Patent Publication Number: US-2013227830-A1

Title: Manufacturing method of optical film and manufacturing method of stereoscopic display

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial no. 101107180, filed on Mar. 3, 2012. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a manufacturing method of a film and a manufacturing method of a display. More particularly, the invention relates to a manufacturing method of an optical film and a manufacturing method of a stereoscopic display. 
     2. Description of Related Art 
     In recent years, the continuing progress of display technologies leads to increasing demands on display quality of displays (e.g., image resolution, color saturation, and so on). However, other than the requirements for high resolution and high color saturation, in order to satisfy the need of users to watch real images, stereo displays which are capable of displaying stereo images have been developed. 
     The stereo displays can be roughly divided into a stereoscopic display which requires a user to wear a specially designed pair of glasses, and an auto-stereoscopic display which directly allows a user to watch an image with naked eyes. According to the operating principle of the stereoscopic display, left and right eye frames containing specific messages are sent by the display, and the eye glasses are applied to select the displayed left and right eye frames, so that the left and right eyes respectively observe left and right eye frames for generating a three-dimensional (3D) visual effect. According to a conventional stereo display technique, a patterned optical anisotropic film (patterned phase retardation film) is configured in a display to enable a display frame to be separated into a left-eye visible area and a right-eye visible area, and thereby the 3D display effect may be achieved. 
     At present, according to a method of forming a patterned phase retardation film, an optical film is formed on a substrate. An alignment solution is then coated onto the glass substrate and exposed twice to two polarized light with respective polarization directions, which results in secondary alignment of an optical alignment film. Thereafter, a liquid crystal material is coated to form the optical film capable of displaying a circular polarization image. However, since the secondary alignment force of the secondary exposure is weaker, which also deteriorates the image quality of the stereoscopic display using the patterned phase retardation film. As such, a user, when watching the image displayed on the stereoscopic display, may need to deal with a color shift issue. 
     SUMMARY OF THE INVENTION 
     The invention is directed to a manufacturing method of an optical film for accomplishing favorable secondary alignment. 
     The invention is further directed to a manufacturing method of a stereoscopic display for resolving a color shift issue of a stereo image. 
     In the invention, a manufacturing method of an optical film includes following steps. An alignment solution that includes a photo-polymerization alignment material is provided. The alignment solution is coated onto a first substrate which has a first area and a second area. The alignment solution on the first substrate is exposed to a polarized light, so as to form an optical alignment film on the first substrate. The optical alignment film on the first area has a first alignment direction, and the optical alignment film on the second area has a second alignment direction. A composite liquid crystal material that includes a reactive liquid crystal material and a monomer material is provided. The composite liquid crystal material is coated onto the optical alignment film that has the first alignment direction and the second alignment direction. A first non-polarized light having an absorption wavelength of the monomer material is provided, and the composite liquid crystal material on the optical alignment film is exposed to the first non-polarized light, such that the monomer material reacts with the reactive liquid crystal material. A second non-polarized light having an absorption wavelength of the reactive liquid crystal material is provided, and the reactive liquid crystal material on the optical alignment film is exposed to the second non-polarized light, such that the reactive liquid crystal material is solidified along the first alignment direction and the second alignment direction of the optical alignment film. 
     In the invention, another manufacturing method of an optical film includes following steps. A composite alignment solution that includes a photo-polymerization alignment material and a monomer material is provided. The composite alignment solution is coated onto a first substrate which has a first area and a second area. The composite alignment solution on the first substrate is exposed to a polarized light, so as to form an optical alignment film on the first substrate. The optical alignment film on the first area has a first alignment direction and the optical alignment film on the second area has a second alignment direction. A reactive liquid crystal material is provided. The reactive liquid crystal material is coated onto the optical alignment film that has the first alignment direction and the second alignment direction. A first non-polarized light having an absorption wavelength of the monomer material is provided, and the monomer material and the reactive liquid crystal material are exposed to the first non-polarized light, such that the monomer material reacts with the reactive liquid crystal material. A second non-polarized light having an absorption wavelength of the reactive liquid crystal material is provided, and the reactive liquid crystal material on the optical alignment film is exposed to the second non-polarized light, such that the reactive liquid crystal material is solidified along the first alignment direction and the second alignment direction of the optical alignment film. 
