JP2010054552A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which includes a plurality of columnar spacers which are different in height, improves strength against force on the face, restrains occurrence of vacuum bubbles, and is easy to manufacture even if a difference in height between two columnar spacers is small. <P>SOLUTION: The liquid crystal display device 10A includes: a first substrate 12 and a second substrate 13 which are arranged facing each other across a liquid crystal layer 11; a CF (color filter) layer-formed area, in which a CF layer 32 is formed, and a CF layer-unformed area in which the CF layer 32 is not formed, these areas being provided in the second substrate 13; a transparent resin layer 34 which is formed to extend over the CF layer-formed area and the CF layer-unformed area; a first spacer 14A which is arranged in the CF layer-formed area and contacts the first and second substrates 12 and 13; and a second spacer 14B which is arranged in the CF layer-unformed area and contacts only either the first substrate 12 or the second substrate 13. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a liquid crystal display device having columnar spacers that maintain the thickness of a liquid crystal layer. Specifically, the present invention relates to a liquid crystal display device including a plurality of first spacers that are in contact with both the array substrate and the color filter substrate and a plurality of second spacers that are in contact with only one of the array substrate and the color filter substrate.

A liquid crystal display device is characterized by being lighter, thinner, and lower in power consumption than a CRT (cathode ray tube), and is used in many electronic devices. The liquid crystal display device displays an image by changing the direction of liquid crystal molecules of a liquid crystal layer sandwiched between an array substrate and a color filter substrate by an electric field, and changing the amount of transmitted light. In order to make the liquid crystal layer thickness (cell gap) constant,
Transparent spherical particles (beads) such as glass, silica, or synthetic resin, which are called spherical spacers, are dispersed in the display area. Since these spherical spacers are transparent particles, there is a problem in that light is leaked through the spherical spacers during black display when the spherical spacers are present together with the liquid crystal in the display pixels. Further, since the spherical spacer exists between the array substrate and the color filter substrate, the alignment of the liquid crystal molecules in the vicinity of the spherical spacer is disturbed, and there is a problem that light leakage occurs in this portion and the contrast is lowered.

In order to solve these problems, columnar spacers (photo spacers) have been formed on either the array substrate or the color filter substrate. In recent years, there has been an increasing demand for increasing the strength of liquid crystal display devices. Accordingly, there is a demand for a design that restores the original cell gap in a short time after pressing the panel of the liquid crystal display device and suppresses the occurrence of color unevenness and domains.

In liquid crystal display devices that use columnar spacers to maintain the cell gap, the columnar spacer design (arrangement, area density, spacer compression characteristics, etc.) has a significant effect on the cell gap between the array substrate and the counter substrate, the surface pressing strength of the cells, etc. give. In order to increase the surface pressing strength of the liquid crystal display device, it is effective to increase the area density of the columnar spacers (the area ratio of the columnar spacers to the panel area). However, when this method is used, there is a problem that vacuum bubbles are easily generated.
For example, under a low temperature environment such as −20 ° C., all members constituting the liquid crystal display device are in a state of being contracted. Since the contraction rate of the liquid crystal is the largest among the members constituting the liquid crystal display device, the liquid crystal display device is contracted in the direction of reducing the cell gap. At this time, if the density of the columnar spacers is too high for the amount of change in which the cell gap is contracted due to external impact force, negative pressure is generated inside the liquid crystal layer if the columnar spacers cannot follow the deformation. As a result, vacuum bubbles (low temperature bubbles) are generated inside the liquid crystal layer.

