Stepping motor control circuit, and analog electronic clock

Abstract

To enlarge a drive range even in a case where the number of ranks of selectable main drive pulses is limited.SOLUTION: A stepping motor control circuit comprises: a rotation detection section by which, in a detection interval in which a detection signal generated by rotations of a stepping motor is detected, a rotation situation of the stepping motor is detected according to whether or not the detection signal exceeds a predetermined reference threshold voltage in a predetermined detection interval; and a control section which performs drive control on the stepping motor using any one of a plurality of main drive pulses of mutually different energy according to a result of the detection by the rotation detection section. The control section selects the plurality of main drive pulses in such a manner that a difference of energy between the plurality of main drive pulses in a main drive pulse having a predetermined first energy or more becomes larger than a difference of energy between the plurality of main drive pulses in a main drive pulse of less than the first energy.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a stepping motor control circuit and an analog electronic watch. [Background technology]

[0002] 2. Description of the Related Art Stepping motors have conventionally been used in analog electronic watches and the like, which have a stator having a rotor accommodating hole and a positioning portion that determines the stopping position of the rotor, a rotor disposed in the rotor accommodating hole, and a coil, and which supply an alternating signal to the coil to generate magnetic flux in the stator to rotate the rotor and stop the rotor at a position corresponding to the positioning portion.

[0003] As a control circuit for controlling the stepping motor, for example, the stepping motor control circuit described in Patent Document 1 is known. After outputting a main drive pulse, the stepping motor control circuit described in Patent Document 1 judges the rotation status based on the output timing of a detection signal. By judging the rotation status, the stepping motor control circuit described in Patent Document 1 determines whether or not to output a correction drive pulse, and whether to rank down, maintain, or rank up the main drive pulse. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5363167 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the stepping motor control circuit described in Patent Document 1, due to restrictions imposed by the specifications of the control circuit, there may be a limit to the number of selectable ranks of the main drive pulse, limiting the driving range.

[0006] The present invention has been made in consideration of the above points, and provides a stepping motor control circuit and an analog electronic watch that can expand the driving range even when there is a limit to the number of selectable ranks of main driving pulses. [Means for solving the problem]

[0007] The present invention has been made to solve the above-mentioned problems, and one aspect of the present invention is a stepping motor control circuit comprising: a rotation detection unit that detects the rotation status of a stepping motor based on whether or not a detection signal generated by the rotation of a stepping motor exceeds a predetermined reference threshold voltage within a predetermined detection interval in which the detection signal is detected; and a control unit that drives and controls the stepping motor using one of a plurality of main drive pulses having different energies depending on the detection result by the rotation detection unit, wherein the control unit selects the plurality of main drive pulses such that the energy difference between a plurality of main drive pulses having a predetermined first energy or more is greater than the energy difference between a plurality of main drive pulses having main drive pulses less than the first energy.

[0008] In one aspect of the present invention, in the above-mentioned stepping motor control circuit, the first energy is the energy of a main drive pulse that continues to act even after the rotor's magnetic poles have passed the point where the stator's magnetic potential is maximum, and acts to attract the rotor toward the end of the second quadrant.

[0009] In one aspect of the present invention, in the stepping motor control circuit, the first energy is energy that results in a main drive pulse of the first energy or greater having a total length of 3.5 ms or more and 5.0 ms or less.

[0010] In one aspect of the present invention, in the stepping motor control circuit described above, when the control unit determines that the main drive pulse is an excess rotation with ample drive energy, the control unit changes the main drive pulse to a main drive pulse with less energy.

[0011] In addition, one aspect of the present invention is that in the above-mentioned stepping motor control circuit, the control unit divides the detection section which begins immediately after driving by the main drive pulse into a plurality of sections of three or more, and controls the main drive pulse according to the section in which the rotation detection unit detects a detection signal which exceeds the reference threshold voltage.

[0012] Also, one aspect of the present invention is an analog electronic watch having a stepping motor that rotates a time hand and a stepping motor control circuit that controls the stepping motor, wherein the stepping motor control circuit is a stepping motor control circuit as defined in any one of claims 1 to 5. Effect of the Invention

[0013] According to the present invention, the driving range can be expanded even when there is a limit to the number of ranks of the selectable main driving pulses. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an analog electronic timepiece using a stepping motor control circuit according to an embodiment of the present invention. [Diagram 2] 1 is a diagram illustrating an example of a configuration of a stepping motor according to an embodiment of the present invention. [Diagram 3] 5 is a timing chart for explaining an example of the operation of the stepping motor control circuit and the analog electronic timepiece according to the embodiment of the invention. [Figure 4] 5 is a timing chart showing an example of an operation of the stepping motor control circuit according to the embodiment of the present invention. FIG. [Diagram 5] 5 is a determination chart summarizing an example of an operation of a stepping motor control circuit according to an embodiment of the present invention. [Figure 6] 5 is a diagram showing an example of the relationship between the rank of a main drive pulse, a rank maintaining voltage, and a minimum drive voltage according to the embodiment of the present invention. FIG. [Figure 7]4 is a flowchart showing an example of the operation of the stepping motor control circuit and the analog electronic watch according to the embodiment of the invention. [Figure 8] FIG. 13 is a diagram illustrating an example of a second quadrant according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] (Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a diagram showing an example of the configuration of an analog electronic timepiece using a stepping motor control circuit according to this embodiment. The analog electronic timepiece is, for example, an analog electronic wristwatch.

[0016] In FIG. 1, the analog electronic timepiece includes an oscillator circuit 101, a frequency divider circuit 102, a control circuit 103, a drive pulse selection circuit 104, a stepping motor 105, an analog display unit 106, a rotation detection circuit 110, and a detection interval discrimination circuit 111.

[0017] The oscillator circuit 101 generates a signal of a predetermined frequency. A frequency divider circuit 102 divides the frequency of the signal generated by the oscillator circuit 101 to generate a clock signal that serves as a reference for timekeeping.

[0018] The control circuit 103 controls each of the electronic circuit elements that make up the electronic timepiece, and also controls changes to the drive pulses. The drive pulse selection circuit 104 selects and outputs a drive pulse for driving the motor based on a control signal from the control circuit 103. The stepping motor 105 is rotated by a drive pulse from the drive pulse selection circuit 104 .

[0019] Analog display unit 106 has time hands (three types of hands: hour hand 107, minute hand 108, and second hand 109 in the example of FIG. 1) that are rotationally driven by stepping motor 105 to display the time.