     According to an embodiment of the invention, a wavelength of the first non-polarized light ranges from 254 nm to 365 nm, and a wavelength of the second non-polarized light is 365 nm. 
     According to an embodiment of the invention, the monomer material absorption wavelength ranges from 311 nm to 320 nm. 
     According to an embodiment of the invention, the step of forming the optical alignment film having the first alignment direction and the second alignment direction on the first substrate includes the following. A photomask exposing the first area of the first substrate is provided. The alignment solution on the first area of the first substrate is exposed to a first polarized light of the polarized light, and the first polarized light passes through the photomask. Here, the first polarized light passing through the photomask and irradiating the first area polymerizes the photo-polymerization alignment material in the alignment solution, so as to define the first alignment direction. The alignment solution on the entire first substrate is exposed to a second polarized light of the polarized light. Here, the second polarized light has a polarization direction different from a polarization direction of the first polarized light, and the second polarized light polymerizes the photo-polymerization alignment material in the alignment solution on the second area, so as to define the second alignment direction. 
     According to another embodiment of the invention, the step of forming the optical alignment film having the first alignment direction and the second alignment direction on the first substrate includes the following. A photomask exposing the first area of the first substrate is provided. The composite alignment solution on the first area of the first substrate is exposed to a first polarized light of the polarized light, and the first polarized light passes through the photomask. Here, the first polarized light passing through the photomask and irradiating the first area polymerizes the photo-polymerization alignment material in the composite alignment solution, so as to define the first alignment direction. The composite alignment solution on the entire first substrate is exposed to a second polarized light of the polarized light. Here, the second polarized light has a polarization direction different from a polarization direction of the first polarized light, and the second polarized light polymerizes the photo-polymerization alignment material in the composite alignment solution on the second area, so as to define the second alignment direction. 
     According to an embodiment of the invention, the manufacturing method of the optical film further includes performing a pre-baking process on the alignment solution on the first substrate before the alignment solution on the first substrate is exposed to the polarized light. 
     According to an embodiment of the invention, the manufacturing method of the optical film further includes performing a pre-baking process on the composite liquid crystal material on the optical alignment film before the composite liquid crystal material on the optical alignment film is exposed to the first non-polarized light. 
     According to an embodiment of the invention, the manufacturing method of the optical film further includes performing a pre-baking process on the composite alignment solution on the first substrate before the composite alignment solution on the first substrate is exposed to the polarized light. 
     According to an embodiment of the invention, the manufacturing method of the optical film further includes performing a pre-baking process on the reactive liquid crystal material on the optical alignment film before the reactive liquid crystal material on the optical alignment film is exposed to the first non-polarized light. 
     In the invention, a manufacturing method of a stereoscopic display includes following steps. The optical film is formed on the first substrate according to the aforesaid manufacturing method of the optical film. A second substrate opposite to the first substrate of the optical film is provided. A liquid crystal layer is formed between the first substrate and the second substrate. 
     Based on the above, in the optical film described in the embodiments, the monomer material is doped into the photo-polymerization alignment material and/or the alignment solution. The monomer material is exposed to the polarized light to form networks on surfaces of the photo-polymerization alignment material and the reactive liquid crystal material. Thereby, the surface anchoring force of the secondary alignment and the alignment force of the reactive liquid crystal material can be enhanced. Namely, the issue of unfavorable secondary alignment can be resolved, and phase retardations at even or odd zones can be equalized. Moreover, owing to the arrangement of the optical film in the stereoscopic display, the color shift problem caused by unfavorable secondary alignment can be solved, and thus the quality of the stereo image can be ameliorated. 
     Several exemplary embodiments accompanied with figures are described in detail below to further describe the invention in details. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1A  to  FIG. 1I  are schematic side views illustrating a manufacturing process of an optical film according to an embodiment of the invention. 
         FIG. 2  is a schematic view illustrating alignment of a liquid crystal material according to a reference example. 
