JP2553857B2 - Shutter speed servo controller - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a speed servo control device for a shutter, and more specifically, it uses a shutter blade that also serves as an aperture blade so that the F value can be maintained at the timing when an arbitrary F value is obtained during opening. The present invention relates to a novel speed servo control device for a shutter in which a control characteristic of a servo system is less likely to be disturbed by gently varying a speed command value when shifting from an operation to an F value maintaining operation.

[Prior art]

A so-called triangular aperture type program shutter is well known as a shutter mechanism using a shutter blade that also serves as an aperture blade. In the exposure control of this kind of triangular aperture type program shutter, the released shutter blades are opened approximately linearly by springs, governors and the like. Further, the exposure control circuit releases the shutter closing member at a timing corresponding to the field brightness and the film sensitivity to end the exposure operation. Therefore, when using this kind of shutter blade,
The combination of the aperture diameter and the exposure time for obtaining a certain exposure is uniquely determined, and the aperture diameter and the exposure time cannot be arbitrarily combined. Of course, if a member that restricts the opening position of the shutter blade is made to enter the traveling path of the opening mechanism of the shutter blade, and the amount of the restriction member entering and the shutter closing timing are related, the aperture diameter and the exposure time However, in this case, the shutter mechanism is complicated because it is necessary to provide the above-mentioned restricting member and a drive mechanism for this restricting member in the shutter mechanism. This is almost the same as the shutter mechanism in which each shutter blade is provided independently. Also, in the case of such a spring release type drive mechanism, the opening control of the shutter blades is basically open control, so if the aperture characteristics fluctuate due to changes in the camera posture or aging of the spring constant, etc. However, there is also a problem that the exposure accuracy decreases. Therefore, using shutter blades that also function as aperture blades, the aperture aperture and exposure time can be arbitrarily combined, and in order to obtain sufficient exposure accuracy, advanced servo control is used. It is desired to provide a control system.

[Problems to be Solved by the Invention]

By the way, the servo control itself is, for example, in NC machine tools,
It is well known that the control method has been widely adopted from the past, and the current value is controlled so as to follow the command value. However, in order to ideally follow the current value to the command value using servo control, it is necessary that the drive circuit side has a sufficiently large capacity as compared with the inertial force of a mechanical member such as a shutter blade. . However, in the case of the still color, there is a problem that the control system is liable to be out of step due to the reason that the power supply voltage is as low as a few V and only a small motor can be used due to the limitation of the arrangement space. Must use a large external power supply or external motor. Especially when the shutter blade is stopped at an arbitrary position during the opening operation, its speed command value fluctuates greatly, and the kinetic energy of the shutter blade is large during running. You have exceeded your capacity,
The current situation is that the control characteristics such as overshoot and step-out are likely to be disturbed.

[Means for solving problems]

The present invention has been made in view of such a current situation,
The first purpose is to use a shutter blade that also serves as a diaphragm blade, and it is possible to arbitrarily combine the aperture diameter and the exposure time in exposure control without providing a member for limiting the aperture diameter. It is to provide a novel shutter speed servo control device, and the second object thereof is to provide a speed servo control when the shutter blades during the opening operation are stopped when a constant F value is obtained. By reducing the command value stepwise or continuously, you can use a large power circuit or large motor without using
An object of the present invention is to provide a novel speed servo control device for a shutter in which control characteristic disturbances such as overshoot and out-of-step caused by a change in speed command value exceeding the response capability of a servo system are less likely to occur. . In order to achieve the above object, the shutter speed servo control device of the present invention includes: speed command generating means for generating a speed command signal for the shutter blade that also serves as the diaphragm blade, and for generating a current speed signal for the shutter blade. Speed detection means,
In a speed servo control device for a shutter, comprising: a servo actuator that drives the shutter blades corresponding to a deviation between the speed command signal and the current speed signal:
The speed command generating means includes an opening speed command signal generating source for generating a positive opening speed command signal, a closing speed command signal generating source for generating a negative closing speed command signal, and the opening in response to a shutter release operation. By selectively using the speed command signal source, the shutter blade is driven to open,
By stopping the use of both speed command signal generation sources at the timing corresponding to the desired aperture value, the shutter blades are stopped at the desired aperture value, and the closing speed command signal at the timing corresponding to the desired exposure time. And switching control means for closing and driving the shutter blade by selectively using a generation source: at least when the selective use of the opening speed command signal generation source is switched to the suspension of both speed command signals It is designed to gently change the signal.

