Time signal repeater and time correction system using the same

A time signal repeater, capable of selectively relaying standard time radio signals having different modulation frequencies and correcting the time based on the plurality of standard time radio signals without changing a radio correction clock side, including an antenna portion capable of receiving a standard time radio signal by a set resonance frequency, an oscillating circuit outputting a signal having a frequency of the received standard time radio signal in synchronization with the standard time radio signal received by the antenna portion, at least one frequency conversion circuit converting the frequency of the output signal of the oscillating circuit, a receiving circuit receiving as input the standard time radio signal received by the antenna portion and correcting a time of an internal clock according to a time code included in the received radio signal, a transmission circuit generating a time radio signal including a time code based on the internal clock based on the output signal of the oscillating circuit or the signal converted in frequency by the frequency conversion circuit at the time of transmission, and a selecting circuit receiving as input the output signal of the oscillating circuit or the signal converted in frequency by the frequency conversion circuit to the transmission system circuit, and a time correction system using the same.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a time signal repeater which relays a
 radio signal including a time code for a radio correction clock receiving
 a radio signal to correct its time and to a time correction system using
 the same.
 2. Description of the Related Art
 A radio correction clock receives, for example, a standard time radio
 signal of a long wave (for example, 40 kHz in Japan) transmitting a
 standard time and corrects the time based on the received radio signal to
 display the precise time.
 This type of radio correction clock has built into it a receiving circuit
 receiving a standard time radio signal and a control circuit for driving a
 hand driving system based on the received signal to correct the time. In
 the radio correction clock, the positions of the hands are corrected to
 positions according to the time code of the received radio signal.
 A radio correction clock exclusively receives the standard time radio
 signal. There are many cases where it is placed in a location which the
 radio signal can hardly reach, for example, is in an apartment building or
 basement, and cannot receive the signal.
 In order to eliminate this restriction on the location where the radio
 correction clock is placed, it has been proposed to provide a time signal
 repeater for receiving the standard time radio signal and modulating the
 received time signal by a predetermined carrier and transmitting the
 modulated signal, and to have the radio correction clock receive the
 signal transmitted from the repeater to correct the time (see for example
 Japanese Unexamined Patent Publication (Kokai) No. 5-333170).
 Summarizing the problem to be solved by the invention, the modulation
 frequency of the standard time radio signal differs by country.
 For example, the modulation frequency is 40 kHz in Japan, 60 kHz in the
 U.S., and 77.5 kHz in Germany.
 As opposed to this, in the time signal repeaters currently proposed, the
 resonance frequency of the receiving antenna portion is fixed, so it is
 possible to use the repeaters in only one country.
 Further, it may be considered to change the reception frequency of the
 radio correction clock to the frequency of the time signal repeater. This
 change, however, would be complicated and would involve both hardware and
 software, therefore this is not practical in terms of cost etc.
 SUMMARY OF THE INVENTION
 An object of the present invention is to provide a time signal repeater
 capable of selectively relaying standard time radio signals having
 different modulation frequencies and thereby enabling correction of time
 based on a plurality of standard time radio signals without changes at the
 radio correction clock side and a time correction system using the same.
 According to a first aspect of the present invention, there is provided a
 time signal repeater which relays a radio signal including a time code for
 a radio correction clock receiving a standard time radio signal to correct
 the time, comprising an antenna portion capable of setting a plurality of
 resonance frequencies and receiving the standard time radio signal by a
 set resonance frequency, an oscillating circuit for outputting a signal
 having a frequency of the received standard time radio signal and
 synchronized with the standard time radio signal received by the antenna
 portion, at least one frequency conversion circuit for converting the
 frequency of the output signal of the oscillating circuit, a receiving
 circuit for receiving as input the standard time radio signal received by
 the antenna portion and correcting the time of an internal clock according
 to the time code included in the received radio signal, a transmission
 circuit for generating a time radio signal including a time code based on
 the internal clock based on the output signal of the oscillating circuit
 or the signal converted in frequency by the frequency conversion circuit
 at the time of transmission, and a selecting circuit for receiving as
 input the output signal of the oscillating circuit or the signal converted
 in frequency by the frequency conversion circuit to the transmission
 circuit.
 According to a second aspect of the present invention, there is provided a
 time correction system comprising a radio correction clock fixed in
 reception frequency, receiving a standard time radio signal or radio
 signal obtained by relaying the standard time signal, and correcting the
 time to a time according to a time code included in the received signal,
 and a time signal repeater which has an antenna portion capable of setting
 a plurality of resonance frequencies and receiving the standard time radio
 signal with a set resonance frequency, an oscillating circuit for
 outputting a signal having a frequency of the received standard time radio
 signal and synchronized with the standard time radio signal received by
 the antenna portion, at least one frequency conversion circuit for
 converting the frequency of the output signal of the oscillating circuit,
 a receiving circuit for receiving as input the standard time radio signal
 received by the antenna portion and correcting the time of an internal
 clock according to the time code included in the received radio signal, a
 transmission circuit for generating a time radio signal including a time
 code based on the internal clock based on the output signal of the
 oscillating circuit or the signal converted in frequency by the frequency
 conversion circuit at the time of transmission, and a selecting circuit
 for receiving as input the output signal of the oscillating circuit or the
 signal converted in frequency by the frequency conversion circuit to the
 transmission circuit.
 Further, in the present invention, the transmission circuit modulates an
 input signal with a different modulation system from an amplitude
 modulation system of the standard time radio signal.
 Summing up, according to the present invention, in the time signal
 repeater, the resonance frequency is set to a frequency corresponding to
 the modulation frequency of the standard radio signal transmitted from a
 radio transmission base station.
 When a standard time radio signal having a predetermined format is
 transmitted from the radio transmission base station in this state, it is
 received by the receiving antenna portion of the time signal repeater and
 input to the oscillating circuit and the receiving circuit.
