Abstract:
A manufacturing method of a color filter is capable of achieving improvement in efficiency of use of materials and simplification in process, and forming highly accurate colored patterns. 
     The manufacturing method includes the steps of: continuously discharging a coloring matter from a nozzle to apply the coloring mater to between the banks  12  on the glass substrate while, with a nozzle being scanned with respect to a glass substrate  10  on which surface a predetermined pattern of light-blocking bank  12  is formed, intermittently feeding the glass substrate at a predetermined pitch in a direction orthogonal to the scanning direction; aligning and superimposing on the backside of the glass substrate a mask plate in which a light transmission part corresponding to an active region of a color filter is formed, and exposing the glass substrate to light from backside through the mask plate to cause a coloring matter having been applied at a part corresponding to an active region of the color filter to be cured; and developing the surface side of the glass substrate to dissolve and remove the uncured coloring matter having been applied at a part corresponding to the non-active region of a color filter.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method for manufacturing a color filer for use in, e.g., color liquid crystal displays, organic EL (electro luminescence) display units, or FED (filed emission displays). 
     2. Description of the Related Art 
     A color filter of, for example, color liquid crystal displays has been conventionally manufactured by such methods as staining in which a staining base material having photosensitivity is applied onto a transparent substrate, the staining base material is exposed to light through a photo-mask to develop, and the staining base material having been formed in a predetermined pattern is stained to be a colored layer; pigment dispersion in which a photosensitive resist in which coloring pigments have preliminarily been dispersed is applied onto a transparent substrate, and the photosensitive resist is exposed to light through a photo-mask and developed to form a predetermined pattern of colored layer; or printing in which using the printing technique, printing inks are directly applied onto a transparent substrate in a predetermined pattern by, e.g., ink-jet printing to obtain a colored layer as disclosed in, for example, the Japanese Patent Publication (unexamined) No. 235901/1988. 
     SUMMARY OF THE INVENTION 
     In the method of manufacturing a color filter by the method of staining or pigment dispersion, material loss is inevitable in the process of applying a staining base material having photosensitivity or a photo-sensitive resist onto a transparent substrate by, e.g., spin coating; and moreover it is necessary to repeat the development process or the cleaning process every time colored patterns of each color of red, green and blue are formed. Like this, efficiency of use of materials is low and the process is complicated, which is one of main causes of high cost of liquid crystal displays. Whereas, in the printing method, a problem exists in that highly accurate colored patterns are hard to form. 
     The present invention was made in view of the state of arts as described above, and has an object of providing a manufacturing method of a color filter by which it is possible to achieve improvement in efficiency of use of materials and simplification of process, eventually making it possible to form highly accurate colored patterns. 
     A manufacturing method of a color filter according to claim  1 , in which coloring matters are applied onto a transparent substrate on the surface of which a predetermined pattern of light-blocking bank functioning as a black matrix is preliminarily formed, comprises the steps of: continuously discharging a coloring matter having photosensitivity from a nozzle to apply the coloring mater to between light-blocking banks on the transparent substrate while, with a nozzle being scanned with respect to the mentioned transparent substrate, causing the transparent substrate and the nozzle to move intermittently at a predetermined pitch relatively in a direction orthogonal to a direction scanning thereof; aligning and superimposing a mask, in which a light transmission part corresponding to an active region of a color filter is preliminarily formed, on the backside of the mentioned transparent substrate, and exposing the transparent substrate to light from the backside through this mask to cause the coloring matter having been applied to a part corresponding to an active region of the color filter to be cured; and developing a surface side of the mentioned transparent substrate to dissolve and remove an uncured coloring matter having been applied at a part corresponding to the non-active region of the color filter, and the uncured coloring matter having been applied onto the mentioned light-blocking bank. 
     The invention according to claim  2  is the manufacturing method according to claim  1 , and in which at least a surface of the mentioned light-blocking bank has liquid-repellent properties with respect to the coloring matter. 
     In the manufacturing method of a color filter of the invention according to claim  1 , coloring matters are just discharged continuously from a nozzle onto a transparent substrate on which light-blocking banks are formed, so that material loss is suppressed to be low. Further, to form a pattern of coloring matters, no process of exposure, development, or cleaning is needed. Furthermore, the coloring matters are applied to between the light-blocking banks, so that it is possible to make the highly accurate application of coloring matters. In addition, out of the coloring matters having been continuously discharged from the nozzle to be applied onto the transparent substrate, unnecessary coloring matters having been applied at a part corresponding to the non-active region of the color filter, and unnecessary coloring matters having been applied onto the light-blocking banks are removed from the transparent substrate by exposure from backside of the transparent substrate and by development on the front side. Thus, there is no application of coloring matters at the non-active part on the transparent substrate. 
