JP2581027B2 - Antenna circuit and wrist-mounted radio - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small portable radio, and more particularly to an antenna circuit and an arm-mounted radio using the same.

[0002]

2. Description of the Related Art Heretofore, there has been a problem that the antenna resonance circuit is displaced between when the arm is worn and when the arm is not worn due to the influence of the human body.

[0003]

The present invention is applied to an antenna circuit having a loop antenna integrated with an arm band to be worn on an arm, and to an arm-mounted radio.

That is, since the loop antenna is mounted around the arm, the length of the loop antenna differs depending on the individual who uses the loop antenna. Then, since the value of the inductance of the loop antenna differs from individual to individual, the resonance frequency of the antenna circuit varies depending on the individual, and the gain of the loop antenna varies. This affects the sensitivity of each person's wireless device, and remarkably, if the resonance frequency shifts, transmission and reception may not be possible.

On the other hand, when the loop antenna is worn on the arm, the resonance frequency shifts due to the influence of the human body. This also can send and receive in a state not mounted on the arm, and attached to the arms, is that there may not be able to send and receive.

Since these are phenomena caused by the shift of the resonance frequency of the antenna circuit, it is sufficient to return the resonance frequency to the original one. However, it is very difficult for the loop antenna user to perform this manually. Annoying and unrealistic.

Accordingly, an object of the present invention is to provide an antenna circuit capable of automatically correcting the deviation of the resonance frequency of the antenna circuit and always maintaining the resonance frequency at a constant frequency.

Further, the wrist-worn radio device of the present invention equipped with such an antenna circuit always has a constant sensitivity irrespective of the thickness of the wrist of the individual to be used, irrespective of whether the wrist is worn or not. Can be sent and received.

[0009]

In order to solve the above-mentioned problems, an antenna circuit according to the present invention includes a loop antenna integrated with an arm band to be worn on an arm, and a first antenna connected to the loop antenna. and a variable capacitance diode is configured to resonate for a particular frequency, the
The loop antenna has a variable length, and a second variable capacitance diode connected to the antenna circuit, and for changing the capacitance of the second variable capacitance diode at any time according to the length of the loop antenna, A voltage generation circuit for generating a control voltage to be applied to the second variable capacitance diode, wherein the antenna is controlled in accordance with the length of the loop antenna.
It is characterized in that the deviation of the resonance frequency of the power supply circuit is automatically corrected .

[0010] Also, the wrist-mounted radio of the present invention comprises a loop antenna provided on the wristband, band coupling means for detachably attaching the wristband to the wrist, and a variable capacitor forming a resonance circuit with the loop antenna. and a diode, the capacitance value of the variable capacitance diodes have a control means for controlling to vary the predetermined value in the arm during mounting and the arm is not mounted in the loop antenna, the arm is installed and the arm of the loop antenna Undressed
The deviation of the resonance frequency of the resonance circuit between when
And correcting the.

Further, the loop antenna comprises a first antenna provided in a first arm band and a second antenna provided in a second arm band. I do.

[0012] Further, the band coupling means may include the first
It has a detecting means for detecting whether or not the antenna body and the second antenna body are electrically coupled, and the control means is controlled by the detecting means.

[0013]

As described above, the object of the present invention is to automatically change the resonance frequency caused by the change in the inductance value of the loop antenna depending on the thickness of the arm and whether the arm is worn or not. To be corrected. As a means for this, an electric coupling capacitance is included in a connector attached to the loop antenna, or a variable capacitance diode is connected, and these electric coupling capacitances are automatically changed.
Generally, as the length of the loop antenna increases, the inductance increases, so that the electrical coupling capacitance is reduced. vice versa,
As the loop antenna becomes shorter, the inductance decreases, so that the electric coupling capacity is increased. With such a change, the resonance frequency can be kept constant.

When the inductance changes between when the arm is worn and when the arm is not worn, if a DC voltage change corresponding to the inductance is applied from the voltage generator to the variable capacitance diode, the electrical coupling capacitance automatically changes. Can be
The resonance frequency can be kept constant.

[0015]

FIG. 1 shows an embodiment of the present invention in which an antenna circuit for providing electrical coupling capacitance to a connector portion of a loop antenna is applied to a wristwatch band and a connector. The arm bands 101 and 102 are made of an insulating material such as synthetic leather, and are connected to each other by a buckle 103. In the buckle 103,
A metal plate 105 is attached. Metal plate 105 is buckle 1
At the center of the buckle 103, it is attached so as to cross the arm band 102, and as shown in the figure, has a sufficiently large area as compared to the area of the buckle 103 viewed from the surface. Also, a metal plate 105
Is connected from the back to a loop antenna 106 contained inside the arm band 101. Loop antenna l
04 and 106 are made of a conductor such as copper.

