JP2007304274A - Liquid crystal display element and manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem occurring when a liquid crystal display element with a black matrix is manufactured by filling a liquid crystal using a one drop filling process then curing UV-curing frame-shaped sealing material with UV irradiation, the problem being insufficient curing of the frame-shaped sealing material due to an insufficient UV irradiation level resulting in reduction in the reliability of the liquid crystal display element. <P>SOLUTION: A peripheral edge part of a first black matrix enclosing a display region is set inside the frame-shaped sealing material, a frame-shaped second black matrix formed along the frame-shaped sealing material and composed of a light shielding material is formed on the outer surface of a front substrate, and a width WSM of a frame shaped part of the frame-shaped sealing material and a width WBM of a frame-shaped part of the second black matrix are so set as to satisfy WBM>WSL. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  According to the present invention, a pair of substrates are fixed to each other with a predetermined gap through a frame-shaped sealing material, and liquid crystal is sealed between both substrates inside the frame-shaped sealing material. The present invention relates to a display element, and in particular, a black matrix that surrounds a large number of display pixel groups formed inside the frame-shaped sealing material and is provided along the frame-shaped sealing material. The present invention relates to a liquid crystal display device having

  In an active matrix type liquid crystal display element which is one type of liquid crystal display element, a switching element is provided in each of a plurality of pixels arranged in a matrix. A typical switching element is a thin film transistor (TFT).

  Note that an active matrix type liquid crystal display device using a thin film transistor is known, for example, from Patent Document 1. A configuration in which the periphery of the pixel electrode is covered with a light shielding film made of resin (hereinafter also referred to as a black matrix) is known from Patent Document 2, Patent Document 3, and Patent Document 4.

  In the liquid crystal display element, for example, a pair of substrates each having a display pixel electrode and an alignment film laminated on the inner surface are disposed so that the inner surfaces face each other with a predetermined gap therebetween, and the pair of substrates is disposed between the pair of substrates. After laminating both substrates with a frame-shaped sealing material provided with a cutout part in part as a liquid crystal sealing port on the peripheral edge of the liquid crystal, it is placed inside the sealing material by a vacuum injection method through the liquid crystal sealing port. After the liquid crystal is sealed, the liquid crystal sealing port is sealed.

  Further, a polarizing plate is attached to the outside of both the substrates, a backlight for supplying light to the liquid crystal display element is disposed below the liquid crystal display element, and a driving circuit board for driving the liquid crystal display element is provided as the liquid crystal display element Each of these members and a frame-shaped body made of a molded product that holds these members are housed in a metal shield case (frame) or the like having a display window, and the liquid crystal. A display device is formed.

JP-A-5-257142 Japanese Patent Laid-Open No. 4-342229 JP-A-5-72540 JP 11-352500 A

  In recent years, the spread of liquid crystal display elements to small portable devices such as mobile phones has been remarkable, but with the widespread use, the demand for lower prices of liquid crystal display elements has become increasingly severe. In order to meet this requirement, Japanese Patent No. 3210109 proposes a dropping injection method for the purpose of shortening the injection process instead of the reduced pressure injection method (also referred to as vacuum injection method). However, in this case, the thermosetting type cannot be used as the sealing material, and only the ultraviolet curable type can be used.

  On the other hand, in the liquid crystal display element, as disclosed in Patent Documents 1 to 4, the black matrix is provided so as to surround each pixel electrode so as to clarify the outline of each pixel and improve the contrast. In addition, a black matrix is also formed in the peripheral region of the substrate of the liquid crystal display element on which the frame-shaped sealing material is disposed, and the light from the backlight passes through the sealing material on the peripheral portion of the substrate of the liquid crystal display element. In order to prevent leakage to the display surface side. When light leakage occurs, the display contrast is lowered at the periphery of the display surface, and the display quality is remarkably deteriorated. In particular, when displaying bright characters, graphics, etc. on a dark display surface, it is greatly affected by this light leakage, which is a problem.

  However, if a black matrix is also formed in the peripheral region of the substrate of the liquid crystal display element in which the frame-shaped sealing material is arranged in this way, the ultraviolet curable sealing material used when the above-described dripping injection method is adopted. There was a risk that the irradiation amount of the ultraviolet rays would be insufficient, the sealing material would not be sufficiently cured, and the reliability of the liquid crystal display element would be significantly reduced.

  An object of the present invention is to provide a liquid crystal display element capable of adopting a dropping injection method that enables a shortening of the manufacturing process for liquid crystal encapsulation without deteriorating display quality and reliability of the liquid crystal display element, and its manufacture It is to provide a method.