     As a result, in case of employing the manufacturing method of a color filter of the invention according to claim  1 , it is possible to achieve improvement in efficiency of use of materials and simplification of process, and to form highly accurate colored patterns. 
     In the manufacturing method of a color filter according to claim  2  of the invention, it is possible to reliably prevent mixing of colors caused by that coloring matters overflow the light-blocking banks in the application process of coloring matters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows one of preferred embodiments according to the present invention for explaining the process in the manufacturing method of a color filter, and is a schematic perspective view showing the state in which banks are formed on a glass substrate. 
         FIG. 2  is a partially perspective view of a part of the glass substrate shown in  FIG. 1  being enlarged. 
         FIG. 3  is a view for explaining the process in the manufacturing method of a color filter, and is a schematic perspective view showing the state of applying a coloring matter onto the surface of the glass substrate. 
         FIG. 4  is likewise a partially enlarged perspective view showing the state of applying a coloring matter onto the glass substrate. 
         FIG. 5  is likewise a partially enlarged plan view showing the state in which coloring matters are applied onto the surface of the glass substrate. 
         FIG. 6  is likewise a longitudinal cross section showing the state in which the coloring matters are applied and adhered onto the non-active region of the glass substrate. 
         FIG. 7  is likewise a view showing the state in which a mask plate is aligned on the backside of the glass substrate to be superimposed, and is a schematic perspective view taken from the backside of the glass substrate. 
         FIG. 8  is likewise a longitudinal cross section showing the state in which the glass substrate is exposed to light through a mask plate from the backside. 
         FIG. 9  is likewise a longitudinal cross section showing the state in which the surface side of the glass substrate is developed, and the uncured coloring matters having been applied in the non-active region of the glass substrate are dissolved and removed. 
         FIG. 10  is likewise a partially enlarged longitudinal cross section showing the state in which coloring matters remain in the active region of the glass substrate after the development process. 
         FIG. 11  shows another embodiment according to the invention, and is a partially enlarged plan view showing the state in which coloring matters are applied on the surface of a glass substrate. 
         FIG. 12  is a schematic plan view showing one example of the construction of a coloring matter applicator for use in carrying out the manufacturing method of a color filter according to the invention. 
         FIG. 13  is a schematic front view of the coloring matter applicator shown in  FIG. 12 , and shows a pipeline together. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Several preferred embodiments of the present invention are hereinafter described referring to the drawings. 
       FIGS. 1 through 10  shows one preferred embodiment of the invention, and are views for explaining each step of the manufacturing method of a color filter. 
     Prior to manufacturing a color filter, first light-blocking banks of a predetermined pattern are formed on a transparent substrate, for example, a transparent glass substrate.  FIG. 1  is a schematic perspective view showing the state in which banks are formed on the glass substrate, and  FIG. 2  is a partial perspective view of a part thereof being enlarged.  FIG. 1  shows an example of having six screens in which six active regions A are provided corresponding to the active parts of a color filter. 
     A bank  12  is a member functioning as a black matrix in the color filter, and is made of light-blocking material. For example, this bank  12  is formed by applying a photosensitive resin material onto the surface of a glass substrate  10 , and exposing the photosensitive polymeric film to light through a photo-mask to be developed to manufacture in a predetermined pattern, being in a striped pattern in this example. It is desirable that at least the surface of the bank  12  is liquid-repellent with respect to pigment dispersion-type material (coloring matter) as described later. A method for obtaining liquid-repellent properties includes the step of: forming a bank  12  itself with the use of a photo-sensitive resin material having liquid-repellent properties, or forming a bank  12  with the use of a photo-sensitive resin material (having no liquid-repellent properties); and thereafter applying an ink-repellent matter onto the surface thereof to deposit and form a liquid-repellent film. As material of forming a liquid-repellent film, it is desirable to employ a resin material including at least one of silicon and fluorine. It is preferable to use, for example, a silicon resin or a fluorine resin. By making a bank  12  liquid-repellent as described above, it is possible to reliably prevent the mixing of colors caused by the fact that coloring matters overflow the banks  12 . 
