Stepping Motor Control Device, Movement, Clock, and Stepping Motor Control Method

Abstract

To detect a position of a pointer.SOLUTION: A stepping motor control device includes: a drive unit for driving a stepping motor having a rotor for rotating a pointer and a coil for generating magnetic flux for rotating the rotor; a control unit for outputting a drive pulse for rotating the rotor and a swing pulse for swinging the rotor to the drive unit; a voltage detection unit for detecting an induced voltage generated in the coil when the rotor vibrates; and a determination unit for determining a mechanical load applied to the rotor based on results detected by the voltage detection unit.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a stepping motor control device, a movement, a clock, and a stepping motor control method.

Background Art

[0002] Conventionally, there has been a method for detecting the position of the hands of a clock. For example, a technique has been proposed in which a stepping motor is driven by drive pulses during normal driving, and the rotation state of the rotor is detected by an induced voltage (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the conventional technology as described in Patent Document 1, for detecting the rotation state of the rotor, after applying normal drive pulses to the stepping motor, the rotor vibrates at a speed of a certain level or higher and generates an induced voltage equal to or higher than a predetermined threshold voltage. However, depending on the motor, it is difficult to generate an induced voltage, and there has been a problem that it may be difficult to detect the rotation state.

[0005] The present invention has been made in view of such a situation, and an object thereof is to detect the position of the hands.

Means for Solving the Problems

[0006] A stepping motor control device according to an aspect of the present invention includes a drive unit that drives a stepping motor including a rotor that rotates a pointer and a coil that generates a magnetic flux for rotating the rotor, a control unit that outputs a drive pulse for rotating the rotor and a swing pulse for swinging the rotor to the drive unit, a voltage detection unit that detects an induced voltage generated in the coil when the rotor vibrates, and a determination unit that determines a mechanical load applied to the rotor based on a result detected by the voltage detection unit. Before outputting the drive pulse, the control unit outputs the corresponding swing pulse, and the determination unit determines the mechanical load based on the result of detecting the rotation associated with the output of the swing pulse. 。

[0007] Further, in the stepping motor control device according to an aspect of the present invention, the control unit outputs the drive pulse after a predetermined period has elapsed after outputting the swing pulse.

[0008] Further, in the stepping motor control device according to an aspect of the present invention, the determination unit determines whether a first gear that rotates based on the rotation of the rotor is in contact with the load teeth of a second gear having load teeth as the mechanical load.

[0009] Further, in the stepping motor control device according to an aspect of the present invention, the control unit controls the energy for driving the stepping motor according to the mechanical load determined by the determination unit.

[0010] Further, in the stepping motor control device according to an aspect of the present invention, the control unit controls the energy for driving the stepping motor by controlling the output time of the drive pulse.

[0011] Further, in the stepping motor control device according to an aspect of the present invention, the control unit controls the energy for driving the stepping motor by controlling an excitation method of the stepping motor.

[0012] Also, in the stepping motor control device according to one aspect of the present invention, the control unit controls the energy for driving the stepping motor by controlling the duty ratio of the drive pulse.

[0013] Also, in the stepping motor control device according to one aspect of the present invention, the control unit controls the energy for driving the stepping motor by controlling the voltage of the drive pulse.

[0014] Also, in the stepping motor control device according to one aspect of the present invention, the rocking pulse has energy for rotating the rotor in a first rotation direction, a first rocking pulse for rocking the rotor, or, after outputting the first rocking pulse, has energy for rotating the rotor in a second rotation direction, and is either a second rocking pulse for rocking the rotor.

[0015] Also, in the stepping motor control device according to one aspect of the present invention, the first rotation direction is the normal rotation direction, and the second rotation direction is the opposite direction to the first rotation direction.

[0016] Also, in the stepping motor control device according to one aspect of the present invention, when the control unit outputs the rocking pulse according to a predetermined period in which the drive pulse is output, the control unit outputs the first rocking pulse, and when the control unit outputs the rocking pulse at a predetermined timing not according to the predetermined period in which the drive pulse is output, the control unit outputs the first rocking pulse and the second rocking pulse.

[0017] Also, in the stepping motor control device according to one aspect of the present invention, the determination unit determines the mechanical load received by the rotor based on whether or not the voltage value detected by the voltage detection unit exceeds a predetermined threshold value.

[0018] Also, in the stepping motor control device according to one aspect of the present invention, the determination unit determines the mechanical load received by the rotor based on whether the generation timing of the voltage value detected by the voltage detection unit is within a predetermined period.

[0019] In the stepping motor control device according to one aspect of the present invention, the control unit has a swing pulse output mode for outputting the swing pulse and a swing pulse non-output mode for not outputting the swing pulse.

[0020] Also, in the stepping motor control device according to one aspect of the present invention, when the drive pulse is output from the control unit, the drive unit drives the stepping motor with a first voltage, and when the swing pulse is output from the control unit, the drive unit drives the stepping motor with a second voltage lower than the first voltage.

[0021] Also, in the stepping motor control device according to one aspect of the present invention, when the mechanical load received by the rotor determined by the determination unit is smaller than a predetermined threshold, among the drive pulses of a plurality of ranks with different energies, the drive pulse of a rank larger than the immediately preceding applied drive pulse is applied, and when a result that the mechanical load received by the rotor determined by the determination unit is larger than a predetermined threshold is continuously obtained a predetermined number of times or more, among the drive pulses of a plurality of ranks with different energies, the drive pulse of a rank smaller than the immediately preceding applied drive pulse is applied.

[0022] Also, in the stepping motor control device according to one aspect of the present invention, when a gear having load teeth makes one revolution, the control unit selects which rank of the swing pulses of a plurality of ranks with different energies to apply based on the number of times it is determined by the determination unit that the mechanical load received by the rotor is larger than a predetermined threshold.

[0023] Also, in the stepping motor control device according to one aspect of the present invention, while the control unit controls the rank of the swing pulse, it does not control the drive pulse.

[0024] A movement according to one aspect of the present invention includes the above-described stepping motor control device and the stepping motor.

[0025] A clock according to one aspect of the present invention includes the above-described movement.

[0026] A stepping motor control method according to one aspect of the present invention rotates a rotor that rotates a pointer and a coil that generates a magnetic flux for rotating the rotor by applying a drive pulse to a stepping motor including the rotor and the coil. And The rotor is swung by applying a swing pulse to the stepping motor, an induced voltage generated in the coil when the rotor vibrates is detected, a mechanical load received by the rotor is determined based on the detected result, and before the drive pulse is output, the corresponding swing pulse is output, and the mechanical load is determined based on the result of detection by the voltage detection unit of the rotation accompanying the output of the swing pulse.

Advantages of the Invention

[0027] According to the present invention, the position of the pointer can be detected.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

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Figure 23

Embodiments for Carrying Out the Invention

[0029] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals are given to configurations having the same or similar functions. And the redundant description of those configurations may be omitted.

[0030] [First Embodiment] Generally, a mechanical body including a driving part of a watch is called a "movement". The state in which a dial and hands are attached to this movement and placed in a watch case to make a finished product is called the "complete" of the watch. Of the two sides of the base plate constituting the watch substrate, the side with the glass of the watch case (that is, the side with the dial) is called the "back side" of the movement. Also, of the two sides of the base plate, the side with the case back cover of the watch case (that is, the side opposite to the dial) is called the "front side" of the movement.

[0031] FIG. 1 is an external view of a watch according to the first embodiment. As shown in Fig. 1, the complete set of the clock 1 of the present embodiment includes a movement 4 (a clock movement), a dial 5 with scales, an hour hand 6 (a pointer), a minute hand 7, a second hand 8, and a 24-hour hand 9, inside a clock case 2 composed of a case back cover and glass 3 (not shown). An aperture 5a for clearly showing the date characters 46a displayed on a date wheel 46 (to be described later) is formed in the dial 5. Thus, the clock 1 can be used to check the date in addition to the time.

[0032] Fig. 2 is a plan view of the front side of the movement according to the first embodiment. Fig. 3 is a plan view of the back side of the movement according to the first embodiment. As shown in Figs. 2 and 3, the movement 4 includes a base plate 11, a date wheel retainer 13, a first motor 20A, a second motor 20B, a first gear train group 30, and a second gear train group 50. The base plate 11 constitutes the substrate of the movement 4. The date wheel retainer 13 is disposed on the back side of the base plate 11.

[0033] As shown in Fig. 2, the first motor 20A and the second motor 20B are stepping motors each having a stator 21 and a rotor 22. Each of the first motor 20A and the second motor 20B rotates the rotor 22 by 180° in one step. The first motor 20A generates power for rotating the hour hand 6, the 24-hour hand 9, and the date wheel 46 (all shown in Fig. 1). The second motor 20B generates power for rotating the minute hand 7 and the second hand 8 (all shown in Fig. 1). Teeth are formed on the rotor 22 of each of the first motor 20A and the second motor 20B.

[0034] Fig. 4 is a plan view showing a part of the movement according to the first embodiment, as viewed from the front side of the first gear train group. As shown in Figs. 3 and 4, the first gear train group 30 has gears that rotate based on the rotation of the rotor 22 of the first motor 20A. The first gear train group 30 includes a time gear train 31 that transmits the rotation of the rotor 22 of the first motor 20A to the hour hand 6, and a calendar gear train 41 that transmits the rotation of the rotor 22 of the first motor 20A to the 24-hour hand 9 (shown in Fig. 1) and the date wheel 46.

[0035] As shown in Fig. 4, the time wheel train 31 includes a first time intermediate wheel 32, a second time intermediate wheel 33, a third time intermediate wheel 34, and a tub wheel 35. The first time intermediate wheel 32 is rotatably supported by the floor 11 (see Fig. 2). The first time intermediate wheel 32 has a first time intermediate gear 32a and a first time intermediate kana 32b. The first time intermediate gear 32a meshes with the kana of the rotor 22 of the first motor 20A. The first time intermediate wheel 32 rotates with a speed reduction ratio of 6 with respect to the rotor 22. That is, the first time intermediate wheel 32 rotates once every six rotations of the rotor 22 of the first motor 20A.

[0036] The second time intermediate wheel 33 is rotatably supported by the floor 11. The second time intermediate wheel 33 has a second time intermediate gear 33a and a second time intermediate kana 33b. The second time intermediate gear 33a meshes with the first time intermediate kana 32b of the first time intermediate wheel 32. The second time intermediate wheel 33 is a driven gear with respect to the first time intermediate wheel 32. The second time intermediate wheel 33 rotates with a speed reduction ratio of 7.5 with respect to the first time intermediate wheel 32. That is, the second time intermediate wheel 33 rotates with a speed reduction ratio of 45 with respect to the rotor 22 of the first motor 20A.

[0037] The third time intermediate wheel 34 is rotatably supported by the floor 11. The third time intermediate wheel 34 has a third time intermediate gear 34a and a third time intermediate kana 34b (first gear). The third time intermediate gear 34a meshes with the second time intermediate kana 33b of the second time intermediate wheel 33. The third time intermediate wheel 34 is a driven gear with respect to the second time intermediate wheel 33. The third time intermediate wheel 34 rotates with a speed reduction ratio of 8 with respect to the second time intermediate wheel 33. That is, the third time intermediate wheel 34 rotates with a speed reduction ratio of 360 with respect to the rotor 22 of the first motor 20A.

[0038] The barrel wheel 35 is rotatably externally inserted into a central pipe (not shown) held by the floor board 11. The barrel wheel 35 is pressed from the back side via a needle seat by the sun wheel retainer 13 (see FIG. 3). The end on the back side of the barrel wheel 35 protrudes from the sun wheel retainer 13 to the back side. The hour hand 6 (see FIG. 1) is attached to the end on the back side of the barrel wheel 35. The barrel wheel 35 has a barrel gear 35a. The barrel gear 35a meshes with the third intermediate hour gear 34a of the third intermediate hour wheel 34. The barrel wheel 35 is a driven gear with respect to the third intermediate hour wheel 34. The barrel wheel 35 rotates with a reduction ratio of 1 with respect to the third intermediate hour wheel 34. That is, the barrel wheel 35 rotates with a reduction ratio of 360 with respect to the rotor 22 of the first motor 20A.

[0039] The calendar wheel train 41 includes the first intermediate hour wheel 32, the second intermediate hour wheel 33, and the third intermediate hour wheel 34 described above, the 24-hour wheel 42, and the daily rotation intermediate wheel 43. The 24-hour wheel 42 is rotatably supported by the floor board 11. The shaft portion of the 24-hour wheel 42 protrudes from the sun wheel retainer 13 to the back side. The 24-hour hand 9 (see FIG. 1) is attached to the end on the back side of the shaft portion. The 24-hour wheel 42 has a 24-hour gear 42a (second gear). The 24-hour gear 42a meshes with the third intermediate kana 34b of the third intermediate hour wheel 34. The 24-hour wheel 42 is a driven gear with respect to the third intermediate hour wheel 34. The 24-hour wheel 42 rotates with a reduction ratio of 2 with respect to the third intermediate hour wheel 34. That is, the 24-hour wheel 42 rotates with a reduction ratio of 720 with respect to the rotor 22 of the first motor 20A.

