Stepping motor control circuit and analog electronic timepiece

Abstract

The invention relates to a stepping motor control circuit and an analog electronic timepiece. The drive range can be expanded even if there is a limit in the number of selectable main drive pulse levels. The stepping motor control circuit includes: a rotation detection unit that detects a rotation state of the stepping motor in a detection interval in which a detection signal generated by rotation of the stepping motor is detected on the basis of whether or not the detection signal exceeds a predetermined reference threshold voltage within a predetermined detection interval; and a control unit that drives and controls the stepping motor by any one of a plurality of main drive pulses having different energies on the basis of the detection result of the rotation detection unit. The control unit selects the plurality of main drive pulses such that the difference in energy between the plurality of main drive pulses among the main drive pulses having a predetermined first energy or more is greater than the difference in energy between the plurality of main drive pulses among the main drive pulses having a smaller energy than the first energy.

Description

Technical Field

[0001] The invention relates to a stepping motor control circuit and an analog electronic clock. Background Art

[0002] In the past, stepper motors were used in analog electronic clocks and the like. The stepper motors had: a stator having a rotor receiving hole and a positioning portion for determining a stop position of the rotor; a rotor disposed in the rotor receiving hole; and a coil. The stepper motor supplies an alternating signal to the coil to generate a magnetic flux in the stator, thereby rotating the rotor and stopping the rotor at a position corresponding to the positioning portion.

[0003] For example, as a control circuit for controlling the above-mentioned stepping motor, there is known a stepping motor control circuit described in Patent Document 1. The stepping motor control circuit described in Patent Document 1 determines the rotation condition based on the output timing of the detection signal after outputting the main drive pulse. The stepping motor control circuit described in Patent Document 1 determines the output of the correction drive pulse and whether to reduce the level, maintain the level, or increase the level of the main drive pulse by determining the rotation condition.

[0004] Patent Document 1: Japanese Patent No. 5363167

[0005] However, in the stepping motor control circuit described in Patent Document 1, the number of selectable main drive pulse levels is sometimes limited due to restrictions on the specifications of the control circuit, and the drive range is sometimes restricted. Summary of the invention

[0006] The present invention is accomplished in view of the above situation and provides a stepping motor control circuit and an analog electronic clock, which can expand the driving range even when the number of levels of selectable main driving pulses is limited.

[0007] The present invention is completed to solve the above-mentioned problems. One embodiment of the present invention is a stepper motor control circuit, wherein the stepper motor control circuit has: a rotation detection unit, which detects the rotation condition of the stepper motor in a detection interval of a detection signal generated by the rotation of the stepper motor according to whether the detection signal exceeds a specified reference threshold voltage within a specified detection interval; and a control unit, which drives and controls the stepper motor through any one of a plurality of main drive pulses with different energies based on the detection result of the rotation detection unit, and the control unit selects the plurality of main drive pulses in a manner such that the energy difference between the plurality of main drive pulses among the main drive pulses having a first energy or higher is greater than the energy difference between the plurality of main drive pulses among the main drive pulses having a first energy or lower.

[0008] In addition, in one embodiment of the present invention, in the above-mentioned stepping motor control circuit, the first energy refers to the energy of the main drive pulse which continues to act even after the magnetic pole of the rotor passes the point where the magnetic potential of the stator is maximum and acts in a manner that attracts the rotor to the end of the second quadrant.

[0009] According to one aspect of the present invention, in the stepping motor control circuit, the first energy is an energy of a main drive pulse having a total length of 3.5 ms to 5.0 ms, which is equal to or greater than the first energy.

[0010] According to one aspect of the present invention, in the stepping motor control circuit, when the control unit determines that the main drive pulse is a surplus rotation with surplus drive energy, the control unit changes the main drive pulse to a main drive pulse with less energy.

[0011] In addition, in one embodiment of the present invention, in the above-mentioned stepper motor control circuit, the control unit divides the detection interval starting immediately after driving with the main drive pulse into a plurality of intervals of more than 3 intervals, and controls the main drive pulse according to the interval in which the rotation detection unit detects a detection signal exceeding the reference threshold voltage.

[0012] In addition, one embodiment of the present invention is an analog electronic clock, which has: a stepping motor that rotates and drives the time hand; and a stepping motor control circuit that controls the stepping motor, wherein the stepping motor control circuit is the stepping motor control circuit described in any one of aspects 1 to 5.

[0013] According to the present invention, even when there is a limit to the number of selectable levels of the main drive pulse, the driving range can be expanded. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a diagram showing an example of the structure of an analog electronic timepiece using the stepping motor control circuit according to the embodiment of the present invention.

[0015] Figure 2 This is a diagram showing an example of the structure of a stepping motor according to an embodiment of the present invention.

[0016] Figure 3 This 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 present invention.

[0017] Figure 4 This is a timing chart showing an example of the operation of the stepping motor control circuit according to the embodiment of the present invention.

[0018] Figure 5This is a determination chart summarizing an example of the operation of the stepping motor control circuit according to the embodiment of the present invention.

[0019] Figure 6 This is a diagram showing an example of the relationship among the level of the main driving pulse, the level maintaining voltage, and the minimum driving voltage according to the embodiment of the present invention.

[0020] Figure 7 This is a flowchart showing an example of the operation of the stepping motor control circuit and the analog electronic timepiece according to the embodiment of the present invention.

[0021] Figure 8 This is a diagram showing an example of the second quadrant according to the embodiment of the present invention.

[0022] Description of symbols

[0023] 101: oscillation circuit; 102: frequency division circuit; 103: control circuit; 104: drive pulse selection circuit; 105: stepping motor; 106: analog display unit; 107: hour hand; 108: minute hand; 109: second hand; 110: rotation detection circuit; 111: detection interval discrimination circuit; 201: stator; 202: rotor; 203: through hole for accommodating the rotor; 204, 205: cutout portion (inner notch); 206, 207: cutout portion (outer notch); 208: magnetic core; 209: coil; 210, 211: saturable portion; OUT1: first terminal; OUT2: second terminal. DETAILED DESCRIPTION

[0024] (Implementation Method)

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 1 is a diagram showing an example of the structure of an analog electronic timepiece using the stepping motor control circuit of the present embodiment. As an example, the analog electronic timepiece is an analog electronic wristwatch.