[0020] The rotation detection circuit 110 detects a detection signal (also referred to as an induced signal) VRs indicating the rotation state from the stepping motor 105 in a predetermined detection section.

[0021] The detection interval discrimination circuit 111 compares the time when the rotation detection circuit 110 detects the detection signal VRs exceeding a predetermined reference threshold voltage Vcomp with the detection interval, and determines in which interval the detection signal VRs was detected. As will be described later, in this embodiment, the detection interval for detecting the rotation state of the stepping motor 105 is divided into three intervals.

[0022] The rotation detection circuit 110 detects the detection signal VRs exceeding a predetermined reference threshold voltage Vcomp. The detection signal VRs exceeds the reference threshold voltage Vcomp when the rotor of the stepping motor 105 performs a constant fast movement. The reference threshold voltage Vcomp is set so that the detection signal VRs does not exceed the reference threshold voltage Vcomp when the rotor of the stepping motor 105 does not perform a constant fast movement. The rotor performs a constant fast movement when the stepping motor 105 rotates, etc. The rotor does not perform a constant fast movement when the stepping motor 105 does not rotate, etc. In other words, the reference threshold voltage Vcomp is a criterion for determining the voltage level of the detection signal VRs corresponding to the induced voltage generated by the free vibration of the stepping motor 105. The configuration of the rotation detection circuit 110 is similar to the configuration of the rotation detection circuit described in Patent Document 1, for example.

[0023] As described above, the rotation detection circuit 110 detects the rotation status of the stepping motor 105 based on whether or not the detection signal VRs exceeds a predetermined reference threshold voltage in one or more of the first interval T1, the second interval T2, and the third interval T3 in the detection intervals for detecting the detection signal VRs generated by the rotation of the stepping motor 105. The rotation detection circuit 110 is an example of a rotation detection unit.

[0024] Furthermore, the control circuit 103 drives and controls the stepping motor 105 with one of a plurality of main drive pulses P1 having different energies according to the detection result by the rotation detection circuit 110. The control circuit 103, the drive pulse selection circuit 104, and the detection section discrimination circuit 111 constitute an example of a control unit.

[0025] 2 is a diagram showing an example of the configuration of a stepping motor according to this embodiment, as an example, the stepping motor is a timepiece stepping motor that is generally used in analog electronic timepieces.

[0026] 2, the stepping motor 105 includes a stator 201, a rotor 202, a magnetic core 208, and a coil 209. The stator 201 has a rotor-accommodating through hole 203. The rotor 202 is rotatably disposed in the rotor-accommodating through hole 203. The magnetic core 208 is joined to the stator 201. The coil 209 is wound around the magnetic core 208.

[0027] When the stepping motor 105 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 (not shown) and joined together. The coil 209 has a first terminal OUT1 and a second terminal OUT2.

[0028] The rotor 202 is magnetized with two poles (an S pole and an N pole). At the outer end of the stator 201 made of a magnetic material, a plurality of (two in this embodiment) notches (also referred to as outer notches) 206 and a notch 207 are provided at positions facing each other across the rotor-accommodating through hole 203. A saturable portion 210 is provided between the notch 206 and the rotor-accommodating through hole 203. A saturable portion 211 is provided between the notch 207 and the rotor-accommodating through hole 203.

[0029] Saturable portion 210 and saturable portion 211 are configured so as not to be magnetically saturated by the magnetic flux of rotor 202, but to be magnetically saturated and have a large magnetic resistance when coil 209 is excited. Rotor-accommodating through-hole 203 is configured in a circular hole shape with multiple (two in this embodiment) half-moon shaped cutout portions (also referred to as inner notches) 204 and cutout portion 205 integrally formed at opposing portions of the through-hole having a circular outline.

[0030] Cutout portion 204 and cutout portion 205 each constitute a positioning portion for determining a stop position of rotor 202. When coil 209 is not excited, rotor 202 is stably stopped at a position corresponding to the positioning portion, as shown in Fig. 2. In other words, when coil 209 is not excited, rotor 202 is stably stopped at a position (angle θ0 position) where magnetic pole axis A of rotor 202 is perpendicular to the line segment connecting cutout portion 204 and cutout portion 205.

[0031] As shown in FIG. 2, the XY coordinate space centered on the rotation axis (center of rotation) of rotor 202 is divided into four quadrants (first quadrant I, second quadrant II, third quadrant III, and fourth quadrant IV).

[0032] Here, when a square wave drive pulse of one polarity is supplied from drive pulse selection circuit 104 between first terminal OUT1 and second terminal OUT2 of coil 209 (for example, the first terminal OUT1 side is positive and the second terminal OUT2 side is negative) and a current i flows in the direction indicated by arrow D1 in FIG. 2, a magnetic flux is generated in stator 201 in the direction indicated by dashed arrow D2. As a result, saturable portion 210 and saturable portion 211 are saturated and the magnetic resistance increases. Thereafter, due to the interaction between the magnetic pole generated in stator 201 and the magnetic pole of rotor 202, rotor 202 rotates 180 degrees in the direction indicated by arrow D3 in FIG. 2, and magnetic pole axis A stably stops at the position of angle θ1.

[0033] In addition, the rotation direction (counterclockwise direction in FIG. 2) for performing normal operation by rotating the stepping motor 105 is defined as the forward direction, and the opposite direction (clockwise direction) is defined as the reverse direction. In one example of this embodiment, the normal operation is the operation of moving the hands since this is an analog electronic timepiece.

[0034] Next, the drive pulse selection circuit 104 supplies a square wave drive pulse of the opposite polarity to the first terminal OUT1 and the second terminal OUT2 of the coil 209. Here, the first terminal OUT1 side is set as a negative pole and the second terminal OUT2 side is set as a positive pole so as to have a polarity opposite to that of the drive described above. When a drive pulse is supplied to the first terminal OUT1 and the second terminal OUT2 to flow a current in a direction opposite to that indicated by the arrow D1 in FIG. 2, a magnetic flux is generated in the stator 201 in a direction opposite to that indicated by the dashed arrow D2. As a result, the saturable portion 210 and the saturable portion 211 are first saturated. After that, due to the interaction between the magnetic pole generated in the stator 201 and the magnetic pole of the rotor 202, the rotor 202 rotates 180 degrees in the same direction as that indicated by the arrow D3, and the magnetic pole axis A stably stops at the position of the angle θ0.

[0035] Thereafter, by supplying signals of different polarities (alternating signals) to the coil 209, the above-mentioned operation is repeated, and the rotor 202 can be continuously rotated in the direction of the arrow by 180 degrees at a time. As will be described later, in this embodiment, a plurality of main drive pulses P10 to P1m and a correction drive pulse P2 are used as drive pulses. The plurality of main drive pulses P10 to P1m and the correction drive pulse P2 have different energies.

[0036] Figure 3 is a timing diagram for explaining an example of the operation of the stepping motor control circuit and the analog electronic clock according to the present embodiment. In FIG. 3, an example is shown when the stepping motor 105 is driven by the main drive pulse P1n of rank n and the correction drive pulse P2. In FIG. 3, the main drive pulse P1n is characterized by the rank n. The rank n is an integer having a value in the range from the minimum value 0 to the maximum value m. The main drive pulse P1n is configured such that the larger the value of the rank n, the larger the energy of the pulse. In the present embodiment, the fact that the energy of the pulse is large corresponds to the long pulse width of the rectangular wave.

[0037] The correction drive pulse P2 is a pulse having an energy large enough to drive an overload in rotation. The energy of the correction drive pulse P2 is configured to be about 10 times larger than that of the main drive pulse P1. That is, the main drive pulse P10, the main drive pulse P1n, the main drive pulse P1m, and the correction drive pulse P2 are configured such that the pulse widths are P10 < P1n < P1m < P2. Here, n is any integer from 1 to m - 1.

[0038] The reference threshold voltage Vcomp is a reference for determining the voltage level of the detection signal VRs corresponding to the induced voltage generated by the free vibration of the stepping motor 105 as described above. t is the time when the detection signal VRs exceeding the reference threshold voltage Vcomp is detected.

[0039] The first section T1 is a predetermined time immediately after the drive by the main drive pulse P1. The second section T2 is a predetermined time later than the first section T1. The third section T3 is a predetermined time later than the second section. Thus, the entire detection section T starting immediately after the drive by the main drive pulse P1 is divided into a plurality of sections. The rotation state is detected by the detection signals of the same polarity in the first section T1, the second section T2, and the third section T3.

[0040] Note that "immediately after driving by the main drive pulse P1" means immediately after it becomes practically possible to detect rotation. "Immediately after driving by the main drive pulse P1" means the time when rotation detection becomes possible after a predetermined time has elapsed within the sampling period during which sampling processing for detecting rotation is not possible after the end of driving by the main drive pulse P1, or the time when a predetermined time has elapsed during which an induced voltage generated by the end of driving of the main drive pulse P1 itself affects the detection of rotation.

[0041] Although details will be described later, in the stepping motor control circuit according to this embodiment, in the loaded state shown in Fig. 2, if the region driven by the drive pulse is designated as p1, the detection signal VRs corresponding to the induced voltage generated in region a is detected in the first section T1. The detection signal VRs generated in region c is detected in the second section T2 and the third section T3. Here, there is a larger margin of drive energy when detected in the second section T2 than in the third section T3. The detection signal VRs generated in region b is detected with opposite polarity across the first section T1 and the second section T2.

[0042] That is, since the detection signal VRs is generated by the free vibration of the rotor 202 after the drive pulse is cut off, the timing of generation of the detection signal VRs induced in the first section T1 is limited to the region from rotational drive with no spare power (almost stopped) to a region with some drive spare power, and is characterized by not being generated when there is sufficient rotational power. Region a in Fig. 2 corresponds to the region from rotational drive with no spare power to a region with some drive spare power. When there is sufficient drive power, the drive pulse is cut off in region b, and the induced voltage is output in the opposite phase. Also, due to the rotor motion, the height of the detection signal VRs in the first section T1 is inversely proportional to the decrease in drive power. By utilizing this property, it is possible to determine the degree of drive energy margin.

[0043] In this embodiment, taking into account this property, the above-mentioned detection section starting immediately after driving by the main drive pulse P1 is divided into three or more sections, and the main drive pulse P1 is controlled according to the section in which the rotation detection circuit 110 detects a detection signal VRs exceeding the reference threshold voltage Vcomp. For example, when a detection signal VRs exceeding the reference threshold voltage Vcomp occurs in the first section T1, it is determined that the rotation reserve has decreased, and the energy of the drive pulse is maintained at its current value without being changed, thereby preventing a change to a drive pulse with smaller energy.

[0044] In the stepping motor control circuit according to this embodiment, as shown in Fig. 3(a1), when a detection signal VRs exceeding the reference threshold voltage Vcomp is detected at least in the first section T1 and the second section T2, the main drive pulse P1 is not changed (no rank change). Also, as shown in Fig. 3(a2), when it is detected in all of the first section T1, the second section T2, and the third section T3, the main drive pulse P1 is not changed. As shown in Figs. 3(a1) and (a2), when the main drive pulse P1 is determined to have insufficient drive energy (insufficient rotation), the main drive pulse P1 is maintained without change.

[0045] In addition, in the stepping motor control circuit according to this embodiment, as shown in Fig. 3(b1), when a detection signal VRs exceeding the reference threshold voltage Vcomp is detected only in the first section T1 and the third section T3, the main drive pulse P1 is changed to a main drive pulse P1 with a large energy without driving with the correction drive pulse P2 (rank up). Also, as shown in Fig. 3(b2), when it is detected only in the third section, the main drive pulse P1 is changed to a main drive pulse P1 with a large energy without driving with the correction drive pulse P2 (rank up). As shown in Figs. 3(b1) and (b2), when it is determined that the main drive pulse P1 is the minimum (best) drive energy required to rotate the motor (best rotation), the main drive pulse is changed to a main drive pulse with a large energy.

[0046] In the stepping motor control circuit according to this embodiment, as shown in Fig. 3(c1), when a detection signal VRs exceeding the reference threshold voltage Vcomp is detected only in the second section T2, the main drive pulse P1 is changed to a main drive pulse P1 with lower energy (rank down). Also, as shown in Fig. 3(c2), when it is detected only in the second and third sections, the main drive pulse P1 is changed to a main drive pulse P1 with lower energy (rank down). As shown in Figs. 3(c1) and (c2), when it is determined that the main drive pulse P1 has ample drive energy (ample rotation), the main drive pulse P1 is changed to a main drive pulse with lower energy.

[0047] Therefore, when the control circuit 103 determines that the main drive pulse P1 is a margin of rotation with ample drive energy, it changes the main drive pulse P1 to a main drive pulse with smaller energy.

