JPH11295712A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent light from leaking from an outer periphery of an effective display area of a liquid crystal display device. SOLUTION: This liquid crystal display device is constituted by being provided with at least an electrode group and a wiring electrode group for the picture element selection on an inner surfaces of at least one of a couple of substrates SUB2, SUB1, and plural color filters divided by inner surface shading layers BM on an inner surface of the other substrate, a liquid crystal panel PNL holding a liquid crystal layer LC in the space between the pair of opposing substrates, and a driving circuit for impressing a voltage for picture element selection to the electrode group through the wiring electrode group. In this case, the inner surface shading layers BM of the other substrate are formed also in the periphery of an effective display area on the substrate, and also an outside surface shading layer FMS is also provided which is formed in the area spanning to the position corresponding to the outer peripheral side end face of the inner surface shading layers BM from the end face of the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having improved display quality by preventing light leakage from a periphery of an effective display area.

[0002]

2. Description of the Related Art A liquid crystal display device has been widely used as a display device capable of high-definition and color display for a notebook computer or a display monitor.

In a liquid crystal display device, a pair of substrates having a large number of electrodes arranged in parallel are bonded so that the electron guns cross each other, and a liquid crystal display device of a simple matrix type (generally, a liquid crystal is sandwiched in a bonding gap). , STN type liquid crystal display devices) and active matrix type liquid crystal display devices provided with switching elements for pixel selection for each unit pixel.

[0004] In particular, as a so-called active matrix type liquid crystal display device, a so-called twisted nematic (TN) system is used, which is a so-called liquid crystal panel using a pixel selection electrode group formed on each of a pair of upper and lower substrates. A so-called horizontal electric field type liquid crystal display using a vertical electric field type liquid crystal display device (generally called a TN type liquid crystal display device) and a liquid crystal panel in which an electrode group for pixel selection is formed on only one of a pair of upper and lower substrates. Device (generally referred to as an IPS mode liquid crystal display device).

In a liquid crystal panel constituting the former TN mode liquid crystal display device, the liquid crystal is twisted by 90 ° in a pair of (two) substrates, and the absorption axis directions are arranged on the outer surfaces of the upper and lower substrates of the liquid crystal panel. Two polarizing plates are arranged in a crossed Nicols state and the absorption axes on the incident side are parallel or perpendicular to the rubbing direction. When the rubbing direction is parallel to the absorption axis of the polarizing plate, it is called an "O" mode, and when it is perpendicular, it is called an "E" mode.

In such a TN type liquid crystal display device, when no voltage is applied, incident light becomes linearly polarized light by an incident side polarizing plate.
The linearly polarized light propagates along the twist of the liquid crystal layer, and when the transmission axis of the exit-side polarizing plate matches the azimuth of the linearly polarized light, all of the linearly polarized light is emitted to form a white display (a so-called “no”). Mari open arrangement).

When a voltage is applied, the direction (director) of a unit vector indicating the average alignment direction of the liquid crystal molecular axes constituting the liquid crystal layer is oriented in a direction perpendicular to the substrate surface, and the azimuth of the incident side linearly polarized light. Since the angle does not change, it coincides with the absorption axis of the exit-side polarizing plate, so that black display is performed. (See "Basics and Applications of Liquid Crystals" published by the Industrial Research Council in 1991).

On the other hand, an electrode group for pixel selection and an electrode wiring group are formed only on one of a pair of substrates, and a voltage is applied between adjacent electrodes (between a pixel electrode and a counter electrode) on the substrate by applying a voltage. In an IPS type liquid crystal display device in which layers are switched in a direction parallel to the substrate surface, a polarizing plate is arranged so as to display black when no voltage is applied (a so-called normally closed arrangement).

The liquid crystal layer of this IPS mode liquid crystal display device is
In the initial state, the director of the liquid crystal layer is in a homogeneous orientation parallel to the substrate surface, and in a plane parallel to the substrate, the director of the liquid crystal layer is parallel or somewhat angled with the electrode wiring direction when no voltage is applied, and the liquid crystal layer is oriented when the voltage is applied. The direction of the director shifts in a direction perpendicular to the electrode wiring direction with the application of the voltage, and the director direction of the liquid crystal layer is 45 times smaller than the director direction when no voltage is applied.
° When tilted in the electrode wiring direction, the liquid crystal layer at the time of applying the voltage has an azimuth of 90 degrees of polarization as if it were a half-wave plate.
And the azimuth of the polarized light coincides with the transmission axis of the exit-side polarizing plate, and a white display is obtained.

The IPS mode liquid crystal display device has a feature that a change in hue and contrast is small even at a viewing angle, and a wide viewing angle is achieved (Japanese Patent Laid-Open No. 5-50).
No. 5247).

In the IPS mode liquid crystal display device, since it is necessary to form an electric field parallel to the substrate, a structure in which a pixel electrode and a reference electrode are formed in a comb shape on one substrate is employed. A signal voltage is supplied from a video signal line to a pixel electrode through a switching element (generally, a thin film transistor: TFT; the switching element is hereinafter described as a thin film transistor TFT), and a reference voltage is supplied from a reference signal line to a reference electrode. You.

A TFT is formed by using a plurality of steps of a photolithography technique.
In order to reduce the number of photolithography steps, a direction perpendicular to the extending direction of the video signal line, a direction parallel to the scanning signal line, and a direction perpendicular to the pixel electrode and the reference electrode are formed.

