JPH11174397A - Device and method for inspecting liquid crystal driving substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the inspection precision by calculating an inspection threshold value from image voltages of respective pixel electrodes. SOLUTION: The inspecting device for a liquid crystal driving substrate A provided with many pixel electrodes a2 in matrix consists of an electrooptic element plate which is composed of a liquid crystal sealed in a flat plate shape and a transparent electrode 1b provided on one surface of the liquid crystal and arranged opposite the liquid crystal driving substrate so that the liquid crystal is by the transparent electrode, a power unit 10 which applies specific voltages to the pixel electrodes and transparent electrode respectively, an image pickup means 7 which photographs an image of the top surface of the electrooptic element plate and outputs an image signal corresponding to its luminance, and an image processor 8 which compares image voltages of the respective pixel electrodes obtained from the image signal with the specific threshold value to detect a defective pixel electrode that is not applied with the voltage normally and outputs the detection result as the inspection result of the liquid crystal driving substrate. Consequently, the image processor calculates the inspection threshold value from the image voltages of the respective pixel electrodes a2 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for inspecting a liquid crystal driving substrate, and more particularly, to inspecting an operation state of a liquid crystal driving substrate based on a surface image of an electro-optical element arranged opposite to the liquid crystal driving substrate. It relates to the technology to be performed.

[0002]

2. Description of the Related Art As is well known, a liquid crystal display panel has a liquid crystal driving substrate for applying an electric field to the liquid crystal oppositely disposed on a glass plate in which the liquid crystal is sealed. This liquid crystal display panel controls a data voltage applied to a pixel electrode of a liquid crystal driving substrate to adjust an electric field applied to the liquid crystal, and controls an optical transmittance of the liquid crystal by adjusting the electric field to display an image. A liquid crystal driving substrate used in such a liquid crystal display panel includes a plurality of pixel electrodes provided in a matrix on a glass plate, and controls a voltage written to the pixel electrodes using a switching element such as a TFT. It is.

FIG. 8 is a plan view showing a configuration example of an active matrix type liquid crystal driving substrate A using a TFT (thin film transistor) as one kind of such a liquid crystal driving substrate. In this figure, a large number of pixel electrodes a2 and TFTs a3 are formed on the surface of a glass substrate a1 at regular intervals in a matrix. That is, the pixel electrodes a2 and the TFTs a3 are arranged in a matrix at regular intervals in the horizontal and vertical directions of the image displayed by the liquid crystal drive substrate A.

[0004] A plurality of gate lines a4 parallel to each other are arranged between the pixel electrode a2 and the TFT a3 at a predetermined pitch interval.
The data wiring a5 is laid at predetermined pitch intervals so as to be orthogonal to. Each TFT a3 has a source terminal connected to the data line a5, a drain terminal connected to the pixel electrode a2, and a gate terminal connected to the gate line a4. Each of these TFTs a3 becomes conductive when a predetermined voltage is applied from the gate wiring a4 to each gate terminal, and at this time, a voltage applied to the source terminal via each data wiring a5 is supplied to each pixel electrode a2.

[0005] Such a liquid crystal driving substrate A is in the middle of a manufacturing process of a liquid crystal display panel, and in order to protect each TFT a3 from static electricity or the like, a gate wiring a4 is connected to a short bar a6, and a data wiring is provided. a5 is connected to each of the short bars a7. When the liquid crystal driving substrate A is completed as a liquid crystal display panel, each gate line a4 and data line a5 are connected to each short bar a,
a7 and is connected to the drive circuit.

As an inspection apparatus for inspecting the operation of the liquid crystal driving substrate A, there is an inspection apparatus using an electro-optical element plate (referred to as a modulator) described in, for example, JP-A-5-256794. FIG. 9 is a schematic diagram of a configuration example of an inspection device using such a modulator. In this figure, reference numeral B is a modulator. The modulator B has a thin film transparent electrode b2 attached to one surface of a liquid crystal sheet b1 in which liquid crystal is sealed, and a semiconductor reflective film b3 for reflecting light applied to the modulator B is deposited or attached to the other surface. It is configured together.

The modulator B is fixed to the inspection apparatus main body, and the glass substrate on which the plurality of liquid crystal driving substrates A are formed as described above is mounted on an XY stage (not shown) and For a small gap (10μ
m to 20 μm). A predetermined voltage necessary for inspecting the operation of the liquid crystal driving substrate A is applied to the thin film transparent electrode b2 of the modulator B and the gate electrode and the source electrode of each TFTa3 of the liquid crystal driving substrate A by the voltage applying device C. Further, the surface of the modulator B is irradiated with light by a halogen lamp D.

