KR101259646B1 - Apparatus and method for contactless test of flat panel display using electro-optic effect - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact inspection apparatus for flat display devices, and more particularly, to an apparatus for non-contact inspection of both sides of a flat display device by electrooptically acquiring a voltage distribution on the flat display device.

The non-contact inspection device for a flat panel display device according to the present invention includes a light source disposed to be spaced apart from one surface of an inspected object that is a flat display device to emit light to pass through the inspected object, and the light path of the light emitted from the light source. A modulator arranged to be spaced apart from the other surface of the test object, the modulator configured to modulate the optical characteristics of the light in proportion to the voltage distribution on the surface of the test subject, and a modulation sensing unit configured to sense modulated optical characteristics of the light passing through the modulator It is characterized by.

Flat Panel Display, LCD, Non-Contact, Inspection, Voltage, Electro-Optical, Modulator.

Description

Non-contact inspection device and inspection method for flat display device using electro-optic effect {APPARATUS AND METHOD FOR CONTACTLESS TEST OF FLAT PANEL DISPLAY USING ELECTRO-OPTIC EFFECT}

1 is an explanatory diagram of an embodiment of a non-contact inspection device according to the present invention,

2A is a cross-sectional view of one embodiment of a modulator of the embodiment of FIG. 1, FIG.

2B is a cross-sectional view of another embodiment of the modulator of the embodiment of FIG. 1;

3 is an explanatory view of another embodiment of a non-contact inspection device according to the present invention;

Figure 4 is a flow chart showing one embodiment of a non-contact inspection method according to the present invention.

<Explanation of symbols for the main parts of the drawings>

50: test object 100: light source

200: modulator 210: upper glass plate

211: conductive layer 220: lower glass plate

221: auxiliary conductive layer 240: sealing material

250: modulation layer 260: conductor

270: spacer 300: modulation detection unit

310: first polarization filter, lower polarization filter

320: second polarization filter, upper polarization filter

321: phase delay 400: optical lens group

500: auxiliary optical lens group 600: inspection table

700: housing

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact inspection apparatus for flat display devices, and more particularly, to an apparatus for non-contact inspection of both sides of a flat display device by electrooptically acquiring a voltage distribution on the flat display device.

Recently, flat display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), organic light emitting diodes (OLEDs), and the like have been widely used for displaying images.

In order to meet the demand for a clearer screen, these flat display devices are also getting higher resolution. Taking a thin film transistor liquid crystal display (TFT LCD) as an example, one pixel has a width of 0.1 mm, but three sub pixels each responsible for R, G, and B for color image processing. In the case of the active matrix method, a pixel electrode and a switching element, that is, a TFT, must be formed inside each pixel. For example, a TFT LCD requires 1.19 million pixels to have a resolution of 1600 × 1200, and 576 million are required for the number of sub pixels. As the resolution increases, the required number of pixels increases more rapidly. Accordingly, the manufacturing process of the flat panel display device requires more and more precision.

This improvement in the precision required in the manufacturing process increases the possibility of defects together, thus increasing the necessity of inspecting whether each pixel of the manufacturing process is properly formed. Therefore, the technology regarding the inspection apparatus and the inspection method is also developed together.

The pixels of a TFT LCD have a conductive layer such as indium tin oxide (ITO) together with a thin film transistor (TFT) formed directly on a glass plate. Since the mechanical strength thereof is low, the probe pin is directly connected to the pixel. Contact inspection, which checks for normal operation by contact, can damage the pixels. Each pixel also has an insulating layer added over the deposited structure, in which case it is impossible to make contact inspection because the probe pin cannot be contacted. In particular, the mechanical precision of the probe pin must be increased together with the trend of increasing pixel density. Since the precision of the processing of the probe pin is also limited, the development of a non-contact inspection device and an inspection method that can replace such contact inspection in recent years. This is going on.

Non-contact inspection of the flat panel display is made by using an electro-optic effect. Electro-optic effect refers to the effect of changing the optical properties of a particular material in an electric field that changes slowly relative to the frequency of light. For example, some crystals change their optical ellipticity in proportion to the electric field size in the electric field, which is called the Pockel's Effect, which is a representative example of the electro-optic effect.

When a TFT LCD applies power to a pixel including a TFT formed on its surface, the voltage is distributed in a predetermined pattern according to the relative positions of a plurality of pixel electrodes distributed in the pixel. Therefore, by measuring the voltage distribution and contrasting it with the normal voltage distribution, it is possible to check whether the pixel is operating properly.

In order to measure such voltage distribution in a non-contact manner, an inspection apparatus is known in which a light source, an electro-optic modulator, an object under test, and a camera are arranged on the same axis.

According to this inspection apparatus, the light from the light source passes through the electro-optic modulator and the inspected object sequentially, and the optical properties of the modulator are changed by the electric field formed between the modulator and the inspected object. Therefore, the light entering the electro-optic modulator changes its characteristic after passing through the modulator, and enables the camera to acquire the change in the light characteristic as an image so as to determine the voltage distribution of the object under test.

