JP2016003877A - Motor control circuit, electronic timepiece, and motor control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control circuit, an electronic clock, and a method for controlling a motor that can surely drive a step motor in a reverse rotation direction and reduce the power consumption.SOLUTION: A motor control circuit 37 includes: a reverse rotation signal outputting section 342 for outputting a reverse direction rotation signal, which has a first pulse controlling a driving circuit 40 for driving a step motor 50 and causing a rotor 52 of the step motor 50 in a normal rotation direction and a second pulse causing the rotor 52 having been rotated in the normal rotation direction by the first pulse to rotate in a reverse rotation direction; a rotation judging circuit 36 for determining whether the rotor 52 has been rotated for one step in the reverse rotation direction by the reverse rotation signal; and a pulse width setting section 343 for setting the pulse width of the first pulse based on the result of determination of the rotation judging circuit 36.

Description

  The present invention relates to a motor control circuit for controlling a step motor, an electronic timepiece, and a motor control method.

In recent years, analog electronic timepieces have become more multifunctional, and accordingly, hands (hour hand, minute hand, second hand, etc.) may be rotated counterclockwise.
For example, in a timepiece having a stopwatch function, when returning a time measurement indicator from a stop position at the end of measurement to a reference position (for example, 12 o'clock position), the movement distance is shorter in the counterclockwise direction than in the clockwise direction. In some cases, the pointer may be rotated counterclockwise to save time and save power. Some watches with multiple functions and a mode hand that indicates the selected mode are designed so that the mode hand can reciprocate. In such watches, the mode hand is turned counterclockwise. Also need to be rotated.
When the pointer is rotated counterclockwise, the step motor is driven in the reverse direction. However, since a step motor for a watch is mainly rotated in the forward direction, it is usually designed to be easily driven in the forward direction but not easily driven in the reverse direction.
For this reason, when the step motor is driven in the reverse rotation direction, a method is used in which the rotor of the step motor is once rotated in the normal rotation direction, which is easy to rotate, and then rebounded, and then rotated in the reverse rotation direction ( For example, see Patent Document 1).
In the timepiece of Patent Document 1, when the rotor is rotated in the reverse rotation direction, the forward rotation pulse P1 is applied, the reverse rotation pulse P2 is applied, and the reverse rotation pulse P3 is further applied.

JP 2002-71843 A

By the way, the hands of analog electronic timepieces vary in size and weight depending on the size and design of the timepiece. For this reason, the moment of inertia of the pointer is also different. However, in the timepiece of Patent Document 1, the pulse width of each pulse (P1, P2, P3) of the reverse rotation signal for rotating the rotor in the reverse rotation direction is fixed and is not changed according to the moment of inertia of the pointer. .
For this reason, when a pointer with a large moment of inertia is applied, the step motor may not be reliably driven in the reverse direction. In addition, even when a pointer with a large moment of inertia is attached, in order to reliably drive the step motor in the reverse direction, for example, it is conceivable to set the pulse width of each pulse of the reverse signal in accordance with the pointer having the maximum moment of inertia. . However, in this case, even when a pointer with a small moment of inertia is attached, the stepping motor is driven with the reverse pulse signal having the same pulse width as that when a pointer with the maximum moment of inertia is attached, which may increase power consumption. There was sex.

  An object of the present invention is to provide a motor control circuit, an electronic timepiece, and a motor control method capable of reliably driving a step motor in the reverse direction and reducing power consumption.

  The motor control circuit of the present invention controls a drive circuit that drives a step motor to rotate a rotor of the step motor in the forward rotation direction, and the rotor rotated in the forward rotation direction by the first pulse. A rotation signal output unit that outputs a rotation signal having a second pulse that rotates the rotation direction in the rotation direction, a rotation determination unit that determines whether the rotor has rotated one step in the rotation direction by the rotation signal, and A pulse width setting unit configured to set a pulse width of the first pulse based on a determination result of the rotation determination unit.

The motor control circuit of the present invention is activated when the electronic timepiece is shipped from a factory. First, the reverse rotation signal output unit controls the drive circuit to output a reverse rotation signal. The reverse signal has a first pulse and a second pulse. Then, the rotation determination unit determines (rotation determination) whether or not the rotor has rotated one step in the reverse rotation direction based on the reverse rotation signal. And a pulse width setting part sets the pulse width of a 1st pulse based on the determination result in a rotation determination part.
The first pulse is a pulse that gives a reaction to the rotor, and rotates the rotor in the normal rotation direction within a range of less than one step. Here, the rotor easily rotates in the forward rotation direction, but in order to rotate the rotor stationary at the static stable position, the rotor has energy corresponding to the moment of inertia such as a pointer that rotates in conjunction with the rotor. It is necessary to input the first pulse. On the other hand, the first pulse is a pulse for causing the rotor to recoil, so that the rotor rotated in the forward rotation direction by the first pulse returns to the original static stable position by the input of the second pulse. Rotate to. Since the second pulse rotates the rotor that has been counteracted by the first pulse in the reverse direction, the influence of variations in the moment of inertia such as the pointer is reduced. Therefore, the second pulse can use a signal having the same pulse width regardless of the type of the pointer or the like.
Therefore, for example, by repeatedly performing the rotation determination while changing the pulse width of the first pulse, even when various types of pointers having different moments of inertia are mounted, the rotor is reliably secured in the reverse direction by one step. It is possible to specify the minimum value of the pulse width of the first pulse that can be rotated at the same time. Therefore, by setting the pulse width of the first pulse to the specified minimum value, the step motor can be reliably driven in the reverse direction, and power consumption for driving the step motor can be reduced.

