JP4355174B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a process for producing a liquid crystal display equipment. More specifically, the present invention relates to a technique for improving a spacer used for controlling a substrate gap (gap) of a liquid crystal panel assembled by joining a pair of electrode substrates.
[0002]
[Prior art]
In a conventional liquid crystal display device, a pair of substrates each having at least an electrode, a sealant that joins the pair of substrates together to form a gap (gap) therebetween, and the gap is filled and sealed It is a flat panel having a liquid crystal and a spacer that is interposed between both substrates and restricts the gap to a certain size. As spacers, fine particles have been conventionally used, and are dispersed on the surface of one of the substrates. Recently, photo spacers are used in place of granular scattering spacers. The photo spacer is made of a photosensitive resin material such as a photoresist, and after applying the resin material to one of the pair of substrates with a predetermined thickness, photo etching using photo sensitivity (photo etching) is applied. It is formed.
[Patent Document 1]
JP 2002-268070 A [Patent Document 2]
JP 2002-372717 A [Patent Document 3]
Japanese Patent Laid-Open No. 2001-188235
[Problems to be solved by the invention]
A conventional photospacer is interposed between both substrates bonded to each other, and has a function of keeping the gap constant. The photo spacer is formed in advance on one of the substrates, and comes into contact with the other substrate when assembling the panel to regulate the gap gap. However, the photo spacer is merely fixed to the other substrate surface and is not necessarily firmly fixed by adhesion or the like. Therefore, when a stress is applied to the panel by an external pressure after the panel is formed, a distortion is generated inside the panel, resulting in a deterioration in display quality such as generation of a liquid crystal domain. In addition, the gap between the pair of substrates may be locally increased by external pressure, and vacuum bubbles may be generated. As a result, the display quality may be degraded.
[0004]
[Means for Solving the Problems]
The method of manufacturing a liquid crystal display device according to the present invention is a large-sized substrate for taking out a plurality of panels, and one of a pair of substrates divided into a plurality of panels according to the size of the panel. A step of spraying granular spacers on a peripheral portion that does not constitute the panel; a step of forming a photo spacer made of a resin material on a portion of the pair of substrates constituting the panel of the other substrate; A step of applying a sealant along at least one of the pair of substrates along each of the sections; and the pair of substrates are overlapped, and the adhesiveness of the resin material is drawn out by a heat and pressure treatment to remove the pair of substrates from the pair of substrates. And a step of adhering with a photospacer and the sealing agent.
[0005]
In the method for manufacturing a liquid crystal display device according to the present invention, the granular spacers are dispersed on the periphery of the one substrate by an inkjet method.
[0006]
According to the present invention, the photo spacer is provided with adhesiveness, and the two substrates are bonded to each other to fix the gap constant. Thereby, even if an external pressure is applied to the panel, the gap dimension does not change, and the display quality can be maintained as it is.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a process diagram showing a method of manufacturing a liquid crystal display device according to the present invention. First, as shown in (A), a TFT substrate 1 is prepared. The TFT substrate 1 is integrally formed with a pixel electrode, a thin film transistor (TFT) for driving the pixel electrode, and a peripheral drive circuit. In this embodiment, since a plurality of panels are finally taken out from the large TFT substrate 1, the TFT substrate 1 is divided into sections 2 according to the panel size. The TFT substrate 1 is further subjected to alignment treatment after forming TFTs and pixel electrodes in advance in the semiconductor process. This alignment process is performed, for example, by forming an alignment film such as polyimide and then performing a rubbing process. In addition, alignment marks 5 are formed in advance at two opposite corners of the TFT substrate 1. A conductive common agent 4 is applied to such a TFT substrate 1 using a dispenser 3. The common agent 4 is applied in advance in order to establish conduction with the counter electrode formed on another substrate.
[0008]
Subsequently, as shown in (B), granular spacers 6 are dispersed around the periphery of the TFT substrate 1. Hereinafter, in the present specification, the dispersed granular spacer is referred to as a dispersed spacer, and is distinguished from a photo spacer described later. It is difficult to form a photo spacer at the peripheral portion of the substrate 1 due to unevenness of film thickness and edge rinse. Therefore, instead of the photo spacer, the scattering spacer 6 is arranged on the periphery of the TFT substrate 1. If the scattering spacer 6 is not provided, when the TFT substrate 1 and another substrate are bonded together in a subsequent hot press process, the air cannot be sufficiently removed from the periphery of the substrate, and the uniformity of the panel gap cannot be obtained. As a spraying method of the granular spacer 6, normal dry spraying or wet spraying can be adopted. In dry spraying, spacer material is passed through a tube and sprinkled using static electricity. In addition, wet spraying is a method in which a spacer material is mixed with a solvent and sprinkled. However, it is preferable to selectively spray the granular spacers 6 only on the peripheral portion of the TFT substrate 1 by an ink jet method, rather than a normal dry spraying method or wet spraying method. The ink jet method can selectively supply the granular spacer 6 only to the peripheral portion of the TFT substrate 1.