 In the oscillating circuit, a signal having the frequency of the received
 standard time radio signal in synchronization with the standard time radio
 signal received at the antenna portion is output.
 Further, in the receiving circuit, the internal clock is corrected the time
 according to the time code included in the standard time radio signal
 received by the antenna portion.
 Then, at the time of transmission, when the frequency of the output signal
 of the oscillating signal is the same as the reception frequency of the
 radio correction clock, the output signal of the oscillating circuit is
 selected by the selecting circuit and input to the transmission circuit.
 When the frequency of the output signal of the oscillating signal is
 different from the reception frequency of the radio correction clock, the
 output signal of the frequency conversion circuit, which converts the
 frequency of the output signal of the oscillating circuit to a frequency
 the same as the reception frequency of the radio correction clock, is
 selected by the selecting circuit and input to the transmission circuit.
 In the transmission circuit, at the time of the transmission, a time radio
 signal including a time code based on the internal clock is generated
 based on the output signal of the oscillating circuit or the signal
 converted in frequency by the frequency conversion circuit and the
 generated signal is transmitted to the radio correction clock.
 In the radio correction clock, the time correction is performed according
 to the time code included in the standard time radio signal or the radio
 signal transmitted from the time signal repeater.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 Below, preferred embodiments will be described with reference to the
 accompanying drawings.
 FIG. 1 is a block diagram of an embodiment of a time correction system
 using a time signal repeater according to the present invention.
 As shown in FIG. 1, the present time correction system is comprised of a
 radio transmission base station (hereinafter referred to as a "key
 station") 1 which transmits a standard time radio signal (JG2AS) with a
 long wave (40 kHz), a time signal repeater 2, and a radio correction clock
 3.
 The key station 1 performs amplitude modulation with respect to and
 transmits the long wave (40 kHz) standard time radio signal S1 of the
 format, for example, as shown in FIG. 2A.
 The format of the long wave (40 kHz) standard time radio signal S1 sent by
 the key station 1 and transmitting the standard time at a high precision
 is specifically, in the case of a "1" signal, a signal of 40 kHz
 transmitted for a period of 500 ms (0.5 second) in one second, in the case
 of a "0" signal, a signal of 40 kHz transmitted for a period of 800 ms
 (0.8 second) in one second, and in the case of a "P" signal (synchronizing
 signal), a signal of 40 kHz transmitted for a period of 200 ms (0.2
 second) in one second.
 FIG. 2A shows an example of a waveform in the case where the data is
 (1,0,1).
 FIG. 3 shows an example of the time code of a standard time radio signal
 (JG2AS).
 The example shows that it is the 114th day from January 1, 17:25. In this
 standard time radio signal, the code "0" continues nine consecutive times
 from the 50th second for synchronization use.
 The time signal repeater 2 receives the standard time radio signal S1
 including the time code and having a predetermined frequency (for example,
 40 kHz or 60 kHz) amplitude modulated and transmitted from the key station
 1, corrects the internal clock to the time according to the time code
 included in the received standard time radio signal, generates a time
 radio signal S2 having a frequency of 40 kHz included in the same
 frequency band of the standard radio signal, having the same format as a
 JG2AS baseband signal, and including a time code based on the corrected
 internal clock, and transmits the same to the radio correction clock 3
 placed, for example, indoors in a predetermined transmission time band
 Specifically, as shown in FIG. 1, the time signal repeater 2 is configured
 by a receiving antenna portion 201, a reception use RF amplifier 202, a
 detection circuit 203, a rectifier circuit 204, an integrating circuit
 205, a microcomputer 206, a phase locked loop (PLL) circuit 207 serving as
 an oscillating circuit, a frequency conversion circuit 208, a selecting
 circuit 209, an analog switch 210, a transmission use RF amplifier 211,
 and a transmission antenna 212.
 The reception circuit is configured by the receiving antenna portion 201,
 the reception use RF amplifier 202, the detection circuit 203, the
 rectifier circuit 204, the integrating circuit 205, and the microcomputer
 206, while the transmission circuit is configured by the microcomputer
 206, the PLL circuit 207, the frequency conversion circuit 208, the
 selecting circuit 209, the analog switch 210, the transmission use RF
 amplifier 211, and the transmission antenna 212.
 The receiving antenna portion 201 is capable of being set to a plurality of
 resonance frequencies, for example, 40 kHz and 60 kHz, so as to enable it
 to handle the frequencies of different standard time radio signals.
 Specifically, the receiving antenna portion 201 is configured by a
 resonance coil L201, capacitors C201 and C202, and switch SW201.
 One end of the resonance coil L201 is connected to a first electrode of the
 capacitor C201 and a first contact a of the switch SW201, while another
 end is connected to second electrodes of the capacitors C201 and C202 and
 a ground line.
 Further, a second contact b of the switch SW201 is connected to a first
 electrode of the capacitor C202.
 Note that the resonance frequency is given by {1/(2.pi.(LC).sup.1/2}.
 Further, an inductance L of the resonance coil 201 is set to 1.583 mH, a
 capacity Ca of the capacitor C201 is set to 4.44 nF, and a capacity Cb of
 the capacitor C202 is set to 5.56 nF (Ca+Cb=10 nF).
 The switch SW201 is set to ON and OFF by a control signal CTL.
 In the case of the present configuration, when setting the resonance
 frequency to 40 kHz, the control signal CTL is set to a high level, then
 the switch SW201 is controlled to the ON state.
 On the other hand, when setting the resonance frequency to 60 kHz, the
 control signal CTL is set to a low level, then the switch SW201 is
 controlled to the OFF state.
 Note that, the level of the control signal CTL is set, for example, by the
 operation of a not illustrated change-over switch.
 In the time signal repeater 2, the standard time radio signal S1 received
 by the receiving antenna portion 201 is converted to the baseband signal
 of the standard time radio signal S1 shown in FIG. 2B via the reception
 use RF amplifier 202, the detection circuit 203, the rectifier circuit
 204, and the integrating circuit 205 and input to the microcomputer 206
 and the PLL circuit 207.
