JP3096807B2 - Front / back discrimination method and front / back discrimination device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate in which the optical properties of edges are different between a front surface and a back surface, for example, a press punched plate. The present invention relates to a discrimination method and a front / back discrimination device used for implementing the method.

[0002]

2. Description of the Related Art There is a difference between the front surface and the back surface of a press-punched plate due to the punching process at the edge portion at the tip. That is, the front edge is more rounded than the rear edge. Such a punched plate is used as a link plate of a chain for a conveyor, and when assembled without distinguishing the front surface and the back surface, the quality of a completed chain is deteriorated. Therefore, there is a method of chamfering or engraving only one side of the plate in order to distinguish between the front surface and the back surface of the press punched plate, visually inspecting the presence or absence of the chamfer or engraving, and discriminating the front and back.

In the case of this method, the discrimination accuracy varies depending on the inspector or the degree of fatigue of the inspector. In addition, this method requires a chamfering or engraving step, which is complicated. Also, it takes a considerable amount of time to determine by visual inspection, so when inspecting an object flowing at a constant interval on a belt conveyor, this inspection process becomes a time constraint for a series of processes including this. Problem.

[0004] Instead of a visual inspection by a human, there is a method in which the surface of the plate is imaged by a CCD camera, and the engraved mark is detected by image recognition to determine the front and back sides. In the case of this method, the problem of the discrimination accuracy and the discrimination time caused by the inspector is solved, but the discrimination accuracy is greatly affected by the depth of the stamp, the warpage of the plate, and the oil stain.
Lack of reliability.

[0005]

Generally, the optical properties of a rounded edge portion and a sharp edge portion are different. The inventor of the present invention has found that the difference between the front surface and the back surface, which the press punched plate originally has, can be detected as a difference in optical properties, and that this feature is used for discrimination between front and back surfaces. The present invention has been made in view of such circumstances, and a method of determining the front and back of a board by determining the optical properties of the edge by image recognition from a captured image of the edge of the board to determine the front and back of the board and the implementation thereof. The purpose is to provide a front / back discrimination device to be used.

[0006]

Front and back discrimination method Means for Solving the Problems] According to the first invention is a front and back discriminating method test object optical properties of the edge portion of each at the front and back are different, double the captured image
The number of judgment areas is determined, and the bright area in each judgment area is determined.
Is determined in advance the length of the threshold, and imaging the edge portion by irradiating light to the edge portion of the test object, each determination region of a captured image
The length of the light area in the area exceeds the threshold value respectively
It is characterized by determining whether or not the inspection target is the front surface or the back surface from a plurality of determined results .

[0007]

[0008]

[0009] sides discriminating apparatus according to the second invention, Oite the front and back discriminating apparatus for discriminating the front and back of the inspection object from the captured image obtained by capturing an image of a test object, and means for determining the determination area in the captured image, in the determination area Means for determining a threshold for the length of the light area, means for irradiating the edge of the inspection target with light,
Means for imaging the edge portion, determines the means for measuring the length of the bright region in the determine the constant region of the captured image, whether or not the length exceeds the pre-Symbol threshold, the determined result Means for determining whether the inspection target is the front surface or the back surface.

FIG. 1 is a schematic diagram of a front / back discrimination device of the present invention. In the figure, reference numeral 3 denotes a belt conveyor, which conveys an oblong punching plate 1 to be inspected placed thereon at a constant speed. Above the transfer area of the belt conveyor 3, a CCD camera 2 is provided so as to image the edge of the leading end of the punching plate 1 from the front of the edge downstream in the transfer direction. The scanning line direction of the CCD camera 2 is made to coincide with the transport direction of the belt conveyor 3. The CCD camera 2 is connected to a front / back determination unit 7 composed of a computer, which analyzes a captured image to determine the front / back of the inspection target.

A light source 4 for illuminating the imaging range of the CCD camera 2 is provided upstream of the CCD camera 2 in the transport direction of the belt conveyor 3. A surface light source is used as the light source 4.
Further, a pair of sensors 5a and 5b are provided at positions where the tip of the punching plate 1 can be detected in the vicinity of the center of the imaging range of the CCD camera 2. Detection signals from the sensor pairs 5a and 5b are transmitted to a control unit (not shown). The control unit receives the detection signals from the sensor pairs 5a and 5b, causes the light source 4 to emit light, and
The CCD camera 2 captures an image of the edge of the tip of the camera.

