JP7460511B2 - step motor drive device - Google Patents

Description

The present invention relates to a step motor drive device for driving a two-coil step motor.

In two-coil step motors used in analog display electronic watches, a technique is known that switches between a drive pulse that excites both coils simultaneously and a drive pulse that excites only one of the coils.

For example, the invention described in Patent Document 1 proposes an electronic watch equipped with a two-coil step motor capable of high-speed operation. To rotate the rotor 360 degrees, a method is adopted in which a drive pulse that excites only one coil rotates it 135 degrees, and a drive pulse that excites both coils simultaneously rotates it 225 degrees. This allows the rotor to rotate once in a short time without stopping, realizing high-speed operation and smooth hand movement, and it is shown that an electronic watch with a good appearance can be provided.

International Publication No. 2017/141994

Multi-functional electronic watches have a world time display mode in addition to the current time display mode, and when switching between modes, there is a need for the hands to move more quickly.

An object of the present invention is to provide a step motor drive device that allows a two-coil step motor to be driven more quickly.

In order to achieve the above object, there is provided a step motor drive device for driving a step motor having a rotor magnetized with two or more poles in the radial direction, a stator having a first stator magnetic pole portion and a second stator magnetic pole portion provided opposite the rotor, and a third stator magnetic pole portion provided between the first and second stator magnetic pole portions facing the rotor, a first coil magnetically coupled to the first stator magnetic pole portion and the third stator magnetic pole portion, and a second coil magnetically coupled to the second stator magnetic pole portion and the third stator magnetic pole portion,
a drive voltage generating means capable of generating a first drive voltage which is applied to the first coil and the second coil and excites the first stator magnetic pole portion and the second stator magnetic pole portion with polarities different from each other, and a second drive voltage which is applied to either the first coil or the second coil and excites the first stator magnetic pole portion and the second stator magnetic pole portion with polarities different from each other and excites the third stator magnetic pole portion with the same polarity as the first stator magnetic pole portion or the second stator magnetic pole portion;
A step motor drive device is provided in which a drive voltage generating means rotates the rotor by 90 degrees or more with a first drive voltage, rotates the rotor by 180 degrees with the first drive voltage and the second drive voltage, and drives the rotor to rotate by alternately and repeatedly applying the first drive voltage and the second drive voltage.

The step motor drive device preferably rotates the rotor by more than 115 degrees and less than 150 degrees using the first drive voltage.

The above-mentioned step motor drive device further includes a steering storage means for storing the polarity value of the rotor, the steering storage means inverts the polarity value after outputting the second drive voltage, and the drive voltage generation means stores the polarity value based on the polarity value. , the first drive voltage, and the second drive voltage are preferably applied in opposite directions.

The above-mentioned step motor drive device includes a detection pulse generating means capable of generating a detection pulse for detecting rotation of the rotor, and a detection pulse generator that applies a voltage based on the detection pulse to the first coil or the second coil. It is preferable that the rotor further includes rotation detection means for determining rotation/non-rotation of the rotor based on a detection signal generated by the rotor.

It is preferable that the step motor drive device described above has a variable time for applying the second drive voltage to the step motor, the rotation detection means detects the rotation of the rotor while the second drive voltage is being applied, and the application time width of the second drive voltage being applied is variable based on the detection result of the rotation detection means.

It is preferable that the step motor drive device described above is variable in the time for which the first drive voltage is applied to the step motor, and that the application time of the next application of the first drive voltage is variable based on the detection result of the rotation detection means.

The step motor drive device described above further includes a correction pulse generating means capable of generating a correction pulse to assist rotation of the rotor, and the correction pulse generating means generates a correction pulse when the rotation detecting means determines that the rotor is not rotating. Preferably, a corresponding voltage is output to the step motor following the second drive voltage.

The step motor drive device further includes a terminal pulse generating means capable of generating a terminal pulse that stops the rotation of the rotor, and it is preferable that the terminal pulse generating means outputs a voltage corresponding to the terminal pulse to the step motor after outputting the first drive voltage or the second drive voltage when driving is stopped.

The step motor drive device further includes an initial pulse generating means capable of generating an initial pulse that assists the rotor in starting to move from a stopped state, and the initial pulse generating means preferably outputs a voltage corresponding to the initial pulse to the step motor before outputting the first drive voltage when driving starts.

The step motor drive device preferably has a variable time for applying a voltage corresponding to the initial pulse to the step motor, a rotation detection means detects the rotation of the rotor while the initial pulse is being applied, and the time for applying a voltage corresponding to the initial pulse to the step motor is variable based on the detection result of the rotation detection means.

By increasing the ratio of the output period of the drive pulse that simultaneously excites two coils compared to the output period of the drive pulse that excites only one coil, it has become possible to provide a step motor drive device that can drive a two-coil step motor at higher speeds than before.

FIG. 1 is a plan view showing an example of an electronic timepiece 10. 1 is a schematic configuration diagram of a step motor drive device 20 according to a first embodiment of the present invention. FIG. 1 is a schematic diagram of a two-coil step motor. FIG. 2 is a circuit diagram showing an example of a driver circuit 30. 13A shows an example of drive waveforms O1 to O4 produced by a drive pulse train SP10, and FIG. 13B is a table showing the operation of each transistor by the drive pulse train SP10. 11A to 11E are diagrams illustrating the operation of the step motor 40 in response to the drive pulse train SP10. 13A shows an example of drive waveforms O1' to O4' produced by a reverse rotation drive pulse train SP10', and FIGS. 13B to 13F show the operation of the step motor 40 produced by the reverse rotation drive pulse train SP10'. (a) shows a drive waveform shown as a comparative example, and (b) to (e) are operation diagrams of the step motor 40 with drive waveforms shown as a comparative example. 9 is a diagram for explaining a comparison between the drive waveform produced by the drive pulse train SP10 shown in FIG. 5 and the drive waveform produced by the drive pulse train SP20 shown in FIG. 8 as a comparative example. FIG. 7 is a diagram showing the time difference between the drive pulse train SP10 and the drive pulse train SP20 when the angle at which the rotor is rotated is changed by the first drive voltage in the step motor drive device 20, and (a) is the angle at which the rotor is rotated. (b) shows the case where the angle of rotation of the rotor is 135 degrees, and (c) shows the case where the angle of rotation of the rotor is 150 degrees. FIG. 11 is a schematic diagram of a step motor drive device 50 according to a second embodiment of the present invention. FIG. 2 is a circuit diagram showing an example of a driver circuit 60. 5 is a diagram for explaining rotation and non-rotation of a rotor 41 of a step motor 40. FIG. 13A shows an example of drive waveforms O1 to O4 generated by a drive pulse train SP30, and FIG. 13B is a table showing the operation of each transistor by the drive pulse train SP30 and a detection pulse CP. 5 is a diagram showing an example of a pulse waveform output from a drive pulse generation circuit 53. FIG. (a) shows an example of drive waveforms О1 to О4 corresponding to the drive pulse train SP30 when the correction pulse FP is included, and (b) is a table showing the ON/OFF states of the transistors of the driver circuit 60 according to the correction pulse FP. be. 5A to 5F are diagrams for explaining the operation of the step motor 40 in response to the correction pulse FP. FIG. 5 is an operation flow diagram of a step motor drive device 50 according to a second embodiment. (a) is a diagram showing the waveform of the induced current generated in coil A, (b) is a diagram showing the waveform of the induced current generated in coil B, and (c) is a diagram showing an example of drive waveforms O1 to O4 applied to coil terminals O1 to O4. 13A to 13C are diagrams illustrating a modification of the second embodiment of the present invention. It is a schematic block diagram of the step motor drive device 70 based on the 3rd Embodiment of this invention. 13A shows an example of drive waveforms O1 to O4 corresponding to an initial action pulse train IP10, and FIG. 13B is a table showing the ON/OFF states of the transistors of the driver circuit 60 by the initial action pulse train IP10 and the detection pulse CP. (a) to (d) are diagrams for explaining the operation of the step motor 40 based on the initial pulse train IP10. 13A shows an example of drive waveforms O1 to O4 corresponding to the drive pulse train SP30 and the terminal pulse train EP, and FIG. 13B is a table showing the ON/OFF state of the transistors of the driver circuit 60 by the terminal pulse train EP. 11A to 11D are diagrams for explaining the operation of the step motor 40 by the terminal pulse EP. (a) to (d) are diagrams for explaining a first modification of the third embodiment of the present invention. (a) and (b) are diagrams for explaining a second modification of the third embodiment of the present invention. It is an operation flow diagram in modification 2 of a 3rd embodiment.

Various embodiments of the present invention will be described below with reference to the drawings. However, please note that the technical scope of the present invention is not limited to these embodiments, but extends to the inventions described in the claims and their equivalents.

[First embodiment]
FIG. 1 is a plan view showing an example of an electronic timepiece 10 to which a step motor drive device 20 according to the present invention can be applied, and FIG. 2 is a schematic configuration diagram of the step motor drive device 20 according to the first embodiment of the present invention. It is.

The electronic timepiece 10 shown in FIG. 1 is an electronic timepiece of an analog display type, and includes a dial 11, an hour hand 12a, a minute hand 12b, a second hand 12c, a step motor drive device 20 shown in FIG. 2, and a two-coil step shown in FIG. It has a motor 40 and the like. Although not shown, the electronic timepiece 10 further includes a wheel train, a rotary weight for rotationally driving to generate vibrations, a power source, and the like. The step motor 40 is mechanically connected to a wheel train for driving a pointer and a rotating weight. The wheel train is configured so that three hands, an hour hand 12a, a minute hand 12b, and a second hand 12c, are interlocked. Further, the wheel train is configured to be able to mechanically select whether to drive the pointer or the rotating weight, and one step motor 40 can drive both the pointer and the rotating weight. The power source includes, for example, a secondary battery.

The step motor drive device 20 includes an oscillation circuit 21, a control circuit 22, a drive pulse generation circuit 23, and a driver circuit 30. The step motor drive device 20 is implemented, for example, as an integrated circuit including a microprocessor. The oscillation circuit 21 generates a predetermined clock signal P1 using a crystal resonator (not shown) and outputs it to the control circuit 22. The control circuit 22 generates a control signal CN1 based on the clock signal P1 and outputs it to the drive pulse generation circuit 23. The drive pulse generation circuit 23 generates a drive pulse train SP10 based on the control signal CN1 and outputs it to the driver circuit 30. The driver circuit 30 generates drive waveforms O1 to O4 based on the drive pulse train SP10 and supplies them to the step motor 40.

FIG. 3 is a schematic configuration diagram of a two-coil step motor that can be driven by the two-coil step motor drive device according to the present invention. As shown in FIG. 3, the step motor 40 includes a rotor 41, a stator 42, two coils (coil A and coil B), and the like.

The rotor 41 is a two-pole magnetized disk-shaped rotating body, with a north pole and a south pole magnetized in the radial direction. The rotor shaft 43 is provided at the center of the rotor 41, and rotatably supports the rotor 41 by bearings (not shown) provided above and below in the vertical direction of the drawing.

The stator 42 is made of a soft magnetic material, and has a rotor hole 44 into which the rotor 41 is inserted, and the rotor 41 is disposed in the rotor hole 44. The stator 42 has a first stator magnetic pole portion 45a (hereinafter abbreviated as "first magnetic pole portion 45a") and a second stator magnetic pole portion 45b (hereinafter abbreviated as "second magnetic pole portion 45b") that are substantially opposite the rotor 41. In addition, a third stator magnetic pole portion 45c (hereinafter abbreviated as "third magnetic pole portion 45c") is provided between the first magnetic pole portion 45a and the second magnetic pole portion 45b, facing the rotor 41.

Between the first magnetic pole portion 45a and the second magnetic pole portion 45b, which are opposite the third magnetic pole portion 45c across the rotor 41, a narrowed portion 46 is provided where the width of the stator is narrowed. Also, when viewed from the center of the rotor 41, if the direction of the third magnetic pole portion 45c is 0 degrees, a slit 47 is provided at a position approximately 75 degrees to the left and right. In other words, the first magnetic pole portion 45a and the third magnetic pole portion 45c, the second magnetic pole portion 45b and the third magnetic pole portion 45c, and the first magnetic pole portion 45a and the second magnetic pole portion 45b are difficult to magnetically connect. The narrowed portion 46 and the slit 47 may be a narrowed portion or a gap as shown here, or a narrow non-magnetic material may be inserted at the position of the slit 47 and connected to the stator.

