The present application claims the benefit of Chinese Patent Application No. 201410644400.6, filed Nov. 14, 2014, the entire disclosure of which is incorporated herein by reference.
The present disclosure relates to the field of liquid crystal display technology, and particularly to a liquid crystal cell and a method for fabricating the same, a liquid crystal display panel, and a display device.
In the existing liquid crystal display technology, liquid crystal is generally injected between glass substrates to form a liquid crystal display panel. With the increase or decrease of environment temperature, the glass substrates and the liquid crystal may expand or shrink. The liquid crystal has a thermal expansion coefficient which is much larger than other components in a liquid crystal cell like glass substrates, and this will introduce problems. In one aspect, at high temperature, the liquid crystal in the liquid crystal display panel thermally expands to an extent significantly larger than other components, a thickness of the liquid crystal cell is increased, and the spacers cannot thermally expand to the same extent. In this case, liquid crystal in the liquid crystal display panel which is oriented vertically tends to move downward due to gravity. This is so-called gravity mura at high temperature. In another aspect, when the liquid crystal display panel is at low temperature, the liquid crystal thermally shrinks to an extent greater than other components. Namely, in case the thickness of the liquid crystal cell is kept constant, the liquid crystal will not fully fill the liquid crystal cell and thus vacuum bubbles will appear. This is so-called bubbles at low temperature. These defects restrict the application conditions of the liquid crystal display device, affect the display effect of the liquid crystal display device, and thus impair user experience. During the fabricating process, the allowable controlling range for amount of liquid crystal in case of defects of gravity mura at high temperature and bubbles at low temperature is referred to as LC Margin.
There is a need in the art for improving the liquid crystal display panel in terms of defects of gravity mura at high temperature and bubbles at low temperature.
The present disclosure aims to alleviate or solve the problems as mentioned above.
According to the present disclosure, by means of providing a volume variation compensating component in an active area of a liquid crystal cell, wherein the volume variation compensating component comprises a material with a thermal expansion coefficient opposite to that of the liquid crystal, so as to compensate variation in the volume of liquid crystal when temperature varies, the defects of gravity mura at high temperature and bubbles at low temperature are eliminated.
According to a first aspect of the present disclosure, there is provided a liquid crystal cell, comprising an active area and a dummy area, and comprising a first and second substrate which are arranged oppositely and separated by spacers, and liquid crystal arranged between the first and second substrate, wherein the liquid crystal cell further comprises a volume variation compensating component which is arranged in the active area, and the volume variation compensating component comprises a material with a thermal expansion coefficient opposite to that of the liquid crystal, so as to compensate variation in the volume of liquid crystal when temperature varies.
According to the present disclosure, the liquid crystal cell comprises a volume variation compensating component which is arranged in the active area, and the volume variation compensating component comprises a material with a thermal expansion coefficient opposite to that of the liquid crystal, so as to compensate variation in the volume of liquid crystal when temperature varies. In this way, not only defects of gravity mura at high temperature and bubbles at low temperature are eliminated to spread LC Margin, but also the scope of application environment (e.g. the range of operational temperature) for the liquid crystal display panel is expanded.
It is understood that, the expression of “one material has a thermal expansion coefficient opposite to that of another material” only refers to that the thermal expansion coefficients of these materials are opposite in sign, i.e., one of them has a positive thermal expansion coefficient while the other has a negative thermal expansion coefficient. It is further understood that a material with a positive thermal expansion coefficient refers to a material which expands with an increase in temperature and shrinks with a decrease in temperature, while a material with a negative thermal expansion coefficient refers to a material which expands with a decrease in temperature and shrinks with an increase in temperature. It is further understood that the expression “to compensate variation in the volume of liquid crystal when temperature varies” means to cancel out partially, and optionally cancel out completely variation in the volume of liquid crystal when temperature varies.
According to the present disclosure, the volume variation compensating component can be fillers which are uniformly dispersed within the liquid crystal.
According to the present disclosure, the fillers can be nanospheres, nanowires, or nanotubes.
According to the present disclosure, the spacers can be ball spacers.
According to the present disclosure, the spacers can be post spacers.
According to the present disclosure, the spacers can comprise main spacers and sub-spacers with a height smaller than that of the main spacers, and the volume variation compensating component can form the sub-spacers.
According to the present disclosure, the volume variation compensating component can be further arranged in the dummy area to form a buffer belt.
