JPS61295535A - Control circuit for voltage driven shutter - Google Patents

Abstract

PURPOSE:To perform an exposure operation from an invariably stable initial state without reference to an interval of photography by charging a member to be controlled in the opposite direction from the exposure operation after exposure seconds from the 2nd state of the exposure operation. CONSTITUTION:A voltage driven shutter performs the exposure operation by changing the member to be controlled which has electrostatic capacity from one electrostatic charging state to the other different-polarity charging state, ad electrostrictive elements 51 and 52 are charged when a shutter button is pressed by a half stroke, when the shutter button is pressed by its full stroke, or when proper exposure is obtained; and a pulse generated by a one-shot circuit 53 in said cases is applied to transistors TR1, TR2, TR3, and TR4 through some of NAND gates G1, G2, G3, and G4 to turn on and off the TR1, TR2, TR3, and TR4 successively according to the charging states of the electrostrictive elements 51 and 52 at the end of last photography and the progress of a photographic sequence.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a control circuit for a voltage-driven shutter, and more specifically, the present invention relates to a control circuit for a voltage-driven shutter, and more specifically, for example, a light-shielding member is opened and closed using mechanical distortion generated in an electrostrictive element having a bimorph structure as a driving force source when a voltage is applied to the electrostrictive element. A shutter mechanism that performs exposure operation and a PLZ layered with a polarization grating.
For a voltage-driven shutter that performs exposure operation by rotation of the polarization axis that occurs when a voltage is applied to the T-plate, it is possible to apply a voltage from the negative region to the positive region for the purpose of, for example, lowering the absolute value of the applied voltage. In the control circuit of the voltage-driven shutter, in the first stage of the exposure operation, a voltage corresponding to the initial position is applied, and then a voltage that enables the exposure operation is applied, thereby achieving stable exposure regardless of the shooting interval. The present invention relates to a control circuit for a voltage-driven shutter that can provide a voltage-driven shutter.

[Conventional technology]

For example, as an example of a voltage-driven shutter, a shutter mechanism has already been developed that opens and closes a light-shielding curtain using the mechanical distortion generated in the electrostrictive element having a bimorph structure as a driving force source when a voltage is applied to the electrostrictive element. ing. First, to explain the operating principle of an electrostrictive element with a bimorph structure, an electrostrictive element has a structure in which ceramic layers having a piezoelectric effect are laminated on both sides of a thin metal piece.One end of the electrostrictive element is fixed and a voltage is applied to both ceramic layers. When applied, its free end has the property of being distorted. Since the electrostrictive element acts equivalently to a capacitor in terms of circuitry, once it is charged, it retains the charge and maintains its distorted state even after electricity is cut off. By utilizing the distortion that occurs at the free end of this electrostrictive element when a voltage is applied to it, the electrostrictive element can be used as a source of mechanical driving force. The amount of distortion that occurs at the free end of the electrostrictive element when a voltage is applied to the electrostrictive element of the ridge structure is the amount of distortion that occurs at the free end of the electrostrictive element when other conditions (for example, the length, thickness, piezoelectric constant, etc. of the electrostrictive element) are constant. , proportional to the applied voltage. Therefore, in order to sufficiently increase the amount of distortion generated at the free end of the electrostrictive element, it is desired to increase the absolute value of the applied voltage, but when the absolute value of the applied voltage is increased,
(L) Since the amount of distortion per unit length of the electrostrictive element increases, there is a risk that the element will be destroyed. (2) The power conversion efficiency of the high voltage inverter decreases. There are other problems. Therefore, a control method has been developed in which the electrostrictive element is distorted in both positive and negative directions by applying a voltage from a negative region to a positive region to the electrostrictive element, thereby increasing the amount of displacement as a whole without increasing the amount of distortion. has also been proposed. Now, when driving, for example, a focal plane shutter using distortion generated in such an electrostrictive element, an electrostrictive element is provided in each drive system of the front curtain and the rear curtain, and in the nth exposure operation, For example, from a state in which both electrostrictive elements are negatively charged, the electrostrictive element that drives the leading curtain is charged positively, and after a delay time corresponding to the exposure time, the electrostrictive element that drives the trailing curtain is charged positively. By charging, proper exposure can be obtained, and in the subsequent (n+1)th exposure operation, the front curtain (the rear curtain at the nth exposure operation) is driven from a state in which both electrostrictive elements are positively charged. If the electrostrictive element that drives the rear curtain (the leading curtain at the n-th exposure operation) is negatively charged after a delay time corresponding to the exposure seconds after negatively charging the electrostrictive element that drives the rear curtain (the leading curtain at the n-th exposure operation),
Proper exposure can be obtained.

