JP2000347298A - Back face projection screen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screen on which a bright image can be observed in a wide range with a wide horizontal viewing angle and an increased vertical viewing angle by using a lens sheet having a group of lenses arranged on the sheet, with the lenses having a combined cross-sectional form in the vertical direction which has a function to refract the light to project an image in the vertical direction. SOLUTION: The lens sheet which constitutes a back face projection screen has a group of lenses arranged parallel to one another, and the lens group has a combined cross-sectional form in the vertical direction which has a function to refract the light to project an image in the vertical direction. The cross- sectional form of the lens group of the lens sheet 11 is a combined form of sharp tops and straight portions 12 formed by adjacent convex lens elements 11 (Fig a). Or, the lens sheet 20 or 31 has a combined cross-sectional form of sharp ends formed by adjacent convex lens elements with concave lens elements 22 or convex lens elements 32 having a larger radius of curvature than the radius of curvature of the convex lens of the convex lens elements (Fig b, c).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear projection type screen which is used for a transmissive liquid crystal projection television, a liquid crystal display, etc., in which a vertical viewing angle is remarkably improved, and which is bright and allows wide-angle images to be observed.

[0002]

2. Description of the Related Art A rear projection type screen used in an image projection apparatus for magnifying and projecting an image of a projection tube, a liquid crystal panel or the like, superimposing the image on a screen, and observing the image from the front is conventionally used.
As shown in FIG. 4, it is composed of two components: a Fresnel lens and a horizontal lenticular lens plate having the function of refracting image projection light in the horizontal direction. The Fresnel lens plate works to direct light emitted from the projector in the direction where the observer is. That is, it is used to brighten the screen.
On the other hand, a horizontal lenticular plate is used to spread light emitted from a projector in the left-right direction where an observer is located, that is, to widen an observation area and allow many people to observe. Also, to improve the contrast,
In general, black stripes are juxtaposed in a portion corresponding to a non-light-collecting portion of the lenticular lens plate on the back surface of the horizontal lenticular lens plate. In a conventional rear projection display including a Fresnel lens plate and a horizontal lenticular plate, the viewing angle is increased only in the horizontal direction, but the vertical viewing angle is not considered much. The viewing angle in the vertical direction is generally increased by using a diffusing agent to increase the viewing angle in the vertical direction, thereby expanding the observation area. Further, as another method, there is a means for increasing the viewing angle by using a vertical lenticular lens or the like having an action of refracting image projection light in the vertical direction. However, according to this method, when a wide viewing angle is obtained with a portable lenticular lens shape, the central brightness, that is, the screen gain becomes extremely low, resulting in a very dark screen.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in view of the above-mentioned circumstances. The purpose is to provide.

[0004]

SUMMARY OF THE INVENTION The present inventor has developed a conventional rear surface comprising a Fresnel lens sheet and a horizontal lenticular lens sheet having a group of cylindrical lenses arranged in a horizontal direction having a function of refracting image projection light in the horizontal direction. By using, as another optical article, a lens sheet in which a group of lenses having a composite shape having a cross-sectional shape in the vertical direction having an action of refracting image projection light in the vertical direction is used as a projection type screen, thereby providing a vertical visual field. The inventors have found that a bright rear-projection screen capable of widening the angle, having a wide horizontal viewing angle, and observing images in a wide range can be obtained, and arrived at the present invention.

That is, the invention according to claim 1 is a rear projection screen comprising a Fresnel lens sheet and a horizontal lenticular lens sheet in which a group of cylindrical lenses are arranged in a horizontal direction and has a function of refracting image projection light in the horizontal direction. A rear projection screen, wherein as another optical article, a lens sheet in which a lens group having a composite shape having a cross section in a vertical direction having an action of refracting image projection light in a vertical direction is used side by side is used. It is.

According to a second aspect of the present invention, in the rear projection screen according to the first aspect, the lens shape of the lens is a composite shape having a linear portion at each point formed by adjacent convex lens elements. It is characterized by.

