Mechanical watch

Abstract

This prevents excessive braking force from being applied and maintains accuracy in the timekeeping system. [Solution] The mechanical clock 1 includes a speed control mechanism 30 which includes a power mainspring 11, a balance wheel 31 driven by the power from the power mainspring 11, and a hairspring 32 which elastically deforms to cause the balance wheel 31 to rotate in forward and reverse directions; a permanent magnet 41, a coil 43, a detection circuit 45 which detects a detection signal DE based on a detection voltage generated in the coil 43 by the forward and reverse rotational motion of the permanent magnet 41, a braking circuit 80 which generates a braking force to brake the permanent magnet 41 by short-circuiting the terminals of the coil 43, and a control circuit 44 which increases the braking force when it is determined that the detection timing DE is ahead based on the amount of deviation of the detection timing DE relative to a predetermined reference timing, and the control circuit 44 suppresses the amount of increase in braking force based on the history of the deviation amount.

Description

Technical Field

[0001] The present invention relates to a mechanical watch.

Background Art

[0002] In Patent Document 1 below, a mechanical watch is disclosed that generates electricity by providing a permanent magnet that rotates integrally with a cam wheel, and performs pace adjustment based on the back electromotive voltage generated in response to the rotation of the permanent magnet. In the mechanical watch of Patent Document 1 below, pace adjustment is performed by applying a braking force to the permanent magnet.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a mechanical watch as described above, when an excessive braking force is applied, it may become impossible to perform appropriate pace adjustment.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a mechanical watch that suppresses the application of an excessive braking force and maintains pace accuracy.

Means for Solving the Problems

[0006] (1) A mechanical clock comprising: a power source; a balance wheel driven by power from the power source; a hairspring elastically deformed to cause the balance wheel to rotate in forward and reverse directions; a bipolar permanent magnet that rotates in forward and reverse directions in conjunction with the forward and reverse rotation of the balance wheel; a coil; a detection circuit that detects a detection signal based on a detection voltage generated in the coil by the forward and reverse rotation of the permanent magnet; a braking circuit that generates a braking force to brake the permanent magnet by short-circuiting the terminals of the coil; and a control circuit that increases the braking force when it is determined that the detection timing is ahead based on the amount of deviation of the detection timing of the detection signal with respect to a predetermined reference timing, wherein the control circuit suppresses the amount of increase in the braking force based on the history of the amount of deviation.

[0007] (2)(1) A mechanical clock in which the control circuit suppresses the amount of increase in the braking force when it determines that the amount of deviation is decreasing based on the history.

[0008] (3) A mechanical clock in which, in (1) or (2), the control circuit maintains the braking force when it determines that the amount of deviation is decreasing based on the history.

[0009] (4) In any of (1) to (3), the control circuit suppresses the amount of increase in the braking force when the advance amount of the current detection timing relative to the reference timing is smaller than the advance amount of the previous detection timing relative to the reference timing.

[0010] (5) In any of (1) to (4), the control circuit reduces the braking force if it determines that the detection timing is delayed with respect to the reference timing.

[0011] (6) A mechanical clock in which, in any of (1) to (5), the control circuit is driven by the supply of a back electromotive force generated in the coil by the forward and reverse rotational motion of the permanent magnet. [Effects of the Invention]

[0012] According to aspects (1) to (6) of the present invention described above, it is possible to provide a mechanical watch that suppresses the application of excessive braking force and maintains accuracy in timekeeping. [Brief explanation of the drawing]

[0013] [Figure 1] This is an exploded perspective view showing the base plate and the various components incorporated into it. [Figure 2] This is a perspective view showing the escapement mechanism, governor, and surrounding components. [Figure 3] This is a block diagram showing the overall structure of a mechanical watch. [Figure 4] This diagram illustrates the back electromotive force detected by a coil as a permanent magnet rotates. [Figure 5] This graph shows the changes in braking rank and deviation amount in this embodiment. [Figure 6] This is a flowchart showing the braking control in this embodiment. [Figure 7] This is a flowchart showing the braking control in a first modified example of this embodiment. [Figure 8] This is a flowchart showing the braking control in a second modified example of this embodiment. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments of the present invention (hereinafter referred to as "this embodiment") will be described in detail with reference to the drawings.

