JP4645730B2 - Antenna device, receiving device and radio clock - Google Patents

Description

  The present invention relates to an antenna device and a receiving device that receive radio signals, and a radio timepiece that receives standard radio waves including a time code.

  In general, various antennas such as a linear antenna, a wound bar antenna, and a planar antenna are known. Further, in a radio timepiece that receives a standard radio wave, a wound bar antenna is used because it is necessary to mount the antenna on a small clock body.

As prior arts related to the present invention, Patent Documents 1 and 2 disclose antenna devices that receive a radio signal by reacting to a magnetic field component of a radio wave using a magnetoresistive effect element. In Patent Document 3, a magnetic thin film is formed on a diaphragm formed by a MEMS (Micro Electro Mechanical Systems) fabrication technique, and a change in the resonance frequency of the diaphragm is detected while vibrating the diaphragm. Thus, a resonance type magnetic sensor for measuring an external magnetic field is disclosed.
JP 2000-188558 A JP 2007-124335 A JP 2005-201775 A

  At present, the present inventors have provided a magnetic body in a vibrating body formed by using a MEMS fabrication technique, resonates the vibrating body with a radio wave signal, and converts the resonance motion into an electric signal, thereby obtaining a specific frequency band. We are developing an antenna device that receives radio signals.

  However, in the antenna device configured as described above, the vibrating body has a characteristic of resonating only when a radio signal in a specific frequency band having a narrow band arrives. There was a problem that selective reception was not possible.

  An object of the present invention is to enable reception of a plurality of channels of radio waves in an antenna device that receives radio waves in a specific frequency band by resonating a vibrating body with radio wave signals and converting the resonance motion into electric signals. It is.

In order to achieve the above object, the invention according to claim 1
A radio wave having a characteristic that vibrates at a predetermined natural frequency and that is displaced by receiving an external magnetic field, and a conversion unit that converts the motion of the vibrator into an electric signal, and having a frequency band that resonates the vibrator When a signal arrives, the vibrating body resonates due to the magnetic field component of the radio signal, and the resonance is converted into an electric signal by the conversion means, so that the radio signal in the frequency band is converted into an electric signal and captured. An antenna device including an antenna unit,
A plurality of the antenna units are provided with different natural frequencies of the vibrating body.

The invention according to claim 2 is the antenna device according to claim 1,
The plurality of antenna portions are formed on a one-chip substrate.

The invention according to claim 3 is the antenna device according to claim 1,
Switch means for selectively sending an electrical signal from any one of the plurality of antenna units to a subsequent stage is provided.

The invention according to claim 4
An antenna device according to claim 3,
An amplifier for amplifying an electrical signal sent from the antenna device via the switch means;
A demodulator that performs demodulation processing on the signal amplified by the amplifier;
It is provided with the receiving apparatus characterized by the above-mentioned.

The invention according to claim 5 is the receiving apparatus according to claim 4,
The antenna device, the amplifier, and the demodulator are formed on a one-chip semiconductor substrate.

The invention described in claim 6
A radio timepiece that receives a standard radio wave by the receiving device according to claim 4, demodulates a time code included in the standard radio wave, and corrects the time based on the time code.

  According to the present invention, it is possible to receive radio signals of a plurality of channels having different frequency bands by a plurality of antenna units having different natural frequencies of the vibrator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram showing an entire radio timepiece according to an embodiment of the present invention.

  The radio-controlled timepiece 1 of this embodiment is any one of a plurality of MEMS antennas 10, 10a to 10z serving as an antenna unit that receives a standard radio wave modulated by a time code, and a plurality of MEMS antennas 10, 10a to 10z. Switch circuit 108 as a switch means selectively connected to each other, an amplifier 101 for amplifying a received signal input from the MEMS antennas 10 and 10a to 10z via the switch circuit 108, and detecting a time code from the received signal It comprises a detector 102 as a demodulator, a microcomputer 103 that controls the clock as a whole, a time display 104 that performs time display output, a time counter 105 that performs time measurement, and the like. Of these components, the MEMS antenna 10, the switch circuit 108, the amplifier 101, and the detector 102 constitute a radio wave receiver 100 as a receiving device.

