JPH09145859A - Pointer type electronic clock - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely rotate a rotor even if the clock main body is reduced in size and thickness by forming a stator width adjusting outer notch in a stator outer peripheral edge part opposite to one of a pair of inner notches for regulating the stable position of the rotor. SOLUTION: A step motor 40 to which a driving signal is sent from a driving circuit 31 comprises a rotor 42 and a stator 43 having a rotor arrangement hole 430. Outer notches 431, 432 for forming magnetic saturation are formed on the outer peripheral edge of the stator 43 to regulate the neutral point P1 and static (dynamic) stable position P2 (P3) of the rotor 42. Further, inner notches 433, 434 are formed on the inner peripheral edges of the arrangement hole 430 to regulate the stable position and the stable direction of the rotor 42. Further, a stator width adjusting outer notch 435 is formed on the outer peripheral edge part of the stator 43 opposite to the notch 434. Thus, the level of rotation detecting induced current I is so high as to surely detect rotation, so that even if the clock main body is reduced in size and thickness, the rotor 42 can be surely rotated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pointer type electronic timepiece. More specifically, the present invention relates to the structure of a step motor for rotationally driving the second hand.

[0002]

2. Description of the Related Art Among the so-called electronic timepieces that use a crystal oscillator or the like as a time reference, in a pointer display type analog crystal wristwatch, as shown in FIG. 12, a stepper motor 40 is provided with a rotor 42 made of a permanent magnet. A stator 43 is arranged sandwiching the stator 43, and a neutral point P of the rotor 42 is arranged on the stator 43.
1. In order to define the static stable position P2 and the dynamic stable position P3, the outer notches 431 and 43 forming the magnetic saturation part.
2 (outer notch for forming a magnetically saturated portion) and inner notches 433 and 434 for obtaining a cogging torque are formed. The step motor 40 configured as described above includes
As shown in, the stator 43 is excited by the N pole and the S pole by the signal output from the drive circuit 31, and rotates the rotor 42 by 180 °. A train wheel 50 is connected to the rotor 42, and a second hand 61 attached to the fourth wheel & pinion 52 intermittently rotates by 6 ° every second.
In order to perform such a rotation operation, the signal output from the drive circuit 30 is a pulse signal V1 in which the current flow is inverted every one second, as shown in FIG. 5A. In such an electronic timepiece, whether or not the second hand 61 normally rotates for one second is determined by detecting an induced current I caused by an overrun of the rotor 42 that occurs when the rotor 42 rotates by one pulse. As shown in FIG. 5B, the rotor 4
Since 2 does not rotate by one pulse, when the level of the induced current I is low, the pulse signal V1 is followed by a high level pulse signal V2 to the step motor 40 to immediately rotate the second hand 61. ing.

[0003]

However, in the analog quartz wristwatch, there is a tendency to reduce the size and thickness of each member in order to reduce the thickness thereof, and such reduction in size adds to the coil resistance and adds to the rotor 42. This causes a decrease in inertial force, a decrease in cogging torque with respect to the rotor 42, and the like. For this reason, as the analog quartz wristwatch is made thinner, the induced current I for rotation detection becomes smaller, and it is difficult to determine the rotation state of the rotor 42 accordingly, so that it is difficult to reliably rotate the rotor 42. There is.

[0004] In view of the above problems, the object of the present invention is to:
By improving the structure of the step motor, it is possible to realize a pointer type electronic timepiece that can surely rotate the rotor even if the timepiece main body is made small and thin and the power consumption is reduced.

[0005]

In order to solve the above problems, according to the present invention, a step motor which is rotationally driven step by step by a drive signal sent from a drive circuit,
A wheel train for a clock that transmits the rotational driving force of the step motor to the second hand to intermittently rotate the second hand step by step,
In a pointer type electronic timepiece having a rotation detection circuit that detects whether or not the second hand has rotated normally based on an induced current generated in the step motor, the step motor includes a pair of magnetic saturation parts around the rotor. A stator to be formed, and formed on an inner peripheral edge of a rotor arrangement hole of the stator,
A pair of inner notches defining a statically stable position of the rotor;
It has an outer notch for stator width adjustment formed in the outer peripheral edge of the stator at a portion facing at least one inner notch of the pair of inner notches.

[0006]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to the accompanying drawings.

(Overall Configuration) FIG. 1 is a schematic configuration diagram showing the overall configuration of a pointer type electronic timepiece according to this embodiment. Since the basic structure of the electronic timepiece of this example is the same as that of the conventional electronic timepiece, portions having common functions will be described with the same reference numerals.