[Problems to be solved by the invention]

Now, this method of distorting the electrostrictive element in both positive and negative directions is extremely effective in that it can reduce the absolute amount of distortion while ensuring a sufficient amount of displacement. Still, there are problems as described below. That is, in the above method, the electrostrictive element is initially charged to a certain polarity, and the exposure operation is performed by charging the electrostrictive element to the opposite polarity in conjunction with the ON operation of the shutter switch. The initial position of the shirt shutter curtain may be determined in accordance with the potential of the electrostrictive element in the initial state. Therefore, even if the electrostrictive element acts equivalently to a capacitor with extremely large capacitance, the initial potential will fluctuate due to natural discharge unless the imaging interval is always constant.
The initial position of the shutter curtain may also change, which may cause exposure errors or partial curtain breaks. Similar problems are not limited to shutter mechanisms in which a focal plane shutter is driven by an electrostrictive element, but also when a controlled target member with capacitance is changed from one charged state to another charged state with a different polarity. This applies to all shutter mechanisms that perform exposure operations.

[Means to solve the problem]

The present invention was made in view of these problems, and
It is an object of the present invention to provide a control circuit for a voltage-driven shutter that can always perform an exposure operation from a stable initial state regardless of the length of the photographing interval. In summary, the voltage-driven shutter control circuit of the present invention has the following features:
゛Basically, in a voltage-driven shutter in which an exposure operation is performed by changing a controlled object having a capacitance from one charged state to another charged state with a different polarity,
a first means for charging the controlled object member in a direction opposite to the original exposure operation in a first stage of the exposure operation;
and a second means for charging the controlled object member in the direction of the original exposure operation in the exposure operation, and the first means charges the controlled object member in the exposure operation after an exposure time from the second stage of the exposure operation. It is designed to charge in the opposite direction. In addition, in particular, in the case of a shutter mechanism that includes a controlled object member for front curtain operation and a controlled object member for rear curtain operation, each having a capacitance, such as a focal brain shutter, the means for charging the inner controlled object member in a direction opposite to the original exposure direction in one step; and means for charging the front curtain operation controlled object member in the direction of opening the aperture in a second step of the exposure operation; and means for charging the controlled object member for rear curtain operation in the closing direction of the aba-dure after an exposure time from the second stage.

[Effect]

Therefore, according to the present invention, since it is possible to execute the exposure operation after reliably positioning the member to be controlled in the first stage of the exposure operation, the difference in the initial potential due to the length of the shooting interval This makes it possible to effectively prevent exposure errors and the occurrence of unexposed portions.

【Example】

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. First, FIG. 1 is a view of an example of a mechanism in which a focal brain shutter is driven by an electrostrictive element having a bimorph structure, as viewed from the photographic lens side. Note that the focal plane shutter shown in Figure 1 is
Although an example is shown in which each of the rear curtains is composed of two blades, the number of blades is not an essential requirement for the present invention. In FIG. 1, reference numeral 10 indicates a shutter base plate on which a shutter mechanism is mounted, and an aperture lOa is bored approximately in the center of the shutter base plate 10. In addition, in the figure, 11, 12, 13, and I4 each indicate a shank blade, and each shutter blade 11, 12, 13, and 14 are the first shank blades.
In the state shown in the figure, the shutter blades 11 and 12 constitute a front curtain, the shutter blades 13 and 14 constitute a rear curtain, and the aperture 10a is shielded by the shutter blades 11 and 12. ing. The shutter blades 11 and 12 open and close the aperture 10a in conjunction with the rotational movement of the blade arms 15 and 16, and similarly, the shutter blades 13 and 14 open and close the aperture 10a in conjunction with the rotational movement of the blade arms 17 and 18. It is done as follows. First, the fixed ends of the blade arms 15 and 16 are rotatably supported by shafts I9 and 20, respectively, which protrude toward the photographing lens near the left side of the shutter base plate 10, and the blade arms 15 and 16 are rotatably supported at their substantially intermediate portions. It is curved in the shape of a ``. The shutter blade 11 is rotatably supported (rotation crimped) on shafts 21 and 22 provided at curved portions of the blade arms 15 and 16. Virtual line segment connecting the centers of axes 19 and 20 and axes 21 and 22
The virtual line segments connecting the centers of are parallel, and the axes 19 and
Since the virtual line segment connecting the centers of 21 and the virtual line segment connecting the centers of the shafts 20 and 22 are parallel, if the blade arm 15 is rotated around the shaft 19, The blade arm 16 also rotates, and the shafter blade 1 moves up and down while maintaining a horizontal state in FIG. In addition, the shaft 2 provided at the tip of the blade arms 15 and 16
The shutter blade 12 is rotatably supported (rotation crimped) at 3 and 24. Then, the virtual line segment connecting the centers of axes 23 and 24 is also axis 1.
