Abstract:
A spacer and a liquid crystal display panel using the same are provided. The spacer is located between a first substrate and a second substrate. The spacer includes a bottom portion and a neck portion. The bottom portion is disposed on the first substrate. The neck portion is disposed on the bottom portion. The contact area between the neck portion and the bottom portion is smaller than that between the bottom portion and the first substrate.

Description:
[0001]     This application claims the benefit of Taiwan application Serial No. 93136800, filed Nov. 29, 2004, the subject matter of which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates in general to a spacer of liquid crystal display panel and a manufacturing thereof, and more particularly to a compression resistant spacer of the display panel and a manufacturing method thereof.  
         [0004]     2. Description of the Related Art  
         [0005]     Liquid crystal display (LCD) panel has replaced conventional CRT monitor and become the mainstream display product. The structure of a liquid crystal display panel mainly comprises two glass substrates assembled in pair, allowing liquid crystals to be infused into the space formed between the two glass substrates.  
         [0006]     Currently, one drop filling (ODF) method is often used in the manufacturing process of infusing liquid crystal into the liquid crystal display panel. In the ODF manufacturing process, firstly, the surface of a TFT substrate or a color filter substrate is applied with sealant. Next, under a vacuum environment, the liquid crystal drips onto the surface of the TFT substrate or the color filter substrate, which has been applied with sealant, for the liquid crystal to be evenly distributed over the region enclosed by the sealant. Then, the TFT substrate and the color filter substrate are assembled in pair. After that, a normal barometric pressure is resumed and is used to assemble the TFT substrate and the color filter substrate to form a liquid crystal display panel. The color filter substrate or the TFT substrate has a spacer thereon, wherein the spacer provides a cell gap between the TFT substrate and the color filter substrate following the assembly of the TFT substrate and the color filter substrate, so that the liquid crystal can be distributed between the TFT substrate and the color filter substrate.  
         [0007]     In the method of infusing the liquid crystal, if the amount of the liquid crystal does not go with the height and the design of the spacer, vacuum bubbles would occur. Under a high temperature, visual defects are likely to occur due to an uneven cell gap between two substrates and is caused by the expansion of liquid crystal. Therefore, the design of increasing the flexibility of the spacer is conducive to the cooperation between the amount of the liquid crystal and the cell gap; thereby the above-mentioned problems are resolved.  
         [0008]     For current color filters with photo spacer, the easiest way to get flexibility behavior is reduce the ratio of photo spacer. However, conventional photo spacer design with low ratio has a poor resistance to compression, so the liquid crystal display panel would easily be damaged by a large external force, hence the faulty rate increasing.  
       SUMMARY OF THE INVENTION  
       [0009]     The object of the invention is to provide a spacer which is flexible during the manufacturing process of liquid crystal infusing to facilitate an appropriate association between the amount of liquid crystal and cell gap, furthermore, after TFT substrate and color filter substrate are assembled in pair, the spacer is compression resistant to the pressure applied onto the liquid crystal display panel by an external force, wherein the spacer can be a photo spacer or made of photoresist material.  
         [0010]     According to an object of the invention, a spacer for a liquid crystal module disposed between a first substrate and a second substrate is provided. The spacer comprises a bottom portion and a neck portion. The bottom portion is adapted to be disposed on the first substrate. The neck portion is disposed on the bottom portion. The contact area between the neck portion and the bottom portion is smaller than that between the bottom portion and the first substrate.  
         [0011]     According to another object of the invention, a liquid crystal display panel is provided. The display panel includes a first substrate, a second substrate and a spacer. The spacer comprises a bottom portion and a neck portion. The bottom portion is adapted to be disposed on the first substrate. The neck portion is disposed on the bottom portion. The contact area between the neck portion and the bottom portion is smaller than that between the bottom portion and the first substrate.  
         [0012]     In one embodiment of the invention, the bottom portion is disposed on part of the first substrate. The neck portion is disposed on the top surface of the bottom portion. The spacer includes a photo spacer. The spacer can be formed into a single body. For example, the spacer, having the bottom portion and a neck portion, may be formed on the first substrate or the second substrate by performing a half-tone masking process. The first substrate and the second substrate are respectively a color filter substrate and a thin film transistor substrate. In other embodiment of the invention, the second substrate and the first substrate are respectively a color filter substrate and a thin film transistor substrate.  
