JP3407865B2 - Liquid crystal display - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid crystal display device. More specifically, the present invention can be applied to, for example, a high-definition television or a high-definition monitor with a large direct-viewing display device
It relates to a liquid crystal display device.

[0002]

2. Description of the Related Art Active drive type TFT (thin film transistor) elements, PALC (plasma address liquid crystal) elements and duty drive type STN (super twisted nematic) elements are widely used as display devices. In particular, the PALC element is a switching element using plasma discharge, and its application to an ultra-large display is drawing attention. The PALC liquid crystal panel is low in cost because it does not include a semiconductor element such as a TFT, and
Attention has been focused on its potential as a large liquid crystal display device with low power consumption. The liquid crystal display device described above has characteristics such as light weight, thin shape, and low power consumption. Such a liquid crystal display device is used as a key device in the coming multimedia society in various OA and AV equipment fields. Applied development is being done. Such a liquid crystal display device has a TN display mode in which nematic liquid crystal molecules are twisted by about 90 ° in the vicinity of a pair of substrates having electrodes, or 180
The STN display mode, which is twisted more than ゜, is often used.

In a PALC display device of more than 20 type, the electric resistance values of signal lines, scanning lines, etc. and pixel electrodes are such as light transmittance, viewing angle characteristics, especially power consumption, switching speed and uniformity of display. It is greatly related to the display performance of the liquid crystal display device. When performing high-definition high-definition display (the number of scanning lines (vertical × horizontal = 1920 × 1080)), it is necessary to display the signal waveform with a delay of 10 μsec or less. In order to uniformly apply a sufficient electric field to the liquid crystal layer with a display delay of 10 μsec or less, it is essential to reduce the electric resistance of the electrodes of the color filter substrate.

The process of vacuum-depositing (sputtering) the ITO (indium tin oxide) electrode 14 on the color filter layer may be performed at around 220 ° C. because of the heat resistance of the color filter layer 16 portion including the overcoat material. The method is known in the art. In order to sufficiently reduce the sheet resistance of ITO to about 3 Ω / port for high-definition display, as shown in FIG. 1, an ITO electrode 14 having a film thickness of about 1 μm is required. The pattern etching performance deteriorates. Further, as shown in FIG. 1, the film thickness difference after the pattern etching process has a great influence on the alignment of the liquid crystal molecules 10 in the liquid crystal layer 12. Further, when the polarizing plates (not shown) provided on the pair of substrates 8 and 18 are in the crossed Nicols state, the liquid crystal molecules 1
Light leakage occurs in the region 22 where 0 exists.
Further, since the thickness of the ITO electrode 14 is large, there is a problem that the transmittance of the entire color filter substrate 18 is reduced.

[0005]

In order to solve such a problem, as shown in FIG. 2, the signal line and scanning line electrodes 24 other than the picture element electrodes may be formed of Al, Cu, or the like. Proposed. However, since these metals have a light-shielding property, the opening of the pixel area is narrowed,
There is a problem that the aperture ratio of the picture element region is lowered. Further, there is a problem in that the margin of the fine-pitch patterning process is narrow, so that the productivity is low, and in the manufacturing process, an electrolytic corrosion reaction occurs between the transparent electrodes having different electrode potentials.

In Japanese Patent Laid-Open No. 62-79421, as shown in FIG. 3, an upper electrode 32 is provided on a protective film 30 on the colored film of the color filter layer 17, and the colored film 17 is further provided.
A liquid crystal display device having a through hole 34 is disclosed. In this liquid crystal display device, since the signal applied to the lower electrode 36 is guided to the upper electrode 32 through the through hole 34, a sufficient driving voltage is applied to the liquid crystal layer 12 without causing a voltage drop due to the color filter layer. Is applied.

However, by providing the through hole 34 in the colored film 17 in the pixel area for displaying, the step of the color filter layer locally changes,
Sufficient color characteristics, that is, full-color display cannot be performed. In addition, when a large area color filter substrate is used in the through hole 34 formed by the photolithography process, the manufacturing margin of the through hole 34 is narrow, and the colored film is not completely removed in the through hole 34 portion. A contact failure between the electrode 36 and the upper electrode 32 will occur. Further, it is difficult to locally sputter the electrode on a portion having a steep inclination such as the through hole 34, which causes disconnection. In the TN mode or the STN mode,
Due to the influence of the step of the colored film of the color filter layer, display unevenness and poor color reproducibility are caused. Further, the through hole 34 affects the alignment of the liquid crystal molecules, causes the alignment failure of the liquid crystal molecules, and causes a problem that the display quality is degraded.

The present invention has been made to solve the above-mentioned problems of the prior art, and enables high-definition display.
An object is to provide a liquid crystal display device .

