Electronic watch

Abstract

To provide an electronic watch that can improve the accuracy of time.SOLUTION: An electronic watch 100 comprises: an oscillator 200; a clock output unit 20 that generates a clock signal; a temperature measurement unit 30a that intermittently measures the peripheral temperature of the oscillator, and performs output according to the measured temperature for every measurement; a storage unit 40 that stores a first storage value corresponding to the measured temperature as time-series data; and a control unit 50 having a clocking unit 51 that clocks time on the basis of the clock signal, an estimation unit 52 that estimates the oscillatory frequency of the oscillator in a section SC of the time-series data of the first storage value stored in the storage unit or a change in the peripheral temperature on the basis of the time-series data of the first storage value, and a first correction unit 53a that, on the basis of either one of the oscillatory frequency of the oscillator or the change in the peripheral temperature estimated in the section, calculates a first time correction amount that is a correction amount for correcting a time error occurring in the section, and performs time correction on the basis of the first time correction amount.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electronic timepiece. [Background technology]

[0002] Conventionally, electronic watches measure the temperature around a quartz crystal unit, estimate changes in the quartz crystal unit's oscillation frequency based on the measured temperature and data showing the quartz crystal unit's frequency-temperature characteristics, and correct the oscillation frequency output from the quartz crystal unit to cancel out the estimated changes, thereby reducing time errors. In electronic watches, the temperature around the quartz crystal unit is measured at regular intervals to reduce power consumption. For example, Patent Document 1 discloses a technology related to an electronic watch that includes a clock IC that generates time data based on a clock from a quartz crystal unit and supplies an interrupt signal to a CPU at regular intervals, a CPU that starts up in response to the interrupt signal from the clock IC, and a temperature measurement unit that measures the temperature around the quartz crystal unit. The CPU periodically calculates the time error based on the temperature measured by the temperature measurement unit and instructs the clock IC to correct the error. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-311173 Summary of the Invention [Problem to be solved by the invention]

[0004] There is room for further improvement in the accuracy of timekeeping in electronic clocks. For example, temperature measurements in electronic clocks are performed at regular intervals, and the oscillation frequency is corrected based on the measured temperature. However, temperature changes during periods when temperature measurements are not being performed are not taken into consideration, which can result in time errors.

[0005] An object of the present invention is to provide an electronic timepiece that can improve the accuracy of timekeeping. [Means for solving the problem]

[0006] The electronic timepiece of the present invention comprises an oscillator, a clock output unit that generates a clock signal based on the oscillation frequency of the oscillator, a temperature measurement unit that intermittently measures the ambient temperature of the oscillator and outputs an output according to the measured temperature for each measurement, a memory unit that stores a first memory value corresponding to the measured temperature as time series data based on the output from the temperature measurement unit, and a control unit, wherein the control unit comprises a timekeeping unit that measures time based on the clock signal, an estimation unit that estimates, based on the time series data of the first memory values, the change in the oscillation frequency of the oscillator or the ambient temperature of the oscillator in a section between at least two consecutive first memory values ​​in the time series data of the first memory values ​​stored in the memory unit, and a first correction unit that calculates a first time correction amount, which is a correction amount that corrects the time error that occurs in the section, based on either the estimated oscillation frequency of the oscillator or the change in the ambient temperature of the oscillator in the section, and performs time correction based on the first time correction amount. [Effects of the Invention]

[0007] The electronic timepiece according to the present invention has the effect of improving the accuracy of the time. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a conceptual diagram showing an electronic timepiece according to an embodiment. [Figure 2] FIG. 2 is a graph showing an example of time correction in the electronic timepiece according to the embodiment. [Figure 3] FIG. 3 is a flowchart illustrating an example of the time correction process in the electronic timepiece according to the embodiment. [Figure 4] FIG. 4 is a diagram showing an example of a data flow of the time correction process in the electronic timepiece according to the embodiment. [Figure 5]FIG. 5 is a conceptual diagram showing an electronic timepiece according to a first modified example of the embodiment. [Figure 6] FIG. 6 is a graph showing an example of time correction in an electronic timepiece according to a first modified example of the embodiment. [Figure 7] FIG. 7 is a conceptual diagram showing an electronic timepiece according to a second modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A wristwatch according to an embodiment of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to this embodiment. Furthermore, the components in the following embodiments include those that would be easily conceivable to a person skilled in the art or that are substantially identical.

[0010] [Embodiment] An embodiment will be described with reference to Fig. 1 to Fig. 4. The embodiment relates to an electronic timepiece. Fig. 1 is a conceptual diagram showing an electronic timepiece according to an embodiment, Fig. 2 is a graph showing an example of time correction in the electronic timepiece according to an embodiment, Fig. 3 is a flowchart showing an example of time correction processing in the electronic timepiece according to an embodiment, and Fig. 4 is a diagram showing an example of the data flow of the time correction processing in the electronic timepiece according to an embodiment.

[0011] The electronic timepiece 100 according to this embodiment is a wristwatch worn by a user. As shown in Fig. 1, the electronic timepiece 100 according to this embodiment includes a vibrator 200, a clock output unit 20, a temperature measurement unit 30a, a memory unit 40, and a control unit 50.

[0012] The oscillator 200 is a clock source for measuring time, and may be a quartz oscillator or a resonator based on MEMS (Micro Electro Mechanical Systems). The quartz oscillator 10 is a U-shaped quartz oscillator with two rod-shaped vibrating prongs connected at the ends by a single joint. That is, the quartz oscillator 10 of this embodiment is a tuning fork-type quartz oscillator. The quartz oscillator 10 vibrates when a voltage is applied from a power supply (not shown) via an oscillation circuit (described later). The MEMS resonator is formed of silicon, vibrates mechanically due to an electrostatic field excitation force, and generates an electrical signal at a specific frequency using an oscillation maintenance circuit. In the following embodiments, the oscillator 200 will be described as using the quartz oscillator 10, but this is not limiting. A MEMS resonator may also be used for the oscillator 200, and similar effects can be obtained. Similar effects can also be obtained with an oscillator incorporating a quartz oscillator or a MEMS resonator.

[0013] The clock output unit 20 is a component that generates a clock signal based on the oscillation frequency of the crystal unit 10. In this embodiment, the clock output unit 20 includes an oscillation circuit and a frequency divider circuit. The oscillation circuit generates a source oscillation using the oscillation of the crystal unit 10, and the frequency divider circuit generates a clock signal by dividing the reference signal output from the oscillation circuit, and outputs the generated clock signal to the control unit 50.

[0014] The temperature measurement unit 30a is a component that intermittently measures the temperature around the crystal unit 10 and outputs a value corresponding to the measured temperature to the control unit 50 for each measurement. The temperature measurement unit 30a is, for example, a CR oscillator. In this embodiment, the temperature measurement unit 30a periodically (for example, every 30 seconds) measures the temperature around the crystal unit 10 and outputs a value corresponding to the measured temperature to the control unit 50.

[0015] The storage unit 40 is a component that stores various programs required for the operation of the electronic timepiece 100 and various data related to the operation of the electronic timepiece 100. In this embodiment, the storage unit 40 includes RAM (Random Access Memory) and ROM (Read Only Memory). The storage unit 40 stores first stored values ​​corresponding to the measured temperature around the crystal unit 10 as time-series data based on the output from the temperature measurement unit 30a. In this embodiment, the control unit 50 converts the output from the temperature measurement unit 30a according to the measured temperature into an oscillation frequency value when the crystal unit 10 oscillates at that measured temperature, and stores the converted first stored values ​​P1 to P7 in the storage unit 40. That is, the storage unit 40 stores the first stored values ​​P1 to P7 corresponding to the output from the temperature measurement unit 30a as time-series data. The storage unit 40 also stores a table, as frequency-temperature characteristic data, that associates the temperature value of the crystal unit 10 with the oscillation frequency value of the crystal unit 10 at each temperature value. Here, the first stored values ​​P1 to P7 that the control unit 50 stores in the storage unit 40 are not limited to the oscillation frequency of the crystal unit 10 converted to the measured temperature, but may be the ambient temperature value of the crystal unit 10 measured by the temperature measurement unit 30a. In this case, the calculation of the correction amount for the oscillation frequency is performed after converting the measured temperature value into an oscillation frequency value based on the frequency-temperature characteristic data, for example.

