JP5495989B2 - Step motor and step motor apparatus using the same - Google Patents

Description

  The present invention has two stators and one rotor, and in particular, a step motor for a timepiece for continuous hand movement used as a drive source for driving a pointer of an analog electronic timepiece and a step using the same The present invention relates to a motor device.

  As a driving source of an analog electronic timepiece, a so-called step motor (also called a stepping motor, a pulse motor, or a synchronous motor) that rotates in synchronization with an input pulse-shaped driving signal is used. Step motor is adopted.

  The single-phase stepping motor has a rotor made of a permanent magnet, a soft magnetic yoke having a rotor hole into which the rotor is rotatably inserted, and a coil wound around a coil core integrated with the yoke (magnetic core). And a set of stators composed of attached coils, and a pulse current is passed through the coils to rotate the rotor by a certain angle.

Around the rotor hole in the yoke of the stator, a pair of slits or magnetic flux saturation portions that function to apply a driving torque to the rotor by a magnetic field generated by a coil, and a pair of functions that function to apply a holding torque to the rotor An inner notch is provided.
The driving torque is a torque for rotating the rotor, and the holding torque is a torque for determining the rotation direction of the rotor and stabilizing the position of the rotor when the coil is not energized. This holding torque can also prevent the needle from flying due to an impact.

  When the pulse current is applied, the rotor rotates by a certain angle. The time required for the one-step operation is only a few [ms]. The coil is not turned on until the pulse current is supplied again after 1 [s]. Energized and the rotor remains stopped. Such a hand movement is called a step hand movement. Since the energization time is very short, the power consumption is small, and even a small battery used in a wristwatch can drive the pointer over a long period of time. Therefore, single-phase stepping motors are currently used in many watches.

  In addition, it is considered that the hand movement is continuously moving by energizing the pulse current at intervals of several tens [ms] instead of energizing the pulse current at intervals of 1 [s], and increasing the reduction ratio by that period. Can show. Such a hand movement method is called continuous hand movement. Such a hand movement method sees many proposals, and timepieces with such a hand movement are widely used mainly in table clocks and the like, and in recent years are often used in watches. Especially in wristwatches, the one in which the second hand moves continuously every second is the mainstream, and the one in which the second hand moves continuously is particularly attracting attention.

The structure of a conventionally known single-phase stepping motor that performs the above-described hand movement method will be described with reference to FIG.
In FIG. 25, a rotor 103 made of a permanent magnet is rotatably inserted into a rotor hole 1011a provided in a yoke 1011. A magnetic flux saturation portion 1011d necessary for applying a driving torque to the rotor 103 is inserted into the rotor hole 1011a. And an inner notch 1011c for applying a holding torque.
When the direction of the pulse current to the coil 1013 is switched at regular intervals and energy is generated to generate torque that can overcome the holding torque, the rotor can be rotated by 180 [deg] in a constant direction.
The configuration of such a single-phase step motor shown in FIG. 25 is widely known. For example, Patent Document 1 discloses an example.

In such stepping motors, many efforts have been made to increase efficiency and reduce power consumption when driving the rotor. For example, a configuration in which two single-phase stepping motors are stacked in the axial direction of the rotor is known (see, for example, Patent Document 2).
Although the prior art shown in Patent Document 2 does not perform continuous hand movement, it is a step motor capable of forward and reverse rotation by controlling two single-phase step motors.

The prior art shown in Patent Document 2 will be described with reference to FIG.
In FIG. 26, stators 201 and 202 composed of two yokes 2011 and 2021 orthogonal to each other and magnetically separated and two coils 2013 and 2023 are arranged coaxially with respect to the rotor 203. The yokes 2011 and 2021 are provided with rotor holes 2011a and 2021a and inner notches 2011c and 2021c so as to have the same phase relationship with respect to the rotor rotation direction, and rotate by 180 [deg].

  This step motor can be switched between forward rotation and reverse rotation by selecting the energized side from the two coils 2013 and 2023. Since it is only necessary to stack the stators 201 and 202 for a single-phase step motor having a history of manufacturing technology in the rotor axial direction, the structure is easy to manufacture.

  As another example of a configuration in which two single-phase stepping motors are stacked in the axial direction of the rotor, a technique that can efficiently generate high torque and reduce power consumption is also known (for example, Patent Document 3). reference.).

JP 55-4554 A (2nd page, FIG. 1) Japanese Examined Patent Publication No. 7-93807 (2nd page, Fig. 1) JP 2009-189080 A (page 5, FIG. 1)

  In the structure of the conventionally known single-phase step motor shown in FIG. 25, the holding torque acts on the rotor 103, and it is necessary to rotate it by applying a sufficiently high voltage to overcome it. And when the rotor 103 stops, the torque which positions the rotor 103 with a holding torque acts, and it stops in a static stable position, carrying out a damping vibration. Therefore, the fluctuation range of the angular velocity per step becomes very large. In this case, there is a problem that when the hands are moved continuously, the watch user perceives a sense of discomfort as the movement of the second hand. This shake of the second hand becomes noticeable when a long second hand is provided.

FIG. 27 schematically shows the state of the angular velocity waveform per step by ignoring fine velocity fluctuations due to the back electromotive force and considerably simplified. In the figure, 108a and 108b are angular velocity waveforms. The fluctuation range of the angular velocity is indicated by Δωd. The drawing also shows an enlarged portion in which one of the angular velocity waveforms is enlarged. In the enlarged portion, T1 and T2 indicate sections, and α indicates a region.
FIG. 27A shows a state in which the fluctuation range is very large and changes from the positive side to the negative side. FIG. 27B shows an ideal angular velocity waveform with no fluctuation range of angular velocity.

If there is a holding torque acting on the rotor, it is necessary to apply a driving pulse to the coil so that the driving torque exceeds the holding torque when the rotor is driven to rotate. As shown in FIG. 27 (A), the drive torque generated by applying the drive pulse is as follows:
The section T1 is a period until the rotor gets over the section in which the holding torque acts as a load. After that, the section starts to rotate at the static stable position after the rotor starts rotating by the holding torque. Then, the fluctuation of the angular velocity of the rotor occurs in both the section T1 and the section T2. However, the generation factor is different between the section T1 and the section T2.

That is, in the section T1, it is generated because the drive torque tries to overcome the holding torque, and the magnitude of the change (variation width) changes depending on the balance between the holding torque and the effective voltage of the drive pulse. is there. If a driving pulse having a high effective voltage that generates a driving torque that is so large as to easily exceed the holding torque is used, the rotor is likely to rotate but the angular velocity fluctuates.
On the other hand, in the section T2 after the section T1 until the rotor finishes rotating at a predetermined angle, this occurs because the holding torque acts and the rotor eventually stops while performing the damping vibration. The magnitude of the change (variation width) also changes with the size. Note that a region α indicates a region where the angular velocity is negatively changed, and if the holding torque is small, the variation in the angular velocity in the region α is also small.

In order to suppress fluctuations in the angular velocity waveform 108a shown in FIG. 27A, the number of pulses generated per second is increased, and the speed reduction ratio of the train wheel is increased so that the user can recognize the degree of hand shake. Can be made difficult.
However, if this is done, the power consumption increases in proportion to the number of pulses. Therefore, when the conventionally known single-phase step motor shown in FIG. Instead, the problem of short life and frequent battery replacement will occur.

  Even if the second hand of the electronic timepiece is continuously operated by applying the conventional technique shown in Patent Document 2, since the holding torque still acts on the rotor 203, in order to step the hand by 180 [deg], the angular velocity The fluctuation becomes the same as the angular velocity waveform 108a of FIG. 27A, and there is also a problem that the watch user perceives a sense of incongruity as a shake of the second hand.

  The conventional technique shown in Patent Document 3 is a technique that can generate a high torque with high efficiency, but since the holding torque acts on the rotor, there is also a fluctuation range of the angular velocity. In the case of an electronic timepiece equipped with a mechanism for transmitting the rotation of the rotor to the hands as it is, the second hand may be shaken when the second hand is continuously moved.

That is, in order to reduce the fluctuation of the second hand of the electronic timepiece by reducing the fluctuation of the angular velocity of the rotor, the fluctuation of the angular velocity in the section T2 shown in FIG. 27A is improved by reducing the holding torque applied to the rotor. . And if the rotor with such a small holding torque is driven with the drive pulse of a smaller effective voltage, the fluctuation | variation of the angular velocity of the area T1 will be improved.
However, no proposal has been made for a step motor that can operate at an effective voltage at such a low level that the holding torque applied to the rotor is extremely small and that the angular velocity does not fluctuate.

  The present invention solves the above-mentioned problems, and has a characteristic in which the fluctuation range of the angular velocity is small as shown in the angular velocity waveform 108b of FIG. 27B, and the watch user does not make the second hand hand shake uncomfortable. An object of the present invention is to provide a step motor that realizes hand movement, can be driven with low power consumption, and is easy to manufacture, and a step motor device using the step motor.

In order to achieve the above object, the step motor according to the present invention employs the following configuration.

Wind a conductor around a single rotor made of a permanent magnet magnetized with two poles, a soft magnetic yoke having a rotor hole into which the rotor is rotatably inserted, and a coil core integrated with the yoke The two stators are arranged in such a manner that the positions of the rotor holes coincide with each other so that the positions of the rotor holes coincide with each other and are shifted in spatial phase from each other and demagnetized from each other. The first stator and the second stator, and by applying a drive pulse to each coil by a drive means that generates a predetermined drive pulse with an electrical phase shifted in each coil, the rotor is In the step motor to rotate,
Around the rotor holes of the two stators, a pair of slits or a magnetic flux saturation portion that functions to apply a driving torque to the rotor by a magnetic field by the coils is provided, and the non-coil between the two stators and the rotor is not provided. The holding torque for stabilizing the position of the rotor when energized does not occur.

  With such a configuration, since no holding torque is generated, the rotor can be driven with a low effective voltage, and a smooth continuous hand movement with a small fluctuation range of the angular velocity can be realized.

  The pair of slits or the magnetic flux saturation portions provided in the two stators may be in positions where no holding torque is generated for each stator.

  By having such a configuration, the positional relationship of the respective stators at the time of assembly is not required so much accuracy, and an effect of being easy to assemble can be obtained.

  The pair of slits or magnetic flux saturation portions provided in the two stators may be in a position where a holding torque is generated in one stator and the holding torque is canceled by the other stator.

  With such a configuration, it is possible to cancel the holding torque by adjusting the positional relationship of the respective stators at the time of assembly, so that it is possible to have an effect of realizing a smooth continuous hand movement with a small fluctuation range of the angular velocity. .

  Each of the first stator and the second stator is provided with a pair of slits and a pair of inner notches for canceling the holding torque generated by the slits. The pair of slits and the pair of inner notches You may make it provide on the line | wire which passes orthogonally through the center.