In FIG. 1, a pointer type electronic timepiece 1 of this example is shown.
Is a pointer display type analog quartz wristwatch, and the drive circuit 31 configured in the control circuit 30 supplies the current to the step motor 40 every one second based on the signal transmitted from the crystal oscillator 20. Is configured to deliver a drive signal that reverses the flow. Step motor 40 is 2
A rotor 42 made of a permanent magnet magnetized to a pole, an integral stator 43 having a cylindrical rotor placement hole 430 in which the rotor 42 is placed, and a coil block made up of a magnetic core 44 wound with a coil 41. Has been done. Further, the control circuit 30 is provided with a rotation detection circuit 32 that detects the presence or absence of rotation of the second hand 61 based on the induced current generated in the step motor 40 in conjunction with the rotation of the rotor 42.

(Structure of Step Motor) FIG. 2 is an explanatory view showing the structure of the step motor when the pointer type electronic timepiece of this embodiment is viewed from the back side.

As shown in FIG. 2, an outer peripheral edge of the stator 43 forms a magnetic saturation portion to define a neutral point P1, a static stable position P2, and a dynamic stable position P3 of the rotor 42. Notches 431 and 432 are formed, and inner notches 433 and 434 for obtaining cogging torque are formed on the inner peripheral edge of the rotor arrangement hole 430 formed in the stator 43. The inner notches 433 and 434 define a stable position and a stable direction with respect to the rotor 42.

The static stable position P2 is defined by the inner notches 433, 4
The rotor 42 incorporated in the motor stops at the position where the potential energy is the minimum, which is a position that forms an angle of about 90 ° with respect to the formation position of 34.

The dynamic stable position P3 is located at the outer notches 431, 4
When a current is passed through the coil 41 at a position that forms an angle of about 90 ° with respect to the formation position of 32, the magnetic poles N and S of the rotor 42 rotate toward the dynamic stable position P3. Here, in order to make the rotor 42 rotatable, the static stable position P2 and the dynamic stable position P3 need to be at positions separated by a predetermined angular distance.

Further, in the step motor 40 of this example,
At the outer edge of the stator 43, two inner notches 433, 43
An outer notch 435 for adjusting the stator width is formed by narrowing the stator width A of the portion corresponding to the inner notch 434 of 4 to increase the coil interlinkage magnetic flux in a certain angle range of the rotor 42.

(Structure of Wheel Train and Second Hand Details) As shown in FIGS. 1 and 3, a fifth wheel 51, a fourth wheel 52, a third wheel 53, and a second wheel are mounted on the rotor 42 through a pinion. The driving force transmission system 2 using a train wheel 50 composed of a wheel 54, a rear wheel 55, and a hour wheel 56 is connected, and a shaft 52 of a fourth wheel & pinion 52 among them is connected.
The second hand 61 is fixed to the tip of No. 1, and the minute hand 62 is fixed to the tip of the cylindrical shaft of the center wheel & pinion 54. In addition, the hour wheel 56
An hour hand 63 is fixed to the tip of the cylindrical shaft of. Here, the reduction ratio from the rotor 42 to the fourth wheel 52 is 1/30
Is set to The second hand 61 is configured so that the rotor 42 intermittently rotates by 6 ° when the rotor 42 intermittently rotates by 180 ° every 1 second.

(Second hand movement operation) FIG. 4 is an explanatory view showing the movement of the rotor when the pointer type electronic timepiece of this example is viewed from the back side.

In the step motor 40 of the pointer-type electronic timepiece 1 thus constructed, the drive voltage is applied to the coil 41, and the stator 42 has the N pole, as shown in FIG.
When the S pole is excited, the repulsive force TD on the magnetic poles N and S of the rotor 42 causes the rotor 42 to rotate and the magnetic poles N and S to be rotated.
S moves from the static stable position P2 to the position where the outer notches 431 and 432 are formed. During this period, if the cogging torque acting to return the magnetic poles N and S is Km, the resultant force of the repulsive force TD and the inertial force of the rotor 42 is larger than the cogging torque Km.

Next, as shown in FIG. 4B, the rotor 4
While the two magnetic poles N, S move from the formation positions of the outer notches 431, 432 to the neutral point P1, the magnetic poles N, S of the rotor 42 are
The resultant force of the attraction force TD with respect to S and the inertial force of the rotor 42 is larger than the cogging torque Km (restoring force) with respect to the magnetic poles N and S.

