JPS63165838A - Transmission type screen - Google Patents

Abstract

PURPOSE:To expand a visual angle and to reduce color shift by specifying an angle formed by two lens faces forming a lenticular lens and a screen face. CONSTITUTION:An inclined angle theta2 formed by the 2nd lens faces 2, 2' and the screen face is > an inclined angle theta1 formed by the 1st lens 1, 1' and the screen face. Even if shifted light is made incident, the light reflected on the lens faces 1, 1' is reflected again by the lens faces 2, 2' and then projected, so that the right and left light quantity values of light beams projected from the screen can be made equal. Consequently, the color shift can be reduced. Since the greater part of the projected light is reflected on the lens faces 1, 1' or 2, 2' and then refractively projected, the output light can be diffused to a wide range and the visual angle can be expanded.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is used in so-called i3 projection televisions, in which images are projected onto a screen from the back side and the images transmitted through the screen are observed from the front side. Regarding transmission screens.

(Prior art) -A. Projection TV uses a Fresnel lens to turn images emitted from a CRT in three colors, red, green, and blue, into nearly parallel light, and then enters the light into a transmissive screen, which allows the screen to view the image. It has a structure that determines the angle.

Conventionally, the transmissive screens used in such projection televisions are those that utilize only light refraction, or those that utilize only light refraction, or those that completely reflect a portion of the light that enters the screen on a portion of the screen before emitting light. There is a format.

(Problems to be Solved by the Invention) However, the former method, which uses only the refraction of light, has a problem in that the horizontal viewing angle can only be increased by about ±50''. The type that emits light after total reflection of the incident light makes it possible to widen the viewing angle more than the former, but it is not possible to shift the incident light to the screen and emit the incident light evenly on the left and right sides. A color shift occurs due to the shifted light that enters the screen due to the fact that the three-color CRT (red, green, and blue) is shifted by about 5 to 10 degrees from the optical axis (a phenomenon in which the colors appear to change when the viewing angle is changed). cannot solve the problem.

(Means for Solving the Problems) The present invention has been made in view of the above points, and provides a transmission screen with a large viewing angle and good color shift.

That is, the present invention provides a transmission screen in which a lenticular lens is formed on the light exit surface side, in which a lens unit constituting the lenticular lens includes a first lens surface that is a total reflection surface protruding toward the light exit surface side; a second lens surface that is a light exit surface or a reflective surface that is connected to the first lens surface; and a third lens surface that is convex toward the light entrance surface that forms a top that is connected to the second lens surface. The object of the present invention is to provide a transmission screen comprising a lens surface, and characterized in that the angle of inclination between the second lens surface and the screen surface is larger than the angle of inclination between the first lens surface and the screen surface.

(Example) Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a diagram showing an example of use of the pass-through screen of the present invention. Images emitted from the three-color CRT 50 of red, green, and blue of the projection television through the projection lens 60 are turned into almost parallel light by the Fresnel convex lens 70, and the parallel light enters the transmissive screen 100 of the present invention and is reflected by the screen 100. The light is emitted and diffused at a certain viewing angle and is observed by the observer.

FIG. 2 shows a partial sectional view of an example of a transmission screen according to the present invention.

On the light exit surface side of the transmissive screen 100, there is a first lens surface 1 which is formed to form an inclination angle θ1 with the screen surface and protrude toward the viewer, and which totally reflects the incident light.
1゛, this first lens surface 1, a second lens surface 2.2°, which is a light emitting surface or a reflecting surface, which is connected to the screen surface at an inclination angle θ with respect to the screen surface; A plurality of lens units 10 each consisting of a second lens surface 2, which is the top part, and a third lens surface 3, which is convex toward the light entrance surface formed between 2' and 2', are arranged in series to form a light output lenticular lens 2.
0 is formed.

Here, each lens surface is symmetrical with respect to the optical axis.

FIG. 3 is a diagram explaining the trajectory of light on the screen of FIG. 2, where the light enters parallel to the optical axis, and the arrow indicates the direction of travel of the light.

Most of the incident light is totally reflected at the first lens surface 1.1°, and the reflected light is refracted and precipitated from the second lens surface 2.2° or the third lens surface 3. Other light is totally reflected by the second lens surface 2.2', and is refracted and precipitated from the third lens surface 3, or exits from the third lens as it is. Therefore, the light emitted from the entire screen is reflected by the first lens and then refracted and emitted by the third lens, so that it can be diffused to a viewing angle of about ±70° and the amount of light relative to the optical axis. Since they are symmetrical, no color shift occurs.

