Control device, imaging device, and control method

Abstract

To provide a control device capable of executing excellent angle advance control.SOLUTION: A control device includes: a generation unit configured to generate target position information on a motor; an acquisition unit configured to acquire rotation position information on the motor; a drive control unit configured to generate a drive signal of the motor according to an amount of deviation between the target position information and the rotation position information; and a setting unit configured to set a coordinate origin of the rotation position information according to difference between a center value of a fluctuation amount of the rotation position information and the fluctuation amount of the rotation position information.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device for a stepping motor using an encoder, an imaging device, and a control method. [Background technology]

[0002] Conventionally, a method has been proposed for controlling the lead angle of a drive waveform relative to the rotation phase of a motor obtained from a sensor in order to maximize the rotation efficiency of the motor and to achieve high speed and power saving. Patent Document 1 discloses a method for controlling the lead angle of a drive waveform by inversely converting a drive counter generated by adding a target lead angle determined based on the deviation between position information and a target position of control to rotation position information of the motor into a waveform signal. Patent Document 2 discloses a configuration for calculating a second drive amount according to the proportion of a step phase included when a step phase of a predetermined phase region is included when microstep driving is performed with a first drive amount. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-083196 [Patent Document 2] Patent No. 6168841 Summary of the Invention [Problem to be solved by the invention]

[0004] Fluctuations may occur in the motor's rotational position information due to the motor's cogging or the detection accuracy of the rotational phase. In this case, in the configuration of Patent Document 1, coordinate shifts occur in the motor's rotational position information, and the lead angle cannot be set correctly. In addition, in the configuration of Patent Document 2, an attempt is made to suppress the variation in the amount of rotation caused by cogging by adjusting the microstep driving amount according to the motor's rotational position information, but it is not possible to suppress the occurrence of coordinate shifts in the rotational position information.

[0005] An object of the present invention is to provide a control device capable of performing good advance angle control. [Means for solving the problem]

[0006] A control device as one aspect of the present invention is characterized in having a generation unit that generates target position information for a motor, an acquisition unit that acquires rotational position information for the motor, a drive control unit that generates a drive signal for the motor in accordance with the amount of deviation between the target position information and the rotational position information, and a setting unit that sets the coordinate origin of the rotational position information in accordance with the difference between the center value of the fluctuation amount of the rotational position information and the fluctuation amount of the rotational position information. Effect of the Invention

[0007] According to the present invention, it is possible to provide a control device capable of performing good advance angle control. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is an explanatory diagram of a motor unit according to the embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram of a motor unit including an electric circuit for driving the motor unit. [Diagram 3] FIG. 4 is a diagram illustrating the process of an encoding processing unit. [Figure 4] FIG. 4 is a diagram showing the relationship between the advance angle and the motor rotation speed. [Diagram 5] 13 is a flowchart showing the process of an advance angle / power rate control unit. [Figure 6] 13 is a flowchart showing a target advance angle / power rate selection process. [Figure 7] 13 is a flowchart showing a speed control process. [Figure 8] FIG. 11 is a diagram illustrating an advance angle control process. [Figure 9] 11A and 11B are diagrams illustrating the relationship between the variation in the coordinate origin setting timing and the phase variation of the coordinate origin. [Figure 10] 5 is a diagram showing the relationship between a position detection counter and a target position counter. FIG. [Figure 11] 13 is a flowchart showing a coordinate origin setting process. [Figure 12] 13 is a diagram showing the relationship between the timing and count value when the coordinate origin is set. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to refer to the same components, and duplicated descriptions will be omitted.

[0010] Fig. 1(a) is a diagram showing a schematic configuration of a motor unit according to an embodiment of the present invention. A rotating shaft 102 of a stepping motor (hereinafter, motor) 101 is a lead screw, and is engaged with a rack 103. A lens (moving member) 104, which is a driven member, is connected to the rack 103, and moves in the axial direction in response to the rotation of the rotating shaft 102. Note that, in this embodiment, the lens 104 will be used as an example of a moving member, but the present invention is not limited thereto.

[0011] The reference position of the lens 104 is determined by a PI (photo interrupter) 105 arranged on a fixed member (not shown) and a light shielding plate 106 provided on the lens 104. The PI 105 is composed of a light emitting section and a light receiving section, and when the light shielding plate 106 enters between the light emitting section and the light receiving section as the lens 104 moves, the detection signal of the PI 105 switches from High to Low. This switching position is set as the reference position. In this embodiment, the PI 105 and the light shielding plate 106 form a position detection section.

