JP4292770B2 - Leak inspection apparatus and leak inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a leak inspection apparatus and leak inspection method suitable for leak inspection of an active matrix liquid crystal panel or the like.
[0002]
[Prior art]
In general, an electro-optical device, for example, a liquid crystal device that performs predetermined display using liquid crystal as an electro-optical material has a configuration in which liquid crystal is sandwiched between a pair of substrates. Among these, in an electro-optical device such as an active matrix driving type liquid crystal device by TFT driving, TFD driving, etc., at each intersection of a large number of scanning lines (gate lines) and data lines (source lines) arranged vertically and horizontally. Correspondingly, a pixel electrode and a switching element are provided on a substrate (active matrix substrate).
[0003]
A scanning signal is sequentially supplied to each scanning line from a scanning line driving circuit. On the other hand, the image signal is supplied to the data line by the sampling circuit driven by the data line driving circuit. That is, the data line driving circuit is configured to supply the sampling circuit driving signal to the sampling circuit that samples the image signal on the image signal line for each data line in parallel with the sequential supply operation of the scanning signal. Yes.
[0004]
The data line driving circuit generally includes a plurality of latch circuits (shift register circuits), sequentially shifts a transfer signal supplied at the beginning of a horizontal scanning period according to a clock signal, and outputs this as a sampling signal. Similarly, the scanning line driving circuit includes a plurality of latch circuits, and sequentially shifts the transfer signal supplied at the beginning of the vertical scanning period according to the clock signal, and outputs this as the scanning signal. It is. The sampling circuit includes a sampling switch provided for each data line, samples an image signal supplied from the outside according to a sampling signal from the data line driving circuit, and supplies it to each data line. is there.
[0005]
A switching element such as a TFT element is turned on by an on signal supplied to the gate line, and an image signal supplied via the source line is written to the pixel electrode. As a result, a voltage based on the image signal is applied to the liquid crystal device between the pixel electrode and the counter electrode to change the arrangement of the liquid crystal molecules. In this way, the transmittance of the pixel is changed, and light passing through the pixel electrode and the liquid crystal layer is changed according to the image signal to perform image display. In order to improve the voltage holding characteristic in the liquid crystal layer and enable image display with a high contrast ratio, an additional capacitor is usually employed.
[0006]
As a cause of the failure of the liquid crystal device provided with such an active matrix substrate, there are a leakage failure between a gate and a source, a leakage failure of an additional capacitor, a leakage failure between a gate line and a capacitance line, and the like. As a method for detecting such a defect of the liquid crystal panel, there is a method disclosed in Patent Document 1, for example.
[0007]
As another inspection method, there is a method in which an inspection voltage is applied to a video line and a gate line. In this method, for example, 5V is adopted as the inspection voltage applied to the video line. On the other hand, for example, 17V is adopted as a voltage for inspection applied to the gate line. Note that the capacitor line is a line having a voltage of 0 V. Such a leak defect is detected by applying a test voltage to the video line and the gate line connected to the source line, and the current flowing in the video line and the gate line at this time. It is performed in the panel inspection to detect Connected to. In this case, the potential difference between the gate and the source is 12 V, and a reliable inspection for a leak failure between the gate and the source is possible. Further, when this inspection voltage is used, the potential difference between the gate line and the capacitor line is 17 V, and a short circuit between the gate line and the capacitor line can be reliably inspected.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-159997
[0009]
[Problems to be solved by the invention]
However, with this inspection voltage, the inspection voltage applied between the terminals of the additional capacitor is set to a relatively small potential difference of 5V. Therefore, it is not always possible to reliably detect a leakage failure of the additional capacitor in the panel inspection. For example, in actual use, a voltage higher than 5V may be applied to the video line. In this case, it is conceivable that a leakage failure of the additional capacity that could not be found during the inspection occurs in actual use.
[0010]
It should be noted that simply increasing the inspection voltage applied to the video line reduces the potential difference between the gate and the source, and the leak failure between the gate and the source cannot be reliably detected. .