  In the motor control circuit of the present invention, the pulse width of the first pulse is configured to be changeable within a preset range, and the pulse width setting unit sets the initial value of the pulse width of the first pulse to the range. When the rotation determining unit determines that the rotor has not rotated, the pulse width of the first pulse is increased by a predetermined value, and the rotation determining unit determines that the rotor has rotated. In this case, it is preferable to end the setting of the pulse width without changing the pulse width of the first pulse.

According to the present invention, the pulse width setting unit increases the pulse width of the first pulse by a predetermined value from the minimum value every time it is determined that the rotation determination unit has not rotated. When it is determined that the rotation has been rotated by the rotation determination unit, the setting of the pulse width is terminated without changing the pulse width.
According to this, even when various types of pointers with different moments of inertia are mounted, the pulse width of the first pulse is set to the minimum value within a range in which the rotor can reliably rotate by one step in the reverse direction. it can.
In addition, when the moment of inertia of the pointer is relatively small, the minimum value of the pulse width of the first pulse necessary for rotation is expected to be relatively short. Therefore, the pulse width of the first pulse is set to the maximum value. The minimum value can be identified earlier and the time required for the setting can be shortened compared to the case where the setting is made by gradually shortening the setting.

  In the motor control circuit of the present invention, the pulse width of the first pulse is configured to be changeable within a preset range, and the pulse width setting unit sets the initial value of the pulse width of the first pulse to the range. When the rotation determination unit determines that the rotor has rotated, the pulse width of the first pulse is shortened by a predetermined value, and the rotation determination unit determines that the rotor has not rotated. In this case, it is preferable that the pulse width of the first pulse is increased by the predetermined value and the setting of the pulse width is ended.

According to the present invention, the pulse width setting unit decreases the pulse width of the first pulse by a predetermined value from the maximum value every time it is determined that the rotation determination unit has rotated. When the rotation determining unit determines that the rotation has not been performed, the pulse width is increased by a predetermined value. That is, the pulse width is returned to the value set once before. Then, the setting of the pulse width ends.
According to this, even when various types of pointers with different moments of inertia are mounted, the pulse width of the first pulse is set to the minimum value within a range in which the rotor can reliably rotate by one step in the reverse direction. it can.
Further, when the moment of inertia of the pointer is relatively large, the minimum value of the pulse width of the first pulse necessary for rotation is expected to be relatively long. Therefore, the pulse width of the first pulse is set to the minimum value. The minimum value can be specified earlier and the time required for setting can be shortened as compared with the case where the adjustment is performed by gradually increasing from the first.

  In the motor control circuit according to the aspect of the invention, the rotation determination unit may determine whether the rotor has rotated one step in the reverse direction based on a reverse induction voltage or a reverse induction current generated in the step motor. preferable.

  According to the present invention, since the rotation can be determined by detecting the reverse induced voltage or the reverse induced current, for example, it is not necessary to separately provide a sensor for detecting the rotation of the rotor. For example, a motor control circuit is mounted. The cost of electronic watches can be reduced.

  In the motor control circuit of the present invention, when the reverse induced voltage or the reverse induced current is not reversed in a predetermined period after the second pulse is output, the rotation determining unit moves the rotor in the reverse direction. It is preferable to determine that the rotor has rotated by one step, and when the reverse induced voltage or the reverse induced current is reversed, it is determined that the rotor has not rotated by one step in the reverse direction.

When the rotor can rotate by one step in the reverse rotation direction by the reverse rotation signal, the rotor does not rotate in the forward rotation direction, and therefore the reverse induced voltage or reverse induced current does not reverse (does not transition across 0V or 0A). On the other hand, if the reverse rotation signal cannot be rotated by one step, the reverse induced voltage or the reverse induced current is reversed (transitioning across 0V or 0A) since the rotation is then performed in the forward direction.
Therefore, the rotation determination unit determines that the rotor has rotated by one step if the reverse induction voltage or reverse induction current is not reversed during the predetermined period, and if the reverse induction voltage or reverse induction current is reversed, the rotor Can be determined with high accuracy by determining that the motor has not rotated by one step.
In addition, since it is only necessary to detect whether the reverse induced voltage or the reverse induced current has transitioned across 0 V or 0 A, the processing of the rotation determination unit can be simplified.

