JPH095701A - Liquid crystal display - Google Patents

Abstract

PURPOSE: To prevent the occurrence of the unequal display of a liquid crystal display device of a transverse electric field driving type by specifying the angle formed by the liquid crystal molecules held between a pixel electrode substrate and a non-pixel electrode substrate and the boundaries of the substrates and the thickness of a liquid crystal layer. CONSTITUTION: Common electrodes 1 are patterned on the one transparent glass substrate 7 of a liquid crystal element consisting of electrodes, driving means, oriented films and polarizing plates and signal electrodes 3 and the pixel electrodes 4 are formed on gate insulating films 2 formed the patterned electrodes. Insulating protective films and orientation control films 5 are applied and are subjected to orientation treatments. The liquid crystal layer is held between the transparent substrate (pixel electrode substrate) 7 and the other transparent substrate (non-pixel electrode substrate) 7 not formed with the electrodes. The pixel electrodes 4 impress the electric fields parallel with the substrates on the liquid crystal layer. The angle (pretilt angle) formed by the bar-shaped liquid crystal molecules 6 of the liquid crystal layer and the boundaries of the substrates 7 is specified to <=5 to 30 deg. and the thickness of the liquid crystal layer is specified to 4 to 10μm. As a result, the need for the selectivity of the refractive index anisotropy of the liquid crystals is eliminated and the thickness of the liquid crystal layer is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a horizontal electric field type liquid crystal display device which can be driven at a low voltage even when n is large and a gap of a liquid crystal layer is large.

[0002]

2. Description of the Related Art A conventional liquid crystal display device is typified by a twisted nematic (TN) display system which operates by setting a direction of an electric field applied to liquid crystal in a direction substantially perpendicular to a substrate interface. On the other hand, as a method (horizontal electric field method) for making the direction of the electric field applied to the liquid crystal substantially parallel to the substrate interface, for example, a method using comb-teeth electrodes is disclosed in Japanese Patent Publication No. 63-21907 and Japanese Patent Publication No.
-505247. This lateral electric field method is attracting attention because of its advantages such as a wider viewing angle than the conventional TN method. A description of the pretilt angle as in the present invention is found in Japanese Patent Publication No. H05-505247, but there is no description of the detailed effects thereof.

[0003]

The physical properties of liquid crystals are related to characteristics such as driving voltage, response time, and transmittance, and are related to each other in some way. In order to obtain the same characteristics as TN in the case of displaying the in-plane switching mode as a birefringence type, in order to obtain characteristics equivalent to TN, retardation (R) = Δnd (Δn is a refractive index anisotropy of liquid crystal, d is a liquid crystal layer). Thickness of about 1/4 wavelength (eg 0.32 μm).
Since the minimum value of Δn of a practical liquid crystal commercially available at present is about 0.08, the value of d is close to 4 μm.
This thickness is a very small value as compared with many liquid crystal elements on the market. In general, when the thickness is reduced, display unevenness due to non-uniformity in thickness is remarkable. It will inevitably become a major obstacle to commercialization.

An object of the present invention is to provide a horizontal electric field type liquid crystal display device having no display unevenness.

[0005]

In order to achieve the above object, the present invention uses the following means.

[Means 1] In a liquid crystal element including an electrode, a driving unit, an alignment film, and a polarizing plate, a pixel electrode is formed on one substrate (pixel electrode substrate) and the other substrate (non-pixel substrate). In the lateral electric field drive type liquid crystal display device in which no electrode is formed on the electrode substrate) and the pixel electrode applies an electric field mainly to the liquid crystal layer in parallel to the substrate surface, the pixel electrode substrate and the non-pixel The angle (pretilt angle) formed by the liquid crystal molecules sandwiched between the electrode substrate and the substrate is 5
A liquid crystal display device having a thickness of not less than 30 degrees and not more than 30 degrees, and a thickness (gap) of the liquid crystal layer exceeding 4 μm and not more than 10 μm.

[Means 2] In the means 1, the alignment films formed on the pixel electrode substrate and the non-pixel electrode substrate are rubbed, combined so that the rubbing directions are substantially parallel to each other, and polarized on the outside of each substrate. A liquid crystal display device in which a plate is provided and the polarization axes of the polarizing plates are orthogonal to each other to provide a birefringent display mode.

