JP4619081B2 - Reversible stepping motor - Google Patents

Description

    The present invention relates to a reversible stepping motor capable of normal rotation and reverse rotation, and more particularly to a reversible stepping motor that includes a detection coil and dynamically controls drive pulses.

    Conventionally, a reversible stepping motor capable of normal rotation and reverse rotation has various uses as an output device of a digital device or the like, and has been widely used particularly as a pointer driving device of an electronic timepiece in recent years. One of them is a rotor magnetized with two or more poles in the radial direction, a pair of main magnetic poles provided opposite to each other via the rotor, a sub-magnetic pole provided substantially perpendicular to the main magnetic pole, A double-rotation stepping motor has been proposed comprising a first coil that is magnetically coupled to one of the magnetic poles and the sub-magnetic pole, and a second coil that is magnetically coupled to the other of the main magnetic poles and the sub-magnetic pole (for example, Patent Document 1). Hereinafter, a conventional double-rotation step motor will be described from Patent Document 1 with reference to the drawings.

    FIG. 11A is a schematic diagram showing the structure of a conventional double-rotation step motor. Reference numeral 101 denotes a rotor, which is a cylindrical magnet with two poles magnetized in the radial direction. Reference numerals 102 and 103 denote a pair of main magnetic poles provided opposite to each other, and reference numeral 104 denotes a sub magnetic pole provided substantially perpendicular to the main magnetic pole. The rotor opposing angle α of the sub magnetic pole is smaller than the rotor opposing angle of the main magnetic poles 102 and 103. Reference numerals 105 and 106 denote two coils. The coil 105 is magnetically connected to the main magnetic pole 103 and the sub magnetic pole 104, and the coil 106 is magnetically connected to the main magnetic pole 102 and the sub magnetic pole 104. The winding terminals 107, 108, 109, 110 of the two coils 105, 106 are all connected to a drive circuit described later.

    FIG. 11B is an example of a conventional drive circuit. An electronic circuit 120 outputs drive pulses P101, P102, P103, and P104. The inverters 121 and 122 convert the driving pulses P101 and P104 into electric power, respectively, and supply them to the winding terminals 108 and 109 of the coils 105 and 106, respectively. The inverter 123 includes a P-channel transistor 123a (hereinafter abbreviated as P-Tr) and an N-channel transistor 123b (hereinafter abbreviated as N-Tr). The gates are separated, and drive pulses P102 and P103 are input, respectively. . The output of the inverter 123 is connected to the winding terminals 107 and 110 of the coils 105 and 106.

    Next, based on FIG. 12, the drive pulses P105 and P106 supplied to the respective winding terminals 107 to 110 of the coils 105 and 106, and the rotational operation of the rotary step motor driven by the drive pulses P105 and P106 are shown. explain. In FIG. 12, timing a is a timing at which the drive pulse P <b> 105 in the positive direction is supplied only to the coil 105. At the timing a, as shown in the figure, the main magnetic pole 103 of the step motor is excited to the N pole, the main magnetic pole 102 and the sub magnetic pole 104 are excited to the S pole, and the rotor 101 starts to rotate in the right direction. Next, timing b is a timing at which drive pulses P105 and P106 in the positive direction are supplied to both the coil 105 and the coil 106. At the timing b, as shown in the figure, the main magnetic pole 103 of the step motor is excited to the N pole, the main magnetic pole 102 is excited to the S pole, and the sub magnetic pole 104 is de-energized so that a strong magnetic pole does not appear. The rotation is continued for one step (180 degrees). Next, in order to further rotate to the right by one step from this state, the polarity of the drive pulses P105 and P106 may be reversed and supplied to the coils 105 and 106 as indicated by timing c and timing d.

Next, the timing e is a timing at which the drive pulse P106 in the plus direction is supplied only to the coil 106. At the timing e, as shown in the figure, the main magnetic pole 103 of the step motor.
The sub magnetic pole 104 is excited to the N pole, the main magnetic pole 102 is excited to the S pole, and the rotor 101 starts to rotate leftward. Next, the timing f is a timing at which drive pulses P105 and P106 in the positive direction are supplied to both the coil 105 and the coil 106. At the timing f, as shown in the figure, the main magnetic pole 103 of the step motor is excited to the N pole, the main magnetic pole 102 is excited to the S pole, and the sub magnetic pole 104 is de-energized and no strong magnetic pole appears. The rotation is continued for one step (180 degrees). Next, in order to further rotate left one step from this state, the polarity of the drive pulses P105 and P106 may be reversed and supplied to the coils 105 and 106 as indicated by timing g and timing h.

    As described above, according to the prior art of Patent Document 1, it is possible to easily realize an ultra-compact double-rotating step motor suitable for a small portable device typified by an analog electronic wristwatch. Moreover, since both rotation control is possible by the waveform of the drive pulse supplied to the two coils, a double rotation step motor having a simple drive circuit and advantageous in cost can be realized.

Japanese Examined Patent Publication No. 2-16679 (1st page-2nd page, Fig. 1)

    However, since the proposal of the above-mentioned patent document 1 uses a fixed pulse system for the drive pulse supplied to the coil, the function of adjusting the drive pulse against disturbances such as motor load fluctuations, power supply voltage fluctuations, temperature changes, and vibrations. Therefore, for example, when the load on the motor becomes heavy, there is a problem in the reliability of the motor drive such that the drive torque is insufficient and the motor drive fails. In addition, when the motor is moving with a light load, there is a problem that since it is a fixed pulse system, more torque than necessary is supplied, driving efficiency is poor, and low power consumption is difficult. In addition, in an electronic timepiece, high-speed driving such as fast-forwarding a hand is required, but there is a problem in that it is difficult to realize quick high-speed driving because there is a problem in reliability of motor driving.

    The object of the present invention is to solve the above-mentioned problems, reversible stepping that realizes stable motor driving and is reliable and capable of high-speed driving against disturbances such as motor load fluctuations, power supply voltage fluctuations, temperature changes, and vibrations. It is to provide a motor.

    In order to solve the above problems, the reversible stepping motor of the present invention employs the following configuration.

    The reversible stepping motor of the present invention includes a rotor magnetized in at least two poles in the radial direction, first and second stator magnetic pole portions provided substantially opposite to each other via the rotor, and the first and second A third stator magnetic pole portion provided between the stator magnetic pole portions and facing the rotor; the first stator magnetic pole portion; the first coil magnetically coupled to the third stator magnetic pole portion; Two stator magnetic pole portions, a second coil magnetically coupled to the third stator magnetic pole portion, and drive means for outputting a drive pulse for driving the first coil and the second coil, Detection for detecting an induced voltage generated according to the rotation of the rotor while the driving means is driving one of the first coil or the second coil while the other of the first coil or the second coil is being driven. Used as a coil The features.

The reversible stepping motor of the present invention uses the other one of the first coil or the second coil as a detection coil for detecting the induced voltage while driving one of the first coil or the second coil. The rotor rotation angle can be grasped against disturbances such as load fluctuations, power supply voltage fluctuations, temperature changes and vibrations, and stable motor driving can be realized.

    The driving pulse for driving the first coil or the second coil is a first driving pulse, a first driving pulse and a second driving pulse, or a first driving pulse, a second driving pulse, and a third driving pulse. And an inversion driving pulse obtained by inverting the driving current of each driving pulse.

    Accordingly, the driving pulse for driving the first coil or the second coil is the first driving pulse, the first driving pulse and the second driving pulse, or the first driving pulse, the second driving pulse, and the third driving pulse. Therefore, the drive pulse can be optimized according to the motor specifications and the motor drive environment, and a highly reliable motor drive can be realized.

    In addition, the driving means includes a first or second stator provided substantially opposite to the current direction of the driving pulse for driving the first coil or the second coil, which is magnetically coupled to the driving coil. Control is performed so that one of the magnetic pole portions and the third stator magnetic pole portion are excited in a direction to separate the rotor.

    Thus, the current direction of the drive pulse for driving the first coil or the second coil is changed so that the first or second stator magnetic pole portion and the third stator magnetic pole portion magnetically coupled to the drive coil are the rotor. The other detection coil of the first coil or the second coil is arranged in the direction in which the magnetic flux generated by the rotor is drawn, and as a result, the detection coil is controlled. The level of the induced voltage generated at the time increases, and the detection accuracy of the induced voltage can be improved.

    In addition, the driving means sets at least one coil terminal of the first coil or the second coil used as the detection coil to be in a high resistance state, and detects the induced voltage at the terminal in the high resistance state. A detection means is provided. Furthermore, a predetermined voltage is applied to the other coil terminal of the terminal in the high resistance state.

    Thus, the driving means includes at least one terminal of the first coil or the second coil used as the detection coil in a high resistance state, and includes voltage detection means for detecting an induced voltage at the terminal, and the high resistance state. A predetermined voltage is applied to the other coil terminal of the terminal, so that an induced voltage generated in the detection coil can be detected efficiently, and a reversible stepping motor that can grasp the rotation angle of the rotor with high accuracy can be realized.

    The predetermined voltage applied to the other terminal of the first coil or the second coil is approximately ½ of the power supply voltage.

    Thereby, since the predetermined voltage applied to the other terminal of the first coil or the second coil is approximately ½ of the power supply voltage, it is induced in one terminal of the first coil or the second coil. The induced voltage is generated in the plus / minus direction centered on approximately half of the power supply voltage. As a result, the dynamic range of the induced voltage is widened, and the detection accuracy of the induced voltage can be improved. .

    The driving means drives the first coil or the second coil when the voltage detecting means detects that the induced voltage generated by the detection coil has reached a predetermined voltage. The drive pulse is stopped to dynamically control the first drive pulse width, and immediately after the output of the first drive pulse is finished, the second drive pulse, or the second drive pulse and the third drive pulse are continued. Output.

    Thus, when the voltage detecting means for detecting the induced voltage detects the predetermined voltage, the driving means stops the first driving pulse for driving the first coil or the second coil and increases the first driving pulse width. Since dynamic control is performed, a stable motor drive can be realized against disturbances such as motor load fluctuations, power supply voltage fluctuations, temperature changes and vibrations, and a low power consumption reversible stepping motor can be provided. Also, the second drive pulse, or the second drive pulse and the third drive pulse output after the output of the first drive pulse is finished, pulls the rotor further to rotate it, and the rotor rotates one step (180 degrees) or more. Therefore, the rotational torque of the rotor increases and the reliability of the rotor rotation can be improved.

    The voltage detection means for detecting the induced voltage has voltage hysteresis means or time hysteresis means for the predetermined voltage.

    Thus, since the voltage detection means has voltage hysteresis means or time hysteresis means, even if electrical noise is superimposed on the induced voltage, malfunction of voltage detection is prevented by the hysteresis characteristic, and the detection accuracy of the induced voltage is improved. Can be improved.

    Further, the drive means is characterized in that the drive cycle of the drive pulse is a fixed drive cycle, and the pulse width of the first drive pulse is secured up to a maximum pulse width determined by the drive cycle of the drive pulse.

    As a result, the pulse width of the first drive pulse is secured up to the maximum pulse width determined by the drive cycle of the drive pulse, so that a reversible stepping motor with high reliability against disturbance such as load fluctuation can be provided. Further, since the driving cycle is fixed, the step feed of the motor can be always kept constant.