[0016] The control unit 50 is a component that controls the electronic timepiece 100. The control unit 50 includes a CPU (Central Processing Unit). The control unit 50 measures the internal time of the electronic timepiece 100 based on the clock signal output from the clock output unit 20, controls the display on the display unit (not shown), and outputs control signals corresponding to each function. In addition, the control unit 50 of this embodiment receives, for example, the output from the temperature measurement unit 30a as a temperature value and converts the temperature value into an oscillation frequency value when the crystal unit 10 vibrates at that temperature value. For example, the control unit 50 reads frequency-temperature characteristic data stored in the memory unit 40 and, based on the frequency-temperature characteristic data, converts the temperature value corresponding to the output from the temperature measurement unit 30a into an oscillation frequency value when the crystal unit 10 vibrates at that temperature value. The control unit 50 then stores the converted oscillation frequency value as a first stored value in the memory unit 40 as time-series data for each measurement by the temperature measurement unit 30a.

[0017] In the electronic timepiece 100 according to this embodiment, the clock output unit 20 generates a clock signal based on the oscillation frequency (reference frequency B1) of the crystal unit 10 at a reference temperature (e.g., 25°C). If the temperature of the crystal unit 10 changes from the reference temperature, the oscillation characteristics of the crystal unit 10 change. This change also causes the oscillation frequency of the crystal unit 10 to change from the reference frequency B1 (see FIG. 2). If the oscillation frequency of the crystal unit 10 changes from the reference frequency B1, the clock output unit 20 generates a clock signal based on a frequency different from the reference frequency B1, resulting in an error in the time displayed by the electronic timepiece 100.

[0018] The control unit 50 of the embodiment performs time correction (temperature compensation) of the electronic watch 100 using the first memory value stored in the memory unit 40. In the embodiment, the control unit 50 performs time correction (temperature compensation) at regular intervals (every 60 seconds). As shown in FIG. 1, the control unit 50 of the embodiment conceptually includes a timing unit 51, an estimation unit 52, a first correction unit 53a, and an interval designation unit 54.

[0019] The timing unit 51 is a component that measures the time to be displayed on a display unit (not shown) of the electronic timepiece 100. The timing unit 51 measures the time by counting pulses included in the clock signal from the clock output unit 20. In other words, the timing unit 51 measures the time based on the clock signal from the clock output unit 20.

[0020] One way to keep the oscillation frequency of the crystal unit 10 constant when the temperature of the crystal unit 10 changes is to intermittently measure the oscillation frequency of the crystal unit 10, detect the difference between the oscillation frequency (reference frequency B1) of the crystal unit 10 at a reference temperature (e.g., 25°C) at the time of measurement (present time), and then increase or decrease the oscillation frequency to correct for that difference. However, this method only corrects the oscillation frequency at the time of measurement (present time), and does not correct for changes in the oscillation frequency during times when measurements are not being taken. Because time is measured by counting (accumulating) clock signals, the accuracy of the timekeeping is reduced due to the influence of periods when the oscillation frequency was not corrected.

[0021] In this embodiment, the first stored values ​​P1 to P7, which store the measured oscillation frequency as time-series data, are used to estimate the oscillation frequency between the first stored values ​​where the oscillation frequency has not been measured, and the difference between the reference frequency B1 and the estimated oscillation frequency is detected, and the oscillation frequency is increased or decreased to correct the difference, thereby enabling highly accurate timekeeping to be continued.

[0022] Furthermore, since the changes in oscillation frequency of the first stored values ​​P1 to P7, which are oscillation frequencies measured in the past, are fixed, it is possible to accurately estimate the oscillation frequency between the first stored values, thereby minimizing errors in timekeeping.

[0023] The accuracy of timekeeping in a watch is evaluated by measuring the time error over a certain period of time, such as monthly or annual difference, so there is no need to immediately correct the oscillation frequency of crystal oscillator 10 when a change in the ambient temperature of crystal oscillator 10 is detected. Rather, by understanding the changes in temperature or oscillation frequency in detail relative to the temperature or oscillation frequency of crystal oscillator 10 in the time series data recorded over a certain period of time in the past, and making a time-delayed correction to cancel out the deviation from reference frequency B1, the total time accuracy over a certain period of time can be improved.

[0024] The estimation unit 52 is a component that estimates a change in the oscillation frequency of the crystal unit 10 in an interval SC (see FIG. 2) between at least two consecutive first stored values ​​in the time-series data of the first stored values ​​stored in the storage unit 40. Here, the "time-series data of the first stored values" refers to a series of first stored values ​​(a series of first stored values) obtained by the temperature measurement unit 30a intermittently measuring the temperature. Here, the estimation unit 52 estimates a change in the oscillation frequency of the crystal unit 10. However, since the oscillation frequency changes due to changes in the temperature around the crystal unit 10, the estimation unit 52 may store temperature values ​​as time-series data of the first stored values, estimate the change in the temperature values, and convert the temperature values ​​into oscillation frequency values ​​in the process of calculating the correction amount for the oscillation frequency. The estimation unit 52 estimates a change in the oscillation frequency of the crystal unit 10 in the interval SC from the time-series data of the first stored values ​​stored in the storage unit 40 using techniques such as linear interpolation, spline interpolation, Bayesian estimation, and LPF (Low-pass filter). Furthermore, when the estimation unit 52 estimates the change in the oscillation frequency of the crystal resonator 10 in the section SC, if the number of first stored values ​​included in the time-series data of the first stored values ​​is relatively large, estimation using a moving average, removal of outliers, consideration of the heat capacity of the oscillation circuit, etc. may be performed.

[0025] 2, the estimation unit 52 of the embodiment estimates a change in the oscillation frequency of the crystal resonator 10 in a section SC that includes the first stored values ​​P3 to P5, based on the first stored values ​​P1 to P7. In the embodiment, the first stored values ​​P1 to P7 are stored as time-series data at 30-second intervals.

[0026] The embodiment will be described in detail below.

[0027] As an example, the section SC is a section from one minute before the current time to two minutes before the current time in the time series data of the first stored values ​​P1 to P7, and is a section that includes the first stored values ​​P3 to P5. For example, the estimation unit 52 estimates a change C1 in the oscillation frequency of the crystal resonator 10 based on the first stored values ​​P1 to P7 in a section wider than the section SC that includes the section SC, and calculates estimated frequency values ​​Q1 to Q6 between the first stored values ​​P3 to P5 from the change C1 in the oscillation frequency of the crystal resonator 10. That is, the estimation unit 52 in this embodiment estimates (upsamples) the oscillation frequency values ​​of the crystal resonator 10 at time intervals that are shorter than the measurement period of the first stored values ​​in the section SC, based on the time series data of the first stored values ​​P1 to P7, and calculates the estimated frequency values.

[0028] In this embodiment, the estimation unit 52 calculates oscillation frequency values ​​(estimated frequency values ​​Q1 to Q6) at 10-second intervals during the interval SC. That is, the estimation unit 52 estimates changes in the oscillation frequency of the crystal resonator 10 during the interval SC based on time-series data of the first stored values ​​P1 to P7, which are the results of past temperature measurements stored in the storage unit 40, and calculates the estimated frequency values ​​Q1 to Q6 during the interval SC. This allows for more accurate time-series data of oscillation frequency values ​​during the interval SC without narrowing the measurement interval of the temperature measurement unit 30a. While shortening the measurement cycle (interval) of the temperature measurement unit 30a to increase the number of measurements would also improve the detectability of changes in the oscillation frequency, the increased number of measurements would increase power consumption. According to this embodiment, it is possible to measure time with high accuracy while maintaining the same measurement cycle as before.