Since it is parallel to the virtual line segment connecting the centers of 9 and 20,
The shutter blade 12 moves vertically in parallel with the shutter blade 11, and the more the shutter blades 11 and 12 move downward in FIG. 1, the larger the combined area of the shutter blades 11 and 12 becomes. Similarly, the fixed ends of the blade arms 17 and 18 are rotatably supported by shafts 27 and 28, respectively, which protrude from near the left side of the shutter base plate 10 toward the photographing lens, and the blade arms 17 and 18 are rotatably supported at their substantially intermediate portions. It is curved in the shape of a "<". The shutter blade 13 is rotatably supported (rotation crimped) on shafts 29 and 30 provided at curved portions of the blade arms 17 and 18. Then, a virtual line segment connecting the centers of axes 27 and 28 and axis 2
The virtual line segments connecting the centers of 9 and 30 are parallel, and
Virtual line segment connecting the centers of axes 27 and 29 and axes 28 and 30
Since the virtual line segments connecting the centers of are parallel, if the blade arm 18 is rotated around the shaft 28, the blade arm 17 will also rotate in conjunction with this, and the shutter blade 13 will also rotate as shown in FIG. It will move up and down while maintaining a horizontal state. In addition, the shaft 3 provided at the tip of the blade arms 17 and 18
1 and 32, the shaft blade 14 is rotatably supported (rotationally caulked). Then, the virtual line segment connecting the centers of axes 31 and 32 is also axis 2.
Since it is parallel to the virtual line segment connecting the centers of 7 and 28,
The shutter blade 14 moves vertically in parallel with the shutter blade 13, and the more the shutter blades 13 and 14 move upward in FIG. 1, the larger the combined area of the shutter blades 13 and 14 becomes. Note that 25 and 26 are blade arm stoppers that protrude from the shutter base plate 10 toward the photographic lens side. The contact portion 15a of the blade arm 15 and the contact portion 17a at the tip of the branch arm of the blade arm 17 contact the blade arm stopper 25 to prevent counterclockwise rotation of the blade arm 15 and the blade arm 17. The abutting portion 16a at the tip of the branched arm of the vane arm 16 and the abutting portion 18a of the vane arm 18 abut against the vane arm stopper 26 to prevent clockwise rotation of the vane arm 16 and the vane arm 18. Now, the shutter mechanism shown in FIG. 1 moves the shutter blades 11 and 12 upward by rotating the blade arms 15 and 16 counterclockwise when the state shown in FIG. 1 is the initial state. After starting the exposure operation, the shutter blades 13 and 14 are rotated counterclockwise by rotating the blade arms 17 and 1 with a time difference corresponding to the exposure time.
By moving upward, one exposure operation can be performed. Furthermore, if the initial state is such that one exposure operation is completed and the shutter blades 11, 12, 13, and 14 have all moved upward, the blade arms 17 and 18 are rotated clockwise. After the shutter blades 3 and 14 are moved downward to start the exposure operation, the shutter blades 11 and 12 are rotated clockwise by rotating the blade arms 15 and 16 with a time difference corresponding to the exposure time. By moving downward, the next exposure operation can be performed. In this embodiment, the blade arms 15 and 18 are rotated using the distortion generated at the free end of the piezoelectric electrostrictive element when a voltage is applied to the element as a driving force source. Specifically, 50 is an insulating electrostrictive element holding member;
One end of the electrostrictive elements 51 and 52 is fixed to the shutter base plate 10 via the electrostrictive element holding member 50. Further, 33 indicates an interlocking lever for transmitting distortion at the free end of the electrostrictive element 51 to the blade arm 15, and the interlocking lever 33 is rotatable on a shaft 34 protruding from the shutter base plate 10 toward the photographing lens side. is supported by An interlocking lever drive member 3 is provided at the tip of the electrostrictive element 51.
