JP5918046B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device used for various applications such as a mobile phone, a digital camera, a portable game machine, or a portable information terminal.

  A horizontal electric field type liquid crystal display device includes a pair of substrates facing each other and a liquid crystal layer interposed between the pair of substrates. A thin film transistor, a plurality of gate wirings, a plurality of source wirings provided so as to intersect the plurality of gate wirings, a plurality of gate wirings, and a plurality of gate wirings are formed on the main surface of one of the pair of substrates. An insulating film provided so as to cover the source wiring, and a signal electrode and a common electrode provided on the insulating film are formed (for example, see Patent Document 1).

  In this liquid crystal display device, the signal electrode and the common electrode are alternately arranged on the same plane, and an electric field is applied between the signal electrode and the common electrode by applying a voltage to the signal electrode and the common electrode. The direction of liquid crystal molecules in the liquid crystal layer is controlled by this electric field. A wide viewing angle can be achieved by controlling the direction of liquid crystal molecules by this lateral electric field.

JP 2000-275664 A

  In recent years, a liquid crystal display device is often used in combination with a touch panel or the like, and the frequency with which external stress is applied to the liquid crystal display device by a user pressing the touch panel is increasing.

  In a horizontal electric field type liquid crystal display device, when pressed during white display, the pressure changes the orientation of liquid crystal molecules located in the pressed region (called a reverse twist domain), and the orientation of the liquid crystal molecules returns as it is. It may disappear. In this case, there is a problem in that the reverse twist domain region and other regions have different transmittances, and the reverse twist domain region appears as spots, which may reduce display quality.

  To solve this problem, a signal electrode and a lower layer signal electrode are provided between the insulating film on which the signal electrode and the common electrode are formed and the main surface of one substrate, and the lower layer signal electrode and the upper layer are disposed on the common electrode The generation of the reverse twist domain was suppressed by generating an electric field between the two.

  On the other hand, there is a demand for higher definition in recent liquid crystal display devices. For this reason, the number of wirings tends to increase, and the signal electrodes are likely to be short-circuited with source wirings, gate wirings, and the like in the manufacturing process of the liquid crystal display device. Due to this short circuit, there is a problem that a bright spot defect having a higher luminance than that of a normal pixel may occur when the liquid crystal display device is driven or not driven. To solve this problem, the laser electrode is subjected to laser cut processing to darken the bright spot, thereby making the bright spot defect inconspicuous (referred to as dark spot repair).

However, if the lower signal electrode is provided so as to overlap with the signal electrode, if the lower signal electrode is also not subjected to the laser cutting process, an electric field is generated and the liquid crystal rotates to become a light luminescent spot. For this reason, it is necessary to perform laser cutting processing on the lower signal electrode. However, since an insulating film is provided on the lower signal electrode, it is difficult for the laser to reach the lower signal electrode. In addition to being difficult to perform the cutting process, the signal electrode is further formed on this insulating film, so the area to be irradiated with the laser is limited, the degree of freedom of the laser cutting process is reduced, and the lower-layer signal electrode is laser-cut. There is a problem that processing is difficult.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid crystal display device that facilitates a dark spot repair in addition to suppressing deterioration in display quality due to external stress. is there.

The liquid crystal display device according to the present invention includes a first substrate and a second substrate disposed so that main surfaces thereof are opposed to each other, a liquid crystal layer disposed between the first substrate and the second substrate, and the second substrate. A plurality of gate wirings provided on the main surface, a plurality of source wirings provided on the main surface of the second substrate so as to intersect the plurality of gate wirings, a plurality of the gate wirings, and An insulating film provided on the main surface of the second substrate so as to cover the plurality of source lines, and the insulating film in a pixel surrounded by the plurality of gate lines and the plurality of source lines in plan view A plurality of upper layer signal electrodes provided above and a plurality of upper layer common electrodes provided on the insulating film in the pixel to form an electric field between the upper layer signal electrodes, Upper signal electrode and a plurality of said The layer common electrodes are alternately arranged along a certain direction on the insulating film, and the upper common electrode is formed between the main surface of the second substrate and the insulating film in the pixel. all of the upper common electrode is electrically connected to and has the lower electrode is characterized and provided Turkey in the region.

  According to the liquid crystal display device of the present invention, it is possible to easily perform a darkening repair in addition to suppressing a deterioration in display quality due to an external stress.