[0048] In the stepping motor control circuit according to this embodiment, as shown in Fig. 3(b3), if a detection signal VRs exceeding the reference threshold voltage Vcomp is not detected in any of the first section T1 to the third section T3, the main drive pulse P1 is changed to a main drive pulse P1 with a larger energy (rank up) after driving with a correction drive pulse P2. Also, as shown in Fig. 3(b4), if it is detected only in the first section T1, it is determined that there is no rotation, and after driving with a correction drive pulse P2, the main drive pulse P1 is changed to a main drive pulse P1 with a larger energy (rank up).

[0049] Fig. 4 is a timing diagram showing an example of the operation of the stepping motor control circuit according to this embodiment. Fig. 4 shows the rotation behavior of the rotor 202, the output timing of the detection signal VRs, a pattern representing the rotation state (a judgment value indicating the detection result of the detection signal VRs for each section), and a pulse control operation for each load state when the stepping motor 105 is driven by the main drive pulse P1.

[0050] 4, p1 represents an interval in which the rotor 202 of the stepping motor 105 is rotationally driven by the main drive pulse P1, and a to e represent regions representing the rotational position of the rotor 202 due to free vibration after the main drive pulse P1 is stopped. If the XY coordinate space in which the magnetic pole axis A of the rotor 202 is located as a result of its rotation is divided into a first quadrant I, a second quadrant II, a third quadrant III, and a fourth quadrant IV (see FIG. 2), the first interval T1 to the third interval T3 can be expressed as follows:

[0051] That is, in a normal load state, the first section T1 is a section for determining the initial forward rotation state of the rotor 202 in the third quadrant III of the space centered on the rotor 202, and a section for determining the initial reverse rotation state. In a normal load state, the second section T2 is a section for determining the initial reverse rotation state of the rotor 202 in the third quadrant III. In a normal load state, the third section T3 is a section for determining the rotation state after the initial reverse rotation of the rotor 202 in the third quadrant III. Here, the normal load means a load that is driven under normal circumstances. In this embodiment, the load when driving the time hand is defined as the normal load.

[0052] As described above, the reference threshold voltage Vcomp is a reference threshold voltage for determining the voltage level of the detection signal VRs generated by the stepping motor 105. The reference threshold voltage Vcomp is set so that the detection signal VRs exceeds the reference threshold voltage Vcomp when the rotor 202 performs a constant fast movement, such as when the stepping motor 105 rotates, and the detection signal VRs does not exceed the reference threshold voltage Vcomp when the rotor 202 does not perform a constant fast movement, such as when the stepping motor 105 does not rotate.

[0053] If the region driven by the drive pulse is designated as p1, the detection signal corresponding to the induced voltage generated in region a is detected in the first section T1. The detection signal VRs generated in region c is detected in either the first section T1, the second section T2, or the third section T3 depending on the load condition. Here, there is a larger margin of drive energy when it is detected in the second section T2 than in the third section T3. The detection signal VRs generated in region b is detected with the opposite polarity in the first section T1 or the second section T2 depending on the load condition.

[0054] In addition, since the detection signal VRs is generated by the free vibration of the rotor 202 after the drive pulse is cut off, the timing of generation of the detection signal VRs induced in the first section T1 is limited to a region where there is some drive margin from rotation drive with no spare power (almost stopped), and is characterized in that it is not generated when there is sufficient rotational power. In this embodiment, by taking advantage of such a characteristic, the load is judged and drive pulse control is performed based on the pattern of the detection signal VRs detected in the first section T1 to the third section T3.

[0055] 4, in the stepping motor control circuit according to this embodiment, under normal load conditions, the detection signal VRs generated in region b is detected in the first interval T1. The detection signal VRs generated in region c is detected in the first interval T1 and the second interval T2. The detection signal VRs generated after region c is detected in the third interval T3.

[0056] Here, when the rotation detection circuit 110 detects a detection signal VRs exceeding the reference threshold voltage Vcomp, the judgment value is "1", and when the rotation detection circuit 110 cannot detect a detection signal VRs exceeding the reference threshold voltage Vcomp, the judgment value is "0". In the case of normal load in Fig. 4, the detection section discrimination circuit 111 detects a pattern (0,1,0) representing the rotation status (first section judgment value, second section judgment value, third section judgment value). In the case of normal load, the control circuit 103 judges that the drive energy is excessive (excessive rotation) and performs pulse control to downgrade (pulse down) the drive energy rank of the main drive pulse P1.

[0057] Furthermore, in a state where the load has increased from the normal load state to a very small value (a state where the load increment is very small), the detection signal VRs generated in region a is detected in the first interval T1. The detection signal VRs generated in region b is detected in the first interval T1 and the second interval T2. The detection signal generated in region c is detected in the second interval T2 and the third interval T3. In the example of FIG. 4, a pattern (0,1,1) is detected as a pattern representing the rotation state. The control circuit 103 determines that there is margin of rotation, as in the case of the normal load described above, and performs pulse control to pulse down the drive energy of the main drive pulse P1.

[0058] Furthermore, in a state where the load is increasing (unsatisfactory rotation), the pattern (1, 1, 1) is detected as a pattern representing the rotation state. The control circuit 103 maintains the rank of the main drive pulse P1.

[0059] In a state where the load increment is large (borderline rotation), the pattern (1,0,1) is detected as a pattern representing the rotation state. The control circuit 103 increases the rank of the main drive pulse P1 (pulse increase).

[0060] In the non-rotating state, a pattern (0,0,0) is detected as a pattern representing the rotation state. The rotor of the stepping motor 105 does not rotate when driven only by the main drive pulse P1. The control circuit 103 drives the stepping motor 105 using the correction drive pulse P2 and increases the pulse of the main drive pulse P1.

[0061] Fig. 5 is a judgment chart summarizing an example of the operation of the stepping motor control circuit according to this embodiment. As shown in Fig. 5, when a detection signal VRs exceeding the reference threshold voltage Vcomp is detected only in the second section T2, or only in the second section T2 and the third section T3 (when the pattern representing the rotation state is pattern (0, 1, 1 / 0)), it is judged as marginal rotation with a margin of drive energy, and the main drive pulse P1 is ranked down. Note that the judgment value "1 / 0" means that the judgment value may be either "1" or "0".