FIG. 2 is an explanatory diagram showing an example of a captured image. In the figure, reference numeral 11 denotes a plane area of the punched plate 1,
It has the shape of the letter “D”. On the left side (upstream in the transport direction) of the curved portion “D” of the plane region 11, there is a crescent-shaped bright region 12 along the left side. The light area 12 is the illuminated punching plate 1 of the light source 4 installed on the left side of the drawing.
Are generated by the reflected light at the edge of the tip of the punching plate, and serve as a basis for discriminating the front and back of the punching plate 1. On the right side (downstream in the transport direction) of the curved portion "D" of the plane area 11, there is a dark area 13 surrounding the area. The dark area 13 is generated by the shadow of the edge illuminated by the light source 4. All areas on the right side of the dark area 13 are background areas 31.

The picked-up image is picked up such that the bright area 12 at the edge of the tip of the punching plate 1 required for discrimination between the front and back faces fits in the CCD camera 2 and the positional relationship between the sensor pair 5a and 5b as described above. . Then, the plane area 11,
Straight lines that cross the bright area 12, the dark area 13, and the background area 31 are determined in the front / back determination unit 7 as determination lines A, B, and C, respectively, as illustrated.

FIG. 3 is a sectional view showing the path of a light beam incident on the CCD camera 2 at any one of the judgment lines. 3 (a) and 3 (b) show cross sections of a rounded edge portion and a sharp edge portion at a judgment line, respectively. FIG. 3A shows the path of the light beam when the edge portion is rounded. Reflected at the edge as shown
The light source of the light beam incident on the CCD camera 2 exists radially as viewed from the edge portion. That is, in the image captured by the CCD camera 2, incident light from a relatively wide range appears as a bright area.

FIG. 3B shows the path of a light beam when the edge portion is sharp. As shown in the figure, the light source of the light beam reflected on the edge portion and incident on the CCD camera 2 exists in a direction opposite to the CCD camera 2 horizontally and also in a direction opposite to the vertical direction when viewed from the edge portion. That is, in the image captured by the CCD camera 2, only the incident light from each of the above directions appears as a bright area.

Therefore, if the edge is rounded for discrimination between the front and back, reflected light at the edge is generated.
When the light enters the CCD camera 2 and the edge is sharp, the position of the light source 4 is determined so that the reflected light at the edge does not enter the CCD camera 2.

FIG. 4 is a sectional view showing an arrangement area of the light source. The light source 4 that satisfies the above-described conditions is located between the light source positions of the light rays that are reflected at the nearest end of the edge of each surface forming a sharp edge and are incident on the CCD camera 2. . In the figure, the light source arrangement area is shown by diagonal lines. That is, by arranging the light source 4 in this arrangement region, the properties of the edge portion can be inspected from the area of the bright region 12 generated by the reflected light of the light source 4 to determine the front and back sides.

The outline of the front / back discrimination criteria for discriminating between front and back with the rounded surface of the edge to be inspected as the front will be described. By arranging the light source 4 as described above, the nature of the edge portion appears as the width of the bright region 12 on the determination line. That is, the width of the bright portion area on the edge determination line is longer in the rounded front than in the back.

FIG. 5 is an explanatory diagram showing a threshold value of the width of the bright area 12 in the judgment line in the captured image. This threshold value is determined based on experience. That is, the light area 12
Are evaluated in three stages, and the stage with the shortest width is determined as the back, the next unknown and the stage with the longest width are determined as the table. A plurality of determination lines are provided, and determination is performed independently for each line, and the front and back sides are comprehensively determined from the respective determination results. For example, when three determination lines are provided, if all the determination results of the three determination lines are front (or back), it is determined to be front (or back). If two of the determination results of the three determination lines are front (or back) and the remaining one is unknown, it is determined to be front (or back). Other combinations of the determination results are determined to be unknown.