         FIG. 3  is a schematic view illustrating alignment of a reactive liquid crystal material according to the embodiment of the invention. 
         FIG. 4A  to  FIG. 4I  are schematic side views illustrating a manufacturing process of an optical film according to another embodiment of the invention. 
         FIG. 5  is a cross-sectional view illustrating a stereoscopic display according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS 
       FIG. 1A  to  FIG. 1I  are schematic side views illustrating a manufacturing process of an optical film according to an embodiment of the invention. 
     With reference to  FIG. 1A , an alignment solution  120  is coated onto a first substrate  110  which has a first area A 1  and a second area A 2 , and the first area A 1  and the second area A 2  are alternately arranged. In the present embodiment, the alignment solution  120  may be a photo-polymerization alignment material  120   a , but the present invention is not limited thereto. In addition, the alignment solution  120  may be coated onto the first substrate  110  by spin coating, slit coating, or in any other manner well known to people skilled in the art, and thus no further description is provided hereinafter. 
     With reference to  FIG. 1B , a pre-baking process B 1  is performed on the alignment solution  120 . Note that the temperature control and the time control of the pre-baking process B 1  pose an impact on the subsequent manufacturing processes; accordingly, the temperature and the time at which the pre-baking process B 1  is performed are determined by actual demands. In the present embodiment, the pre-baking process B 1  is performed at the temperature ranging from 90° C. to 150° C., for instance, and the pre-baking process B 1  is performed for 15˜30 minutes, for instance. 
     With reference to  FIG. 1C , a photomask  130  exposing the first area A 1  of the first substrate  110  is provided. The alignment solution  120  on the first area A 1  of the first substrate  110  is exposed to a first polarized light  142 , and the first polarized light  142  passes through the photomask  130 . At this time, the photo-polymerization alignment material  120   a  in the alignment solution  120  is irradiated by the first polarized light  142  and is thus polymerized, so as to define a first alignment direction D 1  on the first area A 1  of the first substrate  110 . 
     With reference to  FIG. 1D , the photomask  130  is removed, and the alignment solution  120  on the first substrate  110  is exposed to a second polarized light  144 . According to the present embodiment, the second polarized light  144 , for instance, irradiates the alignment solution  120  on the entire substrate  110 , for instance. At this time, the photo-polymerization alignment material  120   a  (shown in  FIG. 1C ) in the alignment solution  120  on the second area A 2  is irradiated by the second polarized light  144  and is thus polymerized, so as to define a second alignment direction D 2 . Note that the polarization direction of the second polarized light  144  is different from the polarization direction of the first polarized light  142 . Besides, in the present embodiment, the first polarized light  142  and the second polarized light  144  may be polarized ultraviolet light. So far, the fabrication of the optical alignment film  122  is initially completed, and the optical alignment film  122  has the first alignment direction D 1  on the first area A 1  and has the second alignment direction D 2  on the area A 2 . 
     With reference to  FIG. 1E , a composite liquid crystal material  150  is coated onto the optical alignment film  122  that has the first alignment direction D 1  and the second alignment direction D 2 . In the present embodiment, the composite liquid crystal material  150  includes a reactive liquid crystal material  150   a  and a monomer material M. To be more specific, the monomer material M may be a high polymer monomer, a low polymer monomer, a bifunctional monomer, a one-sided chain monomer, or a combination thereof. In the present embodiment, the monomer material M may be the compound represented by the following formulas (1)˜(7). 
     
       
         
         
             
             
         
       
     
     An absorption wavelength of the monomer material M ranges from 311 nm to 320 nm. In addition, the composite liquid crystal material  150  may be coated onto the first substrate  110  by spin coating, slit coating, or in any other manner well known to people skilled in the art, and thus no further description is provided hereinafter. 
     With reference to  FIG. 1F , a pre-baking process B 2  is performed on the composite liquid crystal material  150 . In the present embodiment, the pre-baking process B 2  is performed at the temperature ranging from 80° C. to 130° C., for instance, and the pre-baking process B 2  is performed for 30 seconds-1 minute, for instance. However, practically speaking, the temperature and the time at which the pre-baking process B 2  is performed are determined by actual demands, and thus the invention is not limited thereto. 