 As shown in the flow chart of FIG. 4, the microcomputer 206 receives the
 baseband signal from the integrating circuit 205, decodes the time code of
 JG2AS, obtains the time data, for example, the hour:minute:00 second, and
 corrects the internal clock (ST1) accordingly.
 Next, the microcomputer 206 generates the time data to be transmitted based
 on the time which the internal clock is counting in a predetermined
 transmission time band, for example, at 2:38 a.m. (ST2).
 Then, the microcomputer 206 outputs the time data of the same format as the
 baseband signal of JG2AS to a control terminal of the analog switch 210 as
 a gate pulse S206 (ST3), makes the analog switch 210 generate a time radio
 signal S2, and makes the transmission use RF amplifier 211 transmit the
 same.
 The PLL circuit 207 is configured by a phase comparator 2071, a low-pass
 filter (LPF) 2072, and a voltage-controlled oscillator (VCO) 2073.
 The phase comparator 2071 is configured by for example a multiplier. The
 phase comparator 2071 compares a phase of the standard time signal S202
 output from the RF amplifier 202 with a phase of an oscillating signal
 S207 output from the VCO 2073, and outputs a phase difference thereof to
 the LPF 2072 as a signal S2071.
 Then, the PLL circuit 207 outputs an oscillating signal S207 synchronized
 in phase with the received standard time radio signal S1 and the same in
 frequency as the frequency of the standard time radio signal S1.
 The frequency conversion circuit 208 is configured by for example a 2/3
 frequency divider. The frequency conversion circuit 208 divides to 2/3 the
 60 kHz frequency of the oscillating signal S207 from the PLL circuit 207
 input via the selecting circuit 209 to convert the 60 kHz frequency to a
 40 kHz frequency and outputs the same to the analog switch 210 via the
 selecting circuit 209.
 The selecting circuit 209 inputs the oscillating signal S207 of the PLL
 circuit 207 directly or via the frequency conversion circuit 208 to the
 analog switch 210 according to the set level of a selection signal SLC.
 The selecting circuit 209 is configured by a switch circuit SW2091 and a
 switch circuit SW2092.
 A fixed contact a of the switch circuit SW2091 is connected to an output
 line of the oscillating signal S207 of the PLL circuit 207, a change-over
 contact b is connected to a contact a of the analog switch 210, and a
 change-over contact c is connected to an input line of the frequency
 conversion circuit 208.
 A fixed contact a of the switch circuit SW2092 is connected to an output
 line of the frequency conversion circuit 208, a change-over contact b is
 held in an open state, and a change-over contact c is connected to a
 contact a of the analog switch 210.
 When the frequency of the received standard time radio signal is 40 kHz,
 the selection signal SLC is for example set to a high level and the fixed
 contacts a of the switch circuits SW2091 and SW2092 are connected to the
 change-over contacts b thereof.
 When the frequency of the received standard time radio signal is 60 kHz,
 the selection signal SLC is for example set to a low level and the fixed
 contacts a of the switch circuits SW2091 and SW 2092 are connected to the
 change-over contacts c thereof.
 Note that the level of the selection signal SLC is set, for example,
 according to the operation of a not illustrated change-over switch.
 The analog switch 210 turns on and off the oscillating signal S207 output
 from the PLL circuit 207 or the output signal S208 of the frequency
 conversion circuit 208 by the gate pulse S206 from the microcomputer 206
 to obtain an amplitude modulated RF signal.
 The amplitude modulated RF signal is amplified by the transmission use RF
 amplifier 211 and transmitted from the transmission antenna 212 as the
 radio signal S2 having the same format as JG2AS shown in FIG. 2A.
 Note that, in the time signal repeater 2, a radio signal of 40 kHz from the
 transmission antenna 212 circulates to the receiving antenna portion 201,
 so the PLL circuit 207 is liable to find it hard to lock the phase
 synchronization loop, but it is possible to solve the problem explained
 below.
 The 40 kHz standard time radio signal to be transmitted from June 1999 is a
 100% to 10% amplitude modulated wave as shown in FIG. 5A.
 As opposed to this, as shown in FIG. 5B and FIG. 2A, the time radio signal
 S2 transmitted by the present time signal repeater 2 is transmitted as a
 100% to 10% amplitude modulated wave, so the phase synchronization loop is
 locked at the PLL circuit 207 at a 0% transmission radio signal even if
 both the transmission frequency and reception frequency are 40 kHz.
 Note that it is possible to configure the time signal repeater 2 so as to
 constantly transmit the radio signal S2, however, in the present
 embodiment, the time signal repeater 2 is configured so as to transmit the
 radio signal S2 one time a day only at a very special time, for example,
 at 2:38 a.m.
 In principal, the radio correction clock 3 receives the predetermined
 frequency (40 kHz) standard time radio signal S1 including the time code
 amplitude modulated and transmitted from the key station 1 or the 40 kHz
 frequency time radio signal S2 transmitted from the time signal repeater
 2, corrects the positions of the hands to the time indicated by the time
 code when the reception state of the standard time radio signal S1 or the
 time radio signal S2 is good, and informs the user of the poor reception
 of the radio signal when the reception state of the same is not good.
 FIG. 6 is a block diagram of the configuration of an embodiment of the
 signal processing circuit of the radio correction clock according to the
 present invention, FIG. 7 is a sectional view of an embodiment of a hand
 position detecting apparatus of the radio correction clock according to
 the present invention, and FIG. 8 is a principal plane view of the hand
 position detecting apparatus of the radio correction clock according to
 the present invention.
