阅读说明：本技术 电子钟表、机芯以及电机控制电路 (Electronic timepiece, movement, and motor control circuit ) 是由 长滨玲子 川口孝 于 2020-03-04 设计创作，主要内容包括：本发明提供一种即使在电机的负载发生了变动的情况下,也能够以适当的驱动条件来进行驱动的电子钟表。电子钟表具备：电机,其具有线圈；驱动器,其被控制为,向所述线圈供给驱动电流的导通状态、以及不供给所述驱动电流的断开状态；驱动器控制部,其根据流向所述线圈的电流值和控制参数而将所述驱动器控制为所述导通状态或所述断开状态；控制参数设定部,其基于所述驱动器控制部的所述导通状态或所述断开状态的控制状态,从而维持或变更所述控制参数。(The invention provides an electronic timepiece capable of driving under appropriate driving conditions even when the load of a motor varies. An electronic timepiece includes: a motor having a coil; a driver controlled to be in an on state in which a drive current is supplied to the coil and in an off state in which the drive current is not supplied; a driver control unit that controls the driver to be in the on state or the off state according to a current value flowing through the coil and a control parameter; and a control parameter setting unit that maintains or changes the control parameter based on a control state of the on state or the off state of the driver control unit.)

1. An electronic timepiece is characterized by comprising:

a motor having a coil;

a driver controlled to be in an on state in which a drive current is supplied to the coil and in an off state in which the drive current is not supplied;

a driver control unit that controls the driver to be in the on state or the off state according to a current value flowing through the coil and a control parameter;

and a control parameter setting unit that maintains or changes the control parameter based on a control state of the on state or the off state of the driver control unit.

2. The electronic timepiece according to claim 1,

the driver control unit includes a lower limit current detection unit that compares the current value with a lower limit current threshold and detects whether or not the current value is smaller than the lower limit current threshold, and controls the driver from the off state to the on state based on a detection result of the lower limit current detection unit,

the control parameter setting unit maintains or changes the control parameter based on an off time, which is a duration of the off state of the actuator.

3. The electronic timepiece according to claim 1,

the driver control unit includes an upper limit current detection unit that compares the current value with an upper limit current threshold value and detects whether or not the current value exceeds the upper limit current threshold value, and controls the driver from the on state to the off state based on a detection result of the upper limit current detection unit,

the control parameter setting unit maintains or changes the control parameter based on an on time, which is a duration of the on state of the driver.

4. The electronic timepiece according to claim 1,

the control parameter setting unit maintains or changes the control parameter based on an elapsed time from when the driver control unit starts supply of the drive current to the driver until a polarity switching condition for switching the polarity of the drive current is satisfied.

5. The electronic timepiece according to claim 1,

an upper limit current detection unit that compares a current value flowing to the coil with an upper limit current threshold value and detects whether or not the current value exceeds the upper limit current threshold value,

the control parameter is the upper current threshold.

6. The electronic timepiece according to claim 1,

a lower limit current detection unit that compares a current value flowing to the coil with a lower limit current threshold value and detects whether or not the current value is smaller than the lower limit current threshold value,

the control parameter is the lower current threshold.

7. The electronic timepiece according to claim 1,

the control parameter is a polarity switching condition for switching the polarity of the drive current.

8. The electronic timepiece according to claim 1,

the driver control unit includes:

an upper limit current detection unit that compares a current value flowing to the coil with an upper limit current threshold value and detects whether or not the current value exceeds the upper limit current threshold value;

a lower limit current detection unit that compares a current value flowing to the coil with a lower limit current threshold value and detects whether or not the current value is smaller than the lower limit current threshold value,

the driver control section controls the driver to the off state when the upper limit current detection section detects that the current value exceeds the upper limit current threshold,

the driver control section controls the driver to the on state when the lower limit current detection section detects that the current value is smaller than the lower limit current threshold,

the driver control unit switches the polarity of the drive current when an on time, which is a duration of the on state of the driver, or an off time, which is a duration of the off state of the driver, meets a preset polarity switching condition,

the control parameter is the upper limit current threshold or the lower limit current threshold,

the control parameter setting unit maintains or changes the control parameter based on the on time or the off time.

9. The electronic timepiece according to claim 1,

the driver control unit includes:

an upper limit current detection unit that compares a current value flowing to the coil with an upper limit current threshold value and detects whether or not the current value exceeds the upper limit current threshold value;

a lower limit current detection unit that compares a current value flowing to the coil with a lower limit current threshold value and detects whether or not the current value is smaller than the lower limit current threshold value,

the driver control section controls the driver to the off state when the upper limit current detection section detects that the current value exceeds the upper limit current threshold,

the driver control section controls the driver to the on state when the lower limit current detection section detects that the current value is smaller than the lower limit current threshold,

the driver control unit switches the polarity of the drive current when an on time, which is a duration of the on state of the driver, or an off time, which is a duration of the off state of the driver, satisfies a preset polarity switching condition and an elapsed time from when the driver control unit starts supplying the drive current to the driver until when the polarity switching condition is detected to be satisfied is equal to or greater than a threshold value,

the control parameter is the upper limit current threshold or the lower limit current threshold,

the control parameter setting unit maintains or changes the control parameter based on the on time or the off time.

10. The electronic timepiece according to claim 9,

the control parameter setting unit increases the upper limit current threshold when the on time or the off time satisfies the polarity switching condition set in advance and the elapsed time is less than a threshold.

11. The electronic timepiece according to claim 9,

the control parameter setting unit decreases the upper limit current threshold when the number of times of the on state and the off state until the elapsed time becomes equal to or greater than a threshold is less than a first number of times,

when the number of times of the on state and the off state until the elapsed time becomes equal to or greater than a threshold value is greater than a second number of times, which is set to be equal to or greater than the first number of times, the control parameter setting unit increases the upper limit current threshold value.

12. The electronic timepiece according to claim 8,

the driver control unit controls the driver so that the polarity of the drive current is switched every step when a start signal for starting the driving of the motor is inputted,

the control parameter setting unit sets the control parameter after the second step based on the on state or the off state in the control of the first step,

the control parameter setting unit executes the setting process of the control parameter so as to operate at a predetermined time interval until a stop signal for stopping the driving of the motor is input.

13. A movement is characterized by comprising:

a motor having a coil;

a driver controlled to be in an on state in which a drive current is supplied to the coil and in an off state in which the drive current is not supplied;

a driver control unit that controls the driver to be in the on state or the off state according to a current value flowing through the coil and a control parameter;

and a control parameter setting unit that maintains or changes the control parameter based on a control state of the on state or the off state of the driver control unit.

14. A motor control circuit is characterized by comprising:

a driver controlled to be in an on state in which a drive current is supplied to a coil of a motor and to be in an off state in which the drive current is not supplied;

a driver control unit that controls the driver to be in the on state or the off state according to a current value flowing through the coil and a control parameter;

and a control parameter setting unit that maintains or changes the control parameter based on a control state of the on state or the off state of the driver control unit.

Technical Field

The invention relates to an electronic timepiece, a movement, and a motor control circuit.

Background

Patent document 1 discloses a technique of: the control device controls the rotation of the motor by cutting off the supply of the current to the coil of the motor if the current flowing to the coil exceeds the upper threshold, turning on the supply of the current to the coil of the motor if the current flowing to the coil is lower than the lower threshold, and estimating the position of the rotor of the motor based on the on time during which the supply of power is continued or the off time during which the supply of power is continued to be stopped.

The load of the motor may vary due to a change over time in the oil used in the motor or a change in the ambient temperature in which the motor is used, and in the control technique described above, the variation in the load is not considered, and the motor may not be driven under appropriate driving conditions. Therefore, when the load of the motor is small, the motor may be driven with high power consumption to consume unnecessary power consumption, or when the load is large, the motor may be driven with low power consumption to slow the rotation of the rotor.

Patent document 1: japanese Kokai publication Hei-2009-542186

Disclosure of Invention

The electronic timepiece of the present disclosure includes: a motor having a coil; a driver controlled to be in an on state in which a drive current is supplied to the coil and in an off state in which the drive current is not supplied; a driver control unit that controls the driver to be in the on state or the off state according to a current value flowing through the coil and a control parameter; and a control parameter setting unit that maintains or changes the control parameter based on a control state of the on state or the off state of the driver control unit.

In the electronic timepiece of the present disclosure, it is preferable that the driver control unit includes a lower limit current detection unit that compares the current value with a lower limit current threshold and detects whether or not the current value is smaller than the lower limit current threshold, the driver control unit controls the driver from the off state to the on state based on a detection result of the lower limit current detection unit, and the control parameter setting unit maintains or changes the control parameter based on an off time that is a duration of the off state of the driver.

In the electronic timepiece of the present disclosure, it is preferable that the driver control unit includes an upper limit current detection unit that compares the current value with an upper limit current threshold and detects whether or not the current value exceeds the upper limit current threshold, the driver control unit controls the driver from the on state to the off state based on a detection result of the upper limit current detection unit, and the control parameter setting unit maintains or changes the control parameter based on an on time that is a duration of the on state of the driver.

In the electronic timepiece of the present disclosure, it is preferable that the control parameter setting unit maintains or changes the control parameter based on an elapsed time from when the driver control unit starts the supply of the drive current to the driver until a polarity switching condition for switching the polarity of the drive current is satisfied.

In the electronic timepiece of the present disclosure, an upper limit current detection unit may be provided that compares a current value flowing through the coil with an upper limit current threshold value and detects whether or not the current value exceeds the upper limit current threshold value, and the control parameter may be the upper limit current threshold value.

In the electronic timepiece of the present disclosure, a lower limit current detection unit may be provided that compares a current value flowing through the coil with a lower limit current threshold value and detects whether or not the current value is smaller than the lower limit current threshold value, and the control parameter may be the lower limit current threshold value.

In the electronic timepiece of the present disclosure, the control parameter may be a polarity switching condition for switching the polarity of the drive current.

In the electronic timepiece of the present disclosure, it is preferable that the driver control unit includes: an upper limit current detection unit that compares a current value flowing to the coil with an upper limit current threshold value and detects whether or not the current value exceeds the upper limit current threshold value; a lower limit current detection unit that compares a current value flowing to the coil with a lower limit current threshold value and detects whether or not the current value is smaller than the lower limit current threshold value, wherein the driver control unit controls the driver to the off state when the upper limit current detection unit detects that the current value exceeds the upper limit current threshold value, and controls the driver to the on state when the lower limit current detection unit detects that the current value is smaller than the lower limit current threshold value, and wherein the driver control unit switches the polarity of the drive current when an on time, which is a duration of the on state of the driver, or an off time, which is a duration of the off state of the driver, meets a preset polarity switching condition, the control parameter is the upper limit current threshold or the lower limit current threshold, and the control parameter setting unit maintains or changes the control parameter based on the on time or the off time.

In the electronic timepiece of the present disclosure, it is preferable that the driver control unit includes: an upper limit current detection unit that compares a current value flowing to the coil with an upper limit current threshold value and detects whether or not the current value exceeds the upper limit current threshold value; a lower limit current detection unit that compares a current value flowing to the coil with a lower limit current threshold value and detects whether or not the current value is smaller than the lower limit current threshold value, wherein the driver control unit controls the driver to the off state when the upper limit current detection unit detects that the current value exceeds the upper limit current threshold value, controls the driver to the on state when the lower limit current detection unit detects that the current value is smaller than the lower limit current threshold value, and controls the driver to the on state when an on time, which is a duration of the on state of the driver, or an off time, which is a duration of the off state of the driver, satisfies a preset polarity switching condition, and an elapsed time from when the driver control unit starts supply of the drive current to the driver until the polarity switching condition is detected When the current is equal to or larger than a threshold value, the driver control unit switches the polarity of the drive current, the control parameter is the upper limit current threshold value or the lower limit current threshold value, and the control parameter setting unit maintains or changes the control parameter based on the on time or the off time.

In the electronic timepiece of the present disclosure, it is preferable that the control parameter setting unit increases the upper limit current threshold when the on time or the off time satisfies the polarity switching condition set in advance and the elapsed time is less than a threshold.

In the electronic timepiece of the present disclosure, it is preferable that the control parameter setting unit decreases the upper limit current threshold when the number of times of the on state and the off state until the elapsed time becomes equal to or greater than a threshold is less than a first number of times, and increases the upper limit current threshold when the number of times of the on state and the off state until the elapsed time becomes equal to or greater than the threshold is more than a second number of times, the second number of times being set to be equal to or greater than the first number of times.

In the electronic timepiece of the present disclosure, it is preferable that the driver control unit controls the driver so as to switch the polarity of the drive current in each step when a start signal to start driving the motor is input, the control parameter setting unit sets the control parameter after a second step based on the on state or the off state in the first step, and the control parameter setting unit executes the process of setting the control parameter so as to operate at a predetermined time interval until a stop signal to stop driving the motor is input.

The disclosed movement is characterized by being provided with: a motor having a coil; a driver controlled to be in an on state in which a drive current is supplied to the coil and in an off state in which the drive current is not supplied; a driver control unit that controls the driver to be in the on state or the off state according to a current value flowing through the coil and a control parameter; and a control parameter setting unit that maintains or changes the control parameter based on a control state of the on state or the off state of the driver control unit.

The motor control circuit of the present disclosure is characterized by comprising: a driver controlled to be in an on state in which a drive current is supplied to a coil of a motor and to be in an off state in which the drive current is not supplied; a driver control unit that controls the driver to be in the on state or the off state according to a current value flowing through the coil and a control parameter; and a control parameter setting unit that maintains or changes the control parameter based on a control state of the on state or the off state of the driver control unit.

Drawings

Fig. 1 is a front view of an electronic timepiece according to a first embodiment.

Fig. 2 is a circuit diagram showing a circuit configuration of the electronic timepiece of the first embodiment.

Fig. 3 is a configuration diagram showing the configuration of an IC of the electronic timepiece of the first embodiment.

Fig. 4 is a circuit diagram showing a configuration of a motor control circuit of the electronic timepiece according to the first embodiment.

Fig. 5 is a flowchart for explaining the motor control process according to the first embodiment.

Fig. 6 is a flowchart illustrating the load determination process according to the first embodiment.

Fig. 7 is a graph showing changes in current, voltage, and rotation angle when the load is large in the first embodiment.

Fig. 8 is a graph showing changes in current, voltage, and rotation angle when the load is small in the first embodiment.

Fig. 9 is a front view showing an electronic timepiece of the second embodiment.

Fig. 10 is a configuration diagram showing the configuration of an IC of an electronic timepiece according to a second embodiment.

Fig. 11 is a flowchart for explaining the motor control process according to the second embodiment.

Fig. 12 is a flowchart illustrating the load determination process according to the second embodiment.

Fig. 13 is a flowchart for explaining the motor control process according to the second embodiment.

Fig. 14 is a flowchart for explaining Imax setting processing in the second embodiment.

Fig. 15 is a graph showing changes in current, voltage, and rotation angle in the modification example.

Detailed Description

An electronic timepiece 1 according to a first embodiment of the present invention is explained below with reference to the drawings.

As shown in fig. 1, the electronic timepiece 1 is a wristwatch that is worn on the wrist of a user, and includes an outer case 2, a disc-shaped dial 3, a movement not shown, and a second hand 5, a minute hand 6, an hour hand 7, a crown 8, and a button 9 as operating members, which are hands driven by a motor 13 provided in the movement, as shown in fig. 2.

Circuit structure of electronic timepiece

As shown in fig. 2, the electronic timepiece 1 includes a crystal oscillator 11 as a signal source, a battery 12 as a power source, a switch S1 turned on and off in conjunction with the operation of the push button 9, a switch S2 turned on and off in conjunction with the pulling operation of the crown 8, a motor 13, and an IC20 for the timepiece.

The motor 13 is a two-pole single-phase stepping motor used for an electronic timepiece, and is driven by a drive current output from output terminals O1 and O2 of the IC20, as will be described later.

The second hand 5, minute hand 6, and hour hand 7 are linked by a gear train not shown in the figure, and are driven by the motor 13 to display the second, minute, and hour. In the present embodiment, the second hand 5, the minute hand 6, and the hour hand 7 are driven by one motor 13, but for example, a plurality of motors may be provided so as to drive the second hand 5 and the minute hand 6 and the hour hand 7.

As shown in fig. 2, the IC20 includes connection terminals OSC1 and OSC2 to which the crystal oscillator 11 is connected, input/output terminals P1 and P2 to which switches S1 and S2 are connected, power supply terminals VDD and VSS to which the battery 12 is connected, and output terminals O1 and O2 to which the coil 130 of the motor 13 is connected.

In the present embodiment, the positive electrode of the battery 12 is connected to the high-potential power supply terminal VDD, the negative electrode is connected to the low-potential power supply terminal VSS, and the low-potential power supply terminal VSS is grounded.

The crystal oscillator 11 is driven by an oscillation circuit 21 described later to generate an oscillation signal.

The battery 12 is constituted by a primary battery or a secondary battery. In the case of a secondary battery, the secondary battery is charged by a solar cell or the like, which is not shown.

The switch S1 is input in conjunction with the push button 9 located at the two o' clock position of the electronic timepiece 1, and is turned on when the push button 9 is pressed, and turned off when the push button 9 is not pressed, for example.

Switch S2 is a slide switch interlocked with the pulling out of crown 8. In the present embodiment, the crown 8 is in the on state when pulled out to the first stage, and is in the off state when pulled out to the zeroth stage.

Circuit structure of IC

As shown in fig. 3, IC20 includes: an oscillation circuit 21, a frequency dividing circuit 22, a CPU23 for controlling the electronic timepiece 1, a ROM24, an input/output circuit 26, a bus 27, and a motor control circuit 30. CPU is short for Central Processing Unit (CPU), and ROM is short for Read Only Memory (ROM).

The oscillation circuit 21 oscillates the crystal oscillator 11 as a reference signal source at a high frequency, and outputs an oscillation signal of a predetermined frequency generated by the high frequency oscillation to the frequency dividing circuit 22.

The frequency dividing circuit 22 divides the output of the oscillation circuit 21, thereby supplying a timing signal, i.e., a clock signal, to the CPU 23.

The ROM24 stores various programs executed by the CPU 23. In the present embodiment, the ROM24 stores programs for realizing a basic clock function and the like.

The CPU23 executes programs stored in the ROM24, thereby realizing the respective functions.

The input/output circuit 26 outputs the states of the input/output terminals P1 and P2 to the bus 27. The bus 27 is used for data transfer and the like between the CPU23, the input-output circuit 26, the motor control circuit 30, and the like.

The motor control circuit 30 controls the driving of the motor 13 by supplying a driving current to the coil 130 of the motor 13 in accordance with a command input from the CPU23 through the bus 27.

Structure of motor control circuit

As shown in fig. 4, the motor control circuit 30 includes: a decoder 31, a driver 51, and a current detection circuit 61 as a current detection section.

The decoder 31 outputs gate signals P1, P2, N1, N2, N3, and N4 to the driver 51 as described later based on a command input from the CPU 23.

The driver 51 includes two Pch transistors 52 and 53, four Nch transistors 54, 55, 56 and 57, and two detection resistors 58 and 59. The transistors 52 to 57 are controlled by gate signals P1, P2, N1, N2, N3, and N4 output from the decoder 31, and supply currents in both forward and reverse directions to the coil 130 of the motor 13. Therefore, the driver 51 is a driving unit that outputs a driving current to the coil 130 of the motor 13 to drive the motor 13.

The current detection circuit 61 includes: a first reference voltage generating circuit 62, a second reference voltage generating circuit 63, comparators 641, 642, 651, 652 and complex gates 68, 69. The composite gate 68 is one element having the same function as a circuit in which the AND circuits 661 AND 662 AND the OR circuit 680 shown in fig. 4 are combined. The composite gate 69 is one element having the same function as a circuit in which the AND circuits 671 AND 672 AND the OR circuit 690 are combined.

The comparators 641 and 642 compare the voltages generated at both ends of the detection resistors 58 and 59 of the resistance values R1 and R2 with the voltage of the first reference voltage generation circuit 62, respectively.

Since the drive polarity signal PL output from the decoder 31 is inverted AND input to the AND circuit 661 AND the drive polarity signal PL is directly input to the AND circuit 662, the output of one of the comparators 641 AND 642 selected in accordance with the drive polarity signal PL is output as the detection signal DT 1.

The comparators 651 and 652 compare the voltages generated at both ends of the detection resistors 58 and 59 of the resistance values R1 and R2 with the voltage of the second reference voltage generation circuit 63, respectively.

Since the driving polarity signal PL is inverted AND input to the AND circuit 671, AND the driving polarity signal PL is directly input to the AND circuit 672, the output of one of the comparators 651 AND 652 selected in accordance with the driving polarity signal PL is output as the detection signal DT 2.

The first reference voltage generation circuit 62 is set to output a potential corresponding to a voltage generated at both ends of the detection resistors 58 and 59 when the current flowing through the coil 130 is the lower limit current threshold Imin.

