Mechanical timepiece

Abstract

To provide a mechanical timepiece 1 improving rate accuracy by appropriately setting timing to generate braking force.SOLUTION: A mechanical timepiece 1 comprises: a mainspring 11; a balance 30 including a balance wheel 31 driven by power from the mainspring 11, and a balance spring 32 elastically deformed so as to rotationally move the balance wheel 31 forward and backward; a permanent magnet 41 with two magnet poles rotationally moving forward and backward as the balance wheel 31 rotationally moves forward and backward; a coil 43; and rate adjustment means 40 for adjusting the rate by performing braking control that generates braking force for braking the permanent magnet 41. A maximum displacement angle of the permanent magnet 41 in the forward / backward rotational movement is larger than 180°, and the rate adjustment means 40 sets timing to generate the braking force based on a detection voltage generated in the coil 43 by the forward / backward rotational movement of the permanent magnet 41, and performs the braking control based on the set timing.SELECTED DRAWING: Figure 11

Description

[Technical field]

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

[0002] Patent document 1 discloses a timepiece equipped with a mechanical oscillator that allows the speed-regulating system to be self-powered by electrical energy drawn from the mechanical oscillator. Patent document 1 also discloses reducing the oscillation frequency of the resonator by a braking pulse. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-113548 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a watch capable of self-powering, a large amount of electricity can be generated by increasing the oscillation angle of the balance wheel. However, in a watch with a large oscillation angle of the balance wheel, it is necessary to devise a timing for adjusting the rate by using a braking force such as a braking pulse.

[0005] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a mechanical timepiece that improves the rate accuracy by appropriately setting the timing for generating a braking force. [Means for solving the problem]

[0006] (1) A mechanical timepiece comprising: a power source; a regulating mechanism including a balance wheel driven by power from the 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 forward and reverse directions in accordance with the forward and reverse rotational movements of the balance wheel; a coil; and rate adjustment means that adjusts the rate by performing braking control to generate a braking force that brakes the permanent magnet, wherein the maximum displacement angle in the forward and reverse rotational movements of the permanent magnet is greater than 180°, and the rate adjustment means sets the timing for generating the braking force based on a detection voltage generated in the coil by the forward and reverse rotational movements of the permanent magnet, and performs the braking control based on the set timing.

[0007] (2) In the mechanical timepiece according to (1), the rate adjustment means sets the timing for generating the braking force based on the period of the detected voltage.

[0008] (3) In the mechanical timepiece of (1) or (2), the rate adjustment means obtains a first period, which is either positive or negative of the detected voltage, and a second period, which is either positive or negative and appears after the first period, and sets the timing for generating the braking force based on the length relationship between the first period and the second period.

[0009] (4) A mechanical watch according to any one of (1) to (3), further comprising a zero-cross detection circuit that detects zero-cross points where the detection voltage switches between positive and negative, and the rate adjustment means sets the timing for generating the braking force based on the detection interval between a plurality of zero-cross points detected by the zero-cross detection circuit.

[0010] (5) In (4), the rate adjustment means obtains a first period which is the detection interval between a first zero cross point detected when the detection voltage switches from negative to positive and a second zero cross point detected immediately thereafter which is detected when the detection voltage switches from positive to negative, and a second period which is the detection interval between a third zero cross point detected immediately after the second zero cross point which is detected when the detection voltage switches from negative to positive, and a fourth zero cross point detected immediately thereafter which is detected when the detection voltage switches from positive to negative, and sets the timing for generating the braking force based on the length relationship between the first period and the second period.

[0011] (6) In the mechanical timepiece according to (3) or (5), the rate adjustment means sets the start point of the period corresponding to the shorter of the first period and the second period as the reference timing for generating the braking force.

[0012] (7) A mechanical watch according to any one of (1) to (6), further comprising a zero-cross detection circuit for detecting a zero-cross point where the detection voltage switches between positive and negative, and wherein the rate adjustment means, when a deviation amount of the detection timing of the zero-cross point from the output timing of a reference signal output from a reference signal source during the braking control is equal to or greater than a predetermined value, sets a timing for generating the braking force and resumes the braking control based on the set timing.

[0013] (8) A mechanical timepiece according to any one of (1) to (7), further comprising a zero-cross detection circuit that detects a zero-cross point where the detection voltage switches between positive and negative, and the rate adjustment means sets the timing for generating the braking force after the balance wheel, which is in a stopped state, starts its forward and reverse rotational motion and the detection interval of the zero-cross point becomes equal to or less than a certain value.

[0014] (9) In the mechanical timepiece according to (3) or (5), the rate adjustment means obtains the relationship between the first period and the second period at least twice, and if the current relationship is different from the previous relationship, continues obtaining the relationship.

[0015] (10) The mechanical timepiece according to any one of (1) to (9), wherein the rate adjustment means generates a weak braking force weaker than the braking force during a period before the timing for generating the braking force is set.

[0016] (11) In any one of (1) to (10), the rate adjusting means includes a braking circuit that generates an electromagnetic brake for braking the permanent magnet by shorting the coil.

[0017] (12) A mechanical timepiece according to any one of (1) to (11), comprising a first end provided along the outer periphery of the permanent magnet, and a second end provided along the outer periphery of the permanent magnet and positioned opposite the first end via the permanent magnet, the mechanical timepiece having a soft magnetic core forming a magnetic circuit together with the coil, the permanent magnet being positioned such that the magnetization direction faces the first end or the second end when the hairspring is in a neutral position of its elastic deformation.

[0018] (13) A mechanical timepiece according to (12), wherein the balance wheel is in a power supply position where power is supplied from the power source when the hairspring is in the neutral position, and the permanent magnet is arranged so that the detection voltages detected during the period from the power supply position until the balance wheel rotates 180° in the forward or reverse direction have the same polarity. Effect of the Invention

[0019] According to the above aspects (1) to (13) of the present invention, it is possible to provide a mechanical timepiece with improved rate accuracy. [Brief description of the drawings]

[0020] [Figure 1]FIG. 2 is a perspective view showing the base plate and each member assembled thereto according to the present embodiment. [Diagram 2] FIG. 2 is a perspective view showing a mechanism for transmitting power and its surroundings in the embodiment. [Diagram 3] 2 is an exploded perspective view showing the speed regulating mechanism and its peripheral members disassembled from the main plate in the embodiment. FIG. [Figure 4] 2A and 2B are a plan view showing a soft magnetic core and its periphery according to the embodiment, and an enlarged plan view showing a part of the soft magnetic core and its periphery in an enlarged manner. [Diagram 5] 1 is a block diagram showing the overall configuration of a mechanical timepiece according to an embodiment of the present invention. [Figure 6] 5A and 5B are diagrams illustrating the relationship between the operation of the balance wheel and the back electromotive voltage generated in the coil in the embodiment. [Figure 7] FIG. 2 is a circuit diagram showing an example of a circuit included in a mechanical timepiece. [Figure 8] 4 is a timing chart showing an example of braking control. [Figure 9] 4 shows the back electromotive voltage detected in the coil as the permanent magnet of this embodiment rotates. [Figure 10A] 5 is a diagram for explaining an example of setting the start timing of an electromagnetic brake in the present embodiment. FIG. [Figure 10B] 5 is a diagram for explaining an example of setting the start timing of an electromagnetic brake in the present embodiment. FIG. [Figure 11] 5 is a flowchart showing an example of setting control of the start timing of an electromagnetic brake in the present embodiment. [Figure 12] 4 is a flowchart showing an example of braking control in the present embodiment. [Figure 13] 11 is a diagram illustrating detection of a zero-cross point according to the magnitude of the oscillation angle of a balance wheel. FIG. [Figure 14] 10 is a flowchart showing setting control of the start timing of an electromagnetic brake in a first modified example of the embodiment. [Figure 15] FIG. 11 is a diagram for explaining an example of setting the timing for starting an electromagnetic brake in a second modified example of the embodiment. [Figure 16] 10 is a flowchart showing an example of setting control of the start timing of an electromagnetic brake in a second modified example of the embodiment. [Figure 17] FIG. 13 is a diagram for explaining an example of setting the timing for starting an electromagnetic brake in a third modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, an embodiment of the present invention (hereinafter, referred to as the present embodiment) will be described in detail with reference to the drawings.

[0022] [Overall configuration overview] First, an overview of the overall configuration of a mechanical timepiece 1 according to this embodiment will be described with reference to Figs. 1 to 5. Fig. 1 is a perspective view showing the main plate of this embodiment and the various components incorporated therein. Fig. 2 is a perspective view showing the mechanism for transmitting power in this embodiment and its periphery. Fig. 3 is an exploded perspective view showing the speed regulating mechanism and its peripheral components in this embodiment disassembled from the main plate. Fig. 4 is a plan view showing the soft magnetic core and its periphery in this embodiment, and an enlarged plan view showing an enlarged portion of the soft magnetic core. Fig. 5 is a block diagram showing the overall configuration of a mechanical timepiece according to this embodiment. Figs. 1 to 3 show the mechanical timepiece 1 as viewed from the back side. The back side is the side in the thickness direction of the mechanical timepiece 1 where the back cover of the exterior case is disposed.