[0011]
The present invention has been made in view of such a problem, and a leak inspection apparatus and a leak that can reliably detect a leakage defect of an active matrix substrate by setting two or more voltages as inspection voltages. The purpose is to provide an inspection method.
[0012]
[Means for Solving the Problems]
The leak inspection method according to the present invention includes a plurality of scanning lines and a plurality of source lines, a switching element provided corresponding to an intersection of the scanning lines and the source line, and between the switching element and a predetermined common potential. A first voltage application process for applying an inspection scanning voltage for inspection to the scanning line of the matrix substrate having an additional capacitor connected to the first capacitor, and a first inspection source voltage for inspection to the source line. In the first voltage application process for applying the first voltage and the first inspection mode by the first and second voltage application processes, a first current for detecting the current flowing through the source line and the current flowing through the scanning line is detected. A current detection process; a third voltage application process for applying a second voltage different from the first voltage, which is a test source voltage for testing; and applying the first and third voltages to the source line. By processing In the second inspection mode, a leakage current of the switching element and the second current detection process for detecting the current flowing through the source line and the current flowing through the scanning line, and the first and second current detection processes, and And a determination process for determining a leakage failure of the additional capacity.
[0013]
According to such a configuration, an inspection scanning voltage for inspection is applied to the scanning line by the first voltage application process, the second voltage application process, and the third voltage application process, and the source line is applied to the source line. A first voltage that is an inspection source voltage for inspection or a second voltage different from the first voltage is applied. In the first inspection mode using the inspection scanning voltage and the first voltage, a first current detection process for detecting the current flowing through the source line and the current flowing through the scanning line is performed. Further, in the second inspection mode using the inspection scanning voltage and the second voltage, a second current detection process for detecting the current flowing through the source line and the current flowing through the scanning line is performed. If a leakage failure of the switching element has occurred, current may flow through the source line and the scanning line in the first and second inspection modes, and if a leakage failure of the additional capacitor has occurred. It is conceivable that a current flows through the source line. Therefore, the first and second current detection processes in the first and second inspection modes can determine the leakage failure of the switching element and the leakage failure of the additional capacitor. In this case, the first voltage and the second voltage are different from each other and are applied to the setting of the voltage applied to the switching element and the additional capacitor between the first inspection mode and the second inspection mode. The voltage setting can be changed independently. As a result, in the first inspection mode and the second inspection mode, it is possible to set the optimum voltage for determining the leakage failure of the switching element and the optimum voltage setting for determining the leakage failure of the additional capacitor. Thus, it is possible to reliably determine a leak failure.
[0014]
The first voltage is the inspection source voltage for detecting a leakage failure of the switching element, and the second voltage is the inspection source for detecting a leakage failure of the additional capacitor. A difference between the first voltage and the scanning voltage for inspection is greater than the second voltage, and the second voltage is greater than the first voltage with respect to the common potential. It is characterized by that.
[0015]
According to such a configuration, the difference between the first voltage used in the first inspection mode and the inspection scanning voltage is larger than the second voltage. Thereby, in the first inspection mode, the voltage applied to the switching element is large, and it is easy to determine the leakage failure. On the other hand, the difference between the second voltage used in the second inspection mode and the common potential is larger than that of the first voltage. Thereby, in the second inspection mode, the voltage applied to the additional capacitor is large, and it is easy to determine the leakage failure.
[0016]
Further, the switching element is a transistor formed by a semiconductor process on the matrix substrate, and the determination process includes a leak failure between the gate and the source of the transistor and the drain of the transistor and the predetermined common potential. It is characterized by determining a leakage failure of the additional capacitor connected between them.
[0017]
According to such a configuration, a leak failure between the gate and the source of the transistor is determined by the first inspection mode, and a leakage failure of the additional capacitor is determined by the second inspection mode. In making these determinations, optimum voltage settings are performed in the first inspection mode and the second inspection mode, respectively.
[0018]
The plurality of source lines are connected to a video line to which an image signal is supplied, and the first and second current detection processes detect the current flowing through the video line, thereby detecting the current in the source line. It is characterized by detecting a flowing current.
