JP3237484B2 - Active matrix type liquid crystal display device and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display and a method of manufacturing the same.

[0002]

2. Description of the Related Art An active matrix type liquid crystal display device using an active element represented by a thin film transistor (TFT) is widely used as a display terminal of OA equipment and the like because of its thinness and light weight and high image quality comparable to a cathode ray tube. Have begun to do. As a display method of this liquid crystal display device, a liquid crystal is operated by an electric field substantially parallel to a substrate surface between two electrodes formed on the same substrate, and light incident on the liquid crystal from a gap between the two electrodes is modulated for display. In recent years, a so-called horizontal electric field method has been known. This method has a feature of a wide viewing angle, and is a promising technology as an active matrix liquid crystal display device for an image display device typified by a TV, which is assumed to be viewed by a large number of people. Regarding the features of this method, see Patent Application Publication No. 5-5.
05247, and JP-B-63-21907.

[0003]

However, in the liquid crystal display device using the liquid crystal display system, a potential irrelevant to the display potential is always applied between the signal wiring and the adjacent electrode.
It was necessary to shield the region between these regions with a light shielding layer.
If the boundary of the light-shielding layer is provided in the display area, the light can be surely shielded, but in this case, the aperture ratio decreases. In addition, if the boundary of the light-shielding layer is provided on an electrode adjacent to the signal wiring, a decrease in the aperture ratio can be prevented. .

[0004]

According to the present invention, there is provided an active matrix liquid crystal display device having the following features.

(Means 1) In two transparent substrates opposed to each other via a liquid crystal layer, a display electrode, a reference electrode, a scanning signal line, a video signal line, and a display electrode are provided in each pixel region on one of the transparent substrates. An active element is provided, and the voltage applied between the display electrode and the reference electrode causes the aforementioned 2
In a liquid crystal display device that modulates light transmitted through the liquid crystal layer by generating an electric field that is substantially parallel to the one transparent substrate, the video signal line and the video signal line are interposed via an insulating layer. It has a reference electrode arranged adjacently in parallel, and the video signal line and the reference electrode have an overlapping portion in a plane via the insulating layer, and in the pixel region, on the other transparent substrate side The formed light shielding layer is arranged only in a direction substantially parallel to the scanning signal line.

(Means 2) In two transparent substrates disposed to face each other via a liquid crystal layer, a display electrode, a reference electrode, a scanning signal line, a video signal line, and a An active element is provided, and the voltage applied between the display electrode and the reference electrode causes the aforementioned 2
In a liquid crystal display device that modulates light transmitted through the liquid crystal layer by generating an electric field that is substantially parallel to the one transparent substrate, the video signal line and the video signal line are interposed via an insulating layer. It has two reference electrodes that are arranged in parallel and adjacent to each other and that are spaced apart from each other and branched from a reference signal line,
The video signal line and the two reference electrodes have a superimposed portion in a plane with the insulating layer interposed therebetween, and the light-shielding layer formed on the other transparent substrate side is substantially parallel to the scanning signal line. Only in the correct direction.

(Means 3) The light shielding layer is made linear in the pixel area.

(Means 4) The light-shielding layer is manufactured by a printing method.

(Means 5) A light-shielding layer and a colored layer of three primary colors are manufactured by a printing method.

[0010]

Next, the operation of the present invention will be described.

(Function 1) In a liquid crystal display device using a so-called in-plane switching method, between a video signal line and an adjacent electrode,
Since a potential irrelevant to the potential between the display electrode and the reference electrode is always applied, it is necessary to shield the region between the display electrode and the reference electrode with a light shielding layer. When the space between the video signal line and the adjacent electrode is shielded by an independent light shielding layer arranged so as to be superimposed on the video signal line in the display area, the boundary line of the light shielding layer is taken into consideration in consideration of the alignment margin of the upper and lower substrates. Must be protruded from the reference electrode into the pixel and provided in the display area, and the aperture ratio is reduced accordingly. Therefore, in the present invention, a reference electrode is provided adjacent to a video signal line, and by providing a superimposed portion on the video signal line and the reference electrode, the reference electrode has the effect of a light-shielding layer, Light is shielded between the reference electrodes.
In this case, there is no need for an independent light-shielding layer arranged so as to overlap the video signal line in the display area. Thereby, the boundary of the portion having the light blocking effect is determined as the boundary of the reference electrode, and the aperture ratio is improved. At this time, it goes without saying that the video signal line and the reference electrode need to be formed of an opaque conductive material. Further, the light-shielding layer may be superimposed on the scanning signal line in a plane, and may be arranged only in a direction along the scanning signal line. As a result, with respect to the alignment margin of the upper and lower substrates, in the direction parallel to the scanning signal lines, the boundary between the three primary color coloring layers of the color filter is any one between the reference electrode and the reference electrode sandwiching the video signal line. Since it only needs to be in the area, it can be greatly expanded. Further, with respect to the direction perpendicular to the scanning signal lines,
Since the alignment is performed on the long side, the influence of the positional shift on the aperture ratio is significantly smaller than that on the short side, so that the alignment margin of the upper and lower substrates can be greatly increased.

