JP2002072928A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain natural large-screen images having obscure junctures between liquid crystal panels 2 and 2 by preventing the scattering of the light generated in the junctures between the liquid crystal panels 2 and 2 of a liquid crystal display device of a multipanel system which realizes the images of the large screen by connecting the plural liquid crystal panels 2 and 2. SOLUTION: Chamfered parts 2b are formed on the end face 2c side in the junctures between the liquid crystal panels 2 and 2, by which the internal stress generated in adhesives 9 by accompanying the effective shrinkage of the adhesives 9 connecting the liquid crystal panels 2 and 2 to each other and therefore cracks are not formed and the scattering of the light caused by these cracks can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an AV (Audio Visu
al) It relates to a display device used for a device or an OA (Office Automation) device.

In recent years, there has been an increasing demand for weight reduction, thinning, low power consumption, high definition, and a large screen for display devices used for home televisions used as AV equipment and OA equipment. I have. For this reason, CRT (Cathode-R
ay Tube) display, LCD (Liquid Crystal Displa)
y), plasma display, EL (Electro Luminesce
Display devices such as (nt) displays and LED (Light Emitting Diode) displays have also been developed to promote the above-mentioned improvements, and some of them have been put into practical use.

[0003] Particularly, at home, the role of television as entertainment is increasing. Even considering the current TV sales situation, the price per inch has been gradually decreasing, but it is gradually shifting to larger TVs. Is a mandatory requirement.

Similarly, in the business field, clear images can be obtained not only in still images but also in moving images, which can be easily handled, and can be applied to presentations using a computer. The display device as described above has been used also from the viewpoint of being obtainable, and further enlargement is expected.

[0005] In particular, the liquid crystal display device can be remarkably thinned in the depth direction, that is, the thickness, as compared with other display devices. In recent years, it has been used in various fields because of easy full-color display, and expectations for a larger screen than other display devices have been increasing.

In the above-mentioned enlargement of the screen, if the resolution per screen is the same, the image becomes very noticeable. Therefore, it is necessary to improve the resolution while improving the image quality of the video source. In a liquid crystal display device, an image is formed by a large number of display elements which are integrally formed at the same time and can be independently controlled. Improving the resolution is nothing less than increasing the number of the display elements.

However, the reduction in the defect rate of each display element alone in the manufacturing process has almost reached a plateau at present, and a dramatic progress cannot be expected. Therefore, increasing the number of display elements with an increase in the screen size of the liquid crystal display device degrades the manufacturing yield of the entire display device at an accelerated rate, and as a result, the liquid crystal display device with a large screen and high image quality However, it was difficult to increase the production amount, and it became very expensive.

In order to solve the above-mentioned problem, as shown in FIG. 2 of the present embodiment, a so-called multi-panel display type liquid crystal display for connecting a plurality of liquid crystal display devices to display one image. A method of realizing a large screen by using an apparatus has been adopted. By using such a method, even if the defect rates of a single display element are equal, the defect rate of the entire display device is dispersed, and the yield of the entire liquid crystal display device can be improved.
An increase in cost per unit area can be suppressed, and a low-cost, large-screen, high-quality liquid crystal display device can be obtained.

[0009]

When the above-mentioned multi-display type liquid crystal display device is formed, a reinforcing substrate 3 is used as shown in FIG. And a plurality of liquid crystal panels 2
Can be formed adjacent to each other to form a liquid crystal display device having a larger area.

However, when a plurality of liquid crystal panels 2 are joined to form the liquid crystal display device 1, the end face 2c of the liquid crystal panel 2 is in contact with a medium having a different refractive index (for example, air). Then, light refraction occurs there. Also, if the end face 2c is roughened during processing, light refraction and
Scattering occurs. These cause the connection between the liquid crystal panels 2 to stand out. Accordingly, the refractive index of the adhesive for bonding the reinforcing substrate 3 and the liquid crystal panel 2 at the time of curing is equal to the refractive index of the adhesive used to connect the liquid crystal panels 2 and 2 at the time of curing, and It is preferable that the refractive index is substantially equal to the refractive index of the reinforcing substrate 3 or the substrate constituting the liquid crystal panel 2. Thereby, refraction and scattering of light as described above can be avoided.