[0015] The overall configuration of the mechanical clock 1 will be described with reference to Figures 1 to 4. As shown in Figure 2, the mechanical clock 1 comprises a mainspring 11, an escapement mechanism 20, a regulating mechanism 30, and a hand 131. Power from the mainspring 11 is transmitted to the escapement mechanism 20 and the regulating mechanism 30 through the gear train 12. Each of these components and mechanisms is incorporated into the base plate 10.

[0016] The escapement mechanism 20 continuously applies a force for reciprocating movement to the ratchet wheel 31 provided in the speed control mechanism 30, and rotates each gear in the gear train 12 at a constant speed by the regular vibration from the ratchet wheel 31. As shown in FIG. 2, the escapement mechanism 20 includes a gang gear 21 and an anchor 22. In the present embodiment, the ratchet wheel 31 is designed to make one reciprocating motion in 2 seconds, and the gang gear 21 is configured to operate one step per second.

[0017] As shown in FIGS. 1 and 2, the speed control mechanism 30 includes a ratchet wheel 31 which is a rotating body, and a hairspring 32. The ratchet wheel 31 is supported so as to be rotatable forward and backward about a ten-pin 311 which is a rotating shaft as a rotation center. It is preferable that a pendulum seat for fixing a pendulum weight is provided on the ten-pin 311.

[0018] The hairspring 32 has a spiral shape, and its outer end is fixed to a hairspring holder 34 (see FIG. 1), and its inner end is preferably fixed to the ten-pin 311. The speed control mechanism 30 repeatedly rotates the ratchet wheel 31 forward and backward (reciprocating motion) in a certain cycle by the expansion and contraction motion (elastic deformation) of the hairspring 32.

[0019] In the present embodiment, the hairspring 32 is made of a resin material with a low Young's modulus. Thereby, the low-speed vibration of the ratchet wheel 31 can be realized as compared with the case where the hairspring 32 is made of a metal material. Further, in the present embodiment, the rotation angle [deg] of the ratchet wheel 31 in the state at the neutral position (natural length position) of the elastic deformation of the hairspring 32 is set to 0°. Power from the mainspring 11 is supplied to the ratchet wheel 31 in a state near the neutral position of the elastic deformation of the hairspring 32. That is, the 0° position is the power supply position.

[0020] Furthermore, the mechanical watch 1 includes a beat adjustment means 40. The beat adjustment means 40 includes a permanent magnet 41, a stator 42, and a coil 43 shown in FIG. 2 and the like, a control circuit 44, a detection circuit 45, a frequency division circuit 47, an oscillation circuit 48, and a braking circuit 80 shown in FIG. 3.

[0021] The permanent magnet 41 is a bipolar magnetized disc-shaped rotating body, and as shown in Figure 4, it is a magnet having an N pole portion 411 and an S pole portion 412, which are magnetized radially as an N pole and an S pole. In addition, an insertion hole is formed in the center of the permanent magnet 41 through which the balance staff 311 is inserted. The permanent magnet 41 rotates in forward and reverse directions together with the balance staff 31 (balance staff 311) so that its rotation angle is the same as the rotation angle of the balance staff 31.

[0022] The stator 42 is made of a soft magnetic material and comprises a first magnetic part 421 having a first end 421a and a second magnetic part 422 having a second end 422a, and together with the coil 43, constitutes a magnetic circuit. The stator 42 is installed so as to generate a magnetic torque on the permanent magnet 41 in accordance with the rotation angle of the permanent magnet 41.

[0023] The control circuit 44 controls the operation of each circuit in the rate adjustment means 40. The control circuit 44 sets a braking force to brake the permanent magnet 41 by controlling the braking circuit 80. The braking force is applied to the permanent magnet 41 based on, for example, an electromagnetic brake. The electromagnetic brake is preferably based on an induced electromotive force that short-circuits the first and second terminals of the coil 43 to create a closed loop, generating a magnetic field in a direction that opposes the change in magnetic flux generated in the coil 43 as the permanent magnet 41 rotates.

