JP2553856B2 - Speed servo controller for camera mechanical member - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a speed servo control device for a mechanical member of a camera such as a diaphragm blade, a shutter blade also serving as a diaphragm blade, or a helicoid of a photographing lens, and more specifically, a displacement position is calculated by integrating a speed detection signal for speed servo. With
The present invention relates to a speed servo control device for a mechanical member of a camera in which servo response is improved by grading a change in command speed from a stopped state to a moving state and a change in command speed from a moving state to a stopped state.

[Prior art]

As is well known, automatic focusing and automatic exposure of cameras have spread from so-called compact cameras, and in recent years, they have also become popular into so-called high-end cameras such as single-lens reflex cameras. With automatic focusing and automatic exposure, it is necessary to automatically operate mechanical members of the camera such as diaphragm blades, shutter blades that also function as diaphragm blades, or helicoids of photographing lenses. However, servo control is required for each control. There is a demand for high-precision automation using the above.

[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, but in order to ideally follow the command value with the current value, for example, the drive circuit is compared with the inertial force of mechanical members such as shutter blades. It is necessary that the ability of the side is large enough. However, in the case of a still camera, the power supply voltage is as low as a few volts, and the control characteristics are disturbed due to reasons such as the limitation of the layout space and only a small motor can be used. When the speed command value fluctuates greatly, such as when shifting from the stop state to the stopped state, the fluctuation amount of the speed command value exceeds the response capability of the servo system, and the control characteristics are liable to be disturbed. It is the current situation. Also, if only the speed servo is controlled in this way, sufficient position accuracy cannot be obtained unless the target speed perfectly follows the command speed. However, the conventional speed servo control device for a camera responds accordingly. There was also the problem of not having sufficient speed control accuracy to obtain sufficient position accuracy.

[Means for solving problems]

The present invention has been made in view of such a current situation,
The servo system is used even when shifting from a stopped state to an operating state or from an operating state to a stopped state, under the constraint that the power supply voltage is low and only a small motor can be used from the viewpoint of installation space. It is an object of the present invention to provide a speed servo control device for a mechanical member of a camera capable of reducing the disturbance of the control characteristic caused by exceeding the limit of the response capability of the above. In order to achieve such an object, the speed servo control device of the mechanical member of the camera of the present invention is provided in the camera:
The servo actuator has speed command generating means for generating a speed command signal of a mechanical member and speed detecting means for generating a current speed signal of the mechanical member: the servo actuator has the speed command signal and the current speed. In a speed servo controller for a mechanical member of a camera adapted to drive the mechanical member in response to a deviation from a signal, the output of the speed detecting means is integrated over time to generate a current position signal of the mechanical member. Integrating means: The speed command signal generating means includes a current adding / subtracting circuit having a plurality of selectively used current sources, and voltage converting means for converting an output current of the current adding / subtracting circuit into a voltage. Between the stop state and the moving state of the mechanical member by switching the output current of the current adding / subtracting circuit in response to the current position signal generated by the integrating means. Cross with shifting to the mechanism member is characterized in that it has a control means for varying slowly the speed command signal when shifting to and from the moving state and stopping state.

[Action]

That is, according to the speed servo control device for the mechanical member of the camera of the present invention, since the current position is detected by the integrating means and the switching timing of the speed command signal is controlled, it is not necessary to provide a position detecting sensor. It is possible to obtain a high accuracy, and even if the mechanism member is between the stopped state and the transition state, the change amount of the speed command signal at the time of mutual transition is moderated to cause an excess of the response capability of the servo system. Disturbance of the control characteristics is prevented. 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 addition / subtraction circuit in multiple stages. Or charging a capacitor connected in parallel with the above resistor
The speed command signal due to discharge is gently changed.