[0009]
Subsequently, as shown in (C), a large CF substrate 7 is prepared as another substrate to be bonded to the TFT substrate 1. The CF substrate 7 is formed with at least a color filter (CF) and a counter electrode, and is divided for each panel in a section 12 like the TFT substrate 1. The surface of the CF substrate 7 is also subjected to an orientation process in advance. In addition, alignment marks 15 are also formed at two opposite corners of the CF substrate 7. In addition, a photo spacer 16 is formed inside each section 12 of the CF substrate 7. This photo spacer is made of a photosensitive and adhesive (thermosetting) resin material, and for example, an acrylic resin is suitable. This acrylic resin material is formed on the surface of the CF substrate 7 by applying a predetermined thickness and then applying photo etching using photosensitivity. The coating thickness of the resin material is set so as to match the target substrate gap dimension. For example, a negative type photoresist can be used as a resin material having photosensitivity and adhesiveness. After this photoresist is applied with a predetermined thickness, the irradiated portion is cured by selectively irradiating ultraviolet rays through a mask. By performing the development and fixing process in this state, the photo spacers 16 that are discretely arranged in a shell shape on the surface of the CF substrate 7 can be provided. In this embodiment, the photo spacer 16 is formed on the CF substrate 7 side, but it can be formed on the TFT substrate 1 side instead. It is also conceivable to use a normal granular spacer instead of the photo spacer 16. However, granular spacers are less accurate than photo spacers. As a result, when a granular spacer is used, a good result for gap uniformity cannot be obtained due to the influence of variation in particle diameter. Therefore, in the present embodiment, a photo spacer 16 with high accuracy is formed in the part constituting the panel, and the scattering spacer 6 is arranged in the peripheral part of the substrate which does not constitute the panel and the photo spacer cannot be formed. In this way, a panel having excellent gap accuracy can be finally produced by using two types of spacers in a divided manner.
[0010]
In the step (C), the sealant 8 is applied along each section 12 using the dispenser 9 on the CF substrate 7 on which the photo spacers 16 and the alignment marks 15 are formed in advance as described above.
[0011]
The method for manufacturing the liquid crystal display device according to the present invention will be described with reference to the process diagram of FIG. As shown in (D), the CF substrate 7 on which the photo spacers 16 are formed in advance and the TFT substrate 1 on which the scattering spacers 6 are arranged in advance are overlapped with each other. At that time, an ultraviolet curable temporary fixing agent 10 is applied to the peripheral portion of the TFT substrate 1 in advance. The alignment mark 15 formed on the CF substrate 7 side and the alignment mark 5 formed on the TFT substrate 1 side are aligned with each other, thereby positioning the two. Specifically, using the alignment stage, the CF substrate 7 and the TFT substrate 1 are aligned with each other by adjusting the X axis, the Y axis, and the rotation angle θ. At this time, the alignment marks 5 and 15 may be recognized using a camera, the stage may be automatically driven by image processing, and the CF substrate 7 and the TFT substrate 1 may be aligned. After both positioning is completed, the temporary fixing agent 10 is cured by irradiating with ultraviolet rays.
[0012]
Finally, as shown in (E), the temporarily fixed TFT substrate 1 and CF substrate 7 are pressed with a press to create a preset substrate gap. This set gap is determined by the electro-optical characteristics of the liquid crystal material and is usually between 1 and 10 μm. After gap formation with a press, it is put into an oven and baked. Thereby, the sealing agent 8 is cured, and the CF substrate 7 and the TFT substrate 1 are bonded to each other. At this time, since the photo spacer 16 is also subjected to heat treatment by baking, the adhesiveness of the resin material is pulled out, and the CF substrate 7 and the TFT substrate 1 are bonded to each other. As a result, the gap dimension is fixed. Thus, the main steps of the method for manufacturing the liquid crystal display device according to the present invention are completed. In addition, it is good also as a hot press process performed simultaneously, combining the pressurization process by a press and the heating process by oven.
[0013]
FIG. 3 is a flowchart outlining the overall configuration of the liquid crystal display manufacturing method according to the present invention. First, in step S1, a TFT substrate is formed by a semiconductor process. Further, the TFT substrate is subjected to alignment treatment. Subsequently, the common agent is applied in step S2. In step S3, granular spacers are dispersed around the large TFT substrate. On the other hand, a CF substrate is created in step S4. This CF substrate is provided with a color filter and a counter electrode. In addition, a photo spacer is also formed by a photo etching process. Further, the alignment process is performed in the same manner as the TFT substrate. In step S5, a sealant is applied to each section of the CF substrate with a dispenser. In step S6, the TFT substrate and the CF substrate are aligned with each other. In step S7, pressing is performed to obtain a gap dimension between the two substrates. Further, baking is performed in step S8, and the TFT substrate and the CF substrate are bonded to each other. At this time, since the photo spacer having adhesiveness also bonds the two substrates to each other, the gap can be physically fixed. After that, in step S9, the TFT substrate and the CF substrate bonded to each other are cut for each section to form individual panels. Finally, in step S10, liquid crystal is injected and sealed in the internal space surrounded by the sealant of each panel. A flat liquid crystal panel is thus completed. The liquid crystal is vacuum-injected into the gap held constant by the photo spacer, and it becomes possible to exhibit desired electro-optical characteristics.
