JP2009063702A - Imaging apparatus, its motor control method and motor control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make an iris (diaphragm of a lens) surely reach a target position. <P>SOLUTION: A correction amount measuring means 1a controls a motor 2a and measures the position of the iris after drive when the iris is driven in an opening direction to the predetermined target position, and the position of the iris after drive when the iris is driven in a closing direction to the predetermined target position similarly. Then, it measures correction amount of the target position for eliminating deviation of the position of the iris after drive in accordance with a difference of the driving direction, and stores it in a correction amount storage means 1b. When the target position is set, a target position correction means 1c detects a control direction to the target position, retrieves correction amount corresponding to the control direction and extracts it from the correction amount storage means 1b. It corrects the target position according to the correction amount and controls the motor 2a so as to drive the iris to the correction target position which has been corrected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image pickup apparatus, a motor control method thereof, and a motor control program, and more particularly to an image pickup apparatus that adjusts an iris opening area by controlling a motor that drives an iris, a motor control method thereof, and a motor control program.

  Conventionally, an imaging apparatus controls the aperture area of an iris (lens diaphragm) by a servo mechanism and adjusts the amount of light input. FIG. 14 is a block diagram showing an example of a servo mechanism for controlling a conventional iris.

  The motor control unit 900 inputs a hall value (d) corresponding to the current position of the iris detected by the hall 911, and a pulse for instructing the motor 910 so that the hall value (d) converges to the target position (a). Feedback control is performed to adjust the duty ratio of a width modulation signal PWM (Pulse Width Modulation) (c). Due to the mechanical structure, there is a hysteresis amount corresponding to the control direction and control amount in the iris position control. Accordingly, even if the instructed target position (a) is the same, the hall value (d) after driving depends on the amount of hysteresis depending on whether the control direction is an opening direction that increases the opening area or a closing direction that narrows the opening area. Deviation occurs. For this reason, it is necessary to perform feedback control to converge the hall value (d) to the target position (a).

  Specifically, the hole value (d) detected by the hole 911 is amplified by the AMP 903, converted into a digital value by the ADC 904, and then input to the IR filter IIR 905 as the hole value AD (e). After being converted to the current position (p) by increasing the accuracy in IIR 905, the difference from the target position (a) is input to the PID 901. The PID 901 inputs a difference and calculates a motor control amount based on a servo parameter (b) that determines coefficients of proportional compensation (P), integral compensation (I), and differential compensation (D). The control amount is output to the motor 910 via the driver 902 as PWM (c). By repeating these procedures, the current position of the iris was converged to the target position.

In order to shorten the convergence time, a servo mechanism has been proposed in which the current position is corrected in advance by a position correction amount corresponding to the hysteresis amount (see, for example, Patent Document 1).
JP 61-110124 A

  However, in feedback control, there is a risk that the current position will not converge depending on the servo design, such as the servo parameter value, and there is a risk of oscillation (hunting) near the target position. There are problems such as delays.

  In order to minimize the convergence time to the target position and avoid the phenomenon that the Hall value indicating the current position with respect to the specified target position oscillates, it is necessary to vary the servo parameters in PID control during feedback control. There is. However, since the variable amount and variable timing of the servo parameters differ depending on the motor characteristics and the use environment, the setting is not easy and sufficient verification is required.

  Also, if a deviation from the target position corresponding to the hysteresis amount appears in the Hall value representing the current position, the current position can be converged to the target position by feedback control even if a convergence time is required. Further, as described in Patent Document 1, if a correction value for the hysteresis amount can be set in advance, the convergence time can be further shortened. However, due to the characteristics of the iris, when the hysteresis amount does not appear in the Hall value, that is, even if the Hall value is the same value, the aperture area of the iris is actually slightly different, and the input light quantity may be different. The function of the iris is to adjust the amount of light input by adjusting the opening area, and it is not desirable that such a deviation occurs. However, in the conventional motor control, feedback control is performed to converge the current position according to the Hall value to the target position. It was difficult to equalize regardless of the control direction and control amount.

  As described above, in the conventional motor control, it has been difficult to perform position control so that the disadvantages (oscillation, convergence delay, and hysteresis) of feedback control are eliminated and the target position is reliably reached. In addition, it has been difficult to make the amount of light input through the iris uniform regardless of the control direction or the control amount.

  The present invention has been made in view of the above points, and provides an imaging apparatus, a motor control method thereof, and a motor control program that can eliminate the drawbacks of feedback control and reliably reach a target position. Objective.

  In the present invention, in order to solve the above-described problem, the imaging apparatus includes a correction amount measuring unit, a correction amount storage unit, and a target position correction unit, and controls an iris driving area by controlling a motor that drives the iris. Is provided. The correction amount measuring means instructs the motor to drive the iris to the predetermined target position in the opening direction, and instructs the motor to drive the iris to the predetermined target position in the closing direction. The position of the iris when it is driven to go is detected. Then, the correction amount of the target position that eliminates the displacement of the position after driving the iris is measured in at least one control direction. The correction amount storage means stores the correction amount measured by the correction amount measurement means. When the target position is instructed, the target position correction unit extracts a correction amount corresponding to the control direction up to the target position from the correction amount storage unit, and corrects the target position using the extracted correction amount. Then, an instruction to drive the iris to the corrected correction target position is output to the motor.

  According to such an imaging apparatus, first, the motor is controlled by the correction amount measuring unit, and the iris position when the iris is driven to the predetermined target position in the opening direction and the predetermined target in the closing direction are the same. The iris position when driven to the position is measured. The opening direction is a driving direction that increases the opening area of the iris and increases the amount of light input. The closing direction refers to a driving direction that restricts the aperture area of the iris and reduces the amount of input light. The iris has a hysteresis amount. Even if the iris is driven at the same target position, the position after driving is shifted due to a difference in the control direction or the like. Therefore, the iris is driven in each control direction, and based on the measured position, the correction amount of the target position for eliminating the position shift after the iris drive is measured in at least one control direction. The measured correction amount is stored in the correction amount storage means. When the target position is set, the target position correcting means searches for a correction amount corresponding to the control direction up to the target position and extracts it from the correction amount storage means. Then, the target position is corrected by the correction amount, and the motor is controlled so that the iris is driven to the corrected target position. Thereby, if the target position is the same, the iris is driven to the same position regardless of the control direction.

