Patent Publication Number: US-7901600-B2

Title: Method for producing an optical sheet

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     The present invention contains subject matter related to Japanese Patent Application JP 2006-129633 filed in the Japanese Patent Office on May 8, 2006, and Japanese Patent Application JP 2006-240839 filed in the Japanese Patent Office on Sep. 5, 2006, and is a divisional of U.S. patent application Ser. No. 11/470,877 filed on Sep. 7, 2006, now U.S. Pat. No. 7,467,886 the entire contents of which being incorporated herein by references. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an optical sheet having convex shape on the surface, a method for producing it, and a display apparatus including the optical sheet. 
     2. Description of the Related Art 
     In these years, cathode ray tubes (CRT), which were a mainstream of display apparatuses in the past, have been replaced by liquid crystal display apparatuses, since the liquid crystal display apparatuses have advantages such as low electrical power consumption, space-saving feature, and low cost. 
     There are several types of the liquid crystal display apparatuses when categorized by, for example, illumination methods in displaying images. As a representative example, a transmissive display apparatus which displays images by utilizing a light source arranged behind a liquid crystal panel can be cited. 
     In mobile products driven by a battery including such a display apparatus, the electrical power consumption of the display apparatus is enormously large, which is an obstacle to extend battery life. Specially, the ratio of the electrical power consumption of the backlight used in the display apparatuses is enormously large. Therefore, by reducing the electrical power consumption as much as possible, the battery life can be extended. In the result, practical values of the mobile products can be improved. However, it is not preferable that the electrical power consumption of the backlight is simply reduced, since luminance of the backlight is largely lowered, and thereby visibility of screen display of the display apparatus becomes unfavorable. Therefore, some measures to reduce the electrical power consumption of the backlight without largely lowering the luminance of the backlight have been proposed. 
     For example, in Japanese Unexamined Utility Model Application Publication No. 3-69184, a measure that an optical sheet having a plurality of pole prisms on the surface is arranged between a liquid crystal panel and a light source has been disclosed. A description will be specifically given of the optical sheet by using  FIG. 12  and  FIG. 13 . 
       FIG. 12  shows an example of a cross sectional structure of a transmissive display apparatus  100  including lens films  112  and  113  as the foregoing optical sheet.  FIG. 13  shows an enlarged view of part of a cross section of the lens film  112 . The display apparatus  100  mainly includes a liquid crystal panel  120  and an illumination system  110  (so-called backlight) arranged behind the liquid crystal panel  120  (that is, opposite side of an observer side). 
     The illumination system  110  includes a light source  111 , the lens films  112  and  113 , a diffusion sheet  114 , a lamp reflector  115 , an light guide plate  116 , and a reflecting sheet  117 . The liquid crystal panel  120  mainly includes a polarizing plate  121 , a transparent substrate  122 , a color filter  123 , a transparent electrode  124 , an orientation film  125 , a liquid crystal layer  126 , an orientation film  127 , a transparent pixel electrode  128 , a transparent substrate  129 , and a polarizing plate  130  in this order from the observer side. 
     In the display apparatus  100 , light emitted from the light source  111  is reflected by the lamp reflector  115  and the reflecting sheet  117 , directed in the direction of the liquid crystal panel  120 , spread over the whole area of the liquid crystal panel  120  by the light guide plate  116 , evenly diffused by the diffusion sheet  114 , condensed by the lens films  112  and  113 , and emitted to the liquid crystal panel  120 . The light entering the liquid crystal panel  120  is transmitted to the observer side according to a size of a voltage applied to each pixel by a not-shown drive circuit. 
     As above, by arranging the lens films  112  and  113  between the liquid crystal panel  120  and the diffusion sheet  114 , light emitted from the light source  111  can efficiently enter the liquid crystal panel  120 . In the result, the electrical power consumption of the backlight can be reduced without largely lowering luminance of the backlight. 
     For example, as described in Japanese Unexamined Patent Application Publication Nos. 4-356746, 5-314545, 5-325272, and 6-47806, the lens films  112  and  113  can be produced by coating a transparent base with an uncured hardening resin, pressing a mother die having a reversal shape of pole prisms onto the hardening resin, and curing the hardening resin in such a state to transcribe the pole prism shape. 
     SUMMARY OF THE INVENTION 
     However, in the lens film obtained by the foregoing manufacturing method, the lens film is largely warped to the hardening resin side due to shrinkage due to curing of the hardening resin. In particular, when the transparent base is thin, strength of the transparent base is lowered, and a ratio of shrinkage due to curing of the hardening resin is increased. In the result, the optical sheet is significantly warped to the hardening resin side. Even when large warpage is generated in the lens film as above, it is possible to press the warpage to arrange the lens film in the display apparatus. However, after the lens film is arranged in the display apparatus, the lens film is in contact with other optical parts in adjacent thereto in part due to the warpage. Therefore, there has been a disadvantage that Newton rings, flaws and the like are thereby generated, and the display quality of the display apparatus is lowered. 
     In view of the foregoing problem, in the present invention, it is desirable to provide an optical sheet with small warpage even in the case of a thin transparent base, a method for producing the optical sheet, and a display apparatus including the optical sheet. 
     An optical sheet of an embodiment of the invention is the one in which pole prisms made of a hardening resin are arranged along an extending direction on a transparent base made of a flexible material. Here, the transparent base is in contact with a valley between the pole prisms adjacent to each other. A display apparatus of an embodiment of the invention is the one including a panel, a light source emitting light for illuminating the panel, and one or a plurality of the optical sheets provided between the panel and the light source. 
     In the optical sheet and the display apparatus of the embodiment of the invention, the transparent base is in contact with the valley between the pole prisms adjacent to each other. Therefore, a layer not functioning as a prism, that is, a so-called skirt layer does not exist between the transparent base and the pole prism. Here, the expression “skirt layer does not exist” is a concept including a case that no skirt layer exists and a case that the skirt layer remains slightly (for example, 0.28 μm or less) due to an error in manufacturing or the like. Thereby, the height of the pole prism from the surface of the transparent base becomes the bare minimum, and a volume of the hardening resin becomes smaller than a case that the skirt layer exists. Further, since no skirt layer exists, there is almost no portion where the adjacent pole prisms are in contact with each other. 
     According to an embodiment of the invention, there is provided a method for producing an optical sheet including the following steps A to D: 
     A: a step of arranging an uncured hardening resin on a transparent base made of a flexible material; 
     B: a step of pressing a mother die having projections onto the hardening resin, and pressing tops of the projections onto the transparent base until the tops of the projections are in contact with the transparent base; 