  By having such a configuration, the magnetic field from the coil efficiently leaks through the slit and acts on the rotor, so that it can be driven at a lower voltage and can have the effect of reducing power consumption.

  A magnetic flux saturation part may be provided in each of the first stator and the second stator, and the magnetic flux saturation parts provided in the two stators may be provided on a line orthogonal to each other through the center of the rotor hole.

  By having such a configuration, it is not necessary to provide an inner notch in the rotor hole, so that an effect of extending the life of the mold can be obtained.

One stator is provided with a pair of slits and a pair of inner notches for canceling the holding torque generated by the slits on a line perpendicular to the center of the rotor hole. The pair of slits provided in one stator and the magnetic flux saturation part provided in the other stator may be provided on a line perpendicular to the center of the rotor hole.

  By having such a configuration, it is possible to assemble without requiring much accuracy of the positional relationship of the stator at the time of assembly, and it is possible to use only one of the stators without an inner notch. It can also have the effect of extending the life of the mold.

  Of the two stators, the slit provided in one stator and the slit provided in the other stator may be provided on a line orthogonal to each other through the center of the rotor hole.

  By having such a configuration, it is possible to achieve the effects of low power consumption by the slit and realization of smooth continuous hand movement by canceling the holding torque by adjustment at the time of assembly.

  The step motor device according to the present invention employs the following configuration in order to achieve the above object.

  The step motor structure described above, and the drive means includes a drive circuit including two sets of H-bridge circuits by at least four switch elements in order to generate a drive pulse, and the effective voltage of the drive pulse. May be a voltage value that generates a torque larger than the static friction torque or the dynamic friction torque acting as a load on the rotor, and may be a voltage value smaller than the threshold voltage of the MOSFET that constitutes the switch element.

  By having such a configuration, driving is performed with a torque that is slightly higher than the friction torque, so that there is no need for extra acceleration / deceleration and the effect of realizing a smooth continuous hand movement with a small fluctuation range of angular velocity can be achieved.

  The drive unit may include a detection unit that detects rotation and non-rotation of the rotor, and a variable voltage unit that varies the effective voltage of the drive pulse based on the detection result of the detection unit.

  By having such a configuration, correction at the time of non-rotation is possible, so there is no need to always drive with a pulse having sufficient energy, and it is possible to drive with the minimum energy, and there is an effect of low power consumption. be able to.

  The variable voltage means sets the effective voltage to a voltage value that generates a torque larger than the static friction torque when the rotor starts to rotate from a stationary state, and generates a torque larger than the dynamic friction torque when the rotor is continuously rotating. You may make it vary so that it may become the voltage value to generate | occur | produce.

  By having such a structure, it can have the effect that it can drive reliably at the time of starting or resetting.

  The drive pulse excites two coils in 1-2 phase, and the voltage applied to each coil makes the effective voltage value in the two-phase energization section smaller than the effective voltage value in the one-phase energization section. You may do it.

  By having such a configuration, there is no acceleration / deceleration due to excessive energy input in the two-phase energization section, and it is possible to achieve the effect of realizing low power consumption and smooth continuous hand movement.

The step motor according to the present invention has an unprecedented feature that no holding torque is generated between the two stators and the rotor to stabilize the position of the rotor when the coil is not energized. For this reason, the fluctuation range of the angular velocity can be reduced. Thereby, when used for moving the second hand of an electronic timepiece, even if the second hand is a long second hand, the second hand does not shake. Smooth hand movement is possible even when the second hand of the electronic watch moves continuously.
In addition, since the stepping motor device according to the present invention has no holding torque in the stepping motor itself, the effective voltage of the driving pulse applied to each coil can be reduced even during the period in which the rotor starts to be driven. In addition to the small fluctuation range, the power consumption can be further reduced.
Furthermore, since each stator itself is not a complicated structure, it has the effect that it is easy to manufacture.

1 is a perspective view for explaining a step motor according to a first embodiment of the present invention. It is a perspective view which shows the state which isolate | separated the 1st stator and 2nd stator of the step motor of 1st Embodiment of this invention to the rotor axial direction. It is a top view which shows the 1st stator and 2nd stator of the step motor of a 1st embodiment of the present invention side by side. It is a figure for demonstrating the holding torque which acts on a rotor by a stator. It is detail drawing of the rotor hole periphery of the step motor of 2nd Embodiment of this invention. It is detail drawing of the rotor hole periphery of the step motor of 3rd Embodiment of this invention. It is detail drawing of the rotor hole periphery of the step motor of 4th Embodiment of this invention. It is sectional drawing which shows typically a rotor hole periphery for describing 4th Embodiment of this invention. It is sectional drawing which shows typically the rotor hole periphery for demonstrating the demagnetization structure of a stator. It is a figure for demonstrating the drive pulse of a rotor. It is a figure explaining the drive at the time of 1 phase excitation. It is a figure explaining the drive at the time of two-phase excitation. It is a figure explaining the drive at the time of 1-2 phase excitation. It is a figure explaining a drive circuit. It is a figure explaining the characteristic of MOSFET which constitutes a switch element. It is a figure which shows the relationship between an applied voltage and the angular velocity of the rotor at that time. It is a figure explaining the method to lower an applied voltage. It is a block diagram explaining a drive means. It is a figure explaining the algorithm for decreasing an effective voltage gradually at the time of normal hand operation. It is a figure explaining the 2nd drive system at the time of 1-2 phase excitation. It is a figure explaining the change of the power consumption with respect to the energization time ratio in the 2nd drive system at the time of 1-2 phase excitation. It is a figure explaining the 3rd drive system at the time of 1-2 phase excitation. It is a figure explaining the algorithm of a driving method selection. (A) is a figure explaining the drive pulse at the time of high speed drive (B) and the drive pulse at the time of step-like drive. It is a figure explaining a prior art. It is a figure explaining the prior art shown in patent document 2. FIG. It is a typical waveform diagram explaining the state of the angular velocity waveform per step.

The step motor has a configuration in which two stators are vertically stacked on one rotor. The two stators are arranged such that the positions of the respective rotor holes coincide with one rotor, and are superposed with their spatial phases shifted in the axial direction and demagnetized from each other.
The step motor has a function of applying a driving torque to the rotor by the stator, but does not have a function of applying a holding torque to the rotor when the coil is not energized.
Then, such a step motor causes the rotor to rotate by applying a driving torque that slightly exceeds the friction torque acting as a load on the rotor. For this reason, there is no excessive acceleration / deceleration, and the fluctuation range of the angular velocity of the rotor can be small.

There are the following four embodiments for preventing the holding torque from acting on the rotor.
In the first embodiment, a slit and an inner notch are provided in each of the upper and lower stators, and the holding torque is canceled by the respective stators.
In the second embodiment, a holding torque is not generated by providing a magnetic flux saturation portion in each of the upper and lower stators.
In the third embodiment, a slit and an inner notch are provided in one stator, and a magnetic saturation part is provided in the other stator, which is a combination of the configurations of the first and second embodiments.
In the fourth embodiment, a slit is provided in each of the upper and lower stators, and the holding torque generated by each stator is canceled by the arrangement position of the slits provided in the upper and lower stators.
Each embodiment will be described below with reference to the drawings.

[Description of Configuration of First Embodiment: FIGS. 1 to 3]
1 to 3 are diagrams showing the configuration of a step motor according to a first embodiment, FIG. 1 is a perspective view of the step motor, and FIG. 2 is a first stator and a second stator of the step motor shown in FIG. FIG. 3 is a plan view showing the first stator and the second stator arranged side by side on the left and right sides of the stator.

The feature of the step motor of the first embodiment is a configuration in which the holding torque is not applied to the rotor when the coils are not energized in each of the stators stacked vertically.
Specifically, each stator is provided with a pair of slits and a pair of inner notches for canceling the holding torque generated by providing the pair of slits, and the slits and the inner notches are orthogonal to each other. Provided. Thus, the holding torque is not applied to the rotor.

In FIG. 1, 3 is one rotor made of a permanent magnet. 11 is a soft magnetic yoke (magnetic core) having a rotor hole 11a into which the rotor 3 is rotatably inserted, a pair of slits 11b, and a pair of inner notches 11c, 12 is a coil core integrated with the yoke 11, and 13 is a coil. This is a coil in which a conducting wire is wound around the core 12. These constitute the first stator 1.
Similarly, 21 is a soft magnetic yoke having a rotor hole 21a into which the rotor 3 is rotatably inserted, a pair of slits 21b, and a pair of inner notches 21c, 22 is a coil core, and 23 is a coil. 2 stators 2 are formed.
In addition, although the coils 13 and 23 are winding a thin conducting wire, the state is omitted for easy viewing of the drawing.

  And the drive means 30 which applies the predetermined drive pulse which shifted the electric phase to the coil 13 and the coil 23 is provided. The details of the driving means 30 will be described later.

As shown in FIG. 1, the first stator 1 and the second stator 2 are arranged so that the positions of the rotor holes 11 a and 21 a coincide with one rotor 3 and are spatially separated from each other in the axial direction. They are arranged with their phases shifted and demagnetized from each other. The demagnetization of both stators has a gap from a holding member or the like (not shown), but may be demagnetized by inserting a non-magnetic spacer between both stators (not shown). Details of the demagnetization using such a spacer will be described later.
Although not shown, a gear is fixed to the rotor 3, and the driving force is transmitted only by the tooth wheel train up to the second hand.

FIG. 2 is a diagram separated along the axial center line A of the rotor 3 so that the positional relationship between the first stator 1 and the second stator 2 and the configuration around the rotor hole can be easily seen. .
As shown in FIG. 2, the first stator 1 and the second stator 2 described in the present embodiment have the same shape. In the example shown in FIG. 2, the upper second stator 2 is arranged by turning the lower first stator 1 upside down. As described above, although the stators are stacked, the two stators have the same shape, so that there is a feature that a step motor can be easily manufactured.

FIG. 3 is a plan view showing the first stator 1 and the second stator 2 arranged side by side, and is a view for explaining the positional relationship between the slits provided in the respective stators and the inner notches.
As shown in FIG. 3, around the rotor hole 11a in the yoke 11 of the first stator 1, a pair of slits 11b functioning to apply a driving torque to the rotor 3 by the magnetic field by the coil 13, and the pair of slits 11b. A pair of inner notches 11c for canceling the holding torque generated by providing the slit 11b is provided, and these are provided on the center line a and the center line b orthogonal to each other through the center of the rotor hole 11a. Provided. That is, the slit 11b and the inner notch 11c are in a positional relationship shifted by 90 [deg].