The width of the loop antenna 104 inside the wristband 102 becomes narrower toward the end of the wristband 102. In the case of a person with a thin arm, the surplus portion of the arm band 102 is increased.

That is, although the arm orbital length of the arm bands 101 and 102 becomes short, the metal plate 105 and the loop antenna 104
The overlapping area increases. An electric coupling capacity is generated in the overlapping portion, and the electric coupling capacity in this case becomes large.

Conversely, in the case of a person with a thick arm, the arm band 102
The remainder is reduced. That is, the arm band 101,
Although the arm orbital length of 102 is long, the overlapping area of the metal plate 105 and the loop antenna 104 is small.

In this case, the electric coupling capacity becomes small.

The loop antenna 1 included in the arm band
Reference numeral 04 does not function as an antenna at the tip of the metal plate 105. Therefore, the meaning that the loop antenna is long means that the position of the metal plate 105
The tip of 04 indicates that the opposite side is long.

FIG. 2 is an electrical equivalent circuit of the structure of FIG. The loop antennas 104 and 106 are represented by coils and have inductances 104a and 106a. Also,
There is an electric coupling capacitance 107a formed by overlapping the metal plate 105 and the loop antenna 104, and another electric coupling capacitance 108a forming a resonance circuit.

The electric coupling capacitance 108a is a fixed capacitance or a combination of a variable capacitance diode and a fixed capacitance.
Variable capacitance is conceivable. Both terminals 10 of this capacitor 108a
A high-frequency signal is extracted using 9a, 10b, or one of them.

By keeping the product of the sum of the inductances 104a and 106a and the reciprocal of the sum of the reciprocals of the electrical coupling capacitors 107a and 108a constant, the same resonance frequency can always be maintained.

[0024] These are expressed by the equation, the inductance L04a, 106a to _{L 104a,} L l06a, electrically coupling capacitance 107a, L08a the _C l07a, C _108a, if the resonance frequency f,

[0025]

(Equation 1)

The following relationship holds. To make f a constant value,

[0027]

(Equation 2)

It suffices if

While maintaining the relationship of Equation 3, the loop antenna 1
The value of the electrical coupling capacitance 107a is calculated theoretically to compensate for the change in the inductances 104a and 106a when the lengths of the coils 04 and 106 are slightly shortened.

The inductances 104a and 106a are connected at a high frequency by the buckle 103 and become one inductance.

Assuming that the value of this inductance is L _total ,

[0032]

(Equation 3)

## EQU1 ##

Here, K is the Nagaoka coefficient, μο is the magnetic permeability in vacuum, and S is the loop antenna 104, 106 with the buckle 1
The open area after the connection at 03, N is the number of turns of the loop antenna, and the horizontal width of the loop antenna.

The aperture area S formed by the loop antenna is
If the opening is circular and the radius is a, then S = πα ² (Equation 5). Now, assuming that the length of the loop antenna is slightly shortened, if the shortened amount is set as Δα, the opening area S ′ at this time is

[0036]

(Equation 4)

By substituting equation (6) into equation (4), L _total when the length of the loop antenna is shortened can be obtained.

L before and after the loop antenna is shortened
The ratio of the _total value is proportional to the ratio of the open area S, and the ratio ΔL
_total is

[0039]

(Equation 5)

According to equation (7), when Δα increases,
ΔL _total becomes smaller than 1 and Δα = 0, that is,
It can be seen that the value of L _total is smaller than when the length of the loop antenna is not changed.

Next, the electrical coupling capacitance 107a is determined.

[0042]

(Equation 6)

Σ is the dielectric constant of the substance, A is the area of the portion where the loop antenna 104 overlaps the metal plate 105, d
Is the distance between the two metal surfaces. Σ is determined from the material of the arm band 102 covering the loop antenna 104 and the dielectric constant of the minute space between the back surface of the arm band 102 and the metal plate 105.

