Mechanical watch

Abstract

To provide a mechanical watch capable of stably adjusting the rate.SOLUTION: A mechanical watch 1 includes: a balance wheel 31 that performs forward and reverse rotation; a permanent magnet 41 that performs forward and reverse rotation along with forward and reverse rotation of the balance wheel 31; a coil 43 that generates a counter-electromotive voltage according to the forward and reverse rotation of the permanent magnet 41; a detection circuit 45 that detects a first detection signal DE1 according to the timing when the back electromotive voltage switches from negative to positive; and rate adjustment means 40 that adjusts the rate based on the detection timing of a reference detection signal BP, which is the reference of the unit period of the balance wheel 31 forward and reverse rotation in the first detection signal DE1. The rate adjustment means 40 is configured so as to, when the first detection signal DE1 is detected within a certain time from the detection timing of the previous reference detection signal BP, the next detected first detection signal DE1 is set as the reference detection signal BP.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] Patent Document 1 below discloses a mechanical watch that generates electricity by providing a permanent magnet that rotates integrally with a ratchet wheel, and performs pace adjustment based on a back electromotive voltage generated in response to the rotation of 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 the above mechanical watch, pace adjustment is performed by comparing the timing of a detection signal detected in response to a back electromotive voltage with a predetermined reference signal. In such a configuration, if pace adjustment is performed based on a detection signal different from the detection signal that should originally be compared with the reference signal, it becomes impossible to perform the desired pace adjustment. As a result, there is a risk that the pace accuracy will deteriorate.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a mechanical watch capable of stably performing pace adjustment.

Means for Solving the Problems

[0006] (1) A mechanical clock having a ten-ring that rotates forward and backward, a permanent magnet that rotates forward and backward along with the forward and backward rotation of the ten-ring, a coil in which a back electromotive voltage is generated in response to the forward and backward rotation of the permanent magnet, a detection circuit that detects a detection signal according to either one of the timings when the back electromotive voltage switches from positive to negative and from negative to positive, and a step adjustment means that performs step adjustment based on the detection timing of a reference detection signal that is a reference for a unit cycle in the forward and backward rotation of the ten-ring among the detection signals. When the detection signal is detected before a predetermined time has elapsed from the detection timing of the previous reference detection signal, the step adjustment means sets the next detected detection signal as the reference detection signal.

[0007] (2) In (1), when the detection signal is not detected before the predetermined time has elapsed from the detection timing of the previous reference detection signal, the step adjustment means sets the detection signal detected after the predetermined time has elapsed as the reference detection signal. A mechanical clock.

[0008] (3) In (1) or (2), the step adjustment means starts a non-determination period in which it does not determine that the detection signal is the reference detection signal based on the detection timing of the reference detection signal. A mechanical clock.

[0009] (4) In (3), when the detection signal is detected during the non-determination period, the non-determination period is ended before the predetermined time has elapsed. A mechanical clock.

[0010] (5) In (3) or (4), the detection circuit detects a first detection signal that is the detection signal according to either one of the timings when the back electromotive voltage switches from positive to negative and from negative to positive, and detects a second detection signal according to either the other timing when the back electromotive voltage switches from positive to negative and from negative to positive. When the second detection signal is detected twice during the non-determination period, the step adjustment means ends the non-determination period before the predetermined time has elapsed. A mechanical clock.

[0011] (6) In any one of (3) to (5), when the detection timing of the detection signal detected during the non-determination period is later than a predetermined threshold value, the mechanical clock waits for the elapse of the predetermined time and then ends the non-determination period.

[0012] (7) In any one of (3) to (6), the detection circuit detects a first detection signal, which is the detection signal, in response to either one of the timings when the back electromotive voltage switches from positive to negative and from negative to positive, and detects a second detection signal in response to the other timing when the back electromotive voltage switches from positive to negative and from negative to positive. When the detection timing of the second detection signal detected during the non-determination period is later than a predetermined threshold value, the mechanical clock waits for the elapse of the predetermined time and then ends the non-determination period.

[0013] (8) In any one of (3) to (7), when the non-determination period ends by elapsing the predetermined time, the mechanical clock performs control to increase the pace.