[0040] The daily rotation intermediate carriage 43 is rotatably supported on the floor 11. The rotation center of the daily rotation intermediate carriage 43 is provided at a position offset by an angle of less than 180° from the rotation center of the 3 o'clock intermediate carriage 34 around the rotation center of the 24 o'clock carriage 42. That is, the rotation center of the daily rotation intermediate carriage 43 is provided at a position deviated from the straight line passing through the rotation center of the 24 o'clock carriage 42 and the rotation center of the 3 o'clock intermediate carriage 34 in plan view. The daily rotation intermediate carriage 43 has a daily rotation intermediate gear 43a and a disk carriage 43b. The daily rotation intermediate gear 43a meshes with the 24 o'clock intermediate gear 42a. The daily rotation intermediate carriage 43 is a driven carriage with respect to the 24 o'clock carriage 42. The daily rotation intermediate carriage 43 rotates with a reduction ratio of 1 with respect to the 24 o'clock carriage 42. That is, the daily rotation intermediate carriage 43 rotates with a reduction ratio of 720 with respect to the rotor 22 of the first motor 20A. The disk carriage 43b overlaps the daily rotation intermediate gear 43a. The disk carriage 43b is provided with feed teeth 43c. The feed teeth 43c project radially outward from the outer peripheral surface of the disk carriage 43b.

[0041] The daily rotation carriage 44 is rotatably supported on the floor 11. The daily rotation carriage 44 has a daily rotation gear 44a. The daily rotation gear 44a is formed so as to be able to mesh with the feed teeth 43c of the daily rotation intermediate carriage 43. The daily rotation carriage 44 rotates when the feed teeth 43c of the daily rotation intermediate carriage 43 enter the rotation locus of the daily rotation gear 44a and mesh therewith. For this reason, the daily rotation carriage 44 rotates intermittently due to the rotation of the daily rotation intermediate carriage 43. The daily rotation carriage 44 rotates the daily carriage 46.

[0042] The date wheel 46 is a ring-shaped member rotatably attached to the floor board 11. The date wheel 46 is pressed from the back side by the date wheel retainer 13 (see Fig. 3). On the back surface of the date wheel 46, date characters 46a (see Fig. 1), which are date information, are displayed along the circumferential direction. The date wheel 46 displays the date information by exposing the date characters 46a through the date window 5a of the dial plate 5. A plurality of internal teeth 46b are formed over the entire inner peripheral edge of the date wheel 46. The internal teeth 46b mesh with the date driving gear 44a. The date wheel 46 rotates in conjunction with the rotation of the date driving wheel 44. Therefore, the date wheel 46 rotates intermittently due to the rotation of the date intermediate wheel 43. The rotation direction position of the date wheel 46 is regulated by the jumper 47. The jumper 47 restricts the rotation of the date wheel 46 by engaging the claw at the tip with the internal teeth 46b of the date wheel 46.

[0043] As shown in Fig. 2, the second gear train group 50 has a gear that rotates based on the rotation of the rotor 22 of the second motor 20B. The second gear train group 50 includes a front gear train 51 that transmits the rotation of the rotor 22 of the second motor 20B to the second hand 8 and the minute hand 7 (both see Fig. 1). The front gear train 51 includes a fourth intermediate wheel 52, a fourth wheel 53, a third wheel 54, and a second wheel 55.

[0044] The fourth intermediate wheel 52 is rotatably supported by the floor board 11. The fourth intermediate wheel 52 has a fourth intermediate gear 52a and a fourth intermediate kana 52b. The fourth intermediate gear 52a meshes with the kana of the rotor 22 of the second motor 20B. The fourth intermediate wheel 52 rotates with a reduction ratio of 6 with respect to the rotor 22 of the second motor 20B.

[0045] The fourth wheel 53 is rotatably arranged with respect to the floor 11. The fourth wheel 53 has a fourth lens (not shown), a fourth gear 53b assembled to the fourth lens, and a fourth kana (not shown) formed on the fourth lens. The fourth lens is inserted inside the second lens described later. The end on the back side of the fourth lens has the second hand 8 (see FIG. 1) attached thereto. The fourth gear 53b meshes with the fourth intermediate kana 52b. The fourth wheel 53 is a driven gear with respect to the fourth intermediate wheel 52. The fourth wheel 53 rotates with a reduction ratio of 10 with respect to the fourth intermediate wheel 52. That is, the fourth wheel 53 rotates with a reduction ratio of 60 with respect to the rotor 22 of the second motor 20B.

[0046] The third wheel 54 is rotatably supported by the floor 11. The third wheel 54 includes a third gear 54a and a third kana (not shown). The third gear 54a meshes with the fourth kana. The third wheel 54 is a driven gear with respect to the fourth wheel 53. The third wheel 54 rotates with a reduction ratio of 20 with respect to the fourth wheel 53. That is, the third wheel 54 rotates with a reduction ratio of 400 with respect to the rotor 22 of the second motor 20B.

[0047] The second wheel 55 is rotatably supported by a central pipe (not shown). The second wheel 55 has a second lens (not shown) and a second gear 55b assembled to the second lens. The second lens is formed in a cylindrical shape and is inserted inside the central pipe. The minute hand 7 (see FIG. 1) is attached to the end on the back side of the second lens. The second gear 55b meshes with the third kana. The second wheel 55 is a driven gear with respect to the third wheel 54. The second wheel 55 rotates with a reduction ratio of 9 with respect to the third wheel 54. That is, the second wheel 55 rotates with a reduction ratio of 3600 with respect to the rotor 22 of the second motor 20B.

[0048] FIG. 5 is a plan view of the 24-hour gear according to the first embodiment. As shown in FIG. 5, the 24-hour gear 42a has a plurality of teeth 60 and an elastic portion 65. The plurality of teeth 60 includes standard teeth 61 and a first load tooth 62A as a load tooth 62. The standard teeth 61 are all the teeth among the plurality of teeth 60 except the first load tooth 62A. The standard teeth 61 are teeth of a general gear, and are teeth formed in an arc tooth profile, an involute tooth profile, a cycloid tooth profile, or the like. The first load tooth 62A is one of the plurality of teeth 60 of the 24-hour gear 42a. The first load tooth 62A is arranged on one side of the outer periphery of the 24-hour gear 42a so as not to contact the third-hour intermediate kana 34b at equal intervals when the 24-hour gear 42a is rotated. The first load tooth 62A is formed to be elastically displaceable by being supported by the elastic portion 65.

[0049] The elastic portion 65 is provided for each load tooth 62. The elastic portion 65 is a cantilever beam having a load tooth 62 at its tip and formed to be bendable. The elastic portion 65 includes a first elastic portion 65A having the first load tooth 62A. The first elastic portion 65A is a portion between a first slit 67 and a second slit 68 formed in the 24-hour gear 42a. The first slit 67 extends radially inward from one tooth groove adjacent to the first load tooth 62A and then extends in one circumferential direction. The second slit 68 extends along the first slit 67 from the other tooth groove adjacent to the first load tooth 62A. Thereby, the first elastic portion 65A extends with a substantially constant width and is formed to be elastically deformable so as to displace the first load tooth 62A at the tip in the radial direction.

[0050] Here, a first standard tooth 61A and a second standard tooth 61B among the plurality of standard teeth 61 are defined as follows. The first standard tooth 61A is adjacent to the first load tooth 62A on the downstream side in the forward rotation direction N (a predetermined rotation direction) of the 24-hour gear 42a. The second standard tooth 61B is adjacent to the first load tooth 62A on the upstream side in the forward rotation direction N.

[0051] The distance between the first load tooth 62A and the first standard tooth 61A is narrower than the distance between the first load tooth 62A and the second standard tooth 61B. The width of the tooth groove between the first load tooth 62A and the first standard tooth 61A is smaller than the tooth thickness of the tooth of the third intermediate kana 34b. Note that the width of the tooth groove between a pair of adjacent teeth 60 is the distance between a pair of teeth 60 on the pitch circle of the 24-hour gear 42a. The tooth thickness of the tooth 60 is the thickness of the tooth 60 on the pitch circle of the 24-hour gear 42a. Thereby, when the tooth of the third intermediate kana 34b enters the tooth groove between the first load tooth 62A and the first standard tooth 61A, it contacts the first load tooth 62A. The width of the tooth groove between the first load tooth 62A and the second standard tooth 61B is larger than the tooth thickness of the tooth of the third intermediate kana 34b. Thereby, the tooth of the third intermediate kana 34b can enter the tooth groove between the first load tooth 62A and the second standard tooth 61B without contacting the first load tooth 62A.

[0052] Here, the action of the load tooth 62 will be described. In the following description, unless otherwise specified, it is assumed that the 24-hour gear 42a is rotating in the forward rotation direction N. The teeth of the third intermediate kana 34b contact each tooth 60 of the 24-hour gear 42a from the upstream side in the forward rotation direction N.

[0053] When the tooth 60 engaged with the third intermediate kana 34b alternates to the first standard tooth 61A, the tooth of the third intermediate kana 34b enters the tooth groove between the first standard tooth 61A and the first load tooth 62A. At this time, the tooth of the third intermediate kana 34b contacts the first load tooth 62A before and after contacting the first standard tooth 61A, and elastically displaces the first load tooth 62A so as to widen the width of the tooth groove between the first standard tooth 61A and the first load tooth 62A. Thereby, energy loss due to the elastic displacement of the first load tooth 62A occurs in the calendar wheel train 41. After that, when the tooth 60 engaged with the third intermediate kana 34b alternates to the first load tooth 62A, the first load tooth 62A gradually returns toward the initial position. Then, when the tooth 60 engaged with the third intermediate kana 34b alternates from the first load tooth 62A to the second standard tooth 61B, the tooth of the third intermediate kana 34b completely separates from the first load tooth 62A in the tooth groove between the first load tooth 62A and the second standard tooth 61B, and the first load tooth 62A returns to the initial position.

[0054] As described above, when the first load tooth 62A of the 24-hour gear 42a contacts the third intermediate kana 34b, energy loss occurs in the calendar wheel train 41. That is, energy loss occurs in the calendar wheel train 41 twice for each rotation of the 24-hour gear 42a. When energy loss occurs in the calendar wheel train 41, the load received by the rotor 22 of the first motor 20A fluctuates. As a result, the load tooth 62 can cause fluctuations in the load received by the rotor 22. Note that the fluctuations in the load caused by the load tooth 62 only need to be different from the load when the standard tooth 61 contacts the third intermediate kana 34b. Hereinafter, the load received by the rotor 22 may be referred to as a rotational load.

[0055] [Functional Configuration of Watch] FIG. 6 is a diagram showing an example of the functional configuration of a watch according to the first embodiment. The functional configuration of the watch 1 will be described with reference to this figure. The watch 1 includes an oscillation circuit 101, a frequency division circuit 102, a control circuit (control unit) 103, a determination circuit (determination unit) 104, a voltage detection circuit (voltage detection unit) 105, a motor drive circuit (drive unit) 106, a stepping motor 107, a watch case 2, a movement 4, an hour hand 6, a minute hand 7, a second hand 8, and a date window 5a. Hereinafter, the oscillation circuit 101, the frequency division circuit 102, the control circuit 103, the determination circuit 104, the voltage detection circuit 105, and the motor drive circuit 106 will also be referred to as a stepping motor control circuit (stepping motor control device) 100. Further, the stepping motor control circuit 100 and the stepping motor 107 will also be referred to as a pointer drive unit 110.

[0056] The oscillation circuit 101 generates a signal having a predetermined frequency and transmits the generated signal to the frequency division circuit 102. The frequency division circuit 102 divides the signal received from the oscillation circuit 101 to generate a clock signal serving as a reference for timekeeping, and transmits the generated clock signal to the control circuit 103. The control circuit 103 transmits control signals to each part of the watch 1 based on the clock signal and the like received from the frequency division circuit 102, and controls the operations of each part of the watch 1.

[0057] The motor drive circuit 106 acquires a control signal from the control circuit 103 and drives the stepping motor 107 based on the acquired control signal. The stepping motor 107 is driven by the motor drive circuit 106 and rotates the hour hand 6, minute hand 7, and second hand 8 via the wheel train. The voltage detection circuit 105 detects the induced voltage generated in the coil when the stepping motor 107 vibrates. The voltage detection circuit 105 transmits the detected induced voltage to the determination circuit 104. The determination circuit 104 determines the mechanical load received by the rotor provided in the stepping motor 107 based on the value of the induced voltage detected by the voltage detection circuit 105. For example, the determination circuit 104 determines the mechanical load received by the rotor based on whether the voltage value detected by the voltage detection circuit 105 exceeds a predetermined threshold value.

