JP2011188734A - Stepping motor control circuit, and analog electronic clock - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect reduction in a power supply voltage without arranging a dedicated circuit for detecting a voltage such as a comparator circuit. <P>SOLUTION: A controller controls the driving of a stepping motor 109 by selecting any of a plurality of main driving pulses P1 having different driving energy from one another or a compensation driving pulses P2 having energy larger than that of the main driving pulses P1, according to rotation status detected by a rotation detector. The controller also determines that the voltage of a battery 112 is reduced to a value lower than a predetermined value, if the rotation detector detects a driving energy shortage when the stepping motor 109 is driven with a predetermined driving pulse such as a main driving pulse P1max having maximum driving energy. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a stepping motor control circuit and an analog electronic timepiece using the stepping motor control circuit.

Conventionally, stepping motors have been used for applications such as driving time hands of analog electronic timepieces.
For example, in an analog electronic wristwatch, a battery is used as a power source for driving the stepping motor and the like, and a power supply voltage detection means is provided for urging the battery to be replaced when the battery voltage falls below a predetermined value. Yes.
The conventional power supply voltage detection means includes a comparator circuit for comparing the power supply voltage with a predetermined reference voltage. The comparator circuit detects that the power supply voltage has fallen below the reference voltage, so that the battery can be replaced or charged. A function for promoting the operation is realized (for example, see Patent Documents 1 and 2).
In addition, in devices equipped with a secondary battery as a power source, in order to prevent battery deterioration, when overcharge is detected using a comparator circuit, both ends of the secondary battery are short-circuited and discharged to a voltage above a certain value. I try not to be.

  However, the comparator circuit requires a large area in terms of circuit elements such as the use of a high resistance, which increases the size of the integrated circuit (IC), which is a problem in analog electronic watches and the like that are required to be small and light. .

JP 2002-372588 A Japanese Patent Laid-Open No. 2003-307577

The present invention has been made in view of the above problems, and an object of the present invention is to be able to detect that a power supply voltage is out of a predetermined range without providing a voltage detection dedicated circuit such as a comparator circuit.
Another object of the present invention is to make it possible to detect a decrease in power supply voltage without providing a voltage detection dedicated circuit such as a comparator circuit.
Another object of the present invention is to prevent overcharging of a secondary battery as a power source without providing a voltage detection dedicated circuit such as a comparator circuit.

  According to the first aspect of the present invention, a power source that supplies power to at least the stepping motor, a rotation detection unit that detects a rotation state of the stepping motor, and a rotation state detected by the rotation detection unit, Control means for driving and controlling the stepping motor by selecting any one of a plurality of main drive pulses having different drive energies or a correction drive pulse having a drive energy larger than each of the main drive pulses. A stepping motor control circuit is provided, wherein the voltage of the power source is determined based on the rotation state of the stepping motor detected by the rotation detecting means when the stepping motor is driven by a predetermined driving pulse.

Here, the control means is configured to determine that the voltage of the power source has dropped below a predetermined value when the rotation detection means detects a lack of drive energy when the stepping motor is driven by a predetermined drive pulse. can do.
The power source includes a secondary battery and charging means for charging the secondary battery, and the control means is configured such that when the stepping motor is driven by a predetermined drive pulse, the rotation detecting means is the second battery. When overcharge of the secondary battery is detected, the secondary battery can be configured to stop charging.

  According to the second aspect of the present invention, the stepping motor control circuit is used in an analog electronic timepiece having a stepping motor for rotating the time hand and a stepping motor control circuit for controlling the stepping motor. An analog electronic timepiece is provided.

According to the stepping motor control circuit of the present invention, it is possible to detect that the power supply voltage is out of the predetermined range without providing a voltage detection dedicated circuit such as a comparator circuit. Further, it is possible to detect a drop in the power supply voltage without providing a voltage detection dedicated circuit such as a comparator circuit. Further, overcharging of the secondary battery as a power source can be prevented without providing a voltage detection dedicated circuit such as a comparator circuit.
Further, according to the analog electronic timepiece according to the invention, it is possible to detect that the power supply voltage is out of the predetermined range without providing a circuit dedicated to voltage detection such as a comparator circuit, and to promote battery replacement. It becomes possible. Further, according to the analog electronic timepiece of the invention, it is possible to detect that the power supply voltage is out of the predetermined range without providing a circuit dedicated to voltage detection such as a comparator circuit, and a secondary battery as a power supply. Can be prevented from overcharging.

1 is a block diagram of an analog electronic timepiece according to an embodiment of the present invention. It is a block diagram of the stepping motor used for the analog electronic timepiece which concerns on each embodiment of this invention. FIG. 6 is a timing diagram for explaining the operation of the stepping motor control circuit and the analog electronic timepiece according to the embodiment of the invention. It is a flowchart concerning a stepping motor control circuit and an analog electronic timepiece according to an embodiment of the present invention. It is a block diagram of an analog electronic timepiece according to another embodiment of the present invention. It is a timing diagram for demonstrating operation | movement of the stepping motor control circuit and analog electronic timepiece which concern on other embodiment of this invention. It is a flowchart concerning a stepping motor control circuit and an analog electronic timepiece according to another embodiment of the present invention. It is a flowchart concerning a stepping motor control circuit and an analog electronic timepiece according to another embodiment of the present invention.

FIG. 1 is a block diagram of an analog electronic timepiece using a stepping motor control circuit according to an embodiment of the present invention, and shows an example of an analog electronic wristwatch.
In FIG. 1, an analog electronic timepiece includes an oscillation circuit 101 that generates a signal of a predetermined frequency, a frequency dividing circuit 102 that divides the signal generated by the oscillation circuit 101 and generates a clock signal that serves as a time reference, and an electronic timepiece. A control circuit 103 that performs control of each electronic circuit element that constitutes, control of change of drive pulse, etc., and pulse down for pulse-down of the main drive pulse P1 every time a clock signal from the frequency divider circuit 102 is timed. A pulse down counter circuit 105 that outputs a control signal and resets a count value in response to a reset signal from the control circuit 103 and starts a clocking operation again is provided.

  The analog electronic timepiece is selected from the main drive pulse generation circuit 104 and the control circuit 103 that select and output one of a plurality of types of main drive pulses P1 having different drive energies based on a control signal from the control circuit 103. Based on the control signal, the correction drive pulse generation circuit 108 that outputs the correction drive pulse P2 whose energy is larger than that of the main drive pulse P1, the main drive pulse P1 from the main drive pulse generation circuit 104, and the correction drive pulse generation circuit 108. Motor driving circuit 106 for rotationally driving the stepping motor 109 in response to the correction driving pulse P2 from the motor, the stepping motor 109, the analog display unit 110 that is rotationally driven by the stepping motor 109 and has a time hand for displaying the time, etc., stepping Generated by free vibration after driving the motor 109 The rotation detection circuit 107 detects an induced signal VRs exceeding a predetermined reference threshold voltage Vcomp in a predetermined rotation detection period, and the rotation detection circuit 107 detects the induced signal VRs exceeding the reference threshold voltage Vcomp in any section within the rotation detection period. A detection section determination circuit 111 that determines whether the detection has been performed is provided.

