JP3592706B2 - Active matrix liquid crystal display panel - Google Patents

Description

  The present invention relates to an active matrix type liquid crystal display panel, and more particularly to an active matrix type liquid crystal display panel called a horizontal electric field type.

An active matrix type liquid crystal display panel called a horizontal electric field type is provided with a display electrode on a surface of a transparent substrate which is disposed to face each other with a liquid crystal layer therebetween, corresponding to a unit pixel on one liquid crystal side. And a reference electrode, and light transmitted through the liquid crystal layer is modulated by an electric field generated in parallel with the transparent substrate between the display electrode and the reference electrode.
On the transparent substrate surface, a thin film transistor for each pixel and a scanning signal line for collectively turning on the thin film transistors arranged in the x direction, which are formed at a boundary portion of each pixel region, A video signal line for supplying a video signal to the display electrode via the formed thin film transistor, a reference signal line for supplying a reference signal to the reference electrode, and the like.
A liquid crystal display panel having such a configuration is described in detail in, for example, the following Patent Document.
In the liquid crystal display panel having such a configuration, the light-shielding film formed on the surface of the other transparent substrate on the liquid crystal layer side with the liquid crystal layer interposed therebetween is used as a video signal disposed adjacent to one transparent substrate surface. It has been essential to form it so as to sufficiently cover a region between the line and, for example, the reference electrode.
This is because, in addition to the electric field related to the original display between the display electrode and the reference electrode, an electric field unrelated to the original display is generated between the video signal line and the reference electrode. .

Patent application publication No. 5-505247 JP-B-63-21907 JP-A-6-160878 and the like

  For this reason, as described above, the light-shielding film provided for preventing the characteristic deterioration due to light irradiation on the thin film transistor made of a semiconductor material sufficiently covers the region between the video signal line and the reference electrode. Due to the additional requirement that the substrate must be aligned, a problem has been pointed out that a considerable degree of accuracy is required for alignment with another transparent substrate.

For this reason, the video signal line and the reference electrode are overlapped with each other via an insulating film so that a region between them is not formed, or the video signal line and the reference electrode which are adjacently arranged are not overlapped. those between the structure covered with a metal conductive film through the insulating film has come to be proposed by the applicant, respectively.

  However, in the former case, there remains a problem that the occurrence of short-circuit defects due to insulation failure of the insulating film interposed between the video signal line and the reference electrode which are arranged to overlap each other cannot be avoided.

Further, in the latter case, the occurrence of the short-circuit defect as in the former can be suppressed, but when the short-circuit defect occurs between the video signal line and the reference electrode for some reason, the metal conductive film is not used. The opaque material makes it difficult to find the short-circuit defect, and the problem remains that the repair work is difficult.

  The present invention has been made in view of such circumstances, and an object of the present invention is to increase a margin of alignment of transparent substrates disposed to face each other, and to provide a video signal line and a video signal line adjacent to the video signal line. An object of the present invention is to provide an active matrix liquid crystal display panel that can easily find and repair a short circuit defect between another electrode and a short circuit.

  The following is a brief description of an outline of typical inventions disclosed in the present application.

  Among the transparent substrates disposed to face each other with the liquid crystal layer interposed therebetween, a display electrode and a reference electrode are provided on an area surface corresponding to one or both of the liquid crystal side unit pixels. The light transmitted through the liquid crystal layer is modulated by an electric field generated in parallel with the transparent substrate between the reference electrode and the reference electrode, and the display electrode is turned on by supplying a scanning signal to a scanning signal line. A video signal is supplied from a video signal line via a switching element, and the reference electrode is supplied with a reference signal from a reference signal line, and in an active matrix liquid crystal display panel in a normally black display mode, In a region between a video signal line and another electrode disposed adjacent to the video signal line, another video signal line and another video signal line adjacent to the video signal line are interposed via an insulating film. Its conductive layer so as to partially overlap is formed on the electrode, the conductive layer is characterized in that it is formed of a transparent material.

  The active matrix type liquid crystal display panel configured as described above includes the above-described video signal line and the video signal line in an area between the video signal line and another electrode disposed adjacent to the video signal line via an insulating film. In addition, since the conductive layer is formed so that a part thereof overlaps with the adjacent other electrode, the electric field generated by the video signal line and the other electrode terminates on the conductive film side, and the liquid crystal layer side , And is not formed.