[0029] The first correction unit 53a in this embodiment is a component that performs temperature compensation for the oscillation frequency of the crystal unit 10. Based on the change in the oscillation frequency of the crystal unit 10 estimated in the section SC, the first correction unit 53a calculates a first time correction amount, which is a correction amount for correcting the time error caused by the change in the oscillation frequency of the crystal unit 10 in the section SC, and outputs a first time correction signal corresponding to the first time correction amount to the clock output unit 20, thereby performing temperature compensation for the oscillation frequency of the crystal unit 10. Here, the change in the oscillation frequency of the crystal unit 10 refers to the change in the oscillation frequency of the crystal unit 10 relative to the reference frequency B1.

[0030] As shown in FIG. 2, in the first embodiment, the temperature measurement unit 30a measures the temperature every 30 seconds, and the first correction unit 53a compensates the temperature of the crystal unit 10 every 60 seconds. Here, the timing of temperature measurement and temperature compensation is described as being twice as long as the temperature measurement, but this is not limiting. The timing of temperature measurement and temperature compensation may be determined based on the power consumption and the power balance of the clock when each unit operates, or the storage capacity for recording the measurement data. For example, if there is a margin in the power balance, the temperature measurement and temperature compensation may be performed at the same timing (same period). However, if there is a margin in the power balance, the period for performing temperature compensation may be longer than the period for temperature measurement to reduce the impact of power consumption on the power balance due to temperature compensation.

[0031] In the embodiment, the first correction unit 53a calculates a correction amount (first time correction amount E1) for correcting a time error caused by a deviation of each estimated frequency value Q1 to Q6 from the reference frequency B1. Specifically, the first correction unit 53a calculates the deviation of each estimated frequency value Q1 to Q6 from the reference frequency B1, calculates a correction amount to cancel out the time error caused by each calculated deviation, and calculates the first time correction amount E1 by adding up these correction amounts. The first correction unit 53a outputs a first time correction signal corresponding to the first time correction amount E1 to the clock output unit 20 and corrects the clock signal output from the clock output unit 20, thereby correcting the time. The above time correction process is performed at each temperature correction timing. This allows the clock signal to be corrected for deviations in the oscillation frequencies of Q2 and Q3 between the first memory values ​​P3 and P4 in FIG. 2 and Q6 and Q7 between the first memory values ​​P4 and P5, improving time accuracy. In the embodiment, the first time correction amount is calculated using time series data of estimated frequency values ​​Q1 to Q6 at 10-second intervals, but the accuracy of the time correction can be improved by narrowing the intervals between the time series data of estimated frequency values ​​Q1 to Q6.

[0032] Here, the first correction unit 53a of the embodiment may store a fractional correction amount smaller than the minimum resolution of the clock output unit 20 in the storage unit 40, and at the next or subsequent predetermined time correction (for example, the next time correction), read the fractional correction amount from the storage unit 40 and include it in the first time correction amount E1 at that time. That is, the first correction unit 53a of the embodiment may carry over a fractional correction amount smaller than the minimum resolution of the clock output unit 20 and reflect it in the next or subsequent time correction. This configuration enables even higher accuracy correction. The first correction unit 53a may also store the calculated first time correction amount E1 in the storage unit 40 as time-series data.

[0033] The correction value used by the control unit 50 to correct the oscillation frequency for the clock output unit 20 is equal to or greater than the minimum resolution of the circuit that generates the clock signal in the clock output unit 20, with the minimum value being in units of 100 ppb, for example. In other words, the correction value output to the clock output unit 20 is a discrete value, and correction amounts less than the minimum resolution (100 ppb) are rounded up or down, resulting in quantization error. Therefore, when the correction value is equal to or greater than the minimum resolution of the clock output unit 20, the oscillation frequency is corrected by adding or subtracting an adjustment value based on the correction amount. Fractional correction amounts smaller than the minimum resolution are recorded and carried over, and when the accumulated fractional correction value (cumulative fractional correction value) is equal to or greater than the minimum resolution, the oscillation frequency is corrected by adding or subtracting an adjustment value based on the fractional correction value. This allows the electronic timepiece 100 according to this embodiment to reduce timekeeping errors.

[0034] When the cumulative total of the fractional correction values ​​is reflected in the correction value (first time correction amount) of the oscillation frequency, the first correction unit 53a updates the cumulative total of the fractional correction values ​​with a residual value (the residual value of the first time correction that could not be included in the first time correction amount) obtained by subtracting the adjustment value from the cumulative total of the fractional correction values. Here, the process of accumulating the fractional correction values ​​and the determination of whether the cumulative total of the fractional correction values ​​is equal to or greater than the minimum resolution of the correction value of the oscillation frequency are performed every time temperature compensation is performed, but this is not limited to this. The first correction unit 53a may perform the process of accumulating the fractional correction values ​​and the determination of whether the cumulative total of the fractional correction values ​​is equal to or greater than the minimum resolution of the correction value of the oscillation frequency at the timing of temperature measurement, or may perform these processes collectively at a cycle shorter than the cycle of temperature compensation.

[0035] Similarly, the temperature measurement unit 30a also generates quantization errors, affecting the accuracy of timekeeping. The temperature measurement unit 30a detects the temperature of the crystal unit 10 using a temperature measurement circuit and outputs the digital signal to the control unit 50. Specifically, an analog signal indicating the measured temperature is compared with multiple comparison values ​​prepared at regular intervals, and a value based on the appropriate comparison value is output as a digital signal to the control unit 50. In other words, the measured analog temperature value is converted into a discrete value, resulting in fractional values ​​being rounded down or up (quantization error). Therefore, the digital temperature value output to the control unit 50 cannot represent a value smaller than the minimum resolution. Because the clock signal is corrected based on the difference between the oscillation frequency converted from the digital temperature signal and the reference frequency B1, the difference between the oscillation frequency value calculated from the digital temperature signal and the true measured oscillation frequency value is not corrected, affecting the accuracy of timekeeping.

[0036] In this embodiment, to solve the above problem, the estimated frequency value is calculated as described above, and the difference between the oscillation frequency value and the estimated frequency value (temperature resolution correction value) is recorded. Based on this, in this embodiment, to solve the above problem, the first correction unit 53a performs time correction by outputting a first time correction signal corresponding to the first time correction amount to the clock output unit to correct the clock signal, and stores in the memory unit 40 a temperature resolution correction value that is smaller than the minimum resolution of the temperature measurement unit 30a for the temperature resolution correction value, which is the difference between the first stored value that stores the frequency based on the temperature value of the digital signal and the estimated frequency value estimated based on the time series data of the first stored value.Then, at the next or subsequent time correction by the first correction unit (for example, the next time), the temperature resolution correction value is included in the first time correction amount, and the oscillation frequency is corrected.

[0037] When correcting the oscillation frequency using a temperature resolution correction value that is smaller than the minimum resolution of the temperature measurement unit 30a, the temperature resolution correction value can be recorded and carried over as described above, and the oscillation frequency can be corrected at the temperature correction timing when the accumulated value carried over exceeds the minimum resolution, or the oscillation frequency can be corrected when the total value of the temperature resolution correction value over a predetermined period is greater than the minimum resolution. In other words, the temperature resolution correction value that could not be reflected in the correction amount is not discarded but is stored as a temperature resolution correction value residual value and used to correct the oscillation frequency, so that even minute deviations in the oscillation frequency can be corrected, enabling highly accurate timekeeping.

[0038] The specific details will be explained below.