     C: a step of forming the hardening resin by curing the hardening resin in a state that the projections are pressed onto the transparent base; and 
     D: a step of peeling the formed hardening resin from the mother die together with the transparent base. 
     In the method for producing an optical sheet of the embodiment of the invention, not only the projections of the mother die are pressed onto the hardening resin, but also the projections are pressed onto the transparent base. Therefore, a layer not functioning as a prism, that is, a so-called skirt layer does not exist between the transparent base and the pole prism. Thereby, the height of the pole prism from the surface of the transparent base becomes the bare minimum, and a volume of the hardening resin becomes smaller than the case that the skirt layer exists. Further, since no skirt layer exists, there is almost no portion where the adjacent pole prisms are in contact with each other. 
     According to the optical sheet, the method for producing the same, and the display apparatus of the embodiment of the invention, there is no skirt layer between the transparent base and the pole prism. Therefore, the volume of the hardening resin becomes smaller than the case that the skirt layer exists. Thereby, warpage of the optical sheet caused by shrinkage due to curing of the hardening resin can be largely decreased. Further, since there is almost no portion where the adjacent pole prisms are in contact with each other, strain caused by shrinkage due to the curing of the hardening resin is not organically bonded. Thereby, almost all warpages of the optical sheet can be eliminated. As a result, even in a case of having the transparent base thin, the optical sheet with small warpage can be realized. By arranging such an optical sheet with small warpage in the display apparatus, there is no possibility that Newton rings, flaws and the like are generated, and the display quality of the display apparatus can be improved. 
     Other and further objects, features and advantages of the invention will appear more fully from the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross section showing an example of a structure of a display apparatus of an embodiment of the invention; 
         FIG. 2A  is a cross section showing an example of a structure of an upper-side lens film; 
         FIG. 2B  is a cross section showing an example of a structure of a lower-side lens film; 
         FIG. 3A  is a cross section showing an example of another structure of the upper-side lens film; 
         FIG. 3B  is a cross section showing an example of another structure of the lower-side lens film; 
         FIG. 4  is a model view showing an example of a structure of a lens film manufacturing apparatus; 
         FIG. 5  is a cross section for explaining an example of operations of a transcriptional machinery of  FIG. 4 ; 
         FIG. 6  is a cross section for explaining an example of operations of another transcriptional machinery of  FIG. 4 ; 
         FIGS. 7A and 7B  are model views for explaining forms of warpage of the lens film; 
         FIG. 8  is a model view showing an example of measurement method of amount of warpage of the lens film; 
         FIG. 9  is a cross sectional photograph of the lens film; 
         FIG. 10  is a relational view for explaining a relation between a depth of a depression or a thickness of a skirt layer and an amount of warpage; 
         FIG. 11  is a model view showing an example of a measurement method of a relative luminance ratio of the lens film; 
         FIG. 12  is a cross section showing an example of a structure of a display apparatus of the related art; and 
         FIG. 13  is a cross section showing an example of a structure of a lens film of  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An embodiment of the invention will be hereinafter described in detail with reference to the drawings. 
       FIG. 1  shows a cross sectional structure of a display apparatus  1  of an embodiment of the invention. The display apparatus  1  is a transmissive display apparatus for displaying an image by active matrix drive. The display apparatus  1  includes a liquid crystal panel  20  and an illumination system  10  arranged behind the liquid crystal panel  20 . 
     The liquid crystal panel  20  has a laminated structure having a liquid crystal layer  26  between a transparent substrate  22  on an observer side and a transparent substrate  29  on the illumination system  10  side. Specifically, the liquid crystal panel  20  has a polarizing plate  21 , the transparent substrate  22 , a color filter  23 , a transparent electrode  24 , an orientation film  25 , the liquid crystal layer  26 , an orientation film  27 , a transparent pixel electrode  28 , a transparent substrate  29 , a polarizing plate  30 , and a diffusion sheet  31  in this order from the observer side. 
     The polarizing plates  21  and  30  are a kind of optical shutter, and let through only light (polarization) in a certain oscillation direction. The polarizing plates  21  and  30  are respectively arranged so that the polarizing axes are different from each other by 90 deg. Thereby, light emitted from the illumination system  10  is transmitted through or blocked by the liquid crystal layer  26 . 
     The transparent substrates  22  and  29  are made of a substrate transparent to visible light such as a plate glass. Though not shown, on the transparent substrate  29  on the illumination system  10  side, an active drive circuit including a TFT (Thin Film Transistor) as a drive device electrically connected to the transparent pixel electrode  28 , wiring and the like is formed. 
     In the color filter  23 , color filters for respectively color-separating light emitted from the illumination system  10  into three primary colors of red (R), green (G), and blue (B) are arranged. 
     The transparent electrode  24  is made of, for example, ITO (Indium Tin Oxide), and functions as a common opposed electrode. 
     The orientation films  25  and  27  are made of, for example, a polymer material such as polyimide, and perform orientation for the liquid crystal. 
     The liquid crystal layer  26  is made of, for example, VA (Vertical Alignment) mode liquid crystal, TN (Twisted Nematic) mode liquid crystal, or STN (Super Twisted Nematic) mode liquid crystal. The liquid crystal layer  26  has a function to transmit or block light emitted from the illumination system  10  for every pixel by a voltage applied from a not-shown drive circuit. 
     The transparent pixel electrode  28  is made of, for example, ITO, and functions as an electrode for each pixel. 
     The diffusion sheet  31  has a function to diffuse light emitted from the illumination system  10  in the same manner as a diffusion sheet  14  (described later), and decrease light unevenness. The diffusion sheet  31  is provided according to needs. 
     The illumination system  10  has: a lamination structure in which lens films  12 A and  13 A (optical sheet), a diffusion sheet  14 , a light guide plate  16 , and a reflecting sheet  17  are layered in the order from the observer side; a light source  11  arranged on the side face of the lamination structure; and a lamp reflector  15  arranged around the light source  11 . Part of the lamp reflector  15  is opened toward the laminated structure. As above, the illumination system  10  has a so-called edge-light structure. 
     The light source  11  is formed of a cold cathode fluorescent lamp called CCFL, a light emitting diode (LED) or the like. 
     The lamp reflector  15  has a function to reflect part of light emitted from the light source  11  in the direction of the light guide plate  16 . Thereby, light emitted from the light source  11  can be effectively utilized. 
     The light guide plate  16  has a function to totally reflect and concurrently propagate light emitted from the light source  11 , and to spread the light over the whole area of the liquid crystal panel  20 . Thereby, light emitted from the light source  11  can become flat light. 
