JP2742780B2 - Transmission prism screen and projection system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive screen suitable for use in a projection television or the like.

[0002]

2. Description of the Related Art Projection televisions, video projectors and the like have conventionally used transmission type screens. FIG. 10 is a schematic plan sectional view illustrating the structure of a conventional transmission screen. The transmission screen shown in FIG. 10 has a Fresnel lens sheet 1 in the order of incidence of light.
And a lenticular lens sheet 2. The Fresnel lens sheet 1 is for converting light from a projector such as a cathode ray tube into substantially parallel light. In addition, the lenticular lens sheet 2 is optically equivalent to arranging a large number of cylindrical lenses that are long in the vertical direction or the horizontal direction, and widens the light to increase the horizontal or vertical viewing angle. Has been used for.

FIG. 11 is a view showing the light directivity of a conventional transmission screen as shown in FIG. In FIG. 11, the horizontal axis represents the viewing angle, and the vertical axis represents the brightness. In a conventional projection television or the like, an image is designed so as to be best viewed by an observer standing in front of a screen. That is, as shown by the solid line in FIG. 11, the image looks brightest at a viewing angle of 0 °, that is, in the normal direction of the screen.

[0004]

The projection type TV systems such as projection televisions are gradually entering into a full-fledged period of use, since the disadvantages such as "images are dark and difficult to see" are gradually solved. At the same time, a new type of system that has not existed in the past has been studied. One such newly considered type of system is a horizontally mounted television. This is a system in which the screen is leveled by, for example, fitting the screen on the surface of a table or the like, and the screen is viewed obliquely from above while sitting on a sofa or the like.

In such a horizontally installed television, since the screen is viewed obliquely from above, it is naturally preferable that the brightness at a viewing angle in this direction is large. On the other hand, since there is little case where the viewing angle is 0 degree, that is, when the screen is viewed from directly above, the brightness in this direction may be small. That is, FIG.
It is necessary to achieve light directivity as shown by a dotted line in FIG. The present invention has been made to solve such a problem, and has as its object to have a large light directivity in a direction with a large viewing angle.

[0006]

According to a first aspect of the present invention, there is provided a sheet-type transmissive prism screen disposed on a projection surface, wherein an optical axis direction is a height direction. become such pyramidal or conical recesses have a prism sheet formed large number segmented into a surface of the emission side, the light is concave incident normal to the prism sheet
Vortex through the slope of the adjacent recess after reflecting on the slope of the part
By being configured to emit, at 0 degree viewing angle
As the brightness takes the minimum value and the viewing angle increases,
It has a light directivity that becomes brighter . Similarly, in order to solve the above problem, in the invention according to claim 2, in the configuration according to claim 1, all the concave portions are in the shape of a regular polygonal pyramid having the same dimensions and shape. Similarly, in order to solve the above-described problem, the invention according to claim 3 is the configuration according to claim 1, wherein the concave portion is formed of two types of triangular pyramids, and the first type of concave portion is formed in the height direction. And two slopes that are substantially perpendicular to each other at an angle of 0 ° to 20 ° with respect to the first direction.
And one and two slopes substantially perpendicular to each other at an angle within 20 degrees from one another, and the one slope of the first kind of recess is the one substantially vertical of the second kind of recess. And the two slopes of the second type of recess are opposed to the two substantially vertical surfaces of the first type of recess. Similarly, in order to solve the above problem, in the invention according to claim 4, in the structure of claim 1, 2, or 3, the prism sheet is formed of a translucent resin and manufactured by a molding method using a mold. It has a configuration that is performed. Similarly, in order to solve the above problem, the invention according to claim 5 is directed to a projector for projecting an image on a horizontal projection surface, and the projector according to claims 1, 2, 3, or 4 disposed at the position of the projection surface. And a transmission system having a transmission prism screen.