[0012] A rotation phase detection magnet 107 is attached to the rotating shaft 102, and detects the rotation phase (rotation position) of the motor 101 in combination with a pair of Hall sensors (Hall-Ch0) 108 and (Hall-Ch1) 109 that serve as detectors.

[0013] FIG. 1(b) is a diagram for explaining the arrangement of the rotation phase detection magnet 107 and the Hall sensors 108, 109 when the motor 101 has 10 poles. The rotation phase detection magnet 107 is a cylindrical magnet with 10 poles corresponding to the number of motor poles. The poles are evenly arranged at a mechanical angle of 36°. The Hall sensors 108, 109 are arranged on an extension line of the rotation phase detection magnet 107 at a mechanical angle of 18°. With this configuration, two types of sine waves with a phase difference of 90° are detected from each Hall sensor according to the rotation of the motor 101.

[0014] 2 is a block diagram of a motor unit including an electric circuit for driving the motor unit according to the present embodiment. The motor unit includes amplifier circuits 201 and 202, a microcomputer (control device) 203, and a motor driver 210 in addition to the configuration shown in FIG.

[0015] The two-phase Hall signals detected by the Hall sensors 108 and 109 are amplified by the amplifier circuits 201 and 202. The amplified two-phase Hall signals are quantized by the AD converter 204, and the encoding processing unit (acquisition unit) 205 encodes the Hall signals to acquire a position detection counter (rotation position information) indicating the actual rotation position of the motor 101. The target position setting unit (setting unit) 206 generates a target position counter (target position information) for controlling the lens 104 at a target speed and target position. The same coordinate origin (origin information) is set for the position detection counter and the target position counter by the coordinate origin setting unit (setting unit) 207, and the coordinates are aligned. The lead angle / power rate control unit 208 sets a target lead angle, generates a drive counter by adding the target lead angle to the position detection counter, and sets a power rate. As a result, feedback control of the lead angle and amplitude of the drive waveform is performed so that the lens 104 moves following the target position counter. The power rate adjusts the amplitude of the drive waveform, for example, a power rate of 60% adjusts the amplitude of the drive waveform to 60%. The drive waveform generation unit 209 performs SIN / COS conversion on the drive counter and generates a two-phase drive waveform (drive signal) whose amplitude is adjusted according to the power rate. In this embodiment, the lead angle / power rate control unit 208 and the drive waveform generation unit 209 constitute the drive control unit.

[0016] However, since feedback control is not possible during the initialization drive until the coordinate origin is set by the coordinate origin setting unit 207, open control is performed during this period. In this case, the lead angle / power rate control unit 208 sets the target position counter obtained from the target position setting unit 206 as the drive counter, and also sets a power rate for open control to control the drive waveform.

[0017] The generated drive waveform is converted into a motor drive signal by the motor driver 210 and supplied to the motor 101. Note that the drive waveform is generally converted into a PWM signal and supplied to the motor driver 210, but it may be supplied after AD conversion processing, or may be supplied as drive waveform information from a communication port. (Hall waveform encoding) Fig. 3 is a diagram showing the processing of the encoding processing unit 205. Here, in accordance with the configuration of Fig. 1(b), the motor 101 has 10 poles, and accordingly, the rotation phase detection magnet 107 also has 10 poles.

[0018] 1A shows the magnet 107 for detecting the rotation phase of the motor 101. 1B and 1C show the waveforms of the Hall signals obtained at each rotation phase. Two types of Hall signals are obtained with a phase difference of 90°. Since the Hall signals are two-phase sine waves with a phase difference of 90°, the two types of signals have a sine and cosine relationship. The encoding processing unit 205 performs an arctangent calculation (tan -1(sin / cos)) to calculate phase information from 0° to 360°. (d) shows the calculated phase information. The calculated phase information is integrated to calculate rotation amount information of the motor 101. Multiplying the rotation amount information by the thread pitch of the lead screw can convert it to position information of the lens 104. Therefore, the rotation amount information of the motor 101 calculated by the encoding processing unit 205 is handled as a position detection counter for the lens 104 as shown in (e). Note that, although the phase information is information from 0° to 360° in this embodiment, it is determined by the resolution of the position detection counter, and the present invention is not limited to this.

[0019] The process of the coordinate origin setting unit 207 will be described below. When the microcomputer 203 is powered on, it executes a setting sequence for the coordinate origin of the lens 104. Specifically, it moves the lens 104 and searches for the lens position where the detection signal of the PI 105 switches from High to Low. When it acquires a reference signal indicating the switching position, the coordinate origin setting unit 207 initializes a position detection counter and a target position counter to predetermined values, with the searched switching position as the coordinate origin. This makes it possible to align (match) the coordinate origins of both, that is, the coordinates, and control the lens position. Note that the match includes not only the case where they match exactly, but also the case where they match substantially (approximately match). (Calculation of lead angle and power rate) FIG. 4 is a diagram showing the relationship between the lead angle and the rotation speed of motor 101, taking power rates of 50% and 60% as examples. In region (a), the rotation speed of motor 101 increases in proportion to the increase in lead angle. If the lead angle is further increased, region (b) is reached where the increase in rotation speed of motor 101 relative to the lead angle gradually becomes saturated. If the lead angle is further increased, region (c) is entered where the rotation speed of motor 101 drops from saturation point A. Furthermore, the higher the power rate, the greater the slope of the rotation speed of motor 101 relative to the lead angle in region (a), and saturation point A shifts to the side where the lead angle is larger. The relationship between the lead angle and the rotation speed is proportional within the range of region (a). In other words, the relationship between the lead angle and the rotation speed is expressed by the following equation (1).

[0020] Rotation speed = advance angle × γ + β (1) where γ is the slope and β is the offset.

[0021] In this embodiment, the relationship between the lead angle and the rotation speed is measured in advance, and the slope γ, offset β, and effective area W of formula (1) corresponding to region (a) of formula (1) are stored as a lead angle-rotation speed table based on the measurement data. Note that multiple lead angle-rotation speed tables are stored for each power rate, and can be selected according to the target speed. In this case, the smaller power rate is selected with priority.

[0022] Fig. 5 is a flowchart showing the processing of lead angle / power rate control unit 208. As described above with reference to Fig. 2, the same coordinate origin is set for the position detection counter and the target position counter by coordinate origin setting unit 207, and the coordinates are aligned. However, feedback control is not possible until the coordinate origin is set by coordinate origin setting unit 207, and open control is performed during this period. Therefore, lead angle / power rate control unit 208 switches its control method to open control during initialization driving and to feedback control when initialization driving is completed.

[0023] In step S500, the lead-angle / power rate control unit 208 determines whether the initialization driving is completed. If the lead-angle / power rate control unit 208 determines that the initialization driving is completed, it executes the process of step S510, and if it determines that the initialization driving is not completed, it executes the process of step S501.

[0024] In step S501, the advance angle / power rate control section 208 selects open control.

[0025] In step S502, the lead angle / power rate control unit 208 sets a target position counter as a drive counter.

[0026] In step S503, the lead-angle / power rate control unit 208 determines whether or not completion of setting of the coordinate origin in the coordinate origin setting unit 207 has been notified. If the lead-angle / power rate control unit 208 determines that completion of setting of the coordinate origin has been notified, it executes the process of step S504. If the lead-angle / power rate control unit 208 determines that completion of setting of the coordinate origin has not been notified, it executes the process of step S502.

[0027] In step S504, the advance angle / power rate control unit 208 selects feedback control.

[0028] In step S510, the advance angle / power rate control unit 208 executes a target advance angle / power rate selection process.

[0029] In step S511, the advance angle / power rate control unit 208 executes a speed control process.

[0030] FIG. 6 is a flowchart showing the target advance angle / power rate selection process.

[0031] In step S600, the lead angle / power rate control unit 208 determines whether the target speed has been updated. If the lead angle / power rate control unit 208 determines that the target speed has been updated, it executes the process of step S601, and if it determines that the target speed has not been updated, it ends this flow.

[0032] In step S601, the advance angle / power rate control unit 208 selects the minimum power rate.

[0033] In step S602, the lead angle / power rate control unit 208 refers to the lead angle-speed table corresponding to the selected power rate and the target speed, and calculates the target lead angle using equation (1).

[0034] In step S603, the lead-angle / power rate control unit 208 determines whether the calculated target lead-angle is within the range of the effective area W. If the lead-angle / power rate control unit 208 determines that the calculated target lead-angle is within the range of the effective area W, it ends this flow, and if it determines that the calculated target lead-angle is outside the range of the effective area W, it executes the processing of step S604.

[0035] In step S604, the advance angle / power rate control unit 208 selects a power rate that is one step higher.

[0036] The target speed is calculated from the amount of deviation (l) between the current position and the target position and the target time (t) required to move to the target position using the following formula (2).

