Electronically controlled mechanical watch

Abstract

To provide an electronically controlled mechanical watch capable of extending duration without increasing the size of a spring.SOLUTION: An electronically controlled mechanical watch includes: a spring; a wheel train; a rotor interlocked with the wheel train; a pointer driven by the wheel train; a magneto coil that generates electric energy from mechanical energy of the spring and brakes the wheel train via the rotor; a charging circuit that executes chopping control that rectifies the electric energy generated by the magneto coil and controls rotation speed of the wheel train on the basis of a control signal; control means that outputs the control signal; a power storage device that is charged with the rectified electric energy; and detection means that detects a mechanical energy amount stored in the spring. When the mechanical energy amount is equal to or greater than a first threshold value, the control means performs first switching processing of switching an inductance value of the magneto coil so that the inductance value is smaller than when the mechanical energy amount is greater than the first threshold value.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an electronically controlled mechanical watch.

Background Art

[0002] In an electronically controlled mechanical watch including a generator that is driven by a mainspring via a wheel train to generate induced power, a pointer coupled to the wheel train, and rotation control means for controlling the rotation period of the generator by chopping control, there is disclosed an electronically controlled mechanical watch that improves braking torque while maintaining the generated voltage at a certain value or more by the chopping control (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the electronically controlled mechanical watch as described above, it is desired to make the duration longer.

Means for Solving the Problems

[0005] The electronic control mechanical clock of the present disclosure includes a mainspring, a wheel train that transmits the mechanical energy of the mainspring, a rotor that interlocks with the wheel train, hands that are driven by the wheel train to display time, a power generation coil that generates electrical energy from the mechanical energy of the mainspring and applies braking to the wheel train via the rotor, a charging circuit that rectifies the electrical energy generated by the power generation coil and performs chopping control to control the rotational speed of the wheel train based on a control signal, control means that outputs the control signal, a power storage device that is charged by the rectified electrical energy, and detection means that detects the amount of mechanical energy stored in the mainspring. The control means executes a first switching process of switching the inductance value of the power generation coil so that it becomes smaller when the amount of mechanical energy is equal to or less than a first threshold value than when the amount of mechanical energy is greater than the first threshold value.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0007] Hereinafter, the electronic control mechanical clock 1 of the embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a front view showing an electronically controlled mechanical watch 1. The electronically controlled mechanical watch 1 is a wristwatch worn on the user's wrist, and includes a cylindrical outer case 2, and a dial 3 is disposed on the inner peripheral side of the outer case 2. Of the two openings of the outer case 2, the opening on the front side is closed by a cover glass, and the opening on the back side is closed by a back cover.

[0008] The electronically controlled mechanical watch 1 includes a movement (not shown) housed in the outer case 2 and hands 4 for displaying time information. The hands 4 are composed of an hour hand 4A, a minute hand 4B, and a second hand 4C. A calendar window 3A is provided in the dial 3, and a date wheel 6 is visible through the calendar window 3A. Further, the dial 3 is provided with hour marks 3B for indicating time and a fan-shaped sub-dial 3C for indicating the duration with a power reserve hand 5.

[0009] A crown 7 is provided on the side surface of the outer case 2. The crown 7 can be pulled out and moved from the 0-stage position pushed into the center of the electronically controlled mechanical watch 1 to the 1-stage position and the 2-stage position. When the crown 7 is pulled to the 1-stage position and rotated, the date wheel 6 can be moved to adjust the date. When the crown 7 is pulled to the 2-stage position, the second hand 4C stops, and when the crown 7 is rotated at the 2-stage position, the hour hand 4A and the minute hand 4B can be moved to adjust the time. The method of correcting the date wheel 6, the hour hand 4A, and the minute hand 4B by the crown 7 is the same as that of a conventional watch, so the description is omitted.

[0010] Also, when the crown 7 is rotated at the 0-stage position, the mainspring 40 described later can be wound up. Then, in conjunction with the winding up of the mainspring 40, the power reserve hand 5 moves. The electronically controlled mechanical watch 1 of the present embodiment can ensure a duration of about 72 hours or more when the mainspring 40 is fully wound up.

[0011] [Schematic Configuration of Electronically Controlled Mechanical Watch] FIG. 2 is a block diagram showing the schematic configuration of the electronically controlled mechanical watch 1. As shown in FIG. 2, the electronically controlled mechanical clock 1 includes an IC 10, a mainspring 40, a speed increasing gear train 50 which is a gear train for transmitting the torque of the mainspring 40, a display unit 60 connected to the speed increasing gear train 50 for displaying time, a generator 70 driven by the torque transmitted through the speed increasing gear train 50, a crystal oscillator 100, a charging circuit 90, and a power storage device 30. The generator 70 also serves as a speed regulator for regulating the rotational speed of the speed increasing gear train 50, as will be described later.

[0012] The IC 10 includes an oscillation circuit 11, a frequency division circuit 12, a rotation detection circuit 13, and a braking control circuit 14. Details of each circuit will be described later.

[0013] The mainspring 40 is wound up by a weight 7 through a winding mechanism (not shown). The winding mechanism includes, for example, a rotating weight or a weight 7 and a winding gear train for transmitting the rotation of the rotating weight or the weight 7 to a square hole wheel that winds up the mainspring 40. The speed increasing gear train 50 is configured to include a plurality of gears that rotate with the mechanical energy stored in the mainspring 40, and drives the hour hand 4A, minute hand 4B, and second hand 4C attached to the shafts of these gears. Also, the speed increasing gear train 50 meshes with the rotor of the generator 70 and rotates the rotor. Although not shown, a winding gear train for winding up the mainspring 40 and a power reserve gear train interlocked with the speed increasing gear train 50 are provided, and a power reserve hand 5 is attached to this power reserve gear train. The display unit 60 is configured to include the hands 4 and the date wheel 6 shown in FIG. 1, and displays the time.

