JP2002082187A - Electronic timepiece with wave reception function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio-controlled watch capable of receiving standard wave of a plurality of stations, having a simple constitution. SOLUTION: By turning on and off a frequency selection switch, turning over the parallel connection number of tuning capacity and varying capacitance value, the tuning frequency is controlled. By making the electric potential at one end of antenna to be the same as the electric potential at on-time of the frequency selection switch on the other hand, the frequency of a local circuit is selected as an electric potential at the on-time of the frequency selection switch from the control terminal of an electronic frequency selection means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electronic timepiece with a radio wave receiving function.

[0002]

2. Description of the Related Art In recent years, with the remarkable development of semiconductor technology and microcomputer circuit technology and an increase in the frequency band used, superheterodyne receiver circuits have been developed. Most of the receivers, except for mobile phones typified by mobile phones, TVs, car radios, portable radios, and other low-priced ones, use digital tuning superheterodyne electronic frequency selective receivers. Has become. As an example of the electronic frequency selective receiver, a PL made by SONY is available.
L SYNTHESIZED RECEIVERICF
-SW1, and the ICF-SW1 can input frequency data numerically with a tuning switch and can be used very conveniently.

Here, a conventional electronic frequency selective receiver will be described with reference to FIG. FIG. 2 is a block diagram of a conventional electronic frequency selective receiver. Reference numeral 1 denotes an antenna having one end connected to VDD, which is a power supply plus potential, to capture a radio signal and generate a reception signal Ss. Reference numeral 2 denotes a tuning circuit, which includes a variable capacitance diode 2a whose capacitance value can be controlled by a voltage level between the anode and the cathode, and a tuning capacitance 2b, wherein the variable capacitance diode 2a and the tuning capacitance 2b are connected in series. The antenna 1 is connected in parallel. The antenna 1 is tuned to the tuning frequency f1, which is the receiving frequency, based on the inductance value of the antenna 1 and the capacitance value of the tuning circuit 2. Reference numeral 3 denotes a frequency conversion circuit which receives the received signal Ss as an input, mixes the received signal Ss with another local oscillation signal LO, converts the frequency, and outputs an intermediate frequency signal IF which is a signal of an intermediate frequency f3. Intermediate frequency signal I from frequency conversion circuit 3
This is a demodulation circuit that receives and detects F and outputs a demodulated signal DM. Reference numeral 5 denotes a local oscillation circuit, which includes a coil 5a, a variable capacitance diode 5b whose capacitance value can be controlled by a voltage level between an anode and a cathode, a capacitor 5c, and the coil 5a, the variable capacitance diode 5b, and a capacitor 5c. And an oscillating unit 5d that oscillates according to the tank constant of the tank circuit to be operated. The coil 5a has one end connected to VDD and one end connected to the oscillation unit 5d,
The variable capacitance diode 5b and the capacitor 5c are connected in parallel with the coil 5a in a state of being connected in series. The oscillating unit 5d outputs a local oscillation signal LO oscillated according to the tank constant of the tank circuit. The frequency conversion circuit 3, the demodulation circuit 4, and the local oscillation circuit 5 constitute a superheterodyne receiving circuit 10. Reference numeral 6 denotes an electronic frequency selection means, which receives VSS as a reference voltage VDD as a frequency selection signal S1, selects frequency data based on its logic level, outputs a control signal VC corresponding to the frequency data, and outputs the control signal VC. By inputting the emission signal LO, the control signal VC is stabilized according to the frequency data. Reference numeral 7 denotes a frequency selection means, a frequency selection switch 7a having one end connected to VDD and one end connected to the control terminal C of the electronic frequency selection means 6, and one end connected to VSS which is a power supply minus potential, and one end selected for frequency. It is composed of a pull-down resistor 7b connected to the switch 7a. A speaker 8 converts the demodulated signal DM into an audible signal.