In this state, the CCD camera E captures a pattern on the surface of the modulator B as an image by the reflected light from the surface of the modulator B. At this time, XY
When the stage is operated, each liquid crystal driving substrate A on the glass substrate is sequentially opposed to the modulator B, and a surface image of the modulator B at this time is captured. When the size of the liquid crystal driving substrate A is large, the entire region of the liquid crystal driving substrate A may not be able to face the modulator B at the same time. In such a case, the liquid crystal driving substrate A is divided into several small areas,
By operating the XY stage, the small area is
, The surface image of the modulator B is photographed for the entire region of the liquid crystal driving substrate A.

Since the liquid crystal driving substrate A is arranged to face the modulator B at a small interval, the liquid crystal sheet b
The orientation of molecules of the liquid crystal sealed in 1 changes under the influence of the electric field generated between the thin film transparent electrode b2 and each pixel electrode a2 of the liquid crystal driving substrate A. As a result,
The light transmittance of the liquid crystal sheet b1 is adjusted according to the state of the molecular orientation of the liquid crystal, so that the reflectance of the light applied to the modulator B changes.

[0010] As a result, the surface image of the modulator B to be taken by the CCD camera E is an image brightness which reflects the voltage applied to each pixel electrode a2 of the liquid crystal driving substrate A (voltage image V _I). The image processing device F, by comparing the voltage image V _I with a predetermined inspection threshold binarized, the pixel electrode normal voltage based on the processing result of the binarization processing is not applied a2 (defective pixel) is specified, and the quality of the liquid crystal drive substrate A is inspected based on, for example, the number of defects. And this test result,
It is sent to the monitor G and displayed.

[0011] Here, the inspection threshold V _R is a function of the position x _i in the horizontal direction (X direction) of the predetermined fixed value and a liquid crystal driving substrate A for binarizing voltage image V _I It is given as _{(V R = a · x i} + b) or a function of the position y _i in the vertical direction _{(Y-direction) (V R = c · y} i + d).
Note that a, b, c, and d are constants.

[0012]

In the above-mentioned prior art, although the binarization process can be performed at high speed,
It is difficult to improve the inspection accuracy because it is vulnerable to disturbance as described below. Figure 10 is an illustration of an example of a relationship between the voltage image V _I and the inspection threshold V _R of portions of the liquid crystal driving board A, (a) ~ (d ) each of the first to fourth It corresponds to the part. As shown in this figure, the inclination of the liquid crystal driving substrate A with respect to the modulator B and the like (disturbance).
Due to the voltage image V _I is the fourth from the first portion
There may be a constant slope over the part.

In such a situation, the inspection threshold V
If a fixed value of _R, and the upper threshold V _RU and the upper limit threshold V _RL of the inspection threshold V _R, must be set to the interval wider in view of the slope of the voltage image V _I .
For this result, large defective pixel voltage image V _I differ not detected as a defect, also □ pixel electrode voltage image V _I around as indicated by the symbol relative to the surrounding of the pixel electrode as shown by ○ mark Therefore, there is an inconvenience that a pixel that does not need to be recognized as a defective pixel without much difference is determined as a defect. Therefore, when a fixed value inspection threshold V _R is difficult to improve the inspection accuracy.

Further, when setting an inspection threshold V _R by 1-dimensional function of the position x _i or position y _i as described above, for example, for one-dimensional gradient of the voltage image V _I By setting the slopes of the upper threshold value V _RU and the upper threshold value V _RL so as to be parallel, it is possible to improve the inspection accuracy as compared with the case where the inspection threshold value V _R is a fixed value. is there. However, the slope of the voltage image V _I, for example, a case that varies in two dimensions is the location x _i and the position y _i. For such a state, the position x _i or position y how to set the inspection threshold V _R by 1-dimensional function of _i is not valid, the pixel electrodes arranged over the X or Y direction It is difficult to accurately inspect all of a2.

The present invention has been made in view of the above-described problems, and has as its object to provide a liquid crystal driving board inspection apparatus and an inspection method capable of accurately inspecting a liquid crystal driving board. .

