JP2014096901A - Stepping motor control circuit, movement and analog electronic timepiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To implement accurate rotation detection and maintain durability by changing a braking force in accordance with whether or not the rotation of a stepping motor is easy to maintain.SOLUTION: A stepping motor control circuit includes: a battery 101 as a power supply; a voltage detection circuit 107 for detecting a voltage of the battery 101; a rotation detection section for detecting a rotational status of a stepping motor 103; and a control section for rotatively driving the stepping motor 103 by selecting a driving pulse depending on the rotational status detected by the rotation detection section. The rotation detection section detects a rotation with the use of a smaller braking force to the stepping motor 103 if the voltage of the battery 101 detected by the voltage detection circuit 107 does not exceed a predetermined value than if it is exceeded.

Description

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

  Conventionally, when detecting rotation of a stepping motor in an analog electronic timepiece, in a detection period immediately after driving the stepping motor with a main drive pulse P1, a first closed circuit including a driving coil of the stepping motor and a detection resistor Rs; By alternately configuring the second closed circuit formed by short-circuiting the drive coil with a low impedance element, amplifying the induced signal VRs generated by the free vibration of the stepping motor and detecting it by the detection resistor Rs, A rotation detection method for detecting the rotation state of the stepping motor is employed.

Depending on the voltage fluctuation of the battery used as the power source, the difference in the weight of the time hand used, the presence of a magnetic field, etc., whether or not it is easy to maintain the rotation of the stepping motor will fluctuate, causing a malfunction in driving the stepping motor there is a possibility. For example, the rotation of the stepping motor can be accurately detected even in a state in which the rotation of the stepping motor is easily maintained (for example, a state where the battery voltage is high, a state where a heavy (large) time hand is used, or a magnetic field is present). In addition, it is configured to ensure a sufficient braking force of the rotor of the stepping motor.
However, when the braking force is large, there is a problem in that the side pressure of the rotating shaft of the rotor and the bearing portion becomes high, so that wear tends to occur and the durability is poor. If the braking force is reduced to prevent this problem, it may be erroneously detected that the stepping motor has rotated even though it has not rotated, and accurate rotation drive may not be possible.

  Although Patent Document 1 describes an invention in which the period of a detection pulse is partially shortened, the invention described in Patent Document 1 detects rotation so that the rotation decay time of the stepping motor does not become long. Therefore, the cycle of the detection pulse is shortened, and is not intended to suppress erroneous rotation detection due to fluctuations in the power supply voltage or the like.

JP 2009-288133 A

  The present invention has been made in view of the above problems, and by changing the braking force according to whether or not the rotation of the stepping motor is easy to maintain, the rotation can be accurately detected and the durability can be improved. The challenge is to maintain.

  According to a first aspect of the present invention, a battery as a power source, a voltage detection unit that detects a voltage of the battery, a rotation detection unit that detects a rotation state of a stepping motor, and a rotation detected by the rotation detection unit A control unit that rotationally drives the stepping motor by selecting a driving pulse according to a situation, and the rotation detection unit exceeds when the voltage of the battery detected by the voltage detection unit exceeds a predetermined value. A stepping motor control circuit is provided that detects rotation by increasing the braking force of the stepping motor as compared with the case where there is no stepping motor.

  According to a second aspect of the present invention, a battery as a power source, a voltage detection unit that detects a voltage of the battery, a rotation detection unit that detects a rotation state of a stepping motor, and a rotation detected by the rotation detection unit A control unit that rotationally drives the stepping motor by selecting a driving pulse according to a situation, and the rotation detection unit is configured to detect when the voltage of the battery detected by the voltage detection unit does not exceed a predetermined value. A stepping motor control circuit is provided that detects rotation by making the braking force of the stepping motor smaller than when exceeding.

  According to a third aspect of the present invention, there is provided a movement comprising any one of the above stepping motor control circuits.

  According to a fourth aspect of the present invention, there is provided an analog electronic timepiece comprising the movement.

According to the stepping motor control circuit of the present invention, it is possible to accurately detect the rotation and maintain the durability by changing the braking force according to whether or not the rotation of the stepping motor is easily maintained. Is possible.
According to the movement of the present invention, an analog capable of accurately detecting rotation and maintaining durability by changing the braking force according to whether or not the rotation of the stepping motor is easily maintained. It is possible to construct an electronic clock.
Further, according to the analog electronic timepiece according to the invention, it is possible to accurately detect the rotation and maintain the durability by changing the braking force according to whether or not the rotation of the stepping motor is easily maintained. Therefore, accurate hand movement is possible and the life can be extended.

1 is a block diagram of a stepping motor control circuit, a movement, and an analog electronic timepiece according to a first embodiment of the invention. It is a block diagram of a stepping motor control circuit, a movement, and an analog electronic timepiece according to a second embodiment of the present invention. It is a block diagram of the stepping motor used in each embodiment of the present invention. It is a partial detailed circuit diagram common to each embodiment of the present invention. It is a timing diagram common to each embodiment of this invention. It is a timing diagram common to each embodiment of this invention. It is a timing diagram common to each embodiment of this invention. It is a timing diagram common to each embodiment of this invention. It is a timing diagram common to each embodiment of this invention. It is explanatory drawing in each embodiment of this invention. It is explanatory drawing in each embodiment of this invention. It is explanatory drawing in each embodiment of this invention.

FIG. 1 is a block diagram of a stepping motor control circuit, a movement, and an analog electronic timepiece according to the first embodiment of the present invention, and shows an example of an analog electronic wristwatch.
In FIG. 1, the analog electronic timepiece includes a battery 101 as a power source, a stepping motor control circuit 102, a stepping motor 103, and a timepiece case 115.
Further, the analog electronic timepiece is disposed on the outer surface side of the timepiece case 115, and is an analog having a time hand (hour hand, minute hand, second hand) 118 and a calendar display unit 119 which are rotationally driven by the stepping motor 103 to display time and date. A display unit 116 and a movement 117 disposed inside the watch case 115 are provided.

