JP2006242708A - Electronic timepiece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic timepiece having a high degree of design freedom using an integrated band-pass filter instead of a quartz filter. <P>SOLUTION: The electronic timepiece 100 comprises an antenna 1; a designation section 12 for designating one of a plurality of standard radio waves; a reference signal oscillation section 3; a clock section 7; a reference counter 4b for generating a reference frequency; a local oscillation frequency oscillation section 4d for outputting a local oscillation frequency; a main counter 4a for generating a main frequency; a phase comparison section 4c for controlling the local oscillation frequency oscillation section; a MIX section 9 for generating an intermediate frequency; and a BPF section 10 that has prescribed bandwidth and center frequency, is composed of an integrated circuit, and filters the intermediate frequency. In the electronic time keeping instrument 100, the intermediate frequency is set to a value within the range of the bandwidth, the center frequency is set to 1.0 kHz or higher and 10.0 kHz or smaller, and the reference frequency is set to 500 Hz or higher. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electronic timepiece capable of receiving a plurality of standard radio waves and correcting the time.

  There is known a radio timepiece that receives a time code transmitted by a standard radio wave and can correct a clock operation using accurate time information corresponding to the time code. For example, in Japan, standard radio waves of 40 kHz and 60 kHz are transmitted from two locations, and there are other countries and regions other than Japan that use standard radio waves of 68.5 kHz or 77.5 kHz.

  Therefore, an electronic timepiece that can handle only one standard radio wave cannot receive the standard radio wave in that area, especially when going abroad, and cannot correct the clock operation.

  Further, a source frequency (32768 Hz) for performing a clock operation is divided to generate a local oscillation frequency, and an intermediate frequency is generated by a so-called superheterodyne system that mixes a standard radio wave and a local oscillation frequency. There is a known radio timepiece that detects time information by filtering an intermediate frequency using a crystal filter circuit using a different crystal resonator (see, for example, Patent Document 1).

  However, it is necessary to generate a local oscillation frequency corresponding to a plurality of standard radio waves having different frequencies by dividing the source oscillation (32768 Hz), and the oscillation frequency of the crystal resonator is limited. When designing an electronic timepiece, the IF frequency selection range of the circuit is limited, and the intermediate frequency corresponding to all standard radio waves must be set within the specified error range of the IF frequency of the crystal filter circuit. The degree of freedom in was very narrow.

Japanese Patent Laid-Open No. 6-214054 (FIG. 1)

  Therefore, an object of the present invention is to provide an electronic timepiece that can solve the above-described problems.

  Another object of the present invention is to provide an electronic timepiece that can be reduced in size and cost by using an integrated band-pass filter circuit instead of a quartz filter and has a high frequency of design freedom. And

  It is another object of the present invention to provide an electronic timepiece having a higher degree of design freedom that can adjust the center frequency of a bandpass filter circuit.

In order to solve the above-described problems, an electronic timepiece according to the present invention includes an antenna for receiving a plurality of standard radio waves, a designation unit for designating one of the plurality of standard radio waves, and a reference signal oscillation for generating a reference signal Unit, a clock unit that performs a clock operation based on the reference signal, a reference counter that divides the reference signal to generate a reference frequency according to the specified standard radio wave, and a standard specified based on the reference frequency The local oscillation frequency output unit that outputs the local oscillation frequency according to the radio wave, the main counter that divides the local oscillation frequency to generate the main frequency, the reference frequency and the main frequency are compared, and the local oscillation frequency oscillation unit A phase comparison unit to be controlled, a MIX unit that generates an intermediate frequency in accordance with a designated standard radio wave by mixing a designated standard radio wave and a local oscillation frequency, and a predetermined bandwidth. And heart Has a wavenumber, and a BPF unit for filtering the intermediate frequency,
All of the plurality of standard radio waves are set so that the intermediate frequency is within the range of the bandwidth, the center frequency is 1.0 kHz or more and 10.0 kHz or less, and the reference frequency is 500 Hz or more.

  In the electronic timepiece according to the invention, it is preferable that the plurality of standard radio waves include at least two of 40 kHz, 60 kHz, 68.5 kHz, and 77.5 kHz.

  Furthermore, in the electronic timepiece according to the invention, the frequency of the reference signal is preferably 32768 Hz. The oscillator is made common by using the source oscillation for the clock operation.

