Statistically driven rate stabilizer

Abstract

An object of the present invention is to provide a timepiece rate stabilizer that uses an external reference but does not directly inject mechanical vibrations into the balance, and that can stabilize the rate over a long period of time with extremely low power consumption. [Solution] We provide a rate stabilizer for mechanical watches that is based on a statistical driving method with constant pulse width and amplitude and autonomously switches between four modes based on actual current consumption: normal mode using phase shift, ΔΣ1 bit stream mode, low detune frequency hopping mode, and chirp search mode.Without modifying the hairspring at all, we achieve both rate stability and low power consumption while maintaining constant instantaneous energy.

Description

[Technical Field]

[0001] The present invention relates to a timepiece rate stabilizer that stabilizes the long-term rate of the balance of a mechanical timepiece by optimizing energy injection through stochastic modulation. [Background technology]

[0002] In mechanical watches, the natural frequency F0 of the balance wheel fluctuates slightly due to torque fluctuations in the mainspring, temperature, positional differences, external shocks, etc., and long-term rate errors are unavoidable. Conventionally, pulse control methods have been known that inject energy by instantaneously modulating the spring stiffness k or damping c, but these methods have had issues with Q-value degradation and increased power consumption due to the need to vary the instantaneous pulse energy.

[0003] Patent document 1 discloses a method for maintaining and adjusting the frequency of a timepiece resonator mechanism near its natural frequency (ω0), which comprises implementing at least one regulator device that acts on the resonator mechanism by a periodic motion to bring about a periodic modulation of the resonant frequency or quality factor or position of the rest point of the resonator mechanism at an adjustment frequency (ωR) that is 0.9 to 1.1 times an integer multiple of the natural frequency (ω0), the integer being between 2 and 10 inclusive. However, this method brings about periodic modulation of at least one of the resonance frequency, quality factor (Q) and stationary point at the adjustment frequency, which is a periodic motion, and does not maintain and adjust the frequency of the timepiece resonator mechanism near its natural frequency (ω0) by detecting the phase of the balance and controlling the oscillation of the adjustment frequency according to the phase difference with the reference oscillation.

[0004] Patent Document 2 describes a technology relating to a timepiece movement in which a balance oscillator with a piezoelectric spring is excited by electronic control and maintains the oscillation. The voltage applied to the piezoelectric spring is controlled to prevent the mechanical escapement from being driven, allowing the escapement to function as a counter. This reduces the mechanical energy consumption from the barrel and significantly increases the power reserve. Furthermore, electronic control allows for stable control of amplitude and frequency, improving the accuracy of the watch. This method also allows for frequency locking in conjunction with a quartz oscillator, but it involves replacing the "hair spring" with a "piezoelectric spring," which is a material modification characteristic of mechanical watches.

[0005] Patent Document 3 describes a method for achieving fine frequency adjustment in a timepiece's resonance mechanism (particularly a spring-type balance wheel) without disassembly. A femtosecond laser induces an irreversible micro-expansion inside a glass actuator, adjusting the position of the inertial mass with nano-precision to control the vibration frequency. The actuator functions in both the gain and loss directions, can be controlled dynamically or statically, and allows for highly accurate, non-contact adjustment. However, there are problems with this method, such as the need to modify the watch body so that the laser can be irradiated through a transparent window in the watch case (e.g., the glass back cover), and the inability to perform real-time correction to accommodate dynamic changes due to the external environment (temperature, posture). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special table number 2016-536578 [Patent Document 2] Patent Publication No. 2022-185575 [Patent Document 3] Patent Publication No. 2023-97393 Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION An object of the present invention is to provide a statistically driven rate stabilizer that utilizes an external reference but does not directly inject mechanical vibrations into the balance, and that can stabilize rate over a long period of time with extremely low power consumption. [Means for solving the problem]

[0008] In a first aspect of the present invention, there is provided a rate stabilizer for a mechanical timepiece in which the hairspring is not modified, a) at least one detection means selected from an optical reflection sensor or a magnetic sensor for detecting the balance amplitude A and phase φ in a non-contact manner; b) a pulse generator that outputs a pulse external force command having a constant pulse width tp, a constant amplitude Vp, and a constant duty ratio D0 at even half-cycle positions of the balance natural frequency F0; c) an actuator that applies a pulse external force to the balance support in response to the pulse external force command; d) a control circuit including a circuit that operates in a rate correction mode to statistically update a pulse injection probability P(t) (0≦P≦1), which is the probability of injecting the external pulse force, based on the phase difference with an external reference oscillator, or to correct the rate by controlling the average duty ratio D(t) or the drive frequency, and a circuit that sets P(t)=0 and stops excitation when the balance amplitude exceeds an upper limit A_max; Equipped with The rate stabilizer is characterized in that it does not periodically modulate the stiffness, inertia, quality coefficient or position of the rest point of the balance and hairspring. Here, "phase difference" refers to the phase error between the external reference oscillator and the balance. The ON / OFF of pulse external force injection is performed by successively updating the probability P(t) according to the sign and magnitude of the rate error, and a drive waveform is generated by a ΔΣ 1-bit modulator. P(t) is a continuous value between 0 and 1, and the average duty ratio converges proportionally to the rate error, so there is no need to periodically modulate stiffness, inertia, etc.

