1, wherein: 4. A structure in which two or more resin layers containing a light diffusing material (light diffusing layers) are laminated on one surface of a transparent resin substrate not containing a light diffusing material. 4. The transmission screen according to any one of 1 to 3. 5. The transmission screen according to claim 1, wherein the concentration of the light diffusing material dispersed is higher on the projector side than on the observer side. 6. A multi-layer structure wherein the light diffusing material dispersed on the projector side is mainly composed of an inorganic material, and the light diffusing material dispersed on the observer side is mainly composed of an organic material. The transmission screen according to claim 1. 7. A light diffusing material dispersed on the Fresnel lens sheet side is an organic material, and a light diffusing material dispersed on the lenticular sheet side is an inorganic material. The transmission screen according to any one of the above. 8. A structure in which at least one kind of surface treatment selected from a hard coat treatment, an antistatic treatment and an antireflection treatment is applied to the surface of the diffusion substrate on the observer side. 8. The transmission screen according to any one of 1 to 7. 9. An observer-side surface of a resin sheet extruded by kneading a light diffusing material into at least one of a hard coat treatment, an antistatic treatment and an antireflection treatment.
2. The method according to claim 1, wherein the surface treatment also serves to form a light diffusion layer by performing various kinds of surface treatments.
8. The transmission screen according to any one of items 7 to 7. 10. A Fresnel lens sheet having a function of emitting projection light from a projector to a lenticular sheet disposed on the observer side as substantially parallel light, and receiving light emitted from the Fresnel lens sheet and being parallel in a horizontal direction. A lenticular sheet having at least a function of expanding the above-mentioned substantially parallel light in the horizontal direction and emitting the light by the function of the cylindrical lens group described above, wherein the Fresnel lens sheet comprises a substrate ( On one surface of the light diffusing substrate), there are formed irregularities that constitute a lens portion made of a cured product of a radiation-curable resin, and on the other surface, the functions of a cylindrical lens group arranged in a vertical direction allow the projector to emit light from the projector. The projections and depressions that form the lens part that has the function of expanding the projection light in the vertical direction and emitting it are formed. On the one side of the substrate on the Fresnel lens sheet side, a group of cylindrical lenses arranged in a horizontal direction is formed of a cured product of a radiation-curable resin, and the other side corresponds to the boundary of a cylindrical lens. A light-shielding layer in the form of a stripe is formed at a position where light is to be diffused, and two or more resin layers (light diffusion layers) containing a light diffusion material are laminated on one surface of a transparent resin substrate not containing a light diffusion material. A diffusion substrate is laminated on the light-shielding layer side such that the side not including the light diffusion material faces the light diffusion layer, and the light diffusion layer has a dispersed concentration of the light diffusion material of two or more layers in the thickness direction of the substrate. A transmissive screen characterized by different configurations across the screen. 11. A light-diffusing substrate having a light-diffusing layer in which a light-diffusing material is dispersed and mixed in a resin. A light diffusing substrate characterized by having a configuration having: