The present application is based on, and claims priority from, JP Application Serial Number 2018-106871, filed Jun. 4, 2018, and JP Application Serial Number 2019-008520, filed Jan. 22, 2019, the disclosure of which are hereby incorporated by reference herein in their entireties.

BACKGROUND

1. Technical Field

The present invention relates to an electronically controlled mechanical timepiece, a control method of an electronically controlled mechanical timepiece, and an electronic timepiece.

This application claims priority based upon Japanese Patent Application 2018-106871, filed on Jun. 4, 2018, and Japanese Patent Application 2019-008520, filed on Jan. 22, 2019, the entire contents of which are incorporated by reference herein.

2. Related Art

Electronically controlled mechanical timepieces configured to precisely drive hands affixed to a wheel train and accurately display the time by charging a power circuit with electrical energy generated by driving an electrical generator by means of mechanical energy produced by a spring unwinding, and controlling rotation of the rotor of the generator by operating a brake control circuit by means of the electrical energy, are known from the literature. See, for example, JP-A-2000-346962.

In an electronically controlled mechanical timepiece, the torque (mechanical energy) applied by the spring to the generator is set so that the hands turn at a faster rate than a reference speed, and regulate the rotational speed by means of a brake control device braking the generator.

More specifically, a reference signal based on the oscillation signal output from a crystal oscillator is compared with a rotation detection signal corresponding to the rotational period of the rotor of the generator, and the amount of braking to apply to the generator is set to regulate the generator. An electronically controlled mechanical timepiece can therefore maintain time accuracy corresponding to the precision of the reference signal.

Because a crystal oscillator has a specific thermal characteristic, if the temperature of the operating environment of the electronically controlled mechanical timepiece varies greatly from the normal temperature (such as 25° C.) used as the reference temperature of the thermal characteristic, the oscillation frequency of the crystal oscillator changes, the frequency of the reference signal changes, and the accuracy of the time kept by the electronically controlled mechanical timepiece decreases. This can conceivably be compensated for by providing a temperature compensation function (temperature compensator) enabling temperature compensation of the crystal oscillator.

However, providing a temperature compensator increases current consumption. As the spring unwinds in an electronically controlled mechanical timepiece, the torque applied to the generator decreases and the generated energy output of the generator drops. As a result, when the current consumption of the temperature compensator is high, the energy balance decreases when the mechanical energy applied to the generator by the spring is low, output voltage sufficient to drive the temperature compensator and the brake control device cannot be produced, and accurate regulation control cannot be maintained. More specifically, the autonomy of accurate operation of the electronically controlled mechanical timepiece becomes shorter.

A temperature compensator (temperature compensation function) that can be driven with low current consumption and low voltage in an electronically controlled mechanical timepiece so that the brake control device and temperature compensator can continue operating even when the torque applied to the generator is low and the generated power output is low therefore needed.

A temperature compensator (temperature compensation function) that can be driven with low current consumption and low voltage is also desirable in a typical electronic timepiece using a crystal oscillator.

SUMMARY

An object of the present invention is to provide an electronically controlled mechanical timepiece having a temperature compensator that can be driven with low current consumption and low voltage, a control method of an electronically controlled mechanical timepiece, and an electronic timepiece.

An electronically controlled mechanical timepiece according to an aspect of the invention includes: a mechanical energy source; a generator including a rotor driven by the mechanical energy source; an energy transfer mechanism configured to transfer torque from the mechanical energy source to the rotor; a time display device connected to the energy transfer mechanism and configured to display time; a rotation controller that controls rotation of the rotor; a crystal oscillator; and a power supply circuit that stores electrical energy generated by the generator.

The rotation controller includes an oscillation circuit that causes the crystal oscillator to oscillate, a frequency divider that frequency divides an oscillation signal output from the oscillation circuit and outputs a reference signal, a temperature compensator configured to compensate for variation in the reference signal due to temperature, a rotation detection circuit configured to measure the rotational frequency of the rotor, and a brake control circuit configured to control braking the rotor according to a difference between the rotational frequency of the rotor and the frequency of the reference signal.

The temperature compensator includes a frequency adjustment control circuit configured to control the oscillation circuit, a theoretical regulation circuit configured to control the frequency divider, a temperature detector configured to measure temperature, an arithmetic circuit, temperature compensation table storage in which temperature compensation data common to electronically controlled mechanical timepieces is stored, device-difference compensation data storage in which device-difference compensation data for the electronically controlled mechanical timepiece is stored, a first switch configured to control connection and disconnection of the temperature compensation table storage to the power supply circuit, and a second switch configured to control connection and disconnection of the device-difference compensation data storage to the power supply circuit.

