JP5885419B2 - Motor driving device and control method of motor driving device - Google Patents

Description

  The present invention relates to a motor driving device of a motor provided with position detection means and a method for controlling the motor driving device.

  The stepping motor has features such as small size, high torque, and long life, and digital positioning operation can be easily realized by open loop control. For this reason, it is widely used in information home appliances such as cameras and optical disk devices, and office automation equipment such as printers and projectors.

  However, there was a problem that the motor stepped out when there was a lot of load on the motor or when high-speed rotation was attempted.

  In order to solve this problem, a method of preventing a step-out by attaching an encoder to a stepping motor and switching the energization in accordance with the position of the rotor, that is, a so-called brushless DC motor is conventionally performed.

  When this brushless DC motor is operated, there is a problem that the attachment position of the encoder is physically deviated from the design value. Even if the same control is performed due to the deviation from the design value, the speed, torque, and the like are different.

  For example, in Patent Document 1, in a brushless motor, the rotor of the motor is rotated from the outside with different power, and the physical position shift of the encoder is caused by the phase difference between the electromotive force signal generated in the coil of the brushless motor and the encoder output signal. A detection method has been proposed.

JP 2005-12955 A

  However, with the conventional technique disclosed in Patent Document 1, it becomes impossible to adjust the brushless motor after it is incorporated into a device intended for driving. This is because it is necessary to expose the rotor portion of the motor in order to connect to external power.

  Therefore, an object of the present invention is to provide a motor drive device that can specify the amount of positional deviation of the rotor position detection unit even after the motor is incorporated in the drive device.

In order to achieve the above object, a motor driving apparatus according to one aspect of the present invention includes a motor including a rotor magnet, a rotor position detection unit that detects the position of the rotor magnet, and an excitation signal to a coil of the motor. A control unit that performs open-loop driving for switching the motor at predetermined time intervals and feedback driving for switching the excitation signal to the coil of the motor based on the output signal of the rotor position detection unit, and switching of the excitation signal applied to the coil of the motor A time difference measuring unit that measures a time difference between the switching timing and the switching timing of the output signal of the rotor position detecting unit, and a driven member driven by the motor, and the driven member includes a cam and Driving force is transmitted by a cam follower that traces the cam, and the cam lift is substantially zero. A first region to be set and a second region to be set with a cam lift larger than the first region are formed, and the control unit drives the motor to the open loop, so that the motor is driven When the cam follower traces the first region of the cam, the control unit identifies the amount of positional deviation of the rotor position detection unit based on the output of the time difference measurement unit , The control unit corrects a delay phase angle when the motor is feedback-driven based on the positional deviation amount.

  ADVANTAGE OF THE INVENTION According to this invention, the motor drive device which makes it possible to specify the amount of positional deviation of a rotor position detection part even after incorporating a drive device into a motor can be provided.

1 is an external view of a stepping motor according to an embodiment of the present invention. It is sectional drawing which fractured | ruptured the stepping motor of FIG. 1 in the plane which passes along the magnetic sensitive pole of a magnetic sensor. It is a block diagram which shows the drive circuit of the stepping motor of FIG. It is a figure which shows the positional relationship of the drive pulse generation yoke in a present Example, and a sensor. It is a figure which shows the deviation | shift amount of the attachment position of the sensor in a present Example. It is a figure explaining the timing difference of the sensor output in this example, and a drive pulse output. 6 is a flowchart showing a flow of processing for specifying a positional deviation amount of the magnetic sensor 6; It is a figure which shows the external appearance of the lens barrel of the imaging device which is a drive object in a present Example. It is a figure explaining the structure of the lens barrel in a present Example. It is a figure which shows the delay amount of the load torque with respect to a motor, and a sensor output drive pulse output. It is a figure which shows the relationship of the TN curve corresponding to two types of drive pulse change timings of a present Example. It is a flowchart which shows the flow of a load amount specific process. It is a figure which shows the load measuring method of a lens-barrel. It is a schematic explanatory drawing of the feedback drive of a present Example.

  EMBODIMENT OF THE INVENTION Below, the form which implemented the motor drive device of this invention is described in detail based on an accompanying drawing.