[0037] Target speed = deviation (l) / target time (t) (2) 7 is a flowchart showing the speed control process. In this flow, feedback control of the lead angle and power rate of the drive waveform is performed using the target lead angle and power rate selected in the target lead angle / power rate selection process.

[0038] In step S700, the lead angle / power rate control unit 208 generates a drive counter by adding the target lead angle to the position detection counter.

[0039] In step S701, the lead angle / power rate control unit 208 calculates a target speed and an actual speed from the slope of the target position counter and the slope of the position detection counter.

[0040] In step S702, the lead angle / power rate control unit 208 determines whether the speed difference between the target speed and the actual speed is smaller than a predetermined amount. If the lead angle / power rate control unit 208 determines that the speed difference between the target speed and the actual speed is smaller than the predetermined amount, it ends this flow, and if it determines that the speed difference is larger than the predetermined amount, it executes the process of step S703. Note that if the speed difference between the target speed and the actual speed is equal to the predetermined amount, it is possible to arbitrarily set which step to proceed to.

[0041] In step S703, the lead angle / power rate control unit 208 calculates the amount of correction of the lead angle. The amount of correction of the lead angle is calculated using equation (3) from the relational expression between the lead angle and the speed in equation (1).

[0042] Advance angle correction amount = Speed ​​deviation amount / Gradient γ (3) However, the amount of advance of the advance angle needs to be limited within the range of region (a).

[0043] In step S704, the lead-angle / power rate control unit 208 determines whether the corrected lead-angle amount is within the range of the effective area W. If the lead-angle / power rate control unit 208 determines that the corrected lead-angle amount is within the range of the effective area W, it executes the process of step S705, and if it determines that the corrected lead-angle amount is outside the range of the effective area W, it executes the process of step S707.

[0044] In step S705, the advance angle / power rate control unit 208 corrects the target advance angle.

[0045] In step S706, the lead angle / power rate control unit 208 regenerates the drive counter in accordance with the correction of the target lead angle.

[0046] In step S707, the advance angle / power rate control unit 208 calculates the amount of correction of the power rate by multiplying the speed deviation amount by predetermined proportional, integral, and derivative gains.

[0047] In step S708, the advance angle / power rate control unit 208 corrects the power rate with the calculated power rate correction amount, which is calculated by multiplying the speed deviation amount by predetermined proportional, integral, and derivative gains.

[0048] By the above processing, it is possible to realize speed feedback for following up the target position counter by controlling the target advance angle and power rate. (Generation of driving waveforms) Fig. 8 is a diagram showing the process of lead angle control. Signals (a) to (c) and (e) are the same as those described with the same reference numerals in Fig. 3, and their description will be omitted here. (f) indicates a target position counter. As described above, the target lead angle and power rate are calculated so that the position detection counter (e) tracks the target position counter (f). In the following explanation, an example where the target lead angle is 90° will be explained.

[0049] The lead angle / power rate control unit 208 generates a drive counter (g) which is angle information by superimposing a target lead angle on a position detection counter (e). The position detection counter is a counter which integrates phase information from 0° to 360°, and similarly, the lower range of the drive counter from 0° to 360° becomes phase information.

[0050] Therefore, the drive waveform generating unit 209 performs SIN conversion and COS conversion on the drive counter to generate a two-phase drive waveform (SIN wave (h) and COS wave (i)) that is out of phase with respect to the rotation phase of the motor 101 by an advance angle. In addition, the power rate of the drive waveform is set so as to achieve a target amplitude, and the drive waveform is output to the motor driver 210. Note that, although the phase information has been described as information ranging from 0° to 360° in this embodiment, it is determined by the resolution of the position detection counter (e), and the present invention is not limited to this. (Cogging effect) A phenomenon (cogging) occurs in which the magnetic attraction force pulsates due to a bias in the magnetic flux distribution of the permanent magnet that is the rotor of the motor 101.