  The plurality of MEMS antennas 10, 10 a to 10 z are configured to receive radio signals in different frequency bands, although individual structures will be described later in detail. Standard radio waves are transmitted, for example, by carrier waves in different frequency bands (40 kHz and 60 kHz) in the west and east regions in Japan. Moreover, in foreign countries, it transmits with the carrier wave of a different frequency for every district. The reception frequency bands of the MEMS antennas 10, 10a to 10z are respectively matched with the frequency bands of the standard radio waves in these areas. The plurality of MEMS antennas 10, 10a to 10z constitute an antenna device.

  The switch circuit 108 is a switch formed by combining, for example, a MOS transistor or a bipolar transistor. The switch circuit 108 includes any one of the plurality of output terminals t1, t1,... T1 of the plurality of MEMS antennas 10, 10a to 10z, and the amplifier 101. The input terminal t2 is selectively connected. The connection destination is controlled by a channel selection signal sent from the microcomputer 103.

  The radio wave receiving unit 100 is formed on one semiconductor substrate including the plurality of MEMS antennas 10, 10a to 10z, for example. In addition to the radio wave receiving unit 100, the microcomputer 103 and the time counter 105 can be formed on a single semiconductor substrate.

  First, the overall operation will be described. The microcomputer 103 performs time display output by updating the output data to the time display 104 in synchronization with the time data of the time counter 105. Further, the microcomputer 103 executes a radio wave reception control program to activate the radio wave receiving unit 100 at a predetermined time. Thereby, the standard radio wave transmitted by the carrier wave in the predetermined frequency band is received by the radio wave receiving unit 100, and the time code is detected from the received signal. The microcomputer 103 inputs the detected time code, and obtains an accurate current time from this time code. If there is a difference in the time measured by the time counter 105, this is automatically corrected. By such a control operation, accurate time display is always performed.

  The microcomputer 103 receives current location information from an operation input unit (not shown), and switches the connection of the switch circuit 108 based on the current location information. Each of the MEMS antennas 10, 10a to 10z has a characteristic of receiving standard radio waves in different frequency bands, and the microcomputer 103 selects one of the plurality of MEMS antennas 10, 10a to 10z according to the current location. Select to receive the received signal. As a result, the standard radio wave corresponding to the current location is received, and the time is corrected from the time code.

  If the reception of the time code is not confirmed by the radio wave reception process, the microcomputer 103 sequentially switches the connection of the switch circuit 108 to search for the MEMS antennas 10, 10a to 10z that can confirm the reception of the time code. Control is also performed such that radio waves are received from the MEMS antennas 10, 10a to 10z that have been confirmed to receive codes.

  2 is a perspective view showing a configuration of one MEMS antenna 10 according to an embodiment of the present invention, FIG. 3 is a longitudinal sectional view of the MEMS antenna 10, and FIG. 4 shows an electrical configuration of the MEMS antenna 10. FIG.

  The MEMS antenna 10 is an extremely small antenna (for example, several millimeters or less or a micron-order size) formed on a semiconductor substrate using a MEMS (Micro Electro Mechanical Systems) manufacturing technique, and a magnetic field component of a radio signal. The received radio wave is converted into an electric signal.

  As shown in FIGS. 2 and 3, the MEMS antenna 10 includes a beam portion 12 formed on a substrate 11, spacers 15 and 15 made of an insulator that fixes a part of the beam portion 12, and a beam A magnetic body 13 formed in a movable range of the portion 12, a permanent magnet 14 fixed to the lower side of the beam portion 12, a planar electrode (first electrode) 16 formed on the beam portion 12, and a beam It is composed of a planar electrode 17 (second electrode) or the like formed at a site on the substrate 11 facing the portion 12. Then, a space is provided around the beam portion 12, and the periphery is sealed with a resin 19 or the like in a state where the beam portion 12 can be displaced vertically. Note that the electrode 16 may be shared with the beam portion 12 by making the beam portion 12 itself conductive.

  Among the above configurations, the beam portion 12 and the magnetic body 13 constitute a vibrating body, and the electrodes 16 and 17 constitute conversion means for converting the displacement of the beam portion 12 into an electric signal.

  The beam portion 12 is made of, for example, silicon. The beam portion 12 has a plate-like configuration, the longitudinal direction of the beam portion 12 is oriented along the substrate 11, and some portions (for example, both end portions) are fixed to the substrate 11 via spacers 15 and 15. Is floating on the substrate 11 with a space. The space below the beam portion 12 can be formed by sacrificial layer etching or the like. The unfixed portion vibrates up and down with respect to the substrate 11.

  The natural frequency of the beam portion 12 can be set to a desired frequency based on the length and thickness of the beam portion 12, and in this embodiment, the frequency of one standard radio wave (for example, 40 kHz) is set. Are set to be the same. Moreover, temperature compensation of such vibration characteristics can be performed by appropriately combining SiGe (silicon germanium) and other materials for the beam portion 12.

  In each of the plurality of MEMS antennas 10, 10 a to 10 z, the natural frequency of each beam portion 12 is set to be different, for example, set to be the same as the frequency of a carrier wave of a standard radio wave in a different district or a different country. Has been.

  The planar electrode 16 formed on the beam portion 12 and the planar electrode 17 formed on the substrate 11 are arranged so as to face each other and constitute an electric capacity. For example, the planar electrode 16 is formed by vapor deposition of a metal material. Is. This metal material is preferably made of non-magnetized aluminum or the like. Instead of forming the electrode 16 on the beam portion 12, the material itself forming the beam portion 12 may be doped to add conductivity, and the beam portion 12 itself may be used as an electrode.

  Wirings h1 and h2 are connected to the electrodes 16 and 17 by a normal semiconductor manufacturing process, and the wirings h1 and h2 are drawn on the substrate 11. In FIG. 3, the wirings h1 and h2 are shown in a simplified manner, but actually, the wiring h2 on the substrate 11 side is pulled out to the outside of the MEMS antenna 10 on the substrate 11 and the wiring h1 on the beam portion 12 side is A contact hole is formed in the spacer 15 and led to the substrate 11, and then pulled out to the outside of the MEMS antenna 10 on the substrate 11.

  The spacers 15 and 15 are formed of, for example, a silicon oxide film (SiO 2) or the like in order to provide insulation.

  The permanent magnet 14 on the substrate 11 is for exerting a magnetic force on the magnetic body 13 of the beam portion 12. For example, after forming a ferromagnetic block by sputtering, a ferromagnetic block is formed. It can be formed by applying a strong magnetic field to a body block to magnetize the ferromagnetic material in a specific direction.

  The magnetic body 13 on the beam portion 12 acts to displace the beam portion 12 by generating a repulsive force or an attractive force with respect to the permanent magnet 14 by receiving and magnetizing the magnetic field component of the radio signal. For example, it can be formed by thin film deposition of a magnetic material (for example, soft magnetic material) using sputtering.

  As shown in FIG. 4, the electrodes 16 and 17 of the MEMS antenna 10 constitute a variable capacitor Cv that changes the magnitude of the capacitance when the beam portion 12 is displaced. A capacitive element C1 is connected in series with the variable capacitor Cv on the semiconductor substrate, and a voltage E1 is applied to these series circuits. With such a configuration, the beam portion 12 is displaced to change the capacitance value of the variable capacitor Cv, so that an electric signal (voltage) corresponding to the displacement of the beam portion 12 is output between the terminals of the variable capacitor Cv. It has become.

  Note that the same effect can be obtained by connecting a resistance element in series with the variable capacitor Cv instead of the capacitor C1 of FIG.

  Next, operations of the MEMS antenna 10 and the radio wave receiver 100 having the above-described configuration will be described.