The step motor 40 includes a coil A as a first coil that is magnetically coupled to a first magnetic pole section 45a and a third magnetic pole section 45c, and a coil A that is magnetically coupled to a second magnetic pole section 45b and a third magnetic pole section 45c. A coil B is provided as a second coil.

Both ends of the coil winding of the coil A are connected to coil terminals O1 and O2 arranged on the insulating substrate 48a, respectively. Further, the coil B has coil terminals O3 and O4 on the insulating substrate 48b, and both ends of the winding of the coil B are connected. Drive waveforms O1 to O4 output from the driver circuit 30 described above are supplied to each of the coil terminals O1 to O4, respectively. In order to make the explanation easier to understand, each coil terminal and each supplied drive waveform are given the same reference numerals. Further, as an example, the coil terminal O1 is the beginning of winding of the coil A, and the coil terminal O4 is the beginning of winding of the coil B. As shown in FIG. 3, the coil A is wired to the insulating substrate 48a, the coil B is wired to the insulating substrate 48b, and the insulating substrates 48a and 48b are fixed to the stator 48 with three screws 49.

The rotor 41 shown in FIG. 3 is in a stationary state, and the top of the drawing is defined as 0 degrees (starting point), and 90 degrees, 180 degrees, and 270 degrees are defined counterclockwise from that position. The rotor 41 has a statically stable point when the N pole is at 0 degrees and when it is at 180 degrees. When the stator 42 is not magnetized, a force acts on the rotor 41 to keep it at the statically stable point due to the holding torque. Note that the rotor 41 shown in FIG. 3 has the N pole at the statically stable point of 0 degrees. In order to make it easier to understand the explanation of the rotation drive of the step motor 40 described later, the start position of steady rotation is defined as when the N pole of the rotor 41 is at 135 degrees. By the way, when the stator 42 is not magnetized, the N pole of the rotor 41 cannot be positioned at the start position of steady rotation, but a method of aligning the N pole of the rotor 41 with the start position of steady rotation and then driving it steadily will be described in the third embodiment described later. The starting position of steady-state rotation can be any position as long as the north pole of the rotor 41 is between 90 degrees and 180 degrees, and can usually be adjusted as desired by the design of the stator 42.

Figure 4 is a circuit diagram showing an example of a driver circuit 30.

As shown in FIG. 4, the driver circuit 30 includes four buffer circuits that supply drive waveforms O1 to O4 to the coil A and coil B of the step motor 40 based on the drive pulse train SP10.

In the first buffer circuit, transistor P1, a P-channel MOS transistor with low on-resistance, and transistor N1, an N-channel MOS transistor with low on-resistance, are complementary connected to generate a drive waveform O1 and supply it to coil terminal O1 of coil A. In the second buffer circuit, transistor P2, a P-channel MOS transistor with low on-resistance, and transistor N2, an N-channel MOS transistor with low on-resistance, are complementary connected to generate a drive waveform O2 and supply it to coil terminal O2 of coil A.

In the third buffer circuit, transistor P3, a P-channel MOS transistor with low on-resistance, and transistor N3, an N-channel MOS transistor with low on-resistance, are complementary connected to generate a drive waveform O3 and supply it to coil terminal O3 of coil B. In the fourth buffer circuit, transistor P4, a P-channel MOS transistor with low on-resistance, and transistor N4, an N-channel MOS transistor with low on-resistance, are complementary connected to generate a drive waveform O4 and supply it to coil terminal O4 of coil B.

A drive pulse is input from the drive pulse generation circuit 23 to the gate terminal G of each transistor P1 to P4 and N1 to N4, and each transistor is ON/OFF controlled based on the drive pulse to generate drive waveforms O1 to O4. Output.

FIG. 5(a) shows an example of the drive waveform and O1 to O4 by the drive pulse train SP10, and FIG. 5(b) is a table showing the operation of each transistor by the drive pulse train SP10.

Figure 5 (a) shows four drive waveforms O1 to O4 output from the driver circuit 30 to coil terminals O1 to O4 in order to rotate the rotor 41 in the forward direction (counterclockwise) from a state in which the N pole is at 135 degrees, the starting position of steady rotation.

Figure 5 (b) is a table showing the ON/OFF states of the eight transistors P1-P4 and N1-N4 of the driver circuit 30 to generate the drive waveforms O1-O4. As described later, the drive waveforms O1-O4 are also divided into four states according to the four drive states of the step motor 40, and the first drive pulse SP11 determines the ON/OFF state of the eight transistors of the driver circuit 30 to be in the first state. Similarly, the second drive pulse SP12 determines the ON/OFF state of the eight transistors of the driver circuit 30 to be in the second state, the third drive pulse SP13 determines the ON/OFF state of the eight transistors of the driver circuit 30 to be in the third state, and the fourth drive pulse SP14 determines the ON/OFF state of the eight transistors of the driver circuit 30 to be in the fourth state. Additionally, the first drive pulse SP11 to the fourth drive pulse SP14 are collectively referred to as the drive pulse train SP10.

As shown in FIG. 5(a), the drive pulse train SP10 includes four drive pulses: a first drive pulse SP11, a second drive pulse SP12, an inverted first drive pulse SP13 obtained by inverting the direction of application of the first drive pulse SP11 to the coil, and an inverted second drive pulse SP14 obtained by inverting the direction of application of the second drive pulse SP12 to the coil. When the step motor 40 continues to rotate, the four drive waveforms O1 to O4 shown in FIG. 5(a) are repeatedly and sequentially supplied to the step motor 40, so that the drive pulse train SP10 is repeatedly and sequentially output to the driver circuit 30.

The control circuit 22 includes a steering storage means (not shown) that stores the polarity of the rotor 41, and the steering storage means stores a variable that stores the direction of applying pulses to the coil. Further, the value of the variable is inverted every time the second drive pulse SP12 and the inverted second drive pulse SP14 are output. The control circuit 22 generates a first drive pulse SP11, a second drive pulse SP12, an inverted third drive pulse SP13, and an inverted fourth drive pulse SP14 from the drive pulse generation circuit 23 based on the value of the variable. Control to enable selective output. As a result, the direction of current application to each coil is reversed.

The voltage of the drive waveforms O1 and O3 by the first drive pulse SP11 is 0 (v), and the voltage of the drive waveforms O2 and O4 is -V (v). This causes a drive current to flow through both coils A and B of the step motor 40, exciting both coils A and B.

The voltage of the drive waveform O4 by the second drive pulse SP12 is -V (v), and the voltages of the other drive waveforms O1, O2, and O3 are 0 (v). As a result, a drive current flows only through coil B of the step motor 40, and only coil B is excited. In this case, no drive current flows through coil A.

The four drive waveforms O1 to O4 generated by the third drive pulse SP13 are inverted voltage states of the four drive waveforms O1 to O4 generated by the first drive pulse SP11. That is, the voltage of the drive waveforms O2 and O4 by the third drive pulse SP13 is 0 (v), and the voltage of the drive waveforms O1 and O3 is -V (v). As a result, a drive current flows in both coil A and coil B of the step motor 40 in the opposite direction to that of the drive waveforms O1 to O4 caused by the first drive pulse SP11, and both coils A and B move in the opposite direction. It is excited in the direction.

The voltages of the drive waveforms O1, O2, and O4 by the fourth drive pulse SP14 are 0 (v), and the voltage of the drive waveform O3 is -V (v). As a result, a drive current flows through the coil B of the step motor 40 in a direction opposite to that of the drive waveforms O1 to O4 caused by the second drive pulse SP12, and only the coil B is excited in the opposite direction.

Note that the period of the drive pulse train SP10, that is, the total pulse width is arbitrary. Furthermore, although the drive waveforms O1 to O4 are illustrated as continuous full pulses, they may also be chopper-type drive pulses made up of a plurality of fine pulse groups.

Figure 6 is a diagram showing the operation of the step motor 40 using the drive waveforms and O1 to O4 shown in Figure 5. The rotational drive of the step motor 40 in the forward direction (counterclockwise) will be explained using Figures 6 (a) to (e).

As shown in FIG. 6A, the starting position of the north pole of the rotor 41 is assumed to be 135 degrees counterclockwise from the 0 degree position shown in FIG. Note that in FIG. 6, the amount of movement of the rotor 41 due to each pulse is shown as an example, and can normally be arbitrarily adjusted depending on the design of the stator 42.

FIG. 6(b) shows a state in which voltages shown in drive waveforms O1 to O4 by the first drive pulse SP11 are supplied to coil terminals O1 to O4 of the step motor 40, and coils A and B are Drive current flows through both, and both coils A and B are excited in the directions of the arrows. As a result, the first magnetic pole part 45a is magnetized to the north pole, the second magnetic pole part 45b is magnetized to the south pole, and the third magnetic pole part 45c is not magnetized because the magnetization cancels each other out. As a result, the N pole of the rotor 41 and the S pole of the second magnetic pole part 45b attract each other, and the S pole of the rotor 41 and the N pole of the first magnetic pole part 45a attract each other, and the N pole of the rotor 41 moves counterclockwise. It rotates approximately 135 degrees from the steady rotation starting position of 135 degrees to a position of 270 degrees.

Next, FIG. 6(c) shows the state in which the voltages shown in the drive waveforms O1 to O4 by the second drive pulse SP12 are supplied to the coil terminals O1 to O4 of the step motor 40, and drive current flows only through coil B, so that only coil B is excited in the direction of the arrow. As a result, the second magnetic pole portion 45b is magnetized as an S pole and the third magnetic pole portion 45c is magnetized as an N pole, and since coil A is not excited, the first magnetic pole portion 45a becomes the same N pole as the third magnetic pole portion 45c. As a result, the S pole of the row 41 and the N poles of the first magnetic pole portion 45a and the third magnetic pole portion 45c attract each other, and the N pole of the rotor 41 continues to rotate counterclockwise without stopping, rotating approximately 45 degrees from the 270 degree position to the 315 degree position.

At this point, the rotor 41 has been rotated 180 degrees counterclockwise from the steady rotation start position by the voltages shown in the drive waveforms O1 to O4 caused by the first drive pulse SP11 and the second drive pulse SP12. become.

Next, Figure 6(d) shows the state in which the voltages shown in the four drive waveforms O1 to O4 by the third drive pulse SP13 (voltages in which the voltage states of the four drive waveforms O1 to O4 by the first drive pulse SP11 are inverted) are supplied to coil terminals O1 to O4. As a result, a drive current flows in both coils A and B in the opposite direction to that in the drive waveforms O1 to O4 by the first drive pulse SP11, and both coils A and B are excited in the direction of the arrow (the opposite direction to that in Figure 6(b)). As a result, the first magnetic pole portion 45a is magnetized to the S pole, the second magnetic pole portion 45b is magnetized to the N pole, and the magnetizations of the third magnetic pole portion 45c cancel each other out and are not magnetized. As a result, the north pole of the rotor 41 and the south pole of the first magnetic pole portion 45a attract each other, and the south pole of the rotor 41 and the north pole of the second magnetic pole portion 45b attract each other, and the north pole of the rotor 41 rotates counterclockwise, rotating approximately 45 degrees from the 315 degree position, passing through the 0 degree position, to the 90 degree position.

Next, FIG. 6(e) shows the state in which the voltages shown in the drive waveforms O1 to O4 by the fourth drive pulse SP14 are supplied to the coil terminals O1 to O4 of the step motor 40. As a result, a drive current flows through coil B in the opposite direction to that of the drive waveforms O1 to O4 by the second drive pulse SP12, and only coil B is excited in the direction of the arrow (opposite direction from FIG. 6(c)). As a result, the second magnetic pole portion 45b is magnetized to the N pole, the third magnetic pole portion 45c is magnetized to the S pole, and since coil A is not excited, the first magnetic pole portion 45a becomes the same S pole as the third magnetic pole portion 45c. As a result, the N pole of the rotor 41 and the S poles of the first magnetic pole portion 45a and the third magnetic pole portion 45c attract each other, and the N pole of the rotor 41 further rotates counterclockwise without stopping, rotating about 45 degrees from the 90 degree position to the 135 degree position, which is the start position of steady rotation.

At this point, the rotor 41 is driven to rotate 360 degrees in the forward direction (counterclockwise) by the voltages shown in the drive waveforms O1 to O4 by the first drive pulse SP11 to fourth drive pulse SP14. As described above, the step motor drive device 20 according to the first embodiment supplies the voltages shown in the drive waveforms O1 to O4 by the drive pulse train SP10 to the step motor 40, thereby enabling the step motor 40 to be driven to rotate in the forward direction (counterclockwise).