  The stepping motor control circuit 102 constitutes an oscillation circuit 104 that generates a signal of a predetermined frequency, a frequency division circuit 105 that divides the signal generated by the oscillation circuit 104 and generates a clock signal that is a reference for timekeeping, and an analog electronic timepiece Control circuit 106 for controlling each electronic circuit element to be controlled, control for changing drive pulses (pulse control), etc., and main drive pulse control from control circuit 106 among a plurality of types of main drive pulses P1 having different energy In response to the correction drive pulse control signal from the main drive pulse generation circuit 109 and the control circuit 106 that selects and outputs the main drive pulse P1 corresponding to the signal, the correction drive pulse P2 having energy larger than each of the main drive pulses P1 is output. A correction drive pulse generation circuit 110 for outputting is provided.

  One main drive pulse P1 may be used as the main drive pulse P1, and in this case, the control circuit 106 outputs the main drive pulse control signal or the correction drive pulse P2 that instructs the output of the main drive pulse P1. Is output to the main drive pulse generation circuit 109 or the correction drive pulse generation circuit 110. The main drive pulse generation circuit 109 and the correction drive pulse generation circuit 110 output the main drive pulse P1 and the correction drive pulse P2 in response to the main drive pulse control signal and the correction drive pulse control signal.

The stepping motor control circuit 102 includes a motor drive circuit 111 that drives the stepping motor 103 by the main drive pulse P1 and the correction drive pulse P2 from the main drive pulse generation circuit 109 and the correction drive pulse generation circuit 110.
The stepping motor control circuit 102 detects an induced signal VRs generated by free vibration of the rotor of the stepping motor 103 and exceeding a predetermined reference threshold voltage Vcomp in a predetermined detection period T, and an induced signal VRs exceeding the reference threshold voltage Vcomp. Is provided with a rotation detection circuit 114 that outputs a rotation detection signal Vs indicating whether or not is detected.

  When the rotational operation of the rotor is fast, such as when the stepping motor 103 rotates, an induced signal VRs exceeding a predetermined reference threshold voltage Vcomp is generated, and the rotor as in the case where the stepping motor 103 does not rotate. The reference threshold voltage Vcomp is set so that the induced signal VRs does not exceed the reference threshold voltage Vcomp when the rotation operation is slow.

The induced signal VRs is a signal representing the rotation state of the stepping motor 103, and the rotation detection signal Vs is also a signal representing the rotation state.
The control circuit 106 generates a main drive pulse control signal or a correction drive pulse control signal so as to be driven by the main drive pulse P1 or the correction drive pulse P2 of energy corresponding to the rotation state detected by the rotation detection circuit 114. The signal is output to the circuit 109 or the correction drive pulse generation circuit 110.

The stepping motor control circuit 102 determines the detection time of the induced signal VRs by comparing the time when the rotation detection circuit 114 detects the induced signal VRs exceeding the reference threshold voltage Vcomp with a predetermined reference threshold time tcomp. In addition, an induction signal (VRs) output time comparison circuit 113 that outputs a rotation detection signal Vs representing a rotation state is provided.
Further, the stepping motor control circuit 102 controls the rotation detection operation of the rotation detection circuit 114 according to the voltage detection circuit 107 that detects the voltage (battery voltage) of the battery 101 and the battery voltage of the battery 101 detected by the voltage detection circuit 107. A rotation detection control circuit 112 is provided for outputting a rotation detection control signal. The rotation detection circuit 114 performs a rotation detection operation in response to the rotation detection control signal while changing the magnitude of the braking force of the stepping motor 103.

  The rotation detection circuit 114 includes a first time that forms a first closed circuit including a drive coil of the stepping motor 103 and a detection element that detects the induced signal VRs generated by the stepping motor 103, and a second that short-circuits the drive coil. The rotation state of the stepping motor 103 is detected in a detection section DT having a plurality of periods formed by the second time forming the closed circuit. A detection cycle (in other words, a sampling pulse generation cycle) is configured by the first time and the second time, and the detection interval DT is configured by a plurality of detection cycles in which the first time and the second time are alternately repeated.

  Although details will be described later, in each embodiment of the present invention, the rotation detection circuit 114 is configured by forming the first closed circuit and the second closed circuit as a method of changing the magnitude of the braking force of the stepping motor 103. Either the method of changing the start time or end time of the sampling pulse to be used, the method of changing the ratio of the first time to the second time (related to the duty ratio of the sampling pulse), or the method of changing the cycle of the sampling pulse doing.

Battery 101, stepping motor 103, oscillation circuit 104, frequency divider circuit 105, control circuit 106, voltage detection circuit 107, main drive pulse generation circuit 109, correction drive pulse generation circuit 110, motor drive circuit 111, rotation detection control circuit 112, The induced signal output time comparison circuit 113 and the rotation detection circuit 114 are components of the movement 117.
In general, a timepiece mechanical body composed of devices such as a timepiece power source and a time reference is called a movement. Electronic devices are sometimes called modules. When the watch is completed, a dial and hands are attached to the movement and housed in a watch case.

  Here, the oscillation circuit 104 and the frequency dividing circuit 105 constitute a signal generation unit, and the analog display unit 116 constitutes a display unit. The rotation detection circuit 114 and the induced signal output time comparison circuit 113 constitute a rotation detection unit. The oscillation circuit 104, the frequency dividing circuit 105, the control circuit 106, the main drive pulse generation circuit 109, the correction drive pulse generation circuit 110, the motor drive circuit 111, and the rotation detection control circuit 112 constitute a control unit. The control circuit 106 and the rotation detection control circuit 112 constitute a braking force control unit.

FIG. 3 is a configuration diagram of the stepping motor 103 used in each embodiment of the present invention, and shows an example of a timepiece stepping motor generally used in an analog electronic timepiece.
In FIG. 3, a stepping motor 103 includes 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 winding around the magnetic core 208. A rotated drive coil 209 is provided. When the stepping motor 103 is used in an analog electronic timepiece, the stator 201 and the magnetic core 208 are fixed to a base plate (not shown) with screws (not shown) and joined to each other. The drive 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 so as not to be magnetically saturated by the magnetic flux of the rotor 202 but to be magnetically saturated when the drive 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. When the drive coil 209 is not excited, the rotor 202 is positioned corresponding to the positioning portion as shown in FIG. 3, in other words, the magnetic pole axis A of the rotor 202 is a line connecting the notches 204 and 205. It is stably stopped at a position orthogonal to the minute (position where the angle between the magnetic pole axis A and the X axis is θ0).

