JP2008002944A - Conveyance inspection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To convey a flat inspection object, while keeping flat state, and to accurately detect defect. <P>SOLUTION: When voltages, having mutually reverse polarities, are applied to a pair of electrodes 7, 8 of a base member 5, Coulomb force is induced between the electrodes 7, 8 and the inspection object 1. The flat inspection object 1 is held at a prescribed interval by the base member 5, and the inspection object 1 is conveyed by a truck 14, while keeping the flat state. A light-emitting part 15 irradiates the surface of the inspection object 1 with laser light, while scanning is carried out in the width direction. A light-receiving part 16, extending in the width direction, receives reflected light from the surface of the inspection object 1. An inspection control part 17 discriminates defects on the surface of the inspection object 1, based on the detected signal from the light-receiving part 16. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a conveyance inspection system that detects a flaw on the surface or an internal pinhole while conveying a flat inspection object.

  Flat members such as glass substrates and films used in solar cells and liquid crystal displays are inspected for the presence of scratches on the surface, the presence or absence of internal defects, and the like. And when conveying such a flat member, you have to convey, without giving a stress and not damaging the surface. As such a member conveying device, there is one that conveys while holding a flat member in a non-contact state by utilizing electrostatic adsorption.

Here, if the inspection of the flat member is performed at the same time using this transport time, the manufacturing efficiency can be improved. A conveyance inspection system that simultaneously performs conveyance and inspection is disclosed in Patent Document 1. As a conveying device, a Coulomb force is generated between the object to be inspected and the electrode, the object to be inspected is held in a non-contact state, and the object to be inspected is conveyed by a belt conveyor or the like. As an inspection device, a camera and an illumination device are used, and an inspection object is imaged and inspected during transportation.
JP 2004-251723 A

  In the conveyance inspection system described above, an electrode base including an electrode unit and a camera are arranged opposite to each other with an object to be inspected interposed therebetween. The electrode base is provided with a notch having no electrode unit, and a camera is disposed facing the notch. Thus, the electrode unit is prevented from being reflected in the image captured by the camera.

  Here, when a notch exists in the electrode base in which the electrode units are uniformly arranged, the Coulomb force generated between the electrode and the object to be inspected is not uniform in the plane. Therefore, a partial stress is applied to the flat inspection object, and a part of the inspection object is bent. When detecting defects such as fine scratches on the object to be inspected, the illumination light is not reflected toward the camera or shadows are formed, making it impossible to detect fine defects. In particular, when the object to be inspected is a thin member such as a film, the influence of the unevenness of the object to be inspected is large, and the defect detection accuracy is lowered.

  Thus, in order to inspect while transporting a flat inspection object, it is necessary to maintain the inspection object in a flat state. Therefore, in view of the above, the present invention has an object to provide a transport inspection system capable of transporting a flat inspection object while maintaining a flat state by electrostatic attraction and improving the detection accuracy of defects. To do.

  The present invention includes a transport device that transports a flat inspection object while holding it by electrostatic attraction, and an inspection device that inspects the surface or the inside of the inspection object, and the inspection object held in a flat state is provided. A transport inspection system for inspecting while transporting, wherein the inspection device irradiates light on the surface of an object to be inspected, and emits light in a width direction perpendicular to the transport direction, and extends in the width direction. And a light receiving unit that receives light hitting the surface of the inspection object.

  A flat inspection object is conveyed while being maintained in a flat state. If light is emitted from the light emitting unit to the surface of the object to be inspected during this conveyance, the surface of the object to be inspected is not uneven, so that the light reflected by the surface or the light scattered by the defect is surely received by the light receiving unit. To reach. Therefore, if the inspection object has a defect, it can be reliably detected. And the light irradiated from the light emission part is scanned in the width direction of the to-be-inspected to-be-inspected object. The entire surface of the inspection object is exposed to light, and the inspection object can be inspected without any problem.

  Specifically, the transport device includes a flat base member that holds the inspection object in a non-contact state, and a base member that holds the inspection object or a moving unit that moves the inspection object. It has a pair of electrodes to which voltages having opposite polarities are applied. Each electrode is alternately and regularly arranged throughout the base member. By applying a voltage of opposite polarity to each electrode, a Coulomb force is induced between the electrode and the object to be inspected. Since the distribution of the electrodes is uniform, the Coulomb force is generated uniformly, and the inspection object is attracted to the base member at a predetermined interval by the Coulomb force. As a result, the flat test object is held in a flat state.