In FIG. 5, the drive waveforms O1 to O4 by the drive pulse SP11 or drive pulse SP13 that excite both coil A and coil B are referred to as the first drive voltage, and the drive waveforms O1 to O4 by the drive pulse SP12 or drive pulse SP14 that excite only one of coil A or coil B are referred to as the second drive voltage. Then, the driver circuit 30 rotates the rotor 41 by 90 degrees or more (135 degrees in the example of FIG. 5) by the first drive voltage, and rotates the rotor 41 by 180 degrees by the first drive voltage and the second drive voltage. Furthermore, the rotor 41 is driven to rotate by applying the first drive voltage and the second drive voltage alternately and continuously to coil A and/or coil B. The angle by which the rotor 41 is rotated by the first drive voltage is not limited to 135 degrees, and can be appropriately determined according to the characteristics of the step motor 40, etc., as long as it is 115 degrees or more and 150 degrees or less.

Figure 7 (a) shows an example of drive waveforms O1' to O4' produced by the reverse drive pulse train SP10', and Figures 7 (b) to (f) are operation diagrams of the step motor 40 produced by the reverse drive pulse train SP10'. Using Figure 7, we will explain the case where the rotor 41 of the step motor 40 is driven in the reverse direction (clockwise).

FIG. 7A shows reverse drive waveforms O1' to O4' by a reverse drive pulse train SP10' for driving the rotor 41 of the step motor 40 in the reverse direction (clockwise). As will be described later, the reverse drive waveforms O1' to O4' are also divided into four states depending on the four drive states of the step motor 40, but the eight transistors of the driver circuit 30 are The first reverse rotation drive pulse SP11' defines the ON/OFF state. Similarly, the second reverse drive pulse SP12' defines the ON/OFF state of the eight transistors of the driver circuit 30 so that the driver circuit 30 is in the second state, and the driver circuit 30 is brought into the third state. The third reverse drive pulse SP13' defines the ON/OFF state of the eight transistors of the driver circuit 30, and the third reverse drive pulse SP13' defines the ON/OFF state of the eight transistors of the driver circuit 30 so as to reach the fourth state. This is the fourth reverse rotation drive pulse SP14'. Furthermore, the first to fourth reverse drive pulses SP11' to SP14' are collectively referred to as a reverse drive pulse train SP10'.

As shown in FIG. 7(b), the starting position of the north pole of the rotor 41 is at 225 degrees counterclockwise from the 0 degree position shown in FIG. 3. Note that the amount of movement caused by driving with each pulse is shown as an example, and can usually be adjusted as desired by the design of the stator 42.

FIG. 7(c) shows a state in which the voltages shown in the reverse motion waveforms O1' to O4' due to the first reverse drive pulse SP11' are supplied to the coil terminals O1 to O4 of the step motor 40, and the coil A drive current flows through both coils A and B, and both coils A and B are excited in the direction of the arrow (the opposite direction to FIG. 6(b)). As a result, the first magnetic pole part 45a is magnetized to the south pole, the second magnetic pole part 45b is magnetized to the north pole, and the third magnetic pole part 45c is not magnetized because the magnetization cancels each other out. As a result, the S pole of the rotor 41 and the N pole of the second magnetic pole part 45b attract each other, the N pole of the rotor 41 and the S pole of the first magnetic pole part 45a attract each other, and the N pole of the rotor 41 rotates clockwise. Rotate approximately 135 degrees from the starting position of 225 degrees to the 90 degree position.

Next, FIG. 7(d) shows the state in which the voltages shown in the reverse drive waveforms O1'-O4' by the second reverse drive pulse SP12' are supplied to the coil terminals O1-O4 of the step motor 40, and a drive current flows only through coil A, exciting it in the direction of the arrow. As a result, the first magnetic pole portion 45a is magnetized to an S pole, the third magnetic pole portion 45c is magnetized to an N pole, and since coil B is not excited, the second magnetic pole portion 45b becomes the same N pole as the third magnetic pole portion 45c. As a result, the S pole of the rotor 41 is attracted to the second magnetic pole portion 45b and the third magnetic pole portion 45c, and the N pole of the rotor 41 continues to rotate clockwise without stopping, rotating approximately 45 degrees from the 90 degree position to the 45 degree position.

At this point, the rotor 41 has been rotated 180 degrees in the reverse direction (clockwise) based on the start position of the reverse steady rotation by the first reverse drive pulse SP11' and the second reverse drive pulse SP12'.

Next, FIG. 7(e) shows a state in which the voltages shown in the reverse motion waveforms O1' to O4' due to the third reverse drive pulse SP13' are supplied to the coil terminals O1 to O4 of the step motor 40. As a result, a drive current flows through both coil A and coil B, and both coils A and B are excited in the direction of the arrow (the opposite direction to FIG. 7(c)). As a result, the first magnetic pole part 45a is magnetized to the north pole, the second magnetic pole part 45b is magnetized to the south pole, and the third magnetic pole part 45c is not magnetized because the magnetization cancels each other out. As a result, the S pole of the rotor 41 and the N pole of the first magnetic pole part 45a attract each other, the N pole of the rotor 41 and the S pole of the second magnetic pole part 45b attract each other, and the N pole of the rotor 41 rotates clockwise. Rotate about 135 degrees from the 45 degree position to the 270 degree position.

Next, FIG. 7(f) shows the state in which the voltages shown in the reverse drive waveforms O1'-O4' by the fourth reverse drive pulse SP14' are supplied to the coil terminals O1-O4 of the step motor 40, and a drive current flows only through coil A, exciting coil A in the direction of the arrow (opposite direction from FIG. 7(d)). As a result, the first magnetic pole portion 45a is excited to the N pole, the third magnetic pole portion 45c is magnetized to the S pole, and coil B is not excited, so the second magnetic pole portion 45b becomes the same S pole as the third magnetic pole portion 45c. As a result, the N pole of the rotor 41 and the S poles of the second magnetic pole portion 45b and the third magnetic pole portion 45c attract each other, and the N pole of the rotor 41 continues to rotate clockwise without stopping, rotating about 45 degrees from the 270 degree position to the 225 degree position, which is the start position of the reverse steady rotation.

At this point, the rotor 41 is rotated 360 degrees in the reverse direction (clockwise) by the voltages shown in the reverse drive waveforms O1' to O4' by the first reverse drive pulse SP11' to fourth reverse drive pulse SP14'. As described above, the step motor drive device 20 according to the first embodiment is capable of rotating the step motor 40 in the reverse direction (clockwise) by supplying the voltages shown in the reverse drive waveforms O1' to O4' by the reverse drive pulse train SP10' to the step motor 40. The reverse drive described with reference to FIG. 7 can also be performed in the step motor drive devices according to the second and third embodiments described below.

[Comparative Example]
8 is a diagram showing drive waveforms O1 to O4 shown as comparative examples, and an operation diagram of the step motor 40 by the drive waveforms O1 to O4 shown as comparative examples. Using FIG. 8, a comparative example in which the rotor 41 of the step motor 40 described above is driven in the forward direction (counterclockwise) will be described.

FIG. 8(a) shows outputs to coil terminals O1 to O4 in order to rotate the rotor 41 in the normal rotation direction (counterclockwise) from a state where the N pole is at the starting position of steady rotation of 135 degrees. 4 shows four drive waveforms O1 to O4 in a comparative example.

In the comparative example, the drive waveforms O1 to O4 are also divided into three states according to the three drive states of the step motor 40, and the first drive pulse SP21 defines the first state. Similarly, the second drive pulse SP22 defines the second state, and the third drive pulse SP23 defines the third state. Furthermore, the first to third drive pulses SP21 to SP23 are collectively referred to as a drive pulse train SP20.

As shown in FIG. 8(b), the starting position of the north pole of the rotor 41 is assumed to be 135 degrees counterclockwise from the 0 degree position shown in FIG.

Next, FIG. 8(c) shows a state in which voltages shown in dynamic waveforms O1 to O4 due to the first drive pulse SP21 are supplied to the coil terminals O1 to O4 of the step motor 40, and the coil A, A drive current flows through both coils B, and both coils A and B are excited in the directions of the arrows. As a result, the first magnetic pole part 45a is magnetized to the north pole, the second magnetic pole part 45b is magnetized to the south pole, and the third magnetic pole part 45c is not magnetized because the magnetization cancels each other out. As a result, the N pole of the rotor 41 and the S pole of the second magnetic pole part 45b attract each other, the S pole of the rotor 41 and the N pole of the first magnetic pole part 45a attract each other, and the N pole of the rotor 41 rotates counterclockwise. , rotates approximately 135 degrees from the steady rotation starting position of 135 degrees to a position of 270 degrees.

Next, FIG. 8(d) shows a state in which the voltages shown in the waveforms O1 to O4 by the second drive pulse SP22 are supplied to the coil terminals O1 to O4 of the step motor 40, and a drive current flows through both coils A and B, exciting both coils A and B in the direction of the arrows. This causes the first magnetic pole portion 45a and the second magnetic pole portion 45b to be magnetized as S poles, and the third magnetic pole portion 45c to be magnetized as N poles. As a result, the S pole of the rotor 41 and the N pole of the third magnetic pole portion 45c attract each other, and the N pole of the rotor 41 attracts the S poles of both the first magnetic pole portion 45a and the second magnetic pole portion 45b, so that the N pole of the rotor 41 further rotates counterclockwise, rotating approximately 90 degrees from the 270 degree position to the 0 degree position.

Next, FIG. 8(e) shows a state in which the voltages shown in the drive waveforms O1 to O4 by the third drive pulse SP23 are supplied to the coil terminals O1 to O4 of the step motor 40, and drive current flows only through coil B, exciting coil A in the direction of the arrow. As a result, the second magnetic pole portion 45b is excited to the N pole, the third magnetic pole portion 45c is magnetized to the S pole, and since coil A is not excited, the first magnetic pole portion 45a becomes the same S pole as the third magnetic pole portion 45c. As a result, the N pole of the rotor 41 attracts the N poles of the first magnetic pole portion 45a and the third magnetic pole portion 45c, and the N pole of the rotor 41 continues to rotate counterclockwise without stopping, rotating approximately 135 degrees from the 0 degree position to the 135 degree position, which is the start position of steady rotation.

At this point, the rotor 41 has been rotated 360 degrees from the steady rotation starting position of 135 degrees by the voltages shown in drive waveforms O1 to O4 by the drive pulse train SP20. As described above, according to the rotational drive of the comparative example, rotational drive is made possible by supplying the drive pulse train SP20 to the step motor 40.

Figure 9 is a diagram for explaining the comparison between the drive waveform produced by the drive pulse train SP10 shown in Figure 5 and the drive waveform produced by the drive pulse train SP20 shown as a comparative example in Figure 8.

The drive waveforms O1 to O4 by the drive pulse train SP20 shown in the lower part of FIG. 9 are shown in FIG. 8 as a comparative example, and are shown to switch at ideal time intervals that allow the rotor 41 to drive stably without stepping out. On the other hand, the drive waveforms O1 to O4 by the drive pulse train SP10 shown in the upper part of FIG. 9 are shown in FIG. 5 as being output to the step motor 40 by the step motor drive device 20 according to the first embodiment. Also, the drive waveforms O1 to O4 by the drive pulse train SP10 are shown to switch at ideal time intervals that allow the rotor 41 to drive stably without stepping out, based on the application time interval of the drive waveforms O1 to O4 by the drive pulse train SP20. The upper part of FIG. 9 shows positions 91 to 95 of the rotor 41 corresponding to the drive pulse train SP10, and the lower part of FIG. 8 shows positions 96 to 99 of the rotor 41 corresponding to the drive pulse train 20.

At time T0, no pulses have been applied yet, so the rotor 41 is at positions 91 and 96, which are 135 degrees from the starting point, which is the starting position of steady rotation, in both cases of drive pulse train SP10 and drive pulse train SP20. .

Next, in the T1 interval, the drive pulse SP11 and the drive pulse SP21 apply voltages based on the same drive waveform to the step motor 40 to rotate the rotor 41 by 135 degrees. Therefore, the pulse application times of the drive pulse trains SP11 and SP21 are the same, and the rotor 41 is at positions 92 and 97.