Next, as shown in FIG. 4 (c), the rotor 4
While the two magnetic poles N and S move from the neutral point P1 to the dynamic stable position P3, the attraction force TD of the rotor 42 with respect to the magnetic poles N and S, the inertia force of the rotor 42, and the cogging torque Km with respect to the magnetic poles N and S. (Resilience) is added.

Next, as shown in FIG.
The two magnetic poles N and S move from the dynamic stable position P3 to the static stable position P3.
While moving to 2, the resultant force of the cogging torque Km and the attraction force TD is larger than the inertial force of the rotor 42.

When the magnetic poles N, S of the rotor 42 pass the neutral point P1, the rotor 42 rotates to the static stable position P2 by inertial force without applying torque from the outside. The drive voltage applied is such that the magnetic poles N and S of the rotor 42 move from the static stable position P2 to the neutral point P1.
It is sufficient to apply the voltage only for the time required to move in the angular range of 90 °.

That is, as shown in FIG. 5 (a), the signal output from the drive circuit 31 for driving the step motor 40 is a pulse signal V1 in which the current flow is inverted every second, The pulse width of such a signal is
This corresponds to only the time required for the magnetic poles N and S of No. 1 to move in the 90 ° angle range from the static stable position P2 to the neutral point P1.

(Second hand / rotor rotation detection method) In such an electronic timepiece, the rotor 42 is stopped until the magnetic poles N and S are stopped at the position facing the static stable position P2, as shown in FIG.
As indicated by the arrow Q, the magnetic poles N and S first pass the static stable position P2 and then slightly overrun. Next, the rotor 42 performs reverse rotation so that the magnetic poles N and S return to the static stable position P2, and after transient transient rotation in the forward direction and rotation in the reverse direction are repeated, the magnetic poles N and S become static. Stable position P
Stop at the position facing 2. Therefore, as shown in FIG. 5A, the induced current I corresponding to the rotation of the rotor 42 flows through the drive coil 41. Therefore, if the level is determined by the rotation detection circuit 32, the rotor 42 rotates normally. It is possible to determine whether or not the second hand 61 has rotated normally. For example, FIG.
As shown in (a), since the rotor 42 normally rotates for one pulse, when the level of the induced current I is high, the rotation detection circuit 32 determines that the rotor 42 has normally rotated.

On the other hand, as shown in FIG.
Since the rotor 42 did not rotate by one pulse, when the level of the induced current I is low, the rotation detection circuit 32 determines that the rotor 42 did not rotate normally, and based on this determination result, the drive circuit 31 Following the pulse signal V1, a high level pulse signal V2 is supplied to the step motor 4
0 to rotate the rotor 42 immediately. Therefore,
If this rotation detection is erroneous, the pulse signal V2 is output even though the rotor 42 has rotated normally, so that more pulse signals are output than necessary, which hinders reduction in power consumption. On the other hand, if the pulse signal V2 is not output although the rotor 42 does not rotate normally,
The second hand 61 will be delayed.

(Main effect of the embodiment) In the pointer type electronic timepiece 1 adopting such a detecting method, when each member is made smaller and lighter in order to make it thinner, the coil resistance increases and the rotor 42 is Since the applied inertial force and the cogging torque with respect to the rotor 42 decrease, the level of the induced current I for rotation detection decreases, but in this example, the stator 42 has an inner notch 43.
Since the outer notch 435 for adjusting the stator width is formed in the portion opposed to No. 4, the level of the induced current I for rotation detection is high, so that rotation detection can be reliably performed.

That is, the stepper motor of the present example in which the stator notch 435 for adjusting the stator width is formed in the stator 43,
For the conventional step motor in which the stator notch 435 for adjusting the stator width is not formed in the stator 43,
When the interlinkage magnetic flux at 1 was obtained, the results shown in FIG. 6 were obtained. In such measurement, the outer notches 431, 43
The state in which the magnetic poles N and S of the rotor 42 are oriented with respect to 2 is set as a reference position (rotor rotation angle is 0 deg), and from this state, the angle of the rotor 42 is rotated by 180 ° in steps of 15 °, and the magnetic core at each angle is rotated. The magnetic flux density of the portion was obtained, and the interlinkage magnetic flux in the drive coil 41 was calculated from this value. In FIG. 6, the solid line L1 represents the relationship between the rotor rotation angle and the coil interlinkage magnetic flux in the step motor of this example, and the dotted line L2 represents the relationship between the rotor rotation angle and the coil interlinkage magnetic flux in the conventional step motor. There is.

