Kuraray Co., Ltd.

Osamu Yoshimura

Ichiro Matsuzaki

Yoshihiro Kumagai

Masaki Ishii

Tatsuya Ueda

Hidehiro Tango

Shinichi Asano

Takao Kibushi

An object of the present invention is to provide a decorative illumination signboard capable of effectively downwardly emitting light while suppressing an upward emission of light with a simple configuration and a plastic sheet used in the decorative illumination signboard. The object can be accomplished by a plastic sheet having optical transparency which includes an exit surface and an incident surface on which a plurality of prism lines having a flat and smooth surface are arranged to be aligned. A shape of the prism in a cross-section perpendicular to a longitudinal direction of the prism line is formed by a side A on a lower side at an angle of &#x3b1; degrees to a normal line of the exit surface and a side B on an upper side at an angle of &#x3b2; degrees to the normal line of the exit surface and &#x3b1;&#x3c;&#x3b2;, and 40 degrees&#x2266;&#x3b2;&#x2266;80 degrees. An integral value of a downwardly emitted light flux is 55% or more of the total integral value of an upwardly emitted light flux and the downwardly emitting light flux when predetermined diffusion light enters one surface of the plastic sheet in a direction perpendicular to the plastic sheet.

Plastic sheet, and decorative illumination signboard

A lenticular lens sheet has arcuate-shaped warping such that the optical output lens side is the concave side, where, considering a chord B that connects points P and P3 to each other which are points on this approximate curve of arcurate shape and are of distance 150 mm from center line CL, and between which a distance is 300 mm, a distance to this chord B from the point P where this approximate curve and this center line intersect is represented by S , and, considering a chord B that connects an upper edge UE of this approximate curve to a point P 300 mm from the upper edge in the downwards direction, a distance to this chord B from the point P where the perpendicular from the central point P of this chord B intersects this approximate curve is represented by S , and, considering a chord B that connects a lower edge LE of this approximate curve to a point P 300 mm from the lower edge in the upwards direction, a distance to this chord B from the point P where the perpendicular from the central point P of this chord B intersects this approximate curve is represented by S , respectively, there exists a relationship satisfying S >S and S >S

Lenticular lens sheet

Provided is a plastic sheet for rear projection screens, which has a two or more multi-layered structure and which can be readily warped without being unfavorably swollen or waved. The plastic sheet is constructed to have a two or more multi-layered structure, in which the coefficient of linear expansion (at 20&deg; C.) of one layer is higher by at least 1.0&times;10 mm/(mm&middot;&deg;C.) than that of any other layer. In one embodiment of the plastic sheet, the layer of which the coefficient of linear expansion is higher than that of any other layer contains a fine particulate rubber material having a diameter of from 0.1 to 100 &mgr;m to such a degree that the rubber material content thereof is higher by at least 0.5% by weight than that of any other layer.

Plastic sheet for rear projection screens

A lenticular lens sheet capable of reducing the color shift and improving the overall light beam transmittance. The lenticular lens sheet has an incident side lenticular lens on its light beam incident side surface and further has an emergent side lenticular lens on its emergent side surface, with peak portions of the emergent side lenticular lens being formed at substantially convergent positions of the incident side lenticular lens. When an inter-lens distance at the sheet central portion is taken to be t.sub.0 and an inter-lens distance of an end portion of an viewable area of a rear-projection screen composed of this lenticular lens sheet is taken as t.sub.1, the rate of the inter-lens distances t.sub.0 and t.sub.1 is determined to satisfy 0.98.ltoreq.t.sub.1 /t.sub.0 .ltoreq.1.10.

Lenticular lens sheet capable of reducing color shift and improving

A rear-projection screen having at least a Fresnel lens and a light-diffusing member, and is characterized by having vertical-direction light diffusion properties greater at its upper and lower end portions than at its middle portion. For example, the light-diffusing member contains light-diffusing fine particles and has a vertical lenticular lens that diffuses light in the vertical direction, provided on the light-incident surface of the Fresnel lens. This decreases the rainbows caused by misdirected light and also improves the brightness at the border, without causing a lowering of peak gain.

Rear-projection screen

A lenticular lens sheet comprising lengthwise long lenticular lenses formed on the light incident-side surface and light emergent-side surface thereof, the lenticular lenses being constituted of cylindrical lenses each having a long dimension in the top and bottom direction of a screen when used, and satisfying

In a rear-projection screen comprising a Fresnel lens and a light-diffusing member such as a lenticular lens sheet, a rise angle in a central region of the Fresnel lens is smaller than a rise angle in an intermediate region thereof (e.g., the former is not larger than 3.degree. and the latter is larger than 3.degree. ). The rise angles may preferably gradually increase from the central region of the Fresnel lens toward the intermediate region thereof. The central region of the Fresnel lens may preferably be a region extending within the range of from 1/4 to 1/3 from the middle point of a diagonal of the rear-projection screen. Such a Fresnel lens is effective for improving white uniformity in the intermediate region of the rear-projection screen and eliminating color corn in the central region thereof.

Growing community of inventors

Chiyoda-ku, Japan

Osamu Yoshimura