JP2000188558A - Reception device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize and integrate a device by giving a driving AC signal to a magnetic impedance effect element, rectifying the mix signal of a received radio wave signal and the driving AC signal and separating and extracting the received radio signal from the mix signal. SOLUTION: A driving AC signal is given to a magnetic impedance effect element 11b by a driving circuit 11a and output voltage by impedance is generated on both ends of the magnetic impedance effect element 11b. When the radio signal of an AM wave reaches a reception device, the amplitude of output voltage on both ends of the magnetic impedance effect element 11b changes in accordance with the change of the amplitude of a magnetic component in the radio signal. Since the amplitude of output voltage on both ends of the magnetic impedance effect element 11b changes in accordance with the change of the amplitude of a carrier, outputs from both ends of the magnetic impedance effect element 11b become the mix signals of the received radio signal of a carrier and the driving AC signal and are inputted to a rectifying circuit 11c. They are inputted to a frequency discriminator 11d after they are rectified and the driving AC signal is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving apparatus having an antenna section, a tuning circuit, and a detection circuit, and more particularly, to reducing the size of the antenna section by using a magneto-impedance effect element in the antenna section. The present invention relates to a receiving device capable of reducing the size of the entire receiving device.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a conventional receiving apparatus. In the receiving device of FIG. 7, a radio signal is converted into an electric signal by the antenna unit 1. In the case of a medium-wave receiving device, the antenna unit 1 is formed by a winding coil having a high-permeability magnetic core such as ferrite as a core. A magnetic field component of a radio wave is detected by an antenna formed by a winding coil of a ferrite core.

[0003] The winding coil comprises a primary winding 1a and a secondary winding 1b, and both coils are inductively coupled. The tuning circuit 2 is formed by connecting the primary winding 1a and the tuning variable condenser 2a in parallel. The frequency of the received signal is selected by the tuning circuit 2. The frequency-selected received signal is taken out of the secondary winding 1b and amplified by the high frequency amplifier circuit 3. The output of the high-frequency amplifier circuit 3 is
This is a mixed signal of the carrier and the audio signal, and the carrier is removed from the mixed signal by the detection circuit 4 at the subsequent stage, and the audio signal is detected. The detected audio frequency signal is amplified by a low frequency amplifier circuit 5 as necessary, and output as voice or music by a speaker 6.

[0004]

However, the conventional winding coil having a ferrite core used in the antenna section 1 has a disadvantage that it is difficult to reduce the size.
In general, when a core having a high magnetic permeability is used as a core and excited in the length direction of the core, a demagnetizing field is formed in the core. Therefore, when the core is shortened to 10 mm or less, the magnetic field detection sensitivity is rapidly deteriorated. For this reason, the conventional ferrite core antenna generally has a length of about 50 mm or more. In addition, ferrite is fragile due to the nature of the material, and has a difficulty in handling during manufacture.

[0005] Further, the circuits such as the detection circuit 4 and the amplification circuits 3 and 5 can be easily reduced in size by integration into an integrated circuit. However, since the length of the antenna unit 1 is longer than a certain length as described above, it is difficult to reduce the size of the entire device.

An object of the present invention is to solve the above-mentioned conventional problems, and it is an object of the present invention to provide a receiving apparatus which can reduce the size of an antenna unit and make the whole apparatus smaller and more integrated.

[0007]

According to the present invention, there is provided a receiving apparatus including an antenna unit, a tuning circuit, and a detection circuit, wherein the antenna unit includes a magneto-impedance element, and a magneto-impedance element. A driving circuit that supplies a driving AC signal to the rectifying circuit, a rectifying circuit that rectifies a mixed signal of the received radio signal and the driving AC signal given by the driving circuit, and a frequency discriminator that separates and extracts the received radio signal from the mixed signal. It is characterized by the following.

The magneto-impedance effect refers to the following phenomenon. MH on ribbon or wire magnetic material
When an alternating current in the z band is applied, an output voltage is generated at both ends of the magnetic body based on the impedance inherent in the material. When an external magnetic field is applied in the length direction of the magnetic body in this state, the impedance of the magnetic body changes even if the external magnetic field is a weak magnetic field of about several gauss, and the amplitude of the output voltage corresponds to the strength of the external magnetic field. And changes within a range of several tens of percent.

