JP2008089496A - Antenna circuit, receiving circuit, and timepiece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To raise the sensitivity of an MI magnetometric sensor to be used for an antenna circuit. <P>SOLUTION: The antenna circuit 42 has the MI magnetometric sensor Z1 being a magnetic field detecting means whose electric property changes according to changes in a magnetic field, a high-frequency signal generator S1 for applying a high-frequency signal to the magnetometric sensor Z1, and a detection means for detecting a received signal obtained by the magnetometric sensor Z1. The magnetometric sensor Z1 is composed of a body 102 in a meandrous shape which is made of magnetic thin wire or a thin film of magnetic material, and has a plurality of linear portions 107 stretching approximately in the same direction and arranged approximately in parallel individually, and turning portions 108 connecting between the ends of adjoining linear portions, and a pair of leads 106 stretching from both ends of the body. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an antenna circuit using a magnetic sensor, a receiving circuit, and a timepiece including the receiving circuit.

  In recent years, a technique for forming an antenna using a magnetic sensor using a magneto-impedance effect element (MI element) has been proposed (for example, Patent Document 1). As described in Patent Document 1, 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 refers to an effect that when an external magnetic field is applied to a soft magnetic material that is energized with a minute high-frequency current, the impedance of the soft magnetic material changes sensitively and the output voltage across the soft magnetic material changes.

Therefore, in an antenna circuit using a magnetic sensor using an MI element (hereinafter referred to as “MI magnetic sensor”), a high-frequency signal is caused to flow to cause a skin effect, thereby increasing the sensitivity to magnetic flux, and thus due to the skin effect. Detect impedance changes.
JP 2000-188558 A

  FIG. 5 is a diagram illustrating an example of an antenna circuit using an MI magnetic sensor and a filter circuit following the antenna circuit. In FIG. 5, S1 is a high-frequency signal generator, R1 is a resistor, C1 is a capacitor, and Z1 is an MI magnetic sensor. In the antenna circuit 42 of FIG. 1, the signal from the high frequency signal generator S1 is divided by the resistor R1 and the MI magnetic sensor Z1, and is output through the capacitor C1. The output from the capacitor C1 is envelope-detected by the diodes D1 and D2, and then filtered by a filter circuit 70 constituted by, for example, a resistor R2 and a capacitor C2.

The sensitivity of the current MI magnetic sensor is about 50 mV / G in the case of a normal sensor shape, and is 1 / (5 * 10 ⁴ ) magnetic field detection even if 1 μV signal detection is possible. That is, while it is necessary to receive 10 ⁻⁸ G, only about 2 * 10 ⁻⁵ G can be received. Therefore, for example, the sensitivity is insufficient for use in a radio timepiece.

  For this reason, it is desired to improve the sensitivity of the MI magnetic sensor, that is, to increase the impedance change.

  It is an object of the present invention to provide a highly sensitive antenna circuit using a MI magnetic sensor, a receiving circuit, and a radio timepiece including the receiving circuit.

  An object of the present invention is to provide a magnetic field detecting means whose electrical characteristics change according to a change in a magnetic field, a high frequency signal generating means for applying a high frequency signal to the magnetic field detecting means, and the magnetic field detecting means and the high frequency signal generating means. An antenna circuit having detection means for detecting an obtained received signal, wherein the magnetic detection means is composed of a magnetic thin wire or a thin film of magnetic material, each extending in substantially the same direction and arranged in parallel. Achieved by an antenna circuit comprising: a meander-shaped main body having a straight portion and a folded portion connecting between ends of adjacent straight portions; and a pair of lead lines extending from both ends of the main body. Is done.

  According to the present invention, the portion of the magnetic body can be lengthened, so that the vicinity of the center having a high magnetic flux density can be lengthened. Therefore, the sensitivity can be improved by increasing the impedance change of the high-frequency signal passing portion due to the magnetic flux.

  In a preferred embodiment, the magnetic detection means has a plurality of extensions extending from the end of the folded portion or the linear portion so as to protrude from the main body substantially parallel to the linear portion.

  According to this embodiment, by providing the extension portion, the magnetic body can be made longer in the magnetic path direction, and the magnetic flux collecting effect can be enhanced.

  In another preferred embodiment, the magnetic detection means has an ear-shaped member made of a magnetic material arranged so as to be adjacent to or in contact with the folded portion at the end of the linear portion.

