CN102062978A - Liquid crystal display panel - Google Patents

Abstract

The invention relates to a liquid crystal display panel, which comprises a substrate, a plurality of pixel structures arranged on the substrate, an opposite substrate positioned on the opposite side of the substrate, and a liquid crystal layer positioned between the substrate and the opposite substrate. Each pixel structure comprises a scanning line, a data line, an active element, a pixel electrode and a common electrode. The common electrodes and the pixel electrodes are electrically insulated and are alternately arranged. The pixel electrode and the common electrode are respectively composed of a lower electrode and an upper electrode positioned on the lower electrode, and the width (W1) of the upper electrode is smaller than the width (W2) of the lower electrode. The liquid crystal layer includes liquid crystal molecules, wherein the liquid crystal molecules have optical anisotropy in an electric field and are optically isotropic under a no-electric-field condition.

Description

LCD panel

technical field

The invention relates to a liquid crystal display panel, and in particular to a liquid crystal display panel capable of improving dark line phenomenon.

Background technique

With the vigorous development of display technology, consumers have higher and higher requirements for display image quality. In addition to the requirements for the resolution, contrast ratio, viewing angle, gray level inversion, and color saturation of the display, the consumers also have high requirements for the display. The specification requirements of the response time (response time) are also increasing day by day.

In order to meet the needs of consumers, display related companies have invested in the development of blue phase liquid crystal displays with fast response characteristics. Taking the positive blue phase liquid crystal as an example, it requires a transverse electric field to operate so that it can function as a light valve. At present, some people have used the electrode design of the in-plane switching IPS (In-Plane Switching) display panel to drive the positive blue phase liquid crystal molecules in the blue phase (blue phase) liquid crystal display.

However, in the electrode design of the traditional coplanar switching display panel, there are many areas above the electrode without a transverse electric field, so that many liquid crystal molecules in the blue phase liquid crystal display cannot be driven smoothly, which leads to the dark line phenomenon. produce. Based on the above, how to improve the phenomenon of dark lines in blue phase LCDs is actually one of the problems that developers want to solve.

Contents of the invention

The invention provides a liquid crystal display panel, which can improve the dark line phenomenon in the known liquid crystal display panel.

The present invention provides a liquid crystal display panel, which includes a substrate, a plurality of pixel structures arranged on the substrate, an opposite substrate on the opposite side of the substrate, and a liquid crystal layer between the substrate and the opposite substrate. Each pixel structure includes scan lines, data lines, active elements, pixel electrodes and common electrodes. The active element is electrically connected with the scan line and the data line. The pixel electrode is electrically connected with the active device. The common electrodes are electrically insulated from the pixel electrodes and arranged alternately with each other. The pixel electrode and the common electrode are respectively composed of a lower electrode and an upper electrode located on the lower electrode, and the width ( W1 ) of the upper electrode is smaller than the width ( W2 ) of the lower electrode. The liquid crystal layer includes liquid crystal molecules, wherein the liquid crystal molecules have optical anisotropy in an electric field and are optically isotropic under the condition of no electric field.

Based on the above, in the liquid crystal display panel of the present invention, through the special design of the pixel electrode and the common electrode, the proportion of the area without a transverse electric field in the liquid crystal display panel is reduced. In this way, the probability that the liquid crystal molecules in the liquid crystal display panel are not driven can be reduced, thereby improving the phenomenon of dark lines in the conventional liquid crystal display panel.

Description of drawings

1 is a schematic cross-sectional view of a liquid crystal display panel according to an embodiment of the present invention;

FIG. 2 is a top view of a substrate of the liquid crystal display panel of FIG. 1;

3A, 3B, 3C, and 3D are schematic cross-sectional views of a local pixel structure according to an embodiment of the present invention;

4 is a schematic diagram of distribution of electric force lines between a pixel electrode and a common electrode according to an embodiment of the present invention;

FIG. 5 is a schematic diagram showing the relationship between driving voltage and light transmittance of a conventional liquid crystal display panel and a liquid crystal display panel according to an embodiment of the present invention.

