JPH07120694B2 - Liquid crystal display device inspection device and inspection method thereof - Google Patents

Description

The present invention relates to a liquid crystal display device and a method for inspecting the same, and more particularly to a liquid crystal display panel in which a large number of pixel electrodes are arranged in an XY matrix. The present invention relates to an apparatus and a method for inspecting the characteristics of each of the switching elements in a liquid crystal display device for displaying a dot matrix type image in which switching elements are provided on element electrodes.

<Prior Art> Conventionally, a liquid crystal display panel has been put into practical use as a display device using the electro-optical effect of liquid crystal for a television image or a character image element. This liquid crystal display panel is XY
A large number of picture element electrodes arranged in a dot matrix and a liquid crystal layer that modulates light according to a voltage applied to the picture element electrodes are provided. In some cases, color display is performed, so that the picture element electrodes are arranged corresponding to the picture elements. A coloring means is added. Particularly, in the panel to which the coloring means is added, by applying a video signal corresponding to the color corresponding to each pixel electrode,
With the same principle as a CRT (CRT), it is possible to display an arbitrary dot matrix type image that is mixed with additive colors and contains intermediate colors. In recent years, with the improvement in quality of such liquid crystal display panels, a method of adding a switching element to each of the picture element electrodes and applying a video signal to the picture element electrode via the switching element is being used. The process of forming such a switching element is complicated, and therefore problems such as defective pixels, disconnection or short circuit of scanning lines and signal lines, and defective switching elements become problems. For this reason, inspection and analysis of this kind of defective state are particularly important for quality control and quality improvement of the final product.

Conventionally, a method of inspecting the characteristics of the switching element by contacting a pixel electrode with a probe card or the like has been used as a method for inspecting the defective pixel, but it is very difficult to inspect a large number of pixels. Since it takes a long time, it was an inefficient method as a process control means.

<Structure and Operation of the Invention> In order to solve the above-mentioned problems, the present invention provides an inspection panel including a detection electrode matrix having a matrix structure similar to the pixel matrix of a liquid crystal display device, An object of the present invention is to provide an inspection apparatus capable of performing a detailed inspection of a larger number of picture elements at a higher speed than in the past by detecting the characteristic of each corresponding picture element using a matrix.

Specifically, an inspection panel in which detection electrodes are arranged in a matrix having a pitch similar to the pixels on the matrix is provided, and the detection electrode matrix of this inspection panel is a pixel matrix substrate to which switching elements of a liquid crystal display device are added. The scanning electrodes and the signal electrodes are provided so as to be opposed to each other so as to be coincident with each other, and a switching element is added to each of the detection electrodes, and the switching elements are operated by applying a voltage to the scanning electrodes. The switching element of the liquid crystal display substrate, which is arranged in contact with and in contact with the detection electrode matrix, is operated, the signal current from each pixel is input to the corresponding detection electrode, and the signal from this detection electrode is switched. The operating state of each picture element is inspected by transmitting it to the signal electrode of the inspection panel via It is obtained by way.

<Examples> Hereinafter, the present invention will be described in detail with reference to Examples shown in the drawings.

FIG. 1 shows a control mechanism of an inspection apparatus showing one embodiment of the present invention, and FIG. 2 is an enlarged view of a main part of an inspection panel 1. The inspection panel 1 is a picture element 3 of a matrix structure arranged on a substrate 2 of the XY matrix type liquid crystal display device shown in FIG.
The detection electrodes 4 are arranged in a matrix structure having a pitch similar to.

A switching element 5 formed of an amorphous silicon thin film transistor (TFT) is connected to each of the detection electrodes 4, and a scanning electrode 6 and a signal electrode 7 are provided with each switching element 5 as an intersection.