  Furthermore, it is preferable that the electronic timepiece according to the invention further includes a control unit that acquires time information by detecting the intermediate frequency that has passed through the BPF unit, and corrects the timepiece operation of the timepiece unit based on the time information.

  Furthermore, it is preferable that the electronic timepiece according to the present invention further includes a center frequency adjusting unit for finely adjusting or adjusting the center frequency. An integrated BPF part capable of fine adjustment or adjustment of the center frequency was used for intermediate frequency filtering.

  Furthermore, in the electronic timepiece according to the invention, the center frequency is preferably 1950 Hz, 2134 Hz or 2325 Hz.

  According to the present invention, it is possible to provide an electronic timepiece that can receive different standard radio waves used in a plurality of countries or a plurality of regions and has a high degree of design freedom.

  In addition, according to the present invention, it is possible to provide an electronic timepiece that does not require a quartz filter, can be reduced in size and cost, and has a high degree of design freedom.

  In addition, according to the present invention, it is possible to adjust the center frequency of the bandpass filter circuit by using an integrated bandpass filter circuit instead of the crystal filter, so that an electronic timepiece having a higher degree of design freedom is provided. It became possible to provide.

  An electronic timepiece with a radio wave receiving function according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing a schematic configuration of an electronic timepiece 100 with a radio wave receiving function according to the present invention.

  As shown in FIG. 1, an electronic timepiece 100 with a radio wave reception function includes an antenna 1 that receives a standard radio wave as a radio signal, a tuning unit 2 that tunes to the frequency of the radio signal that the antenna 1 receives, and a crystal resonator that oscillates at 32768 Hz. The oscillation circuit 3 that oscillates by 3a, the local oscillation circuit 4 that outputs the local oscillation frequency by the PLL method with reference to the 32768 Hz frequency from the oscillation circuit 3, the data D that determines the tuning frequency, and the counter of the local oscillation circuit 4 are set. A channel selection unit 5 that outputs data Dr and Dm, a control unit 6 that outputs a command signal C that determines which standard radio wave is received according to an instruction signal from the operation unit 12, and a frequency of 32768 Hz from the oscillation circuit 3 The clock unit 7 that performs the clock operation, the display unit 8 that displays the time based on the data from the clock unit 7, and the received standard radio wave A MIX circuit 9 that generates an intermediate frequency by mixing the local oscillation frequency output from the local oscillation circuit 4, a bandpass filter (BPF) circuit 10 that filters the intermediate frequency (removal and / or amplification of noise components), and a BPF circuit Is composed of a detection circuit 11 for detecting an intermediate frequency from, an operation unit 12 including buttons, switches, and the like.

  The local oscillation circuit 4 divides the frequency of 32768 Hz from the oscillation circuit 3 according to the data Dr from the channel selection unit 5 and outputs the reference frequency Fr, the oscillation unit 4 d that oscillates the local frequency, and the channel selection unit 5 The main counter 4a that divides the local oscillation frequency from the oscillation unit 4d according to the data Dm and outputs the main frequency Fm, the phase comparison circuit 4c that outputs the control signal Ss or Sb to the oscillation unit 4d, and the like.

  In the phase comparison circuit 4c, the reference frequency Fr and the main frequency Fm are compared, and if Fm is greater than Fr, the control signal Ss is output to the oscillation unit 4d to control the local frequency to be small, and Fm is When the frequency is smaller than Fr, the control signal Sb is output to the oscillation unit 4d to control the local oscillation frequency to be increased. That is, the phase comparison circuit 4c performs PLL control so that Fr and Fm have the same frequency.

  The operation of the timepiece of the electronic timepiece with radio wave receiving function 100 according to the present invention will be described.

  As described above, since a plurality of standard radio waves exist, the user first designates which standard radio wave of 40 kHz, 60 kHz, 68.5 kHz, and 77.5 kHz to use by using the operation unit 12. To do. The four standard radio waves described above are examples, and the present invention can be applied to other standard radio waves. In addition, the standard radio waves corresponding to a specific electronic timepiece do not have to be all four, and may be standard radio waves having at least two different frequencies.

  Next, the control unit 6 outputs to the channel selection unit 5 a command signal C indicating that the standard radio wave designated by the operation unit 12 is received.

