JP2006267022A - Defect inspection device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a defect inspection device and method capable of detecting a defective part difficult to be detected in a prior art, irrespective of a shape and a directivity thereof. <P>SOLUTION: An inspected object 50 is irradiated with an irradiation light 111 with a fringe-like pattern 190, and a defect pattern 195 appeared in response to the defective part of the inspected object is detected from the fringe-like pattern transmitted through the inspected object. A position of the fringe-like pattern emitted to the inspected object is changed therein to detect the defective part, irrespective of the shape and the directivity of the defective part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a defect inspection apparatus and method for detecting defects by image measurement of transmitted light with respect to an object having transparency such as glass, a resin body, a thin ceramic material, and a liquid. The present invention relates to a defect inspection apparatus and method that can detect defects such as surface irregularities, cracks, internal bubbles, and density of light transmittance regardless of the shape and direction.

  Conventionally, as a method for detecting uneven defects on the surface of an inspection object made of a light-transmitting material, as shown in FIG. 24, a light source 2 and an imaging element are opposed to the inspection surface 1 a of the inspection object 1. In general, a method for detecting the defect based on a reflected light image obtained by the image pickup device 3 by projecting the light source 3 and projecting the light from the light source 2 and reflecting the light from the inspection surface 1a is performed (for example, , See Patent Document 1).

In addition, as another method for detecting uneven defects on the surface of the inspection object made of a light-transmitting material, as shown in FIG. 25, the inspection object 1 is sandwiched between the imaging elements on the inspection surface 1a side. There is also a method in which 3 is arranged, the light source 2 is arranged on the non-inspection surface 1b side, and an image made of light transmitted through the inspection object 1 is picked up by the image pickup device 3 (for example, see Patent Document 2).
JP 2004-226160 A JP 2001-41719 A

In the inspection method using the reflected light, when the defect portion has poor characteristics, there is a problem that a marked difference does not occur between the defect portion and the non-defect portion, and it is difficult to distinguish between the two.
In the case of an inspection method using reflected light, generally, the inspection surface 1a is often smooth and hardly causes diffuse reflection, so that an image can be obtained by receiving specular reflection light. Therefore, in order to inspect the slight undulation of the inspection surface 1a or the inspection surface 1a formed of a curved surface, a light source that emits light from multiple directions is required, such as a dome-type illumination device. On the other hand, when such a light source is used, a defect portion to be detected is also irradiated with light from multiple directions, so that specular reflection light is also incident on the image sensor 3. Therefore, as a result, it becomes difficult to distinguish between a defective part and a non-defective part.
Further, because of the detection principle of using the surface reflected light, it is not possible to detect cracks inside the inspection object 1 and the density of the transmittance.

  Further, in the inspection method using transmitted light, when a uniform solid color light source is used as the light source for transmitted illumination over the entire field of view of the image pickup device 3, the uneven defect portion present on the inspection surface 1a having a gently curved surface. In addition, it is difficult to detect a defective portion such as a crack having a smooth cracked cross section. This is because the defect part is uniformly irradiated with light from a wide range, so that even if light refraction or reflection occurs due to the defect part inside the inspection object 1, the feature of the defect part is poor. It is considered that the cause is that an image of a defective portion is sometimes buried in the background light source 2 and is difficult to be captured as a defective portion image.

  The present invention has been made to solve such problems, and it is an object of the present invention to provide a defect inspection apparatus and method capable of detecting a defective portion that has been difficult to detect in the conventional defect inspection using transmitted light. And

In order to achieve the above object, the present invention is configured as follows.
That is, according to the defect inspection apparatus in the first aspect of the present invention, in the defect inspection apparatus that detects a defective portion of the inspection object based on the transmitted light that has passed through the inspection object having transparency,
An irradiation device for irradiating the inspection object with irradiation light having a striped pattern;
An imaging device for imaging the striped pattern that has passed through the inspection object;
A detection device connected to the imaging device and detecting a defect pattern appearing in accordance with the defect portion from the striped pattern;
It is provided with.

  You may comprise the said irradiation apparatus so that it may have a light source and the pattern formation apparatus which is provided between the said light source and the said to-be-inspected object, and forms the said striped pattern.

  The pattern forming apparatus is configured to include a light shielding member that forms the striped pattern and a projection position changing device that moves the light shielding member to change the irradiation position of the striped pattern on the inspection object. May be.

  The light shielding member has two mask plates each formed with a slit, and the projection position changing device is configured to further change the shape of the striped pattern by relatively moving the mask plate. May be.

  The striped pattern is a pattern in which dark portions having a width W1 and bright portions having a width W2 are alternately arranged. When d is the size of the minimum defective portion to be detected, d ≧ You may comprise so that the control apparatus which performs the operation control which moves the said light-shielding member to the position which satisfy | fills the relationship of (W1 + W2) with respect to the said projection position change apparatus may be provided.

  Here, the movement of the light shielding member corresponds to the movement of the light shielding member for changing the width dimensions W1 and W2 in the dark part and the bright part in the striped pattern.

  When the striped pattern has the dark part and the bright part having a relationship of d <(W1 + W2), the control device controls the operation of the projection position changing device to move the light shielding member, and the imaging You may comprise so that an apparatus may image the said striped pattern which passed the said to-be-inspected object for every movement of the said light-shielding member.

  Here, the movement of the light shielding member refers to the movement of the light shielding member for changing the width dimensions W1 and W2 in the dark part and the bright part in the striped pattern, and the width dimensions W1 and W2. This corresponds to at least one of the movement of the light shielding member in the width direction of the dark part and the bright part.

  The irradiation device may be configured by a display device that displays the striped pattern on a display surface and irradiates the displayed striped pattern onto the inspection object.

