JP2007139473A - Radio wave receiving device and radio controlled timepiece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly sensitive radio wave receiving device and a radio controlled timepiece which is high in precision and small in signal loss in the demodulation stage without necessitating fine adjustment of frequency selectivity Q in the production process and independent to the material of mounting equipment. <P>SOLUTION: The radio receiver 10 comprises: a pulse generator 1; an MI element 20; a magnetism collector 21; an antenna part 2 for detecting the external radio wave as magnetic variation and responding electrically; an amplifying part 30 for amplifying the output of antenna part 2; an A/D converter part 31 for converting the analogue signal into digital signal; and a digital filter part 3 for taking out the desirable frequency component. At the latter stage of the radio receiver 10, a clock functional part 9 is arranged for controlling a long hand 5A and short hand 5B of a wrist watch 5 based on the output of the digital filter part 3. The clock functional part 9 comprises: a signal processing part 4 for converting the digital signal into the output signal corresponding to the time information; and a hand driving part 8 for driving the long hand 5A and the short hand 5B based on the output signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radio wave receiving apparatus and a radio wave correction timepiece which are constituted by a magnetoresistive element and a digital filter circuit.

  As a conventional technique, a radio wave receiver for a radio timepiece is known. There are 40 kHz and 60 kHz long wave standard radio waves, which are each subjected to 1 Hz AM modulation. By demodulating the AM modulated wave, time information in Japan standard time can be obtained. As a receiver for demodulating an AM-modulated wave, there is a small-sized radio-wave clock receiving LSI (Large Scale Integrated circuit) that can be mounted on a wristwatch or the like (for example, Non-Patent Document 1).

  This radio clock receiving LSI has a method of rectifying and integrating a radio signal, a coiled antenna, an amplifying unit for amplifying a received radio wave, a crystal filter for extracting only a signal of a desired frequency, It has a rectifier for signal rectification and an integrator for integrating the signal.

This radio-controlled timepiece LSI has an auto gain control function and a wide voltage dynamic range. Further, the power consumption is 50 μA and the minimum input sensitivity is 1 μVrms, realizing high sensitivity and low power consumption.
Masataka Kinoshita, “Radio Clock Receiver LSI”, Micromechatronics, Japan, The Japan Society of Clock Studies, May 1999, Vol. 43, No. 4, P63-69

  However, according to the conventional radio-controlled timepiece LSI, all circuits are composed of analog circuits, so that signal loss occurs in the crystal filter and the like, and temperature characteristics and aging changes in physical properties occur in each component in the apparatus. There is a problem. Further, the antenna used in the apparatus is a coil type, and the frequency selectivity Q is determined in relation to the LCR of the entire apparatus. Therefore, fine adjustment of Q is required when manufacturing the apparatus. In addition, since the sensitivity of the coil type antenna is remarkably lowered in the vicinity of the metal, the material used for the mounted electronic device is restricted.

  Accordingly, an object of the present invention is to provide a highly sensitive radio wave receiving apparatus that is highly accurate with little signal loss in the radio wave demodulating stage, does not require fine adjustment of the frequency selectivity Q in the manufacturing process, and does not depend on the material of the mounted equipment. The purpose is to provide a radio-controlled watch.

    In order to achieve the above-described object, the present invention provides a magnetic detection unit including an MI (Magneto-Impedance) element that detects an external magnetic field generated by a standard time radio wave, and the MI element in a direction in which the MI element responds to the external magnetic field. An antenna unit that is installed in a symmetric structure near both ends of the element and has a magnetic flux collector made of a high permeability material having a property of collecting a frequency component of a certain frequency or less with respect to the external magnetic field, and the external magnetic field A digital bandpass filter that extracts a frequency component of a desired band from an electrical response of the antenna unit generated based on the signal, a rectifier that converts an AC signal into a DC signal, and a digital low-pass filter that cuts a signal of a desired frequency or higher And a digital filter unit that extracts a desired frequency component, and a waveform shaping unit that shapes a signal waveform; Providing a radio wave receiving apparatus including a signal processing unit for conversion into an output signal corresponding to the time information of digital signals outputted from the Rufiruta unit.