According to a third aspect of the present invention, in the rear projection screen according to the first aspect, the lens shape is such that a curvature of the convex lens of the convex lens element of the lens sheet is provided at each apex formed by an adjacent convex lens element. It is characterized by comprising a composite shape having a concave lens element or a convex lens element having a radius of curvature larger than the radius.

According to a fourth aspect of the present invention, in the rear projection screen according to any one of the first to third aspects, the lens pitch of the lens sheet is 200 μm or less.

According to a fifth aspect of the present invention, in the rear projection screen according to any one of the first to fourth aspects, a flat surface opposite to the lens surface of the lens sheet and an opposite side to the lens surface of the Fresnel lens sheet. And the lens surface of the lens sheet is on the projection side,
A horizontal lenticular lens sheet is provided in combination.

According to a sixth aspect of the present invention, in the rear projection screen according to any one of the first to fourth aspects, the lens sheet is disposed between a Fresnel lens sheet and a lenticular lens sheet, and the lens surface is formed of a Fresnel lens. It is characterized in that a flat surface opposite to the lens surface is disposed on the lens sheet side so as to be on the lenticular lens sheet side.

<Operation> FIG. 1 shows a lens sheet in which a group of lenses having a composite shape in a vertical direction having a function of vertically refracting image projection light constituting a rear projection screen structure of the present invention are arranged side by side. FIG. (A)
Is a lens sheet 10 in which the lens cross-sectional shape of the lens sheet is a composite shape having a linear portion 12 at each point formed by adjacent convex lens elements 11. FIG.
FIG. 3 is a conceptual diagram showing light distribution characteristics of a lens sheet in a vertical direction. By adopting the composite shape as described above, it is possible to improve the brightness at the end of the visual field, that is, the brightness, as shown by the light distribution curve in FIG. If a lens sheet 40 having a simple lenticular shape 41 is used as shown in FIG. 2, the brightness decreases as shown by the light distribution curve (γ) in FIG. The ends are extremely dark compared to the lens sheet 10 having a composite shape having a straight portion 12 at each tip formed by the convex lens elements 11. In the rear projection display, it is actually necessary to provide a diffusion layer using a light diffusing agent serving to form an image on any of the optical articles constituting the screen. The two light-distribution curves at the end of the field of view, as indicated by the light distribution curve, have smoothed light distribution characteristics. The brightness at both ends of the visual field can be freely selected depending on the length and angle of the straight line portion formed at each apex formed by the adjacent convex lens elements. A display equipped with a rear-projection screen of the present invention using a lens sheet having a complex shape having a linear portion at each apex formed by adjacent convex lens elements is bright, can enlarge a vertical viewing angle, and has a horizontal viewing angle. You can observe a wide range of images with wide angles.

FIG. 1 shows a lens sheet in which a group of lenses having a composite shape in the vertical direction having a function of refracting the image projection light in the vertical direction and constituting the rear projection screen of the present invention are arranged side by side. As shown in b) and (c),
Each lens cross-sectional shape of the lens sheet is a composite shape having a concave lens element 22 or a convex lens element 32 having a radius of curvature larger than the radius of curvature of the convex lens of the convex lens element at each point formed by adjacent convex lens elements. Lens sheet 20 or 30. The observation state at the optimal position can be improved by giving the F-number a large curvature. By making the above-mentioned composite shape such that each tip formed by the adjacent convex lens element has a large F-number curvature, as can be seen from the light distribution curve of (β) in FIG. Can be improved, that is, the vertical viewing angle can be increased. The lens having a large radius of curvature provided at each point formed by adjacent convex lens elements may have a convex or concave surface. The brightness at both ends of the field of view of the light distribution characteristics can be freely selected by the curvature and angle of the lens provided at each point. Rear projection type of the present invention using a lens sheet having a composite shape having a concave lens element or a convex lens element having a radius of curvature larger than the radius of curvature of the convex lens of the convex lens element at each tip formed by adjacent convex lens elements. A display equipped with a screen is bright, can enlarge a vertical viewing angle, and can observe a wide range of images with a wide horizontal viewing angle.