[0023] The mechanical timepiece 1 is a timepiece that uses a power spring 11 as its power source, and controls the movement of the power spring 11 with an escapement mechanism 20 and a speed regulator mechanism 30, while also driving the hands. The mechanical timepiece 1 is configured by housing a main plate 10, into which the mechanisms that drive the hands are assembled, in an exterior case. Note that in this embodiment, the exterior case is not shown in the figure. Also, the crown that is placed on the side of the exterior case is not shown in the figure. The crown is attached to the end of the winding stem 2 shown in FIG. 1.

[0024] [Overall configuration: Drive mechanism configuration] An overview of the drive mechanism of the mechanical timepiece 1 will be described. In this embodiment, the mechanism including the power spring 11, which is the power source, the wheel train 12, and the hand shaft 13 is referred to as the "drive mechanism." Note that in Fig. 2, only the second hand 131 of the hands is shown. The drive mechanism shown in Fig. 2 is one example, and is not limited to this, and may include gears and the like other than those shown in the figure.

[0025] The power spring 11 is made of a metal band-shaped body and is housed in a barrel 110 having a plurality of teeth formed on its outer circumference. The barrel 110 is disk-shaped and has a cavity formed therein for housing the power spring 11. The inner end of the power spring 11 is fixed to a barrel stem (not shown) which is a rotating shaft provided at the center of the barrel 110, and the outer end is fixed to the inner surface of the barrel 110. When the crown is rotated by a user's operation, the winding stem 2 rotates. The power spring 11 is wound up in accordance with the rotation of the winding stem 2. The wound power spring 11 is unwound by its elastic force. The operation of the power spring 11 at this time causes the barrel 110 to rotate.

[0026] The wheel train 12 includes at least a center wheel 122, a third wheel 123, and a fourth wheel 124. The center wheel 122 includes a pinion that meshes with a plurality of teeth formed on the barrel 110 that functions as the first wheel, a rotating shaft, and a plurality of teeth, and transmits the rotation of the barrel 110 to the third wheel 123. The rotating shaft of the center wheel 122 is the pointer shaft of the minute hand (not shown). The third wheel 123 includes a pinion that meshes with a plurality of teeth of the center wheel 122, a rotating shaft, and a plurality of teeth, and transmits the rotation of the center wheel 122 to the fourth wheel 124. The fourth wheel 124 includes a pinion that meshes with a plurality of teeth of the third wheel 123, a rotating shaft, and a plurality of teeth, and transmits the rotation of the third wheel 123 to the escapement mechanism 20. As shown in FIG. 2, the rotating shaft of the fourth wheel 124 is the pointer shaft 13 of the second hand 131.

[0027] [Overview of the overall configuration: Overview of the configuration of the escapement mechanism 20 and the speed regulator mechanism 30, and their operation] Next, the escapement mechanism 20 and the regulating mechanism 30 will be described. Power from the power spring 11 is transmitted to the escapement mechanism 20 and the regulating mechanism 30 through the wheel train 12. The escapement mechanism 20 is configured to include an escape wheel 21 and an anchor 22. The regulating mechanism 30 is configured to include a balance wheel 31 and a hairspring 32. The regulating mechanism 30 is sometimes called a balance.

[0028] The escape wheel 21 is a component that receives the rhythm of the regulating mechanism 30 from the pallet fork 22 by meshing with the pallet fork 22 and converts it into regular reciprocating motion. The escape wheel 21 includes a pinion that meshes with multiple teeth of the second wheel & pinion 124, a rotating shaft, and multiple teeth. As shown in Figure 2, the multiple teeth of the escape wheel 21 are formed at wider intervals in the circumferential direction than the teeth of each gear of the train wheel 12.

[0029] The pallet fork 22 rotates forward and backward around the pallet fork 221 shown in Fig. 4 as a rotation axis. The pallet fork 22 extends from the pallet fork 221 toward the center of the balance wheel 31 (balance fork 311), and has a rod portion 222 that strikes an impulse jewel (not shown) that rotates together with the balance fork 311. The impulse jewel is fixed to the balance fork 311.

[0030] Furthermore, the pallet fork 22 has a first arm 223 to which is attached a recessed prong 223a that strikes against multiple teeth of the escape wheel 21, and a second arm 224 to which is attached a projecting prong 224a that extends in the opposite direction to the first arm 223 and strikes against multiple teeth of the escape wheel 21. The recessed prong 223a and the projecting prong 224a may be made of a stone such as sapphire.

[0031] The balance wheel 31 rotates in both forward and reverse directions around the balance arbour 311 by the power transmitted by the wheel train 12. In the following description, the forward motion of the forward and reverse rotational motions may be referred to as "forward rotation" and the reverse motion as "reverse rotation".

[0032] As shown in Fig. 3, it is preferable that the balance wheel 31 has a circular outer shape. However, the shape of the balance wheel 31 shown in Fig. 3 is only an example, and the shape of the balance wheel 31 is arbitrary. The balance arbour 311 is supported by a support member 33 shown in Fig. 3.

[0033] The hairspring 32 expands and contracts (elastically deforms) so as to rotate the balance wheel 31 in forward and reverse directions. The hairspring 32 is spiral-shaped, with its inner end fixed to the balance axle 311 and its outer end fixed to a hairspring holder 34. The hairspring holder 34 is fixed to the main plate 10 together with the support member 33. The hairspring holder 34 is sandwiched between the support member 33 and a frame member 35, as shown in FIG. 3.

[0034] The escape wheel 21 rotates with the rotation of the fourth wheel 124. When the escape wheel 21 rotates, it collides with the pallet 223a of the pallet fork 22, and the pallet fork 22 rotates around the pallet fork arbor 221. The shaft part 222 of the rotating pallet fork 22 collides with the impulse jewel fixed to the balance arbor 311, causing the balance wheel 31 to rotate. When the balance wheel 31 rotates, the pallet 224a of the pallet fork 22 collides with the escape wheel 21, stopping the escape wheel 21. When the balance wheel 31 rotates in the opposite direction due to the restoring force of the hairspring 32, the pallet 223a of the pallet fork 22 is released, and the escape wheel 21 rotates again. As described later, the balance wheel 31 is designed to perform one reciprocating motion in two seconds, so that the escape wheel 21 performs one step motion per second.

[0035] In this embodiment, a resin material with a low Young's modulus is used as the material for the hairspring 32. This makes it possible to achieve slower vibration of the balance wheel 31 than when it is made of a metal material. If one were to try to achieve slower vibration with a metal hairspring, it would be necessary to reduce the cross-sectional area of ​​the hairspring 32 to a level that makes it difficult to process, or to increase the length of the hairspring to a level that makes it difficult to handle.

[0036] In this embodiment, a resin having a Young's modulus of about 5 [GPa] is used as the material of the hairspring 32. Specifically, polyester is used as the material of the hairspring 32. The hairspring 32 made of a resin material may be manufactured by, for example, laser processing. The Young's modulus of a general metal hairspring is about 200 [GPa]. The Young's modulus shown here is an example, and the Young's modulus of the hairspring 32 may be 20 [GPa] or less. That is, the Young's modulus of the hairspring 32 may be 1 / 10 or less of the Young's modulus of the metal hairspring. More preferably, the Young's modulus of the hairspring 32 may be 10 [GPa] or less. That is, the Young's modulus of the hairspring 32 may be 1 / 20 or less of the Young's modulus of the metal hairspring. Also, the Young's modulus may be 20 [GPa] or less, and the hairspring 3 may be made of a material such as paper or wood.

[0037] In this embodiment, the rotation angle [deg] of the balance wheel 31 and the permanent magnet 41 in a state where the hairspring 32 is in a neutral position of elastic deformation is set to 0°. The neutral position of elastic deformation of the hairspring 32 is, in other words, a position where the hairspring 32 is at its natural length. Power is supplied from the power spring 11 to the balance wheel 31 in a state where the hairspring 32 is in a neutral position of elastic deformation. That is, the balance wheel 31 and the permanent magnet 41 are in a power supply position where power is supplied from the power spring 11 at a rotation angle of 0°. As will be described later, in this embodiment, the permanent magnet 41 is in a magnetically balanced position at a rotation angle of 0°.

[0038] In this embodiment, the balance wheel 31 is designed to drive within a rotation angle range of 340° to -340°. Therefore, the permanent magnet 41 also drives within a rotation angle range of 340° to -340°. However, this is only an example, and the movement range of the balance wheel 31 is preferably wider than the range of rotation angles of 180° to -180°. By increasing the movement range of the balance wheel 31 to a certain extent in this way, it is possible to achieve a slow vibration speed of the balance wheel 31.

[0039] As described above, the regulating mechanism 30 repeatedly rotates the balance wheel 31 in forward and reverse directions (reciprocating motion) at a constant cycle by the expansion and contraction motion of the hairspring 32. The escapement mechanism 20 continues to apply a force for reciprocating motion to the balance wheel 31. With this configuration and operation, the hands such as the second hand 131 are driven.

[0040] [Overall Configuration: Configuration of the Rate Adjustment Means 40] Next, a description will be given of the configuration of the rate adjustment means 40. The mechanical timepiece 1 according to this embodiment includes the rate adjustment means 40 in addition to the drive mechanism, the escapement mechanism 20, and the speed regulation mechanism 30.

