CN101221323B - Method for forming multiple alignment films on substrate and pixel structure of liquid crystal display - Google Patents

Abstract

A method for forming multiple alignment films on a substrate and a pixel structure of a liquid crystal display are provided, wherein the pixel structure comprises a plurality of pixel units arranged in an array, and the pixel units comprise a first substrate, a second substrate, two first alignment films and two second alignment films. The second substrate is opposite to the first substrate, the two first alignment films and the two second alignment films are respectively arranged on the first substrate and the second substrate, and each first alignment film is substantially opposite to one of the two second alignment films. The method for forming the alignment films comprises the following steps: forming a groove on the substrate to separate each pixel region and to separate each pixel region into a first sub-pixel region and a second sub-pixel region. Then, a first alignment film is formed on the substrate of the first sub-pixel region, and finally a second alignment film is formed on the substrate of the second sub-pixel region.

Description

Method for forming multiple alignment films on one substrate and pixel structure of liquid crystal display

【Technical field】

The present invention relates to a pixel structure and its forming method used in liquid crystal displays; especially the pixel structure with multiple different alignment films and its forming method.

【Background technique】

Currently common liquid crystal displays use an external voltage to change the arrangement direction of liquid crystal molecules, thereby causing changes in the optical characteristics of the liquid crystal components. Taking Twisted Nematic (TN) liquid crystal display as an example, its basic structure includes two upper and lower conductive glass substrates, nematic liquid crystal injected between the substrates, and two polarizers on the outside of the upper and lower substrates. And a layer of alignment film coated on the conductive glass substrate with friction to form very fine grooves. Because liquid crystal molecules have the flow characteristics of liquid, they are easy to arrange along the direction of the groove, and because the alignment film grooves on the upper and lower conductive glass substrates deviate by 90 degrees, when the liquid crystal is filled in the direction of the grooves of the upper and lower substrates, The liquid crystal molecules will be arranged along the direction of the upper and lower substrate grooves. The binding force of the liquid crystal molecules in the middle part is relatively small, and the binding force of the liquid crystal molecules close to the substrate groove is relatively large. On the whole, the liquid crystal molecules will be twisted. 90 degree arrangement.

When no voltage is applied, the light entering the liquid crystal module will advance with the twisted direction of the liquid crystal molecules. Because the upper and lower polarizers and the alignment film are in the same direction, the light can pass through to form a bright state; on the contrary, if the voltage is applied, the liquid crystal The molecules are arranged towards the applied electric field and arranged perpendicular to the alignment film, so light cannot pass through the second polarizer, forming a dark state, so this alternating light and dark method can be used for display purposes.

On the other hand, take vertical alignment (Vertical Alignment, referred to as VA) liquid crystal display as an example, which uses protrusions (Protrusion) to make the liquid crystal present a pre-tilt angle (Pre-tilt Angle) when it is still; when a voltage is applied to the liquid crystal molecules When it is used, the liquid crystal molecules can quickly fall to different directions, and the light from the back light source can pass through at a faster speed, which greatly shortens the display time. In addition, because the protrusions change the alignment of the liquid crystal molecules, when viewing the liquid crystal display with different viewing angles, the liquid crystal molecules with different alignments can reinforce each other, thereby increasing the viewing angle.

In the existing thin film transistor liquid crystal display, an alignment film material is coated on the glass substrate to provide a certain alignment. In a TN-type liquid crystal display, since the rubbing alignment method can only provide alignment in a single direction, it is easy to have gray scale inversion at a specific viewing angle. In the VA type liquid crystal display, the phenomenon of color wash-out is also prone to occur under the condition of large viewing angle, so that the chroma of the picture watched by the viewer will be greatly reduced under the large viewing angle.

In order to solve the above-mentioned problems, some patents have proposed to carry out a patterning process on the alignment film by means of development and etching, or to modify the surface of the alignment film by means of plasma. However, these methods require additional photoresist coating, exposure, development, etching and other processes, which not only increases the complexity of the manufacturing process, but also increases the processing time and cost. To sum up, how to overcome the alignment problems of different alignment films in the prior art with a simple manufacturing process is a problem to be solved urgently in this field.

