JPH06175199A - Lighting and image pickup device - Google Patents

Abstract

PURPOSE:To provide a lighting and image pickup device capable of accurately picking up the rugged shape of engraved characters, etc., formed on a surface even in the case the reflectance of an image to be picked up is different. CONSTITUTION:This lighting and image pickup device provided with a lighting means 14 for lighting the image to be picked up 10 and an image pickup means 24 for picking up the image to be picked up 10 which is lightened by the lighting means 14 has a polarizing means 22 for polarizing the light which is emitted from the lighting means 14 to the image 10 to be picked up and also for polarizing the light which is reflected on the image 10 to be picked up toward the image pickup means 24 and a polarizing direction rotating means 26 for rotating the polarizing direction of the polarizing means 22. The image 10 to be picked up is picked up by the image pickup means 24 while the polarizing direction of the polarizing means 22 is rotated by the polarizing direction rotating means 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination image pickup device for illuminating and picking up an image of an object to be imaged, and more particularly to illumination for illuminating an image of an object to be imaged having irregularities such as engraved characters formed on its surface. The present invention relates to an imaging device.

[0002]

2. Description of the Related Art When capturing an image of an object having an uneven shape such as an engraved character on the surface of a metal part, the object is illuminated by an illumination light source and reflected from the surface of the object. The captured image is captured by the image capturing camera. By adjusting the intensity of the illumination by the illumination light source and adjusting the aperture of the imaging camera according to the characteristics such as the reflectance of the metal part to be imaged, various images of the object can be displayed with appropriate brightness and contrast. Take an image. By imaging the metal component with appropriate brightness and contrast in this manner, it is possible to accurately image the uneven shape of the stamped characters and the like formed on the surface.

[0003]

However, when the reflectivity differs depending on the material of the metal part which is the object to be imaged, the optimum brightness and contrast differ depending on the reflectivity, so that the strike formed on the surface of the metal part is different. There is a problem that it is not possible to accurately capture the uneven shape such as engraved characters. In addition, there is a problem in that the uneven shape of the stamped characters and the like formed on the surface of the metal part varies, so that the polarization state of the reflected light reflected from the uneven surface changes and the uneven shape cannot be accurately imaged. It was

An object of the present invention is to provide an illumination image pickup capable of accurately picking up an uneven shape such as an embossed character formed on the surface even if the reflectance of the material of the object to be imaged or the reflection angle due to the uneven shape is different. To provide a device.

[0005]

The above-described object is to provide an illumination image pickup apparatus having illumination means for illuminating an object to be imaged, and image pickup means for imaging the object to be imaged illuminated by the illumination means. From the object to be imaged, and polarizing light from the object to be imaged to the imager, and polarization direction rotating means for rotating the polarization direction of the polarizing means. The illumination image pickup device is characterized in that an image of the object is picked up by the image pickup means while rotating the polarization direction of the polarization means by the polarization direction rotation means.

[0006]

According to the present invention, the illumination light from the illumination means to the object to be imaged is polarized, and the reflected light from the object to be imaged to the imager is polarized, and the polarization direction of the polarizing means is rotated. A polarization direction rotating means is provided, and the object to be imaged is imaged by the image capturing means while rotating the polarization direction of the polarizing means by the polarization direction rotating means. Even if the uneven shape of the engraved characters or the like changes, the uneven shape of the embossed characters or the like formed on the surface can be accurately imaged.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An illumination image pickup device according to a first embodiment of the present invention will be described with reference to FIGS. In this embodiment, a metal part, which is an object to be imaged, is illuminated and imaged, and the stamped characters formed on the surface are matched with a standard pattern stored in advance to detect a defect in the metal part.

The metal component 10 which is the object to be imaged is conveyed by the component conveying device 12. In this embodiment, the metal component 1
As the material of No. 0, a mixture of a galvanized steel plate and a non-zinc plated steel plate is used. The galvanized steel sheet has a low reflectance, and the non-galvanized steel sheet has a high reflectance. A ring-shaped fiber illuminator 14 is provided for illuminating the metal component 10. The ring-shaped fiber illumination 14 and the illumination light source device 16 are connected by a fiber cable 18, and the ring-shaped fiber illumination 1
A large number of fibers are arranged in a ring shape on the light emitting surface of No. 4. The light generated by the illumination light source device 16 is emitted from the light emission surface of the ring-shaped fiber illumination 14 via the fiber cable 18.