[0041] The rate adjustment means 40 includes a permanent magnet 41, a soft magnetic core 42 (sometimes called a stator), a coil 43, and various circuits (see FIG. 5). The rate adjustment means 40 adjusts the rate based on a detection signal detected based on the forward and reverse rotational motion of the permanent magnet 41 and a reference frequency of a crystal oscillator 70, which is a reference signal source. In this embodiment, as shown in FIG. 8, which will be described later, the output period of the reference signal OS is set to an output period ts having a predetermined width. Note that, in this embodiment, the crystal oscillator 70 is used as the reference signal source to achieve high frequency accuracy, but the present invention is not limited to this, and for example, a CR oscillator composed of a capacitor and a resistor may be used.

[0042] Although not shown in the drawings, the coil 43 may be arranged so as to overlap an inner frame provided inside the outer case in a plan view. Alternatively, a notch may be formed in a part of the inner frame in the circumferential direction, and the coil 43 may be arranged within the notch.

[0043] The permanent magnet 41 is a bipolar magnetized disk-shaped rotating body, and is magnetized with an N pole and an S pole in the radial direction.

[0044] The permanent magnet 41 is attached to the balance stem 311, which is the rotation axis of the balance wheel 31, and is provided so as to perform forward and reverse rotational motion in accordance with the forward and reverse rotational motion of the balance wheel 31 (balance stem 311). In other words, the permanent magnet 41 performs forward and reverse rotational motion together with the balance wheel 31 so that its rotation angle is the same as the rotation angle of the balance wheel 31. The permanent magnet 41 may be fixed to the balance stem 311 by press-fitting, adhesive, or the like.

[0045] The permanent magnet 41 is preferably an isotropic magnet with its easy axis of magnetization pointing in a random direction. The permanent magnet 41 is preferably magnetized by applying a magnetic field to it using a Helmholtz coil or the like while attached to the balance shaft 311. By employing such a magnetization method, the magnetization direction of the permanent magnet 41 can be accurately aligned.

[0046] 4, the soft magnetic core 42 is made of a soft magnetic material and has a first magnetic portion 421 including a first end portion 421a provided along the outer periphery of the permanent magnet 41, and a second magnetic portion 422 including a second end portion 422a provided along the outer periphery of the permanent magnet 41, and forms a magnetic circuit together with the coil 43. The first end portion 421a and the second end portion 422a are both shaped to have a semicircular inner circumferential surface, and are disposed opposite each other with the permanent magnet 41 interposed therebetween.

[0047] In this embodiment, when the hairspring 32 is in a neutral position of elastic deformation, the permanent magnet 41 has the N-pole portion 411 disposed on the second magnetic portion 422 side and the S-pole portion 412 disposed on the first magnetic portion 421 side (see the enlarged view in FIG. 4). Note that the arrangement of the N-pole portion 411 and the S-pole portion 412 may be reversed, but in that case, the winding direction of the coil 43 needs to be reversed from that of this embodiment.

[0048] 3, the soft magnetic core 42 is fixed to the support member 33 by a pipe 33a and a screw 33b, which are fasteners. With this configuration, the soft magnetic core 42 is attached to the base plate 10 together with the support member 33.

[0049] Of the components assembled to the main plate 10, those components such as the support member 33, balance holder 34, frame member 35, balance spring 32, and balance wheel 31 located close to the permanent magnet 41, excluding the soft magnetic core 42, are desirably made of non-magnetic materials so as not to affect the forward and reverse rotational motion of the regulating mechanism 30 or the back electromotive force generated by the coil 43 described later.

[0050] 4, the soft magnetic core 42 includes a first welded portion 423 which is a first separation portion that separates the magnetic coupling between the first end 421a and the second end 422a, and a second welded portion 424 which is a second separation portion that separates the magnetic coupling between the first end 421a and the second end 422a and is disposed opposite the first welded portion 423 via the permanent magnet 41. The first welded portion 423 and the second welded portion 424 are preferably formed in a gap that physically separates the first end 421a and the second end 422a.

[0051] The permanent magnet 41 is in a magnetically balanced position when the magnetization direction is perpendicular to the opposing direction of the first welded portion 423 and the second welded portion 424. In this embodiment, the magnetically balanced position of the permanent magnet 41 is set to a rotation angle of 0°. In this position, the holding torque of the permanent magnet 41 is approximately 0. The opposing direction of the first welded portion 423 and the second welded portion 424 is the direction in which a straight line connecting the first welded portion 423 and the second welded portion 424 extends, as shown in FIG. 4. As shown in FIG. 4, in this embodiment, notches are formed on the inner circumferential surfaces of the first end portion 421a and the second end portion 422a of the soft magnetic core 42. Specifically, a notch n11 and a notch n12 are formed in the first end portion 421a. In addition, a notch n21 is formed in the second end portion 422a so as to face the notch n11 through the permanent magnet 41, and a notch n22 is formed so as to face the notch n12 through the permanent magnet 41. By forming the notches in this manner, the magnetic influence on the permanent magnet 41 by the soft magnetic core 42 is reduced.

[0052] In the present embodiment, as shown in FIG. 4, an example is shown in which the first end 421a and the second end 422a of the soft magnetic core 42 are integrated via the first welded portion 423 and the second welded portion 424, but this is not limited to the above. For example, the first end 421a and the second end 422a may not have the first welded portion 423 and the second welded portion 424, and the first end 421a and the second end 422a may be magnetically separated via a gap. In addition, the present embodiment is not limited to a case in which the magnetic coupling is completely separated. For example, the first end 421a and the second end 422a may be physically connected via a narrowed portion that is a separating portion.

[0053] As shown in Fig. 5, the rate adjustment means 40 includes a control circuit 44, a zero-cross detection circuit 45, a speed control pulse output circuit 46, a frequency division circuit 47, an oscillation circuit 48, and a braking circuit 80. The permanent magnet 41, the soft magnetic core 42, and the coil 43 described above are omitted from Fig. 5. The configuration of the rate adjustment means 40 shown in Fig. 5 is one example. The rate adjustment means 40 does not need to have each circuit shown in Fig. 5 independently, and it is sufficient if it can realize each function described below.

[0054] The control circuit 44 is a circuit that controls the operation of each circuit included in the rate adjusting means 40. In particular, the control circuit 44 performs braking control, which controls the braking force for braking the permanent magnet 41, by controlling the speed control pulse output circuit 46 and the braking circuit 80, as described later.

[0055] The oscillation circuit 48 outputs a predetermined oscillation signal based on the frequency of the crystal oscillator 70. The frequency of the crystal oscillator 70 is 32768 [Hz]. The frequency divider circuit 47 divides the frequency of the oscillation signal output from the oscillation circuit 48. The frequency divider circuit 47 divides the frequency of the oscillation signal based on the crystal oscillator 70 to generate a reference signal OS that is output approximately every 1000 [ms]. However, this is not limited, and the reference signal OS may be output every 2000 [ms] or every 3000 [ms]. In other words, the reference signal OS may be output every second. Furthermore, this is not limited, and the reference signal OS may be output corresponding to the period of the speed-governing mechanism 30.

[0056] The zero-cross detection circuit 45 outputs the detection signal DE based on the voltage waveform generated in the coil 43 by the motion of the permanent magnet 41. The detection signal DE output from the zero-cross detection circuit 45 may be input to the control circuit 44. In this embodiment, rotation detection may be performed based on the detection timing of the detection signal DE. The zero-cross detection circuit 45 may be capable of outputting the detection signal DE, which is a pulse signal synchronized with the timing at which the back electromotive force becomes 0. The zero-cross detection circuit 45 may output the detection signal DE when a back electromotive force equal to or greater than a predetermined threshold Vth occurs. The predetermined threshold Vth is a value near 0 [V], and for example, the positive threshold Vth may be +10 [mV] and the negative threshold Vth may be -10 [mV]. Note that noise may be generated instantaneously near the threshold Vth of 0 [V] due to an external factor such as an impact. In order to avoid erroneous detection due to such noise, for example, the timing of determining the zero cross for rotation detection may be the timing at which the detection signal DE is detected a predetermined number of times, which is equal to or greater than two times. However, this is not limiting, and may be determined appropriately based on the output interval of the detection signal DE, the number of times the detection signal DE is continuously detected, the accumulated number of times the detection signal DE is detected, and the like.

[0057] The speed control pulse output circuit 46 outputs a speed control pulse based on the reference signal generated by the frequency divider circuit 47 and the detection signal DE detected by the zero cross detection circuit 45. Specifically, the detection timing of the detection signal DE detected by the zero cross detection circuit 45 is compared with the output timing of the reference signal of about 1000 [Hz], and if there is a discrepancy between these timings, the speed control pulse output circuit 46 outputs a speed control pulse so that the period at which the detection signal DE is detected approaches 1000 [ms] (=1 second).

[0058] The speed control pulse is output by energizing the coil 43. Therefore, when the cycle in which the detection signal DE is detected is faster than the reference signal, the speed control pulse output circuit 46 energizes the coil 43 so that a torque acts in a direction that slows down the movement of the permanent magnet 41, and when the cycle in which the detection signal DE is detected is slower than the reference signal, the speed control pulse output circuit 46 energizes the coil 43 so that a torque acts in a direction that speeds up the movement of the permanent magnet 41. The speed control pulse output when the coil 43 is energized so that a torque acts in a direction that slows down the movement of the permanent magnet 41 becomes a braking force that brakes the movement of the permanent magnet 41.

