JPH05303068A - Device and method for inspecting display substrate - Google Patents

Abstract

PURPOSE:To provide the inspection device and its method which can detect surely and quickly a defective part before a display substrate is assembled on a liquid crystal display panel. CONSTITUTION:The device is constituted by providing an inspecting element 4 which is arranged opposingly in the upper part of a display substrate A, and whose optical quality is varied, when an electric field is applied, a light source 1 for irradiating the inspecting element 4 with light, a photodetector 2 for catching the light which irradiates the inspecting element 4 and is emitted from the inspecting element 4, a power source 10 for applying a voltage to between a picture element electrode 9 and the inspecting element 4 on the display substrate A, and a measuring means for measuring a variation of the light caught by the photodetector 2. In such a way, before assembling a liquid crystal panel, the number of defects and the kind of the detect can be grasped easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection device for inspecting defects occurring in a display substrate used for a liquid crystal display panel or the like, and an inspection method using the inspection device.

[0002]

2. Description of the Related Art In order to increase the screen size and density of a liquid crystal display panel suitable for liquid crystal display, a pixel electrode provided for each pixel arranged in rows and columns and a pixel electrode common to each pixel electrode are commonly used. An active matrix type using a display substrate provided with the provided gate wirings, source wirings and thin film transistors is advantageous, and at present, relatively small ones are being put to practical use.
Usually, in this type of liquid crystal display panel, after the display substrate is manufactured, a transparent substrate or the like is arranged on the display substrate via a spacer, and the liquid crystal is placed in a gap formed between the display substrate and the transparent substrate. A liquid crystal display panel is manufactured by encapsulating.

Under such a background, most of liquid crystal televisions currently produced have a pixel number of 250,000 to 500,000, and some have a pixel number of 1 million or more. ing.

[0004]

By the way, in order to form a large number of pixels and a large number of wirings corresponding thereto on a substrate, various film forming processes are carried out in a clean room in which dust is adjusted to be extremely small. However, when the pixel and wiring widths become extremely small, the presence of a small amount of microdust contained in the manufacturing atmosphere directly leads to disconnection defects and short circuit defects in pixel electrodes and wiring. Like These defects are currently used in the display substrate up to several to ten, but the present situation is that if the number of defects is more than that, the product is defective.

However, with the current manufacturing technology, it is extremely difficult to reduce the number of defects below the allowable limit. Therefore, in a liquid crystal display panel having a large number of pixels, the defective rate is extremely high, This causes the high price of large liquid crystal display panels. Furthermore, in the past,
When manufacturing a liquid crystal display panel using a display substrate, the inspection is not performed in the production line of the display substrate, the next manufacturing process is performed, and the liquid crystal display panel after the manufacturing is completed is energized to visually check each pixel. Has been investigated to see if it actually works, and defective products are discarded, which is a major cause of the very poor yield of liquid crystal display panels.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to surely and quickly find a defective portion of a display substrate before it is assembled into a liquid crystal display panel. It is an object of the present invention to provide an inspection device and a method therefor capable of easily grasping.

[0007]

According to a first aspect of the present invention, there is provided a display board inspection apparatus, which is configured to solve the above-mentioned problems.
In an apparatus for inspecting a display substrate having a plurality of pixel electrodes formed on a substrate, an inspection element, which is arranged facing the upper portion of the display substrate and whose optical properties change when an electric field is applied, and light is emitted to the inspection element. A light source for irradiating, a light receiver for irradiating the inspection element to capture light emitted from the inspection element, a power supply for applying a voltage between the pixel electrode on the display substrate and the inspection element, and It is characterized in that it comprises a measuring means for measuring a change in the light captured by the light receiver.

According to a second aspect of the present invention, there is provided a display substrate inspecting apparatus, wherein the inspecting element according to the first aspect is a polymer-dispersed liquid crystal in order to solve the above problems.

In order to solve the above-mentioned problems, the display substrate inspection apparatus according to a third aspect of the present invention is an apparatus for inspecting a display substrate having a plurality of pixel electrodes formed on the substrate. An inspection element composed of an electroluminescent element whose properties change, a light receiver for capturing light emitted from the inspection element, and a power supply for applying a voltage between the pixel electrode on the display substrate and the inspection element. And a measuring means for measuring a change in the light captured by the light receiver.

According to a fourth aspect of the present invention, there is provided a display substrate inspecting method, wherein, in order to solve the above problems, an electric field is applied in the display substrate inspecting method including a plurality of pixel electrodes formed on the substrate. An inspection element whose optical property is changed is disposed on the upper part of the display substrate, a voltage is applied between the pixel electrode of the display substrate and the inspection element, an electric field is applied to the inspection element, and the inspection element optical It is characterized in that the quality of the pixel electrode on the display substrate is detected by detecting a partial change in the physical property.

According to a fifth aspect of the present invention, there is provided a display substrate inspecting method, wherein the inspecting element according to the fourth aspect is a polymer dispersed liquid crystal.

According to a sixth aspect of the present invention, there is provided a method for inspecting a display substrate, wherein the inspection element according to the fourth aspect is an electroluminescence element in order to solve the above problems.

[0013]

The function of the inspection element is changed when an electric field is applied. Therefore, when this inspection element is placed on the display substrate and electricity is applied between the pixel electrode on the display substrate and the thin film transparent electrode on the inspection element, the optical property of the inspection element is changed by the electric field generated by each pixel electrode. ..