Next, in the T2 section, drive pulse SP12 energizes only coil B to drive rotor 41 to rotate 45 degrees, and drive pulse SP22 energizes coils A and B simultaneously to drive rotor 41 to rotate 90 degrees for the same pulse application time. Since the driving force when two coils are used is twice as much as the driving force when one coil is used, the target movement angle differs between drive pulse SP12 and drive pulse SP22, but both drive pulse SP12 and drive pulse SP22 can complete driving in the same application time T2.

Next, in the T3 section, the drive pulse SP13 simultaneously energizes coils A and B to rotate the rotor 41 by 135 degrees, resulting in the same pulse application time as SP11 in the T1 section, and the rotor 41 being at position 94. Furthermore, in the T4 section, the drive pulse SP14 energizes only coil B to rotate it by 45 degrees, resulting in the same application time as SP12 in the T2 section. At the end of the T4 section, the drive pulse train SP10 causes the rotor 41 to rotate 360 degrees from the starting point, resulting in position 95.

On the other hand, in the T3 interval, T4 interval, and T5 interval, the drive pulse SP23 is energized only to the coil B, and drives the rotor 41 to rotate by 135 degrees. Note that since the drive pulse SP23 is intended to obtain a large rotation angle using one coil, the pulse application time is long. At the end of the T5 period, the drive pulse train SP20 causes the rotor 41 to rotate 360 degrees from the starting point to a position 99.

In this way, when comparing the drive pulse train SP10 and the drive pulse train SP20, when the drive pulse train SP10 is used, the time for the rotor 41 to rotate 360 degrees is shorter by the T5 section (about 9%). With the drive pulse train SP10, the total rotation angle for exciting and driving both coil A and coil B during one rotation is 270 degrees, and the total rotation angle for exciting and driving only coil B is 90 degrees. On the other hand, with the drive pulse train SP20 shown as a comparative example, the total rotation angle for exciting and driving both coil A and coil B during one rotation is 225 degrees, and the total rotation angle for exciting and driving only coil B is 135 degrees. Therefore, the drive pulse train SP10 excites and drives two coils by 45 degrees more. The driving force obtained by exciting both coils A and B is twice the driving force obtained by exciting either coil A or coil B alone, so the driving pulse train SP10 can send the next pulse earlier by section T5 in Figure 8 compared to the conventional driving pulse train SP20, allowing for high-speed driving that is approximately 9% faster than conventional driving pulse trains.

Furthermore, in the conventional drive pulse train SP20, if the drive pulse SP23 is aborted in the T4 interval and the next drive pulse SP21 is output without outputting the drive pulse SP23 in the T5 interval, the rotational operation of the rotor 41 is caused by the switching of the pulses. The risk of losing synchronization is extremely high. On the other hand, in the drive pulse train SP10, step-out does not occur even if the T5 section is not provided, so high-speed driving is possible while ensuring stability.

FIG. 10 is a diagram showing the time difference between the drive pulse train SP10 and the drive pulse train SP20 when the angle at which the rotor 41 is rotated by the first drive voltage is changed. 10(a) shows a case where the angle of rotation of the rotor 41 is 115 degrees, FIG. 10(b) shows a case where the angle of rotation of the rotor 41 is 135 degrees, and FIG. 10(c) shows a case where the angle of rotation of the rotor 41 is 135 degrees. The case where the angle of rotation is 150 degrees is shown.

In FIGS. 10(a) to (c), the horizontal axis indicates the application time of the drive pulse using the length of the T1 section of the drive pulse train SP10 and the drive pulse train SP20 as a reference unit, and the vertical axis indicates the rotation angle. In FIGS. 10A to 10C, waveform W11 indicates the angle when the rotor 41 is rotated by the drive pulse train SP10, and waveform W12 indicates the angle when the rotor 41 is rotated by the drive pulse train SP20.

When the angle at which the rotor 41 is rotated by the first drive voltage is 115 degrees, the time required to rotate the step motor 40 360 degrees by the drive pulse train SP10 is about 1% faster than the time required to rotate the step motor 40 360 degrees by the drive pulse train SP10. When the angle at which the rotor 41 is rotated by the first drive voltage is 113 degrees or more, the time required to rotate the step motor 40 360 degrees by the drive pulse train SP10 is faster than the time required to rotate the step motor 40 360 degrees by the drive pulse train SP10. In the present invention, the minimum angle at which the rotor 41 is rotated by the first drive voltage is set to 115 degrees, which is 113 degrees plus a margin.

When the angle at which the rotor 41 is rotated by the first drive voltage is 135 degrees, the time it takes to rotate the step motor 40 360 degrees by the drive pulse train SP10 is 9 degrees longer than the time it takes to rotate the step motor 40 360 degrees by the drive pulse train SP10. % faster.

When the angle at which the rotor 41 is rotated by the first drive voltage is 150 degrees, the time it takes to rotate the step motor 40 360 degrees by the drive pulse train SP10 is 15 degrees longer than the time it takes to rotate the step motor 40 360 degrees by the drive pulse train SP10. % faster. When the rotor 41 is rotated by the first drive voltage, current is passed through the two coils, so as the angle at which the rotor 41 is rotated by the first drive voltage is increased, the current is consumed when driving the step motor 40. power consumption increases. In the present invention, from the viewpoint of suppressing power consumption when driving the step motor 40, the maximum value of the angle at which the rotor 41 is rotated by the first drive voltage is 150 degrees.

Second Embodiment
11 is a schematic diagram of a step motor drive device 50 according to a second embodiment of the present invention. The step motor drive device 50 can be applied to the electronic timepiece 10 described above, and is an example that achieves improved drive stability, reduced power consumption, and even higher drive speeds by providing a mechanism for detecting the rotation of the rotor 41.

As shown in FIG. 11, the step motor drive device 50 includes an oscillation circuit 21, a control circuit 52, a drive pulse generation circuit 53, a detection pulse generation circuit 54, a correction pulse generation circuit 55, a pulse selection circuit 56, and a driver circuit. Including 60. The step motor drive device 50 is implemented, for example, as an integrated circuit including a microcontroller. The oscillation circuit 21 and the step motor 40 are the same as those shown in FIG. 2, so their explanation will be omitted.

The control circuit 52 generates control signals CN2, CN3, and CN4, and inputs them to the drive pulse generation circuit 53, detection pulse generation circuit 54, and correction pulse generation circuit 55, respectively. The drive pulse generation circuit 53 generates a drive pulse train SP30 for driving the step motor 40 based on the control signal CN2, and outputs it to the pulse selection circuit 56. The detection pulse generation circuit 54 generates a detection pulse CP for detecting that the rotor 41 of the step motor 40 rotates normally, based on the control signal CN3, and outputs it to the pulse selection circuit 56. The correction pulse generation circuit 55 generates a correction pulse FP for assisting the driving of the step motor 40 based on the control signal CN4, and outputs it to the pulse selection circuit 56. Note that the control circuit 52 includes a memory and stores variables corresponding to the pulse application direction, which will be described later.

The pulse selection circuit 56 selects the input drive pulse train SP30, detection pulse CP, and correction pulse FP, and outputs them to the driver circuit 60 at appropriate timing. The driver circuit 60 generates drive waveforms O1 to O4 based on the pulses selectively input from the pulse selection circuit 56, and supplies them to the step motor 40.

The rotation detection determination circuit 57 detects the induced current in the rotor 41 of the step motor 40 based on the detection signal CS detected by supplying the detection pulse CP to the coils A and B of the step motor 40, and determines whether or not there is rotation. is determined, and the determination result CK is output. The output determination result CK is input to the pulse selection circuit 56 and used for pulse switching control.

Figure 12 is a circuit diagram showing an example of a driver circuit 60.

The driver circuit 60 shown in FIG. 12 has a configuration for outputting drive waveforms O1 to O4 supplied to the coil A and the coil B (transistors P1 to 4 which are P channel MOS transistors and transistor N1 which is an N channel MOS transistor). 4) are the same as the driver circuit 30 shown in FIG. 4.

Driver circuit 60 differs from driver circuit 30 in that it further includes transistors TP1 and TP2 that are P-channel MOS transistors, and transistors TP3 and TP4 that are P-channel MOS transistors. Transistors TP1 and TP2 are connected to coil terminals O1 and O2 of coil A, respectively, via a detection resistor, and transistors TP3 and TP4 are connected to coil terminals O3, O4 of coil B, respectively, via a detection resistor. There is.

Although the detection of the rotation of the step motor itself is a well-known technique, in order to make the following explanation easier to understand, the detection of the rotation of the step motor 40 by the detection pulse CP and the rotation detection determination circuit 57 will be described below.

As shown in FIG. 3, the stator 42 of the step motor 40 is provided with a narrowed portion 46 and a slit 47. While the rotor 41 is rotating, and while the rotor 41 is rotating freely due to inertia, the magnetism generated in the stator by electromagnetic induction has difficulty passing through the narrowed portion 46 and the slit 47, which have a large magnetic resistance, and most of the magnetism takes a path that passes through coil A or coil B. Therefore, the induced current induced by the rotation of the rotor 41 can be detected using coils A and B.

In the driver circuit 60 shown in FIG. 12, a detection pulse CP is applied to the gates of transistors TP1 to TP4 at a predetermined timing to turn on each transistor, and the magnitude of the induced current generated in the coil terminals O1 to O4 can be extracted as a detection signal CS, which is a voltage signal. Based on the detection signal CS, the detection judgment circuit 57 judges whether the rotor 41 is rotating or not, and outputs the judgment result CK.

Note that when detecting the induced current flowing in the coil A or the coil B, a driving current cannot be caused to flow in the coil. In other words, rotation cannot be detected when a drive pulse in which drive current flows through both coil A and coil B is output. Therefore, when a drive current is flowing through either the coil A or the coil B, the coil on the side where the drive current is not flowing is used for rotation detection.

FIG. 13 is a diagram for explaining rotation and non-rotation of the rotor 41 of the step motor 40.

Figure 13(a) shows a case where the rotor 41 is not rotating, that is, even though a drive waveform is applied to the coil, the rotor 41 does not rotate to the desired angle and fails to rotate. That is, when a drive waveform is applied to the coil, the rotor 41 rotates counterclockwise once, but because the driving force is insufficient, the rotor 41 rotates counterclockwise due to the holding torque and is returned to 0 degrees, which is the static stable point. In this case, the rotor 41 does not rotate at all in the end, so this is called non-rotation. In Figure 13(a), the rotation of the rotor 41 during the period when the drive waveform is applied to the coil is shown by a dashed line.

FIG. 13(b) shows a case where the rotor 41 rotates, that is, the drive waveform is applied to the coil, the rotor 41 rotates to a desired angle, and the rotation is successful. That is, by applying the drive waveform to the coil, the rotor 41 rotates counterclockwise by a certain angle or more, and even after the application of the drive waveform stops, it continues to rotate counterclockwise due to the holding torque and reaches the rotation target position. It is rotated up to 180 degrees. In this case, the rotor 41 has finally rotated to the target rotational position, so this is referred to as rotation.

In this way, the behavior of the rotor 41 after the drive pulse is output differs depending on whether the rotor 41 is rotating or not, and therefore the waveforms of the induced currents generated in coils A and B are also different. The rotation detection and determination circuit 57 extracts this difference in waveforms as a detection signal CS and determines whether the rotor is rotating or not.

FIG. 14(a) shows an example of drive waveforms O1 to O4, and FIG. 14(b) is a table showing the operation of each transistor according to the drive pulse train SP30 and the detection pulse CP.

Figure 14(a) shows the drive waveforms O1 to O4 output from the driver circuit 60 to the coil terminals O1 to O4, and the drive pulse train SP30 for generating the drive waveforms O1 to O4. The drive waveforms O1 to O4 and the drive pulse train SP30 in Figure 14(a) are the same as the drive waveforms O1 to O4 and the drive pulse train 10 in Figure 5(a).

In the following, the drive pulse train SP30 is divided into four parts: a first fixed drive pulse SP31, a second variable drive pulse SP32, an inverted first fixed drive pulse SP33, and an inverted second variable drive pulse SP34. As described below, the lengths (periods) of the second variable drive pulse SP32 and the inverted second variable drive pulse SP34 change depending on the conditions. In contrast, the lengths of the first fixed drive pulse SP31 and the inverted first fixed drive pulse SP33 are fixed and predetermined.