【Content of invention】

One object of the present invention is to provide a pixel structure of a thin film transistor liquid crystal display, the pixel structure includes a plurality of pixel units arranged in an array, and each pixel unit includes a first substrate, a second substrate, two first alignment films and 2. A second alignment film. Wherein, the second substrate is arranged opposite to the first substrate. The two first alignment films are respectively arranged on the first substrate and the second substrate, and the two second alignment films are respectively arranged on the first substrate and the second substrate. The first alignment film and the second alignment film are made of different alignment materials, and each first alignment film is substantially opposite to one of the two second alignment films.

Another object of the present invention is to provide a method for forming a plurality of alignment films on a substrate, wherein the substrate includes a plurality of pixel regions arranged in arrays, the method includes: forming a plurality of grooves on the substrate, each of the The pixel area forms a secondary pixel area; forming a first alignment film in one of the secondary pixel areas; and forming a second alignment film in the other sub-pixel area, so that at least part of the two adjacent In the pixel area, the first alignment films are adjacent to each other, and the second alignment films are adjacent to each other.

Another object of the present invention is to provide a method for forming a plurality of alignment films on a substrate, wherein the substrate includes a plurality of pixel regions arranged in arrays, the method includes: forming a plurality of grooves on the substrate, so that each of the The pixel area forms a secondary pixel area; forming a first alignment film in one of the secondary pixel areas; and forming a second alignment film in the other sub-pixel area, so that at least part of the two adjacent In the pixel area, the first alignment film system and the second alignment film system are adjacent to each other.

In the present invention, through special treatment of the glass substrate of the liquid crystal display, different alignment film materials are coated on different areas of the pixel without additional development and etching process, so as to overcome the problem of grayscale inversion in TN mode. And the phenomenon of partial whitening at large viewing angles in VA mode improves the display performance of the liquid crystal display.

In order to make the above-mentioned purpose, technical features, and advantages of the present invention more comprehensible, the following is a detailed description of preferred embodiments in conjunction with the accompanying drawings.

【Description of drawings】

Fig. 1 depicts the implementation manner of applying the present invention to a CF glass substrate of a liquid crystal display in an embodiment;

FIG. 2A, FIG. 2B, FIG. 2C and FIG. 2D show a manufacturing process for forming an alignment film on a substrate;

Fig. 3 depicts the embodiment of applying the present invention to a TFT glass substrate in a liquid crystal display;

4A and 4B respectively show schematic diagrams of pixel units with different alignment film configurations in the pixel structure of the liquid crystal display of the present invention;

5A and 5B respectively show a plurality of pixel units arranged in an array on the substrate of the liquid crystal display of the present invention; and

FIG. 6A , FIG. 6B , FIG. 6C and FIG. 6D respectively show schematic diagrams of different layouts of alignment films on the CF and TFT substrates in the liquid crystal display of the present invention.

【Detailed ways】

The present invention carries out special treatment for glass substrates used in liquid crystal displays, such as applying the present invention to color filter (Color Filter, referred to as CF) glass substrates and thin film transistors (Thin Film Transistor, referred to as TFT) of liquid crystal displays respectively. The purpose of the glass substrate is to coat different alignment film materials in different pixel areas to control the different pretilt angles of the liquid crystal molecules in the pixel areas, which are explained below.

Please refer to FIG. 1, which is a partial schematic diagram of a pixel structure in a TFT liquid crystal display, wherein the pixel structure includes a plurality of pixel units configured in an array (as shown in FIGS. 4A and 4B , multiple pixel units configured in an array). Part of the pixel structure shown in the figure includes a first substrate 100 , a second substrate 200 and a photoresist spacer (Photo Spacer, PS) 300 disposed between the first substrate 100 and the second substrate 200 . Wherein, the second substrate 200 is opposite to the first substrate 100 , and the liquid crystal layer 400 of the liquid crystal display fills the gap between the first substrate 100 and the second substrate 200 . In this embodiment, the first substrate 100 is a CF glass substrate, the second substrate 200 is a TFT glass substrate, and the CF glass substrate 100 includes a number of color components composed of red, green, blue primary colors and/or other colors. The TFT glass substrate 200 includes a plurality of pixel storage capacitors 210 which are spaced apart from each other. It should be noted that other components disposed on the first substrate 100 and the second substrate 200 that are irrelevant to the present invention are omitted and not shown.

