JP2001273035A - Servo control regulation method of control equipment by actuator including shape memory alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform servo-control not only in a stable driving condition but also with less error and highly precisely in a control equipment with an actuator including shape memory alloy. SOLUTION: A gain setting in a servo control circuit is optimized to a prescribed tolerance. An actual driving position of the drived parts after the optimization is detected by the means for detecting the present position and the difference between a concerned actual driving and target position is measured. The measured difference is stored in the control equipment. The servo control considering this stored difference makes it possible to be performed not only in a stable driving condition but also with less error and highly precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a servo control adjusting method in a control device for performing servo control using an actuator including a shape memory alloy.

[0002]

2. Description of the Related Art In recent years, a need has arisen for a small position control mechanism that can be used also in a camera shake correction mechanism of a lens shutter camera, for example. An actuator using a shape memory alloy and a spring can be considered as an actuator that meets such a demand. Until now, as a method of controlling an actuator using a shape memory alloy, only on / off control for simply using the actuator as a switch has been disclosed. See also "Systems and Control Vol. 29
No. 5: Kuribayashi 1985 ”introduces a mathematical model of control elements using a shape memory alloy and PID control, but does not mention the specific method.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a control device for servo-controlling the position of a driven member using an actuator including a shape memory alloy, and such a control device. It is an object of the present invention to perform not only a stable driving state but also highly accurate servo control with a small error.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to effectively solve the above-mentioned problems, and provides a servo control adjusting method having the following features. .

[0005] The servo control adjustment method of the present invention is an adjustment method in the following control device. In the control device, an actuator is composed of "a shape memory alloy whose shape is stored in a predetermined size" and "biasing means for changing the size by applying an external force to the shape memory alloy". And the position of the driven member by this actuator is the first direction in which the shape memory alloy returns to the memory size,
Servo control is performed in the second direction in which the urging means changes the dimension of the shape memory alloy. In addition, the device
"Target position determining means for determining a target position to move the driven member", "current position detecting means for detecting the current position of the driven member", and "servo control based on the information on the target position and the current position." Servo control circuit to perform ". Preferably, a spring such as a bias spring is used as the biasing means.

[0006] The servo control adjustment method of the present invention for such a control device includes an "optimizing step for optimizing the gain setting of the servo control circuit within a predetermined allowable range" and a "driven member after the optimization." The actual driving position is detected by the current position detecting means, and an actual measurement step of actually measuring a difference between the actual driving position and the target position '' and a `` storage step of storing the actually measured difference in the control device itself '' are performed. Including. It is preferable that the servo control circuit of the control device includes a “correction circuit that performs correction for suppressing heating of the shape memory alloy in order to stabilize the drive control of the actuator”. In that case,
In the optimization step, optimization is performed including the correction value by the correction circuit.

According to the servo control adjusting method of the present invention, a stable driving state by the servo control is realized, and the difference between the "target position" and the "actual driving position" generated at that time is measured. Is stored in the control device itself. Therefore, by performing the servo control in consideration of the difference (offset error or the like) stored in the device itself, it is possible to perform not only a stable driving state but also a highly accurate servo control with a small error. .

[0008]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

According to the present invention, in each of the X direction (horizontal direction) and the Y direction (vertical direction), a shake amount caused by a camera shake is detected using a gyro (angular velocity sensor). Then, the correction optical system arranged in the lens barrel is driven in a direction to cancel camera shake. The correction optical system, as described later,
It is driven by an actuator using a shape memory alloy (SMA) and a bias spring. In general, a camera shake generates a sine wave vibration of about 10 Hz at the maximum in the camera, but the present invention corrects such a camera shake.

FIG. 1 shows the overall configuration of a camera shake correction system according to the present invention. A gyro a2 for the X direction and a gyro a3 for the Y direction are arranged in the camera body a1, and angular velocities due to camera shake in the X and Y directions are independently detected. The shake detection circuit a4 includes a filter circuit that cuts signal noise included in the angular velocity signal from each gyro, an integration circuit that converts the angular velocity signal into an angle signal, and the like. The shake amount detection unit a5 captures the angle signal from the shake detection circuit a4 at predetermined time intervals, and outputs the camera shake amount to the coefficient conversion unit a8. The shake amount in the X direction is output as "detx", and the shake amount in the Y direction is output as "dety".

