Step motor driver and lens-moving apparatus

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a drive device for driving a two-phase PM type step motor (stepping motor) and a lens moving device including a step motor driven by the device.

【0002】

[Conventional technology]

A lens barrel device in which a camera lens is moved in the optical axis direction by using a step motor driven by a pulse signal is known, for example, as proposed in Japanese Patent Application Laid-Open No. 6-250070. .. In the lens barrel, by controlling the drive frequency and the number of drive pulses (steps) of the step motor, the position of the lens in the optical axis direction can be controlled more accurately than when a DC motor or the like is used, which is more appropriate. You can shoot with a camera.

【0003】

In this conventional example, the lens is moved in the direction of the optical axis, but there is also a pickup that reads information recorded on an information recording disk such as a CD or DVD, in which the lens is moved in a direction perpendicular to the optical axis.

【0004】

Further, one of the techniques for controlling the fine position is a microstep drive method in which the energizing current to the coil is changed stepwise and the rotor of the motor is stopped at the position corresponding to the energizing current.

【0005】

[Problems to be Solved by the Invention]

However, when the rotor is stopped by microstep control, if the driving force for positioning at that position is small, it cannot be stopped at a desired position due to the influence of friction and the driving load, and a stop position error remains. In particular, the closer the position of the rotor is to the position where it is originally positioned by microstep control, the smaller the rotational driving force generated when trying to position it at that original position becomes smaller, and there is only a slight frictional force, which is the original position. Positioning becomes difficult.

【0006】

On the other hand, if the rotor is simply rotated, it is easy to rotate the rotor with a certain delay with respect to the electric signal even if there is friction. In other words, the driving force increases up to a certain range when it is delayed from the position where it is originally positioned with respect to a certain energized state, and the force to rotate to the original position is relatively large. For this reason, the effect of friction is smaller when simply rotating than when positioning and stopping at the original position as described above.

【0007】

In order to reduce the stop position error, it is sufficient to increase the driving force, but for that reason, it is necessary to pass a large amount of current through the coil, resulting in a large amount of power consumption and the disadvantage that the motor heats up and the characteristics deteriorate. There is.

【0008】

When using the microstep drive method to drive a lens or other object with a step motor and stop and hold the rotor of the step motor at a position corresponding to the energizing current to the coil, the backlash or friction of the gear or screw reduction device There is a drawback that the stop position varies due to the inertial friction of the moving part.

【0009】

[Means for solving problems]

The present invention is a two-phase PM type step motor drive device as a microstep drive table composed of a combination of PWM values for energizing each phase by changing the current value by the PWM method. A storage means for storing the first microstep drive table, a calculation means for performing an operation by the first function on the value of the first microstep drive table, and a setting means for setting the number of drive steps of the stepping motor. According to the first function with respect to the values of the first microstep drive table and the first microstep drive table by the arithmetic means according to the area of the steps set by the setting means. It is characterized in that it is provided with a control circuit capable of microstep driving by selecting either one of the microstep driving tables after performing the calculation.

【0010】

According to this, power consumption is suppressed by driving using a microstep drive table with a small PWM value for normal rotary drive, and heat generation of the motor is also suppressed. In the step immediately before stopping, a microstep drive table with a large PWM value is used. By using and driving, it becomes possible to increase the driving force and improve the stopping accuracy.

【0011】

Further, the present invention is a storage means for storing a first microstep drive table as a microstep drive table composed of a combination of PWM values for performing microstep drive energization by changing the current value by the PWM method in each phase. And a calculation means for performing an operation by the first function on the value of the first microstep drive table, and a setting means for setting the number of drive steps of the step motor, which are set by the setting means. Of the microstep drive table after performing the calculation by the first function on the values of the first microstep drive table and the first microstep drive table by the calculation means according to the area of the steps. It is characterized by comprising a step motor drive device provided with a control circuit capable of microstep drive by selecting either one, a step motor driven by the step motor drive device, and a lens driven by the step motor. It is a lens moving device.

【0012】

According to this, power consumption is suppressed by driving using a microstep drive table with a small PWM value for normal rotary drive, and heat generation of the motor is also suppressed. In the step immediately before stopping, a microstep drive table with a large PWM value is used. It is possible to increase the driving force and improve the stopping accuracy by driving using the step motor, and the lens and other things are driven by the step motor using the micro step drive method, and the step motor is positioned at the position corresponding to the energizing current to the coil. When the rotor is stopped and held, the defect that the stop position varies due to the backlash of the gear or screw speed reducer and the inertial friction of the sliding part can be minimized, and the position consumes less power. It can be a lens moving device with high output accuracy.

【0013】

BEST MODE FOR CARRYING OUT THE INVENTION

1 to 12 are the driving devices of the stepping motor of the first embodiment, FIG. 1 is a block diagram of the electric circuit of the driving device, and FIG. 2 is an exploded perspective view of the step motor used in the present embodiment. FIG. 3 is a sectional view in the axial direction after assembling the step motor, and FIG. 4 is a sectional view taken along line AA and a sectional view taken along line BB in FIG. FIG. 5 is a diagram showing the relationship between the energizing current to the coil during the full step and the elapsed time, and FIGS. 6 and 7 are diagrams showing the relationship between the energizing current to the coil during the micro step and the position of the rotor. FIG. 8 is a flowchart showing the operation of the control circuit. FIG. 9 is a diagram showing the state of energization current in both the microstep drive mode and the full step drive mode. FIG. 10 is a diagram showing the state of the energizing current when switching from the full step drive mode to the micro step drive mode. FIG. 11 is an exploded perspective view of the lens moving device including the step motor and the step motor driving device when the driven object is a lens. FIG. 12 is a perspective external view when applied to a pickup device for reading or writing information on a magneto-optical disk.

【0014】

In FIG. 1, M is a step motor, 1 is a drive circuit, 2 is a control circuit, 3 is a memory (storage means), 4 is an indicator, and 5 is a calculation means. The drive circuit 1 is for passing the energizing current specified by the control circuit 2 to the coil of the motor M. For example, the drive circuit 1 is composed of four transistors and can selectively energize the coil in both the forward and reverse directions. It consists of a circuit that has as many circuits as the number of phases of the coil. In this embodiment, since the explanation uses a two-phase stepping motor, at least two H circuits are provided. The indicator 4 inputs the rotation direction of the motor and the drive amount (number of steps) to the control circuit 2.