  FIG. 1 is an external perspective view of a stepping motor according to the present invention.

  For the sake of explanation, some parts are shown broken away.

  In FIG. 1, a stepping motor 1 includes a rotor (output shaft) 3 having a magnet (rotor magnet) 2, a first coil 4a, a second coil 4b, a first yoke 5a, a second yoke 5b, and a first coil. The magnetic sensor (rotor position detector) 6 is provided.

  Among these, the first coil 4a, the second coil 4b, the first yoke 5a, the second yoke 5b, and the first magnetic sensor 6 constitute a stator.

  The magnet 2 is a permanent magnet on a cylinder whose outer periphery is multipolar excited to n poles. It has a pattern in which the strength of the magnetic force in the radial direction changes sinusoidally with respect to the angular position. In this embodiment, n = 8 poles are magnetized.

  The rotor 3 is rotatably supported with respect to the stator, and is fixed integrally with the magnet 2.

  The coil 4a and the coil 4b are each formed by winding a large number of conductive wires, and are wound around a bobbin around the rotor rotation center axis.

  The yoke 5a and the yoke 5b each have a plurality of magnetic pole teeth that are excited by the coils 4a and 4b. By switching the excited pole, the torque applied to the rotor 3 can be changed.

  The magnetic sensor 6 is a non-contact type magnetic detecting means for detecting the magnetic flux of the magnet 2 such as a Hall element. One sensor includes the first sensitive magnetic pole 6a and the second sensitive magnetic pole 6b. The first and second magnetic sensitive poles 6 a and 6 b sense a magnetic field change accompanying the rotation of the magnet 2.

  The magnetic sensor 6 has two output terminals and outputs a voltage according to the magnetic flux density penetrating each of the magnetic sensitive poles. If the magnetic flux density passes through the magnetic pole and the magnetic pole density is N pole, a positive voltage output is output. In the present embodiment, the output of the magnetic sensor 6 is a binarized output, a high signal is output in the case of the N pole, and a low signal is output in the case of the S pole. Take control. However, the magnetic sensor 6 may be an analog output sensor that outputs a magnetic force in a sine wave form and controls the motor by analog control based on the signal.

  FIG. 2 is a cross-sectional view of the stepping motor of FIG. 1 taken along a plane perpendicular to the central axis of the rotor and passing through the magnetic pole of the magnetic sensor.

  For simplification of the drawing, only the positional relationship of the magnet 2, the rotor 3, and the magnetic sensor 6 is shown. The magnetically sensitive magnetic poles 6a and 6b in the magnetic sensor are at a certain distance away from each other in the sensor package, and are located at a certain angle α when placed in the motor.

FIG. 3 is a block diagram showing the internal configuration of the motor and the control unit. High and low sensor rectangular waves are output from the first and second sensitive magnetic poles 6a and 6b of the magnetic sensor 6 in the stepping motor 1 depending on the state of the magnet immediately below. The sensor rectangular wave enters the control unit 7 and enters the encoder unit 701, the cycle count unit 702, and the drive pulse control unit 703, respectively. The drive pulse control unit 703 can perform open loop driving for switching excitation signals to be applied to the coils at predetermined time intervals and feedback driving to switch excitation signals to be applied to the coils based on the output signal of the magnetic sensor 6. The encoder unit 701 receives the output signals of the magnetic sensors 6 a and 6 b and outputs the encoder position to the drive pulse control unit 703. The period counting unit 702 counts the period when the outputs of the magnetic sensors 6a and 6b are switched. The drive pulse control unit 703 includes a signal time difference calculation unit 703a and a correction unit 703b. The signal time difference calculation unit 703a uses the sensor rectangular wave, the encoder position of the encoder unit 701, and the cycle count value of the cycle count unit 702 to determine the switching timing of the excitation signal applied to the coil and the signal switching timing of the magnetic sensor 6. Calculate the time difference. That is, the signal time difference calculation unit 703a functions as a time difference measurement unit. Then, the drive pulse control unit 703 specifies the positional deviation amount of the magnetic sensor 6 based on the calculated value of the signal time difference calculation unit 703a and the design value of the calculation result stored in the storage unit 705. Correcting unit 703b is that to calculate the correction value for correcting the positional deviation of the magnetic sensor 6 identified. In the bridge circuit 8, the coils 4 a and 4 b are excited in accordance with the excitation signal from the drive pulse control unit 703. In this embodiment, the period time obtained from the period count unit 702 is regarded as an electrical phase corresponding to 360 °. The drive pulse control unit 703 performs a brushless rotation operation by sending an excitation signal to the bridge circuit 8 when a time corresponding to a preset phase difference has elapsed with respect to the current cycle time. Since there is no risk of step-out when used in a low speed region, the drive pulse control unit 703 drives the bridge circuit 8 from the drive pulse control unit 703 by open control without using the sensor output of the magnetic sensor 6. A stepping rotation operation in which a pulse is sent for rotation can also be performed.