Advantages of the Invention

[0014] According to the aspects (1) to (8) of the present invention described above, it is possible to provide a mechanical clock capable of stably performing pace adjustment.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention (hereinafter, these embodiments) will be described in detail with reference to the drawings.

[0017] The mechanical clock 1 includes a mainspring 11, and controls the movement of the mainspring 11 by an escapement mechanism 20 and a speed regulating mechanism 30 to drive the hands 131. The power from the mainspring 11 is transmitted to the escapement mechanism 20 and the speed regulating mechanism 30 through the wheel train 12. These members and mechanisms are incorporated in the floor board 10.

[0018] As shown in FIG. 2, the escapement mechanism 20 includes a crown wheel 21 and an anchor 22. The escapement mechanism 20 continuously applies a force for reciprocating movement to the ten wheel 31 provided in the speed regulating mechanism 30, and rotates each gear in the wheel train 12 at a constant speed by regular vibrations from the ten wheel 31. In the present embodiment, the ten wheel 31 is preset to perform one reciprocating operation in 2 seconds, and the crown wheel 21 is configured to perform one step operation per second.

[0019] As shown in FIGS. 1 and 2, the speed regulating mechanism 30 includes a ten wheel 31 and a hairspring 32. The ten wheel 31 is rotatably supported by the power transmitted by the wheel train 12 with the ten shaft 311, which is a rotating shaft, as the center of rotation. The hairspring 32 is spiral, the outer end thereof is fixed to the hairspring holder 34 (see FIG. 1), and the inner end thereof is fixed to the ten shaft 311. The speed regulating mechanism 30 repeatedly rotates the ten wheel 31 in the forward and reverse directions (reciprocating motion) at a constant period by the expansion and contraction motion (elastic deformation) of the hairspring 32.

[0020] In this embodiment, the beard spring 32 is made of a resin material with a low Young's modulus. As a result, the low-speed vibration of the balance wheel 31 can be achieved as compared with the case where the beard spring 32 is made of a metal material. Further, in this embodiment, the rotation angle [deg] of the balance wheel 31 in the state at the neutral position of the elastic deformation of the beard spring 32 is set to 0°. Note that the neutral position of the elastic deformation of the beard spring 32 is the position where the beard spring 32 is at its natural length. Also, power from the power spring 11 is supplied to the balance wheel 31 in a state near the neutral position of the elastic deformation of the beard spring 32.

[0021] The mechanical watch 1 includes a rate adjustment means 40. The rate 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 shown in FIG. 3, a detection circuit 45, a frequency division circuit 47, an oscillation circuit 48, and a braking circuit 80.

[0022] The permanent magnet 41 is a disk-shaped rotating body magnetized with two poles, and as shown in FIG. 4, it is a magnet having an N-pole portion 411 and an S-pole portion 412 magnetized with N and S poles in the radial direction. Further, an insertion hole through which the balance staff 311 is inserted is formed in the central portion of the permanent magnet 41. The permanent magnet 41 rotates forward and backward together with the balance wheel 31 so that the rotation angle becomes the same as the rotation angle of the balance wheel 31 in accordance with the forward and backward rotational movement of the balance wheel 31 (balance staff 311).

[0023] The stator 42 is made of a soft magnetic material and includes a first magnetic portion 421 having a first end portion 421a and a second magnetic portion 422 having a second end portion 422a, and constitutes 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.

[0024] The control circuit 44 controls the operations of the respective circuits included in the step adjustment means 40 and switches the step adjustment control. The control circuit 44 can perform braking control for controlling the braking force for braking the permanent magnet 41 by controlling the braking circuit 80. The braking force can act on the permanent magnet 41 based on, for example, an electromagnetic brake. Note that the electromagnetic brake can obtain the braking force by a generated electromotive force that short - circuits the first terminal and the second terminal of the coil 43 to form a closed - loop state and generates a magnetic field in a direction that obstructs the change in magnetic flux generated in the coil 43 as the permanent magnet 41 rotates.

