Patent Publication Number: US-2006012739-A1

Title: Optical substrate, display device using the same, and their manufacturing methods

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an optical collective substrate used in a liquid crystal display device etc., and its manufacturing method. The invention also relates to a display device using the optical collective substrate and its manufacturing method.  
      2. Description of Related Art  
      A liquid crystal panel is disclosed that has a structure where a group of lenses is disposed between the backlight and display electrodes, and collects light from the backlight in the respective display electrodes on a pixel basis (for example, see Patent Reference 1).  
      [Patent Reference 1] 
      Japanese Patent Application Laid-Open No. 89025/90 (pages 2 to 3 and FIGS. 1 to 3)  
      In a liquid crystal panel described in this Reference, as a group of lenses mentioned above, a lens array plate is used where a large number of lenses based on high-refractive-index portions, convex sphere, etc. are formed in matrix on a transparent plate different from a liquid crystal panel substrate using, or the liquid crystal panel substrate itself has a lens array with the similar structure. By means of the lens array, light of the backlight that has been intercepted in an untransmissive portion around the display electrode is mostly collected to the display electrode, the light is intended to be used effectively, and the luminance of pixels is enhanced without increasing the driving power of the backlight.  
      However, in the prior art, a planoconvex lens with a spherical convex surface is used as a lens that collects light to the display electrode, i.e., pixel electrode. Therefore, chromatic aberration or the like is apt to occur in the transmitted light, which is not preferable, and particularly, may become a considerable problem for display devices that display color images.  
      In addition there is a tendency to place an excessive load on the manufacturing process for forming the convexity of the lens in an appropriate spherical surface. In particular, as miniaturization of the pixel is advanced due to a demand for high resolution of image, the size of a lens has to be reduced more and more, and so the prior art has disadvantages.  
      Furthermore, the liquid crystal display device or the like generally uses various optical elements or other structural elements in addition to the member or structure for the lens, and so the actual situation is that the so-called workability has to be taken into account in a combination of the lens member and the structural elements.  
     SUMMARY OF THE INVENTION  
      In view of the foregoing, an object of the present invention is to provide an optical collective substrate and a display device using it, which can make effective use of light while avoiding generation of chromatic aberration etc. in transmitted light.  
      Another object of the present invention is to provide an optical collective substrate and a display device using it, which can make effective use of light and can be simply manufactured.  
      Still another object of the present invention is to provide an optical collective substrate and a display device using it, which achieves high workability in a combination with other structural elements.  
      A further object of the present invention is to provide methods of manufacturing such optical collective substrates and display devices.  
      In order to achieve the above objects, an optical collective substrate according to an aspect of the present invention is an optical collective substrate of an optically transmissive material having a structure in which incident light from one principal plane side of the substrate is locally collected in each place toward an array of light-utilizable areas formed on the outside of the other principal plane, wherein the one principal plane is provided with a groove comprising an outline having at least one inclined plane associated with the light-utilizable area, the groove being filled with optically transmissive stuff of a predetermined refractive index, the filled groove portions making bases for allowing the incident light from the one principal plane side to be collected to the respective light-utilizable areas.  
      According to this aspect, the incident light is collected to the respective light-utilizable areas using the groove portions filled with the optically transmissive stuff, instead of using the spherical lens, whereby chromatic aberration etc. caused by the spherical lens hardly occur in the collected light, and it is possible to use appropriate light with ease and with high efficiency for color display. Further, since it is only required to form the groove on one principal plane of the optical collective substrate, this structure does not need conventional complicated processes for forming a spherical lens and thus is simple. In particular, this structure is advantageous to display devices that handle fine pixels. Furthermore, since the groove is formed on the side (one principal plane of the optical collective substrate) on which the light is incident, and is not formed on the side (the other principal plane) on which the light-utilizable areas are arranged, the other principal plane can be used with the plane kept flat or unprocessed when the optical collective substrate is used, for example, as a back substrate of a typical liquid crystal display device, resulting in an advantage of making it easy to form on the other principal plane other structural elements, such as thin-film transistors (TFTs) for driving pixels, required for the display device. In addition to this advantage, the optically transmissive stuff used for filling the grooves is readily formed to have a height equal to a height of the portions other than the groove in the one principal plane, whereby it is thus possible to maintain a high degree of flatness even in the one principal plane of the optical collective substrate, and it is easy to paste other structural elements, for instance, polarizing plate to the plane or the like. This structure thus exhibits high workability.  
      In this aspect, the groove may extend along at least a part of an edge of the light-utilizable area. It is thereby possible to form the groove with a simple pattern.  