Therefore, when the current I flowing through the coil 130 is equal to or greater than the lower limit current threshold Imin, the voltage generated across the detection resistors 58 and 59 exceeds the output voltage of the first reference voltage generation circuit 62, and therefore the detection signal DT1 becomes H level. On the other hand, when the current I is lower than the lower limit current threshold Imin, the detection signal DT1 becomes L level. Therefore, the first reference voltage generation circuit 62, the comparators 641 and 642, and the composite gate 68 of the current detection circuit 61 are a lower limit current detection unit that detects that the current I flowing to the coil 130 is smaller than the lower limit current threshold Imin, and the detection signal DT1 is the detection result of the lower limit current detection unit.

The second reference voltage generation circuit 63 generates a voltage corresponding to the upper limit current threshold value Imax. Therefore, the detection signal DT2 of the current detection circuit 61 is at the H level when the current I flowing through the coil 130 exceeds the upper limit current threshold value Imax, and at the L level when the current I is equal to or less than the upper limit current threshold value Imax. Therefore, the second reference voltage generation circuit 63, the comparators 651 and 652, and the composite gate 69 of the current detection circuit 61 are an upper limit current detection unit that detects that the current I flowing through the coil 130 exceeds the upper limit current threshold Imax, and the detection signal DT2 is the detection result of the upper limit current detection unit.

Control processing of motor control circuit

Next, the control performed by the motor control circuit 30 of the present embodiment will be described with reference to the flowcharts of fig. 5 and 6 and the graphs of fig. 7 and 8. In addition, hereinafter, control in the case where the motor control circuit 30 drives the motor 13 at a frequency of 1Hz, that is, in the case where one step is driven every one second will be exemplified and explained.

When the control of driving the motor 13 at a frequency of 1Hz, that is, driving one step per second is started, the CPU23 of the IC20 executes the processing of step S1 for performing the initial setting, and sets Imax to B, n to 0, and TonX to 0. Here, Imax is a variable indicating any one of three levels, i.e., A, B, C, where the level of the upper limit current threshold Imax is. n is a variable indicating the number of times the driver 51 is turned on from the start of drive control until polarity switching. TonX is a variable set to a predetermined value when the on time Ton, which is the duration of turning on the driver 51, exceeds a predetermined threshold value.

Next, the CPU23 executes step S2, turns on the driver 51, and increments the variable n by 1. That is, when a command to turn on the driver 51 is output from the CPU23 to the decoder 31, the decoder 31 turns on the driver 51 of the motor 13 in accordance with the gate signals P1, P2, N1, N2, N3, and N4. Thus, a forward drive current flows in the coil 130 of the motor 13. In the flowchart and the following description, the term "turning on the driver 51" means that the driver 51 is controlled to be in an on state in which the drive current can be caused to flow through the coil 130, and the term "turning off the driver 51" means that the driver 51 is controlled to be in an off state in which the drive current cannot be caused to flow through the coil 130.

In the present embodiment, the drive current supplied to the coil 130 is switched between a first polarity in which a positive current flows to the coil 130 and a second polarity in which a negative current opposite to the positive current flows.

In this embodiment, the transistors 52 and 57 are controlled to be on, the transistors 53, 54, 55, and 56 are controlled to be off, and the current flowing through the transistor 52, the terminal O1, the coil 130, the terminal O2, the detection resistor 59, and the transistor 57, that is, the current flowing from the terminal O1 to the terminal O2 through the coil 130 is a forward current. The transistors 53 and 56 are controlled to be on, the transistors 52, 54, 55, and 57 are controlled to be off, and the current flowing through the transistor 53, the terminal O2, the coil 130, the terminal O1, the detection resistor 58, and the transistor 56, that is, the current flowing through the coil 130 from the terminal O2 to the terminal O1 is set to be a negative current.

Next, the CPU23 executes step S3 to determine whether or not a predetermined time t1 has elapsed since the driver 51 became on. The predetermined time t1 is a time set as the minimum time of the on time Ton of the driver 51, and the on time Ton of the driver 51 is controlled so as to be equal to or longer than the predetermined time t 1.

If the CPU23 determines no in step S3, the process of step S3 is repeatedly executed.

If the CPU23 determines yes in step S3, the CPU performs the process of step S4 of determining whether or not the current I flowing through the coil 130 exceeds the upper limit current threshold Imax. As described above, when the voltages generated at the detection resistors 58, 59 exceed the reference voltage of the second reference voltage generation circuit 63, the detection signal DT2 of the current detection circuit 61 outputs a signal of H level. Therefore, the CPU23 detects the detection signal DT2 via the decoder 31, and determines no in step S4 when the detection signal DT2 is at the L level, and determines yes in step S4 when the detection signal DT2 changes to the H level.

If the CPU23 determines yes in step S4, the CPU performs the process of step S5 of determining whether n > 1. If the CPU23 determines no in step S5, that is, if n is 1 and the number of times the driver 51 is turned on is the first time, the CPU performs step S6 of turning off the driver 51 via the decoder 31.

On the other hand, in the case where the CPU23 determines yes in step S5, that is, in the case where n is 2 or more, the load determination process S20 is executed each time the driver 51 is turned on. The load determination processing S20 is limited to the case where n is 2 or more because it takes time until the current I reaches the upper limit current threshold value Imax at the time of the first on control of the driver 51 after the start of the drive control of the motor 13 or after the polarity switching, and the on time Ton cannot be used for the load determination.

When executing the load determination process S20, the CPU23 executes step S21 of determining whether or not the variable TonX is "2", as shown in fig. 6. If the CPU23 determines yes in step S21, it maintains the variable TonX at "2" and directly ends the load determination process S20.

The CPU23 executes step S22 of comparing the on-time Ton of the driver 51 with the threshold Ton2 in the case where it is determined no in step S21. If the CPU23 determines yes in step S22, it executes step S23 in which the variable TonX is set to "2", and ends the load determination process S20.

The CPU23 executes step S24 of comparing the on-time Ton of the driver 51 with the threshold Ton1 in the case where it is determined no in step S22. The threshold Ton1 is a time shorter than the threshold Ton 2. If the CPU23 determines yes in step S24, it executes step S25 of setting the variable TonX to "1" and ends the load determination process S20.

If the CPU23 determines no in step S24, the variable TonX is maintained. As described later, the variable TonX is initialized to "0" when switching the polarity.

Therefore, in the load determination process S20, when the on time Ton does not exceed the threshold Ton1 once in the period before switching the polarity, the variable TonX is maintained at "0", and when the on time Ton does not exceed the threshold Ton2 once even if it exceeds the threshold Ton1 once, the variable TonX is maintained at "1". Note that, in a period before switching the polarity, when the on-time Ton exceeds the threshold Ton2 once, the variable TonX is maintained at "2".

The CPU23 executes step S6 of turning off the driver 51 in a case where the determination process of the load determination process S20 is ended, or when the determination in step S5 is no.

The CPU23 issues a command to the decoder 31 to turn off the driver 51 when step S6 is executed, and the decoder 31 turns off the driver 51 by the gate signals P1, P2, N1, N2, N3, N4. Specifically, P1 becomes H level, P2 becomes H level, N1 becomes H level, N2 becomes L level, N3 becomes H level, and N4 becomes H level. Therefore, both ends of the coil 130 are connected to the power supply terminal VSS and short-circuited, and the supply of the current I from the driver 51 to the coil 130 is also stopped. Therefore, the state in which the current does not flow to the coil 130 is a state in which the driver 51 is controlled to be in an off state. In the present embodiment, the Pch transistors 52 and 53 and the Nch transistor 55 are turned on, and the Nch transistors 54, 56, and 57 are turned off, respectively, in the off state of the driver 51 in the first polarity.