[0058] [Configuration of the pointer drive unit] FIG. 7 is a diagram showing an example of the configuration of the pointer drive unit 110 according to the first embodiment. The stepping motor 107 includes a stator 201, a rotor 202, a through hole 203 for accommodating the rotor, an inner notch 204, an inner notch 205, an outer notch 206, an outer notch 207, a magnetic core 208, and a coil 209. Hereinafter, the through hole 203 for accommodating the rotor will also be referred to as the through hole for the rotor.

[0059] The magnetic core 208 is a member made of a magnetic material and is joined to both ends of the stator 201. The coil 209 is wound around the magnetic core 208, one end is connected to the terminal OUT1, and the other end is connected to the terminal OUT2. The coil 209 generates a magnetic flux when a drive current i flows through it. The stator 201 is a member made of a magnetic material. The stator 201 applies the magnetic flux generated by the coil 209 to the rotor 202.

[0060] The rotor 202 is formed in a cylindrical shape and is inserted into a rotor accommodation through-hole 203 formed in the stator 201 in a rotatable state. That is, the stepping motor 107 includes a stator 201 provided with a rotor accommodation through-hole 203, a rotor 202 rotatably disposed in the rotor accommodation through-hole 203, and a coil 209 provided in the stator 201. Further, since the rotor 202 is magnetized, it has an N pole and an S pole. In the following description, the axis from the S pole to the N pole of the rotor 202 is also referred to as the magnetic pole axis A, and the direction from the S pole to the N pole of the magnetic pole axis A is also referred to as the positive direction of the magnetic pole axis A (or simply the direction of the magnetic pole axis A).

[0061] When the rotor 202 rotates in the forward rotation direction, the pointer 155 is rotated clockwise via the gear train, and when the rotor 202 rotates in the reverse rotation direction, the pointer 155 is rotated counterclockwise via the gear train. That is, the rotor 202 rotates in the forward rotation direction for rotating the pointer 155 clockwise and in the reverse rotation direction which is opposite to the forward rotation direction for rotating the pointer 155.

[0062] The inner notch 204 and the inner notch 205 are notches formed in the wall surface of the rotor accommodation through-hole 203, and determine the stop position of the rotor 202 with respect to the stator 201. That is, for example, when the coil 209 is not excited, the rotor 202 stops at a position where the magnetic pole axis is orthogonal to the line segment connecting the inner notch 204 and the inner notch 205.

[0063] The outer notch 206 and the outer notch 207 are notches formed on the inner and outer sides of the stator 201 which are curved, respectively. A saturable portion 210 is formed between the outer notch 206 and the rotor accommodation through-hole 203, and a saturable portion 211 is formed between the outer notch 207 and the rotor accommodation through-hole 203. The saturable portion 210 and the saturable portion 211 are portions that are not magnetically saturated by the magnetic flux of the rotor 202 and become magnetically saturated and have a large magnetic resistance when the coil 209 is excited.

[0064] [Drive of the stepping motor] The motor drive circuit 106 generates a drive current i by applying a drive pulse between the terminals (the first terminal OUT1 and the second terminal OUT2) of the coil 209. The stepping motor control device 100 rotates the rotor 202 in a certain direction (for example, the forward rotation direction) by inverting the direction of the drive current i supplied to the coil 209 according to the direction of the magnetic pole axis A at the stop position of the rotor 202.

[0065] As an example, the drive in the forward rotation direction will be described. When the stepping motor control device 100 supplies a drive pulse between the first terminal OUT1 and the second terminal OUT2 of the coil 209, a magnetic flux is generated in the stator 201. As a result, the saturable portions 210 and 211 are saturated and the magnetic resistance increases. Thereafter, due to 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 counterclockwise and stops stably. By this rotation of about 180 degrees, the pointer 155 of the clock 1 can move by one scale of a specified amount. The operation of the specified amount may be referred to as one step. A gear train having an appropriate reduction ratio is appropriately arranged between the rotor 202 and the pointer 155 so as to achieve the operation of the specified amount. In an example of the present embodiment, the pointer 155 moves by one second by the operation of one step.

[0066] When the rotor 202 is in the state shown in FIG. 7 and the stepping motor control device 100 supplies a drive pulse between the first terminal OUT1 and the second terminal OUT2 of the coil 209, a current flows through the coil 209. In this example, when a pulse in which the first terminal OUT1 is at a high potential and the second terminal OUT2 is at a low potential (hereinafter referred to as the positive direction) is applied, a current flows in the direction of the current i. When a current flows through the coil 209, a magnetic flux is generated in the stator 201. Due to this magnetic flux, the rotor 202 rotates approximately 180 degrees counterclockwise and stops stably.

[0067] When the rotor 202 is in a state rotated approximately 180 degrees from the state shown in FIG. 7, if the stepping motor control device 100 applies a pulse in which the first terminal OUT1 is at a low potential and the second terminal OUT2 is at a high potential (hereinafter referred to as the negative direction), a magnetic flux opposite to the case where a positive direction pulse is applied is generated in the stator 201. As a result, the saturable portions 210 and 211 are first saturated, and 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 rotates approximately 180 degrees counterclockwise and stops stably. In this way, by supplying signals (alternating signals) with different polarities to the coil 209, the rotor 202 continuously rotates approximately 180 degrees counterclockwise.

[0068] [Oscillation Pulse and Drive Pulse] FIG. 8 is a diagram showing an example of an oscillation pulse and a drive pulse in the first embodiment. FIG. 8(A) is a timing chart for explaining the timing at which the oscillation pulse and the drive pulse are applied, and FIG. 8(B) is a diagram for explaining the angle of the rotor 202. In the explanation of FIG. 8(A), the horizontal axis indicates time, “Out1” indicates the magnitude of the voltage applied to the first terminal OUT1 at each time, and “Out2” indicates the magnitude of the voltage applied to the second terminal OUT2 at each time. Also, in the explanation of FIG. 8(B), with the position of the magnetic pole axis A described with reference to FIG. 7 being 0 degrees and the angle of rotation of the magnetic pole axis A counterclockwise being defined as the positive rotation angle, the rotational position of the rotor 202 will be described. The control from time t11 to time t21 is control for rotating the rotor 202 clockwise from 0 degrees to 180 degrees, and the control from time t21 to time t29 is control for rotating the rotor 202 clockwise from 180 degrees to 0 degrees.

[0069] The control circuit 103 rotates the rotor 202 by outputting a drive pulse to the motor drive circuit 106, and oscillates the rotor 202 by outputting an oscillation pulse to the motor drive circuit 106. Hereinafter, the oscillation pulse and the drive pulse will be described respectively.

[0070] From time t11 to time t12, the stepping motor control device 100 applies a positive pulse to the second terminal OUT2. When the positive pulse continues to be applied to the second terminal OUT2, the rotor 202 stops at the position rotated by -45 degrees. When the stepping motor control device 100 stops applying the pulse at time t12, the rotor 202 is pulled back to the 0-degree position and stops. Here, when the rotor 202 returns from the -45-degree position to the 0-degree position, due to inertia, it rotates at least once counterclockwise to a position with a positive rotation angle and rotates clockwise to a position with a negative rotation angle. The rotor 202 repeats rotating counterclockwise and rotating clockwise. That is, the rotor 202 vibrates and stops at the 0-degree position as the vibration decays.

[0071] Note that the pulse applied from time t11 to time t12 is not a pulse for the purpose of rotating the rotor 202 by approximately 180 degrees, but a pulse for detecting the vibration state of the rotor 202 by vibrating the rotor 202. Hereinafter, the pulse for the purpose of vibrating the rotor 202 is distinguished from the normal drive pulse and is referred to as a rocking pulse.

[0072] Note that the time during which the rocking pulse is applied only needs to be a time sufficient for the rotor 202 to vibrate, and it is not necessary for the pulse to be applied until the rotor 202 stops at the -45-degree rotation position.

[0073] From time t12 to time t15, the stepping motor control device 100 determines the mechanical load received by the rotor 202 by applying the rocking pulse. Specifically, based on the voltage detected by the voltage detection circuit 105, the determination circuit 104 determines the mechanical load received by the rotor 202. Note that the determination circuit 104 may determine the mechanical load on the rotor 202 based on the magnitude of the voltage detected by the voltage detection circuit 105, in addition to or instead of the magnitude of the voltage detected by the voltage detection circuit 105, based on the timing at which the voltage detection circuit 105 detects a voltage value exceeding a predetermined voltage value. For example, the determination circuit 104 may determine the mechanical load on the rotor 202 based on whether the generation timing of the voltage value detected by the voltage detection circuit 105 is within a predetermined period determined in advance.

[0074] From time t15 to time t16, the stepping motor control device 100 applies a positive pulse to the first terminal OUT1. When the positive pulse continues to be applied to the first terminal OUT1, the rotor 202 stops at the position rotated by 135 degrees. When the stepping motor control device 100 stops applying the pulse at time t16, the rotor 202 is pulled to the 180-degree position and stops. The pulse applied from time t15 to time t16 is a drive pulse because it is a pulse for rotating the rotor 202 by approximately 180 degrees. The drive pulse is output by the control circuit 103. That is, after outputting the oscillation pulse, the control circuit 103 outputs the drive pulse after a predetermined period has elapsed.

[0075] Note that the time during which the drive pulse is applied (the pulse width of the drive pulse) only needs to be a time sufficient for the rotor 202 to rotate 180 degrees, and it is not necessary for the pulse to be applied until the rotor 202 stops at the 135-degree rotation position. Note that the time during which the drive pulse is applied may be determined according to the mechanical load determined by the determination circuit 104. In that case, the control circuit 103 controls the output time of the drive pulse according to the mechanical load determined by the determination circuit 104.

[0076] From time t21 to time t22, the stepping motor control device 100 applies a positive pulse, i.e., a rocking pulse, to the first terminal OUT1. When the positive pulse continues to be applied to the first terminal OUT1, the rotor 202 stops at the position where it has rotated 135 degrees. When the stepping motor control device 100 stops applying the pulse at time t22, the rotor 202 is pulled back to the 180-degree position and stops. Here, when the rotor 202 returns from the 135-degree position to the 180-degree position, it vibrates, and when the vibration decays, it stops at the 180-degree position.

[0077] From time t22 to time t25, the stepping motor control device 100 determines the mechanical load received by the rotor 202 due to the application of the rocking pulse. Specifically, based on the voltage detected by the voltage detection circuit 105, the determination circuit 104 determines the mechanical load received by the rotor 202.

[0078] From time t25 to time t26, the stepping motor control device 100 applies a positive pulse, i.e., a driving pulse, to the second terminal OUT2. When the positive pulse continues to be applied to the second terminal OUT2, the rotor 202 stops at the position where it has rotated 315 degrees. When the stepping motor control device 100 stops applying the pulse at time t26, the rotor 202 is pulled to the 0-degree position and stops.

[0079] FIG. 9 is a diagram showing an example of the vibration when the load teeth are meshed with the kana and the vibration when the standard teeth are meshed with the kana in the first embodiment. With reference to this figure, the vibration when the load teeth are meshed with the kana and the vibration when the standard teeth are meshed with the kana will be described. The upper part of the figure shows an example of the case where a standard tooth meshes with a kana, and the lower part of the figure shows an example of the case where a loaded tooth meshes with a kana. Specifically, an example of the case where the fourth gear 53b having the loaded tooth 62 meshes with the fourth intermediate kana 52b will be described. In the description in the same figure, the fourth gear 53b may be simply described as a gear (or the second gear), and the fourth intermediate kana 52b may be simply described as a kana (or the first gear). The first gear is a gear that rotates based on the rotation of the rotor 202, and the second gear is a gear having a loaded tooth. The left side of the figure shows a diagram of the meshing state of the gear and the kana. The right side of the figure shows a diagram of the timing at which the rocking pulse is applied and the timing at which the induced voltage is generated.

[0080] First, an example of the case where the standard tooth 60 in the upper part meshes with the kana will be described. As shown in the figure on the upper left side, when the rotor 202 that drives the kana by applying a rocking pulse vibrates, the kana vibrates due to the vibration of the rotor 202. The range in which the rotor 202 can vibrate varies depending on the magnitude of the backlash between the gear and the kana. In the state where the standard tooth 60 meshes with the kana, since the backlash is large, the range in which the rotor 202 can vibrate is also wide. As shown in the figure on the upper right side, from time t31 to time t32, a rocking pulse is applied. Based on the applied rocking pulse, the rotor 202 vibrates, and from time t33 to time t35, an induced voltage is generated. In the state where the standard tooth 60 meshes with the kana, since the range in which the rotor 202 can vibrate is wide, the generated induced voltage also becomes large. In the example shown in the same figure, at time t34, the voltage v1 is generated. The determination circuit 104 determines whether the kana (the first gear) is in contact with the loaded tooth of the gear (the second gear) as a mechanical load.

