JP2007140132A - Liquid crystal display device and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a liquid crystal display device where the liquid crystal panel will less likely to crack, when an external force is added to the liquid crystal panel during its use or the like. <P>SOLUTION: The liquid crystal display device 27 comprises the liquid crystal panel 10, which has a stuck substrate constituting of two sheets of transparent substrates 11, 12 stuck with a sealing material to each other and polarizing plates 13, 14 stuck to outside surfaces of the respective transparent substrates 11, 12 with an adhesive, and has a construction in which the liquid crystal panel 10 is contained, in a state of having the observation face side of the liquid crystal panel 10 bent into a protruding shape. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a liquid crystal display device comprising a liquid crystal panel having a bonded substrate in which two transparent substrates are bonded together with a sealing material, and a polarizing plate bonded to the outer surface of each transparent substrate with an adhesive, and the same It relates to a manufacturing method.

  The liquid crystal display device is further reduced in thickness, and the glass substrate used is also reduced in thickness. As a result, an external force such as vibration during use is applied to the liquid crystal panel, so that the liquid crystal panel is easily broken. Various methods have been proposed as countermeasures.

For example, Patent Literature 1 discloses a liquid crystal display device in which the thickness or strength per unit of a glass substrate on the display side is made larger than the thickness or strength of the glass substrate on the opposite side.
JP 2001-75079 A

  In the first place, most of the reasons why the liquid crystal panel in the display device breaks are the liquid crystal that is placed in a flat state when vibration or external force is applied to the liquid crystal panel by the user touching or holding the liquid crystal panel This is because the panel bends to the side opposite to the observation surface side, and the strength of the substrate cannot withstand this bending and breaks or comes into contact with other members such as a backlight on the back side of the liquid crystal panel.

  In particular, liquid crystal panels whose glass substrates are becoming thinner are mostly used outdoors such as mobile phones, but such mobile phones are located on the back side of LCD panels for display. Various circuit boards and components are mounted with high density even in a backlight as a light source and a liquid crystal panel that does not require a backlight. Therefore, when an external force is applied so that the liquid crystal panel bends toward the back side, the possibility of contact with these back side members increases and the risk of cracking increases.

  Therefore, an object of the present invention is to realize a liquid crystal display device that is less likely to accidentally break a liquid crystal panel during use. Another object of the present invention is to provide a manufacturing method thereof.

  In order to achieve the above object, the present invention includes a bonded substrate in which two light-transmitting substrates are bonded together with a sealing material, and a polarizing plate bonded to the outer surface of each light-transmitting substrate with an adhesive. In the liquid crystal display device including the liquid crystal panel, the liquid crystal panel is bent so as to be convex toward the observation surface.

  According to this configuration, when an external force that pushes the display surface is applied, the liquid crystal panel is easily cracked because the flat liquid crystal panel is conventionally pressed, but in the present invention, the liquid crystal panel is bent toward the display surface. Therefore, even if the display surface is pushed by an external force, the liquid crystal panel is flat at first and is not easily broken.

  The present invention also includes a liquid crystal panel having a bonded substrate in which two light-transmitting substrates are bonded together with a sealing material, and a polarizing plate bonded to the outer surface of each light-transmitting substrate with an adhesive. In the method of manufacturing a liquid crystal display device, the liquid crystal panel is housed in a state where the liquid crystal panel is bent so as to have a convex shape on the observation surface side.

  According to the present invention, when an external force that pushes the display surface is applied due to the observation surface side of the liquid crystal panel being bent so as to have a convex shape in a normal state, the liquid crystal panel first returns to a flat state. Since it bends, the distance which bends to the back side can be ensured, and it becomes difficult to break. Therefore, it is possible to realize a liquid crystal display device that is less likely to accidentally break the liquid crystal panel during use.

  Hereinafter, in order to explain the present invention, a TFT active matrix type color liquid crystal panel will be described as an example. However, the liquid crystal panel method is not particularly limited, and is applicable to other active matrix type and simple matrix type liquid crystal panels. can do.

  FIG. 1 is a cross-sectional view of a predetermined portion of a TFT active matrix type color liquid crystal panel 10. 11 and 12 are translucent substrates, which are a first transparent substrate and a second transparent substrate made of non-alkali glass or the like. Reference numerals 13 and 14 denote polarizing plates attached to the outside of the transparent substrates 11 and 12, respectively.

  The thickness of the transparent substrates 11 and 12 is preferably 0.5 mm or less in order to reduce the thickness of the liquid crystal panel. In particular, when a transparent substrate of 0.3 mm or less is used, there is a possibility that the substrate may break. Therefore, the present invention is very effective.