[0025] The detection circuit 45 detects a 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. In the present embodiment, the detection signal DE is a pulse signal synchronized with the timing when the back - electromotive voltage becomes 0, and is detected by the detection circuit 45 when a back - electromotive voltage equal to or higher than a predetermined threshold value Vth occurs. The predetermined threshold value Vth is a value near 0 [V]. For example, the positive threshold value Vth can be + 10 [mV], and the negative threshold value Vth (hereinafter referred to as Vth -) can be - 10 [mV]. Note that noise may be instantaneously generated near 0 [V] which is the threshold value Vth due to external factors such as impact. To avoid false detection caused by such noise, etc., for example, the discrimination timing of the detection signal DE (zero - cross point) for rotation detection can be set as any timing (for example, the last detected timing) when the detection signal DE is continuously detected a predetermined number of times or more.

[0026] The oscillation circuit 48 outputs a predetermined oscillation signal based on the oscillation frequency of the crystal oscillator 70. The frequency - dividing circuit 47 divides the oscillation signal output from the oscillation circuit 48. In the present embodiment, the frequency - dividing circuit 47 generates a reference signal OS that is output at intervals corresponding to the unit cycle of the speed - adjusting mechanism 30 by dividing the oscillation signal based on the crystal oscillator 70. The output timing of the reference signal OS is preset so as to correspond to the detection timing of the reference detection signal BP among the detection signals DE when the forward and reverse rotational movements of the sun gear 31 are performed normally. In the present embodiment, it is output approximately every 500 [ms].

[0027] The step adjustment means 40 performs step adjustment based on the reference detection signal BP and the reference signal OS. For example, when the detection timing of the reference detection signal BP is ahead of the output timing of the reference signal OS, braking is performed to slow down the forward and reverse rotational movements of the permanent magnet 41. Note that the step adjustment means 40 may be any means capable of realizing each function of the above circuits.

[0028] The mechanical clock 1 has a power generation function using the principle of electromagnetic induction. In the present embodiment, as the ten-ring 31 rotates forward and backward, the permanent magnet 41 rotates forward and backward, and power generation is performed by the current generated in the coil 43 based on the change in the magnetic field due to the movement of the permanent magnet 41, and the speed regulating mechanism 30 functions as part of the generator. The power taken out by the power generation function is used to activate the power supply circuit 60. When the power supply circuit 60 is activated, the control circuit 44 can be driven.

[0029] The rectifier circuit 50 rectifies the current generated in the coil 43 due to the movement of the permanent magnet 41 accompanying the forward and reverse rotational movements of the ten-ring 3I of the speed regulating mechanism 30. The power supply circuit 60 includes, for example, a capacitor, and stores the power for driving the control circuit 44 based on the current rectified by the rectifier circuit 50.

[0030] Referring to FIG. 4, regarding the relationship between the rotation angle of the permanent magnet 41 and the back electromotive voltage, the back electromotive voltage detected by the coil 43 will be described in the period from when the permanent magnet 41 starts rotating in the positive direction (clockwise in FIG. 4) from the 0° position, rotates in the reverse direction (counterclockwise in FIG. 4) due to the elastic force of the hairspring 32, and then rotates in the positive direction again due to the elastic force of the hairspring 32. In the present embodiment, it is preset so that the swing angle of the ten-ring 31 is ±340°. The period from when the permanent magnet 41 reaches the positive maximum angle (+340°) from the rotation angle of 0° and returns to 0° again, and the period from when the permanent magnet 41 reaches the negative maximum angle (-340°) from the rotation angle of 0° and returns to 0° again are defined as a "unit period".

[0031] When the N - pole part 411 of the permanent magnet 41 moves in the direction approaching the first end part 421a of the stator 42, the back - electromotive voltage generated in the coil 43 due to the change in the magnetic field is defined as the "positive" back - electromotive voltage. When the N - pole part 411 of the permanent magnet 41 moves in the direction moving away from the first end part 421a of the stator 42, the back - electromotive voltage generated in the coil 43 due to the change in the magnetic field is defined as the "negative" back - electromotive voltage.

[0032] In this embodiment, the permanent magnet 41 is in a magnetically balanced position at the 0° position. Therefore, at the 0° position, the back - electromotive voltage generated in the coil 43 is 0. The permanent magnet 41 is supplied with power from the power - generating dynamo 11 at the 0° position. Also, while the permanent magnet 41 rotates from the 0° position toward the 180° position, the N - pole part 411 moves in the direction approaching the first end part 421a. Therefore, while the permanent magnet 41 rotates from the 0° position toward the 180° position, a positive back - electromotive voltage is generated in the coil 43.