[Action]

That is, according to the shutter speed servo control device of the present invention, in the speed command value following type speed servo, the value of the speed command signal is substantially zero at any timing during the opening operation.
With this, the shutter blade that also serves as the diaphragm blade can be stopped at an arbitrary position to obtain an arbitrary aperture. In this case, setting the value of the speed command signal to substantially zero means that the value of the signal component excluding the bias point and the like in the speed command signal is zero. Further, since the speed command signal fluctuates gently, it is difficult for the control characteristics to be disturbed, such as overshoot or step-out, due to the fluctuation amount of the speed command signal exceeding the response of the servo system. Note that, for example, the speed command signal is changed by switching the current value supplied from the current addition / subtraction circuit to the resistor. Further, the speed command signal is gently changed by switching the output current of the current adding / subtracting circuit stepwise. Alternatively, a capacitor is connected in parallel with the resistor, and the speed command signal is gently changed according to the discharge time constant of the capacitor when the output current of the current adding / subtracting circuit is switched.

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
You. First, FIG. 1 shows a shutter mechanism according to one embodiment of the present invention.
FIG. 3 is a view of the image when viewed from the photographing lens side. In the figure, 10 is the shutter base plate, 11 is the sectoring, and
Kuta ring 11 is aperture center P₁Arc centered at
It is supported so as to rotate a certain angle up. Also, M is rotating
Direction / rotation position and rotation speed can be controlled
It is a servo motor, and the output pin 12 of the servo motor M is
Data sensor P₂Moves on a circular arc centered at.
In this embodiment, the output pin 12 of the servo motor M
Is the position when no voltage is applied to the servomotor M
Stop at, and when a positive voltage is applied, move to the left on the drawing
When moving and applying a negative voltage, to the right on the drawing
Moving. In addition, the moving speed is determined by the absolute value of the applied voltage.
You. The lever formed protruding from the sector ring 11
-11d is engaged with the output pin 12. Also, 13 is a shutter blade that also serves as a diaphragm blade, and
The blade 13 is rotatably supported by the shaft 10a on the shutter base plate 10.
The long hole 13a formed in the shutter blade 13
Sector pin 11a formed by projecting on the sector ring 11
Are 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 M
Is rotated in the direction of arrow A, the shutter blade 13
While the long hole 13a is engaged with the sector pin 11a, the shaft 10a
Turn left as a heart. Also, not shown in FIG.
However, the shutter blades are also attached to the shafts 10b and 10c on the shutter base plate 10.
The shutter blade, which has at least the same blade shape as 13
The two shutter blades (not shown) are movably supported.
Similar to the shutter blade 13, it is connected to the sector pins 11b and 11c, respectively.
It is designed to swing together,
And rotate the sector ring 11 in the direction of arrow A, the shaft 10b
・ Two shutter blades (not shown) supported by 10c
Since it rotates counterclockwise about the axes 10b and 10c, the aperture 11
e starts opening. (Shutter opening operation) Also, the aperture of the aperture 11e was made in this way.
The applied voltage to the servo motor M at 0V
Then, the servo motor M, the sector ring 11 and the shutter blade
Root 13 stops at that position, so aperture 11e
Maintain a constant F value. (F value maintaining operation) Further, in the open state, the servo motor M is negatively charged.
By applying pressure, the sectoring 11 is moved in the direction of arrow B.
When rotated, the shutter blade 13 moves right about the axis 10a.
Two shafts (not shown) that are rotated and supported by the shafts 10b and 10c
Since the blades of the blades also rotate right about the axes 10b and 10c respectively,
The aperture 11e is closed and the exposure operation ends.
(Shutter Closing Operation) As described above, the shutter mechanism shown in FIG.
The aperture diameter and exposure time can be adjusted by controlling the rotation of the
The exposure can be controlled by a combination, and in the present invention, the exposure can be controlled.
Controls the rotation speed and direction of the bomotor M. That is, (1) the rotation speed of the servo motor M is made positive.
As a result, the shutter blade 13 opens, and (2)
The shutter is set by setting the rotation speed of the servomotor M to 0.
The blade 13 operates to maintain the F value, and (3) turns the servomotor M.
The shutter blade 13 is closed by setting the rolling speed to a negative value.
The chain works. FIG. 2 shows the shutter speed servo controller of the present invention.
FIG. 20 is a block diagram theoretically showing that 20 generates a speed command signal.
Speed command generator circuit, A₃Is the speed command signal and the current speed