In a liquid crystal panel used in such a liquid crystal display device, it is necessary for display quality to prevent light leakage from the periphery outside the effective display area. For this reason, a method of forming a light-shielding layer in a peripheral portion is generally used. Further, the light shielding layer is superimposed on the frame above the liquid crystal panel to shield the light.

[0014]

Generally, an adhesive spacer (hereinafter referred to as an adhesive tape) for fixing the liquid crystal panel is interposed between the liquid crystal panel and the frame. For this reason, the distance between the liquid crystal panel and the frame is
There is a problem that it is difficult to shade the surrounding area.

FIG. 14 is a sectional view of an essential part for explaining an example of an assembling structure of a liquid crystal panel and a frame of a conventional liquid crystal display device. Liquid crystal layer L between lower substrate SUB1 and upper substrate SUB2
C and a backlight BL installed on the back of the liquid crystal panel PNL together with a drive circuit board (not shown) and other components.
The liquid crystal display device is constituted by fixing at D.

The periphery of a pair of substrates (lower substrate SUB1 and upper substrate SUB2) constituting the liquid crystal panel PNL is sealed with a sealing material SL. Also, in the figure, the upper substrate SUB
A plurality of color filters FIL partitioned by a black matrix BM, which is a light-shielding layer, are formed on the inner surface of the second filter 2.
On the inner surfaces of the pair of substrates, other electrodes, wiring electrodes, or polarizing plates, and other functional member groups that are different depending on the display format of the liquid crystal display device are formed or laminated, but are not shown here. .

In FIG. 14, the light leaked from the backlight BL in the oblique direction is, as shown in FIG.
Of the black matrix BM and the frame SH
It starts to leak from the direction of the straight line connecting the inner ends of the windows of D. Upper substrate SU on which frame SHD and color filter FIL are formed
Let L _{1 be} the light leaked from the backlight BL when the adhesive tape BAT is interposed between B1 and B2, and let α be the angle formed by the surface of the upper substrate SUB2. If this adhesive tape BAT
If not, it becomes into contact with the upper and lower and upper substrate SUB2 of the liquid crystal panel and the frame SHD 'shown in phantom, the leakage light L ₂ in an oblique direction from the backlight BL is the surface of the upper substrate SUB2 Becomes the light of β, β
<< leakage light L ₂ at α since becomes visible difficult from viewing angle direction (the plane substantially perpendicular direction of the liquid crystal panel), a special light shielding means is not necessary.

However, as shown, the adhesive tape BA
Provided T is obtained by the measures of the displacement resolution of the liquid crystal panel PNL and the frame SHD, L ₁ and leakage light from the backlight BL in the effective display region around the liquid crystal panel PNL is emitted at an angle α close to the viewing angle direction Therefore, there has been a problem that it is difficult to shield the surrounding area.

As a solution, the inner edge of the window of the frame SHD should be closer to the effective display area. However, according to this method, the alignment tolerance between the frame and the liquid crystal panel PNL becomes a problem, and it is not possible to cope with the so-called narrowing of the frame, that is, to reduce the dimension from the effective area to the end face of the substrate of the liquid crystal panel PNL.

As another solution, a black matrix B
A technique of forming M up to the end face of the substrate of the liquid crystal panel PNL is known. However, in this method, when the black matrix BM is made of a metal material, the metal edge is exposed to the air, and thus there is a problem that the reliability is reduced due to electric contact. In addition, when the black matrix is formed of an organic resin material, there is a problem that peeling occurs at the end face of the substrate due to stress at the time of cutting the substrate when manufacturing the liquid crystal panel, and light cannot be blocked.

An object of the present invention is to solve the above-mentioned problems of the prior art, to prevent the black matrix from being exposed on the end face of the substrate of the liquid crystal panel, and to provide a light shielding performance around an effective display area equivalent to that without an adhesive tape. It is an object of the present invention to provide a liquid crystal display device capable of displaying a high quality image by improving image quality.

[0022]

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention is characterized by having the following constitutions (1) to (8).

(1) An electrode group for selecting pixels and a wiring electrode group are provided on the inner surface of at least one of the pair of substrates,
A liquid crystal panel having a plurality of color filters separated by an inner light-shielding layer on the inner surface of the other substrate, and a liquid crystal panel sandwiching a liquid crystal layer in an opposing gap between the pair of substrates, and the electrode group via the wiring electrode group; A drive circuit for applying a voltage for pixel selection, and the inner surface light-shielding layer of the other substrate is also formed around an effective display area of the substrate, and on the outer surface of the other substrate. An outer light-shielding layer was formed at least in a region from an end surface of the substrate to a position corresponding to an outer-side end surface of the inner light-shielding layer.

With this configuration, it is possible to prevent the visibility of the screen display from being degraded due to the leakage light from the backlight at the outer periphery of the effective display area, and to obtain a high quality display image.

(2) Pixel selection electrodes, wiring electrodes, and switching elements are provided only on the inner surface of one of the pair of substrates, and a plurality of colors are defined on the inner surface of the other substrate by an inner light-shielding layer. A liquid crystal panel having a color filter, and a liquid crystal layer sandwiched between opposing gaps of the pair of substrates; and a drive circuit for selectively applying a pixel selection voltage to the switching element group via the wiring electrode group. At least the inner light-shielding layer of the other substrate is also formed around an effective display area of the other substrate, and at least the inner light-shielding layer is formed on an outer surface of the other substrate from an end surface of the substrate. The outer light-shielding layer was formed in a region reaching a position corresponding to the outer peripheral side end surface of the above.