[0033] 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 voltage generated in the coil 43 is 0. When the permanent magnet 41 rotates from the 180° position toward the 340° position, the N - pole part 411 moves in the direction moving away from the first end part 421a. Therefore, while the permanent magnet 41 rotates from the 180° position toward the 340° position, a negative back - electromotive voltage is generated in the coil 43.

[0034] The angular velocity of the permanent magnet 41 becomes 0 at the 340° position, which is the turning - back position of the reciprocating motion. Therefore, at the 340° position, the back - electromotive voltage generated in the coil 43 is 0. The permanent magnet 41 that has reached the 340° position starts to rotate in the reverse direction due to the elastic force of the hairspring 32. When the permanent magnet 41 rotates from the 340° position toward the 180° position, the N - pole part 411 moves in the direction approaching the first end part 421a. Therefore, while the permanent magnet 41 rotates from the 340° position toward the 180° position, a positive back - electromotive voltage is generated in the coil 43.

[0035] When the permanent magnet 41 rotates from the 180° position toward the 0° position, the N - pole portion 411 moves in a direction away from the first end portion 421a. Therefore, when the permanent magnet 41 rotates from the 180° position toward the 0° position, a negative back - electromotive voltage is generated in the coil 43.

[0036] Power is supplied from the power - generating dynamo 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 portion 421a. Therefore, when the permanent magnet 41 rotates from the 0° position toward the - 180° position, a positive back - electromotive voltage is generated in the coil 43.

[0037] Similar to the permanent magnet 41 being in a magnetically balanced position at the 180° position, the permanent magnet 41 is also in a magnetically balanced position at the - 180° position. At the - 180° position of the permanent magnet 41, the back - electromotive voltage generated in the coil 43 becomes 0. 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 portion 421a. Therefore, while the permanent magnet 41 rotates from the - 180° position toward the - 340° position, a negative back - electromotive voltage is generated in the coil 43.

[0038] The angular velocity of the permanent magnet becomes 0 at the - 340° position, which is the turning - back position of the reciprocating motion. Therefore, at the - 340° position, the back - electromotive voltage generated in the coil 43 becomes 0. The permanent magnet 41 that has reached the - 340° position starts to rotate in the positive direction due to the elastic force of the beard dynamo 32. 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 portion 421a. Therefore, while the permanent magnet 41 rotates from the - 340° position toward the - 180° position, a positive back - electromotive voltage is generated in the coil 43.

[0039] When the permanent magnet 41 rotates from the - 180° position toward the 0° position, the N - pole portion 411 moves in a direction away from the first end portion 421a. Therefore, when the permanent magnet 41 rotates from the - 180° position toward the 0° position, a negative back - electromotive voltage is generated in the coil 43.

[0040] By repeating the operation as described above, when the armature ring 31 (permanent magnet 41) performs a normal forward and reverse rotational motion, the back electromotive voltage shown in FIG. 4 is generated in the coil 43.

[0041] In the present embodiment, the detection circuit 45 detects the detection signal DE according to the zero-crossing point (the point where the positive and negative are switched) of the back electromotive voltage, and sets the detection signal DE detected when the back electromotive voltage switches from negative to positive as the first detection signal DE1, and the detection signal DE detected when the back electromotive voltage switches from positive to negative as the second detection signal DE2. In the timing chart showing the detection timing of the detection signal DE in FIG. 5, the first detection signal DE1 is indicated by a solid line, and the second detection signal DE2 is indicated by a dotted line.

[0042] The step adjustment means 40 determines that the detection signal DE that serves as a reference for the unit cycle in the forward and reverse rotational motion of the armature ring 31 among the first detection signals DE1 is the reference detection signal BP, and performs step adjustment based on the deviation of the detection timing of the reference detection signal BP with respect to the output timing of the reference signal OS.

