JPH0818430A - Magnetic switch - Google Patents

Abstract

PURPOSE:To provide the inexpensive magnetic switch of simple constitution capable of being turned on and off by the minute magnetic field of several oersteds by using an oscillation circuit for which a cobalt based amorphous wire is used as an L load. CONSTITUTION:This magnetic switch 10 is constituted of the oscillation circuit 11 for which the cobalt based amorphous wire is made the L load, a rectifier circuit 12 for rectifying the oscillation voltage and a discrimination circuit 13 for outputting ON signals when a DC voltage from the rectifier circuit 12 is larger than a reference voltage. Thus, by the minute magnetic field of several oersteds, the high frequency resistance of the amorphous wire which is the L load is substantially decreased, oscillation continuation conditions are satisfied, the oscillation voltage rises and thus, the ON signals or OFF signals are outputted by a control circuit. The excellent magnetic switch whose cost is reduced by the simple constitution is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic switch that is turned on / off based on the strength of magnetic flux.

[0002]

2. Description of the Related Art Conventionally, for example, a reed switch or a semiconductor switch is known as such a magnetic switch.

The reed switch mechanically operates the reed switch piece based on the strength of the magnetic flux. Further, the semiconductor switch is electrically operated by utilizing the magneto-electric conversion effect of the Hall element and the MR element.

[0004]

However, such a magnetic switch has the following problems. That is, since both the reed switch and the semiconductor switch require a magnetic field of several tens oersteds or more for on / off operation, there is a problem that they cannot be turned on / off by a minute magnetic field.

Further, particularly in a semiconductor switch, since the detection element, that is, the Hall element and the MR element are non-magnetic materials, a relatively strong magnetic field is applied or a magnetic flux is applied to the detection element for switching operation. To concentrate
A problem is that a magnetizing steel such as ferrite is required, and on / off operation is discriminated based on the output voltage levels of these Hall element and MR element, so that a discriminating circuit requires a stabilized power supply. was there.

In view of the above points, an object of the present invention is to provide a magnetic switch that can be turned on and off by a minute magnetic field of about several oersteds and can be reduced in cost with a simple structure.

[0007]

According to the present invention, the above object is achieved by an oscillation circuit having a cobalt-based amorphous wire as an L load, and a control circuit for determining ON / OFF based on the oscillation voltage of the oscillation circuit. This is achieved by a magnetic switch, which is characterized in that it is constructed.

In the magnetic switch according to the present invention, preferably, the control circuit includes a rectifying circuit for rectifying the oscillation voltage of the oscillating circuit, and a discriminating circuit for outputting an ON signal when the DC voltage from the rectifying circuit is higher than the reference voltage. It consists of

In the magnetic switch according to the present invention, preferably, the control circuit comprises a high frequency amplifier for amplifying the oscillation voltage of the oscillation circuit and a detection circuit for detecting the AC voltage from the high frequency amplifier.

In the magnetic switch according to the present invention, the L load is preferably composed of a coil wound around an amorphous wire.

In the magnetic switch according to the present invention, the L load preferably comprises a linear amorphous wire and an auxiliary coil connected in series to the amorphous wire.

[0012]

According to the above construction, the cobalt-based amorphous wire is used as the L load, and the inductance and the high frequency resistance of the cobalt-based amorphous wire change remarkably depending on the strength of the magnetic field of about several oersteds. The high-frequency resistance of the oscillating circuit is drastically reduced from hundreds of tens Ω to tens of Ω by the action of a minute magnetic field of about several oersteds on the cobalt-based amorphous wire that is the load. Therefore, the oscillation continuation condition in the oscillation circuit is satisfied, the oscillation continues, and the oscillation voltage increases. Accordingly, by comparing the oscillation voltage of the oscillation circuit with the reference voltage by the control circuit, the ON signal is output from the control circuit when the oscillation voltage is higher than the reference voltage.

If the control circuit is composed of a rectifying circuit for rectifying the oscillating voltage of the oscillating circuit and a discriminating circuit for outputting an ON signal when the DC voltage from the rectifying circuit is higher than the reference voltage, the oscillation After the oscillating voltage of the circuit is converted into a DC voltage by the rectifying circuit, the discriminating circuit compares it with the reference voltage. When the DC voltage is higher than the reference voltage, the discriminating circuit outputs an ON signal.

When the control circuit comprises a high frequency amplifier for amplifying the oscillation voltage of the oscillation circuit and a detection circuit for detecting the AC voltage from the high frequency amplifier, the oscillation voltage of the oscillation circuit is controlled by the high frequency amplifier. A change in the oscillation voltage due to the AC magnetic field can be detected by the detection circuit from the amplified AC voltage from the high frequency amplifier. As a result, when the oscillation voltage is higher than the reference voltage, the detection circuit outputs an ON signal.