Next, the operation of the conventional electronic frequency selective receiver will be described with reference to FIG. For example, when the frequency selection switch 7a of the frequency selection means 7 is ON, the frequency selection signal S1 goes to the VDD level via the frequency selection switch 7a. At this time, the electronic frequency selection means 6 selects the frequency data D1 from the logic level of the frequency selection signal S1, and generates a control signal VC according to the frequency data D1. The control signal VC is supplied to the anode of the variable capacitance diode 5b of the local oscillation circuit 5, and the capacitance of the variable capacitance diode 5b is determined by the potential difference between VDD supplied to the cathode and control signal VC supplied to the anode. . From the tank constant of the variable capacitance diode 5b, capacitor 5c and coil 5a, the local oscillation circuit 5
Is determined and output as the local oscillation signal LO.
Here, the electronic frequency selection means 6 outputs the local oscillation signal LO.
Is input, the frequency of the local oscillation signal LO is compared with the frequency data D1, and if the frequency f of the local oscillation signal LO is
2 is lower than the frequency of the frequency data D1, the potential of the control signal VC is lowered to control the potential difference between the cathode and the anode of the variable capacitance diode 5b so as to decrease the capacitance value and to reduce the capacitance value. 5 is controlled to increase. If the frequency f2 of the local oscillation signal LO is higher than the frequency of the frequency data D1, the potential of the control signal VC is increased to control the potential difference between the cathode and the anode of the variable capacitance diode 5b so as to reduce the capacitance value. Is controlled so that the oscillation frequency of the local oscillation circuit 5 decreases. As described above, the local oscillation frequency f2 of the local oscillation signal LO of the local oscillation circuit 5 is controlled so as to be consistent with the frequency data D1 of the electronic frequency selection means 6 and to be stabilized. Can supply. The control signal VC is also supplied to the anode of the variable capacitance diode 2a of the tuning circuit 2. The variable capacitance diode 2a has a potential difference between the cathode at the VDD potential level and the anode at the potential level of the control signal VC. The tuning frequency f 1 is determined by the capacitance value of the tuning capacitor 2 b adjusted in advance and the inductance of the antenna 1.
Here, the local oscillation frequency f2 of the local oscillation signal LO and the tuning frequency f1 always have the following relationship with the intermediate frequency f3. f
3 = f2-f1. Therefore, the tuning frequency f1 depends on the frequency data D1.

The radio signal of the tuning frequency f1 efficiently received by the antenna 1 and the tuning circuit 2 is input to the frequency conversion circuit 3 as a reception signal Ss. The received signal Ss is frequency-converted by the frequency conversion circuit 3 at the frequency f2 of the local oscillation signal LO, output as the intermediate frequency signal IF at the intermediate frequency f3, and is demodulated by the demodulation circuit 4 designed exclusively for detection of the intermediate frequency f3. And is output as a demodulated signal DM. This is a feature of the superheterodyne receiving circuit 10 having excellent demodulation performance. The demodulated signal DM is generated as an audible signal by the speaker 8.

As described above, in the conventional electronic frequency selection receiver, the reception frequency tuning can be automatically performed by switching the frequency selection switch 7a which is easy to operate, and the local oscillation circuit 5 which is very accurate and stable can be obtained. By preparing
Superheterodyne receiving circuit 10 with excellent demodulation performance
Has been realized.

[0007]

As described above, in the conventional electronic frequency selective receiver, the tuning circuit 2 is constituted by the variable capacitance diode 2a. However, since the variable capacitance diode 2a is a semiconductor capacitance, there is a problem that the Q at the time of resonance is reduced and the efficiency of the antenna 1 is reduced. Further, since the variable capacitance diode 2a has a small capacitance value and its variable capacitance range is determined, there is a problem that the determination of the inductance of the antenna 1 is largely limited by the reception frequency range.

For example, in an electronic frequency selective receiver capable of receiving long standard radio waves in Japan and the United Kingdom, Japan's JG2
AS has a transmission frequency of 40 kHz and British MSF has a transmission frequency of 60 kHz. Therefore, the frequency of the radio wave is low, and the inductance value of the antenna 1 and the capacitance value of the tuning circuit 2 increase. At this time, since the transmission frequency ratio between Japan and the United Kingdom is 1.5 times, if the variable capacitance range of the variable capacitance diode 2a cannot be made large, the inductance value of the antenna 1 will increase. For this reason, the antenna 1 naturally becomes large, which greatly restricts the miniaturization of the receiver.