[0051] FIG. 9 is a diagram showing the relationship between the variation in the coordinate origin setting timing and the phase variation of the coordinate origin. (a) to (c) and (e) are the same as the signals described with the same reference numerals in FIG. 3, and the description will be omitted here. (i) shows the detection signal of the PI 105. The point at which the detection signal switches from High to Low is the reference position of the lens 104. In FIG. 9, the position detection counter (e) periodically fluctuates due to rotation unevenness caused by cogging. The fluctuation of the position detection counter (e) due to cogging occurs in synchronization with the rotation phase of the motor 101. That is, it occurs in synchronization with the detection waveforms of the Hall sensors 108 and 109 indicating the rotation phase of the motor 101. As described above, the PI 105 detects the reference position, and the same coordinate origin is set in the position detection counter and the target position counter at the timing of detecting the reference position, and the coordinates are aligned. However, the rotation phase of the motor 101 when the PI 105 detects the reference position and sets the coordinate origin varies due to the following factors (1) to (4) shown in FIG. (1) Variation in detection timing due to the distance between the PI 105 and the motor 101 (2) A delay of a maximum processing cycle from when the reference position is detected until the coordinate origin setting unit 207 sets the coordinate origin (variation in processing timing) (3) The total timing variation due to factors (1) and (2) (4) Fluctuation width of the position detection counter (e) during the period in which the reference position is detected and the coordinate origin is set FIG. 10 is a diagram showing the relationship between the position detection counter (e) and the target position counter (f) when the coordinate origin is set and when the motor is driven after the origin is set.

[0052] Fig. 10(a) shows a case where the coordinate origin is set at timing t1 when the position detection counter (e) is at the center (e') of the fluctuation. When the coordinate origin is set at the timing of Fig. 10(a), the target position counter (f) and the position detection counter (e) after the coordinate origin is set move in agreement with the fluctuation center (center value of the fluctuation amount) (e').

[0053] Fig. 10(b) shows a case where the coordinate origin is set at a timing where the position detection counter (e) is shifted from the center (e') of the fluctuation. If the coordinate origin is set at the timing of Fig. 10(b), the position detection counter (e) after the coordinate origin is set will be shifted from the center (e') of the fluctuation by an offset w2. In this case, the position detection counter (e) will be set to a coordinate that is shifted by the offset w2.

[0054] Fig. 10(c) shows a case where the coordinate origin is set at a timing where the position detection counter (e) is shifted from the center (e') of the fluctuation. If the coordinate origin is set at the timing of Fig. 10(c), the position detection counter (e) after the coordinate origin is set will be shifted by an offset w3 from the center (e') of the fluctuation. In this case, the position detection counter (e) will be set to a coordinate that is shifted by the offset w3.

[0055] As described above, the coordinates of the position detection counter (e) are shifted depending on the timing of setting the coordinate origin. In other words, the coordinates are shifted from the rotation position of the motor 101 and the target position.

[0056] The target speed in the lead angle control is calculated using equation (2) from the current position indicated by the position detection counter (e) and the target position indicated by the target position counter (f). The target lead angle is set using equation (1), and lead angle control is performed based on the set target lead angle. For this reason, if there is a deviation in the coordinate origin setting, the target lead angle cannot be set correctly. Also, since the drive counter is generated by superimposing the target lead angle on the position counter (e), if there is a deviation between the position counter (e) and the rotational position of the motor 101, it will not be possible to drive the motor 101 with the correct lead angle amount. The above factors make it impossible to process lead angle control correctly.

[0057] A method for correcting the deviation of the coordinate origin of the position detection counter due to the above-mentioned cause will be described below. Note that in this embodiment, the fluctuation of the position detection counter due to cogging will be described as an example, but the fluctuation of the position detection counter is not limited to this. For example, the fluctuation of the position detection counter can also be caused by mechanical factors such as uneven magnetization of the rotation phase detection magnet 107, axial runout of the rotating shaft 102 on which the rotation phase detection magnet 107 is mounted, and deviation in the mounting positions of the Hall sensors 108 and 109. (How to correct the coordinate origin) FIG. 11 is a flowchart showing the coordinate origin setting process performed by the coordinate origin setting unit 207.

[0058] In step S1100, the coordinate origin setting unit 207 determines whether the coordinate origin setting process is complete. If the coordinate origin setting unit 207 determines that the coordinate origin setting process is complete, it ends this flow, and if it determines that the coordinate origin setting process is not complete, it executes the process of step S1101.

[0059] In step S1101, the coordinate origin setting unit 207 calculates fluctuation data from the difference between the position detection counter (e) and the target position counter (f).

[0060] In step S1102, the coordinate origin setting unit 207 peak-holds the maximum value (fluctuation Max) and the minimum value (fluctuation Min) of the fluctuation data. In this embodiment, the fluctuation data refers to the periodic fluctuation of the position detection counter (e), and by measuring the deviation between the position detection counter (e) and the target position counter (f), the inclination component of the position detection counter is removed, and only the fluctuation component can be extracted.

