KR20040058899A - array circuit board of Liquid Crystal Display Device and test method of thereof - Google Patents

Abstract

PURPOSE: An array substrate for an LCD(Liquid Crystal Display) and a checking method thereof are provided to possess dummy pixels formed by a plurality of TFTs(Thin Film Transistors) at an outline of the array substrate and irradiate light to the TFTs, thereby generating photo current and checking disconnection of a gate line and a data line of the array unit. CONSTITUTION: The dummy pixel(40) is comprised of the first and second TFTs(41,42). A gate line or a data line formed on an array substrate is connected to a gate electrode(G1) of the first TFT(41). The drain electrode(D1) of the first TFT(41) is connected to the drain electrode of the second TFT(42). The source electrode(S1) of the first TFT(41) is used as an output stage(43). A high voltage is applied to the gate electrode(G1) of the first TFT(41), so that the first TFT(41) is always turned on. A low voltage is applied to the gate electrode(G2) of the second TFT(42), so that the second TFT(42) is always turned off.

Description

Array circuit board of liquid crystal display device and test method of

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to an array substrate of a liquid crystal display device having a plurality of dummy pixels formed of a plurality of thin film transistors on an outer side of the array substrate, and an inspection method thereof.

In general, the driving principle of the liquid crystal display device uses the optical anisotropy and polarization of the liquid crystal. Since the liquid crystal is thin and long in structure, the liquid crystal has directivity in the arrangement of molecules, and the direction of the molecular arrangement can be controlled by artificially applying an electric field to the liquid crystal.

Accordingly, if the molecular arrangement direction of the liquid crystal is arbitrarily adjusted, the molecular arrangement of the liquid crystal is changed, and light polarized by optical anisotropy may be arbitrarily modulated to express image information. The liquid crystal may be classified into a positive liquid crystal having a positive dielectric anisotropy and a negative liquid crystal having a negative dielectric anisotropy according to an electrical property classification, and the liquid crystal molecules having a positive dielectric anisotropy may be formed of liquid crystal molecules in a direction in which an electric field is applied. The long axes are arranged in parallel, and the liquid crystal molecules having negative dielectric anisotropy are arranged in the direction in which the electric field is applied and the long axes of the liquid crystal molecules are vertical.

Currently, an active matrix LCD in which a thin film transistor and pixel electrodes connected to the thin film transistor are arranged in a matrix manner is generally used because of its excellent resolution and video performance.

1 is a view schematically showing an array substrate of a conventional liquid crystal display device.

Referring to FIG. 1, an array substrate 22 of a conventional liquid crystal display device includes an area in which each subpixel 10 is formed in a matrix to represent an image, that is, a display area 20 that is an array portion, and the subpixel ( 10 is divided into a non-display area 21, which is an outer portion of the array substrate 22, on which no substrate 10 is formed.

In this case, a thin film transistor T, which is a switching element, is positioned in a matrix form, and a gate line 13 and a data line 15 passing through the plurality of thin film transistors T are formed in the display area 20. .

In addition, the subpixel 10 is defined in a region where the gate line 13 and the data line 15 cross each other and includes a thin film transistor T, a pixel electrode (not shown), and a storage capacitor 11. The pixel electrode formed on the subpixel 10 uses a transparent conductive metal having a relatively high transmittance of light, such as indium tin oxide (ITO).

FIG. 2 is a cross-sectional view of the thin film transistor illustrated in FIG. 1.

Referring to FIG. 2, the thin film transistor includes a gate electrode 30 made of metal such as aluminum (Al), chromium (Cr), molybdenum (Mo), and a source made of metal such as chromium (Cr) or molybdenum (Mo). The electrode 32, the drain electrode 33, the semiconductor layer 34, and the impurity semiconductor layer 36 are formed. Unexplained reference numeral 31 in FIG. 2 denotes a gate insulating film, 35 denotes a protective film, and 37 denotes a pixel electrode.

In addition, the gate electrode 30 is connected to the gate line 13 of FIG. 1, the source electrode 32 is connected to the data line 15 of FIG. 1, and the drain electrode 33 is a gate. The pixel electrode is in contact with the pixel electrode formed in the area surrounded by the line 13 and the data line 15.