[0026] exist Figure 1 In the embodiment, the analog electronic timepiece includes an oscillation circuit 101 , a frequency division 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 section determination circuit 111 .

[0027] The oscillation circuit 101 generates a signal of a predetermined frequency.

[0028] The frequency dividing circuit 102 divides the frequency of the signal generated by the oscillation circuit 101 to generate a clock signal serving as a timing reference.

[0029] The control circuit 103 performs control such as control of each electronic circuit element constituting the electronic timepiece and control of changing a drive pulse.

[0030] The drive pulse selection circuit 104 selects and outputs a drive pulse for rotationally driving the motor based on a control signal from the control circuit 103 .

[0031] The stepping motor 105 is rotationally driven by the drive pulse from the drive pulse selection circuit 104 .

[0032] The analog display unit 106 has a time hand (in Figure 1 In the example, there are three types of hour hand 107, minute hand 108, and second hand 109).

[0033] The rotation detection circuit 110 detects a detection signal (also referred to as an induction signal) VRs indicating the rotation status from the stepping motor 105 in a predetermined detection interval.

[0034] The detection interval determination circuit 111 compares the time when the detection signal VRs exceeding the predetermined reference threshold voltage Vcomp is detected by the rotation detection circuit 110 with the detected interval, and determines in which interval the detection signal VRs is detected. In addition, as described later, in this embodiment, the detection interval for detecting the rotation status of the stepping motor 105 is divided into three intervals.

[0035] The rotation detection circuit 110 detects a detection signal VRs that exceeds a predetermined reference threshold voltage Vcomp. When the rotor of the stepping motor 105 performs a constant rapid motion, the detection signal VRs exceeds the reference threshold voltage Vcomp. 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 rapid motion. The constant rapid motion of the rotor refers to the case where the stepping motor 105 rotates, etc. The case where the rotor does not perform a constant rapid motion refers to the case where the stepping motor 105 does not rotate, etc. In other words, 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.

[0036] The configuration of the rotation detection circuit 110 is the same as that of the rotation detection circuit described in Patent Document 1, for example.

[0037] As described above, the rotation detection circuit 110 detects the rotation status of the stepping motor 105 based on whether 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 interval 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.

[0038] Furthermore, the control circuit 103 drives and controls the stepping motor 105 using any one of a plurality of main drive pulses P1 having different energies according to the detection result of the rotation detection circuit 110. The control circuit 103, the drive pulse selection circuit 104 and the detection section determination circuit 111 constitute an example of a control unit.

[0039] Figure 2 1 is a diagram showing an example of the structure of the stepping motor of the present embodiment. As an example, this stepping motor is a timepiece stepping motor generally used in analog electronic timepieces.

[0040] exist Figure 2 In the embodiment, the stepping motor 105 includes a stator 201, a rotor 202, a core 208, and a coil 209. The stator 201 includes a rotor housing through hole 203. The rotor 202 is rotatably disposed in the rotor housing through hole 203. The core 208 is joined to the stator 201. The coil 209 is wound around the core 208.

[0041] When the stepping motor 105 is used in an analog electronic timepiece, the stator 201 and the core 208 are fixed to a base plate (not shown) by screws (not shown) and joined to each other. The coil 209 has a first terminal OUT1 and a second terminal OUT2.

[0042] The rotor 202 is magnetized into two poles (S pole and N pole). A plurality of (two in this embodiment) cutouts (also referred to as outer notches) 206 and a cutout 207 are provided at the outer end of the stator 201 formed of a magnetic material at positions opposite to each other across the rotor housing through hole 203. A saturable portion 210 is provided between the cutout 206 and the rotor housing through hole 203. A saturable portion 211 is provided between the cutout 207 and the rotor housing through hole 203.

[0043] The saturable portion 210 and the saturable portion 211 are each configured so as not to be magnetically saturated by the magnetic flux of the rotor 202, but to be magnetically saturated when the coil 209 is excited, thereby increasing the magnetic resistance. The rotor housing through hole 203 is configured so as to be a circular hole having a plurality of (two in this embodiment) half-moon-shaped cutouts (also referred to as inner notches) 204 and a cutout 205 integrally formed at opposing portions of a through hole having a circular outline.

[0044] The cutouts 204 and 205 respectively constitute positioning portions for determining the stop position of the rotor 202. When the coil 209 is not excited, Figure 2 In other words, when the coil 209 is not excited, the rotor 202 stably stops at a position where the magnetic pole axis A of the rotor 202 is perpendicular to the line segment connecting the cutout 204 and the cutout 205 (the position of angle θ0).

[0045] like Figure 2 As shown, the XY coordinate space centered on the rotation axis (rotation center) of the rotor 202 is divided into four quadrants (a first quadrant I, a second quadrant II, a third quadrant III, and a fourth quadrant IV).

[0046] Here, when a rectangular wave driving pulse of one polarity is supplied from the driving pulse selection circuit 104 to between the first terminal OUT1 and the second terminal OUT2 of the coil 209 (for example, the first terminal OUT1 side is set as the positive pole and the second terminal OUT2 side is set as the negative pole), the current i is set to Figure 2 When the magnetic flux flows in the direction indicated by the arrow D1, a magnetic flux is generated in the stator 201 in the direction indicated by the dotted arrow D2. As a result, the saturable portion 210 and the saturable portion 211 are saturated and the magnetic resistance increases. Then, due to the interaction between the magnetic poles generated in the stator 201 and the magnetic poles of the rotor 202, the rotor 202 moves in the direction indicated by the dotted arrow D2. Figure 2 The magnetic pole axis A rotates 180 degrees in the direction indicated by the arrow D3, and stops stably at the position of the angle θ1.

[0047] In addition, the rotation direction (in Figure 2 In one example of the present embodiment, since it is an analog electronic clock, the normal action is the needle movement.