The sequence control section a7 controls a sequence relating to photographing and camera shake correction. When the release button a6 is half-pressed, preparation for photographing such as photometry and distance measurement is started. When the release button a6 is fully pressed, the state shifts to the shooting state, and the camera shake is corrected in the following sequence. The signal from the gyro is taken into the shake amount detection unit a5, and the shake amounts "detx" and "dety" are detected. The shake amounts "detx" and "dety" obtained by the shake amount detection unit a5 are converted into the actual movement amounts "px" and "py" of the correction optical system by the coefficient conversion unit a8. In the target position calculator a9, the drive signal amounts "drvx" and "drvy" for moving the correction optical system by the movement amounts "px" and "py".
Is calculated. Note that the coefficient conversion unit a8 calculates the optimum coefficient in consideration of the optical performance that changes depending on the solid-state variation and the temperature of the correction optical system when shifting to the shooting preparation.

The target position corrector a10 outputs a correction signal for correcting the target position based on signals from the temperature sensor a12 and the actual drive position taker a14. As will be described in detail later, the actual drive position capturing unit a14 receives a signal indicating the current position of the correction optical system from the lens barrel side position detection sensors a25 and a26, and outputs the signal to the target position correction unit a10. . Based on this signal, the target position correction unit a10 performs correction in consideration of the offset error of the SMA actuator whose performance changes mainly due to a rise in temperature. In the illustrated embodiment, the target position calculation unit a9 forms a target position determination unit. The drive control corrector a11 sets the optimum gain so that the optimum drive performance can be exhibited at each individual and at each temperature, regardless of the SMA actuator, the solid state variation of the drive mechanism, and the change in drive performance due to temperature, and optimizes the drive state. Become The above processing is performed by digital processing using a microcomputer.

A correction optical system a22 is incorporated in the photographing optical system a21. The correction optical system a22 includes an X-direction actuator a24 and a Y-direction actuator a26.
It is driven independently in the X and Y directions. The X-direction position and the Y-direction position of the correction optical system a22 are detected by position detection sensors a25 and a26, respectively. These mechanical configurations will be described below.

FIG. 2 is a plan view for explaining a driving mechanism of the correction optical system. A movable base d9 slidable in the X direction is disposed on a base d19 that is immovable with respect to the camera body. The correction optical system d1 is slidable in the Y direction with respect to the movable table d9. Therefore, the correction optical system d
1 is slidable in both the X and Y directions with respect to the base d19.

The slide mechanism of the correction optical system d1 with respect to the movable table d9 is as follows. On the upper surface of the moving table d9, Y
The two guide rods d3 and d6 extending in the direction are fixed, and the correction optical system d1 is arranged between them. A slide guide that is slidably engaged with each guide rod is fixed to the holding frame d2 of the correction optical system d1. Therefore, the correction optical system d1 is guided by the two guide rods and Y
It is slidable in the direction. The SMA d7 and the bias spring d8 are arranged on the terminal d5 protruding from the one slide guide d4 so as to pull the terminal d5 mutually.

At first, since the "tensile force by the bias spring d8" is larger than the "tensile force by the SMAd7",
The correction optical system d1 is located on the lower side in FIG. When the amount of current supplied to the SMAd 7 is increased from that state, the SMad 7 gradually contracts toward its storage length, and the correction optical system d1 moves upward. Therefore, SMA
By controlling the amount of power to d7, the Y of the correction optical system d1 is controlled.
The position in the direction can be controlled. The control of the position of the movable base d9 in the X direction with respect to the base d19 is performed based on the same principle. Thus, an actuator is constituted by the shape memory alloy and the bias spring, and two such actuators are provided independently for the X direction and for the Y direction.

FIG. 3 shows SMA with respect to applied current.
A hysteresis loop representing the expansion and contraction of is shown. SMA is
Since it is soft and easily deformed in a state lower than the memory temperature,
It is stretched by being pulled by the bias spring. Then, when the storage temperature is reached by heating, the shape returns to the stored shape (dimension). S
The SMA can be expanded and contracted by raising and lowering the temperature by turning on and off the current applied to the MA.