[0081] Next, an example of the case where the lower load tooth 62 and the kana are meshed will be described. As shown in the figure on the lower left side, when the rotor 202 that drives the kana by applying a rocking pulse vibrates, the kana vibrates due to the vibration of the rotor 202. However, in the state where the load tooth 62 and the kana are meshed, since the backlash is small, the range in which the rotor 202 can vibrate is also narrow. As shown in the figure on the lower right side, from time t41 to time t42, a rocking pulse is applied. Based on the applied rocking pulse, the rotor 202 vibrates, and from time t43 to time t45, an induced voltage is generated. However, in the state where the load tooth 62 and the kana are meshed, since the range in which the rotor 202 can vibrate is narrow, the generated induced voltage also becomes small. In the example shown in the figure, at time t44, the voltage v2 is generated. The voltage v2 is smaller compared to the voltage v1.

[0082] Note that when the kana is meshed between the load tooth 62 and the first standard tooth 61A, the vibration becomes small, while when the kana is meshed between the load tooth 62 and the second standard tooth 61B, the vibration becomes large. The position of the pointer may be detected by comparing these two vibrations with the vibration when the standard tooth 60 and the kana are meshed.

[0083] FIG. 10 is a flowchart showing an example of the operation of the stepping motor control device 100 in the first embodiment. A series of operations of the stepping motor control device 100 will be described with reference to this figure.

[0084] (Step S110) The control circuit 103 outputs a rocking pulse to the motor drive circuit 106. The motor drive circuit 106 drives the stepping motor 107 based on the acquired rocking pulse.

[0085] (Step S120) The voltage detection circuit 105 detects the induced voltage caused by the vibration of the rotor 202. The determination circuit 104 determines the mechanical load of the rotor 202 based on the detected value of the induced voltage or the timing at which the induced voltage is detected.

[0086] (Step S130) When a predetermined time has elapsed since the oscillation pulse was output (Step S130; YES), the control circuit 103 advances the process to Step S140. When the predetermined time has not elapsed since the oscillation pulse was output (Step S130; NO), the voltage detection circuit 105 repeats Step S120.

[0087] (Step S140) The control circuit 103 outputs a drive pulse to the motor drive circuit 106. The magnitude (voltage and time) of the drive pulse may be a predetermined value determined in advance, or may be a value based on the mechanical load of the rotor 202 determined in Step S120.

[0088] [Second Embodiment] FIG. 11 is a plan view of the front side of the movement in the second embodiment. The second embodiment will be described with reference to this figure. The clock 1-2 according to the second embodiment is different in that it includes a second motor 20B-2 instead of the second motor 20B in the first embodiment. The second motor 20B is a single-coil motor, while the second motor 20B-2 is a two-coil motor. That is, the second embodiment is an example of the case where the clock 1-2 includes a two-coil motor. For configurations similar to those of the first embodiment, the description may be omitted by assigning the same reference numerals as those in the first embodiment.

[0089] FIG. 12 is a diagram showing an example of the configuration of the pointer drive unit 110A in the second embodiment. The stepping motor 107A is an example of the second motor 20B-2. That is, the stepping motor 107A is a two-coil motor. The stepping motor 107A includes a stator 120 having a rotor accommodation hole 125, and a rotor 130 that has magnetic polarity by being magnetized in two poles in the radial direction and is rotatably disposed in the rotor accommodation hole 125. The stepping motor 107A operates for each unit step to rotate the pointer.

[0090] The stator 120 includes a stator body 121, a first core (first end) 140A magnetically joined to the stator body 121, a second core (second end) 140B, a first coil 150A wound around the first core 140A, and a second coil 150B wound around the second core 140B.

[0091] The stator body 121 is formed of a plate material using a high-permeability material such as permalloy. The stator body 121 has a T-shaped first yoke 122, a pair of second yokes 123 and 124, and is formed in an H shape in plan view. That is, the T-shaped first yoke 122 includes a straight portion 122a extending in a predetermined first direction, and a pair of projecting portions 122b and 122c projecting from one end of the straight portion 122a to both sides in a second direction orthogonal to the first direction. The second yoke 123 is provided so as to project from the other end of the straight portion 122a to the same side as the projecting portion 122b, and the second yoke 124 is provided so as to project from the other end of the straight portion 122a to the same side as the projecting portion 122c. With such a configuration of the first yoke 122, the second yoke 123, and the second yoke 124, the stator body 121 is formed in an H shape in plan view. Note that the first yoke 122, the second yoke 123, and the second yoke 124 are integrally formed.

[0092] At the intersections of the first yoke 122, the second yoke 123, and the second yoke 124 of the stator body 121, the above-described circular rotor accommodation hole 125 is formed. On the inner peripheral surface of the rotor accommodation hole 125, a pair of notches 125a are formed so as to be arranged in the second direction and face each other. The notches 125a are notched in an arc shape. These notches 125a are configured as positioning portions for determining the stop position of the rotor 130. The rotor 130 has the lowest potential energy and stably stops when its magnetic pole axis is at a position orthogonal to the line segment connecting the pair of notches 125a, that is, when the magnetic pole axis is along the first direction. Hereinafter, the stop position of the rotor 130 (the position shown in FIG. 12) when the magnetic pole axis of the rotor 130 is along the first direction and the N pole of the rotor 130 faces the first yoke 122 side is referred to as the first stop position. Also, the stop position of the rotor 130 when the magnetic pole axis of the rotor 130 is along the first direction and the S pole of the rotor 130 faces the first yoke 122 side is referred to as the second stop position.

[0093] Further, around the rotor accommodation hole 125 in the stator body 121, notches 126 are formed at three locations, which are cut out from the outer peripheral edge of the stator body 121 in a plan view toward the rotor accommodation hole 125. Each notch 126 is formed at the corner where the first yoke 122 and the second yoke 123 are connected, the corner where the first yoke 122 and the second yoke 124 are connected, and the portion where the second yoke 123 and the second yoke 124 are connected. Each notch 126 is notched in an arc shape.

[0094] Around the rotor housing hole 125 in the stator body 121, it is locally narrowed by each notch 126 (hereinafter, the locally narrowed part may be referred to as a narrow part). The narrow part is more likely to be magnetically saturated compared to other parts of the stator body 121. Due to the magnetic saturation of the narrow part, the stator body 121 is magnetically divided into three parts around the rotor housing hole 125. The stator body 121 has a first magnetic pole portion 120A disposed at a position corresponding to the second yoke 123 around the rotor 130, a second magnetic pole portion 120B disposed at a position corresponding to the second yoke 124 around the rotor 130, and a third magnetic pole portion 120C disposed at a position corresponding to the straight portion 122a of the first yoke 122 around the rotor 130.

[0095] Here, each part of the rotor 130 is divided into symbols 130A to 130D by the magnetic pole axis A and the straight line B perpendicular thereto. Among the first magnetic pole portions 120A, the portion along the rotor housing hole 125 from the notch 126 formed at the connecting portion of the second yoke 123 and the second yoke 124 to the notch 125a formed in the second yoke 123 is disposed opposite to the portion indicated by the symbol 130A of the rotor 130 located at the first stop position (the portion indicated by the symbol 130C of the rotor 130 located at the second stop position). Among the second magnetic pole portions 120B, the portion along the rotor housing hole 125 from the notch 126 formed at the connecting portion of the second yoke 123 and the second yoke 124 to the notch 125a formed in the second yoke 124 is disposed opposite to the portion indicated by the symbol 130B of the rotor 130 located at the first stop position (the portion indicated by the symbol 130D of the rotor 130 located at the second stop position). The third magnetic pole portion 120C is disposed opposite to the N pole of the rotor 130 located at the first stop position (the S pole of the rotor 130 located at the second stop position).

[0096] Each of the first core 140A and the second core 140B is formed of a high magnetic permeability material such as permalloy. The first core 140A is magnetically connected to the tip of the overhanging portion 122c and the tip of the second yoke 124. The second core 140B is magnetically connected to the tip of the overhanging portion 122b and the tip of the second yoke 123. Both ends of each of the first core 140A and the second core 140B are connected to the stator body 121 by, for example, screwing.

[0097] The first coil 150A is wound around the first core 140A and is magnetically coupled to the second magnetic pole portion 120B and the third magnetic pole portion 120C. The first coil 150A has a first terminal 150Aa and a second terminal 150Ab. The first coil 150A is wound such that when a current flows from the first terminal 150Aa to the second terminal 150Ab, a magnetic field is generated in the first coil 150A from the side of the overhanging portion 122c toward the side of the second yoke 124.

[0098] The second coil 150B is wound around the second core 140B and is magnetically coupled to the first magnetic pole portion 120A and the third magnetic pole portion 120C. The second coil 150B has a first terminal 150Ba and a second terminal 150Bb. The second coil 150B is wound such that when a current flows from the first terminal 150Ba to the second terminal 150Bb, a magnetic field is generated in the second coil 150B from the side of the second yoke 123 toward the side of the overhanging portion 122b.

[0099] The wire diameter of the conductor of the first coil 150A is the same as the wire diameter of the conductor of the second coil 150B. Also, the number of turns of the winding of the first coil 150A is the same as the number of turns of the winding of the second coil 150B. The terminals of the first coil 150A and the second coil 150B are connected to the stepping motor control device 100. In the following description, the potential of the first terminal 150Aa of the first coil 150A is set as out1, the potential of the second terminal 150Ab of the first coil 150A is set as out2, the potential of the first terminal 150Ba of the second coil 150B is set as out3, and the potential of the second terminal 150Bb of the second coil 150B is set as out4.

[0100] When magnetic flux is generated from the first coil 150A or the second coil 150B, the magnetic flux flows along each of the magnetic cores of the first magnetic core 140A and the second magnetic core 140B and the stator body 121 in the stator 120 configured as described above. Then, according to the energization state of the first coil 150A or the second coil 150B, the polarities of the first magnetic pole portion 120A, the second magnetic pole portion 120B, and the third magnetic pole portion 120C described above are switched.

[0101] That is, the stepping motor 107A includes a rotor 130, a stator 120, a first coil 150A, and a second coil 150B. The stator 120 provides magnetic flux that generates a rotational force with respect to the rotor 130. The rotor 130 is magnetized with at least two poles of an N pole and an S pole and rotates the pointer. The first coil 150A supplies magnetic flux to the first magnetic core 140A at both ends of the stator 120. The second coil 150B supplies magnetic flux to the second magnetic core 140B at both ends of the stator 120. The drive pulse output by the control circuit 103 drives the rotor 130 by a reference rotation angle corresponding to the number of poles by exciting the first coil 150A and the second coil 150B.

[0102] Note that the reference rotation angle corresponding to the number of poles here may be an angle obtained by dividing the angle of one rotation of the rotor 130 by the number of poles with which the rotor is magnetized. For example, when the rotor 130 is illustrated as having two poles, the reference rotation angle corresponding to the number of poles is an angle (180°) obtained by dividing the angle of one rotation by 2. Also, when the rotor 130 is illustrated as having four poles, the reference rotation angle corresponding to the number of poles is an angle (90°) obtained by dividing the angle of one rotation by 4.

[0103] FIG. 13 is a diagram showing an example of a rocking pulse and a drive pulse in the second embodiment. In the description of this figure, the horizontal axis represents time, "Out1" represents the magnitude of the voltage applied to the first terminal OUT1 at each time, "Out2" represents the magnitude of the voltage applied to the second terminal OUT2 at each time, "Out3" represents the magnitude of the voltage applied to the third terminal OUT3 at each time, and "Out4" represents the magnitude of the voltage applied to the fourth terminal OUT4 at each time. Also, with the second stop position described with reference to FIG. 12 set to 0 degrees for the position of the rotor at each time, the rotational position of the rotor 202 will be described. The control from time t51 to time t61 is control to rotate the rotor 202 counterclockwise from 0 degrees to 180 degrees, and the control from time t61 to time t69 is control to rotate the rotor 202 counterclockwise from 180 degrees to 0 degrees.

[0104] From time t51 to time t52, the stepping motor control device 100 applies a positive-direction pulse to the fourth terminal OUT4. When the positive-direction pulse continues to be applied to the fourth terminal OUT4, the rotor 130 stops at the position rotated by 45 degrees. When the stepping motor control device 100 stops applying the pulse at time t52, the rotor 130 is pulled back to the 0-degree position and stops. Here, when the rotor 130 returns from the 45-degree position to the 0-degree position, due to inertia, it rotates at least once counterclockwise to a position with a negative rotation angle and rotates clockwise to a position with a positive rotation angle repeatedly. That is, the rotor 130 vibrates and stops at the 0-degree position as the vibration decays.

[0105] From time t52 to time t55, the stepping motor control device 100 determines the mechanical load received by the rotor 130 by applying a rocking pulse. Specifically, based on the voltage detected by the voltage detection circuit 105, the determination circuit 104 determines the mechanical load received by the rotor 130.

[0106] From time t55 to time t57, the stepping motor control device 100 applies drive pulses. The positive pulse applied to the fourth terminal OUT4 from time t55 to time t56 is referred to as the first drive pulse. The positive pulse applied to the second terminal OUT2 from time t56 to time t57 is referred to as the second drive pulse. When a positive pulse continues to be applied to the second terminal OUT2, the rotor 130 stops at the position rotated by 135 degrees. When the stepping motor control device 100 stops applying the pulse at time t57, the rotor 130 is pulled to the 180-degree position and stops.