[0019]
According to such a configuration, it is not necessary to detect the currents flowing through the plurality of source lines, and only the currents flowing through the video lines need to be detected, and it is easy to determine whether the product is good or defective.
[0020]
In the third voltage application process, a voltage value based on a level of an image signal supplied to the video line is set as the second voltage which is the inspection source voltage.
[0021]
According to such a configuration, when the matrix substrate is used for an image signal, it is possible to determine a leakage defect of the additional capacity based on the same determination criteria as when an image signal at the time of actual use is input.
[0022]
In addition, a leak inspection apparatus according to the present invention includes a plurality of scanning lines and a plurality of source lines, a switching element provided corresponding to an intersection of the scanning lines and the source line, the switching element and a predetermined common potential, A first current detecting means for detecting a current flowing in the source line of the matrix substrate having an additional capacitor connected between the second current detecting means, a second current detecting means for detecting a current flowing in the scanning line, and the scanning A first voltage applying means for applying an inspection scanning voltage for inspection to the line; a second voltage applying means for applying an inspection source voltage for inspection to the source line; and the second voltage applying means. While switching two or more types of the inspection source voltage, the switching element and the additional capacitor are determined to have a leakage defect based on the detection results of the first and second current detection means. Characterized by comprising a test control unit that.
[0023]
According to such a configuration, the scanning voltage for inspection is applied to the scanning line by the first voltage applying unit. The inspection control means applies a first voltage, which is a source voltage for inspection, or a second voltage different from the first voltage, to the source line by the first or second voltage applying means. The first current detection unit detects a current flowing through the source line, and the second current detection unit detects a current flowing through the scanning line. The voltage applied to the switching element changes when the source voltage and the first voltage are used, and when the source voltage and the second voltage are used, and the voltage applied to the additional capacitor also changes. To do. As a result, the optimum voltage setting for determining the leakage failure of the switching element and the optimal voltage setting for determining the leakage failure of the additional capacitor can be performed, and the reliable leakage failure can be determined.
[0024]
Further, the inspection control means generates a first voltage as the inspection source voltage for detecting a leakage failure of the switching element, and as the inspection source voltage for detecting a leakage failure of the additional capacitor. A second voltage is generated, and the difference between the first voltage and the inspection scan voltage is larger than the second voltage, and the second voltage is different from the common potential with the first voltage. It is characterized by being larger than.
[0025]
According to such a configuration, the difference between the first voltage and the scanning voltage for inspection is larger than the second voltage. Thereby, in this case, the voltage applied to the switching element is large, and it is easy to determine the leakage failure. On the other hand, the difference between the second voltage and the common potential is larger than that of the first voltage. Thereby, in this case, the voltage applied to the additional capacitor is large, and it is easy to determine the leakage failure.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram for explaining a leak inspection apparatus according to a first embodiment of the present invention. This embodiment is an example applied to a liquid crystal panel using an active matrix substrate as a panel to be inspected. FIG. 2 is a perspective view showing a configuration of a liquid crystal panel to be inspected, and FIG. 3 is a cross-sectional view taken along line AA ′ of FIG.
[0027]
The liquid crystal panel to be inspected has a configuration in which an element substrate and a counter substrate are attached to each other with a certain gap therebetween, and liquid crystal as an electro-optic material is sandwiched between the gaps. A transparent substrate such as a glass substrate is used as the element substrate and the counter substrate, and a peripheral driving circuit and the like are formed on the element substrate together with transistors for driving pixels.
[0028]
First, a liquid crystal panel to be inspected will be described with reference to FIGS.
[0029]
2 and 3, the liquid crystal panel 100 is a seal in which an element substrate 101 on which various elements, pixel electrodes 118, and the like are formed, and a counter substrate 102 on which a counter electrode 108 and the like are provided include spacers (not shown). The material 104 is bonded so that the electrode forming surfaces face each other while maintaining a certain gap, and a TN (Twisted Nematic) type liquid crystal 105, for example, is sealed in the gap as an electro-optical material. .