In other words, the presence of the conductive film makes it possible to make the potential of the region between the video signal line and another electrode adjacent to the video signal line equivalent.
Since the conductive film is formed of a transparent material, even when a short-circuit defect occurs between the video signal line and another electrode disposed adjacent to the video signal line, Short-circuit defects can be easily found through the conductive film, and the repair work can be simplified.
Furthermore, since the light transmission of the liquid crystal layer has a so-called normally black structure, the portion where the conductive film is formed has the function of a light shielding film.

  For this reason, the light-shielding film on the other transparent substrate, which is disposed so as to face the transparent substrate on which the video signal line is formed, can be formed to extend in a direction orthogonal to the extending direction of the video signal line. It is possible to increase the allowance when positioning the transparent substrates facing each other.

  Therefore, it is possible to increase the margin of alignment of the transparent substrates disposed to face each other, and when a short-circuit defect occurs between the video signal line and another electrode adjacent to the video signal line, the discovery and detection thereof are performed. Restoration can be facilitated.

  ADVANTAGE OF THE INVENTION According to the active matrix type liquid crystal display panel by this invention, the tolerance of the alignment of the transparent substrate arrange | positioned mutually opposing can be enlarged, and between a video signal line and another electrode adjacent to this video signal line. When a short-circuit defect occurs, it can be easily found and repaired.

  Hereinafter, embodiments of the active matrix type liquid crystal display panel according to the present invention will be described.

  First, as shown in FIG. 2, there is a liquid crystal display panel 1, and one of the transparent substrates 1 A and 1 B disposed opposite to each other via a liquid crystal layer of the liquid crystal display panel 1 is provided on a liquid crystal side surface of the transparent substrate 1 A. , A scanning signal line 2 and a reference signal line 4 extending in the x direction (row direction) and juxtaposed in the y direction (column direction) are formed.

In this case, in this figure, from above the transparent substrate 1A, a reference signal line 4, a scanning signal line 2 relatively separated from the reference signal line, a reference signal line 4 close to the scanning signal line 2, The scanning signal lines 2, which are relatively spaced apart from the reference signal line 4, are arranged sequentially.
Further, a video signal line 3 which is insulated from the scanning signal line 2 and the reference signal line 4 and extends in the y direction and is juxtaposed in the x direction is formed.

  Here, a unit region is formed in each of a rectangular region having a relatively large area surrounded by the scanning signal line 2, the reference signal line 4, and the video signal line 3, and these unit pixels are arranged in a matrix. And constitute a display surface. The detailed configuration of each of these pixel regions will be described later.

  The liquid crystal display panel 1 includes a vertical scanning circuit 5 and a video signal driving circuit 6 as external circuits, and the vertical scanning circuit 5 sequentially supplies a scanning signal (voltage) to each of the scanning signal lines 2. The video signal drive circuit 6 supplies a video signal (voltage) to the video signal line 3 in accordance with the timing.

  The vertical scanning circuit 5 and the video signal driving circuit 6 are supplied with power from the liquid crystal driving power supply circuit 7 and are configured so that image information from the CPU 8 is divided into display data and control signals by the controller 9 and input. Has become.

  In addition, the liquid crystal display panel 1 having the above-described configuration is particularly provided with a reference signal line 4, and a reference voltage signal applied to the reference signal line 4 is also supplied from the liquid crystal drive power supply circuit 7.

  FIG. 1 is a plan view showing an embodiment of the unit pixel (corresponding to a region surrounded by a dotted line in FIG. 2). FIG. 4 is a sectional view taken along the line IV-IV in FIG. 1, FIG. 5 is a sectional view taken along the line VV, and FIG. 6 is a sectional view taken along the line VI-VI.

  FIG. 1 shows a structure in which a conductive layer 100 made of, for example, ITO, which is particularly provided in this embodiment, is formed. However, this conductive layer 100 is formed in view of the structure of the lower layer described earlier. First, a description will be given based on FIG.