  Further, in order to solve the above-mentioned problem, in the motor control method for adjusting the iris opening area by controlling the motor that drives the iris, the correction amount measuring means has a predetermined target position in the opening direction of the iris in advance in the motor. The position of the iris when it is driven by driving the iris until it is driven, and the position of the iris when the motor is driven by driving the iris to the predetermined target position in the closing direction is detected. A procedure for measuring the correction amount of the target position for eliminating the positional deviation after driving in at least one control direction and storing the measured correction amount in the correction amount storage means, and the target position correction means indicates the target position Then, the correction amount corresponding to the control direction to the target position is extracted from the correction amount storage means, the target position is corrected using the extracted correction amount, and the corrected correction target is corrected. The motor control method characterized by comprising a step of outputting to the motor a command for driving the iris position, and is provided.

  According to such a motor control method, the iris is driven in advance toward the same target position in the opening direction and the closing direction, and a deviation of the position after driving is detected. Then, the correction amount of the target position for eliminating the detected deviation is measured and stored in the correction amount storage means. When the target position is input, the correction amount corresponding to the control direction up to the target position is extracted from the correction amount storage means, the target position is corrected with the extracted correction amount, and the corrected target position is output to the motor.

  According to the present invention, in the motor control for driving the iris of the image pickup apparatus, a target position correction amount that eliminates a control error caused by the hysteresis amount is measured in advance. When the target position is instructed, the target position is corrected using the measured correction amount, and the motor is controlled using the corrected target position. As a result, it is possible to eliminate the control error due to the hysteresis amount that has occurred due to the difference in the control direction, and to ensure that the iris reaches the target position. Further, since the target position is appropriately corrected, it is not necessary to perform feedback control by the servo mechanism, and problems (oscillation, convergence delay, and hysteresis) that the servo mechanism has can be solved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a conceptual diagram of the invention applied to the embodiment.
The motor control unit 1 includes a correction amount measuring unit 1a for measuring a correction amount, a correction amount storage unit 1b for storing the correction amount, a target position correcting unit 1c for instructing a target position for driving the motor, and an instructed target position. Is controlled by the motor 1a that drives an iris (not shown) of the imaging apparatus, and adjusts the opening area of the iris.

  The correction amount measuring unit 1a outputs a measurement target position (t) to the driver 1d to drive the motor 2a, and measures a correction amount for eliminating a control error caused by iris hysteresis. The measured correction amount is stored in the correction amount storage means 1b. Since the correction amount is used for correcting a control error due to hysteresis, it is assumed as a hysteresis correction amount (h) in the following description.

  Specifically, for example, a predetermined measurement target position (t1) is set in a state where the iris is most narrowed. Then, the measurement target position (t1) is output to the driver 1d to instruct the motor 2a, and the iris is driven in the opening direction to the measurement target position (t1). The position after driving is detected by the hole value (d11) output by the hole 2b at that time. If necessary, the luminance (y11) is also detected. Next, in the state where the iris is most opened, the same measurement target position (t1) as that when driving in the opening direction is output to the driver 1d to instruct the motor 2a, and the iris is moved to the measurement target position (t1). Drive in the closing direction. The position after driving is detected by the Hall value (d12), and the luminance (y12) is also detected as necessary. Here, there is a difference between the Hall value (d11) when driven in the opening direction and the Hall value (d12) when driven in the closing direction according to the amount of hysteresis. Therefore, a predetermined hole value associated with a predetermined measurement target position (t1) is set as a reference detection position, and a target position where the hole value matches the reference detection position in each control direction is measured. For this reason, the Hall value and the reference detection position are collated. If they do not match, the target position at the time of driving is changed, the iris is driven again, the Hall value is detected, and processing from the collation is performed. repeat. In this way, the drive target position where the Hall value matches the reference detection position is measured for each control direction. The difference between the driving target position thus measured and the predetermined measurement target position (t1) is set as a hysteresis correction amount (h1) and stored in the correction amount storage means 1b. In this case, the hysteresis correction amount is measured for both control directions. Further, similarly, a hysteresis correction amount that matches the luminance (y) can also be obtained. If the reference detection position to be set is a detection position that is detected as a Hall value when the iris is driven in one control direction, only the hysteresis correction amount needs to be obtained for the other control direction. Further, the correction amount measurement process need not be frequently performed. Therefore, if it is executed once at the time of product shipment or power supply to the imaging device, the measured hysteresis correction amount (h) can be used in the subsequent processing.

In the correction amount storage means 1b, the hysteresis correction amount (h) measured by the correction amount measurement means 1a is stored in association with the control direction.
When the target position (a) is input, the target position correcting means 1c detects the control direction based on the target position (a) and the previously set target position, and a hysteresis correction amount ( h) is extracted from the correction amount storage means 1b. Then, the target position (a) is corrected with the extracted hysteresis correction amount (h), and the corrected target position (A) is output to the driver 1d.

  The driver 1d inputs the corrected target position (A) subjected to hysteresis correction from the target position correcting means 1c, and instructs the motor 2a to perform PWM (c) instructing to move the iris to the corrected target position (A). Output.

  The operation of the motor control unit 1 having such a configuration will be described. Hereinafter, a case where the hysteresis correction amount (h) in the other control direction is measured so as to match the detection position in one control direction will be described.

  First, the correction amount measuring unit 1a measures the hysteresis correction amount (h) and stores it in the correction amount storage unit 1b. The correction amount measuring unit 1a outputs a predetermined measurement target position (t1) to the driver 1d to control the motor 2a, and the measurement target position (t1) in the control direction of either the opening direction or the closing direction of the iris. ). Then, the position of the iris after driving is detected by the Hall value (d) and, if necessary, the luminance (y). The detected hole value is defined as a hole value (d11), and the luminance is defined as luminance (y11). The detected hole value (d1) and luminance (y1) are held inside. Next, the iris is driven to a predetermined measurement target position (t1) in the direction opposite to the direction in which the Hall value (d1) and the luminance (y1) are detected. It is assumed that the detection position is the Hall value (d12) and the luminance (y12).

