JP2014090589A - Stepping motor control circuit, movement and analog electronic timepiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent erroneous detection of a rotation situation or generation of erroneous rotation even in the case where a magnetic field is present.SOLUTION: A stepping motor control circuit comprises: a rotation detection section which detects a rotation situation of a stepping motor 107 by detecting an induction signal exceeding a reference threshold voltage generated in a detection resistor during a detection phase including a plurality of detection cycles each formed from a first time for forming a first closed circuit including a driving coil of the stepping motor 107 and the detection resistor for detecting an induction signal generated by the stepping motor 107, and a second time for forming a second closed circuit from a driving coil and a low impedance element; a magnetic field detection circuit 116 which detects a magnetic field; and a control section which selects a driving pulse on the basis of the rotation situation of the stepping motor 107 detected by the rotation detection section, and drives the stepping motor 107 in accordance with the selected driving pulse. The rotation detection section changes a length of the detection cycle in accordance with whether the magnetic field detection circuit 116 detects a magnetic field exceeding a predetermined intensity.

Description

  The present invention relates to a stepping motor control circuit, a movement including the stepping motor control circuit, and an analog electronic timepiece including the movement.

  Conventionally, when detecting rotation of a stepping motor in an analog electronic timepiece, in a detection section after driving the stepping motor, a closed circuit formed by a driving coil of the stepping motor and a low impedance element, the driving coil and the detection resistor By changing the time ratio (duty ratio) constituting the closed circuit including Rs, the detection accuracy of the induced signal VRs generated by the free vibration after the stepping motor rotates is increased, and highly accurate rotation detection is enabled. An invention has been developed (see, for example, Patent Document 1).

  Further, in Patent Document 2, based on the rotation detection method described in Patent Document 1, the detection signal VRs can be accurately detected by partially shortening the period of the detection pulse in the detection section. An invention is disclosed in which the free vibration of the stepping motor is not prolonged so as not to affect the correction drive pulse P2 drive after the passage of the detection section when the main drive pulse P1 does not rotate. Thereby, the rotation state of the stepping motor can be accurately detected, and when the stepping motor does not rotate, the stepping motor can be favorably rotated by the correction drive pulse P2.

  However, when a magnetic field exists outside the analog electronic timepiece, the rotor of the stepping motor is likely to rotate due to the influence of the magnetic field. In the rotation detection operation performed after the main drive pulse P1 is driven, a closed circuit including the detection resistor Rs and the drive coil is formed when the induced signal VRs is sampled, so that the braking force of the stepping motor is reduced. Therefore, there is a possibility that erroneous detection of the rotation state, or the rotor may erroneously cause 360 ° rotation (overrun: erroneous rotation), and erroneous movement may occur.

Japanese Patent Laid-Open No. 55-87977 JP 2009-288133 A

  The present invention has been made in view of the above problems, and it is an object of the present invention to suppress erroneous detection of rotation status and occurrence of erroneous rotation even when a magnetic field is present.

  According to a first aspect of the present invention, a first time for forming a closed circuit including a drive coil of a stepping motor and a detection element for detecting an induced signal generated by the stepping motor, the drive coil and a low impedance element In a detection section having a plurality of detection periods consisting of a second time for forming a closed circuit by detecting an induced signal exceeding a predetermined reference threshold voltage generated in the detection element, the rotation state of the stepping motor is determined. A rotation detection unit to detect, a magnetic field detection unit to detect a magnetic field, and a driving pulse is selected based on the rotation state of the stepping motor detected by the rotation detection unit, and the stepping motor is driven by the selected driving pulse. The rotation detection unit detects a magnetic field exceeding a predetermined intensity by the magnetic field detection unit. Depending on whether the stepping motor control circuit, characterized in that changing the detection period is provided.

  According to a second aspect of the present invention, there is provided a movement comprising the stepping motor control circuit.

  According to a third aspect of the present invention, there is provided an analog electronic timepiece comprising the movement.

According to the stepping motor control circuit of the present invention, it is possible to suppress erroneous detection of rotation status and occurrence of erroneous rotation even when a magnetic field is present.
In addition, according to the movement according to the present invention, it is possible to suppress erroneous detection of rotation status and occurrence of erroneous rotation even when a magnetic field is present.
Further, according to the analog electronic timepiece according to the invention, even when a magnetic field is present, it is possible to suppress erroneous detection of the rotation state and occurrence of erroneous rotation, so that accurate hand movement is possible.

It is a block diagram common to a stepping motor control circuit, a movement, and an analog electronic timepiece according to an embodiment of the present invention. It is a block diagram of the stepping motor used by embodiment of this invention. It is a partial detailed circuit diagram of an embodiment of the invention. It is a timing diagram of an embodiment of the invention. It is a timing diagram of an embodiment of the invention.