[0048] Next, a rectangular wave driving pulse of opposite polarity is supplied from the driving pulse selection circuit 104 to the first terminal OUT1 and the second terminal OUT2 of the coil 209. Here, in order to achieve the opposite polarity to the above driving, the first terminal OUT1 side is set to the negative pole and the second terminal OUT2 side is set to the positive pole. When the driving pulse is supplied to the first terminal OUT1 and the second terminal OUT2, the current is made to be in the same direction as that of the first terminal OUT1 and the second terminal OUT2. Figure 2 When the magnetic flux flows in the direction opposite to the direction indicated by the arrow D1, a magnetic flux is generated in the stator 201 in the direction opposite to the direction indicated by the dotted arrow D2. As a result, the saturable portion 210 and the saturable portion 211 are first saturated. Then, by the interaction between the magnetic poles generated in the stator 201 and the magnetic poles of the rotor 202, the rotor 202 rotates 180 degrees in the same direction as the direction indicated by the arrow D3, and the magnetic pole axis A stably stops at the position of the angle θ0.

[0049] Thereafter, it is configured such that by supplying signals (alternating signals) with different polarities to the coil 209, the above-described operation can be repeated, and the rotor 202 can be continuously rotated 180 degrees each time in the arrow direction. Further, as will be described later, in the present embodiment, a plurality of main drive pulses P10 to P1m and a correction drive pulse P2 are used as drive pulses. The energies of the plurality of main drive pulses P10 to P1m and the correction drive pulse P2 are different from each other.

[0050] Figure 3 is a timing chart showing an example of the operation of the stepping motor control circuit and the analog electronic clock according to the present embodiment. In Figure 3 an example is shown in the case where the stepping motor 105 is driven by the main drive pulse P1n of level n and the correction drive pulse P2. In Figure 3 the main drive pulse P1n is characterized by level n. The level 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 level n, the greater the energy of the pulse. In the present embodiment, a large energy of the pulse corresponds to a long pulse width of the rectangular wave.

[0051] The correction drive pulse P2 is a pulse having a large energy sufficient to drive and rotate an excessive load. 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 in the range of 1 to m - 1.

[0052] As described above, 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. t is the time when the detection signal VRs exceeding the reference threshold voltage Vcomp is detected.

[0053] The first interval T1 is a predetermined time immediately after driving by the main drive pulse P1. The second interval T2 is a predetermined time later than the first interval T1. The third interval T3 is a predetermined time later than the second interval. In this way, the entire detection interval T starting immediately after driving by the main drive pulse P1 is divided into a plurality of intervals. For the rotation state, it is detected by the detection signals of the same polarity in the first interval T1, the second interval T2, and the third interval T3.

[0054] In addition, "immediately after driving with the main drive pulse P1" means immediately at the moment when rotation detection can actually be performed, and "immediately after driving with the main drive pulse P1" means the moment when rotation detection can be performed after a specified time within the sampling cycle when sampling processing for rotation detection cannot be performed after the driving with the main drive pulse P1 is completed, or the moment after a specified time when the induced voltage generated by the completion of driving with the main drive pulse P1 itself affects the rotation detection.

[0055] The details are described later. In the stepping motor control circuit of this embodiment, Figure 2 In the load state shown, when the area driven by the driving pulse is set to p1, the detection signal VRs corresponding to the induced voltage generated in the area a is detected in the first interval T1. The detection signal VRs generated in the area c is detected in the second interval T2 and the third interval T3. Here, the remaining amount (surplus amount) of the driving energy detected in the second interval T2 is larger than that in the third interval T3. The detection signal VRs generated in the area b is detected with opposite polarity across the first interval T1 and the second interval T2.

[0056] That is, the detection signal VRs is generated by the free vibration of the rotor 202 after the drive pulse is disconnected, and therefore has the following characteristics: the generation timing of the detection signal VRs induced in the first interval T1 is limited to the area from the rotation drive with no spare force (almost stopped) to the area with a certain degree of drive margin, and will not be generated when there is sufficient rotational force. Figure 2 The region a corresponds to a region from the rotational drive without spare power to a region with a certain degree of drive margin.

[0057] When the remaining driving force is sufficient, the driving pulse is turned off in region b, and thus the induced voltage is output in the opposite phase. In addition, due to the movement of the rotor, the height of the detection signal VRs in the first interval T1 is inversely proportional to the decrease in the remaining driving force. This property can be used to determine the degree of remaining driving pulse energy.

[0058] In the present embodiment, by utilizing this property, the detection interval starting immediately after driving with the main drive pulse P1 is divided into a plurality of intervals of three or more intervals, and the main drive pulse P1 is controlled according to the interval in which the detection signal VRs exceeding the reference threshold voltage Vcomp is detected by the rotation detection circuit 110. For example, when the detection signal VRs exceeding the reference threshold voltage Vcomp is generated in the first interval T1, it is determined that the remaining rotation force is reduced, and the current value of the energy of the drive pulse is maintained without being changed, thereby not changing to a drive pulse with a smaller energy.

[0059] In the stepping motor control circuit of this embodiment, Figure 3 As shown in (a1), when the detection signal VRs exceeding the reference threshold voltage Vcomp is detected in at least the first interval T1 and the second interval T2, the main drive pulse P1 is not changed (the level is not changed). Figure 3 As shown in (a2) of FIG. 1 , even when the main drive pulse P1 is detected in all of the first interval T1, the second interval T2, and the third interval T3, the main drive pulse P1 is not changed. Figure 3 As shown in (a1) and (a2), when it is determined that the main drive pulse P1 has a non-residual drive energy (non-residual rotation), the main drive pulse P1 is maintained without being changed.

[0060] In addition, in the stepping motor control circuit of this embodiment, if Figure 3 As shown in (b1), when the detection signal VRs exceeding the reference threshold voltage Vcomp is detected only in the first interval T1 and the third interval T3, the main drive pulse P1 is changed to a main drive pulse P1 with large energy (level increase) without driving based on the correction drive pulse P2. Figure 3 As shown in (b2), when it is detected only in the third interval, the main drive pulse P1 is changed to a main drive pulse P1 with high energy (level increase) without driving based on the correction drive pulse P2. Figure 3 As shown in (b1) and (b2), when it is determined that the main drive pulse P1 has the minimum (critical) drive energy (critical rotation) required for the rotation of the motor, the main drive pulse is changed to a main drive pulse with greater energy.

