JP4587820B2 - Radio clock - Google Patents

Description

  The present invention relates to a radio-controlled timepiece, and is particularly mounted in an automobile, receives standard radio waves in a plurality of different frequency bands, extracts time information from the received standard radio waves, and measures time based on the extracted time information. The present invention relates to a radio clock that corrects the time.

  In Japan, a standard radio wave JJY is transmitted in order to inform the domestic and foreign countries of time and frequency standards and Japan Standard Time (JST) based on Coordinated Universal Time (UTC). The standard radio wave JJY is obtained by superimposing a time code on a carrier wave having a frequency of 40 kHz or 60 kHz. The standard time is acquired by detecting this time code.

  The time code superimposed on the standard radio wave will be described.

  The time code is configured such that one cycle is 60 seconds and one pulse signal is included in one second. Position markers “P”, symbols “0”, and “1” are represented according to the pulse width. The position marker “P” is represented by a pulse having a pulse width of 0.2 s ± 5 ms. The code “0” is expressed by a pulse having a pulse width of 0.8 s ± 5 ms. Further, the symbol “1” is expressed by a pulse having a pulse width of 0.5 s ± 5 ms.

  As the time code, three codes of “0”, “1”, and “P” are determined based on the pulse width. At this time, conventionally, for example, as shown in FIG. 1, the time width between the edges of the pulse is detected to determine the sign (Patent Document 1).

  Such a radio timepiece receives a standard radio wave as a standard of time and frequency, detects the standard time, and adjusts the display time of the timepiece. This radio timepiece is currently used for a wall clock or a wristwatch.

  When a radio timepiece is mounted on an automobile, noise generated by the mounted electronic device or engine is large, and it is difficult to receive a standard radio wave in a normal state. In addition, since the ambient temperature fluctuates greatly in an automobile, the sensitivity of a receiving circuit for receiving standard radio waves has changed greatly, making reception difficult. For this reason, a radio timepiece mounted on an automobile or the like has received a standard radio wave and corrected the current time when the automobile engine is stopped, such as when the accessory switch is off.

See JP 2001-108770 A

  Further, since the conventional on-vehicle radio-controlled timepiece sometimes moves between a region having a frequency of 40 kHz and a region having a frequency of 60 kHz, it has been necessary to appropriately switch the reception frequency to a frequency at which reception is easy.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a radio timepiece that can reliably receive a standard radio wave regardless of location.

  The present invention is mounted on an automobile, receives a standard radio wave in one of two different frequency bands, extracts time information from the standard radio wave, and based on the extracted time information In a radio-controlled timepiece that corrects the time of day, a detection unit that detects that the accessory switch is turned off, and after the detection unit detects that the accessory switch is turned off, one of two frequency bands depending on the time of day Receiving frequency control means for switching the receiving frequency so as to alternately receive standard radio waves in one frequency band.

  The reception frequency control means receives a standard radio wave in one of the two frequency bands when the time information is an even number in the time measurement time, and receives two frequency bands in the time information when the time information is an odd number in the time measurement time. The reception frequency is switched so as to receive the standard radio wave in the other frequency band.

  The reception frequency control means is characterized in that the time for switching the reception frequency is shifted by a certain time every day.

  The reception frequency control means is characterized in that the time for switching the reception frequency is shifted by an odd time every day.

  The reception frequency control means switches the reception frequency band by switching the antenna.

  According to the present invention, after it is detected that the accessory switch has been turned off, the reception frequency is switched so as to receive the standard radio wave in one of the two frequency bands according to the time measurement time. Since standard radio waves can be received in both frequency bands, standard radio waves can be reliably received regardless of the location. In addition, since the reception frequency band is switched according to the clock time, switching can be performed with simple logic.

[First embodiment]
FIG. 1 shows a block diagram of a first embodiment of the present invention.

  The radio-controlled timepiece 100 of this embodiment is mounted on an automobile, receives standard radio waves in two different frequency bands f1 (= 40 kHz) and f2 (= 60 kHz), extracts time information from the standard radio waves, This is a timing device that corrects the timing based on the extracted time information, and mainly includes a first antenna 111-1, a second antenna 111-2, a switching circuit 112, an amplifier circuit 113, a filter 114, a detection circuit 115, and a control. The circuit 116 includes an AGC circuit 117, a display device 118, and an accessory switch 119.

  The first antenna 111-1 and the second antenna 111-2 are so-called bar antennas in which a copper wire is wound around a ferrite core, for example, and the first antenna 111-1 is tuned to a radio wave in a frequency band of 40 kHz. To generate a signal in the winding. The second antenna 111-2 is tuned to a radio wave in the 60 kHz frequency band and generates a signal in the winding. The signal generated by the first antenna 111-1 and the signal generated by the second antenna 111-2 are supplied to the switching circuit 112. The switching circuit 112 selectively outputs either a signal generated by the first antenna 111-1 or a signal generated by the second antenna 111-2 in response to the frequency switching signal from the control circuit 116. The signal output from the switching circuit 112 is supplied to the amplifier circuit 113.

