Abstract:
A display apparatus includes a plurality of first electrodes, a second electrode facing the plurality of first electrodes, and a plurality of microcapsules. Each of the plurality of first electrodes corresponds to one of a color. The plurality of microcapsules have a dispersion media and a plurality of particles sealed therein and are disposed between the plurality of first electrodes and the second electrode. A microcapsule of the plurality of microcapsules providing one of the colors is arranged on the first electrode that corresponds to the one of the colors.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a continuation of pending U.S. application Ser. No. 11/448,057 filed Jun. 7, 2006 which is a divisional application of U.S. application Ser. No. 10/434,240 filed on May 9, 2003 (now U.S. Pat. No. 7,199,781), which is a continuation of U.S. application Ser. No. 09/673,372 filed on Oct. 16, 2000 (now U.S. Pat. No. 6,583,780), which is a U.S. National Stage of PCT/JP00/00976 filed Feb. 21, 2000, the contents of which are incorporated herein by reference in their entireties. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to a display panel using microcapsules which accommodates an electrophoretic or magnetophoretic particles, and more particularly, to a method of producing the display panel capable of arranging the microcapsules at a predetermined position on electrodes accurately and the display panel in which the microcapsules is accurately, arranged at the predetermined position on the electrodes. 
         [0003]    In an electrophoretic display apparatus and magnetophoretic display apparatus for displaying a desired picture by using the microcapsules, each sealing colored dispersion media and the electrophoretic particles, the uniform arrangement of the microcapsules over a substrate is important on a stable display operation. 
         [0004]    Conventionally, many methods with an object of producing a pressure sensing paper and a heat sensitive paper are proposed as methods of uniformly coating microcapsules on a plane surface. 
         [0005]    For instance, the Japanese Patent No. 1545227 discloses a method for producing a pressure sensing copying paper by a free fall vertical curtain method as a preferable method than an air knife or blade coating method. 
         [0006]    Also, the Japanese Patent No. 1376224 discloses a hopper typed coating apparatus as a similar method. 
         [0007]    Further, the Japanese unexamined patent publication No. 57-27172 discloses a method to spray microcapsules coating liquid to a web (a support body) which runs continuously and to obtain a coating layer of continuous constant thickness by leveling this with a leveling device. 
         [0008]    Moreover, the Japanese unexamined patent publication No. 62-138284 discloses a method in which a bonding layer is formed over a substrate, microcapsules layer is formed thereon, and the non-contacted microcapsules with the bonding layer are separated by gravity to form an uniform microcapsules layer of a single layer. 
         [0009]    However, the aforementioned methods are for the purpose of obtaining the uniform layer of microcapsules, and are not sufficient methods for forming the microcapsules layer used in the display panel. 
         [0010]    Properly placing the microcapsules at positions corresponding to electrodes or magnetic poles, configuring a display pixel in the display panel, is important to display a high definition image with uniform for each pixel. The display panel must form a uniform microcapsules layer and also control an arrangement place of each microcapsules. 
         [0011]    Particularly, when trying to display in colors, it is necessary to place a number of microcapsules of different display colors for each pixel and control each individually. To carry out such control, the microcapsules of each display color has to be placed selectively, accurately, and with high precision, the arrangement of the microcapsules must be carried out at a higher precision. 
         [0012]    At this point, a method of placing the microcapsules at a desired position selectively and accurately is not proposed in any method as aforementioned, and no such method exists except herein. 
       SUMMARY 
       [0013]    An object of the present invention is to provide a method of producing display panel using electrophoretic or magnetophoretic phenomenon, capable of placing microcapsules at the desired positions selectively and accurately. 
         [0014]    Another object of the present invention is to provide a method of producing a display panel by using electrophoretic or magnetophoretic phenomenon, capable of high definition display or full color display by placing microcapsules at the desired position selectively and accurately. 
         [0015]    Still, another object of the present invention is to provide a display panel using electrophoretic or magnetophoretic phenomenon, in which microcapsules are selectively and accurately placed at the desired positions. 