[0009] Here, the control circuit may operate in a rate correction mode in which the control circuit detects an injection phase of the injection and performs rate correction by changing the pulse injection probability P(t) in real time in proportion to the magnitude of the injection phase. "Injection phase" refers to the phase shift angle that the pulse generator imparts to the even half-cycle timing of 2 F0.

[0010] The control circuit may operate in a rate correction mode in which rate correction is performed using only the average duty ratio D(t) based on a one-bit stream generated by a ΔΣ modulator.

[0011] The control circuit may operate in a rate correction mode in which rate correction is performed while pseudo-randomly hopping among a plurality of frequencies within ±ΔF_ppm centered on a frequency twice the balance natural frequency F0.

[0012] Only when the phase difference exceeds a predetermined threshold value may the antenna operate in a chirp search mode in which a burst of chirp sweeping frequency is injected to attempt re-locking.

[0013] An apparatus is provided which includes a mode management circuit which measures average current consumption I_avg, and when I_avg is less than a first threshold value I1, selects a rate correction mode in which the control circuit performs rate correction using only the average duty ratio D(t) based on a one-bit stream generated by a ΔΣ modulator, when I_avg is greater than or equal to I1 and less than a second threshold value I2, selects a rate correction mode in which the control circuit performs rate correction while pseudo-randomly hopping between multiple frequencies within ±ΔF_ppm centered on twice the balance natural frequency F0, and selects a chirp search mode in which a burst that chirp-sweeps the frequency is injected to attempt re-locking only when I_avg is greater than or equal to I2 and the phase difference exceeds a predetermined threshold.

[0014] In a device equipped with the above-mentioned mode management device, if I_avg exceeds a third threshold I3 or if the remaining battery charge is less than 30%, chirp sweep in the chirp search mode, which operates only when the above-mentioned phase difference exceeds a predetermined threshold, may be prohibited.

[0015] The actuator may have a displacement of ±200 nm or less, and the displacement may result in a decrease in the balance quality factor of less than 1%.

[0016] In a second aspect of the present invention, there is provided a rate stabilizer for a mechanical timepiece in which the hairspring is not modified, A) A fundamental driver that generates a drive signal synchronized with the balance natural frequency F0, B) A pulse generator and an actuator connected thereto, in which the pulse width tp, amplitude Vp, and duty ratio D0 output by the driver are each kept constant, and which drives the balance by injecting symmetrical pulse energy Ep into two phase windows of phase 0 degrees ±δ and 180 degrees ±δ; C) The drive is executed only under the condition that the continuous time T_cond does not exceed 6 hours, and an amplitude monitoring circuit stops pulse injection if the balance amplitude exceeds the upper limit θ_max (75 degrees) during execution; D) a conditioning control circuit that roughly adjusts the balance frequency within ±1000 ppm only when the execution conditions for the drive are met; wherein the pulse width tp, amplitude Vp and duty ratio D0 do not change during driving and after driving has ended, and the stiffness or damping of the balance and hairspring are not periodically modulated.

[0017] Here, the conditioning control circuit may be configured to automatically switch to one of the following rate correction modes at the time when the balance amplitude has attenuated to the reference amplitude after the end of driving: a rate correction mode in which the control circuit statistically updates the pulse injection probability P(t) (0≦P≦1), which is the probability of injecting the external pulse force, based on the phase difference with an external reference oscillator, or controls the average duty ratio D(t) or drive frequency to perform rate correction; a rate correction mode in which the control circuit detects the injection phase and performs rate correction by changing the pulse injection probability P(t) in real time in proportion to the magnitude of the injection phase; a rate correction mode in which the control circuit performs rate correction using only the average duty ratio D(t) based on a one-bit stream generated by a ΔΣ modulator; or a rate correction mode in which the control circuit performs rate correction while pseudo-randomly hopping between a plurality of frequencies ±ΔF_ppm centered on a frequency twice the balance natural frequency F0; or a chirp search mode in which a burst that chirp-sweeps the frequency is injected to attempt re-locking only when the phase difference exceeds a predetermined threshold.

[0018] The actuator may be disposed between the jewel supporting the end of the balance shaft and the hole jewel or on the top surface of the jewel, and an elastic layer may be interposed on at least one surface of the actuator to also serve as a shock absorbing function. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is an image diagram showing the state in which the watch rate stabilizer of this embodiment is incorporated into the main body of a mechanical watch. [Figure 2] Figure 2 is a schematic diagram of a sensor and actuator attached to a conventional vibration mechanism. [Figure 3] FIG. 3 is a cross-sectional view of the area of ​​the end stone and the hole stone, showing the positions where the actuators are arranged in a modified arrangement method. [Figure 4] FIG. 4 is a functional block diagram showing the functional configuration of the control unit. [Figure 5] Figure 5 is a flowchart showing the control flow in which the P(t) probability control of the control unit is placed in the main layer. [Figure 6] FIG. 6 is a flowchart showing the details of the normal mode operation in step A4. [Figure 7] FIG. 7 is a flowchart showing details of the ΔΣ 1-bit quantization mode operation B1 in the auxiliary layer in step A5. [Figure 8] FIG. 8 is a flowchart showing details of the low detune frequency hopping mode operation B2 in the auxiliary layer of step A5. [Figure 9] FIG. 9 is a flowchart showing details of chirp search mode operation B3 in the auxiliary layer of step A5 and the associated pulse generator operation. [Figure 10] FIG. 10 is an image diagram showing the state in which the watch rate stabilizer of this embodiment is incorporated into the main body of a mechanical timepiece. [Figure 11] FIG. 11 is a functional block diagram showing the functional configuration of the control unit. [Figure 12]FIG. 12 is a flowchart showing the operation of the F0 burst conditioning mode operation control unit. DETAILED DESCRIPTION OF THE INVENTION