[0024] The braking circuit 80 is configured to apply to the permanent magnet 41 the braking force corresponding to the currently set braking rank from among multiple braking forces corresponding to each of the multiple braking ranks.

[0025] The detection circuit 45 detects a 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. The detection signal DE is preferably detected by the detection circuit 45 when a back electromotive force voltage of a predetermined threshold Vth or higher is generated. In this embodiment, the detection signal DE is a pulse signal synchronized with the start timing of the unit period in the back electromotive force voltage. Here, the start timing of the unit period is the timing when the balance wheel 31 passes the 0° position, and corresponds to the zero-crossing point where the back electromotive force voltage switches from negative to positive. The determination of the detection signal which is the start timing of the unit period may be performed, for example, by setting a non-determination period in which zero-crossing points other than the start timing of the unit period, where the back electromotive force voltage switches from negative to positive, are not determined to be detection signals.

[0026] The predetermined threshold Vth is a value near 0[V], for example, +10[mV]. Note that noise may instantaneously occur near the threshold Vth of 0[V] due to external factors such as shock. To avoid false detections caused by such noise, for example, the timing of the determination of the detection signal DE for rotation detection may be set to one of the timings when the detection signal DE is detected two or more predetermined times consecutively (for example, the timing of the last detection). 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 below the predetermined threshold -Vth occurs.

[0027] The oscillation 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 oscillation 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 (predetermined reference timing) of the reference signal OS is preset to correspond to the detection signal DE detected when there is neither a lead nor a lag in the forward and reverse rotational motion of the balance wheel 31. In this embodiment, the reference signal OS is output approximately every 500 [ms]. The predetermined reference timing may be a timing that is a predetermined time ahead or behind the output timing of the reference signal OS.

[0028] Mechanical clock 1 has a power generation function using the principle of electromagnetic induction. In this embodiment, the speed control mechanism 30 functions as part of the generator. Specifically, the permanent magnet 41 rotates in the forward and reverse directions in conjunction with the forward and reverse rotational motion of the balance wheel 31, and power is generated by the back electromotive force produced in the coil 43 based on the change in the magnetic field caused by the motion of the permanent magnet 41. The power extracted by this operating principle is used to start the power supply circuit 60. Once the power supply circuit 60 is started, the control circuit 44 becomes drivable.

[0029] The rectifier circuit 50 rectifies the current generated in the coil 43 by the motion of the permanent magnet 41 accompanying the forward and reverse rotational motion of the balance wheel 31 of the speed control mechanism 30. The power supply circuit 60, for example, includes a capacitor and stores power to drive the control circuit 44 based on the current rectified by the rectifier circuit 50.

[0030] Note that the rate adjustment means 40 shown in Figure 3 is just one example, and the configuration is not limited to the one shown, as long as it can realize the functions described above.

[0031] Referring to Figure 4, the relationship between the rotation angle of the permanent magnet 41 and the back electromotive force will be explained. Here, an example is described in which the swing angle (maximum angle) of the balance wheel 31 is pre-set to ±340°. It is preferable that the swing angle of the balance wheel 31 be at least ±180°.

[0032] The back electromotive force generated in the coil 43 due to the change in the magnetic field when the north pole portion 411 of the permanent magnet 41 moves toward the first end portion 421a of the stator 42 is defined as a "positive" back electromotive force. The back electromotive force generated in the coil 43 due to the change in the magnetic field when the north pole portion 411 moves toward the first end portion 421a of the stator 42 is defined as a "negative" back electromotive force.

[0033] At the 0° position, the permanent magnet 41 is in a position of magnetic equilibrium, and the back electromotive force generated in the coil 43 is zero. At the 0° position, the permanent magnet 41 is powered by the power spring 11. Also, as the permanent magnet 41 rotates from the 0° position to the 180° position, the N pole portion 411 moves in a direction toward the first end portion 421a. Therefore, as the permanent magnet 41 rotates from the 0° position to the 180° position, a positive back electromotive force is generated in the coil 43.