However, there are some difficulties in actually implementing such a non-contact inspection apparatus. For example, since the area of the modulator is smaller than the area of the flat panel display, the inspected object, the inspector must have a structure that allows relative movement between them in order to perform inspection on the entire surface of the flat panel display. At this time, the inspection apparatus requires mechanical devices such as a loading means for loading the flat display device to be inspected into the inspection apparatus, and a position correction means for arranging the flat display apparatus in the correct position, and means for performing the inspection. It is also necessary to ensure that they do not cause spatial interference with the fields. In addition, even if the modulator is a non-contact test that does not directly contact the subject, the modulator is actually placed in close proximity to the subject, so in some cases, there is a possibility that direct contact may occur and damage to the subject may occur. There is a need.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the components necessary for performing the non-contact inspection of the flat display device and the components for loading and positioning the inspected object do not cause spatial interference. It is an object to provide a non-contact inspection apparatus.

In addition, an object of the present invention is to provide a non-contact inspection apparatus capable of performing the inspection smoothly over the entire area of the flat display device while moving horizontally with respect to the large area flat display device.

Another object of the present invention is to provide a non-contact inspection apparatus that can block the modulator from being electrically connected to the inspected object.

It is still another object of the present invention to provide a method capable of performing a non-contact inspection on a flat panel display device.

Other objects, specific advantages and novel features of the invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings.

The non-contact inspection device for a flat panel display device according to the present invention includes a light source which is disposed spaced apart from one surface of an object to be a flat display device and emits light to pass through the object, and the light path of the light emitted from the light source. A modulator arranged to be spaced apart from the other surface of the test object, the modulator configured to modulate the optical characteristics of the light in proportion to the voltage distribution on the surface of the test subject, and a modulation sensing unit configured to sense modulated optical characteristics of the light passing through the modulator It is characterized by.

In the non-contact inspection device for a flat panel display device according to the present invention, it is preferable that the optical lens group further comprises diffusing or concentrating light emitted from the light source to the object under test.

In the non-contact inspection apparatus for a flat panel display device according to the present invention, the modulator may include an upper glass plate, a conductive layer coated on the entire lower surface of the upper glass plate, and spaced downward from the upper glass plate, and spaced downward from the upper glass plate. A lower glass plate having a large area, a sealing material partitioned so that the space between the upper glass plate and the lower glass plate is separated from the outside, and the outer wall faced on the same line as the sidewall of the upper glass plate, and the upper glass plate and the lower glass plate; And a modulating layer filled in a space partitioned by a sealing material and made of an electro-optic material, and a conductor continuously applied from the side of the upper glass plate to the side of the sealing material. The modulator is preferably a sealing material made of a conductive material and disposed along an edge of the lower surface of the upper glass plate, wherein the lower glass plate further includes an auxiliary conductive layer coated on the upper edge of the upper plate. It is preferable to apply even to the auxiliary conductive layer of a lower glass plate. Further, the sealing material is made of a conductive material, and the auxiliary conductive layer of the lower glass plate is more preferably in contact with the sealing material. Spacer inserted to maintain the gap between the upper glass plate and the lower glass plate may be further included. In addition, the modulation layer is characterized in that the liquid crystal (Liquid Crystal) material.

In the non-contact inspection device for a flat panel display according to the present invention, the modulation detection unit includes: a first polarization filter disposed in front of the modulator on the optical path; a second polarization filter disposed behind the modulator; And a camera disposed behind the second polarizing filter.

In addition, the modulation detection unit may further include a phase delay unit disposed immediately before the second polarization filter.

The non-contact inspection device for a flat panel display device according to the present invention preferably further includes an auxiliary optical lens group disposed between the camera and the second polarization filter to diffuse or concentrate the light incident on the camera.

In addition, the non-contact inspection device for a flat panel display device according to the present invention includes an inspection table in which the inspected object, which is a flat display device, is placed horizontally, a light source disposed under the inspection table, and emitting light to pass through the inspected object, and the light source. A lower polarization filter disposed above and polarizing light from the light source and spaced above the test object on an axis of light emitted from the light source, and an ellipticity is changed in proportion to the voltage distribution on the surface of the test object. And an upper polarizing filter installed above the modulator and polarizing the light passing through the modulator, and a camera obtaining a planar image by the light passing through the upper polarizing filter.

In the non-contact inspection apparatus for a flat panel display according to the present invention, the modulator, the upper polarizing filter and the camera further comprises a housing therein, wherein the housing, the light source and the lower polarizing filter are disposed relative to the same optical axis It is preferable to operate in a horizontal direction with respect to the inspection table while maintaining the.

In addition, the non-contact inspection device for a flat panel display device according to the present invention may further include an optical lens group for diffusing or concentrating light emitted from the light source to the test object. The apparatus may further include an auxiliary optical lens group disposed between the camera and the upper polarizing filter to diffuse or concentrate the light incident to the camera.