[0020] A rate stabilizer for mechanical watches that uses an external reference but does not directly inject mechanical vibrations into the balance, and that can stabilize rate over long periods with extremely low power consumption, has been realized by incorporating an external reference oscillator that is separate from the balance of the watch it is installed on, and by controlling it mainly by thinning out external force pulses with a probability P(t) and injecting them into the balance support member, with the fundamental excitation frequency being twice the balance's natural frequency F0 (2F0), and by performing minute phase correction on the external reference oscillator. It should be noted that the various values ​​shown in the examples are merely examples and are not limited to these values, but may be changed as appropriate. [Example]

[0021] FIG. 1 is an image diagram showing a state in which the rate stabilizer for a mechanical timepiece of this embodiment is incorporated into the main body of a mechanical timepiece. This device is configured as a system in which a sensor 1003, an actuator 1004, a control unit 1005, an external reference oscillator 1006, and a power supply block 1007 are added to a mechanical watch body 1001 having a balance oscillator 1002, which is a conventional vibration mechanism consisting of a balance wheel, a hairspring, a bridge, a balance cock, etc. The control unit 1005 is electrically connected to the other components to receive detection signals, transmit control signals, and control the supply of power. The power supply block 1007 is made up of a button battery (1.55V), a DC-DC booster that boosts the voltage of the button battery to 10V, and a current monitor that monitors the average current I_avg.

[0022] A sensor 1003 and an actuator 1004 are attached to the balance oscillator 1002 . Figure 2 is a schematic diagram of the sensor and actuator attached to the balance oscillator. Sensor 1003 is built into mechanical watch body 1001 and detects the vibration of balance wheel 2001. Actuator 1004 is placed between mechanical watch body 1001 and suspended balance cock 2002 and applies a predetermined vibration.

[0023] (sensor) A CMOS optical motion sensor is used for sensor 1003. The sensor uses pulse-drive of a specified VCSEL (Vertical-Cavity Surface-Emitting Laser) and performs correlation calculations of the scattered light pattern with a light-receiving pixel array to obtain vibration data including the frequency and amplitude of the balance wheel, and transfers the data to the control unit.

[0024] (actuator) The piezoelectric element employed as the actuator 1004 is a multi-layer PZT stack, which injects a 2F0 band external pulse force into the balance cock in response to an external pulse force command output by the control unit 1005. Here, a piezoelectric element is used as the actuator, but the actuators that can be used in the present invention are not limited to this, and magnetostrictive elements, electrostatic actuators, shape memory alloy actuators, electromagnetic coils, micromachine actuators, etc. can also be used as appropriate. Furthermore, the actuator is positioned between the mechanical timepiece body 1001 and the balance cock 2002, but the positioning method that can be used in the present invention is not limited to this, and a method of positioning it between or on the surface of the jewels, hole jewels, etc. that make up the balance cock can be appropriately used.

[0025] As a variation of the arrangement method, an arrangement method can be adopted in which the actuator is arranged on the lower surface or upper surface of the jewel that supports the end of the balance shaft, and an elastic layer is interposed on at least one surface of the actuator, thereby also providing a shock absorbing function.

[0026] (Modification of actuator arrangement method) Figure 3 is a cross-sectional view of the area of ​​the end jewel and the hole jewel, showing the position of the actuator in a modified arrangement. The end of the balance shaft 3000 is supported by end jewel 3001 and hole jewel 3002. Here, the lower surface of the end jewel indicated by 3003 and the upper surface of the end jewel indicated by 3004 can be used as positions for arranging the actuator. When the method of disposing the bearing on the lower surface 3003 of the bearing stone is adopted, the actuator displaces the bearing stone in the direction parallel to the axis at a drive frequency of 2F0.

[0027] (control unit) The operation of each functional component shown here is realized by executing a control program such as pre-installed firmware on a specified processor or dedicated hardware circuit, and by cooperating with various devices that constitute the device. A microcontroller unit (hereinafter referred to as MCU) is used for the control unit 1005. The MCU refers to an external reference, calculates the phase difference Δφ with respect to the balance phase using a PLL method, and controls the pulse width, amplitude, duty ratio, and phase of the pulse control profile output to the pulse generator so that Δφ becomes zero.

[0028] FIG. 4 is a functional block diagram showing the functional configuration of the control unit. The schematic configuration includes a statistically driven control unit 4000 and a pulse generator 4008 that outputs an external force pulse command in accordance with a pulse control profile and a drive trigger generated by the statistically driven control unit. The statistically driven control unit 4000 comprises a phase difference Δφ calculation unit 4001 , a probability P(t) update unit 4002 , a ΔΣ Duty control unit 4003 , a frequency table 4004 , a chirp control unit 4005 , an I_avg & amplitude monitoring unit 4006 , and a mode selection unit 4007 .

