Inspection apparatus, inspection method, and program

Patent metadata

Field	Value
Publication number	US-9494528-B2
Application number	US-201514718113-A
Country	US
Kind code	B2
Filing date	May 21, 2015
Priority date	Jun 9, 2014
Publication date	Nov 15, 2016
Grant date	Nov 15, 2016

Abstract

To facilitate adjusting of a distance from an inspection target to an illumination section by providing a movable illumination section that is movable independently of the imaging section. An illumination apparatus has a plurality of LEDs arranged in a substantially annular form, a light diffusion member for diffusing light emitted from the plurality of LEDs, and a lighting control part for lighting the plurality of light sources in accordance with a predetermined lighting pattern when designated to start lighting. In particular, the illumination apparatus moves independently of a camera to adjust a distance to a workpiece.

First claim

What is claimed is:

1. An inspection apparatus comprising:
an imaging section configured to capture an image of an inspection target;
an illumination section which has a plurality of light sources arranged in a substantially annular form, a light diffusion member for diffusing light emitted from the plurality of light sources, and a lighting control part for lighting the plurality of light sources to illuminate the inspection target from three or more illumination directions in accordance with a predetermined lighting pattern when designated to start lighting, and which moves independently of the imaging section to adjust a distance to the inspection target;
a setting section configured to set a characteristic size which is a parameter showing a size of the surface shape of the inspection target;
an inspection image generating section configured to
a) synthesize a plurality of luminance images, acquired by the imaging section, by a photometric stereo method,
b) obtain an inclination data which has an inclination component of the surface shape of the inspection target based on a normal vector data of the surface of the inspection target computed from the synthesized plurality of luminance images, and
c) generate an inspection image having a plurality of pixel values in accordance with the inclination data of the surface of the inspection target based on the characteristic size set by the setting section; and
a determination section configured to determine defectiveness/non-defectiveness of the inspection target by using the inspection image.

2. The inspection apparatus according to claim 1 , wherein a shading member is arranged between two adjacent light sources out of the plurality of light sources.

3. The inspection apparatus according to claim 1 , wherein the illumination section has a first substrate on which the plurality of light sources are mounted, and a second substrate on which the lighting control part is mounted.

4. The inspection apparatus according to claim 1 , wherein the plurality of light sources are arranged in an annular form.

5. The inspection apparatus according to claim 1 , wherein
the illumination section further has a storage part in which a lighting pattern of the plurality of light sources is stored, and
the lighting control part lights the plurality of light sources in accordance with the lighting pattern stored in the storage part when designated to start lighting.

6. The inspection apparatus according to claim 1 , wherein
the plurality of light sources are connected in series, and
a switch capable of being switched on/off by the lighting control part is connected in parallel to each of the plurality of light sources.

7. The inspection apparatus according to claim 6 , further comprising
a variable power source for supplying a voltage to the plurality of light sources;
a variable constant current source for adjusting a current that flows through the plurality of light sources; and
a main switch for switching on/off of the variable constant current source,
wherein, after a voltage supplied by the variable power source becomes sufficiently high, the lighting control part switches the switch that is connected in parallel to each of the plurality of light sources in accordance with the lighting pattern, and switches on the main switch, to light any of the plurality of light sources in accordance with the lighting pattern.

8. The inspection apparatus according to claim 7 , wherein the lighting control part controls a voltage of the variable power source in accordance with a voltage value that is fed back from the variable constant current source such that an overvoltage is not applied to the variable constant current source.

9. The inspection apparatus according to claim 1 , wherein the
setting section sets a flaw inspection region for the inspection image; and the inspection apparatus further comprising
a flaw inspecting section for inspecting a flaw in the flaw inspection region,
wherein the determination section determines defectiveness/non-defectiveness of the inspection target based on a result of inspection by using the inspection image by the flaw inspecting section.

10. The inspection apparatus according to claim 1 , wherein the
setting section sets a character recognition region for the inspection image; and the inspection apparatus further comprising
a character recognizing section for recognizing a character in the character recognition region,
wherein the determination section determines defectiveness/non-defectiveness of the inspection target based on a result of recognition by using the inspection image by the character recognizing section.

11. The inspection apparatus according to claim 1 , further comprising
an adjustment section for adjusting a characteristic size which is a parameter that is required at the time of creating the inspection image.

12. The inspection apparatus according to claim 11 , wherein the inspection image generating section generates a plurality of inspection images based on respectively different characteristic sizes designated by the adjustment section.

13. The inspection apparatus according to claim 1 , wherein the inspection image generating section generates, as the inspection image, a surface shape image based on a normal vector of the surface of the inspection target or a texture image based on a reflectance of the surface of the inspection target.

14. An inspection method comprising the steps of:
capturing an image of an inspection target by an imaging section;
illuminating the inspection target by an illumination section when the imaging section captures the image of the inspection target, the illumination section having a plurality of light sources arranged in a substantially annular form, a light diffusion member for diffusing light emitted from the plurality of light sources, and a lighting control part for lighting the plurality of light sources to illuminate the inspection target from three or more illumination directions in accordance with a predetermined lighting pattern when designated to start lighting, and moving independently of the imaging section to adjust a distance to the inspection target;
setting a characteristic size which is a parameter showing a size of the surface shape of the inspection target;
synthesizing a plurality of luminance images, acquired by the imaging section, by a photometric stereo method, obtaining an inclination data which has an inclination component of the surface shape of the inspection target based on a normal vector data of the surface of the inspection target computed from the synthesized plurality of luminance images, and generating an inspection image having a plurality of pixel values in accordance with the inclination data of the surface of the inspection target based on the characteristic size set by said setting; and
determining defectiveness/non-defectiveness of the inspection target by using the inspection image.

15. A program which causes a computer to execute each of the steps according to claim 14 .

16. The inspection apparatus according to claim 1 , further comprising,
a display section configured to display the inspection images generated by the inspection image generating section, wherein
the inspection image generating section generates the plurality of inspection images by utilizing respectively different characteristic sizes,
the setting section includes an image selection section configured to select the inspection image among the plurality of the inspection images displayed on the display section and the characteristic size is se

Assignees

• Keyence Co Ltd

Inventors

• Matsuda Hajime

Classifications

• G01N21/8806 Primary

  Specially adapted optical and illumination features · CPC title

• G01N21/8851

  Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges (G01N21/8806 and G01N21/93 - G01N21/95692 take precedence; optical measurement of dimensions G01B11/00; optical scanning G02B26/10; image transformation G06T3/00; computerised image enhancement G06T5/00; image processing per se for flaw detection G06T7/0002) · CPC title

• G06T2207/10152

  Varying illumination · CPC title

• G06T2207/20016

  Hierarchical, coarse-to-fine, multiscale or multiresolution image processing; Pyramid transform · CPC title

• G01N2021/845

  Objects on a conveyor · CPC title