Therefore, if a disconnection occurs in the pixel electrode or other portion on the display substrate, a part of the pixel electrode does not operate even when power is supplied, and the inspection element on the pixel electrode that does not operate is optically changed. Does not occur. Further, when there is a short-circuit defect, an abnormal phenomenon that does not occur in a normal pixel electrode occurs such that an inspection element corresponding to a pixel electrode that should not originally operate operates. Therefore, by detecting the optical change of the inspection element by the light receiver in this way, the defects of the display substrate can be found collectively and quickly.

Here, in particular, when a polymer dispersed liquid crystal is used as the inspection element, the polymer dispersed liquid crystal is
For example, PDLC (Polymer Dispersed)
A nematic liquid crystal called LC) is dispersed in polymers having different refractive indices to have a transmission-scattering effect. When an electric field is applied, liquid crystal molecules are aligned and in a transmissive state.
In other words, there is a region where the amount of transmitted light changes linearly when the voltage is changed, and by utilizing this linearity, it is possible to easily capture the change in voltage as the change in the amount of transmitted light. Further, by irradiating the polymer-dispersed liquid crystal with light, the reflected light or transmitted light is captured by a light receiver, and the change amount of the reflected light or transmitted light is converted into an equivalent voltage, thereby The defect can be recognized as a change in the equivalent voltage.

Therefore, the above-mentioned properties of the polymer-dispersed liquid crystal are suitable for inspection of a display substrate having fine wiring and pixel electrodes.

Further, when an electroluminescence element (hereinafter referred to as an EL element) is used as the inspection element, the EL element usually has a voltage of 50 to 200 V between both electrodes and several H.
By applying an alternating voltage of several kHz from z, EL
The active species ions in the light emitting layer are excited to emit light. The basic operation principle of this EL element is that when a high electric field of about 10 ⁴ to 10 ⁶ V / cm is applied to the phosphor material, the electrons in the material are accelerated, and this is the luminescence center present in the phosphor. It is understood that EL is the luminescence that occurs when the excited luminescence center returns to the ground state by collision-exciting. Therefore, the defect of the pixel electrode of the display substrate can be grasped by utilizing this light emission.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A display substrate inspection apparatus of this embodiment will be described in detail below with reference to the drawings. (Embodiment 1) FIG. 1 shows a schematic structure of a main part of an inspection apparatus according to Embodiment 1. The light source 1 and a light receiving device for receiving reflected light from an inspection element on which detection light is incident are received. It is equipped with a device 2 and an image processing computer 3 connected to the light receiver 2, and a display substrate A can be arranged on the opposite surface of the inspection element 4.

In the figure, reference numeral 10 is a voltage application device for applying a voltage between the thin film transparent electrode 5 on the upper surface of the inspection element 4 and the display substrate A, which is provided with a switch and a power supply section. As shown in FIG. 1, a voltage can be applied from the gate wiring 16 and the source wiring 15 to the thin film transparent electrode 5 on the upper surface of the inspection element 4 and all the pixel electrodes 9 on the display substrate A. The voltage applying device 10
The pulse voltage can be applied to the source wiring 15 and the gate wiring 16 separately, and the pulse voltage, pulse width, and cycle can be changed.

The display substrate A to be inspected in the first embodiment is a known one used for a liquid crystal display panel. For example, as shown in FIG. 9, a large number of source wirings 15 for flowing data signals, A large number of gate wirings 16 for flowing a scanning signal are formed in alignment with each other on a substrate, pixel electrodes 9 are formed between them, and each pixel electrode 9 is connected via a switching element (thin film transistor) 17 to a source wiring. 1
5 is connected to the gate wiring 16, each source wiring is connected to the signal supply circuit 12, and each gate wiring 16 is connected to the scanning circuit 13.

Although various structures are known for the wiring structure of the display substrate, the structure of the pixel electrode 9 and the structure of the switching element 17, any type of structure is suitable for the inspection apparatus of the present invention. Can be applied,
The structure of the display substrate A is not particularly limited.

The inspection element 4 is made of polymer-dispersed liquid crystal whose optical properties change when an electric field is applied to it. As shown in FIG. 2, the polymer dispersed liquid crystal has a light reflection plate 7 such as an Al vapor deposition film formed on the upper surface of a liquid crystal sheet 6, and a thin film transparent electrode 5 attached on the upper surface of the liquid crystal sheet 6. It is a sheet-shaped polymer dispersion type liquid crystal. The light reflection plate 7 is coated on the entire surface of the liquid crystal sheet 6 facing the display substrate in a uniform state.

The inspection element 4 is such that the light transmittance changes depending on the magnitude of the electric field created in the liquid crystal sheet 6. Therefore, as the liquid crystal to be sealed in the liquid crystal sheet 6, the spherical size of the polymer enclosing the substantially spherical liquid crystal is adjusted, and when the electric field is turned on and off, the refractive index of the polymer and that of the liquid crystal are matched or mismatched. A liquid crystal or the like in which a transparent or opaque appearance or a format in which a light transmission or scattering state appears by controlling the arrangement of liquid crystal molecules is suitable. That is, the inspection element 4 used in the present invention is a polymer-dispersed liquid crystal as long as its optical properties such as light transmittance and polarization amount of reflected light change at a constant rate when an electric field is applied. It is not limited.

Next, a method of inspecting the display substrate A using the display substrate inspecting apparatus of the first embodiment having the above-mentioned structure will be described.

First, in the production line of the display substrate A, various processes such as a thin film forming process, a resist process, an exposure process, an etching process and a cleaning process are performed, and then the source wiring 15, the gate wiring 16 and the pixel electrode are formed on the substrate. 9 ...
The display substrate A is manufactured by forming the switching element 17 with.