  Even if the measurement target position (t1) is the same, the Hall value (d12) and the luminance (y12) in different control directions and the Hall value (d11) and the luminance (y11) are shifted according to the hysteresis amount. Occurs. Since the hall value (d) changes according to the target position, the hall position (d11) when the hall position (d12) is driven in the opposite control direction by changing the target position from the measurement target position (t1). ) To measure the target position for driving (t2) that is the same as (1). The difference between the measured drive target position (t2) and the original measurement target position (t1) is the hysteresis correction amount (h1). If necessary, the same processing is performed for luminance (y). The hysteresis correction amount (h1) measured in this way is stored in the correction amount storage means 1b.

  When the hysteresis correction amount (h) is stored in the correction amount storage unit 1b, the target position correction unit 1c corrects the target position (a) every time the target position (a) is set, and the corrected correction is performed. Feed forward control is performed to drive the motor 2a using the target position (A). When the target position (a) is input, the control direction to the target position (a) is detected, and the hysteresis correction amount (h) corresponding to the control direction is extracted. The target position (a) is corrected using the hysteresis correction amount (h), and the corrected target position (A) is generated and output to the driver 1d. The driver 1d converts the correction target position (A) into PWM (c) and outputs it to the motor 2a. Thereby, the motor 2a drives the iris to the correction target position (A). For example, when correcting the target position when driving in the closing direction, the target position (a) is driven at the corrected target position (A) corrected by the hysteresis correction amount (h1), and as a result, the other control direction (here) Then, it is driven to the same position as the detection position (target position (a)) when driven in the opening direction.

  Thus, according to the present invention, it is possible to eliminate a control error due to hysteresis that has occurred depending on the control direction and the control amount. In addition, since the target position is corrected using the actually measured hysteresis correction amount (h), the target position can be reliably reached by one drive. This eliminates the need for feedback control for converging the current position to the target position, thereby eliminating the disadvantages of feedback control (oscillation, convergence delay, and hysteresis). In addition, it is not necessary to perform a detailed servo design or to secure a sufficient verification time.

Hereinafter, embodiments will be described in detail with reference to the drawings.
FIG. 2 is a diagram illustrating a configuration of the imaging apparatus according to the embodiment of the present invention. The imaging apparatus according to the embodiment includes a lens 301, an iris 302, an imager 303, a DSP (Digital Signal Processor) 304, a camera unit of a monitor 305, a motor control unit 100 that drives the iris 302, a motor 201, and a hole 202. And an iris driving unit.

  Image light from a subject (not shown) is taken into the image pickup device by the lens 301 and irradiated onto the image pickup surface of the imager 303 including the image pickup device via the iris 302. The iris 302 is driven by the iris driving unit to adjust the amount of light applied to the imager 303 by changing the opening area. Usually, the aperture stop according to the aperture area of the iris is represented by an F value. The imaging signal captured by the imager 303 is subjected to signal processing such as correction processing by the DSP 304 and is output to the monitor 305 or the like as a video signal. The DSP 304 has a built-in brightness detection circuit that detects the level of the imaging signal. The level of the imaging signal is input to the motor control unit 100 as luminance (y).

  When the F value is instructed, the motor control unit 100 drives the motor 201 in accordance with the F value and adjusts the opening area of the iris 302. The hall value (d) corresponding to the current position of the iris generated by the hall 202 is input, the PWM (c) is output, and the motor 201 is controlled. The F value may be set directly by the user via an instruction input unit (not shown) or may be set in the apparatus by an auto iris function that automatically adjusts the iris in order to keep the input luminance constant.

  The motor control unit 100 includes, for example, an MPU (Micro Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory), and exchanges data with the DSP 304 and the like via a bus. The ROM stores a program for causing the MPU to execute processing procedures such as motor control processing and correction amount measurement processing. Various data necessary for processing by the MPU is stored in the RAM. The MPU sequentially executes programs stored in the ROM, and performs motor control processing and correction amount measurement processing.

Here, the hysteresis generated by the motor control of the iris will be described.
FIG. 3 is a diagram showing hysteresis generated by the motor control of the iris. The horizontal axis indicates the target position (a), and the vertical axis indicates the detection position (p) represented by the Hall value (d). The vertical axis may be a Hall value (d).

  The position of the iris is mechanically controlled between a mechanical open with the maximum aperture and a mechanical close with the minimum aperture. In the figure, mechanical open and mechanical close are indicated by a one-dot chain line. Optically, the input light quantity can be changed using the optical area between the optical open with the maximum light quantity corresponding to the mechanical open and the optical close with the minimum light quantity corresponding to the mechanical close. . In the figure, the optical open and the optical close are indicated by a two-dot chain line. Further, in the following description, for convenience, the target position (a) at the time of optical open is 300H, the target position (a) at the time of optical close is C00H, and the target position (a) at the intermediate position of the optical area is set. 800H.

  Here, an open-to-close 401 indicated by a solid line indicates a relationship between the target position (a) and the detection position (p) when the iris is changed in the closing direction, that is, from the optical open to the optical close. Yes. That is, when the iris is driven from optical open to optical close (direction in which the aperture area is controlled to reduce the light amount to the imager), the relationship between the target position (a) and the detection position (p). Transitions on open to close 401. A close-to-open 450 indicated by a dotted line indicates a relationship between the target position (a) and the detection position (p) when the iris is changed from the mechanical close to the mechanical open. . In other words, when driving the iris from optical close to optical open (direction to control to increase the aperture area and increase the amount of light to the imager), the relationship between the target position (a) and the detection position (p) is closed. Transition on to open 450. Therefore, even when driven at the same target position, the detection position differs depending on whether the control direction is the open direction or the close direction. For example, when driven in the opening direction toward the target position t1 (800H), it moves on the close to open 450 and moves to the detection position Pβ. On the other hand, when driven in the closing direction toward the target position t1 (800H), it moves on the open-to-close 401 and moves to the detection position Pα. That is, even if the same target position is indicated, the opening area of the iris is smaller in the closed-to-open 450 than in the open-to-close 401, and the amount of light to the imager is reduced. Therefore, it is darker when driven in the opening direction than when driven in the closing direction. Note that the open-to-close 401 and the close-to-open 450 have a deviation due to the hysteresis amount, but have the same characteristics such as inclination (the ratio of the change in the detected position to the change in the target position), and the same target position (a ), The detection position shifts by the amount of hysteresis depending on the control direction.

