JP2009092766A - Display device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device whose frame area is reduced by narrowing the width of a region in which a sealing material is disposed and to provide its manufacturing method. <P>SOLUTION: In the display device having a pair of substrates disposed opposite to each other and the sealing material sticking the pair of substrates in an outer side region of a display region, the substrate has an underlayer of the sealing material in a region in contact with the sealing material and a contact angle to the sealing material in the region in contact with the sealing material is smaller than a contact angle to the sealing material in a peripheral region of the region in contact with the sealing material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a display device and a manufacturing method thereof. More specifically, the present invention relates to a display device suitable for a mobile device such as a mobile phone and a method for manufacturing the display device.

In recent years, there has been a demand for further downsizing and weight reduction in portable electronic devices such as mobile phones on which flat panel displays (FPD) such as liquid crystal display devices and organic electroluminescence (EL) display devices are mounted. Yes. Along with this, there is a tendency to reduce the size of the display area, that is, to narrow the frame, and development has been actively conducted.

For example, in a liquid crystal display device widely used in electronic notebooks, cellular phones, etc., a non-display area (frame area) that cannot be used for display is provided between the outer periphery of the display area and the edge of the liquid crystal display panel. Have. The non-display area includes an area in which wiring for displaying pixels, a sticker print area, and the like are included. By narrowing the non-display area, the display area can be increased without increasing the outer size of the panel. It can be widened.

However, in a display device such as a liquid crystal display device, an organic EL display device, or a plasma display, if the frame region is narrowed, the sealing material before curing may ooze out to the outside of the frame region, and the sealing material oozes out to the outside. As a result, the outer peripheral edge of the display device may become defective in manufacturing. In order to prevent such bleeding, it is necessary to provide a margin between the frame area and the seal printing area, and there is room for improvement in that the non-display area becomes large.

Therefore, as one of the methods for reducing the size of the frame region, a method is disclosed in which a wall portion is provided along a part of the sealing material to prevent the sealing material from seeping out and spreading by physical force. (For example, refer to Patent Document 1).

From the viewpoint of disposing the sealing material, there is a problem that ionic impurities eluted from the sealing material and ionic impurities generated by irradiating with ultraviolet rays diffuse into the liquid crystal. In order to suppress this, a method of disposing a polyimide resin film in a region between the display region and the outer seal line has been disclosed (for example, see Patent Documents 2 and 3). Further, in Patent Document 3, the surface energy of the alignment film between the alignment film and the display region is changed from the surface energy of the alignment film in the display region by irradiating the alignment film between the alignment film and the display region with ultraviolet rays. A method of raising is disclosed.

In addition, as a technique for controlling the printing position of the alignment film, a method of providing a highly water-repellent print control pattern for controlling the wetting and spreading of the alignment material between the seal and the display area is disclosed (for example, patents). Reference 4).
JP 2007-10784 A JP-A-10-260406 Japanese Patent Laid-Open No. 10-339883 JP 2007-114586 A

However, in Patent Document 1, a wall portion is provided along the sealing material to prevent the sealing material from leaking out, but a space for providing the wall portion and a margin region for providing the wall portion are required. There was room for improvement because it became a factor that hindered the narrowing of the frame of liquid crystal display panels.

In Patent Document 2, an alignment film having a surface energy higher than the surface energy of the display region is arranged in a region between the display region and the seal line outside the display region. There is a risk of spreading to the area side. In Patent Document 3, an addition type polyimide resin that is partially overlapped with or close to an injection-side seal pattern of a sealing resin including an injection port that encloses liquid crystal outside the edge of the polyimide resin film, in parallel with the seal pattern. Although a film is provided, even in this form, the sealing material may spread wet to the display region side. In Patent Document 4, a region with high water repellency that controls the wetting and spreading of the alignment material is formed between the sealing material and the display region, but a water-repellent region is provided outside the sealing material. There is a possibility that the sealing material spreads outside the panel.

The present invention has been made in view of the above situation, and an object thereof is to provide a display device with a reduced frame area and a method for manufacturing the same.

The inventor has made various studies on reducing the frame area (non-display area) of the display device, and has paid attention to the arrangement area of the seal for bonding a pair of substrates. Then, a base layer of the seal is provided in the area in contact with the seal, and the contact angle with the seal material in the area in contact with the seal (the flow material before the seal is cured) is determined from the contact angle with the seal material in the peripheral area in the area in contact with the seal. It has been found that the sealing material can be prevented from seeping out and the frame area can be reduced in size, and the above problem can be solved brilliantly, and the present invention has been achieved. Is.