[0061] In addition, in the stepping motor control circuit of this embodiment, if Figure 3 As shown in (c1), when the detection signal VRs exceeding the reference threshold voltage Vcomp is detected only in the second interval T2, the main drive pulse P1 is changed to a main drive pulse P1 with low energy (the level is reduced). Figure 3 As shown in (c2), even when the main drive pulse P1 is detected only in the second and third intervals, the main drive pulse P1 is changed to a main drive pulse P1 with low energy (the level is reduced). Figure 3 As shown in (c1) and (c2), when it is determined that the main drive pulse P1 has a surplus drive energy (surplus rotation), the main drive pulse P1 is changed to a main drive pulse with a smaller energy.

[0062] Therefore, when determining that the main drive pulse P1 is a surplus rotation with surplus drive energy, the control circuit 103 changes the main drive pulse P1 to a main drive pulse with less energy.

[0063] In addition, in the stepping motor control circuit of this embodiment, if Figure 3 As shown in (b3), when the detection signal VRs exceeding the reference threshold voltage Vcomp is not detected in any of the first interval T1 to the third interval T3, after driving based on the correction drive pulse P2, the main drive pulse P1 is changed to a main drive pulse P1 with high energy (level increase). Figure 3 As shown in (b4), when it is detected only in the first section T1, it is determined that there is no rotation and after driving based on the correction drive pulse P2, the main drive pulse P1 is changed to a main drive pulse P1 with large energy (level increase).

[0064] Figure 4 1 is a timing chart showing an example of the operation of the stepping motor control circuit according to the present embodiment. Figure 4 The state of the load when the stepping motor 105 is driven by the main drive pulse P1 shows the rotation behavior of the rotor 202, the output timing of the detection signal VRs, the pattern representing the rotation condition (the judgment value representing the detection result of the detection signal VRs in each interval) and the pulse control action.

[0065] exist Figure 4 In FIG. 1 , p1 indicates a section in which the rotor 202 of the stepping motor 105 is driven to rotate by the main drive pulse P1. In addition, a to e are regions indicating the rotation position of the rotor 202 due to free vibration after the driving by the main drive pulse P1 is stopped.

[0066] When the XY coordinate space in which the magnetic pole axis A of the rotor 202 is located as the rotor 202 rotates is divided into the first quadrant I, the second quadrant II, the third quadrant III, and the fourth quadrant IV (refer to Figure 2 ), the first interval T1 to the third interval T3 can be expressed as follows.

[0067] That is, under the 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 the section for determining the initial reverse rotation state, and under the 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. Under the normal load state, the third section T3 is a section for determining the initial reverse rotation state of the rotor 202 in the third quadrant III. Here, the normal load refers to a load driven in normal times. In this embodiment, the load when the time pointer is driven is set to the normal load.

[0068] 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 such that when the stepping motor 105 rotates, the rotor 202 performs a constant rapid motion, the detection signal VRs exceeds the reference threshold voltage Vcomp, and when the stepping motor 105 does not rotate, the rotor 202 does not perform a constant rapid motion, the detection signal VRs does not exceed the reference threshold voltage Vcomp.

[0069] When the area driven by the driving pulse is set to p1, the detection signal corresponding to the induced voltage generated in the area a is detected in the first interval T1. Depending on the load state, the detection signal VRs generated in the area c is detected in any one of the first interval T1, the second interval T2, and the third interval T3. Here, the margin of the driving energy detected in the second interval T2 is larger than that in the third interval T3. Depending on the load state, the detection signal VRs generated in the area b is detected with opposite polarity in the first interval T1 or the second interval T2.

[0070] In addition, the detection signal VRs is generated by the free vibration of the rotor 202 after the drive pulse is disconnected, and therefore has the following characteristics: the generation timing of the detection signal VRs induced in the first interval T1 is limited to the area from the rotation drive with no spare force (almost stopped) to the area with a certain degree of drive margin, and will not be generated when there is sufficient rotation force. In this embodiment, using this characteristic, the load is determined based on the pattern of the detection signal VRs detected in the first interval T1 to the third interval T3, and the drive pulse control is performed.

[0071] For example, in Figure 4 In the stepping motor control circuit of this embodiment, under normal load conditions, the detection signal VRs generated in the region b is detected in the first interval T1. The detection signal VRs generated in the region c is detected in the first interval T1 and the second interval T2. The detection signal VRs generated after the region c is detected in the third interval T3.

[0072] Here, the case where the rotation detection circuit 110 detects the detection signal VRs exceeding the reference threshold voltage Vcomp is set to a determination value of "1", and the case where the rotation detection circuit 110 does not detect the detection signal VRs exceeding the reference threshold voltage Vcomp is set to a determination value of "0". Figure 4In the case of a normal load, the detection interval determination circuit 111 detects a pattern (0, 1, 0) as a pattern indicating the rotation condition (determination value of the first interval, determination value of the second interval, determination value of the third interval). In the case of a normal load, the control circuit 103 determines that the drive energy is too large (marginal rotation), and performs pulse control in a manner of reducing the drive energy level of the main drive pulse P1 (pulse down).

[0073] In addition, in a state where a very small load is added from a normal load state (a state where a load increment is very small), a detection signal VRs generated in region a is detected in the first interval T1. A detection signal VRs generated in region b is detected in the first interval T1 and the second interval T2. A detection signal generated in region c is detected in the second interval T2 and the third interval T3. Figure 4 In the example of , the pattern (0, 1, 1) is detected as the pattern indicating the rotation state. The control circuit 103 determines that it is a residual rotation as in the above-mentioned normal load case, and performs pulse control in a manner that the drive energy of the main drive pulse P1 is pulse-down.

[0074] In addition, in the state where the load increment is medium (no margin rotation), the pattern (1, 1, 1) is detected as a pattern indicating the rotation condition. The control circuit 103 maintains the level of the main drive pulse P1.

[0075] In a state where the load increment is large (critical rotation), a pattern (1, 0, 1) is detected as a pattern indicating the rotation condition. The control circuit 103 increases the level of the main drive pulse P1 (pulse up).