Here, _assuming that C _l08a >> C _l07a , FIG.
Coupling capacitance affecting resonance frequency of resonant circuit
Can be approximated by _C107a . Therefore,

[0045]

(Equation 7)

As shown in Equations 3 and 4, L _total and C
The product of _total must be constant. Therefore, when the length of the loop antenna obtained by equation (7) is reduced, ΔL
The value of the _total may do it to compensate the ratio △ C _total change in C _total. By transforming Equation 3 and expressing this meaning by an equation,

[0047]

(Equation 8)

Is as follows. Formula 8, 9 expression, the value of △ C _total, is replaced with the amount of change in the area A of the electrical coupling capacitance _C l07a. Therefore, considering the area A as a function of △ α,

[0049]

(Equation 9)

Is as follows. β is the area when △ α = 0. When _Δα increases, that is, when the length of the loop antenna decreases, the value of A ( _Δα ) increases, and the value of C _107a increases. Therefore, the ratio of the change of L _total △ L
_Total can be compensated. FIG. 3 is a diagram expressing the expression l3. ΔL _total can be compensated by changing A (△ α) within a range of Δα and 2πa. The loop antenna 104 shown in FIG. 1 has a width that is narrower toward the tip, but the width is such that the area where the loop antenna 104 and the metal plate 105 overlap is 1
What is necessary is just to decide to follow Formula 3.

On the other hand, when C _108a >> C _107a does not hold, it is necessary to consider the value of C _{108a in} C _total , but even in that case, C _108a is not included in the expression of A (△ α). but it is, obtained in theoretical calculation, thus the function may be determined the width of the loop antenna 104.

As described above, when the length of the loop antenna changes by △ α, A (△ α) is automatically determined, and the compensated electrical coupling capacitance C _107a is determined.

The C _107a determined in this way forms a resonance circuit together with Ltotal when the length of the loop antenna is shortened, and the resonance frequency is determined before the length of the loop antenna is shortened. It does not change compared to. Thus, the object of the present invention is achieved.

That is, in the case of a person with a thin arm, the loop antenna 1 included in the arm bands 101 and 102 circling the arm.
The circuit lengths of the loops 04 and 106 become shorter and their inductances 104a and 106a become smaller, but the area of the metal plate 105 and the loop antenna 104 becomes larger and their capacitance 107a becomes larger. Inductance 10
4a and 106a are compensated for by the capacitance 107a.
There, inductance 104a, 106a and the capacitance 107a, the product of the reciprocal of the sum of the reciprocal of 108a becomes constant.

Also, a person with a thick arm can use the loop antenna 10
4,106 has a longer circuit length, and its inductance 1
04a and 106a become large, but the capacitance 10
7a becomes smaller. Inductance 104a, 106a
Is offset by the capacitance l07a.
Inductance 104a, 106a and capacitance l
The product of the reciprocal of the sum of the reciprocals of 07a and l08a is constant.

FIG. 4 is a side view of the buckle portion of FIG. Since the arm band 102 is merely inserted between the buckle 103 and the metal plate 105, attachment and detachment is easy. Also, the buckle 103 presses the arm band 102 at two places, so that it does not easily come off even if the arm band 102 is pulled from both sides.

FIG. 5 is a cross-sectional view of an arm band using the same antenna circuit as in FIG. A loop antenna 112 is included inside the arm band 111. A large number of hairs 113 for connecting both arm bands are provided. By the bristle 113, both arm bands can be overlapped and connected at an arbitrary position. And
When overlapping, if the loop length of the arm band 111 is shortened, the overlapping area of the loop antennas 11 and 12 becomes large, and the portion has a large capacitance. On the other hand, when the orbital length of the arm band 11l is increased, the loop antenna 11l is increased.
Since the overlapping area of the two becomes smaller, the capacitance of that part becomes smaller.

FIG. 6 is a view of the embodiment of FIG. 5 viewed obliquely from above. Also in this case, the electrical equivalent circuit is the same as FIG. 2, and if the length of the loop antenna 112 changes, the overlapping area of the loop antenna 112 automatically changes,
Since the electric coupling capacitance l07a changes, the resonance frequency can always be kept at a constant value.

The narrow portion of the loop antenna 112 may be determined so as to satisfy the expression (13).

FIG. 7 shows an example in which the present invention is applied to a wristwatch type radio. The main body 114 includes a wireless device. This style, which is very simple and does not feel like a radio,
It is suitable for simple transceivers and selective call receivers.

FIG. 8 shows an antenna circuit diagram of the present invention in which a variable capacitance diode is attached to a conventional antenna circuit.
This is one embodiment .

FIG. 9 is an example of an antenna circuit conventionally used. The embodiment shown in FIG. 8 also shows an embodiment that suppresses a change in resonance frequency due to a change in the length of the loop antenna.

The loop antenna 201 is connected to the connector 202
Can be attached and detached, and electrically,
By connecting the connector 202, the loop antenna 20
1 and the loop antenna 201 and the variable resistor 204.
Will be connected. The variable resistor 204 determines the DC voltage of the variable capacitance diode 206 together with the resistor 203. A power supply voltage is supplied from a terminal 212. This power supply is a power supply that always generates a constant voltage. Then, the loop antenna 201 is connected to the ground 2l.
1 grounded. Therefore, the variable capacitance diode 20 is determined by the resistance ratio between the resistor 203 and the variable resistor 204.
The voltage applied to 6 is determined. Further, the variable resistor 204
Is changed, the voltage applied to the variable capacitance diode 206 changes, and the capacitance can be changed. Since the resistance value of the variable resistor 204 is as large as several tens to hundreds of kΩ, Q as a resonance circuit of the antenna circuit including the loop antenna 201 cannot be reduced, and the sensitivity of the antenna circuit does not decrease.