5 is fixed, and a bifurcated pawl 35a at the tip of the interlocking lever drive member 35 engages with a boss 33a formed at the tip of the driving arm of the interlocking lever 33, thereby controlling the amount and direction of distortion of the electrostrictive element 51. The interlocking lever 33 is designed to rotate in response to the movement. Further, near the shaft 19 of the vane arm 15, a boss 15b projects toward the photographing lens 1, and this boss 15b engages with a bifurcated pawl 33b at the tip of the driven arm of the interlocking lever 33. Therefore, when the tip of the electrostrictive element 51 is distorted upward in FIG. Move the blades 11 and 12 downward. Similarly, 36 indicates an interlocking lever for transmitting distortion at the free end of the electrostrictive element 52 to the blade arm 18, and the interlocking lever 3G is rotatable on a shaft 37 protruding from the shutter base plate 10 toward the photographing lens side. is supported by An interlocking lever drive member 3 is provided at the tip of the electrostrictive element 52.
8 is fixed, and a bifurcated pawl 38a at the tip of the interlocking lever drive member 38 engages with a boss 36a formed at the tip of the driving arm of the interlocking lever 36, thereby controlling the amount and direction of distortion of the electrostrictive element 52. The interlocking lever 36 is configured to rotate in response to this. Further, near the shaft 28 of the vane arm 18, a boss 18b projects toward the photographic lens side, and this boss 18b engages with a bifurcated pawl 36b at the tip of the driven arm of the interlocking lever 36. Therefore, when the tip of the electrostrictive element 52 is bent upward in FIG. Move the wings tli13 and 14 downward. In FIG. 1, the free ends of the electrostrictive elements 51 and 52 are bent upward due to the accumulated charge, and the shack blade 1
1 and 12 show the state in which the aperture 10a is closed. By the way, in the case of the shutter with the ridge structure, the shutter blade 1
Needless to say, the initial positions of 1, 12, 13, and 14 are determined by the amount of electricity accumulated in the vane arm stoppers 25, 26 and the electrostrictive elements 51, 52. Electrostrictive element 5
The amount of charge accumulated in 1.52 varies depending on the natural discharge that accompanies the passage of time since the end of the previous photographing. Therefore, in the present invention, the electrostrictive elements 51 and 52 are
In order to prevent exposure errors and partial termination due to fluctuations in the amount of initial charge, the actual shirt release operation is performed after a stable initial charge is charged in the first stage of shirt release. The direction in which the electrostrictive elements 51 and 52 are charged with initial charges varies depending on the charging direction of the electrostrictive elements 51 and 52 at the end of the previous shooting, and after the electrostrictive elements 51 and 52 are fully charged in the same direction as the charging direction at the end of the previous shooting. It is required to begin the exposure operation. Therefore, in this embodiment, means is provided for storing the charging direction of the electrostrictive elements 51 and 52 at the end of the previous photographing, and the charging direction and charging order of the electrostrictive elements 51 and 52 are controlled. Therefore, an example of a circuit for carrying out the above-mentioned control operation will be explained next with reference to FIG. Although the digital circuit in FIG. 2 is shown with positive logic for both input and output, this is to facilitate understanding of the embodiment, and the positive and negative logic expressions are essential to the present invention. Needless to say, this is not a necessary requirement. First, in FIG. 2, numerals 51 and 52 are the electrostrictive elements already explained in FIG. 1, and the electrostrictive elements 51 and 52 are equivalent to capacitors in circuit terms. In this embodiment, the electrostrictive elements 51 and 52 are both connected to the second
The left electrode in the figure is positively charged, causing the first
In the figure, the free end is bent upward and the second
By positively charging the electrode on the right side of the figure, its free end is bent downward in FIG. In the following, it is assumed that the electrodes on the left side of the electrostrictive elements 51 and 52 in FIG. 2 are positively charged.
It is expressed that the electrostrictive elements 51 and 52 are positively charged, and that the left electrode of the electrostrictive elements 51 and 52 in FIG.
・It is expressed that 52 is negatively charged. Also, Pl ・F2・F3・F4 ・F5・F6・F7・
Po is a photocoupler, and photocoupler P,・F2・
F3 ・F4 ・F5 ・F6 ・F7 ・Photodiode D1 on the 2nd ・F2 ・F3 ・F4 ・F5
・F6 ・F7 ・F8 and photothyristor S, ・S2
・S3 ・G4 ・S5 ・G6 ・G7 ・G8. Then, the electrostrictive element 51 includes photo-siliks S2 and S3.
