JPH087363B2 - Shutter servo control device - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

 The present invention relates to a shutter servo control device.

[Prior art and its problems]

There is a demand to apply servo control to a shutter drive device in order to perform accurate exposure control or to obtain an arbitrary exposure time and aperture value. FIG. 9 is a block diagram of a general reference position tracking type servo control circuit. 1 is a reference signal generation circuit, 2 is a servo amplifier, 3 is a servo motor, and 4 is a blade position detection circuit. The reference signal generation circuit 1 generates a voltage indicating the reference position of the target shutter blade, and the servo amplifier 2 determines the difference (that is, position deviation) between the output of this reference signal generation circuit 1 and the output of the blade position detection circuit 4. Correspondingly, the servo motor 3 is driven. Then, since the servo blade 3 causes the shutter blade to be controlled to travel, the current position of the shutter blade follows the output level of the reference signal generating circuit 1. Therefore, by controlling the output level of the reference signal generating circuit 1 with the lapse of time, it is possible to freely control the opening F value, the opening rising time, the closing falling time and the like. However, when the shutter blade is driven using such a servo system, in order to ideally follow the output of the reference signal generating circuit 1 with the current position of the shutter blade, the shutter blade and its opening mechanism are included. It is necessary that the capacity of the drive circuit side is sufficiently large compared to the inertial force of the driven member, but in an actual still camera,
The power supply capacity is as low as a few volts, and only a small motor can be used due to restrictions on the layout space. Also, the shutter mechanism is required to respond instantly due to its nature. Under the present circumstances, it is difficult to limit the disturbance of the control characteristics to a practically sufficient range, and it is extremely difficult to adopt the servo system as the drive mechanism of the shutter blades.

[Means for solving problems]

The present invention has been made in view of such a current situation,
It is an object of the present invention to provide a shutter servo control device having practically sufficient control characteristics. In order to achieve the above object, the servo control device for a shutter of the present invention is as follows: On the premise of a servo control device for a shutter, which performs a shutter blade opening operation, an F value maintaining operation and a closing operation by a servo actuator: , A reference position signal generating circuit that sequentially generates a reference position signal that indicates the traveling position of the shutter blade during the F value maintaining operation and the closing operation, and a current position signal that indicates the actual position of the shutter blade A position signal generation circuit: a reference speed signal generation circuit that generates a reference speed signal that indicates the operating speed of the servo actuator; and a current speed signal generation circuit that generates a current speed signal that indicates the actual speed of the servo actuator: A position deviation calculating circuit for calculating a position deviation which is a deviation between the reference position signal and the current position signal; A speed deviation calculating circuit for calculating a speed deviation, which is a deviation between the speed signal and the current speed signal, and a driving means for driving the servo actuator by an addition signal of the position deviation and the speed deviation, respectively, and: The reference speed signal generation circuit is configured to generate a different reference speed signal for each of the opening operation, the F value maintaining operation, and the closing operation of the shutter blade. Further, it is desirable that the shutter servo control device of the present invention is based on the above premise: the reference position signal and the reference speed signal at the time of the opening operation and the closing operation of the shutter blade are made to have an inverted similar shape. ing. Further, preferably, the servo control device for a shutter of the present invention is based on the above premise that the absolute value of the operating speed of the servo actuator during the opening operation and the closing operation of the shutter blade is substantially constant. The reference position signal and the reference speed signal are controlled.

[Action]

That is, the shutter servo control device of the present invention basically operates so that the current position signal follows the reference position signal and the current speed signal follows the reference speed signal.
The feature is that the reference speed signal is controlled corresponding to the opening operation of the shutter blade, the F value maintaining operation and the closing operation, and the servo actuator is driven by the added signal of the position deviation and the speed deviation. It Therefore, for example, when the position deviation swings to the plus side, the servo actuator is basically driven in the direction of decreasing the position deviation, but the current speed signal is changed in accordance with the driving in the direction of decreasing the position deviation. The speed deviation exceeds the reference speed signal and the speed deviation swings to the negative side. Therefore, since the plus (minus) component of the position deviation is canceled by the minus (plus) component of the speed deviation, overshooting in the vicinity of the position deviation converging to 0 is suppressed, and the overshoot is over the entire control region. It is possible to reduce the amplitude of, and it is possible to perform servo control with good followability. Further, when the reference position signal and the reference velocity signal at the time of opening and closing of the shutter blade are made to have an inverted similar shape, the inertial force of the shutter opening / closing mechanism including the actuator is set at the time of opening and closing of the shutter blade. Since it is possible to make them almost the same, it becomes easy to adjust various coefficients on the circuit and mechanical members, and further, the absolute speed of the servo actuator during opening and closing of the shutter blade When the reference position signal and the reference speed signal are controlled so that the value becomes a substantially constant speed, the inertial force of the shutter opening / closing mechanism including the actuator is substantially reduced at any time of opening operation and closing operation of the shutter blade. Since it is possible to keep constant, it becomes easier to adjust various coefficients on the circuit and mechanical members.