[0061] In step S1103, the coordinate origin setting unit 207 determines whether or not rotation of one wave or more has been detected. One wave of the phase detection counter (e) is one wave of the waveform detected by the Hall sensor as shown in Fig. 9, and is the repeating period of fluctuation of the phase detection counter (e) due to cogging. If the coordinate origin setting unit 207 determines that rotation of one wave or more has been detected, it executes the process of step S1105, and if it determines that rotation of one wave or more has not been detected, it executes the process of step S1104.

[0062] In step S1104, the coordinate origin setting unit 207 completes setting of the maximum and minimum values ​​of the fluctuation data (fluctuation Max / Min setting).

[0063] In step S1105, the coordinate origin setting unit 207 detects a reference position that is the coordinate origin. As described above, the reference position is a point at which the detection signal of the PI 105 switches from High to Low.

[0064] In step S1106, the coordinate origin setting unit 207 resets the target position counter to a preset coordinate origin.

[0065] In step S1107, the coordinate origin setting unit 207 backs up the position detection counter when the reference position is detected as reference position data, and completes the setting of the reference position.

[0066] In step S1108, the coordinate origin setting unit 207 determines whether or not the completion of the fluctuation Max / Min setting and the reference position setting has been detected. If the coordinate origin setting unit 207 determines that the completion of the fluctuation Max / Min setting and the reference position setting has been detected, it executes the process of step S1109, and if it determines that the completion of the fluctuation Max / Min setting and the reference position setting has not been detected, it executes the process of step S1101.

[0067] In step S1109, the coordinate origin setting unit 207 first calculates the fluctuation center of the phase detection counter (e), and then calculates fluctuation correction data from the difference between the detected fluctuation data and the fluctuation center. The fluctuation center is calculated by the following formula (4) as the intermediate value between fluctuation Max and fluctuation Min in one period of the periodic fluctuation of the position detection counter (e).

[0068] Fluctuation center = (fluctuation MAX and fluctuation MIN) / 2 (4) In step S1110, the coordinate origin setting unit 207 sets the difference between the position detection counter (e) and the reference position data as the overrun amount. This makes it possible to correct the amount of movement of the position detection counter (e) from the time the reference position is detected in step S1105 until the origin coordinate of the position detection counter (e) is set.

[0069] In step S1111, the coordinate origin setting unit 207 resets the position detection counter (e) at the coordinate origin corrected using the overrun amount set in step S1110 and the fluctuation correction data calculated in step S1109 using the following equation (5).

[0070] Coordinate origin after correction = Coordinate origin - Overrun amount + Correction data (5) By correcting the coordinate origin, the coordinate origin of the target position counter (f) is set so that the fluctuation center (e') becomes the preset coordinate origin.

[0071] In this embodiment, the fluctuation of the position detection counter caused by cogging has been described. However, as described above, the fluctuation of the position detection counter can also occur due to mechanical factors of the components that detect the rotation phase of the motor 101. In this case, the period of the fluctuation of the position detection counter is synchronized with the rotation period of the motor 101. At this time, the fluctuation center (e') becomes the fluctuation center of one rotation of the motor 101. Therefore, by detecting the period of one rotation of the motor 101 in step S1103 and measuring the position fluctuation MAX and fluctuation MIN, it is possible to avoid deviation of the origin coordinate of the position detection counter (e) caused by mechanical factors.

[0072] FIG. 12 is a diagram showing the relationship between the timing and count value when setting the coordinate origin of the target position counter (f) and the position detection counter (e).

[0073] FIG. 12(a) shows the setting of the coordinate origin of the target position counter (f) and the position detection counter (e) when the timing of detecting one wave or more in step S1103 coincides with the timing of detecting the reference position in step S1105. In this case, the reference position is determined at the timing t1 when the PI (m) that detects the reference position switches from High to Low, and the target position counter (f) is reset to the origin coordinate at the reference position. In addition, at the same timing, the fluctuation center (e') is calculated, and the fluctuation correction data (p) is calculated from the difference between the fluctuation data and the fluctuation center (e') (step S1107). At this time, the position detection counter (e) and the reference position data coincide with each other, so the overrun amount is 0 (step S1110). Therefore, the position detection counter is reset to the coordinate origin corrected by the fluctuation correction data (p) as the rewritten value (s) (S1111). As a result, the position detection counter (e) is reset so that the fluctuation center (e') becomes the preset coordinate origin.