[0029] A phase difference Δφ calculation unit 4001 calculates the phase difference Δφ between the external reference signal and the vibration of the balance oscillator, and sends the result to a probability P(t) update unit 4002 . The probability P(t) update unit 4002 updates the pulse injection probability P(t) in real time and transmits it to the pulse generator.

[0030] The ΔΣ Duty control unit 4003 quantizes and noise-shapes the updated probability P(t) into a 1-bit drive trigger sequence d(n) using ΔΣ secondary modulation, and also generates a pulse control profile including the pulse width tp, amplitude Vp, etc. by referring to the frequency table 4004, and sends it to the pulse generator. Additionally, it provides real-time d(n) sequences to the pulse generator during initial setup / recalibration of the pulse control profile.

[0031] The frequency table 4004 stores the balance frequency (F0 and frequency after temperature compensation) of the target mechanical watch, fine adjustment frequencies (F0+ΔF1, F0+ΔF2, ...), frequencies of high-order synchronization trains (k·F0, k=2 to 10), and chirp frequencies.

[0032] Only when the phase difference Δφ exceeds a predetermined threshold value, the chirp generation unit 4005 refers to the frequency table 4004, generates a pulse control profile including a predetermined chirp signal, and supplies it to the pulse generator. The I_avg & amplitude monitor 4006 monitors the average current I_avg supplied from the power supply block 1007 and the vibration amplitude of the balance wheel acquired by the sensor, and if it deviates from the allowable range, it provides feedback to the above-mentioned sections. The mode selection section 4007 compares the average current I_avg with the rated current of the power supply block, and also compares the vibration amplitude of the balance wheel with the upper limit amplitude, and selects the operation mode of the control unit. The pulse generator 4008 outputs an external force pulse command to the actuator according to the pulse control profile and drive trigger generated in the selected operation mode (only the drive trigger when the pulse control profile is not generated).

[0033] FIG. 5 is a flowchart showing a control flow in which the control of the injection probability P(t) of the control unit is placed in the main layer. In step A1, the frequency F0 and amplitude associated with the movement of the balance wheel are measured by the sensor 1003. In step A2, the fundamental excitation frequency is calculated and determined by the control unit as F0x 2 . In step A3, a reference frequency is received from the external reference oscillator 1006, the phase related to the operation of the balance wheel is estimated, and the phase difference Δφ from the reference frequency is calculated. In step A4, the control unit updates the injection probability P(t) in proportion to the phase difference Δφ, and performs core control (hereinafter referred to as normal mode operation) in which a pulse control profile and a drive trigger are generated to inject a 2F0 band external force pulse into the balance cock with the injection probability P(t) that sets P=0 when the amplitude upper limit A>A_max. In step A5, the control unit selects and activates the operation of the auxiliary layer, modulates the fundamental excitation frequency (2F0) in proportion to the calibration amount generated by the operation of the activated operation mode, performs phase conversion, and generates a pulse control profile and a drive trigger.

[0034] Details of the action selection and activation of the auxiliary layer in step A5 are as follows. The power monitor and finite state machine (hereinafter referred to as FSM) of the power supply block 1007, which measures the average current consumption I_avg, autonomously switch between ΔΣ1 bit stream mode operation B1, low detune frequency hopping mode operation B2, and chirp search mode operation B3 depending on the I_avg threshold, and activate the mode.If the mode is not activated, the operation of step A5 is skipped, and the pulse control profile and drive trigger generated in step A4 are sent to the pulse generator. Here, the first threshold I1, the second threshold I2, and the third threshold I3 are set in descending order of power, and the average current consumption I_avg is measured. If I_avg is less than the first threshold I1, ΔΣ1 bitstream mode operation B1 is selected; if I_avg is greater than or equal to I1 and less than the second threshold I2, low detune frequency hopping mode operation B2 is selected; and if I_avg is greater than or equal to I2, chirp search mode is selected. Furthermore, chirp sweep is prohibited when I_avg exceeds a third threshold I3 or when the remaining battery capacity is less than 30%.

[0035] In the ΔΣ1 bit stream mode operation B1, the control unit quantizes the injection phase with a ΔΣ2-order loop (64 kHz) and drives the pulse generator with a 1 / 0 bit sequence. This is a rate correction mode in which rate correction is performed only with the average duty ratio D(t) based on the 1 bit stream generated by the ΔΣ modulator.

[0036] The low detune frequency hopping mode operation B2 is performed by the control unit: 2 This is an operation in which eight frequencies of F0±{-30,-20,-10,-5,+5,+15,+25,+30} ppm are hopped using a linear feedback shift register (hereinafter referred to as LFSR). This is a rate correction mode in which rate correction is performed by pseudo-randomly hopping multiple frequencies of ±ΔF_ppm centered on twice the balance's natural frequency F0.

[0037] In the chirp search mode operation B3, the control unit injects a burst that chirp-sweeps the frequency to relock only when the phase difference exceeds a predetermined threshold. This is an operation mode in which the balance oscillator is locked to the minimum amplitude point with a ±ΔF_ppm chirp only when the phase difference exceeds the threshold.