As can be seen from FIG. 6, the stepper motor 40 of the present example in which the stator notch 435 for adjusting the stator width is formed in the stator 43 and the conventional stepper motor not having the notch 435 for adjusting the stator width are used for rotor rotation. 9 corners
In the vicinity of 0 deg, the coil interlinkage magnetic flux is the same. In contrast, the rotor rotation angle is 130 deg to 180 deg.
In the range of, the step motor of this example in which the stator width adjusting outer notch 435 is formed in the stator 43 is larger than the conventional step motor in which the stator width adjusting outer notch 435 is not formed, as compared with the conventional step motor. Is larger, the inclination is smaller.

Therefore, in the pointer type electronic timepiece 1 of this example, until the magnetic poles N and S face the static stable position P2 (a section corresponding to about 90 deg to about 180 deg of the rotor rotation angle).
Since the electromotive force generated by the rotation of the rotor 42 is small, the force of the electromotive force acting on the rotor 42 as an electromagnetic brake is small. Therefore, in the rotor 42, the magnetic poles N and S largely overrun after the magnetic poles N and S have passed the static stable position P2.
Has a high rotation speed when it reversely rotates so as to face the static stable position P2. Here, when the number of coil turns of the drive coil 41 is N, the angular position of the rotor 42 is θ, the magnetic flux density (coil linkage density) with respect to the angular position θ of the rotor 43 is φ, and time is t, the electromotive force V is , Is expressed by the following equation.

V = N (dφ / dθ)  (dθ / dt) In this equation, even if the magnetic flux change (dφ / dθ) is the same, the rotational speed (dθ / dt) of the rotor is large.
Since the electromotive force (induced current I) generated at this time is large, the rotation detection of the rotor 42 (second hand 61) can be determined more accurately.

Further, the rotor 42 has a large force to stop at the position where the magnetic poles N and S face the static stable position P2 after overrunning. That is, in the drive signal V1, if the pulse width is too narrow or the signal level is too low, the rotor 42 cannot rotate completely, while if the pulse width is too wide or the signal level is too high, the rotor 42 overruns. After that, the magnetic poles N and S may pass the static stable position P2, and may return to the original static stable position P2 even if they are rotated in the reverse direction, and as a result, they may not rotate, but in this example. Since the magnetic poles N and S have a large force to stop at the position facing the static stable position P2, the range where such an abnormality occurs is wider than the conventional step motor in the range of drive conditions for normal rotation. Since the shift is performed, stable hand movement can be performed.

The reason why such an effect is obtained will now be described with reference to FIGS. FIG. 7A shows a state of magnetic flux lines around the rotor when the rotor rotation angle is 150 deg in the conventional step motor, and FIG. 7B shows the rotor rotation angle in the step motor of this example. Shows the state of magnetic flux lines around the rotor when is 150 deg. FIG. 8A shows that the rotor rotation angle is 9 in the conventional step motor.
The state of magnetic flux lines around the rotor at 0 deg is shown, and FIG. 8B shows the state of magnetic flux lines around the rotor when the rotor rotation angle is 90 deg in the step motor of this example. In these figures, in any case, the magnetic flux lines generated from the magnetic poles N and S (magnets) of the rotor 42 are closed around the rotor 42.
Some are closed through the magnetic core 44. Of these magnetic flux lines, the coil interlinkage magnetic flux in FIG. 6 is defined by the magnetic flux lines passing through the magnetic core 44.

As can be seen by comparing the state of magnetic flux lines in the conventional step motor shown in FIG. 7A with the state of magnetic flux lines in the step motor of this example shown in FIG. 7B. Under the condition that the rotor rotation angle is 150 deg, in the step motor of this example, since the stator notch 435 is formed with the outer notch 435 for adjusting the stator width, the stator width A of the portion corresponding to the inner notch 433 is narrowed. There is a tendency that there are few magnetic flux lines passing therethrough. Therefore, as the number of magnetic flux lines that close around the rotor 42 decreases,
It is considered that the number of magnetic flux lines passing through the magnetic core portion increased and the coil interlinkage magnetic flux increased.

