JP3889176B2 - Wireless control clock - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radio controlled timepiece.
[0002]
[Prior art]
A circuit configuration for a tunable resonant circuit having a plurality of switches that can be turned on and off independently by means of such a radio controlled watch or a switch of the electronic switch group is known from German Patent DE 4332798. In such known circuit configurations, the resonant circuit is excited in a balanced phase by an oscillator at its resonant frequency. In the balanced phase, the frequency comparator compares the oscillation frequency of the resonant circuit with a reference value determined by the resonant frequency, and if there is a frequency difference, the switch position of the above-mentioned switch is changed until the compared frequencies match. Is done. The detector detects the frequency match being compared and switches off the oscillator while achieving storage of the switch position.
[0003]
The microcontroller can automatically switch to the frequency received in each geographical reception area without user intervention.
[0004]
A radio-controlled timepiece having an antenna resonance circuit is known, for example, from US Pat. No. 5,331,608.
[0005]
[Problems to be solved by the invention]
The object of the present invention is to receive the reception frequency from other transmitters (eg, MSF and WWVB) having a given transmission frequency with a simple configuration as described in the introductory part of this specification. It is to provide a wireless control watch that can be used.
[0006]
[Means for Solving the Problems]
According to the invention, the object is achieved by the features of claim 1. Preferred embodiments of the radio controlled watch according to the invention are characterized by the appended claims.
[0007]
On the receiver side, a plurality of crystal oscillators for various desired frequencies are usually connected in parallel so that there is one or more frequency ranges and a filter pass or band range exists. The antenna switching operation establishes the reception frequency. This has the advantage that only one receiver is required and the circuit has a very high resistance so that there is no switching of the crystal oscillator in that it is sensitive to receiver problems.
[0008]
In the case of the radio controlled timepiece according to the present invention, the frequency is switched by appropriate switching of the capacitor of the antenna resonance circuit. In this case, a parallel circuit or series circuit of capacitors can be provided. As the switch, a junction FET, MOSFET, or transmission gate can be used. However, the switch can also be constituted by a relay, in particular a small reed relay. With such a small reed relay, it is possible to perform current separation (Galvanic separation) between the control circuit of the radio controlled timepiece and the antenna circuit with respect to signal interference.
[0009]
If the switch is composed of a junction FET or MOSFET or a transmission gate circuit, the gate-source voltage can be generated by a voltage conversion circuit that drives the FET, which reduces the on-resistance. As a result, the antenna input is substantially short-circuited, and during the switching operation from one transmission frequency to another, reception is blocked, so that buildup in the resonant circuit is prevented. Thus, the expected transient behavior or response is determined by the series resistance described above.
[0010]
The voltage conversion circuit of the radio controlled timepiece according to the present invention is preferably a bipolar transistor that switches off the FET again. The second capacitor is provided by the gate capacitance of the FET. The diode provided in the voltage conversion circuit may be a Schottky diode. It is possible and preferable to design an integrated voltage conversion circuit according to the invention and to apply it to a radio controlled watch according to the invention. The voltage conversion circuit may include one or more stages.
[0011]
In the case of the radio controlled timepiece according to the present invention, the antenna switching is preferably realized by an open drain in the microcontroller (μC).
[0012]
In the wireless control timepiece according to the present invention, when the switch is constituted by a relay or a small reed relay, it is preferable to use a bistable reed relay suitable for a low excitation current in the control winding.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The features and advantages of the main part of the wireless control timepiece according to the present invention will be apparent from the accompanying drawings and the following description.
[0014]
FIG. 1 is a block diagram showing an antenna resonance circuit 10 for a radio controlled watch such as a radio controlled wristwatch, which includes an antenna 12 and two capacitors 14 and 16 connected in series. The capacitor 16 is connected together with the switch 18. Capacitor 16 is switched to a circuit or shorted by switch 18.
[0015]
Switching of the resonance frequency of the antenna resonance circuit is used to change the tuning when interference or noise signal is generated, so that the resonance frequency of the antenna resonance circuit 10 falls within the range of remote selection of the receiver, or 2 It is possible to change arbitrarily between two resonant frequencies, ie between two different transmitter frequencies, for example between 77.5 and 60 kHz.