An object of the present invention is to solve the above problems and to provide an electronic timepiece that can receive a plurality of radio waves with a simple configuration.

[0010]

In order to achieve the above object, the present invention provides a receiving means for receiving a radio signal including time information, and a time display for displaying time based on the time information received by the receiving means. A time switch provided in the electronic timepiece, the time display means displaying time information obtained from a radio signal having the first frequency when the switch is in a first state. When the switch is in the second state, the time display means displays time information obtained from a radio signal having a second frequency.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a radio-controlled timepiece showing an embodiment of an electronic frequency selective receiver according to the present invention. The same elements as those of the conventional example shown in FIG. A tuning circuit 12 includes a fixed tuning capacitor 12a, a tuning capacitor 12b for selective connection, and a frequency selection switch 12c. The tuning capacitor 12a is connected in parallel to the antenna 1, and the tuning capacitor 12b and the frequency selection switch 12c are connected in parallel to the antenna 1 in a state of being connected in series. The connection point between the tuning capacitor 12b and the frequency selection switch 12c is connected to the control terminal C of the electronic frequency selection means 6 and to the reference potential VSS via the pull-down resistor 13a.

As described above, the frequency selection switch 1
2c is connected between VDD which is a reference potential and the tuning capacitor 12b, and the connection point is connected to the control terminal C of the electronic frequency selecting means 6, so that the frequency selecting switch 12c and the pull-down resistor 13a The selecting means 13 is constituted. That is, when the frequency selection switch 12c is in the OFF state, the pull-down resistor 13
The frequency selection signal S1 is at the VSS level via a, and when the frequency selection switch 12c is turned on, the frequency selection signal S1 is switched to the VDD level via the frequency selection switch 12c. The electronic frequency selection means 6 can be selected in accordance with the levels of the two reference potentials. That is, when the frequency selection signal S1 is VSS, the UK MSF can be received, and when the frequency selection signal S1 is Vs
When switching to DD, it can be selected so that JG2AS in Japan can be received. The pull-down resistor 13
By increasing the value of a, the reception signal Ss leaking through the tuning capacitor 12b when the frequency selection switch 12c is turned off should be minimized.

Reference numeral 14 denotes a detection signal D output from the demodulation circuit 4.
A decoding circuit that inputs M and decodes the time code outputs a time code signal TM. 15 is the decoding circuit 14
Is time display means for displaying the output time code signal TM as time data.

Next, the operation of the radio-controlled timepiece of the embodiment will be described. First, the reception operation of JG2AS in Japan will be described. When the frequency selection switch 12c of the frequency selection means 13 is turned on, the frequency selection signal S1 goes to the VDD level, and the watch enters the Japan mode. At this time, the electronic frequency selection means 6 selects Japanese frequency data D140 from the logic level of the frequency selection signal S1. And the frequency data D
140, a control signal VC is generated.
C is supplied to the anode of the variable capacitance diode 5b of the local oscillation circuit 5, and the variable capacitance diode 5b determines the capacitance value according to the potential difference between the cathode and the anode which is VDD. From the tank constant of the capacitor 5c and the coil 5a,
The oscillation frequency of the local oscillation circuit 5 is determined and the frequency is 140 kHz.
The signal is output as the local oscillation signal LO of z. Here, the electronic frequency selection means 6 inputs the local oscillation signal LO, the frequency of the local oscillation signal LO is compared with the frequency data D140, and if the local oscillation frequency of the local oscillation signal LO is
If the frequency is lower than 140, the potential of the control signal VC is lowered, the potential difference between the cathode and the anode of the variable capacitance diode 5b is increased, and the control is performed such that the capacitance value is reduced and the oscillation frequency of the local oscillation circuit 5 is increased. . If the local oscillation frequency of the local oscillation signal LO is higher than the frequency of the frequency data D140, the potential of the control signal VC is increased, the potential difference between the cathode and the anode of the variable capacitance diode 5b is reduced, and the capacitance value is increased. Control is performed so that the oscillation frequency of the oscillation circuit 5 becomes low. In this way, the local oscillation frequency of the local oscillation signal LO of the local oscillation circuit 5 is controlled so as to be consistent with the frequency data D140 of the electronic frequency selection means 6, and becomes a signal with a very high frequency accuracy of 140 kHz. At this time, since the frequency selection switch 12c of the frequency selection means 13 is ON, the tuning capacitance 12a and the tuning capacitance 12b are connected in parallel, and the total capacitance value of the tuning capacitance 12a and the tuning capacitance 12b, The tuning frequency of 40 kHz is determined by the inductance.