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
You. The speed servo control device of the mechanical member of the camera of the present invention is a diaphragm.
A shutter blade that doubles as a blade or a single shutter blade
May stop at any position such as the helicoid of the shooting lens.
Servo control device for mechanical members for cameras as required
Can be widely applied, but in the following, it can also be used as a diaphragm blade
Example in which the present invention is applied to a servo controller for a shutter blade
Will be explained. First, FIG. 1 is a photograph of a shutter mechanism to which the present invention is applied.
It is the figure seen from the 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 angular velocity can be controlled
It is a servo motor, and the output pin 12 of the servo motor M is
Data center 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 13 are also attached to the shafts 10b and 10c on the shutter base plate 10.
And shutter blades with at least the same blade shape rotate
It is freely supported, and the two shutter blades (not shown)
Engages with sector pins 11b and 11c, respectively, similar to chatter blade 13.
Since it is designed to swing,
When the sector ring 11 is rotated in the direction of arrow A, the shaft 10b ・ 1
Two shutter blades (not shown) supported by 0c each have an axis 10
Since it rotates counterclockwise around b and 10c, the aperture 11e
Start 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 blade 13 also shown in FIG.
The shutter mechanism that uses the (1) shutter blade 13 is closed
The shutter blade 13 opens when the chain is stopped.
The moving state, and (2) the shutter blade 13 is opened.
When the shutter blade 13 is at a constant F
Shift to the stopped state where the value is maintained, and (3) shutter blade
The shutter blades from the stopped state where the root 13 maintains a constant value
3 that the root 13 moves to a moving state in which it is in a closing motion
One exposure operation is performed depending on the type of state change. FIG. 2 shows a shutter mechanism as shown in FIG.
Servo control for driving by servo mechanism using
It is a block diagram showing the control device in principle, 20 is a speed command
Speed command generation circuit that generates a signal, A₃Is the speed command signal
Deviation amplifier that calculates the deviation of the current speed, M is the servo mode
, SA drives the servomotor M according to the speed deviation
Servo amplifier, G is tachogenerator, 21 is tachogenerator
Integration time that integrates the output of data G to generate a position signal
, 22 indicates that the output value of the integrating circuit 21 has reached a certain value.
Position detection circuit for detecting and, 23 controls the operation sequence
Each of the sequence circuits for performing 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 tachogenere
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 servomotor M is the tachogenerator.
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 tachogenerator G is the product
The time is integrated by the minute circuit 21,
The output is a mechanical member (book
In the embodiment, it indicates the position of the shutter blade 13).
Then, the position signal that is the output of the integrating circuit 21 becomes the preset value.
When the detection signal generated by the position detection circuit 22
Sequence circuit 23 switches the output of speed command generation circuit 20
Therefore, the speed command signal is controlled appropriately. 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. The characteristic points of this embodiment are (1) stop state
The opening operation is performed by shifting from the moving state to the moving state.
Sometimes the positive speed command signal is slowly increased, (2)
F value maintenance operation by shifting from the moving state to the stopped state
The speed command signal of plus is gradually reduced when operating.
(3) To move from the stopped state to the moving state again
The negative speed command signal is slowly
Maintains response response of mechanical members by increasing it
It is to control the speed command value within a possible range. 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 the servo amplifier SA composes._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 adjustment 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 V₆Is 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_FiveHas been added to the positive phase input of. 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 V₃Is added. Therefore,
Operational amplifier A_FourAnd operational amplifier A_FiveHas its output polarity reversed
It will be. And operational amplifier A_FourAnd operational amplifier A_Five
The output potential difference of the servo motor M as a drive voltage
Wide dynamic range of drive voltage because it is applied
can do. 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 tuning that causes the strobe to be issued
The circuit, 27 is, for example, a helicoid or an
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 sensitivity input that moves to generate a film sensitivity 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 A₂Rx for the positive phase input of
The voltage generated across the resistor Rx when the current Ix flows through
Iias voltage V₁The voltage superimposed on the
Follower A₂Since the output voltage of is equal to the positive phase input voltage,
Speed command signal V generated by the speed command generation circuit 20₂Is next
It is shown by (Formula 2). This speed command signal V₂Is the deviation amplifier A₃In addition to the normal phase input of
Deviation amplifier A₃Reverse-phase input resistance R_FourTachogenere
Current speed signal V generated by data G₆Is superimposed and added
Deviation amplifier A₃Velocity deviation signal V which is the output of₃
Is expressed 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_FiveIs
It is given by (Equation 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). The servo system as shown in Fig. 3 has a drive voltage of 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 3) into (Equation 7), the common term
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 shorted between the base and collector
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 switching transistor.
Transistor S, transistor D that functions as a diode, constant
It has a transistor T which functions as a current circuit. 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
The current is supplied from the transistor, and in the current switch Sd
Mutual connection of diode D and switching transistor S
The points are 6 transistors in the weighted current circuit 20c.
Current is being supplied. Therefore, each current switch Sb
The switching transistor S in Sc / Sd is conducting.
Sometimes, the weighting current circuit 20c is used to switch the current switches Sb and Sc
・ The current supplied to Sd is applied to the switching transistor S.
It passes and flows to the ground, but the switching transistor
When the switch S is cut off, the weighting current circuit 20c
The current supplied to the current switch Sb / Sc / Sd is a diode.
It flows to D. 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 V₂The value of is 2Rxi higher than when stopped. 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 indicated 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 pondhole 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 decreases corresponding to the current decrease. 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 will
The shutter blade 13 rotates at a speed proportional to
The speed decreases as shown in FIG. Then, as shown in Table 4, the 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 shutter 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 V₁It is 6 Rxi lower than that. 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. 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 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
Is the number of stages of the weighted current circuit 20c and the number of stages of current switches
To increase the current supplied to the resistor Rx in multiple stages.
May be used. Similarly, in the above, the shutter in the moving state is
When moving the blades to the stopped state and performing the F value maintaining operation
In order to reduce the current supplied to the resistor Rx in two steps,
Although an example is shown, this may also be set in multiple stages. Further, in the above, the present invention is applied to a diaphragm blade that also serves as a diaphragm blade.
Although an example used for controlling the opening and closing of the blade is shown, the present invention
In addition to this, the aperture position control of an independent diaphragm blade and automatic
Amount of helicoid of shooting lens in focus
It can also be used to control The present invention is suitable for controlling the aperture position of a single diaphragm blade.
When used, the comparators in Figs. 3 and 6
C₂Correspond the level of the reference power source 22b of
Data C₂It is detected that the output of is inverted to H level.
By shifting the moving state to the stopped state,
It is only necessary to maintain the F value,
The present invention is suitable for controlling the extension amount of the helicoid of the shadow lens.
When used, the comparators in Figs. 3 and 6
C₂The level of the reference power source 22b of the
Parator C₂It is detected that the output of
By issuing it, it will shift from the moving state to the stopped state and
It suffices to maintain a fixed focus position.

