JP7358907B2 - Coin appearance inspection device - Google Patents

Description

The present invention relates to an appearance inspection device that mainly inspects the appearance of coins, such as patterns formed on the front and back surfaces and edges, in the final process of a coin manufacturing line.

In the coin production line, defective products occur due to various reasons. Types of defects include, for example, chipped coins, misaligned or unclear patterns, eccentric holes, chipped coining/stamping, dirt on coins, and mixing of different types of coins.In the final process, a visual inspection is performed. It is required to reliably distinguish and sort the good coins without defects and the defective coins with defects.
The appearance inspection includes not only the patterns on the front and back sides of the coin, but also the finish of the irregularly shaped jagged pattern formed on the edge to prevent counterfeiting.

In the past, the mainstream was visual inspection, in which inspectors visually inspected the appearance of coins, but about 15 years ago, appearance inspection equipment was introduced that processes images captured by cameras to determine whether the appearance is good or bad. There is. Early visual inspection equipment had to expose the coin while it was stationary due to limitations in camera sensitivity, so an index table that held the coin was used to repeatedly accelerate, decelerate, and stop the coin. The coin is transported, and images of the front and back surfaces and edges of the coin are taken at the stop timing in the transport process.

Here, FIG. 9 is a configuration diagram showing the main parts of a conventional visual inspection apparatus (hereinafter referred to as the first conventional technique). Its specifications include testing coins circulating in Japan (500 yen, 100 yen, 50 yen, 10 yen, 5 yen, 1 yen), and has a processing capacity of 850 coins/minute. This visual inspection device is installed, for example, in the final process of a coin manufacturing line that continuously manufactures 500 yen coins in fixed lots.
The configuration and operation of this visual inspection device will be explained below.

In FIG. 9(a), uninspected coins C0 are put into the coin feeder 10, aligned in an upright position by the centrifugal force of the internal rotation mechanism, and sent to the conveyance guide 20 arranged in the vertical direction. The coins C0 in the conveyance guide 20 are distributed to the first and second conveyance guides 21 and 22 by the two-row sorter 30, and are continuously supplied to the cutting section 40 at a speed close to free fall. The cutout section 40 includes first and second stockers 41 and 42 that rotate in opposite directions, and a plurality of coins C0 in each of the conveyance guides 21 and 22 are placed in a continuous state at the entrances of these stockers. I'm waiting.

The first and second stockers 41 and 42 rotate in synchronization with the first and second index tables 51 and 52, which rotate in opposite directions, respectively, and the respective index tables 51 and 52 rotate at the timing when each index table 51 and 52 stops. Coin C0 is set in segments 53 and 54. Here, the segments 53 and 54 have a function of holding the coin C0 to be imaged, as will be described later.

For example, the outer diameter of a 500 yen coin is 26.5 [mm], and in order to inspect it at a processing capacity of 850 coins/minute, the above outer diameter of 26.5 [mm] must be inspected at 60 [s]/850. It is necessary to set the conveyance speed so that it moves (falls), but since the moving distance due to free fall is 24 [mm] (=9.8 [m] x 0.07 ² /2), two parallel configuration Stockers 41, 42 and index tables 51, 52 are installed.

In the first and second index tables 51 and 52, segments 53 and 54 are formed at 36° intervals in order to set each 10 coins C0, and there are 18° between each segment 53 and 54. A phase difference of .
The index tables 51 and 52 repeat acceleration, constant velocity, deceleration, and stop, for example, at a 36° cycle to carry the coin C0 to the first-side imaging position P1 and the second-side imaging position P2, and the timing at which each index table 51 and 52 stops is determined. Then, the first side camera 115 and the second side camera 125 (see FIG. 8(b)) take images of the first side and the second side (front side and back side) of the coin C0, respectively. The stop time of each index table 51, 52 during imaging is at least several [ms] in order to eliminate blurring of the captured image, and the exposure time for instantaneous illumination of each illumination unit 121, 122, 123, which will be described later, is 100 to 300 ms. It is set to [μs].

FIG. 9(b) shows the positional relationship between the first and second index tables 51, 52, the first-view camera 115, and the second-view camera 125, and corresponds to the side view of FIG. 9(a). .
As shown in FIG. 9B, the first-page camera 115 and the second-page camera 125 are arranged on both sides of the first and second index tables 51 and 52, respectively. The first side camera 115 captures one side (for example, the front side) of the coin C0 in the segments 53 and 54 when the segments 53 and 54 of the index tables 51 and 52 stop at the first side imaging position P1 in FIG. 9(a). The two-sided camera 125 images two sides (for example, the back side) of the coin C0 in the segments 53, 54 when the segments 53, 54 stop at the two-sided imaging position P2 in FIG. 9(a). .

