Abstract:
A method for manufacturing a reflective coding plate is provided. The method includes steps of providing a first substrate, forming a mixture layer on the first substrate, providing a second substrate on the mixture layer and thereby a sandwich structure is formed, performing an orientation process on the sandwich structure, providing a mask having a code pattern thereon on one side of the sandwich structure, exposing the side of the sandwich structure to a UV light, removing the second substrate, and removing an unreacted part of the mixture layer.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a method for fabricating a touch panel, and more particularly, to a method for fabricating an optical sensor touch panel.  
       BACKGROUND OF THE INVENTION  
       [0002]     The optical sensor touch panel and the relevant techniques thereto are revealed in the recent days. Such a touch panel has a matrix composed of light sources and detectors therein and the position of the input touch is detected via sensing the optical image. When an input touch is provided to the touch panel, the light from the light source would be obstructed and hence the detector corresponding thereto would not receive the signal. If the position which the detector does not receive the signal is determined, the position of the input touch would be identified accordingly.  
         [0003]     Moreover, another kind of optical sensor touch panel is operated with an optical sensor pen, which includes a light transmitter and a light detector therein. The light transmitter of the optical sensor pen would transmit a light to the touch panel having a code pattern and the light detector would receive the light reflected therefrom. When the optical image is determined via the code pattern, the position of the input touch is able to be identified. Such a touch panel achieves the input detection in a short distance and has a great reflectivity which is beneficial to be integrated in a liquid crystal display (LCD) panel.  
         [0004]     The optical sensor touch panel and the LCD panel are typically fabricated from the liquid crystal (LC). The cholesteric liquid crystal (CLC) substance has a similar spiral structure as the cholesteric molecules for the biomedical applications. The CLC substance has the optical activity, the ability for selectively optical-scattering and the dichroism for circular polarization, and moreover, the reflectivity for the lights having the similar optical activity is up to 50%. Therefore, the CLC substance is applied in several optical components for the LCD. The spontaneous alignment method for manufacturing the cholesteric reflective polarizer is disclosed in U.S. Pat. No. 6,721,030, wherein a lamination process is performed on the photopolymerized CLC substance, so that the photopolymerized CLC substance is oriented in a specific orientation for being a polarizer. Moreover, the coloring medium composed of the CLC microflake is disclosed in U.S. Pat. No. 6,753,044. The disclosed coloring medium has an improved brightness and color characteristics.  
         [0005]     Based on the above discussions, for further taking advantage of the CLC substance, a method for manufacturing a coding plate for the optical touch panel is provided in the present invention. The coding plate is fabricated from the novel material, CLC substance, and is integrated into the LCD panel, so as to provide an input panel. The coding plate of the present invention has a great reflectivity, so that the optical performance of the input panel is maintained. Furthermore, the code pattern of the coding plate is also well protected thereby.  
       SUMMARY OF THE INVENTION  
       [0006]     In accordance with a first aspect of the present invention, a method for manufacturing a reflective coding plate is provided. The method includes steps of providing a first substrate, forming a mixture layer on the first substrate, providing a second substrate on the mixture layer and thereby a sandwich structure is formed, performing an orientation process on the sandwich structure, providing a mask having a code pattern thereon on one side of the sandwich structure, exposing the side of the sandwich structure to a UV light, removing the second substrate; and removing an unreacted part of the mixture layer.  
         [0007]     Preferably, the mixture layer comprises a cholesteric liquid crystal substance and an initiator.  
         [0008]     In accordance with a second aspect of the present invention, a method for manufacturing a reflective coding plate is provided. The method includes steps of providing a first substrate, forming a first orientation film on the first substrate and performing a rubbing process thereon, forming a mixture layer on the first substrate which is rubbed, providing a second substrate on the mixture layer and thereby a sandwich structure is formed, performing a heat treatment process on the sandwich structure so that the cholesteric liquid crystal substance is oriented thereby, providing a mask having a code pattern thereon on one side of the sandwich structure, exposing the side of the sandwich structure to a UV light, removing the second substrate, and removing an unreacted part of the mixture layer.  
         [0009]     Preferably, the mixture layer comprises a cholesteric liquid crystal substance and an initiator.  