  In FIG. 3, a reference signal line 4 extending in the x direction and a scanning signal line 2 separated from and parallel to the reference signal line 4 are formed on the main surface of the transparent substrate 1A.

  Here, two reference electrodes 14 are integrally formed on the reference signal line 4. These two reference electrodes 14 scan in the y direction side of a pixel region formed by a pair of adjacent video signal lines 3 described later, that is, in the (−) y direction in proximity to the respective video signal lines 3. It is formed to extend to the vicinity of the signal line 2.

  On the surface of the transparent substrate 1A on which the scanning signal lines 2, the reference signal lines 4, and the reference electrodes 14 are formed, the insulating film 15 made of, for example, a silicon nitride film (see FIG. , FIG. 5 and FIG. 6). This insulating film 15 accumulates as an interlayer insulating film at an intersection with the scanning signal line 2 and the reference signal line 4 for a video signal line 3 described later, and as a gate insulating film for a region where the thin film transistor TFT is formed. The region for forming the capacitor Cstg functions as a dielectric film.

  First, on the surface of the insulating film 15, a semiconductor layer 16 is formed in a region where the thin film transistor TFT is formed. The semiconductor layer 16 is made of, for example, amorphous Si, and is formed on the scanning signal line 2 so as to overlap with a substantially central portion of the adjacent video signal line 3. Thus, a part of the scanning signal line 2 also serves as a gate electrode of the thin film transistor TFT.

Then, on the surface of the insulating film 15 thus formed, as shown in FIG. 3, the video signal lines 3 extending in the y direction and juxtaposed in the x direction are formed.
The video signal line 3 is integrally provided with a drain electrode 3A formed to extend to a part of the surface of the semiconductor layer 16 of the thin film transistor TFT.

  Further, a display electrode 18 is formed on the surface of the insulating film 15 in the pixel region. The display electrode 18 is formed so as to run between the reference electrodes 14. That is, the display electrode 18 has one end serving also as the source electrode 18A of the thin film transistor TFT, extends in the (+) y direction as it is, reaches the reference signal line 4, and further extends on the reference signal line 4 in the traveling direction. It has a T-shape extending slightly to both sides.

  In this case, a portion of the display electrode 18 that overlaps with the reference signal line 4 forms a storage capacitor Cstg including the insulating film 15 as a dielectric film between the display electrode 18 and the reference signal line 4. The storage capacitor Cstg has an effect of storing video information on the display electrode 18 for a long time when the thin film transistor TFT is turned off, for example.

  The surface of the semiconductor layer 16 corresponding to the interface between the drain electrode 3A and the source electrode 18A of the thin-film transistor TFT is doped with phosphorus (P) to form a high-concentration layer. I am trying to make a contact. In this case, the high-concentration layer is formed on the entire surface of the semiconductor layer 16, and after forming each of the electrodes, the high-concentration layer other than the electrode formation region is etched using the electrodes as a mask. The above configuration can be adopted.

The protective film 19 made of, for example, a silicon nitride film is formed on the upper surface of the insulating film 15 on which the thin film transistor TFT, the video signal line 3, the display electrode 18, and the storage capacitor Cstg are formed (FIGS. 4, 5, and 6). On the upper surface of the protective film 19, as described above, the conductive film 100 made of, for example, ITO, particularly provided in the present embodiment, is formed.

That is, as shown in FIG. 1, the video signal line 3 and the video signal line 3 are disposed in a region between the video signal line 3 and the reference electrode 14 disposed adjacent to the video signal line 3 via the protective film 19. A conductive film 100 part of which overlaps with another electrode adjacent to the line is formed of ITO. Then, the conductive film 100 is extended span the other pixel region along the video signal line 3, the side portion on the reference electrode 14 (via the protective film 19) is superimposed.

Thus constituted conductive film 100, I can coupled with adopting a so-called normally black mode, as described later in this liquid crystal display panel 1, so that achieve the great effect, after this effect It will be described in detail.

And, on the upper surface of the protective film 19 such conductive film 100 is formed, the alignment layer 20 also covers the conductive film 100 is formed (see FIG. 4, 5 and 6), thereby the liquid crystal display panel 1 Of the lower substrate. Note that a polarizing plate 21 is disposed on a surface of the lower substrate opposite to the liquid crystal layer side.

