Radio-controlled clock repeater

Abstract

To provide a radio-controlled clock repeater that can prevent an error when acquiring time information on the basis of the voltage waveform of a commercial AC power supply.SOLUTION: A host machine 1 comprises a host machine RTC 3 that counts time, and a host machine controller 8 that is connected with the host machine RTC 3. The host machine controller 8 calculates a count value A0 that is the difference between a first time value measured on the basis of the periodicity of a voltage waveform from a commercial AC power supply for every predetermined time T0 and a second time value measured by using the host machine RTC 3, calculates the average value of the plurality of count values A0 as a reference count value A1, corrects the time counted by the host machine RTC 3 so as to reduce a difference value A2 that is the difference between the count values A0 and the reference count value A1, and generates a time information signal on the basis of the time counted by the host machine RTC 3.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present disclosure relates to a radio-controlled clock repeater capable of outputting a pseudo standard radio wave toward a radio-controlled clock. [Background technology]

[0002] Patent Document 1 discloses a radio-controlled clock repeater that outputs a pseudo standard radio wave (hereinafter referred to as a pseudo standard radio wave) having the same specifications as a standard radio wave, toward a radio-controlled clock. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-183501 A [Patent Document 2] JP 2012-88202 A [Patent Document 3] JP 2007-327871 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the radio-controlled clock repeater disclosed in Patent Document 1 relays standard radio waves transmitted from a standard radio wave transmitting station. For this reason, this type of radio-controlled clock repeater cannot be used in environments where it is not possible to receive standard radio waves propagating outdoors, such as indoors that are isolated from the outside.

[0005] Meanwhile, various electronic devices obtain the current time using a real-time clock (RTC). A known method of correcting the current time of an RTC is to correct it based on the periodicity of the voltage waveform of a commercial AC power supply (Patent Documents 2 and 3). If such a method of correcting the current time is applied to a radio-controlled clock repeater, the radio-controlled clock repeater can generate a pseudo standard radio wave based on the accurate time, even in an environment where it cannot receive a standard radio wave.

[0006] However, time measured based on the voltage waveform of a commercial AC power supply fluctuates by about ±5 seconds. It can take as little as a few minutes or as long as a week for this fluctuation to return to 0 seconds. This fluctuation is caused by the balance between power supply and demand, and occurs when the generator's rotation speed changes and the power company adjusts the amount of power generated. For this reason, the fluctuation cannot be predicted and becomes a noise-like fluctuation. Therefore, if time information is obtained using the voltage waveform of a commercial AC power supply, the time will be accurate over the long term and the cumulative error will not increase, but there is a problem that an error of up to ±5 seconds will occur momentarily.

[0007] An object of the present invention is to provide a radio-controlled clock repeater that can suppress errors when acquiring time information based on the voltage waveform of a commercial AC power supply. [Means for solving the problem]

[0008] The present invention is a radio-controlled clock repeater comprising a parent unit that transmits a time information signal according to standard time, and a child unit that receives the time information signal from the parent unit and outputs a pseudo standard radio wave, wherein the parent unit comprises a parent unit real-time clock that keeps time, and a parent unit control means connected to the parent unit real-time clock, and the parent unit control means comprises a first time difference calculation means that calculates a first time difference, which is the difference between a first time value measured based on the periodicity of the voltage waveform from a commercial AC power source at every predetermined time and a second time value measured using the parent unit real-time clock, a reference time difference calculation means that calculates the average value of a plurality of first time differences as a reference time difference, a correction means that corrects the time kept by the parent unit real-time clock so that the difference between the first time difference and the reference time difference is reduced, and a time information signal generation means that generates the time information signal based on the time kept by the parent unit real-time clock. Effect of the Invention

[0009] According to the present invention, the parent control means corrects the time kept by the parent real-time clock so as to reduce the difference between the first time difference and the reference time difference, so that the time kept by the parent real-time clock tracks the reference time difference. As a result, it is possible to reduce the influence of fluctuations in the voltage waveform of the commercial AC power supply and suppress errors when time information is obtained based on the voltage waveform of the commercial AC power supply. [Brief description of the drawings]

[0010] [Figure 1] 1 is an overall configuration diagram showing a radio-controlled clock repeater according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a front view showing the parent unit in FIG. [Diagram 3] FIG. 2 is a block diagram showing the configuration of a parent unit. [Figure 4] 2 is a front view showing the slave unit in FIG. 1. [Diagram 5] FIG. 2 is a perspective view showing the handset mounted on a wall. [Figure 6] FIG. [Figure 7] FIG. 2 is a block diagram showing the configuration of a slave unit. [Figure 8] 11 is a flowchart showing standard radio wave data transmission processing by the master unit. [Figure 9] 11 is a flowchart showing a pseudo standard time radio wave transmission process by a slave unit. [Figure 10] 1 is a flowchart showing a parent RTC correction process. [Figure 11] 4 is a characteristic diagram showing an example of time variations in the error and feedback term of an AC signal. FIG. [Figure 12] FIG. 11 is a characteristic diagram showing an example of changes over time in the error of the parent RTC, the error of the AC signal, and the correction value of the parent RTC when the AC signal fluctuates by a maximum of about ±5 seconds. [Figure 13] FIG. 11 is a characteristic diagram showing an example of changes over time in the error of the parent RTC, the error of the AC signal, and the correction value of the parent RTC when the AC signal fluctuates by a maximum of about ±10 seconds. [Figure 14]FIG. 13 is a characteristic diagram showing an example of time variations in the error of the parent RTC, the error of the AC signal, and the correction value of the parent RTC in a case where the unit correction amount is set to half that of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a radio-controlled clock repeater according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that each step in the flow charts shown in Figures 8, 9, and 10 will be represented by the letter "S" (for example, step 1 will be represented by "S1").

[0012] 1 to 7 show a radio-controlled clock repeater according to an embodiment. The radio-controlled clock repeater includes a master unit 1 that transmits a time information signal (standard radio wave data) according to standard time, and a slave unit 11 that receives the time information signal from the master unit 1 and outputs a pseudo standard radio wave.

[0013] 1 and 2, the master unit 1 includes a box-shaped master unit casing 2. The master unit 1 also includes a master unit real-time clock 3 (hereinafter referred to as master unit RTC 3), a main power supply unit 4, a wireless module 5, and a master unit controller 8. The master unit RTC 3, the wireless module 5, and the master unit controller 8 are housed within the master unit casing 2. In addition, the master unit 1 includes a time setting unit 6 and a display unit 7.

[0014] As shown in Fig. 3, the master RTC 3 is configured using, for example, a crystal oscillator 3A, and keeps time. The master RTC 3 is connected to a master controller 8. Power is supplied to the master RTC 3 from a main power supply unit 4 via the master controller 8. Therefore, when the main power supply unit 4 is connected to a commercial alternating current power supply (commercial AC power supply), the master RTC 3 is driven by power supplied from the main power supply unit 4. The master RTC 3 obtains the current time based on the input initial time. The master RTC 3 outputs a signal corresponding to the current time to the master controller 8.

[0015] At this time, when the crystal oscillator 3A outputs a basic clock signal according to the oscillation frequency, the master RTC 3 counts the basic clock signal and measures time based on the count number. For example, if the reference oscillation frequency of the crystal oscillator 3A is 32768Hz, the master RTC 3 marks one second when the count number reaches 32769 times.

[0016] Moreover, the master RTC3 has a function (correction function) of adjusting the count number, for example, every 20 seconds, in order to correct the measured time. Specifically, the master RTC3 increases or decreases the count number itself per unit time (for example, 1 second) of the basic clock signal to correct the measured time. For example, if the reference oscillation frequency of the crystal oscillator 3A is 32768Hz, but the actual oscillation frequency is higher than the reference oscillation frequency, 32768.1Hz (=+3.05ppm), the master RTC3 increases the count value once every 20 seconds and counts 32770 times to tick one second. If the actual oscillation frequency of the crystal oscillator 3A is lower than the reference oscillation frequency, the master RTC3 decreases the count value once every 20 seconds according to the frequency error to tick one second. Note that the time interval for correcting the time of the master RTC3 is not limited to 20 seconds. The time interval for correcting the time of the master RTC 3 may be shorter or longer than 20 seconds depending on the specifications of the master RTC 3, etc.

[0017] The master RTC 3 holds the count number correction setting value (adjustment amount) and the increase / decrease information in a memory (not shown). Therefore, the master RTC 3 corrects the measurement time by updating the count number correction setting value and the increase / decrease information according to the time error.

