Abstract:
A manufacturing process for forming a touch structure at least comprises the following steps. S1: a substrate is provided, a sensing region and a trace region surrounding the sensing region are defined on the substrate; S2: an electrode layer is formed on a substrate; S3: a first anti-etching optical layer is formed on the electrode layer; S4: the electrode layer that is not covered by the first anti-etching optical layer is etched; S5: a second anti-etching optical layer is formed on the first anti-etching optical layer and on the substrate; S6: the first anti-etching optical layer that is not covered by the second anti-etching optical layer is etched; and S7: a trace layer is formed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The disclosure relates to the touch sensing technology, and more particularly to touch panel structures and manufacturing processes thereof. 
         [0003]    2. Description of the Related Art 
         [0004]    In conventional touch electrode manufacturing processes, the main process comprises, forming electrode structures and forming traces, wherein a hard mask is used to define the pattern of the electrode structures and the pattern of the traces, which is removed after the process is performed. 
         [0005]    In order to provide a better display effect of a touch panel, an additional optical layer is formed on the touch structure, so as to adjust the display effect of the touch panel. 
         [0006]    Therefore, the conventional process is complicated, and needs additional processes to adjust the display effect of the touch panel. 
       SUMMARY OF THE INVENTION 
       [0007]    To solve the issue mentioned above, the present disclosure provides simplified manufacturing processes that also improve the display effect of the touch panel. 
         [0008]    The present disclosure provides a manufacturing process for forming a touch structure, at least comprising the following steps: 
         [0009]    S1: providing a substrate, wherein a sensing region and a trace region surrounding the sensing region are defined on the substrate; 
         [0010]    S2: forming an electrode layer on the substrate; 
         [0011]    S3: forming a first anti-etching optical layer on the electrode layer; 
         [0012]    S4: etching the electrode layer that is not covered by the first anti-etching optical layer, thereby dividing the electrode layer into an etched region and a non-etched region; 
         [0013]    S5: forming a second anti-etching optical layer on the first anti-etching optical layer and on the substrate, wherein the second anti-etching optical layer at least exposes pails of the first anti-etching optical layer within the trace region; 
         [0014]    S6: etching the first anti-etching optical layer that is not covered by the second anti-etching optical layer to expose the electrode layer of the non-etched region within the trace region; and 
         [0015]    S7: forming a trace layer disposed within the trace region, wherein the trace layer is electrically connected to the exposed electrode layer of the non-etched region. 
         [0016]    The present disclosure provides a touch panel comprising a substrate having a sensing region and a trace region surrounding the sensing region, an electrode layer, disposed on the substrate, wherein the electrode layer is divided into an etched region and a non-etched region, a first anti-etching optical layer, disposed on the electrode layer of the non-etched region, a second anti-etching optical layer, disposed on the first anti-etching optical layer and on the substrate, and at least parts of the electrode layer within the trace region is exposed by the first anti-etching optical layer and the second anti-etching optical layer, and a trace layer, disposed within the trace region, and electrically connected to the exposed electrode layer of the non-etched region. 
         [0017]    The refractive index of the first anti-etching optical layer and the refractive index of the second anti-etching optical layer can be adjusted, so that the display difference between the etched region and the non-etched region can be reduced. Compared to the conventional process, the present disclosure does not need the steps of removing the hard mask to define the electrode pattern and removing the hard mask to define the trace pattern, so the manufacturing process can be simplified, thereby improving the yield. 
         [0018]    These and other objectives of the present disclosure will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of at least the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a flow chart showing the manufacturing process of a touch structure according to various embodiments of the present disclosure. 
           [0020]      FIG. 2 a   - FIG. 2 h    are top views of a touch structure according to various embodiments of the present disclosure. 
           [0021]      FIG. 2 a   ′- FIG. 2   f′  are cross sectional views taken along the section line B-B′ of  FIG. 2 a   - FIG. 2   f.    
           [0022]      FIG. 2 g   ′- 1  and  FIG. 2 h   ′- 1  are cross sectional views taken along the section line B-B′ of  FIG. 2 g    and  FIG. 2 h    respectively. 
           [0023]      FIG. 2 g   ′- 1  and  FIG. 2 h   ′- 2  are cross sectional views taken along the section line C-C′ of  FIG. 2 g    and  FIG. 2 h    respectively. 