Then, the inspection element 4 is brought close to the display substrate A manufactured as described above. At this time, a minute air gap 8 is provided between the display substrate A and the inspection element 4, and the display substrate A and the inspection element 4 are placed and fixed in a parallel state. Then, the electrodes of the voltage applying device 10 are connected to the circuit of the display substrate A to apply a voltage. By this operation, the thin film transparent electrode 5 on the upper surface of the inspection element 4 and the pixel electrode 9 on the display substrate A ...
・ An electric field is generated between and.

When the above-mentioned liquid crystal sheet 6 made of polymer-dispersed liquid crystal or the like is used as the inspection element 4, when the electric field as described above is not applied to the liquid crystal sheet 6, FIG. As shown in FIG. 11, the spherical liquid crystal molecules in the liquid crystal sheet 6 are oriented in a disordered direction to scatter light and not transmit light, but when an electric field is applied, as shown in FIG. In addition, the liquid crystal molecules in the sphere are oriented in the same direction and transmit light.

In particular, when a polymer dispersed liquid crystal is used for the liquid crystal sheet 6, there is a region where the amount of transmitted light changes substantially linearly when the voltage is changed, and the linearity of this portion is utilized to make the voltage The change can be captured as a change in the amount of transmitted light. Further, a bias voltage is applied between the pixel electrodes 9 ... And the thin film transparent electrode 5 above the inspection element 4 at a voltage corresponding to this linear region.

When the liquid crystal sheet 6 is used for the inspection element 4 as described above, an electric field generated by applying a voltage between the pixel electrodes 9 ... And the thin film transparent electrode 5 on the upper surface of the liquid crystal inspection element 4. The inspection element 4 that has received the
・ When the electric field changes due to, the amount of transmitted light will change accordingly.

In addition, the light intensity of the light radiated from the light source 1 to the inspection element 4 and transmitted through the inspection element 4 and reflected by the light reflecting plate 7 to pass through the inspection element 4 again is detected by the light receiver 2.
To measure. Then, the control section calculates the light received by the light receiver 2 to calculate the equivalent voltage. Therefore, in order to decide whether to adopt the display substrate A, a certain designated standard is set,
For example, in the display substrate A of 310,000 pixels, if the number of defects to be used is determined,
The user can determine whether or not the display substrate A is adopted from the data of the processed image.

If it is found that the number of defects of the display substrate A is within the allowable range, the inspection-completed display substrate A is transferred to the next production line. Here, in the case where the number of defects of the display substrate A is out of the allowable range,
Those that can be repaired can be repaired and returned to the next production line after repairing. However, if it is considered difficult to repair, it will be discarded.

As described above, the present invention reproduces a state close to the conventional final inspection in the state of the display substrate A before the liquid crystal display panel is assembled, and detects a defect, which is necessary for repairing the defect. Since it is before assembling the liquid crystal display panel, it can be relatively easily performed, and since it is not necessary to put a defective substrate in a subsequent process, unnecessary cost increase is eliminated.

In the method of the present invention, as described above, before assembling the liquid crystal display panel, at each manufacturing stage,
Since it is possible to inspect the defect easily and finely, comparing with the number of defective products in the conventional production product,
It is possible to extremely reduce defective products.

The display substrate inspection method according to the first embodiment can be implemented easily and at low cost, and the defective portion can be reliably eliminated at each production stage. Can be produced at low cost.

Therefore, if the display substrate A is inspected as described above, the position and number of defects of the display substrate A can be electrically displayed, so that the display substrate A can be inspected very easily. Further, since it is possible to collectively convert the reflected light from the inspection element 4 into an equivalent voltage and determine the defect, it is possible to perform the inspection quickly in a short time.

(Embodiment 2) In the display substrate inspection apparatus of Embodiment 2 shown in FIG. 3, an air gap 8 is formed between the inspection element 4 and the display substrate A in the display inspection apparatus of Embodiment 1 described above. Reflector 7 which is not provided and is provided on the bottom surface of the liquid crystal sheet 6.
The surface of the liquid crystal sheet 6 is made of an insulating material.
Is a mixture of a polymer-dispersed liquid crystal and a binder made of a polymer, for example, a composition having a deformation rate of 10% or more. The rest of the configuration is similar to that of the first embodiment described above.

Therefore, the display substrate A and the inspection element 4
When the display substrate A is inspected by closely contacting it as shown in FIG. 4 without forming an air gap between the liquid crystal sheet 6 and the binder, the liquid crystal sheet 6 contains a polymer dispersion type liquid crystal and a binder composed of a polymer. Is a composition having a deformation rate of 10% or more, and needs to have flexible properties. Therefore, in particular, the display substrate A and the inspection element 4 are used.
Does not damage the pixel electrode 9 even if they adhere to each other,
Since the transmittance changes minutely according to the minute electric field emitted from the minute pixel electrode 9, it is possible to inspect the display substrate A having excellent resolution and having the minute pixel electrode 9 ...

The reason why the surface of the reflection plate 7 is limited to the insulating one is that in the second embodiment, as shown in FIG. 4, the reflection plate 7 is placed on the surface of the inspection element 4 facing the display substrate. The entire surface is coated in a uniform state, and in order to perform an inspection in such a state that the display substrate A and the inspection element 4 are in close contact with each other, if the reflection plate 7 is made of metal, in the vicinity of the defective portion, This is because even a portion that is not a defective portion has a connection relationship with the defective portion and a short circuit occurs.