  Note that this hysteresis amount is different for each set even if the same lens is used. Therefore, it is necessary to measure the hysteresis correction amount for each set. Further, the hysteresis amount is constant regardless of the target position (a), the detection position (p), and the control amount within the optical region. For example, the same hysteresis characteristic is exhibited even when control is performed such as changing the maximum movement amount in the optical region at a time. From the above, if the hysteresis correction amount is measured for each set at the time of product shipment or when the product is powered on, the correction can be performed by subsequent motor control.

  The hysteresis correction amount measurement process will be described. FIG. 4 is a diagram illustrating the principle of the hysteresis correction amount measurement process. The figure is an enlarged view of part of FIG. 3 (near the target position t1).

  With respect to the target position t1 (800H), in the driving in the closing direction represented by the open to close 401, the detection position is Pα. On the other hand, in the driving in the opening direction represented by close to open 450, the detection position is Pβ. This shift in the detection position (Pβ−Pα) becomes a control error. Here, when the target position (t1) is instructed, if the detection position when driven in the opening direction is Pα, it coincides with the detection position in the closing direction. Therefore, the target position (t′1) at which the detection position becomes Pα when driven in the opening direction is measured. A difference between the measured target position (t′1) and the original target position (t1) is a hysteresis correction amount (h) 501.

  When an instruction to drive the iris in the opening direction is input, the target position is corrected by subtracting the measured hysteresis correction amount (h) 501 from the input target position (a). Thereby, the detection position when driven in the opening direction and the detection position Pα when driven in the closing direction are the same.

Hereinafter, the motor control unit 100 is divided into a correction amount measurement process and a target position correction process, and each process will be described in detail.
First, the correction amount measurement process will be described. FIG. 5 is a block diagram illustrating functional blocks for performing correction amount measurement processing of the motor control unit. The same components as those in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted.

  The motor control unit 100 includes a correction amount measurement unit 110 that measures a hysteresis correction amount, a driver 120 that outputs PWM (c) that controls the motor 201, an AMP (amplifier) 140, and an ADC (AD converter, Analog to Digital). Converter) 150. In the figure, target position correction means not related to the description is omitted.

  The correction amount measurement unit 110 includes a detection position correction amount measurement unit 111 that measures the hysteresis correction amount from the detection position, and a luminance correction amount measurement unit 112 that measures the hysteresis correction amount from the luminance.

  The driver 120 converts the target position set by the correction amount measurement unit 110 into PWM (c) and outputs the PWM to the motor 201. The current position of the iris driven by the motor 201 is detected by the hole 202 and output to the motor control unit 100 as a hole value (d). The hall value (d) is amplified by the AMP 140, converted into a digital value by the ADC 150, and then input to the detected position correction amount measuring unit 111 as the hall value AD (e). Further, the luminance (y) at this time is detected by a DSP (not shown) and input to the luminance correction amount measuring unit 112.

  The detection position correction amount measurement unit 111 measures a hysteresis correction amount that matches the detection position during the opening direction drive with the detection position during the closing direction drive based on the detection position represented by the Hall value AD (e). Therefore, the Hall value AD (e1) detected when the driver 120 is instructed to drive the motor 201 and the iris is driven to a predetermined target position in one of the control directions is measured in advance. In the other control direction, a target position where the hall value AD (e2) coincides with the hall value AD (e1) measured in advance is measured. Whether or not the target positions match is determined by comparing the hall value AD (e2) detected when the iris is driven by shifting the target position in the other control direction and the hall value AD (e1). To do. The difference between the target position corresponding to the hole value AD (e2) when matched and the target position corresponding to the reference hole value AD (e1) is calculated and set as a hysteresis correction amount based on the detected position.

  The luminance correction amount measuring unit 112 measures a hysteresis correction amount that matches the amount of light input to the iris represented by the luminance (y). Therefore, the luminance (y1) detected when the driver 120 is instructed to drive the motor 201 and the iris is driven to a predetermined target position in one of the control directions is measured in advance. A target position where the luminance (y2) detected in the control direction matches the luminance (y1) measured in advance is measured. Hysteresis correction based on the detected luminance by calculating the difference between the target position corresponding to the luminance (y2) when the luminance (y2) and the luminance (y1) coincide with the predetermined target position corresponding to the luminance (y1) Make quantity.

  Hereinafter, the procedure of the hysteresis correction amount measurement process will be described. Here, the hysteresis correction amount for driving the iris with the drive characteristic in the closing direction (open to close 401 in FIG. 3) is measured. That is, a case where the hysteresis correction amount for matching the driving characteristic in the opening direction (close to open 450) with the driving characteristic in the closing direction (open to close 401) is measured will be described. As described above, when the iris is driven in the opening direction, the opening area is narrower and the amount of light is smaller than when the iris is driven in the closing direction with the same target value. Therefore, the following target value correction is performed to make the brightness at the target position when driven in the opening direction coincide with the brightness when driven in the closing direction at the same target position.

FIG. 6 is a flowchart showing a procedure for measuring the hysteresis correction amount based on the Hall value representing the iris detection position.
When a set start condition such as input of an adjustment instruction or power-on is satisfied, the process is started.

  [Step S101] The detection position correction amount measuring unit 111 instructs the driver 120 to drive to the optical open (target position 300H in FIG. 3), and drives the iris to the optical open (maximum aperture).