[0009]

A liquid crystal display device according to the present invention comprises first and second substrates, a liquid crystal layer sandwiched between the first substrate and the second substrate, and a voltage applied to the liquid crystal layer. A first substrate respectively provided on the first and second substrates for applying
And a plurality of picture element regions for displaying, the first and second voltage applying means, and
A liquid crystal display device comprising a liquid crystal region of a liquid crystal layer positioned between the first and second voltage applying means, and a non-picture element region provided between the plurality of picture element regions. The first voltage applying means has a first electrode layer formed on the surface of the first substrate and the second electrode layer formed on the first electrode layer. The first electrode layer and the second electrode layer are each formed of a transparent conductive film, and the first electrode layer is the second electrode layer.
The resistivity is lower than that of the electrode layer, an organic insulating film is formed between the first electrode layer and the second electrode layer in the plurality of pixel regions, and in the non-pixel region, The first electrode layer and the second electrode layer are electrically connected to each other, and the organic insulating film is provided in the center of each of the plurality of pixel regions.
It has an inverted conical contact hole having an inclination angle of 10 ° or less with respect to the surface of the first electrode layer, and the liquid crystal molecules are oriented in axial symmetry around the contact hole when a voltage is applied. According to the above, the above object is achieved.

The organic insulating film may have a color filter layer.

The organic insulating film further has, on the color filter layer, an overcoat layer which is transparent in the visible light region, and the overcoat layer contains a photosensitive material such as epoxy acrylate, polyglycidyl methacrylate and styrene. It may be formed from at least one of the groups of systems.

The film thickness of the first and second electrode layers is 300.
The sheet resistance values at 0Å may be about 3Ω / □ and about 4Ω / □, respectively.

The first and second electrode layers may be stripe-shaped electrodes parallel to each other, and the first electrode layer may overlap the second electrode layer.

At least one of the first and second substrates may have a convex portion on the liquid crystal layer side surface, and the convex portion may define a liquid crystal region for each of the plurality of picture element regions.

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

The operation will be described below.

The liquid crystal display device of the present invention comprises the first and second liquid crystal display devices.
It has first and second voltage applying means for applying a voltage to the liquid crystal layer, each of which is provided on the substrate, and the first voltage applying means includes a first electrode layer formed on the surface of the first substrate. ,
And a second electrode layer formed on the first electrode layer.
The first electrode layer is formed of a transparent conductive film having a resistivity lower than that of the second electrode layer, and in the plurality of pixel regions for displaying, the first electrode layer and the second electrode layer are separated from each other. Since the organic insulating film is formed between the pixel regions to be insulated, the first electrode layer and the second electrode layer are electrically connected to each other in the non-pixel region provided between the pixel regions. The electric resistance value can be significantly reduced as compared with the case where one substrate has only one electrode layer. For example, if the first substrate having the above-mentioned first voltage applying means is used in a 42-inch ultra-large high-definition liquid crystal display device, the display may be greatly delayed with respect to the signal input waveform due to the resistance of the electrode layer. It is possible to suppress the unevenness of the display speed. In addition, the formation of the first electrode layer on the first substrate has a very large margin (film thickness control, high crystallinity, and low resistance value) in the manufacturing process, and it is necessary to place it in a special gas atmosphere. Therefore, an electrode having a film thickness having a desired resistance value can be easily and accurately manufactured.

If the organic insulating film has a color filter layer, color display can be performed, and it is not necessary to separately provide an organic insulating film.

If the organic insulating film is further formed on the color filter layer by an overcoat layer formed of at least one selected from the group consisting of epoxy acrylate containing a photosensitive material, polyglycidyl methacrylate and styrene. Since the second electrode layer can be sputtered at a higher temperature, the resistance of the second electrode layer can be further reduced.

At a film thickness of 3000 Å, the first and second
The sheet resistance of the electrode layer is about 3Ω / □ and about 4Ω, respectively
If / □, for example, in a liquid crystal display device having a number of scanning lines compatible with high-definition (length × width = 1920 × 1080), the delay with respect to the input signal waveform can be set within about 10 μsec.

For example, a PALC liquid crystal display device or ST
In a liquid crystal display device such as an N (super twisted nematic) display device, in which first and second electrode layers are patterned in parallel with each other in a stripe shape,
The electrode layer and the corresponding second electrode layer overlap each other, or
If the electrode layer is formed so as to cover the first electrode layer, the first electrode layer does not intersect with the second electrode layer adjacent to the corresponding second electrode layer, and the capacitive coupling phenomenon may occur. Absent. In addition, it is not affected by signals from adjacent electrodes.

On at least one of the substrates and the liquid crystal layer side surface,
When the convex portion is provided and the liquid crystal region is defined for each of the plurality of picture element regions by the convex portion, the liquid crystal molecules of the liquid crystal layer can be oriented in axial symmetry.

If there is a region in which either the first or second voltage applying means is not formed in the central portion of the pixel region,
When a voltage is applied, the liquid crystal molecules are oriented axially symmetrically (radially or concentrically) around this region, and the axis of symmetry of the axially symmetrically oriented liquid crystal molecules can be fixed in this region, so that a wide viewing angle is possible. It is possible to provide a liquid crystal display device having excellent display quality.

If the organic insulating film has an inverted conical recess or contact hole at the center of each of the plurality of pixel regions, the liquid crystal molecules are axisymmetrically aligned around the deepest part of the recess or contact hole when a voltage is applied. However, since the alignment axis can be fixed by the recess or the contact hole, it is possible to provide a liquid crystal display device having a wide viewing angle and excellent display quality without roughness.