In the thin film transistor having such a structure, when a gate voltage is applied to the gate electrode 30 through the gate line 13, a signal voltage flowing through the data line 15 is transferred from the source electrode 32 to the drain electrode 33. It operates to be applied through the ohmic contact layer 36 and the semiconductor layer 34.

When a signal voltage is applied to the source electrode 32, a voltage is applied to the pixel electrode connected to the drain electrode 32, thereby generating a voltage difference between the pixel electrode and the common electrode. Due to the voltage difference between the pixel electrode and the common electrode, the molecular arrangement of the liquid crystal interposed therebetween is changed. As the molecular arrangement of the liquid crystal is changed, the light transmittance of the pixel is changed so that the pixel with the signal voltage is applied. Color difference of unapplied pixels occurs, and the screen of the display device is controlled by using the color difference.

In addition, the gate pads 14 and the data pads 16 connected to each of the gate lines 13 and the data lines 15 disposed in the display area may be disposed in the non-display area 21. This serves to supply a gate voltage and a signal voltage to the gate line 13 and the data line 15 described above.

When the array substrate 22 is formed as described above, the liquid crystal display device is completed through a process such as bonding with the color filter substrate and injecting the liquid crystal. The gate line formed on the array substrate 22 prior to the process may be used. 13) and a check for confirming whether or not the data line 15 is defective is preceded.

In the conventional case, the gate pin and the data pin of the array test equipment are respectively connected to the respective gate pad 14 and the data pad 15 to check the line failure, and the array test equipment is connected to each gate pin and the data pin. An AC voltage was applied to each line to determine line open defects according to the amount of charge of each pixel connected to each line.

However, this conventional line open inspection method has a disadvantage in that the measurement time for inspection is long because the amount of charge of each pixel is relatively small, and is also vulnerable to noise.

According to an embodiment of the present invention, dummy pixels formed of a plurality of thin film transistors are formed at an outer portion of an array substrate, and the gate lines and data lines of the array unit are inspected for disconnection by irradiating light to the thin film transistors to generate a photo current. It is an object of the present invention to provide an array substrate of a liquid crystal display and an inspection method thereof.

1 is a view schematically showing an array substrate of a conventional liquid crystal display device.

2 is a cross-sectional view of the thin film transistor shown in FIG.

3 is a schematic view of an array substrate of a liquid crystal display device according to the present invention;

4 is a diagram illustrating a structure of a dummy pixel according to an embodiment of the present invention shown in FIG. 3.

5 is a diagram illustrating a structure of a dummy pixel according to another exemplary embodiment of the present invention.

6 is a diagram illustrating a structure of a dummy pixel according to another embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: subpixel 13: gate line

14 gate pad 15 data line

16: data pad 20: display area

21: non-display area 22, 22 ': array substrate

30, 40, 50, 60: dummy pixels 41, 51, 61: first thin film transistor

42, 52, 62: second thin film transistor 43, 54, 65: output terminal

53, 63: 3rd thin film transistor 64: capacitor

In order to achieve the above object, an array substrate of a liquid crystal display according to the present invention includes a display area in which a plurality of subpixels are configured in a matrix form and light is selectively transmitted through the subpixels, and an outer portion of the display area. The array substrate of the liquid crystal display device, which is formed and divided into a non-display area through which light is transmitted, is characterized in that a plurality of dummy pixels including a plurality of thin film transistors are formed in the non-display area.

Here, the subpixels are defined by being surrounded by a plurality of gate lines and data lines formed on the array substrate, and the dummy pixels are areas in which a pad portion for supplying a signal to a gate line and / or a data line of the non-display area is formed. And the dummy pixels are connected by the same gate line as the subpixels in the display area or by the same data line.

The dummy pixel includes first and second thin film transistors, a gate line or a data line formed on the array substrate is connected to a gate electrode of the first thin film transistor, and a drain electrode of the first thin film transistor is connected to the dummy pixel. It is connected to the drain electrode of the second thin film transistor, characterized in that the source electrode of the first thin film transistor as an output terminal.

