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) with the same specifications as a standard radio wave toward a radio-controlled clock. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-183501 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-88202 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-327871 Summary of the Invention [Problem to be solved by the invention]

[0004] 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 cannot receive standard radio waves propagating outdoors, such as indoors isolated from the outside.

[0005] Meanwhile, various electronic devices obtain the current time using a real-time clock (RTC). A known method for 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 current time correction method is applied to a radio-controlled clock repeater, the radio-controlled clock repeater can generate a pseudo standard time signal based on the accurate time, even in an environment where it cannot receive standard time signals.

[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, resulting from changes in the generator's rotation speed and power companies adjusting the amount of power generated. For this reason, the fluctuation is unpredictable and resembles noise. Therefore, when time information is obtained using the voltage waveform of a commercial AC power supply, it keeps accurate time over the long term and the cumulative error does not increase, but there is a problem in that momentary errors of up to ±5 seconds can occur.

[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 real-time clock that keeps time, and a parent control means connected to the parent real-time clock, and the parent 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 predetermined intervals and a second time value measured using the parent 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 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 real-time clock. [Effects of the Invention]

[0009] According to the present invention, the master control means corrects the time kept by the master 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 master real-time clock tracks the reference time difference. As a result, the influence of fluctuations in the voltage waveform of the commercial AC power supply is reduced, and errors when time information is obtained based on the voltage waveform of the commercial AC power supply can be suppressed. [Brief explanation 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; [Figure 2] FIG. 2 is a front view showing the base unit in FIG. [Figure 3] FIG. 2 is a block diagram showing the configuration of a parent device. [Figure 4] FIG. 2 is a front view showing the slave unit in FIG. [Figure 5] FIG. 2 is a perspective view showing a state in which the handset is attached to a wall. [Figure 6] FIG. [Figure 7] FIG. 2 is a block diagram showing the configuration of a slave unit. [Figure 8] 10 is a flowchart showing standard radio wave data transmission processing by the master unit. [Figure 9] 10 is a flowchart showing a pseudo standard time radio wave transmission process by a slave unit. [Figure 10] 10 is a flowchart showing a parent device RTC correction process. [Figure 11] FIG. 2 is a characteristic diagram showing an example of time variations in the error and feedback term of an AC signal. [Figure 12] FIG. 10 is a characteristic diagram showing an example of changes over time in the error of the master RTC, the error of the AC signal, and the correction value of the master RTC when the AC signal fluctuates by a maximum of approximately ±5 seconds. [Figure 13] FIG. 10 is a characteristic diagram showing an example of changes over time in the error of the master RTC, the error of the AC signal, and the correction value of the master RTC when the AC signal fluctuates by a maximum of approximately ±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 when the unit correction amount is set to half that of FIG. DETAILED DESCRIPTION OF THE INVENTION

[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 flowcharts shown in Figures 8, 9, and 10 will be designated by the letter "S" (for example, step 1 will be designated 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] As shown in Figures 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, wireless module 5, and 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 quartz 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 4 via the master controller 8. Therefore, when the main power supply 4 is connected to a commercial AC power source, the master RTC 3 is driven by the power supplied from the main power supply 4. The master RTC 3 determines 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 corresponding to the oscillation frequency, the master RTC 3 counts the basic clock signal and measures time based on the count. For example, if the reference oscillation frequency of the crystal oscillator 3A is 32,768 Hz, the master RTC 3 will mark one second when the count reaches 32,769.

[0016] The master RTC 3 also has a function (correction function) for adjusting the count, for example, every 20 seconds, to correct the measured time. Specifically, the master RTC 3 corrects the measured time by increasing or decreasing the count per unit time (e.g., 1 second) of the basic clock signal. For example, if the reference oscillation frequency of the crystal oscillator 3A is 32,768 Hz and the actual oscillation frequency is higher than the reference oscillation frequency, 32,768.1 Hz (= +3.05 ppm), the master RTC 3 increases the count value once every 20 seconds and counts 32,770 times to mark one second. If the actual oscillation frequency of the crystal oscillator 3A is lower than the reference oscillation frequency, the master RTC 3 decreases the count value once every 20 seconds according to the frequency error to mark one second. Note that the time interval for correcting the master RTC 3's time 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 stores the count number correction setting value (adjustment amount) and increase / decrease information in memory (not shown). Therefore, the master RTC 3 corrects the measured time by updating the count number correction setting value and increase / decrease information according to the time error.