[0016]

In order to achieve the above object, the present invention provides a liquid crystal driving substrate inspection apparatus according to the first aspect.
As a means of, in a liquid crystal driving substrate inspection device in which a large number of pixel electrodes are provided in a matrix, a liquid crystal sealed in a plate shape and a transparent electrode provided on one surface of the liquid crystal, the liquid crystal is a transparent electrode An electro-optical element plate disposed opposite to the liquid crystal driving substrate so as to be sandwiched between them, a power supply device for applying a predetermined voltage to each of the pixel electrode and the transparent electrode, and an image of the surface of the electro-optical element plate. Imaging means for outputting an image signal corresponding to the luminance, and comparing the image voltage of each pixel electrode obtained from the image signal with a predetermined inspection threshold to detect a defective pixel electrode to which a voltage is not normally applied, An image processing device that outputs a detection result as an inspection result of the liquid crystal driving substrate. The image processing device employs a unit that calculates an inspection threshold from an image voltage of each pixel electrode. As the second means relating to the inspection apparatus for the liquid crystal drive substrate, the first means employs means for calculating the inspection threshold value based on a plurality of image voltages sampled from the image voltages of the respective pixel electrodes. May be. Further, as a third means relating to an inspection apparatus for a liquid crystal drive substrate, in the first or second means, a plurality of inspection thresholds are included within a predetermined range near an average value of image voltages of the respective pixel electrodes. Means to calculate the average value of the image voltages. The fourth related to the inspection device for the liquid crystal drive substrate
In the first or second means, means for calculating the inspection threshold value as a mode value of an image voltage obtained by forming a histogram of the image voltage of each pixel electrode is employed.

On the other hand, in the present invention, as a first means relating to a method of inspecting a liquid crystal driving substrate, a liquid crystal sealed in a plate shape and a liquid crystal of the liquid crystal are mounted on a liquid crystal driving substrate provided with a large number of pixel electrodes in a matrix. An electro-optical element plate composed of a transparent electrode provided on one surface is disposed so as to face the liquid crystal between the transparent electrodes, and a predetermined voltage is also applied to the pixel electrode and the transparent electrode. In a method of inspecting a liquid crystal driving substrate based on an image voltage of each pixel electrode obtained from a surface image of an element plate, a process of calculating an inspection threshold based on an image voltage of each pixel electrode, and inspecting the surface image. A means comprising a process of performing a binarization process by comparing with a threshold value and a process of detecting a pixel electrode to which a voltage is not normally applied as a defective pixel electrode based on a signal obtained by the binarization process is employed. Also, the second method relating to the inspection method of the liquid crystal driving substrate is described.
Means for sampling a plurality of image voltages from among the image voltages of the pixel electrodes and calculating an inspection threshold based on the plurality of image voltages in the first means relating to the inspection method. You may adopt it. As a third means relating to the liquid crystal drive substrate inspection method, in the first or second means relating to the inspection method, the inspection threshold value is calculated by calculating an average value of image voltages of the respective pixel electrodes. Means is adopted in which an image voltage within a predetermined range near the value is selected, and a limited average value is obtained by calculating from the selected image voltage. As a fourth means relating to the above-mentioned inspection method of the liquid crystal drive substrate, in the first or second means relating to the above-mentioned inspection method, the inspection threshold value is obtained by converting an image voltage of each pixel electrode into a histogram, Means that a value is set is adopted.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a liquid crystal driving substrate inspection apparatus according to an embodiment of the present invention; Note that the present embodiment relates to the inspection of the liquid crystal driving substrate A described above, and the same reference numerals are given to the members already described, and the description thereof will be omitted.

FIG. 1 is a functional configuration diagram of the inspection apparatus according to the present embodiment. In this figure, reference numeral 1 denotes an electro-optical element plate (modulator), which is composed of a liquid crystal sheet 1a in which liquid crystal is sealed in a flat plate shape, a thin film transparent electrode 1b, and a semiconductor reflection film 1c. The modulator 1 is configured by, for example, bonding a thin film transparent electrode 1b to one surface of a square (36 mm × 36 mm) liquid crystal sheet 1a, and depositing or bonding a semiconductor reflection film 1c to the other surface.

The modulator 1 is fixed to an inspection apparatus main body (not shown) so that its surface is horizontal and the semiconductor reflection film 1c faces downward.
The liquid crystal driving substrate A is arranged to be opposed to (10 μm to 20 μm).

Reference numeral 2 denotes an XY stage, which moves the liquid crystal driving substrate A in a horizontal plane under the control of a control device (not shown). For example, an XY stage 2 having an accuracy of ± 5 μm over the entire movable range is used. When the liquid crystal driving substrate A is relatively large, the area of the liquid crystal driving substrate A is larger than that of the modulator 1. In this case, since all the pixel electrodes a2 cannot face the modulator 1 at a time, X
By operating the -Y stage 2 to move the liquid crystal driving substrate A in a horizontal plane, all the pixel electrodes a2 of the liquid crystal driving substrate A are opposed to the modulator 1 for inspection.

