Patent Publication Number: US-2017371189-A1

Title: Display panel

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 15/335,596, filed on Oct. 27, 2016, which claims the priority of Taiwan Patent Application No. 104135560, filed on Oct. 28, 2015, the disclosure of which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     Field of the Invention 
     The present disclosure relates to an electronic device, and more particularly to an electronic display panel with non-rectangular shape and a method for processing the display panel. 
     Description of the Related Art 
     An electronic display is an optoelectronic device that is able to transfer electric signals into visible images so that human beings can see the information contained in the electronic signals. Recently, liquid-crystal displays, organic electro luminescence displays and light-emitting diode display have grown in popularity. 
     Because of their slimness, low power consumption and low radiation, these image-display devices have been widely used in portable electronic devices such as TV, desktop computers, notebook computers, tablet, and mobile phones, and are even gradually replacing cathode ray tube (CRT) monitors and conventional TVs. 
     SUMMARY 
     In accordance with some embodiments of the disclosure, a display panel is provided. The display panel includes a first substrate and a second substrate. The first substrate has a display area and the second substrate is arranged opposite to the first substrate. The display panel further includes a display layer. The display layer is positioned between the first substrate and the second substrate. The display panel also includes a sealant. The sealant is positioned between the first substrate and the second substrate and located outside the display area. The sealant has an outline, and at least a portion of the outline is wavy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the embodiments and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings. 
         FIG. 1  shows a cross-sectional view of a display panel, in accordance with some embodiments. 
         FIG. 2  shows a top view of a portion of elements of a display panel, in accordance with some embodiments. 
         FIG. 3  shows a schematic view explaining a definition of a manufacturing variance and a definition of a pitch between node centers, in accordance with some embodiments. 
         FIG. 4  shows a flow chart of a method for applying a curved segment of a sealant, in accordance with some embodiments. 
         FIG. 5  shows an enlarged view of a region in  FIG. 2  near an intersection point  112 , in accordance with some embodiments. 
         FIG. 6  shows a flow chart of a method for applying a curved segment of a sealant, in accordance with some embodiments. 
         FIG. 7  shows an enlarged view of a region in  FIG. 2  near an intersection point  114 , in accordance with some embodiments. 
         FIG. 8  shows a schematic view of a sealant, in accordance with some embodiments. 
         FIG. 9  shows an image of a display panel observed with a microscope, in accordance with some embodiments. 
         FIG. 10  shows an image of a display panel observed with a microscope, in accordance with some embodiments. 
         FIG. 11  shows a schematic view of a display panel, in accordance with some embodiments. 
         FIG. 12  shows an image of a display panel observed with a microscope, in accordance with some embodiments. 
     
    
    
     DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS 
     The display panel of the present disclosure is described in detail in the following description. In the following detailed description, for purposes of explanation, numerous specific details and embodiments are set forth in order to provide a thorough understanding of the present disclosure. The specific elements and configurations described in the following detailed description are set forth in order to clearly describe the present disclosure. It will be apparent, however, that the exemplary embodiments set forth herein are used merely for the purpose of illustration, and the inventive concept may be embodied in various forms without being limited to those exemplary embodiments. In addition, the drawings of different embodiments may use like and/or corresponding numerals to denote like and/or corresponding elements in order to clearly describe the present disclosure. However, the use of like and/or corresponding numerals in the drawings of different embodiments does not suggest any correlation between different embodiments. Furthermore, the attached drawings may be drawn in a slightly simplified or exaggerated way for ease of understanding; the numbers, shapes and dimensional scales of elements depicted may not be exactly the same as those in practical implementation and are not intended to limit the present disclosure. 
     It should be noted that the elements or devices in the drawings of the present disclosure may be present in any form or configuration known to those skilled in the art. In addition, the expression “a layer overlying another layer”, “a layer is disposed above another layer”, “a layer is disposed on another layer” and “a layer is disposed over another layer” may indicate not only that the layer directly contacts the other layer, but also that the layer does not directly contact the other layer, there being one or more intermediate layers disposed between the layer and the other layer. 
     In this specification, relative expressions are used. For example, “lower”, “bottom”, “higher” or “top” are used to describe the position of one element relative to another. It should be appreciated that if a device is flipped upside down, an element at a “lower” side will become an element at a “higher” side. 
     The terms “about” and “substantially” typically mean +/−20% of the stated value, more typically +/−10% of the stated value and even more typically +/−5% of the stated value. The stated value of the present disclosure is an approximate value. When there is no specific description, the stated value includes the meaning of “about” or “substantially”. 
       FIG. 1  shows a cross-sectional view of a display panel  1 , in accordance with some embodiments. In some embodiments, the display panel  1  includes a first substrate  10 , a second substrate  20 , a display layer  30 , and a sealant  40 . The elements of the display panel  1  can be added or omitted, and the disclosure should not be limited by the embodiment. The first substrate  10  and the second substrate  20  may be a rigid substrate or a flexible substrate. The rigid substrate may comprise but not limit to glass, sapphire or ceramic. The flexible substrate may comprise polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), or other suitable organic materials. The display layer  30  may be liquid crystal, organic light-emitting diode, or light emitting diode. 
     The display panel  1  may be a liquid-crystal panel, such as thin film transistor panel. Alternatively, the display panel  1  may be a twisted nematic (TN) mode liquid-crystal panel, a vertical aligned (VA) mode liquid-crystal panel, an in-plane switching (IPS) mode liquid-crystal panel, a fringe field switching (FFS) mode liquid-crystal panel, a cholesteric mode liquid-crystal panel, a blue phase in-plane switching (IPS) mode liquid-crystal panel, or another suitable liquid-crystal panel. The display panel  1  may be an organic light-emitting diode (OLED) panel, a light-emitting diode (LED) panel, a micro light-emitting diode (micro LED) panel and a quantum dot (QD) panel. 
     In some embodiments, the second substrate  20  is spaced apart from the first substrate  10  by a distance and covers the first substrate  10 . The display layer  30  is positioned between the first substrate  10  and the second substrate  20 . The display layer  30  is operated according to electronic signals from the driving unit (not shown in figures) so as to show images. The first substrate  10  may be a thin film transistor (TFT) substrate and include a number of pixels and switching elements. The second substrate  20  may be a color filter substrate or a transparent cover substrate. The first substrate  10  or the second substrate  20  may be equipped with touch functionality. 
     The sealant  40  is connected between the first substrate  10  and the second substrate  20 . The sealant  40  may surround the display layer  30 . Or, the sealant  40  may not surround the display layer  30  but may be applied neighboring a portion of the display layer  30 . In one embodiment, the sealant  40  is applied on the first substrate  10  (or the second substrate  20 ) along a path with a rectangular shape or non-rectangular shape. The path is defined according to the shape of the outer edge of the first substrate  10  (or the second substrate  20 ). Alternatively, the path is defined according to the shape of the display area AA. In one embodiment, the sealant  40  is applied between an edge of the first substrate  10  and an edge of the display area AA. In other words, the sealant  40  is applied on a non-display area. In one embodiment, the non-display area is located between an edge of the first substrate  10  and an edge of the display area AA. In one embodiment, the display area AA is an area where display elements for display images are positioned. 
       FIG. 2  shows a top view of a portion of the display panel  1 , in accordance with some embodiments. In one embodiment, the first substrate  10  is not rectangular, and it includes a number of lateral edges  111 ,  113 , and  115  which are consecutively connected to one another. The lateral edge  111  connects to the lateral edge  113  via an intersection point  112 , and the lateral edge  113  connects to the lateral edge  115  via an intersection point  114 . In the embodiment shown in  FIG. 2 , the included angle formed by the two lateral edges  111  and  113  is larger than the included angle formed by the two lateral edges  113  and  115 . In one embodiment, the two lateral edges  113  and  115  are straight, and the included angle is an angle less than 180 degree. 
     In one embodiment, the sealant  40  is applied on the first substrate  10  along a path with a non-rectangular shape. The path includes a number of straight paths (such as first straight path st 1 , second straight path st 2 , and third straight path st 3 ) and a number of curved paths (such as first curved path ct 1  and second curved path ct 2 ). 
     Specifically, during the process of forming the sealant  40 , a first straight segment  41  is formed on the first substrate  10  along the first straight path st 1 , wherein the first straight path st 1  is parallel to the lateral edge  111  and spaced apart from the lateral edge  111  by a distance. Afterwards, a curved segment  42  is formed on the first substrate  10  along the first curved path ct 1  which is adjacent to the intersection point  112 . It should be understood that a “straight segment” means that this segment of the sealant is formed on a substrate along a straight path. Therefore, its shape is substantially straight. Considering the sealant is fluid, the straight segment may also be called a substantially straight segment. 
     Afterwards, a second straight segment  43  is formed on the first substrate  10  along the second straight path st 2 , wherein the second straight path st 2  is parallel to the lateral edge  113  and spaced apart from the lateral edge  113  by a distance. Afterwards, a curved segment  44  is formed on the first substrate  10  along the second curved path ct 2  which is adjacent to the intersection point  114 . Afterwards, a third straight segment  45  is formed on the first substrate  10  along the third straight path st 3 , wherein the third straight path st 3  is parallel to the lateral edge  115  and spaced apart from the lateral edge  115  by a distance. 
     The distance between the first, second, and third straight paths st 1 , st 2 , st 3  and their corresponding lateral edges  111 ,  113 , and  115  may be the same or different. As shown in  FIG. 2 , a circle (shown in right hand side of  FIG. 2 ) is tangential to the first straight path st 1  and the second straight path st 2 , wherein the first curved path ct 1  is an arc of the circle, and the rotation radius r 1  of the curved path ct 1  equals to the radius of the circle. In addition, a circle (shown in left hand side of  FIG. 2 ) is tangential to the second straight path st 2  and the third straight path st 3 , wherein the second curved path ct 2  is an arc of the circle, and the rotation radius r 2  of the curved path ct 2  equals to the radius of the circle. In other words, the rotation radius of a curved path is equal to the radius of curvature of the curved path. 
     During the process of applying the sealant  40  over the first and the second curved paths ct 1  and ct 2 , the movement of a nozzle  70  for applying the sealant  40  is controlled by a controller (such as robot arm, not shown in the figures). However, in some embodiments of the disclosure, the nozzle  70  is not moved along the first and the second curved paths ct 1  and ct 2  precisely. On the contrary, the nozzle  70  is moved along multiple straight lines, and each straight line is connected by two neighboring nodes on the first curved paths ct 1  or the second curved path ct 2 . Additionally, during the movement of the nozzle  70  along a straight line between two neighboring nodes, the nozzle  70  moves with acceleration that varies. Details of the method for moving the nozzle will be described in the descriptions regarding to the embodiments shown in  FIGS. 5 and 7 . By controlling the movement of the nozzle  70  among the nodes, the sealant  40  is applied on the first substrate  10  with high efficiency. On the other hand, the manufacturing time required for producing the display panel  1  is reduced. 
     In the following description, the maximum distance between the straight line connecting two neighboring nodes and its corresponding curved path is defined as a manufacturing variance. In one embodiment, the curved path is an arc. The arc of a circle is constructed by three of the nodes. However, the method of constructing a circle is not limited to the above mentioned method. In the process of applying the sealant  40  over the same curved path, with the increase of the number of nodes, the manufacturing variance is decreased and the shape of the curved segment is highly compatible with the curved path. In this case, a longer manufacturing time is required. On the contrary, with the decrease of the number of nodes, the manufacturing variance is increased and the shape of the curved segment is roughly compatible with the curved path. In this case, however, the sealant  40  can be applied with a shorter manufacturing time. 
     Therefore, as shown in  FIG. 3 , the curved path ct has a rotation radius r. By applying an infinite number of nodes on the curved path ct, a manufacturing variance for applying the sealant would be approximately zero. On the other hand, by applying a finite number of nodes on the curved path ct, a manufacturing variance for applying the sealant would be approximately μ. Then, according to the trigonometry, we can get the following equation: 
       0&lt; r−r  cos(θ/2)≦μ
 
