Abstract:
A touch display panel includes a display structure and a touch structure. The display structure includes pixels having a first pitch P 1 . The touch structure includes a touch layer having slits and dummy clefts. The slits and the dummy clefts have a second pitch P 2  and a third pitch P 3 , respectively. Two adjacent vertices of each slit define a line segment having a length Ly. 
     A first moire ratio (MR 1 ) defined as 
     
       
         
           
             
               P 
                
               
                   
               
                
               2 
             
             
               P 
                
               
                   
               
                
               1 
             
           
         
       
     
     satisfies: 20.7%×A 1 +8.5%×B 1 −3%≦MR 1 ≦12.7%×A 1 +16.5%×B 1 +3%, wherein A1 is an integer from 0 to 3, B1 is an integer from 1 to 3, and 0≦B 1 −A 1 ≦1. 
     A second moire ratio (MR 2 ) defined as 
     
       
         
           
             
               P 
                
               
                   
               
                
               3 
             
             
               P 
                
               
                   
               
                
               1 
             
           
         
       
     
     satisfies: 20.7%×A 2 +8.5%×B 2 −3%≦MR 2 ≦12.7%×A 2 +16.5%×B 2 +3%, wherein A 2  is an integer from 0 to 3, B 2  is an integer from 1 to 3, and 0≦B 2 −A 2 ≦1. 
     An arrangement ratio (LR) defined as 
     
       
         
           
             Ly 
             
               P 
                
               
                   
               
                
               1 
             
           
         
       
     
     satisfies: (2C+1)×25%−20%≦LR≦(2C+1)×25%+20%, wherein C is an integer from 0 to 11.

Description:
[0001]    This application claims the benefit of Taiwan application Serial No. 105106748, filed on Mar. 4, 2016, the disclosure of which is incorporated by reference herein in its entirety. 
       TECHNICAL FIELD 
       [0002]    The disclosure relates to a touch display panel. 
       BACKGROUND 
       [0003]    In order to make the operation more convenient and intuitive to the user, conventional display panels have been gradually replaced with touch display panels of which each includes a display structure and a touch structure. The touch display panels can be used in many fields such as navigation system, automatic teller machine, point of sale terminal, laptop and smartphone. However, the design of simply stacking the display structure and the touch structure cannot satisfy people&#39;s pursuit of better display and touch effects. Therefore, it is necessary to improve the matching relationship between the display structure and the touch structure of the touch display panel in all aspects. 
       SUMMARY 
       [0004]    The disclosure is directed to an improved touch display panel, particularly to the improvement in the matching relationship between the display structure and the touch structure of the touch display panel. 
         [0005]    According to some embodiments, a touch display panel includes a display structure and a touch structure. The display structure includes a plurality of pixels. The pixels have a first pitch P 1 . The touch structure includes a touch layer having a plurality of slits and a plurality of dummy clefts. Each slit has a plurality of vertices. The slits define a plurality of traces and a plurality of touch regions. The dummy clefts are disposed in the touch regions. The slits and the dummy clefts are substantially arranged along a first direction. The slits have a second pitch P 2  in the first direction. The dummy clefts have a third pitch P 3  in the first direction. The slits and the dummy clefts are arranged as a zigzag shape which substantially extends along a second direction. Two adjacent vertices of each slit define a line segment. The line segment has a first length Ly in the second direction. A first moire ratio MR 1  is defined as 
         [0000]    
       
         
           
             
               
                 P 
                  
                 
                     
                 
                  
                 2 
               
               
                 P 
                  
                 
                     
                 
                  
                 1 
               
             
             . 
           
         
       
     
         [0000]    The first moire ratio MR 1  substantially satisfies a formula (1): 
         [0000]      20.7%× A   1 +8.5%× B   1 −3%≦MR1≦12.7%× A   1 +16.5%× B   1 +3%  (1),
 
         [0000]    wherein A 1  is an integer from 0 to 3, B 1  is an integer from 1 to 3, and 0≦B 1 −A 1 ≦1. A second moire ratio MR 2  is defined as 
         [0000]    
       
         
           
             
               
                 P 
                  
                 
                     
                 
                  
                 3 
               
               
                 P 
                  
                 
                     
                 
                  
                 1 
               
             
             . 
           
         
       
     
         [0000]    The second moire ratio MR 2  substantially satisfies a formula (2): 
         [0000]      20.7%× A   2 +8.5%× B   2 −3%≦MR2≦12.7%× A   2 +16.5%× B   2 +3%  (2),
 
         [0000]    wherein A 2  is an integer from 0 to 3, B 2  is an integer from 1 to 3, and 0≦B 2 −A 2 ≦1. An arrangement ratio LR is defined as 
         [0000]    
       
         
           
             
               Ly 
               
                 P 
                  
                 
                     
                 
                  
                 1 
               
             
             . 
           
