JPH08227106A - Back projection type screen - Google Patents

Abstract

PURPOSE: To easily produce a back projection type screen even for a large screen and to realize variation in optical design by combining and using two linear Fresnel lens sheets so that their Fresnel lens trains may cross each other. CONSTITUTION: As for the linear Fresnel lens sheet and a lenticular lens in this back projection type screen; two linear Fresnel lens sheets 2 and 3 are combined so that their Fresnel lens trains may cross each other and arranged on a light source side, then the lenticular lens sheet 1 is arranged on an observation side. A linear Fresnel lens sheet whose Fresnel lens train is in the same direction as the lens train of the lenticular lens sheet 1 is used as the linear Fresnel lens sheet 3 arranged on the light source side. A linear Fresnel lens sheet whose Fresnel lens train is orthogonal to the lens train of the lenticular lens sheet 1 is used as the linear Fresnel lens sheet 2. Thus, a moire phenomenon is restrained.

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 used as a screen for a projection television, a microfilm reader, etc. More specifically, it can be easily manufactured on a large screen and can be used for various optical systems. The present invention relates to a rear projection type screen that can take design variations.

[0002]

2. Description of the Related Art A rear projection type screen used in a projection television or the like produces a bright image to some extent even when viewed from an oblique direction so that the brightness and uniformity of the screen can be obtained by diffusing the projected light. For observation, a Fresnel lens sheet is arranged on the light source side and a lenticular lens sheet is arranged on the observation side. The Fresnel lens sheet directs the light rays incident from the light source toward the observer so that the four corners of the screen are not darkened. Also, the lenticular lens sheet is
The three colors of red, green, and blue (RGB) incident from a three-tube type projector are mixed to provide color uniformity, and light rays are diffused in the horizontal direction to widen the horizontal viewing angle. Such Fresnel lens sheets and lenticular lens sheets are made of synthetic resin such as (meth) acrylic resin, polycarbonate resin and vinyl chloride resin, and are extruded, casted, injection molded, cut, heat pressed or It is manufactured by a method using an active energy ray-curable resin.

[0003]

In recent years, due to the development of projection televisions and other projection devices, the use of large projection televisions in various fields such as exhibitions has increased, and large rear projections of 100 inches or more have been projected. The demand for mold screens tends to increase. However, it was difficult to mass-produce a large screen of 100 inches or more by the above method. In particular, as the Fresnel lens sheet, a circular Fresnel lens in which a large number of concentric lens units are formed is used, and there is a limit to the size that can be manufactured, and a large circular Fresnel lens sheet exceeding 100 inches is used. Was difficult to manufacture easily.

Further, in the circular Fresnel lens sheet, the focal lengths in the vertical direction and the horizontal direction cannot be changed, and there is a limit in variation in optical design.
For example, with the downsizing of projection televisions, it has been required to shorten the projection distance of the light source. When the projection distance of the light source is shortened, the incidence of light rays at the peripheral portion of the Fresnel lens sheet, particularly the peripheral portion in the horizontal direction which is the longitudinal direction becomes a steep angle, and total reflection easily occurs,
If the inclination angle of the Fresnel lens in the peripheral portion is made gentle to prevent this, the focal length of the Fresnel lens sheet in the vertical direction and the horizontal direction also becomes long. But,
The directivity (diffusivity) in the vertical direction is extremely narrower than that in the horizontal direction, and as the focal length in the vertical direction becomes longer, phenomena such as hot band and see-through become noticeable. In such a case, if an optical design capable of changing the focal lengths in the horizontal direction and the vertical direction can be performed, such a problem can be easily solved, but the circular Fresnel lens sheet cannot deal with it.
Therefore, an object of the present invention is to provide a rear projection type screen which can be easily manufactured even in a large screen and can have various optical design variations.

[0005]

The inventors of the present invention have arrived at the present invention as a result of earnest studies on the structure of a Fresnel lens sheet in view of the above problems of the prior art. That is, the rear projection type screen of the present invention is disposed on the light source side and the Fresnel lens sheet in which two linear Fresnel lens sheets are combined so that both Fresnel lens rows intersect each other, and the rear projection type screen is disposed on the observation side. It is characterized by being composed of a lenticular lens sheet.

As shown in FIG. 1, the rear projection type screen of the present invention comprises two linear Fresnel lens sheets 2,
The Fresnel lens sheet in which 3 is combined so that the Fresnel lens rows intersect each other is arranged on the light source side, and
It is configured by arranging the lenticular lens sheet 1 on the observation side. The linear Fresnel lens sheet of the present invention is made of a resin having good light transmittance such as an acrylic resin, a polycarbonate resin, an olefin resin, a styrene resin, a vinyl chloride resin, or a mixed resin thereof, and is cast-molded. Method, injection molding method, hot press molding method, extrusion molding method, cutting method, or method using an active energy ray-curable resin. In particular, even in a Fresnel lens sheet used for a large screen of 100 inches or more, since it has a linear Fresnel lens shape which is a simple pattern compared to a circular Fresnel lens, it is possible to use a method such as an extrusion molding method or a cutting method. , Can be easily manufactured up to large size. The thickness of the linear Fresnel lens sheet is not particularly limited, but is preferably thin from the viewpoint of reducing multiple images due to flare light due to interface reflection.