Since the element having the magneto-impedance effect is excited in the outer peripheral direction of the element, there is no demagnetizing field, and the magnetic permeability is increased by a slight rotation of the magnetization vector in the element length direction, that is, in the direction in which an alternating current flows. Changes rapidly. Therefore, the demagnetizing field in the length direction is small, and the length of the element is 1 mm.
Even if it is on the order, the magnetic field detection sensitivity hardly deteriorates.

Electrodes are formed at both ends of the magneto-impedance effect element for connection to the drive circuit. If the direction in which the drive AC signal flows is defined as a hard axis, the magnetic permeability increases in that direction. This is preferable because the detection sensitivity to an applied external magnetic field increases.

Further, when a bias magnetic field is applied to the magneto-impedance effect element in a direction in which the drive AC signal flows, a change in the output voltage across the magneto-impedance effect element corresponding to a change in the magnetic field component of the broadcast radio wave. It is agile and preferred.

The magneto-impedance effect element may be formed in a ribbon shape or a wire shape. Preferably, the frequency of the driving AC signal is higher than the frequency of the carrier of the received radio signal.

The magneto-impedance effect element does not exhibit a magneto-impedance effect unless the driving AC signal has a high frequency. The frequency of the driving AC signal needs to be at least several hundred kHz, but if the frequency of the driving AC signal is close to the frequency of the carrier of the received radio signal, the driving AC signal is removed from the mixed signal at a later stage. It becomes difficult. The frequency of medium-wave broadcasting is in a band higher than 500 kHz, but even if an attempt is made to lower the driving AC signal,
Since the difference between the frequency of the drive AC signal and the frequency of the received radio signal can be only a few hundred kHz at most, the high-pass filter
It becomes difficult to remove the driving AC signal. On the other hand, in order to increase the frequency of the driving AC signal higher than the frequency of the carrier of the received radio signal, the driving AC signal can be as high as the low-pass filter for removing the driving AC signal allows. In practice, the frequency of the driving AC signal may be several tens times the frequency of the received radio signal.

The magnetic material used in the magnetic impedance element of the present invention needs to be a ferromagnetic material having soft magnetic properties. In addition, the magnetic permeability μ must be high in a high frequency range of several tens MHz to several hundred MHz. In order to increase the magnetic permeability μ in the high frequency region, the specific resistance ρ must be large. Further, it is preferable that the magnetostriction constant λ is small so that external characteristics are not applied to the magneto-impedance effect element to deteriorate the magnetic characteristics. like this,
As the magnetic material, for example, the following materials can be used.

The composition formula is (Fe _1-a Co _a )
Consists _{100-xy (Si 1-b} B b) amorphous soft magnetic alloy represented by _x M _y, M is Cr, an element which includes either one or both of the Ru, a representative of the composition ratio , B is 0.
05 ≦ a ≦ 0.1, 0.2 ≦ b ≦ 0.8, x, y
Indicates that at% satisfies the relationship of 10 ≦ x ≦ 35 and 0 ≦ y ≦ 7.

In the above, if a exceeds the range of 0.05 ≦ a ≦ 0.1, the magnetostriction increases, which is not preferable. On the other hand, if b exceeds the range of 0.2 ≦ b ≦ 0.8, it becomes difficult to make the film amorphous, which is not preferable. Further, x is 10 ≦ x ≦
If it exceeds 35, it becomes difficult to form an amorphous layer, which is not preferable. If x> 35, the magnetic properties deteriorate, which is not preferable.

The composition formula is represented by Co _l Ta _m Hf _n,
It is composed of an amorphous soft magnetic alloy mainly composed of an amorphous structure, where l, m, and n are at% and 70 ≦ l ≦ 90, 5 ≦ m ≦
21, 6.6 ≦ n ≦ 15, 1 ≦ m / n ≦ 2.5.

[0018] In the Co _l Ta _m Hf _n based soft magnetic alloy of the saturation magnetic flux density Bs is dependent on the content of Co, in order to obtain a high saturation magnetic flux density Bs, that is 70 ≦ l is necessary. However, when l ≧ 90, the specific resistance ρ becomes low, which is not preferable.