  In the motor control circuit of the present invention, the rotation determination unit is configured such that a difference between a maximum value and a minimum value of the reverse induced voltage or the reverse induced current in a predetermined period after the second pulse is output is a predetermined threshold value. It is preferable to determine that the rotor has rotated by one step in the reverse rotation direction when it is less than the predetermined threshold value, and to determine that the rotor has not rotated by one step in the reverse rotation direction when the predetermined threshold value is exceeded.

Here, the maximum value of the reverse induced voltage or the reverse induced current is a value that maximizes the magnitude in the positive direction, and the minimum value is a value that minimizes the magnitude in the positive direction. That is, when the reverse induced voltage or the reverse induced current is negative, the value having the maximum value in the negative direction is the minimum value.
If the rotor can be rotated by one step in the reverse rotation direction by the reverse rotation signal, then the rotor does not rotate in the normal rotation direction. On the other hand, if the rotation cannot be rotated by one step by the reverse rotation signal, the difference in reverse induced voltage or reverse induced current becomes relatively large since the rotation in the forward direction is performed thereafter.
Therefore, the rotation determination unit determines that the rotor has rotated by one step when the difference between the reverse induced voltage or the reverse induced current in the predetermined period is less than the predetermined threshold, and becomes equal to or greater than the predetermined threshold. In this case, by determining that the rotor has not rotated by one step, it is possible to accurately determine whether the rotor is rotating or not.

  The electronic timepiece of the invention includes the motor control circuit, the step motor, and a pointer driven by the step motor.

  According to the motor control circuit, the step motor can be reliably driven in the reverse rotation direction, and the power consumption for driving the step motor can be reduced. Therefore, the reliability of the electronic timepiece having the motor control circuit is improved, In addition, power consumption can be reduced.

The present invention is a motor control method of a motor control circuit for controlling a step motor, wherein a first pulse for controlling a drive circuit for driving the step motor to rotate a rotor of the step motor in a forward rotation direction; A reverse rotation signal output step for outputting a reverse rotation signal having a second pulse for rotating the rotor rotated in the forward rotation direction by the first pulse in the reverse rotation direction; and the rotor rotates by one step in the reverse rotation direction by the reverse rotation signal. A rotation determination step for determining whether or not the rotation has been performed, and a pulse width setting step for setting a pulse width of the first pulse based on a determination result of the rotation determination step.
According to the present invention, similarly to the motor control circuit, the step motor can be reliably driven in the reverse direction, and the power consumption for driving the step motor can be reduced.

It is a figure which shows the electronic timepiece which concerns on 1st Embodiment of this invention. It is a figure which shows the structure of the said electronic timepiece. It is a figure which shows the signal waveform of the reverse rotation signal in the said embodiment. It is a schematic diagram which shows a mode that the rotor in the said embodiment rotates to a reverse rotation direction. It is a schematic diagram which shows a mode that the rotor in the said embodiment rotates to a reverse rotation direction. It is a figure which shows the characteristic of the reverse induced voltage when the rotor in the said embodiment does not rotate. It is a figure which shows the characteristic of the reverse induced voltage when the rotor in the said embodiment rotates. It is a flowchart which shows the pulse width setting process in the said embodiment. It is a flowchart which shows the pulse width setting process which concerns on 2nd Embodiment of this invention. It is a figure which shows the characteristic of the reverse induced voltage when the rotor in 3rd Embodiment of this invention does not rotate. It is a figure which shows the characteristic of the reverse induced voltage when the rotor in the said embodiment rotates.

[First Embodiment]
An electronic timepiece according to a first embodiment of the present invention will be described with reference to the drawings.
[Configuration of electronic clock]
FIG. 1 is a diagram illustrating an electronic timepiece 1 according to the first embodiment.
As shown in FIG. 1, the electronic timepiece 1 includes hands (hour hand 11, minute hand 12, second hand 13) and a dial 14. Furthermore, the electronic timepiece 1 includes a date wheel 21 as a calendar wheel for displaying a date as calendar information from a date window 15 formed on the dial 14.
The electronic timepiece 1 is generally constituted by an outer case 16 and a movement (not shown) housed in the outer case 16, and is a wristwatch type that a user wears on his arm.
FIG. 2 is a diagram illustrating the drive control device 30, the drive circuit 40, and the step motor 50 included in the movement.

[Step motor]
The step motor 50 drives the hands 11 to 13 through gears (not shown).
As shown in FIG. 2, the step motor 50 includes a stator 51 having a rotor accommodating hole 511, a rotor 52 rotatably disposed in the rotor accommodating hole 511, and a magnetic core (not shown) joined to the stator 51. And a coil 53 wound around a magnetic core. The coil 53 has terminals out1 and out2 at both ends. Each terminal is connected to the drive circuit 40. The rotor 52 is magnetized to two poles (S pole and N pole) (see FIGS. 4 and 5), and the stator 51 is formed of a magnetic material.