     The reflecting sheet  17  has a function to reflect light to be leaked from the light guide plate  16  toward inside of the light guide plate  16 . Thereby, as with the foregoing lamp reflector  15 , light emitted from the light source  11  can be effectively utilized. 
     The diffusion sheet  14  has a function to diffuse flat light spread over the whole area of the liquid crystal panel  20  by the light guide plate  16  and to decrease light unevenness. Thereby, the whole area of the liquid crystal panel  20  is illuminated with light with uniform brightness. 
     The lens films  12 A and  13 A are, for example, as shown in enlarged views thereof in part in  FIGS. 2A and 2B , respectively structured in a manner that pole prisms  12 A 2  ( 13 A 2 ) having triangle pole shape are arranged on a transparent base  12 A 1  ( 13 A 1 ) in the extending direction. A stripe-shaped valley  12 A 3  ( 13 A 3 ) with a depth D 1  is provided between the adjacent pole prisms  12 A 2  ( 13 A 2 ). The pole prism  12 A 2  ( 13 A 2 ) has a sloping face  12 A 4  ( 13 A 4 ) extending to the surface of the transparent base  12 A 1  ( 13 A 1 ). The pole prism  12 A 2  and the pole prism  13 A 2  are arranged so that respective extending directions cross each other (for example, cross each other by 90 deg) and have a function to align and direct light direction in the direction of the liquid crystal panel  20 . 
     Here, the transparent base  12 A 1  ( 13 A 1 ) is a transparent resin sheet with a thickness D 2  made of a flexible material. The valley  12 A 3  ( 13 A 3 ) is in contact with the plane surface of the transparent base  12 A 1  ( 13 A 1 ). That is, no skirt layer exists between the transparent base  12 A 1  ( 13 A 1 ) and the pole prism  12 A 2  ( 13 A 2 ). Here, “no skirt layer exists” includes a case that no skirt layer exists and a case that a skirt layer remains slightly (for example, under 0.28 μm) due to an error in manufacturing or the like. That is, a thickness ΔDy of the skirt layer is totally 0 or an extremely small value. A distance D 3  between a bottom face and a top of the pole prism  12 A 2  ( 13 A 2 ) (that is, a height of the pole prism  12 A 2  ( 13 A 2 )) is totally equal to or almost equal to the depth D 1  of the valley  12 A 3  ( 13 A 3 ). 
     Instead of the transparent base  12 A 1  ( 13 A 1 ), as shown in  FIGS. 3A and 3B , it is possible to provide a transparent base  12 B 1  ( 13 B 1 ) having depressions  12 B 5  ( 13 B 5 ) with a depth ΔDx (D 1 -D 3 ) cyclically and having a convex curved face  12 B 6  ( 13 B 6 ) between the adjacent depressions  12 B 5  ( 13 B 5 ). However, in this case, a pole prism  12 B 2  ( 13 B 2 ) having a slope face  12 B 4  ( 13 B 4 ) extending to the inner wall of the depression  12 B 5  ( 13 B 5 ) of the transparent base  12 B 1  ( 13 B 1 ) and contacting with the surface of the transparent base  12 B 1  ( 13 B 1 ), and having a concave curved face contacting with the convex curved face  12 B 6  ( 13 B 6 ) on the transparent base  12 B 1  ( 13 B 1 ) side is provided on the transparent base  12 B 1  ( 13 B 1 ). There is no gap between the transparent base  12 B 1  ( 13 B 1 ) and the pole prism  12 B 2  ( 13 B 2 ). Therefore, a lens film  12 B ( 13 B) having the pole prism  12 B 2  ( 13 B 2 ) on the transparent base  12 B 1  ( 13 B 1 ) includes no skirt layer. Here, the distance D 3  between the concave curved face of the pole prism  12 B 2  ( 13 B 2 ) and the top (that is, a height of the pole prism  12 B 2  ( 13 B 2 )) is smaller than the depth D 1  of the trough  12 B 3  ( 13 B 3 ). 
     For simplifying descriptions, the transparent bases  12 A 1  ( 13 A 1 ),  12 B 1  ( 13 B 1 ) will be hereinafter generically named the transparent base  12 A 1  or the like. Other elements will be also hereinafter generically named in the same manner. 
     For the foregoing flexible material, a material having resistance or transmittance to energy used for forming the pole prism  12 A 2  or the like in the manufacturing process can be cited. For example, when the pole prism  12 A 2  or the like is formed by using active energy lines such as an ultraviolet ray and an electron ray, materials which transmit the active energy lines, for example, a polyester resin, an acrylic resin, a polycarbonate resin, a vinyl chloride resin, a polymethacrylic imide resin are preferable. 
     The pole prism  12 A 2  or the like is made of a hardening resin which is cured by heating or irradiating active energy lines such as an ultraviolet ray and an electron ray. As a hardening resin, for example, polyesters, an epoxy resin, a (meta) acrylate resin such as polyester (meta) acrylate, epoxy (meta) acrylate, and urethane (meta) acrylate can be cited. The (meta) acrylate resin is preferable since the (meta) acrylate resin has favorable optical characteristics. Further, as a main component of the hardening resin, a polymerization initiator by the active energy lines such as polyacrylate is preferably contained. In the case that the convex curved face  12 B 6  ( 13 B 6 ) is provided on the surface of the transparent base  12 B 1  ( 13 B 1 ) (refer to  FIGS. 3A and 3B ), when a refractive index of the foregoing hardening resin is smaller than that of the flexible material forming the transparent base  12 A 1  or the like, the convex curved face  12 B 6  ( 13 B 6 ) on the surface of the transparent base  12 B 1  ( 13 B 1 ) can function as a condenser. 
     Next, a description will be given of an example of a method of forming the lens film  12 A or the like with reference to  FIGS. 4 to 6 . First, a description will be given of a lens film manufacturing apparatus  30  used for forming the lens film  12 A or the like. 
       FIG. 4  shows a schematic structure of the lens film manufacturing apparatus  30 .  FIG. 5  shows an enlarged view of an example of a cross sectional structure in forming the lens film  12 A ( 13 A) by a transcriptional machinery  35  of  FIG. 4 .  FIG. 6  is an enlarged view of an example of a cross sectional structure in forming the lens film  12 B ( 13 B) by the transcriptional machinery  35  of  FIG. 4 . In  FIG. 4 , a hardening resin P is not shown. 
     The lens film manufacturing apparatus  30  includes an unwinding device  31  for supplying a transparent base S, a speed adjustment device  32  for adjusting feed speed of the transparent base S supplied from the unwinding device  31 , a resin supply device  33  for dropping the uncured hardening resin P on the transparent base S, a film thickness adjustment device  34  for adjusting a thickness of the hardening resin P dropped on the transparent base S, a transcriptional machinery  35  for transcribing a prism shape on the hardening resin P to form the lens film  12 A or the like, a mold-releasing device  36  for demolding the lens film  12 A or the like from the transcriptional machinery  35 , and a winding device  37  for winding the lens film  12 A or the like. 
     Here, the transcriptional machinery  35  has pressure rolls  35 A and  35 B which rotate centering on rotational axis X, a forming roll  35 C which rotates centering on rotational axis Y parallel to the rotational axis X, and a light source  35 D provided between the pressure rolls  35 A and  35 B. 
     The pressure roll  35 A feeds the transparent base S to the light source  35 D side while pressing the transparent base S coated with the hardening resin P with a given thickness by a given pressure from the transparent base S side in the direction of the forming roll  35 C. The pressure roll  35 B feeds the transparent base S from the light source  35 D side to the mold-releasing device  36  side while pressing the transparent base S having the hardening resin P formed in a given shape on the surface thereof by a given pressure from the transparent base S side in the direction of the forming roll  35 C. 