The embodiment shown in Fig. 1 relates to the implementation manner of applying the present invention to a CF glass substrate in a liquid crystal display. It should be noted that, as those with ordinary knowledge in this technical field can understand, the present invention can also be applied to On the TFT glass substrate in the liquid crystal display, it is omitted here and not described in detail. In this embodiment, at least one first groove 130 with a width d and a length 1 is disposed on the color resist 110 of the first substrate 100 at intervals. In a specific application, the depth of the groove is substantially 0.5 to 10 microns, and the width is substantially 1 to 50 microns, and the depth and width can be changed according to the position or design of the groove in the pixel. The spaced first grooves 130 can further divide each pixel area of the entire pixel structure into two or more sub-pixel areas, so that each pixel area can be coated with different alignment film materials, so that each The liquid crystal molecules in the pixel area are arranged with different pretilt angles (not shown), so as to achieve the purpose of multi-domain segmentation (Multi-Domain). In addition, it is preferable to arrange the first groove 130 on the opposite side of the pixel storage capacitor 210 on the second substrate 200 on the first substrate 100 to reduce the loss of aperture ratio.

One of the features of the present invention is that the color resist 110 at the two ends of the first groove 130 of the first substrate 100 has a first alignment film 10 and a second alignment film 20 of two different alignment materials respectively, and the two alignment materials are One of a twisted nematic (TN) alignment material, a vertical alignment (VA) alignment material, and an In-Plane Switching (IPS) alignment material is selected. Moreover, the thicknesses of the first alignment film material 10 and the second alignment film material 20 can be the same or different, and the thickness is about 100 to 10,000 angstroms. Since the first alignment film 10 and the second alignment film 20 have different alignment film materials, each pixel region in the liquid crystal display applying the present invention has a different alignment film material.

Please refer to FIG. 2A to FIG. 2D at the same time, which illustrate the manufacturing process of how to form the aforementioned pixel regions with different alignment films on the first substrate or the second substrate. Please refer to FIG. 2A , which shows a plurality of first grooves 130 on the first substrate 100 . Wherein, the method for forming the first groove 130 is to additionally leave one (or more) black lines in the color resist of the pixel in the conventional process steps of making a black matrix (Black Matrix) on the first substrate 100. matrix, so this embodiment does not add an additional process to fabricate the first groove 130 . Then, in the subsequent color-resist etching process, a groove with a width d and a length 1 is etched above the black matrix to form the first groove 130 . Through the first groove 130 , a first pixel region 140 and a second pixel region 150 are formed in a pixel region on the first substrate 100 , so as to achieve the purpose of multi-domain division of the substrate. In a specific application, the depth of the groove is substantially 0.5 to 10 microns, and the width is substantially 1 to 50 microns, and the depth and width can be changed according to the position or design of the groove in the pixel. How to apply the same or different alignment materials on different pixel regions of the pixel structure will be described in detail below.

Next, perform the first alignment film coating, please refer to FIG. 2B , control the size and position of the coating inkjet droplets, so that the first alignment film material 10 is only coated on one side of the first groove 130 . Next, after the first alignment film material 10 is dried, the second alignment film material 20 is coated on the other side of the groove 130 in a similar coating manner, as shown in FIG. 2C . Finally, a single drying process is performed to dry the second alignment film material 20, as shown in FIG. 2D. Wherein, in actual application, the processes shown in FIG. 2B to FIG. 2D can also be changed to coating the two alignment film materials separately, and then uniformly perform a single drying process to simultaneously form the first alignment film 10 and the second alignment film 20 .

Next, please refer to FIG. 3 , the embodiment shown in the figure relates to the implementation of the TFT glass substrate in the liquid crystal display of the present invention. In this embodiment, at least one second groove 230 is disposed on the second substrate 200 at intervals. The spaced second grooves 230 can further divide each pixel area in the entire pixel structure on the TFT glass substrate into two or more sub-pixel areas, so as to facilitate the coating of different alignment film materials on the TFT glass substrate. In each pixel area, the liquid crystal molecules in each pixel area are arranged at different pretilt angles.