As a method for solving such a problem, as disclosed in the following Patent Document 1, by increasing the amount of surface pressing strength and vacuum bubbles by mixing columnar spacers having different heights and cross-sectional areas in a liquid crystal display panel, The technology of making the generation | occurrence | production suppression compatible is known. The technique of mixing columnar spacers having different heights is a solution for making the cell gap into two stages. That is, the first columnar spacer having a height necessary for maintaining the first cell gap when no external force in the vertical direction is applied to the liquid crystal display panel, and the first cell when the external force is applied. This is a structure having a second cell gap for preventing the columnar spacers holding the gap from being crooked by exceeding the shrinkable amount. At this time, until the first columnar spacer is pushed to the second cell gap by an external force, only the first columnar spacer holding the first cell gap has to follow the change in the cell gap.
Compared to a case where the number of columnar spacers that simply hold the first cell gap is increased, a margin for the generation of vacuum bubbles can be widened. In addition, when the external force is removed, the original state is easily restored, and there is an advantage that the pressure resistance increases when the second columnar spacer starts to deform.
Japanese Patent No. 3925142

However, due to the recent progress of high definition, the demand for high response speed of the liquid crystal display device, and the demand for improvement of the display image quality of the liquid crystal display device, it is required to make the cell gap smaller. However, when the cell gap is reduced, the columnar spacer is shortened, so that the amount of deformation up to the limit of elasticity is reduced. For this reason, in the case of the liquid crystal display device including the first spacer and the second spacer as described above, the allowable size of the gap until the second columnar spacer starts to be deformed has become small, and thus is difficult to manufacture. There was a problem.

On the other hand, in the color filter substrate, a light shielding member (black matrix) and a color filter layer are formed on the surface of the transparent substrate, and the color filter layer is also formed on the surface of the light shielding member. In addition, the height (thickness) from the surface of the transparent substrate is substantially the same for the color filter layer portion and only the color filter layer portion on the light shielding member due to the leveling property of the color filter layer forming material. Therefore, if the color filter layer on the surface of the light shielding member is removed, a difference in height from the surface of the transparent substrate can be formed accordingly, so this difference in height is temporarily different between the first columnar spacer and the second columnar spacer. It can be used as a difference in height from the surface of the transparent substrate.

However, since the control of the height of the columnar spacers by such a method completely depends on the film thickness of the color filter layer, it is difficult to set the first columnar spacers and the second columnar spacers to a desired height. That is, since the resist which is a normal color filter layer forming material is a negative resist, it is difficult to control the film thickness by the exposure amount. Moreover, in order to make a difference in film thickness by exposure amount, it is necessary to expose the resist with a different exposure amount, so it is necessary to increase the number of shots with a photomask or use a multi-tone mask, so that the manufacturing process Becomes complicated. In addition, at the present time when higher color rendering of the color filter layer is required, the step formed by the color filter layer forming material becomes too large as the color filter layer becomes thicker.

The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a surface push for a liquid crystal display device including a first columnar spacer and a second columnar spacer. It is possible to achieve the effect of improving the strength and the effect of suppressing the vacuum bubbles, and easily manufacture even when the allowable dimension of the gap until the second columnar spacer starts to deform is about 0.1 μm to 0.3 μm. It is an object of the present invention to provide a liquid crystal display device capable of performing

In order to achieve the above object, a liquid crystal display device according to the present invention includes a first substrate and a second substrate that are disposed to face each other with a liquid crystal layer interposed therebetween, and a color filter layer provided on the second substrate. A color filter layer forming region and a color filter layer non-forming region in which the color filter layer is not formed, a transparent resin layer formed over the color filter layer forming region and the color filter layer non-forming region, and the color A first spacer disposed in the filter layer formation region and in contact with both the first substrate and the second substrate, and a second spacer disposed in the color filter layer non-formation region and in contact with only one of the first substrate and the second substrate. It is characterized by comprising.

The second substrate of the liquid crystal display device of the present invention includes a color filter layer forming region where the color filter layer is formed and a color filter layer non-forming region where the color filter layer is not formed. Moreover, both the color filter layer forming region and the color filter layer non-forming region are covered with a transparent resin layer. This transparent resin layer is formed by applying and curing a transparent resin forming material on the color filter layer forming region and the color filter layer non-forming region. At this time, since the transparent resin forming material is leveled before curing, the thickness of the transparent resin layer in the color filter layer non-forming region is larger than the thickness of the transparent resin layer in the color filter layer forming region.

