Mechanical watch

Abstract

To provide a highly durable mechanical watch 1 while maintaining accuracy in timekeeping. [Solution] The mechanical clock 1 includes a speed control mechanism 30 which includes a power mainspring 11, a balance wheel 31 driven by the power from the power mainspring 11, and a hairspring 32 which is elastically deformed to cause the balance wheel 31 to rotate in forward and reverse directions; a bipolarized permanent magnet 40 which rotates in forward and reverse directions in accordance with the forward and reverse rotation of the balance wheel 31; a coil 43 and a rotation detection circuit 45 which detects a detection signal based on a detection voltage generated in the coil 43 due to the movement of the permanent magnet 40 accompanying the forward and reverse movement of the balance wheel 31; a braking circuit 80 which applies a braking force to brake the permanent magnet 40 by short-circuiting the terminals of the coil 43; and a control circuit 44 which controls the duration of the braking force based on at least the detection voltage and a reference signal from a reference signal source.

Description

Technical Field

[0004] ,

[0006] , , , , , , , , , , , , , , , , , ,

[0005]

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

Background Art

[0002] In conventional mechanical watches, 1 second is created based on the reciprocating motion of the balance spring. As the number of reciprocating motions per second increases, the error per second, that is, the influence on the rate accuracy, becomes smaller. For example, Patent Document 1 discloses a technique for reducing the inertia of the escapement mechanism to vibrate the balance spring at high speed and improving the rate accuracy. Further, Patent Documents 2 and 3 disclose techniques for adjusting the rate in a mechanical watch provided with a balance spring.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, the faster the balance spring moves, the more easily each mechanism for transmitting power wears out, and the durability decreases. On the other hand, if the movement of the balance spring is made slow, it becomes difficult to ensure the rate accuracy.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a mechanical watch that maintains the rate accuracy and has high durability.

Means for Solving the Problems

[0006] (1) A mechanical clock having a power source, a balance wheel driven by power from the power source, a hairspring that elastically deforms to cause the balance wheel to rotate in forward and reverse directions, a bipolar permanent magnet that rotates in forward and reverse directions in conjunction with the forward and reverse rotation of the balance wheel, a coil, a rotation detection circuit that detects a detection signal based on a detection voltage generated in the coil by the movement of the permanent magnet accompanying the forward and reverse movement of the balance wheel, a braking circuit that applies a braking force to brake the permanent magnet by short-circuiting the terminals of the coil, and a control circuit that controls the duration of the braking force based on at least the detection voltage and a reference signal from a reference signal source.

[0007] (2)(1) A mechanical clock in which the operating period includes a period after the rotational speed of the balance wheel in one direction of rotation reaches its maximum value, and then the timing when the rotational speed of the balance wheel in the opposite direction of rotation reaches its maximum value.

[0008] (3) A mechanical clock in which, in (1) or (2), the reference signal is output at a first interval and the operating period is shorter than the first interval, and the reference signal is output at a second interval longer than the first interval and the operating period is shorter than the second interval, wherein the control circuit switches between the first braking mode and the second braking mode.

[0009] (4)(3) A mechanical clock in which the braking circuit is configured to generate a plurality of braking forces having different durations in the first braking mode, and to generate a plurality of braking forces having different durations in the second braking mode.

[0010] (5)(4) A mechanical clock in which the duration of action in the second braking mode includes a period longer than the first interval.

[0011] (6)(5) A mechanical clock in which the braking circuit generates the braking force for the operating period corresponding to the amount of deviation between the output timing of the reference signal and the detection timing of the detection signal.

[0012] (7)(5) or (6), the braking circuit generates a braking force for a second operating period that is longer than the first operating period generated when the detection timing at which the detection signal is detected is within a predetermined range relative to the output timing of the reference signal, if the detection timing at which the detection signal is detected is ahead of the output timing of the reference signal.

[0013] (8)(7) A mechanical clock in which the braking circuit generates a braking force for a third operating period shorter than the first operating period generated when the detection timing at which the detection signal is detected is within a predetermined range with respect to the output timing of the reference signal, or does not generate the braking force.

[0014] A mechanical clock in which, in any of (9), (5), to (8), the control circuit switches between the first braking mode and the second braking mode based on the amount of deviation between the output timing of the reference signal and the detection timing of the detection signal.

[0015] A mechanical clock having a temperature sensor in any of (10), (5), to (9), wherein the control circuit switches between the first braking mode and the second braking mode based on the output of the temperature sensor.

[0016] (11) A mechanical clock in any of (1) to (10) that includes a non-detection period in which the detection signal is not detected regardless of the magnitude of the detection voltage.

[0017] (12)(11) A mechanical clock in which the non-detection period is longer than the operating period.

[0018] (13) In (11) or (12), the braking circuit is configured to be able to generate a plurality of braking forces with different acting periods, and the non-detection period is longer than at least any one of the acting periods of the plurality of braking forces, mechanical timepiece.

[0019] (14) In any one of (11) to (13), the non-detection period is a period after the rotational speed of the ten-wheel reaches the maximum value in the forward and reverse rotational movements of the ten-wheel and before the rotational speed of the ten-wheel reaches the maximum value next, mechanical timepiece.

[0020] (15) In any one of (1) to (14), the control circuit controls the acting period so as to reciprocate the ten-wheel once in 2 seconds, mechanical timepiece.

[0021] (16) In any one of (1) to (15), the control circuit generates the braking force by the braking circuit every time the detection signal is detected, mechanical timepiece.

[0022] (17) In any one of (1) to (16), the braking circuit is configured to be able to generate a plurality of braking forces with different acting periods, and the control circuit controls the acting period by controlling at least one of the start point or the end point timing of the acting period, mechanical timepiece.

[0023] (18) In (17), in a plurality of acting periods included in the first acting period group, the control circuit fixes the timing of the start point and controls the timing of the end point, and in a plurality of acting periods included in the second acting period group, the control circuit controls the timing of the start point and fixes the timing of the end point, and each of the plurality of acting periods included in the second acting period group is longer than the plurality of acting periods included in the first acting period group, mechanical timepiece.

[0024] (19)(18), the braking circuit is configured to be able to generate a plurality of braking forces with different action periods within a preset braking interval. The timings of the start points of the plurality of action periods included in the first action period group are a predetermined reference timing after the start point of the braking interval, and the timings of the end points of the plurality of action periods included in the first action period group are timings before the end point of the braking interval. The timings of the start points of the plurality of action periods included in the second action period group are timings earlier than the reference timing, and the timings of the end points of the plurality of action periods included in the second action period group are the timings of the end point of the braking interval. A mechanical clock.

[0025] (20)(19), the reference timing is a timing after the rotation speed of the ten-wheel reaches the maximum value in the forward and reverse rotational motions of the ten-wheel and before the peak of the waveform of the detection voltage occurs next. A mechanical clock.

[0026] (21) In any one of (1) to (20), the control circuit controls the action period based on the deviation amount between the detection timing of the detection signal and the output timing of the reference signal. When the number of times that the braking force with the same action period acts continuously is equal to or more than a predetermined number of times and the deviation amount is equal to or more than a predetermined amount, the action period is changed. A mechanical clock.

[0027] (22) A mechanical clock having a speed regulating mechanism including a power source, a ten-wheel driven by the power from the power source, and a hairspring that elastically deforms to rotate the ten-wheel forward and backward, a two-polarized permanent magnet that rotates forward and backward with the forward and backward rotational motions of the ten-wheel, a coil, a speed regulating pulse output circuit that outputs a speed regulating pulse for controlling the motion of the ten-wheel based on the detection voltage generated in the coil due to the motion of the permanent magnet accompanying the forward and backward motions of the ten-wheel and the reference signal of a reference signal source, a rotation detection circuit that detects a detection signal based on the detection voltage, and a control circuit that controls the braking force for braking the permanent magnet every time the detection signal is detected.

Advantages of the Invention

[0028] According to aspects (1) to (22) of the present invention described above, it is possible to provide a mechanical watch that maintains accuracy and has high durability. [Brief explanation of the drawing]

[0029] [Figure 1] This is a perspective view showing the base plate and the components incorporated therein according to the first embodiment. [Figure 2] This is a perspective view showing the power transmission mechanism and its surroundings in the first embodiment. [Figure 3] This is an exploded perspective view showing the speed control mechanism and its surrounding components in the first embodiment, separated from the base plate. [Figure 4] This is a plan view showing the soft magnetic core and its surroundings according to the first embodiment, and an enlarged plan view showing a part thereof in an enlarged view. [Figure 5] This is a block diagram showing the overall configuration of a mechanical clock according to the first embodiment. [Figure 6] This diagram illustrates the relationship between the operation of the tenon ring in the first embodiment and the back electromotive force generated in the coil. [Figure 7A] This figure illustrates the control of the movement of a permanent magnet by a speed control pulse in the first embodiment. [Figure 7B] This figure illustrates the control of the movement of a permanent magnet by a speed control pulse in the first embodiment. [Figure 8] This is a timing chart showing an example of braking control in the first embodiment of the first embodiment. [Figure 9] This is a circuit diagram of the first embodiment. [Figure 10] This is a timing chart showing an example of braking control in the second embodiment of the first embodiment. [Figure 11] This is a timing chart showing an example of braking control in the third embodiment of the first embodiment. [Figure 12] This diagram illustrates the timing of the electromagnetic brake's action in the first embodiment. [Figure 13] This is a timing chart showing an example of braking control in the fourth embodiment of the first embodiment. [Figure 14] This is a timing chart showing an example of braking control in the fifth embodiment of the first embodiment. [Figure 15] This is a timing chart showing an example of braking control in the sixth embodiment of the first embodiment. [Figure 16] This is a flowchart showing an example of braking control according to the first embodiment. [Figure 17] This is a timing chart showing an example of braking control in a modified version of the first embodiment. [Figure 18] This is a timing chart showing an example of braking control in a modified version of the first embodiment. [Figure 19] This is a timing chart showing an example of braking control in a modified version of the first embodiment. [Figure 20] This flowchart shows an example of braking control in a modified version of the first embodiment. [Figure 21] This timing chart shows an example of braking control when a power supply circuit starts up from a stopped state. [Figure 22] This is a timing chart showing an example of the output timing of a reference signal. [Figure 23] This graph shows the relationship between the rotation angle of the balance wheel and the holding torque acting on the permanent magnet, as well as the relationship between the rotation angle of the balance wheel and the torque of the hairspring. [Figure 24] This diagram illustrates the direction in which the torque and holding torque of the hairspring act. [Figure 25] This timing chart shows an example of braking control when the torque of the power spring weakens. [Figure 26] This figure shows an example of a detection signal when it is determined that the torque of the power spring has weakened. [Figure 27] This timing chart shows an example of braking control when the torque of the power spring weakens. [Figure 28]This timing chart shows an example of braking control that improves the accuracy of rotation detection. [Figure 29] Figure 28 is a circuit diagram for implementing the braking control shown. [Figure 30] This is a timing chart showing an example of braking control in another modification of the first embodiment. [Figure 31] This is a timing chart showing an example of braking control in another modification of the first embodiment. [Figure 32] This flowchart shows an example of braking control in another modification of the first embodiment. [Figure 33] This figure shows an example of braking control in the second embodiment. [Figure 34] This figure shows an example of braking control in the second embodiment. [Figure 35] This is a flowchart showing an example of braking control in the second embodiment. [Figure 36] This figure illustrates an example of braking control in the third embodiment. [Figure 37A] This figure shows an example of varying the duration of the electromagnetic brake's operation by fixing either the start or end point. [Figure 37B] This figure shows an example of varying the duration of operation of an electromagnetic brake based on a predetermined reference timing. [Figure 37C] This figure shows an example of varying the duration of the electromagnetic brake's operation depending on the rank. [Figure 38] This flowchart shows an example of rank switching. [Figure 39] Figure 38 is a flowchart showing a modified example of rank switching. [Modes for carrying out the invention]

[0030] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.

[0031] [Overall Structure Overview] First, an overview of the overall configuration of the mechanical clock 1 according to the first embodiment will be described with reference to Figures 1 to 5. Figure 1 is a perspective view showing the base plate and each component incorporated therein in the first embodiment. Figure 2 is a perspective view showing the power transmission mechanism and its surroundings in the first embodiment. Figure 3 is an exploded perspective view showing the speed control mechanism and its surrounding components separated from the base plate in the first embodiment. Figure 4 is a plan view showing the soft magnetic core and its surroundings in the first embodiment, and an enlarged plan view showing a part thereof in an enlarged view. Figure 5 is a block diagram showing the overall configuration of the mechanical clock according to the first embodiment. Figures 1 to 3 show the view from the back of the mechanical clock 1. The back side is the side in the thickness direction of the mechanical clock 1 where the back cover of the outer case is located.

[0032] Mechanical watch 1 is a watch that uses a mainspring 11 as a power source and controls the movement of the mainspring 11 by an escapement mechanism 20 and a regulating mechanism 30, and also drives the hands. Mechanical watch 1 consists of a base plate 10 into which the mechanisms for driving the hands are incorporated, housed in an outer case. In the first embodiment, the outer case is not shown. The crown, which is located on the side of the outer case, is also not shown. The crown is attached to the end of the winding stem 2 shown in Figure 1.

[0033] [Overall Configuration Overview: Drive Mechanism Configuration] This section describes the general outline of the drive mechanism of the mechanical clock 1. In the first embodiment, the mechanism including the power source, the mainspring 11, the gear train 12, and the pointer shaft 13 is referred to as the "drive mechanism." In Figure 2, only the second hand 131 of the pointers is shown. The drive mechanism shown in Figure 2 is an example and is not limited to this; it may also include gears other than those shown.

[0034] The mainspring 11 is housed in a barrel 110, which is made of a metal strip and has multiple teeth formed on its outer circumference. The barrel 110 is disc-shaped and has a cavity formed inside that houses the mainspring 11. The inner end of the mainspring 11 is fixed to the barrel arbor (not shown), which is a rotating shaft located 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 the user, the winding stem 2 rotates. As the winding stem 2 rotates, the mainspring 11 is wound up. The wound mainspring 11 is then unwound by its elastic force. The barrel 110 rotates in conjunction with the movement of the mainspring 11 during this process.