【0015】

The drive circuit in the claim is composed of the control circuit 2 and the drive circuit 1. The memory 3 is composed of a non-volatile memory and will be described in detail later with reference to FIG. 6. The memory 3 is a first microstep drive consisting of a combination of PWM values that energize each phase of the coil of the step motor M. The table is memorized. The calculation means 5 is composed of a microcomputer and hard logic, and the first function and the second function are stored. The first function or the second function calculates the PWM value of the first microstep drive table. It is a different value. The first function calculates the PWM value of the first microstep drive table. In this embodiment, it is a function that roughly increases the PWM value of the first microstep drive table. For example, a number exceeding 1 for all values. There is something like multiplying by. The number to be multiplied may be a fixed value, for example 1.5, or the PWM value of the first microstep drive table is generally multiplied by a value greater than 1 in one predetermined range but less than or equal to 1 in another range. It may be a function that roughly increases the size. The second function calculates the PWM value of the first microstep drive table. In this embodiment, it is a function that roughly reduces the PWM value of the first microstep drive table. For example, a number less than 1 for all values. There is something like multiplying by. The number to be multiplied may be a fixed value, for example 0.5, or the PWM value of the first microstep drive table is generally multiplied by a value that exceeds 1 in one predetermined range but less than 1 in another range. It may be a function that makes it roughly smaller. This situation is shown in FIGS. 7 (a) and 7 (b). FIG. 7 (a) is a microstep drive table after the first microstep drive table is calculated by the calculation means 5 by the first function, and FIG. 7 (b) is the first microstep drive table by the calculation means 5. Is a microstep drive table after calculating by the second function.

【0016】

In this embodiment, the PWM value of the microstep drive table calculated by the first function of the first microstep drive table is larger than that of the first microstep drive table, so that the first function When the microstep drive table calculated in is used, the current consumption is large but the driving force is also large. In addition, the microstep drive table calculated by the second function of the first microstep drive table has a smaller PWM value as a whole than the first microstep drive table, so the micro calculated by the second function. When the step drive table is used, the current consumption is smaller but the driving force is smaller than when the first micro step drive table and the micro step drive table calculated by the first function are used.

【0017】

The control circuit 2 sends a signal to the drive circuit 1 so as to drive the motor M by the amount of drive input from the indicator 4, but at that time, the first microstep stored in the memory 3 according to the step range. The drive table after the first microstep drive table by the first function is calculated via the drive table or the calculation means 5, or the first microstep drive table by the second function is calculated via the calculation means 5. After that, either of the drive tables is selected, and the drive circuit 1 is driven so as to energize the coils of each phase with a combination of PWM values according to the selected table.

【0018】

The stepping motor used in this embodiment is a motor known in Japanese Patent Application Laid-Open No. 9-331666. In FIGS. 2 to 4, reference numeral 11 denotes a cylindrical magnet constituting the rotor of the motor, that is, the rotor, and the magnet 11 which is the rotor divides the outer peripheral surface into n in the circumferential direction (in this embodiment). (Divided into 4) S poles and N poles are alternately magnetized as magnetized parts 11a, 11b, 11c and 11d, and these magnetized parts 11a and 11b are magnetized to the S pole and magnetized parts 11b and 11d. Is magnetized to the north pole.

【0019】

Reference numeral 17 denotes an output shaft serving as a rotor shaft, and the output shaft 17 is fixed to a magnet 11 which is a rotor. The rotor is composed of these output shafts 17 and magnets 11.

【0020】

Reference numerals 12 and 13 are cylindrical coils, the coils I2 and 13 are arranged concentrically with the magnet 11 and at positions sandwiching the magnet 11 in the axial direction, and the outer diameters of the coils 12 and 13 are outside the magnet 11. It is almost the same size as the diameter.

【0021】

18 and 19 are the first and second stators made of soft magnetic material, and the phases of the first stator 18 and the second step 19 are 180 / n degrees, that is, 45 ° out of phase, and these are arranged. The first stator 18 and the second stator 19 are composed of an outer cylinder and an inner cylinder.

【0022】

A coil 12 is provided between the outer cylinder and the inner cylinder of the first stator 18, and the first stator 18 is excited by energizing the coil 12. The outer cylinder and inner cylinder of the first stator 18 have outer magnetic poles 18a and 18b and inner magnetic poles 18c and 18d at their tips, so that the inner magnetic poles 18c and inner magnetic poles 18d are in phase with each other. It is formed with a phase of 360 / (n / 2) degrees, that is, 180 degrees, and the outer magnetic pole 18a is arranged to face the inner magnetic pole 18c, and the outer magnetic pole 18b is arranged to face the inner magnetic pole 18d.

【0023】

The outer magnetic poles I8a, 18b and the inner magnetic poles 18c, 18d of the first stage 18 are provided so as to face the outer peripheral surface and the inner peripheral surface on one end side of the magnet 11 and sandwich one end side of the magnet 11. Further, one end of the rotating shaft 17 is rotatably fitted in the hole 18e of the first stator 18.

【0024】

A coil 13 is provided between the outer cylinder and the inner cylinder of the second stator 19, and the second stator 19 is excited by energizing the coil 13. The outer and inner cylinders of the second stator 19 have outer magnetic poles 19a and 19b and inner magnetic poles 19a and 19b at their tips, and the outer magnetic poles 19a and 19b and the inner magnetic poles 19c and 19d are other than the permanent magnets 11. It is provided so as to face the outer peripheral surface and the inner peripheral surface on the end side and sandwich the other end side of the permanent magnet 11. Further, the other end of the rotating shaft 17 is rotatably fitted in the hole 19e of the second stator 19.