         [0016]    Therefore, a method of producing a display panel according to the present invention, in which microcapsules each sealing dispersion media of each colored to a predetermined color and electrophoretic or magnetophoretic particles are placed over a substrate, and the desired image is displayed by changing a representation color of the microcapsules by applying an electric field or magnetic field to each microcapsules, comprises: a step of coating the microcapsules, each sealing dispersion media of each colored to a predetermined color and an electrophoretic particle or magnetophoretic particle, onto a substrate by using an optical hardening resin as a binder material; a step of fixing the microcapsules at the desired areas onto the substrate on which the microcapsules are arranged by irradiating light beam on the areas to harden the binder material and to fix the microcapsules over the substrate, and; a step of removing the non-use microcapsules and the binder material except for the hardened binder material and microcapsules fixed onto the substrate. 
         [0017]    Preferably, electrodes poles or magnetic poles by which an electric field or magnetic field is applied to the microcapsules are provided over the substrate, in the step of fixing the microcapsules onto the substrate, the light beam is selectively irradiated to the areas corresponding to the electrodes or magnetic poles over the substrate to fix the microcapsules to every area corresponding to the electrodes or magnetic poles provided over the substrate. 
         [0018]    Further, in the step of the microcapsules fixed over the substrate, the light beam is selectively irradiated at the desired areas by using a photomask. 
         [0019]    Specifically, the processes is the steps are sequentially performed on the three types of microcapsules in which the electrophoretic particles or magnetophoretic particles each colored by one of three primary colors, and the dispersion media each colored by a color different to the three primary colors are sealed, and the three types of microcapsules being classified by the colors of the dispersion media, to arrange the three types of microcapsules over the substrate in a predetermined arrangement, to thereby produce the display panel able to display color images. 
         [0020]    Further, the processes is the steps are sequentially performed on the three types of microcapsules in which the dispersion media each colored by one of three primary colors, and the electrophoretic particles or magnetophoretic particles each colored by a color different to the three primary colors are sealed, and the three types of microcapsules being classified by the colors of the electrophoretic particles or magnetophoretic particles, to arrange the three types of microcapsules over the substrate in a predetermined arrangement, to thereby produce the display panel able to display color images. 
         [0021]    Further, the display panel, according to the present invention, in which microcapsules each sealing dispersion media of each colored to a predetermined color, and electrophoretic particles or magnetophoretic particles, are placed over a substrate, and a display is performed by applying an electric or magnetic field to each microcapsules, to change a presentation color of the microcapsule comprising: a pair of substrates, at least one being a transparent substrate; a plurality of microcapsules placed and fixed between the pair of substrates by an optical hardening resin binder; and electrodes or magnetic poles, provided over the substrate, for applying an electric or magnetic field to the microcapsules. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    Objects and features of the present invention as mentioned above becomes more clear from the following descriptions referring to the attached drawings, 
           [0023]      FIG. 1A  to  FIG. 1C  are diagrams for explaining a production method of a display panel of a first embodiment in the present invention; 
           [0024]      FIG. 1A  is a diagram showing a state of coating the microcapsules onto a substrate; 
           [0025]      FIG. 1B  is a diagram showing an irradiating of a light beam at the desired locations to be placed the microcapsules; 
           [0026]      FIG. 1C  is a diagram showing the removal of the microcapsules coated from a portion where the microcapsules should not be coated; by washing in water and;  FIG. 2A  and  FIG. 2B  are diagrams showing a structure of a display panel of a second embodiment in the present invention; 
           [0027]      FIG. 2A  is a sectional view showing a structure of the display panel; 
           [0028]      FIG. 2B  is an upper view of the display panel showing an arrangement of the microcapsules; 
           [0029]      FIG. 3A  to  FIG. 3C  are diagrams showing structures of three types of microcapsules; 
           [0030]      FIG. 3A  is a diagram showing microcapsules including dispersion media of magenta (M); 
           [0031]      FIG. 3B  is a diagram showing microcapsules including dispersion media of yellow (Y); 
           [0032]      FIG. 3C  is a diagram showing microcapsules including dispersion media of cyan (C); 
           [0033]      FIG. 4A  to  FIG. 4B  are diagrams showing states at the time that an electric field is applied to the microcapsules including dispersion media of magenta (M) shown in  FIG. 3A  from outside; 
           [0034]      FIG. 4A  is a diagram showing an inner state of the microcapsules when the electric field is applied from the lower to the upper direction; 
           [0035]      FIG. 4B  is a diagram showing an inner state of the microcapsules when the electric filed is applied from the upper to the lower direction; 
           [0036]      FIG. 5  is a diagram for explaining a production method of a display panel of a second embodiment in the present invention; 
           [0037]      FIG. 5A  is a diagram showing a state of coating the microcapsules over the substrate; 
           [0038]      FIG. 5B  is a diagram showing a step of irradiating of the light beam to the locations desired to place the microcapsules; 
           [0039]      FIG. 5C  is a diagram showing a state of removing the microcapsules coated at the portion not placing the microcapsules by washing in water; and 
           [0040]      FIG. 5D  is a diagram showing a state in which several types of microcapsules are finally placed over the substrate by repeating the steps of  FIG. 5A  to  FIG. 5C . 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
       [0041]    First, a method which is a basic production method of the display panel for the present invention and a method for placing the microcapsules at any positions over a substrate selectively and accurately will be explained referring to  FIGS. 1A to 1C  as a first embodiment of the present invention. 