  Next, the tuning unit 5 outputs data D corresponding to the tuning frequency corresponding to the command signal C to the tuning unit 2. At the same time, the channel selection unit 5 outputs data Dm and Dr corresponding to the tuning frequency corresponding to the command signal C to the main counter 4a and the reference counter 4b of the local oscillation circuit 4, respectively.

  The tuning unit 2 determines the tuning frequency of the antenna 1 according to the data D received from the channel selection unit 5.

  The main counter 4a sets the count number to the data Dm received from the channel selection unit 5, thereby outputting the main frequency Fm with the local oscillation frequency from the oscillation unit 4d being 1 / Dm. In the reference counter 4b, the count number is set in the data Dr received from the channel selection unit 5, thereby outputting the reference frequency Fr obtained by setting the frequency of 32768 Hz from the oscillation circuit 3 to 1 / Dr. The phase comparison circuit 4c compares Fm and Fr, and controls the oscillation unit 4d using the control signals Ss and Sb so that Fm and Fr have the same frequency. Therefore, the local oscillation circuit 4 outputs a local oscillation frequency obtained by frequency-dividing the clock source vibration (32768 Hz) in accordance with the data Dm and Dr received from the channel selection unit 5.

  Next, the MIX circuit 9 receives the standard radio wave received from the antenna 1 tuned to the designated standard radio wave and the local oscillation frequency from the local oscillation circuit 4. The input standard radio wave and local oscillation frequency are mixed by the MIX circuit 9, and the frequency difference between both signals is converted into an intermediate frequency. The intermediate frequency is filtered by the BPF circuit 10 and output to the detection circuit 11. That is, since a superheterodyne system that amplifies a signal using two frequencies, a high frequency and an intermediate frequency, is employed, it operates stably.

  Next, the detection circuit 11 detects the filtered intermediate frequency to generate a detection signal, and outputs the detection signal to the control unit 6.

  Next, the control unit 6 converts the received detection signal into time information. The time information and the time of the clock unit 7 are compared. If they do not match, the time of the clock unit 7 is corrected to the time information corresponding to the received detection signal. In this way, the time of the clock unit 7 matches the time information corresponding to the time code transmitted by the standard radio wave.

  The correction of the time using the standard radio wave described above is performed a predetermined number of times (for example, twice a day) at a predetermined time. When the time is not corrected by the standard radio wave, the clock unit 7 operates as a normal clock based on the source oscillation from the oscillation circuit 3.

  FIG. 2 is a diagram illustrating an example of frequency characteristics of the BPF circuit 10.

  The BPF circuit 10 is configured as a circuit integrated as a CMOS IC, and does not use a crystal resonator.

As shown in FIG. 2, the frequency characteristic of the BPF circuit 10 has a center frequency ω ₀ and a bandwidth for obtaining a predetermined filter gain. In the electronic timepiece 100 with a radio wave reception function according to the present invention, it is preferable to set the bandwidth Δf / 2 of the BPF circuit 10 to 5 Hz or more and 30 Hz or less. This is because if Δf / 2 is less than 5 Hz, the modulated wave in which the time code is modulated is attenuated, and if Δf / 2 is greater than 30 Hz, the passage of noise increases. Note that if the intermediate frequency falls within the bandwidth Δf / 2, it is preferable that the filter characteristics of the BPF circuit 10 be limited to attenuation within approximately −1 dB.

For example, in the case of the center frequency ω ₀ = 2 kHz, assuming that the Q value is 40, Δf / 2 = 25 Hz, which satisfies the above condition.

Therefore, in order to accurately demodulate the time information from the standard radio wave in the electronic timepiece 100 with the radio wave receiving function, the intermediate frequency generated by the MIX circuit 9 is set to Δf / 2 within the bandwidth of the BPF circuit 10. It is necessary to determine the center frequency ω ₀ of the BPF circuit 10 and the local frequency corresponding to each standard radio wave. In this case, the local oscillation frequency needs to be generated from a reference frequency obtained by dividing the source oscillation (32768 Hz) of the oscillation circuit 3 for clock operation in order to make the oscillation circuit common.

  FIG. 3 is a diagram for explaining the use range of the center frequency of the BPF circuit 10 used in the electronic timepiece 100 with a radio wave reception function according to the present invention.

