JP3601268B2 - Electronically controlled mechanical clock - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
In the present invention, the mechanical energy when the mainspring is opened is converted into electric energy by the generator, and the rotation control means is operated by the electric energy to control the rotation cycle of the generator, thereby being fixed to the wheel train. The present invention relates to an electronically controlled mechanical timepiece that accurately drives a hand.
[0002]
[Background Art]
A pointer fixed to the wheel train by converting mechanical energy when the mainspring is released into electric energy by a generator and activating a rotation control means by the electric energy to control a current value flowing through a coil of the generator. There are known electronically controlled mechanical timepieces that accurately drive and display time accurately, such as those described in Japanese Patent Publication No. Hei 7-119812 and Japanese Patent Laid-Open Publication No. Hei 8-50186.
[0003]
Japanese Patent Publication No. 7-198812 discloses an angle range in which the brake is turned off and the rotation speed of the rotor is increased to increase the amount of power generation during one rotation of the rotor, that is, every cycle of the reference signal. An angle range in which the power is applied at a low speed is provided, and the speed is adjusted so as to compensate for a decrease in the generated power during braking while improving the generated power while the rotation speed is high.
[0004]
Japanese Patent Application Laid-Open No. H8-50186 discloses a technique of counting a reference pulse and a measurement pulse detected with rotation of a rotor, comparing the number of reference pulses with the number of measurement pulses, In the first state in which the number of pulses is smaller than the number of measurement pulses, the control unit generates a brake signal having a pulse width set in response to the measurement pulse to perform brake control.
[0005]
[Problems to be solved by the invention]
However, in the device described in Japanese Patent Publication No. Hei 7-119812, the brake ON control and the brake OFF control are always performed during one rotation of the rotor, that is, for each reference signal. When the control is greatly deviated, for example, the amount of rotation control of the rotor for each reference signal cannot be so large, and there is a problem that it takes time to shift to a normal control state and the response is low.
[0006]
Also, the brake signal generated in each reference signal has a constant pulse width, so that the brake amount for each reference signal is constant even when the control is largely deviated. Therefore, it takes a long time to shift to a normal control state, and there is the same problem that responsiveness is low.
[0007]
In addition to the circuit for detecting the first and second states by counting and comparing the reference pulse and the measurement pulse, a control means for generating a brake signal having a pulse width set in response to the measurement pulse is additionally provided. It has to be provided, and there is a problem that the configuration is complicated and the cost is high.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to provide an electronically controlled mechanical timepiece in which the speed control response is fast and the cost can be reduced.
[0009]
[Means for Solving the Problems]
An electronically controlled mechanical timepiece according to the present invention includes a mainspring, a generator for converting mechanical energy of the mainspring transmitted via a train wheel into electric energy, a pointer coupled to the wheel train, and the converted electric energy. An electronically controlled mechanical timepiece having a rotation control means for controlling a rotation cycle of the generator driven by a clock generator, wherein the rotation control means uses a quartz oscillator or the like to generate a reference signal serving as a time standard of the timepiece. A circuit, a rotation detection circuit for detecting rotation of a rotor of the generator, and a speed comparison for comparing a reference signal output of the oscillation circuit and a rotation detection signal output of the rotation detection circuit for each period of a rotation waveform of the rotor. When the cycle of the rotation detection signal is shorter than the cycle of the reference signal in the circuit and the speed comparison circuit, a brake is applied to the rotor during the next one cycle of the rotor to detect the rotation. No. If the period is longer than the period of the reference signal is to basically to have the next one cycle period of the rotor, and a brake control circuit for controlling so as not apply braking to the rotor.
[0010]
The electronically controlled mechanical timepiece of the present invention drives the hands and the generator with a mainspring, and regulates the rotation speed of the rotor, that is, the hands, by applying a brake to the generator with the braking means of the rotation control means.
[0011]
At this time, the rotation control means of the generator compares the reference signal output from the oscillation circuit with the rotation detection signal output from the rotation detection circuit for each period of the rotor rotation waveform in the speed comparison circuit, and the comparison result When the cycle of the rotation detection signal is shorter than the cycle of the reference signal, that is, when the rotation speed of the rotor is faster than the reference signal output, the brake control circuit applies the brake to the rotor during the next one cycle of the rotor. If the cycle of the rotation detection signal is longer than the cycle of the reference signal, that is, if the rotation speed of the rotor is lower than the output of the reference signal, no brake is applied to the rotor during the next one cycle of the rotor. Control.