With this configuration, it is possible to prevent the visibility of the screen display from being degraded due to the leakage light from the backlight in the outer periphery of the effective display area, and to obtain a high quality display image.

(3) A frame provided with a window having an inner end on the outer periphery of the effective display area of the liquid crystal panel in (1) or (2), wherein the inner light-shielding layer of the upper substrate is provided on the other substrate. Around the effective display area of
On the outer surface of the other substrate, an outer light-shielding layer was formed in a region from the inner end of the window of the frame to a position corresponding to the outer-side end surface of the inner light-shielding layer.

With this configuration, it is possible to prevent the leakage of light from the frame and to prevent the visibility of the screen display from being degraded due to the leakage of light from the backlight in the outer periphery of the effective display area of the liquid crystal panel, so that a high quality display image can be obtained.

(4) The surface light-shielding layer in (1), (2) or (3) was formed of a metal material, and the inner surface light-shielding layer was formed of an organic material.

Since the organic material and the metal material use different chemicals in the photolithography process, the patterning of the black matrix or color filter formed on the inner surface of the other substrate and the patterning process of the surface light-shielding layer formed on the outer surface are performed. Thus, a desired pattern can be stably created without any mutual influences. In particular, the effect is great for the other substrate of the horizontal electric field type having no metal film on the inner surface.

(5) A transparent conductive film is formed on the entire surface of the upper substrate so as to cover the surface light-shielding layer in any one of (1) to (4).

(6) The surface light-shielding layer in any one of (1) to (4) was formed on the transparent conductive layer.

(7) The surface light-shielding layer in (5) or (6) is formed of a metal material. (8) The transparent conductive layer in (5) or (6) was electrically connected to the frame.

According to the above constitutions (6) to (8), light leakage from the backlight can be prevented, and at the same time, electrostatic charge on the screen of the liquid crystal panel can be prevented, so that a high-quality image display can be obtained.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to examples.

Embodiment 1 (corresponding to claim 1) FIG. 1 is a cross-sectional view of a principal part schematically showing a configuration of a first embodiment of a liquid crystal display device according to the present invention, and FIG. 2 is a sectional view of the liquid crystal display device of FIG. It is sectional drawing which shows the whole structure typically.

In FIGS. 1 and 2, SHD is a frame (generally made of metal), BAT is an adhesive tape, FSM is an outer light-shielding film, SUB2 is an upper substrate, BM is an inner light-shielding film (black matrix), and LC is a liquid crystal layer. , SUB1 is a lower substrate,
SL seal material and BL indicate a backlight. And P
NL is a liquid crystal panel.

The liquid crystal panel PNL has a pair of substrates SUB1 and SUB2 composed of a lower substrate SUB1 which is one substrate and an upper substrate SUB2 which is the other substrate, and a seal sandwiched between opposing gaps of the pair of substrates SUB1 and SUB2. Material S
It has a liquid crystal layer LC sealed with L. Lower substrate SUB
1 and an inner surface of the upper substrate SUB2, an electrode group, a wiring electrode group, a switching element, and other functional members corresponding to the operation mode of the liquid crystal display device are formed on each substrate.
Here, illustration is omitted.

A backlight BL for illumination is arranged on the back of the liquid crystal panel PNL.
L is integrally fixed with a drive circuit board and the like (not shown) by a frame SHD around an upper substrate SUB2 through an adhesive tape BAT. The light from the backlight BL illuminates the liquid crystal panel PNL to visualize the image formed on the liquid crystal panel PNL. Although an appropriate spacer is interposed between the liquid crystal panel PNL and the backlight BL, it is not shown.

The surface light-shielding layer FSM shown in FIG. 1 is formed in a region from the substrate end surface of the upper substrate SUB2 constituting the liquid crystal panel PNL to at least the end surface of the black matrix BM, and controls the behavior of the liquid crystal in pixel units. It is not formed at a position corresponding to a possible display area (effective display area).

FIG. 3 is a cross-sectional view of a principal part of a liquid crystal display device schematically illustrating the effect of the present embodiment. In the structure of the above-described embodiment, a black matrix BL as an inner light shielding layer and a surface light shielding layer FSM are used. shading is performed, the light L ₁ from the backlight BL shown in FIG. 20 does not reach the effective display area, the light L from the backlight BL begins to leak in the effective region
₂ becomes small, and the position of the end face of the front light shielding layer FSM on the effective display area side and the end face of the frame SHD are the upper substrate S
UB2 direction perpendicular position but becomes maximum when the same, the light L ₂ is deviated from the viewing angle direction, the invisibility from normal viewing angle.

As is apparent from the configuration shown in FIG. 3, if the outer peripheral edge of the black matrix BM is extended toward the outer peripheral side of the liquid crystal panel PNL to increase the amount of overlap with the outer light-shielding layer FSM, the light L ₂ is increased. Can be prevented from being emitted to the effective display area.

According to this embodiment, light leakage around the effective display area of the liquid crystal display device can be suppressed and a high quality image display can be obtained.

[Embodiment 2] FIG. 4 is a cross-sectional view schematically showing a main part of a liquid crystal display device according to a second embodiment of the present invention. The surface light-shielding layer FMS in FIG. 1 does not necessarily need to be formed from the inner end of the window of the frame SHD to the edge of the substrate of the liquid crystal panel. Therefore, in the present embodiment, the surface light-shielding layer FMS is provided at least from the inner edge of the window of the frame SHD to the outer edge of the black matrix formed on the outer edge of the effective display area on the inner surface of the upper substrate SUB2 of the liquid crystal panel ( (The range indicated by D in FIG. 4).