[0014] The power storage device 30 stores the electric charge generated by the generator 70, smoothes the voltage, and supplies it to the IC 10. Therefore, the power storage device 30 functions as a power supply circuit for the IC 10, and the voltage of the power storage device 30 becomes the power supply voltage. The power storage device 30 is composed of a rechargeable secondary battery such as a lithium ion battery or an all-solid-state battery, but it may also be composed of a large-capacity capacitor. As shown in FIG. 3, the power storage device 30 is connected to the charging circuit 90. That is, the power storage device 30 is connected to a first power line 21 that is electrically connected to the VDD terminal of the IC 10 and a second power line 22 that is electrically connected to the VSS terminal of the IC 10. The charging circuit 90 is connected to the first power line 21 and the second power line 22, and the charge generated by the generator 70 is charged into the power storage device 30 via the charging circuit 90, the first power line 21, and the second power line 22.

[0015] [Generator] As shown in FIG. 3, the generator 70 includes a rotor (not shown), a first power generation coil 71, a second power generation coil 72, a first switch 81, a second switch 82, and an inverter 85. The rotor of the generator 70 is driven by the dynamo 40 via the speed increasing gear train 50. The rotor is magnetized with two poles, and in the generator 70, as the rotor rotates, the magnetic flux changes, and an induced voltage Vmg is generated at the terminals of the power generation coil to generate electricity. Here, let the inductance value of the first power generation coil 71 be La and the inductance value of the second power generation coil 72 be Lb. In the present embodiment, since the size of the magnetic core around which each coil is wound, the coil length, the number of turns, etc. are the same, the inductance values La and Lb are set to be substantially the same value. One terminal of the first power generation coil 71 is connected to the charging circuit 90 at point a. The other terminal of the first power generation coil 71 is connected to a parallel circuit at point b. That is, point b is the connection point of one terminal of the second power generation coil 72 and one terminal of the first switch 81. The other terminal of the first switch 81 is connected to the charging circuit 90 at point c. The other terminal of the second power generation coil 72 is connected to one terminal of the second switch 82. The other terminal of the second switch 82 is connected to the charging circuit 90 at point c. Therefore, the second power generation coil 72 and the second switch 82 are connected in series, and the second power generation coil 72 and the second switch 82 connected in series are connected in parallel with the first switch 81. The parallel circuit of the second power generation coil 72 and the second switch 82 and the first switch 81 is connected in series to the first power generation coil 71.

[0016] The first switch 81 is a switch that switches the connection and disconnection between point b and point c, that is, between the first power generation coil 71 and the charging circuit 90. The second switch 82 is a switch that switches the connection and disconnection between the second power generation coil 72 and point c, that is, the charging circuit 90. FIG. 4 shows an example of the first switch 81 and the second switch 82. The first switch 81 is composed of a transmission gate which is an analog switch, and includes an N-channel transistor 811, a P-channel transistor 812, and an inverter 813. The second switch 82 is also composed of a transmission gate like the first switch 81, and includes an N-channel transistor 821, a P-channel transistor 822, and an inverter 823. When the switch control signal SC1 input to the first switch 81 is at the H level, the N-channel transistor 811 and the P-channel transistor 812 are controlled to be in the on state, and when the switch control signal SC1 is at the L level, the N-channel transistor 811 and the P-channel transistor 812 are controlled to be in the off state. Similarly, when the switch control signal SC2 input to the second switch 82 is at the H level, the N-channel transistor 821 and the P-channel transistor 822 are controlled to be in the on state, and when the switch control signal SC2 is at the L level, the N-channel transistor 821 and the P-channel transistor 822 are controlled to be in the off state. Here, the switch control signal SC1 is a signal obtained by inverting the switch control signal SC output from the braking control circuit 14 by the inverter 85, and the switch control signal SC2 is the same signal as the switch control signal SC. Therefore, the opening and closing of the first switch 81 and the second switch 82 can be controlled by the switch control signal SC output from the braking control circuit 14, and the opening and closing states of the first switch 81 and the second switch 82 are always opposite. When the first switch 81 is in the off state, the second switch 82 is in the on state, and when the first switch 81 is in the on state, the second switch 82 is in the off state. When one switch is in the on state, the other switch is in the off state.

[0017] When the switch control signal SC output from the braking control circuit 14 is at the H level, the first switch 81 is in the off state, the second switch 82 is in the on state, and the first power generation coil 71 and the second power generation coil 72 are connected in series to the charging circuit 90. If the inductance value of the power generation coil of the generator 70 in this state is L1, then L1 = La + Lb. When the switch control signal SC output from the braking control circuit 14 is at the L level, the first switch 81 is in the on state, the second switch 82 is in the off state, and only the first power generation coil 71 is connected to the charging circuit 90. If the inductance value of the coil of the generator 70 in this state is L2, then L2 = La. Therefore, L1 > L2.

[0018] In this embodiment, by using transmission gates, which are analog switches, for the first switch 81 and the second switch 82 respectively, with respect to the input signal, that is, the induced voltage generated by the first power generation coil 71 and the second power generation coil 72, the effect of reducing the resistance value when the switch is turned on and improving the linearity of the input / output characteristics can be obtained, and a decrease in power generation efficiency and a decrease in braking force can be prevented. For example, when each switch is composed of a single N-channel transistor, if the input signal is at a potential close to VDD, the resistance value when the switch is turned on becomes large. On the contrary, when each switch is composed of a single P-channel transistor, if the input signal is at a potential close to VSS, the resistance value when the switch is turned on becomes large. In contrast, by configuring each switch as a transmission gate as in this embodiment, the functions of complementing the N-channel transistor and the P-channel transistor are achieved. Therefore, when the input / output voltage fluctuates, compared with the case of using a single transistor as the switch, the effect of reducing the resistance value when the switch is turned on and improving the linearity of the input / output characteristics can be expected.