FIG. 1 is a block diagram relating to a stepping motor control circuit, a movement, and an analog electronic timepiece according to an embodiment of the present invention, and shows an example of an analog electronic wristwatch.
In FIG. 1, an analog electronic timepiece includes an oscillation circuit 101 that generates a signal of a predetermined frequency, a frequency dividing circuit 102 that divides the signal generated by the oscillation circuit 101 and generates a clock signal that serves as a time reference, and an analog electronic timepiece. Control circuit 103 for controlling each electronic circuit element constituting the control, control for changing the drive pulse (pulse control), etc., and main drive from the control circuit 103 among a plurality of types of main drive pulses P1 having different energy In response to the correction drive pulse control signal from the main drive pulse generation circuit 104 and the control circuit 103 for selecting and outputting the main drive pulse P1 corresponding to the pulse control signal, the correction drive pulse having a larger energy than the main drive pulse P1. A correction drive pulse generation circuit 105 that outputs P2 is provided.

The analog electronic timepiece includes a motor driver circuit 106 that drives the stepping motor 107 by the main drive pulse P1 and the correction drive pulse P2 from the main drive pulse generation circuit 104 and the correction drive pulse generation circuit 105, a stepping motor 107, and a watch case 109. It has.
Further, the analog electronic timepiece is disposed on the outer surface side of the timepiece case 109, and is an analog having a time hand (hour hand, minute hand, second hand) 112 that displays the time and date by being rotated by a stepping motor 107 and a calendar display unit 113. A display unit 108 and a movement 110 disposed inside the watch case 109 are provided.

  Further, the analog electronic timepiece sets a rotation detection circuit 114 for detecting an induced signal VRs generated by free vibration of the rotor of the stepping motor 107 and exceeding a predetermined reference threshold voltage Vcomp in a predetermined detection section T, and a detection pulse period. A detection pulse cycle selection circuit 115 and a magnetic field detection circuit 116 for detecting a magnetic field are included. The induced signal VRs is a signal representing the rotation state of the stepping motor 107.

  The rotation detection circuit 114 is configured to detect the induced signal VRs using the same principle as the rotation detection circuit described in Patent Document 1. The rotation detection circuit 114 includes a first time that forms a closed circuit (first closed circuit) including a drive coil of the stepping motor 107 and a detection element that detects the induced signal VRs generated by the stepping motor 107, and the drive coil The rotation state of the stepping motor 107 is detected in a detection section having a plurality of detection periods including a second time for forming a closed circuit (second closed circuit) with a low impedance element. The first time and the second time are alternately repeated, and the detection period is constituted by the first time and the second time, and the detection section is constituted by a plurality of detection periods.

When the rotation of the rotor is fast, such as when the stepping motor 107 rotates, an induced signal VRs exceeding a predetermined reference threshold voltage Vcomp is generated, and the rotor, such as when the stepping motor 107 does not rotate, is generated. The reference threshold voltage Vcomp is set so that the induced signal VRs does not exceed the reference threshold voltage Vcomp when the rotation operation is slow.
The detection pulse cycle selection circuit 115 controls the length of the detection cycle of the rotation detection circuit 114 to change depending on whether the magnetic field detection circuit 116 detects a magnetic field exceeding a predetermined intensity.

Oscillation circuit 101, frequency divider circuit 102, control circuit 103, main drive pulse generation circuit 104, correction drive pulse generation circuit 105, motor driver circuit 106, stepping motor 107, rotation detection circuit 114, detection pulse cycle selection circuit 115, magnetic field detection The circuit 116 is a component of the movement 110.
In general, a timepiece mechanical body composed of devices such as a timepiece power source and a time reference is called a movement. Electronic devices are sometimes called modules. When the watch is completed, a dial and hands are attached to the movement and housed in a watch case.

  Here, the oscillation circuit 101 and the frequency dividing circuit 102 constitute a signal generation unit, and the analog display unit 108 constitutes a display unit. The detection pulse cycle selection circuit 115 and the rotation detection circuit 114 constitute a rotation detection unit. The oscillation circuit 101, the frequency dividing circuit 102, the control circuit 103, the main drive pulse generation circuit 104, the correction drive pulse generation circuit 105, and the motor driver circuit 106 constitute a control unit. The control circuit 103 and the detection pulse cycle selection circuit 115 constitute a detection pulse cycle setting unit. In addition, the oscillation circuit 101, the frequency dividing circuit 102, the control circuit 103, the main drive pulse generation circuit 104, the correction drive pulse generation circuit 105, the motor driver circuit 106, the rotation detection circuit 114, the detection pulse cycle selection circuit 115, and the magnetic field detection circuit 116. Constitutes a stepping motor control circuit.