Ta and Hf are elements for obtaining soft magnetic properties, and when 5 ≦ m ≦ 21 and 6.6 ≦ n ≦ 15, the soft magnetic property is such that the saturation magnetic flux density Bs is large and the specific resistance ρ is large. Material can be obtained. Hf is Co
It is also an element for eliminating the negative magnetostriction constant λ generated in the -Ta system. The magnetostriction constant λ is determined by the Ta content and Hf
Depends on the content ratio, and if it is within the range of 1 ≦ m / n ≦ 2.5, the magnetostriction constant λ can be satisfactorily eliminated.

The composition formula is represented by Fe _h M _i O _j, becomes an amorphous structure from the microcrystalline soft magnetic alloy consisting mainly,
M is one or more elements selected from Ti, Zr, Hf, V, Nb, Ta, W and rare earth elements;
h, i, j are at%, 45 ≦ h ≦ 70, 5 ≦ i ≦ 3
0, 10 ≦ j ≦ 40, h + i + j = 100. Fe is for obtaining a large saturation magnetic flux density Bs, and M is for forming an oxide in the amorphous phase to increase the specific resistance ρ. h,
When i and j are within the above ranges, a soft magnetic alloy having a large saturation magnetic flux density Bs, a specific resistance ρ, and a high magnetic permeability μ can be obtained,
When h, i, and j are out of the above ranges, the soft magnetic characteristics deteriorate.

In the above composition, when the element M is one or more elements selected from rare earth elements, h and j are at% and 50 ≦ h ≦ 70 and 10 ≦ j ≦ 3.
More preferably, it is 0.

The composition formula consists microcrystalline soft magnetic alloy represented by _{(Co 1-c T c)} x M y X z O w, element T, Fe,
Ni is an element containing one or both of Ni, and the element M is Ti, Zr, Hf, V, Nb, Ta, C
r, Mo, Si, P, C, W, B, Al, Ga, Ge and one or more elements selected from rare earth elements, and X is Au, Ag, Cu, Ru, Rh, Os , I
one or more elements selected from r, Pt, and Pd, and the composition ratio is such that c is 0 ≦ c ≦ 0.7, x, y,
z and w are atomic%, 3 ≦ y ≦ 30, 0 ≦ z ≦ 20, 7 ≦
Those satisfying the relationship of w ≦ 40 and 20 ≦ y + z + w ≦ 60, with the balance being x.

In the soft magnetic alloy, an amorphous phase containing a large amount of an oxide of the element M is mixed with a microcrystalline phase mainly composed of Co and the element T. It is more preferable to have a structure including the same.

The composition formula consists amorphous soft magnetic alloy mainly composed of amorphous structure represented by _{Co a Zr b Nb c, a} , b, c in at%, 78 ≦ a ≦ 91,0 . 5 ≦
Those satisfying the relationship of b / c ≦ 0.8. Saturation magnetic flux density B
s depends on the concentration of Co, and in order to increase Bs,
It is necessary to satisfy 78 ≦ a ≦ 91. If a> 91,
It is not preferable because the corrosion resistance is lowered and an amorphous structure is hardly formed, and crystallization starts. Also, a <7
A value of 8 is not preferred because the ratio of adjacent Cos decreases and the magnetic coupling is cut off, which makes it difficult to exhibit soft magnetic characteristics. The magnetic permeability μ also shows a high value in the range of 78 ≦ a ≦ 91, depending on the Co concentration.

[0025] The composition _{formula, T 100-defg X d M} e Z f Q g
Where bcc-Fe, bcc-FeCo, bcc-
It is made of a microcrystalline soft magnetic alloy mainly composed of one or more crystal grains of Co, and the element T is an element containing one or both of Fe and Co, and the element X is S
i is an element containing one or both of Al, and the element M is Ti, Zr, Hf, V, Nb, Ta,
One or more elements selected from Mo and W, the element Z is an element containing one or both of C and N, and Q is Cr, Re, Ru, Rh, N
One or more elements selected from i, Pd, Pt, and Au, and d, e, f, and g are at%. 0 ≦ d ≦ 2
5, 1 ≦ e ≦ 10, 0.5 ≦ f ≦ 15, 0 ≦ g ≦ 10. When d, e, f, and g are within the above ranges, a soft magnetic alloy having a large magnetic permeability μ, a low coercive force Hc, and a small magnetostriction constant λ can be obtained.