A radio signal having a tuning frequency of 40 kHz efficiently received by the antenna 1 and the tuning means 12 is:
The received signal Ss is input to the frequency conversion circuit 3. The received signal Ss is frequency-converted by the frequency conversion circuit 3 at the local oscillation frequency 140 kHz of the local oscillation signal LO, output as the intermediate frequency signal IF having an intermediate frequency of 100 kHz, and is demodulated exclusively for detection of the intermediate frequency 100 kHz. The signal is detected by the circuit 4 and output as a demodulated signal DM. The demodulated signal DM is decoded by the decoding circuit 14 into a time code signal TM, and the time code signal TM is displayed as time data by time display means 15.

Next, the receiving operation of the UK MSF will be described. The frequency selection switch 12 of the frequency selection means 13
When c is turned off, the frequency selection signal S1 goes to the VSS level via the pull-down resistor 13a, and the clock enters the UK mode. At this time, the electronic frequency selection means 6 selects British frequency data D160 from the logic level of the frequency selection signal S1. And the frequency data D1
A control signal VC is generated in accordance with the control signal VC.
Is supplied to the anode of the variable capacitance diode 5b of the local oscillation circuit 5, and the variable capacitance diode 5b determines the capacitance value according to the potential difference between the cathode and the anode, which is VDD, from the tank constant between the capacitor 5c and the coil 5a.
The oscillation frequency of the local oscillation circuit 5 is determined and the frequency is 160 kHz.
The signal is output as the local oscillation signal LO of z. Here, the electronic frequency selection means 6 inputs the local oscillation signal LO, the frequency of the local oscillation signal LO is compared with the frequency data D160, and if the local oscillation frequency of the local oscillation signal LO is
If the frequency is lower than 160, the potential of the control signal VC is lowered, the potential difference between the cathode and the anode of the variable capacitance diode 5b is increased, and the control is performed so that the oscillation value of the local oscillation circuit 5 is increased by reducing the capacitance value. . If the local oscillation frequency of the local oscillation signal LO is higher than the frequency of the frequency data D160, the potential of the control signal VC is increased, the potential difference between the cathode and the anode of the variable capacitance diode 5b is reduced, and the capacitance value is increased to increase the local capacitance. Control is performed so that the oscillation frequency of the oscillation circuit 5 becomes low. As described above, the local oscillation frequency of the local oscillation signal LO of the local oscillation circuit 5 is controlled so as to be consistent with the frequency data D160 of the electronic frequency selection means 6, and becomes a signal with a very high frequency accuracy of 160 kHz. At this time, since the frequency selection switch 12c of the frequency selection means 13 is OFF, the tuning capacitance 12b
, The VDD side is separated, and the tuning frequency of 60 kHz is determined by the capacitance value of the tuning capacitor 12 a and the inductance of the antenna 1.

A radio signal having a tuning frequency of 60 kHz efficiently received by the tuning means 12 at the antenna 1 is:
The received signal Ss is input to the frequency conversion circuit 3. The received signal Ss is frequency-converted by the frequency conversion circuit 3 at the local oscillation frequency 160 kHz of the local oscillation signal LO, output as the intermediate frequency signal IF having an intermediate frequency of 100 kHz, and is demodulated exclusively for detection of the intermediate frequency 100 kHz. The signal is detected by the circuit 4 and output as a demodulated signal DM. The demodulated signal DM is decoded by the decoding circuit 14 into a time code signal TM, and the time code signal TM is displayed as time data by time display means 15.