[0076] In the non-rotating state, the pattern (0, 0, 0) is detected as a pattern indicating the rotation condition. In the drive based only on the main drive pulse P1, the rotor of the stepping motor 105 does not rotate. The control circuit 103 performs the drive based on the correction drive pulse P2 and the pulse rise of the main drive pulse P1.

[0077] Figure 5 : is a judgment chart summarizing an example of the operation of the stepping motor control circuit of this embodiment. Figure 5 As shown, when the detection signal VRs exceeding the reference threshold voltage Vcomp is detected only in the second interval T2, or only in the second interval T2 and the third interval T3 (when the mode indicating the rotation status is the mode (0, 1, 1 / 0)), it is determined that there is a surplus rotation with a surplus in the drive energy, and the level of the main drive pulse P1 is reduced. In addition, the determination value "1 / 0" means that the determination value can be either "1" or "0".

[0078] When a detection signal VRs exceeding the reference threshold voltage Vcomp is detected in all of the first interval T1 to the third interval T3, or only in the first interval T1 and the second interval T2 (at least the first interval T1 and the second interval T2) (when the mode representing the rotation condition is the mode (1, 1, 1 / 0)), it is determined to be a residual rotation with no margin that reduces the drive energy level, and the status quo is maintained without changing the energy of the main drive pulse P1.

[0079] When the detection signal VRs exceeding the reference threshold voltage Vcomp is detected only in the first interval T1 and the third interval T3, or only in the third interval T3 (when the mode representing the rotation condition is the mode (1 / 0, 0, 1)), it is determined that the driving energy is a critical rotation of the critical energy, and the level of the main driving pulse P1 is increased without driving by the correction driving pulse P2.

[0080] In addition, when the detection signal VRs exceeding the reference threshold voltage Vcomp is detected only in the first interval T1 or is not detected in any of the first interval T1 to the third interval T3 (when the mode representing the rotation status is the mode (1 / 0, 0, 0)), it is judged as no rotation, and after being driven by the correction drive pulse P2, the level of the main drive pulse P1 is increased.

[0081] Here, we focus on the level maintenance voltage and the minimum driving voltage. The level maintenance voltage is Figure 4 The minimum drive voltage is the voltage immediately before the rotor of the stepping motor 105 stops rotating due to the main drive pulse P1.

[0082] Figure 6 1 is a diagram showing an example of the relationship among the gradation of the main driving pulse P1 , the gradation maintaining voltage, and the minimum driving voltage according to the present embodiment.

[0083] In addition, the higher the level of the main drive pulse P1, the lower the level maintenance voltage and the minimum drive voltage. However, when the level of the main drive pulse P1 is increased to a predetermined level, the main drive pulse P1 also acts after the magnetic pole of the rotor 202 passes through the inner notch of the stator 201. In the state where the main drive pulse P1 also acts 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 even if the level is further increased, the level maintenance voltage is difficult to reduce. That is, there is a trend that the higher the energy of the main drive pulse P1, the greater the voltage difference between the level maintenance voltage and the minimum drive voltage. According to this trend, there is a region of the level of the following main drive pulse P1: even if the level is reduced by two levels at a time, it will not stop rotating due to the main drive pulse P1. This region is also recorded as a region where two levels can be reduced. In addition, the following region is also recorded as a region where two levels cannot be reduced: even if the level is reduced by two levels at a time, it will not stop rotating due to the main drive pulse P1.

[0084] In addition, as described above, the inner notch of the stator 201 is the notch 205 constituting the positioning portion for determining the stop position of the rotor 202. The position where the inner notch of the stator 201 is provided corresponds to the point where the magnetic potential of the stator 201 is the maximum. The energy of the main drive pulse that continues to work even after the magnetic pole of the rotor 202 passes the point where the magnetic potential of the stator 201 is the maximum and works in a manner of attracting the rotor 202 to the end of the second quadrant is an example of the predetermined first energy.

[0085] As described above, in this embodiment, the level of the main drive pulse P1 is selected by utilizing the tendency that the voltage difference between the level maintenance voltage and the minimum drive voltage increases as the energy of the main drive pulse P1 increases.

[0086] The number of selectable levels of the main drive pulse P1 is determined in advance depending on the specification of the control circuit 103. In one example of the present embodiment, the number of selectable levels of the main drive pulse P1 is four.

[0087] Figure 6 The region R2 shown is an example of a region that can be lowered by two levels. The region R2 is a region of levels "5", "6", "7", and "8". On the other hand, the region R1 is an example of a region that cannot be lowered by two levels. The region R1 is a region of levels "1", "2", "3", and "4".

[0088] In this embodiment, the control circuit 103 selects the level of the main drive pulse P1 in a manner such that the energy difference between the levels of the main drive pulse P1 is greater than the energy difference between the levels of the main drive pulse P1 less than the energy E1, among the main drive pulses P1 with a predetermined energy E1 or more. In this embodiment, the energy E1 is the energy corresponding to the boundary between the region where two levels can be reduced and the region where two levels cannot be reduced. Figure 6 In the example of , energy E1 corresponds to energy between level "4" and level "5". Energy E1 is an example of a predetermined first energy.

[0089] In the region R2 where the voltage difference between the level maintenance voltage and the minimum driving voltage increases, one level of the main driving pulse P1 is skipped and selected. Specifically, the region R2 is a region of the level of the main driving pulse P1 where a voltage difference can be expected between the level maintenance voltage for a certain level of the main driving pulse P1 and the minimum driving voltage two levels lower than the level. Figure 6 In one example, skipping one level of the main drive pulse P1 and selecting in the region where the voltage difference between the level maintenance voltage and the minimum drive voltage increases means selecting the level of the main drive pulse P1 from levels "2", "3", "5" and "7".

[0090] In the following description, level up means changing to a level with a higher energy than the current level among the selectable levels. When the current level is a level with less than energy E1, and the next level with a higher energy than the current level is a level with energy E1 or higher, level up means going up two levels. In addition, when the current level is a level with energy E1 or higher, level up also means going up two levels. On the other hand, when the next level with a higher energy than the current level is a level with less than energy E1, level up means going up one level.

[0091] Similarly, the level reduction means changing to a level with a lower energy than the current level among the selectable levels. When the current level is a level with energy E1 or higher, the level reduction means reducing the level by two levels. When the current level is a level with energy less than E1, the level reduction means reducing the level by one level.