     Next, using the below-described manufacturing apparatus, a color filter is formed on a glass substrate  10  on which the light-blocking banks  12  have preliminarily been made. First, pigment dispersion-type materials (coloring matters) of each color that are obtained by causing each of coloring pigments of read, green and blue to disperse in respective resin base materials (negative-type resists) having photosensitivity are applied to the surface of the glass substrate  10  respectively. That is, as shown in a schematic perspective view of  FIG. 3 , while with a nozzle  14  scanned in a direction indicated by the arrow “a” with respect to the glass substrate  10 , the glass substrate  10  and the nozzle  14  are intermittently moved relatively at a predetermined pitch in a direction indicated by the arrow “b” orthogonal to the scanning direction thereof, a coloring matter  16  is continuously discharged from the nozzle  14  to be applied in an elongated groove  18  formed between the adjacent banks  12  on the glass substrate  10 , as shown in a partially enlarged perspective view of  FIG. 4 . In the example shown, the position in a direction indicated by the arrow “b” orthogonal to the foregoing scanning direction of the nozzle  14  is fixed, and the glass substrate  10  is intermittently fed in the direction indicated by arrow “b”. A pitch of the intermittent feed of the glass substrate  10  in the direction indicated by arrow “b” is to be [width dimension of a bank  12 +width dimension of the elongated groove  18 ]×3, for example, when one color of coloring matter is discharged from one nozzle  14  in one scanning step, or three nozzles  14  that discharge three colors of coloring matters into respective elongated grooves  18  adjacent to each other are simultaneously scanned. In this respect, one scanning means that a nozzle  14  moves from one end to the other end of a glass substrate  10 . The nozzle  14  makes one reciprocating motion upon two times of scanning operation. Further, the glass substrate  10  is fed intermittently by one pitch at each time of one scanning of the nozzle  14 . The scanning of the nozzle  14  is made at high speed, for example, approximately 3 m/sec., while discharge rate of a coloring matter  16  from the nozzle  14  is a very small, for example, 80 μl/min to 250 μl/min. 
     In the process of applying coloring matters as described above, striped pattern of application parts of coloring matters  16 R,  16 G, and  16 B of respective colors of red, green and blue, and banks  12  having light-blocking effect are formed in an active region A of the glass substrate  10 , as shown in a partially enlarged plan view of  FIG. 5 . On the other hand, the nozzle  14  is scanned at high speed, and coloring matters are continuously discharged from the nozzles  14 , so that, as shown in  FIG. 6 , each color of coloring matters  16  is applied and adhered also into a non-active region B of the glass substrate  10  as well.  FIG. 6  is a longitudinal section of the glass substrate  10  taken in a direction indicated by arrow V in  FIG. 1 . After this application process, the coloring matters  16 R,  16 G, and  16 B having been applied onto the glass substrate  10  are subjected to baking. 
     Subsequently, as shown in  FIG. 7  being a schematic perspective view of a glass substrate  10  taken from the backside, a mask plate  20  is aligned and superimposed on the backside of the glass substrate  10 , and a light U such as ultraviolet radiation is applied from the backside of the glass substrate  10  via the mask plate  20  as shown in a longitudinal section of  FIG. 8 . Light transmission openings  22  are formed in the mask plate  20 , corresponding to the active parts (active regions A of the glass substrate  10 ) of a color filter. A part other than the light transmission openings  22 , that is, a part corresponding to the non-active part (non-active region B of the glass substrate  10 ) is a light-blocking surface  24 . This mask plate  20  is aligned using alignment marks (not shown) and superimposed on the backside of the glass substrate  10 , and thereafter exposed to light. As a result, the coloring matters  16  having been applied onto the active region A of the glass substrate  10  are photo-cured. Whereas, the coloring matters  16  having been applied onto the non-active region B of the glass substrate  10  are shielded from light with the light-blocking surface  24  of the mask plate  20 , so that they are not exposed to light, and remain uncured. 
     Subsequently to the exposure process, the surface side of the glass substrate  10  is developed. By this development, the coloring matters  16  having been applied to the non-active region B of the glass substrate  10  as shown in  FIG. 6  are dissolved and removed as shown in  FIG. 9 , and a glass surface in the non-active region B will be exposed. In addition, even if the coloring matters adhere partially to the surface of banks  12  in the active region A of the glass substrate  10  in the application process of coloring matters, those coloring matters on the banks  12  are shielded from light with the banks  12  having light-blocking effect in the exposure process, so that they are not exposed to light, and remain uncured. Therefore, in the development process, the coloring matters on the banks  12  are dissolved and removed. On the other hand, as shown in  FIG. 10  being a partially enlarged longitudinal sectional view taken in a direction indicated by the arrow W orthogonal to the direction indicated by arrow V is shown in  FIG. 1 , the coloring matters  16 R,  16 G and  16 B of each color of red, green and blue remain as they are between respective banks  12 . Then, the active regions A of the glass substrate  10  are cut off, whereby the production of six pieces of striped color filters is completed. 