[0039] In Figure 2, the estimated frequency value Q4, derived from the transition of the first stored values ​​of three or more consecutive measurements, is slightly lower than the first stored value P4. This is because the first stored value P4 is rounded due to the quantization error in the temperature measurement mentioned above. The estimated frequency value Q4 is calculated from the transition of the first stored values ​​P3, P4, and P5, and is not rounded. This value is closer to the true oscillation frequency. This results in a difference between the first stored value P4 and the estimated frequency value Q4. This difference (temperature resolution correction value) often falls short of the minimum resolution. Therefore, the temperature resolution correction value is recorded and accumulated. When the accumulated temperature resolution correction value is equal to or greater than the minimum resolution of the correction value, the adjustment value is added or subtracted from the oscillation frequency correction value based on the temperature resolution correction value to correct the oscillation frequency. This reduces timing errors.

[0040] When the cumulative temperature resolution correction value is reflected in the oscillation frequency correction value (first time correction amount), the residual value (the residual value of the temperature resolution correction value that could not be included in the first time correction amount) obtained by subtracting the adjustment value from the cumulative temperature resolution correction value may be updated as the cumulative temperature resolution correction value. Here, the process of accumulating the temperature resolution correction value and the determination of whether the cumulative temperature resolution correction value is equal to or greater than the minimum resolution of the oscillation frequency correction value are performed every time temperature compensation is performed, but this is not limited to this. They may be performed at the timing of temperature measurement, or may be performed collectively at a cycle shorter than the temperature compensation cycle.

[0041] In Figure 2, the oscillation frequency is estimated from three first stored values ​​P3, P4, and P5 using the estimation method described above at intervals shorter than the measurement interval of the oscillation frequency (or temperature), to obtain estimated frequency values ​​Q1 to Q6. When estimating the estimated frequency values ​​Q1 to Q6, the temperature inside the watch changes slowly because it is sealed by the watch case, and it is possible to express the change in oscillation frequency as a linear or quadratic function on the time scale of the measurement intervals described above. Here, the calculation of the estimated frequency values ​​Q1 to Q6 may use more than three first stored values, which allows a greater understanding of the transition trends in fluctuations in the oscillation frequency (or temperature), thereby improving the calculation accuracy of the estimated frequency values.

[0042] The cumulative total of the fractional correction values ​​and the cumulative total of the temperature resolution fractional values ​​may be independently determined to be equal to or greater than the minimum resolution of the correction value, or the cumulative total of the fractional correction values ​​and the cumulative total of the temperature resolution fractional values ​​may all be combined to form a cumulative total, and a determination may be made as to whether the cumulative total is equal to or greater than the minimum resolution of the oscillation frequency correction value. If the cumulative total is equal to or greater than the minimum resolution of the oscillation frequency correction value, the oscillation frequency is corrected by adding or subtracting an adjustment value based on the cumulative total. When the cumulative total is reflected in the oscillation frequency correction value, the adjustment value is subtracted from the cumulative total, and the remaining value is updated as the cumulative total.

[0043] Furthermore, at the timing of temperature compensation, the fractional correction value and the temperature resolution fractional value may be added together to obtain a fractional total value, and this fractional total value may be stored and accumulated to obtain a cumulative total value, and a determination may be made as to whether the cumulative total value is equal to or greater than the minimum resolution of the oscillation frequency correction value.

[0044] The recording of the above-mentioned cumulative fractional correction value and temperature resolution fractional value may be omitted depending on the contribution of the cumulative fractional correction value and temperature resolution fractional value to the oscillation frequency correction amount or the circuit size and configuration of the clock output unit 20, temperature measurement unit 30a, and control unit 50. Storing the cumulative fractional correction value and temperature resolution fractional value as time-series data requires a corresponding amount of storage capacity in the memory unit 40, which may increase the circuit area in the electronic watch and affect its size. In this case, the storage capacity of the memory unit 40 can be avoided by not recording the fractional value of either the correction amount fractional value or the fractional value based on the temperature resolution, whichever fractional value results in the smaller amount of oscillation frequency correction.

[0045] Up to now, an embodiment has been described in which three first stored values ​​P3, P4, and P5 are used to calculate the estimated frequency values ​​Q1 to Q6. However, it is also possible to calculate the estimated frequency values ​​using only two first stored values ​​P3 and P4. In this case, the accuracy of correction for the oscillation frequency is reduced compared to when three first stored values ​​are used. This is because the estimated frequency value is estimated only based on the transitions of the first stored values ​​P3 and P4, and the estimated frequency value becomes uncertain relative to the value of the first stored value P4, which is rounded due to quantization error.

[0046] Specifically, we will explain this using two first stored values: first stored value P7 and first stored value P6. The estimated frequency value between first stored value P7, which is the oscillation frequency at the current time, and the immediately preceding first stored value P6 is calculated. However, because there are no oscillation frequency measurements beyond (in the future) first stored value P7, it is not possible to find an interpolated line for calculating the first stored value P7 and an estimated frequency value near first stored value P7, making it difficult to predict the true oscillation frequency. Therefore, the estimated frequency value at P7 must be set equal to first stored value P7, which includes deviations due to quantization errors. Therefore, to minimize errors in the clocked time, it is desirable to calculate the estimated frequency value using first stored values ​​from three or more consecutive past points in the time-series data, without including the current oscillation frequency measurement value.

[0047] In other words, by calculating an estimated frequency from two or more first stored values, which are the oscillation frequency values ​​of the time series data, and correcting the oscillation frequency, it is possible to maintain highly accurate timekeeping, and by calculating an estimated frequency using three or more first stored values ​​and correcting the oscillation frequency, the accuracy of timekeeping can be further improved.

[0048] The interval designation unit 54 is a component that designates an interval SC that is a preset time before the current time. In the embodiment, the interval designation unit 54 is configured to designate an interval SC that extends from one minute before the current time to two minutes before the current time. The interval designation unit 54 is also configured to designate an interval that is wider than the interval SC and that includes the interval SC, for estimating the change C1 in the oscillation frequency of the crystal resonator 10. In the embodiment, the interval designation unit 54 is configured to include one minute before and after the interval SC in an interval that is wider than the interval SC and includes the interval SC.

[0049] Next, an example of the flow of the time correction process in the electronic timepiece 100 according to this embodiment will be described with reference to FIG.

[0050] 3, the control unit 50 of the electronic timepiece 100 according to the embodiment determines whether the current time is the timing for temperature measurement by the temperature measurement unit 30a (step S1). If the current time is not the timing for temperature measurement by the temperature measurement unit 30a, the control unit 50 executes step S1 again.

[0051] If the current time is the timing for temperature measurement by the temperature measurement unit 30a, the control unit 50 controls the temperature measurement unit 30a to measure the temperature around the crystal unit 10 and stores a first memory value corresponding to the output of the temperature measurement unit 30a according to the measured temperature as time-series data in the memory unit 40. In this embodiment, the control unit 50 executes temperature measurement by the temperature measurement unit 30a every 30 seconds. The control unit 50 then determines whether the current time is the timing for temperature compensation (time correction timing) for the oscillation frequency of the crystal unit 10 (step S3). If the current time is not the timing for temperature compensation for the oscillation frequency of the crystal unit 10, the control unit 50 returns to step S1 and continues the process.

[0052] If the current time is the timing for temperature compensation of the oscillation frequency of the crystal unit 10, the control unit 50 reads out past measurement results (time-series data of first stored values) stored in the storage unit 40 (step S4). The control unit 50 then estimates changes in the oscillation frequency of the crystal unit 10 during a past interval SC in the time-series data of the first stored values ​​(step S5). The control unit 50 then calculates the frequency error (deviation of the oscillation frequency from the reference frequency) that occurred during the past interval SC based on the changes in the oscillation frequency of the crystal unit 10 during that interval SC (step S6). The control unit 50 then calculates an adjustment value (first time correction amount) that cancels out the frequency error that occurred during the interval SC (step S7).