[0092] In the control circuit 103 of the present embodiment, the range of energy that can be supplied can be expanded without increasing the number of levels of the main drive pulse P1 compared to the related art.

[0093] As described above, the control circuit 103 selects the plurality of main drive pulses P1 such that the energy difference between the plurality of main drive pulses P1 having the predetermined energy E1 or higher is greater than the energy difference between the plurality of main drive pulses P1 having the energy less than E1.

[0094] In one example of this embodiment, the energy difference between the main drive pulses P1 below energy E1 is one level of energy difference. The energy difference between the main drive pulses P1 above energy E1 is two levels of energy difference.

[0095] In addition, regarding the energy difference between the plurality of main drive pulses P1, as long as the energy difference between the plurality of main drive pulses P1 among the main drive pulses P1 having energy E1 or more is greater than the energy difference between the plurality of main drive pulses P1 among the main drive pulses P1 having energy E1 or less, the energy difference is not limited to the above-mentioned example. For example, when the energy difference between the plurality of main drive pulses P1 among the main drive pulses P1 having energy E1 or less is an energy difference of one level, the energy difference between the plurality of main drive pulses P1 among the main drive pulses P1 having energy E1 or more may be an energy difference of three levels or more.

[0096] In addition, as described above, the range that can be lowered by two gradations is determined based on the voltage difference between the gradation sustaining voltage and the minimum driving voltage. Figure 6 The area that can be reduced by two levels is only an example and is not limited to this. Figure 6 The range of selectable levels shown is only an example and is not limited thereto. The two level regions and the range of selectable levels can be reduced according to the specifications of at least one of the stepping motor control circuit and the analog electronic clock. Figure 6 The example shown is modified.

[0097] Figure 7 103 is a flowchart showing an example of the operation of the stepping motor control circuit and the analog electronic timepiece according to the present embodiment. The operation of the stepping motor control circuit and the analog electronic timepiece mainly refers to the processing of the control circuit 103.

[0098] The oscillation circuit 101 generates a reference clock signal of a predetermined frequency. The frequency division circuit 102 divides the reference clock signal generated by the oscillation circuit 101 to generate a clock signal as a timing reference. The frequency division circuit 102 outputs the generated clock signal to the control circuit 103.

[0099] The control circuit 103 counts the time signal output by the frequency division circuit 102 to perform a timing operation. The control circuit 103 first sets the level n and the number of times N of the main drive pulse P1n to 0 (step S501). The control circuit 103 generates a control signal so that the stepping motor 105 is rotationally driven by the main drive pulse P10 with the minimum pulse width (step S502). The control circuit 103 outputs the generated control signal to the drive pulse selection circuit 104 (S503).

[0100] The driving pulse selection circuit 104 drives the stepping motor 105 to rotate by the main driving pulse P10 in response to the control signal from the control circuit 103. The stepping motor 105 is driven to rotate by the main driving pulse P10, and the hour hand 107, the minute hand 108, and the second hand 109 are driven to rotate. Thus, when the stepping motor 105 rotates normally, the analog display unit 106 displays the current time at any time by the hour hand 107, the minute hand 108, and the second hand 109.

[0101] The control circuit 103 determines whether the detection signal VRs exceeding the reference threshold voltage Vcomp is detected in the first section T1 (step S504). Here, the control circuit 103 first determines whether the detection signal VRs exceeding the predetermined reference threshold voltage Vcomp is detected based on the detection result of the detection signal VRs of the stepping motor 105 obtained by the rotation detection circuit 110. When the control circuit 103 determines that the detection signal VRs is detected, the control circuit 103 determines whether the detection time t is within the first section T1 based on the determination result of the detection time t at which the detection signal VRs is detected by the detection section determination circuit 111.

[0102] When the control circuit 103 determines that the detection signal VRs exceeding the reference threshold voltage Vcomp is not detected in the first section T1 (step S504; No), the control circuit 103 performs 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 in the first section T1 (step S504; Yes), the control circuit 103 performs the process of step S512.

[0103] The control circuit 103 determines whether the detection signal VRs exceeding the reference threshold voltage Vcomp is detected in the second interval T2 (step S505 ). The control circuit 103 performs this determination in the same manner as the determination in step S504 .

[0104] When the control circuit 103 determines that the detection signal VRs exceeding the reference threshold voltage Vcomp is not detected in 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 in the second interval T2 (step S505; Yes), the control circuit 103 executes the process of step S514.

[0105] The control circuit 103 determines whether the detection signal VRs exceeding the reference threshold voltage Vcomp is detected in the third interval T3 (step S506 ). The control circuit 103 performs this determination in the same manner as the determination in step S504 .

[0106] When the control circuit 103 determines that the detection signal VRs exceeding the reference threshold voltage Vcomp is not detected in the third interval T3 (step S506; No), the control circuit 103 performs 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 in the third interval T3 (step S506; Yes), the control circuit 103 performs the process of step S511.

[0107] When the control circuit 103 determines in step S506 that the detection signal VRs exceeding the reference threshold voltage Vcomp is not detected in the third interval T3 (no rotation in the mode (0, 0, 0)), the stepping motor 105 is driven by the correction drive pulse P2 (step S507). Then, the control circuit 103 determines whether the level n of the main drive pulse P1 is the maximum level m (step S508).

[0108] When the control circuit 103 determines that the level n of the main driving pulse P1 is not the maximum level m (step S508; No), the control circuit 103 raises the level of the main driving pulse P1 by one level and changes it to the main driving pulse P1 (n+q1) (step S510; Figure 3 Here, q1 is an integer of 1 or 2, depending on the level that can be selected as the next higher energy level relative to level n. The control circuit 103 drives with the main drive pulse P1 (n+1) in the next drive.

[0109] On the other hand, when the control circuit 103 determines that the level n of the main drive pulse P1 is the maximum level m (step S508; yes), the main drive pulse P1 is changed to a main drive pulse P1(na) whose energy is reduced by a predetermined amount (step S509). The control circuit 103 drives with the main drive pulse P1(na) in the next drive. In addition, at this time, in order to obtain a greater power saving effect, it can also be changed to the main drive pulse P10 with the minimum energy.