  Next, how the stepping motor 1 is driven by the sensor binarized output signal will be described with reference to FIGS.

  FIG. 4 is a diagram showing the arrangement of one magnetic pole tooth of each of the first and second magnetic sensitive poles 6a and 6b and the first and second yokes 5a and 5b of the magnetic sensor 6 in the stepping motor 1 in this embodiment. It is. The first and second magnetic sensitive poles 6a and 6b of the magnetic sensor 6 are disposed at positions separated by 22.5 ° in physical angle. The magnetic pole teeth of the second yoke 5b are present at a position 67.5 ° away from the first magnetic sensitive pole 6a, and the first yoke 5a is located at a position 22.5 ° away from the magnetic pole teeth of the second yoke 5b. There are magnetic pole teeth. 22.5 ° corresponds to 90 ° when converted to an electrical angle where one wavelength of the sensor output is 360 °. There are four magnetic pole teeth of the first and second yokes 5a and 5b every 90 ° in physical angle (every 360 ° in electrical angle).

  FIG. 5 illustrates the amount of displacement of the mounting position of the magnetic sensor 6 in the stepping motor 1 in this embodiment. The position of the magnetic sensor 6 in FIG. The direction written as CW in FIG. 5 is defined as the normal rotation direction of the motor rotation in this embodiment. FIG. 5B shows a state in which the magnetic sensor 6 is disposed at a position shifted in the CW direction by a positional shift amount β at a physical angle with respect to the position of the magnetic sensor 6 in FIG. On the other hand, FIG. 5C shows a state in which the magnetic sensor 6 is disposed at a position shifted by a physical shift angle γ with respect to the position of the magnetic sensor 6 in FIG. Show.

  FIG. 6 shows the drive pulses applied to the first and second yokes 5a and 5b as A-phase pulses and B-phase pulses, respectively, and the output voltages of the first and second magnetic poles 6a and 6b of the magnetic sensor are shown as sensors. The time relationship is shown as a and sensor b.

  Consider a case where the stepping motor 1 is driven in an open loop, that is, the A-phase pulse signal is rotated without using the output of the sensor a and the B-phase pulse signal is rotated without using the output of the sensor b. In this case, an output at a timing at which the position of the rotor corresponding to the load at the time of rotation is reflected is output from the magnetic sensor 6 and detected as sensors a and b in FIG. By calculating the time difference t1, t2 between the output change timing of the sensors a and b and the output change timing of the drive pulse, it is possible to obtain information on the motor drive state.

  Further, consider a case where the stepping motor 1 is feedback driven based on the output of the magnetic sensor 6, that is, a brushless driving operation is performed. In this case, the cycle count unit 702 calculates sensor cycles represented by T1 and T2 in FIG. 6 from the switching timing of the outputs of the sensors a and b. Then, the drive pulse signal is changed with a certain delay time from the output timing of the magnetic sensor 6 according to a preset delay phase angle.

  A specific example is shown in FIG. The switching time of the A-phase driving pulse is set from the switching timing of the output of the sensor a, and the switching time of the B-phase driving pulse is set from the switching timing of the output of the sensor b. As shown in FIG. 6, the second falling timing is detected from the output switching timing of the sensor a. At this time, the period T1 is determined by calculating the time difference from the first falling timing of the sensor a. Next, for the period T1, a time difference t1 is calculated according to a preset delay phase angle. A setting is made so that the A-phase drive pulse falls at the time when the time t1 has elapsed from the second fall timing of the sensor a. The same processing is performed for the sensor b and the B-phase drive pulse, and the amount of time t2 is calculated according to the period T2 and the preset delay phase angle.

