Mechanical timepiece

Abstract

To provide a mechanical timepiece for improving rate accuracy.SOLUTION: A mechanical timepiece 1 includes a speed control mechanism 30 including a rotating body that performs forward and reverse rotational motion, a permanent magnet 41 that performs forward and reverse rotational motion along with the forward and reverse rotational motion of the rotating body, a coil 43 in which a counter electromotive voltage is generated according to the forward and reverse rotational motion of the permanent magnet 41, and a detection circuit 45 that detects a detection signal based on the counter electromotive voltage. And a rate adjustment means 40 for performing rate adjustment by switching a braking force for braking the permanent magnet 41 between a first braking force and a second braking force larger than the first braking force, wherein the rate adjustment means 40 brakes the permanent magnet 41 with a third braking force larger than the first braking force and smaller than the second braking force in a transition period when switching the braking force between the first braking force and the second braking force.SELECTED DRAWING: Figure 6

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] The inventors of the present invention have been studying how to adjust the rate of a mechanical timepiece with adjustable rate with greater accuracy.

[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 speed-regulating mechanism including a rotating body that rotates in both directions; a permanent magnet that rotates in both directions in accordance with the rotating body's rotation; a coil that generates a back electromotive force in response to the rotation of the permanent magnet; a detection circuit that detects a detection signal based on the back electromotive force; and rate adjustment means that adjusts the rate by switching the braking force that brakes the permanent magnet between a first braking force and a second braking force that is greater than the first braking force based on the detection timing of the detection signal, wherein the rate adjustment means brakes the permanent magnet with a third braking force that is greater than the first braking force and less than the second braking force during a transition period when the braking force is switched between the first braking force and the second braking force.

[0007] (2) In (1), the rate adjustment means switches from the third braking force to the first braking force after the detection timing of the detection signal detected during the transition period when switching from the first braking force to the second braking force if the detection timing of the detection signal detected during the transition period when switching from the first braking force to the second braking force is delayed relative to the reference timing, and switches from the third braking force to the second braking force after the detection timing if the detection timing of the detection signal detected during the transition period when switching from the second braking force to the first braking force is advanced relative to the reference timing.

[0008] (3) In (1), the rate adjustment means continues braking the permanent magnet with the first braking force if the detection timing of the detection signal detected when braking the permanent magnet with the first braking force is delayed relative to the reference timing, and switches from the first braking force to the third braking force after the detection timing if the detection timing of the detection signal detected when braking the permanent magnet with the first braking force is advanced relative to the reference timing.

[0009] (4) In the mechanical timepiece of (1) or (2), the rate adjustment means continues braking the permanent magnet with the first braking force if the detection timing of the detection signal detected when braking the permanent magnet with the first braking force is delayed relative to the reference timing, and switches from the first braking force to the third braking force after the detection timing if the detection timing of the detection signal detected when braking the permanent magnet with the first braking force is advanced relative to the reference timing.

[0010] (5) In (4), the rate adjustment means continues braking the permanent magnet with the second braking force if the detection timing of the detection signal detected when braking the permanent magnet with the second braking force is ahead of the reference timing, and switches from the second braking force to the third braking force after the detection timing if the detection timing of the detection signal detected when braking the permanent magnet with the second braking force is behind the reference timing.

[0011] (6) The mechanical timepiece according to any one of (1) to (5), wherein the rate adjusting means changes the magnitude of the third braking force during the transition period.

[0012] (7) In (6), the rate adjustment means gradually increases the third braking force during the transition period when switching from the first braking force to the second braking force, and gradually decreases the third braking force during the transition period when switching from the second braking force to the first braking force.

[0013] (8) In any one of (1) to (7), the mechanical timepiece sets the magnitude of the third braking force based on the detection timing of the detection signal detected immediately before the transition period. [Effects of the Invention]

[0014] According to the above aspects (1) to (8) of the present invention, it is possible to provide a mechanical timepiece with improved rate accuracy. [Brief explanation of the drawings]

[0015] [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 the braking force of an electromagnetic brake. [Figure 6] FIG. 2 is a diagram illustrating control in the present embodiment. [Figure 7] 4 is a flowchart showing a control according to the present embodiment. [Figure 8] 10 is a flowchart showing control in a modified example of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention (hereinafter referred to as the present embodiment) will be described in detail with reference to the drawings.