[0012]
Therefore, for example, when the torque of a mechanical energy source such as a mainspring is large and the rotation of the generator is progressing, and the rotation speed of the rotor continues to be higher than the reference signal output, the rotation speed becomes the reference speed. Until the signal output becomes slower, the brake is continuously applied, so that the speed can be quickly adjusted to a normal rotation speed, and control with a quick response can be performed.
[0013]
Further, since the brake control is set by detecting only whether the period of the rotation detection signal of the rotor is shorter or longer than the period of the reference signal, the configuration of the rotation control means can be simplified and the cost can be reduced.
[0014]
At this time, the speed comparison means includes a signal level change timing after a predetermined time from the rotation detection signal of the reference signal output which is output in accordance with the rotation detection signal output from the rotation detection circuit; It is preferable to compare the cycle of the rotation detection signal of the rotor with the cycle of the reference signal by comparing the output timing of the next rotation detection signal.
[0015]
If the reference signal output is output in accordance with the rotation detection signal, the next rotation detection signal and the reference signal output can always be compared at a fixed timing. For this reason, the comparison between the rotation detection signal and the reference signal output can always be performed accurately and with a constant reference. Particularly, even when the rotor is not rotating stably immediately after the start of the generator, it can be reliably and accurately performed. Thus, it is possible to perform appropriate brake control by grasping the rotation state of the rotor.
[0016]
Further, the brake control circuit may perform chopper brake control when applying a brake to the rotor. Performing the chopper brake control has the advantage that the brake torque can be increased while maintaining the generated power at or above a certain level.
[0017]
Further, the electronically controlled mechanical timepiece of the present invention further includes an up / down counter in which the rotation detection signal and the reference signal are input to an up-count input and a down-count input, respectively. When the cumulative error detection output correspondingly output is in the ON state, a lead / lag output for controlling the brake prior to the output of the brake control circuit is output according to the counter value. May be what you have.
[0018]
If such an up-down counter is provided, the cumulative error can be counted and the brake control can be performed so as to eliminate the error, such as when the generator is started or when a shock is applied to the clock. When the rotation of the rotor greatly shifts, the shift can be eliminated and the normal control state can be quickly returned.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0020]
FIG. 1 is a plan view showing a main part of an electronically controlled mechanical timepiece according to a first embodiment of the present invention, and FIGS. 2 and 3 are sectional views thereof.
[0021]
The electronically controlled mechanical timepiece includes a barrel wheel 1 including a mainspring 1a, a barrel gear 1b, a barrel barrel 1c, and a barrel lid 1d. The outer end of the mainspring 1a is fixed to the barrel gear 1b, and the inner end is fixed to the barrel barrel 1c. The barrel barrel 1c is supported by the main plate 2 and the train wheel bridge 3, and is fixed by a square screw 5 so as to rotate integrally with the square wheel 4.
[0022]
The square wheel 4 meshes with a hammer 6 so as to rotate clockwise but not counterclockwise. The method of rotating the square wheel 4 in the clockwise direction and winding the mainspring 1a is the same as the automatic winding or the manual winding mechanism of the mechanical timepiece, and thus the description is omitted. The rotation of the barrel gear 1b is increased by a factor of 7 to the second wheel 7 and is sequentially increased by a factor of 6.4 to the third wheel 8 and is increased by 9.375 times to the fourth wheel 9 to triple the speed. The speed is increased to the fifth wheel 10 by 10 times and then increased to 6th wheel 11 by 10 times to the rotor 12 by a total of 126,000 times via each of the wheels 7 to 11 forming a gear train. Speed has been increased.
[0023]
The second wheel & pinion 7 is fixed with a cannon pinion 7a, the cannon pinion 7a is fixed with a minute hand 13 for displaying time, and the fourth wheel 9 is fixed with a second hand 14 for displaying time. Accordingly, in order to rotate the second wheel & pinion 7 at 1 rpm and the fourth wheel & pinion 9 at 1 rpm, the rotor 12 may be controlled to rotate at 5 rpm. At this time, the barrel gear 1b becomes 1/7 rph.