In FIG. 3, the vertical axis indicates the center frequency ω ₀ (Hz) of the BPF circuit 10, and the horizontal axis indicates the reference frequency Fr (Hz) generated by the reference counter 4 b of the local oscillation circuit 4. Moreover, the black circle in Examples 1-3 and Comparative Examples 1-3 has shown the reference frequency when corresponding to each reference electromagnetic wave (40 kHz, 60 kHz, 68.5 kHz, and 77.5 kHz).

  FIG. 4 is a diagram illustrating specific numerical values in Examples 1 to 3 and Comparative Examples 1 to 3.

FIG. 4 shows the center frequency ω ₀ of the set BPF circuit 10, the reference radio wave, data Dr and Dr, the reference frequency Fr, the local frequency, and the intermediate frequency generated by the MIX circuit 9 for each of the examples and comparative examples. And the frequency difference between the center frequency ω ₀ and the intermediate frequency.

The center frequency ω ₀ , the reference radio wave, data Dr and Dr, the reference frequency Fr, the local frequency, the intermediate frequency, and the frequency difference will be described below using the third embodiment.

In the case of Example 3, the BPF circuit 10 was designed so as to have a center frequency ω ₀ of 2134 Hz, integrated, and incorporated into the electronic timepiece 100 with a radio wave reception function. Further, when up to about -1dB shall be acceptable in BPF circuit 10, when the Q value of the BPF circuit 10 is 40, Delta] f / 2 but is about 25 Hz, the frequency difference when considering the variation of the center frequency omega ₀ It is considered that the noise component is satisfactorily removed and amplified until the absolute value is within 4 Hz.

  When the standard radio wave is 40 kHz, the tuning unit 2 is tuned to receive a received radio wave of 40 kHz, and the channel selection unit 5 outputs 45 and 52 as data Dr and Dm to the reference counter 4b and the main counter 4a. The reference counter 4b outputs 728.1778 Hz obtained by reducing the frequency of 32768 Hz from the oscillation circuit 3 to 1/45 as the reference frequency Fr. Further, the phase comparison circuit 4c operates so that the main counter 4a makes the main frequency Fm obtained by reducing the frequency of the oscillating unit 4d to 1/52 to be the same as Fr. A lower frequency of 728.1778 × 52 = 37865.24 Hz is output as the local oscillation frequency. Therefore, the intermediate frequency is (40000−728.1778 × 52) = 2134.75556 Hz, and the frequency difference is 2134.755556-2134 = 0.75556 Hz. In this case, since the absolute value of the frequency difference is within 4 Hz, the intermediate frequency can be satisfactorily removed and amplified by the BPF circuit 10.

  When the standard radio wave is 60 kHz, the tuning unit 2 is tuned to receive a received radio wave of 60 kHz, and the channel selection unit 5 outputs 47 and 83 as data Dr and Dm to the reference counter 4b and the main counter 4a. The reference counter 4b outputs 697.1915 Hz obtained by reducing the frequency of 32768 Hz from the oscillation circuit 3 to 1/47 as the reference frequency Fr. Further, the phase comparison circuit 4c operates so that the main counter 4a has the same main frequency Fm that the frequency of the oscillating unit 4d is 1/83 as Fr, so that the oscillating unit 4d has the frequency of the received radio wave of 60 kHz. A lower frequency of 67.191915 × 83 = 57866.89 Hz is output as the local frequency. Therefore, the intermediate frequency (local frequency−reference radio wave) is 2133.10638 Hz, and the frequency difference (intermediate frequency−2134) is −0.89362 Hz. In this case, since the absolute value of the frequency difference is within 4 Hz, the intermediate frequency can be satisfactorily removed and amplified by the BPF circuit 10.

  When the standard radio wave is 68.5 kHz, the tuning unit 2 is tuned to receive a received radio wave of 68.5 kHz, and the channel selection unit 5 outputs 45 and 97 as data Dr and Dm to the reference counter 4 b and the main counter 4 a. . The reference counter 4b outputs 728.1778 Hz obtained by reducing the frequency of 32768 Hz from the oscillation circuit 3 to 1/45 as the reference frequency Fr. Further, the phase comparison circuit 4c operates so that the main counter 4a has the same main frequency Fm that the frequency of the oscillating unit 4d is 1/97 as Fr, so that the oscillating unit 4d is the frequency of the received radio wave 68. A frequency of 728.1778 × 97 = 70633.24 Hz higher than 5 kHz is output as the local frequency. Therefore, the intermediate frequency (local frequency−reference radio wave) is 2134.755556 Hz, and the frequency difference (intermediate frequency−2134) is 0.75556 Hz. In this case, since the absolute value of the frequency difference is within 4 Hz, the intermediate frequency can be satisfactorily removed and amplified by the BPF circuit 10.

