Mechanical timepiece

Abstract

To provide a mechanical watch having improved rate accuracy.SOLUTION: The mechanical timepiece 1 includes: a balance wheel 31; a permanent magnet 41 for performing reciprocating rotational motion in association with the reciprocating rotational motion of the balance wheel 31; a coil 43 in which a counter electromotive force is generated in response to the reciprocating rotational motion of the permanent magnet 41; a detection circuit 45 for detecting a detection signal on the basis of the counter electromotive force; a reference signal source for outputting a reference signal; and rate adjustment means 40 for, when the detection timing of the detection signal is earlier than a reference timing based on the output timing of the reference signal, performing rate adjustment to delay the rate, and when the detection timing is later than the reference timing, performing rate adjustment to advance the rate.The rate adjustment means 40 determines whether or not the rotational range of the balance wheel 31 is narrower than the determined range on the basis of the counter electromotive force. If it is determined that the rotational range in current unit period of the balance wheel 31 is narrower than the determined range, rate adjustment to delay the rate in next unit period of the balance wheel 31 is not performed.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a mechanical timepiece. [Background technology]

[0002] Patent Document 1 below discloses a mechanical timepiece that generates electricity by providing a permanent magnet that rotates integrally with the balance wheel, and adjusts the rate based on the back electromotive force generated in response to the rotation of the permanent magnet. In the mechanical timepiece of Patent Document 1, if the rate is fast, control is performed to slow down the rotation, and if the rate is slow, control is performed to speed up the rotation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2023 / 176378 Summary of the Invention [Problem to be solved by the invention]

[0004] In the mechanical timepiece of Patent Document 1, if it is determined that the rate is fast when the rotation range of the balance wheel is narrowed due to the influence of external disturbances or the like, a large braking force is applied to slow the rate, but this further narrows the rotation range of the balance wheel, making it impossible to control the rate normally.

[0005] The present invention has been made in view of the above-mentioned problems, and its object is to provide a mechanical timepiece that improves rate accuracy. [Means for solving the problem]

[0006] (1) A mechanical timepiece comprising: a balance wheel that rotates in both clockwise and counterclockwise directions; a permanent magnet that rotates in both clockwise and counterclockwise directions in accordance with the clockwise and counterclockwise rotation of the balance wheel; a coil in which a back electromotive force is generated in accordance with the clockwise and counterclockwise rotation of the permanent magnet; a detection circuit that detects a detection signal based on the back electromotive force; a reference signal source that outputs a reference signal; and rate adjustment means that performs rate adjustment to delay the rate if the detection timing of the detection signal is earlier than a reference timing based on the output timing of the reference signal, and performs rate adjustment to advance the rate if the detection timing is later than the reference timing, wherein the rate adjustment means determines whether the rotation range of the balance wheel is narrower than a predetermined range based on the back electromotive force, and does not perform rate adjustment to delay the rate of the balance wheel in the next unit period if it determines that the rotation range of the balance wheel in the current unit period is narrower than the predetermined range. (2) In (1), when the rate adjustment means determines that the rotation range in the current unit period is narrower than a predetermined range, the mechanical timepiece performs rate adjustment to advance the rate of the balance wheel in the next unit period regardless of the detection timing. (3) In the mechanical timepiece of (1) or (2), the rate adjustment means determines that the rotation range of the balance wheel is narrower than the predetermined range if the number of times the back electromotive force switches between positive and negative in the current unit cycle is less than a predetermined number. (4) In the mechanical timepiece of (1) or (2), the rate adjustment means determines that the rotation range of the balance wheel is narrower than the predetermined range when the interval of the current unit period is longer than a predetermined interval. (5) In the mechanical timepiece of (1) or (2), the rate adjustment means determines whether the rotation range of the balance wheel is narrower than the predetermined range based on the interval at which the back electromotive force switches between positive and negative in the current unit cycle. (6) In any of (1) to (5), the rate adjustment means has a braking circuit that adjusts the rate by adjusting the magnitude of the braking force on the permanent magnet, and the braking circuit increases the braking force when the detection timing is ahead of the reference timing, decreases the braking force when the detection timing is behind the reference timing, and does not increase the braking force in the next unit period when it is determined that the rotation range in the current unit period is narrower than the specified range. (7) In (6), when the braking circuit determines that the rotation range in the current unit period is narrower than the specified range, the braking circuit reduces the braking force in the next unit period by a greater amount than the amount by which the braking force is reduced when the detection timing is delayed relative to the reference timing. [Effects of the Invention]