      Moreover, it is preferable that the one principal plane has planes extending with a substantially equal height in areas other than the groove. In this way, since the planes have the height equal to one another, it is also possible to achieve effective pasting of other structural elements as described above in the one principal plane of the optical collective substrate.  
      Further in this aspect, the optically transmissive stuff may have a function of pasting an additional film to the one principal plane. In this way, the optically transmissive stuff also servers as an adhesive in forming the additional film, i.e., another structural element on the one principal plane of the optical collective substrate, thereby providing extreme convenience in manufacturing.  
      In order to achieve the above objects, a display device according to another aspect of the present invention is a display device using an optical collective substrate described above, comprising a display medium for forming images, which is disposed on the other principal plane side and carried on the optical collective substrate, the display device having pixels or predetermined displayed units corresponding to the light-utilizable areas.  
      According to this aspect, since light is collected to pixels or predetermined displayed units of the medium for forming images in the display device, it is possible to make each of the pixels or predetermined displayed units bright and to display clear images on the whole. Further, this aspect preferably leads to mitigation of the above-mentioned problem about chromatic aberration etc. Furthermore, since the other principal plane side of the optical collective substrate is flat or unprocessed, it is easy to form other structural elements required for the display device, thus providing convenience. When an additional film is pasted to the one principal plane by the optically transmissive stuff, since it is possible to eliminate an adhesive that has been conventionally prepared separately for pasting an additional film such as an optical film to the substrate, the processes are simplified. The structure of the display device is applicable to a liquid crystal display device using a liquid crystal medium as a medium for forming displayed images, and is remarkably effective in covering a loss of light that is inevitable due to a polarizing plate or the like used in a general liquid crystal display device.  
      In order to achieve the above objects, a method of manufacturing an optical collective substrate according to still another aspect of the present invention is a method of manufacturing an optical collective substrate of an optically transmissive material having a structure in which incident light from one principal plane side of the substrate is locally collected in each place toward an array of light-utilizable areas formed on the outside of the other principal plane, comprising: a first step of forming, in the one principal plane, a groove comprising an outline having at least one inclined plane associated with the light-utilizable area; and a second step of filling the groove with optically transmissive stuff of a predetermined refractive index, and in addition to this, the optically transmissive stuff may have an adhesive property and the method may further comprise a third step of affixing an additional film on the one principal plane using the adhesive property of the optically transmissive stuff, or in addition to this, the second step may include a process of applying the optically transmissive stuff to the one principal plane of the optical collective substrate globally.  
      According to this aspect, it is possible to easily manufacture the optical collective substrate having the advantages described above. When the grooves are formed using a pattern along at least a part of the edges of the light-utilizable area, loads on manufacturing are greatly reduced, as compared with the conventional forming of the spherical lens. Furthermore, the first step may comprise a masking process of covering the one principal plane with a mask having a pattern that causes an area of a groove to be formed to be exposed and causes the other area to be masked and a spraying process of spraying the masked one principal plane of the optical collective substrate with a substance capable of etching the material of the optical collective substrate, and in the spraying process a spraying nozzle may be used to blast the substance capable of etching, positioned opposed to the area of the groove externally appearing from the mask, and moved along the extending pattern of the area of the groove while spraying the substance capable of etching in a condition that the nozzle is positioned at a center of the area of the groove in a direction traversing a moving direction of the nozzle, whereby the groove is formed with excellence.  
      In order to achieve the above objects, a method of manufacturing a display device according to still another aspect of the present invention is a method of manufacturing a display device using an optical collective substrate of an optically transmissive material having a structure in which incident light from one principal plane side of the substrate is locally collected in each place toward an array of light-utilizable areas formed on the outside of the other principal plane, wherein: the one principal plane is provided with a groove comprising an outline having at least one inclined plane associated with the light-utilizable area, the groove being filled with optically transmissive stuff of a predetermined refractive index, the filled groove portions making bases for allowing the incident light from the one principal plane side to be collected to the respective light-utilizable areas, the method of manufacturing comprising: a step of forming such a display mechanism construction including a display medium for forming an image on the other principal plane side of the optical collective substrate that the construction has pixels or predetermined displayed units corresponding to the light-utilizable areas, and furthermore, the method may further comprises a step of pasting an additional film to the one principal plane of the optical collective substrate, wherein an adhesion property of the optically transmissive stuff makes adhesion of the additional film. It is thereby possible to manufacture display devices capable of satisfactorily exhibiting the advantages described above. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a schematic plan view of a part of an optical collective substrate of one embodiment according to the present invention.  
       FIG. 2  is a schematic sectional view of a part of an optical collective substrate, taken along a line II-II of  FIG. 1 .  
       FIG. 3  is a perspective view of a part of the optical collective substrate of  FIGS. 1 and 2 .  