【effect】

As described above, according to the present invention, the speed command value can be gently changed when the mechanical member shifts from the stopped state to the moving state or vice versa. Even in the servo control of mechanical members for cameras that are greatly restricted by the power supply voltage and the torque capacity of the motor, the change amount of the speed command value rarely exceeds the response capability of the servo system, and the change amount of the command value is Disturbances in control characteristics caused by exceeding the corresponding capability are less likely to occur, and it becomes easier to obtain ideal control characteristics. Therefore, according to the present invention, it is possible to provide a position detecting device such as a potentiometer or a photoelectric encoder and obtain sufficient positioning accuracy without applying position servo. 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. Sufficient positioning accuracy can be obtained without the 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 (3)

(57) [Claims] 1. A speed command generating means for generating a speed command signal of a mechanical member driven by a servo actuator, the speed command generating means for generating a current speed signal of the mechanical member, the speed detecting means being provided in a camera. In the speed servo control device for the mechanical member of the camera, wherein the servo actuator drives the mechanical member corresponding to the deviation between the speed command signal and the current speed signal, the servo actuator temporally integrates the output of the speed detecting means. And a current adding / subtracting circuit having a plurality of current sources selectively used, and an output current of the current adding / subtracting circuit. A voltage converting means for converting into a voltage, and switching the output current of the current adding / subtracting circuit in response to the current position signal generated by the integrating means. And a control means for moving the speed command signal gently when the mechanical member makes a transition between the stopped state and the moving state, and when the mechanical member makes a transition between the stopped state and the moving state. The speed servo control device for the mechanical member of the camera. 2. A speed servo control device for a mechanical member of a camera according to claim 1, wherein the speed command generation means switches stepwise a plurality of current sources forming the current addition / subtraction circuit. A speed servo control device for a mechanical member of a camera, wherein a speed command signal is gently changed when the mechanical member transits between a stopped state and a moving state. 3. A speed servo control device for a mechanical member of a camera according to claim 1 or 2, wherein the voltage conversion means includes a resistance generated by the output current of the current adding / subtracting circuit. And a capacitor connected in parallel with the resistor, and when the mechanical member transitions between a stopped state and a moving state due to charging / discharging of the capacitor when switching the output current of the current adding / subtracting circuit. A speed servo control device for a mechanical member of a camera, characterized in that a speed command signal is gently changed.