[0030]
Glass, a semiconductor, quartz, or the like is used for the element substrate 101, but glass or the like is used for the counter substrate 102. When an opaque substrate is used as the element substrate 101, it is used as a reflective type instead of a transmissive type. Further, the sealant 104 is formed along the periphery of the counter substrate 102, but a part of the sealant 104 is opened to enclose the liquid crystal 105. For this reason, after the liquid crystal 105 is sealed, the opening is sealed with the sealing material 106.
[0031]
An X driver (X driver 500 in FIG. 1) is formed in a region 140 on the opposite surface of the element substrate 101 and on the outer side of the sealing material 104 to output a sampling signal. Further, an image signal line, a sampling circuit, or the like may be formed in a region 150 in the vicinity where the sealant 104 is formed on one side. On the other hand, a plurality of mounting terminals 107 are formed on the outer peripheral portion of this side, and various signals are input from an external circuit (not shown).
[0032]
Further, Y drivers (Y drivers 400 in FIG. 1) are formed in the two side regions 130 adjacent to one side, respectively, so that the scanning lines are driven from both sides. Note that if the delay of the scanning signal supplied to the scanning line is not a problem, a configuration in which only one Y driver is formed on one side may be employed.
[0033]
On the other hand, the counter electrode 108 provided on the counter substrate 102 is configured to be electrically connected to the element substrate 101 by a conductive material in at least one of the four corners of the bonding portion with the element substrate 101.
[0034]
Although not particularly illustrated, the counter substrate 102 is provided with a colored layer (color filter) in a region facing the pixel electrode 118 as necessary. However, it is not necessary to form a colored layer on the counter substrate 102 when applied to a color light modulation application like a double-plate projector described later.
[0035]
On the opposing surfaces of the element substrate 101 and the counter substrate 102, a rubbing alignment film (not shown in FIG. 3) is provided. Further, polarizers (not shown) corresponding to the alignment direction of the alignment film are provided on the back sides of the substrates 101 and 102, respectively. In FIG. 3, the counter electrode 108, the pixel electrode 118, the mounting terminal 107, and the like have a thickness, but this is a convenient measure for indicating the formation position. Thin enough to ignore the substrate.
[0036]
In FIG. 1, the liquid crystal panel shown in FIGS. 2 and 3 is configured by parts other than the video line ammeter 124, the gate line ammeter 125, the inspection voltage generation circuit 126, and the inspection voltage control circuit 127. Note that FIG. 1 shows only one pixel among a plurality of pixels formed in a matrix. Actually, the video line ammeter 124, the gate line ammeter 125, the inspection voltage generation circuit 126, and the inspection voltage control circuit 127 are connected to predetermined terminals in the mounting terminal 107.
[0037]
In the element substrate, as shown in FIG. 1, the liquid crystal panel 100 is formed by arranging a plurality of scanning lines 112 in parallel along the X direction, and along the Y direction orthogonal thereto. A plurality of source lines 114 are formed in parallel. At each intersection of the scanning line 112 and the source line 114, the gate electrode of the TFT 116 serving as a switching element for controlling each pixel is connected to the scanning line 112, while the source electrode of the TFT 116 is connected to the source line. 114 and the drain electrode of the TFT 116 is connected to the pixel electrode 118.
[0038]
Each pixel includes a pixel electrode 118, a common electrode 108 (potential LCCOM) formed on the counter substrate, and a liquid crystal sandwiched between the two electrodes. Corresponding to each intersection, they are arranged in a matrix. In addition, in order to improve the voltage holding characteristics in the liquid crystal layer and enable image display with a high contrast ratio, for each pixel, the liquid crystal sandwiched between the pixel electrode 118 and the common electrode is electrically viewed. An additional capacitor 119 is formed in parallel. That is, the additional capacitor 119 is electrically connected between the drain of the TFT 116 and the common potential line (capacitor line) 120.