         [0042]      FIGS. 1A to 1C  are diagrams showing a step of placing the microcapsules at the desired position over a substrate. 
         [0043]    At first, as shown in  FIG. 1A , microcapsules  43  are uniformly coated over a substrate  41  on which electrodes  42  are formed by using an optical hardening resin as a binder material  44 . 
         [0044]    Next, as shown in  FIG. 1B , the binder material  44  is hardened by selectively irradiating light beam at the only portions desired to place the microcapsules  43  over the substrate  41  by using a photomask  45 . 
         [0045]    And the binder material  44  on a portion not hardened is removed by washing in water. 
         [0046]    As a result, the microcapsules can be selectively and accurately placed at the only desired positions as shown in  FIG. 1C . 
         [0047]    In this way, in the production method, the microcapsules can be placed at the desired portions by only irradiating the light beam. Therefore, for instance, in a step of coating the microcapsules over the substrate  41 , a special high accuracy position control is not necessary, and the microcapsules can be selectively, accurately and easily placed at the desired positions. 
       Second Embodiment 
       [0048]    Next, the production method of the electrophoretic display panel being capable of the full color display for each pixel will be explained referring to  FIGS. 2A to 5D  as a second embodiment. 
         [0049]    First, a structure of the display panel is explained. 
         [0050]      FIGS. 2A to 2B  show structures of the display panel,  FIG. 2A  is a sectional view showing the structure of the display panel, and  FIG. 2B  is an upper view of the display panel showing an arrangement of the microcapsules. 
         [0051]    As shown in  FIG. 2A , the structure of a display panel  10  of the present embodiment has a structure in which a lower substrate  11  on which a first electrode  12  is formed and an upper substrate  14  on which a second electrode  13  is formed are placed so as to face the electrodes and three types of microcapsules  21 ,  22 , and  23  in which the dispersion media of each colored to magnetic (M), yellow (Y), and cyan (C) are placed in a predetermined arrangement therebetween. 
         [0052]    Note that the second electrode  13  and the upper substrate  14  side in the display panel  10  are a display surface. 
         [0053]    The three types of microcapsules  21 (M),  22 (Y), and  23 (C) are in two dimensional arrangement, orderly placed in a column direction and row direction, and are a stripe arrangement such that each two rows of the same color are sequentially repeated in the column direction continuously and the same color is continued in the row direction as shown in  FIG. 2B . The three types of microcapsules  21 (M),  22 (Y), and  23 (C) are placed on the lower substrate  11 . 
         [0054]    The lower substrate  11  is a substrate which is configured by any insulation members supporting the display panel  10 . 
         [0055]    The first electrode  12 , as shown in  FIG. 2B , is a divisional electrode formed so as to be individually applicable a desired electric field to each of a set of microcapsules of each two microcapsules with the same color which is continuously placed in the column direction, and is formed over the lower substrate  11 . A switch element in the first electrode  12  of the display panel  10  in the present invention is provided for each electrode corresponding to each set of microcapsules, thereby a selection signal is applied for each column from a not shown matrix driving circuit. Further a control signal and outputs from a driving transistor are applied to each row, and the desired electric field is applied to a desired set of microcapsules. 