[0018] The parent RTC 3 is also connected to a backup power source 3B, which may be a button battery, a capacitor, or the like. This allows the parent RTC 3 to continue to run on power from the backup power source 3B and keep time even when the power supply from the main power source 4 is temporarily stopped. Information such as correction settings is set at the time of manufacture at the factory, and is backed up by the backup power source 3B, just like the clock information of the parent RTC 3.

[0019] The main power supply unit 4 is connected to the parent controller 8. The main power supply unit 4 supplies power to the parent controller 8. The main power supply unit 4 includes a power adapter 4A, an AC-DC conversion circuit 4B, and a low-voltage power supply circuit 4C. The power adapter 4A is configured, for example, by a plug, and is connected to a commercial AC power outlet (not shown). The power adapter 4A supplies AC power from the commercial power supply to the AC-DC conversion circuit 4B. The AC-DC conversion circuit 4B is configured by various converter circuits and converts AC power into DC power. The low-voltage power supply circuit 4C converts the voltage of the DC power supplied from the AC-DC conversion circuit 4B to a constant low voltage (for example, 3.3V) required by the parent controller 8. The low-voltage power supply circuit 4C is configured, for example, by various DC-DC converter circuits. The low-voltage power supply circuit 4C supplies low-voltage DC power to the parent controller 8.

[0020] The main power supply unit 4 also includes an AC signal extraction circuit 4D. The AC signal extraction circuit 4D detects the AC voltage of the commercial power source output from the power adapter 4A, and outputs an AC signal corresponding to this AC voltage to the parent controller 8. At this time, the AC signal extraction circuit 4D constitutes a pulse conversion unit and converts the sine wave AC signal into a pulse signal. The parent controller 8 includes a pulse counter 8B that counts the pulse signal. The main power supply unit 4 is housed in the parent casing 2, except for the power adapter 4A. That is, the AC-DC conversion circuit 4B, the low voltage power supply circuit 4C, and the AC signal extraction circuit 4D are housed in the parent casing 2.

[0021] The wireless module 5 constitutes the parent device side communication section. The wireless module 5 of the parent device 1 performs wireless communication of LPWA (Low Power Wide Area-network) with the wireless module 23 of the child device 11. The wireless module 5 uses, for example, a LoRa communication method in the 920 MHz band. This makes the wireless module 5 relatively resistant to disturbances and capable of long-distance communication. The wireless module 5 transmits or receives radio waves in the 920 MHz band from an antenna (not shown). The use of radio waves in the 920 MHz band provides high reception sensitivity and is resistant to building walls, etc., enabling communication even in complex indoor spaces.

[0022] The time setting unit 6 is attached to the front of the parent unit casing 2. The time setting unit 6 is composed of, for example, a plurality of button switches, and is connected to the parent unit controller 8. The time setting unit 6 is used to set the initial time of the parent unit 1. Specifically, the time setting unit 6 has a switch for advancing and retreating the initial time. For example, when starting up the parent unit 1 for the first time, or when the parent unit 1 has not been turned on for a long period of time, the user sets the initial time of the parent unit 1 using the time setting unit 6.

[0023] The display unit 7 is attached to the front of the parent unit casing 2. The display unit 7 is composed of, for example, a seven-segment LED, a single-color chip LED, a full-color LED, or the like, and is connected to the parent unit controller 8. The display unit 7 displays, for example, the current time, the initial time, and the like. The display unit 7 lights up as an error indication when an abnormality occurs in the parent unit 1, etc.

[0024] The master controller 8 is configured with, for example, a microcomputer. The master controller 8 operates according to a program stored in memory 8A. The master controller 8 is connected to the master RTC 3, wireless module 5, time setting unit 6, display unit 7, etc. The master controller 8 corrects the time based on the master RTC 3 based on a voltage signal (AC signal) of a commercial alternating current power supply (commercial AC power supply).

[0025] The frequency of commercial AC power is controlled with high precision by the power company. Therefore, if the voltage signal of commercial AC power is used as the clock's oscillation circuit, there is no constant "error / month" as occurs with a quartz crystal oscillator, and the cumulative error can be maintained within the range of about ±5 seconds throughout the year. Therefore, from a long-term perspective, time management synchronized with AC power without using an RTC provides higher accuracy. Therefore, when the parent controller 8 is driven by commercial AC power, it executes the parent RTC correction process described below.

[0026] In the master RTC correction process, the master controller 8 corrects the time kept by the master RTC3 at intervals of a predetermined time T0, such as once every 15 minutes. At this time, the master controller 8 calculates the difference between the time measured based on the periodicity of the AC signal (first time value) and the time measured by the master RTC3 (second time value) at each predetermined time T0. The master controller 8 changes the correction setting value of the master RTC3 based on this time difference (time difference). This allows the master controller 8 to obtain accurate time information using the master RTC3.

[0027] The time interval (predetermined time T0) for correcting the time of the parent RTC 3 is not limited to 15 minutes. The predetermined time T0 may be 15 minutes or less, or may be 15 minutes or more. The predetermined time T0 is preferably 5 minutes, 10 minutes, 15 minutes, or 30 minutes, which is an integer fraction of 1 hour.

[0028] The master controller 8 is connected to a standard radio wave data setting circuit 9. The master controller 8 outputs accurate time information acquired using the master RTC 3 or the like to the standard radio wave data setting circuit 9. The standard radio wave data setting circuit 9 sets a time code that becomes the data of the pseudo standard radio wave based on the time information input from the master controller 8. The time code includes time information such as year, month, day, hour, and minute. The standard radio wave data setting circuit 9 outputs the set standard radio wave data (time code) to the master controller 8.

[0029] The master controller 8 is normally in a sleep state. The master controller 8 wakes up at a predetermined wake-up date and time D10 and waits for a call signal to arrive from the slave 11. When the master controller 8 receives a call signal from the slave 11, it establishes communication with the slave 11 and transmits standard radio wave data as a time information signal to the slave 11 using the wireless module 5.

[0030] As shown in Figures 4 to 6, the handset 11 includes a handset casing 12, a latch 13, and an adjuster mechanism 14. The handset casing 12 is formed in a flat plate shape having a predetermined thickness and is composed of a main body housing section 12A and a lid section 12B. The main body housing section 12A is formed in a rectangular box shape, for example, and is open on the front side. Inside the main body housing section 12A, a power supply section 22, a wireless module 23, a pseudo standard radio wave output section 24, a handset controller 30, etc., which will be described later, are housed.

[0031] The lid 12B is formed in a flat plate shape and is attached to the main body housing 12A by screwing or the like. The lid 12B is located on the front side of the main body housing 12A and covers the opening of the main body housing 12A. A window 12C is formed in the center of the lid 12B. The window 12C is formed of, for example, a rectangular through hole, and inside the window 12C, a power switch 22C, a display unit 25, a setting unit 26, an access switch 27, etc. are exposed.

[0032] The hanging device 13 is formed of a rectangular flat plate bent into an L-shape, and is attached to the upper part of the handset casing 12. A wall-hanging hole 13A, which is, for example, a pentagonal through-hole, is formed in the center of the hanging device 13. The tip of a hook-shaped mounting device F attached to, for example, a wall surface W of a building is inserted into a corner 13B located at the top of the wall-hanging hole 13A. In this way, the hanging device 13 fixes the handset 11 in a hanging state to the wall. A latch member 13C is attached to the hanging device 13. The latch member 13C is attached to holding portions 13D and 13E provided at both ends of the hanging device 13 in the left-right direction. The latch member 13C is located below the corner 13B of the wall-hanging hole 13A and extends in the left-right direction of the hanging device 13 across the wall-hanging hole 13A. The mounting fixture F fixed to the wall W is inserted into the wall-hanging hole 13A with the bar member 13C removed, and is fixed at the position of the corner 13B. This allows the bar member 13C to allow the mounting fixture F fixed to the wall (wall W) to be inserted into the corner 13B of the wall-hanging hole 13A. The bar member 13C is attached to the latch 13 after the mounting fixture F is inserted into the wall-hanging hole 13A. This prevents the mounting fixture F from coming off the slave unit 11 when the radio-controlled clock CLK is removed from the slave unit 11.

[0033] The adjuster mechanism 14 includes a rail member 14A, a spacer 14C, a slider 14D, and a mounting fixture 14E. The rail member 14A is located in front of the hook 13 and extends in the vertical direction. A guide hole 14B consisting of a long and narrow slit extending in the vertical direction is formed in the center of the rail member 14A. The rail member 14A is attached to the front side of the hook 13 via, for example, three spacers 14C. One spacer 14C is disposed at the upper end portion of the rail member 14A, and two spacers 14C are disposed at the lower end portion of the rail member 14A. The spacer 14C is interposed between the rail member 14A and the hook 13, so that the rail member 14A faces the hook 13 with a gap therebetween. A bar member 13C is inserted between the rail member 14A and the hook 13.