FIG. 2 is a configuration diagram of the stepping motor 107 used in the embodiment of the present invention, and shows an example of a timepiece stepping motor generally used in an analog electronic timepiece.
In FIG. 2, a stepping motor 107 includes a stator 201 having a rotor accommodating through hole 203, a rotor 202 rotatably disposed in the rotor accommodating through hole 203, a magnetic core 208 joined to the stator 201, and a winding around the magnetic core 208. A rotated drive coil 209 is provided. When the stepping motor 107 is used in an analog electronic timepiece, the stator 201 and the magnetic core 208 are fixed to a base plate (not shown) with screws (not shown) and joined to each other. The drive coil 209 has a first terminal OUT1 and a second terminal OUT2.

  The rotor 202 is magnetized to two poles (S pole and N pole). A plurality of (two in this embodiment) notch portions (outer notches) 206 and 207 are provided at positions facing each other across the rotor accommodating through hole 203 at the outer end portion of the stator 201 formed of a magnetic material. Is provided. Saturable portions 210 and 211 are provided between the outer notches 206 and 207 and the rotor accommodating through hole 203.

  The saturable portions 210 and 211 are configured so as not to be magnetically saturated by the magnetic flux of the rotor 202 but to be magnetically saturated when the drive coil 209 is excited to increase the magnetic resistance. The through hole 203 for accommodating the rotor has a circular hole shape in which a plurality of (two in the present embodiment) half-moon-shaped notches (inner notches) 204 and 205 are integrally formed at the opposing portion of the through hole having a circular outline. It is configured.

  The notches 204 and 205 constitute a positioning part for determining the stop position of the rotor 202. In a state in which the drive coil 209 is not excited, the rotor 202 is positioned corresponding to the positioning portion as shown in FIG. 2, in other words, the magnetic pole axis A of the rotor 202 is a line connecting the notches 204 and 205. It is stably stopped at a position orthogonal to the minute (position where the angle between the magnetic pole axis A and the X axis is θ0).

  Now, a drive pulse is supplied from the main drive pulse generation circuit 104 between the terminals OUT1 and OUT2 of the drive coil 209 (for example, the first terminal OUT1 side is positive and the second terminal OUT2 side is negative), and the direction of the arrow in FIG. When a current i is passed through the stator 201, a magnetic flux is generated in the stator 201 in the direction of the broken arrow. As a result, the saturable portions 210 and 211 are saturated and the magnetic resistance increases, and then the rotor 202 rotates 180 degrees in the direction of the arrow in FIG. 2 due to the interaction between the magnetic pole generated in the stator 201 and the magnetic pole of the rotor 202. Then, the magnetic pole axis A stops stably at the angle θ1 position. Incidentally, the rotation direction (counterclockwise direction in FIG. 2) for causing the normal operation (the hand movement operation because it is an analog electronic timepiece in this embodiment) by rotating the stepping motor 107 is the positive direction. The reverse (clockwise direction) is the reverse direction.

Next, a drive pulse having a reverse polarity is supplied from the main drive pulse generation circuit 104 to the terminals OUT1 and OUT2 of the drive coil 209 (the first terminal OUT1 side has a negative polarity and a first polarity so that the polarity is opposite to that of the drive). When the current flows in the opposite arrow direction in FIG. 2 when the current flows in the opposite arrow direction in FIG. Thereby, the saturable portions 210 and 211 are first saturated, and then the rotor 202 rotates 180 degrees in the same direction (positive direction) as described above due to the interaction between the magnetic pole generated in the stator 201 and the magnetic pole of the rotor 202. The magnetic pole axis A stably stops at the angle θ0 position.
Thereafter, by supplying signals with different polarities (alternating signals) to the drive coil 209 in this way, the above operation is repeated, and the rotor 202 can be continuously rotated 180 degrees in the direction of the arrow. It is configured to be able to.

FIG. 3 is a partial detailed circuit diagram of the embodiment of the present invention, and is a partial detailed circuit diagram of the main drive pulse generation circuit 104, the correction drive pulse generation circuit 105, the motor driver circuit 106, and the rotation detection circuit 114.
Although details of the operation will be described later, the switch control circuit 303 simultaneously turns on the transistors Q2 and Q3 in response to the control signal Vi supplied from the control circuit 103 during rotation driving, or the transistors Q1 and Q4 Are simultaneously turned on to supply drive current to the drive coil 209 in the forward or reverse direction, thereby driving the stepping motor 107 to rotate.