Deviation amplifier to calculate deviation, M is servo motor, SA is speed
Servo motor that drives the servo motor M according to the deviation
P, G is the tacho generator, 21 is the tacho generator G output
An integrator circuit that integrates forces over time to generate a position signal, 22 is a product
Detects when the output value of the minute circuit 21 reaches a certain value
Position detection circuit, and 23 is a sequencer for controlling the operation sequence.
Each of the sense circuits is shown. Now, in FIG. 2, the speed command generation circuit 20
Deviation amplifier A for command signal (voltage)₃Mark for normal phase input of
When added, deviation amplifier A₃Is the speed command signal and tachogenerator
The deviation from the current speed signal (voltage) generated by data G
The servomotor M is driven in addition to the amplifier BO.
The current speed of the servo motor M is the tacho generator.
Deviation amplifier A detected by G₃Servo because it is added to
The system as a whole has zero deviation between the speed command signal and the current speed signal.
So that the current speed signal follows the speed command signal
It acts like you do. Also, the current speed signal generated by the tacho generator G is the product
The time is integrated by the minute circuit 21,
The output is a shutter blade driven by a servo motor M
It will show 13 positions. And the output of the integrating circuit 21
Position detection circuit 22 when the position signal reaches the preset value.
The sequence circuit 23 is activated by the detection signal generated by
Command output 20 to switch the speed command signal appropriately.
Control. As mentioned above, the shutter mechanism shown in FIG.
The opening operation is performed by shifting from the state to the moving state,
(2) F value by shifting from the moving state to the stopped state
Maintaining operation, (3) Transition from stopped state to moving state again
By doing so, the closing operation is performed. Shown in Figure 2
Using a speed servo system that
When controlling, the speed command generation circuit 20
The opening operation is controlled by generating a speed command signal
(2) ± 0 to generate a speed command signal
The value is maintained and (3) negative speed command signal is issued.
It causes a closing motion by generating. By switching the speed command signal in this way, the shutter blade
When changing the traveling direction of 13, change the traveling direction.
Point, that is, (1) when shifting from the initial state to the opening operation,
(2) When shifting from opening operation to F value maintaining operation, (3)
In each case of transition from F value maintaining operation to closing operation
There is a risk that the control characteristics will be disturbed. Sometimes from opening operation to F
When shifting to the value maintaining operation, the shutter blade 13 and its
Kinetic energy during running is stored in the accessory mechanism.
Therefore, overshoot and out-of-step easily occur. Therefore, in the present invention, the inflection point in such a traveling direction is
Servo by gently changing the speed command signal
It is designed to reduce the disturbance of the control characteristics of the system. FIG. 3 shows an example of a circuit for performing such control operation.
The speed servo system shown in the block diagram in Fig. 2.
It is more concrete. In addition, even in FIG.
The same symbols as those in FIGS. 1 and 2 are used for the elements described.
A duplicate description will be omitted. In FIG. 3, reference numeral 24 is a bias power supply circuit,
The power supply circuit 24 has a resistance R₁And resistance R₂Voltage level of
Zifoloa A₁It is designed to be output via. this
Voltage Follower A₁Bias voltage V which is the output of₁Is usually
Voltage Follower A Through Anti-Rx₂In addition to the in-phase input of
And the operational amplifier A that composes the servo amplifier SA._Four
Positive phase input and operational amplifier A_FiveApplied to the negative phase input of
You. Also, the speed command generation circuit 20 uses the current of the current mirror configuration.
It has an adder / subtractor circuit.
Voltage generated across resistor Rx when current is applied to resistor Rx
Is superimposed on the output of the bias power supply circuit 24
V₂As Voltage Follower A₂It will be output from
Have been. The detailed configuration of the current adding circuit 20 is
As will be described later, in the present embodiment, (1) stopped state
Opening operation is performed by shifting from the
By (2) shifting from the moving state to the stopped state,
When the F value maintenance operation is performed, (3) move from the stopped state again
In each case when the closing operation is performed by shifting to the state
, The current supplied to the resistor Rx from the current addition / subtraction circuit
An appropriate speed command signal is generated by switching the quantity Ix.
It is made to live. And, in this embodiment, as a characteristic point,
A capacitor 20a is connected in parallel with the resistor Rx to cut off the current Ix.
At the time of replacement, charging / discharging the capacitor 20a with the current Ix
Therefore, the voltage across the terminals of the resistor Rx fluctuates slowly.