[Means 3] A liquid crystal display device according to the means 1 or 2, wherein an active element is formed on the pixel electrode substrate.

[Means 4] A liquid crystal display device according to the means 1 or 2, wherein RGB color filters are formed on the non-pixel electrode substrate.

[Means 5] A liquid crystal display device according to the means 1 or 2, wherein the pixel electrode substrate is formed in a comb shape.

[0011]

In general, the refractive index anisotropy Δn of a liquid crystal molecule having no pretilt angle θ is represented by Δn = | _{n‖ −n⊥} |. However, the refractive index anisotropy (Δ
n ′) is

[0012]

[Equation 1] Δn ′ = √ [n _‖ ² cos ² θ + n _⊥ ² sin ² θ] −n _⊥ (Expression 1) and apparently Δn> Δn ′. If the same retardation (R) is used, R = Δnd = Δn′d ′
Therefore, d <d '(d' is the apparent thickness of the liquid crystal layer). That is, when the pretilt angle exceeds a certain value, the refractive index anisotropy becomes small and the thickness of the liquid crystal layer can be made large. Recently, if the liquid crystal layer is thickened,
It is empirically known that the uniformity of the thickness d is improved.

(1) Principle of operation of lateral electric field system First, the principle of operation of the lateral electric field system, which is an essential component of the present invention, will be described. FIG. 2 shows the definition of the angle φ _LC formed by the liquid crystal molecule major axis (optical axis) direction 10 near the interface with respect to the electric field direction 9 and the angle φ _P formed by the polarization transmission axis 11 of the polarizing plate. Since there are a pair of the polarizing plate and the liquid crystal interface above and below, respectively, they are denoted as φ _P1 , φ _P2 , φ _LC1 , and φ _LC2 as necessary. 2 corresponds to the front view of FIG. 1 described later.

1 (a) and 1 (b) are side sectional views showing the operation of the liquid crystal in the liquid crystal panel of the present invention, and FIGS. 1 (c) and 1 (d) are front views thereof. In FIG. 1, the thin film transistor element portion is omitted and a part of the wiring electrode structure is shown. Further, although the display device of the present invention is composed of a plurality of pixels, only a part within one pixel is shown here. FIG. 1A shows a cross section of the cell when no voltage is applied, and FIG. 1C shows a front view at that time. Linear electrodes 1 and 4 are formed inside a pair of transparent substrates, and a protective film and an orientation control film 5 are applied and oriented thereon. In this figure, the protective film and the orientation control film are integrally drawn, but one material may be used in common or two materials may be laminated. A liquid crystal composition is sandwiched between them. The rod-shaped liquid crystal molecules 6 are aligned such that they have a slight angle with respect to the longitudinal direction of the electrodes 1 and 4 (front view of FIG. 1C) when no electric field is applied, that is, 45 ° ≦ | φ _LC | <90 °. Has been done. In FIG. 1 and FIG. 2, the long axis alignment 0 (rubbing) direction 10 of liquid crystal molecules on the interface is indicated by an arrow. As a desirable example, the alignment directions of liquid crystal molecules on the upper and lower interfaces are parallel, that is, φ _LC1 = φ _LC2 (= φ _LC ). The dielectric anisotropy of the liquid crystal composition is assumed to be positive.

Here, when different electric potentials are applied to the pixel electrode 4 and the common electrode 1 and a potential difference is applied between them to apply the electric field 9 to the liquid crystal composition layer, the dielectric anisotropy and electric field of the liquid crystal composition are applied. As shown in FIGS. 1 (b) and 1 (d), the liquid crystal molecules react with each other due to the interaction with and change their direction to the direction of the electric field. At this time, the brightness changes due to the interaction between the refractive index anisotropy of the liquid crystal composition layer and the polarizing plate.

(2) Control of Pretilt Angle The pretilt angle is achieved by the alignment film formed on the surface of the substrate. Specifically, the SiO oblique vapor deposition method and the grating method are known as the inorganic alignment film, and the rubbing method of an organic thin film such as a polyimide thin film (liquid crystal device handbook, published by Nikkan Kogyo Shimbun, p240) is known as the organic alignment film. Therefore, the object of the present invention can be achieved by either method. However, from the viewpoint of productivity, the rubbing method of a polyimide thin film is preferable.