According to the method of manufacturing a liquid crystal display device of the present invention, the first transparent conductive film is formed on the surface of the first substrate at the temperature T1 and patterned to form the first electrode layer, and the first electrode layer is formed on the first electrode layer. In the non-pixel region by forming an organic insulating film in a region corresponding to the pixel region, forming a second transparent conductive film covering the organic insulating film at a temperature T2 lower than the temperature T1, and performing patterning. Since the second electrode layer connected to the layer is formed, the first electrode layer can be formed of a transparent conductive film having lower resistivity than the second electrode layer. This is because, as shown in FIG. 5A, for example, if the sputtering temperature of ITO is increased, the area resistance value thereof is decreased. Therefore, the electric resistance value can be significantly reduced as compared with the case where the first substrate has only one electrode layer.

If the first substrate is dry-cleaned using UV / O ₃ or vacuum ultraviolet light before forming the first and second transparent conductive films, the wettability of the substrate is increased and the space between the substrate and the conductive film is increased. It is possible to improve the adhesion of the film and prevent the conductive film from peeling off.

The liquid crystal layer contains a mixture of a liquid crystal material, a photocurable resin and a reaction initiator, and while controlling the alignment of the liquid crystal molecules in the picture element region in an axially symmetrical alignment, light is irradiated to cure the photocurable resin. By forming the axially symmetric alignment fixed layer by using the liquid crystal display device, a liquid crystal display device with improved display quality can be provided.

In order to reduce the sheet resistance of the first electrode layer as much as possible, the temperature T1 at which the first transparent conductive film is formed on the surface of the first substrate is about 400 ° C., that is, near the heat resistant temperature of the glass (substrate). It is preferable.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION The term "picture element region" will be described. The liquid crystal display device of the present invention has a plurality of picture element regions for displaying. The picture element region refers to a part (component) of the liquid crystal display device that constitutes a picture element which is the minimum unit of display.
Typically, in an active matrix type liquid crystal display device having a counter electrode and a plurality of picture element electrodes formed in a matrix and each of which is switched by an active element (TFT or the like), each picture element region is formed in each picture element region. It includes an element electrode, an area of the counter electrode facing the element electrode, and a liquid crystal area located therebetween. Further, in a simple matrix liquid crystal display device having stripe-shaped electrodes (scanning electrodes and signal electrodes) formed so as to intersect each other with a liquid crystal layer on each substrate, the pixel regions are stripe-shaped. Includes a region where the electrodes intersect and a liquid crystal region located at the intersection.

In the color display device, a color filter area is formed corresponding to each picture element area, and light passing through each color filter area is controlled by the picture element area, thereby performing color display by additive color mixing. Typically, three picture element areas, a red picture element area, a green picture element area, and a blue picture element area form one color pixel area. The color filter region refers to a region provided corresponding to the pixel region of the color filter layer, for example, a red filter region, a green filter region, and a blue filter region. The color filter region is, for example, a part of the colored layer arranged in a stripe shape. A layer including a plurality of colored layers is called a color filter layer. In the case of the stripe arrangement, a plurality of red layers, green layers and blue layers arranged cyclically are included. The color filter layer may include a colored layer or a light shielding layer (black mask) provided between the color filter regions. The color filter layer includes a plurality of colored layers of different colors, and each colored layer has a color filter region provided corresponding to the plurality of pixel regions. Further, in the present invention, a region provided for each pixel region without a colored layer is called a non-color filter region. In the present invention, the color filter layer includes a color filter area and a non-color filter area.

The correspondence relationship between the picture element region and the liquid crystal region is not limited to the case where one liquid crystal region is formed in one picture element region. However, in order to improve the display quality, the liquid crystal region is preferably formed corresponding to the picture element region. In the case of a picture element having a large aspect ratio (long picture element), a plurality of liquid crystal regions may be formed for one long picture element. The number of liquid crystal regions formed corresponding to the picture elements is preferably as small as possible as long as the axially symmetrical alignment can be stably formed.

A liquid crystal display device 90 of the present invention will be described with reference to FIGS. 4 (a) to 4 (c). Figure 4 (a)
The schematic top view of the liquid crystal display device 90 is shown. 4B and 4C are cross-sectional views of the AA portion (picture element region) and the BB portion (non-picture element region) of FIG. 4A, respectively.

The liquid crystal display device 90 of the present invention has a first substrate 52 and a second substrate 54 made of, for example, glass, and a liquid crystal layer 62 sandwiched between both substrates. First and second
The substrates 52 and 54 are provided with first and second voltage applying means for applying a voltage to the liquid crystal layer 62, respectively. The first voltage applying unit has a first electrode layer 56 formed on the surface of the first substrate 54 and a second electrode layer 58 formed thereon. The first electrode layer 56 is the second electrode layer 58.
It is formed of a transparent conductive film having a lower resistivity.

As shown in FIG. 4B, an organic insulating film 76 is formed between the first electrode layer 56 and the second electrode layer 58 in the plurality of picture element regions 70 for displaying. ing. On the other hand, as shown in FIG. 4C, the first electrode layer 56 and the second electrode layer 58 are electrically connected to each other in the non-pixel regions provided between the pixel regions.