     With reference to  FIG. 1G , the composite liquid crystal material  150  is provided with a first non-polarized light  162  having the absorption wavelength of the monomer material M. In the present embodiment, a wavelength of the first non-polarized light  162  ranges from 254 nm to 365 nm, and the absorption wavelength of the monomer material M (ranging from 311 nm to 320 nm) falls within the wavelength range of the first non-polarized light  162 . Hence, when the composite liquid crystal material  150  on the optical alignment film  122  is exposed to the first non-polarized light  162 , the monomer material M absorbs the first non-polarized light  162  and then reacts with the reactive liquid crystal material  150   a.    
     In particular, after the monomer material M is exposed to the first non-polarized light  162 , networks (not shown in  FIG. 1G  but described below) are formed on surfaces of the photo-polymerization alignment material  120   a  and the reactive liquid crystal material  150   a , so as to enhance the surface anchoring force of the secondary alignment. Note that the reactive liquid crystal material  150   a  may be continuously stacked, and thus the alignment force of the reactive liquid crystal material  150   a  is enhanced together with the enhancement of the surface anchoring force of the secondary alignment. Thereby, after the reactive liquid crystal material  150   a  is arranged along the first and second alignment directions D 1  and D 2  of the optical alignment film  122 , equivalent alignment forces may be generated. 
     With reference to  FIG. 1H , a second non-polarized light  164  having an absorption wavelength of the reactive liquid crystal material  150   a  is provided. In the present embodiment, a wavelength of the second non-polarized light  164  is 365 nm, for instance. The reactive liquid crystal material  150   a  on the optical alignment film  122  is exposed to the second non-polarized light  164 , such that the reactive liquid crystal material  150   a  is solidified along the first alignment direction D 1  and the second alignment direction D 2  of the optical alignment film  122 . Thereby, a first alignment direction D 1 ′ and a second alignment direction D 2 ′ of the secondary alignment on the phase retardation film (not shown) can be defined. 
     With reference to  FIG. 1I , so far, the fabrication of the optical film  100  described in the present embodiment is completed, and the optical film  100  includes the first substrate  110 , the optical alignment film  122 , and a phase retardation film  152 . Besides, the phase retardation film  152  has the same alignment directions as the first and second alignment directions D 1  and D 2  of the optical alignment film  122 . Here, the first and second alignment directions D 1 ′ and D 2 ′ of the phase retardation film  152 , may transform the linear polarization light into a left-hand circular polarization light and a right-hand circular polarization light, for instance. 
     To be more specific, in the optical film  100 , the first alignment direction D 1  and the second alignment direction D 2  of the optical alignment film  122  define the direction along which the reactive liquid crystal material  150   a  is solidified. In addition, the monomer material M doped into the reactive liquid crystal material  150   a  is exposed to the first non-polarized light  162 , so as to enhance both the surface anchoring force of the secondary alignment and the alignment force of the reactive liquid crystal material  150   a . As such, after exposure to the second non-polarized light  164 , the alignment force along the second alignment direction D 2 ′ of the phase retardation film  152  may be equivalent to the alignment force along the first alignment direction D 1 ′. 
     The enhancement of both the surface anchoring force of the secondary alignment and the alignment force of the reactive liquid crystal material through the monomer material M in the optical film  100  described in the present embodiment will be further elaborated with reference to  FIG. 2  and  FIG. 3 . 
       FIG. 2  is a schematic view illustrating alignment of a liquid crystal material according to a reference example, and  FIG. 3  is a schematic view illustrating alignment of a reactive liquid crystal material according to the embodiment of the invention. Here,  FIG. 3  is a schematic view exemplarily illustrating the alignment taken along the sectional line A-A′ depicted in  FIG. 1I . 