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

[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, with 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 with various converter circuits and converts the AC power to 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 (e.g., 3.3 V) required by the parent controller 8. The low-voltage power supply circuit 4C is configured, for example, with 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 supply output from the power adapter 4A and outputs an AC signal corresponding to this AC voltage to the parent unit controller 8. At this time, the AC signal extraction circuit 4D forms a pulse conversion unit and converts the sinusoidal AC signal into a pulse signal. The parent unit controller 8 includes a pulse counter 8B that counts the pulse signals. The main power supply unit 4, except for the power adapter 4A, is housed in the parent unit casing 2. 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 unit casing 2.

[0021] The wireless module 5 constitutes the parent device side communication unit. The wireless module 5 of the parent device 1 performs LPWA (Low Power Wide Area Network) wireless communication with the wireless module 23 of the child device 11. The wireless module 5 uses, for example, the LoRa communication method in the 920 MHz band. This makes the wireless module 5 relatively resistant to external disturbances and capable of long-distance communication. The wireless module 5 transmits and 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, 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 configured with, for example, a 7-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, etc. The display unit 7 lights up as an error indicator 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 the voltage signal (AC signal) of the 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, when the voltage signal of commercial AC power is used as the clock's oscillator circuit, there is no constant "error per month" as with a quartz crystal oscillator, and the cumulative error can be maintained within a 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 master controller 8 is powered by commercial AC power, it executes the master RTC correction process described below.

[0026] In the master RTC correction process, master controller 8 corrects the time kept by master RTC 3 at intervals of a predetermined time T0, such as once every 15 minutes. At this time, 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 master RTC 3 (second time value) every predetermined time T0. Based on this time difference (time difference), master controller 8 changes the correction setting value of master RTC 3. This allows master controller 8 to obtain accurate time information using master RTC 3.

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

[0030] As shown in Figures 4 to 6, handset 11 includes handset casing 12, latch 13, and adjuster mechanism 14. Handset casing 12 is formed in a flat plate shape with a predetermined thickness and is composed of main unit housing section 12A and lid section 12B. Main unit housing section 12A is formed in the shape of, for example, a rectangular box, and is open on the front side. Inside main unit 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 portion 12A by screws or the like. The lid 12B is located on the front side of the main body housing portion 12A and covers the opening of the main body housing portion 12A. A window 12C is formed in the center of the lid 12B. The window 12C is formed, for example, by a rectangular through-hole, and inside the window 12C, the power switch 22C, the display portion 25, the setting portion 26, the 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 top of the handset casing 12. A wall-hanging hole 13A, e.g., a pentagonal through-hole, is formed in the center of the hanging device 13. The tip of a hook-shaped mounting fixture F attached to, e.g., a wall W of a building, is inserted into the uppermost corner 13B of the wall-hanging hole 13A. This allows the hanging device 13 to secure the handset 11 to the wall in a hanging state. A latch member 13C is attached to the hanging device 13. The latch member 13C is attached to holding portions 13D, 13E provided on both lateral ends of the hanging device 13. The latch member 13C is located below the corner 13B of the wall-hanging hole 13A and extends in the lateral direction of the hanging device 13, straddling the wall-hanging hole 13A. The mounting fixture F fixed to the wall surface W is inserted into the wall-hanging hole 13A with the latch member 13C removed, and is fixed at the position of the corner 13B. As a result, the latch member 13C allows the mounting fixture F fixed to the wall (wall surface W) to be inserted into the corner 13B of the wall-hanging hole 13A. The latch member 13C is attached to the latch 13 after the mounting fixture F is inserted into the wall-hanging hole 13A. As a result, the latch member 13C 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 latching device 13 and extends vertically. A guide hole 14B consisting of a long, narrow slit extending vertically is formed in the center of the rail member 14A. The rail member 14A is attached to the front side of the latching device 13 via, for example, three spacers 14C. One spacer 14C is disposed at the upper end of the rail member 14A, and two spacers 14C are disposed at the lower end of the rail member 14A. The spacers 14C are disposed between the rail member 14A and the latching device 13, so that the rail member 14A faces the latching device 13 with a gap between them. A latch member 13C is inserted between the rail member 14A and the latching device 13.

