JPH0320792Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a metal object detection device used for detecting metal objects, such as pachinko balls in game machines.

Background technology and its problems Recently, devices for detecting metal objects, such as pachinko balls, have been developed to have higher detection accuracy than those using microswitches, so when a pachinko ball passes through an air-core coil, the oscillation circuit stops oscillating. A device has been proposed that detects the

FIG. 1 shows the electrical connection of such a proposed example. In the figure, oscillation transistors 1 and 2 are provided, the base of transistor 1 and the emitter of transistor 2 are connected to each other, and transistor 1 is connected to the emitter of transistor 2.
The collector of is connected to one end of a parallel resonant circuit 4 consisting of a pachinko ball detection coil 4a and capacitors 4b and 4c through a connecting terminal 3, and the other end of this resonant circuit 4 is connected to a transistor 2 through a connecting terminal 5.
Connect to the base of Here, the pachinko ball detection coil 4a is an air-core coil wound around the outside of the movement path 4d of the pachinko balls as shown in FIG. Place it so that it passes inside the. Further, the emitters of the transistors 1 and 2 are respectively grounded through a transistor 6 as a current source, a resistor 7, a transistor 8, a resistor 9, and a connection terminal 10. Note that the collector of the transistor 2 is connected to the connection terminal 11 to which the positive power supply terminal +Vcc is connected. Further, the emitter of the transistor 1 is connected to the connection point of the capacitors 4b and 4c of the resonant circuit 4 via the connection terminal 12 and the feedback resistor 13 for sensitivity adjustment. Note that the resonant frequency of resonant circuit 4 _{is 0.}
is given by the following equation, where L ₁ is the inductance of the coil 4a, and C ₁ and C ₂ are the capacitances of the capacitors 4b and 4c, respectively.

Also, the transistor 14 as a bias circuit,
15 and 16 are provided, and the collector of the transistor 14 is connected to the base of the transistor 15 and connected to the connection terminal 18 via a resistor 17. The connection terminal 18 is connected to an external power supply via this circuit and the connection terminal 18 when the power supply voltage becomes low, and controls the amount of current of the current source in the circuit. Therefore, the power supply voltage is within a predetermined range, for example 4 to 14V.
It can be used over a wide range of degrees. Further, the collector of the transistor 14 is connected to the connection terminal 31 via the resistors 19 and 20, and the collector of the transistor 14 is
The connection point of is connected to the base of transistor 16. Furthermore, the emitter of transistor 14 is connected to resistor 2.
1 to the connecting terminal 10, the collector of the transistor 15 is connected to the connecting terminal 11, and the emitter of the transistor 15 is connected to the connecting terminal 10 through a resistor 22. Further, the collector of the transistor 16 is connected to the connection terminal 11, the emitter is connected to the base of the transistor 2, and the transistor 16 is connected to the connection terminal 10 via the resistor 23. Further, the base of the transistor 14 is connected to the emitter of the transistor 15 and also commonly connected to the bases of the transistors 8 and 6. The resistors 19, 20, 21 and transistors 14, 15 set the current amount of the current source, and the transistor 16 sets the bias voltage that provides a secondary power source for the oscillation circuit.

Also, a pair of transistors 24 as detection means
and 25, the base of transistor 24 is connected to the collector side of transistor 1, and the base of transistor 25 is connected to the base side of transistor 2. Further, the emitters of the transistors 24 and 25 are connected in common, and then connected to the connection terminal 10 via a transistor 26 as a current source and a resistor 27, and the base of the transistor 26 is commonly connected to the bases of the transistors 6, 8, and 14. . In addition, the common connection point of each emitter of the transistors 24 and 25 is connected to a large capacity capacitor 2 through a connection terminal 28.
9, and the other end of this capacitor 29 is grounded.

Furthermore, the collector of transistor 24 is connected to terminal 1.
1, the collector of transistor 25 is connected to connection terminal 11 via the collector-emitter path of transistor 30 and resistor 31, and the collector and base of transistor 30 are interconnected and then connected to the base of transistor 32. The emitter of the transistor 32 is connected to the connection terminal 11 through a resistor 33, and the collector is connected to the connection terminal 10 through a resistor 34 and a diode 35.
In other words, transistors 30 and 32 constitute a so-called current mirror circuit.