The composition formula is T _100-pqefg Si _p Al _q
Represented by _{M e Z f Q g, bcc} -Fe, bcc-FeC
o, a microcrystalline soft magnetic alloy mainly composed of one or more crystal grains of bcc-Co, and the element T is Fe, C
an element containing one or both of o,
The element M is Ti, Zr, Hf, V, Nb, Ta, Mo,
W is one or more elements selected from W, the element Z is an element containing one or both of C and N, and Q is Cr, Re, Ru, Rh, Ni, P
one or more elements selected from d, Pt, and Au, where p, q, e, f, and g are at% and 8 ≦ p ≦ 1
5, 0 ≦ q ≦ 10, 1 ≦ e ≦ 10, 0.5 ≦ f ≦ 15,
Those satisfying the relationship of 0 ≦ g ≦ 10. p, q, e, f,
If g is within the above range, the magnetic permeability μ is large and the coercive force H
A soft magnetic alloy having a low c and a small magnetostriction constant λ can be obtained.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The magnetoimpedance effect used in an embodiment of the present invention will be described. When a minute high-frequency current is applied to a soft magnetic material formed in a wire shape or a ribbon shape, an output voltage due to impedance is generated at both ends of the soft magnetic material. The magneto-impedance effect is an effect in which when an external magnetic field is applied to a soft magnetic material to which a minute high-frequency current has been applied, the impedance of the soft magnetic material changes sensitively, and the output voltage across the soft magnetic material changes.

The change in impedance of the soft magnetic material due to the application of an external magnetic field is caused by the "skin effect" in which an alternating current flows near the surface of the magnetic material when the alternating current is applied to the magnetic material. It is known to be.

More specifically, the magneto-impedance effect means that in a closed circuit shown in FIG. 6, an alternating current Iac in the MHz band is applied from a power source Eac to a thin-film, wire-like, or ribbon-like magnetic substance Mi. In the state, the magnetic substance Mi
When an external magnetic field Hex is applied in the length direction of the magnetic material M
Output voltage Em due to material-specific impedance across i
i occurs, and the amplitude of the output voltage Emi changes within a range of several tens of percent corresponding to the intensity of the external magnetic field Hex, that is, a phenomenon that causes impedance change.

Since the element having the magneto-impedance effect is excited in the outer circumferential direction of the element, there is no demagnetizing field and the direction of the element of the magnetization vector, that is, the AC current Iac
Since the magnetic permeability changes abruptly with a slight rotation in the flow direction, the demagnetizing field in the longitudinal direction is also small, and the length of the element is 1 m.
Even if it is about m, the magnetic field detection sensitivity hardly deteriorates.

Further, the magneto-impedance effect element has
The characteristic that a weak magnetic field sensor having a high resolution of about 0 ^-5 Oe can be obtained, and excitation of several MHz or more is possible, so that high-frequency excitation of several hundred MHz can be used freely as a carrier for amplitude modulation. When used as
It has the characteristic that it is easy to set the cutoff frequency to 10 MHz or higher, and the characteristic that the power consumption can be set to 10 mW or less.

As a soft magnetic material exhibiting a magnetic impedance effect, an Fe—Co—Si—B-based material such as (Fe ₆ C)
o _{94) 72.5} amorphous wire (Mori KeiToshio other "magnetic impedance (MI) element" of the Si _12.5 B _15, the Institute of Electrical Engineers of Japan Magnetics Society article Vol.1, MAG-94, N
o. 75-84, pages 27-36, published in 1994).

The magnetic properties of the Fe—Co—Si—B material
The impedance characteristic is, as shown in FIG. 4, the output voltage Emi with respect to the applied positive / negative external magnetic field Hex (Oe).
(MV) shows the characteristic of a substantially left-right symmetrical shape around the external magnetic field Hex = 0 (Oe). In the measurement of the magnetic impedance characteristics shown in FIG. 4, a driving AC signal having a frequency of 3 MHz is applied to the wire-shaped magneto-impedance effect element, and the magnitude of the external magnetic field is changed in a range of -5 (Oe) to 5 (Oe). The test was performed under the following conditions.

Conventionally, the magneto-impedance effect element has been used for applications such as an azimuth sensor for sensing terrestrial magnetism and a rotary encoder which is a rotation angle sensor of a spindle motor of a hard disk or floppy disk drive. According to the present invention, a magneto-impedance effect element is used in an antenna section of a receiving device.