[0017]

EXAMPLES The present invention will be specifically described with reference to examples.

[Example 1] The substrate has a thickness of 1.1 mm.
Transparent glass substrate (200 × 270m
Use 2 m). First, a thin film transistor was formed on one of these substrates by the following procedure. The matrix element composed of the thin film transistors and the wiring electrodes may be any as long as a lateral electric field can be applied, and the manufacturing method thereof is not related to the essence of the present invention, and therefore the description will be simplified. Further, the description here regarding the manufacturing method of the matrix element is an example, and the present invention is not limited to this.

This embodiment will be described with reference to FIGS. 7, 8 and 9 which schematically show the cross-sectional view taken along the line CC ′ of FIG. 3 showing the structure of one pixel.

A chromium film was formed on one of the transparent glass substrates 7 by the sputtering method, and then the gate electrode 12 and the common electrode 1 were patterned by the photolithography method (FIG. 7A). After that, the gate insulating film 2 made of silicon nitride (SiN) is formed thereon by the CVD method (FIG. 7 (b)), and the CVD method is also formed thereon.
A- whose surface layer is an n-type amorphous silicon (a-Si) film
Si13 was produced (FIG. 7 (c)). A signal electrode (drain electrode) 3 and a pixel electrode 4 made of chromium were formed by a sputtering method or a photolithography method so as to cover a part of the a-Si 13 and form a thin film transistor (FIG. 7).
(D)). An insulating protective film 5 made of SiN was formed thereon (FIG. 8E). Thereafter, a light-shielding layer 22 and a pigment color filter 23c are formed thereon, and a surface planarizing resin 23b is spin-coated thereon (FIG. 8).
(F)). As the light-shielding layer 22, an epoxy resin containing 1% by weight of carbon fine particles (MONARCH 800, particle diameter 16 nm) manufactured by Cabot Corporation was used. As the color-developing pigment of the color filter, CR-6101, CG-5101 and CB-6101 manufactured by Fuji Hunt Co. were used for the three primary colors of red, green and blue, respectively. It was applied by spin coating, prebaked at 85 ° C., exposed and developed, and finally post-baked at 200 ° C. to form a film-like color filter. In this example, a pigment was used as the color-developing layer, but according to the present invention, since it is not necessary to heat to a high temperature in the subsequent alignment film forming process, a dye-type coloring agent having a low heat resistance and a brighter color is used. You may use it. Further, as the material for the light-shielding layer, in this embodiment, a material such as carbon black fine particles which may be a pollution source that lowers the specific resistance of the liquid crystal is used.
There is no problem because the lateral electric field method itself is resistant to contamination. Rather, since the carbon black fine particles have an extremely high light-shielding rate, higher image quality can be realized. Of course, there is no problem even if other insulating light-shielding agents such as pigments and dyes other than carbon black fine particles are used. Further, an epoxy resin was used as the resin for flattening the surface, but the resin is not limited to this material. Next, a solution 24a of RN-1046 (manufactured by Nissan Kagaku), which is a solvent-soluble polyimide precursor.
Was applied by spin coating (FIG. 8 (g)). In this embodiment, the spin coating method is adopted as the coating method,
It is not limited to this as long as it is a method capable of applying a uniform film thickness such as various printing methods such as letterpress printing, offset printing, screen printing, roll coating method, dip method and the like.
Then, this solution was heated to 200 ° C. and left for 30 minutes to remove the solvent. Thus, a dense polyimide alignment film 24b was obtained (FIG. 8 (h)). Next, with a buff cloth (24 (d)) attached to the rubbing roller (24 (c)),
This surface was subjected to a rubbing treatment to impart liquid crystal aligning ability to the surface of the alignment film (FIG. 9 (i)). In the present embodiment, the rubbing method was adopted as the method of imparting the orientation ability, but other methods such as SiO oblique vapor deposition can also be used. Next, a substrate on the opposite side in which the alignment film surface is provided with liquid crystal aligning ability by the same material and process, and the surface 24 having each liquid crystal molecule aligning ability.
(E) The cells were assembled with the spacers made of polymer beads and the sealing agent 27 in the peripheral portion interposed therebetween, with the cells facing each other (FIG. 9 (j)). The liquid crystal composition 6 was injected into this cell in a vacuum and sealed with a sealant 28 made of an ultraviolet curable resin (FIG. 9 (k)). After that, drive circuit to this cell,
Connects a polarizing plate, a backlight, etc. to make a module, 1
A 0.4 inch size liquid crystal display device was obtained.