Both the one-view camera 115 and the two-view camera 125 are housed in camera boxes 110 and 120. The configurations inside the camera boxes 110 and 120 are the same, and instantaneous illumination is applied to the coin C0 for 100 to 300 [μs] by oblique illumination units 111 and 121, scattering illumination units 112 and 122, and epi-illumination units 113 and 123. The reflected light from the front and back surfaces and edges of C0 is collected by lenses 114 and 124, and images are formed on the imaging elements of each camera 115 and 125. In order to ensure that the coin C0 remains stationary within the segments 53, 54, negative pressure air is applied from the back surface of each segment 53, 54 to suck the coin C0.
Although detailed description will be omitted, after determining whether the appearance of the coin C0 is good or bad based on images captured by the first side camera 115 and the second side camera 125, the good coin C is transferred to the transport path as shown in FIG. 9(a). The defective coins C1 and C2 are collected into the defective product collection boxes 61 and 62, while the defective coins C1 and C2 are collected into the defective product collection boxes 61 and 62 via the conveyor 80.

FIG. 10 is a functional block diagram of the main parts of the visual inspection apparatus shown in FIG. 9.
In FIG. 10, the index tables 51, 52 and camera boxes 110, 120 are shown as seen from above in FIG. 9(b). 116 and 126 are illumination power supplies; 135 is a coin arrival sensor that detects that the coin C0 has reached the first-side imaging position P1 and the second-side imaging position P2; The image processing device includes an input/output section) 134, and 140 is a PLC (programmable logic controller) for controlling the mechanism.

The image processing device 130 quantizes the coin to 80 [μm] per pixel, inspects the appearance quality by comparison processing with a reference image, etc., and outputs an inspection result signal to the PLC 140. Note that specific methods of image processing and appearance determination are not the gist of the present invention, and therefore will not be described here.
The PLC 140 sorts and discharges good coins and defective coins based on the inspection result signal from the image processing device 130 and timing signals such as the rotational position of each index table 51, 52 and the arrival position of the coin. generates and outputs various control signals and reject signals.

Next, FIG. 11 is an explanatory diagram of the driving principle of the index tables 51 and 52.
In FIG. 11, the continuous rotational motion of the servo motor M is converted by an indexing driver 55 via a timing belt 59 into a series of repetitive motions consisting of acceleration, constant velocity, deceleration, and stop, and is transmitted to an output shaft 56. This rotation of the output shaft 56 causes the first and second index tables 51 and 52 to rotate in opposite directions via bevel gears 57 and 58.
The capacity of the servo motor M is, for example, 5 [kW], and the index tables 51 and 52 with an outer diameter of about 400 [mm] are accelerated, constant-velocated, decelerated, and stopped seven times, and continuously rotated at 0.7 revolutions/second. It provides torque for stable operation.
Note that FIG. 12 is a timing chart showing the output of the servo motor M and the output of the indexing driver 55.

FIG. 13 is an explanatory diagram of the segments 53 and 54 of each index table 51 and 52 and the coin receiving parts 53a and 54a.
In consideration of variations in the attachment of the segments 53, 54 to the index tables 51, 52, core wobbling of the index tables 51, 52, etc., the coin receiving section is designed to stably transfer the coin C0 from the stockers 41, 42. In order to hold the coin in the coin receiving parts 53a and 54a, the inner diameter of the coin receiving parts 53a and 54a is set to about 1.3 times the diameter of the coin C0. As described above, since the inner diameters of the coin receiving parts 53a and 54a are larger than the diameter of the coin C0, the position and angle of the coin C0 in the coin receiving parts 53a and 54a are not stable but fluctuate.

Here, as a conventional technique for inspecting the appearance of a disc-shaped object such as a coin, an appearance inspection apparatus according to Patent Document 1 (hereinafter referred to as a second conventional technique) is known.
FIG. 14 is a configuration diagram of the main parts of the visual inspection device described in Patent Document 1. In FIG. 14, a ring-shaped mirror 150, a first ring-shaped LED 151, and a first camera 152 are sequentially arranged on the front side of the coin C0, and a transparent plate 153, a second ring-shaped LED 154, and a first ring-shaped LED 154 are arranged on the back side of the coin C0. Two cameras 155 are sequentially arranged. Further, 156 is an inclined conveyance surface on which the coin C0 moves due to its own weight, and 157 is a coin arrival sensor that detects that the coin C0 has reached the imaging position.
In this visual inspection device, the first camera 152 can image the front side of the coin C0, while the second camera 155 can image the back side and edge of the coin C0. It is possible to inspect the edge pattern at the same time.

Patent No. 5140510 (Figure 1, Figure 5, etc.)