[0017] The overall configuration of a mechanical timepiece 1 will be described with reference to Figures 1 to 4. As shown in Figure 2, the mechanical timepiece 1 is equipped with a power spring 11, an escapement mechanism 20, a speed regulating mechanism 30, and hands 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.

[0018] The escapement mechanism 20 continuously applies a force for reciprocating motion to the balance wheel 31 included in the regulating mechanism 30, and rotates each gear in the wheel train 12 at a constant speed by regular vibrations from the balance wheel 31. As shown in FIG. 2, the escapement mechanism 20 includes an escape wheel 21 and an anchor 22. 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.

[0019] 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 forward and reverse directions around a balance arbour 311, which is a rotation axis.

[0020] The hairspring 32 is spiral-shaped, and its outer end is fixed to a hairspring holder 34 (see FIG. 1), and its inner end is fixed to a balance arbour 311. The speed-governing mechanism 30 uses the expansion and contraction movement (elastic deformation) of the hairspring 32 to repeatedly rotate the balance wheel 31 forward and backward (reciprocating motion) at a constant cycle.

[0021] 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 vibrate at a slower speed than when the hairspring 32 is made of a metal material. Also, in this embodiment, the rotation angle [deg] of the balance wheel 31 when the hairspring 32 is in a neutral position (natural length position) of elastic deformation is set to 0°. Power is supplied from the power spring 11 to the balance wheel 31 when the hairspring 32 is in a state near the neutral position of elastic deformation. In other words, the 0° position is the power supply position.

[0022] Furthermore, 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.

[0023] 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).

[0024] 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.

[0025] The control circuit 44 controls the operation of each circuit included in the rate adjusting means 40. The control circuit 44 sets the braking force for braking the permanent magnet 41 by controlling the braking circuit 80. The braking force is applied to the permanent magnet 41, for example, by an electromagnetic brake. The electromagnetic brake is preferably an induced electromotive force that generates a magnetic field in a direction that prevents a change in the magnetic flux generated in the coil 43 as the permanent magnet 41 rotates by short-circuiting the first and second terminals of the coil 43 to create a closed loop.

[0026] The detection circuit 45 detects the detection signal DE based on the voltage waveform generated in the coil 43 due to the movement of the permanent magnet 41. The detection signal DE detected by the detection circuit 45 is input to the control circuit 44. The detection signal DE may be detected by the detection circuit 45 when a back electromotive force equal to or greater than a predetermined threshold Vth is generated. In this embodiment, the detection signal DE is a pulse signal synchronized with the start timing of a unit cycle of the back electromotive force. Here, the start timing of the unit cycle is the timing when the balance wheel 31 passes the 0° position, which corresponds to the zero-crossing point where the back electromotive force switches from negative to positive. The detection signal that is the start timing of the unit cycle may be determined, for example, by setting a non-determination period during which a zero-crossing point other than the start timing of the unit cycle where the back electromotive force switches from negative to positive is not determined to be a detection signal.

[0027] The predetermined threshold Vth is preferably a value near 0 [V], for example, +10 [mV]. Note that noise may momentarily occur near the threshold Vth of 0 [V] due to external factors such as impact. To avoid false detection due to such noise, for example, the timing for determining the detection signal DE for rotation detection may be set to any timing when the detection signal DE is detected two or more times in succession (for example, the timing when it was last detected). Furthermore, 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 less than the predetermined threshold -Vth occurs.

[0028] The oscillator circuit 48 outputs a predetermined oscillation signal based on the frequency of the crystal oscillator 70. The frequency divider circuit 47 divides the oscillation signal output from the oscillator circuit 48. By dividing the oscillation signal based on the crystal oscillator 70, the frequency divider circuit 47 generates a reference signal OS that is output at intervals corresponding to the unit period of the back electromotive force. The output timing of the reference signal OS is set in advance so as to correspond to the detection signal DE that is detected when there is neither an advance nor a delay in the forward or reverse rotational motion of the balance wheel 31. In this embodiment, the reference signal OS is output approximately every 500 ms.

[0029] The mechanical timepiece 1 has a power generation function that uses the principle of electromagnetic induction. In this embodiment, the regulating mechanism 30 functions as part of the generator. Specifically, the permanent magnet 41 rotates forward and backward as the balance wheel 31 rotates forward and backward, and electricity is generated by the current that is generated in the coil 43 based on the change in the magnetic field caused by the movement of the permanent magnet 41. The power extracted using this operating principle is used to start the power supply circuit 60. When the power supply circuit 60 is started, the control circuit 44 can be driven.