  The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

  The outline of typical inventions among inventions disclosed in this document will be described as follows.

  (1) A transparent first substrate, a second substrate facing the transparent first substrate with a predetermined gap, and an ultraviolet curing material, the first substrate and the second substrate. A frame-shaped sealing material sandwiched between, a liquid crystal composition sealed inside the frame-shaped sealing material, and at least one of the first substrate and the second substrate The plurality of electrodes provided define a plurality of display pixels formed between the first substrate and the second substrate, and outlines of the plurality of display pixels, and the plurality of displays. In a liquid crystal display element composed of a first black matrix made of a light-shielding material formed so as to surround a display area made up of pixels, the peripheral edge of the black matrix surrounding the display area is inside the frame-shaped sealing material There is the frame shape on the outer surface of the first substrate. A frame-shaped second black matrix made of a light-shielding material and formed along the seal material, the width WSM of the frame-shaped portion of the frame-shaped seal material, and the frame-shaped portion of the second black matrix The width WBM satisfies the following relationship: WBM> WSL

  (2) The liquid crystal display element according to (1), wherein the ultraviolet curable material forming the frame-shaped sealing material contains a black pigment.

  (3) In the liquid crystal display element according to (2), the black pigment is a titanium black pigment.

  (4) A transparent first substrate, a second substrate facing the transparent first substrate with a predetermined gap, and an ultraviolet curing material, the first substrate and the second substrate. A frame-shaped sealing material sandwiched between, a liquid crystal composition sealed inside the frame-shaped sealing material, and at least one of the first substrate and the second substrate The plurality of electrodes provided define a plurality of display pixels formed between the first substrate and the second substrate, and outlines of the plurality of display pixels, and the plurality of displays. In a method of manufacturing a liquid crystal display element including a first black matrix made of a light-shielding material formed so as to surround a display area composed of pixels, a peripheral seal of the black matrix surrounding the display area is formed into the frame-shaped sealing material The frame-shaped sealing material is formed inside After curing by irradiation, a frame-shaped second black matrix made of a light-shielding material along the frame-shaped sealing material is formed on the outer surface of the first substrate, and a frame of the frame-shaped sealing material A method for manufacturing a liquid crystal display element, wherein the width WSM of the shape portion and the width WBM of the frame shape portion of the second black matrix are set to the following relationship.

WBM> WSL
(5) In the liquid crystal display element according to (4), a black pigment is contained in the ultraviolet curable material forming the frame-shaped sealing material.

  (6) In the liquid crystal display element according to (4), the black pigment is a titanium black pigment.

  According to the present invention, it is possible to shorten the injection process for liquid crystal encapsulation in a cell formed by a pair of opposing substrates and a frame-shaped sealing material sandwiched between peripheral edges of the pair of substrates. The dropping injection method can be adopted, and the display quality and the reliability of the liquid crystal display element can be secured.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, parts having the same function are given the same reference numerals, and repeated explanation thereof is omitted.

  In the drawings attached to this specification, for the sake of simplicity, the illustration of elements such as a substrate, electrodes formed on the substrate, electronic elements, electrical wiring, and external lead electrode terminals from them is omitted and clearly shown. For the sake of simplicity, each element in the drawing may be exaggerated and drawn using a scale ratio different from that of an actual display element or device.

  Prior to the description of the embodiment according to the present invention, a method for encapsulating liquid crystal in a liquid crystal display element using an ultraviolet curable sealant by using a dropping injection method will be briefly described in accordance with Japanese Patent No. 3210109. explain. FIG. 1 is a perspective view of a single substrate 10 for producing nine liquid crystal display elements for small portable devices such as mobile phones. Nine frame-shaped sealing materials 20 are formed on the substrate 10. In practice, a plurality of pixel electrodes, switching elements provided for each pixel electrode, wirings electrically coupled to these, and liquid crystal molecules are aligned inside each frame-shaped sealing material 20. An alignment film for the purpose is provided, but the illustration is omitted for simplification. The liquid crystal 30 is dropped inside the frame-shaped sealing material 20 using a dispenser 50.