  The light receiving unit is disposed on the same side as the light emitting unit with respect to the object to be inspected, and receives light reflected by the surface of the object to be inspected. If there is a defect on the surface of the object to be inspected, the light hitting the defect is scattered. When there is no defect, the light hitting the surface of the inspection object is reflected as it is. Thus, the form of the light reflected on the surface of the inspection object varies depending on the presence or absence of defects. Based on the form of the reflected light received by the light receiving unit, the inspection apparatus can detect the presence or absence of defects on the surface of the inspection object.

  The light receiving unit is disposed on the opposite side of the light emitting unit with the object to be inspected therebetween, and receives light transmitted through the object to be inspected. In this case, the moving unit moves the base member holding the object to be inspected. With such an arrangement, it is possible to detect an internal defect of the inspection object. When there is no internal defect, the light hitting the inspection object passes through the inspection object as it is. When there is an internal defect, the light is scattered and the amount of transmitted light is reduced. Therefore, the inspection apparatus can detect an internal defect of the inspection object. Also, surface defects can be detected in the same manner.

  When the light receiving unit is disposed on the opposite side of the light emitting unit with the object to be inspected therebetween, it is on the same side as the base member. The base members are arranged in the transport direction, and the light receiving unit is disposed between adjacent base members. The position where the light emitted from the light emitting unit strikes and the position of the light receiving unit are shifted in the transport direction. Therefore, at the position where the inspection object is inspected, the inspection object is electrostatically attracted to the base member and held in a flat state.

  According to the present invention, the object to be inspected is irradiated with light, the light reflected by the object to be inspected or the light transmitted through the object to be detected is inspected for the presence of defects. By carrying the sample while maintaining a stable state, irregular reflection due to irregularities on the surface of the object to be inspected cannot occur, and a defect can be detected with high accuracy.

  The conveyance inspection system of this invention is shown in FIGS. This conveyance inspection system inspects a flat inspection object such as a glass substrate, a film, or a sheet while conveying it. The inspected object 1 is a material constituting a flat panel display, a solar cell, and the like, and is transported between processes in manufacturing, processing, and assembly. An inspection for inspecting the surface of the inspection object 1 and the conveying apparatus 2 for conveying the inspection object 1 while holding the inspection object 1 in a flat state by electrostatic adsorption in order to inspect the moving inspection object 1 during the conveyance. The apparatus 3 and the control apparatus 4 which drive-controls the conveying apparatus 2 and the test | inspection apparatus 3 are provided.

  The transport apparatus 2 includes a flat base member 5 that holds the inspection object 1 in a non-contact state, and a moving unit 6 that moves the inspection object 1. The base member 5 is placed vertically and conveys the inspection object 1 in a vertical state. The base member 5 may be placed horizontally, and in this case, the inspection object 1 is conveyed in a horizontal state.

  The base member 5 has a pair of electrodes 7 and 8 to which voltages having opposite polarities are applied, and the voltage applied to the electrodes 7 and 8 is controlled by the voltage controller 9. As shown in FIG. 4, the pair of electrodes 7 and 8 are arranged with the insulating plate 10 therebetween, and the periphery is surrounded by the insulating plate 11 to form the electrode unit 12. The areas of the electrodes 7 and 8 are equal.

  The electrode unit 12 has a fixed shape such as a square or a circle. The plurality of electrode units 12 are regularly and flush with one surface of the base member 5, and the electrode unit 12 and the inspection object 1 face each other. Further, the electrode unit 12 is provided with a proximity switch 13 to detect the distance between the electrodes 7 and 8 and the object 1 to be inspected.

  The voltage control unit 9 applies a reverse polarity voltage to the electrodes 7 and 8 of each electrode unit 12. As a result, dielectric polarization occurs on the surface of the inspection object 1 facing the electrodes 7 and 8, and a Coulomb force is induced between the inspection object 1 and the electrodes 7 and 8. 5 is electrostatically adsorbed. Based on the output of the proximity switch 13, the voltage control unit 9 performs control to turn on and off the applied voltage according to the distance between the electrodes 7 and 8 and the inspection object 1, and keeps the distance constant.

  The moving unit 6 moves the carriage 14 that supports one end of the inspection object 1, here the lower end. The carriage 14 is reciprocated by a motor or cylinder as the moving unit 6 and moves in parallel with the base member 5 at a constant speed. A belt conveyor may be used instead of the carriage 14.