[0024]
This electronically controlled mechanical timepiece includes a generator 20 including a rotor 12, a stator 15, and a coil block 16. The rotor 12 includes a rotor magnet 12a, a rotor pinion 12b, and a rotor inertial disk 12c. The rotor inertia disk 12 c is for reducing the fluctuation of the rotation speed of the rotor 12 with respect to the fluctuation of the driving torque from the barrel car 1. The stator 15 is such that a 40,000-turn stator coil 15b is wound around a stator body 15a.
[0025]
The coil block 16 is formed by winding a coil 16b of 110,000 turns around a magnetic core 16a. Here, the stator body 15a and the magnetic core 16a are made of PC permalloy or the like. Further, the stator coil 15b and the coil 16b are connected in series so that an output voltage is obtained by adding the respective generated voltages.
[0026]
Next, a control circuit of the electronically controlled mechanical timepiece will be described with reference to FIGS.
[0027]
FIG. 4 is a block diagram showing an electronically controlled mechanical timepiece according to the present embodiment, and FIG. 5 is a circuit diagram thereof.
[0028]
The AC output from the generator 20 is boosted and rectified through a rectifier circuit 21 composed of boost rectification, full-wave rectification, half-wave rectification, transistor rectification, and the like. The rectifier circuit 21 is connected to a control IC such as a rotation control unit and a load 22 such as a quartz oscillator. In FIG. 4, for convenience of explanation, each functional circuit configured in the IC is described separately from the load 22.
[0029]
The generator 20 is connected in parallel with a braking circuit 23 configured by connecting a braking resistor 23A and an Nch or Pch transistor 23B in series. The rotation control means 50 is connected to the brake circuit 23. Note that a diode may be appropriately inserted into the brake circuit 23 in addition to the braking resistor 23A.
[0030]
The rotation control means 50 includes an oscillation circuit 51, a frequency division circuit 52, a rotation detection circuit 53, a speed (frequency) comparison circuit 54, and a brake control circuit 56.
[0031]
The oscillating circuit 51 outputs an oscillating signal using the crystal oscillator 51A, and the oscillating signal is frequency-divided by the frequency dividing circuit 52 to a certain period. In the present embodiment, as shown in FIG. 5, two frequency divider circuits 52A and 52B are provided. Note that a reference signal may be created using various reference standard oscillation sources or the like instead of the crystal oscillator 51A.
[0032]
The frequency dividing circuit 52A outputs a 16 kHz pulse signal for generating a reset pulse described later. The frequency dividing circuit 52B outputs a reference clock (reference signal) of 10 Hz to the speed comparing circuit 54.
[0033]
As shown in FIG. 5, the speed comparison circuit 54 includes four flip-flops 61 to 64, inverter (inverting) gates 65 and 66, and an AND gate 67.
[0034]
The flip-flops 61 and 62, the inverter gate 65, and the AND gate 67 are used to generate the counter reset pulse 70 in the timing chart of FIG. 6, and correspond to the rising edge of the motor pulse (rotation detection signal). Is output. Each of the flip-flops 61 to 64 is configured to output data to the outputs 1Q to 4Q when the clock falls.
[0035]
The flip-flop 63 is configured to be reset by the counter reset pulse 70 and receive a reference clock from the frequency dividing circuit 52B, which is also reset by the reset pulse 70, at its clock input. In this circuit, since the ground level is set to the H level, an H level signal is output from the output 3Q at the falling of the reference clock (see the timing chart of FIG. 6). Therefore, if the next motor pulse is input and the reset pulse 70 is output before the falling of the reference clock, the output 3Q remains at the L level signal and does not change (see the second cycle from the left in FIG. 6). .
[0036]
The flip-flop 64 to which the output 3Q is input outputs a brake control pulse. Since a motor pulse is input to the clock input of the flip-flop 64 through the inverter gate 66, the flip-flop 64 next to which the H level signal is output from the output 3Q is output. In the cycle, an H level signal (brake control OFF) is output from the output 4Q, and in the next cycle after the L level signal is output from the output 3Q, an L level signal (brake control ON) is output.
[0037]
The output 4Q of the flip-flop 64 is directly output to the gate of the Pch transistor 23B. Therefore, when the L level signal is output from the output 4Q, the transistor 23B is maintained in the ON state, the generator 20 is short-circuited, and the brake is applied.
[0038]
On the other hand, when the H level signal is output from the output 4Q, the gate voltage of the transistor 23B increases, so that the transistor 23B is maintained in the OFF state, and the brake is not applied to the generator 20. Therefore, the speed comparison circuit 54 also serves as the brake control circuit 56.