[0007]

Embodiments of the present invention will be described below. FIG. 1 is a schematic side sectional view of a transmission type prism screen according to a first embodiment of the present invention, and FIG.
FIG. 3 is a schematic plan view of a prism sheet viewed from above in the transmission prism screen of FIG. 3, FIG. 3 is a schematic cross-sectional view illustrating the operation of the transmission prism screen of FIG. 1, and FIG. 4 is an operation of the transmission prism screen of FIG. FIG. 5 is a diagram illustrating the light directivity of the transmission prism screen of FIG.

The transmission type prism screen shown in FIG.
The Fresnel lens sheet 1 and the prism sheet 3 are arranged in the order of light incidence. This transmissive prism screen is arranged in a horizontal posture, and light is incident from below on a vertical optical axis.

First, as the Fresnel lens sheet 1,
This is for converting the light into substantially parallel light as in the related art, and the same as the related art can be used. Note that if an optical element such as a collimator lens for converting light into substantially parallel light is disposed on the incident side of the screen, the Fresnel lens sheet 1 is unnecessary.

Next, the prism sheet 3 forms a major feature of the transmission type prism screen of the present embodiment. Like the Fresnel lens sheet 1, the prism sheet 3 is a thin plate-shaped member formed entirely of a translucent material. The Fresnel lens sheet 1 and the prism sheet 3 are fixed by screwing ends or attaching tape. In some cases, both are adhered with a translucent organic adhesive or the like.

The prism sheet 3 has a large number of concave portions 30 formed on the light exit side surface thereof, as shown in FIG. The recess 30 has a regular triangular pyramid shape such that the optical axis direction is the height direction. All the recesses 30 have the same size, and are densely arranged in a segment shape as shown in FIG.

Next, the operation of the transmission type prism screen of this embodiment will be described with reference to FIGS. As described above, the light incident on the screen from below first enters the Fresnel lens sheet 1, and the light exiting the Fresnel lens sheet 1 becomes substantially parallel light. This light enters the upper prism sheet 3. The incident light reaches the inclined surface 301 of the concave portion 30 and is reflected by the inclined surface 301. The reflected light travels toward the slope 302 of the adjacent recess 30 and passes through the slope 302 and exits.

Here, as shown in FIG. 3, the angle of the inclined surface 301 at which the light incident on the prism sheet 3 first reaches is
If the angle is set such that the light is totally reflected and the angle of the slope 302 of the adjacent recess 30 to which the reflected light reaches is set to an angle within the critical angle, the light is emitted obliquely upward with little loss. Go.

In particular, although different from that of FIG. 3, the angle formed by the slopes 301 and 302 of the adjacent recess 30 is 60 degrees.
If each of the concave portions 30 is formed so as to have a degree, the incident angle to the slope 301 which reaches first becomes 60 degrees. And
The light is also emitted at an emission angle of 60 degrees, goes to the slope 302 of the adjacent recess 30, and enters the slope 302 of the recess 30 at an incidence angle of 0 degree. Accordingly, light is theoretically transmitted through all the inclined surfaces 302 and is emitted, and the emission angle is 60 degrees with respect to the direction of the optical axis.

That is, in the example shown in FIG. 3, parallel light traveling along the vertical optical axis direction is converted by the prism sheet 3 into light obliquely upward from the horizontal plane by 30 degrees. Therefore, as shown in FIG. 5, the directivity of the emitted light has a minimum brightness at a viewing angle of 0 degree.
Value, the brighter the viewing angle
It is the brightest state near the viewing angle of 60 degrees. For this reason, it becomes very suitable when used in a horizontal installation type projection television or the like in which the screen is viewed obliquely from above. At this time, in the present embodiment, the concave portion 3 having a regular triangular pyramid shape is used.
0, the light emitted from the screen is
In the horizontal direction, it has directivity in six directions.