[0062] When a detection signal VRs exceeding the reference threshold voltage Vcomp is detected in all of the first section T1 to the third section T3, or only the first section T1 and the second section T2 (at least the first section T1 and the second section T2) (when the pattern representing the rotation status is pattern (1, 1, 1 / 0)), it is determined that the rotation is too tight to reduce the drive energy, and the current status is maintained without changing the energy of the main drive pulse P1.

[0063] When a detection signal VRs exceeding the reference threshold voltage Vcomp is detected only in the first section T1 and the third section T3, or only in the third section T3 (when the pattern representing the rotation status is pattern (1 / 0, 0, 1)), the driving energy is determined to be the very limit of rotation, and the main driving pulse P1 is ranked up without driving with the correction driving pulse P2.

[0064] Furthermore, if a detection signal VRs exceeding the reference threshold voltage Vcomp is detected only in the first section T1, or if it is not detected in any of the first section T1 to the third section T3 (if the pattern representing the rotation status is pattern (1 / 0,0,0)), it is determined that there is no rotation, and after driving with a correction driving pulse P2, the main driving pulse P1 is ranked up.

[0065] Here, attention is paid to the rank maintaining voltage and the minimum drive voltage. The rank maintaining voltage is the voltage at which the pulse operation is maintained in Fig. 4. The minimum drive voltage is the voltage immediately before the rotor of the stepping motor 105 becomes non-rotating due to the main drive pulse P1.

[0066] FIG. 6 is a diagram showing an example of the relationship between the rank, rank maintaining voltage, and minimum drive voltage of the main drive pulse P1 according to the present embodiment.

[0067] Moreover, the higher the rank of the main drive pulse P1, the lower the rank maintaining voltage and the minimum drive voltage. However, when the rank of the main drive pulse P1 becomes high to a certain rank, the main drive pulse P1 acts even after the magnetic pole of the rotor 202 passes through the inner notch provided in the stator 201. In a state in which the main drive pulse P1 acts even after the magnetic pole of the rotor 202 passes through the inner notch, the magnetic pole of the rotor 202 is attracted to the end of the second quadrant, and the rank maintaining voltage is less likely to decrease even if the rank becomes higher. In other words, the higher the energy of the main drive pulse P1, the wider the voltage difference between the rank maintaining voltage and the minimum drive voltage tends to be. In accordance with this tendency, there is a region of the rank of the main drive pulse P1 where the main drive pulse P1 does not cause the motor to stop rotating even if the motor is down-ranked by two ranks at once. This region is also referred to as a region where the motor can be down-ranked by two ranks at once. Also, the region where the motor is not caused to stop rotating even if the motor is down-ranked by two ranks at once is also referred to as a region where the motor cannot be down-ranked by two ranks.

[0068] As described above, the inner notch provided in the stator 201 is the cutout portion 205 constituting a positioning portion for determining the stop position of the rotor 202. The position where the inner notch is provided in the stator 201 corresponds to the point where the magnetic potential of the stator 201 is maximum. The energy of the main drive pulse, which continues to act even after the magnetic pole of the rotor 202 has passed the point where the magnetic potential of the stator 201 is maximum and acts to attract the rotor 202 to the end of the second quadrant, is an example of the predetermined first energy.

[0069] As will be described below, in this embodiment, the rank of the main drive pulse P1 is selected by utilizing the above-mentioned tendency that the higher the energy of the main drive pulse P1, the wider the voltage difference between the rank maintaining voltage and the minimum drive voltage.

[0070] The number of selectable ranks of the main drive pulse P1 is predetermined and depends on the specifications of the control circuit 103. In one example of this embodiment, the number of selectable ranks of the main drive pulse P1 is four.

[0071] Area R2 shown in FIG. 6 is an example of an area where a drop in rank of two is possible. Area R2 is an area with ranks of "5", "6", "7", and "8". On the other hand, area R1 is an example of an area where a drop in rank of two is not possible. Area R1 is an area with ranks of "1", "2", "3", and "4".

[0072] In this embodiment, the control circuit 103 selects the rank of the main drive pulse P1 such that the energy difference between ranks of the main drive pulse P1 at or above a predetermined energy E1 is greater than the energy difference between ranks of the main drive pulse P1 at less than the energy E1. In this embodiment, the energy E1 is an energy that corresponds to the boundary between a region where it is possible to reduce the number of ranks by two and a region where it is not possible to reduce the number of ranks by two. In the example of FIG. 6, the energy E1 is an energy that corresponds between the rank "4" and the rank "5". The energy E1 is an example of a predetermined first energy.

[0073] In region R2 where the voltage difference between the rank maintaining voltage and the minimum drive voltage becomes wider, the rank of the main drive pulse P1 is selected by skipping one. Region R2 is specifically a region of the rank of the main drive pulse P1 where a voltage difference is expected between the rank maintaining voltage for a certain rank of the main drive pulse P1 and the minimum drive voltage that is two ranks lower than that rank. In the example of FIG. 6, selecting the rank of the main drive pulse P1 by skipping one means selecting the rank of the main drive pulse P1 from among the ranks of "2", "3", "5", and "7".

[0074] In the following description, "rank up" refers to changing to the next highest energy rank from the current rank among the selectable ranks. If the current rank is less than energy E1 and the next highest energy rank from the current rank is equal to or greater than energy E1, "rank up" refers to a rank up of two. Also, if the current rank is equal to or greater than energy E1, "rank up" refers to a rank up of two. On the other hand, if the next highest energy rank from the current rank is less than energy E1, "rank up" refers to a rank up of one.

[0075] Similarly, to rank down means to change to the next lowest energy rank from the current rank among the selectable ranks. If the current rank is a rank with energy E1 or more, to rank down means to rank down by 2 ranks. If the current rank is a rank with energy less than E1, to rank down means to rank down by 1 rank.

[0076] In the control circuit 103 according to this embodiment, the range of energy that can be supplied can be expanded compared to the conventional case, without increasing the number of ranks of the main drive pulse P1.

[0077] As described above, the control circuit 103 selects multiple main drive pulses P1 such that the difference in energy between multiple main drive pulses P1 in main drive pulses P1 having a predetermined energy E1 or more is greater than the difference in energy between multiple main drive pulses P1 in main drive pulses P1 having less energy E1.

[0078] In one example of this embodiment, the difference in energy between multiple main drive pulses P1 with less than energy E1 is the difference in energy of one rank. The difference in energy between multiple main drive pulses P1 with energy E1 or more is the difference in energy of two ranks.

