JPS6115134A - Transmission type screen - Google Patents

Abstract

PURPOSE:To enlarge an angle of a visual field, and also to adjust the angle by forming a lenticular lens extending in the vertical direction on an observation surface, and constituting the total reflecting surface of two or more surfaces whose inclination is different from each other. CONSTITUTION:A transmission type screen is constituted of a projection surface A facing a light source and an observation surface B facing the observation surface side at the side opposite to said surface A, and a lenticular lens extending in the vertical direction is formed on this observation surface B. In a lens unit 1 for constituting this lens, total reflecting surfaces 11, 11 for reflecting totally incident light which has traveled straight to both its dies and has been made incident, and a curved surface part which is at the top part of the lens unit and emits light which has been made incident on said total reflecting surfaces 11, 11 and has been reflected totally are formed. It will do that the top surface is constituted of one curved surface part 12, or constituted of two curved surface parts 12.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a transmissive screen used for example in a video projector, and in particular to a bright transmissive screen whose viewing angle can be largely adjusted. This is related to.

(Prior Art) Transmissive screens are used as projection surfaces for video projectors, microfilm readers, computer displays, etc., but various improvements have been made to their light transmission characteristics, such as increasing the viewing angle. No consideration has been given to this. One of the first means to achieve all of these objectives is to use a lenticular lens in which a large number of minute cylindrical lenses are successively formed, either alone or in combination with other lenses or a diffuser plate. ing.

As mentioned above, this lenticular lens is effective in completely diffusing incident light, and it consists of a large number of tiny cylindrical lenses that are formed in a continuous manner in the vertical direction, and one lens is used to diffuse light and sound in the horizontal direction, increasing the viewing angle. This makes it particularly suitable for this type of screen. By the way, when using this lenticular lens as a screen, the maximum diffusion angle is determined depending on whether the lens surface is facing the incident -f line side, that is, the light source side 1, or when it is facing the exit side, that is, the observer side. It is known that the diffusion angle can be made larger when the light is directed toward the light source than when it is directed toward the viewer.

However, even when a lenticular lens is placed on the observation side, there is a limit to the viewing range if the lenticular lens has a simple circular unit. This is because the collimated light incident from the projection side has a large light loss at large bending angles according to the critical angle condition and Fresnel's equation, so the viewing range is not large. .

In other words, if parallel light (L) is incident as shown in Fig. 19, total reflection occurs when the refractive index of the medium at that time is n + 1nθ = e i n tp = 1. occurs, and the light enters at an angle (θ) of n or more, 'fc, and is not originally transmitted to the observation side. In addition, in Fresnel's equation, the reflectance γ at the interface is expressed as n, and this value becomes large near the critical angle. As shown in Figure 20, the lenticular lens used as a constituent unit has the disadvantage that the amount of light is almost zero when the angle from the center is about 300 degrees, and it cannot be seen in a viewing range that exceeds this angle. ing.

Therefore, as a result of consideration in order to widen the horizontal viewing angle, the present applicant decided to completely reflect a part of the original light incident on the screen from the light source by a part of the vertical lenticular lens and emit it to the viewing side. In particular, he proposed expanding the viewing angle (Japanese Patent Application No. 56-51194, Japanese Patent Application No. 91896-1982, Japanese Patent Application No. 29178-1982, and Japanese Patent Application No. 57-59389). By adopting this unique lenticular structure, we have been able to expand the viewing angle to approximately ±60°.

(Problem to be solved by the invention) By the way, these total reflection surfaces spread out at a large emission angle with a small angle of inclination, but the angle of 0 to ±40 degrees emitted from the top surface Since there would be no overlap with the original, and a gap would be created in the amount of light, there were restrictions on increasing the viewing angle too much. Although the total reflection surface has an excellent function for increasing the viewing angle, it is difficult to create an inclination of the total reflection surface to obtain a well-balanced viewing angle. Therefore, in the present invention, all such total reflection surfaces are divided into two different types.
By configuring the screen in accordance with the above aspects, it is possible to provide a transmission type screen with a good balance by minimizing the amount of light as much as possible.

(Means for solving all problems) The present invention was developed as a result of studying the above problems.
The gist of this is that in a transmission screen that is fully equipped with a projection surface and an observation surface, a lenticular lens extending vertically is formed on the observation surface, and the lens units that make up the lenticular lens are Total reflection surfaces are formed on both sides of the mirror, and each total reflection surface is composed of two or more surfaces with different inclinations. It is a transmissive screen that is characterized by

The present invention will be described below with reference to drawings of embodiments.