When G4 is in the off state, the photothyristor s1 becomes positively charged, and when G4 is in the off state, the photothyristor s1 becomes photothyristor S2.
・When G3 is turned on, it becomes negatively charged. Similarly, the electrostrictive element 52 is a photoresist S6/S
When 7 is in the off state, the photothyristor S5 is positively charged when 8 is in the on state, and photothyristor s5 is activated. When Se is in the off state, the photothyristor s
6 - When G7 is turned on, it becomes negatively charged. Further, TR, TR2, TR3, and TR4 respectively indicate switching transistors, among which transistors TR,
is the photodiode D1 and F4, and the transistor TR
2 is the photodiode D2/F3, and the transistor TR
3 is the photodiode D5/F8, and the transistor T
R4 is for causing each of the photodiodes D6 and F7 to emit light. In this embodiment, transistors TR, ・TR2・T
The gate circuit group arranged before R3 and TR4 regulates the operating order of the transistors TR, TR2, TR3, and TR4, so that the charging direction and charging order of the electrostrictive elements 51 and 52 are regulated. There is. More specifically, the charging operation of the electrostrictive elements 51 and 52 is performed at (1) a timing when a shutter button (not shown) is half stroked, and (2) a timing when a shutter button (not shown) is full stroked. , (3) This is the timing when proper exposure is obtained, and at each of the above timings, the pulses generated by the one-shot circuit 53 are connected to the AND gate G.
1. Transistor TR via any one of G2, G3, and G4, and transistor TR in addition to TR2, TR3, and TR4. - TR2, TR3, and TR4 are turned on sequentially in accordance with the state of charge of the electrostrictive elements 51 and 52 at the end of the previous shooting and the progress of the shooting sequence. The state of charge of the electrostrictive elements 51 and 52 at the end of the previous shooting and the progress of the shooting sequence are determined by the flip-flop F1.
・Reflected as F2/F3 status. First, the flip-flop Fl is used to store the charging direction of the electrostrictive elements 51 and 52 at the end of the previous photographing, and its R input has the down edge of the pulse passed through the OR gate G5 inverted by the inverter gate G6. A pulse generated by the one-shot circuit 54 is applied to the S input of the flip-flop F1 using the signal as a trigger, and a one-shot circuit is applied using the signal obtained by inverting the down edge of the pulse that has passed through the AND gate G4 as a trigger. 55 is applied. Then, at the end of the previous shooting, the electrostrictive elements 51 and 5
2 is positively charged, the last pulse generated by the one-shot circuit 53 passes through the OR gate G5, so the flip-flop F1 is reset, and the output of the flip-flop F1 causes the AND gate 0.G9
・GIO becomes effective. Conversely, at the end of the previous shooting, the electrostrictive elements 51 and 52
When is negatively charged, the last pulse generated by the one-shot circuit 53 passes through the AND gate G4, so the flip-flop F1 is set, and the C output of the flip-flop F1 causes the AND gates Gll, GI2, and
CtS becomes effective. Next, flip-flop F2 and flip-flop F
3 is for storing the progress state of the photographing sequence. First, the second release signal R3, generated during the half stroke of the shutter button, is applied to the S inputs of the flip-flops F2 and F3, and the second release signal R3, generated during the full stroke of the shutter button, is applied to the R input of the flip-flop F2.
A release signal RS2 is applied via an AND gate G21, and a pulse generated by a one-shot circuit 56 is applied to the R input of the flip-flop F3 at the timing when proper exposure is obtained. Then, the C output of the flip-flop F2 is sent to the AND gate Ge-GII, and the C output of the flip-flop F2 and the C output of the flip-flop F3 are sent to the AND gate GI4.
The output of flip-flop F3 is AND gate G13.
It has been added to GIO. Therefore, when the free knob flop F2 is set by the Lurys signal R31, the AND gate Ga.GI
When the output of one of I (selected depending on the status of flip-flop F1, the same applies hereinafter) becomes H level, and then flip-flop F2 is reset by the second release signal R82 (at this point, Since flip-flop F3 is set.) The output of AND gate G14 becomes H level and AND gate G9
- When one of the outputs of GI2 becomes I (level), the one-shot circuit 56 responds to the output of the exposure control device 57.
When the flip-flop F3 is reset by the pulse output by the AND gate 010 or CtS, the output of one of the AND gates 010 and CtS becomes H level. And the output of AND gate G8 is OR gate GI8.
