JP2667149B2 - LCD panel - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display panel (hereinafter abbreviated as an LCD panel), and particularly to an active matrix type large LCD display panel using a TFT or the like. 2. Description of the Related Art As shown in FIG. 4 and FIG. 5, an active matrix type LCD panel using a TFT or the like has a transparent pixel electrode 2 on a main surface and a control element 3 such as a TFT for controlling the pixel electrode 2. ,
Further, a transparent main substrate 1 made of glass or the like having a scanning signal line pattern 4 and an image signal line pattern 5 for selectively driving the control element group, and a transparent conductive film, so-called, on the entire main surface of the transparent substrate such as glass. A transparent substrate 7 for a common electrode on which an ITO film 6 is adhered is closely arranged at an interval of about 10 μm.
Is obtained by injecting and sealing a liquid crystal 9 into the gap portion 8 of FIG. In the drawing, reference numeral 10 denotes a color filter in the case of a color display panel, and reference numerals 11 and 12 denote external lead electrode terminal portions of the scanning signal line pattern 4 and the image signal line pattern 5, respectively. Problems to be Solved by the Invention A transparent common electrode used for an LCD panel is generally formed on a transparent substrate 7 by a transparent conductive thin film as described above.
Although an O film 6 is used, it is preferable that the ITO film 6 is formed thin in consideration of light transmittance.
It is formed with a film thickness of about
It is about 100Ω / □. In addition, a connection electrode portion of the ITO film 6 which is an opposing common electrode with an external circuit is often provided at a corner portion such as a corner portion of the panel due to the configuration of the LCD panel. When the size of the LCD panel is small, even if the opposing common electrode is configured by the above method, the spread resistance in the ITO film 6 does not hinder the practical use, but the size of the LCD panel increases. As a result, the spreading resistance in the ITO film 6 becomes a factor that adversely affects image quality. That is,
The film resistance is different between the vicinity of the external circuit connection electrode portion and the portion farthest from the external circuit connection electrode portion. When the ITO film 6 is used as a counter common electrode, a difference occurs in the electric potential in the same film surface, and each unit in the LCD panel is different. The display characteristics of the pixel portion are uneven, which hinders the provision of an LCD panel having a uniform pixel image. Especially,
Using a plurality of large LCD panels 13 as shown in FIG.
An ultra-large panel that electrically connects the panels electrically and physically, and connects the electrode terminals 11 and 12 on the outer periphery and the external connection terminal 14 of the opposing common electrode to an external control drive circuit after bonding. In the LCD display system, since the external connection portion of the opposing common electrode is limited due to its configuration, the above-described film resistance of the ITO film 6 becomes a larger problem. As a means for solving this problem, it is conceivable to lower the sheet resistance of the ITO film 6. However, in order to reduce the sheet resistance, it is necessary to increase the thickness of the ITO film 6, or to take a measure such as changing the composition of the ITO film 6, that is, the film quality. In order to reduce the light transmittance, one function as a transparent conductive film is impaired. Therefore, an object of the present invention is to reduce the sheet resistance of the ITO film 6 without lowering the light transmittance. Means for Solving the Problems And in order to achieve this object, the present invention provides a transparent main substrate, a transparent substrate for a common electrode, which is disposed facing the transparent main substrate at a predetermined interval, and a transparent main substrate And a liquid crystal sealed between the transparent substrates for the common electrode, and a plurality of transparent pixel electrodes and a control element for controlling these pixel electrodes are provided on the liquid crystal side surface of the transparent main substrate, On the liquid crystal side surface of the common electrode transparent substrate, a transparent conductive film was provided on the entire surface, and the film thickness of the portion of the transparent conductive film facing the control element was made larger than the film thickness of the portion facing the pixel electrode. Things. With the above structure, a thick portion is provided in the transparent conductive film, so that the overall sheet resistance can be reduced. As a result, the display characteristics of the panel do not become uneven, and the thick portion has a large thickness. Is a portion facing the control element for controlling the pixel electrode and is originally a non-light-transmitting portion, so that the light transmittance does not decrease. Embodiment FIG. 1 is an enlarged partial cross-sectional view showing a cross-sectional structure of an LCD panel according to an embodiment of the present invention when the LCD panel is completed. FIG. 2A
1 to D are enlarged cross-sectional views illustrating a method for manufacturing the opposed common transparent electrode of the present invention. Each drawing is arbitrarily enlarged for convenience of explanation. The same parts as those in the conventional example are denoted by the same reference numerals. The details will be described below with reference to the drawings. First, as shown in FIG. 2A, the main surface of the transparent substrate for common electrode 7 is coated with an ITO film 6 as a transparent counter electrode on the entire surface for several thousand times.