[0014]
FIG. 4 is a schematic partial cross-sectional view showing a cross-sectional structure of a CF substrate and a TFT substrate bonded to each other. As shown in the figure, the CF substrate 7 and the TFT substrate 1 are bonded to each other by a sealant 8. A photo spacer 16 is also interposed between the two substrates 7 and 1 to maintain a constant gap. In this embodiment, the photo spacer 16 is formed in advance on the CF substrate 7 side, and is adhered to the TFT substrate 1 side by a pressure heating process. However, the present invention is not limited to this, and the photo spacer 16 may be formed on the TFT substrate 1 side and bonded to the CF substrate 7 side by pressure and heat treatment. The photo spacer 16 is formed by applying a resin material having photosensitivity and thermosetting to the CF substrate 7. The photosensitive portion is cured by applying an exposure process through a mask after coating the resin material. When the development and fixing process is performed in this state, the unexposed and uncured portion is removed, and only the cured portion remains in the shape of a shell and becomes the photo spacer 16. On the other hand, scattering spacers 6 are interposed in the periphery of the substrates 7 and 1. In the present invention, instead of this, the scattering spacer 6 is disposed on the peripheral portion where the photo spacer 16 cannot be formed. By providing the scattering spacer 6, the gap between the CF substrate 7 and the TFT substrate 1 is maintained, and the flow of air generated during the process can be smoothed.
[0015]
A color filter 25 colored in advance for each of red, green and blue is formed on the CF substrate 7 side. Also, a black black mask 26 is formed so as to partition each pixel region colored red, green, and blue. A counter electrode 27 is formed on the color filter 25 and the black mask 26 via a protective film. The photo spacer 16 described above is formed on the counter electrode 27 using photo etching. An alignment film 28 is further formed on the counter electrode 27. On the other hand, TFTs and pixel electrodes 20 are formed in an integrated manner on the TFT substrate 1 side. The pixel electrode 20 is covered with an alignment film 21.
[0016]
FIG. 5 is an enlarged photo of a microscope showing one embodiment of the liquid crystal display device manufactured according to the present invention. As shown in the figure, the liquid crystal display device includes a set of fine pixels partitioned by a black mask 26. Each pixel includes a pixel electrode 20. The pixel electrode 20 is divided into a transparent portion 201 and a reflective portion 202. The reflection part 202 has fine irregularities. The liquid crystal display device of this embodiment has a hybrid configuration in which a reflection type and a transmission type are combined. In an environment where there is abundant external light such as in the daytime, an image is projected using the light reflected by the reflection unit 202. In an environment with poor external light such as at night, an image is projected by passing light from a backlight placed on the back of the panel through the transparent portion 201. Such a liquid crystal panel having a hybrid configuration combining a reflective type and a transmissive type can be used, for example, in a PDA display. Here, the photo spacer 16 has a cylindrical shape, and is formed by photolithography at a density of one per three pixels. However, the present invention is not limited to this, and there is no problem as long as the density can keep the gap between the pair of substrates constant.
[0017]
【The invention's effect】
As described above, according to the present invention, after forming the gap between the upper and lower substrates, the upper and lower substrates are fixed and the gap size is kept constant by using the adhesive force of the photo spacer disposed inside the panel. As a result, since the gap of the panel does not change even when an external pressure is applied, the display quality can be kept constant, and the present invention can be used for a liquid crystal display device.
[Brief description of the drawings]
FIG. 1 is a manufacturing process diagram of a liquid crystal display device according to the present invention.
FIG. 2 is a manufacturing process diagram of a liquid crystal display device according to the present invention.
FIG. 3 is a flowchart showing a method for manufacturing a liquid crystal display device according to the present invention.
FIG. 4 is a schematic partial cross-sectional view showing an intermediate state of the liquid crystal display device according to the present invention.
FIG. 5 is an enlarged micrograph of a liquid crystal display device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... TFT substrate, 2 ... Compartment, 5 ... Alignment mark, 6 ... Scatter spacer, 7 ... CF substrate, 8 ... Sealing agent, 12 ... Compartment, 15 ... Alignment mark, 16 ... photo spacer, 20 ... pixel electrode, 26 ... black mask

Claims (2)

A large-sized substrate for taking out a plurality of panels, each of a pair of substrates divided into a plurality of sizes according to the size of the panel. A process of spraying,
Forming a photo spacer made of a resin material on a portion of the pair of substrates that constitutes the panel of the other substrate;
Applying a sealant along each of the sections to at least one of the pair of substrates;
Superimposing the pair of substrates and drawing out the adhesiveness of the resin material by heat and pressure treatment to bond the pair of substrates to the photo spacer with the sealant;
A method of manufacturing a liquid crystal display device having The granular spacers are sprayed on the periphery of the one substrate by an ink jet method.
A method for manufacturing a liquid crystal display device according to claim 1 .

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