In addition, a third thin film transistor is further provided between the first thin film transistor and the second thin film transistor, wherein the drain electrode of the first thin film transistor and the drain electrode of the third thin film transistor are connected, and the second thin film transistor is connected. The drain electrode and the gate electrode of the third thin film transistor are connected, and the source electrode of the third thin film transistor is connected to the source electrode of the second thin film transistor.

In addition, a capacitor is inserted between the drain electrode of the second thin film transistor and the gate electrode of the third thin film transistor.

In addition, the array substrate inspection method of the liquid crystal display device according to the present invention in order to achieve the above object, in the array substrate for a liquid crystal display device according to the present invention described above to light the second thin film transistor provided in the dummy pixel. And measuring a signal output to the source electrode of the first thin film transistor provided in the dummy pixel.

Herein, the step is sequentially performed on all dummy pixels formed on the array substrate, and the signal output to the source electrode of the first thin film transistor is a photocurrent generated by shining light on the second thin film transistor or a predetermined amount. Characterized in that the signal by the DC voltage.

In addition, a high voltage is applied to the gate electrode of the first thin film transistor provided in the dummy pixel so that the first thin film transistor is always on, and a low voltage is applied to the gate electrode of the second thin film transistor so that the second thin film transistor is always turned off. It is characterized by applying.

According to the present invention, since there is no direct contact with the substrate by inspecting the disconnection of the line using light, there is an advantage of reducing the risk of defects, and can easily and efficiently inspect the disconnection of the line.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view schematically showing an array substrate of a liquid crystal display according to the present invention.

Referring to FIG. 3, the array substrate 22 ′ of the liquid crystal display according to the present invention has a display area in which a plurality of sub pixels 10 are configured in a matrix and light is selectively transmitted through the sub pixels 10. 20 and a non-display area 21 formed at an outer portion of the display area 20 to which light is impermeable, and particularly, a dummy pixel composed of a plurality of thin film transistors in the non-display area 21. 30) is characterized in that a large number is formed.

In this case, the thin film transistor T, which is a switching element, is positioned in a matrix form, and the gate line 13 and the data line 15 passing through the plurality of thin film transistors are formed in the display area 20.

In addition, the subpixel 10 is defined in a region where the gate line 13 and the data line 15 cross each other and includes a thin film transistor T, a pixel electrode (not shown), and a storage capacitor 11. The pixel electrode formed on the subpixel 10 uses a transparent conductive metal having a relatively high transmittance of light, such as indium tin oxide (ITO).

In addition, the gate pads 14 and the data pads 16 connected to the gate lines 13 and the data lines 15 disposed in the display area 20 may be partially disposed in the non-display area 21. And a gate voltage and a signal voltage to the gate line 13 and the data line 15.

In addition, the dummy pixels 30 may be formed in the non-display area 21 opposite to areas in which pads 14 and 16 are formed to supply signals to the gate line 13 and / or the data line 15. The dummy pixels 30 are connected by the same gate line 13 to the subpixels 10 in the display area 20 or by the same data line 15.

As described above, forming a plurality of dummy pixels 30 in the array substrate 22 'according to the present invention makes it easy to disconnect the gate / data lines 13 and 15 of the array substrate 22'. This is because the inspection can be performed efficiently. Hereinafter, the structure and operation of the dummy pixel 30 will be described.

4 is a diagram illustrating a structure of a dummy pixel according to an embodiment of the present invention shown in FIG. 3.

Referring to FIG. 4, the structure and operation of the dummy pixel will be described. The dummy pixel 40 includes first and second thin film transistors 41 and 42, and the array substrate 22 ′ in FIG. ), The gate line 13 or the data line 15 is connected to the gate electrode G1 of the first thin film transistor 41, and the drain electrode D1 of the first thin film transistor 41 is connected to the gate line G1. It is connected to the drain electrode D2 of the second thin film transistor 42, and the source electrode S1 of the first thin film transistor 41 is characterized in that the output terminal 43.

Here, a high voltage is applied to the gate electrode G1 of the first thin film transistor 41 provided in the dummy pixel 40 so that the first thin film transistor 41 is always on, and the second thin film transistor is used. A low voltage is applied to the gate electrode G2 of 42 so that the second thin film transistor 42 is always turned off.