In this embodiment, a polarizing plate 22 is provided between the half mirror 20 and the metal part 10 which is the object to be imaged, and the light emitted from the light emitting surface of the ring-shaped fiber illumination 14 is emitted by the half mirror 20. Is reflected by the polarizing plate 22 and is converted into linearly polarized light by the polarizing plate 22 to illuminate the metal component 10. A CCD camera 24 is provided behind the half mirror 20. The light reflected by the metal component 10 passes through the polarizing plate 22 and the half mirror 20 and enters the CCD camera 24.
The CCD camera 24 images the reflected light from the metal component 10 which is transmitted through the polarizing plate 22 again and converted into linearly polarized light.

The polarizing plate 22 is a polarizing plate that converts transmitted light into linearly polarized light. The polarizing plate 22 is attached at an angle α downward from a plane perpendicular to the optical axis of the illumination light, and reflects the illumination light to the object 10 in a direction displaced from the CCD camera 24 to directly reflect the illumination light. The light is prevented from entering the CCD camera 24. It should be noted that the polarization plate 22 may be arranged in any position, such as tilted upward as opposed to FIG. 1, as long as the illumination light to the object 10 can be reflected in a direction deviated from the CCD camera 24.

The polarizing plate 22 is rotated about the optical axis of the illumination light by the polarizing plate rotation driving unit 26. The polarizing plate rotation drive unit 26 is driven and controlled by the polarizing plate rotation drive control unit 28. Details of drive control will be described later. The image processing device 30 captures an image captured by the CCD camera 24, performs image processing described below, and detects a defect in the metal component 10 from an embossed character formed on the surface of the metal component.

It should be noted that the material of the conveyed metal component 10 and the component data such as written characters are sent to the image processing apparatus 30 from a host computer (not shown). The image processing device 30 determines a defect of the metal component 10 based on the transmitted component data. Next, the defect determination operation of the illumination image pickup device according to the present embodiment will be described with reference to FIGS.

When the metal component 10 is conveyed by the component conveying device 12 and reaches the image pickup position, the metal component 10 is stopped at the image pickup position. While illuminating the metal component 10 with the ring-shaped fiber illumination 14, the polarization plate rotation driving unit 26 rotates the polarization plate 22, and the CCD camera 24 images the surface of the metal component 10. The image of the contour of the stamped character on the metal component 10 changes depending on the rotational position of the polarizing plate 22. That is, the contour of the engraved character of the metal component 10 has a portion that strongly shines depending on its position and becomes indistinguishable from the surroundings, but the shining portion gradually shifts depending on the rotation angle of the polarizing plate 22. The present embodiment utilizes such a phenomenon to accurately capture an imprinted character.

FIG. 2 shows a concrete example. In this specific example, "8"
The imprinted character is imaged. The right side of FIG. 2 shows the angular position (arrow) of the polarizing plate 22, and the left side shows the captured image. The left side of the captured image is the image before binarization, and the right side is the image after binarization. The white portion of the polarizing plate 22 indicates the portion where the captured image becomes bright.
The polarizing plate 22 is rotated so that the direction (arrow) of the linearly polarized light changes from the position of 0 degree (FIG. 2A) to the position of 45 degrees (FIG. 2A).
(A)), a 90 degree position (FIG. 2 (a)), and a 135 degree position (FIG. 2 (a)). It can be seen that the bright portion of the contour of the stamped character of the metal component 10 moves according to the rotation of the polarizing plate 22. On the contrary, it can be said that the portion where the contour of the embossed character is clearly imaged moves according to the rotation of the polarizing plate 22.

In the present embodiment, the polarizing plate rotation drive control unit 28
The metal component 10 is imaged at different angular positions while the polarizing plate 22 is rotated by, and the plurality of captured images are averaged (arithmetic mean or geometric mean) by the image processing device 30. Figure 2
The averaged captured images of (a) to (d) are shown in FIG. The left side of FIG. 3 is the image before binarization, and the right side is the image after binarization.

As shown in FIG. 2, a part of the contour of the embossed character is missing at each angular position, but if the captured images are averaged, the contour of the embossed character will be as shown in FIG. It is possible to obtain a captured image that is not missing. In FIG. 4, FIG.
(D), the captured images of FIG. 3 are shown side by side. It can be seen that the imaged image at each angular position lacks a part of the outline, but in the averaged imaged image, the defect of the outline is corrected and a complete embossed character is obtained.