  When a drive signal is supplied between the terminals at both ends of the coil 53 and a current flows, a magnetic flux is generated in the stator 51. Thus, the rotor 52 rotates by one step (180 degrees) in the forward rotation direction or the reverse rotation direction due to the interaction between the magnetic pole generated in the stator 51 and the magnetic pole of the rotor 52. Then, the hands 11 to 13 are rotated in conjunction with the rotor 52. In the present embodiment, the direction in which the hands 11 to 13 are rotated clockwise by the rotation of the rotor 52 is the forward rotation direction, and the opposite direction is the reverse rotation direction. Here, the rotor 52 is configured to rotate more easily in the forward rotation direction than in the reverse rotation direction.

[Drive control device]
Next, the drive control device 30 that drives the step motor 50 will be described.
As shown in FIG. 2, the drive control device 30 uses an oscillation circuit 32 that outputs a reference pulse having a predetermined frequency using a reference oscillation source 31 such as a crystal resonator, and divides the pulses input from the oscillation circuit 32. A frequency dividing circuit 33, a drive control circuit 34 that controls the driving of the step motor 50, and a rotation determination circuit 36 that determines the rotation state of the rotor 52.
Here, the rotation determination circuit 36 constitutes a rotation determination unit of the present invention. In addition, the drive control circuit 34 and the rotation determination circuit 36 constitute a motor control circuit 37.

[Drive control circuit]
The drive control circuit 34 controls the drive circuit 40 that drives the step motor 50 to output a normal rotation signal output unit 341 that outputs a normal rotation signal that rotates the rotor 52 of the step motor 50 in the normal rotation direction by one step; A reverse rotation signal output unit 342 for controlling the drive circuit 40 to output a reverse rotation signal for rotating the rotor 52 by one step in the reverse rotation direction, and a pulse width setting unit 343 for setting the forward rotation signal and the pulse width of the reverse rotation signal. Prepare.

[Drive circuit]
Here, the drive circuit 40 includes four field effect transistors 41, 42, 43, 44. The transistors 41 and 43 are P-channel, and the transistors 42 and 44 are N-channel. By controlling the on / off of these field effect transistors 41 to 44, current can flow through the coils 53 of the step motor 50 connected between the transistors 41 and 42 and between the transistors 43 and 44, respectively. Can be rotated in the forward or reverse direction.

[Forward rotation signal output section]
The normal rotation signal output unit 341 generates a control signal using pulses of various frequencies input from the frequency divider circuit 33, and controls the drive circuit 40 by the control signal to move the rotor 52 in the normal rotation direction by one step. A normal rotation signal to rotate the minute is output to the coil 53 of the step motor 50. The normal rotation signal is a signal including one rectangular pulse.

[Reverse signal output section]
The reverse rotation signal output unit 342 generates a control signal using pulses of various frequencies input from the frequency divider circuit 33 and controls the drive circuit 40 by the control signal to rotate the rotor 52 by one step in the reverse rotation direction. The reverse rotation signal to be output is output to the coil 53 of the step motor 50.
FIG. 3 is a diagram showing a signal waveform of the reverse rotation signal.
As shown in FIG. 3, the reverse signal is input to terminals out1 and out2 of the coil 53, and includes a repulsion pulse G1, a suction pulse G2, a repulsion pulse G3, and an attenuation pulse Gr.
The repulsion pulse G1 is a pulse that makes a reaction by rotating the rotor 52 in the forward rotation direction (less than one step, less than 180 degrees). That is, the repulsion pulse G1 constitutes the first pulse of the present invention.
The suction pulse G2 is a pulse that rotates the rotor 52 rotated in the forward rotation direction and pulls it back in the reverse rotation direction. That is, the suction pulse G2 constitutes the second pulse of the present invention.
The repulsion pulse G3 is a pulse that rotates the rotor 52 in the reverse rotation direction and boosts the rotation of the rotor 52 that rotates in the reverse rotation direction by the inertia at the time of pulling back.
The attenuation pulse Gr is a pulse that attenuates the rotation of the rotor 52.

4 and 5 are schematic views showing how the rotor 52 rotates in the reverse direction.
As shown in FIGS. 4 and 5, the rotor 52 used in this embodiment is a two-pole rotor in which N poles and S poles are magnetized one by one. A pair of inner notches 512 are provided in the inner periphery of the rotor accommodating hole 511 of the stator 51 so as to face each other in the radial direction. The rotor 52 is statically stable at a position where the line segments along the opposing direction (a pair of magnetic pole directions) of the N-pole and S-pole magnetic poles of the rotor 52 are orthogonal to the line segments passing through the notches 512. Try to maintain a stop (static stable position).
Furthermore, a pair of outer notches 513 are provided on the outer peripheral portion of the stator 51 so as to sandwich the rotor 52. When the coil 53 (FIG. 2) is energized, the line segments along the magnetic pole direction of the rotor 52 become orthogonal to the line segments passing through these outer notches 513, and a stable stop state is obtained at this position. To maintain (dynamic stable position).