       FIG. 4  is a sectional view showing a general construction of a part of a transmissive liquid crystal display device using the optical collective substrate of  FIGS. 1-3 .  
       FIG. 5  is a schematic plan view showing a combinational form of a TFT-composite layer and a black matrix in a liquid crystal display device of  FIG. 4 .  
       FIG. 6  is a schematic sectional view showing an actual form of adhesion of a film to an optical collective substrate in the invention.  
       FIG. 7  is a partial sectional view showing a general construction of a reflective liquid crystal display device using an optical collective substrate according to the invention.  
       FIG. 8  is a partial sectional view showing a general construction of a transflective liquid crystal display device using an optical collective substrate according to the invention.  
       FIG. 9  is a schematic plan view showing a construction of a pixel electrode used in a liquid crystal display device of  FIG. 8 .  
       FIG. 10  is a schematic sectional view of a part of an optical collective substrate of the other embodiment according to the invention.  
       FIG. 11  is a schematic sectional view of a part of an optical collective substrate of a further embodiment according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT(S)  
      The aforementioned aspects and other embodiments of the present invention will now be described in more detail with reference to accompanying drawings.  
       FIG. 1  shows a view in which one principal plane of an optical collective substrate according to one embodiment of the present invention is taken from its front side.  FIG. 2  shows a sectional structure of the optical collective substrate, taken along a line II-II of  FIG. 1 .  FIG. 3  is a view in which a part of the optical collective substrate is taken obliquely.  
      An optical collective substrate  20  consists of an optically transmissive material such as glass and formed in the shape of a flat plate with one principal plane  21  having an area covering a predetermined display area and the other principal plane  22  on the opposite side to the plane  21 . As in the conventional technique, the optical collective substrate  20  has a function of collecting incident light Li from the one principal plane  21  side locally in each place toward an array of light-utilizable areas  201  (described later) formed on the outside of the other principal plane  22 . However, in the optical collective substrate  20  in this embodiment, instead of a spherical structure, V-shaped grooves  2   v  are formed on the one principal plane  21  in association with the light-utilizable areas  201 . More specifically, each of the grooves  2   v  is comprised of an inclined surface  2   v   0  slanted to one of the light-utilizable areas  201  and an inclined surface  2   v   1  slanted to another (adjacent) light-utilizable area  201 . The V-shaped groove  2   v  is filled with optically transmissive stuff  2   m  of a predetermined refractive index different from that of the substrate body (which is preferably smaller than that of the substrate body), and the filled groove portions  2 V make bases for allowing the incident light Li from the one principal plane  21  side to be collected to the respective light-utilizable areas  201  as transmitted light Lo shown in  FIG. 2 .  
      The array of the light-utilizable areas  201  herein refers to areas requiring light collection in a display device disposed on the other principal plane  22  side to be applied. A specific example will be described later. The V-shaped groove  2   v  is formed in association with the light-utilizable areas  201  so that the V-shaped groove portions  2 V collect the light to the light-utilizable area  201 , and on the other hand, can be practically formed in locations opposite to areas  202  that do not utilize light. In the plan view of  FIG. 1 , light-utilizable areas  201  are indicated schematically by alternate long and short dashed lines in superposition.  
      The V-shaped groove  2   v  extends along at least a part of an edge of the light-utilizable area  201 , in this example, in form of surrounding the area  201 . Accordingly, it is possible to pattern the V-shaped groove  2   v  with ease without complicated optical consideration. The V-shaped groove  2   v  has a pair of inclined surfaces that form the V-shaped outline in the sectional view, and the one principal plane  21  of the optical collective substrate  20  has a plurality of flat surfaces  2   p  (corresponding to a cross-hatching area in  FIG. 1 , and other flat surfaces are the same) extending with a substantially equal height in areas other than the inclined surfaces, i.e., other than the V-shaped groove portions  2 V.  
      Optically transmissive stuff  2   m  as a filler may be a material having an adhesion property such as viscous or adhesive materials, e.g. a mixture of acrylic ester copolymer and polyurethane resin. According to the adhesion property, it is convenience to bring an additional film such as other optical films into intimate contact with the one principal plane  21  of the optical collective substrate  20 . A photosetting resin may also be used as a material for the optically transmissive stuff  2   m.    
      In thus structured optical collective substrate  20 , instead of using spherical lenses, using the V-shaped groove portions  2 V each of which is filled with optically transmissive stuff  2   m  and has flat inclined surfaces as interfaces for refraction of light, the incident light is collected toward each of the light-utilizable areas  201 . Therefore, the collected light L o is hardly subjected to chromatic aberration or the like that may be generated when a spherical surface of the spherical lens is used as an interface of light refraction, and it is possible to use appropriate light with ease and with high efficiency for color display. Furthermore, since it is only required to form the V-shaped groove  2   v  comprised of two flat inclined surfaces on the one principal plane  21  of the optical collective substrate  20 , it results in advantageous aspect of processing with a high degree of precision and results in simplified processes. This feature is advantageous especially for display devices that handle fine pixels.  