    Further, the driving means drives the driving pulse in accordance with a change in the first driving pulse width caused by dynamically controlling the pulse width of the first driving pulse with a driving period of the driving pulse as a variable driving period. The period is variable.

  As a result, the drive cycle of the drive pulse becomes a variable drive cycle in accordance with the dynamic control of the pulse width of the first drive pulse, so that the drive torque that is always required for motor load fluctuations, power supply voltage fluctuations, etc. Therefore, it is possible to provide a reversible stepping motor that achieves a highly reliable motor drive.

    Further, the drive means is provided with a predetermined mask period for masking a detection signal from the voltage detection means in an induced voltage detection period of the first coil or the second coil that is used as a detection coil. .

    As a result, a predetermined mask period is provided in the induced voltage detection period of the first coil or the second coil that is the detection coil, so that malfunction of the voltage detection means due to electrical noise generated in the induced voltage within the mask period. The reliability of the dynamic control of the drive pulse can be improved.

    Further, the driving means performs chopper driving on the first driving pulse for driving the first coil or the second coil during the mask period.

Thereby, during the mask period, the first driving pulse for driving the first coil or the second coil is chopper driven, so that low power consumption of motor driving can be realized. In addition, when the first drive pulse is chopper-driven, electrical noise due to chopper driving is superimposed on the induced voltage generated in the detection coil. However, since the chopper driving period is a mask period for detecting the induced voltage, the electrical noise is not detected. The reliability of dynamic control of drive pulses can be maintained.

    Further, the driving means sets the first driving pulse for driving the first coil or the second coil as a full driving pulse in a period other than the mask period.

    As a result, the first drive pulse for driving the first coil or the second coil is a full drive pulse except during the mask period, and therefore there is very little possibility of electrical noise occurring in the induced voltage outside the mask period. Thus, it is possible to prevent malfunction of the voltage detecting means and improve the reliability of dynamic control of the drive pulse.

    Further, the second drive pulse and the third drive pulse have a drive energy smaller than that of the first drive pulse.

    As a result, since the second drive pulse and the third drive pulse have smaller drive energy than the first drive pulse, it is possible to prevent an excessive braking effect from being applied to the rotor and improve the reliability of the rotor rotation. I can do it.

    The drive means may reduce drive energy by chopper-driving the second drive pulse and the third drive pulse.

    As a result, the second drive pulse and the third drive pulse are chopper driven, so that the drive energy of the second drive pulse and the third drive pulse is smaller than that of the first drive pulse. It is possible to prevent the effect from being applied, improve the reliability of the rotor rotation, and realize low power consumption of the motor drive.

    Further, the drive means and the voltage detection means have the same functions and operations in high-speed forward rotation drive and high-speed reverse drive of the motor.

    As a result, the drive means and voltage detection means have the same functions and operations even when the motor is driven at high speed. Stable motor drive can be realized against disturbances such as fluctuations, temperature changes and vibrations.

    In addition, the magnetic saturation portion is formed by separating the coupling portion surrounding the rotor of the first, second, and third stator magnetic pole portions, and is made of a non-magnetic material to fix the magnetic saturation portion to each other. The support plate and the first, second, and third stator magnetic pole portions are mechanically fixed by fixing means.

    As a result, each of the first, second, and third stator magnetic pole portions is magnetically separated by the magnetic saturation portion, so that each stator magnetic pole portion can be efficiently excited to generate strong S and N poles. In addition, the driving torque for the rotor is increased, and a reversible stepping motor with sufficient power can be provided. In addition, since leakage of magnetic flux between the stator magnetic pole portions is reduced, the level of the induced voltage induced in the detection coil is increased, the S / N ratio is improved, and the detection accuracy of the induced voltage can be improved. .

    Further, the fixing means is welding.

    As a result, since the fixing means for connecting the stator magnetic pole portions is welding, the stator magnetic pole portions can be connected with a strong mechanical strength, and a highly reliable reversible stepping motor without change over time can be provided.

    As described above, according to the present invention, while one of the first coil or the second coil is being driven, the other of the first coil or the second coil is detected according to the rotation angle of the motor. Therefore, it is possible to provide a reversible stepping motor that grasps the rotation angle of the rotor against disturbances such as motor load fluctuations, power supply voltage fluctuations, temperature changes, and vibrations, and realizes stable motor driving.

    Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing the structure of a reversible stepping motor according to a first embodiment of the present invention. FIG. 2 is a circuit block diagram showing an example of a drive circuit for driving the reversible stepping motor according to the first embodiment of the present invention. FIG. 3 is a timing chart of drive pulses for normal rotation of the reversible stepping motor according to the first embodiment of the present invention, and an explanatory diagram showing the rotation operation of the rotor. FIG. 4 is a timing chart of drive pulses for reversing the reversible stepping motor according to the first embodiment of the present invention and an explanatory diagram showing the rotation operation of the rotor. FIG. 5 is a timing chart for explaining the induced voltage generated in the detection coil of the reversible stepping motor of Embodiment 1 of the present invention and the operation of the voltage detection means. FIG. 6 is a timing chart for explaining another form of induced voltage and drive pulse generated in the detection coil of the reversible stepping motor according to the first embodiment of the present invention. FIG. 7 is a timing chart illustrating the high-speed driving operation of the reversible stepping motor according to the first embodiment of the present invention. FIG. 8 is a timing chart of drive pulses for normal rotation of the reversible stepping motor according to the second embodiment of the present invention and an explanatory diagram showing the rotation operation of the rotor. FIG. 9 is a timing chart of drive pulses for reversing the reversible stepping motor according to the second embodiment of the present invention and an explanatory diagram showing the rotation operation of the rotor. FIG. 10 is a schematic diagram showing the structure of a reversible stepping motor according to a third embodiment of the present invention.

    The configuration of the reversible stepping motor of the present invention will be described based on FIG. In FIG. 1, reference numeral 1 denotes a reversible stepping motor according to a first embodiment of the present invention. Reference numeral 2 denotes a rotor, which is composed of a cylindrical magnet in which S and N poles are magnetized in the radial direction. Reference numerals 3 and 4 denote a first stator magnetic pole part and a second stator magnetic pole part provided opposite to each other with the rotor 2 interposed therebetween. Reference numeral 5 denotes a third stator magnetic pole portion provided between the first and second stator magnetic pole portions so as to face the rotor 2. The material of these stator magnetic pole portions is preferably a soft magnetic material such as permalloy. 6 and 7 are two coils, the coil 6 is magnetically coupled to the first stator magnetic pole part 3 and the third stator magnetic pole part 5, and the coil 7 is connected to the second stator magnetic pole part 4 and the third stator magnetic pole part 5. Magnetically coupled. In addition, coil terminals 6a and 6b of the coil 6 are respectively connected to terminals O1 and O2 of a drive circuit to be described later, and coil terminals 7a and 7b of the coil 7 are respectively connected to terminals O3 and O4 of a drive circuit to be described later. Reference numerals 8a, 8b, and 8c denote magnetic flux saturation portions, which are located at the most sandwiched portions where the first stator magnetic pole portion 3, the second stator magnetic pole 4 and the third stator magnetic pole portion 5 are coupled to each other. In comparison, magnetic saturation is likely to occur and the magnetic resistance is large. For this reason, since the magnetic flux generated by the coils 6 and 7 is saturated by the magnetic flux saturation portions 8a, 8b and 8c and the passage of the magnetic flux is prevented, each of the first, second and third stator magnetic pole portions 3 to 3 is prevented. 5 has a strong magnetic pole.

Next, an outline of a circuit configuration of a drive circuit as drive means for driving the reversible stepping motor 1 will be described with reference to FIG. Reference numeral 11 denotes a control circuit that controls the entire drive circuit, and is constituted by a microcomputer or the like. Reference numeral 12 denotes an inverter, which is composed of a P-Tr 12a and an N-Tr 12b. The gate terminals of the P-Tr 12a are separated from each other. The drive control signal P2, which is an output from the control circuit 11, is connected to the gate terminal of the N-Tr 12b. Further, the source terminal of the P-Tr 12a is connected to the positive power supply VDD, and N-T
The source terminal of r12b is connected to the negative power supply VSS. The inverter 12 outputs a drive pulse O1 from a terminal O1.

    Reference numeral 13 denotes an inverter, which is composed of a P-Tr 13a and an N-Tr 13b. The gate terminals of the P-Tr 13a are separated, and a drive control signal P3, which is an output from the control circuit 11, is supplied to the gate terminal of the P-Tr 13a. The drive control signal P4, which is an output from the control circuit 11, is connected to the gate terminal of the N-Tr 13b. The source terminal of the P-Tr 13a is connected to the positive power supply VDD, and the source terminal of the N-Tr 13b is connected to the negative power supply VSS. The inverter 13 outputs a drive pulse O2 from the terminal O2. Reference numeral 14 denotes an inverter, which is composed of a P-Tr 14a and an N-Tr 14b. The gate terminals of the P-Tr 14a are separated from each other. The drive control signal P6 that is an output from the control circuit 11 is connected to the gate terminal of the N-Tr 14b. The source terminal of the P-Tr 14a is connected to the positive power supply VDD, and the source terminal of the N-Tr 14b is connected to the negative power supply VSS. The inverter 14 outputs a drive pulse O3 from a terminal O3.

    Reference numeral 15 denotes an inverter, which is composed of a P-Tr 15a and an N-Tr 15b. The gate terminals are separated from each other, and a drive control signal P7, which is an output from the control circuit 11, is supplied to the gate terminal of the P-Tr 15a. The drive control signal P8 that is an output from the control circuit 11 is connected to the gate terminal of the N-Tr 15b. The source terminal of the P-Tr 15a is connected to the positive power supply VDD, and the source terminal of the N-Tr 15b is connected to the negative power supply VSS. The inverter 15 outputs a drive pulse O4 from the terminal O4. Reference numeral 16 denotes a voltage detection circuit as voltage detection means, which is provided with a hysteresis circuit 16a as voltage hysteresis means or time hysteresis means. The voltage detection circuit 16 receives the drive pulse O1, detects an induced voltage generated in the drive pulse O1, and outputs a detection signal P9.

    Reference numeral 17 denotes a voltage detection circuit as voltage detection means similar to the voltage detection circuit 16, and includes a hysteresis circuit 17a as voltage hysteresis means or time hysteresis means. The voltage detection circuit 17 receives the drive pulse O4, detects an induced voltage generated in the drive pulse O4, and outputs a detection signal P10. An AND circuit 18 receives the mask signal P11 output from the control circuit 11 and the detection signal P9, and outputs a dynamic control signal P12. An AND circuit 19 inputs the mask signal P11 and the detection signal P10 and outputs a dynamic control signal P13.

    An AND circuit 20 receives a drive control signal P3 and a signal obtained by inverting the drive control signal P4 by the inverter 21 and outputs a bias control signal P14. Reference numeral 22 denotes a bias circuit, which outputs a bias voltage P15 that is about ½ of the power supply voltage. An analog switch 23 has a function of inputting the bias control signal P14 to the control terminal C and supplying or blocking the bias voltage P15 to the drive pulse O2. An AND circuit 24 inputs a signal obtained by inverting the drive control signal P5 and the drive control signal P6 by the inverter 25, and outputs a bias control signal P16. A bias circuit 26 outputs a bias voltage P17 that is about ½ of the power supply voltage. An analog switch 27 has a function of inputting the bias control signal P16 to the control terminal C and supplying or cutting off the bias voltage P17 to the drive pulse O3.

