JPH0833765A - Metallic ball detection device - Google Patents

Abstract

PURPOSE:To individually separate and detect each metallic ball even when the metallic balls continuously pass through. CONSTITUTION:An oscillation circuit 2 is equipped with a LC resonance circuit 1 disposed close to the passing route of each metallic ball.. Current is fed to the oscillation circuit 2 through a constant current circuit 6, and an output circuit 3 is provided for the input side of the constant current circuit 6, where the output circuit increases/decreases passing current amperage in response to the change in the output level of the oscillation circuit 2. When each metallic ball comes close to the LC resonance circuit 1, the output level of the oscillation circuit 2 is lowered, and the passing current amperage is also decreased. Therefore, flowing current to connection terminals t, and t. is changed in response to the presence and absence of each metallic ball. Besides, the oscillation circuit 2 keeps oscillating regardless of the presence and absence of each metallic ball, the presence and absence of each metallic ball can thereby be judged with excellent repeatability based on the change in flowing current to the connection terminals t1 and t2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal ball detecting device for detecting the passage of a metal ball used in a game board or the like.

[0002]

2. Description of the Related Art Conventionally, FIG.
As shown in (1), an apparatus including an oscillating circuit 2 that includes an LC resonance circuit 1 and oscillates at a constant frequency, and an output circuit 3 that generates an output according to the operation / non-operation of the oscillating circuit 2 is used ( See, for example, Japanese Patent Laid-Open No. 3-292978). Specifically, this device has a configuration as shown in FIG. 8, and the oscillator circuit 2 controls the collector current of the oscillating transistor Q ₁ by a current mirror circuit composed of a pair of transistors Q ₂ and Q ₃ and an LC. It is of a tuning type that is fed back to the base of the transistor Q ₁ via the resonance circuit 1 and the diode-connected transistor Q ₄ . Therefore, if such a metal ball passes near the coil L ₁ constituting the LC resonance circuit 1, the feedback amount in the oscillation circuit 2 is changed according to the distance between the coil L ₁ and the metal balls, the metal balls When approaching, the amount of feedback decreases due to eddy current loss and the oscillation operation of the oscillation circuit 2 stops. The emitter of the transistor Q ₁ is connected the base of the transistor Q ₅ constituting the output circuit 3, the transistor Q ₅ is turned off when the emitter current of the transistor Q ₁ is stopped by stopping the oscillation operation of the oscillation circuit 2. The transistor Q ₅ constitutes an open collector type output circuit 3. A constant voltage is supplied to the oscillation circuit 2 by a power supply circuit 4 including a Zener diode ZD ₁ and a reverse connection protection diode D ₁ , and a transistor of the oscillation circuit 2 is supplied by a constant current circuit 5 including a constant current diode ID _2. A constant current is supplied to the base of Q ₁ .

[0003]

By the way, in the above configuration, the oscillation operation of the oscillation circuit 2 is stopped when the metal ball approaches, and when the metal ball is detected, the oscillation circuit 2 does not operate from the operating state. After shifting to the state, the non-operating state shifts to the operating state. Here, in order for the oscillation circuit 2 to shift from the non-operating state to the operating state, the starting condition of the oscillating operation must be satisfied, so that the oscillation state cannot be instantaneously changed to the metallic balls one after another. _When passing the vicinity of ₁ , the operation / non-operation switching of the oscillation circuit 2 may not be able to follow the passage of the metal ball. Further, since the oscillation operation of the oscillation circuit 2 is unstable immediately after the oscillation operation is started, the transistor Q ₅ of the output circuit 3 may not be turned on immediately after the oscillation operation is started. If the metal sphere passes at a shorter interval than that, it becomes impossible to follow the passage of the metal sphere.