【0025】

Therefore, the magnetic flux generated by the coil 12 crosses the magnet 11 which is a rotor between the outer magnetic poles 18a and 18b and the inner poles 18c and 18d, so that it effectively acts on the magnet 11 which is a rotor and the magnetic flux generated by the coil 13. Crosses the rotor magnet between the outer poles 19a and 19b and the inner poles 19c and 19d, effectively acting on the rotor magnet 11 and increasing the motor output.

【0026】

Reference numeral 20 denotes a connecting ring as a cylindrical member made of a non-magnetic material. Grooves 20a and 20b are provided on one end side of the inside of the connecting ring 20 and the phase is 45 degrees with respect to the grooves 20a and 20b on the other end side. The shifted grooves 20c and 20d are provided, and the outer magnetic poles 18a and 18b of the first stator 18 are fitted into the grooves 20a and 20b, and the outer magnetic poles 19a and 19b of the second stator 19 are fitted into the grooves 20c and 20d. Then, these fitting portions are fixed with an adhesive, and the first stator 18 and the second stator 19 are attached to the connecting ring 20.

【0027】

The first stator 18 and the second stator 19 face each other with the tips of the outer poles 18a, 18b and the inner poles 18c, 18d and the tips of the outer poles 19a, 19b and the inner poles 19c, 19d, and the outer poles 18a, 18a, The 18b and the outer magnetic poles 19a and 19b are fixed to the continuous ring 20 with a width of the protrusions 20e and 20f on the inner surface side of the connecting ring 20.

【0028】

FIG. 3 is a cross-sectional view of the step motor, FIGS. 4 (a), (b), (c), and (d) show a cross-sectional view taken along the line AA of FIG. ), (G), and (h) are cross-sectional views taken along the line BB in FIG. (A) and (e) in FIG. 4 are sectional views at the same point, (b) and (f) in FIG. 4 are sectional views at the same point, and (c) and (c) in FIG. g) is a cross-sectional view at the same point, and (d) and (h) in FIG. 4 are cross-sectional views at the same point.

【0029】

Next, the operation of this step motor will be described. From the states (a) and (e) of FIG. 4, the coils 12 and 13 are energized, the outer magnetic poles 18a and 18b of the first stator 18 are N poles, the inner magnetic poles 18c and 18d are S poles, and the second When the outer magnetic poles 19a and 19b of the stator 19 are set to the S pole and the inner magnetic poles 19c and 19d are excited to the N pole, the magnet 11 which is a rotor rotates 45 degrees counterclockwise, and (b) and (f) in FIG. ) Will be displayed.

【0030】

Next, the energization to the coil 12 is reversed, the two outer magnetic poles 18a and 18b of the first stator 18 are set to S poles, the inner magnetic poles 18c and 18d are set to N poles, and the outer magnetic poles 19a and 19b of the second stator 19 are set. When the inner magnetic poles 19c and 19d are excited to the N pole, the magnet 11 which is a rotor is further rotated 45 degrees counterclockwise to be in the state shown in (c) and (g) of FIG.

【0031】

Next, the energization to the coil 13 is reversed, the outer magnetic poles 19a and 19b of the second stator 19 are N poles, the inner magnetic poles 19c and 19d are S poles, and the outer magnetic poles 18a and 18b of the first stator 18 are S. When the inner magnetic poles 18c and 18d are excited to the north pole and the inner magnetic poles 18c and 18d are excited to the north pole, the magnet 11 which is a rotor is further rotated 45 degrees counterclockwise to be in the state shown in (d) and (h) of FIG.

【0032】

After that, by sequentially switching the energizing directions of the coil 12 and the coil 13 in this way, the magnet 11 which is a rotor rotates to a position corresponding to the energizing phase. On the contrary, from the states shown in (d) and (h) of Fig. 4, (c) and (g) of Fig. 4, (b) and (f) of Fig. 4, and (a) and (e) of Fig. 4 The magnet 11 rotates clockwise by switching the energization of the coil to the state.

【0033】

The above is the explanation of the full-step drive in which the energization of the coils 12 and 13 is switched at a constant value. The state of the energizing current to the coils 12 and 13 at this time is shown in FIGS. 5 (a) and 5 (b). FIG. 5 (a) shows the state of energization of the coil 12, and FIG. 5 (b) shows the state of energization of the coil 13. There is a microstep drive method in which the rotor, that is, the magnet 11 is stopped at a position between the positions shown in FIG. 4 by changing the ratio of the current values energizing the coils 12 and 13, but in the present invention, the following is particularly true. Energize like.

【0034】

FIG. 6 is a diagram showing the relationship between the energizing currents of the coils 12 and 13 and the number of steps when energization is performed based on the first microstep drive table stored in the memory 3. In the memory 3, as the first microstep drive table, the current value of energizing the coils 12 and 13 of (A1, B1), (A2, B2), (A3, B3), ..., (Am, Bm) A table showing the ratio is stored. Al, A2, A3, ..., Am are the ratios of the current values that energize the coil 12, and B1, B2, B3, ..., Bm are the ratios of the current values that energize the coil 13. There is a pulse width modulation method (PWM control method) of the applied voltage as a method of changing the current value, and in the case of such an energization method, the value stored in the first microstep drive table is the energization duty value. The data is stored.

【0035】

FIG. 7 (a) is a diagram showing the relationship between the energizing currents of the coils 12 and 13 and the number of steps when the first microstep drive table is energized based on the microstep drive table calculated by the first function. is there. Fig. 7 (b) is a diagram showing the relationship between the energizing current of the coils 12 and 13 and the number of steps when the first microstep drive table is energized based on the microstep drive table calculated by the second function. is there. The PWM value of the microstep drive table calculated by the first function of the first microstep drive table shown in Fig. 7 (a) is larger than that of the first microstep drive table. When the microstep drive table calculated by the function of is used, the current consumption is large but the driving force is also large. Since the PWM value of the microstep drive table obtained by calculating the first microstep drive table shown in Fig. 7 (b) by the second function is smaller than that of the first microstep drive table, the second one. When the microstep drive table calculated by the function of is used, the current consumption is lower than when the first microstep drive table and the first microstep drive table are calculated by the first function. It is small, but the driving force is also small.

