JPH0682804A - Active matrix driving type liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide the liquid crystal display device which is inexpensive and has high quality and high sealing strength by providing the outer periphery of a screen display region with a metallic light sliding film having saw tooth- shaped electrodes connected to a power source and conducting to a ITO film. CONSTITUTION:The metallic light shielding film 12 has the shape provided with a central part 12a covering the entire surface of the screen display region 1a of the outside shape indicated by an alternate long and short dash line and the many saw tooth-shaped electrodes 12b around this part. The saw tooth- shaped electrodes 12b exist between a sealing material and a transparent substrate 11 and are connected to external electrodes. The sealing material is securely adhered to the transparent substrate 11 exposed from between the saw tooth-shaped electrodes 12b and the saw tooth-shaped electrodes 12b to securely integrate the substrate to the entire part of the display device. An ITO thin film 14 is formed via color filter layers of three colors on the metallic light shielding film 12 at need and is conducted to the metallic light shielding film 12 between the color filter layers and the color filter layers or in the outer peripheral part where the color filter layers do not exist.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix drive type liquid crystal display device. More specifically, the present invention relates to a large-sized liquid crystal display device having a large number of pixels and capable of high-density and high-quality display, and moreover, to an active matrix drive type liquid crystal display device in which the whole is firmly integrated.

[0002]

2. Description of the Related Art In general, an active matrix drive type liquid crystal display device has a front substrate 1, a rear substrate 2 and a front substrate 1 and a rear substrate 2 in a seal region on the outer periphery as shown in a schematic sectional view of FIG. It is composed of a sealing material 3 which is integrated with each other and a liquid crystal substance 4 which is enclosed in a region surrounded by the sealing material 3 and the front substrate 1 and the rear substrate 2. A screen display area 1a composed of a large number of pixels is provided in the substantially central portion, and transmission / non-transmission of display light is controlled for each pixel, and an image is displayed by the transmissive portion and the non-transmissive portion. .

The front substrate 1 of this active matrix drive type liquid crystal display device is formed by laminating layers having respective functions on a transparent substrate 11 such as a glass plate. The metal light-shielding film 12 is laminated on the lattice-shaped portion (inter-pixel portion) between the above-mentioned pixels, and the ambient light transmitted through the inter-pixel portion is prevented to improve the contrast of the screen.

When the active matrix drive type liquid crystal display device is a color liquid crystal display device displaying a color image, the transparent substrate 11 is provided with display light of a desired color (for example, red, green and blue light). Optical filter layers 13R, 13G, and 13B that are colored in three primary colors are laminated on respective pixel portions. Optical filter layers 13R, 13G, 13
B and the metal light-shielding film 12 may be laminated in any order, but the optical filter layers 13R and 13R and
The edges of G and 13B and the edges of the metal light-shielding film 12 often overlap with each other, and in order to prevent the reflected light of the metal light-shielding film 12 from being colored and lowering the contrast of the displayed image, the metal light-shielding film 12 is covered. It is common to provide optical filter layers 13R, 13G, 13B.

The color filter layers 13R, 13
An ITO thin film 14 formed by a sputtering method is provided on the entire surface of the screen display region on the G, 13B or metal light shielding film 11, and a rubbing treatment is performed on the surface side of the front substrate 1 in contact with the liquid crystal substance 4. An alignment film 15 for aligning the liquid crystal substance 4 is provided.

On the other hand, the back substrate 2 is also formed by laminating layers having respective functions on a transparent substrate 21 such as a glass plate. First, at the pixel portion, a liquid crystal material is formed between the ITO thin film 14 and the pixel portion. 4 is provided with an electrode 22 for applying a voltage, and a control element 23 such as a transistor for driving the electrode 22 for each pixel is provided in the inter-pixel portion.
In addition, an alignment film 24 that aligns the liquid crystal substance 4 by rubbing the surface of the back substrate 2 that contacts the liquid crystal substance 4.
Is provided.

In this active matrix drive type liquid crystal display device, a power source is connected to the ITO thin film 14 to keep the ITO thin film 14 at a constant potential, and
A voltage is applied to the electrode 22 selected according to the signal, and the liquid crystal material 4 is driven by the application of this voltage to transmit the display light.
The image is displayed by controlling opacity.

Incidentally, both the front substrate 1 and the rear substrate 2 are generally provided with a polarizing film, but they are not shown in this figure.