[0039]
The X driver 500 outputs the sampling signals S1 to Sn in a predetermined order by sequentially shifting the transfer start pulse DX supplied at the beginning of the horizontal scanning period according to the clock signal CLX.
Such sampling signals must be generated exclusively from each other. However, the sampling signals may be output overlapping for some reason. Then, an image signal that should be sampled on a certain data line is also sampled on a data line adjacent thereto. As a result, so-called ghost or crosstalk occurs, which causes a problem that display quality is deteriorated.
[0040]
Therefore, in order to prevent the sampling signals from overlapping, an enable circuit (not shown) is introduced in the X driver 500. The enable circuit is an enable signal called an enable signal so that the sampling circuit drive signals that precede and follow are partially overlapped on the time axis and the sampling switch does not sample according to these signals. This is a technique of narrowing the pulse width of each sampling circuit drive signal to the pulse width of the enable signal by taking the logical product of the clock signal of the above and each sampling circuit drive signal.
[0041]
By limiting the pulse width in this way, a slight time interval is set as a time margin between two successive sampling circuit drive signals. For this reason, even with high-frequency driving, adverse effects such as on-resistance, wiring resistance, time constant, capacitance, and delay time in active elements such as TFTs and various wirings that constitute sampling circuits, X drivers, etc. are relatively increased. Even so, this adverse effect can be partially or completely absorbed by the time margin described above.
[0042]
As a result, when the image signal is not phase-expanded, it is connected between adjacent data lines, or when the image signal is phase-expanded, it is connected to the same image signal and driven before and after. It is possible to efficiently prevent so-called crosstalk and ghosting between the data lines.
[0043]
The X driver 500 uses the input enable signal (pulse width limit signal) ENB to reliably prevent adjacent sampling signals S1 to Sn from simultaneously becoming high level (hereinafter referred to as H level). It has become.
[0044]
Sampling signals S1 to Sn from the X driver 500 are applied to the gates of n switching transistors 122 that connect the video line 113 and the n source lines 114, respectively. The transistor 122 is turned on by an H level sampling signal and supplies a signal of the video line 113 to each source line 114. Note that the source line 114 is connected to the common signal line NRS through the transistor 123. The transistor 123 is turned on by a signal NRG applied to the gate, and supplies the voltage of the common signal line NRS to one end of the source line 114. Note that when the transistor 123 is turned off by the signal NRG, the source line 114 can be put in a floating state.
[0045]
The Y driver 400 is basically the same as the X driver 500 except that the output signal extraction direction and the input signal are different. That is, the Y driver 400 is an arrangement in which the X driver 500 is rotated 90 degrees counterclockwise, and, as shown in FIG. 1, a transfer start pulse pulse DY is input instead of the pulse DX, and the clock signal CLX is Instead, the clock signal CLY is input every horizontal scanning period.
[0046]
The Y driver 400 is supplied with VDDY as a positive power supply voltage and VSSY as a negative power supply voltage. The Y driver 400 applies a scanning signal of a positive power supply voltage VDDY (for example, 17 V) to the scanning line selected in the scanning period, and applies a scanning signal of a negative electric voltage VSSY (for example, 0 V) to the other scanning lines. It is supposed to be.
[0047]
When the liquid crystal panel 100 is actually used, an image signal from an image processing circuit (not shown) is supplied to the video line 113. This image signal is supplied to the source line 114 via the switching transistor 122 turned on by the sampling signal, and is applied to the pixel electrode 118 via the TFT 116 turned on by the scanning signal.
[0048]
In the present embodiment, an inspection voltage generation circuit 126 that supplies an inspection voltage to the video line 113 at the time of leak inspection is provided. The inspection voltage generation circuit 126 is controlled by an inspection voltage control circuit 127 described later, and can apply at least two kinds of voltages to the video line 113.