In the first conventional technique shown in FIGS. 9 to 13, the processing capacity per unit time is low because the coin C0 is basically transported to the imaging position by movement by free falling motion. For this reason, the index tables 51, 52, stockers 53, 54, bevel gears 57, 58, etc. are arranged in two parallel configurations to increase processing capacity, but this increases the size of the entire device and makes the structure complicated. Ta.
In particular, the bevel gears 57 and 58 are expensive, and when the meshing portions of these bevel gears 57 and 58 wear out, variations occur in the positioning of the index tables 51 and 52. To avoid such inconveniences, it is essential to frequently adjust or replace the bevel gears 57, 58, resulting in a lot of effort and expense.
In addition, the segments 53 and 54 that hold the coin C0 are often made of resin to reduce weight, but when the coin C0 moves freely within the coin receiving parts 53a and 54a, the segments 53 and 54 that hold the coin C0 are As the circumferential surface wears and its inner diameter gradually increases, the stopping position of the coin C0 held by the coin receiving parts 53a and 54a becomes unstable. For this reason, the position of the coin C0 is out of the imaging range, and variations in the captured images become large, making it impossible to detect small defects in appearance.
In particular, if the center of the coin C0 deviates from the first side imaging position P1 or the second side imaging position P2, the edge of the coin C0 may or may not be visible, making it impossible to stably perform edge inspection. There was a problem.

In the visual inspection apparatus according to the second conventional technique shown in FIG. 14, the coin C0 moves by its own weight on the inclined conveyance surface 156 and reaches the imaging position. processing capacity is low.
Furthermore, this visual inspection device is designed to be mainly incorporated into a machine for determining authenticity of recovered coins or a coin depositing machine (paragraph [0014] of Patent Document 1, etc.), and is designed to be installed in the final process of a coin manufacturing line. It is not suitable for applications such as high-speed inspection of the appearance of coins.

Therefore, the problem to be solved by the present invention is to prevent the device from increasing in size and complexity by eliminating the need for the above-mentioned two-parallel configuration such as the index table and bevel gear, and to position the coin at a predetermined imaging position to capture the front and back surfaces and edges. It is an object of the present invention to provide a coin appearance inspection device that enables inspection of the quality of appearance by accurately capturing images and has improved processing capacity.

In order to solve the above problems, the invention according to claim 1 provides a coin feeder that accommodates a large number of uninspected coins, and a cutter that cuts out coins that are continuously supplied from the coin feeder by centrifugal force and gravity. an imaging unit that images the front and back surfaces and edges of the coin supplied from the cutting unit and reached the imaging position while the coin is moving; and judging whether the appearance of the coin is good or bad from the image taken by the imaging unit. a sorting section that sorts good coins and defective coins based on the results; and a conveyance guide that is arranged between the coin feeder, the cutting section, the imaging section, and the sorting section and guides the coins. The cutting section separates each of the plurality of coins supplied from the coin feeder side, maintains a certain gap between the coins, and applies a predetermined initial velocity and gravity to the coins, so as to separate the plurality of coins supplied from the coin feeder side and apply a predetermined initial velocity and gravity to the coins. The coins are cut out one by one in a direction, and the cutout section cuts out the coins supplied between the cutout disks by rotating a pair of cutout disks in opposite directions.

The invention according to claim 2 is the coin appearance inspection apparatus according to claim 1 , wherein the imaging unit includes a camera for one side and a camera for two sides, each of which images the first side and the second side of the coin that has reached the imaging position. further comprising a hollow conical prism that images the reflected light from the edge of the coin on the two-sided camera, and a slight delay time after the one side is imaged by the one-sided camera. The two sides are imaged almost simultaneously by the two-side camera, and the appearance of the coin is inspected based on images of the front and back sides and edges of the coin taken by the first-side camera and the two-side camera. It is something.

The invention according to claim 3 is the coin visual inspection apparatus according to claim 1 or 2 , in which the conveyance guide that reaches the imaging position is arranged in a substantially vertical direction.
Further, the invention according to claim 4 is the coin visual inspection apparatus according to claim 1 or 2 , in which the conveyance guide leading to the imaging position is arranged to be inclined at a predetermined angle with respect to the horizontal direction. be.

According to the present invention, the two-parallel configuration of the conveying means as in the first prior art is not required, thereby preventing the device from becoming larger and more complex, and the drive force transmission mechanism (gears, etc.) and segments of the index table being worn out. It is possible to accurately image the front and back surfaces of the coin, the patterns on the edges, and the surrounding angles by suppressing the misalignment of the coin caused by such factors.
Furthermore, compared to the first and second conventional techniques, the throughput of a series of steps including transportation, imaging, etc. can be improved.