In the non-contact inspection apparatus for a flat panel display device according to the present invention, the modulator may include an upper glass plate, a conductive layer coated on the entire lower surface of the upper glass plate, and spaced downward from the upper glass plate, and spaced downward from the upper glass plate. A lower glass plate having a large area, a sealing material partitioned so that the space between the upper glass plate and the lower glass plate is separated from the outside, and the outer wall faced on the same line as the sidewall of the upper glass plate, and the upper glass plate and the lower glass plate; And a modulating layer filled in a space partitioned by a sealing material and made of an electro-optic material, and a conductor continuously applied from the side of the upper glass plate to the side of the sealing material. The sealing material is made of a conductive material and is disposed along the edge of the lower surface of the upper glass plate. In addition, the lower glass plate further includes an auxiliary conductive layer coated on the edge of the upper surface, the conductor is preferably applied to the auxiliary conductive layer of the lower glass plate. Further, the sealing material is made of a conductive material, and the auxiliary conductive layer of the lower glass plate is more preferably in contact with the sealing material. The modulator may further include a spacer inserted to maintain a gap between the upper and lower glass plates. In the modulator, the modulating layer is preferably made of a liquid crystal material.

The non-contact inspection method for a flat panel display device according to the present invention includes the steps of horizontally placing a test object as a flat display device on an inspection table, applying an operating power to the test object, a conductive layer is formed on one side, and electro-optical Arranging a modulator made of a material above the object under test, with the conductive layer facing away from the object, applying a reference voltage to the conductive layer of the modulator, and irradiating light from below the object; And measuring the modulated optical characteristics of the light transmitted through the inspected object and the modulator.

In the non-contact inspection method for a flat panel display according to the present invention, measuring the modulated optical characteristics of the light includes the steps of: firstly polarizing the light irradiated from below the object under test before entering the modulator; And secondly polarizing the light passing through the modulator, and acquiring a two-dimensional image by the second polarized light with a camera.

In addition, the non-contact inspection method for a flat panel display device according to the present invention may further include horizontally moving the inspected object with respect to the examination table after obtaining the planar image.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the non-contact inspection apparatus according to the present invention.

1 is an explanatory diagram showing an embodiment of a non-contact inspection apparatus according to the present invention.

The light source 100 emits light toward the object 50 as a means for generating light. The light source 100 is a flat panel display device and is spaced apart from one surface of the test object 50 having a plate shape. Light from the light source 100 penetrates the object 50 and passes through the modulator 200, which will be described below, and modulates optical characteristics such as phase and polarization, thereby sensing the modulated characteristics of the light. This can be referred to as inspection light in that the object 50 is inspected normally. The inspection light is preferably a laser having an even optical characteristic including a phase. Therefore, the light source 100 may include a xenon lamp, a sodium lamp or a light emitting diode (LED), but more preferably includes a laser oscillator.

An optical lens group 400 is preferably disposed between the light source 100 and the object 50 to diffuse, concentrate, or change the optical path of the inspection light. If the area of the cross section perpendicular to the traveling direction of the inspection light is smaller than the inspection area on the inspected object 50, light diffusion is required, and vice versa, when the inspection region of the inspected object 50 is smaller, the inspection is reversed. Concentration of light is necessary. Therefore, the optical lens group 400 may be composed of a single convex lens or a concave lens, or a combination thereof. In addition, the optical lens group 400 may be added with means for changing the optical path, including the reflector, optical fiber, despite its name.

The modulator 200 is disposed to be spaced apart from the other surface of the inspected object 50 on the path of the inspection light, that is, the light path, and is positioned opposite to the light source 100 with respect to the inspected object 50. Therefore, the inspection light transmitted through the object 50 is incident on the modulator 200.

When a power source is connected to an inspection region, for example, one pixel of the inspected object 50, the voltage distribution becomes uneven on the surface of the pixel depending on the arrangement of the switching element or the pixel electrode. That is, the voltage is distributed in a predetermined two-dimensional pattern on the surface of the test object 50. At this time, when the conductive layer 211 of the modulator 200 is grounded or connected to a voltage source of an arbitrary level to form a reference voltage plane, the electric field is caused by the voltage difference between the surface of the object 50 and the conductive layer 211. This happens. The intensity distribution of the electric field at this time is proportional to the voltage distribution on the surface of the test object 50. Since the modulating layer 250 of the modulator 200 is placed in the electric field, the optical properties change according to the intensity of the electric field. The change in the optical properties of the electro-optic material is also proportional to the voltage distribution on the surface of the test object 50. When the inspection light passes through the modulator 200, the optical property of the passed inspection light is modulated as compared with the inspection light before passing, and this modulation is also proportional to the voltage distribution on the surface of the test object 50. The optical properties of the modulated layer 250 modulated herein refer to a polarization state, in particular ellipticity. When the modulation of the inspection light is detected by the modulation detection unit 300, which will be described later, the surface voltage distribution of the test object 50 can be immediately known, and as a result of the analysis, the normal operation of the test object 50 can be inspected. do.

