JPH0273242A - Light transmission type screen - Google Patents

Abstract

PURPOSE:To improve the function of total reflection by providing a surface where projected light is totally reflected, forming a groove by adjacent total reflection surfaces and filling the groove with the mixture of spherical particles whose density is 0.9-1.2g/cm<2> and whose average particle diameter is 1-30mu and light absorbing resin. CONSTITUTION:The total reflection surfaces 7 where the projected light is totally reflected are provided on a lens 8 which constitutes a lenticular lens and the groove 11 is formed by the adjacent surfaces 7. In order to uniformly fill the groove 11, it is desirable to use the spherical particle whose density is 0.9-1.2g/cm<2> and whose average particle diameter is 1-30mu as the spherical particle 5 out of the mixture with which the groove 11 is filled. When the density exceeds 1.2g/cm<2> in a state where the mixture of the particles 5 and the light absorbing resin 6 is mixed with solvent to get paint-like substance, the particles 5 precipitate, so that it is difficult to keep a stable state. When the average particle diameter exceeds 30mu, it is difficult to uniformly wipe out an unnecessary part at the time of wiping it out after applying the mixture of the particles 5 and the resin 6 to the groove 11 and the groove 11 is ununiformly filled.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a light-transmissive screen, and in particular, the present invention relates to a light-transmissive screen that suppresses reflection of external light on the viewing side surface of the screen to improve image contrast, and that has a wide viewing angle. This invention relates to a light-transmissive screen that has been improved to 5.

[Conventional technology]

2. Description of the Related Art Light transmission screens in which each lenticular lens has a total reflection surface have been known in the art in order to widen the viewing angle. (USP No. 3,218,924) Furthermore, in order to prevent a decrease in image contrast due to reflection of external light on the observation side surface of the screen, it has been conventional to form a black external light absorbing part on the light-opaque part of the lenticular lens surface. It is being done.

[Problem to be solved by the invention]

Formation of a light absorbing portion for reducing external light reflection on the screen surface is generally performed by coating with black paint. The total reflection surface included in a lenticular lens unit is a light-opaque area, but if paint is applied directly to this total reflection surface, the light transmitted through the lens will be totally reflected if the difference in refractive index between the lens base material and the paint is small. Instead, it is absorbed by the paint and causes a decrease in the viewing angle of the screen.

There is a method of forming a low refractive index layer between the total reflection surface of the lens and the black paint layer, and causing total reflection at the interface between the lens base material and the low refractive index layer, but this method involves a time-consuming process and is difficult to achieve convergence. It is difficult to mass produce screens at a high rate.

Also, a method is disclosed in which a light-absorbing filament is installed on a groove-shaped total reflection surface, but in order to fix the filament to the groove surface,
An adhesive must be attached around the filament, and since the difference in refractive index between the screen base material and the adhesive is generally small, there is a problem in that total reflection efficiency is reduced.

Also disclosed is a method in which the total reflection surface of the groove wall is filled with light-absorbing particles and the particles are held by an outer skin.

(Unexamined Japanese Patent Publication No. 60-159734) However, it is difficult to uniformly fill the grooves with light-absorbing particles, and the thickness of the stripes formed by the light-absorbing particles may not be constant, or the light-absorbing particles remaining in unnecessary areas may be wiped off. When cleaning the screen, there are problems such as particles being dragged and uneven filling, which impairs the appearance of the screen.Also, if the unnecessary particles are not wiped off sufficiently, it may partially block the light transmitted through the screen. This includes the problem of reducing the brightness of the screen.

[Means to solve the problem]

The present invention was made to solve the above problems. As a result of intensive research, the present inventors found that a mixture of spherical particles with a specific range of density and average particle size and a light-absorbing resin is
The inventors have discovered that lens-transmitted light can be efficiently totally reflected on the total reflection surface of each lenticular lens, and have completed the present invention.