[0019] As shown in FIG. 3, the generator 70 is connected to a brake circuit 73 controlled by a brake control circuit 14 and a charging circuit 90 via points a and c. Therefore, the electric energy supplied from the generator 70 is charged into the power storage device 30 via the charging circuit 90. At this time, if the first switch 81 is in the off state and the second switch 82 is in the on state, the first power generation coil 71 and the second power generation coil 72 are connected in series to the power storage device 30, and the power storage device 30 is charged with the induced power generated by these power generation coils. Also, if the first switch 81 is in the on state and the second switch 82 is in the off state, the first power generation coil 71 is connected to the power storage device 30 and the second power generation coil 72 is not connected, so the power storage device 30 is charged with the induced power generated by the first power generation coil 71.

[0020] [Brake Circuit] The braking circuit 73 applies a brake to the rotation of the rotor in order to make the generator 70 function as a speed governor. The braking circuit 73 includes a first chopping transistor 731 connected to the output terminal from which the AC signal generated by the generator 70 is output via point c, and a second chopping transistor 732 connected to the output terminal from which the AC signal is output via point a. By turning on each of the chopping transistors 731 and 732, the points a and c are short-circuited to put the power generation coil in a closed-loop state, thereby applying a short brake to the generator 70. Each of these chopping transistors 731 and 732 is connected to the first power line 21 side.

[0021] Each of the chopping transistors 731 and 732 is composed of a P-channel field-effect transistor. The chopping pulse P is input from the braking control circuit 14 to the gates of these chopping transistors 731 and 732. Therefore, each of the chopping transistors 731 and 732 is maintained in the on state while the chopping pulse P is at the L level. On the other hand, while the chopping pulse P is at the H level, each of the chopping transistors 731 and 732 is maintained in the off state, and no brake is applied to the generator 70. That is, the on and off states of each of the chopping transistors 731 and 732 are controlled by the level of the chopping pulse P, and the generator 70 can be chopping-controlled.

[0022] Here, the chopping pulse P is, for example, a signal with a frequency of 128 Hz, and the braking force of the generator 70 is adjusted by changing the duty ratio according to the mechanical energy supplied from the spring 40. That is, when the period of the L level becomes longer in one cycle of the chopping pulse P, the period during which each chopping transistor 731, 732 is maintained in the on state and the short brake is applied becomes longer, and the braking force increases. On the other hand, when the period of the L level becomes shorter in one cycle of the chopping pulse P, the braking force decreases. Therefore, the braking force can be adjusted by the duty ratio of the chopping pulse P.

[0023] [Charging Circuit] The charging circuit 90 is composed of a rectifying circuit such as a step-up rectifier, a full-wave rectifier, a half-wave rectifier, or a transistor rectifier, and boosts and rectifies the AC output from the generator 70 to charge and supply it to the power storage device 30. The charging circuit 90 of the present embodiment includes a first rectifying switch 91, a second rectifying switch 92, diodes 95 and 96, and a boosting capacitor 97. The first rectifying switch 91 is composed of a first rectifying transistor connected in parallel with the first chopping transistor 731 of the brake circuit 73 and having a gate connected to the output terminal MG2. Similarly, the second rectifying switch 92 is composed of a second rectifying transistor connected in parallel with the second chopping transistor 732 and having a gate connected to the output terminal MG1. Each of these rectifying transistors is also composed of a field-effect transistor of Pch. The diodes 95 and 96 may be any unidirectional element that allows current to flow in one direction, and their types are not limited. In particular, in the electronic control type mechanical watch 1, since the electromotive voltage of the generator 70 is small, it is preferable to use a Schottky barrier diode or a silicon diode with a small forward voltage drop and reverse leakage current as the diodes 95 and 96.

[0024] In this embodiment, the first chopping transistor 731, the second chopping transistor 732, the first rectifying switch 91, the second rectifying switch 92, the diode 95, the diode 96, the first switch 81, the second switch 82, and the inverter 85 are configured inside the IC 10. The first power generation coil 71 and the second power generation coil 72 of the generator 70, the boosting capacitor 97, and the power storage device 30 are provided outside the IC 10. In this way, by configuring a part of the charging circuit 90 inside the IC 10, the number of elements mounted on the circuit board of the electronic control type mechanical clock 1 can be reduced, and the cost can be reduced. Note that the capabilities, that is, the sizes, of the chopping transistors 731 and 732 may be set based on the current during chopping in the generator 70.

[0025] Such a charging circuit 90 includes a boosting capacitor 97. Therefore, the charge stored in the boosting capacitor 97 during the charging process is also used to charge the power storage device 30. For this reason, the voltage that can be applied to the IC 10 also increases, and stable operation of the IC 10 can be realized. In this embodiment, the charging circuit 90 is a two-stage boosting rectifying circuit. However, by using diodes and capacitors, the number of boosting stages can be increased, such as three-stage boosting or four-stage boosting, to increase the voltage of the power storage device 30.

[0026] [IC] As shown in FIG. 2, the IC 10 includes an oscillation circuit 11, a frequency division circuit 12, a rotation detection circuit 13, and a braking control circuit 14. Note that IC is an abbreviation for Integrated Circuit.

[0027] The oscillation circuit 11 constitutes a crystal oscillation circuit together with a crystal oscillator 100. Then, the crystal oscillation circuit stops oscillating when the IC applied voltage VDD of the power storage device 30 falls below the oscillation stop voltage, and starts oscillating when the IC applied voltage VDD exceeds the oscillation start voltage. Note that generally, the oscillation start voltage of a crystal oscillator circuit is higher than the oscillation stop voltage in order to generate mechanical vibrations of the crystal. Also, since the frequency division circuit 12 and the braking control circuit 14 described later operate based on the clock signal output by the crystal oscillator circuit, in this embodiment, the oscillation start voltage is equal to the operation start voltage of the IC 10, and the oscillation stop voltage is equal to the drive stop voltage Vstop of the IC 10. The oscillation circuit 11 outputs an oscillation signal of a predetermined frequency generated by the oscillation of the crystal oscillator 100 to the frequency division circuit 12. In this embodiment, the oscillation circuit 11 generates an oscillation signal of 32768 Hz. Therefore, the crystal oscillator circuit including the crystal oscillator 100 and the oscillation circuit 11 is an oscillation means for outputting a clock signal of 32768 Hz.