  Now, a rectangular-wave drive pulse is supplied from the motor drive circuit 111 between the terminals OUT1 and OUT2 of the drive coil 209 (for example, the first terminal OUT1 side is positive and the second terminal OUT2 side is negative), and the arrow in FIG. When a current i flows in the direction, a magnetic flux is generated in the stator 201 in the direction of the broken arrow. As a result, the saturable portions 210 and 211 are saturated and the magnetic resistance increases, and then the rotor 202 rotates 180 degrees in the direction of the arrow in FIG. 3 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. 3) for causing the normal operation (in this embodiment, since it is an analog electronic timepiece to move the hand) by rotating the stepping motor 103 is defined as a positive direction. The reverse (clockwise direction) is the reverse direction.

Next, a rectangular-wave drive pulse having a reverse polarity is supplied from the motor drive circuit 111 to the terminals OUT1 and OUT2 of the drive coil 209 (the first terminal OUT1 side has a negative polarity so that the polarity is opposite to that of the drive). When the second terminal OUT2 side is the positive electrode) and a current is passed in the direction indicated by the arrow in FIG. Thereby, the saturable portions 210 and 211 are first saturated, and then the rotor 202 rotates 180 degrees in the same direction (positive direction) as described above due to the interaction between the magnetic pole generated in the stator 201 and the magnetic pole of the rotor 202. The magnetic pole axis A stably stops at the angle θ0 position.
Thereafter, by supplying signals with different polarities (alternating signals) to the drive 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 to be able to.

FIG. 4 is a partial detailed circuit diagram of each embodiment of the present invention, and is a partial detailed circuit diagram of the main drive pulse generation circuit 109, the correction drive pulse generation circuit 110, the motor drive circuit 111, and the rotation detection circuit 114.
The switch control circuit 303 responds to the control signal Vi supplied from the control circuit 106 at the time of rotational driving, by simultaneously turning on the transistors Q2 and Q3, or by simultaneously turning on the transistors Q1 and Q4. A drive current is supplied to the drive coil 209 in the forward direction or the reverse direction, thereby rotating the stepping motor 103.

In addition, the switch control circuit 303 is one of switching states in which the transistors Q3 to Q6 are turned on, turned off, and turned on and off (on / off state) alternately at a predetermined cycle (detection cycle) when rotation is detected. And the induced signal VRs is controlled to be generated in the detection resistor 301 or 302.
When the induced signal VRs exceeding the predetermined reference threshold voltage Vcomp is generated in the detection resistor 301 or 302, the comparator 304 outputs the rotation detection signal Vs at that time.

The transistors Q1 and Q2 are components of the motor drive circuit 111, and the transistors Q5 and Q6 and the detection resistors 301 and 302 are components of the rotation detection circuit 114. The transistors Q3 and Q4 are components that are used as both the motor drive circuit 111 and the rotation detection circuit 114.
The detection resistors 301 and 302 are elements having the same resistance value, and constitute detection elements. The detection resistors 301 and 302 have a high resistance value and constitute a high impedance element. The transistors Q1 to Q6 are elements that have a small on-resistance and are substantially short-circuited in the on state, and constitute a low impedance element.

5 to 9 are timing diagrams common to the respective embodiments of the present invention.
FIG. 5 is a timing diagram in a state in which the rotation of the stepping motor 103 is easily maintained. The rotation detection circuit 114 has a function of the stepping motor 103 compared to the state in which the rotation of the stepping motor 103 in FIGS. Rotation is detected while applying a large braking force.
6 to 9 are timing diagrams in a state in which it is difficult to maintain the rotation of the stepping motor 103. The rotation detection circuit 114 detects rotation by making the braking force applied to the stepping motor 103 smaller than that in the case of FIG. In each embodiment of the present invention, the operation of any one of FIGS. 6 to 9 is performed in order to change the braking force, and the function of performing any one operation of FIGS. 6 to 9 may be provided. That's fine.
5 to 9 show the operation timing when rotating with one polarity (OUT1 or OUT2), and the operation timing when rotating with the other polarity (OUT2 or OUT1) is omitted. Yes.

  Further, in the embodiment of the present invention, whether or not the rotation of the stepping motor 103 is easily maintained is determined based on whether the battery voltage of the battery 101 used as a power source is high or low, and an external magnetic field exceeding a predetermined strength (even a DC magnetic field). Examples of the presence or absence of the AC magnetic field and the lightness of the time hand to be used (load size) are given. When the battery voltage of the battery 101 used as a power source exceeds a predetermined value, when there is an external magnetic field where the battery voltage of the battery 101 exceeds a predetermined value and exceeds a predetermined intensity, and when the time hand to be used has a predetermined weight When exceeding, it is in a state where it is easy to rotate or has a large inertia and it is easy to maintain the rotation of the stepping motor 103. Conversely, when the battery voltage of the battery 101 does not exceed the predetermined value, when at least one of the battery voltage of the battery 101 and the strength of the external magnetic field does not exceed the predetermined value, and when the time hand to be used does not exceed the predetermined weight Is in a state in which it is difficult to rotate or in which inertia is small, and it is difficult to maintain the rotation of the stepping motor 103.

  In FIG. 5, when the stepping motor 103 is rotationally driven with the main drive pulse P1, the transistors Q2 and Q3 are switched to be turned on / off at a predetermined period between times t1 and t2, which is a driving period, thereby generating a comb. A tooth-shaped main drive pulse P1 is generated, and a drive current i in the direction of the arrow is supplied to the drive coil 209 of the stepping motor 103 by the main drive pulse P1. Thereby, when the stepping motor 103 rotates, the rotor 202 rotates 180 degrees in the forward direction.

  On the other hand, a mask section IT is provided from time t2 to time t3 when the driving of the main drive pulse P1 is completed, and a detection section DT is provided from time t3 to time t4 following the mask section IT. A detection period T from time t2 to time t4 is configured by the mask section IT and the detection section DT. The mask section IT is a period for preventing erroneous determination of the rotation state due to noise or the like immediately after driving the main drive pulse P1, and the control circuit 106 uses the induced signal VRs generated during this period as information for determining the rotation state. Are not used, in other words, the mask section IT is a period during which no rotation is detected.

  The detection section DT includes a plurality of sampling pulses that repeat at a predetermined cycle (detection cycle). The detection period of the sampling pulse includes a first time when the detection resistor 301 or 302 is connected in series with the drive coil 209 to form a first closed circuit, and the drive coil 209 without connecting the detection resistor 301 or 302 to the drive coil 209. Is short-circuited by a low impedance element to form a second closed circuit.