In order to manufacture the inspection panel 1 having the above structure, an X
A manufacturing process of a Y matrix type liquid crystal display device is used. That is, in the active matrix type XY matrix type liquid crystal display device by TFT, the TFT is
It has a cross-sectional structure shown in the figure, and a gate insulating film 22, a semiconductor film 23, a source electrode 24, and a drain electrode 25 are sequentially patterned and laminated on a transparent insulating substrate 20 such as glass, quartz glass, or ceramic. It is configured. As the method for forming the above-mentioned thin film, there are vacuum deposition method, sputtering method, CVD
Method, plasma CVD method, low pressure CVD method, etc., and patterned by shadow mask and photolithography techniques. This TFT is used as a switching element of the inspection panel 1 of the present invention, the gate electrodes 21 belonging to the TFTs in the same row are connected to the common inspection electrode 6, and the source electrodes 24 belonging to the TFTs in the same column are used as the common signal electrode. 7 and the drain electrode 25 is connected to the detection electrode 4. This drain electrode 25 is connected to a pixel electrode in a liquid crystal display device.

The manufacturing process of the inspection panel 1 of the present invention is not limited to the above process, but if a part of it is changed by using the manufacturing process of the liquid crystal display device of the object to be inspected, it is extremely inexpensive and easy to manufacture. Is possible.

Scan electrodes 6 and signal electrodes 7 provided on the inspection panel 1
As shown in FIG. 1, the scan electrode drive circuit 1
0, connected to the signal electrode drive circuit 11, these drive circuit 1
The control circuit 12 drives 0 and 11. The signal electrode drive circuit 11 is a signal detection circuit including an AD converter.
It is connected to a storage device 14 via 13, and this storage device 14 is connected to a computer 15.

In the above control mechanism, the scan electrode drive circuit 10 is used at the time of inspection.
A voltage is applied to the scanning electrodes 6 by the switching elements 5
Works. A detection signal obtained from the detection electrode 4 is transmitted to the signal electrode 7 via the switching element 5, and the detection signal is stored in the storage device 14 from the signal electrode 7 through the signal detection circuit 13. Further, by inputting a detection signal from the storage device 14 to the computer 15, the characteristics of the switching element of the liquid crystal display device can be accurately detected. That is, it is considered that the switching elements 5 have characteristic variations, and it is possible to prevent the characteristics of factors other than the conventional purpose from affecting the evaluation of the characteristics of the originally intended liquid crystal display device. In order to accurately evaluate the characteristics of the device, a signal voltage is applied to the liquid crystal display device with a certain reference sample (for example, a sample in which the switching element of the liquid crystal display device is replaced with a resistance element), and each pixel is applied. The current flowing into the device is measured, and the measured current value is standardized by the ratio to the reference measured value to evaluate the characteristics of the switching element of the liquid crystal display device. By processing such measurement data with the computer 15,
It is possible to obtain a useful evaluation regarding the display characteristics of the liquid crystal display device such as the disconnection defect, the pixel defect, and the display unevenness.

Next, the inspection method will be described. As shown in FIG. 3, the inspection panel 1 is arranged in a liquid crystal display so that the matrix of the detection electrodes 4 of the inspection panel 1 and the matrix of the pixel electrodes 3 of the liquid crystal display device 2 are in contact with each other. It is arranged so as to face the display device 2. In this case, in order not to damage the switching element of the inspection panel 1 and the switching element of the liquid crystal display device 2, the detection electrode 4 of the inspection panel 1 is formed to have a thickness larger than that of the switching element. In this state, when the switching element of the liquid crystal display device 2 is operated and a signal is input to the liquid crystal display device, the current from each pixel electrode 3 flows to the corresponding detection electrode 4 of the inspection panel 1. This detection current is transmitted to the signal electrode 7 via the switching element 5,
It is stored in the memory device 14 through the signal detection circuit 13 for the signal electrode 7. In the above operation, by scanning the scanning electrodes 6, the detection signals from all the detection electrodes 4 are stored in the storage device 14. A detection signal is further input from the storage device 14 to the computer 15, and the display characteristics of the liquid crystal display device 2 are accurately evaluated.