Next, the structure of the liquid crystal display device obtained by the above process will be described in more detail.

The rubbing directions on the upper and lower interfaces are substantially parallel to each other, and the angle with the direction of the applied electric field is 88 degrees (φ _LC1
= Φ _LC2 = 88 °). The dielectric anisotropy Δε of the nematic liquid crystal composition sandwiched between these substrates is positive and its value is 9.0 (1 kHz, 20 ° C.).
Is 0.0819 (n _‖ = 1.5603, n _⊥ = 1.478
4, but with a wavelength of 589 nm and 20 ° C.). With respect to the thickness (gap) d of the liquid crystal layer, spherical polymer beads were dispersed and sandwiched between the substrates, and eight liquid crystal display devices each having a thickness of 3 μm to 10 μm and 1 μm each were manufactured in a state where the liquid crystal was enclosed. Further, the same alignment film material was formed on the glass substrate by the same process, and the pretilt angle of the liquid crystal molecule major axis was measured by the crystal rotation method. The retardation (R) in the horizontal electric field type liquid crystal display device is 0.28 to 0.36 μ.
m is desirable, but R is 0.32 μm in the middle
From the calculation of Equation 1, Δn ′ becomes 0.0743,
d'is 4.3 μm.

Next, two polarizing plates [G122 manufactured by Nitto Denko Corporation]
0DU], and the polarization transmission axis of one polarizing plate is slightly smaller than the rubbing direction, that is, φ _P1 = 80 °.
(That is, | φ _LC1 −φ _P1 | = 8 °), and the other is orthogonal, that is, φ _P2 = −12 °. As a result, as the voltage V _LC applied to the pixel was gradually increased from zero, the brightness decreased and reached the minimum value (FIG. 4). In this embodiment, a low voltage (V _OFF ) causes a dark state, and a high voltage (V _OFF ).
_{It has a} normally closed characteristic that is bright when turned on.

The structures of the thin film transistor and various electrodes are shown in FIG. 3 and will be described in detail. FIG. 3A is a front view seen from a direction perpendicular to the substrate surface, and FIGS. 3B and 3C are side sectional views. The thin film transistor element 14 is composed of a pixel electrode (source electrode) 4, a signal electrode (drain electrode) 3, a scan electrode (gate electrode) 12, and amorphous silicon 13. The common electrode 1 and the scan electrode 12, and the signal electrode 3 and the pixel electrode 4 are formed by patterning the same metal layer. The capacitive element 16 is formed as a structure in which the insulating protective film 2 is sandwiched between the pixel electrode 4 and the common electrode 1 in a region (indicated by a dotted line in FIG. 3) connecting the two common electrodes 1. The pixel electrode is arranged between two common electrodes 1 in the front view (FIG. 3A). The pixel pitch is 69 μm in the horizontal direction (that is, between signal wiring electrodes) and 207 μm in the vertical direction (that is, between scanning wiring electrodes). The electrode width is
The scanning electrode, the signal electrode, and the common electrode wiring portion (the portion extending in parallel to the scanning wiring electrode (horizontal direction in FIG. 3)), which are wiring electrodes extending over a plurality of pixels, were widened to avoid line defects. Each width is 10 μm. On the other hand, in order to improve the aperture ratio, the widths of the pixel electrode formed independently for each pixel and the part of the common electrode extending in the longitudinal direction of the signal wiring electrode are slightly narrowed to 5 μm and 8 μm, respectively. By narrowing the width of these electrodes, the possibility of disconnection due to the inclusion of foreign matter or the like increases, but in this case, a partial defect of one pixel does not lead to a line defect. In addition, the common electrode and the signal electrode are slightly separated via an insulating film to achieve the highest possible aperture ratio.
(1 μm) stacked. As a result, the black matrix in the direction parallel to the signal wiring becomes unnecessary. Therefore, as shown in FIG. 3C, a black matrix structure that shields light only in the scanning wiring electrode direction is adopted. Thus, the gap between the common electrode and the pixel electrode was 20 μm, the length of the opening in the longitudinal direction was 157 μm, and a high aperture ratio of 44.0% was obtained. The number of pixels is 640 × 3 signal wiring electrodes and 48
The number of wiring electrodes was set to 640 × 3 × 480.
A panel portion composed of a plurality of pixels is shown in FIGS. In FIG. 5, the black matrix is omitted, and in FIG. 6, the black matrix is used to block light.