[0028] The frequency division circuit 12 divides the output of the oscillation circuit 11 to create clock signals of multiple frequencies, and outputs the clock signals necessary for the braking control circuit 14. The clock signal output from the frequency division circuit 12 to the braking control circuit 14 is a reference signal that serves as a reference for the rotation control of the rotor of the generator 70. In this embodiment, since the reference speed of the rotor of the generator 70 is 8 Hz, the frequency division circuit 12 creates a reference signal Fs of 8 Hz and outputs it to the braking control circuit 14.

[0029] The rotation detection circuit 13 is composed of a waveform shaping circuit (not shown) and a monostable multivibrator connected to the generator 70, and outputs a rotation detection signal FG1, which is a rectangular wave representing the rotation frequency (i.e., the rotation speed) of the rotor, from the induced voltage waveform generated in the generator 70 to the braking control circuit 14. The rotor of the generator 70 rotates by the mechanical energy of the spring 40 via the speed increasing gear train 50.

[0030] The braking control circuit 14 compares the rotation detection signal FG1 output from the rotation detection circuit 13 with the reference signal Fs output from the frequency division circuit 12, outputs a chopping pulse P for controlling the speed regulation of the generator 70 to the braking circuit 73 of the generator 70, and outputs a switch control signal SC for switching the inductance value of the generator coil of the generator 70 to the first switch 81 and the second switch 82.

[0031] Next, the power generation by the generator 70 will be described. When the rotor of the generator 70 rotates due to the mechanical energy of the crankshaft 40, an induced voltage is generated in the first power generation coil 71 and the second power generation coil 72. Here, when the induced voltage on the c-side is larger than that on the a-side, a current flows from the c-point through the boosting capacitor 97 and the diode 96 to the a-point while charging the boosting capacitor 97, and since the first rectifying switch 91 is turned on, a current flows from the c-point through the first rectifying switch 91, the power storage device 30, the diodes 95 and 96 to the a-point, and a charge is stored in the power storage device 30. Conversely, when the induced voltage on the a-side is larger than that on the c-side, since the second rectifying switch 92 is turned on, a current flows from the a-point through the second rectifying switch 92, the power storage device 30, the diodes 95, and the boosting capacitor 97 to the c-point, and a charge is stored in the power storage device 30. At that time, the charge stored in the boosting capacitor 97 is also added. When a charge is stored in the power storage device 30 and the voltage of the power storage device 30 exceeds the operation start voltage of the IC 10, the IC 10 starts up. Also, in the generator 70, the power generation efficiency is increased by chopping control described later.

[0032] The IC 10 detects the induced voltage Vmg of the terminal (MG terminal) on the a-side by the rotation detection circuit 13, generates a rotation detection signal FG1 which is a rectangular wave, and outputs it to the rotation detection circuit 13. That is, as shown in FIG. 5, when the induced voltage Vmg of the MG terminal becomes equal to or lower than a predetermined threshold value VROTD, the rotation detection signal FG1 becomes the L level, and when the induced voltage Vmg of the MG terminal becomes larger than the predetermined threshold value VROTD, the rotation detection signal FG1 becomes the H level. That is, when the absolute value of the induced voltage Vmg is equal to or greater than the absolute value of the threshold value VROTD, the rotation detection signal FG1 becomes the L level, and when the absolute value of the induced voltage Vmg is less than the absolute value of the threshold value VROTD, the rotation detection signal FG1 becomes the H level. Since the induced voltage Vmg of the MG terminal changes in conjunction with the rotation of the rotor, the rotation detection signal FG1 becomes a signal for detecting the rotation of the rotor.

[0033] The braking control circuit 14 compares the rotation detection signal FG1 with the reference signal Fs input from the frequency divider circuit 12. When the torque of the generator 70, that is, the mechanical energy, is high, the rotor of the generator 70 is set to rotate faster than the reference signal Fs and is brake-controlled to reach the same speed as the reference signal Fs. In this braking control, the braking control circuit 14 generates a brake signal BS according to the phase difference between the rotation detection signal FG1 and the reference signal Fs. That is, the braking control circuit 14 sets the period from the change timing of the rotation detection signal FG1 from the H level to the L level to the change timing of the reference signal Fs from the H level to the L level as the L level period of the brake signal BS. And the period when the brake signal BS is at the H level is the period for applying a weak brake to the generator 70, and the period when the brake signal BS is at the L level is the period for applying a strong brake to the generator 70, that is, the strong brake time T_break. The braking control circuit 14 switches the duty of the chopping pulse P output to the charging circuit 90 based on the generated brake signal BS. Therefore, the brake signal BS is a control signal for performing braking control, and the braking control circuit 14 is a control means for outputting the brake signal BS which is a control signal. Also, the charging circuit 90 performs chopping control by the chopping pulse P output from the braking control circuit 14. Since the duty of the chopping pulse P is switched based on the brake signal BS which is a control signal, the charging circuit 90 performs chopping control based on the brake signal BS which is a control signal.

[0034] When the spring 40 is wound up and the mechanical energy is high, since the rotation detection signal FG1 advances compared with the reference signal Fs, the strong brake time T_break becomes longer. As a result, the amount of brake applied to the generator 70 increases and the rotation detection signal FG1 slows down, so that the rotational speed of the rotor can be made close to the speed of the reference signal Fs. When the spring 40 is unwound and the mechanical energy decreases, the strong brake time T_break becomes shorter. As a result, the braking force applied to the generator 70 becomes smaller corresponding to the mechanical energy, and over-braking does not occur, so that the rotational speed of the rotor can be made closer to the speed of the reference signal Fs. As described above, the strong brake time T_break is proportional to the output torque of the spring 40 and becomes a value indicating the amount of mechanical energy of the spring 40. Therefore, the braking control circuit 14 can determine whether the amount of mechanical energy of the spring 40 is greater than a predetermined value by determining whether the strong brake time T_break is greater than a predetermined threshold value. Therefore, the braking control circuit 14, which is a control means, also serves as a detection means for detecting the strong brake time T_break, that is, the amount of mechanical energy of the spring 40.

