Optical: systems and elements – Projection screen – Unitary sheet comprising plural refracting areas
Reexamination Certificate
2003-12-18
2004-11-09
Mahoney, Christopher E (Department: 2851)
Optical: systems and elements
Projection screen
Unitary sheet comprising plural refracting areas
C359S619000, C359S621000
Reexamination Certificate
active
06816307
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a rear projection screen, more particularly to large sized rear projection screen.
BACK GROUND OF THE INVENTION
The existing rear projection screen of prior art includes a Fresnel lens for collecting the image incident light, and a cylindrical lens array for receiving the image light collected by the said Fresnel lens, an ambient light absorbing portion and a image light effluence portion formed at the image-light exit side. As to the small sized screen for rear projection TV set, the cylindrical lens array in the screen can be manufactured by the integrated mold due to the size of the mold is small. But for the larger sized rear projection screen, such as more than 150 inches, if the cylindrical lens array in the screen still is made by the integrated mold, then the cost for the mold will be very high, that is, it is infeasible in view of economic point. Therefore, a large sized rear projection screen is normally formed by assembling a plurality of small rear projection screen. For example, a patent No. JP 1998-260478 disclosed an assembled large sized rear projection screen, which includes a plurality of unit screen in the horizontal and longitudinal direction, the sidepiece of each unit screen are fixed with the shade at the back side by screws. The screws are positioned at the inner side of the sidepiece of each unit screen instead of at the seam between two adjacent unit screens, result that the adjacent unit screens can be joint tightly almost without black strip shade lights. But there are still lots of image shading black spots at the position where the screws are fixed at the sidepiece of each unit screen, and the size of the image shading black spots are much larger than the ones of the pixels which form images. Accordingly the integrity and continuity of images are damaged.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a large sized rear projection screen, wherein there is not any shade for the images projected from rear, accordingly to provide with complete images without any defects.
The object of the present invention can be realized by the following large sized rear projection screen, which includes:
a Fresnel lens for collecting the image incident light, a cylindrical lens array for receiving the image light collected by the said Fresnel lens, and an ambient light absorbing portion and a image light effluence portion formed at the image-light exit side;
wherein the said cylindrical lens array comprises of a plurality of cylindrical lens elements, these cylindrical lens elements are separated from each other, that is independent, and in parallel, and arranged closely between adjacent cylindrical lens element, so that there are no luminous flux loss therebetween. A strengthening area, which is provided with a rigid reinforced member connecting with cylindrical lens elements on two sides thereof, is formed on the area being from their contact portion to the image-light exist-side surface between adjacent cylindrical lens elements. An ambient light absorbing portion is formed on the image-light exit side in the strengthening area.
With respect to the large sized rear projection screen with the above mentioned structure, as a strengthening area is formed in the cylindrical lens array which is made as outer side of the screen and reinforced members are formed within the strengthening area, so the impact strength, bending strength and rigidity of the full screen are improved, and the cylindrical lens will not deformed. In addition, since the said strengthening area is located in the area where no luminous flux loss is generated, and the strengthening area dose not shade any light projected from rear side, the images shown on the full screen possess the integrity and continuity without shadow or black spots caused by fixing screws of those prior art And the large sized rear projection screen of the present invention furthermore dose not have the wide striped shadows which possessed by the market available large sized screen assembled by multi-screen unit with sidepieces. As all strengthening area are located in the area where no luminous flux loss is generated and all strengthening area are provided with ambient light absorbing portion, so the ambient light absorbing portion of the complete screen according to this invention, i.e. the portion of the black grounding, is much higher than the ones of the conventional rear projection screen. Furthermore, due to the cylindrical lens array of the screen of present invention consist of a plurality of elements, i.e. breaking up the whole into parts, the process of manufacture is simple, the expensive huge mold for the conventional integrated rear projection screen is not required according to this invention.
In the said rear projection screen, each cylindrical lens elements can be formed by many integrated basic cylindrical lenses whose axial plane keep in parallel.
As to the large sized rear projection screen, since each cylindrical lens elements possesses many integrated basic cylindrical lenses, the number of the element decreases, the efficiency of assembling increases, the production cost of the screen can be reduced while the optical performance is not lost
In the said rear projection screen, each cylindrical lens elements may comprises single basic cylindrical lens.
As to the large sized rear projection screen of this invention, each cylindrical lens element is formed by many integrated basic cylindrical lenses, so that strengthening area can be formed between the single basic cylindrical lenses with rigid reinforced members provided therein, accordingly the rigidity of the whole screen is improved. In addition, the ambient light absorbing portions which are provided between basic cylindrical lenses are made of the same material, so the effect of light absorbing in the whole screen may remain consistent
In the rear projection screen of this invention, those cylindrical lens elements can be assembled with two kinds of cylindrical lens elements. The first kind of cylindrical lens elements are formed by many integrated basic cylindrical lenses whose axial plane keep in parallel, the second kind of cylindrical lens elements are formed by single basic cylindrical lenses.
In the rear projection screen of this invention, the first and second kind of cylindrical lens elements can be arranged in the manner that one or more first kind of cylindrical lens element(s) is/ are provided between two the second kind of cylindrical lens elements.
In the rear projection screen of this invention, the first and second kind of cylindrical lens elements can be arranged in the manner that one or more the second kind of cylindrical lens element(s) is/ are provided between two the first kind of cylindrical lens elements.
In the rear projection screen of this invention, the rigid reinforced members can be the shape of “Y” or “T”, wherein the two front wings are positioned at the image-light exit side. The screen is provided with a outer frame which is connected with the two ends of the reinforced members.
In the rear projection screen of this invention, the cross section of the reinforced members can be of polygonal wherein one of angles protrudes toward the direction of image-light exiting.
As to the large sized rear projection screen of this invention, since the front portion of the reinforced members projects toward out side, the contact between the cylindrical lenses and environmental objects can be avoided to prevent the cylindrical lens from abrading and damaging.
In the rear projection screen of this invention, the reinforced members can be made from rigid materials. At the out side of the reinforced members, i.e. the image-light exit side, a black oxide layer or black overcoating layer is provided.
In the rear projection screen of this invention, the rigid material can be metal, carbon fiber or non-metal material with high rigidity, wherein the metal can be light metal, for example aluminum alloy.
If the reinforced members adopt aluminum alloy, the weigh
Hochberg D. Peter
Mahoney Christopher E
Mellino Sean
Vieyra Katherine R.
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