     As shown in  FIGS. 5 and 6 , the forming roll  35 C has a mother die in which pole projections  35 C- 1  with a reversal shape of the pole prism  12 A 2  or the like are arranged on the peripheral face along the extending direction. Rotational radius R 2  in the portion where the projection  35 C- 1  is formed in the forming roll  35 C (distance between the rotational axis Y of the forming roll  35 C and a top  35 C- 2  of the projection  35 C- 1 ) is larger than rotational radius R 1  in the portion where the projection  35 C- 1  is not formed (distance between the rotational axis Y of the forming roll  35 C and a surface  35 C- 3  where the projection  35 C- 1  is not formed). Thereby, when the projection  35 C- 1  is pressed onto the transparent base S, there is no possibility that the surface  35 C- 3  not formed with the projection  35 C- 1  is in contact with the transparent base S. Therefore, the top  35 C- 2  of the projection  35 C- 1  can be surely pressed onto the transparent base S. Therefore, in the transcriptional machinery  35 , by appropriately adjusting a pressure with which the top  35 C- 2  of the projection  35 C- 1  is pressed onto the transparent base S, a state that the top  35 C- 2  is in contact with the surface of the transparent base S can be maintained. Further, it is also possible that by pressing the top  35 C- 2  into the transparent base S, depressions and a convex curved face between adjacent depressions are formed on the surface of the transparent base S. 
     The light source  35 D irradiates an active energy line L such as an ultraviolet ray and an electron ray from the transparent base S side to the hardening resin P pressed onto the forming roll  35 C by the pressure rolls  35 A and  35 B. 
     When the foregoing lens film manufacturing apparatus  30  starts operations, the transparent base S supplied from the unwinding device  31  is adjusted to a given speed by the speed adjustment device  32 , and the uncured hardening resin P is dropped on the transparent base S by the resin supply device  33 . The dropped hardening resin P is adjusted to a given thickness by the film thickness adjustment device  34 . The hardening resin P with the film thickness adjusted is put into the transcriptional machinery  35  with the surface thereof facing to the forming roll  35 B side. Then, the hardening resin P is pressed onto the forming roll  35 B from the transparent base S side by the pressure rolls  35 A and  35 B, and a shape of the pole prism  12 A 2  or the like is transcribed. 
     When the pole prism  12 A 2  ( 13 A 2 ) is formed, as shown in  FIG. 5 , pressure is applied by the pressure rolls  35 A and  35 B until the top  35 C- 2  of the projection  35 B- 1  is in contact with the transparent base S. Thereby, there is almost no portion where the adjacent pole hardening resin P is in contact with each other. Meanwhile, when the pole prism  12 B 2  ( 13 B 2 ) is formed, as shown in  FIG. 6 , pressure is applied by the pressure rolls  35 A and  35 B until the top  35 C- 2  of the projection  35 B- 1  is pressed into the transparent base S. Thereby, there is almost no portion where the adjacent pole hardening resin P is in contact with each other. In addition, the depression  12 B 5  ( 13 B 5 ) is formed in the pressed portion, and the convex curved face  12 B 6  ( 13 B 6 ) is formed between the adjacent depressions  12 B 5  ( 13 B 5 ). 
     Subsequently, light L emitted from the light source  35 D is irradiated to the hardening resin P through the transparent base  12 A 1  or the like in a state that the top  35 C- 2  of the projection  35 B- 1  is pressed onto the transparent base  12 A 1  or the like. Thereby, a shape transcribed on the hardening resin P is fixed. In the result, the pole prism  12 A 2  ( 13 A 2 ) is formed on the transparent base  12 A 1  ( 13 A 1 ), and the pole prism  12 B 2  ( 13 B 2 ) is formed on the transparent base  12 B 13  ( 13 B 13 ). After that, the transparent base  12 B 1  or the like is released from the transcriptional machinery  35  by the mold-releasing device  36  together with the pole prism  12 A 2  or the like, and the released resultant is wound by the winding device  37 . As above, the lens film  12 A or the like of this embodiment is formed. 
     The deeper a depth ΔDx of the depression  12 B 5  ( 13 B 5 ) is, the smaller a curvature radius of the curved face  12 B 6  ( 13 B 6 ) can be. However, when a pressure of the pressure rolls  35 A and  35 B is excessively increased to deepen the depression  12 B 5  ( 13 B 5 ), there is a possibility that the depression  12 B 5  ( 13 B 5 ) in the transparent base  12 B 1  ( 13 B 1 ) becomes white, and thus a light transmittance decreases. Therefore, the depth ΔDx of the depression  12 B 5  ( 13 B 5 ) is preferably a depth to an extent that no whitening is caused at the transparent base  12 B 1  ( 13 B 1 ) (about 10% or less of thickness D 2  of the transparent base  12 B ( 13 B 1 )). 
     Next, basic operations in displaying an image in the display apparatus  1  including the lens film  12 A or the like formed as above will be described. 
     First, in the illumination system  10 , part of light emitted from the light source  11  directly enters the light guide plate  16 , and the rest of light thereof is reflected by the lamp reflector  15  and then enters the light guide plate  16 . The light entering the light guide plate  16  is emitted from the top face of the light guide plate  16 , evenly diffused by the diffusion sheet  14 , oriented by the lens film  12 A 13 , and emitted to the liquid crystal panel  20 . 
     In the liquid crystal panel  2 , incident light from the illumination system  10  is transmitted according to a size of a voltage applied for every pixel between the transparent pixel electrode  28  and the transparent electrode  24  as an opposed electrode, color-separated by the color filter  23 , and emitted to the observer side. Thereby, color images are displayed. 
     Next, a description will be given of effects of the lens film  12 A or the like of this embodiment in comparison with the lens film  112  of related art shown in  FIG. 13 . 
     The lens film  112  of related art is different from the lens film  12 A or the like of this embodiment mainly in that the lens film  112  has a pole prism  112 - 2  on a transparent base  112 - 1  with a skirt layer  112 - 5  in between. As described above, the skirt layer  112 - 5  is a layer not functioning as a prism, which is not necessary in the optical design. However, in the past, when an uncured hardening resin is cured to transcribe a shape of the pole prism  112 - 2 , the skirt layer  112 - 5  having a uniform thickness is provided to prevent deterioration of transcription characteristics caused by shrinkage due to curing of the hardening resin. 
     However, when such a skirt layer  112 - 5  is provided, a volume of the uncured hardening resin necessary for forming the pole prism  112 - 2  is naturally increased, compared to a case in which no skirt layer  112 - 5  is provided. Further, the adjacent pole prisms  112 - 2  are in contact with each other with the skirt layer  112 - 5  in between, strain caused by shrinkage due to curing of the hardening resin is organically bonded. Therefore, shrinkage due to curing of the hardening resin becomes large. In the result, large warpage (warpage on the plus side) as shown in  FIG. 7B  is generated in the lens film  112 . 
     An amount of warpage can be, for example, measured by using a height gauge  210  arranged on a level block  200  as shown in  FIG. 8 . The height gauge  210  includes a scale  211  which extends in the direction perpendicular to the level block  210 , a movable section  212  which is arranged movably and extends in the direction parallel to the level block  200 , and a base  213  which is connected to an end of the scale  211  and supports the scale  211 . A measurement target  220  is placed with the surface of the side warped in a state of a convex upward on the level block  200 , the movable section  212  is quietly dropped from upward of the measurement target  220 , and a scale indicated in the scale  211  from a position of the movable section  212  at a moment when the bottom face of the movable section  212  is in contact with the concave surface of the measurement target  220  is read, and thereby measurement is performed. As an apparatus allowing such measurement, for example, HD-30A of MITUTOYO can be cited. When the surface on the side formed with a prism is warped in a state of a convex as shown in  FIG. 7A , it is described that being warped to the minus side. When the surface on the side opposite of the side formed with a prism (resin base side) is warped in a state of a convex as shown in  FIG. 7B , it is described that being warped to the plus side. 