  According to such a configuration, the apparatus has higher sensitivity than the case of the MI element alone due to the magnetic collection effect of the high magnetic permeability material. Further, since the high magnetic permeability material is insensitive to a frequency component above a certain level, the received radio wave does not contain a high frequency component, and there is no need for anti-aliasing in the digital filter. In addition, the use of the MI element instead of the coiled antenna eliminates the need for fine adjustment of the frequency selectivity Q of the antenna at the time of manufacture, and at the same time near the metal where the sensitivity of the coiled antenna is significantly reduced. Can be received. In addition, by using a digital circuit for processing received radio waves, signal loss, degradation of the device itself, and the like can be suppressed. In addition, it is possible to output a signal suitable for mounting on a radio-controlled timepiece or the like.

  Further, in order to achieve the above object, the present invention provides a magnetic detection unit including an MI (Magneto-Impedance) element that detects an external magnetic field by a standard time radio wave, and a direction in which the MI element reacts to the external magnetic field, An antenna unit having a magnetism collecting unit made of a high permeability material which is installed in a symmetric structure near both ends of the MI element and has a property of collecting a frequency component of a certain frequency or less with respect to the external magnetic field; A digital bandpass filter that extracts a frequency component of a desired band from the electrical response of the antenna unit that is generated based on a magnetic field, a rectifier that converts an AC signal into a DC signal, and a digital that cuts a signal above a desired frequency A digital filter unit that includes a low-pass filter and a waveform shaping unit that shapes a signal waveform, and extracts a desired frequency component; Radio wave correction including a signal processing unit that converts a digital signal output from the digital filter unit into an output signal corresponding to time information, and a needle driving unit that drives a long hand and a short hand based on the output signal of the signal processing unit Provide a watch.

  According to such a configuration, the sensitivity is high, fine adjustment of the frequency selectivity Q can be omitted at the time of manufacture, a metal case can be used, and loss in the signal processing stage can be avoided, so it can handle weak radio waves. In addition, since it is possible to prevent aging of the apparatus, it is possible to configure a long-life radio wave receiving apparatus and radio wave correction watch.

  Further, the high magnetic permeability material may be configured using cobalt amorphous having a property of collecting a frequency component of 100 kHz or less with respect to the external magnetic field.

  According to the present invention, a high-sensitivity radio wave receiver and radio wave correction watch that is highly accurate without signal loss in the radio wave demodulation stage, does not require fine adjustment of the frequency selectivity Q in the manufacturing process, and does not depend on the material of the mounted device. Can be configured.

  Embodiments of a radio wave receiver according to the present invention will be described below in detail with reference to the drawings.

[First Embodiment]
FIG. 1A is a schematic configuration diagram of a radio wave receiving apparatus according to the first embodiment of the present invention. FIG. 1B is a detailed view of the digital filter unit in FIG.

(Configuration of radio wave receiver)
This radio wave receiver 10 includes a pulse generator 1 that generates a pulse voltage, an MI element 20 and a magnetic collector 21, an antenna unit 2 that detects an external radio wave as a change in magnetic field and electrically responds, and an antenna unit 2, an A / D converter 31 that converts the amplified analog signal into a digital signal, a digital filter unit 3 that extracts a desired frequency component from the output of the A / D converter 31, The signal processing unit 4 converts the output of the digital filter unit 3 into a desired output corresponding to an electronic device in which the radio wave receiving device 10 is mounted.

  The digital filter unit 3 includes a digital bandpass filter 32 that separates carriers of 40 kHz and 60 kHz, a digital rectifier unit 33 that converts an AC signal into a DC signal, a digital lowpass filter 34 that extracts an 1 Hz AM modulation signal, And a digital waveform shaping unit 35 for extracting a rectangular wave pulse.

  The digital band-pass filter 32 and the digital low-pass filter 34 are configured in an FIR (Finite Impulse Response) filter or an IIR (Infinite Impulse Response) filter format.

(Configuration of antenna part)
FIG. 2 is a plan view showing the configuration of the antenna unit according to the first embodiment of the present invention.