The capacitors 205 , 207 and 210 are for DC cutoff .

The variable-capacitance diode 208 is originally used for tuning. From the terminal 214, a DC voltage for tuning is
9. Conventionally, as shown in FIG. 9, an antenna circuit is configured by the variable capacitance diode 208, the capacitor 207, and the loop antenna 201. This variable capacitance diode 208 can eliminate the dispersion of the resonance frequency of the antenna circuit when the antenna circuit always resonates at the same frequency, or can be replaced with a simple capacitor if there is no variation. It is.

The purpose of the present invention is to automatically compensate for the deviation of the resonance frequency when the length of the loop antenna is changed. There is a great feature in that the capacitance diode 206 is added.

FIG. 10 is a diagram showing the resonance characteristics of the antenna circuit when the length of the loop antenna 201 is long using the conventionally used antenna circuit as shown in FIG.
FIG. 11 is a diagram showing resonance characteristics when the length of the loop antenna 201 is short.

When the length of the loop antenna 201 is long,
Inductance of the loop antenna 20l is receiving the transmission station of a low frequency f ₁ to become large. Therefore, if you reduce the length of the loop antenna 201, that the inductance becomes smaller, sensitivity of the transmission station f ₁ which has been received until now is decreased, there is a higher frequency instead f ₂
The sensitivity of the transmitting station increases. That is, the tuning deviation occurred because the length of the loop antenna 201 was changed.

According to the antenna circuit of the present invention, it is possible to prevent a tuning deviation caused by such a cause.

[0070] In FIG. 1, the inductance by the amount of shortening the loop antenna 201 is reduced, in order to keep the coming maximum sensitivity to frequencies f _1, increases the capacitance of the variable capacitance diode 206. Variable capacitance diode 20
In order to increase the capacity of 6, the DC voltage applied to the cathode side is reduced. To reduce the DC voltage, the variable resistor 204 may be reduced. The variable resistor 204, FIG.
As shown in FIG. 12, it is composed of a connector 202 and a resistance plate 221 formed inside the arm band. By doing so, the frequency can be kept at f ₁ even if the loop antenna 201 is shortened. Regarding the value of the resistance plate 221 , since this value is used to compensate for the increase or decrease of the inductance, ΔCtotal of Equation 12 can be used as a capacity for compensating the inductance change ΔLtotal. That is, when the length of the loop antenna is shortened by Δα, the amount of change in the equivalent capacitance connected in parallel to the loop antenna is ΔCtotal. May be changed at any time.

That is, the variable capacitance diode 206 has
It suffices to apply a DC voltage that is suitable for that. It also means that the necessary resistors need to be installed.

FIG. 12 is a diagram showing the structure of the variable resistor 204. The connector 202 allows the arm bands 222a,
The loop antenna 201a included in the inside of 22b ,
201b is connected. The arm band 222a on the side where the loop antenna 201a is located further includes a resistance plate 221. In the resistance plate 221, sections having different resistance values are continuously connected, and each of the sections has an electrically conductive hole 220. These holes 220 have a structure penetrating from the front surface to the back surface of the arm band. One of the holes 220 is a connector 202
It is connected to the projection inside and connected to the loop antenna 201b.

FIG. 13 is a longitudinal sectional view of the connector 202. A metal fitting 224 is attached to the tip of the loop antenna 201b, and a metal fitting 225 is attached in the middle of the arm band 222a having the loop antenna 201a. The metal fittings 224 and 225 are electrically connected to the loop antennas 201a and 201b.
6, a hook 227 and a retainer 228 are used. The loop antenna 201 is crimped by these three metal fittings.
a and 20 lb are joined.

The metal fitting 224 has a projection 223. This is the hole 22 provided on one side of the arm band 222a.
0. The hole 220 is electrically conductive and is formed in the resistance plate 221. The projection 223 and the hole 220 have a constricted cross section to ensure electrical conduction. Thus, the resistance plate 221
Is connected to the metal fitting 224 and the loop antenna 20lb.