The output of the AND gate Gs is sent to the AND gate G2 via the OR gate G17, and the output of the AND gate GIO is sent to the AND gate G4 via the OR gate GI9.
The output of AND gate G17 and G19 is sent to AND gate G2 and G4, the output of AND gate G and G2 is sent to AND gate G3 via G+s, and the output of AND gate GI3 is sent to AND gate G3 via OR gate G16. and gates Gt, respectively, and are designed to control the opening and closing of these AND gates GI-G2, G3, and G4. Note that 57 is a known exposure control device. Specifically, the exposure control device 57 includes a capacitor 57a that integrates subject light, a 5PD57b that supplies an integral current corresponding to the subject brightness to the capacitor 57a, and a reference power source 57c.
, a comparator 57d1 that compares the integrated value of the capacitor 57a with the level of the reference power source 57c, and a transistor 57e for auto triggering.When the transistor 57e is cut off, the capacitor 57a integrates the photocurrent flowing to the 5PD57b, and the integrated value is When the value reaches the level set by the reference power supply 57C, the output of the comparator 57d is inverted, and the one-shot circuit 56
is set so that it is triggered. Also, 58 is a buffer that initializes the entire system when the power is turned on.
This is a power-up clear circuit. Next, the operation of this embodiment will be explained with reference to the above matters and the time chart shown in FIG. First, when the power is turned on, the power-up clear circuit 5
8 generates a clear pulse, and the flip-flops F1, F2, and F3 are all cleared by this clear pulse. Also, since this clear pulse is applied to the bases of the transistors TR+ and TR3 via Gs and GI5, the transistors TR1 and TR3 are conductive for the on time of the clear pulse, and during that time the light emitting diodes D1, D4 and D5 are turned on.・D8 emits light. At this time, the pulse generated by the one-shot circuit 54 at the timing of the down edge of the pulse that has passed through the OR gate G5 is applied to the R input of the flip-flop F1, so the flip-flop F maintains its reset state and its output AND gates Gθ, G9, and GIO become valid. When the light emitting diodes D and D4 emit light, the photothyrist S1 and S4 are turned on, and the power supply ■1■ - the photothyristor S1 - the electrostrictive element 51 - the photothyrist S4
- A series circuit called ground is formed, and the light emitting diode t' D s ・D8 similarly emits light, so that the photothyrist S5 ・Ss is turned on, and the power supply Vl+ − photothyristor S4 − electrostrictive element 52 − photothyrist Since a series circuit called 8-day Nibrand is formed, the electrostrictive elements 51 and 52 are both positively charged, and their free ends are distorted upward in FIG. First, when the free end of the electrostrictive element 51 is distorted upward in FIG. Since the blade arm I6 also rotates clockwise in conjunction with this, the shutter blades 11 and 12 close the aperture 10a while moving downward. When the electrostrictive element 51 is fully charged, the abutting portion 16a at the tip of the branch arm of the vane arm 16 abuts against the vane arm stop collar 26, and the shafter vane 11/work 2 is stopped at that position. Similarly, when the free end of the electrostrictive element 52 is bent upward in FIG. 1, the interlocking lever drive member 38 rotates the interlocking lever 36 counterclockwise, causing the vane arm 18 to rotate clockwise. In conjunction with this, the blade arm 17 also rotates clockwise, so the shutter blades 13 and 14 move downward and become folded. When the electrostrictive element 52 is fully charged, the contact portion 18a of the blade arm 18 is pressed against the blade arm stopper 26.
The shutter blades 13 and 14 stop at that position. By the way, in this embodiment, the electrostrictive elements 51 and 52 are charged via the photothyristors S1, S4, Ss, and Sa, respectively, so as the charging level of the electrostrictive elements 51 and 52 increases, the photothyristors S1° and S4・Ss ・S8
When the current flowing through the photothyristor S+ decreases, the photothyristor S+
-5s, Ss, and Sa automatically turn off, but the electrostrictive elements 51 and 52 continue to be charged and maintain the distorted state. As described above, the electrostrictive elements 51 and 52 accumulate charges and maintain a distorted state even after the photothyristor Sl-54, Ss, and Sa are turned off, but if this state continues for a long time, The accumulated charge is gradually discharged naturally, and the amount of distortion is also reduced. Therefore, in this embodiment, when the photographer presses the shutter button, the electrostrictive elements 51 and 52 are fully charged again in the charging direction during the half stroke of the shutter button.