Next, the circuit configuration and drive waveform will be described. A scanning electrode driving circuit 18 and a signal electrode driving circuit 1 are provided in each scanning wiring 12 and each signal wiring 3, respectively.
9 was connected. The common electrode driving circuit 20 was also connected to the common electrode 1 (FIG. 10). A signal waveform having information is applied to the signal electrode 3, and a scanning waveform is applied to the scanning electrode 12 in synchronization with the signal waveform. An information signal is transmitted from the signal electrode 3 to the pixel electrode 4 via the thin film transistor 14, and a voltage is applied to the liquid crystal portion between the signal electrode 3 and the common electrode 1. FIG. 11 shows a specific example of the drive voltage waveform. The amplitudes in this embodiment are V _D-CENTER = 14.0, V _GH = 28.0, V _GL = 0, V _DH
= 15.1, V _DL = 12.9, V _CH = 20, 4, V _CL =
4.39, and as a result, the jump voltages ΔV _GS (+) and ΔV _GS (-) due to the parasitic capacitance between the gate electrode and the source electrode, the voltage V _S applied to the pixel electrode, and the voltage V _LC applied to the liquid crystal are It looks like the table below. The unit of voltage will be all volts hereinafter.

[0026]

[Table 1]

V _ON and V _OFF shown in FIG. 4 are 9.1 respectively.
It became 6 volts and 6.85 volts. As the effect of increasing the pretilt angle, the nonuniformity of the alignment is eliminated and the uniformity of the display is improved. When the display performance was measured with a photoelectric photometer, as shown in FIG. 15, the transmittance at V _ON was almost uniform at 35% between the thickness of the liquid crystal layer of 3 μm and 10 μm.
Thus, no display unevenness due to the difference in the thickness of the liquid crystal layer was observed, and a highly uniform display was obtained.

Example 2 Instead of the polyimide alignment film RN-1046 of Example 1, 8T silane (produced by Shin-Etsu Chemical Co., Ltd.) was used instead of 2 parts and PIQ (produced by Hitachi Chemical) 98 parts. A liquid crystal display device was manufactured in the same manner as in Example 1. This pretilt angle was 30 degrees. From the calculation of Equation 1, Δn ′ is 0.0635 and d ′ is 5.0 μm. When evaluated in the same manner as in Example 1, the transmittance increased to 40% as the pretilt angle increased as shown in FIG. 15, but the variation due to the thickness of the liquid crystal layer was small. No display irregularity was observed, and a highly uniform display was obtained.

[Example 3] A liquid crystal display device was produced in the same manner as in Example 1 except that LQ-1800 (manufactured by Hitachi Chemical Co., Ltd.) was used instead of RN-1046 of the polyimide alignment film of Example 1. . This pretilt angle was 10 degrees.
From the calculation of the equation 1, Δn ′ is 0.0795 and d ′ is 4.0 μm. When evaluated in the same manner as in Example 1, the transmittance decreased to 30% due to the small pretilt angle as shown in FIG. 15, but the variation due to the thickness of the liquid crystal layer was small. No display unevenness due to the difference in the thickness of the liquid crystal layer was observed, and a highly uniform display was obtained.