The distance between the modulator 200 and the to-be-tested object 50 is so good that it is close. Since the modulator 200 is intended to change the ellipticity of the inspection light according to the change of the optical property proportional to the intensity of the electric field, an irregular flow such as floating matter, air, etc. present in the space between the modulator 200 and the inspected object 50. In order to minimize the change in the optical properties of the inspection light by the material, it is necessary to be disposed close to the test object 50 as possible. In addition, the farther the surface of the reference voltage plane and the inspected object 50 decreases the strength of the electric field formed by the same voltage difference, so that the change in the ellipticity of the test light is also weakened, and it becomes difficult to detect the modulation amount. It is also because. Furthermore, to prevent the electric field formed between the surface of the test object 50 and the conductive layer 211 of the modulator 200 from being cross-talked with the electric field formed between adjacent voltage sources on the test object 50. For this purpose, it is preferable that the distance between the modulator 200 and the inspected object 50 is kept at least below the distance between these voltage sources.

The modulator 200 may be manufactured in various forms, which will be described below with reference to FIG. 2A.

The upper glass plate 210 is made of a plate-like glass material.

The conductive layer 211 is formed over the entire lower surface of the upper glass plate 210. As described below, the conductive layer 211 is provided to provide a reference voltage plane for the voltage distribution formed on the surface of the object under test. The conductive layer 211 should be made of a conductive material and a material capable of transmitting light. Therefore, the conductive layer 211 is preferably formed of indium tin oxide (ITO). The conductive layer 211 may be formed by sputtering and directly forming indium tin oxide on the lower surface of the upper glass plate 210.

The lower glass plate 220 is also made of a plate-like glass material, spaced apart from the upper glass plate 210 at a predetermined interval. The space between the upper glass plate 210 and the lower glass plate 220 is a space where a modulation layer 250 to be described later will be formed, and a space between the two layers should be secured by the thickness of the modulation layer 250 required. In addition, the lower glass plate 220 is preferably disposed substantially parallel to the upper glass plate 210. This is to keep the thickness of the modulation layer 250 uniform, so that the length of the optical path is uniform even when light passes to any point of the modulation layer 250. The lower glass plate 220 should have a larger area than the upper glass plate 210. Therefore, as shown in FIG. 1, the edge of the lower glass plate 220 in cross section protrudes laterally based on the drawing than the edge of the upper glass plate 210.

In order to maintain a gap between the upper glass plate 210 and the lower glass plate 220, a spacer 270 may be inserted therebetween as necessary.

The sealing material 240 is disposed between the upper glass plate 210 and the lower glass plate 220, and close to each other to form a space partitioned from the outside. Sealing material 240 is preferably disposed along the edge of the lower surface of the upper glass plate (210). That is, the outer wall of the sealing material 240 is preferably disposed to be substantially in line with the side wall of the upper glass plate 210. This is to facilitate the application of the conductor 260, which will be described below, and the outer wall of the sealing material 240 is in line with the side of the upper glass plate 210, thereby substantially the outer end of the conductive layer 211 It is also on the same straight line.

An electron optical material is filled in the space formed by the sealing material 240 to form the modulation layer 250. Electro-optic material refers to a material whose optical properties change in an electric field that changes slowly relative to the frequency of light, that is, a material having an electro-optic effect.

Electro-optic material for forming the modulation layer 250 is a solid crystal, Potassium Dihydrogen Phosphate: KH ₂ PO ₄ (KDP), Potassium Dideuterium Phosphate: KD ₂ PO ₄ (DKDP), GaAs, BSO (Bismuth Silicon Oxide: Bi) ₁₂ SiO ₂₀ ), BGO (Bismuth Germanium Oxide: Bi ₁₂ GeO ₂₀ ) can be selected, but it is more preferably a liquid crystal (Liquid Crystal) material. The liquid crystal modulates the polarization state of light passing in the direction in which the electric field is formed, for example ellipticity, in proportion to the intensity of the electric field in the electric field. The modulation layer may be formed of a liquid crystal material having fluidity as described above, because the modulation layer 250 may be separated from the outside by the upper glass plate 210, the lower glass plate 220, and the sealing material 240. The choice of material of the modulation layer 250 can be widened. In particular, the liquid crystal material has the advantage that it is easy to secure because it is a material commonly used in LCD manufacturing.

The conductor 260 is applied from the side of the upper glass plate 210 to the outer wall of the sealing material 240. The conductor 260 can be formed simply by applying a conductive paste such as silver paste. As described above, when the outer wall of the sealing material 240 is aligned with the side surface of the upper glass plate 210, the formation of the conductor becomes easy. Since the conductive paste has plasticity, the conductor 260 is in close contact with the conductive layer 211 formed on the lower surface of the upper glass plate 210 in the process of applying the conductor 260 from the upper glass plate 210 to the sealing material 240. The conductor 260 is electrically connected to the conductive layer 211. Therefore, the conductor 260 can function as a connection terminal for electrically connecting the conductive layer 211 to the outside.