[0107] From time t61 to time t62, the stepping motor control device 100 applies a positive pulse, that is, a rocking pulse, to the third terminal OUT3. When a positive pulse continues to be applied to the third terminal OUT3, the rotor 130 stops at the position rotated by 225 degrees. When the stepping motor control device 100 stops applying the pulse at time t62, the rotor 130 is pulled back to the 180-degree position and stops. Here, when the rotor 130 returns from the 225-degree position to the 180-degree position, it vibrates, and when the vibration decays, it stops at the 180-degree position.

[0108] From time t62 to time t65, the stepping motor control device 100 determines the mechanical load received by the rotor 130 due to the application of the rocking pulse. Specifically, based on the voltage detected by the voltage detection circuit 105, the determination circuit 104 determines the mechanical load received by the rotor 130.

[0109] From time t65 to time t67, the stepping motor control device 100 applies drive pulses. Specifically, from time t65 to time t66, the stepping motor control device 100 applies a positive-direction pulse to the third terminal OUT3 as the first drive pulse, and from time t66 to time t67, it applies a positive-direction pulse to the first terminal OUT1 as the second drive pulse. When a positive-direction pulse continues to be applied to the first terminal OUT1, the rotor 130 stops at the position where it has rotated 315 degrees. When the stepping motor control device 100 stops applying the pulse at time t66, the rotor 130 is pulled to the 0-degree position and stops.

[0110] FIG. 14 is a diagram showing a modified example of the swing pulse and the drive pulse in the second embodiment. In the modified example shown in this figure, it is different from the example described in FIG. 13 in that it includes a swing pulse (first swing pulse) that rotates a predetermined angle in the forward rotation direction from the stationary position and a swing pulse (second swing pulse) that rotates a predetermined angle in the reverse rotation direction from the stationary position. In the description of this figure, the horizontal axis represents time, "Out1" represents the magnitude of the voltage applied to the first terminal OUT1 at each time, "Out2" represents the magnitude of the voltage applied to the second terminal OUT2 at each time, "Out3" represents the magnitude of the voltage applied to the third terminal OUT3 at each time, and "Out4" represents the magnitude of the voltage applied to the fourth terminal OUT4 at each time. Also, with the second stop position described with reference to FIG. 12 as 0 degrees for the position of the rotor at each time, the rotational position of the rotor 202 will be described. The control from time t51 to time t61 is control to rotate the rotor 202 counterclockwise from 0 degrees to 180 degrees, and the control from time t61 to time t69 is control to rotate the rotor 202 counterclockwise from 180 degrees to 0 degrees.

[0111] From time t71 to time t74, the stepping motor control device 100 applies a rocking pulse. Specifically, from time t71 to time t72, the stepping motor control device 100 applies a positive pulse (the first rocking pulse) to the fourth terminal OUT4. When a positive pulse is applied to the fourth terminal OUT4, the rotor 130 starts to rotate toward the 45-degree position. When the stepping motor control device 100 stops applying the pulse at time t72, the rotor 130 starts to rotate toward the 0-degree position. Next, the stepping motor control device 100 applies a positive pulse (the second rocking pulse) to the first terminal OUT1. When a positive pulse is applied to the first terminal OUT1, the rotor 130 starts to rotate toward the 315-degree position. Here, since the rotor 130 is pulled to the 315-degree position after being pulled to the 45-degree position once, it vibrates greatly due to inertia. The rotor 130 comes to rest at the 0-degree position as the vibration decays.

[0112] From time t74 to time t75, the stepping motor control device 100 determines the mechanical load received by the rotor 130 due to the application of the rocking pulse. Specifically, based on the voltage detected by the voltage detection circuit 105, the determination circuit 104 determines the mechanical load received by the rotor 130.

[0113] The control from time t75 to time t81 is the same as the control from time t55 to time t61 described in FIG. 13, and thus the description thereof is omitted.

[0114] From time t81 to time t84, the stepping motor control device 100 applies a rocking pulse. Specifically, from time t81 to time t82, the stepping motor control device 100 applies a positive pulse (first rocking pulse) to the third terminal OUT3. When a positive pulse is applied to the third terminal OUT3, the rotor 130 starts to rotate toward the 225-degree position. When the stepping motor control device 100 stops applying the pulse at time t82, the rotor 130 starts to rotate toward the 180-degree position. Next, the stepping motor control device 100 applies a positive pulse (second rocking pulse) to the second terminal OUT2. When a positive pulse is applied to the second terminal OUT2, the rotor 130 starts to rotate toward the 135-degree position. Here, since the rotor 130 is pulled to the 135-degree position after being pulled to the 225-degree position once, it vibrates greatly due to inertia. The rotor 130 stops at the 180-degree position as the vibration decays.

[0115] From time t84 to time t85, the stepping motor control device 100 determines the mechanical load received by the rotor 130 due to the application of the rocking pulse. Specifically, based on the voltage detected by the voltage detection circuit 105, the determination circuit 104 determines the mechanical load received by the rotor 130.

[0116] The control from time t85 to time t89 is the same as the control from time t65 to time t69 described in FIG. 13, and thus the description is omitted.

[0117] In addition, in one example shown in the above-described modification, the control circuit 103 outputs a first rocking pulse that rocks the rotor 130 by outputting a pulse of energy that rotates the rotor 130 in the forward rotation direction, and a pulse of energy that rotates the rotor 130 in the direction opposite to the forward rotation direction after outputting the first rocking pulse. By outputting both the second rocking pulses that rock the rotor 130, the rotor 130 can be vibrated greatly. The control circuit 103 may output only the first rocking pulse as a rocking pulse as in an example of the second embodiment, or may output the first rocking pulse and the second rocking pulse as rocking pulses as in a modification of the second embodiment.

[0118] When outputting both the first rocking pulse and the second rocking pulse, while the rotor 130 can be vibrated greatly, the time required for detection may become long. Therefore, when outputting a rocking pulse according to a predetermined period in which a drive pulse is output, it may be configured to output only the first rocking pulse. Further, when outputting a rocking pulse at a predetermined timing not according to a predetermined period in which a drive pulse is output, it may be configured to output both the first rocking pulse and the second rocking pulse.

[0119] Note that the control unit 103 may be configured to have a rocking pulse output mode for outputting a rocking pulse and a rocking pulse non-output mode for not outputting a rocking pulse.

[0120] [Summary of Effects of Embodiment] According to the above-described embodiment, the stepping motor control device 100 includes a control circuit 103 that outputs a drive pulse and a rocking pulse, a voltage detection circuit 105 that detects the vibration of the rotor, and a determination circuit 104 that determines the mechanical load received by the rotor based on the detected voltage. Thus, the vibration of the rotor when the rocking pulse is output is detected. Therefore, according to the present embodiment, even when the vibration of the rotor is small by the motor, the rotor can be vibrated, an induced voltage is generated, so that the rotation state of the rotor can be detected, and the mechanical load of the rotor can be determined.

[0121] Conventionally, in the case of a motor configuration with two coils, the induced voltage is dispersed in the two coils, and the effect of the electromagnetic brake by the coils is enhanced. Therefore, the vibration of the rotor during normal driving has been reduced. However, according to the present embodiment, since a rocking pulse for vibrating the rotor is applied, the rotation state of the rotor can be surely detected, and the mechanical load of the rotor can be determined. In addition, depending on the motor, the inertia of the rotor may be small, or the magnetic holding force of the stator may be small. In such a case, the vibration of the rotor during normal driving is reduced, and it has been difficult to detect the rotation state of the rotor. However, according to the present embodiment, since a rocking pulse for vibrating the rotor is applied, the detection of the rotation state of the rotor can be ensured, and the mechanical load of the rotor can be determined.

[0122] Note that the mechanical load determined by the stepping motor control device 100 is not limited to an example in the case where the gear has load teeth, but widely includes loads that occur when rotating a daily rotation gear.

[0123] According to the above-described embodiment, after outputting the rocking pulse, the control circuit 103 outputs a drive pulse after a predetermined period has elapsed. Therefore, since the control circuit 103 outputs a drive pulse after the vibration of the rotor due to the rocking pulse has sufficiently decayed, it is possible to suppress out-of-step caused by the vibration due to the rocking pulse. Note that the predetermined period from the output of the rocking pulse to the output of the drive pulse is a time sufficient for the vibration of the rotor due to the rocking pulse to decay, and may be determined based on the inertia of the rotor.

[0124] According to the above-described embodiment, the stepping motor control device 100 detects a state in which the kana and the load teeth are engaged as a mechanical load. Therefore, according to the present embodiment, the reference pointer position can be specified.

[0125] According to the above-described embodiments, the control circuit 103 controls the output time of the drive pulse according to the mechanical load determined by the determination circuit 104. Therefore, when the mechanical load increases, it is possible to prevent the stepping motor from losing synchronization by increasing the time for applying the drive pulse (i.e., applying a large amount of energy). For example, when driving a calendar, since the load increases, it is preferable to rotate the rotor with a larger amount of energy than usual. According to the present embodiment, even in such a case, the energy to be applied can be varied according to the load.

[0126] According to the above-described embodiments, the stepping motor control device 100 includes a first swing pulse and a second swing pulse. Here, when driving the stepping motor, depending on the driving speed and the magnitude of the load to be connected, there are cases where it is preferable to apply only the first swing pulse and cases where it is preferable to apply the first swing pulse and the second swing pulse. According to the present embodiment, a suitable swing pulse can be applied according to the driving speed of the stepping motor and the magnitude of the load to be connected.

[0127] According to the above-described embodiments, the stepping motor control device 100 can prevent misdetection of the mechanical load by applying the first swing pulse and the second swing pulse in the case of normal hand movement. Further, when the pointer is driven at high speed or the like, the stepping motor control device 100 can shorten the detection time and drive the pointer at high speed by applying only the first swing pulse.

[0128] According to the above-described embodiments, the determination circuit 104 determines the mechanical load based on whether or not the value of the voltage detected by the voltage detection circuit 105 exceeds a threshold value. Therefore, according to the present embodiment, the mechanical load of the rotor can be easily detected.

[0129] According to the above-described embodiment, the determination circuit 104 determines whether or not an induced voltage is generated at the timing when an induced voltage will be generated due to the vibration of the rotor after the rocking pulse is applied. Therefore, according to the present embodiment, it is possible to suppress false detection that may occur when the load temporarily increases due to an external load.

[0130] According to the above-described embodiment, the stepping motor control device 100 includes a mode for outputting a rocking pulse and a mode for not outputting a rocking pulse. Therefore, according to the present embodiment, when the rocking pulse is unnecessary, the power consumption can be reduced by not outputting the rocking pulse.

[0131] [Third Embodiment] Next, a third embodiment will be described with reference to FIGS. 15 to 18. In the above-described embodiment, an example of the case where the energy of the drive pulse is changed by the stepping motor control device 100 has been described. Specifically, an example of the case where the control circuit 103 controls the energy of the drive pulse by controlling the output time of the drive pulse according to the mechanical load determined by the determination circuit 104 has been described. In the third embodiment, a specific example of the case where the energy for driving the stepping motor 107 is controlled by various methods will be described.

[0132] In an example described with reference to FIGS. 15 to 18, an example of the case where the stepping motor is a two-coil motor will be described. However, the third embodiment is not limited to an example of a two-coil motor. Even when the clock 1 includes a single-coil motor instead of a two-coil motor, the same processing as the processing described below can be applied.

[0133] FIG. 15 is a diagram showing an example of controlling the energy for driving a stepping motor by controlling the output time of a drive pulse in the third embodiment. With reference to this figure, an example of controlling the energy for driving a stepping motor by controlling the output time of a drive pulse will be described. FIG. 15(A) shows an example when the induced voltage can be detected, and FIG. 15(B) shows an example when the induced voltage cannot be detected.

[0134] In the description of FIG. 15, the horizontal axis indicates time, “Out1” indicates the magnitude of the voltage applied to the first terminal OUT1 at each time, “Out2” indicates the magnitude of the voltage applied to the second terminal OUT2 at each time, “Out3” indicates the magnitude of the voltage applied to the third terminal OUT3 at each time, and “Out4” indicates the magnitude of the voltage applied to the fourth terminal OUT4 at each time.

[0135] First, with reference to FIG. 15(A), an example when the induced voltage can be detected will be described. At time t111, the stepping motor control device 100 applies a swing pulse to the stepping motor 107 by controlling “Out4”. The stepping motor control device 100 determines the mechanical load received by the rotor 130 due to the application of the swing pulse. The voltage detection circuit 105 detects the induced voltage generated in “Out4”. The determination circuit 104 determines the mechanical load received by the rotor 130 based on the voltage detected by the voltage detection circuit 105. Specifically, since the induced voltage is equal to or higher than a predetermined threshold value TH, the determination circuit 104 determines that the induced voltage has been detected normally.