[0030] 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.

[0031] 3 is an example, and is not limited to the configuration shown in the figure as long as it can realize the above-mentioned functions. Also, as long as it is configured to enable braking control (rate adjustment), it is not limited to an electromagnetic brake, and for example, braking of the permanent magnet 41 may be performed by a speed control pulse.

[0032] The relationship between the rotation angle of the permanent magnet 41 and the back electromotive force will be described with reference to Fig. 4. Here, an example will be described in which the swing angle (maximum angle) of the balance wheel 31 is preset to ±340°.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] The angular velocity of the permanent magnet 41 becomes zero at the 340° position, which is the turning point of the reciprocating motion. Therefore, at the 340° position, the back electromotive force generated in the coil 43 becomes zero. When the permanent magnet 41 reaches the 340° position, the elastic force of the hairspring 32 causes the permanent magnet 41 to start rotating toward the 180° position. 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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 toward the −180° position. 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.

[0041] 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.

[0042] The above-described operation is repeated, and when there is neither advance nor delay in the forward or reverse rotational motion of the balance wheel 31 (permanent magnet 41), a back electromotive force shown in FIG.

[0043] Next, the control by the control circuit 44 in this embodiment will be described in detail with reference to FIGS.

[0044] The control circuit 44 adjusts the rate by changing the braking force applied to the permanent magnet 41 based on the difference between the output timing of the reference signal OS and the detection timing of the detection signal DE. When the difference t calculated by subtracting the detection timing of the detection signal DE from the output timing of the reference signal OS is equal to or greater than 0, the control circuit 44 determines that the rate is "leading" and sets the electromagnetic brake DB to a large braking force to slow the rate. When the difference t is less than 0, the control circuit 44 determines that the rate is "leading" and sets the electromagnetic brake DB to a small braking force to speed up the rate.

[0045] FIG. 5 shows the electromagnetic brakes DB associated with the first braking force, the second braking force, and the third braking force. The electromagnetic brakes DB are output in the form of a single pulse, and the strength of the braking force can be changed by adjusting the length of the single pulse and the output interval of the single pulse. In this embodiment, the braking force is set based on a duty ratio. The duty ratio is the proportion of the application period Tb during which the electromagnetic brake DB is applied to a predetermined period Ta. The period Ta and the application period Tb may be set arbitrarily, but it is desirable to set them to a resolution that allows changes in the back electromotive force to be captured, for example, Ta = 0.5 ms or so.

[0046] In this embodiment, the second braking force is greater than the first braking force. The third braking force is greater than the first braking force but smaller than the second braking force. That is, the second braking force has a higher duty ratio than the first braking force, and the third braking force has a higher duty ratio than the first braking force but smaller than the second braking force. Specifically, as shown in FIG. 5, the duty ratio of the first braking force is 4 / 16 (the proportion of the application period Tb in the predetermined period Ta is 25%). The duty ratio of the second braking force is 12 / 16 (the proportion of the application period Tb in the predetermined period Ta is 75%). The duty ratio of the third braking force is 8 / 16 (the proportion of the application period Tb in the predetermined period Ta is 50%). However, the duty ratio is not limited to this, and it is preferable that the duty ratio of each braking force be in the range of 0% to 100%.

[0047] 5 shows an example in which the electromagnetic brake DB is activated not simultaneously with the detection of the detection signal DE but after a time ts has elapsed since the detection. This is because the electromagnetic brake DB is turned off when the back electromotive force is at its highest, thereby enabling effective power generation based on the back electromotive force. However, this is not a limitation, and the activation timing of the electromagnetic brake DB can be any timing, and the time ts may be approximately 0.

[0048] In this embodiment, the permanent magnet 41 is first braked by the first braking force. Then, if the detection timing of the detection signal DE is delayed relative to the output timing of the reference signal OS, braking of the permanent magnet 41 by the first braking force is continued to advance the rate. In Fig. 6, the detection timings of the detection signals DE1 and DE2 are both delayed relative to the output timing of the reference signal OS, so braking by the first braking force is continued even in the unit cycle after the detection of the detection signal DE2.