【0036】

In memory 3, the current value that energizes the coils 12 and 13 of (C1, Dl), (C2, D2), (C3, D3), ..., (Cm, Dm) as the second microstep drive table. A table showing the ratio of is stored. C1, C2, C3, ..., Cm are the ratios of the current values that energize the coil 12, and Dl, D2, D3, ..., Dm are the ratios of the current values that energize the coil 13. The calculation means 5 stores the first function and the second function, and the first function calculates the PWM value of the first microstep drive table. In this embodiment, the first microstep drive table is calculated. This is a function that roughly increases the PWM value of, and in this example, a function that multiplies all values by a number exceeding 1, specifically 1.5, is used. For example, as shown in Fig. 6, the first microstep drive table is set so that the maximum values A5, A6 or B10, B11, etc. are set to 60%, but the second microstep drive table is shown in Fig. 7 ( As shown in a), the maximum values C5, C6 or D10, D11, etc. are set to be 90%. Therefore, the microstep drive table calculated via the first function shown in Fig. 7 (a). When is used, the current consumption is large, but the driving force is also large.

【0037】

The second function of the calculation means 5 calculates the PWM value of the first microstep drive table, and in this embodiment, it is a function that substantially reduces the PWM value of the first microstep drive table. We use a function that multiplies all values by a number less than 1, specifically 0.8. For example, as shown in Fig. 6, the first microstep drive table is set so that the maximum values A5, A6 or B10, B11, etc. are set to 60%, but the second microstep drive table is shown in Fig. 7 ( As shown in b), the maximum values E5, E6 or F10, F11, etc. are set to 42%. Therefore, the microstep drive table calculated via the second function shown in Fig. 7 (b). The driving force is small, but the current consumption is also small.

【0038】

Of course, the numerical value to be multiplied does not have to be a constant value for both the first function and the second function, and a method of adding or subtracting rather than multiplying a certain numerical value may be used. In other words, it does not limit the types of functions, and when the first microstep drive table is operated by the first function, it is not always necessary that all the values are increased by the operation by the first function. It suffices if the duty value has a larger absolute value than that of the first microstep drive table. Similarly, when the first microstep drive table is calculated by the second function, it is not always necessary that all the values are reduced in absolute value by the operation by the second function. It suffices if the duty value must be smaller than the drive table in absolute value.

【0039】

When comparing the value of (Cm, Dm) and the value of (Am, Bm), the absolute value of (Cm, Dm) is set larger than the absolute value of (Am, Bm), and at that time. The value of Cm / Dm, which is the energization ratio of coil 12 to coil 12, and Am / Bm are almost the same value, but they do not always match, that is, Cm is tentatively 1.5 times the value of Am. However, Dm is not always 1.5 times that of Bm.

【0040】

The value of Cm / Dm, which is the ratio of energization to coil 13 to coil 12, and Am / Bm are almost the same value, but they are set so that they do not always match the energization at (Cm, Dm) and (Am, Dm). This is so that the rotor position is the same when the power is applied at Bm). The rotation position of the rotor is determined by the combined force of the force attracted by the rotor magnet to the stators 18 and 19 and the magnetic force generated by energizing the coils 12 and 13. Since the absolute value of the combination of (Cm, Dm) is set to be larger than that of the combination of (Am, Bm), the magnetic force generated by energizing the coils 12 and 13 becomes larger. As a result, the ratio of the force attracted by the rotor magnet to the stators 18 and 19 and the magnetic force generated by energizing the coils 12 and 13 also changes. However, the rotation position of the rotor is different from the case of energization of the combination of (Am, Bm). The value of Cm / Dm is set to a value different from the value of Am / Bm by adding the force that the rotor magnet attracts to the stators 18 and 19 so that the rotation position of the rotor is the same position as the energization of (Am, Bm). It has been set. The same can be said for the value Em / Fm calculated via the second function.

【0041】

In this embodiment, the magnet 11 which is a rotor switches the energization of the coils 12 and 13 according to (Al, B1), (A2, B2), (A3, B3), ..., (Am, Bm). By performing 2 cycles, it makes one rotation counterclockwise. Alternatively, the energization of the coils 12 and 13 can be switched according to (C1, Dl), (C2, D2), (C3, D3), ..., (Cm, Dm) for two cycles in the clockwise direction. Rotate. For example, if m is 20, the magnet 11 that is a rotor makes one rotation in 40 steps.

【0042】

Next, switching between full-step drive and micro-step drive will be described. The rotation speed and output torque of the motor are higher in the full-step drive than in the micro-step drive, and the rotation resolution of the output shaft of the motor is naturally higher in the micro-step drive than in the full-step drive. For this reason, when positioning the object to be driven at a predetermined position, if it is far from the target position, it is driven at high speed with full step drive, and if it is near the target position on the way, it is driven with micro step drive to a precise position. High-speed and high-precision positioning can be achieved by positioning. Alternatively, in order to smooth the start of movement, the speed is gradually increased by microstep drive at low speed from the start of movement, and the driven object is smoothed by taking a method of driving at higher speed by full step drive from a predetermined speed or higher. It can be driven at high speed.

【0043】

In this embodiment, the start of driving is gradually accelerated by microstep driving, and after exceeding a predetermined speed or a predetermined number of pulses, it is driven by full step driving and further driven at a higher speed. Then, when it approaches the target position by a predetermined amount, it is driven again in the microstep drive mode to perform precise positioning.

【0044】

FIG. 9 is a diagram showing the state of energization current in both the microstep drive mode and the full step drive mode. Switching from microstep drive to full step drive or switching from full step drive to microstep drive is performed at the timing when the absolute value of the energizing current of each phase at the time of microstep energization becomes the same. That is, the timings of a, b, c, and d in FIG. That is, it is the timing when the absolute value of the energizing current of each phase at the time of microstep energization becomes the same or substantially the same. For example, the state of the energizing current when switching from full-step drive to micro-step drive at the timing of b is shown in FIG.

【0045】

The microstep drive table is not always a combination table in which the absolute values of the energizing currents of each phase exactly match when the energizing current changes stepwise except when the energizing current changes continuously. In this case, the timing is such that the absolute values of the energizing currents of each phase are substantially the same.