[0007] According to the above aspects (1) to (7) of the present invention, it is possible to provide a mechanical timepiece with improved rate accuracy. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is an exploded perspective view showing the base plate and the components assembled thereto. [Figure 2] FIG. 2 is a perspective view showing the escapement mechanism, the governor, and the surrounding components. [Figure 3] FIG. 1 is a block diagram showing the overall configuration of a mechanical timepiece. [Figure 4] 10A and 10B are diagrams for explaining a back electromotive force detected by a coil in accordance with rotation of a permanent magnet. [Figure 5] FIG. 4 is a diagram illustrating an example of switching of braking ranks in the present embodiment. [Figure 6] FIG. 4 is a diagram showing a process flow for rate adjustment in the present embodiment. [Figure 7] FIG. 10 is a diagram showing a process flow for rate adjustment in the first modified example. [Figure 8] FIG. 10 is a diagram showing an example of switching of braking ranks in a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention (hereinafter referred to as the present embodiment) will be described in detail with reference to the drawings.

[0010] The mechanical timepiece 1 is a timepiece that includes a power spring 11, and controls the movement of the power spring 11 with an escapement mechanism 20 and a speed regulating mechanism 30 to drive a hand 131. Power from the power spring 11 is transmitted to the escapement mechanism 20 and the speed regulating mechanism 30 through a train wheel 12. Each of these members and mechanisms is incorporated into a main plate 10.

[0011] As shown in Fig. 2, the escapement mechanism 20 includes an escape wheel 21 and an anchor 22. The escapement mechanism 20 continuously applies a force for reciprocating motion to the balance wheel 31 included in the speed regulating mechanism 30, and rotates each gear in the wheel train 12 at a constant speed by the regular vibrations from the balance wheel 31. In this embodiment, the balance wheel 31 is designed to perform one reciprocating motion every two seconds, and the escape wheel 21 is configured to perform one step motion every second.

[0012] As shown in Figures 1 and 2, the speed regulating mechanism 30 includes a balance wheel 31 and a hairspring 32. The balance wheel 31 is supported so as to be rotatable in both directions by power transmitted by the train wheel 12, with a balance arbour 311, which is the axis of rotation, as the center of rotation. The hairspring 32 is spiral-shaped, with its outer end fixed to a hairspring holder 34 (see Figure 1) and its inner end fixed to the balance arbour 311. The speed regulating mechanism 30 repeatedly rotates the balance wheel 31 in both directions (reciprocating motion) at a constant cycle by the expansion and contraction motion (elastic deformation) of the hairspring 32.

[0013] In this embodiment, the hairspring 32 is made of a resin material with a low Young's modulus. This allows the balance wheel 31 to oscillate at a slower speed than when the hairspring 32 is made of a metal material. In this embodiment, the rotation angle [deg] of the balance wheel 31 when the hairspring 32 is in a neutral position for elastic deformation is set to 0°. The neutral position for elastic deformation of the hairspring 32 is the position where the hairspring 32 is at its natural length. Power is supplied from the power spring 11 to the balance wheel 31 when the hairspring 32 is in the vicinity of the neutral position for elastic deformation.

[0014] The mechanical timepiece 1 is equipped with a rate adjustment means 40. The rate adjustment means 40 has a permanent magnet 41, a stator 42, and a coil 43 shown in Fig. 2 etc., and a control circuit 44, a detection circuit 45, a frequency divider circuit 47, an oscillation circuit 48, and a braking circuit 80 shown in Fig. 3. The rate adjustment means 40 may be any means that can realize the functions of each of these circuits.