Among them, reference signs

100: Liquid crystal display panel 110: Substrate

120: Pixel structure 122: Pixel electrode

122': strip pixel electrode pattern 122a, 124a: upper electrode

122b, 124b: Lower electrode 124: Common electrode

124': Strip common electrode pattern 130: Liquid crystal layer

132: Liquid crystal molecules 140: Counter substrate

SL: scan line DL: data line

T: Active component G: Gate

CH: Channel S: Source

D: Drain GI, BP: Insulation layer

TH: Contact window W: Spacing

W1, W2: Width S1, S2, S3, S4: Surface

E1, E2: electric field Ta, Tb, Tc, Td, Te: transmittance

Va, Vb, Vc, Vd, Ve: saturation voltage

Detailed ways

FIG. 1 is a schematic cross-sectional view of a liquid crystal display panel according to an embodiment of the invention. FIG. 2 is a plan view of a substrate of the liquid crystal display panel of FIG. 1 . FIG. 1 and FIG. 2 only show one pixel structure of the liquid crystal display panel as an example for illustration. Generally speaking, a liquid crystal display panel is composed of a plurality of pixel structures arranged in an array, and those skilled in the art should be able to understand the structure of the liquid crystal display panel of the present invention according to the description of this specification and the accompanying drawings. Please refer to FIG. 1 and FIG. 2 at the same time. The liquid crystal display panel 100 of this embodiment includes a substrate 110 , a plurality of pixel structures 120 , a liquid crystal layer 130 and an opposite substrate 140 .

The substrate 110 is mainly used to carry the pixel structure 120, and its material can be glass, quartz, organic polymer, or opaque/reflective material (such as: conductive material, wafer, ceramic, or other applicable materials. ), or other applicable materials.

A plurality of pixel structures 120 are disposed on the substrate 110 . Each pixel structure 120 in this embodiment may include a scan line SL, a data line DL, an active device T, a pixel electrode 122 and a common electrode 124 .

The scan lines SL and the data lines DL are disposed on the substrate 110 . The scan lines SL and the data lines DL are arranged alternately. In other words, the extending direction of the data lines DL is not parallel to the extending direction of the scanning lines SL. Preferably, the extending direction of the data lines DL is perpendicular to the extending direction of the scanning lines SL. In addition, the scan lines SL and the data lines DL belong to different film layers. Based on the consideration of conductivity, the scan lines SL and the data lines DL are generally made of metal materials. However, the present invention is not limited thereto. According to other embodiments, the scan lines SL and the data lines DL may also use other conductive materials. For example: alloys, nitrides of metal materials, oxides of metal materials, oxynitrides of metal materials, or stacked layers of metal materials and other conductive materials.

The active device T is electrically connected to the scan line SL and the data line DL. In more detail, the active device T of this embodiment may include a gate G, a channel CH, a source S and a drain D. As shown in FIG. In this embodiment, a part of the scanning line SL is used as the gate G. The channel CH is located above the gate G. Part of the area of the data line DL is used as the source S. The source S and the drain D are located above the channel CH. The above-mentioned active device T is illustrated by taking a bottom-gate thin film transistor as an example, but the present invention is not limited thereto. According to other embodiments, the above-mentioned active device T may also be a top-gate thin film transistor. According to this embodiment, the gate G of the active device T is further covered with an insulating layer GI, which may also be called a gate insulating layer. In addition, another insulation layer BP is further covered on the active device T, which can also be called a protection layer. The materials of the insulating layers GI and BP can be inorganic materials (such as silicon oxide, silicon nitride, silicon oxynitride, or a stacked layer of at least two of the above materials), organic materials, or a combination thereof.

The pixel electrode 122 is disposed on the substrate 110 and electrically connected to the drain D of the active device T. Referring to FIG. According to this embodiment, the pixel electrode 122 is disposed on the insulating layer GI, and the pixel electrode 122 is electrically connected to the drain D of the active device T through the contact window TH. The pixel electrode 122 includes metal oxide conductive material, metal or a combination thereof. In this embodiment, the pixel electrode 122 is, for example, indium tin oxide, indium zinc oxide, aluminum tin oxide, aluminum zinc oxide, indium germanium zinc oxide, other suitable oxides, molybdenum (Mo), tantalum ( Ta), chromium (Cr), tungsten (W), aluminum (Al), other suitable metals, or a stacked layer of at least two of the above.