[0016]
The antenna resonance circuit 10 is connected together with a receiver 20 indicated by a block.
[0017]
FIG. 2 is a circuit diagram similar to that shown in FIG. 1 and shows a second configuration of the antenna resonance circuit 10 having the antenna 12 and the capacitors 14 and 16 connected in parallel to each other. The switch 18 is connected in series with the parallel arm of the capacitor 16, that is, the capacitor 16. Reference numeral 20 in FIG. 2 denotes a radio-controlled timepiece receiver, which is indicated by a block in the drawing.
[0018]
FIG. 3 is a circuit diagram similar to that shown in FIG. 2, shown with two capacitors 14, 16, blocks connected in parallel, together with the antenna 12 of the antenna resonant circuit 10 connected together to the receiver 20. Show. The connection switch 18 in series with the capacitor 16 is here formed by an FET 22 connected to a voltage conversion circuit 24. The voltage conversion circuit 24 includes a bipolar transistor 26, a diode 28, and a capacitor 30. The capacitor 32 can be arbitrarily provided. The diode 28 can take the form of a Schottky diode.
[0019]
The FET 22 is, for example, a P channel FET. For example, a pnp transistor 26 is connected to the gate of the FET.
[0020]
The capacitor 14 is associated with the antenna 12 which is a flexible antenna, for example. The capacitor 14 and the antenna 12 are tuned to a transmission frequency of 77.5 kHz, for example. This shows that the wireless control watch of the present invention can include a so-called standard DCF77 antenna. This is advantageous from a service point of view. This is because such antennas can be easily replaced in the service department. A second capacitor 16 associated with the switch 18 tunes the antenna resonant circuit 10 of the receiver 20 to a low frequency, for example 60 kHz.
[0021]
The second capacitor 16 or the first or main capacitor 14 can be formed by a combination of capacitors known per se. The antenna 12 is preferably in the form of a symmetric antenna in which the antenna capacitor 14 is changed by switching by the switch 18.
[0022]
The present invention does not require the use of a corresponding number of antennas tuned to each of the respective transmission frequencies for the various transmission frequencies, and thus there is no mutual interference in the antenna portion.
[0023]
In the circuit arrangement described above, the gate-source complete voltage for sufficiently driving the FET 22 is generated by the voltage conversion circuit 24, and the ON resistance becomes low. This prevents reception during the switching operation, thereby preventing a rise and establishing a predetermined transient characteristic or response.
[0024]
【The invention's effect】
According to the present invention, the frequency can be switched with a simple configuration by appropriately switching the parallel circuit or series circuit of the capacitor of the antenna resonance circuit.
[0025]
When the switch is composed of a junction FET or MOSFET or a transmission gate circuit, the gate-source voltage can be generated by a voltage conversion circuit that drives the FET, which reduces the on-resistance and substantially reduces the antenna input. During the switching operation from one transmission frequency to another, the reception is said to be blocked.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a first circuit configuration of an antenna resonance circuit having series-connected capacitors.
FIG. 2 is a circuit diagram showing a second circuit configuration of an antenna resonance circuit having a parallel connection capacitor.
3 is a circuit diagram showing a circuit configuration similar to FIG. 2; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Antenna resonance circuit 12 Antenna 14 Capacitor 16 Capacitor 18 Switch 20 Receiver 22 FET
24 voltage conversion circuit 26 bipolar switch 28 diode 30 capacitor 32 capacitor

Claims (8)

A radio controlled watch suitable for receiving different transmission frequencies from transmitters having various time characters,
An antenna resonant circuit having first and second capacitors and an antenna;
A switch connected in series or in parallel to the first and second capacitors,
A receiver having a plurality of crystal oscillators connected to the antenna resonance circuit and connected in parallel to the antenna resonance circuit has a transmission range of different transmission frequencies by switching the switch. Wireless control clock.   2. The radio controlled timepiece according to claim 1, wherein the switch has a junction FET, a MOSFET, a transmission gate or a relay.   3. The radio controlled timepiece according to claim 2, wherein the voltage conversion circuit is provided to generate a gate source voltage that sufficiently drives the FET.   4. The radio controlled timepiece according to claim 3, wherein the voltage conversion circuit includes a bipolar transistor for switching off the FET.   5. The radio controlled timepiece according to claim 3, wherein the voltage conversion circuit is in the form of an integrated circuit.   The radio controlled timepiece according to claim 2, wherein the relay is a reed relay.   The radio controlled timepiece according to claim 6, wherein the reed relay is a bistable type.   8. The radio controlled timepiece according to claim 1, wherein the antenna of the antenna resonance circuit has a symmetric characteristic.

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