[0110] When the control circuit 103 determines in step S506 that the detection signal VRs exceeding the reference threshold voltage Vcomp is detected in the third interval T3 (critical rotation of the mode (0, 0, 1)), it determines whether the level n of the main drive pulse P1 is the maximum level m (step S511).

[0111] When the control circuit 103 determines that the level n of the main driving pulse P1 is not the maximum level m (step S511: No), the control circuit 103 raises the main driving pulse P1 by one level to change it to the main driving pulse P1 (n+q1) (step S510; Figure 3Here, q1 is an integer of 1 or 2, depending on the level that can be selected as the next higher energy level relative to level n. The control circuit 103 drives with the main drive pulse P1 in the next drive.

[0112] On the other hand, if the control circuit 103 determines in step S511 that the level n of the main drive pulse P1 is the maximum level m, the level cannot be changed, and therefore the main drive pulse P1 is not changed (step S513). The control circuit 103 drives with the main drive pulse P1 in the next drive.

[0113] 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 interval T1, it determines whether the detection signal VRs exceeding the reference threshold voltage Vcomp is detected in the second interval T2 (step S512). The control circuit 103 performs this determination in the same manner as in step S504.

[0114] When the control circuit 103 determines that the detection signal VRs exceeding the reference threshold voltage Vcomp is not detected in the second interval T2 (step S512; No), the process of step S506 is executed. Figure 3 Any one of the actions (b1) and (b4).

[0115] 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 interval T2 (step S512 ; Yes), the control circuit 103 executes the process of step S513 .

[0116] 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 interval T2 (no margin rotation of the pattern (1, 1, 1 / 0)), the main drive pulse P1 is not changed (step S513). The control circuit 103 drives with the main drive pulse P1 in the next drive ( Figure 3 (a1), (a2)).

[0117] On the other hand, when the control circuit 103 determines in step S505 that the detection signal VRs exceeding the reference threshold voltage Vcomp is detected within the second interval T2 (residual rotation of the mode (0, 1, 1 / 0)), it determines whether the level n of the main drive pulse P1 is the lowest level 0 (step S514).

[0118] When the control circuit 103 determines that the level n of the main drive pulse P1 is the lowest level 0 (step S514; Yes), the level cannot be changed, and therefore the main drive pulse P1 is not changed (step S518). The control circuit 103 drives with the main drive pulse P1 in the next drive.

[0119] On the other hand, when the control circuit 103 determines that the level n of the main drive pulse P1 is not the lowest level 0 (step S514; No), the control circuit 103 increases the number N by 1 (step S515). Then, the control circuit 103 determines whether the number N reaches a predetermined number (for example, 160) (step S516).

[0120] When the control circuit 103 determines that the number of times N has reached the specified number (step S516; yes), the control circuit 103 reduces the main drive pulse P1 by one level and changes it to the main drive pulse P1 (n-q2), and resets the number of times N to 0 (step S517). Here, q2 is an integer of 1 or 2 according to the level that can be selected as the next lower energy level relative to the level n. Then, the control circuit 103 executes the processing of step S502 again ( Figure 3 That is, when the processes of step S504 to step S505, step S514, and step S515 are performed consecutively a predetermined number of times, the main drive pulse P1 is reduced by one level.

[0121] 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 control circuit 103 does not change the level (step S518 ).

[0122] This concludes the description of the operation of the stepping motor control circuit and the analog electronic timepiece.

[0123] In addition, in the present embodiment, an example in which the predetermined first energy is the energy E1 is described, but the present invention is not limited thereto. The predetermined first energy may also be the energy of the main drive pulse that continues to work even after the magnetic pole of the rotor 202 passes the point at which the magnetic potential of the stator is the maximum and works in a manner that attracts the rotor 202 to the end of the second quadrant II. As described above, when the XY coordinate space centered on the rotation axis of the rotor 202 is divided into four quadrants, the second quadrant II is a quadrant (region) in which X takes a negative value and Y takes a positive value. Figure 8 In the second quadrant, II is shown. Figure 8 , the rotation behavior of the rotor 202 is an example.

[0124] The energy of the main drive pulse that continues to work even after the magnetic pole of the rotor 202 passes the point where the magnetic potential of the stator is the maximum and works in a manner that attracts the rotor 202 to the end of the second quadrant II corresponds one to one with the energy of the level included in the above-mentioned area that can be reduced by two levels. Therefore, the main drive pulse P1 having the energy of the main drive pulse that continues to work even after the magnetic pole of the rotor 202 passes the point where the magnetic potential of the stator is the maximum and works in a manner that attracts the rotor 202 to the end of the second quadrant II can be reduced by two levels.

[0125] In addition, as another example, the predetermined first energy may also refer to the energy of the main drive pulse P1 having a total length of 3.5 ms to 5.0 ms when the main drive pulse P1 is greater than the first energy. That is, the control circuit 103 may select the plurality of main drive pulses P1 in such a manner that the energy difference between the plurality of main drive pulses P1 in the main drive pulse P1 having a total length of 3.5 ms to 5.0 ms is greater than the energy difference between the plurality of main drive pulses P1 in the main drive pulse P1 having a total length of less than 3.5 ms.

[0126] The main drive pulse P1 with a total length of 3.5 ms or more and 5.0 ms or less can continue to work even after the magnetic pole of the rotor 202 passes the point where the magnetic potential of the stator is the maximum, and can work in a manner of attracting the rotor 202 to the end of the second quadrant II. Therefore, in the main drive pulse P1 with a total length of 3.5 ms or more and 5.0 ms or less, the control circuit 103 can implement two-level reduction.

[0127] On the other hand, the main drive pulse P1 with a total length exceeding 5.0 ms holds the magnetic pole of the rotor 202 at the end of the second quadrant II, making it difficult to generate the rotation detection signal Vrs. Therefore, when the main drive pulse P1 with a total length exceeding 5.0 ms is used, it is considered that it is difficult to detect the rotation state of the stepping motor 105 based on the rotation detection signal Vrs.