[0015] The permanent magnet 41 is a bipolar magnetized disk-shaped rotating body, and as shown in Fig. 4, has an N-pole portion 411 and an S-pole portion 412 magnetized in the radial direction to N-pole and S-pole. An insertion hole through which the balance stem 311 is inserted is formed in the center of the permanent magnet 41. The permanent magnet 41 rotates forward and backward together with the balance wheel 31 so that the rotation angle of the permanent magnet 41 is the same as the rotation angle of the balance wheel 31 in accordance with the forward and reverse rotation of the balance wheel 31 (balance stem 311).

[0016] The stator 42 is made of a soft magnetic material and includes a first magnetic portion 421 having a first end 421a and a second magnetic portion 422 having a second end 422a, and forms a magnetic circuit together with the coil 43. The stator 42 is provided so that a magnetic torque is generated with respect to the permanent magnet 41 in accordance with the rotation angle of the permanent magnet 41.

[0017] The control circuit 44 controls the operation of each circuit included in the rate adjusting means 40. The control circuit 44 can perform braking control, which controls the braking force that brakes the permanent magnet 41, by controlling the braking circuit 80. The braking force can be applied to the permanent magnet 41, for example, based on an electromagnetic brake. Note that the electromagnetic brake is a closed-loop state created by short-circuiting the first and second terminals of the coil 43, and can generate a braking force by induced electromotive force that generates a magnetic field in a direction that obstructs changes in the magnetic flux generated in the coil 43 as the permanent magnet 41 rotates.

[0018] The detection circuit 45 detects the detection signal DE based on the voltage waveform generated in the coil 43 due to the motion of the permanent magnet 41. The detection signal DE detected by the detection circuit 45 is input to the control circuit 44. In this embodiment, the detection signal DE is a pulse signal synchronized with the timing when the back electromotive force switches from negative to positive and is detected by the detection circuit 45 when a back electromotive force equal to or greater than a predetermined threshold Vth occurs. The detection signal, which indicates the start timing of a unit cycle, may be determined by setting a non-determination period during which the zero-crossing point where the back electromotive force switches from negative to positive is not determined to be a detection signal. The predetermined threshold Vth may be a value near 0 [V], for example, +10 [mV]. The detection signal DE is a pulse signal synchronized with the timing when the back electromotive force switches from positive to negative and may be detected by the detection circuit 45 when a back electromotive force equal to or less than a predetermined threshold -Vth occurs. Note that noise may momentarily occur near the threshold Vth of 0 [V] due to external factors such as impact. In order to avoid erroneous detection due to such noise, etc., the timing for determining the detection signal DE for rotation detection may be set to any timing when the detection signal DE is detected consecutively a predetermined number of times (for example, the timing when it was last detected).

[0019] The oscillator circuit 48 outputs a predetermined oscillation signal based on the frequency of the quartz crystal oscillator 70. The frequency divider circuit 47 divides the frequency of the oscillation signal output from the oscillator circuit 48. In this embodiment, the frequency divider circuit 47 divides the frequency of the oscillation signal based on the quartz crystal oscillator 70 to generate a reference signal OS that is output at intervals corresponding to the unit period of the speed regulating mechanism 30. The output timing of the reference signal OS is set in advance so as to correspond to the detection signal DE when the forward and reverse rotational motion of the balance wheel 31 is normal, and in this embodiment, the reference signal OS is output approximately every 500 ms.

[0020] The mechanical timepiece 1 has a power generation function that uses the principle of electromagnetic induction. In this embodiment, the permanent magnet 41 rotates forward and backward as the balance wheel 31 rotates forward and backward, and electricity is generated by the current generated in the coil 43 based on the change in the magnetic field caused by the movement of the permanent magnet 41, with the regulating mechanism 30 functioning as part of a generator. The power extracted by this power generation function is used to start the power supply circuit 60. When the power supply circuit 60 is started, the control circuit 44 can be driven.

[0021] Rectifier circuit 50 rectifies the current generated in coil 43 due to the movement of permanent magnet 41 accompanying the forward and reverse rotation of balance wheel 31 of speed regulating mechanism 30. Power supply circuit 60 includes, for example, a capacitor, and stores power for driving control circuit 44 based on the current rectified by rectifier circuit 50.