(Embodiment 3) In the display substrate inspection apparatus of Embodiment 3 shown in FIG. 5, the reflection plate 7 provided on the bottom surface of the liquid crystal sheet 6 in the display substrate inspection apparatus of Embodiment 2 has the pixel It is configured by forming a plurality of reflectors 7a having a shape smaller than the space between the electrodes. The rest of the configuration is similar to that of the display substrate inspection apparatus of the second embodiment described above.

Reflector 7 provided on the bottom surface of the liquid crystal sheet 6.
Then, as shown in FIG. 6, the reflectors 7a which are smaller than the space between the pixel electrodes 9 (size: about 100 μm × 100 μm) of the display substrate A are not formed so as to cover the entire surface of the liquid crystal sheet 6. By providing a plurality of pixels, it is possible to prevent the pixel electrodes 9 ... from being bridged by the reflectors 7a .. Avoid short circuits other than defective parts due to connection relationships. Therefore, the third embodiment
With the above-mentioned configuration, even if the reflectors 7a ... Are made of metal, it is possible to accurately inspect a defective portion of the display substrate A.

Further, as explained in the second embodiment, the liquid crystal sheet 6 is composed of a polymer dispersion type liquid crystal having a deformation rate of 10% or more having a flexible property and a polymer, so that Even if the display substrate A and the inspection element 4 are brought into close contact with each other, the pixel electrode 9 ...
The display substrate having finer pixel electrodes 9 has excellent resolution because the transmittance is finely changed according to the fine electric field generated from the fine pixel electrodes 9 ... A inspection is possible.

The reflector 7a, which is the feature of the third embodiment described above, is provided between the inspection element 4 and the display substrate A as in the display inspection apparatus having the configuration shown in FIGS. 7 and 8. It can also be applied to an inspection apparatus for a display substrate having a structure in which the air gap 8 is formed in the.

(Embodiment 4) FIG. 12 shows a schematic structure of a main part of an inspection apparatus according to Embodiment 4. 12
In the display substrate inspection apparatus of the present Example 4 shown in FIG. 4, a transmissive polymer dispersed liquid crystal is particularly used for the inspection element 4,
The light receiving device 2 receives the detection light generated when a voltage is applied to the light receiving device 2, and the image processing computer 3 connected to the light receiving device 2. The display substrate A can be arranged on the opposite surface of the inspection element 4.

Therefore, the display board inspecting apparatus of the fourth embodiment differs from the display board inspecting apparatus of the first to third embodiments described above in that the inspection element 4 uses a transmissive polymer type liquid crystal. Then, as shown in FIG. 12, by placing the light source 1 on the lower surface side of the display substrate A without forming the reflection plate 7 on the liquid crystal sheet 6, the inspection element 4 on which the detection light is incident by the light source 1 is placed. The light receiving device 2 receives the transmitted light from the image receiving device 2 and the image processing computer 3 connected to the light receiving device 2.

Therefore, in the display substrate inspection method using the display substrate inspection device of the fourth embodiment, first, the inspection element 4 is brought close to the display substrate A. At this time, a minute air gap 8 is provided between the display substrate A and the inspection element 4, and the display substrate A is
And the inspection element 4 are placed and fixed in parallel with each other. Subsequently, the voltage applying device 10 is applied to the circuit of the display substrate A.
The electrodes are connected and a voltage is applied. By this operation, an electric field is generated between the thin film transparent electrode 5 on the upper surface of the inspection element 4 and the pixel electrode 9 on the display substrate A.

When a liquid crystal sheet 6 made of a transmissive polymer-dispersed liquid crystal or the like is used for the inspection element 4, the electric field as described above is not applied to the liquid crystal sheet 6, as shown in FIG. As shown in the figure, the spherical liquid crystal molecules in the liquid crystal sheet 6 are oriented in a disordered direction to scatter light and not transmit light, but when an electric field is applied, as shown in FIG. , The liquid crystal molecules in the sphere are oriented in the same direction and transmit light.

When a transmissive polymer dispersed liquid crystal is used for the liquid crystal sheet 6, there is a region where the amount of light transmission changes linearly when the voltage is changed. A change in voltage can be captured as a change in the amount of transmitted light. Further, a bias voltage is applied between the pixel electrodes 9 ... And the thin film transparent electrode 5 above the inspection element 4 at a voltage corresponding to this linear region.

When the liquid crystal sheet 6 is used for the inspection element 4 as described above, an electric field generated by applying a voltage between the pixel electrodes 9 ... And the thin film transparent electrode 5 on the upper surface of the liquid crystal inspection element 4. The inspection element 4 that has received the
・ When the electric field changes due to, the amount of transmitted light will change accordingly.

Further, the inspection element 4 is irradiated with light from the light source 1 through the display substrate A, and the intensity of the light transmitted through the inspection element 4 is measured by the light receiver 2. Then, the light received by the light receiver 2 is calculated by the control unit to calculate an equivalent voltage. Therefore, to decide whether to adopt the display substrate A,
Similar to the first embodiment described above, if a certain reference is set and the value of how many defects are used in the display substrate A having 310,000 pixels is determined, the user can process the data of the processed image. It is possible to judge whether the display substrate A is adopted or not.

When it is determined that the number of defects of the display substrate A is within the allowable range, the inspection-completed display substrate A is transferred to the next production line. Here, in the case where the number of defects of the display substrate A is out of the allowable range,
Those that can be repaired can be repaired and returned to the next production line after repairing. However, if it is considered difficult to repair, it will be discarded.