  The irradiation device may include a light source and a pattern member that displays the striped pattern and reflects light from the light source as the irradiation light to irradiate the inspection object.

  The irradiation device may include a light source and further include a moving device that relatively moves the object to be inspected and the imaging device.

  The inspection object is a fluid, and the irradiation device is a storage container for storing a light source and a fluid-like inspection object, and is located between the light source and the inspection object and the striped pattern You may comprise so that it may have a storage container which has the pattern formation part which formed.

  The irradiation apparatus may be configured to irradiate the inspection object with the irradiation light having a color different from that of the inspection object.

  The imaging device may be configured with a scanner.

Further, according to the defect inspection method in the second aspect of the present invention, in the defect inspection method for detecting a defective portion of the inspection object based on the transmitted light that has passed through the inspection object having transparency,
Irradiate the inspection object with irradiation light consisting of a striped first pattern,
Irradiating the object to be inspected with irradiation light composed of a second pattern having a stripe shape different from the first pattern,
Imaging the first striped pattern and the second striped pattern that have passed through the inspection object,
Detecting a defect pattern that appears in accordance with the defect from at least one of the first stripe pattern and the second stripe pattern;
It is characterized by that.

  In the second aspect, each of the first and second striped patterns is a pattern in which a dark portion having a width W1 and a bright portion having a width W2 are alternately arranged, and is a minimum to be detected. Where d is a size satisfying the relationship of d ≧ (W1 + W2), and the first and second striped patterns have a relationship of d <(W1 + W2). When the light portion is provided, the light shielding member for creating the first and second stripe patterns is moved, and each time the light shielding member is moved, the first and second stripes that have passed through the inspection object. An image of a pattern may be taken.

According to the defect inspection apparatus of the first aspect and the defect inspection method of the second aspect, since the inspection object is irradiated with the irradiation light of the striped pattern and the transmitted light passing through the inspection object is imaged, Correspondingly, a phenomenon occurs in which the shape of the striped pattern collapses and is no longer a constant pattern. Therefore,
It is possible to detect not only defects on the surface of the object to be inspected, but also cracks in the object to be inspected and density of transmittance. Furthermore, it is possible to easily detect a defective portion as compared with the case of irradiating the inspection object with uniform light of a single color. Therefore, it becomes possible to detect a defective portion that has been difficult to detect conventionally.

  Furthermore, by changing the striped pattern irradiated to the object to be inspected, it is possible to evaluate the defect portion whose position, size, refraction characteristics, etc. are unknown by giving various light source patterns with a single illumination device. In addition, despite the occurrence of a deformed portion in the striped pattern corresponding to the defective portion, the overlap with the normal striped pattern accidentally overlapped with the normal striped pattern, and the overlap was caused by the change in the striped pattern. It is possible to remove the defective portion. Further, by changing the striped pattern irradiated to the inspection object, it becomes possible to detect the defect portion regardless of the shape and directionality of the defect portion on the inspection object.

  Further, for example, by forming the irradiation device with a display device such as a liquid crystal display device or a cathode ray tube display device, the striped pattern can be easily formed and changed, and the object to be inspected can be easily irradiated. be able to.

  A defect inspection apparatus according to an embodiment of the present invention and a defect inspection method executed by the defect inspection apparatus will be described below with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected about the same component.

First, basic matters regarding the defect inspection apparatus of the present embodiment will be described.
The defect inspection apparatus according to the present embodiment is an inspection apparatus that detects a defect portion in the inspection object based on the transmitted light that has passed through the inspection object having transparency. Specifically, the irradiation light has a striped pattern. Is an inspection apparatus that detects a defective portion by irradiating the inspection object with an image and imaging a striped pattern that has passed through the inspection object.

  The inspection object is an object that is transparent or translucent to the irradiation light, or an object that is transparent or translucent to light having a wavelength that can be detected by the image pickup apparatus. Specifically, glass substrates for liquid crystals, liquid crystal filters, liquid crystal display front panels, optical lenses, optical disks, tablet packaging materials (PTP), blister packs, lamp covers, headlight lenses, continuous films, optical fibers, surfaces Permeable material coated with a film or film, incompatible liquid such as water and oil, and the like.

  Further, the defect portion in the inspected object is, for example, an arcuate recess 52a or a V-shaped flaw 52b existing on the surface 51 of the inspected object 50 as shown in FIGS. 10 and 11, and FIGS. Cracks 52c and voids 52d existing inside the inspection object 50 as shown in FIG. 14, coating unevenness 52e applied to the surface 51 of the inspection object as shown in FIG. Such bubbles, the different fluid 52f included in the fluid-like inspection object 50 as shown in FIG. In addition, these defect parts 52a-52f may be named generically, and the defect part 52 may be described.

  In addition to visible light, infrared light and ultraviolet light that allow a defect portion included in the inspection object to appear on the image can be used as the irradiation light. On the other hand, X-rays that pass through the defective portion included in the inspection object and do not appear on the image are not included. In the defect inspection apparatus 101 described below with reference to FIG. 1 and the like, the irradiation light is taken as an example of visible light.

  The striped pattern is a pattern formed by aggregating a plurality of lines having a certain width dimension, and is a pattern in which shading or hue is alternately different between adjacent lines. Specifically, for example, vertical stripe patterns 191a and horizontal stripe patterns 191b as shown in FIG. 16, concentric stripe patterns 192 as shown in FIG. 17, polygonal stripe patterns 193a to 193c as shown in FIG. It is the shape. In the following description, these striped patterns are collectively referred to by reference numeral 190. As the various striped patterns 190, a pattern to be used is appropriately selected corresponding to the inspection object 50. That is, the vertical stripe pattern 191a and the horizontal stripe pattern 191b are usually used. For example, a concentric stripe pattern 192 is used for a circular inspection object 50 such as an optical lens or an optical disk. For transparent molded products such as packs, electric lamp covers, and headlight lenses, for example, polygonal stripe patterns 193a to 193c are used corresponding to the shape of each molded product.

