Electronic timepiece and control method of electronic timepiece

Abstract

An electronic clock and its control method. The polarity of a stepper motor can be determined without moving the hands. The electronic clock includes: a hand; a stepper motor with a coil that drives the hand; a drive circuit that drives the stepper motor; a control unit that controls the drive circuit; a current detection circuit that detects the current flowing through the drive circuit; and a storage unit that stores the polarity information of the drive pulses output from the control unit to the drive circuit. When the storage unit is initialized, the control unit initializes the polarity information stored in the storage unit, and outputs a polarity detection pulse to the drive circuit indicating that the stepper motor has not rotated one step, based on the initialized polarity information. Based on the current value detected by the current detection circuit corresponding to the output of the polarity detection pulse, a polarity discrimination process is performed to determine whether the polarity of the stepper motor matches the polarity information; if they do not match, the polarity information is changed.

Description

Technical Field

[0001] This invention relates to electronic clocks and watches, and methods for controlling electronic clocks and watches. Background Technology

[0002] Patent Document 1 discloses an electronic clock that, during system reset such as when the hands are installed or the battery is connected, performs a hand position detection operation to simultaneously move the hands in the forward direction and detect whether the hands are at a reference position, after causing the hands to move in the reverse direction. This shortens the hand position detection processing time after system reset. Before moving the hands in the reverse direction, the electronic clock outputs two forward-direction drive pulses for rotor polarity matching. By outputting two forward-direction drive pulses, if the rotor polarity is mismatched, the hands are driven in one step; if the polarity is matched, the hands are driven in two steps, thus ensuring that the rotor polarity and the polarity of the drive pulses are matched.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2021-113782

[0004] In the electronic clock described in Patent Document 1, two forward-direction drive pulses are output during system reset to match the rotor's polarity. Therefore, assuming the pointer is at a reference position, its position shifts due to polarity matching. This necessitates a time-consuming process: after moving the pointer a certain number of steps in the reverse direction, it is moved in the forward direction to check if the reference position has been reached. Therefore, it is desirable to eliminate the output of the drive pulses for polarity matching, i.e., to determine the rotor's polarity without moving the pointer. Summary of the Invention

[0005] The electronic clock of the present invention is characterized by comprising: a pointer; a stepper motor having a coil and driving the pointer; a drive circuit driving the stepper motor; a control unit controlling the drive circuit; a current detection circuit detecting the current value flowing through the drive circuit; and a storage unit storing polarity information of drive pulses output from the control unit to the drive circuit. When the storage unit is initialized, the control unit initializes the polarity information stored in the storage unit, outputs a polarity detection pulse indicating that the stepper motor has not rotated one step to the drive circuit according to the initialized polarity information, and performs polarity discrimination processing to determine whether the polarity of the stepper motor is consistent with the polarity information based on the current value detected by the current detection circuit in accordance with the output of the polarity detection pulse. If they are inconsistent, the polarity information is changed.

[0006] The electronic clock of the present invention is characterized by comprising: a pointer; a stepper motor having a coil and driving the pointer; a drive circuit driving the stepper motor; a control unit controlling the drive circuit; a current detection circuit detecting the current value flowing through the drive circuit; and a storage unit storing polarity information of drive pulses output from the control unit to the drive circuit. The control unit outputs a polarity detection pulse to the drive circuit based on the polarity information stored in the storage unit, indicating that the stepper motor has not rotated one step. The current detection circuit detects the current value in the output of the polarity detection pulse. The control unit measures the elapsed time from the start of outputting the polarity detection pulse. If the elapsed time until the current value is detected to exceed a predetermined value is within a predetermined time, it determines that the polarity of the stepper motor is consistent with the polarity information. If the elapsed time exceeds the predetermined time, it determines that the polarity of the stepper motor is inconsistent with the polarity information. In the case of inconsistency, the polarity information is changed.

[0007] The control method for an electronic clock of the present invention is characterized in that the electronic clock has: a pointer; a stepper motor having a coil and driving the pointer; a drive circuit driving the stepper motor; a current detection circuit detecting the current value flowing through the drive circuit; and a storage unit storing polarity information of drive pulses output to the drive circuit. When the storage unit is initialized, the polarity information stored in the storage unit is initialized. Based on the initialized polarity information, a polarity detection pulse indicating that the stepper motor has not rotated one step is output to the drive circuit. Based on the current value detected by the current detection circuit corresponding to the output of the polarity detection pulse, polarity discrimination processing is performed to determine whether the polarity of the stepper motor is consistent with the polarity information. If they are inconsistent, the polarity information is changed.

[0008] The control method for an electronic clock of the present invention is characterized in that the electronic clock has: a pointer; a stepper motor having a coil and driving the pointer; a drive circuit driving the stepper motor; a current detection circuit detecting the current value flowing through the drive circuit; and a storage unit storing polarity information of drive pulses output to the drive circuit. Based on the polarity information stored in the storage unit, the drive circuit outputs a polarity detection pulse indicating that the stepper motor has not rotated one step. The current detection circuit detects the current value during the output of the polarity detection pulse, measures the elapsed time from the start of outputting the polarity detection pulse, and determines that the polarity of the stepper motor is consistent with the polarity information if the elapsed time until the current value is detected to exceed a predetermined value is within a predetermined time. If the elapsed time exceeds the predetermined time, the polarity of the stepper motor is determined to be inconsistent with the polarity information, and the polarity information is changed if there is inconsistency. Attached Figure Description

[0009] Figure 1 This is a front view showing the electronic clock of the first embodiment.

[0010] Figure 2 This is a circuit diagram showing the circuit structure of the electronic clock according to the first embodiment.

[0011] Figure 3 This is a diagram showing the structure of the first motor of the electronic clock according to the first embodiment.

[0012] Figure 4 This is a structural diagram showing the structure of the IC of the electronic clock of the first embodiment.

[0013] Figure 5 This is a circuit diagram showing the structure of the first motor control circuit according to the first embodiment.

[0014] Figure 6 This is a flowchart illustrating the polarity detection process of the first embodiment.

[0015] Figure 7 This is a diagram showing the current waveform flowing through the drive circuit when the polarities are consistent in the first embodiment.

[0016] Figure 8 This is a diagram showing the current waveform flowing through the drive circuit when the polarity is inconsistent in the first embodiment.

[0017] Figure 9 This is a flowchart illustrating the polarity detection process of the second embodiment.

[0018] Figure 10 This is a diagram showing the current waveform flowing through the drive circuit when the polarities are consistent in the second embodiment.

[0019] Figure 11 This is a diagram showing the current waveform flowing through the drive circuit when the polarity is inconsistent in the second embodiment.

[0020] Figure 12 This is a flowchart illustrating the polarity detection process of the third embodiment.

[0021] Figure 13 This is a flowchart illustrating another example of the polarity detection process in the third embodiment.

[0022] Figure 14 This is a circuit diagram showing the circuit structure of the electronic clock according to the fourth embodiment.

[0023] Figure 15 This is a flowchart illustrating the control process of the fourth embodiment.

[0024] Label Explanation

[0025] 1. Electronic clock; 1B Electronic clock; 3. Second hand; 4. Minute hand; 5. Hour hand; 10. Movement; 10B Movement; 11. Quartz oscillator; 12. Battery; 13. First motor; 14. Second motor; 20IC; 20B IC; 23. CPU; 24. ROM; 25. RAM; 30A First motor control circuit; 30B Second motor control circuit; 31. Decoder; 50. Driver; 60. Current detection circuit; 62. First reference voltage generation circuit; 63. Second reference voltage generation circuit; 130. Coil; 131. Stator; 133. Rotor. Detailed Implementation

[0026] [First Implementation]

[0027] Hereinafter, the electronic clock 1 of the first embodiment will be described with reference to the accompanying drawings. Figure 1 This is a front view showing electronic clock 1. Electronic clock 1 is a timepiece with functions such as a stopwatch.