  8 and 9 show an outline of the lens barrel unit of the image pickup apparatus that is a driving target of the stepping motor 1 in this embodiment.

  FIG. 8 is an external view of the lens barrel unit 8 as a driven member in the present embodiment. FIG. 8A shows a retracted state in which the lens barrel unit 8 is housed. FIG. 8B shows a state where the lens barrel is extended. The lens barrel unit 8 in the present embodiment has a three-stage configuration, and includes a three-stage cylinder of a cylinder member 801, a cylinder member 802, and a cylinder member 803 shown in FIG.

  FIG. 9 is a diagram illustrating the structure of the lens barrel unit 8. FIG. 9A is a development view of the cylindrical surface of the cylindrical member 801. A cam 902 is formed on the cylindrical surface 905 of the cylindrical member 801. A cam pin 901 formed on the cylindrical surface of the cylindrical member 803 is engaged with the cam 902. The cam pin 901 functions as a cam follower that traces the cam 902, and the driving force is transmitted by the cam pin 901 tracing the cam 902. FIG. 9B is a development view of the cylindrical surface 907 of the cylindrical member 802. A cam 906 is formed on the cylindrical surface of the cylindrical member 802. A cam pin 901 formed on the cylindrical surface of the cylindrical member 803 is engaged with the cam 906. FIG. 9C illustrates the cylindrical surface 905 of the cylindrical member 801, the cylindrical surface 907 of the cylindrical member 802, and the cam pin 901 of the cylindrical member 803.

  When the stepping motor 1 is driven in the state illustrated in FIG. 9C, the cylindrical member 802 is rotationally driven by the stepping motor 1, and the cylindrical surface 907 of the cylindrical member 802 is driven in the direction of the arrow 908. When the cylindrical member 802 is driven in the direction of the arrow 908, the edge of the cam 906 comes into contact with the cam pin 901, and the cylindrical member 802 is integrated with the cylindrical member 803 and is driven in the direction of the arrow 908. Since the cylindrical member 801 is not driven by the motor, the cylindrical surface 905 of the cylindrical member 801 is stationary with respect to the cylindrical surface 907 of the cylindrical member 802. Therefore, when the stepping motor 1 rotates the cylindrical member 802, the cam pin 901 of the cylindrical member 803 traces the cam 902 of the cylindrical member 801.

  The cam 902 of the cylindrical member 801 has a cam region 904 section (first region) where the cam lift in the optical axis direction 910 is set to substantially zero and a cam lift in the optical axis direction 910 larger than the cam region 904 section. An area (second area) of the cam area 903 to be formed is formed. In the section of the cam region 904, the cam lift in the optical axis direction 910 is set to substantially zero. Therefore, when the cam pin 901 of the cylindrical member 803 traces the section of the cam region 904 of the cam 902, the cylindrical member 803 moves in the optical axis direction 910. Not drawn out.

  When the cylindrical surface 907 of the cylindrical member 802 is further driven in the direction of the arrow 908 from here, the cam pin 901 of the cylindrical member 803 traces the cam 902 and moves in the direction of the arrow 909. In the section of the cam region 903, the cam lift in the optical axis direction 910 is set larger than the section of the cam region 904. Therefore, when the cam pin 901 of the cylindrical member 803 traces the section of the cam region 903 of the cam 902, the cylindrical member 803 It is drawn out in the optical axis direction 910. When the cam pin 901 of the cylindrical member 803 traces the section of the cam region 903, the cam 906 guides the movement of the cam pin 901 in the optical axis direction 910.

  When the cam pin 901 of the cylindrical member 803 traces the section of the cam region 903, the lens barrel unit 8 is changed from the retracted state illustrated in FIG. 8A to the extended state illustrated in FIG. 8B.