The arithmetic circuit calculates a compensation amount based on a measured temperature detected by the temperature detector, the temperature compensation data, and the device-difference compensation data, and outputs to the frequency adjustment control circuit and the theoretical regulation circuit. The first switch is controlled to a connect state during a first power supply connection period including a temperature compensation data read period when at least the temperature compensation data is read from the temperature compensation table storage, and to a disconnect state when not in the first power supply connection period. The second switch controlled to a connect state during a second power supply connection period including a device-difference compensation data read period when at least the device-difference compensation data is read from the device-difference compensation data storage, and to a disconnect state when not in the second power supply connection period.

An electronically controlled mechanical timepiece according to this aspect of the invention has a generator that is driven by a mechanical energy source such as a spring, and by regulating the rotational speed of the rotor of the generator, accurately drives the hands of the time display, and includes an arithmetic circuit that calculates compensation based on the temperature measured by the temperature detector; a frequency adjustment control circuit that adjusts the frequency of the oscillation signal by controlling additional capacitance of the oscillation circuit based on the compensation; and a theoretical regulation circuit that controls the frequency divider based on the compensation and changes the timing of signal change in the reference signal output from the frequency divider.

As a result, by making coarse adjustments with the theoretical regulation circuit, and fine adjustments with the frequency adjustment control circuit, compensation for the thermal characteristics of the crystal oscillator, for example, is possible, the frequency precision of the reference signal can be improved, and time accuracy can be improved even when the temperature of the electronically controlled mechanical timepiece changes according to the operating environment.

Because temperature compensation table storage storing data common to electronically controlled mechanical timepieces, and device-difference compensation data storage storing compensation data for individual differences between electronically controlled mechanical timepieces, are provided, compensation data can be efficiently stored, and the footprint of the IC can be reduced. More specifically, because rewriting data to the temperature compensation table storage is not necessary, the temperature compensation table storage can be configured using mask ROM enabling reducing the circuit scale, and rewritable nonvolatile memory can be used to store only the device-difference compensation data, the space occupied in the IC can be reduced. Reducing the size of the device-difference compensation data storage also enables reducing operating current and leakage current when not operating.

Furthermore, because there are a first switch and a second switch between the temperature compensation table storage and device-difference compensation data storage and the power supply circuit, the temperature compensation table storage and device-difference compensation data storage can be connected to the power supply circuit only when reading compensation data, can be disconnected from the power supply circuit when not reading, and leakage current when not reading from storage can therefore be reduced.

More particularly, because leakage current increases when the internal temperature of the electronically controlled mechanical timepiece rises, the effect of reducing leakage current can be increased by isolating the storage from the power supply circuit. Because the electronically controlled mechanical timepiece charges the generated electrical energy to a capacitor or other power supply circuit and drives the IC by voltage from the power supply circuit, if the current consumption of the IC increases, the discharge from the power supply circuit increases, and the voltage of the power supply circuit decreases. If this voltage goes below the voltage at which the IC stops operating (IC stop-operating voltage), the IC will stop and regulation cannot be controlled. Therefore, if current consumption by the IC is low, voltage sufficient to drive the IC can still be acquired even when the mechanical energy applied from the spring is low, and the autonomy of the electronically controlled mechanical timepiece can be improved.

Furthermore, by combining a theoretical regulation circuit and a frequency adjustment control circuit, a temperature compensator capable of fine frequency control with low current consumption can be provided. More specifically, a theoretical regulation circuit can suppress increasing current consumption, but does not enable fine adjustment of the reference signal. In addition, the frequency adjustment control circuit can finely adjust the reference signal, but the additional capacitance must be increased greatly to increase the adjustment range, and current consumption increases by increased charging and discharging of the additional capacitance.

By combining a theoretical regulation circuit and frequency adjustment control circuit with these characteristics, the invention enables precise adjustment of the reference signal while also reducing current consumption.

In an electronically controlled mechanical timepiece according to another aspect of the invention, the rotation controller includes a constant voltage circuit; the oscillation circuit, frequency divider, brake control circuit, temperature compensator, frequency adjustment control circuit, arithmetic circuit, and temperature detector are driven by a constant voltage output from the constant voltage circuit; and the temperature compensation table storage and device-difference compensation data storage are driven by a power source other than the constant voltage circuit.