[0028] like Figure 1 As shown, the electronic clock 1 has a round dial 2, a second hand 3, a minute hand 4, an hour hand 5, a crown 6, a button A 7, and a button B 8.

[0029] [Circuit structure of electronic clocks]

[0030] Figure 2 This is a diagram showing the circuit structure of electronic clock 1.

[0031] like Figure 2 As shown, the electronic clock 1 has a movement 10 that drives the second hand 3, minute hand 4 and hour hand 5 as pointers.

[0032] The movement 10 is configured to include a quartz oscillator 11 as a signal source, a battery 12 as a power source, switches SW1 to SW3, a first motor 13, a second motor 14, and an IC 20 for clocks.

[0033] Switch SW1 and Figure 1 The table shown indicates that the operation of switch 6 is linked to its pull-out action. Switch SW2 is linked to the operation of button A 7. Switch SW3 is linked to the operation of button B 8.

[0034] Motor 13 is a stepper motor that drives the second hand 3, and motor 14 is a stepper motor that drives the minute hand 4 and the hour hand 5. IC is also an abbreviation for Integrated Circuit.

[0035] IC20 includes connection terminals OSC1 and OSC2 for connecting to the quartz oscillator 11, input / output terminals G1 and G3 for connecting to switches SW1 to SW3, power terminals VDD and VSS for connecting to the battery 12, output terminals O1 and O2 for connecting to the first motor 13, and output terminals O3 and O4 for connecting to the second motor 14.

[0036] In addition, in this embodiment, the positive electrode of battery 12 is connected to the power terminal VDD on the high potential side, the negative electrode of battery 12 is connected to the power terminal VSS on the low potential side, and the power terminal VSS on the low potential side is set as the reference potential.

[0037] Battery 12 is composed of a primary battery or a secondary battery. In the case of a secondary battery, it is charged by a power generation device such as a solar cell (not shown in the figure).

[0038] Figure 3 This is a diagram showing the structure of the first motor 13. Furthermore, although the description is omitted, the second motor 14 has the same structure as the first motor 13.

[0039] like Figure 3 As shown, the first motor 13 includes a stator 131, a coil 130, and a rotor 133. The two ends of the coil 130 are connected to the output terminals O1 and O2 of the IC 20. Furthermore, the rotor 133 is a magnet with two radial poles. Therefore, the first motor 13 is a two-pole single-phase stepper motor for electronic clocks, driven by a drive current supplied from the output terminals O1 and O2 of the IC 20.

[0040] For example, when a drive current flows through the coil 130 from the output terminal O1 to the output terminal O2, Figure 3 A counterclockwise magnetic field is generated. This magnetic field polarizes the stator 131, thereby repelling the rotor 133 and causing the rotor 133 to rotate by a unit amount, i.e., 180°. When the rotor 133 has rotated 180°, a drive current flows from the output terminal O2 to the output terminal O1. Thus, in Figure 3A clockwise magnetic field is generated. This magnetic field causes the stator 131 to be polarized in the opposite direction to its previous polarization, thereby repelling the rotor 133 and causing the rotor 133 to rotate further by 180°. By repeating this action, the rotor 133 continues to rotate. Thus, switching the output terminals O1 and O2 that supply the drive current to switch the direction of the drive current flow each time the rotor 133 rotates by a unit amount is equivalent to switching the polarity of the drive current. In this embodiment, the IC20 rotates the rotor 133 by the desired amount of rotation by alternately and repeatedly switching the first polarity of the drive current flowing from output terminal O1 to output terminal O2 and the second polarity of the drive current flowing from output terminal O2 to output terminal O1. Furthermore, in this specification, the posture of the rotor 133, which can be expressed in angles from 0 to 360°, is called the "rotation angle," and the cumulative rotation angle when repeated by a unit amount of rotation is called the "rotation amount."

[0041] Similarly, the second motor 14 is driven by the drive current supplied to the output terminals O3 and O4 of IC20.

[0042] [IC Circuit Structure]

[0043] Figure 4 This is a structural diagram showing the structure of IC20.

[0044] like Figure 4 As shown, IC20 includes an oscillation circuit 21, a frequency divider circuit 22, a control unit for the electronic clock 1 (CPU 23), ROM 24, RAM 25, an input circuit 26, a bus 27, a first motor control circuit 30A, and a second motor control circuit 30B. Furthermore, the first motor control circuit 30A and the second motor control circuit 30B are examples of motor control circuits. CPU is an abbreviation for Central Processing Unit, ROM is an abbreviation for Read Only Memory, and RAM is an abbreviation for Random Access Memory.

[0045] The oscillating circuit 21 makes it act as Figure 2 The quartz oscillator 11 of the reference signal source shown oscillates at a high frequency, and the oscillation signal of the specified frequency (32768Hz) generated by the high-frequency oscillation is output to the frequency divider circuit 22.

[0046] Frequency divider circuit 22 divides the output of oscillation circuit 21 to provide timing signal or 1Hz reference signal to CPU 23.

[0047] ROM24 stores various programs executed by CPU 23. In this embodiment, in addition to programs for implementing timing functions, stopwatch functions, etc., ROM24 also stores a program for implementing a polarity detection function that detects the polarity of the stepper motor after reset.

[0048] The CPU 23 executes the program stored in the ROM 24 to implement the above functions. That is, the CPU 23 implements the following functions: timing function, which counts the reference signal provided by the frequency divider circuit 22 to keep track of the current time or the elapsed time during stopwatch operation; drive control function, which controls the stepper motor to move the pointer according to the time being counted; and polarity detection function, which detects the polarity of the stepper motor.

[0049] Input circuit 26 outputs the status of input / output terminals G1 to G3 to BUS 27. BUS 27 is used for data transmission between CPU 23, input circuit 26, first motor control circuit 30A, and second motor control circuit 30B.

[0050] The first motor control circuit 30A and the second motor control circuit 30B supply a predetermined drive current to the coils 130 of the first motor 13 and the second motor 14 via drive pulses input from the CPU 23 through the BUS 27. At this time, the CPU 23 outputs drive pulses to the first motor control circuit 30A and the second motor control circuit 30B corresponding to the polarity information stored in the RAM 25. Therefore, the RAM 25 is a storage unit that stores the polarity information of the drive pulses output to the first motor control circuit 30A and the second motor control circuit 30B, i.e., the first polarity or the second polarity. Whenever the CPU 23 outputs a drive pulse, the polarity information stored in the RAM 25 alternately changes to the first polarity and the second polarity.

[0051] Furthermore, when RAM25 is initialized via system reset or similar means, CPU23 also initializes the polarity information stored in RAM25. In this embodiment, when RAM25 is initialized, CPU23 stores the first polarity as the initial value of the polarity information in RAM25.

[0052] [Structure of motor control circuit]

[0053] The first motor control circuit 30A controls the first motor 13 so that the second hand 3 can move in both forward and reverse directions, i.e., clockwise and counterclockwise. Therefore, the first motor control circuit 30A only needs to be able to drive the first motor 13 in both forward and reverse directions.

[0054] Similarly, the second motor control circuit 30B controls the second motor 14 so that the minute hand 4 and the hour hand 5 can move in both directions.