  When the stepping motor 103 is in a state where it is easy to maintain the rotation, as shown in FIG. 5, in the mask section IT, the transistors Q2 and Q6 are driven to the off state and the transistors Q3 and Q4 are driven to the on state. In the detection period DT after the lapse of the mask period IT, the transistor Q2 is turned off, the transistor Q3 is turned on, the transistor Q4 is turned on / off repeatedly in the detection cycle, and the transistor Q6 is driven to the on state. The driving coil 209 is short-circuited by the second closed circuit during the second time when the transistor Q4 is on, and a large braking force is applied to the stepping motor 103, and the driving coil is applied during the first time when the transistor Q4 is off. Since the detection resistor 302 forms a first closed circuit together with 209, a small braking force is applied to the stepping motor 103.

  In the case where it is difficult to maintain the rotation of the stepping motor 103, in the example of FIG. 6, the first closed circuit and the second closed circuit are alternated in the mask section IT provided immediately after the main drive pulse P1 is driven in the detection period T. The braking force of the stepping motor 103 is changed depending on whether or not it is formed. When the rotation detection circuit 114 detects rotation by reducing the braking force of the stepping motor 103, the rotation detection operation is performed by performing an operation of alternately forming the first closed circuit and the second closed circuit in the mask section IT.

  That is, when it is difficult to maintain the rotation of the stepping motor 103, in the example of FIG. 6, the transistor Q4 is switched to the on / off state in the detection period within the mask interval IT. As a result, the first time for forming the first closed circuit including the detection resistor 302 in the mask section IT is increased, so that the braking force of the stepping motor 103 is reduced. Thus, the rotation detection operation is performed in the detection section DT while weakening the braking force.

  In the example of FIG. 7, the braking force of the stepping motor 103 is changed by changing the end timing of the detection period T (in other words, the detection section DT). The rotation detection circuit 114 delays the end time of the detection period T when detecting rotation by reducing the braking force of the stepping motor 103. That is, in FIG. 7, the switching operation of the transistor Q4 is terminated later than in the case of FIG. As a result, the first time for forming the first closed circuit in the detection section DT becomes longer, and the braking force of the stepping motor 103 becomes smaller. Thus, the rotation detection operation is performed in the detection section DT while weakening the braking force.

  In the example of FIG. 8, the braking force of the stepping motor 103 is changed by changing the ratio between the first time and the second time. The rotation detection circuit 114 increases the value of (first time / second time) when detecting the rotation by reducing the braking force of the stepping motor 103. That is, in FIG. 8, the value of (first time / second time) is made larger than in the case of FIG. As a result, the first time for forming the first closed circuit in the detection section DT becomes longer, and the braking force of the stepping motor 103 becomes smaller. Thus, the rotation detection operation is performed in the detection section DT while weakening the braking force.

  In the example of FIG. 9, the braking force of the stepping motor 103 is changed by changing the detection cycle. The rotation detection circuit 114 lengthens the detection cycle when detecting the rotation by reducing the braking force of the stepping motor 103. That is, in FIG. 9, the detection cycle is made longer than in the case of FIG. As a result, the value of (first time / second time) does not change, but since the interval at which the first closed circuit is formed in the detection interval DT becomes longer, the braking is not performed every moment, and as a result, stepping is performed. The braking force of the motor 103 is reduced. Thus, the rotation detection operation is performed in the detection section DT while weakening the braking force.

The comparator 304 compares the induced signal VRs generated in the detection resistor 302 with a predetermined reference threshold voltage Vcomp, and detects the induced signal VRs exceeding the reference threshold voltage Vcomp, and sends the rotation detection signal Vs to the control circuit 106. Output.
The induced signal output time comparison circuit 113 compares the time at which the rotation detection circuit 114 detects the induced signal VRs exceeding the reference threshold voltage Vcomp with a predetermined reference threshold time tcomp to determine whether the stepping motor 103 has rotated. Rotation detection signal Vs representing (rotation state) is output to control circuit 106.

  The control circuit 106 determines the rotation state of the stepping motor 103 based on the rotation detection signal Vs from the induced signal output time comparison circuit 113, and changes to the main drive pulse P1 having a large one-rank energy at the next drive and drives. (Pulse up), pulse control is performed such that the main drive pulse P1 having a low energy of one rank is changed and driven (pulse down), and the drive with the correction drive pulse P2 is performed at the next drive.

After the above-described cycle ends, the transistors Q1 to Q6 are driven and controlled so that the same operation is performed in the next cycle.
However, in the next cycle, instead of the transistors Q2 and Q3, the transistors Q1 and Q4 are switched to the on / off state at a predetermined cycle, and driven by the comb-like main drive pulse P1.

In the mask section IT and the detection section DT, the transistor Q3 is driven to the on state, the off state, or the switching state at the same timing as the transistor Q4 instead of the transistor Q4. Further, instead of the transistor Q6, the transistor Q5 is driven to the on state or the off state at the same timing as the transistor Q6.
An induced signal VRs generated by the rotation of the stepping motor 103 is generated in the detection resistor 301. When the comparator 304 detects the induced signal VRs exceeding the reference threshold voltage Vcomp, the comparator 304 outputs the detection signal Vs.

The induced signal output time comparison circuit 113 compares the time when the rotation detection circuit 114 detects the induced signal VRs exceeding the reference threshold voltage Vcomp with a predetermined reference threshold time tcomp, and represents the rotation state of the stepping motor 103. The detection signal Vs is output to the control circuit 106.
The control circuit 106 performs the same pulse control as described above based on the detection signal Vs from the induced signal output time comparison circuit 113.

By alternately repeating the two cycles, the rotation of the stepping motor 103 is controlled, the time hand 118 is driven, and the current date and time is displayed on the display unit 116.
When the stepping motor 103 does not rotate despite being driven by the main drive pulse P1, the correction drive pulse P2 is driven. In this case, the rotation detection operation is not performed.

  FIG. 10 is a timing diagram illustrating how the induced signal VRs varies when the battery voltage of the battery 101 varies in each embodiment. The induced signal VRs exceeding the reference threshold voltage Vcomp is generated earlier when the battery voltage is higher than when the battery voltage is low. The degree of energy margin of the main drive pulse P1 can be determined based on whether or not the induced signal VRs exceeding the reference threshold voltage Vcomp is detected earlier than the reference threshold time tcomp.