[0043] The control circuit 44 includes an indeterminate period setting unit 44a. The pace adjustment means 40 sets an indeterminate period, which is a period during which the first detection signal DE1 is not determined to be the reference detection signal BP by the indeterminate period setting unit 44a. The indeterminate period is preset to end at a timing when a predetermined time tm_max preset from the start timing has elapsed. However, the pace adjustment means 40 performs the detection of the first detection signal DE1 and the second detection signal DE2 itself during the indeterminate period. When the first detection signal DE1 is detected during the indeterminate period, the pace adjustment means 40 determines that the first detection signal DE1 is not the reference detection signal BP. Based on the determination, when the first detection signal DE1 is detected before the indeterminate period elapses from the detection timing of the previous reference detection signal BP, the pace adjustment means 40 does not regard the first detection signal DE1 as the reference detection signal BP and determines that the next detected first detection signal DE1 is the reference detection signal BP. When the first detection signal DE1 is not detected before the indeterminate period elapses from the detection timing of the previous reference detection signal BP, the pace adjustment means 40 determines that the first detection signal DE1 detected after the indeterminate period has elapsed is the reference detection signal BP.

[0044] In FIG. 5, the belt-shaped gray area shown superimposed on the waveform of the back electromotive force represents the indeterminate period. In the first cycle, the third cycle, and each cycle after the third cycle, an example is shown where the back electromotive force appears normally without the occurrence of disturbances or the like, and the forward and reverse rotational movements of the tenon ring 31 are performed normally. On the other hand, in the second cycle, an example is shown where the generation of the back electromotive force is disturbed due to the occurrence of disturbances or the like, and an example is shown where the number of zero-crossing points of the back electromotive force in a unit cycle decreases. Since the indeterminate period is a masking period for masking the determination, the timing chart representing the time when the indeterminate period is set in FIG. 5 is represented as "mask".

[0045] The step speed adjustment can be realized by adjusting the braking force of the electromagnetic brake of the braking circuit 80 or the like. The electromagnetic brake outputs in a plurality of consecutive single-pulse forms, and the strength of the braking force can be switched by adjusting the length of a single pulse, the output interval of single pulses, that is, the so-called duty ratio. For example, when the detection timing of the reference detection signal BP is ahead of the output timing of the reference signal OS, the braking force of the electromagnetic brake can be increased so as to slow down the step speed. Note that any configuration can be used as long as the braking control (step speed adjustment) can be performed by the braking circuit 80, and the braking force may be adjusted by a speed adjustment pulse.

[0046] First, the power supply circuit 60 is activated by the power generation caused by the movement of the permanent magnet 41 (Y of S1 in FIG. 6). Thereafter, the first detection signal DE1 is detected (Y of S2 in FIG. 6). The control circuit 44 switches the step speed adjustment control using the first detection signal DE1 detected first in a unit cycle as the reference detection signal BP.

[0047] As shown in FIG. 5, in the first cycle, when the detection timing of the first detection signal DE1 is delayed by time t with respect to the output timing of the reference signal OS output at the 0.5 [s] time point, the control circuit 44 can set the braking force of the electromagnetic brake by the braking circuit 80 to be weakened so that the step speed advances.

[0048] In the present embodiment, a non-determination period is started from the timing when the reference detection signal BP is detected (start timing of the first cycle) (S3 in FIG. 6). Thereafter, after the second detection signal DE2 is detected (Y of S4 in FIG. 6), the first detection signal DE1 is detected (Y of S5 in FIG. 6). Since the first detection signal DE1 in the first cycle is detected within the non-determination period before a predetermined time tm_m has elapsed (N of S6 in FIG. 6), it is not determined as the reference detection signal BP.

[0049] In the present embodiment, in the non-determination period, it is set to end the non-determination period according to the detection timing of the second detection signal DE2 after the detection of the first detection signal DE1 (Y of S7, Y of S8, S9 in FIG. 6).

[0050] Next, since the first detection signal DE1 (Y of S10 in FIG. 6) to be detected next is not in the indeterminate period, the control circuit 44 uses the first detection signal DE1 as a reference detection signal BP (S11 in FIG. 6), and the second cycle starts, and the switching of the step adjustment control is performed (S12 in FIG. 6). In the second cycle, since the detection timing of the first detection signal DE1 substantially coincides with the output timing of the reference signal OS output at the 1.0 [s] time point, the control circuit 44 can be set not to change the braking force of the current electromagnetic brake by the braking circuit 80.

