Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-03-07
2001-12-04
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S220000, C156S244250, C156S273300, C156S275500, C156S297000, C264S001340, C264S173100, C264S175000
Reexamination Certificate
active
06325880
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lenticular lens sheet to be used as the so-called rear projection screen for television which displays an image projected thereon from behind for observation from the front side thereof and, more particularly, to a lenticular lens sheet whose optical characteristics can be changed when used in combination with a Fresnel lens to form a rear projection screen.
2. Description of the Related Art
A lenticular lens sheet to be used as a screen for a rear projection television set, in which an image is projected on the screen from the back side of the screen and the image displayed on the screen is watched from the front side of the screen, is manufactured by the extrusion molding the press forming of a resin material prepared by kneading a mixture of a transparent or translucent base resin and a diffusing agent.
Such a lenticular lens sheet has a light entrance surface provided with linear lenticular elements having a cross section of a shape resembling a portion of a circle or an ellipse, and a light exit surface provided with a lens formed by alternately arranging shading black stripes and lenticular elements having a cross section of a shape resembling a portion of a circle or an ellipse. The lenticular elements of the light entrance surface and those of the light exit surface are formed integrally.
When manufacturing the conventional lenticular lens, the shape of the lenticular elements is designed according to desired optical characteristics of the lenticular lens, a die for molding the lenticular lens is fabricated on the basis of optical design data on the lenticular elements, and a resin is molded in the die to obtain the lenticular lens. However, it is very difficult to fabricate the die accurately conforming to the optical design data by state-of-the-art die fabricating techniques. For example, the sectional shape of the lenticular elements formed in the light entrance surface of the lenticular lens sheet is a half or a quarter of a circle of a radius in the range of 0.1 to 0.2 mm or a half of an ellipse. It is hardly possible to form accurately lenticular elements of a shape more complicated and minuter than the lenticular elements of the foregoing shape and size by state-of-the-art die fabricating techniques. When it is desired to obtain a lenticular lens sheet having further complicated optical characteristics, available means for adjusting the optical characteristics of the lenticular lens sheet have been only changing the diffusing agent contained in the resin material, changing the diffusing agent content of the resin base and/or changing the dimensions of the cross section of the lenticular elements which is a portion of a circle or an ellipse.
Some lenticular lens sheet is formed by putting together two lenticular lens sheets having linear lenticular elements with their lenticular elements extended perpendicularly to each other.
The rear projection screen using the conventional lenticular lens sheet is provided with linear lenticular elements. Therefore, the rear projection screen has uniform light exit characteristic for incident light rays falling on the light entrance surface at different incident angles, and the distribution of outgoing light rays is controlled in a limit range. Such problems may be solved by using a lenticular lens sheet formed by putting together two lenticular lens sheets having linear lenticular elements with their lenticular elements extended perpendicularly to each other, which unavoidably entails a light loss and increase in material cost because two lenticular lens sheets are used in two layers.
The lenticular lens sheet may be provided with lenses similar to a compound eye. However, it is very difficult for state-of-the-art die fabricating techniques, which form linear grooves of a circular cross section in a workpiece to form a die with the tip of a cutting tool, to fabricate a die for forming a lenticular lens sheet having lenticular elements having surfaces provided with minute ridges and furrows far smaller than those of the conventional lenticular lens sheet so as to conform accurately to optical design data. Use of an engraving process and a grinding process for fabricating a die will increases the costs of the die greatly.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a lenticular lens sheet provided with lenticular elements of a complicated, minute, elaborate shape which could not have been formed.
Another object of the present invention is to provide a method of fabricating a lenticular lens sheet provided with lenticular elements of a complicated, minute, elaborate shape which could not have been formed.
A lenticular lens sheet of the present invention having lenticular elements of a minute construction and excellent optical characteristics can be formed by a special method different from the conventional method without requiring an increase in the dimensional accuracy of a die.
A lenticular lens sheet of the present invention is intended to be used as a rear projection screen.
According to a first aspect of the present invention, a lenticular lens sheet comprises a base lenticular lens sheet having a light entrance surface provided with a plurality of lenticular elements, and a surface diffusing part having minute diffusing elements minuter than the lenticular elements and formed on the surfaces of the lenticular elements of the base lenticular lens sheet.
According to a second aspect of the present invention, a lenticular lens sheet comprises a base lenticular lens sheet provided on one surface thereof with lenticular elements, and a plastic film provided on one surface thereof with minute diffusing elements of an ionizing radiation setting resin, such as an ultraviolet setting resin (UV setting resin) or an electron beam setting resin (EB setting resin), and laminated to the base lenticular lens sheet.
According to a third aspect of the present invention, a lenticular lens sheet comprises a base lenticular lens sheet provided on one surface thereof with lenticular elements, and a surface diffusing part having minute diffusing elements minuter than the lenticular elements, and formed on the surfaces of the lenticular elements of the base lenticular lens sheet so as to extend perpendicularly to the lenticular elements of the base lenticular lens sheet by press working.
According to a fourth aspect of the present invention, a lenticular lens sheet comprises a base lenticular lens sheet having on one surface thereof lenticular elements provided with minute diffusing elements formed in the surfaces thereof by press working.
A method of fabricating a lenticular lens sheet comprising a base lenticular lens sheet provided on one surface thereof with lenticular elements, and a plastic film provided with a surface diffusing part having minute diffusing elements of an ionizing radiation setting resin, such as an UV setting resin or an electron beam setting resin, and laminated to the base lenticular lens sheet comprises the steps of:
(a) forming a plastic film provided on one surface thereof with a surface diffusing part having minute diffusing elements of an ionizing radiation setting resin by spreading the ionizing radiation setting resin over the circumference of a first roller having a circumference of a shape complementary to the minute diffusing elements, feeding a transparent or translucent plastic film onto the circumference of the first roller so as to wrap closely around the circumference of the first roller coated with the ionizing radiation setting resin and irradiating the ionizing radiation setting resin through the plastic film with ionizing radiation to set the ionizing radiation setting resin in minute diffusing elements on the surface of the plastic film; and
(b) laminating the plastic film provided with the minute diffusing elements of the ionizing radiation setting resin to a thermoplastic resin sheet forming a base lenticular lens sheet by feeding the plastic film and the thermopla
Watanabe Hitomu
Yamashita Yoshiyuki
Ball Michael W.
Dai Nippon Printing Co. Ltd.
Haran John T.
Parkhurst & Wendel LLP
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