As shown in FIG. 4A, when the repulsion pulse G1 is input from the state where the rotor 52 is in the static stable position, the N pole of the rotor 52 is transferred to the stator 51 as shown in FIG. The rotor 52 rotates in the forward rotation direction, repelling the generated N pole. Here, the rotor 52 rotates within a range of less than one step (less than 180 degrees).
Next, when the suction pulse G2 is input, as shown in FIG. 5A, the N pole of the rotor 52 is attracted to the S pole generated in the stator 51, and the rotor 52 rotates in the reverse direction.
Next, when the repulsion pulse G3 is input, as shown in FIG. 5B, the N pole of the rotor 52 repels the N pole generated in the stator 51, and the rotor 52 rotates in the reverse direction. When the attenuation pulse Gr is input, the rotation of the rotor 52 is attenuated, and the rotor 52 stops at the static stable position. As a result, the rotor 52 rotates 180 degrees in the reverse direction from the state shown in FIG.
Here, the rotor 52 easily rotates in the forward rotation direction, but in order to rotate the rotor 52 stationary at the static stable position, the moment of inertia such as a pointer rotating in conjunction with the rotor 52 is obtained. It is necessary to input a repulsion pulse G1 having an energy corresponding to. On the other hand, since the repulsion pulse G1 is a pulse for causing the rotor 52 to recoil, the rotor 52 rotated in the normal rotation direction by the repulsion pulse G1 returns to the original static stable position by the input of the suction pulse G2. It rotates in the reverse direction. Since the suction pulse G2 rotates the rotor 52, which has been counteracted by the repulsion pulse G1, in the reverse direction, the influence of variations in the moment of inertia such as the pointer is reduced. Therefore, the suction pulse G2 can use a signal having the same pulse width regardless of the type of the pointer or the like.
In the present embodiment, the pulse width of the repulsion pulse G1 is configured to be changeable within a preset range, and the pulse widths of the suction pulse G2 and the repulsion pulse G3 are fixed values.

[Pulse width setting section]
The pulse width setting unit 343 sets the pulse widths of the normal rotation signal and the reverse rotation signal.
In the present embodiment, the pulse width setting unit 343 sets the pulse width of the repulsion pulse G1 in the reverse signal within a preset range based on the determination result of the rotation determination circuit 36 described later. The pulse width setting unit 343 sets the pulse widths of the suction pulse G2 and the repulsion pulse G3 to fixed values. In the present embodiment, the pulse width of the repulsion pulse G1 is set to be equal to or smaller than the pulse width of the suction pulse G2.

[Rotation judgment circuit]
The rotation determination circuit 36 determines whether or not the rotor 52 has rotated one step (180 degrees) in the reverse rotation direction based on the reverse rotation signal output by the control by the reverse rotation signal output unit 342.
Specifically, the rotation determination circuit 36 determines whether or not the rotor 52 has rotated one step in the reverse rotation direction based on the reverse induced voltage generated in the coil 53 of the step motor 50 after the reverse rotation signal is output. To do.

  6 and 7 are diagrams illustrating the characteristics of the reverse induced voltage generated in the coil 53 of the step motor 50 when the reverse rotation signal is output. 6 shows characteristics when the rotor 52 does not rotate due to the reverse rotation signal, and FIG. 7 shows characteristics when the rotor 52 rotates due to the reverse rotation signal.

If the rotor 52 cannot be rotated by one step in the reverse rotation direction by the reverse rotation signal (particularly the repulsion pulse G1 and the suction pulse G2), then it rotates in the forward rotation direction, so that the reverse induced voltage is reversed as shown in FIG. . That is, the reverse induced voltage transitions across the 0 V line from the plus side to the minus side or from the minus side to the plus side.
For this reason, the rotation determination circuit 36 assumes that the predetermined period after the suction pulse G2 is output is a detection interval, and the rotor 52 has not rotated one step in the reverse rotation direction when the reverse induced voltage is reversed in the detection interval. judge.
Further, if the rotor 52 can be rotated by one step in the reverse rotation direction by the reverse rotation signal (particularly the repulsion pulse G1 and the suction pulse G2), then it does not rotate in the normal rotation direction. The direction is not reversed.
For this reason, the rotation determination circuit 36 determines that the rotor 52 has rotated one step in the reverse direction when the reverse induced voltage is not reversed in the detection section.
When the reverse induced current is detected instead of the reverse induced voltage and the reverse induced current is reversed in the detection section (when the transition is made across the 0 A line), the rotor 52 rotates in the reverse direction by one step. If it is determined that there is no reverse induced current in the detection section, it may be determined that the rotor 52 has rotated one step in the reverse direction.