【Example】

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. First, FIG. 1 is a view of a shutter mechanism to which the present invention is applied, as seen from the side of a taking lens. In the figure, 10 is a shutter base plate, 11 is a sector ring, and the sector ring 11 is supported so as to rotate at a constant angle on an arc centered on the aperture center P ₁ . Further, 12 is a servo motor capable of controlling the rotation direction, rotation position, and rotation angular velocity, and the output pin 12a of the servo motor 12
Moves a fixed angle on an arc centered on the motor center P ₂ . In this embodiment, the output pin of the servo motor 12
The servo motor 12 stops at that position when no voltage is applied to the servomotor 12, moves to the left in the drawing when a positive voltage is applied, and moves to the right in the drawing when a negative voltage is applied. The moving speed is determined by the absolute value of the applied voltage. A lever 11d formed so as to project from the sector ring 11 is engaged with the output pin 12a. Further, 13 is a shutter blade, which is rotatably supported by a shaft 10a on the shutter base plate 10, and a sector ring 11 is formed in a long hole 13a formed in the shutter blade 13.
The sector pin 11a formed so as to project upward is engaged. Therefore, the state shown in the figure is the initial state and the servo motor
Sector ring 11 by applying a positive voltage to 12
When the shutter blade 13 is rotated in the direction of arrow A, the shutter blade 13 rotates counterclockwise about the shaft 10a while the elongated hole 13a is engaged with the sector pin 11a. Although not shown in FIG. 1, the shutter blades are also attached to the shafts 10b and 10c on the shutter base plate 10.
A shutter blade having at least the same blade portion as that of 13 is rotatably supported, and two shutter blades (not shown) are engaged with the sector pins 11b and 11c and swing like the shutter blade 13, respectively. Therefore, when the sector ring 11 is rotated in the direction of arrow A as described above, the axis 10b
・ Two shutter blades (not shown) supported by 10c also rotate counterclockwise about the axes 10b and 10c, respectively.
e starts opening. (Shutter opening operation) When the applied voltage to the servo motor 12 is set to 0V in the state where the aperture 11d is opened in this way, the servo motor 12, the sector ring 11 and the shutter blade 13 stop at that position. , The aperture 11e maintains a constant F value. (F value maintaining operation) Further, when the sector ring 11 is rotated in the direction of arrow B by applying a negative voltage to the servo motor 12 in the open state, the shutter blades 13 rotate right about the shaft 10a, Also, since the two shutter blades (not shown) supported by the shafts 10b and 10c also rotate clockwise about the shafts 10b and 10c, respectively.
The aperture 11e is closed and the exposure operation ends.
(Shutter closing operation) Next, 14 is a sub-aperture for detecting the blade position,
A light-emitting element is arranged on the front side of the sub-aperture 14, and a light-receiving element is arranged on the back side of the sub-aperture 14. The sub-aperture 14 is arranged when the shutter blade 13 is rotated to the left (that is,
It is adapted to be shielded by a shield portion 13b formed on the shutter blade 13 (when performing an exposure operation). In this way, the opening area of the sub-aperture 14 varies depending on the position of the shutter blade 13, so that the current position of the shutter blade 13 can be detected by the amount of light incident on the light receiving element. Although not shown in FIG. 1, the servo motor 12 is provided with a speed detection circuit including a generator for detecting the rotation speed. As described above, the shutter mechanism of the present embodiment is configured to perform one exposure operation by three types of operations: (1) shutter opening operation, (2) F value maintaining operation, and (3) shutter closing operation. The current position of the shutter blade 13 and the rotation speed of the servo motor 12 are detected. The shutter servo control device of the present invention is a system that simultaneously performs a position servo that causes the current position of the shutter blade 13 to follow the reference position signal and a speed servo that causes the rotation speed of the servo motor 12 to follow the reference speed signal. The characteristic feature of the present invention resides in that an appropriate reference speed signal is applied during the three types of operations during the shutter opening operation, the F value maintaining operation, and the shutter closing operation. Further, in particular, a characteristic point in this embodiment is that (1) the absolute values of the amounts of change of the reference position signals during the shutter opening operation and the shutter closing operation are made equal and the directions thereof are reversed. (2) The reference position signal / reference speed signal and the shutter blade opening mechanism are configured so that the rotation speed of the servo motor 12 becomes substantially constant during the shutter opening operation and the shutter closing operation. FIG. 2 is a block diagram showing an example of a servo control circuit which performs such control operation. In FIG. 2, 15 is the reference position signal V of the shutter blade 13.