  2a is a cross-sectional view taken along line IIa-IIa of one of the frame-shaped sealing materials 20 in FIG. Taking the part of this single sealing material 20 as an example, the assembly process of one liquid crystal display element will be described below. FIG. 2b shows a state in which the other substrate 40 is superimposed on the sealing material 20 in FIG. 2a and the liquid crystal 30 in the inside thereof, and then the substrates 10 and 40 are pressed so that the substrate 10 and the substrate 40 face each other at a predetermined interval. (For this purpose, a spacer or the like is used but not shown.) FIG. Next, as shown in FIG. 2 c, the sealing material 20 is irradiated with ultraviolet rays to cure the sealing material 20 and fix the substrate 10 and the substrate 40 together.

  3a is a plan view of the liquid crystal display device according to the first embodiment of the present invention, and FIG. 3b is a cross-sectional view of the liquid crystal display device of FIG. 3a taken along line IIIb-IIIb. The method of enclosing the liquid crystal by the dropping injection method has been described with reference to FIGS. 1 and 2a to 2c. The cross-sectional view shown in FIG. 3b corresponds to the cross-sectional view shown in FIG. 2c.

  3a and 3b, reference numeral 110 denotes a back substrate of the liquid crystal element, 140 denotes a front substrate of the liquid crystal element, 130 denotes a liquid crystal composition, 120 denotes a frame-shaped ultraviolet curable sealant, and 150 defines a pixel outline. Black matrixes PR, PG, and PB provided with a large number of openings indicate red primary, green primary, and blue primary color display pixels provided in the openings of the black matrix 150. Reference numeral 160 denotes an electrical wiring that is provided for each display pixel and is coupled to a pixel circuit (not shown) including a switching element for driving the display pixel. Reference numeral 170 indicates an external lead electrode terminal formed at the end of the electrical wiring.

  For simplicity, the pixel electrode formed on at least one of the front substrate 140 or the rear substrate 110, the pixel circuit including the switching elements provided on the rear substrate 110 corresponding to each pixel, and the front substrate 140 Elements such as the three primary color filters that are formed are not shown in FIGS. 3a and 3b.

  3c is an enlarged view of a portion A in FIG. 3b, and FIG. 3d is a cross-sectional view taken along line IIId-IIId in FIG. 3c. In FIG. 3c, color filters CFR, CFG, and CFB corresponding to red primary color, green primary color, and blue primary color are embedded in openings provided in the black matrix 150 on the front substrate 140, respectively. When the present embodiment is applied to a twisted nematic type liquid crystal display panel, it is made of ITO (Indium-Tin-Oxide) or the like via an overcoat film or an overcoat film. The transparent electrode film is formed on the black matrix 150 and the color filters CFR, CFG, and CFB, but the illustration thereof is omitted in FIG. 3c. Note that when the present embodiment is applied to an in-plane-switching type liquid crystal display panel, the transparent electrode film is unnecessary.

The rear substrate 110 is provided with a pixel circuit 180 that is provided corresponding to each of the display pixels PR, PG, and PB and that includes a switching element for driving the corresponding display pixel. An electric wiring 16 is coupled to 180, and an external extraction electrode terminal 170 is coupled to an end of the electric wiring. An insulating layer 190 made of, for example, SiN or SiO ₂ is provided under the layer where the electrical wiring 16 is formed, and a light-shielding metal layer made of, for example, Al or Cr, for example, is provided under the insulating layer 190. 200 is formed.

  3d is a cross-sectional view taken along line IIId-IIId of FIG. As shown in FIG. 3d, the light shielding metal layer 200 is formed with a width of, for example, 5 to 10 microns so as to shield the gap between the electrical wiring 160 and the electrical wiring 160.

  PR, PG, and PB indicate red primary color, green primary color, and blue primary color display pixels provided in the openings of the black matrix 150. Reference numeral 160 denotes an electrical wiring that is provided for each display pixel and is coupled to a pixel circuit (not shown) including a switching element for driving the display pixel. Reference numeral 170 indicates an external lead electrode terminal formed at the end of the electrical wiring.

  As described with reference to FIG. 3d, the back substrate 110 is provided with the electrical wiring 160 and the light shielding metal layer 200 that shields the gap between the electrical wiring 160 and the electrical wiring 160. The ultraviolet irradiation for curing 120 cannot be performed from the back substrate 110 side.

  Therefore, in this embodiment, the peripheral edge of the black matrix 150 formed on the front substrate 140 is not overlapped with the frame-shaped ultraviolet curable sealing material 120, and the outer edge of the black matrix 150 is frame-shaped. It is formed so as to be inside the ultraviolet curable seal 120. Therefore, after the liquid crystal composition 130 is injected into the frame-shaped sealing material 120 between the back substrate 110 and the front substrate 140 by the dropping injection method, as described with reference to FIG. As shown, when the frame-shaped ultraviolet curable seal 120 is irradiated with ultraviolet rays in order to cure the frame-shaped ultraviolet curable seal 120, the ultraviolet rays are not obstructed by the black matrix 150 and the ultraviolet curable seal material is used. Therefore, the ultraviolet curable seal 120 is sufficiently cured, and a highly reliable liquid crystal display element is obtained.