     In addition, although the banks  12  are formed in a striped pattern according to the above-mentioned embodiment, it is preferable that, as shown in a partially enlarged plan view of  FIG. 10  in a similar manner to  FIG. 5 , the banks  26  are formed in a grid pattern, and the coloring matters  16 R,  16 G and  16 B of each color of red, green and blue are applied into each of micro-concave parts  28  surrounded by the grid-shaped banks  26 . In this modification, since the coloring matters are continuously discharged from the nozzles  14  to be applied linearly onto the glass substrate  10  in the application process of coloring matters, the coloring matters are also applied and adhered to the surface of the banks  26  in the active region A of the glass substrate  10 . Even in such a modification, the coloring matters having been applied onto the surface of the bank  26  are shield from light with the banks  26  having light-blocking property, so that they are not exposed to light and remain uncured. Accordingly, in the development process, the coloring matters having been applied onto the surface of the banks  26  are dissolved and removed along with the uncured coloring matters having been applied to the non-active region B of the glass substrate  10 , so that there is no problem at all. 
     Now, one example of the specific construction of a coloring matter applicator for use in the above-mentioned application process of coloring matters is described with reference to  FIGS. 12 and 13 .  FIG. 12  is a schematic plan view of a coloring matter applicator, and  FIG. 13  is a schematic front view of this apparatus showing a pipeline together. 
     This apparatus comprises a stage  30  holding a glass substrate  10  on which surface banks  12  are formed; a nozzle unit  32  holding three nozzles  14 R,  14 G and  14 B that continuously discharge coloring matters of each color of red, green and blue; a nozzle scanning mechanism  34  causing this nozzle unit  32  to scan with respect to the glass substrate held on the stage  30 ; an intermittent feed mechanism causing the stage  30  to move intermittently at a predetermined pitch in a direction orthogonal to the scanning direction of the nozzle unit  32  with respect to the nozzle scanning mechanism  34 ; an alignment mechanism (not shown) making the glass substrate  10  aligned with respect to the stage  30 ; and the like. The nozzles  14 R,  14 G and  14 B of the nozzle unit  32  are connected to respective coloring matter supply systems  38  (only the coloring matter supply system  38  of red is shown in  FIG. 13 , and showing the supply systems of coloring matters of each color of green and blue are omitted herein). The coloring matter supply systems  38  are formed of coloring matter reservoirs  40 R,  40 G,  40 B that store coloring matters; coloring matter supply pipes  42  that provide a channel connection between the coloring matter reservoirs  40 R,  40 G and  40 B and the nozzles  14 A,  14 G and  14 B; and constant pressure pumps  44 , mass-flow meters  46 , manometers  48  and filters  50  that are interposed on the way of the coloring matter supply pipes  42 . 
     The nozzle scanning mechanism  34  causes the nozzle unit  32  to move in a reciprocating manner laterally at high speed, for example, 3 m/sec. The intermittent feed mechanism  36  intermittently feeds the stage  30  that holds the glass substrate  10  at a predetermined pitch every time the nozzle unit  32  makes one scanning from one end side to the other end side. The apparatus shown in the drawing is arranged such that first red color of coloring matter is applied in a striped pattern to the entire glass substrate  10 , subsequently green color of coloring matter is applied in a striped pattern to the entire glass substrate  10  adjacent to the application part of the coloring matter of red color, and finally blue color of coloring matter is applied in a striped pattern to the entire glass substrate  10  adjacent to the application part of the coloring matter of green color. The intermittent mechanism  36  causes the stage  30  holding the glass substrate  10  to intermittently move by three lines of banks  12  and elongated grooves  18  every time the nozzle unit  32  makes one scanning from one end side to the other side. 
     In addition, it is preferable that three nozzles  14 R,  14 G and  14 B are held at the nozzle unit  32  positioned at intervals of [width dimension of a bank  12 +width dimension of the elongate groove  18 ] in a direction orthogonal to the scanning direction of the nozzle unit  32 ; and the stage  30  is made to move intermittently by three lines of banks  12  and elongated grooves  18  while coloring matters of each color of red, green and blue are continuously discharged in a synchronous manner from three nozzles  14 R,  14 G and  14 B to make the synchronous application of respective colors of coloring matters of red, green and blue onto the glass substrate  10 . In this manner, the location, the number, and the discharge manner of nozzles, or the pitch of intermittent feed of the stage  30  are not limited to the above-described example. It is also preferable that instead of causing the stage  30  to move intermittently at a predetermined pitch, the stage  30  is fixed, and nozzle unit  32  is made to move intermittently at a predetermined pitch in a direction orthogonal to the foregoing scanning direction. 
     Moreover, according to the above-mentioned embodiment, coloring matters are applied onto a glass substrate  10  provided with six active regions A. The invention is not limited to this embodiment. The method of the invention is applicable to a glass substrate provided with a plurality of active regions. Further, not being limited to glass substrate provided with a plurality of active regions, the method of the invention can be likewise applied to a glass substrate including one active region, and in which a non-active region is located therearound to obtain the same function and advantage as in the above-mentioned embodiment.