[0049]
The inspection voltage control circuit 127 always supplies the X driver 500 with the H level transfer start pulse DX and also supplies the Y driver 400 with the H level transfer start pulse DY at the time of leak inspection. The inspection voltage control circuit 127 detects a first inspection mode for detecting a leakage failure between the gate and the source, a leakage failure of the additional capacitance, and a leakage failure between the gate line and the capacitance line, and particularly detects a leakage failure of the additional capacitance. A second inspection mode can be set. In the first inspection mode, the inspection voltage generation circuit 126 is controlled to supply a relatively low voltage to the video line 113, and in the second inspection mode. The inspection voltage generation circuit 126 is controlled so that a relatively high voltage is supplied to the video line 113.
[0050]
For example, the inspection voltage generation circuit 126 applies a voltage of 5V to the video line 113 in the first inspection mode, and applies a voltage of 12V to the video line 113 in the second inspection mode.
The video line ammeter 124 measures the amount of current flowing through the video line 113. The gate line ammeter 125 measures the amount of current flowing through the scanning line 112.
[0051]
Next, a leak inspection method according to the embodiment configured as described above will be described with reference to the flowchart of FIG.
[0052]
When the inspection is started, the inspection voltage control circuit 127 sets the first inspection mode in step S1 of FIG. That is, the transfer start pulse DY supplied to the Y driver 400 is always set to H level, and the transfer start pulse DX supplied to the X driver 500 is always set to H level. Then, the inspection voltage control circuit 127 controls the inspection voltage generation circuit 126 to apply, for example, 5 V, which is a relatively low voltage value, to the video line 113 (step S2).
[0053]
Since the transfer start pulse DY is always at the H level, the output from the Y driver 400 to all the scanning lines 112 becomes the voltage VDDY. For example, 17V is adopted as the voltage VDDY. Further, since the transfer start pulse DX is always at H level, the X driver 500 outputs H level signals as all the sampling signals S1 to Sn. As a result, the switching transistors 122 in all the columns are turned on, and the voltage applied to the video line 113 is also supplied to all the source lines 114. On the other hand, the signal NRG is set to L level, the transistor 123 is off, and the source line 114 is in a floating state.
[0054]
Therefore, in this state, all the source lines 114 are set to 5V, and all the scanning lines 112 are set to 17V. Then, the TFTs 116 of all the pixels are on. Next, a current value is detected in step S3. In the first inspection mode, 17V is applied to the gate of the TFT 116, 5V is applied to the source, and a potential difference of 12V is set between the gate and the source. The additional capacitor 119 is applied with a differential voltage between the common voltage VSSY (0 V) supplied to the capacitor line 120 and the drain voltage (approximately 5 V). The potential difference between the scanning line 112 and the capacitor line 120 is 17V-0V = 17V.
[0055]
It is assumed that no leak current is generated between the gate and source of the TFT 116 and between the additional capacitor 119 and the scanning line 112 and the capacitor line 120. In this case, no current flows through either the video line 113 or the scanning line 112. On the other hand, when a defect occurs in these inspection parts, a leak current flows due to a voltage applied to these inspection parts.
[0056]
That is, the leakage current between the gate and the source of the TFT 116 flows to the video line 113 through the source line 114 and also to the scanning line 112. Further, the leakage current generated in the additional capacitor 119 flows through the capacitor line 120 and also flows through the video line 113. Further, leakage current between the scanning line 112 and the capacitor line 120 flows to the scanning line 112.
[0057]
Therefore, a leak failure between the gate and the source can be detected by the video line ammeter 124 and the gate line ammeter 125. The leakage failure of the additional capacitor 119 can be detected by the video line ammeter 124. Further, a leak failure between the scanning line 112 and the capacitor line 120 can be detected by the gate line ammeter 125.
[0058]
In step S3, the current flowing through the video line 113 and the gate line 125 is measured by these ammeters 124 and 125. In step S4, good or bad is determined from the measurement results of the ammeters 124 and 125. For example, when a current value of a predetermined level or more is detected only by the gate line ammeter 125, it can be determined that a leakage failure between the scanning line 112 and the capacitor line 120 has occurred. Further, when a current value of a predetermined level or more is detected only by the video line ammeter 124, it can be determined that a leakage failure of the additional capacitor 119 has occurred. When a current value of a predetermined level or more is detected in both the gate line ammeter 125 and the video line ammeter 124, a leak failure between the gate and the source, a leak failure in the additional capacitor 119, the scanning line 112 and the capacitor line It can be determined that at least one of the leak failures between 120 and 120 has occurred.