  Similarly, a pair of slits 21b functioning for applying a driving torque to the rotor 3 by a magnetic field by the coil 23 and a pair of slits 21b are also provided around the rotor hole 21a in the yoke 21 of the second stator 2. A pair of inner notches 21c for canceling the holding torque generated by the above is provided, and these are provided on each of the center line e and the center line d orthogonal to each other through the center of the rotor hole 21a. That is, the slit 21b and the inner notch 21c are in a positional relationship shifted by 90 [deg].

The inner notches 11c and 21c are cuts formed in the radial direction from the inner periphery of the rotor holes 11a and 21a.
Further, since the center line g and the angle θ shown in FIG. 3 are used for the explanation to be described later, the explanation here is omitted.

  With such a configuration, the holding torque can be canceled by the stators stacked one above the other, and the holding torque can be prevented from acting on the rotor 3.

  Further, a straight line a connecting the slits 11b provided in the pair of yokes 11 of the first stator 1 and a straight line d connecting the pair of slits 21b provided in the yoke 22 of the second stator 2 are made to be orthogonal to each other. The center line c of the coil core 12 of the coil 13 and the center line f of the coil core 22 of the coil 23 are arranged so that the directions thereof are orthogonal to each other on a plane.

  In this way, there is an effect that the fluctuation of the magnitude of the drive torque generated by the interaction between the magnetic field generated by each coil and the magnet of the rotor is reduced, and the angular velocity fluctuation width is reduced.

  As is known, the driving torque changes sinusoidally during the rotation of the rotor. When the two stators are orthogonal to each other, the rotor can be rotated only in a region near the peak of the sinusoidal drive torque. As a result, the fluctuation of the driving torque is reduced, and the width of the fluctuation of the angular velocity is reduced.

As already described, since there is only a tooth wheel train between the rotor 3 and the second hand, the movement of the rotor 3 and the movement of the second hand (not shown) have a one-to-one correspondence. For this reason, if there is excessive acceleration / deceleration in the rotor 3 (if the fluctuation range of the angular velocity of the rotor is large), it will be perceived as a sense of incongruity by the watch user as a swing of the second hand.

[Description of First Embodiment: FIGS. 1 to 4]
Next, the operation of the first embodiment will be described with reference to the drawings.
FIG. 4 is a diagram for explaining the holding torque acting on the rotor by the respective stators. 4a is the holding torque due to the slit of the stator, 4b is the holding torque due to the inner notch, and 4 is the holding torque acting on the rotor by the stator. The horizontal axis represents the rotor rotation angle, and the vertical axis represents the holding torque.

  As shown in FIG. 3, the step motor of the first embodiment has a position rotated by +90 [deg] counterclockwise from the position where the slit 11b is provided as the absolute position origin, and the rotor counterclockwise from the absolute position origin. Assuming that the angle at which 3 rotates is θ, the combined holding torque Th (θ) depending on the rotation angle of the rotor 3 is expressed by Equation 1.

  In Equation 1, Tstator 1 (θ) is a holding torque that acts on the rotor 3 by the first stator 1, and Tstator 2 (θ) is a holding torque that acts on the rotor 3 by the second stator 2. Tstator1_slit (θ + π / 2) is a holding torque by a pair of slits 11b, Tstater1_notch (θ) is a holding torque by a pair of inner notches 11c, Tstater2_slit (θ + π / 2) is a holding torque by a pair of slits 21b, and Tstater2_notch (θ) is a pair. Is the holding torque by the notch 21c.

  FIG. 4 shows that the holding torque is combined to be zero. For example, when the first stator 1 is taken as an example, 4a which is the holding torque Tstator1_slit (θ + π / 2) by the pair of slits 11b is 1 By being combined with 4b that is the holding torque Tstatter1_notch (θ) by the inner notch 11c, 4 that is the holding torque Tstater1 (θ) acting on the rotor 3 by the first stator 1 is canceled and becomes zero.

  Thus, in order to cancel the holding torque Tstatter_slit (θ + π / 2) by the pair of slits 11b, the amplitude of the holding torque Tstater_notch (θ) may be adjusted by adjusting the notch width of the pair of inner notches 11c. . As shown in FIG. 4, the holding torque can be canceled out because the pair of slits 11b and the pair of inner notches 11c are orthogonal to the center of the rotor hole.

In the above description, the first stator 1 is taken as an example. However, as already described, the first stator 1 and the second stator 2 have the same shape, and thus the same applies to the second stator 2. It is.
The relationship of the holding torque in the second stator 2 may be obtained by replacing the sign of the above sentence. The holding torque Tstator2_slit (θ + π / 2) by the pair of slits 21b is 4a, and the holding torque by the pair of inner notches 21c. By being combined with 4b which is Tstatter1_notch (θ), 4 which is the holding torque Tstater2 (θ) acting on the rotor 3 by the second stator 2 is canceled and becomes zero.

  Also in the case of the second stator 2, in order to cancel the holding torque Tstater2_slit (θ + π / 2) due to the pair of slits 21b, the holding torque Tstater2_notch (θ) is adjusted by adjusting the notch width of the pair of notches 21c. The amplitude may be adjusted.

[Summary of positional relationship of each component of the first embodiment]
Here, it is as follows when the positional relationship of each component of 1st Embodiment is put together.
A straight line a connecting the pair of slits 11b of the first stator 1 and a straight line b connecting the pair of inner notches 11c are orthogonal to each other. Similarly, a straight line d connecting the pair of slits 21b of the second stator 2 and a straight line e connecting the pair of inner notches 21c are orthogonal to each other. With this configuration, the holding torque is canceled in each stator.
In addition, the straight line a and the straight line d are also orthogonal, and the center line c of the coil core 12 of the first stator 1 and the center line f of the coil core 22 of the second stator 2 are also orthogonal. With this configuration, fluctuations in the magnitude of the driving torque acting on the rotor can be reduced.

[Description of Effects of First Embodiment]
Here, the effects of the first embodiment are summarized as follows.
In the step motor of the first embodiment, since the holding torque for stabilizing the position of the rotor is not generated between each of the two stators and the rotor when the coil is not energized, the fluctuation range of the angular velocity can be reduced. For this reason, when the hands of the analog electronic timepiece are continuously moved, even if the second hand is a long second hand, the second hand is not shaken, and it is possible to move the hand without any sense of incongruity.

  In the step motor device using the step motor of the first embodiment, the effective voltage applied to the coils 13 and 23 is a voltage value that generates a driving torque that is slightly higher than the friction torque acting as a load on the rotor. Therefore, the rotor can be smoothly rotated with a low effective voltage.

  Furthermore, since the structure of the first stator 1 and the second stator 2 can be the same as the stator structure of a single-phase stepping motor with advanced manufacturing technology, there is an effect that it is easy to manufacture.

  As described above, in each stator, the positions of the slit and the inner notch are determined, and in the overlap between the first stator 1 and the second stator 2, the center lines of the coil cores intersect each other. Although the state is determined, the positional relationship between the stators does not require much accuracy. In the example shown in FIG. 1 to FIG. 3, both stators are shown to be orthogonal to each other. However, when they are overlapped, they are orthogonal to each other with extremely high precision so that a slight error is not allowed. You don't have to do that. Therefore, the step motor of the first embodiment has a structure that does not require high accuracy in assembly and is easier to manufacture.

  In addition, since the two stators are provided with slits 11b and 21b, respectively, the first stator 1 and the second stator 2 can reduce the effective voltage applied to the coils 13 and 23. The magnetic field generated by the valve 23 efficiently leaks and acts on the rotor 3 to generate drive torque. Therefore, the rotor 3 can be driven with lower power consumption.

[Description of Configuration of Second Embodiment: FIG. 5]
Next, the step motor of the second embodiment will be described.
The feature of the step motor of the second embodiment is the configuration in which the holding torque is not applied to the rotor when the coil is not energized in each of the vertically stacked stators, as in the embodiment already described.
Specifically, although each stator includes a pair of magnetic flux saturation portions for driving the rotor, no holding torque is generated by not providing an inner notch.

The configuration of the step motor of the second embodiment will be described with reference to FIG.
FIG. 5 is a detailed view showing only the peripheral portions of the rotor holes 11a and 21a of the first stator 1 and the second stator 2 partially enlarged and vertically arranged, and omitting other components such as coils. In addition, the same code | symbol is attached | subjected to the same structure already demonstrated, and those same description is abbreviate | omitted.
In FIG. 5, two stators are shown one above the other for ease of explanation, but the fact that one rotor 3 is shared by two stators is not changed, and two rotors are There is no reason.

  Around the rotor hole 11 a in the yoke 11 of the first stator 1, only a pair of magnetic flux saturation portions 11 d that function to apply a driving torque to the rotor 3 by a magnetic field generated by the coil 13 is provided. The magnetic flux saturation part 11d is a notch-shaped part provided in the stator. Similarly, only a pair of magnetic flux saturation portions 21 d is provided around the rotor hole 21 a in the yoke 2 of the second stator 2.

In the second embodiment, a straight line connecting a pair of magnetic flux saturation portions 11d provided on the yoke 11 of the first stator 1 is a straight line a1, and a pair of magnetic flux saturation portions 21d provided on the yoke 22 of the second stator 2 is The connecting straight line is defined as a straight line d1. The upper and lower stators are arranged so that the straight line a1 and the straight line d1 are orthogonal to each other.
In FIG. 5, a straight line b1 is shown to be orthogonal to the straight line a1, and a straight line e1 is shown to be orthogonal to the straight line d1.

  The straight lines a1 and d1 shown in FIG. 5 are positioned on the straight line a connecting the pair of slits 11b provided on the yoke 11 and the straight line d connecting the pair of slits 21b provided on the yoke 22 shown in FIG. Since the straight line b1 and the straight line e1 shown in FIG. 5 correspond to the straight line b and the straight line e shown in FIG. 3, respectively, in order to understand the arrangement relationship of the step motors of the second embodiment. Referring to FIG. 3, only the periphery of the rotor holes 11a and 21a may be replaced with the configuration of FIG.

[Description of Operation and Effect of Second Embodiment]
Next, the action of canceling the holding torque in the second embodiment will be described.
The first stator 1 and the second stator 2 are provided with a pair of magnetic flux saturation portions 11d and 21d, respectively, but if no inner notch is provided, no holding torque is generated when the coil is not energized. This is because in a general stepping motor, only the magnetic flux generated from the rotor 3 is insufficient to saturate the magnetic flux saturation portions 11d and 21d. Therefore, in the case of the second embodiment, almost no holding torque is generated in the first stator 1 and the second stator 2 in the respective stators.

