JP5090147B2 - Defect inspection method, defect inspection apparatus, and line-shaped light source device used therefor - Google Patents

Description

  The present invention belongs to the technical field of defect inspection, and particularly relates to a method and apparatus for inspecting defects such as scratches on an inspection object and a line light source device used therefor.

  The present invention can be applied to, for example, inspecting the presence or absence of structural defects such as scratches on the surface or inside of a sheet-like or plate-like material as an inspection object.

  Light emitted from a line-shaped light source to a traveling sheet-like or plate-like inspection object for the purpose of inspecting for defects such as scratches present on the inspection object made of a sheet-like or plate-like material with a smooth surface In recent years, there are many methods and devices for detecting the presence of defects such as scratches on an inspection object by reading scattered light, for example, diffusely reflected by the scratches with a monitor camera. It is used.

  The principle of defect detection by such defect inspection will be described below with reference to FIGS.

In the case of FIG. 11 and FIG. 12, the inspection surface of the inspection object 6 is a mirror surface that reflects light almost uniformly, and the light emitted from the line-shaped light source 7 is from 60 ° with respect to this inspection surface. illuminated with a small angle theta _2. However, the line-shaped light source 7 is arranged to extend in a line shape in a direction perpendicular to the drawing sheet. When there is no defect on the inspection surface, the light is reflected only in the direction symmetrical to the incident light with respect to the inspection surface normal as shown in FIG. 11, and no light enters the monitor camera 8. However, when the defect 12 such as a scratch exists on the inspection surface, the light is irregularly reflected at the portion of the defect 12 as shown in FIG. 12, and scattered light is generated. A part of the scattered light enters the monitor camera 8 and the presence of a defect 12 such as a scratch can be detected.

  When the inspection object 6 is made of a material that transmits light, the inspection object 6, the line light source 7 and the monitor camera 8 are arranged as shown in FIG. 13 to transmit light to the inspection object 6. By doing so, it is possible to inspect the defect of the inspection object 6. In this case, in a portion having no defect, the transmitted light proceeds as shown in the figure and does not enter the monitor camera 8. However, in a portion where there is a defect 12 such as a scratch, a part of the scattered light generated by the defect 12 is incident on the monitor camera 8 as shown in FIG. 14, and the defect can be detected.

As a light source used for the defect inspection as described above, there is a light emitting diode (LED) illumination in which a plurality of light emitting diodes are arranged in a line as described in Patent Document 1. There are two types of light-emitting diode illumination, in which light-emitting diodes are simply arranged side by side, and diffused light is generated by arranging a diffuser plate at the exit end.
JP 2001-215115 A

The problems of the background art as described above will be described with reference to FIG. The intensity of scattering when light irradiated with directivity on an inspection object is scattered by a flaw existing on the object depends on the light irradiation direction and the extension direction of the flaw. In other words, if the direction of the scratch is perpendicular or close to the light irradiation direction, the intensity of the scattered light from the scratch is high, so the detection accuracy of the scratch is high, but the scratch extension direction is the light irradiation direction. However, if it is parallel to or close to this, the intensity of scattered light due to scratches is not high, so that the detection accuracy of the scratches by the monitor camera 8 is low. When the light source 7 having high directivity as shown in FIG. 15 is used, the light is irradiated at an angle θ ₂ smaller than 60 ° with respect to the inspection surface of the inspection object 6 as described above. 15 is irradiated only in the direction indicated by the arrow in FIG. 15, so that a defect extending in the direction such as the scratch a existing on the inspection object 6 can be easily detected, but the scratch b Such a defect extending in the direction is difficult to detect because almost no scattered light is generated.

  As described above, in the method of concentrating the light of the light emitting diode without using the diffuser plate and having directivity, the scratches extend in the direction near the optical axis of the light emitting diode having the highest light intensity. If the directions are parallel or close to each other, the detection accuracy is low.