【0046】

At these timings, the ratio of the energizing current to the two coils is 1: 1 or approximately 1: 1 and the rotor rotation position changes due to the switching of the drive mode because it is the same or almost the same during full step and micro step. Absent. As a result, even if the drive mode is changed from full-step drive to micro-step drive or from micro-step drive to full-step drive, the rotation shifts smoothly, so the mode changes smoothly as described in the conventional example. It is no longer possible to drive the driven object smoothly at high speed or to be unable to perform high-speed and high-precision positioning due to vibration or step-out caused by not doing so. ..

【0047】

The operation of the control circuit 4 will be described with reference to the flowchart of FIG. Step 1: Accept the instructed information (rotation direction and number of steps) from the instruction unit 4. Step 2: Read the first microstep drive table stored in memory 3 and proceed to step 3.

【0048】

The microstep drive table in which the first microstep drive table and the first microstep drive table are calculated by the first function and the microstep drive table in which the first microstep drive table is calculated by the second function are previously It is a table that gives the current value as shown in Fig. 6 and Fig. 7 described above. When the combination of PWM values of the microstep drive table calculated by the second function is expressed as (Em, Fm), they are compared with the values of the microstep drive table (Cm, Dm) calculated by at least the first function. If so, the table of values is such that the absolute value of the current is smaller than the current flowed by (Cm, Dm). Once positioned by microstep drive, the state is tried to be maintained by the load of friction, the energization to the coil is reduced, the magnetic force by the coil weakens, and the ratio of the attractive force between the magnet and the stator increases, but it exceeds a certain level Once the electromagnetic force is generated, the magnet rotor is held at the position once positioned. If only the magnet rotor once positioned in this way is considered, the frictional force works to hold it at that position, so that the current can be reduced, the current consumption can be suppressed, and the heat generated by the motor can be reduced. Effective in prevention.

【0049】

Step 3: If the number of steps of the information received from the instruction unit 4 is the predetermined value M or more, the process proceeds to step 9, and if the number of steps is less than the predetermined value M, the process proceeds to step 4. The predetermined value in this embodiment is a value larger than the number of steps of microstep drive plus 2 pulses corresponding to the amount of rotation for one step of full step drive, that is, a value larger than 7 of 5 + 2. It is set to. If the predetermined value M is set to 7, and the feed amount is 6 steps or less, the process proceeds to step 4 assuming that there are not enough steps to switch to full step drive.

【0050】

Step 4: If the number of remaining driving steps is 2 or more in the micro step, proceed to step 5, and if the number of remaining steps is 1 step, proceed to step 6.

【0051】

Step 5: Drive the drive circuit 1 so as to rotate in a predetermined direction based on the information received from the indicator 4 according to the first microstep drive table read from the memory 3.

【0052】

As described above, the first microstep drive table consumes less current than the case where the first microstep drive table is driven according to the calculated microstep drive table by the first function of the arithmetic means 5, and the drive thereof is also smaller. The power is also small. When the stepping motor is delayed from the position where it is originally positioned with respect to a certain energized state, the driving force increases up to a certain range and the force for rotating to the original position is relatively large. Here, since the phase delay with respect to the electric signal of the rotor can be tolerated to some extent, the drive can be performed even if the current consumption is set to be small. Since the current consumption is small, the drive has low power consumption and prevents heat generation.

【0053】

Step 6: The last one step is rotated in a predetermined direction based on the information received from the indicator 4 according to the microstep drive table in which the first microstep drive table is calculated by the first function of the calculation means 5. Drive circuit 1 as described above. In this case, since the final stop position is determined by this operation, accurate positioning of the rotor according to the electric signal is required. As mentioned above, the closer the position of the rotor is to the position where it is originally positioned by microstep control, the smaller the rotational driving force generated when trying to position it at that original position, and there is only a slight frictional force. It becomes difficult to position it in its original position. Therefore, only this step is driven according to the microstep drive table calculated by the first function of the calculation means 5, but the microstep drive table calculated by this first function is the first. The PWM value is generally larger than that of the microstep drive table in. Therefore, when the second microstep drive table is used, the current consumption is large but the driving force is also large, so that the rotor can be positioned at an accurate position according to the electric signal.

【0054】

The combination of the PWM values (Cm, Dm) of the microstep drive table calculated by the first function of the first microstep drive table is the combination of the PWM values (Am, Bm) of the first microstep drive table. Since the absolute value is set to be larger than the energization of, the magnetic force generated by energizing the coil 12 and the coil 13 becomes large. As a result, the ratio of the force attracted by the rotor magnet to the stators 18 and 19 and the magnetic force generated by energizing the coils 12 and 13 also changes, so the rotation position of the rotor is the same as the energization of (Am, Bm). The ratio of each phase of the PWM value of the microstep drive table calculated by the first function by adding the force that the rotor magnet attracts to the stators 18 and 19 so that it is in the position Cm / The value of Dm is set to a value different from the value of Am / Bm, which is the ratio of each phase of the PWM value of the first microstep drive table.

【0055】

In addition, driving this first microstep drive table according to the PWM value of the microstep drive table calculated by the first function has a large driving force due to the large current consumption, and the correct position even if there is friction. Although the magnet rotor can be positioned in, there is a concern that heat generation and power consumption will increase, but this will be resolved by step 8 described later.

【0056】

Step 7: Drive the last step and proceed to step 8 when sufficient time has passed for the magnet rotor to be positioned and stabilized in its energized state.

【0057】

Step 8: The magnet rotor located in step 6 is energized by microstepping the first microstep drive table stored in the memory 3 according to the microstep drive table calculated by the second function of the calculation means 5. Hold the rotation position.