  The antenna unit 2 is configured by using an MI element 20 that electrically responds to an external magnetic field as an impedance change and a cobalt amorphous ribbon, and is provided at both ends of the MI element 20 so as to collect the external magnetic field. It has a magnetic part 21, a Si substrate 22 that serves as a base for the MI element 20 and the magnetic collecting part 21, and a sealing resin 23 for sealing and fixing the MI element 20, the magnetic collecting part 21 and the Si substrate 22. . The sealing resin 23 is not necessarily transparent, but a transparent one is used to explain the internal structure.

  FIG. 3A is a plan view showing details of the antenna unit according to the first embodiment of the present invention. FIG.3 (b) is sectional drawing in the AA part of Fig.3 (a).

As shown in FIGS. 3A and 3B, the MI element 20 includes a high-permeability magnetic film 200 that is formed in a zigzag pattern on the surface of the Si substrate 22, and a high-permeability magnetic film 200 externally. And an electrode 201 made of aluminum (Al) for electrically connecting the high magnetic permeability magnetic films 200 to each other. Further, MI device 20 and the magnetism collecting part 21 is electrically insulated by a passivation film 202 by the SiO _2.

  The MI element 20 is provided so that the distance D1 between the high permeability magnetic film 200 and the magnetism collecting portion 21 is 2.0 mm or less. Further, a step portion is formed on the Si substrate 22 so that the central axis deviation D2 in the thickness direction of the high magnetic permeability magnetic film 200 and the magnetism collecting portion 21 is 0 mm.

  The high magnetic permeability magnetic film 200 has a thickness of about 1 μm. The magnetism collecting part 21 has a shape having a length of 12.5 mm, a width of 1.2 mm, and a thickness of 20 μm. The passivation film 202 has a thickness of about 0.5 μm.

(Operation of radio wave receiver)
The operation of the radio wave receiving apparatus according to the embodiment of the present invention will be described below with reference to FIGS.

  In the antenna unit 21, the magnetic flux collectors 21 provided at both ends of the MI element 20 collect magnetic flux so as to penetrate the MI element 20 from one outer end of the magnetic flux collector 21 to the other outer end. The MI element 20 reacts to the magnetic flux collected in the longitudinal direction, and the impedance changes. The antenna unit 21 reacts similarly with respect to radio waves that are electromagnetic waves, and the impedance changes.

  FIG. 4 is a graph showing the characteristics depending on the material of the magnetic flux collector according to the first embodiment of the present invention.

  When the magnetic flux collecting unit 21 uses cobalt amorphous, the magnetic permeability is remarkably lowered with respect to radio waves having a frequency of 100 kHz or more. As a result, the magnetic flux density penetrating the MI element 20 decreases, and the antenna unit 2 apparently becomes insensitive to radio waves of 100 kHz or higher.

  The output of the pulse generation unit 1 changes based on the impedance change of the antenna unit 21 described above, and is processed by the amplification unit 30 and the A / D conversion unit 31 and then input to the digital filter unit 3. The digital filter unit 3 outputs only a frequency signal in a desired band to the signal processing unit 4.

(Effects of the first embodiment)
According to the above-described embodiment, because of the characteristics of the cobalt amorphous used in the magnetism collecting unit 21, it becomes insensitive to radio waves having a frequency of 100 kHz or more and can be used as a low-pass filter without signal attenuation. Therefore, it can be said that the digital filter unit 3 can be simplified and the power consumption can be reduced. Further, unlike the case where a low-pass filter is used in the subsequent stage of the antenna unit 2 instead of having the magnetism collecting unit 21, it is possible to use a high frequency or pulse rectangular wave for a signal input from the pulse generation unit 1 to the antenna unit 2. As a result of the signal processing using the high frequency or pulse rectangular wave, the radio wave receiving device 10 can be configured with high sensitivity. Further, the sensitivity of the antenna unit 2 as a whole is improved by the magnetic collecting effect of cobalt amorphous.