The driving load of the stepping motor 1 when the cam pin 901 of the cylindrical member 803 traces the section of the cam area 904 is larger than the driving load of the stepping motor 1 when the cam pin 901 of the cylindrical member 803 traces the section of the cam area 903. Get smaller.
(When the cam pin 901 traces the section of the cam area 904, the sensor position deviation amount is specified)
Hereinafter, with reference to the processing flow of the flowchart of FIG. 7, the description will be given of how to specify the displacement amount of the magnetic sensor 6 when the cam pin 901 of the cylindrical member 803 traces the section of the cam region 904 of the cam 902.

  Starting from step S701, the process first proceeds to the retracted end search in step S702. In step S702, one end of the target drive region driven by the stepping motor 1 is detected, and that end is set as the start position. One end desired to be detected in this embodiment is a state where the cam pin 901 of the cylindrical member 803 shown in FIG. 9 is positioned at the right end of the cam 902 of the cylindrical member 801.

  As a method for detecting this position, the stepping motor 1 is operated in the retracted direction, and the position where the stop is detected from the sensor output is used as the retracted end, or a detection mechanism such as a photocoupler is provided in the lens barrel. There is a method to make it possible to detect that the end has been reached.

  In step S702, a retracted end search is performed, and if it is detected that the lens barrel is at the retracted end, the stepping motor 1 is stopped and the process proceeds to step S703.

  In step S703, the drive pulse control unit 703 drives the stepping motor 1 with open loop control at a predetermined adjustment speed, and the cam pin 901 of the cylindrical member 803 is cam region of the cam 902 as shown in FIG. Trace 904 interval. While the cam pin 901 of the cylindrical member 803 traces the section of the cam region 904 of the cam 902, the signal time difference calculation unit 703a calculates the time differences t1 and t2 from the sensor output switching timing shown in FIG. taking measurement. Since this measurement has a higher accuracy when the number of samples is larger, the signal time difference calculation unit 703a takes samples of the time differences t1 and t2 as much as possible and outputs an average value. In the section of the cam region 904 of the cam 902, the cam lift in the optical axis direction 910 is set to substantially zero, so that the driving load of the stepping motor 1 is reduced. Therefore, since the load of the lens barrel unit 8 is not directly applied to the stepping motor 1, it is not necessary to be affected by the individual load difference of the lens barrel unit 8.

  In step S704, the drive pulse controller 703 compares tm1 and tm2, which are design values corresponding to the time differences t1 and t2, respectively, with the time differences t1 and t2 calculated by the signal time difference calculator 703a. That is, the drive pulse controller 703 specifies how much the time differences t1 and t2 calculated by the signal time difference calculator 703a deviate from the design values tm1 and tm2. As a result, the amount of positional deviation of the magnetic sensor 6 can be specified. In step S704, the correction unit 703b calculates a correction value for correcting the positional deviation amount of the specified magnetic sensor 6. In step S705, the correction value calculated by the correction unit 703b is stored in the storage unit 705.

The drive pulse control unit 703 corrects the delay phase difference when the stepping motor 1 is feedback-driven using the correction value stored in the storage unit 705. That is, when the driving pulse controller 703 feedback drives the stepping motor 1 will Rukoto positional deviation of the magnetic sensor 6 is corrected.

  The design values tm1 and tm2 used here are those calculated from the mechanical design values or the average values of a large number of samples of the target motor-embedded device and stored in the storage unit 705.

  The case of rotating in the CW direction in FIG. 5 corresponds to the movement when the A-phase driving pulse and the B-phase driving pulse in FIG. 6 are applied. When the magnetic sensor 6 is located at the position of FIG. 5A, the phase relationship of the sensor a, the sensor b, the A-phase drive pulse, and the B-phase drive pulse in FIG. The delay time until the pulse is assumed to be the design values tm1 and tm2.

  Under the above premise, when the magnetic sensor 6 is located at the position of FIG. 5B, a drive pulse having the same cycle as that of FIG. 6 is applied. Then, at this time, the delay time from the measured sensor to the drive pulse is shortened, and the following relational expression is established.

360 × (t1− tm1 ) / T1 = 4β
360 × (t2− tm2 ) / T2 = 4β
The time differences t1 and t2 are obtained by measurement. T <b> 1 and T <b> 2 are values equivalent to the period of the driving pulse given to the stepping motor 1 by the control unit 7. Therefore, the physical positional deviation amount β of the magnetic sensor 6 is obtained from the above relational expression, and by using this positional deviation amount β, the positional relationship between the rotor 3 and the yoke 5 can be accurately detected during rotation.