[0055] Figure 5 This is a circuit diagram showing the structure of the first motor control circuit 30A. Furthermore, the structure of the second motor control circuit 30B is the same as that of the first motor control circuit 30A; therefore, its description is omitted.

[0056] The first motor control circuit 30A includes a decoder 31, a driver 50, and a current detection circuit 60.

[0057] The decoder 31 outputs control signals to the driver 50 based on the drive pulses output from the CPU 23. Specifically, drive pulses of either the first or second polarity output from the CPU 23 are input to the decoder 31 via the BUS 27. The decoder 31 outputs gate signals P1, P2, N1, N2, N3, and N4 as control signals to the driver 50 according to the polarity of the input drive pulse. That is, when a drive pulse of the first polarity is input, the decoder 31 outputs a control signal that is set to allow drive current to flow from output terminal O1 to output terminal O2 relative to the coil 130; when a drive pulse of the second polarity is input, the decoder outputs a control signal that is set to allow drive current to flow from output terminal O2 to output terminal O1 relative to the coil 130. Therefore, the CPU 23, BUS 27, and decoder 31 constitute the driver control unit that controls the driver 50.

[0058] The driver 50 is a drive circuit that supplies current to the coil 130 of the first motor 13 to drive the stepper motor. The driver 50 has two Pch transistors 52 and 53, four Nch transistors 54, 55, 56, and 57, and two sense resistors 58 and 59. Each transistor 52 to 57 is controlled by a control signal output from the decoder 31 to supply current I in both positive and negative directions to the coil 130 of the first motor 13.

[0059] The current detection circuit 60 includes a first reference voltage generation circuit 62, a second reference voltage generation circuit 63, comparators 641, 642, 651, and 652, and compound gates 68 and 69. Compound gate 68 is a component that functions equivalently to a circuit formed by combining AND circuits 661 and 662 and OR circuit 680. Compound gate 69 is a component that functions equivalently to a circuit formed by combining AND circuits 671 and 672 and OR circuit 690.

[0060] Comparators 641 and 642 compare the voltage generated across the coil 130 with the voltage of the first reference voltage generation circuit 62, respectively.

[0061] The drive polarity signal PL output from decoder 31 is inverted and input to AND circuit 661, and the drive polarity signal PL is directly input to AND circuit 662. Therefore, the output of one of the comparators 641 and 642 selected by the drive polarity signal PL is used as the detection signal DT1 output.

[0062] Comparators 651 and 652 compare the voltage generated across coil 130 with the voltage of the second reference voltage generation circuit 63, respectively.

[0063] The drive polarity signal PL is inverted and input to AND circuit 671, and the drive polarity signal PL is directly input to AND circuit 672. Therefore, the output of one of the comparators 651 and 652 selected by the drive polarity signal PL is used as the detection signal DT2 output.

[0064] The first reference voltage generation circuit 62 selectively generates a voltage equivalent to the lower limit target current value Imin and a voltage equivalent to the polarity discrimination current value Ith. The polarity discrimination current value Ith is a current value smaller than the lower limit target current value Imin.

[0065] During polarity determination, the CPU23 inputs a selection signal to the first reference voltage generation circuit 62 via BUS27 to select the polarity determination current value Ith. The first reference voltage generation circuit 62 outputs a potential equivalent to the voltage generated across the coil 130 when the current I flowing through the coil 130 is the polarity determination current value Ith.

[0066] Additionally, as described later, during the fast forward drive of the motor, a selection signal for selecting the lower limit target current value Imin is input from the CPU 23 to the first reference voltage generation circuit 62 via BUS 27. The first reference voltage generation circuit 62 outputs a potential equivalent to the voltage generated across the coil 130 when the current I flowing through the coil 130 is the lower limit target current value Imin.

[0067] Therefore, when the motor is driven, if the current I flowing through the coil 130 is greater than or equal to the lower limit target current value Imin, the voltage generated across the coil 130 becomes greater than or equal to the output voltage of the first reference voltage generation circuit 62, and thus the detection signal DT1 becomes high level. On the other hand, if the current I is lower than the lower limit target current value Imin, the detection signal DT1 becomes low level. Therefore, the first reference voltage generation circuit 62, comparators 641 and 642, and compound gate 68 of the current detection circuit 60 are configured to detect when the current I flowing through the coil 130 changes from a value greater than the lower limit target current value Imin to a value less than the lower limit target current value Imin.

[0068] Similarly, during polarity discrimination, when the current I flowing through coil 130 is greater than or equal to the polarity discrimination current value Ith, the voltage generated across coil 130 becomes greater than or equal to the output voltage of the first reference voltage generation circuit 62, and therefore, the detection signal DT1 becomes high level. On the other hand, when the current I is lower than the polarity discrimination current value Ith, the detection signal DT1 becomes low level. Therefore, the first reference voltage generation circuit 62, comparators 641 and 642, and compound gate 68 of the current detection circuit 60 are configured such that by selecting the polarity discrimination current value Ith through the first reference voltage generation circuit 62, the current I flowing through coil 130 can be detected when it changes from a value smaller than the polarity discrimination current value Ith to a larger value.

[0069] The second reference voltage generation circuit 63 generates a voltage equivalent to the upper limit target current value Imax. Therefore, the detection signal DT2 of the current detection circuit 60 becomes H level when the current I flowing through the coil 130 exceeds the upper limit target current value Imax, and becomes L level when it is below the upper limit target current value Imax. Thus, the second reference voltage generation circuit 63, comparators 651 and 652, and compound gate 69 of the current detection circuit 60 are configured to detect when the current I flowing through the coil 130 changes from a value smaller than the upper limit target current value Imax to a value larger than the upper limit target current value Imax.

[0070] [Polarity Detection and Processing]

[0071] Next, refer to Figure 6 This section explains the polarity detection process during the system reset of the electronic clock 1. The system reset is performed under the following specified conditions: operator operation of the crown 6, button A 7, and button B 8; input to the system reset terminal exposed by opening the back cover; and battery connection.

[0072] After the system reset is performed, CPU 23 executes step S11 to start the system and initialize the internal data, such as polarity information, stored in RAM 25. Therefore, the information stored in RAM 25 becomes the initial value, i.e., the first polarity.

[0073] Next, CPU23 executes step S12 and begins outputting the first polarity detection pulse after initialization. The polarity detection pulse is the pulse when the rotor 133 has not rotated one step, for example, when the rotation angle of the rotor 133 is less than 45 degrees. That is, the polarity detection pulse sets the pulse width (i.e., the voltage application time) based on the relationship between the resistance value of the coil 130 and the electromotive force, thereby setting a pulse width that does not cause the rotor 133 to rotate one step. For example, in the case of a stepper motor with a coil 130 resistance of 2kΩ, by setting the polarity detection pulse width to 300μsec and the polarity discrimination current value Ith to 0.16mA, the current polarity of the stepper motor can be determined. Furthermore, in the case of a stepper motor with a coil 130 resistance of 500Ω, by setting the polarity detection pulse width to 100μsec and the polarity discrimination current value Ith to 1.6mA, the polarity can be determined.

[0074] Next, CPU23 executes step S13, waiting for a preset current change time. The current change time is set based on the pulse width of the polarity detection pulse, i.e., the polarity detection time. That is, the current change time is slightly shorter than the polarity detection time; for example, when the polarity detection time is 300 μsec, it is set to about 280 μsec, and when the polarity detection time is 100 μsec, it is set to about 90 μsec.