With this configuration, the first spacer is in contact with both the first substrate and the second substrate due to the presence of the color filter layer, and the second spacer is one of the first substrate or the second substrate due to the absence of the color filter layer. To touch. Therefore, when a pressing force is applied to the outer surface of one of the substrates, first, the first spacer in contact with both the substrates is elastically deformed and compressed, and the distance between the substrates gradually decreases. Then, when there is no gap between the second spacer that has been in contact with only one of the substrates and the substrate and the substrates are in contact with each other, the first and second spacers allow the substrates to be placed on the liquid crystal layer side of both substrates. A reaction force against the pressing force on the outer surface of the plate acts. That is, a reaction force is generated only by the first spacers in contact with both substrates in the initial state for an external force smaller than a predetermined value, and only one substrate in the initial state for an external force exceeding a predetermined value. Second in contact
A reaction force can also be generated supplementarily by the spacer. In addition, since the substrate distance between the color filter layer forming region and the color filter layer non-forming region is adjusted by providing the transparent resin layer, the height of the first spacer that contacts both substrates and the first substrate that contacts only one substrate are adjusted. 2
There is no need to make the spacer height different. Therefore, the manufacture of the columnar spacer can be facilitated.

In addition, in the liquid crystal display device of the present invention, the difference between the thickness of the transparent resin layer in the color filter layer forming region and the thickness of the transparent resin layer in the color filter layer non-forming region is as small as about 0.1 μm to 0.3 μm. It can be controlled to achieve a desired value within a range. Therefore, in the liquid crystal display device of the present invention, when the first spacer in the color filter layer forming region is in contact with both the first substrate and the second substrate, the color filter layer of the first substrate or the second substrate is not. The distance between the second spacer disposed in the formation region and the other substrate can be easily accommodated within the allowable dimensional difference. Therefore, according to the liquid crystal display device of the present invention, the effect of improving the surface pressing strength of the liquid crystal display device and the effect of suppressing the vacuum bubbles can be achieved, and further, the margin of liquid crystal dripping is improved when the substrate is sealed by the ODF method. The effect to make also arise.

In the liquid crystal display device of the present invention, it is preferable that the first spacer and the second spacer are formed on the second substrate.

According to the liquid crystal display device of the present invention, since the second columnar spacer can be formed in a state where it is accurately aligned with the position of the color filter layer non-formation region of the second substrate, the array substrate and the color filter substrate are attached. An accurate distance between the substrates can be secured even when they are combined.

In the liquid crystal display device of the present invention, it is preferable that the first spacer and the second spacer have the same height.

According to the liquid crystal display device of the present invention, by making the heights of the first spacer and the second spacer the same, when the cell gap is smaller than the conventional case, compared to the case of forming columnar spacers having different heights. Thus, the manufacture of the columnar spacer can be facilitated.

In the liquid crystal display device of the present invention, the second substrate includes light shielding means for partitioning a plurality of pixels, and at least one of the first and second spacers is flat with the light shielding means for partitioning the plurality of pixels. It is preferable that they overlap visually.

Furthermore, in the liquid crystal display device of the present invention, the second substrate includes a light shielding unit that overlaps with a switching element provided on the first substrate in a plan view, and at least one of the first and second spacers is the It is preferable that it overlaps with the light shielding means which overlaps with the switching element in plan view.

The second substrate is formed with a light shielding means for normally partitioning a plurality of pixels and a light shielding means for shielding the portion formed on the first substrate. According to the liquid crystal display device of the present invention, it is possible to prevent the aperture ratio from being lowered by the first and second spacers by using such an existing light shielding means.

Hereinafter, the best embodiment of the present invention will be described with reference to the drawings. However, the embodiment described below describes an example of a liquid crystal display device for embodying the technical idea of the present invention,
The invention is not intended to be specific to this liquid crystal display device, but is equally applicable to other embodiments within the scope of the claims. In each drawing used for the description in this specification, each layer and each member are displayed in different scales so that each layer and each member can be recognized on the drawing. However, it is not necessarily displayed in proportion to the actual dimensions.

FIG. 1 is a schematic plan view showing an array substrate of sub-pixels of the liquid crystal display device according to the embodiment.
2 is a cross-sectional view taken along line II-II in FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view of a portion corresponding to FIG. 2 of the comparative example.

