JPH0553204B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION This invention relates to an apparatus for inspecting empty cans, and more particularly to an apparatus for automatically inspecting the shape of a flange at the open end of an empty can.

Conventional technology and its problems For example, empty cans used for canning food have an integrally formed outward flange at the open end, and after filling the can with contents, the flange is connected to the periphery of the can lid. The can is sealed by tightening. In such a can, it is normal for the flange 1a of the empty can to be flat and perpendicular to the body portion 1b as shown in Figure 3a, as shown in Figure 3a, but as shown in Figure 3b.
There is also an abnormal case in which the entire or part of the flange 1a is curved, as shown in c. If the shape of the flange 1a is defective in this way, poor joining will occur during can manufacturing and when tightening the flange 1a, making it difficult to maintain airtightness and causing oxidation or leakage of the contents. Yes, especially in the case of food, which is unfavorable from a sanitary standpoint. Conventional can inspection devices include those that inspect the characters, patterns, or colors printed on the lid or body of a can to determine the quality of the printing, and those that determine the presence or absence of foreign matter inside the can. ,
There is nothing to judge the quality of the flange of an empty can. For this reason, conventionally, empty cans are supplied to canning manufacturing lines without flange inspection, but problems such as those described above can occur due to poor flange shape, and automation of inspection is desired. There is.

An object of the present invention is to provide a device that can automatically and accurately inspect empty cans as described above.

Means for Solving the Problems The empty can inspection device according to the present invention is a device for inspecting the quality of the shape of the flange at the open end of an empty can, and is a device for inspecting the shape of a flange at the open end of a plurality of empty cans. a ring-shaped illumination device disposed horizontally above the moving path of the empty can; and a television positioned downwardly above the illumination device for imaging the flange of the empty can through the inside of the illumination device. It is equipped with a camera and a processing device that determines whether the shape of the flange is good or bad based on the television image of the flange.The lighting device and the television camera are arranged so that the light reflected by a normal flange does not directly enter the television camera. , the television camera has a shutter function synchronized with a vertical synchronization signal in a composite video signal representing a television image, the lighting device is equipped with a light source that is turned on at a power supply frequency synchronized with the vertical synchronization signal, and the processing The device determines that the shape of the flange is defective when a particularly bright area appears in the television image of the flange.

Effect If the flange of an empty can has a normal shape, the light irradiated onto the flange by the ring-shaped lighting device will be reflected uniformly, and the reflected light will not directly enter the TV camera, so the flange will appear in the TV image. The area becomes relatively dark and uniformly bright. If the shape of the flange is defective, light will diffusely reflect at that part and enter the TV camera directly, making the TV image in that part brighter. Then, the quality of the shape of the flange is determined by checking whether there is a portion of the flange in the television image that has a brightness higher than a certain level. That is, just by taking an image of the flange of an empty can once with a television camera, the quality of the shape of the flange can be automatically and accurately inspected.

Further, since the television camera has a shutter function synchronized with the vertical synchronization signal in the composite video signal representing the television image, and the lighting device is equipped with a light source that is turned on at a power frequency synchronized with the vertical synchronization signal, Blurring of the TV image due to the movement of empty cans can be suppressed.

Embodiment FIG. 1 schematically shows the configuration of an empty can inspection device.

The empty can 1 has a cylindrical shape, and an outward flange 1a is integrally formed at the open end thereof. Third
The figure shows the flange 1a of the empty can 1.
Figure 1 shows a good product in which the flange 1a is perpendicular to the body portion 1b and is flat, and Figures b and c show defective products in which the flange 1a is curved in whole or in part.

Empty cans 1 are placed on the conveyor 10 with the open end facing up, and are placed one after another at a certain interval or more.
It is continuously moved to the right side of FIG.