[0035] During the period when the brake signal BS is at the H level, the braking control circuit 14 weakens the brake by shortening the on-periods of the chopping transistors 731 and 732 of the brake circuit 73 to reduce the brake duty. During the period when the brake signal BS is at the L level, the braking control circuit 14 strengthens the brake by lengthening the on-periods of the chopping transistors 731 and 732 of the brake circuit 73 to increase the brake duty. This chopping control for braking is also effective in improving the power generation efficiency. When the chopping transistors 731 and 732 are turned on to short-circuit both ends of the power generation coil, an induced current flows along a path from point c to point a through the first chopping transistor 731 and the second chopping transistor 732, or a path from point a to point c through the second chopping transistor 732 and the first chopping transistor 731, according to the induced voltage at the time of short-circuit. At this time, energy is stored in the power generation coil. When the chopping transistors 731 and 732 are turned off from this state, an electromotive force is generated by self-induction. This electromotive force is added to the induced voltage when charging the aforementioned power storage device 30, and as shown in the graph of Vmg in FIG. 5, a larger electromotive force is generated across the coil compared to the case without chopping control. When the coil is short-circuited, the induced current becomes larger after a certain amount of time has elapsed than immediately after the coil is short-circuited by the transient response. That is, the larger the time constant L / R, the slower the convergence of the transient response. That is, when the rotor brakes for a longer time by chopping control, a larger electromotive force can be obtained, and power generation can be performed efficiently. However, if the braking time is too long, the loss increases. When the chopping transistors 731 and 732 are turned on to short-circuit both ends of the coil, power generation temporarily stops, but the improvement in power generation efficiency by chopping control exceeds that.

[0036] The braking control circuit 14 performs switching control of the first switch 81 and the second switch 82 according to the length of the L level of the brake signal BS, that is, the strong brake time T_break. That is, in the initial state where the IC10 is activated, the braking control circuit 14 sets the switch control signal SC to the H level and compares the strong brake time T_break with the first threshold value Tref1. The first threshold value Tref1 is a threshold value preset according to the strong brake time T_break when the first switch 81 is in the off state, the second switch 82 is in the on state, that is, the inductance value of the coil of the generator 70 is L1, and the spring 40 unwinds and the mechanical energy decreases. When the strong brake time T_break is larger than the first threshold value Tref1, the braking control circuit 14 maintains the switch control signal SC at the H level. When the switch control signal SC is at the H level, as described above, the first switch 81 is in the off state and the second switch 82 is in the on state, and the first power generation coil 71 and the second power generation coil 72 are connected in series to the charging circuit 90, that is, the inductance value of the coil of the generator 70 becomes a large state of L1. When the strong braking time T_break drops below the first threshold value Tref1, the braking control circuit 14 determines that the mechanical energy amount of the generator 40 has dropped below the first threshold value, and performs a first switching process of switching the switch control signal SC to the L level. When the switch control signal SC becomes the L level, as described above, the first switch 81 is switched to the on state, the second switch 82 is switched to the off state, and only the first power generation coil 71 is connected to the charging circuit 90, that is, the inductance value of the coil of the generator 70 is switched to L2. Thereby, the braking force on the rotor weakens, and the strong braking time T_break becomes longer. As the strong braking time T_break becomes longer, the generated electromotive voltage generated by the chopping control becomes larger, and the power generation efficiency is improved.

[0037] When the switch control signal SC is at the L level, the braking control circuit 14 compares the strong braking time T_break with the second threshold value Tref2. The second threshold value Tref2 is a time longer than the first threshold value Tref1, and is set to a time longer than the strong braking time T_break required immediately after the inductance value is switched to L2. With this setting, frequent changes in the switch control signal SC, that is, frequent switching of the first switch 81 and the second switch 82 can be suppressed. When the strong braking time T_break is equal to or less than the second threshold value Tref2, the braking control circuit 14 maintains the switch control signal SC at the L level, and also maintains the inductance value of the coil of the generator 70 at L2. When the strong brake time T_break becomes greater than the second threshold value Tref2 due to, for example, the winding up of the generator 40, the braking control circuit 14 determines that the mechanical energy amount of the generator 40 has increased beyond the second threshold value, and performs a second switching process of switching the switch control signal SC to the H level. When the switch control signal SC becomes the H level, as described above, the first switch 81 switches to the off state and the second switch 82 switches to the on state, and the inductance value of the coil of the generator 70 increases to L1. As a result, even when the generator 40 is fully wound up, a braking force capable of performing speed control of the generator 70 can be obtained. Note that in accordance with the switching of the inductance value from L2 to L1, the threshold value of the brake signal switches from the second threshold value Tref2 to the first threshold value Tref1.

[0038] FIG. 6 is a graph showing the generator torque which is the output torque of the generator 40, the voltage of the power supply circuit of the IC 10, and the strong brake time, and a graph showing the relationship between the braking torque and the inductance value. The output torque M of the generator 40 becomes the highest Tmax immediately after the generator 40 is fully wound up, and decreases as the generator 40 unwinds over time. VL1 in the graph of the power supply voltage indicates the generated voltage when the inductance value is L1, and VL2 indicates the generated voltage when the inductance value is L2. As shown in these graphs, the generated voltage depends on the output torque of the generator 40 and the inductance value of the generator coil. V0 in the graph of the power supply voltage is an example in the case where the power storage device 30 is configured by a secondary battery, and will be described later. First, an example in the case where the power storage device 30 is configured by a capacitor will be described. When the power storage device 30 is configured by a capacitor, the generated voltages VL1 and VL2 become the power supply voltage of the IC 10. Here, when the generated voltages VL1 and VL2 are compared, at the time when the output torque is Tmax, the generated voltage VL1 is lower than the generated voltage VL2, and the time until it drops below the IC drive stop voltage is also shorter for the generated voltage VL1 than for the generated voltage VL2. Just before the power supply voltage drops below the drive stop voltage of IC10 and the generator 70, which is a speed regulator, becomes uncontrollable, the spring torque at that moment, that is, the minimum spring torque capable of displaying the correct time, is defined as the minimum adjustable speed torque Tg0. The time from when the spring torque changes from Tmax to Tg0 is called the duration of the electronic control type mechanical clock 1, and increasing this duration is an important point for enhancing the commercial value of the electronic control type mechanical clock 1.