  According to the MEMS antenna 10 having the above configuration, when a standard radio wave in a frequency band (for example, 40 kHz) corresponding to the natural frequency of the beam portion 12 arrives, the magnetic field component of the radio signal exerts an acting force on the beam portion 12. The beam portion 12 resonates, and the beam portion 12 is displaced according to the magnitude of the magnetic field component of the radio signal.

  The displacement of the beam portion 12 becomes a capacitance change of the variable capacitor Cv, and an electric signal corresponding to the capacitance change is output from the MEMS antenna 10 to the amplifier 101 via the switch circuit 108. This electric signal is a signal obtained by converting the incoming standard radio wave into an electric signal almost as it is. This electric signal is amplified by the amplifier 101, and then sent to the detector 102 to detect the time code.

  On the other hand, when a radio wave having a frequency band deviating from the natural frequency of the beam part 12 arrives, the magnetic field component of this radio signal acts on the beam part 12, but at a frequency deviating from the natural frequency of the beam part 12. Since the acting force vibrates, the beam portion 12 is absorbed and canceled by the beam portion 12 and the beam portion 12 does not vibrate. Therefore, the capacitance change of the variable capacitor Cv does not occur, and the signal output of the MEMS antenna 10 becomes almost zero.

  In addition, when the above standard radio waves and radio waves in other frequency bands come in a mixed manner, the operations of the two are operated so as to overlap with each other, so that the radio waves in the frequency band deviating from the natural frequency of the beam portion 12 are cut. Only the standard radio wave is extracted by the MEMS antenna 10 and received. Then, only the standard radio wave signal is sent to the amplifier 101 and the detector 102.

  In FIG. 5, the graph showing the frequency characteristic of a MEMS antenna and the conventional coil type | mold antenna is shown.

  The vibrating body formed by the MEMS manufacturing technique can obtain frequency characteristics such that large resonance is performed only in the narrow frequency range of the natural frequency. Therefore, according to the MEMS antenna 10 having the above configuration, as shown by a solid line in FIG. 5, only a radio wave having a specific frequency f0 is received with a very high Q value, and a radio wave deviating from the specific frequency f0 is greatly cut. Characteristics can be obtained. The dotted line in FIG. 5 shows the frequency characteristics of the coil antenna for comparison. As can be seen from a comparison between the characteristic line of the solid line and the dotted line in FIG. 5, the Q value of the reception gain of the antenna itself of the MEMS antenna 10 is much higher than that of the coil antenna.

  The plurality of MEMS antennas 10 and 10a to 10z formed in the radio wave receiver 100 are set with different values of the specific frequency f0, but the Q value of the reception gain has similar characteristics. is there. Therefore, by selectively switching the MEMS antennas 10, 10a to 10z that perform radio wave reception, it is possible to capture a radio signal from a desired channel in a narrow band.

  According to the MEMS antenna 10 having such a configuration, the antenna can be significantly reduced in size by using the MEMS technology. Further, the MEMS antenna 10 itself receives only radio signals in a specific frequency band like a narrow band filter, and cuts off the input of radio waves that deviate from the specific frequency band. Can be removed. As a result, the operation of the amplification stage is saturated by the input of radio waves outside the band, and there is no inconvenience that the reception sensitivity is lowered by this saturation.

  Also, in coil type antennas, a relatively large change in magnetic flux occurs in the coil and core with radio wave reception, so eddy currents are generated in the surrounding metal, and the reception sensitivity is greatly reduced due to the generation of eddy currents. However, since the MEMS antenna 10 does not generate such eddy current, the receiving sensitivity is not lowered. Therefore, even if there is a metal around it, a high reception sensitivity can be realized if the input of radio waves is not blocked.

  In addition, since the MEMS antenna 10 employs a configuration in which the magnetic body 13 is provided in the beam portion 12 and the permanent magnet 14 is provided below the beam portion 12 to vibrate the beam portion 12, the manufacturing process can be simplified. Manufacturing costs are reduced. Further, since the permanent magnet 14 exerts a magnetic force on the magnetic body 13 of the beam portion 12, the displacement of the beam portion 12 due to the action of the magnetic field component of the radio signal can be increased.