According to the present embodiment, similarly to the first embodiment, light leakage from the backlight can be prevented, and a high-quality image display can be obtained.

[Embodiment 3] In this embodiment, the surface light shielding layer FSM in the first embodiment or the second embodiment is formed of a metal material, and the black matrix BM is formed of an organic material.

In particular, in the liquid crystal display device of the horizontal electric field type, the upper substrate SUB2 constituting the liquid crystal panel does not originally have a functional layer using a metal material. That is, the upper substrate SUB2 of the horizontal electric field method is generally called a color filter substrate (C / F substrate), and has a color filter of an organic material and a black matrix on its inner surface.

Usually, an etching solution for patterning using a photolithography technique is different between a metal material and an organic material. An etching solution for a metal material does not etch an organic material, and vice versa. Nor.

Therefore, according to the present embodiment, the black matrix BM is formed of an organic material, and the surface light shielding layer FMS
Is formed of a metal material, there is no adverse effect that mutual etching is performed in the patterning step, and accurate patterning is performed in each target shape.

[Embodiment 4] FIG. 5 is a cross-sectional view schematically showing a main part of a liquid crystal display according to a fourth embodiment of the present invention.

This embodiment is different from the first embodiment described with reference to FIG. 1 in that a transparent conductive film is formed so as to cover the entire upper surface of the surface light shielding layer FMS formed on the upper substrate SUB2 of the liquid crystal panel PNL. In that the layer TCL is formed.

According to this embodiment, it is possible to prevent static electricity from being charged on the surface of the liquid crystal panel PNL, prevent light leakage from the backlight, and obtain a high-quality image display.

Since the frame SHD is generally made of a metal material, by making the adhesive tape BAT conductive and electrically connecting it to the layer TCL of the transparent conductive film, the static electricity charged on the layer TCL of the transparent conductive film reduces the frame SHD. Thus, it is possible to completely prevent the adverse effects caused by static electricity being charged on the display surface of the liquid crystal panel PNL.

[Embodiment 5] FIG. 6 is a cross-sectional view schematically showing a main part of a fifth embodiment of the liquid crystal display device according to the present invention.

In this embodiment, the transparent conductive film layer TCL in the fourth embodiment described with reference to FIG. 5 is formed below the surface light-shielding layer FSM. That is, after forming the layer TCL of the transparent conductive film over the entire surface of the upper substrate SUB2 of the liquid crystal panel PNL, the surface light shielding layer FSM was formed on the outer periphery of the liquid crystal panel PNL in the same manner as in the fourth embodiment.

According to the present embodiment, when the frame SHD and the outer edge of the liquid crystal panel PNL are extremely close to each other (so-called narrower frame), the light propagates through the transparent conductive layer TCL and leaks to the effective display area. Light can also be completely blocked, and a higher quality image display than in the fourth embodiment can be obtained.

Also in this embodiment, the frame SH
Since D is generally made of a metal material, by making the adhesive tape BAT conductive and making an electrical connection with the transparent conductive film layer TCL, static electricity charged on the transparent conductive film layer TCL is grounded via the frame SHD. Flow, liquid crystal panel PN
The problem caused by the electrification of the display surface of L with static electricity can be completely prevented.

[Embodiment 6] This embodiment is the same as the fourth embodiment except that the surface light-shielding layer FMS in the fourth embodiment is formed of a metal material.

[Embodiment 7] This embodiment has the same configuration as that of the fifth embodiment except that the surface light-shielding layer FMS in the fifth embodiment is formed of a metal material.

According to the sixth and seventh embodiments, the frame SHD is formed so as to cover the outer periphery of the transparent conductive layer TCL.
Surface light-shielding layer FM laminated with adhesive tape BAT
Since S has a low resistance, it is possible to completely prevent adverse effects caused by static electricity being charged on the display surface of the liquid crystal panel PNL.

Further, by forming the above-mentioned surface light-shielding layer FSM with a metal material, it becomes a measure against electromagnetic wave leakage, so-called E
MI can be reduced.

In each of the embodiments described above, the structure of the polarizing plate, the alignment film, the switching element (TFT, etc.) and other structures are omitted, but the actual liquid crystal display element includes these. Needless to say.

The surface light-shielding layer FMS can be formed by a sputtering method, a CVD method, a coating method or the like. Then, for the patterning, a resist coating + photolithography technique can be used. Further, a target shape can be directly obtained by a mask sputtering method.

When an organic material is used for forming the surface light-shielding layer FMS, it can be formed directly on the surface of the liquid crystal panel by direct drawing or printing using a plate. When the surface light-shielding layer FMS is formed on the transparent conductive film, a mask is placed on a region where the surface light-shielding layer is not formed, and then electrolytic plating is performed while applying a voltage to the transparent conductive layer. By removing it, the surface light-shielding layer can be formed in a predetermined shape.

Next, as an example of a liquid crystal display device to which the present invention is applied, details of a horizontal electric field type liquid crystal display device will be described. It is needless to say that the present invention can be similarly applied to other types of liquid crystal display devices (vertical electric field type, simple matrix type, etc.).