FIG. 14(b) is a table showing the ON/OFF states of eight transistors of the driver circuit 60 for generating drive waveforms O1 to O4 and the ON/OFF states of transistors TP1 to TP4. Note that the ON/OFF states of the eight transistors P1 to P4 and N1 to N4 of the driver circuit 60 for generating the drive waveforms O1 to O4 are the same as those in FIG. 5(b), so the explanation thereof will be omitted. .

Rotation detection will be described below using a table showing the ON/OFF states of the transistors TP1 to TP4 in FIG. 14(b).

No rotation detection is performed during the period in which the first fixed drive pulse SP31 is output. Therefore, all transistors TP1 to TP4 are turned off by the detection pulse CP.

Next, during the period in which the second variable drive pulse SP32 is output, only the coil B is excited, so the coil A is used for rotation detection. Therefore, only the transistor TP1 is turned on by the detection pulse CP, and all the transistors TP2 to TP4 are turned off.

Next, rotation detection is not performed during the period when the inverted first fixed drive pulse SP33 is output. Therefore, the detection pulse CP turns off all of the transistors TP1 to TP4.

Finally, during the period in which the inverted second variable drive pulse SP34 is output, only the coil B is excited, so the coil A is used for rotation detection. Therefore, only the transistor TP1 is turned on by the detection pulse CP, and all the transistors TP2 to TP4 are turned off.

Figure 15 shows an example of a pulse waveform output from the drive pulse generating circuit 53.

The pulse waveforms shown in Figures 15(a) to 15(c) show examples of the drive pulse train output to the driver circuit 60 when the rotor 41 is determined to be rotating, that is, the first fixed drive pulse SP31 and the second variable drive pulse SP32, or the inverted first fixed drive pulse SP33 and the inverted second variable drive pulse SP34. (Hereinafter, the "first fixed drive pulse SP31 or the inverted first fixed drive pulse SP33" will be abbreviated as the "first fixed drive pulse SP31/SP33", and the "second variable drive pulse SP32 or the inverted second variable drive pulse SP34" will be abbreviated as the "second variable drive pulse SP32/SP34".) In addition to those shown in Figures 15(a) to 15(c), the type of drive pulse waveform to be selected will vary depending on the result of rotation detection. Figure 15(d) shows the correction pulse FP output to the driver circuit 60 when the rotor 41 is determined to be non-rotating. Also, FIG. 15(e) shows the timing at which a detection pulse CP for rotation detection is output to the driver circuit 60.

In this embodiment, the first fixed drive pulses SP31/SP33 are output for 5 ms. The second variable drive pulses SP32/SP34 are output after the first fixed drive pulses SP31/SP33 are output, and the length can be selected from five lengths in 1 ms increments, from 1 ms to 5 ms. The length of the variable drive pulses SP32/SP34 is determined based on the results of rotation detection. This will be explained in more detail later, but the basic idea is to continue outputting the variable drive pulses SP32/SP34 until rotation is determined.

If rotation is not determined even after outputting the variable drive pulses SP32/SP34 with the longest length (5 ms), the correction pulse FP shown in FIG. 15(d) is output to assist the rotation of the rotor 41. Note that the correction pulse FP is output to prevent the rotor 41 from losing synchronism when it is determined that the rotor 41 is not rotating, and its waveform is set to have a stronger driving force. In this case, it is a 5 ms pulse.

The detection pulse CP is a 16 μs wide pulse that is output every 0.5 ms from 0.25 ms until 4.75 ms after the start of output of the variable drive pulses SP32/SP34.

The lengths and shapes of the first fixed drive pulses SP31/SP33, the second variable drive pulses SP32/SP34, the correction pulses FP, the output timing of the detection pulses CP, etc. in the above description are merely examples, and the shape of the step motor 40 is It may be changed depending on various configurations such as size, load of the object to be driven, etc.

Figure 16 is a diagram for explaining the correction pulse FP. Figure 16 (a) shows an example of the drive waveforms O1 to O4 applied to the step motor 40 when the correction pulse FP is output after the second variable drive pulse SP32 in the drive pulse train SP30.

In FIG. 16(a), the drive waveforms O1 to O4 generated by the drive pulse train SP30 output before and after the correction pulse FP are the same as those described in FIG. 14, so their description will be omitted. The drive waveforms O1 and O4 generated by the correction pulse FP have a voltage of -V (v), and the drive waveforms O3 and O2 have a voltage of 0 (v). As a result, a drive current flows through both coils A and B of the step motor 40, exciting both coils A and B.

Figure 16 (b) is a table showing the ON/OFF states of the eight transistors P1 to P4 and N1 to N4 of the driver circuit 60 due to the correction pulse FP. In the driver circuit 60, transistors N1 and P2 are ON, transistors P1 and N2 are OFF, drive current flows from coil terminal O2 to coil terminal O1, and coil A is excited. Similarly, transistors P3 and N4 are ON, transistors N3 and P4 are OFF, drive current flows from coil terminal O4 to coil terminal O3, and coil B is excited.

Figures 17(a) to (f) are diagrams for explaining the operation of the step motor 40 by the correction pulse FP shown in Figure 16.

Figure 17 (a) shows the initial state of the step motor 40, with the starting position of the north pole of the rotor 41 being 135 degrees counterclockwise from the 0 degree position shown in Figure 3. Note that the amount of movement caused by driving with each pulse is shown as an example, and can usually be adjusted as desired by the design of the stator 22.

Figure 17 (b) shows the state in which the voltages shown in the drive waveforms O1 to O4 by the first fixed drive pulse SP31 are supplied to the step motor 40. In this case, the first magnetic pole portion 22a is magnetized to the N pole, the second magnetic pole portion 22b is magnetized to the S pole, and the third magnetic pole portion 22c is not magnetized because the magnetizations cancel each other out. As a result, the N pole of the rotor 41 and the S pole of the second magnetic pole portion 22b attract each other, and the S pole of the rotor 41 and the N pole of the first magnetic pole portion 22a attract each other, causing the rotor 41 to rotate counterclockwise, rotating approximately 135 degrees from the starting position of steady rotation (a position 135 degrees counterclockwise from the 0 degree position shown in Figure 3) to a position of 270 degrees.

Next, FIG. 17(c) shows a state in which voltages shown in drive waveforms O1 to O4 by the second variable drive pulse SP32 are supplied to the step motor 40. In this case, the second magnetic pole part 22b is magnetized to the S pole, the third magnetic pole part 22c is magnetized to the N pole, and since the coil A is not excited, the first magnetic pole part 22a becomes the same N pole as the third magnetic pole part 22c. Normally, the S pole of the rotor 41 and the N poles of the first magnetic pole part 22a and the third magnetic pole part 22c attract each other, and the N pole of the rotor 41 moves further counterclockwise from a position of 270 degrees to 315 degrees without stopping. Attempts are made to rotate it approximately 45 degrees to the position of 45 degrees. However, if it is not possible to reach the 315 degree position due to the magnitude of the load of the object to be driven, the power supply voltage, disturbances, etc., the rotor 41 moves to the desired position as shown in FIG. 17(c). does not rotate, and the rotation detection and determination circuit 57 determines that it is not rotating.

Next, FIG. 17(d) shows a state in which voltages shown in drive waveforms O1 to O4 by the auxiliary pulse FP are supplied to the step motor 40 in response to a determination that the rotor 41 is not rotating. In this case, a drive current (not shown) flows through the coil A from the coil terminal O2 to O1, and the coil A is excited in the direction of the arrow. Similarly, in coil B, a drive current (not shown) flows from coil O3 to coil O4, and is excited in the direction of the arrow. As a result, the first magnetic pole part 22a and the second magnetic pole part 22b are magnetized to the south pole, and the third magnetic pole part 22c is magnetized to the north pole. As a result, the S pole of the rotor 41 and the N pole of the third magnetic pole portion 22c attract each other, forcing the N pole of the rotor 41 to rotate to the 0 degree position.

Next, FIG. 17(e) shows the state in which the voltages shown in the drive waveforms O1 to O4 by the inverted first fixed drive pulse SP33 are supplied to the step motor 40. In this case, the first magnetic pole portion 22a is magnetized to the S pole, the second magnetic pole portion 22b is magnetized to the N pole, and the third magnetic pole portion 22c is not magnetized because the magnetizations cancel each other out. As a result, the N pole of the rotor 41 and the S pole of the first magnetic pole portion 22a attract each other, and the S pole of the rotor 41 and the N pole of the second magnetic pole portion 22b attract each other, and the N pole of the rotor 41 rotates counterclockwise, rotating approximately 90 degrees from the 0 degree position to the 90 degree position.

Next, FIG. 17(f) shows a state in which voltages shown in drive waveforms O1 to O4 by the inverted second variable drive pulse SP34 are supplied to the step motor 40. In this case, the second magnetic pole part 22b is magnetized to the north pole, the third magnetic pole part 22c is magnetized to the south pole, and since the coil A is not excited, the first magnetic pole part 22a becomes the same south pole as the third magnetic pole part 22c. As a result, the N pole of the rotor 41 attracts the S poles of the first magnetic pole section 22a and the third magnetic pole section 22c, and the N pole of the rotor 41 further rotates counterclockwise without stopping, and rotates 90 degrees. It rotates about 45 degrees from the position to the 135 degree position, which is the starting position of steady rotation.

As described above, when the rotation detection result is determined to be non-rotation, an auxiliary pulse FP that assists rotation is output, assisting the rotation of the rotor 41 of the step motor 40 and preventing loss of synchronization. Although not shown, when an auxiliary pulse FP is output after the output of the inverted second drive pulse SP34, the drive waveform corresponding to the auxiliary pulse FP shown in FIG. 16(a) is output to the step motor 40 after swapping drive waveforms O1 and O2 and swapping drive waveforms O3 and O4.

FIG. 18 is an operation flow diagram of the step motor drive device 50 according to the second embodiment. Hereinafter, the operation of the step motor drive device 50 shown in FIG. 11 will be explained according to this flowchart.

First, the step motor drive device 50 selects the first fixed drive pulse SP31/SP33 generated by the drive pulse generation circuit 53 using the pulse selection circuit 56 and outputs it to the driver circuit 60 (ST1). Which of the first fixed drive pulse SP31 and the inverted second fixed pulse SP33 is output is determined based on a variable indicating the pulse application direction stored in a steering storage means (not shown) included in the control circuit 52. .

Next, the step motor drive device 50 selects the second variable drive pulse SP32/SP34 generated by the drive pulse generation circuit 53 using the pulse selection circuit 56 and outputs it to the driver circuit 60 (ST2). Which of the first variable drive pulse SP32 and the inverted second variable drive pulse SP34 is output is determined based on a variable indicating the pulse application direction stored in a steering storage means (not shown) included in the control circuit 52. Ru.

Next, the step motor drive device 50 transfers the detection pulse CP output from the detection pulse generation circuit 54 to the pulse selection circuit 56 every 5 ms after 0.25 ms has elapsed since the output of the second variable drive pulse SP32/SP34. is selected and output to the driver circuit 60, and rotation detection is started (ST3). Based on the detection signal CS obtained as a result, the rotation detection determination circuit 57 outputs a determination result CK.

Figure 19 is a diagram for explaining the determination of rotation/non-rotation by the rotation detection determination circuit 57. Figure 19(c) is a diagram showing an example of drive waveforms O1 to O4 applied to coil terminals O1 to O4, Figure 19(a) is a diagram showing the waveform of the induced current generated in coil A, and Figure 19(b) is a diagram showing the waveform of the induced current generated in coil B.

From time 0 ms, current flows between the coil terminals O3 and O4 of the coil B, and the coil B is excited by the drive waveforms O1 to O4 corresponding to the inverted second variable drive pulse SP34. As a result, the rotor 41 starts rotating, and positive induced currents are generated in the coils A and B. A voltage corresponding to the detection pulse CP is applied to the coil A, which is a different coil from the coil to which the inverted second variable drive pulse SP34 is applied. Specifically, it is applied to the coil terminal O1 every 0.5 ms from 0.25 ms after the start, thereby obtaining a detection signal CS corresponding to each detection pulse CP.

As is clear from the waveform of the induced current generated in the coil A shown in FIG. 19(a), at the beginning of rotation of the rotor 41, the induced current generated in the coil A has a positive sign and is not very large. Although it depends on the conditions, in the example shown here, the sign of the induced current reverses (becomes a negative sign) approximately 2.5ms after the start of rotation, and a peak in the waveform that exceeds a certain value occurs. . Note that when the rotor 41 is not rotating, the induced current does not have a negative sign. This waveform peak having a negative value indicates that the rotor 41 has overcome the potential peak and is rotating toward the target static stable point. Rotation can be detected by detecting the peaks of the waveform with negative signs shown by hatching in FIG. 19(a).