[0136] Next, with reference to FIG. 15(B), an example when the induced voltage cannot be detected will be described. At time t121, the stepping motor control device 100 applies a swing pulse to the stepping motor 107 by controlling "Out4". The stepping motor control device 100 determines the mechanical load received by the rotor 130 due to the application of the swing pulse. The voltage detection circuit 105 detects the induced voltage generated in "Out4". The determination circuit 104 determines that the induced voltage could not be detected normally because the induced voltage is equal to or less than a predetermined threshold value TH. In this case, the control circuit 103 controls the energy for driving the stepping motor 107 by controlling the output time of the drive pulse. Specifically, the control circuit 103 controls the output time of the drive pulse applied to "Out1" at time 125 and the output time of the drive pulse applied to "Out3" at time 127 to be longer, so as to control the energy for driving the stepping motor 107 to increase.

[0137] FIG. 16 is a diagram showing an example of a case where the energy for driving a stepping motor is controlled by controlling the excitation method of the stepping motor in the third embodiment. With reference to this figure, an example of a case where the energy for driving a stepping motor is controlled by controlling the excitation method of the stepping motor will be described. FIG. 16(A) shows an example of a case where the induced voltage could be detected, and FIG. 16(B) shows an example of a case where the induced voltage could not be detected.

[0138] In the description of FIG. 16, the horizontal axis represents time, "Out1" represents the magnitude of the voltage applied to the first terminal OUT1 at each time, "Out2" represents the magnitude of the voltage applied to the second terminal OUT2 at each time, "Out3" represents the magnitude of the voltage applied to the third terminal OUT3 at each time, and "Out4" represents the magnitude of the voltage applied to the fourth terminal OUT4 at each time.

[0139] Next, with reference to FIG. 16(A), an example of a case where the induced voltage could be detected will be described. At time t211, the stepping motor control device 100 applies a rocking pulse to the stepping motor 107 by controlling "Out4". The stepping motor control device 100 determines the mechanical load received by the rotor 130 due to the application of the rocking pulse. The voltage detection circuit 105 detects the induced voltage generated in "Out4". The determination circuit 104 determines the mechanical load received by the rotor 130 based on the voltage detected by the voltage detection circuit 105. Specifically, since the induced voltage is equal to or higher than a predetermined threshold value TH, the determination circuit 104 determines that the induced voltage has been detected normally. In an example shown in FIG. 16(A), the control circuit 103 controls the stepping motor 107 by single-phase excitation.

[0140] Next, an example in the case where the induced voltage cannot be detected will be described with reference to FIG. 16(B). At time t221, the stepping motor control device 100 applies a rocking pulse to the stepping motor 107 by controlling "Out4". The stepping motor control device 100 determines the mechanical load received by the rotor 130 due to the application of the rocking pulse. The voltage detection circuit 105 detects the induced voltage generated in "Out4". Since the induced voltage is equal to or lower than a predetermined threshold value TH, the determination circuit 104 determines that the induced voltage cannot be detected normally. In this case, the control circuit 103 controls the energy for driving the stepping motor 107 by controlling the excitation method of the stepping motor 107. Specifically, the control circuit 103 controls the energy for driving the stepping motor 107 by controlling the excitation method of the stepping motor 107 from single-phase excitation to two-phase excitation. More specifically, the control circuit 103 applies "Out1" and "Out3" at time 225 and applies only "Out3" at time 227 to perform two-phase excitation drive, and controls so that the energy for driving the stepping motor 107 increases.

[0141] FIG. 17 is a diagram showing an example of controlling the energy for driving a stepping motor by controlling the duty ratio of a drive pulse in the third embodiment. With reference to this figure, an example of controlling the energy for driving a stepping motor by controlling the duty ratio of a drive pulse will be described. FIG. 17(A) shows an example when the induced voltage can be detected, and FIG. 17(B) shows an example when the induced voltage cannot be detected. In the example shown in this figure, the control circuit 103 controls the stepping motor 107 by applying a PWM signal as a drive pulse.

[0142] In the description of FIG. 17, the horizontal axis represents time, "Out1" represents the magnitude of the voltage applied to the first terminal OUT1 at each time, "Out2" represents the magnitude of the voltage applied to the second terminal OUT2 at each time, "Out3" represents the magnitude of the voltage applied to the third terminal OUT3 at each time, and "Out4" represents the magnitude of the voltage applied to the fourth terminal OUT4 at each time.

[0143] Next, with reference to FIG. 17(A), an example when the induced voltage can be detected will be described. At time t311, the stepping motor control device 100 applies a rocking pulse to the stepping motor 107 by controlling "Out4". The stepping motor control device 100 determines the mechanical load received by the rotor 130 due to the application of the rocking pulse. The voltage detection circuit 105 detects the induced voltage generated in "Out4". The determination circuit 104 determines the mechanical load received by the rotor 130 based on the voltage detected by the voltage detection circuit 105. Specifically, since the induced voltage is equal to or higher than a predetermined threshold TH, the determination circuit 104 determines that the induced voltage has been detected normally. In the example shown in FIG. 17(A), the control circuit 103 controls the stepping motor 107 by applying a PWM signal as a drive pulse at times 315 and 317.

[0144] Next, with reference to FIG. 17(B), an example of the case where the induced voltage cannot be detected will be described. At time t321, the stepping motor control device 100 applies a swing pulse to the stepping motor 107 by controlling "Out4". The stepping motor control device 100 determines the mechanical load received by the rotor 130 due to the application of the swing pulse. The voltage detection circuit 105 detects the induced voltage generated in "Out4". Since the induced voltage is equal to or less than a predetermined threshold value TH, the determination circuit 104 determines that the induced voltage could not be detected normally. In this case, the control circuit 103 controls the energy for driving the stepping motor 107 by controlling the duty ratio of the drive pulse. Specifically, the control circuit 103 controls the energy for driving the stepping motor 107 to increase by making the duty ratio of the drive pulse applied at times 325 and 327 larger than the duty ratio of the drive pulse applied at times 315 and 317.

[0145] FIG. 18 is a diagram showing an example of the case where the energy for driving a stepping motor is controlled by controlling the voltage of the drive pulse in the third embodiment. With reference to this figure, an example of the case where the energy for driving a stepping motor is controlled by controlling the duty ratio of the drive pulse will be described. FIG. 18(A) shows an example of the case where the induced voltage could be detected, and FIG. 18(B) shows an example of the case where the induced voltage could not be detected. Note that in the present embodiment, the motor drive circuit 106 includes a voltage converter such as a DC / DC converter or an LDO (Low Dropout) not shown in the figure, and has a configuration in which the voltage applied to the stepping motor 107 can be selected.

[0146] In the description of FIG. 18, the horizontal axis indicates time, "Out1" indicates the magnitude of the voltage applied to the first terminal OUT1 at each time, "Out2" indicates the magnitude of the voltage applied to the second terminal OUT2 at each time, "Out3" indicates the magnitude of the voltage applied to the third terminal OUT3 at each time, and "Out4" indicates the magnitude of the voltage applied to the fourth terminal OUT4 at each time.

[0147] Next, with reference to FIG. 18(A), an example of the case where the induced voltage can be detected will be described. At time t411, the stepping motor control device 100 applies a swing pulse to the stepping motor 107 by controlling "Out4". The stepping motor control device 100 determines the mechanical load received by the rotor 130 due to the application of the swing pulse. The voltage detection circuit 105 detects the induced voltage generated in "Out4". The determination circuit 104 determines the mechanical load received by the rotor 130 based on the voltage detected by the voltage detection circuit 105. Specifically, since the induced voltage is equal to or higher than a predetermined threshold value TH, the determination circuit 104 determines that the induced voltage has been detected normally. In the example shown in FIG. 17(A), the control circuit 103 controls the stepping motor 107 by applying a voltage V1 as a drive pulse at times 415 and 417.

[0148] Next, with reference to FIG. 18(B), an example of the case where the induced voltage cannot be detected will be described. At time t421, the stepping motor control device 100 applies a rocking pulse to the stepping motor 107 by controlling "Out4". The stepping motor control device 100 determines the mechanical load received by the rotor 130 due to the application of the rocking pulse. The voltage detection circuit 105 detects the induced voltage generated in "Out4". The determination circuit 104 determines that the induced voltage could not be detected normally because the induced voltage is equal to or less than a predetermined threshold value TH. In this case, the control circuit 103 controls the energy for driving the stepping motor 107 by controlling the voltage of the drive pulse. Specifically, the control circuit 103 controls the energy for driving the stepping motor 107 to increase by setting the voltage of the drive pulse applied at times 415 and 417 to a voltage V2 greater than the voltage V1. For example, the voltage V1 may be a voltage generated by a voltage converter, and the voltage V2 may be the power supply voltage of a battery.

[0149] [Summary of Effects of the Third Embodiment] According to the above-described embodiment, the stepping motor control device 100 includes the control circuit 103, and controls the energy for driving the stepping motor 107 according to the mechanical load determined by the determination circuit 104. Therefore, according to the present embodiment, when the mechanical load increases, it is possible to prevent the stepping motor from losing synchronization by increasing the energy for driving the stepping motor 107.

[0150] Further, according to the above-described embodiment, when it is determined by the determination circuit 104 that the induced voltage could not be detected normally, the control circuit 103 controls the energy for driving the stepping motor 107 by controlling the output time of the drive pulse. Since the control circuit 103 controls the energy for driving the stepping motor 107 by controlling the output time of the drive pulse, it is possible to easily control the energy for driving the stepping motor 107 without using new hardware for varying the energy.

[0151] Also, according to the above-described embodiment, when it is determined by the determination circuit 104 that the induced voltage cannot be detected normally, the control circuit 103 controls the energization method of the stepping motor 107 to control the energy for driving the stepping motor 107. Since the control circuit 103 controls the energy for driving the stepping motor 107 by controlling the energization method of the stepping motor 107, it is possible to easily control the energy for driving the stepping motor 107 without using new hardware for varying the energy. Further, the control circuit 103 can surely control the energy for driving the stepping motor 107.

[0152] Also, according to the above-described embodiment, when it is determined by the determination circuit 104 that the induced voltage cannot be detected normally, the control circuit 103 controls the energy for driving the stepping motor 107 by controlling the duty ratio of the drive pulse. Since the control circuit 103 controls the energy for driving the stepping motor 107 by controlling the duty ratio of the drive pulse, it is possible to control the energy for driving the stepping motor 107 even when the drive pulse is PWM-driven.

[0153] Also, according to the above-described embodiment, when it is determined by the determination circuit 104 that the induced voltage cannot be detected normally, the control circuit 103 controls the energy for driving the stepping motor 107 by controlling the voltage of the drive pulse. Since the control circuit 103 controls the energy for driving the stepping motor 107 by controlling the voltage of the drive pulse, it is possible to control the energy for driving the stepping motor 107 even when there is a time constraint on the time during which the drive pulse can be applied.

[0154] In this embodiment, the above-described methods can also be combined. For example, control may be performed to simultaneously change both the application time of the drive pulse and the voltage, or control may be performed to simultaneously change both the duty ratio of the PWM and the voltage. Further, when changing to two-phase excitation, control may be performed to simultaneously change at least one of the application time of the drive pulse and the voltage. By combining these, it is possible to control the energy for driving the stepping motor 107 with higher resolution.

[0155] [Fourth Embodiment] Next, the fourth embodiment will be described with reference to FIG. 19. In the above-described embodiment, a modified example of the rocking pulse was described with reference to FIG. 14. In the fourth embodiment, the modified example of the rocking pulse described with reference to FIG. 14 will be supplementarily described.

[0156] FIG. 19 is a diagram showing an example of the rocking pulse and the drive pulse in the fourth embodiment. The example described with reference to this figure is different from the example described with reference to FIG. 14 in that the rotation direction of the rocking pulse is not limited. In the example described with reference to FIG. 14, after rotating the rotor 130 in the forward rotation direction by the first rocking pulse, it was rotated in the reverse rotation direction by the second rocking pulse. However, in this embodiment, after rotating the rotor 130 in the reverse rotation direction by the first rocking pulse, it may be rotated in the reverse rotation direction by the second rocking pulse.

[0157] In this embodiment, the rocking pulse is no different from an example described with reference to FIG. 14 in that it is either the first rocking pulse or the second rocking pulse. However, in this embodiment, it is different from the example described with reference to FIG. 14 in that the rotation direction of the first rocking pulse or the second rocking pulse is not limited. That is, the first rocking pulse has energy to rotate the rotor 130 in the first rotation direction and rocks the rotor 130. The second rocking pulse is a rocking pulse applied after the first rocking pulse is output, has energy to rotate the rotor 130 in the second rotation direction, and rocks the rotor 130.

[0158] Specifically, the first rotation direction may be the normal rotation direction, and the second rotation direction may be the reverse rotation direction opposite to the first rotation direction. Also, the first rotation direction may be the reverse rotation direction, and the second rotation direction may be the normal rotation direction opposite to the first rotation direction.