The battery 112 is a power source for the analog electronic timepiece and functions as at least a power source for the stepping motor 109.
The control circuit 103 resets the pulse down counter circuit 105 under a certain condition and restarts the count operation from the initial value, and whether the induced signal VRs exceeds the reference threshold voltage Vcomp in each interval. And a function for determining the rotation state of the stepping motor 108 (whether it has rotated, whether the drive energy is sufficient, etc.) or the like. In addition, the control circuit 103 includes a voltage determination unit 103a that determines the voltage of the battery 112 based on the pattern in the section in which the induced signal VRs exceeding the reference threshold voltage Vcomp is detected.

As will be described later, the rotation detection period for detecting the rotation state of the stepping motor 109 is provided immediately after the driving of the stepping motor 109 is stopped, and is divided into a plurality of sections (three sections T1 to T3 in this embodiment). Has been.
The rotation detection circuit 107 is a known rotation detection circuit. When the rotor of the stepping motor 109 moves at a certain speed or more, such as when the stepping motor 109 rotates, an induced signal VRs exceeding the reference threshold voltage Vcomp. When the stepping motor 109 does not rotate and the rotor of the stepping motor 109 does not move above a certain speed, the induced signal VRs exceeding the reference threshold voltage Vcomp is not detected. ing.

  Here, the oscillation circuit 101 and the frequency dividing circuit 102 constitute a signal generation unit, and the analog display unit 110 constitutes a time display unit. The rotation detection circuit 107 and the detection section determination circuit 111 constitute rotation detection means. The main drive pulse generation circuit 104 and the correction drive pulse generation circuit 108 constitute drive pulse generation means. The motor drive circuit 106 constitutes motor drive means. The voltage determination unit 103a constitutes a voltage determination unit. The oscillation circuit 101, the frequency divider circuit 102, the pulse down counter circuit 105, the control circuit 103, the voltage determination unit 103a, the main drive pulse generation circuit 104, the correction drive pulse generation circuit 108, and the motor drive circuit 106 constitute control means. .

FIG. 2 is a configuration diagram of the stepping motor 109 used in the embodiment of the present invention, and shows an example of a timepiece stepping motor generally used in an analog electronic timepiece.
In FIG. 2, a stepping motor 109 is wound around a stator 201 having a rotor accommodating through hole 203, a rotor 202 rotatably disposed in the rotor accommodating through hole 203, a magnetic core 208 joined to the stator 201, and a magnetic core 208. A rotated coil 209 is provided. When the stepping motor 108 is used in an analog electronic timepiece, the stator 201 and the magnetic core 208 are fixed to a base plate (not shown) by screws or caulking (not shown) and joined to each other. The coil 209 has a first terminal OUT1 and a second terminal OUT2.

  The rotor 202 is magnetized to two poles (S pole and N pole). A plurality of (two in this embodiment) notch portions (outer notches) 206 and 207 are provided at positions facing each other across the rotor accommodating through hole 203 at the outer end portion of the stator 201 formed of a magnetic material. Is provided. Saturable portions 210 and 211 are provided between the outer notches 206 and 207 and the rotor accommodating through hole 203.

  The saturable portions 210 and 211 are configured not to be magnetically saturated by the magnetic flux of the rotor 202 but to be magnetically saturated when the coil 209 is excited to increase the magnetic resistance. The through hole 203 for accommodating the rotor has a circular hole shape in which a plurality of (two in the present embodiment) half-moon-shaped notches (inner notches) 204 and 205 are integrally formed at the opposing portion of the through hole having a circular outline. It is configured.

  The notches 204 and 205 constitute a positioning part for determining the stop position of the rotor 202. In a state where the coil 209 is not excited, the rotor 202 has a position corresponding to the positioning portion as shown in FIG. 2, in other words, a line segment connecting the notches 204 and 205 with the magnetic pole axis A of the rotor 202. Is stably stopped at a position orthogonal to the angle (angle θ0 position).

  Now, a rectangular-wave drive pulse of one polarity is supplied from the motor drive circuit 106 between the terminals OUT1 and OUT2 of the coil 209 (for example, the first terminal OUT1 side is positive and the second terminal OUT2 side is negative). When a current i flows in the direction of the arrow 2, a magnetic flux is generated in the stator 201 in the direction of the broken line arrow. As a result, the saturable portions 210 and 211 are saturated and the magnetic resistance is increased, and then the rotor 202 rotates 180 degrees in the direction of the arrow in FIG. 2 due to the interaction between the magnetic pole generated in the stator 201 and the magnetic pole of the rotor 202. Then, the magnetic pole axis A stops stably at the angle θ1 position. Incidentally, the rotation direction (counterclockwise direction in FIG. 2) for causing the normal operation (in this embodiment, since it is an analog electronic timepiece to move the hand) by rotating the stepping motor 109 is a positive direction. The reverse (clockwise direction) is the reverse direction.

  Next, a drive pulse having a reverse polarity is supplied from the motor drive circuit 107 to the terminals OUT1 and OUT2 of the coil 209 (the first terminal OUT1 side is a negative electrode and the second terminal OUT2 is so as to have a reverse polarity to the drive). When a current is passed in the opposite arrow direction in FIG. 2, a magnetic flux is generated in the stator 201 in the opposite arrow direction. As a result, the saturable portions 210 and 211 are first saturated, and then the rotor 202 rotates 180 degrees in the same direction as described above due to the interaction between the magnetic poles generated in the stator 201 and the magnetic poles of the rotor 202, and the magnetic pole axis A Stops stably at the angle θ0 position.

Thereafter, by supplying signals with different polarities (alternating signals) to the coil 209 in this way, the above operation is repeated, and the rotor 202 can be continuously rotated 180 degrees in the direction of the arrow. It is configured as follows.
In the present embodiment, a plurality of types of main drive pulses P1n and correction drive pulses P2 having different drive energies are used as drive pulses. The rank n of the main drive pulse P1n has a plurality of ranks from the minimum value 1 to the maximum value m, and the drive energy of the drive pulse increases as the value of n increases. The correction drive pulse P2 is a large energy pulse that can forcibly rotate an overload, and the drive energy is set to be larger than each main drive pulse P1.