     Then, we define the shortest distance between two neighboring nodes is a distance D. If the manufacturing variance is zero, the distance D would be zero. If the manufacturing variance is μ, according to the trigonometry, the distance D can be calculated from the following equations: 
     
       
         
           
             
               
                 
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     According to the above result, we can conclude that, under a fixed manufacturing variance, the distance D is greater when the rotation radius r is greater. In other words, the distance D may be approximately proportional to the square root of the rotation radius r: 
     
       
      
       D∝√{square root over (r)} 
      
     
     Based on the above relationship, during the manufacturing of the same display panel, if the manufacturing variance is fixed, a larger rotation radius r of the curved path makes a larger distance D. 
     In one embodiment, a manufacturing variance μ is given, the distance D may satisfy the following equation: 
       0&lt; D≦ 2μ√{square root over ((2 r −μ))}
 
     In one embodiment, a minimum manufacturing variance μ 1  is given and a maximum manufacturing variance μ 2  is given, the distance D may satisfy the following equation: 
       2√{square root over (μ 1 (2 r−μ   1 ))}&lt; D≦ 2√{square root over (μ 2 (2 r−μ   2 ))}
 
     However, the manufacturing variance may be varied in different regions of the non-display area of the display panel. Therefore, under a variable manufacturing variance, a larger rotation radius r does not necessarily result in a larger distance D. 
     In some embodiments, to avoid the display area AA being affected by the curved segment of the sealant, or to avoid the sealant leaking outside of the first substrate  10 , the manufacturing variance for applying the curved segment of the sealant  40  is determined based on the distance d between the display area AA and the edge of the substrate. For example, as shown in  FIG. 2 , the lateral edge  111  of the display panel  1  is spaced apart from the edge  120  of the display area AA by a distance d 1 , and the lateral edge  115  of the display panel  1  is spaced apart from the edge  120  of the display area AA by a distance d 2 , wherein the distance d 2  is equals to the distance d 1 . Therefore, the manufacturing variance for applying the curved segment  42  of the sealant  40  is substantially the same as the manufacturing variance for applying the curved segment  44  of the sealant  40 . In some embodiments, a sealant comprises multiple curved segments and the one curved segment having the biggest rotation radius r may satisfy the above equation. 
     In some embodiments, the manufacturing variance for applying the curved segment of the sealant equals to the distance d between the lateral edge of the substrate and the edge of the display area AA. Or, the value of the manufacturing variance may be adjusted according to different requirements of the display panel. For example, the manufacturing variance may be 10 μm, 50 μm, 100 μm, 150 μm, or 200 μm, but the disclosure should not be limited thereto. According to the preset manufacturing variance, the operator determines the number of node for applying the sealant on the corresponding curved path. In cases where the distance d between the lateral edge of the substrate and the edge of the display area AA is selected as the manufacturing variance, the distance D between two neighboring nodes may satisfy the following equation: 
       0&lt; D≦ 2√{square root over ( d (2 r−d ))}
 
     In one embodiment, a minimum manufacturing variance is 10 μm and a maximum manufacturing variance is 200 μm. Then, the distance D satisfies the following range: 
       2√{square root over (10(2 r− 10))}≦ D≦ 2√{square root over (200(2 r− 200))}
 