FIG. 1 is a block diagram showing an embodiment of the receiving apparatus of the present invention. The antenna section 11 includes a magneto-impedance effect element 11b that captures a radio signal, a drive circuit 11a that supplies a drive AC signal to the magneto-impedance effect element 11b, a rectifier circuit 11c that rectifies a mixed signal of the drive AC signal and the received radio signal, It comprises a frequency discriminator 11d for removing the drive AC signal.

The shape of the magneto-impedance effect element 11b is a wire shape, a ribbon shape, or the like. The wire-shaped or ribbon-shaped magneto-impedance effect element can be manufactured by a single roll method, a casting method, or a fluid cooling method. Also,
You may use the thin film-shaped magneto-impedance effect element 11b manufactured by the sputtering method or the vapor deposition method.

The magneto-impedance effect element 11b
Are formed at both ends with electrodes for connection to the drive circuit 11a, and are formed such that the direction in which the drive AC signal flows is the hard magnetization axis. Therefore, the magnetic permeability increases in the direction in which the drive AC signal flows, and the detection sensitivity to the received radio signal increases.

As a method of setting the direction in which the drive AC signal of the magneto-impedance effect element 11b flows as the hard magnetization axis,
After the magneto-impedance effect element 11b is formed by a method such as a sputtering method in a magnetic field, or by a single roll method, a casting method, a fluid cooling method, a sputtering method, or a vapor deposition method in the absence of (or small) magnetic field. There is a method of placing in a magnetic field in a high temperature atmosphere and annealing in a magnetic field.

The magneto-impedance effect element 11b can be formed with a length of 0.1 to 10 mm and a thickness of 1 to 50 μm. If the length and thickness of the magneto-impedance element are different, the magneto-impedance effect of the magneto-impedance element will also be different, so the appropriate size of the magneto-impedance element according to the sensitivity required by the receiver and the application of the receiver It is better to use

Composition of magneto-impedance effect element 11b
Is, for example, (Co_0.94Fe_0.06) _72.5Si_12.5B₁₅so
is there. Soft magnetism of Fe-Co-Si-B system other than this composition
Materials and Co-T-M-X-O-based materials (element T is Fe, N
element containing one or both of i,
Element M is Ti, Zr, Hf, V, Nb, Ta, Cr,
Mo, Si, P, C, W, B, Al, Ga, Ge and rare earth
One or more elements selected from the group consisting of
X is Au, Ag, Cu, Ru, Rh, Os, Ir, P
one or more elements selected from t and Pd),
Co-Ta-Hf system, Fe-MO system (M is Ti, Z
selected from r, Hf, V, Nb, Ta, W and rare earth elements
One or more elements), Co-Zr-Nb
System, T-Si-Al-MZQ system (element T is Fe,
Element containing one or both of Co
The element M is Ti, Zr, Hf, V, Nb, Ta, M
one or more elements selected from o and W;
The element Z contains one or both of C and N.
Q is Cr, Re, Ru, Rh, Ni,
One or more elements selected from Pd, Pt, and Au
Using a soft magnetic material such as
The result element 11b may be formed.

The magnitudes of the current and the voltage of the drive AC signal supplied to the magneto-impedance effect element 11b by the drive circuit 11a are, for example, 10 mA and 2V. Also, the driving circuit 1
If the circuit 1a is a self-oscillation circuit, the magneto-impedance effect element 11b and the drive circuit 11a can be integrated, so that instability of sensitivity due to floating impedance of the circuit can be prevented.

FIG. 2 shows a stabilized Colwitz oscillation circuit as an example of a self-oscillation type driving circuit. AM broadcasting is 5
The carrier wave in the frequency band of 00 kHz to 2000 kHz is amplitude-modulated by an audio signal such as voice or music and transmitted. The receiving device of the present invention detects a change in a magnetic field component of a radio signal and converts it into an electric signal.

A drive circuit 11a supplies a drive AC signal to the wire-shaped or ribbon-shaped magneto-impedance element 11b, and an output voltage is generated at both ends of the magneto-impedance element 11b by impedance. The frequency of the driving AC signal is preferably set to 10 times to 20 times or more of the frequency of the carrier wave of the AM broadcast. In the present embodiment, the frequency is 20 MHz. When the AM radio wave signal reaches the receiver, the amplitude of the output voltage across the magneto-impedance effect element 11b changes according to the change in the amplitude of the magnetic component of the radio wave signal.

