JP2012073464A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device that can suppress deterioration in display quality.SOLUTION: A liquid crystal display device 1 comprises: a first substrate 21 having a first main surface 21a; a second substrate 22 having a main surface 22b disposed to face the first main surface 21a of the first substrate 21; a liquid crystal layer 23 disposed between the first substrate 21 and the second substrate 22; a plurality of pixel electrodes 218 provided on the first main surface 21a of the first substrate 21; a common electrode 216 disposed on each side of the pixel electrode 218 in a cross-sectional view and provided on the first main surface 21a of the first substrate 21; and an insulation member 217 for insulation between the pixel electrode 218 and the common electrode 216. The pixel electrode 218 overlaps with the common electrode 216 disposed on each side of the pixel electrode 218. The pixel electrode 218 includes an overlapped part 218a located at each end part of the pixel electrode 218 and a non-overlapped part 218b that does not overlap with the common electrode 216 in a cross-sectional view. The insulation member 217 is arranged between the pixel electrode 218 and the common electrode 216 in the overlapped part 218a.

Description

  The present invention relates to an active matrix liquid crystal display device.

  The liquid crystal display device includes a pair of bases disposed opposite to each other, a liquid crystal layer provided between the pair of bases, a common electrode provided on a main surface of one of the pair of bases, a common electrode, and the one base And a plurality of pixel electrodes provided on the insulating film (see, for example, Patent Document 1).

  In this liquid crystal display device, a common electrode is arranged at a certain distance on both sides of the pixel electrode in plan view, and a voltage is applied to the pixel electrode and the common electrode, whereby the pixel electrode, the common electrode, An electric field is formed between them, and the direction of liquid crystal molecules in the liquid crystal layer is controlled by this electric field.

JP-A-10-133190

  By the way, in this liquid crystal display device, the pixel electrode is separated from the common electrode disposed on both sides of the pixel electrode. For this reason, when patterning is misaligned when the pixel electrode or the common electrode is formed by patterning, the distance between the pixel electrode and the common electrode arranged on one side, the pixel electrode and the other electrode It tends to be different from the distance between the common electrode arranged on the side. Thereby, the magnitude of the electric field formed by the pixel electrode and the common electrode on one side is different from the magnitude of the electric field formed by the pixel electrode and the common electrode on the other side, and the liquid crystal molecules controlled by these electric fields As a result of the deviation in the direction, there is a possibility that the light transmittance in each region is different, and the display quality may be lowered.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a liquid crystal display device capable of suppressing a reduction in display quality.

  The liquid crystal display device of the present invention includes a first substrate having a first main surface, a second substrate disposed so that the first main surface and the main surface of the first substrate face each other, the first substrate, and the first substrate. A liquid crystal layer disposed between the second substrate, a plurality of pixel electrodes provided on the first main surface of the first substrate, and provided on the first main surface of the first substrate; A common electrode disposed on both sides of the pixel electrode in a cross-sectional view; and an insulating member for insulating between the pixel electrode and the common electrode, wherein the pixel electrode is disposed on both sides of the pixel electrode. An overlapping portion that is superimposed on the common electrode and located at both ends of the pixel electrode in a cross-sectional view, and a non-overlapping portion that does not overlap the common electrode, and the pixel electrode and the common electrode in the overlapping portion The insulating member is interposed between the two.

  According to the liquid crystal display device of the present invention, it is possible to suppress deterioration in display quality.

It is the top view which showed the liquid crystal display device in the 1st Embodiment of this invention. It is sectional drawing along the II line | wire of FIG. It is the top view which showed the principal part of the liquid crystal panel. It is sectional drawing along the II-II line of FIG. It is sectional drawing which showed the overlapping part and non-overlapping part of a pixel electrode. It is sectional drawing which showed the principal part of the liquid crystal display device in the 2nd Embodiment of this invention. It is sectional drawing which showed the principal part of the liquid crystal display device in the 3rd Embodiment of this invention. It is the top view which showed the principal part of the liquid crystal display device in the 4th Embodiment of this invention. It is the top view which showed the principal part of the liquid crystal display device in the 5th Embodiment of this invention. It is the top view which showed the principal part of the liquid crystal display device in the 6th Embodiment of this invention.