           [0024]      FIG. 2 i   ′- 1  and  FIG. 2 i   ′- 1  are cross sectional views of an etched region and a non-etched region of the touch structure respectively. 
           [0025]      FIG. 3 a   ˜ FIG. 3 c    are top views of as touch structure according to various embodiments of the present disclosure. 
           [0026]      FIG. 3 a   ′- 1 ,  FIG. 3 b   ′- 1  and  FIG. 3 c   ′- 1  are cross sectional views taken along the section line B-B′ of  FIG. 3   a,    FIG. 3 b    and  FIG. 3 c    respectively. 
           [0027]      FIG. 3 b   ′- 2  and  FIG. 3 c   ′- 1  are cross sectional views taken along the section line C-C′ of  FIG. 3 b    and  FIG. 3 c    respectively. 
           [0028]      FIG. 4 a   ˜ FIG. 4 c    are top views of a touch structure according to various embodiments of the present disclosure. 
           [0029]      FIG. 5  is a flow chart showing another manufacturing process of the touch structure according to some other embodiments of the present disclosure. 
           [0030]      FIG. 6 a    is a top view of a touch structure formed by the manufacturing process of  FIG. 5 . 
           [0031]      FIG. 6 a   ′- 1  is a cross sectional view taken along the section line B-B′ 
           [0032]      FIG. 6 a   ′- 2  is a cross sectional view taken along, the section line C-C′ of  FIG. 6   b.    
           [0033]      FIG. 7 a    is a top view of a touch display device comprising the touch structure of the present disclosure. 
           [0034]      FIG. 7 b    is a cross sectional view of  FIG. 7   a.    
           [0035]      FIG. 8 a    is a cross sectional view of a touch structure according to some other preferred embodiments of the present disclosure. 
           [0036]      FIG. 8 a    and  FIG. 8 c    are top views of the touch structure according to  FIG. 8 a    respectively. 
           [0037]      FIG. 9  is a cross sectional view of a touch device used the touch structure of  FIG. 8   a.    
           [0038]      FIG. 10  and  FIG. 11  show two different types of electrode layers of the touch structure of the present disclosure. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0039]      FIG. 1  is a flow chart showing a manufacturing process of a touch structure according to one or more preferred embodiments of the present disclosure. As shown in  FIG. 1 , the process comprises the following steps: 
         [0040]    S 101 : providing a substrate. Please refer to  FIG. 2 a    and  FIG. 2 a   . In some embodiments, the substrate  110  comprises glass or polyethylene terephthalate (PET). In some embodiments, the substrate  110  has a flat shape or a curved shape so as to be adapted to different types of touch panels. In some embodiments, the substrate  110  is a rigid substrate or a flexible substrate. The substrate  110  has a first surface S 1  and an opposite second surface S 2 . A sensing region A 1  (the region delimited by dot lines in  FIG. 2 a   ) and a trace, region A 2  surrounding the sensing region A 1  are defined on the substrate  110 . 
         [0041]    S 102 : forming an electrode layer on the substrate. Please refer to  FIG. 2 b   ′ and  FIG. 2 b   . An electrode layer  130   a  is formed on the first surface S 1  of the substrate  110 . The electrode layer  130   a  comprises silver nano-wires (SNW), carbon nano tubes (CNT), graphene, a conductive polymer, a metal oxide layer such as indium tin oxide (ITO), aluminum zinc oxide (AZO) or other transparent materials. In some embodiments, the electrode layer  130   a  is formed through a deposition process or a sputtering process. 
         [0042]    S 103 : forming a protection layer on the electrode layer. Please refer to  FIG. 2 c   ′ and  FIG. 2 e    showing a protection layer  140  formed on the electrode layer  130   a.  For sonic easily oxidized materials such as SNW, a protection layer  140  is formed to isolate the electrode layer  130   a  from being exposed to the air so as to improve the antioxidant capacity of the electrode layer  130   a.  In addition, since the SNW comprises some interspaces (voids), the protection layer  140  may be in contact with the substrate through these voids. In some embodiments, the SNW is bonded with the substrate  110  strongly by choosing a material with high adhesively to the substrate  110 . The material of the protection layer includes transparent materials such a silicon dioxide. The thickness of the protection layer is between 50 nm (nanometers) to 500 nm. 