At the time of rotation detection, the transistors Q3 to Q6 are controlled to be in an on state, an off state, a switching state in which an on state and an off state (on / off state) are alternately repeated in a predetermined cycle, and the detection resistor 301 or In 302, control is performed so that the induced signal VRs based on the free vibration of the stepping motor 107 is generated.
When the induced signal VRs exceeding the predetermined reference threshold voltage Vcomp is generated in the detection resistor 301 or 302, the comparator 304 outputs the detection signal Vs at that time.

The transistors Q1 and Q2 are components of the motor driver circuit 106, and the transistors Q5 and Q6 and the detection resistors 301 and 302 are components of the rotation detection circuit 114. The transistors Q3 and Q4 are components that are used both as the motor driver circuit 106 and the rotation detection circuit 114.
The detection resistors 301 and 302 are elements having the same resistance value, and constitute detection elements. In addition, the detection resistors 301 and 302 are high impedance elements, and the transistors Q1 to Q6 form a low impedance element with a small on resistance in the on state.
The high impedance element has a higher impedance than drive coil 209, for example, several tens of ohms, and the low impedance element has a lower impedance than drive coil 209, for example, several tens of ohms.

  4 and 5 are timing diagrams according to the embodiment of the present invention. FIG. 4 is a timing diagram when a magnetic field exceeding a predetermined intensity does not exist outside the analog electronic timepiece. FIG. 5 is a predetermined timing outside the analog electronic timepiece. It is a timing diagram in case the magnetic field exceeding intensity | strength exists. The magnetic field may be either a DC magnetic field or an AC magnetic field. FIGS. 4 and 5 show the operation timing when rotating with one polarity, and the operation timing when rotating with the other polarity is omitted.

  When the stepping motor 107 is rotationally driven with the main drive pulse P1, the transistors Q2 and Q3 are switched and driven so as to be turned on / off at a predetermined period between times t1 and t2, which is a drive period, thereby providing a comb-shaped main A drive pulse P1 is generated, and a drive current i in the arrow direction is supplied to the drive coil 209 of the stepping motor 107 by the main drive pulse P1. Thereby, when the stepping motor 107 rotates, the rotor 202 rotates 180 degrees in the forward direction.

  On the other hand, a mask section IT is provided from time t2 to time t3 when the driving of the main drive pulse P1 is completed, and a detection section DT is provided from time t3 to time t4 following the mask section IT. The mask section IT is a period for preventing erroneous determination of the rotation state due to noise immediately after the main drive pulse P1 is driven, and the induced signal VRs generated during this period is not used as information for determining the rotation state. That is, the mask section IT is a period during which no rotation is detected. Note that the mask section IT is not necessary when it is not necessary to consider noise immediately after the driving of the stepping motor 107 is completed. In this case, the detection section DT is provided immediately after the main drive pulse P1 is driven.

The detection section DT includes a plurality of detection pulses repeated at a predetermined cycle (detection cycle). The detection cycle of each detection pulse is configured by a first time in which the detection resistor 301 or 302 is connected in series with the drive coil 209 and a second time in which the detection resistor 301 or 302 is not connected to the drive coil 209.
In the mask section IT and the detection section DT, the transistors Q1 to Q6 are driven in the same way. That is, in the mask period IT and the detection period DT, the transistor Q2 is driven to an off state, the transistors Q3 and Q6 are driven to an on state, and the transistor Q4 is driven to a switching state at a detection cycle.

  In this case, during the first time when the transistor Q4 is off, the detection resistor 302, the drive coil 209, and the low impedance transistors Q3 and Q6 form a closed circuit. That is, during the first time, a closed circuit (first closed circuit) including the detection resistor 302 that is a high impedance element and the drive coil 209 is configured. When the transistor Q4 is off, the induced signal VRs is detected by the detection resistor 302, and the braking force acting on the stepping motor 107 is small.

In addition, during the second time in which the transistor Q4 is on, the transistors Q3 and Q4 and the drive coil 209 form a closed circuit. That is, a closed circuit (second closed circuit) is constituted by the low impedance element and the drive coil 209 during the second time. When the transistor Q4 is in the ON state, the induced signal VRs is not detected by the detection resistor 302, and the braking force acting on the stepping motor 107 is large.
The detection cycle is changed according to the magnetic field intensity, and thereby control of detection sensitivity and braking force is performed.