That is, the present invention is a display device having a pair of substrates disposed opposite to each other and a seal for bonding the pair of substrates in a region outside the display region, wherein the substrate is a region in contact with the seal In the display device, the contact angle with the seal material in the region in contact with the seal is smaller than the contact angle with the seal material in the peripheral region in the region in contact with the seal.
The present invention is described in detail below.

The display device of the present invention includes a pair of substrates arranged to face each other, and a seal that bonds the pair of substrates in a region outside the display region (outer peripheral region). The pair of substrates has a display area and an outer peripheral area outside the display area and not used for display. A seal for bonding the pair of substrates is disposed in the outer peripheral region. In the present specification, the “display region” is a region where an image can be displayed. For example, in the case of a liquid crystal display device, the image is displayed when the substrate constituting the liquid crystal display device is viewed in plan view. This is an inner region in the substrate plane including a region where a color filter, a pixel electrode, etc. constituting the endmost pixel used in the above are disposed. Further, in the case of an organic EL display device, it is an inner region in a substrate plane including a region where an organic light emitting element constituting the endmost pixel used for displaying an image is arranged. In the case of a plasma display, This is an inner region in the plane of the substrate including the region where the phosphor constituting the endmost pixel used for image display is arranged. Note that the pixel is the smallest unit element constituting the image, and indicates, for example, a single color such as red, green, or blue.

For example, in the case of a liquid crystal display device, the pair of substrates has a shape corresponding to a pixel region on a TFT array substrate in which TFT elements are provided on a glass substrate or the like and a substrate made of non-alkali glass or the like. It is preferable that a colored layer made of a photosensitive material such as red, green, and blue is a CF substrate disposed in the display region. In the case of an organic EL display device, a substrate on which a TFT element and a light-emitting element containing an organic light-emitting material are arranged and a sealing substrate for sealing the inside of the panel are preferable. Furthermore, in the case of a plasma display, it is preferable that the substrate is a substrate on which phosphors constituting the pixels are arranged and a substrate on which address electrodes are arranged.

The substrate has a seal underlayer at least in a region in contact with the seal. The underlayer may be disposed so as to surround the entire display region or may be partially disposed as long as it is disposed in the outer peripheral region outside the display region. From the viewpoint of suppressing the spread, it is preferable to surround the entire display area. For example, when the seal disposed in the outer peripheral region is composed of four sides, it is sufficient that the base layer is provided below at least one side of the four sides constituted by the seal, but the bottom layer is provided below all four sides. It is preferable that a stratum is provided and surrounds the entire display area. In addition, the entire surface on the seal side does not have to be in contact with the seal, but the seal is in contact with the entire base layer. Note that the side surface of the base layer (the surface on the substrate in-plane direction side) need not be in contact with the seal.

In the substrate, the contact angle with the sealing material in the region in contact with the seal is smaller than the contact angle with the sealing material in the peripheral region of the region in contact with the seal. In this specification, the “peripheral region” refers to both the display region side of the region in contact with the seal and the outside of the panel. That is, the contact angle of the substrate in the region in contact with the seal is smaller than the contact angle with respect to the seal material on both the display region side and the outside of the panel in the peripheral region of the region in contact with the seal. According to this, since the base layer has a small contact angle with respect to the seal material on the surface of the region in contact with the seal, the spread of the seal material can be suppressed when the seal material is applied, and the seal can be applied separately. It becomes easy. Further, the pattern forming the seal can be thinned. As a result, the distance from the seal to the outside of the panel and the distance from the seal to the display area can be designed to be short, and the area of the non-display area can be reduced.

In the present specification, “seal” is to bond a pair of substrates and seal the inside of the panel, and “seal material” refers to a fluid material before the seal is cured, and its form Examples thereof include a liquid prepolymer before polymerization and curing, a solution in which a material constituting the seal is dissolved in a solvent, a dispersion in which the material constituting the seal is dispersed, and the like. The “contact angle” to be cured refers to an angle formed by the surface of the sealing layer of the base layer and the surface of the stationary sealing material when the sealing material is disposed on the surface of the base layer on the seal side. The contact angle can be measured using, for example, the θ / 2 method, the tangent method, or the like. In the θ / 2 method, when a droplet placed on a plane is observed from a cross section, the angle formed by the straight line connecting the left and right end points and the apex of the droplet with the plane on which the droplet is placed is doubled. This is a method for obtaining the contact angle. The tangent method is a method in which the contour shape of a droplet is assumed to be a part of a circle, the center of the circle is obtained, and the angle formed by the tangent of the circle and the plane on which the droplet is placed is obtained as the contact angle.
In addition, the hierarchy of the area | region which touches a seal | sticker, and the hierarchy of a periphery area | region may be in the same hierarchy (same plane), may be in a different hierarchy, and is not specifically limited. For example, the level on the display area side of the area in contact with the seal may be higher than the level of the area in contact with the seal, and the level outside the area in contact with the seal may be on the same plane as the level of the area in contact with the seal, The layer outside the region in contact with the seal may be higher than the layer in the region in contact with the seal, and the layer on the display region side of the region in contact with the seal may be on the same plane as the layer in the region in contact with the seal.