Therefore, the display board A is checked by the display board inspection apparatus of the fourth embodiment as described above.
If the inspection is performed, the position and the number of defects of the display substrate A can be electrically displayed, so that the inspection of the display substrate A can be performed very easily. Further, since it is possible to collectively convert the transmitted light from the inspection element 4 into an equivalent voltage and determine the defect, it is possible to perform the inspection quickly in a short time.

Although the air gap 8 is provided between the liquid crystal sheet 4 and the pixel electrodes 9 of the display substrate A in the fourth embodiment described above, the liquid crystal is formed as shown in FIGS. 14 and 15. With the configuration in which the sheet 4 and the pixel electrodes 9 ... Of the display substrate A are brought into close contact with each other, the same effect as that of the display substrate inspection apparatus of the fourth embodiment can be obtained.

(Embodiment 5) FIG. 17 shows a schematic structure of a main part of an inspection apparatus according to Embodiment 5. FIG. 17
The display substrate inspection apparatus of the fifth embodiment shown in FIG. 5 uses the thin film EL element 25 as the inspection element 4, and receives the detection light generated when a voltage is applied to the light reception element 2 and the light reception element 2. It is equipped with a connected image processing computer 3. The display substrate A can be arranged on the opposite surface of the inspection element 4.

Reference numeral 10 in the drawing is a voltage applying device for applying a constant voltage between the thin film transparent electrode 20 on the upper surface of the inspection element 4 and the display substrate A, and includes a switch and a power supply section. As shown in FIG. 17,
A voltage can be applied from the gate wiring 16 and the source wiring 15 to the thin film transparent electrode 20 of the EL element of the inspection element 4 and all the pixel electrodes 9 on the display substrate A. The voltage applying device 10 can apply a pulse voltage to each of the source wiring 15 and the gate wiring 16, and can change the pulse voltage, the pulse width, and the period.

The display substrate A to be inspected in the fifth embodiment has the same structure as the display substrate A shown in FIG. 9 described in the first embodiment. In addition,
Various structures are known for the wiring structure of the display substrate, the structure of the pixel electrode 9 and the structure of the switching element 17, but any kind of structure can be applied to the inspection apparatus of the present invention. So display board A
The structure of is not particularly limited.

Therefore, the structure and principle of the thin film EL element used for the inspection element 4 which is the feature of the fifth embodiment will be described below. The thin film EL device has a structure as shown in FIG.
This thin film EL element 25 is made of a heavy insulator structure.
Is the transparent electrode 20, the first insulating layer 21, and the EL light emitting layer 22.
And the second insulating layer 23,
They are sequentially stacked on top. And the thin film EL
The basic operation principle of the device is that when a voltage is applied to the EL light emitting layer 22 made of the phosphor material in the thin film EL device, electrons (or holes) in the material are accelerated and exist in the phosphor. The emission center is collisionally excited, and light is emitted when the excited emission center returns to the ground state. This light emission is called EL.

That is, in the inspection apparatus for the display A of the fifth embodiment, the second insulating layer 23 side of the above-mentioned thin film EL element and the pixel electrode 9 side of the display substrate A are placed in parallel,
Between the transparent electrode 20 of the thin film EL element and the pixel electrode 9 of the display substrate A ...
An electric field generated when a voltage of z is applied excites the active species ions in the EL light emitting layer 22 in the thin film EL element having the above structure to emit light. Therefore, it is possible to detect a defect in the pixel electrode of the display substrate A due to the abnormal light emitting state.

Therefore, in the display substrate inspecting apparatus of the fifth embodiment, by using the thin film EL element having the above structure as the inspecting element 4, it is possible to reduce the thickness of the apparatus and further reduce the applied voltage. Reduction can be achieved. In addition, in the display substrate inspection apparatus of the fifth embodiment described above, as shown in FIGS. 17 and 18, the air gap 8 is provided between the pixel electrode 9 of the display substrate A and the second insulating layer 23 of the thin film EL element. The defect inspection of the pixel electrodes 9 ... Of the display substrate A can be performed even in the provided state. However, as shown in FIG. 19, the pixel electrodes 9 ...
Even when the thin film EL element and the second insulating layer 23 of the thin film EL element are in close contact with each other, defects of the pixel electrodes 9 ... Of the display substrate A can be detected.

(Embodiment 6) The display substrate inspection apparatus of this Embodiment 6 uses a thick film EL element instead of the thin film EL element as the inspection element 4 in Embodiment 5. The thick film EL element has a structure as shown in FIG. 21, and reference numeral 31 in the drawing is a body of the thick film EL element. The thick film EL element 31 includes a transparent electrode 27,
The EL light emitting layer 28 and the insulating layer 29 are sequentially laminated on the substrate 26. The transparent electrode 27 and the display substrate A
Between the pixel electrodes 9 ...
When a voltage of Hz is applied, active species ions in the EL light emitting layer 28 are excited to emit light.

That is, the display substrate A according to the sixth embodiment.
In the inspection apparatus of No. 3, as in the thin film EL element used for the inspection element 4 in the above-described fifth embodiment, the insulating layer 29 side of the thick film EL element is placed on the opposing surface on the display substrate A side, and the transparent electrode 2
6 side is placed in parallel so as to be the opposite side to the facing surface of the liquid crystal display substrate A, and between the transparent electrode 27 of the thick film EL element and the pixel electrode 9 of the display substrate A. When a voltage of several tens Hz to several kHz is applied,
The active species ions of the EL light emitting layer 28 are excited to emit light. This abnormal light emitting state can be understood as a defect of the pixel electrode of the display substrate A.