FIG. 3 shows the magneto-impedance effect element 11.
The figure shows how the output voltage at both ends of b changes according to the received radio signal. The carrier wave 32 of the AM wave is amplitude-modulated by the audio signal 31. The amplitude of the output voltage at both ends of the magneto-impedance effect element 11b is
2, the output from both ends of the magneto-impedance effect element 11 b is
And a drive AC signal 33.

The magnetic-impedance characteristics of the Fe—Co—Si—B-based material shown in FIG. 4 indicate that the output voltage with respect to the applied positive or negative external magnetic field is substantially bilaterally symmetric about the external magnetic field Hex = 0. Is shown. Therefore, the amplitude of the output voltage is the same whether the carrier 32 is positive or negative. However, the carrier wave 32 is rectified in the demodulation stage, and the negative part of the carrier wave 32 is removed or converted to be positive at the time of rectification. Therefore, the sign of the carrier wave 32 is converted without distinction by the magneto-impedance effect element 11b. Even so, the audio signal is correctly demodulated.

When an Fe—Co—Si—B-based material is used for the magneto-impedance effect element 11b, 0.5 to 0.5%
By applying a bias magnetic field of 1 (Oe), the curve of the magnetic impedance characteristic shown in FIG. 4 is shifted in the horizontal direction (axial direction of the magnetic field) to change the output voltage when the magnetic field is near 0 (Oe). May be increased. By applying the bias in this manner, the change in the output voltage across the magneto-impedance effect element 11b corresponding to the change in the magnetic field component of the broadcast radio wave becomes agile.

As a method of applying a bias magnetic field to the magneto-impedance effect element, for example, as shown in FIG.
There is a method in which a coil C is wound around the magneto-impedance effect element 11b by an appropriate number of turns and a bias magnetic field is generated by flowing a DC current through the coil C.

A mixed signal of the received radio wave signal of the carrier wave 32 and the driving AC signal 33 output from both ends of the magneto-impedance effect element 11b is input to the rectifier circuit 11c.
In the present embodiment, the diodes 11e, 11e, 11
Since the rectifier circuit is constituted by the bridge circuit composed of e and 11e, the negative portion of the mixed signal is converted to positive. The rectifier circuit 11c is not limited to a bridge circuit of a diode, and may be any circuit having a rectifying function. For example, one diode may be connected between the magneto-impedance effect element 11b and the frequency discriminator 11d. The mixed signal of the received radio wave signal of the carrier wave 32 and the driving AC signal 33 is rectified,
1d, and the drive AC signal 33 is removed.

When the frequency of the driving AC signal is set higher than the frequency of the received radio signal, the frequency discriminator 1
1d is constituted by a low-pass filter. Conversely, when the frequency of the driving AC signal is set lower than the frequency of the received radio signal, the frequency discriminator 11d is configured by a high-pass filter. However, the frequency of the driving AC signal is preferably higher than the frequency of the carrier of the received radio signal.

The magneto-impedance effect element 11b does not exhibit the magneto-impedance effect unless the driving AC signal has a high frequency. The frequency of the drive AC signal is at least several hundreds of kHz.
z is necessary, but if the frequency of the driving AC signal is close to the frequency of the carrier of the received radio signal, the frequency discriminator 11d
It becomes difficult to remove the driving AC signal from the mixed signal of the reception radio signal and the driving AC signal.

Although the frequency of the medium wave broadcast is in a band higher than 500 kHz, if the driving AC signal is to be made lower than this, the difference between the frequency of the driving AC signal and the frequency of the received radio wave signal can be at most several hundred kHz, and the high-pass filter is not used. This makes it difficult to remove the driving AC signal. On the other hand, in order to increase the frequency of the driving AC signal higher than the frequency of the carrier of the received radio signal, the driving AC signal can be as high as the low-pass filter for removing the driving AC signal allows. In practice, the frequency of the driving AC signal may be several tens times the frequency of the received radio signal.