[0059] The speed regulating pulse output circuit 46 may be configured to be capable of outputting a plurality of speed regulating pulses having different output periods (pulse widths) from one another. The speed regulating pulse output circuit 46 may be configured to be capable of outputting a plurality of speed regulating pulses having different output voltages from one another.

[0060] [Overall configuration: Governor mechanism 30 as a generator] The mechanical timepiece 1 has a power generation function that uses the principle of electromagnetic induction. In this embodiment, the speed-regulating mechanism 30 functions as part of the generator. Specifically, the permanent magnet 41 rotates forward and backward in accordance with the forward and reverse rotation of the balance wheel 31, and power is generated by the current generated in the coil 43 based on the change in the magnetic field caused by the movement of the permanent magnet 41. The power extracted by this operating principle is used to start the power supply circuit 60. The control circuit 44 can be driven by starting the power supply circuit 60. Because this configuration is adopted, in this embodiment, the control circuit 44 can be driven without providing a separate power source such as a battery.

[0061] The rectifier circuit 50 rectifies the current generated in the coil 43 by the motion of the permanent magnet 41 associated with the forward and reverse rotational motions of the balance wheel of the speed regulating mechanism 30. The power supply circuit 60 is a circuit including, for example, a capacitor, and stores power for driving the control circuit 44 based on the current rectified by the rectifier circuit 50.

[0062] [Braking control overview] Next, an overview of braking control will be described with reference to Figs. 6 to 8. Fig. 6 is a diagram for explaining the relationship between the operation of the balance wheel and the back electromotive force generated in the coil in this embodiment. In the graph in the upper part of Fig. 6, the vertical axis is the angular velocity [rad / s] of the balance wheel 31, and the horizontal axis is the measurement time [s]. In the graph in the middle part of Fig. 6, the vertical axis is the rotation angle [deg] of the balance wheel 31, and the horizontal axis is the measurement time [s]. In the graph in the lower part of Fig. 6, the vertical axis is the back electromotive force [V] generated in the coil 43, and the horizontal axis is the measurement time [s]. Moreover, each graph shown in Fig. 6 shows an example in which the movement of the balance wheel 31 (permanent magnet 41) was measured for 4 seconds.

[0063] FIG. 7 is a circuit diagram showing an example of a circuit that a mechanical timepiece has. FIG. 8 is a timing chart showing an example of braking control. The upper part of FIG. 8 shows a voltage waveform generated in the coil 43 when braking control is performed. During the period when the electromagnetic brake DB is applied, the coil 43 is short-circuited, so no back electromotive voltage is detected. In the upper part of FIG. 8, the back electromotive voltage waveforms are all shown in solid lines for the sake of visibility, but the back electromotive voltage is zero during the period when the electromagnetic brake DB is applied. The lower part of FIG. 8 shows the detection timing of the detection signal DE, the output timing of the reference signal OS, and the application timing of the electromagnetic brake. The electromagnetic brake is a braking force obtained by shorting the first terminal O1 and the second terminal O2 of the coil 43 to create a closed loop state, and generating 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, and by induced electromotive force.

[0064] In this embodiment, the braking circuit 80 applies the electromagnetic brake DB to control the movement of the permanent magnet 41, thereby controlling the movement of the balance wheel 31 and adjusting the rate. In Fig. 6, the timing for applying the electromagnetic brake DB (rate adjustment timing) is indicated by a band-shaped area. It is preferable that the electromagnetic brake DB be applied while avoiding a period when power generation is likely to be obtained. In particular, it is preferable that the electromagnetic brake DB be applied while avoiding a period when the permanent magnet 41 rotates in the forward direction from a rotation angle of 0° to 180° and a period when the permanent magnet 41 rotates in the reverse direction from 0° to -180°, which are periods that include the peak of power generation.

[0065] Next, the circuit configuration of this embodiment will be described with reference to FIG.

[0066] As shown in FIG. 7, transistors TP1 and TP2 are connected to the first terminal O1 and the second terminal O2 of the coil 43, respectively. The back electromotive voltage generated in the coil 43 is input to the transistors TP1 and TP2, and the zero-cross detection circuit 45 detects a detection signal based on the input. By turning on the transistor TP1 or TP2 at a predetermined timing, the induced voltage generated at the first terminal O1 and the second terminal O2 corresponding to the transistor can be extracted as a detection signal, which is a voltage signal. Specifically, when a positive back electromotive voltage is detected, the transistor TP1 is turned off and the transistor TP2 is turned on. On the other hand, when a negative back electromotive voltage is detected, the transistor TP1 is turned on and the transistor TP2 is turned off.

[0067] Moreover, the transistors P11 and P12 are connected to the first terminal O1 of the coil 43, and the transistors P21 and P22 are connected to the second terminal O2 of the coil 43. The transistors P11, P12, P21, and P22 are ON / OFF controlled by a speed control pulse from the speed control pulse output circuit 46. During power generation, the gate terminals of the transistors P11, P12, P21, and P22 are turned OFF. At this time, it is preferable that the braking circuit 80 is in a state where it does not generate a braking force. That is, it is preferable that the transistors DB1 and DB2 described below are turned OFF. In this state, the rectifier circuit 50 is formed by the transistors TP1 and TP2 and the diode D. As the permanent magnet 41 rotates forward and backward, a current flows through the coil 43 and the capacitor C is charged. When a certain amount of charge is stored in the capacitor C, the power supply circuit 60 starts up. When the power supply circuit 60 is started, the control circuit 44 is started, and the control circuit 44 controls each circuit included in the rate adjusting means 40.

[0068] Furthermore, the transistor DB1 is connected to the first terminal O1 of the coil 43, and the transistor DB2 is connected to the second terminal O2 of the coil 43. The transistors DB1 and DB2 configure a braking circuit 80 shown in Fig. 5. The braking circuit 80 is a circuit that generates a braking force that reduces the vibration frequency of the permanent magnet 41 by shorting the first terminal O1 and the second terminal O2. Note that, in Fig. 5, the braking circuit 80 is shown as being included as a part of the rate adjusting means 40, but is not limited to this.

[0069] In the example shown in the lower part of Fig. 8, the electromagnetic brake DB is applied for an application period b1 when a time tb1 has elapsed since the detection signal DE was detected. The electromagnetic brake DB is applied every time the detection signal DE is detected. Note that Fig. 8 shows an example in which the reference signal OS is set on a one-step (one second) basis, but this is not limiting. That is, the reference signal OS may be output on a two-step (two seconds) or three-step (three seconds) basis. In this case, it is preferable to generate a reference signal OS that is output approximately every 2000 ms or approximately every 3000 ms by dividing the frequency of the oscillation signal based on the crystal oscillator 70.

[0070] 5 and 7 is not essential. That is, the rate adjustment may be achieved only by the electromagnetic brake DB of the braking circuit 80.

[0071] [Relationship between rotation angle of permanent magnet 41 and back electromotive force] Further, the relationship between the rotation angle of the permanent magnet 41 and the back electromotive voltage will be described in detail with reference to Fig. 9. Fig. 9 shows the back electromotive voltage detected by the coil as the permanent magnet of this embodiment rotates. The relationship between the rotation angle of the permanent magnet 41 and the back electromotive voltage is the same as the relationship between the rotation angle of the balance wheel 31 and the back electromotive voltage.

[0072] Here, we will explain the back electromotive voltage detected by coil 43 as permanent magnet 41 rotates in the forward direction from the rotation angle position of 0°, rotates in the reverse direction due to the elastic force of hairspring 32, and then rotates again in the forward direction due to the elastic force of hairspring 32.

[0073] Moreover, the back electromotive voltage generated in the coil 43 due to the 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 soft magnetic core 42 is defined as a "positive" back electromotive voltage. On the other hand, the back electromotive voltage generated in the coil 43 due to the change in the magnetic field when the N-pole portion 411 moves in a direction away from the first end 421a of the soft magnetic core 42 is defined as a "negative" back electromotive voltage.

[0074] In this embodiment, the permanent magnet 41 is in a magnetically balanced position at a rotation angle of 0°. Therefore, at a rotation angle of 0°, the back electromotive voltage generated in the coil 43 is zero. The permanent magnet 41 is supplied with power from the power spring 11 at a rotation angle of 0°. That is, the angular velocity of the permanent magnet 41 is maximum at the timing immediately after the rotation angle of 0°. Also, while the permanent magnet 41 rotates in the forward direction from a rotation angle of 0° to 180°, the N pole portion 411 moves in a direction approaching the first end 421a. Thus, in this embodiment, the permanent magnet 41 is disposed so that the back electromotive voltages detected in the coil 43 during the forward rotation of 180° from the power supply position are of the same polarity.

[0075] Therefore, while the permanent magnet 41 rotates from a rotation angle of 0° to 180°, the angular velocity of the permanent magnet 41 reaches a maximum, and the positive back electromotive voltage generated in the coil 43 reaches a peak.

[0076] At a rotation angle of 180°, where the permanent magnet 41 is in a magnetically balanced position, the back electromotive voltage generated in the coil 43 becomes zero.