As shown in FIG. 2, the linear Fresnel lens formed on the linear Fresnel lens sheet is formed by arranging a large number of linear Fresnel lens rows 4 in parallel to form one Fresnel center 5. Is. The Fresnel center 5 formed on the linear Fresnel lens sheet is normally formed at the center of the linear Fresnel lens sheet, but the position is shifted for the purpose of adjusting the installation position of the device or the condensing position depending on the observation place. It can also be formed eccentrically. In addition, the linear Fresnel lens sheet of the present invention is formed by joining or adhering a plurality of linear Fresnel lens sheets as shown in FIG. Good. in this case,
Bonding with the same direction as the Fresnel lens row direction as the cemented surface can minimize the width of the cemented part, and solvent etc. may flow along the lens groove and contaminate the lens part near the cemented part. None preferred. When it is necessary to join the Fresnel lens in the direction orthogonal to the column direction as the joining surface, join with a solvent in a state where a sealing agent such as a silicone resin has been sealed in the vicinity of the joint in advance, and then the solvent etc. It is necessary to prevent the contamination of the lens portion near the joint portion due to the inflow into the lens groove. Also in this case, the alignment of the lenses of the linear Fresnel lens sheets to be joined can be performed more easily than when the circular Fresnel lens sheets are joined together.

Lenticular lens sheet 1 of the present invention
Is composed of a synthetic resin having a high light transmittance such as an acrylic resin, a polycarbonate resin, an olefin resin, a styrene resin, a vinyl chloride resin or a mixed resin thereof, and an extrusion molding method, a casting molding method, It is manufactured by a commonly used method such as an injection molding method, a hot press molding method, a cutting method or an active energy ray curing method. The lens shape of the lenticular lens formed on the lenticular lens sheet 1 is not particularly limited, and a generally used lenticular lens having a semicircular cross section, a semielliptical cross section, or the like can be used. Also, as the lenticular lens sheet 1,
A single-sided lenticular lens sheet with a lenticular lens formed on either the exit surface or the entrance surface,
A double-sided lenticular lens sheet having lenticular lenses formed on both the exit surface and the entrance surface can be used. Further, on the observation side surface of the lenticular lens sheet 1, a black stripe may be formed on the light opaque portion of the lenticular lens for the purpose of improving the contrast of an image.

In the present invention, the lenticular lens sheet 1 or the linear Fresnel lens sheets 2 and 3 are used for the purpose of widening the viewing angle in the vertical direction and suppressing the occurrence of moire phenomenon and the reflection of the Fresnel lens and the lenticular lens. A small amount of the light diffusing agent may be mixed in at least one of them in the range of 0.1 to 3% by weight. The light diffusing agent is not particularly limited, and known diffusing agents can be used, for example, silica, calcium carbonate, barium sulfate, titanium oxide, alumina, zinc oxide, inorganic fine particles such as crows, crosslinked polymers and the like. Examples include organic fine particles. Further, instead of or in combination with the light diffusing agent, a light diffusing agent layer containing the light diffusing agent may be formed, or a horizontal micro-lenticular lens surface or fine uneven surface may be formed. You may. Further, in addition to the light diffusing agent, additives such as a tinting agent, a wavelength-specific absorber, a flame retardant, a light stabilizer, and a heat deterioration preventing agent can be added as required.

The rear projection type screen of the present invention comprises a linear Fresnel lens sheet and a lenticular lens sheet as described above, and two linear Fresnel lens sheets 2 and 3 as shown in FIG. Are arranged on the light source side so as to intersect with each other, and the lenticular lens sheet 1 is arranged on the observation side. The arrangement of the two linear Fresnel lens sheets 2 and 3 is not particularly limited, but as the linear Fresnel lens sheet 3 arranged on the light source side, the Fresnel lens row has the same direction as the lens row of the lenticular lens sheet 1. As a linear Fresnel lens sheet 2 to be arranged on the side of the lenticular lens sheet 1, a vertical Fresnel lens sheet (vertical direction linear Fresnel lens sheet) is used. Fresnel lens sheet)
It is preferable to use the above because it is possible to suppress the moire phenomenon caused by the Fresnel lens and the lenticular lens.

Further, in the rear projection type screen of the present invention, since the inclination angle, shape, pitch, etc. of each Fresnel lens of the two linear Fresnel lens sheets can be set independently, the horizontal and vertical directions It is possible to give anisotropy to the focal length in the direction, and various optical designs can be easily performed. For example, as to the phenomenon such as hot band and see-through which occurs when the projection distance of the light source is shortened, as shown in FIG. 4, only the vertical linear Fresnel lens sheet is used without changing the vertical focal length. By making the inclination angle of the Fresnel lens gentle, the total reflection at the peripheral portion can be prevented without making phenomena such as hot band and see-through remarkable.
Also, not only when the projection distance of the light source is short, but when a phenomenon such as a hot band or see-through is remarkable, the tilt angle of the Fresnel lens of the lateral linear Fresnel lens sheet is adjusted to adjust the focal length only in the vertical direction. By shortening, it is possible to reduce phenomena such as hot bands and see-through without impairing the image characteristics in the horizontal direction.