[0053] The control unit 50 outputs a first time correction signal corresponding to the calculated first time correction amount to the clock output unit 20. The clock output unit 20 generates a clock signal in which the time error that occurred in the section SC has been corrected using the first time correction signal input from the control unit 50. The corrected clock signal is output to the control unit 50. (Step S8)

[0054] The control unit 50 then determines whether to continue the processing (step S9). If the control unit 50 determines to continue the processing, it executes the time correction processing again from step S1. If the control unit 50 determines not to continue the processing, it ends the time correction processing. Here, the control unit 50 determines not to continue the processing if, for example, the user of the electronic watch 100 performs an operation to stop the time correction function, and determines to continue the processing if the user has not performed an operation to stop the time correction function.

[0055] The electronic timepiece 100 according to the embodiment executes the time correction process as described above. Because the electronic timepiece 100 according to the embodiment delays and corrects changes in the oscillation frequency of the quartz crystal unit 10 due to temperature changes, past measurement results can be used for temperature compensation of the oscillation frequency of the quartz crystal unit 10. This configuration enables upsampling of temperature measurement results from past intervals, enabling more accurate time correction. Therefore, the electronic timepiece 100 according to the embodiment can improve the accuracy of the time.

[0056] Next, an example of the data flow in the time correction process in the electronic timepiece 100 according to this embodiment will be described with reference to FIG.

[0057] The control unit 50 periodically stores the temperature measurement results (first stored values) of the temperature measurement unit 30a in the storage unit 40 and creates a measurement result history P. The control unit 50 then reads from the storage unit 40 time-series data of the first stored values ​​for past intervals included in the measurement result history P. Here, the control unit 50 reads from the storage unit 40 the time-series data of the first stored values ​​P3 to P5 for past intervals SC. The control unit 50 calculates highly accurate estimated frequency values ​​Q1 to Q6 for the past intervals SC by interpolating (upsampling) the time-series data of the first stored values ​​P3 to P5 read from the storage unit 40. The control unit 50 calculates an error E0 in the oscillation frequency of the crystal unit 10 that occurred within the past interval SC from the highly accurate estimated frequency values ​​Q1 to Q6 for the past interval SC, inverts the sign of the calculated error E0 in the oscillation frequency of the crystal unit 10, and calculates a first time correction amount E1 that cancels out the error E0. The control unit 50 outputs a first time correction signal corresponding to the calculated first time correction amount E1 to the clock output unit 20, and corrects the clock signal output from the clock output unit 20, thereby performing time correction.

[0058] An example of the data flow in the time correction process in the electronic timepiece 100 according to this embodiment has been described above.

[0059] As described above, the electronic timepiece 100 according to the embodiment includes the oscillator 200, the clock output unit 20 that generates a clock signal based on the oscillation frequency of the oscillator 200, the temperature measurement unit 30a that intermittently measures the ambient temperature of the oscillator 200 and outputs an output according to the measured temperature for each measurement, the memory unit 40 that stores the measured temperature and the corresponding first stored value as time-series data based on the output from the temperature measurement unit 30a, and the control unit 50. The control unit 50 also includes a timekeeping unit 51 that keeps time based on the clock signal, and a time output unit 20 that outputs the time of the first stored value stored in the memory unit 40. The control unit 50 includes an estimation unit 52 that estimates a change in the oscillation frequency of the oscillator 200 or the ambient temperature of the oscillator 200 in an interval SC between at least two consecutive first memory values ​​in the series data based on the time series data of the first memory values, and a first correction unit 53a that calculates a first time correction amount E1, which is a correction amount for correcting a time error that occurs in the interval SC, based on either the estimated oscillation frequency of the oscillator 200 or the change in the ambient temperature of the quartz oscillator in the interval SC, and performs time correction based on the first time correction amount E1.

[0060] In the electronic timepiece 100 according to the embodiment, the estimation unit 52 estimates the change in the oscillation frequency of the vibrator 200 or the ambient temperature of the vibrator 200 during the interval SC based on the first stored value stored in the memory unit 40. The first correction unit 53a calculates a first time correction amount E1 based on the estimated change in the oscillation frequency of the vibrator 200 or the ambient temperature of the vibrator 200, and corrects the time based on the first time correction amount E1. This configuration enables the electronic timepiece 100 according to the embodiment to perform more precise time correction. For example, compared to generating a time correction signal based solely on the first stored value, the influence of time errors caused by temperature changes during periods when temperature measurement is not performed can be reduced. Furthermore, by estimating the change in the oscillation frequency of the vibrator 200 during the interval SC based on the first stored value, the accuracy of the time correction can be improved without increasing the measurement frequency of the temperature measurement unit 30a. In other words, the electronic timepiece 100 according to the embodiment can improve the accuracy of the time while reducing the power consumption of the temperature measurement unit 30a.

[0061] Furthermore, in the electronic clock 100 according to the embodiment, the first correction unit 53a performs time correction by outputting a first time correction signal corresponding to the first time correction amount to the clock output unit 20 to correct the clock signal, stores a first fractional correction amount that is smaller than the minimum resolution of the clock output unit 20 for the first time correction amount in the memory unit 40, and includes the first fractional correction amount in the first time correction amount at the next or subsequent specified time correction by the first correction unit 53a (for example, at the next time correction).

[0062] When correcting the oscillation frequency at the next and subsequent time corrections using a first fractional correction amount that is smaller than the minimum resolution of the clock output unit 20, as described above, the first fractional correction amount may be accumulated and the oscillation frequency may be corrected at the timing of temperature correction when the accumulated value exceeds the minimum resolution, or the oscillation frequency may be corrected when the total value of the fractional correction values ​​over a predetermined period is greater than the minimum resolution. In other words, the residual fractional value that could not be reflected in the correction amount is not discarded but is stored as a first time correction residual amount and used to correct the oscillation frequency, so that even minute deviations in the oscillation frequency can be corrected, enabling highly accurate timekeeping.

[0063] The electronic timepiece 100 according to the embodiment can reflect a fractional correction amount smaller than the minimum resolution of the clock output unit 20 in the next or subsequent predetermined time correction. This configuration allows the electronic timepiece 100 according to the embodiment to further improve the time accuracy.

[0064] Furthermore, in the electronic watch 100 according to the embodiment, the first correction unit 53a performs time correction by outputting a first time correction signal corresponding to the first time correction amount to the clock output unit 20 and correcting the clock signal, and stores in the memory unit 40 a temperature resolution correction value that is smaller than the minimum resolution of the temperature measurement unit 30a for a temperature resolution correction value that is the difference between the first stored value and a value estimated based on time series data of the first stored value, and at the next or subsequent specified time correction, includes the temperature resolution correction value in the first time correction amount at the specified time correction.

[0065] The electronic timepiece 100 according to this embodiment can reflect a temperature resolution correction value smaller than the minimum resolution of the temperature measurement unit 30a in subsequent time corrections. This configuration allows the electronic timepiece 100 according to this embodiment to further improve the accuracy of the time.

[0066] Furthermore, in the electronic timepiece 100 according to the embodiment, when the first correction unit 53a performs the time correction by incorporating the first fractional correction amount equal to or greater than the minimum resolution of the clock output unit 20 into the first time correction amount, the first correction unit 53a stores in the storage unit 40 a residual value of the first time correction amount that was not reflected in the time correction, and at a predetermined time correction subsequent to the time correction, the residual value of the first fractional correction is included in the first time correction amount at the predetermined time correction.

[0067] In the electronic watch 100 of the embodiment, when the time correction is performed by including a first fractional correction amount in the first time correction amount, the residual value of the first time correction amount that was not reflected in the time correction is included in the first time correction amount at a specified time correction that follows the time correction, thereby further improving the time accuracy.