         [0043]    S 104 : forming a first anti-etching optical layer on the protection layer. Please refer to  FIG. 2 d   ′ and  FIG. 2 d   . A first anti-etching optical layer  150  is formed on the protection layer  140 . The first anti-etching optical layer  150  is patterned to define the electrode pattern on the electrode layer  130   a.  The first anti-etching optical layer  150  includes acrylate polymer, epoxy resin or other transparent isolating materials. In some embodiments, the first anti-etching optical layer  150  is formed through a printing process. The thickness of the first anti-etching optical layer is between 0.05 μm (micrometers) to 5 μm. 
         [0044]    S 105 : etching the electrode layer that is not covered by the first anti-etching optical layer. The electrode layer is divided into an etched region and a non-etched region after the etching process. Please refer to  FIG. 2 e   ′ and  FIG. 2 e   . After the etching process is performed, an electrode layer  130   b  is divided into two parts: an etched region M and a non-etched region N. During the etching process, since the thickness of the protection layer  140  is thin enough, the etching solvent can penetrate the protection layer  140  and etch the electrode layer  130   a  within the etched region M. The electrode  130   b  shown in  FIG. 2 e   ′ and  FIG. 2 e    and the first anti-etching optical layer  150  have the same pattern. In some embodiments, the electrode structure includes a plurality of sensing electrodes arranged along a first direction, and each sensing electrode extends from a sensing region A 1  to a trace region A 2 . In some embodiments, the etching process for etching the electrode layer  130   a  is an incomplete etching process, i.e., only parts of the electrode layer  130   b  within the etched region M are etched, and the electrode layer  130   b  of the etched region M is electrically isolated from the electrode layer  130   b  of the non-etched region N. In order to avoid a color difference between the electrode layer of the etched region M and the electrode layer of the non-etched region N, in some other embodiments, the etching process is a complete etching process, but not limited thereto. 
         [0045]    S 106 : forming a second anti-etching optical layer, wherein the second anti-etching optical layer at least exposes parts of the first anti-etching optical layer disposed within the trace region. Please refer to  FIG. 2   f′  and  FIG. 2   f.  The second anti-etching optical layer  160  is formed on the first anti-etching optical layer  150  and on the protection layer  140 . The second anti-etching optical layer  160  is used to define a trace collection region of a trace layer (which will be formed in following steps). The second anti-etching optical layer  160  exposes parts of the first anti-etching optical layer  150  disposed within the trace region A 2 . The material of the second anti-etching optical layer  160  comprises acrylate polymer, epoxy resin or other transparent isolating materials. The thickness of the second anti-etching optical layer  160  is about from 0.05 μm to 5 μm. In some embodiments, the second anti-etching optical layer  160  can be formed through a printing process. 
         [0046]    S 107 : etching the first anti-etching optical layer and the protection layer that is not covered by the second anti-etching optical layer, to expose at least parts of the electrode layer of the non-etched region within the trace region. Please refer to  FIG. 2 g   ′- 1 .  FIG. 2 g   ′- 2  and  FIG. 2   g.  The first anti-etching optical layer  150  and the protection layer  140  that is not covered by the second anti-etching optical layer  160  are etched to expose parts of the electrode layer  130   b  of the non-etched region N 
         [0047]    S 108 : forming a trace layer. Please refer to  FIG. 2 h   ′- 1 ,  FIG. 2 h   ′- 2  and  FIG. 2 h   . A trace layer  170  is formed on the substrate  110  and is disposed within the trace region A 2 , wherein the trace layer  170  is electrically connected to the exposed electrode layer  130   b  of the non-etched region N. In some embodiments, one end of the trace layer  170  is electrically connected to each sensing electrode, and the other end of each trace layer  170  is collected into a trace collection region A 3 . It is worth noting that time amount and the size of the trace collection region A 3  can be adjusted, and is not limited to the amount and the size shown in the figure. The trace layer  170  within the trace collection region A 3  is electrically connected to an external controller (not shown) through a flexible circuit board, to analyze the signals transferred from the trace layer  170 . The trace layer  170  comprises transparent materials such as ITO, metals such as silver or aluminum, alloys of molybdenum., aluminum, or a composition thereof. 
