JPH09230508A - Rear projection type screen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rear projection type screen constituted so that the resolution is high and the visual field range is wide. SOLUTION: This screen is constituted of a circular Fresnel lens sheet 2 arranged on the light source side and a lenticular lens sheet 1 arranged on the observation side. Then, the sheet 1 is constituted so that many lenticular lenses 3 are formed in parallel on the observation surface side thereof and many prism columns 11 are formed in parallel on the incident surface side thereof in an identical direction to the lenses 3.

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 of a projection television, a microfilm reader or the like, and more particularly to a rear projection type screen having a wide viewing angle and high resolution. It is a thing.

[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. As such a lenticular lens sheet, a double-sided lenticular lens sheet having lens shapes on both the entrance surface and the exit surface,
A single-sided lenticular lens sheet with a lens shape on one of the entrance surface or the exit surface is used, and a synthetic resin such as (meth) acrylic resin, polycarbonate resin, or vinyl chloride resin is used for extrusion molding, It is manufactured by a casting method, an injection molding method, a hot press molding method or a method using an active energy ray-curable resin.

[0003]

In recent years, high resolution broadcasting systems such as clear vision and high vision have been achieved.
Also, engineering workstations, CAD,
A screen having a high resolution has been used as a screen of CAM or the like. Furthermore, in correspondence with higher resolution, XGA, S
-Liquid crystal projectors such as XGA have been adopted. In order to cope with such high resolution and to reduce the moire phenomenon that occurs between liquid crystal pixels, a rear projection type screen having a very fine pitch lenticular lens is required. .

However, in the double-sided lenticular lens sheet, it is necessary to reduce the thickness of the sheet in terms of optical performance as the lenticular lens becomes finer in pitch, and the pitch of about 0.5 mm is also limited in terms of the molding method. Met. Further, the single-sided lenticular lens sheet can have a finer pitch than the double-sided lenticular lens sheet, but the combined shape of the lenticular lenses is complicated, so the pitch is about 0.4 mm. In particular, when using a liquid crystal projector, it is necessary to make the pitch finer, and it has been difficult to manufacture a single-sided lenticular lens sheet having sufficient optical characteristics.

On the other hand, in a lenticular lens sheet formed with a lenticular lens having a relatively simple shape such as a spherical shape or an aspherical shape, it is possible to make a fine pitch relatively in terms of shape, but an ordinary acrylic resin is used. In this case, the viewing angle is about 50 due to the limitation of the critical angle.
It has a problem that it can be expanded only up to a degree, and that it can be observed only from the vicinity of the front. Therefore, an object of the present invention is to provide a rear projection type screen that can cope with a fine pitch of a lenticular lens, has a wide viewing angle, and high resolution.

[0006]

The inventors of the present invention have arrived at the present invention as a result of earnestly examining the structure of a rear projection type screen in view of the problems of the above-mentioned prior art. That is, the rear projection screen of the present invention is composed of a circular Fresnel lens sheet arranged on the light source side and a lenticular lens sheet arranged on the observation side, and the lenticular lens sheet has a large number of lenticular lenses on the observation surface side. The lens is formed in parallel, and a large number of prism rows are formed in parallel in the same direction as the lenticular lens on the incident surface side.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The rear projection type screen of the present invention is constructed by arranging a lenticular lens sheet 1 on the observation side and a circular Fresnel lens sheet 2 on the light source side as shown in FIG. It is a thing. In this lenticular lens sheet 1, a large number of fine pitch lenticular lenses 3 having a spherical or aspherical lens shape are formed in parallel in the vertical direction on the observation surface side, and the lenticular lens 3 and the lenticular lens 3 are formed on the incident surface side. A large number of prism rows 4 are formed in parallel in the same direction.