 In the figures, 30 denotes a signal processing circuit, 31 denotes a time
 radio signal receiving system, 32 denotes a reset switch, 33 denotes an
 oscillating circuit, 34 denotes a control circuit, 35 denotes a drive
 circuit, 36 denotes a light emitting element functioning as a warning
 means, 37 denotes a buffer circuit, 38 denotes a drive circuit, Vcc
 denotes a power source voltage, C.sub.1 to C.sub.3 denote capacitors,
 R.sub.1 to R.sub.8 denote resistance elements, 100 denotes a clock body,
 200 denotes a second hand driving system, 300 denotes a first reflection
 type optical sensor, 400 denotes a minute hand driving system, 500 denotes
 an hour hand wheel, 600 denotes a minute (changing) wheel functioning as
 an intermediate wheel, 700 denotes a manual correction shaft, 800 denotes
 a rotary detection plate, and 900 denotes a second reflection type optical
 sensor.
 The time radio signal receiving system 31 is configured by a receiving
 antenna 31a and a long wave receiving circuit 31b which receives a long
 wave (for example 40 kHz) including a time code signal transmitted, for
 example, by the key station 1, performs predetermined signal processing,
 and outputs the same as a pulse signal S31 to the control circuit 34. Note
 that, though not illustrated here, the long wave receiving circuit 31b is
 constituted by an RF amplifier, a detection circuit, a rectifier circuit,
 and an integrating circuit in the same way as the receiving system of the
 time signal repeater.
 The reset switch 32 is turned on when the different states of the control
 circuit are returned to the initial state.
 When the reset switch 32 is turned on or a not illustrated battery is set,
 the radio correction clock 3 enters an initial correction mode.
 The oscillating circuit 33 is constituted by a crystal oscillator CRY and
 capacitors C.sub.2 and C.sub.3 and supplies a basic clock having a
 predetermined frequency to the control circuit 34.
 The control circuit 34 has a not illustrated minute hand counter, second
 hand counter, standard minute and second counter, and the like. At the
 initial correction mode, the control circuit 34 receives the pulse signal
 S31 from the time radio signal receiving system 31 and for example
 compares a reception state of the received standard time radio signal with
 a predetermined reference range. When the reception state is within the
 reference range, the control circuit 34 outputs control signals CTL.sub.1
 and CTL.sub.2 to a second hand use stepping motor 210 and an hour hand and
 minute hand use stepping motor 410 via the buffer 37 to initially set the
 positions of the hands, namely to reset them. When the reception state is
 outside the reference range, the control circuit 34 outputs a driving
 signal DR.sub.1 to the drive circuit 35, without outputting the control
 signals CTL.sub.1 and CTL.sub.2, to cause the light emitting element 36
 serving as the warning means to emit light and inform the user that
 reception of the radio signal is almost impossible.
 Further, after the reset operation when the reception state is within the
 reference range, the control circuit 34 decodes the received radio signal.
 When the result of the decoding is that it is possible to convert the same
 to time date, in other words, to reproduce the time data, it controls the
 count operations of the different counters based on the basic clock from
 the oscillating circuit 33 and outputs the control signals CTL.sub.1 and
 CTL.sub.2 to the second hand use stepping motor 210 and the hour hand and
 minute hand use stepping motor 410 via the buffer 37 according to the
 input levels of the detecting signals DT.sub.1 and DT.sub.2 from the first
 and second reflection type optical sensors 300 and 900 in order to control
 the rotation and thereby controls the correction of the time.
 On the other hand, when the result of the decoding is that it is impossible
 to convert the same to time data, the control circuit 34 outputs the
 driving signal DR.sub.1 to the drive circuit 35, without outputting the
 control signals CTL.sub.1 and CTL.sub.2, to cause the light emitting
 element 36 to emit light and inform the user of poor reception of the
 radio signal.
 By this, the control circuit 34 completes the operation of the initial
 correction mode.
 Further, the control circuit 34 controls the operation of the normal
 correction mode after completing the operation of the initial correction
 mode.
 In the normal correction mode, the control circuit 34 makes a not
 illustrated power source supply driving power to the time radio signal
 receiving system 31 one minute before and after every hour, including the
 exact hour, so as to enable the reception of the hourly standard time
 radio signal S1 from the key station 1. Also, the control circuit 34 makes
 the not illustrated power source supply driving power to the time radio
 signal receiving system 31 one minute before and after 2:38 a.m.,
 including 2:38 a.m., so as to enable reception of the radio signal S2 from
 the time signal repeater 2.
 In this way, the control circuit 34 controls a receivable time band of the
 standard time radio signal S1 from the key station 1 and a receivable time
 band of the radio signal S2 from the time signal repeater 2 to different
 times so as that for example the radio signal S2 from the time signal
 repeater 2 does not become radio interference when the standard time radio
 signal S1 is received.
 At the normal correction mode, in principal, the control circuit 34
 receives the standard time radio signal S1 from the key station 1 and
 decodes the received radio signal. When the result of the decoding is that
 it is possible to convert the same to time data, it controls the count
 operations of the different counters based on the basic clock from the
 oscillating circuit 33 and outputs the control signals CTL.sub.1 and
 CTL.sub.2 to the second hand use stepping motor 210 and the hour hand and
 minute hand use stepping motor 410 via the buffer 37 according to the
 input levels of the detecting signals DT.sub.1 and DT.sub.2 from the first
 and record reflection type optical sensors 300 and 900 in order to control
 the rotation and thereby controls the correction of the time. It also sets
 a standard radio signal normal reception flag showing that the standard
 time radio signal has been normally received.
 When setting the standard radio signal normal reception flag, the control
 circuit 34 does not receive the radio signal S2 from the time signal
 repeater 2, namely does not make the not illustrated power source supply
 the driving power to the standard radio signal receiving system 31 one
 minute before and after 2:38 a.m., including 2:38 a.m., while resets the
 standard radio signal normal reception flag, receives the hourly standard
 time radio signal S1 from the key station 1, and corrects the time.
 On the other hand, when the result of the decoding is that it is impossible
 to convert the same to time data, the control circuit 34 outputs, for
 example, the driving signal DR.sub.1 to the drive circuit 35, without
 outputting the control signals CTL.sub.1 and CTL.sub.2, to cause the light
 emitting element 36 serving as the warning means to emit light and inform
 the user of poor reception of the radio signal.