[0068] Furthermore, in the electronic watch 100 according to the embodiment, when the first correction unit 53a performs the time correction by incorporating the temperature resolution correction value that is equal to or greater than the minimum resolution of the temperature measurement unit 30a into the first time correction amount, the first correction unit 53a stores in the memory unit 40 the residual value of the temperature resolution correction value that was not reflected in the time correction, and at a specified time correction that follows the time correction, includes the residual value of the temperature resolution correction value in the first time correction amount at the specified time correction.

[0069] In the electronic watch 100 of the embodiment, when the time correction is performed by including the temperature resolution correction value of the temperature measurement unit 30a in the first time correction amount, the residual value of the temperature resolution correction value that was not reflected in the time correction is included in the first time correction amount at a specified time correction that follows the time correction, thereby further improving the time accuracy.

[0070] In the above-described embodiment, the first stored value is the oscillation frequency value when the crystal unit 10 vibrates at the temperature measured by the temperature measurement unit 30a. However, this is not limiting. For example, the first stored value may be the temperature value measured by the temperature measurement unit 30a, as described above. In this case, the estimation unit 52 upsamples the temperature value of the crystal unit 10 in the section SC, and then converts it into the oscillation frequency value of the crystal unit 10 corresponding to each temperature value, thereby estimating the change in the oscillation frequency of the crystal unit 10.

[0071] The control unit 50 may also set a range condition for the first stored value, replacing a value outside the range with a value within the range and storing the value in the storage unit 40 as the first stored value. For example, if the upper limit of the range condition for the first stored value, which is a temperature value, is 80°C, the control unit 50 may replace a first stored value corresponding to a measured temperature of 100°C with a first stored value corresponding to a measured temperature of 80°C and store the value in the storage unit 40. The control unit 50 may also set a range condition for the amount of change between previous and next first stored values, replacing a value outside the range with a value within the range and storing the value in the storage unit 40. For example, if the measured temperature corresponding to the first stored value has changed by 10°C or more from the measured temperature corresponding to the previous first stored value, the control unit 50 may replace the value with an average value of the first stored value to be stored and the previous first stored value and store the resulting value in the storage unit 40 as the first stored value. Furthermore, for example, if the measured temperature corresponding to the first stored value has changed by 20°C or more from the measured temperature corresponding to the immediately previous first stored value, the stored first stored value may be replaced with the same value as the immediately previous first stored value and stored as the first stored value in the storage unit 40. This process allows the electronic timepiece 100 according to the embodiment to exclude outliers due to sudden noise, improving the accuracy of time correction.

[0072] The first stored value may also be the deviation (frequency error value) of the crystal unit 10 from the reference frequency B1. In this case, the frequency error value can be calculated, for example, by operating the following mathematical formula (1). In mathematical formula (1), "K0" represents the zero-order temperature coefficient of the crystal unit 10, "K1" represents the first-order temperature coefficient of the crystal unit 10, and "K2" represents the second-order temperature coefficient of the crystal unit 10. In mathematical formula (1), the "temperature difference" represents the temperature value obtained by subtracting the reference temperature (e.g., 25°C) from the temperature value of the crystal unit 10. Frequency error value = K0 + K1 × temperature difference + K2 × temperature difference 2 ··········(1)

[0073] Furthermore, in the above-described embodiment, the section SC is described as a section extending from one minute before the current time to two minutes before the current time, but this is not limited thereto. For example, the section SC may be a section extending from the current time to one minute before the current time. However, as described above, compared to when the section SC calculated by the estimation unit 52a includes the current time, when the section SC calculated by the estimation unit 52a does not include the current time, the first stored values ​​both before and after the section SC can be used for upsampling, thereby enabling more accurate estimation of the change in the oscillation frequency of the crystal resonator 10 during the section SC.

[0074] [First Modification of the Embodiment] A first modified example of an embodiment will be described below. Fig. 5 is a conceptual diagram showing an electronic timepiece according to a first modified example of an embodiment, and Fig. 6 is a graph showing an example of time correction in the electronic timepiece according to the first modified example of an embodiment.

[0075] The first modified embodiment differs from the above embodiment in that the control unit 50 of the electronic timepiece 100 conceptually and functionally further includes a second correction unit 53b, as shown in Figure 5. The rest of the configuration is the same as the above embodiment.

[0076] The second correction unit 53b is a component that instantly corrects the time error caused by the deviation of the oscillation frequency of the crystal unit 10 from the reference frequency B1 during the temperature measurement based on a first stored value corresponding to the measured temperature measured by the temperature measurement unit 30a. In other words, the second correction unit 53b is a component that instantly corrects the time error caused by the deviation of the oscillation frequency of the crystal unit 10 from the reference frequency B1 during the temperature measurement by the temperature measurement unit 30a based on one first stored value obtained during the temperature measurement.

[0077] 6, when the temperature measurement unit 30a measures the measured temperature corresponding to the first stored value P3, the second correction unit 53b calculates a second time correction amount E2, which is a correction amount for correcting a time error caused by a deviation of the oscillation frequency of the crystal unit 10 from the reference frequency B1 between the measurement of the measured temperature corresponding to the first stored value P3 and the next measurement (the measurement of the measured temperature corresponding to the first stored value P4).The second correction unit 53b then immediately outputs a second time correction signal corresponding to the second time correction amount E2 to the clock output unit 20, correcting the clock signal and thereby performing the time correction.In this embodiment, the second correction unit 53b then stores the second time correction amount E2 in the storage unit 40. Thereafter, when the temperature measurement unit 30a measures the measured temperature corresponding to the first stored value P4, the second correction unit 53b calculates a second time correction amount E3, which is a correction amount for correcting the time error caused by the deviation of the oscillation frequency of the crystal unit 10 from the reference frequency B1 between the measurement of the measured temperature corresponding to the first stored value P4 and the next measurement (the measurement of the measured temperature corresponding to the first stored value P5).The second correction unit 53b then immediately outputs a second time correction signal corresponding to the second time correction amount E3 to the clock output unit 20, and performs time correction by correcting the clock signal.In this embodiment, the second correction unit 53b then stores the second time correction amount E3 in the storage unit 40.

[0078] Because the second correction unit 53b calculates the second time correction amount based on only one first stored value, the accuracy is lower than the time correction performed by the first correction unit 53a in the above-described embodiment. For example, in the example shown in FIG. 6, there is an error corresponding to the range indicated by symbols E4 and E5 between the second time correction amounts E2 and E3, which are the correction amounts of the two time corrections performed by the second correction unit 53b, and the actual error resulting from the oscillation frequency of the quartz crystal oscillator 10. Here, the range indicated by symbol E4 is the amount of error calculated from the estimated frequency values ​​Q1 to Q3 calculated between the first stored values ​​P4 and P5, and the range indicated by symbol E5 is the amount of error calculated from the estimated frequency values ​​Q4 to Q7 calculated between the first stored values ​​P5 and P6. In the first modification of the embodiment, the first correction unit 53a delays and corrects this error, thereby improving the accuracy of the time.

[0079] The first correction unit 53a of the first modified embodiment calculates, as the first time correction amount E4, the time correction amount obtained by subtracting the second time correction amounts E2 and E3 calculated for the section SC from the overall time correction amounts E2, E3, and E4 calculated based on the estimated change in the oscillation frequency of the crystal resonator 10 for the section SC. When the first correction unit 53a performs time correction using the first time correction amount with a delay, to prevent a correction amount already performed by the second correction unit 53b from being double-inclusive, as described above, the first correction unit 53a calculates, as the first time correction amount E4, the time correction amount obtained by subtracting the second time correction amounts E2 and E3 from the overall time correction amounts E2, E3, and E4, thereby separating the correction amounts of the first correction unit 53a and the second correction unit 53b. Here, for example, when the first correction unit 53a performs a calculation to subtract the second time correction amounts E2 and E3 from the overall time correction amounts E2, E3, and E4, the first correction unit 53a may use the second time correction amounts E2 and E3 stored in the memory unit 40.