[0022] 4, the relationship between the rotation angle of permanent magnet 41 and the back electromotive force will be described, with reference to the back electromotive force detected by coil 43 as permanent magnet 41 rotates in the forward direction (clockwise in FIG. 4) from the 0° position, rotates in the reverse direction (counterclockwise in FIG. 4) due to the elastic force of hairspring 32, and then rotates again in the forward direction due to the elastic force of hairspring 32. In FIG. 4, an example is shown in which the oscillation angle of balance wheel 31 is preset to ±340°, and the period from when permanent magnet 41 moves from a rotation angle of 0° to the maximum positive angle (+340°) and returns to 0°, and the period from when rotation angle 0° to when it moves from the maximum negative angle (-340°) and returns to 0° are defined as a "unit period."

[0023] The counter electromotive force generated in the coil 43 due to a change in the magnetic field when the N-pole portion 411 of the permanent magnet 41 moves in a direction toward the first end 421a of the stator 42 is defined as a "positive" counter electromotive force. The counter electromotive force generated in the coil 43 due to a change in the magnetic field when the N-pole portion 411 moves in a direction away from the first end 421a of the stator 42 is defined as a "negative" counter electromotive force.

[0024] At the 0° position, the permanent magnet 41 is in a position of magnetic balance, and the back electromotive force generated in the coil 43 is zero. At the 0° position, the permanent magnet 41 is supplied with power from the power spring 11. Furthermore, while the permanent magnet 41 rotates from the 0° position toward the 180° position, the N pole portion 411 moves in a direction approaching the first end 421a. Therefore, while the permanent magnet 41 rotates from the 0° position toward the 180° position, a positive back electromotive force is generated in the coil 43.

[0025] Since the permanent magnet 41 is in a position of magnetic balance at the 0° position, it is also in a position of magnetic balance at the 180° position, and the back electromotive force generated in the coil 43 is zero. When the permanent magnet 41 rotates from the 180° position toward the 340° position, the N pole portion 411 moves in a direction away from the first end 421a. Therefore, a negative back electromotive force is generated in the coil 43 while the permanent magnet 41 rotates from the 180° position toward the 340° position.

[0026] The angular velocity of the permanent magnet 41 becomes zero at the 340° position, which is the turning point of the reciprocating motion. Therefore, the back electromotive force generated in the coil 43 becomes zero at the 340° position. When the permanent magnet 41 reaches the 340° position, the elastic force of the hairspring 32 causes the permanent magnet 41 to start rotating in the reverse direction. When the permanent magnet 41 rotates from the 340° position toward the 180° position, the N-pole portion 411 moves in a direction approaching the first end 421a. Therefore, a positive back electromotive force is generated in the coil 43 while the permanent magnet 41 rotates from the 340° position toward the 180° position.

[0027] When the permanent magnet 41 rotates from the 180° position to the 0° position, the N-pole portion 411 moves in a direction away from the first end 421a. Therefore, when the permanent magnet 41 rotates from the 180° position to the 0° position, a negative counter electromotive force is generated in the coil 43.

[0028] Power is supplied from the power spring 11 to the permanent magnet 41 that has reached the 0° position. While the permanent magnet 41 rotates from the 0° position toward the −180° position, the N-pole portion 411 moves in a direction approaching the first end 421a. Therefore, when the permanent magnet 41 rotates from the 0° position toward the −180° position, a positive counter electromotive force is generated in the coil 43.

[0029] Just as the permanent magnet 41 is in a magnetically balanced position at the 180° position, it is also in a magnetically balanced position at the −180° position, and the back electromotive force generated in the coil 43 is zero when the permanent magnet 41 is in the −180° position. When the permanent magnet 41 rotates from the −180° position to the −340° position, the N pole portion 411 moves in a direction away from the first end 421a. Therefore, a negative back electromotive force is generated in the coil 43 while the permanent magnet 41 rotates from the −180° position to the −340° position.