Figure 4 shows the screen shown in Figure 2 at 1 point relative to the optical axis.
It is a diagram illustrating the trajectory of light incident with a 0″ shift,
The arrow indicates the direction of travel of the light.

Most of the incident light enters the first lens surface and is reflected, but the light reflected at part (a) of the first lens surface 1 is refracted to the right in the figure from 1° of the first lens surface. The light that is emitted and reflected at part (b) is totally reflected by the second lens surface 2' and refracted and emitted from the second lens surface 2 or the third lens surface 3 to the left side in the figure, and is further reflected in the part (b). The light reflected at (c) is refracted and exits from the second lens surface 2' from the right side in the figure. Also, the light that enters the first lens surface l is totally reflected,
The light is refracted and emitted from the second lens surface 2 or the third lens surface 3 to the left side in the figure. Here, the amount of light that enters the first lens surface l is approximately twice the amount of light that enters the lens surface ↓'', but the amount of light that comes out is the same as the light that is reflected at part (b). In order to emit light to the left side, the left and right sides are blurred.In other words, in the screen of the present invention, the inclination angle θ1 between the first lens surface and the screen surface is smaller than the inclination angle θ1 between the second lens surface and the screen surface. By increasing , the light reflected on the first lens surface can be further reflected on the second lens surface and emitted, and the amount of light that enters the two first total reflection surfaces is different on the left and right sides. However, when the light is emitted, it is possible to emit light to the left and right with almost the same amount of light, thereby reducing color shift.

On the other hand, in a conventional lenticular lens in which there is only one lens surface serving as a total reflection surface as shown in FIG. Since the light is refracted and emitted directly from the total reflection surface 6' or the light emitting surface 7, the amount of light emitted from the screen is not equal on the left and right sides, making it impossible to reduce color shift.

In the present invention, the inclination angle θ1 of the first lens and the inclination angle θ8 of the second lens are such that the inclination angle θ2 is the inclination angle θ1.
The shift of the incident light should be about 5° to 10°, and the ratio of the pitch of the lens surface forming the top portion to the pitch of one lenticular lens should be 0.1 to 0.5°.
3, the inclination angle θ of the first lens is 55
@~85″, second lens inclination angle θ2 is 70°~9
It is desirable that the angle be 0°.

For example, if the material of the screen is acrylic (refractive index 1.49)
), the light having an incident angle of 42@ or more is totally reflected, so the inclination angle θ1 of the first lens is about 75°, and the inclination angle θyo of the second lens is about 85@.

Further, the cross-sectional shape of each lens surface is a circle, an ellipse, a curve that is part of a parabola, or a straight line.

FIG. 6 is a partial sectional view of another embodiment of the transmission screen of the present invention.

The transmission screen of the present invention basically has the above configuration, but as shown in FIG.
．． A light-shielding layer 8 is provided 1° above the light-emitting surface to prevent unnecessary light from entering or reflecting from the light-emitting surface side, thereby reducing a decrease in contrast in a bright room. In this case, since no light is emitted from the first lens surface, the characteristics of the lens will not be impaired even if the light shielding layer 8 is provided.

As a material for forming such a light-shielding layer 8, a material obtained by adding a black pigment or a matting agent to a known paint or ink can be used, and the above-mentioned material can be used by ordinary printing means or coating means. Accordingly, the light shielding layer 8 can be formed on the first lens surface.

In addition, if a light reflection layer 1) 9 made of a metal vapor deposition layer or the like is provided on the first lens surface 1, 1° as shown in FIG. 7 before forming the light shielding layer 8, the total reflection surface will reflect the light. This light-reflecting layer 9, which is preferable due to increased efficiency, can be formed by a general metal thin film layer forming method, such as a vacuum evaporation method, a plating method, a sputtering method, an ion-blating method, or the like.

FIG. 8 is a partial perspective view of a screen having vertical light diffusivity, which is another embodiment of the present invention, in which the lenticular lens lO on the light entrance surface side is perpendicular to the lenticular lens lO on the light exit surface side. The shape of this lenticular lens hook is not limited to the one shown in the figure, but can be any shape as long as it has the function of diffusing light in the vertical direction. But that's fine.

Furthermore, by imparting light diffusing properties to the transmissive screen of the present invention, vertical (up and down directions as seen from the viewer)
Alternatively, the emitted light may be diffused.

An example of a method for imparting light diffusing properties to the transmissive screen of the present invention is a method of adding a light diffusing agent inside the transmissive screen. According to this method, fine particles having the property of scattering light, for example, Light is also diffused in the vertical direction by incorporating silica particles, alumina particles, glass powder, resin powder, etc. with a particle size of about 0.5 to 30μ in a ratio of 1 to 10% by weight to the material that makes up the screen. It is possible to obtain a transmissive screen having the following characteristics. If it is necessary to additionally confuse light, it is preferable to use particles that have a different refractive index for light than the material constituting the screen.