FIG. 7 is a plan view showing the periphery of one pixel of a horizontal electric field type color liquid crystal display device to which the present invention is applied. Each pixel has a scanning signal line (gate signal line or horizontal signal line) GL
, A counter voltage signal line (counter electrode line) CL, and two adjacent video signal lines (drain signal line or vertical signal line)
In the intersection area with DL (in the area surrounded by four signal lines)
Are located in

Each pixel includes a thin film transistor TFT, a storage capacitor Cstg, a pixel electrode PX, and a counter electrode CT. The scanning signal lines GL and the counter voltage signal lines CL extend in the left-right direction in FIG. The video signal lines DL extend in the up-down direction, and a plurality of video signal lines DL are arranged in the left-right direction. The pixel electrode PX is connected to the thin film transistor TFT, and the counter electrode CT is integrated with the counter voltage signal line CL.

The pixel electrode PX and the counter electrode CT are opposed to each other, and the alignment state of the liquid crystal LC is controlled by the electric field between each pixel electrode PX and the counter electrode CT, and the transmitted light is modulated to control the display. The pixel electrode PX and the counter electrode CT are formed in a comb-like shape, and each is an electrode that is elongated in the vertical direction in FIG.

The number O (number of comb teeth) of the counter electrode CT in one pixel is equal to the number P (number of comb teeth) of the pixel electrode PX and O =
It is configured to always have the relationship of P + 1 (O = 2, P = 1 in this embodiment). This is because the counter electrode CT and the pixel electrode PX are alternately arranged, and the counter electrode CT is always adjacent to the video signal line DL.

Thus, the counter electrode CT and the pixel electrode PX are
The electric field lines from the video signal line DL can be shielded by the counter electrode CT so that the electric field between them is not affected by the electric field generated from the video signal line DL.

Since the potential of the counter electrode CT is always supplied from the outside by the counter voltage signal line CL, the potential is stable. Therefore, there is almost no change in potential even adjacent to the video signal line DL. In addition, since the geometric position of the pixel electrode PX from the video signal line DL becomes farther,
The parasitic capacitance between the pixel electrode PX and the video signal line DL is greatly reduced, and the fluctuation of the pixel electrode potential Vs due to the video signal voltage can be controlled.

Thus, crosstalk (defective image quality called vertical smear) occurring in the vertical direction can be suppressed.

The electrode width W between the pixel electrode PX and the counter electrode CT
Each of p and Wc is set to 6 μm, which is set sufficiently larger than 4.5 μm which exceeds the maximum set thickness of the liquid crystal layer described later.
It is preferable to have a margin of 20% or more in consideration of processing variations in manufacturing. Therefore, it is preferable that the margin be sufficiently larger than 5.4 μm.

Thus, the electric field component applied to the liquid crystal layer parallel to the substrate surface becomes larger than the electric field component in the direction perpendicular to the substrate surface, and it is possible to suppress an increase in the voltage for driving the liquid crystal. The maximum value of the electrode width Wp, Wc of each electrode is
It is preferable that the distance be smaller than the distance L between the pixel electrode PX and the counter electrode CT.

This is because, if the distance between the electrodes is too small, the curvature of the lines of electric force becomes severe, and the region where the electric field component perpendicular to the substrate surface is larger than the electric field component parallel to the substrate surface is increased. This is because an electric field component parallel to the above cannot be efficiently applied to the liquid crystal layer. Therefore, the pixel electrode PX and the counter electrode C
The interval L between T needs to be larger than 7.2 μm if the margin is 20%. In this embodiment, the diagonal is about 1
Since the pixel pitch is about 60 μm because the resolution is 4.5 cm (5.7 inches) and the resolution is 640 × 480 dots, the distance L> 7.2 μm by dividing the pixel into two.
Was realized.

The electrode width of the video signal line DL is set to 8 μm, which is slightly wider than the pixel electrode PX and the counter electrode CT in order to prevent disconnection, and the interval between the video signal line DL and the counter electrode CT is short-circuited. In order to prevent this, an interval of about 1 μm is provided, a video signal line DL is formed on the upper side of the gate insulating film, and a counter electrode CT is formed on the lower side.

On the other hand, the electrode interval between the pixel electrode PX and the counter electrode CT changes depending on the liquid crystal material used. this is,
Since the electric field strength that achieves the maximum transmittance varies depending on the liquid crystal material, the electrode spacing is set according to the liquid crystal material, and within the range of the maximum amplitude of the signal voltage set by the withstand voltage of the video signal driving circuit (signal side driver) used. , So that the maximum transmittance can be obtained. When a liquid crystal material described later is used, the electrode interval is about 15 μm.

In this configuration example, a black matrix BM is formed on the gate line GL, the counter voltage signal line CL, the thin film transistor TFT, the drain line DL, and between the drain line DL and the counter electrode CT in plan view.

FIG. 8 is a sectional view of the thin film transistor TFT taken along the line FF in FIG. 7, and FIG. 9 is a sectional view of the storage capacitor Cstg taken along the line GG in FIG.

Referring to FIGS. 7 to 9, in the thin film transistor TFT, when a positive bias is applied to the gate electrode GT, the channel resistance between the source and the drain becomes small, and when the bias is made zero, the channel resistance becomes small. Work to be bigger.

The thin film transistor TFT has a gate electrode G
T, gate insulating film GI, i-type (intrinsic: intrinsic
c, an i-type semiconductor layer AS made of amorphous silicon (Si not doped with a conductivity type determining impurity), a pair of source electrode SD1, and a drain electrode SD2.