[0080] The first correction unit 53a corrects the clock signal and performs time correction by outputting a first time correction signal corresponding to the first time correction amount E4 to the clock output unit 20. That is, the electronic watch 100 according to the first modified embodiment performs instantaneous time correction using the second correction unit 53b, and then performs more accurate time correction using the first correction unit 53a.

[0081] In other words, in the electronic timepiece 100 according to the first modification of the embodiment, the deviation of the first stored value from the reference frequency B1 is detected upon temperature measurement, the second time correction amount is calculated, and the second correction unit 53b immediately corrects the time error using the second time correction amount. On the other hand, the first correction unit 53a does not immediately correct the first time correction amount determined from the estimated frequency for the first stored value in section SC, but rather delays the correction and incorporates it into the correction amount used to correct the subsequent time error. As a result, in the electronic timepiece 100 according to the modification, the second correction unit 53b corrects the time based on the deviation of the first stored value each time a temperature measurement is performed, maintaining a certain degree of time accuracy in response to temperature changes. Furthermore, the first correction unit 53a delays the time correction based on the detailed deviation amount associated with temperature changes, making it possible to maintain high time accuracy over fixed periods, such as monthly or annual differences, while maintaining real-time time accuracy.

[0082] In the above, it has been explained that the second correction unit 53b performs time correction regarding the deviation amount of the first memory value at the timing of temperature measurement, but if the period of time correction is more than twice as long as the period of temperature measurement, the second correction unit 53b may perform time correction by combining correction amounts (second time correction amounts E2 and E3) corresponding to the deviation amounts of multiple first memory values ​​at the timing of time correction.

[0083] Furthermore, in the electronic timepiece 100 according to the first modification of the embodiment, the second correction unit 53b may store in the storage unit 40 second fractional correction amounts E2 and E3 that are smaller than the minimum resolution of the clock output unit 20. In this case, the first correction unit 53a calculates an approximate second time correction amount by subtracting the second fractional correction amount for the interval SC from the second time correction amounts E2 and E3 calculated for that interval SC, and calculates the first time correction amount E4 by subtracting the approximate second time correction amount from the overall time correction amounts E2, E3, and E4 for the interval SC. With this configuration, the second fractional correction amounts that were not reflected in the time correction by the second correction unit 53b can be reflected all at once in the time correction by the first correction unit 53a.

[0084] As described above, in the electronic watch 100 relating to the first variant of the embodiment, the control unit 50 calculates, based on the first memory value for each measurement, a second time correction amount, which is a correction amount for correcting the time error caused by the deviation of the oscillation frequency of the vibrator 200 from the reference frequency between the measurement of the measured temperature corresponding to the first memory value and the next or subsequent specified measurement, and further has a second correction unit 53b that performs time correction based on the second time correction amount instantly for each measurement, and the first correction unit 53a calculates, as the first time correction amount E4, the time correction amount obtained by subtracting the second time correction amounts E2 and E3 calculated in the section SC from the overall time correction amounts E2, E3, and E4 calculated based on the change in the estimated oscillation frequency of the vibrator 200 in the section SC.

[0085] In the electronic timepiece 100 according to the first modification of the embodiment, the second correction unit 53b corrects the time every time the temperature measurement unit 30a measures the temperature, thereby improving the real-time nature of the time correction. Furthermore, after the correction by the second correction unit 53b, the first correction unit 53a corrects the time using the first time correction amount E4, which is calculated based on changes in the oscillation frequency of the vibrator 200 and then subtracts the second time correction amounts E2 and E3 from the time correction amount, thereby improving the accuracy of the time.

[0086] Furthermore, in the electronic clock 100 relating to the first variant of the embodiment, the first correction unit 53a performs time correction by outputting a first time correction signal corresponding to the first time correction amount E4 to the clock output unit 20 and correcting the clock signal, the second correction unit 53b performs time correction by outputting a second time correction signal corresponding to the second time correction amounts E2 and E3 to the clock output unit 20 and correcting the clock signal, and stores a second fractional correction amount that is smaller than the minimum resolution of the clock output unit 20 for the second time correction amounts E2 and E3 in the memory unit 40, the first correction unit 53a subtracts the second fractional correction amount for the section SC from the second time correction amounts E2 and E3 calculated for the section SC to obtain an approximate second time correction amount, and calculates the time correction amount obtained by subtracting the approximate second time correction amount from the overall time correction amounts E2, E3, and E4 for the section SC as the first time correction amount E4.

[0087] As described above, the electronic timepiece 100 according to the first modified embodiment can reflect, in a lump sum, the second fractional correction amount that is smaller than the minimum resolution of the clock output unit 20 and that was not reflected in the time correction by the second correction unit 53b when the first correction unit 53a subsequently corrects the time. With this configuration, the electronic timepiece 100 according to the first modified embodiment can reflect, in the time correction, the second fractional correction amount that is smaller than the minimum resolution of the clock output unit 20, further improving the accuracy of the time.

[0088] [Second Modification of the Embodiment] A second modified example of the embodiment will now be described. Fig. 7 is a conceptual diagram showing an electronic timepiece according to a first modified example of the embodiment.

[0089] The second modified example of the embodiment differs from the above embodiment in that the electronic timepiece 100 further includes a voltage measurement unit 30b, as shown in Figure 7. The rest of the configuration is the same as the above embodiment.

[0090] The voltage measurement unit 30b is a component that intermittently measures the voltage of a power supply (not shown) of the oscillation circuit using the crystal unit 10 in the electronic timepiece 100 and outputs a signal corresponding to the measured voltage to the control unit 50 for each measurement. The control unit 50 stores a second stored value corresponding to the measured voltage in the storage unit 40 based on the output from the voltage measurement unit 30b. The control unit 50 stores the second stored value as time-series data, associating the time of measurement by the temperature measurement unit 30a with the time of measurement by the voltage measurement unit 30b. Through this process, the first stored value and the second stored value are stored as time-series data in the storage unit 40, associated with each other by the measurement time. Here, the first stored value is a temperature value, and the second stored value is a voltage value. The first stored value may be the oscillation frequency value of the crystal unit 10 at the measurement temperature corresponding to the first stored value, and the second stored value may be the oscillation frequency value of the crystal unit 10 to which the measurement voltage corresponding to the second stored value is applied.

[0091] The oscillation frequency of the crystal resonator 10 has the characteristic that the oscillation frequency changes depending on the increase or decrease in the voltage applied to the oscillation circuit. A table (three-dimensional graph data) of the temperature characteristics of the oscillation frequency according to the power supply voltage of the oscillation circuit is prepared, and the oscillation frequency is estimated and corrected from the table according to the measured temperature and the power supply voltage of the oscillation circuit stored as the first and second stored values.

[0092] In a second modified example of the embodiment, the estimation unit 52 estimates a change in the oscillation frequency of the crystal resonator 10 in the section SC based on the time series data of the first stored value and the time series data of the second stored value. For example, the storage unit 40 stores three-dimensional graph data of frequency characteristics relating to temperature changes and power supply voltage changes of the oscillation circuit, and the estimation unit 52 uses the three-dimensional graph data to calculate the oscillation frequency when a voltage of the voltage value measured by the voltage measurement unit 30b is applied to the crystal resonator 10 at the temperature measured by the temperature measurement unit 30a, thereby estimating a change in the oscillation frequency of the crystal resonator 10 in the section SC.