Further, a light-shielding film 22 is formed on a portion on the liquid crystal side of the transparent substrate 1B serving as the upper substrate.
The light-shielding film 22 is usually formed in a region corresponding to the periphery of each pixel region. In this embodiment, particularly, the light-shielding film 22 is formed in a region corresponding to a dashed line in FIG. That is, the light-shielding film 22 is not intentionally formed in the region where the conductive film 100 is formed. The reason for this is that the conductive film 100 also has the function of the light-shielding film 22 by employing the normally black method, as will be described in detail later.

  For this reason, the light-shielding film 22 formed on the transparent substrate 1B side has a function of preventing the thin film transistor TFT from being directly irradiated with light and a function of improving display contrast together with the conductive film 100. It has become something.

  Further, as shown in FIG. 4, a color filter 23 is formed on the surface of the transparent substrate 1B on which the light-shielding film 22 (not shown) is formed on the liquid crystal layer side, and the color filter 23 is adjacent to the x direction. Each pixel region has a different color from that of the pixel region, and has a boundary on the video signal line 3. A flat film 24 made of a resin film or the like is formed on the surface on which the color filters 23 are formed, and an alignment film 25 is formed on the surface of the flat film 24. Note that a polarizing plate 26 is disposed on the surface of the upper substrate opposite to the liquid crystal layer side.

  Here, the relationship between the alignment film 20 formed on the transparent substrate 1A and the polarizing plate 21 and the relationship between the alignment film 25 formed on the transparent substrate 1B and the polarizing plate 26 will be described with reference to FIG.

  The angle of the rubbing direction 208 of each of the alignment films 20 and 25 with respect to the direction 207 of the electric field applied between the display electrode 18 and the reference electrode 14 is φLC. The angle of one polarizing plate 21 in the polarization transmission axis direction 209 is φP. The polarization transmission axis of the other polarizing plate 26 is orthogonal to φP. In addition, φLC = φP. As the liquid crystal layer LC, 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. Used.

  The configuration of the alignment films 20 and 25 and the polarizers 21 and 26 having such a relationship is what is called a normally black mode, and generates an electric field E parallel to the transparent substrate 1A in the liquid crystal layer LC. This allows light to pass through the liquid crystal layer LC.

In the liquid crystal display panel shown as in this embodiment, the video signal line and the reference electrode adjacent to the video signal line are provided in a region between the video signal line 3 and the reference electrode 14 via a protective film 19. as part overlap, by a conductive film 100 is formed, the electric field generated by the video signal line 3 and the reference electrode 14, would be terminated to the conductive layer 100 side, it extends to the liquid crystal layer side It will not be formed.

  In other words, the presence of the conductive film 100 makes it possible to make the potentials of the video signal line 3 and the reference electrode 14 equivalent for the liquid crystal layer.

  Since the conductive film 100 is formed of a transparent material made of ITO, even when a short-circuit defect occurs between the video signal line 3 and the reference electrode 14, the conductive film 100 is formed. , The short-circuit defect can be easily found, and the repair work can be simplified.

  Further, since the light transmission of the liquid crystal layer is shielded when an electric field is not formed in the liquid crystal layer, a so-called normally black structure is provided. Will have the function of

  For this reason, the light-shielding film 22 on the side of the other transparent substrate 1B, which is disposed to face the transparent substrate 1A on which the video signal lines 3 are formed, extends in a direction orthogonal to the direction in which the video signal lines 3 extend. , And the tolerance for alignment of the transparent substrates 1B opposed to each other can be increased.

  Therefore, the alignment margin of the transparent substrates 1A and 1B opposed to each other can be increased, and when a short-circuit defect occurs between the video signal line 3 and the reference electrode 14, it is easy to find and repair it. Will be able to

In the foregoing embodiment, the side portions of the conductive film 100 formed along the video signal line on the reference electrode 14 (via the protective film 19) is obtained by forming superimposed. However, this configuration is intended to improve the aperture ratio, and is not necessarily limited to this.

