JP2005031546A - Liquid crystal display device and method for inspecting the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out highly accurate OS inspection of a p-Si type array substrate without increasing an area of a signal line driving circuit and equipment investment. <P>SOLUTION: Image signal wiring lines 33 are connected to signal lines at the rate of k signal lines (k is an integer of 3 or more) per image signal wiring line and, at the same time, diodes 34 are connected to the other end of the respective signal lines 12 at the rate of two diodes with mutually different directions per signal line. Another terminal of each of the diodes 34 is connected to each line of array substrate wiring lines 31. There are k array substrate wiring lines 31 and the array substrate wiring lines 31 different from each other are connected to each of the neighboring signal lines 12. Under this construction, the diode 34 and the image signal wiring lines 33 are respectively connected to OLB pads 25 and 23 so as to make the OS inspection of the signal line 12 and the image signal wiring lines 33 feasible, make mounting of a probing pad between the signal line 12 and the signal line driving circuit 19 unnecessary and, at the same time, make use of a probe for inspection of an a-Si type array substrate unnecessary. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device and an inspection method thereof, and more particularly to a technique for detecting a disconnection or a short circuit of a signal line.

  In general, liquid crystal display devices are lightweight, thin, and have low power consumption, and thus are used for televisions, personal digital assistants, graphic displays, and the like. In particular, matrix-type liquid crystal display devices (TFT-LCDs) that use thin film transistors (TFTs) as switching elements for each pixel have excellent high-speed response and are suitable for high-definition and high-quality display screens. It has been attracting attention as a means for realizing large-size, large-size and color imaging.

  Conventionally, as this type of liquid crystal display device, for example, a liquid crystal display device shown in a circuit diagram of FIG. 3 is known. The liquid crystal display device shown in FIG. 1 is wired on a glass array substrate 100 so that a plurality of scanning lines 11 for scanning and a plurality of signal lines 12 for image signals intersect with each other. Pixels are provided at each intersection. In each pixel, the gate of the thin film transistor 13 is connected to the scanning line 11, the source is connected to the signal line 12, and the drain is connected to the pixel electrode 14. One terminal of an auxiliary capacitor 15 is connected to the pixel electrode 14, and an auxiliary capacitor line 16 is connected to the other terminal of the auxiliary capacitor 15.

  The array substrate 100 is disposed to face the counter substrate via a liquid crystal layer (not shown), and the pixel electrode 14 is disposed to face the counter electrode on the counter substrate via the liquid crystal layer.

  Each scanning line 11 is connected to a scanning line drive circuit 18, each signal line 12 is connected to a signal line drive circuit 19, and the counter electrode is connected to a counter electrode drive circuit (not shown). A voltage corresponding to the horizontal scanning period is sequentially applied to each scanning line 11 by the scanning line driving circuit 18 from above in the figure. A voltage corresponding to the image signal is applied to each signal line 12 from the signal line driving circuit 19. As a result, the thin film transistor 13 is turned on at a timing when a voltage is applied through the scanning line 11, samples a voltage corresponding to the image signal from the signal line 12, and applies the voltage to the pixel electrode 14. The liquid crystal layer is charged with a difference between the voltage applied to the pixel electrode 14 and the voltage applied to the counter electrode from the counter electrode driving circuit, and the liquid crystal layer is driven to perform a display operation by optical response.

  This liquid crystal display device is a case where the scanning line driving circuit 18 and the signal line driving circuit 19 are formed on the array substrate 100, and a p-Si (polycrystalline silicon) type liquid crystal is selected from the type of semiconductor material used for the thin film transistor 13. It is called a display device. On the other hand, a material using a-Si (amorphous silicon) as a semiconductor material is called an a-Si liquid crystal display device. Since an a-Si liquid crystal display device has inferior transistor characteristics as compared with a p-Si liquid crystal display device, it is difficult to provide a drive circuit on the array substrate 100. Therefore, as shown in the circuit diagram of FIG. 4, only the display region composed of each pixel is formed on the array substrate of the a-Si type liquid crystal display device, and the scanning line driving circuit 18 and the signal line driving circuit 19 are formed. Not. Each of the drive circuits 18 and 19 is created separately from the array substrate 100 as a semiconductor integrated circuit (driver IC), and TAB is applied to OLB (Outer Lead Bonding) pads 21m and 22n (m and n are positive integers) of the array substrate 100. The connection is made using a technique such as (Tape Automated Bonding).