[0035] The gear train 12 includes at least a second wheel 122, a third wheel 123, and a fourth wheel 124. The second wheel 122 includes a pinion that engages with several teeth formed on the barrel 110, which functions as the first wheel, a pivot shaft, and several teeth, and transmits the rotation of the barrel 110 to the third wheel 123. The pivot shaft of the second wheel 122 is the pointer shaft of the minute hand (not shown). The third wheel 123 includes a pinion that engages with several teeth of the second wheel 122, a pivot shaft, and several teeth, and transmits the rotation of the second wheel 122 to the fourth wheel 124. The fourth wheel 124 includes a pinion that engages with several teeth of the third wheel 123, a pivot shaft, and several teeth, and transmits the rotation of the third wheel 123 to the escapement mechanism 20. As shown in Figure 2, the pivot shaft of the fourth wheel 124 is the pointer shaft 13 of the second hand 131.

[0036] [Overall Configuration Overview: Configuration of escapement mechanism 20 and speed control mechanism 30, and overview of their operation] Next, the escapement mechanism 20 and the regulating mechanism 30 will be described. Power from the mainspring 11 is transmitted to the escapement mechanism 20 and the regulating mechanism 30 through the gear train 12. The escapement mechanism 20 consists of an escape wheel 21 and an anchor 22. The regulating mechanism 30 consists of a balance wheel 31 and a hairspring 32. The regulating mechanism 30 is sometimes called the balance wheel.

[0037] The escape wheel 21 is a component that, by meshing with the anchor 22, receives the rhythm ticked by the speed control mechanism 30 from the anchor 22 and converts it into regular reciprocating motion. The escape wheel 21 includes a pinion that meshes with multiple teeth of the fourth wheel 124, a rotating shaft, and multiple teeth. As shown in Figure 2, the multiple teeth of the escape wheel 21 are formed with wider spacing in the circumferential direction than the teeth of each gear of the gear train 12.

[0038] The anchor 22 rotates in both forward and reverse directions around the anchor pivot 221 shown in Figure 4 as its axis of rotation. The anchor 22 extends from the anchor pivot 221 toward the center of the balance wheel 31 (balance pivot 311) and has a rod portion 222 that strikes a bobblehead (not shown) that rotates together with the balance pivot 311. The bobblehead is fixed to the balance pivot 311.

[0039] Furthermore, the anchor 22 has a first arm 223 to which a pawl 223a that strikes against multiple teeth of the escape wheel 21 is attached, and a second arm 224 that extends in the opposite direction to the first arm 223 and to which a pawl 224a that strikes against multiple teeth of the escape wheel 21 is attached. The pawls 223a and 224a may be made of a stone such as sapphire.

[0040] The balance wheel 31 rotates in both forward and reverse directions around the balance shaft 311 as its center of rotation, power transmitted by the gear train 12. In the following explanation, the forward rotation may be referred to as "forward rotation," and the reverse rotation as "reverse rotation."

[0041] As shown in Figure 3, the balance wheel 31 may have a circular outer shape and a partial notch. However, the shape of the balance wheel 31 shown in Figure 3 is just an example, and it may have parts with different diameters. The balance shaft 311 is supported by the support member 33 shown in Figure 3.

[0042] The hairspring 32 undergoes expansion and contraction (elastic deformation) to cause the balance wheel 31 to rotate in forward and reverse directions. The hairspring 32 is spiral-shaped, with its inner end fixed to the balance staff 311 and its outer end fixed to the hairspring support 34. The hairspring support 34 is fixed to the base plate 10 together with the support member 33. Furthermore, as shown in Figure 3, the hairspring support 34 is provided sandwiched between the support member 33 and the frame member 35.

[0043] The escape wheel 21 rotates in conjunction with the rotation of the fourth wheel 124. As the escape wheel 21 rotates, it collides with the pawl 223a of the anchor 22, causing the anchor 22 to rotate around the anchor stem 221. The rotating shaft 222 of the anchor 22 collides with the balance stone fixed to the balance stem 311, causing the balance wheel 31 to rotate. As the balance wheel 31 rotates, the pawl 224a of the anchor 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 pawl 223a of the anchor 22 is released, and the escape wheel 21 rotates again. As will be described later, since the balance wheel 31 is designed to make one back-and-forth motion in 2 seconds, the escape wheel 21 makes one step of motion per second.

[0044] In the first embodiment, a resin material with a low Young's modulus was used as the material for the hairspring 32. This makes it possible to achieve slower vibration of the balance wheel 31 compared to when it is made of a metal material. If slower vibration were to be achieved with a metal hairspring, the cross-sectional area of ​​the hairspring 32 would have to be reduced to a level that is difficult to process, or the length of the hairspring would have to be increased to a level that is difficult to handle.

[0045] In the first embodiment, a resin with a Young's modulus of approximately 5 [GPa] was used as the material for the hairspring 32. Specifically, polyester was used as the material for the hairspring 32. The hairspring 32 made of resin material may be manufactured, for example, by laser processing. The Young's modulus of a typical metal hairspring is about 200 [GPa]. The Young's modulus shown here is just an example, and the Young's modulus of the hairspring 32 should preferably be 20 [GPa] or less. That is, the Young's modulus of the hairspring 32 should preferably be one-tenth or less of the Young's modulus of a metal hairspring. More preferably, the Young's modulus of the hairspring 32 should be 10 [GPa] or less. That is, the Young's modulus of the hairspring 32 should preferably be one-twentieth or less of the Young's modulus of a metal hairspring. Furthermore, as long as the Young's modulus is 20 [GPa] or less, the hairspring 3 may be made of materials such as paper or wood.

[0046] Furthermore, in the first embodiment, the rotation angle [deg] of the balance wheel 31 and the permanent magnet 41 when the hairspring 32 is in the neutral position of elastic deformation is set to 0°. The neutral position of elastic deformation of the hairspring 32 is, in other words, the position where the hairspring 32 is at its natural length. Also, power from the power spring 11 is supplied to the balance wheel 31 when the hairspring 32 is in the neutral position of elastic deformation. That is, the balance wheel 31 and the permanent magnet 41 are in a power supply position where power from the power spring 11 is supplied when the rotation angle is 0°. Furthermore, as will be described later, in the first embodiment, the permanent magnet 41 is in a magnetically balanced position when the rotation angle is 0°.

[0047] Furthermore, in the first embodiment, the balance wheel 31 was designed to be driven within a rotation angle range of 340° to -340°. Therefore, the permanent magnet 41 is also driven within a rotation angle range of 340° to -340°. However, this is just one example, and the range of movement of the balance wheel 31 should preferably be greater than or equal to a rotation angle range of 270° to -270°. By increasing the range of movement of the balance wheel 31 to a certain extent, it is possible to achieve low-speed vibration of the balance wheel 31.

[0048] As explained above, the regulating mechanism 30 causes the balance wheel 31 to repeatedly rotate in forward and reverse directions (reciprocating motion) at a constant period by the expansion and contraction of the hairspring 32. The escapement mechanism 20 continuously applies force to the balance wheel 31 to cause it to reciprocate. Through this configuration and operation, the hands such as the second hand 131 are driven.

[0049] [Overall Configuration Overview: Configuration of the Rate Adjustment Mechanism 40] Next, the configuration of the rate adjustment means 40 will be described. The mechanical clock 1 according to the first embodiment includes a drive mechanism, an escapement mechanism 20, a regulating mechanism 30, and a rate adjustment means 40.

[0050] The rate adjustment means 40 comprises a permanent magnet 41, a soft magnetic core 42 (sometimes called a stator), a coil 43, and various circuits (see Figure 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 the reference frequency of a crystal oscillator 70, which is a reference signal source. In the first embodiment, as shown in Figure 8 and other figures described later, the output period of the reference signal OS is set to an output period ts having a predetermined width. In the first embodiment, a crystal oscillator 70 was used as the reference signal source to achieve high frequency accuracy, but it is not limited to this, and for example, a CR oscillator composed of a capacitor and a resistor may be used.

[0051] Although not shown in the diagram, the coil 43 is preferably positioned so as to overlap with the inner frame, which is located inside the outer casing, 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 positioned within that notch.

[0052] The permanent magnet 41 is a bipolar, disc-shaped rotating body, magnetized radially with a north pole and a south pole. That is, the permanent magnet 41 is a magnet that includes a north pole portion 411 and a south pole portion 412.

[0053] The permanent magnet 41 is attached to the balance staff 311, which is the rotation axis of the balance wheel 31, and is configured to rotate in the forward and reverse directions in accordance with the forward and reverse rotational motion of the balance wheel 31 (balance staff 311). That is, the permanent magnet 41 rotates in the forward and reverse directions 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 is preferably fixed to the balance staff 311 by press-fitting or adhesive.

[0054] The permanent magnet 41 is preferably an isotropic magnet whose easy magnetization axis is oriented in a random direction. Furthermore, the permanent magnet 41 is preferably magnetized by applying a magnetic field using a Helmholtz coil or the like while attached to the tension rod 311. By employing this magnetization method, the magnetization direction of the permanent magnet 41 can be precisely aligned.

[0055] The soft magnetic core 42 is made of a soft magnetic material and, as shown in Figure 4, has a first magnetic portion 421 including a first end portion 421a provided along the outer circumference of the permanent magnet 41, and a second magnetic portion 422 including a second end portion 422a provided along the outer circumference of the permanent magnet 41, and together with the coil 43, constitutes a magnetic circuit. Both the first end portion 421a and the second end portion 422a have a semicircular inner surface shape and are arranged facing each other via the permanent magnet 41.

[0056] In the first embodiment, when the hairspring 32 is in the neutral position of elastic deformation, the permanent magnet 41 has its north pole portion 411 positioned on the second magnetic portion 422 side and its south pole portion 412 positioned on the first magnetic portion 421 side (see enlarged view of Figure 4). The arrangement of the north pole portion 411 and the south pole portion 412 may be reversed, but in that case, the winding direction of the coil 43 must be reversed compared to the first embodiment.

[0057] Furthermore, as shown in Figure 3, the soft magnetic core 42 is fixed to the support member 33 by a fixing device consisting of a pipe 33a and a screw 33b. With this configuration, the soft magnetic core 42 is assembled to the base plate 10 together with the support member 33.

[0058] Furthermore, among the components assembled to the base plate 10, it is desirable that components located close to the permanent magnet 41, excluding the soft magnetic core 42, such as the support member 33, hairspring holder 34, frame member 35, hairspring 32, and balance wheel 31, be made of non-magnetic material so as not to affect the forward and reverse rotational motion of the speed control mechanism 30 or the back electromotive force generated by the coil 43 described later.

[0059] Furthermore, as shown in Figure 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 positioned opposite the first welded portion 423 via a permanent magnet 41. It is preferable that the first welded portion 423 and the second welded portion 424 be formed within a gap that physically separates the first end 421a and the second end 422a.

[0060] The permanent magnet 41 is in a magnetically balanced position when its magnetization direction is perpendicular to the opposing direction of the first weld 423 and the second weld 424. In the first embodiment, the magnetically balanced position of the permanent magnet 41 is set to a rotation angle of 0°. At this position, the holding torque of the permanent magnet 41 is approximately 0. The opposing direction of the first weld 423 and the second weld 424 is the direction in which the straight line connecting the first weld 423 and the second weld 424 extends, as shown in Figure 4. As shown in Figure 4, in the first embodiment, notches are formed on the inner circumferential surfaces of the first end 421a and the second end 422a of the soft magnetic core 42. Specifically, notches n11 and n12 are formed on the first end 421a. In addition, a notch n21 is formed on the second end 422a opposite to notch n11 via the permanent magnet 41, and a notch n22 is formed opposite to notch n12 via the permanent magnet 41. The formation of this notch reduces the magnetic influence that the permanent magnet 41 has on the soft magnetic core 42.

[0061] In the first embodiment, as shown in Figure 4, an example was shown in which the first end 421a and the second end 422a of the soft magnetic core 42 are integrated via a first weld 423 and a second weld 424, but the embodiment is not limited to this. For example, there may be no first weld 423 and a second weld 424, and the magnetic coupling between the first end 421a and the second end 422a may be separated by a gap. Furthermore, the embodiment is not limited to one 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 constricted portion which is a separation portion.

[0062] Furthermore, as shown in Figure 5, the rate adjustment means 40 includes a control circuit 44, a rotation detection circuit 45, a speed control pulse output circuit 46, a frequency divider circuit 47, an oscillation circuit 48, and a damping circuit 80. In Figure 5, the permanent magnet 41, soft magnetic core 42, and coil 43 described above are omitted from the illustration. Note that the configuration of the rate adjustment means 40 shown in Figure 5 is just one example. The rate adjustment means 40 does not need to independently provide each circuit shown in Figure 5, but only needs to be capable of realizing each of the functions described below.

[0063] The control circuit 44 is a circuit that controls the operation of each circuit included in the rate adjustment means 40. In particular, as described later, the control circuit 44 controls the braking force that brakes the permanent magnet 41 by controlling the speed control pulse output circuit 46 and the braking circuit 80.

[0064] 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 oscillation signal output from the oscillation circuit 48. By dividing the oscillation signal based on the crystal oscillator 70, the frequency divider circuit 47 generates a reference signal OS that is output approximately every 1000 ms. However, it is not limited to this, and the reference signal OS may be output every 2000 ms or every 3000 ms. In other words, the reference signal OS only needs to be output every second. Furthermore, it is not limited to this, and the reference signal OS only needs to correspond to the period of the speed control mechanism 30.

[0065] The rotation detection circuit 45 detects a detection signal based on the voltage waveform generated in the coil 43 due to the motion of the permanent magnet 41. In the first embodiment, the signal detected by the rotation detection circuit 45 when a back electromotive force (EMF) of a predetermined threshold Vth or higher is generated is defined as the detection signal DE. In the first embodiment, as shown in Figure 8 below, the predetermined threshold Vth is set to 0.5[V]. However, the back EMF may momentarily exceed the threshold Vth due to external factors such as shock or other noise. To avoid false detections caused by such noise, for example, rotation detection may be performed at intervals of 32[μs], and the starting point for speed control may be the timing when the detection signal DE has been detected two or more predetermined times. However, this is not limited to this, and it may be appropriately determined based on the rotation detection interval, the number of times the detection signal DE has been detected continuously, the number of times the detection signal has been accumulated, etc.