Further, a so-called vertical electric field type liquid crystal display element, in which a metal layer having a superimposed portion on a video signal line is provided on the same substrate as a video signal line, can be constructed similarly to the present invention. However, in this case, it is necessary to provide a planar overlapping portion between the display electrode which is a transparent electrode and the metal layer, so that the value of the load capacitance connected to the display electrode increases. For this reason, in particular, there is a problem that the video information stored in the display electrode is likely to fluctuate, the intensity of the luminance fluctuation increases, and the image quality deteriorates. These problems are problems that do not occur when realizing the configuration of the present invention in a so-called in-plane switching mode liquid crystal display element, that is, the configuration of the present invention is most effective in a so-called in-plane switching mode liquid crystal display element. Can be said.

(Function 2) When the reference electrode is formed so as to cover the entire surface under the signal wiring, the capacitance between the reference electrode and the signal wiring increases. This means that the capacitance component connected to the reference signal line increases, and the horizontal smear increases. Therefore, two reference electrodes branched from the reference signal line are arranged at a distance from each other below the video signal line. Thus, the overlapping area of the video signal line and the reference electrode can be reduced, so that the capacitance component can be reduced. Thus, this can reduce the level of lateral smear.

(Function 3) By forming the light-shielding layer linearly in the display area, the structure of the light-shielding layer can be simplified. This means that the light-shielding layer can be formed without using a photo process, and the degree of freedom in selecting a manufacturing process can be increased.

(Function 4) If the light-shielding layer is only in the direction parallel to the scanning signal lines in the display area, the light-shielding layer pattern is simplified, so that the printing method can be easily applied to the formation of the light-shielding layer. In particular, in the case of a straight line, the pattern becomes extremely simple, so that the light-shielding layer can be formed by a simple printing manufacturing process. Thereby, it is possible to improve the productivity and reduce the production cost.

(Function 5) Further, by forming the coloring layers of the three primary colors by the printing method, the need for an exposure apparatus is eliminated. This can reduce capital investment.

[0017]

【Example】

Embodiment 1 In this embodiment, a panel having the following configuration was used as a liquid crystal display panel.

As the substrates, two transparent glass substrates 101 and 201 having a thickness of 1.1 mm and a polished surface were used.

A thin film transistor was formed on one of the substrates 101. FIG. 1A shows a transparent substrate 1.
FIG. 3 shows a plan view of a pixel on the 01 side. 102 is a scanning signal line, 103 is a video signal line, 104 is a display electrode, 105 is a reference electrode, and 109 is a reference signal line. FIG. 1B is a plan view showing a relative positional relationship between the light shielding layer 202 on the transparent substrate 201 side and the pixels on the transparent substrate 101 side. In the present embodiment, it is provided only in the direction along the scanning signal line. The light shielding in the direction perpendicular to the scanning signal line was performed by overlapping the video signal line and the adjacent reference electrode via an insulating film. A reference electrode adjacent to the video signal line was integrally formed between pixels adjacent in the row direction. FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. The orientation of the liquid crystal molecules 301 of the liquid crystal layer 300 is controlled by the electric field E between the display electrode 104 and the reference electrode 105 formed on the substrate 101, and the brightness of light incident from between the display electrode 104 and the reference electrode 105 is increased. Is modulated and emitted. On the other substrate 201, a light-shielding layer, a colored layer of three primary colors, and the like were formed. A transparent resin 204 for planarizing the surface is provided on the three primary color layers 203.
Were laminated.