  In the transport device 2 described above, the inspection object 1 is cantilevered and transported linearly. During the conveyance in this state, the voltage applied to the electrodes 7 and 8 is controlled, so that the distance between the electrodes 7 and 8 and the inspection object 1 is kept constant. Accordingly, the flat inspection object 1 can be transported with a predetermined distance from the base member 5 while maintaining a flat state.

  The inspection apparatus 3 drives and controls the light emitting unit 15 that irradiates the inspection object 1 with light, the light receiving unit 16 that receives the light that hits the inspection object 1, and the light emitting unit 15 and the light receiving unit 16 to detect defects. And an inspection control unit 17 that performs detection.

  The light emitting unit 15 and the light receiving unit 16 are arranged on the same side facing the inspection object 1, and the light emitting unit 15 is arranged on the upstream side in the transport direction with respect to the light receiving unit 16. The light emitting unit 15 irradiates the inspection object 1 with laser light. The laser light strikes the surface of the inspection object 1 at a predetermined incident angle, and the light receiving unit 16 receives the laser light reflected by the surface of the inspection object 1.

  In the light emitting unit 15, as shown in FIG. 5, a laser oscillator 20, a beam expander 21, reflection mirrors 22a, 22b, and 22c, a polygon mirror 23, and a collimator are mounted on a substrate 19 mounted in a casing 18. A lens 24, an fθ lens 25, a reflection mirror 26, a synchronization detection sensor 27, and reflection mirrors 28 and 29 are arranged. The laser oscillator 20 generates a short wavelength semiconductor laser. The beam expander 21 sets the laser beam diameter. The laser light from the laser oscillator 20 is bent by the reflection mirrors 22a, 22b, and 22c and then deflected by the polygon mirror 23. That is, as the polygon mirror 23 rotates, the reflection direction of the laser light changes in a fan shape, and the surface of the inspection object 1 is scanned.

  The synchronization detection sensor 27 detects the boundary of the scanning range of the laser beam, and is used to synchronize the scanning of the laser beam and the detection of the reflected light. The collimator lens 24 and the fθ lens 25 scan the reflected light having a uniform angular velocity deflected by the polygon mirror 23 on the surface 2 of the inspection object at a uniform velocity. The collimator lens 24 converts the reflected light from the polygon mirror 23 into parallel light. The fθ lens 25 condenses the laser light so that the irradiation position is linear on the surface of the inspection object 1. The fθ lens 25 condenses the laser beam also in the direction (sub-scanning direction) perpendicular to the direction (main scanning direction) in which the laser beam is scanned by the polygon mirror 23. The laser light emitted from the fθ lens 25 is reflected by the reflection mirror 28, passes through the opening 30 of the substrate 19, is reflected by the reflection mirror 29 fixed to the lower surface of the substrate 19, and is emitted from the opening of the casing 18.

  On the lower surface of the substrate 19, a motor, a driver circuit for driving the motor for rotating the polygon mirror 23, and a driver circuit for driving the laser oscillator 20 and the synchronization detection sensor 27 are arranged. These driver circuits are controlled by the inspection control unit 17.

  In the light receiving unit 16, as shown in FIG. 6, a rod-shaped light guide 33 is accommodated in a cylindrical holder 32, and a photomultiplier tube (photomultiplier) 34, which is a photodetector, is provided on one end side of the light guide 33. Is arranged. The photo 34 may be provided at both ends of the light guide 33.

  A slit 35 is formed in the holder 32 along the axial direction. The ride guide 33 faces the outside from the slit 35, and the reflected light from the surface of the inspection object 1 enters the light guide 33 through the slit 35.

  The light guide 33 is a rod-shaped optical element in which a light receiving surface 33i and a scattering surface 33a facing each other extend in parallel in the axial direction. The light guide 33 is an optical element having translucency using, for example, an acrylic resin, and the matte treatment is applied only to the scattering surface 33a or a scattering sheet is attached. The light guide 33 is disposed in the holder 32 so that the light receiving surface 33 i faces the slit 35. The reflected light that has passed through the slit 35 enters from the light receiving surface 33i and is reflected by the scattering surface 33a.

  When the photomar 34 detects the light emitted from the end face of the light guide 33, the photomar 34 outputs a detection signal. The output level of this detection signal changes according to the amount of received light.