       FIG. 4  shows an example of a transmissive type liquid crystal display device constructed using the optical collective substrate  20 .  
      In  FIG. 4 , the optical collective substrate  20  is used as a back substrate that carries a liquid crystal medium  40  together with a front substrate  60 . The one principal plane  21  of the optical collective substrate  20  is situated on the outside of the display device, while the other principal plane  22  is situated on the inside of the display device.  
      The optical collective substrate  20  is provided on its outside with a polarizing plate  10 , while being provided on its inside with a TFT-composite layer  30 . The front substrate  60  is provided on its outside with another polarizing plate  70 , while being provided on its inside with a color filter  50 .  
      It is noted that various other films and layers specific to a liquid crystal display device may be formed in addition to those described above, but will be omitted as long as a note is not given for the sake of clarity of description.  
      As shown in  FIG. 4 , the color filter  50  is provided with a black matrix  5   b  for masking an area in which a pixel is not formed against the display surface side. A non-shield areas  5   d  where a layer of the black matrix  5   b  are not formed is occupied by a coloring layer  5   c , and the optical collective substrate  20  is applied and incorporated using the non-shield areas  5   d  as the light-utilizable areas  201  described above.  
      The non-shield area  5   d  of the black matrix  5   b  will be described specifically below with reference to  FIG. 5 .  
       FIG. 5  shows a plan view in which the black matrix  5   b  for a pixel, and the thin-film transistor (TFT)  31  and a pixel electrode  3 P for a pixel in the TFT-composite layer  30  are overlaid on each other.  
      The TFT  31  basically has a gate electrode  3   g  drawn from a gate bus line  3 G, a semiconductor layer  3   c  deposited on the electrode  3   g  via a gate insulating film not shown, a drain electrode  3   d  in contact with the semiconductor layer  3   c  from one side of the layer  3   c , and a source electrode  3   s  that is in contact with the layer  3   c  from the other side of the layer  3   c  and is drawn from a source bus line  3 S. The drain electrode  3   d  extends in the direction opposite to the source electrode  3   s , and connects to the pixel electrode  3 P consisting of a transparent conductive material such as ITO (Indium Tin Oxide). With the TFT  31 , voltage corresponding to pixel information is supplied to the pixel electrode  3 P via the drain electrode  3   d , and the pixel electrode  3 P applies the voltage locally in that area to a portion of the liquid crystal medium  40  facing to the electrode  3 P.  
      As indicated by bold lines in  FIG. 5 , the black matrix  5   b  is formed to mask the bus lines  3 S and  3 G, the entire TFT  31  and an outer edge of the pixel electrode  3 P. Accordingly, setting the area (non-shield area)  5   d  indicated by oblique lines in  FIG. 5  as the light-utilizable area  201  achieves the advantages specific to the optical collective substrate  20  as described above. It is noted that, as can be seen from  FIG. 5 , the non-shield area  5   d  is not a perfect rectangle because the TFT  31  exists. However, with the area  5   d  assumed to approximately have a rectangle-shaped form, a pattern of the V-shaped groove portion  2 V cab be specified. The alternate long and short dashed lines in  FIG. 5  indicate a position of a center or back end portion, i.e., a bottom portion of the V-shaped groove  2   v  of the optical collective substrate  20 . In this embodiment, the bottom position is located in a center in the traversing direction of a pattern of the black matrix  5   b.    
      In this embodiment, the light-utilizable area  201  is set to the non-shield area  5   d  of the black mask layer, but may be an area of the pixel electrode  3 P formed in the TFT-composite layer  30 . In addition, in a top-gate type TFT structure, instead of the so-called bottom-gate type TFT structure, a light shield film is generally provided in an underlayer portion of the TFT-composite layer so that light from the backlight does not enter a semiconductor layer of the TFT, and an area that is not shielded by the shield film can be used as a light-utilizable area  201 . In any cases, a liquid crystal display device is constructed so that a pixel structure is formed in relation to (association with) the light-utilizable area  201 . It is noted that the embodiment takes a form in which one light-utilizable area corresponds to one pixel area (implying an area substantially considered to be a pixel area), but one light-utilizable area may be a predetermined displayed unit, i.e., two or more pixel areas, or sub-areas that are divisional portions of one pixel area.  