[0034] The slider 14D is made up 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) for the radio-controlled clock CLK and supports 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 made of, for example, a metal material. The outer peripheral surface of the disk portion is knurled. The disk portion of the mounting fixture 14E acts as a stopper to prevent the radio-controlled clock CLK from falling out of 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 toward 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, restricting vertical displacement of the slider 14D and fixing it 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 directions that separate them from each other, thereby releasing the state in which the two plate-like members hold the rail member 14A between them, and allowing the slider 14D to move up and down.

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

[0039] The slave RTC 21 is configured in a similar manner to the master RTC 3. Therefore, the slave RTC 21 is configured using, for example, a quartz oscillator 21A to measure the 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. Therefore, the slave RTC 21 is driven by the power supplied from the power supply unit 22. The slave RTC 21 determines the current time based on the initial time input by a time setting unit (not shown) of the slave RTC 21. The initial time of the slave RTC 21 does not necessarily have to be set by the slave 11, but may be set by the master 1 using communication between the master RTC 1 and the slave 11. The slave RTC 21 outputs a signal corresponding to the current time to the slave controller 30. Like the master RTC 3, the slave RTC 21 also has a built-in correction function for correcting errors.

[0040] At this time, when crystal oscillator 21A outputs a basic clock signal corresponding to the oscillation frequency, slave RTC 21 counts the basic clock signal and measures time based on the count. For example, if the reference oscillation frequency of crystal oscillator 21A is 32,768 Hz, slave RTC 21 marks one second when the count reaches 32,769.

[0041] The slave RTC 21 also has a function for adjusting the count, for example, every 20 seconds, to correct the measured time. Specifically, the slave RTC 21 corrects the measured time by increasing or decreasing the count per unit time (e.g., 1 second) of the master clock signal. For example, if the reference oscillation frequency of crystal oscillator 21A is 32,768 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 in accordance with the frequency error to mark each second. If the actual oscillation frequency of crystal oscillator 21A is lower than the reference oscillation frequency, the slave RTC 21 decreases the count value once every 20 seconds in accordance with the frequency error to mark each 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.

[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 measured time by updating the correction set value of the count number and information on the increase / decrease in accordance with the time error. Information such as the correction set value is set at the time of factory manufacture 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, such as a button battery or capacitor.

[0043] The power supply unit 22 is connected to the slave controller 30. The power supply unit 22 supplies power to the slave 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, for example, a plurality of batteries (not shown) connected in series. The battery unit 22A has a socket (not shown) that accommodates the plurality of batteries. The battery unit 22A supplies power to the slave controller 30 via an over-discharge protection circuit 22B and a regulator 22E. The over-discharge protection circuit 22B protects the batteries from over-discharge. The regulator 22E converts the output voltage from the battery unit 22A to a constant low voltage (e.g., 3.3 V) required by the slave 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 slave controller 30. When the power switch 22C is OFF, power supply from the battery unit 22A to the slave controller 30 is cut off. The battery voltage confirmation circuit 22D is connected to the over-discharge protection circuit 22B and the slave 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 device side communication unit. The wireless module 23 is configured in the same manner as the wireless module 5. The wireless module 23 of the slave device 11 performs LPWA wireless communication with the wireless module 5 of the master device 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 device 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, for example, a 40 kHz carrier signal and supplies the modulated signal to the coil 24B. The coil 24B forms an antenna coil. The coil 24B is a small inductor with a diameter of approximately 5 to 10 mm (e.g., 7 mm) and an axial length of approximately 8 to 15 mm (e.g., 10 mm). The coil 24B and the capacitor 24C are mounted on a control circuit board 24D and connected in parallel with each other (see FIGS. 6 and 7). In this case, the coil 24B and the capacitor 24C form 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 the 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, which receives the standard time signal, tends to be located in the center of the radio-controlled clock CLK in the horizontal direction. Taking this into consideration, the coil 24B is located in the center of the slave unit casing 12 in the horizontal direction. That is, the coil 24B is located in approximately the same position as the mounting bracket 14E of the adjuster mechanism 14 in the horizontal direction of the slave unit casing 12. Meanwhile, the wall-hanging hole of the radio-controlled clock CLK is located in the center of the radio-controlled clock CLK in the horizontal direction. As a result, when the slave unit 11 is attached to the back of the radio-controlled clock CLK, the coil 24B is located 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 is highly sensitive to the pseudo standard time signal from the coil 24B. Furthermore, the coil 24B is located in the upper portion of the slave unit casing 12.