  In addition, by using a cobalt amorphous ribbon that can be flexibly deformed for the magnetism collecting section 21, it becomes possible to match the shape of the case of the mounted device, and there are fewer restrictions on the mounting method and it can be mounted on small electronic devices. Become. In addition, since cobalt amorphous has a flat frequency characteristic without frequency selectivity Q at 100 kHz or less, there is no need to consider the influence of a change in Q in the vicinity of the metal, and an electronic device using a metal case, etc. It becomes possible to mount on.

Further, since the digital filter unit 3 is used as a signal processing filter, signal loss due to filtering is eliminated. Further, it is 0 to _{V F} during rectification in the rectifier unit 33. In addition, since the digital filter unit 3 has no temperature characteristics and does not change with time, stable operation can be guaranteed. In addition, since the digital filter unit 3 controls the frequency selectivity Q on software, it is possible to realize highly accurate filtering and tuning. For this reason, the signal processing unit 4 in the subsequent stage can perform signal processing using a highly accurate signal that is not affected by temperature characteristics or aging.

  The antenna unit 2 may be configured using ferrite for the magnetism collecting unit 21. As shown in FIG. 4, since ferrite has a flat frequency characteristic without frequency selectivity Q at 1 MHz or less, radio waves can be received in a wider frequency band than cobalt amorphous. In this embodiment, the reception of radio waves of 40 kHz and 60 kHz has been described. However, it is possible to detect an external magnetic field having a desired frequency by adjusting the filtering of the digital filter using ferrite. For example, it can be used as a receiver for an RFID tag that uses radio waves of 250 kHz, a receiver for a keyless entry system such as an automobile that uses radio waves of 125 kHz and 315 kHz, and an AM receiver that receives radio waves having a frequency of 1 MHz or less. .

[Second Embodiment]

  FIG. 5 shows a wristwatch-type radio-controlled timepiece according to the second embodiment of the present invention, FIG. 5 (a) is a plan view showing an external configuration, and FIG. 5 (b) is a plane showing an internal configuration. FIG. In the following description, parts having the same configuration and function as those of the first embodiment are denoted by common reference numerals.

(Watch configuration)
As shown in FIG. 5 (a), the wristwatch 5 houses a long hand 5A indicating time in minutes, a short hand 5B indicating time in time, a dial 5C on which the time is stamped, and each component. A wristwatch case 6 and an adjusting unit 7 for manually adjusting the time are provided.

  FIG. 5B is an internal configuration diagram with the dial 5C removed. As shown in FIG. 5B, the wristwatch 5 includes a pulse generating unit 1, an antenna unit 2, an amplifying unit 30, and an A / D. It has a timepiece function unit 9 including a radio wave receiver 10 including a conversion unit 31, a digital filter unit 3, a signal processing unit 4, and a hand drive unit 8 that controls the long hand 5 </ b> A and the short hand 5 </ b> B. The antenna unit 2 includes an MI element 20 and a magnetism collecting unit 21 made of cobalt amorphous deformed according to the wristwatch case 6.

  FIG. 6A is a schematic configuration diagram of a wristwatch-type radio-controlled timepiece according to the second embodiment of the present invention. FIG. 6B is a detailed view of the timepiece function unit in FIG.

  As shown in FIG. 6 (a), the radio wave receiver 10 includes a pulse generator 1 that generates a pulse voltage, an MI element 20, and a magnet collector 21, and detects an external radio wave as a change in magnetic field and electrically The antenna unit 2 that responds, the amplification unit 30 that amplifies the output of the antenna unit 2, the A / D conversion unit 31 that converts the amplified analog signal into a digital signal, and a desired output from the output of the A / D conversion unit 31 And a digital filter unit 3 for extracting frequency components. A timepiece function unit 9 for controlling the long hand 5 </ b> A and the short hand 5 </ b> B of the wristwatch 5 based on the output of the digital filter unit 3 is installed at the subsequent stage of the radio wave receiver 10.

  As shown in FIG. 6B, the clock function unit 9 includes a signal processing unit 4 that converts a digital signal corresponding to the standard radio wave output from the digital filter unit 3 into an output signal corresponding to time information, Based on the output signal of the signal processing unit 4, it has a long needle 5A and a needle driving unit 8 that drives the short hand 5B.