The underlayer may be provided only on one of the pair of substrates, or may be provided on both substrates. In the case where it is provided only on one of the pair of substrates, the number of manufacturing steps can be reduced as compared with the case where it is provided on both. Further, in the case of being provided on both of the pair of substrates, since the spread of the sealing material can be suppressed by both the substrates, the non-display area can be further narrowed.

The underlayer may be a part of a member constituting the display device, for example, a part of an alignment film in the case of a liquid crystal display device. The underlayer is not particularly limited as long as it is disposed in the outer peripheral region rather than the display region, and the contact angle of the seal material in the region in contact with the seal is smaller than the peripheral region in the region in contact with the seal.

The underlayer is preferably made of a material having a small contact angle with respect to the sealing material, in other words, a material having high wettability with respect to the sealing material. Moreover, it is preferable that the material which comprises the peripheral region of the area | region which contact | connects a seal | sticker is comprised by the material with a large contact angle with respect to a sealing material, in other words, the wettability with respect to a sealing material is small. According to this, since the spread of the sealing material can be further suppressed, the frame can be narrowed. Furthermore, it is preferable that the underlayer is composed of a member constituting the display device. According to this, an increase in the number of manufacturing steps can be suppressed, and productivity can be improved.

The underlayer is preferably an organic film having a bond with a relatively low bond energy such as a C—C bond or a C—H bond. By cleaving the C—C bond, C—H bond, etc., an oxidation reaction in which the cleaved atom is bonded to oxygen in the air proceeds. As a result, many oxygen atoms having lone electron pairs are present on the surface of the underlayer, and the polarizability of the alignment film is increased. According to this, when the site | part with high polarity, such as an alkyl group and a carbonyl group, is contained in a sealing material, a contact angle can be made small. Examples of the material constituting the base layer include a polyimide resin and a polyamide resin. In addition, the material constituting the underlayer is preferably a material having many alkyl groups that are susceptible to change in the electronic state by ultraviolet irradiation.

The substrate preferably has a contact angle with water in a region in contact with the seal smaller than a contact angle with a seal material in a peripheral region of the region in contact with the seal. That is, it is preferable that the substrate has a lower water repellency in a region in contact with the seal than in a peripheral region of the region in contact with the seal. By measuring the contact angle with water in the region in contact with the seal and in the peripheral region, it can be used as an index of the surface energy in those regions. For example, when the contact angle between water and the surface of the underlayer when water is placed on the underlayer surface is large, the surface of the thin film has a low surface energy, and when the contact angle is small, the surface of the thin film has a high surface energy. It can be said. In addition, since the contact angle of the sealing material varies depending on the surface energy as in the case of water, the contact angle with respect to the sealing material can be used as an index of the sealing material by measuring the contact angle with water. The region in contact with the seal preferably has a contact angle with water of 10 to 30 °, and more preferably 10 to 15 °. Moreover, it is preferable that the peripheral area | region of the area | region which contact | connects a seal | sticker is 90-120 degrees in the contact angle with respect to water. Furthermore, the difference in contact angle with water between the region in contact with the seal and the surrounding region is preferably 60 ° or more, and more preferably the difference in contact angle with water is 75 ° or more.
The contact angle with water in the region in contact with the seal exceeds 30 °, the contact angle with the seal material in the peripheral region of the region in contact with the seal is less than 90 °, or the contact angle between the region in contact with the seal and the peripheral region If the difference is less than 60 °, the sealing material may not be sufficiently prevented from spreading. In addition, the seal is arranged on the entire surface of the base layer on the seal side, and the contact angle with water is 10 to 30 ° or less, so that the seal material is kept on the base layer and the spread of the seal material is sufficiently suppressed. can do. As a result, the area for arranging the seal can be reduced, and the area of the non-display area can be reduced.

