KR20050041443A - Method and apparatus for testing flat panel display - Google Patents

Abstract

The present invention relates to a method and apparatus for inspecting a flat panel display device for inspecting short and open of signal wiring.

The inspection method and apparatus of the flat panel display apparatus applies a DC voltage to arc wirings, and moves a magnetic sensor on the signal wirings to which the DC voltage is applied to detect an open position of the signal wirings.

Description

Inspection method and apparatus for flat panel display device {Method and Apparatus for Testing Flat Panel Display}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel display device, and more particularly, to a method and apparatus for inspecting a flat panel display device for inspecting short and open of the flat panel display device.

In today's information society, display elements are more important than ever as visual information transfer media. Cathode ray tubes or cathode ray tubes, which are currently mainstream, have problems with weight and volume. Many kinds of flat panel displays have been developed to overcome the limitations of the cathode ray tube.

The flat panel display devices include liquid crystal display (LCD), field emission display (FED), plasma display panel (PDP), and electroluminescence (EL). Most of these are commercially available and commercially available.

Liquid crystal display devices can meet the trend of light and short and short of electronic products and mass production is improving, and are rapidly replacing cathode ray tubes in many applications.

In particular, an active matrix type liquid crystal display device that drives a liquid crystal cell using a thin film transistor (hereinafter referred to as "TFT") has the advantages of excellent image quality and low power consumption, and secures the latest mass production technology. As a result of research and development, it is rapidly developing into larger size and higher resolution.

A manufacturing process for manufacturing an active matrix liquid crystal display device is divided into a substrate cleaning, a substrate patterning process, an alignment film forming / rubbing process, a substrate bonding / liquid crystal injection process, a mounting process, an inspection process, a repair process, and the like.

In the substrate cleaning process, foreign substances contaminated on the substrate surface of the liquid crystal display device are removed with a cleaning liquid.

In the substrate patterning process, the upper substrate (color filter substrate) and the lower substrate (TFT-array substrate) are divided into patterning. A color filter, a common electrode, a black matrix, and the like are formed on the upper substrate. Signal wirings such as data wirings and gate wirings are formed on the lower substrate, and TFTs are formed at the intersections of the data wirings and the gate wirings. Is formed.

In the alignment film forming / rubbing process, an alignment film is applied to each of the upper substrate and the lower substrate, and the alignment film is rubbed with a rubbing cloth or the like.

In the substrate bonding / liquid crystal injection process, the upper substrate and the lower substrate are bonded using a sealant, the liquid crystal and the spacer are injected through the liquid crystal inlet, and then the liquid crystal inlet is sealed.

In the liquid crystal panel mounting process, a tape carrier package (TCP), in which integrated circuits such as a gate drive integrated circuit and a data drive integrated circuit, are mounted is connected to a pad portion on a substrate. In addition to the tape automated bonding method using the above-described TCP, the chip may be directly mounted on a substrate by a chip on glass (COG) method.

The inspection process includes an electrical inspection performed after various signal wiring and pixel electrodes are formed on the lower substrate, and an electrical inspection and a visual inspection performed after the substrate bonding / liquid crystal injection process. In particular, the electrical inspection process of the signal wiring and the pixel electrode of the lower substrate prior to the bonding of the substrate is very important in that the defect rate and disposal can be reduced, and the defective substrate in a relatively repairable state can be detected early.

The repair process restores the substrate that is determined to be repairable by the inspection process. Defective substrates that cannot be repaired in the inspection process are discarded.

US Patent No. 5,073, 754 discloses a method and apparatus for inspecting a short of signal wires formed on a substrate of a liquid crystal display using a magnetic sensor.

Referring to FIG. 1, the inspection apparatus disclosed in U.S. Patent No. 5,073,754 is provided with shorting bars 11, 12, 13, and 14 connected to the column wirings 16 and the row wirings 15 of the liquid crystal panel 10. A conventional precision measuring device 20 for supplying a current, a magnetic pick-up 17 and a magnetic sensor for detecting a magnetic field generated on the column wirings 16 and the row wirings 15 of the liquid crystal panel 10. 18 and an inspection controller 19 for controlling the magnetic sensor 18.