[0039]
Next, the operation in the present embodiment will be described with reference to the timing chart of FIG.
[0040]
When the motor pulse (rotation detection signal) is detected by the rotation detection circuit 53 after the generator 20 starts operating, first, a reset pulse 70 synchronized with the motor pulse is generated by each of the flip-flops 61 and 62 and the like.
[0041]
The frequency dividing circuit 52B reset by the reset pulse 70 outputs a reference clock (10 Hz) starting from the reset pulse 70 to the flip-flop 63. Therefore, the flip-flop 63 generates a signal that rises after a lapse of a predetermined time (100 msec in this embodiment) from the reset pulse 70 at the output 3Q. However, if the reset pulse 70 is generated by inputting the next motor pulse before the predetermined time elapses, that is, if the rising timing of the next motor pulse is earlier than the falling timing of the reference clock, the flip-flop Since 63 is also reset, output 3Q is maintained at the L level.
[0042]
When the H level signal is output from the 3Q, that is, when the rising timing of the next motor pulse is later than the falling timing of the reference clock, the output 4Q of the flip-flop 64 becomes 1 During the period, a signal (H level signal) for turning off the brake is output, and conversely, when an L level signal is output from 3Q, that is, the rising timing of the next motor pulse is longer than the falling timing of the reference clock. If early, a signal (L level signal) for turning on the brake is output during one cycle of the next motor pulse.
[0043]
Accordingly, when the motor pulse has a shorter cycle than the reference clock, that is, when the rotation speed of the generator 20 is high, the brake circuit 23 of the generator 20 is turned on to apply a brake, and conversely, compared to the reference clock. When the cycle of the motor pulse is long, that is, when the rotation speed of the generator 20 is low, the brake circuit 23 of the generator 20 is turned off and the brake is released, so that the speed of the generator 20 is adjusted.
[0044]
Since the reference signal of the frequency dividing circuit 52B is generated in synchronization with the falling timing of the counter reset pulse 70, there is a time lag from the rising timing of the motor pulse. In this case, the maximum is about 61 μsec, which is very small, and the shift time is almost constant. Therefore, when comparing each motor pulse with the reference signal, the influence can be eliminated.
[0045]
According to this embodiment, the following effects can be obtained.
[0046]
{Circle around (1)} A rotation detection signal (motor pulse) of the rotor 12 is compared with a reference signal (reference clock) to detect whether the period of the rotation detection signal is shorter or longer than the period of the reference signal. Performs a very simple control of applying the brake for the next one cycle of the rotor 12 and not applying the brake if it is long, so that the circuit configuration can be simplified, the parts cost and the manufacturing cost can be reduced, An electronically controlled mechanical clock can be provided at low cost.
[0047]
{Circle over (2)} Since the brake control is performed for each cycle of the rotor 12, for example, if the cycle of the rotation detection signal is shorter than the cycle of the reference signal, the brake can be continuously applied, and the generator 20 can be operated. Even when the rotation cycle at the time of rising of the motor is greatly deviated from the reference cycle, the speed can be quickly approached to the reference speed, and the response of the speed control can be increased.
[0048]
(3) Since the frequency dividing circuit 52B is reset by the reset pulse 70 based on the motor pulse, the motor pulse and the reference signal can be synchronized, and the reference signal to be compared with the motor pulse is always output from the reset pulse 70. Since the cycle can be made constant, the advance / delay of the motor pulse with respect to the reference signal can always be accurately determined to perform brake control.
[0049]
In particular, immediately after the start of the generator 20, since the cycle of the motor pulse is not constant, the phase may deviate from the reference signal to make accurate comparison impossible. Since the reference signal is reset by the reset pulse 70 and is synchronized with the motor pulse, accurate brake control can be performed immediately after the generator 20 is started, and the stability of the system can be secured.
[0050]
(4) Since each cycle of the motor pulse is always compared with the reference signal and is reflected in the brake control of the motor pulse immediately after that, the cycle of generating the motor pulse has a speed fluctuation in the short term, It can be prevented from continuing to fluctuate for a long time. For this reason, there is provided an electronically controlled mechanical timepiece that has no problem in practical use while having a simple configuration without fluctuations in the operation of the time when the electronically controlled mechanical timepiece is operated by human beings due to a change in the speed of the generator 20. can do.