  On the other hand, in the method in which the diffusion plate is arranged in the light emitting diode illumination, the directivity with respect to the scratch is weak, but the illuminance with respect to the inspection object becomes extremely low and the detection sensitivity becomes low.

  Further, as shown in FIG. 16, when the inspection object 6 is inspected by transmitting light, the light emitted from the light emitting portion (light emitting diode chip) 3a of the light emitting diode 3 passes through defects such as scratches. Without being incident on the monitor camera 8, it becomes a bright spot and it becomes difficult to distinguish it from defects such as scratches.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a defect inspection method and apparatus capable of solving the above-described problems and accurately detecting defects such as various scratches existing on an inspection object made of a sheet-like or plate-like material. The present invention also provides a line light source device used therefor.

According to the present invention, the above object is achieved as follows:
In the method for inspecting a defect in the inspection object by irradiating the inspection object with light emitted from a line light source device and detecting the light that has passed through the inspection object,
As the line-shaped light source device, a plurality of light emitting diode arrays, each having a plurality of light emitting diodes arranged linearly so that their optical axes are parallel to each other, are arranged in a plurality of stages, and the direction of the optical axis of the light emitting diodes is Use different ones for each LED array,
A defect inspection method characterized by inspecting a defect in the inspection object based on a detection signal obtained by detecting light passing through the inspection object by a light detection means;
Is provided.

In one aspect of the present invention, the light emitting diode array is disposed in two stages, and in one stage of the light emitting diode array, an angle formed by an optical axis of the light emitting diode with respect to a linear array direction of the light emitting diodes θ ₁ is in the range of 0 ° <θ ₁ <90 °, and in the other stage light emitting diode array, an angle θ ₁ formed by the light axis of the light emitting diode with respect to the linear array direction of the light emitting diode is 90 °. <Θ ₁ <180 °. In one aspect of the present invention, an angle θ ₂ formed by a surface including the optical axes of the plurality of light emitting diodes in the light emitting diode array with respect to the surface of the inspection object is in a range of 0 ° <θ ₂ <60 °. Within. In one aspect of the present invention, a light emitting portion of the light emitting diode is not seen from a direction orthogonal to the linear array direction of the light emitting diodes in a plane including the optical axes of the plurality of light emitting diodes in the light emitting diode array. Shield from light.

In addition, according to the present invention, the above-mentioned object is achieved as follows:
A plurality of light emitting diode arrays each having a plurality of light emitting diodes arranged linearly so that the optical axes thereof are parallel to each other are arranged in a plurality of stages, and the direction of the optical axis of the light emitting diodes is the same for each of the light emitting diode arrays. A line-shaped light source device, characterized in that
Is provided.

In one aspect of the present invention, the light emitting diode array is arranged in two stages, and in one stage of the light emitting diode array, an angle formed by an optical axis of the light emitting diode with respect to a linear array direction of the light emitting diodes. θ ₁ is in the range of 0 ° <θ ₁ <90 °, and in the light emitting diode array at the other stage, the angle θ ₁ formed by the optical axis of the light emitting diode with respect to the linear array direction of the light emitting diode is 90. It is in the range of ° <θ ₁ <180 °. In one aspect of the present invention, a light emitting portion of the light emitting diode is not seen from a direction orthogonal to the linear array direction of the light emitting diodes in a plane including the optical axes of the plurality of light emitting diodes in the light emitting diode array. Is provided with a light shielding member for shielding light.

In addition, according to the present invention, the above-mentioned object is achieved as follows:
In an apparatus for inspecting a defect in the inspection object by irradiating the inspection object with light emitted from a line-shaped light source device, and detecting light that has passed through the inspection object,
The line light source device is the line light source device described above,
A defect inspection apparatus comprising light detection means for detecting light passing through the inspection object and outputting a detection signal;
Is provided.