  Further, the planar electrodes 16 and 17 facing each other are formed on the substrate 11 and the beam portion 12, and an electric signal corresponding to the displacement of the beam portion 12 is output by the variable capacitor Cv composed of the electrodes 16 and 17. Therefore, the displacement of the beam portion 12 can be reliably converted into an electric signal with a relatively simple configuration.

  Furthermore, according to the antenna device of this embodiment, since the plurality of MEMS antennas 10 and 10a to 10z having different reception frequency bands are provided, it is possible to receive radio waves of a plurality of channels from these. In addition, since the individual MEMS antennas 10, 10a to 10z are very small, the chip area of the whole antenna device is not so large even if the plurality of MEMS antennas 10, 10a to 10z are provided. Further, since all the MEMS antennas 10, 10a to 10z can be simultaneously manufactured by the same MEMS manufacturing process, the manufacturing cost of the antenna device is greatly increased even if the plurality of MEMS antennas 10, 10a to 10z are provided. Do not increase it.

  Further, according to the antenna device and the radio wave receiving unit 100 of this embodiment, the switch circuit 108 can switch the connection between any one of the plurality of MEMS antennas 10, 10a to 10z and the subsequent circuit (amplifier 101). Therefore, it is possible to selectively receive radio waves of one channel while radio waves of a plurality of channels are transmitted together. Note that the switch circuit 108 can be omitted in a case where radio signals of a plurality of channels are received together or in a place where the radio signals of a plurality of channels are exclusively transmitted.

  In addition, according to the radio timepiece 1 of this embodiment, the radio wave receiving unit 100 including the MEMS antennas 10, 10a to 10z can be configured extremely small. In addition, since the MEMS antenna 10 itself has a narrow band filter characteristic, it is not necessary to separately provide a narrow band filter or the like, and the circuit of the radio wave receiving unit 100 can be simplified and the mounting area can be reduced. it can. Therefore, an antenna and a receiving circuit can be mounted on a small device such as a wristwatch body with a margin.

[First Modification of MEMS Antenna]
FIG. 6 is a longitudinal sectional view showing a first modification of the MEMS antenna.

  The MEMS antenna 10A of the first modification is configured such that a relatively large electric signal can be taken out from the MEMS antenna 10A by providing an electrode also above the beam portion 12 (on the opposite side of the substrate 11). The basic configuration is the same as that of the MEMS antenna 10 of FIG. Similar components are denoted by the same reference numerals and description thereof is omitted.

  In the MEMS antenna 10 </ b> A according to the first modification, a plate-like cover plate 20 is provided so as to cover the upper portion of the beam portion 12, and a planar electrode (third electrode) 21 is formed on the cover plate 20. . The cover plate 20 is formed in a state of floating from the beam portion 12 via spacers 22 and 22, for example, so as not to prevent free displacement of the beam portion 12.

  Such a cover plate 20 can be formed by the same material and manufacturing process as the beam part 12, for example. Further, the cover plate 20 is formed by increasing the thickness or increasing the hardness, for example, so as not to vibrate unlike the beam portion 12.

  The electrode 21 can be formed by the same material and manufacturing process as the electrode 16 of the beam portion 12, and the spacers 22 and 22 can be formed by the same material and manufacturing process as the spacers 15 and 15 that support the beam portion 12. it can. The spacers 22 and 22 are formed, for example, so as to overlap the spacers 15 and 15 that support the beam portion 12.

  FIG. 7 is a circuit diagram showing an electrical connection configuration of the MEMS antenna according to the first modification.

  As shown in FIG. 7, the three electrodes 17, 16, and 21 constitute two variable capacitors Cv and Cv <b> 2 that change their electric capacities when the beam portion 12 is displaced. Specifically, one electrode 16 of the beam portion 12 and the electrode 17 on the substrate 11 side constitute one variable capacitor Cv, and the electrode 16 of the beam portion 12 and the electrode 21 of the cover plate 20 constitute the other variable capacitor Cv2. The The two variable capacitors Cv and Cv2 are connected in series, and a constant voltage E1 is applied to these series circuits.