  As a result, the control circuit 106 determines the margin of the main drive pulse P1 based on the comparison result between the detection time of the induced signal VRs exceeding the reference threshold voltage Vcomp by the induced signal output time comparison circuit 113 and the reference threshold time tcomp. The degree can be determined and control can be performed to change the energy of the main drive pulse P1. When the battery voltage fluctuates, there is no temporal difference in the induced signal VRs detected as a result of driving with the two polarities OUT1 and OUT2.

FIG. 11 is a timing diagram illustrating how the induced signal VRs varies when the external magnetic field varies in each embodiment. When a magnetic field exceeding a predetermined intensity is generated, the generation timing of the induced signal VRs fluctuates due to the influence.
When there is no magnetic field exceeding the predetermined intensity, there is no temporal difference in the induced signal VRs detected as a result of driving with the two polarities OUT1 and OUT2.

  However, when a magnetic field exceeding a predetermined intensity exists, there is a temporal difference between the induced signals VRs generated as a result of driving with the two polarities OUT1 and OUT2. The control circuit 106 is based on the comparison result between the time when the induced signal output time comparison circuit 113 detects the induced signal VRs exceeding the reference threshold voltage Vcomp and the reference threshold time tcomp when driven by the bipolar polarity OUT1 and OUT2. Thus, it is possible to determine whether or not there is a magnetic field exceeding a predetermined intensity and to control to change the energy of the main drive pulse P1.

  FIG. 12 is a timing diagram showing how the induced signal VRs varies when the load such as the weight of the time hand varies in each embodiment. Since the rotation is faster when the load is smaller than when the load is large, the induced signal VRs exceeding the reference threshold voltage Vcomp is generated earlier. The degree of energy margin of the main drive pulse P1 with respect to the load can be determined based on whether or not the detection is performed earlier than the reference threshold time tcomp included in the induced signal output time comparison circuit 113. Thus, the control circuit 106 determines the margin of the main drive pulse P1 with respect to the load based on the comparison result between the detection time of the induction signal VRs and the reference threshold time tcomp by the induction signal output time comparison circuit 113, It can be controlled to change the energy of the main drive pulse P1.

  Even when the battery voltage fluctuates, there is no temporal difference in the induced signals VRs detected as a result of driving with the two polarities OUT1 and OUT2 as in the case of the load fluctuating, so the reference threshold voltage Vcomp is Only from the comparison result between the induced signal VRs exceeding the reference threshold time tcomp, it cannot be determined which of the battery voltage and the load has changed. However, it can be determined whether or not there is a load fluctuation by referring to the detection result of the voltage detection circuit 107.

Hereinafter, the operation of the first embodiment of the present invention will be described in detail with reference to FIGS. 1 and 3 to 9.
The control circuit 106 counts the clock signal from the frequency dividing circuit 105 and outputs a main drive pulse control signal to the main drive pulse generation circuit 109 at a predetermined cycle. The main drive pulse generation circuit 109 outputs, to the motor drive circuit 111, a main drive pulse P1 having energy corresponding to the main drive pulse control signal from among a plurality of types of main drive pulses P1 having different energy.

The motor drive circuit 111 drives the stepping motor 103 by the main drive pulse P1. The stepping motor 103 rotationally drives the time hand 118 and the calendar display unit 119. When the stepping motor 103 rotates normally, the hour hand 118 is moved and the date display operation of the calendar display unit 119 is performed at a predetermined timing.
The voltage detection circuit 107 detects the battery voltage of the battery 101 at a predetermined timing. When the battery voltage exceeds the predetermined voltage, the rotation detection circuit 114 performs the rotation detection operation of the stepping motor 103 at the timing of FIG. .

That is, when the battery voltage detected by the voltage detection circuit 107 exceeds a predetermined value, the control circuit 106 causes the battery voltage of the battery 101 to exceed a predetermined value (in other words, in a state in which the rotation of the stepping motor 103 is easily maintained). A voltage detection signal indicating that there is) is output to the rotation detection control circuit 112. The rotation detection control circuit 112 outputs a rotation detection control signal to the rotation detection circuit 114 in response to a voltage detection signal indicating that the battery voltage exceeds a predetermined value, and rotates to detect rotation with a large braking force. The detection circuit 114 is controlled.
In response to the rotation detection control signal, the rotation detection circuit 114 performs a rotation detection operation with a large braking force at the timing shown in FIG.

  The rotation drive operation and the rotation detection operation will be further described with reference to FIGS. 1 and 3 to 5. The control circuit 106 counts the clock signal from the frequency divider circuit 105, and at time t 1, The control signal Vi is output to the main drive pulse generation circuit 109 so that the stepping motor 103 is driven by the main drive pulse P1 of which the first terminal OUT1 side is positive and the second terminal OUT2 side is negative.

The main drive pulse generation circuit 109 drives the stepping motor 103 with the main drive pulse P1 having energy corresponding to the control signal Vi (here, the first terminal OUT1 side is positive and the second terminal OUT2 side is negative). To do.
In this case, the switch control circuit 303 responds to the control signal Vi with the comb-like main drive pulse P1 generated by switching the transistors Q2 and Q3 between the on state and the off state at a predetermined cycle, and the stepping motor 103 Drive.
When the stepping motor 103 is driven, an induced signal VRs corresponding to the rotation state is generated.
At time t2, the driving of the stepping motor 103 is stopped. The rotation detection circuit 114 maintains the transistors Q2 and Q6 in the off state and the transistors Q3 and Q4 in the on state during the mask period IT from time t2 to time t3.

When the mask section IT has elapsed, the rotation detection circuit 114 detects the induced signal VRs exceeding the reference threshold voltage Vcomp in the detection section DT starting from time t3. In the rotation detection operation in this case, the transistors Q2 and Q3 perform the same operation as in the mask section IT, the transistor Q6 is switched on and the transistor Q4 is switched to the on / off state at a predetermined cycle.
In the rotation detection circuit 114, when the detection interval DT elapses, the transistors Q2 and Q3 perform the same operation as the detection interval DT after the time t4, and the transistor Q4 is turned on and the transistor Q6 is turned off.