Next, the operation of the drive circuit as the drive means shown in FIG. 2 and the rotation operation of the rotor 2 of the reversible stepping motor 1 in the normal rotation direction will be described with reference to FIG. For easy understanding, each operation will be described in six stages from timing A to timing F. In FIG. 3, the timing A is a non-excited state, no drive pulse is applied to the coils 6 and 7, the drive pulses O1 to O4 are both logic “1” (VDD), and the first stator magnetic pole portion. 3, the second stator magnetic pole part 4 and the third stator magnetic pole part 5 are not excited, and the rotor 2 is stopped in the initial state with the N pole on the top and the S pole on the bottom. Here, the control circuit 11 outputs all the drive control signals P1 to P8 as logic “0” in order to set all the drive pulses O1 to O4 to logic “1”.

    Next, timing B is the timing at which the first drive pulse is output to the coil 7, and since the control circuit 11 sets the drive control signals P5 and P6 to logic "0", the drive pulse O3 becomes logic "1". Further, since the control circuit 11 sets the drive control signals P7 and P8 to logic "1", the drive pulse O4 is set to logic "0" (VSS), and a drive current flows from the coil terminal 7a of the coil 7 to the coil terminal 7b. . As a result, the coil 7 is a drive coil, the second stator magnetic pole portion 4 is excited to the N pole, the first stator magnetic pole portion 3 and the third stator magnetic pole portion 5 are excited to the S pole, and the rotor 2 is moved to the left ( Rotation is started at 90 degrees or more. Here, the second stator magnetic pole portion 4 is excited in a direction to separate the N pole of the rotor 2 (that is, excited to the N pole), and the third stator magnetic pole portion 5 is excited in a direction to separate the S pole of the rotor 2. (In other words, excitation to the S pole).

    At timing B, the control circuit 11 sets the drive control signal P1 to logic “1”, the drive control signal P2 to logic “0”, and turns off both the P-Tr 12a and N-Tr 12b of the inverter 12 to drive pulses. Let O1 be in a high resistance state. Similarly, the control circuit 11 sets the drive control signal P3 to logic “1”, the drive control signal P4 to logic “0”, turns off both the P-Tr 13a and N-Tr 13b of the inverter 13 and sets the drive pulse O2 to the high resistance state. To do. Here, since the AND circuit 20 receives the drive control signal P3 and the inverted output of the drive control signal P4, the output bias control signal P14 becomes logic “1”, and the analog switch 23 is turned on, and the bias The bias voltage P15, which is the output of the circuit 22, is supplied to the drive pulse O2 in the high resistance state, so that the drive pulse O2 has the same potential as the bias voltage P15. That is, at the timing B, the drive pulse O2 is set to a voltage of about ½ VDD equal to the potential of the bias voltage P15, and the drive pulse O1 is set to a high resistance state.

    Here, since the drive pulses O1 and O2 are respectively connected to the coil terminals 6a and 6b of the coil 6, the coil terminal 6a is in a high resistance state, the coil 6b is about 1/2 VDD, and the coil 6 is The detection coil detects the induced voltage. That is, when the rotor 2 starts to rotate by the coil 7 that is a drive coil, a change in magnetic flux generated by the rotation of the rotor 2 is transmitted to the coil 6 via the first stator magnetic pole portion 3 and the third stator magnetic pole portion 5, An induced voltage generated by the change of magnetic flux appears between the coil terminal 6a and the coil terminal 6b of the coil 6. Here, as described above, the drive pulse O2 connected to the coil terminal 6b has a potential equal to the bias voltage P15 (that is, about ½ VDD), and therefore is connected to the coil terminal 6a which is the other terminal. In the drive pulse O1, an induced voltage is generated with reference to the potential of the drive pulse O2 (that is, the bias voltage P15). That is, the induced voltage is uniformly generated in the plus direction or the minus direction according to the direction of change of the magnetic flux around the potential of the bias voltage P15, so that an induced voltage having a wide dynamic range can be obtained.

Here, the voltage detection circuit 16 receives the drive pulse O1, detects the induced voltage, and outputs the detection signal P9 when the induced voltage reaches a predetermined voltage. The AND circuit 18 receives the detection signal P9 and the mask signal P11, performs a logical AND, and outputs a dynamic control signal P12. When the dynamic control signal P12 is input, the control circuit 11 immediately ends the first drive pulse at the timing B. The predetermined voltage detected by the voltage detection circuit 16 is preferably a voltage substantially equal to the bias voltage P15, and the rotor 2 is about 90 degrees from the initial non-excitation state in the vicinity of the induced voltage reaching the bias voltage P15. The position is rotated. Here, since the end of the first drive pulse is slightly delayed from when the induced voltage reaches the bias voltage P15, the rotation of the rotor 2 reaches 90 degrees + α from the initial state, and at the timing B shown in FIG. The rotational position of the rotor 2 indicates the rotational position at the end of the timing B.

    Here, for example, when the load on the motor is light, the rotor 2 rotates quickly, so the time from the start of timing B as the first drive pulse until the induced voltage reaches the bias voltage P15 is shortened. The drive time of the first drive pulse is adjusted to be short. Further, when the motor load is heavy, the rotor 2 rotates slowly, so that the time until the induced voltage reaches the bias voltage P15 after the start of the timing B, which is the first drive pulse, becomes long. As a result, the first The drive time of the drive pulse is adjusted to be long. That is, the pulse width of the first drive pulse is dynamically controlled by the control circuit 11 according to the rotation angle of the rotor 2 where the induced voltage appears. The pulse width of the first drive pulse is often controlled in the range of 2 mS to 4 mS in the normal state.

    Next, the timing C is a timing at which the second drive pulse is output immediately after the end of the first drive pulse, and the control circuit 11 outputs the drive control signals P1, P2 and the drive control signals P7, P8 in a short time. 1 "and logic" 0 "are repeated, and the drive pulses O1 and O4 are chopper driven as shown. Further, the control circuit 11 outputs the drive control signals P3, P4, P5, and P6 as logic “0”, and sets the drive pulses O2 and O3 to logic “1”. Thereby, a chopper driving current flows from the coil terminal 6b of the coil 6 toward the coil terminal 6a, and similarly, a chopper driving current flows from the coil terminal 7a of the coil 7 toward the coil terminal 7b.

    As a result, the two coils 6 and 7 both function as drive coils, the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 are excited to the N pole, and the third stator magnetic pole portion 5 is excited to the S pole. The Thus, the S pole of the rotor 2 is attracted by the N pole of the first stator magnetic pole portion 3, and the N pole of the rotor 2 is separated by the N pole of the first stator magnetic pole portion 3 and the third stator magnetic pole portion 5 Since the rotor 2 is attracted by the S pole, the rotor 2 continues to rotate further in the left direction (forward rotation), and rotates one step (ie, 180 degrees) from the non-excited initial state at timing A. When the rotor 2 rotates by one step, the S pole of the rotor 2 is attracted from both by the N poles of the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 to be braked, and the N pole of the rotor 2 is The brake is applied by being attracted to the S pole of the third stator magnetic pole portion 5, and the rotor 2 stops and stabilizes after one step rotation.

    Next, the period of the timing D is a non-excitation period again, the drive pulses O1 to O4 are both set to logic “1”, the drive current does not flow through the coils 6 and 7, and the rotor 2 is kept stopped. The For example, assuming that the reversible stepping motor is driven step by step per second, the period of timing D is a time obtained by subtracting the periods of timing B and timing C from 1 second.

    Next, the operation of rotating the rotor 2 one step further from the position of the timing D in the left direction (forward rotation) will be described. Timing E is the timing at which the inverted first drive pulse is output to the coil 7. Since the control circuit 11 sets the drive control signals P5 and P6 to logic "1", the drive pulse O3 becomes logic "0". Since the control circuit 11 sets the drive control signals P7 and P8 to logic “0”, the drive pulse O4 is set to logic “1”, and a drive current flows from the coil terminal 7b of the coil 7 to the coil terminal 7a. As a result, the coil 7 is made a drive coil, the second stator magnetic pole portion 4 is excited to the S pole, the first stator magnetic pole portion 3 and the third stator magnetic pole portion 5 are excited to the N pole, and the rotor 2 is turned leftward again. Rotation is started at (forward rotation), and it is rotated 90 degrees or more from the position of the timing D. Here, the second stator magnetic pole portion 4 is excited in a direction to separate the south pole of the rotor 2 (that is, excited to the south pole), and the third stator magnetic pole portion 5 is excited in a direction to separate the north pole of the rotor 2. (In other words, excitation to the N pole).

    At timing E, the control circuit 11 sets the drive control signal P1 to logic “1”, the drive control signal P2 to logic “0”, and turns off both the P-Tr 12a and N-Tr 12b of the inverter 12 to drive pulses. Let O1 be in a high resistance state. Similarly, the control circuit 11 sets the drive control signal P3 to logic “1”, the drive control signal P4 to logic “0”, turns off both the P-Tr 13a and N-Tr 13b of the inverter 13 and sets the drive pulse O2 to the high resistance state. To do. Here, since the AND circuit 20 receives the drive control signal P3 and the inverted output of the drive control signal P4, the output bias control signal P14 becomes logic “1”, and the analog switch 23 is turned on, and the bias The bias voltage P15, which is the output of the circuit 22, is supplied to the drive pulse O2 in the high resistance state, so that the drive pulse O2 has the same potential as the bias voltage P15. That is, at the timing E, the drive pulse O2 is set to a voltage of about ½ VDD that is equal to the potential of the bias voltage P15, and the drive pulse O1 is set to a high resistance state.

    Here, since the drive pulses O1 and O2 are respectively connected to the coil terminals 6a and 6b of the coil 6, the coil terminal 6a is in a high resistance state, the coil 6b is about 1/2 VDD, and the coil 6 is The detection coil detects the induced voltage. That is, when the rotor 2 starts to rotate by the coil 7 that is a drive coil, a change in magnetic flux generated by the rotation of the rotor 2 is transmitted to the coil 6 via the first stator magnetic pole portion 3 and the third stator magnetic pole portion 5, An induced voltage generated by the change of magnetic flux appears between the coil terminal 6a and the coil terminal 6b of the coil 6. Here, as described above, the drive pulse O2 connected to the coil terminal 6b has a potential equal to the bias voltage P15 (that is, about ½ VDD), and therefore is connected to the coil terminal 6a which is the other terminal. In the drive pulse O1, an induced voltage is generated with reference to the potential of the drive pulse O2 (that is, the bias voltage P15). That is, the induced voltage is uniformly generated in the plus direction or the minus direction according to the direction of change of the magnetic flux around the potential of the bias voltage P15, so that an induced voltage having a wide dynamic range can be obtained. At the timing B, the magnetic pole of the rotor 2 causing the magnetic flux change is the N pole. However, the magnetic pole of the rotor 2 causing the magnetic flux change at the timing E is the S pole. Thus, the polarity of the induced voltage is reversed, and the induced voltage is generated on the minus side with reference to the bias voltage P15.