[0077] When the permanent magnet 41 rotates in the positive direction from a rotation angle of 180°, the N pole portion 411 moves in a direction away from the first end portion 421a. Therefore, a negative counter electromotive voltage is generated in the coil 43 while the permanent magnet 41 rotates from a rotation angle of 180° to 340°. The angular velocity of the permanent magnet 41 at this time is smaller than the angular velocity when the permanent magnet 41 moves from a rotation angle of 0° to 180°. Therefore, the absolute value of the peak of the negative counter electromotive voltage is smaller than the absolute value of the peak of the positive counter electromotive voltage.

[0078] The angular velocity of the permanent magnet 41 is at a rotation angle of 340°, which is the turning point of the reciprocating motion. Therefore, the back electromotive voltage generated in coil 43 becomes 0 at a rotation angle of 340°.

[0079] When the permanent magnet 41 reaches a rotation angle of 340°, it starts to rotate in the reverse direction due to the elastic force of the hairspring 32. When the permanent magnet 41 rotates from a rotation angle of 340° to 180°, the N-pole portion 411 moves in a direction approaching the first end 421a. Therefore, a positive counter electromotive voltage is generated in the coil 43 while the permanent magnet 41 rotates from a rotation angle of 340° to 180°.

[0080] Furthermore, at a rotation angle of 180°, where the permanent magnet 41 is in a magnetically balanced position, the back electromotive voltage generated in the coil 43 becomes zero.

[0081] Furthermore, the permanent magnet 41 rotates from the rotation angle 180° to 0°. When the permanent magnet 41 rotates from the rotation angle 180° to 0°, 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 rotation angle 180° to 0°, a negative counter electromotive voltage is generated in the coil 43.

[0082] Furthermore, at a rotation angle of 0°, where the permanent magnet 41 is in a magnetically balanced position, the back electromotive voltage generated in the coil 43 becomes zero.

[0083] When the permanent magnet 41 reaches a rotation angle of 0°, power is supplied from the power spring 11. That is, the angular velocity of the permanent magnet 41 becomes maximum immediately after the rotation angle of 0°. Also, while the permanent magnet 41 rotates from a rotation angle of 0° to -180°, the N-pole portion 411 moves in a direction approaching the first end 421a. Thus, in this embodiment, the permanent magnet 41 is disposed such that the back electromotive voltages detected in the coil 43 during the rotation of the permanent magnet 41 in the reverse direction from the power supply position to -180° have the same polarity.

[0084] Therefore, while the permanent magnet 41 rotates from a rotation angle of 0° to −180°, the angular velocity of the permanent magnet 41 reaches a maximum, and the positive back electromotive voltage generated in the coil 43 reaches a peak.

[0085] At a rotation angle of −180°, where the permanent magnet 41 is in a magnetically balanced position, the back electromotive voltage generated in the coil 43 becomes zero.

[0086] When the permanent magnet 41 rotates in the reverse direction from a rotation angle of -180°, the N pole portion 411 moves in a direction away from the first end portion 421a. Therefore, a negative counter electromotive voltage is generated in the coil 43 while the permanent magnet 41 rotates from a rotation angle of -180° to -340°. The angular velocity of the permanent magnet 41 at this time is lower than the angular velocity when the permanent magnet 41 moves from a rotation angle of 0° to -180°. Therefore, the absolute value of the peak of the negative counter electromotive voltage is smaller than the absolute value of the peak of the positive counter electromotive voltage.

[0087] Furthermore, the angular velocity of the permanent magnet becomes 0 at a rotation angle of −340°, which is the turning point of the reciprocating motion. Therefore, the back electromotive voltage generated in the coil 43 becomes 0 at a rotation angle of −340°.

[0088] When the permanent magnet 41 reaches a rotation angle of -340°, it starts to rotate in the forward direction due to the elastic force of the hairspring 32. When the permanent magnet 41 rotates from a rotation angle of -340° to -180°, the N-pole portion 411 moves in a direction approaching the first end 421a. Therefore, a positive counter electromotive voltage is generated in the coil 43 while the permanent magnet 41 rotates from a rotation angle of -340° to -180°.

[0089] At a rotation angle of −180°, where the permanent magnet 41 is in a magnetically balanced position, the back electromotive voltage generated in the coil 43 becomes zero.

[0090] Furthermore, the permanent magnet 41 rotates from a rotation angle of -180° to 0°. When the permanent magnet 41 rotates from a rotation angle of -180° to 0°, the N pole portion 411 moves in a direction away from the first end portion 421a. Therefore, when the permanent magnet 41 rotates from a rotation angle of -180° to 0°, a negative counter electromotive voltage is generated in the coil 43.

[0091] By repeating the above operation, a back electromotive voltage with a waveform shown in Fig. 9 is generated in the coil 43. As shown in Fig. 9, the peaks of the back electromotive voltage are different between the positive back electromotive voltage and the negative back electromotive voltage. That is, the maximum absolute value of the positive back electromotive voltage is greater than the maximum absolute value of the negative back electromotive voltage. Furthermore, the waveforms of the detected back electromotive voltage are the same when the permanent magnet 41 moves in the positive direction and when it moves in the reverse direction.

[0092] [Control at Start-up of Power Supply Circuit 60] Next, with reference to Figures 10A and 10B, setting control of the start timing of the electromagnetic brake DB when the power supply circuit 60 is started will be described. Figures 10A and 10B are diagrams for explaining an example of setting the start timing of the electromagnetic brake in this embodiment. Note that in this embodiment, the "start timing of the electromagnetic brake DB" refers to the timing at which the electromagnetic brake DB is first applied after the power supply circuit 60 is started. In this embodiment, after the start timing of the electromagnetic brake DB is set, braking control is performed based on the set start timing.

[0093] 10A and 10B, (1) and (2) indicate zero-crossing points detected by the zero-crossing detection circuit. Zero-crossing point (1) is the zero-crossing point when the back electromotive force switches from negative to positive. Zero-crossing point (2) is the zero-crossing point when the back electromotive force switches from positive to negative.

[0094] "DB" in Figures 10A and 10B indicates the period during which the electromagnetic brake is applied. As shown in Figures 10A and 10B, no back electromotive voltage is detected during the period during which the electromagnetic brake DB is applied. "Reference timing" in Figures 10A and 10B is the reference timing for the start timing of the electromagnetic brake DB. "tb2" in Figures 10A and 10B indicates the period from the reference timing to the start timing of the electromagnetic brake. That is, in this embodiment, the electromagnetic brake DB is not applied until the period tb2 has elapsed since the reference timing.

[0095] Rate adjustment is started after a certain amount of power generation is obtained. That is, after the balance wheel 31 in a stopped state starts rotating and the amount of charge stored in the capacitor C shown in Fig. 7 reaches a predetermined value, the power supply circuit 60 starts, and the control circuit 44 starts controlling the brake circuit 80. In Fig. 10A and Fig. 10B, the period from when the balance wheel 31 in a stopped state starts rotating to when the amount of charge reaches a predetermined value is indicated by a thick arrow.

[0096] As described with reference to Fig. 8, during rate adjustment (during braking control), the electromagnetic brake DB is applied in response to the detection timing of the detection signal DE. In this embodiment, the detection timing of the detection signal DE is the timing at which a zero-cross point at which the back electromotive voltage switches from negative to positive is detected.

[0097] Here, in a configuration in which the swing angle (maximum displacement angle) of the balance wheel 31 and the permanent magnet 41 is greater than 180°, the zero-crossing point at which the back electromotive force switches from negative to positive is detected twice as the balance wheel 31 rotates from a rotation angle of 0° to a maximum rotation angle (>180°) and then returns to a rotation angle of 0°. One of these zero-crossing points corresponds to the timing when the rotation angle of the balance wheel 31 is 0°. The other zero-crossing point corresponds to the timing when the rotation angle of the balance wheel 31 is the maximum angle. For this reason, in order to set the start timing of the electromagnetic brake DB based on the zero-crossing point, it is necessary to determine which zero-crossing point corresponds to what rotation angle of the balance wheel 31.

[0098] Therefore, in this embodiment, a configuration is adopted in which the start timing of the electromagnetic brake DB is set based on the detection interval of the zero-crossing points, which are the start and end points of the positive back electromotive voltage. Also, in this embodiment, the zero-crossing point corresponding to the timing when the rotation angle of the balance wheel 31 is 0° is identified, and the application of the electromagnetic brake DB is started with the zero-crossing point as the reference timing.

[0099] Specifically, first, the control circuit 44 acquires the zero crossing point (1) when switching from negative to positive and the next detected zero crossing point (2) when switching from positive to negative, and acquires the detection interval between them, period A. Next, the control circuit 44 acquires the zero crossing point (1) when switching from negative to positive immediately after period A and the next detected zero crossing point (2) when switching from positive to negative, and acquires the detection interval between them, period B.

[0100] Then, the zero-cross point (1) corresponding to the timing when the rotation angle of the balance wheel 31 is 0° is determined based on the length relationship between period A and period B. Then, the start timing of the electromagnetic brake DB is determined based on the zero-cross point (1) according to the determination result.