1 is a configuration diagram of a visual inspection device according to a first embodiment of the present invention. FIG. 2 is a specific configuration diagram of a cutting section and its control device in FIG. 1; FIG. 2 is a configuration diagram of main parts of an imaging section in FIG. 1. FIG. FIG. 7 is an explanatory diagram of an opening in the vicinity of the coin imaging position of the conveyance guide. It is a timing chart showing a coin arrival detection signal, a first side exposure signal, and a second side exposure signal in the first embodiment. It is a block diagram of the external appearance inspection apparatus based on 2nd Embodiment of this invention. It is a block diagram of the external appearance inspection apparatus based on 3rd Embodiment of this invention. FIG. 3 is a diagram for explaining the relationship between the imaging position and the blur of the captured image. FIG. 1 is a configuration diagram showing the main parts of a visual inspection device as a first conventional technique. 10 is a functional block diagram of main parts of the visual inspection device shown in FIG. 9. FIG. 10 is an explanatory diagram of the driving principle of the index table in FIG. 9. FIG. 12 is a timing chart showing the output of the servo motor and the output of the indexing driver in FIG. 11. 10 is an explanatory diagram of the segment and coin receiving section in FIG. 9. FIG. It is a block diagram of the principal part of the visual inspection apparatus described in patent document 1 as a second prior art.

Embodiments of the present invention will be described below with reference to the drawings.
1(a) is a schematic overall configuration diagram of the visual inspection apparatus according to the first embodiment, FIG. 1(b) is a side view of the imaging section in FIG. 1(a), and FIG. 1(c) is a conveyance guide It is an explanatory view of the force acting on the uninspected coin inside.

In FIG. 1(a), uninspected coins (hereinafter also simply referred to as coins) C0 inputted from the previous process (coining process) of the coin production line are aligned in an upright state by the coin feeder 10 as in FIG. It is supplied to the cutting section 200 via a conveyance guide 20 arranged in the vertical direction.
The alignment output capability of the coin feeder 10 is set higher than the processing capability of the imaging section 250, which will be described later, and the supply amount is controlled so that a plurality of coins C0 are continuously retained at the entrance of the cutting section 200.
The coin feeder 10 supplies the coin C0 asynchronously with the cutting unit 200, and if the coin C0 is cut out before it reaches the entrance of the cutting unit 200, the coin C0 may be jammed and damaged. This will cause the equipment to stop. Therefore, a coin arrival sensor 301 is arranged upstream of the cutting section 200, and when the coin C0 is not detected by this sensor 301, the cutting operation is not performed.

The cutting unit 200 rotates a pair of cutting disks 210 and 220 in opposite directions to separate the coins C0 staying in the transport guide 20 one by one at predetermined time intervals while moving the coins C0 through the transport guide. Sends in 23 directions. In this embodiment, the coin C0 is not simply sent out (dropped) by gravity, but is sent out while giving a constant initial speed to the coin C0 by the rotational force of the cutting disks 210 and 220.
When the cutting unit 200 separates and sends out the coins C0 one by one, a gap is created between the coins C0 supplied to the imaging unit 250, so that the edges of the coins C0 are sufficiently illuminated with illumination light. Therefore, the reflected light from this edge is reliably incident on cameras 115 and 125 via lenses 114 and 124, which will be described later.

In the cutting unit 200, for example, if 500 yen coins are cut out every 60 [ms], one system can process 1000 coins/minute, and the index table etc. are configured in two parallel configurations as in the first prior art. The mechanism for transporting the coin C0 to the imaging position can be significantly simplified compared to the case where the coin C0 is transported to the imaging position. Since the throughput of a coining machine (not shown) installed upstream of this visual inspection device is approximately 850 sheets/min, the above-mentioned throughput is sufficient for the cutting section 200.
Note that at the entrance of the cutting section 200, it is desirable to shorten the vertical portion of the conveyance guide 20 so that the free falling speed of the coin C0 does not become too high.

FIG. 2 is a specific configuration diagram of the cutting section 200 and its control device.
As shown in FIG. 2(a), the cutting section 200 includes cutting disks 210 and 220 that rotate in opposite directions, and one coin C0 is placed between the outer peripheral surfaces of these cutting disks 210 and 220. A plurality of cutout protrusions 210a and 220a are formed at intervals. Note that P1 and P2 indicate imaging positions by an imaging unit 250, which will be described later.
If the type of coin C0 to be inspected is changed and the outer diameter of the coin is changed, the conveyance guides 20, 23 and cutting disks 210, 220 may be replaced.