    Here, the voltage detection circuit 16 receives the drive pulse O1, detects the induced voltage, and outputs the detection signal P9 when the induced voltage reaches a predetermined voltage. The AND circuit 18 receives the detection signal P9 and the mask signal P11, performs a logical AND, and outputs a dynamic control signal P12. When receiving the dynamic control signal P12, the control circuit 11 immediately ends the inverted first drive pulse at the timing E. The predetermined voltage detected by the voltage detection circuit 16 is preferably a voltage substantially equal to the bias voltage P15 as in the case of the timing B, and the rotor 2 is moved from the non-excited state at the timing D in the vicinity where the induced voltage reaches the bias voltage P15. The position is rotated about 90 degrees. Here, since the end of the inverted first drive pulse is slightly delayed from the time when the induced voltage reaches the bias voltage P15, the rotation of the rotor 2 reaches 90 ° + α from the position of the timing D, and the timing shown in FIG. The rotational position of the rotor 2 at E indicates the rotational position at the end of the timing E.

Here, for example, when the load on the motor is light, the rotor 2 rotates quickly, so the time from the start of the timing E, which is the inverted first drive pulse, until the induced voltage reaches the bias voltage P15 is shortened. The drive time of the inverted first drive pulse is adjusted to be short. Further, when the load on the motor is heavy, the rotor 2 rotates slowly, so that the time until the induced voltage reaches the bias voltage P15 after the start of the timing E which is the inverted first drive pulse becomes long, and as a result, the inversion The drive time of the first drive pulse is adjusted to be long. In other words, the pulse width of the inverted first drive pulse is dynamically controlled by the control circuit 11 according to the rotation angle of the rotor 2 where the induced voltage appears. Note that the pulse width of the inverted first drive pulse is controlled in the range of 2 mS to 4 mS in the normal state as in the case of the above-described first drive pulse. However, in FIG. The pulse width of the pulse is shorter than the first drive pulse at timing B, and indicates that the first drive pulse and the inverted first drive pulse are dynamically controlled by a load variation of the motor.

    Next, timing F is a timing at which the inverted second drive pulse is output immediately after the end of the inverted first drive pulse, and the control circuit 11 sends the drive control signals P3 and P4 and the drive control signals P5 and P6 in a short time. The logic “1” and the logic “0” are repeated, and the drive pulses O2 and O3 are chopper driven as shown in the figure. Further, the control circuit 11 outputs the drive control signals P1, P2, P7, and P8 as logic “0”, and sets the drive pulses O1 and O4 to logic “1”. Thereby, a chopper drive current flows from the coil terminal 6a of the coil 6 toward the coil terminal 6b, and similarly, a chopper drive current flows from the coil terminal 7b of the coil 7 toward the coil terminal 7a.

    As a result, the two coils 6 and 7 both function as drive coils, the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 are excited to the S pole, and the third stator magnetic pole portion 5 is excited to the N pole. The Thereby, the N pole of the rotor 2 is attracted by the S pole of the first stator magnetic pole portion 3, and the S pole of the rotor 2 is separated by the S pole of the first stator magnetic pole portion 3 and the third stator magnetic pole portion 5 Since it is attracted by the N pole, the rotor 2 further continues to rotate leftward (forward rotation), and rotates one step (ie, 180 degrees) from the non-excited state at timing D. When the rotor 2 rotates by one step, the N pole of the rotor 2 is attracted from both by the S poles of the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 to be braked, and the S pole of the rotor 2 is The brake is applied by being attracted to the N pole of the third stator magnetic pole portion 5, and the rotor 2 stops and stabilizes after one step rotation. As described above, by repeating the timing A to the timing F, the rotor 2 rotates leftward (forward rotation) by two steps (that is, 360 degrees).

    At the timing B, the second stator magnetic pole portion 4 is excited in the direction of separating the N pole of the rotor 2 by the coil 7 which is the drive coil as described above, and the third stator magnetic pole portion 5 is Since the excitation is performed in the direction of separating the south pole, the coil 6 as the detection coil is arranged in the direction of drawing the magnetic flux generated by the rotor. As a result, the level of the induced voltage generated in the coil 6 increases, and the detection accuracy of the induced voltage can be improved. Similarly, at the timing E, the second stator magnetic pole portion 4 is excited in the direction to separate the south pole of the rotor 2 by the coil 7 which is the drive coil as described above, and the third stator magnetic pole portion 5 is Since excitation is performed in a direction in which the N pole of the rotor 2 is separated, the coil 6 serving as a detection coil is disposed in a direction in which the magnetic flux generated by the rotor 2 is drawn. As a result, the level of the induced voltage generated in the coil 6 increases, and the detection accuracy of the induced voltage can be improved.

    The period of the second drive pulse at timing C and the inverted second drive pulse at timing F is preferably about 1 mS, and the chopper period is preferably about 200 μS to 250 μS. The reason why the second drive pulse and the inverted second drive pulse are chopper driven is that the drive energy is made smaller than that of the first drive pulse and the inverted first drive pulse, and the excessive braking effect on the rotor 2 is eliminated. This is to make the rotation operation 2 smooth. Further, the duty of the chopper waveform may be varied in order to adjust the drive energy of the second drive pulse and the inverted second drive pulse. Further, the second drive pulse and the inverted second drive pulse are not limited to chopper drive but may be full drive pulses, and the drive voltage and drive current may be adjusted to adjust the drive energy. .

Next, the rotation operation of the rotor 2 of the reversible stepping motor 1 in the reverse direction will be described with reference to FIG. For easy understanding, each operation will be described in six stages from timing A to timing F as in FIG. Moreover, a part of the description overlapping with FIG. 3 describing the rotation operation in the normal rotation direction is partially omitted. In FIG. 4, the timing A is a non-excitation state, no drive pulse is applied to the coils 6 and 7, the drive pulses O1 to O4 are both logic “1” (VDD), and the first stator magnetic pole portion 3, the second stator magnetic pole part 4 and the third stator magnetic pole part 5 are not excited, and the rotor 2 is stopped in the initial state with the N pole on the top and the S pole on the bottom.

    Next, timing B is the timing at which the first drive pulse is output to the coil 6, and the control circuit 11 sets the drive control signals P3 and P4 to logic "0", so the drive pulse O2 becomes logic "1". Further, since the control circuit 11 sets the drive control signals P1 and P2 to logic “1”, the drive pulse O1 is set to logic “0” (VSS), and a drive current flows from the coil terminal 6b of the coil 6 to the coil terminal 6a. . Thus, the coil 6 is a drive coil, the first stator magnetic pole portion 3 is excited to the N pole, the second stator magnetic pole portion 4 and the third stator magnetic pole portion 5 are excited to the S pole, and the rotor 2 is moved to the right ( Rotation is started at 90 degrees or more. Here, the first stator magnetic pole portion 3 is excited in a direction to separate the N pole of the rotor 2 (that is, excited to the N pole), and the third stator magnetic pole portion 5 is excited in a direction to separate the S pole of the rotor 2. (In other words, excitation to the S pole).

    At timing B, the control circuit 11 sets the drive control signal P7 to logic “1”, the drive control signal P8 to logic “0”, and turns off both the P-Tr 15a and N-Tr 15b of the inverter 15 to drive pulses. Let O4 be in a high resistance state. Similarly, the control circuit 11 sets the drive control signal P5 to logic “1”, the drive control signal P6 to logic “0”, turns off both the P-Tr 14a and N-Tr 14b of the inverter 14 and sets the drive pulse O3 to the high resistance state. To do. Here, since the AND circuit 24 inputs the drive control signal P5 and the inverted output of the drive control signal P6, the bias control signal P16, which is the output of the AND circuit 24, becomes logic "1", turns on the analog switch 27, and bias The bias voltage P17, which is the output of the circuit 26, is supplied to the drive pulse O3 in the high resistance state, so that the drive pulse O3 has the same potential as the bias voltage P17. That is, at the timing B, the drive pulse O3 is set to a voltage of about ½ VDD equal to the potential of the bias voltage P17, and the drive pulse O4 is set to a high resistance state.

    Here, since the drive pulses O3 and O4 are connected to the coil terminals 7a and 7b of the coil 7 as described above, the coil terminal 7b is in a high resistance state, the coil 7a is about 1/2 VDD, and the coil 7 is The detection coil detects the induced voltage. That is, when the rotor 2 starts to rotate by the coil 6 that is a drive coil, a change in magnetic flux generated by the rotation of the rotor 2 is transmitted to the coil 7 via the second stator magnetic pole portion 4 and the third stator magnetic pole portion 5. An induced voltage generated by the change of magnetic flux appears between the coil terminal 7a and the coil terminal 7b of the coil 7. Here, as described above, the drive pulse O3 connected to the coil terminal 7a has the same potential as the bias voltage P17 (that is, about ½ VDD), so it is connected to the coil terminal 7b which is the other terminal. In the drive pulse O4, an induced voltage is generated with reference to the potential of the drive pulse O3 (that is, the bias voltage P17). That is, the induced voltage is uniformly generated in the plus direction or the minus direction depending on the direction of change in magnetic flux around the potential of the bias voltage P17, so that an induced voltage with a wide dynamic range can be obtained.

Here, the voltage detection circuit 17 receives the drive pulse O4, detects the induced voltage, and outputs the detection signal P10 when the induced voltage reaches a predetermined voltage. The AND circuit 19 receives the detection signal P10 and the mask signal P11, performs a logical AND, and outputs a dynamic control signal P13. When the dynamic control signal P13 is input, the control circuit 11 immediately ends the first drive pulse at the timing B. The predetermined voltage detected by the voltage detection circuit 17 is preferably a voltage substantially equal to the bias voltage P17, and the rotor 2 is about 90 degrees from the initial non-excitation state in the vicinity of the induced voltage reaching the bias voltage P17. The position is rotated. Here, since the end of the first drive pulse is slightly delayed from when the induced voltage reaches the bias voltage P17, the rotor 2
4 reaches 90 ° + α from the initial state, and the rotational position of the rotor 2 at the timing B shown in FIG. 4 indicates the rotational position at the end of the timing B.

    Here, for example, when the load on the motor is light, the rotor 2 rotates quickly, so that the time from the start of timing B, which is the first drive pulse, until the induced voltage reaches the bias voltage P17 is shortened. The drive time of the first drive pulse is adjusted to be short. Further, when the load on the motor is heavy, the rotor 2 rotates slowly, so that the time until the induced voltage reaches the bias voltage P17 after the start of the timing B as the first drive pulse becomes long. As a result, the first The drive time of the drive pulse is adjusted to be long. That is, the pulse width of the first drive pulse is dynamically controlled by the control circuit 11 according to the rotation angle of the rotor 2 where the induced voltage appears. The pulse width of the first drive pulse is often controlled in the range of 2 mS to 4 mS in the normal state.

    Next, the timing C is a timing at which the second drive pulse is output immediately after the end of the first drive pulse, and the control circuit 11 outputs the drive control signals P1, P2 and the drive control signals P7, P8 in a short time. 1 "and logic" 0 "are repeated, and the drive pulses O1 and O4 are chopper driven as shown. Further, the control circuit 11 outputs the drive control signals P3, P4, P5, and P6 as logic “0”, and sets the drive pulses O2 and O3 to logic “1”. Thereby, a chopper driving current flows from the coil terminal 6b of the coil 6 toward the coil terminal 6a, and similarly, a chopper driving current flows from the coil terminal 7a of the coil 7 toward the coil terminal 7b.