     Even when large warpage is generated in the lens film  112  as above, it is possible to press the warpage and arrange the lens film  112  in the display apparatus  1 . However, when the lens film  112  is arranged in the display apparatus  1 , it is often the case that the lens film  112  is partly in contact with other optical component (diffusion sheets  14  and  31 ) or the like adjacent thereto due to the warpage, and thereby Newton rings, flaws and the like are generated and the display quality of the display apparatus  1  is lowered. Such an issue has been largely generated particularly in the case of mobile usage in which a gap in the display apparatus  1  is slightly provided. Such a case has lead to lowering of the yield. 
     Meanwhile, the lens film  12 A or the like of this embodiment is formed so that the valley  12 A 3  or the like is in contact with the transparent base  12 A 1  or the like by using the foregoing producing method. Thereby, the skirt layer regarded as a necessary component in the past is excluded, and a volume of the uncured hardening resin P necessary in forming the pole prism  12 A 2  or the like is reduced. In the result, shrinkage due to curing of the hardening resin P largely decreases. Further, since there is almost no portion where the adjacent pole prisms  12 A 2  or the like are in contact with each other, strain caused by shrinkage due to the curing of the hardening resin P is not organically bonded. Thereby, almost all warpages of the lens film  12 A or the like can be eliminated. 
     Further, when the depression  12 B 5  ( 13 B 5 ) is formed by using the foregoing producing method, stress is generated in the direction opposite to the direction of stress due to shrinkage of the pole prism  12 B 2  ( 13 B 2 ) in the vicinity of the depression  12 B 5  ( 13 B 5 ) of the transparent base  12 B 1  ( 13 B 1 ). In the result, an amount of warpage generated by the lens film  12 B largely decreases. Therefore, there is no possibility that Newton rings, flaws or the like are generated, and the display quality of the display apparatus  1  is significantly favorable. 
     In the foregoing producing method, it has been confirmed that in transcribing a shape of the pole prism  12 A 2  or the like by curing the uncured hardening resin P, there is no possibility that transcription characteristics are not deteriorated by shrinkage due to curing of the hardening resin P even when no skirt layer is provided (refer to a cross sectional photograph of  FIG. 9 ). Therefore, there is no possibility that the display quality of the display apparatus  1  is deteriorated even when no skirt layer is provided. 
     Further, in this embodiment, when the depression  12 B 5  ( 13 B 5 ) is formed on the surface of the transparent base  12 B 1  ( 13 B 1 ), the convex curved face  12 B 6  ( 13 B 6 ) is formed between each depression  12 B 5  ( 13 B 5 ) accordingly. Therefore, by making the curved face  12 B 6  ( 13 B 6 ) function as a condenser, front luminance can be improved. 
     In the field of mobile devices, display apparatuses are desired to become thinner. Each component composing the display apparatuses are demanded to become thinner as long as possible. A description will be given thereof with reference to  FIG. 13 . To make the lens film  112  thinner, for example, the transparent base  112 - 1  of the lens film  112  may be made thin. However, when the transparent base  112 - 1  is made thin, strength of the transparent base  112 - 1  is lowered, and a rate of shrinkage due to curing of a hardening resin is increased. Therefore, the lens film  112  is significantly warped to the pole prism  112 - 2  side. Then, the depth D 1  of the valley  112 - 3  of the pole prism  112 - 2  may be made shallow instead of the transparent base  112 - 1 . However, the depth D 1  of the valley  112 - 3  is made simply shallow, a slope angle of the slope face  112 - 4  becomes small, and front luminance is lowered. Therefore, a pitch of the pole prism  112 - 2  should be decreased while maintaining the slope angle of the slope face  112 - 4  of the pole prism  112 - 2 . However, when the pitch of the pole prism  112 - 2  is excessively decreased, the front luminance is decreased in reality. As a result, utility of the lens film  112  provided for the purpose of improving luminance is decreased. Therefore, it is found that in the case of  FIG. 13 , to make the lens film  112  thinner without decreasing front luminance, there are only the following methods. One method is to eliminate the skirt layer  112 - 5  located under the pole prism  112 - 2 . The other method is to make the transparent base  112 - 1  thin. However, in the past, there is no idea to eliminate the skirt layer  112 - 5  since the skirt layer  112 - 5  is actively provided as described above. Meanwhile, when the transparent base  112 - 1  is made thin, large warpage is generated. Therefore, it has been necessary to make the transparent base  112 - 1  thick to some degree (for example, about 50 μm). 
     Meanwhile, in the lens film  12 A or the like of this embodiment, the skirt layer which has been regarded as a necessary component is actively eliminated, the transparent base  12 A 1  or the like and the valley  12 A 3  or the like are in contact with each other, and portions where the adjacent triangle pole-shaped hardening resin are in contact with each other are almost eliminated. Thereby, strain generated curing and shrinkage of the adjacent triangle pole-shaped hardening resin is not organically bonded. Therefore, warpage of the lens film  12 A or the like can be almost eliminated. 
     In the result, even when the transparent base  12 A 1  or the like is made thin, there is no possibility that the lens film  12 A or the like is warped. Therefore, for example, it is possible that the whole thickness of the lens film  12 A or the like is made thin by making the transparent base  12 A 1  or the like thin. Further, it is possible that front luminance is increased almost without changing the whole thickness of the lens film  12 A or the like by making the transparent base  12 A 1  or the like thin and making the pitch of the pole prism  12 A 2  or the like large. 
     EXAMPLES 
     Next, a description will be given of examples of the lens film  12 A or the like of this embodiment in comparison with the lens film  112  of comparative examples. 
     In the lens film  12 A or the like according to the examples, the width (pitch) in the arrangement direction of the pole prism  12 A 2  or the like was 31 μm, the depth D 1  of the valley  12 A 3  or the like was 15 μm, the angle of the top (apex angle) of the pole prism  12 A 2  or the like was 90 deg, and the thickness D 2  of the transparent base  12 A 1  or the like was 50 μm. In addition, the depth of the depression  12 B 5  ( 13 B 5 ) (−ΔDx (=D 3 −D 1 )) was −4.31 μm, −3.13 μm, −2.46 μm, −2.04 μm, −1.21 μm, −0.5 μm, +0.0 μm, or +0.25 μm (refer to Table 1). The depth (−ΔDx) of +0.0 μm means that no skirt layer exists. The depth (−ΔDx) of +0.25 μm means that the skirt layer slightly remains due to an error in manufacturing or the like, that is, means that the skirt layer does not exist practically. 
     Meanwhile, in the lens film  112  according to the comparative examples, as in the foregoing examples, the width (pitch) in the arrangement direction of the pole prism  112 - 2  was 31 μm, the depth D 1  of a valley  112 - 3  was 15 μm, the angle of the top (apex angle) of the pole prism  112 - 2  was 90 deg, and the thickness D 2  of the transparent base  112 - 1  was 50 μm. In addition, the thickness of the skirt layer  112 - 5  (ΔDy(=D 3 −D 1 )) was +0.5 μm, +6.5 μm, +17.5 μm, +25.5 μm, or 34.5 μm (refer to Table 1). 
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Thickness 
                   