The precision measuring device 10 supplies a current to the column wirings 16 and the row wirings 15 of the liquid crystal panel 10 through the shorting bars 11, 12, 13, and 14, including a voltage source and a current source. The current flowing on the shorting bars 11, 12, 13, and 14 is detected.

The inspection controller 19 controls the magnetic sensor 18 so that the magnetic pickup 17 can scan the column wirings 16 and the row wirings 15 of the liquid crystal panel 10 and from the magnetic sensor 18. The generated current is supplied to the precision measuring device 10.

The inspection apparatus detects the current and the magnetic field generated when the column wirings 16 and the row wirings 16 of the liquid crystal panel 10 are shorted by the magnetic sensor 19 and the magnetic pickup 17. (16) and the low wirings (16) will detect the shorted position.

These inspection devices can only inspect the short in the liquid crystal display (LCD) or the field emission display (FED), whereas the applicant of the present application is the Korean Patent Application No. 2003-0028641, 2003-0028643, 2003-2003 Through -0028644, 2003-0028645, 2003-0028646, etc. has proposed a test method and apparatus that can be inspected from the short to the open.

However, the inspection method using the magnetic sensor has a disadvantage in that the sensitivity of the inspection is lowered because the interference of the magnetic field generated in the wirings in which the magnetic sensor is located and other adjacent wirings and the strength of the detected magnetic field are low.

For example, when the short test is performed on the row wires 16 as shown in FIG. 2, a high potential common voltage is applied to the first test pad 16b connected to the odd row wires 16, and the even low row is performed. The low potential common voltage is applied to the second inspection pad 16c connected to the wires 16 and the magnetic sensor 23 is moved in the direction of the arrow. At this time, the induction magnetic field generated in the low wirings 16 shorted by the current i flowing through the low wirings 16 via the shorting point 22 is detected by the magnetic sensor 23. In this short test, the current i flows only in the row wires 16 shorted via the shorting point 22, so that the number and position of the shorted row wires 16 can be known relatively easily. In FIG. 2, reference numerals '15a' and '16a' are pads connected to the column wirings 15 and the row wirings 16, respectively, and '15b' is column wiring when the column wirings 15 are inspected. It is a common pad for applying the same voltage to the field 16. Reference numerals '21a' and '21b' are ESD (Electrostatic Discharge Damage) devices for bypassing static electricity generated during the manufacturing process of the liquid crystal display toward the ground voltage source (GND), and '16d' denotes ESD protection devices ( It is a common pad for supplying the base voltage GND and the common voltage Vcom to 21a).

However, in the open inspection, it is difficult to accurately detect the location and number of open wirings due to the interference of the magnetic field. As shown in FIG. 3, an AC voltage is applied between the first and second inspection pads 16b and 16c positioned on the right side of the odd row wirings 16 and the common pad 16d connected to the left side of the row wirings 16. When the short inspection is performed on the row wires 16 while the magnetic sensor 23 is moved in the direction of the arrow, other row wires 16 except for the row wire 16 opened at the open point 30 are applied. In both cases current flows. At this time, an induced magnetic field generated in the row wirings 16 through which current flows is generated. When the magnetic sensor 23 is positioned on the open row wiring 42b as shown in FIG. 4, the low wiring line in which the magnetic fluxes φ of the induced magnetic field generated in the row wirings 42a and 42c adjacent thereto are opened. Due to the diffusion toward 42b, current flows in the coil of the magnetic sensor 23 due to the magnetic flux from the adjacent row wirings 42a and 42c, and voltage Vi is generated at both ends of the output terminal connected to the coil. In other words, on the open row wiring 42b, the magnetic sensor 23 should not generate a voltage but an unwanted voltage Vi is generated. In Fig. 4, reference numeral '41' denotes a TFT array substrate of a liquid crystal display element. The voltage Vi of the magnetic sensor 23 may be described by Faraday's law as shown in Equation 1 below.

Where 'N' is the number of turns of the coil and 'φ' is the magnetic flux.