[0048] The display unit 25 is attached to the front of the slave unit casing 12. The display unit 25 is configured, for example, by a single-color chip LED, a full-color LED, or the like. The display unit 25 is configured, for example, by two LEDs, and is connected to the slave unit controller 30. The display unit 25 lights up according to the current state (status) of the slave unit 11. Specifically, the display unit 25 switches between off, on, blinking, and lighting color according to the sleep state, driving state, communication state with the master unit 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, with a rotary switch, and is connected to slave unit controller 30. Setting unit 26 sets the number of slave unit 11 by operating the rotary switch. This allows master unit 1 to individually identify each of these slave units 11 and transmit standard radio wave data to each of them, even when multiple slave units 11 communicate with a single master unit 1.

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

[0051] Power switch 22C is attached, for example, to a position below setting unit 26 and is connected to slave unit controller 30. Pressing power switch 22C starts slave unit 11. This causes slave unit controller 30 to execute a program stored in memory 30A.

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

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

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

[0056] Since the base unit 1 is connected to a commercial AC power source, it may be kept running at all times. However, to reduce power consumption, it is preferable that the base unit 1 be operated only for the required time from the start-up date and time D10. The start-up date and time D10 of the base unit 1 is the same as the start-up date and time D11 of the slave unit 11. However, to allow for a time error due to the slave unit RTC 21, the start-up date and time D10 is set several minutes (for example, about 5 minutes) earlier than the start-up date and time D11. As a result, the base unit 1 is in an operating state when the slave unit 11 transmits a call signal.

[0057] The start time Ts and end time Te are set so that they include the time when the radio-controlled clock CLK receives the standard radio wave and adjusts the time. Generally, the radio-controlled clock CLK receives the standard radio wave and adjusts the time between 2:00 AM and 3:30 AM. 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 slave device 11 is set to, for example, one hour before the start time Ts.

[0058] The activation dates and times D10 and D11 are set at intervals of a predetermined number of days between, for example, 1 and 30 days. Specifically, the activation dates and times D10 and D11 are set at intervals of, for example, one week (7 days). Therefore, for example, if the activation date and time D11 of the slave device 11 is set to start at approximately 12:50 AM on January 1st, the master device 1 will start at approximately 12:45 AM on January 1st as the activation date and time D10. Then, taking into account the time error caused by the slave device RTC 21, the slave device 11 calls the master device 1 after a startup reserve time (for example, one minute) has elapsed since the activation date and time D11 was reached. Because the startup reserve time is set, the activation dates and times D10 and D11 may be the same time, for example.

[0059] The next time the master unit 1 and slave unit 11 are started (next start-up date) is set to January 8th, 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 addition, although the slave unit 11 calls the master unit 1 in this embodiment, the master unit 1 may also be configured to call the slave unit 11.

[0060] Here, slave RTC 21 has the function of correcting the measurement 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] The radio-controlled clock repeater calculates a correction setting value 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's assume that the elapsed time of one week is 604,800 seconds, while the elapsed time of the slave unit RTC 21 is 604,803 seconds, resulting in an error of three seconds. In this case, the correction value for the number of counts per 20 seconds can be calculated using the following formula 1.

[0062]

number

[0063] The correction setting 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 number of counts per second to measure time. If the correction value is negative, the correction value is subtracted from the current number of counts 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 setting 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 determines whether or not the start-up date and time D10 has arrived based on the time information acquired using the parent unit RTC 3. If it is not the start-up date and time D10, the result in S1 is "NO" and the parent unit 1 remains in the sleep state until the start-up date and time D10 arrives. On the other hand, if the start-up date and time D10 has arrived, the result in S1 is "YES" and the process proceeds to S2.

[0066] In S2, the master controller 8 determines 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 determines "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 determines that the communication has failed. The master controller 8 repeats this determination at regular intervals (for example, every one to two minutes).

[0067] In S3, the base unit controller 8 determines whether communication with the handset 11 has failed a predetermined number of times (for example, three times) in succession. If the number of times that communication with the handset 11 has failed in succession is less than the predetermined number, the base unit controller 8 determines "NO" in S3, returns to S2, and waits for a call signal to arrive from the handset 11.