In the defect inspection apparatus of this embodiment, as will be described later, the defective portion 52 of the inspection object 50 is detected by imaging the striped pattern 190 that has passed through the inspection object 50. The basic detection principle will be described.
The detection principle uses refraction of light rays generated on the surface of the inspection object 50 or inside. Desirably, the light irradiated on the inspection object 50 from a light source that emits parallel light is refracted by the unevenness or crack surface of the surface of the inspection object 50, and is received by the imaging device at a position different from the original. By using a pattern illumination such as a slit pattern as the light source, the image receiving pattern on the imaging data is disturbed, and a defective portion can be detected. For example, when the light of the striped pattern 190 passes through the arc-shaped recess 52a existing on the surface 51 of the inspection object 50 illustrated in FIG. 10, the striped pattern 190 is formed as illustrated in FIG. Disturbances and defect patterns 195 occur. Further, a defect pattern 195 is generated as shown in FIG. 11B in accordance with the V-shaped scratch 52b existing on the surface 51 shown in FIG. Further, a defect pattern 195 is generated as shown in FIG. 12B in accordance with the crack 52c existing in the inspection object 50 shown in FIG. By detecting such a defect pattern 195 from the captured image, the defect portion 52 of the inspection object 50 is detected.

Next, the defect inspection apparatus of this embodiment will be specifically described below.
As shown in FIG. 1, the defect inspection apparatus 101 according to the present embodiment has, as a basic configuration, an irradiation apparatus 110 that irradiates the inspection object 50 with irradiation light 111 including the above-described striped pattern 190, and An imaging device 120 that images the striped pattern 190 that has passed through the inspection object 50, and a detection device 130 that is connected to the imaging device 120 and detects a defect pattern 195 that appears from the striped pattern 190 in accordance with the defect portion. Furthermore, a control device 180 that controls the operation of the irradiation device 110 based on the detection result of the detection device 130 is provided.
Here, as the distance between the irradiation apparatus 110 and the inspection object 50 is larger, the parallel light is obtained so that the light irradiated from the irradiation apparatus 110 to the inspection object 50 becomes more parallel light. However, it is preferable to arrange them at a distance of, for example, about 50 mm or more. Further, in order to support the inspection object 50, a transparent member or the like can be disposed between the irradiation apparatus 110 and the inspection object 50, or between the inspection object 50 and the imaging apparatus 120.
The defect inspection apparatus 101 configured as described above can be used as an apparatus for inspecting a protective cover of a mobile phone liquid crystal screen as an example.

As shown in FIGS. 2 and 3, the irradiation device 110 includes a light source 112 and a pattern forming device 113 that is provided between the light source 112 and the inspection object 50 and forms a striped pattern 190.
The light source 112 preferably has a configuration that generates parallel light, and includes, for example, an LED, a halogen, a fluorescent lamp, and the like, and a configuration of a flat light source as illustrated is preferable. Further, although the color of light generated from the light source 112 is generally white, when the inspection object 50 is a single-color transparent body, the defective portion is detected not by the density of the striped pattern 190 but by the hue change. It is preferable to use chromatic colors.

  The pattern forming device 113 includes a light shielding member 114 that forms the striped pattern 190 and a projection position changing device 115 that moves the light shielding member 114 to change the irradiation position of the striped pattern 190 on the inspection object 50. Here, the change of the irradiation position means that the irradiation position is changed by changing the width W1 and the gap W2 of the strip-shaped plate 1141, and all the strip-shaped plates 1141 are moved as a whole, as will be described below. For example, at least one of the change of the irradiation position by rotating is applicable. The light shielding member 114 is configured to be able to form various striped patterns 190 as exemplified with reference to FIGS. 16 to 18. 2 and 3 illustrate the case where the vertical stripe pattern 191a and the horizontal stripe pattern 191b as shown in FIG. 16 are formed. Further, as the light shielding member 114, a plurality of strip-shaped plates 1141 can be used as shown in FIG. 2, or a mask plate 1142 can be used as shown in FIG.

  When the strip-like plate 1141 is used, as shown in FIG. 4, the width W1 of the strip-like plate 1141 forms a dark portion, that is, a light-shielding portion of the striped pattern 190 shown in FIG. W2 forms a bright portion of the striped pattern 190, that is, a translucent portion. By adopting the strip-shaped plate 1141, there is an advantage that the parallelism of the light beam applied to the inspection object 50 can be limited to a certain range without using a parallel light source. The striped pattern 190 can be changed by changing the width W1 and the gap W2 of the strip-shaped plate 1141. In order to change the width W1, there are methods of exchanging the strip-shaped plate 1141 itself or changing the inclination angle of the strip-shaped plate 1141 with respect to the optical axis from the light source 112. As for the gap W2, for example, each strip-like plate 1141 can be connected by a connecting mechanism, and the connecting position can be driven by the projection position changing device 115 to widen each gap W2. It is possible to cause the coupling mechanism to change the inclination angle of the strip-shaped plate 1141. Further, the projection position changing device 115 may be configured to have a rotation mechanism that rotates all the strip-shaped plates 1141 connected to each other on a plane. With the rotation mechanism, the direction of the striped pattern 190 irradiated to the inspection object 50 can be changed, for example, from a vertical striped pattern 191a shown in FIG. 16 to a horizontal striped pattern 191b. For changing the orientation of the striped pattern 190, all the strip-shaped plates 1141 connected to each other may be rotated with respect to the fixed light source 112, or the light source 112 itself having the strip-shaped plates 1141 arranged in parallel may be rotated. You may comprise so that it may rotate with the strip shaped board 1141. FIG.