[Pulse width setting process]
Next, a pulse width setting process for setting the pulse width of the reverse signal will be described.
FIG. 8 is a flowchart showing the pulse width setting process.
In this embodiment, the pulse width setting process is executed before the electronic timepiece 1 is shipped from the factory. Here, when the pulse width setting process is executed, the initial value of the pulse width of the repulsion pulse G1 of the reverse rotation signal is set to the minimum value in the changeable range.
When the pulse width setting process is started, the reverse signal output unit 342 controls the drive circuit 40 to output a reverse signal (reverse signal output step: S11).
Next, the rotation determination circuit 36 determines whether or not the direction of the reverse induced voltage generated in the coil 53 of the step motor 50 has been reversed in the detection section, and whether or not the rotor 52 has rotated one step in the reverse direction. (Rotation determination step: S12).

  If NO is determined in S12, since the rotor 52 has not been rotated by one step in the reverse rotation direction, the pulse width setting unit 343 increases the repulsion pulse G1 included in the reverse rotation signal in order to increase the rotational force in the reverse rotation direction. Is set longer by a predetermined value (for example, 0.24 ms) (pulse width setting step: S13). Then, the drive control circuit 34 returns the process to S11. That is, the processing of S11 to S13 is repeatedly executed until it is determined in S12 that the rotor 52 has rotated one step in the reverse rotation direction.

When the rotation determination circuit 36 determines that the rotor 52 has rotated one step in the reverse rotation direction (YES in S12), the pulse width setting unit 343 sets the pulse width of the repulsion pulse G1 included in the reverse rotation signal. The determined value is confirmed (S14).
Thereby, the pulse width of the repulsion pulse G1 can be set to a minimum value within a range in which the rotor 52 reliably rotates by one step in the reverse rotation direction. The set value of the pulse width of the repulsion pulse G1 is stored in a storage unit (not shown) of the motor control circuit 37.
If YES is determined in S12, the pointer rotates by one step in the reverse direction from the initial position determined as the needle position at the time of factory shipment. Therefore, the normal rotation signal output unit 341 controls the drive circuit 40 to output a normal rotation signal (S15) and returns the pointer to the original position. Then, the drive control circuit 34 ends the pulse width setting process.
When the user uses the electronic timepiece 1 and the reverse rotation of the hands 11 to 13 is necessary, the reverse rotation signal output unit 342 outputs the repulsion pulse G1 whose pulse width is set by the pulse width setting process. The reverse rotation signal is output, and the step motor 50 is driven in the reverse rotation direction.

[Effects of First Embodiment]
Each time the rotation determination circuit 36 determines that the rotor 52 has not rotated, the pulse width setting unit 343 increases the pulse width of the repulsion pulse G1 by a predetermined value from the minimum value, and determines that the rotor 52 has rotated. Then, the setting of the pulse width is finished without changing the pulse width. For this reason, even when various types of pointers having different moments of inertia are mounted, the pulse width can be set to the minimum value within a range in which the rotor 52 reliably rotates by one step in the reverse rotation direction. Therefore, the step motor 50 can be reliably driven in the reverse direction, and power consumption for driving the step motor 50 can be reduced.
In addition, when the moment of inertia of the pointer is relatively small, the minimum value can be specified earlier compared with the case where the setting is performed by gradually shortening the pulse width of the first pulse from the maximum value, and the time required for the setting Can be shortened.

  The rotation determination circuit 36 determines, for example, whether or not the rotor 52 has rotated one step in the reverse direction based on the reverse induced voltage generated in the step motor 50. For example, a sensor for detecting the rotation of the rotor 52 The cost of the electronic timepiece 1 can be reduced.

The rotation determination circuit 36 determines that the rotor 52 has rotated one step in the reverse rotation direction when the reverse induction voltage is not reversed in the detection period of the reverse induction voltage, and if the reverse induction voltage is reversed, the rotor 52 is Since it is determined that the motor has not rotated by one step in the reverse direction, it is possible to accurately determine whether the rotor 52 is rotating or not. In addition, since it is only necessary to detect whether the reverse induced voltage has transitioned across 0 V, the processing of the rotation determination circuit 36 can be simplified.
Note that the same effect can be obtained when the determination is made based on the reverse induced current instead of the reverse induced voltage.

[Second Embodiment]
The electronic timepiece of the second embodiment is different from the first embodiment in the pulse width setting process. Other configurations are the same as those of the first embodiment.
FIG. 9 is a flowchart showing a pulse width setting process according to the second embodiment.
When the pulse width setting process is executed, the initial value of the pulse width of the repulsion pulse G1 (first pulse) of the reverse rotation signal is set to the maximum value within the changeable range.
When the pulse width setting process is started, the reverse rotation signal output unit 342 controls the drive circuit 40 to output a reverse rotation signal (S21).
Next, the rotation determination circuit 36 determines whether or not the reverse induced voltage generated in the coil 53 of the step motor 50 is reversed in the detection section, and determines whether or not the rotor 52 has rotated one step in the reverse direction. Determine (S22).