  According to this embodiment, the ear-shaped member attracts the magnetic flux, so that the magnetic flux to the main body can be increased.

  In a more preferred embodiment, a plurality of ear-shaped members are arranged on both sides of the main body.

  In another preferred embodiment, the pair of lead lines each extend substantially perpendicular to the straight line portion and both.

Another object of the present invention is to provide a magnetic field detecting means whose electrical characteristics change in response to a change in the magnetic field, a high frequency signal generating means for applying a high frequency signal to the magnetic field detecting means, and the magnetic field detecting means and high frequency signal generation. Having a detecting means for detecting the received signal obtained by the means, wherein the magnetic detecting means is made of a magnetic thin wire or a thin film of a magnetic material, each extending in substantially the same direction and arranged in a substantially parallel manner. And an antenna circuit having a meander-shaped main body having a folded portion connecting between the ends of the adjacent linear portions, and a pair of lead lines extending from both ends of the main body;
Amplifying means for amplifying the received signal obtained by the antenna circuit;
This is achieved by a receiving circuit comprising: detecting means for detecting a signal output from the amplifying means.

  Another object of the present invention is to provide the receiving circuit, time information extracting means for extracting time information from a standard radio wave signal including time information received and demodulated by the receiving circuit, and time measuring means for measuring time. Time display means for displaying the time measured by the time measuring means, and time correction means for correcting the time measured by the time measuring means based on the time information extracted by the time information extracting means. This is achieved by a timepiece characterized by comprising.

  According to the present invention, it is possible to provide a highly sensitive antenna circuit using a MI magnetic sensor, a receiving circuit, and a radio timepiece including the receiving circuit.

[Watches]
Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2 are a front view of a wristwatch including a receiving circuit according to an embodiment of the present invention, and a cross-sectional view taken along line AA ′ of FIG. 1 (a cross-sectional view at 12 o'clock to 6 o'clock), respectively. The wristwatch 1 includes a watch case 10 that houses a watch module and the like. A watch band 16 for the user to wear the wristwatch 1 on his / her wrist is attached to the outer peripheral portion of the watch case 10 at 6 o'clock and 12 o'clock. A switch 11 for executing various functions of the wristwatch 1 is provided.

  The watch case 10 is formed in an annular short column shape from a metal such as stainless steel or titanium. In addition, an extension part for attaching the watch band 16 is formed on the side part of each position of the watch case 10 at 6 o'clock and 12 o'clock, and the watch band 16 is attached to this extension part. A hole for passing a pin is formed.

  A watch glass 12 is fitted on the upper end portion of the watch case 10 via a seal member 13 so as to close the upper end portion, and a back cover is provided on the lower end portion of the watch case 10 so as to close the lower end portion. A (back) 14 is attached via an O-ring 15. The back cover 14 is formed in a substantially flat shape with a small thickness using a strong metal such as stainless steel or titanium.

  Inside the watch case 10, an upper housing 21 and a lower housing 22 are arranged with their peripheral portions attached to an inner frame provided on the inner peripheral surface of the watch case 10.

  A printed wiring board 30 made of a predetermined resin is disposed on the upper surface of the upper housing 21, and a dial 23 is further disposed on the upper surface, and a ring-shaped parting plate 24 is disposed on the upper surface of the dial 23. Are arranged in contact with the peripheral edge of the watch glass 12. A liquid crystal display panel 25 for displaying time and the like is supported by the upper housing 21 below an opening 23 a formed at a position near 6 o'clock on the dial 23. That is, when the wristwatch 1 is viewed from the front, the time displayed on the liquid crystal display panel 25 through the watch glass 12 can be visually recognized.

  Further, on the upper surface of the dial 23, twelve time letters 23b formed in a substantially rectangular shape in plan view are provided at equal intervals in the circumferential direction, and these time letters 23b are from 1 o'clock to 12 o'clock. It corresponds to each time. In the present embodiment, among these time characters 23b, an MI magnetic sensor 40 using a magnetoresistive effect element whose magnetic resistance changes according to an external magnetic field is formed in the time character 23b corresponding to 12:00. . The MI magnetic sensor 40 functions as an antenna that receives standard radio waves. The MI magnetic sensor 40 is made of a magnetic material patterned on the upper surface of the printed wiring board 30, and the upper surface of the MI magnetic sensor 40 is exposed from an opening formed at a corresponding position on the dial 23. In this embodiment, the MI magnetic sensor 40 as an antenna is installed at the 12 o'clock time character 23b. However, the present invention is not limited to this, and other locations may be used. It may be placed on the element.

