JPH05100317A - Multi-surface fresnel lens sheet - Google Patents

Abstract

PURPOSE:To eliminate the disturbance to a picture and to increase strength by bonding the backs of plural Fresnel lens sheets with one transparent substrate. CONSTITUTION:The multi-surface Fresnel lens sheet 10A is formed by bonding the backs of Fresnel lens sheet 11 and 12 to one transparent substrate 13 with an adhesive layer 14. Since the backs of the Fresnel lens sheets 11 and 12 are respectively bonded to the transparent substrate 13, the bonding part does not appear on a screen and the picture is not disturbed. Meanwhile, since the entire backs of the sheets 11 and 12 are bonded to the transparent substrate 13, the strength is increased. Furthermore, the adhesive layer 14 is uniformly formed free of bubbles, etc., by allowing one among the sheets 11 and 12 and the substrate 13 to be a thin film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multifaceted Fresnel lens sheet obtained by joining a plurality of Fresnel lens sheets.

[0002]

2. Description of the Related Art In recent years, a large-sized image display device has been demanded, and a projection image system for enlarging and projecting an image on a screen for observation is expected as a system which can easily obtain a large image of 100 inches or more. There is.
Among such projection image systems, the transmission type projection system for observing the projected image through the transmission type screen has a high contrast.
Images with good visibility can be obtained. In such a transmissive screen, a lens sheet in which a large number of fine lenses are arranged with high precision is indispensable, and it is necessary to use a Fresnel lens sheet as a field lens for making the brightness of the entire screen uniform.

Since many Fresnel lens sheets must be formed with high precision and a large number of fine lenses, a synthetic resin having a high light-transmitting property such as acrylic resin is produced by thermoforming, casting or the like using a mold. Has been done. In this case, it is not practical to manufacture a large screen of 100 to 200 inches or more because it is technically difficult and costly to manufacture it by using a mold with high precision.

In order to solve such a problem, there is a multi-image system in which a plurality of projection systems are arranged to form a large image. In this system, the uniformity of the screen is very important, and the Fresnel lens sheet is indispensable as a constituent element of the transmissive screen. Therefore, the screen of this image system requires a multi-sided Fresnel lens sheet in which a plurality of Fresnel lens sheets are arranged and joined.

Conventionally, as a method of joining a large number of Fresnel lens sheets, a grid-like frame is made of synthetic resin,
There were a method of putting a Fresnel lens sheet in the frame, a method of fixing the Fresnel lens sheet to a transparent substrate with a metal screw, and a method of adhering the Fresnel lens sheet at the end portions.

[0006]

However, in the above method, in order to hold the lens sheet by the frame, the frame itself must have strength. Also, when the lens sheet expands or contracts due to environmental changes such as temperature and humidity,
In order to prevent the lens sheet from coming off the frame, the frame must have a certain width, and the width cannot be less than several mm. However, there is a problem that the image quality is deteriorated.

[0007] In the above method, the screws impair the image quality and it is necessary to provide a gap between the Fresnel lens sheets in order to absorb the expansion and contraction of the Fresnel lens sheets. Different parts of about 10 mm are formed.

In the above method, since the adhesive layer needs to have a certain thickness (usually about 0.5 mm), that portion will have portions having different optical characteristics. Further, the thickness of the Fresnel lens sheet is as thin as about 2 to 10 mm in practical use, and the Fresnel lens surface is slightly rusty, so that the adhesive easily penetrates into the lens surface due to capillary development, and the end surfaces face each other. It is difficult to bond.

In the large screen of Japanese Patent Laid-Open No. 58-168042, a structure is disclosed in which a lenticular lens sheet is butted and adhered, and a backing plate is adhered to the other surface. This is a Fresnel lens. When applied to a sheet, as in the case of the above-mentioned method, the adhesive layer needs to have a certain thickness, and the disadvantage that the adhesive penetrates the lens surface cannot be avoided.

The present invention is intended to solve such a drawback, and an object thereof is to provide a multi-sided Fresnel lens sheet which is free from deterioration of image quality and is strong.

[0011]

In order to solve the above-mentioned problems, the multifaceted Fresnel lens sheet according to the present invention is formed by bonding a plurality of Fresnel lens sheets to another transparent substrate on the rear surface of the Fresnel lens surface and integrating them. There is a configuration.

In this case, each Fresnel lens sheet may be in the form of a thin film. The transparent substrate may be in the form of a thin film.

An optical element for diffusing light may be formed on the light entrance surface of the transparent substrate.

[0014]

According to the above construction, since a plurality of Fresnel lens sheets are bonded to the transparent substrate on the back surface, respectively, the bonded portions are not visible on the screen and there is no image interference. Moreover, since the entire back surface of the Fresnel lens sheet is bonded to the transparent substrate, the strength can be increased.

Furthermore, by forming one of the Fresnel lens sheet and the transparent substrate into a thin film, the adhesive layer can be formed uniformly without unevenness and bubbles.

[0016]

The present invention will be described in detail below with reference to the drawings and the like with reference to the drawings. FIG. 1 is a perspective view schematically showing a first embodiment of a multifaceted Fresnel lens sheet according to the present invention. Multi-sided Fresnel lens sheet 10A
Is a transparent substrate 13 on the back side of the Fresnel lens sheets 11 and 12 joined by an adhesive layer 14.