If necessary, an alignment film (not shown) on the liquid crystal layer side of the substrate or a light-shielding layer (black mask) 78 between pixel regions may be provided.

The liquid crystal display device 90 of the present invention includes the first substrate 5
By forming a first transparent conductive film on the surface of 2 at a temperature T1 and patterning it to form a first electrode layer 56, and further forming an organic insulating film on the first electrode layer 56 and patterning it. The organic insulating film 76 is formed in a region corresponding to the pixel region. In addition, the second transparent conductive film that covers the organic insulating film 76 is formed at a temperature T2 lower than the temperature T1,
By patterning the second transparent conductive film, the second electrode layer 58 connected to the first electrode layer 56 in the non-pixel region is formed.

As the first substrate 52, a base glass substrate (contact angle; which is well washed with UV / O ₃ or vacuum ultraviolet light)
It is preferable to use 10 ° or less). Tact time (U
The V irradiation time (cleaning time) is a short time of about several minutes. If the substrate is washed, the wettability of the substrate surface will increase,
Adhesion between the substrate and the conductive film formed on the surface can be increased, and peeling of the conductive film can be prevented. An insulating film such as SiO ₂ may be previously formed on the base glass substrate.

FIG. 5A shows experimental results showing the relationship between the sputtering temperature and the sheet resistance of the transparent conductive film. As shown in FIG. 5A, the higher the sputtering temperature, the lower the electric resistance value of the transparent conductive film. Therefore,
The first substrate 52 is made of a raw glass having a high heat resistance temperature of about 400 ° C.
Vacuum sputtering is performed at a temperature of T (T1).
3 μΩ · cm)) is preferable. In order to perform high-definition display, the area resistance value of the first transparent conductive film forming the first electrode layer is preferably about 3Ω / □ or less. Then, the first electrode layer 56 is formed on the first substrate by patterning into a desired shape, for example, a stripe shape, using an etching solution (iron salt, HBr, aqua regia, etc.). The patterning process is performed by methods known in the art.

Red (R) and green (G) are formed on the first electrode layer 56.
The organic insulating film including the blue (B) color filter layer may be patterned by a method known in the art. When the organic insulating film 76 has a color filter layer, in order to raise the sputtering temperature in order to reduce the resistance of the second electrode layer 58, an overcoat layer having higher heat resistance should be formed on the color filter layer. Is preferred. When the second transparent conductive film (for example, ITO) is sputtered at a high temperature, the electric resistance value is lowered and the transmittance is improved (FIG. 5 (b)). Note that FIG. 5B shows the transmittance of the transparent conductive film using glass as a reference under a sheet resistance value of about 3 Ω / □. A second transparent conductive film made of, for example, ITO is formed by a method known in the art.
After sputtering at a temperature (T2) of about 220 ° C., the second electrode layer 58 is formed by patterning in a stripe shape, for example. The areal resistivity of the second transparent conductive film forming the second electrode layer is preferably about 6 Ω / □ or less.

The overcoat layer on the color filter layer should be formed of a photosensitive polymer such as epoxy, phenol, urethane, polyimide, polyester, rubber, diallyl phthalate, polypropylene, EPDM, melamine, ABS and vinyl chloride. Is preferred. Further, in the case of forming the overcoat layer on the color filter layer with a mixture of a photosensitizer and a polymer, as a base polymer, a negative type chloromethylated polystyrene, chloromethylated poly (α-methylstyrene), poly ( It is possible to use (chloro α-methylstyrene), polychloromethylstyrene, polyhalogenostyrene or epoxy acrylate. Further, in the positive type, it is possible to use polyglycidyl methacrylate or polymethyl methacrylate. Naphthoquinonediazide can be used as the positive-type photosensitive material, and diazonium salt-based can be used as the negative-type photosensitive material.

If the resin material for forming the color filter layer has sufficiently high heat resistance, the overcoat layer is not necessary. In such a case, the process can be shortened and the cost can be reduced.

The first electrode layer 56 and the second electrode layer 5
The pattern of 8 is striped, and the first electrode layer 56 and the second electrode layer 56
When the structure is such that the electrode layer 58 intersects,
Normal display cannot be performed. In the pixel area,
This is because the organic insulating film is sandwiched between the electrode layers, so that capacitive coupling occurs. Therefore, if the widths of the first electrode layer 56 and the second electrode layer 58 are the same and overlap, or if the second electrode layer is formed so as to cover the first electrode layer, the first electrode layer 56 The electrode layer does not overlap the second electrode layer adjacent to the corresponding second electrode layer, and the capacitive coupling phenomenon does not occur. In addition, it is not affected by signals from adjacent electrodes. In such a case, the signal waveform input to the liquid crystal layer can be accurately transmitted to each picture element and is normally displayed.

For example, in a PALC liquid crystal display device,
When performing high-definition display such as high-definition television, for example, the transparent conductive film made of ITO having a film thickness of about 3000Å preferably has an area resistance value of about 3Ω / □ (volume resistivity of about 1.3 μΩ · cm). FIG. 6 shows the results of examining the display delay (bluntness) with respect to the input signal waveform by simulation based on the capacitance between the electrode lines made of ITO having a sheet resistance value of about 3 Ω / □ and the resistance value of the electrode lines. It shows in (a).