_This is a reference position signal generation circuit for generating _S , and the reference position signal generation circuit 15 generates a reference position signal V _S as shown in FIG. ₃ according to the timing control signals S _{1 to} S ₃ given from the sequence circuit 16. . The timing control signal S ₁ is a signal that gives the start timing of the shutter opening operation, and the timing control signal S ₂
Is a signal that gives the start timing of the F value maintaining operation,
The timing control signal S ₃ is a signal that gives the start timing of the shutter closing operation. FIG. 4 is a circuit diagram showing a concrete example of the reference position signal generating circuit 15 in principle. I ₁ , I ₂ , I ₃ , I ₄ , I ₅ , I ₆ are constant current sources which are appropriately weighted. Yes, constant current source I ₁ and constant current source
The current value of I _{4 is the same,} the current values of the constant current source I ₂ and the constant current source I ₅ are the same, and the current values of the constant current source I ₃ and the constant current source I ₆ are the same.
15a is a timer decoder consisting of a timer and a decoder, and 15b
Is a capacitor, 15c is a buffer, SW ₁ , SW ₂ , SW ₃ , SW ₄ , SW ₅
・ SW ₆ indicates each current switch. Each current switch SW ₁
SW ₂ , SW ₃ , SW ₄ , SW _5, and SW ₆ are operated by the output of the timer decoder 15a, and their operation timings are shown in the time chart of FIG. First, when the timing control signal S ₁ is applied, the timer decoder 15a sequentially makes the current switches SW ₁ , SW _2, and SW ₃ , so that the currents flowing through the constant current sources I ₁ , I _2, and I ₃ are sequentially added. The added current charges the capacitor 15b. Therefore, the reference position signal V output from the buffer 15c
_S rises to polygonal line as shown in Figure 3 after the occurrence of the timing control signal S _1. Further, when the timing control signal S ₂ is applied, the timer decoder 15a to break the full current switch SW ₁ to SW _6.
Therefore, the capacitor 15b is neither charged nor discharged, and therefore the reference position signal V _S maintains a constant value as shown in FIG. 3 after the timing control signal S ₂ is generated. Furthermore, when the timing control signal S ₃ is applied, the timer decoder 15a is sequentially break the current switch _{SW 6 · SW 5 · SW 4} , the capacitor 15b is discharged by the current flowing through the constant current source I ₆ · I ₅ · I ₄ To be done. Therefore, the reference position signal V _S drops in a polygonal line shape as shown in FIG. 3 after the timing control signal S ₃ is generated. The reference position signal V _S, which is the output of the reference position signal generating circuit 15, is added to one input of the servo amplifier 17. The reason why the reference position signal V _S is raised and lowered in a polygonal line shape as described above is as follows. That is, in order to obtain stable control characteristics, the servo motor
It is desirable to move the movable mechanism including 12, the sector ring 11, and the shutter blade 13 with a constant inertial force, and for that purpose, it is necessary to rotate the servo motor 12 at a constant speed. In this embodiment, the current position of the shutter blade 13 is optically detected by the blade position detection circuit 20 via the sub-aperture 14. However, the blade position detection circuit 20 when the servo motor 12 is rotated at a constant speed is used. Output does not always increase and decrease linearly, but varies depending on the characteristics of the blade position detection circuit 20 itself, the shape of the sub-aperture 14, the shape of the shielding portion 13b formed on the shutter blade 13, and the like. The present embodiment assumes a case where the output of the blade position detection circuit 20 increases or decreases in a polygonal line when the servo motor 12 is rotated at a constant speed, and the increase / decrease characteristic of the reference position signal V _S is The increase / decrease characteristic of the output of the blade position detection circuit 20 when the servo motor 12 is rotated at a constant speed is determined as a reference. If the output of the blade position detection circuit 20 increases / decreases linearly when the servo motor 12 is rotated at a constant speed, the reference position signal V _S may simply be linearly increased / decreased. If the output of the blade position detection circuit 20 increases or decreases exponentially when the servo motor 12 is rotated at a constant speed, the reference position signal V _S may be exponentially increased or decreased. Good. Next, 18 and 19 are a light emitting element 18 and a light receiving element 19 provided on both sides of the sub-aperture 14 formed on the shutter blade 13 described above, and the current position of the shutter blade 13 is the output of the light receiving element 19. To be detected. The detection output of the light receiving element 19 is converted into a current position signal V _M which is a voltage signal by the blade position detection circuit 20 and added to the other input of the servo amplifier 17, and the servo amplifier 17 basically receives the reference position signal V _S. And the drive voltage V _OUT for the servo motor 12 is controlled based on the deviation of the current position signal V _M. In this embodiment, the output of the blade position detection circuit 20 is also added to the sequence circuit 16, which is used to determine the strobe tuning timing. Next, in FIG. 2, reference numeral 21 is a speed detection circuit having a generator G for detecting the rotation speed of the servo motor 12, and the speed detector circuit 21 outputs a current speed signal V _G indicating the rotation speed of the servo motor 12. It is added to one input of the speed deviation calculation unit 22. Then, the speed deviation calculation unit 22 receives the reference speed signal and the current speed signal V _G added from the reference speed signal generation circuit 23.