Reference numeral 3 denotes a beam splitter, and 4 denotes a light source. The beam splitter 3 is provided above the modulator 1 in a facing state, reflects light emitted from a light source 4 provided on a side of the beam splitter 3, and irradiates the entire surface of the modulator 1. Further, the beam splitter 3 includes a modulator 1
It has the function of transmitting the reflected light from the upper side. Here, a light source that emits high-luminance light, such as a halogen lamp, is used as the light source 4, and its light emission is controlled in a strobe shape by a control device (not shown).

Reference numeral 5 denotes a filter (optical filter) which is provided above the beam splitter 3 and transmits only light in a specific wavelength range from the reflected light of the modulator 1 transmitted through the beam splitter 3 to the lens 6. It is. The lens 6 is a convex lens that collects light transmitted through the filter 5 and guides the light to the CCD camera 7.

The CCD camera 7 captures an image of the surface of the modulator 1 based on the light incident from the lens 6, that is, a voltage image that changes in accordance with the voltage applied to the pixel electrode a2. This CCD camera 7
For example, the frame frequency at the time of imaging is 30 Hz, the spatial resolution is 2.8 CCD / 100 μm, and the resolution is 1024 pixels ×
It comprises a CCD (Charge Coupled Device) of 1024 pixels, and outputs the picked-up voltage image to the image processing device 8 as digital image data. The pitch of the pixel electrodes a2 of the liquid crystal driving substrate A is, for example, about 100 μm, and the resolution of the CCD camera 7 is
It has sufficient performance for pitch 2.

The image processing device 8 comprises an image processing board and an operation unit (a kind of computer) for processing the image processing result by the image processing board based on an image processing program. By subjecting the digital image data input from the CCD camera 7 to predetermined digital image processing, a defective pixel (a pixel electrode a2 to which a data voltage is not normally applied) of the liquid crystal driving substrate A is detected from the voltage image. The result is output to the monitor 9. For example, the inspection result information displayed on the monitor 9 is an image indicating the distribution state of the defective part and the normal part by color, numerical information indicating the number of defective pixels, and the like.

Reference numeral 10 denotes a power supply device for applying a bias voltage to the thin-film transparent electrode 1b of the modulator 1 and for applying a gate voltage and a data voltage to the liquid crystal drive substrate A. The bias voltage is, for example, C
It is a bipolar square wave of ± 230 V _pp at 1/2 of the frame frequency of the CD camera 7 of 30 Hz, that is, at a frequency of 15 Hz. The power supply device 10 outputs the gate voltage, the data voltage, and the bias voltage under the control of a control device (not shown).

Next, an inspection method using the inspection apparatus configured as described above will be described with reference to FIGS.

First, the liquid crystal driving substrate A to be inspected will be described with reference to FIG. In this embodiment,
An aggregate substrate A ′ in which six liquid crystal driving substrates A1 to A4 configured similarly to the above-described liquid crystal driving substrate A are integrally formed on a rectangular glass substrate _AG is to be inspected. In A1 to A4, m pixel electrodes a2 in the horizontal direction and n pixel electrodes in the vertical direction (total m × n) are arranged in a matrix. Further, the glass substrate _AG is provided with two position correction marks M1 and M2 near a vertex located on one diagonal line. Each of the liquid crystal driving substrates A1 to A4 is
It is formed on the glass substrate _AG so as to have a fixed positional relationship with the position correcting marks M1 and M2.

When inspecting the collective substrate A 'thus formed, the inspection proceeds according to the flowchart shown in FIG. First, in a state where the XY stage 2 has been moved to the reference position, the collective substrate A ′ is placed on the XY stage 2. In this case, the collective substrate A ′ is XY
It is positioned at a predetermined position on the XY stage 2 by being fixed by a banking pin or the like provided on the stage 2 (step S1). In this state, the collective substrate A ′ is fixed on the XY stage 2 in a horizontal state.

When the collective substrate A 'is positioned on the XY stage 2 as described above, the CCD camera 7 is moved to a predetermined position on the collective substrate A' and the position correcting marks M1,
M2 is photographed. The image captured by this photographing is input to the image processing device 8, and the positions of the position correction marks M1 and M2 in the image are detected. Then, the image processing device 8 calculates a deviation from the standard position of the position correction marks M1 and M2 given in advance by teaching, and sets the position of the collective substrate A ′ in the horizontal plane so that the deviation becomes “zero”. Is corrected by

More precisely, the above-mentioned inspection apparatus has C
There is provided a position detection camera whose optical positional relationship with the CD camera 7 is uniquely defined. The positions of the position correction marks M1 and M2 are photographed by the position detection camera, and the position of the collective substrate A 'is set in the horizontal plane so that the deviation of the position correction marks M1 and M2 from the standard position is "zero". Is to be corrected.