[0068] On the other hand, if the number of consecutive communication failures with the slave unit 11 reaches a predetermined number, the master unit controller 8 determines "YES" in S3, determines that an abnormality has occurred in the communication between the master unit 1 and the slave unit 11, and proceeds to S4. In S4, the master 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 master unit 1. This causes the master unit 1 to notify that a communication error has occurred.

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

[0070] Next, with reference to FIG. 9, a pseudo standard time signal transmission process when the slave unit 11 transmits a pseudo standard time signal will be described.

[0071] The slave unit 11 is normally in a sleep state. In S11, the slave unit controller 30 determines whether 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 slave unit controller 30 determines "NO" in S11 and maintains the sleep state until the start-up date and time D11 arrives. On the other hand, if the start-up date and time D11 has arrived, the slave unit controller 30 determines "YES" in S11 and proceeds to S12.

[0072] In S12, the slave controller 30 determines 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 determines "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 complete, so the slave controller 30 determines "YES" in S12 and proceeds 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. Note that even if the handset 11 transmits a call signal to the base unit 1, communication may not be established if a malfunction occurs in either the handset 11 or the base unit 1, or if 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. Furthermore, 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 the 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 if 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 the master unit 1 has transmitted standard radio wave data and acquired time information. If the slave unit controller 30 has not received standard radio wave data, 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, if the slave unit controller 30 has received standard radio wave data 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 correction settings and the like to offset the time error. As a result, slave unit RTC 21 will keep accurate time based on the new correction settings.

[0076] When the process of S15 is completed, the process proceeds to S16, where it is determined whether this is the first time the slave device RTC 21 is corrected. That is, whether this is the first time the slave device RTC 21 is corrected may be determined by whether the correction setting value is an initial value (e.g., a value at the time of shipment from the factory) or by referring to a flag that records whether correction has been performed. If this is the first time the slave device RTC 21 is corrected, the process returns "YES" in S16 and proceeds to S17. In S17, the startup standby time is shortened from its initial value (e.g., 1 minute). Specifically, the slave device controller 30 changes the startup standby time to one-third of the initial value (e.g., 20 seconds). The initial value and the shortened value of the startup standby time are set appropriately taking into consideration the time accuracy of the slave device RTC 21, etc. When the process of S17 is completed, the process proceeds to S18.

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

[0078] In the next step S19, the slave controller 30 determines whether the start time Ts has been reached. If the start time Ts has not been reached, the slave controller 30 determines "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 determines "YES" in S19 and proceeds to S20.

[0079] In S20, slave controller 30 outputs accurate time information acquired using slave RTC 21 to pseudo standard radio wave output unit 24. Pseudo standard radio wave output unit 24 generates a pseudo standard radio wave signal in which the time code (standard radio wave data) is modulated based on the acquired time information, and causes 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, from several tens of seconds to several minutes).

[0080] In the following 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 time 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 time radio wave and then enters a sleep state. When the processing 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 power adapter 4A of master unit 1 is connected to a commercial AC power source, master unit controller 8 reads the current time using master unit RTC 3. When this current time reaches a predetermined time (for example, 0, 15, 30, 45 minutes past the hour), master unit controller 8 starts master unit RTC correction processing. At this time, in S31, master unit controller 8 resets count value A0.

[0083] In S32, the current time is acquired based on the basic clock signal of the parent device RTC3, etc. Next, in S33, it is determined based on the current time whether a predetermined time T0 has elapsed since the previous correction process was performed. In this case, the predetermined time T0 is, for example, 15 minutes. If the predetermined time T0 has not elapsed, the determination in S33 is "NO" and the process remains on standby until the predetermined time T0 has elapsed. On the other hand, if the predetermined time T0 has elapsed, the determination 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 RTC 3 while simultaneously counting the pulse signal of the AC signal using pulse counter 8B. For example, if the commercial AC power frequency is 50 Hz, one second has passed when the pulse signal count reaches 50. For example, if the predetermined time T0 is 15 minutes and there is no error between the time measured by the master RTC 3 and the time measured by the AC signal, the pulse signal count will be 44,999. The master controller 8 acquires the difference between the count of the AC signal measured during the predetermined time T0 and the reference value of 44,999 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 memory 8A.