[0034] The slider 14D is composed of two plate-like members facing each other with the rail member 14A in between. The center portion of the slider 14D is inserted into the guide hole 14B of the rail member 14A. The position of the slider 14D can be shifted in the vertical direction along the guide hole 14B.

[0035] The base end of the mounting fixture 14E is inserted into the center of the slider 14D. The mounting fixture 14E is inserted into a wall hanging hole (not shown) of the radio-controlled clock CLK to support the radio-controlled clock CLK. The mounting fixture 14E is composed of a cylindrical rod portion and a disk portion formed at the tip of the rod portion and having a larger radial dimension than the rod portion. The mounting fixture 14E is formed, for example, from a metal material. The outer peripheral surface of the disk portion is knurled. The disk portion of the mounting fixture 14E serves as a retaining portion that prevents the radio-controlled clock CLK from falling off the mounting fixture 14E.

[0036] A bolt is formed at the base end of the rod-shaped portion of the mounting fixture 14E. When the disk portion of the mounting fixture 14E is rotated in the direction in which the bolt is tightened, the two plate-shaped members of the slider 14D are displaced in a direction approaching each other. As a result, the slider 14D is in a state in which the rail member 14A is sandwiched between the two plate-shaped members, and the slider 14D is restricted from being displaced in the up-down direction and is fixed in position.

[0037] When the disk portion of the mounting fixture 14E is rotated in the direction that loosens the bolt, the two plate-like members of the slider 14D are displaced in a direction away from each other, whereby the slider 14D is released from the state in which the rail member 14A is sandwiched between the two plate-like members, and becomes capable of displacement in the vertical direction.

[0038] 7, the slave 11 includes a slave real-time clock 21 (hereinafter referred to as slave RTC 21), a power supply unit 22, a wireless module 23, a pseudo standard radio wave output unit 24, and a slave controller 30. The slave RTC 21, the wireless module 23, the pseudo standard radio wave output unit 24, and the slave controller 30 are housed in the slave casing 12. In addition, the slave 11 includes a display unit 25 and a setting unit 26.

[0039] The slave RTC 21 is configured in a similar manner to the master RTC 3. For this reason, the slave RTC 21 is configured using, for example, a crystal oscillator 21A, and keeps time. The slave RTC 21 is connected to the slave controller 30. Power is supplied to the slave RTC 21 from the power supply unit 22 via the slave controller 30. For this reason, the slave RTC 21 is driven by the power supplied from the power supply unit 22. The slave RTC 21 obtains the current time based on the initial time input by a time setting unit (not shown) of the slave 11. The initial time of the slave RTC 21 does not necessarily have to be set by the slave 11, and may be set by the master 1 using communication between the master 1 and the slave 11. The slave RTC 21 outputs a signal according to the current time to the slave controller 30. Also, like the master RTC 3, the slave RTC 21 also has a built-in correction function for correcting errors.

[0040] At this time, when the crystal oscillator 21A outputs a basic clock signal according to the oscillation frequency, the slave RTC 21 counts the basic clock signal and measures time based on the count number. For example, if the reference oscillation frequency of the crystal oscillator 21A is 32768 Hz, the slave RTC 21 marks one second when the count number reaches 32769 times.

[0041] Moreover, the slave RTC 21 has a function of adjusting the count number, for example, every 20 seconds, in order to correct the measured time. Specifically, the slave RTC 21 increases or decreases the count number itself per unit time (for example, one second) of the basic clock signal to correct the measured time. For example, when the reference oscillation frequency of the crystal oscillator 21A is 32768 Hz and the actual oscillation frequency is higher than the reference oscillation frequency, the slave RTC 21 increases the count value once every 20 seconds according to the frequency error and ticks off one second. When the actual oscillation frequency of the crystal oscillator 21A is lower than the reference oscillation frequency, the slave RTC 21 decreases the count value once every 20 seconds according to the frequency error and ticks off one second. Note that the time interval for correcting the time of the slave RTC 21 is not limited to 20 seconds. The time interval for correcting the time of the slave RTC 21 may be shorter or longer than 20 seconds depending on the specifications of the slave RTC 21, etc.

[0042] At this time, the slave RTC 21 holds the correction set value (adjustment amount) of the count number and information on the increase / decrease. Therefore, the slave RTC 21 corrects the measurement time by updating the correction set value of the count number and the information on the increase / decrease in accordance with the time error. Information such as the correction set value is set at the time of manufacture at the factory, and like the clock information of the slave RTC 21, is backed up by power supplied from the power supply unit 22. Note that, like the master RTC 3, the slave RTC 21 may also be connected to a backup power source consisting of, for example, a button battery, a capacitor, or the like.

[0043] The power supply unit 22 is connected to the child controller 30. The power supply unit 22 supplies power to the child controller 30. The power supply unit 22 includes a battery unit 22A, an over-discharge protection circuit 22B, a power switch 22C, a battery voltage confirmation circuit 22D, and a regulator 22E.

[0044] The battery unit 22A includes a plurality of batteries (not shown) connected in series, for example. The battery unit 22A has a socket (not shown) that accommodates a plurality of batteries. The battery unit 22A supplies power to the child controller 30 via the over-discharge protection circuit 22B and the regulator 22E. The over-discharge protection circuit 22B protects the battery from over-discharge. The regulator 22E converts the output voltage from the battery unit 22A to a constant low voltage (e.g., 3.3V) required by the child controller 30. The power switch 22C is connected to the over-discharge protection circuit 22B. When the power switch 22C is ON, power is supplied from the battery unit 22A to the child controller 30. When the power switch 22C is OFF, the power supply from the battery unit 22A to the child controller 30 is cut off. The battery voltage confirmation circuit 22D is connected to the over-discharge protection circuit 22B and the child controller 30. The battery voltage confirmation circuit 22D detects the output voltage from the battery unit 22A, and outputs a detection signal to the over-discharge protection circuit 22B and the slave controller 30.

[0045] The wireless module 23 constitutes the slave side communication section. The wireless module 23 is configured similarly to the wireless module 5. The wireless module 23 of the slave 11 performs LPWA wireless communication with the wireless module 5 of the master 1. The wireless module 23 uses, for example, a LoRa communication method in the 920 MHz band. The wireless module 23 transmits or receives radio waves in the 920 MHz band from an antenna (not shown). The wireless module 23 receives a time information signal (standard radio wave data) from the master 1.

[0046] The pseudo standard radio wave output unit 24 outputs a pseudo standard radio wave based on standard radio wave data as a time information signal. The pseudo standard radio wave output unit 24 includes a standard radio wave output circuit 24A, a coil 24B, and a capacitor 24C. The standard radio wave output circuit 24A is connected to the slave controller 30. The standard radio wave output circuit 24A modulates the time code (standard radio wave data) input from the slave controller 30 onto a carrier signal of, for example, 40 kHz, and supplies the signal to the coil 24B. The coil 24B constitutes an antenna coil. The coil 24B is a small inductor with a diameter of about 5 to 10 mm (for example, 7 mm) and a length dimension in the axial direction of about 8 to 15 mm (for example, 10 mm). The coil 24B and the capacitor 24C are mounted on the control circuit board 24D and are connected in parallel with each other (see FIG. 6 and FIG. 7). At this time, the coil 24B and the capacitor 24C constitute a resonant circuit with a Q value of 40 kHz. The coil 24B emits a pseudo standard radio wave of 40 kHz (pseudo standard radio wave) based on a signal supplied from the standard radio wave output circuit 24A.

[0047] As shown in FIG. 4, the receiving antenna RA of the radio-controlled clock CLK that receives the standard radio wave tends to be located in the center of the radio-controlled clock CLK in the left-right direction. Taking this into consideration, the coil 24B is located in the center of the child unit casing 12 in the left-right direction. That is, the coil 24B is located in approximately the same position as the mounting fixture 14E of the adjuster mechanism 14 in the left-right direction of the child unit casing 12. On the other hand, the wall hanging hole of the radio-controlled clock CLK is located in the center of the left-right direction of the radio-controlled clock CLK. As a result, when the child unit 11 is attached to the back of the radio-controlled clock CLK, the coil 24B is located in a position close to the receiving antenna RA of the radio-controlled clock CLK. As a result, the receiving antenna RA of the radio-controlled clock CLK becomes more sensitive to the pseudo standard radio wave from the coil 24B. Also, the coil 24B is located in the upper part of the child unit casing 12.

