JP2600200B2 - Thin film active element substrate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thin-film active element substrate in which a large number of thin-film active elements are arranged near intersections of matrix electrodes.

(Prior art) Recently, flat displays have been actively developed due to demands for powders of OA equipment and portable televisions. Among them, in an information display device in which electrodes are arranged in a matrix in order to correspond to a large-capacity graphic display, an active matrix system in which an active element is arranged near the electrode intersection and driven is studied. FIG. 2 shows an equivalent circuit diagram of a liquid crystal panel display using a thin film transistor (hereinafter referred to as TFT) as a thin film active element in a part of FIG. Reference numeral 21 denotes a liquid crystal layer, and reference numeral 22 denotes a switching TFT for driving the liquid crystal layer. Reference numeral 23 denotes a data line for applying a voltage required to drive the liquid crystal, and reference numeral 24 denotes a selection signal line for controlling the gate of the TFT 22. V _DS is the drain of the ON state of the TFT 22 - a source voltage, V _LC is a voltage across the liquid crystal layer 21. Conventionally, the active matrix method, in which an active element is incorporated near the electrode intersection, and driven, has a wider response, gradation, contrast ratio, and viewing angle than the simple matrix method, which is a driving method in which no active element is incorporated. It is much better in such as.

(Problems to be Solved by the Invention) On the other hand, as shown in FIG. 2, the TFT 22 is connected in series with the liquid crystal layer 21, and when the impedance between the drain and the source in the ON state of the TFT 22 is high, the TFT 22 is applied to the liquid crystal layer. effective voltage V _LC across the liquid crystal layer due to causes such as the driving voltage of the data you wish line causes a voltage drop at the portion of the TFT22 ends up eroded only V _DS. As a result, even if the TFT 22 is turned on, a voltage sufficient to drive the liquid crystal is not applied, and the quality as an information display device such as responsiveness, gradation, and contrast may be deteriorated. Can not know. Also, changing the drive voltage of the data line is not possible with a drive IC even if the voltage applied to the liquid crystal layer 21 is to be increased.
It is extremely difficult because of the standards.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and has a structure in which pixel electrodes are arranged in a matrix on an insulating substrate, and a thin film active element is provided near an intersection of the pixel electrodes. In the thin film active element substrate provided with, a pixel electrode for inspection without a thin film active element is provided on the insulating substrate, and an electrode line is arranged so as to be connected to the pixel electrode for inspection. A thin film active element substrate is provided. In addition, the inspection pixel electrode is provided in a region where the product pixel is in a viewable range of the display screen of the thin film active element substrate but is not used as a product, and the thin film active element substrate and the liquid crystal layer A thin film active element substrate provided with a thin film active element substrate, wherein a voltage can be applied between an electrode on which no thin film active element is provided and an inspection pixel electrode on an insulating substrate opposed to the thin film active element. I do.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 shows a sectional view of the basic structure of the present invention. In FIG. 1, 10
Denotes an insulating substrate, 11 denotes a pixel electrode, 12 denotes an electrode line of the present invention, and 13 denotes a liquid crystal layer. The insulating substrate 10 is one of two plate-like bodies on which the pixel electrode 11 and the like are formed and the liquid crystal layer 13 is interposed therebetween, and a glass plate, a synthetic resin plate, or the like can be used. Pixel electrode 11
Is for applying a voltage to the liquid crystal layer 13, and ITO or another metal or metal compound is used. The material of such a pixel electrode may be different from the material of another pixel electrode having a TFT due to photolithography. The electrode wire 12 is a point of the present invention, and the liquid crystal layer is connected through the electrode wire 12.
The function of directly applying the voltage applied to the pixel electrode 11 to the pixel electrode 11 is achieved. The electrode wire 12 may have a single-layer structure, but preferably has a two-layer structure to prevent defects such as disconnection.

The material of the electrode wire 12 is Cu, Ag, Au, A
Considering the price, etc., metals such as l can be used, and Al is desirable.Cr, Mo, Ti, W, etc. can be generally used as those having a high melting point. desirable. When the electrode wire 12 has a two-layer structure as described above, it is preferable that the material of the first layer has a higher melting point than that of the second layer so that the first layer is hardly corroded. What is necessary is just to select. In the case of a two-layer structure, the following method can be used to reduce the number of manufacturing steps. During the same photolithography step of patterning the pixel electrode 11 on the insulating substrate, the first layer of the electrode line 12 is simultaneously patterned (in this case, naturally, the material of the first layer of the electrode line 12 is the same as that of the pixel electrode 11). ), And the second layer is patterned thereon by a photolithography process different from the above-described photolithography process. By doing so, the number of manufacturing steps can be reduced, which can contribute to a reduction in time and cost. In this case, the material of the first layer desirably has a higher melting point than that of the second layer so as to be less likely to be eroded during the formation of the second layer, and may be selected from the above-mentioned metals so as to be like this.