It is a top view which shows the liquid crystal display device in embodiment of this invention. It is sectional drawing along the II line | wire of FIG. It is a top view which shows the wiring and electrode of the 2nd board | substrate in a pixel. It is sectional drawing along the II-II line of FIG.

  A liquid crystal display device 1 according to an embodiment of the present invention will be described with reference to FIGS.

  The liquid crystal display device 1 includes a liquid crystal panel 2, a light source device 3 that emits light toward the liquid crystal panel 2, a first polarizing plate 4 disposed on the liquid crystal panel 2, and the liquid crystal panel 2 and the light source device 3. And a second polarizing plate 5 disposed therebetween.

  In the liquid crystal panel 2, the first substrate 21 and the second substrate 22 are disposed to face each other, and a liquid crystal layer 23 is provided between the first substrate 21 and the second substrate 22, so as to surround the liquid crystal layer 23. In addition, a sealing material 24 for joining the first substrate 21 and the second substrate 22 is provided.

  The first substrate 21 has a first main surface 21a used as a display surface when displaying an image, and a second main surface 21b located on the opposite side of the first main surface 21a. The first substrate 21 is made of, for example, glass or plastic.

  On the second main surface 21b of the first substrate 21, a color filter 211 is provided.

The color filter 211 has a function of transmitting only a specific wavelength of visible light. A plurality of color filters 211 is positioned on the second main surface 21b of the first substrate 21, it is provided for each picture element P. Each color filter 211 has one of red, green, and blue.
Further, the color filter 211 is not limited to the above color, and for example, a color filter 211 such as yellow or white may be disposed. Examples of the material of the color filter 211 include a resin to which a dye or pigment is added.

Although the color filter 211 is provided in the present embodiment, the present invention is not limited to this. For example, when displaying a monochrome image, the color filter 211 may not be provided.

  An overcoat layer (not shown) is formed on the color filter 211.

  The second substrate 22 has a first main surface 22a facing the second main surface 21b of the first substrate 21, and a second main surface 22b located on the opposite side of the first main surface 22a. The second substrate 22 can be formed of the same material as the first substrate 21.

A plurality of gate wirings 221 and auxiliary capacitance wirings 222 are provided on the first main surface 22 a of the second substrate 22, and the gate insulating film 223 covers the plurality of gate wirings 221 and auxiliary capacitance wirings 222.
Is provided. A plurality of source wirings 224 are provided on the gate insulating film 223. A first interlayer insulating film 225 is provided on the gate insulating film 223 and the plurality of source wirings 224. A lower layer electrode D is provided on the first interlayer insulating film 225. A second interlayer insulating film 226 is provided on the first interlayer insulating film 225 and the lower layer electrode D. A light shielding film BM is provided on the second interlayer insulating film 226, and a planarizing film 227 is provided on the second interlayer insulating film 226 while covering the light shielding film BM. On the planarizing film 227, an upper common electrode 228 and an upper signal electrode 229 are provided.

The gate wiring 221 has a function of applying a voltage supplied from a driving IC (not shown) to the thin film transistor TFT. As shown in FIG. 3, the gate wiring 221 includes the first main surface 22 of the second substrate 22.
It extends in the X direction on a. The plurality of gate wirings 221 are arranged along the Y direction. The gate wiring 221 is formed of a conductive material, for example, aluminum, molybdenum, titanium, neodymium, chromium, copper, or an alloy containing these.

  The gate wiring 221 is formed by the following method, for example.

  First, a material is formed as a film on the first main surface 22a of the second substrate 22 by sputtering, vapor deposition, or chemical vapor deposition. A photosensitive resin is applied to the surface of the film, and a pattern having a desired shape is formed on the photosensitive resin by performing an exposure process and a development process on the applied photosensitive resin. Next, this film is etched with a chemical solution to make the film into a desired shape, and then the applied photosensitive resin is peeled off. Thus, the gate wiring 221 can be formed by forming and patterning the material.

  The auxiliary capacitance line 222 is provided on the first main surface 22 a of the second substrate 22. The auxiliary capacitance line 222 is located on the same plane as the gate line 221. As shown in FIG. 3, the auxiliary capacitance line 222 extends in the X direction. Further, the auxiliary capacitance wiring 222 may be formed of the same material as the gate wiring 221. In the present embodiment, the auxiliary capacitance line 222 is formed on the same plane as the gate line 221, but the present invention is not limited to this. That is, the auxiliary capacitance line 222 may be formed in a different layer from the gate line 221.