         [0010]     In accordance with a third aspect of the present invention, a method for manufacturing a reflective coding plate is provided. The method includes steps of providing a first substrate, forming a structure with a mixture layer on the first substrate, providing a mask having a code pattern thereon on one side of said structure, exposing the side of said structure to a UV light, and removing an unreacted part of the mixture layer.  
         [0011]     Preferably, the mixture layer comprises a cholesteric liquid crystal substance and an initiator.  
         [0012]     Furthermore, a pitch length of the cholesteric liquid crystal substance multiplied by an average refractive index of the cholesteric liquid crystal substance in foregoing inventions is in an infrared ray wavelength range between 700 nm to 1700 nm.  
         [0013]     The foregoing and other features and advantages of the present invention will be more clearly understood through the following descriptions with reference to the drawings, wherein: 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  and FIGS.  2 ( a ) to ( h ) are diagrams illustrating the method for manufacturing a reflective coding plate according to a first preferred embodiment of the present invention;  
         [0015]      FIG. 3  and FIGS.  4 ( a ) to ( h ) are diagrams illustrating the method for manufacturing a reflective coding plate according to a second preferred embodiment of the present invention; and  
         [0016]      FIG. 5  is a diagram schematically illustrating the code pattern applied in the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]     The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only; it is not intended to be exhaustive or to be limited to the precise form disclosed.  
         [0018]     Please refer to  FIG. 1  and FIGS.  2 ( a ) to ( h ), which are diagrams illustrating the method for manufacturing a reflective coding plate according to a first preferred embodiment of the present invention. First, a first substrate  201  is provided as shown in the step  11  in  FIG. 1  and in  FIG. 2 ( a ), and the first substrate  201  may be a TAC (Triacetate Cellulose) film. Second, the mixture layer  202 , which is composed of a CLC (Cholesteric Liquid Crystal) substance and an initiator, is applied to the first substrate  201  via the slot die, the spin coating or the roll coating as shown in the step  12  in  FIG. 1  and in  FIG. 2 ( b ), wherein the composition ratio of the CLC substance to the initiator is 99%:1%. The mixture layer  202  is subsequently covered with a second substrate  203 , so that a sandwich structure  204  is formed as shown in the step  13  and in  FIG. 2 ( c ). Moreover, the second substrate  203  may be also a TAC film.  
         [0019]     The sandwich structure  204  is oriented by a provided lamination apparatus  205  as shown in the step  14  in  FIG. 1  and in  FIG. 2 ( d ). The lamination apparatus  205  provides a shear stress to the sandwich structure  204 , so that the CLC substance therein is oriented. Then, a mask  206  having a code pattern thereon is provided on one side of the sandwich structure  204  as shown in the step  15  in  FIG. 1  and in  FIG. 2 ( e ), and the side of the sandwich structure  204  is subsequently exposed to a energetic irradiation including UV light as shown in the step  16  in  FIG. 1  and in  FIG. 2 ( f ).  
         [0020]     The CLC substance in the mixture layer  202  is photopolymerized while being exposed to the UV light. When the UV light illuminates the mixture layer  202  through the mask  206 , thereby one portion of the CLC substance is exposed to the UV light, and the other portion is shielded thereoff. The exposed portion of the CLC substance is photopolymerized, and hence the CLC polymer film  202 ′ composed of the photopolymerized CLC polymer  2021 ′ and the unphotopolymerized CLC substance  2022 ′ is formed as shown in  FIG. 2 ( g ).  
         [0021]     Then, the second substrate  203  is removed as shown in the step  17  in  FIG. 1 , and afterward, the unphotopolymerized CLC substance  2022 ′ is washed and cleaned as shown in the step  18  in  FIG. 1 . A coding layer  207  composed of the photopolymerized CLC polymer  2021 ′ and hence a reflective coding plate  208  having the coding layer  207  are formed as shown in  FIG. 2 ( h ).  