[0038] In step A6, the control unit generates a pulse control profile and a drive trigger generated by the normal mode or the mode operation of the selected / activated auxiliary layer, and outputs them to the pulse generator.

[0039] In step A7, the pulse generator generates a pulse external force command in accordance with the received pulse control profile and drive trigger, and outputs the command to the actuator.

[0040] In step A8, an external pulse force is applied to the balance cock by the actuator in accordance with the external pulse force command.

[0041] In step A9, the control unit repeats the operations from step A1.

[0042] (Normal Mode Operation) Figure 6 is a flowchart showing details of the normal mode operation of step A4. In step C1, the control unit acquires the reference frequency φ_ref from the external reference oscillator 1006. Furthermore, in step C2, where the frequency φ_meas and amplitude A of the balance oscillator are acquired from the sensor 1003, the control unit calculates the phase difference Δφ between the reference frequency φ_ref and the frequency φ_meas acquired by the sensor. In step C3, the control unit generates an injection probability P(t) proportional to the phase difference based on Equation 1. As shown in Equation 2, when the acquired amplitude A is within the upper amplitude limit, the injection probability P(t) is proportional to the phase difference Δφ, and when the amplitude A exceeds the upper amplitude limit, the injection probability is set to 0.

[0043]

number

[0044]

number

[0045] In step C4, the control unit generates a pseudorandom number R(t) ranging from 0 to 1. In step C5, the control unit uses a comparator to compare the pseudorandom number R(t) with the injection probability P(t) based on Equation 3, and determines whether to inject an external force pulse depending on the comparison result, thereby quantizing the drive trigger for the external force pulse injection.

[0046]

number

[0047] When the auxiliary layer in step A5 is skipped, the pulse generator generates a pulse external force command according to the drive trigger quantized in the normal mode operation in step A4 and according to a preset pulse control profile, and outputs the pulse external force command to the actuator. The pulse control profile at this time is set as follows: The pulse width tp is set to approximately 2 ms (range 1.5 to 3 ms), the amplitude Vp to approximately 10 V (range 8 to 12 V), and the duty ratio D0 to 20 to 30%, and the same energy Ep is injected symmetrically in two windows of phase 0 degrees ±10 degrees and 180 degrees ±10 degrees. Here, the pulse width tp and amplitude V_p are fixed, the instantaneous energy Ep of each excitation pulse is kept constant, and the rate correction is performed only by the pulse injection phase. Alternatively, the control circuit may detect the pulse injection phase and change the pulse injection probability P(t) in real time in proportion to the magnitude of the detected injection phase.

[0048] (ΔΣ 1-bit quantization mode operation B1) Figure 7 is a flowchart showing the details of ΔΣ 1-bit quantization mode operation B1 in the auxiliary layer of step A5. In step D1, the control unit acquires the reference frequency φ_ref from the external reference oscillator 1006. In step D2, the balance oscillator frequency φ_meas and amplitude A are acquired from the sensor 1003. The control unit then calculates the phase difference Δφ between the reference frequency φ_ref and the frequency φ_meas acquired by the sensor. In step D3, the 64 kHz sampling second-order ΔΣ modulator in the ΔΣ Duty control unit quantizes the detected phase error Δφ into a 1-bit drive trigger sequence d(n), applies noise shaping, and performs high-resolution encoding of the phase error.

[0049] (Low Detune Frequency Hopping Mode B2) FIG. 8 is a flowchart showing details of the low detune frequency hopping mode B2 in the auxiliary layer in step A5.

[0050] In step E1, the control unit acquires the reference frequency φ_ref from the external reference oscillator 1006. In step E2, the frequency φ_meas and amplitude A of the balance oscillator are acquired from the sensor 1003. The control unit then calculates the phase difference Δφ between the reference frequency φ_ref and the frequency φ_meas acquired by the sensor. In step E3, the control unit determines the probability P(t) using the phase difference Δφ, the injection probability average P_avg, and the FSM state, and converts it into a drive trigger sequence d(n). In step E4, the control unit generates a pseudorandom index (0-7) from a 15-bit LFSR. In step E5, the control unit references the drive frequency by index in the frequency table, generates a pulse control profile hopping eight frequencies in 2F0±{-30,-20,-10,-5,+5,+15,+25,+30} ppm, including pulse width tp, amplitude V_p, phase window ID, timer reload value, etc., and a drive trigger sequence d(n), and sends these to the pulse generator.

[0051] The pulse generator receives the pulse control profile and drive trigger sequence d(n), generates a phase window mask of 0°±δ·180°±δ based on the drive frequency and phase window ID, and ANDs the phase window mask with the drive trigger sequence d(n) to determine whether to fire. It then outputs pulses according to tp·Vp in the pulse control profile at the permitted timing, supplying the specified number of pulses to the actuator within the hopping period T_h. Through the above steps and the operation of the pulse generator, pseudo-random hopping is performed within 2F0±ΔF_ppm (≦50 ppm).

[0052] (Chirp Search Mode Operation B3) FIG. 9 is a flowchart showing details of chirp search mode operation B3 in the auxiliary layer of step A5 and the associated pulse generator operation.