Further, the collector of the transistor 32 is connected to the base of the transistor 36, and the collector of the transistor 36 is connected to the base of the transistor 36.
Its collector is connected to the connection terminal 11 via the resistor 37, and its emitter is connected to the connection terminal 10. Further, the collector of the transistor 36 is connected to the base of the transistor 38, and the collector of the transistor 36 is connected to the base of the transistor 38.
The collector of 8 is connected to a connection terminal 39 serving as an output terminal, and the emitter is connected to a connection terminal 10. Transistors 36 and 38 constitute a switching circuit. Note that the parts surrounded by the connection terminals 3, 5, 10, 11, 12, 18, and 28 can be converted into ICs, so if they are converted into ICs, these connection terminals can be used as external connection terminals. In this case, the parallel resonant circuit 4 and the capacitor 29 are externally attached.

Next, the circuit operation will be explained. When the pachinko ball 4e moves within the mover 4d and passes through the coil 4a, the Q of the resonant circuit 4 becomes low and its impedance (2πf ₀ L ₁ Q) also becomes small. Therefore,
The amount of positive feedback from the resonant circuit 4 to the emitter side of the transistor 1 is not sufficient, and the circuit does not oscillate. When this oscillation circuit is not oscillating, the base potentials of transistors 24 and 25 are the same, so the current flowing through transistor 26 as a current source is 1/2 that of transistor 26.
It flows as a collector current of 4.25. Further, since the transistors 30 and 32 constitute a current mirror circuit, a collector current equal to the collector current of the transistor 25 flows to the collector side of the transistor 32. Therefore, the transistor 36
is turned on, thereby turning off the transistor 38, and therefore an output of "1" is obtained at the connection terminal 39 serving as an output terminal.

On the other hand, when the pachinko balls are away from the coil 4a, the Q of the resonant circuit 4 increases, and its impedance also increases. Therefore, since sufficient positive feedback is applied from the resonant circuit 4 to the emitter side of the transistor 1, this circuit oscillates as a Colpitts oscillation circuit. The maximum amplitude voltage of oscillation at this time is approximately
4V _BEP-P (twice the sum of the base-emitter voltage of transistors 1 and 2).

When the oscillation circuit is oscillating, a voltage of about 4V _BEP-P is applied to the base of the transistor 24, as shown by curve a in FIG. 2, centered around the secondary power supply Vcc'. At this time, a large capacity capacitor 29 is connected to the emitter of the transistor 24 via the connection terminal 28, so that the emitter side has Vcc'+2V _BE (transistors 1, 2) as shown by curve b in FIG. base-emitter voltage)
A DC voltage of V _BE ′ (base-emitter voltage of transistor 24)≒Vcc′+V _BE is obtained. In other words, the oscillation output is peak-detected. As a result, the base-emitter of the transistor 25 is reverse biased, and the transistor 25 is turned off. This results in transistors 30 and 32
The collector current of becomes zero, and the transistor 36 is turned off. When the transistor 36 is turned off, the transistor 38 is turned on, and the connection terminal 39 is turned on.
An output of "0" is obtained.

Therefore, the output of the connection terminal 39 is a binary logic of "0" and "1" corresponding to the on/off state of the transistor 38. Note that by appropriately selecting the constant current amount of the transistor 26 and the value of the capacitor 29, the oscillation sensitivity can be adjusted to hysteresis characteristics, that is, the time when a conductive object approaches the detection coil and oscillation stops, and vice versa. It is also possible to control the difference in time between when the conductive body separates from the coil and oscillation starts.

According to this proposed example, it is possible to mount everything from the detection coil to the detection section including the switching circuit on the same board, and it is possible to integrate the circuits other than the resonant circuit 4 and the capacitor 29 into ICs. Also, variations in oscillation sensitivity due to element variations and changes in coil sensitivity due to temperature are eliminated, and the reliability of the circuit can be improved. However, in this metal object detection device, the air core coil 4a is wound around a bobbin (not shown) as a resin insulating winding frame, and the size of the metal object detection device is increased by forming the bobbin separately. However, problems such as an increase in the number of parts and an increase in manufacturing costs became problems.