Further, when the metal ball approaches the coil L ₁ and when it moves away from the coil L ₁ , there is a hysteresis in the relationship between the operation time and the non-operation time of the oscillation circuit 2 and the distance, and when the operation is changed to the non-operation. There is also a large variation in the difference (referred to as "hysteresis") between this distance and the distance when transitioning from non-motion to motion. That is, the conditions for starting and stopping the oscillating operation depend on the amount of current flowing to the coil L ₁ of the oscillating circuit 2, the resistance R ₁ connected to the emitter of the transistor Q ₁ , and the like. Stable operation is possible, but the operation is unstable when the oscillation circuit 2 is switched between operation and non-operation, and the conditions at the start and end of oscillation are not always constant. There is a problem that it is difficult to design for obtaining.

Now, as shown in FIG. 9, when two metal balls B pass through the sensor S (that is, the coil L ₁ ) continuously, as shown in FIG. Consider the case where the part of FIG. 9 is located near the center of the sensor S, and the case where one of the two metal balls B is located near the center of the sensor S as shown in FIG. 9B. Here, the magnetic field F generated by the sensor S is also shown in FIG. Metal ball B
9A, the oscillator circuit 2 must operate in the state of FIG. 9A, and the oscillator circuit 2 must not operate in the state of FIG. 9B. That is, it is necessary to set the operating conditions of the oscillation circuit 2 so that the oscillation operation is performed in the state of FIG. 9A and the oscillation operation is stopped in the state of FIG. 9B. However, as shown in FIG. 10, in the state of FIG. 9A, the conditions for stopping and starting the oscillation (see FIG.
The vertical axis indicates the emitter current of the transistor Q ₁ ) is not constant (the state of FIG. 9A is indicated by A and the state of FIG. 9B is indicated by B). There are cases where can be detected and cases where can not be detected. For example, if the oscillator circuit 2 operates as shown by the solid line in FIG.
Since the oscillating operation of the oscillating circuit 2 is stopped in a state closer to the state of FIG. 9 (b) than in the state of FIG. 9 (a), the continuously passing metal balls B can be separated and recognized. If it operates as shown by the broken line, the two metal balls B cannot be separately detected even in the state of FIG. 9A when the metal balls B are in contact with each other. Further, in the operation indicated by the alternate long and short dash line in FIG. 10, there are cases where the state of FIG.

It is assumed that the metal ball B passes from right to left in FIG. 9, and at time t ₁ , the center portion of the left metal ball B of the two metal balls B passes through the center portion of the sensor S, Time t ₂
9A, the state of FIG. 9B at time t ₃ and the state without the metal ball B at time t ₄ , the input to the output circuit 3 is as shown in FIG. 11, the solid line operation is as shown by the solid line in FIG. 11, whereas the solid line operation in FIG. 10 is as shown by the dashed line in FIG. That is, there is no problem if it operates as shown by the solid line in FIG. 10, but if it operates as shown by the alternate long and short dash line, the metal sphere cannot be detected reliably and reliably.

The present invention is intended to solve the above problems, and an object of the present invention is to provide a metal ball detecting apparatus capable of surely detecting even when a metal ball passes continuously.

[0008]

According to a first aspect of the present invention, there is provided an oscillation circuit having an LC resonance circuit arranged in the vicinity of a passage of a metal ball, and a pair of connection terminals depending on an output level of the oscillation circuit. The oscillator circuit is provided with an output circuit for increasing or decreasing the amount of passing current between them, and a constant current circuit for keeping the current supplied from the external power supply connected to the connection terminal to the oscillator circuit constant. It is characterized in that the operating point is set so that the output level is sometimes lowered due to eddy current loss.

According to a second aspect of the present invention, the output circuit includes a comparator, and the passing current amount is set in two stages depending on the presence or absence of the metal ball. According to a third aspect of the invention, the output circuit includes a comparator having hysteresis, and the passing current amount is set in two stages depending on the presence or absence of the metal ball.

[0010]

According to the structure of the invention of claim 1, the operation of the oscillation circuit is not stopped by the presence or absence of the metal ball, and only the output level of the oscillation circuit is changed by the presence or absence of the metal ball. Since there is no unstable operation due to switching between starting and stopping, even if the metal balls pass continuously, the metal balls can be individually recognized by the change in the passing current between the connection terminals. Will be possible. Here, since a constant current is supplied to the oscillation circuit through a constant current circuit, the oscillation operation does not become unstable even if the inflow current between the connection terminals changes, and only the passing current at the output terminal changes. It is possible to change the current flowing into the connection terminal depending on the presence or absence of the metal ball.