         
       
     
         [0000]    The arrangement ratio LR substantially satisfies a formula (3): 
         [0000]      (2 C+ 1)×25%−20%≦ LR ≦(2 C+ 1)×25%+20%  (3),
 
         [0000]    wherein C is an integer from 0 to 11. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIGS. 1 and 2  are schematic diagrams of a touch display panel of a touch display device according to disclosed embodiments. 
           [0007]      FIGS. 3A-3B  are schematic diagrams of a touch structure of a touch display panel according to disclosed embodiments. 
           [0008]      FIG. 4  is a schematic diagram showing the principles for choosing the pitches of the slits and the dummy clefts of a touch structure according to disclosed embodiments. 
           [0009]      FIGS. 5A-5D  are schematic diagrams showing the principles for choosing the pitches and the first length Ly for the slits and the dummy clefts of a touch structure according to disclosed embodiments. 
           [0010]      FIG. 6  is a schematic diagram showing the principles for further choosing the first length Ly of the slits and the dummy clefts of a touch structure according to disclosed embodiments. 
       
    
    
       [0011]    In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, it will be apparent that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
       DETAILED DESCRIPTION 
       [0012]    Detailed descriptions of the embodiments are made with reference to accompanying drawings. For clarity, elements shown in the figures may not reflect their actual sizes. Besides, some elements may be omitted from the figures. 
         [0013]    A touch display device includes a touch display panel. Detailed descriptions of the touch display panel according to the embodiments will be disclosed in the following paragraphs. The touch display device generally includes other elements (not shown in the figures) in addition to the touch display panel, such as a control circuit, or other elements used with the touch display panel like a backlight. To avoid the key points of the disclosure being confused, descriptions of such elements will not be particularly disclosed. 
         [0014]    Referring to  FIGS. 1 and 2 , a schematic diagram of a touch display panel  10  according to embodiments and a cross-sectional view of the touch display panel  10  are shown, respectively. The touch display panel  10  includes a display structure  100  and a touch structure  200 . 
         [0015]    According to some embodiments, the display structure  100  may be a liquid crystal display (LCD) structure, as shown in  FIGS. 1 and 2 . In other embodiments, the display structure may be a self-luminous organic light-emitting diode (OLED) display structure, a self-luminous inorganic light-emitting diode (LED) display structure, a reflective electronic paper display (EPD) display structure, or a Quantum Dot (QD) display structure. The display structure  100  typically includes a first substrate  102 , a second substrate  104 , and a display layer  106  between the first substrate  102  and the second substrate  104 . Specifically, the first substrate  102  may be a thin-film transistor substrate for inputting signals and controlling display images. The first substrate  102  includes a substrate  108  and a thin-film transistor layer  110 . The substrate  108  can comprise a transparent material such as glass, sapphire, plastic, resin or other transparent polymer materials. In other embodiments, if the penetrability is not required, the substrate  108  can comprise a non-transparent material such as metal, silicon or glass fiber. The thin-film transistor layer  110  includes circuits and elements such as thin-film transistors, scan lines, data lines, common signal lines, storage capacitors, pixel electrodes, common electrodes, and diodes. The scan lines and the data lines intersect and form a plurality of sub-pixels. Signal input of each sub-pixel can be independently controlled by a thin-film transistor. A number of sub-pixels can form a pixel  116  capable of displaying various gray levels and colors. The second substrate  104  may be a color filter substrate or a protection substrate. The second substrate  104  includes a substrate  112 , an electrode layer or a color filter layer  114 . A material of the substrate  112  can comprise a transparent material such as glass, sapphire, plastics, resin or other transparent polymer material. The color filter layer  114  includes various color filters capable of filtering the light into different colors. For example, the color filter layer  114  may include red (R), green (G), blue (B), white (W), or yellow (Y) filters corresponding to different sub-pixels. A plurality of color filters can be combined to display different gray levels and colors. In an embodiment, a pixel display unit can be formed of three sub-pixels corresponding to the RGB color filter layer  114 . In other embodiments, the pixel display unit can correspond to WRGB, RGBY, RG, GB, RB, or RRGGBB color filters. For example, referring to  FIG. 2 , the red sub-pixel R 1 , the green sub-pixel G 1  and the blue sub-pixel B 1  