It should be understood that the source and the drain are originally determined by the bias polarity between them, and in the circuit of this liquid crystal display device, the polarity is inverted during the operation, and therefore, it should be understood that the source and the drain are switched during the operation. However, in the following description, one is fixed and the other is fixed as a drain for convenience.

The gate electrode GT is formed continuously with the scanning signal line GL (see FIG. 7), and is configured so that a partial area of the scanning signal line GL becomes the gate electrode GT.
The gate electrode GT is a portion exceeding the active region of the thin film transistor TFT, and is formed larger than that so as to completely cover the i-type semiconductor layer AS (as viewed from below).

Thus, in addition to the role of the gate electrode GT, the gate electrode GT is designed so that external light and backlight do not hit the i-type semiconductor layer AS. In this example, the gate electrode GT is formed of a single-layer conductive film g1. As the conductive film g1, for example, an aluminum (Al) film formed by sputtering is used, and an anodic oxide film AOF of Al is provided thereon.

The scanning signal line GL shown in FIG.
It is composed of The conductive film g1 of the scanning signal line GL is formed in the same manufacturing process as the conductive film g1 of the gate electrode GT, and is integrally formed. This scanning signal line GL
To apply a gate voltage Vg from an external circuit to the gate electrode GT.
To supply.

Further, an anodic oxide film AOF of Al is also provided on the scanning signal line GL. The portion that intersects with the video signal line DL is made thin to reduce the probability of short-circuit with the video signal line DL, and is made bifurcated so that even if it is short-circuited, it can be separated by laser trimming.

The counter electrode CT shown in FIG.
It is composed of a conductive film g1 of the same layer as T and the scanning signal line GL. Also, an anodic oxide film AOF of Al is formed on the counter electrode CT.
Is provided. The counter electrode CT is an anodic oxide film AOF
, So that even if they are brought as close as possible to the video signal lines, they will not be short-circuited.

Further, they may be configured to cross each other. The counter electrode CT is configured to apply a counter voltage Vcom. In this embodiment, the counter voltage Vc
om is a potential lower than an intermediate DC potential between the minimum level drive voltage Vdmin and the maximum level drive voltage Vdmax applied to the video signal line DL by a feedthrough voltage ΔVs generated when the thin film transistor element TFT is turned off. However, if you want to reduce the power supply voltage of the integrated circuit used in the video signal drive circuit to about half,
An AC voltage may be applied.

The counter voltage signal line CL is formed of the conductive film g1. The conductive film g1 of the counter voltage signal line CL is formed in the same manufacturing process as the conductive film g1 of the gate electrode GT, the scanning signal line GL, and the counter electrode CT, and is formed integrally with the counter electrode CT.

The counter voltage Vcom is supplied from an external circuit to the counter electrode CT through the counter voltage signal line CL. or,
An anodic oxide film AOF of Al is also provided on the counter voltage signal line CL. The portion that intersects with the video signal line DL is thinned to reduce the probability of a short circuit with the video signal line DL, as in the case of the scanning signal line GL. It can be bifurcated.

The insulating film GI is used as a gate insulating film for applying an electric field to the semiconductor layer AS together with the gate electrode GT in the thin film transistor TFT. Insulating film GI
Are formed above the gate electrode GT and the scanning signal line GL.

As the insulating film GI, for example, plasma CVD
The silicon nitride film formed by
It is formed to a thickness of nm (240 nm in this embodiment).

The gate insulating film GI is formed in the matrix portion A
R is formed so as to surround the entirety of R, and the peripheral portion is removed so as to expose the external connection terminals DTM and GTM. Also,
The insulating film GI also contributes to electrical insulation between the scanning signal lines GL and the counter voltage signal lines CL and the video signal lines DL.

The i-type semiconductor layer AS is made of amorphous silicon.
It is formed with a thickness of 20 to 220 nm (in this example, a thickness of about 200 nm). The layer d0 is an N (+) type amorphous silicon semiconductor layer doped with phosphorus (P) for ohmic contact, and has an i-type semiconductor layer AS below and a conductive film d1 (d2) above. It is left only where you do.

The i-type semiconductor layer AS is also provided between the scanning signal line GL and the intersection of the opposing signal line CL and the video signal line DL. The i-type semiconductor layer AS at the intersection reduces a short circuit between the scanning signal line GL and the opposing signal line CL and the video signal line DL at the intersection.

Each of the source electrode SDI and the drain electrode SD2 is composed of a conductive film d1 in contact with the N (+) type semiconductor layer d0 and a conductive film d2 formed thereon.

The conductive film d1 is formed to have a thickness of about 50 to 100 nm (about 60 nm in this embodiment) using a chromium (Cr) film formed by sputtering. Since the stress increases when the Cr film is formed to have a large thickness, the Cr film has a thickness of 200 nm.
It is formed in a range that does not exceed a certain thickness. Cr film is N
To improve the adhesion to the (+) type semiconductor layer d0,
2 is used for the purpose of a so-called barrier layer that prevents Al from diffusing into the N (+) type semiconductor layer d0.

As the conductive film d1, a refractory metal (Mo, Ti, Ta, W) film or a refractory metal silicide (MoSi ₂ , TiSi ₂ , TaSi ₂ , WSi ₂ ) film may be used in addition to the Cr film. .

The conductive film d2 has a thickness of 30
It is formed to a thickness of 0 to 500 nm (about 400 nm in this embodiment). The Al film has a smaller stress than the Cr film and can be formed to have a large thickness.
It has functions of reducing the resistance values of D1, the drain electrode SD2, and the video signal line DL, and ensuring the step over caused by the gate electrode GT and the i-type semiconductor layer AS (to improve the step coverage).