According to the second aspect of the invention, since the comparator is provided in the output circuit, the change in the inflow current to the connection terminal due to the presence or absence of the metal ball is binarized, and the inflow current to the connection terminal is changed. The presence or absence of the metal sphere due to the change can be easily identified. According to the configuration of the invention of claim 3, since the comparator is provided in the output circuit and the comparator is provided with hysteresis, the binarization is performed so that the change of the current flowing into the connection terminal corresponds to the presence or absence of the metal ball. In addition, output chattering due to recoil at the time of collision between metal balls does not occur, and the metal balls can be stably detected.

[0012]

【Example】

(Embodiment 1) In this embodiment, as shown in FIG. 1, an oscillation circuit 2 including an LC resonance circuit 1 as in the conventional configuration, and an output circuit 3 that obtains an output according to the oscillation operation of the oscillation circuit 2. With. The main difference from the conventional configuration is that the constant current circuit 6 supplies a constant current to the oscillator circuit 2, and the oscillator circuit 2 is configured according to the distance between the coil L ₁ forming the LC resonance circuit ₁ and the metal ball. This is the point that the output circuit 3 is operated by the change in the output.

A specific circuit is shown in FIG.
The oscillation circuit 2 is a transistor Q for oscillation. ₁Base-Emi
The LC resonance circuit 1 is connected between the
C resonance circuit 1 is a pair of capacitors C connected in series.₂,
C₃And coil L₁And a parallel resonant circuit including.
Further, the oscillator circuit 2 includes a pair of transistors Q₂, Q₃Yo
With a current mirror circuit
Q₂Resistor R is added to the emitter and collector of₂, R
₃Connected in series circuit and the other transistor Q₃D
Resistance R to Mitter_FourAnd connect the LC resonance circuit 1 to the collector.
Connected series circuit and transistor Q₁Connected to the emitter of
Continued resistance R₁And capacitor C₁Parallel circuit with
Jista Q₁The emitter-collector and the series circuit of
Connected in parallel to this parallel circuit from the constant current circuit 6
A constant current is supplied. Transistor Q₃The emitter of
Is the feedback resistor R_FiveThrough the capacitor C₂, C₃Contact
It is also connected to the continuation point. The constant current circuit 6 is a constant current diode
ID₁And doubles as a diode to prevent reverse connection.
It Further, the output of the constant current circuit 6 is a Zener diode.
ZD₁Is made constant by the constant voltage circuit 4 consisting of
It The output circuit 3 is a transistor Q_FiveAnd emitter resistance
R₆And this transistor Q_FiveEmitter-this
And emitter resistance R₆The series circuit with is a connection terminal
t₁, T₂Connected between both ends of.

According to the above construction, when the metal ball approaches the coil L ₁ of the LC resonance circuit 1, the output amplitude (that is, the emitter current) of the oscillation circuit 2 decreases due to the eddy current loss.
The voltage across the resistor R ₁ connected to the emitter of the transistor Q ₁ is smoothed by the capacitor C ₁ and biases the transistor Q ₅ . When there is no metal ball near the coil L ₁ , eddy current loss does not occur, so that the emitter current of the transistor Q ₁ increases and the current flowing through the transistor Q ₅ increases. Therefore, the connection terminal t
_The current flowing into ₁ and t ₂ is the sum of the current flowing into the constant current circuit 6 and the current flowing through the transistor Q ₅ .
On the other hand, when the metal ball approaches, the emitter current decreases and the transistor Q ₅ turns off, and the current flowing into the connection terminals t ₁ and t ₂ becomes substantially equal to the current flowing into the constant current circuit 6.