[0075] When the current change time has elapsed since the polarity detection pulse was first output, CPU 23 executes step S14 to detect the current flowing through the driver 50, which serves as the driving circuit, i.e., the current I flowing through the coil 130. Specifically, a voltage equivalent to the polarity discrimination current value Ith is selected as the generation voltage of the first reference voltage generation circuit 62, and it is detected whether the value of the current I flowing through the coil 130 exceeds the polarity discrimination current value Ith.

[0076] Figure 7 This is a graph showing the waveform of current I when the polarity of rotor 133 matches the polarity of the polarity detection pulse. Figure 8 This is a diagram showing the waveform of current I when the polarity of rotor 133 is inconsistent with the polarity of the drive pulse. As described above, CPU 23 outputs a polarity detection pulse of the first polarity, so decoder 31 controls each transistor 52-57, so that output terminal O1 is connected to power supply terminal VDD, and output terminal O2 is connected to power supply terminal VSS, i.e., grounded.

[0077] exist Figure 7 , 8 In this context, V_O1 is the voltage value at output terminal O1, and V_O2 is the voltage value at output terminal O2. For example... Figure 7As shown, when the CPU23 outputs a polarity detection pulse and the voltage V_O1 at the output terminal O1 changes from L(VSS) to H(VDD), current I flows through coil 130. Here, as... Figure 7 As shown, when the polarity of rotor 133 matches the polarity of the polarity detection pulse, rotor 133 repels, thus generating an induced current more quickly. Therefore, at the current detection timing Td after the current change time, the current I exceeds the polarity discrimination current value Ith, and the detection signal DT1 becomes level H. On the other hand, as... Figure 8 As shown, when the polarities are inconsistent, the rotor 133 performs an attraction action, thus generating an induced current more slowly. Therefore, at the current detection timing Td, the current I is less than the polarity discrimination current value Ith, and the detection signal DT1 becomes the L level.

[0078] Therefore, the CPU23 outputs a polarity detection pulse and applies a voltage to the output terminal O1. The level of the detection signal DT1 is used to confirm whether the current I detected at the specified current detection timing Td exceeds the preset specified value, i.e., the polarity discrimination current value Ith. Thus, the polarity of the rotor 133 can be determined.

[0079] After performing the current detection processing in step S14, CPU23 executes step S15, stopping the output of polarity detection pulses when the polarity detection time has elapsed since the start of outputting polarity detection pulses.

[0080] Next, CPU23 executes step S16, and determines whether the detected current value exceeds the polarity discrimination current value Ith based on the level of the detection signal DT1 during current detection in step S14.

[0081] If the CPU23 determines "yes" in step S16, it determines in step S17 that the position (polarity) of the rotor 133 is consistent with the IC control polarity, i.e., the polarity information stored in RAM 25, and ends the polarity detection process. Here, as described above, the polarity detection pulse is the first polarity. Therefore, the current polarity of the rotor 133 is the first polarity. Then, by outputting the first polarity drive pulse, the stepper motor can be driven.

[0082] On the other hand, if the CPU 23 determines "no" in step S16, it determines in step S18 that the position (polarity) of the rotor 133 is inconsistent with the IC control polarity, i.e., the polarity information stored in RAM 25. Therefore, the CPU 23 executes step S19 to change the polarity information stored in RAM 25. That is, the first polarity is stored in RAM 25 as the initial value of the polarity information, so the polarity information in RAM 25 is changed to the second polarity, and the polarity detection process ends.

[0083] By performing the polarity detection process described above, the polarity information for motor control stored in RAM 25, i.e., the IC control polarity, is consistent with the current polarity of the stepper motor rotor 133. Therefore, based on the polarity information stored in RAM 25, drive pulses are output from CPU 23, thereby reliably driving the stepper motor.

[0084] That is, when the CPU23 is normally moving the needle, it outputs a drive pulse with a certain pulse width to the first motor control circuit 30A and the second motor control circuit 30B, so that each pointer moves the needle in units of 1 step at a specified time interval.

[0085] Furthermore, when the stopwatch function is executed or the pointer position is corrected, causing the pointers to fast forward, the CPU 23 performs current-controlled hand movement. In the current-controlled movement that causes the pointers to fast forward, the CPU 23 sets a lower target current value Imin and an upper target current value Imax for the first reference voltage generation circuit 62 and the second reference voltage generation circuit 63, respectively. After controlling the paired coils 130 to provide drive current, when the current value detected by the current detection circuit 60 exceeds the upper target current value Imax, it switches to a turn-off state where no drive current is provided; when the current value detected by the current detection circuit 60 is lower than the lower target current value Imin, it switches to a turn-on state where drive current is supplied. Moreover, if preset polarity switching conditions, such as the duration of the turn-on or turn-off state, are met, the CPU 23 switches the polarity of the drive current to control the movement.

[0086] [Effects of the First Embodiment]

[0087] According to the first embodiment described above, the following effects can be obtained.

[0088] By outputting a polarity detection pulse after system reset, the polarity of rotor 133 can be detected without driving the stepper motor. Therefore, for example, during the assembly of electronic clock 1, after aligning the pointer with the reference position, assembling the battery, and starting the clock, polarity matching can be achieved without moving the pointer. Thus, compared to the conventional method of moving the pointer from the reference position to perform polarity matching, the processing time for aligning the pointer with the reference position can be shortened.

[0089] Furthermore, at the current detection timing Td, just before the polarity detection pulse output ends, it is determined whether the current value exceeds the predetermined polarity discrimination current value Ith. Therefore, the pulse width of the polarity detection pulse can be fixed in advance. Thus, polarity detection processing can be performed in the same amount of time regardless of whether the polarity is consistent or inconsistent. Moreover, the process of detecting and determining the current value during the polarity detection pulse output only needs to be performed once. Therefore, compared to performing current value detection and determination multiple times during the polarity detection pulse output, control becomes simpler and power consumption is reduced.

[0090] By making the specified value in the polarity discrimination process, namely the polarity discrimination current value Ith, less than the lower limit target current value Imin in the drive process, the pulse width of the polarity detection pulse can be further reduced compared to setting the polarity discrimination current value Ith to the same value as the lower limit target current value Imin, thus reducing power consumption.

[0091] [Second Implementation]

[0092] Next, the electronic clock of the second embodiment will be described. Furthermore, in the second embodiment, the structure of the electronic clock 1 is the same as in the first embodiment, but the polarity detection processing method differs from that in the first embodiment. Therefore, referring to... Figure 9 The flowchart illustrates the polarity detection method of the second embodiment.

[0093] After the system reset is performed, CPU 23 executes step S21 to start the system and initialize the internal data, such as polarity information, stored in RAM 25. Therefore, the information stored in RAM 25 becomes the first polarity as the initial value.

[0094] Next, CPU23 executes step S22, outputs a polarity detection pulse to driver 50, and begins to apply voltage to coil 130.

[0095] Next, CPU23 executes step S23 to detect the current flowing through coil 130. Specifically, a voltage equivalent to the polarity discrimination current value Ith is selected as the generation voltage of the first reference voltage generation circuit 62, and it is detected whether the current I flowing through coil 130 exceeds the polarity discrimination current value Ith.

[0096] After current detection in step S23, CPU23 executes step S24 to determine whether the detected current I exceeds the polarity discrimination current value Ith. If the determination in step S24 is "no", CPU23 periodically executes steps S23 and S24.

[0097] On the other hand, if the determination in step S24 is "yes", the CPU23 executes step S25, stops outputting polarity detection pulses, and stops applying voltage.