An illumination device 11 using a ring-shaped light source is placed directly above the moving path of the empty cans 1 on the conveyor 10, and a television camera 12 is placed directly above the illumination device 11 facing downward. The inner diameter of the lighting device 11 is larger than the outer diameter of the flange 1a of the empty can 1, and the lighting device 11 uniformly illuminates the flange 1a of the empty can 1 located directly below it (hereinafter referred to as the inspection position) from the surroundings. irradiate. In addition, the lighting device 11 is installed so that the light is not directly irradiated onto the bottom of the empty can 1 that has arrived at the inspection position.
The dimensions and vertical position of are determined.
Also, check the normal flange 1 of the empty can 1 that has come to the inspection position.
The vertical position of the television camera 12 is determined so that the light reflected by the flat surface a does not directly enter the television camera 12. And the lighting device 11
Flange 1a of empty can 1 that has come to the inspection position on the inside
The outer part is arranged to be in the field of view of the television camera 12. A ring-shaped light shielding plate 13 is arranged directly above the light source of the lighting device 11. This light shielding plate 13 is for preventing unnecessary light from the lighting device 11 from entering the television camera 12. A transparent glass plate 1 is placed inside the light shielding plate 13.
4 is extended, and a short cylindrical light shielding member 15 is fixed to the center thereof in a downwardly protruding manner. This light shielding member 15 is connected to the flange 1a on the opposite side of the empty can 1 from which the light emitted from the illumination device 11 reaches the inspection position, and the body portion 1.
This is to prevent it from reaching the boundary portion 1c of b. If the light shielding member 15 is not provided, a part of the light emitted from the lighting device 11 to the opposite boundary portion 1c may be diffusely reflected and directly enter the television camera 12. The light shielding member 15 prevents this. The television camera 12 images the flange 1a of the empty can 1 that has come to the inspection position through the transparent glass plate 14, and generates a composite video signal a representing the television image.
is sent to the processing device 16.

Empty cans 1 are placed on the moving path of the empty cans 1 on the conveyor 10.
A can detector 1 detects that the has arrived at the inspection position.
7 is placed. For example, a photoelectric switch or a proximity switch is used as the can detector 17, and its output signal, that is, the can arrival signal b, is sent to the processing device 16 and the defective product rejecting device 18.

The processing device 16 uses the composite video signal a from the television camera 12 and the can arrival signal b from the can detector 17 as input signals to determine the quality of the flange 1a of the empty can 1 that has arrived at the inspection position, and to identify defective products. When detected, a defective product detection signal c is output to the rejecting device 18. The processing device 16 also includes a power supply section 19 of the lighting device 11.
A synchronization signal d is output to synchronize the operation timing of the lighting device 11 with the operation timing of the television camera 12.

Next, first, an outline of the quality determination of the flange 1a will be briefly explained.

Figure 4 shows the flange 1a of the empty can 1 that has come to the inspection position.
FIG. 5 shows a composite video signal a on one horizontal scanning line A of this television image. FIG. 4a shows the case of a non-defective product, and since the light reflected by the flange 1a does not directly enter the television camera 12, the flange 1a portion of the television image is relatively dark and its brightness is uniform. Therefore, the composite video signal a on the horizontal scanning line A is the fifth
As shown in Figure a, the signal level is relatively low even in the portion G corresponding to the flange 1a. FIG. 4b shows the case of a defective product in which a part of the flange 1a is curved, and a part of the light diffusely reflected by the defective part directly enters the television camera 12, so the flange 1a in the television image
A particularly bright portion N appears in a portion of a. Therefore, the composite video signal a on the horizontal scanning line A is as shown in FIG.
The signal level becomes high at the portion N corresponding to the bright portion N of the flange 1a. Then, no matter where on the flange 1a a particularly bright portion N is located, the signal level of the video signal a becomes high at the corresponding portion N without fail during one field in which the television screen is vertically scanned once. Therefore, by comparing the video signal a of one field of the television screen while the empty can 1 is at the inspection position with a threshold value V that is slightly higher than the signal level of the video signal a in the case of a non-defective product, the quality can be determined. can be done.

Processing device 16 for making the above determination
A specific configuration is shown in FIG.

Next, based on this, the operation of the processing device 16 will be explained in more detail.

A composite video signal a from the television camera 12 is sent to an amplifier 20 and a synchronization signal detector 21. amplifier 2
At 0, the DC component in the video signal a is reproduced and the amplitude is adjusted, and the output signal f is sent to the voltage comparator 22. The comparator 22 compares the signal f with a predetermined threshold value e, and detects a binary signal g that is high level when the signal f is larger than the threshold value and low level otherwise. output to the device 23. On the other hand, the synchronization signal detector 21 detects the video signal a
A vertical synchronizing signal d is extracted from the pulse generator 24 and sent to the pulse generator 24 and the power supply section 19. Pulse generator 2
4 is one field of the television screen from the vertical synchronizing signal d immediately after the empty can 1 arrives at the inspection position to the next vertical synchronizing signal d, based on the vertical synchronizing signal d and the can arrival signal b from the can detector 17. A signal i with a corresponding pulse width is generated and outputted to the defective product detector 23. The defective product detector 23 receives a signal i and a binary signal g.
A signal h is generated by calculating the logical product of , and outputs the signal h to the determination circuit 25 . Then, the determination circuit 25
A defective product detection signal c is generated, which goes to H level when the signal h rises and goes to L level when the can arrival signal b falls, and outputs it to the rejecting device 18.