Further, in the embodiment described above, it is obtained so as to form a conductive film 100 between the video signal line 3 and the reference electrode 14. However, for example, such as the display electrode 18 is in the intended structure as disposed adjacent to the video signal line 3, it is needless to say that may be provided with a conductive film 100 therebetween. In short, the present invention can be applied between the video signal line 3 and another electrode arranged adjacent to the video signal line.

Furthermore, in the embodiment described above, but in which ITO was used as the material of the conductive film 100 is not limited thereto, for _example, may be SnO 2, _In 2 _{O 3,} etc., also, Needless to say, it may be formed by laminating two or more of these.

In the above-described liquid crystal display panel, the terminals of the video signal line 3, the scanning signal line 2, and the reference signal line 4 are formed of a transparent material such as ITO to prevent, for example, electric contact. is there. In this case, by forming the terminals at the same time when the conductive film 100 is formed, the number of manufacturing steps can be reduced.

As shown in FIG. 8, the conductive film 100 is divided for each pixel region, that is adapted to be formed independently for each pixel region.
In other words, unless the conductive film 100, the video signal line 3, and the reference electrode 14 are simultaneously short-circuited in each pixel region, in other words, only the conductive film 100 and the video signal line 3 are short-circuited or the conductive film 100 Short-circuiting only with the reference electrode 14 means that there is no problem at all, and has an effect that the yield can be improved as compared with the first embodiment.

As shown in FIG. 9, the conductive film 100, together are formed independently for each pixel region, so that the lattice-like pattern can be formed when viewed in plan and the conductive film 100 and the light-shielding film 22 In addition, the length of the conductive film 100 along the video signal line 3 is minimized.
By doing so, the area of the conductive film 100 can be reduced, it is possible to reduce the probability of a simultaneous short circuit between the conductive film 100 and the video signal line 3 and the reference electrode 14. Therefore, the yield can be improved.

  In each of the above-described embodiments, the conductive film 100 is provided on the video signal line 3 and another electrode adjacent to the video signal line 3 in any of the above embodiments. However, the same effect can be obtained even if it is provided on the lower layer side. Most of the electric field generated from the video signal line 3 and the other electrode adjacent to the video signal line 3 terminates on the conductive film 100 side, and only a small remaining portion on the liquid crystal layer side. This is because it does not occur.

FIG. 1 is a plan view of a main part showing an embodiment of an active matrix type liquid crystal display panel according to the present invention. 1 is a schematic configuration diagram showing one embodiment of a liquid crystal display device to which an active matrix type liquid crystal display panel according to the present invention is applied. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of a principal part showing an embodiment of an active matrix type liquid crystal display panel according to the present invention. FIG. 4 is a sectional view taken along line IV-IV in FIG. 1. FIG. 5 is a sectional view taken along line VV of FIG. 1. It is sectional drawing in the VI-VI line of FIG. FIG. 3 is an explanatory diagram showing that the active matrix type liquid crystal display panel according to the present invention employs a normally black system. FIG. 11 is a plan view of a principal part showing another embodiment of the active matrix type liquid crystal display panel according to the present invention. FIG. 11 is a plan view of a principal part showing another embodiment of the active matrix type liquid crystal display panel according to the present invention.

Explanation of reference numerals

2 ... scanning signal lines, 3 ... video signal lines, 4 ... reference signal line, 14 ... reference electrode, 18 ... display electrode, 22 ... light shielding film, 100 ... conductive film.

Claims (4)

In a horizontal electric field type liquid crystal display panel having a scanning signal line, a video signal line, a display electrode, and a reference electrode on one of the transparent substrates disposed opposite to each other with a liquid crystal layer interposed therebetween,
Formed of a transparent material, the liquid crystal layer has a conductive film that makes the potential of the video signal line and the reference electrode equivalent, and the conductive film has a function of a light-shielding film by being normally black,
A terminal of the video signal line is formed of the transparent material, and is formed in the same layer as the conductive film . The liquid crystal display panel of claim 1, wherein the conductive film _ITO, a SnO 2, _In 2 _{O 3} or their lamination. The terminal of the video signal lines and the scanning signal lines are formed of a transparent material, the liquid crystal display panel according to claim 1, characterized in that it is formed in the conductive film and the layer having the function of the light shielding film. The liquid crystal display device characterized by using the liquid crystal display panel according to any one of claims 1 to 3.

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