JPH06105170B2 - Appearance inspection machine - Google Patents

Description

The present invention relates to a visual inspection machine for detecting defects formed on the surface of an object to be inspected such as a printed wiring board.

[Prior Art] Conventionally, as an appearance detector for detecting a defect formed on the surface of an object to be inspected such as a printed wiring medium, as shown in FIG. The light is projected by the projector 2, and the surface of the inspection object 1 projected by the projector 2 is imaged obliquely from above by the imaging means 3 such as a TV camera arranged in front of the projector 2 and obtained by this imaging. The grayscale image data is digitally converted by the A / D converter 4 and stored in the frame memory 5, and the determination processing unit 6 compares the grayscale pixel density stored in the frame memory 5 with a predetermined threshold value to stain the Some have detected defects 7 such as irregularities, dents, and flaws. For example, in the case of a defect 7 such as unevenness, a dent, or a flaw that forms unevenness on the surface of the object to be inspected 1, the light projected by the projector 2 creates a shadow in the valley of the unevenness, and when it is captured as a grayscale image, The area of becomes a darker image than the other areas. Therefore, if this density is higher than the threshold value, it can be detected as the defect 7.

[Problems to be Solved by the Invention] By the way, in the conventional appearance inspection machine, since the one projector 2 projects light onto the object to be inspected 1 as described above, the direction of projection is unidirectional. In the defect 7 due to a dent like a mark, a shadow can be formed if the running direction of the valley of the dent intersects the projection direction a as shown in FIG. 3, but it may be a direction parallel to the projection direction b. If there is no shadow, defect 7 cannot be detected.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an appearance inspection machine capable of reliably detecting even a defect such as a dent.

[Means for Solving the Problems] The present invention relates to a projector for projecting light in the direction of an object to be inspected, an imaging means for imaging the surface of the object to be inspected projected by the projector from a position opposite to the projector, and an imaging device. In an appearance inspection machine equipped with an image processing means capable of detecting a defect on the surface of an object to be inspected from a grayscale image obtained by the means, the projection axis is oblique with respect to the conveyance direction of the object to be inspected, and A first projector for projecting light obliquely above the surface to the front in the transport direction;
A plurality of sets of first imaging means composed of a line sensor for capturing the surface of the inspected object projected by the projector of the above, and arranged in the width direction of the inspected object, and projecting in the conveying direction of the inspected object. A second projector in which the light projection axis is set so that the light axis is oblique and intersects the light projection axis of the first light projector, and the light is projected in a direction opposite to the conveying direction with respect to the surface of the inspection object; A plurality of sets of second image pickup means composed of line sensors for catching the surface of the object to be inspected projected by the second light projector are arranged in the width direction of the operated object. The surface of an object to be inspected is projected and imaged from multiple directions.

[Operation] Even if the direction of the valley of the defect formed by the dent is in any direction, a shadow due to the defect can be generated by any one of the light projectors, and the image pickup means corresponding to the light projector that generated this shadow can be used. Defects can be detected from the obtained gray-scale image, and in particular, defects due to dents such as dents occur on the surface of the object to be inspected, and the direction of the dent valleys is the direction of the light projection of the first and second light projectors. Even if the shadow is parallel to one side, a shadow can be generated in the other projection direction, and the shadow can be captured by the imaging means corresponding to the projector that has generated the shadow, and as a result, defect detection can be performed reliably. is there.

[Embodiment] FIG. 1 shows an image pickup means 3, 3'and a projector 2, according to an embodiment of the present invention.
2 ', the line sensor is used as the image pickup means 3, 3'in this embodiment, and the projection axis is oblique with respect to the conveyance direction of the inspection object 1 shown by the arrow A and the inspection object is inspected. A plurality of sets of a projector 2 for projecting light obliquely upward from the surface of the object 1 to the front in the transport direction and an image pickup means 3 for capturing the surface of the object 1 to be inspected projected by the projector 2 are provided. The object to be inspected is arranged in the width direction, and the light projecting axis is set so that the light projecting axis is oblique to the conveying direction of the object to be inspected 1 and intersects the light projecting axis of the light projector 2. A plurality of sets of a projector 2 ′ that projects light in an anti-conveyance direction from obliquely above the surface of 1 and an imaging means 3 ′ that captures the surface of the inspected object 1 projected by this projector 2 ′, the inspected object 1 Are arranged in the width direction of.

Thus, a defect due to a dent such as a dent occurs on the surface of the object 1 to be inspected, and even if the direction of the valley of the dent is parallel to one of the light projecting directions of the projector 2 or 2 ', the other projecting direction does not occur. A shadow can be produced, and the projector 2 or 2'that has produced this shadow
The shadow can be picked up by the image pickup means 3 or 3'corresponding to the above, and the defect can be surely detected.

Since the defect determination is performed with the same configuration as that of FIG. 2, the description of the configuration and operation will be omitted.

EFFECTS OF THE INVENTION The present invention can be obtained by a projector that projects light onto the surface of an object to be inspected, an imaging unit that images the surface of the object to be inspected projected by the projector from a position opposite to the projector, and an imaging unit. In an appearance inspection machine equipped with an image processing means for detecting defects on the surface of the object to be inspected from the grayscale image, the projection axis is oblique to the conveying direction of the object to be inspected and A plurality of sets of a first projector for projecting light obliquely from above to the front in the conveying direction and a plurality of first imaging means composed of a line sensor for capturing the surface of the object to be inspected projected by the first projector are provided. In addition to being arranged in the width direction, the projection axis is set so that the projection axis is oblique to the conveyance direction of the inspection object and intersects the projection axis of the first projector. A second projector for projecting light in a direction opposite to the surface and a second projector A plurality of sets of second imaging means composed of a line sensor for catching the surface of the object to be inspected, which are projected by the vessel, are arranged in the width direction of the operated object, and the object to be inspected by the projector and the imaging camera. Since the surface of an object is projected and imaged from multiple directions, a shadow can be generated by either projector regardless of the direction of the valley of the defect formed by the dent, and as a result, this shadow is generated. There is an effect that a defect can be detected by a grayscale image obtained by an image pickup unit corresponding to the generated light projector, and a directional defect that has been impossible to detect can be detected.

[Brief description of drawings]

FIG. 1 is an explanatory view of an arrangement state of an image pickup means and a light projector according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a conventional example, and FIG. 3 is an explanatory view of the same. Reference numeral 1 is an object to be inspected, 2, 2'is a projector, and 3, 3'is an image pickup means.

Claims (1)

[Claims] 1. A light projector for projecting light onto the surface of an object to be inspected, image pickup means for picking up an image of the surface of the object to be inspected projected by the light projector from a position opposite to the light projector, and a grayscale image obtained by the image pickup means. In an appearance inspection machine equipped with an image processing means for detecting defects on the surface of the object to be inspected, the projection axis is oblique with respect to the conveying direction of the object to be inspected, and obliquely above the surface of the object to be inspected. A plurality of sets of a first light projector that projects light forward in the transport direction and a first imaging unit that includes a line sensor that captures the surface of the object to be inspected projected by the first light projector are arranged in the width direction of the object to be inspected. With respect to the surface of the object to be inspected, the light emitting axis is set so as to be oblique with respect to the transport direction of the object to be inspected and intersect the light emitting axis of the first light projector. And a second projector for projecting light in the direction opposite to the transport direction, and the light projected by the second projector. The second plurality of sets of the imaging means comprising a line sensor for capturing the surface of the object to be inspected, the visual inspection device, characterized in that arranged in the width direction of the object to be inspected.