When the loop antenna 201 is long, the protrusion 223 is provided in the hole 2 on the tip side of the loop antenna 201a.
It will be inserted into 20. Then, since the resistance plate 221 is used with a longer length, the resistance value between the projection 223 and the variable capacitance diode 206 increases. Therefore, the voltage applied to the cathode of the variable capacitance diode 206 increases, and the loop antenna 201
The capacitance is reduced in a manner to compensate for the increase in the inductance of the device, and as a result, no detuning occurs and a constant sensitivity can be maintained.

Conversely, if the loop antenna 201 becomes shorter, the hole 220 of the loop
, The resistor plate 221 is used with a shorter length, the applied voltage is reduced, and the amount of the variable capacitance diode 206 is increased in a form to compensate for the decrease in the inductance of the loop antenna 201, thereby preventing the tuning deviation. You can do it.

As described above, when the antenna circuit of the present invention is used, even if the length of the arm band integrated with the loop antenna is changed, the tuning deviation is automatically compensated, so that the sensitivity is improved. Can always be kept constant.

Further, it goes without saying that the present invention can be applied to a circuit in which the antenna circuit is of a balanced output type as shown in FIG.

FIG. 15 is an antenna circuit diagram of the present invention in which a variable capacitance diode is attached to a conventional antenna circuit, but the configuration is different from that of the embodiment shown in FIG.
FIG. 15 shows an embodiment in which a deviation of the resonance frequency of the antenna circuit is automatically compensated for when the loop antenna is worn on the arm and when it is not worn.

The loop antenna 301 has a connector 302
The part can be detached. At the same time, the connector 302 serves as a switch for DC-electrically connecting the loop antenna 301 and the capacitor 304. The connector 302 may be located at any position of the loop antenna 30l. A DC voltage is applied from a terminal 303a via a resistor 303. The terminal 315 is a terminal for monitoring a DC voltage. The capacitor 305 connected in series and the variable capacitance diode 3
Reference numeral 06 denotes a capacitor provided so that the wireless device can tune to a target frequency. In other words, it is a tuning capacitor. Then, a DC voltage for channel selection is applied from the terminal 311 via the resistor 307, and the capacitance of the variable capacitance diode is determined.

The antenna circuit according to the present invention is characterized in that, apart from the above-described variable capacitance diode 306 for tuning, a variable capacitance diode 309, a capacitor 308 connected in series therewith, and a DC voltage The point is that a resistor 310 for application and a terminal 312 are provided.

First, in a state where the loop antenna 301 does not go around the arm, the loop antenna 301 is used by using the tuning capacitor 305 and the variable capacitance diode 306.
It is assumed that the tuning is achieved by forming a resonance circuit. In this state, it is assumed that the loop antenna 301 is cut off at the connector 302 and the loop antenna 301 is connected to the connector 302 this time around the arm.

Then, the value of the inductance of the loop antenna 301 changes due to the influence of the arm of the human body, and the resonance frequency of the antenna circuit is shifted as compared with the case where the arm does not go around. Therefore, by changing the DC voltage applied to the variable capacitance diode 310, the capacitance of the capacitor connected in parallel to the loop antenna 301 is equivalently changed, and the antenna circuit is set to the resonance frequency when the antenna does not go around the original arm. Retune. Thus, the sensitivity of the wireless device can be stably maintained without a shift in the resonance frequency due to the influence of the arm. Needless to say, even if the user goes around the arm first and removes it from the arm, these operations can correct the deviation of the resonance frequency.

The high-frequency signal of the wireless device is amplified by a high-frequency circuit connected to the terminal 313, and a stable output can be obtained.

FIG. 16 is a circuit block diagram showing an embodiment of a wrist-worn receiver incorporating the antenna circuit of the present invention.

The signal received by the loop antenna 301 is
High-frequency amplifier circuit 3 passing through antenna circuit 320 of the present invention
The signal is amplified at 24, mixed with a signal from the local oscillation circuit 325, and converted to an intermediate frequency. Further, the signal is detected by the detection circuit 328 via the amplification circuit 327, and the demodulated signal is processed by the reproduction circuit 329 to obtain various information signals.

For example, it is assumed that the user has not worn the arm first. In this state, the DC voltage from the tuning circuit 330 is applied to the terminal 311 and tuned to a certain frequency f ₁ to receive a high-frequency signal. Then, at the output of the intermediate frequency amplifying circuit 327, the high frequency amplifying circuit 324
The AGC circuit 331 is connected to adjust the gain of the AGC. With this circuit, the input signal of the detection circuit 328 is always adjusted to a constant level.

FIG. 17 is a spectrum diagram showing the resonance characteristics of the antenna circuit in this state. Resonance characteristics 3
At the 40 highest gain frequency is the signal spectrum 34l.