[0049] If the detection timing of the detection signal DE is ahead of the output timing of the reference signal OS, the braking force may be switched from the first braking force to the second braking force in order to slow down the pace.

[0050] Here, if the braking force is switched from the first to the second braking force immediately, the force applied to the permanent magnet 41 will change suddenly, which may cause the movement of the permanent magnet 41 to become unstable. For this reason, in this embodiment, a configuration is adopted that suppresses a sudden change in the braking force that brakes the permanent magnet 41. Specifically, rather than switching from the first braking force to the second braking force immediately, the permanent magnet 41 is braked by a third braking force, which is an intermediate braking force, during the transition period when switching from the first braking force to the second braking force. Similarly, the permanent magnet 41 is braked by the third braking force during the transition period when switching from the second braking force to the first braking force.

[0051] 6 shows an example in which the detection timing of the detection signal DE3 is advanced relative to the output timing of the reference signal OS, and therefore the first braking force is switched to the second braking force to slow down the rate. Also, the unit cycle after the detection of the detection signal DE3 is a transition period, and the permanent magnet 41 is braked by the third braking force during this transition period. Also, the example shows an example in which the third braking force is switched to the second braking force after the detection signal DE4 is detected, regardless of the detection timing of the detection signal DE4 detected during the transition period.

[0052] 6 also shows an example in which braking with the second braking force continues in the next unit cycle because the detection timing of the detection signal DE5 is advanced relative to the output timing of the reference signal OS. Furthermore, an example in which the detection timing of the detection signal DE6 is delayed relative to the output timing of the reference signal OS, so the second braking force is switched to the first braking force to advance the rate. Also, an example in which the unit cycle after the detection of the detection signal DE6 is a transition period, during which the permanent magnet 41 is braked with the third braking force, is shown. After this, regardless of the detection timing of the detection signal DE7 detected during the transition period, the third braking force may be switched to the first braking force after the detection signal DE7 is detected.

[0053] Next, a control process flow by the control circuit 44 in this embodiment will be described with reference to Fig. 7. First, the power supply circuit 60 is started up as a result of power generation caused by the movement of the permanent magnet 41 (Y in S1). After the first detection signal DE is detected by the detection circuit 45 (Y in S2), the control circuit 44 sets the braking force to the first braking force and brakes the permanent magnet 41 with the first braking force (S3). Note that the braking force after the first detection signal DE is detected may be set to either the first braking force or the second braking force.

[0054] When the next detection signal DE is detected (Y in S4), the control circuit 44 calculates the deviation amount t of the detection signal DE (S5). When the deviation amount t is smaller than 0 (N in S6), the control circuit 44 continues the state in which the braking force is set to the first braking force (S3).

[0055] If the deviation amount t is equal to or greater than 0 (Y in S6), the control circuit 44 sets the braking force to the third braking force and brakes the permanent magnet 41 with the third braking force (S7). If the detection signal DE is further detected (Y in S8), regardless of the detection timing, the control circuit 44 sets the braking force to the second braking force and brakes the permanent magnet 41 with the second braking force (S9).

[0056] When the next detection signal DE is detected (Y in S10), the control circuit 44 calculates the deviation amount t of the detection signal DE (S11). When the deviation amount t is greater than 0 (N in S12), the control circuit 44 continues the state in which the braking force is set to the second braking force (S9).

[0057] If the deviation amount t is equal to or less than 0 (Y in S12), the control circuit 44 sets the braking force to the third braking force and brakes the permanent magnet 41 with the third braking force (S13). Furthermore, if the detection signal DE is detected (Y in S14), regardless of the detection timing, the control circuit 44 sets the braking force to the first braking force and brakes the permanent magnet 41 with the first braking force (S3).

[0058] In the mechanical timepiece 1 according to the present embodiment described above, the movement of the permanent magnet 41 and the balance wheel 31 can be stabilized by suppressing sudden changes in the braking force. As a result, the rate accuracy can be improved. Furthermore, suppressing sudden changes in the braking force smooths the movement of the balance wheel 31, which is expected to attract the user's attention. In this case, the balance wheel 31 is preferably arranged to be visible through the dial. The dial may include a transparent portion that allows part or all of the balance wheel 31 to be visible from the outside. Alternatively, the dial may have an opening that allows part or all of the balance wheel 31 to be visible from the outside. The dial is a plate on which the hour digits indicated by the hands are arranged.