  Specific numerical values of the width W1 and the gap W2 and the dimensional relationship between the width W1 and the gap W2 and the defect portion 52 will be described later because they are related to the defect inspection method.

In this way, by changing the irradiation position of the striped pattern 190 on the inspection object 50, the defect pattern 195 corresponding to the defect portion 52 of the inspection object 50 is generated in spite of the occurrence of the defect pattern 195. The above-described overlap can be removed for the defective portion 52 that cannot be detected due to overlapping with a normal striped pattern, and the defective portion 52 can be detected. For example, when the crack 52c exists as a defect in the inspection object 50, the first irradiation with the striped pattern 190 is performed with respect to the extending direction of the crack 52c as shown in FIG. Since the extending direction of the striped pattern 190 is orthogonal, the defect pattern 195 that is a collapsed or disturbed portion of the striped pattern 190 due to the crack 52c does not occur. On the other hand, as shown in FIG. 19B, by changing the irradiation position of the striped pattern 190, for example, the striped pattern 190 becomes parallel to the extending direction of the crack 52c. Thereby, a defect pattern 195 is generated due to the crack 52c, and the presence of the defect portion 52 can be detected. Further, for example, when a void 52d exists as a defect in the inspection object 50, the first irradiation with the striped pattern 190 causes the void 52d and the striped pattern as shown in FIG. Since 190 overlaps, the defect pattern 195 due to the void 52d does not appear apparently. On the other hand, as shown in FIG. 20B, by changing the irradiation position of the striped pattern 190, for example, the width dimension of the stripe of the striped pattern 190 is changed. Thereby, the hidden defect pattern 195 caused by the void 52d appears, and the presence of the defect portion 52 can be detected.
As is clear from these examples, the irradiation position is changed at least once per one planar view obtained by one detection operation, that is, one imaging operation by the imaging device 120. In other words, it is preferable to irradiate at least two types of striped patterns 190.

  When the mask plate 1142 is used as the light shielding member 114, the first mask plate 1142-1 and the second mask plate 1142-2 are arranged in two upper and lower stages with respect to the light from the light source 112 as shown in FIG. To do. Each mask plate 1142 can be manufactured by forming a slit by printing a striped pattern 190 on a transparent body or by forming a slit in an opaque body. The slit 1142a is a portion that forms a bright portion of the striped pattern 190, that is, a translucent portion. The width of the slit 1142a may be the same or different between the first mask plate 1142-1 and the second mask plate 1142-2. The projection position changing device 115 includes a mask driving unit that relatively moves the first mask plate 1142-1 and the second mask plate 1142-2 along the width direction 1143 of the slit 1142a. The width dimension of each slit 1142a in the first mask plate 1142-1 and the second mask plate 1142-2 can be changed by the operation of the mask driving unit. Further, the projection position changing device 115 includes the rotation mechanism as described above, and rotates the first mask plate 1142-1 and the second mask plate 1142-2 as a unit on a plane, or the first mask plate 1142-. The light source 112 provided with the first and second mask plates 1142-2 can be rotated together with the first mask plate 1142-1 and the second mask plate 1142-2. Thereby, the irradiation position of the striped pattern 190 on the inspection object 50 can be changed.

  Further, when the mask plate 1142 is used as the light shielding member 114, the light source 112 can be arranged closer to the light source 112 than when the strip plate 1141 is used, so that a large amount of light can be obtained and the apparatus configuration can be reduced.

  In the configuration described above, the strip plate 1141 and the mask plate 1142 are provided on the light emitting surface of the light source 112, and these are replaced or moved. However, as the irradiation device 110, as shown in FIG. A display device 118 such as a display panel (LCD) can also be used. That is, the control device 180 displays the striped pattern 190 on the display surface 118a of the display device 118, and irradiates the display 50 with the display as it is. Since the displayed striped pattern 190 can be freely changed by the control device 180, the structure can be made simpler than the configuration using the strip-shaped plate 1141 or the like.

Further, the irradiation device 110 may be configured as shown in FIG. That is, the irradiation device 110 includes a light source 112 and a pattern member 116 as an example that performs the function of the pattern forming device 113. The pattern member 116 is a plate material on which a striped pattern 190 is printed. In this configuration, the light source 112 is disposed on the side of the pattern member 116, and the object 50 is irradiated with light reflected by the pattern member 116. Therefore, the light source 112 functions as a primary light source, and the pattern member 116 functions as a secondary light source. By adopting such a configuration, it is possible to simply form the striped pattern 190 without using a slit processing member such as the mask plate 1142 or a combination of the strip-shaped plates 1141.
In the configuration shown in FIG. 7, as in the configuration shown in FIG. 3, the light source 112 can be arranged below the pattern member 116, and the light source 112 can be omitted.

  Furthermore, when the inspection object 50 is a fluid, the irradiation device 110 may have a configuration as shown in FIG. That is, the irradiation device 110 includes a light source 112 and a storage container 117 that stores the fluid-like object 50 and is made of a transparent body or a translucent body. Here, the storage container 117 is provided with a pattern forming portion 1171 located between the light source 112 and the inspection object 50 and having a striped pattern 190 formed thereon. The pattern forming unit 1171 has, for example, a form in which a stripe pattern 190 such as a vertical stripe pattern 191a or a horizontal stripe pattern 191b is formed on the light source facing surface 117a of the storage container 117 by printing or the like.