Is calculated (that is, the speed deviation), and the output of the servo amplifier 17 is corrected. In this embodiment, the generator G is the servo motor 12
Generates a negative voltage when it rotates in the opening direction, and generates a positive voltage when the servomotor 12 rotates in the closing direction. That is, in this embodiment, the sign of the velocity component is treated as a minus on the circuit. Next, FIG. 5 is a more specific circuit diagram of this embodiment.
The elements shown in FIG. 2 are designated by the same reference numerals as those in FIG. In FIG. 5, A _{1 to} A ₈ are composed of operational amplifiers, and 25 is a bias power supply circuit for generating a bias voltage V _B. First, the operational amplifier A ₁ uses the reference position signal V _S and the current position signal.
It is for calculating the deviation of the V _M, the output V ₁ of the operational amplifier A ₁ is applied to the inverting input of the operational amplifier A _2. Operational amplifier A ₂ is for inverting the positional deviation which is the output of the operational amplifier A _1, the output of the operational amplifier A ₂ is an operational amplifier A ₃
Is added to the negative phase input of the servo amplifier 12, and the operational amplifier A ₃ adds the speed deviation described below to the position deviation described above to drive the servo motor 12.
Control V _OUT . The operational amplifier A ₂ is provided to adjust the sign of the positional deviation because the positional deviation output from the operational amplifier A ₁ is added to the negative phase input of the operational amplifier A ₃ . The output of operational amplifier A ₃ is the negative phase input of operational amplifier A ₄ and the operational amplifier.
Applied to the positive phase input A _5, the potential difference between the output V ₅ output V ₄ and the operational amplifier A ₅ of the operational amplifier A ₄ is applied to the servo motor 12 as the drive voltage V _OUT. Next, a more specific circuit example of the reference speed signal generation circuit 23 will be described. The reference speed signal generation circuit 23 has buffers A ₆ and A ₇ , switching transistors Q ₁ and Q ₂ , constant current sources Ia and Ib, and a resistor R ₀ . First, the bias power supply circuit 25 is connected to the positive-phase input of buffer A _6.
Bias voltage V _B is added to the output, and the bias voltage V _B is directly introduced to the output. The output of buffer A ₆ is applied to the positive phase input of buffer A ₇ via resistor R ₀ ,
Voltage generated across the resistor R ₀ in accordance with the state of the transistor Q ₁ · Q ₂ in this case switching is superimposed on the output of buffer A ₆ is applied to the positive phase input buffer A _7, the buffer A ₇ Becomes the reference speed signal V ₇ . Now, to generate an appropriate reference speed signal when three types of operations in · F value maintained during shutter closing operation operates the shutter opening operation in the present embodiment is as described above, the reference speed signal V ₇ The value is switched by the timing control signals S ₅ and S ₆ . The switching timing of the timing control signals S ₅ and S ₆ is shown in the time chart of FIG. As described above, in the present embodiment, the sign of the speed component is treated as a minus in the circuit, so the reference speed signal generation circuit 23
Considering the reference speed signal during the F value maintaining operation as the center point, generates a negative reference speed signal during shutter opening operation and a positive speed signal during shutter closing operation. That is, during the shutter opening operation, if the timing control signals S ₅ and S ₆ are both set to H level, only the transistor Q ₂ is turned on and the current flows from the resistor R ₀ to the constant current source Ib.
The positive phase input level of the buffer A ₇ is lower than the output level of the buffer A ₆ by the voltage generated across the resistor R ₀ , and this is output as the reference speed signal V ₇ . Also, if only the timing control signal S ₅ is set to H level during the F value maintaining operation, no current will flow through the resistor R ₀ .
The positive phase input level of the buffer A ₇ becomes equal to the output level of the buffer A ₆ , and this is output as the reference speed signal V ₇ . Moreover, only the transistor Q ₁ when the both L level timing control signal S ₅ · S ₆ during shutter closing operation is turned on, current flows through the resistor R ₀ from the constant current source Ia, positive phase of buffer A ₇ The input level rises above the output level of the buffer A ₆ by the voltage generated across the resistor R ₀ , and this is output as the reference speed signal V ₇ . In this embodiment, the current values of the constant current sources Ia and Ib are set equal, and the reference speed signal V ₇ during the shutter opening operation is (Equation -1), and the reference speed signal V during the F value maintaining operation is ₇ is (expression −