[0039] As shown in FIG. 6, when comparing the minimum adjustable speed torque Tg0_1 when the inductance value is L1 and the minimum adjustable speed torque Tg0_2 when the inductance value is L2, since Tg0_1 > Tg0_2, the inductance value L2 can result in a longer duration T1. Also, in order to adjust the speed of the rotor, it is necessary to make the braking force Tb greater than the output torque of the spring 40. A typical method of increasing the braking force Tb is to increase the inductance value of the coil. On the other hand, when the inductance value is increased, as described above, the minimum adjustable speed torque Tg0 increases. When the inductance value is increased, even without applying braking by chopping control, the rotor will receive a greater braking force due to the magnetic field generated by the induced current flowing through the coil. Then, the braking period by chopping control becomes shorter, and sufficient energy cannot be stored in the coil, so the electromotive force due to the self - induction effect when the short - circuit of the coil is released decreases. That is, in order to drive IC10, a greater spring torque is required, so the minimum adjustable speed torque Tg0 increases. As described above, the braking force Tb and the minimum adjustable speed torque Tg0 are in a trade - off relationship.

[0040] Therefore, in this embodiment, during the period when the spring torque is high, as described above, the inductance value of the power generation coil is set to L1 so that a braking force Tb1 greater than the spring torque Tmax can be obtained. On the other hand, when the spring torque decreases and the strong braking time T_break drops below the first threshold value Tref1, the first switching process is executed, and the inductance value of the power generation coil is switched to L2. As a result, since the braking force becomes smaller, the period during which the coil is short-circuited becomes longer. That is, the braking duty becomes larger. Then, since the energy stored in the coil becomes larger, the electromotive force when the coil is released becomes larger, and the voltage of the power supply circuit rises. Therefore, the minimum adjustable speed torque Tg0 is lowered, and the duration extends to T1. Next, the differences from the case of using the capacitor described above will be described for the case where a secondary battery is used as the power storage device 30 as in this embodiment. When a secondary battery is used as the power storage device 30, even if the generated voltage drops, the voltage of the power storage device 30 does not drop. The power supply voltage becomes V0 in the graph of the power supply voltage. Therefore, the IC10 can continue the speed control even when the generated voltage drops, and can display the correct time until the rotational speed of the rotor falls below the reference signal Fs. In this case, the minimum adjustable speed torque Tg0_3 is the spring torque immediately before the rotational speed of the rotor lags behind the reference signal Fs and the correct time can no longer be displayed. Similarly, even when the power storage device 30 is a large-capacity power supply device such as a secondary battery, the braking force Tb and the minimum adjustable speed torque Tg0 are in a trade-off relationship. If the braking force Tb is increased in accordance with the maximum output torque of the spring 40, the rotor receives a large braking force, so that an excessive brake is applied and the reference speed is exceeded, making it impossible to perform appropriate speed adjustment. That is, the minimum adjustable speed torque Tg0 increases. In this embodiment, by switching the inductance value of the power generation coil from L1 to L2, the minimum adjustable speed torque Tg0 can be lowered and the duration can be extended to T2. Furthermore, since the minimum adjustable speed torque Tg0_3 is smaller than the minimum adjustable speed torque Tg0_2, the duration T2 until the minimum adjustable speed torque Tg0_3 decreases can be made longer than the duration T1. In the mainspring torque region where the generated voltage exceeds the voltage of the secondary battery which is the power storage device 30, since the secondary battery can be charged, the time until the voltage of the power storage device 30 drops below the drive stop voltage of the IC 10 can also be extended.

[0041] [Effects of the Embodiment] When the mechanical energy of the mainspring 40 is large, the electronic control type mechanical clock 1 can increase the inductance value of the power generation coil to L1 and increase the braking force, so that a mainspring 40 with a large mainspring torque Tmax when fully wound can be used. Also, when the mainspring 40 unwinds and the mechanical energy becomes small, the inductance value of the power generation coil is switched to L2 and decreased, and the braking force can be decreased. Therefore, the coil short - circuit time of the chopping control can be lengthened to increase the electromotive force and improve the power generation efficiency. Therefore, the adjustable speed range increases from the region with a large mainspring torque to the region with a low torque, and the duration of the electronic control type mechanical clock 1 can be extended. Also, since the braking force Tb can be set with a margin with respect to the mainspring torque Tmax, the yield during mass production of the electronic control type mechanical clock 1 can also be improved.

[0042] By simply comparing the strong braking time T_break with the first threshold value Tref1 and the second threshold value Tref2, the magnitude of the mechanical energy amount of the mainspring 40 can be determined. Thus, no additional circuits, sensors, etc. are required, and the mechanical energy amount of the mainspring 40 can be easily judged. Also, by judging the magnitude of the mechanical energy amount of the mainspring 40 by the L - level period of the braking signal BS, that is, the strong braking time T_break, a judgment considering variations can be made. For example, if trying to judge the mechanical energy amount of the mainspring 40 by the number of rotations of the rotor, the excess or deficiency of braking at a certain number of rotations cannot be considered. Therefore, it is necessary to set a number of rotations with a margin in consideration of mass production variations (mainspring torque, transmission efficiency, coil resistance, inductance value, magnetic flux density, etc.). On the one hand, by determining based on the strong braking time T_break of the brake signal BS, it is possible to make a determination considering the excess or deficiency of the brake. For example, when the strong braking time T_break is the longest, it can be determined that the braking force is insufficient, and when the strong braking time T_break is the shortest, it can be determined that the braking force is too large. Therefore, the switching timing of the inductance value of the coil can be appropriately determined. In practice, instead of switching when the strong braking time T_break is the maximum or minimum, by comparing with the first threshold value Tref1 and the second threshold value Tref2, the switching is performed before that. Even if there are mass production variations, the inductance value of the coil can be appropriately switched.