  The imaging device 120 includes a camera unit 121 having an electronic imaging device made of CCD or CMOS. As the camera unit 121, various types such as a so-called area camera, line camera, line scanner, and the like can be used. Further, the type of color or monochrome is not limited in relation to the inspection object 50. Furthermore, the imaging apparatus 120 may include a camera moving mechanism 122 that moves the camera unit 121 in a uniaxial direction or in a circular shape in relation to the inspection object 50 and the inspection method. The camera moving mechanism 122 is not limited to the mechanism that moves the camera unit 121, but functions as a mechanism that relatively moves the camera unit 121 and the inspection object 50. Further, as the imaging device 120, a scanner 123 can be used as shown in FIG. 9 instead of the configuration of the camera unit 121 and the camera moving mechanism 122.

The detection device 130 acquires a signal from the camera unit 121 and converts it into digital information, a calculation unit that performs calculation processing on digital image data, and a storage unit that stores digital image data and other inspection parameters , An input / output unit with the control device 180 that controls the striped pattern 190 in the irradiation device 110, and the like. It is also possible to serve as the control device 180.
As a method for identifying the defective portion 52 in the detection apparatus 130, a normal image receiving pattern in the inspection object 50 in which the defective portion 52 does not exist is stored, and a difference from the inspected image pattern is checked. A known method such as a method of storing graphic information of the pattern 190 in advance and examining abnormal pixels only on the received image data can be employed. In any identification method, it is not necessary that the received image data is faithful to the striped pattern 190. For example, even when the camera unit 121 is focused on the surface 51 of the inspection object 50 or the central portion in the thickness direction, the striped pattern 190 that has passed through the inspection object 50 becomes a blurred image. In the striped pattern 190, those portions can be identified as defects based on the occurrence of a change in luminance or color in a position or direction where the change does not originally occur.
The relationship between the method for identifying the defective portion 52 and the width W1 and the gap W2 will be described later because it is related to the defect inspection method.

  The operation of the defect inspection apparatus 101 configured as described above, that is, the defect inspection method will be described below. The basic principle of defect inspection is as described above, and the defect inspection method is also executed by applying this based on the basic principle. The defect inspection method is executed according to the operation control of the control device 180. Further, as described above, an appropriate striped pattern 190 to be used is selected according to the inspection object 50.

  For example, a liquid crystal glass substrate, a liquid crystal filter, a liquid crystal front panel, or the like, and an object to be inspected 50 having a defective portion 52 on the surface 51, for example, through a mask plate 1142 as shown in FIG. For example, irradiation light 111 having a vertical stripe pattern 191 a shown in FIG. 16 as a single stripe pattern is applied to the inspection object 50, and the irradiation light 111 that has passed through the inspection object 50 is captured by the camera unit 121 for the first time. Do. The captured image is sent from the camera unit 121 to the detection device 130 and subjected to image processing, and the presence or absence of the defect pattern 195 is determined according to the method for identifying the defect portion 52 in the detection device 130 described above. If the defect pattern 195 is found by the first captured image, the inspection object 50 is determined to be defective, the defect inspection of the inspection object 50 is finished, and the next inspection object 50 is completed. You can move on to inspection.

On the other hand, when the defect pattern 195 is not found from the first captured image, the projection is performed in order to avoid accidental non-detection of the defect portion 52 as described with reference to FIGS. 19 and 20. The position change device 115 moves the mask plate 1142 to change the irradiation position of the striped pattern 190 on the inspection object 50 to a position different from the first time. That is, the second striped pattern is changed to, for example, the horizontal striped pattern 191b, and the irradiation light 111 having the horizontal striped pattern 191b is irradiated to the inspection object 50. The irradiation light 111 that has passed through the inspection object 50 is imaged a second time by the camera unit 121, and the presence or absence of the defect pattern 195 is determined by the detection device 130. When the defect pattern 195 is not detected by the second imaging, the inspection object 50 is determined as a non-defective product. When the defect pattern 195 is detected by the second imaging, the inspection object 50 is determined as a defective product.
As described above, the defect inspection is sequentially performed on the inspection object 50.

  As another inspected object 50 using the striped pattern 190 of the vertical stripe pattern 191a and the horizontal stripe pattern 191b and using the same method as described above, the inspected object 50 is a translucent object as shown in FIG. An object having defects 52 such as cracks and bubbles inside, for example, an inspection object 50 such as a ceramic thin plate, a colored resin material, ground glass, and uneven coating on the surface 51 of the inspection object 50 as shown in FIG. An object to be inspected 50 in which bubbles are present at the time of sticking the sealing material can be mentioned.

Below, the example of the inspection method suitable for the other to-be-inspected object 50 is demonstrated.
When a line camera is used as the camera unit 121 by using a concentric striped pattern 192 as shown in FIG. 17 for a convex lens-like curved surface such as an optical lens or a circular inspection object 50 such as an optical disk. As shown in FIG. 21, the camera moving mechanism 122 rotates the camera unit 121 in a circle around the center point of the inspection object 50 to perform imaging, or a circle around the center point of the inspection object 50. When the inspection object 50 is rotated, an image is taken, or when an area camera is used as the camera unit 121, an entire image is taken. As described above, the camera moving mechanism 122 is a mechanism that relatively moves the camera unit 121 and the inspection object 50.

  Further, when the inspection object 50 is a transparent molded product, for example, when the inspection object 50 has a specific shape such as the PTP, the blister pack, the electric lamp cover, the headlight lens, etc., the outside of the inspection object 50 Imaging is performed by the imaging device 120 using, for example, polygonal stripe patterns 193a to 193c as shown in FIG. 18 corresponding to the shape.