     wherein r and D in unit of micrometer 
       FIG. 4  is a flow chart illustrating a method  5  for applying the curved segment  42  of the sealant  40 , in accordance with some embodiments. For illustration, the flow chart will be described along with the schematic views shown in  FIG. 5 . Some of the steps described in  FIG. 4  can be replaced or eliminated for different embodiments. 
     Method  5  for applying the curved segment  42  of the sealant  40  is described below: 
     The method  5  begins with step  50 , in which sealant material is applied by the nozzle  70 . In step  51  the speed of the nozzle  70  is decreased with a negative acceleration a 1 . In addition, as shown in  FIG. 5 , the nozzle  70  is moved from an initial point n 0  of the curved segment  42  to a node na 1  at the first curved path ct 1  which is immediately adjacent to the initial point n 0 . During this process, sealant material is continuously supplied from the nozzle  70  and is applied on the first substrate  10 , and the speed of the nozzle  70  gradually decreases from a preset speed V 0  at which the nozzle  70  is moved to apply the straight segment  41 . As a result, the width of the sealant gradually increases to width B. In some embodiments, when the nozzle  70  reaches the node na 1 , the speed of the nozzle  70  is 0. In some embodiments, when the nozzle  70  reaches the node na 1 , the speed of the nozzle  70  is still greater than 0. 
     In some embodiments, before applying the curved segment  42 , the nozzle  70  is moved along the first straight path st 1  at the preset speed V 0 , and the sealant material is supplied from the nozzle  70  at a fixed flow rate to form the straight segment  41  of the sealant  40  on the first substrate  10 , wherein the width of the straight segment  41  of the sealant  40  is A. In some embodiments, the nozzle  70  is moved from the initial point n 0  of the curved segment  42  to the node na 1  along the first straight path st 1 . 
     In step  52 , the speed of the nozzle  70  is increased with a positive acceleration a 2 . In addition, as shown in  FIG. 5 , the nozzle  70  is moved from the node na 1  to a middle point of a straight line S 1  between the node na 1  and the node na 2 . During this process, sealant material is continuously supplied from the nozzle  70  and is applied on the first substrate  10 , and the speed of the nozzle  70  gradually increases. As a result, the width of the sealant gradually decreases to width C. 
     In some embodiments, the nozzle  70  reaches the middle point of the straight line S 1  at speed V 1 , and the speed V 1  is greater than the speed V 0  at which the nozzle  70  is moved to apply the straight segment  41 . Alternatively, the nozzle  70  reaches the middle point of the straight line S 1  at speed V 1 , and the speed V 1  is less than the speed V 0  at which the nozzle  70  is moved to apply the straight segment  41 . Alternatively, the nozzle  70  reaches the middle point of the straight line S 1  at speed V 1 , and the speed V 1  equals to the speed V 0  at which the nozzle  70  is moved to apply the straight segment  41 . In some embodiments, the step  52  terminates as the nozzle  70  reaches a position behind or ahead of the middle point of the straight line S 1 . 
     In step  53 , the speed of the nozzle  70  is decreased with a negative acceleration a 3 . In addition, as shown in  FIG. 5 , the nozzle  70  is moved from the middle point of the straight line S 1  to the node na 2  along the straight line S 1 . During this process, sealant material is continuously supplied from the nozzle  70  and is applied on the first substrate  10 , and the speed of the nozzle  70  gradually decreases. As a result, the width of the sealant gradually increases again. 
     In some embodiments, the nozzle  70  is moved at the acceleration a 1  and the acceleration a 3  for the same time period, and the acceleration a 1  equals to the acceleration a 3 . Therefore, the sealant at the node na 2  has the same width B as the sealant at the node na 1 ; however, the disclosure should not be limited thereto. In some other embodiments, the acceleration a 1  is different from the acceleration a 3 , and thus the width of the sealant  40  at the node na 1  is different from the width of sealant at the node na 2 . 
     Afterwards, the sealant material is applied on the first substrate  10  along a straight line between the nodes na 2  and na 3 , and along a straight line between the nodes na 3  and na 4 , and along a straight line between the nodes na 4  and na 5  by the method similar to the steps  52  and  53 . 
     In step  54 , the speed of the nozzle  70  is increased with a positive acceleration a 2 . In addition, as shown in  FIG. 5 , the nozzle  70  is moved from the node na 5  to an end point n 1  of the curved segment  42  along the second straight path st 2 . During this process, sealant material is continuously supplied from the nozzle  70  and is applied on the first substrate  10 , and the speed of the nozzle  70  gradually increases. As a result, the width of the sealant gradually decreases. In some embodiments, the step  54  is not stopped until the speed of the nozzle  70  is increased to the preset speed V 0  at which the nozzle  70  is moved to apply the straight segment  41 . 
     In the above-mentioned embodiments, the nodes na 1 -na 5  are separated by the same distance D 1 , and the distance D between the two neighboring node centers may satisfy the following equation: 
       0&lt; D   1 ≦2√{square root over (μ 1 (2 r   1 −μ 1 ))}
 
     where r 1  is the rotation radius of the first curved path ct 1 , μ 1  is the manufacturing variance utilized for applying the curved segment  42 . In one embodiment, If the manufacturing variance μ 1  is substituted with the distance d 1  between the lateral edge  111  of the substrate and the edge of the display area AA, the distance D 1  may satisfy the following equation: 
       0&lt; D   1 ≦2√{square root over ( d   1 (2 r   1   −d   1 ))}
 
     In one embodiment, If the manufacturing variance μ 1  is substituted with the distance 200 μm, the distance D 1  may satisfy the following equation: 
       0&lt; D   1 ≦2√{square root over (200(2 r   1 −200))}
 
     wherein r 1  and D 1  in unit of micrometer 
     Further, If a minimum manufacturing variance is substituted with the distance 10 μm, the distance D 1  may satisfy the following equation: 
       2√{square root over (10(2 r   1 −10))}&lt; D   1 ≦2√{square root over (200(2 r   1 −200))}
 