[0043] The electronically controlled mechanical clock 1 can switch the inductance value of the coil used for brake control by adding a second power generation coil 72, a first switch 81, and a second switch 82 to the conventional structure. Also, by configuring the first switch 81, the second switch 82, and the inverter 85 in the IC10, on the circuit board, it can be wired with only one wiring pattern from the point b between the first power generation coil 71 and the second power generation coil 72 to the IC10, and only one terminal needs to be added to the IC10. Therefore, the wiring efficiency can be improved.

[0044] Since transmission gates are used for the first switch 81 and the second switch 82, an output signal with less loss can be expected for the input signal, and a decrease in power generation efficiency and a decrease in braking force can be prevented.

[0045] Since the power storage device 30 is configured with a secondary battery, there is no need to worry about the power generation efficiency of the generator 70. That is, in a region where the mechanical energy at the end of the unwinding of the spring 40 is small, the linked magnetic flux can be reduced to the limit where the rotation of the rotor can be detected. Therefore, the minimum adjustable speed torque Tg0 can be reduced, and the duration can be extended. Also, by using a secondary battery, in a region where the generated voltage exceeds the voltage of the secondary battery, the power storage device 30, which is a secondary battery, can be charged, so the time until the voltage of the secondary battery drops below the IC drive stop voltage can be extended.

[0046] [Modification Example] Note that the present disclosure is not limited to the above-described embodiments, and modifications, improvements, etc. within the scope that can achieve the object of the present disclosure are included in the present disclosure. The configuration for switching the inductance value of the power generation coil is not limited to the configuration of the above-described embodiment. For example, the number of turns of the coil is set so that the inductance value LA of the first power generation coil 71 and the inductance value LB of the second power generation coil 72 satisfy LA > LB. When the mechanical energy amount of the spring 40 is greater than the first threshold value, only the first power generation coil 71 is connected to the charging circuit 90 and the inductance value of the power generation coil is set to LA. When the mechanical energy amount of the spring 40 is less than or equal to the first threshold value, only the second power generation coil 72 may be connected to the charging circuit 90 and the inductance value of the power generation coil may be set to LB. Also, the inductance value of the power generation coil may be switched in three or more steps according to the mechanical energy amount of the spring 40. For example, the inductance value of the power generation coil may be switched in three steps of LA, LB, and LA + LB. Furthermore, the inductance value of the power generation coil may be switched by switching a plurality of power generation coils between a series connection state and a parallel connection state. The configuration for detecting the mechanical energy amount of the spring 40 is not limited to the configuration of comparing the strong brake time T_break with each threshold value.

[0047] The power storage device 30 is not limited to being configured by a secondary battery and may be configured by a capacitor. Even when the power storage device 30 is configured by a capacitor, as described above, the duration can be extended to T1 by switching the inductance values of the power generation coils to L1 and L2 according to the amount of mechanical energy of the spring 40.

[0048] The first threshold value Tref1 used in the first switching process and the second threshold value Tref2 used in the second switching process were different values, but they may be the same value. Also, as a condition for executing the first switching process, it is sufficient that at least the braking force after switching the inductance value of the power generation coil to a small value can adjust the speed of the wheel train by exceeding the output torque of the spring 40.

[0049] The braking control circuit 14 is not limited to executing the first switching process and the second switching process, and may execute only the first switching process. For example, in an electronically controlled mechanical watch that does not have an automatic winding mechanism for the spring 40 by a rotating weight, after the spring 40 unwinds and the IC10 stops, when the IC10 restarts by winding up the spring 40 by rotating the rotor 7, the first switch 81 and the second switch 82 may be configured to be initially set so that the inductance of the power generation coil becomes L1.

[0050] [Summary] The electronic control mechanical clock of the present disclosure includes a mainspring, a wheel train that transmits the mechanical energy of the mainspring, a rotor that interlocks with the wheel train, hands that are driven by the wheel train to display time, a power generation coil that generates electrical energy from the mechanical energy of the mainspring and applies braking to the wheel train via the rotor, a charging circuit that rectifies the electrical energy generated by the power generation coil and performs chopping control to control the rotational speed of the wheel train based on a control signal, control means that outputs the control signal, a power storage device that is charged by the rectified electrical energy, and detection means that detects the amount of mechanical energy stored in the mainspring. The control means executes a first switching process of switching the inductance value of the power generation coil to be smaller when the amount of mechanical energy is equal to or less than a first threshold value than when the amount of mechanical energy is greater than the first threshold value. According to the electronic control mechanical clock of the present disclosure, when the amount of mechanical energy of the mainspring detected by the detection means drops below the first threshold value, the control means executes a first switching process of switching the inductance value of the power generation coil to a small value. Therefore, when the mechanical energy of the mainspring, that is, the output torque, decreases, the power generation amount can be increased or the braking force can be reduced, and the duration of the electronic control mechanical clock can be extended. Also, before the execution of the first switching process, the inductance value of the power generation coil that applies braking to the wheel train via the rotor can be increased, so that the braking force required for speed regulation of the wheel train can be ensured from the time when the mainspring is fully wound up and the output torque of the mainspring reaches the maximum.

[0051] In the electronic control mechanical clock of the present disclosure, it is preferable that when the detection means detects that the amount of mechanical energy is greater than a second threshold value, the control means executes a second switching process of switching the inductance value of the power generation coil to be larger than when the amount of mechanical energy is equal to or less than the second threshold value. According to the electronically controlled mechanical watch of the present disclosure, when it is detected that the amount of mechanical energy of the mainspring detected by the detection means is greater than the second threshold value, the control means executes a second switching process for switching the inductance value of the power generation coil to a large value. Therefore, when the output torque increases as the mainspring is wound up, the braking force required for the speed regulation of the wheel train can be ensured.