The seal and the seal material are preferably composed of a material containing an alkyl group and / or a carbonyl group. Alkyl groups and carbonyl groups are highly polar. Therefore, when the surface of the underlayer has polarity, the contact angle of the sealing material with respect to the underlayer is reduced because it attracts more strongly with the surface of the underlayer. As a result, wetting and spreading of the sealing material can be suppressed, and the frame area can be reduced. Note that the seal is preferably an ultraviolet curable resin that is cured by irradiating the sealing material with ultraviolet rays, or a thermosetting resin that is cured by performing a heat treatment on the sealing material. Further, as the material constituting the seal and the seal material, a material having strong ionicity can be preferably used. For example, an epoxy-based sealing material using an epoxy resin and a highly polar oligomer as a curing material thereof is used. be able to. As the oligomer, polyhydric alcohols, ketones, esters and the like can be used. By using the epoxy-based sealing material as a sealing material, for example, the sealing material can be more effectively retained in a region where the surface energy is increased by ultraviolet irradiation or the like.

A preferred embodiment of the display device of the present invention will be described in detail below.
The display device has a liquid crystal layer sandwiched between a pair of substrates on the display region side of the seal, and has an alignment film in the display region of the substrate, and the base layer is a material constituting the alignment film Preferably, the underlayer is formed of the same material as the alignment film. The alignment film is a film provided for aligning the liquid crystal molecules in the liquid crystal layer, and is generally made of a polymer film such as polyimide or polyamide, and the surface can be easily modified. Therefore, the contact angle can be reduced. In general, in a liquid crystal display device, since an alignment film is provided on a pair of substrates including a color filter substrate and a TFT array substrate, a base layer of a seal can be disposed without increasing the number of manufacturing steps. In the conventional liquid crystal display device, since the base layer is disposed only on the common electrode or the like, it is difficult to change the contact angle with respect to the seal material in the region in contact with the seal.

The underlayer preferably has a modified region in contact with the seal. In the underlayer, the surface of the region in contact with the seal is modified, whereby the surface of the underlayer is activated and the contact angle with respect to the seal material can be further reduced. Moreover, when forming a base layer with the same material as an orientation film, it is preferable to modify | reform with an ultraviolet-ray. The wavelength and intensity of the ultraviolet rays may be in a wavelength range and intensity that can modify the surface of the underlayer, and it is preferable that the C—C bond and the C—H bond can be cut. When the underlayer is an organic film having a C—C bond and a C—H bond, the contact angle of the underlayer surface with the sealing material is reduced by cutting the C—C bond and the C—H bond on the surface of the underlayer. can do. In the region to be modified, the entire region in contact with the seal may be modified, or a part of the region in contact with the seal may be modified. The seal is preferably arranged without protruding from the region where the underlayer is modified.

The underlayer is preferably provided on each of the pair of substrates. According to this, in both of the pair of substrates, the contact angle with respect to the sealing material in the region in contact with the seal is made smaller than the contact angle with respect to the sealing material in the peripheral region in the region in contact with the seal, thereby suppressing the spread of the sealing material. be able to. For example, when a first base layer is disposed on a pair of substrates and a sealing material is disposed on the first base layer, by providing a second base layer on the substrate facing the substrate on which the sealing material is disposed, When a pair of substrates are bonded together, the spread of the sealing material can be suppressed even on the opposing substrate side. Note that the base layer provided on each of the pair of substrates may be made of the same material or may be made of different materials. Moreover, it is preferable that the said base layer is provided in each of a pair of board | substrate, and the said seal | sticker is arrange | positioned on each base layer. A pair of board | substrates are bonded together by making the sealing materials provided on each base layer overlap. When applying the sealing material to both of the pair of substrates, the spread of the sealing material when the pair of substrates is bonded can be suppressed, and one side can be applied rather than applying the sealing material to only one of the substrates. Since the amount of the sealing material applied to the substrate can be small, the spread when applied can be further suppressed.

The present invention is also a method for manufacturing the display device, wherein the manufacturing method includes a step of disposing a base layer of the seal in an outer peripheral region of the substrate, and a step of modifying a region in contact with the seal of the base layer. Also, the display device manufacturing method includes a step of arranging a sealing material on the base layer, a step of bonding a pair of substrates, and a step of solidifying the sealing material in this order.

By manufacturing a display device using the above manufacturing method, a display device with a reduced frame area can be manufactured. Further, since the sealing material does not ooze out to the outside of the panel and the display area, the yield can be improved.

The step of disposing the base layer may be performed in the same step as the step of forming other members constituting the display device, or may be performed in another step, and is not particularly limited, but constitutes the display device. When forming by the same process as another member, the increase in the number of manufacturing processes can be suppressed.