The thick film EL element, which is a feature of the display substrate inspection apparatus of the sixth embodiment, is different from the thin film EL element used for the inspection element 4 of the above-described fifth embodiment in that the EL light emitting layer is completely an insulating layer. It is not a sealed structure, but an insulating layer is provided only on one surface of the EL light emitting layer, and it is impossible to completely cut off moisture from the outside or a current flowing in directly, and the life thereof is the thin film EL. Although it is shorter than the element, the thick film EL element can be formed in a large size at a low cost, and by forming the substrate 26 not only with glass but with a plastic sheet or the like, it is flexible and large. The plate can be easily formed at low cost, and its function can be sufficiently exerted as an inspection component that does not assume continuous use such as inspection of a display substrate. In the inspection device for the display substrate having the same configuration as in the second and third embodiments described above, the thick film EL element can be used as the inspection element 4 as in the sixth embodiment.

Hereinafter, a manufacturing example of the display substrate inspection apparatus according to each of the above embodiments will be described. (Manufacturing Example 1) This Manufacturing Example 1 has the same configuration as the display substrate inspection apparatus shown in FIG. 1, and includes a light source 1 including a halogen lamp and an inspection element 4 on which detection light is incident by the light source 1. Receiver 2 using a CCD (charge-coupled device) type camera that receives reflected light from
The image processing computer 3 connected to the inspection element 4 is provided, and the display substrate A can be arranged on the opposite surface of the inspection element 4. An air gap 8 of about 1.0 to 30 μm is formed between the inspection element 4 and the display substrate A.

The inspection element 4 had a thickness of 10 μm in which a polymer dispersion type liquid crystal was mixed with a binder made of an ultraviolet curable resin (NoA-65 manufactured by Norland Co.) at a weight ratio of 1: 1.
The liquid crystal sheet 6 is about m. The liquid crystal sheet 6 has a bottom surface on which a light reflection plate 7 of a vapor deposition film made of Al having a thickness of about 0.2 μm is formed or attached.
A thin film transparent electrode made of indium tin oxide (ITO) and having a thickness of about 0.07 μm is formed on the upper surface of the liquid crystal sheet 6.

Then, in the inspection device for the display substrate A using the polymer dispersion type liquid crystal for the inspection element 4 as in the above-mentioned constitution, the light transmittance with respect to time was measured, and the result is shown in FIG. As shown in FIG. 16, in the display substrate composed of the polymer dispersion type liquid crystal for the inspection element 4, the liquid crystal instantly reacts at ON-0FF of the switch, and the transparency / opacity can be freely set. You can see that you can control it.

(Manufacturing Example 2) The display substrate inspecting apparatus of this Manufacturing Example 2 is different from that of Manufacturing Example 1 in that the inspection element 4 and the display substrate A are placed in close contact with each other, and Display substrate A of the inspection element 4
Is not formed uniformly on the entire surface of the inspection element 4, and the shape reflection having a width smaller than the interval between the pixel electrodes 9 of the display substrate A. The configuration is such that a plurality of bodies 7a ... Is provided, and the configuration is similar to that of the display substrate inspection apparatus shown in FIG.

The inspection element 4 is made of a polymer-dispersed liquid crystal which is an ultraviolet curable resin (NoA-65 manufactured by Norland).
Rubber isoprene mixed into a mixture consisting of a binder consisting of 1: 1 by weight, with a thickness of 10 μm.
It is a liquid crystal sheet. The bottom surface of the liquid crystal sheet 6 is made of Al having a thickness of about 0.2 μm and is 10 μm ×
A plurality of light reflectors 7a each having a vapor deposition film of 10 μm in shape are formed by coating or adhering the light reflectors 7a. The upper surface of the liquid crystal sheet 6 is made of indium tin oxide (I).
TO) thin film transparent electrode 5 with a thickness of about 0.07 μm
Are formed.

As described above, the reflection plate provided on the bottom surface of the liquid crystal sheet 6 is not formed on the entire surface of the liquid crystal sheet 6, but the pixel electrodes 9 of the display substrate A (size: 100).
By providing a plurality of reflectors 7a having a width smaller than the distance between the display substrate A and the reflectors 7a ... The connection between the defective portion and the normal portion due to the close contact can be avoided, and the defective portion of the display substrate A can be inspected reliably.

Further, in the display substrate inspection apparatus of the second manufacturing example, the liquid crystal inspection element 4 uses a flexible inspection element 4 in which a polymer-dispersed liquid crystal and an ultraviolet curable resin are mixed with rubber-like isoprene. By doing so, the adhesiveness between the display substrate A and the inspection element 4 is particularly good, and the transmittance changes minutely according to the minute electric field generated from the minute pixel electrodes 9 ... Excellent,
The display substrate A having the finer pixel electrodes 9 ... Can be inspected. Further, as described above, by using the inspection element 4 flexibly, it is possible to inspect the display substrate without damaging the thin film transistor (TFT) of the display substrate A and producing no defective product due to the inspection.

(Manufacturing Example 3) The display inspecting apparatus of Manufacturing Example 3 has the same structure as that of the display substrate inspecting apparatus shown in FIG. It is equipped with a photodetector 2 using a CCD type camera that receives the emitted light of, and an image processing computer 3 connected to the photodetector 2, so that the display substrate A can be placed on the opposite surface of the inspection element 4. Is becoming An air gap of about 1.0 to 30 μm is formed between the inspection element 4 and the display substrate A.