    As a result, the two coils 6 and 7 both function as drive coils, the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 are excited to the N pole, and the third stator magnetic pole portion 5 is excited to the S pole. The Thereby, the S pole of the rotor 2 is attracted by the N pole of the second stator magnetic pole portion 4, and the N pole of the rotor 2 is separated by the N pole of the second stator magnetic pole portion 4 and the third stator magnetic pole portion 5 Since the rotor 2 is attracted by the S pole, the rotor 2 continues to rotate further in the right direction (reverse rotation) and rotates one step (ie, 180 degrees) from the initial state of non-excitation at timing A. When the rotor 2 rotates by one step, the S pole of the rotor 2 is attracted from both by the N poles of the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 to be braked, and the N pole of the rotor 2 is The brake is applied by being attracted to the S pole of the third stator magnetic pole portion 5, and the rotor 2 stops and stabilizes after one step rotation.

    Next, the period of the timing D is a non-excitation period again, the drive pulses O1 to O4 are both set to logic “1”, the drive current does not flow through the coils 6 and 7, and the rotor 2 is kept stopped. The

    Next, the operation of rotating the rotor 2 one step further from the position of the timing D in the right direction (reverse rotation) will be described. Timing E is the timing at which the inverted first drive pulse is output to the coil 6, and the control circuit 11 sets the drive control signals P3 and P4 to logic “1”, so that the drive pulse O2 becomes logic “0”. Since the control circuit 11 sets the drive control signals P1 and P2 to logic “0”, the drive pulse O1 is set to logic “1”, and a drive current flows from the coil terminal 6a of the coil 6 to the coil terminal 6b. As a result, the coil 6 is a drive coil, the first stator magnetic pole portion 3 is excited to the S pole, the second stator magnetic pole portion 4 and the third stator magnetic pole portion 5 are excited to the N pole, and the rotor 2 is moved rightward again. Rotation is started at (reverse rotation), and it is rotated 90 degrees or more from the position of the timing D. Here, the first stator magnetic pole portion 3 is excited in a direction to separate the south pole of the rotor 2 (that is, excited to the south pole), and the third stator magnetic pole portion 5 is excited in a direction to separate the north pole of the rotor 2. (In other words, excitation to the N pole).

At timing E, the control circuit 11 sets the drive control signal P7 to logic “1”, the drive control signal P8 to logic “0”, and turns off both the P-Tr 15a and N-Tr 15b of the inverter 15 to drive pulses. Let O4 be in a high resistance state. Similarly, the control circuit 11 sets the drive control signal P5 to logic “1”, the drive control signal P6 to logic “0”, turns off both the P-Tr 14a and N-Tr 14b of the inverter 14 and sets the drive pulse O3 to the high resistance state. To do. Here, since the AND circuit 24 inputs the drive control signal P5 and the inverted output of the drive control signal P6, the bias control signal P16, which is the output of the AND circuit 24, becomes logic "1", turns on the analog switch 27, and bias The bias voltage P17, which is the output of the circuit 26, is supplied to the drive pulse O3 in the high resistance state, so that the drive pulse O3 has the same potential as the bias voltage P17. That is, at the timing E, the drive pulse O3 is set to a voltage of about ½ VDD equal to the potential of the bias voltage P17, and the drive pulse O4 is set to a high resistance state.

    Here, since the drive pulses O3 and O4 are connected to the coil terminals 7a and 7b of the coil 7 as described above, the coil terminal 7b is in a high resistance state, the coil 7a is about 1/2 VDD, and the coil 7 is The detection coil detects the induced voltage. That is, when the rotor 2 starts to rotate by the coil 6 that is a drive coil, a change in magnetic flux generated by the rotation of the rotor 2 is transmitted to the coil 7 via the second stator magnetic pole portion 4 and the third stator magnetic pole portion 5. An induced voltage generated by the change of magnetic flux appears between the coil terminal 7a and the coil terminal 7b of the coil 7. Here, as described above, the drive pulse O3 connected to the coil terminal 7a has the same potential as the bias voltage P17 (that is, about ½ VDD), so it is connected to the coil terminal 7b which is the other terminal. In the drive pulse O4, an induced voltage is generated with reference to the potential of the drive pulse O3 (that is, the bias voltage P17). That is, the induced voltage is uniformly generated in the plus direction or the minus direction depending on the direction of change in magnetic flux around the potential of the bias voltage P17, so that an induced voltage with a wide dynamic range can be obtained. At the timing B, the magnetic pole of the rotor 2 causing the magnetic flux change is the N pole. However, the magnetic pole of the rotor 2 causing the magnetic flux change at the timing E is the S pole. Thus, the polarity of the induced voltage is reversed, and the induced voltage is generated on the minus side with respect to the bias voltage P17.

    Here, the voltage detection circuit 17 receives the drive pulse O4, detects the induced voltage, and outputs the detection signal P10 when the induced voltage reaches a predetermined voltage. The AND circuit 19 receives the detection signal P10 and the mask signal P11, performs a logical AND, and outputs a dynamic control signal P13. When receiving the dynamic control signal P13, the control circuit 11 immediately ends the inverted first drive pulse that is the timing E. The predetermined voltage detected by the voltage detection circuit 17 is preferably a voltage substantially equal to the bias voltage P17 as in the timing B, and the rotor 2 is moved from the non-excited state at the timing D in the vicinity of the induced voltage reaching the bias voltage P17. The position is rotated about 90 degrees. Here, since the end of the inverted first drive pulse is slightly delayed from the time when the induced voltage reaches the bias voltage P17, the rotation of the rotor 2 reaches 90 ° + α from the position of the timing D, and the timing shown in FIG. The rotational position of the rotor 2 at E indicates the rotational position at the end of the timing E.

Here, for example, when the load on the motor is light, the rotor 2 rotates quickly, so that the time from the start of the timing E, which is the inverted first drive pulse, until the induced voltage reaches the bias voltage P17 is shortened. The drive time of the inverted first drive pulse is adjusted to be short. Further, when the motor load is heavy, the rotor 2 rotates slowly, so that the time until the induced voltage reaches the bias voltage P17 after the start of the timing E, which is the reverse first drive pulse, becomes long. The drive time of the first drive pulse is adjusted to be long. In other words, the pulse width of the inverted first drive pulse is dynamically controlled by the control circuit 11 according to the rotation angle of the rotor 2 where the induced voltage appears. Note that the pulse width of the inverted first drive pulse is controlled in the range of 2 mS to 4 mS in the normal state as in the case of the above-described first drive pulse. However, in FIG. The pulse width of the pulse is shorter than the first drive pulse at timing B, and indicates that the first drive pulse and the inverted first drive pulse are dynamically controlled by a load variation of the motor.

    Next, timing F is a timing at which the inverted second drive pulse is output immediately after the end of the inverted first drive pulse, and the control circuit 11 sends the drive control signals P3 and P4 and the drive control signals P5 and P6 in a short time. The logic “1” and the logic “0” are repeated, and the drive pulses O2 and O3 are chopper driven as shown in the figure. Further, the control circuit 11 outputs the drive control signals P1, P2, P7, and P8 as logic “0”, and sets the drive pulses O1 and O4 to logic “1”. Thereby, a chopper drive current flows from the coil terminal 6a of the coil 6 toward the coil terminal 6b, and similarly, a chopper drive current flows from the coil terminal 7b of the coil 7 toward the coil terminal 7a.

    As a result, the two coils 6 and 7 both function as drive coils, the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 are excited to the S pole, and the third stator magnetic pole portion 5 is excited to the N pole. The Thus, the N pole of the rotor 2 is attracted by the S pole of the second stator magnetic pole portion 4, and the S pole of the rotor 2 is separated by the S pole of the second stator magnetic pole portion 4 and the third stator magnetic pole portion 5 Since it is attracted by the N pole, the rotor 2 continues to rotate further in the right direction (reverse rotation), and rotates one step (ie, 180 degrees) from the non-excited state at timing D. When the rotor 2 rotates by one step, the N pole of the rotor 2 is attracted from both by the S poles of the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 to be braked, and the S pole of the rotor 2 is The brake is applied by being attracted to the N pole of the third stator magnetic pole portion 5, and the rotor 2 stops and stabilizes after one step rotation. As described above, by repeating the timing A to the timing F, the rotor 2 rotates rightward (reversely) by two steps (that is, 360 degrees).

    At timing B, as described above, the first stator magnetic pole portion 3 is excited in the direction of separating the north pole of the rotor 2 by the coil 6 that is a drive coil, and the third stator magnetic pole portion 5 is Since the excitation is performed in the direction of separating the south pole, the coil 7 as the detection coil is arranged in the direction of drawing the magnetic flux generated by the rotor. As a result, the level of the induced voltage generated in the coil 7 increases, and the detection accuracy of the induced voltage can be improved. Similarly, at the timing E, as described above, the first stator magnetic pole portion 3 is excited in the direction of separating the S pole of the rotor 2 by the coil 6 that is the drive coil, and the third stator magnetic pole portion 5 is Since excitation is performed in the direction in which the N pole of the rotor 2 is separated, the coil 7 serving as a detection coil is disposed in a direction in which the magnetic flux generated by the rotor is drawn. As a result, the level of the induced voltage generated in the coil 7 increases, and the detection accuracy of the induced voltage can be improved.

    The period of the second drive pulse at timing C and the inverted second drive pulse at timing F is preferably about 1 mS, and the chopper period is preferably about 200 μS to 250 μS. The reason why the second drive pulse and the inverted second drive pulse are chopper-driven is the same as that described in the normal rotation operation of FIG.

Next, the induced voltage generated in the detection coil of the reversible stepping motor according to the first embodiment of the present invention and the operation of the voltage detection means will be described with reference to FIG. As a premise for explanation, explanation will be made based on the induced voltage generated when the rotor 2 of the reversible stepping motor is rotating forward. Here, as described above, the induced voltage is generated in the drive pulse O1 in the high resistance state in the period of the first drive pulse in the forward rotation operation of the rotor 2. The voltage detection circuit 16 as voltage detection means inputs the drive pulse O1 with the period of the first drive pulse as an induced voltage detection period, and determines whether the induced voltage reaches a bias voltage P15 as a predetermined voltage. When the induced voltage reaches the bias voltage P15 (that is, when the induced voltage is equal to or lower than the bias voltage P15 here), the detection signal P9 is output. The induced voltage may generate electrical noise as shown in FIG. 5 from the outside, and the detection signals P9a and P9b are the results of detecting the noise generated in the induced voltage, and the detection signal P9c. Is a correct detection signal for detecting that the induced voltage is equal to or lower than the bias voltage P15.

  Here, when the detection signals P9a and P9b detected by noise are input to the control circuit 11 as they are, the control circuit 11 erroneously recognizes that the induced voltage has reached a predetermined voltage by the detection signal P9a or the detection signal P9b. Thus, there is a risk that the first drive pulse is ended and, as a result, the rotation of the rotor 2 is stopped. In order to minimize the influence of noise generated on such an induced voltage, in this embodiment, a mask circuit by an AND circuit 18 is provided after the voltage detection circuit 16, and a predetermined circuit is detected during the induced voltage detection period of the voltage detection circuit 16. Measures are taken to provide a mask period.