[0074] FIG. 12(b) shows a flow of setting the coordinate origin of the position detection counter (e) in the case where the timing t1 at which the reference position is detected in step S1105 precedes the timing t2 at which one or more waves are detected in step S1103. In this case, the reference position data is determined at the timing t1 at which PI(m) switches from High to Low. The target position counter (f) is reset to the origin coordinates with the determined reference position data (step S1106). The coordinate origin of the position detection counter (e) is set (step S1111) at a timing t2 later than the timing t1, so that the position detection counter (e) at this time deviates from the reference position data, and an overrun amount (u) occurs (step S1110). In this case, the coordinate origin corrected with the calculated fluctuation correction data (p) is rewritten to the coordinate origin further corrected by the overrun amount (u) as the rewritten value (s) and the position detection counter is reset (step S1111). As a result, the origin coordinate of the position detection counter (e) is set so that the fluctuation center (e') becomes the preset coordinate origin.

[0075] 12(c) shows the flow of setting the coordinate origin of the position detection counter (e) in the case where the timing t2 at which one or more waves are detected in step S1101 precedes the timing t1 at which the reference position is detected in step S1105. In this case, the coordinate origin of the target position counter (f) and the position detection counter (e) is set (step S1111) at the timing t1 at which the reference position data is set, so that the overrun amount (u) at this time becomes 0 (step S1110). Therefore, at the timing t1, the coordinate origin corrected by the fluctuation correction data (p) is set as the rewritten value (s) and the position detection counter is reset (S1111). As a result, the origin coordinate of the position detection counter (e) is set so that the fluctuation center (e') becomes the preset coordinate origin.

[0076] As described above, according to the configuration of this embodiment, the fluctuation center (e') of the position detection counter (e) is corrected to the coordinate origin in any pattern. This makes it possible to avoid offset deviation of the position detection counter (e) with respect to the target position counter (f).

[0077] In this embodiment, the case where a lens is driven as a driven member has been described. In this case, the microcomputer 203, which is a control device, may be provided in an imaging device equipped with a lens. Also, the microcomputer 203 may be provided in an interchangeable lens in an imaging system with interchangeable lenses. An external device that is neither an interchangeable lens nor an imaging device may be provided with the microcomputer 203, and the external device may control the position of the lens. Also, the driven member is not limited to a lens. Any driven member that can be driven linearly can be driven in the same manner as the lens of this embodiment.

[0078] The disclosure of this embodiment includes the following configuration. (Configuration 1) A generating unit that generates target position information of a motor; an acquisition unit for acquiring rotational position information of the motor; a drive control unit that generates a drive signal for the motor in accordance with a deviation amount between the target position information and the rotational position information; a setting unit that sets a coordinate origin of the rotational position information according to a difference between a central value of a fluctuation amount of the rotational position information and the fluctuation amount of the rotational position information. (Configuration 2) The control device according to configuration 1, wherein the drive control unit generates the drive signal by using a target advance angle generated according to a deviation amount between the target position information and the rotational position information. (Configuration 3) The control device according to configuration 2, wherein the drive control unit generates the drive signal using a drive counter generated by superimposing the target advance angle on the rotational position information. (Configuration 4) The control device according to configuration 3, wherein the drive control unit generates two-phase drive signals shifted by 90° from each other using angle information of the drive counter. (Configuration 5) Further, a pair of Hall sensors outputting two-phase signals shifted by 90° from each other in response to the rotation of the motor, 5. The control device according to any one of configurations 1 to 4, wherein the rotational position information is generated using the two-phase signal. (Configuration 6) 6. The control device according to any one of configurations 1 to 5, wherein the setting unit calculates the amount of fluctuation by using a difference between the target position information and the rotational position information. (Configuration 7) the rotational position information periodically fluctuates in response to rotation of the motor; The control device according to any one of configurations 1 to 6, wherein the setting unit calculates an intermediate value between a maximum value and a minimum value of the amount of periodic fluctuation in one cycle as a central value of the amount of fluctuation. (Configuration 8) Further, a pair of Hall sensors outputting two-phase signals shifted by 90° from each other in response to the rotation of the motor, the rotational position information periodically fluctuates in response to rotation of the motor; 8. The control device according to any one of configurations 1 to 7, wherein the periodic fluctuation is synchronized with the phase of the two-phase signal. (Configuration 9) the rotational position information periodically fluctuates in response to rotation of the motor; 9. The control device according to any one of configurations 1 to 8, wherein the periodic fluctuation is synchronized with a rotational position of the motor. (Configuration 10) A moving member that moves in response to rotation of the motor; a detection unit that outputs a reference signal indicating a reference position set on the moving member, the setting unit sets the coordinate origin of the rotational position information based on acquisition of the reference signal; The control device according to any one of configurations 1 to 9, characterized in that the drive control unit selects open control while the setting unit is setting the coordinate origin of the rotational position information, and selects advance angle control after the setting unit sets the coordinate origin of the rotational position information. (Configuration 11) 11. The control device according to claim 1, wherein the setting unit sets the coordinate origin of the rotational position information so as to coincide with the coordinate origin of the target position information. (Configuration 12) A control device according to any one of claims 1 to 11; The motor; a lens that moves in response to rotation of the motor; a position detection unit that detects the position of the lens, The position detection unit detects a reference position set on the lens, The imaging device according to the present invention is characterized in that the setting unit sets the coordinate origin of the rotational position information in synchronization with a timing at which the reference position is detected by the position detection unit. generating target position information for a motor; acquiring rotational position information of the motor; generating a drive signal for the motor in response to a deviation between the target position information and the rotational position information; a step of setting an origin of coordinates of the rotational position information in accordance with a difference between a central value of the fluctuation amount of the rotational position information and the fluctuation amount of the rotational position information.