  With such a configuration, when the beam portion 12 is displaced, the capacitance values of the two variable capacitors Cv and Cv2 change in opposite directions. As a result, an electrical signal corresponding to the displacement of the beam portion 12 is output between the terminals of the variable capacitor Cv. According to this configuration, the amplitude of the output voltage can be increased nearly twice as compared with the above-described circuit shown in FIG.

[Second Modification of MEMS Antenna]
8A and 8B show a second modification of the MEMS antenna. FIG. 8A is a longitudinal sectional view, and FIG. 8B is a plan view of a substrate surface.

  The MEMS antenna 10E of the second modified example uses a coil magnet (electromagnet) 25 instead of a permanent magnet as a configuration for applying a magnetic force to the magnetic body 13 of the beam portion 12. The other configuration is substantially the same as the configuration of FIG. 2, and the same configuration is denoted by the same reference numeral and description thereof is omitted.

  As shown in FIG. 8B, the coil magnet 25 is formed by winding a plurality of wires, and applies a predetermined magnetic force to the magnetic body 13 by flowing a constant current through the wound wires. In this embodiment, the coil magnet 25 is disposed below the magnetic body 13 on the substrate 11.

  The coil magnet 25 is formed at the same time as the electrode 17E, for example, by adding a wiring pattern of the coil magnet 25 to the mask pattern in the vapor deposition process for forming the electrode 17E on the substrate 11. As shown in FIG. 8B, a gap 171 is provided in the central part of the electrode 17E, and a winding wire of the coil magnet 25 is formed in this part. As for the wound wiring, the inner wiring is drawn out by the multilayer wiring.

  In addition, a slit 172 is formed from the central portion of the electrode 17E to one end, and a lead wire extending from the winding wire of the coil magnet 25 to the external terminals T25a and T25b is formed in the slit 172 portion. Thus, by providing the electrode 17E with the slit 172 so that the electrode 17E does not surround the entire circumference of the winding wire of the coil magnet 25, the electrode 17E can be used when a current is supplied to the coil magnet 25 or when the current is stopped. Thus, an eddy current that circulates around the winding wiring is avoided from being generated around the winding wiring, and the coil magnet 25 is not affected by this eddy current.

  According to the MEMS antenna 10E of the second modification, a predetermined magnetic force can be exerted from the coil magnet 25 to the magnetic body 13 by flowing a constant current through the coil magnet 25 when receiving radio waves. And the radio wave reception of a predetermined frequency band can be performed by the operation | movement similar to 1st Embodiment.

  Further, according to the MEMS antenna 10E of the second modified example, since the step of forming the permanent magnet can be omitted from the semiconductor manufacturing process of the MEMS antenna 10E, the manufacturing process of the MEMS antenna 10E can be simplified. .

  Moreover, the effect that the magnitude of the magnetic force exerted from the coil magnet 25 to the magnetic body 13 of the beam portion 12 can be changed by adjusting the current flowing through the coil magnet 25 is obtained.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the MEMS antenna 10 of the above-described embodiment and the first and second modifications thereof, the magnet 14 and the coil magnet 25 are disposed below the beam portion 12, but may be disposed above via a spacer, It can be arranged on the side or variously changed. Furthermore, a magnet or a coil magnet may be retrofitted in a step different from the MEMS manufacturing process in which the MEMS antenna 10 is formed on the chip.

  Moreover, although the example which formed the MEMS antenna 10, 10a-10z on the silicon substrate was shown in the said embodiment, it is not restricted to a silicon substrate, For example, it can also integrate on a glass substrate, an organic material, etc. . Further, the beam portion 12 whose both ends are supported and the central portion vibrates up and down is exemplified as the vibrating body. For example, a cantilever type vibrating body supported in a cantilever manner or a vibrating body having a tuning fork structure is applied. You may do it.