In the case of a non-defective product, as described above, the amplitude of the signal f based on the video signal a of one field of the television screen immediately after the empty can 1 arrives at the inspection position does not exceed the threshold value e. Therefore, while signal i is at H level, signal g remains at L level. Therefore, while the can arrival signal b is at the H level, the signal h remains at the L level, and therefore the defective product detection signal c also remains at the L level. On the other hand, in the case of a defective product, as explained earlier, the signal f is always displayed during one field of the television screen immediately after the empty can 1 arrives at the inspection position.
becomes larger than the threshold e. Therefore, as shown in FIG. 8, the signal g always goes to the H level while the signal i goes to the H level. At the same time, the signal h also goes to H level, and the defective product detection signal c goes to H level until the can arrival signal b goes to L level. Therefore, while the can arrival signal b is at the H level, it can be determined that the product is good if the signal c remains at the L level, and it is determined that the product is defective if the signal c goes to the H level.

The rejecting device 18 rejects defective products from the conveyor 10 based on the can arrival signal b when the defective product detection signal c reaches H level. Note that this rejecting device 18 can be configured similarly to a conventional rejecting device for rejecting defective products at other inspection positions.

There are three methods for combining the light source of the lighting device 11 and the television camera 12: a method using a strobe light source and a normal television camera (the first method), a method using a television camera with a shutter function and a DC lighting light source (the first method); A second method) and a method using a television camera with a shutter function and an AC lighting light source (third method) can be considered, and the inspection device can be realized using either method. In the first method, the timing of strobe light emission may be made to coincide with the rise of signal i in FIG. 8, but it should be noted that strobe devices are generally expensive and the life of the lamp is short. In the second method, the television camera is more expensive than in the first method, and if a large amount of light is expected, an incandescent lamp is used as the light source, but ring-shaped incandescent lamps are difficult to obtain. In the third method, it is necessary to synchronize the operating timing of the television camera and the blinking timing of the light source, but it has the advantage that a commercially available fluorescent lamp can be used as the ring-shaped light source.

This invention employs the third method. Therefore, the television camera 12 has a shutter function synchronized with the vertical synchronization signal d in the video signal a. The power supply unit 19 has a function of lighting the light source of the lighting device 11 at a power frequency synchronized with the vertical synchronization signal d, and its specific configuration is shown in FIG.

Next, based on this, the operation of the power supply section 19 of the lighting device 11 will be explained in detail.

The pulse generator 26 of the power supply unit 19 generates an external trigger signal j that falls at the fall of the vertical synchronization signal d and rises after a set time τ, and outputs this to the DC/AC converter 27 . In addition, the converter 28
rectifies and smoothes the 100V AC power input m,
It outputs to the DC/AC converter 27. The DC/AC converter 27 converts the DC output l of the converter 28 into AC again, and when there is no external trigger signal, it uses a multivibrator that emits at about 60Hz to
An AC power supply output k of Hz and 100V is generated, and the frequency of the vertical synchronization signal d and the power supply output k are synchronized by forcibly triggering the multivibrator with an external trigger signal j. The set time τ of the external trigger signal j is used to align the brightest period of the lighting device 11 with the shutter open period of the television camera 12 (for example, immediately before or after each vertical synchronization signal d).

By doing so, the light source of the lighting device 11 is turned on at a power supply frequency synchronized with the vertical synchronization signal d, and blurring of the television image due to the movement of the empty can 1 can be suppressed.

According to the above-mentioned inspection position, it is possible to judge whether the flanges of empty cans are good or bad automatically and at high speed (for example, about 30 cans per second). Since the current speed of the can production line is about 10 cans per second, the functionality of the above inspection equipment is sufficient for practical use.
By introducing this to the canning production line,
It is expected that the quality and yield of canned goods will improve.