The structure of the thin film EL element used for the liquid crystal inspecting element 4, which is the feature of the third manufacturing example, will be described with reference to FIG. The thin film EL element has a double insulating structure as shown in FIG. 20, and reference numeral 25 in the figure denotes a thin film EL element.
It is the body of the device. The thin film EL element 25 is made of indium tin oxide (ITO) and has a thickness of 0.1 μm to 0.1 μm.
A transparent electrode 20 having a thickness of about 2 μm and a tantalum oxide (Ta ₂ O ₅ ) film coated on the upper surface of the transparent electrode 20 having a thickness of 0.2 to 0.3 μm.
A thickness of a first insulating layer 21 of m and a phosphor in which a luminescent center is formed by adding a sizing agent such as Mn to zinc sulfide (ZnS) formed on the upper surface of the first insulating layer 21. 0.5μ
m to 1.0 μm EL light emitting layer 22 and the EL light emitting layer 22
A light emitting portion 25a composed of a second insulating layer 23 having the same structure as the first insulating layer coated on the upper surface is provided on a transparent substrate 19 made of glass.
Each of the layers forming the thin film EL element 25 is a thin film formed by vacuum deposition or sputtering.

Then, the thin film EL element 2 having the above structure
5 is that when a voltage of several tens Hz to several kHz is applied between the transparent electrode 20 and the pixel electrode 9 of the display substrate A, active species ions in the EL light emitting layer 22 are excited. It emits light.

That is, the display substrate A of the third manufacturing example.
In the inspection apparatus, the second insulating layer 23 side of the thin film EL element having the above-described configuration is on the facing surface side of the display substrate A, and the transparent substrate 19 side is on the opposite side of the facing surface of the display substrate A. When the voltage of several tens Hz to several kHz is applied between the transparent electrode 20 of the thin film EL element 25 and the display substrate A, the active species ions in the EL light emitting layer 22 are It is excited to emit light. This is a mechanism by which this abnormal light emitting state can be recognized as a defect in the pixel electrode 9 ... Of the display substrate.

Therefore, by using the thin film EL element having the above structure as the inspection element 4 of the inspection apparatus for the display substrate as described above, it is possible to make the apparatus thin and further reduce the applied voltage. Can be planned. In the third manufacturing example, the air gap 8 is provided between the inspection element 4 and the pixel electrode 9 ... Of the display substrate A, but the air gap 8 is not provided, and the inspection element 4 and the pixel of the display substrate A are not provided. Even if the electrodes 9 are brought into close contact with each other, the same effect as that of the third manufacturing example can be obtained.

(Manufacturing Example 4) Further, in the above-described Manufacturing Example 3, a thin film EL element was used as the inspection element 4, but in this Manufacturing Example 4, the thick film E having the following structure was used.
It uses an L element.

The structure of the thick film EL element used for the inspection element 4, which is the feature of the fourth manufacturing example, will be described with reference to FIG. As shown in FIG. 21, the thick film EL element includes a transparent electrode 27 made of indium tin oxide (ITO) or the like and having a thickness of about 0.07 μm, and zinc sulfide (ZnS) on the upper surface thereof.
A mixed film in which a phosphor having a thickness of 5 to 10 μm, to which a sizing agent such as copper (Cu) or chlorine (Cl) is added, and a binder made of isocyanoethylcellulose is mixed with the phosphor, is formed to have a thickness of 10 μm to 20 μm. The EL light emitting layer 28 formed in
A light emitting portion 31a made of TiO ₂ coated on the upper surface of the thick film EL element 28 and an insulating layer 29 in which a binder made of isocyanoethyl cellulose is mixed is provided on the upper surface of a substrate 26 made of glass.

In the thick film EL element having the above structure, when a voltage of several 10 Hz to several kHz is applied between the transparent electrode 27 and the pixel electrode 9 of the display substrate A. The active species ions in the light emitting layer 28 are excited to emit light.

That is, the display substrate inspecting apparatus of the fourth manufacturing example has the same insulating layer 2 of the thick film EL element as the thin film EL element used for the inspecting element 4 of the third manufacturing example.
With the 9 side facing the display substrate A, the transparent substrate 26
Is placed in parallel so that the side thereof is opposite to the facing surface of the display substrate A, and a few lines are placed between the transparent electrode 27 of the thick film EL element and the pixel electrode 9 of the display substrate A. When a voltage of 10 Hz to several kHz is applied, the active species ions in the EL light emitting layer 28 are excited to emit light. This is a mechanism by which this abnormal light emitting state can be recognized as a defect in the pixel electrode 9 ... Of the display substrate A.

The thick film EL element, which is a feature of this Production Example 4, is the thin film E used in the inspection element 4 of Production Example 3 described above.
Unlike the L element, the EL light emitting layer is not completely sealed with an insulating layer, and it is impossible to cut off moisture from the outside or a direct inflowing current and the life is shorter than that of the thin film EL element. In the thick film EL element, large plate formation can be realized at low cost, and by forming the substrate 26 with a plastic sheet or the like instead of glass, flexible large plate formation can be performed easily and at low cost. Can be manufactured,
As an inspection part that does not assume continuous use such as inspection of a display board, it can fully demonstrate its function.

[0079]

As described above, according to the present invention, the inspection element is installed on the display substrate to be inspected, and the pixel electrode of the display substrate and the thin film transparent electrode on the upper surface of the inspection element are energized to detect the optical element of the inspection element. By changing the optical property and capturing the change in the intensity of the light passing through the inspection element in that state with the light receiver and converting it into an equivalent voltage, it is possible to detect the defect of the display substrate, so the detection output of the light receiver It is possible to electrically detect defects on the display board,
There is a feature that allows accurate and quick inspection.