To explain this point in more detail, as shown in FIG. 4, the light reflected on the inclined surface 301 has directivity in the direction A, and the light reflected on the inclined surface 302 has directivity in the direction B. The light reflected on 303 has directivity in the direction C,
The light reflected on the slope 304 has directivity in the direction D, and the light reflected on the slope 305 has directionality in the direction E.
6 has directivity in the direction F. Therefore, the display is bright and easy to see from any of the six directions obliquely above the screen. In FIG. 4, the slopes 301, 303, 30
5 forms one recess.

In this embodiment, the lenticular lens sheet 2 conventionally used is not used. This is because the prism sheet 3 in the present embodiment can more effectively perform the function of the lenticular lens sheet for spreading the light in the horizontal direction, and the prism sheet 3 becomes a substitute for the lenticular lens sheet. However, the invention of each claim does not exclude the use of a lenticular lens.

In the operation of the above-described prism sheet 3, the point that the concave portion 30 in the shape of a regular quadrangular pyramid is formed on the exit side surface is effective for directing the incident light beam to a large viewing angle without loss. That is, as shown in FIG.
The luminous flux converted into substantially parallel light by the Fresnel lens sheet 1 is incident on the prism sheet 3 and the inclined surface 301 of the concave portion 30.
To reflect. Then, the reflected light flux is transmitted to the adjacent recess 30.
At this time, the reflected light beam travels slightly obliquely above the horizontal direction. In this case, assuming that the light beam has a width that is the full width of the first slope 301 and is reflected at a portion of this width , the slope 302 of the adjacent recess 30 is assumed.
Is always larger than the width of the front slope 301.
It will be. Therefore, all the light beams reflected on the first inclined surface 301 are in principle located in the adjacent concave portion 3. Therefore, in principle, all light beams reflected on the first inclined surface 301 enter within the width of the inclined surface 302 of the adjacent concave portion 30 and pass through the same.

If the light in the vertical direction is simply converted into light in the obliquely upward direction, the conical concave portion may be formed on the surface on the incident side. However, in this case, the width of the luminous flux reflected to the full width of the first slope is always larger than the width of the slope when entering the adjacent slope. Therefore, the light beams at both end portions protrude from the slope and undergo complicated refraction, and only that portion is lost.

Further, when a conical convex portion is formed on the incident side surface instead of the concave portion, it is almost optically equivalent to the configuration of the embodiment. However, reflection occurs when the light passes through the surface on the emission side, and loss is inevitable at this portion. Further, such a sheet-like optical element is easy to manufacture by a compression molding method or an ultraviolet curing method, but molding a mold having a large number of convex portions on the surface has a mold having a large number of concave portions. It is very difficult because it must be made. Therefore, the embodiment is also excellent in terms of ease of mold production. In addition, the configuration in which the conical convex portion is formed on the exit side surface is almost equivalent to the configuration in which the concave portion is formed on the incident side surface, and is disadvantageous in that light loss is large.

Although the medium in the internal space of the concave portion 30 of the prism sheet 3 of the present embodiment is air, the concave portion 30 may be filled with a material having a different refractive index from that of the prism sheet 3. In particular, it is also possible to obtain the effect of a black stripe by clearing the color by filling the concave portion 30 with a certain depth with a black paint or the like. When the prism sheet 3 is directly exposed,
Since there is a problem that dust may accumulate in the concave portion 30, the light emitting side of the prism sheet 3 may be covered with a translucent cover.

Next, examples of the transmission type prism screen belonging to the above embodiment will be described below. First, the Fresnel lens sheet 1 and the prism sheet 3
It is manufactured by a compression molding method or an ultraviolet curing method using a translucent resin such as acrylic. The entire thickness of the Fresnel lens sheet 1 is 1 to 5 mm, and is formed to be equivalent to a collimator lens having a focal length of, for example, about 700 mm.

The prism sheet 3 has a total thickness of about 1 to 5 mm, and the recess 30 has an opening of 0.1 to 3 mm on one side.
It is a triangular pyramid having a regular triangle of about mm and a height of about 0.1 to 4 mm. The size of the Fresnel lens sheet 1 and the prism sheet 3 is determined by the required size of the screen, but is, for example, about 1 m × 1 m (or 1 m in diameter). Further, the prism sheet 3 may be formed by mixing a light diffusing material such as silicon rubber or the like so that the prism sheet 3 has a light diffusing function.