As shown in FIGS. 2 and 3, in the liquid crystal display device 10 according to the embodiment, the liquid crystal layer 11 is sandwiched between the array substrate 12 and the color filter substrate 13. The thickness of the liquid crystal layer 11 is made uniform by the first spacer 14A (see FIG. 2). A first polarizing plate 15 is formed on the back surface of the array substrate 12, and a second polarizing plate 16 is formed on the front surface of the color filter substrate 13. Light is irradiated from the back side of the array substrate 12 by the backlight 17.

First, the configuration of the array substrate 12 will be described. The array substrate 12 has a first substrate body 18 made of a transparent substrate such as glass, quartz, or plastic. A scanning line 19 is formed on the first substrate body 18. A first insulating film (gate insulating film) 20 made of silicon nitride, silicon oxide or the like is formed so as to cover the scanning line 19. A semiconductor layer 21 made of, for example, amorphous silicon is formed on the first insulating film 20, and a source electrode S and a drain electrode D are formed so as to partially run over the semiconductor layer 21. The semiconductor layer 21 is arranged to face the branch portion of the scanning line 19 with the first insulating film 20 interposed therebetween, and the branch portion of the scanning line 19 constitutes the gate electrode G of the TFT. These semiconductor layer 21, source electrode S, drain electrode D and gate electrode G constitute a TFT. The source electrode S branches from the signal line 22. Further, a second insulating film (passivation film) 23 made of silicon nitride or silicon oxide is formed so as to cover the signal line 22 and the drain electrode D.

An interlayer film 24 is formed so as to cover the second insulating film 23, and a lower electrode 25 made of a transparent conductive material is formed so as to cover the interlayer film 24. A contact hole 26 that reaches the drain electrode D through the interlayer film 24 and the second insulating film 23 is formed, and the lower electrode 25 and the drain electrode D are electrically connected through the contact hole 26. . Therefore, the lower electrode 25 operates as a pixel electrode.

A third insulating film 27 made of silicon nitride or silicon oxide is formed so as to cover the lower electrode 25. An upper electrode 28 made of a transparent conductive material is formed on the surface of the third insulating film 27.
An alignment film (not shown) made of polyimide, for example, is formed so as to cover the third insulating film 27 and the upper electrode 28. This alignment film is rubbed in the scanning line 19 direction. The direction of this rubbing process is the X-axis direction in FIG. The upper electrode 28 is formed over all the sub-pixels, and is electrically connected to the common wiring at the peripheral edge of the liquid crystal display device 10. Therefore, the upper electrode 28 operates as a common electrode. Further, the upper electrode 28 includes a strip-shaped electrode portion 30 formed by a plurality of slits 29 for each subpixel. The slit 29 has, for example, an oval shape with a width of about 4 μm and a length of about 50 μm. The slit 29 has a region inclined by 5 ° clockwise with respect to the X-axis direction and a region inclined by 5 ° counterclockwise. There are two areas.

The upper electrode 28 is formed across all sub-pixels, and includes a strip-shaped electrode portion 30 formed by a plurality of slits 29. Two types of slits 29 are formed, for example, inclined 5 degrees clockwise and 5 degrees counterclockwise with respect to the X-axis direction. That is, it is multi-domain and reduces the phenomenon that the color changes depending on the viewing angle direction because the liquid crystal molecules are twisted in one direction. The slit 29 is formed by exposing and etching the upper electrode 28.

Next, the color filter substrate 13 will be described. The color filter substrate 13 includes a second substrate body 31 made of a transparent insulating material such as glass, quartz, or plastic. The second substrate body 31 has different colors of light (for example, A CF (color filter) layer 32 that transmits R, G, B, or colorless) and a light shielding material BM (light shielding member) 33 are formed. The BM 33 is formed in a region overlapping the scanning line 19, the signal line 22, and the TFT in plan view. Further, the CF layer 32 is formed at a location where the first spacer 14A is formed,
It is not formed at the place where the second spacer 14B is formed. Both the CF layer formation region and the CF layer non-formation region are covered with the transparent resin layer 34.