      The V-shaped groove  2   v  is formed on the side  21  on which light is incident, and is not formed on the side  22  on which the light-utilizable areas  201  are arranged. Therefore, in the liquid crystal display device using the optical collective substrate  20  as a back substrate, the other principal plane  22  can be used with the plane  22  kept flat or unprocessed. Accordingly, there is an advantage that the principal plane  22  is easy to form structural elements such as TFTs  31  and pixel electrodes  3 P thereon.  
      As shown in  FIG. 2 , it is also easy to make the height of optically transmissive stuff  2   m  with which the V-shaped groove  2   v  is filled equal to the height in portions other than the V-shaped grooves  2   v  of the principal plane  21  to form a flat surface as a whole. The flat principal plane  21  enhances the adhesion of other structural elements such as the polarizing plate  10  to the plane  21 . Further, the principal plane  21  of the optical collective substrate  20  has flat planes  2   p  with the same height except the V-shaped groove portions  2 V, and thus is advantageous for tighter pasting. As an additional remark, since the V-shaped groove  2   v  is filled with optically transmissive stuff  2   m  that is not air, a film affixed to the principal plane  21  is hard to remove.  
      Thus, in the liquid crystal display device, the light from the backlight departs from originally light-shielded areas and is collected toward pixels or predetermined displayed units as light-utilizable areas. Accordingly, it is possible to make each of the pixels or redetermined displayed units bright and to display clear images on the entire display screen. Furthermore, the problem of the chromatic aberration or the like as mentioned above can be mitigated to implement excellent color display.  
      Moreover, the optically transmissive stuff  2   m  with the adhesion property is convenient for pasting the polarizing plate  10  to the substrate.  
      Herein, as a simple estimation, a comparison will be described below between a case of using an ordinary transparent substrate without the light-collecting function as a back substrate in a liquid crystal display device and a case of using the optically collective substrate  20  of this embodiment as the same.  
      When the liquid crystal layer  40  is fixed to a predetermined optical modulation state and it is assumed that the transmittance of the polarizing plates  10  and  70  is Tp, the transmittance of the color filter  50  is Tc, and an aperture ratio (a ratio of the effective area of all the non-shield areas to the effective area of all the display areas) is AR, transmittance T of the apparatus in the former case is approximately calculated as follows. 
 
T≈Tp×Tc×AR≈50%×33%×0.6 ≈10% 
 
      On the contrary, when considered AR=1.0 due to the light-collecting function of the optical collective substrate  20 , transmittance T of the apparatus in the latter case under the same conditions is approximately calculated as follows. 
 
T≈Tp×Tc×AR≈50%×33%×1.0≈17% 
 
      Accordingly, the latter case, i.e., this embodiment increases the luminance approximately 1.7 times as much.  
      In this way, even when a loss of light is occurred in the polarizing plates  10  and  70 , it is possible to increase the luminance in the entire display device. Since the polarizing plates are required be used in most of liquid crystal display devices, this structure is significantly useful.  
      It is preferable to set the groove portions  2 V of the optical collective substrate  20  for optimal specifications as appropriate in accordance with an applied display device. For example, when it is assumed that vertical and horizontal sizes of the light-utilizable area are respectively a and b (see  FIG. 1 ), the refractive index of the optically transmissive stuff  2   m  is n 1 , the refractive index of the main body of the optical collective substrate  20  is n 2 , the width of the shield area  5   b  is 2x, the distance from the groove portion  2 V to the substrate  20  is y, and the height of the groove  2   v  is z (see  FIG. 4 ), an excellent result was obtained under conditions that a=300 μm, b=100 μm, n 1 =1.3, n 2 =1.5, 2x= 20  μm, y=400 μm, and z=2 μm. It is noted that air can be used as a substitute for the optically transmissive stuff  2   m  , but excellent light-collecting function was not obtained in the case of the air. This is because in a structure where a V-shaped groove portion is disposed on the outside of the liquid crystal panel, the V-shaped groove portion consisting of the air tends to cause the light to spread excessively. As a further note, the reason for assuming the distance from the groove portion  2 V to the substrate  20  as y is: considering that a structural portion  3   b  (see  FIG. 4 ) such as a bus line and/or light shield film in which the light is not used practically exists under the shield member  5   b ; and that the light is collected getting away from the structural portion. Since the layers  30 ,  40  and  50  are generally formed to have an extremely thinner thickness than that of the substrate  20 , there is also a case of designing an optimal structure by assuming the distance from the groove portion  2 V to the shield member  5   b  as y even when such a structural portion exists.  
      The optical collective substrate  20  is manufactured as described below.  