Because the constant voltage circuit can output a fixed voltage even if the voltage (generated voltage) of the power supply circuit charged by the generator fluctuates, if the oscillation circuit and temperature detector are driven by a constant voltage, increasing the current consumption can be prevented even if the generated voltage increases. In addition, by driving the oscillation circuit and temperature detector at a fixed voltage, fluctuation due to the output signal voltage can be reduced. As a result, low current consumption and high precision can be achieved in an electronically controlled mechanical timepiece that requires low current consumption.

Furthermore, because current consumption increases during operation if nonvolatile memory, for example, is used for the temperature compensation table storage and device-difference compensation data storage, if the storage is driven by a constant voltage circuit, the output voltage of the constant voltage circuit may fluctuate. Voltage fluctuation in the constant voltage circuit can cause variation in the frequency of the output signal of the oscillation circuit and operation of the oscillation circuit to stop. As a result, the temperature compensation table storage and device-difference compensation data storage are driven by a power supply other than the constant voltage circuit that drives the oscillation circuit and temperature detector, such as by the voltage at the ends of a power supply circuit (capacitor). Therefore, even if the voltage of the power supply circuit drops due to the current consumption of temperature compensation table storage and device-difference compensation data storage operation, the effect on the output of the constant voltage circuit is reduced, and variation in the frequency of the output signals from the oscillation and temperature detector, as well as operation of the oscillation circuit stopping, can be prevented.

In addition, because the output voltage of the constant voltage circuit can be set low within the range not below the stop-operating voltage of the oscillation circuit and temperature detector, the IC can be driven with low current consumption. Generated voltage sufficient to drive the IC can therefore be sustained even when the mechanical energy supplied from the spring is low, and autonomy can be increased.

In an electronically controlled mechanical timepiece according to another aspect of the invention, the temperature measurement period when the temperature detector operates, the temperature compensation data read period, and the device-difference compensation data read period are set to different times.

Because the electrical energy generated in an electronically controlled mechanical timepiece is relatively low, a capacitor with lower internal resistance than a storage battery is preferably used in the power supply circuit. Because a capacitor has lower capacitance than a storage battery, the voltage drop from a current load increases. As a result, if a temperature detector requiring a relatively large operating current, the temperature compensation table storage, and the device-difference compensation data storage in the circuits used in the electronically controlled mechanical timepiece operate at the same time, the current load rises, the voltage of the power supply circuit (capacitor) will drop and may go below the voltage at which IC operation stops. If the IC stops operating, movement of the hands cannot be controlled, and the accurate time cannot be displayed.

Therefore, by setting the temperature measurement period when the temperature detector operates, the temperature compensation data read period, and the device-difference compensation data read period to different times, and controlling operation so these periods do not overlap, the current load can be dispersed, and a voltage drop in the power supply circuit going below the stop-operating voltage of the IC can be prevented. Therefore, the generated voltage dropping below the voltage at which IC operation stops is prevented, accurate regulation can be maintained, and autonomy can be improved even when the mechanical energy applied from the spring is low, and the voltage generated at the ends of the power supply circuit is low.

In an electronically controlled mechanical timepiece according to another aspect of the invention, the rotation controller is configured by an IC manufactured in an SOI process; and the device-difference compensation data storage is configured by FAMOS.

Data stored in the device-difference compensation data storage is data for adjusting individual differences in the characteristics of the oscillation circuit and temperature detector to the ideal characteristics, and this data must be written during the mass production processes of an electronically controlled mechanical timepiece. The device-difference compensation data storage is therefore configured with nonvolatile memory in which the written data is not erased when there is no voltage from the power supply circuit. The nonvolatile memory is normally nonvolatile memory that can be written multiple times, such as EEPROM. However, a high voltage is required to write nonvolatile memory such as EEPROM. In addition, an IC manufactured in a SOI (Silicon On Insulator) process has a low breakdown voltage, and therefore cannot include nonvolatile memory that requires a high voltage to write.

As a result, FAMOS (Floating gate Avalanche injection Metal Oxide Semiconductor) memory is used as the nonvolatile memory for the device-difference compensation data storage. Because FAMOS memory can be written with a low voltage, exceeding the breakdown voltage and resulting device failure can be prevented even in a SOI process IC having a low breakdown voltage. A rotation controller (IC) manufactured in an SOI process and having a temperature compensator, low leakage current, and drivable by a low voltage can therefore be provided.

In an electronically controlled mechanical timepiece according to another aspect of the invention, the temperature detector is configured by a RC oscillator circuit driven by a constant current.