That is, the gate electrode G1 of the first thin film transistor 41 is connected to the gate line G13 connected to the gate electrode G1 of the first thin film transistor 41 or the data line 15 of FIG. 3. A positive DC voltage equal to or greater than the gate high voltage Vgh is applied, and a gate low voltage Vgl of the gate electrode 42 is applied to the gate electrode G2 of the second thin film transistor 42. Apply a negative DC voltage equal to or less than In addition, a predetermined positive DC voltage Vds is applied to the source electrode S2 of the second thin film transistor 42.

When the voltage is applied in this way, the first thin film transistor 41 is always kept on unless the gate line 13 or the data line 15 is disconnected and the voltage is cut off. The two thin film transistors 42 are always in an off state.

In this case, when light is emitted to the second thin film transistor 42, light absorption occurs in a semiconductor layer, for example, an amorphous silicon material, in the second thin film transistor 42, resulting in a photo current. Is generated.

Accordingly, although the second thin film transistor 42 is in an off state, the photocurrent flows to the drain electrode D2 of the second thin film transistor 42, which eventually causes the first thin film transistor 41 to flow. The output terminal 43 is output to the source electrode S1.

That is, the drain electrode D2 of the second thin film transistor 42 is connected to the drain electrode D1 of the first thin film transistor 41, so that the photocurrent is a drain electrode of the first thin film transistor 41. D1), and since the first thin film transistor 41 is always in an on state, the photocurrent flowing into the drain electrode D1 of the first thin film transistor 41 eventually reaches the first thin film transistor. It is output to the source electrode S1 of 41.

Therefore, when the gate line 13 or the data line 15 is not disconnected, light is emitted to the second thin film transistor 42 so that a photo current is necessarily a source electrode S1 of the first thin film transistor 41. Should be detected from

Accordingly, whether the gate line 13 or the data line 15 is disconnected through the dummy pixel 40 can be easily and efficiently inspected.

5 is a diagram illustrating a structure of a dummy pixel according to another exemplary embodiment of the present invention.

Referring to FIG. 5, the third thin film transistor is further disposed between the first thin film transistor and the second thin film transistor with respect to the structure of the dummy pixel 40 illustrated in FIG. 4, that is, the first thin film transistor and the second transistor. It is characterized by the provision.

At this time, the drain electrode D1 of the first thin film transistor 51 and the drain electrode D3 of the third thin film transistor 53 are connected, and the drain electrode D2 of the second thin film transistor 52 and the The gate electrode G3 of the three thin film transistor 53 is connected, and the source electrode S3 of the third thin film transistor 53 is connected to the source electrode S2 of the second thin film transistor 52.

The third thin film transistor 53 is additionally provided in order to overcome the deterioration in the detection capability when measuring the light current because the intensity of the photocurrent is weak.

That is, in such a structure, when light is emitted to the second thin film transistor 52, a photocurrent is generated and flows into the drain electrode D2 of the second thin film transistor 52, and the drain electrode D2 is Since the third thin film transistor 53 is connected to the gate electrode G3 of the third thin film transistor 53, the third thin film transistor 53 is turned on by the photocurrent.

Accordingly, a predetermined positive DC voltage Vds input to the source electrode S2 of the second thin film transistor 52 and the source electrode S3 of the third thin film transistor 53 is equal to the first electrode. The ON of the 3 thin film transistor 53 flows into the drain electrode D3 of the third thin film transistor 53, which flows into the drain electrode D1 of the first thin film transistor 51 and eventually enters the drain electrode D1. The output terminal 54 is output to the source electrode S1 of the first thin film transistor 51.

That is, the drain electrode D3 of the third thin film transistor 53 is connected to the drain electrode D1 of the first thin film transistor 51 so that the predetermined positive DC voltage Vds is The first thin film transistor 51 flows into the drain electrode D1 of the first thin film transistor 51, and the first thin film transistor 51 is always in an on state, thereby eventually draining the drain electrode D1 of the first thin film transistor 51. The voltage Vds of the positive amount introduced into the () is output to the source electrode S1 of the first thin film transistor 51.