  FIG. 3 is a timing chart of the stepping motor 108 according to the present embodiment. The voltage state of the battery 112 and the induced signal VRs detected by the detection section determination circuit 111 are the reference threshold voltage Vcomp in the first section T1 to the third section. Whether to maintain or change the pattern (first section T1, second section T2, third section T3), stepping motor state, rotor 202 rotation trajectory, induction signal VRs generation timing, and drive pulse. The pulse control operation of “no” is also shown.

The detection period T is divided into a first section T1, a second section T2, and a third section T3. A predetermined time immediately after driving by the main drive pulse P1 is a first interval T1, a predetermined time after the first interval T1 is a second interval T2, and a predetermined time after the second interval is a third interval T3. In this way, the entire detection section T starting immediately after driving with the main drive pulse P1 is divided into a plurality of sections (three sections T1 to T3 in the present embodiment). In the present embodiment, there is no mask section that is a period during which no induced signal VRs is detected.
When the XY coordinate space where the main magnetic pole of the rotor 202 is located by rotation of the rotor 202 is divided into the first quadrant I to the fourth quadrant IV, the first section T1 to the third section T3 are as follows. Can be represented.

  That is, when the battery 112 is in a normal load state and the voltage of the battery 112 is a predetermined voltage (a voltage at which the stepping motor 109 exhibits “reasonable rotation”), the first section T1 is the second space in the space centered on the rotor 202. In the quadrant II and the third quadrant III, the section for determining the first forward rotation state of the rotor 202 and the section for determining the first reverse rotation state, the second section T2 is the first reverse direction of the rotor 202 in the third quadrant III. The third section T3 is a section for determining the second forward rotation situation and the second reverse rotation situation of the rotor 202 in the third quadrant III in the section for judging the rotation situation and the second forward rotation situation. Here, the normal load means a load that is driven at a normal time, and in the present embodiment, a load when driving the time hand (hour hand, minute hand, second hand) of the analog display unit 110 is a normal load. .

  P1 represents the main drive pulse and also represents the period driven by the main drive pulse P1. In an XY coordinate section centered on the rotation center of the rotor 202, a is a region where the rotor 202 is first rotated in the positive direction in the second quadrant by driving with the main drive pulse P1, and b is first positive in the third quadrant. In the third quadrant, c is a region that rotates in the reverse direction first, and d is a region that rotates in the positive direction for the second time in the third quadrant. In the third quadrant, e is a region that rotates in the reverse direction for the second time.

  For example, in FIG. 3, in the stepping motor control circuit according to the present embodiment, the induced signal VRs generated in the region b is detected in the first section T1 when the voltage of the battery 112 indicates “a reasonable margin of rotation”. The induced signal VRs generated in the region c is detected in the first interval T1 and the second interval T2, and the induced signal VRs generated in the region d is detected in the second interval T2 and the third interval T3, and is generated in the region e. The induced signal VRs is detected in the third section T3.

In addition, when the battery 112 is a voltage lower than the voltage indicating the “reasonable margin rotation” by a predetermined value (the voltage indicating that the stepping motor 109 is “a little marginal rotation”), the induced signal VRs generated in the region a is the first. The induced signal VRs detected in the first section T1 and generated in the area b is detected in the first section T1 and the second section T2, and the induced signal VRs generated in the area c is detected in the second section T2 and the third section T3. The induced signal VRs generated in the region d is detected in the third section T3.
Similarly, as shown in FIG. 3, the pattern of the induced signal VRs corresponding to the voltage of the secondary battery 112 is detected. The control circuit 103 performs pulse control such as rank-up, rank maintenance, rank-down, etc. of the main drive pulse P1 according to the pattern of the induced signal VRs.

The determination value of the induced signal VRs in each section represents “1” when the induced signal VRs exceeds the reference threshold voltage Vcomp, and “0” when the induced signal VRs does not exceed the reference threshold voltage Vcomp. A section in which the determination value may be “1” or “0” is represented as “1/0”.
The pattern (1/0, 0, 0) indicates a state in which the voltage of the battery 112 is the lowest in the example of FIG. 3, and indicates a state in which the stepping motor 109 has not rotated in the current driving. Since the stepping motor 109 did not rotate, the control circuit 103 forcibly rotates the stepping motor 109 by driving with the correction driving pulse P2, and the main driving pulse P1 is the main driving energy having one rank driving energy at the next driving. Pulse control is performed so that the driving pulse P1 is changed (ranked up) and driven.

In the pattern (1/0, 0, 1), the voltage of the battery 112 is the second lowest after the pattern (1/0, 0, 0), and the stepping motor 109 rotates in this driving, but there is no margin in driving energy. It is a rotation. Since the control circuit 103 is rotating with no margin, it is not driven by the correction drive pulse P2, but performs pulse control so that the main drive pulse P1 is driven up one rank during the next drive.
In the pattern (1, 1, 1/0), the voltage of the battery 112 is the next lower than that of the pattern (1/0, 0, 1), and the stepping motor 109 is rotated in this driving, but there is a margin in driving energy. It shows that there is little rotation. Since the control circuit 103 is rotating with a little margin, the rank of the main drive pulse P1 is maintained without being ranked up.

The pattern (0, 1, 1/0) indicates that the voltage of the battery 112 is the highest, the stepping motor 109 is rotated by the current driving, and the driving energy is a rotation with an appropriate margin. Since the control circuit 103 rotates at an appropriate margin, the rank of the main drive pulse P1 is maintained without being ranked up.
FIG. 4 is a flowchart showing the operation of the embodiment of the present invention.

Hereinafter, the operation of the present embodiment will be described in detail with reference to FIGS.
In FIG. 1, an oscillation circuit 101 generates a signal having a predetermined frequency, and a frequency dividing circuit 102 divides the signal generated by the oscillation circuit 101 to generate a clock signal serving as a time reference, and a pulse down counter circuit 105 And output to the control circuit 103.
The control circuit 103 counts the clock signal and performs a time counting operation, and outputs a main driving pulse control signal to the main driving pulse generation circuit 104 so as to rotationally drive the stepping motor 109 every time a predetermined time is counted.

  As will be described later, the pulse down counter circuit 105 generates a pulse down signal for pulse down of the main drive pulse P1 when the predetermined pattern is continuously generated a predetermined number of times when driven by the main drive pulse P1. Output to the generation circuit 104. In response to the pulse down signal, the main drive pulse generation circuit 104 changes the main drive pulse P1 to the main drive pulse P1 down by one rank and outputs it to the motor drive circuit 106.

