JPH0563194B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a detection device for detecting a metal sphere passing through a predetermined path.

[Summary of the invention]

The metal ball detection device according to the present invention is provided with a magnetic sensor in which one pole of a magnet is brought into contact with the wall of the path through which the metal sphere passes, the center of the path is set as the apex, and the magnetic flux detection surface is directed toward the apex, and the magnetic sensor output is based on the magnetic sensor output. The magnetic sensor detects the passage of a metal sphere and outputs an abnormal signal when the output obtained from the magnetic sensor exceeds a predetermined time. In this way, the metal sphere can be detected reliably, and the possibility of erroneously recognizing the passage of the metal sphere due to magnetic field changes other than the passage of the metal sphere due to the application of a magnetic field from the outside can be reduced.

[Background of the invention]

Conventionally, various detection devices have been proposed for detecting the number of metal spheres passing through a conveyance path for pachinko balls, coins, and the like. Mechanical or optical detection methods have been proposed as conventional detection devices.
Furthermore, a device has been proposed in which a magnetic closed loop is formed and a magnetic sensor is provided in the loop to detect the passage of a metal ball. The applicant has already filed patent application No. 58-210573.
In this issue, we proposed a metal ball detection device that can detect metal spheres passing through a conveyance path by placing a magnetic sensor in a position where the magnetic flux changes are large without facing the magnet (unpublished).

However, according to such a metal ball detection device,
Because it is a magnetically closed loop, the influence of external magnetic fields is reduced, but if an external magnetic field is applied from the open side of the magnetic path, the metal ball may accidentally strike the metal even though it has not passed through it. The drawback was that there was a possibility that the ball could be detected.

[Purpose of the invention]

The present invention solves the problems of such a metal ball detection device, and it detects metal balls with high magnetic circuit efficiency, and even when an external magnetic field is applied, it identifies them as metal balls and outputs an abnormal signal. The object of the present invention is to provide a metal ball detection device that can detect metal balls.

[Structure and effects of the invention]

The present invention is a magnetic field in which one pole of a magnet is brought into contact with the wall of a passage path of a metal sphere, and a magnetic flux sensing surface is directed toward the apex with the center of the passage path as the apex in a plane perpendicular to the passage path including the magnet. arranging the sensor and providing a magnetic path made of a magnetic material that surrounds the other pole of the magnet and the magnetic sensor from the outside of the passage path;
A metal ball detection device that closes a magnetic path including the metal ball based on the passage of the metal ball and detects the passage of the metal ball based on the output of a magnetic sensor, wherein the pulse width obtained from the magnetic sensor is a predetermined width. The present invention is characterized by having a pulse width identifying means that identifies the pulse width as abnormal when the pulse width is greater than or equal to the pulse width.

According to the present invention having such characteristics, a metal ball can be detected by changes in magnetic flux, but if a long signal that significantly exceeds the time required for the metal ball to pass is detected by the magnetic sensor, the external It is possible to detect an abnormality by assuming that some kind of magnetic field has been applied. Therefore, even if a magnet or the like is brought close to the detection area of the metal ball, this will not be detected and only the passage of the metal ball can be reliably detected.

Furthermore, if the angle between the magnet and the magnetic sensor is set as described in claim 5, the change in magnetic flux caused by the passage of the metal ball is large, so that the metal ball can be detected reliably.

[Explanation of Examples]

(Principle of the invention) Two media with different magnetic permeabilities (magnetic permeability μ _o1 , μ _o2 )
When a line of magnetic flux passes through, let the angle of incidence and angle of refraction at the boundary surface of the medium be θ _o1 and θ _o2 , and the following equation is established between them: tanθ _o1 /tanθ _o2 = μ _o1 / μ _o2 , and the line of magnetic flux is refracted. According to the law of refraction, the magnet and magnetic sensor are placed at a predetermined angle across the passage of the metal ball, and the other pole of the magnet is surrounded by ferromagnetic material from the outside of the magnetic sensor and the passage. In this case, the magnetic flux is refracted by more than 90° when passing through the metal ball. The present invention detects a metal ball using the properties of magnetic flux, and
An abnormal signal is identified based on the time of the output signal.

(Configuration of Embodiment) FIG. 1 is a sectional view showing an embodiment of a sensor portion of a metal ball detection device according to the present invention. In this figure, the path 1 for the metal spheres to pass through is made of a non-magnetic material, and its inner diameter is approximately equal to the width of one sphere so that each sphere can pass through it one by one. The passageway 1 may be an octagonal prism on the inner surface as shown in FIG. 2, or may be a cylinder. A sensor section 2 is provided at a position where a metal ball passing through this passage path 1 is to be detected. The sensor section 2 has a frame 3 made of a non-magnetic material such as epoxy resin and formed to surround the passage path 1, and a shield plate for noise removal is provided within the frame 3. In this frame, a permanent magnet 4 is provided on one side of the passage path 1 so that one pole, for example, the N pole, is in contact with the passage path 1. A Hall element 5 is provided at a position of 90° with the center point of the passage as the apex. As is well known, the Hall element 5 is an element that generates a Hall electromotive force in a direction perpendicular to both of them when a current is passed in a certain direction and a magnetic field is applied perpendicular to the current direction. The induced voltage is proportional to the product of the current flowing through the Hall element and the magnetic flux density. Here, Hall element 5
A magnetic flux collecting plate 6 made of a magnetic material and concentrating magnetic flux is provided between the magnetic flux collecting plate 6 and the Hall element 5.
The center of the path 1 and the center of the passing route 1 are made to coincide with each other as shown in FIG. An L-shaped magnetic path 7 made of a ferromagnetic material is provided between the other S pole of the permanent magnet 4 and the Hall element 5, as shown in FIG.

FIG. 2 is an enlarged perspective view of the magnetic circuit portion. As shown in these figures, the magnetic path 7 constitutes a magnetic circuit that connects the permanent magnet 4 and the magnetic sensor 4, and has a right-angled bent portion as shown in the figure, and is connected to the center point of the passage path 1. If the angle between the permanent magnet 4 and the Hall element 5 is θ, then θ is, for example, 90°.
Arrange it so that Further, the sensor section 2 is provided with a detection circuit section for detecting the presence or absence of a metal ball on the printed circuit board 8, as shown in the figure.

Figure 3 shows the angle θ at which the magnet and Hall element are arranged.
This shows the rate of change in magnetic flux calculated using . As can be seen from this figure, the rate of change α between when a metal ball is passing and when it is not present is maximum when θ is 90°, and when θ is in the range of 45° to 135°, conventional metal ball detection This is larger than the rate of change in magnetic flux density due to the device.

In addition to this, the Hall element generates a Hall electromotive force only for the magnetic flux that acts perpendicularly to the current flowing through the Hall element. By the way, as shown in FIG. 1, in the case of the present invention, when the metal ball 9 exists, the magnetic flux refracted by the metal ball 9 acts perpendicularly on the Hall element 5, but when the metal ball does not exist, the magnetic flux acts perpendicularly to the Hall element 5. The magnetic flux flowing in and out of the Hall element 5 is bent by the fringing effect, so that it hardly acts in the vertical direction, which is the magnetic sensing direction of the Hall element. Therefore, in the case of the present invention, if a Hall element is used as a magnetic sensor, it is possible to further improve the amount of change in output compared to a normal magnetic sensor.

FIG. 4 is a circuit diagram showing the detection circuit 10. The detection circuit 10 is connected to the Hall element 5 and detects the presence or absence of a metal ball, and may be configured by providing an external circuit on the printed circuit board 8, as shown in FIG. If it is integrated in the same package as the element 5, the effects of temperature drift and the like can be offset, and a detection circuit that is stable against temperature changes can be obtained without providing a temperature compensation circuit.

Now, in this diagram, the power input is the stabilized power supply 11
is applied to the Hall element 5 via the Hall element 5.
A constant current is supplied to the The output obtained from the Hall element 5 is amplified by an amplifier 12 and waveform-shaped by a Schmitt trigger circuit 13. The output of the Schmitt trigger circuit 13 is amplified by an output circuit 14 and given to the outside as an output. 5a, b, c, and d are circuit diagrams showing identification means for identifying the pulse width of the output of the detection circuit 10. FIG. In FIG. 5a, the output of the output circuit 14 of the detection circuit 10 is output to the terminal 15 as a metal ball detection signal.
It is applied externally and is connected to an integrating circuit consisting of a resistor R16 and a capacitor C17. One end of capacitor C17 is connected to ground, and terminal 18 is connected to resistor R16 and capacitor C17.
The integrated output is given to the outside as an abnormality detection signal.

(Operation of this embodiment) Next, the operation of this metal ball detection device will be explained with reference to waveform diagrams. When the metal ball 9 passing through the passage path 1 is inserted into the sensor section 2, the magnetic flux density of the Hall element 5 gradually increases. Then, at time t1 when the metal ball 9 reaches a position where it almost penetrates the permanent magnet 4 and the Hall element 5, the magnetic flux density penetrating the Hall element reaches a maximum value, and thereafter decreases, so that the magnetic flux density in FIG.
A magnetic flux having a density as shown in FIG. 1 passes through the Hall element 5. Therefore, a voltage corresponding to the magnetic flux density is obtained as shown in FIG. 6b. This signal is detected by the detection circuit 1
0 amplification circuit 12, waveform shaping is performed by a Schmitt trigger circuit 13, and output circuit 14.
If amplified by , a square wave output as shown in FIG. 6c will be obtained. The time it takes for the metal ball to pass through path 1 is a minute time determined by the system in which the metal ball detection device is installed, but if the time T1 is, for example, about several mS to 20 mS, the time constant of the integrating circuit Select a value that is sufficiently larger than that. In this case, almost no signal is obtained from the terminal 18, as shown in FIG. 6d.

However, for example, when a magnet is artificially brought close to the sensor section 2 instead of passing through a metal ball, an external magnetic field is applied to the sensor section, and the magnetic flux density of the Hall element 5 increases at time t2, as shown in FIG. 6a. In this case, a square wave output is similarly obtained from the detection circuit 10 as shown in FIG. 6a. However, in this case, since the magnetic flux density increases during a time T2 which is much longer than the minute time T1 during which the metal ball normally passes, the output voltage of the integrating circuit increases as shown in FIG. 6d. Therefore, when this signal reaches a saturation level, it is possible to identify the abnormal signal as being caused by an external magnetic field or to stop detecting the metal ball.

In this embodiment, an integrator circuit is connected to the output terminal of the detection circuit 10, but if the output of the integrator circuit is discriminated by a transistor 19 as shown in FIG. 5b, a signal close to a square wave can be obtained. I can do it. Also the fifth
If the output of the integrating circuit is applied to the comparator 20 as shown in FIG. c, it becomes possible to reliably detect an abnormal signal. Furthermore, as shown in FIG. 5d, the output of the detection circuit 10 is fed to the pulse time measurement circuit 21, and by identifying signals with a predetermined width or more, it is possible to differentiate between the signal due to regular metal ball detection and the signal based on the external magnetic field. It is also possible to configure it so that it can be identified.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a metal ball detection device according to the present invention, FIG. 2 is a perspective view thereof, and FIG. 3 is a diagram showing magnetic flux when the angle θ at which the magnet and Hall element are arranged is used as a parameter. Graph showing rate of change, 4th
FIG. 5 is a circuit diagram showing one embodiment of the detection circuit 10.
Figure a, Figure 5b, Figure 5c, and Figure 5d are circuit diagrams showing the electrical configuration of the metal ball detection device including the detection circuit 10, respectively, and Figure 6 is a waveform diagram showing the waveforms of each part. . DESCRIPTION OF SYMBOLS 1... Passing route, 2... Sensor section, 4... Permanent magnet, 5... Hall element, 6... Magnetic collector plate, 7...
Magnetic path, 10...Detection circuit, 12...Amplifier, 13
...Schmitt trigger circuit, 14...Output circuit,
15, 18...Terminal, 19...Transistor, 2
0...Comparator, 21...Pulse time measurement circuit.

Claims (1)

[Scope of Claims] 1. One pole of a magnet is brought into contact with the wall of the passage path of the metal sphere, and the magnetic flux sensing surface is placed in a plane perpendicular to the passage path including the magnet, with the center of the passage route as the apex. Along with placing a magnetic sensor facing the top,
A magnetic path made of a magnetic material is provided that surrounds the other pole of the magnet and the magnetic sensor from the outside of the passage path, and the magnetic path including the metal ball is closed based on the passage of the metal ball, A metal ball detection device that detects passage of a metal sphere based on a magnetic sensor output, characterized by having a pulse width identification means that identifies an abnormality when a pulse width obtained from the magnetic sensor is equal to or greater than a predetermined width. Metal ball detection device. 2. The metal ball detection device according to claim 1, wherein the pulse width identifying means stops detecting the metal ball when an abnormality is identified. 3. The metal ball detection device according to claim 1, wherein the magnet is a permanent magnet. 4. The metal ball detection device according to claim 1, wherein the magnetic sensor is a Hall element. 5. The metal ball detection device according to claim 1, wherein the magnetic sensor is a magnetic sensor provided with a magnetic flux collecting plate made of a magnetic material on the detection surface side. 6. The metal ball detection device according to claim 1, wherein the angle formed by the magnet and the magnetic sensor is at a position of 45° to 135° with the center of the passage path as the apex. 7. The metal ball detection device according to claim 1, wherein the pulse width identifying means is an integrating circuit having a time constant larger than the transit time of the metal ball.