[0159] [Summary of Effects of the Fourth Embodiment]

[0160] According to the above-described embodiment, the control circuit 103 applies the first rocking pulse and the second rocking pulse as drive pulses, and the rotation directions of the first rocking pulse and the second rocking pulse are arbitrary. Therefore, according to this embodiment, the rotor of the stepping motor 107 can be suitably rocked.

[0161] [Fifth Embodiment] Next, the fifth embodiment will be described. First, the problem to be solved by the fifth embodiment will be described. The rocking pulse described in the above-described embodiment needs to give energy suitable for the rotor to rock when it meshes with the normal teeth and not vibrate greatly when it meshes with the load teeth. For example, if the energy of the rocking pulse is too large, even a loaded tooth will rock, and if the energy of the rocking pulse is too small, even a normal tooth may not rock. That is, it is desired to suitably adjust the energy of the rocking pulse according to the load of the gear. In the present embodiment, the object is to suitably adjust the energy of the rocking pulse.

[0162] FIG. 20 is a diagram showing the presence or absence of detection of the induced voltage when the voltages of the driving pulse and the rocking pulse in the fifth embodiment are changed. On the left side of the figure, an example where the spring force of the loaded tooth is strong is shown as "high load". On the left side of the figure, an example where the spring force of the loaded tooth is weak is shown as "low load". For each of the cases of "high load" and "low load", an example when the applied voltage of the rocking pulse is set to "3.0 [V]" and an example when it is set to "1.8 [V]" are shown respectively. 3.0 [V] assumes the power supply voltage, and 1.8 [V] assumes the voltage generated from the power supply voltage by a DC / DC converter, an LDO, or the like.

[0163] The vertical axis in the figure indicates the magnitude of the energy of the rocking pulse, showing that the energy becomes smaller as it goes upward and larger as it goes downward. In an example shown in the figure, for example, the energy is made different by changing the time for applying the rocking pulse. Note that the energy is different between an example when it is set to "3.0 [V]" and an example when it is set to "1.8 [V]". Also, the horizontal axis in the figure indicates steps, with 1 cell indicating 1 step. In the same figure, out of the gear that makes one revolution in 360 steps, 11 steps centered on the loaded tooth are shown. The cells shaded in the figure indicate that they have been detected as loaded teeth. The cells not shaded in the figure indicate that they have been detected as normal teeth. The boundary between the shaded cells and the non-shaded cells indicates the minimum energy amount and the maximum energy amount of the rocking pulse. That is, by applying an energy amount between the minimum energy amount and the maximum energy amount as the rocking pulse, normal teeth and loaded teeth can be suitably detected.

[0164] Let's take a look at an example in the case of "high load". When the oscillating pulse is driven at 3.0 [V], the difference between the minimum energy amount and the maximum energy amount (i.e., the difference in the pulse application time) is 0.27 [ms]. When the oscillating pulse is driven at 1.8 [V], the difference between the minimum energy amount and the maximum energy amount is 0.78 [ms]. Let's take a look at an example in the case of "low load". When the oscillating pulse is driven at 3.0 [V], the difference between the minimum energy amount and the maximum energy amount is 0.18 [ms]. When the oscillating pulse is driven at 1.8 [V], the difference between the minimum energy amount and the maximum energy amount is 0.56 [ms].

[0165] In both the case of "high load" and the case of "low load", when the oscillating pulse is driven at 1.8 [V], the difference between the minimum energy amount and the maximum energy amount is larger. That is, by setting the oscillating pulse to a voltage lower than the driving pulse, the energy of the oscillating pulse can be controlled with high resolution.

[0166] In the present embodiment, in order to control the energy of the oscillating pulse with high resolution, the oscillating pulse is set to a voltage lower than the driving pulse. Specifically, when a driving pulse is output from the control circuit 103, the motor drive circuit 106 drives the stepping motor 107 with a first voltage (for example, 3.0 [V]), and when an oscillating pulse is output from the control circuit 103, the stepping motor 107 is driven with a second voltage (for example, 1.8 [V]) lower than the first voltage. The first voltage may be, for example, the power supply voltage of the battery that drives the clock 1, and the second voltage may be, for example, the voltage obtained by dropping the power supply voltage of the battery by a DC / DC converter, an LDO, or the like.

[0167] [Summary of the effects of the fifth embodiment] According to the present embodiment, by setting the oscillating pulse to a voltage lower than the driving pulse, the energy of the oscillating pulse can be controlled with high resolution. Therefore, the energy of the oscillating pulse can be suitably controlled. Thus, according to the present embodiment, the normal teeth and the load teeth can be accurately detected.

[0168] [Sixth Embodiment] Next, the sixth embodiment will be described. First, the problem to be solved by the stepping motor control device 100 according to the sixth embodiment will be described. The plurality of wheel train groups provided in the clock 1 may have a large load due to long-term use. Also, even when the usage period is short, depending on the usage situation and magnetic field environment, the overall load may become large. In the present embodiment, when the load of the wheel train provided in the clock 1 becomes large, control is performed so that the energy for driving the stepping motor 107 becomes large, thereby attempting to suppress problems such as out-of-tune.

[0169] FIG. 21 is a diagram for explaining drive pulse rank control in the sixth embodiment. While referring to this figure, a series of operations of the stepping motor control device 100 according to the sixth embodiment will be described. Note that the gears described in the present embodiment are described on the premise that they rotate one full turn in 360 [steps]. Also, the processes described in the present embodiment are started when the power is turned on, and thereafter, the control is repeated.

[0170] (Step S211) As an initial condition, the stepping motor control device 100 sets the drive rank dr to 0 and the stable count NS to 0. The drive rank dr indicates the rank of the energy for driving the stepping motor 107. The larger the drive rank dr, the larger the energy for driving the stepping motor 107. The stable count NS is a counter that is incremented for each step. The stepping motor control device 100 determines whether or not to change the drive rank dr by referring to the stable count NS.

[0171] (Step S213) After the power is turned on, the stepping motor control device 100 rotates the gear by one revolution (i.e., 360 [step]) to identify the position of the load tooth. After the stepping motor control device 100 stores the position of the load tooth, the process proceeds to step S215. (Step S215) The stepping motor control device 100 determines whether it is the stored position of the load tooth. If the stepping motor control device 100 determines that it is the stored position of the load tooth (step 215; YES), the process proceeds to step S217. If the stepping motor control device 100 determines that it is not the stored position of the load tooth (step 215; NO), the process proceeds to step S221.

[0172] (Step S217) The stepping motor control device 100 applies a swing pulse to the stepping motor 107. (Step S219) The stepping motor control device 100 applies a drive pulse to the stepping motor 107. That is, since the induced voltage cannot be obtained at the position of the load tooth, the control of the drive rank is not performed.

[0173] The stepping motor control device 100 controls the drive rank dr, which is the rank of the drive pulse, based on the result of determining the induced voltage VRs of the normal tooth by performing the processes from step S221 to step S241. (Step S221) The stepping motor control device 100 applies a swing pulse to the stepping motor 107. (Step S223) The stepping motor control device 100 determines whether the induced voltage VRs of the normal tooth is greater than a predetermined threshold value Vcomp. If the induced voltage VRs of the normal tooth is greater than the predetermined threshold value Vcomp (step 223; YES), the process proceeds to step S225. If the induced voltage VRs of the normal tooth is less than or equal to the predetermined threshold value Vcomp (step 223; NO), the process proceeds to step S235.

[0174] (Step S225) The stepping motor control device 100 determines whether the drive rank dr is 0. If the drive rank dr is 0 (Step 225; YES), the stepping motor control device 100 advances the process to Step S233. If the drive rank dr is not 0 (Step 225; NO), the stepping motor control device 100 advances the process to Step S227. (Step S227) The stepping motor control device 100 increments the stable count NS by 1. (Step S229) The stepping motor control device 100 determines whether the stable count NS is 360. If the stable count NS is 360 (Step 229; YES), the stepping motor control device 100 advances the process to Step S231. If the stable count NS is not 360 (Step 229; NO), the stepping motor control device 100 advances the process to Step S233.

[0175] (Step S231) The stepping motor control device 100 subtracts 1 from the drive rank dr. That is, the stepping motor control device 100 drives the stepping motor 107 with less energy from the next time on. The stepping motor control device 100 sets the stable count NS to 0. (Step S233) The stepping motor control device 100 maintains the drive rank dr. (Step S235) The stepping motor control device 100 adds 1 to the drive rank dr. That is, the stepping motor control device 100 drives the stepping motor 107 with greater energy from the next time on. The stepping motor control device 100 sets the stable count NS to 0. (Step S241) The stepping motor control device 100 applies a drive pulse to the stepping motor 107.

[0176] [Summary of Effects of the Sixth Embodiment] According to the above-described embodiment, the stepping motor control device 100 includes the control circuit 103, and when the induced voltage Vrs is smaller than a predetermined threshold value Vcomp, the rank of the drive pulse is increased. That is, when the mechanical load received by the rotor determined by the determination circuit 104 is smaller than a predetermined threshold value, the control circuit 103 applies a drive pulse having a rank larger than the drive pulse applied immediately before among the drive pulses of a plurality of ranks having different energies. Further, the stepping motor control device 100 includes the control circuit 103, and when the induced voltage Vrs is larger than a predetermined threshold value Vcomp, after the stable count NS has elapsed for about one rotation of the gear, the rank of the drive pulse is decreased. That is, when a result that the mechanical load received by the rotor determined by the determination circuit 104 is larger than a predetermined threshold value is continuously obtained a predetermined number of times or more, the control circuit 103 applies a drive pulse having a rank smaller than the drive pulse applied immediately before among the drive pulses of a plurality of ranks having different energies.

[0177] According to the above-described embodiment, even when the load of the gear train included in the clock 1 becomes large, it is possible to suppress problems such as out-of-tune by controlling so that the energy for driving the stepping motor 107 becomes large. Also, when reducing the energy of the drive pulse, after determining the load for one rotation of the gear, since it deflects, it is possible to prevent problems such as out-of-tune from occurring due to erroneously reducing the energy of the drive pulse.

[0178] [7th Embodiment] Next, the 7th embodiment will be described. First, the problem to be solved by the stepping motor control device 100 according to the 7th embodiment will be described. As described above, the rocking pulse detects the mechanical load by rocking the rotor. In particular, for a gear having normal teeth and load teeth, it is possible to determine whether it is meshing with the normal teeth or the load teeth by detecting the mechanical load. Here, if the energy of the rocking pulse is too large, the rotor may rock even when meshing with the load teeth. Also, if the energy of the rocking pulse is too small, it may not rock even when meshing with the normal teeth. Therefore, it is required that the energy of the rocking pulse be an appropriate energy. In the present embodiment, the energy of the rocking pulse is adjusted to an appropriate energy.

[0179] FIG. 22 is a diagram for explaining the rocking pulse rank control in the seventh embodiment. While referring to this figure, a series of operations of the stepping motor control device 100 according to the seventh embodiment will be described. Note that the gear described in the present embodiment assumes a case where one load tooth is provided for each of the gear for coarse adjustment and the gear for fine adjustment. The description is based on the premise that the gear for coarse adjustment rotates one revolution in 360 [step], and the gear for fine adjustment rotates one revolution in 45 [step]. That is, while the gear for coarse adjustment makes one revolution, the gear for fine adjustment makes eight revolutions. Also, the process described in the present embodiment starts when the power is turned on, and thereafter the control is repeated.

[0180] (Step S311) The stepping motor control device 100 sets the rocking rank sr to 0, the needle movement count ND to 0, and the load count NR to 0 as initial conditions. The rocking rank sr indicates the rank of the energy when rocking the rotor by the rocking pulse. The larger the rocking rank sr, the larger the energy. The needle movement count ND is a counter that is incremented for each step. The needle movement count ND is different from the stable count NS in that it includes both normal teeth and load teeth. The load count NR is the number of times determined to be load teeth during one revolution of the gear.

[0181] (Step S313) After the power is turned on, the stepping motor control device 100 rotates the gear by one revolution (i.e., 360 [step]) to identify the position of the load tooth. After the stepping motor control device 100 stores the position of the load tooth, it proceeds to step S315 with the processing. (Step S315) The stepping motor control device 100 determines whether the number of needle operations ND is 360. When the number of needle operations ND is 360 (step 315; YES), the stepping motor control device 100 proceeds to step S331 with the processing. When the number of needle operations ND is not 360 (step 315; NO), the stepping motor control device 100 proceeds to step S317 with the processing. (Step S317) The stepping motor control device 100 applies a swing pulse to the stepping motor 107.