         [0013]     Other objects, features, and advantages of the invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The following description is made with reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1A  is a sectional view showing the status prior to the assembly of two substrates of the liquid crystal display panel according to a first embodiment of the invention;  
         [0015]      FIG. 1B  is a sectional view showing the status after the assembly of two substrates of the liquid crystal display panel of  FIG. 1A ;  
         [0016]      FIG. 2  is a sectional view showing the status prior to the assembly of two substrates of the liquid crystal display panel according to a second embodiment of the invention;  
         [0017]      FIG. 3  is a sectional view showing the status prior to the assembly of two substrates of the liquid crystal display panel according to a third embodiment of the invention;  
         [0018]      FIG. 4A  is a sectional view showing the status when a neck portion contacts a bottom portion and a second substrate at the same time;  
         [0019]      FIG. 4B  is a sectional view showing the status when two neck portions contact a second substrate at the same time;  
         [0020]      FIG. 5  is a flowchart of the formation of a spacer;  
         [0021]      FIG. 6  is a flowchart of a manufacturing method of a liquid crystal display; and  
         [0022]      FIG. 7  is an external force response curve of the spacer. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
     First Embodiment  
       [0023]     Referring to  FIG. 1A , a sectional view showing the status prior to the assembly of two substrates of the liquid crystal display panel according to a first embodiment of the invention is sown. In  FIG. 1A , liquid crystal display panel  100 A comprises a first substrate  101   a , a second substrate  102   a  and a spacer  104 . The spacer  104  is disposed between the first substrate  101   a  and the second substrate  102   a , so that a cell gap (unshown) is formed between the first substrate  101   a  and the second substrate  102   a . The spacer  104  comprises a bottom portion  104   a   1  and a neck portion  104   a   2 . The bottom portion  104   a   1  is disposed between the first substrate  101   a  and the second substrate  102   a . The neck portion  104   a   2  is disposed between the bottom portion  104   a   2  and the second substrate  102   a . The contact area between the neck portion  104   a   2  and the bottom portion  104   a   1  is smaller than that between the bottom portion  104   a   1  and the first substrate  101   a.    
         [0024]     In this embodiment of the invention, the bottom portion  104   a   1  is disposed on part of the first substrate  101   a  and has a top surface  106   a . The neck portion  104   a   2  is disposed on part of the top surface  106   a  of the bottom portion and has a top surface  108   a . The top surface  108   a  abuts against part of the second substrate  102   a  when the first substrate  101   a  and the second substrate  102   a  are assembled in pair. The spacer  104  can be a photo spacer, and the bottom portion  104   a   1  and the neck portion  104   a   2  can be formed in one piece. The first substrate  101   a  and the second substrate  102   a  respectively can be a thin film transistor (TFT) substrate and a color filter substrate, or respectively can be the color filter substrate and the TFT substrate.  
         [0025]     Referring to  FIG. 1B , a sectional view showing the status after the assembly of two substrates of the liquid crystal display panel of  FIG. 1A  is shown. When the first substrate  101   a  and the second substrate  102   a  are assembled in pair, the spacer  104  provides a cell gap D between the first substrate  101   a  and the second substrate  102   a . The contact area between the neck portion  104   a   2  and the second substrate  102   a  is smaller than that between the bottom portion  104   a   1  and the first substrate  101   a . The contact area between the neck portion  104   a   2  and the second substrate  102   a  is substantially equal to that between the neck portion  104   a   2  and the bottom portion  104   a   1 .  
         [0026]     In  FIG. 1A , the first substrate  101   a  has a normal  110   a  extending from a surface  103  of the first substrate  101   a  facing the second substrate  102   a . Any cross sectional area of the neck portion  104   a   2  perpendicular to the normal  110   a  is smaller than any cross sectional area of the bottom portion  104   a   1  perpendicular to the normal  110   a . Moreover, the neck portion  104   a   2  is disposed anywhere on the top surface  106   a  of the bottom portion  104   a   2 . In the present embodiment, the neck portion  104   a   2  is disposed at the center of the top surface  106   a  of the bottom portion  104   a   2 .  
         [0027]     When the first substrate  101   a  and the second substrate  102   a  receive a first external force after having been assembled in pair, the cross sectional area of the neck portion  104   a   2  is smaller than that of the bottom portion  104   a   1 , so the neck portion  104   a   2  would receive a larger pressure and have a larger amount of compression than the bottom portion  104   a   1 . Meanwhile, another part of the top surface  106   a  of the bottom portion  104   a   1  does not contact the second substrate  102   a.    
         [0028]     When the first substrate  101   a  and the second substrate  102   a  receive a second external force, which is larger than the first external force, after having been assembled in pair, the amount of compression of the neck portion  104   a   2  continues to increase until the top surface  106   a  of the bottom portion  104   a   1  contacts the second substrate  102   a . Meanwhile, there would have a large increase in total compressed area.  