In 2), the reference speed signal V ₇ during the shutter closing operation is (equation −
The values shown in 3) are obtained. V ₇ = V _B -k (Formula -1) V ₇ = V _B (formula _{-2) V 7 = V B +} k ( Equation -3) Here, k R ₀ × Ia and R ₀ × Ib reference speed signal V ₇ is added to the positive phase input of the operational amplifier A ₈ which constitutes the speed deviation calculation circuit 22, and the current speed detection generator G is connected between the negative phase input side resistance of the operational amplifier A ₈ and the positive phase input. There is. Then, the speed deviation signal V ₈ output from the speed deviation calculation circuit 22 is added to the positive phase input of the operational amplifier A ₃ and reflected in the drive voltage of the servo motor 12. Next, the operation of the present embodiment will be described by dividing it into three types of operations during shutter opening operation, F value maintaining operation, and shutter closing operation. First, the opening operation of the shutter blades 13 is started when a shutter release signal SR is applied to the sequence circuit 16 by pressing a shutter button (not shown). The sequence circuit 16 raises the timing control signal S ₁ when the shutter release signal SR is added. The timing control signal S ₁ causes the reference position signal generation circuit 15 to generate a reference position signal V _S that rises in a polygonal line, and this reference position signal V _S is applied to the negative phase input of the operational amplifier A ₁ . Further, the blade position detection circuit 20 applies a blade position detection signal V _M inversely proportional to the opening area of the sub aperture 14 to the positive phase input of the operational amplifier A ₁ . Therefore, the operational amplifier A ₁ applies the output V ₁ shown in the following (Equation-4) to the negative phase input of the operational amplifier A ₂ . _{V 1 = V M + V B} -V S ( Equation -4) Also, since the positive phase input of the operational amplifier A ₂ is the bias voltage V _B being applied, the operational amplifier A ₂ is represented by the following equation (-5) Applied output V ₂ to the inverting input of op amp A ₃ . V ₂ = V _B −G ₂ (V _M −V _S ) (Equation -5) However, in (Equation -5), G ₂ is the gain of the operational amplifier A ₂ . Now, the speed deviation V ₈ are applied to the positive input of the operational amplifier A ₃ is the output of the bias voltage V _B and the operational amplifier A _8. Here, when the current speed which is the output of the generator G is V _G and the gain of the operational amplifier A ₈ is G ₈ , the speed deviation V ₈ is represented by the following (Equation-6). Since _{V 8 = V 7 -G 8 V} G ( Equation -6) operational amplifier A ₃ generates a value obtained by subtracting the negative phase input from the sum of the positive phase input, from (Equation -6) and (Equation -5) After calculating the output V ₃ of the operational amplifier a _3, the output V ₃ of the operational amplifier a ₃ is represented by (equation -7). V ₃ = V _B + V ₈ −V ₂ = V ₇ −G ₈ V _G −G ₂ (V _S −V _M ) (Equation 7) Further, the sequencer circuit 16 controls the timing control signals S ₅ and S ₆ when the shutter is open. Are both set to H level, and the current flows from the resistor R ₀ to the constant current source Ib, the reference speed signal V ₇ becomes the value shown in (Equation-1), and the reference speed signal in (Equation-7) is
Substituting the value of equation (-1) as V _7, the output V ₃ of the operational amplifier A ₃ is represented by (Equation -8). Together _{V 3 = V B -k-G} 8 V G -G 2 (V S -V M) output V ₃ (Formula -8) operational amplifier A ₃ is applied to the inverting input of the operational amplifier A _4, the operational amplifier A ₅ Is added to the positive phase input of. Further, since the bias voltage V _B is applied to the positive phase input of the operational amplifier A ₄ , its output V ₄ is shown by the following (Equation-9), and the negative phase input of the operational amplifier A ₅ is biased. Since the voltage V _B is applied, its output V ₅ is given by the following (Equation-10). _{V 4 = V B -G 4 (} V 3 -V B) = V B + G 4 (V B -V 3) ( Formula _{-9) V 5 = V 3 -G} 5 (V B -V 3) ( Formula - 10), however, shows a gain (equation -9) · (G ₄ and G ₅ are each operational amplifier a ₄ and a ₅ in formula 10). In this embodiment, since the output potential difference between the operational amplifiers A ₄ and A ₅ is applied as the drive voltage V _OUT for the servomotor 12, if the resistance value is adjusted so that the gain G ₅ becomes equal to the gain G ₄ , the servo The drive voltage V _OUT for the motor 12 has a value represented by the following (Equation-11). V _OUT = V ₄ −V ₅ = (1 + 2G ₄ ) (V _B −V ₃ ) (Equation −11) This (Equation −11) shows the output V ₃ of the operational amplifier A ₃ when the shutter is opened (Equation −8). Is substituted, the drive voltage V _OUT shown in the following (Equation-12) is applied to the servo motor 12. _{V OUT = (1 + 2G 4} ) · _{[(k + G 8 V G -G} 2 (V M -V S) ] =
(1 + 2G ₄ ) · [G ₂ (V _S −V _M ) − (− k−G ₈ V _G )] (Equation -12) As is apparent from (Equation -12), in the present embodiment, when the shutter opening operation is performed, When the current position signal V _M is smaller than the reference position signal V _S , the drive voltage V _OUT is positive, and when the current position signal V _M is larger than the reference position signal V _S , the drive voltage V _OUT is positive.