[0048] The display unit 25 is attached to the front of the child device casing 12. The display unit 25 is composed of, for example, a single-color chip LED, a full-color LED, or the like. The display unit 25 is composed of, for example, two LEDs, and is connected to the child device controller 30. The display unit 25 lights up according to the current state (status) of the child device 11. Specifically, the display unit 25 switches between off, on, flashing, and lighting colors according to the sleep state, driving state, communication state with the parent device 1, error state, and the like.

[0049] Setting unit 26 is attached, for example, at a position adjacent to display unit 25. Setting unit 26 is configured, for example, by a rotary switch, and is connected to child unit controller 30. Setting unit 26 sets the number of child unit 11 by operating the rotary switch. In this way, even when multiple child units 11 communicate with a single parent unit 1, parent unit 1 can individually identify these child units 11 and transmit standard radio wave data to the child units 11.

[0050] The access switch 27 is attached, for example, to a position below the display unit 25, and is connected to the child unit controller 30. When the access switch 27 is pressed, the child unit number of the child unit 11 according to the setting unit 26 is notified to the parent unit 1, and the child unit 11 is registered in the parent unit 1.

[0051] Power switch 22C is attached, for example, to a lower position of setting unit 26 and is connected to child device controller 30. By pressing power switch 22C, child device 11 starts to operate. As a result, child device controller 30 executes a program stored in memory 30A.

[0052] The slave controller 30 is a slave control means that controls the wireless module 23 and the pseudo standard radio wave output unit 24. The slave controller 30 is configured, for example, by a microcomputer. The slave controller 30 operates according to a program stored in the memory 30A. The slave controller 30 is connected to the slave RTC 21, the wireless module 23, the pseudo standard radio wave output unit 24, the display unit 25, the setting unit 26, etc. The slave controller 30 corrects the time based on the slave RTC 21 based on the standard radio wave data from the master controller 8. This allows the slave controller 30 to obtain accurate time information using the slave RTC 21.

[0053] The slave controller 30 is connected to the pseudo standard radio wave output unit 24. The slave controller 30 outputs accurate time information acquired using the slave RTC 21 to the pseudo standard radio wave output unit 24. The pseudo standard radio wave output unit 24 generates a pseudo standard radio wave signal in which a time code (standard radio wave data) is modulated based on the acquired time information, and radiates the pseudo standard radio wave from the coil 24B.

[0054] The child unit controller 30 is normally in a sleep state. The child unit controller 30 wakes up at a predetermined wake-up date and time D11 and transmits a call signal to the parent unit controller 8. When communication is established between the child unit 11 and the parent unit 1 based on the call signal, the parent unit controller 8 transmits the standard radio wave data acquired from the standard radio wave data setting circuit 9 to the child unit 11 using the wireless module 5. When the child unit controller 30 receives the standard radio wave data using the wireless module 23, it corrects the time based on the child unit RTC 21 based on the standard radio wave data. After that, the child unit controller 30 goes into a sleep state again and waits until the predetermined start time Ts.

[0055] At the start time Ts, the slave controller 30 outputs accurate time information acquired using the slave RTC 21 to the pseudo standard radio wave output unit 24 from the start time Ts to the end time Te. This causes the slave 11 to emit a pseudo standard radio wave from the coil 24B from the start time Ts to the end time Te. The pseudo standard radio wave may be output continuously from the start time Ts to the end time Te, or may be output intermittently at regular intervals.

[0056] Since the parent unit 1 is connected to a commercial AC power source, it may be activated at all times. However, in order to reduce power consumption, it is preferable that the parent unit 1 is activated only for a necessary time from the activation date and time D10. The activation date and time D10 of the parent unit 1 is the same as the activation date and time D11 of the child unit 11. However, in order to allow for a time error due to the child unit RTC 21, the time of the activation date and time D10 is several minutes (for example, about 5 minutes) earlier than the time of the activation date and time D11. As a result, the parent unit 1 is in an activated state when the child unit 11 transmits a call signal.

[0057] The start time Ts and the end time Te are set so that the time when the radio-controlled clock CLK receives the standard radio wave and corrects the time is included between them. Generally, the radio-controlled clock CLK receives the standard radio wave between 2:00 AM and 3:30 AM and corrects the time. For this reason, the start time Ts is set to, for example, around 1:55 AM, and the end time Te is set to, for example, around 3:35 AM. In addition, the start date and time D11 of the child device 11 is set to, for example, one hour before the start time Ts.

[0058] The start dates and times D10 and D11 are set to a predetermined interval of days between 1 and 30 days, for example. Specifically, the start dates and times D10 and D11 are set to an interval of days of, for example, one week (7 days). Therefore, for example, if the start date and time D11 of the child device 11 is about 0:50 AM on January 1, the parent device 1 starts at about 0:45 AM on January 1 as the start date and time D10. Then, taking into account the time error caused by the child device RTC 21, the child device 11 calls the parent device 1 after the start date and time D11 is reached and a start reserve time (for example, one minute) has elapsed. Since the start reserve time is set, the start dates and times D10 and D11 may be the same time, for example.

[0059] The next time the parent device 1 and the child device 11 are started (next start-up date) is set to January 8, one week later. The start dates and times D10 and D11, the start time Ts, and the end time Te may be changed as appropriate according to the user's request, the specifications of the radio clock CLK, etc. In the present embodiment, the child device 11 calls the parent device 1, but the parent device 1 may be configured to call the child device 11.

[0060] Here, slave RTC 21 has a function of correcting the measured time once every 20 seconds. Slave RTC 21 is controlled by slave controller 30, measures the output frequency of crystal oscillator 21A, and sets a correction setting value based on the error between the output frequency and the reference frequency.

[0061] In the radio clock repeater, the correction setting value is calculated based on the error between the elapsed time of one week from the master unit 1 and the elapsed time of the slave unit RTC 21 of the slave unit 11. Let us assume that the elapsed time one week later is 604800 seconds, while the elapsed time of the slave unit RTC 21 is 604803 seconds, resulting in an error of 3 seconds. In this case, the correction value for the number of counts per 20 seconds can be calculated based on the following formula 1.

[0062]

number

[0063] The correction set value is set or updated based on the calculated correction value and is stored in the memory (not shown) of the slave RTC 21. If the correction value is positive, the correction value is added to the current count number per second to measure time. If the correction value is negative, the correction value is subtracted from the current count number per second to measure time. Therefore, information on whether the correction value is positive or negative is also stored in the memory of the slave RTC 21 along with the correction set value, which is an absolute value. Specifically, the absolute value and sign information of the correction value are set together in the correction register.

[0064] Next, with reference to FIG. 8, a standard radio wave data transmission process when master unit 1 transmits standard radio wave data will be described.

[0065] The parent unit 1 is normally in a sleep state. In S1, the parent unit controller 8 judges whether or not it is start-up date and time D10 based on the time information acquired using the parent unit RTC 3. If it is not start-up date and time D10, it judges "NO" in S1 and maintains the sleep state until start-up date and time D10 is reached. On the other hand, if it is start-up date and time D10, it judges "YES" in S1 and transitions to S2.

[0066] In S2, the master controller 8 judges whether or not there has been communication from the slave 11, specifically, whether or not the wireless module 5 has received a call signal from the slave 11. If the wireless module 5 has not received a call signal from the slave 11 and there has been no communication from the slave 11, the master controller 8 judges "NO" in S2 and proceeds to S3. At this time, if the master controller 8 does not receive a call signal from the slave 11 for a certain period of time (about one minute) from the start-up date and time D10 of the slave 11, for example, it judges that the communication has failed. The master controller 8 repeats this judgment at regular intervals (for example, every one to two minutes).

[0067] In S3, the master controller 8 judges whether or not communication with the slave 11 has failed a preset number of times (e.g., three times) in succession. If the number of times that communication with the slave 11 has failed in succession is less than the preset number, the master controller 8 judges "NO" in S3, returns to S2, and waits for a call signal to arrive from the slave 11.

[0068] On the other hand, if the number of consecutive failed communications with the child unit 11 reaches a predetermined number, the parent unit controller 8 judges "YES" in S3, determines that an abnormality has occurred in the communication between the parent unit 1 and the child unit 11, and proceeds to S4. In S4, the parent unit controller 8 performs communication error processing and turns on an LED or the like for displaying an error on the display unit 7 of the parent unit 1. This causes the parent unit 1 to notify that a communication error has occurred.