[0066] 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 rotation detection circuit 45. Specifically, it compares the detection timing of the detection signal DE detected by the rotation detection circuit 45 with the output timing of the reference signal of approximately 1000 Hz. If there is a discrepancy in their timings, the speed control pulse output circuit 46 outputs a speed control pulse to bring the period during which the detection signal DE is detected closer to 1000 ms (= 1 second).

[0067] The speed control pulse is output by energizing coil 43. Therefore, the speed control pulse output circuit 46 should energize coil 43 so that a torque acts to slow down the movement of the permanent magnet 41 when the detection period of the detection signal DE is faster than the reference signal, and energize coil 43 so that a torque acts to speed up the movement of the permanent magnet 41 when the detection period of the detection signal DE is slower than the reference signal. The speed control pulse output when coil 43 is energized so that a torque acts to slow down the movement of the permanent magnet 41 becomes a braking force that brakes the movement of the permanent magnet 41. Details of the rate adjustment control, including the timing of the speed control pulse output, will be described later.

[0068] The speed control pulse output circuit 46 is preferably configured to output multiple speed control pulses with different output periods (pulse widths). Furthermore, the speed control pulse output circuit 46 is preferably configured to output multiple speed control pulses with different output voltages.

[0069] [Overall Configuration Overview: Speed ​​Control Mechanism 30 as a Generator] Mechanical clock 1 has a power generation function using the principle of electromagnetic induction. In the first embodiment, the speed regulating mechanism 30 functions as part of the generator. Specifically, the permanent magnet 41 rotates in the forward and reverse directions in conjunction with the forward and reverse rotational motion of the balance wheel 31, and power is generated by the current produced in the coil 43 based on the change in the magnetic field caused by the motion of the permanent magnet 41. The power extracted by this operating principle is used to start the power supply circuit 60. Once the power supply circuit 60 is started, the control circuit 44 can be driven. Because of this configuration, in the first embodiment, the control circuit 44 can be driven without providing a separate power source such as a battery.

[0070] 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 motion of the balance wheel of the speed control mechanism 30. The power supply circuit 60 is a circuit including, for example, a capacitor, and stores power to drive the control circuit 44 based on the current rectified by the rectifier circuit 50.

[0071] [Details on rate adjustment control] The details of the rate adjustment control in the first embodiment will be described below with reference to Figures 6, 7A, and 7B.

[0072] Figure 6 illustrates the relationship between the operation of the balance wheel in the first embodiment and the back electromotive force generated in the coil. In the upper graph of Figure 6, the vertical axis represents the angular velocity of the balance wheel 31 [rad / s], and the horizontal axis represents the measurement time [s]. In the middle graph of Figure 6, the vertical axis represents the rotation angle of the balance wheel 31 [deg], and the horizontal axis represents the measurement time [s]. In the lower graph of Figure 6, the vertical axis represents the back electromotive force generated in the coil 43 [V], and the horizontal axis represents the measurement time [s]. Furthermore, each graph shown in Figure 6 illustrates an example in which the movement of the balance wheel 31 (permanent magnet 41) was measured for 4 seconds.

[0073] In the first embodiment, the speed control pulse output circuit 46 outputs a speed control pulse, thereby controlling the movement of the permanent magnet 41 and adjusting the rate by controlling the movement of the balance wheel 31.

[0074] [Details on rate adjustment control: Output timing of the speed control pulse] Here, when the angular velocity of the permanent magnet 41 is high, it is difficult to adjust the rate at the desired timing. This is because when the angular velocity of the permanent magnet 41 is high, there is a high possibility that the timing of the speed control pulse output will be off. The angular velocity of the permanent magnet 41 is high when a large back electromotive force is generated in the coil 43. That is, it is the timing when the rotation detection circuit 45 detects the detection signal DE.

[0075] Therefore, in the first embodiment, it is preferable to output a speed control pulse during the forward and reverse rotational motions of the permanent magnet 41, specifically while the permanent magnet 41 rotates in the reverse direction from a rotation angle of 180° to 0°, and while it rotates in the forward direction from a rotation angle of -180° to 0°. In other words, it is preferable to output a speed control pulse during the period before the balance wheel 31 is supplied with power from the power spring 11. This makes it possible to output a speed control pulse when the angular velocity of the permanent magnet 41 is relatively slow. It is preferable to output the speed control pulse while avoiding periods when power generation is easily obtained. As will be described later, periods when power generation is easily obtained are the period when the permanent magnet 41 rotates in the forward direction from a rotation angle of 0° to 180°, and the period when it rotates in the reverse direction from 0° to -180°.

[0076] By adopting this configuration, it is possible to suppress deviations in the output timing of the speed control pulse. As a result, rate accuracy can be maintained. In Figure 6, the timing of rate adjustment is shown in a band-shaped region. As shown in the upper graph of Figure 6, rate adjustment is performed during periods when the angular velocity of the permanent magnet 41 is slow.

[0077] [Details on rate adjustment control: Coil terminal where the speed control pulse is output] Figures 7A and 7B illustrate the control of the movement of a permanent magnet by a speed control pulse in the first embodiment. In the first embodiment, as shown in Figure 7A, when a speed control pulse is output to the first terminal O1 of the coil 43, the first end 421a is defined to have the polarity of the south pole and the second end 422a to have the polarity of the north pole. On the other hand, as shown in Figure 7B, when a speed control pulse is output to the terminal O2 of the coil 43, the first end 421a is defined to have the polarity of the north pole and the second end 422a to have the polarity of the south pole. Note that if the winding direction of the coil 43 is reversed, the polarity of the first end 421a and the second end 422a will be reversed.

[0078] Figure 7A shows an example in which a speed control pulse is output to the coil 43 when the permanent magnet 41 rotating in the positive direction is at a rotation angle of -90°, and when the permanent magnet 41 rotating in the reverse direction is at a rotation angle of 90°.

[0079] As shown in Figure 7A, when the permanent magnet 41 rotates in the positive direction from a rotation angle of -90°, if a speed control pulse is output to the first terminal O1 of the coil 43, the permanent magnet 41 will experience a repulsive force from the soft magnetic core 42. In other words, the rotation of the permanent magnet 41 in the positive direction will be braked. On the other hand, when the permanent magnet 41 rotates in the reverse direction from a rotation angle of 90°, if a speed control pulse is output to the first terminal O1 of the coil 43, the permanent magnet 41 will experience a repulsive force from the soft magnetic core 42. In other words, the rotation of the permanent magnet 41 in the reverse direction will be braked.

[0080] Furthermore, as shown in Figure 7B, when the permanent magnet 41 rotates in the positive direction from a rotation angle of -90°, if a speed control pulse is output to the second terminal O2 of the coil 43, the permanent magnet 41 will receive an attractive force from the soft magnetic core 42. In other words, the rotation of the permanent magnet 41 in the positive direction will be accelerated. On the other hand, when the permanent magnet 41 rotates in the reverse direction from a rotation angle of 90°, if a speed control pulse is output to the second terminal O2 of the coil 43, the permanent magnet 41 will receive an attractive force from the soft magnetic core 42. In other words, the rotation of the permanent magnet 41 in the reverse direction will be accelerated.

[0081] Thus, in the first embodiment, regardless of whether the permanent magnet 41 is rotating in the forward or reverse direction, the rotation of the permanent magnet 41 can be weakened by outputting a speed control pulse to the first terminal O1, while the rotation of the permanent magnet 41 can be strengthened by outputting a speed control pulse to the second terminal O2.

[0082] In other words, regardless of whether the permanent magnet 41 is rotating in the forward or reverse direction, to adjust the rate to slow down, you only need to energize the first terminal O1, and to adjust the rate to advance, you only need to energize the second terminal O2.

[0083] [Braking control] The braking control in the first embodiment will now be described. In the first embodiment, braking control is a control that generates a braking force so as to adjust the vibration frequency of the balance wheel 31 to a predetermined value.

[0084] In the mechanical clock 1, the faster the balance wheel 31 moves, that is, the higher the oscillation frequency of the balance wheel 31, the more easily the power-transmitting mechanisms (for example, the escape wheel 21 and the anchor 22) wear out, reducing their durability. Therefore, in the first embodiment, as described above, a resin material with a low Young's modulus is used for the hairspring 32. However, the balance wheel 31 operates by utilizing the mechanical movements of the power mainspring 11 and the hairspring 32, and there is room for further ingenuity in slowing down its movement.

[0085] Therefore, in the first embodiment, a configuration was adopted in which a braking force is generated to brake the permanent magnet 41 at each cycle of the balance wheel 31. The following describes various embodiments and modifications of the braking control in the first embodiment.

[0086] [Braking control: First embodiment] Figure 8 is a timing chart showing an example of braking control in the first embodiment of the first embodiment. The upper part of Figure 8 shows the voltage waveform generated in coil 43 when braking control of the first embodiment is not performed. The middle part of Figure 8 shows the voltage waveform generated in coil 43 when braking control of the first embodiment is performed. The lower part of Figure 8 shows an example of the detection timing of the detection signal DE, the output timing of the reference signal OS, and the output timing of the speed control pulse output to the first terminal O1 of coil 43 in the first embodiment.

[0087] In the first embodiment, as shown in the lower part of Figure 8, a speed control pulse with pulse width (output period) fp1 is output to the first terminal O1 when time tp1 has elapsed since the detection signal DE was detected. Furthermore, the speed control pulse is output to the first terminal O1 each time the detection signal DE is detected.

[0088] Thus, in the first embodiment, regardless of whether the output timing of the detection signal DE is earlier or later than the output timing of the reference signal OS, the coil 43 is energized so that a torque acts in a direction that reduces the vibration frequency of the permanent magnet 41 (ten-ring 31) at each cycle of the permanent magnet 41 (ten-ring 31). This makes it possible to reduce the vibration frequency of the ten-ring 31. Therefore, in the first embodiment shown in the middle and lower parts of Figure 8, the period in which the detection signal DE is detected is longer than in the example without braking control shown in the upper part of Figure 8. In other words, in the first embodiment shown in the middle and lower parts of Figure 8, the vibration frequency is lower than in the example without braking control shown in the upper part of Figure 8.

[0089] The magnitude of the braking force is determined by the output duration and output voltage of the speed control pulse. In the first embodiment, the output duration fp1 and output voltage of the speed control pulse are preferably set in advance so that the vibration frequency of the balance wheel 31 becomes a desired frequency.

[0090] As described above, by utilizing the braking control of the first embodiment, the oscillation frequency of the balance wheel 31 can be adjusted to a frequency lower than the oscillation frequency of the balance wheel 31 obtained according to the physical structure of the mechanical clock 1.

[0091] [Braking control: Second embodiment] Next, the braking control in the second embodiment of the first embodiment will be described with reference to Figures 9 and 10. Figure 9 is a circuit diagram of the first embodiment. Figure 10 is a timing chart showing an example of braking control in the second embodiment of the first embodiment. The upper part of Figure 10 shows the voltage waveform generated in the coil 43 when the braking control of the second embodiment is performed. The lower part of Figure 10 shows the detection timing of the detection signal DE, the output timing of the reference signal OS, and the operation timing of the electromagnetic brake in the second embodiment. In the first embodiment, the electromagnetic brake refers to the braking force obtained by short-circuiting 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 opposes the change in magnetic flux generated in the coil 43 as the permanent magnet 41 rotates.

[0092] In the first embodiment described above, an example was given in which the permanent magnet 41 is braked by a speed control pulse. However, the power consumption is high when controlling the terminals of the coil 43 to be energized. Therefore, in the braking control of the second embodiment, an electromagnetic brake with relatively low power consumption was used as a means to generate braking force.

[0093] First, the circuit configuration in the first embodiment will be described with reference to Figure 9.

[0094] As shown in Figure 9, transistors TP1 and TP2 are connected to the first terminal O1 and the second terminal O2 of the coil 43, respectively. The back electromotive force generated in the coil 43 is input to transistors TP1 and TP2, and the rotation detection circuit 45 detects a detection signal based on this. That is, by turning on transistor TP2 at a predetermined timing, the induced voltages generated at the first terminal O1 and the second terminal O2 corresponding to those transistors can be extracted as a voltage signal, which is a detection signal.

[0095] Furthermore, transistors P11 and P12 are connected to the first terminal O1 of coil 43, and transistors P21 and P22 are connected to the second terminal O2 of coil 43. Transistors P11, P12, P21, and P22 are controlled ON / OFF by speed control pulses from the speed control pulse output circuit 46. During power generation, the gate terminals of transistors P11, P12, P21, and P22 are turned OFF. At this time, it is also preferable that the braking circuit 80 does not generate braking force. That is, it is preferable to turn OFF transistors DB1 and DB2, which will be described later. In that state, the rectifier circuit 50 is formed by transistors TP1 and TP2 and diode D. As the permanent magnet 41 rotates in forward and reverse directions, current flows through coil 43 and capacitor C is charged. When a certain amount of charge is stored in capacitor C, the power supply circuit 60 is started. Then, when the power supply circuit 60 is activated, the control circuit 44 is activated, and the control circuit 44 controls each circuit included in the rate adjustment means 40.

[0096] Furthermore, transistor DB1 is connected to the first terminal O1 of coil 43, and transistor DB2 is connected to the second terminal O2 of coil 43. Transistors DB1 and DB2 constitute the damping circuit 80 shown in Figure 5. The damping circuit 80 is a circuit that generates a damping force that reduces the vibration frequency of the permanent magnet 41 by short-circuiting the first terminal O1 and the second terminal O2. In Figure 5, the damping circuit 80 is shown as being included as part of the rate adjustment means 40, but it is not limited to this configuration.

[0097] In the second embodiment, as shown in the lower part of Figure 10, the electromagnetic brake DB with an operating period of b1 is activated when time tb1 has elapsed since the detection signal DE was detected. Furthermore, the electromagnetic brake DB is activated each time the detection signal DE is detected.

[0098] Thus, in the second embodiment, regardless of whether the output timing of the detection signal DE is earlier or later than the output timing of the reference signal OS, the electromagnetic brake is applied at each cycle of the permanent magnet 41 (balance wheel 31). This makes it possible to reduce the vibration frequency of the balance wheel 31.

[0099] The magnitude of the braking force is determined by the duration of the electromagnetic brake's operation. In the second embodiment, the duration b1 of the electromagnetic brake's operation is preferably set in advance so that the vibration frequency of the balance wheel 31 becomes a desired frequency.