The transmission screen of the present invention has a projection surface (A) facing the light source.
The observation surface (B) is the reflective side facing the observer.
A lenticular lens extending in the vertical direction is formed on this viewing surface (B). The lens unit (1) K that makes up the entire lenticular lens has total reflection surfaces (11) and (+1) on both sides of which the incident light that has entered in a straight line is totally reflected, and a total reflection surface (11) and (+1) at the top of the lens unit. A curved surface portion (12) is formed which completely reflects the light incident on the reflecting surfaces (11) and (11) and emits the light 7. In the example shown in Figure 1, the top surface consists of one curved surface part (12), but in the example shown in Figure 2, this curved part (12) consists of two
In the example shown in Fig. 3, the curved surface part (1
A central curved surface portion (13) is formed between 2). In the example shown in FIG. 4, other curved surface portions (2) are formed alternately with the lens units (1) as shown in FIG.

As shown in Figures 2 to 4, if the lens unit (1) in a lenticular lens is composed of two or more curved surfaces (12), it will look like a projection television that uses three tubes and three lenses. , the original distribution can be made uniform even in a projection system having multiple light sources with different angles of incident light. In addition, since the present invention is particularly characterized by the lenticular lens in the observation plane CB),
The projection surface (A) may be flat as shown in Fig. 1, but it is more effective to form the entire Fresnel lens (3) on the projection surface in the construction shown in Figs. 5 to 8. This allows us to provide a complete screen with superior configuration.

The present invention is characterized in that the above-mentioned transmission screen is configured with two or more surfaces having different total inclinations (11). Explain.

First, to explain the original emission of a lens unit having a total reflection surface, as shown in Figure 9, the k incident on the total reflection surface (a)
The light of l is emitted as shown in 1'-11', and the light that is incident on the curved surface portion (b) of l11-■ is emitted as shown as III'-IV'. Furthermore, the source that enters between ■ and ■ is.

Although it is reflected internally and results in a loss, this sir is extremely small and can be ignored. In the figure in dimension I, only one side from the center is omitted for convenience of explanation, but in reality, the remaining side is also symmetrically emitted. In the same figure, II
The light between I-IV spreads from 1 cO to a range of 30 to 40 degrees like a general cylindrical lenticular lens, and the light between I-II
Since the element in between is totally reflected, it will spread in the range of about 20 to 600. Here, if the total reflection surface (4) is a straight line, when the inclination θ is small, the light of I'-〇' will spread to a region with a larger viewing angle, but conversely, the light of m'-
The overlap with the source of rv' is reduced, and a valley appears in the light amount distribution. Conversely, when θ becomes thicker, I'-11'
The source of is emitted to a region with a small viewing angle, and III'-IV
The overlap with the light of If you balance this point and set θ, for example, in the case of acrylic resin, θ will be set at around 70°, and although the material is utilized by total internal reflection, the viewing range will be limited.
That's it. This total reflection surface (A) can be made into a curved surface, but the cutting process of the mold for manufacturing the transmission screen will be complicated, and the precision of reproducibility will be reduced.
It is desirable to construct it as straight as possible.

The present invention was devised in view of this unfortunate situation, and the total reflection surface is formed of two or more surfaces with different sizes. Now, when considering the lens unit (1) as shown in Fig. 10 (A), the light I that enters the lower part (a) of the total reflection surface (11) is emitted as ■' in a small viewing angle range. , '5t incident on the upper part (b) is emitted to a range ■' with a large viewing angle. Therefore, it is ideal for the part (a) to be tilted as large as possible to emit light into a range with a small viewing angle, and for the part (b) to be tilted at a small angle, it is ideal to emit light into a range with a large viewing angle. Figure 10 (B) shows this f″L.
It is.

However, since the part (&) in FIG. 10(B) can be constructed even if the angle of inclination is increased as a whole, it may be constructed with two surfaces as shown in FIG. 11. In other words, a surface with a large angle of inclination (
In the upper part of 11a), a surface with a small angle of inclination (11b
) By forming a total reflection surface (11) in series, a transmissive screen with good balance and a large viewing angle can be obtained.

Forming the entire total reflection surface with a curved surface as described above makes cutting the mold difficult, but it can be greatly improved by combining a curved surface with a linear surface. An example of this is shown in FIG. 12, in which a straight surface (11cl) with a small angle of inclination is entirely connected to the upper part of the curved surface (11c). Therefore, in this case as well, it is possible to obtain a transmissive screen with a well-balanced large viewing angle, but it is also possible to suppress the chipping phenomenon during cutting of the mold, compared to a case where the entire total reflection surface is curved. It has the advantage of being easy to manufacture.

Furthermore, in the transmission screen of the present invention.