Accordingly, a braking force is applied to the stepping motor 103 during the first time when the first closed circuit is configured, and as a result, the rotation detection operation is performed in a state where a large braking force is applied.
The induced signal output time comparison circuit 113 compares the time when the rotation detection circuit 114 detects the induced signal VRs exceeding the reference threshold voltage Vcomp with the reference threshold time tcomp, and uses the control signal 106 to detect the detection signal Vs representing the rotation state. Output to. The control circuit 106 rotationally drives the stepping motor 103 while performing the above-described pulse control operation based on the rotation detection signal Vs.

On the other hand, when the battery voltage detected by the voltage detection circuit 107 does not exceed the predetermined value, the control circuit 106 does not exceed the predetermined value (in other words, it is difficult to maintain the rotation of the stepping motor 103). A voltage detection signal indicating that the rotation is detected) is output to the rotation detection control circuit 112. The rotation detection control circuit 112 outputs a rotation detection control signal to the rotation detection circuit 114 in response to a voltage detection signal indicating that the battery voltage does not exceed a predetermined value so as to detect rotation with a small braking force. The rotation detection circuit 114 is controlled.
In response to the rotation detection control signal, the rotation detection circuit 114 performs the rotation detection operation at the timing shown in any of FIGS. 6 to 9, that is, in a state where the braking force is smaller than that in FIG.

  When the rotation detection operation of FIG. 6 is performed, the rotation detection circuit 114 performs the rotation detection operation after performing the operation of alternately forming the first closed circuit and the second closed circuit in the mask section IT. In other words, the transistor Q4 is driven in the ON / OFF switching state within the mask section IT, and the first time for forming the first closed circuit including the detection resistor 302 is increased within the mask section IT, whereby the stepping motor 103 Reduce the braking force. The rotation detection circuit 114 performs the rotation detection operation in the detection section DT while reducing the braking force in this way, and performs the rotation detection operation and the rotation drive operation as described above.

  When the rotation detection operation of FIG. 7 is performed, the rotation detection circuit 114 performs the rotation detection operation with the end time of the detection period T being delayed. That is, by terminating the switching operation of the transistor Q4 later than in the case of FIG. 5, the first time for forming the first closed circuit in the detection interval DT is lengthened, and the braking force of the stepping motor 103 is decreased. Thus, the rotation detection operation is performed in the detection section DT while reducing the braking force.

  When the rotation detection operation of FIG. 8 is performed, the rotation detection circuit 114 makes the first closed circuit within the detection interval DT by making the value of (first time / second time) larger than in the case of FIG. The first time for forming the is increased, and the braking force of the stepping motor 103 is decreased. Thus, the rotation detection operation is performed in the detection section DT while reducing the braking force.

  When the rotation detection operation of FIG. 9 is performed, the rotation detection circuit 114 reduces the braking force of the stepping motor 103 by making the detection cycle longer than in the case of FIG. To do. Thus, the rotation detection operation is performed in the detection section DT while reducing the braking force.

  As described above, it is possible to accurately detect the rotation by changing the braking force according to whether or not the rotation of the stepping motor 103 is easily maintained due to the influence of the voltage fluctuation of the battery 101. Moreover, since it can suppress that the side pressure of the rotating shaft of a rotor 202 and a bearing part becomes high, wear can be reduced and durability can be maintained.

In the first embodiment, when the rotation of the stepping motor 103 is difficult to maintain (for example, the battery voltage of the battery 101 does not exceed a predetermined value), the rotation detection circuit 114 applies the braking force applied to the stepping motor 103. However, when the rotation of the stepping motor 103 is easy to maintain (for example, when the battery voltage of the battery 101 exceeds a predetermined value), the rotation detection circuit 114 is used as the stepping motor. 103 may be configured to detect rotation while applying a larger braking force than when it is difficult to maintain the rotation of the stepping motor 103.
In this case, when the battery voltage detected by the voltage detection circuit 107 exceeds a predetermined value, the rotation detection control circuit 112 rotates while applying a larger braking force than when the battery voltage does not exceed the predetermined value. It can be configured to control to perform detection.

FIG. 2 is a block diagram of a stepping motor control circuit, a movement, and an analog electronic timepiece according to the second embodiment of the present invention. FIG. 2 shows an example of an analog electronic wristwatch. The same parts as those in FIG. It is attached.
In the first embodiment, the braking force is changed depending on whether or not the battery voltage of the battery 101 exceeds a predetermined value. However, in the second embodiment, the influence of the external magnetic field is further taken into consideration. The braking force is changed. That is, in the second embodiment, when the battery voltage of the battery 101 exceeds a predetermined value and the strength of the external magnetic field (either a DC magnetic field or an AC magnetic field) exceeds a predetermined value, the battery voltage of the battery 101 is And at least one of the external magnetic field strengths does not exceed the predetermined value, and the rotation detection operation is performed by increasing the braking force of the stepping motor 103. For this purpose, the second embodiment includes a magnetic field detection circuit 108 as a magnetic field detection unit, which is a component of the movement 117.

In the following, the operation of the second embodiment will be described with reference to FIGS. 2 to 9 for the parts different from the first embodiment.
In FIG. 2, the voltage detection circuit 107 detects the battery voltage of the battery 101 at a predetermined timing, and outputs a voltage detection signal representing the detected battery voltage to the control circuit 106. The magnetic field detection circuit 108 detects a magnetic field at a predetermined timing and outputs a magnetic field detection signal indicating the intensity of the detected magnetic field to the control circuit 106.

When the voltage detection signal indicates that the battery voltage exceeds the predetermined value and the magnetic field detection signal indicates that the magnetic field strength is greater than the predetermined value, the rotation detection circuit 114 causes the stepping motor 103 to operate at the timing of FIG. Rotation detection operation is performed.
That is, when both the battery voltage detected by the voltage detection circuit 107 and the magnetic field strength detected by the magnetic field detection circuit 108 exceed a predetermined value, the control circuit 106 determines that both the battery voltage and the magnetic field strength of the battery 101 exceed a predetermined value. In other words, a voltage magnetic field detection signal indicating that the rotation of the stepping motor 103 is easily maintained is output to the rotation detection control circuit 112.

The rotation detection control circuit 112 outputs a rotation detection control signal to the rotation detection circuit 114 in response to the voltage magnetic field detection signal, and controls the rotation detection circuit 114 so as to detect rotation with a large braking force.
In response to the rotation detection control signal, the rotation detection circuit 114 performs a rotation detection operation with a large braking force at the timing shown in FIG.