[0100] As described above, by utilizing the braking control of the second embodiment, the oscillation frequency of the balance wheel 31 can be adjusted to a frequency lower than the oscillation frequency of the balance wheel 31 obtained according to the physical structure of the mechanical clock 1, similar to the first embodiment. Furthermore, in the second embodiment, power consumption in the braking control can be reduced compared to the first embodiment.

[0101] [Braking control: Third embodiment] Next, the braking control in the third embodiment of the first embodiment will be described with reference to Figure 11. Figure 11 is a timing chart showing an example of braking control in the third embodiment of the first embodiment. The upper part of Figure 11 shows the voltage waveform generated in the coil 43 when the braking control of the third embodiment is performed. The lower part of Figure 11 shows the detection timing of the detection signal DE, the output timing of the reference signal OS, the output timing of the speed control pulse output to the first terminal O1 of the coil 43, and the operation timing of the electromagnetic brake in the third embodiment.

[0102] In the third embodiment, an example is described in which the vibration frequency of the balance wheel 31 is reduced by using in combination the speed control pulse described in the first embodiment and the electromagnetic brake described in the second embodiment.

[0103] In the third embodiment, as shown in the lower part of Figure 11, a speed control pulse with pulse width fp1 is output to the first terminal O1 at a time tp1 elapsed after the detection signal DE is detected. Furthermore, the electromagnetic brake DB is activated during the period after time tb1 has elapsed since the detection signal DE was detected but when the speed control pulse is not being output. In the third embodiment, the operating period of the electromagnetic brake DB is defined as b1. That is, the actual operating time of the electromagnetic brake DB is the operating period b1 minus the pulse width fp1.

[0104] As explained with reference to Figure 9, the speed control pulse is generated by energizing the terminals of the coil 43, and the electromagnetic brake is generated by short-circuiting the terminals of the coil 43; therefore, they cannot be generated simultaneously. For this reason, in the third embodiment, the control circuit 44 switches the transistor switch so that the speed control pulse and the electromagnetic brake are generated in a nested manner (see the lower part of Figure 11).

[0105] In the third embodiment, by using both a speed control pulse and an electromagnetic brake, it is possible to maintain a large braking force while suppressing power consumption. Specifically, by controlling the system to output a speed control pulse when the electromagnetic brake DB is not acting, a large braking force can be generated, while by activating the electromagnetic brake DB when the speed control pulse is not being output, braking force can be generated while suppressing power consumption. As a result, even if the oscillation frequency of the balance wheel 31 obtained according to the physical structure of the mechanical clock 1 is high, it is possible to adjust the oscillation frequency of the balance wheel 31 to a low frequency while suppressing power consumption.

[0106] [Timing of electromagnetic brake action] Next, with reference to Figure 12, the details of the timing of the electromagnetic brake's operation will be explained. Figure 12 is a diagram illustrating the timing of the electromagnetic brake's operation in the first embodiment. The upper part of Figure 12 shows the time change in the rotation angle of the balance wheel 31, and the lower part of Figure 12 shows the time change in the back electromotive force.

[0107] As described above, the vibration frequency of the balance wheel 31 can be reduced by applying the electromagnetic brake. However, if the vibration frequency of the balance wheel 31 decreases, the amount of electricity generated by the rotation of the permanent magnet 41 also decreases. Therefore, in the first embodiment, the electromagnetic brake was applied at a time that avoids the timing when power generation occurs.

[0108] As shown in Figure 12, in the first embodiment, a positive rise in the back electromotive force detected by the coil 43 occurs when the rotational speed of the balance wheel 31 reaches its maximum value while the balance wheel 31 rotates in the positive direction from 0° to 180° and while the balance wheel 31 rotates in the reverse direction from 0° to -180°. In other words, power can be generated most efficiently by extracting power when the rotational angle of the balance wheel 31 rotates from 0° to 180° and from 0° to -180°. The period shown by the dashed strip in Figure 12 is the period during which power can be generated efficiently. In order to avoid a decrease in the vibration frequency of the balance wheel 31 during this period, it is preferable to apply the electromagnetic brake after the rotational speed of the balance wheel 31 reaches its maximum value, i.e., avoiding the period shown by the dashed strip in Figure 12. By performing such control, braking using the electromagnetic brake can be performed while ensuring the amount of power generated.

[0109] [Braking control in case of rate deviation] Next, referring to Figures 13 to 20, we will explain the braking control in the event of a rate deviation. That is, we will explain the braking control when the rate advances or when the rate lags behind. In this explanation, braking control is a part of the rate adjustment control.

[0110] [Braking control in case of rate deviation: Fourth embodiment] First, with reference to Figure 13, braking control in the case of advanced rate will be explained. Figure 13 is a timing chart showing an example of braking control in the fourth embodiment of the first embodiment. The upper part of Figure 13 shows the voltage waveform generated in coil 43 when braking control of the fourth embodiment is performed. The lower part of Figure 13 shows the detection timing of the detection signal DE, the output timing of the reference signal OS, the output timing of the speed control pulse output to the first terminal O1 of coil 43, and the operation timing of the electromagnetic brake in the fourth embodiment.

[0111] In the fourth embodiment, as shown in Figure 13, we will describe an example in which the detection timing of the second detection signal DE detected after the start of measurement is earlier than the output timing of the reference signal OS. In other words, we will describe an example in which the vibration frequency of the balance wheel 31 increases and the rate advances.

[0112] If the rate of motion deviates in the direction of advancement, it is desirable to generate a braking force (second braking force) greater than the braking force (first braking force) generated when the rate of motion is not deviated. Therefore, in the fourth embodiment, the output period (pulse width) of the speed control pulse output to the first terminal O1 after the rate of motion deviation occurs is lengthened. Specifically, as shown in the lower part of Figure 13, when the detection timing of the detection signal DE becomes earlier than the output timing of the reference signal OS, the output period of the speed control pulse output to the first terminal O1 after the detection of the detection signal DE is set to p1 (>fp1). Note that the output period fp1 is the output period of the speed control pulse when there is no rate of motion deviation, similar to the example shown in Figure 8, etc.

[0113] [Braking control in case of rate deviation: Fifth embodiment] Referring to Figure 14, braking control in the case of a delay will be explained. Figure 14 is a timing chart showing an example of braking control in the fifth embodiment of the first embodiment. The upper part of Figure 14 shows the voltage waveform generated in coil 43 when braking control of the fifth embodiment is performed. The lower part of Figure 14 shows the detection timing of the detection signal DE, the output timing of the reference signal OS, the output timing of the speed control pulse output to the first terminal O1 of coil 43, and the operation timing of the electromagnetic brake in the fifth embodiment.

[0114] In the fifth embodiment, as shown in the lower part of Figure 14, we will describe an example in which the detection timing of the second detection signal DE detected after the start of measurement is later than the output timing of the reference signal OS. In other words, we will describe an example in which the vibration frequency of the balance wheel 31 becomes low and the rate slows down.

[0115] If the rate of motion deviates in the direction of slowing down, it is desirable to reduce the braking force that brakes the permanent magnet 41. Therefore, in the fifth embodiment, after the rate of motion deviation occurs, the speed control pulse is not output to the first terminal O1. Specifically, if the detection timing of the detection signal DE becomes later than the output timing of the reference signal OS, the braking control performed after the detection signal DE is detected is to not output the speed control pulse to the first terminal O1.

[0116] In the fifth embodiment, the electromagnetic brake is activated each time the detection signal DE is detected. Although braking force is generated when the electromagnetic brake is activated, the overall braking force can be reduced because no speed control pulse is output to the first terminal O1. As a result, rate deviation can be suppressed.

[0117] [Braking control in case of rate deviation: Sixth embodiment] Referring to Figure 15, braking control in the case of a lag will be explained. Figure 15 is a timing chart showing an example of braking control in the sixth embodiment of the first embodiment. The upper part of Figure 15 shows the voltage waveform generated in coil 43 when braking control of the sixth embodiment is performed. The lower part of Figure 15 shows the detection timing of the detection signal DE, the output timing of the reference signal OS, the output timing of the speed control pulse output to the first terminal O1 and the second terminal O2 of coil 43, and the operation timing of the electromagnetic brake in the sixth embodiment.

[0118] In the sixth embodiment, similar to the fifth embodiment described above, we will describe an example in which the detection timing of the second detection signal DE detected after the start of measurement is later than the output timing of the reference signal OS. In other words, we will describe an example in which the vibration frequency of the balance wheel 31 becomes low and the rate slows down.

[0119] If the rate of rotation deviates in the direction of lagging, it is advisable to apply a force to the permanent magnet 41 in the direction of advancing the rate of rotation. Therefore, in the sixth embodiment, after a rate deviation occurs, the output of the speed control pulse to the first terminal O1 is stopped, and a speed control pulse is output to the second terminal O2. Specifically, if the detection timing of the detection signal DE is delayed compared to the output timing of the reference signal OS, as braking control performed after the detection of the detection signal DE, a speed control pulse is output to the second terminal O2 and the electromagnetic brake is applied. Figure 15 shows an example in which a speed control pulse with a pulse width p2 is output to the second terminal O2 after a time tp2 has elapsed since the detection of the detection signal DE. Note that time tp2 may be the same as or different from time tp1. As explained with reference to Figure 7B, the rotation of the permanent magnet 41 can be strengthened by outputting a speed control pulse to the second terminal O2.

[0120] In the sixth embodiment, the electromagnetic brake is activated each time the detection signal DE is detected. The electromagnetic brake's activation generates a braking force. Specifically, a braking force (third braking force) smaller than the braking force (first braking force) generated when the rate is not misaligned is produced. On the other hand, the output of a speed control pulse to the second terminal O2 generates a force that advances the permanent magnet 41. As a result, rate deviation can be suppressed.

[0121] [Flowchart of the first embodiment] Next, the processing flow of the braking control in the first embodiment will be described with reference to Figure 16. Figure 16 is a flowchart showing an example of the braking control in the first embodiment.

[0122] In the first embodiment, after the power supply circuit 60 is activated by the movement of the permanent magnet 41, which generates electricity (Y in ST1), braking control is initiated. Then, after a back electromotive force of Vth or higher is generated, that is, after the rotation detection circuit 45 detects the detection signal DE (Y in ST2), the electromagnetic brake is activated (ST3). In the example shown in Figure 16, the duration of the electromagnetic brake's operation is constant in each cycle.

[0123] Then, the control circuit 44 acquires the time difference between the detection signal DE and the reference signal OS (the amount of deviation in the detection timing of the detection signal DE relative to the output timing of the reference signal OS) (ST4).

[0124] If the time difference is 0 or within a predetermined range (Y in ST5), that is, if no rate deviation occurs, a speed control pulse is output to the first terminal O1 (ST6). The electromagnetic brake is stopped while the speed control pulse is being output. The same applies to ST8 and ST11, which will be described below. Subsequently, if no rate deviation occurs, the same control is repeated each time the detection signal DE is detected (ST2). That is, the braking control of the third embodiment described with reference to Figure 11 is performed.

[0125] If the period difference is outside the predetermined range (N in ST5) and the period difference is positive (ST7), that is, if the rate is advanced, a speed control pulse with a long output period is output to the first terminal O1 (ST8). In other words, the braking control of the fourth embodiment described with reference to Figure 13 is performed.

[0126] If the period difference is outside the predetermined range (N in ST5), and the period difference is negative and the negative amount is within the predetermined range (N in ST7, Y in ST9), no speed control pulse is output to the first terminal O1 (ST10). In other words, the braking control of the fifth embodiment described with reference to Figure 14 is performed.

[0127] If the period difference is outside the predetermined range (N in ST5), and the period difference is negative, and the negative amount is outside the predetermined range (N in ST7, N in ST9), a speed control pulse is output to the second terminal O2 (ST11). In other words, the braking control of the sixth embodiment described with reference to Figure 15 is performed.

[0128] [Differentiation] Next, a modified version of the first embodiment will be described with reference to Figures 17 to 19. Figures 17 to 19 are timing charts showing an example of braking control in a modified version of the first embodiment. Figures 17 to 19 describe an example of braking control performed according to the degree of rate deviation. Specifically, an example is described in which the magnitude of the braking force is varied according to the degree of rate deviation. The magnitude of the braking force is determined by the output period (pulse width) of the speed control pulse output by the speed control pulse output circuit 46, the output voltage of the speed control pulse, and the output period of the electromagnetic brake DB.

[0129] Figures 17 and 18 show examples of cases where the detection timing of the detection signal DE is ahead of the reference signal OS by time t, 2t, and 3t, and cases where the detection timing of the detection signal DE is behind the reference signal OS by time t, 2t, and 3t, respectively.

[0130] In the example shown in FIG. 17, as the step rate advances more, the output period of the speed control pulse output to the first terminal O1 is made longer than the output period fp1 shown in FIG. 8 and the like. Specifically, when the detection timing of the detection signal DE is advanced by a time 3t from the reference signal OS, the output period of the speed control pulse output to the first terminal O1 is set to p21 (>fp1). Also, when the detection timing of the detection signal DE is advanced by a time 2t from the reference signal OS, the output period of the speed control pulse output to the first terminal O1 is set to p22 (<p21). Also, when the detection timing of the detection signal DE is advanced by a time t from the reference signal OS, the output period of the speed control pulse output to the first terminal O1 is set to p23 (<p22).

[0131] Also, in the example shown in FIG. 17, when the step rate is delayed, the output period of the speed control pulse output to the first terminal O1 is made shorter than the output period fp1 shown in FIG. 8 and the like. Also, when the delay becomes even larger, a speed control pulse is output to the second terminal O2, and as the delay becomes larger, the output period of the speed control pulse output to the second terminal O2 is made longer. Specifically, when the detection timing of the detection signal DE is delayed by a time t from the reference signal OS, the output period of the speed control pulse output to the first terminal O1 is set to p24 (<fp1). Also, when the detection timing of the detection signal DE is delayed by a time 2t from the reference signal OS, the output of the speed control pulse to the first terminal O1 is stopped, and a speed control pulse with an output period p25 is output to the second terminal O2. Also, when the detection timing of the detection signal DE is delayed by a time 3t from the reference signal OS, the output of the speed control pulse to the first terminal O1 is stopped, and a speed control pulse with an output period p26 (>p25) is output to the second terminal O2.