[0079] Note that the energy difference between the multiple main drive pulses P1 is not limited to the above example, so long as the energy difference between the multiple main drive pulses P1 in main drive pulses P1 with energy E1 or more is greater than the energy difference between the multiple main drive pulses P1 in main drive pulses P1 with energy less than E1. For example, if the energy difference between the multiple main drive pulses P1 in main drive pulses P1 with less than energy E1 is an energy difference of one rank, the energy difference between the multiple main drive pulses P1 in main drive pulses P1 with energy E1 or more may be an energy difference of three ranks or more than three ranks.

[0080] As described above, the region where the rank can be reduced by two is determined based on the voltage difference between the rank maintenance voltage and the minimum drive voltage. The region where the rank can be reduced by two shown in FIG. 6 is an example, and is not limited thereto. Also, the range of selectable ranks shown in FIG. 6 is an example, and is not limited thereto. The region where the rank can be reduced by two and the range of selectable ranks can be changed from the example shown in FIG. 6 depending on the specifications of at least one of the stepping motor control circuit and the analog electronic watch.

[0081] 7 is a flow chart showing an example of the operation of the stepping motor control circuit and the analog electronic watch according to this embodiment. The operation of the stepping motor control circuit and the analog electronic watch is mainly the processing of the control circuit 103.

[0082] The oscillator circuit 101 generates a reference clock signal of a predetermined frequency. The frequency divider circuit 102 divides the frequency of the reference clock signal generated by the oscillator circuit 101 to generate a clock signal that serves as a reference for timekeeping. The frequency divider circuit 102 outputs the generated clock signal to the control circuit 103.

[0083] The control circuit 103 counts the time signal output by the frequency divider circuit 102 to perform a time measurement operation. The control circuit 103 first sets the rank n and the number N of the main drive pulse P1n to 0 (step S501). The control circuit 103 generates a control signal so as to drive the stepping motor 105 to rotate with the main drive pulse P10 having the minimum pulse width (step S502). The control circuit 103 outputs the generated control signal to the drive pulse selection circuit 104 (S503).

[0084] In response to a control signal from the control circuit 103, the drive pulse selection circuit 104 drives and rotates the stepping motor 105 with a main drive pulse P10. The stepping motor 105 is driven and rotated by the main drive pulse P10, and drives and rotates each of the hour hand 107, the minute hand 108, and the second hand 109. As a result, when the stepping motor 105 rotates normally, the current time is always displayed on the analog display unit 106 by the hour hand 107, the minute hand 108, and the second hand 109.

[0085] The control circuit 103 determines whether or not a detection signal VRs exceeding a reference threshold voltage Vcomp has been detected within the first interval T1 (step S504). Here, the control circuit 103 first determines whether or not a detection signal VRs exceeding a predetermined reference threshold voltage Vcomp has been detected based on the detection result of the detection signal VRs of the stepping motor 105 by the rotation detection circuit 110. When the control circuit 103 determines that the detection signal VRs has been detected, it determines whether or not the detection time t is within the first interval T1 based on the determination result of the detection interval determination circuit 111 for the detection time t at which the detection signal VRs was detected.

[0086] When the control circuit 103 determines that the detection signal VRs exceeding the reference threshold voltage Vcomp is not detected within the first interval T1 (step S504; NO), it executes the process of step S505. On the other hand, when the control circuit 103 determines that the detection signal VRs exceeding the reference threshold voltage Vcomp is detected within the first interval T1 (step S504; YES), it executes the process of step S512.

[0087] The control circuit 103 determines whether or not a detection signal VRs exceeding the reference threshold voltage Vcomp is detected within the second section T2 (step S505). The control circuit 103 performs this determination in the same manner as the determination in step S504.

[0088] When the control circuit 103 determines that the detection signal VRs exceeding the reference threshold voltage Vcomp is not detected within the second interval T2 (step S505; NO), the control circuit 103 executes the process of step S506. On the other hand, when the control circuit 103 determines that the detection signal VRs exceeding the reference threshold voltage Vcomp is detected within the second interval T2 (step S505; YES), the control circuit 103 executes the process of step S514.

[0089] The control circuit 103 determines whether or not a detection signal VRs exceeding the reference threshold voltage Vcomp is detected within the third interval T3 (step S506). The control circuit 103 performs this determination in the same manner as the determination in step S504.

[0090] When the control circuit 103 determines that the detection signal VRs exceeding the reference threshold voltage Vcomp is not detected within the third section T3 (step S506; NO), the control circuit 103 executes the process of step S507. On the other hand, when the control circuit 103 determines that the detection signal VRs exceeding the reference threshold voltage Vcomp is detected within the third section T3 (step S506; YES), the control circuit 103 executes the process of step S511.

[0091] When the control circuit 103 determines in step S506 that the detection signal VRs exceeding the reference threshold voltage Vcomp is not detected within the third section T3 (non-rotation of the pattern (0,0,0)), it drives the stepping motor 105 with the correction drive pulse P2 (step S507). After that, the control circuit 103 determines whether the rank n of the main drive pulse P1 is the maximum rank m or not (step S508).

[0092] When the control circuit 103 determines that the rank n of the main drive pulse P1 is not the maximum rank m (step S508; NO), it changes the main drive pulse P1 to a main drive pulse P1(n+q1) by increasing the rank by one (S510; FIG. 3(b3)). Here, q1 is an integer having a value of 1 or 2 according to the rank that can be selected as the next highest energy rank after rank n. The control circuit 103 drives with this main drive pulse P1(n+1) in the next drive.

[0093] On the other hand, when the control circuit 103 determines that the rank n of the main drive pulse P1 is the maximum rank m (step S508; YES), it changes the main drive pulse P1 to a main drive pulse P1(na) having a predetermined amount of energy less (step S509). The control circuit 103 drives with this main drive pulse P1(na) in the next drive. At this time, it may be changed to a main drive pulse P10 having the minimum energy in order to obtain a large power saving effect.

[0094] If the control circuit 103 determines in step S506 that a detection signal VRs exceeding the reference threshold voltage Vcomp is detected within the third section T3 (the last rotation of the pattern (0,0,1)), it determines whether the rank n of the main drive pulse P1 is the maximum rank m (step S511).