     It should be mentioned that the structure provided in the reference example is similar to the structure described in the present embodiment. The difference therebetween lies in that the reactive liquid crystal material  150   a  in the reference example is not mixed with the monomer material M, while the composite liquid crystal material  150  described in the present embodiment includes the reactive liquid crystal material  150   a  and the monomer material M. With reference to  FIG. 2 , the first alignment direction D 1  is, for instance, from the upper-left corner to the lower-right corner, while the second alignment direction D 2  is, for instance, from the lower-left corner to the upper-right corner. In the reference example, the reactive liquid crystal material  150   a  is densely arranged along the first alignment direction D 1 , and the alignment result is rather satisfactory, which indicates that the alignment force along the first alignment direction D 1  is sufficient in the reference example. Nonetheless, the reactive liquid crystal material  150   a  is loosely arranged along the second alignment direction D 2 , and parts of the reactive liquid crystal material  150   a  cannot be arranged along the second alignment direction D 2 . In other words, the alignment force along the second alignment direction D 2  is insufficient according to the reference example, and thus issues of unsatisfactory alignment D (e.g., alignment defects D) may arise. 
     On the other hand, with reference to  FIG. 3 , in the composite liquid crystal material  150  described in the present embodiment, the monomer material M is mixed with the reactive liquid crystal material  150   a . Since the monomer material M is exposed to the non-polarized light, networks N are generated on the surfaces of the photo-polymerization alignment material and the reactive liquid crystal material  150   a . Thereby, the surface anchoring force of the secondary alignment and the alignment force of the reactive liquid crystal material can be enhanced. In conclusion, as shown in  FIG. 3 , the reactive liquid crystal material  150   a  is densely arranged along both the first alignment direction D 1 ′ and the second alignment direction D 2 ′, and the alignment result is rather satisfactory. Namely, according to the present embodiment, the alignment force along the second alignment direction D 2 ′ may be equivalent to the alignment force along the first alignment direction D′. Albeit the formation of the networks N along the first alignment direction D′, the networks N have limited effects because the alignment force along the first alignment direction D 1 ′ is sufficient. That is to say, the formation of the networks N mostly aims at enhancing the alignment force along the second alignment direction D 2 ′. 
     Additionally, the monomer material not only can be doped into the reactive liquid crystal material, as described above, but also can be doped into the alignment solution or into both the reactive liquid crystal material and the alignment solution according to other embodiments of the invention. According to the following embodiment shown in  FIG. 4A  to  FIG. 4I , the monomer material is doped into the alignment solution. 
       FIG. 4A  to  FIG. 4I  are schematic side views illustrating a manufacturing process of an optical film according to another embodiment of the invention. With reference to  FIG. 4A  to  FIG. 4I , the manufacturing process of the optical film  200  in the present embodiment is similar to that shown in  FIG. 1A  to  FIG. 1I , while the difference therebetween rests in that the composite alignment solution  120 ′ described in the step shown in  FIG. 4A  has both the photo-polymerization alignment material  120   a  and the monomer material M. Besides, in the step shown in  FIG. 4E , the film coated onto the optical alignment film  122 ′ does not contain the monomer material M but simply contains the reactive liquid crystal material  150 ′ (i.e., the reactive liquid crystal material  150   a ). 
     To be more specific, as shown in  FIG. 4A , the composite alignment solution  120 ′ that includes the photo-polymerization alignment material  120   a  and the monomer material M is coated onto the first substrate  110 . The first substrate  110  has a first area A 1  and a second area A 2 , and the first area A 1  and the second area A 2  are alternately arranged. The monomer material M described in the present embodiment is similar to that described in the previous embodiment, and the method of coating the composite alignment solution  120 ′ onto the first substrate  110  is similar to the method of coating the alignment solution  120  onto the first substrate  110  shown in  FIG. 1A . Hence, no further description is provided hereinafter. 
     With reference to  FIG. 4B , a pre-baking process B 1  is performed on the composite alignment solution  120 ′. Note that the temperature control and the time control of the pre-baking process B 1  pose an impact on the subsequent manufacturing processes; accordingly, the temperature and the time at which the pre-baking process B 1  is performed are determined by actual demands. In the present embodiment, the pre-baking process B 1  is performed at the temperature ranging from 90° C. to 150° C., for instance, and the pre-baking process B 1  is performed for 1530 minutes, for instance. 