                 Amount 
                   
                   
                   
                   
               
               
                   
                 Depth of 
                 of skirt 
                   
                 of 
               
               
                   
                 depression 
                 layer 
                 Pitch 
                 warpage 
                 D2 
                 D1 
                 D3 
                 H 
               
               
                   
                 −ΔDx (μm) 
                 −ΔDy (μm) 
                 (μm) 
                 (μm) 
                 (μm) 
                 (μm) 
                 (μm) 
                 (μm) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Example 
                 −4.31 
                 — 
                 31 
                 0.0 
                 50 
                 15 
                 10.69 
                 60.5 
               
               
                 Example 
                 −3.13 
                 — 
                 31 
                 0.0 
                 50 
                 15 
                 11.87 
                 61.8 
               
               
                 Example 
                 −2.46 
                 — 
                 31 
                 0.0 
                 50 
                 15 
                 12.54 
                 62.5 
               
               
                 Example 
                 −2.04 
                 — 
                 31 
                 0.0 
                 50 
                 15 
                 12.96 
                 63.0 
               
               
                 Example 
                 −1.21 
                 — 
                 31 
                 0.0 
                 50 
                 15 
                 13.79 
                 63.8 
               
               
                 Example 
                 −0.5 
                 — 
                 31 
                 0.0 
                 50 
                 15 
                 14.5 
                 64.5 
               
               
                 Example 
                 +0.0 
                 +0.0 
                 31 
                 0.0 
                 50 
                 15 
                 15 
                 65 
               
               
                 Example 
                 +0.25 
                 +0.25 
                 31 
                 0.0 
                 50 
                 15 
                 15.25 
                 65.2 
               
               
                 Comparative 
                 — 
                 +0.5 
                 31 
                 1.11 
                 50 
                 15 
                 15.5 
                 65.5 
               
               
                 example 
               
               
                 Comparative 
                 — 
                 +6.5 
                 31 
                 1.67 
                 50 
                 15 
                 21.5 
                 71.5 
               
               
                 example 
               
               
                 Comparative 
                 — 
                 +17.5 
                 31 
                 1.8 
                 50 
                 15 
                 32.5 
                 82.5 
               
               
                 example 
               
               
                 Comparative 
                 — 
                 +25.5 
                 31 
                 3.72 
                 50 
                 15 
                 40.5 
                 90.5 
               
               
                 example 
               
               
                 Comparative 
                 — 
                 +34.5 
                 31 
                 6.73 
                 50 
                 15 
                 49.5 
                 99.5 
               
               
                 example 
               
               
                   
               
            
           
         
       
     