         [0029]     When the first substrate  101   a  and the second substrate  102   a  receive a third external force, which is larger than the second external force, after having been assembled in pair, the top surface  106   a  of the bottom portion  104   a   1  contacts the second substrate  102   a . After that, the compression rate and the amount of compression of the spacer  104  are far smaller than that in the event when the bottom portion  104   a   1  does not contact the second substrate  102   a . Because of a much larger cross sectional compressed area after the top surface  106   a  of the bottom portion  104   a   1  contacts the second substrate  102   a , the spacer  104  are substantially not compressed significantly.  
         [0030]     Any skilled in the art will know the invention is not limited in the above-mentioned description. For example, the bottom portion  104   a   1  and the neck portion  104   a   2  include respectively different materials. In one embodiment, the hardness of the neck portion  104   a   2  is larger than the hardness of the bottom portion  104   a   1 . In other embodiment, the hardness of the neck portion  104   a   2  is smaller than the hardness of the bottom portion  104   a   1 .  
       Second Embodiment  
       [0031]     Referring to  FIG. 2 , a sectional view showing the status prior to the assembly of two substrates of the liquid crystal display panel according to a second embodiment of the invention is shown. In  FIG. 2 , liquid crystal display panel  200 A comprises a first substrate  201 , a second substrate  202  and a spacer  204 . The spacer  204  comprises a bottom portion  204   a  and a neck portion  204   b . The bottom portion  204   a  is disposed on part of the first substrate  201  and has a top surface  206 . The bottom portion  204   a  can be a photo spacer. The neck portion  204   b  can be any protrusion area in the second substrate  202 . Second substrate  202  may be a thin film transistor substrate or a color filter substrate. The neck portion  204   b  is disposed on part of the second substrate  202  and has a bottom surface  208 . Part of the bottom surface  208  of the neck portion  204   b  abuts against part of the top surface  206  of the bottom portion  204   a  when the first substrate  201  and the second substrate  202  are assembled in pair. The spacer  204  can be formed into a single body. For example, the spacer  204 , having the bottom portion  204   a  and a neck portion  204   b , may be formed on the first substrate  201  or the second substrate  202  by performing a half-tone masking process.  
         [0032]     When the first substrate  201  and the second substrate  202  are assembled in pair, the spacer  204  provides a cell gap (unshown) between the first substrate  201  and the second substrate  202 .  
         [0033]     The first substrate  201  has a normal  210  extending from the surface  203  of the first substrate  201  facing the second substrate  202 . Any cross sectional area of the neck portion  204   b  perpendicular to the normal  210  is smaller than any cross sectional area of the bottom portion  204   a  perpendicular to the normal  210 .  
         [0034]     When the first substrate  201  and the second substrate  202  receive a first external force after having been assembled in pair, part of the top surface  206  that contacts the bottom surface  208  is compressed, while the rest part of the top surface  206  that does not contact the bottom surface  208  is almost not compressed and does not contact the surface of the second substrate  202 .  
         [0035]     When the first substrate  201  and the second substrate  202  receive a second external force, which is larger than the first external force, after having been assembled in pair, part of the top surface  206  that contacts the bottom surface  208  can be compressed until the rest part of the top surface  206  just contacts the surface of the second substrate  202 .  
         [0036]     When the first substrate  201  and the second substrate  202  receive a third external force, which is larger than the second external force, after having been assembled in pair, the rest part of the top surface  206  contacts the surface of the second substrate  202 . Meanwhile, the compressed area of the spacer  204  increases largely, the bottom portion  204   a  and the neck portion  204   b  are almost not being compressed. In the second embodiment, since the cross sectional area of the bottom portion  204   a  is larger than that of the neck portion  204   b , the deformation of the spacer  204  is mainly due to the neck portion  204   b  and partly due to the bottom portion  204   a . Alternatively, the bottom portion  204   a  and the neck portion  204   b  can be made of different materials. For example, the hardness of the neck portion  204   b  is larger than that of the bottom portion  204   a , i.e., the neck portion  204   b  is almost not compressed, and the compression or deformation is mainly received by or caused by the contact area of bottom portion  204   a . For example, the bottom portion of spacer  204   a  can be a photo spacer. If second substrate  202  is thin film transistor substrate, the neck portion  240   b  can be any protrusion area in thin film transistor substrate as metal line . . . etc. If second substrate  202  is color filter, the neck portion  240   b  can be any protrusion area in color filter substrate. In other embodiment, the hardness of the neck portion  204   b  is smaller than that of the bottom portion  204   a.    