[0020]

FIG. 6 is a block diagram of a front / back discrimination device according to the present invention. In the figure, reference numeral 41 denotes a light source for illuminating an imaging target. The light source 41 emits light when supplied with electricity from the light source power supply. The light source power supply 42 is connected to a control unit 70 using a computer, and thereby receives on / off control of a current supplied to the light source 41. The control unit 70 further includes a CCD camera 20 for imaging the imaging target, a tip detection sensor 50 for detecting that the imaging target has entered the imaging range of the CCD camera 20, and blowing off oil adhering to the surface of the imaging target. Nozzle 61 for injecting air for the air and a pressure sensor 62 for detecting the air pressure are connected. Also,
A monitor 10 for displaying a captured image is connected.

Upon receiving a detection signal from the tip detection sensor 50, the control unit 70 first activates the air nozzle 61 to blow off oil adhering to the surface of the object to be imaged. A command to open the shutter of the CCD camera 20 is issued in synchronization with the light emission of 41. Then, the obtained captured image is displayed on the monitor 10, the front and back of the imaging target are determined from the captured image, and the determination result is output.

FIG. 7 is a flowchart showing the discriminating process in the control unit 70. First, an image is captured (S1), the width of the bright portion of the determination line A is measured from the captured image (S2), and the front and back sides are determined (S3). Also, the width of the bright portion of the determination line B is measured from the captured image (S4), and the front and back sides are determined (S5). Also, the width of the bright portion of the determination line C is measured from the captured image (S6),
The front and back are determined (S7). The determination of each determination line is performed independently. At the stage where the determination of all the determination lines is determined, the front and back are determined according to the majority logic as described above (S
8).

[0023]

As described above, in the case of the present invention, chamfering or engraving is performed by discriminating the front and back of the inspection object having different optical properties of the respective edges on the front and back based on the properties of the reflected light at the edges. eliminates the need for steps performing, moreover Ki out to obtain a practical determination results to eliminate the problems caused by the inspector, further shorten the processing time required for determination while maintaining the reliability of the front and back of the discrimination result can do.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a front / back discrimination device of the present invention.

FIG. 2 is an explanatory diagram illustrating an example of a captured image.

FIG. 3 is a cross-sectional view of a path of a light beam incident on a CCD camera.

FIG. 4 is a cross-sectional view illustrating an arrangement region of a light source.

FIG. 5 is an explanatory diagram showing a threshold value in a bright portion area of a determination line.

FIG. 6 is a block diagram of a front / back discrimination device of the present invention.

FIG. 7 is a flowchart of a discrimination process of the front / back discrimination device of the present invention.

[Explanation of symbols]

 Reference Signs List 1 stamping plate 2, 20 CCD camera 4, 41 light source 7 front / back determination unit 50 tip detection sensor 70 control unit

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Takayuki Morimoto 4-17-96, Tsurumi-ku, Tsurumi-ku, Osaka City, Osaka Inside Tsubakimoto Chain Co., Ltd. (56) References JP-A-63-142836 (JP, A) JP-A-4-86512 (JP, A) JP-A-2-21247 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/84 G01B 11/26

Claims (2)

(57) [Claims] 1. A method for determining the front and back sides of an inspection object having different optical properties of an edge portion between a front surface and a back surface, wherein a plurality of determination regions are defined in a captured image, and
That the bright region is determined in advance the length of the threshold, and imaging the edge portion by irradiating light to the edge portion of the test object, the length of the bright region occupying the respective determination area of the captured image, respectively The threshold
A method for determining whether the inspection object is a front surface or a back surface from a plurality of determined results . 2. A front and back discriminating device for discriminating the front and back of the inspection object from the captured image obtained by capturing an image of a test object, means and the length of the threshold value of the bright region in the determination region defining the determination area in the captured image hand as stipulated the
Hand measuring the stage, and means for irradiating light to the edge portion of the test object, and means for imaging the edge portion, the length of the bright region in the determine the constant region of a captured image
Determining the stage, whether the length exceeds the pre-Symbol threshold was determined
Front and back discrimination instrumentation for said object from results is characterized in that it comprises a means for determining which one of the front or back surface
Place .