         [0056]    A charged pigment particles is mixed and dispersed in the dispersion media in which each of the microcapsules  21 ,  22 , and  23  is colored to the predetermined color as aforementioned mentioned above. The microcapsules  21 ,  22 , and  23  are individually housed in the microcapsules. The display panel  10  of the present embodiment reproduces color by a subtractive color and mixture method and each dispersion media is respectively dyed to three types of cyan (C), magenta (M), and yellow (Y) as aforementioned above. Also, a charge pigment particles is dyed to white. 
         [0057]    A structure of each of the three types of microcapsules is shown in  FIGS. 3A to 3C . 
         [0058]      FIG. 3A  is a diagram showing the microcapsules  21  of magenta (M) and shows a state in which a white pigment particles  27  is dispersed in dispersion media  24  dyed by magenta. 
         [0059]      FIG. 3B  is a diagram showing microcapsules  22  of yellow (Y) and shows a state in which the white pigment particles  27  is dispersed in a dispersion media  25  dyed by yellow. 
         [0060]    Also,  FIG. 3C  is a diagram showing microcapsules  23  of cyan (C) and shows a state in which the white pigment particles  27  is dispersed in a dispersion media  26  dyed by cyan. 
         [0061]    A state when the electric field from outside is being applied to such the microcapsules will be explained as an example of the microcapsules  21  of magenta referring to  FIGS. 4A and 4B . 
         [0062]    If it is assumed that the white pigment particles  27  is charged to negative and an electric field E is applied to the microcapsules  21  in a direction as shown in  FIG. 4A , the white pigment particles  27  charged to negative migrates to the under side and the white pigment particles  27  is concentrately distributed to the lower. As a result, when the microcapsules  21  are seen from above, color of dispersion media  24  dyed by magenta, i.e. magenta is observed. 
         [0063]    In contrast, if an electric field E in a direction as shown in  FIG. 4B  is applied to this microcapsules  21 , the white pigment particles  27  migrates to the upper side and the white pigment particles  27  is concentrately distributed to the upper, thereby white is observed when this microcapsules  21  is seen from above. 
         [0064]    As shown in the figure, the microcapsules is placed on each electrode of the first electrode  12  formed over the lower substrate  11  being divided and microcapsules layer is formed. Note that each microcapsules is fixed between the first electrode  12  and the second electrode  13  by the binder material  15  at this time. 
         [0065]    And an electric field applied to each microcapsules is controlled by the first electrode  12  and each microcapsules provides the color of the dispersion media or white. 
         [0066]    Also, in the display panel  10 , the microcapsules  21 ,  22 , and  23  of color being respectively magenta (M), yellow (Y), and cyan (C) are placed so as to sequentially align each two column in the column direction repeatedly as shown in  FIGS. 2A and 2B . It is deemed that a display unit  20  of one pixel comprises six microcapsules  21 ,  22 , and  23  continuing each two microcapsules of the three different types and the display panel is controlled. Thus, the display becomes possible in full color per each pixel. 
         [0067]    The second electrode  13  is electrode which faces the first electrode  12  by a layer of the microcapsules and is formed over the upper substrate  14 . In the present embodiment, the second electrode  13  is a transparent electrode formed so as to cover the whole of the microcapsules arranged two dimensionally with the same potential as shown in  FIG. 2B . 
         [0068]    The upper substrate  14  is a substrate at the display surface side of the display panel  10 . The upper substrate  14  and the second electrode  13  are formed by a transparent member. Thus, a state of the microcapsules, i.e. a state of color display of a desired picture by the microcapsules, can be observed when the display panel  10  is seen from the upper substrate  14  side which is the display surface. 
         [0069]    Next, a production method of the display panel  10  with the such structure is explained. 
         [0070]    First, three types of dispersion media are formed by using the dispersion media of three colors-magenta, yellow, and cyan, and the white pigment particles. 