The comparator 304 compares the induced signal VRs with a predetermined reference threshold voltage Vcomp, and outputs the detection signal Vs to the control circuit 103 when detecting the induced signal VRs exceeding the reference threshold voltage Vcomp.
When the rotor 202 rotates at a speed exceeding a predetermined speed, such as when the stepping motor 107 rotates, an induced signal VRs exceeding the reference threshold voltage Vcomp is generated, and when the stepping motor 107 cannot rotate, etc. The reference threshold voltage Vcomp is set so that the induced signal VRs exceeding the reference threshold voltage Vcomp is not generated when the motor rotates at a predetermined speed or less.

The control circuit 103 determines the rotation state of the stepping motor 107 based on the detection signal Vs, and performs pulse control such as pulse-up and pulse-down of the main drive pulse P1, and driving by the correction drive pulse P2.
After the above driving cycle is completed, the transistors Q1 to Q6 are driven and controlled so that the same operation is performed in the next driving cycle. That is, in the next driving cycle, the transistors Q1 and Q4 are switched to the on / off state in a predetermined cycle instead of the transistors Q2 and Q3, and the driving is performed by the comb-like main driving pulse P1.

In the mask period IT and the detection period DT, the transistor Q3 is switched and driven at the same timing as the transistor Q4 instead of the transistor Q4. Further, the transistor Q5 is driven to an on state instead of the transistor Q6.
The induced signal VRs generated by the rotation of the stepping motor 107 is generated in the detection resistor 301. When the comparator 304 detects the induced signal VRs exceeding the reference threshold voltage Vcomp, the comparator 304 outputs the detection signal Vs.

The control circuit 103 determines the rotation state of the stepping motor 107 based on the detection signal Vs, and performs pulse control such as pulse-up.
The rotation control of the stepping motor 107 is performed by alternately repeating the two driving cycles. If the stepping motor 107 does not rotate despite being driven by the main drive pulse P1, the correction drive pulse P2 is driven. In this case, the rotation detection operation is not performed.

Hereinafter, the operation of the embodiment of the present invention will be described with reference to FIGS.
First, an outline of the operation in a state where there is no magnetic field exceeding a predetermined intensity will be described.
The control circuit 103 counts the clock signal from the frequency dividing circuit 102 and outputs a main drive pulse control signal to the main drive pulse generation circuit 104 at a predetermined cycle. The main drive pulse generation circuit 104 outputs to the motor driver circuit 106 a main drive pulse P1 having energy corresponding to the main drive pulse control signal from among a plurality of types of main drive pulses P1 having different energy.

The motor driver circuit 106 drives the stepping motor 107 by the main drive pulse P1. The stepping motor 107 rotationally drives the time hand 112 and the calendar display unit 113. When the stepping motor 107 rotates normally, the time hand 112 is moved and the date display operation of the calendar display unit 113 is performed at a predetermined timing.
The rotation detection circuit 114 detects the induced signal VRs generated by the free vibration of the stepping motor 107 in the detection section DT after the mask section IT has elapsed after the end of driving by the main drive pulse P1. The rotation detection circuit 114 outputs a detection signal Vs indicating whether or not the induced signal VRs exceeding the predetermined reference threshold voltage Vcomp is detected to the control circuit 103.

  When the control circuit 103 determines that the induced signal VRs exceeding the reference threshold voltage Vcomp is not detected based on the detection signal Vs, the control circuit 103 outputs a correction drive pulse control signal to the correction drive pulse generation circuit 105. The correction drive pulse generation circuit 105 forcibly rotates the stepping motor 107 by the correction drive pulse P2 through the motor driver circuit 106.

In the next driving cycle, the control circuit 103 performs pulse control so that the main driving pulse P1 is changed to a main driving pulse P1 having an energy one rank higher (pulse-up). Further, when the main drive pulse having the same energy can be continuously driven a predetermined number of times, the pulse control is performed so that the main drive pulse P1 is changed to a main drive pulse having an energy smaller by one rank (pulse down). .
By repeating the above operation alternately for one polarity and the other polarity, the stepping motor 107 is continuously rotated, and the current time is displayed by the time hand 112 and the date is displayed by the calendar display unit 113.

  The operation will be further described with reference to FIGS. 3 and 4. The control circuit 103 counts the clock signal from the frequency dividing circuit 102, and at time t1, has one polarity (for example, the first terminal OUT1 side is the positive electrode, the first The control signal Vi is output to the main drive pulse generation circuit 104 so that the stepping motor 107 is driven by the main drive pulse P1 of the negative terminal on the 2 terminal OUT2 side.