[0132] In the example shown in FIG. 18, as the step advance is larger, the output voltage of the speed control pulse output to the first terminal O1 is made larger than the output voltage Vfp1 shown in FIG. 8 and the like. Specifically, when the detection timing of the detection signal DE is advanced by time 3t from the reference signal OS, the output voltage of the speed control pulse output to the first terminal O1 is set to Vp31 (> Vfp1). When the detection timing of the detection signal DE is advanced by time 2t from the reference signal OS, the output voltage of the speed control pulse output to the first terminal O1 is set to Vp32 (> Vp31). When the detection timing of the detection signal DE is advanced by time 3t from the reference signal OS, the output voltage of the speed control pulse output to the first terminal O1 is set to Vp33 (> Vp32).

[0133] Also, in the example shown in FIG. 18, when the step is delayed, the output period of the speed control pulse output to the first terminal O1 is made smaller than the output voltage Vfp1 shown in FIG. 8 and the like. Further, when the delay becomes larger, a speed control pulse is output to the second terminal O2, and as the delay is larger, the output voltage of the speed control pulse output to the second terminal O2 is made larger. Specifically, when the detection timing of the detection signal DE is delayed by time t from the reference signal OS, the output voltage of the speed control pulse output to the first terminal O1 is set to Vp34 (< Vp33). Also, when the detection timing of the detection signal DE is delayed by time 2t from the reference signal OS, the output of the speed control pulse to the first terminal O1 is stopped, and a speed control pulse with an output voltage Vp35 is output to the second terminal O2. Also, when the detection timing of the detection signal DE is delayed by time 3t from the reference signal OS, the output of the speed control pulse to the first terminal O1 is stopped, and a speed control pulse with an output voltage Vp36 (> Vp35) is output to the second terminal O2.

[0134] FIG. 19 shows an example of changing the action period of the electromagnetic brake according to the degree of step deviation. In FIG. 19, examples are shown when the detection timing of the detection signal DE is advanced by time t from the reference signal OS, when the detection timing of the detection signal DE coincides with the output timing of the reference signal OS, and when the detection timing of the detection signal DE is delayed by time t and 2t from the reference signal OS, respectively.

[0135] In the example shown in FIG. 19, when the step rate is advancing, the operation period of the electromagnetic brake is lengthened. Specifically, when the step rate has advanced by time t, the operation period b21 is set to be longer than the operation period b1 when the detection timing of the detection signal DE coincides with the output timing of the reference signal OS.

[0136] Also, in the example shown in FIG. 19, when the step rate is lagging, the operation period of the electromagnetic brake is shortened. Specifically, when the step rate lags by time t, the operation period of the electromagnetic brake is set to b22 (<b1). Also, when the step rate lags by 2t, the operation of the electromagnetic brake is stopped.

[0137] [Flowchart of braking control in the modified example] FIG. 20 is a flowchart showing an example of braking control in a modified example of the first embodiment.

[0138] In FIG. 16 described above, an example of performing braking control according to the deviation between the detection timing of the detection signal DE and the output timing of the reference signal OS is shown. However, the amount of deviation may be accumulated, and braking control may be performed according to the accumulated amount of deviation. Hereinafter, the flow of braking control according to the accumulated amount of deviation will be described. Although illustration is omitted, the step adjustment means 40 may have a counter that accumulates the period difference between the detection signal DE and the reference signal OS (the amount of deviation between the detection timing of the detection signal DE and the output timing of the reference signal OS).

[0139] [[ID=1,8]] In a modified version of the first embodiment, after the power supply circuit 60 is activated by the movement of the permanent magnet 41 (Y in ST1), braking control is started. Then, after a back electromotive force of Vth or higher is generated, that is, after the rotation detection circuit 45 detects the detection signal DE (Y in ST2), the control circuit 44 calculates the time difference between the detection signal DE and the reference signal OS (the amount of deviation in the detection timing of the detection signal DE relative to the output timing of the reference signal OS) and accumulates the time difference (ST21). Although not shown in the figures, the rate adjustment means 40 may have a counter which is an accumulation unit that accumulates the time difference between the detection signal DE and the reference signal OS (the amount of deviation in the detection timing of the detection signal DE relative to the output timing of the reference signal OS).

[0140] When the time difference t is ±1 [ms] (Y in ST22), an electromagnetic brake with an action period of 500 [ms] is applied (ST23), and a speed control pulse with an output period of 4 [ms] is output to the first terminal O1 (ST24).

[0141] If the time difference t is greater than 10 [ms] (Y in ST25), an electromagnetic brake with an action period of 800 [ms] is applied (ST26), and a speed control pulse with an output period of 8 [ms] is output to the first terminal O1 (ST27). In other words, if the rate is significantly advanced, the braking force is increased.

[0142] When the time difference t is greater than 5 [ms] and less than or equal to 10 [ms] (Y in ST28), an electromagnetic brake with an action duration of 800 [ms] is applied (ST29), and a speed control pulse with an output duration of 6 [ms] is output to the first terminal O1 (ST30). In other words, the braking force is slightly less than when the time difference t is greater than 10 [ms].

[0143] When the time difference t is greater than 1 [ms] and 5 [ms] or less (Y in ST31), an electromagnetic brake with an action duration of 800 [ms] is applied (ST32), and a speed control pulse with an output duration of 4 [ms] is output to the first terminal O1 (ST33). In other words, the braking force is slightly less than when the time difference t is greater than 5 [ms] and 10 [ms] or less.

[0144] If the time difference t is -5 [ms] or more and less than -1 [ms] (Y in ST34), an electromagnetic brake with an action duration of 800 [ms] is applied (ST35), and no speed control pulse is output (ST36). In other words, if the rate is lagging, the braking force is reduced.

[0145] If the time difference t is -10 [ms] or more and less than -5 [ms] (Y in ST37), the electromagnetic brake is not applied (ST38), and no speed control pulse is output (ST39). In other words, the braking force is reduced compared to the case where the time difference t is -5 [ms] or more and less than -1 [ms].

[0146] If the time difference t is less than -10 [ms] (ST40), the electromagnetic brake is not applied (ST41), and a speed control pulse with an output period of 4 [ms] is output to the second terminal O1 (ST42). In other words, the braking force is set to 0, and a force is generated in the direction of advancement of the rate.

[0147] [Other examples of braking control] Next, with reference to Figures 21 and 22, the braking control for each state of the mechanical clock 1 will be explained.

[0148] [Other examples of braking control: during power supply circuit startup] Figure 21 is a timing chart showing an example of braking control when a power supply circuit starts up from a stopped state.

[0149] In each embodiment of the first embodiment, an example was described in which the braking force that brakes the permanent magnet 41 is controlled each time the detection signal DE is detected. As described above, when a braking force is generated, the rotational speed of the permanent magnet 41 decreases, and the amount of power generated decreases. Therefore, it is preferable to increase the rotational speed of the permanent magnet 41 to generate power efficiently until sufficient charge is stored in the capacitor C shown in Figure 9.

[0150] Therefore, in the example shown in Figure 21, when the power supply circuit 60 starts up from a stopped state, braking control is not performed even if the detection signal DE is detected during a predetermined period until sufficient charge is stored. For example, braking control may be started after the detection signal DE has been detected a predetermined number of times. More specifically, in order to prevent the power supply circuit 60 from immediately switching to a stopped state after the control starts, the number of times the detection signal DE needs to be detected before braking control can be started (until recovery) should be set to a large value. When the torque of the power spring 11 is strong, the force that rotates the balance wheel 31 is strong, resulting in high power generation, and conversely, when the torque of the power spring 11 is weak, the power generation is low. Therefore, it is desirable to set the number of detections required for recovery based on the low torque of the power spring 11.

[0151] In the example shown in Figure 21, the decrease in power generation during the startup of the power supply circuit 60 can be suppressed. As a result, the time required for the power supply circuit 60 to start up can be shortened.

[0152] [Other braking control examples: Braking control that considers the rotation direction of the balance wheel] Figure 22 is a timing chart showing an example of the output timing of the reference signal. Due to manufacturing variations during the assembly of the mechanical clock 1, or adjustments to the position of the balance wheel 31 by the support member 33 during the shipping inspection, the rotation angle of the balance wheel 31 may differ between the forward and reverse directions. If the rotation angle differs, the timing at which the detection signal DE is detected will differ between the forward and reverse directions. As a result, proper braking control may not be performed.

[0153] For example, when adjusting to a 1000 ms period of the reference signal OS, if the actual swing angle of the balance wheel 31 differs from the design value due to manufacturing variations, a difference in the detection timing of the detection signal DE may occur between the forward and reverse directions. For example, if there is a difference between the forward and reverse directions, such as a 985 ms period in the forward direction and a 1015 ms period in the reverse direction, when the forward and reverse directions are matched, the total period is 2000 ms, and the overall period is not off. However, the circuit identifies a deviation of ±15 ms in both the forward and reverse directions. According to the flowchart in Figure 20, this follows ST25, 26, 27 or ST40, 41, 42, causing the control to switch every cycle and continuously outputting strong speed control pulses. As a result, unnecessary control is performed, leading to increased current consumption.

[0154] Therefore, in the example shown in Figure 22, a configuration was adopted in which the reference signal OS is set using a 2-step (2-second) reference. The upper part of Figure 22 shows an example of the back electromotive force waveform when the detection signal DE detected in the forward and reverse directions are different. The lower part of Figure 22 shows an example of the timing chart when the reference signal OS is set using a 2-step (2-second) reference.

[0155] As shown in the lower part of Figure 22, the output interval of the odd-numbered reference signal OS from the left is defined as tr1, and the output interval of the even-numbered reference signal OS from the left is defined as tr2 (=tr1). This example can be implemented by the control circuit 44 performing two-system control in 2-step units (2-second units). Then, appropriate braking control should be performed when a rate abnormality is detected in either of the control systems. For the sake of simplifying the circuit configuration, it is also possible to use only one control system with an output interval of either tr1 or tr2.

[0156] As shown in the example in Figure 22, by setting the reference signal OS as a two-step reference (tr1 and tr2) and performing braking control according to each, highly accurate braking control becomes possible even if there is a difference in the rotation angle of the balance wheel 31 in the forward and reverse directions. In addition, unnecessary control can be minimized, so current consumption can be reduced.

[0157] [Other examples of braking control: When the torque of the power spring weakens] Next, referring to Figures 23 to 26, we will explain the braking control when the power mainspring 11 is unwound due to continuous use of the mechanical watch 1 and the torque (power) of the power mainspring 11 weakens. Figure 23 is a graph showing the relationship between the rotation angle of the balance wheel and the holding torque acting on the permanent magnet, and the relationship between the rotation angle of the balance wheel and the torque of the hairspring. Figure 24 is a diagram explaining the direction in which the torque and holding torque of the hairspring act. Figure 25 is a timing chart showing an example of braking control when the torque of the power mainspring weakens. Figure 26 is a diagram showing an example of detection of a detection signal when it is determined that the torque of the power mainspring has weakened.

[0158] As shown in Figure 23, the torque T1 of the hairspring 32 is proportional to the rotation angle of the balance wheel 31. The holding torque T2 is the force acting on the permanent magnet 41 due to the magnetic influence of the soft magnetic core 42, and is represented by a sinusoidal curve corresponding to the rotation angle of the balance wheel 31.

[0159] As shown in Figures 23 and 24, for example, when the rotation angle of the balance wheel 31 is 45°, both the torque T1 of the hairspring 32 and the holding torque T2 acting on the permanent magnet 41 are positive. Therefore, the holding torque T2 acts on the permanent magnet 41, increasing its rotation in the positive direction (counterclockwise direction in Figure 24).

[0160] On the other hand, as shown in Figures 23 and 24, for example, if the rotation angle of the balance wheel 31 is 135°, the torque T1 of the hairspring 32 is positive, and the holding torque T2 acting on the permanent magnet 41 is negative. In other words, the holding torque T2 acts in the opposite direction to the torque T1 of the hairspring 32. Therefore, a force that weakens the rotation in the positive direction acts on the permanent magnet 41 due to the holding torque T2.

[0161] Here, as the torque of the power mainspring 11 decreases with the continuous use of the mechanical clock 1, the power supplied to the balance wheel 31 decreases, and the amplitude (rotation angle) of the balance wheel 31 decreases.

[0162] As described above, the holding torque T2 acting on the permanent magnet 41 is represented by a sinusoidal curve, and its sign reverses depending on the rotation angle of the balance wheel 31. For example, as shown in Figure 23, the sign reverses at 90° and 180° rotation angles of the balance wheel 31. When the swing angle fluctuates across this boundary where the sign of the holding torque T2 reverses, the holding torque T2 acts in the opposite direction to the intended direction, resulting in a large deviation in the rate.

[0163] For example, as shown in Figure 23, the holding torque T2 is negative at an amplitude of 120°. When the torque of the power spring 11 decreases, and the amplitude becomes 80° instead of the original 120°, the holding torque T2 becomes positive. As a result, a force acts in the direction of increasing the torque T1 of the hairspring 32, causing the rate to advance. This results in a large deviation in the rate. In this state, even if the braking control of the first embodiment and its modified form is continued, the deviation in the rate will not be resolved.

[0164] Therefore, in this example, when the torque of the power spring 11 weakens, the braking control is switched to perform a different braking control than under normal conditions. Specifically, as shown in Figure 25, when the torque of the power spring 11 weakens, the output of the speed control pulse to the first terminal O1 is stopped, and a speed control pulse is output to the second terminal O2. The timing of the speed control pulse output to the second terminal O2 is preferably while the balance wheel 31 (permanent magnet 41) rotates from 90° to 0° and while it rotates from -90° to 0°.

[0165] Outputting a speed control pulse to the second terminal O2 increases the swing angle of the balance wheel 31. As a result, in the example above, the swing angle returns from 80° to 120°, the swing angle before it decreased, allowing the permanent magnet 41 to be subjected to the appropriate holding torque T2. Consequently, deviations in the rate caused by a weakening of the torque of the power mainspring 11 can be suppressed.

[0166] Furthermore, whether or not the torque of the power spring 11 is weakening can be determined based on the waveform of the detected back electromotive force. For example, the control circuit 44 can determine that the power spring 11 is weakening if the timing of the detection signal DE differs from the timing of the output of the reference signal OS a predetermined number of times or more. In other words, if the rate deviation persists for a predetermined period of time under normal control, it can be determined that the torque of the power spring 11 is weakening. In this case, the rate adjustment means 40 can have a counter that counts the number of times the deviation has occurred. Figure 25 shows an example where the control switches to increasing the amplitude when the deviation occurs 10 or more times.