FIG. 4 is an explanatory diagram for explaining a position detection principle for detecting the current position of the correction optical system. The LED e1 is fixed to a holding frame d2 (see FIG. 2) of the correction optical system d1. That is, the LED e1 moves together with the correction optical system d1. The light from the light emitting chip e2 in the LED e1 passes through the slit e3, and the PSD (position sens
(light-emitting device) e4. PSDe
4 is immovable with respect to the camera body, so that when the correction optical system d1 moves, the position of the center of gravity of light on the light receiving unit e5 also moves. As a result, the output current I from PSDe4
Since the ratio between 1 and I2 changes, the position of the correction optical system d1 can be detected by measuring this ratio.

The slit e3 is configured such that the light emitting LED side is wide and the light receiving PSD side is narrow, thereby sharpening the directivity while suppressing energy loss.
Further, since the slit e3 is provided to extend in a direction orthogonal to the moving direction (arrow e7) to be detected, in the example of FIG. 4, the slit e3 is sensitive to the movement of the correction optical system d1 in the direction of arrow e7, It is not affected by movement in the direction perpendicular to it. Two such position detection mechanisms are independently provided for detecting the X-direction position and the Y-direction position of the correction optical system d1. As described above, in the illustrated embodiment, the light emitting LED and the light receiving PSD constitute a current position detecting unit.

Next, the drive control unit a23 in FIG.
This will be described in detail with reference to FIGS. FIG. 5 shows a schematic configuration of the drive control unit a23. This part can be roughly divided into data receiving units (b1 to b4), DA
Converter section b5, X-direction servo control section (b6, b8),
It comprises a Y-direction servo control section (b7, b9) and an actuator driver section b10.

B1 and b2 are target position data receiving sections for receiving and storing target position signals from the target position calculating section a9 in the X direction and the Y direction, respectively.
b3 and b4 are gain data receiving units that receive and store signals from the drive correction unit a11 in the X direction and the Y direction, respectively. The gain of the servo circuit is set based on the gain data stored here. Hereinafter, the servo control according to the present invention will be described.

When the X direction is selected by an X / Y direction selection circuit (not shown), target position data in the X direction is stored in the data receiving unit b1 from the target position calculating unit a9. This data is D / A converted by the DA converter b5. At this time, the sample and hold circuit b6 enters a sampling state, and the output from b5 is output to the X-direction servo control circuit b8 as a target position voltage. On the other hand, the sample hold circuit b7 is in a hold state.

At the next timing, in order to set a target position in the Y direction, the Y / Y direction is selected by the X / Y direction selection circuit, and the output from b5 is set as the target position voltage in the same manner as described above. Output to the direction servo control circuit b9. In the same manner, the output of the target data in the X direction and the Y direction is alternately repeated.

Since the X-direction servo control circuit b8 and the Y-direction servo control circuit b9 have the same configuration, only the X-direction servo control circuit b8 will be described. As shown in FIG. 5, the X-direction servo control circuit b8 includes a servo control unit and a position detection unit. The servo control is shown in detail within the dashed line in FIG. 6 and will be described.

As described above, the sample and hold circuit b
6, a voltage Vt corresponding to the target position is input. On the other hand, X
The voltage corresponding to the current position in the direction is generated by the position detection unit as follows. P received light from LEDe1
The currents I1 and I2 output from SDe4 are I / V
Conversion circuits (current / voltage conversion circuits) c23 and c24 convert the respective voltages into voltages. The converted voltage value is subtracted by the subtraction circuit c25 and added by the addition circuit c26. Adder circuit c
The voltage value obtained at 26 is sent to the current control unit c27. Here, control is performed to keep the sum of the voltage values constant. If the sum of the voltage values is kept constant, the output of the subtraction circuit c25 can be monitored to detect the position of the correction optical system d1. The output from the subtraction circuit c25 is passed through a low-pass filter c28 to remove high-frequency noise and output a voltage Vn corresponding to the current position of the correction optical system d1 in the X direction. The signal from the low-pass filter c28 is added to the addition circuit c
3 and at the time of the offset error measurement described later, it is also sent to the actual drive position capturing section a14 (see FIG. 1) on the camera body side.