[0182] (Step S319) The stepping motor control device 100 determines whether the induced voltage VRs is greater than a predetermined threshold value Vcomp. When the induced voltage VRs is greater than the predetermined threshold value Vcomp (step 319; YES), the stepping motor control device 100 proceeds to step S323 with the processing. Also, when the induced voltage VRs is less than or equal to the predetermined threshold value Vcomp (step 319; NO), the stepping motor control device 100 proceeds to step S321 with the processing. (Step S321) The stepping motor control device 100 increments the load count NR. That is, the stepping motor control device 100 counts the number of times determined as the load tooth.

[0183] (Step S323) The stepping motor control device 100 applies a drive pulse to the stepping motor 107. (Step S325) The stepping motor control device 100 increments the number of needle operations ND.

[0184] (Step S331) The stepping motor control device 100 determines whether the load count NR is greater than the maximum load count value NRmax. When the load count NR is greater than the maximum load count value NRmax (Step 331; YES), the stepping motor control device 100 advances the process to Step S341. When the load count NR is less than or equal to the maximum load count value NRmax (Step 331; NO), the process advances to Step S333. (Step S333) The stepping motor control device 100 determines whether the load count NR is less than the minimum load count value NRmin. When the load count NR is less than the minimum load count value NRmin (Step 333; YES), the stepping motor control device 100 advances the process to Step S343. When the load count NR is greater than or equal to the minimum load count value NRmin (Step 333; NO), the process advances to Step S345.

[0185] The maximum load count value NRmax is, for example, 28, and the minimum load count value NRmin is, for example, 9. In this embodiment, while the gear for coarse adjustment rotates one turn, the gear for fine adjustment rotates eight turns. Therefore, during one rotation (360 [step]) of the gear for coarse adjustment, at least nine load teeth are to be determined. Thus, the minimum load count value NRmin is set to 9. Also, since there may be cases where induced voltages are detected a plurality of times continuously as load teeth, the maximum load count value NRmax is set to 28 assuming that detection is performed about three times per tooth. Note that the numbers of the maximum load count value NRmax and the minimum load count value NRmin are arbitrary and may be determined according to, for example, the number of steps of the gear of the load teeth.

[0186] (Step S341) The stepping motor control device 100 adds 1 to the swing rank sr. That is, the stepping motor control device 100 applies a swing pulse with greater energy in subsequent times. (Step S343) The stepping motor control device 100 subtracts 1 from the swing rank sr. That is, the stepping motor control device 100 applies a swing pulse with smaller energy in subsequent times.

[0187] (Step S345) The stepping motor control device 100 determines that the energy of the oscillation pulse is appropriate. The stepping motor control device 100 collates the detected load position with the load position stored in step S313. (Step S351) When the detected position matches the stored position (step 351; YES), the stepping motor control device 100 advances the process to step S361. Also, when the detected position does not match the stored position (step 351; NO), the process advances to step S353. (Step S353) The stepping motor control device 100 corrects the position of the load tooth from the stored position to the detected position.

[0188] (Step S361) The stepping motor control device 100 sets the number of needle operations ND and the number of load operations NR to 0.

[0189] [Summary of the Effects of the Seventh Embodiment] According to the above-described embodiment, by including the control circuit 103, the stepping motor control device 100 controls the rank of the oscillation pulse based on the number of times determined as the load tooth during one rotation of the gear. That is, when the gear having the load tooth rotates one full turn, the stepping motor control device 100 selects which rank of the oscillation pulses with different energies to apply based on the number of times it is determined by the determination circuit 104 that the mechanical load received by the rotor is greater than a predetermined threshold value.

[0190] According to the above-described embodiment, even when the load of the gear train provided in the clock 1 fluctuates, the stepping motor control device 100 can make the energy of the oscillation pulse an appropriate energy by controlling the energy of the oscillation pulse. Therefore, according to the present embodiment, the mechanical load can be accurately determined.

[0191] [Eighth Embodiment] Next, the eighth embodiment will be described. In the eighth embodiment, the processes described in the sixth embodiment and the seventh embodiment are combined. With reference to FIG. 23, the process in the eighth embodiment will be described. FIG. 23 is a diagram for explaining an example in the case of combining drive pulse rank control and swing pulse control in the eighth embodiment. For the process in the eighth embodiment, for the processes similar to those described in the sixth embodiment and the seventh embodiment, the description may be omitted by attaching the same reference numerals. The process described in the sixth embodiment is described as step S200, and the process described in the seventh embodiment is described as step S300.

[0192] (Step S411) As initial conditions, the stepping motor control device 100 sets the swing rank sr to 0, the drive rank dr to 0, the number of needle movements ND to 0, the number of load times NR to 0, the number of stable times NS to 0, and the search S to 0. In the eighth embodiment, in terms of having the search S, it is different from the processes described in the sixth and seventh embodiments. While controlling the rank of the swing pulse, it is not known whether the needle is correctly aligned, so the drive pulse is not controlled. That is, the search S serves as a flag indicating the period during which the rank of the swing pulse is controlled when controlling both the rank of the swing pulse and the rank of the drive pulse.

[0193] (Step S421) When the stepping motor control device 100 is not at the stored load position, it determines whether the search S is 0. The case where the search S is 0 indicates a state where the rank of the swing pulse is not being determined. If the search S is not 0 (i.e., step S421; NO), the process proceeds to step S319 and the drive rank is not controlled. If the search S is 0 (i.e., step S421; YES), the process proceeds to step S223 and the drive rank is controlled.

[0194] (Step S431) The stepping motor control device 100 increments the load count NR. That is, the stepping motor control device 100 counts the number of times determined to be the load teeth. This is the same process as step S321 in the seventh embodiment.

[0195] The stepping motor control device 100 performs the setting of search S from step S451 to step 455. (Step S451) The stepping motor control device 100 sets search S to 1. (Step S453) The stepping motor control device 100 sets search S to 0. (Step S455) The stepping motor control device 100 sets search S to 0.

[0196] [Summary of the effects of the eighth embodiment] According to the above-described embodiment, the stepping motor control device 100 sets search S to 1 during the period of controlling the rank of the oscillation pulse, and does not perform the control of the drive pulse when search S is 1. That is, the stepping motor control device 100 does not perform the control of the drive pulse while controlling the rank of the oscillation pulse. Therefore, according to the above-described embodiment, the stepping motor control device 100 can prevent a situation where the rank of the drive pulse is erroneously determined while controlling the rank of the oscillation pulse.

[0197] Note that all or part of the functions provided by the above-described clock 1 may be recorded as a program on a computer-readable recording medium, and this program may be executed by a computer system. The computer system shall include hardware such as an OS and peripheral devices. Also, the computer-readable recording medium is, for example, a portable medium such as a flexible disk, a magneto-optical disk, a ROM (Read Only Memory), a CD-ROM, a storage device such as a hard disk built into the computer system, or a volatile memory (Random Access Memory: RAM) provided in a server on a network such as the Internet. Note that the volatile memory is an example of a recording medium that holds a program for a certain period of time.

[0198] Also, the above-described program may be transmitted to another computer system via a transmission medium, for example, a network such as the Internet or a communication line such as a telephone line.

[0199] Also, the above program may be a program that realizes all or part of the above-described functions. Note that the program that realizes part of the above-described functions may be a program that can be realized in combination with a program that is pre-recorded in the computer system with the above-described functions, that is, a so-called differential program.

[0200] As described above, the embodiments of the present invention have been described with reference to the drawings. However, the specific configuration is not limited to the above-described embodiments, and design changes and the like within the scope not departing from the gist of the present invention are also included.

Description of Reference Numerals

[0201] 1…Clock, 4…Movement (watch movement), 6…Hour hand (pointer), 20A…First motor (stepping motor), 22…Rotor, 30…First wheel train group (wheel train group), 34b…Third hour intermediate kana (first gear), 42a…24-hour gear (second gear), 61A…First standard tooth, 61B…Second standard tooth, 62…Load tooth, 62A…First load tooth, 100…Stepping motor control device, 101…Oscillation circuit, 102…Dividing circuit, 103…Control circuit, 105…Voltage detection circuit, 106…Motor drive circuit, 107…Stepping motor, 110…Pointer drive unit, 201…Stator, 202…Rotor, 203…Through hole for housing the rotor, 204, 205…Inner notch, 206, 207…Outer notch, 208…Magnetic core, 209…Coil

Claims

1. A drive unit that drives a stepping motor including a rotor that rotates a pointer and a coil that generates a magnetic flux for rotating the rotor; A control unit that outputs a drive pulse for rotating the rotor and a swing pulse for swinging the rotor to the drive unit; A voltage detection unit that detects an induced voltage generated in the coil when the rotor vibrates; A determination unit that determines a mechanical load applied to the rotor based on a result detected by the voltage detection unit; Comprising: Before outputting the drive pulse, the control unit outputs the corresponding swing pulse; The determination unit determines the mechanical load based on a result detected by the voltage detection unit of rotation accompanying the output of the swing pulse; A stepping motor control device.

2. After outputting the swing pulse, the control unit outputs the drive pulse after a predetermined period has elapsed. The stepping motor control device according to claim 1.

3. The determination unit determines whether a first gear that rotates based on the rotation of the rotor is in contact with the load teeth of a second gear having load teeth as the mechanical load. The stepping motor control device according to claim 1 or claim 2.

4. The control unit controls the energy for driving the stepping motor according to the mechanical load determined by the determination unit. The stepping motor control device according to any one of claims 1 to 3.

5. The control unit controls the energy for driving the stepping motor by controlling the output time of the drive pulse. The stepping motor control device according to claim 4.

6. The control unit controls the energy for driving the stepping motor by controlling the excitation method of the stepping motor. The stepping motor control device according to claim 4.

7. The control unit controls the energy for driving the stepping motor by controlling the duty ratio of the drive pulse. The stepping motor control device according to claim 4.

8. The control unit controls the energy for driving the stepping motor by controlling the voltage of the drive pulse. The stepping motor control device according to claim 4.

9. The rocking pulse has energy for rotating the rotor in the first rotation direction, and is either a first rocking pulse for rocking the rotor, or has energy for rotating the rotor in the second rotation direction after the first rocking pulse is output, and is a second rocking pulse for rocking the rotor. The stepping motor control device according to any one of claims 1 to 8.

10. The first rotation direction is the forward rotation direction, and the second rotation direction is the direction opposite to the first rotation direction. The stepping motor control device according to claim 9.

11. When the control unit outputs the rocking pulse according to a predetermined period in which the drive pulse is output, the control unit outputs the first rocking pulse, and when the control unit outputs the rocking pulse at a predetermined timing not according to the predetermined period in which the drive pulse is output, the control unit outputs the first rocking pulse and the second rocking pulse. The stepping motor control device according to claim 10.

12. The determination unit determines the mechanical load received by the rotor based on whether the voltage value detected by the voltage detection unit exceeds a predetermined threshold value. The stepping motor control device according to any one of claims 1 to 11.

13. The determination unit determines the mechanical load received by the rotor based on whether the generation timing of the voltage value detected by the voltage detection unit is within a predetermined period. The stepping motor control device according to any one of claims 1 to 12.

14. The control unit has a rocking pulse output mode for outputting the rocking pulse and a rocking pulse non-output mode for not outputting the rocking pulse. The stepping motor control device according to any one of claims 1 to 13.

15. When the drive pulse is output from the control unit, the drive unit drives the stepping motor with a first voltage, and when the rocking pulse is output from the control unit, the drive unit drives the stepping motor with a second voltage lower than the first voltage. The stepping motor control device according to any one of claims 1 to 14.

16. When the mechanical load received by the rotor determined by the determination unit is less than a predetermined threshold value, among the drive pulses of a plurality of ranks with different energies, the drive pulse of a rank larger than the immediately preceding applied drive pulse is applied. When a result that the mechanical load received by the rotor determined by the determination unit is larger than the predetermined threshold value is continuously obtained a predetermined number of times or more, among the drive pulses of a plurality of ranks with different energies, the drive pulse of a rank smaller than the immediately preceding applied drive pulse is applied. The stepping motor control device according to any one of claims 1 to 15.

17. When the gear having the load teeth makes one revolution, based on the number of times it is determined by the determination unit that the mechanical load received by the rotor is larger than a predetermined threshold value, among the swing pulses of a plurality of ranks with different energies, it is selected which rank of the swing pulses is to be applied. The stepping motor control device according to any one of claims 1 to 16.

18. While the control unit is controlling the rank of the swing pulse, it does not perform the control of the drive pulse. The stepping motor control device according to claim 17.

19. The stepping motor control device according to any one of claims 1 to 18, The stepping motor, A movement comprising.

20. A clock comprising the movement according to claim 19.

21. By applying a drive pulse to a stepping motor comprising a rotor that rotates the pointer and a coil that generates a magnetic flux for rotating the rotor, the rotor is rotated, and by applying a swing pulse to the stepping motor, the rotor is swung, When the rotor vibrates, the induced voltage generated in the coil is detected, Based on the detected result, the mechanical load received by the rotor is determined, Before outputting the drive pulse, the corresponding swing pulse is output, Based on the result detected by the voltage detection unit of the rotation accompanying the output of the swing pulse, the mechanical load is determined. A stepping motor control method.

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