ing. This voltage follower A₂Command signal which is the output of
V₂Is the deviation amplifier A₃Configure the positive-phase input and integration circuit 21 of
Operational amplifier A₆Has been added to the positive phase input of. Deviation amplifier A₃Reverse-phase input resistance R_FourOf the servomotor M
Currently, the tacho generator G is generated according to the rotation speed.
Speed signal V_GIs added in a superimposed manner, deviation amplifier A₃Is
Speed command signal V₂And the current speed signal V₆Velocity deviation which is the deviation of
Signal V₃To occur. Then, the speed deviation signal V₃Is Servo
Amplifier A that composes pump SA_FourOpposite phase input and operation
Type A_FiveAdded to the positive phase input. The characteristic points of the servo amplifier SA of this embodiment are
Operational amplifier A_FourFor its positive phase input,
Pressure V₁Is added, the speed deviation signal is
Issue V₃Is added to op amp A_Fiveabout
Bias voltage V₁Is added,
Velocity deviation signal V₃Has been added. Follow
Operational amplifier A_FourAnd operational amplifier A_FiveThe output polarity is
It will be overturned. And operational amplifier A_FourAnd Opean
Type A_FiveThe output potential difference of the
Is applied as
Can be wide. Next, in the integrating circuit 21, the capacitor C is connected as a feedback resistor.
Op Amp A followed₆Having. Also, operational amplifier A₆The opposite of
Resistance R to phase input₆Transistor 21 connected through
a is for initial resetting of the integrating circuit 21. Implementation
In the example integrator circuit 21, the transistor 21a is
It is designed to be conductive and has a resistance R₆Through Transis
The current supplied from the converter 21a charges the capacitor C,
Position signal V which is the output of the branch circuit 21₆Is 0V. So
Then, when the transistor 21a is cut off, the speed
Resistance R_FiveCapacitor C is discharged by the current flowing through
Position signal V that rises with this₆Is the integral of velocity
Will be shown. Position signal V output from the integrator circuit 21₆Exposure control operation open
Comparator C for auto trigger for start₁And flag
Comparator C for caliber detection in Schmatic₂of
Applied to each positive phase input. The comparator C₁The reference power source 22a of the shutter blade 13
The potential is set to correspond to the pinhole position of. Also,
Impalator C₂Reference power supply 22b is for shooting distance and film sensitivity
Corresponding to the appropriate F value at the time of strobe tuning determined in accordance with
The potential is variably set. Next, 25 is the photoelectric flowing in the light receiving element 25a after the auto trigger.
Photometric circuit to measure the field brightness by the flow, 26 is a trigger
Strobe uni that causes the strobe to fire
, 27 is a shooting lens helicoid or
Generates a distance signal to the subject in conjunction with a distance measuring circuit for dust
Distance input unit, 28 is a film sensitivity setting mechanism or
The mechanism for reading the film sensitivity described in
Film speed input that moves to generate a film speed signal
And 29 are shutter release switches.
It is knowledge. Next, the above matters, the flowchart of FIG. 4 and the flowchart of FIG.
The operation of this embodiment will be described with reference to the time chart. First, in the initial state, the sequence circuit 23
The outputs a, b, c and d are as shown in Table 1. Control output a of the sequence circuit 23 goes to L level
Causes the transistor 21a to conduct and the transistor 21a
Resistance R₆The current supplied via the
Operational amplifier A₆Position signal V which is the output of₆Is ground level
Falls to. Also, voltage follower A₁Is resistance R₁・ R₂Partial pressure level
Is output as is, the output of the bias voltage setting circuit 24
Bias voltage V which is the force₁Is represented by (Equation 1). And voltage follower A₂Resistor Rx for positive phase input
The voltage generated across the resistor Rx when the current Ix flows is bypassed.
As voltage V₁The voltage superimposed on the
Lower A₂Since the output voltage of is equal to the positive phase input voltage,
Speed command signal V generated by the degree command generation circuit 20₂Is the expression (
2). This speed command signal V₂Is the deviation amplifier A₃In addition to the in-phase input
Deviation amplifier A₃Reverse-phase input resistance R_FourTaco generator
Current speed signal V generated by G₆Is superimposed and added
Deviation amplifier A₃Velocity deviation signal V which is the output of₃Is
It is shown by the following (Equation 3). And operational amplifier A_FourIs a bias voltage applied to its positive input.
Pressure V₁Is added, and the velocity deviation V₃Is added
Therefore, the operational amplifier A_FourIf the gain of G is G
Pump A_FourOutput voltage V_FourIs given by (Equation 4). V_Four= V₁-G (V₃−V₁) (Equation 4) Similarly, operational amplifier A_FiveIs a bias voltage applied to its negative phase input.
Pressure V₁Is added, and the velocity deviation V₃Is added
Therefore, the operational amplifier A_FiveGain of Op Amp A_FourGain of
If G is equal to_FiveOutput voltage V_Five(formula