         [0071]    Next, three types of microcapsules respectively including the three types of dispersion media are formed. 
         [0072]    The diameters of the formed microcapsules are uniformized by any of screening or specific gravity separation method etc. 
         [0073]    Then, three types of the microcapsules of the uniformized diameters are sequentially placed on each divisional electrode of the first electrode  12  formed over the lower substrate  11  in an arrangement shown in  FIG. 2B  without a gap. 
         [0074]    The arrangement method of the microcapsules according to the present invention will be explained referring to  FIGS. 5A to 5D . 
         [0075]    First, as shown in  FIG. 5A , the microcapsules  23  each including cyan (C) dispersion media is uniformly coated onto the lower substrate  11 , on which the divisional electrode  12  is formed, by using the optical hardening resin as the binder material  15 . 
         [0076]    Next, as shown in  FIG. 5B , the binder material  15  is hardened by selectively irradiating light beam to the only portions desired to place the microcapsules  23  each including cyan (C) dispersion media, i.e. the only electrodes  12   c  of positions where cyan color is a lit, by using the photomask  30 . The binder material  15  of the portion not hardened is removed by washing in water. 
         [0077]    As a result, the microcapsules  23  each including cyan (C) dispersion media can be selectively and accurately placed only on the display electrode  12   c  corresponding to cyan, as shown in  FIG. 5C . 
         [0078]    Thereafter, a similar procedure mentioned above is repeated, whereby the microcapsules  22  including yellow (Y) dispersion media, and the microcapsules  21  including magenta (M) dispersion media are sequentially placed at predetermined positions. 
         [0079]    Namely, first, the microcapsules  22  including yellow (Y) dispersion media are coated on the portions where the microcapsules  23  including cyan (C) dispersion media have not already been placed, over the lower substrate  11 , on which the divisional electrode  12  is formed, by using the optical hardening resin as the binder material  15 . 
         [0080]    Next, the binder material  15  is hardened to selectively irradiating the light beam at the only locations desired to place the microcapsules  22  including yellow (Y) dispersion media by using the photomask  30 . The binder material  15  of the portions not hardened is removed by washing in water. 
         [0081]    Finally, the microcapsules  21  including magenta (M) dispersion media are coated on the portions, where the microcapsules  23  including cyan (C) dispersion media and the microcapsules  22  including yellow (Y) dispersion media are not placed, over the lower substrate  11  on which the divisional electrode  12  is formed, by using the optical hardening resin as the binder material  15 . 
         [0082]    The binder material  15  is hardened to selectively irradiating the light beam at the only locations desired to coat the microcapsules  21  including magenta (M) dispersion media through the use of the photomask  30 . 
         [0083]    At a result of this process, the microcapsules  21 ,  22 , and  23  respectively including magenta (M), yellow (Y), and cyan (C) are respectively placed on divisional electrodes  12   m,    12   y,  and  12   c,  corresponding to each color selectively and accurately, as shown in  FIG. 5D . 
         [0084]    Once the microcapsules  21 ,  22 , and  23  are placed over the lower substrate  11 , on which the first electrodes  12  are formed, the upper substrate  14  on which the second electrodes  13  are formed and the lower substrate  11  are bonded together, so as to sandwich the microcapsules  21 ,  22 , and  23  therebetween. 
         [0085]    In this way, the display panel  10  with a structure as shown in  FIGS. 2A and 2B , can be produced. 
         [0086]    As explained above, in the production method of the display panel of the present embodiment, an electrophoretic display panel capable of full color display is produced by performing a step in which the microcapsules including dispersion media of desired color are previously coated onto the whole of the substrate  11  and the microcapsules of desired color are placed at the desired position by irradiating the light beam at the portions desired to place that color&#39;s microcapsules for each color of magenta (M), yellow (Y), and cyan (C). Therefore, a high accuracy full color electrophoretic display panel can be produced, in which the microcapsules of each color is accurately placed, by a comparatively simple process without requiring a process of special accurate position control. 
         [0087]    Note that the production method of the display panel in the present invention is not limited to the first and second embodiments as aforementioned, and various preferred modifications are available. 