When the relative positional relationship between the CCD camera 7 and the collective substrate A 'on the XY stage 2 is defined in this way, the modulator B is located between the CCD camera 7 and the collective substrate A'. The XY stage 2 is operated while the CCD camera 7 is lowered and the XY stage 2 is operated.
1 is opposed to the modulator B (step S
3). Here, the XY stage 2 has the size of the pixel electrode a2 and each CC constituting the CCD camera 7 as described above.
Since it has a sufficient accuracy (± 5 μm) for the pixel size of D, each pixel electrode a2 on the liquid crystal driving substrate A1 and CC
The positional relationship with the D camera 7 is maintained within a certain error range.

Therefore, the positional relationship between the CCD camera 7 and the collective substrate A 'is defined within a certain error range by the processing up to the step S3. For example, as shown in FIG. And the position of each pixel electrode a2 can be regarded as having a certain relationship.

Subsequently, the power supply 10 is operated to write a predetermined voltage to all the pixel electrodes a2 of the liquid crystal driving substrate A1, and the voltage image (n) of all the pixel electrodes a2 at this time is written.
× m voltage images) are photographed by the CCD camera 7 (step S4). On the other hand, the digital image signal of the voltage image of the liquid crystal drive substrate A1 output from the CCD camera 7 is composed of a voltage data group in which the output voltage of each CCD of the CCD camera 7 is a digital value.

In step S5, the image voltage of each pixel electrode a2 is calculated based on the output voltage of the CCD. That is, the image processing device 8 temporarily stores this voltage data group in the memory in association with the address of each CCD,
Further, based on the arrangement pitch of the CCD and the arrangement pitch of the pixel electrodes a2 previously stored as inspection data in the image processing device 8, and the positional relationship between the CCD camera 7 and the collective substrate A ', each pixel electrode corresponding to the CCD is determined. The center position (X, Y) of a2 is calculated. Then, the calculation result is stored in the image processing device 8 as a table corresponding to each pixel electrode a2.

Here, referring to FIG. 4, each pixel electrode a2
The calculation processing of the center position pa (X, Y) will be described. For example, the center position X of the pixel electrode a2 in the horizontal direction (X direction) is the arrangement pitch of the CCDs c1 to c12 in the X direction, the arrangement pitch of the pixel electrodes a2 in the X direction, and the positional relationship between the CCD camera 7 and the collective substrate A '. based on CCDc1~c12 the positional relationship of the pixel electrode a2 based on, is calculated as CCD number in which the left edge p _0x leftmost CCDc1 the reference (0). In the case of this figure, the center position X in the X direction of the pixel electrode a2
Becomes “1.5”. The center position Y in the Y direction of the pixel electrodes a2, relative to the upper edge p _0y of CCDc1 CC
It is calculated as D number.

When the center position pa (X, Y) of each pixel electrode a2 is calculated as a positional relationship with each of the CCDs c1 to c12 in this manner, (n.times.m) pixels are obtained based on the result. image voltage V _i1 electrode a2 are calculated. That is, since the pixel electrode a2 is entirely or partially opposed to the CCDs c1 to c12, the center position pa
(X, Y) by a weighted average of the output voltage of each CCDc1~c12 based on the image voltage V _i1 of each pixel electrode a2 is calculated.

For example, in order to facilitate understanding, in the case of FIG. 4, the center position X of the pixel electrode a2 in the X direction is "1.5", and the center position Y of the pixel electrode a2 in the Y direction is "2. 0 ". Therefore, CCDs c4 and c7 are C
Cdc6, c9 same area (half of the total counter) it means to face the only pixel electrodes a2, when the output voltage of each CCDc1~c12 and Vc1～Vc12, the image voltage V _ia the pixel electrode a2 following formula ( It is calculated based on 1). _{V ia = (k1 · Vc1 +} k2 · Vc2 + k3 · Vc3 + k4 · Vc4 + k5 · Vc5 + k6 · Vc6 + k7 · Vc7 + k8 · Vc8 + k9 · Vc9 k10 · Vc10 + k11 · Vc11 + k12 · Vc12) / 12 (1) where, k1 = 0.25 (i.e. 1/2 × 1/2), k2 = 0.
5 (ie, 1/2), k3 = 0.25, k4 = 0.5, k5
= 1.0, k6 = 0.5, k7 = 0.5, k8 = 1.0,
k9 = 0.5, k10 = 0.25, k11 = 0.5, k12 =
0.25

The processing in steps S6 and S7 is performed by an image processing board, that is, hardware provided in the image processing apparatus 8 because high-speed processing is required.