However, when the adhesive 9 is used as shown in FIG.
A crack 9a is generated along the vicinity of the edge of No. 2. This corresponds to the edge 2a of the liquid crystal panel 2 (FIG. 12).
In the vicinity of (a), stress concentration occurs due to the curing shrinkage of the adhesive 9, so that a slight impact or the like causes the crack 9a to be generated or grown. When light passes through such a crack 9a, it is scattered, which causes the connection between the liquid crystal panels 2 to stand out. Further, along with the above-mentioned curing shrinkage, partial peeling 9b may occur between the end face 2c of the liquid crystal panels 2 and the adhesive 9, and the light scattering as described above may occur. . On the other hand, if the surface accuracy of the end face portion 2c is rough, the adhesive 9 does not sufficiently penetrate into every corner of the unevenness of the end face portion 2c. Bubbles may remain, which also results in light scattering.

In other words, in order to obtain a natural large-screen image, it is necessary to prevent the above-mentioned cracks 9a, peeling 9b and bubbles from being generated, and to generate light scattering that makes the seams between the liquid crystal panels 2 stand out. Need to be stopped.

An object of the present invention is to provide a display device which forms a large screen by connecting a plurality of panels as described above and which realizes a natural large screen without scattering of light at a joint between the panels. To provide.

[0014]

In order to solve the above-mentioned problems, the present invention provides a display device of a multi-panel type which performs a large-screen display by connecting a plurality of display panels adjacently using an adhesive. The display panel is characterized in that the sectional end accuracy of the connection-side end face of the display panel is 2 μm or less. According to the above configuration, the wettability of the adhesive on the connection-side end surface of the display panel is improved, so that it is possible to prevent air bubbles from being mixed into the interface between the connection-side end surface and the adhesive at the connection portion of the display panel. it can. Thus, it is possible to provide a display device that realizes a natural large screen without causing light scattering at a joint between panels.

Further, in a multi-panel display device in which a plurality of display panels are connected adjacently by using an adhesive to perform a large-screen display, the accuracy of the sectional plane position of the connection-side end face of the display panel is set to 10 μm or less. It is characterized by:
According to the above configuration, the connection width between the display panels can be reduced.

Further, in a multi-panel display device in which a plurality of display panels are connected adjacently by using an adhesive to perform a large-screen display, an interval between adjacent panels is set to 50 μm or less. According to the above configuration, since the distance between the adjacent display panels is set to 50 μm or less, the absolute value of the volume shrinkage accompanying the curing shrinkage of the adhesive becomes small, and acts on the adhesive during curing. The value of the internal stress becomes smaller than the intermolecular bonding force of the cured adhesive. As a result, the occurrence of cracks in the adhesive at the edge portion can be prevented, and the internal stress becomes smaller than the adhesive force between the adhesive and the display panel, whereby the occurrence of peeling can be prevented.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment 1] An embodiment of the present invention will be described with reference to FIGS.
It is as follows. As shown in FIG. 2, a liquid crystal display device 1 according to the present embodiment is a direct-view type liquid crystal display device, and an active matrix is provided on a lower surface of a reinforcing substrate 3 having a size covering the entire display screen of the liquid crystal display device 1. In addition to disposing the liquid crystal panels 2.2 of the mold type, polarizing plates 8.8 described later are provided vertically so as to sandwich the reinforcing substrate 3 and the liquid crystal panels 2.2. 1 includes a backlight such as a cold cathode tube (not shown), a driver for controlling an image signal to be displayed, and the like. The liquid crystal panels 2 are controlled in accordance with the image information, and the light of the backlight is modulated, so that the image information input to the liquid crystal panel 2 can be recognized.

As shown in FIG. 3, the liquid crystal panel 2 has an active matrix type liquid crystal panel structure using a generally well-known matrix active element. That is, in order to eliminate crosstalk between scan electrodes generated in a simple matrix, a switch for completely cutting off an unrelated signal when not selected is provided in each pixel. This switch is called an active element, and this method is called an active matrix type. As the active element, an element called a so-called diode having two terminals or an element called a transistor having three terminals is used.

On a first substrate 10 composed of a glass substrate, a scanning electrode 14, a data electrode 13, and TFTs 16 arranged at intersections of those electrodes (Thin Film Tran)
sistor) and the pixel electrodes 15 are formed. TFT1
Reference numeral 6 denotes a field-effect transistor using a semiconductor thin film such as amorphous silicon (a-Si: H) or polycrystalline silicon (p-Si), and controls supply of an image signal to the pixel electrode 15. The pixel electrode 15 is formed of a transparent conductive film such as ITO (indium tin oxide) when used as a transmissive display device, or a reflective conductive film such as Al when used as a reflective display device.