When the prism sheet 3 is manufactured by the above-described method, a mold is required. However, since the prism sheet 3 of the embodiment may be formed so as to have the recess 30, the mold has the recess 30. A corresponding convex portion will be formed. Such a mold can be manufactured with sufficient accuracy by cutting.

Next, a second embodiment of the present invention will be described. FIG. 6 is a schematic side sectional view of a transmission type prism screen according to a second embodiment of the present invention, and FIG. 7 is a schematic perspective view of a prism sheet in the transmission type prism screen of FIG.

The transmission type prism screen of this embodiment also has a configuration in which the Fresnel lens sheet 1 and the prism sheet 3 are superposed and adhered in the order of incidence of light, similarly to the first embodiment. The transmission type screen of this embodiment is different from that of the first embodiment in that the shape of the concave portion 30 formed in the prism sheet 3 is a regular quadrangular pyramid.

In the second embodiment, as in the first embodiment, light can be emitted with a large directivity in an obliquely upward direction with a large viewing angle. In this case, since there are four types of slope directions, the distribution is such that the light directivity increases in four directions of front, rear, left and right in the horizontal direction.

Next, a third embodiment of the present invention will be described. FIG. 8 is a plan partial schematic view of a prism sheet used in a transmission type prism screen according to a third embodiment of the present invention, as viewed from above.

The transmission type prism screen of this embodiment also has a configuration in which the Fresnel lens sheet 1 and the prism sheet 3 are superposed and adhered in the order of incidence of light, similarly to the first embodiment. The feature of the transmission type screen of this embodiment is that the shape of the concave portion formed in the prism sheet 3 is triangular pyramid like the first embodiment, but it is not a regular triangular pyramid but a triangular shape having an eccentric apex angle. It is a point that is conical.

That is, as shown in FIG. 8, the prism sheet of this embodiment is made of two types of triangular pyramids, and the first type of concave portion 32 has a height of 0 in the height direction.
It consists of two substantially perpendicular surfaces having an angle within 20 degrees from one degree and one slope, and the second kind of concave portion 33 has
Similarly, it is of a second type consisting of one and two slopes which are substantially perpendicular to the height direction at an angle within 0 to 20 degrees. Then, as shown in FIG.
Is arranged so as to face one substantially vertical surface of one of the second type of recesses 33, and the second type of recesses 33
Are arranged so as to oppose the substantially vertical surfaces of the two recesses 32 of the first type.

In the transmission type prism screen of the third embodiment having the above-described configuration, similarly to the first embodiment, light can be emitted with a large directivity in an obliquely upward direction having a large viewing angle. And in this third embodiment,
Six directivities in the horizontal direction in the first embodiment (A,
B, C, D, E, and F) have directivity only in three directions on one side. That is, as shown in FIG. 8, the directivity of the light emitted from the screen in the horizontal direction is determined by the directivity G of the light reflected on one slope of the first type of recess 32 and the second type of recess 33. The directivity H of the light reflected on the two slopes of
I. The reason why the substantially perpendicular plane is limited to within 20 degrees with respect to the height direction is that if it is too large, the directivity increases in directions other than the above three directions G, H, and I. .

The configuration of the second embodiment is particularly preferable when the viewer is located on one side of the horizontal projection plane. For example, in a video game machine or the like, a person sits in front of a horizontal screen and looks at the screen only from this direction. In this case, the screen only needs to be seen well from the side on which the person sits, and may not be easily seen from the other side. Therefore, it is preferable to use a screen having the above configuration, since the screen can be viewed extremely brightly from one side.