[0013]

An embodiment of the present invention will be described in detail with reference to the drawings. The lens sheet in which a lens group having a compound shape having a cross-sectional shape in the vertical direction having an action of refracting image projection light in the vertical direction in the present invention shown in FIG. It is characterized in that it has a composite shape having a straight line portion at each point formed.

Further, the lens sheet according to the present invention, in which a lens group having a composite shape having a cross-sectional shape in the vertical direction having an action of refracting image projection light in the vertical direction is arranged side by side, the lens cross-sectional shape is determined by the adjacent convex lens element. It is characterized in that each formed point has a complex shape having a concave lens element or a convex lens element having a radius of curvature larger than the radius of curvature of the convex lens of the convex lens element.

The material and the manufacturing method of the lens sheet in which the lens groups having the composite shape in the vertical direction having the function of refracting the image projection light in the vertical direction in the present invention are juxtaposed are particularly limited. is not.

In the present invention, a lens sheet in which a lens group having a composite shape having a cross section in the vertical direction having a function of refracting image projection light in the vertical direction is arranged side by side has a lens pitch of 200 μm or less. .

FIG. 6 is a perspective view showing an example of the configuration of a conventional rear projection type screen having a two-sheet structure including a Fresnel lens plate and a horizontal lenticular plate. On the other hand, as shown in FIG. 4, the rear projection type screen according to the present invention has a lens in which a group of lenses having a composite shape in a vertical direction having an action of refracting image projection light in a vertical direction are arranged in parallel. The flat surface opposite to the lens surface of the sheet 1 and the flat surface opposite to the lens surface of the Fresnel lens sheet 50 are
For example, the lens sheet is adhered via an adhesive layer (not shown), and a horizontal lenticular lens sheet 60 provided with a stripe-shaped light-shielding layer 63 on the observation surface is provided so that the lens surface of the lens sheet is on the projection side. It is characterized by the following.

Further, the rear projection type screen of the present invention comprises:
As shown in FIG. 5, a lens sheet 1 in which a lens group having a complex sectional shape in the vertical direction having an action of refracting image projection light in the vertical direction is arranged side by side, and a Fresnel lens sheet 50 and a horizontal lenticular lens sheet 60 are used. The lens surface of the lens sheet 1 is on the Fresnel lens sheet side, and the flat surface opposite to the lens surface is on the horizontal lenticular lens sheet side provided with a stripe-shaped light shielding layer 63 on the observation surface. It is characterized in that it is arranged.

On the other hand, a conventional Fresnel screen constituting a rear projection type screen other than a lens sheet of the present invention other than a lens sheet in which a lens group having a composite shape in a vertical direction having a function of refracting image projection light in a vertical direction is juxtaposed. A lens sheet or a horizontal lenticular sheet is a method in which a sheet-shaped base material such as a polystyrene resin, an acrylic resin, a polycarbonate resin, or a vinyl chloride resin is heated, and pressed in a hot press in a hot melt state using a mold. Or, in a melt extrusion molding by an extruder, it can be manufactured by a known and commonly used method such as a method of embossing a sheet-like resin base material surface extruded in a molten state using an embossing roll mold, and is not particularly limited. Absent. In addition, as described above, only the lens portion can be formed on the light-transmitting substrate using an ultraviolet ray or an electron beam curable resin.