[0098] Next, CPU23 executes step S26 to determine whether the time from the start of voltage application to the current I flowing through coil 130 reaching the specified current value, i.e., the polarity determination current value Ith, is within the specified time.

[0099] Here, Figure 10 This is a graph showing the waveform of current I when the polarity of rotor 133 matches the polarity of the polarity detection pulse. Figure 11 This is a diagram showing the waveform of current I when the polarity of rotor 133 is inconsistent with the polarity of the drive pulse.

[0100] like Figure 10 As shown, when the polarities are the same, rotor 133 repels, thus generating an induced current more quickly. On the other hand, as... Figure 11 As shown, when the polarities are inconsistent, the rotor 133 performs an attraction action, thus generating an induced current more slowly. Therefore, the CPU 23 performs current detection periodically according to T1, T2, ... By confirming whether the number of current detections at the moment when the detected current I reaches the polarity discrimination current value Ith is less than a preset judgment value, it can determine whether the time from voltage application to reaching the specified current value is within a specified period.

[0101] In this embodiment, after the initial voltage is applied, the time for performing 8 current detections is set to a predetermined time. If the current I reaches the polarity discrimination current value Ith before the 8th current detection timing (T8), the CPU 23 determines "yes" in step S26; otherwise, it determines "no" if the number of current detections exceeds 9. Figure 10 In the case where, during the 7th current detection timing (T7), the current I becomes the polarity discrimination current value Ith or higher, therefore, it is determined to be "yes" in step S26. On the other hand, in Figure 11 In the case where the current I becomes the polarity discrimination current value Ith or higher during the 11th current detection timing (T11), the determination is "No" in step S26.

[0102] If the determination in step S26 is "yes", the CPU23 executes step S27 in the same way as step S17 in the first embodiment, and determines that the position of the rotor 133, i.e., the polarity, is consistent with the IC control polarity, i.e., the polarity information stored in RAM25, and ends the polarity detection process.

[0103] In addition, if the determination in step S26 is "no", the CPU23 executes step S28 in the same way as steps S18 and S19 in the first embodiment, and determines that the position of the rotor 133, i.e., the polarity, is inconsistent with the polarity information stored in the IC control RAM25, and executes step S29 to change the polarity information stored in RAM25.

[0104] By performing the polarity detection process described above, in the second embodiment, the polarity information for motor control stored in RAM 25, i.e., the IC control polarity, is also consistent with the current polarity state of the stepper motor rotor. Therefore, when a drive pulse is output from CPU 23 according to the polarity information stored in RAM 25, the stepper motor can be reliably driven. Furthermore, the operation of the pointer during normal movement and fast-forward movement is the same as in the first embodiment, so further explanation is omitted.

[0105] [Effects of the Second Embodiment]

[0106] In the second embodiment described above, the same effect as in the first embodiment can also be achieved.

[0107] Furthermore, the current value can be periodically detected during the output of the polarity detection pulse, and the current detection process ends when the detected current I exceeds the polarity discrimination current value Ith, which is a predetermined value. Therefore, especially when the polarities are consistent, polarity can be detected in a short time. In addition, the output of the polarity detection pulse is stopped when the current I exceeds the polarity discrimination current value Ith, so the output time of the polarity detection pulse can be shortened, especially when the polarities are consistent, thus reducing power consumption.

[0108] Alternatively, in the second embodiment, the elapsed time from the start of outputting the polarity detection pulse can be measured. If the elapsed time exceeds a certain period while the detected current value does not exceed the polarity discrimination current value Ith, the output of the polarity detection pulse is stopped, and it is determined that the polarity of the rotor 133 is inconsistent with the polarity information stored in the RAM 25. For example, in step S24, if the determination is "no" and the number of current detections since the start of outputting the polarity detection pulse reaches a predetermined number, such as the 20th time, it is determined that the polarity detection processing has timed out, and steps S28 and S29 are executed.

[0109] If such a timeout determination is added, even if the detected current I does not exceed the polarity discrimination current value Ith, the polarity detection pulse will stop being output after a certain period of time, thus preventing the increase in power consumption caused by continuing to output the polarity detection pulse.

[0110] [Third Implementation]

[0111] Next, the electronic clock of the third embodiment will be described.

[0112] The specifications of IC20 in the electronic clock of the third embodiment are different from those of the first embodiment. That is, IC20 in the third embodiment cannot directly change the polarity of the drive pulse managed by IC20, i.e., the polarity information stored in RAM25, but changes it by outputting drive pulses.

[0113] Reference Figure 12 The flowchart illustrates the polarity detection method of the third embodiment of an electronic clock using an IC20 of this specification.

[0114] like Figure 12 As shown, in the third embodiment, steps S11 to S18 are the same as in the first embodiment, so the description is omitted. Then, after processing in step S18, the CPU 23 executes step S30 and outputs one drive pulse. This drive pulse is a fixed pulse with a preset pulse width, which is a pulse that can drive the stepper motor one step when the polarity of the rotor 133 matches the polarity information of the RAM 25.

[0115] In step S30, the rotor position is inconsistent with the IC control polarity, so even if one drive pulse is output, the rotor 133 will not rotate, and the polarity information stored in RAM 25 is changed. Therefore, it is possible to change the polarity information in RAM 25 to match the polarity of the rotor 133.

[0116] exist Figure 12 After the polarity detection process is completed, the polarity of rotor 133 can be made consistent with the polarity information stored in RAM 25. Therefore, during subsequent motor driving, drive pulses with consistent polarity can be output, which can reliably drive the stepper motor.

[0117] Alternatively, in the third embodiment, the same polarity determination method as in the second embodiment may be used. Figure 13 The flowchart illustrates the polarity detection process at this point. For example... Figure 13 As shown, steps S21 to S28 are the same processes as in the second embodiment, so their description is omitted. Then, after processing in step S28, the CPU 23 executes step S30, outputting one drive pulse to change the polarity information of the RAM 25, thereby aligning it with the polarity of the rotor 133. Furthermore, in Figure 13 In the processing, a timeout judgment can also be added.

[0118] [Effects of the Third Embodiment]

[0119] According to the third embodiment, in an electronic clock that uses IC20, which cannot directly change polarity information, the polarity of rotor 133 is detected, and a drive pulse is output only when it is inconsistent with the polarity information of RAM25. Thus, the polarity information can be changed to make it consistent without rotating rotor 133.

[0120] [Fourth Implementation]

[0121] according to Figure 14 and Figure 15 The electronic clock 1B of the fourth embodiment and its polarity detection process are explained.

[0122] like Figure 14 As shown, the electronic clock 1B adds a hand position detection mechanism compared to the electronic clock 1 of the first embodiment. Specifically, the movement 10B of the electronic clock 1B has a light-emitting element 71 and a light-receiving element 72 as a hand position detection mechanism to detect that the hand is at a reference position. Specifically, it includes a light-emitting element 71 and a light-receiving element 72 arranged to hold the gear train that drives the second hand 3, and a light-emitting element 71 and a light-receiving element 72 arranged to hold the gear train that drives the minute hand 4 and the hour hand 5. Furthermore, the IC 20B of the electronic clock 1B has the same structure as the IC 20 of the first embodiment, except that it has terminals O5 to O8 connected to the light-emitting element 71 and the light-receiving element 72; therefore, its description is omitted.

[0123] In the gear train that drives the second hand 3, when the second hand 3 is at the 0-second position (a reference position), a detection hole is formed between the light-emitting element 71 and the light-receiving element 72. When the second hand 3 is at the reference position, the light-receiving element 72 receives the detection light output from the light-emitting element 71. Thus, the second hand 3 can be detected as being at the reference position. Similarly, when the minute hand 4 and the hour hand 5 are also at the reference position (0:00), the light-receiving element 72 receives the detection light from the light-emitting element 71, thereby enabling the detection of their positions at the reference position.