In the step of modifying the region in contact with the seal of the underlayer, the contact angle with respect to the seal material can be further reduced by modifying the surface in contact with the seal of the underlayer. For example, in the case of a base layer formed of polyimide, polyamide or the like, the C—C bond and C—H bond of polyimide irradiated with ultraviolet rays can be cut by irradiating the base layer with ultraviolet rays. . As a result, since an oxidation reaction that combines with oxygen in the air proceeds, there are many oxygen atoms having lone electron pairs on the surface of the underlayer. As a result, when the sealing material has a highly polar part such as an alkyl group or a carbonyl group, the surface of the underlayer attracts the alkyl group and / or the carbonyl group, and the wettability of the surface is improved, and the contact is improved. The corner can be reduced.

The step of solidifying the sealing material is determined by the sealing material. For example, when the sealing material is a thermosetting resin, it can be solidified by heating. When the sealing material is an ultraviolet curable resin, it can be solidified by irradiating with ultraviolet rays.

According to the display device of the present invention, since the contact angle with respect to the sealing material in the region where the substrate and the seal are in contact is smaller than the peripheral region of the region in contact with the seal, the spread of the sealing material due to the bonding of the two substrates is suppressed. be able to. Since the spread of the seal material is suppressed, the distance between the seal and the outside of the panel and the length between the seal and the display area can be designed to be shorter than when no base layer is provided in the seal print area. For this reason, the non-display area existing outside the display area can be narrowed. That is, a narrow frame can be achieved.

Embodiments will be described below, and the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited only to these embodiments. In the present specification, an embodiment of a liquid crystal display device is described. However, the present invention is not limited to a liquid crystal display device, and a display device in which two substrates are bonded to each other in a panel outer peripheral region using a seal. However, the present invention is not particularly limited, and the present invention can be applied to an organic electroluminescence display device, a plasma display, and the like.

(Embodiment 1)
The configuration of the liquid crystal display device according to Embodiment 1 of the present invention will be described below.
FIG. 1 is a schematic cross-sectional view illustrating the configuration of the liquid crystal display device according to the first embodiment. In the liquid crystal display device according to the first embodiment, as shown in FIG. 1, the liquid crystal layer 131 sandwiched between the TFT array substrate 120 and the color filter substrate 110 arranged to face each other is sealed with a seal 130. A liquid crystal display panel is configured. The seal 130 is formed by bonding a seal material applied to the TFT array substrate 120 and a seal material applied to the CF substrate 110, and the bonding surface 131 is formed between the seal materials applied to each substrate. Indicates the boundary. The TFT array substrate 120 is provided with external connection terminals (not shown), and a liquid crystal display driver (not shown) is mounted on the liquid crystal display panel.

(Configuration of CF substrate)
First, the configuration of the CF substrate will be described.
As shown in FIG. 1, a CF substrate 110 has a shape corresponding to a pixel region on a substrate 111 made of alkali-free glass, and a colored layer 113 made of a photosensitive material such as red, green, and blue, etc. Is placed inside. In a region where the colored layer 113 is not disposed, a light-shielding black matrix (BM) 112 made of metal chromium, acrylic photosensitive resin, or the like is disposed so as to surround the colored layer 113. A transparent electrode 114 made of indium tin oxide (ITO) or the like is provided on the coloring layer 113 and the BM 112. Here, the display area refers to the inner area of the liquid crystal display panel including the outermost colored layer and the area where the BM arranged between the colored layer and the colored layer is arranged. The outer peripheral area refers to an area outside the display area of the liquid crystal display panel.

FIG. 2 is a schematic plan view showing the positional relationship between the alignment film of the CF substrate and the seal underlayer 116 according to the first embodiment. As shown in FIGS. 1 and 2, an alignment polymer resin film made of polyimide or the like is provided on the substrate 111 as an alignment film 115 in the display region 150. Further, the oriented polymer resin film is provided as an underlayer 116 of the seal 130 in an outer peripheral region 160 including a region 165 in contact with the seal and a peripheral region 166 in the region in contact with the seal. The alignment film 115 is rubbed with a rubbing roller. Note that the base layer 116 may or may not be rubbed when the alignment film 115 is rubbed, but the base layer is preferably not rubbed. If the underlying layer has molecular orientation by rubbing, the contact angle with the sealing material may be increased. The underlayer 116 includes an upper layer 116b modified by ultraviolet irradiation and a lower layer 116a of the unmodified underlayer.

(Configuration of TFT array substrate)
Next, the configuration of the TFT array substrate will be described.
The TFT array substrate 120 according to the first embodiment is configured by arranging an alignment film 125 and a base layer 126 on an element substrate 121. The element substrate 121 is provided with a TFT element on a substrate made of alkali-free glass or the like. The TFT element is provided at each intersection of a plurality of gate lines and source lines provided so as to extend in parallel to each other in an orthogonal direction. Then, the drain electrode of the TFT element is connected to a pixel electrode made of indium tin oxide (ITO) or the like to perform display. The element substrate 121 is formed with an external connection terminal for receiving a signal input from the outside, and the external connection terminal is connected to the gate line and the source line.