According to the present disclosure, the buffer belt can be arranged on the first substrate and/or the second substrate.
According to the present disclosure, the volume variation compensating component can comprise a material with a negative thermal expansion coefficient.
It is understood that the wording “comprise” is open-ended. For example, a volume variation compensating component comprising a material with a negative thermal expansion coefficient can not only relate to a volume variation compensating component which is completely made from a material with a negative thermal expansion coefficient, but also to a volume variation compensating component which includes a material apart from the material with a negative thermal expansion coefficient.
According to the present disclosure, the material with a negative thermal expansion coefficient can have an isotropic thermal expansion coefficient.
According to the present disclosure, the material with a negative thermal expansion coefficient can be selected from the group consisting of ZrW2O8, HfW2O8, ZrV2O7, and ThP2O7.
According to the present disclosure, the first substrate can be a color filter substrate, and the second substrate can be an array substrate.
According to a second aspect of the present disclosure, there is provided a liquid crystal display panel which can comprise the above-mentioned liquid crystal cell.
According to a third aspect of the present disclosure, there is provided a display device which can comprise the above-mentioned liquid crystal display panel.
The present liquid crystal display panel and display device share the same or similar beneficial effects as those of the above-mentioned liquid crystal cell, which are not repeated herein for simplicity.
According to a fourth aspect of the present disclosure, there is provided a method for fabricating a liquid crystal cell, comprising steps of: providing a color filter substrate and an array substrate; forming a volume variation compensating component in an active area, which comprises a material with a thermal expansion coefficient opposite to that of the liquid crystal, so as to compensate variation in the volume of liquid crystal when temperature varies; and assembling the color filter substrate and the array substrate, and curing a frame sealant to form a liquid crystal cell.
According to the present disclosure, the method can comprise: prior to dropping liquid crystal onto the array substrate, uniformly dispersing fillers in the liquid crystal.
According to the present disclosure, the method can comprise: forming main spacers and sub-spacers with a height smaller than that of the main spacers on the color filter substrate, wherein the volume variation compensating component forms the sub-spacers.
According to the present disclosure, the method can further comprise: in a dummy area, forming the volume variation compensating component as a buffer belt on the color filter substrate and/or the array substrate.
The present method for fabricating a liquid crystal cell shares the same or similar beneficial effects as those of the above-mentioned liquid crystal cell, which are not repeated herein for simplicity.
These and other aspects of the present disclosure are apparent from and will be further elucidated, by way of example, with reference to the drawings, in which:
The drawings are not necessarily drawn to scale. The same reference numerals or the reference numerals which differs by a multiple of 100 are used to denote the same or similar components throughout the drawings.
The present disclosure will be elucidated hereinafter in detail with reference to the accompanying drawings and embodiments. Apparently, these embodiments only constitute some embodiments of the present disclosure. The scope of the present disclosure is by no means limited to embodiments as set forth herein.
The drawings only illustrate constructions and/or parts relevant with the inventive concepts, while constructions and/or parts irrelevant with the inventive concepts are not indicated or partially indicated.
For ease of reading, components are suffixed with corresponding reference numerals: active area: AA; dummy area: DA; liquid crystal cell: 100, 200, 300, 400, 500; color filter substrate: 101, 201, 301, 401, 501; array substrate: 102, 202, 302, 402, 502; frame sealant: 103, 203, 303, 403, 503; liquid crystal: 104, 204, 304, 404, 504; ball spacer: 105; post spacer: 206; main spacer: 307, 407, 507; sub-spacer: 308, 408, 508; filler: 110, 210, 310, 410, 510; and buffer belt: 120, 220, 320, 420.
As shown in
As shown, the volume variation compensating component can be implemented as fillers 110 which are dispersed in the liquid crystal 104. Optionally, the fillers 110 can be nanospheres, nanowires, nanotubes, or nanoparticles, so that transparency in the active area AA of the liquid crystal cell 100 is not impaired. The fillers 110 can have regular shapes or irregular shapes. Optionally, the fillers 110 can be dispersed uniformly in the liquid crystal 104.
Optionally, the fillers 110 can be mixed with the liquid crystal in advance and then dropped onto the array substrate 102. Alternatively, the fillers 110 can be dispersed onto the array substrate 102 directly prior to, simultaneously with, or directly after dropping liquid crystal, so as to mix with the liquid crystal 104.