[Embodiment 1]
First, the liquid crystal display device 1 according to the first embodiment of the present invention will be described. The liquid crystal display device 1 is a so-called transverse electric field type liquid crystal that controls the direction of liquid crystal molecules in a liquid crystal layer by forming an electric field between a pixel electrode provided on one of a pair of substrates and a common electrode. It is a display device.

As shown in FIGS. 1 and 2, the liquid crystal display device 1 includes a liquid crystal panel 2 with a non-display area E _O located outside the display region E _D and the display area E _D, the display area of the liquid crystal panel 2 E A light source device 3 that emits light to _D , a first polarizing plate 4 that is disposed outside the liquid crystal panel 2, and a second polarizing plate 5 that is disposed to face the first polarizing plate 4 with the liquid crystal panel 2 interposed therebetween. And.

  The liquid crystal panel 2 includes a first base body 21, a second base body 22 disposed opposite to the first base body 21, a liquid crystal layer 23 positioned between the first base body 21 and the second base body 22, and the liquid crystal layer 23. A sealing member 24 provided between the first base 21 and the second base 22 is provided so as to surround it.

  Further, on the first base 21, the gate wiring 211, the first insulating film 212 provided on the first base 21 so as to cover the gate wiring 211, and the first insulating film 212 are provided in a plan view. Provided in the first insulating film 212 so as to cover the source wiring 213 provided so as to intersect the gate wiring 211, the thin film transistor 214 located in the vicinity of the intersection region of the gate wiring 211 and the source wiring 213, and the source wiring 213. The second insulating film 215 formed, the common electrode 216 provided on the second insulating film 215, the insulating member 217 provided on the second insulating film 216 so as to cover a part of the common electrode 216, and the insulating member 217 And a pixel electrode 218 provided on the substrate.

  The first base 21 has a first main surface 21a on which the above members are provided, and a second main surface 21b located on the opposite side of the first main surface 21a. Examples of the material of the first base 21 include translucent glass and plastic. Here, translucency means having transparency to visible light.

  The gate wiring 211 has a function of applying a voltage supplied from a power source to the thin film transistor 214. As shown in FIG. 3, the gate wiring 212 is formed extending in the X direction. The plurality of gate lines 211 are arranged on the first main surface 21a of the first base 21 along the Y direction. Examples of the material of the gate wiring 211 include a conductive material such as aluminum, molybdenum, titanium, neodymium, or an alloy containing these.

The first insulating film 212 has a function of electrically insulating the gate wiring 211 and the source wiring 213. The first insulating film 212 is provided on the first main surface 21 a of the first base 21 so as to cover the gate wiring 211. Examples of the material of the first insulating film 212 include an insulating material such as silicon nitride and silicon oxide.

  The source wiring 213 has a function of applying a signal voltage supplied from a power source to the pixel electrode 215 through the thin film transistor 214. As shown in FIG. 3, the source wiring 213 is formed extending in the Y direction. The plurality of source lines 213 are arranged in the first insulating film 213 along the X direction. The material of the source wiring 213 can be the same as that of the gate wiring 211.

  The thin film transistor 214 has a function of applying a signal voltage applied through the source wiring 213 to the pixel electrode 218 in accordance with a voltage applied through the gate wiring 211. The thin film transistor 214 includes a semiconductor layer made of amorphous silicon, polysilicon, or the like.

  The second insulating film 215 has a function of electrically insulating the source wiring 213 and the common electrode 216. The second insulating film 215 is provided on the first insulating film 212 so as to cover the source wiring 213. The material of the second insulating film 215 is the same as that of the first insulating film 212.

The common electrode 216 has a function of forming an electric field with the pixel electrode 218 by a voltage applied from a power source. The common electrode 216 is provided on the second insulating film 215 in the display area _{E D.}

  As shown in FIG. 3, the common electrode 215 is positioned so as to surround the pixel electrode 218 in plan view. The common electrode 216 has a comb tooth portion 216 a extending in the arrow Y direction, and the comb tooth portion 216 a is located between adjacent pixel electrodes 218. As shown in FIG. 4, the common electrode 216 is disposed on both sides of the pixel electrode 218 in the X direction in a cross-sectional view.