The modulator 200 brings the lower glass plate 220 closer to the object under test, and connects an external voltage source or a ground source to the conductive layer 211. When the operating power source is connected to the inspected object such as the TFT LCD, a two-dimensional voltage distribution is formed on the surface of the inspected object so as to correspond to the arrangement of the switching element and the pixel electrode. The electric field is formed between the voltage distribution on the surface of the test object and the voltage difference between the conductive layers 211. The electro-optic material filled in the modulation layer 250 changes in optical properties in proportion to the intensity of the electric field, and the light passing through the modulation layer 250 is modulated in the optical properties. Accordingly, when the light is emitted from the outside to pass through the modulation layer 250 and the optical characteristics of the modulated light are measured while passing through the modulation layer 250, the voltage distribution on the surface of the test object may be known.

In this process, since the lower glass plate 220 has a larger area than the upper glass plate 210, the lower glass plate 220 protrudes more laterally based on the drawings than the upper glass plate 210, and the conductor 260 is formed on the surface of the test object. It is obscured by the edge of the lower glass plate 220 with respect to. Therefore, the conductor 260 is blocked from directly contacting the surface of the inspected object.

2B is a cross-sectional view of another embodiment of a modulator 200. Only differences from the embodiment of the modulator shown in FIG. 2A will be described.

The lower glass plate 220 further includes an auxiliary conductive layer 221. The auxiliary conductive layer 221 may be formed on the upper edge of the lower glass plate 220, and may be formed by depositing ITO similarly to the conductive layer 211 of the upper glass plate 210.

The conductor 260 extends from the side of the upper glass plate 210 to the auxiliary conductive layer 221 of the lower glass plate 220 through the outer wall of the sealing material 240. As the auxiliary conductive layer 221 formed by depositing ITO on the lower glass plate 220 is in close contact with the conductor 260, the bonding force of the conductor 260 is strengthened, and a wider conductive surface can be obtained. The connection becomes easier. Since the auxiliary conductive layer 221 is formed on the upper surface of the lower glass plate 220, there is no problem of electrical contact with the test subject to be positioned below the lower glass plate 220.

In addition, the sealing material 240 is also preferably made of a conductive material. Since the sealing material 240 is in direct contact with the conductive layer 211 formed on the lower surface of the upper glass plate 210, the sealing material 240 may serve as an electrode for the conductive layer 211 if it is made of a conductive material.

When the conductor 260 is applied from the side of the upper glass plate 210 to the outer wall of the sealing material 240, if the sealing material 240 is a non-conductive material, the actual conductor 260 may conduct the upper glass plate 210. The area in contact with the layer 211 is very small in proportion to the thickness of the conductive layer 211. Therefore, the electrical connection between the conductor 260 and the conductive layer 211 may be unstable. However, if the sealing member 240 is made of a conductive material, it is possible to more stably maintain the electrical connection from the conductor 260 to the conductive layer 211. Further, when the sealing material 240 is made of a conductive material, it is preferable that the auxiliary conductive layer 221 of the lower glass plate 220 is in contact with the sealing material 240. At this time, since the auxiliary conductive layer 221 is electrically connected to the conductive layer 211 through the sealing material 240, especially when the conductor 260 is applied up to the auxiliary conductive layer 221, the conductor 260 To the conductive layer 211 of the upper glass plate 210 is kept very stable.

It is not necessary that the sealing material 240 is made of a conductive material and that the auxiliary conductive layer 221 is formed on the upper surface of the lower glass plate 220 at the same time. Can be. That is, even if only the sealing material 240 is made of a conductive material and the auxiliary conductive layer 221 of the lower glass plate 220 is not formed, the conductor 260 is in contact with the conductive layer 211 through the sealing material 240. Since the area can be more secured, the electrical connection to the outside can be maintained stably. In addition, even if the sealing material 240 is not a conductive material and the auxiliary conductive layer 221 is formed on the lower glass plate 220, the conductor 260 is formed if the conductor 260 extends to the auxiliary conductive layer 221. Since it is also attached to the lower glass plate 220 it is possible to obtain a stronger bonding force than at only the side of the upper glass plate 210 and the sealing material 240, and at the same time can secure a wider conductive surface exposed to the outside.

In the modulator 200 having such a configuration, inspection light enters from the lower glass plate 220 in the use state, is modulated while passing through the modulation layer 250, and passes through the upper glass plate 210.

The modulation detection unit 300 is for sensing the optical characteristics modulated along the cross section of the inspection light while passing through the modulator 200. While passing through the modulator 200, the inspection light changes optical characteristics such as phase and ellipticity. Since the change is proportional to the voltage distribution formed on the surface of the object 50, an optical phase detector is included. Any form can be used as long as the optical characteristics of the inspection light can be measured. However, preferably, a pair of polarization filters 310 and 320 and a camera 330 may be configured.