The method for providing the light-shielding layer on the outermost flat surface serving as the observation surface of the horizontal lenticular lens sheet is not particularly limited.
The following method is preferred in which a light-shielding layer is provided by making use of the fact that it becomes non-adhesive by being cured by irradiation of ultraviolet rays.
An ultraviolet curable resin layer is formed on a flat surface of the lenticular lens sheet opposite to the lens surface. Through each lenticular lens to the ultraviolet curable resin layer formed on the flat surface of the lenticular lens sheet from the lens side, irradiate vertically, and cure the resin of the portion focused by each lenticular lens After making the resin non-tacky, a light-shielding layer is formed by applying a black colorant only to the uncured portion of the adhesive resin. Alternatively, a black fine powder toner as a coloring agent can be selectively adhered only to uncured portions. Alternatively, using a transfer paper provided with a black ink layer, the black ink layer can be selectively adhered only to the uncured portion. According to the above-described exposure process, the lenticular lenses are collectively irradiated with parallel light from the lens side to the entire surface of the lenticular sheet. Therefore, the formed light-shielding layer is for a non-light-collecting portion due to the irradiation of the actual lenticular sheet with ultraviolet rays, and is surely provided at a place where the light-shielding layer must be formed, that is, at a region where image light does not pass. It can be formed with high positional accuracy.

[0021]

According to the present invention, it is possible to provide a bright rear-projection screen capable of widening the vertical viewing angle, widening the horizontal viewing angle, and observing images in a wide range.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a composite shape of a lens of a lens sheet according to the present invention.

FIG. 2 is a sectional view showing the shape of a conventional convex lens.

FIG. 3 is a conceptual diagram showing vertical light distribution characteristics of a lens sheet according to the present invention and a conventional convex lens sheet.

FIG. 4 is a perspective view showing an example of the configuration of a rear projection screen of the present invention.

FIG. 5 is a perspective view showing another example of the configuration of the rear projection screen of the present invention.

FIG. 6 is a perspective view showing an example of the configuration of a conventional rear projection screen.

[Explanation of symbols]

1, 10, 20, 30... A lens sheet 11 in which lens groups having a complex cross-sectional shape are arranged side by side 11, 21, 31,..., A convex lens element 12, a straight line provided at a point formed by an adjacent convex lens element Part 22: a concave lens element having a large radius of curvature provided at a point formed by an adjacent convex lens element 32: a convex lens element 40, 60 having a large radius of curvature provided at a point formed by an adjacent convex lens element Lenticular lens sheet 41 Lenticular lens shape 50 Fullerlens sheet 63 Light-blocking layer (black stripe) α: Vertical direction of the lens sheet provided with a straight line at the point formed by adjacent convex lens elements Light distribution curve β: concave lens element with a large radius of curvature at the tip formed by adjacent convex lens elements Light distribution curve in the vertical direction of the lenticular lens sheet vertical light distribution curve γ ...... convex lens sheet provided with a convex lens element is juxtaposed

Claims (6)

[Claims] 1. A rear projection type screen comprising a Fresnel lens sheet and a horizontal lenticular lens sheet having a group of cylindrical lenses arranged in a horizontal direction having a function of refracting image projection light in the horizontal direction. A rear projection screen using a lens sheet having a group of lenses having a composite shape in a vertical direction having a function of refracting image projection light in a vertical direction. 2. The rear projection screen according to claim 1, wherein the lens cross-sectional shape of the lens sheet is a composite shape having a linear portion at each point formed by adjacent convex lens elements. 3. A concave lens element or a convex lens element in which the lens cross-sectional shape of the lens sheet has a radius of curvature larger than the radius of curvature of the convex lens of the convex lens element of the lens sheet at each apex formed by adjacent convex lens elements. The rear projection type screen according to claim 1, wherein the rear projection type screen has a composite shape having the following. 4. The lens sheet according to claim 1, wherein a lens pitch of the lens sheet is 20.
The rear projection screen according to any one of claims 1 to 3, wherein the thickness is 0 µm or less. 5. A flat surface opposite to the lens surface of the lens sheet and a flat surface opposite to the lens surface of the Fresnel lens sheet are bonded together so that the lens surface of the lens sheet is on the projection side. The rear projection screen according to any one of claims 1 to 4, wherein the rear projection screen is provided in combination with a horizontal lenticular lens sheet. 6. The lens sheet is disposed between a Fresnel lens sheet and a lenticular lens sheet, and the lens surface of the lens sheet faces the Fresnel lens sheet.
The rear projection screen according to any one of claims 1 to 4, wherein the flat surface opposite to the lens surface is disposed on the horizontal lenticular lens sheet side.