FIG. 9 shows an example of a light shielding member 29 suitable for the case where the empty cans 1 are supplied in a state in which they are in contact with each other.
This light shielding member 29 is a plate-shaped member that is integrally formed on the diameter of the empty can 1 inside the light shielding plate 13 similar to that described above in the moving direction. If such a light shielding member 29 is used, the light emitted from the illumination device 11 will be diffusely reflected at the opposite boundary portion 1c and directly enter the television camera 12, and will also be diffusely reflected at the flange 1a of the empty can 1 adjacent to the front and back. This prevents the camera from directly entering the television camera 12. In this case, flange 1 of empty can 1
Uninspected areas that are not illuminated by light occur at the front and rear of the moving direction of a, but this can be solved, for example, as follows. In other words, the empty cans 1 on the conveyor 10
Two sets of similar inspection devices are placed on the movement path of 1
After inspecting with the inspection device of the third stage, the empty can 1 is rotated by a predetermined angle around a vertical axis by a known appropriate method.
The second-stage inspection device inspects the portion including the uninspected area. When a defective product detection signal c is output from both or one of the inspection devices, the product is determined to be defective.

In the above embodiment, the empty cans 1 and the conveyor 10 are used to move the empty cans, but the empty cans 1 and the conveyor 10 are used to move the empty cans, but the empty cans 1 and the conveyor 10 can be moved by other means such as a rotary table.

Effects of the Invention According to the empty can inspection device of the present invention, as described above, the television camera images the flange of the empty can through the inside of the ring-shaped lighting device,
The lighting system and TV camera are arranged so that the light reflected by a normal flange does not directly enter the TV camera, so one TV camera can image the flange of an empty can once, and the shape of the flange can be determined. The quality of the product can be easily and accurately inspected.
Therefore, there is no need to take images many times by changing the vertical relative distance between the empty can and the illumination device, and accurate inspection can be performed in a short time. Therefore, defective products can be removed before empty cans are supplied to a can manufacturing line, etc., and product quality and yield can be improved.

In addition, the television camera has a shutter function synchronized with the vertical synchronization signal in the composite video signal representing the television image, and the lighting device is equipped with a light source that is turned on at a power frequency synchronized with the vertical synchronization signal. This reduces blurring of the TV image caused by the movement of the can, making inspections more accurate.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of an empty can inspection position showing an embodiment of the present invention, Fig. 2 is a perspective view showing an enlarged portion of the light shielding plate and light shielding member in Fig. 1, and Fig. 3 is the object to be inspected. FIG. 4 is a cross-sectional view showing an enlarged view of the flange portion of an empty can, FIG.
FIG. 6 is a block diagram showing an example of the electrical configuration of the processing device; FIG. 7 is a diagram showing an example of the electrical configuration of the power supply section of the lighting device. Block diagram, Figure 8 is a time chart showing signals of each part of the processing device and power supply section, Figure 9 is
The figure is a drawing corresponding to FIG. 2 showing a modified example of the light shielding member. 1... Empty can, 1a... Flange, 1b... Body part, 1
c... Boundary portion, 10... Conveyor, 11... Lighting device, 12... Television camera, 15, 29... Light shielding member, 16... Processing device, 17... Can detector, 19... Power supply section.

Claims (1)

[Scope of Claims] 1. A device for inspecting the shape of a flange at an open end of an empty can, comprising means for sequentially moving a plurality of empty cans with their open ends facing up; A ring-shaped lighting device is arranged horizontally above the moving path, a television camera is arranged downward above the lighting device and images the flange of the empty can through the inside of the lighting device, and the flange is imaged based on the TV image of the flange. The lighting device and the television camera are arranged so that the light reflected by the normal flange does not directly enter the television camera. The lighting device has a shutter function synchronized with a vertical synchronization signal in the video signal, the lighting device is equipped with a light source that is turned on at a power frequency synchronized with the vertical synchronization signal, and the processing device is configured to perform An empty can inspection device that determines that the shape of the flange is defective when a bright area appears. 2. Inspection of empty cans according to claim 1, wherein the processing device detects the occurrence of a particularly bright part in a television image by checking the signal level of a composite video signal representing the television image. Device. 3. The empty can inspection device according to claim 2, wherein the processing device examines the signal level only of the composite video signal for one field of a television screen immediately after the empty can arrives directly below the lighting device. . 4. The empty can according to any one of claims 1 to 3, wherein the lighting device includes a light shielding member that prevents light from reaching the boundary between the flange and the body portion on the opposite side of the empty can. Can inspection equipment.