Patent Publication Number: US-7218464-B2

Title: Aligning-assembling method for color wheel

Description:
This application is a Divisional of application Ser. No. 10/386,463, filed on Mar. 13, 2003, now U.S. Pat. No. 7,083,882 and for which priority is claimed under 35 U.S.C. § 120; and this application claims priority of Application Nos. 091119062 filed in Taiwan, R.O.C. on Aug. 22, 2002, 091123309 filed in Taiwan, R.O.C. on Oct. 9, 2002, and 091124813 filed in Taiwan, R.O.C. on Oct. 24, 2004, under 35 U.S.C. § 119; the entire contents of all are hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a coating method for a color filter and an aligning-assembling method for a color wheel and, in particular, to the coating method for the color filter and the aligning-assembling method for the color wheel, both of which are used in projection technology. 
   2. Description of the Related Art 
   In recent years, demand has arisen for a color filter used in a device such as a liquid crystal display or a color wheel. The color filter separates the light into three fundamental colors (i.e. red, green and blue), and then the color filter further mixes these three fundamental colors to create the different colors in different ratios. 
   In general, coating three fundamental colors on a substrate makes the color filter. The shape, the size and the arrangement of the color filter are adjusted according to practical needs. For example, the color filter is composed of three sectors of red, green and blue. Also, the color filter is a ring-shaped filter composed of one transparent block and three or more filter sectors of red, green and blue. 
   In the conventional color filter coating technology, a pattern on a mask is transferred to a glass substrate by exposure and development. Herein, the position of the mask and the substrate is aligned by mechanical alignment. Because the accuracy of the mechanical alignment is insufficient, the error in the coating position may increase. Further, the reliability of the color filter may also decrease. 
   In addition, the color wheel  6  mainly includes a motor  61  and a color filter  62 . As shown in  FIG. 1 , the color filter  62  is mounted on the axis of the motor  61 . The color filter  62  rotates together with the motor  61  and generates the light rays of several colors. 
   In the conventional aligning-assembling method for the color wheel, the color filter and the motor are set on the fixing jig, and then both of them are aligned by a mechanical method. After alignment, the color filter and the motor are assembled to create the color wheel. Generally, the motor rotates at a speed higher than 7200 rpm. When the rotation center of the motor is away from the central axis of the rotation shaft (i.e., when the rotation center is not located on the central axis of the rotation shaft), the operation of the color wheel may be adversely influenced by vibration and noise. Further, the operational reliability of the color wheel may decrease. For above-mentioned reasons, the accuracy of aligning the color wheel is very critical. However, the accuracy of the mechanical alignment is insufficient, and the speed of the mechanical alignment is also very slow. Therefore, the mechanical alignment is inapplicable in industrial applications. 
   It is therefore an important objective of the invention to provide a coating method for the color filter and an aligning-assembling method for the color wheel to solve the above-mentioned problem. 
   SUMMARY OF THE INVENTION 
   An objective of the invention is to provide a coating method for a color filter, which may have the advantages of increasing the accuracy, increasing operational reliability, and reducing the fabrication time. 
   Another objective of the invention is to provide an aligning-assembling method for a color wheel, which has the advantages of increasing the accuracy, and reducing the fabrication time. 
   To achieve the above-mentioned objectives, the invention provides a coating method for a color filter, including the steps of: coating a first photoresist layer on a substrate; forming at least an aligning pattern and a first color film pattern on the first photoresist layer by exposure and development; coating a first dye on the aligning pattern and the first color film pattern; stripping the first photoresist layer; coating a second photoresist layer on the substrate, wherein the aligning pattern and the first color film pattern are formed on the substrate; aligning position by using the aligning pattern of the substrate; forming a second color film pattern on the second photoresist layer by exposure and development; coating a second dye on the second color film pattern; and stripping the second photoresist layer. 
   To achieve the above-mentioned objectives, the invention provides an aligning-assembling method for a color wheel. The method includes the following steps. First, at least a first aligning pattern is formed on a housing of a motor. Then, at least a second aligning pattern of the color filter formed above the housing is provided. Afterward, the first aligning pattern and the second aligning pattern are aligned by an optical alignment. Finally, the color filter and the housing are assembled. 
   As mentioned above, the invention provides a coating method for the color filter and an aligning-assembling method for the color wheel, in both of which the optical alignment is used. Compared to the prior art, the accuracy of the alignment may be increased and the operational reliability of the color filter and the color wheel may also be increased. Further, the fabrication time of the color filter and the color wheel may be reduced. Moreover, the fabrication cost may also be reduced. In addition, the vibration and noise caused by the color wheel may be reduced. 
   Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
       FIG. 1  is a schematic illustration that shows a pictorial view of a conventional color wheel; 
       FIG. 2  is a block diagram of the coating method for the color filter according to the first embodiment; 
       FIGS. 3A to 3I  are partially enlarged views that schematically illustrate the first embodiment; 
       FIG. 4  is a partially enlarged view that schematically illustrates the second embodiment; 
       FIG. 5  is a block diagram of the aligning-assembling method for the color wheel according to the third embodiment; 
       FIG. 6A to 6C  are schematic elevations that schematically illustrate the housing of the third embodiment; 
       FIG. 7A to 7C  are schematic elevations that schematically illustrate the color filter of the third embodiment; 
       FIGS. 8A and 8B  schematically illustrate the third embodiment; and 
       FIG. 9  is a pictorial view of the color wheel according to the third embodiment. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. 
   As shown in  FIG. 2 , a first embodiment of the disclosed coating method for a color filter includes the following steps. First, a substrate is coated with a first photoresist layer (S 01 ). The first photoresist layer is formed with at least an aligning pattern and a first color film pattern by exposure and development (S 02 ). The aligning pattern and the first color film pattern are coated with a first dye (S 03 ). Then, the first photoresist layer is stripped (S 04 ). Afterwards, the substrate is coated with a second photoresist layer, herein, the aligning pattern and the first color film pattern are formed on the substrate (S 05 ). The aligning pattern of the substrate is used to align the position (S 06 ). The second photoresist layer is formed with a second color film pattern by exposure and development (S 07 ). The second color film pattern is coated a second dye (S 08 ). Finally, the second photoresist layer is stripped (S 09 ). 
   Referring to  FIG. 3A , the substrate  101  is coated with a first photoresist layer  102  in step S 01 . The first photoresist layer  102  is made of a mixture of a resin, a sensitizer and the solvent. Herein, the first photoresist layer  102  is a negative photoresist layer. Namely, when a specific wavelength light exposes the first photoresist layer  102 , the first photoresist layer  102  becomes a cross-linking structure, and is insolvable in a developing solution. 
   Referring to  FIG. 3B , a mask  2  is set above the substrate  101 . Herein, an aligning pattern  21  (as shown in  FIG. 3B ) and a first color film pattern  22  (as shown in  FIG. 3B ) are formed on the mask  2 . Then, the aligning pattern  21  and the first color film pattern  22  on the mask  2  are transferred to the first photoresist layer  102  by being exposed to a specific wavelength of light. 
   Next, referring to  FIG. 3C , the first photoresist layer  102  is formed with at least an aligning pattern  103  (as shown in  FIG. 3C ) and a first color film pattern  104  (as shown in  FIG. 3C ) by exposure and development in step S 02 . 
   In the current embodiment, the aligning pattern  103  may be any shape and any size. The number and the type of the aligning pattern  103  are one or more. 
   Referring again to  FIG. 3C , the exposed part of the first photoresist layer  102  is then removed by using a developing solution. 
   In step S 03 , the aligning pattern  103  and the first color film pattern  104  are coated with the first dye (ex: red). The first color film pattern  106  coated with the first dye and the aligning pattern  105  coated with the first dye are formed on the substrate  101 . 
   The first photoresist layer  102  is stripped in step S 04 . In the current embodiment, the first photoresist layer  102  is removed from the substrate  101  by a wet-stripped method or a dry-stripped method. The first color film pattern  106  coated with the first dye and the aligning pattern  105  coated with the first dye are formed on the substrate  101 , as shown in  FIG. 3D . 
   As shown in  FIG. 3E , the substrate  101  is coated with a second photoresist layer  107  in step S 05 . Herein, the aligning pattern  105  coated with the first dye and the first color film pattern  106  coated with the first dye are formed on the substrate  101 . In the current embodiment, the second photoresist layer  107  has the same feature and function as the first photoresist layer  102 . 
   As shown in  FIG. 3F , the aligning pattern  105  coated with the first dye is used to align the position in step S 06 . In other words, the aligning pattern  105  coated with the first dye on the substrate  101  is aligned with an aligning pattern  31  on a mask  3  by an optical process. Herein, a second color film pattern  32  is also formed on the mask  3 . 
   Next, as shown in  FIG. 3G , the second photoresist layer  107  is formed with a second color film pattern  108  by exposure and development in step S 07 . 
   In step S 08 , the second color film pattern  108  is coated a second dye (ex: green). 
   As shown in  FIG. 3H , the second photoresist layer  107  stripped in step S 09  is using the same way in step S 04 , so that the first color film pattern  106  coated with the first dye, the second color film pattern  109  coated with the second dye and the aligning pattern  105  coated with the first dye are formed on the substrate  101 . 
   Finally, repeating step S 05  to step S 08 , the third color film pattern  110  coated with the third dye (ex: blue) is formed on the substrate  101 , as shown in  FIG. 31 . 