First, the control circuit 103 initializes the pulse rank n = 0 and the count value N = 0 of the pulse down counter 105 (step S400).
The control circuit 103 counts the clock signal from the frequency dividing circuit 102 and outputs the main drive pulse control signal to the main drive pulse generation circuit 104 when the second hand drive timing comes, and the main drive pulse P1n (in this case, n = 0) The main drive pulse generation circuit 104 is controlled so as to be driven at step S401. The main drive pulse generation circuit 104 selects the main drive pulse P10 in response to the main drive pulse control signal, and controls the motor drive circuit 106 to drive the stepping motor 109 by the main drive pulse P10. The motor drive circuit 106 drives the stepping motor 109 with the main drive pulse P10. When the stepping motor 109 rotates normally, the time hands (hour hand, minute hand, second hand) of the analog display unit 110 are driven.

Next, in the control circuit 103, the rotation detection circuit 107, and the detection section determination circuit 111, it is determined in which section T1 to T3 the induced signal VRs accompanying the rotation of the stepping motor 109 is generated (S402 to S404, S414).
That is, the rotation detection circuit 107 generates an induction signal VRs exceeding a predetermined reference threshold voltage Vcomp among the induction signals VRs generated by free vibration of the stepping motor 109 in the rotation detection period T immediately after driving the stepping motor 109. A detection signal is output to the detection section determination circuit 111 every time it is detected. The detection section determination circuit 111 determines which section the detection signal from the rotation detection circuit 107 belongs to, and notifies the control circuit 103 of the section to which the induced signal VRs exceeding the reference threshold voltage Vcomp belongs.

Based on the notification from the detection interval determination circuit 111, the control circuit 103 determines the pattern (the determination value of the first interval, the determination value of the second interval, the determination value of the third interval) of the induced signal VRs.
First, a case where a power supply voltage sufficient to drive the stepping motor 109 is obtained will be described. In this case, the pattern obtained by the notification from the detection section determination circuit 111 is (0, 1, 1/0) (steps S402 and S403). This state is a rotation with an appropriate margin for the stepping motor 109.

When the pattern (0, 1, 1/0) is obtained in process step S403, the control circuit 103 checks whether or not there is a voltage determination instruction (step S420). In this case, since a voltage determination instruction has not been issued, it is determined whether or not the pulse rank n is minimum (= 0) (step S422).
If the pulse rank n is the minimum, the control circuit 103 maintains the pulse rank n, returns to processing step S401, and waits for the next stepping motor drive timing (step S425).

If the pulse rank n is not the minimum in process step S422, 1 is added to the count value N of the pulse down counter 105 to set N = N + 1 (step S423).
The control circuit 103 determines whether or not the count value N of the pulse down counter 105 is N = predetermined value (for example, 160), and if it is not 160, maintains the pulse rank n and waits for the next stepping motor drive timing (step) S425).

If the count value N of the pulse down counter 105 is 160, the control circuit 103 clears the count value of the pulse down counter 105 and lowers the pulse rank by one (step S426).
The operations of the processing steps S424 and S425 are to reduce the pulse rank n at every constant count value (time) of the pulse down counter 105, thereby driving with the minimum pulse rank n and realizing power saving. There is N = 160 in this embodiment, but this value is arbitrary.

Next, when the pattern obtained by the determination of the detection section determination circuit 111 is (1, 1, 1/0) (steps S402 and S414), the rotation is slightly less for the stepping motor 109.
Here again, the control circuit 103 confirms whether or not there is a voltage determination instruction (step S415), and since no determination instruction has been issued, the control circuit 103 waits for the next drive timing while maintaining the pulse rank n (S419).

Next, when the pattern obtained from the determination result of the detection section determination circuit 111 becomes (1/0, 0, 1) (steps S402 to S404), the control circuit 103 rotates the stepping motor 109 but has a margin. There is no rotation. Here again, it is determined whether or not there is a voltage determination instruction (step S416). Since there is no voltage determination instruction yet, it is determined whether or not the pulse rank n is maximum (step S417).
If the pulse rank n is the maximum in process step S417, the control circuit 103 maintains the current pulse rank and waits for the next drive timing (step S419). If the pulse rank n is not the maximum, the rotation result has no margin at present, and it is necessary to raise the pulse rank n.

  Here, there are two factors that cause an unsatisfactory rotation result. One is when the train wheel load, which is the load of the stepping motor 109, temporarily increases, for example, when the calendar wheel is rotated. The other is that the voltage value of the drive power supply may have decreased with energy consumption. It is not yet possible to determine whether this is the case. Therefore, after giving the voltage determination instruction (step S412), the control circuit 103 stores the current pulse rank n of the main drive pulse P1n as rank data n0 in the storage unit in the control unit 103, and temporarily performs the main drive. The pulse P1 is set to the main drive pulse P1max having the highest rank, and the process returns to the processing step S401 (step S413).

If the pulse rank n is set to the maximum pulse rank max, if the load is temporarily increased, the next driving of the stepping motor 109 should be a rotation with an appropriate margin. This is because, at the system design stage, when the pulse rank n is maximized with respect to a possible load of the system, the drive pulse is designed so that the rotation has an appropriate margin. However, when the power supply voltage decreases, the drive energy is not sufficient even if the pulse rank n is set to the maximum pulse rank max, and the rotation does not have a moderate margin, and the marginal rotation without a margin or non-rotation Become.
Similarly, if the pattern based on the determination result of the detection section determination circuit 111 is (1/0, 0, 0) (steps S402 to S404), the control circuit 103 is non-rotating, so first the main drive pulse P1. It is forcibly rotated by being driven by the correction pulse P2 having a larger driving energy than that (S405).

Next, the control circuit 103 determines whether or not there is a voltage determination instruction (step S406), and next determines whether or not the pulse rank n is maximum because there is no voltage determination instruction (step S408). When the pulse rank n is the maximum, the control circuit 103 cannot increase the rank any more, and therefore returns the pulse rank n to the initial value 0 (steps S408 and S407).
If the pulse rank n is not maximum in process step S408, the control circuit 103 issues a voltage determination instruction in the same manner as described above (step S412), and the pulse rank n of the current main drive pulse P1n is stored in the storage unit in the control unit 103. The data is stored as rank data n0, the main drive pulse P1 is temporarily set to the main drive pulse P1max of the maximum rank, and the process returns to step S401 (step S413).

  In the above description, since a power supply voltage sufficient to drive the stepping motor 109 is obtained from the battery 112, a voltage determination instruction is issued when the pulse rank n is not maximum (steps S408, S417, and S412). The pattern based on the determination result of the detection section determination circuit 111 after driving when the pulse rank n is maximum is a pattern (0, 1, 1/0) indicating a rotation with a moderate margin or a margin of margin. It becomes a pattern (1, 1, 1/0) showing a little rotation.