The liquid crystal display device 10 includes a plurality of first spacers 14A for keeping the thickness of the liquid crystal layer 11 constant.
And a plurality of second spacers 14B having a predetermined area density. As shown in FIG.
The spacer 14 </ b> A is formed on the surface of the transparent resin layer 34 in the region where the CF layer 32 exists on the surface of the BM 33 and is in contact with the array substrate 12. In contrast, the second spacer 14
B is formed on the surface of the transparent resin layer 34 in the CF layer non-covering region on the surface of the BM 33 and is separated from the array substrate 12. The height L1 of the first spacer 14A and the height L2 of the second spacer 14B are the same. Therefore, the transparent resin layer 3 on which the first spacer 14A is formed.
4 and the step L3 between the surface of the transparent resin layer 34 on which the second spacer 14B is formed and the gap L4 between the second spacer 14B and the array substrate 12 are the same.

Thus, the reason why the thickness of the transparent resin layer 34 is different between the CF layer forming region and the CF layer non-covering region is as follows. The transparent resin layer 34 is formed by applying and curing a transparent resin forming material on the CF layer forming region and the CF layer non-forming region. At that time, since the transparent resin forming material is leveled before curing, the thickness of the transparent resin layer 34 in the CF layer non-forming region is larger than the thickness of the transparent resin layer 34 in the CF layer forming region. Therefore, the difference L3 (= L4) between the thickness of the transparent resin layer 34 in the CF layer formation region and the thickness of the transparent resin layer 34 in the CF layer non-formation region is a desired value within a small range of about 0.1 μm to 0.3 μm. It becomes possible to control to become.

As described above, the liquid crystal display device 10 is in contact with both the array substrate 12 and the color filter substrate 13 and the plurality of first spacers 14A and the color filter substrate 13, but the array substrate 12 is L4. A plurality of second spacers 14B having gaps are provided. Since the deformation of the first spacer 14A easily follows the external force until the first spacer 14A is elastically deformed by the external force and the second spacer 14B comes into contact with the array substrate 12, the bubbles at the time of low temperature impact Is less likely to occur. Further, since the second spacer 14B is not deformed until the second spacer 14B comes into contact with the array substrate 12, the contact area of the first spacer 14A is small when an external force in a direction in which the surface of the color filter substrate 13 is shifted is applied. , The deformation easily returns to the original state. When there is an external force greater in the vertical direction than that, the second spacer 1
Since 4B is also deformed, the pressure resistance value until the first spacer 14A exceeds the elastic limit and becomes plastically deformed can be improved.

In recent years, it has been required to reduce the cell gap due to the demand for improving the display characteristics of the liquid crystal display device, such as the response speed of the liquid crystal display device. For example, the height L1 of the first spacer 14A
Is required to be reduced from 6 μm to 3 μm, for example, in order to prevent plastic deformation of the first spacer 14A, the gap L4 between the second spacer 14B and the array substrate 12 is set to 0. 0, for example.
It will have to be reduced from 4 μm to 0.2 μm. In this case, since the height L1 of the first spacer 14A and the height L2 of the second spacer 14B are the same, the surface of the transparent resin layer 34 on which the first spacer 14A is formed and the second spacer 14B are formed. The transparent resin layer 34 may be formed so that the step L3 on the surface of the transparent resin layer 34 is 0.2 μm.

If the transparent resin layer 34 is not formed as shown in FIG. 4 which is a cross-sectional view corresponding to FIG. 2 of the liquid crystal display device 50 of the comparative example, the step L5 between the BM 33 and the CF layer 32 is 0.2 μm. It is difficult to make. The liquid crystal display device 50 of the comparative example shown in FIG. 4 is different from the liquid crystal display device 10 of the embodiment shown in FIG. 2 only in that the transparent resin layer is not formed. The same components as those shown are denoted by the same reference numerals, and detailed description thereof is omitted. That is, the step L5 between the BM 33 and the CF layer 32 of a general liquid crystal display device is 0.
Since the resist for the color material for forming the CF layer is a negative resist, it is difficult to control the film thickness by the exposure amount. Therefore, in the liquid crystal display device of the present invention, it is possible to easily control a minute film thickness of about 0.2 μm by forming the transparent resin layer 34 as described above.