In this embodiment, the frequency discriminator 11d
Is constituted by a low-pass filter including a capacitor 11f and a resistor 11g. Condenser 11h
Is for removing the DC component mixed in the mixed signal of the received radio signal and the driving AC signal.

The frequency discriminator is not limited to the one shown in the present embodiment, but may be any one which can remove a driving AC signal. For example,
Instead of the high-pass filter and the low-pass filter, a band-pass filter that passes only the carrier of the received radio signal or a band-eliminate filter that does not pass the driving AC signal may be used. Further, bias may be applied instead of using a filter constituted by a capacitor or a resistor.
Applying a bias and removing the drive AC signal increases sensitivity.

After the driving AC signal 33 is removed from the mixed signal of the receiving radio signal of the carrier wave 32 and the driving AC signal 33, the extracted receiving radio signal is sent to the high-frequency amplifier circuit 12.
Is amplified by

Incidentally, the antenna section 11 does not have a function of selecting the frequency of the carrier of the received radio signal. That is, the input and output of the high frequency amplifier circuit 12 are mixed with radio signals of all received frequencies. The tuning circuit 13 provided at the subsequent stage selects a signal of a target frequency from the output of the high frequency amplifier circuit 12, and the detection circuit 14 extracts an audio frequency signal from a mixed signal of the audio frequency signal and the carrier. It is.

The tuning circuit 13 and the detection circuit 14 are configured using circuits used in a general AM broadcast receiver. For example, tuning is performed by a resonance circuit including a coil and a capacitor or a band-pass filter, and a carrier is removed by a low-pass filter to extract an audio signal. The extracted audio signal is amplified by the low-frequency amplifier circuit 15 as necessary, and
6 makes it possible to listen as voice or music.

[0057]

According to the receiving apparatus of the present invention described in detail above, the antenna section is formed by using a magneto-impedance effect element instead of using a conventional ferrite core winding coil. Thereby, remarkable miniaturization can be realized.

Further, the direction in which the drive AC signal flows in the magneto-impedance effect element is defined as the hard axis, and the bias sensitivity is applied in the direction in which the drive AC signal flows to improve the receiving sensitivity of the receiver. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a receiving device of the present invention.

FIG. 2 is a circuit diagram showing an example of a driving circuit of the present invention.

3 is a graph showing how an output voltage of a magneto-impedance effect element of the receiving device of FIG. 1 changes according to a received radio signal.

FIG. 4 is a graph showing a magnetic impedance characteristic of a Fe—Co—Si—B based magnetic impedance effect element.

FIG. 5 is a conceptual diagram showing a method of applying a bias magnetic field to a magneto-impedance effect element.

FIG. 6 is a conceptual diagram showing a method of applying a drive AC signal to a magneto-impedance effect element and applying an external magnetic field.

FIG. 7 is a block diagram showing a conventional receiving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Antenna part 11a Drive circuit 11b Magnetic impedance effect element 11c Rectifier circuit 11d Frequency discriminator 12 High frequency amplifier circuit 13 Tuning circuit 14 Detection circuit 15 Low frequency amplifier circuit 16 Speaker

Claims (12)