[0059] Next, a process flow of control by the control circuit 44 in a modified example of this embodiment will be described with reference to Fig. 8. The same processes as those shown in Fig. 7 are designated by the same reference numerals, and descriptions thereof will be omitted where appropriate.

[0060] In this modified example, if the advance or delay of the detection signal DE detected during the transition period is reversed from the detection timing of the detection signal detected last time, the braking force is not switched as scheduled but is returned to the original braking force. Specifically, if the detection signal DE is delayed during the transition period when switching from the first braking force to the second braking force, the braking force is returned to the first braking force to prevent the rate from becoming further delayed. Also, if the detection signal DE is advanced during the transition period when switching from the second braking force to the first braking force, the braking force is returned to the second braking force to prevent the rate from becoming further advanced.

[0061] As shown in FIG. 8, the control circuit 44 performs the processes S1 to S6 described in FIG. 7. If the deviation t is equal to or greater than 0 (Y in S6), the control circuit 44 sets the braking force to the third braking force and brakes the permanent magnet 41 with the third braking force (S7). If the detection signal DE is detected during this transition period (Y in S8), the control circuit 44 calculates the deviation t of the detection signal DE (S21). Then, if the deviation t is equal to or less than 0 (Y in S22), the control circuit 44 sets the braking force to the first braking force (S3). In other words, if the detected detection signal DE is delayed during the transition period when switching from the first braking force to the second braking force, the control circuit 44 temporarily reduces the braking force rather than increasing it as originally planned. This prevents the detection signal DE from being further delayed.

[0062] On the other hand, if the deviation amount t is greater than 0 (N in S22), the control circuit 44 sets the braking force to the second braking force as originally planned and brakes the permanent magnet 41 with the second braking force (S9). Then, the control circuit 44 performs the processes of S10 to S12 described in FIG. 7, and if the deviation amount t is equal to or less than 0 (Y in S12), sets the braking force to the third braking force and brakes the permanent magnet 41 with the third braking force (S13). If the detection signal DE is detected during this transition period (Y in S14), the control circuit 44 calculates the deviation amount t of the detection signal DE (S23). Then, if the deviation amount t is equal to or greater than 0 (Y in S24), the control circuit 44 sets the braking force to the second braking force (S3). That is, if the detection signal DE detected during the transition period when switching from the second braking force to the first braking force is advanced, the braking force is temporarily increased rather than decreased as originally planned. This prevents the detection signal DE from being further advanced.

[0063] On the other hand, if the deviation amount t is smaller than 0 (N in S24), the control circuit 44 sets the braking force to the first braking force as originally planned, and brakes the permanent magnet 41 with the first braking force (S3).

[0064] In the modified example described above, by adopting a configuration in which the braking force is switched based on the detection timing of the detection signal DE during the transition period, it is possible to further improve the rate accuracy.

[0065] In the process of S6 described in Fig. 7, an example has been described in which it is determined that there is an advance when the deviation amount t is 0 or more, but it may also be determined that there is a delay when the deviation amount t is 0. Similarly, in the process of S12, an example has been described in which it is determined that there is a delay when the deviation amount t is 0 or less, but it may also be determined that there is an advance when the deviation amount t is 0. Similarly, in the processes of S22 and S24 described in Fig. 8, it may be set appropriately whether to determine that there is an advance or a delay when the deviation amount t is 0.

[0066] Furthermore, the threshold for determining whether the time is ahead or behind is not limited to 0. For example, in the process of S6 described in Fig. 7, it may be determined that the time is ahead if the amount of deviation t is +0.3 seconds or more, and in the process of S12 described in Fig. 7, it may be determined that the time is behind if the amount of deviation t is -0.2 seconds or less.

[0067] In this embodiment and the modified example, the third braking force during the transition period when switching from the first braking force to the second braking force and the third braking force during the transition period when switching from the second braking force to the first braking force are set to the same magnitude, but they may also be different from each other.