of a pixel as well as the red sub-pixel R 2 , the green sub-pixel G 2  and the blue sub-pixel B 2  of another pixel are shown. The pixel  116  has a first pitch P 1 , which refers to the width of the pixel  116 , or refers to the pitch between the geometric centers of the pixels  116 . For example, referring to  FIG. 2 , each of the pixels comprises three sub-pixels (ex. RGB), the first pitch P 1  can be calculated from the geometric center of a first red sub-pixel R 1  to that of a second red sub-pixel R 2 . In the present embodiment, the display layer  106  can be a liquid crystal layer, and the second substrate  104  has a color filter layer  114 . In other embodiments, the display layer  106  may be organic light-emitting diodes, inorganic light-emitting diodes, or other materials or elements, or a combination thereof. The second substrate  104  can be the substrate  112  only for covering or protecting, and does not have to include the color filter layer  114 . Alternatively, the second substrate  104  can have a color layer of quantum dots or other fluorescent or phosphorescent materials, and it&#39;s not limited to. It should be noted that the display structure  100  is not limited to the structure illustrated in  FIGS. 1 and 2 . For example, relative positions of the layers can be adjusted, and some layers can be added or removed. Alternatively, according to some other embodiments, the display structure  100  may be an LED display structure, an OLED display structure, or other suitable display structures. Regardless which display structure is used, the display structure includes a plurality of pixels  116  having a first pitch P 1 . 
         [0016]    The touch structure  200  may include a touch layer  202 . Detailed descriptions of the structural configuration of the touch structure  200  will be disclosed in the following paragraphs with reference to  FIGS. 3A-3B . The touch layer  202  may be a transparent electrode layer. The transparent electrode layer can comprise a transparent conductive oxide (TCO) such as indium tin oxide (ITO) or other suitable conductive materials like indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), zinc oxide (ZnO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO) or indium-doped molybdenum oxide (IMO), or metal films or metal traces having a thickness of nm level formed of gold (Au), silver (Ag), platinum (Pt), copper (Cu), aluminum (Al), titanium (Ti) or chromium (Cr) and the like. The transparent electrode layer can comprise a single-layer, a multi-layer, or a combination thereof. For example, the transparent electrode layer may be a singled-layered ITO film. Alternatively, the transparent electrode layer may be a multi-layer comprising an Ag film disposed between two IZO layers (IZO-Ag-IZO). The touch layer  202  may have a plurality of slits. The slits define a plurality of traces and a plurality of touch regions. The traces and the touch regions are electrically connected and used for signal transmission. The touch layer  202  may further have a plurality of dummy clefts disposed in the touch regions for improving the optical properties of the touch layer  202 . When the user touches a touch region, the touch region generates capacitance change, resistance change, voltage change or other suitable signal change in response to the user&#39;s touch. The generated changes are transmitted outwards through the traces. For example, when the touch structure  200  uses a mutual capacitive touch mode, the touch region may include a transmission sensing zone (Tx) and a reception sensing zone (Rx). The traces can transmit a touch transmission signal (Tx signal) and a touch reception signal (Rx signal) to the transmission sensing zone and the reception sensing zone, respectively. When the touch structure  200  uses the self-capacitive touch mode, the touch region is used as a touch detecting unit, and a touch reference signal and a touch sensing signal can be inputted or outputted with respect to the touch detecting unit. It should be noted that while the touch structure  200  shown in  FIGS. 1 and 2  is located above the display structure  100  (that is, the touch display panel adopts an on-cell touch design), the relative relationship between the display structure  100  and the touch structure  200  is not limited thereto. For example, the touch structure  200  and the display structure  100  can be integrated as one unit. For example, the touch display panel can adopt a hybrid in-cell touch design or an in-cell touch design, in which partial or entire structure of the touch structure  200  is disposed on the first substrate  102  and between the first substrate  102  and the second substrate  104 . In other embodiments, the touch structure  200  and the display structure  100  can be separated from each other. For example, the touch display panel can adopt an out-cell touch design in which the touch structure  200  and the second substrate  104  are separated by an interval. 