Therefore, when the gate line 13 or the data line 15 is not disconnected, when the light is emitted to the second thin film transistor 52, the Vds must be the source electrode S1 of the first thin film transistor 51. Should be detected from

Accordingly, disconnection of each gate line 13 or data line 15 can be easily and efficiently checked through the dummy pixel 50.

6 is a diagram illustrating a structure of a dummy pixel according to another embodiment of the present invention.

Referring to FIG. 6, this is the second thin film transistor in the structure of the dummy pixel illustrated in FIG. 5, that is, the first thin film transistor 61, the second transistor 62, and the third thin film transistor 63 are provided. A capacitor 64 is inserted between the drain electrode D2 of 62 and the gate electrode G3 of the third thin film transistor 63.

This enables voltage accumulation until the gate G3 of the third thin film transistor 63 is turned on, thereby enabling a more stable operation.

Since the operation of the dummy pixel 60 illustrated in FIG. 6 is the same as that of the dummy pixel 50 illustrated in FIG. 5, a description thereof will be omitted.

3 to 6, the array substrate 22 of the liquid crystal display according to the present invention illuminates the dummy pixels 30, 40, 50, and 60, thereby illuminating the dummy pixels 30, 40, 50, and the like. The disconnection of the gate line 13 or the data line 15 connected to 60 may be checked.

That is, for all dummy pixels formed on the array substrate, light is emitted to the second thin film transistor provided in the dummy pixel, and then the signal output to the source electrode of the first thin film transistor provided in the dummy pixel is measured. By sequentially performing, the gate line and the data line of the array substrate can be inspected efficiently.

As described above, according to the array substrate and the inspection method of the liquid crystal display device according to the present invention, since there is no direct contact with the substrate by inspecting the disconnection of lines using light, the possibility of defects is reduced, and the presence of disconnection of the lines is reduced. There is an advantage that can be inspected easily and efficiently.

Claims (10)

An array of liquid crystal display devices comprising a plurality of subpixels formed in a matrix and divided into a display area in which light is selectively transmitted through the subpixels, and a non-display area formed in an outer portion of the display area to transmit light. In the substrate, And a plurality of dummy pixels including a plurality of thin film transistors are formed in the non-display area. The method of claim 1, The subpixels are defined by a plurality of gate lines and data lines formed on the array substrate, and the dummy pixels are opposite to a region where a pad portion for supplying a signal to a gate line and / or a data line of the non-display area is formed. An array substrate of a liquid crystal display device, characterized in that formed in the region. The method of claim 2, And the dummy pixels are connected by the same gate line as the subpixels in the display area or by the same data line. The method of claim 1, The dummy pixel includes first and second thin film transistors, a gate line or a data line formed on the array substrate is connected to a gate electrode of the first thin film transistor, and the drain electrode of the first thin film transistor is connected to the first thin film transistor. And a source electrode of the first thin film transistor, the output electrode being connected to the drain electrode of the two thin film transistor. The method of claim 4, wherein A third thin film transistor is further provided between the first thin film transistor and the second thin film transistor, wherein the drain electrode of the first thin film transistor and the drain electrode of the third thin film transistor are connected, and the drain of the second thin film transistor is connected. And an electrode and a gate electrode of the third thin film transistor are connected, and a source electrode of the third thin film transistor is connected to a source electrode of the second thin film transistor. The method of claim 5, And a capacitor is inserted between the drain electrode of the second thin film transistor and the gate electrode of the third thin film transistor. A method of manufacturing a liquid crystal display device according to any one of claims 1 to 6, the method comprising: illuminating a second thin film transistor provided in the dummy pixel; And measuring a signal output to a source electrode of a first thin film transistor provided in the dummy pixel. The method of claim 7, wherein And the inspection method is sequentially performed for all dummy pixels formed on the array substrate. The method of claim 7, wherein And the signal output to the source electrode of the first thin film transistor is a signal caused by a photocurrent generated by shining light on the second thin film transistor or a predetermined positive DC voltage. The method of claim 7, wherein A high voltage is applied to the gate electrode of the first thin film transistor provided in the dummy pixel so that the first thin film transistor is always on, and a low voltage is applied to the gate electrode of the second thin film transistor so that the second thin film transistor is always turned off. An array substrate inspection method of a liquid crystal display device.