As described above, the structure of the present invention is in contact with the inspection pixel electrode 11 having no TFT driven by the electrode line 12, and a voltage can be directly applied to the liquid crystal layer 13 via the electrode 12.
The inspection pixel electrode 11 having such a structure is also connected to the electrode line 12.
Usually, one or more TFTs having thousands to hundreds of thousands of TFTs may be formed as needed, and a region to be formed is formed in a region other than a region used for manufacturing. It is normal to form the electrode 11 and the electrode wire 12,
In this case: 1) After completion as the final product, it is hidden behind the frame of the display screen and cannot be seen.

2) Although it is within the range that can be visually recognized as the final product on the display screen, the location is not actually used as the product. (After the product is completed, it is only necessary to take measures so that the part does not turn on.) There is also a possibility that the area to be formed is turned on and off by an element other than the thin film active element substrate, a switch, or the like. And may be a visible location (for example, a decimal point of a number).

The electrode line 12 may be connected to the data line 23 or may be pulled out to the end of the insulating substrate 10 (preferably the end closest to the pixel electrode 11 for inspection), and an electrode (hereinafter referred to as an optical inspection) there. May be formed, connected to such an electrode, and a voltage is applied to the optical inspection terminal to light it.

FIG. 2 shows an equivalent circuit of a part of a TFT substrate partially including the present invention.

In FIG. 2, reference numeral 25 denotes an optical inspection terminal of the insulating substrate 10 connected to the above-mentioned electrode line 12, and reference numeral 26 denotes a liquid crystal layer connected to the electrode 12.

[Operation] In the present invention, when a voltage is applied to the terminal for optical inspection, a voltage is directly applied to the pixel electrode for inspection, and when a voltage is applied to the pixel electrode via the TFT, there is no voltage drop that is lost by the TFT, so driving is performed. The optical characteristics of the liquid crystal and the like to be obtained can be known accurately.

[Example] Optical inspection terminal according to the present invention and an inverted stagger structure TFT
Since the TFT substrate having the above structure was prepared, the fabrication thereof will be described below.

As shown in the sectional view of FIG. 3, a transparent conductive film such as ITO was laminated on the insulating substrate 10 as the pixel electrode 51 by about 500 mm.
Subsequently, the gate electrode 52 was laminated using Cr by about 500 Å and patterned. Si from above the pixel electrode 51 and the gate electrode 52
ON is about 2000 mm as the transparent insulating film 53, and the semiconductor layer 55
A-Si was laminated at about 1000 ° and patterned. Further, a source electrode 56 and a drain electrode 57 were each laminated by 3000 Å using Al and patterned. Both such electrodes a
-N ⁺ a-Si layer at the contact portion with -Si.

Next, the optical inspection terminal of the present invention shown in FIG.
A pixel electrode 11 for inspection was formed on an insulating substrate 10 having a TFT by using ITO (about 500 °). The electrode wire 12 was patterned thereon using Cr (about 500 °).

A liquid crystal TFT substrate was prepared from the substrate prepared as described above, and a voltage was directly applied to the pixel electrode 11 for inspection by the electrode wire 12. As a result, even in the single liquid crystal TFT substrate, the liquid crystal to which the voltage was directly applied through the electrode line 12 was somewhat superior in the wide viewing angle and the like, as compared with the liquid crystal to which the voltage was applied through the TFT. .

[Effects of the Invention] The present invention applies a voltage to an optical inspection terminal and directly applies the voltage to an inspection pixel electrode, so that it is possible to directly know the optical characteristics of a display element such as a liquid crystal driven by the pixel electrode. Thus, by knowing the characteristic tendency of each TFT substrate for each lock such as TFT and liquid crystal, it is possible to adjust the manufacturing process and use it to manufacture a uniform product.

[Brief description of the drawings]

FIG. 1: Cross-sectional view of the basic structure of the present invention FIG. 2: Partial equivalent circuit diagram of a TFT substrate partially including the present invention FIG. 3: Cross-sectional view of an inverted staggered TFT 10: Insulating substrate 11 : Pixel electrode 12: Electrode line 21, 26: Liquid crystal 22: TFT 23: Data line 24: Select signal line 25: Optical inspection terminal

Claims (3)

(57) [Claims] An image electrode for inspection without a thin-film active element provided on a thin-film active element substrate having pixel electrodes arranged in a matrix on an insulating substrate and having a thin-film active element provided near an intersection of the pixel electrodes. Is provided on the insulating substrate, and an electrode wire is arranged so as to be connected to the image electrode for inspection. 2. The thin-film active element substrate according to claim 1, wherein the inspection pixel electrode is located in an area where the product is not used, although the area is within a viewable range of the display screen of the thin-film active element substrate. 2. A voltage can be applied between an electrode on which no thin-film active element is provided on an insulating substrate facing the liquid crystal layer and a pixel electrode for inspection. Thin film active element substrate. 3. The thin film according to claim 1, wherein the electrode wire extends to an end of the insulating substrate and is connected to an optical inspection terminal disposed at the end. Active element substrate.