[0059]
On the other hand, when both the video line ammeter 124 and the gate line ammeter 125 have a measured current value of 0, in the first inspection mode, a leak failure between the gate and the source, a leak failure in the additional capacitor 119, and a scan. It is determined that no leak failure has occurred between the line 112 and the capacitor line 120.
[0060]
However, in the first inspection mode, the applied voltage between the gate and the source is sufficiently high as 12V, and the applied voltage between the scanning line 112 and the capacitor line 120 is also sufficiently high as 17V. On the other hand, the terminal voltage of the additional capacitor 119 is relatively low at 5V. In actual use, considering that the average level of the image signal is about 12 V, the reliability of the inspection result for the additional capacitor 119 is relatively low.
[0061]
Therefore, in the present embodiment, in the next step S5, the inspection voltage control circuit 127 sets the second inspection mode. That is, the inspection voltage control circuit 127 controls the inspection voltage generation circuit 126 to supply a relatively high voltage, for example, 12 V to the video line 113 (step S6). That is, in this case, all the source lines 114 are set to 12V.
[0062]
Accordingly, in this second inspection mode, the applied voltage between the gate and the source is (17-12) V = 5V, the applied voltage between the scanning line 112 and the capacitor line 120 is also 12V, and the additional capacitor 119 The terminal voltage is 12V. In the next step S7, the current values of the gate line ammeter 125 and the video line ammeter 124 are measured, and in step S8, good or bad is determined. Also in this case, the same determination as in the first inspection mode is performed.
[0063]
In the second inspection mode, since the terminal voltage of the additional capacitor 119 is set to a relatively high voltage value similar to that during actual use, the reliability of the inspection result for the additional capacitor 119 is sufficiently high.
[0064]
In other words, a good defect is determined in the first inspection mode for a leak defect between the gate and the source, and a good defect is determined in the first and second inspection modes for a leak defect between the scanning line 112 and the capacitor line 120. As for the leakage failure of the additional capacitor 119, it is determined whether it is good or bad in the second inspection mode. The inspection voltage control circuit 127 presents to the inspector the good / bad determination result in the first inspection mode and the second inspection mode (step S9).
[0065]
As described above, in this embodiment, the gate-source leakage failure, the scanning line 112 and the capacitance are caused by the first inspection mode and the second inspection mode using two different voltages as inspection voltages. It is determined whether the leakage between the line 120 and the additional capacitor 119 is defective. In any inspection region, an inspection with a sufficient applied voltage is possible, and a highly reliable inspection result can be obtained.
[0066]
That is, in the first inspection mode, by applying a voltage that increases the difference from the voltage applied to the scanning line as much as possible to the video line, it is possible to reliably detect a leak failure between the gate and the source. In this inspection mode, by applying a voltage that increases the difference from the common potential of the capacitor line as much as possible to the video line, it is possible to reliably detect a leakage failure of the additional capacitor.
[0067]
In particular, since the insulating film of the capacitor line has become thinner in recent years, it is easy to cause a leakage failure of the additional capacitor, and this embodiment is extremely useful. In the above embodiment, the second inspection mode is performed after the first inspection mode. However, it is obvious that the first inspection mode may be performed after the second inspection mode is performed. It is.
[0068]
In the above embodiment, an example in which 17V is applied to the scanning line and 5V or 12V is applied to the video line has been described. However, the inspection voltage is not limited to this, and various voltages can be selected. For example, 2 V may be applied to the video line as a low voltage, and in this case, it becomes easier to detect a leak failure between the gate and the source.
[0069]
In the above embodiment, the liquid crystal panel has been described as an example of the inspection target. However, the switching elements arranged in an array are designated by the X address and the Y address, and between the switching element and a predetermined common potential. The present invention can be applied to various matrix substrates on which additional capacitors are formed.