      Basically carried out are:  
      (1) a first step of forming the V-shaped groove  2   v  on the one principal plane  21  in association with the light-utilizable areas  201 ; and  
      (2) a second step of filling the V-shaped groove  2   v  with the optically transmissive stuff  2   m  of a predetermined refractive index.  
      In the first step, a masking process is carried out, in which the one principal plane  21  is covered with a matrix-formed mask having a pattern that causes an area of the V-shaped groove  2   v  to be formed to be exposed and causes the other area to be masked. Then, a spraying process is carried out, in which the masked one principal plane  21  of the optical collective substrate  20  is sprayed with a substance capable of etching the material of the optical collective substrate  20 . In this example, the material of the optical collective substrate  20  is glass (SiO 2 ), and as the substance capable of etching for the glass, i.e., etchant, a hydrofluoric acid solution is blasted in mist state.  
      More specifically, in the spaying process, a spraying nozzle is used to blast the hydrofluoric acid solution. The spraying nozzle has a practical outlet face opposite to an area for the V-shaped groove unmasked in the matrix-formed mask, and is moved along the extending pattern for the area for the V-shaped groove. At the occasion of this preferably the solution blasted from the nozzle is sprayed in the form of a beam and the etchant is sprayed with the nozzle positioned at a center of the width of the V-shaped groove  2   v  in a direction traversing a moving direction of the nozzle. In this way, it is possible to position a bottom of the groove at the center of the width of the groove pattern with precision and to form a V-shaped cross-section appropriately.  
      When the optically transmissive stuff  2   m  is paste stuff such as, for example, a mixture of acrylic acid ester copolymer and polyurethane, the polarizing plate  10  can be pasted to the one principal plane  21  using the adhesion property of the optically transmissive stuff  2   m  in a third step. It should be noted that, instead of the polarizing plate, it may be possible to paste other various films and layers such as a protect film and a quarter-wave plate as needed in the applied system.  
      Further, in the second step, the filling step can be carried out by coating the whole surface of the one principal plane  21  of the optical collective substrate  20  with the optically transmissive stuff  2   m  in spin coating. Accordingly, as shown in  FIG. 6 , the optically transmissive stuff  2   m  is practically disposed on the flat plane  2   p , not only inside the V-shaped groove  2   v  but also.  
      Instead of using the paste stuff described above, a photosetting resin may be used as optically transmissive stuff  2   m . In this case, the resin in paste state is first applied to the V-shaped groove and the principal plane, the additional film is placed thereon, and then the light is applied from the opposite principal plane, whereby the resin is cured, the groove portion  2 V is formed, and the additional film adheres thereto.  
      In order to manufacture a liquid crystal display device using the optical collective substrate, there may be basically carried out a step of forming a construction including a display medium for forming an image on the other principal plane  22  side of the optical collective substrate  20  in such a manner that the construction has pixels or predetermined displayed units corresponding to the light-utilizable areas  201  (in the above embodiment, non-shield areas  5   d  in the layer of black matrix  5   b ) defined on the optical collective substrate  20 . The third step may be carried out at this occasion.  
      Although the specific example of the first step mentioned above depends on the so-called etching processing, the V-shaped groove  2   v  may be formed by scribing with a scriber, or may carry out a grinding process of grinding the principal plane with a grinder to form the groove.  
       FIG. 7  shows an example of a reflective liquid crystal display device constructed using the optical collective substrate, and portions similar to those in  FIG. 4  are assigned the same reference numerals as in  FIG. 4 .  
      In  FIG. 7 , an optical collective substrate  20 ′ is used as a front substrate, and one principal plane of the substrate is faced to the display surface side. A back substrate  80  is a typical substrate prepared for principally carrying a TFT composite layer  30 ′ or other layers. In the TFT composite layer  30 ′, a pixel electrode  3 P′ having a light reflective property is formed, and the pixel electrode  3 P′ has a function of reflecting the light incident from the front side as well as a function of locally applying the voltage to the liquid crystal layer  40 .  
      The optical collective substrate  20 ′ is also formed using the non-shield area  5   d  in the layer of black matrix  5   b  as the light-utilizable area  201 , but has a shorter distance from a V-shaped groove portion  2 V′ to the light-utilizable area than that in the case of  FIG. 4 , and thus has different conditions to collect the light from those in the case of  FIG. 4 . Accordingly, the optical collective substrate  20 ′ is formed to adapt to such different conditions. In other words, the inclination of the inclined surfaces of the V-shaped groove  2   v ′, the refractive index of the optically transmissive stuff  2   m ′ and so on are optimized in accordance with the conditions. Since the degree of narrowing the light is higher than that in the case of  FIG. 4 , the optimization is carried out basically by making the inclined surfaces of the V-shaped groove  2   v ′ steeper, and/or by decreasing the refractive index of the optical collective stuff  2   m′.    