    That is, as shown in FIG. 5, the mask signal P11 is a signal that becomes logic “0” in synchronization with the start of the first drive pulse period and returns to logic “1” in the middle of the first drive pulse period. Since the detection signal P9 is logically ANDed with the mask signal P11 by the AND circuit 18, the detection signal P9 is generated by noise of the induced voltage during the logic “0” period, that is, the mask period. However, the dynamic control signal P12 due to noise is not masked and output to the dynamic control signal P12 which is the output of the AND circuit 18, and is generated during the period when the mask signal P11 is set to logic "1". The detected signal P9c is input to the control circuit 11 as the dynamic control signal P12c. Thus, in the present invention, since the mask period can be provided during the induced voltage detection period of the voltage detection circuit 16, malfunction due to electrical noise generated in the induced voltage within the mask period is prevented, and the drive pulse The reliability of dynamic control can be improved.

    As described above, the voltage detection circuit 16 has a built-in hysteresis circuit 16a and provides hysteresis characteristics for detecting the induced voltage. That is, the hysteresis circuit 16a functions as a voltage hysteresis means, and outputs a detection signal P9 when the induced voltage is further lowered from the bias voltage P15 by the hysteresis voltage as shown in FIG. Thereby, for example, when a noise component having a small amplitude is superimposed on the induced voltage, it is possible to prevent malfunction of the detection signal P9 due to noise and improve the reliability of dynamic control of the drive pulse. The hysteresis voltage is preferably in the range of 1% to 10% with respect to the power supply voltage. The hysteresis circuit 16a may function as time hysteresis means for outputting the detection signal P9 after a lapse of a fixed time after the induced voltage reaches the bias voltage P15.

    That is, a function of outputting the detection signal P9 when the induced voltage continues below the bias voltage P15 within a predetermined time after the induced voltage becomes equal to or less than the bias voltage P15 may be used. When the dynamic control signal P12 is output, the control circuit 11 immediately ends the period of the first drive pulse and shifts to the period of the second drive pulse. The description in FIG. 5 is based on the assumption that the rotor 2 is rotating forward. However, in the reverse rotation operation, other basics are provided except that an induced voltage is generated in the drive pulse O4. Since the operation is the same, the description is omitted.

Next, another form of the first drive pulse of the reversible stepping motor according to the first embodiment of the present invention will be described with reference to FIG. As a premise for explanation, the form of the first drive pulse when the rotor 2 of the reversible stepping motor is rotating forward will be described. In FIG. 6, an induced voltage is generated in the drive pulse O1, as shown, during the period of the first drive pulse. The mask signal P11 is a signal that becomes logic “0” in synchronization with the start of the period of the first drive pulse and returns to logic “1” after a predetermined time. The period when the mask signal P11 is logic “0” is the period for masking detection of the induced voltage as described above. The drive pulse O4 has a chopper drive period in which logic “1” and logic “0” are repeated in a constant cycle in synchronization with the mask period by the mask signal P11, and the logic “1” coincides with the end of the mask period of the mask signal P11. 0 ”is a full drive pulse period that continues.

    That is, during the chopper driving period of the first driving pulse, a chopper driving current flows from the coil terminal 7a of the coil 7 to which the driving pulses O3 and O4 are connected to the coil terminal 7b, and the first driving pulse. Similarly, during the full drive pulse period, a full drive current flows from the coil terminal 7a of the coil 7 to which the drive pulses O3 and O4 are connected toward the coil terminal 7b. Here, during the chopper driving period, a noise component as shown in the figure may be superimposed on the induced voltage generated in the driving pulse O1 due to the influence of the chopper driving current flowing in the coil 7. Since the chopper drive period is also a mask period by the mask signal P11 as described above, the noise component is masked by the mask signal P11, and the dynamic control of the drive pulse does not malfunction and the reliability is maintained.

    In addition, the reason why a part of the first drive pulse is chopper-driven is that a part of the drive current flowing in the drive coil is used as a chopper drive current, thereby realizing low power consumption for motor drive. In addition, the reason why the first drive pulse is set to the full drive pulse period in the period other than the mask period is that the drive current in the full drive pulse is close to the direct current, so that it is difficult to generate a noise component, and the induced voltage has noise. This is because the voltage detection circuit 16 can be prevented from malfunctioning because it is not superimposed. The description in FIG. 6 is based on the assumption that the rotor 2 is rotating forward. However, in the reverse rotation operation, an induced voltage is generated in the drive pulse O4 and the drive pulse O1 is chopper driven. Except for this, the other basic operations are the same, and a description thereof will be omitted.

    Next, the high-speed driving operation of the reversible stepping motor according to the first embodiment of the present invention will be described with reference to FIG. The high-speed driving operation refers to a driving operation in which the driving cycle of one step is very short (for example, 10 mS or less), and as a premise for explanation, the high-speed driving of the fixed driving cycle method in which the driving cycle of one step is fixed. It is an operation, and the rotation direction of the rotor 2 is a normal rotation operation. In FIG. 7, drive pulses O1 to O4 operate in accordance with the drive operation described above with reference to FIG. 3, and a first drive pulse period by a full drive pulse, followed by a second drive pulse period by chopper drive. Then, the operation continues with the inverted first drive pulse period by the full drive pulse and then the inverted second drive pulse period by the chopper drive.

    Here, as described above, the driving cycle of one step is fixed, and the driving cycle is assumed to be 5.5 mS as an example. Here, as shown in the figure, since the induced voltage generated in the drive pulse O1 reaches the bias voltage P15 when the period of the first drive pulse has passed 4 mS, the first drive pulse period ends immediately, and the second drive pulse period Is started. If the second drive pulse period is fixed at 1 mS, the total period of the first drive pulse and the second drive pulse is 4 mS + 1 mS = 5 mS. Here, since the driving period is 5.5 mS, the driving period− (first driving pulse period + second driving pulse period) = 0.5 mS, and, as shown in the drawing, 0.5 mS is not present after the end of the second driving pulse. There is an excitation period, and the fixed driving cycle is maintained. Next, in the first inversion pulse period, the motor load becomes heavy for some reason and the rotation of the rotor 2 is slow, so that the induced voltage does not reach the bias voltage P15 even if the inversion pulse period has passed 4.5 mS. ing.

Here, as described above, since the driving cycle of one step is determined to be 5.5 mS, if the second pulse width is fixed at 1 mS, the maximum value of the inverted first driving pulse width is 5.5 mS. −1 mS = 4.5 mS, and the inverted first drive pulse width is ensured up to the maximum value of 4.5 mS. That is, when the drive cycle of the drive pulse is a fixed cycle, the first drive pulse (or inverted first drive pulse) is secured up to the difference between the width of the drive cycle and the second drive pulse (or inverted second drive pulse). Thus, the pulse width of the first drive pulse (or the inverted first drive pulse) is not further extended. However, the high-speed driving is not limited to the fixed driving cycle method, and the first driving pulse (or the inverted first driving pulse) until the induced voltage generated in the first driving pulse (or the inverted first driving pulse) reaches the bias voltage P15. A variable drive cycle method in which the pulse width of the drive pulse) is extended and the drive cycle is variable may be used.

    In addition, the variable drive cycle method with a time limit that extends the pulse width of the first drive pulse (or the inverted first drive pulse) not until the induced voltage reaches the bias voltage but for a predetermined time as a limit. good. Here, to summarize each driving method in the high-speed driving, the fixed driving cycle method shown in FIG. 7 secures the pulse width of the first driving pulse up to the maximum pulse width determined by the driving cycle of the driving pulse. A reversible stepping motor with high reliability against disturbances such as fluctuations can be provided. Furthermore, there is a great effect that the high-speed driving step feed can always be sent constantly. However, when a relatively large fluctuation occurs in the load fluctuation of the motor or the power supply voltage, the first driving pulse is forcibly terminated. Therefore, there is a possibility that there is no margin in drive torque.

    In addition, the variable drive cycle method can change the drive cycle in response to motor load fluctuations and power supply voltage fluctuations, and can secure the necessary drive torque, thereby realizing highly reliable motor drive. In the variable drive cycle method, when the power supply voltage is sufficiently high, the drive torque is large, so the first drive pulse width is shortened, and the drive cycle is shortened accordingly. In addition, when the power supply voltage is low, the driving torque is small, so the first driving pulse width is increased to ensure the driving torque, and the driving cycle is increased accordingly. Therefore, in the variable drive cycle method, the drive cycle changes in accordance with fluctuations in the motor load, power supply voltage, etc., so constant constant high-speed driving cannot be performed.

    The variable drive cycle method with time limit is an intermediate method between the fixed drive cycle method and the variable drive cycle method, and it can secure a certain amount of drive torque required for fluctuations in motor load and power supply voltage. The variable amount can be suppressed by limiting the change of the driving cycle with respect to the motor load fluctuation or the power supply voltage fluctuation. As described above, each driving method has a characteristic effect. Therefore, each method may be selected in consideration of the specifications of the reversible stepping motor. Note that FIG. 7 has been described on the assumption that the rotor 2 rotates in the forward direction. However, the same applies to the reverse operation of the rotor 2, and the description thereof is omitted. As described above, according to the first embodiment of the present invention, the necessary driving torque can be adjusted by dynamically controlling the driving pulse in response to disturbances such as motor load fluctuation and power supply voltage fluctuation, thereby realizing stable motor driving. A reversible stepping motor can be provided. In addition, since the motor drive can be reduced in power consumption and can sufficiently cope with high-speed drive, a highly reliable reversible stepping motor suitable for various applications can be realized.

    Next, a normal rotation driving method of the reversible stepping motor according to the second embodiment of the present invention will be described with reference to FIG. The driving method of the second embodiment is characterized in that the driving pulse is composed of a first driving pulse, a second driving pulse, and a third driving pulse. For easy understanding, each operation will be described in 8 stages from timing G to timing N. Further, the reversible stepping motor and the drive circuit of the second embodiment are the same as those of the first embodiment, so that the description thereof will be omitted. Refer to FIG. 1 for the configuration of the reversible stepping motor, and refer to FIG. . In FIG. 8, the timing G is a non-excited state, which is the same as the timing A described in FIG. Next, timing H is a timing at which the first drive pulse is output to the coil 7. A drive current flows through the coil 7 and the rotor 2 starts to rotate leftward (forward rotation) as shown in the figure. The form of the drive pulse and the rotation operation of the rotor 2 are the same as the timing B described in FIG.

Next, the timing I is the timing at which the second drive pulse is output immediately after the end of the first drive pulse. The control circuit 11 outputs the drive control signals P1 to P8, respectively, and sets the drive pulses O1 and O3 to logic “ 0 "and drive pulses O2 and O4 are set to logic" 1 ". Thereby, a drive current flows from the coil terminal 6b of the coil 6 toward the coil terminal 6a, and a drive current flows from the coil terminal 7b of the coil 7 toward the coil terminal 7a. As a result, the two coils 6 and 7 both function as drive coils, the first stator magnetic pole portion 3 is excited to the N pole, the second stator magnetic pole portion 4 is excited to the S pole, and the third stator magnetic pole portion 5 is excited. Becomes non-excited because the S and N poles cancel each other. As a result, the N pole of the rotor 2 is separated by the N pole of the first stator magnetic pole portion 3, and the S pole of the rotor 2 is separated by the S pole of the second stator magnetic pole portion 4. Continue rotating at (forward). Note that the pulse width of the second drive pulse at the timing I is fixed, and is preferably about 1 mS.