  One of the differences between the array substrate in the p-Si type and the array substrate in the a-Si type is the OLB pad. As shown in FIG. 4, in the a-Si type, the scanning line 11 is directly drawn to the OLB pad 21m, and the signal line 12 is drawn directly to the OLB pad 22n. Therefore, the number and pitch of OLB pads are equal to the number and pitch of scanning lines 11 and signal lines 12. On the other hand, as shown in FIG. 3, in the p-Si type, since the scanning line 11 and the signal line 12 are driven by the drive circuits 18 and 19 formed together on the array substrate 100, they are directly drawn out to the OLB pad. There is nothing. Input from the OLB pad is an input signal to the drive circuits 18 and 19, and the number thereof is generally about one digit smaller than the number of scanning lines 11 and signal lines 12. Therefore, the OLB pad pitch can be increased to ensure connection reliability.

  The differences in OLB pads between the p-Si type and the a-Si type are summarized in the table of FIG. Here, a case of a 10.4 inch XGA compatible liquid crystal display device that is generally used for a personal computer will be described. Compared to the a-Si type, the p-Si type is advantageous in that the prober accuracy may be low and the capital investment is small.

  Such a difference in OLB pads also affects inspection during the manufacturing process of the array substrate. In the a-Si type, when a signal line is formed during the manufacturing process of the array substrate, disconnection (open) and short circuit (short) inspection (hereinafter referred to as OS inspection) is performed. This inspection is performed by applying a predetermined voltage to the OLB pad connected to one end of the signal line and the probing pad provided at the other end, applying a predetermined voltage, and measuring the current flowing at this time. Is called. Here, if the signal line is normally formed, a predetermined current determined from the applied voltage and the resistance of the signal line is detected. If the signal line is disconnected, no current flows, so that a disconnection failure can be detected. Further, if a voltage different from that of the signal line is applied to the scanning line or the auxiliary capacitance line at the time of inspection, an abnormal current flows when the signal line is short-circuited therewith, so that a short circuit failure can be detected.

  On the other hand, there is no OS inspection in the manufacturing process of the p-Si type array substrate. This is because there is no OLB pad for applying the probe to the end of the signal line. Although inspection is performed at the final stage of the manufacturing process of the array substrate, since the pixel portion is inspected via the drive circuits 18 and 19 in the p-Si type, the S / N is poor and detection of defects in the signal line is detected. The rate is not enough.

Thus, in the p-Si type, the detection rate of defects such as signal line disconnection and short circuit is lower than that in the a-Si type. As a result, a defective array substrate is used in the cell manufacturing process, and wasteful manufacturing costs are generated. As a technique for detecting disconnection or short circuit of a signal line in the p-Si type, a technique described in Patent Document 1 is known.
JP 2003-29296 A

  In general, when an OS inspection is to be performed on a p-Si type array substrate, a pad for applying probes to both ends of a signal line is required, and this probing pad is almost the same size as an OLB pad. When this is provided between the signal line and the signal line driver circuit, the area of the signal line driver circuit is substantially increased. As a result, there is a problem that the compactness of the liquid crystal module as a product is lost. Furthermore, even if a probing pad is provided, the pitch is equal to the pitch of the signal line, and a prober for high-precision a-Si type array substrate inspection is required for inspection of the p-Si type array substrate. Become. For this reason, there also exists a problem that the amount of capital investment increases.

  The present invention has been made in view of the above, and an object of the present invention is to perform high-precision OS inspection on a p-Si type array substrate without causing an increase in the area of a signal line driving circuit or an increase in capital investment. It is an object of the present invention to provide a liquid crystal display device and an inspection method thereof.

  The liquid crystal display device according to the present invention includes a plurality of signal lines and a plurality of scanning lines wired so as to intersect with each other, a pixel provided at each intersection of the signal lines and the scanning lines, and one of the signal lines Video signal wirings connected one by one in correspondence with k signal lines (k is an integer equal to or greater than 3) at the end of each, and a selection signal for selecting one of the k signal lines A line, a diode connected to the other end of the signal line for each signal line in two different directions, and a wiring connected to the signal line via the diode, the number of the wirings being k. The different signal lines are connected to the adjacent signal lines.

  The method for inspecting a liquid crystal display device according to the present invention includes a step of applying a selection signal for selecting one of k signal lines to the liquid crystal display device to the selection signal line, Applying a predetermined voltage between the video signal wiring connected to the connected signal line and the wiring connected to the signal line via two diodes, and applying the predetermined voltage Measuring a current flowing through the signal line and the video signal wiring.