  Here, the following are proposed as the ultraviolet curable sealing material.

  80 parts by weight of epoxy acrylate of bisphenol F epoxy resin, 20 parts by weight of RE203 (manufactured by Nippon Kayaku Co., Ltd .; epoxy equivalent 233 g / eq, ethylene oxide-added bisphenol S type epoxy resin) as an epoxy resin, radical-generating photopolymerization initiator 3,6-bis (2-methyl-2-morpholinopropionyl) -9-n-octylcarbazole (manufactured by Asahi Denka Kogyo Co., Ltd., Adekaoptomer N-1414), boric acid ester 2,2- 0.5 parts by weight of oxybis (5,5-dimethyl-1,3,2-dioxaborinane), 0.5 parts by weight of PN-80 (manufactured by Nippon Kayaku Co., Ltd., phenol novolac resin), aminosilane coupling agent (N- β (aminoethyl) γ-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Silicone, KBM-603) 1.3 layers Part was heated and dissolved at 90 ° C., to obtain a resin solution. After cooling to room temperature, isophthalic acid dihydrazide (trade name IDH-S; finely pulverized jet mill pulverized grade made by Otsuka Chemical Co., Ltd., melting point 224 ° C., active hydrogen equivalent 48.5 g / eq, average particle size 1.7 μm, maximum particle size 7 μm) 10 parts by weight, alumina (CAI Kasei Co., Ltd., SPC-Al, average particle size 1.0 μm) 13 parts by weight, rubber (Kureha Chemical Industries, Paraloid EXL-2655), A UV sealant obtained by dispersing and kneading 3.9 parts by weight of an average particle size of 0.2 μm with a mill is considered effective.

  As a method for forming the black matrix 150, for example, an organic resin such as acrylic, epoxy, or polyimide resin containing carbon black or a black organic pigment is applied in a pattern on the transparent glass substrate 140. There is a way to do it.

  As described above, with respect to the liquid crystal element in which the UV curable seal 120 is cured and sufficiently hermetically sealed, the front substrate 140 of the front substrate 140 is shown in FIG. A frame-shaped external black matrix 150EX having a shape along the four sides is formed. Similarly to the case of the matrix 150, the frame-like external black matrix 150EX is made of, for example, an organic resin such as acrylic, epoxy, or polyimide resin containing carbon black or a black organic pigment. It can be formed by applying a pattern on the glass substrate 140.

  The width WBM (see FIG. 3c) of the frame-shaped external black matrix 150EX and the width WSL (see FIG. 3c) of the frame-shaped ultraviolet curable seal 120 need to be set so as to satisfy the following relationship. is there.

WBM> WS
In the present embodiment having the above-described configuration, the frame-shaped external black matrix 150EX is not yet formed on the front substrate 140 at the time when the ultraviolet curable seal 120 is cured. Accordingly, after the liquid crystal composition 130 is injected into the frame-shaped sealing material 120 between the back substrate 110 and the front substrate 140 by the dropping injection method, as described with reference to FIG. 2c, as shown in FIG. 3c. When the frame-shaped ultraviolet curable seal 120 is irradiated with ultraviolet rays in order to cure the frame-shaped ultraviolet curable seal 120, the ultraviolet rays are not disturbed by either the black matrix 150 or the black matrix 150EX. Since it can reach the curable sealing material 120, the ultraviolet curable seal 120 is sufficiently cured, and a highly reliable liquid crystal display element is obtained.

  Next, the optical characteristics required for the frame-shaped ultraviolet curable sealing material 120 are studied. It is beneficial to provide the ultraviolet curable sealing material 120 with the same light shielding characteristics as the black matrix 150. For example, it is preferable to increase the optical density (OD). However, when the optical density OD is excessively large, there is a problem that the ultraviolet curable sealing material is not cured. The value of the optical density OD required for the ultraviolet curable sealant 120 depends on the distance CG (see FIG. 3b) between the back substrate 110 and the front substrate 140, and should be set in consideration of this. Is preferred.

  As an example of a method for adjusting the optical density, there is a method of adding a titanium black pigment to an ultraviolet curable sealing material. This titanium black pigment is described in detail in JP-A No. 58-180413.