  [Step S102] The detected position correction amount measuring unit 111 instructs the driver 120 to specify an intermediate value of the optical area (target position t1 (800H) in FIG. 3) as the target position, and drives the iris to the middle of the optical area. As a result, the iris transits from open to close 401 and is driven in the closing direction, and is moved from the optical open (300H) to the intermediate point t1 (800H). The detected position (Hall value ADα) after movement is stored in the memory and held.

[Step S103] Next, the driver 120 is instructed to drive to the optical close (target position C00H in FIG. 3), and the iris is driven to the optical close (minimum aperture).
[Step S104] The driver 120 is instructed as the target position the intermediate value of the optical region (t1 (800H) in FIG. 3), and drives the iris to the middle of the optical region. As a result, the iris transits from close to open 450 and is driven in the open direction, and is moved from the optical close (C00H) to the intermediate point (t1 (800H)). The detection position (Hall value ADβ) after movement is detected.

  [Step S105] The detection position ADα at the time of driving in the closing direction (transition on open to close 401) detected in step S102 is compared with the detection position ADβ at the time of driving in the opening direction (transition on close to open 450). . If they match, the process proceeds to step S107, and if they do not match, the process proceeds to step S106.

  [Step S106] If the detection position ADα during driving in the closing direction (transition on open-to-close 401) and the detection position ADβ during driving in the opening direction (transition on close-to-open 450) do not match, open The target position of the direction drive is advanced, and the driver 120 is instructed to drive the iris. In the case of the example of FIG. 3, the target position (A) is updated to the target position (A-1) by proceeding by 1 in the opening direction. Thereby, the iris is moved in the opening direction. Then, the detected position (hole value ADβ) after the movement is read, and the process returns to step S105.

  [Step S107] When the detection position ADα at the time of driving in the closing direction (transition on open to close 401) coincides with the detection position ADβ at the time of driving in the opening direction (transition on close to open 450), the driving in the opening direction is performed. The difference between the target position and the target position for the closing direction drive is calculated as a hysteresis correction amount. The hysteresis correction amount is calculated by subtracting the target position (t1 (800H)) corresponding to the detection position ADα from the target position (800 + hys) corresponding to the detection position ADβ, where the hysteresis correction amount is hys. The calculated hysteresis correction amount is stored in the storage means, and the process ends.

  By executing the above processing procedure, it is possible to calculate a hysteresis correction amount that causes the drive characteristic in the open direction (close to open 450) to transition to the drive characteristic in the close direction (open to close 401).

Next, processing for measuring a hysteresis correction amount based on luminance will be described. FIG. 7 is a flowchart showing a procedure for measuring the hysteresis correction amount based on the luminance.
Similar to the hysteresis correction amount measurement processing based on the detection position, the processing is started when a set start condition such as input of an adjustment instruction or power-on is satisfied.

  [Step S111] The luminance correction amount measuring unit 112 instructs the driver 120 to drive to the optical open (target position 300H in FIG. 3), and drives the iris to the optical open (maximum aperture).

  [Step S112] The luminance correction amount measuring unit 112 instructs the driver 120 to specify an intermediate value of the optical region (target position t1 (800H) in FIG. 3) as the target position, and drives the iris to the middle of the optical region. As a result, the iris is driven in the closing direction (transition on open to close 401) and moved from the optical open (300H) to the intermediate point (t1 (800H)). The luminance (LVα) after movement is stored in the memory and held.

[Step S113] Next, the driver 120 is instructed to drive to the optical close (target position C00H in FIG. 3), and the iris is driven to the optical close (minimum aperture).
[Step S114] The driver 120 is instructed as the target position the intermediate value of the optical region (t1 (800H) in FIG. 3), and the iris is driven to the middle of the optical region. As a result, the iris is driven in the opening direction (transition on the close-to-open 450) and moved from the optical close (C00H) to the intermediate point (t1 (800H)). The brightness (LVβ) after movement is detected.

  [Step S115] The brightness LVα in the closed direction (transition on open to close 401) detected in step S112 is compared with the brightness LVβ in the open direction (transition on close to open 450). If they match, the process proceeds to step S117, and if they do not match, the process proceeds to step S116.

  [Step S116] If the brightness LVα in the closed direction (transition on open to close 401) drive and the brightness LVβ in the open direction (transition on close to open 450) do not match, open direction drive is performed. And the driver 120 is instructed to drive the iris. In the case of the example of FIG. 3, the target position (A) is updated to the target position (A-1) by proceeding by 1 in the opening direction. Thereby, the iris is moved in the opening direction. Then, the detected position (luminance LVβ) after movement is read, and the process returns to step S115.

  [Step S117] When the brightness LVα in the closed direction (transition on open to close 401) and the brightness LVβ in the open direction (transition on close to open 450) coincide with each other, the difference in target position is calculated. Calculate the hysteresis correction amount. The hysteresis correction amount is calculated by subtracting the target position (t1 (800H)) corresponding to the luminance LVα from the target position (800H + hys) corresponding to the luminance LVβ. The calculated hysteresis correction amount is stored in the storage means, and the process ends.

  By executing the above processing procedure, it is possible to calculate a hysteresis correction amount that causes the drive characteristic in the open direction (close to open 450) to transition to the drive characteristic in the close direction (open to close 401).

  In the above description, the case where the correction amount measurement based on the detection position and the correction amount measurement based on the luminance are performed has been described. However, the correction amount measurement may be performed in combination. The correction amount for matching the brightness is measured to correct a case where the brightness is different even if the detection position represented by the hole value is the same. Therefore, after the correction amount is measured based on the detection position, the correction amount is further measured using the luminance.

  For example, in the correction process based on the detection position shown in FIG. 6, when the iris is driven in the closing direction (transition on open to close 401) in step S102, the brightness LVα is detected and held together with the current position ADα. deep. In step S105, the current position ADβ when driven in the opening direction (transition on close to open 450) is made coincident with the current position ADα when driven in the closing direction (transition on open to close 401). When it is determined that the current luminance LVβ is driven in the opening direction (transition on close to open 450), the current luminance LVβ is shifted in the closing direction (transition on open to close 401). It converges to the current brightness LVα when driven.