  The amplifier circuit 113 is composed of a variable gain amplifier circuit. The gain is controlled in accordance with the AGC signal supplied from the AGC circuit 117, and the signal supplied from the switching circuit 112 is amplified so that the amplitude is constant. To do. The signal amplified by the amplifier circuit 113 is supplied to the filter 114.

  The filter 114 is composed of a low-pass or band-pass filter, and removes unnecessary components from the signal supplied from the amplifier circuit 113. The signal from which unnecessary components have been removed by the filter 114 is supplied to the detection circuit 115.

  The detection circuit 115 detects the signal supplied from the filter 114. The signal detected by the detection circuit 115 is supplied to the control circuit 116.

  The control circuit 116 compares the level of the signal supplied from the detection circuit 115 with a threshold level, detects whether it is a high level or a low level, and sets “0”, “0” based on the detected high level or low level time. Three types of codes “1” and “P” are recognized, and time information is extracted based on the recognized codes. The control circuit 116 keeps the current time internally and supplies the current time information being timed to the display device 118. The display device 118 is driven based on the current time information supplied from the control circuit 116, and performs display based on the current time information. Note that the display device 118 is driven to display, for example, when the accessory switch 119 is turned on. The accessory switch 119 is a switch that is turned on before the ignition switch is turned on when an automobile key is operated. Before the ignition switch is turned on, the accessory switch 119 is attached to various electrical devices such as meters and watches mounted on the car. It is a switch for supplying power.

  In addition, the control circuit 116 corrects the current time measured internally by the extracted time information. As a result, the current time measured by the control circuit 116 is corrected to be standard time information extracted from the standard radio wave, and a time very close to the standard time can be displayed on the display device 118.

  At this time, when the accessory switch 119 is turned off, the control circuit 116 sets the reception frequency so as to receive the standard radio wave in one of the two frequency bands of 40 kHz or 60 kHz according to the current time measurement time. Switch. For example, when the time information is even, 2 o'clock, 4 o'clock, 6 o'clock ... 24 o'clock in the current time, one of the two frequency bands, for example, a standard radio wave of 40 kHz is received, and the current time When the time information is odd, 1 o'clock, 3 o'clock, 5 o'clock, ... 23:00, the reception frequency is switched so that the other frequency band of the two frequency bands, for example, 60 kHz, is received .

  Next, the processing operation of the control circuit 116 will be described. Here, an embodiment will be described in which the output having the larger electric field strength is selected from the first antenna 111-1 and the second antenna 111-2.

  FIG. 2 shows a processing flowchart of the receiving operation by the control circuit 116.

  When the accessory switch 119 is turned off in step S1-1, the control circuit 116 acquires the current time information timed in step S1-2.

  Next, the control circuit 116 determines whether or not the time is an even number, that is, 2 o'clock, 4 o'clock, 6 o'clock, 8 o'clock,. When the time is an even number in the current time information acquired in step S1-3, the control circuit 116 switches the switching circuit 112 so that the output signal of the first antenna 111-1 is selected in step S1-4.

  Further, when the time is an odd number in the current time information acquired in step S1-3, that is, 1:00, 3:00, 5:00, 7:00,. The switching circuit 112 is switched so that the output signal of the second antenna 111-2 is selected.

  FIG. 3 is a diagram for explaining the operation of the first embodiment of the present invention.

  According to the present embodiment, the output signal of the first antenna 111-1 in the state where the accessory switch 119 is off at an even time of 2:00, 4:00, 6:00, 8:00,. When the standard radio wave in the frequency band of 40 kHz is received and the accessory switch 119 is off at an odd time of 1, 3, 5, 5, 7... 23, an output signal of the second antenna 111-2, A standard radio wave having a frequency band of 60 kHz is received.

  As a result, the standard radio wave can be received both when the vehicle exists in the area of the standard radio wave of 40 kHz and when the vehicle exists in the area of the standard radio wave of 60 kHz.

[Second Embodiment]
The configuration of the radio timepiece 200 of this embodiment is the same as that of the radio timepiece 100 of the first embodiment shown in FIG. 1, and only the processing of the control circuit 116 is different. Therefore, the description of the configuration is omitted. ,
FIG. 4 shows a processing flowchart of the receiving operation by the control circuit 116 of the second embodiment of the present invention.

  When the accessory switch is turned off in step S2-1, the control circuit 116 acquires current time information in step S2-2. Next, the control circuit 116 determines whether or not the switching time for switching the reception frequency has come in step S2-3. The switching time is set to “0′00 ″” at each time, for example, from 1 to 24:00.

  When it is determined in step S2-3 that it is the switching time, the control circuit 116 changes the date information of the current time information acquired in step S2-4 to the current time information acquired last time. It is determined whether or not it has been done. If the control circuit 116 determines in step S2-4 that the date has not been changed with respect to the previous current time information, the control circuit 116 controls the switching circuit 112 in step S2-5 to select the currently selected antenna. Switch. For example, when the output signal of the first antenna 111-1 is selected, the output signal of the second antenna 111-2 is selected and the output signal of the second antenna 111-2 is selected. Is switched so that the output signal of the first antenna 111-1 is selected.