That is, the present invention provides a light transmission type screen in which a lenticular lens extending in the vertical direction is formed in the viewing field f13, and a lens unit 81C constituting the lenticular lens is provided with a total reflection surface 7 that totally reflects the projected light. , a groove 11 is formed by the adjacent total reflection surfaces 7, and the groove 11 has a density of 0.9.
~1.2L et al.3 and an average particle size of 1 to 30μ spherical particles5
The present invention provides a light-transmitting thermal screen characterized in that it is filled with a uniform mixture of a light-absorbing resin 6 and a light-absorbing resin 6. This screen can also be provided with a Fresnel lens on the projection side 2.

FIG. 1 is a perspective view showing an example of use of the screen of the present invention. FIG. 2 is a diagram showing an example of a lenticular lens unit used in the present invention, a groove K formed by a total reflection surface, and a groove K filled with a mixture of spherical particles and a light-absorbing resin.

This lens unit shape was developed by the same applicant in JP-A-63-31.
No. 926.

The present invention is characterized in that the mixture filled in the groove 111C formed by the total reflection surface 7 provided in the lenticular lens unit 8 is characterized. The shape and size of the groove can be set within a common sense range.

This mixture has the ability to totally reflect the light transmitted through the lens, making it possible to design a screen with a wide viewing angle. It also has a light absorption function for external light on the observation side, making it possible to design a screen that provides clearer images. Moreover, the present invention allows the VC to be applied directly to the screen surface on the lenticular side as a paint-like substance mixed with a solvent, and after wiping off unnecessary parts, the solvent is removed by drying. It has the characteristic that the mixture can be filled into the groove.

According to Snell's law, the critical angle θC when a light ray is totally reflected at an interface where media with different refractive indexes meet is θc = a
It is expressed as rcsln(n2A) (where nl>n). Therefore, a light beam traveling through a screen substrate with a refractive index of n will be totally reflected at the interface with a medium with a refractive index of n if the angle of incidence on the interface is larger than the critical angle 0c. It will further advance through the screen base material.

In the present invention, a mixture of spherical particles and a light-absorbing resin is in contact with the total reflection surface of the screen, and the spherical particles are in contact with the total reflection surface with a minimum area such as point contact.

The light-absorbing resin fills the space between the spherical particles, but does not directly contact the total reflection surface of the screen. An air layer 9 is formed in the gap between the light-absorbing resin 6 and the total reflection surface 7, and has at least the minimum thickness necessary for total reflection of light having wavelengths in the visible range. This air layer 9 is formed when the solvent mixed in the coating of the mixture of spherical particles and light-absorbing resin is dried and removed. Figure 3 shows the state of the total reflection surface interface.

As the base material for the screen in the present invention, transparent resins such as acrylic resin, vinyl chloride resin, polycarbonate resin, styrene resin, and polyolefin resin can be used. Among these, acrylic resin is preferred from the viewpoints of transparency, weather resistance, and surface scratch resistance. As a method for molding a lenticular lens, a conventional molding method such as hot pressing, extrusion molding, or injection molding is used.

Further, in order to improve the light diffusing properties of the screen of the present invention, an inorganic or organic light diffusing agent may be added to the transparent resin serving as the base material.

In the present invention, there are no particular restrictions on the covering of the light diffusing agent, etc.
For example, inorganic types include calcium carbonate, barium sulfate, titanium oxide, silicon dioxide, calcium fluoride, talc, glass peas, etc., and organic types include styrene resin, methyl methacrylate/acrylic acid ester/aromatic There are crosslinked polymers mainly composed of vinyl monomers, and any of them can be used alone or in combination of two or more.

Among these, preferred are crosslinked polymers mainly composed of methyl methacrylate/acrylic acid ester/aromatic vinyl monomer with an average particle size of 10 to 100 microns, calcium carbonate, quartz powder, barium sulfate, glass peas, and the like.