[0124] Furthermore, the electronic clock 1B has a power generation device such as a solar panel, and the battery 12 is composed of a secondary battery so that it can be charged with the power generated by the power generation device.

[0125] Next, refer to Figure 15 The flowchart illustrates the control processing in electronic clock 1B.

[0126] During normal operation such as when the pointer is moving, or when the stopwatch is in operation, the CPU23 of IC20B executes step S41 to periodically detect the battery voltage.

[0127] Next, CPU23 executes step S42 to determine whether the voltage detected in step S41 has dropped below the preset energy-saving migration voltage. If the determination in step S42 is "no", CPU23 repeatedly executes steps S41 and S42.

[0128] If the determination in step S42 is "yes", CPU 23 executes step S43, moves the pointer to the reference position, and switches to power-saving mode. In power-saving mode, CPU 23 continues to execute the timekeeping, but does not drive the first motor 13 and the second motor 14, and the pointer remains stationary. Therefore, the second hand 3, minute hand 4, and hour hand 5 are stopped at the reference position.

[0129] After switching to the power-saving mode in step S43, CPU23 executes step S44 to periodically check the battery voltage.

[0130] Next, CPU23 executes step S45 to determine whether the voltage detected in step S44 has returned to or above the preset energy-saving release voltage. The energy-saving release voltage is a voltage higher than the energy-saving transition voltage. When the battery voltage rises due to the battery 12 being charged by the power generation device, CPU23 determines "yes" in step S45.

[0131] When the determination in step S45 is "yes", CPU23 executes step S46 to deactivate the power-saving mode. When the power-saving mode is deactivated, CPU23 moves the second hand 3, minute hand 4, and hour hand 5 to the position indicating the time in fast forward mode, restores normal operation, returns to step S41, and continues control.

[0132] On the other hand, if the determination in step S45 is "no", the CPU23 executes step S47 to determine whether the voltage detected in step S44 has dropped below the IC operating voltage. The IC operating voltage is a voltage lower than the power-saving migration voltage.

[0133] If the result is "no" in step S47, CPU23 returns to step S44 to continue control.

[0134] On the other hand, if the determination in step S47 is "yes", CPU 23 executes step S48 and stops the operation of IC 20B. As a result, internal data such as polarity information stored in RAM 25 is lost.

[0135] Then, in step S49, during the period when the battery voltage is lower than the preset system startup voltage (i.e., when the determination in step S49 is "No"), the IC operation remains in a stopped state. The system startup voltage is a voltage value higher than the IC operating voltage, and is preferably set to a voltage value higher than the energy-saving transition voltage so that the system does not switch to energy-saving mode after startup.

[0136] When the power generation device charges the battery 12 and the battery voltage reaches or exceeds the system startup voltage, and the determination in step S49 is "yes", the CPU 23 executes the polarity detection processing in step S50. The polarity detection processing is the same as any of the polarity detection processing in embodiments 1 to 3, therefore, its description is omitted. That is, when the polarity information of RAM 25 can be directly changed according to the specifications of IC 20, the same polarity detection processing is performed. Figure 6 or Figure 9 The same polarity detection processing is performed. Additionally, in cases where a drive pulse is required to change the polarity information of RAM25 according to IC20 specifications, the same polarity detection process is executed. Figure 12 or Figure 13 The same polarity detection process.

[0137] After performing the polarity detection process in step S50, CPU23 executes step S51 to perform reference position detection processing based on the light-emitting element 71 and the light-receiving element 72. During this time, the rotor 133 does not rotate in the polarity detection process of step S50; therefore, the pointer position remains at the reference position after the movement in step S43. Thus, in step S51, the first reference position detection operation can detect whether each pointer is at the reference position.

[0138] After detecting the reference position in step S51, CPU 23 executes step S52 to begin normal operation. After normal operation begins, the hands of the clock also start moving; however, since the operation of IC 20 stops and internal data is lost, there is a high probability that the indicated time is different from the current time. In this case, the user performs time setting. For example, if the electronic clock 1B has the function of receiving standard radio waves or satellite signals for time setting, a forced reception operation can be performed. Alternatively, if the electronic clock 1B is set manually using the crown 6, button A 7, and button B 8, time setting can be achieved simply by manually moving the hands.

[0139] [Effects of the fourth implementation method]

[0140] According to the electronic clock 1B of this embodiment, when the IC20B stops operating and the polarity information is lost before the system starts up, the polarity detection process in step S50 is performed. Therefore, the polarity of the rotor 133 can be detected without causing the rotor 133 to operate. Thus, when switching to energy-saving mode, the polarity detection process can be performed without moving the pointer that has moved to the reference position. Afterward, the reference position detection process in step S51 can be performed when the pointer is at the reference position. Therefore, the reference position detection process can be completed in a short time, and the hand movement for reference position alignment is not required, thereby reducing power consumption.

[0141] Furthermore, when the remaining capacity of the battery 12, which serves as a secondary battery, is lower than the energy-saving mode migration voltage, which is a predetermined threshold, the pointer is moved to the reference position and the drive is stopped. Therefore, the voltage drop of the battery 12 can be suppressed.

[0142] [Other Implementation Methods]

[0143] Furthermore, the present invention is not limited to the embodiments described above, and various modifications can be implemented within the scope of the spirit of the present invention.

[0144] For example, the polarity discrimination current value Ith in each of the above embodiments is the same, but the polarity discrimination current value Ith in the first and third embodiments may be different from the polarity discrimination current value Ith in the second and fourth embodiments.

[0145] The storage unit for storing polarity information is not limited to RAM 25, but may also be an internal storage unit located within CPU 23.

[0146] In the fourth embodiment described above, when switching to the energy-saving mode, the second hand 3, the minute hand 4, and the hour hand 5 are moved to the reference position respectively. Alternatively, the minute hand 4 and the hour hand 5 can be moved to the reference position, and the second hand 3 can be moved to the mode position indicating the switch to the energy-saving mode, such as the 45-second position, and then stop.

[0147] Furthermore, in the case of the electronic clock 1B equipped with a date wheel, the date wheel can be moved to the reference position and then stopped. Most watches lack a hand position detection mechanism for the date wheel, requiring manual operation to move it to the reference position for alignment. Therefore, if the date wheel is pre-moved to the reference position in power-saving mode, it does not need to be moved when aligned, allowing for quick alignment and reducing power consumption.

[0148] Furthermore, the polarity detection process is not limited to being implemented when RAM25 is initialized; it can also be implemented periodically during the hand movement. For example, in an electronic clock with a built-in accelerometer sensor, it can be implemented when the possibility of a change in polarity due to the rotor 133 rotating is detected when the electronic clock falls.

[0149] [Summary of this invention]

[0150] The electronic clock of the present invention comprises: a hand; a stepper motor having a coil and driving the hand; a drive circuit driving the stepper motor; a control unit controlling the drive circuit; a current detection circuit detecting the current value flowing through the drive circuit; and a storage unit storing polarity information of drive pulses output from the control unit to the drive circuit. When the storage unit is initialized, the control unit initializes the polarity information stored in the storage unit, outputs a polarity detection pulse indicating that the stepper motor has not rotated one step to the drive circuit according to the initialized polarity information, and performs polarity discrimination processing to determine whether the polarity of the stepper motor is consistent with the polarity information based on the current value detected by the current detection circuit in accordance with the output of the polarity detection pulse. If they are inconsistent, the polarity information is changed.