  Similarly, when the magnetic sensor 6 is located at the position of FIG. 5C, the following relational expression is established, and the position of the rotor 3 and the yoke 5 is determined by using the calculated physical displacement amount γ of the magnetic sensor 6. The relationship can be accurately detected during rotation.

360 × (t1- tm1) / T1 = -4γ
360 × (t2− tm2 ) / T2 = −4γ
In subsequent step S705, the drive pulse control unit 703 calculates a correction value for correcting the positional deviation amount of the magnetic sensor 6 specified in step S704.

  By the above processing, the displacement amount of the position encoder mounting position in the stepping motor provided with the position encoder can be specified even after the stepping motor is incorporated in the assembling apparatus having the driven part.

By using this amount of displacement of the attachment position, it is possible to suppress control variations when feedback driving using a position encoder is performed.
(When the cam pin 901 traces the section of the cam area 903, the load amount is specified)
Hereinafter, with reference to the processing flow of the flowchart of FIG. 12, the load amount specification and the calculation of the optimum phase delay angle when the cam pin 901 traces the section of the cam region 903 will be described.

  The process according to the flowchart of FIG. 12 starts from step S1201 and continues to step S1202. In step S1202, the positional deviation amount of the magnetic sensor 6 described above is specified. For simplicity of explanation, it is assumed that the amount of positional deviation in step S1202 is 0, that is, the result that the magnetic sensor 6 is positioned at the design value is obtained.

  Next, in step S1203, the drive pulse control unit 703 drives the stepping motor 1 by open loop control at a predetermined adjustment speed, and the cam pin 901 of the cylindrical member 803 moves the section of the cam region 903 of the cam 902. Trace. When the cam pin 901 traces the section of the cam region 903 of the cam 902, the signal time difference calculation unit 703a measures the time difference from the sensor output switching timing of the magnetic sensor 6 to the driving pulse switching timing. Do.

  When the cam pin 901 of the cylindrical member 803 traces the section of the cam region 903 of the cam 902, a load is applied to the stepping motor 1. In FIG. 13, the stepping motor 1 in which the displacement amount of the magnetic sensor 6 illustrated in FIG. 5A is 0 in step S1203 is incorporated in the lightly loaded lens barrel unit 8 and the heavily loaded lens barrel unit 8. This is an example. FIG. 13A corresponds to the case where the stepping motor 1 is incorporated in the lens barrel unit 8 with a light load. FIG. 13B corresponds to the case where the stepping motor 1 is incorporated in the heavy-duty lens barrel unit 8. When the stepping motor 1 is incorporated in the lens barrel unit 8 with a heavy load, a large load is applied to the rotor 3, so that the rotational position of the rotor 3 is changed after the driving pulse is switched as compared to when the load is light. The time until the output is switched becomes longer. Comparing (a) and (b) of FIG. 13, the switching timing of the sensor output from the switching of the drive pulse is delayed in time in FIG. 13 (b) than in FIG. 13 (a). I can see that.

  In FIG. 13B when the rotor is delayed, the delay time from the sensor a to the A-phase drive pulse is t5, and the delay time from the sensor b to the B-phase drive pulse is t6. Since the periods T1 and T2 in the figure are equal to the periods of the A-phase and B-phase drive pulses output from the control unit 7, the delay times t5 and t6 are treated the same as the delay phase by using this period information. be able to.

The delay time from the sensor a to the A-phase drive pulse in FIG. 13A where the rotor delay is smaller than that in FIG. 13B is t3, and the delay time from the sensor b to the B-phase drive pulse is t4. At this time,
t3> t5, t4> t6
The relationship holds.

  In step S1203, after the signal time difference calculation unit 703a measures the time difference from the sensor output switching timing to the driving pulse switching timing, the process proceeds to step S1204, and the driving pulse control unit 703 specifies the load amount of the lens barrel. I do.