The main drive pulse generation circuit 104 drives the stepping motor 107 with the main drive pulse P1 having energy corresponding to the control signal Vi (here, the first terminal OUT1 side is positive and the second terminal OUT2 side is negative). (FIG. 4A).
In this case, the switch control circuit 303 drives the stepping motor 107 with a comb-like main drive pulse P1 generated by switching the transistors Q2 and Q3 to the on / off state in response to the control signal Vi ( FIG. 4 (c), (d)).
When the stepping motor 107 is driven, an induced signal VRs corresponding to the rotation state is generated.

  In the detection period DT starting from time t3, the rotation detection circuit 114 detects the presence / absence of the induced signal VRs exceeding the reference threshold voltage Vcomp. In this rotation detection operation, the rotation detection circuit 114 turns on the transistors Q3 and Q6 (the same state as the mask section IT) and has a duty ratio that is set in advance by the detection pulse cycle selection circuit 115. The transistor Q4 is switched and driven between an on state and an off state by a detection pulse having a set period (FIGS. 4B, 4D, 4E, and 4F).

Here, since the magnetic field detection circuit 116 has not detected a magnetic field exceeding a predetermined intensity, the control circuit 103 controls the detection pulse cycle selection circuit 115 so as to set the switching drive cycle of the transistor Q4 to a predetermined first cycle. The detection pulse cycle control signal is output as described above.
In response to the detection pulse cycle control signal, the detection pulse cycle selection circuit 115 sets the switching cycle of the transistor Q4 to a predetermined first cycle without changing the duty ratio of the transistor Q4. Thereby, the ratio of the first time (T−t) for forming the first closed circuit and the second time t for forming the second closed circuit does not change, but the first time (T−t) and the second time The sum of t is the first detection period T. As will be described later, the first detection period is configured to be longer than the detection period (second detection period) when a magnetic field exceeding a predetermined intensity is detected.

  In this case, the detection cycle is longer than that in the case where a magnetic field exceeding a predetermined intensity exists, while the length of the detection section DT is fixed to a constant value, so that the second closed circuit is detected in the detection section DT. The number of times is formed is smaller than when a magnetic field exceeding a predetermined intensity exists. Therefore, since the braking of the stepping motor 107 is reduced, the detection sensitivity is increased, and good rotation detection is possible.

The induced signal VRs generated in the detection resistor 302 is compared with the reference threshold voltage Vcomp by the comparator 304 (FIG. 4 (g)). The comparator 304 outputs a detection signal Vs indicating whether or not the induced signal VRs exceeding the reference threshold voltage Vcomp is detected to the control circuit 103.
The control circuit 103 outputs a correction drive pulse control signal to the correction drive pulse generation circuit 105 when the detection signal Vs indicates that the induced signal VRs exceeding the reference threshold voltage Vcomp has not been detected. The correction drive pulse generation circuit 105 forcibly rotates the stepping motor 107 by the correction drive pulse P2 through the motor driver circuit 106.

  In the next driving cycle, the control circuit 103 performs pulse control so that the main driving pulse P1 is changed to a main driving pulse P1 having an energy one rank higher (pulse-up). When the main drive pulse P1 having the same energy can be continuously driven a predetermined number of times, the pulse control is performed so that the main drive pulse P1 is changed to a main drive pulse having a smaller energy (pulse down) and driven. Do.

At the time t1 of the next drive cycle, the control circuit 103 performs stepping with the main drive pulse P1 having the other polarity different from the one polarity (for example, the first terminal OUT1 side is negative and the second terminal OUT2 side is positive). A control signal Vi is output to the main drive pulse generation circuit 104 so as to drive the motor 107.
In response to the control signal Vi, the main drive pulse generation circuit 104 controls the stepping motor 107 with the main drive pulse P1 of the other polarity (here, the first terminal OUT1 side is negative and the second terminal OUT2 side is positive). To drive. In this case, the switch control circuit 303 drives the stepping motor 107 with the main drive pulse P1 generated by switching the transistors Q1 and Q4 in response to the control signal Vi.

When the stepping motor 107 is driven, an induced signal VRs corresponding to the rotation state is generated.
In the detection interval DT from time t3 to time t4 in the cycle, the rotation detection circuit 114 detects the induced signal VRs exceeding the reference threshold voltage Vcomp. At this time, the rotation detection circuit 114 switches the transistors Q4 and Q5 to the on state and switches the transistor Q3 between the on state and the off state at a predetermined cycle with the predetermined duty ratio.

At this time, the switching cycle and duty ratio of the transistor Q3 are the same as those of the transistor Q4 in the previous cycle.
The control circuit 103 determines the rotation state of the stepping motor 107 in the same manner as in the previous drive cycle, and performs a pulse control operation corresponding to the rotation state.
By repeating the above operation alternately for one polarity and the other polarity, the stepping motor 107 is continuously rotated to display the current time and date by the time hand 112.
When there is no magnetic field exceeding the predetermined intensity, the above operation is repeated.