The simulation conditions are as shown in Table 1 below.

[0050]

[Table 1]

HDTV (Number of scanning lines (vertical x horizontal = 192
0 × 1080)), the capacitance of 120 lines above and below the electrode line made of ITO is measured, and the capacitance between the lines is calculated. The resistance value of the electrode line is calculated from the length and width of the line. Based on this, the waveform rounding at the line end in the case of monochromatic display is simulated. The drive waveform is assumed to be a square wave having a rising edge and a falling edge of 2.5 μsec.

When the sheet resistance value is about 3 Ω / □, as shown in FIG.
As shown in (a), the display delay with respect to the input signal waveform was about 2 μsec, and it was found that there was no problem in display. FIG. 6B shows the deviation width (display delay) of the terminal waveform with respect to the input signal waveform at various sheet resistance values.

The above-mentioned glass / first electrode layer (IT
The two-layer electrode layer structure of (O) / organic insulating film (color filter layer) / second electrode layer (ITO) can be formed also on the TFT substrate, and the resistance can be reduced.

(Application to ASM mode) FIG. 7 (a)-
Referring to (d), the liquid crystal display device 90 of the present invention is
SM mode (Axially Symmetric Aligned Microcell Mo
de) will be explained. 7A and 7B show states when no voltage is applied, FIGS. 7C and 7D show states when a voltage is applied, and FIGS. 7A and 7C are cross-sectional views of the liquid crystal display device 90. (B) and (d) show the results of observing the upper surface with a polarization microscope in the crossed Nicols state.

The liquid crystal display device 90 includes a pair of substrates 52 and 5.
4, a liquid crystal layer 62 made up of liquid crystal molecules 61 having a negative (n type) dielectric anisotropy (Δε) is sandwiched.

In the liquid crystal display device 90, the pair of substrates 5
The vertical alignment layer 68 is formed on the surfaces of the liquid crystal layers 2 and 54 in contact with the liquid crystal layer 62, and the convex portions 74 are formed on the surface of at least one of the pair of substrates 52 and 54 on the liquid crystal layer 62 side. Due to the convex portion 74, the liquid crystal layer 62 has a thickness (din) in the picture element region of the liquid crystal layer and a thickness (dou) of the liquid crystal layer in the non-picture element region.
t) with two different thicknesses. It is preferable that din is larger than dout.

As a result, as will be described later, the liquid crystal region exhibiting the axially symmetrical alignment when a voltage is applied is defined in the region surrounded by the convex portion 74. 7A and 7C, the first and second voltage applying means for applying a voltage to the liquid crystal layer 62 are omitted.

When no voltage is applied, as shown in FIG.
The liquid crystal molecules 61 are aligned in the direction perpendicular to the substrate by the alignment regulating force of the vertical alignment layer 68. When observing a pixel region in which no voltage is applied with a crossed Nicols polarization microscope, a dark field is exhibited as shown in (b) (normally black mode). When a voltage is applied, a force is exerted on the liquid crystal molecules 62 having negative dielectric anisotropy so that the long axes of the liquid crystal molecules are aligned perpendicular to the direction of the electric field. Therefore, as shown in FIG. Tilt from the right direction (halftone display state). When the picture element region in this state is observed with a polarization microscope in the crossed Nicols state, as shown in (d), an extinction pattern is observed in a direction along about 45 ° with respect to the polarization axis.

The ASM mode liquid crystal display device as described above has an excellent viewing angle characteristic because it has a liquid crystal region which changes between vertical alignment and axially symmetric alignment depending on the voltage. Further, by using a liquid crystal material having a negative dielectric anisotropy and performing a normally black mode display in which a vertical alignment state is obtained when no voltage is applied, a high contrast display can be provided.

As will be described later, a region in which any one of the first and second voltage applying means is not formed, an inverted conical taper or a contact hole is provided at the center position of each pixel region. By fixing the axial position of the liquid crystal molecules in the axially symmetrical alignment and stabilizing the alignment of the liquid crystal molecules, the roughness of the display quality is significantly reduced.
It is desirable that the conical taper or contact hole has an inverted conical shape and has an inclination of about 10 ° or less. With such an inclination, the alignment of the liquid crystal molecules in the vicinity of the central axis of the axially symmetric alignment remains perpendicular to the substrate when a voltage is applied, and thus light leakage does not occur. In a conventional TN-aligned liquid crystal display device having a contact hole, light leakage occurs.

If the insulative black matrix is patterned in a stripe shape and is completely insulated from the adjacent signal line, the conductive color filter resin material can be used in a stripe pattern. At this time,
If the conductivity is high enough, the second pixel electrode is not needed.
If the second pixel electrode is not provided, the manufacturing process can be shortened and the cost can be reduced. However, in practice,
Color resin material of conductive color filter material,
Since the metal particles and the conductive polymer are mixed, the optical performance such as color purity and transparency is deteriorated. Further, since such impurities are eluted into the liquid crystal layer, the voltage holding ratio is lowered, and normal liquid crystal driving cannot be performed. Therefore, it is preferable to have the second electrode layer as in the liquid crystal display device of the present application.