Next, the CPU23 executes step S7 of determining whether the current I flowing in the coil 130 is lower than the lower limit current threshold Imin. As described above, when the voltage generated across the detection resistors 58 and 59 is lower than the reference voltage of the first reference voltage generation circuit 62, the detection signal DT1 of the current detection circuit 61 outputs an L-level signal. Therefore, the CPU23 detects the detection signal DT1 via the decoder 31, determines no in step S7 when the detection signal DT1 is at the H level, continues the determination process in step S7, and determines yes in step S7 when the detection signal DT1 changes to the L level.

When the CPU23 determines yes in step S7, it executes step S8 of determining whether or not the off time Toff, which is the duration of turning off the driver 51, exceeds the determination time t2, which is a polarity switching condition. That is, if the off time Toff, which is the elapsed time from turning off the driver 51 until the current I becomes lower than Imin, is equal to or less than the determination time t2, the CPU23 determines no in step S8, and if the determination time t2 is exceeded, determines yes in step S8.

Since the determination of no in step S8 does not satisfy the polarity switching condition, the CPU23 returns to step S2 without performing polarity switching, turns on the driver 51 to drive the motor 13, and increments the variable n by 1.

If the CPU23 determines yes in step S8, the value of the upper limit current threshold Imax is set in accordance with the value of the variable TonX. The upper limit current threshold Imax can be set to A, B, C, which are three levels, in the present embodiment, a is set to the minimum, C is set to the maximum, and B is set to a level between a and C. Namely, A < B < C.

When the load is increased, such as when the weight of the second hand 5, the minute hand 6, and the hour hand 7 driven by the motor 13 is large or when the ambient temperature of the motor 13 is low, the change in the magnetic flux is reduced and the reverse induction voltage is reduced until the time reaches the vicinity of the neutral point where the pulling torque of the stator becomes minimum, for example, until the time reaches the vicinity of 60 degrees, and therefore, the current in the direction of the applied voltage is likely to flow. Thereby, the on time Ton, which is the time until the predetermined upper limit current threshold value Imax is reached, becomes short. Fig. 7 is a diagram showing a correspondence relationship between a current waveform and a rotation angle of the rotor when a load is large.

On the other hand, since the change in magnetic flux becomes abrupt as the load decreases, the reverse induction voltage increases, so that the current in the direction of the applied voltage becomes less likely to flow. This lengthens the on time Ton. Fig. 8 is a diagram showing a correspondence relationship between a current waveform and a rotation angle of the rotor when the load is smaller than the state shown in fig. 7.

As shown in fig. 7, when the load is large, the number of times of turning on the driver 51 before the polarity switching increases, but the on time Ton of each is relatively short. In the case where n is 2 or more, the variable TonX is maintained at "0" when the on-time Ton does not exceed the threshold Ton1 once, that is, when the maximum value of the on-time Ton is less than the threshold Ton 1.

On the other hand, as shown in fig. 8, when the load is small, the number of times of turning on the driver 51 before polarity switching is small, but the on time Ton may become long, and when n is 2 or more, the on time Ton may exceed the threshold Ton2, so the variable TonX is maintained at "2".

Although not shown, the variable TonX is set to "1" when the load is intermediate and the on-time Ton is maintained between the threshold Ton1 and the threshold Ton 2.

Therefore, the CPU23 executes step S9 of determining whether or not the variable TonX is "2", determines that the load is small if yes in step S9, and executes step S10 of setting the value of the upper limit current threshold value Imax to a minimum value a. That is, the CPU23 sets the upper limit current threshold value Imax of the second reference voltage generation circuit 63 to a via the decoder 31.

If no in step S9, the CPU23 executes step S11 of determining whether the variable TonX is "1", and if yes in step S11, determines that the load is moderate, and executes step S12 of setting the upper limit current threshold Imax of the second reference voltage generation circuit 63 to B.

If no in step S11, the variable TonX is "0", and therefore the CPU23 determines that the load is also large, and executes step S13 of setting the upper limit current threshold Imax of the second reference voltage generation circuit 63 to C, which is the maximum.

After setting the value of the upper limit current threshold value Imax in steps S10, S12, and S13, the CPU23 switches the polarity and executes step S14 in which the variable n and the variable TonX are initialized to "0".

Then, the CPU23 executes step S15 of determining whether or not the next motor drive timing is reached, and proceeds to the determination process of step S15 in the case of no in step S15, and returns to step S2 in the case of yes. For example, when the motor 13 is driven every second to move the second hand 5, minute hand 6, and hour hand 7 in steps every second, the CPU23 determines in step S15 that one second has elapsed since the driver 51 was turned on in the previous step S2, determines in step S15 that it is no, and returns to step S2 to execute the next step movement.

Since the polarity is switched in step S2, the CPU23 controls the decoder 31 to output a gate signal set so that the current flowing through the coil 130 is in the opposite direction to the previous one. Specifically, P1 becomes H level, P2 becomes L level, N1, N2, N4 become L level, and N3 becomes H level. Thereby, the Pch transistor 52 is turned off and the Pch transistor 53 is turned on. Further, the Nch transistors 54, 55, and 57 are turned off, and the Nch transistor 56 is turned on. Therefore, a current flows through the Pch transistor 53, the terminal O2, the coil 130, the terminal O1, the detection resistor 58, and the Nch transistor 56. Therefore, the driving current output to the coil 130 has the second polarity, and a negative current, which is opposite to the positive current, flows to the coil 130. Therefore, the state in which the negative current flows to the coil 130 is a state in which the driver 51 is controlled to be in an on state so as to output the driving signal of the second polarity.

Therefore, the CPU23 repeatedly executes steps S2 to S15 and the load determination process S20 while alternately switching the first polarity and the second polarity.

As described above, in the electronic timepiece 1, the CPU23 functions as a driver control unit that controls the driver 51 and a control parameter setting unit that sets a control parameter for controlling the driver 51.

Effect of the first embodiment

The CPU23 as a driver control unit can detect the load of the motor 13 based on a control state, specifically, the on time Ton, in which the driver 51 is controlled to be in the on state or the off state. Therefore, the upper limit current threshold value Imax as a control parameter of the actuator 51 can be adjusted in accordance with the load of the motor 13, that is, the upper limit current threshold value Imax can be maintained or changed, and the motor can be driven under an appropriate driving condition in consideration of the variation in the load of the motor 13. Therefore, the motor 13 can be driven with low power consumption when the load is small, and can be driven with high power consumption when the load is large, so that the motor 13 can be reliably driven with low power consumption.

The CPU23 detects the load of the motor 13 based on the on time Ton while performing drive control while maintaining the drive current of the motor 13 within a fixed range between the upper limit current threshold Imax and the lower limit current threshold Imin, and changes the upper limit current threshold Imax in accordance with the load. Therefore, even if the load of the motor 13 varies, the upper limit current threshold value Imax can be changed according to the load, and therefore the motor 13 can be reliably driven. Further, since the upper limit current threshold value Imax is switched to three levels according to the load, the value of the upper limit current threshold value Imax can be made small even when the load is small, and power consumption can be reduced. That is, the motor 13 can be reliably driven with low power consumption by setting the upper limit current threshold value Imax in accordance with the load.