When the L load is composed of a coil wound around an amorphous wire, this coil is
By having an equivalent circuit in which a coil and high frequency resistance are connected in series, the high frequency resistance and inductance of the amorphous wire are greatly reduced by the magnetic field,
The oscillation continuation condition of the oscillation circuit is satisfied.

When the L load is composed of a linear amorphous wire and an auxiliary coil connected in series with the amorphous wire, the high frequency resistance of the amorphous wire connected in series with the auxiliary circuit is affected by the magnetic field. By greatly reducing, the oscillation sustaining condition of the oscillation circuit is satisfied.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. FIG. 1 shows an embodiment of a magnetic switch according to the present invention. That is, in FIG. 1, the magnetic switch 10 includes an oscillating circuit 11 using a cobalt-based amorphous wire as an L load, a rectifying circuit 12 for rectifying an oscillating voltage of the oscillating circuit 11, and a DC voltage from the rectifying circuit 12 as a reference. The determination circuit 13 outputs an ON signal when the voltage is larger than the voltage. Here, the rectifying circuit 1
2 and the discriminating circuit 13 constitute a control circuit 14 which discriminates ON / OFF based on the oscillation voltage of the oscillation circuit 11.

The oscillation circuit 11 includes a coil 11a wound around a cobalt-based amorphous wire and an oscillation transistor 11b. The coil 11a has one end connected to the B power supply and the other end connected to the collector of the oscillation transistor 11b. The base of the oscillation transistor 11b is connected to the B power source through the resistor 11c, and is also grounded through the capacitor 11d, the diode 11e, and the resistor 11f. Further, the emitter of the oscillation transistor 11b is
It is connected to the collector via the capacitor 11g, and is also connected to the ground via the resistor 11h and the capacitor 11i.

As shown in FIG. 2A, the coil 11a is constructed by winding a coil of several tens of turns around a cobalt-based amorphous wire of φ20 μm to φ100 μm. , Fig. 2
As shown in (B), it is an equivalent circuit in which a coil and a high frequency resistor are connected in series. As a result, the inductance L of the coil and the resistance value R of the high frequency resistance in this equivalent circuit change with respect to the magnetic field as shown in FIG. Therefore, the resistance value R of the high frequency resistance is greatly reduced from, for example, one hundred and several tens Ω to ten and several Ω due to the increase of the magnetic field of several oersteds from the off region to the on region. In addition, in the case of FIG. 2A, even if the length of the amorphous wire is several millimeters,
The high-frequency resistance may change significantly with a minute magnetic field.

When the resistance value R of the high frequency resistance is thus reduced, the oscillation continuation condition in the oscillation circuit 11 is satisfied, and the oscillation circuit 11 continues to oscillate.
At this time, the emitter voltage of the oscillation transistor 11b, that is, the oscillation voltage, greatly increases as the magnetic field from the off region to the on region increases as shown in FIG.

The rectifying circuit 12 is composed of a diode 12a connected in series to the emitter of the oscillation transistor 11b of the oscillation circuit 11, a resistor 12b and a capacitor 12c connected between the output side of the diode 12a and the ground. ing. As a result, the oscillating voltage of the emitter of the oscillating transistor 11b of the oscillating circuit 11 is
It is rectified by the second diode 12a and smoothed by the resistor 12b and the capacitor 12c.

Further, the discrimination circuit 13 is composed of a discrimination transistor 13a. The transistor 13
The base a is connected to the output side of the diode 12a of the rectifier circuit 12, the collector is connected to the B power source through the resistor 13b, the emitter is grounded, and the collector is the external output terminal 15 It is connected to the.

The magnetic switch 10 according to the embodiment of the present invention comprises:
The coil 1 of the oscillator circuit 11 is configured as described above.
When the magnetic field does not act on 1a, the magnetic flux of the magnetic field is not focused on the amorphous wire and the high frequency resistance of the coil 11a is relatively large, so that the Q of the L load is low, and the oscillation circuit 11 has a continuous oscillation condition. Not fulfilled. Therefore, the oscillation circuit 11 does not oscillate, and the oscillation voltage of the oscillation transistor 11b is a relatively low voltage in the off region on the left side in FIG. Therefore, the DC voltage rectified and smoothed by the rectifier circuit 12 is also relatively low. Thus, since the base voltage input to the transistor 13a of the determination circuit 13 is low, the transistor 13a remains off. Therefore, an H level signal, that is, an OFF signal, is output from the external output terminal 15.