[0167] Furthermore, the control circuit 44 may determine whether the torque of the power spring 11 is weakening based on the detected peak of the back electromotive force. Specifically, the control circuit 44 may determine that the torque of the power spring 11 is weakening if a back electromotive force of Vth1 or higher is not detected for a predetermined period of time. If the condition in which a back electromotive force of Vth1 or higher is not detected continues for a predetermined period of time, the control circuit 44 may detect a detection signal DE based on a threshold Vth2 (second threshold) that is smaller than the threshold Vth1, as shown in Figure 26. Then, based on the detection timing of the detection signal DE with respect to the threshold Vth2, control may be performed to output a speed control pulse to the second terminal O2 as shown in Figure 25.

[0168] In Figure 25, an example is shown in which a speed control pulse is output to the second terminal O2 when it is determined that the torque of the power spring 11 is weakening, but this is not the only example. For example, control to weaken the braking force may be performed by shortening the output period of the speed control pulse and outputting it to the first terminal O1, stopping the output of the speed control pulse to the first terminal O1, or stopping the action of the electromagnetic brake. In this case, multiple threshold values ​​Vth2 shown in Figure 26 may be set, and the control of the braking force may be switched in stages according to the magnitude of the peak of the back electromotive force.

[0169] Furthermore, as shown in Figure 27, if the detection signal is not detected due to a weakening of the torque of the power spring 11, the control pulse may be output based on the reference signal OS. Figure 27 shows an example in which, even if the detection signal is not detected, the electromagnetic brake is applied when time tb1 has elapsed since the reference signal OS was output, and a control pulse is output to the first terminal O1 when time tp1 (>tb1) has elapsed since the reference signal OS was output. In this example as well, the determination of whether or not the torque of the power spring 11 is weakening should be made based on the waveform of the detected back electromotive force. If the control circuit 44 determines that the torque of the power spring 11 is weakening, it should switch to the braking control shown in Figure 27, which outputs a control pulse based on the reference signal OS.

[0170] As shown in the example in Figure 27, even if a detection signal is not detected due to a weakening of the torque of the power mainspring 11, a braking force can be generated, suppressing the balance wheel 31 from performing high-frequency vibrations. As a result, it is possible to prevent a user who observes the movement of the mechanical watch 1 from mistakenly believing that the mechanical watch 1 is malfunctioning.

[0171] [Other braking control examples: Detection of negative back electromotive force] Next, with reference to Figures 28 and 29, braking control that improves the detection accuracy of rotation detection will be described. In each embodiment of the first embodiment described above, an example was described in which rotation detection was performed based on whether or not the back electromotive force was greater than or equal to a predetermined threshold Vth (>+0.5). In this example, an example is described in which the detection accuracy of rotation detection is improved by performing rotation detection based on a negative back electromotive force in addition to a positive back electromotive force.

[0172] Specifically, in addition to determining whether the back EMF is greater than or equal to the threshold +Vth, it is also determined whether the back EMF is less than or equal to -Vth. In the example shown in Figure 28, the positive threshold +Vth was set to +0.5[V] and the negative threshold -Vth was set to -0.25[V]. The reason why the absolute value of the negative threshold -Vth is smaller than the absolute value of the positive threshold +Vth is that, as will be explained later, the absolute value of the peak of the negative back EMF is smaller than the absolute value of the peak of the positive back EMF. However, this is just one example, and the threshold values ​​are not limited to these.

[0173] In this example, the signal detected by the rotation detection circuit 45 when a back electromotive force of +0.5[V] or greater (positive threshold +Vth) is generated is defined as the detection signal +DE. Furthermore, the signal detected by the rotation detection circuit 45 when a back electromotive force of -0.25[V] or less (negative threshold -Vth) is generated is defined as the detection signal -DE.

[0174] The waveform of the back electromotive force in this example is the same as that shown in the lower part of Figure 6 above. That is, in this example as well, the angular velocity of the permanent magnet 41 is at its maximum while the permanent magnet 41 rotates from a rotation angle of 0° to 180°, and the positive back electromotive force generated in the coil 43 is at its peak. Also, at a rotation angle of 180°, which is the position of magnetic equilibrium for the permanent magnet 41, the back electromotive force generated in the coil 43 is zero. Furthermore, a negative back electromotive force 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 it moves from a rotation angle of 0° to 180°. Therefore, the absolute value of the peak of the negative back electromotive force is smaller than the absolute value of the peak of the positive back electromotive force.

[0175] Similarly, as the permanent magnet 41 rotates from a rotation angle of 0° to -180°, the angular velocity of the permanent magnet 41 is at its maximum, and the positive back electromotive force generated in the coil 43 peaks. Also, at the rotation angle of -180°, which is the position of magnetic equilibrium for the permanent magnet 41, the back electromotive force generated in the coil 43 is zero. Furthermore, as the permanent magnet 41 rotates from a rotation angle of -180° to -340°, a negative back electromotive force is generated in the coil 43. The angular velocity of the permanent magnet 41 at this time is smaller than the angular velocity when it moves from a rotation angle of 0° to -180°. Therefore, the absolute value of the peak of the negative back electromotive force will be smaller than the absolute value of the peak of the positive back electromotive force.

[0176] As the waveform of the back electromotive force generated in this example is as described above, as shown in Figure 28, a peak of positive back electromotive force appears followed by a peak of negative back electromotive force.

[0177] In the example shown in Figure 28, the timing at which the negative detection signal -DE is detected is compared with the output timing of the reference signal, and braking control is performed based on the result of this comparison. Specifically, if the difference between the detection timing of the negative detection signal -DE and the output timing of the reference signal OS is within a predetermined range, the electromagnetic brake is applied at a time tb1 elapsed after the negative detection signal -DE is detected, and a speed control pulse is output to the first terminal O1 at a time tp1 (>tb1) elapsed after the negative detection signal -DE is detected.

[0178] In this example, for instance, if a positive detection signal +DE is detected and a negative detection signal -DE is not detected, the detection timing of the positive detection signal +DE is compared with the output timing of the reference signal OS, and braking control is performed based on the comparison result. By adopting a configuration in which two criteria are provided for rotation detection, false detections caused by momentary noise can be suppressed. As a result, highly accurate braking control becomes possible.

[0179] Figure 29 is a circuit diagram for realizing the braking control shown in Figure 28. In order to detect a negative back EMF as in this example, it is best to connect the rotation detection circuit 45 to the second terminal O2 as well as the first terminal O1, as shown in Figure 29. When a positive back EMF is detected, transistor TP1 should be turned OFF and transistor TP2 should be turned ON. On the other hand, when a negative back EMF is detected, transistor TP1 should be turned ON and transistor TP2 should be turned OFF.

[0180] [Other brake control examples: Other variations of brake control when a rate deviation occurs] Next, with reference to Figures 30 and 31, other modifications of braking control in the event of a rate deviation will be described. Figures 30 and 31 are timing charts showing an example of braking control in another modification of the first embodiment. Figures 30 and 31 describe an example of braking control performed according to the degree of rate deviation. Specifically, an example in which the magnitude of the braking force is varied according to the degree of rate deviation will be described. In this modification, the magnitude of the braking force is determined by the duty cycle of the regulating pulse output by the regulating pulse output circuit 46 and the duty cycle of the electromagnetic brake DB actuated by the braking circuit 80.

[0181] In this modified example, the control circuit 44 selects the speed control pulse and the braking rank of the electromagnetic brake based on the detection timing of the detection signal DE. The braking rank is a rank corresponding to the duty cycle. In this modified example, the duty cycle is the ratio of the output period during which the speed control pulse is output in a predetermined section, and the ratio of the operation period during which the electromagnetic brake is applied in a predetermined section. For example, duty cycles of 0%, 25%, 50%, 75%, and 100% may be preset.

[0182] In this modified example, the control circuit 44 controls the braking force generated in a preset braking section tc, which occurs after the detection signal DE is detected. That is, a braking section tc in which a speed control pulse is output or the electromagnetic brake is applied is preset, and braking control is performed by making the energization time within the braking section tc variable. In this modified example, as shown in Figure 30, the start of the braking section tc is set to the timing after time tp has elapsed since the detection signal DE was detected.

[0183] In the example shown in Figure 30, the electromagnetic brake is applied during the period when no speed control pulse is output in the braking section tc. For example, if the duty cycle of the speed control pulse is 50%, an electromagnetic brake with a 50% duty cycle is applied.

[0184] In this modified example, a braking rank corresponding to the braking force is set. Specifically, the rank in which the speed control pulse output to the first terminal O1 has a duty cycle of 100% and the electromagnetic brake has a duty cycle of 0% is defined as braking rank "0000". The rank in which the speed control pulse output to the first terminal O1 has a duty cycle of 75% and the electromagnetic brake has a duty cycle of 25% is defined as braking rank "0001". The rank in which the speed control pulse output to the first terminal O1 has a duty cycle of 50% and the electromagnetic brake has a duty cycle of 50% is defined as braking rank "0010". The rank in which the speed control pulse output to the first terminal O1 has a duty cycle of 25% and the electromagnetic brake has a duty cycle of 75% is defined as braking rank "0011". The rank in which the speed control pulse output to the first terminal O1 has a duty cycle of 0% and the electromagnetic brake has a duty cycle of 100% is defined as braking rank "0100". When these braking ranks are arranged in order of decreasing braking force, they are "0000", "0001", "0010", "0011", and "0100".

[0185] In the example shown in Figure 30, if there is no delay or advance in the rate, the control circuit 44 selects braking rank "0010". That is, the duty cycle of the speed control pulse output to the first terminal O1 is set to 50%, and the duty cycle of the electromagnetic brake is set to 50%.

[0186] Furthermore, the greater the rate of progress, the higher the braking rank. In Figure 30, when the detection timing of the detection signal DE is 2t ahead of the reference signal OS, the control circuit 44 selects braking rank "0000". Also, when the detection timing of the detection signal DE is t ahead of the reference signal OS, the control circuit 44 selects braking rank "0001".

[0187] Furthermore, the greater the delay in the rate of motion, the lower the braking rank. In Figure 30, when the detection timing of the detection signal DE is delayed by time t compared to the reference signal OS, the control circuit 44 selects braking rank "0011". Also, when the detection timing of the detection signal DE is delayed by time 2t compared to the reference signal OS, the control circuit 44 selects braking rank "0100".

[0188] Figure 31 shows examples of cases where a large delay occurs. Specifically, it shows examples where the detection timing of the detection signal DE is delayed by 3t, 4t, 5t, 6t, 7t, and 8t compared to the reference signal OS.

[0189] In this example, if the detection timing of the output signal DE is delayed by 3t or more compared to the reference signal OS, no speed control pulse is output to the first terminal O1. That is, the duty cycle of the speed control pulse output to the first terminal O1 is set to 0%. Then, as the delay increases, the duty cycle of the electromagnetic brake is reduced. If the delay increases further, the electromagnetic brake is not applied, and a speed control pulse is output to the second terminal O2. Also, as the delay increases, the duty cycle of the output to the second terminal O2 is increased.

[0190] In the example shown in Figure 31, the braking rank "0101" is defined as the rank where the speed control pulse output to the first terminal O1 has a duty cycle of 0% and the electromagnetic brake has a duty cycle of 75%. The braking rank "0110" is defined as the rank where the speed control pulse output to the first terminal O1 has a duty cycle of 0% and the electromagnetic brake has a duty cycle of 50%. The braking rank "0111" is defined as the rank where the speed control pulse output to the first terminal O1 has a duty cycle of 0% and the electromagnetic brake has a duty cycle of 25%. The braking rank "1000" is defined as the rank where both the speed control pulse and the electromagnetic brake output to the first terminal O1 have a duty cycle of 0%. The braking rank "1001" is defined as the rank where the speed control pulse output to the second terminal O2 has a duty cycle of 25% and the electromagnetic brake has a duty cycle of 0%. The braking rank "1010" is defined as the rank where the speed control pulse output to the second terminal O2 has a duty cycle of 50% and the electromagnetic brake has a duty cycle of 0%. When these braking ranks are arranged in order of decreasing braking force, they are "0101", "0110", "0111", "1000", "1001", and "1010".

[0191] In the example shown in Figure 31, the greater the delay in the rate of motion, the lower the braking rank. In Figure 31, when the detection timing of the detection signal DE is delayed by 3t time from the reference signal OS, the control circuit 44 selects braking rank "0101". Also, when the detection timing of the detection signal DE is delayed by 4t time from the reference signal OS, the control circuit 44 selects braking rank "0101". Also, when the detection timing of the detection signal DE is delayed by 5t time from the reference signal OS, the control circuit 44 selects braking rank "0111". Also, when the detection timing of the detection signal DE is delayed by 6t time from the reference signal OS, the control circuit 44 selects braking rank "1000". Also, when the detection timing of the detection signal DE is delayed by 7t time from the reference signal OS, the control circuit 44 selects braking rank "1001". Also, when the detection timing of the detection signal DE is delayed by 8t time from the reference signal OS, the control circuit 44 selects braking rank "1010".

[0192] [Flowchart of braking control in other modifications of the first embodiment] Figure 32 is a flowchart showing an example of braking control in another modification of the first embodiment. The same reference numerals are used for the same steps as shown in Figure 20, and their descriptions are omitted. The braking rank is the same as that described with reference to Figures 30 and 31.

[0193] Figures 30 and 31 above show an example of braking control performed according to the difference in detection timing of the detection signal DE relative to the output timing of the reference signal OS. However, the amount of the difference may be accumulated, and braking control may be performed according to the accumulated amount of the difference. The flow of braking control according to the accumulated amount of the difference will be described below. Although not shown in the figures, it is preferable that the rate adjustment means 40 has a counter that accumulates the time difference between the detection signal DE and the reference signal OS (the amount of difference in detection timing of the detection signal DE relative to the output timing of the reference signal OS).

[0194] In the example shown in Figure 32, if the time difference t is within ±1 [ms] (Y in ST251), the control circuit 44 selects braking rank "0010" (ST261). If the time difference t is greater than 5 [ms] (Y in ST252), the control circuit 44 selects braking rank "0000" (> braking rank "0010") (ST262). If the time difference t is greater than 1 [ms] and 5 [ms] or less (Y in ST253), the control circuit 44 selects braking rank "0001" (> braking rank "0010") (ST263).