[0053] In step F1, the control unit acquires the reference frequency φ_ref from the external reference oscillator 1006. In step F2, the control unit acquires the balance oscillator frequency φ_meas and amplitude A from the sensor 1003. The control unit calculates the phase difference Δφ between the reference frequency φ_ref and the frequency φ_meas acquired by the sensor. In step F3, the control unit generates a relock trigger signal to initiate a relock operation if the absolute value of the phase difference Δφ exceeds a predetermined threshold (here, π / 8) and the remaining battery capacity is greater than 30% (the average current is greater than the second threshold I2). In step F4, the control unit starts the chirp burst generator 4005 upon receiving the relock trigger signal and sets the pulse control profile of the drive frequency and the pulse permission bit string. Here, the drive frequency is set to a linear chirp of 2F0 ±200 ppm / 50 ms, the pulse permission is fixed to continuous firing mode (P(t) = 1), and no thinning is performed.

[0054] In step F5, the pulse generator calculates phase windows of 0°±δ and 180°±δ in synchronization with the instantaneous frequency during the chirp, and outputs them as a gating mask. In step F6, the pulse generator ANDs the phase window mask and pulse permission (P(t)=1), and generates continuous external force pulses while each window is open, which are then injected into the actuator.

[0055] In step F7, the control unit monitors the balance amplitude and phase difference Δφ in real time and detects the moment when the amplitude exceeds a predetermined minimum value and converges to Δφ = 0 (the minimum amplitude point locking condition is met). In step F8, when the minimum amplitude point locking condition is met, the control unit issues a stop signal and sends it to the chirp generation unit 4005. This stops the chirp frequency sweep and continuous pulse emission. [Example]

[0056] The second embodiment is a rate stabilizer for a mechanical timepiece that incorporates the statistically driven control operation of the first embodiment, and executes an F0 burst conditioning mode operation under predetermined conditions, and when predetermined transition conditions are met, transitions to a correction mode operation in which correction is made only by the pulse injection phase Δφ shown in the first embodiment. FIG. 10 is an image diagram showing the state in which the watch rate stabilizer of this embodiment is incorporated into the main body of a mechanical timepiece. This device is configured as a system in which a sensor 10003, an actuator 10004, a control unit 10005, an external reference oscillator 10006, and a power supply block 10007 are added to a mechanical watch body 10001 having a balance oscillator 10002, which is a conventional vibration mechanism consisting of a balance wheel, a hairspring, a bridge, a balance cock, etc. The control unit 10005 is electrically connected to other components to receive detection signals, transmit control signals, and control the supply of power. The power supply block 1007 is made up of a button battery (1.55V), a DC-DC booster that boosts the voltage of the button battery to 10V, and a current monitor that monitors the average current I_avg.

[0057] A sensor 10003 and an actuator 10004 are attached to the balance oscillator 10002.

[0058] (sensor) A CMOS optical motion sensor is used for sensor 10003. The sensor uses pulse-drive of a specified VCSEL (Vertical-Cavity Surface-Emitting Laser) and performs correlation calculations of the scattered light pattern with a light-receiving pixel array to obtain vibration data of the balance wheel and transfer the data to the control unit.

[0059] (actuator) The piezoelectric element used as actuator 10004 is a multi-layer PZT stack, which injects a 2F₀-band pulse force into the balance cock in response to the pulse force command output by control unit 10005. Here, a piezoelectric element is used as the actuator, but the actuators that can be used in the present invention are not limited to this, and magnetostrictive elements, electrostatic actuators, shape memory alloy actuators, electromagnetic coils, micromachine actuators, etc. can also be used as appropriate. Furthermore, the actuator is positioned between the mechanical watch body 10001 and the balance cock of the balance oscillator 10002, but the positioning method that can be used in the present invention is not limited to this, and a method of positioning between or on the surface of the jewels, hole jewels, etc. that make up the balance cock can be appropriately used.

[0060] (control unit) The operation of each functional component shown here is realized by executing a control program such as pre-installed firmware on a specified processor or dedicated hardware circuit, and by cooperating with various devices that constitute the device. A microcontroller unit (hereinafter referred to as MCU) is employed as the control unit 10005. It controls the pulse width, amplitude, duty ratio, and phase of the pulse control profile required for the external force pulse command.

[0061] FIG. 11 is a functional block diagram showing the functional configuration of the control unit. The general configuration is comprised of a rate error detection unit 11001, an F0 burst conditioning mode operation control unit 11002, a statistical drive control unit 11003, a first pulse generator 11004, and a second pulse generator 11005 that outputs an external force pulse voltage to the actuator based on an external force pulse command output from the normal control unit. In the rate error detection unit 11001, when the error rate (also referred to as e_rate in the formula) indicates a value that satisfies the following formula 4, a rate error is detected, the F0 burst conditioning mode request flag is set, and the operation of the F0 burst conditioning mode operation control unit is started.

[0062]

number

[0063] F0 burst conditioning control unit 11002 is composed of functional components including fundamental driver 11006, conditioning control unit 11007, monitoring unit 11007, and automatic mode switching unit 11000, and drives first pulse generator 11004. The fundamental driver 11006 generates a drive signal synchronized with the balance natural frequency F0.