If a liquid crystal sheet made of polymer dispersed liquid crystal is used as an inspection element, a defective portion can be detected by the transmittance of light passing through the liquid crystal sheet, and an EL element is used instead of the liquid crystal sheet. By
It is possible to detect a defective portion depending on the presence / absence and the degree of light emission.

Further, in the case where a light reflector is provided at the bottom of a transparent case in which liquid crystal is sealed as an inspection element used in the inspection device, the light emitted from the light source to the liquid crystal is reflected by the light reflector. Since it can be received by the light receiver, it is suitable as an inspection element for the inspection device. In addition, in the case of an inspection element using this liquid crystal, the transmittance changes minutely according to the minute electric field emitted from the minute pixel electrode, so it has excellent resolution and can be used for inspection of display substrates with finer pixel electrodes. It is suitable.

Further, in the method of the present invention, defects can be easily and finely inspected in each manufacturing stage before assembling the liquid crystal display panel as described above, and therefore, in the conventional products. Compared with the number of defective products, the number of defective products can be extremely reduced and the yield can be improved.

Further, the method of inspecting the display substrate in the method of the present invention can be realized easily and at low cost, and it is possible to surely eliminate the defective portion at each production stage. It can be realized at low cost.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a display board inspection apparatus according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a schematic diagram showing a display board inspection apparatus according to a second embodiment of the present invention.

FIG. 4 is an enlarged view of a main part of FIG.

FIG. 5 is a schematic diagram showing a display board inspection apparatus according to a third embodiment of the present invention.

FIG. 6 is an enlarged view of a main part of FIG.

FIG. 7 is a schematic diagram showing a modification of the display substrate inspection apparatus of the first embodiment shown in FIG.

FIG. 8 is an enlarged view of a main part of FIG. 7.

FIG. 9 is a partially enlarged view of a display board to be inspected by the apparatus shown in FIGS.

FIG. 10 is a cross-sectional view of a liquid crystal sheet in a state where no electric field is applied.

FIG. 11 is a cross-sectional view of a liquid crystal sheet with an electric field applied.

FIG. 12 is a schematic diagram showing a display board inspection apparatus according to a fourth embodiment of the present invention.

FIG. 13 is an enlarged view of a main part of FIG.

FIG. 14 is a schematic diagram showing a modified example of the display substrate inspection apparatus of the fourth embodiment.

FIG. 15 is an enlarged view of a main part of FIG.

FIG. 16 is a diagram showing the light transmission characteristics of the polymer-dispersed liquid crystal used for the inspection element in the display substrate inspection apparatus of Production Example 1 according to the present invention.

FIG. 17 is a schematic diagram showing a display board inspection apparatus according to a fifth embodiment of the present invention.

FIG. 18 is an enlarged view of a main part of FIG.

FIG. 19 is a diagram for explaining a modified example of the display substrate inspection apparatus according to the fifth embodiment.

FIG. 20 is a cross-sectional view showing the structure of a thin film EL element.

FIG. 21 is a cross-sectional view showing a configuration of a thick film EL element.

[Explanation of symbols]

 1 Light source 2 Light receiver 3 Image processing computer 4 Inspection element 4a Substrate 5 Thin film transparent electrode 6 Liquid crystal sheet 7 Reflector 7a Reflector 8 Air gap 9 Pixel electrode 10 Voltage application device 11 Fixed stand 12 Signal supply circuit 13 Scanning circuit 15 Source wiring 16 Gate Wiring 17 Switching Element 18 Liquid Crystal 18a Binder 19 Substrate 20 Transparent Electrode 21 First Insulating Layer 22 EL Light Emitting Layer 23 Second Insulating Layer 25 Thin Film EL Element 25a Light Emitting Part 26 Substrate 27 Transparent Electrode 28 EL Light Emitting Layer 29 Insulating Layer 31 Thickness Membrane EL element 31a Light emitting part A Display substrate

Claims (6)

[Claims] 1. An apparatus for inspecting a display substrate having a plurality of pixel electrodes formed on a substrate, comprising: an inspection element which is disposed above the display substrate so as to face each other and whose optical properties change when an electric field is applied; A light source for irradiating the inspection element with light, and irradiating the inspection element,
A light receiver that captures the light emitted from the inspection element, a power supply that applies a voltage between the pixel electrode on the display substrate and the inspection element, and a measuring unit that measures the change in the light captured by the light receiver. An apparatus for inspecting a display substrate, comprising: 2. An inspection device for a display substrate, wherein the inspection element according to claim 1 is a polymer-dispersed liquid crystal. 3. An apparatus for inspecting a display substrate having a plurality of pixel electrodes formed on the substrate, wherein an inspection element composed of an electroluminescence element whose optical properties change when an electric field is applied, and an inspection element formed from this inspection element. A light source that captures the captured light, a power supply that applies a voltage between the pixel electrode and the inspection element on the display substrate, and a measuring unit that measures a change in the light captured by the light receiver. An inspection device for a display board, which is characterized in that 4. A method of inspecting a display substrate comprising a plurality of pixel electrodes formed on a substrate, wherein an inspection element whose optical property changes when an electric field is applied is arranged on the display substrate, A voltage is applied between the pixel electrode of the substrate and the inspection element, an electric field is applied to the inspection element, and a partial change in the optical property of the inspection element is detected to detect whether the pixel electrode of the display substrate is good or bad. A method for inspecting a display substrate, which comprises detecting 5. A method for inspecting a display substrate, wherein the inspection element according to claim 4 is a polymer-dispersed liquid crystal. 6. The method of inspecting a display substrate according to claim 4, wherein the inspection element is an electroluminescence element.