 In this case, the control circuit 34 receives the radio signal S2 from the
 time signal repeater 2. When the reception is normal, it corrects the time
 according to the time code of the radio signal S2 obtained by the
 decoding.
 When the reception is not normal, the control circuit 34 considers the
 place where the time signal repeater 2 placed to be unsuitable and outputs
 for example the driving signal DR.sub.1 to the drive circuit 35, without
 outputting the control signals CTL.sub.1 and CTL.sub.2, to cause the light
 emitting element 36 serving as the warning means emit light to inform the
 user.
 After the completion of the time correction or when the reception of the
 radio signal S2 from the time signal repeater 2 is not normal and the
 control circuit 34 makes the light emitting element 36 emit light to
 inform the user etc., the control circuit 34 resets the standard radio
 signal normal reception flag, receives the hourly standard time radio
 signal S1 from the key station 1, and returns to the time correction mode.
 The drive circuit 35 is constituted by an npn type transistor Q1 and
 resistance elements R.sub.1 and R.sub.2.
 The collector of the transistor Q1 is connected to a cathode of a light
 emitting element constituted by a light emitting diode, the emitter is
 grounded, and the base is connected to an output line of the driving
 signal DR.sub.1 of the control circuit 34 via the resistance element
 R.sub.2.
 The resistance element R.sub.1 is connected to a supply line of the power
 source voltage Vcc and an anode of the light emitting element 36.
 Namely, the light emitting element 36 is connected to the drive circuit 35
 so as to emit light when a high level driving signal DR.sub.1 is output
 from the control circuit 34.
 The drive circuit 38 is constituted by npn type transistors Q2 and Q3 and
 resistance elements R.sub.5 to R.sub.8.
 As shown in FIG. 7, the clock body 100 has a center plate 120 arranged at
 the substantially center portion of the space formed by a lower plate 110
 and an upper plate 130 in a state connected to the lower plate 110. The
 second hand driving system 200, the first reflection type optical sensor
 300, the second driving system 400, the hour hand wheel 500, the minute
 (changing) wheel 600, the manual correction shaft 700, and the second
 reflection type optical sensor 900 are fixed or axially supported with
 respect to predetermined positions of the lower plate 110, the center
 plate 120, and the upper plate 130 inside of the space.
 The second hand driving system 200 is configured by a first stepping motor
 210, a first fifth-wheel 220, and a second hand wheel 230.
 The first stepping motor 210 has a stator 210a placed on the lower plate
 110 and has a rotor 210b axially supported with respect to the lower plate
 110 and the upper plate 130. It is controlled in direction of rotation,
 angle of rotation, and speed of rotation based on the control signal
 CTL.sub.1 output from the control circuit 34 input via the buffer 37.
 The first fifth-wheel 220 is axially supported with respect to the lower
 plate 110 and the upper plate 130, has gear teeth meshed with the rotor
 210b of the first stepping motor 210, and reduces the speed of the rotor
 210 to a predetermined speed.
 The first fifth-wheel 220 is configured so as to rotate once every for
 example 15 seconds and is formed with a slit 220a in part of the area
 overlapping the second hand wheel 230.
 The second hand wheel 230 has one end of the shaft supported with respect
 to the upper plate 130 and has the other side passed through the center
 plate 120 toward the lower plate 110 and press-fit with a second hand
 shaft 230a.
 The second hand shaft 230a is passed through an opening 440b of a minute
 hand pipe 440a passing through the lower plate 110 and projecting out to a
 surface side where the face of the clock is formed. A not illustrated
 second hand is attached to the tip of the pipe.
 The second hand wheel 230 has a second hand pinion meshed with a pinion of
 the first fifth-wheel 220 so as to rotate once every 60 seconds.
 Further, a light reflecting plane 230b is formed at part of an area of
 overlap of the first fifth-wheel 220 with the second hand wheel 230 so as
 to face the slit 220a formed on the first fifth-wheel 220.
 The second hand driving system 220 is configured so that the second hand
 points to 12 when the light reflecting plane 230b faces the slit 220a,
 namely the two exactly match each other.
 The first reflection type optical sensor 300 is provided with a light
 emitting element 310 constituted by a light emitting diode and a light
 receiving element 320 constituted by an npn type transistor in parallel
 and is arranged on the upper plate 130 so that a light emitting portion of
 the light emitting element 310 and a light receiving surface of the light
 receiving element 320 are near the plane formed by the light reflecting
 plane 230b of the second hand wheel 230 via the slit 130a formed in the
 upper plate 130 and further the slit 220a of the first fifth-wheel 220.
 An anode of light emitting element 310 of the first reflection type optical
 sensor 300 is connected to one end of the resistance element R.sub.5 of
 the drive circuit 38 having another end connected to a supply line of the
 power source voltage Vcc, while a cathode is connected to a collector of
 the driving transistor Q2 provided in the drive circuit 38.
 The emitter of the driving transistor Q2 is grounded, and the base is
 connected to an output line of the driving signal DR.sub.2 of the control
 circuit 34 via the resistance element R.sub.6.
 Namely, the light emitting element 310 is connected to the drive circuit 38
 so as to emit light when a high level driving signal DR.sub.2 is output
 from the control circuit 34.
 The collector of the light receiving element 320 of the first reflection
 type optical sensor 300 is connected to the supply line of the power
 source voltage Vcc and the control circuit 34, while the emitter is
 grounded.
 Namely, the light receiving element 320 inputs a low level detecting signal
 DT.sub.2 to the control circuit 34 only when the light emitted from the
 light emitting element 310 reaches the second hand wheel 320 via the slits
 130a and 220a and the light reflected by the light reflecting plane 230b
 is received via the slits 130a and 220a.
 The minute hand driving system 400 is configured by a second stepping motor
 410, a second fifth-wheel 420, a third wheel 430, and a minute hand wheel
 440.