On the other hand, on the second substrate 11, a common electrode 12
Are formed. When color display is performed, R (red), G (green), and B corresponding to each pixel electrode are used.
A (blue) color filter 4 and a black matrix 5 for separating each pixel are formed. The black matrix 5 is provided to block light from entering the gaps between the pixel electrodes 15 and the TFT area, and is formed so as to cover the periphery of each pixel electrode 15. This is because if light is transmitted through areas other than the pixel electrodes 15, the quality of the black display state is degraded and the contrast is reduced, and when light is incident on the TFT 16, a leak current is generated in the TFT channel by light excitation, This is because the display quality is reduced. The black matrix 5 may be provided not on the second substrate 11 side but on the first substrate 10 side.

To form the liquid crystal panel 2, the first substrate 10 and the second substrate 11 are connected to the pixel electrode 15 and the common electrode 1.
2 are opposed to each other via a sealing material 6 shown in FIG. 2 and a liquid crystal 7 is sealed between the first substrate 10 and the second substrate 11. Then, as shown in the figure, when joining the liquid crystal panels 2, an adhesive 9 serving as a refractive index adjusting material is filled into a connection portion between the liquid crystal panels 2. If the adhesive 9 does not have a refractive index equivalent to that of the liquid crystal panel 2, light is scattered due to unevenness of the end faces of the first substrate 10 and the second substrate 11 constituting the liquid crystal panel 2, which may cause a connection portion to be conspicuous. Become. Further, it is preferable that the adhesive 9 is also used when bonding the joined liquid crystal panels 2 and the reinforcing substrate 3 together. Also in this case, the reinforcing substrate 3 and the second substrate 11
This is because if light is reflected at the interface with, it will cause a decrease in contrast during display.

In the present embodiment, a glass substrate (Corning 7059) having a refractive index of 1.53 is used as the material of the first substrate 10 and the second substrate 11, so that the adhesive 9 has a refractive index of 1.53 materials must be used. For example, an ultraviolet curable resin having a double bond site such as an acrylic resin or an ene / thiol, and the double bond is cleaved by irradiation with ultraviolet light to promote polymerization, and the refractive index after curing is 1.53. Certain resins may be used.

The liquid crystal panel 2 thus joined together
… So that it covers almost all of the front and back surfaces of
The liquid crystal display device 1 is formed by arranging the polarizing plates 8.8 in directions in which their polarization axes are orthogonal to each other. Generally, a direct-view type liquid crystal display device includes a backlight such as a cold-cathode tube as described above, and a liquid crystal panel placed in front of the backlight allows light of the backlight to be emitted according to image information. The image information modulated and input to the liquid crystal panel can be recognized. In the liquid crystal display device 1 of the present embodiment, the polarizing plate 8 is installed on almost the entire surface of the liquid crystal display device 1 configured by joining a plurality of the liquid crystal panels 2 as described above. Are installed on the front and back of the liquid crystal display device 1 in a direction in which their polarization axes are orthogonal to each other. Therefore, light leakage from the connection between the liquid crystal panels 2 and 2 normally causes black in the crossed Nicols state of the polarizing plate. Therefore, the above-mentioned connection portion is hardly conspicuous.

FIG. 1 is an enlarged view of a connecting portion of the liquid crystal panels 2 of the liquid crystal display device of the present invention, and the end faces of the two liquid crystal panels 2 are connected via an adhesive 9. At the same time, the reinforcing substrate 3 and the liquid crystal panels 2 are similarly bonded via an adhesive 9. The adhesive 9 used for bonding the reinforcing substrate 3 and the liquid crystal panel 2 is an ultraviolet-curing adhesive, which is cured by irradiating the adhesive 9 in a flowing state with ultraviolet rays. Due to the shrinkage of 5% to 10% occurring at the time, tensile stress
Acts within. For example, if the edge 2a of the conventional example shown in FIG. 12 (a) has a shape that has been cut out, stress concentration occurs near the edge 2a, and as a result, a crack 9a occurs. . Crack 9
The light transmitted through the liquid crystal panel a is scattered, and even if the polarizing plate 8 is provided, the light that matches the polarization direction of the polarizing plate 8 leaks upward, thereby making the connection between the liquid crystal panels 2 stand out. This has been an obstacle in promoting the multi-panel display of the liquid crystal display device.