An alignment film 12 is formed on the outermost surfaces of these two substrates.
After the rubbing process is performed, the liquid crystal composition 300 is sealed between the substrates, and the liquid crystal composition 300 is sealed with two polarizing plates 13.
The liquid crystal display panel was formed by sandwiching the liquid crystal display panel with the reference numerals 0 and 230.

FIG. 8 shows the relationship among the electric field direction, the rubbing direction, and the polarization transmission axis. In this embodiment, polyimide is used as the alignment film. The rubbing directions on the upper and lower interfaces were substantially parallel to each other, and the angle φLC formed with the direction of the applied electric field was 85 degrees. As the liquid crystal composition 300, a nematic liquid crystal composition having a positive dielectric anisotropy Δε, a value of 7.3 (1 KHz), and a refractive index anisotropy Δn of 0.073 (589 nm, 20 ° C.) is used. Using. The gap d between the substrates was 4.1 μm in a state where liquid crystal was sealed, with spherical polymer beads dispersed and sandwiched between the substrates. G12 manufactured by Nitto Denko Corporation as a polarizing plate
Using 20DU, the polarization transmission axis of one of the polarizing plates was set at almost the same angle as the rubbing direction, that is, φP = 85 °, and the other was set perpendicular to it. FIG. 3 is a cross-sectional view taken along line BB ′ of FIG. 1A, and shows a cross-sectional structure of the thin film transistor element. The thin film transistor element was composed of a display electrode 104 (source electrode), a video signal line 103 (drain electrode), a scanning signal line 102 (gate electrode), and amorphous silicon 106. The thin film transistor element 150 has an inverted staggered structure, the scanning signal line 102 is formed in the lowermost layer, the gate insulating film 108, the amorphous silicon 106
Are sequentially formed, and the video signal line 103 and the display electrode 104 are formed on the same metal layer. In order to make ohmic contact between the amorphous silicon 106 and the video signal line 103 and the display electrode 104, an n + type amorphous silicon 107 doped with phosphorus was formed therebetween. FIG. 4 is a cross-sectional view taken along line CC ′ in FIG. 1A, and shows a cross-sectional structure of the storage capacitor Cstg. The gate insulating film 108 was sandwiched between the display electrode 104 and the reference signal line 109. As the reference electrode 105, the reference signal line 10
A protrusion extending from 9 was used.

FIG. 7 shows a peripheral circuit of this embodiment. The liquid crystal display element 400 includes a vertical scanning circuit 403 and a video signal driving circuit 404 as external circuits, and the vertical scanning circuit 403 sequentially supplies a scanning signal (voltage) to each of the scanning signal lines 102. The video signal drive circuit 404 supplies a video signal (voltage) to the video signal line 103 in accordance with the timing.

The vertical scanning circuit 403 and the video signal driving circuit 404 are supplied with a voltage from the liquid crystal driving power supply circuit 402, and the image information from the CPU is divided into display data and control signals by the controller 401. To be entered.

The voltage applied to the reference signal line 109 is also supplied from the liquid crystal drive power supply circuit 402. In this embodiment, an AC voltage is used as the voltage applied to the reference signal line 109 for the purpose of reducing the withstand voltage of the video signal driving circuit 404.

In this embodiment, since the reference electrode formed so as to be superimposed on the video signal line also serves as a light shielding layer, a liquid crystal display device having a high aperture ratio can be realized. In the present embodiment, by providing the light shielding layer only in the direction along the scanning signal line, the alignment margin of the upper and lower substrates can be greatly increased.

In a so-called vertical electric field type liquid crystal display element, a structure similar to the present invention can be achieved by providing a metal layer having a superimposed portion on a video signal line on the same substrate as the video signal line. However, in this case, it is necessary to provide a superimposed portion also on the display electrode which is a transparent electrode and the metal layer, so that the value of the load capacitance connected to the display electrode increases. For this reason, in particular, there is a problem that the video information stored in the display electrode is likely to fluctuate, the intensity of the luminance fluctuation increases, and the image quality deteriorates. These problems are problems that do not occur when realizing the configuration of the present invention in a so-called in-plane switching mode liquid crystal display element, that is, the configuration of the present invention is most effective in a so-called in-plane switching mode liquid crystal display element. Can be said.