  In the present invention, the video signal wiring is connected at a ratio of one for each k signal lines, and two diodes are connected to the other end of each signal line in different directions. The diode and the video signal wiring can be connected to the OLB pad so that the OS inspection can be performed on the signal line and the video signal wiring, and it is unnecessary to provide a probing pad between the signal line and the signal line driving circuit. Therefore, it is unnecessary to use a prober for a-Si type array substrate inspection.

  In addition, video signal wiring is connected at a ratio of one to k signal lines, and one of k signal lines can be selected by a selection signal. The number of OLB pads is set to 1 / k compared to the case where video signal wiring is provided for each.

  According to the liquid crystal display device and the inspection method thereof according to the present invention, it is possible to perform high-precision OS inspection on a p-Si type array substrate without causing an increase in the area of the signal line driving circuit and an increase in capital investment Therefore, a defective array substrate is not used in the cell manufacturing process, and wasteful manufacturing costs can be reduced.

  Hereinafter, a liquid crystal display device according to an embodiment will be described with reference to the drawings.

  As shown in the circuit diagram of FIG. 1, the liquid crystal display device is wired on a glass array substrate 1 so that a plurality of scanning lines 11 for scanning and a plurality of signal lines 12 for image signals intersect, A pixel is provided at each intersection of the scanning line 11 and the signal line 12. In each pixel, the gate of the thin film transistor 13 as a switching element is connected to the scanning line 11, the source is connected to the signal line 12, and the drain is connected to the pixel electrode 14. One terminal of an auxiliary capacitor 15 is connected to the pixel electrode 14, and an auxiliary capacitor line 16 is connected to the other terminal of the auxiliary capacitor 15.

  As shown in FIG. 2, the liquid crystal layer 3 is held in the gap between the array substrate 1 and the counter substrate 2 arranged opposite to the array substrate 1, and the space between the substrates 1 and 2 is sealed with a sealing material 5. The On the surface of the counter substrate 2 on the side in contact with the liquid crystal layer 3, the counter electrode 4 is disposed so as to oppose the pixel electrode 14 on the array substrate 1.

  Each scanning line 11 is connected to a scanning line driving circuit 18, each signal line 12 is connected to a signal line driving circuit 19, and the counter electrode is connected to a counter electrode driving circuit (not shown). Each scanning line 11 is sequentially driven from the upper side of FIG. 1 by the scanning line driving circuit 18 to control switching by the thin film transistor 13. Each signal line 12 is supplied with a video signal by a signal line driving circuit 19.

  Inside the signal line driving circuit 19, video signal wirings 33 are connected to the ends of the signal lines 12 one by one corresponding to the three signal lines via the analog switch 19 b. There are n video signal lines (n is a positive integer), and there are 3n signal lines 12. Hereinafter, the video signal wiring is appropriately referred to as video signal wiring 33 (1), 33 (2),... 33 (n), and the signal lines 12 (1), 12 (2),. ) As appropriate.

  The selection signal lines 32a, 32b, 32c,... Correspond to the analog switches 19b (1), 19 (2), 19 (3),... At the gates of the analog switches 19b provided on the signal lines 12, respectively. Connected.

  Two diodes 34 are connected to the other end of each signal line 12 in two different directions. In FIG. 1, the anode terminal of the diode 34a and the cathode terminal of the diode 34b are connected to the signal line 12 (1), the anode terminal of the diode 34c and the cathode terminal of the diode 34d are connected to the signal line 12 (2), and the diode 34e. And the cathode terminal of the diode 34f are connected to the signal line 12 (3). Similarly, diodes 34a to 34f are connected to the other signal lines. These diodes 34a to 34f are connected to wirings 31a to 31f on the array substrate, respectively.

  The two control signal lines connected to the scanning line driving circuit 18 are connected to the OLB pads 21a and 21b, respectively. The selection signal lines 32a to 32c are connected to the OLB pads 22a to 22c, respectively. The video signal wirings 33 (1), 33 (2),... 33 (n) are connected to the OLB pads 23 (1), 23 (2),. The auxiliary capacitance line 16 is connected to the OLB pad 24. The on-array substrate wirings 31a to 31f are connected to the OLB pads 25a to 25f, respectively.

  In the present liquid crystal display device, an external drive circuit that supplies control signals and selection signals to the drive circuits 18 and 19 and a drive IC that supplies video signals to the signal lines 12 are provided outside the array substrate 1. These external drive circuits and drive ICs are connected to the OLB pads by TAB technology.