  In the above description, the detection position and brightness when driven in the closing direction (transition on open to close 401) are changed to the detection position and luminance when driven in the opening direction (transition on close to open 450). Although the hysteresis correction amount for adjusting the luminance is calculated, the detection position and the luminance when driven in the open direction (transition on close to open 450) are driven in the close direction (transition on open to close 401). It is natural that the hysteresis correction amount can be calculated even when the detected position and the luminance at the same time are combined.

  The hysteresis correction amount thus measured in advance is stored in the memory. When the target position is set, correction is performed based on the hysteresis correction amount so that the same brightness can be obtained regardless of the control direction at the same target position. Hereinafter, the target position correction process will be described.

FIG. 8 is a block diagram showing functional blocks for performing target position correction processing of the motor control unit. The same components as those in FIGS. 2 and 5 are denoted by the same reference numerals, and description thereof is omitted.
The motor control unit 100 includes a driver 120, a target position correction unit 130 that generates a correction target position to be output to the driver 120, an AMP 140, and an ADC 150. In the figure, the correction amount measuring unit 110 that is not related to the description is omitted.

  The target position correction unit 130 includes a correction processing unit 131 that corrects the target position using the hysteresis correction amount, and a minute inversion correction processing unit 132 that corrects the target position when performing minute inversion.

  The corrected target position setting unit 131 calculates the control direction and the control amount based on the input target position (a) and the target position set up to the previous time. When the control direction does not change and when the control direction changes but the control amount is larger than the hysteresis correction amount (h), the target position is corrected by the hysteresis correction amount (h) measured by the correction amount measuring unit 110, and the correction target The value is output to the driver 120. Specifically, first, the control direction is confirmed in order to match the change in the opening direction represented by close to open 450 in FIG. 3 with the change in the closing direction represented by open to close 401. If the control direction is the closed direction (transition on open to close 401), the input target position (a) is output to the driver 120 as it is. On the other hand, if the control direction is the open direction (transition on close to open 450), the correction target position is set by subtracting the hysteresis correction amount (h) from the input target position (a) and output to the driver 120. To do.

  By executing the above processing, the effect that the brightness with respect to the target position (a) becomes uniform regardless of the control direction can be obtained. FIG. 9 is a diagram showing the relationship between the corrected target position after the target position correction and the detected position.

  If the control direction is the open direction (previous target position <current target position), the input target position is subtracted by the hysteresis correction amount. As a result, the close-to-open 450 operates on the corrected close-to-open 451. That is, the brightness (input light amount) of the iris when driven in the open direction is the same as the brightness in the close direction represented by open to close 401.

  On the other hand, when the control direction is reversed and the control amount is smaller than the hysteresis correction amount, the above processing cannot be performed. Accordingly, the minute inversion correction processing unit 132 calculates the control direction and the control amount based on the input target position (a) and the previous target position set up to the previous time. When the control direction is reversed and the control amount is smaller than the hysteresis correction amount (h), the hysteresis correction amount at the time of minute inversion is calculated, and the target position (a) is corrected with the calculated hysteresis correction amount, thereby correcting the target. The position is set and output to the driver 120.

FIG. 10 is a diagram illustrating the relationship between the target position and the detection position when the control direction is reversed. When the control direction is reversed, the iris moves on the hysteresis curve and operates.
For example, when the control direction changes from the closed direction to the open direction at T1, the iris makes a transition on the open to close 401, and on the hysteresis curve represented by open to close → close to open 461 at the point T1. Transition to close-to-open 450. Similarly, when the control direction changes from the closed direction to the open direction at the T2 point, a transition is made on the open to close 401, and a transition is made on the hysteresis curve represented by the open to close → close to open 462 at the T2 point. Then move to Close to Open 450.

  In addition, when the control direction changes from the open direction to the close direction at T3, the transition is made on the close to open 450, and on the hysteresis curve represented by the close to open → open to close 463 at the point T2. Move to Open to Close 410.

  In this way, when the control direction is reversed and the control amount is smaller than the hysteresis correction amount, the brightness of the iris transitions on the hysteresis curves 461, 462, and 463, so that the target position is corrected accordingly. It is necessary to adjust the hysteresis correction amount used in the above. The hysteresis characteristic when the control direction is reversed shows the same characteristic in any control direction.

  Here, adjustment of the hysteresis correction amount according to the control amount when the control direction is reversed will be described. FIG. 11 is a diagram illustrating a method for adjusting the hysteresis correction amount when the control direction is reversed. The figure is an enlarged view of the hysteresis curve of FIG. 10, and the same numbers are assigned to the same parts as in FIG.

At the time of minute inversion where the control amount is smaller than the hysteresis correction amount, the hysteresis characteristic 460 is expressed by an approximate expression, and the hysteresis correction amount used for correction is adjusted based on the approximate expression.
As the approximate expression, for example, a primary approximate expression 471 or a secondary approximate expression 472 is used. In order to increase the accuracy of correction, a second order approximation 472 is used.

Next, the target position correction process will be described. FIG. 12 is a flowchart illustrating a procedure of target position correction processing.
The target position (a) is input to the target position correction unit 130, and the process is started.

  [Step S201] Based on the input target position (a) and the previous target position, a control direction and a control amount are acquired. Then, it is determined whether the control direction is an open direction (closed to open). If so, the process proceeds to step S202; otherwise, the process proceeds to step S206.

  [Step S202] If the control direction is the open direction, it is next determined whether the control direction is reversed and the control amount is equal to or less than the hysteresis correction amount (h), and the condition for the minute reversal process is satisfied. Determine whether or not. If the minute inversion processing condition is satisfied, the process proceeds to step S204; otherwise, the process proceeds to step S203.

  [Step S203] If it is not the minute inversion process, the target position is offset by the hysteresis correction amount (h), and the correction target position is set. The corrected target position is (target position (a) −hysteresis correction amount (h)). The set correction target position is output to the driver 120, and the process ends.