         [0088]    For instance, in the second embodiment, the production method of the display panel  10 , which is capable of full color display, is described a specific panel, however, it is clear that the production method of the display panel in the present invention can be applied to a monochrome display panel. 
         [0089]    Although the display panel of an electrophoretic system is described in the first and second embodiments as an example, a display panel of a magnetophoretic system can also be configured by a system similar to this. In that case, charged pigment particles may be changed to magnetic powder, and a voltage application means may be changed to a magnetic field application means. 
         [0090]    Then, any means which is normally known may be used as the magnetic field application means to be comprised in the display panel. For instance, various types of magnetic heads or magnets various types may be used. 
         [0091]    Also, three types of colors-red, green, and blue which are additional color mixture three primary colors may be used instead of the three types of colors-magenta, yellow, and cyan which are the subtractive color mixture three primary colors are used for the color of the dispersion media in the second embodiment. Also, combinations of other colors may be used. 
         [0092]    Although the color of the charged pigment particles is white, it is preferable that the color of the charged pigment particles are black, for instance, when the additional color mixture three primary colors are used for the color of the dispersion media, and such black color may be adopted. The color of the charge pigment particles may be arbitrary determined. 
         [0093]    Further, although the three types of microcapsules corresponding to the three primary colors are formed by changing the color of the dispersion media in the second embodiment, color of the dispersion media is identical and the three types of microcapsules corresponding to the three primary colors may be formed by changing the color of the microcapsules. 
         [0094]    A case of a stripe arrangement in which each two columns of the same color is continuously connected in the column direction is described as an example as shown in  FIG. 2B , as for the two dimensional arrangement of the three types of the microcapsules of the three primary colors in the second embodiment. However, the arrangement of the three types of microcapsules is not limited to this embodiment. For instance, the microcapsules may be vertically and horizontally arranged orderly, a mosaic configuration may be applied such that directions are sequentially changed vertically and horizontally. Also, a triangle arrangement may be applied such that the microcapsules, per se, may be arranged in a zigzag manner to form a triangle arrangement. 
         [0095]    Furthermore, the structure of one pixel may also be defined by six microcapsules being in series in one two, as in the present embodiment, or for instance, the structure of one pixel may also be defined by three microcapsules being in series in one row or an arrangement of 2.times.2 of a number of four microcapsules such as having a number of two microcapsules of any colors and may be arbitrarily determined. 
         [0096]    And, the areas to place the microcapsules is limited by the photomask having the shape corresponding to the electrode or magnetic poles in the production method of the display panel according to the present invention. Therefore, aligning and placing the microcapsules orderly in the first and the second embodiments as aforementioned are not necessary if the microcapsules is small enough for the electrode. It may be better to position the microcapsules to be a layer as uniform as possible and to select the microcapsules to fix by using the photomask corresponding to the shape of the electrode or the pixel. Such the method is also falls in the scope of rights of the present invention. 
         [0097]    As explained above, the production method of the display panel, using electrophoretic or magnetophoretic, which can selectively and accurately place the microcapsules at the desired positions, can be provided according to the present invention. Thus, the production method of the display panel, using electrophoretic or magnetophoretic capable of precision display or full color display, can be provided. Further, the display panel, using electrophoretic or magnetophoretic selectively and accurately placing the microcapsules at the desired position, can be provided. 
       INDUSTRIAL APPLICABILITY 
       [0098]    The production method of the display panel in the present invention can be applied to a display panel using the microcapsules housing the electrophoretic or magnetophoretic particles. 
       Description of References 
       [0000]    
       
           10  . . . display panel 
           11  . . . lower surface substrate 
           12  . . . first electrodes (divisional electrodes) 
           13  . . . second electrode 
           14  . . . upper surface substrate 
           15  . . . binder material 
           20  . . . pixel display unit 
           21  . . . microcapule of cyan (C) 
           22  . . . microcapule of magenta (M) 
           23  . . . mirocapsule of yellow (Y) 
           24 ,  25 ,  26  . . . dispersion media 
           27  . . . white pigment particles 
           30  . . . photomask 
           41  . . . substrate 
           42  . . . electrodes 
           43  . . . microcapsule 
           44  . . . binder material 
           45  . . . photomask