After patterning the conductive films d1 and d2 with the same mask pattern, the N (+) type semiconductor layer d0 is removed using the same mask or using the conductive films d1 and d2 as a mask. That is, the i-type semiconductor layer AS
The remaining N (+) type semiconductor layer d0 is a conductive film d1,
Portions other than the conductive film d2 are removed by self-alignment.
At this time, since the N (+)-type semiconductor layer d0 is etched so as to completely remove its thickness, the i-type semiconductor layer A is removed.
Although the surface portion of S is also slightly etched, its degree may be controlled by the etching time.

The video signal line DL has the second conductive film d2 and the third conductive film d in the same layer as the source electrode SD1 and the drain electrode SD2.
3. The video signal line DL is formed integrally with the drain electrode SD2.

The pixel electrode PX is composed of the second conductive film d2 and the third conductive film d3 in the same layer as the source electrode SD1 and the drain electrode SD2.
It is composed of The pixel electrode PX is connected to the source electrode SD
1 and are formed integrally.

The pixel electrode PX is a thin film transistor TFT
An end opposite to the end connected to the counter voltage signal line CL is formed to overlap with the opposite voltage signal line CL. As is apparent from FIG. 9, this superposition is performed by using the pixel electrode PX as one electrode PL2 and the counter voltage signal line CL as the other electrode PL.
A storage capacitance (capacitance element) Cstg is set to 1. The dielectric film of the storage capacitor Cstg is an insulating film GI used as a gate insulating film of the thin film transistor TFT.
And an anodic oxide film AOF.

As shown in FIG. 7, the storage capacitor Cstg is formed in the conductive film g1 of the counter voltage signal line CL in plan view.

In this case, the storage capacitor Cstg is made of Al because the material of the electrode positioned below the insulating film GI is formed of Al and the surface thereof is anodized. It is possible to obtain a storage capacitor which is less likely to cause adverse effects due to a point defect (short-circuit with an electrode positioned on the upper side) caused by a so-called hillock or the like.

FIG. 10 is a schematic explanatory diagram of a driving circuit of a liquid crystal display device according to the present invention. The liquid crystal display device is composed of a group of multiple pixels in which the image display section is arranged in a matrix, and each pixel is configured to independently control the transmitted light from the backlight arranged behind the liquid crystal display substrate Have been.

Lower Substrate Constituting Liquid Crystal Panel (SUB1)
Above, the gate signal line GL and the counter voltage signal line CL, which extend in the x direction (row direction) in the effective display area AR and are juxtaposed in the y direction (column direction), are respectively insulated and extend in the y direction. Thus, drain signal lines DL arranged in parallel in the x direction are formed.

Here, a unit pixel is formed in a rectangular area surrounded by each of the gate signal line GL, the counter voltage signal line CL, and the drain signal line DL.

The liquid crystal panel is provided with a vertical scanning circuit V and a video signal driving circuit H as external circuits, and the vertical scanning circuit V sequentially supplies a scanning signal (voltage) to each of the gate signal lines GL. The video signal drive circuit H supplies a video signal (voltage) to the drain signal line DL in accordance with the timing.

The vertical scanning circuit V and the video signal driving circuit H are supplied with power from the liquid crystal driving power supply circuit 3 and input image information from the CPU 1 after being divided into display data and control signals by the controller 2 respectively. It is supposed to be.

FIG. 11 is a driving waveform diagram of the liquid crystal display device of the present invention. In the figure, the counter voltage is a binary AC rectangular wave of VCH and VCL, and the scanning signal VG is synchronized with the rectangular wave.
(I-1) The non-selection voltage of VG (i) is changed by two values of VCH and VCL every scanning period. The amplitude width of the counter voltage and the amplitude value of the non-selection voltage are the same.

The video signal voltage is a voltage obtained by subtracting half the amplitude of the counter voltage from the voltage to be applied to the liquid crystal layer.

The counter voltage may be DC, but by converting it to AC, the maximum amplitude of the video signal voltage can be reduced, and a video signal drive circuit (signal side driver) having a low withstand voltage can be used.

FIG. 12 is an exploded perspective view showing each component of the liquid crystal display device which has been modularized. SHD is a frame-like frame made of a metal plate (also referred to as a shield case or metal frame), WD is its display window, PNL is a liquid crystal panel, FMS is a surface light-shielding layer, SPS is a light diffusion plate, GLB is a light guide, and RFS. Denotes a reflector, BL denotes a fluorescent tube of a backlight, and MCA denotes a lower case (backlight case). The members are stacked in a vertical arrangement as shown in the figure to assemble a module MDL.

The whole module MDL is fixed by claws and hooks provided on the frame SHD.

The backlight case MCA comprises a cold cathode fluorescent lamp LP, a light diffusion plate SPS,
The cold cathode fluorescent tube LP has a shape for accommodating the light guide GLB and the reflection plate RFS, and is disposed on a side surface of the light guide GLB.
Is made uniform illumination light on the display surface by the light guide GLB, the reflection plate RFS, and the light diffusion plate SPS, and is emitted to the liquid crystal panel PNL side.

An inverter circuit board is connected to the cold cathode fluorescent tube LP, and serves as a power supply for the cold cathode fluorescent tube LP.