Given in 5). V_Five= V₃-G (V₁−V₃) (Equation 5) The operational amplifier A is provided for the servo motor M._FourOutput voltage of
V_FourAnd operational amplifier A_FiveOutput voltage V_FiveDifference is given as the drive voltage
Therefore, the driving voltage is given by the following (Equation 6). Drive voltage = (2G + 1) (V₁−V₃) (Equation 6) In the servo system as shown in Fig. 3, the drive voltage becomes 0V.
Therefore, (Equation 7) is added to the servo system.
It becomes a subordinate condition. V₁−V₃= 0 (Equation 7) Substituting (Equation 1) and (Equation 7) into (Equation 7),
Removing a bias voltage leads to (Equation 8). Therefore, the servo system as a whole flows through the resistor Rx
The current speed is applied to the speed command signal set by the current Ix.
Output voltage V of tacho generator G_GTo follow
Will work. Now, to supply the current Ix to the resistor Rx,
If the circuit is described in detail, the speed command generation circuit 20 has already been explained.
In addition to the configuration shown, the constant current source 20b, the constant current source 20b
Current equal to the current flowing through each transistor
Control of the weighting current circuit 20c and the sequence circuit 23
Current switch Sb ・ Sc operated by output b ・ c ・ d
-Has Sd. All transistors in weighting current circuit 20c are base
・ The junction area ratio between emitters is the same,
Within D₁And D₂Is shortened between base collectors
Acts as a code. Diode D₁The base-emitter voltage of the diode
D₁And the current flowing in the series circuit of the constant current source 20b
The diode D in the weighting current circuit 20c₁And base
Diode D for all transistors sharing₁Flow to
Current equal to the current that flows. Therefore, if the current value of the constant current source 20b is i,
Diode D in mounting current circuit 20c₁Share the base with
A current whose current value is i flows through all the transistors.
You. In addition, each current switch Sb / Sc / Sd is a switch for switching.
Transistor S, transistor D that functions as a diode,
Has a transistor T that functions as a constant current circuit
You. And the diode D in the current switch Sb and the switch
A weighting current circuit is provided at the interconnection point of the switching transistor S.
Current is supplied from two transistors in 20c,
Diode D and switching transistor in switch Sc
One of the weighting current circuits 20c is connected to the interconnection point of
Current is supplied from the transistor, and the current switch Sd
Interconnection point between the diode D and the switching transistor S
From the six transistors in the weighting current circuit 20c
Electric current is being supplied. Therefore, each current switch Sb ・ Sc
・ When the switching transistor S in Sd is conducting
From the weighting current circuit 20c to each current switch Sb ・ Sc ・ S
The current supplied to d passes through the switching transistor S.
Flow through to the ground, but a switching transistor
When S is cut off, each voltage is fed from the weighting current circuit 20c.
Current supplied to the current switches Sb, Sc, Sd is diode D
Flows to The transistor T, which is a constant current circuit, is a diode.
Sharing the base with D and connecting the base-emitter junction
Since the product ratio is the same, it is equal to the current flowing in the diode D
Current flows through the transistor T. The transistor T in the current switch Sb is a weighted current circuit.
Diode D in path 20c₂Connected in series with the die
Aether D₂And diode D₂To share a base level with
The transistor T in the current switch Sb flows through the transistor.
A current equal to the current flowing will flow. And diode D₂When
The collector of the transistor sharing the base is connected with the resistor Rx.
Peamplifier A₂Since it is connected to the interconnection point of
The switching transistor S of the switch Sb is cut off.
And resistance Rx to voltage follower A₁Towards the output of
A current with a current value of 2i flows. (In this specification,
The direction of current in this direction is treated as positive. ) Also, the collector of the transistor T in the current switches Sc and Sd
Resistor is Rx and operational amplifier A₂Directly to the interconnection points of
Has been continued. Therefore, the switch in the current switch Sc
When the switching transistor S is cut off, the resistance Rx has a current value
Negative i current flows, switch in current switch Sd
When the switching transistor S is cut off, the resistance Rx has a current value
Is a minus 6i current. Now, in the initial state, the control output b.
As shown in Table 1, c and d are all H level. Therefore, the current value flowing through the resistor Rx is ± 0i,
The value of RxIx in (Equation 8) becomes 0, and the servomotor M
Is the current speed signal V generated by the tacho generator G_GTo 0
Is driven to become. That is, the servomotor M stops
There is. In addition, the film sensitivity input unit 28 receives the film sensitivity signal.
The strobe unit 26 is provided to the can circuit 23 and the strobe unit 26
Pop-up signal (for example,
Sequence the signal that indicates that the robot has popped up
Add to circuit 23. First, the case where the strobe mode is not set will be described. If no pop-up signal is added, the sequence
