JP2005214720A - Surface inspection device and surface inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple surface inspection device capable of specifying the type of the surface flaw of an object to be inspected. <P>SOLUTION: The surface inspection device is equipped with light sources 10 and a light detector 11. The light sources 10 are provided on the plane crossing the surface 3a of the object 3 to be inspected and arranged in a semicircular state so that the angles to the surface 3a are respectively differentiated. The light detector 11 is provided so as to form a predetermined angle with respect to the plane on which the light sources 10 are arranged. The light sources 10 illuminate an inspection region 3b in a state that an illumination condition is changed and the light detector 11 detects a part of an irregular reflection component or a regular reflection component in illumination reflected light. A surface pattern is formed on the basis of the light detection data acquired at every illumination condition to be compared with a preliminarily recorded flaw pattern. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface inspection apparatus and method, and more particularly to an apparatus and method for inspecting defects appearing as surface irregularities and shading information of an object to be inspected such as a sheet-like object.

  In the conventional surface defect inspection, an inspection object is illuminated with a light source, and this is imaged with a camera, and the presence / absence or size of a surface defect is determined based on this imaging data. For example, in the surface defect detection method of Patent Document 1, the positional relationship among the light source, the inspection object, and the camera is relatively changed so that the illumination incident angle at each position on the inspection object surface continuously changes. However, for a plurality of images with different irradiation incident angles obtained continuously by the camera, the distribution of the regular reflection illumination incident angles when the illuminance at the same point is maximum is obtained for all the detection object surface points, Next, an angle distribution image showing the distribution of the regular reflection illumination incident angle is obtained, the angle distribution image is determined, and the inclination of the surface at every position on the surface of the inspection object is measured with a simple device configuration.

  In addition, in the surface defect inspection apparatus of Patent Document 2, in order to detect surface defects such as irregularities on the painted surface of the body of an automobile, a gate-shaped shape surrounding the object to be inspected and a predetermined light and dark pattern on the object to be inspected are provided. Surface defects are inspected using the illumination means to be formed and a plurality of imaging means that form a portal shape surrounding the object to be inspected and create a received light image based on the reflected light of the object to be inspected.

  In the surface defect inspection apparatus disclosed in Patent Document 3, the inspection object is illuminated from different angles, and the defect appearing in the first image obtained by imaging the inspection object at the first light angle and the second light angle. In comparison with the defect appearing in the second image obtained by imaging the object to be inspected, it is determined whether the defect is a true defect or a pseudo defect.

Japanese Patent No. 3312849 Japanese Patent No. 3204443 Japanese Patent No. 3012602

  However, in the above conventional inspection apparatus, since the defect is determined based on whether or not the detection level of the defect exceeds a predetermined threshold value, the type of defect cannot be specified even if the presence or absence of the defect can be determined. There is. In order to specify even the defect type, it is necessary to individually set a plurality of detection conditions for each defect type, and there is a problem that the facility becomes large.

  An object of the present invention is to provide a simple surface inspection apparatus and method capable of specifying a defect type for a defect on a surface of an inspection object.

  The present invention relates to a surface inspection apparatus for inspecting a surface defect of an object to be inspected, and a plurality of illumination incident angles with respect to the surface are provided, and a light source that illuminates the surface at the time of lighting, and any of the plurality of light sources Illumination condition changing means for changing the illumination condition of the surface by turning on a light source, light receiving means for receiving reflected light of the illumination reflected on the surface, and acquired by the light receiving means each time the illumination condition is changed Surface information creation means for creating surface information of the surface based on light reception information, the created surface information, and defect information created for each defect type, which is information acquired in advance for a surface having a defect. And a defect discriminating means for discriminating the presence / absence of a defect and the type of defect on the surface.

  The light sources are preferably arranged in a semicircular shape on a plane that intersects the surface approximately at a right angle or at a constant angle.

  The light receiving means acquires a scattered component or a part of the regular reflection component of the reflected light as an electric signal, the light receiving information is S / N value information of the electric signal, and the surface information is the S / N value. It is preferable that the surface pattern information is obtained by arranging the S / N values in order of illumination conditions after classification according to the size, and the defect information is surface pattern information on a surface having a defect.

  The present invention relates to a surface inspection method for inspecting a surface defect of an object to be inspected, and by changing an illumination condition by turning on an arbitrary light source among a plurality of light sources provided with different illumination incident angles on the surface. The surface information is generated by illuminating the surface, receiving reflected light of the illumination reflected on the surface each time an illumination condition changes, and creating surface information of the surface based on light reception information acquired by light reception. And defect information created for each defect type, which is information acquired in advance for a surface having a defect, and the presence / absence of a defect on the surface and the type of defect are determined.