Å Deposit with a film thickness of at least. Next, as shown in FIG. 2B, a photoresist pattern 15 is formed on the ITO film 6 by a method similar to a normal photolithography process. At this time, the pattern width Wi of the photoresist pattern 15 is as shown in FIG. 1 (FIG. 5).
Equivalent to the width Wp of the non-translucent part formed by the control wiring pattern of the X column and the Y row including the control element 3 such as the TFT formed on the main substrate 1 shown in FIG. 2 or the width Wb of the black stripe 16 of the color filter 10. Or, set Wp, Wb> Wi. Also, the pattern pitch Pi is the same as the X row and the Y row on the main substrate 1.
A grid pattern having the same shape as the planar pattern shape on the main substrate 1 in FIG. 5 is formed so as to have the same pitch P ₁ , P ₂ (FIG. 5) of the control wiring pattern in the row. Formed. Next, as shown in FIG. 2C, the photoresist film 15 is used as a mask to selectively reduce the film thickness of the ITO film 6 in the light-transmitting region, and the ITO film in the same region is formed into a thin film ITO film having a thickness of 1000 Å or less. After forming the film 6A, if the photoresist pattern 15 is removed, the ITO film 6 becomes a thin film ITO film 6A that emphasizes light transmission, and a thick film ITO film that emphasizes area and conductivity, as shown in FIG. 2D.
It can be an ITO film electrode composed of two layers in the film 6 region. Incidentally, the lattice-shaped low-resistance ITO film (thin film layer) 6A is arranged in a vertical or horizontal stripe depending on the shape of the LCD panel in addition to being arranged in a lattice as in the above example. Is also good. The transparent opposing common electrode (ITO
A transparent substrate 7 for a common electrode having films 6 and 6A is placed close to a transparent main substrate 1 having a functional element formed on its main surface with a gap of about 10 μm via a spacer 17 as shown in FIG. The liquid crystal 9 is injected into the gap portion 8 and sealed by sealing.
A panel is obtained. As is clear from FIG. 1, in the LCD panel using the transparent substrate 7 for a common electrode according to the manufacturing method of the present invention, the transparent counter common electrode in the pixel region 19 for controlling the transmitted light 18 from a light source (not shown). Since the ITO film 6A is thin, the loss due to absorption of transmitted light at the same portion can be reduced, and the ITO film 6 at the portion facing the non-transmissive region 20 formed by the control element 3 and the like has a low thickness. Since the transparent common electrode film is formed as a resistance layer, the surface resistance of the transparent common electrode film can be reduced. Furthermore, as an embodiment of a more simplified configuration, an ITO film of 1000 ° or less is formed over the entire main surface of the common electrode transparent substrate 7, and the outer peripheral area of this ITO film, that is, the outer side of the common electrode transparent substrate 7 is formed. By forming an ITO film electrode having a two-layer structure in which a highly conductive ITO film layer having a thickness of several thousand mm or more is formed in the light non-transmissive region in the peripheral portion, compared to the above-described Examples 1 and 2, If this is the case, the sheet resistance increases, but the transparent electrode for the common electrode has a structure having a highly conductive electrode on the outer periphery. Therefore, the film sheet resistance is reduced as compared with the conventional example, and the image quality can be improved. . 3A to 3E are schematic cross-sectional views showing a method of manufacturing a common electrode (ITO film 6) according to another embodiment of the present invention. First, an ITO film 6 is deposited on the entire main surface of the common electrode transparent substrate 7 to a thickness of several thousand degrees or more (FIG. 3A). Next, a photoresist pattern 15 having a predetermined pattern shape is formed on the ITO film 6 as in the previous embodiment (FIG. 3B).
After etching the ITO film 6 using the photoresist pattern 15 as a mask (FIG. 3C), the photoresist pattern 15
Is removed to form a thick ITO film 6 pattern of a predetermined shape on the main surface (FIG. 3D). Thereafter, the ITO film 6 is again applied to the main surface of the common electrode transparent substrate 7.
If A is applied over the entire surface with a thickness of several hundreds to 1000 degrees, two types of ITO films 6, 6A having different thicknesses are formed on the main surface of the common electrode transparent substrate 7 as shown in FIG. 3E. It is formed. Then, if an LED panel is manufactured using the transparent substrate for common electrode 7 in the same manner as in the first embodiment, an LCD panel having the same effects as in the previous embodiment can be obtained. Effect of the Invention As described above, the present invention provides a transparent main substrate, a transparent substrate for a common electrode which is disposed to face the transparent main substrate at a predetermined interval, and sealing between the transparent main substrate and the transparent substrate for the common electrode. And a liquid crystal side of the transparent main substrate,
A plurality of transparent pixel electrodes and a control element for controlling these pixel electrodes are provided.A transparent conductive film is provided on the entire surface of the common electrode transparent substrate on the liquid crystal side. The thickness of the portion facing the control element is larger than the thickness of the portion facing the pixel electrode. With the above structure, the transparent conductive film is provided with a thick portion, so that the overall sheet resistance can be reduced. As a result, the display characteristics of the panel do not become uneven, and the thick portion is formed. Is a portion facing the control element for controlling the pixel electrode and is originally a non-light-transmitting portion, so that the light transmittance does not decrease.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged cross-sectional view of an LCD panel according to an embodiment of the present invention when a LCD panel is completed, and FIGS. 2A to 2D are enlarged cross-sectional views showing a method of manufacturing a transparent substrate for a counter common electrode according to the present invention. FIGS. 3A to 3E are enlarged sectional views showing a method of manufacturing a transparent substrate for a counter common electrode according to another embodiment of the present invention, FIG. 4 is an enlarged sectional view of a conventional LCD panel, and FIG. FIG. 6 is a plan view showing an example of the planar shape of the main substrate of the LCD panel, and FIG. 6 is a perspective view showing the concept of a large display panel having a configuration in which a plurality of LCD panels are bonded. 1 ... Transparent main substrate, 2 ... Pixel electrode, 3 ... Control element such as TFT, 4 ... Scanning signal pattern, 5 ... Image signal pattern, 6,6A ... Transparent conductive film (ITO film), 7 ... Transparent substrate for common electrode, 8 ... Gap, 9 ... Liquid crystal, 10 ... Color filter, 11 ... Scan signal pattern lead-out electrode terminal portion, 12 ... Image signal pattern lead-out electrode terminal portion, 13 ... …
Multi-panel LCD, 14 ... External connection terminal of counter common electrode, 15 ... Photoresist pattern unit pixel area, 16 ...
... black stripe, 17 ... spacer, 18 ... transmitted light, 19 ... pixel area, 20 ... non-transmission area.

Claims (1)

(57) [Claims] A transparent main substrate, a transparent substrate for a common electrode disposed opposite to the transparent main substrate at a predetermined interval, and a liquid crystal sealed between the transparent main substrate and the transparent substrate for the common electrode; On the surface on the liquid crystal side, a plurality of transparent pixel electrodes and a control element for controlling these pixel electrodes are provided,
A transparent conductive film is provided on the entire surface of the common electrode transparent substrate on the liquid crystal side, and a film thickness of a portion of the transparent conductive film facing the control element is larger than a film thickness of a portion facing the pixel electrode. Liquid crystal display panel.