[0034] Since the permanent magnet 41 is in a magnetically balanced position at the 0° position, it is also in a magnetically balanced position at the 180° position, and the back electromotive force generated in the coil 43 is 0. When the permanent magnet 41 rotates from the 180° position to the 340° position, the N pole portion 411 moves away from the first end portion 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.

[0035] The angular velocity of the permanent magnet 41 becomes 0 at the 340° position, which is the turning point of the reciprocating motion. Therefore, the back electromotive force generated in the coil 43 is 0 at the 340° position. Once the permanent magnet 41 reaches the 340° position, it begins to rotate toward the 180° position due to the elastic force of the hairspring 32. As the permanent magnet 41 rotates from the 340° position toward the 180° position, the N pole portion 411 moves toward the first end portion 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.

[0036] As the permanent magnet 41 rotates from the 180° position towards the 0° position, the N pole portion 411 moves away from the first end portion 421a. As a result, a negative back electromotive force is generated in the coil 43 when the permanent magnet 41 rotates from the 180° position towards the 0° position.

[0037] When the permanent magnet 41 reaches the 0° position, power is supplied from the power spring 11. As the permanent magnet 41 rotates from the 0° position towards the -180° position, the N pole portion 411 moves toward the first end portion 421a. Therefore, a positive back electromotive force is generated in the coil 43 when the permanent magnet 41 rotates from the 0° position towards the -180° position.

[0038] Just as the permanent magnet 41 is in a magnetically balanced position at 180°, it is also in a magnetically balanced position at -180°, and the back electromotive force generated in the coil 43 is 0 at the -180° position of the permanent magnet 41. When the permanent magnet 41 rotates from the -180° position to the -340° position, the N pole portion 411 moves away from the first end portion 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.

[0039] The angular velocity of the permanent magnet 41 becomes 0 at the -340° position, which is the turning point of the reciprocating motion. Therefore, the back electromotive force generated in the coil 43 is 0 at the -340° position. Once the permanent magnet 41 reaches the -340° position, it begins to rotate toward the -180° position due to the elastic force of the hairspring 32. As the permanent magnet 41 rotates from the -340° position toward the -180° position, the N pole portion 411 moves toward the first end portion 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.

[0040] As the permanent magnet 41 rotates from the -180° position towards the 0° position, the N pole portion 411 moves away from the first end portion 421a. Therefore, a negative back electromotive force is generated in the coil 43 as the permanent magnet 41 rotates from the -180° position towards the 0° position.

[0041] If the above operations are repeated and there is no advance or lag in the forward or reverse rotational motion of the balance wheel 31 (permanent magnet 41), the back electromotive force shown in Figure 4 is generated in the coil 43.

[0042] Next, an example of braking control by the control circuit 44 in this embodiment will be described.

[0043] In this embodiment, the control circuit 44 sets the braking force based on the amount of deviation between the output timing of the reference signal OS and the detection timing of the detection signal DE. If the deviation amount t, calculated by subtracting the detection timing of the detection signal DE from the output timing of the reference signal OS, is 0 or greater, the control circuit 44 increases the braking force of the electromagnetic brake DB to slow down the rate because it is "leading". If the deviation amount t is less than 0, the control circuit 44 decreases the braking force of the electromagnetic brake DB to advance the rate because it is "lagging". The electromagnetic brake DB is output in a series of single pulses, and it is preferable that the strength of the braking force be switched by adjusting the length of the single pulses and the output interval (duty cycle) of the single pulses.

[0044] If excessive braking force is applied, the amplitude of the balance wheel 31 decreases, which can prevent proper rate adjustment. For example, if the amplitude of the balance wheel 31 falls below 180 degrees, the waveform of the back electromotive force explained with reference to Figure 4 cannot be obtained, making it impossible to properly adjust the rate based on the back electromotive force. In particular, since the mechanical watch 1 is driven by the power mainspring 11, as the power from the power mainspring 11 weakens with the passage of time, excessive braking force tends to be applied.

[0045] Therefore, in this embodiment, in order to suppress the application of excessive braking force, even when the detection signal DE is leading the reference signal OS, if the amount of lead has decreased compared to the previous detection signal DE, a configuration is adopted in which the braking force is maintained rather than increased.