Further, the time for which the driver 51 is controlled to be in the on state may be measured by the CPU23 or the like, and therefore the on time Ton can be easily measured. Therefore, the CPU23 can easily detect the variation in the load of the motor 13, and can easily control the control parameters.

In the present embodiment, since the load determination process S20 can be executed each time the driver 51 is turned on until the determination of yes in step S8, that is, during the elapsed time Tc during which the polarity is switched, the load variation can be detected with high accuracy.

In the present embodiment, since the CPU23 controls the driver 51 via the bus 27 and the decoder 31, circuit elements can be reduced as compared with the case where the driver 51 is controlled by a logic circuit.

Second embodiment

Next, an electronic timepiece 1A according to a second embodiment will be described with reference to fig. 9 to 14. The same reference numerals are used for members and elements having the same functions as those of the first embodiment, and the description thereof will be omitted.

As shown in fig. 9, an electronic timepiece 1A according to a second embodiment is an electronic timepiece with a chronograph function, and includes an outer case 2, a dial 3, a crown 8, and buttons 9A and 9B. The electronic timepiece 1A has three hand axes coaxially arranged at the center of the plane of the dial 3, and a minute hand 42, an hour hand 43, and an 1/5 chronograph second hand 44 are attached to each of the hand axes. A hand shaft to which a small second hand 41 is attached is arranged in the 10 o' clock direction from the plane center position of the dial 3. A hand shaft to which a minute hand 45 of a chronograph is attached is arranged in a 2 o' clock direction from a plane center position of the dial 3. A hand shaft to which a precision hour hand 46 also serving as a mode hand is attached is arranged in the 6 o' clock direction from the center position of the plane of the dial 3. A date window 3A is opened in the dial 3, and a calendar wheel 47 is provided to be visually recognized from the date window 3A.

As shown in fig. 10, the electronic timepiece 1A includes an IC20A similar to the IC20 of the first embodiment, and further includes first to sixth motor control circuits 30A to 30F.

The first motor control circuit 30A controls driving of a motor, not shown, that drives the small second hand 41, and the second motor control circuit 30B controls driving of a motor, not shown, that drives the minute hand 42 and the hour hand 43. The third motor control circuit 30C controls driving of an unillustrated motor that drives 1/5 the chronograph second hand 44, the fourth motor control circuit 30D controls driving of an unillustrated motor that drives the chronograph minute hand 45, and the fifth motor control circuit 30E controls driving of an unillustrated motor that drives the chronograph hour hand 46. The sixth motor control circuit 30F controls driving of a motor, not shown, that drives the calendar wheel 47.

In the IC20A, P1 is an input/output terminal to which a switch S1 for detecting an input to the pushbutton 9A is connected, P2 is an input/output terminal to which a switch S2 for detecting an input to the pushbutton 9B is connected, and P3 is an input/output terminal to which a switch S3 for detecting an operation of the crown 8 is connected.

Next, a method of controlling the drive of the 1/5 chronograph second hand 44 in the electronic timepiece 1A will be described based on the flowcharts of fig. 11 to 14. 1/5 the chronograph seconds hand 44 is controlled by the CPU23 of the IC20A and the third motor control circuit 30C as in the first embodiment.

When a start signal, which is a motor drive start signal, is input by the start operation of the chronograph function realized by the button 9A, the CPU23 starts the processing of step S40 in fig. 11. Then, the CPU23 first executes step S41, sets the upper limit current threshold value Imax to the initial value Imax0, and sets the variable TonX and the variable m to "0". The initial value Imax0 is a value set in advance by an experiment or the like. The variable TonX is the same as in the first embodiment. The variable m is a flag for controlling whether or not to execute the load determination process S70 or the Imax setting process S80, which will be described later.

Next, the CPU23 executes the same processing as steps S2 to S4 of the first embodiment, i.e., the processing of steps S42 to S44. When the determination in step S44 is yes, the CPU23 executes the determination process in step S45 to determine whether the variable m is "0" and whether the elapsed time from turning on of the driver 51 in step S42 has first elapsed by a preset threshold t 4. After the variable m is initialized to "0" in step S41, as will be described later, the variable m is set to "1" during the execution of Imax setting processing S80, and further set to "0" every minute from the start of the chronograph function. Therefore, in step S45, every minute, it is determined yes when the threshold t4 is first passed from the turn-on driver 51 in step S42.

The threshold t4 is provided so as not to set the on time Ton when the driver 51 is turned on for the first time after switching the polarity as a judgment target, and can be obtained in advance by an experiment or the like. The threshold t4 is set to 0.5ms to 1ms, for example.

In the case of yes in step S45, the CPU23 executes load determination processing S70.

When the load determination process S70 is executed, as shown in fig. 12, the CPU23 executes a step S71 of determining whether the on-time Ton of the driver 51 is longer than the threshold Ton 2.

If the CPU23 determines yes in step S71, it executes step S72 in which the variable TonX is set to "2", and ends the load determination process S70.

If the CPU23 determines no in step S71, the CPU performs step S73 of determining whether the on-time Ton is longer than the threshold Ton 1. If the CPU23 determines yes in step S73, it executes step S74 in which the variable TonX is set to "1", and ends the load determination process S70.

If the CPU23 determines no in step S73, the CPU ends the load determination process S70 by maintaining the initial value "0" without changing the variable TonX.

If the CPU23 determines no in step S45 or ends the load determination process S70, the CPU performs the same processes as in steps S6 to S8 of the first embodiment, i.e., the processes in steps S46 to S48.

If the CPU23 determines no in step S48, the process returns to step S42, and the process of steps S42 to S48 is repeatedly performed. At this time, in the case where the load determination process S70 has been executed, since the first elapsed time is not even if the elapsed time has elapsed the threshold t4, the CPU23 determines no in step S45. That is, as described later, the load determination process S70 is executed once every one minute.

If the CPU23 determines yes in step S48, the CPU performs step S49 of determining whether or not the elapsed time Tc from the start of supply of the drive current until the off-time Toff exceeds the determination time t2 as the polarity switching condition exceeds a preset threshold t 3. The start of supply of the drive current is the first step S42 after step S41 or after the polarity is switched in step S51. The threshold t3 is set to prevent erroneous determination of the rotation determination of the rotor, and when the elapsed time Tc is shorter than the threshold t3, that is, when the elapsed time Tc is extremely short, the motor is highly likely to be inoperative.

Therefore, if the CPU23 determines no in step S49, the CPU performs step S50 of adding a predetermined value dmax to the upper limit current threshold Imax and setting the value as a new upper limit current threshold Imax. The predetermined value dmax is, for example, about 10 to 20% of the upper limit current threshold Imax. When the upper limit current threshold value Imax is increased, the electric power supplied to the coil of the motor is increased, and the possibility of driving the motor is also increased.

After the execution of step S50, the CPU23 returns to step S42 and executes the on control of the driver again.

