JPH08314016A - Picture projection screen and its production - Google Patents

Abstract

PURPOSE: To accurately form a black stripe all over the area of the non light-emitting part of a picture projection screen by forming a nearly trapezoidal protruding part in the non light-emitting area of a light-emitting part and providing a light absorbing part at the upper surface part and the side surface part of the protruding part. CONSTITUTION: The nearly trapezoidal protruding part 5 is formed in the non light- emitting area of the light-emitting surface and the light absorbing part 4 is provided at the upper surface part 5a and the side surface part 5b of the protruding part 5, then a minute recessed part 6 is formed on a boundary between the protruding part 5 and an aperture part 3. By utilizing the minute recessed part 6, the black stripe is formed not only on the upper surface 5a but also on the side surface 5b of the protruding part 5. Since the light absorbing part 4 is provided at the side surface part 5b, it is largely secured without narrowing the aperture part 3, and external light is effectively absorbed to improve contrast further. Especially, absorptance to the external light made incident at a large angle equal to or above a tilt angle gets larger than the absorptance to external light made incident from the vicinity of a front, so that a higher contrast improving effect is achieved under such external light environment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection screen used in an image projection apparatus for projecting an image on a CRT, a liquid crystal panel or the like from the rear side of the screen in an enlarged manner and observing it from the front side, and a method of manufacturing the same.

[0002]

2. Description of the Related Art An image projection screen has a basic function of diffusing projected light so that it can be viewed from a predetermined range on the viewing side.

In order to further reduce the contrast deterioration due to external light reflection while realizing such a basic function, a lenticular lens array is formed on the projection side, and an emission surface is provided on the observation side near the focal point thereof and the emission surface is provided. In general, a stripe-shaped light absorbing portion (hereinafter referred to as a black stripe) is provided in a region where the projected light does not pass.

A cross-sectional view of such a configuration is shown in FIG. 3 along with ray tracing. FIG. 3 shows a lenticular screen (image projection screen), and the projection light incident on the lenticular lens 2 is refracted by the lens action and converges on its focus. At this time, since the projected light has a slight diffusivity, the opening 3 is provided so as to obtain a sufficient transmission efficiency (for example, 90% or more) in consideration of this, and the black is provided in the other non-emission areas. The stripe 4 is provided.

In this way, the projection light can be diffused by the action of the projection-side lenticular lens, and the reflection of external light can be effectively reduced without the loss of the projection light. Can be improved.

At this time, as apparent from FIG. 3, the black stripe must be formed at an accurate position corresponding to the projection side lenticular lens. This is because when the black stripe is applied to the emission area of the projected light, the projected light is absorbed and the brightness is significantly impaired.

The screen size of this type of device, typically a rear projection television, is typically 40 to 70 inches, while the lenticular lens pitch is 0.5 to 1.0.
mm, and in normal screen printing, a large positional deviation occurs due to a positioning error between the plate and the lenticular lens sheet and a pitch error due to a difference in expansion coefficient between the two.

Conventionally, in order to accurately form a black stripe, when molding a lenticular lens sheet,
In general, a convex portion is integrally formed in the non-emission area of the emission surface together with the shape of the incident surface lens, and the light absorbing material is printed on the convex surface. A cross-sectional view of the screen thus formed is shown in FIG.

The convex portion 5 is formed by the upper surface 5a and the side surface 5b, and the black stripe 4 is selectively formed only on the upper surface 5a by transfer or printing.

By doing so, the comparison can be performed without causing a positional deviation due to a positional error between the plate and the lenticular lens sheet or a pitch error due to a difference in expansion coefficient between the plate and the lenticular lens sheet, which is a problem when simply performing screen printing. The black stripe can be formed accurately.

[0011]

In such a conventional technique, the height h of the convex portion 5 is set to about 50 to 100 micrometers in order to prevent the light absorbing material from adhering to the opening 3. . The inclination angle of the side surface portion 5b is set to about 5 to 15 degrees in order to prevent draft at the time of molding and vignetting of light emitted at a large angle. For example, height h
Is 100 micrometers and the tilt angle θ is 10 degrees, the width d of the side surface portion 5b is about 18 micrometers, and if the pitch is 0.5 mm, 36 micrometers, or about 7% of the width d is the side surface portion 5b. Will be a problem.

Since the projection light incident on the side surface portion 5b is totally reflected and absorbed by the black stripe, this portion cannot be used as an effective emission area. On the other hand, there is no effect of absorbing external light, and therefore it does not contribute to the improvement of contrast. Therefore, there is a problem in that this portion becomes a dead space that does not function effectively, and it is not possible to make the most of the contrast improvement by the black stripe.