The pair of polarization filters 310 and 320 and the camera 330 constituting the modulation detection unit 300 are both disposed on the optical path of the inspection light. The first polarization filter 310 is located between the light source 100 and the test object 50, the second polarization filter 320 is behind the modulator 200, and the camera 330 is formed of the second polarization filter 320. It is arranged in the rear respectively. The first polarizing filter 310 may be disposed only in front of the modulator 200. However, as described above, since the distance between the modulator 200 and the inspected object 50 is very narrow, the first polarized filter 310 is located in front of the inspected object 50. It is preferable to arrange. The second polarization filter 320 may be disposed between the camera 330 and the modulator 200. That is, the first polarizing filter 310 and the second polarizing filter 320 may be disposed before and after the center of the modulator 200, respectively.

The inspection light emitted from the light source 100 is polarized while passing through the first polarization filter 310, and partially polarized, for example, an ellipticity, while being passed through the modulator 200 through the test object 50. If the polarization filter 320 is rotated at a predetermined angle with respect to the first polarization filter 310, some modulated inspection light may not pass through the second polarization filter 320. When this is stored as a two-dimensional image through the camera 330, the distribution of contrast shown in the two-dimensional image corresponds to the ellipticity of the inspection light. In this case, a phase retarder may be further disposed in front of the second polarization filter 320 so that the contrast ratio is further emphasized. As the phase retarder, one such as a quarter-wave plate can be used. The phase retarder causes the light output of the elliptically polarized inspection light to be modulated, thereby increasing the contrast ratio in the image obtained by the camera 330. The image acquired by the camera 330 may be analyzed according to a conventional image processing technique to finally grasp the voltage distribution formed on the surface of the object 50. Since the specific method of image processing belongs to a conventional technique, detailed description is omitted.

Meanwhile, in order to diffuse or concentrate the inspection light incident on the camera 330, the auxiliary optical lens group 500 as described above may be additionally disposed at the front end of the camera. The auxiliary optical lens group 500 has the same basic function as the optical lens group 400 for diffusing or concentrating the inspection light from the light source 100, except that the camera 330 focuses to acquire an image. There is more emphasis on functionality. Therefore, the auxiliary optical lens group 500 additionally disposed may further include a barrel and an autofocusing module for adjusting magnification and focus.

3 is an explanatory view showing another embodiment of a non-contact inspection apparatus according to the present invention. In the description of the present embodiment, in order to avoid duplication of description, the same description as the previous embodiment will be omitted and the same reference numerals will be used. Therefore, features that are not specifically described below are the same as those described in the foregoing embodiments.

The inspection table 600 is for supporting the inspected object 50 during the inspection process, and the inspected object 50 is horizontally placed on the upper surface. In addition, the through hole is formed in the vertical direction so that the light from the light source 100 can pass. The inspection table 600 is provided with a loading means (not shown) for loading the object 50 onto the inspection table 600 and a position correction means (not shown) for correcting the correct position of the object 50. . The loading means and the position correction means have a somewhat complicated mechanical configuration, and occupy a large space. Therefore, most of the moving parts are placed inside or below the inspection table so as not to be exposed on the inspection table. Since the mechanical configuration of the loading means and the position correction means is widely used not only in the flat display device manufacturing process but also in the semiconductor wafer manufacturing process, detailed description thereof will be omitted.

The horizontal support of the test target 600 to the test object 50 is related to the technical trend of the flat display device which is becoming larger. In other words, vertically supporting a large area flat display device is likely to be buckled because the main material of the flat display device is a glass plate, and when the flat display device is buckled, it is impossible to inspect a minute element on the surface thereof, or The reliability is lost. Furthermore, if the flat display device is kept vertical, the possibility of damage caused by external vibration increases.

The light source 100 and the first polarization filter 310 are disposed below the inspection table 600. Since the first polarization filter 310 is disposed below the second polarization filter 320 to be described below, it may be referred to as a lower polarization filter.

The modulator 200, the second polarization filter 320, and the camera 330 are sequentially disposed above the inspection table. Since the second polarization filter 320 is disposed above the first polarization filter 310, the second polarization filter 320 may be referred to as an upper polarization filter. In this case, the modulator 200, the upper polarization filter 320, and the camera 330 may be accommodated in one housing 700 so that the three components form one module. When the auxiliary optical lens group 400 is provided, the auxiliary optical lens group 400 may also be accommodated in the housing 700.

Since the modulator 200, the upper polarization filter 320, and the camera 330 are accommodated in one housing 700, the three components maintain the same relative arrangement simply by moving the housing 700 in a horizontal plane. It is possible to move relatively horizontally with respect to the subject 50 placed on the test stand 600.