[0086] To eliminate the effects of noise, pulses outside the vicinity of 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 start of the parent device RTC correction process. 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. Furthermore, the period of the voltage waveform of the commercial AC power supply varies depending on power demand. Taking this into consideration, it is preferable that the predetermined period for calculating the average value be an integral 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 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 determination in 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 memory 8A during the data accumulation period (one day). The master controller 8 stores this average value in 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 determination in 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 uncalculated. Therefore, every time the date changes, the determination in S37 is "YES," and a new reference count value A1 is calculated by averaging the count values ​​A0 for 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 up to 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, based on the maximum RTC error and the period of AC time fluctuation. For example, if the maximum RTC error is 20 ppm and the period of 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, which is a sufficient range. Furthermore, since power companies typically correct large delays by approximately 1 second per hour, a 40-second difference approaches zero in about two days. For this reason, it is preferable to set the threshold value Ath within 60 seconds, which allows recovery within two to three days. The threshold value Ath may also be set based on the maximum frequency fluctuation of the AC signal occurring during a predetermined time period 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 larger by a predetermined margin than the maximum error in the count number of the pulse signal that occurs during a predetermined time T0.

[0093] If the difference value A2 exceeds the threshold value Ath, the determination in 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 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, RTC accuracy tends to lag at temperatures other than 25°C. 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 lead of 10 ppm becomes 6 ppm lead to 4 ppm lead, reducing the error over 21 days from 18 seconds lead to within ±11 seconds.

[0095] If installed in a factory, etc., with an average indoor temperature of around 15°C in winter, this is equivalent to a delay 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 21 days can be expected.

[0096] Furthermore, a correction value that takes into account the RTC error due to ambient temperature may be calculated based on the temperature detected by a temperature sensor, for example. The correction value is set to track the AC signal from the commercial AC power supply from the time the fluctuation occurs until the difference value A2 exceeds the threshold Ath (e.g., 40 seconds). Therefore, if the AC signal time lags and the difference value A2 exceeds the threshold Ath, the correction value becomes a value in the delay direction. After this, the RTC operates in the advance direction without feedback, so it moves in the direction of correcting the unintended delay caused by control. Even in this temporary state without feedback, the AC signal error is continuously reduced so that the error ultimately becomes smaller. Even if a large fluctuation occurs, the reference count value A1 before the large fluctuation occurs is maintained. Therefore, if the power company corrects the error, the RTC error will not accumulate.

[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, if the difference value A2 does not exceed the predetermined threshold value Ath, the determination 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 equation 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, as a first judgment situation, the previous difference value A2 was a positive value and the current difference value A2 has increased in a positive direction, the master controller 8 sets the feedback term C3 to a unit correction amount (+ΔC) in a direction to advance the time. When, as a second judgment situation, the previous difference value A2 was a negative value and the current difference value A2 has increased in a negative direction, the master controller 8 sets the feedback term C3 to a unit correction amount (-ΔC) in a direction to delay the time. When, as a third judgment situation, neither the first judgment situation nor the first judgment situation applies, 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 a value within a range of 1 to 4, for example, and preferably a value of about 2 to 3.

[0102] The oscillation frequency of the built-in crystal oscillator in the RTC (master RTC3) changes depending on the ambient temperature. Even highly accurate RTCs have a variation of approximately -5 to 20 ppm, including the initial error, between 0 and 40°C. Typical RTCs are typically designed with a temperature-to-error ratio of 25°C. In contrast, a small unit correction value ΔC cannot track the ppm changes in the RTC due to temperature fluctuations. For example, to accommodate an RTC error of 10 ppm, the unit correction value ΔC must be set to 2 or more, and to accommodate an RTC error of 20 ppm, the unit correction value ΔC must be set to 3 or more. On the other hand, increasing the unit correction value ΔC increases the fluctuation of the fluctuation correction value C2, which is calculated every 15 minutes. The unit correction value ΔC is set with these characteristics in mind.

[0103] Although the unit correction amount ΔC is a constant value in the above example, 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 then set to a small value after stabilization.