(Watch operation)
The operation of the wristwatch-type radio-controlled timepiece according to the second embodiment of the present invention will be described below with reference to FIGS.

  In the antenna unit 21, the magnetic flux collectors 21 provided at both ends of the MI element 20 collect magnetic flux so as to penetrate the MI element 20 from one outer end of the magnetic flux collector 21 to the other outer end. The MI element 20 reacts to the magnetic flux collected in the longitudinal direction, and the impedance changes. The antenna unit 21 reacts similarly with respect to 40 kHz and 60 kHz electromagnetic waves, which are standard radio waves for a radio timepiece, and the impedance changes.

  Since the magnetism collecting unit 21 uses cobalt amorphous, the magnetic permeability is remarkably lowered with respect to radio waves having a frequency of 100 kHz or more. As a result, the magnetic flux density penetrating the MI element 20 decreases, and the antenna unit 2 apparently becomes insensitive to radio waves of 100 kHz or higher.

  The output of the pulse generator 1 changes based on the impedance change of the antenna unit 21 and is input to the digital filter unit 3. The digital filter unit 3 separates the carriers having the frequencies of 40 kHz and 60 kHz, demodulates and extracts the 1 Hz AM modulation signal, and outputs the result to the timepiece function unit 9. The signal processing unit 4 of the timepiece function unit 9 converts the input from the digital filter unit 3 into a signal corresponding to the hand drive unit 8 and outputs it. The hand drive unit 8 drives the long hand 5A and the short hand 5B to an accurate time position on the dial 5C according to the output of the signal processing unit 4, and corrects the time display.

(Effect of the second embodiment)
According to the second embodiment described above, since the characteristics of the cobalt amorphous used in the magnetism collecting unit 21 are insensitive to radio waves having a frequency of 100 kHz or more and can be used as a low-pass filter without signal attenuation, the digital filter unit 3 Therefore, it is not necessary to perform anti-aliasing for high-frequency radio waves, simplifying the digital filter unit 3 and reducing power consumption can be said to be an excellent configuration. Moreover, it can be said that the filtering which cuts 100 kHz or more is a filtering suitable for the standard time wave of Japan standard time using the frequency of 40 kHz and 60 kHz.

  Further, unlike the case where a low-pass filter is used in the subsequent stage of the antenna unit 2 instead of having the magnetism collecting unit 21, a pulse rectangular wave can be used as a signal input from the pulse generating unit 1 to the antenna unit 2. As a result of signal processing using the pulse rectangular wave, the radio wave receiver 10 can be configured with high sensitivity. In addition, since the radio wave receiver 10 can be configured without using a large-scale part by configuring without using the high-frequency generator, the design constraints of the wristwatch 5 are reduced.

  Further, due to the cobalt amorphous magnetic collecting effect, when the distance between the MI element 20 and the magnetic collecting part 21 is 30 μm and the axial deviation in the thickness direction is 0 mm, the antenna part 2 as a whole is compared with the case where the magnetic collecting part 21 is not installed. Therefore, the wristwatch 5 can receive time information in a wider range.

  In addition, since a cobalt amorphous ribbon that can be flexibly deformed is used for the magnetism collecting portion 21, it becomes possible to install the watch case 6 in conformity with the shape, so that the design constraints of the watch 5 are reduced. In addition, since cobalt amorphous has a flat frequency characteristic without frequency selectivity Q at 100 kHz or less, it is not necessary to consider the influence of a change in Q in the vicinity of the metal. It can be used, and there are no restrictions on material selection. Further, since it is not necessary to finely adjust the frequency selectivity Q after the radio wave receiver 10 is installed, the process can be simplified at the time of manufacturing, and productivity is improved.

  In this embodiment, the reception of radio waves of 40 kHz and 60 kHz has been described, but it is also possible to detect a DC magnetic field and a low frequency magnetic field by adjusting the filtering of the digital filter. For example, a measuring instrument that detects radio waves and magnetic fields based on movements of several Hz such as indirect movement of the human body and heartbeat, such as a compass that detects constant magnetic fields, metal detectors in the ground, etc. Can also be applied. For the above applications, the apparatus can be configured with an equivalent scale and can be mounted on a small electronic device such as a wristwatch.