  In addition, the upper housing 21 includes an analog pointer mechanism 26 disposed in the vicinity of the center of the watch case 10. The analog pointer mechanism 26 includes a pointer shaft extending upward from a shaft hole formed in the central portion of the dial 23, and a pointer 26a such as an hour hand and a minute hand attached to the pointer shaft. Move the needle over the top.

  A battery 27 is incorporated in the lower housing 22. Further, between the upper housing 21 and the lower housing 22, an analog pointer mechanism 26 and a circuit board 28 connected to the antenna circuit 42 are disposed.

Various circuit elements are arranged on the circuit board 28. The circuit elements include a control IC such as a CPU, an oscillation circuit, a clock circuit that clocks the current time, an antenna circuit (in the antenna circuit, only the MI magnetic sensor 40 is formed in the time character 23b), an antenna circuit And a receiving circuit for amplifying and detecting the output signal of the antenna circuit to extract a time code signal included in the standard radio wave. The control IC corrects the current time by the clock circuit based on the time code in the signal extracted by the receiving circuit, and causes the liquid crystal display panel 25 to display the corrected current time. Alternatively, the analog pointer mechanism 26 is controlled to move the pointer 26a so as to indicate the current time.
[Circuit configuration]
FIG. 3 is a block diagram showing the internal configuration of the circuit of the wristwatch 1. As shown in FIG. 3, the wristwatch 1 includes a CPU 50, an input unit 51, a display unit 52, a ROM 53, a RAM 54, a receiving circuit 44, a time measuring circuit unit 55, and an oscillation circuit unit 56.

  The CPU 50 reads out a program stored in the ROM 53 at a predetermined timing or in response to an operation signal input from the input unit 200, expands the program in the RAM 54, and based on the program to each unit constituting the wristwatch 1 Instructions and data transfer are executed. Specifically, for example, the reception circuit 44 is controlled every predetermined time so that the standard radio wave is received, and the current time data measured by the timing circuit unit 55 is corrected based on the time code signal from the reception circuit 44. Processing, processing for transferring the current time measured by the timing circuit unit 55 to the display unit 52, and the like are executed.

  The input unit 51 includes a switch 11 for instructing execution of various functions of the wristwatch 1, and outputs a corresponding operation signal to the CPU 50 when the switch 11 is operated. The display unit 52 includes the analog pointer mechanism 26 and the liquid crystal panel 25 controlled by the dial plate 23 and the CPU 50, and displays the current time measured by the timing circuit unit 55. The ROM 53 stores the system program, application program, data, etc. for operating the wristwatch 1 and realizing a predetermined function. The RAM 54 is used as a work area for the CPU 50, and temporarily stores programs and data read from the ROM 53, data processed by the CPU 50, and the like.

  As will be described in detail later, the receiving circuit 44 includes an antenna circuit 42, extracts a signal of a predetermined frequency from the signal received by the antenna circuit 42, and outputs the extracted signal to the CPU 50. The clock circuit unit 55 counts the signal input from the oscillation circuit unit 56, clocks the current time, and outputs the current time data to the CPU 50. The oscillation circuit unit 56 always outputs a clock signal having a constant frequency.

  FIG. 4 is a block diagram showing an outline of the receiving circuit 44. As illustrated in FIG. 4, the reception circuit 44 includes an antenna circuit 42, a filter circuit 70, an amplifier circuit 80, a bandpass filter (BPF) 90, and a detection circuit 100. The filter circuit 70 is illustratively a low-pass filter (see, for example, FIG. 5), but is not limited to this, and a band-pass filter (BPF) may be used.

  As will be described with reference to FIG. 5, the antenna circuit 42 includes a high-frequency signal generator S1, a resistor R1, an MI magnetic sensor Z1 (indicated by reference numeral 40 in FIG. 1), a capacitor C1, and diodes D1 and D2. including.

  A signal corresponding to a standard radio wave is output from the antenna circuit 42, and is supplied to the frequency conversion / detection circuit 100 through the filter circuit 70, the amplification circuit 80, and the BPF 90.

  The detection circuit 100 demodulates a standard radio wave signal. The demodulated signal is given to the CPU 50, where it is decoded and time information is extracted.

