JP4522177B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device with a narrow frame used for a notebook personal computer or a display.

A conventional general liquid crystal panel is formed by bonding a TFT substrate having a TFT element and a CF substrate having a color filter together with a sealing material, dividing it into a desired size, and then injecting a liquid crystal material between the two substrates. FIG. 5 shows a cross-sectional view of a conventional liquid crystal panel. As shown in this figure, in the TFT substrate 1, a gate wiring 12, an insulating layer 13 and a source wiring 14 are formed on a glass substrate 11, and a pixel electrode (ITO film) 16 is formed thereon via an interlayer insulating layer 15. Being done. An alignment film 17 is formed thereon. On the other hand, in the CF substrate 2, red (R), green (G), and blue (B) color filters 23 are regularly formed on a glass substrate 21, and a black matrix for light shielding is provided between the color filters. (BM) 22 is formed. Further, a counter electrode film 24 and an alignment film 25 are formed thereon. And this TFT substrate 1 and the CF substrate 2 are bonded by the sealing member (not shown), the liquid crystal material 7 is injected between the substrates.

  As shown in FIG. 6, the TFT substrate 1 is provided with a display region 10 in which a gate line 12 and a source line 14 intersect each other. The gate line 12 and the source line 14 are formed so as to extend beyond the display area 10, and a gate voltage is input to the gate line 12 via terminal pads 18 and 19 provided in the terminal area outside the display area 10. The source voltage is input to 14. On the other hand, on the CF substrate 2, a counter electrode film 24 is formed on almost the entire surface of the glass substrate 21, and overhang portions 241 are formed in places on the outer periphery of the counter electrode film 24. When the CF substrate 2 and the TFT substrate 1 are bonded together, the common paste 3 applied on the ITO pad portion provided on the TFT substrate 1 and the overhanging portion 241 come into contact with each other, whereby the CF substrate 2 The counter electrode film 24 is electrically connected to the TFT substrate 1. The overhanging portion 241 of the counter electrode film 24 needs to be formed with a margin in consideration of an accuracy error when the common paste 3 is applied to the TFT substrate 1.

  On the other hand, although the display screen has been increasing in size in recent years, the external dimensions of the apparatus tend to be reduced, contrary to the increase in the display screen. In addition, the number of display pixels has increased and the number of wirings has increased dramatically for higher definition of screen display. For this reason, many terminal pads must be formed in the terminal region of the device that has become narrower than before, and the distance between the terminal pads becomes very narrow, which is connected to the terminal pads formed in the frame region. Wiring intervals have also become narrower.

  For this reason, as shown in FIG. 7, contact holes 4 a formed at both ends of the diagonal wiring portion 141 on the TFT substrate may be located in the opposing region of the counter electrode film 24 of the CF substrate 2. Here, a schematic view of the contact hole 4a is shown in FIG. The contact hole 4a is a hole that penetrates the insulating layer 13, the source wiring 14, and the insulating layer 15 so as to expose a part of the lowermost gate wiring 12, and the hole is covered with the ITO film 5. Yes. As a result, the oblique wiring portion 141 (shown in FIG. 7) can transmit an electrical signal through the two wirings of the gate wiring 12 and the source wiring 14, and unless both the gate wiring 12 and the source wiring 14 are disconnected. An electric signal is transmitted, and disconnection failure in the oblique wiring portion 141 (shown in FIG. 7) is effectively prevented.

  However, as shown in FIG. 9, when the contact hole 4 a having the above structure is located in the opposing region of the counter electrode film 24 of the CF substrate 2, the conductive foreign matter 6 such as metal shavings resulting from the manufacturing process is contacted. When sandwiched between the hole 4a and the counter electrode film 24, a short circuit occurs in this portion, the wiring is burned, and a display defect occurs.

As a method for preventing leakage due to the conductive foreign matter 6 between the TFT substrate 1 and the CF substrate 2, for example, in Patent Document 1, the wiring layer of one substrate is covered with an insulating film, and the wiring layer, the counter electrode film, There has been proposed a technique for preventing leakage due to conductive foreign matter.
WO98 / 09191 (Claims, pages 5-7, FIG. 1)

  However, in the proposed technique of Patent Document 1, since an insulating film is formed on the surface of the wiring layer, a new process must be added to the conventional production process, and a decrease in productivity is expected. The technique proposed in Patent Document 1 is intended to prevent leakage due to conductive foreign matter in the display region, and includes a contact hole in the TFT substrate and a counter electrode film in the CF substrate in the non-display region. It does not prevent leakage due to the conductive foreign matter.

  The present invention has been made in view of such conventional problems, and the object thereof is to provide a conductive layer sandwiched between the contact hole of the TFT substrate and the counter electrode film of the CF substrate without causing a reduction in productivity. It is an object of the present invention to provide a liquid crystal display device in which no leakage occurs due to sexual foreign substances.

In order to achieve the above object, in the liquid crystal display device of the present invention, in a liquid crystal display device having a frame width of 3.5 mm or less outside the display region, a contact hole formed outside the display region of one substrate in plan view as the overhanging portion overhanging the display area outside to electrical connection through said one substrate and the paste of the formed on the other substrate conductive film do not overlap, one of the protruding portion The part opposite to the display area was cut out with the paste in between .
The “frame width” in the present invention means the width between the display area and the terminal area as shown in FIG.

  Here, from the viewpoint of completely preventing a short circuit caused by the conductive foreign matter, it is preferable to form the conductive film at a position 500 μm or more away from the outer periphery of the contact hole in plan view.