[0046] In the graph in Figure 5, the horizontal axis represents the number of measurements (number of detections of the detection signal DE). The vertical axis in the upper graph of Figure 5 represents the braking rank, and the vertical axis in the lower graph of Figure 5 represents the amount of deviation [ms]. The example shown in Figure 5 describes an example in which the braking circuit 80 is configured to apply electromagnetic brakes DB with braking ranks 0 to 8. Note that the braking force of electromagnetic brake DB with braking rank 8 is the greatest, and the braking force decreases as the rank decreases.

[0047] In the example shown in Figure 5, the deviation of the first detection signal DE is approximately +70 [ms], indicating that the detection signal DE is leading the reference signal OS. Therefore, in order to reduce the deviation by suppressing the amount of lead, the damping rank until the next detection signal DE is detected is increased from "4" to "5".

[0048] The deviation of the second detection signal DE is approximately +80 [ms], indicating that the detection signal DE is leading the reference signal OS. Furthermore, the deviation is larger than that of the first detection signal DE. In other words, the braking force is insufficient. Therefore, in order to reduce the deviation by suppressing the amount of lead, the braking rank until the next detection signal DE is detected is increased from "5" to "6".

[0049] The deviation of the third detection signal DE is approximately +60 ms, indicating that the detection signal DE is leading the reference signal OS. Furthermore, the deviation is smaller compared to the second detection signal DE. In other words, although it is still leading, a braking force is still in effect. Therefore, to prevent the braking force from becoming excessively large, the braking rank is maintained until the next detection signal DE is detected.

[0050] The deviation of the fourth detection signal DE is approximately +40 ms, indicating that the detection signal DE is leading the reference signal OS. Furthermore, the deviation is smaller compared to the third detection signal DE. In other words, although it is still leading, a braking force is still in effect. Therefore, to prevent the braking force from becoming excessively large, the braking rank is maintained until the next detection signal DE is detected.

[0051] The deviation of the fifth detection signal DE is approximately +20 ms, indicating that the detection signal DE is leading the reference signal OS. Furthermore, the deviation is smaller compared to the fourth detection signal DE. In other words, although it is still leading, a braking force is still in effect. Therefore, to prevent the braking force from becoming excessively large, the braking rank is maintained until the next detection signal DE is detected.

[0052] The deviation of the sixth detection signal DE is approximately -10 ms, indicating that the detection signal DE is lagging behind the reference signal OS. Therefore, in order to advance the detection signal DE, the damping rank until the next detection signal DE is detected is lowered from "6" to "5".

[0053] The deviation of the 7th detection signal DE is approximately +10 [ms], indicating that the detection signal DE is leading the reference signal OS. Therefore, to delay the detection signal DE, the damping rank until the next detection signal DE is detected is increased from "5" to "6".

[0054] The deviation of the 8th detection signal DE is approximately -10 ms, indicating that the detection signal DE is lagging behind the reference signal OS. Therefore, in order to advance the detection signal DE, the damping rank until the next detection signal DE is detected is lowered from "6" to "5".

[0055] As explained above, in this embodiment, if the detection signal DE is leading, the braking rank is increased as a general rule. However, if the detection signal DE is leading and the amount of deviation (leading) is smaller than the previous time, the braking rank is maintained. By performing this control, it is possible to suppress the braking force from becoming excessively large. In the example shown in Figure 5, by suppressing the braking force from becoming excessively large, the amount of deviation from becoming large on the negative side is suppressed. As a result, it is possible to maintain the appearance of the back electromotive force as shown in Figure 4, and to perform appropriate rate adjustment.

[0056] Furthermore, by suppressing excessive braking force, energy loss due to high-level braking force is prevented and optimized, allowing a sufficient and continuous current to be generated in the coil 43 based on the change in the magnetic field caused by the movement of the permanent magnet 41. As a result, a decrease in power generation can be suppressed.

[0057] Next, with reference to Figure 6, the processing flow of braking control in this embodiment will be described. First, the power supply circuit 60 is activated by the power generation caused by the movement of the permanent magnet 41, and the control circuit 44 controls the braking circuit 80 to brake the permanent magnet 41 based on the current braking rank (S1). The current braking rank immediately after the start of braking control is arbitrary.