The image processing device 30 matches the written character pattern sent from the host computer (not shown) with the averaged picked-up image, and if the match is found, it is judged as a good product, and if not matched, it is a defective product. Is determined as. The image processing device 30 is a CCD camera 24.
Before the image is picked up by the amplifier, the gain of the amplifier and the A / D are adjusted by the material information sent from the host computer (not shown).
Change the offset of the converter. For example, in the case of a material with high reflectance such as ungalvanized steel plate,
Reduce the gain of the amplifier and the offset of the A / D converter. On the contrary, in the case of a material having a low reflectance such as a galvanized steel plate, the gain of the amplifier and the offset of the A / D converter are increased. As a result, even if the reflectance of the material is different, it is possible to always obtain a captured image of appropriate brightness without adjusting the brightness of the ring-shaped fiber illumination 14 or the aperture of the CCD camera 24.

Instead of the material information from the host computer (not shown), the gain of the amplifier and the offset of the A / D converter are automatically calculated based on the brightness of the ground portion of the object to be imaged 10. It may be changed. An illumination image pickup apparatus according to the second embodiment of the present invention will be described with reference to FIG. The same components as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, instead of the ring-shaped fiber illumination, two line-shaped fiber illuminations 40a and 40b are used. Two line fiber illuminations 40a, 40b
Are arranged in parallel above the metal part 10. The half mirror 20 in the first embodiment is not provided. The CCD camera 24 has two linear fiber illuminations 40a and 40b.
The metal part 10 is imaged from between.

The light emitted from the light emitting surfaces of the linear fiber illuminators 40a and 40b is converted into linearly polarized light by the polarizing plate 22 and illuminates the metal component 10. The light reflected by the metal component 10 passes through the polarizing plate 22, is converted again into linearly polarized light, and is incident on the CCD camera 24. In this embodiment,
By uniformly illuminating a metal part that is long in the direction perpendicular to the paper surface of FIG. 5, it is possible to accurately capture an image of the uneven shape of an embossed character or the like formed on the surface.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, although the stamped characters on the surface of the metal component are imaged in the above-mentioned embodiment, the stamped characters are not limited to the stamped characters and may be any characters, marks or the like as long as they have an uneven shape. Further, although the metal component is imaged in the above-described embodiment, an imaged object made of another material such as plastic may be used.

Further, although the polarizing plate is used in the above embodiment, other polarizing means may be used without being limited to the polarizing plate. As the polarization direction rotating means, one suitable for the polarizing means used may be used.

[0023]

As described above, according to the present invention, the polarization means for polarizing the illumination light from the illumination means to the object to be imaged and the light reflected from the object to be imaged to the image pickup means, and the polarization means. And a polarization direction rotating means for rotating the polarization direction of the image pickup device is provided, and the object to be imaged is imaged by the image pickup device while rotating the polarization direction of the polarization device by the polarization direction rotating device. Moreover, even if the reflection angle due to the uneven shape of the embossed character or the like is different, the uneven shape of the embossed character or the like formed on the surface can be accurately imaged.

[Brief description of drawings]

FIG. 1 is a diagram showing an illumination image pickup apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a specific example of a captured image of the illumination imaging device shown in FIG.

FIG. 3 is a diagram showing a specific example of a captured image of the illumination imaging device shown in FIG.

FIG. 4 is a diagram showing a specific example of a captured image of the illumination imaging device shown in FIG.

FIG. 5 is a diagram showing an illumination image pickup apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Metal parts 12 ... Parts conveying device 14 ... Ring fiber illumination 16 ... Illumination light source device 18 ... Fiber cable 20 ... Half mirror 22 ... Polarizing plate 24 ... CCD camera 26 ... Polarizing plate rotation drive unit 28 ... Polarizing plate rotation drive control 30 ... Image processing device 40a, 40b ... Line fiber illumination

Claims (2)

[Claims] 1. An illumination image pickup apparatus comprising: an illumination unit that illuminates an object to be imaged; and an image capturing unit that images the object to be imaged illuminated by the illumination unit, wherein illumination from the illumination unit to the object to be imaged. A polarizing unit that polarizes the light and that polarizes the reflected light from the object to be imaged to the imaging unit, and a polarization direction rotating unit that rotates the polarization direction of the polarizing unit, is provided by the polarization direction rotating unit. An illumination image pickup device, wherein the image pickup means picks up an image of the object to be picked up while rotating a polarization direction of a polarizing means. 2. The illumination image pickup apparatus according to claim 1, further comprising image averaging means for averaging a plurality of picked-up images of different polarization directions of the polarization means.