 The second hand stepping motor 410 has a stator 410a placed on the lower
 plate 110, has a rotor 410b axially supported with respect to the lower
 plate 110 and the upper plate 130, and is controlled in direction of
 rotation, angle of rotation, and speed of rotation based on the control
 signal CTL.sub.2 output from the control circuit 34 via the buffer 37.
 The second fifth-wheel 420 is axially supported with respect to the lower
 plate 110 and the upper plate 130, has gear teeth meshed with the rotor
 410b of the second stepping motor 410, and reduces the speed of the rotor
 410b to a predetermined speed.
 The third wheel 430 has one end of a shaft portion axially supported with
 respect to the upper plate 130, has the other end passed through the
 center plate 120, and has gear teeth meshed with a pinion of the second
 fifth-wheel 420.
 The minute hand wheel 440 forms an approximate T-shape in cross-section
 with an opening 440b at its center, has one end of the minute hand pipe
 440A axially supported at the center plate 120, and has the shaft portion
 of the other end passed through an opening 500b of an hour hand pipe 500a
 of the hour hand wheel 500 passing through the lower plate 110 and
 projecting to the surface where the face of the clock is formed. A not
 illustrated minute hand is attached to the tip of the pipe.
 The minute hand wheel 440 is configured to rotate once every 60 minutes.
 Further, the second hand shaft 230a is inserted through the opening 440b as
 mentioned above. The gear teeth mesh with a pinion of the third wheel 430.
 The minute hand wheel 440 is provided with a so-called slip mechanism.
 The hour hand wheel 500 forms an approximate T-shape in cross-section with
 an opening 500b at its center, has gear teeth provided in the clock body
 100 and has an hour hand pipe 500a passed though the lower plate 110 and
 projecting to the face side of the clock. A not illustrated hour hand is
 attached to the tip of the pipe.
 The hour hand wheel 500 is configured so as to rotate 30.degree. every hour
 and once every 12 hours.
 Further, the minute hand pipe 400a is inserted through the opening 500b as
 mentioned above.
 The slits 500d serving as the first light transmitting portions are formed
 in the surface 500c of the hour hand wheel 500 facing the minute hand
 wheel 440.
 As shown in FIG. 9, the slits 500d of the hour hand wheel 500 are formed in
 11 locations, that is all but one location, in the 12 equally spaced
 locations 30.degree. each apart in the circumferential direction of the
 hour hand wheel 500. Namely, the slits are formed so as not to detect a
 position of one hour among the 12 hours.
 The minute (changing) wheel 600 is axially supported with respect to a
 projection portion 110a formed on the lower plate 110, has gear teeth
 meshed with the minute hand pipe 440a of the minute hand wheel 440, has a
 pinion meshed with the gear teeth of the hour hand wheel 500, reduces the
 speed of the minute hand wheel 440 to a predetermined speed, and transfers
 the rotation to the hour hand wheel 500.
 Further, the date wheel 600 is configured so as to rotate once every N (N
 is a positive integer) number of hours, has gear teeth meshed with a
 correction pinion 700a of the manual correction shaft 700, and is arranged
 so that part faces part of the rotary detection plate 800.
 The manual correction shaft 700 forms an approximate T-shape in
 cross-section, has a correction pinion 700a axially supported with respect
 to a projection formed on the lower plate 110 in the state passing through
 an opening 130b formed in the upper plate 130, and has a head portion 700b
 arranged in a state projecting out from the upper plate 130 to the outside
 of the clock body 100.
 The manual correction shaft 700 is configured to rotate once every 60
 minutes at the same phase as the minute hand wheel 440. As explained
 above, the correction pinion 700a meshes with the gear teeth of the date
 wheel 600. When the minute hand wheel 440 is driven by the minute hand
 driving system 400, the shaft rotates at the same phase as the minute hand
 wheel 440 via the minute wheel 600. When the minute hand driving system
 400 is not operating, the shaft enables manual correction of the positions
 of the hands by rotating the head portion 700b.
 The rotary detection plate 800 forms a disk shape and is fixed at its
 center substantially coaxially with the shaft portion of the minute hand
 wheel 440 between the minute hand wheel 440 and the hour hand wheel 500 so
 as to rotate according to the rotation of the minute hand wheel 440.
 As shown in FIG. 10, a light reflecting plane 800a serving as a second
 light transmitting portion is formed at the part of an area of the rotary
 detection plate 800 overlapping the surface 500c of the hour hand wheel
 500 so as to face the slit 500d.
 The second reflection type optical sensor 900 is provided with a light
 emitting element 910 constituted by a light emitting diode and a light
 receiving element 920 constituted by an npn type transistor in parallel
 and is arranged on the lower plate 110 so that a light emitting portion of
 the light emitting element 910 and a light receiving surface of the light
 receiving element 920 are near the plane 800b formed by the light
 reflecting plane 800a of the rotary detection plate 800 via the slit 110c
 formed in the lower plate 110 and the slit 500d formed in the hour hand
 wheel 500.
 An anode of the light emitting element 910 of the second reflection type
 optical sensor 900 is connected to one end of the resistance element
 R.sub.7 of the drive circuit 38 having the other end connected to the
 supply line of he power source voltage Vcc, while a cathode is connected
 to a collector of the driving transistor Q3 provided in the drive circuit
 38.
 The emitter of the driving transistor Q3 is grounded, and the base is
 connected to an output line of the driving signal DR.sub.3 of the control
 circuit 34 via the resistance element R.sub.6.
 Namely, the light emitting element 910 is connected to the drive circuit 38
 so as to emit light when a high level driving signal DR.sub.3 is output
 from the control circuit 34.
 The collector of the light receiving element 920 of the second refection
 type optical sensor 900 is connected to the supply line of the power
 source voltage Vcc and the control circuit 34, and the emitter is
 grounded.