[0040] Subsequently, by the processing of steps S6 to S8, calculation processing of the inspection threshold based on the (n × m) pieces of image voltage V _i1 is performed as follows. Note that the following processing is performed as software by a kind of computer provided in the image processing apparatus 8.

First, the average value x ₁ and the standard deviation σ ₁ are calculated based on the (n × m) image voltages Vi ₁ (step S 6), and further included in the range of (x ₁ ± 2σ ₁ ). Is selected and extracted as a limited voltage image, and a limited average value x _1s based on the limited voltage image is selected.
Is calculated (step S7). Then, based on the limit average value x _1a, as shown in FIG. 5 (a), lower the inspection threshold V _L1 and the upper test threshold V _U1 to the liquid crystal driving substrate A1 is set. For example, a lower test threshold V _L1 and the upper limit test threshold V _U1 is set by subtracting a predetermined voltage value from the limiting average x _1a.

Here, the limited average value x _1a obtained by limiting only to the image voltage included in the range of (x ₁ ± 2σ ₁ ).
Is a graph in which the influence of a defective pixel whose image voltage has an extremely different value from other normal pixel electrodes is eliminated. In step S10, the image voltage of each pixel electrode a2 is binarized using the lower inspection threshold _VL1 and the upper inspection threshold _VU1 as the inspection threshold, and the pixels having the image voltages that deviate from the inspection threshold are binarized. The electrode a2 is detected as a defective pixel (Step S9). For example, the image voltage V _i1 in FIG.
In the above, since the image voltage of the portion marked with a circle deviates from the inspection threshold, it is determined that the pixel is defective.

When a defective pixel is detected as described above, the type of the defect is classified into several types according to its distribution (step S10). FIG. 6 is a diagram illustrating an example of the distribution of defective pixels. A pixel defect has several characteristic distributions depending on the cause. For example, in this figure, D1 and D2 are referred to as line defects, and D3 is referred to as a point defect. The line defect D1 is a defect that is continuous in the vertical direction of the liquid crystal driving substrate A1, and is generated when the above-described data wiring is cut by any one. The line defect D2 is a defect that is continuous in the horizontal direction of the liquid crystal driving substrate A1, and occurs when the gate wiring is cut at any point. Further, the point defect D3 is detected by any of the pixel electrodes a2.
This occurs when the TFT accompanying the device has a malfunction.

When the detection of defective pixels on the liquid crystal driving substrate A1 is completed, the image processing device 8 determines the continuous state of the defective pixels and the direction in which the defective pixels continue (horizontal direction or vertical direction).
Is determined, the type of the pixel defect is classified into a point defect, a line defect, and the like (step S10), and the result is output as the inspection result of the liquid crystal driving substrate A1 (step S11). Then, it is determined whether or not the inspection has been completed for all the liquid crystal driving substrates A1 to A4 for the collective substrate A '(step S12). The image processing device 8 previously stores, as inspection data, the configuration data of the collective board A ′ to be inspected, that is, the configuration data composed of the four liquid crystal drive boards A1 to A4. The judgment here is "N
o ", and the process returns to step S4.

Then, in step S4, the XY stage
2 is operated, the liquid crystal driving substrate A2 is
And is placed in an opposed state to the radiator B as described above.
Surface image of modulator B relates to liquid crystal drive substrate A2
It is photographed as a voltage image.
Image voltage V based on image_i2(See FIG. 5 (b)
Is calculated, and the inspection threshold is calculated in steps S6 to S8.
The value is the lower inspection threshold V _L2And upper limit inspection threshold V
_U2(See FIG. 5 (b)).
A defective pixel is detected based on the threshold (step S
9). Then, the defective pixel is classified (step S1).
0), the inspection result relating to the liquid crystal driving substrate A2 is output
(Step S11), inspection of all liquid crystal drive substrates A1 to A4
Termination is determined (step S12).

That is, by executing a loop process from steps S4 to S12, as shown in FIGS. 5A to 5D, each of the liquid crystal driving substrates A1 to A4 is set for all the liquid crystal driving substrates A1 to A4. The inspection threshold is set to each image voltage V _i1
Is calculated as the lower limit test threshold V _L1 ~V _L4 and upper test threshold V _U1 ~V _U4 based on ~V _i4. Defective pixels of each of the liquid crystal drive substrates A1 to A4 are detected based on these inspection thresholds, respectively, and classification is performed.