If YES is determined in S22, the pointer rotates by one step in the reverse direction from the initial position determined as the needle position at the time of factory shipment. Therefore, the normal rotation signal output unit 341 controls the drive circuit 40 to output a normal rotation signal (S23) and returns the pointer to the original position.
Next, in order to weaken the rotational force of the rotor 52 in the reverse rotation direction, the pulse width setting unit 343 sets the pulse width of the repulsion pulse G1 included in the reverse rotation signal to be shorter by a predetermined value (for example, 0.24 ms) ( S24). Then, the drive control circuit 34 returns the process to S21. That is, the processes of S21 to S24 are repeatedly executed until it is determined in S22 that the rotor 52 has not rotated one step in the reverse direction.

  When the rotation determination circuit 36 determines that the rotor 52 has not rotated one step in the reverse rotation direction (NO in S22), the pulse width setting unit 343 determines the pulse width of the repulsion pulse G1 included in the reverse rotation signal as follows: Set a predetermined value longer and confirm. That is, the pulse width setting unit 343 returns the pulse width of the repulsion pulse G1 to the value set once before and determines it (S25). Thereby, the pulse width of the repulsion pulse G1 can be set to a minimum value within a range in which the rotor 52 reliably rotates by one step in the reverse rotation direction. The set value of the pulse width of the repulsion pulse G1 is stored in a storage unit (not shown) of the motor control circuit 37. Then, the drive control circuit 34 ends the pulse width setting process.

[Effects of Second Embodiment]
Each time the rotation determination circuit 36 determines that the rotor 52 has rotated, the pulse width setting unit 343 decreases the pulse width of the repulsion pulse G1 by a predetermined value from the maximum value, and determines that the rotor 52 has not rotated. Then, the pulse width is increased by a predetermined value, and the setting of the pulse width is completed. For this reason, even when various types of pointers having different moments of inertia are mounted, the pulse width can be set to the minimum value within a range in which the rotor 52 reliably rotates by one step in the reverse rotation direction. Therefore, the step motor 50 can be reliably driven in the reverse direction, and power consumption for driving the step motor 50 can be reduced.
In addition, when the moment of inertia of the pointer is relatively large, the minimum value can be specified earlier compared to the case where the setting is performed by gradually shortening the pulse width of the first pulse from the minimum value, and the time required for the setting Can be shortened.
In addition, the same effects as those of the first embodiment can be obtained.

[Third Embodiment]
The electronic timepiece of the third embodiment differs from the first embodiment in the determination method by the rotation determination circuit 36. Other configurations are the same as those of the first embodiment.
10 is a diagram showing the same characteristics as FIG. 6, and FIG. 11 is a diagram showing the same characteristics as FIG.
If the rotor 52 cannot rotate in the reverse direction by one step by the reverse signal (especially, the repulsion pulse G1 as the first pulse and the suction pulse G2 as the second pulse), then the rotor 52 rotates in the normal direction. As shown, the difference D1 between the maximum value and the minimum value of the reverse induced voltage is relatively large.
Here, the maximum value of the reverse induced voltage is a value that maximizes the magnitude in the plus direction, and the minimum value is a value that minimizes the magnitude in the plus direction. That is, when the reverse induced voltage is negative, the value having the maximum magnitude in the negative direction is the minimum value.
For this reason, the rotation determination circuit 36 sets a predetermined period after the suction pulse G2 is output as a detection interval, and when the difference D1 in the detection interval is equal to or greater than a predetermined threshold, the rotor 52 is rotated by one step in the reverse direction. Judge that it did not rotate.
In addition, when the rotor 52 can be rotated by one step by the reverse rotation signal (particularly, the repulsion pulse G1 and the suction pulse G2), the rotor 52 does not rotate in the forward rotation direction thereafter, so that the difference D1 in the reverse induced voltage becomes relatively small.
For this reason, the rotation determination circuit 36 determines that the rotor 52 has rotated by one step in the reverse rotation direction when the difference D1 in the detection section is less than a predetermined threshold value.
Note that, instead of the reverse induced voltage, a reverse induced current is detected, and when the difference between the maximum value and the minimum value of the reverse induced current in the detection section is equal to or greater than a predetermined threshold value, the rotor 52 is rotated one step in the reverse direction. If the difference is less than a predetermined threshold value, it may be determined that the rotor 52 has rotated one step in the reverse direction.

[Effects of Third Embodiment]
The rotation determination circuit 36 determines that the rotor 52 has not rotated one step in the reverse direction when the difference D1 in the counter-induced voltage in the detection section of the counter-inductive voltage is equal to or greater than the predetermined threshold, and the difference D1 is the predetermined threshold. If it is less than this, it is determined that the rotor 52 has rotated one step in the reverse rotation direction, so that the rotation and non-rotation of the rotor 52 can be accurately determined.
Note that the same effect can be obtained when the determination is made based on the reverse induced current instead of the reverse induced voltage.