  Examples of the material of the common electrode 216 include those having translucency and conductivity. For example, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), ATO (Antimony Tin Oxide), and AZO (Al-Doped Zinc Oxide). , Tin oxide, zinc oxide, and conductive polymers (such as PEDOT and PSS).

  The pixel electrode 218 has a function of forming an electric field with the pixel electrode 218 by a voltage applied from a power source. The material of the pixel electrode 218 is the same as that of the common electrode 216.

A plurality of pixel electrodes 218 is provided on the second insulating film 216 in the display area _{E D.} The plurality of pixel electrodes 218 are arranged along the X direction and the Y direction. Further, the pixel electrodes 218 adjacent to each other through the comb-tooth portion 216A of the common electrode 216 are connected to each other through the connection electrode 218A.

  In addition, as illustrated in FIG. 4, the pixel electrode 218 overlaps with the common electrode 216 disposed on both sides in the X direction and does not overlap with the overlapping portion 218 a located at both ends of the pixel electrode 218 and the common electrode 216. And a non-overlapping portion 218b. In FIG. 4, the hatched area in the pixel electrode 218 indicates the overlapping portion 218 a.

  The overlapping portion 218 a of the pixel electrode 218 overlaps with the common electrode 216 with the insulating member 217 interposed therebetween.

The insulating member 217 has a function of electrically insulating the pixel electrode 218 and the common electrode 216. As shown in FIG. 4, the insulating member 217 is interposed between the overlapping portion 218 a of the pixel electrode 218 and the common electrode 216. The material of the insulating member 217 is the same as that of the first insulating film 212.

  The pixel electrode 218 has an overlapping portion 218a. As a result, even when a deviation occurs when the pixel electrode 218 is formed by patterning, the distance between the pixel electrode 218 and the common electrode 216 arranged on one side thereof, the pixel electrode 218, and the other side. It can reduce that the distance between the common electrode 216 arranged on the side changes. This reduces the difference between the magnitude of the electric field formed by the pixel electrode 218 and the common electrode 216 on one side and the magnitude of the electric field formed by the pixel electrode 218 and the common electrode 216 on the other side. It is possible to reduce the difference in light transmittance in the region and suppress the deterioration of display quality.

The pixel electrode 218 has a non-overlapping portion 218b. That is, the entire pixel electrode 218 does not overlap with the common electrode 216. In the region where the overlapping portion 218a is formed, the pixel electrode 218 and the common electrode 216 overlap with each other, so that the light transmittance is likely to decrease. However, in the region where the non-overlapping portion 218a is formed, the pixel electrode 218 and By not overlapping the common electrode 216, a decrease in light transmittance can be reduced. Thus, it is possible to ensure the transmittance of light in a display area E _D.

  In addition, since the pixel electrode 218 includes the overlapping portion 218a, an auxiliary capacitor can be formed between the overlapping portion 218a and the common electrode 216. As a result, it is not necessary to provide a separate auxiliary capacitance line.

  In addition, since the pixel electrode 218 includes the overlapping portion 218a, the pixel electrode 218 and the common electrode 216 are disposed close to each other, so that an electric field generated between the pixel electrode 218 and the common electrode 216 can be increased and low. The direction of the liquid crystal molecules in the liquid crystal layer 23 can also be controlled by the signal voltage.

  Further, as shown in FIG. 5, the thickness La of the overlapping portion 218a of the pixel electrode 218 is preferably smaller than the thickness Lb of the non-overlapping portion 218b. Since the overlapping portion 218a overlaps with the common electrode 217, the light transmittance in this region tends to decrease. Therefore, by making the thickness of the overlapping portion 218a smaller than the thickness of the non-overlapping portion 218b, the difference between the transmittance in the region where the overlapping portion 218a is located and the transmittance in the region where the non-superimposing portion 218b is located. Can be reduced.

  As shown in FIG. 4, the second substrate 22 includes a light shielding pattern 221 that shields light, and a color filter 222 that is disposed adjacent to the light shielding pattern 221.