The circuit 23 waits for the shutter release switch 29 to turn on.
Then, when the shutter release switch 29 is turned on,
The control circuit 23 shows each control output a, b, c, d in Table 2.
Like When the control output b becomes L level, the current switch Sb switches
Since the switching transistor S is cut off, the resistance Rx
The value of the flowing current Ix is plus 2i, and both ends of the resistor Rx
A voltage is generated due to the flow of the plus 2i current Ix,
Degree command signal V₂Value of 2R than when stopped_xi rises only. A characteristic point of this embodiment is that the resistance Rx
Since a capacitor 20a is connected in parallel to
The capacitor 20a is linearly charged with a positive 2i current,
Until the charging level of the Densa 20a becomes plus 2Rxi,
The voltage generated in the resistor Rx will rise linearly.
Therefore, the speed command signal V₂Does not rise instantaneously, but linearly
Rise gently. And the servo amplifier SA is the deviation amplifier A₃Output of 0
Since the servo motor M is driven so that
M rotates at a speed proportional to plus 2Rxi,
The rotation of M is transmitted by the mechanism shown in FIG.
The shutter blade 13 starts the opening operation. Thus, in this embodiment, the shutter blades 13 are
When opening operation is started by shifting to the moving state
The speed command signal does not rise instantaneously,
Servo amplifier SA and servo motor M
Can be sufficiently tracked, and the speed command
Disturbance of control characteristics may occur due to exceeding the response capability of the system.
It's hard to beat. On the other hand, when the control output a becomes H level, the integration
Transistor 21a of path 21 is cut off and resistor R₆Is conden
Separated from SA C. Operational amplifier A₆Is the speed command signal V₂Added
The reverse phase input resistance R_FiveSpeed deviation signal V₃Added
Therefore, as shown in (Equation 2) and (Equation 3), the speed command signal V₂
Is the speed deviation signal V₃Than (R₃/ R_Four) V_GOnly big. And operational amplifier A₆Between the positive and reverse input terminals of
Since it is a short circuit, the resistance R_FiveAt both ends of (R₃/ R_Four) V
_GA potential difference shown by is generated, and this potential difference causes resistance R
_FiveThe capacitor C is discharged by the current flowing in the
Position signal V, the output of path 21₆Rises. The discharge current of the capacitor C at this time is the tacho for speed detection.
Output voltage V of generator G_GIs determined in proportion to
And the position signal V₆Is the shutter blade 13 which is the time integral of speed
Will indicate the current position of. Now, the sequence circuit 23 has its control outputs a, b, c,
After combining d as shown in Table 2,
Data C₁Monitor the output of. Then, the shutter blade 13 opens to the pinhole position.
Comparator C₁Position signal V applied to the positive phase input of₆
Has reached the level of the reference power supply 22a and the comparator C₁Output
Is inverted to H level, the sequence circuit 23 controls the exposure.
To start. That is, in the sequence circuit 23, F
Pre-programmed combinations of values and exposure seconds
Sequence circuit 23 is comparator C₁Output is H level
When it is turned on, it is based on the photocurrent applied from the photometry circuit 25.
The timing to shift to the F value maintenance operation and the exposure end timing
Calculate ming. Also during this period, the control output a generated by the sequence circuit 23
・ The combination pattern of b ・ c ・ d is as shown in Table 2.
Therefore, the shutter blade 13 continues to open at a constant speed.
You. Then, the sequence circuit 23 shifts to the F value maintaining operation.
At the timing, each control output a, b, c, d is set to the third
Switch as shown in the table, and after a predetermined time, see Fig. 4.
By switching as shown, the speed command signal V₂The step by step
Lower to.  Control generated by the sequence circuit 23 as shown in Table 3
When output c becomes L level, switch of current switch Sc
Since the switching transistor S is cut off, the resistor Rx has a current
The current flowing in the switch Sb changes from the current flowing in the current switch Sc.
An electric current with reduced flow will flow. Therefore, the value of the current Ix flowing in the resistor Rx is
The voltage across the resistor Rx also decreases.
Speed command signal V₂Also falls corresponding to a small amount of current source. In this embodiment, the resistor Rx is connected in parallel.
Since the capacitor 20a is discharged through the resistor Rx,
Command signal V₂Is the switching transistor S of the switch Sc
When the capacitor 20a is released,
It decreases with electricity. And the servo amplifier SA is the deviation amplifier A₃Output of 0
Since the servo motor M is driven so that
Speed command signal V₂, The servo motor M becomes positive
Rotating at a speed proportional to Rxi, opening speed of shutter blade 13
The degree decreases as shown in FIG. Continuing, as shown in Table 4, sequencer 23 is generated.
When all control outputs a, b, c, d become H level, all
Switching Transistors of all current switches Sb / Sc / Sd