The liquid crystal cell 100 of
As shown in
The liquid crystal cell 200 of
As shown in
The liquid crystal cell 300 of
As shown in
As compared with the embodiment of
As compared with the embodiment of
As compared with the embodiment of
As shown in
As shown in
As shown in
The material with a negative thermal expansion coefficient as discussed herein can be any material with a negative thermal expansion coefficient, e.g., anisotropic negative thermal expansion materials listed in Table 1.
Optionally, the material with a negative thermal expansion coefficient in the liquid crystal cell 100, 200, 300, 400, 500 can be isotropic negative thermal expansion materials. For example, the material with a negative thermal expansion coefficient as discussed herein can be isotropic negative thermal expansion materials listed in Table 2.
A semi-quantitative analysis is conducted hereinafter to illustrate the mechanism of the volume variation compensating component. It is noted that this analysis intends to interpret principles of the present disclosure, not to limit the present disclosure in any manner.
It is assumed that the main post spacers have a height of HM, the sub post spacers have a height of HS, the liquid crystal cell has a thickness of d, the liquid crystal has an average linear thermal expansion coefficient of α, the effective area in the liquid crystal cell is S, the liquid crystal has a volume of VLC, the volume variation compensating component has a volume of VVC, the liquid crystal cell has a volume of VC, the volume variation compensating component has a linear expansion coefficient of β, a ratio between the volume of the volume variation compensating component and the liquid crystal is γ, and the temperature variation is ΔT.
Generally, the criterion for determining bubbles at low temperature is that the thickness d of the liquid crystal cell should be larger than the height HS of the sub post spacer, i.e., variation Δd in thickness of the liquid crystal cell should be less than or equal to a height difference |HM−HS| between the main post spacers and the sub post spacers. In addition, the criterion for determining gravity mura is that the thickness d of liquid crystal cell should be less than or equal to the height HM of main post spacers. In this way, calculations follow.
variation in volume of liquid crystal:
ΔVLC=(αΔT)3VLC [1];
variation in volume of volume variation compensating component:
ΔVB=(βΔT)3γVLC [2];
variation in volume of liquid crystal cell:
ΔVC=ΔVLC+ΔVB=(αΔT)3VLC+(βΔT)3γVLC [3]; and
variation in thickness of liquid crystal cell:
Δd=ΔVC/S=(αΔT)3VLC/S+(βΔT)3γVLC/S=VLC(ΔT)3(α3+γβ3)/S [4].
The liquid crystal cell shrinks with a decrease in temperature, bubbles appear if |Δd|>|HM−HS| is satisfied. The liquid crystal cell expands with an increase in temperature, gravity mura appears if d+|Δd|>HM is satisfied. In other cases, bubbles and gravity mura will not appear. Since the liquid crystal material generally is a positive thermal expansion material and the proposed volume variation compensating component is a negative thermal expansion material, α and β are opposite in sign. It is possible to effectively eliminate bubbles at low temperature, and alleviate gravity mura at high temperature. In addition, it can be seen from equation [4] that, by appropriately selecting the volume percentage γ and the linear expansion coefficient β of the volume variation compensating component, it is possible to partially, or even completely cancel out the influence of variation in volume of liquid crystal when temperature varies.
Optionally, the method can comprise: prior to dropping liquid crystal onto the array substrate, uniformly dispersing fillers in the liquid crystal. Alternatively, the fillers can be dispersed onto the array substrate directly prior to, simultaneously with, or directly after dropping liquid crystal, so as to mix with the liquid crystal.
Optionally, the method can comprise: forming main spacers and sub-spacers with a height smaller than that of the main spacers on the color filter substrate, wherein the volume variation compensating component forms the sub-spacers.
Optionally, the method can further comprise: in a dummy area, forming the volume variation compensating component as a buffer belt on the color filter substrate and/or the array substrate.
Although the present disclosure has been described above with reference to specific embodiments, it should be understood that the limitations of the described embodiments are merely for illustrative purpose and by no means limiting. Instead, the scope of the disclosure is defined by the appended claims rather than by the description, and all variations that fall within the range of the claims are intended to be embraced therein. Thus, other embodiments than the specific ones described above are equally possible within the scope of these appended claims.
Number | Date | Country | Kind |
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2014 1 0644400 | Nov 2014 | CN | national |
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Office Action from CN Application No. 201410644400.6 dated Aug. 30, 2016. |
Office Action from China Application No. 201410644400.6 dated Feb. 4, 2017. |
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