[0058] When the detection signal DE is detected (Y in S2), the control circuit 44 calculates the deviation amount t of the detection signal DE (S3). If the deviation amount t is 0 or less (N in S4), the control circuit 44 lowers the braking rank by one level (S5).

[0059] The control circuit 44 increases the braking rank by one level (S7) if the amount of deviation t is greater than 0 (Y in S4) and the amount of deviation t in the current direction of travel is greater than or equal to the amount of deviation t' in the previous direction of travel (N in S6).

[0060] The control circuit 44 maintains the braking rank (S8) if the amount of deviation t is greater than 0 (Y in S4) and the amount of deviation t in the current direction of travel is less than the amount of deviation t' in the previous direction of travel (Y in S6).

[0061] After setting the current braking rank through processes S5, S7, and S8, the process returns to S1 and repeats.

[0062] Next, with reference to Figure 7, the processing flow of braking control in the first modified example will be described. Note that the same reference numerals are used for processes similar to those described in Figure 6, and their detailed explanations are omitted.

[0063] In the first modified example, if the current deviation amount t in the direction of travel is less than the previous deviation amount t' for two consecutive times (Y in S16), the braking rank is maintained (S8). That is, even if the current deviation amount t in the direction of travel is less than the previous deviation amount t' for travel, if this state is not consecutive (N in S16), the braking rank is increased by one level (S7).

[0064] In addition, in S16, the determination of whether or not to maintain the braking rank may be made based on whether the current deviation amount t in the direction of travel is less than the previous deviation amount t' has occurred for three or more consecutive times.

[0065] In the control of the first modified example, it is possible to avoid maintaining braking force even when it is necessary to increase it. For example, if the reason for the reduced deviation in the direction of travel is a false detection due to an external factor such as an impact, it is possible to avoid maintaining braking force. This allows for more appropriate rate adjustment.

[0066] Next, with reference to Figure 8, the processing flow of braking control in the second modified example will be described. Note that the same reference numerals are used for processes similar to those described in Figure 6, and their detailed explanations are omitted.

[0067] In the second modified example, the control circuit 44 lowers the braking rank by two levels (S15) if the displacement amount t is 0 or less (N in S4). Also, the control circuit 44 raises the braking rank by two levels (S17) if the displacement amount t is greater than 0 (Y in S4) and the displacement amount t in the current direction of travel is greater than or equal to the displacement amount t' in the previous direction of travel (N in S6).

[0068] Then, the control circuit 44 raises the braking rank by one level (S18) if the amount of deviation t is greater than 0 (Y in S4) and the amount of deviation t in the current direction of travel is less than the amount of deviation t' in the previous direction of travel (Y in S6). Thus, in this second modified example, instead of maintaining the braking rank in S18, the amount of increase is made smaller than in S17.

[0069] The amount of change in the braking rank in the second modified example is just one example and is not limited to it. For example, the amount of change in the braking rank in S15 and S17 may be 3 or more, and the amount of increase in the braking rank in S18 may be 2 or more. Also, the absolute value of the amount of decrease in the braking rank in S15 and the absolute value of the amount of increase in the braking rank in S17 may be different.

[0070] In the control of the second modified example, if the detection signal DE is advanced, the braking rank is increased by two levels as a general rule. However, if the detection signal DE is advanced and the amount of deviation (advance) is smaller than the previous time, the braking rank is increased by one level. By performing this type of control, it is possible to suppress the braking force from becoming excessively large. Furthermore, in the second modified example, by significantly changing the braking rank compared to this embodiment, it is expected that the detection timing of the detection signal DE can be matched to the output timing of the reference signal OS more quickly.

[0071] The embodiment, the first modified example, and the second modified example described above are examples of braking control and are not limited to these examples. The control circuit 44 may suppress the amount of increase in braking force based on the history of the deviation amount. In other words, it may set the current braking rank not only based on the deviation amount of the current detection signal DE, but also based on the deviation amount of the detection signal DE from previous times.

