JP2009222614A - Surface inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the surface inspection accuracy when an irregular part such as a long groove exists in the surface of a workpiece. <P>SOLUTION: A line fiber illumination 10 is arranged so as to be orthogonal to the irregular part We of the workpiece W, the reflected light from the workpiece W is made to come into a line sensor camera 11, and an image signal is obtained. Regularly reflected light from the line fiber illumination 10 decreases on a tilting surface of the irregular part We, so that a plurality of small fiber illuminations 14 and 15 are disposed on both sides of the line fiber illumination 10, light is radiated from a diagonal direction, and the surface inspection by uniform illumination is performed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface inspection apparatus for inspecting foreign matters and coating defects adhering to a resin, glass, or metal object to be measured having uneven portions such as long grooves on the surface.

  Conventionally, when inspecting using a line sensor, in order to uniformly illuminate the surface of an object, as disclosed in Patent Document 1, a large number of LEDs are arranged so that uniform light is applied to the surface of the object to be measured. The configuration is known.

JP 2003-202294 A

  However, the inspection target surface has long grooves and peaks in the direction orthogonal to the longitudinal direction of the illumination, and the inspection target having a strong gloss such as glass or mirror is from the surface perpendicular to the optical axis of the line sensor. However, the reflected light is weak on the slopes such as grooves. Therefore, there is a problem that a uniform video signal cannot be obtained in the entire inspection region.

  An object of this invention is to provide the surface inspection apparatus which can perform the surface inspection of the to-be-measured object which has uneven | corrugated | grooved parts, such as a groove | channel and a mountain, on the surface with high precision.

  The surface inspection apparatus of the present invention is a surface inspection apparatus that inspects the surface of an object to be measured having a concavo-convex portion, a first light source that makes first inspection light incident on the surface of the object to be measured, and the object to be measured. A second light source that makes the second inspection light incident on the surface of the measurement object from an oblique direction, and a detection that detects the reflected light reflected by the measurement object with respect to the first and second inspection lights. Means, an image processing device for processing an image of the object to be measured based on the output of the detecting means, and the first light so that the reflected light from the uneven portion and the remaining surface of the object to be measured is uniform. And a control means for controlling the relative position and the light quantity of the second light source, respectively.

  By independently controlling the first light source that irradiates the planar portion of the object to be measured and the second light source that irradiates the slope of the uneven portion such as a groove, the entire object is irradiated with a uniform amount of light. An image signal of an object can be obtained. Therefore, the defect can be detected under uniform conditions over the entire surface.

  The best mode for carrying out the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a surface inspection apparatus for detecting the surface of a workpiece W having a concave and convex portion We such as a long groove on the surface is arranged on the workpiece W so as to be orthogonal to the length direction of the concave and convex portion We. Line fiber illumination 10 and a line sensor camera 11 as detection means. In addition, the image processing apparatus 12 includes an image processing device 12 that performs image processing on signals from the line sensor camera 11, and a computer 13.

  The line fiber illumination 10 that is a first light source is configured to irradiate the surface of the workpiece W with the first inspection light that is long in the direction parallel to the line sensor camera 11. Placed on top.

  On both sides of the line fiber illumination 10, small fiber illuminations 14 and 15 as a pair of second light sources are arranged. The fiber illuminations 14 and 15 make the second sensor light incident from an oblique direction so that the reflected light regularly reflected by the inclined surface of the uneven portion We of the object to be measured W enters the line sensor camera 11. 11 are arranged symmetrically with respect to the optical axis.

  The light amount of the line fiber illumination 10 and the fiber illuminations 14 and 15 on both sides thereof can be adjusted independently. Further, a plurality of the fiber illuminations 14 and 15 are arranged on a straight line in the length direction of the line sensor camera 11, and the arrangement angle and the like can be adjusted independently.

  Uniform light (inspection light) for inspecting the surface of the object W to be measured by controlling the relative position such as the light amount and angle of the line fiber illumination 10 and the fiber illuminations 14 and 15 by the computer 13 which is a control means. Can be irradiated.

  The fiber illuminators 14 and 15 are light sources that emit parallel rays, and illuminate the normal of the slope of the concavo-convex portion We of the object to be measured W from an angle symmetric to the optical axis of the line sensor camera 11.