[0095] When the control circuit 103 determines that the rank n of the main drive pulse P1 is not the maximum rank m (step S511; NO), it changes the main drive pulse P1 to a main drive pulse P1(n+q1) by increasing the rank by one (S510; FIG. 3(b2)). Here, q1 is an integer having a value of 1 or 2 according to the rank that can be selected as the next highest energy rank after rank n. The control circuit 103 drives with this main drive pulse P1 in the next drive.

[0096] On the other hand, if the control circuit 103 determines in step S511 that the rank n of the main drive pulse P1 is the maximum rank m, the rank cannot be changed and so the main drive pulse P1 is not changed (step S513). The control circuit 103 drives with this main drive pulse P1 in the next drive.

[0097] When the control circuit 103 determines in step S504 that the detection signal VRs exceeding the reference threshold voltage Vcomp is detected in the first section T1, the control circuit 103 determines whether or not the detection signal VRs exceeding the reference threshold voltage Vcomp is detected in the second section T2 (step S512). The control circuit 103 performs this determination in the same manner as the determination in step S504.

[0098] When the control circuit 103 determines that the detection signal VRs exceeding the reference threshold voltage Vcomp is not detected within the second section T2 (step S512; NO), the control circuit 103 executes the process of step S506. After that, the control circuit 103 executes the above-mentioned process, thereby performing either the operation of FIG. 3(b1) or (b4). On the other hand, when the control circuit 103 determines that the detection signal VRs exceeding the reference threshold voltage Vcomp is detected in the second section T2 (step S512; YES), the control circuit 103 executes the process of step S513.

[0099] When the control circuit 103 determines in step S512 that the detection signal VRs exceeding the reference threshold voltage Vcomp is detected in the second section T2 (unsatisfactory rotation of the pattern (1,1,1 / 0)), the main drive pulse P1 is not changed (step S513). The control circuit 103 drives with this main drive pulse P1 in the next drive (FIGS. 3(a1) and (a2)).

[0100] On the other hand, if the control circuit 103 determines in step S505 that a detection signal VRs exceeding the reference threshold voltage Vcomp has been detected within the second section T2 (extra rotation of pattern (0, 1, 1 / 0)), it determines whether the rank n of the main drive pulse P1 is the lowest rank 0 (step S514).

[0101] If the control circuit 103 determines that the rank n of the main drive pulse P1 is the lowest rank 0 (step S514; YES), the rank cannot be changed, so the main drive pulse P1 is not changed (step S518). The control circuit 103 uses this main drive pulse P1 in the next drive.

[0102] On the other hand, when the control circuit 103 determines that the rank n of the main drive pulse P1 is not the lowest rank 0 (step S514; NO), it adds 1 to the number of times N (step S515). After that, the control circuit 103 determines whether the number of times N has reached a predetermined number (for example, 160) (step S516).

[0103] When the control circuit 103 determines that the number of times N has reached a predetermined number (step S516; YES), it changes the main drive pulse P1 to a main drive pulse P1(n-q2) by decreasing the rank by one, and resets the number of times N to 0 (step S517). Here, q2 is an integer having a value of 1 or 2 according to the rank that can be selected as the next lowest energy rank after rank n. Thereafter, the control circuit 103 executes the process of step S502 again (FIGS. 3(c1), (c2)). That is, when the processes from step S504 to step S505, step S514, and step S515 are performed a predetermined number of times in succession, the main drive pulse P1 is decreased by one rank.

[0104] On the other hand, when the control circuit 103 determines that the number of times N has not reached the predetermined number (step S516; NO), the rank is not changed (step S518). This completes the explanation of the operation of the stepping motor control circuit and the analog electronic watch.

[0105] In the present embodiment, an example in which the predetermined first energy is the energy E1 has been described, but the present invention is not limited to this. The predetermined first energy may be the energy of a main drive pulse that continues to act even after the magnetic pole of the rotor 202 passes the point where the magnetic potential of the stator is maximum, and acts to attract the rotor 202 to the end of the second quadrant II. As described above, the second quadrant II is a quadrant (area) in which X takes a negative value and Y takes a positive value when the XY coordinate space centered on the rotation axis of the rotor 202 is divided into four quadrants. FIG. 8 shows the second quadrant II. In FIG. 8, the rotation behavior of the rotor 202 is an example.

[0106] The energy of the main drive pulse, which continues to act even after the magnetic poles of the rotor 202 pass the point where the magnetic potential of the stator is maximum and acts to attract the rotor 202 to the end of the second quadrant II, corresponds one-to-one to the energy of the rank included in the above-mentioned area where two ranks can be reduced. Therefore, the main drive pulse P1, which has the energy of the main drive pulse, which continues to act even after the magnetic poles of the rotor 202 pass the point where the magnetic potential of the stator is maximum and acts to attract the rotor 202 to the end of the second quadrant II, is capable of reducing the rank by two.

[0107] As another example, the predetermined first energy may be an energy that results in a main drive pulse P1 having a total length of 3.5 ms or more and 5.0 ms or less of the first energy or more. In other words, the control circuit 103 may select multiple main drive pulses P1 such that the difference in energy between multiple main drive pulses P1 in main drive pulses P1 having a total length of 3.5 ms or more and 5.0 ms or less is greater than the difference in energy between multiple main drive pulses P1 in main drive pulses P1 having a total length of less than 3.5 ms.

[0108] The main drive pulse P1 having a total length of 3.5 ms or more and 5.0 ms or less can continue to act even after the magnetic pole of the rotor 202 passes the point where the magnetic potential of the stator is maximum, and can act to attract the rotor 202 to the end of the second quadrant II. Therefore, with the main drive pulse P1 having a total length of 3.5 ms or more and 5.0 ms or less, the control circuit 103 can perform two rank down.

[0109] On the other hand, a main drive pulse P1 whose total length exceeds 5.0 ms holds the magnetic poles of the rotor 202 at the end of the second quadrant II, making it difficult to generate a rotation detection signal Vrs. Therefore, when a main drive pulse P1 whose total length exceeds 5.0 ms is used, it is considered that it becomes difficult to detect the rotation state of the stepping motor 105 based on the rotation detection signal Vrs.

[0110] In this embodiment, an example of a case where the rank is lowered when the rotation is performed a predetermined number of times (N times) in succession has been described, but the present invention is not limited to this. When a detection signal VRs exceeding the reference threshold voltage Vcomp is detected once within the second section T2 in step S505 of the process shown in Fig. 7, if the main drive pulse P1 at that time is not the lowest rank 0, the rank may be lowered by one. With this configuration, since it is not necessary to set the number of times N, it is sufficient to initially set the rank n to the lowest rank 0 in step S501 without initializing the number of times. Since it is not necessary to count the number of times N, the configuration is simpler than in this embodiment.