      It is noted that other structural elements are also modified in property and structure to be adapted to the reflective liquid crystal display device, but descriptions thereof are omitted herein for the sake of clarity.  
       FIG. 8  shows an example of a transflective liquid crystal display device constructed using the optical collective substrate, and portions similar to those in  FIG. 4  are assigned the same reference symbols as in  FIG. 4 .  
      In  FIG. 8 , two optical collective substrates are used. One optical collective substrate  20 ″ is used as a back substrate, while the other optical collective substrate  20 ″′ is used as a front substrate. A principal plane of the optical collective substrate  20 ″ on which the V-shaped groove is formed is faced to the back side of the apparatus, while a principal plane of the optical collective substrate  20 ″′ on which the V-shaped groove is formed is faced to the display surface side of the apparatus. In a TFT-composite layer  30 ″, there is formed a pixel electrode  3 P″ comprised of a reflective electrode part  3 Pr of a light reflective property and a transmissive electrode part  3 Pt of a light transmissive property.  
      In this type of liquid crystal display device, external light incident from the front side is subjected to optical modulation corresponding to an image to be displayed and is reflected to lead to the front side, while incident light caused by the backlight from the back side is also subjected to optical modulation corresponding to an image to be displayed and is transmitted to lead to the front side. Then, efficiently displaying of images is achieved by mainly using the external light (ambient light) when the use environment is well-lighted (reflective mode), or by mainly using the light from the backlight when the use environment is dark (transmissive mode).  
      The pixel electrodes  3 P″ are formed to adapt to this type. For example, the electrodes  3 P″ can be formed in plane structure as shown in  FIG. 9 , and one pixel electrode  3 P″ is comprised of the transmissive electrode part  3 Pt located at the center and the reflective electrode part  3 Pr around the part  3 Pt. Accordingly, the pixel electrode  3 P″ performs local application of voltage to an area of the liquid crystal layer  40 , while the transmissive electrode part  3 Pt causes the incident light from the backlight to be passed through to the liquid crystal layer  40  at the center portion of the pixel area, and the reflective electrode part  3 Pr reflects the incident light from the front in an outer annular area surrounding the center portion (see  FIG. 8 ).  
      Accordingly, the optical collective substrate  20 ″ on the back side has a role of collecting the light from the backlight to the transmissive electrode part  3 Pt, while the optical collective substrate  20 ″′ on the front side has a role of collecting the light from the front side to the reflective electrode part  3 Pr. Therefore, in this embodiment, the light-utilizable area defined in the optical collective substrate  20 ″ is an area of the transmissive electrode part  3 Pt at the center, and the light-utilizable area defined in the optical collective substrate  20 ″′ is an area of the reflective electrode part  3 Pr in the outer area.  
      It is noted that, also in this case, distances from the V-shaped groove portions  2 V″ and  2 V″′ to the light-utilizable areas, and the conditions to collect the light are respectively different from those in the case of  FIG. 4 . Therefore, the optical collective substrates  20 ″ and  20 ″′ are respectively formed to adapt to the conditions.  
      As is suggested from the foregoing, since the optical collective substrate  20 ″ needs to greatly increase the degree of narrowing the light, the inclined surfaces of the V-shaped groove  2   v ″ are made greatly abrupt, or the refractive index of the optically transmissive stuff  2   m ″ is set at a smaller value. The optical collective substrate  20 ″′ needs to collect the light to the reflective electrode part  3 Pr occupying the outer area, and inclined surfaces of the V-shaped groove  2   v  ″′ and a refractive index of the optically transmissive stuff  2   m ″′ set accordingly.  
      Although this embodiment may also be modified in property and structure for other structural elements to adapt to the transflective liquid crystal display device, descriptions thereof are omitted herein for the sake of clarity.  
      In the above-mentioned embodiments, the groove formed on the optical collective substrate has a V-shaped outer outline symmetric with respect to a line on the sectional view. However, it may be modified in other various shapes.  
       FIG. 10  shows one modification, where an optical collective substrate  20 A uses a pair of modified V-shaped groove portions  2 AV 0  and  2 AV 1 , instead of the V-shaped groove portions as described above. The modified V-shaped groove portions  2 AV 0  and  2 AV 1  comprise: modified V-shaped grooves  2 Av 0  and  2 Av 1  each consisting of a pair of an inclined plane  2 Aq 0  or  2 Aq 1  formed on one principal plane  21 A of the optical collective substrate  20 A in association with the light-utilizable area and a perpendicular plane  2 Ap 0  or  2 Ap 1  formed perpendicularly on the one principal plane  21 A; and optically transmissive stuff  2 Am 0  and  2 Am 1  of a predetermined refractive index buried in the modified V-shaped grooves, respectively.  