When the pattern based on the determination result of the detection section determination circuit 111 is (0, 1, 1/0) in the processing steps S402 to S404 and S414, the control circuit 103 determines whether or not there is a voltage determination instruction in the processing step S420. Since there is a voltage determination instruction, the determination instruction is canceled, the pulse rank n of the main drive pulse P1 is returned to the rank n0 stored in the storage unit, and the process proceeds to processing step S411 (step S421). In this case, the control circuit 103 is required in the process (steps S408, S417, and S413) as a result of driving with the pulse rank n set to the maximum pulse rank max in the voltage determination instruction issued in process step S412 (step S413). It is determined that the rank increase is due to a temporary increase in the train wheel load of the stepping motor 109, and rank n is increased by one (S411).
Similarly, when the pattern based on the determination result of the detection section determination circuit 111 is (1, 1, 1/0) in the processing steps S402 to S404 and S414, the control circuit 103 determines whether there is a voltage determination instruction, Since there is a voltage determination instruction, the determination instruction is canceled, the pulse rank n of the main drive pulse P1 is returned to the rank n0 stored in the storage unit, and the process proceeds to processing step S411 (S415, S418).

Next, a case where a power supply voltage sufficient to drive the stepping motor 109 is not obtained from the battery 112 will be described.
When the power supply voltage of the battery 112 is gradually decreased to be lower than a predetermined value, it becomes difficult to drive the stepping motor 109 with a small pulse rank n. When the pattern based on the determination result of the detection determination circuit 111 indicates (1/0, 0, 1) (rotation with no margin) or (1/0, 0, 0) (non-rotation), the control circuit 103 ( That is, when the drive energy is insufficient, a voltage determination instruction is issued (step S412), and the drive pulse is a drive pulse having a predetermined drive energy (in this embodiment, the main drive pulse P1max having a pulse rank n of the maximum pulse rank max). ) (Step S413).
The voltage determination unit 103a of the control circuit 103 shows a pattern (1/0, 0, 1) or (1/0, 0, 0) even when the stepping motor 109 is driven by the main drive pulse P1max (step S402). To S404, S414), it is determined that the power supply voltage of the battery 112 is lower than a predetermined value.

  That is, if the load of the stepping motor 109 changes, the pattern of the induced signal VRs changes. Similarly, if the power supply voltage changes, it becomes equivalent to a state in which the load is changed in a pseudo manner, and according to the change of the power supply voltage. The pattern of the induced signal VRs representing the rotation state changes. For example, when the pattern of the induction signal VRs temporarily shows the driving energy maintenance pattern of the main driving pulse P1 or the driving energy rank-up pattern with the calendar load, the driving is induced by the main driving pulse P1max with the maximum driving energy. If the signal VRs is detected, the pattern of the induced signal VRs should indicate a sufficient rotational state. However, if the pattern of rank maintenance or rank up is shown without showing a sufficient rotational state, it can be determined that the power supply voltage has decreased below a predetermined value.

  That is, the voltage determination unit 103a of the control circuit 103 cancels the voltage determination instruction when the pattern of the induced signal VRs is a pattern indicating insufficient driving energy and there is a voltage determination instruction (steps S406 and S416), and the main drive After returning the pulse P1 to the rank n0 of the main drive pulse P1 stored in the storage unit (not shown) in the control circuit 103 (step S409), a warning that the voltage of the battery 112 has become a predetermined voltage or less is notified. (Step S410). Here, as the notification operation, the stepping motor 109 may be driven in a predetermined pattern. For example, in the case of an analog pointer watch, the voltage drop warning may be notified to the user by changing the second hand drive cycle from a normal 1 step / 1 second cycle to a 2 step / 2 second cycle. Good. Further, a separate notification unit may be provided and the notification unit may notify the user.

As described above, according to the stepping motor control circuit according to the present embodiment, any one of the plurality of main drive pulses P1 having different drive energies according to the rotation state detected by the rotation detection unit or each of the aforementioned Control means for driving the stepping motor 109 by selecting the correction drive pulse P2 having a drive energy larger than that of the main drive pulse P1, and the control means rotates the stepping motor 109 when the stepping motor 109 is driven by a predetermined drive pulse. The voltage of the power source is determined based on the rotation state of the stepping motor detected by the detecting means.
Therefore, it is possible to detect that the power supply voltage is out of the predetermined range without providing a voltage detection dedicated circuit such as a comparator circuit.

  In addition, according to the stepping motor control circuit according to the present embodiment, one of the plurality of main drive pulses P1 having different drive energy or the respective main drive pulses P1 depending on the rotation state detected by the rotation detection unit. And a control means for driving and controlling the stepping motor 109 by selecting the correction drive pulse P2 having a drive energy larger than the predetermined drive pulse (for example, the main drive pulse P1max of the maximum energy rank max or just before When the stepping motor 109 is driven by a main drive pulse P1) that is a predetermined rank number higher than the main drive pulse P1 that has been driven to 1), when the rotation detection means detects a lack of drive energy, the voltage of the power supply falls below a predetermined value It is configured to determine that it has been performed.

As described above, the pattern of the induction signal VRs indicating the rotation state of the stepping motor 109 is changed according to the change of the power supply voltage applied to the stepping motor 109, and the power supply voltage is detected in a pseudo manner based on the pattern. Like to do.
Therefore, it is possible to detect a drop in the power supply voltage without separately providing a voltage detection dedicated circuit such as a comparator circuit. Further, since it is not necessary to use a detection resistor that constitutes a comparator, power loss can be suppressed, and the area of the integrated circuit can be reduced and the size can be reduced.

Moreover, when using a primary battery as a power supply, it can be comprised so that battery replacement | exchange may be alert | reported, and when using a secondary battery, it can be comprised so that a charging operation may be prompted.
In addition, according to the analog electronic timepiece according to the present embodiment, the power supply voltage for driving the stepping motor can be detected without providing a circuit dedicated to voltage detection such as a comparator circuit, and it is possible to promote battery replacement. Become. Further, downsizing is possible.

In the present embodiment, when the pattern indicating the rotation state when driven by the main drive pulse P1max with the maximum drive energy is a pattern indicating insufficient drive energy, it is determined that the power supply voltage has decreased below a predetermined value. Although configured, it is configured to determine whether or not the power supply voltage has fallen below a predetermined value based on a pattern when the main driving pulse P1 driven immediately before is driven by the main driving pulse P1 that is upgraded by a predetermined number of ranks. May be.
In the present embodiment, the rotation detection period is divided into three sections, and the state of the power supply is determined based on the pattern of the induced signal VRs in the three sections. However, the rotation detection period is divided into a plurality of sections. The power supply state may be determined based on the pattern of the induced signal VRs in the plurality of sections.