Therefore, an arc-shaped chamfered portion 2b is formed at the edge of the connection end face of the liquid crystal panels 2 used in the present embodiment, as shown in FIG. This alleviates the internal stress of the adhesive 9 over the entire area of the chamfered portion 2b, so that the occurrence of the crack 9a as shown in FIG. 12B can be prevented. In the present embodiment, the chamfered portion 2b has an arc shape, and the radius of the chamfered portion 2b is 0.3 mm. The arc-shaped chamfered portion 2b is formed by, for example, rotating a grindstone 18 having a curved portion and shaving the edge of the liquid crystal panel 2 as shown in FIG. In the above method, first, rough grinding is performed using a grindstone having a grain size of # 300 to # 500,
Further, if the grinding is performed in two stages such as finishing using a grindstone having a grain size of # 800 to # 1600, a chamfered portion 2b with less unevenness can be obtained. The radius of the arc-shaped chamfered portion 2b may be optimally set according to the thickness of the liquid crystal panel 2, the installation conditions of the liquid crystal display device 1, and the like, but the shape of the chamfered portion 2b is limited to an arc shape. Instead, it may be processed into another shape that avoids stress concentration.

As a result, it was possible to obtain a liquid crystal display device in which light scattering and the like did not occur and connection portions between liquid crystal panels were inconspicuous. [Embodiment 2] FIG. 5 shows another embodiment of the present invention.
This will be described below with reference to FIG. For convenience of explanation, members having the same functions as those shown in the drawings of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 5 is a layout view of the liquid crystal panels 2 when they are laminated on a reinforcing substrate 3 (not shown). As shown in FIG. It is divided along the dividing lines 17 near the end of the display area, and is pasted on the reinforcing substrate 3 so that the divided portions are joined together. As shown in FIG. 3B, the connection width D generated when the liquid crystal panels 2 are joined together is usually smaller than the line width a of the black matrix 5 required for one pixel. Are aligned. When the connection width D is black matrix 5
If the line width a is too large, the pixel pitch of the entire screen is disturbed at the connection portion of the liquid crystal panels 2.

Therefore, the division of the liquid crystal panel 2 requires high division position accuracy and division section finishing accuracy. If the dividing lines 17 of the liquid crystal panel 2 are distorted or if there are irregularities of several hundred μm in the divided section of the liquid crystal panel 2, a larger gap will be generated when the liquid crystal panels 2 are joined. However, in a general method of dividing the liquid crystal panel 2 by scribing, it is not possible to avoid a distortion of a sectional plane of about several hundred μm. A cutting method using a dicing device is suitable for obtaining high cutting position accuracy and cutting section finishing accuracy. If a dicing machine is used, even if the production speed during mass production is taken into consideration, the cutting position accuracy of the connection-side end face portion is 50 μm or less, and the cross-section finishing accuracy is 5 μm.
m or less. In addition, as shown in FIG. 6, what is referred to above as the dividing position accuracy is the maximum value A of the deviation of the actual dividing line from the designed dividing line, and is referred to as the dividing section finishing accuracy. What is
It is the maximum height B in the surface roughness of the end face shown in the enlarged circle in FIG.

As described above, since the connection width D is equal to or less than the line width a of the black matrix 5, the pixel pitch of the entire liquid crystal display device 1 can be made uniform.

However, when joining the end faces of the liquid crystal panel 2 using the adhesive 9 as described above, it is necessary to pay attention to the curing shrinkage of the adhesive 9. That is, due to the stress concentration of the internal stress caused by the curing shrinkage, the adhesive 9 at the edge 2a of the liquid crystal panel 2 as shown in FIG.
12a and the end face 2c as shown in FIG.
In this case, there is a possibility that a peeled portion 9b is generated between the adhesive 9 and the adhesive.

Therefore, the crack 9a and the peeled portion 9b
Think about how to prevent it. For example, since the internal stress is caused by the curing shrinkage of the adhesive 9, the absolute value of the volume shrinkage becomes smaller by reducing the volume of the adhesive 9 to be used. Thereby, the internal stress generated in the adhesive 9 at the time of curing shrinkage can be reduced. The above-mentioned cracks and peeling are caused by a large flexural modulus (hereinafter simply referred to as an elastic modulus) of the generally used adhesive 9 upon curing and contraction, that is, a high rigidity. Therefore, the effect of curing shrinkage can be offset by using the adhesive 9 having a small elastic modulus.