The adder c3 subtracts the target position equivalent voltage Vt from the current position equivalent voltage Vn. Since the current position equivalent voltage Vn has a negative value, it can be subtracted by adding it with an adder circuit. The proportional gain circuit c4 sets the gain of the difference between the target position and the current position. The differentiating circuits c5 and c6 perform 90 ° phase lead compensation, and can perform 180 ° phase lead compensation by performing the differentiation twice. If all the circuits c4 to c6 are used, PDD control referred to in control theory can be performed. By combining these circuits, various gains corresponding to the gain data set value in the X-direction gain unit b3 can be obtained. That is, even if there is a solid variation in the driving mechanism, it can be absorbed. In addition, these circuits can also correct the effect of a temperature change.

The servo offset circuit c8 includes c4 to c6
By adding an offset voltage, which will be described in detail later, to the final gain obtained through each of the circuits described above, the SMA is prevented from becoming slightly heated, thereby stabilizing the servo drive characteristics. The circuit c7 performs final voltage gain conversion and removal of high frequency noise. The reference voltage part c9 is
The reference voltage is output to the actuator driver b10. The actuator driver b10 applies a voltage proportional to the input voltage to the SMAd17. However, in the present invention, as described later, when the value of Vin−Vref becomes negative,
No voltage is applied to the SMA.

FIG. 7 shows the connection state of the driver IC in the actuator driver b10, and FIG. 8 shows its output characteristics. The Vin terminal f2 receives an input from the circuit c7 in FIG. The Vref terminal f3 receives an input from the reference voltage unit c9 in FIG. By comparing the “input value from the Vin terminal f2” with the “input value from the Vref terminal f3”,
When n−Vref is positive, the SM +
A driving voltage is applied to the SMAd17.
Contracts in the direction in which the bias spring d18 is extended. On the other hand, V
Since the M- terminal f5 is not connected to the outside, Vin-
When Vref is negative, no voltage is applied to SMAd17. In this case, the SMAd17 is extended by the spring force of the bias spring d18. As described above, the output of the actuator driver IC is proportional to Vin-Vref when it is positive, and becomes zero when Vin-Vref is negative. This is shown in the graph of FIG.

As another method for obtaining the same effect, when the signal value from the circuit c7 is higher than Vref, the voltage value is directly used as the actuator driver b.
The output to the actuator driver b10 is stopped in the opposite case, or the actuator driver is controlled to stop at GND when Vin-Vref is negative. A circuit in the driver IC in b10 may be configured. In either case, the present invention restricts the final output to the actuator driver b10 as described above.

As described above, in the present invention, the terminal of the linear output driver IC is connected to only one end of
Since the voltage is applied only when -Vref is positive, the circuit configuration of the driver IC can be simplified. On the other hand, a case will be described in which a conventionally used motor is used although the actuator becomes large in size. FIGS. 9 and 10 show the connection relationship between the driver IC and the motor when the VM + terminal f4 and the VM- terminal f5 are both connected to the motor to drive the correction optical system d1. FIG. 9 and FIG. 10 show the connection state and output characteristics of the driver IC in such a case. In FIG. 9, unlike the present invention, the VM-terminal f5 is a motor f6 which is an actuator.
It can be seen that it is connected to. Also, from FIG. 10, Vin
It can be seen that even when −Vref is negative, there is an output from the VM− terminal f5. When the motor is replaced with the SMA and the connection shown in FIG. 9 is made, even if it is desired to drive in the direction in which the spring contracts, the drive is performed in the direction in which the SMA contracts, and correct driving cannot be performed. The present invention can be clearly understood by comparing with such an example. In the present invention, even a general-purpose driver IC used in the case of FIGS. 9 and 10 can be used simply by not connecting to the VM-terminal f5. . Further, a positive output linear driver circuit having the output characteristics shown in FIG. 8 may be created and used.

In the actuator using a shape memory alloy and a bias spring according to the present invention, when a voltage is applied to the shape memory alloy, “current” → “heat generation” → “tensile force” → “acceleration” → “speed” → The position of the driven member is controlled according to the principle of “position”. Where "current"
→ In the three processes of “heat generation”, “acceleration” → “velocity”, “velocity” → “position”, there is a phase delay of 90 ° each, so a total of third-order (270 °) phase delay occurs It will be. Using the servo circuit shown in FIG.
The effect of performing DD (proportional + differential + differential) control
This will be described with reference to a Bode diagram.