When a magnetic field is applied to the coil 11a of the oscillation circuit 11, the amorphous wire itself has a high magnetic permeability, so that the magnetic flux of this magnetic field is focused on the amorphous wire.
As shown in FIG. 3, the resistance value R of the high frequency resistance of 1 is significantly decreased in the ON region. Therefore, the Q of the L load becomes high, the oscillation circuit 11 satisfies the oscillation continuation condition, and the oscillation circuit 11 oscillates. As a result, the oscillation voltage of the oscillation transistor 11b becomes relatively high in the ON region on the right side in FIG. 4, so that the DC voltage rectified and smoothed by the rectification circuit 12 also becomes high. Thus, the base voltage input to the transistor 13a of the discriminating circuit 13 becomes high and the transistor 13a is turned on. Therefore, the external output terminal 15 outputs an L level signal, that is, an ON signal.

In this case, the transistor 1 of the discrimination circuit 13
The oscillation transistor 11b is connected from the B power source to the base of 3a.
The emitter voltage of is supplied. Therefore, even if the supply voltage of the B power supply changes due to drift, the threshold value for the on / off determination by the transistor 13a does not change. Also, the high frequency resistance of amorphous wire is
The magnetic switch 10 has excellent temperature characteristics because it changes stably with respect to temperature in the range of −180 ° C. to 180 ° C.

FIG. 5 shows the magnetic switch 1 according to the above embodiment.
The modification of the oscillation circuit 11 in 0 is shown. 5, the oscillation circuit 20 includes a linear amorphous wire 21 and an auxiliary coil 22 connected in series to the amorphous wire 21 instead of the coil 11a of FIG. The auxiliary coil 22 is added because the inductance component of the amorphous wire 21 is insufficient as an L load for the oscillation continuation condition. As a result, similar to the oscillator circuit 11, when the magnetic field does not act on the amorphous wire 21 of the oscillator circuit 20, the oscillator circuit 20 does not oscillate, and when the magnetic field acts on the amorphous wire 21 of the oscillator circuit 20. The oscillation circuit 20 oscillates. Thus, the oscillating voltage of the oscillating transistor 11b is similarly converted to the rectifying circuit 1
By rectifying and smoothing at 2, and making a determination by the determination circuit 13, an ON / OFF signal can be output from the external output terminal 15 of the determination circuit 13.

FIG. 6 shows another embodiment of the magnetic switch according to the present invention. In FIG. 6, the magnetic switch 30
Is composed of an oscillating circuit 31 using a cobalt-based amorphous wire as an L load, a high frequency amplifier 32 for amplifying an oscillating voltage of the oscillating circuit 31, and a detecting circuit 33 for detecting an AC voltage from the high frequency amplifier 32. There is. here,
The high-frequency amplifier 32 and the detection circuit 33 constitute a control circuit 34 which makes an ON / OFF determination based on the oscillation voltage of the oscillation circuit 31.

The oscillation circuit 31 includes a coil 31a wound around a cobalt-based amorphous wire and an oscillation transistor 31b. The coil 31a has one end connected to the B power supply and the other end connected to the collector of the oscillation transistor 31b. The base of the oscillation transistor 31b is connected to the B power source through a resistor 31c, and is also grounded through a capacitor 31d, a diode 31e, and a resistor 31f. Further, the emitter of the oscillation transistor 31b is
It is connected to the collector through the capacitor 31g, and is also grounded through the resistor 31h and the capacitor 31i.

As in the case of the magnetic switch 10 of FIG. 1, the coil 31a has a diameter of φ20 as shown in FIG. 2 (A).
It is configured by winding a coil of several tens of turns around a cobalt-based amorphous wire of μm to φ100 μm.

Further, the high frequency amplifier 32 is the oscillator circuit 31.
The relatively low oscillation voltage from the emitter of the oscillation transistor 31b is amplified and output to the detection circuit 33. The detection circuit 33 detects an AC magnetic field from the oscillation voltage amplified by the high frequency amplifier 32.

According to the magnetic switch 30 having such a configuration, when the magnetic field is not acting on the coil 31a of the oscillation circuit 31, the magnetic flux of the magnetic field is not focused on the amorphous wire, and the high frequency resistance of the coil 31a is increased. Because it's relatively large,
Since the Q of the L load is low, the oscillation circuit 31 does not satisfy the oscillation continuation condition. Therefore, the oscillation circuit 31 does not oscillate, and the oscillation voltage of the oscillation transistor 31b is a relatively low voltage in the off region on the left side in FIG. Therefore, the oscillation voltage amplified by the high frequency amplifier 32 is also relatively low. Thus, since the detection circuit 33 does not detect the AC magnetic field, the OFF signal is output from the external output terminal 34.

Here, when a magnetic field is applied to the coil 31a of the oscillator circuit 31, since the amorphous wire itself has a high magnetic permeability, the magnetic flux of this magnetic field is focused on the amorphous wire.
As shown in FIG. 3, the resistance value R of the high frequency resistance of 1 is significantly decreased in the ON region. Therefore, the Q of the L load becomes high, the oscillation circuit 31 satisfies the oscillation continuation condition, and the oscillation circuit 13 oscillates. As a result, the oscillation voltage of the oscillation transistor 31b becomes relatively high in the ON region on the right side in FIG. 4, so that the oscillation voltage amplified by the high frequency amplifier 32 also becomes high. Thus, the detection circuit 3
3 detects an AC magnetic field and outputs an ON signal.