It is a perspective view for demonstrating dripping of the liquid crystal enclosed in the liquid crystal display element which uses a frame-shaped ultraviolet curing sealing material. It is sectional drawing which shows the state by which the liquid crystal sealed was dripped on the back substrate in the creation process of the liquid crystal display element which uses a frame-shaped ultraviolet curing sealing material. FIG. 5 is a cross-sectional view showing a state where a back substrate and a front substrate sandwiching liquid crystal to be sealed are pressed and face each other at a predetermined interval in a liquid crystal display element manufacturing process using a frame-shaped ultraviolet curable sealing material. . It is sectional drawing explaining the process of irradiating an ultraviolet-ray and hardening a sealing material, and adhering a front substrate and a back substrate in the creation process of the liquid crystal display element using a frame-shaped ultraviolet curing sealing material. It is a top view for demonstrating the liquid crystal display element by the 1st Example of this invention. FIG. 3b is a cross-sectional view of the liquid crystal display element of FIG. 3a along line IIIb-IIIb. It is the A section enlarged view of FIG. 3b. FIG. 3c is a sectional view taken along line IIId-IIId in FIG. 3c.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 20 ... Frame-shaped sealing material, 30 ... Liquid crystal, 40 ... Board | substrate, 50 ... Dispenser, 110 ... Back substrate, 120 ... Frame-shaped ultraviolet curing sealing material, 130 ... Liquid crystal composition, 140 ... Front substrate 150 ... Black matrix, 150EX ... External black matrix, 160 ... Electric wiring, 170 ... External electrode terminal, 180 ... Pixel circuit, 190 ... Insulating layer, 200 ... Light shielding metal layer, ..., CFR ... Red primary color filter, CFG ... green primary color filter, CFB ... blue primary color filter, PR ... red primary color display pixel, PG ... green primary color display pixel, PB ... blue primary color display pixel.

Claims (6)

A transparent first substrate;
A second substrate facing the transparent first substrate with a predetermined interval;
A frame-shaped sealing material made of an ultraviolet curable material and sandwiched between the first substrate and the second substrate;
A liquid crystal composition sealed inside the frame-shaped sealing material;
A plurality of display pixels formed between the first substrate and the second substrate by a plurality of electrodes provided on at least one of the first substrate and the second substrate; ,
In a liquid crystal display element comprising a first black matrix made of a light-shielding material that defines the outline of each of the plurality of display pixels and surrounds a display region made of the plurality of display pixels.
A peripheral portion of the black matrix surrounding the display area is inside the frame-shaped sealing material;
A frame-shaped second black matrix made of a light-shielding material, formed along the frame-shaped sealing material on the outer surface of the first substrate;
The width WSM of the frame-shaped portion of the frame-shaped sealing material and the width WBM of the frame-shaped portion of the second black matrix satisfy the following relationship.
WBM> WSL   2. The liquid crystal display element according to claim 1, wherein a black pigment is contained in the ultraviolet curable material forming the frame-shaped sealing material.   The liquid crystal display element according to claim 2, wherein the black pigment is a titanium black pigment. A transparent first substrate;
A second substrate facing the transparent first substrate with a predetermined interval;
A frame-shaped sealing material made of an ultraviolet curable material and sandwiched between the first substrate and the second substrate;
A liquid crystal composition sealed inside the frame-shaped sealing material;
A plurality of display pixels formed between the first substrate and the second substrate by a plurality of electrodes provided on at least one of the first substrate and the second substrate; ,
In the method of manufacturing a liquid crystal display element comprising a first black matrix made of a light-shielding material and defining a contour of each of the plurality of display pixels and surrounding a display region made of the plurality of display pixels.
Forming a peripheral portion of the black matrix surrounding the display area inside the frame-shaped sealing material;
After the frame-shaped sealing material is cured by ultraviolet irradiation, a frame-shaped second black matrix made of a light-shielding material along the frame-shaped sealing material is formed on the outer surface of the first substrate,
A method for manufacturing a liquid crystal display element, wherein the width WSM of the frame-shaped portion of the frame-shaped sealing material and the width WBM of the frame-shaped portion of the second black matrix are set as follows.
WBM> WSL   The method for manufacturing a liquid crystal display element according to claim 4, wherein the ultraviolet curable material forming the frame-shaped sealing material contains a black pigment. The method for manufacturing a liquid crystal display element according to claim 5, wherein the black pigment is a titanium black pigment.

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