Next, the effect will be described.
Also in the second embodiment, since no holding torque is generated, the fluctuation range of the angular velocity can be reduced. Since the first stator 1 and the second stator 2 are provided with a pair of magnetic flux saturation portions 11d and 21d, respectively, the magnetic field from the coils 13 and 23 first saturates the magnetic flux saturation portions 11d and 21d. Otherwise, it will not act on the rotor 3. For this reason, although the effective voltage applied to the coils 13 and 23 cannot be lowered to the same extent as in the first embodiment, it is easier to manufacture than in the first embodiment, and the manufacturing cost can be reduced.

That is, since there is no slit in the stator, each of the yokes 11 and 12 can be composed of a single plate, and the stator can be formed only by pressing.
Furthermore, since there is no inner notch and the periphery of the rotor hole is circular, the press mold can be a simple shape, and its life can be extended. Thereby, it is possible to reduce manufacturing cost.

  Since the first stator 1 and the second stator 2 cancel the holding torque in the respective stators, the phase relationship between the two stators is arranged with high accuracy as in the first embodiment. Since it does not need to be designed and does not require assembly accuracy, the structure is easier to manufacture.

[Description of Configuration of Third Embodiment: FIG. 6]
Next, the step motor of the third embodiment will be described.
The feature of the step motor of the third embodiment is a configuration in which the holding torque is not applied to the rotor when the coil is not energized in each of the vertically stacked stators, as in the embodiment described above.
Specifically, although one stator is provided with a pair of slits and a pair of inner notches so as to be orthogonal to each other to cancel the holding torque, and the other stator has a pair of magnetic flux saturation portions for driving the rotor, By not providing the inner notch, the holding torque is not generated. That is, each stator has the stator structure described in the first embodiment and the stator structure described in the second embodiment.

The configuration of the step motor of the third embodiment will be described with reference to FIG.
FIG. 6 is a detailed view showing only the peripheral portions of the rotor holes 11a and 21a of the first stator 1 and the second stator 2 partially enlarged and arranged in the vertical direction and omitting other components such as coils. In addition, the same code | symbol is attached | subjected to the same structure already demonstrated, and those same description is abbreviate | omitted.
Also, in the same manner as in the embodiment already described, in FIG. 6, two stators are merely shown side by side in the drawing for ease of explanation, and there are not two rotors.

  By providing a pair of slits 11b functioning for applying a driving torque to the rotor 3 by a magnetic field generated by the coil 13 and the pair of slits 11b around the rotor hole 11a in the yoke 11 of the first stator 1 A pair of inner notches 11c for canceling the generated holding torque is provided, and these are provided on each of the center line a and the center line b orthogonal to each other through the center of the rotor hole 11a. That is, the slit 11b and the inner notch 11c are in a positional relationship shifted by 90 [deg].

  Around the rotor hole 21 a in the yoke 21 of the second stator 2, only a pair of magnetic flux saturation portions 21 d that function to apply a driving torque to the rotor 3 by a magnetic field generated by the coil 23 are provided. The magnetic flux saturation part 21d is a notch-shaped part provided in the stator. This magnetic flux saturation part 21d is provided on the line of the center line d2 orthogonal through the center of the rotor hole 21a.

  In the third embodiment, a straight line connecting a pair of slits 11b provided in the yoke 11 of the first stator 1 and a straight line connecting a pair of magnetic flux saturation portions 21d provided in the yoke 22 of the second stator 2 are straight lines. The upper and lower stators are arranged so that d2 is orthogonal to each other.

In FIG. 6, a straight line e2 is shown in a direction orthogonal to the straight line d2. These straight lines d
2 and e2 correspond in position to a straight line d connecting a pair of slits 21b provided in the yoke 22 and a straight line e connecting a pair of inner notches 21c provided in the yoke 22 shown in FIG. In order to understand the arrangement relationship of the stepping motors of the third embodiment, only the periphery of the rotor holes 11a and 21a in the configuration should be replaced with the configuration in FIG. 6 with reference to FIG.

  In the above description, the first stator 1 is provided with the slit and the inner notch, and the second stator 2 is provided with the magnetic flux saturation portion. Of course, the first stator 1 is provided with the magnetic flux saturation portion. And the second stator 2 may be provided with a slit and an inner notch.

[Description of Action and Effect of Third Embodiment]
Next, the action of canceling the holding torque in the third embodiment will be described.
The second stator 2 is provided with a pair of magnetic flux saturation portions 21d, and no holding torque is generated unless an inner notch is provided. The first stator 1 is provided with a pair of slits 11b. As described in FIG. 4 of the first embodiment, the holding torque by the pair of slits 11b is provided so as to be orthogonal thereto. The holding torque by the pair of inner notches 11c is canceled out, and no holding torque is generated. Therefore, in the case of the third embodiment, no holding torque is generated in each of the first stator 1 and the second stator 2.

Next, the effect will be described.
In the third embodiment as well, since no holding torque is generated, the fluctuation range of the angular velocity can be reduced. The first stator 1 is provided with a slit 11b and an inner notch 11c, while the second stator 2 is provided with a pair of magnetic flux saturation portions 21d. As already described, the magnetic field from the coil 23 does not act on the rotor 3 until the magnetic flux saturation part 21d is first saturated. For this reason, the effective voltage applied to the coil 23 cannot be lower than the effective voltage applied to the coil 13, but the effective voltage for driving the coil is the same as that of the first embodiment when viewed with the two stators as a whole. It can be lowered to an intermediate level with the second embodiment.

  Of course, as already described, when the second stator 2 is manufactured, there is an effect that it is easy to manufacture because there is no slit or inner notch. In this third embodiment, the structure of the two stators is different, but since the structure itself in which both the stator is provided with a slit, an inner notch and a magnetic flux saturation part is a known structure, the load at the time of manufacturing the step motor There are not many.

  In addition, since the holding torque is canceled in each of the first stator 1 and the second stator 2, the phase relationship between the two stators is highly accurate as in the first and second embodiments. There is also an advantage that it is not necessary to design so as to be arranged at a low level, and the accuracy of assembly is not so much required.

[Description of Configuration of Fourth Embodiment: FIG. 7]
Next, the step motor of the fourth embodiment will be described.
The feature of the step motor of the fourth embodiment is different from the already described embodiments. Each stator has a holding torque to the rotor, but the generated holding torque depends on the arrangement position of the slits provided in the upper and lower stators. The configuration is such that the holding torque does not act on the rotor when canceling and de-energizing the coil.
Specifically, each of the stators is provided with a pair of slits, and when the two stators are overlapped, both the slits are provided so as to be orthogonal to each other to cancel the holding torque. That is, although holding torque is generated in each stator, the two stators cancel the same.

The configuration of the step motor of the fourth embodiment will be described with reference to FIG.
FIG. 7 is a detailed view showing only the peripheral portions of the rotor holes 11a and 21a of the first stator 1 and the second stator 2 partially enlarged and vertically arranged, and omitting other components such as coils. In addition, the same code | symbol is attached | subjected to the same structure already demonstrated, and those same description is abbreviate | omitted.
Further, in the same manner as in the embodiment already described, in FIG. 7, two stators are merely shown side by side in the drawing for ease of explanation, and there are not two rotors.

Around the rotor hole 11 a in the yoke 11 of the first stator 1, a pair of slits 11 b that function to apply a driving torque to the rotor 3 by a magnetic field by the coil 13 is provided. The pair of slits 11b are provided on a center line a passing through the center of the rotor hole 11a.
Similarly, a pair of slits 21 b that function to apply a driving torque to the rotor 3 by a magnetic field by the coil 23 are also provided around the rotor hole 21 a in the yoke 21 of the second stator 2. The pair of slits 21b are provided on a center line d passing through the center of the rotor hole 21a.

  In the fourth embodiment, a straight line a connecting a pair of slits 11b provided in the yoke 11 of the first stator 1 and a straight line connecting a pair of slits 21b provided in the yoke 22 of the second stator 2 are a straight line d. The upper and lower stators are arranged so that are perpendicular to each other.

  In FIG. 7, a straight line b2 is shown in a direction orthogonal to the straight line a, and a straight line e3 is shown in a direction orthogonal to the straight line d. These straight lines b2 and e3 correspond to the straight line b connecting the pair of inner notches 11c provided in the yoke 11 and the straight line e connecting the pair of inner notches 21c provided in the yoke 22 shown in FIG. Yes. In order to understand the arrangement relationship of the stepping motors of the fourth embodiment, referring to FIG. 3, only the periphery of the rotor holes 11a and 21a in the configuration should be replaced with the configuration of FIG.

  In the fourth embodiment, a pair of slits 11b provided in the yoke 11 of the first stator 1 and a pair provided in the yoke 21 of the second stator 2 in order to cancel the holding torque of each stator by the two stators. These slits 21b need to be orthogonal to each other. That is, the straight line a and the straight line d need to be orthogonal.

[Description of Operation and Effect of Fourth Embodiment: FIGS. 4 and 8]
Next, the action of canceling the holding torque in the fourth embodiment will be described with reference to FIG.
FIG. 8 is a cross-sectional view schematically showing a state cut along the center line g shown in FIG.
The rotor 3 'is composed of a rotor magnet 3a and a rotor kana 3b, and details are omitted. Reference numerals 5, 5a, 5a ′, 5b and 5b ′ denote magnetic fluxes.
The magnetic flux 5 generated in the rotor magnet 3a is divided into the yoke 11 of the first stator 1 and the yoke 21 of the second stator 2 as shown by the arrows on the right side of FIG. 8, and flows as magnetic fluxes 5a and 5b. These magnetic fluxes 5a and 5b return to the rotor magnet 3a as magnetic fluxes 5a 'and 5b' again as shown by arrows on the left side of FIG. 8 through a coil core (not shown) to constitute a magnetic circuit.

  Holding torques having a magnitude proportional to the square of the magnetic flux amount of the magnetic fluxes 5a and 5b are generated in the rotor 3 by the yokes 11 and 21, respectively. In the fourth embodiment, the rotor magnet 3a and the yokes 11 and 21 are provided so that the magnetic flux amounts of the magnetic fluxes 5a and 5b are exactly the same. Therefore, the amplitudes of the holding torques generated in the first stator 1 and the second stator 2 shown in FIG. 7 are equal.

This is considered using the above-described equation (1). The holding torque of the first stator 1 is set as Tstator1 (θ), and the holding torque of the second stator 2 is set as Tstator2 (θ). In this case:
Tstater1_notch (θ) = Tstater2_notch (θ) = 0

  Further, since each pair of slits are arranged orthogonally, when applying the relationship of the holding torque in FIG. 4 described above, 4a in FIG. 4 is Tstat1_slit (θ + π / 2), and 4b is Tstater2_slit. This corresponds to (θ + π / 2). Therefore, the holding torque is zero for the entire motor.