[0072] Furthermore, the control circuit 44 may determine whether the amount of deviation of the detection signal DE is decreasing based on the history of deviation amounts, and if it determines that there is a decreasing trend, it may suppress the amount of increase in braking force. A decreasing trend may mean, for example, that the advance amount of the detection signal DE has decreased for at least two consecutive times. Alternatively, a decreasing trend may mean that the decrease in the advance amount of the detection signal DE has occurred at a predetermined rate (for example, a decrease in 7 or more out of 10 detections).

[0073] Furthermore, in addition to the control that suppresses the increase in braking force as explained with reference to Figures 6 to 8, the control circuit 44 may also, when the detection signal DE is delayed, determine whether the absolute value of the deviation is decreasing based on the history of the deviation amount of the detection signal DE, and if it is determined that it is decreasing, perform control that suppresses the decrease in braking force.

[0074] Furthermore, the control circuit 44 may perform the rank switching control, as explained with reference to Figures 6 to 8, not every unit period, but every two unit periods. For example, in S2 in Figures 6 to 8, the process may proceed to S3 after detecting the detection signal DE twice. This ensures stable control even if a difference in the amplitude of the balance wheel 31 occurs due to assembly errors in the mechanical clock 1.

[0075] Furthermore, the rank switching control described with reference to Figures 6 to 8 may be performed according to the voltage supplied from the power supply circuit 60 to the control circuit 44. For example, it is preferable that this switching control not be performed immediately after the power supply circuit 60 has started up and the voltage supplied from the power supply circuit 60 to the control circuit 44 is below a predetermined value. That is, it is preferable that this rank switching control be started when the voltage supplied from the power supply circuit 60 to the control circuit 44 becomes above a predetermined value. This makes it possible to obtain a high voltage by performing chopper amplification at a high rank immediately after the power supply circuit 60 has started up. In addition, energy loss can be suppressed by preventing excessive braking force from being applied when the voltage exceeds a certain value after the power supply circuit 60 has started up. [Explanation of symbols]

[0076] 1 Mechanical clock, 10 Main plate, 11 Power mainspring, 12 Gear train, 131 Hands, 20 Escapement mechanism, 21 Escape wheel, 22 Lever, 30 Regulating mechanism, 31 Balance wheel, 311 Balance stem, 32 Hairspring, 34 Hairspring holder, 40 Rate adjustment mechanism, 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 Oscillator circuit, 50 Rectifier circuit, 60 Power supply circuit, 70 Quartz oscillator, 80 Damping circuit.

Claims

1. Power source and A regulating mechanism including a balance wheel driven by power from the aforementioned power source, and a hairspring that elastically deforms to cause the balance wheel to rotate in forward and reverse directions, A bipolarized permanent magnet that rotates in the forward and reverse directions in conjunction with the forward and reverse rotational motion of the aforementioned balance wheel, Coil and, A detection circuit that detects a detection signal based on a detection voltage generated in the coil by the forward and reverse rotational motion of the permanent magnet, A braking circuit that generates a braking force to brake the permanent magnet by short-circuiting the terminals of the coil, If it is determined that the detection timing is ahead based on the amount of deviation of the detection timing of the detection signal from a predetermined reference timing, the control circuit increases the braking force, It has, The control circuit suppresses the amount of increase in the braking force based on the history of the deviation amount. Mechanical watch.

2. If the control circuit determines, based on the history, that the amount of deviation is decreasing, it will suppress the amount of increase in the braking force. The mechanical clock according to claim 1.

3. If the control circuit determines that the amount of deviation is decreasing based on the history, it maintains the braking force. The mechanical clock according to claim 1.

4. The control circuit suppresses the increase in braking force if the advance amount of the current detection timing relative to the reference timing is smaller than the advance amount of the previous detection timing relative to the reference timing. The mechanical clock according to claim 1.

5. If the control circuit determines that the detection timing is delayed relative to the reference timing, it reduces the braking force. The mechanical clock according to claim 1.

6. The control circuit is driven by the supply of back electromotive force generated in the coil by the forward and reverse rotational motion of the permanent magnet. A mechanical clock according to any one of claims 1 to 5.

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