  When the standard radio wave is 77.5 kHz, the tuning unit 2 is tuned to receive a received radio wave of 77.5 kHz, and the channel selection unit 5 outputs 40 and 92 as data Dr and Dm to the reference counter 4b and the main counter 4a. . The reference counter 4b outputs 819.2 Hz obtained by reducing the frequency of 32768 Hz from the oscillation circuit 3 to 1/40 as the reference frequency Fr. Further, the phase comparison circuit 4c operates so that the main counter 4a has the same main frequency Fm that the frequency of the oscillating unit 4d is 1/92 as Fr, so that the oscillating unit 4d is the frequency of the received radio wave. A frequency of 819.2 × 92 = 75366.4 Hz lower than 0.5 kHz is output as the local frequency. Therefore, the intermediate frequency (reference radio wave-local frequency) is 21333.60000 Hz, and the frequency difference (intermediate frequency -2134 is -0.40000 Hz. In this case, the absolute value of the frequency difference is within 4 Hz. The frequency can be satisfactorily removed and amplified by the BPF circuit 10.

Note that Example 1 (center frequency ω ₀ = 1950 Hz) and Example 2 (center frequency ω ₀ = 2325 Hz) can also correspond to each reference radio wave as shown in FIG. 3 and FIG. it can.

  As described above, the local frequency can be received whether it is higher or lower than the frequency of the standard radio wave to be received.

The reason for selecting the center frequency ω ₀ used in the electronic timepiece 100 with a radio wave reception function according to the present invention will be described below.

The center frequency ω ₀ and the reference frequency Fr corresponding to each reference radio wave in the three embodiments 1 to 3 described above are all included in the region (A) of FIG. Region (A) shows a range in which the center frequency ω ₀ is 1.0 kHz or more and 10 kHz or less and Fr is 500 Hz or more.

The region (B) is a region including a case where Fr is less than 500 Hz. When Fr is 500 Hz or less, the frequency division ratio from the source oscillation from the oscillation circuit 3 and the local oscillation frequency from the local oscillation circuit 4 becomes too large, and the comparison in the phase comparison circuit 4c becomes unstable, and as a result The stability of the emission frequency will deteriorate. Therefore, in the third comparative example shown in FIGS. 3 and 4 (in the case of the center frequency ω ₀ = 1722 Hz), the Fr is 306.243 Hz and less than 500 Hz when corresponding to the reference radio wave of 40 kHz. The electronic timepiece 100 is not suitable.

The region (C) is a region including a case where Fr is 500 Hz or more, but the center frequency ω ₀ is 10.0 kHz or more. The frequency characteristics of the integrated circuit inside the semiconductor cannot be expected to be high when a low current / low voltage design is performed. In particular, in a circuit that requires a high Q value, such as an intermediate frequency BPF circuit, a transistor circuit such as an OP amplifier used in the BPF circuit is required to have sufficient frequency characteristics with respect to the used frequency band. Generally, 20 times as much as the use frequency band of the BPF circuit is required. Therefore, in this embodiment, in order to realize low current consumption, the upper limit of the frequency characteristic of the OP amplifier or the like is 200 kHz, and the upper limit of the frequency band of the BPF circuit is 10 kHz or less.
Therefore, in the second comparative example shown in FIGS. 3 and 4 (in the case of the center frequency ω ₀ = 10036 Hz), the center frequency ω ₀ is higher than 10.0 kHz, and thus is not suitable as the electronic timepiece 100 with a radio wave reception function.

The region (D) is a region including a case where Fr is 500 Hz or more but the center frequency ω ₀ is less than 1.0 kHz. The BPF circuit 10 is mainly configured by a CR or the like. In order to lower the center frequency ω ₀ to less than 1.0 kHz, it is necessary to incorporate a capacitor having a large capacity. However, this requires a large space, and there is a problem that the integrated circuit becomes large. Therefore, in the comparative example 2 (in the case of the center frequency ω ₀ = 988 Hz), the center frequency ω ₀ is less than 1.0 kHz, which is not suitable as the electronic timepiece 100 with a radio wave reception function.