  [Step S204] If it is a minute inversion process (a process in which the control direction is inverted and the control amount is smaller than the hysteresis correction amount), the hysteresis correction amount (h) is adjusted using an approximate expression as shown in FIG. Then, the minute hysteresis correction amount is calculated.

  [Step S205] The target position (a) is offset by the fine hysteresis correction amount (h) after adjustment adjusted in step S204, and a corrected target position is set. The corrected target position is (target position (a) −small hysteresis correction amount (h)). The set correction target position is output to the driver 120, and the process ends.

  [Step S206] When the control direction is not the open direction, it is determined whether the control direction is the reverse direction and the control amount is equal to or less than the hysteresis correction amount (h), and whether or not the condition of the minute inversion process is satisfied. judge. If the minute inversion processing condition is satisfied, the process proceeds to step S207. If not satisfied, the target position (a) is output to the driver 120 without correction, and the process ends.

  [Step S207] If it is a minute inversion process (a process in which the control direction is inverted and the control amount is smaller than the hysteresis correction amount), the hysteresis correction amount (h) is adjusted using an approximate expression as shown in FIG. To do.

  [Step S208] The target position (a) is offset by the adjusted hysteresis correction amount (h) adjusted in step S207, and a corrected target position is set. The corrected target position is (target position (a) −small hysteresis correction amount (h)). The set correction target position is output to the driver 120, and the process ends.

  By executing the above processing procedure, if the control direction is the open direction (closed to open) and the control amount is larger than the hysteresis correction amount, the target position (a) corrected by the hysteresis correction amount (h) ) To drive the iris. When the control direction is the closing direction (open to close) and the control amount is larger than the hysteresis correction amount, the iris is driven at the target position (a) as it is. On the other hand, when the control direction is reversed and the control amount is smaller than the hysteresis correction amount, the hysteresis correction amount is adjusted by an approximate expression of the hysteresis characteristic, and the target position (a) corrected by the adjusted minute hysteresis correction amount is adjusted. Then the iris is driven.

As a result, the brightness of the iris (input light amount) can be made uniform with high accuracy regardless of the control direction, the inversion of the control direction, and the control amount.
Next, F value setting for setting the aperture of the imaging apparatus and processing of the mode control unit will be described. FIG. 13 is a diagram illustrating an example of processing of the mode control unit when the F value of the imaging apparatus is set. In the drawing, the numerical value of the F value is expressed as “F numerical value”, and the target position corresponding to the F value is expressed as “target position (F value)”.

  The smaller the F value, the larger the iris opening area, and the larger the value, the narrower the opening area. The F value instruction may be set by the user to an arbitrary value, or may be set inside the imaging apparatus by automatic exposure or an auto iris function.

  Hereinafter, the change of the F value and the operation of the target position correction unit 130 of the motor control unit 100 at that time will be described. In the following description, when the F value changes by 1.0 or more, it is assumed that the change in the target position is larger than the hysteresis correction amount.

  First, assume that the user instructs F5.6 in the state of F2.0. A target position (F5.6) corresponding to F5.6 is input to the target position correction unit 130. Further, the F value may be directly input, and the conversion to the target position may be performed in the target position correction unit 130. In the target position correction process (step S211), since the target position (F5.6) is input, the control direction and the control amount are determined. As for the change from F2.0 to F5.6, the control direction is “the closing direction” for narrowing the iris, and the control amount is “control amount ≧ hysteresis correction amount”. Therefore, correction by the hysteresis correction amount is not performed, and the target position (F5.6) is output to the driver 120 as the target position, and the motor is driven. After the end of driving, processing is not performed until the next instruction is input.

  Subsequently, the user instructs F11, and the target position (F11) is input to the target position correction unit 130. In the target position correction process (step S212), the control direction and the control amount are determined, and “closed direction” and “control amount ≧ hysteresis correction amount” are detected. Therefore, the correction by the hysteresis correction amount is not performed, and the target position (F11) is output to the driver 120 as the target position, and the motor is driven. It is the same that the process is not performed until the next instruction input.

  Next, the user instructs F8.0, and the target position (F8.0) is input to the target position correction unit 130. In the target position correction process (step S213), the control direction and the control amount are determined, and “open direction” and “control amount ≧ hysteresis correction amount” are detected, respectively. Since the direction is the open direction, the target position is corrected with a hysteresis correction amount (hys in the figure). Offset is performed with the hysteresis correction amount (hys), and “target position (f8.0) −hys” is output to the driver 120 as the target position to drive the motor. It is the same that the process is not performed until the next instruction input.

  Next, it is assumed that F8.1 is instructed by the automatic exposure function and the target position (F8.1) is input to the target position correction unit 130. In the target position correction process (step S214), the control direction and the control amount are determined, and “the closing direction” and “control amount <hysteresis correction amount” are detected, respectively. Since “control amount <hysteresis correction amount”, the hysteresis correction amount (hys) is adjusted, and the adjusted minute hysteresis correction amount (hys ′) is calculated. The target position is offset by the minute hysteresis correction amount (hys '), and "target position (F8.1) -hys'" is output to the driver 120 as the target position, and the motor is driven. It is the same that the process is not performed until the next instruction input.

  As described above, the target position correction process is started every time the F value is instructed, and the corrected target position is corrected so that the brightness at the instructed F value is uniform regardless of the control direction and the control amount. Calculated. By driving the iris using the corrected target position, it is possible to obtain a desired brightness without time delay.

  Further, since the servo mechanism is not used, it is possible to omit the procedure of designing the variable amount and variable timing of the servo parameter based on the motor characteristics and the use environment and performing sufficient verification in the design process. Also, there is no danger of motor oscillation (hunting) due to servo design errors.