The gate insulating film 223 is provided on the first main surface 22a so as to cover the gate wiring 221 and the auxiliary capacitance wiring 222. The gate insulating film 223 is formed of an insulating material such as silicon nitride or silicon oxide. The gate insulating film 223 can be formed on the first main surface 22a of the second substrate 22 by the above-described sputtering method, vapor deposition method, chemical vapor deposition method, or the like.

  The source wiring 224 has a function of applying a signal voltage supplied from the driving IC to the upper signal electrode 229 through the thin film transistor TFT. As shown in FIG. 3, the plurality of source lines 224 extend in the Y direction. The plurality of source lines 224 are arranged along the X direction on the gate insulating film 223. The source wiring 224 may be formed using the same material as the gate wiring 221. The source wiring 224 can be formed by a method similar to that for the gate wiring 221. In this embodiment, the source wiring 224 is formed in a straight line, but may be bent.

  Note that a region surrounded by the plurality of gate lines 221 and the plurality of source lines 224 is a pixel P.

The thin film transistor TFT includes a semiconductor layer such as amorphous silicon, polysilicon, or IGZO, a source electrode provided on the semiconductor layer, connected to the source wiring 224, and a drain electrode. The drain electrode of the thin film transistor TFT is connected to the upper signal electrode 229 through the contact hole C.

In the thin film transistor TFT, the resistance of the semiconductor layer between the source electrode and the drain electrode changes according to the voltage applied to the semiconductor layer via the gate wiring 221, so that the upper signal electrode 229
Writing or non-writing of an image signal to / from is controlled.

The first interlayer insulating film 225 is provided on the gate insulating film 223 so as to cover the source wiring 224. The first interlayer insulating film 225 may be formed of the same material as the gate insulating film 223.

The lower layer electrode D is provided on the first interlayer insulating film 225. Further, the lower layer electrode D is located in a region where the upper layer common electrode 228 is formed. Further, in the present embodiment, all of the lower layer electrodes D are formed so as to be located in the formation region of the upper layer common electrode 228. That is, in the pixel P, the lower layer electrode D is not formed in the formation region of the upper layer signal electrode 229 and the region between the upper layer signal electrode 229 and the upper layer common electrode 228.

The lower layer electrode D is electrically connected to the upper layer common electrode 228. Specifically, the upper common electrode 228 and the lower electrode D are connected via the contact hole C. Further, the lower layer electrode D may be connected to the auxiliary capacitance line 222 through the contact hole C. In addition,
In this embodiment, the extending portion in the Y direction of the lower layer electrode D is formed in a straight line shape, but may be formed by bending. In FIG. 4, the formation region of the lower layer electrode D is a region indicated by hatching.

In addition, although the lower layer electrode D of this embodiment is provided in the 1st interlayer insulation film 225, it is not limited to this. That is, the lower layer electrode D only needs to be formed in a layer lower than the upper layer common electrode 228. For example, the lower layer electrode D may be formed on the first main surface 22a of the second substrate 22, or the gate The insulating film 223 may be formed.

  The material of the lower layer electrode D is formed of a conductive material. The material of the lower layer electrode D is, for example, a light-transmitting material such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), ATO (Antimony Tin Oxide), AZO (Al-Doped Zinc Oxide), tin oxide, and zinc oxide. Alternatively, an opaque material such as aluminum, molybdenum, titanium, neodymium, chromium, copper, or an alloy containing any of these can be given, but the material is not limited thereto as long as it is a conductive material.

  Note that if a light-transmitting material is used as the material of the lower layer electrode D, light shielding by the lower layer electrode D can be suppressed, so that the aperture ratio of the pixel P is improved.

The second interlayer insulating film 226 has a function of electrically insulating the lower layer electrode D and the light shielding film BM. Second
The interlayer insulating film 226 is provided on the first interlayer insulating film 225 so as to cover the lower layer electrode D. The second interlayer insulating film 226 may be formed of the same material as the gate insulating film 223. In the present embodiment, a structure in which the second interlayer insulating film 226 is provided is employed. However, the present invention is not particularly limited thereto, and a structure in which the second interlayer insulating film 226 is not provided may be employed.

The light shielding film BM has a function of shielding light. The light shielding film BM is provided on the second interlayer insulating film 226 and is positioned so as to overlap the gate wiring 221, the auxiliary capacitance wiring 222, the source wiring 224, and the upper common electrode 228 in plan view. The light shielding film BM consists of gate wiring 221 and source wiring 224.
In addition, since the second substrate 22 is formed so as to cover the auxiliary capacitance wiring 222, the gate wiring 221, the auxiliary capacitance wiring 222 and the source are compared with the case where the light shielding film BM is formed on the first substrate 21 side. The wiring 224 can be shielded with high accuracy.