     wherein r 1  and D 1  in unit of micrometer 
     In some embodiments, the curved segment  42  defines one sealant node  421  at each of the nodes na 1 -na 5 . Each of the sealant nodes  421  is located within a range of a circle-like shape and the width of each sealant node  421  changes in a narrow-wide-narrow manner. For example, as shown in  FIG. 5 , the width of the sealant node  421  changes in a A-B-C manner, wherein the width B is greater than the width A as well as the width C. The centers of the sealant nodes  421  are respectively located at the nodes na 1 -na 5 , and the radius of the sealant node  421  is smaller than 0.5 times of the distance D 1 . In addition, the curved segment  42  defines a connection portion  423  between the two neighboring nodes  421 . The sealant node  421  has a larger width of B and the connection portion  423  has a smaller width of C. The width B is greater than the width A of the straight segment  41 , and the width A of the straight segment  41  is greater than or equals to the width C of the connection portion  423 . In some embodiments, the widths A, B, and C are respectively measured in a direction perpendicular to the first curved path ct 1 . 
       FIG. 6  is a flow chart illustrating a method  6  for applying the curved segment  44  of the sealant  40 , in accordance with some embodiments. For illustration, the flow chart will be described along with the schematic views shown in  FIG. 7 . Some of the steps described in  FIG. 6  can be replaced or eliminated for different embodiments. 
     Method  6  for applying the curved segment  44  of the sealant  40  is described below: 
     The method  6  begins with step  60 , in which sealant material is applied by the nozzle  70 . In step  61 , the speed of the nozzle  70  is decreased with a negative acceleration a 1 . In addition, as shown in  FIG. 7 , the nozzle  70  is moved from an initial point n 2  of the curved segment  44  to a node nb 1  at the second curved path ct 2  which is immediately adjacent to the initial point n 2 . During this process, sealant material is continuously supplied from the nozzle  70  and is applied on the first substrate  10 , and the speed of the nozzle  70  gradually decreases from a preset speed V 0  at which the nozzle  70  is moved to apply the straight segment  43 . As a result, the width of the sealant gradually increases to width B. In some embodiments, when the nozzle  70  reaches the node nb 1 , the speed of the nozzle  70  is 0. In some embodiments, when the nozzle  70  reaches the node nb 1 , the speed of the nozzle  70  is still greater than 0. 
     In some embodiments, before applying the curved segment  44 , the nozzle  70  is moved along the second straight path st 2  at the preset speed V 0 , and the sealant material is supplied from the nozzle  70  in a fixed flow rate to form the straight segment  43  of the sealant  40  on the first substrate  10 , wherein the width of the straight segment  43  of the sealant  40  is A. In some embodiments, the nozzle  70  is moved from the initial point n 2  of the curved segment  44  to the node nb 1  along the second straight path st 2 . 
     In step  62 , the speed of the nozzle  70  is increased with a positive acceleration a 2 . In addition, as shown in  FIG. 7 , the nozzle  70  is moved from the node nb 1  to a middle point of a straight line S 2  between the node nb 1  and the node nb 2 . During this process, sealant material is continuously supplied from the nozzle  70  and is applied on the first substrate  10 , and the speed of the nozzle  70  gradually increases. As a result, the width of the sealant gradually decreases to width D. 
     In some embodiments, the nozzle  70  reaches the middle point of the straight line S 2  at speed V 2 , and the speed V 2  is greater than the speed V 0  at which the nozzle  70  is moved to apply the straight segment  43 . Alternatively, the nozzle  70  reaches the middle point of the straight line S 2  at speed V 2 , and the speed V 2  equals to the speed V 0  at which the nozzle  70  is moved to apply the straight segment  43 . Alternatively, the nozzle  70  reaches the middle point of the straight line S 2  at speed V 2 , and the speed V 2  is less than the speed V 0  at which the nozzle  70  is moved to apply the straight segment  41 . In some embodiments, the step  62  terminates as the nozzle  70  reaches a position behind or ahead of the middle point of the straight line S 2 . 
     In step  63 , the speed of the nozzle  70  is decreased with a negative acceleration a 3 . In addition, as shown in  FIG. 7 , the nozzle  70  is moved from the middle point of the straight line S 2  to the node nb 2  along the straight line S 2 . During this process, sealant material is continuously supplied from the nozzle  70  and is applied on the first substrate  10 , and the speed of the nozzle  70  gradually decreases. As a result, the width of the sealant gradually increases again. 
     In some embodiments, the nozzle  70  is moved at the acceleration a 1  and the acceleration a 3  for the same time period, and the acceleration a 1  equals to the acceleration a 3 . Therefore, the sealant at the node nb 2  has the same width B as the sealant at the node nb 1 ; however, the disclosure should not be limited thereto. In some other embodiments, the acceleration a 1  is different from the acceleration a 3 , and thus the width of sealant at the node nb 1  is different from the width of the sealant at the node nb 2 . 
     Afterwards, the sealant material is applied on the first substrate  10  along a straight line between the nodes nb 2  and nb 3 , and along a straight line between the nodes nb 3  and nb 4 , and along a straight line between the nodes nb 4  and nb 5  by the method similar to the steps  62  and  63 . 
     In step  64 , the speed of the nozzle  70  is increased with a positive acceleration a 2 . In addition, as shown in  FIG. 7 , the nozzle  70  is moved from the node nb 5  to an end point n 3  of the curved segment  44  along the third straight path st 3 . During this process, sealant material is continuously supplied from the nozzle  70  and is applied on the first substrate  10 , and the speed of the nozzle  70  gradually increases. As a result, the width of the sealant gradually decreases. In some embodiments, the step  64  is not stopped until the speed of the nozzle  70  is increased to the preset speed V 0  at which the nozzle  70  is moved to apply the straight segment  43 . 
     In the above-mentioned embodiments, the nodes nb 1 -nb 5  are separated by the same distance D 2 , and the distance D 2  between the two neighboring node may satisfy the following equation: 
       0&lt; D   2 ≦2√{square root over (μ 2 (2 r   2 −μ 2 ))}
 
     where r 2  is the rotation radius of the second curved path ct 2 , μ 2  is the manufacturing variance utilized for applying the curved segment  44 . If the manufacturing variance μ 2  is substituted with the distance d 2  between the lateral edge  115  of the substrate and the edge of the display area AA, the distance D 2  may satisfy the following equation: 
       0&lt; D   2 ≦2√{square root over ( d   2 (2 r   2   −d   2 ))}
 
     In one embodiment, If the manufacturing variance μ 2  is substituted with the distance 200 μm, the distance D 2  may satisfy the following equation: 
       0&lt; D   2 ≦2√{square root over (200(2 r   2 −200))}
 
     wherein r 2  and D 2  in unit of micrometer 
     In some embodiments, the curved segment  44  defines one sealant node  441  at each of the nodes nb 1 -nb 5 . Each of the sealant nodes  441  is located within a range of a circle-like shape and the width of each sealant node  441  changes in a narrow-wide-narrow manner. The centers of the sealant nodes  441  are respectively located at the nodes na 1 -na 5 , and the radius of the sealant nodes  441  is smaller than 0.5 times of the distance D 2 . In addition, the curved segment  44  defines an overlapping portion  443  at which the two neighboring sealant nodes  441  overlap. The sealant node  441  has a larger width B and the overlapping portion  443  has a smaller width D. The width B is greater than the width A of the straight segment  41 . The width A of the straight segment  41  is smaller than the width D. In some embodiments, the width A of the straight segment  41  is equal to or larger than the width D. In some embodiments, the widths A, B, and D are measured in a direction perpendicular to the second curved path ct 2 . 
     Referring to  FIG. 2  and with reference to  FIGS. 4 and 6 , in some embodiments, the manufacturing variances for applying the first curved segment  42  and the second curved segment  44  are assumed to be the same value. Therefore, according to the following equation: 
     