[0195] If the time difference t is -5[ms] or more and -1[ms] or less (Y in ST254), the control circuit 44 selects braking rank "0011" (<"0001") (ST264). If the time difference t is -10[ms] or more and less than -5[ms] (Y in ST255), the control circuit 44 selects braking rank "0100" (<braking rank "0011") (ST265). If the time difference t is -15[ms] or more and less than -10[ms] (Y in ST256), the control circuit 44 selects braking rank "0101" (<braking rank "0100") (ST266). If the time difference t is less than -15[ms] (Y in ST257), the control circuit 44 selects braking rank "0110" (<braking rank "0101") (ST267).

[0196] In the other modified examples described above, the duty cycle of the speed control pulse output to the first terminal O1, the duty cycle of the speed control pulse output to the second terminal O2, and the duty cycle of the electromagnetic brake DB are associated with a preset braking rank, making it easy to handle the braking force in the circuit. In other words, it is easy to control the braking force by the control circuit 44.

[0197] [Second Embodiment] Next, a second embodiment will be described with reference to Figures 33 to 35. Figures 33 and 34 show an example of braking control in the second embodiment.

[0198] Here, during the period when the electromagnetic brake DB is in operation, no back electromotive force is detected because coil 43 is short-circuited. That is, during the operating period b1 of the electromagnetic brake DB shown in the lower part of Figure 33, the back electromotive force is 0 [V]. The dashed lines in the waveforms in the upper part of Figure 33 show waveforms that may be detected when the electromagnetic brake DB is not in operation, and the solid lines in the waveforms in the upper part of Figure 33 show the detected waveforms. Similarly, in Figures 10 to 15, 21, 22, 25, 28, and Figures 36 to 37C described later, no back electromotive force is detected during the period when the electromagnetic brake DB is in operation, but for the sake of visibility, all waveforms of the back electromotive force are shown as solid lines.

[0199] In the second embodiment, an example is described in which braking force is controlled by applying an electromagnetic brake, rather than by outputting a speed control pulse. The physical configuration in the second embodiment may be the same as that of the first embodiment described with reference to Figures 1 to 5, but the rate adjustment means 40 does not necessarily have a speed control pulse output circuit 46.

[0200] While braking using an electromagnetic brake has the advantage of lower power consumption compared to braking using a speed control pulse output, it may result in insufficient braking force to achieve a low speed for the balance wheel 31. Therefore, in the second embodiment, a configuration is adopted that generates enough braking force to achieve a low speed for the balance wheel 31 by extending the operating period of the electromagnetic brake compared to the first embodiment. Furthermore, in the second embodiment, a configuration is adopted in which the operating period of the electromagnetic brake is variable according to the advance or delay of the detection timing of the detection signal DE. For example, the operating period of the electromagnetic brake when the detection timing of the detection signal DE is advanced is made longer than the operating period of the electromagnetic brake when the detection timing of the detection signal DE is delayed.

[0201] The second embodiment is similar to the second embodiment of the first embodiment described with reference to Figure 10 in that it controls the braking force solely by applying an electromagnetic brake. The second embodiment differs from the second embodiment of the first embodiment in that it includes control to apply the electromagnetic brake based on a two-step (two-second) timeframe.

[0202] Figure 33 shows an example where the reference signal OS is set to a 2-step (2-second) interval. As a result, the detection signal DE is detected every 2 steps, and the electromagnetic brake DB is activated every 2 steps. In the following explanation, the mode in which the electromagnetic brake DB is activated every 1 step (1 second) is called the first braking mode, and the mode in which the electromagnetic brake DB is activated every 2 steps (2 seconds) is called the second braking mode. In the first braking mode, it is desirable that the reference signal OS is output at 1-second intervals (first interval), and that the duration of operation of the electromagnetic brake DB is shorter than the first interval. In the second braking mode, it is desirable that the reference signal OS is output at 2-second intervals (second interval), and that the duration of operation of the electromagnetic brake DB is shorter than the second interval.

[0203] In the second embodiment, as shown in the lower part of Figure 33, the control includes applying an electromagnetic brake DB with an operating period b1 that is longer than 1 second but shorter than 2 seconds, at a time tb1 that has elapsed since the detection signal DE was detected.

[0204] In the second embodiment, the control circuit 44 switches the braking mode based on the detection timing of the detection signal DE. In the second embodiment, the control circuit 44 also selects the braking rank of the electromagnetic brake based on the detection timing of the detection signal DE. The braking rank is a rank corresponding to the duty cycle. In the second embodiment, the duty cycle is the percentage of the operating period during which the electromagnetic brake is applied in a predetermined section.

[0205] Figure 34(a) shows an example of the timing and duration of operation of the electromagnetic brake in the first braking mode, and Figure 34(b) shows an example of the duration of operation of the electromagnetic brake in the second braking mode.

[0206] In the first braking mode of the second embodiment, if the period of the preset braking section tc after the detection signal DE is detected is set to 100%, then the rank in which the electromagnetic brake operation period is 25% is defined as braking rank "10011". Similarly, the ranks in which the electromagnetic brake operation period is 50% and 75% are defined as braking ranks "10010" and "10001", respectively.

[0207] Furthermore, in the second braking mode of the second embodiment, if the period of the preset braking section tc2 (>tc1) after the detection signal DE is detected is set to 100%, the rank in which the electromagnetic brake operation period is 65% is designated as braking rank "11011". Similarly, the ranks in which the electromagnetic brake operation period is 75% and 85% are designated as braking ranks "11010" and "11001", respectively.

[0208] Furthermore, the duration of the electromagnetic brake's action in each braking rank of the second braking mode should be longer than the duration of the electromagnetic brake's action in each braking rank of the first braking mode. In other words, the braking force of the electromagnetic brake in each braking rank of the second braking mode should be greater than the braking force of the electromagnetic brake in each braking rank of the first braking mode.

[0209] Furthermore, the duration of the electromagnetic brake's operation in each braking rank of the second braking mode should be longer than the output interval (first interval) of the reference signal OS in the first braking mode. This allows for a greater braking force in the second braking mode. Also, the duration of the electromagnetic brake's operation in each braking rank of the second braking mode should be shorter than two steps (2 seconds) of the reference signal OS.

[0210] Furthermore, the duration of the electromagnetic brake's operation in each braking rank of the first braking mode should be shorter than the interval at which the reference signal OS is output. This allows the detection signal DE to be detected every second and the power generation to be maintained in the first braking mode.

[0211] Furthermore, in the second embodiment, the braking circuit 80 is preferably configured to generate multiple braking forces with different durations of action in each of the first and second braking modes.

[0212] Figure 34(a) shows an example where the control circuit 44 selects braking rank "10001" (electromagnetic brake for the second operating period) when there is an advance in the rate, selects braking rank "10010" (electromagnetic brake for the first operating period) when there is neither an advance nor a lag in the rate, and selects braking rank "10011" (electromagnetic brake for the third operating period) when there is a lag in the rate. In other words, the more the rate is advanced, the greater the braking force is relatively increased.

[0213] Figure 34(b) shows an example where the control circuit 44 selects braking rank "11001" (electromagnetic brake for the second operating period) when there is an advance in the rate, selects braking rank "11010" (electromagnetic brake for the first operating period) when there is neither an advance nor a lag in the rate, and selects braking rank "11011" (electromagnetic brake for the third operating period) when there is a lag in the rate. In other words, the more the rate is advanced, the greater the braking force is relatively increased.

[0214] In Figure 34(b), the output period of the reference signal OS, which does not contribute to the control of the braking force, is shown as the output period tts. In the second braking mode, the output timing of the reference signal OS itself may be set to 2 steps (2 seconds). That is, the reference signal OS, indicated by the output period tts, does not need to be output. In this case, it is preferable to generate a reference signal OS that is output approximately every 2000 [ms] by dividing the oscillation signal based on the crystal oscillator 70.

[0215] [Flowchart of braking control in the second embodiment] Figure 35 is a flowchart showing an example of braking control in the second embodiment. The braking rank is the same as that described with reference to Figure 34.

[0216] In the second embodiment, after the power supply circuit 60 is started by generating electricity through the motion of the permanent magnet 41 (Y in ST1), braking control is initiated. Then, after a back electromotive force of Vth or higher is generated, that is, after the detection signal DE is detected by the rotation detection circuit 45 (Y in ST2), the time difference between the detection signal DE and the reference signal OS (the amount of deviation in the detection timing of the detection signal DE relative to the output timing of the reference signal OS) is obtained (ST50).

[0217] Furthermore, the control circuit 44 determines the current braking mode (ST51). If the current braking mode is the first braking mode (Y in ST51), the following control is performed.

[0218] If the time difference t is within ±1 [ms] (Y in ST511), the control circuit 44 selects braking rank "10010" (ST512). If the time difference t is greater than 1 [ms] and 5 [ms] or less (Y in ST513), the control circuit 44 selects braking rank "10001" (> braking rank "10010") (ST514).

[0219] If the time difference t is less than -1 (Y in ST515), the control circuit 44 selects braking rank "10011" (< braking rank "10010") (ST516). If the time difference t is greater than 5 [ms] (Y in ST517), the control circuit 44 selects braking rank "10001" (ST518).

[0220] Furthermore, if the time difference t is greater than 5 [ms] (Y in ST517), that is, if the detection signal DE is significantly ahead, the braking mode is switched from the first braking mode to the second braking mode (ST519). In other words, the braking mode is switched to increase the braking force. By increasing the braking force in this way, the low speed of the balance wheel 31 can be maintained.

[0221] On the other hand, if the current braking mode is the second braking mode (ST51 N), the following control is performed.

[0222] If the time difference t is within ±1 [ms] (Y in ST521), the control circuit 44 selects braking rank "11010" (ST522). If the time difference t is -5 [ms] or more and less than 1 [ms] (Y in ST523), the control circuit 44 selects braking rank "11011" (< braking rank "10010") (ST524).

[0223] If the time difference t is greater than 1 (Y in ST525), the control circuit 44 selects braking rank "11001" (> braking rank "10010") (ST526). If the time difference t is less than -5 [ms] (Y in ST527), the control circuit 44 selects braking rank "11011" (ST528).

[0224] Furthermore, if the time difference t is less than -5 [ms] (Y in ST527), that is, if the detection timing is significantly delayed, the braking mode is switched from the second braking mode to the first braking mode (ST529). In other words, the braking mode is switched to reduce the braking force. By reducing the braking force in this way, excessive braking force can be suppressed and the rate accuracy can be maintained.

[0225] In the second embodiment described above, the operating period of the electromagnetic brake DB can be extended to reduce the speed of the balance wheel 31. Furthermore, the longer operating period of the electromagnetic brake DB can suppress false detection of the detection signal DE.

[0226] In the second embodiment, an example was described in which the braking mode is switched according to the time difference between the detection signal DE and the reference signal OS (the amount of deviation in the detection timing of the detection signal DE relative to the output timing of the reference signal OS), but the invention is not limited to this. For example, a temperature sensor may be provided in the mechanical clock 1, and the braking mode may be switched based on the output of the temperature sensor. For example, if the temperature detected by the temperature sensor exceeds a predetermined value, the braking mode may be switched to the second braking mode. This is because as the temperature rises, the resistance of the coil 43 increases, making the electromagnetic brake DB less effective. When the electromagnetic brake DB becomes less effective due to rising temperature, the rate accuracy can be maintained by executing the second braking mode, which has a longer operating period for the electromagnetic brake DB.

[0227] In the second embodiment, an example was described in which the first braking mode and the second braking mode can be switched, but the system is not limited to this, and a configuration that only performs the second braking mode is also possible. That is, the control circuit 44 may control the braking circuit 80 to always apply the electromagnetic brake DB every two steps (2 seconds). In this case, the period during which the electromagnetic brake DB is applied is preferably the period after the rotational speed of the balance wheel 31 in one direction of rotation reaches its maximum value, and then includes the timing when the rotational speed of the balance wheel 31 in the opposite direction of rotation reaches its maximum value. In addition, in the second embodiment, an example was shown in which the detection signal DE is detected every two steps and the electromagnetic brake DB is applied every two steps, but if the braking force is insufficient, the period during which the electromagnetic brake DB is applied may be extended to every three steps (3 seconds), every four steps (4 seconds), etc., rather than every two steps (2 seconds), and the number of steps in which the detection signal DE is detected may be changed.

[0228] Furthermore, in the second embodiment, as described with reference to Figure 20, a counter, which is an accumulation unit, is provided to accumulate the amount of deviation between the output timing of the reference signal OS and the detection timing of the detection signal DE, and the control circuit 44 may be configured to control the braking force according to the accumulated amount of deviation.

[0229] Furthermore, in the second embodiment, an example was shown in which the duty cycle of the electromagnetic brake is variable between 25% and 85% depending on the amount of deviation in the detection timing of the detection signal DE relative to the output timing of the reference signal OS, but the duty cycle is not limited to this. Also, the system may be configured to allow selection of a braking force where the duty cycle of the electromagnetic brake is 0%. That is, for example, if the detection timing of the detection signal DE is significantly delayed, the electromagnetic brake DB may not be activated.

[0230] [Third Embodiment] Next, a third embodiment will be described with reference to Figure 36. Figure 36 is a diagram illustrating an example of braking control in the third embodiment.

[0231] In the third embodiment, the threshold Vth of the back electromotive force V at which the detection signal DE is detected is set low. Figure 36 shows an example where the threshold Vth is slightly higher than 0[V]. By setting the threshold Vth low in this way, the detection signal DE can be detected even when the power of the power spring 11 weakens over time, and the accuracy of the rate can be maintained.

[0232] However, if the threshold Vth is set low, the detection signal DE may be detected at rotation angles other than the rotation angle at which the rotation speed of the balance wheel 31 reaches its maximum. In other words, there is a possibility of false detection of the detection signal DE. In particular, as shown in Figure 6, the second largest peak in the back electromotive force V occurs after the rotation angle of the balance wheel 31 reaches its maximum, and there is a possibility of false detection of the detection signal DE in accordance with this peak.

[0233] On the other hand, during the period when the electromagnetic brake DB is activated by short-circuiting the first terminal O1 and the second terminal O2, the back electromotive force V is not detected in the first place, and therefore the detection signal DE is not detected. For this reason, it is preferable to suppress false detection of the detection signal DE during the period when the electromagnetic brake DB is not activated.