[0051]
Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the same or similar components as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted or simplified.
[0052]
In the present embodiment, as shown in FIG. 7, the output 4Q of the flip-flop 64 has an inverter gate 81, a chopper pulse generation circuit 82 of about several tens Hz to several kHz (for example, 10 Hz to 10 kHz), an inverter gate 81 and a chopper pulse generation. The only difference from the first embodiment is that a choppering circuit 80 including a NAND gate 83 to which the output of the circuit 82 is input is provided.
[0053]
In this embodiment, as shown in the timing chart of FIG. 8, when an L-level signal for turning on the brake circuit 23 is output from the flip-flop 64, the chopper ring circuit 80 provides a chopper brake control output. By turning on and off 23B, generator 20 is also controlled by the chopper brake.
[0054]
In this embodiment as well, the same effects as (1) to (4) of the first embodiment can be obtained, and (5) choppering control is performed. Also, there is an effect that the brake torque can be increased. That is, when the transistor 23B is turned on, a short brake is applied to the generator 20 and energy is applied to the coil of the generator 20 by turning on and off the transistor 23B capable of short-circuiting both ends of the coil of the generator 20. Accumulates. On the other hand, when the transistor 23B is turned off, the generator 20 operates, and the energy stored in the coil is included, so that the electromotive voltage increases. For this reason, when the generator 20 is controlled by choppering, the decrease in the generated power during braking can be compensated for by the increase in the electromotive voltage at the time of switch-off, and the braking torque can be increased while maintaining the generated power at or above a certain level. An electronically controlled mechanical timepiece with a long time can be constructed.
[0055]
Next, a third embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the same or similar components as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted or simplified.
[0056]
As shown in FIG. 9, the present embodiment includes an up / down counter 92 in which a motor pulse is input as an up-count input, and the output (reference signal: 10 Hz) of the frequency divider 91 which is not reset is input as a down-count input. . The up / down counter 92 counts and compares the motor pulse from the start of the generator 20 with the output of the frequency dividing circuit 91, thereby counting the accumulated error of the motor pulse with respect to the reference signal.
[0057]
The up / down counter 92 normally outputs an H level signal, and outputs an L level signal when the counter value exceeds a certain range, that is, when the accumulated error increases, If the accumulated error is in the forward direction of the motor pulse, a signal to turn on the brake (L level signal) is output, and if the accumulated error is in the late direction, a signal to turn off the brake (H level signal) is output. Have been. The lead / lag output is kept at the L level while the accumulated error detection output is at the H level.
[0058]
The accumulated error detection output is input to an AND gate 93 together with the output 4Q of the flip-flop 64, and the output of the AND gate 93 is input to the OR gate 94 together with the advance / delay output.
[0059]
In this embodiment, the motor pulse and the reference signal of the frequency dividing circuit 91 are counted by the up / down counter 92 at the same time when the generator 20 is started. When the count value of the up / down counter 92 is within the set value, that is, when the difference between the count value of the motor pulse and the count value of the reference signal is within a certain range, the flip-flop is used as in the first embodiment. The brake control is performed based on the 64 outputs 4Q.
[0060]
On the other hand, for example, when the generator 20 is rotating quickly and the count value of the motor pulse is larger than the count value of the reference signal and the difference is equal to or larger than the set value, the accumulated error detection output becomes L level. Therefore, the output 4Q of the flip-flop 64 is masked, the output of the AND gate 93 is always at the L level, and the output 4Q is cancelled.
[0061]
For this reason, a signal of a lead / lag output is output to the brake circuit 23, whereby the brake is controlled so as to eliminate the accumulated error. That is, when the count value of the motor pulse is larger than the count value of the reference signal, an L level signal is output and the brake is forcibly turned on, and when the count value of the motor pulse is smaller than the count value of the reference signal. , An H level signal is output and the brake is forcibly turned off.
[0062]
According to this embodiment, the same effects as (1) to (4) of the first embodiment can be obtained, and the following effects are also obtained.
[0063]
{Circle around (6)} Since the up / down counter 92 is provided, it is possible to count the accumulated error of the advance / delay of the motor pulse with respect to the reference signal, and when the accumulated error becomes larger than the set value, the accumulated error is calculated. Brake control can be performed so as to eliminate it, and therefore, when an accumulated error has occurred, normal control can be quickly returned to, and the responsiveness of speed control can be further improved.