[0151] According to the electronic clock of the present invention, a polarity detection pulse (i.e., a pulse width smaller than the drive pulse) is output based on the initialized polarity information, indicating that the stepper motor has not rotated one step. Therefore, it is possible to determine whether the polarity of the stepper motor matches the initialized polarity information without driving the stepper motor, and change the polarity information if they do not match. That is, the polarity can be matched while maintaining the pointer position during initialization. Therefore, when aligning the reference position, it is not necessary to output drive pulses in the forward and reverse directions to move the pointer as in the past, thus shortening the processing time for aligning the pointer with the reference position.

[0152] In the electronic clock of the present invention, it is preferable that the control unit determines whether the current value exceeds a predetermined value based on the output of the polarity detection pulse, and if the current value exceeds the predetermined value, it determines that the polarity of the stepper motor is consistent with the polarity information.

[0153] According to the electronic clock of the present invention, it is possible to determine whether the current value exceeds a predetermined value just before the polarity detection pulse output ends, thus the pulse width of the polarity detection pulse can be fixed in advance. Therefore, polarity detection processing can be performed in the same amount of time regardless of whether the polarity is consistent or inconsistent. Furthermore, since the current value detection and determination process is performed only once during the output of the polarity detection pulse, power consumption can be reduced compared to the case where the current value detection and determination process is performed multiple times during the output of the polarity detection pulse.

[0154] In the electronic clock of the present invention, preferably, the current detection circuit detects the current value during the output of the polarity detection pulse, and the control unit measures the elapsed time from the start of the output of the polarity detection pulse. If the elapsed time until the moment when the current value is detected to exceed a predetermined value is within a predetermined time, it is determined that the polarity of the stepper motor is consistent with the polarity information.

[0155] According to the electronic clock of the present invention, the current value is detected in the output of the polarity detection pulse, and the polarity is determined by the elapsed time until the current value is detected to exceed a predetermined value. Therefore, especially when the polarities are consistent, the processing can be completed in a short time.

[0156] In the electronic clock of the present invention, preferably, the control unit stops outputting the polarity detection pulse when it detects that the current value exceeds a predetermined value.

[0157] The electronic clock according to the present invention can stop outputting polarity detection pulses when the current value exceeds a predetermined value. Therefore, especially when the polarities are consistent, the output time of the polarity detection pulses can be shortened, and power consumption can be reduced.

[0158] In the electronic clock of the present invention, preferably, the control unit measures the elapsed time from the start of outputting the polarity detection pulse, and when the elapsed time exceeds a certain time while the current value does not exceed a predetermined value, the output of the polarity detection pulse is stopped, and it is determined that the polarity is inconsistent with the polarity information.

[0159] According to the present invention, the electronic clock stops outputting polarity detection pulses after a certain period of time, even if the detected current value does not exceed the specified value. Therefore, it is possible to prevent the increase in power consumption caused by the continued output of polarity detection pulses.

[0160] In the electronic clock of the present invention, preferably, the driving circuit is controlled to be in a conducting state that supplies driving current to the coil and in a turning-off state that does not supply driving current. In the driving process of the pointer, the control unit compares the current value detected by the current detection circuit with the target current value, and controls the driving circuit to be in the conducting state or the turning-off state according to the comparison result. The predetermined value in the polarity discrimination process is less than the target current value in the driving process.

[0161] According to the electronic clock of the present invention, the predetermined value in the polarity determination process is less than the target current value in the drive process. Therefore, compared with the case where the predetermined value is set to the same value as the target current value, the pulse width of the polarity detection pulse can be further reduced, and power consumption can be reduced.

[0162] In the electronic clock of the present invention, preferably, when the control unit determines that the polarity of the stepper motor is inconsistent with the polarity information, it outputs a drive pulse to the drive circuit according to the initialized polarity information, which drives the stepper motor one step when the polarity of the stepper motor is consistent with the polarity information, thereby changing the polarity information.

[0163] According to the present invention, when it is determined that the polarity of the stepper motor is inconsistent with the polarity information, a drive pulse with inconsistent polarity is output. Therefore, it is possible to change the polarity information stored in the storage unit without driving the stepper motor. Thus, it can also be applied to electronic clocks where the polarity information cannot be directly changed according to the IC specifications.

[0164] In the electronic clock of the present invention, preferably, the electronic clock has: a secondary battery; and a power generation device capable of charging the secondary battery, wherein the control unit, when the remaining amount of the secondary battery is lower than a predetermined threshold, moves at least one pointer to a reference position and stops driving the moved pointer.

[0165] According to the electronic clock of the present invention, when the remaining capacity of the secondary battery (i.e., the battery voltage) charged by a power generation device such as a solar panel is lower than a predetermined threshold, the pointer is moved to a reference position and the operation stops, thus suppressing the voltage drop of the secondary battery. Furthermore, assuming that after the storage unit is initialized due to a further drop in battery voltage, and the system is started by charging the secondary battery through the power generation device to raise its voltage, if the pointer is at the reference position, the pointer can be aligned to the reference position without moving it.

[0166] In the electronic clock of the present invention, preferably, the electronic clock has a pointer position detection mechanism for detecting that at least one pointer is located at the reference position, and the control unit performs pointer position detection processing using the pointer position detection mechanism after the polarity discrimination processing when the storage unit is initialized.

[0167] According to the present invention, when polarity determination processing is performed while the pointer is at the reference position, the pointer does not move from the reference position. Therefore, when performing pointer position detection processing using a pointer position detection mechanism, the pointer can be detected in the shortest time, thus reducing the pointer position detection processing time to a minimum and correspondingly reducing power consumption.

[0168] The electronic clock of the present invention is characterized by comprising: a pointer; a stepper motor having a coil and driving the pointer; a drive circuit driving the stepper motor; a control unit controlling the drive circuit; a current detection circuit detecting the current value flowing through the drive circuit; and a storage unit storing polarity information of drive pulses output from the control unit to the drive circuit. The control unit outputs a polarity detection pulse to the drive circuit based on the polarity information stored in the storage unit, indicating that the stepper motor has not rotated one step. The current detection circuit detects the current value in the output of the polarity detection pulse. The control unit measures the elapsed time from the start of outputting the polarity detection pulse. If the elapsed time until the current value is detected to exceed a predetermined value is within a predetermined time, it determines that the polarity of the stepper motor is consistent with the polarity information. If the elapsed time exceeds the predetermined time, it determines that the polarity of the stepper motor is inconsistent with the polarity information. If inconsistent, the polarity information is changed.

[0169] According to the electronic clock of the present invention, based on the polarity information stored in the storage unit, a polarity detection pulse (i.e., a pulse width smaller than the drive pulse) is output for each step the stepper motor does not rotate by one step. Therefore, without driving the stepper motor, it is possible to determine whether the polarity of the stepper motor matches the stored polarity information, and if they do not match, the polarity information is changed. That is, polarity can be matched while maintaining the pointer position. Therefore, when performing reference position alignment, it is not necessary to output drive pulses in the forward and reverse directions to move the pointer as in the past, thus shortening the processing time for reference position alignment.

[0170] Furthermore, the current value is detected in the output of the polarity detection pulse, and the polarity is determined by the elapsed time until the current value exceeds the specified value. Therefore, especially when the polarities are consistent, the processing can be completed in a short time.