Next, the effect will be described.
In the fourth embodiment as well, since no holding torque is generated, the fluctuation range of the angular velocity can be reduced. The first stator 1 is provided with a pair of slits 11b, and the second stator 2 is provided with a pair of slits 21b. As described above, in order to cause the magnetic flux from the rotor magnet to flow in the same amount in the yoke 11 of the first stator 1 and the yoke 21 of the second stator 2, the accuracy in the axial height direction of the rotor 3 is increased. Therefore, compared with the embodiment described above, a higher accuracy is required for the positional relationship between the stators.
However, since there is no inner notch and the periphery of the rotor hole is circular, the press mold can be a simple shape, and its life can be extended. Further, by adjusting the positional relationship of the respective stators during assembly, the holding torque acting on the rotor can be canceled out, and a smooth continuous hand movement with a smaller angular velocity fluctuation range can be realized.

  In addition, since both the first stator 1 and the second stator 2 are formed with a pair of slits 11b and 21b, effective voltages applied to the coils 13 and 23 compared to the case where the magnetic flux saturation portion is provided. Can be lowered.

[Detailed description of step motor]
In the above, each structure, operation | movement, and effect of the step motor of 1st Embodiment to 4th Embodiment were demonstrated. Next, taking the first embodiment as an example, details of the step motor, the drive circuit and drive method of the step motor device will be described in detail.
First, details of the step motor and a method of driving the rotor will be described with reference to the drawings. Each description will be made with reference to new drawings, but please also refer to FIGS.

[Description of stator demagnetization structure: Fig. 9]
First, a specific example of the stator demagnetization structure will be described with reference to FIG. Although this structure has already been described as an example of demagnetizing using a spacer, it will be described in detail with reference to the drawings.
FIG. 9 is a cross-sectional view schematically showing a state cut along the center line g shown in FIG. FIG. 9A shows a demagnetizing structure example 1, and FIG. 9B shows a demagnetizing structure example 2. FIG. In addition, the same code | symbol is attached | subjected to the same structure already demonstrated, and those same description is abbreviate | omitted.

  In the demagnetization structure example 1 shown in FIG. 9A, the rotor holes 11a and 21a provided in the yoke 11 of the first stator 1 and the yoke 21 of the second stator 2 are formed by the non-magnetic middle seat 6, respectively. Positioning is performed in the radial direction of the rotor 3 '. The center seat 6 accurately determines the distance between the yoke 11 and the yoke 21 in the axial direction of the rotor 3 ′.

Further, in the demagnetization structure example 2 shown in FIG. 9B, the center seat 6 'has a configuration including a spacer 6a and a lower seat 6b. The rotor holes 11a and 21a provided in the yoke 11 of the first stator 1 and the yoke 21 of the second stator 2 are positioned in the radial direction of the rotor 3 'by a non-magnetic lower seat 6b that also serves as a bearing for the rotor kana 3b. doing. Further, in the radial direction of the rotor 3 ′, the distance between the yoke 11 and the yoke 21 is accurately determined by the spacer 6a.

  With the configuration shown in FIG. 9, one rotor and two stator yokes are accurately positioned in the radial and axial directions. For this reason, the torque from each stator to the acting rotor is stabilized, and it becomes possible to drive a continuous hand movement with smaller speed fluctuations.

  The above description is particularly effective when the holding torque generated by one stator is canceled by the holding torque by the other stator as in the case of the fourth embodiment. This is because, in addition to cutting both stators accurately, the amount of magnetic flux to each stator can be made equal.

In the demagnetization structure example 2 shown in FIG. 9, the radial direction and the axial direction of the rotor are positioned by separate parts, and this point is different from the configuration of the demagnetization structure example 1. As in the case of the demagnetization structure example 2, by adopting a configuration in which the lower seat also serves as a bearing for the rotor kana, the number of parts can be reduced and positioning between the parts can be made unnecessary.
As is known, there are few surplus parts inside the electronic timepiece. When the electronic timepiece is a wristwatch, there is no surplus portion, and the periphery of the step motor is crowded with other members. When the stepping motor of the present invention is mounted on such an electronic timepiece, the configurations of the demagnetizing structure example 1 and the demagnetizing structure example 2 may be properly used in view of the shape of the portion to be mounted.

[Detailed Description of Rotor Driving 1: FIGS. 10 to 13]
Next, when the step motor of the present invention is used for continuous hand movement of an electronic timepiece, it will be described with reference to FIGS. The drive pulse will be described separately for 1-phase excitation, 2-phase excitation, and 1-2-phase excitation.

FIG. 10A is a characteristic diagram showing the applied voltage when the potential at one end of the coil is taken as a reference during one-phase excitation drive, and FIG. 10B is the reference at the potential at one end of the coil during two-phase excitation. FIG. 10C is a characteristic diagram showing the applied voltage with reference to the potential at one end of the coil during 1-2 phase excitation, and the applied voltage differs depending on each driving method. Is shown.
11 is a rotor drive sequence diagram during one-phase excitation, FIG. 12 is a rotor drive sequence diagram during two-phase excitation, and FIG. 13 is a drive sequence diagram during 1-2 phase excitation.

The step motor can be operated by one-phase excitation, two-phase excitation, or 1-2-phase excitation as shown in FIGS. 10A to 10C during normal hand movement (in the normal rotation direction). However, the effective voltage applied to the coil differs for each excitation method, and the effective voltage applied to each coil is Vr2 for 1-phase excitation, Vr2 for 1-2-phase excitation, and 1-2-phase excitation. If the case is Vr12, it is necessary to have the following relationship.
Vr2 <Vr12 <Vr1

  Further, the step motor of the present invention cancels or does not generate the holding torque, and since the effective voltage applied to the coil is very small as will be described later, when driving the rotor, there are two coils. At least one of them must be energized at all times. This point is different from the conventional step motor.

[In the case of one-phase excitation: FIG. 10 (A), FIG. 11]
First, the case of 1-phase excitation will be described. Of the coil 13 of the first stator 1 and the coil 23 of the second stator 2, one will be described as coil A and the other as coil B.
In the case of one-phase excitation, as shown in FIG. 10A, by energizing only one of coil A and coil B and applying a rotating magnetic field to the rotor, This is a method of rotating in a predetermined direction. The rotor rotates 360 [deg] in the section tr.

The manner in which the rotor rotates will be described with reference to FIG. This rotating state is a state when the rotor is rotating at a steady rotation, not at the time of starting.
Although the position of the rotor magnetic pole at the time of starting is not fixed, steady rotation is performed by gradually following the rotating magnetic field. By energizing the coil 13 in STEP 1, a magnetic field as indicated by an arrow 5 d is generated in the coil 13 and acts on the rotor 3. Arrow 5c represents the magnetic pole direction of the rotor. The magnetic pole direction of the rotor 3 rotates so as to follow the magnetic field generated by the coil 13, and the state becomes STEP2. In this STEP1, the coil 23 is not energized. As will be described later, since the effective voltage applied to each coil is low, the rotor 3 rotates only within the range in which it can rotate most easily. Therefore, the torque for rotating the rotor 3 in the state of STEP2 is the friction torque. Losing to stop.

  Subsequently, in STEP 2, when the coil 23 is energized, a magnetic field as indicated by an arrow 5 e is generated in the coil 23 and acts on the rotor 3 to be further rotated. Then, the arrow 5c enters the state of STEP3.

  In STEP 3, by energizing the coil 13 in the direction opposite to that of STEP 1, the magnetic field arrow 5d becomes as shown in the figure and acts on the rotor 3 to be further rotated.

  In STEP 4, when the coil 23 is energized in the direction opposite to that of STEP 2, the magnetic field arrow 5e becomes as shown in the figure and acts on the rotor 3 to be further rotated. Then, the arrow 5c is in the state of STEP1.

  Thus, by repeating the operations from STEP1 to STEP4, the rotor 3 continues to rotate in the normal rotation direction.

[In the case of two-phase excitation: FIG. 10 (B), FIG. 12]
Next, the case of two-phase excitation will be described. As shown in FIG. 10B, the coil A and the coil B are rotated by applying a rotating magnetic field to the rotor by repeatedly energizing both the coil A and the coil B at all times. In this case, since both are energized, the effective voltage applied to each coil can be made lower than in the case of one-phase excitation. The rotor rotates 360 [deg] in the section tr.

The manner in which the rotor rotates will be described with reference to FIG. This rotating state is a state when the rotor is rotating at a steady rotation, not at the time of starting.
In STEP 1, by energizing the coil 13 and the coil 23, a magnetic field as indicated by an arrow 5 d is generated in the coil 13 and a magnetic field as indicated by an arrow 5 e is generated in the coil 23, and acts on the rotor 3. The magnetic pole direction of the rotor 3 rotates so as to follow the direction in which the magnetic fields generated by the coil 13 and the coil 23 are combined, and the state becomes STEP2.

  Subsequently, in STEP 2, the direction in which only the coil 23 is energized from the state of STEP 1 is reversed from that in STEP 1, whereby a magnetic field as indicated by the arrow 5 e is generated in the coil 23, and the magnetic field generated by the coil 13 and the coil 23 is generated. The rotor 3 rotates to follow the combined direction. Then, the arrow 5c enters the state of STEP3.

  In STEP 3, the direction in which only the coil 13 is energized from the state of STEP 2 is reversed from that in STEP 2, whereby a magnetic field as indicated by an arrow 5 d is generated in the coil 12, and the magnetic fields generated by the coil 13 and the coil 23 are synthesized. The rotor 3 rotates so as to follow the direction. Then, the arrow 5c becomes the state of STEP4.

  In STEP 4, the direction in which only the coil 23 is energized from the state of STEP 3 is reversed from that in STEP 3, so that a magnetic field as indicated by an arrow 5 e is generated in the coil 23, and the magnetic fields generated by the coil 13 and the coil 23 are synthesized. The rotor 3 rotates so as to follow the direction. Then, the arrow 5c is in the state of STEP1.

  Thus, by repeating the operations from STEP1 to STEP4, the rotor 3 continues to rotate in the normal rotation direction.

[In the case of 1-2 phase excitation: FIG. 10 (C), FIG. 13]
Next, the case of 1-2 phase excitation will be described. As shown in FIG. 10 (C), by rotating the coil A and the coil B in a period in which both are energized and a period in which only one of the coils is energized alternately, a rotating magnetic field is applied to the rotor. This is a rotating method. In this case, since both are energized, the effective voltage applied to each coil can be lowered as compared with the case of one-phase excitation, but cannot be lowered as compared with two-phase excitation. The rotor rotates 360 [deg] in the section tr.

The manner in which the rotor rotates will be described with reference to FIG. This rotating state is a state when the rotor is rotating in a steady state, not at the time of starting or the like.
In STEP 1, by energizing the coil 13 and the coil 23, a magnetic field as indicated by an arrow 5 d is generated in the coil 13 and a magnetic field as indicated by an arrow 5 e is generated in the coil 23, and acts on the rotor 3. The magnetic pole direction of the rotor 3 rotates so as to follow the direction in which the magnetic fields generated by the coil 13 and the coil 23 are combined, and the state becomes STEP2.