[0104] The vibration suppression term C4 suppresses the oscillation of the error value of the master RTC 3 due to changes in the feedback term C3. The number of data N used to average the feedback term C3 is a value between 1 and 20, and is set to 12, for example. Increasing the number of data N reduces the time fluctuations of the master RTC 3 over time, but increases the response time of the time correction system. In this case, when the master RTC 1 is powered on or when the installation location of the master RTC 1 changes and the ambient temperature changes, it may take approximately 5 to 10 days for the time error of the master RTC 3 to decay and converge. Furthermore, changes in the nature of the AC signal fluctuations, such as larger errors or longer periods due to control by the power company, can cause instability. The number of data N is determined experimentally, taking these characteristics into consideration.

[0105] The coefficient K is set to a value that will not result in over-control when the error fluctuations become 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 sum 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 variable correction value C2 to the fixed correction value C1 and rounding it off. However, the correction value C may also be set to a value obtained by rounding down the decimal point from the value obtained by adding the variable correction value C2 to the fixed correction value C1.

[0108] Furthermore, although the correction value C is calculated by adding the fixed correction value C1 and the variable correction value C2, 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 over a short period of time and a second correction value that changes over a long period of time. In this case, the first correction value is set in the same manner as the variable correction value C2. Meanwhile, the second correction value is a correction value that assumes the amount of RTC error due to, for example, ambient temperature, and may be set according to the temperature detected by a temperature sensor (not shown).

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

[0110] The parent unit RTC correction process has been described as starting when the parent unit 1 is powered on. However, this is not the only case. 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. The parent unit RTC correction process also starts when a power outage occurs, just like when the power is turned on.

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

[0112] First, Figure 11 shows an example of when the feedback term C3 is calculated using the parent machine RTC correction process. At this time, 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 reference count value A1 is subtracted 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. Although difference value A2 and amount of change B are count values, they are converted to time in seconds in Figure 11 for ease of understanding.

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

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

[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 master RTC 3 (hereinafter referred to as the master RTC 3 error), the error in the time measured by the AC signal (hereinafter referred to as the AC signal error), and the change over time in the master RTC 3 correction value C. The horizontal axis in FIGS. 12 to 14 represents the number of 15-minute intervals, corresponding to the elapsed time since the master RTC correction process began. In the upper graphs of FIGS. 12 to 14, the vertical axis represents the master RTC 3 error and AC signal error relative to absolute time. To examine responsiveness, FIGS. 12 to 14 illustrate an example in which an error in 2-second steps occurs at the horizontal axis of 1000 (corresponding to the time when 10.4 days have elapsed).

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

[0118] FIG. 13 shows a case where the AC signal fluctuation is doubled compared to the case in FIG. 12, to approximately ±10 seconds. In this case, the error of the master RTC 3 increases compared to the case in FIG. 12, to approximately 6 seconds. However, the error and time fluctuation of the master RTC 3 remain the same as in the case 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 Figure 12, the amount of fluctuation in the AC signal in Figure 13 is twice as much, but the correction value C of the master RTC 3 is the same, and as mentioned 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 master RTC3 is 3 ppm, and the unit correction amount ΔC is "1." In this case, the error of the master RTC3 is about 3 seconds. As shown in Figure 14, if the change in the average temperature in the room where the master RTC 1 is installed is small, the unit correction amount ΔC can be made smaller, and the fluctuation of the master RTC3 can be reduced.

[0121] Thus, according to this embodiment, the master unit 1 comprises 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] In this case, 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. Furthermore, reference count value A1 is the average value of multiple count values ​​A0. Furthermore, difference value A2 is the difference between count value A0 and reference count value A1.

[0123] Therefore, by having master controller 8 correct the time kept by master RTC 3 so that difference value A2 decreases, the time kept by master RTC 3 follows 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 master RTC 3 is corrected so that count value A0 is always decreased.

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

[0125] This allows the base unit 1 to obtain highly accurate time even if it is installed in an environment without windows or without internet access. In addition, the time on the base unit 1 can be highly accurate with no cumulative 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. The master unit 1 corrects the error of the master unit RTC 3 based on the periodicity of the voltage waveform from the commercial AC power supply. This allows the master unit 1 to correct the time error based on the voltage waveform of the commercial AC power supply, even if the time kept by the master unit RTC 3 varies depending on the ambient temperature and other factors. As a result, the master unit 1 obtains highly accurate time using the master unit RTC 3 and transmits a time information signal to the slave unit 11 based on this time. The slave unit 11 receives the time information signal from the master unit 1 and outputs a pseudo standard radio wave. The radio-controlled clock CLK can then correct the time by receiving the pseudo standard radio wave.