  The second base 22 has a function of supporting the member. Further, the first base 22 is provided with the above-mentioned members and a second main surface 22b facing the first main surface 21a of the first base 21 and a first main surface located on the opposite side of the second main surface 22b. Surface 22a. The material of the second base 22 is the same as that of the first base 21.

The light shielding pattern 221 is provided on the second main surface 22b of the second base 22 in a lattice shape so as to extend in the X direction and the Y direction. That is, the light-shielding pattern 221 is defines a display area E _D for each pixel. Examples of the material of the light shielding pattern 221 include a resin to which a dye or pigment having a high light shielding property (for example, black) is added, or a metal such as chromium or chromium oxide.

The color filter 222 has a function of transmitting only a specific wavelength of visible light. A plurality of color filters 222 are provided on the second main surface 22 b of the second base 22. Each color filter 222 has one color of red (R), green (G), and blue (B). The color of the color filter 222 is not limited to the above color, and may have a color such as yellow (Y) or white (W), for example. Examples of the material of the color filter 222 include a material obtained by adding a dye or a pigment to an acrylic resin.

  The liquid crystal layer 23 is provided between the first base 10 and the second base 20. The liquid crystal layer 23 includes liquid crystal molecules such as a nematic liquid crystal, a cholesteric liquid crystal, or a smectic liquid crystal.

  The seal member 24 has a function of bonding the first base 21 and the second base 22 together. The seal member 24 is provided between the first base 21 and the second base 22 so as to surround the liquid crystal layer 23.

The light source apparatus 3 has a function of irradiating light toward the first substrate 21 and second substrate 22 in the display area E _D. The light source device 3 includes a light source 31 and a light guide plate 32. In the light source device 3, a point light source such as an LED is used as the light source 31, but a linear light source such as a cold cathode tube may be used.

  The first polarizing plate 4 has a function of selectively transmitting light in a predetermined vibration direction. The first polarizing plate 4 is located outside the first base 21 and the second base 22, and is provided on the first main surface 22 a side of the second base 22.

  The second polarizing plate 5 has a function of selectively transmitting light in a predetermined vibration direction. The second polarizing plate 5 is disposed to face the first polarizing plate 4 with the first base 21 and the second base 22 interposed therebetween.

[Embodiment 2]
FIG. 6 is a diagram illustrating an example of a liquid crystal display device 1A according to the second embodiment.

  The difference between the liquid crystal display device 1A and the liquid crystal display device 1 is that in the liquid crystal display device 1A, the insulating member 217 is not overlapped with the first main surface 21a of the first base 21 from between the overlapping portion 218a and the common electrode 216. It is a point provided continuously between 218b.

  Thereby, in the liquid crystal display device 1A, the layer structure of the insulating film in the region where the pixel electrode 218 is formed can be the same as the layer structure of the insulating film in the region where the common electrode 216 is formed. Thereby, the difference between the transmittance in the region where the pixel electrode 218 is formed and the transmittance in the region where the common electrode 216 is formed can be reduced. Therefore, it can further suppress that display quality falls.

[Embodiment 3]
FIG. 7 is a diagram illustrating an example of a liquid crystal display device 1B according to the third embodiment.

  The difference between the liquid crystal display device 1B and the liquid crystal display device 1 is that in the liquid crystal display device 1B, the non-overlapping portion 218b of the pixel electrode 218 is located on the same plane as the common electrode 216.

  Thereby, in the liquid crystal display device 1B, the layer structure of the insulating film in the region where the non-overlapping portion 218b of the pixel electrode 218 is formed is the same as the layer structure of the insulating film in the region where the common electrode 216 is formed. it can. Thereby, the difference between the transmittance in the region where the non-overlapping portion 218b is formed and the transmittance in the region where the common electrode 217 is formed can be reduced. Therefore, it can further suppress that display quality falls.

Further, since the insulating member 217 is located only between the overlapping portion 218a of the pixel electrode 218 and the common electrode 216, the non-overlapping portion 218a of the pixel electrode 218 and the light of the common electrode 216 in the non-overlapping portion 218a A decrease in transmittance can be suppressed.