  Subsequently, in STEP 2, the energization of the coil 23 is stopped from the state of STEP 1, and the magnetic field generated by energizing only the coil 13 is applied to the rotor 3, thereby rotating the rotor 3. The arrow 5c is in the state of STEP3.

  In STEP 3, the direction in which the coil 23 is energized is reversed from that in STEP 1, so that a magnetic field as indicated by an arrow 5 e is generated in the coil 23, and it follows the direction in which the magnetic fields generated by the coil 13 and the coil 23 are combined. Then, the rotor 3 rotates. Then, the arrow 5c becomes the state of STEP4.

  In STEP 4, the coil 13 is deenergized from the state of STEP 3, and the magnetic field generated by energizing only the coil 23 is applied to the rotor 3, thereby rotating the rotor 3. Then, the arrow 5c becomes the state of STEP5.

  In STEP 5, the direction in which the coil 13 is energized is reversed from that in STEP 3, so that a magnetic field as indicated by an arrow 5 d is generated in the coil 13, and it follows the direction in which the magnetic fields generated by the coil 13 and the coil 23 are combined. Then, the rotor 3 rotates. Then, the arrow 5c becomes the state of STEP6.

  In STEP 6, the energization of the coil 23 is stopped from the state of STEP 5, and the magnetic field generated by energizing only the coil 13 is applied to the rotor 3, thereby rotating the rotor 3. Then, the arrow 5c becomes the state of STEP7.

  In STEP 7, the direction in which the coil 23 is energized is reversed from that in STEP 5, so that a magnetic field as indicated by an arrow 5 e is generated in the coil 23, and it follows the direction in which the magnetic fields generated by the coil 13 and the coil 23 are combined. Then, the rotor 3 rotates. Then, the arrow 5c becomes the state of STEP8.

  In STEP 8, the energization of the coil 13 is stopped from the state of STEP 7, and the magnetic field generated by energizing only the coil 23 is applied to the rotor 3, whereby the rotor 3 is rotated. Then, the arrow 5c is in the state of STEP1.

  Thus, by repeating the operations from STEP 1 to STEP 8, the rotor 3 continues to rotate in the normal rotation direction.

According to the experiments conducted by the inventors, the power consumption can be reduced most in the case of 1-2 phase excitation. This is because the number of steps required for one rotation of the rotor 3 is double that of one-phase excitation or two-phase excitation, so that excessive acceleration / deceleration of the rotor is reduced and energy consumption is suppressed. In addition, the speed fluctuation is the smallest and the movement of the needle is reduced. Therefore, it can be said that the 1-2-phase excitation is the most preferable driving method.
In order to reversely rotate the rotor 3, it is only necessary to change the polarity of either the coil A or the coil B in FIG.

[Description of Drive Circuit Configuration: FIGS. 14 and 15]
Next, a driving circuit for generating a driving pulse in the coil of the stator will be described with reference to the drawings. First, the circuit configuration will be described with reference to the drawings.
14 and 15 are diagrams for explaining a specific example of the drive circuit according to the present invention. FIG. 14 is a drive circuit diagram for applying a drive pulse to each coil, and FIG. 15 is a switch element constituting the drive circuit. FIG. 2 is a voltage-current characteristic diagram of a MOS field effect transistor (hereinafter simply referred to as MOSFET).

The drive circuit 10 shown in FIG. 14 is a circuit that constitutes the drive means 30 shown in FIG. 1, and is an H bridge formed by at least four switch elements 10a, 10b, 10c, and 10d in order to generate drive pulses to be applied to the coils. It consists of a circuit. These switch elements use MOSFETs.
The same number of H bridge circuits as the number of coils of the stator is necessary, and two sets of H bridge circuits corresponding to the coil 13 of the first stator 1 and the coil 23 of the second stator 2 are provided.

  Each H-bridge circuit includes a first power supply line 10g (VDD) for supplying a voltage applied to the coil, a second power supply line 10h (VSS) for supplying a reference voltage (for example, GND), and four switch elements. Are connected to four signal lines 10i that supply the drive voltage signal. The signal line 10i is a signal line that supplies a gate voltage to the gate of the MOSFET of the switch element.

Two column circuits in which two switch elements are connected in series are provided between the first power supply line 10g and the second power supply line 10h. One column circuit has a switch element 10a and a switch element 10c connected in series, and the other column circuit has a switch element 10b and a switch element 10d connected in series.
The switch elements connected in series are connected to each other, and an output line and an output terminal are provided at the connection portion. That is, an output line of one column circuit is an output line 10e, an output terminal Out1 is provided at an end thereof, an output line of the other column circuit is an output line 10f, and an output terminal Out2 is provided at an end thereof. A drive pulse is supplied to the coil by connecting the coil to these output terminals.

In a general stepping motor driving circuit for a wristwatch or the like, four switch elements 10a, 10b, 10c, and 10d are composed of P-channel MOSFETs (hereinafter simply referred to as P-MOSFETs), N, in order to reduce the circuit scale. It is composed of channel MOSFETs (hereinafter simply referred to as N-MOSFETs).
Specifically, since the P-MOSFET is easily switched on the high potential side, it is used on the VDD side, which is the high potential side of the H bridge circuit. Since the N-MOSFET is easily switched on the low potential side, it is arranged on the VSS side which is the low potential side.

  The P-MOSFET is electrically connected between the source and drain when a Low signal (low potential signal) is supplied to the gate, and the N-MOSFET is drained when a High signal (high potential signal) is supplied to the gate. Conduction is established between the sources. The desirable four switch elements 10a, 10b, 10c, and 10d shown in the present embodiment have a circuit configuration in which the switch terminals 10a and 10b are transfer gates and the switch terminals 10c and 10d are N-MOSFETs.

As is known, the transfer gate used for the switch elements 10a and 10b is a circuit in which the sources and drains of the P-MOSFET and N-MOSFET are connected in parallel.
In the example shown in FIG. 14, in the switch elements 10a and 10b, the source side of the P-MOSFET and the drain side of the N-MOSFET are terminals TR1a and TR2a, and the drain side of the P-MOSFET and the source side of the N-MOSFET are Are terminals TR1c and TR2c.
The transfer gates constituting the switch elements 10a and 10b are provided with a logic inversion element at the gate of the P-MOSFET, and operate with the same gate signal as that of the N-MOSFET. As a result, the switching element can handle a wide range of potentials, both high and low.

  In the example shown in FIG. 14, in the switch elements 10c and 10d, the drain side of the N-MOSFET is the terminals TR3a and TR4a, and the source side of the N-MOSFET is the terminals TR3c and TR4c.

  The four switch elements 10a, 10b, 10c, and 10d input a high signal or a low signal to their gates, and their terminals are terminals TR1b, TR2b, TR3b, and TR4b, respectively.

  The drive unit 30 shown in FIG. 1 includes other circuits in addition to the drive circuit 10 shown in FIG. 14, which will be described later. What is important is that the drive circuit 10 includes two sets of H bridge circuits having the same configuration.

FIG. 15 is a diagram schematically showing the relationship between the gate-source voltage VGS of the MOSFET and the drain current ID, which is called the Vgs-Id characteristic of the so-called MOSFET.
As shown in the figure, when a potential difference exceeding the threshold voltage VH is applied between the gate and the source, the MOSFET operates as a switch, and a current starts to flow between the source and the drain almost in proportion to the voltage. The threshold voltage of a MOSFET used as a drive circuit for a general wristwatch step motor is about 0.35 [V] to 0.50 [V].

When the step motor of the present invention is used for a timepiece, during normal operation, the effective voltage of the drive pulse applied to the coil is determined from the relationship of friction torque as will be described later, and is 0.1 [which is smaller than the threshold voltage of the MOSFET. V] to about 0.3 [V]. Therefore, 0.1 [V] is supplied to the first power supply line 10g (VDD) as the effective voltage of the drive pulse.
Note that the signal line 10i for supplying the gate voltage to the switch element has a GND signal of 0 [V] as a Low signal and a battery voltage (for example, 1.5 [V]) used for a wristwatch as a High signal.
A voltage signal having a magnitude of about 0.75 [V], which is about half the voltage from the voltage applied, is applied.

[Description of Operation of Driving Circuit: FIG. 14]
Next, the operation of the drive circuit will be described with reference to FIG.
First, the reason why transfer gates are used for the switch elements 10a and 10b will be described.
Here, let us consider a case in which the switch elements 10a and 10b are constituted by only P-MOSFETs used in a driving circuit for a general wristwatch step motor. In particular, let us consider the case where a low effective voltage is applied by lowering the voltage amplitude by full pulse driving, rather than the case where the effective voltage is lowered by time averaging as in chopper driving.

  When a low signal (in this case, 0 [V]) is supplied to the signal line 10i via the terminals TR1b and TR2b in order to operate the switch element and make the source and drain conductive from the non-energized state, the P-MOSFET Since the potential on the source side (TR1a, TR2a) is as low as the effective voltage 0.1 [V] supplied from the first power supply line 10g, the threshold voltage 0.35 [V] to 0.5 [V] Without generating a potential difference exceeding, drain current does not flow and the device does not operate as a switch.

Because of this situation, the step motor drive circuit of the present invention uses transfer gates for the switch elements 10a and 10b.
In the transfer gate, the N-MOSFET is connected in parallel with the P-MOSFET. In this case, the N-MOSFET side operates as a switch. When a High signal (about 1 [V] in this case) is input to the gate, the potential on the source side (TR1c, TR2c) of the N-MOSFET is switched via the switch elements 10c, 10d (when they are in a conductive state). Since GND (0 [V]) is supplied from the second power supply line 10h, the source-drain voltage is 1 [V], which exceeds the voltage sufficiently. Current flows between the sources.
When a transfer gate is used to lower the effective voltage as a time average by chopper driving or when a high voltage (for example, 1.5 [V]) is applied to the coil to rotate the rotor at a high speed as described later, Instead of the N-MOSFET, a P-MOSFET connected in parallel operates as a switch, so that it is possible to cope with various movements.

Next, it will be described that the effective voltage of the drive pulse applied to the coil is preferably about 0.1 [V] to 0.3 [V] during normal hand movement.
In the description, for the sake of simplicity, it is assumed that a state in which only one coil is applied is assumed. At that time, the balance of the torque acting on the rotor and the balance of the voltage of the applied coil are expressed by the following equation (2).