On the other hand, in cases other than the case where the voltage detection signal indicates that the battery voltage exceeds a predetermined value and the magnetic field detection signal indicates that the magnetic field strength is an intensity exceeding the predetermined value, the rotation detection circuit 114 is shown in FIG. The rotation detection operation of the stepping motor 103 is performed at any timing in FIG.
That is, when at least one of the battery voltage detected by the voltage detection circuit 107 and the magnetic field strength detected by the magnetic field detection circuit 108 does not exceed a predetermined value, the control circuit 106 determines that at least one of the battery voltage and the magnetic field strength of the battery 101 is predetermined. A voltage magnetic field detection signal indicating that the value does not exceed (in other words, it is difficult to maintain the rotation of the stepping motor 103) is output to the rotation detection control circuit 112.

The rotation detection control circuit 112 outputs a rotation detection control signal to the rotation detection circuit 114 in response to the voltage magnetic field detection signal, and controls the rotation detection circuit 114 so as to detect rotation with a small braking force.
In response to the rotation detection control signal, the rotation detection circuit 114 performs a rotation detection operation with a small braking force at any timing of FIGS.

Thereafter, the operation is performed in the same manner as in the first embodiment, and the stepping motor 103 is driven, the braking force is controlled, the rotation is detected, and the time hand 118 and the calendar display unit 119 are driven.
In this way, it is possible to accurately detect the rotation by changing the braking force according to whether or not the rotation of the stepping motor 103 is easily maintained by the influence of both the battery voltage and the external magnetic field. Moreover, since it can suppress that the side pressure of the rotating shaft of a rotor 202 and a bearing part becomes high, wear can be reduced and durability can be maintained.

  In the second embodiment, when the rotation of the stepping motor 103 is difficult to maintain (for example, at least one of the battery voltage and the external magnetic field strength of the battery 101 does not exceed a predetermined value), the rotation detection circuit 114 is The rotation detection is performed while applying a smaller braking force to the stepping motor 103 than when the rotation of the stepping motor 103 is easily maintained.

However, when it is easy to maintain the rotation of the stepping motor 103 (for example, when the battery voltage of the battery 101 exceeds a predetermined value and the strength of the external magnetic field exceeds a predetermined value), the rotation detection circuit 114 causes the stepping motor 103 to You may comprise so that rotation detection may be performed, applying big braking force rather than the time of the state where it is difficult to maintain the rotation of the stepping motor 103.
In this case, when both the battery voltage detected by the voltage detection circuit 107 and the magnetic field intensity detected by the magnetic field detection circuit 108 exceed a predetermined value, the rotation detection control circuit 112 causes the rotation detection circuit 114 to detect the battery voltage and the magnetic field strength. The rotation can be detected while applying a larger braking force than when at least one exceeds a predetermined value.

  As described above, the stepping motor control circuit according to the embodiment of the present invention includes the battery 101 as the power source, the voltage detection circuit 107 that detects the voltage of the battery 101, and the rotation detection that detects the rotation state of the stepping motor 103. And a control unit that drives the stepping motor 103 to rotate by selecting a drive pulse corresponding to the rotation state detected by the rotation detection unit, and the rotation detection unit is a battery 101 detected by the voltage detection circuit 107. When the voltage does not exceed the predetermined value, the rotation is detected by making the braking force of the stepping motor 103 smaller than when the voltage exceeds the predetermined value.

  Here, the rotation detection unit includes a magnetic field detection circuit 108 that detects a magnetic field, and at least one of the voltage of the battery 101 detected by the voltage detection circuit 107 and the strength of the magnetic field detected by the magnetic field detection circuit 108 is predetermined. When the value does not exceed the value, the rotation can be detected by making the braking force of the stepping motor 103 smaller than when both the voltage of the battery 101 and the strength of the magnetic field exceed the predetermined value.

  A stepping motor control circuit according to an embodiment of the present invention includes a battery 101 as a power source, a voltage detection circuit 107 that detects the voltage of the battery 101, a rotation detection unit that detects the rotation state of the stepping motor 103, and A control unit that rotates the stepping motor 103 by selecting a driving pulse according to the rotation state detected by the rotation detection unit, and the rotation detection unit has a predetermined voltage of the battery 101 detected by the voltage detection circuit 107. When the value is exceeded, the rotation is detected by increasing the braking force of the stepping motor 103 than when the value is not exceeded.

  Here, the rotation detection unit includes a magnetic field detection circuit 108 that detects a magnetic field, and the rotation detection unit exceeds the predetermined value of the voltage of the battery 101 detected by the voltage detection circuit 107 and the intensity of the magnetic field detected by the magnetic field detection circuit 108. Can be configured to detect rotation by increasing the braking force of the stepping motor 103 than when at least one of the voltage of the battery 101 and the strength of the magnetic field does not exceed the predetermined value. .

Therefore, by changing the braking force depending on whether or not the rotation of the stepping motor 103 is easily maintained, it is possible to accurately detect the rotation and maintain the durability.
Further, when the load is light, the braking force of the rotor 202 can be shifted to a low state, and only when exposed to a high power supply voltage or a strong magnetic field, the rotor 202 at the time of detecting the rotation after driving the main drive pulse P1. Since the braking force can be made high, it is possible to provide a stepping motor control circuit, a movement, and an analog electronic timepiece that can prevent the occurrence of erroneous rotation detection and the situation where the hand cannot be moved and maintain durability.
In addition, when the user wears a large needle, the braking force automatically becomes higher than when a normal needle is worn, so one kind of thing is not provided without providing a movement with different specifications. There is a merit that can be handled by.

  According to the movement 117 according to the embodiment of the present invention, it is possible to accurately detect the rotation and maintain the durability by changing the braking force according to whether or not the rotation of the stepping motor 103 is easily maintained. It is possible to construct an analog electronic timepiece that can be used.

  Further, according to the analog electronic timepiece according to the embodiment of the present invention, the rotation force can be accurately detected and changed by changing the braking force according to whether or not the rotation of the stepping motor 103 is easily maintained. Therefore, accurate hand movement is possible and the life can be extended.

A plurality of types of time for forming the first closed circuit and the second closed circuit may be prepared so that the time can be selected according to the voltage of the battery 101 and the magnetic field strength. As a result, the braking force can be changed in multiple stages.
In addition to the comb-shaped drive pulse, a rectangular-wave drive pulse may be used as the drive pulse.
Further, one type of main drive pulse P1 may be used without using a plurality of types of main drive pulses P1.