  Next, an inspection method for the liquid crystal display device configured as described above will be described. In this inspection method, a predetermined voltage is applied between the array substrate wiring 31 and the video signal wiring 33 through each OLB pad, and the current at that time is measured, whereby the signal line 12 and the video signal wiring 33 are measured. The presence or absence of disconnection or short circuit failure is detected.

  First, the basic function of the diode 34 will be described. A potential higher than the normal signal line potential is applied to the array substrate wiring 31a, and a potential lower than the normal signal line potential is applied to the wiring 31b. Therefore, when the signal line potential is normal, the two diodes 34a and 34b are both turned off, and no current flows through the signal line 12 (1) and the video signal wiring 33 (1). Here, a case where an abnormal voltage is generated in the signal line 12 (1) is considered. If the potential of the signal line 12 (1) becomes higher than the normal potential, the diode 34a is turned on, and a current flows between the signal line 12 (1) and the wiring on the array substrate 31a. This current continues to flow until the potential of the signal line 12 (1) returns to normal and becomes lower than the potential of the array substrate wiring 31a. Conversely, when the potential of the signal line 12 (1) becomes lower than the normal potential, the diode 34b is turned on, and a current flows between the signal line 12 (1) and the wiring on the array substrate 31b. This current continues to flow until the potential of the signal line 12 (1) returns to normal and becomes higher than the potential of the wiring on the array substrate 31b. With the above operation, the two diodes 34a, 34b protect the signal line 12 (1) from being destroyed by overvoltage by releasing the abnormal voltage generated in the signal line 12 (1) to the outside through the wiring 31 on the array substrate. is doing. The same applies to the other signal lines 12 (2), 12 (3),... 12 (3n).

  Next, a case where the OS inspection is performed on the signal line 12 and the video signal wiring 33 by the inspection method will be described. Here, the signal line 12 (1) and the video signal wiring 33 (1) will be described first as an example. When the array substrate wiring 31a is used, the potential of the wiring is made lower than the normal signal line potential, the diode 34a is turned on, and a current path from the video signal wiring 33 (1) to the array substrate wiring 31a is secured. To do. Then, a predetermined voltage is applied between the video signal wiring 33 (1) and the array substrate wiring 31a through the OLB pad 23 (1) and the OLB pad 25a using the voltage source 42a or the voltage source 42g. By measuring the current at this time using the ammeter 41a or 41g, it is detected whether the signal line 12 (1) or the video signal wiring 33 (1) is broken or short-circuited. When the disconnection occurs, the current flowing through the signal line 12 (1) and the video signal wiring 33 (1) is small, so the presence / absence of the disconnection is detected based on the amount of current. In addition, when a short circuit occurs between adjacent signal lines or video signal wirings, the current flowing through the adjacent signal lines or video signal wirings is large. The presence of a short circuit is detected by measuring the current through a diode. When the array substrate wiring 31b is used, on the contrary, the potential of the wiring is made higher than the normal signal line potential, the diode 34b is turned on, and the OS inspection is performed. The same applies to the other signal lines 12 (2), 12 (3),... 12 (3n).

  In the present liquid crystal display device, one video signal wiring 33 is connected to each of three signal lines, and the selection signals supplied to the three selection signal lines 32a to 32c are controlled to thereby control out of the three. One signal line is selected. For example, in one horizontal scanning period, the selection signal line 32a is turned on, the selection signal lines 32b and 32c are turned off, and the signal lines 12 (1), 12 (4),... 12 (3n-2 ) And a predetermined voltage is applied to the video signal wiring connected thereto, and the current is measured. In the subsequent 1/3 period, the selection signal line 32b is turned on, the selection signal lines 32a and 32c are turned off, and the signal lines 12 (2), 12 (5),... 12 (3n-1) and these are connected. A predetermined voltage is applied to the existing video signal wiring, and the current is measured. In the next ３ period, the selection signal line 32c is turned on, the selection signal lines 32a and 32b are turned off, and the signal lines 12 (3), 12 (6),... 12 (3n) and these are connected. A predetermined voltage is applied to the existing video signal wiring, and the current is measured.

  As described above, the video signal wiring 33 provided at a ratio of one for every three signal lines is connected to the OLB pad 23, so that the OLB pads 23 are provided for all the signal lines 12. In comparison, the number of OLB pads is １ ／.