      Also in such groove portions, the interface for mainly refracting the light is flat, so that the incident light from the one principal plane  21 A side can be collected toward the light-utilizable areas without generation of chromatic aberration etc. Incidentally, the first inclined plane  2 Aq 0  refracts the light toward one light-utilizable area, whereas the second inclined plane  2 Aq 1  refracts the light toward another light-utilizable area adjacent to the one light-utilizable area.  
      In addition, it may be possible to make construction by combining the V-shaped groove as shown in  FIG. 2  and the modified V-shaped groove as appropriate.  
       FIG. 11  shows another modification, where an optical collective substrate  20 B uses a trapezoid groove portion  2 BV, instead of the groove portions as described above. The trapezoid groove portion  2 BV comprises: a trapezoidal groove  2 Bv consisting of inclined planes  2 Bq 0  and  2 Bq 1  formed on one principal plane  21 B of the optical collective substrate  20 B in association with light-utilizable areas and a bottom surface  2 Bb that is substantially parallel to the one principal plane and that extends between the inclined planes; and optically transmissive stuff  2 Bm of a predetermined refractive index buried in the trapezoid groove.  
      Also in such a groove portion, the interface for mainly refracting the light is flat, so that the incident light from the one principal plane  21 B side can be collected toward the light-utilizable areas without generation of chromatic aberration etc. Incidentally, the first inclined plane  2 Bq 0  refracts the light toward one light-utilizable area, whereas the second inclined plane  2 Bq 1  refracts the light toward another light-utilizable area adjacent to the one light-utilizable area.  
      In addition, it may be possible to make construction not only by combining the V-shaped groove as shown in  FIG. 2  and the trapezoid groove as appropriate, but also by adding the form of the modified V-shaped groove as shown in  FIG. 10  as appropriate.  
      Basically, it is possible to apply the manufacturing methods as described above to such modifications.  
      Although some embodiments are described above, the present invention is not limited to them but may be modified in other various forms. For instance, the optical collective substrates according to the present invention are not necessarily limited in application to liquid crystal display devices. They are basically applicable to any display devices that define an array of light-utilizable areas to which the light is collected as described above.  
      For the description, the embodiments are intended to have a color filter provided with a black matrix, but the present invention is not restricted to such an intention, and it is apparent to be able to apply the invention to a constitution in which another structural element is provided with a black matrix or the equivalent means, or to a constitution in which no black matrix exists.  
      As in the above, the preferable embodiments described herein are illustrative and not restrictive. The scope of the invention is indicated by the appended claims, and all variations that come within meanings of the claims are intended to be embraced in the present invention.  
     LIST OF REFERENCE SYMBOLS  
     
         
           10  . . . polarizing plate  
           20 ,  20 ′,  20 ″,  20 ′″,  20 A,  20 B . . . optical collective substrate  
           21 ,  21 A,  21 B . . . one principal plane  
           22 ,  22 A,  22 B . . . the other principal plane  
           2   v ,  2   v ′,  2   v ″,  2   v ′″ . . . V-shaped groove  
           2 Av 1 ,  2 AV 0  . . . modified V-shaped groove  
           2 Bv . . . trapezoid groove  
           2   m ,  2   m ′,  2   m ″,  2   m ′″,  2 Am 0 , 2 Am 1 ,  2 Bm . . . optically transmissive stuff  
           2 V,  2 V′,  2 V″,  2 V′″ . . . V-shaped groove portion  
           2 AV 0 ,  2 AV 1  . . . . modified V-shaped groove portion  
           2 BV . . . trapezoid groove portion  
           2 AP 0 ,  2 Ap 1 , . . . perpendicular plane  
           2 Aq 0 ,  2 Aq 1 ,  2 Bq 0 ,  2 Bq 1  . . . inclined plane  
           2 Bb . . . bottom surface  
           2   p  . . . flat surface  
           2   v   0 ,  2   v   1 , . . . inclined surface  
           201  . . . light-utilizable area  
           202  . . . light-unutilizable area  
           30 ,  30 ′,  30 ″ . . . TFT-composite layer  
           31  . . . TFT  
           3 S . . . source bus line  
           3 G . . . gate bus line  
           3 P,  3 P′,  3 P″ . . . pixel electrode  
           3 Pr . . . reflective electrode part  
           3 Pt . . . transmissive electode part  
           40  . . . liquid crystal layer  
           50  . . . color filter  
           5   c  . . . coloring layer  
           5   b  . . . black matrix (shield area)  
           5   d  . . . non-shield area  
           60  . . . transparent substrate  
           70  . . . polarizing plate