【0058】

When the combination of PWM values of the microstep drive table calculated by the second function of the arithmetic means 5 is expressed as (Em, Fm), they are at least the first microstep drive table (Em, Fm). When the value of Am, Bm) or the first microstep drive table is compared with the value of the microstep drive table (Cm, Dm) calculated by the first function, it is flowed by (Am, Bm) or (Cm, Dm). It is a table of values in which the absolute value of the current is smaller than the current. Once positioned by microstep drive, the state is tried to be maintained by the load of friction, the energization to the coil is reduced, the magnetic force by the coil weakens, and the ratio of the attractive force between the magnet and the stator increases, but it exceeds a certain level. Once the electromagnetic force is generated, the magnet rotor is held at the position once positioned. If only the magnet rotor once positioned in this way is considered, the frictional force works to hold it at that position, so that the current can be reduced, the current consumption can be suppressed, and the heat generated by the motor can be reduced. Effective in prevention.

【0059】

In this step, the fixed quantity rotation is completed in a predetermined direction based on the information received from the indicator unit 4, and the device is in a state of waiting for the next operation.

【0060】

Step 9: Drive the drive circuit 1 so as to rotate a predetermined amount in a predetermined direction based on the information received from the indicator 4 according to the first microstep drive table read from the memory 3.

【0061】

Step 10: The timing of a, b, c, d in Fig. 9 during the microstep drive started from step 9, that is, the timing when the absolute value of the energizing current of each phase becomes the same when the microstep is energized, or e in Fig. 6. If it is determined whether or not the energized state is reached at any of the timings of, f, g, and h, that is, the timing at which the absolute values of the energizing currents of each phase are substantially the same, the process proceeds to step 11.

【0062】

Step 11: Switch the motor drive mode from microstep drive to full step drive. At the time of proceeding to step 11, the motor is sufficiently accelerated and the driven object (not shown) is smoothly accelerated. From now on, the motor will be driven by full-step drive that can drive with sufficiently high output torque and high rotation speed.

【0063】

At this timing, the ratio of the energizing current to the two coils is 1: 1 or approximately 1: 1 and is the same or almost the same during full step and micro step, so the rotor rotation position does not change due to switching of the drive mode. .. As a result, even if the drive mode is changed from micro-step drive to full-step drive, the rotation shifts smoothly, so vibration occurs due to the lack of smooth change as explained in the conventional example due to mode switching. It is no longer possible to drive the object to be driven smoothly at high speed or to perform high-speed and high-precision positioning due to step-out or step-out.

【0064】

Step 12: If the number of remaining steps in the microstep drive is equal to or less than the predetermined value P for the information received from the indicator or 4, the process proceeds to step 13. The predetermined value in this embodiment is the number obtained by adding one pulse or more to the number of steps of microstep drive corresponding to the amount of rotation for one step of full step drive, that is, 5 + 1, and the remaining steps are 6 even at this point. It's more than a step. That is, the predetermined value P is set to a numerical value of at least 6 or more.

【0065】

Step 13: Timing of energization phases a, b, c, d in Fig. 9, that is, timing when the absolute values of energization currents of each phase become the same during microstep energization, or timing of e, f, g, h in Fig. 6. That is, when any of the timings at which the absolute values of the energizing currents of each phase are substantially the same is reached, the process proceeds to step 14. Step 14: Switch the full step drive started from step 11 to the micro step drive. The switching of microstep drive is the same as the energization phase of the coil in full step drive at that time, and the timing of a, b, c, d in Fig. 9, that is, the absolute value of the energization current of each phase during microstep energization is the same. It starts from either the timing of becoming or the timing of e, f, g, h in FIG. 6, that is, the timing at which the absolute values of the energizing currents of each phase are approximately the same, and the energizing currents at that time are read out from the memory 3. According to the first microstep drive table, the drive circuit 1 is driven so as to rotate by energizing the microstep.

【0066】

At this timing, the ratio of the energizing current to the two coils is 1: 1 or approximately 1: 1 and is the same or almost the same during full step and micro step, so the rotor rotation position does not change due to the switching of the drive mode.

【0067】

As a result, even if the drive mode is changed from full step drive to micro step drive, the rotation shifts smoothly, so vibration occurs due to the smooth change as explained in the conventional example due to mode switching. It is no longer possible to drive the object to be driven smoothly at high speed or to perform high-speed and high-precision positioning due to accidental step-out or step-out.

【0068】

In step 10, the timing of a, b, c, d in FIG. 9, that is, the timing at which the absolute values of the energizing currents of each phase become the same during microstep energization, or the timing of e, f, g, h in FIG. 6, that is, each. It is not always the timing when the energization state is reached at any of the timings when the absolute values of the energization currents of the phases are approximately the same, but it is not necessarily the timing when the energization state is started from the start of the drive. It may be the timing of a, b, c, d or the evening iming of e, f, g, h after the driving object is smoothly accelerated to a predetermined speed. That is, what is necessary is that the timing of shifting from the microstep drive to the full step drive is the timing at which the absolute values of the energizing currents of each phase are the same or substantially the same.

【0069】

In step 13, switching from full-step drive to micro-step drive has the same number of steps remaining as 6 pulses or more, which is the same as the energization phase of the coil in full-step drive at that time, and a, b, c, d in FIG. Timing, that is, the timing at which the absolute values of the energizing currents of each phase become the same during microstep energization, or the timing of e, f, g, h in Fig. 6, that is, the timing at which the absolute values of the energizing currents of each phase become approximately the same. It starts from either one, but what is necessary is that the timing of transition from full-step drive to micro-step drive is the timing at which the absolute values of the energizing currents of each phase are the same or approximately the same.

【0070】

At this timing, the ratio of the energizing current to the two coils is 1: 1 or approximately 1: 1 and the rotor rotation position does not change due to the switching of the drive mode because it is the same or almost the same during full step and micro step. .. As a result, even if the drive mode is changed from full-step drive to micro-step drive or from micro-step drive to full-step drive, the rotation shifts smoothly. Even if the drive mode is switched between full-step drive and micro-step drive, vibration does not occur or step-out occurs due to the smooth change as described in the conventional example. As a result, the object to be driven can be smoothly driven at high speed and can be positioned at high speed and with high accuracy.

【0071】

As described above, the first microstep drive table and the first microstep drive table are set by the first function according to the area of the steps set by the setting means for setting the number of drive steps of the stepping motor. By selecting either of the calculated microstep drive tables and enabling microstep drive, it is possible to position the magnet rotor in the correct position while minimizing power consumption and heat generation. It was.