The common electrode 124 is disposed on the substrate 110 and electrically insulated from the pixel electrode 122 . In particular, the common electrodes 124 and the pixel electrodes 122 are arranged alternately. In detail, the common electrode 124 may include a plurality of striped common electrode patterns 124', the pixel electrode 122 may include a plurality of striped pixel electrode patterns 122', and these striped pixel electrode patterns 124', 122' are arranged alternately, As shown in Figure 2.

In addition, each strip-shaped pixel electrode pattern 122' can be formed by its lower electrode 122b and the upper electrode 122a located on the lower electrode 122b, and each strip-shaped common electrode pattern 124' can also be formed by its lower electrode 124b and the upper electrode 122a located on the lower electrode 124b. formed by the upper electrode 124a. In this embodiment, the material used for the common electrode 124 is similar to the material used for the pixel electrode 122 , which will not be repeated here.

It is worth mentioning that the materials used for the upper electrodes 122a, 124a and the lower electrodes 122b, 124b may be the same or different. Preferably, the material used for the lower electrodes 122b, 124b is a light-transmitting material, such as indium tin oxide or other metal oxides, and the material used for the upper electrodes 122a, 124a is a metal material, such as molybdenum (Mo ) or other metals. However, the present invention is not limited thereto.

The opposite substrate 140 is located on the opposite side of the substrate 100 . In this embodiment, the opposite substrate 140 is, for example, a color filter substrate, which may include a color filter and a black matrix layer. However, the present invention is not limited thereto, and in other embodiments, the opposite substrate 140 may also be other suitable types of substrates.

The liquid crystal layer 130 is located between the substrate 100 and the opposite substrate 140 and is suitable as a light valve. The liquid crystal layer 130 includes liquid crystal molecules 132 . In particular, the liquid crystal molecules 132 are optically anisotropic in an electric field and optically isotropic in the absence of an electric field. For example, the liquid crystal molecules 132 are blue phase liquid crystal molecules, which have optical anisotropy (anisotropy) when an electric field is applied thereon, and optically anisotropic when no electric field is applied thereon. isotropic.

In other words, the optical properties of the blue phase liquid crystal molecules can be changed instantaneously by the magnitude of the applied electric field, so the liquid crystal panel 100 using the blue phase liquid crystal molecules can have a better response time (response time) )Performance. However, the liquid crystal molecules 132 of the present invention are not limited thereto, and in other embodiments, the liquid crystal molecules can also be positive liquid crystal molecules or other suitable liquid crystal molecules.

FIG. 3A is a schematic cross-sectional view of a local pixel structure along the section line II' in FIG. 2 . Please refer to FIG. 2 and FIG. 3A at the same time. In this embodiment, the pixel electrode 122 is composed of the lower electrode 122b and the upper electrode 122a located on the lower electrode 122b, and the common electrode 124 is also composed of the lower electrode 124b and the upper electrode 122a located on the lower electrode 122b. The upper electrode 124a is formed on the lower electrode 124b. It should be noted that the width W2 of the lower electrodes 122b, 124b is larger than the width W1 of the upper electrodes 122a, 124a. Preferably, the ratio W1/W2 of the width W1 of the upper electrodes 122a, 124a to the width W2 of the lower electrodes 122b, 124b is between 0.4-0.8, and the optimum range is 0.45-0.65.

For example, the width W1 of the upper electrodes 122a, 124a may be 3 microns, and the width W2 of the lower electrodes 122b, 124b may be 4-7 microns. More specifically, in one embodiment, the width W1 of the upper electrodes 122a, 124a may be 3 microns, and the width W2 of the lower electrodes 122b, 124b may be 4 microns, as shown in FIG. 3A . In another embodiment, the width W1 of the upper electrodes 122a, 124a may be 3 microns, and the width W2 of the lower electrodes 122b, 124b may be 5 microns, as shown in FIG. 3B . In yet another embodiment, the width W1 of the upper electrodes 122a, 124a may be 3 microns, and the width W2 of the lower electrodes 122b, 124b may be 6 microns, as shown in FIG. 3C . In yet another embodiment, the width W1 of the upper electrodes 122 a and 124 a may be 3 microns, and the width W2 of the lower electrodes 122 b and 124 b may be 7 microns, as shown in FIG. 3D .