[Claims] 1. A receiving apparatus comprising an antenna unit, a tuning circuit, and a detection circuit, wherein the antenna unit includes a magneto-impedance effect element, a driving circuit that supplies a driving AC signal to the magneto-impedance effect element, and a receiving circuit. A receiving apparatus comprising: a rectifier circuit for rectifying a mixed signal of a radio signal and a driving AC signal supplied from the driving circuit; and a frequency discriminator for separating and extracting a received radio signal from the mixed signal. 2. The receiving device according to claim 1, wherein the magneto-impedance effect element has electrodes formed at both ends for connection to the drive circuit, and a direction in which the drive AC signal flows is a hard magnetization axis. 3. The magneto-impedance effect element includes:
The receiving device according to claim 1, wherein a bias magnetic field is applied in a direction in which the drive AC signal flows. 4. The receiving device according to claim 1, wherein said magneto-impedance effect element is formed in a ribbon shape or a wire shape. 5. The frequency of the driving AC signal is higher than the frequency of a carrier of a received radio signal.
The receiving device according to any one of the above. Wherein said magneto-impedance effect element is made of amorphous soft magnetic alloy having a composition formula represented by _{(Fe 1-a Co a)} 100-xy (Si 1-b B b) x M y, M Is an element containing one or both of Cr and Ru, and a and b representing composition ratios are 0.05 ≦ a ≦ 0.1, 0.2 ≦ b
≦ 0.8, and x and y are at% and 10 ≦ x ≦ 35, 0
The receiving device according to claim 1, wherein a relationship of ≦ y ≦ 7 is satisfied. Wherein said magneto-impedance effect element, represented by a compositional formula of Co _l Ta _m Hf _n, consists amorphous soft magnetic alloy in which the amorphous structure mainly, l, m, n is a
At t%, 70 ≦ l ≦ 90, 5 ≦ m ≦ 21, 6.6 ≦ n ≦
The receiving device according to any one of claims 1 to 5, wherein a relationship of 1 and 1 ≦ m / n ≦ 2.5 is satisfied. 8. The magneto-impedance effect element has a composition formula of Fe _h M _i O _j and is made of a microcrystalline soft magnetic alloy having an amorphous structure as a main component, and M represents Ti, Zr,
1 selected from Hf, V, Nb, Ta, W and rare earth elements
Species or two or more elements, where h, i, and j are at%
Where 45 ≦ h ≦ 70, 5 ≦ i ≦ 30, 10 ≦ j ≦ 40,
The receiving device according to claim 1, wherein a relationship of h + i + j = 100 is satisfied. Wherein said magneto-impedance effect element is made of a microcrystalline soft magnetic alloy whose composition formula is represented by _{(Co 1-c T c)} x M y X z O w, element T, Fe, and Ni The element M includes one or both of them, and the element M includes Ti,
Zr, Hf, V, Nb, Ta, Cr, Mo, Si, P,
One or more elements selected from C, W, B, Al, Ga, Ge and rare earth elements, and X is Au, A
g, one or two or more elements selected from Cu, Ru, Rh, Os, Ir, Pt, and Pd.
c is 0 ≦ c ≦ 0.7, x, y, z and w are atomic% and 3
≦ y ≦ 30, 0 ≦ z ≦ 20, 7 ≦ w ≦ 40, 20 ≦ y +
2. The relationship of z + w ≦ 60 is satisfied, and the balance is x.
The receiving device according to claim 5. 10. The magneto-impedance effect element,
Composition formula consists amorphous soft magnetic alloy mainly composed of amorphous structure represented by _{Co a Zr b Nb c, a} , b, c in at%, 78 ≦ a ≦ 91,0.5 ≦ b / The receiving device according to claim 1, wherein a relationship of c ≦ 0.8 is satisfied. 11. The magnetic impedance effect element,
Represented by a compositional formula of _{T 100-de- fg X d M} e Z f Q g, bcc
-A microcrystalline soft magnetic alloy mainly composed of one or more crystal grains of Fe, bcc-FeCo, and bcc-Co, and the element T is an element containing one or both of Fe and Co. The element X is an element containing one or both of Si and Al, and the element M is
One or more elements selected from Ti, Zr, Hf, V, Nb, Ta, Mo, and W;
Element containing one or both of N,
Q is Cr, Re, Ru, Rh, Ni, Pd, Pt, A
one or more elements selected from u, d,
e, f, and g are at%, 0 ≦ d ≦ 25, 1 ≦ e ≦ 10,
The receiving device according to claim 1, wherein a relationship of 0.5 ≦ f ≦ 15 and 0 ≦ g ≦ 10 is satisfied. 12. The magneto-impedance effect element,
Represented by a compositional formula of _{T 100-pq- efg Si p Al} q M e Z f Q g, bcc-Fe, bcc-FeCo, microcrystalline mainly containing one or more of crystal grains of the bcc-Co Made of a soft magnetic alloy, the element T is an element containing one or both of Fe and Co, and the element M is Ti, Z
r, Hf, V, Nb, Ta, Mo, W are one or more elements selected from the group consisting of C and N; C
one or more elements selected from the group consisting of r, Re, Ru, Rh, Ni, Pd, Pt, and Au;
f and g are at%, 8 ≦ p ≦ 15, 0 ≦ p ≦ 10, 1 ≦
The receiving device according to claim 1, wherein a relationship of e ≦ 10, 0.5 ≦ f ≦ 15, and 0 ≦ g ≦ 10 is satisfied.