Therefore, in order to correct the clock operation satisfactorily in the electronic timepiece 100 with a radio wave reception function according to the present invention, it is further necessary that the center frequency ω ₀ is 1.0 kHz or more and 10 kHz or less and Fr is 500 Hz or more. is there.

  From the above, in order to perform time correction satisfactorily in the electronic timepiece with radio wave reception function 100 according to the present invention, it is necessary to satisfy at least the following four conditions.

Condition 1: For all the standard radio waves to be supported, the center frequency ω ₀ of the BPF circuit 10 and each standard radio wave so that the intermediate frequency generated by the MIX circuit 9 is within the bandwidth Δf / 2 of the BPF circuit 10. It is necessary to determine the local frequency corresponding to

  Condition 2: The local oscillation frequency output from the local oscillation circuit 4 needs to be generated from a reference frequency obtained by dividing the source oscillation (32768 Hz) of the oscillation circuit 3 for clock operation.

Condition 3: The center frequency ω ₀ of the BPF circuit 10 needs to be 1.0 kHz or more and 10 kHz or less.

  Condition 4: The standard frequency Fr in the local oscillation circuit 4 needs to be 500 Hz or more.

  Examples 1 to 3 shown in FIGS. 3 and 4 satisfy the above four conditions. In the electronic timepiece 100 with a radio wave reception function according to each example, standard radio waves (40 kHz, 60 kHz, 68. The clock operation can be corrected well for all of 5 kHz and 77.5 kHz. However, examples satisfying the above four conditions are not limited to the first to third embodiments.

  FIG. 5 is a diagram showing another BPF circuit 110 that can be used in the electronic timepiece 100 with a radio wave reception function according to the present invention.

  As shown in FIG. 5, the BPF circuit 110 includes a band pass filter unit 111 and a center frequency adjustment unit 112. The input terminals A and B to the center frequency adjustment unit 112 are connected to the control unit 6, the input terminal IN of the bandpass filter unit 111 is connected to the MIX circuit 9, and the output terminal OUT is connected to the detection circuit 11. Yes.

The center frequency adjustment unit 112 includes a plurality of transmission gates (TG) and capacitors. When a control input is made to the input terminal A or B, the TG is turned on / off, and the band corresponding to the capacitor connected to each TG is provided. The capacity of the pass filter unit 111 is increased / decreased so that the center frequency ω ₀ of the BPF circuit 110 can be shifted.

In the example of FIG. 5, the TG _A1 and TG _A2 are turned off by the control input to the input terminal A so that the center frequency ω ₀ of the BPF circuit 110 can be finely adjusted by f _A Hz. Further, the center frequency ω ₀ of the BPF circuit 110 is set to be adjusted by f _B Hz by turning off TG _B1 and TG _B2 by the control input to the input terminal B. In the present invention, fine adjustment means adjustment of about several Hz, and adjustment means adjustment from several tens of Hz to several hundreds of Hz.

  FIG. 6 is a diagram illustrating an operation example of the BPF circuit 110 illustrated in FIG.

In FIG. 6, the frequency characteristics when TG _A1 , TG _A2 , TG _B1 and TG _B2 are all turned ON by the control input to the input terminals A and B are set to 601, and TG _A1 and TG are controlled by the control input to the input terminal A. The frequency characteristic when only _A2 is turned off is 602, and the frequency characteristic when only TG _B1 and TG _B2 are turned off by the control input to the input terminal B is 603.

For example, in the first embodiment, the difference between the intermediate frequency when receiving a 40 kHz reference radio wave and the intermediate frequency when receiving a 60 kHz reference radio wave is about 7 Hz. Therefore, if f _A is set to 7 Hz and TG _A1 , TG _A2 , TG _B1, and TG _B2 are all turned on, the center frequency ω ₀ is set to 1946 Hz. . That is, when a 40 kHz reference radio wave is received, TG _A1 , TG _A2 , TG _B1 and TG _B2 are all turned on, and an intermediate frequency of 1946.83871 Hz is filtered near the center frequency ω ₀ (1946 Hz) of the BPF circuit 110. When a 60 kHz reference radio wave is received, only TG _A1 and TG _A2 are turned OFF, and filtering of an intermediate frequency of 1953.16129 Hz is performed near the center frequency ω ₀ (1946 + 7 = 1955 Hz) of the BPF circuit 10. be able to.