In Equation 2, θ is the rotation angle of the rotor, ω is the angular velocity of the rotor, i is the current flowing through the coil, K is the torque coefficient (= counterelectromotive force coefficient), J · dω / dt is the inertia load, and Th (θ) is Holding torque, D · ω is speed dependent load, TL is friction torque (static friction torque at start-up, dynamic friction torque at rotation), e is applied voltage to coil, L is coil inductance, R is coil resistance is there.

In addition, the magnitude | size of each torque which acts on a rotor from two coils is equal, the specification of a coil is also equal, and it is supposed that the same applied voltage is applied. The mutual inductance between the coils is omitted as being small.
Since the stepping motor of the present invention has a configuration in which the holding torque Th (θ) does not occur (substantially zero), the angular velocity ω of the rotor and the current i flowing through the coil can be reduced by applying the applied voltage e to the coil from Equation 2. It can be seen that the smaller it is.

  As the angular velocity ω of the rotor and the current i flowing through the coil become smaller, the effects of their differentials dω / dt and di / dt become smaller. Unlike conventional stepping motors that have transient response behavior, they move at very low angular velocities by always applying a driving torque that is slightly higher than the frictional force by minimizing excessive acceleration and deceleration of the rotor. Since this is a drive system, Equation 2 can be rewritten as Equation 3.

  In Equation 3, when one step of the rotor is completed, the angular velocity of the rotor is approximately ω = 0, and Equation 3 is further rewritten as Equation 4 more approximately.

According to an experiment by the inventors, when K = about 6e ⁻⁴ [Vs], R = about 2800 [Ω], and e = about 0.12 [V], i = about 42 [uA], ω = The rotor continued to rotate slowly and smoothly at a very low rotational speed of about 3 [deg / ms].
The rotational speed of the rotor when driving a general single-phase stepping motor for a watch is about 35 [deg / ms]. At this time, when the friction torque TL is calculated from the above equation 4, it is about 2.5e ⁻⁸ [Nm]. However, since the speed is very low, this TL is related to the friction torque and the hysteresis characteristics of the magnetic material of the yoke. This is considered to be torque due to loss.
In the experiment, permalloy with little hysteresis is used for the yoke, and it is considered that most is due to friction torque. Note that the above experimental result is a steady state that continues to rotate, and it is necessary to slightly increase the applied voltage at startup, because this is larger than the friction torque (dynamic friction torque) in the state where the static friction torque is moving. It is believed that there is.

By the way, the width of the pulse to be applied is set by increasing the pulse width so that it can be rotated to a predetermined angle by experiment or the like because the rotor does not rotate to a predetermined angle even if it is too short. Therefore, it does not rotate at a predetermined pulse rate like a known step motor. However, with such a setting method, although it is a synchronous motor that rotates in synchronization with the pulse rate, or a step motor that is a subcategory, it is a DC motor with little transient start and stop and small speed fluctuation. Can be rotated. Therefore, it is possible to realize continuous hand movement with very small speed fluctuation.

[Description of the effect of the drive circuit: FIG. 16]
Next, the effect of the drive circuit will be described with reference to FIG.
FIG. 16 is a diagram schematically showing the relationship between the applied voltage and the angular velocity of the rotor at that time. FIG. 16A shows the relationship of the angular speed of the rotor in the case of the prior art, and FIG. 16B shows the relationship of the angular velocity of the rotor when the small applied voltage of the present invention is applied. In the figure, Δωd is the fluctuation width of the angular velocity of the prior art, and Δωf is the fluctuation width of the angular velocity of the present invention.

If the circuit configuration described with reference to FIG. 14 is used, the switching operation can be made normal even when a small effective voltage as shown in FIG. In the step motor of the present invention, since the holding torque is not generated, it is not necessary to apply a large applied voltage necessary for generating the driving torque. Conventionally known single-phase stepping motors require a large applied voltage exceeding the holding torque, and the angular velocity fluctuation range Δωd has become large as the rotor repeatedly accelerates and decelerates. No action is taken.
Since the drive may always be performed by rotating the drive torque that is slightly higher than the friction torque at all times, there is no extra acceleration / deceleration, and the fluctuation range Δωf of the rotor angular velocity is small.

  By connecting the movement of the angular velocity as shown in FIG. 16 (B) per step, it is possible to realize a needle movement with a small speed fluctuation. That is, when continuous hand movement is performed, the fluctuation of the angular velocity becomes a gentle sine wave, and a waveform close to the target flat angular velocity waveform 108b as shown in FIG. It is.

In the case of the prior art as shown in FIG. 16A, when the applied voltage is Vd [V], the energization time is td [s], and the average current flowing through the coil in that section is id [A], the input energy Ed [J] is Ed = Vd * id * td.
On the other hand, in the case of the present invention shown in FIG. 16B, when the applied voltage is Vf [V], the energization time is tf [s], and the average current flowing through the coil in that section is if [A], the input energy Ef [J] is Ef = Vf * if * tf.

In FIG. 16A, td [s] is small, but Ed [V] and id [A] are large. On the other hand, in FIG. 16B, tf [s] is large, but Ef [V] and if [A] are small.
Although tf cannot be arbitrarily set to set a predetermined pulse rate, and it is necessary to set a pulse having a sufficient width so that the rotor can rotate a predetermined angle, the number of pulses cannot be set as in the conventional technique. The power consumption does not increase proportionally, and continuous hand movement can be realized without increasing the power consumption, which is the input energy, by reducing the applied effective voltage.

  In addition, although it repeats, it is because the step motor of this invention is a structure which does not have holding torque that it can reduce to the grade which applies an applied voltage substantially to friction torque. Since there is no holding torque, the region α (region of negative fluctuation of angular velocity) shown in FIG. 27A does not exist in FIG. 16B, and the fluctuation width Δωf of angular velocity becomes very small. ing.

[Description of Modification of Driving Circuit: FIG. 17]
Next, a method for reducing the effective voltage of the drive circuit will be described with reference to FIG.
The effective voltage referred to in the present invention is not only the voltage amplitude value but also a value obtained by taking a time average considering the time width to be applied.
FIG. 17 is a characteristic diagram schematically showing the relationship of current when a chopper voltage is applied as the applied voltage. FIG. 17A shows the case where the amplitude of the voltage pulse 7c of the applied voltage Va is large, and the applied voltage Va is a battery voltage (for example, 1.5 [V]) as used in a wristwatch and is used as a chopper. The current characteristic 9c is shown.
FIG. 17B shows a current characteristic 9d when the battery voltage is reduced to about half (for example, 0.75 [V]) as a voltage pulse 7d of the applied voltage Vb and a chopper is used.
FIG. 17C shows a current characteristic 9e when the battery voltage is lowered from about 1/10 to 1/15 as a voltage pulse 7e of the applied voltage Vc and applied as a full pulse instead of a chopper.

The effective values Ia, Ib, and Ic of the current characteristics 9c, 9d, and 9e are approximately the same. When the chopper is formed, the effective value can be controlled by adjusting the duty. However, as the applied voltage increases, the effective value cannot be adjusted by the duty unless the fundamental frequency is increased.
For example, in the case of FIG. 17A and FIG. 17B, if the section tg is divided into 30, in FIG. 17A, the effective for 1.5 × 1/30 = 0.05 [V]. In contrast to the voltage resolution only, in FIG. 17B, 0.75 × 1/30 = 0.025 [V], which is twice that of FIG. 17A.

As described above, since the effective voltage value required for the step motor of the present invention is about 0.1 to 0.3 [V], the voltage near 0.175 [V] is set so as to balance the friction torque. In the case of FIG. 17A, only values of 0.15 [V] and 0.20 [V] having a width of 0.05 [V] can be obtained. Since the input energy is proportional to the square of the effective voltage, it fluctuates greatly when the voltage changes by 0.05 [V], and excessive energy is input to the rotation of the rotor or is not effective for the rotation of the rotor. Only enough energy can be input. In addition, there is a problem that the power consumption of the circuit increases as the frequency is increased for chopper driving.
For this reason, in the step motor of the present invention, the applied voltage is set to the friction torque that is greatly affected by variations due to manufacturing errors, etc. It can be said that it is an easy method.

[Description of Driving Means: FIG. 18]
Next, the driving means 30 already described will be described with reference to FIG.
FIG. 18 is a diagram for explaining the configuration of the step motor and the driving means. The same numbers are assigned to the same configurations already described. In FIG. 18, 30a is a variable voltage means, and 30b is a detection means.

  The driving unit 30 applies a driving pulse to the coils 13 and 23, and a detecting unit 30b that detects rotation and non-rotation of the rotor 3 by reading current information flowing from the driving circuit 10 to the coils 13 and 23. And a variable voltage means 30a for changing the effective voltage of the drive pulse based on the detection result of the detection means 30b and changing the duty of the control signal sent to the drive circuit 10.

Next, the operation and effect of the drive unit 30 shown in FIG. 18 will be described.
When the rotor 3 is determined to be non-rotating, the variable voltage means 30a switches the state in which the applied voltage with the effective voltage lowered for normal operation is supplied to the drive circuit 10, and the effective voltage is always increased to rotate. As described above, a generous amount of energy is supplied to the coils 13 and 23. As a method of increasing the effective voltage, a method of increasing the voltage amplitude itself or a method of increasing the duty can be used.

As explained, the step motor of the present invention reduces the effective voltage to a level that matches the friction torque. The friction torque is likely to change with time due to the influence of the environment and the like, and when the friction torque increases, the rotor 3 cannot be rotated. However, if the driving means 30 shown in FIG. 18 is used, a high effective voltage can be supplied to the coil, so that it can always be rotated even during non-rotation.

[Description of Driving Method: FIGS. 10 and 19]
Next, how to control the driving means 30 shown in FIG. 18 will be described with reference to FIGS. 10 and 19.
FIG. 19 shows an algorithm for gradually decreasing the effective voltage during normal hand movement.

  At startup (STEP 1), since static friction torque acts on the rotor and the train wheel, it does not rotate unless a high effective voltage is applied. This voltage is about 0.2 to 0.3 [V]. For example, if the section tr shown in FIGS. 10A to 10C is set to n = 1 and n is determined to have passed a (a is an integer of 2 or more) times (STEP 2), the effective voltage becomes a medium level. Lower (STEP 3). This voltage is about 0.15 [V] to 0.2 [V].

  When it is determined that n has passed b (b is an integer of 2 or more) times (STEP 4), the voltage is lowered to a lower effective voltage (STEP 5). This voltage is about 0.08 [V] to 0.15 [V]. If the rotor continues to rotate at this low effective voltage, the voltage remains as it is, but if it does not rotate, the effective voltage is increased as a process when non-rotation is detected as described above (for example, in this algorithm, (Step 1) The effective voltage is lowered again according to the algorithm of FIG. Of course, the effective voltage may be controlled by duty control of the chopper as described above.

  As described above, by driving with a high effective voltage at the time of start-up or the like and gradually decreasing the effective voltage, reliable rotation and low power consumption can be achieved.