  Further, when the inspection object 50 is a long object, such as a film material or an optical fiber, a vertical stripe pattern 191a or a horizontal stripe pattern 191b as shown in FIG. As shown in FIG. 4, the camera moving mechanism 122 moves the camera unit 121 along the axial direction 53 of the inspection object 50 to perform imaging. In this case, the camera unit 121 is preferably a line sensor.

  When the inspection object 50 is a transparent cylindrical object such as a bottle or a plastic bottle, the camera unit 121 is used as shown in FIG. 23 using, for example, the stripe pattern 190 of the vertical stripe pattern 191a or the horizontal stripe pattern 191b. When the line camera is used, the object to be inspected 50 is rotated around the central axis by the rotating device 54 and imaged, or when the area 121 is used as the camera unit 121, the entire surface is imaged. The camera unit 121 and the inspected object 50 may be relatively rotated. The inspected object 50 is fixed, and the irradiation device 110 and the imaging device 120 are integrally rotated about the central axis. Also good.

  When the inspection object 50 is a fluid, the inspection is executed as already described with reference to FIG.

As described above, since the irradiation position of the striped pattern 190 with respect to the inspection object 50 is changed including changing the width W1 and the gap W2 in the striped pattern 190, the book as described above. Factors that most affect the minimum detection size of the defect portion 52 in the defect inspection method of the embodiment are the optical resolution of the camera portion 121 and the S / N ratio of the captured image in the camera portion 121.
Even when the irradiation position of the striped pattern 190 is not changed, as long as the shape of the defect portion 52 is unknown, the defect pattern 195 obtained corresponding to the defect portion 52 and the defect portion in the inspection object 50 are obtained. It is difficult to specify the positional relationship with the actual location of 52.
In the measurement method described above, in principle, by providing a change in the striped pattern 190 of at least one period within the planar visual field size of the defect portion 52, the image reception due to the defect portion 52 is disturbed stochastically. The generated defect 52 should be easily recognized. On the other hand, in order to identify the disturbance of the striped pattern 190 on the received image data, the disturbance must be recognized with a dimension at least greater than the optical resolution. Therefore,
Optical resolution r [μm]
Pattern change (W1 + W2) p [μm]
Minimum defect size d [μm]
The theoretical value of each dimension is
d ≧ p ≧ (2 × r)
It can be expressed by the relationship. The minimum defect dimension d corresponds to the minimum detection dimension.
As can be seen from the above relationship, the value obtained by adding the width W1 and the gap W2 in the striped pattern 190 can be arbitrarily changed as described above, but needs to be at least twice the optical resolution. Here, “twice” is attributed to the fact that the striped pattern 190 is formed with the width W1 and the gap W2. Regardless of the nature of the defective portion 52, the optimum condition is obtained when the width W1 and the gap W2 are equal.

  The above-mentioned relationship is the optimum condition when the image is captured only once within the plane visual field size of the defect portion 52. When the striped pattern 190 is moved and imaged a plurality of times, the stripe pattern 190 The minimum detection size of the defective portion 52 varies depending on the amount of movement and the number of times of imaging. That is, of course, the smaller the defect portion 52 can be detected as the striped pattern 190 is moved more finely or the number of times of movement is increased while satisfying the above relationship. For example, when the width W1 and the gap W2 are each 100 μm, the amount of movement of the striped pattern 190 is 50 μm, and the number of times of imaging is two, the width W1 and the gap W2 are each 50 μm and the number of times of imaging is one. The same minimum detection size is obtained. That is, it becomes 100 μm by two movements, and it becomes the same slit position as the original pattern, the lightness and darkness are reversed, but the relationship with the detection dimension becomes the same.

  As described above, when imaging is performed a plurality of times within one plane visual field dimension for the defect portion 52, the minimum detection size of the defect portion 52 varies depending on the amount of movement of the striped pattern 190 and the number of imaging operations. The resolution r, the pattern change p, and the minimum defect size d do not simply satisfy the above-described relationship. The defective portion 52 can be detected with high detection accuracy. One example will be described below.

  When a liquid crystal panel protective cover that is a so-called screen surface member attached to the entire surface of the liquid crystal panel is the object to be inspected 50, the liquid crystal panel protective cover has one dot of the liquid crystal panel that is abnormal in appearance, that is, about It is required to detect a defective part of 0.2 mm or more. When the above-described relationship among the optical resolution r, the pattern change p, and the minimum defect size d is simply applied, the width W1 and the gap W2 are each set to be equivalent to a 1/2 dot size, A defective part can be detected by one imaging. At this time, the optical resolution sufficiently satisfies the above relationship. The inspection is performed by, for example, using a striped pattern described with reference to FIG. 6 for another liquid crystal panel having a dot pitch smaller than the dot pitch of the liquid crystal panel to which the liquid crystal panel protective cover as the inspection object 50 is attached. It can be realized by using it as a light source for generating 190 (hereinafter referred to as a pattern light source). On the other hand, generally, when the striped pattern 190 is received by the camera unit 121, the contrast of light and dark tends to decrease as the striped pattern 190 becomes thinner due to the effects of light diffraction and interference. When the contrast is lowered, the defect portion 52 having a poor feature is less likely to be detected because disturbances in brightness and darkness are reduced. In order to increase the contrast, a method of enlarging the width W1 and the gap W2 of the striped pattern 190 is conceivable. However, if the width W1 and the gap W2 are increased, the defect is not detected as described above in one imaging. There arises a problem that the minimum detection size of the portion 52 is also increased.