【0072】

FIG. 11 is an exploded perspective view of the lens moving device including the step motor and the step motor driving device when the driven object is a lens.

【0073】

In this figure, reference numeral 51 denotes a frame formed by bending into a U shape, and the end portions of the main body portion (stator, which will be described later) of the step motor M are fitted into the holding holes 51a and 51b formed at both ends of the frame 51. It will be retained. Reference numeral 52 denotes a pinion gear, which is fixed to the output shaft 17 of the step motor M. Reference numeral 53 denotes a lead screw shaft (drive shaft), and a lead screw portion 53a having a length equivalent to the length of the main body portion of the step motor M is formed. The lead screw shaft 53 is rotatably fitted and held in holding holes 51d and 51c formed at both ends of the frame 51. In this way, the step mode M and the lead screw shaft 53 are arranged by the frame 51 so that the output shaft 7 and the lead screw shaft 53 extend in parallel with each other in the radial direction (so-called parallel).

【0074】

Further, a gear portion 53b is provided at one end of the lead screw shaft 53, and this gear portion 53b meshes with the pinion gear 52. Therefore, when the step motor M rotates, the lead screw shaft 53 is rotationally driven. The gear portion 53b and the pinion gear 52 constitute the transmission means according to the claims.

【0075】

Reference numeral 54 denotes an L-shaped leaf spring, the base end portion 54b is fixed to the frame 51, and the springy arm portion 54b presses the end portion 53c of the lead screw shaft 53. As a result, the lead screw shaft 53 is offset with respect to the frame 51, and backlash in the thrust direction between them is prevented. 56 is a lens, and 55 is a lens holder (driven body) that holds the lens 56. The lens holder 56 is provided with a contact portion 55a on which a female screw is formed, and the contact portion 55a (female screw) is in contact (engagement) with the lead screw portion 53a of the lead screw shaft 53. Further, the lens holder 55 is formed with a guide hole portion 55b and a steady rest groove portion 55c, which are slidably fitted with guide rods 57 and 58 held on a main plate (not shown), respectively. Therefore, the lens holder 55 is guided in the optical axis direction in a state where the rotation around the optical axis is restricted by the guides 57 and 58.

【0076】

In the lens driving device configured in this way, when the lead screw shaft 53 rotates due to the rotation of the step motor M, the lens holder 55 receives an axial driving force from the lead screw portion 53a at the contact portion 55a, and the amount of rotation of the step motor M. And, it moves in the optical axis direction together with the lens 56 according to the rotation direction.

【0077】

Here, as described above, since the output shaft 7 and the lead screw shaft 53 are arranged in parallel in the step motor M and the lead screw shaft 53, the step motor M and the lead screw shaft 53 are arranged in series. Compared with such a case, the total length of the device can be shortened. Moreover, despite the short overall length of the device, most of the length is used to make the length of the lead screw shaft 53 equal to or longer than that when arranged in series (that is, the length of the lead screw portion 53a). Can be secured. Therefore, the moving range of the lens 56 can be set large.

【0078】

Further, since the length of the step motor M has a layout that has almost no effect on the length of the lens driving device, it is possible to increase the size of the step motor and increase the driving force.

【0079】

When the stepping motor M is driven by microstep drive to position the lens holder 55 and the lens 56 at a fine pitch along the optical axis, they are driven by the step motor drive circuit described in the first embodiment. When the lens holder 55 and the lens 56 are driven counterclockwise of the step motor M and displaced so as to be in a predetermined position, the combination of PWM values determined by the data stored in the first microstep drive tedel is used. When the step motor M is driven and the step motor M is driven clockwise to displace the lens holder 55 and the lens 56 so as to be in a predetermined position, the data stored in the second microstep drive table is used. The step motor M is driven by the combination of the determined PWM values.

【0080】

As a result, when the lens holder 55 and the lens 56 are displaced so as to be in the predetermined positions, the rotation positions of the rotor of the step motor M, that is, the magnet 11, are stopped clockwise and counterclockwise. Is slightly different. Depending on the amount of the stop position, the lens holder 55 has a backlash between the contact portion 55a and the lead screw portion 53a of the lead screw shaft 53, or the backlash between the gear portion 53b of the lead screw shaft 53 and the pinion gear 52, and the inertia of the sliding portion of the lens holder 55. The influence of friction is canceled, and the lens holder 55 and the lens 56 are positioned at predetermined positions even when stopped from any rotation direction, resulting in a highly accurate lens moving device.

【0081】

In addition, by switching between full-step drive and micro-step drive, highly accurate and high-speed lens positioning becomes possible, and even if the full-step drive to micro-step drive or micro-step drive to full-step drive drive mode is changed, it is smooth. The rotation shifts to. Full-step drive Even if the drive mode is switched between the icro-step drive, vibration does not occur or step-out occurs due to the smooth change as described in the conventional example. As a result, the lens to be driven can be smoothly driven at high speed and can be positioned at high speed and with high accuracy.

【0082】

The microstep drive is performed by selecting either the first microstep drive table or the second microstep drive table according to the area of the steps set by the setting means for setting the number of drive steps of the stepping motor. By making it possible, it has become possible to position the magnet rotor in an accurate position while minimizing power consumption and heat generation.

【0083】

In this embodiment, the structure is such that the lens is moved in the direction parallel to the optical axis, but the lens is arranged so as to move in the direction perpendicular to the optical axis direction of the lens, that is, for reading or writing information on the magneto-optical disk. It can also be applied to the pickup device of. The perspective external view in that case is shown in FIG.

【0084】

Reference numeral 100 denotes a magneto-optical disk, in which tracks for recording at intervals of several μm are formed, and a spot diameter of several μm is formed between the tracks by an optical beam to magnetically record information and optically reproduce the recorded information. It is a disk-shaped information recording medium.

【0085】

61 is a carriage and 62 is a pickup. The pickup 62 includes an irradiation light source, a light receiving element, and a lens that forms an image of reflected light on the light receiving element.