  In the antenna circuit 42 shown in FIG. 5, the high frequency signal generator S1 generates, for example, a 20 MHz signal. The high frequency signal generator S1 is connected to one end of the resistor R1. The other end of the resistor R1 is connected to one end of each of the MI magnetic sensor Z1 and the capacitor C1. The diodes D1 and D2 function as an envelope detection circuit.

  The operation of the antenna circuit 42 thus configured will be described. The voltage Va at the position (point a) between the resistor R1 of the antenna circuit 42 and the MI magnetic sensor Z1 can be expressed as follows.

Va≈Asinωt · Z (1 + Bsinpt) / (R1 + Z) (1)
(Asinωt: signal of the high-frequency signal generator S1, Z (1 + Bsinpt): signal of the MI magnetic sensor Z1)
As shown in equation (1), the modulation signal has the same format as amplitude modulation (AM), and indicates that the signal of the high-frequency signal generator S1 undergoes amplitude modulation by the magnetic field frequency. Therefore, sidebands due to magnetic field reception appear on both sides of the carrier signal from the high-frequency signal generator S1. Therefore, detection is performed by the envelope detection circuit including the diodes D1 and D2.
[First Embodiment]
Hereinafter, the antenna circuit according to the present embodiment, in particular, the MI magnetic sensor Z1 of the antenna circuit will be described in more detail. FIG. 6 is a diagram showing in detail the part of the antenna circuit according to the first embodiment of the present invention. The MI magnetic sensor Z1 according to the first embodiment is composed of a magnetic thin film or a thin film of magnetic material formed on a base (not shown) such as a film. As shown in FIG. 6, the MI magnetic sensor Z1 has a meander-shaped main body 102. The main body 102 includes a straight portion 107 and a folded portion 108 formed between the straight portions. Both ends of the main body 102 function as electrodes, and lead wires 104 and 106 extend from the electrodes, respectively. One lead wire 104 is connected to the resistor R1 and the capacitor C1, and the other lead wire 106 is grounded. .

In the present embodiment, the antenna body 102 has a deformed meander shape, so that the magnetic flux density can be increased, thereby increasing the impedance change due to the magnetic flux and capturing the change with the antenna circuit. It is easy.
[Second Embodiment]
Next, an MI magnetic sensor according to a second embodiment will be described with reference to FIG. As shown in FIG. 7, the main body 102 of the MI magnetic sensor Z <b> 1 according to the second embodiment includes an end portion of the straight portion 107 and a folded portion 108, substantially parallel to the straight portion 107 and from the main body 102. It has the extension part 114 extended so that it may protrude. The extension 114 on the left side of FIG. 7 and the lead wire 104 are not actually in contact with each other.

Thus, by providing the extension part 114, the magnetic flux collection effect can be enhanced. The magnetic flux collecting effect refers to concentrating magnetic lines of force in a limited range of one point. The magnetic flux collecting effect can be enhanced by, for example, a shape that is long in the magnetic path direction. In the second embodiment, the extension 114 is formed so as to extend from the straight portion 107. Thereby, it is possible to make the shape longer in the magnetic path direction.
[Third Embodiment]
Next, an MI magnetic sensor according to a third embodiment will be described with reference to FIG. As shown in FIG. 8, in the third embodiment, the ear-shaped member 126 made of a planar magnetic body is adjacent to the folded portions 108, 108 on the respective sides of the main body 102 of the MI magnetic sensor Z1. 126 is formed. That is, the ear-shaped members 126 and 126 are formed on both ends of the linear portion 107. The ear-shaped member 126 is realized, for example, by forming a thin film of a magnetic material on a base such as a film. The ear-shaped member 126 is disposed adjacent to the folded portions 108 and 108 and the lead lines 104 and 106, but may not be connected to these.

  According to the third embodiment, the magnetic flux to the main body 102 of the MI magnetic sensor Z1 is attracted to the main body 102 of the MI magnetic sensor Z1 by the ear-shaped member 126 made of a magnetic material, thereby increasing the sensitivity of the antenna. It becomes possible.

  In the third embodiment, the ear-shaped member 126 is disposed at a slight distance so as not to be connected to the main body 102. Furthermore, when using a magnetic material having high conductivity such as amorphous metal, the periphery of the ear-shaped member 126 is made an insulator, for example, by forming a layer of an insulating material around the ear-shaped member 126, It is also possible to make it closely contact with 102.