[0128] In addition, in this embodiment, an example in which the level is lowered when the rotation is performed a predetermined number of times (N times) continuously is described, but the present invention is not limited to this. Figure 7 In step S505 of the process shown in the figure, when the detection signal VRs exceeding the reference threshold voltage Vcomp is detected once in the second interval T2, if the main drive pulse P1 at this time is not the lowest level 0, a level reduction can also be performed. According to this structure, since it is not necessary to set the number of times N, in step S501, the number of times is not initially set and the level n is initially set to the lowest level 0. Since it is not necessary to count the number of times N, the structure is simpler than that of the present embodiment.

[0129] In addition, in this embodiment, an example is described in which the main drive pulse P1 is changed to a main drive pulse P1 with a smaller energy when the main drive pulse P1 has the maximum energy, but the present invention is not limited to this. Figure 7 When the main drive pulse P1 driven in step S508 of the illustrated process has the maximum energy, step S518 may be executed without changing the main drive pulse P1.

[0130] According to this structure, when the load of the motor is restored to a normal state by driving based on the correction drive pulse P2, and when the motor is in a state where it can be rotated and driven again by the main drive pulse P1, the next drive is driven and driven by the main drive pulse P1m with the maximum energy. Therefore, the main drive pulse P1 can be more reliably driven and driven. Therefore, when the motor is restored to a normal state, the possibility of driving based on the correction drive pulse P2 can be avoided, and energy saving can be achieved.

[0131] In addition, in the present embodiment, an example in which the detection interval is divided into three intervals (the first interval T1, the second interval T2, and the third interval T3) is described, but the present invention is not limited thereto. The detection interval may also be divided into four intervals or five or more intervals. Therefore, the control circuit 103 divides the detection interval starting immediately after driving with the main drive pulse P1 into a plurality of intervals of three or more intervals, and controls the main drive pulse P1 according to the interval in which the rotation detection circuit 110 detects a detection signal exceeding the reference threshold voltage Vcomp. By dividing the detection interval into four or more intervals, the rotation condition of the stepping motor can be detected more accurately than when the rotation condition is divided into three intervals.

[0132] As described above, the stepping motor control circuit of this embodiment has 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 interval determination circuit 111).

[0133] The rotation detection unit (in the present embodiment, the rotation detection circuit 110) detects the rotation condition of the stepping motor 105 in the detection interval of the detection signal VRs generated by the rotation of the stepping motor 105, based on whether the detection signal VRs exceeds a prescribed reference threshold voltage within a prescribed detection interval (in the present embodiment, one or more of the first interval T1, the second interval T2, and the third interval T3).

[0134] The control unit (in this embodiment, the control circuit 103, the drive pulse selection circuit 104 and the detection interval judgment circuit 111) drives and controls the stepping motor 105 through any one of a plurality of main drive pulses P1 with different energies according to the detection result of the rotation detection unit (in this embodiment, the rotation detection circuit 110).

[0135] The control unit (in the present embodiment, the control circuit 103, the drive pulse selection circuit 104 and the detection interval determination circuit 111) selects a plurality of main drive pulses P1 in such a manner that the energy difference between a plurality of main drive pulses P1 (in the present embodiment, main drive pulses of levels "5" and "7") among the main drive pulses P1 having a predetermined first energy (in the present embodiment, energy E1) or above is greater than the energy difference between a plurality of main drive pulses P1 (in the present embodiment, main drive pulses of levels "2" and "3") among the main drive pulses P1 having a energy less than the first energy (in the present embodiment, energy E1).

[0136] According to this structure, in the stepping motor control circuit of this embodiment, since the range of energy that can be supplied can be expanded without increasing the number of levels of the main drive pulse P1 compared to the past, the drive range can be expanded even when the number of selectable main drive pulse levels is limited.

[0137] In addition, in the present embodiment, the pulse width is varied to change the energy of each main drive pulse P1, but the drive energy can also be changed by changing the pulse voltage, etc. In addition, the main drive pulse P1 can also be configured to be a comb-shaped chopped waveform, and the number of chopped waves and the duty cycle can be changed to change the drive energy of the main drive pulse P1.

[0138] Furthermore, the stepping motor control circuit of the present embodiment can be applied to a stepping motor for driving a calendar of various analog electronic watches with calendar functions in addition to the time hands.

[0139] Furthermore, although an electronic timepiece is described as an application example of the stepping motor, the stepping motor can be applied to electronic devices using a motor.

[0140] As mentioned above, one embodiment of the present invention has been described in detail with reference to the drawings, but the specific structure is not limited to the above structure, and various design changes can be made within the scope not departing from the gist of the present invention.

Claims

1. A stepper motor control circuit, the stepper motor control circuit having: a rotation detection unit that detects the rotation status of the stepping motor in a detection interval for detecting a detection signal generated by the rotation of the stepping motor, based on whether the detection signal exceeds a predetermined reference threshold voltage within a predetermined detection interval; and a control unit that drives and controls the stepping motor by using any one of a plurality of main drive pulses having different energies according to the detection result of the rotation detection unit, The control unit selects the plurality of main drive pulses such that the energy difference between the plurality of main drive pulses of a predetermined first energy or higher is greater than the energy difference between the plurality of main drive pulses of a predetermined first energy or higher.

2. The stepper motor control circuit according to claim 1, wherein: The first energy refers to the energy of the main drive pulse which continues to act even after the magnetic pole of the rotor 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.

3. The stepper motor control circuit according to claim 1, wherein: The first energy is energy that allows a main drive pulse having a total length of 3.5 ms to 5.0 ms.

4. The stepper motor control circuit according to claim 1, wherein: The control unit changes the main drive pulse to a main drive pulse with a smaller energy when it is determined that the main drive pulse is a surplus rotation with a surplus drive energy.

5. The stepper motor control circuit according to claim 1, wherein: The control unit divides the detection section starting immediately after driving with the main drive pulse into a plurality of sections of three or more sections, and controls the main drive pulse according to a section in which the rotation detector detects a detection signal exceeding the reference threshold voltage.

6. An analog electronic timepiece, comprising: a stepping motor for rotating and driving a time hand; and a stepping motor control circuit for controlling the stepping motor, wherein: The stepping motor control circuit is the stepping motor control circuit according to any one of claims 1 to 5.

Images