On the other hand, the state of magnetic flux lines in the conventional step motor shown in FIG. 8A and the state of magnetic flux lines in the step motor of this example shown in FIG. 8B are compared. As can be seen, under the condition that the rotor rotation angle is 90 deg, the outer notch 431 is formed in the number of magnetic flux lines closed around the rotor 42 in both the step motor of this example and the conventional step motor. It is in the condition specified by the stator width of the part. Therefore, it is considered that the coil interlinkage magnetic flux is the same between the step motor of this example and the conventional step motor.

(Influence of Shape of Outer Notch for Adjusting Stator Width) Next, the outer notch 4 for adjusting stator width is adjusted under the condition that the stator width A of the portion corresponding to the inner notch 434 is made equal.
The effect of the shape of 35 on the coil interlinkage magnetic flux was examined.
In this examination, as shown in FIG.
A step motor having a slightly deeper stator width adjusting outer notch 435 formed at a position corresponding to a position directly in front of the inner notch 434, and as shown in FIG. Of these, a shallow stator width adjusting outer notch 43 is provided at a position corresponding to a corner of the inner notch 434.
5 was used. In carrying out this examination, similarly to the examination results shown in FIG. 6, the state where the magnetic poles N and S of the rotor 42 face the outer notches 431 and 432 is set as the reference position (rotor rotation angle is 0 deg),
From this state, the angle of the rotor 42 is 180 ° in 15 ° increments.
While rotating, the magnetic flux density of the magnetic core portion at each angle was obtained, and the interlinkage magnetic flux in the drive coil 41 was calculated from this value. The result is shown in FIG.

In FIG. 10, the relationship between the rotor rotation angle and the coil interlinkage magnetic flux in the conventional step motor is shown by a dotted line L2, and in the step motor of the present example, the stator width adjustment external part shown in FIG. 9A is shown. The solid line L1 represents the relationship between the rotor rotation angle and the coil linkage flux in the step motor having the notch 435, and the rotor rotation angle and the coil linkage in the step motor having the stator width adjusting outer notch 435 shown in FIG. 9B. The relationship with the magnetic flux is represented by the one-dot chain line L3.

As can be seen in FIG. 10, the inner notch 434
Step motor having a slightly deeper stator width adjusting outer notch 435 formed at a position corresponding to the front face of the step motor, and a step motor having a shallower stator width adjusting outer notch 435 formed at a position corresponding to a corner portion of the inner notch 434. It has been confirmed that the relationship between the rotor rotation angle and the coil interlinkage magnetic flux is substantially the same between the motor and the motor if the stator width A of the portion corresponding to the inner notch 434 is the same.

(Influence of Depth of Cut of Notch for Adjusting Stator Width) Next, under the condition that the shape of the outer notch 435 for adjusting stator width is made substantially the same, the stator width A of the portion corresponding to the inner notch 434 is changed. 0.16mm, 0.21mm,
The effect on the coil flux linkage when changing to 0.26 mm was examined. Also in this examination, similarly to the examination results shown in FIG. 6, the state in which the magnetic poles N and S of the rotor 42 face the outer notches 431 and 432 is set to the reference position (when the rotor rotation angle is 0d.
Eg), the magnetic flux density of the magnetic core portion at each angle is obtained while rotating the angle of the rotor 42 by 180 ° in steps of 15 ° from this state, and from this value the drive coil 41
The interlinkage magnetic flux at was calculated. The result is shown in FIG.

In FIG. 11, the relation between the rotor rotation angle and the coil interlinkage magnetic flux in the conventional step motor is shown by a dotted line L2, and the stator width A of the portion corresponding to the inner notch 434 in the step motor of this example is shown. The relationship between the rotor rotation angle and the coil interlinkage magnetic flux when 0.16 mm is set is indicated by the alternate long and short dash line L
4 and the stator width A of the portion corresponding to the inner notch 434 is 0.21 mm, the relationship between the rotor rotation angle and the coil interlinkage magnetic flux is represented by the solid line L1, and the stator width of the portion corresponding to the inner notch 434 is represented. The relationship between the rotor rotation angle and the coil interlinkage magnetic flux when A is 0.26 mm is represented by the dotted line L5.

As can be seen from FIG. 11, when the rotor rotation angle is in the range of 130 deg to 180 deg, the stator width A
It has been confirmed that the narrower the magnetic flux, the more the magnetic flux linked to the coil increases. Further, it has been confirmed that when the stator width A is as narrow as 0.16 mm, the coil linkage magnetic flux increases from when the rotor rotation angle is around 120 deg.

(Other Embodiments) In this embodiment, the outer notches 431 and 432 are used to form the magnetically saturated portion in the stator 43. However, the stator 43 is divided into two and the magnetically saturated portion is formed by the gap. You may comprise.