[Description of Second Driving Method at 1-2 Phase Excitation: FIG. 20]
It has already been described with reference to FIGS. 10 to 13 how the stepping motor of the present invention is moved in the forward rotation direction when it is used for continuous hand movement of an electronic timepiece. Here, the second driving method of the driving pulse in the case of 1-2 phase excitation will be described with reference to FIG. This drive method is different from the drive method already described in the time width of the two-phase energization section.
FIG. 20 (A) is a diagram showing the drive pulse of 1-2 phase excitation already described with reference to FIG. 10 (C), and FIG. 20 (B) is the second drive method and is more desirable 1 It is a figure which shows the drive pulse of -2 phase excitation.

  In the 1-2 phase excitation, as shown in FIG. 20A, the section tr2 in which the two-phase energization is performed and the section tr1 in which the one-phase energization is performed are alternately arranged. However, in the second driving method shown in FIG. 20B, a driving pulse is applied so that the width of the two-phase energizing section tr2 is shorter than the one-phase energizing section tr1.

  In the section where the two-phase energization is performed, the drive torque is applied to the rotor by the two coils, so there is a margin in the drive torque. Therefore, by applying a driving pulse as shown in FIG. 20B, rotation can be performed even if the driving torque in the section in which two-phase energization is performed is reduced.

[Explanation of the effect of the second driving method during 1-2 phase excitation: FIG. 21]
Next, the effect of the second driving method will be described with reference to FIG.
In FIG. 21, the vertical axis represents power consumption, and the horizontal axis represents the time ratio between the two-phase energization section and the one-phase energization section. It is a schematic diagram which shows the experimental result obtained in the case of 1st Embodiment about the difference in power consumption by varying the effective voltage applied at each time.

In this figure, 0:10 is the same as 1-phase excitation, 10: 0 is the same as 2-phase excitation, and 5
: 5 is the case of general 1-2 phase excitation. As shown in FIG. 21, when the time ratio between the two-phase energization section and the one-phase energization section is about 3: 7, the power consumption is the lowest.
As described above, these adjustments are easy to control and adjust because it is only necessary to change the time width between the section tr2 and the section tr1.

[Explanation of the third driving method during 1-2 phase excitation: FIG. 22]
In the second driving method described with reference to FIG. 20, the driving torque in the section in which the two-phase energization is performed is reduced by changing the time width of the section in which the two-phase energization is performed, but the description has already been given with reference to FIG. Even in the drive method in which the time widths of the section tr2 and the section tr1 are the same, the drive torque may be lowered by changing the duty, frequency, and effective voltage. This is the third driving method shown in FIG.

In FIG. 22A, in the case of chopper driving, the duty of the two-phase energizing section is made smaller than the duty of the one-phase energizing section, and it is only necessary to change the duty, so that control is most easy.
FIG. 22B is also a case of chopper driving, where the frequency of the two-phase energization section is smaller than the frequency of the one-phase energization section, and the Duty is the same. In this case, it is necessary to increase the frequency, and power consumption increases as compared with the case of FIG. 22A, but there is an advantage that the effective voltage can be adjusted with higher resolution.
FIG. 22C shows the case of driving with a full pulse, and the effective voltage Vf2 in the section tr2 is made smaller than the effective voltage Vf1 in the section tr1 by changing the voltage amplitude. In order to apply such a subtle voltage change, there is a problem that the scale of the step-down circuit becomes somewhat large, but unlike the case of chopper drive, it is difficult for noise to be applied to the current flowing in the coil, and the rotation of the rotor from the current There is an advantage that information can be easily extracted.

[Detailed Description of Rotor Drive 2: FIGS. 23 and 24]
Next, when the step motor of the present invention is used for an electronic timepiece and its hand movement is switched between high speed driving, step-like driving and continuous hand movement, how to move each of them will be described with reference to FIGS. 23 and 24. explain.
FIG. 23 is a diagram for explaining an algorithm for selecting a driving method. FIG. 24A shows an example of a driving pulse during high-speed driving, and FIG. 24B shows an example of a driving pulse during step-like driving. FIG.

Up to now, a method of driving with low power consumption has been described, particularly with respect to continuous movement during normal hand movement, especially with a small speed fluctuation. However, other driving methods are possible by selecting the driving pulse.
In FIG. 23, as an initialization process (STEP 1), a pulse for determining the initial position of the rotor is applied. Subsequently, either forward rotation or reverse rotation is selected (STEP 2). Subsequently, selection is made between high-speed driving and normal hand movement (STEP 3).

  When high speed driving is selected in STEP 3 (selection is based on a signal from an external switch or the like not shown), a high effective voltage (for example, 1.5 [V] of the battery voltage) is applied to the coil, and high frequency high speed hand movement is applied. A pulse (see FIG. 24A) is output (STEP 5). The high-speed hand movement pulse can be used for a chronograph or the like. Unlike the general single phase step motor, the step motor of the present invention divides the magnetic flux from the rotor into two stators, and links the coils. Therefore, since the back electromotive voltage generated in each coil becomes small, especially when rotating at high speed, the limit of the rotational speed determined by the balance between the back electromotive voltage and the power supply voltage is high. Can be driven at a higher speed.

When normal operation is selected in STEP3, next, it is selected whether or not it is stepped operation (STEP4
)
Here, when the step-like hand movement is selected, a step-like hand movement pulse (see FIG. 24B) is applied to the coil with a high effective voltage (for example, 1.5 [V] of the battery voltage) (STEP 6). In FIG. 24B, two-phase excitation is used, but one-phase excitation or 1-2 phase excitation may be used.
For example, the step-shaped hand movement means that the rotor is fed at a high speed for 10 revolutions (section tstep), and then the rotor is kept stopped (section tstay), and the rotor is fed again at a high speed for 10 revolutions after a predetermined cycle, It is a method of moving the needle that keeps the rotor stopped after that. By performing such a hand movement method, the user can recognize as if the needle is stepping.

  When a continuous operation that is not a stepped operation is selected in STEP 4, a continuous operation pulse with a low effective voltage (for example, 0.1 to 0.3 [V]) as described above is applied to the coil (STEP 7).

  As described above, the step motor of the present invention can select a driving method other than the continuous hand movement, and the user can select the hand movement according to the mood.

  As described above, the details of the step motor, the drive circuit, and the drive method of the present invention have been described with reference to the drawings by using the first embodiment as an example, but, of course, they are not limited to the first embodiment. The demagnetization structure and the driving method using the spacer can be used in other embodiments.

  The present invention can be used as a drive source for an electronic timepiece having various hands including a wristwatch. In addition to a battery that uses a primary battery such as a battery as a power source, a battery that uses a combination of a secondary battery and a solar battery, a thermoelectric generator, a mechanical power generation unit, or the like can also be applied.

DESCRIPTION OF SYMBOLS 1 1st stator 2 2nd stator 11, 21 Yoke 11a, 21a Rotor hole 11b, 21b Slit 11c, 21c Notch 11d, 21d Magnetic flux saturation part 12, 22 Coil core 13, 23 Coil 3, 3 'rotor 3a Rotor Magnet 3b Rotor kana 4, 4a, 4b Holding torque 5, 5a, 5b Magnetic flux 5c, 5d, 5e Magnetic field 6 'Middle seat 6a Lower seat 6b Spacer 9c, 9d, 9e Current characteristics 10 Drive circuit 30 Drive means 30a Variable voltage means 30b Detection means

Claims (6)

One rotor composed of permanent magnets magnetized in two poles;
Having two stators comprising a soft magnetic yoke having a rotor hole into which the rotor is rotatably inserted, and a coil in which a conductive wire is wound around a coil core integrated with the yoke;
The two stators are arranged such that the positions of the rotor holes coincide with each other and overlap each other in the axial direction of the rotor with a spatial phase shifted from each other and demagnetized from each other. A stator,
In the step motor that rotates the rotor by applying the driving pulse to each coil by a driving unit that generates a predetermined driving pulse with an electrical phase shifted to each coil.
Around the rotor holes of the two stators, a pair of slits or magnetic flux saturation portions that function to cause a driving torque to act on the rotor by a magnetic field generated by the coils,
The pair of slits or magnetic flux saturation portions provided in the two stators are in a position where a holding torque is generated in one stator and the holding torque is canceled by the other stator.
Between the two stators and the rotor, a holding motor for stabilizing the position of the rotor is not generated when the coil is not energized. One rotor composed of permanent magnets magnetized in two poles;
Having two stators comprising a soft magnetic yoke having a rotor hole into which the rotor is rotatably inserted, and a coil in which a conductive wire is wound around a coil core integrated with the yoke;
The two stators are arranged such that the positions of the rotor holes coincide with each other and overlap each other in the axial direction of the rotor with a spatial phase shifted from each other and demagnetized from each other. A stator,
In the step motor that rotates the rotor by applying the driving pulse to each coil by a driving unit that generates a predetermined driving pulse with an electrical phase shifted to each coil.
Around the rotor holes of the two stators, a pair of slits or magnetic flux saturation portions that function to cause a driving torque to act on the rotor by a magnetic field generated by the coils,
Between the two stators and the rotor, the position of the rotor is reduced when the coil is not energized.
A stepping motor that does not generate holding torque to stabilize the position,
In order to generate the drive pulse, a drive circuit comprising two sets of H bridge circuits by at least four switch elements is provided,
Of the four switch elements, the high-potential side element of the H-bridge circuit is composed of a transfer gate that is a circuit in which the sources and drains of the P-MOSFET and N-MOSFET are connected in parallel.
The effective voltage of the drive pulse is a voltage value that generates a torque larger than the static friction torque or the dynamic friction torque acting as a load on the rotor, and a voltage value that is smaller than the threshold voltage of the MOSFET that constitutes the switch element. There is a step motor device. The drive means includes detection means for detecting rotation and non-rotation of the rotor, and variable voltage means for changing an effective voltage of the drive pulse based on a detection result of the detection means. The step motor device according to claim 2 . The variable voltage means, the effective voltage,
When the rotor starts to rotate from a stationary state, a voltage value that generates a torque larger than the static friction torque is set.
The step motor device according to claim 3, wherein when the rotor is continuously rotating, the step motor device is varied so as to have a voltage value that generates a torque larger than the dynamic friction torque.   The drive pulse excites the two coils in 1-2 phase, and the voltage applied to each of the coils is an effective voltage value in the two-phase energization interval from an effective voltage value in the one-phase energization interval. The step motor device according to any one of claims 2 to 4, wherein the step motor device is also made smaller. Of the two stators, and the said slits provided in said slit and the other of the stator provided on one of said stator, to claim 1, characterized in that provided on a line perpendicular through the center of the rotor hole Step motor described.

Images