【0086】

63 is a guide shaft fixed to the main body at both ends, 64 is a slider fixed to the carriage 61 and slidably fitted to the guide shaft 63, M is a motor fixed to the main body, 66 is fixed to the output shaft of the motor M. The pinion gear 67 is a lead screw shaft rotatably attached to the main body side, and the lead screw portion 67A of the lead screw shaft is screwed with the female screw portion 61A of the carriage 61, and a hasba gear portion 67B is formed at one end. ing. Reference numeral 68 denotes a reduction gear consisting of a worm portion 68A and a crown gear portion 68B consisting of a disk and teeth, and is rotatably attached to the main body. The worm portion 68A of the reduction gear 68 meshes with the Hasuba gear portion 67B of the lead screw shaft 67. The crown gear portion 68B of the pinion gear 66 and the reduction gear 68 drives the meshing motor M, so that the carriage 61 and the pickup 62 are scanned in the arrow C direction along the magneto-optical disk 100.

【0087】

Reference numeral 69 denotes an ita spring whose one end is fixed to the carriage 61 and the other end presses the lead screw portion 67A of the lead screw shaft 67 to eliminate rattling between the female screw portion 61A of the carriage 61 and the lead screw group 67A. Reference numeral 70 denotes an electric control circuit, which is provided in the main body and includes at least the drive circuit 1, the memory 3, and the control circuit 2 shown in FIG. 71 is a flexible printed circuit board that electrically connects the pickup 62 and the electric control circuit 70. Reference numeral 72 denotes a flexible printed circuit board that electrically connects the motor M and the electric control circuit 70.

【0088】

The pickup 62 is scanned in the direction of arrow C along the optical disc 100 by the forward or reverse rotation of the motor M.

【0089】

[Effect of the invention]

As described in detail above, according to the present invention, in a drive device for a two-phase PM type step motor, a storage means for storing a first microstep drive table composed of a combination of PWM values that energize each phase. Of the calculation means for performing the calculation by the first function on the value of the first microstep drive table, the setting means for setting the number of drive steps of the stepping motor, and the steps set by the setting means. Select either the first microstep drive table or the microstep drive table after the calculation by the first function is performed on the value of the first microstep drive table by the calculation means according to the region of. By providing a control circuit that enables microstep drive, power consumption is suppressed and motor heat generation is suppressed by driving using a microstep drive table with a small PWM value in the normal rotation drive region, and immediately before stopping. In the steps in the area of, it is possible to increase the driving force and improve the stop accuracy by driving using the microstep drive table having a large PWM value calculated by the first function.

【0090】

Further, according to the present invention, in a drive device for a two-phase PM type step motor, a storage means for storing a first microstep drive table composed of a combination of PWM values that energize each phase, and the first. Depending on the calculation means that performs the calculation by the first function for the value of the microstep drive table of 1, the setting means that sets the number of drive steps of the stepping motor, and the area of the steps set by the setting means. Then, either the first microstep drive table or the microstep drive table after the calculation by the first function is performed on the values of the first microstep drive table by the calculation means is selected to perform microstepping. A lens moving device including a step motor drive device provided with a control circuit capable of driving, a step motor driven by the step motor drive device, and a lens driven by the step motor causes normal rotation. By using a microstep drive table with a small PWM value for driving, power consumption is suppressed and heat generation of the motor is also suppressed. In the step immediately before stopping, a microstep drive table with a large PWM value calculated by the first function is used. It is possible to increase the driving force and improve the stopping accuracy by driving using the step motor, and the lens and other things are driven by the step motor using the micro step drive method, and the step motor is positioned at the position corresponding to the energizing current to the coil. When the rotor of the motor is stopped and held, the defect that the stop position varies due to the backlash of the speed reducer of the gear or screw and the inertial friction of the sliding part can be minimized, and the position with low power consumption. It can be a lens moving device with high output accuracy.

[Simple explanation of drawings]

[Figure 1]

FIG. 1 is a block diagram of the electric circuit of the present invention.

[Figure 2]

FIG. 2 is an exploded perspective view of the step motor used in this embodiment.

[Fig. 3]

FIG. 3 is a cross-sectional view in the axial direction after assembling the step motor.

[Fig. 4]

FIG. 4 is a cross-sectional view taken along the line AA and a cross-sectional view taken along the line BB in FIG.

[Fig. 5]

FIG. 5 is a diagram showing the relationship between the energizing current to the coil and the elapsed time at the time of full step.

[Fig. 6]

FIG. 6 is a diagram showing the relationship between the energizing current to the coil and the number of steps when the first macro step drive table is used.

[Fig. 7]

FIG. 7A is a diagram showing the relationship between the energizing current to the coil and the number of steps when the microstep drive table calculated by the first function is used for the first macro step drive table. FIG. 7B is a diagram showing the relationship between the energizing current to the coil and the number of steps when the microstep drive table calculated by the second function is used for the first macro step drive table.

[Fig. 8]

FIG. 8 is a flowchart showing the operation of the control circuit.

[Fig. 9]

FIG. 9 is a diagram showing the state of energization current in both the microstep drive mode and the full step drive mode.

[Fig. 10]

FIG. 10 is a diagram showing the state of the energizing current when switching from the full step drive mode to the micro step drive mode.

[Fig. 11]

FIG. 11 is an exploded perspective view of the lens moving device including the step motor and the step motor driving device when the driven object is a lens.

[Fig. 12]

FIG. 12 is a perspective external view when applied to a pickup device for reading or writing information on a magneto-optical disk.

[Fig. 13]

FIG. 13 is a diagram showing a typical energization method of microstep drive.

[Fig. 14]

FIG. 14 is a diagram showing the state of the energizing current when switching from the conventional full-step drive to the micro-step drive.

[Fig. 15]

FIG. 15 is a cross-sectional view of the step motor.

[Fig. 16]

FIG. 16 is a diagram showing the relationship between the steering wheel and the rotor.

[Fig. 17]

FIG. 17 is a diagram showing the relationship between the stator and the rotor.

[Sharpness of sign]

1 drive circuit 2 control circuit 3 memory 4 Indicator 5 Computational means 11 Magnet 12 1st coil 13 Second coil 17 Output shaft 18 1st stator 19 Second stator 20 connecting ring M step motor