It is also possible to increase the contrast by providing an external absorption layer on the viewing surface. Figure 13 shows the lens unit (1) in this case, where (4) is the base layer to prevent the total reflection function from being impaired, and (5) is the base layer provided on this base layer (4). It is an external light absorption layer.

This external light absorbing layer (5) is dark colored such as black to absorb external light, but this direct total reflection surface (11)
When fc is provided, absorption occurs on this surface, resulting in efficient total reflection. Therefore, either a transparent material layer with a low refractive index is provided on the total reflection surface (11) of the screen in advance, or
It is necessary to form a metal reflective layer using metal vapor deposition or metal reflective paint.

Figure 13 (A) t:j This is a case where the base layer (4) and the external light absorbing layer (5) are provided over the entire total reflection surface (11), but CB) is the case where the base layer (4) is provided over the entire total reflection surface (11). This is an example in which the external light absorbing layer (5) is provided only on the surface with a large inclination angle (+ta). Figure (C) of the casing 1 is an example in which the base layer (4) and the external light absorbing layer (5) are all provided only on the surface (11a) with a large inclination angle.

The formation of such a base layer (4) and external light absorbing layer (5) is described in Japanese Patent Application No. 57-46949, which was previously proposed by the present applicant.
It can be formed according to method e of No. The process steps of this method are shown in FIG. 14, in which a removable masking layer (a peelable masking layer) is placed on the top of the lens unit (1) as shown in FIG. 14 (A).
6) Complete the formation, and then form a base layer (4) made of a transparent material with a low refractive index as shown in (B). Further, an external light absorbing layer (5) as shown in (0) is formed on top of B, and finally the masking layer (6) is removed to obtain a product as shown in D).

In addition, as shown in FIG. 13(C), the base layer (4) and the external light absorbing layer (5) are arranged at a portion (11a) with a large downward slope.
When forming only the masking layer (6), the viscosity of the paint etc. used to form the two layers may be lowered and both may be completely penetrated, or when forming the entire masking layer (6) (see Figure 14 (A)) The edge may be slightly depressed to mask the upper part (11b). In addition, as shown in FIG. 16(B), the external light absorbing layer (
5) In order to provide only the lower part (11a) K, the viscosity is increased when forming the base layer (4), and the viscosity is lowered when the entire external light absorbing layer (5) is formed. ra. In addition, when forming an external light absorbing layer (5) as a transparent material base layer (4) with a low refractive index, total reflection will not occur if the inclination angle of the total reflection surface (11) becomes small. There is a thing. For example, if the substrate is made of acrylic resin (refractive index 1.49) and the underlayer (4) has a refractive index of 14, total reflection will not occur if the inclination of the total reflection surface is 70° or less. It is necessary to take these points into consideration. This case can be solved by forming it as shown in FIG. 13(C).

Acrylic resin is most suitable as the base material for use in the transmission screen of the present invention, since acrylic resin is superior in terms of mechanical properties and moldability. but.

Instead of this, vinyl chloride resin, polycarbonate resin, styrene resin, etc. can also be used. When using these synthetic resin materials, extrusion molding, hot pressing, or injection molding can be used to process All transmission screens according to the invention can be manufactured.

Further, in order to further improve the light diffusivity of the transmission screen according to the present invention, VC is added to a synthetic resin as a base material, such as an acrylic resin, with 5i02. CaCO3°At20-3.
One or more types of additives such as TiO2, BaSO4, ZnO, glass fine powder, or a diffusing substance that does not undergo any chemical change or melting in the liquid synthetic resin medium may be uniformly mixed into the entire medium. It is also effective to adjust the color tone by coloring the base material. Furthermore, it is also effective to perform fine matting treatment on the projection surface (A) and/or the observation surface (B).

Note that the transparent material with a low refractive index used as the base layer (4) may vary depending on the resin used as the base material, but fluorine-based resins, silicon-based resins, etc. may be used. The paint used to form the entire external light absorbing layer (4) is a dark color paint with good adhesion, such as acrylic paint, vinyl chloride paint, or vinyl chloride-vinyl vinegar paint. For the masking layer (6) used to form these layers, a water-soluble resin or an acid- or alkali-soluble ink can be used.