As described above, the inflow currents to the connection terminals t ₁ and t ₂ change depending on the presence or absence of the metal ball. Therefore, if a circuit for detecting the change in current is connected to the connection terminals t ₁ and t ₂ , the change in current will occur. The approach of metal balls can be detected. Further, the oscillation circuit 2 is set so that the operation does not stop even when the metal ball approaches, and stable operation is possible because the oscillation operation is not stopped. That is, the oscillator circuit 2 does not operate or not operate depending on the presence or absence of a metal ball as in the conventional configuration, but as shown in FIG. 3, in the state of FIG. 9A, the output level of the oscillator circuit 2 (transistor Q ₁ The emitter current is relatively large, the output level decreases as the metal sphere approaches, and the output level is sufficiently reduced in the state of FIG. 9B. Therefore, to determine the states of FIG. 9 (a) and FIG. 9 (b),
The threshold may be set as appropriate within the range shown by the shaded area in FIG.

(Embodiment 2) In the present embodiment, as shown in FIG. 4, the output circuit 3 is configured as a comparator, which comprises a transistor Q ₆ and resistors R _{7 to} R _7.
It is composed of ₉ and. The resistors R ₇ and R ₈ divide the voltage across the Zener diode ZD ₁ to generate a reference voltage, and the reference voltage is applied to the base of the transistor Q ₆ . The emitter of the transistor Q ₆ is connected to the emitter of the transistor Q ₁ of the oscillation circuit 2 via the resistor R _9, and the voltage across the capacitor C ₁ is compared with the reference voltage. Further, the collector of the transistor Q ₆ has a connection terminal t ₁
Connected to.

According to the above configuration, the voltage across the capacitor C ₁ is set to be higher than the reference voltage when there is no metal ball, the transistor Q ₆ is off, and the connection terminals t ₁ and t _{2 are} connected. Only the current to the constant current circuit 6 flows into the. When a metal ball is present, the voltage across the capacitor C ₁ becomes lower than the reference voltage and the transistor Q ₆ is turned on. As a result, the inflow current to the connection terminals t ₁ and t ₂ increases. . Even with this configuration, the first embodiment
Similarly, since the oscillation circuit 2 continues to operate regardless of the distance from the metal ball, stable operation is possible without switching between operation and non-operation of the oscillation circuit 2 unlike the conventional configuration.
Further, since the output circuit 3 is a comparator, binary signals can be output from the connection terminals t ₁ and t ₂ .
However, in the present embodiment, contrary to the first embodiment, the current flowing into the connection terminals t ₁ and t ₂ increases when the metal balls are present.

[0018] That is, in the configuration of the present embodiment, when the two metal balls continuously passes by the sensor S (coil L _1), as shown in FIG. 5, one of the metal at time t ₁ The center of the sphere and the center of the sensor S substantially coincide with each other, the center of the sensor S between the two metal spheres substantially coincides with each other at time t ₂ , and the center of the other metal sphere substantially coincides with the center of the sensor S at time t _3. If they coincide with each other and both metal balls are separated from the sensor S at time t ₄ , the output (emitter current) of the oscillation circuit 2 changes as shown by the broken line in FIG. Further, the connection terminals t ₁ , t
_The current flowing into ₂ changes as shown by the solid line in FIG. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 3) In this embodiment, an output circuit 3 is used.
In the output circuit 3 of the first embodiment, as shown in FIG.
Transistor Q_FiveBetween the oscillator and the oscillation circuit 2 as in the second embodiment
Transistor Q ₆Is equipped with a comparator
In addition, the comparator has a configuration with hysteresis.
It Therefore, the transistors that make up the comparator
Q₆The base of the Zener diode ZD₁Both ends of
Pressure resistance R₇, R₈The reference voltage obtained by dividing
Transistor Q₆The emitter is a resistor R₉Through
Langista Q₁Connected to the emitter of
Star Q₆Is a resistor R_TenOf the constant current circuit 6 via
Connected to the output. Transistor Q₁Fixed for collectors
A resistor R is provided between the output terminal of the current circuit 6 and the output terminal.₁₁When is connected
Resistance R₇, R₈Resistance R between the connection point₁₂Connected
Is done. The hysteresis of the comparator is the resistance R ₁₁, R
₁₂Given by. Transistor Q₆Is a collector
Langista Q_FiveConnected to the base of the transistor Q₆
Is turned on, the transistor Q_FiveTurns off.