Other methods of imparting light diffusing properties to the screen include, for example, attaching a plastic film containing a light diffusing agent to the screen by heat fusing or the like when molding the screen, or There is a method of roughening the surface by sandblasting or using the light-emitting surface as a light-diffusing surface.

The material constituting the transmission screen of the present invention can be of any material as long as it is transparent and can be molded into a sheet, but examples include acrylic resin, polystyrene resin, polyvinyl chloride resin, polycarbonate resin, polyester resin, cellulose resin, etc. Thermoplastic resins, glass, etc. are preferred, and especially when thermoplastic resins are used, screens can be easily and efficiently produced by known molding methods. One example of the manufacturing method is to heat and press a thermoplastic resin sheet using an inverted mold (plate-shaped or roll-shaped) with a predetermined shape; Examples include a method of applying the product immediately after it has not yet been cooled, a casting method using a mold, and other molding methods. Further, the thermoplastic resin sheet may be processed after being cut into about one piece, or a continuous sheet in a wound state may be processed continuously.

The transmissive screen of the present invention has the function of a transmissive projection screen when used alone, but if a Fresnel convex lens is placed on the large light surface side, projection light can be uniformly irradiated to every corner of the screen, making it more effective. It is true.

(Operations and Effects of the Invention) In the transmissive screen of the present invention, since the inclination angle θ2 of the second lens surface is made larger than the inclination angle θ1 formed between the first lens surface and the screen surface, the light is shifted. Even if the light is incident on the lens (even if the amount of light on the left and right sides of the lens is different), the light reflected on the first lens surface can be further reflected on the second lens surface and then emitted, The amount of light emitted from the screen on the left and right sides can be made equal, and color shift can be reduced.

In addition, since the first part of the emitted light is reflected by the first lens surface or the second lens surface and then refracted and emitted, the emitted light can be diffused over a wider range than conventional lenticular lenses, and the viewing angle can be increased. Can be expanded.

Furthermore, since the screen of the preferred embodiment of the present invention has a light-shielding layer on the first lens surface, which is a total reflection surface, there is no unnecessary light incident or reflection from the light-emitting surface, and there is no reduction in contrast even in a bright room. Less can provide good projection TV.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of use of the transmission screen of the present invention,
FIG. 2 is a partial cross-sectional view of an example of the transmissive screen of the present invention, FIGS. 3 and 4 are diagrams showing light trails on the screen of FIG. 2, and FIG. 5 is a diagram showing the light traces on the conventional screen. FIGS. 6 and 7 are partial cross-sectional views of a screen according to another embodiment of the present invention, and FIG. 8 is a partial perspective view of a screen according to another embodiment of the present invention. 1.1°...First lens surface 2.2°-...-Second lens surface 3...-Third lens surface 8-...Light blocking layer 9-Light reflecting layer 10- Lens unit 20.--Outgoing light wrench error lens 30...Light entry wrench error lens 100--Transmissive screen Fig. 1 Fig. 2 Fig. 3 Fig. 5 Fig. 6 Fig. 7 Fig. 8

Claims (6)

[Claims] (1) In a transmission screen in which a lenticular lens is formed on the light exit surface side, the lens unit constituting the lenticular lens includes a first lens surface that is a total reflection surface protruding toward the light exit surface side, and a first lens surface that is a total reflection surface that projects toward the light exit surface side; a second lens surface that is a light exit surface or a reflective surface that is connected to the lens surface of the lens; and a third lens surface that is convex toward the light entrance surface that forms a top that is connected to the second lens surface. What is claimed is: 1. A transmission screen characterized in that the angle of inclination between the second lens surface and the screen surface is greater than the angle of inclination between the first lens surface and the screen surface. (2) The first lens surface and the screen surface have an inclination angle of 55° to 85°, and the second lens surface and the screen surface have an inclination angle of 70° to 90°. A transmission screen according to claim (1). (3) Claims (1) or (2) characterized in that a lenticular lens is provided on the light entrance surface side to diffuse light in a direction perpendicular to the lenticular lens on the light exit surface side. Transparent screen as described. (4) The transmission screen according to any one of claims (1) to (3), characterized in that a light-shielding layer is provided on the first lens surface. (5) A transmission type according to any one of claims (1) to (3), characterized in that a light-shielding layer and a light-reflecting layer are provided in this order on the first lens surface. screen. (6) The transmission screen according to any one of claims (1) to (5), characterized in that a light diffusing agent is added therein.