Specific examples and comparative examples will be described below. The present invention is not limited to the examples below.

(Embodiment 1) In Embodiment 1, the above-described liquid crystal display device of the present invention is a high-definition PALC liquid crystal display device having a dot pitch and the number of scanning lines (vertical × horizontal = 1920 × 1080) compatible with high definition. The example applied to is described.

The PALC 100 shown in FIG.
The liquid crystal cell 120 including the first substrate 110 and the plasma cell substrate 130 (second substrate) are laminated.
A liquid crystal layer 136 is sandwiched between the first substrate 110 and the plasma cell substrate 130, and the first electrode layer 112 and the second electrode layer 116 are provided on the liquid crystal layer 136 side of the first substrate 110.
And an organic insulating film 114 (color filter layer) is formed.

In the plasma cell substrate 130, the ribs 14 having a plurality of gaps between the substrate 140 and the dielectric separator 138 are provided.
It has a second voltage applying means including a plurality of plasma discharge channels 144 divided by two. Plasma discharge channel 1
An ionizable gas is enclosed in 44, and plasma is generated by applying a discharge pulse voltage between the cathode 146 and the anode 146. The plurality of plasma discharge channels 144 includes signal electrodes (column electrodes) 11
The cathodes 146 and the anodes 146 function as scanning electrodes (row electrodes) and are line-sequentially scanned. Signal electrode (column electrode) 112
The potential difference between and 116 and the dielectric separator 138 drives the liquid crystal layer 136.

The PALC 100 has a plurality of picture element regions for displaying formed by a region where the plasma discharge channel 144 and the signal electrodes (column electrodes) 112 and 116 intersect, and a non-picture element region between the picture element regions. Have. In this embodiment, the size of each pixel area is about 144 μm.
× 119 μm.

In the pixel area, the first electrode layer 112 and the second electrode layer 116 are insulated by sandwiching the color filter layer 114 having an insulating property therebetween. In the non-pixel region, the first electrode layer and the second electrode layer are electrically connected.

Next, a method of manufacturing the PALC 100 of the first embodiment will be described.

On a 42-inch glass substrate 110 (contact angle of 10 ° or less) which has been previously dry-cleaned with UV / O ₃ or vacuum ultraviolet light, a first transparent film of ITO having a thickness of about 300 nm is formed at about 400 ° C. (T1). Sputter the conductive film. The sheet resistance value of the first transparent conductive film was about 3 Ω / □ (volume resistivity about 1.3 μΩ · cm). Then, the first
The transparent conductive film is patterned into a stripe shape to form the first electrode layer 112. Then, the substrate 110 is again dry-cleaned by the same method as described above.

Using a photosensitive black resin (the resin is formed by using the same material as the material of the overcoat layer on the color filter layer described above), the photomask alignment marker and the black matrix of the light shielding part ( BM) is formed. Then, the substrate 110 is again dry-cleaned by the same method as described above. Further, a color filter layer 114 is formed on the first electrode layer, the photomask alignment marker, and the black matrix (BM) of the light shielding portion,
An overcoat layer made of a polyimide resin material is formed on the color filter layer 114. A second transparent conductive film made of ITO that covers the organic insulating film including the color filter layer 114 and the overcoat layer is sputtered at a thickness of about 300 nm at about 220 ° C. (T2) lower than T1. The sheet resistance value of this second transparent conductive film is about 4Ω / □
(The volume resistivity was about 1.55 μΩ · cm). Further, the second transparent conductive film is patterned into a stripe shape, and the second electrode layer 1 connected to the first electrode layer in the non-pixel region is formed.
16 is formed.

A horizontal alignment film 118 (AL4552, made by Japan Synthetic Rubber) is formed on the surfaces of the substrates 110 and 130 on the liquid crystal layer 136 side. After applying the alignment film, the alignment treatment is performed by rubbing or the like so as to obtain a desired twist angle. Further, spacers having a height of about 6 μm are formed on the horizontal alignment layer 118 by using plastic beads.
The liquid crystal cell 120 manufactured as described above is bonded to a plasma cell substrate 130 manufactured by a predetermined method, and a liquid crystal material having a positive dielectric anisotropy (Δε = 1. 9, Δn = 0.067, cell gap 6μ
(Twist angle peculiar to liquid crystal material was set so that the twist would be 90 ° in m), followed by heating and quenching.

When a voltage was applied to confirm lighting of the entire surface, it was observed that the display area uniformly changed from white to black under the polarizing plate crossed Nicols. The display delay with respect to the signal input waveform at this time is within an allowable range of about 10 μsec or less, and good display quality could be obtained in high definition display such as high definition display.

(Embodiment 2) The 42-inch PALC 200 of Embodiment 2 shown in FIG.
A liquid crystal region is defined for each of the plurality of picture element regions and liquid crystal molecules are axially symmetrically aligned.

The PALC 200 has a structure in which a liquid crystal cell 220 including a first substrate 110 and a plasma cell substrate 130 (second substrate) are laminated. PAL of FIG. 8 (a)
It differs from C100 in that the PALC 200 has the convex portion 205 and the vertical alignment film 218.