FIG. 5 is a block diagram of an analog electronic timepiece using a stepping motor control circuit according to another embodiment of the present invention, which is an example of an analog electronic wristwatch. 5, the same parts as those in FIG. 1 are denoted by the same reference numerals.
In this other embodiment, a secondary battery 114 that is a power source of an analog electronic timepiece and functions as a power source of at least the stepping motor 109, a power generation unit that receives light and generates power to charge the secondary battery 114 or a charging unit A solar cell 113 and a switch 115 connected to the solar cell 113 are provided.

The switch 115 is an open / close switch made of, for example, a semiconductor element. The switch 115 is normally kept in an open state, and is configured to charge the secondary battery 114 with the electric power generated by the solar battery 113. When the secondary battery 114 exceeds the predetermined voltage and is overcharged, the switch 115 is closed by the control circuit 103, the solar battery 113 is short-circuited, and charging of the secondary battery 114 by the solar battery 113 is stopped.
Instead of the switch 115 for short-circuiting the solar battery 113, a switch is provided between the solar battery 113 and the secondary battery 114, and the switch is normally closed to charge the secondary battery 114 with the solar battery 113. In addition, the charging may be stopped by opening the secondary battery 114 when it is overcharged.

The detection interval determination circuit 111 detects the pattern of the induced signal VRs generated in the detection interval T having a plurality of intervals. In this embodiment, as shown in FIG. 6, the detection interval T includes four intervals T1a, It is divided into T1b, T2, and T3, and has a configuration in which the first section T1 in the embodiment is equally divided into a first section T1a in the first half and a second section T1b in the second half.
That is, in FIG. 6, the detection period T is divided into a first section T1a, a second section T1b, a third section T2, and a fourth section T3. The predetermined time immediately after driving by the main drive pulse P1 is the first interval T1a, the predetermined time after the first interval T1a is the second interval T1b, the predetermined time after the second interval T1b is the third interval T2, the third interval A predetermined time after the section T2 is set as a fourth section T3. In this way, the entire detection section T starting immediately after driving by the main drive pulse P1 is divided into a plurality of sections (four sections T1a to T3 in the present embodiment). In the other embodiments as well, there is no mask section that is a period in which the induced signal VRs is not detected.

When the XY coordinate space in which the main magnetic pole of the rotor 202 is located by rotation of the rotor 202 is divided into the first quadrant I to the fourth quadrant IV, the first section T1a to the fourth section T3 are expressed as follows. be able to.
That is, in a normal load state, when the voltage of the secondary battery 114 is a predetermined voltage (a voltage at which the stepping motor 109 has “reasonable rotation”), the first section T1a is a space around the rotor 202. In the second quadrant II, the section for determining the first forward rotation state of the rotor 202 and in the third quadrant III, the section for determining the first forward rotation state of the rotor 202, the second section T1b is the rotor 202 in the third quadrant III. The first section for determining the first forward rotation situation, the third section T2 is the section for determining the first forward rotation situation of the rotor 202 in the third quadrant III, the section for determining the first reverse rotation situation, the fourth section T3 is a section for determining the first reverse rotation state and the second forward rotation state of the rotor 202 in the third quadrant III.

  For example, in FIG. 6, in the stepping motor control circuit according to the other embodiment, in the normal load state, the secondary battery 114 is generated in the region a when the voltage is the “reasonable rotation” voltage. The induced signal VRs is detected in the first interval T1a, the induced signal VRs generated in the region b is detected in the first interval T1a, the second interval T1b, and the third interval T2, and the induced signal VRs generated in the region c is the third interval The induced signal VRs detected in the section T2 and the fourth section T3 and generated in the region d is detected in the fourth section T3.

Further, when the secondary battery 114 is in a normal load state and a voltage lower than the “moderate margin rotation” voltage by a predetermined value (a voltage at which the stepping motor 109 exhibits “a little margin rotation”), the region a Induced signal VRs generated in the first interval T1a and the second interval T1b is detected, and the induced signal VRs generated in the region b is detected in the second interval T1b and the third interval T2, and the induced signal VRs generated in the region c. Is detected in the third section T2 and the fourth section T3, and the induced signal VRs generated in the region d is detected in the fourth section T3.
Similarly, in the normal load state, the pattern of the induced signal VRs corresponding to the voltage of the secondary battery 114 is detected as shown in FIG. The control circuit 103 determines the main drive pulse according to the pattern of the induced signal VRs (the determination value of the first section T1a, the determination value of the second section T1b, the determination value of the third section T2, and the determination value of the fourth section T3). Various controls such as pulse control such as P1 rank up, rank maintenance, rank down, etc., and charge stop control of the secondary battery 114 are performed.

  Pattern (1/0, 0, 0, 0) (Pattern 1) shows the state in which the voltage of the secondary battery 114 is the lowest in the example of FIG. 6, and the state in which the stepping motor 109 did not rotate in this driving. Show. Since the stepping motor 109 did not rotate, the control circuit 103 forcibly rotates the stepping motor 109 by driving with the correction driving pulse P2, and the main driving pulse P1 is the main driving energy having one rank driving energy at the next driving. Pulse control is performed so that the driving pulse P1 is changed (ranked up) and driven.

In the pattern (1/0, 0, 1, 1) (pattern 2), the voltage of the secondary battery 114 is the second lowest after the pattern (1/0, 0, 0, 0). Although it rotated, it has shown that it is the rotation which has no allowance for drive energy at all. Since the control circuit 103 performs rotation with no margin at all, the control circuit 103 does not perform the drive with the correction drive pulse P2, but performs pulse control so that the main drive pulse P1 is driven up one rank at the next drive.
In the pattern (1/0, 0, 0, 1) (pattern 3), the voltage of the secondary battery 114 is the second lowest after the pattern (1/0, 0, 1, 1). Although it rotated, it has shown that it is a rotation which does not have a sufficient margin in drive energy. Since the control circuit 103 has a rotation that does not have a sufficient margin, the control circuit 103 does not perform the driving with the correction driving pulse P2, but performs the pulse control so that the main driving pulse P1 is driven up one rank in the next driving.

In the pattern (1, 0, 1, 1/0) (pattern 4), the voltage of the secondary battery 114 is the second lowest after the pattern (1/0, 0, 0, 1). Although it rotated, it has shown that it is a rotation with a little margin in drive energy. Since the control circuit 103 performs the rotation with a little margin, it does not drive with the correction drive pulse P2, and maintains the rank of the main drive pulse P1 without increasing the rank.
In the pattern (0, 0, 1, 0) (pattern 5), the voltage of the secondary battery 114 is the next lower than the pattern (1, 0, 1, 1/0), and the stepping motor 109 rotates in this driving. This shows that the drive energy is a moderate margin of rotation.