FIG. 13 is a perspective view of a notebook personal computer as an example of an electronic device on which the liquid crystal display device according to the present invention is mounted. The notebook computer (portable personal computer) includes a keyboard unit (main body unit) and a display unit connected to the keyboard unit by a hinge. The keyboard unit accommodates a keyboard and a signal generation function such as a host (host computer) and a CPU, and the display unit has a liquid crystal panel PNL, around which drive circuit boards PCB1 and PCB2, a control chip TCON and a CPU. A PCB 3 mounted with a connector CT or the like for connecting signals, an inverter power supply board serving as a backlight power supply, and the like are mounted.
This liquid crystal panel PNL has the alignment film described in each of the above embodiments.

Then, various circuit boards PCB1, PCB2, PCB3, an inverter power supply board, and a backlight are integrated with the liquid crystal panel PNL and mounted as a liquid crystal display module MDL.

[0120]

As described above, according to the present invention,
The light leakage around the effective display area of the liquid crystal display device can be reduced, the black matrix is not exposed on the edge of the substrate of the liquid crystal panel, and the light shielding performance around the effective display area is the same as when there is no adhesive tape. Or a liquid crystal display device capable of displaying high-quality images with improved antistatic properties and EMI countermeasures can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a principal part schematically showing a configuration of a first embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a cross-sectional view schematically showing the entire configuration of the liquid crystal display device of FIG.

FIG. 3 is a sectional view of an essential part of the liquid crystal display device, schematically illustrating the effect of the first embodiment of the liquid crystal display device according to the present invention.

FIG. 4 is a sectional view schematically showing a main part of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view schematically showing a main part of a liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view schematically showing a main part of a liquid crystal display device according to a fifth embodiment of the present invention.

FIG. 7 is a plan view showing the periphery of one pixel of the in-plane switching mode color liquid crystal display device to which the present invention is applied.

8 is a cross-sectional view of the thin-film transistor TFT taken along the line FF in FIG. 7;

9 is a diagram showing a storage capacitance Cstg along the line GG in FIG. 7;
FIG.

FIG. 10 is a schematic explanatory diagram of a driving circuit of a liquid crystal display device according to the present invention.

FIG. 11 is a driving waveform diagram of the liquid crystal display device of the present invention.

FIG. 12 is an exploded perspective view showing each component of a modularized liquid crystal display device.

FIG. 13 is a perspective view of a notebook personal computer as an example of an electronic device on which the liquid crystal display device according to the present invention is mounted.

FIG. 14 is a cross-sectional view of a principal part explaining an example of an assembling structure of a liquid crystal panel and a frame of a conventional liquid crystal display device.

[Explanation of symbols]

 SHD frame BAT Adhesive tape SUB1 Lower substrate SUB2 Upper substrate BM Black matrix SL Seal material BL Backlight FSM Surface light-shielding layer LC Liquid crystal layer FIL Color filter TCL Transparent conductive film.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G09F 9/00 315 G09F 9/00 315B 321 321D 348 348E 9/35 320 9/35 320

Claims (8)

[Claims] A plurality of color filters partitioned by an inner light-shielding layer are provided on an inner surface of at least one of a pair of upper and lower substrates, the electrode group for selecting pixels and a wiring electrode group being provided on an inner surface of the other substrate. A liquid crystal panel having a liquid crystal layer sandwiched between opposing gaps of the pair of substrates, and a driving circuit for applying a pixel selection voltage to the electrode group via the wiring electrode group. The inner light-shielding layer of the other substrate is also formed around an effective display area of the substrate, and on the outer surface of the other substrate, at least from the end face of the substrate to the outer end face of the inner light-shielding layer. A liquid crystal display device comprising an outer light-shielding layer formed in a region reaching a corresponding position. 2. An image display apparatus according to claim 1, further comprising: a pixel selecting electrode group, a wiring electrode group, and a switching element group provided only on an inner surface of one of the pair of substrates, and a plurality of colors of pixels divided by an inner light shielding layer on an inner surface of the other substrate. A liquid crystal panel having a color filter, a liquid crystal layer sandwiched between opposed gaps between the pair of substrates, and a drive circuit for selectively applying a pixel selection voltage to the switching element group via the wiring electrode group. In the liquid crystal display device provided at least, the inner surface light-shielding layer of the other substrate is also formed around the effective display area of the substrate, and the outer surface of the other substrate is at least the inner surface from an end surface of the substrate. A liquid crystal display device comprising an outer light-shielding layer formed in a region reaching a position corresponding to an outer peripheral end face of the light-shielding layer. 3. A frame provided with a window having an inner end on an outer periphery of an effective display area of the liquid crystal panel, wherein the inner light-shielding layer of the other substrate is also formed around the effective display area of the substrate. 2. An outer light-shielding layer formed on an outer surface of the other substrate in a region from an inner end of a window of the frame to a position corresponding to an outer-side end surface of the inner light-shielding layer. Or the liquid crystal display device according to 2. 4. The liquid crystal display device according to claim 1, wherein the surface light-shielding layer is formed of a metal material, and the inner surface light-shielding layer is formed of an organic material. 5. The liquid crystal display device according to claim 1, wherein a transparent conductive film is formed on the entire surface of the upper substrate so as to cover the surface light-shielding layer. 6. The liquid crystal display device according to claim 1, wherein said surface light-shielding layer is formed above said transparent conductive layer. 7. The liquid crystal display device according to claim 5, wherein said surface light-shielding layer is formed of a metal material. 8. The liquid crystal display device according to claim 5, wherein said transparent conductive layer is electrically connected to said frame.