    Next, timing J is the timing at which the third drive pulse is output immediately after the end of the second drive pulse, and the control circuit 11 outputs the drive control signals P1 to P8, respectively, and sets the drive pulses O1 and O4 to logic “ 0 "and drive pulses O2 and O3 are set to logic" 1 ". Thereby, a drive current flows continuously from the coil terminal 6b of the coil 6 toward the coil terminal 6a, and a drive current flows from the coil terminal 7a of the coil 7 toward the coil terminal 7b. As a result, the two coils 6 and 7 both function as drive coils, the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 are excited to the N pole, and the third stator magnetic pole portion 5 is excited to the S pole. The Thereby, the S pole of the rotor 2 is attracted from both by the N poles of the first stator magnetic pole part 3 and the second stator magnetic pole part 4 to be braked, and the N pole of the rotor 2 is applied to the third stator magnetic pole part 5. The brake is applied by being attracted to the S pole, and the rotor 2 stops and stabilizes after one step (ie, 180 degrees). Note that the pulse width of the third drive pulse at the timing J is fixed, and is preferably about 1 mS.

    Next, the period of the timing K is again a non-excitation period, the drive pulses O1 to O4 are both set to logic “1”, the drive current does not flow through the coils 6 and 7, and the rotor 2 is kept stopped. The Next, the timing L is the timing at which the inverted first drive pulse is output to the coil 7, and the inverted drive current flows through the coil 7 so that the rotor 2 rotates again in the left direction (forward rotation) as shown in the figure. Although it starts, the form of the drive pulse and the rotation operation of the rotor 2 are the same as the timing E described in FIG.

    Next, timing M is a timing at which the inverted second drive pulse is output immediately after the end of the inverted first drive pulse, and the control circuit 11 outputs the drive control signals P1 to P8 respectively to generate the drive pulses O2 and O4. The logic is “0”, and the drive pulses O1 and O3 are logic “1”. Thereby, a drive current flows from the coil terminal 6a of the coil 6 toward the coil terminal 6b, and a drive current flows from the coil terminal 7a of the coil 7 toward the coil terminal 7b. As a result, the two coils 6 and 7 both function as drive coils, the first stator magnetic pole portion 3 is excited to the S pole, the second stator magnetic pole portion 4 is excited to the N pole, and the third stator magnetic pole portion 5 is excited. Becomes non-excited because the S and N poles cancel each other. As a result, the south pole of the rotor 2 is separated by the south pole of the first stator magnetic pole portion 3, and the north pole of the rotor 2 is separated by the north pole of the second stator magnetic pole portion 4. Continue rotating at (forward). Note that the pulse width of the inverted second drive pulse at the timing M is fixed, and is preferably about 1 mS.

Next, the timing N is a timing at which the inverted third drive pulse is output immediately after the end of the inverted second drive pulse, and the control circuit 11 outputs the drive control signals P1 to P8 to output the drive pulses O2 and O3, respectively. The logic is “0”, and the drive pulses O1 and O4 are logic “1”. Thereby, a drive current flows continuously from the coil terminal 6a of the coil 6 toward the coil terminal 6b, and a drive current flows from the coil terminal 7b of the coil 7 toward the coil terminal 7a. As a result, the two coils 6 and 7 both function as drive coils, the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 are excited to the S pole, and the third stator magnetic pole portion 5 is excited to the N pole. The Thereby, the N pole of the rotor 2 is attracted from both by the S pole of the first stator magnetic pole part 3 and the second stator magnetic pole part 4 to be braked, and the S pole of the rotor 2 is applied to the third stator magnetic pole part 5 The brake is applied by being attracted to the N pole, and the rotor 2 stops and stabilizes after one step (ie, 180 degrees). Note that the pulse width of the inverted third drive pulse at the timing N is fixed, and is preferably about 1 mS.

    Next, the reverse drive system of the reversible stepping motor according to the second embodiment of the present invention will be described with reference to FIG. Note that the reverse drive method is an operation in which the drive pulse O1 and the drive pulse O4 and the drive pulse O2 and the drive pulse O3 are switched with respect to the forward drive method in FIG. To do. In FIG. 9, the timing G is a non-excited state, which is the same as the timing A described in FIG. Next, the timing H is a timing at which the first drive pulse is output to the coil 6. A drive current flows through the coil 6 and the rotor 2 starts to rotate in the right direction (reverse rotation) as shown in FIG. Since the pulse form and the rotation operation of the rotor 2 are the same as the timing B described in FIG. 4 of the first embodiment, a detailed description thereof is omitted.

    Next, the timing I is a timing at which the second drive pulse is output immediately after the end of the first drive pulse. The control circuit 11 outputs the drive control signals P1 to P8, respectively, and sets the drive pulses O2 and O4 to logic “ 0 "and the drive pulses O1 and O3 are set to logic" 1 ". Thereby, a drive current flows from the coil terminal 6a of the coil 6 toward the coil terminal 6b, and a drive current flows from the coil terminal 7a of the coil 7 toward the coil terminal 7b. As a result, the two coils 6 and 7 both function as drive coils, the first stator magnetic pole portion 3 is excited to the S pole, the second stator magnetic pole portion 4 is excited to the N pole, and the third stator magnetic pole portion 5 is excited. Becomes non-excited because the S and N poles cancel each other. As a result, the S pole of the rotor 2 is separated by the S pole of the first stator magnetic pole portion 3, and the N pole of the rotor 2 is separated by the N pole of the second stator magnetic pole portion 4. Continue to rotate (reverse).

    Next, timing J is the timing at which the third drive pulse is output immediately after the end of the second drive pulse, and the control circuit 11 outputs the drive control signals P1 to P8, respectively, and sets the drive pulses O1 and O4 to logic “ 0 "and drive pulses O2 and O3 are set to logic" 1 ". Thereby, a drive current flows from the coil terminal 6b of the coil 6 toward the coil terminal 6a, and a drive current continuously flows from the coil terminal 7a of the coil 7 toward the coil terminal 7b. As a result, the two coils 6 and 7 both function as drive coils, the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 are excited to the N pole, and the third stator magnetic pole portion 5 is excited to the S pole. The Thereby, the S pole of the rotor 2 is attracted from both by the N poles of the first stator magnetic pole part 3 and the second stator magnetic pole part 4 to be braked, and the N pole of the rotor 2 is applied to the third stator magnetic pole part 5. The brake is applied by being attracted to the S pole, and the rotor 2 stops and stabilizes after one step (ie, 180 degrees).

    Next, the period of the timing K is again a non-excitation period, the drive pulses O1 to O4 are both set to logic “1”, the drive current does not flow through the coils 6 and 7, and the rotor 2 is kept stopped. The Next, the timing L is the timing at which the inverted first drive pulse is output to the coil 6, and the inverted drive current flows to the coil 6 so that the rotor 2 starts to rotate again in the right direction (reverse) as shown in the figure. However, since the form of the drive pulse and the rotation operation of the rotor 2 are the same as the timing E described in FIG.

Next, the timing M is a timing at which the inverted second drive pulse is output immediately after the end of the inverted first drive pulse, and the control circuit 11 outputs the drive control signals P1 to P8 to output the drive pulses O1 and O3, respectively. The logic is “0”, and the drive pulses O2 and O4 are logic “1”. Thereby, a drive current flows from the coil terminal 6b of the coil 6 toward the coil terminal 6a, and a drive current flows from the coil terminal 7b of the coil 7 toward the coil terminal 7a. As a result, the two coils 6 and 7 both function as drive coils, the first stator magnetic pole portion 3 is excited to the N pole, the second stator magnetic pole portion 4 is excited to the S pole, and the third stator magnetic pole portion 5 is excited. Becomes non-excited because the S and N poles cancel each other. As a result, the N pole of the rotor 2 is separated by the N pole of the first stator magnetic pole portion 3, and the S pole of the rotor 2 is separated by the S pole of the second stator magnetic pole portion 4, so that the rotor 2 further moves in the right direction. Continue to rotate (reverse).

    Next, the timing N is a timing at which the inverted third drive pulse is output immediately after the end of the inverted second drive pulse, and the control circuit 11 outputs the drive control signals P1 to P8 to output the drive pulses O2 and O3, respectively. The logic is “0”, and the drive pulses O1 and O4 are logic “1”. Thereby, a drive current flows from the coil terminal 6a of the coil 6 toward the coil terminal 6b, and a drive current continuously flows from the coil terminal 7b of the coil 7 toward the coil terminal 7a. As a result, the two coils 6 and 7 both function as drive coils, the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 are excited to the S pole, and the third stator magnetic pole portion 5 is excited to the N pole. The Thereby, the N pole of the rotor 2 is attracted from both by the S pole of the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 to be braked, and the S pole of the rotor 2 is applied to the third stator magnetic pole portion 5. The brake is applied by being attracted to the N pole, and the rotor 2 stops and stabilizes after one step (ie, 180 degrees).

    As described above, in the driving method of the second embodiment, the second driving pulse (or the inverted second driving pulse) is output after the first driving pulse (or the inverted first driving pulse). Since the force separated by the first stator magnetic pole part 3 and the second stator magnetic pole part 4 works, the rotational torque of the rotor 2 further increases. Further, the third drive pulse (or the inverted third drive pulse) is output after the second drive pulse (or the inverted second drive pulse), so that the rotor 2 has the first stator magnetic pole part 3 and the second stator magnetic pole part. 4 and the third stator magnetic pole part 5 are attracted and braked, and the rotor 2 stops and stabilizes after one step (ie, 180 degrees). As described above, according to the driving method of the second embodiment, the rotational torque of the rotor 2 is increased by the second driving pulse (or the inverted second driving pulse), and the rotor is driven by the third driving pulse (or the inverted third driving pulse). Therefore, as compared with the driving method of the first embodiment, the driving torque is large, impact resistance is improved, and a reversible stepping motor with high reliability can be provided.

    The motor driving in the second embodiment has been described on the premise of the low speed driving that drives one step per second, for example, but the same driving is performed even if the driving cycle of one step is very short. I can do it. That is, the high-speed driving operation of the fixed driving cycle method in which the driving cycle of one step described in FIG. 7 of the first embodiment is fixed is the second driving pulse and the third driving pulse shown in FIG. 8 after the first driving pulse. By inserting, the high-speed driving of the second embodiment can be realized. Needless to say, in the high-speed driving, the variable drive cycle method and the variable drive cycle method with time limit described in the first embodiment can be similarly realized. The second drive pulse and the third drive pulse shown in FIGS. 8 and 9 are full drive pulses. However, the present invention is not limited to this, and the second drive pulse and / or the third drive pulse may be used. The driving pulse may be chopper driving.

    In the high-speed driving of the reversible stepping motor 1 according to the first and second embodiments, the first driving pulse and the second driving pulse are used to give sufficient rotational torque to the rotor 2 when the reversible stepping motor 1 is started. Alternatively, the first driving pulse, the second driving pulse, and the third driving pulse are used for driving, and the rotor 2 is inertial during continuous driving, so that driving is performed using only the first driving pulse in order to reduce driving power consumption. A driving method may be adopted. Similarly, in the high-speed driving of the reversible stepping motor 1 according to the first and second embodiments, only the first driving pulse is driven during continuous driving, and sufficient braking is applied to the rotor 2 when the rotor 2 is stopped. Alternatively, a driving method in which the first driving pulse and the second driving pulse, or the first driving pulse, the second driving pulse, and the third driving pulse are used may be adopted.