  Therefore, according to the present embodiment, one video signal wiring 33 is provided for every three signal lines, and two diodes 34 are provided in different directions at the other end of each signal line. Thus, the OS inspection can be performed on the signal line and the video signal wiring in a state where the video signal wiring 33 and the diode 34 are connected to the OLB pads 23 and 25, respectively. Probing pads need not be provided, and high-precision OS inspection can be performed on p-Si type array substrates without increasing the area of the signal line drive circuit 19.

  In the present embodiment, three array substrate wirings 31 connected to the signal lines 12 via the diodes 34 are prepared, and the adjacent signal lines 12 are connected to each other by connecting different array substrate wirings 31. The power supply systems to which the signal lines 12 are connected are different, and the inspection accuracy can be improved even when the adjacent signal lines 12 are at the same potential.

  According to the present embodiment, since it is not necessary to use an a-Si type array substrate inspection prober, there is no increase in capital investment, and a low-accuracy and low-priced p-Si prober is used. An OS inspection of the array substrate can be performed.

  According to the present embodiment, the potential of the on-array substrate wiring 31 is set so that the diode 34 is turned on, and a current path is secured between the signal line 12 and the video signal wiring 33, so that In addition to detecting the presence or absence of defects by measurement, it is possible to specify whether the type of defect is a disconnection or a short circuit, which can improve inspection accuracy, so that a defective array substrate flows into the cell manufacturing process. This can be surely prevented, and wasteful manufacturing costs can be reduced.

  According to the present embodiment, the video signal wiring 33 provided at a ratio of one for every three signal lines is connected to the OLB pad 23, and one of the three signal lines is selected by the selection signal. Since the number of OLB pads is reduced to 1/3 as compared with the case where one video signal wiring 33 is provided for every signal line 12 because of the possible configuration, the number of TABs connected to the OLB pads. The manufacturing cost and product cost can be reduced.

  In the present embodiment, the video signal wiring 33 is provided at a ratio of one for every three signal lines, but 1 for every k signal lines (k is an integer of 3 or more). You may make it provide the video signal wiring 33 in the ratio of a book. In this case, k selection signal lines are prepared, and one of the k signal lines can be selected. By adopting a configuration in which the number of k is increased, the number of OLB pads and TABs can be further reduced.

It is a circuit diagram which shows the structure of the liquid crystal display device in one Embodiment. It is sectional drawing which shows the structure of the said liquid crystal display device. It is a circuit diagram which shows the structure of the conventional p-Si type liquid crystal display device. It is a circuit diagram which shows the structure of the conventional a-Si type liquid crystal display device. It is the table | surface which put together the difference between the p-Si type and a-Si type OLB pads.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Array substrate 2 ... Counter substrate 3 ... Liquid crystal layer 4 ... Counter electrode 11 ... Scanning line 12 ... Signal line 13 ... Thin-film transistor 14 ... Pixel electrode 15 ... Auxiliary capacity 16 ... Auxiliary capacity line 18 ... Scan line drive circuit 19 ... Signal line Drive circuit 19b ... Analog switches 21-25 ... OLB pads 31 ... Wiring on array substrate 32 ... Selection signal line 33 ... Video signal wiring 34 ... Diode 41 ... Ammeter 42 ... Voltage source

Claims (4)

A plurality of signal lines and a plurality of scanning lines wired to cross each other;
A pixel provided at each intersection of the signal line and the scanning line;
Video signal wiring connected to one end of the signal line one by one corresponding to k (k is an integer of 3 or more) signal lines;
a selection signal line for selecting one of k signal lines;
Two diodes connected in different directions to the other end of the signal line for each signal line;
A wiring connected to the signal line via the diode;
2. The liquid crystal display device according to claim 1, wherein there are k wirings, and different wirings are connected to the adjacent signal lines. The liquid crystal display device according to claim 1,
applying a selection signal for selecting one of k signal lines to the selection signal line;
Applying a predetermined voltage between the video signal wiring connected to the selected signal line and the wiring connected to the signal line via two diodes;
Measuring the current flowing through the signal line and video signal wiring;
A method for inspecting a liquid crystal display device, comprising:   3. The method for inspecting a liquid crystal display device according to claim 2, wherein the potential of the wiring connected to the diode is set so that the diode connected to the selected signal line is turned on. In the step of measuring the current, the signal line or the video signal wiring is disconnected or adjacent depending on the magnitude of the current flowing through each wiring connected to the adjacent signal line or video signal wiring via the diode. 4. The method for inspecting a liquid crystal display device according to claim 3, wherein a short circuit with a signal line or video signal wiring to be detected is detected.

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