  According to the present invention, a plurality of illumination incident angles with respect to the surface of the object to be inspected are provided, and a light source that illuminates the surface at the time of lighting and an arbitrary light source among the plurality of light sources are lit to turn on the surface. Illumination condition changing means for changing illumination conditions, light receiving means for receiving reflected light of the illumination reflected on the surface, and light reception information acquired by the light receiving means each time the illumination condition is changed, The surface information creating means for creating the surface information, the created surface information, and the defect information created for each defect type which is information acquired in advance for the surface having a defect, Since it has defect determination means for determining the presence / absence of a defect and the defect type, it is possible to specify the defect type of a defect generated on the surface of the inspection object with a simple structure.

  According to the present invention, the illumination condition is changed by turning on an arbitrary light source among a plurality of light sources provided with different illumination incident angles with respect to the surface. The reflected light of the illumination reflected on the surface is received, the surface information of the surface is created based on the received light information obtained by light reception, and the created surface information and the surface having a defect are acquired in advance. Compares the defect information created for each defect type with information and determines the presence or absence of the defect on the surface and the defect type, so the defect type of the defect generated on the surface of the inspection object can be identified with a simple structure can do.

  As shown in FIG. 1, the surface inspection system 2 includes a transport device 4 that transports the inspection object 3 on a horizontal plane, and a surface inspection device 5 that inspects a defect on the surface 3 a of the inspection object 3. The inspection object 3 is a sheet-like object in which defects are caused by scratches, coating unevenness, deposits, and the like on the surface 3a, such as a photosensitive lithographic printing plate, a photosensitive sheet, and a steel plate.

  The transport apparatus 4 includes a transport table 9 to which the inspection object 3 is fixed, and a drive mechanism (not shown) that displaces the transport table 9 in a two-dimensional direction on a horizontal plane. The inspection object 3 fixed to the conveyance table 9 together with the conveyance table 9 is conveyed on the horizontal plane by driving the drive mechanism, and the entire surface of the inspection object 3 can be inspected.

  The surface inspection apparatus 5 includes a plurality of light sources 10 and a light receiver 11. The plurality of light sources 10 are provided on a plane perpendicular to the surface 3a of the inspection object 3 set on the transport table 9, and illuminate the inspection region 3b of the surface 3a of the inspection object 3. The plurality of light sources 10 are provided in a semicircular shape with different angles with respect to the surface 3a. For this reason, the illumination incident angle on the inspection region 3b differs depending on each light source. The illumination incident angles are 5, 25, 45, 65, 90, 115, 135, 155, and 175 degrees from the one located on the left in FIG. An LED is used as the light source 10. As the light source 10, a known device such as a strobe or a halogen lamp may be used instead of the LED. In the vicinity of each light source, a condenser lens 12 is provided corresponding to each light source, and the light emitted from each light source is converted into parallel light by the condenser lens 12 to illuminate the inspection region 3b. The light source 10 is operated and turned on by a light source operating unit 15 (see FIG. 3) described later.

  As shown in the side view of FIG. 2, one light receiver 11 is provided so as to form a predetermined angle with respect to a plane on which the plurality of light sources 10 are arranged in a semicircular shape. In FIG. 2, the light sources other than the light source provided at the top of the plurality of light sources 10 are not shown. Although the area type CCD camera is used for the light receiver 11, any other light receiving sensor may be used as long as it can perform photoelectric conversion. Since the light receiver 11 is provided so as to form a predetermined angle with respect to the plane on which the plurality of light sources 10 are arranged, a part of the irregular reflection component in the reflected light from the inspection region 3b can be received. it can. Further, depending on the surface state of the inspection region 3b, a part of the regular reflection component of the reflected light may be received. The reflected light is composed of a regular reflection component and an irregular reflection component.

  As shown in FIG. 3, the light source operating unit (illumination condition changing means) 15 receives a command signal from the control unit 16 and operates a predetermined light source among the plurality of light sources 10 to light it. When receiving the instruction signal from the control unit 16, the light source operating unit 15 first turns on the light source located on the leftmost side in FIG. The light sources are turned on sequentially for each light source in the clockwise direction in FIG. The lighting is performed only for a short time.

  The control unit 16 controls the driving of the transport device 4 and the driving of the light source operating unit 15 and the light receiver 11. The control unit 16 drives the light source actuating unit 15 and the light receiver 11 after driving the conveyance device 4 to stop the inspection object 3 at a predetermined position.