[0234] Therefore, in the third embodiment, a non-detection period DE_off is provided in which the detection signal DE is not detected regardless of the waveform of the back electromotive force V generated in the coil 43. The non-detection period DE_off is a period in which the detection signal DE is not detected, regardless of whether the back electromotive force V is greater than or equal to a threshold Vth. The non-detection period DE_off is preferably started after a predetermined period has elapsed since the detection of the detection signal DE. That is, it is preferably started after a predetermined period has elapsed since the maximum value of the peak of the waveform of the back electromotive force V occurred. Furthermore, the non-detection period DE_off is preferably a period in which, in the forward and reverse rotational motion of the balance wheel 31, the rotational speed of the balance wheel 31 has reached its maximum value, and before the rotational speed of the balance wheel 31 reaches its maximum value again. That is, the non-detection period DE_off is preferably a period that does not overlap with the timing in which the maximum value of the peak of the back electromotive force V is detected. This makes it possible to maintain the amount of power generated.

[0235] Furthermore, the non-detection period DE_off and the operating period of the electromagnetic brake DB should start at the same time. Also, the non-detection period DE_off should be longer than at least one of the operating periods of the electromagnetic brake DB. In other words, the end point of the non-detection period DE_off should be after the end point of one of the operating periods of the electromagnetic brake DB.

[0236] Figure 36 shows an example in which electromagnetic brakes DB with different operating periods are activated. In Figure 36, the electromagnetic brake DB with the longest operating period is activated after the first detection signal DE is detected, the electromagnetic brake DB with the second longest operating period is activated after the second detection signal DE is detected, and the electromagnetic brake DB with the shortest operating period is activated after the third detection signal DE is detected.

[0237] Furthermore, Figure 36 shows an example where the non-detection period DE_off is longer than the electromagnetic brake DB which acts after the third detection signal DE is detected. Thus, in the third embodiment, it is preferable that the non-detection period DE_off is longer than at least one of the operating periods of the electromagnetic brake DB. This makes it possible to suppress false detection of the detection signal DE after the operating period of the electromagnetic brake DB has elapsed, even when the threshold Vth is set low. As a result, rate accuracy can be maintained.

[0238] In Figure 36, an example is shown where the non-detection period DE_off is always constant, but this is not the only example; it may be variable depending on the operating period of the electromagnetic brake DB. Specifically, for example, the shorter the operating period of the electromagnetic brake DB, the longer the non-detection period DE_off should be. This makes it possible to suppress false detection of the detection signal DE with greater accuracy.

[0239] [Variations in the duration of electromagnetic brake operation] Here, with reference to Figures 37A to 37C, examples of variations in the operating period of the electromagnetic brake will be explained. Figure 37A shows an example in which the operating period of the electromagnetic brake is varied by fixing either the start or end point. Figure 37B shows an example in which the operating period of the electromagnetic brake is varied based on a predetermined reference timing. Figure 37C shows an example in which the operating period of the electromagnetic brake is varied according to the rank level. Note that Figures 37A and 37B show examples in which the braking rank can be switched between ranks 1 to 3, and Figure 37C shows an example in which the braking rank can be switched between ranks 1 to 5. Furthermore, a higher number in these braking ranks indicates a higher duty cycle.

[0240] Figure 34 and other figures above illustrate an example where the end point of the electromagnetic brake DB's operating period is fixed to the end point of the braking section tc, and the start point of the electromagnetic brake's operating period is varied to set the electromagnetic brake period according to the duty cycle. This example corresponds to the example in the upper part of Figure 37A where the braking rank is switched between ranks 1 to 3. However, the variation in the electromagnetic brake's operating period is not limited to this.

[0241] For example, the duration of the electromagnetic brake's operation can be varied, as shown in the lower part of Figure 37A. That is, the starting point of the electromagnetic brake DB's operation can be fixed to the starting point of the braking period tc, while the ending point of the electromagnetic brake can be varied.

[0242] Furthermore, as shown in Figure 37B, the start and end points of the action period may not be fixed, and the action period may be varied based on a predetermined reference timing. Specifically, the periods before and after the predetermined reference timing may be varied according to the rank. Figure 37B shows an example in which the action period is increased by the same length before and after the predetermined reference timing each time the rank increases.

[0243] Furthermore, as shown in Figure 37C, it may be possible to switch between varying the start and end points of the action period depending on the magnitude of the braking rank. In the example shown in Figure 37C, the control circuit 44 fixes the timing of the start point and controls the timing of the end point for multiple action periods included in the first action period group (action periods of ranks 1 to 3). The control circuit 44 also controls the timing of the start point and fixes the timing of the end point for multiple action periods included in the second action period group (ranks 4 to 5). Note that each of the multiple action periods included in the second action period group is longer than the multiple action periods included in the first action period group.

[0244] Thus, until the end of the action period coincides with the end of the braking section tc, it is advisable to delay the end of the action period as the rank increases. After the end of the action period coincides with the end of the braking section tc, it is advisable to advance the start of the action period as the rank increases.

[0245] Furthermore, as shown in Figure 37C, the starting timing of the multiple operating periods (operating periods of rank 1 to 3) included in the first operating period group is a predetermined reference timing after the start of the braking section tc. Also, the ending timing of the multiple operating periods (operating periods of rank 1 to 3) included in the first operating period group is before the end of the braking section tc. Furthermore, the starting timing of the multiple operating periods (operating periods of rank 4 to 5) included in the second operating period group is before the reference timing, and the ending timing of the multiple operating periods (operating periods of rank 4 to 5) included in the second operating period group is the timing of the end of the braking section tc. In the example shown in Figure 37C, the reference timing is the timing after the rotational speed of the balance wheel 31 reaches its maximum value in both the forward and reverse rotational motion of the balance wheel 31, and before the next peak in the waveform of the back electromotive force (the negative peak in the waveform shown in Figure 37C) occurs.

[0246] Thus, for lower ranks, the start of the action period should be set to after the timing when the maximum value of the back EMF is detected, while for higher ranks, the start of the action period should be set so that it coincides with the timing when the maximum value of the back EMF is detected. Note that the timing when the maximum value of the back EMF is detected is the peak of power generation. As shown in Figure 37C, by setting the start or end of the action period, the braking force can be adjusted in the low power generation region for lower ranks, and the braking force can be adjusted in the high power generation region where a higher braking force is required for higher ranks. As a result, it becomes possible to achieve both power generation and braking.

[0247] [Rank Switching] Next, an example of rank switching will be explained with reference to Figure 38. Figure 38 is a flowchart illustrating an example of rank switching. Figure 38 shows an example in which the rank is changed according to the accumulated time difference t when an electromagnetic brake of the same rank is applied consecutively a predetermined number of times. Specifically, it shows an example in which the rank is increased by one if the accumulated time difference t is 0 or positive, and the rank is decreased by one if the accumulated time difference t is negative.

[0248] After the power supply circuit 60 is activated by power generation due to the movement of the permanent magnet 41 (Y in ST1), braking control is started. Then, after a reverse electromotive force equal to or higher than a predetermined threshold value Vth is generated, that is, after the detection signal DE is detected by the rotation detection circuit 45 (Y in ST2), the period difference between the detection signal DE and the reference signal OS is calculated, and the period difference t is accumulated (ST60).

[0249] If the number of times of continuously performing braking control at the same rank is less than 4 (N in ST61), braking control according to the current braking rank is performed (ST62).

[0250] If the number of times of continuously performing braking control at the same rank has reached 4 (Y in ST61) and the accumulated period difference t is 0 or more (Y in ST63), after raising the braking rank by 1 (ST64), braking control according to the raised braking rank is performed (ST62).

[0251] If the number of times of continuously performing braking control at the same rank has reached 4 (Y in ST61) and the accumulated period difference t is less than 0 (N in ST63), after lowering the braking rank by 1 (ST65), braking control according to the lowered braking rank is performed (ST65).

[0252] Furthermore, referring to FIG. 39, a modification example of the rank switching shown in FIG. 38 will be described. FIG. 39 is a flowchart showing a modification example of the rank switching shown in FIG. 38. In FIG. 39, an example in which the rank is greatly changed when the accumulated period difference t is large and the electromagnetic brake of the same rank is continuously operated a predetermined number of times is shown. Specifically, an example in which the rank is raised or lowered by 2 when the accumulated period difference t is greater than ±30 [ms] is shown.

[0253] After the power supply circuit 60 is activated by power generation due to the movement of the permanent magnet 41 (Y of ST1), braking control is started. Then, after a back electromotive voltage of a predetermined threshold value Vth or more is generated, that is, after a detection signal DE is detected by the rotation detection circuit 45 (Y of ST2), the period difference between the detection signal DE and the reference signal OS is calculated, and the period difference t is accumulated (ST70).

[0254] When the accumulated period difference t is 30 [ms] or less and -30 [ms] or more (N of ST71), it is determined whether braking control at the same rank has been continuously performed four or more times (ST72). When it is determined that the number of times of continuously performing braking control at the same rank is four or more (Y of ST72), and when the accumulated period difference t is 0 or more (Y of ST74), the rank is raised by one (ST75). Then, braking control corresponding to the raised braking rank is performed (ST73). When it is determined that the number of times of continuously performing braking control at the same rank is four or more (Y of ST72), and when the accumulated period difference t is less than 0 (N of ST74), the rank is lowered by one (ST76). Then, braking control corresponding to the lowered braking rank is performed (ST73).

[0255] On the other hand, when the accumulated period difference t is greater than 30 [ms] or less than -30 [ms] (Y of ST71), it is determined whether braking control at the same rank has been continuously performed two or more times (ST77). When it is determined that the number of times of continuously performing braking control at the same rank is less than two (N of ST77), braking control corresponding to the current braking rank is performed (ST73).

[0256] If it is determined that braking control at the same rank has been performed consecutively two or more times (ST77's Y), and the accumulated time difference t is 0 or greater (ST78's Y), the rank is increased by two levels (ST79). Then, braking control is performed according to the increased braking rank (ST73). If it is determined that braking control at the same rank has been performed consecutively two or more times (ST77's Y), and the accumulated time difference t is 0 or greater (ST78's N), the rank is decreased by two levels (ST710). Then, braking control is performed according to the decreased braking rank (ST73).

[0257] By performing the rank switching shown in Figures 38 and 39 as described above, the braking force of the electromagnetic brake can be optimized, and as a result, the accuracy of the timekeeping can be improved. In particular, by performing the rank switching shown in Figure 39, the rank can be switched quickly even when the temperature environment changes rapidly, such as when the user of the mechanical watch 1 moves from outdoors to indoors. As a result, the accuracy of the timekeeping can be improved.

[0258] [summary] In each of the embodiments and modifications described above, even if the oscillation frequency of the balance wheel 31 obtained according to the physical structure of the mechanical watch 1 is high, the oscillation frequency of the balance wheel 31 can be adjusted to a lower frequency. In other words, the average value of the oscillation frequency of the balance wheel 31 obtained according to the physical structure of the mechanical watch 1 can be lowered and adjusted to match the period of a preset reference signal OS. This makes it possible to reduce the speed of the balance wheel 31. As a result, it is possible to provide a mechanical watch 1 that maintains accuracy and has high durability.

[0259] It is also possible to adjust the vibration frequency of the balance wheel 31 to a predetermined frequency by manual tuning using a mechanism such as a regulator or free-sprung balance. However, in this case, it is necessary to stop the balance wheel 31, tune it manually, and then move the balance wheel 31 again for measurement. By implementing the braking control of each embodiment and modified example, the vibration frequency of the balance wheel 31 can be adjusted to a predetermined frequency efficiently and easily.

[0260] [others] The rate adjustment means 40 obtains a detection signal based on the operation of a bipolar magnetized permanent magnet 41. If there are components around the permanent magnet 41 that have a magnetic influence, the detection accuracy may decrease. Therefore, it is advisable to use materials that have little magnetic influence for components around the permanent magnet 41. For example, resin materials can be used for the support member 33 and the whisker holder 34. Also, phosphor bronze or brass can be used for the fastener 33a that fixes the support member 33 to the base plate 10. Furthermore, resin, aluminum, or brass can be used for the balance wheel 31.

[0261] Furthermore, as mentioned above, by making the hairspring 32 out of resin to reduce Young's modulus, the magnetic influence on the permanent magnet 41 can be reduced compared to the case where it is made of metal. Also, if the hairspring 32 is made of a magnetic metal, it may be affected by the magnetic influence of the permanent magnet 41, causing displacement of the shape and position of the hairspring 32. In each embodiment and modification, by making the hairspring 32 out of resin, the shape and position of the hairspring 32 itself can be stabilized. In addition, an anti-magnetic plate made of a magnetic material may be provided on the mechanical watch 1 separately. This suppresses disturbance of the forward and reverse rotational motion of the permanent magnet 41 (balance wheel 31) even when an external magnet approaches the mechanical watch 1, and enables stable damping control.

[0262] The braking section tc described with reference to Figures 30 and 31 may be applied to each embodiment and each modified example of each embodiment. That is, for example, in the example described in Figures 10 and 11, a braking section tc in which a speed control pulse is output or an electromagnetic brake is applied may be set in advance, and the control circuit 44 controls the braking force generated in the braking section tc. [Explanation of symbols]

[0263] 1 Mechanical watch, 2 Winding stem, 10 Base plate, 10a Positioning pin, 10b Aperture, 11 Power mainspring, 12 Gear train, 122 Second wheel, 123 Third wheel, 124 Fourth wheel, 13 Hand shaft, 131 Second hand, 20 Escapement mechanism, 21 Escape wheel, 22 Lever, 221 411, n12, n21, n22 notches.

Claims

[Claim 1] Power source and A regulating mechanism including a balance wheel driven by power from the aforementioned power source, and a hairspring that elastically deforms to cause the balance wheel to rotate in forward and reverse directions, A bipolarized permanent magnet that rotates in the forward and reverse directions in conjunction with the forward and reverse rotational motion of the aforementioned balance wheel, Coil and, A rotation detection circuit that detects a detection signal based on a detection voltage generated in the coil due to the movement of the permanent magnet accompanying the forward and reverse movement of the balance wheel, A braking circuit that applies a braking force to the permanent magnet by short-circuiting the terminals of the coil, A control circuit that controls the duration of the braking force based on the detected voltage and the reference signal of the reference signal source, A mechanical watch having [a specific feature / feature].

Images