  Moreover, although the example which formed the magnetic body 13 in a part of beam part 12 was shown in the said embodiment, you may make it form a magnetic body thinly in the whole beam part 12. FIG. Moreover, you may make it comprise the beam part 12 itself from a magnetic body. In addition, a magnet that exerts a magnetic force on the magnetic body may be omitted as long as it receives a magnetic field component of a magnitude that can be displaced only by the magnetic body upon receiving the magnetic field component of the radio wave signal.

  Moreover, in the said embodiment, although the example which match | combined the MEMS antennas 10 and 10a-10z with the frequency band of the standard radio wave of each district was shown, the radio wave to receive is not restricted to the standard radio wave including a time code, The antenna device and radio wave receiver of the present invention can be used for various radio wave receptions. In addition, although the example in which the natural frequency of the beam portion 12 is formed to coincide with the frequency band of the received radio wave is shown, when the beam portion 12 actually resonates, the frequency slightly deviates from the original natural frequency. In this case, the natural frequency may be formed by reflecting this deviation in the frequency band of the received radio wave.

  Further, the plurality of MEMS antennas 10, 10a to 10z are formed to have characteristics in which the reception frequency bands are slightly shifted from each other, and due to external factors such as a shift of the reception frequency band based on a process error and the influence of the casing of the device on the radio wave. You may make it absorb the shift | offset | difference of a receiving frequency band by selecting suitably the MEMS antenna utilized among these several MEMS antennas 10, 10a-10z.

It is a block diagram which shows the whole radio timepiece of embodiment of this invention. It is a perspective view which shows the structure of the MEMS antenna of embodiment of this invention. It is a longitudinal cross-sectional view of the MEMS antenna of FIG. It is a circuit diagram which shows the electrical structure of the MEMS antenna of FIG. The graph showing the frequency characteristic of a MEMS antenna and the conventional coil type | mold antenna is shown. It is a longitudinal cross-sectional view which shows the 1st modification of a MEMS antenna. It is a circuit diagram which shows the electrical connection structure of the MEMS antenna of a 1st modification. The 2nd modification of a MEMS antenna is shown, (a) is a longitudinal cross-sectional view, (b) is a top view of a substrate surface.

Explanation of symbols

1 radio time clock 10, 10a-10z, 10A, 10E MEMS antenna (antenna part)
DESCRIPTION OF SYMBOLS 11 Board | substrate 12 Beam part 13 Magnetic body 14 Permanent magnet 15 Spacer 16 Electrode (1st electrode)
17 electrode (second electrode)
20 Cover plate 21 Electrode (third electrode)
25 Coil magnet Cv, Cv2 Variable capacity 100 Radio wave receiver (receiver)
101 amplifier 102 detector (demodulator)
103 Microcomputer 104 Time display 105 Time counter 108 Switch circuit

Claims (6)

A radio wave having a characteristic that vibrates at a predetermined natural frequency and that is displaced by receiving an external magnetic field, and a conversion unit that converts the motion of the vibrator into an electric signal, and having a frequency band that resonates the vibrator When a signal arrives, the vibrating body resonates due to the magnetic field component of the radio signal, and the resonance is converted into an electric signal by the conversion means, so that the radio signal in the frequency band is converted into an electric signal and captured. An antenna device including an antenna unit,
An antenna device, wherein a plurality of the antenna units are provided with different natural frequencies of the vibrating body.   The antenna device according to claim 1, wherein the plurality of antenna units are formed on a one-chip substrate.   2. The antenna device according to claim 1, further comprising switch means for selectively sending an electrical signal from any one of the plurality of antenna units to a subsequent stage. An antenna device according to claim 3,
An amplifier for amplifying an electrical signal sent from the antenna device via the switch means;
A demodulator that performs demodulation processing on the signal amplified by the amplifier;
A receiving apparatus comprising:   5. The receiving device according to claim 4, wherein the antenna device, the amplifier, and the demodulator are formed on a one-chip semiconductor substrate.   A radio timepiece which receives a standard radio wave by the receiving device according to claim 4, demodulates a time code included in the standard radio wave, and corrects the time based on the time code.

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