  The light receiver 11 receives a part of the irregular reflection component or the regular reflection component of the reflected light and converts it into an electric signal. The electrical signal acquired for each illumination condition is sent to the surface pattern creation unit (surface information creation means) 17 via the signal processing unit 20. The signal processing unit 20 averages the signal of each pixel corresponding to the inspection region 3b. Note that, by operating an external operation input device (not shown), the optimum range of the inspection area 3b is set according to the type of the inspection object 3 and the type of defect to be inspected. The surface pattern creation unit 17 calculates an S / N value based on the transmitted electrical signal. The S / N value is high when the level of the electric signal is large, and is low when the level of the electric signal is small.

  The surface pattern creation unit 17 classifies the S / N value into four levels according to the magnitude of the value, and adds a symbol for each level. Then, these symbols are arranged in the order of illumination conditions to form an array. This arrangement becomes the surface pattern. Details will be described later. The detected surface pattern is sent to the defect determination unit 18 as surface pattern information.

  The defect discriminating unit 18 compares the detected surface pattern with the defect pattern. The defect pattern is acquired in advance before the inspection, and is a surface pattern when there is a defect. A defect pattern is created for each defect type. When the detected surface pattern matches any of the defect patterns, it is determined that there is a defect of this defect pattern type in the inspection region 3b of the inspection object 3. On the other hand, when the detected surface pattern does not match any of the defect patterns, it is determined that there is no defect in the inspection region 3b of the inspection object 3. A specific example will be described later. The monitor 19 displays the determination result.

  Hereinafter, the operation of the above configuration will be described. The surface inspection system 2 divides the surface 3a of the inspection object 3 into a plurality of inspection areas, and inspects each inspection area. When changing the inspection area, the transport device 4 is driven, and the inspection object 3 moves on the horizontal plane.

  When driving of the conveying device 4 is stopped and a predetermined region of the surface 3a of the inspection object 3 is defined as the inspection region 3b, lighting is started from the light source located at the leftmost in FIG. Lights up in the clockwise order in FIG. In this way, the illumination conditions change. The inspection region 3b is irradiated with parallel light, and of the reflected light from the inspection region 3b, the irregular reflection component or a part of the regular reflection component is acquired by the light receiver 11 and converted into an electric signal.

  The surface pattern creation unit 17 calculates an S / N value for each illumination condition based on the transmitted electrical signal. In the surface pattern creation unit 17, as shown in Table 1, if the S / N value is less than 1.5, x, if it is 1.5 or more and less than 2.5, Δ, if it is 2.5 or more and less than 4.0. If there is, the symbol ○ is added if it is 4.0 or more. These symbols are arranged in the order of illumination conditions and recorded as a detected surface pattern. Note that the criteria for determining these classifications may be changed as appropriate in accordance with the type of the inspection object 3 and the type and size of the inspection target defect. The number of classifications may be changed as appropriate.

  The detected surface pattern is compared with the defect pattern by the defect determination unit 18. The defect patterns to be compared are shown in Table 2. When the detected surface pattern matches one of the defect patterns from the defect A to the defect F, it is determined that there is a defect of the same defect pattern type in the inspection area 3b. On the other hand, when the detected surface pattern does not match any defect pattern from the defect A to the defect F, it is determined that there is no defect in the inspection region 3b. In this way, the presence / absence of a defect and the type of defect in the inspection region 3b can be determined.

  Defects are caused by unevenness and color unevenness. In particular, when it is desired to determine a defect due to color unevenness, a light source that emits light having a predetermined wavelength corresponding to the color unevenness is used.

  Information on the presence / absence of a defect in the inspection region 3b and the determined defect type is output to the monitor 19. Thereafter, an allowable defect and an unacceptable defect determination (OK / NG determination) may be performed according to the type of defect. For example, regarding a defect A and a defect B that increase in S / N value only when a light source with an illumination incident angle of 90 degrees is turned on, the defect A may be determined to be NG, and the defect B may be determined to be OK.

  When the inspection of the inspection area 3b is finished, the conveying device 4 is driven to convey the inspection object 3, and the surface inspection of the uninspected inspection area is performed. When the entire surface area of the specimen 3 is inspected, the inspection operation is completed.

  In the above-described embodiment, since the light source 10 is repeatedly turned on and off sequentially from the leftmost light source in FIG. 1, the illumination is performed by one light source. Alternatively or additionally, any light source may be turned on simultaneously. For example, adjacent light sources may be turned on simultaneously, or every other light source or every other light source may be turned on simultaneously. By doing in this way, illumination conditions can be increased further and the discrimination | determination precision of defect discrimination | determination can be raised.