  Conventionally, the surface to be inspected has long grooves and peaks in the direction perpendicular to the longitudinal direction of the illumination, and the surface to be orthogonal to the optical axis of the line sensor camera is inspected with a high gloss such as glass or mirror. The reflected light from was strong, but the reflected light was weak on the slope of the inspection object. As a result, there is a problem that a uniform video signal cannot be obtained in the entire inspection area. The present invention solves such problems and can detect defects under uniform conditions over the entire surface to be inspected, so that it is possible to improve detection sensitivity for defects with small changes in light quantity.

  1 to 3 illustrate the first embodiment. The object to be measured W is an elongated member having a plurality of long grooves or mountain-shaped uneven portions We on the surface. The line sensor camera 11 is arranged in a direction perpendicular to the length direction of the object to be measured W, has an imaging lens 11a, and displays an image of the surface of the object W to be inspected on the line sensor camera 11. Make an image. The line fiber illuminator 10 is arranged at a position where the light emitted from the line fiber illuminator 10 is regularly reflected at the top or bottom of the flat portion of the object to be measured W or a mountain or groove and enters the imaging lens 11a. Has been.

  Each of the pair of small fiber illuminators 14 and 15 is provided with a lens at the tip of the fiber and generates light having strong directivity. The line fiber illuminator 10 and a plurality of small fiber illuminators 14 and 15 arranged on both sides of the optical axis of the line sensor camera 11 are separately provided with luminance controllers 17, 18 and 19, and control illumination luminance and the like independently. it can. The image signal from the line sensor camera 11 is input to the image processing device 12, and the signal from the line sensor camera 11 is signal-processed as a two-dimensional image, so that the state of the surface of the workpiece W can be detected. The detected signal is output to the computer 13 and communicated to a host production line controller (not shown).

  As shown in FIG. 2, the surface of the workpiece W to be inspected has not only a flat plane portion but also slopes at the peaks and grooves of the uneven portion We. Since the regular reflection light R1 at the plane portion reflects the incident light L1 perpendicularly incident on the plane portion, a bright image signal can be obtained by using illumination such as coaxial epi-illumination. However, at the peak or groove, only the regular reflection light Re from only a part such as the top of the peak or the bottom of the groove can provide the same reflection as the plane. Therefore, the signal waveform obtained when only line-shaped illumination is used is as shown in the graph A1 of FIG. 3A. Although a bright signal is obtained in the leftmost plane portion, specular reflection light is obtained at the slope. It is dark because there is no. In this state, if there is a defect on the slope portion to be inspected, the detection signal is small, so that the defect detection capability is also small.

  Accordingly, the incident light L2 from the fiber illuminations 14 and 15 illuminates the inclined surface from both the left and right sides of the groove and the like, and the regular reflected light R2 on the inclined surface is incident on the imaging lens 11a. Thereby, the signal by the light reflected by the slope as shown by graphs A2 and A3 in FIG. Graph A2 is a line sensor signal waveform when only the left fiber illumination 14 is turned on, and graph A3 is a line sensor signal waveform when only the right fiber illumination 15 is turned on. Therefore, by using all the illuminations from the three directions and adjusting the light amounts, angles, etc. of the three light sources, uniform reflected light can be obtained over the entire inspection object as shown in the graph A4 in FIG. To control. In this way, a detection signal with uniform conditions can be obtained.

  Here, for example, when there is a foreign substance as shown by C in FIG. 2 on the surface to be inspected, the regular reflected light is blocked by the foreign substance, so that a line sensor signal waveform as shown in FIG. 3B is obtained. The graph B1 is a waveform when only the line fiber illumination 10 is used, the graph B2 is a waveform when only the left fiber illumination 14 is used, and the graph B3 is a line when only the right fiber illumination 15 is used. It is a sensor signal waveform. If all the illuminations from three directions are used, only the foreign substance C is dark as shown in the graph B4, and the other non-defective parts can obtain image signals with uniform brightness, so that the foreign substance detection capability is improved.