Since the current S becomes conductive, no current flows through the resistor Rx,
Speed command signal V₂Is the bias voltage V₁Is equal to. Obedience
Then, the servomotor M is driven so that the speed becomes 0,
The chatter blade 13 maintains a constant F value and stops. Thus, in this embodiment, the shutter blade 13 is
When performing the F value maintaining operation by shifting to the stopped state
The speed command signal gradually and gradually decreases
To reduce the effects of overshoot during stoppage.
You can The sequence circuit 23 performs the F value maintaining operation in this way.
After that, control output until the exposure end timing.
Maintain forces a, b, c and d. Then, the sequence circuit 23 reaches the exposure end timing.
Then the control outputs a, b, c and d are cut as shown in Table 5.
Change. As shown in Table 5, when the control output d becomes L level,
The switching transistor S of the current switch Sd is cut off.
Therefore, the value of the current Ix flowing through the resistor Rx becomes minus 6i.
Therefore, a current Ix whose value is minus 6i flows across the resistor Rx.
Voltage is generated, and the speed command signal V₂The value of
Iias voltage V₁Than 6R_xThe value is reduced by i. In this embodiment, the resistor Rx is connected in parallel.
The charged capacitor 20a is linearly charged with a current of -6i
Then, the charge level of the capacitor 20a becomes minus 6 Rxi.
Until that time, the voltage developed across the resistor Rx can decrease linearly.
Therefore, the speed command signal V₂Instantly drops
Instead, it decreases with a straight slope. And the servo amplifier SA is the deviation amplifier A₃Output of 0
Since the servo motor M is driven so that
Speed command signal V₂Is the bias voltage V₁Lower than
The servomotor M rotates at a speed proportional to minus 6Rxi,
The shutter blade 13 is to the return end as shown in FIG.
Close and end the exposure operation. Thus, in this embodiment, the shutter blades 13 are
When starting the closing operation by shifting to the moving state
, The speed command signal gradually decreases.
And the servo motor M can follow sufficiently,
Control when the speed command exceeds the response capability of the servo system
Disturbance of characteristics is unlikely to occur. Next, the case of the strobe mode will be described. When a pop-up signal is added, the sequence circuit 23
Performs strobe mode operation. Even in strobe mode, the exposure control action is basically
Same as above, but the sequence circuit 23 pops up.
When the signal is applied, the shooting distance signal is read from the distance input unit 27.
From the shooting distance signal and film sensitivity input section 28
Proper exposure depending on the film sensitivity signal already input
Calculate the F value at which the output is obtained and
Set the pressure to the reference power source 22b and set the shutter release switch 2
Wait for 9 to turn on. Then, when the shutter release switch 29 is turned on,
The sequence circuit 23 opens the shutter blades 13 as described above.
Comparator C that performs mouth operation and detects pinholes₁Out of
When the force becomes H level, the exposure control operation is started. The shutter blade 13 is further opened so that the integration circuit
Position signal V, which is the output of 21₆The level of
Signal V₆Is the level of comparator C₂Reference power supply 22b level
Reaches the comparator C₂When the output of becomes H level,
The sequence circuit 23 sends a trigger signal to the strobe unit 26.
Send it to make the flash fire. Also, comparator C₂Before the output of turns to H level
When it comes to the exit end timing, the flash
Send a trigger signal to the unit 26 to make the strobe light
You. Next, FIG. 6 shows another embodiment of the present invention.
The difference from the embodiment shown in FIG. 2 lies in the embodiment shown in FIG.
Current switch S for opening operation instead of the capacitor 20a
Capacitor 20d is inserted in parallel with diode D of b
Is a point. Therefore, when the opening operation is started in the embodiment shown in FIG.
The switching transistor S of the current switch Sb is cut off.
Then, when the capacitor 20d is charged, the diode D
The source-emitter voltage rises, and the current source
The current flowing through the transistor T, which is a road, gradually increases.
Speed command signal V₂Will gradually rise. In addition, in the above, the shutter blade in the moving state is
When the F value maintaining operation is performed after shifting to the stop state, the resistance
Example of reducing the current supplied to Rx in two steps
Although shown, the number of stages of the weighted current circuit 20c and the current switch
The number of stages of is increased and the current supplied to the resistor Rx is reduced in multiple stages.
You may let it go down. In addition, in the above, the shutter blade in the closed state is
When shifting to the open state, it is faster by charging the capacitor.
Degree command signal V₂Showed an example of gradually increasing
However, without using a capacitor, the weighting current circuit 20c stage
The number and the number of current switch stages are increased and supplied to the resistor Rx.
The current may be increased stepwise.