  The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

  For example, in the present invention, the MI magnetic sensor of the antenna circuit 42 has a meander shape (first embodiment), and an extension that protrudes from the folded portion in the same direction as the meander-shaped linear portion. (Second Embodiment) A device in which an ear-shaped member made of a magnetic material is provided in the vicinity of a folded portion is used. However, the shape of the MI magnetic sensor is not limited to that described above, and an extension portion may be provided in the folded portion as in the second embodiment, and an ear-shaped member may be provided in the vicinity of the folded portion.

  Moreover, in 2nd Embodiment, although the extension part protrudes from the folding | returning part, it is not limited to this, You may comprise so that it may protrude from the edge part of a linear part.

  Further, in the third embodiment, two ear-shaped members are arranged on both sides of the main body. However, the present invention is not limited to this, and may be arranged on one side, or three or more ear-shaped members. May be arranged.

FIG. 1 is a front view of a wristwatch including a receiving circuit according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG. FIG. 3 is a block diagram showing the internal configuration of the watch circuit according to the present embodiment. FIG. 4 is a block diagram showing an outline of the receiving circuit according to the present embodiment. FIG. 5 is a diagram illustrating an antenna circuit according to an embodiment of the present invention. FIG. 6 is a diagram showing in detail the part of the antenna circuit according to the first embodiment of the present invention. FIG. 7 is a diagram showing in detail the part of the antenna circuit according to the second embodiment of the present invention. FIG. 8 is a diagram showing in detail the part of the antenna circuit according to the third embodiment of the present invention.

Explanation of symbols

42 Antenna circuit 44 Receiving circuit 50 CPU
51 Input Unit 52 Display Unit 55 Timekeeping Circuit Unit 56 Oscillation Circuit Unit 70 Filter Circuit 80 Amplification Circuit 90 BPF
100 Frequency Conversion / Detection Circuit S1 High Frequency Signal Generator R1 Resistance Z1 MI Magnetic Sensor C1 Capacitor D1, D2 Diode

Claims (7)

Magnetic field detection means whose electrical characteristics change in response to changes in the magnetic field, high frequency signal generation means for applying a high frequency signal to the magnetic field detection means, and reception signals obtained by the magnetic field detection means and the high frequency signal generation means An antenna circuit having detection means for detecting,
The magnetic detection means is composed of a magnetic thin wire or a thin film of magnetic material, each extending in substantially the same direction and arranged substantially in parallel, and a folded portion connecting between the ends of adjacent linear portions An antenna circuit comprising: a meander-shaped main body having a pair of lead wires extending from both ends of the main body.   3. The magnetic detection unit according to claim 2, wherein the magnetic detection unit includes a plurality of extensions extending from the end of the folded portion or the linear portion so as to protrude from the main body substantially parallel to the linear portion. Receiver circuit.   The said magnetic detection means has an ear-shaped member by the planar magnetic body arrange | positioned so that it may adjoin or contact the said folding | turning part in the edge part of the said linear part. Receiver circuit.   The receiving circuit according to claim 3, wherein a plurality of ear-shaped members are arranged on both sides of the main body.   5. The antenna circuit according to claim 1, wherein each of the pair of lead lines extends in a direction substantially perpendicular to the straight line portion. 6. Magnetic field detection means whose electrical characteristics change in response to changes in the magnetic field, high frequency signal generation means for applying a high frequency signal to the magnetic field detection means, and reception signals obtained by the magnetic field detection means and the high frequency signal generation means A detecting means for detecting, the magnetic detecting means comprising a thin magnetic wire or a thin film of a magnetic material, each extending substantially in the same direction and arranged substantially in parallel, and adjacent straight portions An antenna circuit having a meander-shaped main body having a folded portion connecting between the ends, and a pair of lead lines extending from both ends of the main body;
Amplifying means for amplifying the received signal obtained by the antenna circuit;
And a detecting means for detecting the signal output from the amplifying means. A receiving circuit according to claim 6;
Time information extracting means for extracting time information from a standard radio wave signal including time information received and demodulated by the receiving circuit;
A time measuring means for measuring time;
Time display means for displaying the time measured by the time measuring means;
A timepiece comprising: time correction means for correcting the time counted by the timekeeping means based on the time information extracted by the time information extraction means.