The reason why the housing 700 should be horizontally moved is because the area to be inspected on the inspected object 50 is larger than the light transmission area of the modulator 200. This tendency is further increased as the large-area flat panel display becomes more common. As it becomes severe, in order to inspect all the inspection areas on the object 50, the modulator 200 and related components must be scanned within a horizontal plane. In this case, it is preferable that the light source 100 and the upper polarization filter 320 to inject the inspection light into the modulator 200 also operate on a horizontal plane while maintaining a relative position disposed on the same optical axis as the housing 700. That is, the housing 700, the light source 100, and the upper polarization filter 320 are relatively horizontally moved with respect to the inspected object 50 placed on the inspection table 600 while maintaining the relative position on the same optical axis. 50) Inspect all areas of inspection on the surface.

When the auxiliary optical lens group 400 is provided, the auxiliary optical lens group 400 includes a plurality of lenses and a plurality of lenses for optical magnification of an image to be acquired by the camera 330 or focus adjustment required for image acquisition. It may include a barrel for maintaining and adjusting the lens of the lens in a predetermined arrangement, and furthermore, an auto focusing module, so that its physical size is inevitably increased, and the driving device included in the barrel and the autofocus module is included. Are complicated. Since the auxiliary optical lens group 400 may be disposed above the inspection table 600 together with the camera 330, there is a mechanical interference problem with the loading means or the position correction means as compared to those disposed below the inspection table 600. Significantly reduced.

In addition, the optical lens group 400 disposed below the inspection table 600 does not require a complicated mechanism as compared to the auxiliary optical lens group 400, and may make the physical size thereof small. Therefore, even if both the light source 100 and the optical lens group 400, in addition to the lower polarization filter 310 is disposed below the inspection table 600, there is no problem of mechanical interference with the loading means or the position correction means.

Hereinafter, a preferred embodiment of the non-contact inspection method according to the present invention will be described in detail.

4 is a flowchart of one embodiment of a non-contact inspection method according to the present invention.

In order to proceed with the inspection, first, the object to be inspected, which is a flat display device, is placed horizontally on the examination table (S100). The reason for placing the subject horizontally on the examination table is as described above.

The test object is connected to an external power source to make the same condition as the actual operating state (S200).

On the other hand, the modulator is disposed close to the upper surface of the object under test (S300). The modulator is made of an electro-optic material whose optical properties change with the strength of an electric field, and a conductive layer is formed on one side thereof. The modulator is arranged so that the side with the conductive layer is far from the object under test.

In this state, a reference voltage is applied to the conductive layer of the modulator (S400). The reference voltage is for the electric field to be formed between the conductive layer and the surface of the test object in preparation for the voltage distribution to be formed on the upper surface of the test object. Any voltage source may be connected to apply the reference voltage, but it is preferable to ground it.

Next, the light is irradiated upward from below the test subject (S500). The irradiated light penetrates the inspected object and reaches the modulator. The modulator passes through the electro-optical material in the order of the conductive layer. Since the optical characteristics of the electro-optic material change in proportion to the intensity of the electric field formed between the conductive layer and the upper surface of the object under test, the light passing through the modulator is also changed. Is modulated. The light can be referred to as the inspection light because the light can be inspected as a result of the inspection.

The optical characteristics of the modulated light, that is, the inspection light, are measured (S600). At this time, the optical characteristic of the modulated inspection light is proportional to the two-dimensional distribution of the voltage formed on the upper surface of the inspected object. Therefore, when the modulation of the inspected light is distributed in two dimensions, it is possible to know the voltage distribution of the upper surface of the inspected object. have.

In order to easily measure the optical characteristics of the modulated inspection light, the step of measuring the optical characteristics of the modulated inspection light (S600), the first polarization before the inspection light irradiated from below the test object enters the modulator 610, second polarizing the inspection light passing through the modulator, and obtaining a two-dimensional image by the second polarized inspection light with the camera (S630). In the second polarization steps S610 and S620, a part of the modulated inspection light may be masked by adjusting the angle of each polarization. Therefore, the optical characteristics of the modulated inspection light appear as differences in contrast in the image obtained by the camera. As such, by acquiring an image in which the optical characteristic of the inspection light is represented by the difference in contrast (S630), the voltage distribution of the upper surface of the inspected object may be known through normal image processing.

After acquiring the image (S630), it is determined whether an inspection is required for another area on the object (S700), and if necessary, the light source and the camera of the inspection light are moved horizontally with respect to the object (S800). After the movement is completed, if the process proceeds from the step (S500) of irradiating the inspection light to the object again, the inspection can be performed in the same manner for other areas on the subject.

An embodiment of the present invention described above and illustrated in the drawings should not be construed as limiting the technical idea of the present invention. The scope of protection of the present invention is limited only by the matters described in the claims, and those skilled in the art will be able to modify the technical idea of the present invention in various forms. Accordingly, such improvements and modifications will fall within the scope of the present invention as long as they are obvious to those skilled in the art.

As described above, in the non-contact inspection apparatus according to the present invention, both a modulator and a means for sensing the optical characteristics of the inspection light modulated through the non-contact inspection apparatus are disposed on one side of the inspected object. That is, since the modulation detection unit and the modulator, which need to have a complicated structure and a moving path, can be arranged on one side of the object under test, and a light source having a simple structure can be arranged on the other side of the test object, However, the modulation detection unit and the modulator may be arranged together at a position where no spatial interference with the position correction means occurs. In addition, the modulation detection unit and the modulator are accommodated in a single housing so that the module can be modularized to facilitate relative movement with respect to the inspected object.