In addition, in this embodiment, the spacing W between these strip-shaped pixel electrode patterns 122' and the adjacent strip-shaped common electrode patterns 124' is the same, as shown in FIG. 2 . For example, the distance W between the pattern of the pixel electrode 122 and the pattern of the adjacent strip-shaped common electrode 124 is, for example, 3 micrometers, as shown in FIGS. 3A , 3B, 3C and 3D. However, the present invention is not limited thereto. In other embodiments, the distance W between the pattern of the pixel electrode 122 and the pattern of the adjacent strip-shaped common electrode 124 may also be other suitable distances.

FIG. 4 is a schematic diagram of distribution of electric force lines between a pixel electrode and a common electrode according to an embodiment of the present invention. Referring to FIG. 4 , there is a first lateral electric field E1 between the side surface S1 of the lower electrode 122 b of the pixel electrode 122 and the side surface S2 of the lower electrode 124 b of the adjacent common electrode 124 . There is a second lateral electric field E2 between the upper surface S3 of the lower electrode 122 b of the pixel electrode 122 and the upper surface S4 of the lower electrode 124 b of the adjacent common electrode 124 . In other words, through the design of the pixel electrode 122 and the common electrode 124 in this embodiment, the ratio of the area directly above the pixel electrode 122, directly above the common electrode 124, and between the pixel electrode 122 and the common electrode 124 without a lateral electric field can be reduced. . In this way, the liquid crystal molecules 132 located directly above the pixel electrode 122 and the common electrode 124 and between the pixel electrode 122 and the common electrode 124 have a higher probability to be driven, thereby improving the phenomenon of dark lines in the conventional liquid crystal display panel.

FIG. 5 is a schematic diagram showing the relationship between driving voltage and light transmittance of a conventional liquid crystal display panel and a liquid crystal display panel according to an embodiment of the present invention. Please refer to FIG. 5 . Curve a in FIG. 5 represents the relationship between the driving voltage and the light transmittance of a conventional liquid crystal display panel. Curves b, c, d, and e represent the relationship between the driving voltage and the light transmittance of the liquid crystal display panel according to an embodiment of the present invention.

For example, curve b represents that the width W2 of the lower electrodes 122b, 124b of the liquid crystal display panel 100 is 4 microns, the width W1 of the upper electrodes 122a, 124a is 3 microns, and the distance W between the pixel electrode 122 and the common electrode 124 is 3 microns. The relationship between driving voltage and transmittance at micron. Curve c represents the driving when the width W2 of the lower electrodes 122b, 124b of the liquid crystal display panel 100 is 5 microns, the width W1 of the upper electrodes 122a, 124a is 3 microns, and the distance W between the pixel electrode 122 and the common electrode 124 is 3 microns. The relationship between voltage and transmittance. Curve d represents the driving when the width W2 of the lower electrodes 122b, 124b of the liquid crystal display panel 100 is 6 microns, the width W1 of the upper electrodes 122a, 124a is 3 microns, and the distance W between the pixel electrode 122 and the common electrode 124 is 3 microns. The relationship between voltage and transmittance. Curve e represents the driving when the width W2 of the lower electrodes 122b, 124b of the liquid crystal display panel 100 is 7 microns, the width W1 of the upper electrodes 122a, 124a is 3 microns, and the distance W between the pixel electrode 122 and the common electrode 124 is 3 microns. The relationship between voltage and transmittance.