As can be seen from Equation 1, the voltage Vi of the magnetic sensor 23 is the rate of change of the magnetic flux. The larger this is, the higher it becomes. Rate of change of magnetic flux Is affected by the frequency of the current flowing through the respective wires, the magnetic flux generated in the adjacent wires, and the speed of the magnetic sensor 23. Among these, the speed of the magnetic sensor 23 is negligibly small compared to the current generated by the frequency of the current flowing through the wirings and the magnetic flux of the adjacent wirings. The higher the frequency interference effect generated from adjacent wirings, the larger the frequency. After all, the rate of change of magnetic flux Depends on the frequency of the current flowing in the wirings. Therefore, when the AC voltage is applied to each of the wirings during the open inspection, the high frequency interference effect acting on the magnetic sensor 23 becomes larger, so that the sensitivity of the magnetic sensor 23 is inevitably lowered.

In order to eliminate noise caused by unwanted magnetic fields generated in adjacent wirings, US Pat. No. 6,118,279 discloses a filter for removing noise in a signal processing circuit. However, this method is difficult to remove the noise fundamentally, there is a problem in that the circuit cost is increased because a filter for removing the noise with a complex algorithm.

Accordingly, an object of the present invention is to provide a method and apparatus for inspecting a flat panel display device to improve the precision during short inspection and open inspection.

In order to achieve the above object, an inspection method of a flat panel display device according to an embodiment of the present invention comprises the steps of applying a DC voltage to the signal wiring; And detecting an open position of the signal wires by moving a magnetic sensor on the signal wires to which the DC voltage is applied.

The inspection method includes applying an alternating voltage to the signal wires; The method may further include detecting a short circuit position of the signal wires by moving the magnetic sensor on the signal wires to which the AC voltage is applied.

An inspection apparatus of a flat panel display device according to an embodiment of the present invention includes a DC voltage source for applying a DC voltage to the signal wires; And a magnetic sensor moving on the signal wires to which the DC voltage is applied to detect an open position of the signal wires.

According to another aspect of the present invention, a method of inspecting a flat panel display includes: a voltage source for selectively applying a DC voltage and an AC voltage to signal wires; And a magnetic sensor moving on the signal wires to which the DC voltage is applied to detect an open position of the signal wires, and detecting a short circuit position of the signal wires to move on the signal wires to which the AC voltage is applied.

The DC voltage is characterized in that the voltage between tens to hundreds [V].

The AC voltage is characterized by having a frequency of 1 [KHz] or more.

The AC voltage is characterized in that the voltage between tens to hundreds [V].

The flat panel display is a liquid crystal display device.

The magnetic sensor is characterized in that the inductive sensor.

Other objects and features of the present invention in addition to the above object will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 5 to 9.

An inspection method and apparatus for a flat panel display device according to an exemplary embodiment of the present invention include an inductive sensor, a GMR sensor (Giant magnetoreseistance sensor), an MR sensor (Magnetoreseistance sensor), a fluxgate sensor, and a TMR sensor ( Magnetic sensors such as Tunneling Magnetoreseistance sensors are used to check for shorts and openings that may occur in signal wiring of flat panel display devices. Among the magnetic sensors, an inductive sensor will be described.

Referring to FIG. 5, an inspection apparatus for a flat panel display device according to an exemplary embodiment of the present invention includes a magnetic sensor 52, a signal processing circuit 53, a voltage generator 55, and a controller 56.

The magnetic sensor 52 is implemented as a conventional inductive sensor and scans the signal wirings 51a to 51d formed on the substrate 54 while being spaced apart by a predetermined interval on the substrate 54 of the flat panel display device. The induced magnetic field generated in the wirings 51a to 51d is detected.

The flat panel display device is any one of a liquid crystal display device (LCD), a field emission display device (FED), a plasma display panel (PDP), and an electroluminescence (EL). In the following description, the flat panel display device is assumed to be a liquid crystal display device.

The signal processing circuit 53 amplifies and analog-to-digital converts the voltage Vi generated from the magnetic sensor 52 and removes the mixed noise. The output voltage of this signal processing circuit 53 is input to the measurement system and display device (not shown) as data indicating whether the signal wirings 51a to 51d are short / open.