[Example 4] A liquid crystal display device was produced in the same manner as in Example 1 except that RN-1046 (manufactured by Nissan Kagaku Co., Ltd.) was used in place of RN-1046 of the polyimide alignment film of Example 1. did. This pretilt angle was 6 degrees. From the calculation of Equation 1, Δn 'is 0.0821, and d'is 3.
It becomes 9 μm. When evaluated in the same manner as in Example 1, as shown in FIG. 15, the transmittance was reduced to 26% due to the small pretilt angle, but the variation due to the thickness of the liquid crystal layer was small. No display unevenness due to the difference in the thickness of the liquid crystal layer was observed, and a highly uniform display was obtained.

Example 5 A polyimide alignment film was used as in Example 1, and a color filter was formed on the counter substrate side in this example. FIG. 12 shows a schematic cross-sectional view of the liquid crystal display device of this example. A color filter 23c having a plurality of colors is laminated on the counter substrate 7, and boundaries of the plurality of colors are arranged right above the light shielding layer 22 on the matrix substrate. Since the width of the light-shielding portion is 50 μm, which is much wider than the alignment accuracy of 3 to 10 μm between the substrates of a general liquid crystal panel assembling apparatus, it can be assembled very easily. In addition, the color filter of this embodiment is a positive type film (FUJICHROME, PROVIA, 100DAYLIGHT, RDP II1 manufactured by Fuji Photo Film Co., Ltd.
In 35), a pattern of a plurality of colors was formed by single light irradiation. The film has a plurality of color-developing layers between two protective films in advance. Therefore, if light is irradiated through a photomask corresponding to a color pattern required for a liquid crystal display device, the color filter can be irradiated by one light irradiation. can get. After this color filter was adhered onto the counter substrate at room temperature while applying pressure with an epoxy adhesive,
A liquid crystal display device was produced in the same manner as in. When the characteristics of this device were evaluated, the same results as in Example 1 were obtained, no display color unevenness due to the difference in the thickness of the liquid crystal layer was observed, and a highly uniform display was obtained. The color tone of the color filter produced from such a positive type film was very vivid, and the color of the liquid crystal display device of the present invention using it was also vivid.

In this embodiment, a color-forming layer sandwiched between protective films was used and bonded to a glass substrate after forming a color filter pattern. However, even if the color-forming layer is formed on the glass substrate from the beginning. Good. Further, although it is preferable to perform the light exposure once in terms of manufacturing cost, it may be performed plural times.

[Example 6] A color filter was prepared by the same process as in Example 5, using a polyimide alignment film as in Example 1, and using a positive type film EKTACHROME DYNA 100 manufactured by Kodak in this example. did. In addition, the light shielding layer was provided in the color filter pattern, and the light shielding layer was not formed in the active element. FIG. 14 shows the arrangement of the light shielding layers in the color filter of this embodiment. FIG. 14A shows a side cross section and FIG. 14B shows a pattern when viewed from the front.

A liquid crystal display device was manufactured in the same manner as in Example 1,
When the characteristics were evaluated, the same results as in Example 1 were obtained,
No display color unevenness due to the difference in the thickness of the liquid crystal layer was observed, and a highly uniform display was obtained. As in Example 4, the color tone of the color filter produced from such a positive type film was very vivid, and the color of the liquid crystal display device of this example using this was also vivid.

Comparative Example 1 A liquid crystal display device was manufactured in the same manner as in Example 1 except that PIQ (manufactured by Hitachi Chemical Co., Ltd.) was used instead of RN-1046 of the polyimide alignment film of Example 1. This pretilt angle was 1.0 degree. From the calculation of Equation 1, Δn ′ is 0.0865 and d ′ is 3.7 μm.
Becomes When evaluated in the same manner as in Example 1, FIG.
As shown in 5, the pretilt angle was so small that the transmittance changed from 7% to 24.5%, and the change amount depending on the thickness of the liquid crystal layer was large. The display color unevenness was conspicuous due to the variation in the thickness difference of the liquid crystal layer.