Embodiment 2 This embodiment is different from Embodiment 1 only in the sectional structure of the pixel. FIG. 5 shows a cross-sectional structure of the pixel of the present embodiment.

When the reference electrode is formed so as to cover the entire surface below the video signal line, the capacitance generated between the reference electrode and the video signal line increases. This means that the capacitance component connected to the reference signal line increases, resulting in an increase in horizontal smear. In this embodiment, the capacitance component can be reduced by arranging two reference electrodes branched from the reference signal line at a distance from each other below the video signal line,
As compared with the case of Example 1, the lateral smear was able to be reduced.

In this embodiment, the horizontal smear is reduced in addition to the effect of the first embodiment.

[Embodiment 3] The present embodiment is different from the embodiment 1 only in the planar shape of the light shielding layer. FIG. 6 shows a planar arrangement of the light-shielding layer of the pixel of this embodiment. In this embodiment, the light shielding layer is formed in a straight line. By forming the light shielding layer in a straight line in the display area, the structure of the light shielding layer can be simplified. This means that the light-shielding layer can be formed without using a photoresist step, and the degree of freedom in selecting a manufacturing process can be increased.

As described above, in this embodiment, in addition to the effects of the first embodiment, the degree of freedom in selecting a manufacturing process can be increased.

[Embodiment 4] In this embodiment, the light shielding layer of Embodiment 3 was formed by a printing method.

In this embodiment, after forming a metal film on the entire surface of the transparent substrate 201, a light shielding layer pattern is printed with a resist,
An unnecessary metal film was removed by etching, and then the resist was removed to form a light shielding layer. This eliminates the need for a photo step, improves productivity, and realizes low cost.

In this embodiment, a metal is used as a light-shielding layer material. However, any material having a light-shielding property is included in the category of this embodiment regardless of an organic material or an inorganic material.

[Embodiment 5] In this embodiment, the light-shielding layer is formed by printing in the same manner as in Embodiment 4. However, in this embodiment, a material mainly composed of an organic substance is used as the light-shielding layer material and the printing method is used. Directly formed a light-shielding layer. Thus, in the present embodiment, the pattern of the light-shielding layer can be formed only by the printing step of the steps of the fourth embodiment, so that the productivity is further improved and the cost is reduced as compared with the fourth embodiment.

[Embodiment 6] In this embodiment, after forming a light-shielding layer by the method of Embodiment 5, coloring layers of three primary colors were also formed by a printing method. This eliminates the need for an exposure apparatus in the process of manufacturing the light-shielding layer and the three primary color layers, thereby reducing capital investment.

[0037]

As described above, according to the liquid crystal display device of the present invention, the so-called aperture ratio can be improved. Also, the alignment margin of the upper and lower substrates is increased,
Productivity can be improved.

[Brief description of the drawings]

FIG. 1A is a plan structural view of a pixel on a transparent substrate 101 side. (b) shows the light shielding layer 202 on the transparent substrate 201 side.
FIG. 3 is a plan view showing a relative positional relationship between the pixel and a pixel on the transparent substrate 101 side.

FIG. 2 is a diagram illustrating a cross-sectional structure of a pixel portion taken along line AA ′ of FIG.

FIG. 3 is a diagram illustrating a cross-sectional structure of a pixel portion taken along line BB ′ of FIG.

FIG. 4 is a diagram illustrating a cross-sectional structure of a pixel portion taken along line CC ′ of FIG.

FIG. 5 is a diagram illustrating a cross-sectional structure of a pixel unit according to a second embodiment.

FIG. 6 is a view showing a light shielding layer of a third embodiment.

FIG. 7 is a diagram illustrating a peripheral circuit of the liquid crystal display device.

FIG. 8 is a diagram illustrating an angle formed by a molecular long axis alignment direction (rubbing direction) φLC on an interface with respect to an electric field direction and an angle formed by a deflection plate transmission axis φP of one of the deflection plates with respect to the electric field direction.