Next, it is assumed that the connector 302 is cut off, and the loop antenna 301 is cut off from the antenna circuit 320 by direct current. Then, the voltage of the terminal 315 rises from the ground potential to the power supply potential. Then, the loop antenna 301 to be attached to the arm is turned around the arm and connected to the connector 302. Then, the terminal 315 becomes the ground potential again. Here, the DC voltage from the tuning circuit 330 does not change. However, in the switch circuit 321 , when the terminal 315 becomes the ground potential, a signal for stopping the operation of the AGC circuit 331 is output. Further, a signal for operating the frequency correction circuit 322 is output. Further, a signal for operating the frequency correction data output circuit 323 is output.

In this state, since the AGC circuit 331 does not operate, the output of the intermediate frequency amplifier 327 is proportional to the output level of the antenna circuit 320. Then, the resonance frequency of the antenna circuit, in order to attached to the arm, offset from the frequency f ₁ before mounting, and is f _2.

At this time, the frequency correction data output circuit 32
3 outputs a signal such that the resonance frequency is shifted by a minute frequency Δf with respect to the frequency f ₂ that is currently resonating.

Upon receiving this signal, the frequency correction circuit 322
Outputs a DC voltage corrected for Δf, is applied to the terminal 312, and the antenna circuit 320 has a resonance frequency of f ₂ + Δf.

FIG. 18 is a diagram showing resonance characteristics when the resonance frequency becomes f ₂ + Δf. At this time, a signal having a level proportional to the resonance characteristic of the antenna circuit 320 is obtained from the output of the intermediate frequency amplification circuit 327. That is, in this case, the level of this output is increased by the amount that the signal gain 345 is increased to the signal gain 344. This output is previously inputted to the frequency correction data output circuit 323 is compared with the leveling Le when the resonance frequency f ₂ which had been stored, is greater, the frequency of f ₂ + △ f is selected. Smaller, the frequency of f ₂ is selected. f ₂ + △
When the level of f is large, that is, when the signal gain is increased to 344 as in the case of FIG. 16, the frequency correction data output circuit 323 outputs a signal so as to resonate at a frequency higher by Δf.

Upon receiving this signal, the frequency correction circuit 322
Newly determines a DC voltage, applies a DC voltage to the terminal 312, and the antenna circuit 320 has a resonance frequency equal to f ₂ + 2 △ f. And the intermediate frequency amplification circuit 32
7 is compared with the level of the resonance frequency of f ₂ + Δf detected immediately before, that is, the level proportional to the signal gain 344 in FIG. Is selected by the frequency correction data output circuit 323.

These series of operations are repeated, and the intermediate frequency amplifying circuit 32 whose resonance frequency is f ₂ + n △ f (n is an integer) is used.
7 is lower than the level at f ₂ + (n−1) △ f, the frequency correction data output circuit 323 sets the resonance frequency to f ₂ + (n−1) △ f. The signal is finally selected and a signal is output to the frequency correction circuit 322. And
Upon receiving this signal, the frequency correction circuit 322 outputs the newly set final DC voltage. At the same time, a signal indicating the end of correction is output to the switch circuit 321. Upon receiving the correction end signal, the switch circuit 32l holds the signal for stopping the operation of the frequency correction data output circuit 323 and the last DC voltage of the frequency correction circuit 322, and outputs the stop signal. Further, a signal for restarting the AGC circuit 331 is output and sent to the AGC circuit 331. In this way, the frequency correction operation ends.

FIG. 19 is a timing chart showing a signal change of a circuit in which the antenna circuit of the present invention operates to automatically correct the deviation of the resonance frequency.

The series of operations described above are shown in this figure.

Before the wearing of the wrist, the antenna circuit 320 maintained the resonance frequency f _1. However, the connector of the wristband was cut off to fit the wrist into the wrist. Then, the voltage 3 of the terminal 315
46 rises to the power supply voltage. At that time, antenna circuit 3
There is almost no signal gain 350 at the frequency f ₁ of 20 because the loop antenna is cut off. Then, an arm band is attached to the arm. Then, the voltage 346 of the terminal 315 decreases to the ground potential. Thus, A
In order to stop the GC circuit 331 and operate the frequency correction data output circuit 323 and the frequency correction circuit 322, a signal 347 for controlling them rises to the power supply voltage.

When the frequency correction data output circuit 323 outputs the correction signal 348 # f, the frequency correction circuit 322
Increases the DC voltage 349 slightly to change the resonance frequency from f ₂ to f ₂ + Δf. Then, the signal gain 350 at the frequency f ₁ of the antenna circuit 320 slightly increases, and the signal 351 level of the intermediate frequency amplifier 327 also slightly increases. In this case, since the AGC circuit 33l is stopped, it is not proportional to the signal gain 350 leveling Le at the frequency f ₁ of the antenna circuit 320.