In addition, in order to increase the commercial value of the screen, colorants, light stabilizers, heat stabilizers and other additives are added to the screen at a good temperature.

Among the mixture components filled in the grooves formed by the total reflection surface of the lens in the screen of the present invention, the spherical particles have a density of 0.9 to 1.29/cvL'' and an average particle size of 1.
A lifespan of ~30 is preferable for uniform filling. Among them, density 0.90-0.98 g□1, average particle size 2-1
Most preferably, it is 0μ.

If the density exceeds x,21/atl, when the mixture of spherical particles and light-absorbing resin is mixed with a solvent to form a paint-like material, the spherical particles will precipitate, making it difficult to maintain stable properties over time. Although spherical particles with a density of 0.90 g/c♂ are currently difficult to obtain, particles with a density of 0.9 E/cat'' or less may also be used as long as the object of the present invention can be achieved.

Furthermore, if the average particle size exceeds 30μ, when applying a mixture of spherical particles and light-absorbing resin to the grooves and wiping off unnecessary parts,
It is difficult to wipe it off evenly, and the grooves are filled unevenly. Moreover, since it is currently difficult to obtain particles with an average particle diameter of less than 1 μm, 1 p was set as the lower limit.

Here, the average particle size refers to the particle size corresponding to 50% of the cumulative volume on an integral curve in which the horizontal axis is the particle size and the vertical axis is the cumulative total of particle volumes up to K - constant particle size. It can be determined using a device such as a Coulter Counter (Coulter Electronics, Inc., USA).

In the present invention, it is necessary that the shape of the spherical particles is not irregular in order to uniformly fill the grooves. A shape ranging from a circular shape to a true sphere is preferable, and a true sphere or a shape close to this is most preferable.

There are no particular restrictions on the material for the spherical particles, but organic polymers are generally preferred. Examples include homopolymers or copolymers of vinyl monomers such as ethylene, styrene, and methyl methacrylate. Among these, polyethylene is most preferable in terms of density.

In the screen of the present invention, the five light-absorbing resins in the mixture filled in the groove formed by the total reflection surface of the lens are general-purpose resins such as silicone resin, polyester resin, epoxy resin, alkyd resin, acrylic resin, and fluororesin. Resins can be used alone or in mixtures. Furthermore, in order to impart light absorption properties, carbon black or coloring pigments or dyes can be uniformly dispersed in the resin. In addition, auxiliary materials such as a solvent and an antifoaming agent can be used for uniform dispersion.

When mixing spherical particles and light-absorbing resin, if the proportion of spherical particles is large, the total reflection performance is good, but the grooves are likely to be filled unevenly during squeegee wiping, and the light-absorbing performance is also degraded. Conversely, if the proportion of spherical particles is small, the total reflection performance will decrease.

The mixing ratio of the spherical particles and the light-absorbing resin should be in the range of 3/1 to 1/3 by weight in order to maintain total reflection performance, fill the grooves uniformly, and have light-absorbing performance. is preferred. It is preferable that the mixture be sufficiently mixed using an ordinary stirrer or roll so that the spherical particles are uniformly dispersed.

The method of filling the grooves on the surface of the lenticular lens with a mixture of spherical particles and a light-absorbing resin is to form the mixture into a viscous paint-like substance with an appropriate solvent and then print it directly onto the screen. That is, a solvent is added to a mixture of spherical particles and a light-absorbing resin, and the viscosity is adjusted to an appropriate viscosity, for example, 50 to 5.
After forming a paint-like material with a viscosity of 0.00 voids, preferably 150 to 350 voids, it is applied to the lenticular side surface of the screen, and unnecessary parts of the paint-like material are scraped off with a urethane rubber squeegee used for screen printing. The groove can be more uniformly filled with the paint-like material by removing the material.

Furthermore, the screen is heated at 60 to 80°C for 10 to 60°C.
By heating for a minute, the solvent evaporates and the remaining solids solidify and become fixed in the screen grooves.