[0101] As shown in FIG. 6, FIG. 9, FIG. 10A, and FIG. 10B, positive and negative periods alternate in the back electromotive voltage. In addition, when focusing on the positive period of the back electromotive voltage, periods with short cycles alternate with periods with long cycles. The start point of the positive period of the back electromotive voltage and with short cycles corresponds to the timing when the rotation angle of the balance wheel 31 is 0°. The end point of the positive period of the back electromotive voltage and with short cycles corresponds to the timing when the rotation angle of the balance wheel 31 is ±180°. The start point of the positive period of the back electromotive voltage and with long cycles corresponds to the timing when the rotation angle of the balance wheel 31 is the maximum angle (±340°). The end point of the positive period of the back electromotive voltage and with long cycles corresponds to the timing when the rotation angle of the balance wheel 31 is ±180°.

[0102] From the above-mentioned tendency of the waveform of the back electromotive force, the zero cross point corresponding to the timing when the rotation angle of the balance wheel 31 is 0° is the start point of the period in which the back electromotive force is positive and has a short cycle. Therefore, by comparing the periods A and B, it is advisable to set the start point of the period with the shorter cycle as the reference timing.

[0103] 10A, first, the control circuit 44 acquires the zero-cross point (1) at which the power supply circuit 60 switches from negative to positive after the power supply circuit 60 is started. At this point, it is unclear whether the detected zero-cross point (1) is the zero-cross point corresponding to the timing when the rotation angle of the balance wheel 31 is 0° or the zero-cross point corresponding to the timing when the rotation angle of the balance wheel 31 is maximum.

[0104] The control circuit 44 acquires the next detected zero-crossing point (2), which is the zero-crossing point when switching from positive to negative. Then, the control circuit 44 acquires a period A, which is the detection interval between the first detected zero-crossing point (1) and the second detected zero-crossing point (2).

[0105] Furthermore, the control circuit 44 acquires zero crossing point (1) when switching from negative to positive, which is detected after the period A. Furthermore, the control circuit 44 acquires zero crossing point (2) when switching from positive to negative, which is detected next. Then, the control circuit 44 acquires period B, which is the detection interval between the third detected zero crossing point (1) and the fourth detected zero crossing point (2).

[0106] The control circuit 44 compares the period A with the period B, and sets the reference timing based on the comparison result.

[0107] In the example shown in FIG. 10A, period A is shorter than period B. Therefore, the zero cross point (1), which is the start point of period A, corresponds to the timing when the rotation angle of the balance wheel 31 is 0°. Therefore, it is advisable to set the start point of the positive back electromotive voltage that appears next after period B, which has a long cycle, as the reference timing. In the example shown in FIG. 10A, the next zero cross point (1) detected after period B has elapsed is set as the reference timing. That is, the fifth zero cross point (1) detected after the start of zero cross point detection is set as the reference timing. Then, in the example shown in FIG. 10A, the operation of the electromagnetic brake DB begins after a period tb2 has elapsed since the fifth zero cross point (1) was detected.

[0108] In the example shown in FIG. 10B, the period B is shorter than the period A. Therefore, the zero cross point (1), which is the start point of the period B, corresponds to the timing when the rotation angle of the balance wheel 31 is 0°. Therefore, it is advisable to set the start point of the positive back electromotive voltage that appears after the period B as the reference timing. In the example shown in FIG. 10B, the zero cross point (1) detected for the third time after the period B has elapsed is set as the reference timing. In other words, the zero cross point (1) detected for the seventh time after the start of zero cross point detection is set as the reference timing. Then, in the example shown in FIG. 10B, the operation of the electromagnetic brake DB is started after the period tb2 has elapsed since the seventh zero cross point (1) was detected.

[0109] FIG. 11 is a flowchart showing an example of setting control of the start timing of the electromagnetic brake in this embodiment.

[0110] After the power supply circuit 60 is started up by power generation caused by the motion of the permanent magnet 41 (Y in ST101), setting control of the start timing of the electromagnetic brake is performed.

[0111] First, the control circuit 44 acquires the zero-crossing points detected by the zero-crossing detection circuit after the power supply circuit 60 is started. The first zero-crossing point acquired is the zero-crossing point (1) detected when the back electromotive force switches from negative to positive. After acquiring the first detected zero-crossing point (1) (ST0102), the control circuit 44 successively acquires the second to fourth detected zero-crossing points (ST103 to ST105).

[0112] The control circuit 44 acquires period A, which is the detection interval between the first detected zero cross point (1) and the second detected zero cross point (2), and period B, which is the detection interval between the third detected zero cross point (1) and the fourth detected zero cross point (2), and determines whether period A and period B are long or short (ST106).

[0113] If period A is shorter than period B (Y in ST106), the zero-cross point corresponding to the first detected zero-cross point (1) is used as the reference for the start timing of the electromagnetic brake DB. In other words, the zero-cross point (1) detected for the fifth time after control for setting the start timing of the electromagnetic brake DB is started is used as the reference timing (ST107). Then, after waiting for the passage of period tb2 after obtaining the fifth detected zero-cross point (1) (Y in ST108), the electromagnetic brake is started to act (ST109).

[0114] If period B is shorter than period A (N in ST106), the zero-cross point corresponding to the third detected zero-cross point (1) is set as the reference for the start timing of the electromagnetic brake DB. That is, the zero-cross point (1) detected seventh time after the control for setting the start timing of the electromagnetic brake DB is started is set as the reference timing (ST110 to ST112). Then, after waiting for the passage of period tb2 from obtaining the seventh detected zero-cross point (1) (Y in SY108), the application of the electromagnetic brake is started (ST109).

[0115] [Setting the timing for starting the electromagnetic brake during braking control] Next, a control when the deviation amount t of the detection timing of the detection signal DE from the output timing of the reference signal OS becomes larger than a predetermined value during braking control will be described with reference to Fig. 12. Fig. 12 is a flowchart showing an example of braking control in this embodiment.

[0116] In the mechanical timepiece 1, the detection timing of the detection signal DE may deviate significantly from the output timing of the reference signal OS due to the influence of a strong external shock or an external magnetic field. As described with reference to FIG. 8, in the braking control, the electromagnetic brake DB is applied according to the detection timing of the detection signal DE. Therefore, if the detection timing of the detection signal DE deviates, the electromagnetic brake DB cannot be applied at the appropriate timing. For example, if the detection timing of the detection signal DE deviates significantly, the zero crossing point (1) when switching from negative to positive, which corresponds to the timing when the rotation angle of the balance wheel 31 is ±180°, may be erroneously set as the reference timing. That is, the zero crossing point (1) which is the start point of the period B shown in FIG. 10A or the zero crossing point (1) which is the start point of the period A shown in FIG. 10B may be set as the reference timing. As a result, the accuracy of the rate is reduced.

[0117] Therefore, in this embodiment, when the detection timing of the detection signal DE significantly deviates from the output timing of the reference signal OS, a configuration is adopted in which the rate accuracy is maintained by performing the processes ST102 to ST112 shown in Fig. 11. That is, when the detection timing of the detection signal DE significantly deviates during braking control, the setting control of the start timing of the electromagnetic brake is performed in the same manner as when the power supply circuit 60 is started up.

[0118] The control circuit 44 acquires the detection signal DE detected by the zero-cross detection circuit 45 (Y in ST201), and calculates the amount of deviation t, which is the time difference between the detection timing of the detection signal DE and the output timing of the reference signal OS (ST202). If the amount of deviation t is within the period t_th (Y in ST203), the control circuit 44 waits a predetermined period after detecting the detection signal DE and then applies the electromagnetic brake DB (ST204). In other words, the braking control continues.

[0119] On the other hand, if the deviation t is outside the period t_th (N in ST203), the process executes ST102 to ST112 shown in Fig. 11 (ST205). That is, the start timing of the electromagnetic brake DB is set based on the detection interval of the zero-crossing point. After the start timing of the electromagnetic brake DB is newly set, the process returns to ST201 in Fig. 12 to resume braking control.

[0120] For example, the period t_th may be a period from T-(t_th) / 2 to T+(t_th) / 2, where T is the output timing of the reference signal OS. That is, when the detection timing of the detection signal DE is earlier than the output timing of the reference signal OS by (t_th) / 2 or more, or when it is later than the output timing of the reference signal OS by (t_th) / 2 or more, the processes of ST102 to ST112 shown in FIG. 11 may be executed during the execution of the braking control.

[0121] By performing the process of setting the timing for starting the electromagnetic brake during braking control in this manner, normal braking control can be restored even if the vehicle is affected by a strong external impact, an external magnetic field, or the like.

[0122] [First Modification] Next, a first modified example of this embodiment will be described with reference to Fig. 13 and Fig. 14. Fig. 13 is a diagram for explaining detection of a zero cross point according to the magnitude of the oscillation angle of the balance wheel. Fig. 14 is a flowchart showing setting control of the start timing of the electromagnetic brake in the first modified example of this embodiment. Note that in Fig. 14, the processes other than those surrounded by the wavy line are the same as the processes described in Fig. 11, so the same reference numerals are used and detailed description is omitted.

[0123] When the power supplied from the power spring 11 is small, the oscillation angle of the balance wheel 31 becomes small. When the oscillation angle of the balance wheel 31 is small, the amount of power generated becomes small. Therefore, even if braking control is started after the power supply circuit 60 is started, if the oscillation angle of the balance wheel 31 is small, the amount of power generated is not sufficient and the power supply circuit 60 may stop.