 Namely, the light receiving element 920 inputs a low level detecting signal
 DT.sub.2 to the control circuit 34 only when the light emitted from the
 light emitting element 910 reaches the surface 800b of the rotary
 detection plate 800 via the slit 500d and the light reflected by the light
 reflecting plane 800a is received via the slit 500d.
 Note that the relationship between the light reflecting plane 800a of the
 rotary detection plate 800 and the slit 500d of the hour hand wheel 500 is
 set so as that the not illustrated minute hand and hour hand point to
 every hour when the light reflecting area 800a faces the slit 500d.
 Next, an explanation will be made of the operation for control of time
 correction of the above configuration.
 Note that, here, the explanation will be made taking as an example a normal
 mode operation of the minute hand system.
 For example, in Japan, the long wave (40 kHz) standard time radio signal S1
 of the format for example as shown in FIG. 5A is amplitude modulated and
 transmitted from the key station 1.
 In this case, in the time signal repeater 2, for example, the change-over
 switch is set to the resonance frequency of 40 kHz.
 Due to this, the control signal CTL is supplied to the switch SW201 of the
 receiving antenna portion 201 at the high level and the selection signal
 SLC is supplied to the selecting circuit 209 at the high level.
 In the receiving antenna portion 210, the switch SW210 is held in an ON
 state by reception of the high level control signal CTL. Two capacitors
 C201 and C202 are connected in parallel to the resonance coil L210.
 Due to this, the resonance frequency of the receiving antenna portion 201
 is set to 40 kHz.
 Further, in the selecting circuit 209, the fixed contacts a of the switch
 circuit SW2091 and SW2092 are connected to the change-over contacts b by
 receiving a high level selection signal, namely, the connection is changed
 so as to directly input the oscillating signal S207 of the PLL circuit 207
 to the analog switch 210.
 In this state, the 40 kHz frequency standard time radio signal S1
 transmitted from the key station 1 is received by the receiving antenna
 portion 201 of the time signal repeater 2 and the receiving antenna 31a of
 the radio correction clock 3.
 In the time signal repeater 2, the standard time radio signal S1 received
 by the receiving antenna portion 201 is converted to the baseband signal
 of the standard time radio signal S1 shown in FIG. 2B through the
 reception use RF amplifier 202, the detection circuit 203, the rectifier
 circuit 204, and the integrating circuit 205. The converted baseband
 signal is input to the microcomputer 206 and the PLL circuit 207.
 In the PLL circuit 207, the phases of the standard time signal and the
 output signal of the VCO 2073 are compared in the phase comparator 2071,
 the phase of the oscillating signal S207 of the VCO 2073 is controlled to
 lock with the phase of the standard time signal, and the oscillating
 signal S207 synchronized in phase with the phase of the received standard
 time radio signal S1 and of the frequency of the standard time radio
 signal S1 is output from the VCO 2073.
 The oscillating signal S207 is directly input to the analog switch 210 via
 the selecting circuit 209.
 In the microcomputer 206, the baseband signal from the integrating circuit
 205 is received, the time code of JG2AS is decoded to obtain time data
 such as the hour-minute-00 seconds, and the internal clock is corrected.
 Further, at the predetermined transmission time (for example, 2:38 a.m.)
 band, the time data to be transmitted is generated based on a time counted
 by the internal clock.
 Next, the time data is output to the control terminal of the analog switch
 210 by the same format as the baseband signal of JG2AS as the gate pulse
 S206.
 Due to this, the time radio signal S2 shown in FIG. 5B is generated and
 transmitted from the transmission antenna 212 to the radio correction
 clock 3.
 Further, when using a radio correction clock 3 of a receiving frequency set
 to 40 kHz in the U.S., where the frequency of the standard time radio
 signal is 60 kHz, the change-over switch in the time signal repeater 2 is
 set to a resonance frequency of 60 kHz.
 Due to this, the control signal CTL is supplied to the switch SW201 of the
 receiving antenna portion 201 at the low level and the selection signal
 SLC is supplied to the selecting circuit 209 at the low level.
 In the receiving antenna portion 201, the switch SW201 is held in an OFF
 state by reception of a low level control signal CTL. By this, one
 capacitor C201 is connected in parallel to the resonance coil L201.
 Due to this, the resonance frequency of the receiving antenna portion 201
 is set to 60 kHz.
 Further, in the selecting circuit 209, the fixed contacts a of the switch
 circuit SW2091 and SW2092 are connected to the change-over contacts c by
 reception of the low level selection signal, namely, the connection is
 changed so as to input the oscillating signal S207 of the PLL circuit 207
 to the analog switch 210 via the frequency conversion circuit 208.
 In this state, the 60 kHz frequency standard time radio signal S1
 transmitted from the key station 1 is received by the receiving antenna
 portion 201 of the time signal repeater 2.
 In the time signal repeater 2, the standard time radio signal S1 received
 by the receiving antenna portion 201 is converted to the baseband signal
 of the standard time radio signal S1 shown in FIG. 2B through the
 reception use RF amplifier 202, detection circuit 203, rectifier circuit
 204, and integrating circuit 205 and input to the microcomputer 206 and
 input to the PLL circuit 207.
 In the PLL circuit 207, the phases of the standard time signal and the
 output signal of the VCO 2073 are compared in the phase comparator 2071,
 the phase of the oscillating signal S207 of the VCO 2073 is controlled to
 lock with the phase of the standard time signal, and the oscillating
 signal S207 synchronized in phase with the received standard time radio
 signal S1 and of the same frequency as the standard time radio signal S1
 is output from the VCO 2073.
 The oscillating signal S207 is input to the frequency conversion circuit
 208 via the selecting circuit 209.
 In the frequency conversion circuit 208, the 60 kHz frequency oscillating
 signal 207 is divided to 2/3 to convert it to a frequency of 40 kHz and is
 output to the analog switch 218.
 In the microcomputer 206, a similar operation is performed as in the case
 of 40 kHz explained above.
 Namely, the baseband signal of the integrating circuit 205 is received, the
 time code of JG2AS is decoded to obtain time data such as the
 hour-minute-00 second, and the internal clock is corrected.