Further, the difference between the intermediate frequency when the 77.5 kHz reference radio wave is received in the first embodiment and the intermediate frequency when the 77.5 kHz reference radio wave is received in the second embodiment is about 375 Hz. Therefore, when f _B is set to 375 Hz and all of TG _A1 , TG _A2 , TG _B1 and TG _B2 are turned ON, if the center frequency ω ₀ is set to 1951 Hz, good operation can be performed. That is, when a reference radio wave other than 77.5 kHz is received, filtering of each intermediate frequency is performed in the state of the first embodiment, and when a reference radio wave of 77.5 kHz is received in the first embodiment, in the second embodiment. The data Dr and Dm are set in the state, and only TG _B1 and TG _B2 are turned OFF, and filtering of the intermediate frequency of 2326.35294 Hz can be performed near the center frequency ω ₀ (1951 + 375 = 2326 Hz) of the BPF circuit 110. . This is because Fr (1927.529 Hz) in the case of receiving the 77.5 kHz reference radio wave in Example 2 is different from Fr (910.2222 Hz) in the case of receiving the 77.5 kHz reference radio wave in Example 1. This is because the operation of the phase comparison circuit 4c is more stable because of the high frequency.

  As described above, in the PBF 110 shown in FIG. 5, the center frequency adjustment unit 112 can finely adjust and / or adjust the center frequency. As a result, it has become possible to increase the degree of freedom in designing the electronic timepiece with radio wave reception function according to the present invention.

It is a block diagram which shows schematic structure of the electronic timepiece with a radio wave reception function according to the present invention. It is a figure which shows an example of the frequency characteristic of a BPF circuit. It is a figure for demonstrating the utilization range of the center frequency of the BPF circuit used for the electronic timepiece with a radio wave reception function concerning the present invention. It is the figure which showed the specific numerical value in Examples 1-3 and Comparative Examples 1-3. It is a figure which shows the other BPF circuit which can be utilized for the electronic timepiece with a radio wave reception function according to the present invention. FIG. 6 is a diagram illustrating an operation example of the BPF circuit illustrated in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 Tuning part 3 Oscillation circuit 4 Local oscillation circuit 4a Main counter 4b Reference counter 4c Phase comparison circuit 4d Oscillation part 5 Tuning part 6 Control part 7 Clock part 8 Display part 9 MIX circuit 10, 110 BPF circuit 11 Detection circuit 12 Operation Part

Claims (6)

In electronic watches,
An antenna for receiving multiple standard radio waves,
A designation unit for designating one of the plurality of standard radio waves, a reference signal oscillation unit for generating a reference signal,
A clock unit that performs a clock operation based on the reference signal;
A reference counter that divides the reference signal to generate a reference frequency according to a specified standard radio wave;
A local frequency oscillator that outputs a local frequency according to a standard radio wave designated based on the reference frequency;
A main counter that divides the local oscillation frequency to generate a main frequency;
A phase comparator that controls the local frequency oscillator by comparing the reference frequency with the main frequency;
A MIX unit for generating an intermediate frequency corresponding to the designated standard radio wave by mixing the designated standard radio wave and the local oscillation frequency;
An integrated circuit, having a predetermined bandwidth and center frequency, and having a BPF unit for filtering the intermediate frequency;
The intermediate frequency is set so that all of the plurality of standard radio waves are within the range of the bandwidth, the center frequency is 1.0 kHz or more and 10.0 kHz or less, and the reference frequency is 500 Hz or more. An electronic watch characterized by   2. The electronic timepiece according to claim 1, wherein the plurality of standard radio waves include at least two of 40 kHz, 60 kHz, 68.5 kHz, and 77.5 kHz.   The electronic timepiece according to claim 1 or 2, wherein the frequency of the reference signal is 32768 Hz.   4. The apparatus according to claim 1, further comprising a control unit that acquires time information by detecting an intermediate frequency that has passed through the BPF unit, and corrects a clock operation of the clock unit based on the time information. Electronic watch as described in.   The electronic timepiece according to any one of claims 1 to 4, further comprising a center frequency adjustment unit for performing fine adjustment or adjustment of the center frequency.   The electronic timepiece according to claim 1, wherein the center frequency is 1950 Hz, 2134 Hz, or 2325 Hz.

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