If a RC oscillator circuit driven by a constant current is used as the temperature detector, the constant current and resistance vary with the environmental temperature, a signal of a frequency corresponding to the environmental temperature is output from the RC oscillator circuit, and the temperature can be detected from the frequency. Furthermore, because the drive current of the temperature detector is determined by the constant current, the current can be easily controlled by the design, and low current consumption can be easily achieved.

Of current consumption is low, generated voltage sufficient to drive the IC can be sustained even when the mechanical energy supplied from the spring is low, and autonomy can be increased.

Another aspect of the invention is a control method of an electronically controlled mechanical timepiece including a mechanical energy source; a generator including a rotor driven by the mechanical energy source; an energy transfer mechanism configured to transfer torque from the mechanical energy source to the rotor; a time display device connected to the energy transfer mechanism and configured to display time; a rotation controller that controls rotation of the rotor; a crystal oscillator; and a power supply circuit that stores electrical energy generated by the generator; the rotation controller including an oscillation circuit that causes the crystal oscillator to oscillate, a frequency divider that frequency divides an oscillation signal output from the oscillation circuit and outputs a reference signal, a temperature compensator configured to compensate for variation in the reference signal due to temperature, a rotation detection circuit configured to measure the rotational frequency of the rotor, and a brake control circuit configured to control braking the rotor according to a difference between the rotational frequency of the rotor and the frequency of the reference signal; the temperature compensator including a temperature detector configured to measure temperature, temperature compensation table storage in which temperature compensation data common to electronically controlled mechanical timepieces is stored, device-difference compensation data storage in which device-difference compensation data specific to an electronically controlled mechanical timepiece is stored, a first switch configured to control connection and disconnection of the temperature compensation table storage to the power supply circuit, and a second switch configured to control connection and disconnection of the device-difference compensation data storage to the power supply circuit; and the control method including a step of operating the temperature detector to measure temperature; a step of setting the first switch to a connect state, reading the temperature compensation data from the temperature compensation table storage, and setting the first switch to a disconnect state; a step of setting the second switch to a connect state, reading the device-difference compensation data from the device-difference compensation data storage, and setting the second switch to a disconnect state; a step of calculating a compensation amount based on a measured temperature, the temperature compensation data, and the device-difference compensation data; a step of controlling the oscillation circuit according to the compensation; and a step of controlling the frequency divider according to the compensation.

This control method has the same effect as the electronically controlled mechanical timepiece described above.

An electronic timepiece according to another aspect of the invention includes a time display device configured to display time; a crystal oscillator; a power supply circuit; an oscillation circuit that causes the crystal oscillator to oscillate; a frequency divider that frequency divides an oscillation signal output from the oscillation circuit and outputs a reference signal; and a temperature compensator that compensates for variation in the reference signal due to temperature. The temperature compensator includes a frequency adjustment control circuit configured to control the oscillation circuit, a theoretical regulation circuit configured to control the frequency divider, a temperature detector configured to measure temperature, an arithmetic circuit, temperature compensation table storage in which temperature compensation data common to another electronic timepiece is stored, device-difference compensation data storage in which device-difference compensation data based on a characteristic of the crystal oscillator is stored, a first switch configured to control connection and disconnection of the temperature compensation table storage to the power supply circuit, and a second switch configured to control connection and disconnection of the device-difference compensation data storage to the power supply circuit. The arithmetic circuit calculates a compensation amount based on a measured temperature detected by the temperature detector, the temperature compensation data, and the device-difference compensation data, and outputs to the frequency adjustment control circuit and the theoretical regulation circuit, The first switch is controlled to a connect state during a first power supply connection period including a temperature compensation data read period when at least the temperature compensation data is read from the temperature compensation table storage, and to a disconnect state when not in the first power supply connection period. The second switch is controlled to a connect state during a second power supply connection period including a device-difference compensation data read period when at least the device-difference compensation data is read from the device-difference compensation data storage, and to a disconnect state when not in the second power supply connection period.

An electronic timepiece according to this aspect of the invention has a generator that is driven by a mechanical energy source such as a spring, and by regulating the rotational speed of the rotor of the generator, accurately drives the hands of the time display, and includes an arithmetic circuit that calculates compensation based on the temperature measured by the temperature detector; a frequency adjustment control circuit that adjusts the frequency of the oscillation signal by controlling additional capacitance of the oscillation circuit based on the compensation; and a theoretical regulation circuit that controls the frequency divider based on the compensation and changes the timing of signal change in the reference signal output from the frequency divider.