         [0048]    Please refer to  FIG. 2 h   - 1 ,  FIG. 2 h   ′- 2  and  FIG. 2 h   . The touch structure mentioned above comprises: a substrate  110  having a sensing region A 1  and a trace region A 2  on it; an electrode layer  130   b,  disposed on the substrate  110 , and the electrode layer  130   b  is divided into an etched region M and a non-etched region N; a protection layer  140  disposed on the electrode layer  130   b  and on the substrate  110 ; a first anti-etching optical layer  150  disposed on the protection layer  140  within the non-etched region N; a second anti-etching optical layer  160 , which is disposed on the protection layer  140  and on the first anti-etching optical layer  150 . The protection layer  140 , the first anti-etching, optical layer  150  and the second anti-etching optical layer  160  expose parts of the electrode layer  130   b  of the non-etched region N within the trace region A 2 ; a trace layer  170 , disposed within the trace region A 2 , electrically connected to the exposed electrode layer  130   b  of the non-etched region N. In this embodiment, the trace layer  170  is disposed on the substrate  110 . The other components, material properties of the touch structure are described in detail in the manufacturing process mentioned above and will not be redundantly described here. 
         [0049]    Please refer to  FIG. 2 h   ′- 1 ,  FIG. 2 h   ′ 2 ,  FIG. 2 i   - 1  and  FIG. 2 i   - 2 . In the touch structure of the present disclosure, within the sensing region A 1 , the protection layer  140  and the second anti-etching, optical layer  160  are disposed on the electrode layer  130   b  within the etched region M, and the protection layer  140 , the first anti-etching optical layer  150 , the second anti-etching optical layer  160  are disposed on the electrode layer  130   b  within the non-etched region N. By adjusting the refractive index of the protection layer  140 , the refractive index of the first anti-etching optical layer  150  and the refractive index of the second anti-etching optical layer  160 , the display differences between the etched region M and the non-etched region N can be reduced, and ensure the touch structure of the present disclosure used as a touch device to achieve better display performance. In one or more preferred embodiments, the refractive index of the first anti-etching optical layer  150  is larger than the refractive index of the protection layer  140 , with an index difference at least larger than 0.1; the refractive index of the second anti-etching optical layer  160  is larger than the refractive index of the first anti-etching optical layer  150  with an index difference at least larger than 0.1. However, the refractive index of the protection layer  140 , the first anti-etching optical layer  150  and the second anti-etching optical layer  160  can be adjusted according to the different materials of the electrode layer. Besides, the thickness of the protection layer  140  is preferably comprised between 50 nm to 500 nm, which allows the electrode layer  130   a  to be easily penetrated when the etching process is performed. The thickness of the first anti-etching optical layer  150  and of the second anti-etching optical layer  160  is preferably comprised between 0.05 μm to 5 μm, which ensures a good optical transmittance of the touch structure, in addition, compared to the conventional manufacturing process, in the present disclosure, there are no steps for removing a hard mask used to define the electrode layer  130   a,  thereby simplifying the manufacturing process and increasing the yield. 
         [0050]    In some other embodiments of the present disclosure, a hollow region is formed on the second anti-etching optical layer, and a plurality of via holes disposed correspondingly to the hollow region are formed on the protection layer and on the first anti-etching optical layer; the trace layer is formed on the second anti-etching optical layer and is electrically connected to the exposed electrode layer of the non-etched region through the hollow region and through the via holes. Please refer to the following description: 
         [0051]    Please refer to  FIG. 3 a   ′and  FIG. 3   a.  The second anti-etching optical layer  160  which is formed in step S 106  comprises a hollow region  161  and the first anti-etching optical layer  150  within the trace region A 2  is exposed by the second anti-etching optical layer  160  through the hollow region  161 . In other words, within the trace region A 2 , the hollow region  161  exposes the first anti-etching optical layer  150  of each sensing electrode. 
         [0052]    Please refer to  FIG. 3 b   ′- 1   FIG. 3 b   ′- 2  and  FIG. 3 b   , wherein the same process is used to etch the first anti-etching optical layer  150  and the protection layer  140  within the hollow region  161 , and a plurality of via holes disposed correspondingly to the hollow region  161  are formed on the first anti-etching optical layer  150  and on the protection layer  140 . 