Thus, the lenticular lens sheet 1
By forming the prism rows 4 on the incident surface side, the light rays incident on the prism rows 4 obliquely enter the lenticular lens 3 from both left and right directions, as shown in FIG. Therefore, the characteristics of the light emitted from the lenticular lens sheet 1 are two types in which the peak of the gain as shown by the solid line and the dotted line in FIG. The output light characteristics are combined, and the output light characteristics are such that the outermost viewing angles on both sides are widened as shown in FIG. Therefore, a wide viewing angle is ensured even when the lenticular lens 3 having a high resolution and a very fine pitch is formed by using a relatively simple lens shape having a narrow viewing angle originally. It becomes possible.

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 or an active energy ray curing method.

The lens shape of the lenticular lens 3 formed on the lenticular lens sheet 1 is not particularly limited, and the shape of a generally used lenticular lens having a semicircular or semielliptical cross section is used. Can be used, but a relatively simple shape capable of coping with a fine pitch is particularly preferable. The pitch of the lenticular lens 3 is appropriately set according to the purpose of use, but is 0.4 from the viewpoint of increasing the image resolution.
The pitch is preferably less than or equal to mm.

The shape of the prism array 4 formed on the lenticular lens sheet 1 is not particularly limited and various shapes can be used, but the prism array having an isosceles triangular cross section is particularly preferable. If necessary, as shown in FIGS. 5 and 6, the flat portions 5 may be formed between the prism rows, or the flat portions 6 may be formed at the tops of the prism rows. In particular, FIG. 5 and FIG.
By forming the flat parts 5 and 6 like
It is possible to suppress a decrease in brightness near the front. The ratio of the flat portions 5 and 6 can be appropriately set according to the required characteristics.

The apex angle of the prism array 4 is selected by the refractive index of the lenticular lens sheet 1 and the like, and is generally 30.
The angle of incidence of the light beam on the lenticular lens 3 is preferably set in the range of 3 to 20 degrees, although it is set in the range of about 150 degrees. This is because when the angle of incidence of the light ray on the lenticular lens 3 exceeds 20 degrees, the brightness in the vicinity of the front tends to decrease, and conversely, when it is less than 3 degrees, a sufficient viewing angle tends to not be obtained. This is because. In addition, the pitch of the prism rows 4 suppresses the moire phenomenon that occurs between the prism rows 4 and the lenticular lens 3 and the deterioration of the optical characteristics due to the positional relationship between the central axis of the lenticular lenses 3 and the central axis of the prism rows 4. It is preferably 1/3 or less of the pitch of 3 and more preferably 1/5 or less.

The circular Fresnel lens sheet 2 of the present invention is made of a 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. It can be easily manufactured by a commonly used method such as a casting method, an injection molding method, a hot press molding method, an extrusion molding method, or a method using an active energy ray-curable resin. Further, the thickness of the circular Fresnel lens sheet 2 is not particularly limited, but it is preferably thin from the viewpoint of reducing multiple images due to flare light due to interface reflection and improving resolution.

In the present invention, at least the lenticular lens sheet 1 or the circular Fresnel lens sheet 2 is used for the purpose of widening the viewing angle in the vertical direction and suppressing the occurrence or reflection of the moire phenomenon due to the circular Fresnel lens and the lenticular lens. On the other hand, 0.
A small amount of the light diffusing agent may be mixed in the range of about 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.
Furthermore, in addition to light diffusing agents, tint agents, wavelength-specific absorbers,
Additives such as flame retardants, light stabilizers, and heat deterioration inhibitors can be added as necessary.

[0015]

The present invention will be specifically described below with reference to examples. Example 1 A large number of lenticular lenses having a pitch of 0.3 mm and a radius of curvature of 0.5 mm were formed in parallel on the observation surface side of a 3 mm thick acrylic resin plate mixed with a diffusing agent and a tinting agent by hot press molding, and then incident. 0.05m pitch on the surface side
A large number of prism rows with m and an apex angle of 95 degrees were formed in parallel in the same direction as the lenticular lens to obtain a lenticular lens sheet. On the other hand, a transparent acrylic resin plate having a thickness of 3 mm was formed on one surface by heating and press molding with a pitch of 0.
A circular Fresnel lens of 5 mm was formed to obtain a circular Fresnel lens sheet.