In an aspect of the present invention, an angle θ ₂ formed by a surface including the optical axes of the plurality of light emitting diodes in the light emitting diode array with respect to the surface of the inspection object is in a range of 0 ° <θ ₂ <60 °. Inspection object moving means for moving the inspection object to be inside is provided.

  According to the present invention as described above, as the line-shaped light source device, a plurality of light-emitting diode arrays, in which a plurality of light-emitting diodes are linearly arranged so that their optical axes are parallel to each other, are arranged in a plurality of stages, By using a light emitting diode whose optical axis direction is different for each light emitting diode array, even if a defect such as a scratch in any extending direction exists on the inspection object, each defect is different from each other. Since light is irradiated from a plurality of directions, light can always be irradiated from a direction that is not parallel to the extending direction of each defect. Accordingly, it is possible to accurately detect defects such as various scratches existing on the inspection object and perform a good defect inspection.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of a defect inspection method, a defect inspection apparatus, and a line light source device used therefor will be described with reference to the drawings.

  FIG. 1 is a schematic side view showing an embodiment of a defect inspection method, a defect inspection apparatus, and a line light source device according to the present invention, FIG. 2 is a schematic plan view thereof, and FIG. 3 is a schematic enlarged plan view thereof. FIG. In the line light source device 7 of the present embodiment, a light emitting diode array formed by linearly arranging a plurality of light emitting diodes 3 in the X direction is arranged in two stages. FIG. 4 is a schematic perspective view of the line light source device 7, and FIGS. 5 and 6 are schematic views showing the direction of the optical axis C of the light emitting diode array. FIG. 7 is a circuit diagram of the line light source device 7.

  The light emitting diode array of one stage is indicated by reference numeral 3A, and the light emitting diode array of the other stage is indicated by reference numeral 3B. In the light emitting diode array at each stage, the optical axes C of the plurality of light emitting diodes 3 are parallel to each other, and the plurality of light emitting diodes 3 are in the same direction. The light emitting diode arrays 3A and 3B are arranged in the casing 2 as shown in FIGS. Specifically, as shown in FIGS. 1 and 6, each light emitting diode 3 is attached to a mounting substrate 27 disposed in the casing 2. As shown in FIG. 7, in each of the light emitting diode arrays 3A and 3B, the light emitting diodes 3 are connected in series, and the light emitting diode arrays 3A and 3B are connected in parallel, and FIGS. It is driven by a power supply device (LED drive device) 13 shown in FIG.

In the present embodiment, the direction of the optical axis C of the light emitting diode 3 is different for each light emitting diode array. That is, for example, an angle θ ₁ (an angle measured counterclockwise with respect to the X direction) formed by the optical axis C of the light emitting diode 3 with respect to the direction (X direction) of the linear array of the light emitting diodes 3 is shown in FIGS. As shown in FIG. 4, the light emitting diode array 3A and the light emitting diode array 3B are different. Specifically, for example, in the light emitting diode array 3A, the angle θ ₁ is in the range of 0 ° <θ ₁ <90 ° and is, for example, 45 °, whereas in the light emitting diode array 3B, the angle θ 1 ₁ is in the range of 90 ° <θ ₁ <180 °, for example 135 °. The difference between the angle theta ₁ at an angle theta ₁ and the light emitting diode array 3B in the light-emitting diode array 3A is preferably 45 ° to 135 °, more preferably 60 ° to 120 °, for example 90 °. The surface including the optical axis C of the plurality of light emitting diodes 3 in the light emitting diode array 3A and the surface including the optical axis C of the plurality of light emitting diodes 3 in the light emitting diode array 3B are parallel to each other.

As shown in FIGS. 1 to 3, an inspection object 6 made of a sheet-like or plate-like material is moved by an arrow T in the Y direction perpendicular to the X direction by an inspection object moving means (not shown) such as a belt conveyor. It is moved in the direction. The surface of the inspection object 6 is parallel to the XY plane. As shown in FIG. 1, the surface including the optical axis C of the plurality of light emitting diodes 3 in the light emitting diode arrays 3 </ _b > A and 3 </ _b > B forms an angle θ ₂ with respect to the surface of the inspection object 6. This angle θ ₂ is, for example, in a range of 0 ° <θ ₂ <60 °.