[0052] In the electronically controlled mechanical watch of the present disclosure, the power generation coil includes a first power generation coil and a second power generation coil. The first switching process is a process of disconnecting the charging circuit from the second power generation coil and connecting the charging circuit to the first power generation coil. The second switching process is preferably a process of connecting the first power generation coil and the second power generation coil in series to the charging circuit. According to the electronically controlled mechanical watch of the present disclosure, by switching the connection state between the first power generation coil and the second power generation coil in the first switching process and the second switching process, the inductance value can be easily switched. In addition, since the switching of the connection state of each coil only requires providing wiring and switches for connection, an increase in area on the circuit board can also be suppressed.

[0053] In the electronically controlled mechanical watch of the present disclosure, it includes a first switch for switching the connection and disconnection between the first power generation coil and the charging circuit, and a second switch for switching the connection and disconnection between the second power generation coil and the charging circuit. The first switch, the second power generation coil, and the second switch are connected in parallel to each other and are connected in series to the first power generation coil. The first switching process is a process of connecting the first switch and disconnecting the second switch. The second switching process is preferably a process of disconnecting the first switch and connecting the second switch. According to the electronically controlled mechanical watch of the present disclosure, by adding a second power generation coil, a first switch, and a second switch to the conventional structure, it is possible to switch the inductance value of the coil used for brake control. Further, by configuring the first switch and the second switch inside the IC, only one wiring pattern for wiring from the contact points of the first power generation coil and the second power generation coil to the IC needs to be wired on the circuit board, and only one terminal needs to be added to the IC, so the wiring efficiency can be improved.

[0054] In the electronically controlled mechanical watch of the present disclosure, the first switch and the second switch may each be constituted by a transmission gate. According to the electronically controlled mechanical watch of the present disclosure, since the transmission gate is used for the first switch and the second switch, an output signal with less loss can be expected for the input signal, and a decrease in power generation efficiency and a decrease in braking force can be prevented.

[0055] In the electronically controlled mechanical watch of the present disclosure, the control means outputs the control signal based on the phase difference between the detection signal of the rotation speed of the wheel train and a reference signal, and the detection means preferably detects the amount of mechanical energy stored in the mainspring based on the control signal. According to the electronically controlled mechanical watch of the present disclosure, the control means outputs a control signal for brake control based on the phase difference between the detection signal of the rotation speed of the wheel train and the reference signal. And since the detection means can detect the amount of mechanical energy stored in the mainspring based on the control signal, no additional circuits, sensors, etc. are required to detect the mechanical energy of the mainspring, and the amount of mechanical energy of the mainspring can be easily determined.

[0056] In the electronically controlled mechanical watch of the present disclosure, the power storage device is preferably a secondary battery. According to the electronically controlled mechanical watch of the present disclosure, since the power storage device is configured by a secondary battery, the interlinkage magnetic flux can be reduced to the limit where the rotation of the rotor can be detected in a region where the mechanical energy at the end of the winding and unwinding of the mainspring is small. Therefore, the minimum adjustable speed torque can be reduced and the duration can be extended. Further, by using the secondary battery, in a region where the generated voltage exceeds the voltage of the secondary battery, the power storage device, which is the secondary battery, can be charged, so that the time until the capacity of the secondary battery runs out can be extended.

Description of Signs

[0057] 1... Electronically controlled mechanical watch, 4... Hands, 10... IC, 13... Rotation detection circuit, 14... Braking control circuit, 30... Power storage device, 40... Mainspring, 50... Gear train for speed increase, 60... Display unit, 70... Generator, 71... First power generation coil, 72... Second power generation coil, 73... Brake circuit, 81... First switch, 82... Second switch, 90... Charging circuit.

Claims

1. A mainspring; A gear train for transmitting the mechanical energy of the mainspring; A rotor interlocked with the gear train; A pointer driven by the gear train to indicate time; A power generation coil that generates electrical energy from the mechanical energy of the mainspring and applies braking to the gear train via the rotor; A charging circuit that rectifies the electrical energy generated by the power generation coil based on a control signal and performs chopping control to control the rotational speed of the gear train; Control means for outputting the control signal; A power storage device charged by the rectified electrical energy; Detection means for detecting the amount of mechanical energy stored in the mainspring, comprising: When the amount of mechanical energy is equal to or less than a first threshold value, the control means executes a first switching process of switching the inductance value of the power generation coil to be smaller than when the amount of mechanical energy is greater than the first threshold value. An electronically controlled mechanical clock characterized by the above.

2. In the electronically controlled mechanical clock according to Claim 1, When the detection means detects that the amount of mechanical energy is greater than a second threshold value, the control means executes a second switching process of switching the inductance value of the power generation coil to be larger than when the amount of mechanical energy is equal to or less than the second threshold value. An electronically controlled mechanical clock characterized by the above.

3. In the electronically controlled mechanical clock according to Claim 2, The power generation coil includes a first power generation coil and a second power generation coil, The first switching process is A process of disconnecting the charging circuit and the second power generation coil and connecting the charging circuit and the first power generation coil. The second switching process is A process of connecting the first power generation coil and the second power generation coil in series to the charging circuit. An electronically controlled mechanical clock characterized by the above.

4. In the electronically controlled mechanical clock according to Claim 3, A first switch for switching the connection and disconnection between the first power generation coil and the charging circuit; A second switch for switching the connection and disconnection between the second power generation coil and the charging circuit, comprising: The first switch, the second power generation coil, and the second switch are connected in parallel to each other and in series to the first power generation coil. The first switching process is a process of connecting the first switch and disconnecting the second switch. The second switching process is a process of disconnecting the first switch and connecting the second switch. An electronically controlled mechanical timepiece characterized by the above.

5. In the electronically controlled mechanical timepiece according to claim 4, the first switch and the second switch are each composed of a transmission gate. An electronically controlled mechanical timepiece characterized by the above.

6. In the electronically controlled mechanical timepiece according to claim 1, the control means outputs the control signal based on a phase difference between a detection signal of the rotational speed of the gear train and a reference signal, and the detection means detects the amount of mechanical energy stored in the mainspring based on the control signal. An electronically controlled mechanical timepiece characterized by the above.

7. In the electronically controlled mechanical timepiece according to claim 1, the power storage device is a secondary battery. An electronically controlled mechanical timepiece characterized by the above.

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