[0093] The first correction unit 53a calculates a first time correction amount, which is a correction amount for correcting the time error caused by the change in the oscillation frequency of the crystal oscillator 10 in the section SC, based on the change in the oscillation frequency of the crystal oscillator 10 estimated in the section SC, and corrects the time error caused by the change in the oscillation frequency of the crystal oscillator 10 by outputting a first time correction signal corresponding to the first time correction amount to the clock output unit 20.

[0094] The estimation unit 52 may calculate an estimated value of the oscillation frequency corresponding to the first stored value and the second stored value within a predetermined interval of the time-series data of the first stored value and the second stored value by calculating the following formula (2), and estimate a change in the oscillation frequency of the crystal resonator 10 within that interval. Estimated oscillation frequency = f(temperature, voltage) (2) That is, the change in the oscillation frequency of the crystal unit 10 may be estimated by calculating a function with the temperature value of the crystal unit 10 and the voltage value of the power supply of the oscillation circuit as variables.

[0095] Alternatively, the estimation unit 52 may calculate the estimated value of the oscillation frequency corresponding to the first stored value and the second stored value within a predetermined interval of the time-series data of the first stored value and the second stored value by calculating the following equation (3) instead of the equation (2), and estimate the change in the oscillation frequency of the crystal resonator 10 within the predetermined interval. Estimated oscillation frequency = f1 (temperature value) + f2 (voltage value) (3) In equation (3), it is assumed that there is no dependency between the temperature value of the crystal unit 10 and the voltage value of the voltage applied to the crystal unit 10, and an estimated value of the oscillation frequency of the crystal unit 10 at the temperature corresponding to the first stored value and an estimated value of the oscillation frequency of the crystal unit 10 to which a voltage corresponding to the second stored value is applied are calculated independently, and the calculated estimated values ​​are added together to calculate an estimated value of the oscillation frequency of the crystal unit 10 that reflects the effects of temperature and the voltage of the power supply of the oscillation circuit.

[0096] As described above, the electronic watch 100 according to the second variant of the embodiment further includes a voltage measurement unit 30b that intermittently measures the voltage of the power supply of the oscillator circuit and outputs an output according to the measured voltage for each measurement. The memory unit 40 stores the measured voltage and the corresponding second memory value based on the output from the voltage measurement unit 30b, associating them with time series data so that the time of measurement by the temperature measurement unit 30a corresponds to the time of measurement by the voltage measurement unit 30b. The estimation unit 52 estimates the change in the oscillation frequency of the vibrator 200 in the section SC based on the time series data of the first memory value and the time series data of the second memory value.

[0097] The electronic watch 100 according to the second variant of the embodiment estimates the change in the oscillation frequency of the quartz oscillator due to the change in the power supply voltage of the oscillator circuit and the change in the temperature of the oscillator 200 using the estimation unit 52, and calculates the first time correction amount based on the estimated change in the oscillation frequency of the oscillator 200 using the first correction unit 53a, thereby enabling more precise time correction.

[0098] The contents disclosed in the above-described embodiment and each modification can be implemented in appropriate combination. [Explanation of symbols]

[0099] 10: Crystal oscillator 20: Clock output section 30a: temperature measurement unit, 30b: voltage measurement unit 40: Storage part 50: control unit, 51: timing unit, 52: estimation unit, 53a: first correction unit 53b: second correction unit, 54: section designation unit 100: Electronic clock 200: Vibrator

Claims

1. A vibrator and a clock output unit that generates a clock signal based on the oscillation frequency of the oscillator; a temperature measurement unit that intermittently measures the ambient temperature of the vibrator and outputs an output corresponding to the measured temperature for each measurement; a storage unit configured to store, as time-series data, first stored values ​​corresponding to the measured temperatures based on an output from the temperature measurement unit; A control unit; Equipped with The control unit a timekeeping unit that keeps time based on the clock signal; an estimation unit that estimates a change in the oscillation frequency of the vibrator or a change in the ambient temperature of the vibrator in a section between at least two consecutive first stored values ​​in the time series data of the first stored values ​​stored in the storage unit, based on the time series data of the first stored values; a first correction unit that calculates a first time correction amount, which is a correction amount for correcting a time error that occurs in the interval, based on either the estimated oscillation frequency of the oscillator in the interval or a change in the ambient temperature of the oscillator, and performs time correction based on the first time correction amount; An electronic watch comprising:

2. The first correction unit outputting a first time correction signal corresponding to the first time correction amount to the clock output unit to correct the clock signal, thereby correcting the time; storing a first fractional correction amount, which is smaller than the minimum resolution of the clock output unit in the first time correction amount, in the storage unit; The first fractional correction amount is included in the first time correction amount at the next or subsequent predetermined time correction.

2. The electronic watch according to claim 1, wherein the electronic watch is a clock.

3. The control unit a second correction unit that calculates, based on the first stored value for each measurement, a second time correction amount that is a correction amount for correcting a time error caused by a deviation of the oscillation frequency of the oscillator from a reference frequency between the measurement of the measured temperature corresponding to the first stored value and a next or subsequent measurement, and performs time correction based on the second time correction amount for each measurement; The first correction unit calculating, as the first time correction amount, a time correction amount obtained by subtracting the second time correction amount calculated for the interval from an overall time correction amount calculated based on the change in the oscillation frequency of the oscillator estimated for the interval; 3. The electronic timepiece according to claim 1 or 2.

4. The first correction unit outputting a first time correction signal corresponding to the first time correction amount to the clock output unit to correct the clock signal, thereby correcting the time; The second correction unit outputting a second time correction signal corresponding to the second time correction amount to the clock output unit to correct the clock signal, thereby correcting the time; storing a second fractional correction amount, which is smaller than the minimum resolution of the clock output unit in the second time correction amount, in the storage unit; The first correction unit an approximate second time correction amount is calculated by subtracting the second fractional correction amount for the interval from the second time correction amount calculated for the interval, and a time correction amount is calculated by subtracting the approximate second time correction amount from the total time correction amount for the interval as the first time correction amount; 4. The electronic watch according to claim 3.

5. Further comprising a voltage measurement unit that intermittently measures a voltage of a power supply of an oscillation circuit using the vibrator and outputs an output corresponding to the measured voltage for each measurement, The storage unit based on an output from the voltage measurement unit, storing a second stored value corresponding to the measured voltage as time-series data in such a manner that a time of measurement by the temperature measurement unit corresponds to a time of measurement by the voltage measurement unit; The estimation unit estimating a change in the oscillation frequency of the vibrator in the section based on the time series data of the first stored value and the time series data of the second stored value; 3. The electronic timepiece according to claim 1 or 2.

6. The first correction unit outputting a first time correction signal corresponding to the first time correction amount to the clock output unit to correct the clock signal, thereby correcting the time; a temperature resolution correction value that is smaller than a minimum resolution of the temperature measurement unit, the temperature resolution correction value being a difference between the first stored value and a value estimated based on time-series data of the first stored value, being stored in the storage unit; At the next or subsequent predetermined time correction, the temperature resolution correction value is included in the first time correction amount at the predetermined time correction.

3. The electronic timepiece according to claim 1 or 2.

7. The first correction unit When the time correction is performed by incorporating the first fractional correction amount equal to or greater than the minimum resolution of the clock output unit into the first time correction amount, a residual value of the first time correction amount that was not reflected in the time correction is stored in the storage unit, and at a specified time correction subsequent to the time correction, the residual value of the first fractional correction amount is included in the first time correction amount at the specified time correction.

3. The electronic timepiece according to claim 2.

8. The first correction unit When the time correction is performed by including the temperature resolution correction value equal to or greater than the minimum resolution of the temperature measurement unit in the first time correction amount, a residual value of the temperature resolution correction value that was not reflected in the time correction is stored in the storage unit, and at a specified time correction subsequent to the time correction, the residual value of the temperature resolution correction value is included in the first time correction amount at the specified time correction.

7. The electronic watch according to claim 6, wherein the electronic watch is a clock.

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