  A monitor camera 8 as a light detection means is arranged above the region of the inspection object 6 irradiated with light emitted from each light emitting diode 3 of the line light source device 7. As shown in FIG. 1, a personal computer 11 is connected to the monitor camera 8. In the personal computer 11, a detection signal output from the monitor camera 8 is input, and based on this, image processing is performed in accordance with a predetermined program, and a defect in the inspection object 6 is inspected.

  In the present embodiment, light (peak intensity light) near the light-emitting diode optical axis C having the highest light intensity among the light emitted from the light-emitting diodes 3 of the line light source 7 belongs to the light-emitting diode array 3A. 1 and those belonging to the light emitting diode array 3B proceed in the direction crossing each other, so that not only the defect extending in the X direction like the scratch a shown in FIG. 1 but also the Y direction like the scratch b Since the peak intensity light is irradiated from a plurality of directions different from each other even if the defect extends in any direction, the defect extends in a direction not parallel to the extension direction of each defect 12. Light is irradiated. Therefore, scattered light is emitted from the defects 12 such as various scratches present on the inspection object 6, and a part of the scattered light reaches the monitor camera 8 and is detected. Thus, it is possible to detect a defect with high accuracy and perform a good defect inspection.

  The microcomputer 11 can also perform necessary data processing on the detected defect and output an alarm for detecting the defect.

  An example based on this embodiment is shown below, comparing with a comparative example.

In the embodiment of the present invention, as shown in FIG. 6, the angle θ _{1 is set} to 45 ° in the light emitting diode array 3A, and the angle θ _{1 is set} to 135 ° in the light emitting diode array 3B. Therefore, the difference between the angle θ ₁ in the light-emitting diode array 3A and the angle θ ₁ in the light-emitting diode array 3B was 90 °. As shown in FIG. 6, the pitch of the linear array of the light-emitting diodes 3 in each of the light-emitting diode arrays 3A and 3B was 7.5 mm. As shown in FIG. 1, the angle θ ₂ formed by the surface including the optical axis C of the plurality of light emitting diodes 3 in the light emitting diode arrays 3A and 3B with respect to the surface of the inspection object 6 was 30 °.

  As shown in FIG. 7, the current passed through the light emitting diode 3 in each of the light emitting diode arrays 3A and 3B was 25 mA. The light emitting diode 3 used was NSPG520S (G5) manufactured by Nichia Corporation. As shown in FIG. 1, the distance from the light emitting diode 3 of the line light source device 7 to the scratch 12 formed on the surface of the inspection object 6 and extending in the Y direction was about 25 mm.

On the other hand, in the comparative example, the linear light source device shown in FIG. 8 was used. Here, the angle θ ₁ formed by the optical axis C of the light emitting diode 3 with respect to the linear array direction (X direction) of the light emitting diode 3 was 90 ° in both the light emitting diode arrays 3A and 3B. That is, the difference between the angle theta ₁ at an angle theta ₁ and the light emitting diode array 3B in the light-emitting diode array 3A was 0 °. Other configurations were the same as those in the above example.

  As a result, the flaw 12 could not be detected in the comparative example, but the flaw 12 could be detected in the embodiment of the present invention.

  FIG. 9 is a schematic side view showing another embodiment of the defect inspection method, the defect inspection apparatus, and the line light source apparatus according to the present invention. In this figure, the same code | symbol is attached | subjected to the member or part which has the same function as in the said FIGS.

  In the present embodiment, the line light source device 7 is arranged on the opposite side of the monitor camera 8 with the inspection object 6 interposed therebetween, and the light emitted from the line light source device 7 passes through the inspection object 6.