[0033]

As described above, according to the present invention, L
Since a cobalt-based amorphous wire is used as the load, a small magnetic field of about several oersteds acts on the cobalt-based amorphous wire, which is an L load, so that the high frequency resistance of the oscillator circuit is in the range of hundreds of tens of Ω. It is significantly reduced to ten and several Ω, the oscillation continuation condition in the oscillation circuit is satisfied, and the oscillation voltage is increased. Accordingly, by comparing the oscillation voltage of the oscillation circuit with the reference voltage by the control circuit, the ON signal is output from the control circuit when the oscillation voltage is higher than the reference voltage.

Therefore, the high frequency resistance of the amorphous wire, which is the L load, is greatly reduced by the minute magnetic field of about several oersteds, the oscillation continuation condition is satisfied, and the oscillation voltage rises. A signal or an off signal could be output.

If the control circuit is composed of a rectifying circuit for rectifying the oscillating voltage of the oscillating circuit and a discriminating circuit for outputting an ON signal when the DC voltage from the rectifying circuit is higher than the reference voltage, the oscillation is generated. After the oscillating voltage of the circuit is converted into a DC voltage by the rectifying circuit, the discriminating circuit compares it with the reference voltage. When the DC voltage is higher than the reference voltage, the discriminating circuit outputs an ON signal.

When the control circuit is composed of a high frequency amplifier for amplifying the oscillation voltage of the oscillation circuit and a detection circuit for detecting the AC voltage from the high frequency amplifier, the oscillation voltage of the oscillation circuit is controlled by the high frequency amplifier. A change in the oscillation voltage due to the AC magnetic field can be detected by the detection circuit from the amplified AC voltage from the high frequency amplifier. As a result, when the oscillation voltage is higher than the reference voltage, the detection circuit outputs an ON signal.

When the L load is composed of a coil formed by winding an amorphous wire, this coil is
By having an equivalent circuit in which a coil and high frequency resistance are connected in series, the high frequency resistance and inductance of the amorphous wire are greatly reduced by the magnetic field,
The oscillation continuation condition of the oscillation circuit is satisfied.

When the L load is composed of a linear amorphous wire and an auxiliary coil connected in series with the amorphous wire, the high frequency resistance of the amorphous wire connected in series with the auxiliary circuit is affected by the magnetic field. By greatly reducing, the oscillation sustaining condition of the oscillation circuit is satisfied.

Thus, according to the present invention, it is possible to provide an extremely excellent magnetic switch which can be turned on and off by a minute magnetic field of about several oersteds and whose cost can be reduced by a simple structure.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a magnetic switch according to the present invention.

2 shows an L load in the magnetic switch of FIG. 1,
(A) is a schematic diagram and (B) is an equivalent circuit diagram.

FIG. 3 is a graph showing changes in the L load of FIG. 2 due to a magnetic field.

FIG. 4 is a graph showing a change in output voltage of the oscillation circuit of the magnetic switch of FIG. 1 due to a magnetic field.

5 is a circuit diagram showing a modified example of the oscillation circuit of the magnetic switch of FIG.

FIG. 6 is a circuit diagram showing another embodiment of the magnetic switch according to the present invention.

[Explanation of symbols]

 10, 30 Magnetic switch 11, 20, 31 Oscillation circuit 11a, 31a Coil 11b, 31b Oscillation transistor 12 Rectifier circuit 13 Discrimination circuit 13a Discrimination transistor 14 Control circuit 15, 34 External output terminal 21 Cobalt-based amorphous wire 22 Auxiliary coil 32 High frequency Amplifier 33 Detection circuit

Claims (5)

[Claims] 1. A magnetic switch comprising an oscillating circuit using a cobalt-based amorphous wire as an L load, and a control circuit for discriminating between ON and OFF based on an oscillating voltage of the oscillating circuit. 2. The control circuit comprises a rectifying circuit for rectifying the oscillation voltage of the oscillating circuit and a discriminating circuit for outputting an ON signal when the DC voltage from the rectifying circuit is higher than the reference voltage. The magnetic switch according to claim 1, wherein 3. The control circuit comprises a high frequency amplifier for amplifying an oscillation voltage of the oscillation circuit and a detection circuit for detecting an AC voltage from the high frequency amplifier. Magnetic switch. 4. The magnetic switch according to claim 1, wherein the L load is composed of a coil wound around an amorphous wire. 5. The magnet according to claim 1, wherein the L load is composed of a linear amorphous wire and an auxiliary coil connected in series to the amorphous wire. switch.