On the element substrate 121, an oriented polymer resin film made of polyimide or the like is provided as an underlayer 126 of the seal 130 in an outer peripheral region 160 including a region 165 in contact with the seal. In addition, the alignment polymer resin film is provided in the display region 150 as the alignment film 125. The underlayer 126 is composed of an upper layer 126b of the underlayer modified by ultraviolet irradiation and a lower layer 126a of the unmodified underlayer.

Conductive paste (common paste) for conducting with the common electrode of the CF substrate 110 is applied to the four corners (outermost part outside the seal) of the TFT array substrate 120. In addition, as a method for establishing electrical connection between the TFT array substrate and the CF substrate, it is also possible to mix plastic beads or the like whose periphery is covered with a conductive material into a seal material described later. In this case, a plastic bead covered with a conductive material also functions as a spacer. Further, when the TFT array substrate 120 and the CF substrate 110 are bonded together, spacers (not shown) for keeping the distance between the two opposing substrates constant are scattered on the TFT array substrate 120. . As the spacer, silica (SiO ₂ ) or plastic spherical particles can be used.

(Underlayer reforming process)
Next, the process of modifying the upper layer of the underlayer will be described with reference to FIGS. 3-1 to 3-3 and FIG. 4 taking the CF substrate as an example.
FIGS. 3A to 3C are diagrams illustrating a modification process of the base layer 116 provided on the CF substrate, and FIG. 4 illustrates a surface state when the base layer 116 made of polyimide is modified. It is a cross-sectional schematic diagram shown. FIG. 4 is a schematic cross-sectional view showing the surface state of the upper layer of the base layer 116. In addition, the arrow in FIG. 3-2 has shown the ultraviolet-ray to irradiate. As shown in FIG. 3-2, UV light is applied to the underlayer 116 formed in the outer peripheral region 160 using the photomask 170 on the CF substrate 110 on which the alignment film 115 and the underlayer 116 as shown in FIG. Irradiate. The ultraviolet rays are irradiated for 30 to 600 seconds using ultraviolet rays having a wavelength of 100 to 300 nm and an energy of 5.0 to 7.0 eV. By irradiating with ultraviolet rays, the upper layer 116b of the underlayer is modified as shown in FIG. According to this, as shown in FIG. 4, in the area where the underlayer 116 is irradiated with ultraviolet rays, the C—C and C—H bonds with low bond energy between atoms are cut and oxidized by oxygen in the air. Is done. For this reason, oxygen atoms having lone electron pairs exist on the surface of the base layer 116. As a result, the polarization of the surface of the underlayer 116 is strengthened. In the case of a base layer made of polyimide, the contact angle of the base layer with respect to water before irradiation with ultraviolet rays is 90 to 110 °, whereas in a region in contact with the seal after irradiation with ultraviolet rays, The contact angle with respect to water can be 10 to 30 °. From the viewpoint of further preventing the sealing material from spreading wet, it is more preferable that the contact angle with water in the region in contact with the seal is 10 to 15 °. The contact angle is measured using a θ / 2 method, a tangent method, or the like. Similarly, in the TFT array substrate 120, the base layer is modified.

(Seal placement process)
Next, the seal arrangement process will be described taking the CF substrate as an example.
A sealing material is disposed on the underlayer 116 irradiated with ultraviolet rays shown in FIG. 2 by a method such as dispenser application or screen printing. The surface of the underlayer is activated by ultraviolet irradiation, oxygen atoms having lone electron pairs are present, and polarization is increased. Therefore, a highly polar site such as an alkyl group or a carbonyl group in the sealing material attracts oxygen atoms having a lone pair of electrons on the surface of the base layer 116, and the contact angle of the seal material with the base layer 116 becomes small. As a result, the force for retaining the sealing material on the base layer 116 is increased, and the spread of the sealing material can be suppressed. Further, the seal material includes a spacer made of glass fiber pieces, plastic spheres, etc., and the distance between the substrates when the TFT array substrate and the CF substrate are bonded together is made constant. Similarly, in the TFT array substrate, a sealing material is disposed on the base layer.