Based on the above idea, a plurality of test pieces 19 shown in FIG. 7 were prepared, and the appearance of cracks was observed. The test piece 19 includes a glass plate 20 (width 60 mm × depth 100 mm × thickness 2.8 mm) simulating a reinforcing substrate in a liquid crystal display device, and glass plates 21, 21 simulating a liquid crystal panel.
(Width 30mm x depth 100mm x thickness 2.2mm)
Is used, the thickness of the adhesive 22 is set in the same manner as in the actual liquid crystal display device, and the adhesive 22 is attached. And the glass plate 21
A test piece 19 having various patterns was prepared by combining the adhesive 22 with various changes in the connection width D between 21 and various resins having different elastic moduli, and observing the number of cracks generated at the edge portion. FIG. 8 shows the results.

As can be seen from the figure, the elastic modulus is 4000
It can be seen that when a resin having a weight of not more than kgf / cm ² is used as the adhesive 22, the number of cracks caused by the curing shrinkage of the adhesive 22 is significantly reduced regardless of the connection width D. From this result, when a resin having an elastic modulus of 4000 kgf / cm ² or less is used as the adhesive 22, the internal stress generated by the strain caused by the contraction and curing of the adhesive 22 is offset by the elasticity of the adhesive 22, and the liquid crystal panel It can be estimated that this is because the intermolecular attraction between the adhesive 2 and the adhesive 9 becomes smaller.

In the test piece 19, even if a resin having an elastic modulus larger than 4000 kgf / cm ² (resin of 6000 kgf / cm ² or more in the experiment) is used as the adhesive 22, the connection is made regardless of the type of the resin. It can be seen that when the width D is 50 μm or less, the number of cracks generated due to the curing shrinkage of the adhesive 22 is significantly reduced in the same manner as described above. That is, when the connection width D is set to 50 μm or less, the internal stress due to the reduction of the absolute shrinkage amount does not depend on the characteristics considered to be greatly related to the occurrence of cracks, such as the flexural modulus of the adhesive. Due to the reduction in the value, the maximum value of the stress becomes equal to or less than the intermolecular bonding force of the adhesive 22, and it can be estimated that the number of cracks generated near the edge portion is kept low. At the same time, in the test piece 19, the formation of the peeled portion 9b as shown in FIG. 12B of the conventional example was not observed at the interface between the adhesive 22 and the glass plates 21.

From the above results, in the liquid crystal display device 1 having the same configuration, the elastic modulus of the resin used for the adhesive 9 is set to 4000 kgf / cm ² or less, or the connection width between the liquid crystal panels 2 By setting D to 50 μm or less as described above, it is considered that cracks generated near the edge 2a and separation between the end face 2c and the adhesive 9 can be prevented. Further, when the connection width D between the liquid crystal panels 2 is set to 50 μm or less, as described above, cracks and peeling generated in the adhesive 9 filling the connection portion are reduced, and at the same time, the light in the adhesive layer is reduced. Since the influence of absorption and birefringence can be reduced, display performance is improved.

Actually, the position of the dividing line 17 is set,
As a result of producing a liquid crystal display device 1 using a resin having an elastic modulus of 10,000 kgf / cm ² as an adhesive 9 with a connection width D between the liquid crystal panels 2 and 50 μm, cracks and peeling at a connection portion were not observed. The liquid crystal display device 1 in which the connection between the liquid crystal panels 2 is less noticeable was obtained. Also,
In the result of producing the liquid crystal display device 1 having a connection width D = 100 μm using a resin having an elastic modulus of 2000 kgf / cm ² as the adhesive 9, no cracks or peeling at the edges were observed, and the liquid crystal panel 2 Can be obtained as the liquid crystal display device 1 in which the connection portion is less noticeable. [Embodiment 3] Another embodiment of the present invention will be described below with reference to FIGS. For convenience of explanation, members having the same functions as those shown in the drawings of the second embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the second embodiment, in order to prevent cracks due to shrinkage and curing of the adhesive 9 and peeling, the connection width D is 5
It has been stated that 0 μm or less is sufficient. However, since the refractive index of the adhesive used for connecting the liquid crystal panels 2 varies depending on the composition, curing conditions and environmental temperature, the refractive index at the time of curing becomes equal to that of the liquid crystal panel 2. It is practically difficult to manage the values on the order of 0.005, and a certain degree of variation occurs during mass production. 9 (a) and 9 (b), it can be seen that when the connection width between the liquid crystal panels 2 and 2 is large, not only does the distortion of the image observed through the adhesive 9 increase, but also the color Will also change. Therefore, FIG.
As shown in (b), the smaller the connection width D, the smaller the image distortion due to the influence of light absorption and birefringence in the adhesive layer, and the display performance can be improved.