[0030] The angular velocity of the permanent magnet becomes zero at the -340° position, which is the turning point of the reciprocating motion. Therefore, the back electromotive force generated in the coil 43 becomes zero at the -340° position. When the permanent magnet 41 reaches the -340° position, the elastic force of the hairspring 32 causes the permanent magnet 41 to start rotating in the forward direction. When the permanent magnet 41 rotates from the -340° position toward the -180° position, the N-pole portion 411 moves in a direction approaching the first end 421a. Therefore, a positive back electromotive force is generated in the coil 43 while the permanent magnet 41 rotates from the -340° position toward the -180° position.

[0031] When the permanent magnet 41 rotates from the -180° position to the 0° position, the N-pole portion 411 moves in a direction away from the first end 421a. Therefore, when the permanent magnet 41 rotates from the -180° position to the 0° position, a negative counter electromotive force is generated in the coil 43.

[0032] When the above-described operation is repeated and the balance wheel 31 (permanent magnet 41) normally rotates in both directions, a back electromotive force shown in FIG.

[0033] In this embodiment, the braking rank is changed based on the difference between the output timing of the reference signal OS and the detection timing of the detection signal DE. If the period difference t calculated by subtracting the detection timing of the detection signal DE from the output timing of the reference signal OS is greater than 0, the brake is "leading" and the braking rank by the electromagnetic brake DB is increased to slow the rate. If the period difference t is 0 or less, the brake is "lagging" and the braking rank by the electromagnetic brake DB is decreased to speed up the rate. The electromagnetic brake outputs multiple consecutive single pulses, and the strength of the braking force can be changed by adjusting the length of the single pulses and the output interval between the single pulses, or the so-called duty ratio.

[0034] In this embodiment, the rate adjustment means 40 is provided with a judgment unit 44a, which judges whether or not the rotation range of the balance wheel 31 is narrower than a predetermined range based on the back electromotive force, and if it is judged that the rotation range of the balance wheel 31 in the current unit period is narrower than the predetermined range (the rotation range is within the predetermined range), the braking rank of the balance wheel 31 in the next unit period is lowered regardless of the detection timing of the detection signal DE.

[0035] 5 shows an example in which the rotation of the balance wheel 31 is disturbed in the second unit period, causing the absolute value of the rotation range of the balance wheel 31 to fall below 180°, and the balance wheel 31 operates normally in other unit periods. In FIG. 5, an example is shown in which the rotation range of the balance wheel 31 when operating normally is set to -270° to +270°, and the relationship between the rotation angle of the balance wheel 31 operating normally and the back electromotive force is the same as the example described with reference to FIG. 4.

[0036] First, the power supply circuit 60 is activated by power generation due to the movement of the permanent magnet 41 (Y at S1 in FIG. 6). After that, the detection signal DE is detected (Y at S2 in FIG. 6), and the zero-crossing points are counted until the next detection signal DE is detected (S3, S4 in FIG. 6). When the next detection signal DE is detected, the time difference t between the detection timing and the output timing of the reference signal OS is calculated (S5 in FIG. 6).

[0037] If the number of zero crossing points until the next detection signal DE is detected is three, the judgment unit 44a judges that the rotation range of the balance wheel 31 in the current unit period is not within the predetermined range (N in S6 in Figure 6), and if the number of zero crossing points is less than three, it judges that the rotation range of the balance wheel 31 in the current unit period is within the predetermined range (Y in S6 in Figure 6).

[0038] 5, there are three zero-crossing points between the detection timing of the detection signal DE, which is the start timing of the first unit cycle, and the detection timing of the detection signal DE, which is the start timing of the second unit cycle, so the determination unit 44a determines that the rotation range of the balance wheel 31 is not within a predetermined range (N at S6 in FIG. 6), and because the detection timing of the detection signal DE, which is the start timing of the second unit cycle, is earlier than the output timing of the reference signal OS (N at S7 in FIG. 6), the braking rank is switched from braking rank 11 in the first unit cycle to braking rank 12 in the second unit cycle to slow the rate (S9 in FIG. 6). If the detection timing of the detection signal DE, which is the start timing of the unit cycle, is later than the output timing of the reference signal OS (Y at S7 in FIG. 6), it is advisable to lower the braking rank by one rank (S8 in FIG. 6).