The detection signal CS detected from the coil terminal O1 is compared with a predetermined negative threshold th. As shown in FIG. 19(c), in this example, the detection pulse CP2.75 after 2.75 ms from the start of rotation does not fall below the threshold th, and the detection pulse CP3 after 3.25 ms from the start of rotation At .25, it falls below the threshold th for the first time.

The rotation detection determination circuit 57 determines that the rotation is occurring when the detection signal CS that is lower than the threshold th is obtained twice in succession. Therefore, when the detection signal CS based on the detection pulse CP3.75 is detected after 3.75 ms has elapsed from the start of rotation, the rotation detection determination circuit 57 determines rotation and outputs the determination result CK. Furthermore, if two consecutive detection signals CS are not obtained even after 4.75 ms have elapsed from the start of rotation, it is determined that the rotation is non-rotating, and a determination result CK is output.

The timing at which a detection signal CS that falls below the threshold value th twice in a row is obtained varies depending on various conditions, such as the size of the load to be driven and the power supply voltage. In addition, the conditions for judgment are not limited to two consecutive signals, but may be one, three or more consecutive signals, or the number of signals obtained within a specified period may be added up to a specified number or more.

Returning to FIG. 18, after the start of rotation detection, the timing at which rotation determination is obtained is monitored. First, it is determined whether the detection signal CS has been obtained twice in succession within 0.75 ms from the start of rotation (ST41). When the detection signal CS is obtained twice (ST41: Y), the rotation detection is finished (ST51), the output of the detection pulse CP is stopped, and the width of the second variable drive pulse SP32/SP34 is set to 1 ms ( ST61). As a result, the output of the second variable drive pulses SP32/SP34 ends in 1 ms.

If the detection signal CS is not obtained twice in succession within 0.75 ms from the start of rotation (ST41: N), then it is determined whether the detection signal CS is obtained twice in succession within 1.75 ms (ST42). If it is obtained (ST42: Y), the rotation detection is terminated (ST52), the width of the second variable drive pulse SP32/SP34 is set to 2 ms (ST62), and the output of the second variable drive pulse SP32/SP34 is terminated at 2 ms.

If the detection signal CS is not obtained twice in succession within 1.75 ms from the start of rotation (ST42: N), then it is determined whether the detection signal CS is obtained twice in succession within 2.75 ms (ST43). If it is obtained (ST43: Y), the rotation detection is terminated (ST53), the width of the second variable drive pulse SP32/SP34 is set to 3 ms (ST63), and the output of the second variable drive pulse SP32/SP34 is terminated after 3 ms.

If the detection signal CS is not obtained twice in succession within 2.75 ms from the start of rotation (ST43: N), then it is determined whether the detection signal CS is obtained twice in succession within 3.75 ms (ST44). If it is obtained (ST44: Y), the rotation detection is terminated (ST54), the width of the second variable drive pulse SP32/SP34 is set to 4 ms (ST64), and the output of the second variable drive pulse SP32/SP34 is terminated at 4 ms.

If the detection signal CS is not obtained twice in a row within 3.75ms from the start of rotation (ST44: N), next check whether the detection signal CS is obtained twice in a row within 4.75ms. Determine (ST45). If obtained (ST45: Y), end the rotation detection (ST55), set the width of the second variable drive pulse SP32/SP34 to 5 ms (ST65), and output the second variable drive pulse SP32/SP34. ends in 5ms.

If the detection signal CS is not obtained twice in succession within 4.75 ms from the start of rotation (ST45: N), it is determined that there is no rotation, so rotation detection is terminated (ST56), and after the output of the second variable drive pulse SP32/SP34 is terminated after 5 ms (ST66), the correction pulse FP output by the correction pulse generation circuit 55 is selected by the pulse selection circuit 47, and a drive waveform corresponding to the correction pulse FP is output to the driver circuit 60 (ST7).

Next, after outputting the second variable pulse SP32/SP34 or the auxiliary pulse FP, if a stop signal is output from the step motor drive device 50, the operation is ended (ST8: Y). If the stop signal has not been issued, the process returns to ST1, inverts the variable that stores the pulse application direction stored in the control circuit 52, and then continues driving (ST8: N).

As described above, according to the second embodiment, it is possible to detect rotation/non-rotation of the rotor 41 every 180 degrees of driving, and output the correction pulse FP in the case of non-rotation, thereby ensuring that the rotor 41 is It can be rotated to Further, the length of the outputted drive pulse train is only the length required for rotation of the rotor 41, so power consumption is reduced and unnecessary energization time is eliminated, allowing high-speed drive.

By mechanically switching the wheel train in the electronic watch 10, the object driven by the step motor 40 is switched between the hands and the oscillating weight, and an appropriate pulse width can be selected and output according to the inertia of each. Even if the hands or oscillating weight are changed to one with a larger or smaller inertia, an appropriate pulse width can be selected according to the changed inertia. In other words, regardless of the inertia of the object driven by the step motor 40, an appropriate pulse width can always be selected and output using a common motor drive device.

[Modified example of second embodiment]
FIG. 20 is a diagram for explaining a modification of the second embodiment.

In the second embodiment, the pulse width of the first fixed drive pulses SP31/SP33 was fixed at 5 ms, but it can be changed according to the result of rotation detection performed during the output period of the second variable drive pulses SP32/SP34. You may also do this. Figure 20(a) shows the case of a pulse width of 5ms, Figure 20(b) shows the case of a pulse width of 4ms, and Figure 20(c) shows the case of a pulse width of 3ms. .

Immediately after the steady-state drive of the step motor 40 begins, the rotation speed of the rotor 41 has not increased sufficiently, and it takes time to detect the rotation, or the rotation cannot be detected at all. Therefore, the second variable drive pulse SP32/34 of 4 ms or more is output, as shown in ST64, ST65, and ST66 in the flowchart of FIG. 18. In such a case, the first fixed drive pulse SP31/33 also has a long pulse width of 5 ms, as shown in FIG. 20 (1).

The step motor 40 gradually increases the rotation speed of the rotor 41, and as a result of rotation detection, a second variable drive pulse SP32/34 of 2 ms or more is output, such as ST62 and ST63 in the flowchart of FIG. 18. In such a case, the first fixed drive pulse SP31/SP33 also has a pulse width of 4 ms, as shown in FIG. 20 (2).

Finally, when the rotation speed of the rotor 41 of the step motor 40 reaches the maximum value, a state is reached in which the second variable drive pulses SP32/SP34 of 1 ms are outputted, as shown in ST61 in the flowchart of FIG. In such a case, the first fixed drive pulse SP31/33 is also set to have a short pulse width of 3 ms as shown in (3).

As described above, by varying the pulse width of the first fixed drive pulses SP31/SP33, when the rotation speed of the rotor 41 is low immediately after the start of operation, it is possible to drive the rotor 41 more reliably, and as the rotation speed of the rotor 41 increases, it is possible to further increase the rotation speed. Note that the pulse widths of the first fixed drive pulses SP31/SP33 provided are not limited to three types, and may be at least three types or may be more than three types. In addition, the conditions for selecting the pulse widths of the first fixed drive pulses SP31/SP33 are arbitrary.

[Third embodiment]
21 is a schematic diagram of a step motor drive device 70 according to a third embodiment of the present invention. The step motor drive device 70 can be applied to the electronic timepiece 10 described above, and is an example in which drive reliability is improved by providing a mechanism capable of outputting a pulse that assists in starting the rotor 41, and a mechanism capable of outputting a pulse that assists in stopping the rotor 41.

As shown in FIG. 21, the step motor drive device 70 includes an oscillation circuit 21, a control circuit 52, a drive pulse generation circuit 53, a detection pulse generation circuit 54, a correction pulse generation circuit 55, a pulse selection circuit 56, and a rotation detection circuit 52. In addition to the determination circuit 57 and the driver circuit 60, it includes an initial pulse generation circuit 58 and a termination pulse generation circuit 59. The step motor drive device 70 is implemented, for example, as an integrated circuit including a microcontroller. The oscillation circuit 21 and the step motor 40 are the same as those shown in FIG. 2, so their explanation will be omitted.

The control circuit 52 generates control signals CN2, CN3, CN4, CN5, and CN6, and includes a drive pulse generation circuit 53, a detection pulse generation circuit 54, a correction pulse generation circuit 55, an initial pulse generation circuit 58, and a termination pulse generation circuit 59, respectively. Enter. The drive pulse generation circuit 53 generates a drive pulse train SP30 for driving the step motor 40 based on the control signal CN2, and outputs it to the pulse selection circuit 56. The detection pulse generation circuit 54 generates a detection pulse CP for detecting that the rotor 41 of the step motor 40 rotates normally based on the control signal CN3, and outputs it to the pulse selection circuit 56. The correction pulse generation circuit 55 generates a correction pulse FP for assisting the driving of the step motor 40 based on the control signal CN4, and outputs it to the pulse selection circuit 56. The initial motion pulse generation circuit 58 aligns the phase of the rotor 41 of the step motor 40 to the start position of steady rotation based on the control signal CN5, generates an initial motion pulse IP for assisting the start of movement, and outputs it to the pulse selection circuit 56. . The termination pulse generation circuit 59 generates a termination pulse EP for stopping the rotor 41 of the step motor 40 at a static stable point of 0 degree position or 180 degree position based on the control signal CN6, and generates a termination pulse EP based on the control signal CN6. 56. Note that the control circuit 52 includes a memory and stores variables corresponding to the pulse application direction, which will be described later.

The pulse selection circuit 56 selects the inputted drive pulse train SP30, detection pulse CP, correction pulse FP, initial pulse IP, and end pulse EP, and outputs them to the driver circuit 60 at appropriate timing. The driver circuit 60 generates drive waveforms O1 to O4 based on the pulses selectively input from the pulse selection circuit 56, and supplies them to the step motor 40.

The rotation detection and judgment circuit 57 detects the induced current in the rotor 41 of the step motor 40 based on the detection signal CS detected by the detection pulse CP supplied to coils A and B of the step motor 40, judges whether or not there is rotation, and outputs the judgment result CK. The output judgment result CK is input to the pulse selection circuit 56 and used for pulse switching control.

Figure 22 is a diagram for explaining the initial pulse train IP10. Figure 22 (a) shows an example of drive waveforms O1 to O4 corresponding to the initial pulse train IP10.

The initial pulse IP10 is used to move the N pole of the rotor 41 from the 0 degree position, which is a static stable point, to the 135 degree position, which is the start position of steady rotation, in order to drive the step motor 40 in a steady state. be. As shown in FIG. 22(a), the initial motion pulse train IP10 is composed of three drive pulses: a first initial motion pulse IP11, a second initial motion pulse IP12, and a third initial motion pulse IP13.

The first initial pulse IP11 has a drive waveform O1 with a voltage of -V (v) and drive waveforms O2, O3, and O4 with a voltage of 0 (v). This causes a drive current to flow through coil A of the step motor 40, which is connected to drive waveforms O1 and O2, and excites it.

The second drive pulse IP12 has drive waveforms O1 and O3 with a voltage of -V (v) and drive waveforms O2 and O4 with a voltage of 0 (v). This causes a drive current to flow through both coils A and B of the step motor 40, exciting both coils A and B.

In the third initial pulse IP13, the voltage of the drive waveform O3 is -V (v), and the voltage of the drive waveform O1. The voltage of O2 and O4 is 0 (v). As a result, a drive current flows through the coil B of the step motor 40, which is connected to the drive waveforms O3 and O4, and is excited.

The total pulse width of the initial pulse train IP10 can be any width. Also, while the drive waveforms O1 to O4 are illustrated as continuous full pulses, they may be chopper-type drive pulses consisting of multiple small pulse groups.

FIG. 22(b) shows the ON/OFF states of the eight transistors P1 to P4 and N1 to N4 of the driver circuit 60 according to the initial pulse train IP, and the ON/OFF states of the four transistors TP1 to TP4 of the driver circuit 60 according to the detection pulse CP. It is a table showing ON/OFF states.