The voltage generator 55 controls a DC voltage of several tens to several hundreds [V] under the control of the controller 56 and an AC voltage of several tens to several hundreds [V] having a frequency of 1 [KHz] or more with the signal lines 51a to 51d. Supply to the signal wirings 51a to 51d selectively.

As shown in FIG. 5, the controller 56 supplies a DC voltage to the signal wires 51a to 51d during the open check and minimizes noise due to adjacent wires on the signal wires 51a to 51d during the short check. The voltage generator 55 is controlled to supply an AC voltage to the signal wirings 51a to 51d.

6 shows step by step the control procedure of the inspection method of the flat panel display device according to the embodiment of the present invention.

Referring to FIG. 6, first, the magnetic sensor 52 and the substrate 54 are initialized at an initial position. (S1) Then, when open inspection is selected by an operator or a preset program, the voltage generator 55 controls the controller 56. The DC voltage is supplied to the signal wires 51a to 51d under the control of the power supply, and when the short check is selected (S2 and S3), the voltage generator 55 controls the signal wires 51a to 51d under the control of the controller 56. Supply AC voltage to the circuit (S2 and S3).

7 illustrates an open test in the method of inspecting a flat panel display device according to an exemplary embodiment of the present invention.

Referring to FIG. 7, the column pads 72a, the row wires 73, and the column pads 72a and row wires 73 connected to the upper ends of the column wires 72 are provided on the substrate loaded in the inspection apparatus. Low pads 73a connected to the left ends of each of the plurality of ends), ESD protection elements 74a and 74b connected to the lower ends of the column wires 72 and the right ends of the row wires 73 are formed. The second column shorting wiring 76b commonly connected to the lower ends of the column wirings 74b via the first column shorting wiring 76a and the ESD protection device 74b which are commonly connected to the column pads 72a on the substrate. ), A column common pad 71c for supplying a common voltage for inspection to the column shorting wiring 76a, a first low shorting wiring 75a commonly connected to the odd row pads 73a, and even low pads 73a. ) To the first low common pad 71a and the second low shorting line 75b for supplying the common voltage for inspection to the second low shorting line 75b and the first low shorting line 75a. A second row common pad 71b for supplying a common common voltage, a third row shorting wiring 75c and a third row commonly connected to the right ends of the row wirings 73 via the ESD protection element 74a A third row common pad 71d for supplying a common voltage for inspection to the shorting wiring 76c is formed.

The column wirings 72 are orthogonal to the row wirings 73 with an insulating layer (not shown) interposed therebetween, and are used as data wirings to which data is supplied. The row wirings 73 are used as gate wirings to which scan signals are supplied. TFTs for driving pixels are formed at the intersections of the column wirings 72 and the row wirings 73, and TFTs are turned on / off in the pixel region between the column wirings 72 and the row wirings 73. The pixel electrode to which the data voltage is selectively applied is formed by turning off.

The open inspection of the row interconnections 73 will be described on the assumption that arbitrary row interconnections 73 are disconnected at the open point 70 due to a defect in the photolithography process. In the open inspection of the row wirings 73, DC voltages of tens to hundreds [V] are applied to the first and second row common pads 71a and 71b and the third row common pad 71d and the magnetic sensor 52. ) Scans the row wirings 73 while moving at a constant speed [cm / s] along the direction of the arrow, that is, the direction crossing the row wirings 73. A current path is formed in the row wires 73 that are not disconnected by the DC voltage so that a current flows. On the contrary, since the current path is switched to any row wiring 73 disconnected at the open point 70, no current flows. Therefore, when the magnetic sensor 52 is positioned on the row wires 73 which are not disconnected, the magnetic sensor 52 detects a magnetic field generated by the current i flowing in the row wires 73 and the magnetic field 52. Generates a voltage Vi proportional to. When the magnetic sensor 52 is positioned on the disconnected row wiring 73, the magnetic sensor 52 may not detect the magnetic field because no current i flows in the row wirings 73.