On the other hand, when a magnetic field exists, the magnetic field detection circuit 116 detects the magnetic field and outputs a magnetic field detection signal representing the strength to the control circuit 103. Based on the magnetic field detection signal from the magnetic field detection circuit 116, the control circuit 103 determines whether or not there is a magnetic field exceeding a predetermined intensity.
When the control circuit 103 determines that there is a magnetic field exceeding a predetermined intensity based on the magnetic field detection signal from the magnetic field detection circuit 116, the duty ratio for switching the transistor Q4 is not changed when the rotation of the stepping motor 107 is detected. The control signal is changed so that the length of the switching period (in other words, the detection period T) is changed to the second detection period T shorter than the first detection period T when there is no magnetic field exceeding the predetermined intensity. It outputs to the detection pulse period selection circuit 115 (FIGS. 4 (e), (g), FIGS. 5 (e), (g)).

In response to the control signal from the control circuit 103, the detection pulse cycle selection circuit 115 sets the switching cycle of the transistor Q4 to a second time shorter than the first detection cycle T when there is no magnetic field exceeding the predetermined strength. The rotation detection circuit 114 is controlled to change to the detection cycle T.
That is, a first time (Tt) for forming a first closed circuit including the drive coil 209 of the stepping motor 107 and the detection resistor 301 or 302 for detecting the induced signal VRs generated by the stepping motor 107, and the drive coil 209 Depending on whether or not the magnetic field detection circuit 116 has detected a magnetic field exceeding a predetermined intensity in a detection section DT having a plurality of detection periods T consisting of a second time t forming a second closed circuit with a low impedance element. The detection period T is changed (here, when the magnetic field detection circuit 116 detects a magnetic field exceeding a predetermined intensity, the first time (T−t) and the second time are different from when the magnetic field exceeding the predetermined intensity is not detected. The detection cycle T is shortened without changing the time ratio of the time t.)

  In the present embodiment, the detection cycle is shortened compared to the case where there is no magnetic field exceeding the predetermined intensity, while the length of the detection section DT is fixed to a constant value. The number of times that the closed circuit is formed increases as compared with the case where there is no magnetic field exceeding a predetermined strength. Therefore, since braking is applied in small increments before the rotation speed of the rotor 202 increases, the braking effect is greater than when the detection period T is large.

  As described above, when there is a magnetic field exceeding a predetermined strength, rotation is easily caused by the influence of the magnetic field. However, since the number of times of braking is increased as compared with the case where a magnetic field exceeding the predetermined strength does not exist, the stepping motor 107 The braking becomes large and the occurrence of overrun can be suppressed. In addition, accurate rotation detection is possible, and it is possible to suppress erroneous detection of rotation conditions and generation of erroneous rotation.

  In addition, there is a possibility that the rotation detection capability may be reduced because braking increases in a magnetic field exceeding the predetermined strength. However, by appropriately selecting the detection period T, rotation detection equivalent to the case where there is no magnetic field exceeding the predetermined strength is possible. It can be configured to have capabilities. In addition, since the detection cycle T is short, the number of times the induced signal VRs is sampled increases, and the induced signal VRs that changes sharply can be detected without omission, so that highly accurate detection is possible.

Further, according to the movement 110 according to the embodiment of the present invention, it is possible to suppress erroneous detection of the rotation state and generation of erroneous rotation even when a magnetic field exceeding a predetermined intensity exists.
In addition, according to the analog electronic timepiece according to the embodiment of the present invention, it is possible to prevent erroneous detection of a rotation situation and generation of erroneous rotation even when a magnetic field exceeding a predetermined intensity exists. There is an effect that the hand movement becomes possible.

  As described above, the stepping motor control circuit according to the embodiment of the present invention includes the drive coil 209 of the stepping motor 107 and the detection resistor 301 or 302 as a detection element that detects the induced signal VRs generated by the stepping motor 107. Detection having a plurality of detection periods T including a first time for forming a closed circuit (first closed circuit) including a second time for forming a closed circuit (second closed circuit) by the drive coil 209 and the low impedance element In a section DT, a rotation detection unit that detects a rotation state of the stepping motor 107 by detecting an induced signal VRs exceeding a predetermined reference threshold voltage Vcomp generated in the detection element, and a magnetic field detection circuit 116 that detects a magnetic field. Based on the rotation state of the stepping motor 107 detected by the rotation detector, the drive pulse And a control unit that drives the stepping motor 107 by the selected drive pulse, the rotation detection unit according to whether or not the magnetic field detection circuit 116 has detected a magnetic field exceeding a predetermined intensity, It is characterized by changing the length of the detection cycle T.