  In the pattern (0, 1, 1, 0) (pattern 6), the voltage of the secondary battery 114 is the next lower than the pattern (0, 0, 1, 0), and in this driving, the stepping motor 109 is rotated and driven. It shows that the rotation is a little more energy. In the case of the pattern (0, 0, 1, 0) and the pattern (0, 1, 1, 0), the control circuit 103 does not drive with the correction drive pulse P2, and does not increase the rank, and the main drive pulse P1. The main drive pulse P1 is lowered by one rank when a predetermined condition described later is satisfied.

Pattern (0, 1, 0, 0) (Pattern 7) indicates that the voltage of the secondary battery 114 is the highest, the stepping motor 109 is rotated by the current driving, and the driving energy has too much margin. ing. Since the control circuit 103 has too much room, the rank of the main drive pulse P1 is maintained without increasing the rank, and is lowered by one rank when a predetermined condition described later is satisfied.
7 and 8 are flowcharts showing the operation of another embodiment of the present invention.

Hereinafter, with reference to FIG. 5 to FIG. 8, parts different from the above-described embodiment will be described.
The control circuit 103 counts the clock signal from the frequency dividing circuit 102 and outputs the main drive pulse control signal to the main drive pulse generation circuit 104 and drives it with the main drive pulse P1n every time the second hand drive timing comes. The drive pulse generation circuit 104 is controlled (step S401). The main drive pulse generation circuit 104 selects the main drive pulse P1n in response to the main drive pulse control signal, and controls the motor drive circuit 106 to drive the stepping motor 109 by the main drive pulse P1n. The motor drive circuit 106 drives the stepping motor 109 with the main drive pulse P1n. When the stepping motor 109 rotates normally, the time hands (hour hand, minute hand, second hand) of the analog display unit 110 are driven.

Next, in the control circuit 103, the rotation detection circuit 107, and the detection section determination circuit 111, it is determined in which section T1a, T1b, T2, T3 the induced signal VRs accompanying the rotation of the stepping motor 109 is detected (step S701). ).
That is, the rotation detection circuit 107 generates an induction signal VRs exceeding a predetermined reference threshold voltage Vcomp among the induction signals VRs generated by free vibration of the stepping motor 109 in the rotation detection period T immediately after driving the stepping motor 109. A detection signal is output to the detection section determination circuit 111 every time it is detected. The detection section determination circuit 111 determines which section the detection signal from the rotation detection circuit 107 belongs to, and notifies the control circuit 103 of the section to which the induced signal VRs exceeding the reference threshold voltage Vcomp belongs. Based on the notification from the detection interval determination circuit 111, the control circuit 103 determines the pattern of the induced signal VRs (the determination value of the first interval, the determination value of the second interval, the determination value of the third interval, the determination value of the fourth interval). ).

When the control circuit 103 determines that the pattern obtained by the notification from the detection section determination circuit 111 is (1/0, 0, 0, 0) (pattern 1), the stepping motor 109 is non-rotating, so that correction driving is performed. After the correction drive pulse generation circuit 108 is controlled so as to be driven by the pulse P2 (step S405), the presence / absence of a voltage determination instruction is determined (step S406).
When the control circuit 103 determines that there is a voltage determination instruction in processing step S406, the control circuit 103 cancels the voltage determination instruction and stores the main drive pulse P1 in the storage unit (not shown) in the control circuit 103. After returning to rank n0 (step S702), control is performed so that a voltage drop instruction (for example, 2-second hand movement) is performed (step S410). In response to the control of the control circuit 103, the main drive pulse generation circuit 104 drives the stepping motor 109 through the motor drive circuit 106 so as to move the hands for 2 seconds. As a result, the analog display unit 110 moves the hands for 2 seconds, and notifies that the voltage of the secondary battery 114 has dropped below a predetermined value.

The control circuit 103 obtains (1/0, 0, 1, 1) (pattern 2) or (1/0, 0, 0, 1) (1) (pattern 2) by the notification from the detection section determination circuit 111 in the processing step S701. When it is determined as pattern 3), the process proceeds to processing step S416, and it is determined whether or not there is a voltage determination instruction.
If the control circuit 103 determines that there is a voltage determination instruction in processing step S416, the control circuit 103 proceeds to processing step S702 and performs the processing. If the control circuit 103 determines that there is no voltage determination instruction in process step S416, the control circuit 103 proceeds to process step S417 to determine whether or not the main drive pulse P1 is the main drive pulse P1max of the maximum rank and the subsequent processing. Do.

  If the control circuit 103 determines that the main drive pulse P1 is not the highest rank main drive pulse P1max in step S408, the control circuit 103 gives a voltage determination instruction (step S412), and then determines the pulse rank n of the current main drive pulse P1n. The data is stored in the storage unit in the control unit 103 as rank data n0, the main drive pulse P1 is temporarily set to the main drive pulse P1max of the maximum rank, and the process returns to step S401 (step S703).

If the control circuit 103 determines that the pattern obtained by the notification from the detection section determination circuit 111 is (1, 0, 1, 1/0) (pattern 4) in the processing step S701, the control circuit 103 proceeds to the processing step S415 and determines the voltage. The presence / absence of a determination instruction is determined.
When the control circuit 103 determines that there is a voltage determination instruction in processing step S415, the control circuit 103 cancels the voltage determination instruction, returns the pulse rank n of the main drive pulse P1 to the rank n0 stored in the storage unit, and proceeds to processing step S411. (Step S705). If the control circuit 103 determines that there is no voltage determination instruction in processing step S415, the control circuit 103 proceeds to processing step S419.

The control circuit 103 obtains (0, 0, 1, 0) (pattern 5) or (0, 1, 1, 0) (pattern 6) as a pattern obtained by the notification from the detection section determination circuit 111 in processing step S701. When it determines, it transfers to process step S420 and the presence or absence of a voltage determination instruction | indication is determined.
When determining that there is a voltage determination instruction in processing step S420, the control circuit 103 cancels the voltage determination instruction, returns the pulse rank n of the main drive pulse P1 to the rank n0 stored in the storage unit, and proceeds to processing step S411. (Step S704). If the control circuit 103 determines that there is no voltage determination instruction in processing step S420, the control circuit 103 proceeds to processing step S422 and performs the same processing as in the above embodiment.

When the control circuit 103 determines that the pattern obtained by the notification from the detection section determination circuit 111 is (0, 1, 0, 0) (pattern 7) in the processing step S701, the control circuit 103 proceeds to the processing step S706 and issues a voltage determination instruction. The presence or absence of is determined.
When the control circuit 103 determines that there is a voltage determination instruction in processing step S706, the control circuit 103 cancels the voltage determination instruction, returns the pulse rank n of the main drive pulse P1 to the rank n0 stored in the storage unit, and proceeds to processing step S411. (Step S709). If the control circuit 103 determines in step S706 that there is no voltage determination instruction, the control circuit 103 determines that the secondary battery 114 is in an overcharge state exceeding a predetermined voltage, and notifies the user of an instruction for overcharge. Further, by closing the switch 115, both terminals of the solar battery 113 are short-circuited to stop the charging of the secondary battery 114 (step S707).