The voltage of the drive waveform O1 due to the first initial pulse IP11 becomes -V (v) and the voltage of the drive waveform O2 becomes 0 (v), so transistors N1 and P2 are ON and transistors P1 and N2 are OFF, drive current flows from coil terminal O2 of coil A to coil terminal O1, and coil A is excited. The voltages of the drive waveforms O3 and O4 are both 0 (v), so transistors P3 and P4 are ON and transistors N3 and N4 are OFF, no drive current flows through coil B, and coil B is not excited.

Next, since the voltage of the drive waveform O2 by the second initial pulse IP12 becomes 0 (v) and the voltage of the drive waveform O1 becomes -V (v), the transistor N1 and the transistor P2 are turned on, and the transistor P1 and the transistor N2 are turned on. OFF, the drive current flows from the coil terminal O2 to the coil terminal O1, and the coil A is excited. Since the voltage of drive waveform O4 is 0 (v) and the voltage of drive waveform O3 is -V (v), transistor N3 and transistor P4 are turned on, transistor P3 and transistor N4 are turned off, and the drive current is transferred from coil terminal O4. The current flows to the coil terminal O3, and the coil B is excited.

Next, the voltage of the drive waveform O3 due to the initial pulse IP13 becomes -V (v) and the voltage of the drive waveform O4 becomes 0 (v), so the transistor N3 and the transistor P4 are turned on, the transistor P3 and the transistor N4 are turned off, and the drive current flows from coil terminal O4 of coil B to coil terminal O3, and coil B is excited. Since the voltages of drive waveforms O1 and O2 are both 0 (v), transistors P1 and P2 are turned on, transistors N1 and N2 are turned off, and no drive current flows through coil A, so that coil A is not excited.

In this way, each transistor of the driver circuit 60 is controlled ON/OFF by the three drive pulses IP11 to IP13 of the initial pulse train IP10, and the coils A and B of the step motor 40 are excited. Note that when the initial pulse train IP10 is output, rotation detection is not performed, so TP1 to TP4 are all OFF.

Figures 23(a) to (d) are diagrams for explaining the operation of the step motor 40 by the initial pulse train IP10 shown in Figure 22.

Figure 23 (a) shows the initial state of the step motor 40, with the north pole of the rotor 41 at 0 degrees, the static stable point. Note that the amount of movement caused by driving with each pulse is shown as an example, and can usually be adjusted as desired by the design of the stator 42.

Next, FIG. 23(b) shows a state in which drive waveforms O1 to O4 corresponding to the first initial pulse IP11 are supplied to the step motor 40, and a drive current (not shown) flows from coil end O2 to O1, exciting coil A in the direction of the arrow. As a result, the first magnetic pole portion 22a is magnetized as an S pole, and the third magnetic pole portion 22c is magnetized as an N pole, and since coil B is not excited, the second magnetic pole portion 22b becomes the same N pole as the third magnetic pole portion 22c. As a result, the S pole of the rotor 41 attracts the N poles of the second magnetic pole portion 22b and the third magnetic pole portion 22c, and the N pole of the rotor 41 rotates counterclockwise and rotates approximately 45 degrees to the 45 degree position.

Next, FIG. 23(c) shows a state in which drive waveforms O1 to O4 corresponding to the second drive pulse IP12 are supplied to the step motor 40, and a drive current (not shown) flows from coil terminal O2 to O1, exciting coil A in the direction of the arrow. Also, a drive current (not shown) flows from coil O4 to O3, exciting coil B in the direction of the arrow. As a result, the first magnetic pole portion 22a is magnetized to an S pole, the second magnetic pole portion 22b is magnetized to an N pole, and the third magnetic pole portion 22c is not magnetized because the magnetizations cancel each other out. As a result, the N pole of the rotor 41 and the S pole of the first magnetic pole portion 22a attract each other, and the S pole of the rotor 41 and the N pole of the second magnetic pole portion 22a attract each other, and the N pole of the rotor 41 rotates counterclockwise, rotating approximately 45 degrees from the 45-degree position to the 90-degree position.

Next, FIG. 23(d) shows a state in which the drive waveforms O1 to O4 corresponding to the third initial motion pulse IP13 are supplied to the step motor 40, and the drive current (not shown) is transferred from the coil terminal O4 to O3. current, and coil B is excited in the direction of the arrow. As a result, the second magnetic pole part 22b is magnetized to the north pole, and the third magnetic pole part 22c is magnetized to the south pole, and since the coil A is not excited, the first magnetic pole part 22a becomes the same south pole as the third magnetic pole part 22c. As a result, the N pole of the rotor 41 and the S poles of the first magnetic pole section 22a and the third magnetic pole section 22c attract each other, and the N pole of the rotor rotates counterclockwise, and steady rotation starts from the 90 degree position. Rotate about 45 degrees to the 135 degree position.

As described above, by supplying the step motor 40 with drive waveforms O1 to O4 corresponding to the initial pulse train IP10 consisting of three initial pulses IP11 to IP13, the motor is rotated to the 135 degree position, which is the start position of steady rotation. By rotating the motor by approximately 45 degrees with each of the three initial pulses included in the initial pulse train, the rotor 41 in a stopped state can be reliably rotated to the 135 degree position, which is the start position of steady rotation, improving the probability that steady rotation can be started.

Note that the pulse waveform of the initial pulse train IP is arbitrary as long as the N pole of the rotor 41 is located at the 135 degree position at which steady rotation starts after the output of the initial pulse train IP. For example, the initial pulse train IP10 is configured with only one third initial pulse IP13, or is configured with two initial pulses, either one of the first initial pulse IP11 or the second initial pulse IP12, and the third initial pulse IP13. It may be selected arbitrarily depending on the load of the object to be driven.

Figure 24 is a diagram for explaining the terminal pulse train EP. The terminal pulse train EP generates a drive waveform for maintaining the rotor 41 of the step motor 40 at the static stable point of 0 degrees or 180 degrees.

Figure 24 (a) shows an example of drive waveforms O1 to O4 corresponding to the drive pulse train SP30 and the terminal pulse train EP. The first fixed drive pulse SP31 and the second variable drive pulse SP32 included in the drive pulse train SP30 are the same as those described with reference to Figure 14, so their description will be omitted. Also, like the auxiliary pulse FP described with reference to Figure 16 (a) in the second embodiment, the terminal pulse EP has the role of forcibly driving the N pole of the rotor 41 to the 0 degree position or the static stable point of 180 degrees, so the same pulse as the auxiliary pulse FP is used. In this embodiment, the terminal pulse EP is handled separately from the auxiliary pulse FP. However, since the drive waveform itself is the same as that shown in the auxiliary pulse FP, its description will be omitted. The pulse width of the terminal pulse EP shown in Figure 24 (a) is arbitrary. The drive waveforms O1 to O4 are illustrated as continuous full pulses, but they may be chopper-type drive pulses consisting of multiple fine pulse groups, and can be selected arbitrarily depending on the load of the object to be driven.

Figure 24(b) is a table showing the ON/OFF states of the eight transistors P1 to P4 and N1 to N4 of the driver circuit 60 due to the termination pulse train EP. Figure 24(b) is the same as the ON/OFF states of the transistors P1 to P4 and N1 to N4 due to the auxiliary pulse FP shown in Figure 16(b), so a description is omitted.

Figures 25(a) to (d) are diagrams for explaining the operation of the step motor 40 by the terminal pulse EP shown in Figure 24.

Figure 25 (a) shows the state in which drive waveforms O1 to O4 corresponding to the first fixed drive pulse SP31 are supplied to the step motor 40. In this case, the N pole of the rotor 41 and the S pole of the second magnetic pole portion 22b attract each other, and the S pole of the rotor 41 and the N pole of the first magnetic pole portion 22a attract each other, causing the N pole of the rotor 41 to rotate counterclockwise, rotating approximately 135 degrees from the starting position of steady rotation, 135 degrees, to a position of 270 degrees.

Next, FIG. 25(b) shows a state in which drive waveforms O1 to O4 corresponding to the second variable drive pulse SP32 are supplied to the step motor 40. In this case, the first magnetic pole part 22a and the third magnetic pole part 22c are magnetized to the north pole, and the second magnetic pole part 22b is magnetized to the south pole. As a result, the N pole of the rotor 41 and the S pole of the second magnetic pole section 22b attract each other, and the S pole of the rotor 41 attracts the N poles of both the first magnetic pole section 22a and the third magnetic pole section 22c, so that the rotor The north pole of 41 is further rotated counterclockwise, rotating 45 degrees from the 270 degree position to the 315 degree position.

Next, Figure 25 (c) shows the state in which the drive waveforms O1 to O4 corresponding to the terminal pulse EP are supplied to the step motor 40 upon receiving a drive stop command. In this case, the first magnetic pole portion 22a and the second magnetic pole portion 22b are magnetized to the S pole, and the third magnetic pole portion 22c is magnetized to the N pole. As a result, the S pole of the rotor 41 and the N pole of the third magnetic pole portion 22c attract each other, causing the N pole of the rotor 41 to rotate to the 0 degree position.

Next, Figure 25 (d) shows the state in which the voltage supply to the step motor is cut off after the terminal pulse EP is output. In this case, since neither coil A nor coil B is excited, only the holding torque acts, and the N pole of rotor 41 remains stopped at the statically stable point of 0 degrees.

Note that when outputting the termination pulse EP after outputting the inverted second variable drive pulse SP34 shown in FIG. 16, the coil terminals O1 and O2 and O3 and O4 of the termination pulse EP shown in FIG. It is sufficient to output the replaced drive waveform.

The operation flow in the third embodiment will be described below with reference to FIG. 18, which is shown in the second embodiment.

When the operation starts, the initial pulse train IP output from the initial pulse generation circuit 58 is selected by the pulse selection circuit 56 and output to the driver circuit 60. At this point, due to the output of the initial pulse train IP, the N pole of the rotor 41 is located at 135 degrees, which is the starting position of steady rotation, so that steady driving is possible.

Next, based on ST1 to ST8 shown in Figure 18, the drive pulse train SP30 is output until a stop signal is issued, resulting in steady-state operation.

Next, when a stop signal is issued (ST8: Y), the terminal pulse EP output from the terminal pulse generating circuit 59 is selected by the pulse selection circuit 56 and output to the driver circuit 60. This allows the N pole of the rotor 41 to be stopped at 0 degrees or 180 degrees, which are the static stable points. Even if the output of the terminal pulse EP is stopped, it continues to be stopped at the 0 degree or 180 degree position due to the holding torque.

As described above, according to the step motor drive device 70 of the third embodiment, it is possible to prevent the rotor 41 of the step motor 40 from stepping out when it starts moving from a stopped state and when it is stationary during steady drive, and is Moreover, operation with high drive reliability is possible.

[Modification 1 of the third embodiment]
FIG. 26 is a diagram for explaining a case where the terminal pulse EP is output after the first fixed drive pulse SP31 or the inverted first fixed drive pulse SP33 is output.

Figure 26(a) shows an example of drive waveforms O1 to O4 when a terminal pulse EP is output after a first fixed drive pulse SP31. Figure 26(a) shows the waveforms from Figure 24(a) excluding the drive waveforms O1 to O4 corresponding to the second variable drive pulse SP32, so their explanation is omitted.

FIGS. 26(b) to 26(d) are diagrams for explaining the operation of the step motor 40 according to the termination pulse EP shown in FIG. 26(a).

FIG. 26(b) shows a state in which drive waveforms O1 to O4 corresponding to the first fixed drive pulse SP31 are supplied to the step motor 40. In this case, the north pole of the rotor 41 and the south pole of the second magnetic pole part 22b attract each other, and the south pole of the rotor 41 and the north pole of the first magnetic pole part 22a attract each other, and the north pole of the rotor 41 rotates counterclockwise. Then, it rotates approximately 135 degrees from the steady rotation starting position of 135 degrees to a position of 270 degrees.

Next, Figure 26 (c) shows the state in which the drive waveforms O1 to O4 corresponding to the terminal pulse EP are supplied to the step motor 40 upon receiving a drive stop command. In this case, the first magnetic pole portion 22a and the second magnetic pole portion 22b are magnetized to the S pole, and the third magnetic pole portion 22c is magnetized to the N pole. As a result, the S pole of the rotor 41 and the N pole of the third magnetic pole portion 22c attract each other, causing the N pole of the rotor 41 to rotate to the 0 degree position.

Next, Figure 26(d) shows the state in which the voltage supply to the step motor is cut off after the terminal pulse EP is output. In this case, since neither coil A nor coil B is excited, only the holding torque acts, and the N pole of the rotor 41 continues to stop at the statically stable point of 0 degrees.