[0171] The control method for an electronic clock of the present invention is characterized in that the electronic clock has: a pointer; a stepper motor having a coil and driving the pointer; a drive circuit driving the stepper motor; a current detection circuit detecting the current value flowing through the drive circuit; and a storage unit storing polarity information of drive pulses output to the drive circuit. When the storage unit is initialized, the polarity information stored in the storage unit is initialized. Based on the initialized polarity information, a polarity detection pulse indicating that the stepper motor has not rotated one step is output to the drive circuit. Based on the current value detected by the current detection circuit corresponding to the output of the polarity detection pulse, polarity discrimination processing is performed to determine whether the polarity of the stepper motor is consistent with the polarity information. If they are inconsistent, the polarity information is changed.

[0172] According to the control method of the electronic clock of the present invention, based on the initialized polarity information, a polarity detection pulse (i.e., a pulse width smaller than the drive pulse) is output when the stepper motor has not rotated one step. Therefore, without driving the stepper motor, it is possible to determine whether the polarity of the stepper motor is consistent with the initialized polarity information, and if inconsistent, the polarity information is changed. That is, the polarity can be matched while maintaining the pointer position during initialization. Therefore, when performing reference position alignment, it is not necessary to output drive pulses in the forward and reverse directions to move the pointer as in the past, thus shortening the processing time for reference position alignment.

[0173] The control method for an electronic clock of the present invention is characterized in that the electronic clock has: a pointer; a stepper motor having a coil and driving the pointer; a drive circuit driving the stepper motor; a current detection circuit detecting the current value flowing through the drive circuit; and a storage unit storing polarity information of drive pulses output to the drive circuit. Based on the polarity information stored in the storage unit, the drive circuit outputs a polarity detection pulse indicating that the stepper motor has not rotated one step. The current detection circuit detects the current value during the output of the polarity detection pulse, measures the elapsed time from the start of outputting the polarity detection pulse, and determines that the polarity of the stepper motor is consistent with the polarity information if the elapsed time until the current value is detected to exceed a predetermined value is within a predetermined time. If the elapsed time exceeds the predetermined time, the polarity of the stepper motor is determined to be inconsistent with the polarity information, and the polarity information is changed if there is inconsistency.

[0174] According to the control method of the electronic clock of the present invention, a polarity detection pulse (i.e., a pulse width smaller than the drive pulse) is output based on the polarity information stored in the storage unit, indicating that the stepper motor has not rotated one step. Therefore, without driving the stepper motor, it is possible to determine whether the polarity of the stepper motor matches the stored polarity information, and if they do not match, the polarity information is changed. That is, polarity matching can be achieved while maintaining the pointer position. Therefore, when performing reference position alignment, it is not necessary to output drive pulses in the forward and reverse directions to move the pointer as in the past, thus shortening the processing time for reference position alignment. Furthermore, the current value is detected in the output of the polarity detection pulse, and the polarity is determined by the elapsed time until the current value exceeds a predetermined value. Therefore, especially when the polarity matches, the processing can be completed in a short time.

Claims

1. An electronic timepiece characterized by comprising: It has the following characteristics: pointer; A stepper motor having a coil and driving the pointer; A drive circuit that drives the stepper motor; The control unit outputs drive pulses to the drive circuit to control the drive circuit; A current detection circuit that detects the current value flowing through the drive circuit; as well as Random access memory that stores the polarity information from the driving pulse. When the random access memory is initialized by a system reset, the control unit initializes the polarity information stored in the random access memory. After the polarity information stored in the random access memory is initialized, the first polarity is stored in the random access memory. Based on the first polarity stored in the random access memory, the drive circuit outputs a polarity detection pulse indicating that the stepper motor has not rotated one step. Based on the current value detected by the current detection circuit and the output of the polarity detection pulse, a polarity discrimination process is performed to determine whether the polarity of the stepper motor is consistent with the first polarity. If they are inconsistent, the first polarity is changed.

2. The electronic clock according to claim 1, characterized in that, The control unit also determines whether the current value exceeds a specified value based on the output of the polarity detection pulse. If the current value exceeds the specified value, it is determined that the polarity of the stepper motor is consistent with the first polarity.

3. The electronic clock according to claim 1, characterized in that, The current detection circuit also detects the current value in the output of the polarity detection pulse. The control unit also measures the elapsed time from the start of outputting the polarity detection pulse, and if the elapsed time until the current value is detected to exceed the specified value is within the specified time, it determines that the polarity of the stepper motor is consistent with the first polarity.

4. The electronic clock according to claim 3, characterized in that, The control unit also stops outputting the polarity detection pulse when it detects that the current value exceeds a predetermined value.

5. The electronic clock according to claim 3, characterized in that, The control unit also measures the elapsed time from the start of outputting the polarity detection pulse. If the elapsed time exceeds the predetermined time while the current value does not exceed the predetermined value, the output of the polarity detection pulse is stopped, and it is determined that the polarity of the stepper motor is inconsistent with the first polarity.

6. The electronic clock according to claim 1, characterized in that, The driving circuit is also controlled to be in an on state that supplies driving current to the coil and in an off state that does not supply driving current. The control unit also compares the current value detected by the current detection circuit with the target current value during the pointer's driving process, and controls the driving circuit to either the on state or the off state based on the comparison result. The current value detected by the current detection circuit in the polarity discrimination process is less than the target current value in the driving process.

7. The electronic clock according to claim 1, characterized in that, When the control unit determines that the polarity of the stepper motor is inconsistent with the first polarity, it outputs the drive pulse, causing the drive circuit to drive the stepper motor one step and change the first polarity of the drive pulse.

8. The electronic clock according to claim 1, characterized in that, The electronic clock has the following features: Secondary batteries; and A power generation device capable of charging the secondary battery. The control unit also moves the pointer to a reference position and stops the pointer from moving when the remaining amount of the secondary battery is lower than a specified threshold.

9. An electronic clock, characterized in that, It has the following characteristics: pointer; A stepper motor having a coil and driving the pointer; A drive circuit that drives the stepper motor; The control unit outputs drive pulses to the drive circuit to control the drive circuit; A current detection circuit that detects the current value flowing through the drive circuit; as well as Random access memory that stores the polarity information of the driving pulse. The control unit outputs a polarity detection pulse to the drive circuit based on the polarity information stored in the random access memory, indicating that the stepper motor has not rotated one step. The current detection circuit detects the current value in the output of the polarity detection pulse. The control unit measures the elapsed time from the start of outputting the polarity detection pulse. If the elapsed time until the current value is detected to exceed the specified value is within the specified time, it determines that the polarity of the stepper motor is consistent with the polarity information. If the elapsed time until the current value is detected to exceed the specified value exceeds the specified time, it determines that the polarity of the stepper motor is inconsistent with the polarity information. If inconsistent, the polarity information is changed.

10. A method for controlling an electronic clock, the electronic clock comprising: a pointer; a stepper motor having a coil and driving the pointer; The system includes a drive circuit for driving the stepper motor; a current detection circuit for detecting the current flowing through the drive circuit; and a random access memory for storing the polarity information of the drive pulses output to the drive circuit. Its characteristic is that the control unit performs: When the random access memory is initialized by a system reset, the polarity information stored in the random access memory is initialized. After the polarity information stored in the random access memory is initialized, the first polarity is stored in the random access memory. According to the first polarity stored in the random access memory, the drive circuit outputs a polarity detection pulse indicating that the stepper motor has not rotated one step; Based on the current value detected by the current detection circuit and the polarity detection pulse, a polarity discrimination process is performed to determine whether the polarity of the stepper motor is consistent with the first polarity. Change the first polarity in case of inconsistency.

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