FIGS. 2(b) and 2(c) show an example of the configuration of a control device for the cutting section 200. FIG.
FIG. 2(b) shows an example in which the cutting disks 210, 220 are rotated at high speed by synchronous servo motors 231, 232 with an output of 0.1 [kW], and FIG. 2(c) shows an example in which one synchronous servo motor This is an example in which the cutting disks 210 and 220 are rotated using the drive gear 233 and the drive gear 234. In these figures, 230 is a synchronous servo controller.
By rotating the cutting discs 210 and 220 synchronously at the same speed, the coin C0 can be cut out without rotating. The purpose of not rotating the coin C0 is to perform circumferential angle inspection (inspection of the shift angle (phase angle) of the coined pattern along the circumferential direction of the front and back sides of the coin C0) based on the patterns on the front and back sides when imaging the coin C0. is important.
Incidentally, as long as a slight rotation of the coin C0 is allowed, the coin C0 may be cut out using one cutting disk.

It is desirable that the coin C0 cut out by the cutting unit 200 be free from deviation in the x direction (horizontal direction) and floating in the z direction (direction toward the front of the page) in FIG. 1(a) described above. The conveyance surface of the conveyance guide 23 from the cutout section 200 to the imaging section 250 is designed to reduce the coefficient of friction, and especially to eliminate floating of the coin C0 in the z direction. It is effective to make it slightly tilted with respect to the y direction (the vertical direction, that is, the direction in which gravity acts) in (a).
FIGS. 1(b) and 1(c) show a state in which the conveyance direction 23a of the coin C0 in the conveyance guide 23, that is, the conveyance surface, is inclined by an angle θ with respect to the vertical direction. As a result, when the mass of the coin C0 is m and the gravitational acceleration is G, a pressing force F (=mG cos θ) shown in FIG. 1(c) is applied from the coin C0 to the conveyance surface, so that floating of the coin C0 can be suppressed. I can do it.

As described above, the cutting unit 200 cuts out the coin C0 in the direction of the imaging unit 250 while giving the coin C0 a total speed of the speed due to gravity and the initial speed. In the first conventional technique described above, the coin C0 is separated and transported by the segments of the index table, but in this embodiment, the complicated mechanism consisting of two parallel configurations such as the index table and segments is eliminated, and the coin C0 is separated and transported by the segment of the index table. A simple structure is adopted in which the coins C0 are conveyed one by one by disks 210 and 220.
As a result, unlike the first conventional technology, there is no risk of misalignment of the coin C0 at the imaging position due to wear on the inner circumferential surface of the coin receiving portion of the segment, and the coin C0 can be held at the imaging position with high accuracy. can be positioned.

Next, the configuration of the imaging section 250 in FIGS. 1(a) and 1(b) will be described.
The imaging section 250 includes oblique illumination sections 111 and 121, scattering illumination sections 112 and 122, epi-illumination sections 113 and 123, lenses 114 and 124, a camera for one surface 115, and a camera for two surfaces, as in FIG. 9B. 125, and camera boxes 110 and 120. The difference from FIG. 9B is that in this embodiment, the single-screen camera 115 and the dual-screen camera 125 are arranged on the same optical axis. Note that the configurations of an image processing device for processing images captured by the cameras 115 and 125, a PLC for mechanism control, a lighting power source, and the like are the same as those in FIG. 10.

Next, the configuration of the main parts of the imaging section 250 will be explained based on FIG. 3.
FIG. 3A shows, for example, the configuration of the camera box 120 side.
The two-sided camera 125 captures images of two sides of the coin C0, illuminates the edge of the coin C0 with a low-angle ring-shaped oblique light illumination unit 121, and directs the reflected light to a hollow conical shape with an opening in the center. The light is received by the prism 127. Then, as shown in FIG. 3(b), the reflected light from the edge CX of the coin C0 is reflected twice within the hollow conical prism 127 and guided toward the lens 124, and is directed to the image pickup element of the two-sided camera 125. form an image.
Thereby, the pattern G0 on the front or back surface of the coin C0 and the pattern GX on the edge CX can be imaged at the same time.

FIG. 4 is an explanatory diagram of the opening of the conveyance guide 23 near the imaging position of the coin C0.
In the first embodiment shown in FIG. 1, as shown in FIG. 4(b), openings 23B are provided on both the front and back sides of the conveyance guide 23. The length of the front and back sides of the opening 23B along the transport direction is L1=L2, and the first side camera 115 and the second side camera 125 capture images of the front and back sides and edges of the coin C0 almost simultaneously. Since the coin C0 is circular, the opening shape may be circular or oval.