(Manufacturing process of liquid crystal display device)
The TFT array substrate 120 and the CF substrate 110 are provided at a predetermined interval between two substrates on which spacers are arranged, thereby forming a space for enclosing a liquid crystal material. A liquid crystal material is dropped into this space and bonded together by a sealing material applied in the manufacturing process of the CF substrate 110 and the TFT array substrate 120, and the liquid crystal material is sealed. As the sealing material, a material having strong ionicity can be preferably used. For example, an epoxy-based sealing material using an epoxy resin and a highly polar oligomer as a curing material thereof can be used. After encapsulating the liquid crystal material, provisional curing is performed by UV irradiation, followed by main curing at 200 ° C. In addition, the TFT array substrate 120 and the CF substrate 110 are a pair of substrates bonded with a conductive paste material containing carbon, silver, etc. in order to establish conduction between the common electrode of the CF substrate and the auxiliary capacitance of the TFT array substrate. Provided at the four corners (outermost outside the seal). Then, a liquid crystal display device is completed by mounting a polarizing plate, a driving driver and the like on the bonded liquid crystal display panel.

In the liquid crystal display device according to the first embodiment, when a predetermined voltage is applied to the gate electrode of the TFT via the gate line in each pixel and the TFT is turned on, the signal voltage is applied to the source electrode via the source line. By being applied, the liquid crystal capacitance and the auxiliary capacitance formed between the transparent electrode and the transparent electrode on the CF substrate side hold the charge flowing through the drain electrode. By utilizing the change in the alignment state of the liquid crystal molecules in the liquid crystal layer in accordance with the amount of charge, the light transmittance is adjusted to display an image.

The liquid crystal display device of the present invention can suppress the spread of the seal material and can widen the display area. Therefore, a narrow frame can be achieved. Further, in the liquid crystal display device of Embodiment 1, the frame can be narrowed only by adding a step of irradiating ultraviolet rays. In the first embodiment, the formation of the underlayer, the modification of the underlayer, and the arrangement of the sealing material are performed on both the TFT array substrate and the CF substrate. However, each step may be performed only on one substrate. Although not particularly limited, it is preferable to perform the respective steps on both substrates from the viewpoint of suppressing the wetting and spreading of the sealing material.

(Embodiment 2)
FIG. 5 is a schematic plan view showing the configuration of the CF substrate according to the second embodiment. In the CF substrate 210 according to the second embodiment, as shown in FIG. 5, a seal base layer 216 made of an oriented polymer resin film is disposed only on the three sides of the outer peripheral region outside the display region of the substrate 211. Yes. Further, in the TFT array substrate, a base layer is disposed in a region corresponding to the base layer 216 disposed on the substrate 211. On the side where the base layer is not disposed, an external connection terminal and a pixel are driven. A driver circuit and the like are provided. In the case of a liquid crystal display panel in which a driver circuit for driving pixels is arranged on the external connection terminal side of the TFT array substrate, a region where wiring for connecting to the external connection terminal is concentrated is formed on the external connection terminal side. Even if the area for arranging the seal is reduced, the display area cannot be widened. Therefore, an orientation polymer resin film may be provided on three sides of the four sides on which the seal is arranged. In this case, it is possible to reduce only the panel size without changing the size of the display area.

(Embodiment 3)
FIG. 6 is a schematic cross-sectional view of a display panel according to the third embodiment. As shown in FIG. 6, the liquid crystal display panel according to Embodiment 3 is configured by sealing a liquid crystal layer 331 sandwiched between a TFT array substrate 320 and a CF substrate 310 with a seal 330.

As shown in FIG. 6, in the CF substrate 310, a colored layer 313 made of a photosensitive material such as red, green, and blue is arranged on a substrate 311 made of alkali-free glass in a shape corresponding to the pixel region. . In a region where the colored layer 313 is not disposed, a light-shielding black matrix (BM) 312 made of metal chromium, acrylic photosensitive resin, or the like is disposed so as to surround the colored layer 313. A transparent electrode 314 made of indium tin oxide (ITO) or the like is provided on the coloring layer 313 and the BM 312. As shown in FIG. 6, an alignment film 315 made of polyimide or the like is provided on the transparent electrode 314 from the display region 350 to the outer peripheral region 360. In this case, the alignment film 315 includes an alignment film 315 a provided in the display region 350 and a base layer 316 provided in the outer peripheral region 360. A part of the surface of the base layer 316 is modified by being irradiated with ultraviolet rays, and an unmodified part 316a and a modified part 316b are formed. As a result, the contact angle of the region 365 where the seal is in contact with the seal material is smaller than the peripheral region 366 of the region where the seal is in contact.