       FIG. 10  shows a relation between the depth (−ΔDx) of the depression  12 B 5  ( 13 B 5 ) of the lens film  12 A or the like according to the foregoing examples and the amount of warpage in the left side of the figure, and shows a relation between the thickness ΔDy of the skirt layer  112 - 5  of the lens film  112  according to the foregoing comparative examples and the amount of warpage in the right side of the figure. 
     From  FIG. 10 , it was found that in the examples, the amount of warpage of the lens film  12 A or the like was 0 regardless of the depth of the depression  12 B 5  ( 13 B 5 ) including that the transparent base  12 A 1  ( 13 A 1 ) was in contact with the valley  12 A 3  ( 13 B 1 ). Therefore, in the examples, there is no possibility that Newton rings, flaws and the like are generated, the display quality of the display apparatus  1  is enormously favorable, and thus the examples are enormously suitable for mobile usage. 
     Meanwhile, it was found that in the comparative examples, the amount of warpage of the lens film  112  was extremely large, and even if the skirt layer  112 - 5  slightly existed, the amount of warpage of the lens film  112  was drastically increased. That is, it was found that regarding the amount of warpage, a discontinuity existed depending on the presence of the skirt layer  112 - 5 . Therefore, in the comparative examples, there is an enormous possibility that Newton rings, flaws and the like are generated, the display quality of the display apparatus  1  is easily lowered, and thus the comparative examples are not suitable for mobile usage. 
     Table 2 shows relative luminance ratios of the lens film  12 A or the like with the depth (−ΔDx) of −4.31 μm, −3.13 μm, −2.46 μm, −2.04 μm, or −1.21 μm where luminance of the lens film  12 A or the like was 1 when the depth (−ΔDx) of the depression  12 B 5  ( 13 B 5 ) was +0.0 μm. For reference, curvature radius of the curved face  12 B 6  ( 13 B 6 ) corresponding to the depth (−ΔDx) of the depression  12 B 5  ( 13 B 5 ) are shown. 
     
       
         
           
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Depth of depression 
                 Curvature radius 
                 Relative luminance 
               
               
                 (−ΔDx (μm)) 
                 (μm) 
                 ratio 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 −4.31 
                 30 
                 0.998 
               
               
                 −3.13 
                 40 
                 1.0245 
               
               
                 −2.46 
                 50 
                 1.0246 
               
               
                 −2.04 
                 60 
                 1.0270 
               
               
                 −1.21 
                 100 
                 1.0400 
               
               
                 0 
                 10000 
                 1 
               
               
                   
               
            
           
         
       
     
     Light luminance outputted through the lens film  12 A or the like was measured by, for example, a color luminance meter  300  as shown in  FIG. 11 . The color luminance meter  300  is fixed on a support section  320  which is fixed on a level block  310  and extends in the direction perpendicular to the level block  310  with an aperture  300 A for taking light downward. By taking in light outputted from a backlight unit  330  placed on the level block  310  from the aperture  300 A, luminance of the light is measured. The lens film  12 A or the like was placed on the backlight unit  330 , and luminance when the backlight unit  330  was turned on was measured. Next, the lens film  12 A or the like was not placed on the backlight unit  330 , and luminance when the backlight unit  330  was turned on was measured. Thereby, the relative luminance ratio was obtained. 
     From Table 2, it was found that when the depth ΔDx of the depression  12 B 5  ( 13 B 5 ) was deepened, a range where the relative luminance ratio was larger than 1 existed. Therefore, by setting the depth (−ΔDx) of the depression  12 B 5  ( 13 B 5 ) within the range, the amount of warpage generated in the lens film  12 A or the like could be largely decreased, in addition, the front luminance could be improved. 
     In reality, the relative luminance ratio is changed according to the size of the curvature radius. However, the size of the curvature radius when the relative luminance ratio is larger than 1 is changed according to the width (pitch) in the arrangement direction of the pole prism  12 B 2  ( 13 B 2 ), the depth D 3  of the valley  12 B 3  ( 13 B 3 ), and the angle of the top (apex angle) of the pole prism  12 B 2  ( 13 B 2 ). Therefore, the depth (−ΔDx) of the depression  12 B 5  ( 13 B 5 ) with which the relative luminance ratio becomes larger than 1 is difficult to be determined categorically. As a combination frequently used practically, the depth (−ΔDx) of the depression  12 B 5  ( 13 B 5 ) with which the relative luminance ratio becomes larger than 1 is smaller than 0 μm, and about −4 μm or more, considering that the depth D 3  of the valley  12 B 3  ( 13 B 3 ) is almost half of the width (pitch) in the arrangement direction of the pole prism  12 B 2  ( 13 B 2 ), and the angle of the top (apex angle) of the pole prism  12 B 2  ( 13 B 2 ) is about 90 deg. 
     Table 3 shows the amount of warpage when the transparent base  12 A 1  or the like of the lens film  12 A or the like according to the examples was an existing typical thickness (50 μm) or less, and the amount of warpage when the transparent base  122 - 1  of the lens film  112  according to the comparative examples was an existing typical thickness (50 μm) or more. In Table 3, when the depression  12 B 5  ( 13 B 5 ) was provided, D 1 /D 2  was used as a thickness ratio. When the depth (−ΔDx) was +0.0 μm, +0.25 μm, and +0.28 μm, and when the skirt layer  112 - 5  existed, D 3 /D 2  was used as a thickness ratio. 
     
       
         
           
               
               
               
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                 Pitch 
                 D2 
                 D1 
                 D3 
                 H 
                 D1/D2 
                 D3/D2 
                 −ΔDx 
                 ΔDy 
                 Amount of 
               
               
                   
                 (μm) 
                 (μm) 
                 (μm) 
                 (μm) 
                 (μm) 
                 (μm) 
                 (μm) 
                 (μm) 
                 (μm) 
                 warpage (mm) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Example a 
                 34 
                 25 
                 15.8 
                 16.1 
                 41.1 
                 — 
                 0.64 
                 — 
                 +0.28 
                 0.0 
               
               
                 Example b 
                 19 
                 25 
                 8.6 
                 8.1 
                 33.1 
                 0.34 
                 — 
                 −0.5 
                 — 
                 0.0 
               
               
                 Example c 
                 34 
                 25 
                 15.8 
                 14.8 
                 39.8 
                 0.63 
                 — 
                 −1.0 
                 — 
                 0.0 
               
               
                 Example d 
                 50 
                 25 
                 23.3 
                 22.8 
                 47.8 
                 1.02 
                 — 
                 −0.5 
                 — 
                 0.0 
               
               
                 Example e 
                 34 
                 50 
                 15.8 
                 15.3 
                 65.3 
                 0.32 
                 — 
                 −0.5 
                 — 
                 0.0 
               
