JPH05188006A - Surface flaw detecting device - Google Patents

Abstract

PURPOSE:To reduce the cost of facilities, reduce the time of photographing, detect the flow with high accuracy, and enable specifying of the shape and kind of the flow. CONSTITUTION:A surface flow detecting device is provided with light sources 1, 2, 3 of three primary colors of red, green and blue to irradiate the surface to be detected of an object, and a color camera 5 having RGB output functions, and also provided with an image processing part 6 which receives the signals of variable density of three kinds according to the respective primary colors from RGB output terminals 5a, 5b, 5c, achieves the image analyses, and detects the flow on the surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting flaws on the surface of an object such as a steel plate.

[0002]

2. Description of the Related Art Conventionally, when detecting a flaw on the surface of an object of this type, it is common to illuminate the flaw with general illumination and photograph the shadow to detect the presence or absence of the flaw.

Further, in the case of irradiating light, when the object which cannot be photographed by only irradiating from one direction or the image information after photographing is not sufficient, the necessary number of lights fixed at predetermined positions are provided one by one. It is also known that the lights are turned on in sequence and the image information is obtained by picking up images with a single camera each time.

Further, it is also known that several illuminating devices are installed so that light rays from different angles do not interfere with each other, and an image is taken by a camera paired with each illuminating device. In this case, for example, when irradiating from three directions, three lighting devices are installed at intervals so that light beams do not interfere with each other, or a shielding plate is installed between adjacent lighting devices. , 3 cameras that are paired with each lighting device will be used for shooting.

On the other hand, in Japanese Unexamined Patent Publication No. 3-105239, when detecting flaws on the surface of a rolled product, there are three primary colors of white light.
Of the three colors of red, green, and blue, light of any two colors can be
It proposes to irradiate the surface of the rolled product with the remaining one color of light from the opposite side, photograph this with a camera, and display it on a color monitor. In this case, the normal part without any unevenness is white, but the flawed part with unevenness appears as if the flawed part was colored due to the shading effect of the unevenness, making it easier to find the flawed part.

[0006]

However, the method of sequentially photographing the irradiation light from a plurality of light sources with one camera is time-consuming and cannot be used for online processing. Further, the method of photographing with a plurality of light sources and a camera paired with each other is costly. Moreover, since both of them use general illumination light, it is difficult to specify the shape and type of the flaw. For example, in the case of a minute flaw, depending on the irradiation direction, the surface properties of the plate and the reflection method of light. In some cases, the image cannot be captured at all.

On the other hand, although the technique of the above-mentioned publication is recognized to be effective for flaw detection, the flaw detection accuracy is not high, the flaw shape cannot be detected accurately, and it is extremely unsuitable for specifying the type of flaw. It is enough.

Therefore, an object of the present invention is to reduce the equipment cost by taking an image with a single camera in terms of cost, to shorten the taking time, to detect a flaw with high accuracy, and The purpose is to be able to specify the shape and type of the flaw.

[0009]

SUMMARY OF THE INVENTION The above-mentioned problems are solved by the following three primary color light sources of red, green and blue for illuminating the detection surface of an object, one color camera having an RGB output function, and its RGB output terminals. The problem can be solved by including an image processing unit that takes in three types of grayscale image signals corresponding to each primary color, analyzes the image, and detects a flaw on the surface.

[0010]

According to the present invention, as will be described later, since the image is taken by one camera, the equipment cost is reduced. Further, since it is basically sufficient to take an image at the time of simultaneous irradiation from each light source, it is suitable for online processing. Moreover, since the three types of grayscale image signals corresponding to the respective primary colors are fetched from the RGB output terminals, flaws can be reliably detected.

[0011]

The present invention will be described in more detail with reference to a representative embodiment shown in FIG. In the present invention, the red illumination 1, the green illumination 2, and the blue illumination 3 are installed at appropriate positions with respect to the detection site on the surface of the object 4. In this case, the lighting 1, 2, 3
If all three are not in the same direction, their installation locations are not limited, and for example, two of them may be the same.

An image of the surface of the object 4 thus irradiated is picked up by one color camera 5 having an RGB output function. Accordingly, the red component emitted by the red illumination 1 is the red element 5A, the green component emitted by the green illumination 2 is the green element 5B, and the blue component emitted by the blue illumination 3 is the blue element 5C. Each is detected as a grayscale image.

These grayscale image signals are taken out from the RGB output terminals 5a, 5b, 5c and taken into the image processing circuit section 6, and the true flaw shape and size are taken out by the OR processing. E.g. C
It is displayed on the RT display device 7 or the like and used for flaw inspection.
If necessary, the feature type of the flaw shape and size may be input to the neural network or other signal processing may be performed to determine the flaw type.

As described above, when general illumination is used, in the case of minute flaws, depending on the irradiation direction, it may not be possible to take an image at all due to the surface texture of the plate, the way of reflecting light, and the like.
However, according to the present invention, as shown in FIG. 3A, for example, although it is not possible to monitor from the R output (irradiation direction of red illumination), it is possible to monitor from the G output and B output (irradiation direction of green illumination and blue illumination). Therefore, even if it is a slight flaw, the detection can be surely performed.

Further, by taking out signals from the RGB output terminals 5a, 5b, 5c and subjecting the image processing circuit unit 6 to an OR operation, as a result, as shown in FIG. 4, the true flaw shape and size are obtained. Can be detected.

FIG. 2 shows another example in which two sets of three primary color illuminations are provided, that is, red illuminations 1A and 1B and green illumination 2 are provided.
This is an example in which A, 2B and blue illuminations 3A, 3B are provided.

In this case, in the first irradiation,
The red light 1A, the green light 2A, and the blue light 3A are irradiated to capture the first image, and the second light is irradiated to the red light 1B, the green light 2B, and the blue light 3B to capture the second image. , A total of 6 grayscale images are obtained. Therefore, a large number of grayscale images can be obtained in a short time.

[0018]

As described above, according to the present invention, the equipment cost can be reduced and the photographing time can be shortened. Further, it becomes possible to detect the flaw with high accuracy and to specify the shape and type of the flaw.

[Brief description of drawings]

FIG. 1 is an overall view of a first example of a device of the present invention.

FIG. 2 is a schematic diagram of another example.

FIG. 3 is an explanatory diagram of an example of a grayscale image that can be obtained from RGB output terminals.

FIG. 4 is an explanatory diagram of an example of a grayscale image that can be obtained from RGB output terminals and an image obtained after signal processing.

[Explanation of symbols]

1 ... Red illumination, 2 ... Green illumination, 3 ... Blue illumination, 4 ... Color camera, 5 ... Object, 6 ... Image processing circuit section.

Claims (1)

[Claims] 1. A red, green, and blue primary color light source for illuminating a detection surface of an object, a color camera having an RGB output function, and three types of primary colors from RGB output terminals thereof. A surface flaw detection apparatus comprising an image processing unit that takes in a grayscale image signal and analyzes the image to detect flaws on the surface.