[0012]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 A linear Fresnel lens having a focal length of 1000 mm and a pitch of 0.5 mm and a Fresnel center at the center was formed 3
Two 048 mm × 2286 mm polycarbonate resin linear Fresnel lens sheets were prepared. On the other hand, a lenticular lens with a pitch of 0.7 mm was formed 304
A double-sided lenticular lens sheet made of 8 mm × 2286 mm polycarbonate resin was prepared.

The two linear Fresnel lens sheets and the lenticular lens sheet thus obtained are arranged in this order from the light source side to the vertical linear Fresnel lens sheet, the horizontal linear Fresnel lens sheet, and the lenticular lens sheet, and rear projection is performed. I made a mold screen. A 150-inch rear projection type screen device was assembled using this rear projection type screen. When an image was projected using this rear projection type screen device, there was no moire phenomenon, and an image with excellent uniform brightness was obtained.

Example 2 Two 1016 mm × 2286 mm acrylic resin linear Fresnel lens sheets each having a focal length of 1000 mm and a pitch of 0.3 mm and a linear Fresnel lens having a Fresnel center 5 in the center, and a focal length of 1000 mm and a pitch of 0. Four linear Fresnel lens sheets of 1016 mm × 2286 mm made of acrylic resin were prepared, each having a linear Fresnel lens of 0.3 mm and having linear Fresnel lenses formed on the left and right of the linear Fresnel lens sheet having the Fresnel center 5 to form a continuous linear Fresnel lens. . The six obtained linear Fresnel lens sheets were joined by solvent adhesion to prepare two 3048 mm × 2286 mm linear Fresnel lens sheets.

On the other hand, three double-sided lenticular lens sheets of 1016 mm × 2286 mm made of polycarbonate having lenticular lenses with a pitch of 0.42 mm were prepared. 3048 mm x 3 pieces of the obtained double-sided lenticular lens sheet are joined by solvent adhesion.
A 2286 mm double-sided lenticular lens sheet was prepared. The two linear Fresnel lens sheets and the lenticular lens sheet thus obtained are arranged in this order from the light source side to the longitudinal linear Fresnel lens sheet, the lateral linear Fresnel lens sheet, and the lenticular lens sheet to form a rear projection screen. Created. A 150-inch rear projection type screen device was assembled using this rear projection type screen. When an image was projected using this rear projection type screen device, an excellent image was obtained in which the joint portion of the linear Fresnel lens sheet was not conspicuous and there was no moire phenomenon and the entire screen was uniform and bright.

Example 3 A longitudinal linear Fresnel lens sheet made of a polycarbonate resin of 3048 mm × 2286 mm having a focal length of 1000 mm, a pitch of 0.5 mm, and a linear Fresnel lens having a Fresnel center 5 at the center was formed. A lateral linear Fresnel lens sheet made of a polycarbonate resin having a focal length of 700 mm, a pitch of 0.5 mm, and a linear Fresnel lens having a Fresnel center 5 in the center was formed and having a size of 3048 mm × 2286 mm. On the other hand, a 3048 mm × 2286 mm acrylic resin double-sided lenticular lens sheet having lenticular lenses with a pitch of 0.7 mm was formed.

The vertical and horizontal linear Fresnel lens sheets and the lenticular lens sheet thus obtained are arranged in this order from the light source side to the vertical linear Fresnel lens sheet, the horizontal linear Fresnel lens sheet, and the lenticular lens sheet. Then, the rear projection type screen was created. With this rear projection type screen,
An inch rear projection type multi-screen device was assembled.
When an image was projected using this rear projection type multi-screen device, an excellent image without a moire phenomenon, the entire screen was uniform and bright, and a hot band phenomenon was not obtained was obtained.

[0018]

The rear projection type screen of the present invention can be easily manufactured even in a large screen by using two linear Fresnel lens sheets in combination so that both Fresnel lens rows intersect each other. Can
It was possible to make various optical design variations possible.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outline of a configuration of a rear projection type screen of the present invention.

FIG. 2 is a sectional view showing an outline of a linear Fresnel lens sheet of the present invention.

FIG. 3 is a sectional view showing an outline of a cemented linear Fresnel lens sheet of the present invention.

FIG. 4 is a schematic diagram showing optical characteristics of a rear projection type screen of the present invention.

[Explanation of symbols]

 1 Lenticular Lens Sheet 2 Horizontal Linear Fresnel Lens Sheet 3 Vertical Linear Fresnel Lens Sheet 4 Fresnel Lens Row 5 Fresnel Center 6 Joint

Claims (2)

[Claims] 1. A Fresnel lens sheet arranged on the light source side, in which two linear Fresnel lens sheets are combined so that both Fresnel lens rows intersect with each other, and a lenticular lens sheet arranged on the observation side. A rear projection type screen characterized in that 2. The rear projection screen according to claim 1, wherein the vertical focal length and the horizontal focal length are different.