  Therefore, as a method for solving the above problem, the applicant has devised an inspection method in which imaging is performed a plurality of times within one plane visual field dimension for the defect portion 52 as follows. That is, the inspection object 50 is required to detect a defective portion equivalent to about 0.2 mm or more by the liquid crystal panel protective cover, and a liquid crystal panel is used as the pattern light source. The dot pitch in the pattern light source is as described above. The thickness is about 0.1 mm, which is smaller than 0.2 mm. Under such conditions, the width W1 and the gap W2 of the striped pattern 190 are set to 5 dots (about 0.1 .0 mm) instead of about 0.1 mm, which is the minimum formation width of the pattern light source. 5mm). Here, for each dimension of the width W1 and the gap W2, the value of “5 times” the value of 1/2 of the minimum defect dimension d, which is about 0.2 mm in this example, is set by the applicant's experiment, etc. Based on the results obtained. Thus, by ensuring that the dimension p of the width W1 + the gap W2 is larger than the minimum defect dimension d, the contrast is ensured as described above. On the other hand, the striped pattern 190 corresponds to one dot of the pattern light source along the width direction in the dark part and the bright part of the striped pattern 190 in a state where the dimension p of (width W1 + gap W2) is maintained. Move 5 times each distance. Then, for each moving operation, the striped pattern 190 that has passed through the inspection object 50 is imaged. By performing the inspection in this way, each dimension of the width W1 and the gap W2 is set so as to correspond to the above-mentioned 1 dot (about 0.1 mm), and the same detection accuracy, that is, the same as when the image is taken only once. It becomes possible to detect a defect 52 having a minimum defect dimension d of about 0.2 mm in the example.

  In this way, when the set dimension p of (width W1 + gap W2) exceeds the minimum defect dimension d, in other words, the above-described minimum defect dimension d ≧ The number of movements of the striped pattern 190, that is, the light shielding member 114, in other words, the number of imaging times and the movement distance are set so as to satisfy the same defect detection accuracy as when the relationship of the dimension p of (width W1 + gap W2) is satisfied. It can be seen that control is required. That is, the control device 180 may control the operation of the projection position changing device 115 and the imaging device 120. Here, the optical resolution r sufficiently satisfies the above-described relationship, p ≧ 2r, and imaging is performed every time the striped pattern 190 is moved.

  In the inspection method by multiple imaging as described above, the minimum defect size d is very small and the width W1 and the clearance W2 are satisfied so as to satisfy the relationship of the minimum defect size d ≧ (width W1 + gap W2). It is an effective method when sufficient defect detection accuracy cannot be obtained if each dimension is set and the imaging operation is performed only once.

  In the above description, with respect to the movement of the striped pattern 190 a plurality of times, the striped pattern 190 is replaced with the dark portion and the bright portion of the striped pattern 190 while maintaining the dimension p of (width W1 + gap W2). The case of moving a plurality of times along the width direction is taken as an example. However, the concept of “moving the striped pattern 190 a plurality of times” is not limited to the above example, but also includes moving the striped pattern 190 by changing the dimensions of the width W1 and the gap W2. Includes the movement of the striped pattern 190 that performs both the state in which the dimensions of the width W1 and the gap W2 are maintained and the case where the width W1 is changed, and also in the moving direction in the dark part and the bright part of the striped pattern 190. The concept is not limited to the width direction, and includes a rotation of the striped pattern 190 and a combination of the rotation and the width direction.

  Further, in the defect inspection apparatus 101, for each inspection object 50, the dimensions of the width W <b> 1 and the gap W <b> 2, the number of movements of the striped pattern 190, and the relationship between the movement dimensions are stored in a storage unit provided in the detection apparatus 130. The control device 180 controls the operations of the projection position changing device 115, the imaging device 120, the detection device 130, and the irradiation device 110 so as to satisfy the above-described relationship, d ≧ p ≧ 2r. A defect inspection can be automatically performed according to the inspection object 50.

  In the embodiment described above, various modified examples have been described, but the defect inspection apparatus 101 can be configured by further combining one or more modified examples.

  The present invention relates to a defect inspection apparatus and method for detecting a defect by measuring transmitted light with respect to an object having translucency such as glass, a resin body, a thin ceramic material, and a liquid, and a surface of the inspection object. The present invention can be applied to a defect inspection apparatus and method that can detect defects such as irregularities, cracks, internal bubbles, and density of light transmittance regardless of their shapes and directions.

It is a block diagram which shows the structure of the defect inspection apparatus in embodiment of this invention. It is a perspective view for demonstrating one structural example of the irradiation apparatus shown in FIG. It is a perspective view for demonstrating the other structural example of the irradiation apparatus shown in FIG. It is a perspective view of the light-shielding member shown in FIG. It is sectional drawing of the light-shielding member shown in FIG. It is a top view which shows the other structural example of the irradiation apparatus shown in FIG. It is a perspective view which shows the other structural example of the irradiation apparatus shown in FIG. It is a front view which shows the other structural example of the irradiation apparatus shown in FIG. It is a perspective view for demonstrating the other structural example of the imaging device shown in FIG. It is a figure for demonstrating the principle of the defect inspection in the defect inspection apparatus shown in FIG. It is a figure for demonstrating the principle of the defect inspection in the defect inspection apparatus shown in FIG. It is a figure for demonstrating the principle of the defect inspection in the defect inspection apparatus shown in FIG. It is a figure which shows an example of the defect part which can be detected with the defect inspection apparatus shown in FIG. It is a figure which shows the other example of the defect part which can be detected with the defect inspection apparatus shown in FIG. It is a figure which shows the other example of the defect part which can be detected with the defect inspection apparatus shown in FIG. It is a figure which shows an example of the striped pattern which can generate | occur | produce with the irradiation apparatus shown in FIG. It is a figure which shows the other example of the striped pattern which can generate | occur | produce with the irradiation apparatus shown in FIG. It is a figure which shows the other example of the striped pattern which can generate | occur | produce with the irradiation apparatus shown in FIG. It is a figure for demonstrating the defect inspection method in the defect inspection apparatus shown in FIG. It is a figure for demonstrating the defect inspection method in the defect inspection apparatus shown in FIG. It is a figure for demonstrating an example of the defect inspection method performed with the defect inspection apparatus shown in FIG. It is a figure for demonstrating the other example of the defect inspection method performed with the defect inspection apparatus shown in FIG. It is a figure for demonstrating the other example of the defect inspection method performed with the defect inspection apparatus shown in FIG. It is a figure for demonstrating the inspection method in the conventional defect inspection apparatus. It is a figure for demonstrating the inspection method in the conventional defect inspection apparatus.