[0069] When the wireless module 5 receives a call signal from the child unit 11 and there is communication from the child unit 11, the parent unit controller 8 judges "YES" in S2 and proceeds to S5. In S5, since communication is established between the parent unit 1 and the child unit 11, the parent unit controller 8 transmits the standard radio wave data acquired from the standard radio wave data setting circuit 9 to the child unit 11 using the wireless module 5. Note that the transmission of the standard radio wave data is not limited to once. The parent unit 1 may transmit the standard radio wave data to the child unit 11 multiple times. When the processing of S5 ends, the processing from S1 onwards is repeated.

[0070] Next, a pseudo standard time signal transmission process when the child device 11 transmits a pseudo standard time signal will be described with reference to FIG.

[0071] The slave unit 11 is normally in a sleep state. In S11, the slave unit controller 30 judges whether or not the start-up date and time D11 has arrived based on the time information acquired using the slave unit RTC 21. If it is not the start-up date and time D11, the result in S11 is "NO" and the sleep state is maintained until the start-up date and time D11 is reached. On the other hand, if the start-up date and time D11 has arrived, the result in S11 is "YES" and the process proceeds to S12.

[0072] In S12, the slave controller 30 judges whether the spare startup time has elapsed since the startup date and time D11. If the spare startup time has not elapsed, the slave controller 30 judges "NO" in S12 and waits until the spare startup time has elapsed. On the other hand, if the spare startup time has elapsed, the wait is completed, so the slave controller 30 judges "YES" in S12 and moves to S13.

[0073] In S13, the handset controller 30 transmits a call signal to the base unit 1 through the wireless module 23. This establishes communication between the handset 11 and the base unit 1. Even if the handset 11 transmits a call signal to the base unit 1, communication may not be established when a failure occurs in either the handset 11 or the base unit 1, or when the radio wave conditions between the handset 11 and the base unit 1 deteriorate. In this case, not only the base unit 1 but also the handset 11 may be configured to perform error processing. In addition to the call signal, the handset 11 may transmit a status signal to the base unit 1 according to the status of the handset 11, such as a battery consumption status. In this case, the base unit 1 may determine whether the handset 11 is normal or abnormal based on the status signal from the handset 11, and when the handset 11 is in an abnormal state, may notify the user of the abnormality of the handset 11 using the display unit 7 or the like.

[0074] When communication is established between the slave unit 11 and the master unit 1, the process proceeds to S14, where the slave unit controller 30 determines whether or not standard radio wave data has been transmitted from the master unit 1 and time information has been acquired. If the standard radio wave data has not been received, the slave unit controller 30 determines "NO" in S14, returns to S13, and waits until the standard radio wave data is transmitted from the master unit 1. On the other hand, when the standard radio wave data is received from the master unit 1, the slave unit controller 30 determines "YES" in S14, and proceeds to S15.

[0075] S15 shows a specific example of a slave unit time correction means. In S15, slave unit controller 30 calculates accurate time information based on the standard radio wave data acquired from master unit 1. Slave unit controller 30 corrects the time information calculated using slave unit RTC 21 based on the accurate time information. Specifically, slave unit controller 30 calculates the time error caused by slave unit RTC 21 based on the accurate time information. Slave unit controller 30 then sets and updates a correction setting value, etc., for offsetting the time error. As a result, slave unit RTC 21 keeps accurate time based on the new correction setting value.

[0076] When the process of S15 is completed, the process proceeds to S16, where it is determined whether or not this is the first correction of the slave RTC 21. That is, whether or not the correction setting value is the initial value (for example, the value at the time of shipment from the factory) may be determined, or it may be determined by referring to a flag that records whether or not correction has been performed. If it is the first correction of the slave RTC 21, the result of S16 is "YES" and the process proceeds to S17. In S17, the startup standby time is shortened compared to the initial value (for example, 1 minute). Specifically, the slave controller 30 changes the startup standby time to one-third of the initial value (for example, 20 seconds). The initial value and the shortened value of the startup standby time are appropriately set in consideration of the time accuracy of the slave RTC 21, etc. When the process of S17 is completed, the process proceeds to S18.

[0077] On the other hand, if it is not the first correction of the slave RTC 21, the slave controller 30 judges "NO" in S16 and proceeds to S18. In S18, the slave controller 30 again enters the sleep state. Note that if the time interval between the end time of the processes of S15 to S17 and the start time Ts is short, the sleep process of S18 may be omitted.

[0078] In the next step S19, the slave controller 30 judges whether the start time Ts has been reached. If the start time Ts has not been reached, the slave controller 30 judges "NO" in S19 and waits until the start time Ts is reached. On the other hand, if the start time Ts has been reached, the slave controller 30 judges "YES" in S19 and proceeds to S20.

[0079] In S20, the slave controller 30 outputs accurate time information acquired using the slave RTC 21 to the pseudo standard radio wave output unit 24. The pseudo standard radio wave output unit 24 generates a pseudo standard radio wave signal in which a time code (standard radio wave data) is modulated based on the acquired time information, and causes the coil 24B to emit the pseudo standard radio wave. At this time, the pseudo standard radio wave does not need to be emitted continuously, and may be emitted at predetermined time intervals (for example, several tens of seconds to several minutes).

[0080] In the next step S21, the slave controller 30 determines whether the end time Te has been reached. If the end time Te has not been reached, the slave controller 30 determines "NO" in S21, returns to S20, and continues emitting the pseudo standard radio wave. On the other hand, if the end time Te has been reached, the slave controller 30 determines "YES" in S21, and proceeds to S22. In S22, the slave controller 30 stops emitting the pseudo standard radio wave and then transitions to a sleep state. When the process of S22 is completed, the slave controller 30 repeats S11 and subsequent steps.

[0081] Next, with reference to FIG. 10, a master RTC correction process for correcting the time kept by the master RTC 3 will be described.

[0082] When the power adapter 4A of the parent unit 1 is connected to a commercial AC power source, the parent unit controller 8 reads out the current time using the parent unit RTC 3. When this current time reaches a predetermined time (for example, 0 minutes, 15 minutes, 30 minutes, 45 minutes, etc. of every hour), the parent unit controller 8 starts the parent unit RTC correction process. At this time, in S31, the parent unit controller 8 resets the count value A0.

[0083] In S32, the current time is acquired based on the basic clock signal of the parent RTC 3, etc. Then, in S33, it is determined whether a predetermined time T0 has elapsed since the previous correction process was performed based on the current time. At this time, the predetermined time T0 is, for example, 15 minutes. If the predetermined time T0 has not elapsed, the result in S33 is "NO" and the process waits until the predetermined time T0 has elapsed. On the other hand, if the predetermined time T0 has elapsed, the result in S33 is "YES" and the process proceeds to S34.

[0084] In S34, the master controller 8 acquires a count value A0 corresponding to the predetermined time T0 based on the AC signal. Specifically, the master controller 8 measures the predetermined time T0 using the master RTC3 and at the same time counts the pulse signal of the AC signal with the pulse counter 8B. For example, when the frequency of the commercial AC power supply is 50 Hz, one second has passed when the count number of the pulse signal reaches 50. For example, when the predetermined time T0 is 15 minutes and there is no error between the time measured by the master RTC3 and the time measured by the AC signal, the count number of the pulse signal is 44999. The master controller 8 acquires the difference between the count number of the AC signal measured at the predetermined time T0 and the reference value of 44999 as the count value A0.

[0085] Therefore, the count value A0 corresponds to a first time difference, which is the difference between a first time value measured based on the periodicity of the voltage waveform from the commercial AC power supply every predetermined time T0, and a second time value measured using the parent RTC 3. In S35, the parent controller 8 stores the count value A0 acquired in S34 in the memory 8A.

[0086] To eliminate the effects of noise, pulses other than those near the AC signal period (50 Hz or 60 Hz) are removed as noise. As a specific example, if the AC signal is 50 Hz, the period until the next rising edge of the pulse signal is divided by 20 ms, and the integer part of this, 1, is added to the count value A0.

[0087] In S36, it is determined whether a predetermined data accumulation period has elapsed since the parent machine RTC correction process was started. The data accumulation period is, for example, one day (24 hours). The data accumulation period may be shorter or longer than 24 hours. However, power demand is affected by daytime power consumption. In addition, the period of the voltage waveform of the commercial AC power source varies depending on the power demand. In consideration of this, it is preferable that the predetermined period for calculating the average value is an integer multiple of one day, such as 24 hours or 48 hours.