  Examples of the material of the light shielding film BM include a resin to which a dye or pigment having a high light shielding property (for example, black) is added, a metal such as chromium, or an alloy.

  In the present embodiment, the light shielding film BM is formed on the second substrate 22 side, but the present invention is not limited to this. That is, the light shielding film BM may be formed on the first substrate 21 side.

The planarizing film 227 is provided on the second interlayer insulating film 226 so as to cover the light shielding film BM. The planarization film 227 is formed of an organic material, and examples thereof include an acrylic resin, an epoxy resin, and a polyimide resin. The film thickness of the planarizing film 227 is set in the range of 1 μm to 5 μm, for example. Note that it is preferable to increase the thickness of the planarization film 227 from the viewpoint of reducing parasitic capacitance.

The upper common electrode 228 has a function of generating an electric field with the upper signal electrode 229 by a voltage applied from the driving IC. The upper common electrode 228 is provided on the planarizing film 227. The upper common electrode 228 is formed of a light-transmitting material having conductivity, for example, ITO, IZO,
It is formed of ATO, AZO, tin oxide, zinc oxide or a conductive polymer.

  The upper layer signal electrode 229 has a function of generating an electric field with the upper layer common electrode 228 by a voltage applied from the driving IC. The plurality of upper layer signal electrodes 229 are provided on the planarizing film 227 and arranged along the X direction. Further, the upper common electrode 228 is positioned on both sides of the upper signal electrode 229 in the X direction. That is, the upper signal electrodes 229 and the upper common electrodes 228 are alternately arranged in the X direction. In this embodiment, the upper signal electrode 229 is formed linearly, but may be bent. The upper signal electrode 229 may be formed of the same material as the upper common electrode 228.

The width of the upper signal electrode 229 is set in the range of 2 μm to 5 μm, for example. Further, the distance between the upper signal electrode 229 and the upper common electrode 228 is set in a range of 5 μm to 20 μm, for example.

In the liquid crystal display device 1, the lower layer electrode D that is electrically connected to the upper layer common electrode 228 includes a first electrode.
It is provided on the interlayer insulating film 225 and is located in the formation region of the upper common electrode 228. As a result, an electric field is generated from the lower layer electrode D toward the upper layer signal electrode 229 located on both sides of the upper layer common electrode 228. This electric field, even when the display area E _D during white display is pressed, the disturbance of alignment of liquid crystal molecules in the region between the upper signal electrode 229 and the upper common electrode 228 is reduced In addition, it is possible to suppress deterioration in display quality due to the occurrence of the reverse twist domain.

  Further, as described above, by providing the lower layer electrode D, not only between the upper layer signal electrode 229 and the upper layer common electrode 228, but also from the lower layer electrode D to the upper layer signal electrode 229 located on both sides of the upper layer common electrode 228. An electric field is generated. As a result, since the liquid crystal molecules can be controlled with a lower voltage than when the lower layer electrode D is not provided, the power consumption when using the liquid crystal display device can be reduced, and the power consumption of the liquid crystal display device can be reduced. be able to.

In the liquid crystal display device 1, in the pixel P, the lower layer electrode D that is electrically connected to the upper common electrode 228 is provided in the formation region of the upper common electrode 228, and the upper layer signal electrode 229 is formed in the formation region. The lower layer electrode D electrically connected to the upper layer signal electrode 229 is not provided. That is, in the liquid crystal display device 1, only the lower layer electrode D electrically connected to the upper common electrode 228 is not the lower layer electrode D electrically connected to the upper layer signal electrode 229 on the first interlayer insulating film 225. Is formed. As a result, even when the upper layer signal electrode 229 is short-circuited with a wiring such as the source wiring 224, the laser cutting process may be performed on the upper layer signal electrode 229 instead of the lower layer electrode D. That is, in the liquid crystal display device 1, even if a bright spot defect occurs in the display image, if the upper layer signal electrode 229 is subjected to laser cutting processing, it becomes possible to perform a dark spot repair, and thus the dark spot repair is easily performed. It can be performed.

In the liquid crystal display device 1, the lower layer electrode D electrically connected to the upper layer common electrode 228 is positioned between the source wiring 224 and the upper layer signal electrode 229 in plan view. Thereby, the lower layer electrode D shields the electric field generated from the source line 224, and the influence on the voltage of the upper layer signal electrode 229 due to the fluctuation of the voltage of the source line 224 can be reduced.