  Here, the light emitting unit 15 is positioned so that the scanning direction of the laser light emitted from the light emitting unit 15 is the width direction orthogonal to the transport direction. Accordingly, the light receiving unit 16 is positioned so that the slit 35 of the light receiving unit 16 is parallel to the width direction of the inspection object 1. Then, the distance between the light emitting unit 15 and the inspection object 1 is determined so that the scanning range of the laser light is equal to or larger than the width of the inspection object 1. Further, the incident angle of the laser beam is set according to the inspection object 1, and the inclination angle of the light emitting unit 15 with respect to the inspection object 1 is determined. The light receiving unit 16 is located on the optical path of the reflected light so that the light reflected by the surface of the inspection object 1 can be received.

  The inspection control unit 17 controls the operations of the light emitting unit 15 and the light receiving unit 16 so that the scanning position of the laser beam and the output of the photo 34 are synchronized. And while detecting a defect based on the detection signal from the photo 34 of the light-receiving part 16, the timing signal when the light emission part 15 generate | occur | produces a laser beam, and the positional information on the to-be-inspected object 1 output from the moving part 6 Based on this, the position of this defect is calculated.

  The control device 4 comprehensively controls the moving unit 6, the voltage control unit 9, and the inspection control unit 17. That is, the inspection is performed in synchronization with the conveyance timing of the inspection object 1 and the inspection timing, and the inspection result is output by display or printing.

  Next, the operation of the conveyance inspection system will be described. The conveyance device 2 conveys the inspection object 1 at a constant speed while maintaining the non-contact state of the inspection object 1 with respect to the base member 5 at predetermined intervals by electrostatic adsorption. Then, laser light is emitted from the light emitting unit 15 to the surface of the inspection object 1. The laser beam is scanned in the width direction of the moving inspection object 1 and reflected by the surface of the inspection object 1. Since the scanning speed is higher than the moving speed of the inspection object 1, the entire surface of the inspection object 1 can be scanned.

  Reflected light from the surface of the inspection object 1 reaches the light receiving unit 16 and enters the ride guide 33 through the slit 35. The incident light is reflected in various directions by the scattering surface 33 a of the light guide 33. The scattered light reflected in various directions by the scattering surface 33a is reflected inside the light guide 33 and emitted from the end surface, and the photo 34 receives the light. The detection signal photoelectrically converted by the photo 34 is sent to the inspection control unit 17. The inspection control unit 17 compares the output value obtained by processing the detection signal from the photo 34 with the reference value, and determines whether there is a defect on the surface of the inspection object 1.

  For example, when the inspection object 1 has a defect, the laser light is scattered by the defect, the reflected light received by the light receiving unit 16 becomes weak, and the output value of the detection signal is lower than when there is no defect. Thereby, the presence or absence of a defect is known. The output waveform of the detection signal varies depending on the type of defect. The output waveform of the detection signal is compared with the reference waveform for each defect type to determine the defect type. When there is a defect, the position of the defect in the inspection object 1 is specified based on the scanning position of the laser beam at that time and the position information of the inspection object 1.

  Thus, since the flat inspection object 1 can be conveyed while maintaining a flat state, reflected light from the surface of the inspection object 1 can be accurately detected, and minute defects can be detected. It becomes. For example, when the inspection object 1 is a glass substrate, it is possible to detect internal defects such as surface scratches, bubbles, and cracks. In the case of a sheet or film, it is possible to detect scratches, adhesion of foreign matter, and pinholes. Furthermore, since the density of the surface can be detected, it is possible to detect light stains, omissions and unevenness when surface treatment is performed.

  The inspection apparatus 3 is a regular reflection system that detects reflected light, but as an inspection apparatus 3 of another form, as shown in FIG. 7, it is configured to detect irregular reflection even with the same reflected light. May be. That is, in the irregular reflection type inspection apparatus 3, the reflected light can be detected if the light receiving unit 16 is arranged on the optical path of the reflected light when the laser light from the light emitting unit 15 is reflected by the surface of the inspection object 1. The light receiving unit 16 is arranged closer to the light emitting unit 15 than the optical path. If there is a defect on the surface of the object to be inspected 1, the laser beam hits the defect and is irregularly reflected. The light receiving unit 16 receives the irregularly reflected light. Therefore, the light receiving unit 16 receives the irregularly reflected light when the surface of the inspection object 1 has a defect, and does not receive the light reflected by the surface of the inspection object 1 when there is no defect.

  As another type of inspection apparatus 3, there is a transmission method for detecting light transmitted through the inspection object 1. As shown in FIG. 8, the laser beam that has passed through the inspection object 1 is detected with respect to the inspection object 1 having translucency. The light receiving unit 16 is located on the opposite side of the light emitting unit 15 with the inspection object 1 interposed therebetween. That is, the light receiving unit 16 is positioned on the optical path of the laser light irradiated from the light emitting unit 15 and transmitted through the inspection object 1. In the transport device 2, the plurality of base members 5 are arranged, and the light receiving unit 16 is disposed in a gap formed between two adjacent base members 5.