However, in the above-mentioned dicing apparatus, if the work feed speed is reduced between the mesh of the blade to be divided, the number of rotations, and the work feed speed, the processing accuracy is improved, but the processing capacity is greatly increased. On the other hand, if the blade mesh is made finer and rotated at high speed, the accuracy of the cross section finish improves, but the blur of the blade increases,
There is a trade-off relationship that the cutting position accuracy is reduced. When mass production is assumed, it is difficult to make the cutting position accuracy smaller than 50 μm or less while maintaining the cross section finishing accuracy of 5 μm or less.

Therefore, a step of polishing the connection side end face 2c of the liquid crystal panel 2 with a grindstone is provided. As a result, the liquid crystal panel 2.
The connection width D between the two can be further reduced. After being cut by the dicing apparatus described above, the end face of the liquid crystal panel 2 was polished to obtain a liquid crystal panel 2 having a cut position accuracy of 10 μm or less. By using the liquid crystal panel 2, the connection width between the liquid crystal panels 2 is reduced to 2
0 μm or less could be achieved.

Using the above polishing step, a plurality of liquid crystal panels 21 'having different cutting position accuracy are prepared, and a test piece 1 as shown in FIG.
A plurality of 9's were manufactured, and the visibility was evaluated based on the difference in the connection width D. The test piece 19 ′ is formed on the reinforcing substrate 20 ′ (width 580 mm × depth 440 mm × thickness) using the adhesive 22.
2.8mm) and the liquid crystal panel 21 '
-21 '(290 mm wide x 440 mm deep x 2.2 mm thick) bonded together.

[0041]

[Table 1]

As a result, when the connection width D is 20 μm or less,
It was possible to obtain a liquid crystal display device with good visibility, which was hardly affected by variations in the refractive index of the adhesive. That is,
If a liquid crystal panel with a division position accuracy of 10 μm or less is used,
Since the connection width D is always 20 μm or less, good visibility can always be obtained. [Embodiment 4] FIG. 1 shows another embodiment of the present invention.
0 will be described below. For convenience of explanation, members having the same functions as those shown in the drawings of the second embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As described above, in the division by the dicing device, when the liquid crystal panels 2 are connected by the adhesive 9, the adhesive 9 does not sufficiently penetrate to every corner of the unevenness of the divided section, and the liquid crystal panel Small bubbles remain between the end face 2c of the second member 2 and the adhesive 9, and light may be scattered by the bubbles. This is presumably because the cross-section finishing accuracy of about 5 μm obtained by the dicing apparatus described above does not provide sufficient wettability between the adhesive 9 and the end face 2c.

Therefore, the liquid crystal panel 21 'having a different cross-sectional finish precision is obtained by using a polishing step using a grindstone as described above.
Were prepared. Then, a plurality of test pieces 19 ′ having the same shape as that shown in FIG. 10 were prepared, the connection portion was observed, and the entrapment of air bubbles was evaluated. However, in the test piece 19 'used in the present embodiment, the connection width D between the liquid crystal panels 21' and 21 'is set to 100 [mu] m in order to facilitate the observation of bubbles.

[0045]

[Table 2]

From the above results, it can be seen that the sectional finish accuracy is 2 μm.
At m or less, it was found that air entrainment was not observed. Thereby, scattering of light due to bubbles at the connection portion was prevented, and a natural image was obtained.

The polishing of the end faces on the connection side of the glass plate 21 and the liquid crystal panel 21 'performed in the second to fourth embodiments is performed, for example, as shown in the processing example of the liquid crystal panel 2 in FIG. What is necessary is just to grind 2c with the rotating grindstone 23, etc. As the above-mentioned grindstone 23, a grindstone of # 800 is used, and a polishing speed 1 at a contact portion between the grindstone 23 and the end face 2c is set.
Polishing was performed under the conditions of km / min and a grinding wheel feed amount of 2 μm / step. As a result, it was possible to obtain an end face portion 2c having a division position accuracy of 10 μm or less and a division finish surface accuracy of 2 μm or less. When the surface of the end face portion 2c before polishing is rough, first, rough grinding is performed using a grindstone having a grain size of # 300 to # 500, and then finishing is performed using a grindstone having a grain size of # 800 to # 1600. As described above, by performing the two-stage polishing, the end face portion 2c with less unevenness can be obtained.