By performing an actual exposure operation, it is possible to prevent exposure errors due to differences in initial charges. Electrostrictive elements 51 and 52 at the time of shafter release operation
The charging direction of is indicated by the state of flip-flop F1. Before the first photograph is taken, the flip-flop Fl remains in the initially cleared state, and one input of the AND gate GB-G9 and CIO is at the 11 level due to its output. When the shutter button is pressed to take the first picture after the power is turned on, the flip-flop F
2 - Flip flop F3 are both cents. Then, when the flip-flop F2 is turned on, the output of the AND gate on day 0 becomes H level due to its Q output. The level output of this ant game) 0 is applied to the AND gate G1 via the OR gate G16 to enable the AND gate G1 to conduct, and is also applied to the Ant game) G3 via the OR gates G and 8. Enables conduction of GK. Therefore, the pulse generated by the one shot 53 triggered by the first Luries signal R3+ is applied to the transistor TR+ via the AND gate G1-Gl and the OR gate G5, and is also applied to the AND gate G3 and the OR gate G1.
5 to the transistor TR3. Therefore, transistor TRI and transistor TR3
is conductive during the on-time of the pulse, so that the electrostrictive elements 51 and 52 are once again positively charged, and the shutter blades 11, 12, 13, and 14 are positioned at their correct initial positions, as described above. Subsequently, when the shutter button is fully stroked, the second
A release signal R32 is generated, and this second release signal R32 is generated.
82 is added to AND gate G21. The output of AND gate G22 is applied to the other input of AND gate G21, but at this point, flip-flop F3
is set and its Q output is at 1 lebel, and
After the one-shot circuit 53 generates a pulse, the output of the inverter gate G23 is also at the H level, so the output of the AND gate G22 is at the H level, and therefore the second release signal R32 outputs the ant gate G2+. passes through and resets flip-flop F2. By resetting the flip-flop F2, the output of the AND gate G14 becomes 1 (level), so the output of the AND gate G9 also becomes H level, which causes the OR gate G1
7 to AND gate G2, enabling AND gate G2 to conduct. Therefore, the pulse generated by the one-shot circuit 53 triggered by the second release signal passes through the AND gate G2 and is applied to the transistor TR2, so that the transistor TR2 conducts during the ON time of the pulse, and the photodiode D2 and the photodiode D3 emits light during that time, and photothyristor S2 and photothyrisk S3 are turned on during that time. Therefore, a series circuit of power supply Vll, photothyristor S3, electrostrictive element 5, knee photothyristor S2, and ground is formed, and the electrostrictive element 51 is negatively charged. When the electrostrictive element 51 is negatively charged, its free end is bent downward in FIG. The vane arm 15 rotates counterclockwise. In conjunction with this, the blade arm 16 also rotates counterclockwise, so the shutter blades 11 and I2 open the aperture 10a while moving upward, and the exposure operation is started. Then, when the electrostrictive element 51 is fully charged negatively, the contact portion 15a of the blade arm 15 contacts the blade arm stopper 25, and the shutter blades 11 and 12 are stopped at that position. On the other hand, since the auto-trigger transistor 57e is cut off due to the reset of the flip-flop F2 described above, the integrating capacitor 57a starts integrating the photocurrent flowing to the 5PD57b at the same time as the exposure operation starts. There is. Then, when the integrated value of the capacitor 57a reaches the level of the reference power supply 57C, the output of the comparator 57d rises, and the one-shot circuit 56 generates a pulse at the up edge, and this pulse causes the flip-flop F3
will be reset. When the flip-flop F3 is reset in this manner, the output of the AND gate GIo becomes I (level), which is transmitted to the AND gate G4 via the OR gate G19, thereby enabling the AND gate G4 to conduct. Therefore, the pulse generated by the one-shot circuit 53 triggered by the pulse generated by the one-shot circuit 56 passes through the AND gate G4 and is applied to the transistor TR4. Accordingly, transistor TR4 conducts during the on-time of the pulse, so that photodiode D6 and photodiode D7 emit light during that period, and photothyrist S6 and photothyristor S7 are turned on during that period. Therefore, a series circuit of power supply VH, phor, thyristor S7, electrostrictive element 52, photothyristor S6, and ground is formed, and electrostrictive element 52 is negatively charged. When the electrostrictive element 52 is negatively charged, its free end is bent downward in FIG. 1 and the interlocking lever 36 rotates clockwise, causing the vane arm 18 to rotate counterclockwise. In conjunction with this, the blade arm 17 also rotates counterclockwise, so the shutter blades 13 and 14 move upward to close the aperture 10a and complete the exposure operation. When the electrostrictive element 52 is fully negatively charged, the contact portion 17a at the tip of the branch arm of the blade arm 17 contacts the blade arm stopper 25, causing the shutter blades 13 and 14 to contact the blade arm stopper 25.