[0051] The step adjustment means 40 starts the indeterminate period from the start timing of the second cycle in which the reference detection signal BP is detected (S3 in FIG. 6).

[0052] As shown in FIG. 5, in the second cycle, due to the disturbance of the reverse electromotive force tendency, the first detection signal DE1 is not detected during the indeterminate period, and the indeterminate period ends at the timing when a predetermined time tm_max has elapsed (N of S5 in FIG. 6, Y of S6, S13).

[0053] The third cycle starts at the detection timing of the first detection signal DE1 (Y of S5 in FIG. 6, N of S7) at the end of the indeterminate period, and the control circuit 44 switches the step adjustment control using the first detection signal DE1 as the reference detection signal BP (S11, S12 in FIG. 6). Hereinafter, in the third cycle in which the reverse electromotive force waveform has no disturbance, the processes of S3, S4, S5, S7 to S12 in FIG. 6 are performed in the same manner as in the first cycle.

[0054] In the present embodiment described above, from the detection signals DE detected a plurality of times in a unit cycle, an appropriate reference detection signal BP serving as a reference for step adjustment can be determined, and the stability of step adjustment can be improved. Further, even when the reverse electromotive force is disturbed due to the influence of external disturbances or the like, an appropriate reference detection signal BP serving as a reference for step adjustment can be determined, so that a desired step adjustment can be continued, and a decrease in step accuracy can be suppressed.

[0055] Note that the length of the predetermined time tm_max can be set according to the tendency of the back electromotive voltage. For example, the length of the predetermined time tm_max can be set to end after the timing at which the first detection signal DE1 detected second in the unit cycle can be detected most slowly when the ten-ring 31 (permanent magnet 41) is operating normally. Thereby, it is possible to suppress erroneously determining that the first detection signal DE1, which is not originally the reference detection signal BP, is the reference detection signal BP. Further, the length of the predetermined time tm_max can also be set to end within less than one unit cycle when the ten-ring 31 is operating normally.

[0056] The start timing of the non-determination period may be set after a predetermined time has elapsed from the detection timing of the reference detection signal BP, or may be the detection timing of the second detection signal DE2 detected immediately after the reference detection signal BP.

[0057] The end timing of the non-determination period may be the detection timing of the first detection signal DEI detected for the first time during the non-determination period, or may be set after a predetermined time has elapsed from the detection timing of the first detection signal DEI detected for the first time during the non-determination period, or after a predetermined time has elapsed from the detection timing of the second detection signal DE2 detected for the second time during the non-determination period.

[0058] A first modification example will be described with reference to FIG. 7. Depending on the detection timing of the first detection signal DE1 or the second detection signal DE2 during the non-determination period, the non-determination period may continue until a predetermined time tm_max.

[0059] For example, if the detection timing of the first detection signal DE1 during the indeterminate period is before a predetermined threshold value t_th from the start of the indeterminate period, the indeterminate period is ended without waiting for a predetermined time tm_max (the left diagram in FIG. 7). If it is after the predetermined threshold value t_th, since the detection timing of the first detection signal DE1 is late and there is a possibility that the reverse electromotive voltage trend is disturbed, the indeterminate period is continued until the predetermined time tm_max elapses (the right diagram in FIG. 7). Note that the predetermined threshold value t_th may be set in advance to be after the detection timing of the first detection signal DE1 detected during the indeterminate period during the normal operation of the ten-ring 31 and before reaching the predetermined time tm_max.

[0060] Whether to continue the indeterminate period until a predetermined time tm_max is not limited to the detection timing of the first detection signal DE1 during the indeterminate period, and may be determined based on the detection timing of the second detection signal DE2 during the indeterminate period.

[0061] A second modification will be described with reference to FIG. 8. As shown in FIG. 8, the braking control may be made different depending on whether the indeterminate period ends before the predetermined time tm_max elapses or ends after continuing until the predetermined time tm_max elapses.

[0062] In the example shown in FIG. 8, the electromagnetic brake DB is turned on based on the timing when the next second detection signal DE2 is detected after the reference detection signal BP is detected.