FIG. 11 shows the result of actually preparing an actuator model using a shape memory alloy and a bias spring, and actually measuring the frequency response of this model. Looking at the measurement results, when the frequency is higher than 70 Hz, a phase delay of about 270 ° occurs. As a result, when servo control is performed, the primary
It can be predicted that resonance will occur only with phase lead compensation (differential) of (90 °). In order to suppress this resonance, it is necessary to use differential control.
Since the phase can only be advanced by 90 °, in the case of FIG. 11, in order to make the phase delay sufficiently smaller than 180 °, one differentiation is not enough and two differentiations are required. Can be predicted. The correctness of this prediction will be verified with FIGS. 12 and 13.

FIG. 12A shows open characteristics (characteristics without feedback) when PD (proportional + differential) control is performed on the actuator model shown in FIG.
FIG. 12A shows that there is no phase margin or gain margin. When feedback control is performed for this, FIG.
As shown in (b), resonance occurs at a frequency slightly lower than 1 KHz. That is, it can be seen that good control characteristics cannot be obtained only by phase compensation for 90 °.

On the other hand, FIG. 13A shows the open characteristic when PDD control (proportional + differential + differential) is performed. Unlike the case of FIG. 12A, a phase margin and a gain margin are obtained. FIG. 13 (b) shows the frequency response when feedback control is performed on this, but the resonance as shown in FIG. 12 (b) does not occur.

Next, the effect of providing the servo offset circuit c8 will be described with reference to FIG. Fig. 14
As shown in the figure, the larger the set value of the gain, the larger the average current (average applied current) applied in a predetermined time corresponding to the constant deviation from the target position (naturally, the larger the average applied voltage also becomes) ). That is, when an actuator is formed using a shape memory alloy, there is a problem that servo control becomes unstable due to the shape memory alloy becoming slightly heated. Thus, in the present invention, this problem is solved by using an offset voltage. That is, by adding a negative “offset voltage” to the final gain obtained through the proportional gain circuit c4 and the differential gain circuits c5 and c6 shown in FIG. 6, the “average voltage value applied to the shape memory alloy” is obtained. Is smaller than the “average voltage value obtained by the PDD calculation”. Thereby, the shape memory alloy can be suppressed from being overheated. When performing servo control using an actuator composed of a shape memory alloy and a bias spring, improve the servo drive performance
If the gain is increased to reduce the error between the target position and the actual position, the average applied voltage also increases, and the average temperature also increases. As a result, the driving state becomes unstable and the position offset error also changes (when the gain is increased, the instability increases and the average driving position shifts in the direction in which the shape memory alloy shrinks). In order to perform optimal drive control with such an actuator system, it is desirable to lead to an optimal control state by the following configuration and procedure. (1) “Proportional and differential gains” and “offset voltage”
Thus, the control state is set to a stable state with less vibration. At this point, a “position offset error” remains. (2) The remaining "position offset error" is detected and stored in the camera, and the position is controlled by taking the offset error into consideration in advance.

FIGS. 15 and 16 show that control characteristics are stabilized by adding an offset voltage. Figure
15 shows the case where the gain is “medium”, and FIG. 16 shows the case where the gain is “large”. FIG. 15 (a) and FIG.
(b) shows the driven member for the same target position (curve A)
(In this example, the actual driving result of the correction optical system)
The case where the offset voltage is not applied and the case where the offset voltage is added are shown. As can be seen by comparing the curves B in FIGS. 15A and 15B, the vibration of the curve B is suppressed by adding the offset voltage. That is, the vibration of the driven member is suppressed, and the driving characteristics by the servo control are stable. FIG. 16 shows the case where the gain is large, but it can be seen that the drive characteristics by the servo control are stable as in the case of FIG.