Thus, all the liquid crystal driving substrates A1 to A1
When the inspection of A4 is completed, the determination in step S12 is “Ye
s ", classification information of defective pixels, the number of pixel defects, and the like are output to the monitor 9 as inspection results for each of the liquid crystal driving substrates A1 to A4 (step S13). In addition, based on the inspection result, the pass / fail of the liquid crystal drive substrates A1 to A4 is determined and output to the monitor 9. Further, for example, when three of the four liquid crystal driving substrates A1 to A4 are determined to be defective,
The pass / fail judgment of the collective board A ′ is “NG”, and the inspection ends.

Next, another embodiment of the present invention will be described. Note that the configuration of this embodiment is exactly the same as the above embodiment, and only the method of calculating the inspection threshold value is different. Therefore, in the following description, only the calculation method of the inspection threshold, which is a feature of the present embodiment, will be described.

In the present embodiment, the image processing device 8
The above (n × m) image voltages V _i1Into a histogram
I do. In this case, the image voltage V_i1Standard deviation σ from₁But
Calculated, and the step size of the histogram is, for example, 0.04σ₁
Is set to And the image with the largest number of data n
The voltage is used as the reference value of the inspection threshold, and is constant from the reference value.
By adding and subtracting the voltage value of
_L1And upper limit inspection threshold V_U1Is calculated as the inspection threshold
Is done. Note that this image voltage V_i1Histogram
Processing is performed by hardware using an image processing board for high-speed processing.
This is performed as wear processing.

As described above, in the present embodiment, the defective pixel is determined based on the inspection threshold value calculated for each of the liquid crystal driving substrates A1 to A4. The liquid crystal driving substrates A1 to A4 can be inspected with higher accuracy than in the case of inspecting the collective substrate A 'including A1 to A4.

In each of the above embodiments, the collective substrate A '
The inspection threshold is set for each of the liquid crystal driving substrates A1 to A4 for forming the above, but the present invention is not limited to this. For example, there is a case where one liquid crystal driving substrate is large and all the pixel electrodes cannot face the modulator at one time. In such a case, as shown in FIG. 7, it is possible to determine a pixel defect by setting an inspection threshold value for each voltage image obtained as a surface image of the modulator, that is, for each part of one liquid crystal driving substrate. Conceivable.

In the above embodiment, the inspection threshold value is calculated based on all the pixel electrodes a2 calculated for each of the liquid crystal driving substrates A1 to A4, that is, (n × m) image voltages. The calculation is performed by software processing based on the inspection program. Therefore, in order to reduce the processing time for calculating the inspection threshold, some of the (n × m) image voltages are sampled, and the image voltages ((n × m)) selected by the sampling are sampled. It is conceivable to calculate the inspection threshold based on the number of image voltages less than the number.

[0053]

As described above, according to the inspection apparatus and the inspection method for a liquid crystal driving substrate according to the present invention, the following effects can be obtained. (1) In an inspection apparatus for a liquid crystal driving substrate in which a large number of pixel electrodes are provided in a matrix, a liquid crystal sealed in a flat plate shape and a transparent electrode provided on one surface of the liquid crystal are used. An electro-optical element plate disposed opposite to the liquid crystal driving substrate so as to be sandwiched between them; a power supply device for applying a predetermined voltage to each of the pixel electrode and the transparent electrode; Imaging means for outputting an image signal corresponding to the luminance; comparing the image voltage of each pixel electrode obtained from the image signal with a predetermined inspection threshold to detect a defective pixel electrode to which a voltage is not normally applied; And an image processing device that outputs a result as an inspection result of the liquid crystal driving substrate. The image processing device calculates an inspection threshold from an image voltage of each pixel electrode. Typically As compared with the case of setting the 査 threshold, flexible it is possible to inspect the liquid crystal driving substrate, thus it can be conventionally improve inspection accuracy. (2) Since the inspection threshold is calculated based on a plurality of image voltages sampled from the image voltage of each pixel electrode, the calculation time for calculating the inspection threshold is reduced, and the inspection threshold is increased at a high speed. Can be calculated. Therefore, it is possible to reduce the time required for the inspection of the liquid crystal driving substrate.

[Brief description of the drawings]

FIG. 1 is a plan view showing an outline of a configuration of an inspection apparatus for a liquid crystal drive substrate in an embodiment of the present invention.

FIG. 2 is a plan view showing a configuration example of a collective board to be inspected in an embodiment of the present invention.

FIG. 3 is a flowchart illustrating a procedure of an inspection process according to the embodiment of the present invention;

FIG. 4 shows an embodiment of the invention according to the present application.
FIG. 3 is a plan view showing a positional relationship between a CCD of a CD camera and pixel electrodes.