  For the polarizing plates 13 and 14, polyvinyl alcohol (PVA) / iodine, a polyethylene film, or the like can be used. For example, a PVA / iodine polarizing plate is a uniaxially stretched PVA polymer film on which iodine ions are adsorbed to produce a PVA deflection film, and a substrate film (for example, triacetyl cellulose) is pasted on the front and back of the PVA deflection film, A protective film (for example, polyethylene terephthalate or polyethylene) is laminated on one surface, and an acrylic adhesive and a release film are laminated on the other surface. Such polarizing plates 13 and 14 preferably have a thickness of 0.2 to 0.4 mm.

  A retardation plate may be provided between the polarizing plates 13 and 14 and the transparent substrates 11 and 12.

  Reference numeral 15 denotes a wiring made of a metal thin film, 16 denotes a drain electrode connecting the wiring 15 and a TFT (not shown), and 17 denotes an acrylic resin or the like formed on the wiring 15 or the first transparent substrate 11. An insulating film 18 is a pixel electrode made of a transparent conductive film for each pixel dot connected to the drain electrode 16 through a connection hole of the insulating film 17.

  Further, 19 is a color filter (CF) attached to the inside of the second transparent substrate 12 for each pixel dot, 20 is a black matrix for shielding a non-display portion, and 21 is on the pixel electrode 18 and will be described later. The alignment films are respectively applied on the counter common electrode 23.

  Reference numeral 22 denotes a counter common electrode made of a transparent conductive film formed on the color filter 19 and the black matrix 20. A sealing material 23 is formed over substantially the entire circumference of the second transparent substrate 12 and adheres the second transparent substrate 12 and the insulating film 17. The portion surrounded by the sealing material 23 is filled with the liquid crystal layer 24.

  Next, a manufacturing process of the liquid crystal display device including the liquid crystal panel 10 will be described. There are roughly three processes: an array process, a cell process, and a module process. The array process is an array substrate process in which the first transparent substrate 11 is processed to form the wiring 15, drain electrode 16, insulator 17, pixel electrode 18, TFT, and the like. As is well known, there is a separate process for forming a CF substrate on the second transparent substrate 12 side on which the color filter is formed.

  In the next cell process, after the surface treatment is performed on the previously completed array substrate and the CF substrate facing the array substrate, that is, the second transparent substrate 12, the two transparent substrates are assembled. In this step, liquid crystal is injected and sealed in the gap, and a polarizing plate is attached to both substrates.

  The last module process is the process of attaching the electronic circuit of the drive system so that the array / CF substrate can be electrically controlled, and the process of attaching the electronic components and materials such as the backlight as the light source But there is.

  For example, if a liquid crystal panel is used as a display unit of a mobile phone, various signals are exchanged that are installed in the casing of the mobile phone and electrically connected to other components in the mobile phone. become.

  At this time, in the present invention, the liquid crystal panel bent in a convex shape is fixed and stored on the display surface side which is the side observed by the user. In the embodiment, the second transparent substrate side constituting the liquid crystal panel 10 is the display surface side.

  Here, the above cell process will be described in more detail. First, the alignment film 21 is formed on the completed TFT array substrate. In this method, polyimide resin or the like is dissolved in a solvent and printed with a precision rubber plate or the like, or applied by a spinner method.

  Next, a groove (not shown) is formed on the alignment film 21 in order to determine the alignment direction of the liquid crystal molecules. Specifically, the alignment film 21 is rubbed while rotating a roller around which a long-legged cloth is wound. Next, the sealing material 23 is applied to the first transparent substrate 11 or the second transparent substrate 12 by screen printing. In order to keep the cell gap constant, spacer materials such as plastic beads are dispersed on the screen. As a spraying method, a method of applying a high voltage to the powdered spacer material and spraying with a force of static electricity (dry spraying) or the like can be used.

  As another means for keeping the cell gap constant, ribs having a constant thickness may be formed on the transparent substrate 11 or 12.

  Next, the two electrode substrates are precisely bonded together using an alignment mask pattern provided in advance. The bonded substrates are irradiated with heat and ultraviolet rays while being pressurized to improve the sealing degree, and the sealing material 23 is cured.

  Next, the waste sheet on the outer periphery of the bonded substrates is cut. In addition, for multi-chamfering in which several liquid crystal panels can be taken from the substrate, the chamfering, cutting and cutting are also performed simultaneously.