[0111] In the present embodiment, an example has been described in which, when the main drive pulse P1 has the maximum energy, the main drive pulse P1 is changed to a main drive pulse P1 having a smaller energy, but the present invention is not limited to this. After driving with the correction drive pulse P2, when the main drive pulse P1 driven in step S508 of the process shown in FIG. 7 has the maximum energy, step S518 may be executed so as not to change the main drive pulse P1.

[0112] According to this configuration, when the motor load is restored to a normal state by driving with the correction driving pulse P2, and the motor can be rotated again by the main driving pulse P1, the next drive is performed by the main driving pulse P1m with maximum energy. This makes it possible to more reliably rotate by the main driving pulse P1. Therefore, when the motor load is restored to a normal state, it is more likely that the motor can be avoided from being driven by the correction driving pulse P2, making it possible to save energy.

[0113] In addition, in the present embodiment, an example in which the detection section is divided into three sections (first section T1, second section T2, and third section T3) has been described, but the present invention is not limited to this. The detection section may be divided into four sections, or five or more sections. Therefore, the control circuit 103 divides the detection section that starts immediately after driving by the main drive pulse P1 into a plurality of sections, three or more sections, and controls the main drive pulse P1 according to the section in which the rotation detection circuit 110 detects a detection signal that exceeds the reference threshold voltage Vcomp. By dividing the detection section into four or more sections, the rotation status of the stepping motor can be detected more accurately than when the detection section is divided into three sections.

[0114] As described above, the stepping motor control circuit of this embodiment includes a rotation detection unit (in this embodiment, the rotation detection circuit 110) and a control unit (in this embodiment, the control circuit 103, the drive pulse selection circuit 104, and the detection section discrimination circuit 111). The rotation detection unit (in this embodiment, the rotation detection circuit 110) detects the rotation status of the stepping motor 105 based on whether or not the detection signal VRs generated by the rotation of the stepping motor 105 exceeds a predetermined reference threshold voltage within a predetermined detection interval (in this embodiment, one or more of the first interval T1, the second interval T2, and the third interval T3). The control unit (in this embodiment, the control circuit 103, the drive pulse selection circuit 104, and the detection section discrimination circuit 111) drives and controls the stepping motor 105 using one of a plurality of main drive pulses P1 having different energies depending on the detection result by the rotation detection unit (in this embodiment, the rotation detection circuit 110). The control unit (in this embodiment, the control circuit 103, the drive pulse selection circuit 104, and the detection section discrimination circuit 111) selects multiple main drive pulses P1 so that the energy difference between multiple main drive pulses P1 (in this embodiment, main drive pulses ranked "5" and "7") in main drive pulses P1 that have a predetermined first energy (in this embodiment, energy E1) or more is greater than the energy difference between multiple main drive pulses P1 (in this embodiment, main drive pulses ranked "2" and "3") in main drive pulses P1 that have less than the first energy (in this embodiment, energy E1).

[0115] With this configuration, in the stepping motor control circuit of this embodiment, the range of energy that can be supplied can be expanded compared to the conventional case without increasing the number of ranks of the main drive pulse P1, so that the drive range can be expanded even when there is a limit to the number of selectable ranks of the main drive pulse.

[0116] In this embodiment, the pulse width is made different in order to change the energy of each main drive pulse P1, but the drive energy can also be changed by changing the pulse voltage, etc. Also, the main drive pulse P1 may be configured to have a comb-tooth chopping waveform, and the drive energy of the main drive pulse P1 may be changed by changing the number of choppings or the duty ratio.

[0117] Furthermore, the stepping motor control circuit according to this embodiment can be applied to stepping motors for driving not only the hour hands but also the calendars of various analog electronic timepieces with calendar functions. Although an electronic watch has been used as an example of an application of a stepping motor, the present invention can be applied to any electronic device that uses a motor.

[0118] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design changes, etc. are possible within the scope that does not deviate from the gist of the present invention. [Explanation of symbols]

[0119] 101... Oscillator circuit 102...Frequency divider circuit 103 Control circuit 104 Drive pulse selection circuit 105···Stepping motor 106 Analog display 107...Hour hand 108...Minute hand 109...Second hand 110 Rotation detection circuit 111: Detection section discrimination circuit 201 Stator 202 Rotor 203 Rotor accommodation hole 204, 205....Notch (inner notch) 206, 207... Cutout portion (outer notch) 208...magnetic core 209... Coil 210, 211...Saturable part OUT1...1st terminal OUT2: Second terminal

Claims

1. a rotation detector that detects the rotation status of the stepping motor based on whether or not a detection signal generated by the rotation of the stepping motor exceeds a predetermined reference threshold voltage within a predetermined detection section; a control unit that drives and controls the stepping motor using any one of a plurality of main drive pulses having different energies according to a detection result by the rotation detection unit; Equipped with The control unit selects the plurality of main drive pulses such that a difference in energy between the plurality of main drive pulses having a predetermined first energy or more is greater than a difference in energy between the plurality of main drive pulses having a main drive pulse less than the first energy. Stepping motor control circuit.

2. The first energy is the energy of the main drive pulse that continues to act after the rotor pole passes the point where the magnetic potential of the stator is maximum, and acts to attract the rotor to the end of the second quadrant.

2. The stepping motor control circuit according to claim 1.

3. The first energy is an energy that causes a main drive pulse having a total length of 3.5 ms or more and 5.0 ms or less, the main drive pulse having the first energy or more being equal to or more than the first energy.

2. The stepping motor control circuit according to claim 1.

4. When the control unit determines that the main drive pulse is a margin rotation with a margin of drive energy, the control unit changes the main drive pulse to a main drive pulse with a small energy.

2. The stepping motor control circuit according to claim 1.

5. The control unit divides the detection section, which starts immediately after driving by the main drive pulse, into a plurality of sections, which are equal to or greater than three sections, and controls the main drive pulse according to the section in which the rotation detection unit detects a detection signal exceeding the reference threshold voltage.

2. The stepping motor control circuit according to claim 1.

6. An analog electronic timepiece having a stepping motor that rotates a time hand and a stepping motor control circuit that controls the stepping motor, The stepping motor control circuit is a stepping motor control circuit according to any one of claims 1 to 5. Analog electronic clock.

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