It is also possible to output a terminal pulse after outputting the inverted first fixed drive pulse SP33 shown in FIG. 16. In that case, it is sufficient to output a drive waveform in which the coil terminals O1 and O2, and O3 and O4 of the terminal pulse EP shown in FIG. 26(a) are swapped.

In the first modification of the third embodiment, even if the step motor 40 is driven at high speed and large inertia is acting on the rotor 41, after the first fixed drive pulse SP11 or the inverted first fixed drive pulse is output, By outputting the termination pulse EP, braking by the termination pulse EP can be applied from the position where the N pole of the rotor 41 is 90 degrees or 270 degrees, making it easier to stop at the 0 degree or 180 degree position. Is possible.

[Modification 2 of the third embodiment]
Fig. 27 is a diagram for explaining the initial pulse train IP20 in the modified example 2 of the third embodiment. Fig. 27(a) shows an example of drive waveforms O1 to O4 corresponding to the initial pulse train IP20. In the modified example 2 of the third embodiment, rotation detection is performed while the initial pulse train IP20 is being output, and a correction pulse can be output according to the rotation detection result.

The drive waveforms O1 to O4 corresponding to the initial pulse train IP20 shown in FIG. 27(a) are the same as the drive waveforms O1 to O4 corresponding to the initial pulse train IP10 shown in FIG. 22. Here, the initial pulse train IP20 is divided into three pulses, the first initial pulse IP21, the second initial pulse IP22, and the third initial pulse IP23. The lengths of the first initial pulse IP21 and the second initial pulse IP22 are fixed and predetermined. In contrast, the length of the third initial pulse IP23 is variable, and which length is selected based on the result of rotation detection. The pulses are output continuously until it is determined that rotation has occurred. As an example, the length can be selected from five lengths from 1 ms to 5 ms in 1 ms increments, similar to the second variable drive pulse SP32/SP34 in the second embodiment.

FIG. 27(b) is a table showing the ON/OFF states of the 12 transistors P1 to P4, N1 to N4, and TP1 to TP4 of the driver circuit 60 according to the initial pulse train IP20.

The operations of the transistors P1 to P4 and N1 to N4 of the driver circuit 60 for outputting the initial pulses IP21 to IP23 constituting the initial pulse train IP20 are the same as those described with reference to FIG. 22(b). , the explanation is omitted.

The operation of transistors TP1 to TP4 of driver circuit 60, which outputs detection pulse CP, will be explained. Since rotation detection is not performed for the first initial motion pulse IP21 and the second initial motion pulse IP22, transistors TP1 to TP4 are OFF. Next, for the third initial motion pulse IP23, only coil B is excited and coil A is used for rotation detection, so only transistor TP1 is ON and transistors TP2, TP3, and TP4 are OFF.

FIG. 28 is a diagram showing an operation flow in Modification 2 of the third embodiment. The operation flow in the second modification of the third embodiment will be described below with reference to FIG. 28.

When operation starts, the first initial pulse IP21 and the second initial pulse IP22 output from the initial pulse generating circuit 58 are selected by the pulse selection circuit 48 and output to the driver circuit 60 (ST9).

Next, the third initial pulse IP23 output from the initial pulse generating circuit 58 is selected by the pulse selection circuit 56 and output to the driver circuit 60 (ST10).

Next, the detection pulse CP output from the detection pulse generation circuit 54 is selected by the pulse selection circuit 56 and output to the driver circuit 60 every 5 ms after 0.25 ms has elapsed since the output of the third initial pulse IP23. , starts rotation detection (ST11). Since the rotation detection is the same as that described in the second embodiment, the explanation will be omitted.

After starting rotation detection, the timing at which rotation determination is obtained is monitored. First, it is determined whether the detection signal CS has been obtained twice within 0.75 ms from the start of rotation (ST121). If the detection signal CS is obtained twice (ST121: Y), the rotation detection is finished, the output of the detection pulse CP is stopped (ST131), and the width of the initial pulse IP23 is set to 1 ms (ST141). As a result, the output of the third initial pulse IP23 is set to 1 ms, and the series of operations ends.

If the detection signal CS is not obtained twice within 0.75ms from the start of rotation (ST121: N), then it is determined whether the detection signal CS has been obtained twice within 1.75ms after the start of rotation. (ST122). If the detection signal CS is obtained twice (ST122: Y), the rotation detection is finished (ST132), the output of the detection pulse CP is stopped, and the width of the initial pulse SP23 is set to 2 ms (ST142). As a result, the output of the third initial pulse IP23 is set to 2 ms, and the series of operations ends.

If the detection signal CS is not obtained twice within 1.75ms from the start of rotation (ST122: N), then it is determined whether the detection signal CS has been obtained twice within 2.75ms after the start of rotation. (ST123). If the detection signal CS is obtained twice (ST123: Y), the rotation detection is finished (ST133), the output of the detection pulse CP is stopped, and the width of the initial pulse SP23 is set to 3 ms (ST143). As a result, the output of the third initial pulse IP23 is set to 3 ms, and the series of operations ends.

If the detection signal CS is not obtained twice within 2.75 ms from the start of rotation (ST123: N), then it is determined whether the detection signal CS is obtained twice within 3.75 ms from the start of rotation (ST124). If the detection signal CS is obtained twice (ST124: Y), the rotation detection is terminated (ST134), the output of the detection pulse CP is stopped, and the width of the third initial pulse IP23 is set to 4 ms (ST144). As a result, the output of the third initial pulse IP23 is set to 4 ms, and the series of operations is terminated.

If the detection signal CS is not obtained twice within 3.75ms from the start of rotation (ST124: N), then it is determined whether the detection signal CS has been obtained twice within 4.75ms after the start of rotation. (ST125). If the detection signal CS is obtained twice (ST125: Y), the rotation detection is finished (ST135), the output of the detection pulse CP is stopped, and the width of the initial pulse IP23 is set to 5 ms (ST145). As a result, the output of the third initial pulse IP23 is set to 5 ms, and the series of operations ends.

If the detection signal CS is not obtained twice within 4.75 ms from the start of rotation (ST125: N), it is determined that there is no rotation, so rotation detection is terminated (ST136), the output of the first initial pulse IP23 is set to 5 ms (ST146), and the correction pulse FP output from the correction pulse generating circuit 55 is selected by the pulse selection circuit 47 and output to the driver circuit 60 (ST15). Note that the output of the correction pulse FP is as shown in FIG. 16 in the second embodiment, and is a pulse that forcibly drives the N pole of the rotor 41 to the 0 degree or 180 degree position.

When the operation flow shown in FIG. 28 is completed, the N pole of the rotor 41 is at the start position of steady-state drive or at the static stable point after the correction pulse is output, so the motor can be driven in a steady state. After that, it is sufficient to start the operation for driving the motor in a steady state, and it is desirable to operate according to the flow shown in FIG. 18 in the second embodiment, for example.

By mechanically switching the wheel train in the electronic watch 10, the object driven by the step motor 40 is switched between the hands and the oscillating weight, and it can start moving under appropriate conditions according to the amount of inertia of each. Even if the hands or oscillating weight are changed to one with a larger or smaller amount of inertia, it can start moving under appropriate conditions according to the changed amount of inertia. In other words, regardless of the amount of inertia of the object driven by the step motor 40, it can always start moving under appropriate conditions using a common motor drive device. It can also continue to be driven under optimal drive conditions in subsequent operations.

As described above, according to the second variant of the third embodiment, by performing rotation detection while outputting the initial movement pulse IP that assists in starting to move from a stopped state, an appropriate initial movement pulse is output according to the load to be driven and the power supply state, enabling highly reliable operation when starting to move.

10 Electronic watch 20, 50, 70 Step motor drive device 21 Oscillator circuit 22, 52 Control circuit 23, 53 Drive pulse generating circuit 30, 60 Driver circuit 40 Step motor 41 Rotor 54 Detection pulse generating circuit 55 Correction pulse generating circuit 56 Pulse selection circuit 57 Rotation detection judgment circuit 58 Initial pulse generating circuit 59 Terminal pulse generating circuit SP10, SP30 Drive pulse train CP Detection pulse FP Correction pulse IP Initial pulse EP Terminal pulse

Claims (11)

A rotor magnetized with two poles in the radial direction ;
a stator having a first stator magnetic pole portion and a second stator magnetic pole portion provided opposite the rotor, and a third stator magnetic pole portion provided between the first and second stator magnetic pole portions and facing the rotor;
a first coil magnetically coupled to the first stator pole portion and the third stator pole portion ;
a second coil magnetically coupled to the second stator pole portion and the third stator pole portion ;
a drive voltage generating means capable of generating a drive voltage for driving a step motor having the step motor;
the drive voltages include a first drive voltage that is applied to the first coil and the second coil and excites the first stator magnetic pole portion and the second stator magnetic pole portion with polarities different from each other, and a second drive voltage that is applied to either the first coil or the second coil and excites the first stator magnetic pole portion and the second stator magnetic pole portion with polarities different from each other and excites the third stator magnetic pole portion with the same polarity as the first stator magnetic pole portion or the second stator magnetic pole portion,
The driving voltage generating means
applying the drive voltage such that a rotation direction of the rotor caused by the first drive voltage is the same as a rotation direction of the rotor caused by the second drive voltage;
Rotating the rotor by 90 degrees or more using the first driving voltage;
the rotor is rotated 180 degrees by the first driving voltage and the second driving voltage;
the first driving voltage and the second driving voltage are applied alternately and repeatedly to drive the rotor to rotate;
A step motor drive device comprising: The step motor drive device according to claim 1, wherein the first drive voltage rotates the rotor by 115 degrees or more and 150 degrees or less. further comprising steering storage means for storing the polarity value of the rotor;
The steering storage means inverts the polarity value after outputting the second drive voltage ,
3. The step motor drive device according to claim 1, wherein the drive voltage generating means reverses the directions of application of the first drive voltage and the second drive voltage based on the polarity value. a detection pulse generating means capable of generating a detection pulse for detecting the rotation of the rotor;
a rotation detection means for determining whether the rotor is rotating or not based on a detection signal detected by applying a voltage based on the detection pulse to the first coil or the second coil;
The step motor drive device according to any one of claims 1 to 3, further comprising: The time for applying the second driving voltage to the step motor is variable,
the rotation detection means detects the rotation of the rotor while the second drive voltage is being applied;
5. The step motor drive device according to claim 4 , wherein the application time of said second drive voltage being applied is varied based on the detection result of said rotation detection means. The time for applying the first drive voltage to the step motor is variable,
6. The step motor drive device according to claim 4, wherein the application time of the first drive voltage to be applied next time is varied based on the detection result of the rotation detection means. a correction pulse generating means for generating a correction pulse for assisting the rotation of the rotor;
7. The step motor drive device according to claim 4, wherein the correction pulse generating means outputs a voltage corresponding to the correction pulse to the step motor following the second drive voltage when the rotation detection means determines that the rotor is not rotating. a terminal pulse generating means for generating a terminal pulse for stopping the rotation of the rotor;
The step motor drive device according to any one of claims 1 to 7, wherein the terminal pulse generating means outputs a voltage corresponding to the terminal pulse to the step motor after outputting the first drive voltage or the second drive voltage when driving is stopped. further comprising initial motion pulse generating means capable of generating an initial motion pulse to assist the rotor in a stopped state to start moving;
The step according to any one of claims 4 to 8, wherein the initial pulse generation means outputs a voltage according to the initial pulse to the step motor before outputting the first drive voltage at the time of starting driving. Motor drive device. further comprising initial motion pulse generating means capable of generating an initial motion pulse to assist the rotor in a stopped state to start moving;
The initial pulse generation means outputs a voltage corresponding to the initial pulse to the step motor before outputting the first drive voltage at the time of starting driving,
The time for applying the voltage according to the initial pulse to the step motor is variable,
The rotation detection means detects rotation of the rotor during application of the initial motion pulse,
5. The step motor drive device according to claim 4 , wherein a time period during which a voltage corresponding to the initial motion pulse is applied to the step motor is varied based on a detection result of the rotation detecting means. A step motor drive device as described in any one of claims 1 to 10, wherein when a second drive voltage is applied by the drive voltage generating means, the rotor rotates so that the polarity facing the third stator pole portion of the rotor is different from the polarity of the third stator pole portion.

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