[0088] After one data accumulation period has elapsed and the minimum count value A0 has been accumulated in the memory 8A, S36 returns "YES." In other words, S36 returns "NO" from the start of the parent RTC correction process until the first data accumulation period has elapsed.

[0089] In S37, it is determined whether the reference count value A1 has not been calculated. If the reference count value A1 has not been calculated, the result of S37 is "YES" and the process proceeds to S38. In S38, the master controller 8 calculates the average value of the count values ​​A0 during the data accumulation period (one day) based on the multiple count values ​​A0 stored in the memory 8A during the data accumulation period (one day). The master controller 8 stores this average value in the memory 8A as the reference count value A1 and proceeds to S39. On the other hand, if the reference count value A1 has already been calculated, the result of S37 is "NO" and the process proceeds to S39.

[0090] The reference count value A1 is updated, for example, every time the date changes. Therefore, when the date changes, the reference count value A1 is reset and becomes an uncalculated state. Therefore, every time the date changes, "YES" is determined in S37, and a new reference count value A1 is calculated by averaging the count value A0 of the previous day in S38.

[0091] The reference count value A1 may be updated every predetermined time T0. In this case, when the master controller 8 acquires the count value A0, it calculates the average value of the count value A0 from the time when the count value A0 was acquired until 24 hours before.

[0092] In S39, the reference count value A1 is subtracted from the current count value A0 to obtain a difference value A2 as the second time difference (A2=A0-A1). In the following S40, it is determined whether the difference value A2 exceeds a predetermined threshold value Ath. In this case, the threshold value Ath is, for example, 40 seconds. The threshold value Ath is determined, for example, by the maximum value of the RTC error and the period of the AC time fluctuation. For example, assuming that the maximum value of the RTC error is 20 ppm and the period of the AC time fluctuation is 21 days, the threshold value Ath is 36 seconds. For this reason, the threshold value Ath is set to 40 seconds as a sufficient range. Furthermore, since power companies usually correct large delays at a rate of about 1 second / hour, a difference of 40 seconds approaches 0 in about two days. For this reason, it is preferable that the threshold value Ath is set to within 60 seconds, which can be restored in 2 to 3 days. The threshold value Ath may be set based on the maximum value of the frequency fluctuation of the AC signal that occurs during the predetermined time T0. In other words, when an error occurs in the count number of the pulse signal based on the maximum value of the frequency fluctuation of the AC signal, the threshold value Ath may be set to a value that is greater than the maximum error in the count number of the pulse signal that occurs during a predetermined time T0 by a predetermined margin.

[0093] When the difference value A2 exceeds the threshold value Ath, the result of S40 is "YES" and the process proceeds to S41. In S41, a predetermined correction value C0 set in advance is added to the fixed correction value C1, and this added value is set as the correction value C. The predetermined correction value C0 is set in advance, taking into consideration the following points. The fixed correction value C1 is a fixed correction value that is set, for example, at the time of shipment from the factory, and is set in advance taking into consideration the characteristics, accuracy, etc. of the master RTC3.

[0094] Generally, the accuracy of an RTC is centered around 25°C and tends to lag at other temperatures. Taking this into consideration, the RTC correction (correction value C) for this period is set to a lead of, for example, -6 ppm. In this case, at 25°C ± 20°C, the maximum lag of 10 ppm becomes 6 ppm lead to 4 ppm lag, and the error over 21 days can be reduced from 18 seconds lag to within ±11 seconds.

[0095] If installed in a factory, for example, with an average indoor temperature of around 15°C in winter, this is equivalent to a lag of 3 ppm, and if set to a lead of -6 ppm, this is equivalent to -3 ppm, and an error of within 5.5 seconds over a 21-day period can be expected.

[0096] Also, the correction value assuming the amount of error of the RTC due to the ambient temperature may be obtained based on the temperature detected by the temperature sensor, for example. The correction value is set so as to follow the AC signal of the commercial AC power supply from the occurrence of the fluctuation until the difference value A2 exceeds the threshold value Ath (for example, 40 seconds). Therefore, when the time of the AC signal is delayed and the difference value A2 exceeds the threshold value Ath, the correction value becomes a value in the delay direction. After this, the RTC operation without feedback becomes in the advance direction, so that it moves in the direction of returning the unintended delay caused by the control. Even if there is a temporary state without feedback in this way, the error of the AC signal is continuously reduced so that the error of the AC signal is eventually reduced. At this time, even if a large fluctuation occurs, the reference count value A1 before the large fluctuation occurs is maintained. Therefore, when the power company restores the error, the RTC error does not accumulate accordingly.

[0097] The count value A0 when the determination in S40 is "YES" may be deleted from the data when calculating the reference count value A1.

[0098] On the other hand, when the difference value A2 does not exceed the predetermined threshold value Ath, the result in S40 is "NO" and the process proceeds to S42. In S42, the fluctuation correction value C2 is adjusted based on the current difference value A2 and the amount of change B from the previous difference value A2.

[0099] At this time, the fluctuation correction value C2 has a vibration suppression term C4 and a feedback term C3, as shown in the following formula 2.

[0100]

number

[0101] At this time, the master controller 8 adjusts the feedback term C3 of the fluctuation correction value C2 according to the first to third judgment situations shown below. When the previous difference value A2 is a positive value and the current difference value A2 increases in the positive direction as the first judgment situation, the master controller 8 sets the feedback term C3 to a unit correction amount (+ΔC) in the direction of advancing the time. When the previous difference value A2 is a negative value and the current difference value A2 increases in the negative direction as the second judgment situation, the master controller 8 sets the feedback term C3 to a unit correction amount (-ΔC) in the direction of delaying the time. When neither the first judgment situation nor the first judgment situation is applicable as the third judgment situation, the master controller 8 sets the feedback term C3 to 0. At this time, the unit correction amount ΔC is set based on the characteristics, accuracy, etc. of the master RTC3. Specifically, the unit correction amount ΔC is, for example, a value within a range of 1 to 4, and is preferably a value of about 2 to 3.

[0102] The oscillation frequency of the built-in crystal oscillator of the RTC (master RTC3) changes depending on the ambient temperature. Even with a highly accurate RTC, there is a fluctuation of about -5 to 20 ppm, including the initial error, at 0 to 40°C. In general RTCs, the temperature-to-error characteristics are usually designed around 25°C. In contrast, if the unit correction amount ΔC is made small, it is not possible to follow the ppm change of the RTC due to temperature changes. For example, to handle an RTC error of 10 ppm, the unit correction amount ΔC must be set to 2 or more, and to handle an RTC error of 20 ppm, the unit correction amount ΔC must be set to 3 or more. On the other hand, if the unit correction amount ΔC is made large, the fluctuation of the fluctuation correction value C2 calculated every 15 minutes will become large. The unit correction amount ΔC is set taking these characteristics into consideration.

[0103] In the above description, the unit correction amount ΔC is a constant value, but the present invention is not limited to this. For example, the unit correction amount ΔC may be set to a large value initially, such as when the power is turned on, and may be set to a small value after stabilization.

[0104] The vibration suppression term C4 suppresses the oscillation of the error value of the master RTC3 as the feedback term C3 changes. The number of data N for averaging the feedback term C3 is a value between 1 and 20, and is set to, for example, 12. If the value of the number of data N is increased, the fluctuation of the time of the master RTC3 over time becomes small, but the response time of the system that corrects the time becomes long. In this case, when the master 1 is turned on, or when the installation location of the master 1 is changed and the ambient temperature changes, it takes, for example, about 5 to 10 days for the time error of the master RTC3 to attenuate and converge. In addition, when the nature of the fluctuation of the AC signal changes, such as when the error becomes large or the period becomes long due to control by the power company, there is a possibility that it may become unstable. The number of data N is experimentally determined taking these characteristics into consideration.

[0105] The coefficient K is set to a value that does not result in over-control when the error fluctuation becomes large. Specifically, the coefficient K is set within the range of 0.5 to 0.95, for example, 0.8.

[0106] In S43, the variable correction value C2 is added to the fixed correction value C1, and this added value is set as the correction value C. After the correction value C is set in S41 and S43, S32 and subsequent steps are repeated.

[0107] The correction value C is a correction register (correction setting value) of the parent RTC 3 and must be an integer. Therefore, the correction value C is set to a value obtained by adding the fluctuation correction value C2 to the fixed correction value C1 and rounding it off. However, the correction value C may be set to a value obtained by rounding down the decimal point from the value obtained by adding the fluctuation correction value C2 to the fixed correction value C1.