  The laser light emitted from the light emitting unit 15 is transmitted through the inspection object 1, and the light receiving unit 16 receives the transmitted light. If there is a defect inside or on the surface of the inspection object 1, the laser beam hits the defect and is scattered. At this time, the transmitted light becomes weaker than when there is no defect, and the presence or absence of the defect can be detected.

  In this case, the inspection object 1 cannot be electrostatically adsorbed in the gap between the two base members 5, but the scanning position of the laser beam is on the upstream side in the transport direction from the gap. In this scanning position, the inspection object 1 is electrostatically attracted and is kept flat. Therefore, when the inspection object 1 passes through the gap, a partial stress is applied to the inspection object 1. However, since the inspection point is on the upstream side of the clearance, it is not affected by the stress and is flat. The inspected object 1 in a state can be inspected with high accuracy.

  In addition, this invention is not limited to the said embodiment, Of course, many corrections and changes can be added to the said embodiment within the scope of the present invention. As the inspection apparatus, a light receiving unit may be arranged on both the same side and the opposite side of the object to be inspected, and detection of defects by transmission and detection of defects by reflection may be combined. As a result, the surface defect and the internal defect of the object to be inspected can be detected simultaneously, and the inspection efficiency can be increased.

  As a transport device, a base member that holds an object to be inspected in a non-contact state may be moved. The base member holds the object to be inspected while maintaining the flat state by electrostatic adsorption. The base member is moved along the guide by a motor, a cylinder, or the like. In this case, a reflection type or irregular reflection type inspection apparatus is used.

  Further, the base member may be a belt. By rotating the belt, the inspection object electrostatically attracted to the belt moves while maintaining a flat state. As another form of transfer device, a pair of electrodes are alternately arranged on the base member along the transfer direction. The voltage controller alternately switches the polarity of the voltage applied to each electrode. The inspection object is electrostatically attracted and moved by the force in the conveying direction component of the Coulomb force generated between the inspection object and the electrode. In the case of the above two conveying devices, the inspection device can be used in any manner.

The top view which shows schematic structure of the conveyance inspection system of this invention Front view showing schematic configuration of transport inspection system Control block diagram of conveyance inspection system Front view of electrode unit Light emitting unit internal configuration diagram Cross section of light receiving part Diagram showing diffuse reflection inspection system Diagram showing a transmission type inspection device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inspection object 2 Conveyance apparatus 3 Inspection apparatus 4 Control apparatus 5 Base member 6 Moving part 7, 8 Electrode 9 Voltage control part 12 Electrode unit 14 Carriage 15 Light emission part 16 Light reception part 17 Inspection control part

Claims (4)

It is equipped with a transport device that transports a flat inspection object while holding it by electrostatic attraction, and an inspection device that inspects the surface or the inside of the inspection object, and inspects while transporting the inspection object held in a flat state An inspection apparatus that irradiates light on the surface of an object to be inspected and scans the light in a width direction perpendicular to the transport direction; and a light emitting unit that extends in the width direction and inspects the object to be inspected. A conveyance inspection system comprising: a light receiving portion that receives light that has hit the surface. The transport device includes a flat base member that holds the inspection object in a non-contact state and a base member that holds the inspection object or a moving unit that moves the inspection object, and the base members have opposite polarities. A voltage is applied between the electrodes and the object to be inspected, and a Coulomb force is induced between the electrode and the object to be inspected. 2. The transport inspection system according to claim 1, wherein the transport inspection system is disposed on the same side as the light emitting unit with respect to the object to be inspected and receives light reflected by the surface of the object to be inspected. The transport device includes a flat base member that holds the object to be inspected in a non-contact state and a moving unit that moves the base member that holds the object to be inspected, and voltages having opposite polarities are applied to the base member. The Coulomb force is induced between the electrode and the inspection object, and the inspection object is attracted to the base member at a predetermined interval by the Coulomb force. The conveyance inspection system according to claim 1, wherein the conveyance inspection system is disposed on the opposite side of the light emitting unit with the light passing through the inspection object. The conveyance inspection system according to claim 3, wherein a plurality of base members are arranged in the conveyance direction, and a light receiving portion is disposed between adjacent base members.

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