Since the signal 351 level of the intermediate frequency amplifier 327 has increased, the frequency correction data output circuit 323
In order to change the resonance frequency to f ₂ + 2Δf for the next correction, a correction signal 3482Δf is output.

While repeating the above, n △ f at which the output signal 351 of the intermediate frequency amplifying circuit 327 becomes maximum is searched for.

In FIG. 19, since the signal 351 level of the intermediate frequency amplifying circuit 327 drops for the first time after the correction of 6 △ f, the frequency correction data output is performed to change the resonance frequency to f ₂ + 5 △ f immediately before. The circuit 323 outputs the correction signal 3485 # f, and outputs the signal 3 to the switch circuit 321.
Enter 52. Detecting the trigger pulse of the signal 352,
Frequency correction data output circuit 323 and frequency correction circuit 3
The signal 347 for controlling the signal 22 falls and the frequency correction circuit 322 stops while holding the DC voltage 349 at the time of f ₂ + 5 △ f. At the same time, the signal 347 for controlling the AGC circuit 331 falls, and the AGC circuit 331 operates again. Then, the signal level of the intermediate frequency amplification circuit 327 returns to the level before the 351 series of correction operations, and the correction operation ends.

As described above, the tuning frequency of the antenna circuit 320 when worn on the arm is f ₂ + (n−1) △ f
When Δf is reduced, the frequency f ₁ when not worn on the arm approaches as much as possible. Af may be appropriately selected depending on the resonance characteristics of the antenna circuit. That is, the frequency difference Δf to be corrected at one time is determined in consideration of the correction accuracy and the time required for the correction.

An algorithm for obtaining the resonance frequency that maximizes the output signal 35l level of the intermediate frequency amplifier circuit 327 during the correction operation is a so-called method for obtaining the maximum value of data executed by an electronic computer. Any of them can be used.

In this way, the resonance frequency f ₂ between when worn on the arm and the frequency f ₁ when not worn on the arm is shared.
The deviation of the vibration frequency can be corrected . These operations are all performed automatically, and the resonance frequency is corrected without any trouble for the user .

[0106] The receiving sensitivity is different from that when worn on the arm.
In other cases, the difference due to the frequency shift can be eliminated.

[0107]

As described above, the antenna circuit according to the present invention can be used depending on the length of the loop antenna, that is, the thickness of the arm of the wearer, or when the wearer wears the arm. In order to prevent the resonance frequency of the antenna circuit from changing,
It can be corrected and always tuned to a constant frequency.

[0108] The wrist-mounted radio equipped with such an antenna circuit can be used even when the thickness of the arm of the wearer changes and the length of the arm band changes, or when the radio is mounted on the wrist. Otherwise, it is possible to automatically and stably receive a constant frequency signal with a constant sensitivity without special adjustment.

[Brief description of the drawings]

FIG. 1 is an embodiment diagram showing a connector portion of a loop antenna of an antenna circuit according to the present invention.

FIG. 2 is an equivalent circuit diagram of the antenna circuit of the present invention.

FIG. 3 is a diagram showing a relationship between an area A (△ α) and a variation Δα of a length of a loop antenna.

FIG. 4 is a view of FIG. 1 as viewed from the side.

FIG. 5 is an embodiment diagram showing a connector portion of a loop antenna of the antenna circuit of the present invention.

FIG. 6 is a view of FIG. 5 as viewed obliquely from above.

FIG. 7 is a diagram showing an embodiment in which the antenna circuit of the present invention is applied to a wrist-mounted radio.

FIG. 8 is a diagram showing an embodiment of an antenna circuit according to the present invention.

FIG. 9 is a diagram showing an example of a conventional antenna circuit.

FIG. 10 is a diagram showing resonance characteristics of the antenna circuit when the length of the loop antenna is long.

FIG. 11 is a diagram showing resonance characteristics of the antenna circuit when the length of the loop antenna is short.

FIG. 12 is a view for explaining a mechanism of a variable resistor in a connector portion when the antenna circuit of the present invention is applied to a wrist-mounted radio device.

FIG. 13 is a longitudinal sectional view of a connector section.

FIG. 14 is a diagram showing an embodiment of the antenna circuit of the present invention.

FIG. 15 is a diagram showing an embodiment of the antenna circuit of the present invention.

FIG. 16 is a circuit block diagram showing an embodiment of an arm-mounted wireless device incorporating the antenna circuit of the present invention.

FIG. 17 is a diagram showing resonance characteristics of the antenna circuit when the resonance frequency is f ₁ when the arm is not worn.