It can be seen clearly from FIG. 5 that the maximum transmittance Tb, Tc, Td and Te of the liquid crystal display panel according to an embodiment of the present invention are all higher than the maximum transmittance Ta of the known liquid crystal panel. In other words, the pixel structure design of an embodiment of the present invention can effectively improve the transmittance of the liquid crystal panel. Especially, when the ratio W1/W2 of the width W1 of the upper electrode (122a, 124a) to the width W2 of the lower electrode (122b, 124b) is between 0.45-0.65, the effect of improving the transmittance of the liquid crystal panel is the best. good. For example, compared with the known liquid crystal display panel, it can effectively increase the maximum transmittance by about 10%-15%.

In addition, it can also be seen from FIG. 5 that the saturation voltages Vb, Vc, Vd and Ve of the liquid crystal display panel according to an embodiment of the present invention are all lower than the saturation voltage Va of the known liquid crystal display panel. In other words, the liquid crystal display panel 100 of an embodiment of the present invention can be driven with a lower driving voltage. That is to say, the liquid crystal display panel 100 of an embodiment of the present invention can save power compared with the known liquid crystal display panel.

To sum up, in the liquid crystal display panel of the present invention, the pixel electrode and the common electrode respectively composed of the upper and lower electrodes can be used, so that there is no lateral electric field directly above the pixel electrode, the common electrode, and between the pixel electrode and the common electrode. The area ratio is reduced. In this way, the liquid crystal molecules located directly above the pixel electrode, the common electrode and between the pixel electrode and the common electrode have a higher probability to be driven, thereby improving the phenomenon of dark lines in the conventional liquid crystal panel.

Certainly, the present invention also can have other multiple embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (10)

1. A liquid crystal display panel, characterized in that, comprising: a substrate; A plurality of pixel structures are arranged on the substrate, wherein each pixel structure includes: a scan line and a data line; an active element electrically connected to the scan line and the data line; a pixel electrode connected to the The active element is electrically connected; a common electrode is electrically insulated from the pixel electrode, and the pixel electrode and the common electrode are arranged alternately, wherein the pixel electrode and the common electrode are respectively composed of a lower electrode and an upper electrode located on the lower electrode electrode, and the width of the upper electrode is smaller than the width of the lower electrode; a pair of facing substrates on opposite sides of the substrate; and A liquid crystal layer is located between the substrate and the opposite substrate. The liquid crystal layer includes liquid crystal molecules, wherein the liquid crystal molecules have optical anisotropy in an electric field and are optical isotropy under the condition of no electric field. 2. The liquid crystal display panel according to claim 1, wherein the liquid crystal molecules comprise blue phase liquid crystal molecules. 3. The liquid crystal display panel according to claim 1, wherein the upper electrode has a width of 3 microns, and the lower electrode has a width of 4-7 microns. 4. The liquid crystal display panel according to claim 1, wherein the pixel electrode and the common electrode comprise metal oxide conductive material, metal or a combination thereof. 5. The liquid crystal display panel according to claim 1, wherein the pixel electrode comprises a plurality of strip-shaped pixel electrode patterns, the common electrode comprises a plurality of strip-shaped common electrode patterns, and these strip-shaped pixel electrode patterns are the same as the strip-shaped pixel electrode patterns Striped common electrode patterns are arranged alternately. 6 . The liquid crystal display panel according to claim 5 , wherein each strip-shaped pixel electrode pattern and each strip-shaped common electrode pattern are formed by the lower electrode and the upper electrode, respectively. 7 . The liquid crystal display panel according to claim 5 , wherein the distances between the striped pixel electrode patterns and adjacent striped common electrode patterns are the same. 8. The liquid crystal display panel according to claim 1, wherein there is a first lateral electric field between the side surface of the lower electrode of the pixel electrode and the side surface of the lower electrode of the adjacent common electrode, and the pixel There is a second transverse electric field between the upper surface of the lower electrode of the electrode and the upper surface of the lower electrode of the adjacent common electrode. 9 . The liquid crystal display panel according to claim 1 , wherein a ratio of the width of the upper electrode to the width of the lower electrode is between 0.4˜0.8. 10 . The liquid crystal display panel according to claim 1 , wherein a ratio of the width of the upper electrode to the width of the lower electrode is between 0.45˜0.65.

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