The convex portion 205 of the PALC 200 is a grid-like wall having a height of about 3 μm formed by patterning a photosensitive resin material. The second transparent conductive film may be sputtered on the substrate 110 after forming the grid-shaped convex portions 205 to form the second electrode layer 116 included in the first voltage applying unit. Spacers (columns (not shown) serving as a cell thickness holding material) having a height of about 3 μm were formed at desired positions on the convex portions 205. Further, JALS-204 (manufactured by Japan Synthetic Rubber) is spin-coated, and the vertical alignment layer 218 (JALS-) is formed on the liquid crystal layer 136 side surface of both substrates 110 and 130.
204, made by Japan Synthetic Rubber).

In the manufactured liquid crystal cell 220, a liquid crystal material having a negative dielectric anisotropy (Δε = −4, Δn = 0.08, twist of 90 ° at a cell gap of 6 μm, which is peculiar to the liquid crystal material, is used. The angle was set), and a precursor, which was a mixture of a photopolymerization initiator and a photopolymerization monomer, was injected.

Photosensitive acrylic, methacrylate, polyimide, or rubber materials may be used for the protrusions 205 and the spacers. Has photosensitivity, writing pressure (400g / m
Any material may be used as long as it has a strength such that the protrusions and the spacers are not destroyed by a pressure of about m ² ).

The liquid crystal molecules contained in the liquid crystal layer 136 are ASM
Axisymmetrically oriented so that it is oriented
40V was applied to the liquid crystal cell 220. When the axial centering alignment centering voltage was continuously applied, one axially symmetric region (mono domain) was formed for each pixel region.

The in-plane retardation is about 43 nm and the retardation in the normal direction is about 1 on both sides of the liquid crystal cell 220.
A 91-nm biaxial retardation plate (not shown) was provided, and deflection plates were arranged on both sides of the retardation plate so as to be in a crossed Nicols state, to manufacture a liquid crystal display device.

When a voltage is applied to confirm full lighting, it is observed that the polarizing plate is in the crossed Nicols state and the display area changes from white to black uniformly, and the switching display delay with respect to the input waveform is about 10 μm. It was less than a second, and there was no problem at all in the high-definition scanning line number (vertical × horizontal = 1920 × 1080) display.

The electro-optical characteristic (voltage-transmittance characteristic) of the PALC200 is shown in FIG. 9 (a). As is clear from FIG. 9A, according to PALC200, the transmittance in the OFF state was low, and a good voltage-transmittance ratio was obtained.

Further, FIG. 9B shows the viewing angle characteristic of contrast by PALC200. In FIG. 9B, ψ is an azimuth angle (angle within the display surface), θ is a viewing angle (tilt angle from the normal to the display surface), and hatching indicates a region where the contrast ratio is 10: 1 or more. As is clear from FIG. 9B, according to PALC200, a high contrast ratio was obtained in a wide viewing angle range, and a substantially circular viewing angle characteristic could be obtained.

(Example 3) A top view of a liquid crystal cell included in the 42-inch PALC of Example 3 is shown in FIG.
FIG. 10 is a sectional view (picture element region) taken along line AA in FIG.
It shows in (b).

The PALC of Example 3 has the first electrode layer and the second electrode layer.
It is different from the PALC 200 of the second embodiment in that the contact hole 326 for connecting to the electrode layer is provided in the central portion of the color filter layer 322 of each pixel region 70.

The contact hole 326 is formed to have an inclination angle α of about 10 ° or less.

While applying a voltage to the PALC of Example 3, the pixel region was observed in a transmission mode of a polarizing microscope (crossed Nicols state). Shortly after the voltage was started, the ratio of the liquid crystal molecules in which the central axis of the alignment of the liquid crystal molecules aligned in the axially symmetrical manner was located in the substantially central portion of the pixel region was about 10% of all the liquid crystal molecules. By continuing to apply the voltage, as shown in FIG. 7C, the liquid crystal molecules are aligned in axial symmetry in each pixel region, and the axially symmetric alignment central axis is located in the substantially central portion of the pixel region. It was observed to form at corresponding positions. That is, it was confirmed that the alignment axes of the liquid crystal molecules were concentrated at the positions of the contact holes 326.

Comparative Example 1 In Comparative Example 1, high-definition PALC was used.
Number of high-definition scanning lines of liquid crystal display (vertical x horizontal = 192
An example in which high-definition display is performed by a device having an ITO electrode structure as shown in FIG. 1 having a conventional electrical resistance value for VGA, which corresponds to 0 × 1080) will be described.

The color filter substrate included in the liquid crystal display device of Comparative Example 1 had transparent electrodes formed of ITO and having a film thickness of 300 nm and a sheet resistance value of 6 Ω / □ in the form of stripes. In Comparative Example 1, the color filter substrate described above was bonded to the 42-inch plasma cell substrate similar to that of Example 1, to fabricate a TN liquid crystal cell. When the display switching was confirmed, the display was non-uniform, a sufficient voltage was not applied to the liquid crystal layer, and saturation was not obtained due to the voltage-transmittance (VT) characteristic. Further, the display delay was 10 μs or more with respect to the signal input waveform.