[0127] The parent 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 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 RTC 3 is advanced or delayed according to the correction value C, which has a vibration suppression term C4 and a feedback term C3. In addition, when the previous difference value A2 was a positive value (A2>0) and the current difference value A2 has increased in the positive direction (B>0), as a first determination situation, the master controller 8 sets the feedback term C3 to a unit correction amount (+ΔC) that advances the time. As a result, the correction value C tends to increase based on the unit correction amount ΔC, and the time kept by the master RTC 3 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 a 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, and the time kept by the master RTC 3 can be adjusted so that the difference value A2 approaches 0.

[0131] When the third determination situation corresponds to neither the first nor the second determination 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 amount of change 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 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 controller 8 sets the correction value C based on the temperature characteristics of the parent RTC 3.

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

[0134] However, in rare cases, the AC signal period may change significantly due to control by the power company. For example, the delay may be 150 seconds or more, or even longer than 10 days. In this case, the difference value A2 exceeds the threshold value Ath. At this time, the master controller 8 sets the correction value C based on the temperature characteristics of the master RTC 3. As a result, even if feedback control based on the AC signal is temporarily disabled, the time measured by the master RTC 3 is ultimately corrected to continuously reduce the error. As a result, even if a large fluctuation occurs, the reference count value A1 is maintained. Therefore, when the power company corrects the error, the error in the master RTC 3 does not accumulate.

[0135] In this way, even if 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 RTC 3. The time error (difference value A2) during this period is suppressed to, for example, 20 seconds or less, and can be suppressed to 8 seconds or less at around room temperature. Therefore, even if fluctuation occurs over a long period of time, such as 21 days, a large error does not accumulate, and accurate timekeeping is possible through subsequent correction processing.

[0136] In the above embodiment, the processes of S33 and S34 in Fig. 10 are a specific example of first time difference calculation means, the process of S38 in Fig. 10 is a specific example of reference time difference calculation means, and the processes of S39 to S43 in Fig. 10 are a specific example of correction means. The process of S39 in Fig. 10 is a specific example of second time difference calculation means, and the processes of S40 to S43 in Fig. 10 are 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 cancels out the average value of the past difference values ​​A2. Even in this case, the master RTC 3 can be controlled to reduce fluctuations in the AC signal.

[0138] However, if the 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 for the time to reach a certain level.In contrast, if the amplitude of the AC signal error is doubled, the RTC fluctuation will increase and the fluctuation of the correction value C will also increase significantly.

[0139] The pseudo standard radio wave output unit 24 is not limited to outputting a 40 kHz pseudo standard radio wave, and may output a 60 kHz pseudo standard radio wave. 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 time signal output unit 24 to output a pseudo standard time signal at 40 kHz. This allows the pseudo standard time signal output unit 24 to output a pseudo standard time signal at 40 kHz every predetermined period. The slave controller 30 may also be configured to cause the pseudo standard time signal output unit 24 to output a pseudo standard time signal at 60 kHz.

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

[0142] In the above embodiment, the pseudo standard radio wave transmission process of slave unit 11 involves correcting the time of slave unit RTC 21 and outputting a pseudo standard radio wave after acquiring a 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 it is not possible to acquire a time information signal (standard radio wave data) from master unit 1, slave unit 11 may output a pseudo standard radio wave as long as the time of slave unit RTC 21 has already been corrected.

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

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

Claims

1. A radio-controlled clock repeater including a master unit that transmits a time information signal according to 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 device is A parent real-time clock that keeps 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 the difference between a first time value measured based on the periodicity of a voltage waveform from a commercial AC power supply at predetermined time intervals 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 the plurality of 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 measured by the master real-time clock;

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

3. The time kept by the master real-time clock is made earlier or later depending on the correction value, the correction value includes a vibration suppression term and a feedback term, The time adjustment means as a first determination situation, when the previous second time difference was a positive value and the current second time difference has increased in a positive direction, the feedback term is set to a unit correction amount in a direction that advances the time; as a second determination situation, 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 the 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 When the second time difference is smaller than a predetermined threshold value, the correction value is set so that the second time difference decreases; 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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