[Other Embodiments]
In addition, this invention is not limited to the structure of each said embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention.
For example, in each of the embodiments described above, the reverse rotation signal includes the repulsion pulse G1, the suction pulse G2, the repulsion pulse G3, and the attenuation pulse Gr. However, the present invention is not limited to this. For example, the repulsion pulse G3 and the attenuation pulse Gr may not be present.

  In each of the above embodiments, the pulse width setting process is performed at the time of factory shipment, but the present invention is not limited to this. For example, it may be performed when the user is using the electronic timepiece 1.

  In each of the above embodiments, the rotation determination circuit 36 determines the rotation of the rotor 52 based on the reverse induced voltage or the reverse induced current generated in the coil 53 of the step motor 50, but the present invention is not limited to this. . For example, the rotation of the rotor 52 may be determined using an optical sensor or the like that can detect whether or not the rotor 52 has rotated to a predetermined position.

  In each of the embodiments described above, the rotation determination circuit 36 uses the predetermined period immediately after the suction pulse G2 is output as the detection section, but the present invention is not limited to this. For example, a predetermined period immediately after the repulsion pulse G3 is output may be set as the detection section.

  In each of the embodiments described above, the electronic timepiece 1 is a wristwatch type, but may be a table clock, for example. The drive control device 30 may be mounted on an electronic device other than a watch.

  DESCRIPTION OF SYMBOLS 1 ... Electronic timepiece, 30 ... Drive control apparatus, 34 ... Drive control circuit, 341 ... Forward rotation signal output part, 342 ... Reverse rotation signal output part, 343 ... Pulse width setting part, 36 ... Rotation determination circuit, 37 ... Control circuit, 40 ... Drive circuit, 50 ... Step motor, 51 ... Stator, 52 ... Rotor, 53 ... Coil.

Claims (8)

A first pulse for rotating the step motor rotor in the forward rotation direction by controlling a drive circuit for driving the step motor; and a second pulse for rotating the rotor rotated in the forward rotation direction by the first pulse in the reverse rotation direction. A reverse signal output unit for outputting a reverse signal having a pulse;
A rotation determination unit that determines whether or not the rotor has rotated one step in the reverse rotation direction based on the reverse rotation signal;
A motor control circuit comprising: a pulse width setting unit that sets a pulse width of the first pulse based on a determination result of the rotation determination unit. The motor control circuit according to claim 1,
The pulse width of the first pulse is configured to be changeable within a preset range,
The pulse width setting unit includes:
An initial value of the pulse width of the first pulse is set to the minimum value of the range;
When the rotation determination unit determines that the rotor has not rotated, the pulse width of the first pulse is increased by a predetermined value,
When the rotation determination unit determines that the rotor has rotated, the setting of the pulse width is completed without changing the pulse width of the first pulse. The motor control circuit according to claim 1,
The pulse width of the first pulse is configured to be changeable within a preset range,
The pulse width setting unit includes:
An initial value of the pulse width of the first pulse is set to the maximum value of the range;
When the rotation determination unit determines that the rotor has rotated, the pulse width of the first pulse is shortened by a predetermined value,
When the rotation determination unit determines that the rotor has not rotated, the pulse width of the first pulse is increased by the predetermined value, and the setting of the pulse width is terminated. In the motor control circuit according to any one of claims 1 to 3,
The motor control circuit, wherein the rotation determination unit determines whether or not the rotor has rotated one step in the reverse direction based on a reverse induced voltage or a reverse induced current generated in the step motor. The motor control circuit according to claim 4,
The rotation determination unit determines that the rotor has rotated one step in the reverse direction when the reverse induced voltage or the reverse induced current is not reversed in a predetermined period after the second pulse is output. When the reverse induced voltage or the reverse induced current is reversed, it is determined that the rotor has not rotated by one step in the reverse direction. The motor control circuit according to claim 4,
When the difference between the maximum value and the minimum value of the reverse induced voltage or the reverse induced current in a predetermined period after the second pulse is output is less than a predetermined threshold, the rotation determining unit It is determined that the motor has rotated one step in the reverse direction, and when the predetermined threshold value is exceeded, it is determined that the rotor has not rotated one step in the reverse direction. The motor control circuit according to any one of claims 1 to 6,
The step motor;
An electronic timepiece comprising: a pointer driven by the step motor. A motor control method of a motor control circuit for controlling a step motor,
A first pulse for controlling the driving circuit for driving the step motor to rotate the rotor of the step motor in the forward rotation direction, and a first pulse for rotating the rotor rotated in the forward rotation direction by the first pulse in the reverse rotation direction. A reverse signal output step for outputting a reverse signal having two pulses;
A rotation determination step for determining whether or not the rotor has rotated by one step in the reverse rotation direction based on the reverse rotation signal;
A motor control method comprising: a pulse width setting step for setting a pulse width of the first pulse based on a determination result of the rotation determination step.

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