Comparative Example 2 In the device of Comparative Example 2, as shown in FIG. 11, the first electrode layer 56 'and the second electrode layer 58' intersect in the non-pixel region B. Note that FIG.
[FIG. 3] is a partially enlarged top view of the non-pixel region B of the liquid crystal display device of Comparative Example 2.

When the liquid crystal driving driver was TAB-attached to the second electrode layer wiring, a different first electrode layer which was not corresponding was connected, and the display was not normal due to capacitive coupling.

Comparative Example 3 In Comparative Example 3, the high-definition PAL is used.
C In the manufacturing process of the liquid crystal display device, the color filter substrate is formed by the conventional method (20% NaO) before forming the first and second electrode layers (ITO electrodes) and the color filter layer.
20 minutes with Haq + US (ultrasonic), pure water rinse, IPA
Washing was performed by washing and drying (10 minutes). The contact angle of each layer was 10 ° or more, and structural defects and film peeling occurred in the step of patterning the second electrode layer.

[0092]

As described above, according to the present invention, a high-definition display liquid crystal having a low electric resistance value and a high transmittance can be obtained.
A display device can be provided. The present invention is an HDTV
It is preferably used for a liquid crystal display device compatible with high definition display such as XGA and XGA.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a conventional liquid crystal display device.

FIG. 2 is a cross-sectional view showing a conventional liquid crystal display device.

FIG. 3 is a cross-sectional view showing a conventional liquid crystal display device.

4A to 4C are diagrams showing a liquid crystal display device of the present invention.

FIG. 5A is a graph showing the relationship between the sputtering temperature and the sheet resistivity of the transparent conductive film, and FIG. 5B is a graph showing the relationship between the sputtering temperature and the transmittance of the transparent conductive film.

6A is a graph showing a simulation result of a display delay with respect to an input signal waveform, and FIG. 6B is a graph showing a relationship between a sheet resistance value and a display delay.

7 (a) and 7 (c) are cross-sectional views of a liquid crystal display device according to the present invention, and FIGS. 7 (b) and 7 (d) are views showing the results of observing the upper surface with a polarization microscope in a crossed Nicols state.

8A and 8B are cross-sectional views of a liquid crystal display device according to an embodiment of the present invention.

9A is an electro-optical characteristic (voltage-transmittance characteristic) of the liquid crystal display device of the present invention, and FIG. 9B is a viewing angle characteristic of contrast.

10A and 10B are diagrams showing a liquid crystal display device according to an embodiment of the present invention.

FIG. 11 is a partial top view of a liquid crystal display device of a comparative example.

[Explanation of symbols]

54 second substrate 56 First electrode layer 58 Second electrode layer 62 Liquid crystal layer 70 picture element area 78 Light-shielding layer 90 Liquid crystal display

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-1-99028 (JP, A) JP-A-4-342231 (JP, A) JP-A-7-84277 (JP, A) JP-A-5- 313209 (JP, A) JP-A-7-43719 (JP, A) JP-A-8-292423 (JP, A) JP-A-9-90389 (JP, A) JP-A-8-234218 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02F 1/1343 G02F 1/1333 G02F 1/1337

Claims (6)

(57) [Claims] 1. A first and second substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, and the first and second substrates for applying a voltage to the liquid crystal layer. A plurality of picture element regions for displaying, and a first and a second voltage applying means respectively provided in the first and second voltage applying means.
And a liquid crystal region of a liquid crystal layer located between the first and second voltage applying units, and a non-picture element region is provided between the plurality of picture element regions. And a first electrode layer formed on the surface of the first substrate, and a second electrode layer formed on the first electrode layer. The first electrode layer and the second electrode layer are each formed of a transparent conductive film, and the first electrode layer has a lower resistivity than the second electrode layer. An organic insulating film is formed between the first electrode layer and the second electrode layer in the pixel region, and the first electrode layer and the second electrode layer are electrically connected to each other in the non-pixel region. are connected to, organic insulating film, the respective central portion of the pixel region of the plurality of inclination angle of 10 ° below the plane of the first electrode layer as a reference Has an inverted conical contact hole becomes, the liquid crystal molecules when a voltage is applied axially symmetrically oriented around the contact holes, a liquid crystal display device. 2. The liquid crystal display device according to claim 1, wherein the organic insulating film has a color filter layer. 3. The organic insulating film further has, on the color filter layer, an overcoat layer transparent in a visible light region, and the overcoat layer contains a photosensitive material such as epoxy acrylate and polyglycidyl methacrylate. The liquid crystal display device according to claim 2, wherein the liquid crystal display device is formed of at least one of the group consisting of: 4. The film thickness of each of the first and second electrode layers is 30.
4. The liquid crystal display device according to claim 1, wherein the sheet resistance values at 00Å are about 3Ω / □ and about 4Ω / □, respectively. 5. The first and second electrode layers are stripe-shaped electrodes parallel to each other, and the first electrode layer is the second electrode layer.
The liquid crystal display device according to claim 1, wherein the liquid crystal display device overlaps with the electrode layer. 6. At least one of the first and second substrates has a convex portion on the liquid crystal layer side surface, and the convex portion defines a liquid crystal region for each of the plurality of picture element regions. The liquid crystal display device according to claim 1.