In FIG. 8, two types of recesses 32 and 3 are shown.
3 is formed such that the shape of the opening is an equilateral triangle, but is not limited to this, and it is a matter of course that other shapes such as an isosceles triangle may be used. In particular, if the apex angle of the isosceles triangle is appropriately changed, the angle formed by the two slopes of the second kind of concave portion 33 is changed. Therefore, by appropriately selecting the apex angle of the opening, the three directivities G, shown in FIG.
The spread angles of H and I can be adjusted.

Next, still another embodiment of the transmission type prism screen of the present invention will be briefly described. In the description of the first and second embodiments, the case where the concave portions 30 and 31 of the prism sheet 3 have the shape of a regular triangular pyramid or the shape of a regular quadrangular pyramid is described. For example, a regular pentagonal pyramid, a regular hexagonal pyramid, or the like may be used as those having the same effects as those of the first or second embodiment. further,
It can also be implemented with a conical recess.

If the distribution of light directivity in the horizontal direction may be non-uniform, it may be a pyramid other than a regular pyramid.
Note that the term “pyramid” does not have a strict meaning in any case, and in actual products, slopes and ridges may be rounded and curved. For the same purpose, the concave portion may have a round bottom (conical tip). In particular, when the concave surface is formed so that the inclined surface is a part of a spherical surface or a cylindrical surface, the directionality of light emitted from the screen can be considerably widened. For example, when a cutting tool having an arc-shaped tip is used in manufacturing a mold for molding, the shape of the slope of the concave portion becomes a cylindrical surface convex outward in the concave portion.

The important thing about the arrangement of the concave portion for reducing the loss of light is that as shown in FIGS. 2, 7 and 8,
It is important that the slopes of each of the recesses 30, 31, 32, 33 always face each other. This is because, when the slopes face each other, light reflected on one slope is transmitted through the other slope and emitted without loss.

Incidentally, such recesses 30, 31, 32, 3
The fact that all three have the same size is not an essential requirement for the invention of claim 1. The present invention can be implemented even when the sizes are slightly different. However, it is necessary to pay attention to the use of concave portions having greatly different sizes, since there is a problem that the loss of light when passing through the adjacent slope is increased.

The meaning of the terms “prism sheet” and “prism screen” will be supplementarily explained.
“Prism sheet” means a sheet-like optical element in which a large number of prisms are arranged in a segment shape, and “prism screen” means a screen using such a prism sheet. As the inventor recognizes, there is no transmission screen adopting such a structure in the past. Therefore, the name of “transmission prism screen” itself is new.

Next, an embodiment of the invention of a projection system using the transmission type prism screen of each of the above embodiments will be described. FIG. 9 is a schematic configuration diagram of an embodiment of the projection system of the present invention. The projection system shown in FIG.
It comprises a rectangular parallelepiped casing 4, a transmissive prism screen 5 fitted on the upper surface of the casing 4, a projector 6 for projecting an image on the transmissive prism screen 5, and the like.

The casing 4 is arranged so that the upper surface 40 is horizontal. The upper surface 40 is provided with an opening conforming to the size and shape of the transmission type prism screen 5, and the transmission type prism screen 5 is fitted into this opening. Note that a protective cover plate 7 is fitted over the transmission type prism screen 5. This protective cover plate 7 is for protecting the transmission type prism screen from scratches and the like.

As the transmission type prism screen 5, any one of the embodiments described above is employed. The size is, for example, about 1 m × 1 m (about 1 m in diameter in the case of a circle). As the projector 6, a cathode ray tube, a liquid crystal display, or the like is used. The light from the projector 6 is projected onto the transmission prism screen 5 via the plane reflecting mirror 8.

According to the projection system having the above configuration, since the transmission type prism screen 5 of the above-described embodiment is used, the screen is bright and easy to see when the screen is viewed from obliquely above at a large viewing angle. . Therefore, the configuration is particularly suitable as a horizontal installation type projection television, video projector, or the like.