       Third Embodiment  
       [0037]     Referring to  FIG. 3 , a sectional view showing the status prior to the assembly of two substrates of the liquid crystal display panel according to a third embodiment of the invention is shown. The spacer  304  is disposed between the first substrate  301  and the second substrate  302 . Unlike the first embodiment, the third embodiment further comprises an auxiliary portion  304   c  disposed on the neck portion  304   b  in addition to the bottom portion  304   a  and the neck portion  304   b . The bottom portion  304   a , the neck portion  304   b  and the auxiliary portion  304   c  respectively have a top surface  306 , a top surface  308  and a top surface  312 . The spacer  304  can be a photo spacer. The bottom portion  304   a , the neck portion  304   b  and the auxiliary portion  304   c  can be formed in one piece. The cross sectional area of the neck portion  304   b  is smaller than that of the bottom portion  304   a . The cross sectional area of the auxiliary portion  304   c  can either be larger or smaller than that of the neck portion  304   b . When an external force is applied onto the spacer  304 , the bottom portion  304   a , the neck portion  304   b  and the auxiliary portion  304   c  are respectively deformed to resist the external force. The bottom portion  304   a , the neck portion  304   b  and the auxiliary portion  304   c  can have different hardness. For example, the hardness of the bottom portion  304   a  can be larger than that of the neck portion  304   b  and that of the auxiliary portion  304   c , or the hardness of the bottom portion  304   a  can be smaller than the hardness of the neck portion  304   b  and that of the auxiliary portion  304   c , or other arrangements.  
       Fourth Embodiment  
       [0038]     Referring to  FIG. 4A  and  FIG. 4B , the spacer  404   a  can be a photo spacer, which further comprises a neck portion  404   c , a neck portion  404   b . The behavior of spacer under external loading is similar as second embodiment except multi-neck portion.  
       Fifth Embodiment  
       [0039]     Referring to  FIG. 5 , a manufacturing flowchart of a spacer is shown. Firstly, the method begins at step  501 : a bottom portion  104   a   1  is formed on a first substrate  101   a . Lastly, proceed to step  503 : a neck portion  104   a   2  is formed on a bottom portion  104   a   1 . The contact area between the neck portion  104   a   2  and the bottom portion  104   a   1  is smaller than that between the bottom portion  104   a   1  and the first substrate  101   a.    
       Sixth Embodiment  
       [0040]     Referring to  FIG. 6 , a manufacturing flowchart of a liquid crystal display panel is shown. Firstly, the method begins at step  601 : a bottom portion  204   a  is formed on a first substrate  201 . Next, proceed to step  603 : a neck portion  204   a  is formed on a second substrate  202 . Lastly, proceed to step  605 : the first substrate  201  and the second substrate  202  are assembled in pair. The contact area between the neck portion  204   b  and the bottom portion  204   a  is smaller than that between the bottom portion  204   a  and the first substrate  201 .  
         [0041]     Referring to  FIG. 7 , a relative curve between the external force applied on the spacer and the deformation of the spacer is shown. In the relative curve, the y-axis represents external force applied on the spacer, and the x-axis represents the deformation of the spacer. A 1  represents a first force applied on the spacer, A 2  represents a second force applied on the spacer, and A 3  represents a third force applied on the spacer. It can be known from the drawings that the third force A 3  is larger than the second force A 2 , and that the second force A 2  is larger than the first force A 1 . Before the second force A 2  is applied onto the spacer, the spacer has a linear deformation. When the force applied on the spacer equals A 2 , most area of the spacer contacts the opposite substrate. Because the area of the spacer receiving the stress when the stress exceeds the second force A 2  is far larger than the area of the spacer receiving the stress when the force is smaller than A 2 , so that the increase in deformation is reduced sharply and a non-linear deformation curve id formed. When the structure of the spacer disclosed in the second embodiment, the third embodiment and the fourth embodiment receives the first force A 1 , part of the portion is compressed and forms a linear deformation. When the received force is smaller than the second force A 2 , the area of the spacer resisting the force does not change, resulting in a linear compression deformation. Since the area of part of the bottom portion that does not contact the neck portion is far larger than the area of the other part of the bottom portion that contacts the neck portion, in the event of having an force larger than the second force A 2  and having a large increase in loading area of the spacer, there would not be any significant increase in deformation because the bottom portion has contacted the opposite substrate.  
         [0042]     In a linear deformation range with sharp slope, the spacer is flexible, thereby avoiding the bubble on the liquid crystal display panel during the manufacturing process of liquid crystal infusing. The bubble is caused by vacuum void, and flexible spacer can change the internal volume of panel to match the volume of liquid crystal and avoid the vacuum void during the assembly process. Besides, after the TFT substrate and the color filter substrate are assembled in pair, when external pressure becomes larger and the deformation of the spacer exceeds the height of the neck portion, the cross section of the area that the bottom portion contacts the opposite substrate would be increased largely to resist the external force, stop the growth of deformation, and control the deformation of the spacer within a certain range, lest the spacer might over respond and generate plastic deformation, which would cause muras due to changes in the cell gap. The spacer disclosed in the above embodiments maintains the quality of liquid crystal display panel when receiving a large pressure and thus deformed.  
         [0043]     While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.