[0124] The solid line in the graph of Fig. 13 indicates the relationship between the rotation angle and the back electromotive force when the oscillation angle of the balance wheel 31 is 180° or less. The dotted line in the graph of Fig. 13 indicates the relationship between the rotation angle and the back electromotive force when the oscillation angle of the balance wheel 31 is greater than 180°.

[0125] As shown in Fig. 13, when the swing angle of the balance wheel 31 is greater than 180°, five zero crossing points are detected during the time from when the balance wheel rotates from a rotation angle of 0° to the maximum angle until it returns to a rotation angle of 0° again. This is as described above with reference to Figs. 10A and 10B.

[0126] On the other hand, as shown in FIG. 13, when the oscillation angle of the balance wheel 31 is 180° or less, three zero crossing points are detected during the time when the balance wheel 31 rotates from a rotation angle of 0° to the maximum angle and returns to the rotation angle of 0°. The zero crossing point (1)' shown in FIG. 13 corresponds to the state where the rotation angle of the balance wheel 31 is 0°. The zero crossing point (2)' shown in FIG. 13 corresponds to the state where the rotation angle of the balance wheel 31 is at the maximum angle (<180°). In other words, when the oscillation angle of the balance wheel 31 is 180° or less, there is no zero crossing point detected at the rotation angle of the balance wheel 31 between 0° and the maximum angle. This is because the rotation angles of the permanent magnet 41 where the back electromotive voltage becomes zero are only the rotation angle of 0°, which is the position of magnetic balance, and the maximum angle, which is the turning back point of the rotation. For this reason, when the oscillation angle of the balance wheel 31 is 180° or less, the process described with reference to FIG. 11 cannot be applied.

[0127] Therefore, in the first modified example, the timing to start the electromagnetic brake DB is set after the oscillation angle of the balance wheel 31 becomes sufficiently large. Specifically, the timing to start the electromagnetic brake is controlled and set after the detection interval between the first detected zero-cross point and the fourth detected zero-cross point falls below a certain value.

[0128] In the first modified example, as shown in Fig. 14, after ST105, it is determined whether the detection interval of the zero crossing points is equal to or less than a certain value (ST113). Specifically, if the detection interval between the first detected zero crossing point and the fourth detected zero crossing point is greater than a certain value (N in ST113), the process does not proceed to the process for setting the start timing of the electromagnetic brake. This is because if the detection interval of the zero crossing points is greater than a certain value, the torque of the power spring is insufficient and the oscillation angle of the balance wheel 31 may be less than 180°.

[0129] On the other hand, if the detection interval between the first detected zero crossing point and the fourth detected zero crossing point is equal to or less than a certain value (Y in ST113), the processes of ST106 to ST112 are performed as in Fig. 11. Note that if in ST113 the value does not fall below the certain value a certain number of times in succession, even if it does fall below the certain value thereafter, it is possible not to immediately proceed to the processes after ST106. Then, if the value falls below the certain value a certain number of times in succession thereafter, it is possible to proceed to the processes after ST106. Note that the certain number of times may be any number.

[0130] In ST113, the detection interval of the zero crossing points to be determined may be any interval. For example, it may be the detection interval between the first detected zero crossing point and the second detected zero crossing point, or the detection interval between the second detected zero crossing point and the fourth detected zero crossing point. The fixed value may be set appropriately depending on which detection interval is used for the determination.

[0131] Furthermore, the determination of whether the oscillation angle of the balance wheel 31 is sufficient may be made based on the magnitude of the back electromotive voltage. For example, if the peak of the back electromotive voltage is equal to or greater than a predetermined threshold, it is preferable to determine that the oscillation angle of the balance wheel 31 is sufficient, and to perform the processes ST106 to ST112 in Fig. 14. On the other hand, if the peak of the back electromotive voltage is less than the predetermined threshold, it is preferable not to proceed to the process for setting the start timing of the electromagnetic brake.

[0132] In the first modified example, braking control can be started in a state where the amount of power generation can be maintained. Therefore, it is possible to prevent the power supply circuit 60 from stopping after braking control has started. Also, in the first modified example, as in the present embodiment, the start timing of the electromagnetic brake DB can be appropriately set. As a result, the rate accuracy can be maintained. Also, when a user confirms that the rate accuracy is not improved by not transitioning to braking control, it is possible to urge the user to wind the crown.

[0133] [Second modified example] Next, a second modified example of this embodiment will be described with reference to Fig. 15 and Fig. 16. Fig. 15 is a diagram for explaining an example of setting the start timing of the electromagnetic brake in the second modified example of this embodiment. Fig. 15 is a diagram corresponding to Fig. 10A and Fig. 10B referred to in the description of this embodiment. Fig. 16 is a flowchart showing an example of setting control of the start timing of the electromagnetic brake in the second modified example of this embodiment.

[0134] In the case of the mechanical timepiece 1, when it is subjected to a strong external shock or an external magnetic field, noise occurs in the back electromotive force, and the zero cross point may be detected at a timing that would not be detected when the balance wheel 31 is rotating normally. Figure 15 shows zero cross points E1 and E2 that are detected due to noise. When noise occurs in this way, the start timing of the electromagnetic brake DB cannot be set appropriately.

[0135] Therefore, in the second modified example, periods A and B are obtained multiple times, and it is determined whether the length relationship between periods A and B is the same, and if the length relationships are the same, the start point of the period A or B which has the shorter cycle is set as the reference timing. By adopting such a configuration, it is possible to appropriately set the start timing of the electromagnetic brake DB even when noise occurs.

[0136] In the example shown in FIG. 15, the control circuit 44 acquires a period A1 which is the detection interval between the first detected zero crossing point (1) and the second detected zero crossing point (2), and a period B1 which is the detection interval between the third detected zero crossing point (1) and the fourth detected zero crossing point (2).

[0137] Thereafter, the control circuit 44 further acquires a period A2 which is the detection interval between the fifth detected zero crossing point (1) and the sixth detected zero crossing point (2), and a period B2 which is the detection interval between the seventh detected zero crossing point (1) and the eighth detected zero crossing point (2).

[0138] In the example shown in Fig. 15, between periods A1 and B1, period B1 is shorter. Meanwhile, between periods A2 and B2, period A2 is shorter. Therefore, it is impossible to determine which of the start points of periods A1 and A2 and the start points of periods B1 and B2 is the zero cross point corresponding to the timing when the rotation angle of the balance wheel 31 is 0°. The reason why it is impossible to determine which of the start points of periods A1 and A2 and the start points of periods B1 and B2 is the zero cross point corresponding to the timing when the rotation angle of the balance wheel 31 is 0° is because the zero cross points detected the third and fourth times are caused by noise.

[0139] Therefore, in the example shown in FIG. 15, the control circuit 44 further acquires a period A3 which is the detection interval between the 9th detected zero crossing point (1) and the 10th detected zero crossing point (2), and a period B3 which is the detection interval between the 11th detected zero crossing point (1) and the 12th detected zero crossing point (2).

[0140] 15, period A3 is shorter than period B3. This relationship is the same as that between periods A2 and B2. Therefore, it can be determined that the starting points of periods A2 and A3 are zero-crossing points corresponding to the timing when the rotation angle of the balance wheel 31 is 0°.

[0141] 16, in the second modification, after performing the processes of ST102 to ST105, it is determined whether or not the zero cross point (1) and the zero cross point (2) have each been detected four or more times (ST301). This is because in the second modification, it is necessary to acquire period A at least twice and period B at least twice.

[0142] If it is determined that the zero crossing point (1) and the zero crossing point (2) have not been detected four or more times each (N in ST301), the process returns to ST102 and continues detecting the zero crossing point.

[0143] If it is determined that zero cross point (1) and zero cross point (2) have each been detected four or more times (Y in ST301), it is determined whether the length relationship between the earlier period A and period B is the same as the length relationship between the later period A and period B (ST302). If it is determined that they are not the same (N in ST302), the process returns to ST102 to continue detecting zero cross points. If it is determined that they are the same (Y in ST302), the process proceeds to ST106 and subsequent processes.

[0144] 16, an example is shown in which the process proceeds to ST106 and subsequent steps when the magnitude relationship between period A and period B is the same two consecutive times, but this is not limited to this. For example, the process may proceed to ST106 and subsequent steps when the magnitude relationship between period A and period B is the same three or more consecutive times.

[0145] [Third Modification] Next, a third modified example of this embodiment will be described with reference to Fig. 17. Fig. 17 is a diagram for explaining an example of setting the start timing of the electromagnetic brake in the third modified example of this embodiment. Fig. 17 is a diagram corresponding to Fig. 10A and Fig. 10B referred to in the description of this embodiment.

[0146] If the electromagnetic brake DB is started to operate when the frequency of the balance wheel 31 is high after the power supply circuit 60 is started, the brake will be applied suddenly, and there is a possibility that the frequency cannot be reduced to the desired frequency. Therefore, in the third modified example, the weak electromagnetic brake DB1, which has a weaker braking force than the electromagnetic brake DB during rate adjustment, is applied before the timing when the electromagnetic brake DB starts to operate, thereby reducing the frequency of the balance wheel 31 and detecting the zero-cross point. The weak electromagnetic brake DB1 corresponds to the braking force when the electromagnetic brake DB is intermittently operated.