The TFT array substrate 320 is configured by arranging an alignment film 125 and a base layer 126 on an element substrate 321. The element substrate 321 is provided with a TFT element on a substrate made of alkali-free glass or the like. The TFT element is provided at each intersection of a plurality of gate lines and source lines provided so as to extend in parallel to each other in an orthogonal direction. Then, the drain electrode of the TFT element is connected to a pixel electrode made of indium tin oxide (ITO) or the like to perform display. The element substrate 321 is formed with an external connection terminal for receiving an external signal input, and the external connection terminal is connected to the gate electrode and the source electrode. An alignment film 315 is provided in the display region 350 on the element substrate 321. The TFT array substrate 320 is composed of the element substrate 320 and the alignment film, and no seal underlayer is provided.

(Comparative Example 1)
FIG. 7 is a schematic plan view showing the arrangement of the alignment films on the CF substrate according to Comparative Example 1. FIG. 8 is a schematic cross-sectional view illustrating a configuration of a CF substrate according to Comparative Example 1. As shown in FIG. 8, the CF substrate 10 according to the comparative example has a colored layer 13 made of a photosensitive material such as red, green, and blue in a shape corresponding to a pixel region on a substrate 11 made of alkali-free glass. Has been placed. Further, a light-shielding black matrix (BM) 12 made of metallic chromium, acrylic photosensitive resin, or the like is disposed so as to sandwich the colored layer 13, and indium tin oxide (ITO) is disposed on the colored layer 13 and the BM 12. A transparent electrode 12 made of or the like is provided. As shown in FIGS. 7 and 8, the alignment film 15 is disposed in the display region 50 on the CF substrate 10, but the seal underlayer for suppressing the spread of the seal material is formed in the outer peripheral region 60. Not placed. Similarly, in the TFT array substrate, the base layer of the seal is not disposed in the outer peripheral region outside the display region. Therefore, between the area where the seal material is printed and the end of the color filter substrate so that the seal material does not bleed out to the outside of the panel due to the spread of the seal when the CF substrate and the TFT array substrate are bonded together. It is necessary to provide an interval. As a result, the frame area of the liquid crystal display device is widened.

3 is a schematic cross-sectional view illustrating a configuration of a liquid crystal display panel according to Embodiment 1. FIG. FIG. 3 is a schematic plan view showing an arrangement relationship between the alignment film of the CF substrate according to the first embodiment and a base layer of a seal. It is a cross-sectional schematic diagram which shows the structure of CF board | substrate with which the base layer is provided. It is a cross-sectional schematic diagram which shows the process of irradiating the surface of the base layer provided on the CF substrate with ultraviolet rays. It is a cross-sectional schematic diagram which shows that the surface of the base layer provided on the CF substrate is modified. It is a cross-sectional schematic diagram which shows the surface state of the upper layer of a base layer. 6 is a schematic plan view illustrating a configuration of a CF substrate according to Embodiment 2. FIG. 6 is a schematic cross-sectional view of a display panel according to Embodiment 3. FIG. 6 is a schematic plan view illustrating an arrangement of alignment films of a color filter substrate according to Comparative Example 1. FIG. 6 is a schematic cross-sectional view illustrating a configuration of a color filter substrate according to Comparative Example 1. FIG.

Explanation of symbols

10, 110, 310: Color filter (CF) substrates 11, 111, 311: Substrates 12, 112, 312: Black matrix (BM)
13, 113, 313: Colored layers 14, 114, 314: Common electrodes 15, 115, 125, 315, 325: Alignment films 116, 216, 316: Underlayer 116b, 126b: Upper layers 116a, 126a: Underlayer Lower layer 120, 320: thin film transistor (TFT) array substrate 121, 321: element substrate 130, 330: seal 131: bonding surface 150, 350: display region 160, 360: outer peripheral region 165, 365: regions 166, 366 in contact with the seal : Peripheral region 170: Photomask 315a: Alignment film 316a in display region: Unmodified portion 316b: Modified portion

Claims (5)

A display device having a pair of substrates disposed opposite to each other and a seal for bonding the pair of substrates in a region outside the display region,
The substrate has a base layer of the seal in a region in contact with the seal,
A display device, wherein a contact angle with a seal material in a region in contact with a seal is smaller than a contact angle with a seal material in a peripheral region in a region in contact with the seal. The display device has a liquid crystal layer sandwiched between a pair of substrates on the display region side of the seal, and has an alignment film on the display region of the substrate,
The display device according to claim 1, wherein the underlayer includes a material constituting the alignment film. The display device according to claim 1, wherein the base layer is modified in a region in contact with the seal. The display device according to claim 1, wherein the base layer is provided on each of the pair of substrates. A method of manufacturing the display device according to claim 1,
The manufacturing method includes a step of disposing a base layer of the seal in a region outside the display region of the substrate;
Modifying the region in contact with the underlayer seal;
Disposing a sealing material on the underlayer;
Bonding a pair of substrates;
And a step of solidifying the sealing material in this order.

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