       
      
       D∝√{square root over (r)} 
      
     
     The rotation radius r 2  of the second curved path ct 2  is smaller than the rotation radius r 1  of the first curved path ct 1 , so the distance D 2  between two neighboring sealant nodes  441  is smaller than the distance D 1  between two neighboring sealant nodes  421 . Namely, under the same manufacturing variance, the rotation radius r 1  and the rotation radius r 2  may satisfy the relation of 0&lt;r 2 /r 1 &lt;1, and the distance D 1  and the distance D 2  may satisfy the relation of 0&lt;D 2 /D 1 &lt;1. 
       FIG. 8  shows a schematic view of the sealant  40 , in accordance with some embodiments. In some embodiments, the sealant  40  further includes a curved segment  46 . The curved segment  46  includes a number of sealant nodes  461 , and the sealant nodes  461  have their node nc 1 -nc 5  arranged on a third curved path ct 3 . In addition, the curved segment  46  includes a number of connection portions  463  positioned between the two neighboring sealant nodes  461 . 
     In some embodiments, the maximum distance between the outer edge  4612  of the sealant node  461  (i.e., an edge of the sealant node  461  which is away from the display area AA) and the third curved path ct 3 , is greater than the maximum distance between the inner edge  4614  of the sealant node  461  (i.e., an edge of the sealant node  461  which is close to the display area AA) and the third curved path ct 3 . 
     Specifically, as shown in  FIG. 8 , the outer edge  4612  the sealant node  461  includes a first end point p 1 , a second end point p 2 , and a third end point p 3 , wherein the first and the second end points p 1  and p 2  are separated by a predetermined distance, and the second and the third end points p 2  and p 3  are separated by the same predetermined distance. Moreover, the inner edge  4614  of the sealant node  461  includes a fourth end point p 4 , a fifth end point p 5 , and a sixth end point p 6 , wherein the fourth and the fifth end points p 4  and p 5  are separated by the predetermined distance, and the fifth and the sixth end points p 5  and p 6  are separated by the predetermined distance. In the embodiment, an area enclosed by the first end point p 1 , the second end point p 2 , and the third end point p 3  is greater than an area enclosed by the fourth point p 4 , the fifth point p 5 , and the sixth point p 6 . In more detail, an area enclosed by connection lines between an arbitrary two of the first point p 1 , the second point p 2 , and the third point p 3 , is greater than an area enclosed by connection lines between an arbitrary two of the fourth point p 4 , the fifth point p 5 , and the sixth point p 6 . 
     In some embodiments, the inner edge  4614  of the node  461  is closer to the third curved path ct 3  than the neighboring connection portion  463 . Namely, the distance between the inner edge  4614  of the node  461  and the third curved path ct 3  is smaller than the distance between the connection portion  463  and the third curved path ct 3 . 
     In the embodiment shown in  FIG. 8 , due to the feature that the inner edge  4614  of the curved segment  46  is closer to the third curved path ct 3  than the outer edge  4612 , the over-flow of the sealant  46  in the display area AA will not occur. As a result, the adverse effect on the display panel  1  resulting from the sealant is avoided. 
       FIG. 9  shows an image of a display panel if observed with an optical microscope, in accordance with some embodiments. The display panel if includes a first substrate  10   f  and a sealant  40   f  A curved segment  42   f  of the sealant  40   f  is located between a straight segment  41   f  and a straight segment  43   f.    
     A method for determining nodes along a curved path ct 6  of the sealant  40   f  is described below. But the method is not limited thereto. 
     Firstly, create a connection line L 1  by connecting any two width centers  411   f  and  412   f  of the straight segment  41   f . Afterwards, create a connection line L 2  by connecting any two width centers  431   f  and  432   f  of the straight segment  43   f . Afterwards, find a point I 1  at the intersection of the connection line L 1  and the connection line L 2 . Note that the width center of the straight segment is positioned at a half of the width of the straight segment. 
     Afterwards, find a sealant node  421   f  at the curved segment  42   f . The sealant node  421   f  is a structure positioned immediately adjacent to the straight segment  41   f  along the application direction of the sealant  40  and has a width arranged in a narrow-wide-narrow manner. Afterwards, create a connection line L 3  passing through an outer convex point p 7  and perpendicular to the connection line L 1 , wherein the outer convex point p 7  of the sealant node  421   f  is a point at the outer edge of the sealant node  421   f  which is farthest from connection line L 1 . Afterwards, find a node nf 1  at the intersection of the connection line L 3  and the connection line L 1 . The node nf 1  is one of the nodes along the curved path ct 6  and corresponds to the center of the sealant node  421   f . Afterwards, make a circle with a center at the point I 1  and with a radius which is equal to the distance between the point I 1  and the node nf 1 , and find another node nf 5  at the intersection of the circle and the connection line L 2 . The node nf 5  is one of the nodes along the curved path ct 6  and corresponds to the center of the sealant node  425   f.    
     A method for determining the rotation center c 6  of the curved path ct 6  on which the node nf 1  and the node nf 5  are located is described below. But the method is not limited thereto. Firstly, create a connection line L 4  passing through the node nf 1  and perpendicular to the connection line L 1 . Afterwards, create a connection line L 5  passing through the node nf 5  and perpendicular to the connection line L 2 . Afterwards, find a rotation center c 6  of the curved path ct 6  at the intersection of the connection line L 4  and the connection line L 5 . The distance r 6  between the rotation center c 6  and the node nf 1  is equals to the distance r 6  between the rotation center c 6  and the node nf 5 , and the distance r 6  is defined as the rotation radius of the curved path ct 6 , as well as the rotation radius of the curved segment  42   f    
     A method for determining the distance D 6  between the two neighboring nodes nf 1  and nf 2  is described below. But the method is not limited thereto. Firstly, find a sealant node  422   f  at the curved segment  42   f . The sealant node  422   f  is a structure positioned immediately adjacent to the sealant node  421   f  along the application direction of the sealant  40  and has a width arranged in a narrow-wide-narrow manner. Afterwards, create a connection line L 6  between an outer convex point p 8  of the sealant node  422   f  and the rotation center c 6 . The outer convex point p 8  is located at the intersection of the outer edge of the sealant node  422   f  and a circle with a center at the rotation center c 6 . In other words, the outer convex point p 8  is a point of the outer edge of the sealant node  422   f  which is tangential to the circle. 
     Afterwards, make a circle with a center at the rotation center c 6  and with a radius which is equal to the rotation radius r 6  so as to determine the curved path ct 6 . Afterwards, find a node nf 2  at the intersection of the connection line L 6  and the curved path ct 6 . The node nf 2  is corresponding to the center of the sealant node  422   f . The distance D 6  is equal to the linear distance between the node nf 1  and the node nf 2 . And the distance D 6  is equal to the linear distance between the sealant node  421   f  and the sealant node  422   f  However, the method for determining the node nf 2  should not be limited to the above-mentioned embodiment. In some embodiments, the node nf 2  is a geometrical center of the sealant node  422   f.    