         [0017]    Referring to  FIGS. 3A-3B , schematic diagrams of a touch layer  202  according to some embodiments of the disclosure are shown, wherein  FIG. 3B  is an enlarged view of the region B in  FIG. 3A . The touch layer  202  may include trace regions  204  and touch regions  206 . Each trace region  204  includes a plurality of traces  208 . Each touch region  206  includes a transmission sensing zone  212  and a reception sensing zone  214 . The traces  208 , the transmission sensing zones  212 , and the reception sensing zones  214  are separated by the slits  210 . The dummy clefts  216  are disposed in the transmission sensing zones  212  and the reception sensing zones  214 . The dummy clefts  216  simulate the pattern of the slits  210 . Unlike the slits  210  which are used for dividing the traces  208 , the transmission sensing zones  212  or the reception sensing zones  214  into a plurality of independent entities, the dummy clefts  216  are used as openings. The slits  210  and the dummy clefts  216  are substantially arranged at an interval along a first direction D 1 . Here, the term “substantially” means that most of the slits  210  are arranged along the first direction D 1  at an interval except for a number of the slits  210  used for defining the traces  208  and the touch regions  206 . The slits  210  have a second pitch P 2  in the first direction D 1 . The second pitch P 2  is the distance between the centers of two adjacent slits  210  or the distance between the edges on the same side of two adjacent slits  210  in the first direction D 1 . For example, the second pitch P 2  is 42.6 μm. The dummy clefts  216  have a third pitch P 3  in the first direction D 1 . The third pitch P 3  is the distance between the centers of two adjacent dummy clefts  216  or the distance between the edges on the same side of two adjacent dummy clefts  216  in the first direction D 1 . The slits  210  and the dummy clefts  216  are arranged as a zigzag shape or a wave shape substantially extending along a second direction D 2  (which is, for example, perpendicular to the first direction D 1 ) to avoid moire phenomenon. Each slit  210  includes a plurality of vertices T. Vertices T are the vertex at which the zigzag or wavy line segments deflect. The line connecting two adjacent vertices T of the same slits  210  defines a line segment, which has a third length. The line segment has a second length Lx projected on the first direction D 1  and a first length Ly projected on the second direction D 2 . According to some embodiments, Lx is smaller than Ly. In other embodiments, Lx can be larger than or substantially equal to Ly. The slits  210  and the dummy clefts  216  can have substantially the same configuration pattern. For example, the slits  210  and the dummy clefts  216  substantially have the same width W, such as 6 μm. The slits  210  and the dummy clefts  216  may be different only in that the du rimy clefts  216  are discontinuous. The dummy clefts  216  have a fourth length smaller than the third length. The dummy clefts  216  are disconnected at the vertices T or other positions by a fifth length ΔLy, which is defined as a projection on the second direction D 2 . It should be noted that, in the present embodiment, the line segment defined by the vertices T is not equal to the section forming a dummy cleft  216 . Since the dummy clefts  216  are disconnected at the vertices T or other positions, the section forming the dummy cleft  216  is slightly shorter than the line segment. 
         [0018]    When the touch display panel displays black color, the visibility under various light sources will be affected by the structural configuration of the touch layer  202 . Specifically, if the third pitch P 3  of the dummy clefts  216  is much larger than the second pitch P 2  of the slits  210 , bright line group will be generated in the black background under the illumination of the light source due to the density difference between the slits and the dummy clefts. Besides, when the slits  210  and the dummy clefts  216  have a larger length Ly, bright fringes and dark fringes will be generated under the illumination of the light source because the zigzag shape comprises line segments in two different directions. The above phenomena can be resolved by adjusting the second pitch P 2  of the slits  210  and the third pitch P 3  of the dummy clefts  216  such that the density of the slits  210  and the density of the dummy clefts  216  can be closer to each other and by reducing the length Ly of the slits  210  and the dummy clefts  216  such that the zigzag shape can be closer to a straight line. However, such adjustment will easily lead to an exacerbation of the moire effect, particularly when the first pitch P 1  of the pixels  116  exactly falls in the first direction D 1  or the second direction D 2 . Therefore, the relationships among the first pitch P 1  and the second pitch P 2 , the third pitch P 3 , as well as the length Ly must satisfy certain conditions, such that the moire phenomenon can be avoided during an improvement of the visibility when the touch display panel displays black color. 
         [0019]    Firstly, a first moire ratio (first ratio) MR 1  is defined as 
         [0000]    
       