[0108] In addition, the correction value C is calculated by adding the fixed correction value C1 and the variable correction value C2, but the present invention is not limited to this. For example, the correction value C may be calculated by adding a first correction value that changes in a short time and a second correction value that changes in a long time. In this case, the first correction value is set in the same manner as the variable correction value C2. On the other hand, the second correction value is a correction value that assumes an amount of error of the RTC due to, for example, the ambient temperature, and may be set according to a temperature detected by a temperature sensor (not shown).

[0109] Furthermore, the second correction value may be an average value of the correction value C over a long period such as one month, and updated daily. In this case, the correction amount including the ambient temperature and aging deterioration is set as the second correction value for the factory-set correction value C. This allows the RTC ppm error due to the RTC initial value and ambient temperature to be corrected early when the power is turned on in the same environment.

[0110] The parent unit RTC correction process has been described as being started when the parent unit 1 is powered on. However, the parent unit RTC correction process also starts when the user sets the time on the parent unit 1, just like when the power is turned on. Also, when a power outage occurs, the parent unit RTC correction process starts just like when the power is turned on.

[0111] Next, a specific example of correcting the time kept by the master RTC 3 by the master RTC correction process will be described with reference to FIGS.

[0112] First, Figure 11 shows an example of when feedback term C3 is calculated by the parent machine RTC correction process. At this time, the parent machine 1 calculates a reference count value A1 before 7:15, and this value is assumed to be -1.0. At 7:15, the parent machine 1 subtracts the reference count value A1 from the current count value A0 to calculate a difference value A2, which is the difference between the two. In addition, the amount of change B from the previous difference value A2 is calculated. Also, although the difference value A2 and the amount of change B are count values, in Figure 11 they are converted to times in seconds for ease of understanding.

[0113] As shown in FIG. 11, if the unit correction amount ΔC is "2" according to the determination algorithm, then at 7:15, 7:30, 7:45, 8:15, . . . , the feedback term C3 will be 0, 2, 0, 2, -2.

[0114] As shown in FIG. 11, for example, at 8:15, the difference value A2 is -0.8 seconds, the amount of change B is -2.0 seconds, and the measured time by the AC signal is in the negative direction, that is, in the advanced direction. At this time, the feedback term C3 indicates a delay direction of "-2". At 8:30, the difference value A2 is -1.8 seconds, and the error is increasing in the negative direction. At this time, the amount of change B is -1.0 seconds, and the feedback term C3 is in the delayed direction of "-2". At 8:45, the difference value A2 is -1.3 seconds, the amount of change B is 0.7 seconds, and the measured time by the AC signal is moving in the direction in which the error returns (decreases). At this time, the feedback term C3 becomes "0". In this way, in the parent machine RTC correction process, when the error of the AC signal becomes small, the feedback term C3 is immediately reduced to prevent unnecessary feedback from occurring.

[0115] Next, we performed a simulation of the master RTC correction process when the AC signal fluctuated. The results are shown in Figures 12 to 14.

[0116] 12 to 14 show the error in the time measured by the parent RTC3 (hereinafter referred to as the error of the parent RTC3), the error in the time measured by the AC signal (hereinafter referred to as the error of the AC signal), and the change over time in the correction value C of the parent RTC3. The horizontal axis of FIG. 12 to FIG. 14 shows the number of times in 15-minute units, and corresponds to the elapsed time from the start of the parent RTC correction process. In the upper graphs of FIG. 12 to FIG. 14, the vertical axis shows the error of the parent RTC3 and the error of the AC signal relative to the absolute time. To see the responsiveness, FIG. 12 to FIG. 14 show an example in which an error in 2-second steps occurs at the point of 1000 on the horizontal axis (the point of time when 10.4 days have elapsed).

[0117] FIG. 12 shows a case where the AC signal fluctuates by a maximum of about ±5 seconds. In FIG. 12, the initial error of the parent RTC3 is 10 ppm, and the unit correction amount ΔC is "2." After 1.7 days have passed since the initial state (at 170 on the horizontal axis), the error of the parent RTC3 is about 1 second. Furthermore, after 2.9 days have passed since 1000 on the horizontal axis, the error of the parent RTC3 is about 4 seconds. As shown in FIG. 12, the error of the AC signal is within ±3 seconds of the median value of the measurement time by the AC signal. Furthermore, the error of the AC signal changes within about 3 days, and then converges to a constant value.

[0118] Fig. 13 shows a case where the AC signal fluctuation is doubled compared to Fig. 12, to about ±10 seconds. In this case, the error of the parent RTC 3 increases compared to Fig. 12, to about 6 seconds. On the other hand, the error of the parent RTC 3 and the time fluctuation are the same as in Fig. 12.

[0119] The lower graphs in Figures 12 to 14 show the correction value C of the master RTC 3. In this case, the fixed correction value C1 is set to "0." Compared to the case of Figure 12, the amount of fluctuation in the AC signal is twice as much in the case of Figure 13, but the correction value C of the master RTC 3 is the same, and as described above, it can be seen that the master RTC correction process is effective in correcting the time of the master RTC 3.

[0120] In Figure 14, the initial error of the parent unit RTC3 is 3 ppm, and the unit correction amount ΔC is "1." In this case, the error of the parent unit RTC3 is about 3 seconds. As shown in Figure 14, if the change in the average temperature in the room where the parent unit 1 is installed is small, the unit correction amount ΔC can be made smaller, and the fluctuation of the parent unit RTC3 can be made smaller.

[0121] Thus, according to this embodiment, the master unit 1 is equipped with a master unit RTC3 that keeps time, and a master unit controller 8 (master unit control means) connected to the master unit RTC3. The master unit controller 8 calculates a count value A0 (first time difference) which is the difference between a first time value measured based on the periodicity of the voltage waveform from the commercial AC power supply at every predetermined time T0 and a second time value measured using the master unit RTC3, calculates the average value of the multiple count values ​​A0 as a reference count value A1 (reference time difference), corrects the time kept by the master unit RTC3 so that the difference value A2 which is the difference between the count value A0 and the reference count value A1 is reduced, and generates a time information signal based on the time kept by the master unit RTC3.

[0122] At this time, the count value A0 is the difference between a first time value measured based on the periodicity of the voltage waveform from the commercial AC power supply and a second time value measured using the parent RTC 3. The reference count value A1 is the average value of the multiple count values ​​A0. The difference value A2 is the difference between the count value A0 and the reference count value A1.

[0123] Therefore, by the master controller 8 correcting the time kept by the master RTC3 so that the difference value A2 decreases, the time kept by the master RTC3 tracks the reference count value A1. As a result, the influence of fluctuations in the AC signal of the commercial AC power supply can be reduced compared to when the time kept by the master RTC3 is corrected so that the count value A0 is always decreased.

[0124] As a result, parent unit 1 can obtain highly accurate time without accumulating errors by using the AC signal of commercial AC power. Also, while the time obtained by using the AC signal of commercial AC power usually fluctuates by about ±5 seconds, parent unit 1 according to this embodiment can suppress the time fluctuation to within ±3 seconds.

[0125] As a result, even if the master unit 1 is installed in an environment without windows or an environment that cannot connect to the Internet, the master unit 1 can obtain highly accurate time. In addition, the time on the master unit 1 can be made highly accurate with no accumulated error, and the error does not change continuously, causing the user to feel uncomfortable.

[0126] The radio-controlled clock repeater also includes a master unit 1 that transmits a time information signal according to standard time, and a slave unit 11 that receives the time information signal from the master unit 1 and outputs a pseudo standard radio wave. At this time, the master unit 1 corrects the error of the master unit RTC3 based on the periodicity of the voltage waveform from the commercial AC power source. This allows the master unit 1 to correct the error based on the voltage waveform of the commercial AC power source even when an error occurs in the time kept by the master unit RTC3 depending on the surrounding environment such as temperature. As a result, the master unit 1 obtains a highly accurate time using the master unit RTC3, and transmits a time information signal to the slave unit 11 based on this time. This allows the slave unit 11 to receive the time information signal from the master unit 1 and output a pseudo standard radio wave, so that the time of the radio-controlled clock CLK can be corrected by the radio-controlled clock CLK receiving the pseudo standard radio wave.

[0127] The parent unit controller 8 calculates a difference value A2 (second time difference), which is the difference between the current count value A0 (first time difference) and the reference count value A1 (reference time difference), and advances or retreats the time measured by the parent unit RTC3 by a small amount so that the difference value A2 decreases.