  The liquid crystal layer 23 is provided between the first substrate 21 and the second substrate 22. The liquid crystal layer 23 includes liquid crystal molecules such as nematic liquid crystal.

The sealing material 24 has a function of bonding the first substrate 21 and the second substrate 22 together. Sealing material 24 is provided between the first substrate 21 as in a plan view to surround the display region E _D and the second substrate 22. This sealing material 24 is formed of an epoxy resin or the like.

  In the liquid crystal display device 1, an electric field is generated between the upper signal electrode 229 and the upper common electrode 228 by applying a voltage to the upper signal electrode 229 and the upper common electrode 228 provided on the same plane. The direction of the liquid crystal molecules in the liquid crystal layer is controlled by this electric field.

The light source device 3 has a function of emitting light toward the display region E _D of the liquid crystal panel 2. The light source device 3 includes a light source 31 and a light guide plate 32. In the light source device 3 according to the present embodiment, a point light source such as an LED is employed as the light source 31, but a linear light source such as a cold cathode tube may be employed.

  The first polarizing plate 4 has a function of selectively transmitting light in a predetermined vibration direction. The first polarizing plate 4 is disposed so as to face the first main surface 21 a of the first substrate 21 of the liquid crystal panel 2.

  The second polarizing plate 5 has a function of selectively transmitting light in a predetermined vibration direction. The second polarizing plate 5 is disposed so as to face the second main surface 22 b of the second substrate 22.

  The present invention is not particularly limited to the above-described embodiment, and various modifications and improvements can be made without departing from the scope of the present invention. For example, in the liquid crystal display device 1, the lower layer electrode D that is electrically connected to the upper layer signal electrode 229 may be provided as long as it is outside the formation region of the upper layer signal electrode 229.

As a result, an electric field is generated from the lower layer electrode D toward the upper layer common electrode 228, and the disorder of the alignment of the liquid crystal molecules in the region between the upper layer signal electrode 229 and the upper layer common electrode 228 is reduced. Deterioration of display quality due to the occurrence of the occurrence can be suppressed. Further, even when the lower layer electrode D electrically connected to the upper layer signal electrode 229 and the source wiring 224 are short-circuited to cause a bright spot defect, the upper layer signal electrode 229 is located above the lower layer electrode D. Since it is not formed, it becomes easy to perform the laser cutting process on the lower layer electrode D, and the dark spot repair can be easily performed.

1 Liquid crystal display device 2 Liquid crystal panel P Pixel
21 First board
21a 1st main surface
21b Second main surface (main surface)
211 Color filter
22 Second board
22a First main surface (main surface)
22b 2nd main surface
221 Gate wiring
222 Auxiliary capacitance wiring
223 Gate insulation film
224 source wiring
225 First interlayer insulating film
226 Second interlayer insulating film
227 Planarization film (insulating film)
228 Upper common electrode
229 Upper signal electrode
TFT Thin film transistor D Lower layer electrode
BM Shading film C Contact hole
23 Liquid crystal layer
24 Sealing material 4 First polarizing plate 5 Second polarizing plate 3 Light source device
31 Light source
32 Light guide plate

Claims (3)

Provided on the main surface of the second substrate, a first substrate and a second substrate disposed with the main surfaces facing each other, a liquid crystal layer disposed between the first substrate and the second substrate, A plurality of gate lines, a plurality of source lines provided on the main surface of the second substrate so as to intersect the plurality of gate lines, and the plurality of gate lines and the plurality of source lines. A plurality of upper layers provided on the insulating film in a pixel surrounded by the plurality of gate wirings and the plurality of source wirings in a plan view; and an insulating film provided on the main surface of the second substrate A plurality of upper layer common electrodes for forming an electric field between the signal electrode and the upper layer signal electrode provided on the insulating film in the pixel;
The plurality of upper layer signal electrodes and the plurality of upper layer common electrodes are alternately arranged along a certain direction on the insulating film,
Between the main surface of the second substrate and the insulating film in the pixel , all of the lower layer electrodes electrically connected to the upper layer common electrode are provided in the formation region of the upper layer common electrode. a liquid crystal display device comprising a Turkey.   The liquid crystal display device according to claim 1, wherein the lower layer electrode is located between the source line and the upper layer signal electrode.   The liquid crystal display device according to claim 1, wherein the lower layer electrode is made of a translucent material.

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