V _OUT becomes negative and the servo motor 12 is driven so that the current position signal follows the reference position signal. Since the reference position signal V _S increases linearly during shutter opening operation, the shutter blade 13 opens so that the current position signal V _M increases linearly. Similarly, the current speed signal G ₈ rather than the reference speed signal (−k)
When V _G is large, the drive voltage V _OUT becomes positive, and when the current speed signal G ₈ V _G is smaller than the reference speed signal (−k), the drive voltage V _OUT becomes negative and the servo motor 12 Operates so that the current speed signal follows the reference speed signal. Since the speed component is treated as a negative value in this embodiment, the current speed signal G ₈ V _{G is used as the} reference speed signal having a negative value.
Is followed, the servomotor 12 is controlled so as to rotate in the opening direction at a constant speed. FIG. 6 is an enlarged view of the curve a of the reference position signal V _S during the opening operation, the control curve b according to the conventional method, and the control curve c according to the present embodiment. Now, for some reason, when the value of the reference position signal V _S0 is larger than the value of the current position signal V _MO at time t ₀ , the drive voltage V _OUT applied to the servo motor 12 becomes positive, The opening position of the shutter blade 13 is accelerated (computedly delayed), and the current position signal V _M is brought close to the reference position signal V _S. In the conventional control method, the current position signal at time t ₂
When the V _M2 and the reference position signal V _S2 match, the servo motor
Although the drive voltage V _OUT for 12 becomes zero from 0, a large overshoot occurs as shown by the curve b due to the inertial force of the opening member, and the traveling of the shutter blade is not stable at all. On the other hand, in the present embodiment, at time t ₁ , the value of the reference position signal V _S1 is still larger than the value of the current position signal V _M1 , but the value of the current speed signal G ₈ V _G at this point is the reference speed signal (−
Since it is smaller than the value of k), the position deviation and the speed deviation cancel each other out, and the drive voltage V _OUT for the servomotor 12 reciprocates within a very small range from around this point to 0 V, for example, at time t ₂
When the positional deviation becomes zero, the shutter blade is in a traveling state in which it follows the reference position without causing a large overshoot. Next, the F value maintaining operation will be described. The sequence circuit 16 raises the timing control signal S ₂ at a desired timing, so that the reference position signal generation circuit 15 sets the reference position signal V _S to a constant level. At the same time, the sequence circuit 16 sets the timing control signal S ₅ to the H level and the timing control signal S ₆ to the L level, so that no current flows through the resistor R ₀ and the reference speed signal V ₇ indicates (Equation-2). It becomes a value. Thus, represented by Substituting the value of the reference speed signal V ₇ in Equation (-7) (formula -2), the output V ₃ of the operational amplifier A ₃ is (Equation -13). V ₃ = V _B −G ₈ V _G −G ₂ (V _S −V _M ) (Equation -13) Indicates the drive voltage V _OUT for the servo motor 12 (Equation −1)
Substituting (Equation −13) as the value of V ₃ in 1), the drive voltage V
_OUT becomes the value shown in the following (Equation-14). V _OUT = (1 + 2G ₄ ) ・ [G ₂ (V _S −V _M ) − (0−G ₈ V _M )]
In (Equation -14) As is apparent from equation (-14), in the same manner as when the shutter opening operation with respect to the position components at F value sustain operation, the servo motor 12 is current position signal V _M is follows the reference position signal V _S It is driven to do. Since the reference position signal V _S maintains a constant value during the shutter opening operation, the shutter blades 13 are controlled so that the current speed signal V _M maintains a constant value. Similarly, if the current speed signal G ₈ V _G is negative, the drive voltage V
_OUT becomes negative, and when the current speed signal G ₈ V _G is positive, the drive voltage V _OUT becomes positive, so the servo motor
Numeral 12 operates so that the current speed signal follows the reference speed signal, and the reference speed during the F value maintaining operation is 0, so the motor 13 is controlled to stop the rotation. FIG. 7 is an enlarged view of the curve a of the reference position signal V _S during the F value maintaining operation, the control curve b according to the conventional method, and the control curve c according to the present embodiment. Now, for some reason, when the value of the reference position signal V _S0 at time t ₀ is larger than the value of the current position signal V _M0 , the drive voltage V _OUT applied to the servomotor 12 becomes positive. The shutter blade 13 is moved in the opening direction to bring the current position signal V _M close to the reference position signal V _S. In the conventional control method, the current position signal V _M2 is changed to the reference position signal V _S2 at time t ₂ .