In each of the above embodiments, a multi-panel type liquid crystal display device in which a liquid crystal panel is connected to increase the screen size is shown. However, this method of increasing the screen size is not applied to only the liquid crystal panel. For example, a plasma display or EL (Electro Lumines)
cent) It may be applied to a multi-panel display using a display or the like.

[0049]

According to the present invention, since the adhesive filling the connection portion of the display panel does not crack or peel off, the connection portion of the liquid crystal panel is inconspicuous and a large-screen display device excellent in visibility can be obtained. It has the effect of being able to do so. Further, by combining the above configurations, further improvement of the above effects can be expected.

Further, the wettability of the connection-side end surface is improved, and the connection between the display panels can be performed without bubbles remaining at the interface with the adhesive. Therefore, light scattering due to the bubbles does not occur. There is an effect that a large-screen display device with excellent visibility in which connection portions of the display panel are inconspicuous can be obtained.

Further, since the connection width between the display panels can be set to 20 μm or less, even if the refractive index of the adhesive varies, the color is hardly affected and the display panel connection portion is not affected. This suppresses distortion of an image passing through the display device and makes it possible to provide a large-screen display device in which the connection portion is inconspicuous and has excellent visibility.

[Brief description of the drawings]

FIG. 1 is a cross-sectional perspective view showing a connection portion between liquid crystal panels of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of a liquid crystal display device according to an embodiment of the present invention.

FIG. 3 is a perspective view showing a configuration pattern of a liquid crystal panel provided in the liquid crystal display device.

FIG. 4 is a diagram illustrating an example of a method of forming a chamfer of a liquid crystal panel.

FIG. 5 is a view showing an arrangement of a liquid crystal panel, and FIG.
FIG. 4 is a plan view showing a cutting position at a connection portion between a single liquid crystal panel and a liquid crystal panel, and FIG. 4B is a plan view showing an arrangement of the liquid crystal panel after cutting.

FIG. 6 is a perspective view of a liquid crystal panel for explaining division position accuracy and division section finishing accuracy.

FIG. 7 is a perspective view showing a shape of a test piece according to another embodiment of the present invention.

FIG. 8 is a graph showing the results of measuring the number of cracks generated at the edge portion using a plurality of adhesives having different flexural modulus after curing, and the horizontal axis represents the connection width D between test pieces. The vertical axis indicates the rate of occurrence of a non-dimensional crack based on the maximum number of cracks.

FIG. 9 is an explanatory diagram showing a degree of deformation due to a difference in a connection width of an image transmitted through a connection portion.

FIG. 10 is a perspective view showing a shape of a test piece according to another embodiment of the present invention.

FIG. 11 is a schematic view showing a method of processing an end face of a liquid crystal panel.

FIG. 12 is a cross-sectional perspective view showing a connection portion between liquid crystal panels of a liquid crystal display device using a conventional multi-panel display method.

[Explanation of symbols]

 Reference Signs List 1 liquid crystal display device (display device) 2 liquid crystal panel (display panel) 2a edge (edge portion) 2b chamfered portion 2c end surface portion (connection end surface) 9 adhesive D connection width (interval)

Claims (3)

[Claims] 1. A multi-panel display device that performs a large-screen display by connecting a plurality of display panels each formed of a pair of substrates whose periphery is sealed, to end faces of the display panels adjacent to each other. The display device is characterized in that adjacent connections are made using an adhesive that undergoes volume shrinkage at the time of curing, and the end precision at the end of the connection side of the display panel is 2 μm or less. 2. A multi-panel display device which performs a large-screen display by connecting a plurality of display panels each formed of a pair of substrates whose periphery is sealed, to adjacent end faces of the display panels. Are connected adjacently using an adhesive with volume shrinkage at the time of curing, and the connection-side end face of the display panel has a cutting accuracy of 10 μm.
A display device characterized by the following. 3. A multi-panel display device which performs a large-screen display by connecting a plurality of display panels each formed of a pair of substrates whose peripheral edges are sealed to each other so that their display end faces are adjacent to each other. Is 50 μm or less.