If the CPU23 determines yes in step S49, the CPU executes step S51 of switching the polarity. The CPU23 executes step S52 of determining whether or not m is 0, and executes Imax setting processing S80 if yes in step S52.

As shown in fig. 14, in the Imax setting process S80, the CPU23 executes a step S81 of determining whether or not the variable TonX is "0", and when it is determined yes in the step S81, determines that the load of the pointer or the like driven by the motor is large, and executes a step S82 of increasing the upper limit current threshold Imax by adding a predetermined value dmax to the upper limit current threshold Imax.

If the CPU23 determines no in step S81, the CPU executes step S83 of determining whether the variable TonX is "1". If yes in step S83, the CPU23 determines that the load on the motor is medium, and executes step S84 of maintaining the upper limit current threshold Imax as Imax.

In the case of no in step S83, that is, in the case where the variable TonX is "2", the CPU23 determines that the load of the motor is small, and executes step S85 of subtracting the predetermined value dmax from the upper limit current threshold Imax to thereby reduce the upper limit current threshold Imax.

The CPU23 executes step S86 in which the variable m is set to "1" after the execution of steps S82, S84, S85. Therefore, the variable m is set to "1" when the setting of the upper limit current threshold value Imax is performed, and is reset to "0" when one minute has elapsed as described later, and is used again as a flag for determining the execution of the load determination processing S70 and the Imax setting processing S80.

The CPU23 ends the Imax setting process S80 after the process of step S86 and returns to the flowchart shown in fig. 13.

If the CPU23 determines no in step S52 or if the processing of Imax setting processing S80 is ended, the CPU determines whether or not the upper limit current threshold Imax is appropriate by the number of times Nonoff of the on state and the off state of the driver 51, and executes the processing of adjusting the upper limit current threshold Imax.

Specifically, the CPU23 executes the step S53 of determining whether or not the number of times nooff of the on-state and off-state, which is obtained by adding the number of times noon of bringing the driver 51 into the on-state and the number of times Noff of bringing the driver into the off-state during the period until the determination in the step S48 is yes, that is, during the elapsed time Tc, is less than the first number of times n 1.

If it is determined yes in step S53, the upper limit current threshold value Imax is large with respect to the load of the motor, and as a result, the detection accuracy of the rotational position of the rotor becomes low, and therefore the CPU23 executes step S54 of reducing the upper limit current threshold value Imax by subtracting the predetermined value dmax from the upper limit current threshold value Imax.

On the other hand, in the case where the CPU23 determines no in step S53, it executes step S55 of determining whether the number Nonoff is greater than the second number n 2. The second order n2 is set to be equal to or greater than the first order n 1. Specific values of the first order number n1 and the second order number n2 can be obtained by performing experiments in advance.

If it is determined yes in step S55, the upper limit current threshold Imax is small with respect to the load of the motor, and as a result, the number of times of the on state and the off state of the driver 51 increases to decrease the driving speed, so the CPU23 executes step S56 of increasing the upper limit current threshold Imax by adding a predetermined value dmax to the upper limit current threshold Imax.

If the CPU23 determines no in step S55, that is, if the number Nonoff is equal to or greater than the first number n1 and equal to or less than the second number n2, it determines that the upper limit current threshold Imax is an appropriate value and maintains the value.

Next, the CPU23 executes step S57 of determining whether the button 9A is input again and a termination signal as a stop signal is input.

If the CPU23 determines no in step S57, that is, if the termination signal is not input, the CPU23 executes step S58 of determining whether or not one minute has elapsed since the last variable m was initialized to "0".

The CPU23 executes step S59 of initializing the variable m and the variable TonX to "0" when it is determined yes in step S58, and maintains the values of the variable m and the variable TonX without initializing them when it is determined no in step S58. Therefore, as described above, in the present embodiment, by executing the load determination processing S70 and the Imax setting processing S80 every minute, even if the load varies while the precision timer operation continues, the load can be determined every minute and the upper limit current threshold Imax can be adjusted according to the load. Although the CPU23 controls the driving of the motor so that one step is executed for each polarity switching, the load determination process S70 is executed during the operation of the first step, and the upper limit current threshold value Imax, which is a control parameter of the second step or later, is set in the Imax setting process S80 in accordance with the on time Ton at the time of the control of the first step. Then, the load determination process S70 is performed at predetermined time intervals, that is, at one minute intervals, and in the steps after the step of performing the load determination process S70, the motor is controlled by the upper limit current threshold value Imax set in the Imax setting process S80.

After the initialization process of step S59 is executed, or in the case of no in step S58, the CPU23 returns to step S42 of fig. 11 and continues the drive process of the motor.

As shown in fig. 13, in the case where the termination signal is input and it is determined yes in step S57, the CPU23 executes step S60 of determining whether or not the reset operation by the button 9B is performed with the input of the switch S2.

If the CPU23 determines yes in step S60, the CPU executes step S61 of performing current control driving to return the pointer to the 0 position. Specifically, the CPU23 can grasp the positions of the 1/5 chronograph second hand 44, chronograph minute hand 45, and chronograph hour hand 46, which are stopped by the input of the end signal, that is, the measurement time, and thus can grasp the number of steps necessary to return the hands 44 to 46 to zero. Therefore, it is only necessary to perform current control driving for moving each pointer by the number of steps until the pointer is moved to the return-to-zero position. Further, since the chronograph hour hand 46 also serves as a mode hand, it may be returned to the mode display without returning to the return-to-zero position.

If the CPU23 determines no in step S60, it executes step S62 of determining whether or not the start operation by the button 9A is performed and the start signal is input.

The CPU23 executes the aforementioned determination process of step S58 if it is determined yes in step S62, executes the initialization process of step S59 if it is determined yes in step S58, returns to step S42 of fig. 11, and restarts the driving of the motor.

If the CPU23 determines no in step S62, it executes step S63 of determining whether or not 60 minutes has elapsed from the start of the chronograph action. If yes in step S63, the user may leave the apparatus for 60 minutes while performing the termination operation. Since the possibility that the user forgets the reset operation is high in this case, the CPU23 executes step S61 to thereby execute the current control driving for zeroing.

If the CPU23 determines no in step S63, the process returns to step S60 to continue the respective processes described above.

Therefore, in the electronic timepiece 1A, the CPU23 functions as an actuator control unit that controls the actuator 51 and a control parameter setting unit that sets a control parameter for controlling the actuator 51.

Effect of the second embodiment

In the second embodiment, as in the first embodiment, while the drive control is performed while the drive current of the motor 13 is maintained within a fixed range between the upper limit current threshold value Imax and the lower limit current threshold value Imin, the load of the motor 13 is detected based on the on time Ton, and the upper limit current threshold value Imax is changed according to the load. Therefore, even if the load of the motor varies, the upper limit current threshold value Imax can be changed according to the load, and therefore the motor 13 can be reliably driven.

Further, the load determination process S70 is executed only once per minute and is controlled by the upper limit current threshold Imax set in the Imax setting process S80 based on the determination result of the load determination process S70 in one minute, so that even in a motor that is driven at a high speed, it is possible to control the motor that drives the 1/5 chronograph second hand 44.