Here, FIG. 5 shows a coin arrival detection signal at the imaging position, a first side exposure signal, and a second side exposure signal.
In FIG. 5, the coin arrival detection signal is obtained by the coin arrival sensor 303 of FIG. 1(a). Further, the exposure time T1 based on the first side exposure signal and the exposure time T2 based on the second side exposure signal are the exposure times by each illumination unit in the camera boxes 110 and 120 in FIG. 1(b), respectively. A slight delay time TD is provided between the exposure times T1 and T2 in order to prevent mutual interference between the illumination lights, but since the imaging unit 250 also inspects the rotation angle of the front and back surfaces of the coin C0, the delay time TD is maintained between the exposure times T1 and T2. By making the time TD very short, the first side and the second side are exposed and imaged almost simultaneously. Note that the time Tx in FIG. 5 is a time for adjusting the imaging position in order to take an image at the center of the camera according to the size of the coin C0.

Experience has shown that if an 80 [μm] corner area of the coin C0 is processed by one pixel, an inspection accuracy equivalent to that of a visual inspection by an inspector can be obtained. The exposure times T1 and T2 in this embodiment are about 20 to 40 [μs], and if the moving speed of the coin C0 is 1.0 [m/s], the movement of the coin C0 between 20 and 40 [μs] is Although this causes blurring of the captured image, it can be said to be at a negligible level compared to the above-mentioned 80 [μm] square.

The coin arrival detection signal in FIG. 5 is input from the coin arrival sensor 303 in FIG. 1(a) to the image capturing units 131 and 132 in FIG.
The coin arrival sensor 303 is installed at a position to detect that the coin with the smallest outer diameter has reached the imaging position, considering that it can handle multiple types of coins with different outer diameters, and the coin with the larger outer diameter Coins may be dealt with by switching the delay time corresponding to the travel time of the difference in outer diameter. For example, the outer diameter of a 5 yen coin is 22.2 [mm], and the outer diameter of a 500 yen coin is 26.5 [mm], and there is a difference of 4.3 [mm] between the two (the difference in radius is Approximately 2.2 [mm]). Therefore, assuming that the conveyance speed of the coin C0 at the imaging position is 1.0 [m/s], a delay time of approximately 2.2 [ms] may be set according to the above-mentioned difference in radius.

Next, FIG. 6 is a configuration diagram of a visual inspection apparatus according to a second embodiment of the present invention. In this second embodiment, a camera box 150 equipped with a peripheral angle camera 155 is arranged in place of the two-plane camera box 120 in the first embodiment of FIG. , a second cutout section 260 configured similarly to the cutout section 200 is added, and a camera box 120 equipped with a two-view camera 125 is arranged downstream of this cutout section 260. The configurations of the coin feeder 10, the cutting section 200, the sorting section 400, the defective product collection box 61, the good product collection box 90, etc. are almost the same as in FIG. 1(a).
In FIG. 6, the camera boxes 110, 120, 150 are drawn on the left and right sides of the conveyance guide 23 for convenience, but in reality, the camera boxes 110, 120 are on the front side and the back side in the direction perpendicular to the page (coin C0). The camera box 150 is located on the opposite side of the camera box 110 (on the same side as the camera box 120).
In FIG. 6, 303a, 303b, 304, and 305 are coin arrival sensors, 250a is an imaging section (camera box 110, 150), and 250b is an imaging section (camera box 120).

In this second embodiment, the front and back sides of the coin C0 are imaged by the first side camera 115 and the circumferential angle camera 155, and the opening of the conveyance guide 23 near the image pickup position is as shown in FIG. 4(c). become. That is, the length L1 of the opening 23C1 on the side of the camera 115 for one side is larger than the inner diameter L2 of the opening 23C2 on the side of the camera 155 for circumference, and the first side camera 115 can capture, for example, the entire surface of the coin C0 and The pattern at the edge is imaged, and the pattern at the center of the back side of the coin C0 is imaged by the peripheral angle camera 155. Regarding the exposure time during imaging in this case, a slight delay time is provided to prevent mutual interference between the illumination lights. Here, the inner diameter L2 of the opening 23C2 may be made slightly smaller than the outer diameter of the coin C0, and the shape of the opening 23C2 may be a circle or a vertically elongated oval.

By obtaining the captured image by the first side camera 115 and the captured image by the circumferential angle camera 155 as described above, the circumferential angles of the pattern on the front and back surfaces of the coin C0 can be detected.
In this embodiment as well, by inclining the conveying direction of the coin C0, that is, the conveying surface by an angle θ with respect to the vertical direction, a pressing force F (=mG cos θ) of the coin C0 against the conveying surface is generated, and the coin is pushed from the conveying surface. It is possible to suppress the floating of C0.
Similar to the cutting unit 200, the cutting unit 260 in FIG. 6 separates and cuts out coins C0 one by one while applying a predetermined initial speed to the coin C0. In order to make them the same, it is desirable that the initial velocities given to the coin C0 by the cutting units 200 and 260 be equal.