Example 1 The present invention will be explained below with reference to Examples, but these are not intended to limit the invention.

(1) The following compounds were charged into a reaction vessel equipped with a light diffusion plate stirrer, a reflux condenser, and a nitrogen gas inlet.

■ Methyl methacrylate 40 parts by weight ■ Butyl acrylate 30 x parts by weight 0 Styrene
30 parts by weight■ Allyl methacrylate 1.5 parts by weight■ t-dodecyl mercaptan
0.3 parts by weight ■ Azobisisobutyronitrile 0.
5 parts by weight ■ Polyvinyl alcohol 360 parts by weight ■ 200 parts by weight Water After the inside of the container was sufficiently replaced with nitrogen gas, the mixture of the above compounds was heated to 70°C with sufficient stirring to proceed with polymerization in nitrogen gas. . After 4 hours, the temperature was raised to 90℃, and then the temperature was increased to 90℃.
The polymerization was completed by holding for a period of time. After the polymerization was completed, granular beads were obtained by dehydration, washing with water, and drying. The obtained beads were sieved to obtain organic crosslinked polymer particles with an average particle size of 48 μm.

Delpera) 70H (manufactured by Asahi Kasei Industries, Ltd.) VC1 5 weight 5 of the obtained light diffusing agent was added, and after heating and mixing in an extruder (resin temperature 250°C), the molten resin coming out of the die was passed between rolls and cooled. A 610x460x3 dragon light diffusing plate was obtained.

(2) Molding of lenticular lenses and Fresnel lenses The substrate manufactured in step (1) was placed between the lenticular lens molds and Fresnel lens molds shown below, and heated with a hot press at a molding temperature of 160°C for a molding time. After molding for 10 minutes at a molding pressure of 30 νd, the molded product was cooled with water for 10 minutes to obtain a molded product.

Lenticular lens unit: Fig. 4 Fresnel lens: Pitch 0.5 mm Focal length 1000 m (3) Formation of external light absorption layer (for Example 1) Full surface K of the lenticular lens for screen molding prepared in (2), True spherical particles 1 made of low-density polyethylene with a density of 0.929/an' and an average particle size of 5.2μ, iron chemical flow beads LE-1080), emulsion silicone resin (active ingredient 45 wt%) and black firing. The mixture was thoroughly stirred and mixed with the pigment at a weight ratio of 2:221, and an appropriate amount of solvent was added to form a paint-like product with a viscosity of 200 voids, which was then applied.

Further, the portion other than the portion corresponding to the external light absorbing layer was scraped off with a urethane rubber squeegee, and heated in a hot air dryer at 80° C. for 30 minutes to form an external light absorbing layer with a uniform line width.

(For Comparative Example 1) Hynylidene fluoride: Tetrafluoroethylene = 80:2
0 was dissolved in methyl isobutyl ketone and applied to the entire surface by a spray method.

The area other than the part corresponding to the external light absorption layer was scraped off with a squeegee and dried in a hot air dryer. Then, Musashi Paint Co., Ltd.'s Plaace 716 AM was applied to the entire surface by spraying.
A portion other than the portion corresponding to the external light absorbing layer was scraped off with a squeegee and dried in a hot air dryer to form an external light absorbing layer.

(Comparative example, February) Apply PLACE 716AM manufactured by Musashi Paint Co., Ltd. to the entire surface by spraying, scrape off the area other than the part corresponding to the external light absorbing layer with a squeegee, and dry in a hot air dryer to form the external light absorbing layer. was formed.

(4) Evaluation A parallel beam of light is incident on a collimator from the Fresnel lens side of the transmission screen made by the above method, and the brightness distribution is measured using a brightness meter (NT-1/3'P manufactured by Minolta). did.