[0043]

As described above, according to the transmission type prism screen of the first aspect of the present invention, a screen having a large light directivity in a direction of a large viewing angle can be constructed, and the projection plane is set horizontally. In addition to this, a bright screen with little loss of light can be obtained. Also,
According to the transmission type prism screen of the second aspect, in addition to the effect of the first aspect, the light directivity distribution of the emitted light in the horizontal direction becomes uniform, which is suitable for a case where a screen placed horizontally is viewed and viewed. It becomes something. According to the transmission type prism screen of the third aspect, in addition to the effect of the first aspect, the light directivity distribution in the horizontal direction of the outgoing light is extremely large only on a specific side, so that it is placed horizontally. This is extremely suitable when the screen is viewed exclusively from a specific side. Further, according to the transmission type prism screen of claim 4, it is possible to mass-produce the transmission type prism screen of claim 1, 2, 3, or 4 at low cost. Further, according to the projection system of the fifth aspect, the first, second, and third aspects of the invention are applicable.
Or, while obtaining the effect of 4, an image can be projected on a horizontal projection surface and viewed, and the demand for a projection television or the like can be further expanded by providing a new type of system.

[Brief description of the drawings]

FIG. 1 is a schematic side sectional view of a transmission type prism screen according to a first embodiment of the present invention.

FIG. 2 is a schematic plan view of a prism sheet in the transmission prism screen of FIG. 1 as viewed from above.

FIG. 3 is a schematic sectional view illustrating the operation of the transmission type prism screen of FIG. 1;

FIG. 4 is a schematic plan view illustrating the operation of the transmission type prism screen of FIG. 1;

FIG. 5 is a diagram illustrating the light directivity of the transmission prism screen of FIG. 1;

FIG. 6 is a schematic side sectional view of a transmission type prism screen according to a second embodiment of the present invention.

FIG. 7 is a schematic perspective view of a prism sheet of the transmission type prism screen of FIG. 6;

FIG. 8 is a schematic plan view of a top view of a prism sheet used in a transmission type prism screen according to a third embodiment of the present invention.

FIG. 9 is a schematic configuration diagram of an embodiment of a projection system of the present invention.

FIG. 10 is a schematic plan sectional view illustrating the structure of a conventional transmission screen.

FIG. 11 is a diagram showing the light directivity of the conventional transmission screen as shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fresnel lens sheet 3 Prism sheet 30 Depression 31 Depression 32 First type depression 33 Second type depression

Claims (5)

(57) [Claims] 1. A sheet-type transmissive prism screen disposed on a projection surface, wherein a number of pyramidal or conical concave portions whose optical axis direction is a height direction are formed in a segment shape on a surface on an emission side. the prism sheet is formed with perforated, pre
Light perpendicular to the stimulus sheet reflected on the slope of the recess
Later, it is configured to transmit through the slope of the adjacent recess and emit it.
The minimum brightness at 0 ° viewing angle
Light directivity that becomes brighter as the viewing angle increases
A transmissive prism screen characterized in that it has a characteristic. 2. The transmissive prism screen according to claim 2, wherein all of the concave portions have a regular polygonal pyramid shape having the same dimensions and shape. 3. The concave portion is formed of two types of triangular pyramids, and the first type of concave portion has two surfaces that are substantially perpendicular to the height direction at an angle of 0 to 20 degrees. And one slope, and the second kind of recess is
Similarly, it comprises one and two slopes which are substantially perpendicular to the height direction at an angle of 0 to 20 degrees, and the one slope of the first kind of recess is a second kind. Are disposed so as to face the one substantially vertical surface of the concave portion, and the two slopes of the second type concave portion are disposed so as to face the two substantially vertical surfaces of the first type concave portion. The transmission type prism screen according to claim 1, wherein: 4. The transmissive prism screen according to claim 1, wherein said prism sheet is formed of a translucent resin and is manufactured by a molding method using a mold. 5. A projector for projecting an image on a horizontal projection surface, and a transmission type prism screen according to claim 1, 2, 3 or 4 arranged at the position of the projection surface. Projection system.