In the Imax setting process S80, the upper limit current threshold Imax is not set to the fixed value A, B, C as in the first embodiment, but the predetermined value dmax is added or subtracted, and therefore, when it is determined in the load determination process S70 per minute that the load is small or large, the predetermined value dmax can be repeatedly added or subtracted, and therefore, the upper limit current threshold Imax can be appropriately adjusted according to the load of the motor. Therefore, the motor can be reliably driven.

The setting of the upper limit current threshold value Imax in the Imax setting process S80 is performed at intervals of one minute, whereas the upper limit current threshold value Imax is adjusted by comparing the number of times Nonoff with the first number of times n1 and the second number of times n2 every time the polarity is switched, so that the upper limit current threshold value Imax can be adjusted even if there is a load variation during the period in which the Imax setting process S80 is performed, and the motor can be reliably driven.

Therefore, the optimum setting can be selected according to various conditions such as the size of the needle attached to the movement, temperature change, and increase in load, and the motor can be reliably driven.

Other embodiments

The present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within a range in which the object of the present invention can be achieved are also included in the present invention.

For example, in the above embodiments, the polarity switching is determined based on the off time Toff, but the polarity switching may be determined based on the on time Ton when the load is low. That is, when it is known that the load during use is lower than the predetermined value, or when it is confirmed that the load is low by the load determination processing S20 or S70, as shown in fig. 15, when it is detected that the on time Ton is equal to or longer than the threshold Ton3, the driver 51 may be turned off to stop the supply of the drive current and the polarity may be switched. Since the on-time Ton is maximized in the vicinity of the neutral point where the pulling torque of the stator is minimized, the threshold Ton3 can be set by an experiment or the like to detect that the rotor has rotated to the vicinity of the neutral point. The neutral point is, for example, around 60 degrees when the rotor rotates from 0 degrees to 180 degrees. If the neutral point is exceeded, the rotor can be rotated by inertia from the point at which the next pulling torque becomes maximum, that is, the starting position, to a position rotated by 180 degrees, even if the drive current is not output. Therefore, the driver 51 can be turned off at an earlier timing than in the case of detection by detecting the off-time Toff of the rotor in the vicinity of 180 degrees, and the power consumption can be further reduced.

Although the on-time Ton is compared with the thresholds Ton1 and Ton2 and the value of the upper limit current threshold Imax as the control parameter is set in each of the above embodiments, the off-time Toff may be compared with the threshold and the value of the upper limit current threshold Imax as the control parameter may be set. That is, as the load of the motor 13 increases, the change in the magnetic flux becomes gentle, the reverse induction voltage decreases, and the current value in the case where no voltage is applied tends to decrease. Particularly after the neutral point, the off time Toff in the current control becomes shorter as compared with the case where the load is small. Conversely, when the load of the motor 13 decreases, the off-time Toff becomes longer. Therefore, instead of the on time Ton, the off time Toff may be compared with a predetermined threshold to estimate the magnitude of the load, and the value of the upper limit current threshold Imax as the control parameter may be set.

Although the upper limit current threshold value Imax is set as the control parameter in each of the above embodiments, the lower limit current threshold value Imin may be set.

As the control parameter, the determination time t2 of the off time Toff for determining polarity switching may be set. For example, the time of the determination time t2 may be set to be long when the load is determined to be large, and the time of the determination time t2 may be set to be short when the load is determined to be small.

The determination time t2 of the upper limit current threshold Imax, the lower limit current threshold Imin, and the off-time Toff as control parameters may be set according to the length of the elapsed time Tc from the start of the supply of the drive current until the off-time Toff exceeds the determination time t2 as the polarity switching condition.

That is, as shown in fig. 7, the elapsed time Tc becomes longer when the load of the motor 13 is large, and as shown in fig. 8, the elapsed time Tc becomes shorter when the load of the motor 13 is small. Therefore, the elapsed time Tc until the polarity switching is compared with the predetermined value Tc1, and if Tc ≧ Tc1, the load is large, and therefore, for example, the upper limit current threshold Imax is increased, and if Tc < Tc1, the load is small, and therefore, for example, the upper limit current threshold Imax is decreased.

Further, the elapsed time Tc may be compared with two predetermined values Tc1, Tc2, and the upper limit current threshold Imax may be set to three levels. For example, when Tc1 < Tc2, Imax may be C if Tc < Tc1, B if Tc1 ≦ Tc < Tc2, and a when Tc ≧ Tc 2.

Although the upper limit current threshold value Imax is adjusted according to the value of the count nooff in addition to the setting of the upper limit current threshold value Imax in the Imax setting process S80 in the second embodiment, the adjustment may be performed only by the Imax setting process S80 without performing the adjustment according to the count nooff.

In the second embodiment, the upper limit current threshold value Imax is adjusted based on the number of times nooff of the on state and the off state obtained by adding the number of times Non that the driver 51 is brought into the on state and the number of times Noff that the driver 51 is brought into the off state. However, the upper limit current threshold value Imax may be adjusted by comparing any one of the number of times Non of on state and the number of times Noff of off state with a predetermined threshold value.

In the above embodiments, the current I flowing through the coil 130 is compared with the upper limit current threshold value Imax and the lower limit current threshold value Imin to control the on state or the off state of the driver, but the present invention is not limited thereto. For example, only the upper limit current threshold value Imax may be set, and after the current I exceeds the upper limit current threshold value Imax and the driver is turned off, the driver may be controlled to be turned on at a time point when a predetermined time has elapsed. In this case, since the off-time Toff is constant for a predetermined time, the load variation may be determined by a parameter other than the off-time Toff, for example, the on-time Ton.

Further, only the lower limit current threshold Imin may be set, and after the current I is lower than the lower limit current threshold Imin and the driver is turned on, the driver may be controlled to be turned off at a time point when a predetermined time has elapsed. In this case, the on-time Ton is fixed for a predetermined time, and therefore the load variation can be determined by a parameter other than the on-time Ton, for example, the off-time Toff.

Although the driver 51 is controlled by the CPU23 in the above embodiments, the driver 51 may be controlled by a logic circuit. If the driver control unit is configured by a logic circuit, power consumption can be reduced as compared with the case where the driver control unit is configured by the CPU 23. The CPU23 may be constituted by one IC or a plurality of ICs.

Description of the symbols

1. 1a … electronic timepiece; 5 … second hand; 6 … minute; 7 hour hand 7 …; 8 … crown; 9 … push buttons; 9a … button; 9B … button; 11 … crystal oscillator; 12 … batteries; 13 … a motor; 130 … coil; 21 … oscillating circuit; 22 … frequency divider circuit; 23 … CPU; 24 … ROM; 26 … input-output circuit; 27 … bus; 30 … motor control circuit; 30a … first motor control circuit; 30B … second motor control circuit; 30C … third motor control circuit; 30D … fourth motor control circuit; 30E … fifth motor control circuit; 30F … sixth motor control circuit; a 31 … decoder; 41 … small second hand; 42 … minute hand; 43 … hour hand; 44 … 1/5 chronograph second hand; 45 … precision timing minute hand; 46 … precision hour hand; 47 … calendar wheel; 61 … current detection circuit; 62 … a first reference voltage generating circuit; 63 … second reference voltage generating circuit.