  Next, a liquid crystal material is injected into each empty cell by a vacuum type injection device. After injecting the liquid crystal material, an adhesive or the like is applied to the injection port of the cell, and the injection port is closed by heat or ultraviolet irradiation to complete a bonded substrate.

  Next, the polarizing plates 13 and 14 are bonded to the bonded substrate produced in the above process. Here, in the state of the bonded substrate before the polarizing plates 13 and 14 are bonded, due to the tension of the sealing material 23. The bonded substrate board may already be bent. In particular, there are many cases where the substrate is bent when a thin substrate is used.

  The bending direction varies depending on the arrangement of the sealing material, and is convex toward the first transparent substrate 11 or convex toward the second transparent substrate 12. If it is convex on the second transparent substrate 12 side, it is possible to use a liquid crystal panel because it is a convex liquid crystal panel on the second transparent substrate side by sticking the polarizing plate as it is.

  However, as shown in FIG. 2, the first transparent substrate 11 side may be convex. In this case, it must be convex toward the second transparent substrate 12 side.

  As a method therefor, there is a method using both polarizing plates 13 and 14 having different thicknesses. Specifically, a polarizing plate thinner than the polarizing plate 13 on the first transparent substrate 11 (array substrate) side is used for the polarizing plate 14 on the second transparent substrate 12 (CF substrate) side. Then, the polarizing plates 13 and 14 coated with the adhesive are pasted on the bonded substrate in the state shown in FIG. 2 while being pressed by a rubber roller or the like so that bubbles do not enter the transparent substrates 11 and 12, respectively. Subsequently, the polarizing plates 13 and 14 are attached by heating and pressing in the chamber. Then, the polarizing plates 13 and 14 and the adhesive are contracted by heating, the bonded substrate is deformed as shown in FIG. 3, and the second transparent substrate 12 side becomes convex. This deformation is caused by the fact that the thick polarizing plate has a stronger contraction force due to heat than the thin polarizing plate.

  Further, for example, there is a method of sticking both polarizing plates in a state where the bonded substrate is bent. Specifically, the polarizing plate 13 or 14 coated with an adhesive is applied with stress applied so that the second transparent substrate 12 side becomes a convex surface with the bonded substrate in the state of FIG. In this method, the transparent substrates 11 and 12 are attached while being pressed with a rubber roller or the like so that bubbles do not enter, and heated and pressurized in a chamber to complete the attachment of the polarizing plates 13 and 14. Then, the bonded substrate to which the polarizing plates 13 and 14 are bonded has a convex shape on the second transparent substrate 12 side as shown in FIG.

  Further, for example, there is a method for determining the order of attaching both polarizing plates 13 and 14. Specifically, the polarizing plate 14 to which the adhesive has been applied is attached to the bonded substrate in the state shown in FIG. 2 while being pressed with a rubber roller or the like so that bubbles do not enter the second transparent substrate 12, and heated in the chamber. Apply pressure to complete the attachment of the polarizing plate 14. Then, the polarizing plate 14 and the adhesive are contracted by heating, and the bonded substrate is maintained in a state where the first transparent substrate 11 side is convex as shown in FIG. Subsequently, the polarizing plate 13 to which the adhesive has been applied is pasted while being pressed by a rubber roller or the like so that air bubbles do not enter the first transparent substrate 11 to obtain the state shown in FIG. And it heats and pressurizes in a chamber, and the sticking of the polarizing plate 13 is completed. Then, the polarizing plate 13 and the adhesive shrink due to heating, and the bonded substrate is deformed as shown in FIG. 4 so that the second transparent substrate 12 side has a convex shape. Thus, the second transparent substrate 12 side can also be controlled to be a convex surface by a method in which the polarizing plate 14 is first attached, heated, and pressurized, and then the polarizing plate 13 is attached, heated, and pressurized.

  By these methods, the bonded substrate that is initially convex toward the first transparent substrate becomes the liquid crystal panel 10 that is controlled so that the display surface side (second transparent substrate side) is convex. . In addition, the conditions at the time of heating and pressurizing the polarizing plates 13 and 14 can be set to, for example, 50 ° C. and 0.5 MPa.

  In addition, since these methods maintain the state where the display surface side is bent in a convex shape, it is necessary to bend the liquid crystal panel 10 so that the surface side is bent in a convex shape when the liquid crystal panel 10 is fixed and stored. Since it is not, it can be fixed and stored easily. Further, there is no fear that the liquid crystal panel 10 is broken because it is bent too much when the liquid crystal panel 10 is bent.