【effect】

As described above, according to the present invention, the shutter blade that also serves as the diaphragm blade is used, and the aperture diameter and the exposure time are arbitrarily combined in the exposure control without providing the member for limiting the aperture diameter. Therefore, the opening mechanism of the shutter can be simplified. According to the present invention, the inflection point of the traveling direction of the shutter blades, especially when the kinetic energy of the shutter opening mechanism is large, as in the case of stopping the shutter blades during the opening operation at a constant F value, Since the speed command signal can be changed gradually and gradually, the amount of change in the speed command value in servo control of the shutter mechanism for a still camera, which is greatly restricted by the power supply voltage and the torque capacity of the motor, determines the response capacity of the servo system. It is less likely to exceed, and the disturbance of control characteristics such as overshoot and step-out caused by the change in command value exceeding the response capacity of the servo system is less likely to occur, making it easy to obtain ideal control characteristics. become. Further, according to the present invention, the exposure accuracy is unlikely to be deteriorated due to the change of the camera posture and the secular change of the spring constant as in the spring release type shutter drive mechanism. Further, according to the present invention, the current speed detected by the speed detecting means is integrated to obtain the position signal, and the starting point of the timing for switching the speed command signal and other control timings are determined, so that it is independent. It is also possible to obtain sufficient positioning accuracy without providing a position detection device.

[Brief description of drawings]

1 is a mechanism diagram of a shutter to which the present invention is applied, FIG. 2 is a block diagram showing one embodiment of the present invention, and FIG. 3 is a more specific circuit of the embodiment shown as a block diagram in FIG. FIG. 4 is a flow chart for controlling the embodiment shown in FIG. 3, FIG. 5 is a time chart of the embodiment shown in FIG. 3, and FIG. 6 is a flowchart of the embodiment shown in FIG. The circuit diagram which shows a modification. 13 ... Shutter blade, M ... Servo motor G ... Tacho generator, SA ... Servo amplifier 20 ... Speed command circuit, Rx ... Resistor 20a ... Capacitor, 20b ... Constant current source 20c ... Weighting current circuit 20d ...... capacitor Sb · Sc · Sd ...... current switch 21 ...... integrating circuit, C ...... capacitor C ₁ · C ₂ ...... comparator A ₁ · A ₂ ...... voltage follower A ₃ ...... deviation amplifier A ₄ · A ₅・ A ₆ …… Op Amp

Claims (5)

(57) [Claims] 1. A speed command generating means for generating a speed command signal for a shutter blade that also serves as a diaphragm blade, a speed detecting means for generating a current speed signal for the shutter blade, the speed command signal and the current speed signal. In a shutter speed servo control device having a servo actuator for driving the shutter blades in accordance with the deviation of, an opening speed command signal generation source for generating a positive opening speed command signal, A closing speed command signal source for generating a negative closing speed command signal and an opening speed command signal source for selectively using the opening speed command signal source in response to a shutter release operation are used to drive the opening of the shutter blades to obtain a desired aperture value. Stops the shutter blades at a desired aperture value by stopping the use of both speed command signal generation sources at the timing corresponding to Then, the shutter speed is closed and driven by selectively using the closing speed command signal generating source at a timing corresponding to the desired exposure time, and at least both speed commands are selected by using the opening speed command signal generating source. A speed servo control device for a shutter, comprising: a switching control means for gently varying the speed command signal when switching to the stop of use of a signal. 2. A shutter speed servo controller according to claim 1, wherein the speed command generating means includes a current addition / subtraction circuit, a resistor supplied with current from the current addition / subtraction circuit, and the current addition / subtraction. An output circuit that outputs a voltage generated in the resistor as a speed command signal in response to a current supplied from the circuit to the resistor, and the switching control means switches the addition / subtraction operation of the current addition / subtraction circuit. The shutter speed servo control device is characterized in that the speed command signal is controlled accordingly. 3. A shutter speed servo control device according to claim 2, wherein the speed command generating means gradually decreases the output current of the current adding / subtracting circuit to open the shutter blade. A speed servo control device for a shutter, characterized in that a speed command signal when shifting from a stop operation to a stop operation is gently changed. 4. The shutter speed servo control device according to claim 2, wherein a capacitor is connected in parallel with the resistor, and the capacitor is connected in parallel with the time constant of the capacitor when the output current of the current addition / subtraction circuit is switched. A speed servo control device for a shutter, characterized in that a speed command signal is gently changed. 5. A shutter speed servo controller according to any one of claims 1, 2, 3, or 4, wherein the output of the speed detecting means is integrated over time so that the shutter blade A speed servo control device for a shutter, wherein an opening position is detected and a switching timing of the speed command signal is calculated.