         [0053]    Please refer to  FIG. 3 c   ′- 1 ,  FIG. 3 c   ′- 2  and  FIG. 3 c   , wherein the same process is used as mentioned above. The trace layer  170  is formed within the trace region A 2 , wherein the trace layer  170  is formed on the second anti-etching optical layer  160  and is electrically connected to each sensing electrode through the hollow region  161  and through the via holes. Other characteristics are similar to those mentioned above, and will not be redundantly described here. 
         [0054]    Please refer to  FIG. 4 a    and  FIG. 4   b.  After the touch structure shown in step S 107  is formed (as shown in  FIG. 2 g    or  FIG. 3 a   ), a step for removing the second anti-etching optical layer  160  is selectively performed. In other words, in some embodiments, by adjusting only the refractive index of the protection layer  140  and the refractive index of the first anti-etching optical layer  150 , the display differences between the etched region M and the non-etched region N is reduced. 
         [0055]    Please refer to  FIG. 5 ,  FIG. 6 a   ,  FIG. 6 a   ′- 1  and  FIG. 6 a   ′- 2 .  FIG. 5  is a flow chart showing another manufacturing process of the touch structure according to some other embodiments of the present disclosure.  FIG. 6 a    is a top-view diagram showing a touch structure formed through the manufacturing, process of  FIG. 5 .  FIG. 6 a   ′- 1  is a cross sectional view taken along the section line B-B′ of  FIG. 6 a   .  FIG. 6 a   ′- 2  is a cross sectional view taken along the section line C-C′ of  FIG. 6 a   . The process comprises: step S 201 : providing a substrate; step S 102 : forming an electrode layer on the substrate. The difference between this embodiment and the process shown in  FIG. 1  is that the steps for forming the protection layer is skipped when the electrode layer is made of metal oxide such as ITO, AZO . . . , wherein these material have a better antioxidant capacity and a better adhesively. The first anti-etching optical layer is directly formed on the electrode layer step S 203 ). The electrode layer that is not covered by the first anti-etching optical layer is then etched (step S 204 ). A second anti-etching optical layer is then formed (step S 205 ), wherein the second anti-etching optical layer at least exposes pails of the first anti-etching, optical layer within the trace region. The first anti-etching optical layer that is not covered by the second anti-etching optical layer is then etched (step S 206 ) to expose the electrode layer of the non-etched region within the trace region. Finally, the trace layer is formed (step S 207 ). The other characteristics of this embodiment are similar to those of the embodiments shown in  FIG. 1 , and will not be redundantly described here. 
         [0056]    Please refer to  FIG. 6 a   ′- 1 ,  FIG. 6 a   ′- 2  and  FIG. 6   a.  The touch structure formed through the manufacturing process shown in  FIG. 5  comprises: a substrate  210  having a sensing region A 1  and a trace region A 2  thereon; a electrode layer  230   b  disposed on the substrate  210 , wherein the electrode layer  230   b  is divided into an etched region M and a non-etched region N; a first anti-etching optical layer  250  disposed on the electrode layer  230   b  within the non-etched region N; a second anti-etching, optical layer  260 , which is disposed on the substrate  210  and on the first anti-etching optical layer  250 . The first anti-etching optical layer  250  and the second anti-etching optical layer  260  expose parts of the electrode layer  230   b  of the non-etched region N within the trace region A 2  and a trace layer  270  disposed within the trace region A 2  is electrically connected to the exposed electrode layer  230   b  of the non-etched region N. In this embodiment, the trace layer  270  is disposed on the substrate  210 . In some other embodiments, a hollow region is formed on the second anti-etching optical layer  260 , a plurality of via holes disposed correspondingly to the hollow region is formed on the first anti-etching optical layer  250 , the trace layer  270  is electrically connected to the electrode layer  230   b  of the non-etched region N within the trace region A 2  through the hollow region and through the via holes. The other characteristics of this embodiment are similar to those of the embodiments mentioned above, and will not be redundantly described here. 