         [0022]     Please refer to  FIG. 3  and FIGS.  4 ( a ) to ( h ), which are diagrams illustrating the method for manufacturing a reflective coding plate according to a second preferred embodiment of the present invention. First, a first substrate  401  is provided as shown in the step  31  in  FIG. 3  and in  FIG. 4 ( a ), and the first substrate  401  may be a LCD (Liquid Crystal Display) panel, which has a color filter, but no polarizer attached thereon. Second, the color filter of the first substrate  401  is covered with an orientation film  402 , and has a rubbing process via a roller  403  performed thereon, so that the first substrate  401  is oriented thereby as shown in the step  32  in  FIG. 3  and in  FIG. 4 ( b ). Then, the mixture layer  404 , which is composed of a CLC (Cholesteric Liquid Crystal) substance and an initiator, is applied to the first substrate  401  and the orientation film  402  via the slot die, the spin coating or the roll coating as shown in the step  33  in  FIG. 3  and in  FIG. 4 ( c ), wherein the composition ratio of the CLC substance to the initiator is 99%:1%.  
         [0023]     Similarly, the mixture layer  404  is subsequently covered with a second substrate  405 , so that a sandwich structure  406  is formed as shown in the step  34  in  FIG. 3  and in  FIG. 4 ( d ). Moreover, the second substrate  405  is a glass substrate, which also has an orientation film thereon and is oriented via the rubbing process. The sandwich structure  406  is annealed as the step  35  in  FIG. 3 , so that the CLC substance of the mixture layer  404  is oriented and arranged thereby. A mask  407  having a code pattern thereon is subsequently provided on one side of the sandwich structure  406  as shown in the step  36  in  FIG. 3  and in  FIG. 4 ( e ), and then the side of the sandwich structure  406  is exposed to a energetic irradiation including UV light as shown in the step  37  in  FIG. 3  and in  FIG. 4 ( f ).  
         [0024]     The CLC substance in the mixture layer  406  is photopolymerized while being exposed to the UV light. When the UV light illuminates the mixture layer  406  through the mask  407 , thereby one portion of the CLC substance is exposed to the UV light, and the other portion is shielded thereoff. The exposed portion of the CLC substance is photopolymerized, and hence the CLC polymer film  404 ′ composed of the photopolymerized CLC polymer  4041 ′ and the unphotopolymerized CLC substance  4042 ′ is formed as shown in  FIG. 4 ( g ).  
         [0025]     Then, the second substrate  405  is removed as shown in the step  38  in  FIG. 3 , and afterward the unphotopolymerized CLC substance  4042 ′ is washed and cleaned as shown in the step  39  in  FIG. 3 . A coding layer  408  composed of the photopolymerized CLC polymer  4041 ′ and hence a reflective coding plate  409  having the coding layer  408  are formed as shown in  FIG. 4 ( h ).  
         [0026]     Please refer to  FIG. 5 , which is a diagram schematically illustrating the typical code pattern applied in the present invention. The code pattern configured on the mask includes plural pattern units  51 , which are arranged in columns and rows. In this case of the present invention, the pattern unit  51  is a circle having a diameter of D. The distance between the center of the circle and that of the adjacent one is a constant C 1 , which equals to 4 times of D, and the distance between two adjacent rows is also a constant C 2  equaled to 3½ D. Furthermore, the diameter D is ranged in 5 to 100 μm.  
         [0027]     According to the preferred embodiments of the present invention, the reflective coding plate is provided for the optical sensor touch panel which is suitable for sensing an infrared ray. Therefore, it is preferred that the pitch length of the CLC substance multiplied by the average refractive index thereof which is the wavelength of a light is ranged from 700 to 300,000 nm, especially from 700 to 1700 nm. Certainly, a value of 910 nm is the most preferable since the infrared ray exactly has a wavelength of 910 nm.  
         [0028]     Since the photopolymerized CLC substance has a specific optical activity and a spiral structure, the light transmitted therethrough is separated into a left and a right circular polarized light and 50% of the light having the similar rotation is reflected thereby. Therefore, the CLC reflective coding plate of the present invention is able to precisely detect the reflective light and has an excellent performance. Such a provided CLC reflective coding plate is further integrated into the LCD panel, so as to fabricate an input panel therefrom. Moreover, the code for the coding plate is well protected by means of the present invention. Hence, the present invention not only has novelty and progressiveness, but also has an industry utility.  
         [0029]     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.