[0040]

As described above, in the pointer type electronic timepiece according to the present invention, the stator of the step motor is
Since the inner notch that defines the statically stable position of the rotor and the outer notch that adjusts the stator width at the portion corresponding to this inner notch are formed, the occurrence of the magnetic poles of the rotor when the magnetic pole of the rotor moves toward the statically stable position occurs. The power is small. For this reason, since this electromotive force exerts a small force on the rotor as an electromagnetic brake, the rotor greatly overruns after the magnetic poles have passed the static stable position. Therefore, since the induced current generated when the magnetic pole returns to the static stable position after overrun is large, the rotor rotation can be accurately detected from this induced current. Can be reliably performed. In addition, power consumption can be reduced as much as no useless drive signal is transmitted.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an overall configuration of a pointer type electronic timepiece.

FIG. 2 is an explanatory diagram showing a configuration of a step motor when the pointer type pointer type electronic timepiece according to the embodiment of the present invention is viewed from the back side.

FIG. 3 is a schematic configuration diagram showing a configuration of a train wheel used in a pointer type electronic timepiece.

FIG. 4 is an explanatory diagram showing the operation of the rotor when the pointer-type pointer-type electronic timepiece according to the embodiment of the present invention is viewed from the back side.

FIG. 5 is a waveform diagram of a drive signal output from a drive circuit of a pointer type electronic timepiece and an induced current used for detecting rotation of a rotor (second hand).

6 is a reference position (rotor rotation angle is 0 deg) when the rotor magnetic pole faces the outer notch of the step motor of the present example shown in FIG. 2 and the conventional step motor.
Is a graph showing the magnitudes of coil interlinkage magnetic fluxes when the angle of the rotor is rotated from this state.

FIG. 7 is an explanatory diagram for explaining the reason why there is a difference in the magnitude of the coil interlinkage magnetic flux in the rotor rotation angle range of 130 deg to 150 deg in the measurement result of the coil interlinkage magnetic flux shown in FIG. 6.

8 is an explanatory diagram for explaining the reason why the rotor linkage angle is 90 deg and the magnitude of the coil linkage flux is the same in the measurement results of the coil linkage flux shown in FIG. 6.

FIG. 9 is an explanatory diagram of two stators used to study the influence of the shape of the stator width adjusting notch on the coil interlinkage magnetic flux in the step motor shown in FIG. 2.

10 is a step motor equipped with each stator shown in FIG. 9, in which the rotor magnetic pole is oriented with respect to the outer notch as a reference position (rotor rotation angle is 0 deg), and the rotor angle is rotated from this state. It is a graph which compares and shows the magnitude of the coil interlinkage magnetic flux at this time.

11 is a step motor in which the stator width of a portion corresponding to an inner notch is changed in the step motor shown in FIG. 2, and a state in which a magnetic pole of a rotor faces an outer notch is set to a reference position (rotor rotation angle is 0 deg). ) Is a graph showing the magnitude of the interlinkage of the coil when the rotor angle is rotated from this state.

FIG. 12 is a plan view of a step motor used in a conventional pointer type electronic timepiece.

[Explanation of symbols]

1 ... Pointer type electronic timepiece 31 ... Drive circuit 32 ... Rotation detection circuit 40 ... Step motor 41 ... Coil 42 ... Rotor 43 ... Stator 50 ... Wheel train 61 ... ..Second hand 431, 432 ... Outer notch for forming magnetic saturation part 433, 434 ... Inner notch 435 for defining static stable position of rotor ... Stator formed in a portion corresponding to inner notch Outer notch for width adjustment A ... Width of stator corresponding to inner notch

Claims (1)

[Claims] 1. A step motor that is rotationally driven step by step by a drive signal sent from a drive circuit, and a timepiece that transmits the rotational driving force of the step motor to a second hand to intermittently rotate the second hand step by step. In a pointer type electronic timepiece having a train wheel and a rotation detection circuit for detecting whether or not the second hand normally rotates based on an induced current generated in the step motor, the step motor includes a pair of step motors around the rotor. Of the magnetic saturation part, a pair of inner notches formed in the inner peripheral edge of the rotor arrangement hole of the stator and defining a static stable position of the rotor, and at least one of the pair of inner notches. A pointer type electronic timepiece having an outer notch for adjusting the stator width formed on the outer peripheral edge of the stator at a portion facing the inner notch.