[0068] Furthermore, in the present embodiment and the modified example, the third braking force is constant during the transition period. However, the control circuit 44 may vary the magnitude of the third braking force during the transition period. For example, during the transition period when switching from the first braking force to the second braking force, the third braking force may be increased in stages, and during the transition period when switching from the second braking force to the first braking force, the third braking force may be decreased in stages. Specifically, during the transition period when switching from the first braking force to the second braking force, the third braking force may be first set to a duty ratio of 8 / 16 and then switched to 10 / 16. Furthermore, during the transition period when switching from the second braking force to the first braking force, the third braking force may be first set to a duty ratio of 10 / 16 and then switched to 8 / 16. Note that the values ​​of the duty ratios are merely examples and are not limited thereto. Preferably, the duty ratio of the third braking force is at least higher than the duty ratio of the first braking force and lower than the duty ratio of the second braking force.

[0069] The control circuit 44 may also set the magnitude of the third braking force based on the amount of deviation of the detection signal DE detected immediately before the transition period. For example, if the amount of advance in the detection timing of the detection signal DE relative to the output timing of the reference signal OS is large, the control circuit 44 may increase the duty ratio of the third braking force, and if the amount of advance is small, the control circuit 44 may decrease the duty ratio of the third braking force.

[0070] Furthermore, as described in the present embodiment and the modified example, the transition period during which the permanent magnet 41 is braked by the third braking force is different from the periods during which the permanent magnet 41 is braked by the first braking force and the second braking force, and corresponds to one unit cycle, and is preferably a period that ends when the detection signal DE is detected, regardless of the detection timing of the detection signal DE. However, the present invention is not limited to this, and the transition period may continue over multiple unit cycles. [Explanation of symbols]

[0071] 1 mechanical timepiece, 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, 45 detection circuit, 47 frequency divider circuit, 48 oscillation circuit, 50 rectifier circuit, 60 power supply circuit, 70 quartz crystal oscillator, 80 braking circuit.

Claims

1. a speed-regulating mechanism including a rotating body that rotates in both directions; a permanent magnet that rotates in a forward and reverse direction in accordance with the forward and reverse rotation of the rotor; 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 rate adjusting means for adjusting the rate by switching the braking force for braking the permanent magnet between a first braking force and a second braking force greater than the first braking force based on the detection timing of the detection signal; Including, the rate adjusting means brakes the permanent magnet with a third braking force that is greater than the first braking force and less than the second braking force during a transition period when the braking force is switched between the first braking force and the second braking force. Mechanical watch.

2. The rate adjusting means is switching from the third braking force to the second braking force after the detection timing of the detection signal detected during the transition period when switching from the first braking force to the second braking force, regardless of the detection timing of the detection signal; switching from the third braking force to the first braking force after the detection timing of the detection signal detected during the transition period when switching from the second braking force to the first braking force, regardless of the detection timing of the detection signal.

2. The mechanical timepiece according to claim 1.

3. The rate adjusting means is when a detection timing of the detection signal detected during the transition period when switching from the first braking force to the second braking force is delayed with respect to the reference timing, switching from the third braking force to the first braking force after the detection timing; when a detection timing of the detection signal detected during the transition period when switching from the second braking force to the first braking force is advanced with respect to the reference timing, switching from the third braking force to the second braking force after the detection timing.

2. The mechanical timepiece according to claim 1.

4. The rate adjusting means is If the detection timing of the detection signal detected when braking the permanent magnet with the first braking force is delayed with respect to the reference timing, continuing braking the permanent magnet with the first braking force, when a detection timing of the detection signal detected when braking the permanent magnet with the first braking force is advanced with respect to the reference timing, switching from the first braking force to the third braking force after the detection timing.

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

5. The rate adjusting means is If the detection timing of the detection signal detected when braking the permanent magnet with the second braking force is ahead of the reference timing, continuing braking the permanent magnet with the second braking force, When a detection timing of the detection signal detected when braking the permanent magnet with the second braking force is delayed with respect to the reference timing, the braking force is switched from the second braking force to the third braking force after the detection timing.

5. The mechanical timepiece according to claim 4.

6. the rate adjusting means changes the magnitude of the third braking force during the transition period.

2. The mechanical timepiece according to claim 1.

7. The rate adjusting means is increasing the third braking force in a stepwise manner during the transition period when switching from the first braking force to the second braking force; The third braking force is gradually reduced during the transition period when the braking force is switched from the second braking force to the first braking force.

7. The mechanical timepiece according to claim 6.

8. The rate adjusting means is setting the magnitude of the third braking force based on the detection timing of the detection signal detected immediately before the transition period; 2. The mechanical timepiece according to claim 1.

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