In a preferred embodiment, the process for making the second groove 230 is to etch the organic layer of the second substrate 200 with a width It is a groove with a d length of 1 to achieve the purpose of multi-domain segmentation. The organic layer can be a transparent material of Ultra High Aperture (UHA) technology or a color filter on an array (Color filter On Array, referred to as COA) color resistance used in technology. In a specific application, the depth of the groove is substantially 0.5 to 10 microns, and the width is substantially 1 to 50 microns, and the depth and width can be changed according to the position or design of the groove in the pixel.

It should be emphasized that the present invention forms the second groove 230 on the substrate simultaneously when making the through hole of the TFT glass substrate, so this embodiment does not need to add an additional process to make the groove 230 . In addition, similar to the above, it is preferable to arrange the second groove 230 at the position directly above the pixel storage capacitor 210 on the second substrate 200 to reduce the loss of aperture ratio. Since the second groove 230 further divides each pixel area of the pixel structure on the second substrate 200 into two sub-pixel areas, the present invention can apply a method similar to the above to combine the first alignment material 10 and the second alignment film material 20 Coated on both sides of the second groove 230, the thickness is about 100 to 10,000 angstroms, so that each pixel region has a different alignment film material. If the conditions for reducing the loss of aperture ratio are further considered, it is preferable to arrange the second groove 230 directly above the position of the pixel storage capacitor 210 on the TFT glass substrate and use the position of the through hole 220 to avoid occupying the space on the TFT glass substrate. Other positions increase the aperture ratio and the possibility of light leakage.

The above is related to the present invention to divide the pixel area on the TFT glass substrate or the CF glass substrate into two or more sub-pixel areas by setting grooves. The following is a further application based on the foregoing content. For example, different alignment film configurations can be used on the TFT and CF glass substrates of a liquid crystal display to solve different display problems faced by different types of liquid crystal displays.

Please refer to FIG. 4A and FIG. 4B , which are schematic diagrams of pixel units with different alignment film configurations in the pixel structure of a liquid crystal display, wherein the pixel structure includes a plurality of pixel units arranged in an array. Each pixel unit includes a first substrate 100 , a second substrate 200 , a liquid crystal layer 400 , a first alignment film 10 and a second alignment film 20 . Wherein, similar to the foregoing, the first substrate 100 is disposed opposite to the second substrate 200 , and the liquid crystal layer 400 fills the gap between the first substrate 100 and the second substrate 200 . The first alignment film 10 and the second alignment film 20 can be achieved by changing the alignment film material, thickness, surface state, rubbing direction, and the like. Please refer to the drawings below to describe several specific implementation applications of the present invention in detail.

The following descriptions relate to implementations in which both the first and second substrates are subjected to a multi-domain split process. Please refer to FIG. 4A and FIG. 4B, which show that at least one first groove (not shown) is provided on the first substrate 100 in each pixel unit to separate the first alignment film 10 and the first alignment film 100 on the first substrate 100. Two alignment films 20 . Similarly, at least one second groove (not shown) is disposed on the second substrate 200 for separating the first alignment film 10 and the second alignment film 20 on the second substrate 200 . Therefore, in this embodiment, each pixel region on the first substrate 100 and the second substrate 200 has two sub-pixel regions. In the subsequent coating process of the alignment film, the two first alignment films 10 and the two second alignment films 20 can be coated on the secondary pixel regions on the first substrate 100 and the second substrate 200 respectively. In particular, in each pixel region, each of the first alignment films 10 is substantially opposite to one of the two second alignment films 20 .

Specifically, in the embodiment shown in FIG. 4A , each of the first alignment films 10 is substantially opposite to one of the two second alignment films 20 . In the embodiment shown in FIG. 4B , each of the first alignment films 10 is substantially obliquely opposite to one of the two second alignment films 20 . Both of these two implementations generate different electric fields on the left and right sides of each pixel area through the configuration of different alignment films between the first and second substrates, so as to further generate different pre-tilt angle alignments of liquid crystal molecules, and solve the problem of different liquid crystal displays. display issues.