         
           
             
               
                 P 
                  
                 
                     
                 
                  
                 2 
               
               
                 P 
                  
                 
                     
                 
                  
                 1 
               
             
             . 
           
         
       
     
         [0000]    The first moire ratio MR 1  must substantially satisfy a formula (1): 
         [0000]      20.7%× A   1 +8.5%× B   1 −3%≦MR1≦12.7%× A   1 +16.5%× B   1 +3%  (1),
 
         [0000]    wherein A 1  is an integer from 0 to 3, B 1  is an integer from 1 to 3, and 0≦B 1 −A 1 ≦1. 
         [0020]    Next, a second moire ratio (second ratio) MR 2  is defined as 
         [0000]    
       
         
           
             
               
                 P 
                  
                 
                     
                 
                  
                 3 
               
               
                 P 
                  
                 
                     
                 
                  
                 1 
               
             
             . 
           
         
       
     
         [0000]    The second moire ratio MR 2  must substantially satisfy a formula (2): 
         [0000]      20.7%× A   2 +8.5%× B   2 −3%≦MR2≦12.7%× A   2 +16.5%× B   2 +3%  (2),
 
         [0000]    wherein A 2  is an integer from 0 to 3, B 2  is an integer from 1 to 3, and 0≦B 2 −A 2 ≦1. 
         [0021]    Then, an arrangement ratio LR is defined as 
         [0000]    
       
         
           
             
               Ly 
               
                 P 
                  
                 
                     
                 
                  
                 1 
               
             
             . 
           
         
       
     
         [0000]    The arrangement ratio LR must substantially satisfy a formula (3): 
         [0000]      (2 C+ 1)×25%−20%≦(2 C+ 1)×25%+20%  (3),
 
         [0000]    wherein C is an integer from 0 to 11. 
         [0022]    The second pitch P 2  and the third pitch P 3  may fall within the same range obtained when A 1 =A 2  and B 1 =B 2  to avoid the occurrence of bright lines caused by the density difference between the slits  210  and the dummy clefts  216 . In some embodiments, the second pitch P 2  is substantially equal to the third pitch P 3 . However, if the difference between the second pitch P 2  and the third pitch P 3  is not large enough to make the bright lines noticeable to human eyes, the situation that A 1 ≠A 2  and B 1 ≠B 2  is also acceptable. For example, the second pitch P 2  and the third pitch P 3  may satisfy: 0.66≦P 2 /P 3 ≦1.5. 
         [0023]    Principles of the above formulas are explained below. Referring to  FIG. 4 , it is found that the moire phenomenon is worst to the perception of Human Eyes when the Relationship with Respect to Multiples of ⅓ and ¼ exists between the second pitch P 2 , the third pitch P 3  and the first pitch P 1 . Therefore, the second pitch P 2 , the third pitch P 3  and the first pitch P 1  need to be adjusted to avoid such relationship. Thus, the range of the first moire ratio MR 1  is defined as 
         [0000]    
       
         
           
             
               
                 
                   1 
                   2 
                 
                  
                 
                   ( 
                   
                     
                       A 
                       3 
                     
                     + 
                     
                       B 
                       4 
                     
                   
                   ) 
                 
               
               ± 
               
                 C 
                  
                 
                     
                 
                  
                 % 
               
             
             , 
           
         
       
     
         [0000]    wherein A is an integer from 0 to 3, B is an integer from 1 to 3, and 0≦B−A≦1. Moreover, when B−A=1, let C=7, and when B−A=0, let C=3. The formulas (1) and (2) are thereby obtained by organizing the above expressions. Here, the term “substantially” relating the formulas means that the deviations due to the conversion from fraction number to decimal number is tolerable. 
         [0024]    Similarly, it is found that the moire phenomenon is worst to the perception of human eyes when the relationship with respect to multiples of ½ exists between the length Ly and the first pitch P 1 . Thus, the length Ly needs to be adjusted, such that the length Ly and the first pitch P 1  do not have such relationship. Thus, the range of the arrangement ratio LR can be defined and thereby the formula (3) is obtained. 
         [0025]      FIGS. 5A-5D  show the simulation results of MR (MR 1 , MR 2 ) and LR.  FIG. 5A  shows the simulation results obtained when the first pitch P 1  is substantially equal to 86.4 μm.  FIG. 5B  shows the simulation results obtained when the first pitch P 1  is substantially equal to 94.5 μm.  FIG. 50  shows the simulation results obtained when the first pitch P 1  is substantially equal to 117.5 μm.  FIG. 50  shows the simulation results obtained when the first pitch P 1  is substantially equal to 217.5 μm. The simulation results are acceptable if the reflection level is equal to or larger than 3. As shown in the figures, acceptable reflection level can be obtained when the above formulas are substantially satisfied. 
         [0026]    Referring to  FIG. 6 , the extreme values of the length Ly can be further determined.  FIG. 6  shows the relationship between the length Ly and the reflection level obtained when the second pitch P 2  and the third pitch P 3  are substantially equal to 70 μm and different light sources are used. The length Ly may be substantially equal to or smaller than or 160 μm in the case that the second pitch P 2  and the third pitch P 3  are substantially equal to 70 μm. 
         [0027]    It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.