  In the above embodiment, the plurality of light sources 10 are provided on a plane that intersects the surface 3a of the object 3 at a right angle. Instead, a plurality of light sources 10 are provided on a plane that intersects the surface 3a at an arbitrary angle. Also good. When this angle is the same as the angle at which the light receiver 11 is provided and is opposed to the vertical surface of the surface 3a (that is, as shown in FIG. 4), the light receiver 11 is It is possible to positively acquire a regular reflection component and use information based on the regular reflection component for later determination. In this way, the regular reflection component may be positively acquired during irradiation of some light sources. When actively acquiring a regular reflection component, it is preferable in terms of design to use an LED ring illumination as a light source and dispose the light receiver 11 at the center of the LED ring illumination.

  In the above embodiment, the plurality of light sources 10 are provided on one plane that intersects the surface 3a of the inspection object 3 at right angles. However, the light sources are provided by being dispersed on a plurality of planes that intersect the surface 3a at an arbitrary angle. Also good. Furthermore, the plurality of light sources 10 may be arranged in an arbitrary shape without being limited to a semicircular shape.

  In the above embodiment, the surface pattern creation unit 17 calculates the S / N value for each illumination condition based on the electrical signal and creates the surface pattern based on the S / N value, but instead. Alternatively, the electrical signal may be recorded as a surface pattern as it is, and the defect type may be determined by pattern matching processing with the surface pattern previously obtained for each defect type.

  In the above embodiment, the defect type information or the like is output to the monitor 19, but in addition to this, the inspection area position information from the transfer device 4 and the defect type information or the like are recorded in a memory or the like in correspondence with each other. An image or data indicating the defect position and defect type may be output to the printer.

  In the said embodiment, the defect inspection apparatus 5 was fixed and the show thing 3 was moved on the horizontal surface. Instead, the inspection object 3 may be fixed and the defect inspection apparatus 5 may be moved on a horizontal plane.

It is a front view which shows the outline of a surface inspection apparatus and a to-be-inspected object. It is a side view which shows the outline of a surface inspection apparatus and a to-be-inspected object. It is a block diagram which shows the electrical outline of a surface inspection apparatus. It is a side view which shows the outline of the surface inspection apparatus in another embodiment, and a to-be-inspected object.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Surface inspection system 3 Inspected object 3a Surface 3b Inspection area 5 Surface inspection apparatus 10 Light source 11 Light receiver (light receiving means)
15 Light source operating part (lighting condition changing means)
16 control unit 17 surface pattern creation unit (surface information creation means)
18 Defect determination unit (defect determination means)
20 Signal processor

Claims (4)

In the surface inspection device that inspects the surface defect of the inspection object,
A plurality of illumination incident angles with respect to the surface are provided, and a light source that illuminates the surface during lighting,
Illumination condition changing means for changing the illumination condition of the surface by turning on an arbitrary light source among the plurality of light sources;
A light receiving means for receiving reflected light of the illumination reflected on the surface;
Surface information creating means for creating the surface information of the surface based on the light reception information acquired by the light receiving means each time the illumination condition is changed,
A defect that determines the presence or absence of a defect and the type of defect on the surface by comparing the created surface information with defect information that has been acquired in advance for a surface having a defect and is created for each defect type A surface inspection apparatus comprising: a determination unit.   2. The surface inspection apparatus according to claim 1, wherein the light sources are arranged in a semicircular shape on a plane that intersects the surface substantially at a right angle or at a constant angle.   The light receiving means acquires a scattered component or a part of the regular reflection component of the reflected light as an electric signal, the light receiving information is S / N value information of the electric signal, and the surface information is the S / N value. 2. The surface pattern information in which the S / N values are arranged in order of illumination conditions after classification according to size, and the defect information is surface pattern information on a surface having a defect. Or the surface inspection apparatus of 2. In a surface inspection method for inspecting defects on the surface of an inspection object,
Illuminating the surface by changing an illumination condition by turning on an arbitrary light source among a plurality of light sources provided with different illumination incident angles on the surface, and reflected on the surface every time the illumination condition changes Receiving reflected light of illumination, creating surface information of the surface based on received light information acquired by light reception, and information acquired in advance for the created surface information and a surface having a defect, for each defect type A surface inspection method comprising comparing the defect information created in step 1 to determine the presence or absence of defects on the surface and the type of defect.

Images