  In addition, when the arrangement | positioning of Fig.1 (a) is seen from a side surface, as shown in (b), the line fiber illumination 10 is on the optical axis and target position of the line sensor camera 11 with respect to the perpendicular of the plane to be examined. The specular reflection light enters the imaging lens 11a. Moreover, since the small fiber illuminations 14 and 15 arranged on both sides of the line fiber illumination 10 are arranged at positions where the regular reflection of the inclined surface to be inspected enters the imaging lens 11a, the angle is larger than that of the line fiber illumination 10. It is arranged in.

  Moreover, the angle of each of the small fiber lights 14 and 15 with a lens can be independently adjusted by a fixing means (not shown). This may be fixed to the cylinder at an arbitrary angle, or may be fixed with high accuracy using a rotary stage or the like. Then, the angle is set so that the irradiated light beam having directivity is regularly reflected by the inspection object and efficiently enters the imaging lens 11a.

  The second line fiber illumination 20 is installed in a position where regular reflection light does not enter the imaging lens 11a. This is a light source for detecting a scattered object present on the surface to be inspected as a bright image signal.

  FIG. 4 shows a second embodiment. In the present embodiment, the parallel light sources 34 and 35 that irradiate the workpiece W with parallel light are illuminated from the left and right instead of the plurality of small fiber illuminations 14 and 15 of the first embodiment. This light is regularly reflected by the slope of the uneven portion We of the object to be measured W, enters the imaging lens 11a, and forms an image on the line sensor camera 11.

  Even in this configuration, as in the first embodiment, even when there are long grooves or peaks in the direction orthogonal to the longitudinal direction of the line illumination on the surface to be inspected and the gloss is strong like a glass or a mirror, the inspection region A signal having a uniform light amount level can be obtained throughout. Since defects can be detected under uniform conditions, it is possible to improve detection sensitivity for defects with small changes in light quantity.

  FIG. 5 shows a third embodiment. In the present embodiment, the object to be measured W is illuminated from the left and right by the point light sources 44 and 45. The point light sources 44 and 45 are arranged at a distance from the inspection target and the light source so that the illumination angle can be considered constant throughout the entire inspection range. The light from the point light sources 44 and 45 is regularly reflected by the inclined surface of the uneven portion We of the object to be measured W, enters the imaging lens 11a, and forms an image on the line sensor camera 11.

  Even in this configuration, as in the first embodiment, the surface of the inspection object has a long groove or mountain in the direction orthogonal to the longitudinal direction of the line illumination, and even an inspection object having a high gloss such as a glass or a mirror is inspected. A signal having a uniform light amount level can be obtained over the entire area. Since the defect can be detected under uniform conditions, it is possible to improve the detection sensitivity for a defect with a small change in the amount of light.

FIG. 2 shows Example 1, (a) is a view showing an optical system of a surface inspection apparatus, and (b) is a view of (a) as viewed from the side. It is a figure explaining reflection of inspection light to a concavo-convex part to be examined. The line sensor camera output is shown. (A) is a graph for explaining the line sensor signal waveform of the normal part, and (b) is a graph for explaining the line sensor signal waveform when a foreign substance is present. 6 is a diagram illustrating an optical system of Example 2. FIG. 6 is a diagram illustrating an optical system according to Example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Line fiber illumination 11 Line sensor camera 11a Imaging lens 12 Image processing apparatus 13 Computer 14, 15 Fiber illumination 34, 35 Parallel light source 44, 45 Point light source

Claims (3)

In a surface inspection apparatus for inspecting the surface of an object to be measured having an uneven portion,
A first light source for causing the first inspection light to enter the surface of the object to be measured;
A second light source for causing the second inspection light to enter the surface of the object to be measured from an oblique direction;
Detecting means for detecting reflected light obtained by reflecting the first and second inspection lights by the object to be measured;
An image processing device for processing an image of the object to be measured based on the output of the detection means;
Control means for controlling the relative positions and the light amounts of the first and second light sources so that the reflected light from the uneven portion and the remaining surface of the object to be measured is uniform. Surface inspection device characterized by.   The surface inspection apparatus according to claim 1, wherein the first light source includes line fiber illumination, and the second light source includes a plurality of fiber illuminations.   The surface inspection apparatus according to claim 1, wherein the uneven portion has a plurality of grooves.

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