[0079] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0080] 101 Stepping motor (motor) 203 Microcomputer (control device) 205 Encoding processing unit (acquisition unit) 206 Target position setting section (generation section) 207 Coordinate origin setting section (setting section) 208 Lead angle / power rate control section (drive control section) 209 Drive waveform generator (drive control unit)

Claims

1. A generating unit that generates target position information of a motor; an acquisition unit for acquiring rotational position information of the motor; a drive control unit that generates a drive signal for the motor in accordance with a deviation amount between the target position information and the rotational position information; a setting unit that sets a coordinate origin of the rotational position information according to a difference between a central value of a fluctuation amount of the rotational position information and the fluctuation amount of the rotational position information.

2. 2. The control device according to claim 1, wherein the drive control unit generates the drive signal by using a target advance angle that is generated in accordance with an amount of deviation between the target position information and the rotational position information.

3. 3. The control device according to claim 2, wherein the drive control unit generates the drive signal by using a drive counter generated by superimposing the target advance angle on the rotational position information.

4. 4. The control device according to claim 3, wherein the drive control unit generates two-phase drive signals shifted by 90 degrees from each other by using the angle information of the drive counter.

5. The motor further includes a pair of Hall sensors that output two-phase signals that are shifted by 90° from each other in response to rotation of the motor, 5. The control device according to claim 1, wherein the rotational position information is generated using the two-phase signal.

6. 5. The control device according to claim 1, wherein the setting unit calculates the amount of fluctuation by using a difference between the target position information and the rotational position information.

7. the rotational position information periodically fluctuates in response to rotation of the motor; 5. The control device according to claim 1, wherein the setting unit calculates an intermediate value between a maximum value and a minimum value of the amount of periodic fluctuation in one cycle of the periodic fluctuation as a central value of the amount of fluctuation.

8. The motor further includes a pair of Hall sensors that output two-phase signals that are shifted by 90° from each other in response to rotation of the motor, the rotational position information periodically fluctuates in response to rotation of the motor; 5. The control device according to claim 1, wherein the periodic fluctuation is synchronized with the phase of the two-phase signal.

9. the rotational position information periodically fluctuates in response to rotation of the motor; 5. The control device according to claim 1, wherein the periodic fluctuation is synchronized with a rotational position of the motor.

10. A moving member that moves in response to rotation of the motor; a detection unit that outputs a reference signal indicating a reference position set on the moving member, the setting unit sets the coordinate origin of the rotational position information based on acquisition of the reference signal; 5. The control device according to claim 1, wherein the drive control unit selects open control while the setting unit is setting the coordinate origin of the rotational position information, and selects advance angle control after the setting unit has set the coordinate origin of the rotational position information.

11. 5. The control device according to claim 1, wherein the setting unit sets the coordinate origin of the rotational position information so as to coincide with the coordinate origin of the target position information.

12. A control device according to any one of claims 1 to 4; The motor; a lens that moves in response to rotation of the motor; a position detection unit that detects the position of the lens, The position detection unit detects a reference position set on the lens, The imaging device according to claim 1, wherein the setting unit sets the coordinate origin of the rotational position information in synchronization with a timing at which the reference position is detected by the position detection unit.

13. generating target position information for a motor; acquiring rotational position information of the motor; generating a drive signal for the motor in response to a deviation between the target position information and the rotational position information; a step of setting an origin of coordinates of the rotational position information in accordance with a difference between a central value of the fluctuation amount of the rotational position information and the fluctuation amount of the rotational position information.

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