     With reference to  FIG. 4C , a photomask  130  exposing the first area A 1  of the first substrate  110  is provided. The composite alignment solution  120 ′ on the first area A 1  of the first substrate  110  to a first polarized light  142 , and the first polarized light  142  passes through the photomask  130 . At this time, the photo-polymerization alignment material  120   a  in the composite alignment solution  120 ′ is irradiated by the first polarized light  142  and is thus polymerized, so as to define a first alignment direction D 1  on the first area A 1  of the first substrate  110 . 
     With reference to  FIG. 4D , the photomask  130  is removed, and the composite alignment solution  120 ′ on the first substrate  110  is exposed to a second polarized light  144 . According to the present embodiment, the second polarized light  144 , for instance, irradiates the composite alignment solution  120 ′ on the entire substrate  110 , for instance. At this time, the photo-polymerization alignment material  120   a  (shown in  FIG. 4C ) in the composite alignment solution  120 ′ on the second area A 2  is irradiated by the second polarized light  144  and is thus polymerized, so as to define a second alignment direction D 2 . Note that the polarization direction of the second polarized light  144  is different from the polarization direction of the first polarized light  142 . Besides, in the present embodiment, the first polarized light  142  and the second polarized light  144  may be polarized ultraviolet light. So far, the fabrication of the optical alignment film  122 ′ is initially completed, and the optical alignment film  122 ′ has the first alignment direction D 1  on the first area A 1  and has the second alignment direction D 2  on the area A 2 , respectively. 
     With reference to  FIG. 4E , a reactive liquid crystal material  150 ′ is coated onto the optical alignment film  122 ′ that has the first alignment direction D 1  and the second alignment direction D 2 . In the present embodiment, the monomer material M may be doped into the alignment solution to form the composite alignment solution  120 ′ (shown in  FIG. 4A ) instead of being doped into the reactive liquid crystal material  150 ′. However, the invention is not limited thereto, and the monomer material in other embodiments may be doped into both the alignment solution and the reactive liquid crystal material. Since the reactive liquid crystal material  150 ′ is coated onto the optical alignment film  122 ′ in a manner similar to that shown in  FIG. 1E , no further description is provided hereinafter. 
     With reference to  FIG. 4F , a pre-baking process B 2  is performed on the reactive liquid crystal material  150 ′. In the present embodiment, the pre-baking process B 2  is performed at the temperature ranging from 80° C. to 130° C., for instance, and the pre-baking process B 2  is performed for 30 seconds-1 minute, for instance. However, practically speaking, the temperature and the time at which the pre-baking process B 2  is performed are determined by actual demands, and thus the invention is not limited thereto. 
     With reference to  FIG. 4G , a first non-polarized light  162  having the absorption wavelength of the monomer material M is provided. Note that the reactive liquid crystal material  150 ′ described in the present embodiment is a transparent material. Accordingly, when the monomer material M is being exposed to the first non-polarized light  162 , the first non-polarized light  162  may pass through the reactive liquid crystal material  150 ′ and then irradiate the monomer material M (shown in  FIG. 4C ), such that the monomer material M in the present embodiment may be transformed into the networks N on the surfaces of the photo-polymerization alignment material (shown in  FIG. 4C ) and the reactive liquid crystal material  150 ′. Thereby, the surface anchoring force of the secondary alignment and the alignment force of the reactive liquid crystal material  150 ′ can be enhanced. 
     In particular, after the monomer material M is exposed to the first non-polarized light  162 , networks are formed on surfaces of the photo-polymerization alignment material and the reactive liquid crystal material  150 ′, so as to enhance the surface anchoring force of the secondary alignment. Note that the reactive liquid crystal material  150 ′ may be continuously stacked, and thus the alignment force of the reactive liquid crystal material  150 ′ is enhanced together with the enhancement of the surface anchoring force of the secondary alignment. Thereby, after the reactive liquid crystal material  150 ′ is arranged along the first and second alignment directions D 1  and D 2  on the optical alignment film  122 ′, equivalent alignment forces may be generated. 