If the height L1 of the first spacer 14A and the height L2 of the second spacer 14B are the same, both can be manufactured simultaneously by the photolithography method, so that the first and second spacers can be easily manufactured. Further, since the first spacer 14A and the second spacer 14B are formed on the color filter substrate 13, when the first substrate and the second substrate are bonded together, the second spacer does not deviate from a predetermined position. Positioning becomes easy.

Although not shown, an alignment film made of polyimide, for example, is formed so as to cover the transparent resin layer 34. This alignment film is rubbed in the X-axis direction opposite to the rubbing process direction of the alignment film of the array substrate 12. In the initial state, the liquid crystal molecules aligned in parallel along the rubbing direction are rotated in the direction of the electric field by applying a voltage between the upper electrode 28 and the lower electrode 25. Based on the difference between the initial alignment state and the alignment state at the time of voltage application, the light and dark display of each sub-pixel is performed. Although not shown, the liquid crystal layer 11 is sealed in a sealed area formed of a sealing material provided between the array substrate 12 and the color filter substrate 13.
In the liquid crystal display device 10 of the above embodiment, the first spacer 14A and the second spacer 14
In the example, B is formed on the color filter substrate 13. However, at least the first spacer may be formed on the array substrate 12, and both may be formed on the array substrate 12.

Further, although the liquid crystal display device 10 of the above embodiment is an example of an FFS mode liquid crystal display device, the present invention is not limited to this, and a horizontal electric field type liquid crystal display device such as an IPS (In-Plane Switching) mode is used. , TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, M
OCB with excellent VA (Multi-domain Vertical Alignment) mode and high-speed response
The present invention is applicable to a vertical electric field type liquid crystal display device such as an (Optically Compensated Bend) mode.

It is a schematic plan view which shows the array substrate of the sub pixel of the liquid crystal display device which concerns on embodiment. It is sectional drawing of the II-II line of FIG. It is sectional drawing of the III-III line | wire of FIG. It is sectional drawing of the part corresponding to FIG. 2 of a comparative example.

10: Liquid crystal display device 11: Liquid crystal layer 12: Array substrate 13: Color filter substrate
14A: 1st spacer 14B: 2nd spacer 15: 1st polarizing plate 16: 2nd polarizing plate
17: Backlight 18: First substrate body 19: Scanning line 20: First insulating film 21: Semiconductor layer 22: Signal line (source line) 23: Second insulating film (passivation film) 24:
Interlayer film 25: Lower electrode 26: Contact hole 27: Third insulating film 28: Upper electrode 2
9: Slit 30: Strip electrode part 31: Second substrate body 32: Color filter (CF
) Layer 33: Black matrix 34: Transparent resin layer

Claims (5)

A first substrate and a second substrate disposed opposite to each other with a liquid crystal layer interposed therebetween; a color filter layer forming region in which a color filter layer provided on the second substrate is formed; and a color in which the color filter layer is not formed A transparent resin layer formed so as to cover the color filter formation region and the color filter non-formation region across the filter layer non-formation region, and the color filter layer formation region and the color filter layer non-formation region; A first spacer disposed in the color filter layer formation region and in contact with both the first substrate and the second substrate, and a first spacer disposed in the color filter layer non-formation region and in contact with only one of the first substrate and the second substrate. A liquid crystal display device comprising two spacers. The first and second spacers are formed on the second substrate.
A liquid crystal display device according to 1. The liquid crystal display device according to claim 1, wherein the first spacer and the second spacer have the same height. The second substrate includes a light shielding unit that partitions a plurality of pixels, and at least one of the first and second spacers overlaps the light shielding unit that partitions the plurality of pixels in a plan view. Item 4. The liquid crystal display device according to any one of items 1 to 3 The second substrate includes a light shielding unit that overlaps the switching element provided on the first substrate in a plan view, and at least one of the first and second spacers overlaps the switching element in a plan view. The liquid crystal display device according to claim 1, wherein the liquid crystal display device overlaps visually.

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