In FIGS. 15 (b) and 16 (b), the distance between the curves A and B indicates the position error (ie, “position offset error”) remaining after the application of the offset voltage. . In FIGS. 15 and 16, the curve B (drive result position) is changed to the curve A by adding an offset voltage.
Although it is approaching the (target position), the curve B may move away from the curve A by adding an offset voltage depending on the target position. Specifically, when the drive result position where no offset voltage is applied is on the side where the shape memory alloy extends, the curve B moves away from the curve A by applying a negative offset voltage. Conversely, when the driving result position is on the shrinking side of the shape memory alloy, the curve B approaches the curve A by applying a negative offset voltage. This is because the offset voltage is always a negative voltage, and the addition of this voltage causes the shape memory alloy to "heat slightly and shrink excessively."
Is prevented.

The specific value of the offset voltage is determined by observing the actual drive of the actuator when a pseudo camera shake is given in the final stage of the camera manufacturing process. Further, an offset error remaining after the application of such an offset voltage is also actually measured and stored in the camera. That is, the “offset voltage value” and the “offset error” are unique values for each product. This procedure will be described with reference to the flowchart in FIG.

A sine wave of a predetermined parameter is given to the camera as a pseudo camera shake. Then, the actual drive position of the correction optical system driven to correct the camera shake is determined by a position detection unit.
Adjust the proportional gain, differential gain and twice differential gain while monitoring with the output of (Fig. 5) (fa1 → fa2 → fa
3). The gain is adjusted by changing the resistance of each of the circuits c4 to c6 (see FIG. 6). After adjusting each gain, the offset voltage is adjusted (fa4). The value of the offset voltage is set to suppress the shape memory alloy from becoming slightly heated, and always has a negative value. That is, the voltage applied to the shape memory alloy is suppressed. Until driving stability is within the desired range, fa1 to fa4
When the adjustment is repeated and the value falls within the range, it is determined that the drive control state has been optimized, and the process proceeds to steps after fa5. In other words, a control state with high drive stability is first achieved in steps fa1 to fa5, and in a subsequent step, an offset error caused by applying an offset voltage is actually measured.

In the measurement of the offset error, a sine wave of a predetermined parameter is given to the camera as a pseudo camera shake. The target position calculation unit a9 calculates (sets) a target position Pt (t) of the driven member necessary to cancel the camera shake,
This is output to the servo control circuit at 1 ms intervals (fa6 →
fa7). Correspondingly, the actual drive position Pn (t) after the driven member is actually driven is detected by the position detection unit and is taken into the actual drive position acquisition unit a14 (see FIG. 1).
(fa8). Calculation of target position Pt (t) and actual drive position Pn
(t) is continuously detected for 2 seconds. Calculation of target position is 1
ms, the target position Pt in 2 seconds
The calculation of (t) and the detection of the actual drive position Pn (t) are performed in
This is performed 00 times (fa7 → fa8 → fa9). Target position Pt
By subtracting the actual drive position Pn (t) from (t), a position control error can be obtained. The average value of the error for 2000 times is calculated and stored as an “offset error” in the target position correction unit a10 (see FIG. 1) of the camera (fa10 → fa1).
1). The actual measurement of gain adjustment and offset error
Performed separately in the X and Y directions. Note that the actual measurement of the offset error needs to be performed after performing the gain adjustment and the offset voltage adjustment.

As described above, since the offset error unique to each product is stored in the camera itself, the offset error is canceled by subtracting the offset error from the target position calculated by the target position calculator a9. be able to. FIG. 18 shows the relationship between the target position and the actual drive position when performing servo control in consideration of the offset error stored in the camera itself. It can be seen that the offset errors appearing in FIG. 15 (b) and FIG. 16 (b) have been eliminated, and position control with almost no error has been achieved. It should be noted that the actual target position calculation is performed together with a temperature correction or the like that takes into account not only the offset error but also a temperature change.

In the above example, the optimization including the setting of the gain and the setting of the offset voltage of each circuit is performed in the optimization process of fa1 to fa5. However, the present invention is also applicable to the servo control without applying the offset voltage. It is possible to apply the adjustment method.