Explanation of symbols

50 ... Inspection object, 52 ... Defect,
DESCRIPTION OF SYMBOLS 101 ... Defect inspection apparatus, 110 ... Irradiation apparatus, 111 ... Irradiation light, 112 ... Light source,
113 ... Pattern forming device, 114 ... Light shielding member, 115 ... Projection position changing device,
116 ... Pattern member, 117 ... Storage container, 118 ... Display device, 118a ... Display surface,
120 ... Imaging device 122 ... Moving mechanism 130 ... Detection device 190 ... Striped pattern
195 ... defect pattern,
1142 ... Mask plate, 1422a ... Slit, 1171 ... Pattern forming part.

Claims (14)

In the defect inspection apparatus for detecting the defect portion (52) of the inspection object based on the transmitted light that has passed through the inspection object (50) having transparency,
An irradiation device (110) for irradiating the inspection object with irradiation light (111) having a striped pattern (190);
An imaging device (120) that images the striped pattern that has passed through the inspection object;
A detection device (130) connected to the imaging device and detecting a defect pattern (195) appearing in accordance with the defect from the striped pattern;
A defect inspection apparatus comprising:   The defect inspection apparatus according to claim 1, wherein the irradiation apparatus includes a light source (112) and a pattern forming apparatus (113) provided between the light source and the inspection object to form the striped pattern.   The pattern forming apparatus includes: a light shielding member (114) that forms the striped pattern; and a projection position changing device (115) that moves the light shielding member to change the irradiation position of the striped pattern on the inspection object. The defect inspection apparatus according to claim 2, comprising:   The light shielding member has two mask plates (1142-1, 1142-2) each formed with a slit (1142a), and the projection position changing device relatively moves the mask plate to The defect inspection apparatus according to claim 3, wherein the shape of the striped pattern is further changed.   The striped pattern is a pattern in which dark portions having a width W1 and bright portions having a width W2 are alternately arranged. When d is the size of the minimum defective portion to be detected, d ≧ The defect inspection apparatus according to claim 3 or 4, further comprising a control device (180) for performing an operation control for moving the light shielding member to a position satisfying a relationship of (W1 + W2) with respect to the projection position changing device.   When the striped pattern has the dark part and the bright part having a relationship of d <(W1 + W2), the control device controls the operation of the projection position changing device to move the light shielding member, and the imaging The defect inspection apparatus according to claim 5, wherein the apparatus performs an operation control for imaging the striped pattern that has passed through the inspection object every time the light shielding member moves.   The defect inspection apparatus according to claim 1, wherein the irradiation apparatus is a display apparatus (118) that displays the striped pattern on the display surface (118 a) and irradiates the inspection target with the striped pattern.   The said irradiation apparatus has a light source (112) and the pattern member (116) which displays the said striped pattern, reflects the light from the said light source as said irradiation light, and irradiates the said to-be-inspected object. Defect inspection apparatus as described.   The defect inspection according to claim 1, wherein the irradiation device includes a light source (112), and further includes a moving device (122) that relatively moves the object to be inspected and the imaging device. apparatus.   The inspection object is a fluid, and the irradiation device is a storage container that stores a light source (112) and a fluid-like inspection object, and is located between the light source and the inspection object. The defect inspection apparatus according to claim 1, further comprising a storage container (117) having a pattern forming portion (1171) in which a striped pattern is formed.   The defect inspection apparatus according to claim 1, wherein the irradiation apparatus irradiates the inspection object with the irradiation light having a color different from that of the inspection object.   The defect inspection apparatus according to claim 1, wherein the imaging apparatus is a scanner. In the defect inspection method for detecting the defect portion (52) of the inspection object based on the transmitted light that has passed through the inspection object (50) having transparency,
Irradiate the inspection object with irradiation light consisting of a striped first pattern,
Irradiating the object to be inspected with irradiation light composed of a second pattern having a stripe shape different from the first pattern,
Imaging the first striped pattern and the second striped pattern that have passed through the inspection object,
Detecting a defect pattern (195) appearing in accordance with the defect from at least one of the first stripe pattern and the second stripe pattern;
A defect inspection method characterized by that. Each of the first and second striped patterns is a pattern in which dark portions having a width W1 and bright portions having a width W2 are alternately arranged, and the size of the minimum defective portion to be detected When the thickness is d, the pattern satisfies the relationship of d ≧ (W1 + W2), and the first and second striped patterns have the dark portion and the bright portion having the relationship of d <(W1 + W2). The light shielding member (114) for creating the first and second striped patterns is moved, and each time the light shielding member moves, the first and second striped patterns that have passed through the inspection object are moved. The defect inspection method according to claim 13, wherein imaging is performed.

Images