(A) is a schematic block diagram of the electromagnetic wave receiver regarding the 1st Embodiment of this invention. FIG. 2B is a detailed view of the digital filter unit in FIG. It is a top view which shows the structure of the antenna part which concerns on the 1st Embodiment of this invention. (A) is a top view which shows the detail of the antenna part which concerns on the 1st Embodiment of this invention. (B) is sectional drawing in the AA part of Fig.3 (a). It is a graph which shows the characteristic by the material of the magnetic flux collection part which concerns on the 1st Embodiment of this invention. FIG. 2 shows a wristwatch-type radio-controlled timepiece according to a second embodiment of the present invention, wherein (a) is a plan view showing an external configuration, and (b) is a plan view showing an internal configuration. (A) is a schematic block diagram of the wristwatch-type radio-controlled timepiece according to the second embodiment of the present invention. FIG. 7B is a detailed view of the timepiece function unit in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pulse generation part, 2 ... Antenna part, 3 ... Digital filter part, 4 ... Signal processing part, 5A ... Long hand, 5B ... Short hand, 5C ... Dial, 5 ... Wristwatch, 6 ... Wristwatch case, 7 ... Adjustment part, DESCRIPTION OF SYMBOLS 8 ... Hand drive part, 9 ... Clock function part, 10 ... Radio wave receiving apparatus, 20 ... MI element, 21 ... Antenna part, 21 ... Magnetic flux collecting part, 22 ... Si substrate, 23 ... Sealing resin, 30 ... Amplifying part, DESCRIPTION OF SYMBOLS 31 ... A / D conversion part, 32 ... Band pass filter, 33 ... Rectification part, 34 ... Low pass filter, 35 ... Waveform shaping part, 200 ... High magnetic permeability magnetic film, 201 ... Electrode, 202 ... Passivation film

Claims (4)

A magnetic detection unit comprising an MI (Magneto-Impedance) element that detects an external magnetic field by a standard time radio wave, and a symmetrical structure close to both ends of the MI element along a direction in which the MI element reacts to the external magnetic field And an antenna portion having a magnetic flux collecting portion made of a high permeability material having a property of collecting a frequency component of a certain frequency or less with respect to the external magnetic field,
A digital bandpass filter that extracts a frequency component in a desired band from the electrical response of the antenna unit that is generated based on the external magnetic field, a rectifier that converts an AC signal into a DC signal, and a signal that exceeds the desired frequency Including a digital low-pass filter and a waveform shaping unit that shapes a signal waveform, and a digital filter unit that extracts a desired frequency component;
A radio wave receiving apparatus comprising: a signal processing unit that converts a digital signal output from the digital filter unit into an output signal corresponding to time information.   The radio wave receiver according to claim 1, wherein the high magnetic permeability material is made of cobalt amorphous having a property of collecting a frequency component of 100 kHz or less with respect to the external magnetic field. A magnetic detection unit comprising an MI (Magneto-Impedance) element that detects an external magnetic field by a standard time radio wave, and a symmetrical structure close to both ends of the MI element along a direction in which the MI element reacts to the external magnetic field And an antenna portion having a magnetic flux collecting portion made of a high permeability material having a property of collecting a frequency component of a certain frequency or less with respect to the external magnetic field,
A digital bandpass filter that extracts a frequency component in a desired band from the electrical response of the antenna unit that is generated based on the external magnetic field, a rectifier that converts an AC signal into a DC signal, and a signal that exceeds the desired frequency Including a digital low-pass filter and a waveform shaping unit that shapes a signal waveform, and a digital filter unit that extracts a desired frequency component;
A signal processing unit that converts a digital signal output from the digital filter unit into an output signal corresponding to time information; and a needle driving unit that drives a long hand and a short hand based on the output signal of the signal processing unit. A radio-controlled watch featuring   The radio-controlled timepiece according to claim 3, wherein the high magnetic permeability material is made of cobalt amorphous having a property of collecting a frequency component of 100 kHz or less with respect to the external magnetic field.

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