The metal light-shielding film 12 and the ITO thin film 14 have a shape as shown in FIG. 4, and the metal light-shielding film 12 has a screen display area whose outline is shown by a dashed line in FIG. It consisted of a frame-shaped area. In addition, the ITO thin film 14 has a shape that covers the entire surface of the metal light-shielding film 12 forming portion, and has an electrode terminal 14a connected to the power source for keeping the ITO thin film 14 at a constant potential in the corner thereof. The terminal 14a passes through the sealing area and is connected to the power source located outside the sealing area. The ITO thin film 14 having such a shape is used for the substrate 11
The shape opposite to the shape of the ITO thin film 14 (ITO thin film 1
It was formed by a method in which a metal mask having a shape corresponding to a negative pattern (where 4 shapes are positive patterns) is overlapped, ITO is sputtered, and this ITO is removed together with the metal mask.

[0010]

By the way, in the liquid crystal display device of this type, the number of pixels is increased year by year to display a high-quality and high-density image and the display screen tends to be large. . Since it is necessary to lower the transfer resistance of the ITO thin film 14 in response to the increase in the number of pixels and the enlargement of the display screen, as shown in FIG. 5, a large number of comb teeth are formed around the ITO thin film 14. The electrode terminal 14a is provided,
A method has been proposed in which the power source is connected to a large number of comb-teeth-shaped electrode terminals 14a to reduce the transfer resistance and stabilize the potential of the ITO thin film 14.

However, if the ITO thin film 14 having such a shape is to be formed by the sputtering method using a metal mask as in the conventional case, the charged ITO ejected from the target by ions or the like adheres to the metal mask. In some cases, the metal mask of the lever is electrically charged, and the metal light-shielding film 12 and the metal mask are discharged at a portion where the metal mask overlaps with each other to damage the shape of the metal light-shielding film 12. In order to avoid this, as shown in FIG. 6, a method has been proposed in which the insulating sheet 6 is interposed between the metal light-shielding film 12 and the metal mask 5, but sputtering is performed. There is a problem in that the mask 5 and the metal light-shielding film 12 become distant, ITO wraps around the gap between them, the pattern of the ITO thin film 14 is blurred, and the film spreads, so that the sealing strength in the sealing region decreases.

There is also known a method in which the above ITO thin film is provided on the entire surface and then patterned by photolithography, but the photolithography process is required, which inevitably results in high cost.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has an active-matrix drive type which has a large-sized screen which can be manufactured at low cost and can display a high-quality image, and has a high seal strength in the seal area. An object is to provide a liquid crystal display device.

[0014]

That is, according to the present invention, there is provided a transparent substrate having a screen display region in a substantially central portion thereof, a metal light-shielding film provided in an inter-pixel portion of the screen display region of the transparent substrate, and the transparent substrate. An ITO thin film provided on the entire screen display area of the substrate and connected to a power supply; a front substrate provided on the ITO thin film and having an alignment film for aligning liquid crystals; and an electrode capable of applying a voltage to each pixel A back substrate, a sealing material that integrates the front substrate and the back substrate at the outer periphery of the screen display area, and a liquid crystal substance enclosed in a region surrounded by the sealing material, the front substrate and the back substrate, In an active matrix drive type liquid crystal display device in which a voltage is applied between an ITO thin film and an electrode to control transmission / non-transmission of display light for each pixel to display an image, the metal light-shielding film has a screen display area. It has a comb-shaped electrode connected to the power supply in the outer periphery of, and the metal light-shielding film and the ITO
The thin film is electrically conductive.

[0015]

According to the present invention, since the ITO thin film is connected to the power source through the metal light-shielding film, the comb-teeth shape required for stabilizing the potential of the ITO thin film in a large screen having high density pixels is provided. It is not necessary to provide many electrodes on the ITO thin film,
Therefore, deterioration of the seal strength due to blurring of the ITO thin film does not occur.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. In the active matrix driving type liquid crystal display device according to the embodiment of the present invention, the shape of the metal light shielding film of the front substrate and the IT
It is the same as the conventional example except for the shape of the O thin film, and its schematic sectional view is shown in FIG. The shape of the metal light shielding film and the shape of the ITO thin film of the front substrate according to the embodiment of the present invention are shown in FIG.
Is shown in.