FIG. 18 is a diagram showing the resonance characteristics of the antenna circuit when the resonance frequencies are f ₂ and f ₂ + Af when the arm is worn.

FIG. 19 is a timing chart showing a signal change of a circuit in which the antenna circuit of the present invention operates to automatically correct the deviation of the resonance frequency.

[Explanation of symbols]

10l, 102: arm band 103: buckle 104, 106: loop antenna 104a, 106a: inductance of loop antenna 105: metal plate 107a: The electrical coupling capacity of the connector. 108a... Another electric coupling capacitance constituting a resonance circuit. 109a, 109b · terminal 110 ····· Curve representing A (△ α) 111 ····· Arm band 112 ····· Loop antenna 113 ···· ········ Radio unit 201, 20la, 201b ····· Loop antenna 202 ····· Connector 203, 209 ··· Resistor 204 ······ Variable resistors 205, 207, 210 ... Capacitor 206 ... Variable capacitance diode for resonance frequency deviation compensation 208 ... Variable capacitance diode for channel selection 211 ... ··· Ground 212 and 214 · DC voltage application terminal 213 ··· High frequency signal output terminal 220 ··· Hole 22l ··· Resistor plates 222a and 222b · Arm Band 223 ... ··· Projections 224, 225 · Fittings 226 ····· Shaft 227 ···· Hooks 228 ········································ Variable capacitance diodes 232, 233 Variable tuning diodes 234, 235 High frequency choke coils 236, 237 Capacitors 238, 239 High frequency signal output terminals 301 · Loop antenna 302 · · · · · · Connectors 303, 307 and 310 · · · Resistors 304, 305 and 308 · · · Capacitors 306 and 309 · · · Variable capacitance diodes 311, 312, 313, 315 and 303a · ·・ ・
, Terminal 314, ground 320, antenna circuit 321, switch circuit 322, frequency correction circuit 323, ... Frequency correction data output circuit 324 ... High frequency amplifier circuit 325 ... Local oscillation circuit 326 ... Mixing circuit 327 Frequency amplification circuit 328 ··· Detection circuit 329 ··· Reproduction circuit 330 ··· Tuning circuit 331 ··· AGC circuit 340, 342, 343 ·・ ・ ・ ・ ・ ・ Resonance characteristics 341 ・ ・ ・ ・ ・ ・ ・ Signal gain when the resonance frequency is f ₁ when the arm is not worn 344 ・ ・ ・ ・ ・ ・ ・ Resonance frequency is f ₂ + △ when the arm is worn
In signal gain 345 ....... arm when mounting the case of f, signal gain 346 ....... terminal 3l5 DC voltage 347 ....... AGC when the resonance frequency is f ₂ A signal 348 for controlling the circuit 331, the frequency correction circuit 322, and the frequency correction data output circuit 323...
349... Frequency correction data output circuit 322
The output voltage 350 of the antenna circuit 320 is f
Signal gain at ₁ 351... Signal of intermediate frequency amplifier circuit 327 352... Frequency correction data output circuit 323
Is a signal for controlling the switch circuit 32l 353... A time interval in which the antenna circuit 320 keeps the resonance frequency indicated by each.

Claims (4)

(57) [Claims] 1. A loop antenna integrated with an arm band to be worn on an arm, and a first variable capacitance diode connected to the loop antenna is configured to resonate at a specific frequency . In the antenna circuit, the loop antenna has a variable length, and a second variable capacitance diode connected to the antenna circuit, and a capacitance of the second variable capacitance diode is changed as needed according to the length of the loop antenna. A voltage generating circuit for generating a control voltage to be applied to the second variable capacitance diode for changing the voltage of the second variable capacitance diode .
An antenna circuit for automatically correcting a shift in resonance frequency . 2. A loop antenna provided on an arm band, band coupling means for attaching and detaching the arm band to an arm, and a variable capacitance diode forming a resonance circuit with the loop antenna.
In arm-attached type radio apparatus, comprising: a de, and have a control means for controlling so as to change the capacitance value of the variable capacitance diode to a predetermined value in the arm-worn and the arm is not mounted in the loop antenna, the The front of the loop antenna between when the arm is worn and when the arm is not worn
An arm-mounted radio device, which automatically corrects a deviation of a resonance frequency of the resonance circuit . Wherein the loop antenna includes a first antenna body provided within the first wrist band, a second antenna element provided in the second wrist band, and characterized in that it consists Wrist-mounted radio. Wherein said band coupling means, said first-en
It has a detection means for detecting whether a container body has an electrical coupling between the second antenna element, wherein the control unit, according to claim 3, characterized in that it is controlled by the detection means The wrist-mounted radio described.