For example, take the implementation shown in FIG. 4A as an example. Since the alignment films on the left and right sides of each pixel area have a first alignment film 10 and a second alignment film 20, the electric field on the left and right sides of each pixel area will generate the same voltage difference. This configuration of the alignment film is especially suitable for TN-type liquid crystal displays, which can effectively increase the pretilt angle of the liquid crystal molecules in the liquid crystal layer to shorten the response time (Response Time). Secondly, taking the implementation shown in FIG. 4B as an example, since the alignment films on the left and right sides of each pixel area use an alignment film as its alignment material, for example, the right side of FIG. 4D is coated with the first alignment film 10 It is distributed on the first and second substrates 100 and 200, and the left side is coated with the second alignment film 20 on the first and second substrates 100 and 200. Therefore, electric fields with different voltage differences are formed on the left and right sides of each pixel area. This configuration of the alignment film is especially suitable for VA-type liquid crystal displays, because the side of the electric field with a large voltage difference in the pixel area can be used to increase the pre-tilt angle of the liquid crystal molecules in the liquid crystal layer and shorten the response time; on the other hand, in addition The side of the electric field with a small voltage difference in the pixel area can be used to avoid excessive pre-tilt angles of the liquid crystal molecules in between, so that the display can maintain a certain light transmittance and solve the problem of VA-type liquid crystal displays with large viewing angles. Defects.

Based on the above, when the multi-domain segmentation technology of the present invention is applied to the CF glass substrate or the TFT glass substrate in the entire liquid crystal display, several possible layout patterns of the alignment film can be formed on the CF glass substrate or the TFT glass substrate. For example, please refer to FIG. 5A and FIG. 5B , which show the adjacent relationship of a plurality of pixel units arranged in an array on a CF glass substrate or a TFT glass substrate in a liquid crystal display. Wherein, each pixel unit 60 on the CF glass substrate or TFT glass substrate is divided into two sub-pixel regions 62 by using the aforementioned bumps, first grooves and/or second grooves and other separators 50, each sub-pixel area 62 The pixel area 62 is coated with the first alignment film 10 or the second alignment film 20 by inkjet.

Taking FIG. 5A as an example, a plurality of equidistant or unequal spacers 50 are formed on the CF or TFT substrate, so that each pixel area forms a secondary pixel area. Next, a first alignment film 10 is formed in one of the secondary pixel regions 62 . Finally, the second alignment film 20 is formed on another sub-pixel area 62, so that at least part of two adjacent pixel areas on the substrate, the first alignment film 10 is adjacent to each other, and the second alignment film 20 is adjacent to each other. That is, on the CF or TFT substrate, the first alignment film adjacent to the sub-pixel area forms a plurality of continuous strips 12 of the first alignment film, and the second alignment film adjacent to the sub-pixel area forms a plurality of continuous strips of the second alignment film 22, and each of the first continuous strips of alignment film 12 and each of the second continuous strips of alignment film 22 are arranged alternately.

Taking FIG. 5B as an example, a plurality of equidistant or unequal spacers 50 are formed on the CF or TFT substrate, so that each pixel area forms a secondary pixel area. Next, a first alignment film 10 is formed in one of the secondary pixel regions 62 . Finally, the second alignment film 20 is formed on another sub-pixel area 62, so that the first alignment film 10 and the second alignment film 20 are adjacent to each other in at least part of two adjacent pixel areas on the substrate. That is, on the CF or TFT substrate, a plurality of continuous strips 12 of the first alignment film and a plurality of continuous strips 22 of the second alignment film are formed in adjacent sub-pixel regions, wherein every two continuous strips 12 of the first alignment film are adjacent to each other Every two continuous strips 22 of the second alignment film are also adjacent to each other, and two adjacent continuous strips 12 of the first alignment film and two adjacent continuous strips 22 of the second alignment film are alternately arranged.

Furthermore, by using the layout shown in FIG. 5A and FIG. 5B in conjunction with the alignment film configuration between the first and second substrates shown in FIG. 4A and FIG. 4B, several changes in specific implementation aspects can be formed, which are described below. .

Please refer to FIG. 6A, which is an embodiment of FIG. 4A combined with FIG. 5A. The first alignment film 10 on one substrate is substantially opposite to the second alignment film 20 on the other substrate, and is arranged on the first substrate. The second alignment films 20 on the 100 are adjacent to each other, and the second alignment films 20 disposed on the second substrate 200 are adjacent to each other. That is, the first and second alignment films 10 and 20 between the two substrates are facing each other, and the continuous strips of the first alignment film 12 and the continuous strips of the second alignment film 22 on each substrate are arranged alternately. .