Although not shown, the camera box 150 for circumferential angle inspection in FIG. 6 may be removed and the camera boxes 110 and 120 may be left as they are. In this case, as shown in FIG. 4A, the opening 23A1 of the conveyance guide 23 is formed only on the side of the first side camera 115 at the imaging position P1 by the first side camera 115, and the second side camera 115 has an opening 23A1. 125, it is sufficient to form the opening 23A2 only on the two-view camera 125 side. Here, the lengths of the openings 23A1 and 23A2 are L1=L2.
By configuring as described above, the patterns on the front and back surfaces and the pattern on the edge of the coin C0 can be imaged at the imaging positions P1 and P2.

FIG. 7 is a configuration diagram of a visual inspection apparatus according to a third embodiment of the present invention.
In the first and second embodiments described above, the coin C0 is conveyed to the imaging position using a substantially vertical conveyance guide, but in this third embodiment, the coin C0 is conveyed to the imaging position using an inclined conveyance guide. This is an example.
In the first and second embodiments, the coin C0 after being cut out has a free falling motion due to the initial velocity + gravitational acceleration, and the longer the conveyance path becomes, the greater the conveyance speed of the coin C0 becomes. Since the exposure time by the illumination unit and the conveyance speed of the coin C0 affect the amount of blur in the captured image, the higher the conveyance speed, the greater the blur in the captured image. Therefore, in order to reduce blur, the position of the imaging section is limited, and this becomes a design and structural constraint.
In view of the above points, the third embodiment reduces the blur of the captured image and increases the degree of freedom in the arrangement of the imaging unit.

7(a) showing the third embodiment is an overall configuration diagram, (b) is a configuration diagram of an imaging unit, (c) is an AA sectional view, (d) is a BB sectional view, and (e) is an FIG. 3 is an explanatory diagram of the conveyance speed of the coin C0 in the conveyance guide 23 upstream of the imaging unit 250. FIG.
In FIG. 7A, the configurations of the coin feeder 10, cutting section 200, imaging section 250, sorting section 400, etc. are almost the same as in FIG. 1, but in this embodiment, the conveyance guides 20, 23, 24, etc. are inclined. The coin C0 is conveyed diagonally downward.
Similar to the first embodiment, the imaging unit 250 shown in FIG. 7B captures images of the patterns on the front and back sides and the pattern on the edge of the coin C0 almost simultaneously using the camera 115 for the first side and the camera 125 for the second side. do.
Further, as shown in FIG. 7C, on the conveyance guide 23, the conveyance direction of the coin C0 is inclined by an angle θ with respect to the vertical direction, similarly to the first embodiment. Furthermore, FIG. 7D shows an example of the sorting section 400, in which the conveyance guides 91 and 63 sort the coins C0 into good coins C and defective coins C1, and store them in the good coin collection box 90 and the defective coin collection box 61, respectively. to recover.

FIG. 7E is for explaining the conveyance speed V of the coin C0 in the conveyance guide 23. In this embodiment, the conveyance guide 23, that is, the conveyance surface of the coin C0 is moved downward by an angle Φ with respect to the horizontal plane. It is tilted. Therefore, the increase in the conveying speed due to the gravitational acceleration G can be reduced to G·cosΦ, and if the initial speed given to the coin C0 by the cutting unit 200 is _V0 , the conveying speed V of the coin C0 in the conveying guide 23 is , V=V ₀ +G·cosΦ.
As described above, by tilting the conveyance surface of the coin C0 downward by a predetermined angle Φ with respect to the horizontal plane, the conveyance speed of the coin C0 at the imaging position is reduced compared to the case where the coin C0 is conveyed in a substantially vertical direction. In addition to suppressing blur in the captured image, the entire device can be configured to be low in the vertical direction, contributing to miniaturization of the device.

Next, we will calculate the length of the transport path to keep the blurring of the captured image within the allowable range for the case where the coin C0 is transported almost vertically as shown in Figure 1 and the case where the coin C0 is transported at an angle as shown in Figure 7. Consider this based on FIG.
FIG. 8 is a diagram for explaining the relationship between the imaging position and the blur of the captured image.
In this embodiment, the appearance inspection is performed using a captured image in which the coin C0 is quantized to 80 [μm] per pixel. If the transport speed V of the coin C0 at the imaging position is 1.0 [m/s] and the exposure time is 20 [μs], the captured image will have a resolution of 20 [μm] (25% of the above resolution of 80 [μm]). ), but this level of blur is considered acceptable in practice.