In step S1204, the time difference measured by the signal time difference calculation unit 703a is corrected using the correction value stored in the storage unit 705. Thereby, the positional deviation amount of the magnetic sensor 6 included in the time difference measured by the signal time difference calculation unit 703a is corrected. Then, the lens barrel is compared by comparing the data obtained from the output of the signal time difference calculation unit 703a in which the positional deviation amount of the magnetic sensor 6 is corrected with the load amount specifying data stored in the storage unit 705 control unit. The load amount of the unit 8 is specified.

FIG. 10 shows the load amount specifying data stored in the storage unit 705 in advance. This is data in which the horizontal axis represents the time difference from the sensor output switching timing to the driving pulse switching timing when the open loop driving is performed at a constant speed, and the vertical axis represents the load applied to the stepping motor 1. . The load amount specifying data is compared with the data obtained from the output of the signal time difference calculation unit 703a in which the positional deviation amount of the magnetic sensor 6 is corrected. Thus, the drive pulse control unit 703 can specify the load applied to the stepping motor 1 when the cam pin 901 of the cylindrical member 803 traces the section of the cam region 903 of the cam 902, that is, the load amount of the lens barrel unit 8. Here, the time difference obtained in FIG. 13B is 1001, and the time difference obtained in FIG. Based on the data of the load characteristic curve 1005, the load in the case of FIG. 13B is identified as L1, and the load in the case of FIG. 13A is identified as L2.

  In the subsequent step S1205, a delay phase angle for calculating an appropriate pulse delay time is calculated according to the load when the stepping motor 1 is feedback-driven, and stored in the storage unit 705.

  Here, the outline of the operation at the time of feedback driving will be described in advance with reference to FIG. In the drive in FIG. 14, the A-phase drive pulse and the B-phase drive pulse change based on the output switching time and the cycle time of the sensor a and the sensor b, respectively. The second falling timing of the sensor a in FIG. 14 is detected. At this time, the period T1 is determined by calculating the time difference from the first falling timing of the sensor a. Next, the calculation result of T1 × (θ / 360) is set as the delay time from the delay phase angle θ set in advance for the period T1. Then, the setting is made so that the A-phase drive pulse falls when this delay time elapses from the second fall timing of the sensor a. Similar processing is performed for the sensor b and the B-phase drive pulse, and the delay time amount until switching of the B-phase pulse is calculated according to the period T2 and the preset delay phase angle θ.

  In feedback driving in which the excitation signal is switched based on the output of the magnetic sensor 6 for driving, the torque-rotation speed characteristic (TN curve characteristic) of the stepping motor 1 changes according to the delay phase angle θ. The conceptual diagram is shown in FIG.

  Even if the same stepping motor 1 is used in FIG. 11, different TN curve characteristics are obtained by changing the delay phase angle θ to θ1 and θ2 when performing feedback driving. In the present embodiment, either one of the values of the delay phase angles θ1 and θ2 is selected and used in feedback driving. At this time, it is considered to rotate at a rotational speed exceeding the target rotational speed shown in the figure. When the load of the lens barrel unit 8 is L2, both the delay phase angles θ1 and θ2 have characteristics exceeding the target rotational speed. Therefore, in this case, since the delay phase angle θ1 has better characteristics than the delay phase angle θ2, the delay phase angle θ1 is set. On the other hand, when the load of the lens barrel unit 8 is L1, the target rotational speed cannot be reached in the case of the delay phase angle θ1. In this case, since the target rotational speed can be exceeded if the delay phase angle θ2, the delay phase angle θ2 is set. That is, in the case of the measurement result of FIG. 13A, the delay phase angle θ1 is set, and in the case of the measurement result of FIG. 13B, this corresponds to setting the delay phase angle θ2.

  In step S1205, the calculated delay phase angle is stored in the storage unit 705 and used as an optimum value when the stepping motor 1 is feedback driven.

  When the drive pulse control unit 703 drives the stepping motor 1 by feedback control, and the cam pin 901 of the cylindrical member 803 traces the section of the cam region 903 of the cam 902, it is stored in the storage unit 705 in step S1205. Using the delayed phase angle. As a result, the drive pulse control unit 703 drives the stepping motor 1 in the feedback manner, so that when the cam pin 901 traces the section of the cam region 903 of the cam 902, the load amount on the stepping motor 1 is corrected. Become.