When a DC voltage is applied to the row wirings 73, there is no current generating element in the magnetic sensor 52 due to the instantaneous change of the magnetic flux φ other than the speed of the magnetic sensor 52. Therefore, the magnetic sensor 52 can accurately detect the position and number of the disconnected row wiring 73 without the high-frequency interference effect that lowers the sensitivity of the magnetic sensor 52.

8 shows a short test in a method of inspecting a flat panel display device according to an embodiment of the present invention. The substrate loaded into the inspection apparatus at the time of the short inspection is substantially the same as that shown in FIG.

Referring to FIG. 8, when conductive particles fall on a substrate in a manufacturing process, the conductive particles act as short circuits 80. The short check will be described on the assumption that such a short point 80 exists between any row wirings 73. In the short test, an alternating voltage of tens to hundreds [V] is applied to the first and second row common pads 71a and 71b at a frequency of 1 [KHz] or more, and the magnetic sensor 52 is connected to the row wirings 73. The row wirings 73 are scanned while moving at a constant speed [cm / s] along the crossing direction. As a result of the experiment, the sensitivity of the magnetic sensor 52 becomes high enough to accurately detect the position and number of shorted signal wires only when the frequency of the AC voltage is set to a frequency of 1 [KHz] or more. That is, the sensitivity of the magnetic sensor 52 increases as the intensity of the magnetic flux and the rate of change of the magnetic flux increase. Since the right ends of the non-shorted row wires 73 remain in a floating state, no current path is formed. Therefore, the current i does not flow in the non-shorted row wirings 73. On the contrary, since the current path is formed in any row wires 73 shorted via the short circuit point 80, the current i flows. Therefore, when the magnetic sensor 52 is positioned on the unroute row wires 73, the magnetic sensor 52 may not detect a magnetic field generated by the current flowing in the row wires 73. When the magnetic sensor 52 is positioned on the shorted row wirings 73, the magnetic sensor 52 detects a magnetic field generated by the current flowing in the row wirings 73 and is a voltage proportional to the magnetic field ( Vi) occurs.

As described above, when an AC voltage of tens to several hundreds [V] is applied to the low wirings 73 at a frequency of 1 [KHz] or more, the sensitivity of the magnetic sensor 52 is sufficiently high. The position and number of the row wires 73 can be accurately detected.

9 illustrates a cross short test in the method of inspecting a flat panel display device according to an exemplary embodiment of the present invention. The substrate loaded into the inspection apparatus at the cross short inspection is substantially the same as that shown in FIG.

Referring to FIG. 9, in order to correctly address a pixel according to video data, column wirings 72 to which video data is supplied and row wirings 73 to which a scan signal is supplied must be maintained in an insulated state. However, cross short may be generated between the column wirings 72 and the row wirings 73 through the short point 90 due to a cause such as a loss of some of the insulating layer. Assuming that such a short point 90 exists between any row wiring 73 and column wiring 72, cross short inspection will be described. In the cross short test, an AC voltage is applied to the first and second row common pads 71a and 71b and the column common pad 71c, and the magnetic sensor 52 is fixed along the direction crossing the row wirings 73. The raw lines 73 are first scanned while moving at speed [cm / s].

As described above, the AC voltage is set to a voltage of several tens to several hundreds [V] so as to sufficiently increase the sensitivity of the magnetic sensor 52, and its frequency should be 1 [KHz] or more.

One end of the row wiring 73 and the column wiring 72 which are not cross shorted each maintain a floating state, and thus no current path is formed. Therefore, the current i does not flow through the row wires 73 and the column wires 72 that are not cross shorted. On the contrary, since the current path is formed in any row wires 73 shorted via the short point 90, the current i flows. Therefore, when the magnetic sensor 52 is positioned on the row wires 73 which are not cross shorted, the magnetic sensor 52 cannot detect the magnetic field generated by the current flowing in the row wires 73. When the magnetic sensor 52 is positioned on the row wiring 73 shorted with an arbitrary column wiring 72, the magnetic sensor 52 detects the magnetic field generated by the current flowing through the row wiring 73. Generates a voltage Vi proportional to the magnetic field. By detecting the position of the arbitrary row line 72 and the shorted row line 73 through the first scan, the column lines are moved while moving the magnetic sensor 52 in the direction crossing the column lines 72. A second scan of 72 can detect the exact location of the short point 90 on the two-dimensional rectangular coordinates.