Please refer to FIG. 6B, which is an embodiment of FIG. 4A with FIG. The alignment films 10 are adjacent to each other, and the first alignment films 10 disposed on the second substrate 200 are adjacent to each other. That is to say, the first and second alignment films 10 and 20 between the two substrates face each other, and the two adjacent continuous strips 12 of the first alignment film and the two adjacent continuous strips 22 of the second alignment film on each substrate are aligned with each other. Alternately.

Please refer to FIG. 6C, which is an embodiment of FIG. 4B with FIG. 5A. The first alignment film 10 on one substrate is substantially obliquely opposite to the second alignment film 20 on the other substrate, and is arranged on the first substrate. The first alignment films 10 on the 100 are adjacent to each other, and the second alignment films 20 on the second substrate 200 are adjacent to each other. That is, the first and second alignment films 10 and 20 between the two substrates are obliquely opposite, and the continuous strips 12 of the first alignment film and the continuous strips 22 of the second alignment film on each substrate are arranged alternately. .

Please refer to FIG. 6D, which is an embodiment of FIG. 4B with FIG. The alignment films 20 are adjacent to each other, and the first alignment films 10 disposed on the second substrate 200 are adjacent to each other. That is, the first and second alignment films 10 and 20 between the two substrates are obliquely opposite to each other, and the two adjacent continuous strips 12 of the first alignment film and the two adjacent continuous strips 22 of the second alignment film on each substrate are connected to each other. Alternately.

To sum up, the present invention uses multi-domain segmentation technology to separate the pixel areas of the glass substrate in the liquid crystal display without additional development and etching processes, so that each pixel area can be coated with different alignment film materials, resulting in The configuration changes of several alignment films affect the pre-tilt alignment of liquid crystal molecules in the liquid crystal layer, thereby improving the display performance of the liquid crystal display.

The above-mentioned embodiments are only used to illustrate the implementation of the present invention and explain the technical features of the present invention, and are not intended to limit the scope of protection of the present invention. Any changes or equivalence arrangements that can be easily accomplished by those skilled in the art fall within the scope of the present invention, and the protection scope of the present invention should be based on the scope of the patent application.

Claims (7)

1. the image element structure of a LCD comprises a plurality of picture elements unit of array configuration, each picture element unit have one for the first time picture element region with one the second time picture element region, respectively this picture element unit comprises:

One first substrate;

One second substrate is oppositely arranged with this first substrate;

2 first alignment films are divided on this first substrate of this of picture element region first time, and for the second time on this second substrate of picture element region; And

2 second alignment films, be divided on this second substrate of this of picture element region first time, and be somebody's turn to do on this first substrate of the picture element region second time, and respectively this second alignment film is with respectively this first alignment film is different, wherein one of them is oblique relative for this first alignment film and this 2 second alignment film, and this first alignment film and this second alignment film have different alignment materials, one of them alignment materials of this first alignment film and this second alignment film, be selected from a stable twisted nematic alignment materials, a vertical orientation type alignment materials, a horizontal rotation type alignment materials one of them; And

One liquid crystal layer is located between this first substrate and this second substrate.

2. image element structure according to claim 1 is characterized in that, this first alignment film and this second alignment film have different thickness.

3. image element structure according to claim 1 is characterized in that, in each two adjacent picture element unit of this array configuration, second alignment film of being located on this first substrate abuts mutually, and first alignment film of being located on this second substrate abuts mutually.

4. image element structure according to claim 1 is characterized in that, in each two adjacent picture element unit of this array configuration, first alignment film of being located on this first substrate abuts mutually, and second alignment film of being located on this second substrate abuts mutually.

5. image element structure according to claim 1 is characterized in that, this first substrate is provided with at least one first groove, in order to first alignment film and second alignment film on this first substrate of interval; This second substrate is provided with at least one second groove, in order to first alignment film and second alignment film on this second substrate of interval.

6. image element structure according to claim 5 is characterized in that, respectively the degree of depth of this at least one first groove and at least one second groove is 0.5 to 10 micron, and width is 1 to 50 micron.

7. image element structure according to claim 5 is characterized in that, this second substrate more comprises at least one picture element storage capacitors, and is relative with this at least one first groove.

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