In addition, using a TWTN CABIN 5UPER (cabin industrial lamp: 3QOW lens p3f50B) as a projector, images of the black and white pattern 12 slides shown in Figure 6 were projected onto a prepared transmission screen in a room under fluorescent light illumination. did. Then, the brightness of the white part and the dot part on the screen was measured, and the contrast was calculated from the ratio of the two.

(5) Results The measurement results of the luminance distribution of Example 1 and Comparative Example 1.2 are shown in FIG. From this, it was found that the screen of Example 1 had the highest relative brightness and the largest half-value angle. In other words, it was found that the total reflection surface of the lenticular lens has the best total reflection function.

In addition, the contrast of Example 1 was 80, and that of the comparative example was also 80, and it was found that the contrast was equivalent.

The method for forming the external light absorption layer in Example 1 is simpler than that in Comparative Example 1. That is, in Example 1, a paint-like substance can be applied directly to the surface of the lenticular lens, whereas in Comparative Example 1, a low refractive index layer containing a fluorine-based compound is applied, and after further drying, an external light absorbing paint is applied. The coating process requires time and effort, making it difficult to mass-produce screens with an external light absorption layer at a high yield.

From the above results, it was found that the screen of Example 1 is superior to that of Comparative Example 1 in that the method for forming the external light absorption layer is simple, and it is also superior in brightness distribution performance. Ta.

In addition, the screen of Example 1 has the following characteristics compared to that of Comparative Example 2:
Although the method of forming the external light absorption layer was the same, it was found that the brightness distribution performance was significantly superior.

Examples 2 to 9 Screens were molded using the same light diffusing plates as in Example 1 and the same molds. Furthermore, a mixture of spherical particles and a light-absorbing resin as shown in Table 1 was applied to the entire surface of the lenticular lens, and the portions other than those corresponding to the external light-absorbing layer were scraped off with a squeegee to form an external light-absorbing layer.

Table 1 shows the performance of the screen obtained by the above method.

Good total reflection means that a luminance distribution performance comparable to that of Example 1 can be obtained. In addition, "good printability" means that stripes of the external light absorbing layer with inconspicuous unevenness are formed.

(Effects of the Invention) The light transmission screen of the present invention has an amount of external light absorption that can be formed by a simple method, and the external light absorption layer has a function of efficiently (total reflection) the light transmitted through the lens. Therefore, according to the present invention, it has become possible to produce a screen with good contrast and a wide viewing angle by a simple method.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of use of the screen of the present invention. 5 is a light source, 2 is a screen projection side, 3 is a screen observation side, and 4 is an observer. FIG. 2 is a diagram showing an example of a groove formed by a lenticular lens unit and a total reflection surface used in the present invention, in which a mixture of spherical particles and a light-absorbing resin is filled. 5
is a spherical particle, 6 is a light-absorbing resin, 7 is a total reflection surface, 8 is a lens unit, and 11 is a groove. FIG. 83 is a diagram showing the state of the interface between the total reflection surface of the lenticular lens, the spherical particles, and the light-absorbing resin mixture. 7 is a total reflection surface, 9 is an air layer, and 10 is a lenticular lens portion. FIG. 4 shows an example of a lenticular lens unit. FIG. 5 shows the measurement results of the luminance distribution. FIG. 6 shows a black and white pattern for measuring screen contrast. Patented wheat Asahi Kasei Kogyo Co., Ltd. Figure 2 Figure 4 Figure 5 aNokakueg Figure 3 Figure 6

Claims (2)

[Claims] (1) In a light transmission screen in which a lenticular lens extending in the vertical direction is formed on the viewing side, each lens unit constituting the lenticular lens is provided with a total reflection surface that totally reflects the projected light, and adjacent total reflection surfaces A groove is formed, and the groove has a density of 0.9 to 1.2 g/cm^3,
A light-transmitting screen filled with a uniform mixture of spherical particles with an average particle size of 1 to 30μ and a light-absorbing resin. (2) The light transmission type screen according to claim 1, wherein a Fresnel lens is formed on the projection side.