The obtained lenticular lens sheet is
The rear projection type screen was constructed by arranging the lenticular lens surface on the observation side so that the surface becomes the emission surface, and disposing the circular Fresnel lens sheet on the light source side so that the circular Fresnel lens surface became the emission surface. When this rear projection type screen is attached to a 50-inch projection television and the image is observed, an excellent image with a high resolution and a sense of depth is obtained, and the image is also observed within a visual range of ± 80 degrees or more. And had a sufficiently wide field of view.

Example 2 A large number of lenticular lenses having a pitch of 0.3 mm and a radius of curvature of 0.5 mm are formed in parallel on the observation surface side of a 3 mm thick acrylic resin plate mixed with a diffusing agent and a tinting agent by hot press molding. And the pitch is 0.05m on the incident surface side.
A large number of prism rows with m and an apex angle of 95 degrees were formed in the same direction as the lenticular lens in parallel with a 0.005 mm flat portion alternately in parallel to obtain a lenticular lens sheet.
On the other hand, a circular Fresnel lens sheet having a pitch of 0.5 mm was formed on one surface of a transparent acrylic resin plate having a thickness of 3 mm by hot press molding to obtain a circular Fresnel lens sheet.

The obtained lenticular lens sheet is
The rear projection type screen was constructed by arranging the lenticular lens surface on the observation side so that the surface becomes the emission surface, and disposing the circular Fresnel lens sheet on the light source side so that the circular Fresnel lens surface became the emission surface. When this rear projection type screen was attached to a 50-inch projection TV and the images were observed, excellent images with high resolution and a sense of depth were obtained, and there was little reduction in brightness near the front, ± 80 degrees or more. The image could be observed even in the visual field range, and the visual field range was sufficiently wide.

Comparative Example 1 An acrylic resin plate having a thickness of 3 mm mixed with a diffusing agent and a tinting agent was formed by heating and press forming a number of lenticular lenses having a pitch of 0.2 mm and a radius of curvature of 0.5 mm in parallel on one surface. Then, a lenticular lens sheet was obtained. On the other hand, a transparent acrylic resin plate with a thickness of 3 mm
Pitch 0.5m on one surface by hot press molding
A circular Fresnel lens of m was formed to obtain a circular Fresnel lens sheet.

The obtained lenticular lens sheet is
A rear projection type screen was prepared by arranging the lenticular lens surface on the observation side so that the incident surface and the circular Fresnel lens sheet were arranged on the light source side so that the circular Fresnel lens surface became the emitting surface. When this rear projection type screen was attached to a 50-inch projection TV and the image was observed, the field of view range was ± 50.
The image was uneven, with a fairly narrow degree, and only the front area was bright.

[0021]

The present invention uses a lenticular lens sheet in which a large number of fine-pitch lenticular lenses are formed in parallel on the observation surface side and a large number of prism rows are formed in parallel in the same direction as the lenticular lenses on the incident surface side. Thus, a rear projection type screen having a high resolution and a wide field of view can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the outline of the configuration of a rear projection type screen of the present invention.

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

FIG. 3 is an explanatory diagram of outgoing light characteristics of the present invention.

FIG. 4 is a schematic diagram showing emission light characteristics of the present invention.

FIG. 5 is a sectional view showing an outline of a lenticular lens sheet of the present invention.

FIG. 6 is a sectional view showing an outline of a lenticular lens sheet of the present invention.

[Explanation of symbols]

 1 Lenticular lens sheet 2 Circular Fresnel lens sheet 3 Lenticular lens 4 Prism row 5, 6 Flat part

Claims (1)

[Claims] 1. A circular Fresnel lens sheet arranged on the light source side and a lenticular lens sheet arranged on the observation side. The lenticular lens sheet has a large number of lenticular lenses formed in parallel on the observation surface side. A rear projection type screen characterized in that a large number of prism rows are formed in parallel in the same direction as the lenticular lens on the incident surface side.