FIG. 19 shows another example of the servo circuit shown in FIG. In the servo circuit shown in FIG.
4. The differential gain circuits c5 and c6 are included, and PDD control can be realized as described above. On the contrary,
The servo circuit of FIG. 19 employs an integral gain circuit c105 instead of the differential gain circuit c5 in FIG.
Control can be realized. The PID control is effective in a control system in which the driven member slowly moves at a low frequency when it is desired to increase the stop position control of the driven member. The gain adjustment, the offset voltage adjustment, and the actual measurement of the offset error can be performed in the same manner as described above.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a system configuration of a camera shake correction camera according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a driving mechanism of a correction optical system used in the camera of FIG.

FIG. 3 is a graph showing operating characteristics of a shape memory alloy used in the drive mechanism of FIG.

4 is a schematic diagram illustrating the principle of detecting the position of a correction optical system in the drive mechanism of FIG.

FIG. 5 is a diagram illustrating a configuration of a drive control unit in the system of FIG. 1;

6 is a diagram showing a circuit configuration in a servo control unit shown in FIG.

FIG. 7 is a diagram illustrating a driver IC in the actuator driver shown in FIG. 6;

FIG. 8 is a graph showing output characteristics of the driver IC of FIG.

FIG. 9 is a diagram illustrating an example in which a motor is used as an actuator.

FIG. 10 is a graph showing output characteristics of the driver IC.

FIG. 11 is a Bode diagram showing a result of producing an actuator model using a shape memory alloy and a bias spring and actually measuring a frequency response of the model.

FIG. 12 is a Bode diagram showing open characteristics and feedback characteristics when PD control is performed on the model of FIG. 11;

FIG. 13 is a Bode diagram showing open characteristics and feedback characteristics when PDD control is performed on the model of FIG. 11;

FIG. 14 is a graph showing a relationship between a magnitude of a set gain and an applied current.

FIG. 15 is a graph illustrating that drive characteristics are stabilized by applying an offset voltage.

FIG. 16 is a graph illustrating that drive characteristics are stabilized by adding an offset voltage.

FIG. 17 is a flowchart illustrating a procedure of gain adjustment, offset voltage adjustment, and offset error measurement in the present invention.

FIG. 18 is a graph illustrating an effect of correcting an offset error.

FIG. 19 is a diagram showing a configuration of a servo circuit that performs PID control.

[Explanation of symbols]

 d1 Correcting optical system d2 Holding frame d3 Guide rod d4 Slide guide d5 Terminal d6 Guide rod d7 SMA for Y direction d8 Bias spring for Y direction d9 Base d13 Guide rod d14 Slide guide d15 Terminal d16 Guide rod d17 SMA d18 for X direction Direction bias spring d19 Moving table e1 LED e2 Light emitting chip e3 Slit e4 PSD e5 Light receiving unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeru Wada 2-3-1-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Inventor Akira Kosaka Azuchi-cho, Chuo-ku, Osaka-shi, Osaka No. 2-313 Osaka International Building Minolta Co., Ltd. F-term (reference) 5C022 AA11 AB55 AC78 5H303 AA30 BB02 BB07 CC02 CC03 DD15 DD22 FF04 GG12 GG27 JJ04 JJ08 KK02 KK04

Claims (3)

[Claims] 1. An actuator comprising: a shape memory alloy whose shape is stored in a predetermined size; and an urging means for changing a size by applying an external force to the shape memory alloy, wherein the shape memory alloy has a memory size. The actuator controls the position of the driven member in the first direction in which the driven member returns to the first direction and the second direction in which the urging means changes the dimension of the shape memory alloy, and determines the target position where the driven member should be moved. Servo control adjustment in a control device including target position determining means, current position detecting means for detecting the current position of the driven member, and a servo control circuit for performing servo control based on the information on the target position and the current position. An optimization step of optimizing a gain setting of a servo control circuit within a predetermined allowable range, and an actual driving position of a driven member after the optimization, Servo control, comprising: an actual measurement step of actually detecting a difference between the actual drive position and the target position, and a storage step of storing the actually measured difference in the control device itself. Adjustment method. 2. The servo control circuit according to claim 1, wherein the servo control circuit includes a correction circuit for performing a correction for suppressing heating of the shape memory alloy in order to stabilize the drive control of the actuator. The optimization is performed including the following.
The described servo control adjustment method. 3. The servo control adjustment method according to claim 1, wherein said urging means is constituted by a spring.