     In the embodiment shown in  FIG. 9 , the distance d between the edge of the substrate  10   f  and an edge of the display area AA is equal to the shortest distance between an edge of the substrate  10   f  and an edge of the display area AA. The edge of the substrate  10   f  is bounded between an intersection of the connection line L 4  and the edge of the substrate  10   f  and another intersection of the connection line L 5  and the edge of the substrate  10   f . But the present disclosure is not limit thereto. 
       FIG. 10  shows an image of a display panel  1   g  observed with an optical microscope, in accordance with some embodiments. The display panel  1   g  includes a first substrate  10   g  and a sealant  40   g . A curved segment  42   g  of the sealant  40   g  is located between a straight segment  41   g  and a straight segment  43   g.    
     A method for determining nodes along the curved path ct 7  of the sealant  40   g  is described below. But the method is not limited thereto. 
     Firstly, create a connection line L 7  by connecting any two width centers  411   g  and  412   g  of the straight segment  41   g . Afterwards, create a connection line L 8  by connecting any two width centers  431   g  and  432   g  of the straight segment  43   g . Afterwards, find a point  12  at the intersection of the connection line L 7  and the connection line L 8 . Note that the width center of the straight segment is positioned at a half of the width of the straight segment. 
     Afterwards, find a sealant node  421   g  at the curved segment  42   g . The sealant node  421   g  is a structure positioned immediately adjacent to the straight segment  41   g  along the application direction of the sealant  40  and has a width arranged in a narrow-wide-narrow manner. Afterwards, create a connection line L 9  passing through an outer convex point p 9  and perpendicular to the connection line L 7 , wherein the outer convex point p 9  of the sealant node  421   g  is a point at the outer edge of the sealant node  421   g  which is farthest from connection line L 7 . Afterwards, find a node ng 1  at the intersection of the connection line L 7  and the connection line L 9 . The node ng 1  is one of the nodes along the curved path ct 7  and corresponds to the center of the sealant node  421   g . Afterwards, make a circle with a center at the point  12  and with a radius which is equal to the distance between the point  12  and the node ng 1 , and find another node ng 4  at the intersection of the circle and the connection line L 2 . The node ng 4  is one of the nodes along the curved path ct 7  and corresponds to the center of the sealant node  424   g.    
     A method for determining the rotation center c 7  of the curved path ct 7  on which the node ng 1  and the node ng 4  are located is described below. But the method is not limited thereto. Firstly, create a connection line L 10  passing through the node ng 1  and perpendicular to the connection line L 7 . Afterwards, create a connection line L 11  passing through the node ng 4  and perpendicular to the connection line L 8 . Afterwards, find a rotation center c 7  of the curved path ct 7  at the intersection of the connection line L 10  and the connection line L 11 . The distance r 7  between the rotation center c 7  and the node ng 1  is equal to the distance r 7  between the rotation center c 7  and the node ng 4 , and the distance r 7  is defined as the rotation radius of the curved path ct 7 , as well as the rotation radius of the curved segment  42   g.    
     A method for determining the distance D 7  between the node ng 1  and the node ng 2  is described below. But the method is not limited thereto. Firstly, find a sealant node  422   g  next to the sealant node  421   g . The sealant node  422   g  is a structure positioned immediately adjacent to the sealant node  421   g  along the application direction of the sealant  40  and has a width arranged in a narrow-wide-narrow manner. Afterwards, create a connection line L 12  between an outer convex point p 10  of the sealant node  422   g  and the rotation center c 7 . The outer convex point p 10  is located at an intersection of the outer edge of the sealant node  422   g  and a circle with a center at the rotation center c 7 . In other words, the outer convex point p 10  is a point of the outer edge of the sealant node  422   f  which is tangential to the circle. 
     Afterwards, make a circle with a center at the rotation center c 7  and with a radius which is equal to the rotation radius r 7  so as to determine the curved path ct 7 . Afterwards, find a node ng 2  at the intersection of the connection line L 12  and the curved path ct 7 . The node ng 2  is corresponding to the center of the sealant node  422   g . The distance D 7  is equal to the linear distance between the node ng 1  and the node ng 2 . And the distance D 7  is equal to the linear distance between the sealant node  421   g  and the sealant node  422   g . However, a method for determining the node center ng 2  should not be limited to the above-mentioned embodiment. In some embodiments, the node ng 2  is a geometrical center of the sealant node  422   g.    
     In the embodiment shown in  FIG. 10 , the distance d between the edge of the substrate  10   g  and an edge of the display area AA is equal to the shortest distance between an edge of the substrate  10   g  and an edge of the display area AA. The edge of the substrate  10   g  is bounded between an intersection of the connection line L 10  and the edge of the substrate  10   g  and another intersection of the connection line L 11  and the edge of the substrate  10   g . But the present disclosure is not limit thereto. 
       FIG. 11  shows a schematic view of a display panel  1   d , in accordance with some embodiments. The display panel  1   d  includes a first substrate  10   d  and a sealant  40   d . In the embodiment, the first substrate  10   d  has an elliptical shape, and the sealant  40   d  is applied on the substrate  10   d  along the edge of the first substrate  10   d.    
     In some embodiments, in the vicinity of two ends of the minor axis of the first substrate  10   d , the sealant  40   d  includes a first curved segment  42   d . The first curved segment  42   d  is applied along the nodes nd 1 , nd 2 , and nd 3  that are arranged on the first curved path ct 4 . The two neighboring nodes nd 1 , nd 2 , and nd 3  are separated from one another by a distance D 4 , and the first curved path ct 4  has a rotation radius r 4  and a rotation center c 4 . 
     In the vicinity of two ends of the major axis of the first substrate  10   d , the sealant  40   d  includes a second curved segment  44   d . The second curved segment  44   d  is applied along the nodes ne 1 , ne 2 , and ne 3  arranged on the second curved path ct 5 . The two neighboring node center ne 1 , ne 2 , and ne 3  is separated from one the other by a distance D 5 , and the second curved path ct 5  has a rotation radius r 5  and a rotation center c 5 . 
     In some embodiments, under a condition that the manufacturing variance for applying the first curved segment  42   d  is the same as that for applying the second curved segment  44   d . The rotation radius r 5  is smaller than the rotation radius r 4 . Therefore, according to the following equation: 
     