  Finally, the adjustment process ends in step S1206.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

  In this embodiment, the built-in driving target of the stepping motor 1 is the lens barrel of the image pickup apparatus. However, the same can be applied to the case where the stepping motor 1 is incorporated for driving an aperture unit of the image pickup apparatus, for example. . In this case, a drive region with a light load relative to the motor corresponds to a drive region with a small overlap of aperture blades, and a drive region with a heavy load corresponds to a drive region with a large overlap of aperture blades.

  In this embodiment, the magnetic sensor 6 is positioned at the design position in step S1201 in the flowchart of FIG. However, even if the position deviates to a place other than the design value here, the optimal control can be performed by adding the positional deviation amount obtained in step S1201 to the final result of the present embodiment.

  Further, in this embodiment, the delay phase angle θ is set so as to obtain a speed equal to or higher than the target speed in FIG. 11, but control may be performed to reach the target speed by changing the voltage value during this driving.

  In this embodiment, the delay phase angle can be selected from only two. However, the delay phase angle can be selected from three or more delay phase angles, or an appropriate delay phase angle can be set steplessly from the measurement result. May be.

DESCRIPTION OF SYMBOLS 1 Stepping motor 2 Magnet 3 Rotor 6 Magnetic sensor 7 Control part 701 Encoder part 702 Period count part 703 Drive pulse control part 703a Signal time difference calculation part 703b Correction part

Claims (5)

A motor with a rotor magnet;
A rotor position detector for detecting the position of the rotor magnet;
A control unit that performs open loop driving for switching an excitation signal to the motor coil at predetermined time intervals and feedback driving for switching the excitation signal to the motor coil based on an output signal of the rotor position detection unit;
A time difference measuring unit that measures a time difference between a switching timing of an excitation signal applied to the coil of the motor and a switching timing of an output signal of the rotor position detection unit;
A driven member driven by the motor,
The driven force is transmitted to the driven member by a cam and a cam follower that traces the cam.
The cam is formed with a first region in which a cam lift is set to substantially zero and a second region in which a cam lift larger than the first region is set,
When the control unit drives the motor in the open loop, the motor drives the driven member, and the cam follower traces the first region of the cam. Based on the above, the control unit specifies the amount of positional deviation of the rotor position detection unit ,
Before SL controller motor driving device and corrects the delay phase angle when the motor is the feedback driven based on the positional deviation amount. A storage unit for storing a time difference between a switching timing of the excitation signal applied to the motor coil and a switching timing of the output signal of the rotor position detection unit when the displacement amount of the rotor position detection unit is zero; And
The control unit identifies a displacement amount of the rotor position detection unit by comparing a time difference stored in the storage unit and a time difference measured by the time difference measurement unit. The motor drive device described. When the control unit drives the motor in the open loop, the motor drives the driven member, and the cam follower traces the second region of the cam. Based on the amount of load on the motor,
When the control unit drives the motor to feedback the motor, the motor drives the driven member, and the cam follower traces the second region of the cam. The motor driving apparatus according to claim 1, wherein the load amount is corrected.   4. The motor driving apparatus according to claim 1, wherein the driven member is a cylinder member included in a lens barrel of the imaging apparatus. 5. A motor with a rotor magnet;
A rotor position detector for detecting the position of the rotor magnet;
A control unit that performs open loop driving for switching an excitation signal to the motor coil at predetermined time intervals and feedback driving for switching the excitation signal to the motor coil based on an output signal of the rotor position detection unit;
A time difference measuring unit that measures a time difference between a switching timing of an excitation signal applied to the coil of the motor and a switching timing of an output signal of the rotor position detection unit;
A driven member driven by the motor,
The driven force is transmitted to the driven member by a cam and a cam follower that traces the cam.
The method of controlling a motor driving device, wherein the cam is formed with a first region where a cam lift is set to substantially zero and a second region where a cam lift larger than the first region is set,
When the control unit drives the motor in the open loop, the motor drives the driven member, and the cam follower traces the first region of the cam. Based on the above, the control unit specifies the amount of positional deviation of the rotor position detection unit ,
Control method of the preceding Symbol controller motor driving device and corrects the delay phase angle when the motor is the feedback driven based on the positional deviation amount.