[0128] As a result, the time kept by the master RTC 3 is gradually adjusted so that the difference value A2 decreases. Therefore, the time kept by the master RTC 3 does not fluctuate significantly in a single correction process, and gradually changes to follow the reference count value A1.

[0129] The time kept by the master RTC3 is made faster or slower depending on the correction value C, which has a vibration suppression term C4 and a feedback term C3. In addition, when the previous difference value A2 is a positive value (A2>0) and the current difference value A2 increases in the positive direction (B>0) as the first judgment situation, the master controller 8 sets the feedback term C3 to a unit correction amount (+ΔC) in the direction of making the time faster. As a result, the correction value C changes to have an increasing tendency based on the unit correction amount ΔC, so that the time kept by the master RTC3 can be adjusted so that the difference value A2 approaches 0.

[0130] On the other hand, when the previous difference value A2 was a negative value (A2<0) and the current difference value A2 increases in the negative direction (B<0) as the second judgment situation, the master controller 8 sets the feedback term C3 to a unit correction amount (-ΔC) that delays the time. As a result, the correction value C changes to a decreasing tendency based on the unit correction amount ΔC, so that the time kept by the master RTC3 can be adjusted so that the difference value A2 approaches 0.

[0131] When the third judgment situation does not correspond to either the first judgment situation or the second judgment situation, the master controller 8 sets the feedback term C3 to 0. At this time, the correction value C does not change based on the difference value A2 or the change amount B, but is adjusted based on the vibration suppression term C4. Therefore, it is possible to suppress the vibration of the difference value A2 based on the feedback term C3.

[0132] When the difference value A2 is smaller than a predetermined threshold value Ath, the parent unit controller 8 sets a correction value C so that the difference value A2 decreases, and when the difference value A2 is larger than the threshold value Ath, the parent unit controller 8 sets the correction value C based on the temperature characteristics of the parent unit RTC3.

[0133] For example, when a normal fluctuation of about ±5 seconds occurs in the AC signal of the commercial AC power supply, the difference value A2 becomes smaller than the threshold value Ath. At this time, the master controller 8 corrects the time kept by the master RTC 3 so that the difference value A2 decreases. As a result, the time kept by the master RTC 3 gradually changes to follow the reference count value A1.

[0134] On the other hand, the period of the AC signal may change significantly due to control by the power company in rare cases. For example, the delay may be 150 seconds or more, and the delay period may exceed 10 days. At this time, the difference value A2 becomes larger than the threshold value Ath. At this time, the master controller 8 sets the correction value C based on the temperature characteristics of the master RTC3. As a result, even if the feedback control based on the AC signal is temporarily not performed, the time measured by the master RTC3 is eventually corrected so as to continuously reduce the error. As a result, even if a large fluctuation occurs, the reference count value A1 is maintained, so that when the power company restores the error, the error of the master RTC3 does not accumulate.

[0135] In this way, when a large fluctuation occurs in the AC signal, the master unit 1 of this embodiment continues to operate with the accuracy of the master unit RTC3. The time error (difference value A2) during this period is suppressed to within 20 seconds, for example, and can be reduced to within 8 seconds at around room temperature. Therefore, even if fluctuation occurs over a long period such as 21 days, a large error does not accumulate, and it is possible to keep accurate time by the subsequent correction process.

[0136] In the above embodiment, the processes of S33 and S34 in Fig. 10 show a specific example of first time difference calculation means, the process of S38 in Fig. 10 shows a specific example of reference time difference calculation means, and the processes of S39 to S43 in Fig. 10 show a specific example of correction means. The process of S39 in Fig. 10 shows a specific example of second time difference calculation means, and the processes of S40 to S43 in Fig. 10 show a specific example of time adjustment means.

[0137] In the above embodiment, the correction value C includes the fluctuation correction value C2 calculated based on the formula 2, but the present invention is not limited to this. The correction value C may be obtained by averaging a predetermined number (e.g., 20) of past difference values ​​A2 and multiplying this average value by a predetermined coefficient. In other words, the correction value C may be set to a value that offsets the average value of the past difference values ​​A2. Even in this case, the parent RTC3 can be controlled to reduce the fluctuation of the AC signal.

[0138] However, if the amount of change in the correction value C (fluctuation correction value C2) is reduced in an attempt to reduce the fluctuation, the error of the fixed offset may increase depending on the initial error of the RTC, or it may take about six days to reach a certain time. On the other hand, if the amplitude of the error in the AC signal is doubled, the fluctuation of the RTC increases, and the fluctuation of the correction value C also increases significantly.

[0139] The pseudo standard radio wave output unit 24 is not limited to outputting a pseudo standard radio wave of 40 kHz, but may output a pseudo standard radio wave of 60 kHz. In this case, the coil 24B and the capacitor 24C form a resonant circuit with a Q value of 60 kHz. The frequency of the pseudo standard radio wave may be selected to output either 40 kHz or 60 kHz.

[0140] The slave controller 30 causes the pseudo standard radio wave output unit 24 to output a pseudo standard radio wave at 40 kHz. This allows the pseudo standard radio wave output unit 24 to output a pseudo standard radio wave at 40 kHz every predetermined period. The slave controller 30 may also be configured to output a pseudo standard radio wave at 60 kHz from the pseudo standard radio wave output unit 24.

[0141] The slave unit 11 need not necessarily be placed on the rear side of the radio-controlled clock CLK, but may be placed anywhere near the radio-controlled clock CLK within the range where the pseudo standard radio waves can reach.

[0142] In the above embodiment, the pseudo standard radio wave transmission process of slave unit 11 is to correct the time of slave unit RTC 21 and output the pseudo standard radio wave after acquiring the time information signal (standard radio wave data) from master unit 1. The present invention is not limited to this, and in the pseudo standard radio wave transmission process of slave unit 11, even if the time information signal (standard radio wave data) cannot be acquired from master unit 1, slave unit 11 may output the pseudo standard radio wave as long as the time of slave unit RTC 21 has been corrected.

[0143] In the above embodiment, the slave 11 performs time correction of the slave RTC 21 and output of the pseudo standard radio wave on the same day. However, the present invention is not limited to this, and the slave RTC 21 may perform time correction and output of the pseudo standard radio wave on different days. [Explanation of symbols]

[0144] 1 Parent unit 3 Parent unit real-time clock (parent unit RTC) 5 Wireless module (parent device communication section) 8. Parent controller (parent control means) 11 Child unit 21 Child unit real-time clock (child unit RTC) 23 Wireless module (child device communication section) 24 Pseudo standard radio wave output section 30 Child unit controller (child unit control means)

Claims

1. A radio-controlled clock repeater including a master unit that transmits a time information signal according to a standard time, and a slave unit that receives the time information signal from the master unit and outputs a pseudo standard radio wave, The parent unit is A parent real-time clock that keeps track of time; a master control means connected to the master real-time clock; The parent device control means a first time difference calculation means for calculating a first time difference which is a difference between a first time value measured based on the periodicity of a voltage waveform from a commercial AC power supply at every predetermined time and a second time value measured using the parent device real-time clock; a reference time difference calculation means for calculating an average value of a plurality of the first time differences as a reference time difference; a correction means for correcting the time kept by the master real-time clock so that the difference between the first time difference and the reference time difference decreases; a time information signal generating means for generating the time information signal based on the time kept by the master real-time clock.

2. The correction means is a second time difference calculation means for calculating a second time difference which is a difference between the first time difference calculated by the first time difference calculation means and the reference time difference; 2. A radio-controlled clock repeater as claimed in claim 1, further comprising a time adjustment means for advancing or retarding the time kept by the master real-time clock by a small amount so as to reduce the second time difference.

3. The time kept by the parent device real-time clock is made faster or slower depending on the correction value, the correction value includes a vibration suppression term and a feedback term, The time adjustment means is When the second time difference of the previous time is a positive value and the second time difference of the current time increases in a positive direction as a first determination state, the feedback term is set to a unit correction amount in a direction to advance the time; as a second determination state, when the previous second time difference was a negative value and the current second time difference has increased in a negative direction, the feedback term is set to a unit correction amount in a direction that delays the time; 3. The radio-controlled clock repeater according to claim 2, wherein when a third judgment situation corresponds to neither the first judgment situation nor the second judgment situation, the feedback term is set to 0.

4. The time adjustment means is When the second time difference is smaller than a predetermined threshold value, the correction value is set so that the second time difference is reduced; 4. The radio-controlled clock repeater according to claim 3, wherein when the second time difference is greater than the threshold value, the correction value is set based on the temperature characteristics of the master real-time clock.

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