FIG. 5 is an explanatory diagram showing a relationship between an image voltage of each liquid crystal driving substrate and an inspection threshold value in one embodiment of the present invention.

FIG. 6 is a plan view illustrating classification of pixel defects in an embodiment of the present invention.

FIG. 7 is a flowchart illustrating a procedure of another inspection process according to the embodiment of the present invention;

FIG. 8 is a plan view illustrating an example of a configuration of a liquid crystal driving substrate.

FIG. 9 is a schematic diagram showing a configuration example of a conventional liquid crystal drive board inspection apparatus.

FIG. 10 is an explanatory diagram illustrating an inspection threshold value in an inspection of a conventional liquid crystal driving substrate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Modulator 1a ... Liquid crystal sheet 1b ... Thin film transparent electrode (transparent electrode) 1c ... Semiconductor reflection film 2 ... XY stage 3 ... Beam splitter 4 ... Light source 5 ... Filter 6 ... Lens 7 ... CCD camera (imaging means) 8 ... Image processing device 9 ... Monitor 10 ... Power supply device A, A1 to A4 ... Liquid crystal drive substrate A '... Assembly substrate a1, _{AG G} ... Glass plate a2 ... Pixel electrode a3 TFT (thin film transistor) a4 Gate wiring a5 Data wiring a6, a7 Short bar D1, D2 Line defect D3 Point defect M1, M2 Position correction mark

Claims (8)

[Claims] An inspection apparatus for a liquid crystal driving substrate provided with a large number of pixel electrodes arranged in rows and columns, comprising: a liquid crystal sealed in a plate shape; and a transparent electrode provided on one surface of the liquid crystal. An electro-optical element plate disposed opposite to the liquid crystal driving substrate so as to be sandwiched between the electro-optical element plate and a transparent electrode; a power supply device for applying a predetermined voltage to each of the pixel electrode and the transparent electrode; Imaging means for taking an image of the image and outputting an image signal corresponding to the luminance of the image signal; comparing the image voltage of each pixel electrode obtained from the image signal with a predetermined inspection threshold value to detect a defect that the voltage is not normally applied; An image processing device that detects a pixel electrode and outputs the detection result as an inspection result of the liquid crystal driving substrate, wherein the image processing device calculates an inspection threshold from an image voltage of each pixel electrode. LCD drive Inspection apparatus of the plate. 2. The liquid crystal driving substrate inspection apparatus according to claim 1, wherein the inspection threshold value is calculated based on a plurality of image voltages sampled from the image voltages of the respective pixel electrodes. 3. The inspection threshold value is calculated as an average value of a plurality of image voltages included in a predetermined range near the average value of the image voltages of the respective pixel electrodes. An inspection device for a liquid crystal drive substrate as described in the above. 4. The inspection threshold value is calculated as a mode value of an image voltage obtained by converting an image voltage of each pixel electrode into a histogram.
An inspection device for a liquid crystal drive substrate as described in the above. 5. An electro-optical element plate comprising a liquid crystal sealed in a flat plate shape and a transparent electrode provided on one surface of the liquid crystal is formed on a liquid crystal driving substrate provided with a large number of pixel electrodes in a matrix. A predetermined voltage is also applied to the pixel electrode and the transparent electrode so as to be sandwiched between the electrodes, and a predetermined voltage is also applied to the pixel electrode and the transparent electrode. At this time, the liquid crystal is determined based on the image voltage of each pixel electrode obtained from the surface image of the electro-optical element plate. A method of inspecting a driving substrate, comprising: calculating an inspection threshold based on an image voltage of each pixel electrode; and performing a binarization process by comparing the surface image with the inspection threshold. Detecting a pixel electrode to which a voltage is not normally applied as a defective pixel electrode based on a signal obtained by the binarization process, the method comprising: 6. The liquid crystal driving substrate according to claim 5, wherein a plurality of image voltages are sampled from among the image voltages of each pixel electrode, and an inspection threshold value is calculated based on the plurality of image voltages. Inspection method. 7. An inspection threshold value is calculated by calculating an average value of image voltages of pixel electrodes, selecting an image voltage within a predetermined range near the average value, and calculating a limited average value from the selected image voltage. 6. The method according to claim 5, wherein the value is obtained by calculation.
Or the inspection method of a liquid crystal drive substrate according to 6. 8. The inspection method for a liquid crystal driving substrate according to claim 5, wherein the inspection threshold value is a histogram of an image voltage of each pixel electrode, and a mode of the histogram is set.