  Next, the control circuit 103 sets the pulse rank n of the main drive pulse P1 to 0 and changes it to the main drive pulse P1min having the minimum energy (pulse width is minimum), and then returns to the processing step S401 (step S708). In this case, since the secondary battery 114 is overcharged, the voltage of the drive pulse becomes high, and the stepping motor 109 can be rotated even with the main drive pulse P1min having the minimum pulse width.

  Note that the control circuit 103 informs the user of an instruction for overcharge in the processing step S707 because the secondary battery 114 is in an overcharge state, or short-circuits both terminals of the solar battery 113 to You may make it perform at least one of stopping charging. Alternatively, the control circuit 103 may be configured to stop charging by opening the solar battery 113 and the secondary battery 114 together with at least one of them instead of these.

As described above, according to another embodiment of the present invention, a voltage determination instruction is issued in processing step S412, and when the driving is temporarily changed to the main driving pulse P1max of the maximum rank (step S703). When patterns 1, 2, and 3 are indicated (step S701), it is determined that the voltage of the secondary battery 114 has decreased to a predetermined value or less, and a voltage decrease instruction is issued (step S410).
Further, when the pattern 7 is displayed in the state where there is no voltage determination instruction (step S706) (step S701), the pattern 7 is displayed when driven by the main drive pulse that is not the main drive pulse P1max of the highest rank. The battery 114 is determined to be in an overcharged state, and is controlled to stop the charging of the secondary battery 114 by the solar battery 113.

Therefore, also in the other embodiments, the power supply voltage is in a predetermined range (for example, 1.2 V to 2.0 V which is an appropriate voltage range of the secondary battery 114) without providing a voltage detection dedicated circuit such as a comparator circuit. The effects similar to those of the above-described embodiment can be obtained, such as being able to detect the fact that they are outside.
In addition, according to the stepping motor control circuit according to the other embodiment, not only can the voltage of the secondary battery 113 be lowered to a predetermined voltage or less, but also an overcharged state can be obtained. It is possible to detect.
In addition, there is an effect that it is possible to notify the user of a voltage drop and overcharge of the secondary battery 114.

  In each of the above embodiments, the drive energy is changed by changing the pulse width using a rectangular wave drive pulse. However, a comb-like drive pulse is used, the pulse width is constant, and the duty is changed. The drive energy may be changed by changing the ratio, or the drive energy may be changed by changing the number of comb teeth while keeping the duty ratio constant (in this case, the pulse width is changed). Further, the driving energy may be changed by changing the pulse voltage.

In addition to the time hand, the present invention can be applied to a stepping motor for driving a calendar or the like.
Moreover, although the example of the electronic timepiece has been described as an application example of the stepping motor, it can be applied to an electronic device using the motor.

The stepping motor control circuit according to the present invention is applicable to various electronic devices that use the stepping motor.
The electronic timepiece according to the present invention can be applied to various analog electronic timepieces, including analog electronic timepieces with various calendar functions such as an analog electronic wristwatch with a calendar function and an analog electronic table clock with a calendar function.

DESCRIPTION OF SYMBOLS 101 ... Oscillator circuit 102 ... Frequency divider circuit 103 ... Control circuit 103a ... Voltage determination part 104 ... Main drive pulse generation circuit 105 ... Pulse down counter circuit 106 ... Motor drive circuit 107 ... rotation detection circuit 108 ... correction drive pulse generation circuit 109 ... stepping motor 110 ... analog display 111 ... detection section determination circuit 112 ... battery 113 ... solar battery 114 .. Secondary battery 115... Switch 201... Stator 202... Rotor 203... Rotor housing through-holes 204 and 205.
206, 207 ... Notch (outer notch)
208 ... Magnetic core 209 ... Coils 210, 211 ... Saturable portion OUT1 ... First terminal OUT2 ... Second terminal

Claims (11)

A power source for supplying power to at least the stepping motor;
Rotation detecting means for detecting the rotation state of the stepping motor;
The stepping motor is selected by selecting one of a plurality of main drive pulses having different drive energies or a correction drive pulse having a drive energy larger than each of the main drive pulses according to the rotation state detected by the rotation detection means. Control means for driving control,
The stepping motor control circuit, wherein the control means determines the voltage of the power source based on a rotation state of the stepping motor detected by the rotation detection means when the stepping motor is driven by a predetermined drive pulse.   The control means determines that the voltage of the power source has dropped below a predetermined value when the rotation detecting means detects a lack of drive energy when the stepping motor is driven by a predetermined drive pulse. Item 5. A stepping motor control circuit according to Item 1.   3. The control unit according to claim 1, wherein when the control unit determines that the voltage of the power source has decreased below a predetermined value, the control unit performs a notification operation indicating that the voltage of the power source has decreased below a predetermined value. Stepping motor control circuit.   The stepping motor control circuit according to claim 3, wherein the control means drives the stepping motor in a predetermined pattern as the notification operation.   5. The stepping motor control circuit according to claim 1, wherein the predetermined drive pulse is a main drive pulse obtained by increasing the rank of the main drive pulse driven immediately before by a predetermined rank number. 6.   5. The stepping motor control circuit according to claim 1, wherein the predetermined drive pulse is a main drive pulse with a maximum drive energy. The power source includes a secondary battery and charging means for charging the secondary battery,
The control means stops charging of the secondary battery by the charging means when the rotation detecting means detects overcharge of the secondary battery when the stepping motor is driven by a predetermined drive pulse. The stepping motor control circuit according to claim 1.   8. The stepping motor control circuit according to claim 1 or 7, wherein when the overcharge of the secondary battery is detected, the control means performs a notification operation indicating that the secondary battery is overcharged.   The rotation detection unit detects an induced signal generated by rotation of the stepping motor in a detection section divided into a plurality of sections, and detects a rotation state of the stepping motor based on a pattern of the section in which the induced signal is detected. The stepping motor control circuit according to claim 1, wherein the stepping motor control circuit is provided.   The stepping motor control circuit according to claim 9, wherein the detection section is divided into three sections or four sections. In an analog electronic timepiece having a stepping motor that rotationally drives a time hand and a stepping motor control circuit that controls the stepping motor,
An analog electronic timepiece using the stepping motor control circuit according to any one of claims 1 to 10 as the stepping motor control circuit.

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