According to the above structure, when the metal ball is present near the coil L ₁ , the output level (emitter current) of the oscillation circuit 2 is lowered and the transistor Q ₆ is turned on and the transistor Q ₅ is turned off. That is, the connection terminals t ₁ , t
_The current flowing into ₂ is only the current flowing into the constant current circuit 6. On the other hand, when there is no metal ball, the output level of the oscillation circuit 2 increases, so that the transistor Q ₆ is turned off and the transistor Q ₅ is turned on, so that the connection terminal t ₁ ,
The current flowing into t ₂ increases. In short, the inflow current to the connection terminals t ₁ and t ₂ changes in the same direction as in Example 1 depending on the presence or absence of the metal ball. However, the current change in this embodiment is binary. Further, since the comparator is provided with hysteresis, once the transistor Q ₆ is turned on or off, it is difficult to reverse the on / off state, so that even if the metal ball bounces a little, it should not be erroneously detected. There is. Other configurations and operations are the same as those of the first embodiment.

[0021]

According to the invention of claim 1, the operation of the oscillation circuit is not stopped by the presence or absence of the metal ball, and the output level of the oscillation circuit is only changed by the presence or absence of the metal ball. Therefore, the oscillation operation is started. Since the unstable operation accompanying switching between stop and stop does not occur, as a result, even when the metal balls pass continuously, it is possible to recognize each metal ball individually due to the change in the passing current between the connection terminals. Has the advantage that Also, since a constant current is supplied to the oscillation circuit through the constant current circuit, the oscillation operation does not become unstable even if the inflow current between the connection terminals changes, and only the passing current at the output terminal changes. There is an advantage that the current flowing into the connection terminal can be changed depending on the presence or absence of the metal ball.

According to the second aspect of the invention, since the comparator is provided in the output circuit, the change in the inflow current to the connection terminal due to the presence or absence of the metal ball is binarized, and the metal ball due to the change in the inflow current to the connection terminal. There is an advantage that it is easy to identify the presence or absence of. According to the invention of claim 3, since the output circuit is provided with the comparator and the comparator is provided with hysteresis, the change of the current flowing into the connection terminal is binarized so as to correspond to the presence or absence of the metal ball, and There is an advantage that output chattering due to recoil at the time of collision between metal balls does not occur and the metal balls can be detected stably.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment.

FIG. 2 is a circuit diagram showing a first embodiment.

FIG. 3 is an operation explanatory diagram of the first embodiment.

FIG. 4 is a circuit diagram showing a second embodiment.

FIG. 5 is an operation explanatory diagram of the second embodiment.

FIG. 6 is a circuit diagram showing a third embodiment.

FIG. 7 is a block diagram showing a conventional example.

FIG. 8 is a circuit diagram showing a conventional example.

FIG. 9 is an operation diagram showing a positional relationship between a metal ball and a sensor.

FIG. 10 is an operation explanatory diagram of a conventional example.

FIG. 11 is an operation explanatory diagram of a conventional example.

[Explanation of symbols]

1 LC resonance circuit 2 Oscillation circuit 3 Output circuit 6 Constant current circuit B Metal ball L ₁ coil S Sensor t ₁ , t ₂ connection terminal

Claims (3)

[Claims] 1. An oscillation circuit including an LC resonance circuit arranged in the vicinity of a passage of a metal ball, and an output circuit for increasing or decreasing a passing current amount between a pair of connection terminals according to an output level of the oscillation circuit. , A constant current circuit that keeps the current supplied to the oscillation circuit from an external power source connected to the connection terminal constant, and the oscillation circuit reduces the output level due to eddy current loss when the metal ball approaches the LC resonance circuit. An operating point is set on the metal ball detection device. 2. The metal ball detecting device according to claim 1, wherein the output circuit includes a comparator, and the passing current amount is set in two stages depending on the presence or absence of the metal ball. 3. The metal ball detecting device according to claim 1, wherein the output circuit includes a comparator having hysteresis, and the passing current amount is set in two stages depending on the presence or absence of the metal ball.