Here, the rotation detection unit can be configured such that when the magnetic field detection circuit 116 detects a magnetic field exceeding a predetermined intensity, the detection cycle T is made shorter than when a magnetic field exceeding the predetermined intensity is not detected.
In addition, the rotation detection unit can be configured such that when the magnetic field detection circuit 116 does not detect a magnetic field exceeding a predetermined intensity, the detection cycle T is made longer than when a magnetic field exceeding the predetermined intensity is detected.

Therefore, even when a magnetic field exceeding a predetermined intensity exists, it is possible to suppress erroneous detection of the rotation state and erroneous rotation.
In addition, since the movement according to the embodiment of the present invention is characterized by including the stepping motor control circuit, even if a magnetic field exceeding a predetermined intensity exists, erroneous detection of a rotation state or erroneous rotation is detected. It is possible to suppress the occurrence.
In addition, according to the analog electronic timepiece according to the embodiment of the present invention, it is possible to prevent erroneous detection of a rotation situation and generation of erroneous rotation even when a magnetic field exceeding a predetermined intensity exists. Hand movement becomes possible.

In the present embodiment, the detection period can be set to two types of the first detection period and the second detection period depending on whether or not a magnetic field exceeding a predetermined intensity exists. Depending on the size, it may be changed to two or more types, or may be changed in an analog manner.
Further, the drive pulse may be a rectangular wave-like drive pulse in addition to the comb-like drive pulse.
In the present embodiment, the detection interval DT is configured by one interval. However, the detection interval DT is divided into a plurality of intervals, and the stepping motor is determined according to the pattern of the interval in which the induced signal VRs exceeding the reference threshold voltage Vcomp is detected. The rotation state may be detected.

The stepping motor control circuit according to the present invention is applicable to various electronic devices that use the stepping motor.
The movement according to the present invention is applicable to movements used in various analog electronic timepieces such as analog electronic wristwatches and analog electronic table clocks.
The analog electronic timepiece according to the present invention is applicable to various analog electronic timepieces such as an analog electronic wristwatch and an analog electronic table clock.

DESCRIPTION OF SYMBOLS 101 ... Oscillation circuit 102 ... Frequency dividing circuit 103 ... Control circuit 104 ... Main drive pulse generation circuit 105 ... Correction drive pulse generation circuit 106 ... Motor driver circuit 107 ... Stepping motor 108 ... analog display 109 ... watch case 110 ... movement 112 ... time hand 113 ... calendar display 114 ... rotation detection circuit 115 ... detection pulse cycle selection circuit 116 ... Magnetic field detection circuit 201... Stator 202... Rotor 203... Rotor housing through-holes 204 and 205.
206, 207 ... Notch (outer notch)
208 ... Magnetic core 209 ... Drive coils 210, 211 ... Saturable parts 301, 302 ... Detection resistor 303 ... Switch control circuit 304 ... Comparator OUT1 ... First terminal OUT2 ...・ Second terminal

Claims (6)

A first circuit for forming a closed circuit including a drive coil of a stepping motor and a detection element for detecting an induced signal generated by the stepping motor to detect the induced signal, and a closed circuit by the drive coil and a low impedance element In a detection section having a plurality of detection periods consisting of a second time for braking the stepping motor without detecting the induced signal by forming
A rotation detection unit that detects a rotation state of the stepping motor by detecting an induced signal exceeding a predetermined reference threshold voltage generated in the detection element;
A magnetic field detector for detecting the magnetic field;
A drive pulse is selected based on the rotation state of the stepping motor detected by the rotation detection unit, and the control unit drives the stepping motor with the selected drive pulse.
The stepping motor control circuit, wherein the rotation detection unit changes the detection cycle depending on whether the magnetic field detection unit detects a magnetic field exceeding a predetermined intensity.   2. The stepping according to claim 1, wherein the rotation detection unit shortens the detection cycle when the magnetic field detection unit detects a magnetic field exceeding a predetermined intensity, compared with a case where the magnetic field exceeding the predetermined intensity is not detected. Motor control circuit.   2. The stepping according to claim 1, wherein when the magnetic field detection unit does not detect a magnetic field exceeding a predetermined strength, the rotation detection unit makes the detection cycle longer than when detecting a magnetic field exceeding the predetermined strength. Motor control circuit.   The stepping motor control circuit according to claim 1, wherein the detection element has a higher impedance than the low impedance element.   A movement comprising the stepping motor control circuit according to any one of claims 1 to 4.   An analog electronic timepiece comprising the movement according to claim 5.

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