[0039] 5, since there is one zero-crossing point between the detection timing of the detection signal DE, which is the start timing of the second unit cycle, and the detection timing of the detection signal DE, which is the start timing of the third unit cycle, the determination unit 44a determines that the rotation range of the balance wheel 31 is within a predetermined range (Y at S6 in FIG. 6), and switches the braking rank from braking rank 12 in the second unit cycle to braking rank 9 in the third unit cycle (S10 in FIG. 6). In this way, in order to make it easier to return to control at a normal rotation angle, when the determination unit 44a determines that the rotation range of the balance wheel 31 in the current unit cycle is within a predetermined range, the braking force is reduced by a greater amount than would be the case if the detection timing of the detection signal DE was delayed relative to the output timing of the reference signal OS.

[0040] As shown in the flowchart of Fig. 7, the determination of whether the rotation range of the balance wheel 31 is within a predetermined range and the subsequent switching of the braking rank may be performed only when the rate is fast (N in S16, S17 to S19). When the rate is slow (Y in S16), the braking rank is lowered (S20) although the amount of reduction is small, so that deviation of the rate can be further suppressed even when normal operation is not being performed due to the influence of external disturbances, etc.

[0041] 8 shows an example in which the determination unit 44a determines whether the rotation range of the balance wheel 31 in the current unit period is within a predetermined range based on whether the detection intervals T1, T2, T3 of the detection signal DE are equal to or greater than a predetermined time T0. If the detection intervals T1, T2, T3 of the detection signal DE are equal to or greater than the predetermined time T0, the determination unit 44a determines that the rotation range of the balance wheel 31 in the current unit period is within the predetermined range, and if the detection intervals T1, T2, T3 of the detection signal DE are shorter than the predetermined time T0, the determination unit 44a determines that the rotation range of the balance wheel 31 in the current unit period is not within the predetermined range. The predetermined time T0 is the elapsed time from the start timing of the unit period, and its length is the same for all unit periods.

[0042] In the first unit cycle, the detection interval T1 is shorter than the predetermined length T0, so the balance wheel 31 operates normally. Also, the detection timing of the detection signal DE, which corresponds to the start timing of the second unit cycle, is earlier than the output timing of the reference signal OS, so the braking rank is switched from braking rank 11 in the first unit cycle to braking rank 12 in the second unit cycle in order to slow down the rate.

[0043] In the second unit cycle, the detection interval T2 is equal to or greater than the predetermined length T0, so the rotation of the balance wheel 31 is disturbed, and no rate adjustment is made to slow the rate in the third unit cycle, regardless of whether the detection signal DE corresponding to the start timing of the third unit cycle is early or late. In the example shown in Figure 8, the braking rank is switched from braking rank 12 in the second unit cycle to braking rank 9 in the third unit cycle.

[0044] In the third unit cycle, the detection interval T3 is shorter than the predetermined length T0, so the balance wheel 31 operates normally. In the subsequent unit cycles, the detection signal DE is earlier than the reference signal OS, so rate adjustment is performed to increase the braking rank.

[0045] The rotation range of the balance wheel 31 may be determined by other methods. For example, the determination unit 44a may determine the rotation range of the balance wheel 31 based on the interval at which the back electromotive force switches between positive and negative in a unit period. Specifically, the determination unit 44a may determine the rotation range of the balance wheel 31 based on the interval between the first and second zero crossing points or the interval between the first and third zero crossing points in a unit period. In this case, it is preferable that the reference signal OS is set to be output in correspondence with each zero crossing point.

[0046] The braking rank may be lowered by three ranks after it has been determined consecutively that the rotation range of the balance wheel 31 is within the predetermined range, and before lowering the braking rank by three ranks, the braking rank may be increased or decreased by one rank by normal braking control (S7 to S9 in FIG. 6) every time the detection signal DE is detected, or the braking rank may not be changed. The number of consecutive times may be three or more.