  The above processing functions can be realized by a computer. In that case, a program describing the processing contents of the functions that the imaging apparatus should have is provided. By executing the program on a computer, the above processing functions are realized on the computer. The program describing the processing contents can be recorded on a computer-readable recording medium. Examples of the computer-readable recording medium include a magnetic recording device, an optical disk, a magneto-optical recording medium, and a semiconductor memory. Examples of the magnetic recording device include a hard disk device (HDD), a flexible disk (FD), and a magnetic tape. Optical disks include DVD (Digital Versatile Disc), DVD-RAM, CD (Compact Disc) -ROM, CD-R (Recordable) / RW (ReWritable), and the like. Magneto-optical recording media include MO (Magneto-Optical disk).

  The computer that executes the program stores, for example, the program recorded on the portable recording medium or the program transferred from the server computer in its own storage device. Then, the computer reads the program from its own storage device and executes processing according to the program.

It is a conceptual diagram of the invention applied to embodiment. It is the figure which showed the structure of the imaging device of embodiment of this invention. It is the figure which showed the hysteresis which generate | occur | produces by the motor control of an iris. It is the figure which showed the principle of the hysteresis correction amount measurement process. It is the block diagram which showed the functional block which performs the correction amount measurement process of a motor control part. It is the flowchart which showed the procedure which measures a hysteresis correction amount based on the Hall value showing the detection position of an iris. It is the flowchart which showed the procedure which measures a hysteresis correction amount based on a brightness | luminance. It is the block diagram which showed the functional block which performs the target position correction process of a motor control part. It is the figure which showed the relationship between the correction target position by which target position correction was carried out, and a detection position. It is the figure which showed the relationship between the target position when a control direction is reversed, and a detection position. It is a figure explaining the adjustment method of the hysteresis correction amount at the time of control direction reversal. It is the flowchart which showed the procedure of the correction process of a target position. It is the figure which showed an example of the process of the mode control part when the F value of an imaging device is set. It is the block diagram which showed an example of the servo mechanism which controls the conventional iris.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Motor control part, 1a ... Correction amount measuring means, 1b ... Correction amount storage means, 1c ... Target position correction means, 1d ... Driver, 2a ... Motor, 2b ... ·hole

Claims (10)

In an imaging apparatus that adjusts the opening area of the iris by controlling a motor that drives the iris,
The motor is instructed to drive the iris to a predetermined target position in the opening direction, and the motor is instructed to drive the iris in the closing direction to the predetermined target position. A correction amount measuring means for detecting a position of the iris when the iris is driven, and measuring a correction amount of the target position for canceling the position shift after the driving of the iris in at least one control direction;
Correction amount storage means for storing the correction amount measured by the correction amount measurement means;
When the target position is instructed, a correction amount corresponding to the control direction up to the target position is extracted from the correction amount storage means, the target position is corrected using the extracted correction amount, and the corrected correction is performed. Target position correcting means for outputting an instruction to drive the iris to a target position to the motor;
An imaging device comprising:   The target position correcting means performs feedforward control that corrects the target position only when the target position is newly instructed and outputs an instruction to drive the iris to the corrected target position to the motor. The imaging apparatus according to claim 1.   The correction amount measuring means collates a detection position detected after the iris is driven in a predetermined control direction with a reference detection position set corresponding to the predetermined target position. The process of changing the driving target position when driven and driving the iris in the predetermined control direction is repeated until the detection position matches the reference detection position, and the driving target position when they match is determined. The imaging apparatus according to claim 1, wherein the correction amount is measured and the correction amount is calculated from a difference between the driving target position and the predetermined target position.   The correction amount measuring means uses the detection position detected when the iris is driven in one control direction as the reference detection position, and the detection position when driven in the other control direction is the reference detection position. The imaging apparatus according to claim 3, wherein the correction target is measured by detecting the driving target position.   The correction amount measuring means detects the brightness detected according to the amount of light input through the iris when the iris is driven in the opening direction and when the iris is driven in the closing direction. The imaging apparatus according to claim 1, wherein a correction amount of the target position that eliminates a luminance shift after driving the iris is measured in at least one control direction.   The correction amount measuring means calculates a correction amount of a target position that eliminates a position shift after driving of the iris, and further adjusts the correction amount based on luminance after driving of the iris. The imaging apparatus according to claim 5, wherein:   When the detected control direction is a reversal control direction that reverses the previous control direction, the target position correction unit compares the control amount up to the target position with the correction amount, and the control amount is corrected. When the amount is smaller than the amount, a minute correction amount corresponding to the control amount is calculated on the basis of a hysteresis curve representing a position shift after the iris is driven, and the target position is corrected using the calculated minute correction amount. The imaging apparatus according to claim 1, wherein:   The imaging apparatus according to claim 7, wherein the target position correcting unit calculates the minute correction amount using an approximate expression that approximates the hysteresis curve. In the motor control method for adjusting the opening area of the iris by controlling the motor that drives the iris,
The correction amount measuring means instructs the motor to drive the iris in the opening direction to a predetermined target position in advance, and the position of the iris when the motor is driven to the predetermined direction in the closing direction. Detecting the position of the iris when driven by performing an instruction to drive to the target position, and measuring a correction amount of the target position for eliminating the position shift after the driving of the iris in at least one control direction; A procedure for storing the measured correction amount in a correction amount storage means;
When the target position correction means is instructed to the target position, the correction amount corresponding to the control direction up to the target position is extracted from the correction amount storage means, and the target position is corrected using the extracted correction amount. And a procedure for outputting an instruction to drive the iris to the corrected correction target position to the motor;
A motor control method characterized by comprising: In a motor control program for controlling a motor for driving the iris and adjusting the opening area of the iris,
Computer
The motor is instructed to drive the iris to a predetermined target position in the opening direction, and the motor is instructed to drive the iris in the closing direction to the predetermined target position. The position of the iris when the lens is driven, and measuring the correction amount of the target position that eliminates the deviation of the position after driving the iris in at least one control direction, and correcting the measured correction amount Correction amount measuring means stored in the amount storage means;
When the target position is instructed, a correction amount corresponding to the control direction up to the target position is extracted from the correction amount storage means, the target position is corrected using the extracted correction amount, and the corrected correction is performed. Target position correcting means for outputting an instruction to drive the iris to a target position to the motor;
A motor control program that functions as a computer program.

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