Drive voltage V _OUT for servo motor 12
Becomes zero from 0, but due to the inertial force of the aperture member, a large overshoot occurs as shown by the curve b, and the traveling of the shutter blade is not stable at all. On the other hand, in the present embodiment, the value of the reference position signal V _S0 is still larger than the value of the current position signal V _M0 at time t ₁ , but the value of the current speed signal G ₈ V _G at this time is the value of the reference speed signal. Since it is smaller than (= 0), the position deviation and the speed deviation cancel each other out, and the drive voltage V _OUT for the servomotor 12 reciprocates within a minute range near 0 V from this point, and the position deviation becomes 0 at time t ₂ , for example. The shutter blade follows the reference position without causing a large overshoot. Next, the shutter closing operation will be described. The sequence circuit 16 raises the timing control signal S ₃ at a desired timing, and the reference position signal generation circuit 15 lowers the reference position signal V _S in a polygonal line shape. At the same time, the sequence circuit 16 causes the timing control signal S ₅
Since both S ₆ are set to the L level, a current flows from the constant current source Ia to the resistor R ₀ , and the reference speed signal V ₇ becomes the value shown in (Equation-3). Thus, represented by Substituting the value of the reference speed signal V ₇ in Equation (-7) (Equation -3), the output V ₃ of the operational amplifier A ₃ is (Equation -15). _{V 3 = V B + k-} G 8 V G -G 2 (V S -V M) ( Equation -15) shows a driving voltage V _OUT for the servo motor 12 (Formula -1
Substituting (Equation −15) for the value of V ₃ in 1), the drive voltage V
_OUT becomes the value shown in the following (Equation-16). V _OUT = (1 + 2G ₄ ) ・ [G ₂ (V _S −V _M ) − (k−G ₈ V _G )]
(Equation-16) As is clear from (Equation-16), the servomotor 12 outputs the current position signal regarding the position component even when the shutter is closed.
V _M is driven so as to follow the reference position signal V _S. Then, when the shutter is closed, the reference position signal V _S decreases linearly, and the shutter blade 13 closes so that the current position signal V _M decreases linearly. Similarly, positive drive voltage V _OUT in the case the difference between the reference speed signal and the current speed signal is negative, and, if the difference between the reference speed signal and the current speed signal is positive driving voltage V _OUT to a negative Then, the servomotor 12 operates so that the current speed signal follows the reference speed signal. As described above, since the speed component is treated as a negative value in the present embodiment, the current speed signal G ₈ V _G follows the reference speed signal having a positive value, so that the servo motor 12 is kept constant. It is controlled to rotate in the closing direction at a speed. FIG. 8 is an enlarged view of the curve a of the reference position signal V _S during the closing operation, the control curve b according to the conventional method, and the control curve c according to the present embodiment. Now, for some reason, if the value of the reference position signal V _S0 at time t ₀ is smaller than the value of the current position signal V _M0 , the drive voltage V _OUT becomes negative and the shutter blade 13 is driven in the closing direction. Then, the current position signal V _M is brought close to the reference position signal V _S. In the conventional control method, when the current position signal V _M2 matches the reference position signal V _S2 at time t ₂ , the drive voltage V _OUT
Becomes positive from 0, but due to the inertial force of the opening member, a large overshoot occurs as shown by the curve b, and the traveling of the shutter blades is not stable at all. On the other hand, in the present embodiment, the value of the reference position signal V _S0 is still smaller than the value of the current position signal V _M0 at time t ₁ , but the value of the current speed signal G ₈ V _G at this time is the value of the reference speed signal. Since it is smaller than (= k), the position deviation and the speed deviation cancel each other out, and the drive voltage V _OUT reciprocates in a minute range near 0 V from this point, for example, at the time when the position deviation becomes 0 at time t ₂ . The shutter blade is in a traveling state that follows the reference position without causing a large overshoot. In the above, an example is shown in which one exposure operation is completed by a series of operations of shutter opening operation-F value maintaining operation-shutter closing operation. after generation of the timing control signals S ₁ by like, by immediately generates a timing control signal S ₃ without generating a timing control signal S _2,
It is also possible to shift from the shutter opening operation to the shutter closing operation, and even when the F value maintaining operation is performed, the opening F value can be freely adjusted by the generation timing of the timing control signal S ₂ . The structure and operation of the photometric circuit 24 itself may be well known in the art. Further, in the above, regarding the speed component, the example in which the sign is made negative is shown, but it is needless to say that the sign can be treated as plus depending on the polarity of the generator and the circuit configuration as a whole.