               
                 Example f 
                 31 
                 50 
                 15 
                 14.5 
                 64.5 
                 0.3 
                 — 
                 −0.5 
                 — 
                 0.0 
               
               
                 Example g 
                 31 
                 50 
                 15 
                 15 
                 65.0 
                 — 
                 0.3 
                 +0.0 
                 +0.0 
                 0.0 
               
               
                 Example h 
                 34 
                 50 
                 15.8 
                 16.1 
                 65.1 
                 — 
                 0.33 
                 +0.25 
                 +0.25 
                 0.0 
               
               
                 Comparative example I 
                 24 
                 50 
                 11 
                 13 
                 63.0 
                 — 
                 0.26 
                   
                 +2.0 
                 1.9 
               
               
                 Comparative example k 
                 50 
                 125 
                 25 
                 30 
                 155 
                 — 
                 0.24 
                   
                 +5.0 
                 0.4 
               
               
                   
               
            
           
         
       
     
     From Table 3, it was found that in Comparative example i in which the thickness D 2  of the transparent base  112 - 1  was an existing typical thickness (50 μm), and the thickness ΔDy of the skirt layer  112 - 5  was +2.0 μm, the large warpage was generated. Therefore, in the past, to decrease the warpage of the lens film  112 , the thickness D 2  of the transparent base  112 - 1  was thick as in Comparative example k. 
     Meanwhile, in the examples, by practically eliminating the skirt layer by setting the thickness ΔDy of the skirt layer to +0.25 μm as in Example h, or by totally eliminating the skirt layer by setting the thickness ΔDy of the skirt layer to +0.0 μm as in Example g, the warpage could be eliminated without making the thickness D 2  of the transparent base  12 A 1  ( 13 A 1 ) thin. Further, for example, by setting the depth (−ΔDx) of the depression  12 B 5  ( 13 B 5 ) to −0.5 μm as in Example f or Example e, for example, the warpage could be eliminated without making the thickness D 2  of the transparent base  12 B 1  ( 13 B 1 ) thick. 
     Further, in the examples, for example, as in Examples b, c, and d, by providing the depression  12 B 5  ( 13 B 5 ) and setting the thickness D 2  of the transparent base  12 B 1  ( 13 B 1 ) thinner than the existing thickness (25 μm), the warpage could be eliminated. Then, in Example d, height H of the lens film  12 B ( 13 B) was lower than that of the existing height, and the height D 3  of the pole prism  12 B 2  ( 13 B 2 ) and the pitch of the pole prism  12 B 2  ( 13 B 2 ) were increased. Therefore, the front luminance could be increased without increasing the height H of the lens film  12 B ( 13 B) than the existing height. Further, in Example b, since the height D 3  of the pole prism  12 A 2  or the like and the pitch of the pole prism  12 B 2  ( 13 B 2 ) were decreased, the lens film  12 B ( 13 B) could be thinner. 
     Further, in the examples, for example, as in Example a, by practically eliminating the skirt layer by setting the thickness ΔDy of the skirt layer to +0.28 μm and setting the thickness D 2  of the transparent base  12 A 1  ( 13 A 1 ) thinner than the existing thickness (25 μm), the warpage could be eliminated. 
     The foregoing results will be summarized in view from the ratios (D 1 /D 2 , D 3 /D 2 ). By adjusting D 1 , D 2 , and D 3  to satisfy D 1 /D 2 ≧0.30 and D 3 /D 2 ≧0.30 and practically or totally eliminating the skirt layer, and further by providing the depression  12 B 5  ( 13 B 5 ), it is possible to make the total thickness of the lens film  12 A or the like thin without generating warpage, and further to increase the front luminance. 
     While the invention has been described with reference to the embodiment and the examples, the invention is not limited to the embodiment and the like, and various modifications may be made. 
     For example, in the foregoing embodiment and the like, the lens film  12 A or the like respectively has the triangle pole-shaped pole prism  12 A 2  or the like. For example, the lens film  12 A or the like may have an aspherical microlens. 
     Further, in the foregoing embodiment and the like, the lens film  12 A or the like has a condensing function. However, the lens film  12 A or the like also has a diffusion function. In this case, micro projections may be provided on the rear face of the lens film  12 A or the like, or the rear face of the lens film  12 A or the like may be coated with a diffusion material. Otherwise, the lens film  12 A or the like itself may contain a diffusion material. Otherwise, a diffusion sheet or a diffusion plate may be glued on the surface of the lens film  12 A or the like. 
     Further, in the foregoing embodiment and the like, the lens film  12 A or the like is respectively arranged so that light of the light source  11  enters from the transparent base  12 A 1  or the like side. However, it is possible that in another display apparatus, the lens film  12 A or the like may be arranged so that light of the light source enters from the side opposite to the transparent base  12 A 1  or the like, that is, from the pole prism  12 A 2  or the like side. 
     Further, in the foregoing embodiment and the like, by adjusting the thickness of the hardening resin P dropped on the transparent base S by the resin supply device  33  to a given thickness by the film thickness adjustment device  34 , the transparent base S is coated with the uncured hardening resin P. However, the uncured hardening resin P may be arranged on the transparent base S by other method. For example, the transparent base S previously coated with the uncured hardening resin P may be provided in the unwinding device  31 . Otherwise, it is possible that the surface of the forming roll  35 C is previously coated with the uncured hardening resin P, the resultant is pressed by the pressure roll  35 A, and thereby the uncured hardening resin P is in contact with the transparent base S. Otherwise, by providing a pool of the uncured hardening resin P by dropping the uncured hardening resin P in a cone-shaped region formed between the surface of the forming roll  35 C and the surface of the transparent base S, the transparent base S may be coated with the uncured hardening resin P. 
     In the foregoing embodiment and the like, the structure of the display apparatus  1  has been concretely described. However, it is not necessary to provide all layers. In addition, other layer (for example, reflective polarizing plate) may be provided. That is, various selections may be made according to the usage and the purpose. 
     Further, in the foregoing embodiment and the like, the active matrix type display apparatus  1  has been described. However, the invention can be applied to a simple matrix-driven display apparatus. 
     Further, in the foregoing embodiment and the like, the case that the illumination system  10  is an edge-light type has been described. However, the illumination system may be other type such as a subjacent type. Further, in the foregoing embodiment and the like, the liquid crystal display apparatus  1  has been described. However, it is needless to say that the invention can be applied to display apparatuses utilizing other principle. 
     It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alternations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.