Abstract:
By fitting a planar microlens array provided with one or more marks with a liquid crystal panel provided with one or more corresponding marks, it is possible to align the position of both exactly. The marks according to the present invention may comprise rod shapes, cross shapes, ring shapes, or square shapes, among others.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a liquid crystal display element formed by bonding a planar micro-lens array onto a liquid crystal panel. 
     2. Description of Related Art 
     As shown in FIGS. 7 and 8, a liquid crystal display element is formed by bonding a planar microlen array  200  onto a liquid crystal panel  100 . A gap is formed between the glass substrates  101  and  102  by a spacer  103 . The liquid crystal  105  is poured into the gap. On a surface of the glass substrate  101 , opposing a electrodes  101   a  are formed on the side of the liquid crystal  105 . On a surface of the other glass substrate  102  transparent pixel electrodes  102   a  are formed on the side of the liquid crystal  105 . Further, additional portions other than the transparent pixel electrodes  102   a  are formed which are not transparent, such as wiring, TFTS (thin film transistors), etc. 
     Recessed portions are formed on the glass substrate  201 . A resin of high refractive index is filled into and cured in the recessed portions, thereby obtaining a large number (a plurality) of small convex lens  202  which are bonded onto the liquid crystal panel  100  by a bond comprising a resin of low refractive index. The low refractive index serves to focus irradiated light through each of the plural convex lens into pixel electrodes (i.e., openings for the pixels)  102   a , so as to increase the brightness of an image projected upon the screen. 
     As another method of providing a large number of convex lens in the planar micro-lens array, the plural microlenses can also be directly formed a stamper by performing a stamping process on the surface of a glass substrate without forming recessed portions on the glass substrate. 
     In the case of bonding a planar micro-lens array  200  onto a liquid crystal panel  100 , if the position is off or if the two are misaligned, it becomes impossible to obtain correct focusing of the light irradiated onto the pixel electrodes (i.e., the openings for the pixels)  102   a.    
     Therefore, in the conventional art, marks  203  are formed in four corners at the same time when a large number of convex lens  202  are formed i.e., sequentially. As shown in FIG. 8, a planar microlens array  200  and a liquid crystal panel  100  are made to fit together by aligning marks  104  with the marks  203 , in which the marks  104  are formed on the bonding surface of the liquid crystal panel  100  in advance. 
     The marks  203 , formed on the side of the planar microlens array  200 , are formed with a resin of high refractive index. Therefore the marks  104  on the side of the liquid crystal panel  100  can be seen through the marks  203  which act as convex lens. As a result, it is difficult to fit the marks exactly. 
     SUMMARY OF THE INVENTION 
     To resolve the problem described above, the present invention includes a liquid crystal display element formed by bonding a planar microlens array onto a liquid crystal panel, comprising a plurality of convex lens and a first mark formed on the surface of said planar microlens array with a resin of high refractive index, and a second mark which corresponds to the first mark on the planar microlens array formed on the surface of the liquid crystal panel, wherein said first and second marks have corresponding forms so as to precisely fit and align the planar microlens array with the liquid crystal panel, by placing one of the first mark and the second mark into the space formed with the other of the first and the second mark. 
     The second mark on the side of the liquid crystal panel can be seen through the flat part which does not act as a lens of the planar microlens array, and therefore, easily aligning the planar array and panel. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 shows a cross-section view of a liquid crystal display element according to the present invention; 
     FIG. 2 shows an enlarged view of FIG. 1 from the direction of arrow B shown in FIG. 1; 
     FIG. 3 shows the same view as FIG. 2, showing another embodiment; 
     FIG. 4 shows the same view as FIG. 2, showing another embodiment; 
     FIG. 5 shows the same view as FIG. 2, showing another embodiment; 
     FIG. 6 shows the same view as FIG. 2, showing another embodiment; 
     FIG. 7 shows a cross-section view of a conventional liquid crystal display element; and 
     FIG. 8 is a view of FIG. 7 from the direction of the arrow A in FIG.  7 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, detailed explanations of the embodiments of the present invention will be given by referring to the attached drawings. Here, a liquid crystal display element is formed by bonding a planar microlens array onto a liquid crystal panel  10  with a resin of low refractive index  30 . 