[Comparative Example 2] A liquid crystal display device was produced in the same manner as in Example 1 except that RN-1046 (manufactured by Nissan Kagaku Co., Ltd.) was used in place of RN-1046 of the polyimide alignment film of Example 1. did. This pretilt angle was 4 degrees. From the calculation of Equation 1, Δn ′ is 0.0842 and d ′ is 3.
8 μm. When evaluated in the same manner as in Example 1, the transmittance changed from 14% to 26% because the pretilt angle was very small as shown in FIG. 15, and the amount of change due to the thickness of the liquid crystal layer was large. The display color unevenness was conspicuous due to the variation in the thickness difference of the liquid crystal layer.

According to Examples 1 to 4 described above, in the horizontal electric field type liquid crystal display device, by adopting a large pretilt angle, the margin with respect to the thickness of the liquid crystal layer is increased, and the liquid crystal display device with high image quality without display unevenness is obtained. was gotten.

[0038]

According to the present invention, by introducing a high pretilt angle into a horizontal electric field type liquid crystal display device, the selectivity of the refractive index anisotropy (Δn) of the liquid crystal is unnecessary and the thickness of the liquid crystal layer is reduced. It is possible to obtain a high-quality liquid crystal display device which is enlarged and has increased margin in what is called a manufacturing process, and has no display unevenness.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an operation of liquid crystal in a liquid crystal display device of the present invention.

FIG. 2 is an explanatory diagram showing an angle formed by a molecular long axis orientation direction (rubbing direction) φ _LC on the interface and a polarizing plate polarization axis direction φ _P with respect to an electric field direction.

FIG. 3 is an explanatory diagram showing a structure of a thin film transistor, an electrode and a wiring of the present invention.

FIG. 4 is an electro-optical characteristic diagram of the present invention.

FIG. 5 is an explanatory diagram showing an arrangement of a plurality of pixels of the display device of the present invention.

FIG. 6 is an explanatory diagram showing an arrangement of a plurality of pixels of the display device of the present invention.

FIG. 7 is a process drawing showing the manufacturing process of the display device of the present invention.

FIG. 8 is a process drawing showing the manufacturing process of the display device of the present invention.

FIG. 9 is a process drawing showing the manufacturing process of the display device of the present invention.

FIG. 10 is a side sectional view of a liquid crystal display device of the present invention equipped with a color filter.

FIG. 11 is a timing chart showing a method for producing a color filter of the present invention.

FIG. 12 is an explanatory view of another embodiment of the color filter of the invention.

FIG. 13 is a circuit diagram of the present invention.

FIG. 14 is another drive waveform diagram of the present invention.

FIG. 15 is an explanatory diagram showing the measurement results of the present invention.

[Explanation of symbols]

1 ... Common electrode, 2 ... Gate insulating film, 3 ... Signal electrode, 4 ...
Pixel electrode, 7 ... Substrate, 12 ... Scan electrode, 13 ... Amorphous silicon.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Shiro 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd. Electronic Device Division (72) Inventor Katsumi Kondo 7-1, 1-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor Shin Yoneya 7-1-1 Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Hitachi Research Laboratory

Claims (5)

[Claims] 1. A liquid crystal element comprising an electrode, a driving means, an alignment film and a polarizing plate, wherein a pixel electrode is formed on one substrate and no electrode is formed on the other substrate. In a lateral electric field drive type liquid crystal display device having a structure in which the pixel electrode applies an electric field mainly to the liquid crystal layer in parallel to the substrate surface, the liquid crystal molecule sandwiched between the pixel electrode substrate and the non-pixel electrode substrate and the liquid crystal molecule The angle with the interface of the substrate is 5 degrees or more 30
And a liquid crystal layer having a thickness of more than 4 μm and 10 μm or less. 2. The method according to claim 1, wherein the alignment films formed on the pixel electrode substrate and the non-pixel electrode substrate are rubbed and combined so that the rubbing directions thereof are substantially parallel to each other, and a polarizing plate is provided outside each substrate. A liquid crystal display device in which a polarizing plate is provided and the polarization axes of the polarizing plates are orthogonal to each other to provide a birefringent display mode. 3. The liquid crystal display device according to claim 1, wherein an active element is formed on the pixel electrode substrate. 4. A liquid crystal display device according to claim 1, wherein RGB color filters are formed on a non-pixel electrode substrate. 5. The liquid crystal display device according to claim 1, wherein the pixel electrode substrate is formed in a comb shape.