[0064] The conditioning control unit 11007 controls the external force pulse command output by the first pulse generator to roughly adjust the balance frequency within ±1000 ppm only when the drive execution condition of "amplitude < 70 degrees and battery remaining capacity rate > 40%" is met. Here, coarse adjustment is performed by driving the actuator so that the pulse width tp, amplitude Vp, and duty ratio D0 output by the fundamental driver are each kept constant, and symmetrical pulse energy is injected into the balance in two phase windows: phase 0 degrees ±δ and phase 180 degrees ±δ.

[0065] The monitoring unit 11008 monitors the average current I_avg supplied from the power supply block 1007 and the vibration amplitude of the balance wheel, and provides feedback to each functional component. It also monitors to stop pulse injection if the balance amplitude exceeds the upper limit θ_max (75 degrees) during burst execution, which will be described later.

[0066] The automatic mode switching unit 11009 switches the operating mode according to the condition shown in the following formula 5. If the condition is not met, the operation mode is switched to the normal mode of the statistically driven control unit 11003, and the rate stabilizer of this embodiment is operated. If formula 5 is met, an external force pulse command is output to the first pulse generator.

[0067]

number

[0068] The first pulse generator 11006 generates an external force pulse command so that the pulse width tp, amplitude Vp, and duty ratio D0 of the drive signal output by the fundamental driver are each kept constant, and symmetrical pulse energy is injected into the balance wheel in two phase windows of phase 0 degrees ±δ and 180 degrees ±δ, and outputs the command to the actuator.

[0069] The normal control unit 11003 is the same as the statistical correction operation control unit 4000 in the first embodiment. The normal control unit 11003 is composed of a phase difference Δφ calculation unit 11009, a probability P(t) update unit 11010, a ΔΣ Duty control unit 11011, a frequency table 11012, a chirp generation unit 11013, an I_avg & amplitude monitoring unit 11014, and a mode selection unit 11015, and the operation of these units is the same as that described in the embodiment.

[0070] (F0 Burst Conditioning Operation Mode) Figure 12 is a flowchart showing the operation of the F0 Burst Conditioning Mode Operation Control Unit. According to the operation flow shown here, coarse adjustment is performed using symmetrical pulses synchronized with the balance natural frequency F0.

[0071] In step G1, the conditioning control unit acquires the real-time frequency of the balance oscillator measured by the sensor and the balance amplitude A. In step G2, if the absolute value of the rate error exceeds 60 ppm, the conditioning control unit sets the F0 burst conditioning mode request flag. In step G3, the conditioning control unit determines whether the burst start conditions are met: balance amplitude A is less than 70 degrees and the remaining battery capacity is greater than 40%. The burst sequence is started. In step G4, if the burst start conditions are met, the conditioning control unit starts the burst sequence. In step G5, the conditioning control unit increments the phase offset from the first pulse of the burst in steps (ladder-like) from 0 degrees to +90 degrees in units of several degrees. In step G6, the conditioning control unit measures the temp amplitude A in real time at each stage of the burst, evaluates whether A has increased or decreased from the previous step, and detects the stage at which the amplitude no longer increases, i.e., the phase offset at which it reaches a local maximum (hereinafter referred to as the peak phase offset). In step G7, the conditioning control unit fixes the phase difference to the peak phase offset, and injects the remaining pulses thereafter (e.g., from the 150th pulse out of 512 onwards) at the peak phase offset. In step G8, the conditioning control unit ends the burst after a predetermined number of pulses have been consumed, and enters a rest period.

[0072] (Burst Configuration) The number of pulses per burst is set to 400 to 600 (standard value 512, ≈128 seconds), the rest time between bursts T_rest is set to 5 to 15 minutes, and the maximum number of bursts N_max is limited to 4 to 8 (total continuous operation time is within 6 hours). The monitoring unit 11008 monitors and stops pulse injection if the temp amplitude exceeds the upper limit θ_max (75 degrees) during burst execution. In this embodiment, one burst = 512 F0 pulses (≈128 seconds), and a rest time T_rest = 10 minutes is forcibly inserted after the end of the burst to prevent heat accumulation. The maximum number of bursts N_max = 6 (total operation time ≦4 hours).

[0073] In step G9, the conditioning control section recalculates the rate error at the end of the pause and determines whether the condition shown in equation 6 is met.

[0074]

number

[0075] In step G10, if the conditioning control unit determines that the absolute value of the error rate is within 10 ppm and satisfies Equation 6, the F0 burst conditioning operation mode is terminated and the system transitions to a correction mode in which correction is performed only by the pulse injection phase of the statistical drive control unit. If Equation 6 is not satisfied, the system transitions to the next burst.

[0076] (Implementation results) When the rate stabilizer of this embodiment was implemented and tested, an unadjusted movement with a daily rate of +120 seconds was roughly adjusted to +4 seconds / day using three F0 bursts, and the parametric fine adjustment mode achieved ±0.3 ppm / day.