  Further, the control circuit 116 does not switch the antenna when the current time information acquired in step S2-4 is changed with respect to the current time information acquired last time.

  Next, when the control circuit 116 receives the standard radio wave in step S2-6 and can acquire the standard time information in step S2-7, the control circuit 116 corrects the current time in step S2-8 and returns to step S2-2. And continue processing. If the standard time information cannot be acquired in step S2-7, the control circuit 116 returns to step S2-2 and continues the process without correcting the current time.

  FIG. 5 is a diagram for explaining the operation of the second embodiment of the present invention.

  According to the present embodiment, the reception antenna used for the odd time and the even time is switched every day. For example, the second antenna 111-2 is selected at 2 o'clock, 4 o'clock, 6 o'clock ... 24 o'clock, and the first antenna 111-1 is received at 1 o'clock, 3 o'clock, 5 o'clock ... 23 o'clock. Is selected, when the date changes, the second antenna 111-2 is selected at the reception time of 1 o'clock, 3 o'clock, 5 o'clock ... 23:00, the reception time of 2 o'clock, 4 o'clock, 6:00... The first antenna 111-1 is selected at 24:00.

  As described above, a fixed antenna is used at a fixed time, that is, it is possible to prevent reception of a standard radio wave at a fixed reception frequency at a fixed time.

[Modification]
In this embodiment, the reception time is switched every day between the time for receiving the standard radio wave by the first antenna 111-1 and the time for receiving the standard radio wave by the second antenna 111-2 between the odd time and the even time. However, in the operation of switching the reception frequency every hour, an antenna switching operation occurs every hour. For this reason, when an antenna switching operation occurs, there is a possibility that normal reception cannot be performed due to noise due to the antenna switching operation. For example, if the antenna switching operation is performed every hour, the reception operation cannot be performed for 24 minutes a day.

  In this modification, in order to reduce the time during which reception is not possible, the switching time of the second embodiment is set so that the antenna switches every 3 hours, and the reception frequency is switched.

  FIG. 6 is an operation explanatory diagram of a modification of the second embodiment of the present invention.

  According to the present embodiment, since the antenna switching operation is performed every 3 hours, the antenna switching is performed 8 times a day, and thus the reception operation cannot be performed for 8 minutes per day indicated by x in FIG. In other words, the time during which reception is not possible can be reduced to one-third compared to when the antenna is switched every hour.

  In this modification, the antenna is switched every 3 hours. However, if the antenna is switched every 2 to 12 hours, the number of antenna switching operations can be reduced, and the number of times the standard radio wave cannot be received can be reduced.

[Others]
In the first and second embodiments, the reception frequency is switched by switching the antenna. However, the present invention is not limited to this as long as the reception frequency can be switched.

It is a block block diagram of 1st Example of this invention. 6 is a processing flowchart of a receiving operation by the control circuit 116. It is operation | movement explanatory drawing of 1st Example of this invention. It is a processing flowchart of the reception operation | movement by the control circuit 116 of 2nd Example of this invention. It is operation | movement explanatory drawing of 2nd Example of this invention. It is operation | movement explanatory drawing of the modification of 2nd Example of this invention.

Explanation of symbols

100, 200 radio wave clock 111-1 first antenna, 111-2 second antenna, 112 switching circuit 113 amplifier circuit, 114 filter, 115 detection circuit, 116 control circuit 117 AGC circuit, 118 display device, 119 accessory switch

Claims (5)

It is mounted on an automobile, receives a standard radio wave in one of two different frequency bands, extracts time information from the standard radio wave, and calculates a time measurement time based on the extracted time information. In the radio time signal to be corrected,
Detecting means for detecting that the accessory switch is turned off;
After detecting that the accessory switch is turned off by the detecting means , periodically acquiring current time information that is timed internally, and determining whether or not it is the switching time of the frequency band, When it is determined that the switching time of the frequency band has been reached, the reception is performed when it is determined that the date is not changed with respect to the current time information acquired last time in the current time information acquired at that time. A radio-controlled timepiece having a reception frequency control means for switching the frequency and not switching the reception frequency when it is determined that the date has been changed.   The reception frequency control means receives a standard radio wave of one frequency band of the two frequency bands when the time information is an even number in the time measurement time, and when the time information is an odd number in the time measurement time, The radio-controlled timepiece according to claim 1, wherein the reception frequency is switched so as to receive a standard radio wave in the other frequency band of the two frequency bands.   The radio wave timepiece according to claim 1, wherein the reception frequency control means shifts the switching time of the frequency band by a certain time every day.   4. The radio timepiece according to claim 3, wherein the reception frequency control means shifts the switching time of the frequency band by an odd time every day. The radio wave timepiece according to any one of claims 1 to 4 , wherein the reception frequency control means switches a reception frequency band by switching an antenna.

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