(Example) Example 1 Acrylic resin with a refractive index of 149? 5102f, 2597 with an average particle size of 4μ is used as a diffusing agent during the production of resin plates.
A acrylic resin sheet metal with a thickness of 3 m was prepared, with the acrylic resin mixed in per m''. This acrylic resin plate was used to form a mold with a Fresnel lens surface with a focal length f = 1.1, and a lens unit as shown in Fig. 15 (A). It is sandwiched between a mold made in advance and heated at a temperature of 180°C for 6 minutes, and a pressure cuff is formed.
A transparent screen as shown in Fig. 2 was produced by heat pressing under the conditions of K910n''. Fig. 15 (A)
is the unit of numerical value without metrology f'lvm in R
1 curvature radius n l 5 wa, α1 to the curvature radius of R2
It was mm. For comparison, a screen having a lens unit shaped as shown in FIG. 15(B) was manufactured using the same materials and conditions. , (R1 at this time was the same and 05-5R2 was the same <Q, 1 seaweed.) Thus obtained n2
When the entire luminance distribution of the two screens was measured, the results shown in FIG. 16 were obtained. (This brightness distribution was obtained by calculating the ratio when the front brightness gold was set to 1.) As can be seen from this figure ↓, it was confirmed that the uninvented product could emit the principal at an angle of 40 degrees or more. .

Example 2 A screen having the lens unit shown in FIG. 17 (A>) was manufactured using the same material and under the same conditions as Example 1.

For comparison, a complete screen with a lens unit as shown in the same figure (B) was manufactured.

When the brightness distribution of the obtained n'rc screen was completely measured,
The results shown in FIG. 18 were obtained, confirming the superiority of the product of the present invention.

(Effects of the Invention) Since the present invention has the above-described configuration, it has the advantage of providing a transmission screen that has a large viewing angle and that can be adjusted.

[Brief explanation of the drawing]

1 to 4 are partial perspective views showing water-containing embodiments of the present invention, FIGS. 5 to 8 are partial sectional views showing other embodiments, and FIG. The figure shows an explanatory diagram of the optical path going straight to the lenticular lens, Figures 10 (A) and (B).
is an explanatory diagram of the original output state where it goes straight to the total reflection surface and is incident,
11 and 12 are fully enlarged sectional views of the lens unit in the embodiment of the present invention, and FIGS. 13(A) to (C)
14(A) to 14(D) are schematic process diagrams for forming an external light absorbing layer, and FIG. 15 is an example. Enlarged view of the lens unit of the inventive product used in 1 and the comparative product, same as Fig. 16.
Graph showing the measurement results of Example 1, No. i 7t9 (A)
, (B) Enlarged view of the lens units of the inventive product and comparative product in Example 2, Figure 18 is the same (graph showing the measurement results of Example 2, Figure 19 is the optical path of the conventional optical/ticular lens) 20 is a graph similarly showing the optical characteristics. (A)...Projection side (B)... Observation rule 1 (1)... Lens unit (11)... Total reflection surface (12)... Curved surface part (13)...Central curved surface part (2)...Other curved surface parts (3) @...-Fist Fresnel lens (4)...Base layer (5)... ...External light absorption layer (6) ...Mask layer 1 concave hair 2 figures 3 circles

Claims (1)

[Claims] 1. In a transmission screen equipped with a projection surface and an observation surface, a lenticular lens extending in the vertical direction is formed on the observation surface, and furthermore, lenticular lenses are formed on both sides of the lens unit constituting the lenticular lens. A total reflection surface is formed that totally reflects the light incident on this part and exits from the curved surface part of the top surface, and each total reflection surface is composed of two or more surfaces with different slopes. Transparent lid screen featuring. 2. The transmission screen according to claim 1, characterized in that a central curved surface portion is formed between the curved surface portions. 3. Claim 1 or 2, characterized in that the two or more surfaces with different inclinations are linear surfaces.
Transmissive screen as described in section. 4. Claim 1, characterized in that the two or more surfaces with different inclinations are composed of a straight surface and a curved surface.
The transmission screen according to item 1 or 2. 5. Claims 1, 2 and 2, characterized in that an external light absorbing layer is formed on the total reflection surface via a base layer so as not to impair the total reflection function. The transmission screen according to item 3 or 4. 6. The transmission screen according to claim 5, wherein the underlayer is a transparent material having a lower refractive index than the base material of the screen. 7. The transmission screen according to claim 5, wherein the base layer is a metal reflective layer. 8. Claims 1, 2, 3, and 4, characterized in that a Fresnel lens is formed on the projection surface.
The transmission screen according to item 5, 6 or 7. 9. Claims 1, 2, 3, 4, 5, 6, 7, or 9, characterized in that the base material contains a diffusing agent. Transmissive screen according to item 8. 10. Claims 1, 2, 3, 4, 5, and 6, characterized in that the base material is colored.
9. The transmission screen according to item 7, item 8, or item 9. 11. Claims 1, 2, 3, 4, 5, and 6, characterized in that the projection surface and/or observation surface is subjected to matting treatment. , Section 7, Section 8
The transmission screen according to item 1, 9 or 10.