[Explanation of symbols]

100 lower substrate, 101 glass substrate, 102
Scanning signal line, 103 video signal line, 104 display electrode, 105 reference electrode, 106 amorphous silicon, 107 n + type amorphous silicon, 10
Reference Signs List 8 insulating film, 109 reference signal line, 110 protective film, 120 alignment film, 130 polarizing plate, 190 short-circuit part, 191 cut part, 201 glass substrate, 2
02 light shielding film, 203 color filter, 204
Flattening film, 208 Molecular long axis alignment direction (rubbing direction) φLC, 209 Deflection plate transmission axis φP, 22
0 alignment film, 230 polarizing plate, 300 liquid crystal composition material, 301 liquid crystal molecules, 400 liquid crystal display panel,
401 controller, 402 liquid crystal power supply driving circuit,
403 vertical scanning circuit, 404 video signal driving circuit, 501 liquid crystal display panel

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Keiichiro Ashizawa 3300 Hayano Mobara-shi, Chiba Electronic Devices Division, Hitachi Ltd. (56) References JP-A-7-36058 (JP, A) JP-A-7-181439 (JP, A) JP-A-6-202073 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02F 1/1343 G02F 1/1362 G02F 1/1335

Claims (5)

(57) [Claims] 1. A display device, a reference electrode, a scanning signal line, a video signal line, and an active element in each of two pixel regions on one of two transparent substrates which are arranged to face each other via a liquid crystal layer. A liquid crystal display that modulates light transmitted through the liquid crystal layer by generating an electric field in the liquid crystal layer substantially parallel to the two transparent substrates by a voltage applied between a display electrode and a reference electrode. apparatus smell Te,
The reference electrode includes a plurality of reference electrodes, at least one of the plurality of reference electrodes.
The book extends along the video signal line, and the video signal
A superimposed portion that superimposes in a plane with the line via the insulating layer.
Formed Te, In or One pixel region is light-shielding layer formed on the other transparent substrate side is disposed only in a direction substantially parallel to the scanning signal lines, further side of the boundary of the colored layers of the three primary
On the video signal line or planar with the video signal line
Electrode having a superimposed portion superimposed on the insulating layer via the insulating layer
An active matrix liquid crystal display device having a structure positioned above . 2. A display device, a reference electrode, a scanning signal line, a video signal line, and an active element in each of two pixel regions on one of two transparent substrates opposed to each other via a liquid crystal layer. A liquid crystal display that modulates light transmitted through the liquid crystal layer by generating an electric field in the liquid crystal layer substantially parallel to the two transparent substrates by a voltage applied between a display electrode and a reference electrode. apparatus smell Te,
Extending along the front SL video signal lines, possess two reference electrodes branched from the reference signal line provided mutually spacing, the two
Opposing reference electrodes on each side of the reference electrode
Each of the side surfaces near the pole is planar with the video signal line.
And the two reference electrodes
The side of the side farthest from the opposing reference electrode
Each is formed at a position that does not overlap with the video signal line.
Is either One other active matrix type liquid crystal display device light-shielding layer formed on the transparent substrate side and having a placement structure only in the direction substantially parallel to the scanning signal lines. In 3. A direction parallel to the scanning signal line said light shielding layer in the pixel region, and an active matrix type liquid crystal display according to claim 1 and claim 2, characterized in that a linear apparatus. 4. A display electrode, a reference electrode, a scanning signal line, a video signal line, and an active element in each of two transparent substrates which are arranged to face each other with a liquid crystal layer therebetween. A liquid crystal display that modulates light transmitted through the liquid crystal layer by generating an electric field in the liquid crystal layer substantially parallel to the two transparent substrates by a voltage applied between a display electrode and a reference electrode. apparatus Te manufacturing method <br/> odor, the reference electrode is plural, small of which
At least one extends along the video signal line, and
The weight overlapping with the video signal line in a plane via the insulating layer
Formed with a tatami section, in either One pixel region is light-shielding layer formed on the other transparent substrate side is disposed only in a direction substantially parallel to the scanning signal lines, further boundary of the colored layers of three primary colors
One side of the field is on the video signal line or the video signal
It has an overlapping portion that overlaps with the line through the insulating layer in a plane.
A method for manufacturing an active matrix type liquid crystal display device having a structure positioned on a reference electrode , and manufacturing the light shielding layer by a printing method. 5. The method for manufacturing an active matrix type liquid crystal display device according to claim 4, wherein said light shielding layer and said three primary color layers are manufactured by a printing method.