       
      
       d∝√{square root over (r)} 
      
     
     The distance D 5  would be smaller than the distance D 4 . Namely, the rotation radius r 4  and the rotation radius r 5  may satisfy the relation of 0&lt;r 5 /r 4 &lt;1, and the distance D 4  and the distance D 5  may satisfy the relation of 0&lt;D 5 /D 4 &lt;1. 
     Though the sealant nodes of the sealant  40   d  are not shown, the distance between two neighboring nodes is equal to the distance between the two neighboring sealant nodes. Similarly, the rotation radius of the curved path is equal to the rotation radius of the curved segment. 
       FIG. 12  shows an image of a display panel  1   h  observed with an optical microscope, in accordance with some embodiments. The display panel  1   h  includes a first substrate  10   h  and a sealant  40   h . The sealant  40   h  is applied along a curved path ct 8  to form a curved segment  42   h.    
     A method for determining the rotation center c 8  of the curved path ct 8  on which the nodes nh 1  and nh 2  are located is described below. But the method is not limited thereto. Firstly, randomly select two points v 1  and v 2  at an inner edge of the sealant node  421   h  and create a central vertical line L 13 . Afterwards, randomly select two points v 3  and v 4  at the inner edge of the sealant node  421   h  and create a central vertical line L 14 . Find a point  13  at an intersection of the central vertical lines L 13  and L 14 . Afterwards, make a circle with a center at the point  13  and make the circle approach the inner edge of the sealant node  421   h . The circumference of the circle and the inner edge of the sealant node  421   h  meet at two farthest points v 5  and v 6 . A radius central vertical line L 15  is obtained by connecting the two points v 5  and v 6 . Afterwards, obtain another radius central vertical line L 16  on another sealant node  422   h  using the same method. An intersection of the two radius central vertical lines L 15  and L 16  is the rotation center c 8 . The distance r 8  between the rotation center c 8  and the curved path ct 8  is defined as the rotation radius of the curved path ct 8 , as well as the rotation radius of the curved segment  42   h.    
     A method for determining the distance D 8  between the node nh 1  and the node nh 2  is described below. Firstly, find a sealant node  422   h  next to the sealant node  421   h . The node nh 1  is located on the radius central vertical line L 15  and located at a half of the width of the sealant node  421   h . The node nh 1  is located on the radius central vertical line L 16  and located at a half of the width of the sealant node  422   h . The distance D 8  is equal to the linear distance between the node nh 1  and the node nh 2 . And the distance D 8  is equal to the linear distance between the sealant node  421   h  and the sealant node  422   h . However, the method for determining the node nh 1  and the node nh 2  should not be limited to the above-mentioned embodiment. In some embodiments, the node nh 1  is a geometrical center of the sealant node  421   h , and the node nh 2  is a geometrical center of the sealant node  422   h.    
     Embodiments for applying a sealant on a substrate are disclosed. By controlling the parameter (the number of nodes, and distance between nodes) for applying the sealant, the manufacturing time for applying the sealant is adjustable. Therefore, the display panel is produced sufficiently, and the throughput of the display panel is improved. In addition, since the manufacturing variance for applying the sealant is controlled within a particular range, the problem of the sealant being applied over the display area of the display panel is prevented. 
     Although the embodiments and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods, and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. In addition, each claim constitutes a separate embodiment, and the combination of various claims and embodiments are within the scope of the disclosure.