[0063] In the example shown in FIG. 8, when the indeterminate period ends before the predetermined time tm_max elapses, the electromagnetic brake DB is continued until the next reference detection signal BP is detected.

[0064] On the other hand, when the non-determination period continues until a predetermined time tm_max elapses, the rotation angle of the balance wheel 31 may become extremely small due to disturbances or the like, and normal braking control may not be possible. Therefore, at the timing when the non-determination period ends, the electromagnetic brake DB is turned off. By deliberately turning off the electromagnetic brake DB and increasing the angular velocity of the balance wheel 31, the rotation angle in the next unit cycle can be increased, and the normal operation can be restored.

[0065] When the positive and negative of the reference voltage are reversed, the reference detection signal BP may be detected according to the timing when the back electromotive voltage switches from positive to negative.

[0066] It may be configured to detect only the first detection signal DE1 without detecting the second detection signal DE2, and the start and end timings of the non-determination period may be set based on the detection timing of the first detection signal DE1.

Explanation of Signs

[0067] 1 Mechanical clock, 10 Floor board, 11 Mainspring, 12 Wheel train, 131 Second hand, 20 Escapement mechanism, 21 Gang wheel, 22 Anchor, 30 Regulating mechanism, 31 Balance wheel, 311 Balance rim, 32 Hairspring, 34 Hairspring holder, 40 Pace adjustment 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 Non-determination period setting part, 45 Detection circuit, 47 Dividing circuit, 48 Oscillation circuit, 50 Rectifying circuit, 60 Power supply circuit, 70 Crystal oscillator, 80 Braking circuit.

Claims

1. A ten-ring that rotates forward and backward, A permanent magnet that rotates forward and backward along with the forward and backward rotation of the ten-ring, A coil in which a back electromotive voltage is generated according to the forward and backward rotation of the permanent magnet, A detection circuit that detects a detection signal according to either one of the timings when the back electromotive voltage switches from positive to negative and from negative to positive, A step adjustment means that performs step adjustment based on the detection timing of a reference detection signal that is a reference for a unit cycle in the forward and backward rotation of the ten-ring among the detection signals, having, The step adjustment means, when the detection signal is detected before a predetermined time has elapsed from the detection timing of the previous reference detection signal, sets the next detected detection signal as the reference detection signal, A mechanical clock.

2. The step adjustment means, when the detection signal is not detected before the predetermined time has elapsed from the detection timing of the previous reference detection signal, sets the detection signal detected after the predetermined time has elapsed as the reference detection signal, The mechanical clock according to Claim 1.

3. The step adjustment means starts a non-determination period in which a determination that the detection signal is the reference detection signal is not made, based on the detection timing of the reference detection signal, The mechanical clock according to Claim 1 or 2.

4. when the detection signal is detected during the non-determination period, ends the non-determination period before the predetermined time has elapsed, The mechanical clock according to Claim 3.

5. The detection circuit detects a first detection signal that is the detection signal according to either one of the timings when the back electromotive voltage switches from positive to negative and from negative to positive, and detects a second detection signal according to either the other one of the timings when the back electromotive voltage switches from positive to negative and from negative to positive, The step adjustment means, when the second detection signal is detected twice during the non-determination period, ends the non-determination period before the predetermined time has elapsed, The mechanical clock according to Claim 3.

6. The step adjustment means, when the detection timing of the detection signal detected during the non-determination period is later than a predetermined threshold value, waits for the predetermined time to elapse and then ends the non-determination period, The mechanical clock according to Claim 3.

7. The detection circuit detects a first detection signal, which is the detection signal, in response to either one of the timings when the back electromotive voltage switches from positive to negative and from negative to positive, and detects a second detection signal in response to the other timing when the back electromotive voltage switches from positive to negative and from negative to positive. The pace adjustment means When the detection timing of the second detection signal detected during the non-determination period is later than a predetermined threshold value, the non-determination period is ended after waiting for the elapse of the predetermined time. The mechanical timepiece according to claim 3.

8. When the non-determination period ends by elapsing the predetermined time, the pace adjustment means performs control to increase the pace. The mechanical timepiece according to claim 3.

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