Purpose of the invention The present invention has been made in view of the above points, and an object thereof is to provide a small and inexpensive metal object detection device.

Summary of the invention The present invention is a metal object detection device that detects a metal object passing through an air-core coil. The air core coil is fixed to the body. According to the present invention, an inexpensive and compact metal object detection device can be obtained.

Embodiment Hereinafter, an embodiment of the metal object detection device of the present invention will be described with reference to FIGS. 4 and 5. In these FIGS. 4 and 5, corresponding parts to those in FIGS. 1, 2, and 3 are given the same reference numerals, and detailed explanation thereof will be omitted.

In FIG. 4, reference numeral 40 indicates a housing for a metal object detection device made of ABS resin, for example.
0 is provided with a ring-shaped groove 40a for inserting an air-core coil 4a' made of self-fused copper wire, and a hybrid IC board 41 with the air-core coil 4a' attached externally and configured with a predetermined electronic circuit. A groove 40b for insertion is provided. Here, this air core coil 4
A' is formed into a shape that fits into the ring-shaped groove 40a by wrapping a self-bonding copper wire around a bobbin (not shown) in advance and heating it. Moreover, this IC board is placed on the printed wiring board 41a.
The IC and chip parts are mounted and soldered. In addition, in Fig. 5, 42 is, for example, an ABS
A lid for a casing made of resin is shown, and this lid 42 is fixed to the casing by thermocompression bonding through protrusions 43, 44, 45, 46, and 47 formed at predetermined positions of the casing 40. do. Then, when the casing 40 and the casing 42 are fixed together by thermocompression bonding, the air-core coil 4a' is sandwiched between the casing 40 and the lid 42, and the axial direction of the air-core coil 4a' is defined and fixed. I'll do what I do. The other parts shall be constructed in the same manner as in the proposed example described above.

In this embodiment configured in this manner, when a pachinko ball passes through the air-core coil 4a', the oscillation of the oscillation circuit is stopped and the passage of the pachinko ball is detected by the metal object detection device.
The detection device used for this detection has a separately formed bobbin installed in the ring-shaped groove 40a, and there is no need to arrange the air core coil 4a' there, so the number of parts is reduced and the form is suitable for miniaturization. being done.

According to the present embodiment described above, the air-core coil 4a' is fixedly arranged in the metal object detection device together with the case body and the lid body, without forming a separate bobbin. The advantage is that a compact metal object detection device can be obtained.

Further, in the above example, an example was described in which a pachinko ball as a metal object is detected, but it can be similarly used to detect a screw or the like.

Effects of the invention According to the metal object detection device of the present invention, there is no need for a separately formed bobbin, and the air core coil is fixed together with the lid body and the casing body, so the number of parts of the metal object detection device can be reduced. There is an advantage in that a compact device can be completed with reduced manufacturing costs.

[Brief explanation of drawings]

1, 2 and 3 are diagrams for explaining the metal object detection device, and FIGS. 4 and 5 are exploded perspective views showing one embodiment of the metal object detection device of the present invention. 4a' is an air core coil, 40 is a housing, 40a and 4
0b is a groove, 41 is a hybrid IC board, 42 is a lid, and 43, 44, 45, 46 and 47 are protrusions.

Claims (1)

[Scope of utility model registration request] The air-core coil is placed in a case having an air-core coil insertion groove provided around a hole through which a metal object passes, together with a detection circuit board housed in a groove communicating with the air-core coil insertion groove, and In a metal object detection device that detects a metal object passing through the air-core coil by fixing the air-core coil to the air-core coil by fixing the air-core coil to the air-core coil, the air-core coil is once wound around a bobbin. 1. A metal object detection device, characterized in that it is formed of a self-fusing copper wire that is heated through a self-welding copper wire and is shaped to have a predetermined width in the direction in which the metal object passes.