In the non-contact inspection apparatus according to the present invention, since the lower glass plate protrudes to the side, the external connection terminal of the modulator can block the electrical connection with the inspected object. In addition, since the space in which the modulation layer between the upper glass plate, the lower glass plate, and the sealing material is to be formed can be isolated from the outside, a flowable electro-optical material such as liquid crystal can be used.

In addition, the non-contact inspection method according to the present invention can be efficiently performed even with a modulator having a relatively small light transmission area for a large area flat display device.

Claims (24)

A light source arranged to be spaced apart from one surface of the inspected object, which is a flat display device, and emitting light to pass through the inspected object; A modulator disposed on the optical path of the light emitted from the light source and spaced apart from the other surface of the object, and modulating an optical property of the light in proportion to a voltage distribution on the surface of the object; And a modulation sensing unit for sensing a modulated optical characteristic of the light passing through the modulator, wherein the modulator includes an upper glass plate, a conductive layer coated on the entire lower surface of the upper glass plate, and a lower portion of the upper glass plate. A lower glass plate disposed to be spaced apart from each other and having a larger area than the upper glass plate; For a flat panel display device comprising a modulation layer made of an electro-optic material filled in a space partitioned by the upper glass plate, the lower glass plate, and a sealing material, and a conductor continuously applied from the side of the upper glass plate to the side of the sealing material. Non-contact inspection device. The method of claim 1, And a group of optical lenses for diffusing or concentrating light radiated from the light source to the object under test. delete The method of claim 1, And the sealing material is made of a conductive material and is disposed along an edge of a lower surface of the upper glass plate. The method of claim 1, The lower glass plate further includes an auxiliary conductive layer coated on the edge of the upper surface, The conductor is a non-contact inspection device for a flat panel display device is applied to the auxiliary conductive layer of the lower glass plate. The method of claim 5, The sealing material is made of a conductive material, And the auxiliary conductive layer of the lower glass plate is in contact with the sealing material. The method of claim 1, And a spacer inserted to maintain a gap between the upper and lower glass plates. The method of claim 1, wherein the modulation layer, Non-contact inspection device for flat panel displays made of liquid crystal material. The method of claim 1, wherein the modulation detection unit, A first polarizing filter disposed in front of the modulator on the optical path; A second polarization filter disposed behind the modulator; And a camera disposed behind the second polarization filter. The method of claim 9, wherein the modulation detection unit, And a phase delay unit disposed immediately before the second polarization filter. 11. The method according to claim 9 or 10, And an auxiliary optical lens group disposed between the camera and the second polarization filter to diffuse or concentrate the light incident on the camera. An inspection table on which a subject to be a flat display device is placed horizontally; A light source installed below the inspection table and emitting light to pass through the object under test; A lower polarization filter disposed above the light source and polarizing light from the light source; A modulator disposed above the test object on an axis of light emitted from the light source, and having an ellipticity that changes in proportion to the voltage distribution on the surface of the test object; An upper polarization filter installed above the modulator and polarizing light passing through the modulator; And a camera for acquiring a planar image by the light passing through the upper polarization filter, wherein the modulator includes an upper glass plate, a conductive layer coated on the entire lower surface of the upper glass plate, and a lower portion of the upper glass plate. A lower glass plate disposed to be spaced apart from each other and having a larger area than the upper glass plate; For a flat panel display device comprising a modulation layer made of an electro-optic material filled in a space partitioned by the upper glass plate, the lower glass plate, and a sealing material, and a conductor continuously applied from the side of the upper glass plate to the side of the sealing material. Non-contact inspection device. The method of claim 12, Further comprising a housing in which the modulator, the upper polarizing filter and the camera is installed therein, And the housing, the light source and the lower polarizing filter move horizontally with respect to the inspection table while maintaining a relative arrangement on the same optical axis. The method of claim 12, And a group of optical lenses for diffusing or concentrating light emitted from the light source to the object under test. The method of claim 12, And an auxiliary optical lens group disposed between the camera and the upper polarization filter to diffuse or concentrate the light incident on the camera. delete The method of claim 12, And the sealing material is made of a conductive material and is disposed along an edge of a lower surface of the upper glass plate. The method of claim 12, The lower glass plate further includes an auxiliary conductive layer coated on the edge of the upper surface, The conductor is a non-contact inspection device for a flat panel display device is applied to the auxiliary conductive layer of the lower glass plate. 19. The method of claim 18, The sealing material is made of a conductive material, And the auxiliary conductive layer of the lower glass plate is in contact with the sealing material. The method of claim 12, And a spacer inserted to maintain a gap between the upper and lower glass plates. The method of claim 12, wherein the modulation layer, Non-contact inspection device for flat panel displays made of liquid crystal material. delete delete delete

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