[0064]
It should be noted that the present invention is not limited to the above embodiments, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
[0065]
For example, in the third embodiment, the choppering circuit 80 of the second embodiment may be provided on the output side of the OR gate 94 so that the choppering control can be performed in the third embodiment.
[0066]
Further, the specific configurations of the speed comparison circuit 54 and the brake control circuit 56 are not limited to the above embodiments, and may be appropriately set according to the configuration of the brake circuit 23, for example, when the N-channel transistor 23B is used. . The output of the frequency dividing circuit 52A that generates the counter reset pulse 70 is not limited to a 16 kHz pulse signal, and may be set as appropriate according to the rotation cycle of the rotor 12 and the like.
[0067]
Further, the means for comparing the period between the rotation detection signal of the rotor and the reference signal is not limited to those of the above-described embodiments, and may be set as appropriate according to the configuration.
[0068]
【The invention's effect】
As described above, according to the electronically controlled mechanical timepiece of the present invention, the response of the speed control is fast and the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a plan view showing a main part of an electronically controlled mechanical timepiece according to a first embodiment of the invention.
FIG. 2 is a sectional view showing a main part of FIG.
FIG. 3 is a sectional view showing a main part of FIG. 1;
FIG. 4 is a block diagram showing a configuration of the present embodiment.
FIG. 5 is a circuit diagram showing a configuration of a rotation control unit of the embodiment.
FIG. 6 is a timing chart in the circuit of the present embodiment.
FIG. 7 is a circuit diagram showing a configuration of a second embodiment of the present invention.
FIG. 8 is a timing chart in the circuit of the second embodiment.
FIG. 9 is a circuit diagram showing a configuration of a third embodiment of the present invention.
FIG. 10 is a timing chart of the circuit according to the third embodiment.
[Explanation of symbols]
DESCRIPTION OF REFERENCE NUMERALS 1 barrel box 1a mainspring 3 wheel train receiver 7 second wheel 8 third wheel 9 fourth wheel 10 fifth wheel 11 sixth wheel 12 rotor 13 minute hand 14 second hand 15 stator 16 coil block 20 generator 21 rectifier circuit 22 load 23 brake Circuit 23A Braking resistor 23B Transistor 50 Rotation control means 51 Oscillation circuit 51A Quartz oscillator 52, 91, 52A, 52B Frequency divider 53 Rotation detection circuit 54 Speed comparison circuit 56 Brake control circuits 61-64 Flip-flop 70 Counter reset pulse 80 Chopper Ring circuit 82 Chopper pulse generation circuit 92 Up / down counter

Claims (3)

A mainspring, a generator for converting mechanical energy of the mainspring transmitted through the wheel train into electric energy, a pointer coupled to the wheel train, and a rotation cycle of the generator driven by the converted electric energy An electronically controlled mechanical timepiece having a rotation control means for controlling
The rotation control means includes: an oscillation circuit for generating a reference signal serving as a time standard of a clock; a rotation detection circuit for detecting rotation of a rotor of the generator; a reference signal output of the oscillation circuit; and rotation detection of the rotation detection circuit. A speed comparison circuit for comparing the signal output with each cycle of the rotor rotation waveform; and in the speed comparison circuit, when the cycle of the rotation detection signal is shorter than the cycle of the reference signal, the next cycle of the rotor. And a brake control circuit for controlling not to apply a brake to the rotor during the next one cycle of the rotor when the cycle of the rotation detection signal is longer than the cycle of the reference signal. has the speed comparing circuit, the rotation detecting the signal level after the rotation detection signal a predetermined time variation of the circuit reference signal output in accordance with the rotation detection signal outputted from the output timing If, by comparing the output timing of the next rotation detecting signal of the rotation detection signal, the electronically controlled mechanical timepiece, which comprises comparing the period of the periodic reference signal of the rotation detection signal. 2. The electronically controlled mechanical timepiece according to claim 1, wherein the brake control circuit performs chopper brake control when applying a brake to the rotor. 3. The electronically controlled mechanical timepiece according to claim 1, further comprising an up / down counter for inputting the rotation detection signal and the reference signal to an up count input and a down count input, respectively. Outputs a lead / lag output according to the counter value, which controls the brake prior to the output of the brake control circuit when the accumulated error detection output output according to the counter value is in an ON state. An electronically controlled mechanical timepiece configured to perform the following.

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