[0070]
Further, the present invention can also be applied to a front-stage gate type liquid crystal panel in which an additional capacitor is formed between a drain and a previous-stage scan line by appropriately switching between a voltage applied to the scan line and a voltage applied to the video line.
[0071]
The present invention can also be applied to EL devices, electrophoresis devices, and the like.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram for explaining a leak inspection apparatus according to a first embodiment of the invention.
FIG. 2 is a perspective view showing a configuration of a liquid crystal panel 100 in FIG.
FIG. 3 is a cross-sectional view taken along line AA ′ of FIG.
FIG. 4 is a flowchart for explaining a leak inspection method according to the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 ... Liquid crystal panel, 112 ... Scan line, 113 ... Video line, 114 ... Source line, 116 ... TFT, 119 ... Additional capacity, 124 ... Video line ammeter, 125 ... Gate line ammeter, 126 ... Test voltage generation circuit, 127: Inspection voltage control circuit.

Claims (7)

A plurality of scanning lines and a plurality of source lines; a switching element provided corresponding to an intersection of the scanning lines and the source line; and an additional capacitor connected between the switching element and a predetermined common potential. A first voltage application process for applying an inspection scanning voltage for inspection to the scanning lines of the matrix substrate;
A second voltage application process of applying a first voltage, which is an inspection source voltage for inspection, to the source line;
A first current detection process for detecting a current flowing through the source line and a current flowing through the scanning line in the first inspection mode by the first and second voltage application processes;
A third voltage application process for applying a second voltage different from the first voltage, which is an inspection source voltage for inspection, to the source line;
A second current detection process for detecting a current flowing through the source line and a current flowing through the scanning line in the second inspection mode by the first and third voltage application processes;
And a determination process for determining a leakage failure of the switching element and a leakage failure of the additional capacitor by the first and second current detection processes. The first voltage is the inspection source voltage for detecting a leakage failure of the switching element,
The second voltage is the inspection source voltage for detecting a leakage failure of the additional capacitor,
The difference between the first voltage and the scanning voltage for inspection is larger than the second voltage, and the difference between the second voltage and the common potential is larger than the first voltage. The leak inspection method according to claim 1 . The switching element is a transistor formed on the matrix substrate by a semiconductor process,
2. The determination process according to claim 1, wherein a leakage failure between the gate and the source of the transistor and a leakage failure of the additional capacitor connected between the drain of the transistor and the predetermined common potential are determined. The leak inspection method described in 1. The plurality of source lines are connected to video lines to which image signals are supplied,
2. The leak inspection method according to claim 1, wherein the first and second current detection processes detect a current flowing through the source line by detecting a current flowing through the video line. 3.   5. The third voltage applying process sets a voltage value based on a level of an image signal supplied to the video line as the second voltage that is the inspection source voltage. The described leak inspection method. A plurality of scanning lines and a plurality of source lines; a switching element provided corresponding to an intersection of the scanning lines and the source line; and an additional capacitor connected between the switching element and a predetermined common potential. First current detection means for detecting a current flowing in the source line of the matrix substrate;
Second current detection means for detecting a current flowing in the scanning line;
First voltage applying means for applying an inspection scanning voltage for inspection to the scanning line;
Second voltage applying means for applying an inspection source voltage for inspection to the source line;
While switching the source voltage for inspection by the second voltage applying means, switching between two or more types, it is determined whether the switching element leaks or the additional capacitor leaks according to the detection results of the first and second current detecting means. A leak inspection apparatus comprising: an inspection control means for performing the inspection. The inspection control means generates a first voltage as the inspection source voltage for detecting a leakage failure of the switching element, and a second voltage as the inspection source voltage for detecting a leakage failure of the additional capacitor. Generate a voltage of
The difference between the first voltage and the scanning voltage for inspection is larger than the second voltage, and the difference between the second voltage and the common potential is larger than the first voltage. The leak inspection apparatus according to claim 6.

Images