    Next, the structure of a reversible stepping motor as Embodiment 3 of the present invention will be described with reference to FIG. The reversible stepping motor according to the third embodiment is similar in basic structure to the reversible stepping motor according to the first embodiment, and therefore, the same components are denoted by the same reference numerals and redundant description is partially omitted. In FIG. 10, reference numeral 30 denotes a reversible stepping motor according to the third embodiment of the present invention. Reference numeral 2 denotes a rotor, which is composed of a cylindrical magnet in which N and S poles are magnetized in the radial direction. Reference numerals 3 and 4 denote a first stator magnetic pole part and a second stator magnetic pole part provided opposite to each other with the rotor 2 interposed therebetween. Reference numeral 5 denotes a third stator magnetic pole portion provided between the first and second stator magnetic pole portions and facing the rotor 2. 6 and 7 are two coils, the coil 6 is magnetically coupled to the first stator magnetic pole part 3 and the third stator magnetic pole part 5, and the coil 7 is connected to the second stator magnetic pole part 4 and the third stator magnetic pole part 5. Magnetically coupled.

    Reference numerals 31, 32, and 33 denote magnetic saturation portions formed in the separated gaps surrounding the rotor 2 of each stator magnetic pole portion, and the magnetic saturation portion 31 includes the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4. The magnetic saturation part 32 is provided in the separation gap between the first stator magnetic pole part 3 and the third stator magnetic pole part 5, and the magnetic saturation part 33 is provided between the second stator magnetic pole part 4 and the third stator magnetic pole part 4. It is provided in the separated gap of the stator magnetic pole part 5. Reference numeral 34 denotes a support plate made of a non-magnetic material, and the first, second, and third stator magnetic pole portions separated from each other by the magnetic saturation portions 31 to 33 are one of fixing means. Mechanically joined by some welding. Reference numerals 35a, 35b, and 35c denote welding locations for connecting the support plate 34 to the first, second, and third stator magnetic pole portions, and the first, second, and third portions are indicated by the welding locations 35a, 35b, and 35c. The third stator magnetic pole portions can be coupled to each other via the support plate 34 so that the mechanical strength can be maintained and the interval between the magnetic saturation portions can be kept constant.

    Here, for example, when a drive pulse is supplied to the coil 7 and a drive current flows from the coil terminal 7a to the coil terminal 7b as shown at timing H in FIG. 8, a magnetic flux is generated by the coil 7, and the second stator magnetic pole portion 4 is N The pole, the first stator magnetic pole part 3 and the third stator magnetic pole part 5 are excited to the S pole. At this time, the magnetic saturation part 31 provided in the gap between the first stator magnetic pole part 3 and the second stator magnetic pole part 4 is separated from the first stator magnetic pole part 3 and the second stator magnetic pole part 4 as described above. And is coupled by a support plate 34, which is a non-magnetic material, so that the magnetic resistance is extremely large, and the first stator magnetic pole portion 3 and the second stator magnetic pole portion 4 are in a magnetically separated state. . As a result, most of the magnetic flux generated by the coil 7 cannot pass through the magnetic saturation part 31, and strong magnetic poles are generated in the first stator magnetic pole part 3 and the second stator magnetic pole part 4.

    Similarly, when a drive pulse is supplied to the coil 6 and a drive current flows from the coil terminal 6a to the coil terminal 6b as shown in the timing N of FIG. 8, a magnetic flux is generated by the coil 6, and the first stator magnetic pole portion 3 is turned to the S pole The third stator magnetic pole portion 5 is excited to the N pole. Here, the magnetic saturation part 32 provided in the gap between the first stator magnetic pole part 3 and the third stator magnetic pole part 5 has an extremely large magnetic resistance like the magnetic saturation part 31 and the first stator magnetic pole part 3 and the third stator. The magnetic pole portion 5 is magnetically separated. As a result, most of the magnetic flux generated by the coil 6 cannot pass through the magnetic saturation part 32, and strong magnetic poles are generated in the first stator magnetic pole part 3 and the third stator magnetic pole part 5.

Further, when a drive pulse is supplied to the coil 7 and a drive current flows from the coil terminal 7a to the coil terminal 7b as shown in the timing J of FIG. 8, a magnetic flux is generated by the coil 7, and the second stator magnetic pole portion 4 has an N pole, The third stator magnetic pole part 5 is excited to the S pole. Here, the magnetic saturation part 33 provided in the gap between the second stator magnetic pole part 4 and the third stator magnetic pole part 5 has an extremely large magnetic resistance like the magnetic saturation part 32, and the second stator magnetic pole part 4 and the third stator magnetic pole part. The part 5 is magnetically separated. As a result, most of the magnetic flux generated by the coil 7 cannot pass through the magnetic saturation part 33, and strong magnetic poles are generated in the second stator magnetic pole part 4 and the third stator magnetic pole part 5.

    As described above, since the first, second, and third stator magnetic pole portions 3 to 5 are magnetically separated by the magnetic saturation portions 31 to 33, a strong magnetic pole is generated in each stator magnetic pole portion. A reversible stepping motor having enhanced drive torque for the rotor 2, sufficient power, and good drive efficiency can be provided. In addition, since the induced voltage generated in the coil 6 or the coil 7 serving as the detection coil reduces the leakage of magnetic flux between the first, second, and third stator magnetic pole portions by the magnetic saturation portions 31 to 33, It is possible to provide a reversible stepping motor in which the level of the induced voltage is increased, the S / N ratio is improved, the detection accuracy of the induced voltage is improved, and dynamic control with high reliability is realized. In addition, since the drive system of the reversible stepping motor 30 according to the third embodiment can be applied to the drive systems according to the first and second embodiments as described above, a detailed description of the drive system is omitted.

    The circuit block diagram presented in the embodiment of the present invention is not limited to this, and can be arbitrarily changed without departing from the gist of the present invention. In addition, the waveform of each drive pulse presented in the embodiment of the present invention is not limited to this, and the waveform form of each drive pulse may be arbitrarily changed as long as the same function is satisfied.

It is a schematic diagram which shows the structure of the reversible stepping motor of Example 1 of this invention. It is a circuit block diagram of the drive circuit which drives the reversible stepping motor of Example 1 of the present invention. It is explanatory drawing which shows the timing chart of the drive pulse which makes the reversible stepping motor of Example 1 of this invention perform normal rotation, and the rotational operation of a rotor. It is explanatory drawing which shows the timing chart of the drive pulse which reversely rotates the reversible stepping motor of Example 1 of this invention, and rotation operation of a rotor. It is a timing chart explaining operation | movement of the induced voltage and voltage detection circuit which generate | occur | produce in the detection coil of the reversible stepping motor of Example 1 of this invention. It is a timing chart explaining another form of the induced voltage and drive pulse which generate | occur | produce in the detection coil of the reversible stepping motor of Example 1 of this invention. It is a timing chart explaining the high-speed drive operation | movement of the reversible stepping motor of Example 1 of this invention. It is explanatory drawing which shows the timing chart of the drive pulse which makes the reversible stepping motor of Example 2 of this invention perform normal rotation, and the rotational operation of a rotor. It is explanatory drawing which shows the timing chart of the drive pulse which reversely rotates the reversible stepping motor of Example 2 of this invention, and the rotational operation of a rotor. It is a schematic diagram which shows the structure of the reversible stepping motor of Example 3 of this invention. It is a schematic diagram which shows the structure of the conventional double rotation step motor. It is an example of the drive circuit of the conventional double rotation step motor. It is explanatory drawing explaining the form of the drive pulse supplied to the conventional double rotation step motor, and rotation operation of the double rotation step motor driven by this drive pulse.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,30 Reversible stepping motor 2,101 Rotor 3 1st stator magnetic pole part 4 2nd stator magnetic pole part 5 3rd stator magnetic pole part 6, 7, 105, 106 Coil 6a, 6b, 7a, 7b Coil terminal 8a, 8b, 8c , 31, 32, 33 Magnetic saturation unit 11 Control circuit 12, 13, 14, 15, 21, 25, 121, 122, 123 Inverter 12a, 13a, 14a, 15a, 123a P-Tr
12b, 13b, 14b, 15b, 123b N-Tr
16, 17 Voltage detection circuit 16a, 17a Hysteresis circuit 18, 19, 20, 24 AND circuit 22, 26 Bias circuit 23, 27 Analog switch 34 Support plate 35a, 35b, 35c Welded part 102, 103 Main magnetic pole 104 Sub magnetic pole 107, 108, 109, 110 Winding terminal 120 Electronic circuit O1-O4 Drive pulse P1-P8 Drive control signal P9, P10 Detection signal P11 Mask signal P12, P13 Dynamic control signal P14, P16 Bias control signal P15, P17 Bias voltage

Claims (5)

A rotor magnetized in at least two poles in the radial direction;
First and second stator magnetic pole portions provided substantially opposite to each other via the rotor;
A third stator pole portion provided between the first and second stator pole portions and facing the rotor;
A first coil that is magnetically coupled to the first stator pole portion and the third stator pole portion;
A second coil magnetically coupled to the second stator pole part and the third stator pole part;
Driving means for outputting a driving pulse for driving the first coil and the second coil;
While the driving means is driving one of the first coil or the second coil,
The other of the first coil or the second coil is
A reversible stepping motor used as a detection coil for detecting an induced voltage generated according to the rotation of the rotor ,
The driving means includes
At least one coil terminal of the detection coil is in a high resistance state,
A predetermined voltage is applied to the other coil terminal of the high resistance state terminal.
Voltage detecting means for detecting the induced voltage at the terminal in the high resistance state;
The drive means is within an induced voltage detection period in the detection coil.
Providing a predetermined mask period for masking a detection signal from the voltage detection means;
A reversible stepping motor, wherein the driving pulse during the mask period is chopper driving . The driving pulse for driving the first coil or the second coil is :
A first drive pulse and a second drive pulse;
Or a first drive pulse, a second drive pulse and a third drive pulse, and
Wherein Ri formed by the inversion driving pulses obtained by inverting the driving current of the driving pulse,
The driving means includes
If the voltage detection means detects that the induced voltage generated by the detection coil has reached a predetermined voltage,
While stopping the first drive pulse for driving the first coil or the second coil to dynamically control the first drive pulse width,
After the output of the first drive pulse is finished,
The second drive pulse, or the second drive pulse and the third drive pulse are output immediately, and the first drive pulse during the mask period is set to chopper drive. The reversible stepping motor according to claim 1 , wherein: The driving means includes
Outside the mask period,
The reversible stepping motor according to claim 2, wherein the first drive pulse for driving the first coil or the second coil is a full drive pulse. The reversible according to any one of claims 1 to 3, wherein the predetermined voltage applied to the other terminal of the first coil or the second coil is approximately ½ of a power supply voltage. Stepping motor. The driving means includes
4. The reversible stepping motor according to claim 2 , wherein driving energy is reduced by chopper driving the second driving pulse and the third driving pulse. 5.

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