The above-mentioned inspection method is performed at the stage when the switching element matrix of the liquid crystal display device is completed in the manufacturing process of the liquid crystal display device as the inspection object. However, separately from this, even when the insulating protective film is formed on the switching element matrix of the liquid crystal display device, the inspection can be performed using the inspection device according to the present embodiment. That is, when the inspection panel 1 and the liquid crystal display device 2 are arranged so as to face each other as shown in FIG. 3, the detection electrode 4 is provided with a pixel electrode of the liquid crystal display device via an insulating protective film formed on the pixel electrode of the liquid crystal display device. Form a condenser between and. In this state, operate the switching element of the liquid crystal display device,
When a signal is input to the liquid crystal display device, a transient current or an alternating current is generated in the detection electrode of the inspection panel. Therefore, the detection current may be used as a detection signal for evaluation in the same manner as the above-described inspection method. Further, in this case, it is also possible to detect the insulation failure of the insulating protective film.

<Effects of the Invention> As is apparent from the above description, when the inspection device of the present invention is used, the conduction state of each picture element of the liquid crystal display device is detected, and the inspection of the display characteristics of the liquid crystal display device is shortened all at once. It can be done in time and accurately. Based on this inspection result, the cause of the defect can be investigated and the manufacturing process can be further improved to improve the quality. Further, by bringing each detection electrode of the inspection panel into contact with the insulating film formed on the pixel electrode of the liquid crystal display device, the detection electrode of the inspection panel is connected to the pixel electrode of the liquid crystal display device through the insulating film. This is the same as forming a capacitor between them, and when a liquid crystal display device is operated in this state and a signal is input to the liquid crystal display device, a transient current or an alternating current is generated at the detection electrode of the inspection panel. The display characteristics of the liquid crystal display device can be inspected by using it as a detection signal, and the insulation failure of the insulating film can also be detected. Further, since the inspection device of the present invention can be manufactured by utilizing the manufacturing process of the active matrix type liquid crystal display device which is the object to be inspected, it can be carried out extremely inexpensively and easily and has practical value. It is great.

[Brief description of drawings]

FIG. 1 is an overall block diagram including a control mechanism of an inspection apparatus showing one embodiment of the present invention. FIG. 2 is an enlarged plan view of a main part of the inspection panel. FIG. 3 is a schematic diagram showing an inspection method. FIG. 4 is a sectional view showing the manufacturing method. 1 ... Inspection panel, 2 ... Liquid crystal display device, 3 ... Picture element,
4 ... Detection electrode, 6 ... Scanning electrode, 7 ... Signal electrode, 13
...... Signal detection circuit, 14 …… Memory device, 15 …… Computer.

Claims (3)

[Claims] 1. An inspection device of a liquid crystal display device for inspecting characteristics of each switching element of a liquid crystal display device having a structure in which a switching element is added to each picture element arranged in an XY matrix, An inspection panel in which detection electrodes having a pitch similar to that of the element is arranged in a matrix is provided, and the detection electrodes in the matrix of the inspection panel are arranged to face each other so as to match the matrix picture elements of the liquid crystal display device. An electrode and a picture element electrode of the liquid crystal display device or an insulating film formed on the picture element electrode,
An inspection apparatus for a liquid crystal display device, characterized in that the current from each picture element is detected at once by the detection electrodes of the inspection panel. 2. A switching element is added to each detection electrode of the inspection panel, and a scanning electrode and a signal electrode having the switching element as an intersection are provided, and the scanning electrode operates by applying a voltage to the scanning electrode. The inspection device for a liquid crystal display device according to claim 1, wherein a signal obtained by the detection electrode is detected from a signal electrode via a switching element. 3. An inspection panel is manufactured by utilizing a manufacturing process of a liquid crystal display device of an object to be inspected, and matrix detection electrodes of the inspection panel are arranged so as to face each other so as to match the matrix picture elements of the liquid crystal display device. , Each detection electrode is brought into contact with a pixel electrode of the liquid crystal display device or an insulating film formed on the pixel electrode, and the current from each pixel is detected by the detection electrodes of the inspection panel to detect all the pixels at once. A method for inspecting a liquid crystal display device, comprising: