JPS61199875A - Metal ball detector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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.

[1 Summary of the Invention] The metal ball detection device according to the present invention has one pole of a magnet brought into contact with the wall of the path through which the metal sphere passes, and the angle formed with the magnet is between 45° and 135° with the center of the path as the apex. A magnetic sensor is provided within the range, and the passage of the metal sphere is detected based on the magnetic sensor output, and an abnormal signal is output 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 misidentifying 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. With conventional detection equipment! , a mechanical or optical detection method has been proposed, and a device has been proposed in which a magnetic rose 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 a patent application
No. 8-210573 proposes a metal ball detection device in which a magnetic sensor is placed in a position where there is a large change in magnetic flux without facing a magnet, and detects a metal ball passing through a conveyance route (unpublished work). ). .

However, according to such a metal ball detection device, the effect of an external magnetic field is reduced because it is a magnetically closed loop, but when an external magnetic field is applied due to an open magnetic path, the metal ball The drawback is that there is a possibility that a metal ball may be mistakenly detected even though no metal ball has passed through the sensor.

[Purpose of the invention]

The present invention solves the problems of such a metal ball detection device, and is capable of detecting a metal ball with high magnetic circuit efficiency, and even when an external magnetic field is applied, it can identify it as a metal ball and generate an abnormal signal. The object of the present invention is to provide a metal ball detection device capable of outputting.

[Structure and effects of the invention]

In the present invention, one pole of a magnet is brought into contact with the wall of the passage path of a metal sphere, and the angle formed with the magnet is from 45 degrees to 1 in a plane perpendicular to the passage path including the magnet, with the center of the passage path as the apex.
A magnetic sensor is arranged within a 35° range with the magnetic flux detection surface facing the apex, and 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. 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, the device identifies a pulse width obtained from the magnetic sensor and detects a predetermined pulse width. The present invention is characterized by having a pulse width identifying means for detecting a sensor output exceeding the width as an abnormal signal.

According to the present invention having such characteristics, it is possible to reliably detect a metal ball because the magnetic flux changes greatly depending on the presence or absence of a metal ball. If the magnetic sensor detects a long signal that significantly exceeds the time required for the metal ball to pass, it is possible to detect an abnormality as being caused by some kind of magnetic field being applied from the outside. 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.

[Explanation of Examples]

(Principle of the invention) Two media with different magnetic permeabilities (magnetic permeability μnl + μn2
), when the angle of incidence and the angle of refraction at the boundary surface of the medium are θnl and θn2, the following equation % is established between them, 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 90 degrees or more when passing through the metal ball. The present invention detects a metal ball using such magnetic flux properties and identifies an abnormal signal 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 substance, and its inner diameter is approximately equal to the length of each sphere so that each sphere can pass through it one by one. The passage path 1 may be an octagonal prism on the inner surface as shown in FIG. 2, or may be a proximal cylinder. A sensor section 2 is provided at a position where a metal ball passing through this passage l is to be detected. Sensor part 2
has a frame 3 made of a non-magnetic material such as epoxy resin and formed to surround the passage 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 this 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, a magnetic flux collecting plate 6 made of a magnetic material and concentrating magnetic flux is provided between the Hall element 5 and the passing path 1, and the center of the magnetic flux collecting plate 6 and the Hall element 5 and the center point of the passing path 1 are set as shown in FIG. Match them as shown in . 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 l. If the angle between the permanent magnet 4 and the ball element 5 is θ, then θ
For example, the angle is 90°. 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.

FIG. 3 shows the rate of change in magnetic flux calculated using the angle θ at which the magnet and Hall element are arranged as a parameter. 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 is present, the magnetic flux refracted by the metal ball 9 acts perpendicularly on the Hall element 5, but when the metal ball is not present, the Hall element The magnetic flux flowing in and out of the magnet 5 is bent by the fringing effect, so that it almost no longer 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 IO. Detection circuit 1
0 indicates a detection circuit that is connected to the Hall element 5 and detects the presence or absence of a metal ball, and may be constructed by providing an external circuit on the printed circuit board 8, as shown in FIG. By integrating the sensor into the same panocage, the effects of temperature drift and the like can be offset, and the detection circuit can be made stable against temperature changes without providing a temperature compensation circuit.

Now, in this figure, power input is given to the Hall element 5 via the stabilized power supply 11, and a constant current is supplied to the Hall element 5. Then, the output obtained from the Hall element 5 is amplified by the amplifier 12, and the Schmitt trigger circuit 1
The waveform is shaped by 3. Schmitt trigger circuit 13
The output is amplified by the output circuit 14 and given to the outside as an output. Figure 5 (a), (b), (cl,
fd) is a circuit diagram showing identification means for identifying the pulse width of the output of this detection circuit IO. In FIG. 5(a), the output of the output circuit 14 of the detection circuit 10 is applied to the outside through a terminal 15 as a metal ball detection signal, and is also connected to an integrating circuit consisting of a resistor R16 and a capacitor C17. One end of the capacitor C17 is connected to ground, and the integrated output is given to the outside as an abnormality detection signal from a terminal 18 connected to the resistor R16 and the capacitor C17.

(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 hits the sensor section 2, the magnetic flux density of the Hall element 5 gradually increases. Then, at time tl 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 density as shown in FIG. Magnetic flux passes through the Hall element 5.

Therefore, a voltage corresponding to the magnetic flux density is obtained as shown in FIG. 6(b). If this signal is amplified by the amplifier circuit 12 of the detection circuit 10, waveform-shaped by the Schmitt trigger circuit 13, and amplified by the output circuit 14, the sixth
A square wave output as shown in Figure (C) 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 20m5, then the time constant of the integrating circuit Select a value that is sufficiently larger than that. In this case, as shown in FIG. 6 (dl), almost no signal can be obtained from the terminal 18.

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 L2 as shown in FIG. 6 (al). In this case, a square wave output is similarly obtained from the detection circuit 10 as shown in FIG. 6(a).

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. 6 (dl).

Therefore, when this signal reaches a saturation level, the abnormal signal can be identified as being caused by an external magnetic field, and the detection of the metal ball can be stopped.

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. 5(b), a signal close to a square wave can be obtained. I can do it. Furthermore, if the output of the integrating circuit is fed to the comparator 20 as shown in FIG. 5 [C], it becomes possible to reliably detect abnormal signals. Furthermore, as shown in FIG.
1, and by identifying signals with a predetermined width or more, it is also possible to distinguish between a signal due to regular metal ball detection and a signal based on an external magnetic field.

[Brief explanation of drawings]

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 the rate of change, FIG. 4 is a circuit diagram showing one embodiment of the detection circuit 10, FIG. 5(a), FIG. 5(b), FIG.
C) and FIG. 5(d) are circuit diagrams showing the electrical configuration of the metal ball detection device including the detection circuit 10, respectively, and FIG. 6 is a waveform diagram showing waveforms of each part. 1-----・- Passing route 2-----------Sensor part
4.-11---Permanent magnet 5--Hall element 6--Magnetic collector plate 7-----One magnetic path 10---
---1 detection circuit 12・--1--=amplifier 13
−−−−−−−Schmitt trigger circuit 14−−−−
-One output circuit 15, 18-・One terminal 19-
-, Transistor 20... Comparator 2t - - 1 - - Pulse time measurement circuit Patent applicant Tateishi Electric Co., Ltd. Patent attorney Yoshiki Okamoto (and 1 other person) Fig. 1 1-- --- A-tonni-ro 4------Ichieki Ki-seki 5-------Hallmi k pre-6---------Suemoto Sou 7------Line route Fig. 2 Fig. 3 Figure 4 Figure 6 Figure 5 (a) 1''''-11111111''''''''-1 Figure 5 (b
) Figure 5(d)

Claims (6)

[Claims] (1) One pole of a magnet is brought into contact with the wall of the passageway of the metal sphere, and the angle formed with the magnet is 45° with the center of the passageway as the apex in a plane perpendicular to the passageway including the magnet.
a magnetic sensor with a magnetic flux detection surface facing the apex within a range of 135° from , 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 sphere based on the output of the magnetic sensor, wherein the pulse obtained from the magnetic sensor A metal ball detection device comprising pulse width identification means for identifying a width and detecting a sensor output exceeding a predetermined width as an abnormal signal. (2) The metal ball detection device according to claim 1, wherein the magnet is a permanent magnet. (3) The metal ball detection device according to claim 1, wherein the magnetic sensor is a Hall element. (4) 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. (5) The metal ball detection device according to claim 1, wherein the angle formed by the magnet and the magnetic sensor is approximately 90° with the center of the passage path as the apex. (6) 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.