[0147] By adopting such a configuration, it is possible to reduce the difference in the frequency of the balance wheel 31 before and after the start timing of the electromagnetic brake DB. This makes it easier to obtain the desired frequency. As a result, the accuracy of the rate can be maintained. Note that it is sufficient for the weak electromagnetic brake DB1 to have a braking force at least smaller than that of the electromagnetic brake DB. The interval between the pulses that constitute the weak electromagnetic brake DB is arbitrary, and it does not have to be constantly inactive while the zero crossing point is being detected.

[0148] The control of the third modified example is not limited to this embodiment, and may be applied to the first and second modified examples of this embodiment.

[0149] [others] In the present embodiment and its modified example, the start timing of the electromagnetic brake DB is set based on the detection interval of the zero crossing points, but this is not limiting. The start timing of the electromagnetic brake DB may be set based on the period of the back electromotive voltage. Furthermore, the start timing of the electromagnetic brake DB is not limited to being based on the period, and may be set based on, for example, the magnitude of the back electromotive voltage. As shown in Figs. 10A and 10B, the peak of the back electromotive voltage is larger in the shorter period of period A or period B. Therefore, the start timing of the application of the electromagnetic brake DB may be set based on the zero crossing point, which is the start point of the period with the higher peak of the back electromotive voltage, as the reference timing. In this case, it is preferable to configure a circuit capable of detecting the difference in the back electromotive voltage peaks.

[0150] In the present embodiment and its modified example, the example of acquiring the period of the positive back electromotive voltage has been described, but the present invention is not limited to this, and the period of the negative back electromotive voltage may be acquired. In this case, the zero cross point at which the voltage switches from positive to negative may be set as the zero cross point (1) detected for the first time.

[0151] Furthermore, in the above embodiment and modified example, an example has been described in which the braking force is applied by the electromagnetic brake DB, but the present invention is not limited to this, and the braking force may be applied by a speed control pulse output from the speed control pulse output circuit 46. That is, the speed control pulse output circuit 46 may output a speed control pulse to brake the movement of the permanent magnet 41, thereby controlling the movement of the balance wheel 31 and adjusting the rate. Note that the rate adjustment (braking control) using the speed control pulse may include control of energizing the coil 43 so that a torque acts in a direction that speeds up the movement of the permanent magnet 41.

[0152] Furthermore, the rate adjustment means 40 obtains a detection signal based on the operation of the two-pole magnetized permanent magnet 41, and if there are any members around the permanent magnet 41 that have a magnetic effect, the detection accuracy may decrease. For this reason, it is preferable to use materials that have little magnetic effect as the materials for the members around the permanent magnet 41. For example, a resin material is preferable for the material of the support member 33 and the hairpin holder 34. Also, phosphorus bronze or brass is preferable for the material of the fastener 33a for fixing the support member 33 to the main plate 10. Also, a resin material, aluminum, or brass is preferable for the material of the balance wheel 31.

[0153] Also, as described above, by making the hairspring 32 from resin in order to reduce the Young's modulus, the magnetic effect on the permanent magnet 41 can be reduced compared to when it is made of metal. Also, if the hairspring 32 is made of a magnetic metal, it may be magnetically affected by the permanent magnet 41, causing the shape and attitude of the hairspring 32 to change. In this embodiment, by making the hairspring 32 from resin, the shape and attitude of the hairspring 32 itself can be stabilized. Also, a separate magnetic shield made of a magnetic material may be provided in the mechanical timepiece 1. This prevents the forward and reverse rotational motion of the permanent magnet 41 (balance wheel 31) from being disturbed even when an external magnet approaches the mechanical timepiece 1, and allows stable braking control. [Explanation of symbols]

[0154] 1 mechanical watch, 2 winding stem, 10 main plate, 10a positioning pin, 10b aperture, 11 power spring, 12 wheel train, 122 second wheel, 123 third wheel, 124 fourth wheel, 13 pointer, 131 second hand, 20 escapement mechanism, 21 escape wheel, 22 anchor, 221 Anchor shaft, 222 rod portion, 223 first arm portion, 224 second arm portion, 30 speed regulating mechanism, 31 balance wheel, 311 balance shaft, 32 balance spring, 33 support member, 33a pipe, 33b screw, 34 balance holder, 35 frame member, 40 rate adjusting means, 41 permanent magnet, 42 soft magnetic core, 421 first magnetic portion, 421a first end portion, 422 second magnetic portion, 422a second end portion, 43 coil, 44 control circuit, 45 zero cross detection circuit, 46 speed regulating pulse output circuit, 47 frequency divider circuit, 48 oscillation circuit, 50 rectifier circuit, 60 power supply circuit, 70 quartz crystal oscillator, 80 braking circuit, n11, n12, n21, n22 notches.

Claims

1. A power source, a balance wheel driven by the power from the power source, and a hairspring that elastically deforms to cause the balance wheel to rotate forward and backward, and a speed control mechanism including the same, a two-polarized permanent magnet that rotates forward and backward in accordance with the forward and backward rotational movement of the balance wheel, a coil, a step adjustment means for adjusting the step by performing a braking control that generates a braking force for braking the permanent magnet, including, the maximum displacement angle in the forward and backward rotational movement of the permanent magnet is greater than 180°, the step adjustment means sets the timing for generating the braking force based on the detection voltage generated in the coil due to the forward and backward rotational movement of the permanent magnet, and performs the braking control based on the set timing, a mechanical clock.

2. The step adjustment means controls so as not to perform the braking control when the detection voltage does not satisfy a predetermined condition, The mechanical clock according to Claim 1.

3. The step adjustment means sets the timing for generating the braking force based on the period of the detection voltage, The mechanical clock according to Claim 1.

4. The step adjustment means acquires a first period that is either positive or negative of the detection voltage and a second period that is either one of them and appears next to the first period, and sets the timing for generating the braking force based on the length relationship between the first period and the second period, The mechanical clock according to Claim 1.

5. including a zero-cross detection circuit that detects a zero-cross point at which the detection voltage switches between positive and negative, The step adjustment means sets the timing for generating the braking force based on the detection intervals of a plurality of zero-cross points detected by the zero-cross detection circuit, The mechanical clock according to Claim 1.

6. The step adjustment means, a first period that is the detection interval between a first zero-cross point detected when the detection voltage switches from negative to positive and a zero-cross point detected immediately after that and at which the detection voltage switches from positive to negative, a second period that is the detection interval between a third zero-cross point detected immediately after the second zero-cross point and at which the detection voltage switches from negative to positive and a fourth zero-cross point detected immediately after that and at which the detection voltage switches from positive to negative, acquires, Based on the length relationship between the first period and the second period, set the timing for generating the braking force. The mechanical watch according to claim 5.

7. The pace adjustment means sets the starting point of the period corresponding to the shorter one of the first period and the second period as the reference timing of the timing for generating the braking force. The mechanical watch according to claim 4 or 6.

8. Including a zero-cross detection circuit for detecting a zero-cross point at which the detected voltage switches between positive and negative, The pace adjustment means, When the deviation amount between the detection timing of the zero-cross point and the output timing of the reference signal output from the reference signal source during the braking control is equal to or greater than a predetermined value, set the timing for generating the braking force, and resume the braking control based on the set timing. The mechanical watch according to claim 1.

9. Including a zero-cross detection circuit for detecting a zero-cross point at which the detected voltage switches between positive and negative, The pace adjustment means sets the timing for generating the braking force after the detection interval of the zero-cross point becomes equal to or less than a certain value after the ten-wheel in the stopped state starts the forward and reverse rotational movements. The mechanical watch according to claim 1.

10. The pace adjustment means acquires the length relationship between the first period and the second period at least two or more times, and if the current length relationship is different from the previous length relationship, continues to acquire the length relationship. The mechanical watch according to claim 4 or 6.

11. The pace adjustment means generates a weak braking force weaker than the braking force in the period before setting the timing for generating the braking force. The mechanical watch according to claim 1.

12. The pace adjustment means includes a braking circuit that generates an electromagnetic brake for braking the permanent magnet by short-circuiting the coil. The mechanical watch according to claim 1.

13. Including a first end portion provided along the outer periphery of the permanent magnet and a second end portion provided along the outer periphery of the permanent magnet and arranged to face the first end portion through the permanent magnet, and having a soft magnetic core that forms a magnetic circuit together with the coil. The permanent magnet is arranged such that the magnetization direction faces the side of the first end portion or the second end portion in a state where the hairspring is at the neutral position of its elastic deformation. The mechanical watch according to claim 1.

14. The ten-wheel is in a power supply position where power from the power source is supplied in a state where the beard hairspring is in the neutral position. The permanent magnet is arranged such that the detected voltage detected until it rotates 180° in the positive or negative direction from the power supply position has the same polarity. The mechanical timepiece according to claim 13.

15. A power source, A speed regulating mechanism including a ten-wheel driven by the power from the power source, and a beard hairspring that elastically deforms to rotate the ten-wheel forward and backward. A two-polarized permanent magnet that rotates forward and backward along with the forward and backward rotational movement of the ten-wheel, A coil, A pace adjustment means for adjusting the pace by performing braking control to generate a braking force for braking the permanent magnet. Including, When the detected voltage generated in the coil by the forward and backward rotational movement of the permanent magnet does not satisfy a predetermined condition, the pace adjustment means controls not to perform the braking control. Mechanical timepiece.

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