As a result, by making coarse adjustments with the theoretical regulation circuit, and fine adjustments with the frequency adjustment control circuit, compensation for the thermal characteristics of the crystal oscillator, for example, is possible, the frequency precision of the reference signal can be improved, and time accuracy can be improved even when the temperature of the electronic timepiece changes according to the operating environment.

Because temperature compensation table storage storing data common to electronic timepieces, and device-difference compensation data storage storing compensation data for individual differences between electronic timepieces, are provided, compensation data can be efficiently stored, and the footprint of the IC can be reduced. More specifically, because rewriting data to the temperature compensation table storage is not necessary, the temperature compensation table storage can be configured using mask ROM enabling reducing the circuit scale, and rewritable nonvolatile memory can be used to store only the device-difference compensation data, the space occupied in the IC can be reduced. Reducing the size of the device-difference compensation data storage also enables reducing operating current and leakage current when not operating.

Furthermore, because there are a first switch and a second switch between the temperature compensation table storage and device-difference compensation data storage and the power supply circuit, the temperature compensation table storage and device-difference compensation data storage can be connected to the power supply circuit only when reading compensation data, can be disconnected from the power supply circuit when not reading, and leakage current when not reading from storage can therefore be reduced.

More particularly, because leakage current increases when the internal temperature of the electronic timepiece rises, the effect of reducing leakage current can be increased by isolating the storage from the power supply circuit. Because the electronic timepiece drives the IC by voltage from the power supply circuit, if the current consumption of the IC increases, the discharge from the power supply circuit increases, and the voltage drop of the power supply circuit is faster than when the current consumption of the IC is low. If this voltage goes below the voltage at which the IC stops operating, the IC will stop and regulation cannot be controlled. In other words, the autonomy of the electronic timepiece becomes shorter. Therefore, because discharge from the power supply circuit decreases when current consumption by the IC is low, the voltage drop of the power supply circuit is also delayed, voltage sufficient to drive the IC can be maintained for a longer time, and the autonomy of the electronically controlled mechanical timepiece can be improved.

Furthermore, by combining a theoretical regulation circuit and a frequency adjustment control circuit, a temperature compensator capable of fine frequency control with low current consumption can be provided. More specifically, a theoretical regulation circuit can suppress increasing current consumption, but does not enable fine adjustment of the reference signal. In addition, the frequency adjustment control circuit can finely adjust the reference signal, but the additional capacitance must be increased greatly to increase the adjustment range, and current consumption increases by increased charging and discharging of the additional capacitance.

By combining a theoretical regulation circuit and frequency adjustment control circuit with these characteristics, the invention enables precise adjustment of the reference signal while also reducing current consumption.

An electronic timepiece according to another aspect of the invention preferably also has a constant voltage circuit that drives at least the oscillation circuit by a constant voltage; and the temperature compensation table storage and device-difference compensation data storage are driven by a power source other than the constant voltage circuit.

Because a constant voltage circuit outputs a fixed voltage even when the voltage of a power supply circuit configured by a primary battery or storage battery fluctuates, if at least the oscillation circuit is driven by a constant voltage, an increase in current consumption can be prevented even if the voltage of the power supply circuit increases. In addition, by driving the oscillation circuit by a constant voltage, fluctuation due to the voltage of the output signal can be reduced. As a result, low current consumption and high precision can be achieved in an electronic timepiece.

Furthermore, because current consumption increases during operation if nonvolatile memory, for example, is used for the temperature compensation table storage and device-difference compensation data storage, if the storage is driven by a constant voltage circuit, the output voltage of the constant voltage circuit may fluctuate. Voltage fluctuation in the constant voltage circuit can cause variation in the frequency of the output signal of the oscillation circuit and operation of the oscillation circuit to stop. As a result, the temperature compensation table storage and device-difference compensation data storage are driven by a power supply other than the constant voltage circuit that drives the oscillation circuit, such as by the voltage at the ends of a power supply circuit (primary battery or storage battery). Therefore, even if the voltage of the power supply circuit drops due to the current consumption of temperature compensation table storage and device-difference compensation data storage operation, the effect on the output of the constant voltage circuit is reduced, and variation in the frequency of the output signals from the oscillation detector, as well as operation of the oscillation circuit stopping, can be prevented.

In addition, because the output voltage of the constant voltage circuit can be set low within the range not below the stop-operating voltage of the oscillation circuit and temperature detector, the IC can be driven with low current consumption. Generated voltage sufficient to drive the IC can therefore be sustained even when the mechanical energy supplied from the spring is low, and autonomy can be increased.

Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.