  Thus, the liquid crystal panel 10 bent in a convex shape toward the display surface is assembled to the housing. FIG. 7 is a schematic cross-sectional view of the liquid crystal display device showing the state of the liquid crystal panel in the housing. The liquid crystal panel 10 is assembled to the housing 25 with the display surface side being convex, a window is formed in the housing 25 portion above the liquid crystal panel 10, and a transparent protective plate made of acrylic or the like in the window 26 is provided.

  When an external force is applied to the liquid crystal display device 27 in the direction in which the protective plate 26 is pushed (direction of arrow F), for example, when the user pushes the protective plate 26, the protective plate 26 is bent and the liquid crystal panel 10 is pushed. . FIG. 8 shows a schematic cross-sectional view of the liquid crystal display device 27 when the protective plate 26 is pushed. The liquid crystal panel 10 is pressed by the protective plate 26 and is in a flat state. Moreover, when the external force beyond this is applied, the liquid crystal panel 10 bends to the back side so that the polarizing plate 13 side becomes convex.

  As described above, when an external force in the direction of arrow F is applied, the liquid crystal panel is easily cracked because the flat liquid crystal panel is pushed in the prior art. Therefore, even if the display surface is pushed by an external force, the liquid crystal panel 10 is not easily cracked because the liquid crystal panel 10 first goes flat and then bends in the opposite direction. Accordingly, it is possible to realize the liquid crystal display device 27 that is less likely to accidentally break the liquid crystal panel 10 during use.

  For example, when the liquid crystal panel 10 is 2 inches, the deflection of the liquid crystal panel 10 (the maximum height from the horizontal plate to the liquid crystal panel 10 when placed on the horizontal plate) is preferably less than 0.1 mm. In addition, the above-described protective plate 26 is not necessarily required, and a configuration in which the polarizing plate 14 is exposed to the outside may be employed.

  The method for producing a liquid crystal display device of the present invention can be applied to a liquid crystal display device having polarizing plates on both outer surfaces of a liquid crystal panel. The present invention can be effectively used for a liquid crystal panel of about 2 inches. A liquid crystal panel of this size can be used for a mobile phone or the like.

It is sectional drawing of the predetermined part of a TFT active matrix type color liquid crystal panel. It is sectional drawing of a bonding board | substrate. It is sectional drawing of the bonding board | substrate which stuck the polarizing plate from which thickness differs. It is sectional drawing of the bonding board | substrate which stuck both polarizing plates in the state which bent the bonding board | substrate. It is sectional drawing of the bonding board | substrate which stuck and heated and pressurized the polarizing plate to the 2nd transparent substrate. It is sectional drawing of the bonding board | substrate which bonded the polarizing plate to the 1st transparent substrate. It is a schematic sectional drawing of the liquid crystal display device which shows the state of the liquid crystal panel in a housing | casing. It is a schematic sectional drawing of a liquid crystal display device when a protection board is pushed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal panel 11 1st transparent substrate 12 2nd transparent substrate 13, 14 Polarizing plate 23 Sealing material 27 Liquid crystal display device

Claims (6)

In a liquid crystal display device comprising a liquid crystal panel having a bonded substrate in which two light-transmitting substrates are bonded together with a sealing material, and a polarizing plate bonded to the outer surface of each light-transmitting substrate with an adhesive,
A liquid crystal display device, wherein the liquid crystal panel is bent so as to be convex toward an observation surface side.   2. The liquid crystal display device according to claim 1, wherein the thicknesses of the two polarizing plates are thinner on the observation surface side. Manufacture of a liquid crystal display device comprising a liquid crystal panel having a bonded substrate in which two light-transmitting substrates are bonded together with a sealing material, and a polarizing plate bonded to the outer surface of each light-transmitting substrate with an adhesive In the method
A method of manufacturing a liquid crystal display device, comprising storing the liquid crystal panel in a state in which the liquid crystal panel is bent so as to be convex on an observation surface side.   4. The method of manufacturing a liquid crystal display device according to claim 3, wherein an attaching order of the two polarizing plates is determined so that the liquid crystal panel has a convex shape on the observation surface side.   4. The method of manufacturing a liquid crystal display device according to claim 3, wherein the polarizing plates are bonded in a state where the bonded substrate is bent so that the liquid crystal panel is convex on the observation surface side.   4. The method of manufacturing a liquid crystal display device according to claim 3, wherein the thicknesses of the two polarizing plates are different so that the liquid crystal panel has a convex shape on the observation surface side.

Images