【effect】

As described above, according to the present invention, the reference speed signal is controlled corresponding to each of the opening operation, the F value maintaining operation, and the closing operation of the shutter blade, and the positional deviation and the speed deviation are controlled. Since the servo actuator is driven by the addition signal, for example, when the position deviation swings to the positive side, the servo actuator is basically driven in the direction of decreasing the position deviation, but in the direction of decreasing the position deviation, The current speed signal exceeds the reference speed signal due to driving, and the speed deviation swings to the negative side, so that the plus (minus) component of the position deviation is canceled by the minus (plus) component of the speed deviation. , Position deviation is 0
The overshoot in the vicinity of convergence to is suppressed, the overshoot amplitude can be reduced over the entire control region, and servo control with good followability becomes possible. Further, when the reference position signal and the reference velocity signal at the time of opening and closing of the shutter blade are made to have an inverted similar shape, the inertial force of the shutter opening / closing mechanism including the actuator is set at the time of opening and closing of the shutter blade. Since it is possible to make them substantially the same, it becomes easy to adjust various coefficients on the circuit and mechanical members. Further, when the reference position signal and the reference speed signal are controlled so that the absolute value of the operating speed of the servo actuator during the opening operation and the closing operation of the shutter blade is substantially constant, In addition, since the inertial force of the shutter opening / closing mechanism including the actuator can be made substantially constant at any point during the closing operation, it becomes easier to adjust various coefficients on the circuit and the mechanical members.

[Brief description of drawings]

FIG. 1 is a mechanism diagram showing a shutter according to one embodiment of the present invention, FIG. 2 is a block diagram showing one embodiment of the present invention, and FIG.
FIG. 4 is a time chart of the control operation of the present invention, FIG. 4 is a circuit diagram showing a concrete example of the reference position signal generating circuit, FIG. 5 is a circuit diagram showing one embodiment of the present invention, and FIG. 6 is a shutter opening operation. FIG. 7 is a characteristic diagram showing control characteristics when the F value is maintained, FIG. 7 is a characteristic diagram showing control characteristics when the F value is maintained, FIG. 8 is a characteristic diagram showing control characteristics when the shutter is closed, and FIG. 9 is a conventional servo system. Block diagram of. 12 …… Servo motor, 13 …… Shutter blade 14 …… Sub-aperture 15 …… Reference position signal generation circuit 16 …… Sequence circuit 20 …… Blade position detection circuit 21 …… Speed detection circuit, 22 …… Speed deviation calculation circuit 23 …… Reference speed signal generation circuit A _{1 to} A ₈ …… Op Amp

Claims (3)

[Claims] 1. A shutter servo control device in which an opening operation, an F value maintaining operation and a closing operation of a shutter blade are performed by a servo actuator, wherein the shutter blade is operated during an opening operation, an F value maintaining operation and a closing operation. A reference position signal generating circuit for sequentially generating a reference position signal for instructing the traveling position, a current position signal generating circuit for generating a current position signal indicating the actual position of the shutter blade, and an operating speed of the servo actuator A reference speed signal generating circuit for generating a reference speed signal, a current speed signal generating circuit for generating a current speed signal indicating the actual speed of the servo actuator, and a deviation between the reference position signal and the current position signal. A position deviation calculating circuit for calculating a position deviation, and a speed deviation which is a deviation between the reference speed signal and the current speed signal. And a drive means for driving the servo actuator according to an addition signal of the position deviation and the speed deviation, and the reference speed signal generation circuit includes an opening operation of the shutter blades. A servo control device for a shutter, wherein different reference speed signals are generated depending on time, F value maintaining operation, and closing operation. 2. A servo control device for a shutter according to claim 1, wherein the reference position signal and the reference speed signal at the opening operation and the closing operation of the shutter blade have an inverted similar shape. The servo control device for the shutter. 3. The shutter servo control device according to claim 1 or 2, wherein the absolute value of the operating speed of the servo actuator during the opening operation and the closing operation of the shutter blade is substantially constant. A servo control device for a shutter, characterized in that the reference position signal and the reference speed signal are controlled so as to obtain a high speed.