         [0057]    Please refer to  FIG. 7 a    and  FIG. 7   b.    FIG. 7 a    is a top-view diagram showing a touch display device comprising the touch structure of the present disclosure.  FIG. 7 b    is a cross sectional view of  FIG. 7   a.  In this embodiment, a touch display device  10  comprises: a display region A 4  and a decoration region A 5  surrounding the display region A 4 ; a cover lens  11 , a first touch structure  12 , a second touch structure  13  and a display module  14  are stacked in sequence. These components are combined to each other with an adhesive layer G. The cover lens  11  may have a flat shape or a curved shape so as to be adapted to different types of touch panels. In this embodiment, a shading layer  11   a  is formed on the surface that of the cover lens  11 , disposed on the same surface as the one the first touch structure  12  disposed on, and is disposed within the decoration region A 5 . The shading layer  11   a  comprises a hollow pattern, such as a bottom pattern or a logo trademark. In some other embodiments of the present disclosure, the shading layer  11   a  and the first touch structure  12  may disposed on different surfaces (in other words, the shading layer  11   a,  may disposed on the opposite surface of the cover lens  11 ), the shading layer  11   a  may comprise a color ink or a color photoresist layer. In addition, an anti-glare layer, a stain-resistant layer and other functional layers may be formed on another surface of the cover lens  11  (i.e. the opposite surface of the surface that the first touch structure  12  disposed on). The first touch structure  12  and the second touch structure  13  may comprise the touch structure described in the embodiments mentioned above, wherein the components  12   b  and  13   b  shown in figures are substrates; the components  12   a  and  13   a  shown in figures are the touch structure formed on the substrate. Preferably, the touch electrode of the first touch structure  12  and the touch electrode of the second touch structure  13  are perpendicular to each other. The shading layer  11   a  within the decoration region A 5  is used for hiding the traces of the first touch structure  12  and the second touch structure  13  within the trace region A 2 . The display module  14  can be a liquid crystal display module (LCD module) or other display panels. The adhesive layer G may include transparent adhesive layer, such as a solid optical clear adhesive or a liquid optical clear adhesive. In this embodiment, the adhesive layer G covers the whole surface of the cover lens  11 , but in some other embodiments of the present disclosure, the adhesive layer G may be disposed on partial regions only, such as disposed on the decoration region A 5  only. 
         [0058]    Please refer to  FIG. 8   a.    FIG. 8 a    is a cross sectional view showing a touch structure according to some other preferred embodiments of the present disclosure. After a touch structure is formed on the first surface S 1  of the substrate  110 , a manufacturing process shown in  FIG. 1  (or  FIG. 5 ) can be further performed to form another touch structure on the second surface S 2  of the substrate  110 . As shown in  FIG. 8 b    or  FIG. 8   c,  the touch structure formed on the second surface S 2  comprises a patterned electrode layer  230   b,  wherein the electrode layer  230   b  consists of a plurality of sensing electrodes arranged along a second direction. The other characteristics of the touch structure are similar to those of the embodiments mentioned above, and will not be redundantly described here. 
         [0059]    Please refer to  FIG. 9 ;  FIG. 9  is a cross sectional view showing a touch device using the touch structure of  FIG. 8 a   . A touch display device  20  comprises a cover lens  21 , a touch structure  22  and a display module  24  that are stacked in sequence. These components are combined to each other with an adhesive layer G. A shading layer  21   a  is formed surrounding the cover lens  21 ; the touch structure  22  comprises a substrate  22   b;  and a touch structure  22   a  and  22   c  are respectively formed on a first surface and on a second surface of the cover lens  21 . The other characteristics of the cover lens  21 , the shading layer  21   a,  the display module  24  and the adhesive layer G are similar to those of the touch device shown in  FIG. 7 b   , and will not be redundantly described here 
         [0060]    Please refer to  FIG. 10  and  FIG. 11 . The touch structure of the present disclosure further comprises other types and can be a single layer electrode structure, such as the symmetrical triangular structure as shown in  FIG. 10 , or a staggered comb-shaped structure as shown in  FIG. 11 . 
         [0061]    Compared to the conventional process, the present disclosure does not need the steps of removing the hard mask that defines the electrodes pattern and of removing the hard mask that defines the traces pattern, so the manufacturing process can be simplified, thereby improving the yield. Besides, the refractive index of the first anti-etching optical layer and the refractive index of the second anti-etching optical layer can be adjusted, so that the display difference between the etched region and the non-etched region can be reduced. 
         [0062]    Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may he made while retaining the teachings of the disclosure. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.