  In the liquid crystal display device of the present invention, the contact hole formed outside the display region of one substrate and the conductive film formed on the other substrate are not overlapped in plan view. It is possible to effectively suppress a short circuit caused by a foreign object sandwiched between them. This suppresses display defects and improves the yield of the liquid crystal display device.

  When the conductive film is formed at a position 500 μm or more away from the outer periphery of the contact hole in plan view, a short circuit caused by the conductive foreign matter can be completely prevented.

  Hereinafter, the liquid crystal display device according to the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments.

  FIG. 1 is a plan view of the outside of a display area of a TFT substrate showing an embodiment of a liquid crystal display device of the present invention. A plurality of terminal pads 19 are formed at predetermined intervals in the terminal region on the outer peripheral edge of the TFT substrate 1. A wiring 14 extending from the display area is connected to the terminal pad 19 through the contact holes 4a and 4b while being refracted. In a plan view, a region is secured between the series of contact holes 4a for the extension portion 241 of the counter electrode film (conductive film, broken line and colored) 24 formed on the CF substrate 2 to enter. . Then, when the TFT substrate 1 and the CF substrate 2 are bonded together, the protruding portion 241 of the counter electrode film 24 is located in this region.

  The overhanging portion 241 of the counter electrode film 24 is normally symmetrical. However, in such a normal shape, when it overlaps the contact hole 4a in plan view, the portion overlapping the contact hole 4a is cut out. The contact hole 4a and the counter electrode film 24 were not overlapped in plan view. At this time, as shown in FIG. 2, it is recommended that the distance between the outer periphery of the contact hole 4a and the counter electrode film 24 (X, Y in FIG. 2) be 500 μm or more in plan view. This is because it is possible to reliably prevent a short circuit due to conductive foreign matter between the contact hole 4a and the counter electrode film 24.

  FIG. 3 shows another embodiment. In the liquid crystal display device of FIG. 3, in order to eliminate the overlap with the contact hole 4a formed in the TFT substrate 1, the right side portion of the overhanging portion 241 of the counter electrode film 24 of the CF substrate 2 is extended from the outer periphery of the contact hole 4a. Notched so as to be 500 μm or more apart.

The counter electrode film 24 having such a shape may be formed on the CF substrate 2 as follows, for example. First, a BM layer is formed on a glass substrate. A Cr layer to be a BM layer is formed on the entire surface of the glass substrate by a sputtering apparatus, and a photoresist (negative type) is applied thereon. Then, a photomask having a predetermined pattern of holes formed thereon is placed and irradiated with ultraviolet rays to cure the photoresist. Next, the resist softened portion that has not been irradiated with ultraviolet rays is removed with a developer, and development is performed. Thereafter, unnecessary Cr is removed with an etchant (wet etching) or reacted by gas discharge under reduced pressure to be removed in a gaseous state (dry etching). Then, the cured photoresist is removed with a stripping solution, and a BM layer is formed on the glass substrate.

  Next, a red (R) colorant is applied to the entire surface of the glass substrate on which the BM layer is formed, and then a photoresist (negative type) is applied thereon. Then, a mask is placed and irradiated with ultraviolet rays. Next, the resist in the softened portion that has not been irradiated with ultraviolet rays is removed with an alkaline solution. At this time, the colored layer in that portion is also removed at the same time. Thereafter, the photoresist is peeled off to obtain a predetermined R pixel pattern. The same process is repeated to form a G pixel pattern and a B pixel pattern.

  Next, a counter electrode film is formed directly on the color filter layer or on the overcoat layer by a sputtering apparatus or the like. Since this counter electrode film functions as a common electrode of the liquid crystal pixel, it is formed on the entire surface of the color filter layer. As described above, the counter electrode film is formed on the portion facing the contact hole formed outside the display area of the TFT substrate. Avoid forming. In order to form the counter electrode film having such a shape, sputtering may be performed in a state where a metal mask having an opening in the shape of the counter electrode film to be formed is applied to the CF substrate. The thickness of the counter electrode film is preferably about 1000 to 2000 mm.

  Then, an alignment film is formed on the counter electrode film of the CF substrate. The alignment film is formed by dissolving polyimide resin or the like in a solvent and printing it on a glass substrate surface with a precision rubber plate or applying it by a spinner method. The thickness of the alignment film is preferably about 500 to 1000 mm.

It is the elements on larger scale of the TFT substrate of the liquid crystal display device which concerns on this invention. It is an enlarged view of the TFT substrate of FIG. It is an enlarged view of a TFT substrate showing another embodiment. It is a top view of the TFT substrate which shows the frame area | region in this invention. It is a vertical sectional view showing an example of a liquid crystal display device. It is a general | schematic perspective view of a liquid crystal display device. It is the elements on larger scale of the TFT substrate of the conventional liquid crystal display device. It is a vertical sectional view of a contact hole. It is a vertical sectional view when conductive foreign matter is sandwiched between a counter electrode film and a contact hole.

Explanation of symbols

1 TFT substrate 2 CF substrate 3 Common paste 10 Display region 4a, 4b Contact hole 19 Terminal pad 24 Counter electrode film (conductive film)
141 Diagonal wiring part 241 Overhang part 242 Notch part

Claims (2)

In the liquid crystal display device whose frame width outside the display area is 3.5 mm or less,
In plan view, the contact hole formed outside the display area of one substrate and the conductive film formed on the other substrate are electrically connected to the one substrate via the paste. A liquid crystal display device , wherein a portion of the protruding portion opposite to the display area is cut out with the paste interposed therebetween so that the protruding portion does not overlap.   The liquid crystal display device according to claim 1, wherein a conductive film is formed at a position separated from the outer periphery of the contact hole by 500 μm or more in plan view.

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