     In the liquid crystal panel  10 , a gap is formed between glass substrates  11  and  12  by a spacer  13 , into which liquid crystal  14  is poured. On a surface of the glass substrate  12  there are formed opposing electrodes  12   a  at the side of the liquid crystal  14 . On a surface of the other glass substrate  11  there are formed transparent pixel electrodes  11   a  at the side of the liquid crystal  14 . Further, additional portions other than the transparent pixel electrodes  11   a  are formed which are not transparent, such as wiring, TFTs (thin film transistors), etc. 
     A first mark  15  is formed in four corners of the surface opposite to the planar microlens array  20  of the glass substrate  12 . The first mark  15  can be formed by, a screen printing process. As shown in FIG. 1, the first mark  15  is formed on the surface of the planar microlens array  20  facing the glass substrate  12  of the liquid crystal panel  10 . However, of course, the first mark may be formed in the surface opposite to the liquid crystal  14  of the glass substrate  12 . 
     On the other hand, in the planar microlens array  20 , a resin of high refractive index is applied onto the surface of the glass substrate  21 , which is molded with a stamper. A large number of convex lens  22  are formed by curing by use of ultra violet (UV) light or heat. Further, second marks  23  are formed in four corners at the same time when a large number of convex lens  22  are formed. 
     Here, the first mark  15  is rod-shaped. The second mark  23  comprises two rod-like mark elements  23   a . The sizes of the first mark  15  and the second mark  23  (mark elements  23   a ) are set up in order to mutually interfit the position of both exactly by piling or aligning the planar microlens array with the liquid crystal panel so as to place the first mark  15  between the mark elements  23   a  of the second mark  23 . 
     It should be noted that although only one pair of corresponding marks is described above, the invention may likewise be applied to two or more pairs of corresponding marks. 
     As shown in FIG. 3, the first mark  15  is cross-shaped and the second mark  23  comprises four angle-shaped mark elements  23   b . The first mark  15  and the mark elements  23   b  of the second mark  23  are aligned in order to mutually interfit the position of both exactly by piling or aligning the planar microlens array with the liquid crystal panel so as to place the first mark  15  into the gap formed between the mark elements  23   b  of the second mark  23 . 
     As shown in FIG. 4, the first mark  15  is cross-shaped and the second mark  23  comprises four round-shaped mark elements  23   c . As shown in FIG. 5, the first mark  15  is cross-shaped and the second mark  23  comprises four square-shaped mark elements  23   d . As shown in FIG. 6, the first mark  15  is round-shaped and the second mark  23  is ring-shaped. 
     The various embodiments mentioned above are all equally effective in permitting the planar array and the panel to be precisely aligned, thus resolving the drawback inherent in the prior art device. 
     In the examples shown in drawings, the first mark  15 , located at the side of the liquid crystal panel, is placed into the gap or the space formed by the second mark  23 , located at the side of the planar microlens array. However, this situation may be reversed, obtaining the same ease of alignment. 
     Moreover, in the drawings, examples are shown in which a resin of high refractive index is applied onto the surface of the glass substrate and a large number of convex lens are formed by a stamper. The present invention is not limited to such an arrangement, and can be equally applied to a liquid crystal display element in which recessed portions are formed on a glass substrate by etching and a resin of high refractive index is filled and cured in these recessed portions. 
     As is fully explained above, in accordance with the present invention, since the first and second marks, which are used when a liquid crystal display element is formed by bonding a planar micro-lens array onto a liquid crystal panel, are formed so as to precisely correspond with each other any marks at the side of the liquid crystal panel can be seen through the flat space  24  which does not act as lens of the planar microlens array. Therefore it becomes easy to align the position of the array and the panel.