 Further, at the predetermined transmission time (for example, 2:38 a.m.)
 band, the time data to the transmitted is generated based on the time
 counted by the internal clock.
 Then, the time data is output to the control terminal of the analog switch
 210 by the same format as the baseband signal of JG2AS as the gate pulse
 S206.
 Due to this, the time radio signal S2 shown in FIG. 5B is generated and
 transmitted from the transmission antenna 212 to the radio correction
 clock 3.
 In the radio correction clock 3, the control circuit 34 makes a not
 illustrated power source supply driving power to the time radio signal
 receiving system 31 one minute before and after every hour, including the
 hour, to enable reception of the standard time radio signal S1 from the
 key station 1 at every hour.
 Due to this, the long wave (for example 40 kHz) received by the receiving
 antenna 31a of the time radio signal receiving system 31 and including the
 time code signal transmitted from the key station 1 is subjected to
 predetermined signal processing at the long wave receiving circuit 31b and
 output to the control circuit 34 as the pulse signal S31.
 In the control circuit 34, the received radio signal is decoded. When the
 result of the decoding is that reception is normal, control is performed
 to correct the time by controlling the counts of the different counters
 based on the basic clock from the oscillating circuit 33 and output of the
 control signals CTL.sub.1 and CTL.sub.2 to the second hand use stepping
 motor 210 and the hour and minute hand use stepping motor 410 via the
 buffer 37 according to the input levels of the detecting signals DT.sub.1
 and DT.sub.2 from the first and second reflection type optical sensors 300
 and 900 in order to control the rotation.
 Next, the standard radio signal normal reception flag showing that the
 standard time radio signal has been normally received is set.
 When the current time is not the receiving time of the standard time radio
 signal S1 or the reception is judged not normal or the standard radio
 signal normal reception flag has been set, it is judged if the current
 time is the receiving time of the time radio signal S2 from the time
 signal repeater 2 or not.
 Here, when it is judged that the time is the receiving time of the time
 radio signal S2 and the standard radio signal normal reception flag has
 been set, driving power is not supplied from the not illustrated power
 source to the standard radio signal receiving system 31 one minute before
 and after 2:38 a.m., including 2:38 a.m. When the standard radio signal
 normal reception flag has been reset, the processing shifts to normal
 processing.
 On the other hand, when the standard radio signal normal reception flag has
 not been set, the driving power is supplied from the not illustrated power
 source to the standard radio signal receiving system 31 one minute before
 and after 2:38 a.m., including 2:38 a.m., to enable reception of the time
 radio signal S2 from the time signal repeater 2.
 In this case, the time radio signal transmitted from the time signal
 repeater 2 is received.
 At this time, when the reception is normal, control is performed to correct
 the time by controlling the counts of the different counters based on the
 basic clock from the oscillating circuit 33 and output of the control
 signals CTL.sub.1 and CTL.sub.2 to the second hand use stepping motor 210
 and the hour and minute hand use stepping motor 410 via the buffer 37
 according to the input levels of the detecting signals DT.sub.1 and
 DT.sub.2 from the first and second reflection type optical sensors 300 and
 900 in order to control the rotation.
 On the other hand, when the reception is not normal, it is considered that
 place where the time signal repeater 2 is placed is unsuitable, the
 driving signal DR.sub.1 is output to the drive circuit 35, without
 outputting the control signals CTL.sub.1 and CTL.sub.2, and the light
 emitting element 36 emits light to inform the user.
 As explained above, according to the present embodiment, there is provided
 a time signal repeater 2 comprising an antenna portion 201 capable of
 being set to a plurality of resonance frequencies and receiving a standard
 time radio signal S1 with a set resonance frequency, a PLL circuit 207
 outputting a signal S207 having a frequency of the received standard time
 radio signal in synchronization with the standard time radio signal
 received by the antenna portion 201, a frequency conversion circuit 208
 converting the frequency of the output signal of the PLL circuit 207,
 receiving system circuits 206 to 208 receiving as input the standard time
 radio signal received by the antenna portion 201 and correcting the time
 of an internal clock according to a time code included in the received
 radio signal, transmission system circuits 206 and 210 to 212 generating a
 time radio signal including a time code based on the internal clock based
 on the output signal of the PLL circuit 207 or a signal converted in
 frequency by the frequency conversion circuit 208 and transmitting it at
 the time of transmission, and a selecting circuit 209 receiving as input
 the output signal of the PLL circuit 207 or a signal converted in
 frequency by the frequency conversion circuit 208 to an analog switch 210
 according to a selection signal SLC, so it is possible to selectively
 relay standard time radio signals having different modulation frequencies.
 As a result, there are the advantages that it is possible to correct the
 time based on a plurality of standard time radio signals without changing
 the radio correction clock side, reduce the cost, and realize a practical
 time correction system.
 Note that although the embodiment was explained with reference to an
 example of a configuration in which one frequency conversion circuit is
 provided, needless to say the present invention is not limited to this. It
 can also be applied to a variety of other embodiments, for example, one
 further providing another frequency conversion circuit having a different
 division ratio and switching between the two frequency conversion circuits
 according to the specifications.
 Further, since the control circuit 34 judges whether the received signal
 can be converted to time data or not, corrects the positions of the hands
 when possible, and informs the user that conversion is impossible by
 making the light emitting element 36 emit light, there is the advantage
 that it is possible to always recognize the state of reception of the
 radio signal at the time of operation.
 Summarizing the effects of the inventions, as explained above, according to
 the present invention, it is possible to selectively relay standard time
 radio signals having different modulation frequencies.
 As a result, it is possible to correct time based on a plurality of
 standard time radio signals without changing the radio correction clock
 side.
 While the invention has been described with reference to a specific
 embodiment chosen for purpose of illustration, it should be apparent that
 numerous modifications could be made thereto by those skilled in the art
 without departing from the basic concept and scope of the invention.