  The line light source device 7 is different from that of the embodiment described with reference to FIGS. This light shielding member 5 is in a direction (in the plane of FIG. 9) perpendicular to the linear array direction (X direction) of the light emitting diodes 3 in the plane including the optical axis C of the plurality of light emitting diodes 3 in the light emitting diode arrays 3A and 3B. The light-emitting portion (light-emitting diode chip) 3a of the light-emitting diode 3 is shielded from light so that it cannot be seen from above.

  FIG. 10 shows a schematic diagram of the light shielding member 5. The light shielding member 5 is made of a material such as black that does not reflect light, such as black cardboard or an acrylic plate, and has an opening portion 14 that allows light in a required direction range emitted from the light emitting diode 3 to pass through each light emitting diode 3. Have The opening portion 14 is located on an extension line of the shell-shaped body portion of the light emitting diode 3, and has an elongated shape in the linear arrangement direction (X direction) of the light emitting diode 3.

  For example, NSPG520S (G5) manufactured by Nichia Corporation is used as the light-emitting diode 3, black cardboard having a thickness of 0.2 mm is used as the material of the light-shielding member 5, and the light-shielding member 5 is used as the light-emitting diode 3. When the arrangement pitch of the light emitting diodes 3 in each of the light emitting diode arrays 3A and 3B is 10 mm, the length of the opening portion 14 in the arrangement direction is 7 mm, the width is 5 mm, and the arrangement direction of the light shielding portions The length of is suitably 3 mm.

  According to the present embodiment, since it is configured as described above, a defect extending in any direction can be transmitted from a plurality of different directions, as in the embodiments described with reference to FIGS. Therefore, light is always irradiated from a direction that is not parallel to the extending direction of each defect. Therefore, scattered light is emitted from various defects such as scratches present on the inspection object 6, and a part of the scattered light reaches the monitor camera 8 and is detected. Thus, it is possible to detect a defect with high accuracy and perform a good defect inspection. In addition, according to the present embodiment, by providing the light shielding member 5, there is no light reaching the monitor camera 8 from the light emitting portion 3 a of the light emitting diode 3 without passing through defects such as scratches. Therefore, the defect detection accuracy is remarkably improved as compared with the conventional defect inspection method.

It is a typical side view showing one embodiment of a defect inspection method, a defect inspection device, and a line light source device by the present invention. It is a typical side view of embodiment of FIG. FIG. 2 is a schematic enlarged plan view of the embodiment of FIG. 1. It is a typical perspective view of a line-shaped light source device. It is a schematic diagram which shows the light emitting diode array body of the linear light source device of FIG. It is a schematic diagram which shows the light emitting diode array body of the linear light source device of FIG. FIG. 5 is a circuit diagram of the line light source device of FIG. 4. It is a schematic diagram which shows the light emitting diode array of the linear light source device of a comparative example. It is a typical side view which shows other embodiment of the defect inspection method by the present invention, a defect inspection apparatus, and a line light source device. It is a schematic diagram of the light shielding member of the embodiment of FIG. It is explanatory drawing of the principle of the defect detection in the case of inspecting by making light reflect on an inspection object. It is explanatory drawing of the principle of the defect detection in the case of inspecting by making light reflect on an inspection object. It is explanatory drawing of the principle of the defect detection in the case of inspecting by making light permeate | transmit an inspection target object. It is explanatory drawing of the principle of the defect detection in the case of inspecting by making light permeate | transmit an inspection target object. It is explanatory drawing of the defect detection using a light source with high directivity. It is explanatory drawing of test | inspection error generation | occurrence | production in the case of inspecting by making light permeate | transmit an inspection target object.