The Fresnel lens sheets 11 and 12 each have a length and width of 600 mm × 800 mm and a thickness of 3 mm.
And is molded by a method such as thermoforming, casting, or photopolymer molding using a resin such as methacrylic resin or polycarbonate. Since the Fresnel lens sheets 11 and 12 have flat back surfaces (light entrance surfaces), this portion can be bonded to the transparent substrate 13 by the adhesive layer 14.

The transparent substrate 13 is made of a highly transparent resin such as acrylic and has a thickness of 3 mm.
The adhesive layer 14 is formed by adhering or adhering with an adhesive or the like, and the adhesive is the Fresnel lens sheet 1
It is preferable to use a pressure-sensitive adhesive of the same series as that of the transparent substrate 13 and the transparent substrate 13, and for example, an acrylic or epoxy transparent adhesive can be used.

2 and 3 are perspective views schematically showing second and third embodiments of the multifaceted Fresnel lens sheet according to the present invention. In addition, the same reference numerals are given to the portions having the same functions as those in the first embodiment. The multifaceted Fresnel lens sheet 10B of the second embodiment is different from the first embodiment in that the Fresnel lens sheets 11B and 12B are in the form of transparent films having a thickness of 0.2 mm. The multi-sided Fresnel lens sheet 10C of the third embodiment differs from the first embodiment in that the transparent substrate 13C is a transparent film having a thickness of 0.2 mm.

As in the second and third embodiments, when either the Fresnel lens sheets 11B, 12B or the transparent substrate 13C is in the form of a thin film, the adhesive layer 14 has no unevenness or bubbles. There is an advantage that it can be easily formed. For example, when the Fresnel lens sheets 11B and 12B are in the form of thin films, the thin film lens sheet is placed on the transparent substrate 13 to which a transparent adhesive or pressure sensitive adhesive 14 has been applied in advance as shown in FIG. By stacking, pressing the roll 20 or the like from above to expel air bubbles and making the adhesive layer uniform, a good multifaceted Fresnel lens sheet free from air bubbles, unevenness, etc. can be obtained. Also,
As shown in FIG. 5, by masking the adhesive layers of the Fresnel lens sheets 11B and 12B with a masking tape 21 such as an adhesive tape, the adhesive does not stick out from the joint portion, and the multifaceted Fresnel lens sheet can be easily formed. Can be manufactured.

When the Fresnel lens sheets 11B and 12B are used as components of a projection screen, a horizontal lenticular lens 13L for spreading light vertically to the light entrance side of the Fresnel lens is used in order to widen the vertical viewing angle of the screen. Forming is done. Also in the present invention, by forming the horizontal lenticular lens 13L in advance on the light incident side of the transparent substrate, a similar one can be easily formed as shown in FIG.

When an element for diffusing light is formed on the light incident side of the Fresnel lens sheet as described above, the resolution of the image projected on the screen decreases as the thickness of the Fresnel lens sheet increases. There is a problem,
It is not preferable to increase the thickness of the Fresnel lens sheet. If the Fresnel lens sheet is too thin, it will be difficult to hold it. The appropriate thickness of the multifaceted Fresnel lens sheet in which the horizontal lenticular lens is formed on the light-incident side varies depending on the size of the sheet, but is preferably about 2 to 5 mm. In the present invention, by forming either the Fresnel lens sheet or the transparent substrate into a thin film, a polyhedral Fresnel lens sheet having an appropriate thickness can be easily produced.

[0023]

As described in detail above, according to the present invention, since a plurality of Fresnel lens sheets are respectively joined to the transparent substrate on the back surface, there is no image interference and
A multifaceted Fresnel lens sheet having high strength can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a first embodiment of a multifaceted Fresnel lens sheet according to the present invention.

FIG. 2 is a perspective view schematically showing a second embodiment (when the Fresnel lens sheet is a thin film) of the multifaceted Fresnel lens sheet according to the present invention.

FIG. 3 is a perspective view schematically showing a third embodiment (when the transparent substrate is a thin film) of the multifaceted Fresnel lens sheet according to the present invention.

FIG. 4 is a perspective view showing a method of manufacturing a multifaceted Fresnel lens sheet according to a second example.

FIG. 5 is a perspective view showing another manufacturing method of the multifaceted Fresnel lens sheet according to the second embodiment.

FIG. 6 is a perspective view schematically showing a fourth embodiment of the multifaceted Fresnel lens sheet according to the present invention.

[Explanation of symbols]

 10A, 10B, 10C Polyhedral Fresnel lens sheet 11, 12 Fresnel lens sheet 13 Transparent substrate 14 Adhesive layer

Claims (4)

[Claims] 1. A multi-sided Fresnel lens sheet, characterized in that a plurality of Fresnel lens sheets are joined and integrated with another transparent substrate on the back side of the Fresnel lens surface. 2. The multifaceted Fresnel lens sheet according to claim 1, wherein each of the Fresnel lens sheets has a thin film shape. 3. The multi-sided Fresnel lens sheet according to claim 1, wherein the transparent substrate has a thin film shape. 4. An optical element for diffusing light is formed on a light entrance surface of the transparent substrate.
The multifaceted Fresnel lens sheet according to any one of items 1 to 3.