CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Japanese application serial no. 2018-030930, filed on Feb. 23, 2018. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The present technology relates to an image inspection apparatus and an image inspection method for inspecting an object using a captured image.

Description of Related Art

In the field of factory automation and the like, capturing an image of an object while illuminating the object and inspecting the exterior of the object using the acquired captured image is known.

For example, Japanese Laid-Open No. 2017-62120 (Patent Document 1) discloses an inspection system using an illumination device including a surface light source, and a lens, a light-shielding mask and a filter disposed between the surface light source and an inspection target. In this system, a radiation solid angle of inspection light radiated to each point of the inspection target is formed approximately uniformly according to the lens, the light-shielding mask and the filter. Accordingly, a whole visual field can be uniformly radiated to improve object inspection accuracy.

According to the conventional method, it is necessary to previously identify a relative position of the illumination device with respect to an image capturing unit (camera) when an object is inspected. Accordingly, adjustment (calibration) for determining a relative position between the image capturing unit and the illumination device needs to be performed before the object is inspected. However, it is desirable that as little calibration as possible be necessary from the viewpoint of user convenience.

SUMMARY

According to this disclosure, an image inspection apparatus includes: an image capturing unit which captures images of an object; a transparent illumination unit which is disposed between the object and the image capturing unit, has a light-emitting surface which radiates light to the object and is configured to be able to control a light-emitting position on the light-emitting surface and a radiation direction of the light; and a control unit which is configured to control the image capturing unit and the illumination unit. The control unit causes the illumination unit to radiate light to the object in a first direction and causes the light to scan by changing the light-emitting position on the light-emitting surface in first scanning of the illumination unit, and causes the image capturing unit to capture images of the object during the first scanning. The control unit causes the illumination unit to radiate light to the object in a second direction different from the first direction and causes the light to scan by changing the light-emitting position on the light-emitting surface in second scanning of the illumination unit, and causes the image capturing unit to capture images of the object during the second scanning. The control unit identifies a light-emitting position of the illumination unit when a measurement point of the surface of the object is illuminated from images of the object captured during the first scanning and the second scanning, and calculates a distance to the measurement point on the basis of the identified light-emitting position, the first direction and the second direction.