[Embodiment 4]
FIG. 8 is a diagram illustrating an example of a liquid crystal display device 1C according to the fourth embodiment. In FIG. 8, the overlapping portion 218a of the pixel electrode 218 is indicated by hatching.

  The difference between the liquid crystal display device 1 </ b> C and the liquid crystal display device 1 is that in the liquid crystal display device 1 </ b> C, the outer peripheral portion of the pixel electrode 218 overlaps with the inner peripheral portion of the common electrode 216.

  Thereby, in the liquid crystal display device 1 </ b> C, a larger auxiliary capacitance can be formed between the inner periphery of the pixel electrode 218 and the outer periphery of the common electrode 216.

[Embodiment 5]
FIG. 9 is a diagram illustrating an example of a liquid crystal display device 1D according to the fifth embodiment.

  The difference between the liquid crystal display device 1D and the liquid crystal display device 1 is that in the liquid crystal display device 1D, the pixel electrode 218 is provided on the second insulating film 217, and the insulating member 217 is provided so as to cover the pixel electrode 218. Is that the common electrode 216 is provided on the second insulating film 217 so as to overlap with both ends of the pixel electrode 218 via the insulating member 217.

  As a result, the liquid crystal display device 1 </ b> D has the same effects as those described for the liquid crystal display device 1.

[Embodiment 6]
FIG. 10 is a diagram illustrating an example of a liquid crystal display device 1E according to the sixth embodiment.

  The liquid crystal display device 1E is obtained by changing a part of the liquid crystal display device 1D. The difference between the liquid crystal display device 1E and the liquid crystal display device 1D is that the insulating member 217 is provided between the overlapping portion 218a and the common electrode 216. This is a point that is provided continuously between the first main surface 10 a of the first base 10 and the common electrode 217.

  Thereby, in the liquid crystal display device 1E, there exists an effect similar to the effect demonstrated by the liquid crystal display device 1 and liquid crystal display device 1D.

  While specific embodiments of the present invention have been described above, the present invention is not limited to these.

1, 1A, 1B, 1C, 1D, 1E Liquid crystal display device 2 Liquid crystal panel 21 First substrate 216 Common electrode 217 Insulating member 218 Pixel electrode 218a Overlapping portion 218b Non-overlapping portion 22 Second substrate 23 Liquid crystal layer

Claims (8)

A first substrate having a first main surface, a second substrate disposed so that the first main surface of the first substrate faces the main surface, and disposed between the first substrate and the second substrate. Liquid crystal layer, a plurality of pixel electrodes provided on the first main surface of the first base, and both sides of the pixel electrode provided on the first main surface of the first base in a cross-sectional view. And an insulating member for insulating between the pixel electrode and the common electrode,
The pixel electrode includes an overlapping portion that overlaps with the common electrode disposed on both sides of the pixel electrode, is positioned at both ends of the pixel electrode in a cross-sectional view, and a non-overlapping portion that does not overlap with the common electrode. ,
The liquid crystal display device, wherein the insulating member is interposed between the pixel electrode and the common electrode in the overlapping portion.   2. The liquid crystal display according to claim 1, wherein the insulating member is continuously provided from between the overlapping portion and the common electrode to between the first main surface of the first base and the non-overlapping portion. apparatus.   The liquid crystal display device according to claim 2, wherein the insulating member covers the common electrode disposed on both sides of the pixel electrode.   The liquid crystal display device according to claim 3, wherein the insulating member is provided on the first main surface of the base so as to cover the non-overlapping portion of the pixel electrode.   5. The liquid crystal display according to claim 4, wherein the insulating member is continuously provided from between the overlapping portion and the common electrode to between the first main surface of the first base and the common electrode. apparatus.   The liquid crystal display device according to claim 1, wherein the non-overlapping portion of the pixel electrode is located on the same plane as the common electrode.   The liquid crystal display device according to claim 1, wherein a thickness of the overlapping portion of the pixel electrode is smaller than a thickness of the non-overlapping portion of the pixel electrode. The common electrode is provided so as to surround the pixel electrode in plan view,
The liquid crystal display device according to claim 1, wherein an outer peripheral portion of the pixel electrode is superimposed on an inner peripheral portion of the common electrode.

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