That is, in FIG. 1, reference numeral 12 denotes a metal light-shielding film, which has a central portion 12a which covers the entire surface of the screen display area 1a whose outer shape is shown by the alternate long and short dash line in FIG. It has a shape including the electrode 12b. The comb-teeth-shaped electrode 12 b is the sealing material 3 described above.
It is located between the transparent substrate 11 and the transparent substrate 11 and is connected to an external electrode. Then, the sealing material 3 is firmly adhered to the comb-shaped electrodes 12b and the transparent substrate 11 exposed between the comb-shaped electrodes 12b to firmly integrate the entire display device.

The metal light-shielding film 12 is formed by forming a thin film of a metal such as chromium by a method such as vacuum deposition or sputtering, applying a photosensitive resin, exposing and developing, and then etching. You can Alternatively, it may be formed by forming a thin film through a mask having a pattern opposite to the metal light-shielding film pattern and then removing the mask.

Further, in FIG. 1, reference numeral 14 denotes an ITO thin film, which is formed on the metal light-shielding film 12 through three color filter layers if necessary. When the color filter layer does not exist, of course, even when the color filter layer exists, it is electrically connected to the metal light-shielding film 12 between the color filter layers or in the outer peripheral portion where the color filter layer does not exist. .

The ITO thin film 14 can be formed by a method similar to the conventional method. That is, as shown in FIG. 2, a metal mask 5 having a pattern opposite to the ITO thin film pattern is used, an insulating sheet is arranged between the metal mask 5 and the transparent substrate 11, and ITO is sputtered. It suffices to remove the unnecessary part of the ITO together with the mask. In the front substrate 1 shown in the figure, this ITO thin film 1
Reference numeral 4 denotes a central region 1 that covers the central portion 12a of the metal light shielding film 12.
In addition to 4a, it has a shape having electrodes 14b at three corners, and this electrode 14b is connected to an external power source like the electrode 12b of the metal light-shielding film 12. This electrode 14
Blurring of the ITO pattern occurs when the ITO thin film 14 is formed at the corner where b exists, but the blurring in this area is within the allowable range. Moreover, you may apply the ITO thin film 14 of such a shape without the electrode 14b of a corner part.

The ITO thin film 14 is composed of a large number of comb-teeth-shaped electrodes 12b of the metal light-shielding film 12 and the electrodes 14 at the corners.
Since it is connected to the external power supply through all of b, the ITO
A uniform potential can be stably maintained over the entire thin film 14.

[0022]

According to the present invention, it is not necessary to provide a large number of comb-teeth-shaped electrodes on the ITO thin film, and therefore, the deterioration of the seal strength due to the blurring of the ITO thin film does not occur, and the pixel has a high density. Since it is possible to stabilize the potential of the ITO thin film on a large screen, it is possible to firmly integrate the entire high quality liquid crystal display device.

[Brief description of drawings]

FIG. 1 is a plan view of a front substrate according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a manufacturing process of a front substrate according to an embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of an active matrix drive type liquid crystal display device.

FIG. 4 is a plan view of a conventional front substrate.

FIG. 5 is a plan view of a conventional front substrate.

FIG. 6 is an explanatory view showing a manufacturing process of a conventional front substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Front substrate 1a Screen display area 11 Transparent substrate 12 Metal light shielding film 12a Metal light shielding film central portion 12b Comb-shaped electrode 14 ITO thin film 14a ITO thin film central portion 12b ITO thin film electrode 2 Rear substrate 3 Sealing material 4 Liquid crystal substance

Claims (1)

[Claims] 1. A transparent substrate having a screen display region in a substantially central portion, a metal light-shielding film provided in an interpixel portion of the screen display region of the transparent substrate, and a transparent substrate provided on the entire screen display region of the transparent substrate, ITO thin film connected to power supply and this ITO
A front substrate that is provided on a thin film and that has an alignment film that aligns liquid crystals, a back substrate that has electrodes that can apply a voltage to each pixel, and the front substrate and the back substrate are integrated at the outer periphery of the screen display area. It is composed of a sealing material and a liquid crystal substance enclosed in a region surrounded by the sealing material, the front substrate and the rear substrate, and a voltage is applied between the ITO thin film and the electrode to prevent transmission / non-transmission of display light. In an active matrix drive type liquid crystal display device which controls each pixel to display an image, the metal light-shielding film has comb-teeth electrodes connected to the power source on the outer periphery of a screen display area, and An active matrix drive type liquid crystal display device characterized in that the ITO thin film is conductive.