On the other hand, the embodiment has been described assuming that the magnetic sensor 52 is moved, but the magnetic sensor 52 is fixed and the substrate may move below the magnetic sensor 52 at a constant speed. As such, the process of inspecting the substrate while moving produces substantially the same effects as those of the above-described embodiment.

As described above, the inspection method and apparatus of the flat panel display device according to the present invention can minimize the deterioration of the sensitivity of the magnetic sensor due to the high frequency interference by applying a DC voltage to the signal wirings during the open inspection and the signal wirings during the short inspection. By applying an alternating voltage of several tens to several hundreds [V], the sensitivity of the magnetic sensor is increased. As a result, the inspection method and apparatus of the flat panel display device according to the present invention can increase the precision during the short inspection and the open inspection.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. For example, although an embodiment of the present invention has described a method and apparatus capable of performing an electrical test for short and openness of signal wiring using an inductive sensor, a magnetic sensor other than an inductive sensor, that is, a fluxgate sensor A sensor, a GMR sensor (Giant Magnetoreseistance sensor), an MR sensor (Magnetoreseistance sensor), etc. may be inspected for defects in signal wiring as in the embodiment. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 is a block diagram illustrating an inspection apparatus of a flat panel display device according to the related art.

2 is a view showing a conventional short inspection method.

3 is a view showing a conventional open inspection method.

FIG. 4 is a diagram illustrating high frequency interference due to an induced magnetic field from adjacent signal wires in a conventional open test.

5 is a diagram illustrating an inspection apparatus of a flat panel display device according to an exemplary embodiment of the present invention.

6 is a flowchart showing step by step a control procedure of a method for inspecting a flat panel display device according to an exemplary embodiment of the present invention.

7 is a view showing an open inspection method according to an embodiment of the present invention.

8 is a view showing a short inspection method according to an embodiment of the present invention.

9 is a view showing a cross short inspection method according to an embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

51a to 51d, 72, 73: signal wiring 52: magnetic sensor

53: signal processing circuit 54: substrate

55: voltage generator 56: controller

70: opening point 71a to 71d, 72a, 73a: pad

74a, 74b: ESD protection elements 75a to 75c, 76a, 76b: shorting wiring

80, 90: short circuit point

Claims (14)

Applying a DC voltage to the signal wires; And detecting an open position of the signal lines by moving a magnetic sensor on the signal lines to which the DC voltage is applied. The method of claim 1, Applying an alternating voltage to the signal lines; And detecting the short circuit positions of the signal wires by moving the magnetic sensor on the signal wires to which the AC voltage is applied. The method of claim 1, And the direct current voltage is a voltage between several tens to several hundreds [V]. The method of claim 3, wherein And the AC voltage has a frequency of 1 [KHz] or more. The method of claim 3, wherein And the AC voltage is a voltage between tens and hundreds [V]. The method according to any one of claims 1 to 5, And said flat panel display device is a liquid crystal display element. A DC voltage source for applying a DC voltage to the signal wires; And a magnetic sensor which moves on the signal wires to which the DC voltage is applied and detects an open position of the signal wires. The method of claim 7, wherein And the direct current voltage is a voltage between tens and hundreds [V]. A voltage source for selectively applying a DC voltage and an AC voltage to the signal wires; And a magnetic sensor moving on the signal wires to which the DC voltage is applied to detect open positions of the signal wires, and detecting a short circuit position of the signal wires by moving on the signal wires to which the AC voltage is applied. Inspection device for flat panel display device. The method of claim 9, And the direct current voltage is a voltage between tens and hundreds [V]. The method of claim 9, And the AC voltage has a frequency of 1 [KHz] or more. The method of claim 9, And the AC voltage is a voltage between tens and hundreds [V]. The method according to any one of claims 9 to 12, And the flat panel display device is a liquid crystal display device. The method of claim 9, And said magnetic sensor is an inductive sensor.