  In the present embodiment, the detection interval DT is configured by one interval. However, the detection interval DT is divided into a plurality of intervals, and the stepping motor is determined according to the pattern of the interval in which the induced signal VRs exceeding the reference threshold voltage Vcomp is detected. The rotation state (for example, the magnitude of the load with respect to the energy of the drive pulse) may be detected. In this case, as shown in FIG. 12, the braking force can be changed according to the magnitude of the load with respect to the energy of the drive pulse.

The stepping motor control circuit according to the present invention is applicable to various electronic devices that use the stepping motor.
The movement according to the present invention is applicable to movements used in various analog electronic timepieces such as analog electronic wristwatches and analog electronic table clocks.
The analog electronic timepiece according to the present invention is applicable to various analog electronic timepieces such as an analog electronic wristwatch and an analog electronic table clock.

DESCRIPTION OF SYMBOLS 101 ... Battery 102 ... Stepping motor control circuit 103 ... Stepping motor 104 ... Oscillation circuit 105 ... Dividing circuit 106 ... Control circuit 107 ... Voltage detection circuit 108 ... Magnetic field Detection circuit 109 ... main drive pulse generation circuit 110 ... correction drive pulse generation circuit 111 ... motor drive circuit 112 ... rotation detection control circuit 113 ... induced signal output time comparison circuit 114 ... rotation Detection circuit 115... Watch case 116... Analog display unit 117... Movement 118... Time hand 119... Calendar display unit 201. Through hole 204, 205 ... Notch (inner notch)
206, 207 ... Notch (outer notch)
208 ... Magnetic core 209 ... Drive coils 210, 211 ... Saturable parts 301, 302 ... Detection resistor 303 ... Switch control circuit 304 ... Comparator OUT1 ... First terminal OUT2 ...・ Second terminal

Claims (14)

A battery as a power source;
A voltage detector for detecting the voltage of the battery;
A rotation detector for detecting the rotation status of the stepping motor;
A control unit that drives and rotates the stepping motor by selecting a drive pulse corresponding to the rotation status detected by the rotation detection unit;
The rotation detection unit detects rotation by reducing the braking force of the stepping motor smaller than when the voltage of the battery detected by the voltage detection unit does not exceed a predetermined value. Motor control circuit. Having a magnetic field detector for detecting the magnetic field;
When at least one of the voltage of the battery detected by the voltage detection unit and the strength of the magnetic field detected by the magnetic field detection unit does not exceed a predetermined value, the rotation detection unit detects the voltage of the battery and the magnetic field. 2. The stepping motor control circuit according to claim 1, wherein the rotation is detected by making the braking force of the stepping motor smaller than when both of the intensities exceed the predetermined value. A battery as a power source;
A voltage detector for detecting the voltage of the battery;
A rotation detector for detecting the rotation status of the stepping motor;
A control unit that drives and rotates the stepping motor by selecting a drive pulse corresponding to the rotation status detected by the rotation detection unit;
The rotation detection unit detects rotation by increasing the braking force of the stepping motor as compared with a case where the voltage of the battery detected by the voltage detection unit exceeds a predetermined value. Motor control circuit. Having a magnetic field detector for detecting the magnetic field;
When the voltage of the battery detected by the voltage detector exceeds a predetermined value and the intensity of the magnetic field detected by the magnetic field detector exceeds a predetermined value, the rotation detector 4. The stepping motor control circuit according to claim 3, wherein the rotation is detected by increasing the braking force of the stepping motor as compared with a case where at least one of the magnetic field strengths does not exceed the predetermined value. The rotation detection unit includes a first time for forming a first closed circuit including a drive coil of the stepping motor and a detection element for detecting an induced signal generated by the stepping motor, and a second closed for short-circuiting the drive coil. In a detection period having a plurality of detection periods constituted by a second time for forming a circuit, the rotation state of the stepping motor is detected,
The braking force of the stepping motor is changed depending on whether or not the first closed circuit and the second closed circuit are alternately formed in a mask section provided immediately after the end of the drive pulse within the detection period. The stepping motor control circuit according to any one of claims 1 to 4.   The rotation detection unit performs an operation of alternately forming the first closed circuit and the second closed circuit in the mask period when detecting the rotation by reducing the braking force of the stepping motor. 5. A stepping motor control circuit according to 5. The rotation detection unit includes a first time for forming a first closed circuit including a drive coil of the stepping motor and a detection element for detecting an induced signal generated by the stepping motor, and a second closed for short-circuiting the drive coil. In a detection period having a plurality of detection periods constituted by a second time for forming a circuit, the rotation state of the stepping motor is detected,
5. The stepping motor control circuit according to claim 1, wherein a braking force of the stepping motor is changed by changing an end timing of the detection period. 6.   8. The stepping motor control circuit according to claim 7, wherein the rotation detection unit delays the end timing of the detection period when detecting rotation by reducing the braking force of the stepping motor. The rotation detection unit includes a first time for forming a first closed circuit including a drive coil of the stepping motor and a detection element for detecting an induced signal generated by the stepping motor, and a second closed for short-circuiting the drive coil. In a detection period having a plurality of detection periods constituted by a second time for forming a circuit, the rotation state of the stepping motor is detected,
5. The stepping motor control circuit according to claim 1, wherein a braking force of the stepping motor is changed by changing a ratio between the first time and the second time. 6.   The stepping motor control circuit according to claim 9, wherein the rotation detection unit increases the value of (first time / second time) when detecting rotation by reducing the braking force of the stepping motor. The rotation detection unit includes a first time for forming a first closed circuit including a drive coil of the stepping motor and a detection element for detecting an induced signal generated by the stepping motor, and a second closed for short-circuiting the drive coil. In a detection period having a plurality of detection periods constituted by a second time for forming a circuit, the rotation state of the stepping motor is detected,
The stepping motor control circuit according to claim 1, wherein the braking force of the stepping motor is changed by changing the detection cycle.   The stepping motor control circuit according to claim 11, wherein the rotation detection unit lengthens the detection cycle when detecting rotation by reducing a braking force of the stepping motor.   A movement comprising the stepping motor control circuit according to any one of claims 1 to 12.   An analog electronic timepiece comprising the movement according to claim 13.

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