[0013]

In order to solve the above-mentioned problems, the image projection screen of the present invention is such that a substantially trapezoidal convex portion is formed in the non-emission area of the emission surface, and the upper surface portion and the side surface portion thereof are formed. A method of manufacturing an image projection screen of the present invention, which is provided with a light absorbing portion and effectively realizes the light absorbing portion, forms a lenticular lens sheet having a minute concave portion at the boundary between the substantially trapezoidal convex portion and the emission region. Then, the lenticular lens sheet is installed with the surface having the substantially trapezoidal portion upward, and a light-absorbing material is applied to the surface having the substantially trapezoidal portion, and light is applied to the upper surface and the side surface portion of the substantially trapezoidal portion. It forms an absorption layer.

[0014]

By using such an image projection screen, the entire emission surface can be used as an effective surface of the emission area or the external light absorption area, and the effect of improving the contrast can be maximized. Further, according to the method of manufacturing the image projection device of the present invention, such an image projection screen can be realized easily with high accuracy.

[0015]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the image projection screen of the present invention. FIG. 1 is similar to FIG. 4 showing a conventional image projection screen, and parts having similar functions are given the same reference numerals, but the side surface part 5 of the convex part 5 is shown.
b is also provided with the light absorbing portion 4, and the convex portion 5 and the opening portion 3 are provided.
The feature is that the minute recessed portion 6 is provided at the boundary of.

Since the side surface portion 5b is also provided with the light absorbing portion, the light absorbing portion can be made large without narrowing the opening, and external light can be effectively absorbed to further improve the contrast. In particular, since the absorptance for external light incident at a large angle equal to or greater than the inclination angle is greater than the absorptance for external light incident from the front vicinity, a greater contrast improving effect is exhibited in such an external light environment.

The minute recesses 6 are provided in order to manufacture such an image projection screen of the present invention accurately and simply, and a method of manufacturing the image projection screen of the present invention will be described below.

FIG. 2 is a process chart showing an embodiment of the method of manufacturing the image projection screen of the present invention.

First, a lenticular lens array is provided on one surface, and a substantially trapezoidal convex portion 5 is provided in the non-emission area on the opposite surface.
The lenticular lens sheet having the microscopic concave portions 6 at the boundary between the substantially trapezoidal convex portion 5 and the emission region is formed.

Next, the lenticular lens sheet is placed with the surface having the substantially trapezoidal convex portions 5 upward, and the light absorbing material is applied by screen printing with a solid plate.

At this time, the upper surface portion 5 of the substantially trapezoidal convex portion 5 is formed.
Material viscosity, printing conditions, etc. are adjusted so that the light-absorbing material will not only enter a but also the side surface portion 5b.

Finally, the solvent is removed by drying to fix the amount of the light absorbing material, and the process is completed. By doing so, the excess portion of the amount of the light absorbing material that has sneaked into the side surface portion 5b is accumulated in the minute concave portion 6 provided at the boundary between the substantially trapezoidal convex portion 5 and the opening portion and does not protrude to the opening portion. It is possible to prevent this, and it is possible to accurately form the light absorbing layer on the side surface under a wide range of printing conditions.

[0024]

As will be apparent from the detailed description above, by using the image projection screen of the present invention, maximum reflection of external light can be realized while ensuring the transmission efficiency of projection light, and bright and high contrast is achieved. An image projection device can be realized.

Further, by using the method for manufacturing the image projection screen of the present invention, the entire non-emission part can be accurately and simply used as the light absorption part while leaving the opening part.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an image projection screen of the present invention.

FIG. 2 is a process chart showing an embodiment of a method for manufacturing an image projection screen according to the present invention.

FIG. 3 is a sectional view showing the function of a lenticular lens.

FIG. 4 is a sectional view showing a conventional image projection screen.

[Explanation of symbols]

 1 Image Projection Screen 2 Lenticular Lens 3 Opening 4 Black Stripe 5 Convex 5a Convex Top 5b Convex Side 6 Small Recess 6

Claims (3)

[Claims] 1. A rear projection screen for projecting an image from the back side and observing from the front side, wherein the projection side has a lenticular lens array, and the non-emission region on the observation side has a substantially trapezoidal convex portion. An image projection screen having a light absorbing layer formed on the upper surface and the side surface of a trapezoidal convex portion. 2. The image projection screen according to claim 1, wherein a minute concave portion is provided at a boundary between the substantially trapezoidal convex portion and the emission area. 3. A method of manufacturing a rear projection screen for projecting an image from the rear surface and observing the image from the front surface, wherein a lenticular lens array is provided on the projection side, and a substantially trapezoidal convex portion is provided in the non-emission area on the observation side. Having a step of forming a lenticular lens sheet having minute recesses at the boundary between the substantially trapezoidal convex portion and the emission region, and setting the surface of the lenticular lens sheet having the substantially trapezoidal convex portion upward. , Applying a light absorbing material to the surface having the substantially trapezoidal convex portion,
A method of manufacturing an image projection screen, comprising the step of forming a light absorbing layer on the upper surface and the side surface of the substantially trapezoidal portion.