     With reference to  FIG. 4H , a second non-polarized light  164  having an absorption wavelength of the reactive liquid crystal material  150 ′ is provided. In the present embodiment, a wavelength of the second non-polarized light  164  is 365 nm, for instance. The reactive liquid crystal material  150 ′ on the optical alignment film  122 ′ is exposed to the second non-polarized light  164 , such that the reactive liquid crystal material  150 ′ is solidified along the first alignment direction D 1  and the second alignment direction D 2  of the optical alignment film  122 ′. Thereby, a first alignment direction D 1 ′ and a second alignment direction D 2 ′ of the secondary alignment on the phase retardation film (not shown) can be defined. 
     With reference to  FIG. 4I , so far, the fabrication of the optical film  200  described in the present embodiment is completed, and the optical film  200  includes the first substrate  110 , the optical alignment film  122 ′, and a phase retardation film  152 . Besides, the phase retardation film  152  has the same alignment directions as the first and second alignment directions D 1  and D 2  of the optical alignment film  122 ′. Here, the first and second alignment directions D 1 ′ and D 2 ′ of the phase retardation film  152  may transform the linear polarization light into a left-hand circular polarization light and a right-hand circular polarization light, for instance. 
     To be more specific, in the optical film  200 , the first alignment direction D and the second alignment direction D 2  of the optical alignment film  122 ′ define the direction along which the reactive liquid crystal material  150 ′ is solidified. In addition, the monomer material M doped into the alignment solution is exposed by the first non-polarized light  162 , so as to enhance both the surface anchoring force of the secondary alignment and the alignment force of the reactive liquid crystal material  150 ′. As such, after exposure to the second non-polarized light  164 , the alignment force along the second alignment direction D 2 ′ of the phase retardation film  152  may be equivalent to the alignment force along the first alignment direction D 1 ′. 
     When the optical film  100  or  200  formed by performing said manufacturing process is actually applied, the optical film  100  or  200  may be employed in any stereoscopic display that displays images through phase retardation. An embodiment in this regard is provided hereinafter with reference to  FIG. 5 . 
       FIG. 5  is a cross-sectional view illustrating a stereoscopic display according to an embodiment of the invention. As shown in  FIG. 5 , in the stereoscopic display  500  of the present embodiment, an optical film  512  is formed on a first substrate  510  by performing the manufacturing method of the optical film  100  or  200  as described in the previous two embodiments. A second substrate  520  is then formed, and the second substrate  520  is opposite to the first substrate  510  on which the optical film  512  is formed. A liquid crystal layer  530  is formed between the first substrate  510  and the second substrate  520 . In the present embodiment, the first substrate  510  is a color filter substrate, for instance, and the second substrate  520  is an active device array substrate, for instance. Through the optical film  512  configured on the first substrate  510 , the stereoscopic display  500  is able to transform an incident light (not shown) into a left-hand circular polarization light and a right-hand circular polarization light, and thereby a user wearing a specially designed pair of glasses may watch a stereo image on the stereoscopic display  500 . 
     The optical film  512  of the stereoscopic display  500  described herein renders the alignment force along the second alignment direction and the alignment force along the first alignment direction equivalent. As such, the conventional color shift issue caused by unsatisfactory secondary alignment does not occur in the stereo image displayed on the stereoscopic display  500  That is to say, compared to the stereo image displayed on a conventional stereoscopic display, the stereo image displayed on the stereoscopic display  500  described in the present embodiment can have favorable quality. 
     To sum up, in the optical film described in the embodiments, the monomer material is doped into the photo-polymerization alignment material and/or the alignment solution. The monomer material is exposed to the polarized light to form networks on surfaces of the photo-polymerization alignment material and the reactive liquid crystal material. Since the reactive liquid crystal material may be continuously stacked, the alignment force of the reactive liquid crystal material can be enhanced after the surface anchoring force of the secondary alignment is enhanced by the networks, and phase retardation at even or odd zones can be equalized. Moreover, owing to the arrangement of the optical film in the stereoscopic display, the conventional color shift problem caused by unfavorable secondary alignment can be solved, and thus the quality of the stereo image can be ameliorated. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.