Therefore, in the radio-controlled timepiece of the embodiment, the tuning capacity 12a and the tuning capacity 12
For b, a fixed capacitor that can provide a high Q resonance without being limited by the semiconductor capacitor can be used, and the variable capacitance value is also determined by the tuning capacitor 12b. The design value of the inductance value also increases.

FIG. 3 is a block diagram of the tuning circuit 22, the antenna 1, and the frequency selecting means 13 showing an embodiment in which the position of the tuning capacitance and the frequency selection switch are changed with respect to FIG. 1, and the tuning circuit 22 is fixed. Tuning capacitor 22a, tuning capacitor 22b for selective connection, and frequency selection switch 22c
It is composed of The tuning capacitor 22a is connected in parallel to the antenna 1, and the tuning capacitor 22b and the frequency selection switch 22c are connected in parallel to the antenna 1 in a state of being connected in series. That is, in FIG.
2b is connected to a reference potential VDD, and a connection point between the tuning capacitor 22b and the frequency selection switch 22c is connected to a control terminal C of the electronic frequency selection means 6 and to a reference potential VSS via a pull-down resistor 13a. It is connected. The tuning capacitor 22b is connected to the reference potential VD
D and the frequency selection switch 22c, and by connecting the connection point to the control terminal C of the electronic frequency selection means 6, the frequency selection switch 22c
And the pull-down resistor 13a constitute the frequency selection means 13. That is, the frequency selection switch 22c is turned off.
In this state, the frequency selection signal S1 is at the VSS level via the pull-down resistor 13a, and when the frequency selection switch 22c is turned on, the frequency selection signal S1 is output via the antenna 1 and the frequency selection switch 22c. Since the level is switched to the VDD level, the electronic frequency selection means 6 can be selected in accordance with the two selected reference potential levels,
A function equivalent to that of the tuning circuit 12 shown in FIG. 1 is performed.

[0020]

As described above, since the electronic timepiece with the radio wave receiving function of the present invention is configured to select the receiving frequency by the switch, it is possible to provide an electronic timepiece capable of receiving a plurality of radio waves with a simple configuration. A great effect can be exhibited in a wristwatch or the like where miniaturization is desired as much as possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electronic frequency selective receiver according to the present invention.

FIG. 2 is a block diagram showing a conventional electronic frequency selective receiver.

FIG. 3 is a block diagram showing a component circuit of the electronic frequency selective receiver of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna 2, 12 Tuning circuit 3 Frequency conversion circuit 4 Demodulation circuit 5 Local oscillation circuit 6 Electronic frequency selection means 7a, 12c, 22c Frequency selection switch 15 Time display means

Claims (3)

[Claims] 1. An electronic timepiece having a radio wave receiving function, comprising: a receiving means for receiving a radio signal including time information; and a time display means for displaying time based on the time information received by the receiving means. A switch for switching the frequency of the radio wave is provided, and when the switch is in the first state, the timepiece is in the first mode, and the time display means displays time information obtained from a radio signal having the first frequency; An electronic timepiece with a radio wave receiving function, wherein the timepiece is in a second mode when the switch is in the second state, and the time display means displays time information obtained from a radio signal having a second frequency. 2. The electronic timepiece with a radio wave reception function according to claim 1, wherein the switch is a switch for switching a tuning capacity of an antenna for receiving the radio wave signal. 3. The receiving means has a local oscillation circuit and a frequency selection circuit for controlling an oscillation frequency of the local oscillation circuit,
The frequency selection circuit controls the local oscillation circuit to oscillate at a third frequency when the switch is in the first state, and oscillates at a fourth frequency when the switch is in the second state. The electronic timepiece with a radio wave receiving function according to claim 1.