   In the current embodiment, the color filter, which is composed of the first color film pattern  106  coated with the first dye, the second color film pattern  109  coated with the second dye, and the third color film pattern  110  coated with the third dye are all formed by the above-mentioned method. 
   Of course, the different shape and the different style of the color filter  1  may also be made in the same way, as shown in  FIG. 4 . 
   Referring again to  FIG. 4 , a second embodiment of the invention provides a substrate  401  on which the first color film pattern  404  coated with the first dye, the second color film pattern  405  coated with the second dye, the third color film pattern  406  coated with the third dye, and the aligning pattern  402 ,  403  are formed. 
   In the current embodiment, as shown in  FIG. 4 , the aligning pattern  402  is used to avoid the displacement of the horizontal direction and the vertical direction in the alignment. Herein, the aligning pattern  402  is located on one side of those color film pattern  404 ,  405  and  406 . 
   In addition, the aligning pattern  403  is used to avoid the displacement of rotation (counterclockwise or clockwise) in the alignment. Referring again to  FIG. 4 , the aligning pattern  403  is located at the relative center of those color film pattern  404 ,  405  and  406 . 
   In the current embodiment, the number and the size of the aligning patterns  402 ,  403  are adjusted according to practical needs. 
   Additionally, as shown in  FIG. 5 , a third embodiment of the invention provides an aligning-assembling method for a color wheel  5 , which includes a color filter  52 . The method includes following steps. First, at least a first aligning pattern is formed on a housing of a motor (S 11 ). Then, at least a second aligning pattern of the color filter formed above the housing is provided (S 12 ). Afterwards, the first aligning pattern and the second aligning pattern are aligned by optical alignment (S 13 ). Finally, the color filter and the housing are assembled (S 14 ). 
   As shown in  FIG. 6A , at least one first aligning pattern  511  is formed on the housing  51  in step S 11 . Herein, the first aligning pattern  511  may include a cross pattern which is used to avoid the displacement of the horizontal direction and the vertical direction in the alignment. Additionally, the first aligning pattern  511  may also include two sector patterns located opposite each other, as shown in  FIG. 6B . These sector patterns are used to avoid the displacement of the rotation in the alignment. Of course, the housing  51  further includes at least a third aligning pattern  512 , so that the aligning pattern on the housing  51  may both include the cross pattern and the sector pattern, as shown in  FIG. 6C . 
   In step S 12 , at least a second aligning pattern  521  of the color filter  52  formed above the housing  51  is provided. Herein, the second aligning pattern  521  may include a cross pattern, as shown in  FIG. 7A . Additionally, the second aligning pattern  521  may also include two sector patterns located opposite each other, as shown in  FIG. 7B . Of course, the color filter  52  further includes at least a fourth aligning pattern  522 , so that the aligning pattern of the color filter  52  both includes the cross pattern and the sector pattern, as shown in  FIG. 7C . 
   In the current embodiment, the cross pattern and the sector pattern of the second aligning pattern  521  and the fourth pattern  522  have the same features and functions as the first aligning pattern  511  and the third aligning pattern  512 , detailed description thereof will be omitted. 
   Herein, the second aligning pattern  521  and the fourth aligning pattern  522  of the color filter  52  are formed by the same coating method that mentions in the first and the second embodiment. In other words, when the color film patterns are coated on the substrate, the second align pattern  521  and the fourth aligning pattern  522  are also coated on the substrate. 
   In the current embodiment, the first aligning pattern  511  and the third aligning pattern  512  are formed on the housing  51 , and these patterns  511 ,  512  are adjusted according to the style of the axis part  513  of the housing  51 . For example, as shown in  FIG. 8A , when the housing  51  is a disc-shaped housing, the first aligning pattern  511  and the third aligning pattern  512  may be formed on the surface of the housing  51  that contacts with the color filter  52 . However, when the housing  51  is a hat-shaped housing, the first aligning pattern  511  and the third aligning pattern  512  may only be formed on the surface of the housing  51  except the axis part  513  (i.e. outer part  514 ), as shown in  FIG. 8B . 
   Herein, the number, the size and the position of the aligning patterns  511 , 512 , 521  and  522  are adjusted according to practical needs. 
   Further, in step S 13 , the first aligning pattern  511  and the second aligning pattern  521  are aligned by an optical alignment. 
   As shown in  FIG. 9 , the color filter  52  and the housing  51  are assembled to creative a color wheel  5  in step S 14 . 
   The invention provides a coating method for the color filter and an aligning-assembling method for the color wheel, in both of which the optical alignment is used. Compared to the prior art, the accuracy of the alignment may be increased and the operational reliability of the color filter and the color wheel may also be increased. Further, the fabrication time of the color filter and the color wheel may be reduced. Moreover, the fabrication cost may also be reduced. In addition, the vibration and noise caused by the color wheel may be reduced. 
   The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.