If the processing capacity of the cutting unit 200 is 1000 coins/minute, the cutting unit 200 will cut out a coin C0 every 60 [ms]. Now, if the coin C0 is a 500 yen coin, its diameter is 26.5 [mm], so the initial velocity V ₀ of the cut coin C0 is V ₀ =26.5 [mm]/60 [ms]. ]=0.442 [m/s].
When the coin _C0 is conveyed in a substantially vertical direction as shown in FIG. m/s]) is t1=(V-V ₀ )/G=(1.0-0.442)/9.8=0.057 [s]. Therefore, the movement distance LX of the coin C0 from the cutting section 200 to the imaging position (see FIG. 8) is: LX=V ₀ · t1 + (1/2) G · t1 ² = 0.0252 + 0.0159 = 0.0411 [ m]=41 [mm].
On the other hand, when the coin C0 is transported on an inclined surface of Φ=45°, the gravitational acceleration G is apparently 1/2, so the coin C0 is transported at the transport speed V (=1.0 [m/s ]) is t2=(1.0-0.442)/4.9=0.114 [s]. Therefore, the moving distance LX of the coin C0 from the cutting section 200 to the imaging position is LX=0.0822 [m]=82 [mm].

In other words, if the coin C0 is to be conveyed in an almost vertical direction under the conditions of suppressing the blur of the captured image to about 20 [μm], the distance LX from the cutting section 200 to the imaging position must be set to 41 [mm]. However, when the coin C0 is conveyed on an inclined surface of Φ=45°, the above-mentioned distance LX becomes 82 [mm], and the arrangement of the imaging section 250 can be provided with a degree of freedom.
Note that since the inclination angle Φ of the inclined surface can be arbitrarily selected in addition to 45°, the imaging unit 250 can be placed at a desired position by a distance LX corresponding to this inclination angle Φ, and as a result, the image pickup unit 250 can be placed at a desired position. Fewer design or manufacturing constraints.

C0: Uninspected coin C1: Defective coin C: Good coin CX: Edges P1, P2: Imaging positions G0, GX: Pattern 10: Coin feeder 20, 23, 24, 63, 91: Conveying guide 23a: Conveying direction 23A1 , 23A2, 23B, 23C1, 23C2: Opening 61: Defective product collection box 90: Good product collection box 110, 120, 150: Camera box 111, 121: Oblique lighting section 112, 122: Scattered lighting section 113, 123: Epi-illumination Parts 114, 124: Lens 115: Camera for one surface 116, 126: Illumination power source 125: Camera for two surfaces 127: Hollow conical prism 130: Image processing device 140: PLC
155: Surrounding angle cameras 200, 260: Cutting parts 210, 220, 270, 280: Cutting out discs 210a, 220a: Cutting out protrusions 230: Synchronous servo controllers 231, 232, 233: Synchronous servo motor 234: Drive gear 250, 250a, 250b: Imaging section 301, 302, 303, 303a, 303b, 304, 305: Coin arrival sensor 400: Sorting section

Claims (4)

a coin feeder that accommodates a large number of uninspected coins;
a cutting unit that cuts out coins continuously supplied from the coin feeder by centrifugal force and gravity;
an imaging unit that images the front and back surfaces and edges of the coin supplied from the cutting unit and reached the imaging position while the coin is moving;
a sorting unit that sorts good coins and defective coins based on a result of determining whether the appearance of the coin is good or bad from the image taken by the imaging unit;
a conveyance guide that is arranged between the coin feeder, the cutting section, the imaging section, and the sorting section and guides the coins;
Equipped with
The cutting section separates the plurality of coins supplied from the coin feeder side, maintains a certain gap between the coins, and applies a predetermined initial velocity and gravity to the coins so as to move the coins toward the imaging section. It is cut out one by one,
A coin appearance inspection device, wherein the cutting section rotates a pair of cutting disks in opposite directions to cut out the coins supplied between the cutting disks. In the coin appearance inspection device according to claim 1 ,
The imaging unit includes a first-side camera and a second-side camera that respectively take images of the first side and the second side of the coin that has reached the imaging position,
further comprising a hollow conical prism that images the reflected light from the edge of the coin on the two-sided camera,
A coin whose two sides are imaged almost simultaneously by the two-side camera after a slight delay after the first side is imaged by the first-side camera, and which are imaged by the first-side camera and the second-side camera. A coin appearance inspection device characterized by inspecting the appearance of a coin based on images of the front and back sides and edges of the coin. In the coin appearance inspection device according to claim 1 or claim 2 ,
A coin appearance inspection device characterized in that the conveyance guide leading to the imaging position is arranged substantially vertically. In the coin appearance inspection device according to claim 1 or claim 2 ,
A coin visual inspection device, wherein the conveyance guide leading to the imaging position is arranged at a predetermined angle with respect to the horizontal direction.

Images