Explanation of symbols

2 Light source diode casing 3 Light emitting diode 3a Light emitting diode light emitting portion 3A, 3B Light emitting diode array 5 Light shielding member 6 Inspection object 7 Line light source device 8 Monitor camera 11 Personal computer 12 Defect 13 Light emitting diode driving device 14 Light shielding Opening portion 14 of the member
27 Light-Emitting Diode C Substrate C Light-Emitting Diode Optical A and B Scratches

Claims (9)

In the method for inspecting a defect in the inspection object by irradiating the inspection object with light emitted from a line light source device and detecting the light that has passed through the inspection object,
As the line-shaped light source device, a plurality of light emitting diode arrays, each having a plurality of light emitting diodes arranged linearly so that their optical axes are parallel to each other, are arranged in a plurality of stages, and the direction of the optical axis of the light emitting diodes is Use different ones for each LED array,
Shielding the light-emitting portion of the light-emitting diode from the direction perpendicular to the linear array direction of the light-emitting diode in a plane including the optical axis of the plurality of light-emitting diodes in the light-emitting diode array,
A defect inspection method, wherein a defect in the inspection object is inspected based on a detection signal obtained by detecting light having passed through the inspection object by a light detection means. The light emitting diode array is arranged in two stages, and in the light emitting diode array in one stage, an angle θ ₁ formed by the optical axis of the light emitting diode with respect to the linear array direction of the light emitting diode is 0 ° <θ _1. The angle θ ₁ formed by the optical axis of the light emitting diodes with respect to the linear array direction of the light emitting diodes in the light emitting diode array in the other stage is in the range of 90 ° <θ ₁ <180 °. The defect inspection method according to claim 1, wherein the defect inspection method is an inside. Angle θ in the one-stage light emitting diode array ₁ And the angle θ in the light emitting diode array of the other stage ₁ The defect inspection method according to claim 2, wherein the difference is between 60 ° and less than 120 °. An angle θ ₂ formed by a plane including the optical axes of the plurality of light emitting diodes in the light emitting diode array with respect to the surface of the inspection object is in a range of 0 ° <θ ₂ <60 °. The defect inspection method according to any one of claims 1 to 3 . A plurality of light emitting diode arrays each having a plurality of light emitting diodes arranged linearly so that the optical axes thereof are parallel to each other are arranged in a plurality of stages, and the direction of the optical axis of the light emitting diodes is the same for each of the light emitting diode arrays. different way, will have to,
A light-shielding member that shields light from a light-emitting portion of the light-emitting diode so that the light-emitting portion of the light-emitting diode cannot be seen from a direction orthogonal to the linear array direction of the light-emitting diode in a plane including the optical axes of the light-emitting diodes A linear light source device characterized by the above. The light emitting diode array is arranged in two stages, and in the light emitting diode array in one stage, the angle θ ₁ formed by the optical axis of the light emitting diode with respect to the linear array direction of the light emitting diode is 0 ° <θ _1. <90 °, and the angle θ ₁ formed by the optical axis of the light emitting diodes with respect to the linear arrangement direction of the light emitting diodes is 90 ° <θ ₁ <180 °. The line light source device according to claim 5, wherein the line light source device is within a range. Angle θ in the one-stage light emitting diode array ₁ And the angle θ in the light emitting diode array of the other stage ₁ The line-shaped light source device according to claim 6, wherein the difference between and is in a range of more than 60 ° and less than 120 °. In an apparatus for inspecting a defect in the inspection object by irradiating the inspection object with light emitted from a line-shaped light source device, and detecting light that has passed through the inspection object,
The line light source device is a line light source device according to any one of claims 5 to 7,
A defect inspection apparatus comprising light detection means for detecting light passing through the inspection object and outputting a detection signal. The inspection object is set such that an angle θ ₂ formed by a plane including the optical axes of the plurality of light emitting diodes in the light emitting diode array with respect to the surface of the inspection object is in a range of 0 ° <θ ₂ <60 °. 9. The defect inspection apparatus according to claim 8, further comprising inspection object moving means for moving an object.

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