[0047] The amount by which the braking rank is decreased when the determining unit 44a determines that the rotation range of the balance wheel 31 is narrower than the predetermined range may be the same as the amount by which the braking rank is increased or decreased when the determining unit 44a determines that the rotation range of the balance wheel 31 is equal to or greater than the predetermined range, as long as the braking rank is not increased. The amount by which the braking rank is changed may be changed depending on the magnitude of the period difference t.

[0048] According to this embodiment, when an external disturbance occurs and disrupts the waveform of the back electromotive force, causing the rotation range of the balance wheel 31 to become narrower than the predetermined range, a large braking force is not applied to slow the rate, preventing the rotation range from becoming even narrower, and normal rate control is possible.

[0049] The braking rank may be switched depending on whether the detection timing of the detection signal DE is earlier or later than the reference timing based on the output timing of the reference signal OS. Any configuration may be used as long as the braking circuit 80 is capable of performing braking control (rate adjustment), and the braking force may be adjusted by a speed control pulse. [Explanation of symbols]

[0050] 1 mechanical watch, 10 main plate, 11 power spring, 12 wheel train, 131 hands, 20 escapement mechanism, 21 escape wheel, 22 anchor, 30 regulating mechanism, 31 balance wheel, 311 balance stem, 32 hairspring, 34 hairspring holder, 40 rate adjusting means, 41 permanent magnet, 42 stator, 421 first magnetic part, 421a first end, 422 second magnetic part, 422a second end, 43 coil, 44 control circuit, 44a judgment part, 45 detection circuit, 47 frequency divider circuit, 48 oscillation circuit, 50 rectifier circuit, 60 power supply circuit, 70 quartz oscillator, 80 braking circuit.

Claims

1. A balance wheel that rotates forward and backward, a permanent magnet that rotates in a forward and reverse direction in accordance with the forward and reverse rotation of the balance wheel; a coil in which a counter electromotive force is generated in response to the forward and reverse rotational motion of the permanent magnet; a detection circuit that detects a detection signal based on the back electromotive force; a reference signal source that outputs a reference signal; a rate adjusting means for adjusting the rate to delay the rate if the detection timing of the detection signal is earlier than a reference timing based on the output timing of the reference signal, and for adjusting the rate to advance the rate if the detection timing is later than the reference timing; and the rate adjustment means determines whether or not a rotation range of the balance wheel is narrower than a predetermined range based on the back electromotive force, and when it determines that the rotation range of the balance wheel in the current unit period is narrower than the predetermined range, does not perform rate adjustment to slow down the rate of the balance wheel in the next unit period. Mechanical watch.

2. when it is determined that the rotation range in the current unit period is narrower than a predetermined range, the rate adjustment means performs a rate adjustment to advance the rate of the balance wheel in the next unit period regardless of the detection timing.

2. The mechanical timepiece according to claim 1.

3. the rate adjustment means determines that the rotation range of the balance wheel is narrower than the predetermined range when the number of times that the back electromotive force switches between positive and negative in the current unit period is less than a predetermined number of times; 2. The mechanical timepiece according to claim 1.

4. When the interval of the current unit period is longer than a predetermined interval, the rate adjustment means determines that the rotation range of the balance wheel is narrower than the predetermined range.

2. The mechanical timepiece according to claim 1.

5. the rate adjustment means determines whether or not the rotation range of the balance wheel is narrower than the predetermined range based on the interval at which the back electromotive force switches between positive and negative in the current unit cycle.

2. The mechanical timepiece according to claim 1.

6. the rate adjusting means has a braking circuit that adjusts the rate by adjusting the magnitude of the braking force applied to the permanent magnet, The braking circuit comprises: When the detection timing is ahead of the reference timing, the braking force is increased, and when the detection timing is behind the reference timing, the braking force is decreased. When it is determined that the rotation range in the current unit period is narrower than the predetermined range, the braking force in the next unit period is not increased. The mechanical timepiece according to any one of claims 1 to 5.

7. when it is determined that the rotation range in the current unit period is narrower than the predetermined range, the braking circuit reduces the braking force in the next unit period by a larger amount than the amount of reduction when the braking force is reduced in a case where the detection timing is delayed with respect to the reference timing; 7. The mechanical timepiece according to claim 6.

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