[0077] (Evaluation by operation mode) The results of evaluation of the 28800 bph prototype by operating mode are as follows: In the normal mode by controlling the injection probability P(t), ±0.8 ppm / day was achieved. In ΔΣ1 bitstream mode operation, ±0.3 ppm / day was achieved. The average current was 9.2 microA, and a peak of 12 microA was observed during chirp search mode operation. Table 1 shows the current effect and rate stability ratings for each mode. The rating is based on a 5-point scale, with the number of stars representing half a star. Five stars represent the best and least burdensome rating, and one star represents the worst and most burdensome rating.

[0078] [Table 1]

[0079] Here, the evaluation axes are defined as follows: Short-term accuracy: Evaluation of rate fluctuations over a window of several tens of seconds to several minutes. Long-term accuracy: Evaluation of the average daily / weekly residual error over 24 hours to several days. Postural tolerance: Evaluation of step return after posture test. Average power consumption: Evaluation of the additional current and drive energy in the normal locked state. Peak power: Evaluation of the instantaneous power consumption during maximum load such as search and reacquisition. Recovery from release: Evaluation of the ability and speed to return to the resonance point after a large release due to impact or temperature change. Mechanical stress: Evaluation of balance Q value decline, bearing load, and wear (the more stars, the less stress). Implementation complexity: Evaluation of the amount of work and cost required for the hardware / firmware (the more stars, the simpler the implementation). Quietness: Evaluation of the amount of driving noise and vibration (the more stars, the quieter the unit).

[0080] (Comparison of periodic and statistical control methods) The theoretical basis for the effectiveness of the rate correction described in Examples 1 and 2 is as follows. However, the formula shown here is a hypothetical model in which the average effect of the external force pulse is replaced with "equivalent stiffness" for the convenience of analysis, and in reality, the mainspring spring constant k_e does not mechanically change periodically. If the equivalent stiffness of the balance is k(t)=ke[1+ε cos(2ωet+δφ)], then within the stable region of the Mathieu equation (ε≪1, ζ≪0.01), the amplitude gain G≒ε / 2 is obtained. Fine-tuning δφ shifts the average angular velocity ω0+Δω, and Δω / ω0≒(ε / 2) tan(δφ). Using this relationship, the rate can be linearly corrected within a range of ±5 seconds / day. Therefore, the device of this embodiment differs from the conventional rigid period modulation method in that it corrects the average angular velocity by a non-contact impulse.

[0081] Table 2 is a comparative evaluation table of periodic control methods and statistical control methods. The evaluation is on a 5-point scale with the number of stars, where a star means half a star.

[0082] [Table 2]

[0083] By providing this rate stabilizer, it is possible to improve the accuracy of existing mechanical watches to a level comparable to that of quartz watches without removing the balance or escapement. Furthermore, because the hairspring is not modified, the aesthetics and traditional mechanics of the watch are not compromised, significantly improving convenience and reliability. Constant instantaneous energy suppresses Q-factor degradation to less than 1%. Furthermore, digital control of ΔΣ1 bitstream mode operation, narrow band hopping mode operation, and chirp search mode operation enables rate stability of ±0.3 ppm / day and average current consumption of 9 to 10 microamperes. [Industrial Applicability]

[0084] The device of the present invention can be applied to all mechanical timepieces that require long-term rate stability, such as marine chronometers for ships and mechanical clocks, in addition to high-end mechanical wristwatches. [Explanation of symbols]

[0085] 1001 Mechanical watch body 1002 balance oscillator 1003 Sensor 1004 Actuator 1005 control unit 1006 External Reference Oscillator 1007 Power Block

Claims

1. In a rate stabilizer for a mechanical timepiece in which the hairspring is not modified, a) at least one detection means selected from an optical reflection sensor or a magnetic sensor for detecting the balance amplitude A and phase φ in a non-contact manner; b) a pulse generator that outputs a pulse external force command having a constant pulse width tp, a constant amplitude Vp, and a constant duty ratio D0 at an even half-cycle position of the balance natural frequency F0; c) an actuator that applies a pulse external force to the balance support in response to the pulse external force command; d) a control circuit including a circuit that operates in a rate correction mode for statistically updating a pulse injection probability P(t) (0≦P≦1), which is the probability of injecting the external pulse force, based on the phase difference with an external reference oscillator, or for correcting the rate by controlling the average duty ratio D(t) of the quantized external pulse force or the drive frequency of the external pulse force, and a circuit that sets P(t)=0 and stops excitation when the balance amplitude exceeds an upper limit A_max; Equipped with 10. A rate stabilizer, characterized in that said device does not periodically modulate the stiffness, inertia, quality factor or position of the rest point of the balance and hairspring.

2. 2. The rate stabilization device according to claim 1, wherein the control circuit operates in a rate correction mode in which the rate correction is performed by detecting an injection phase of the injection and varying the pulse injection probability P(t) in real time in proportion to the magnitude of the injection phase.

3. 2. The rate stabilizing device according to claim 1, wherein said control circuit operates in a rate correction mode in which rate correction is performed using only said average duty ratio D(t) based on a one-bit stream generated by a ΔΣ modulator.

4. 2. A rate stabilizing device according to claim 1, wherein said control circuit operates in a rate correction mode in which rate correction is performed while pseudo-randomly hopping among a plurality of frequencies within a range of ±ΔF ppm centered on a frequency twice the balance wheel natural frequency F0.

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