will stop at that position. Also, at this time, the flip-flop F1 is driven by a pulse generated by the one-shot circuit 55 at the down edge of the pulse that has passed through the AND gate G4. In this manner, at the end of the first (odd-numbered) exposure operation, the shutter mechanism has the shutter blades 11 and 12 retracted above the aperture 10a, contrary to the state shown in FIG. The blades 13 and 14 are in a state of closing the aperture 10a, and in the next even-numbered exposure operation, the shutter blades 13 and I4 travel downward to start the exposure operation, and then the shutter blades 11 and 12 travel downward. Ends the exposure operation. To explain the specific operation of the circuit system, first, at the end of the odd-numbered exposure operation, the flip-flop F1
is set, and depending on the Q output
One of the inputs of Go, G12, and G13 is at I] level, and the AND gate Gll, G12, and a+3 becomes valid. Furthermore, the flip-flop F2 and the flip-flop F3 are each reset by the second release signal R52 and the pulse generated by the one-shot circuit 56 in the previous (odd-numbered) exposure operation. When the flip-flop F2 is set by the Lullies signal R51 in the even-numbered shooting, the output of the AND gate GII becomes H level due to its Q output, and this is sent to the AND gates G2 and G4 via the OR gates G17, G, and 9. communicated. Therefore, the pulse generated by the one-shot circuit 53 using the first Lurie's signal R5 as a trigger is the AND gate G2.
4 and makes the transistors TR2 and TR4 conductive, so the electrostrictive elements 51 and 52 are both negatively charged in the same manner as above, and the shutter blades 11, I2, 13, and 14 are returned to their initial positions (see Fig. 1). (in the opposite position). When the flip-flop F2 is reset by the subsequent second release signal R52, the output of the AND gate GI2 becomes I via the AND gate GI4.
(This level is transmitted to the AND gate G3 via the OR gate G+e. Therefore, the pulse generated by the one-shot circuit 53 triggered by the second release signal R32 is the AND gate G3-
Since the light passes through the OR gate G15 and makes the transistor TR3 conductive, the free end of the electrostrictive element 52 is distorted upward in FIG. 1, the shutter blades 13 and 14 move downward, and the exposure operation is started. Thereafter, when the flip-flop F3 is reset by a pulse generated by the one-shot circuit 56 at the timing when proper exposure is given, the output of the AND gate G13 becomes H level, and this is passed through the OR gate G16. It is transmitted to AND gate G1. Therefore, the pulse generated by the one-shot circuit 53 triggered by the pulse generated by the one-shot circuit 56 makes the transistor TR conductive via the AND gate G1 and the OR gate G5, so that the free end of the electrostrictive element 51 becomes the first
In the figure, the shutter blade is distorted upward.Shutter blade 1
1 and 12 travel downward to complete the exposure operation. Then, the flip-flop F1 is reset by a pulse generated by the one-shot circuit 54 at the down edge of the pulse that has passed through the OR gate G5, and prepares for the next odd-numbered photographing. After that, repeat the above operation alternately, repeating the odd-numbered
Even numbered shots are taken. Although the above description assumes a still camera using a normal photosensitive material, in the case of a so-called electronic still camera, the second release signal may be replaced with a vertical synchronization signal. Moreover, in the above, the electrostrictive elements 51 and 5 are in a positively charged state.
The electrostrictive elements 52 and 51 are negatively charged by performing an odd-numbered exposure operation by sequentially charging the electrostrictive elements 52 and 51.
We have shown an example in which the exposure operation is performed when the shutter blade moves in both directions, such as sequentially positively charging the shutter blades to perform the even-numbered exposure operation. In addition to the above, the focal plane shutter can also be used, for example, after performing an exposure operation by sequentially negatively charging the electrostrictive elements 51 and 52 that are in a positively charged state.
Electrostrictive element 51 without opening aperture 10a.
- There is also an example in which the initial state is returned by positively charging the electrostrictive element 52 again, and by applying the present invention to such cases, the initial potential of the electrostrictive element can be stabilized. In this case, the flip-flop F for storing the charging state of the electrostrictive element and the gate circuit attached thereto become unnecessary, and the shutter blade 13 serving as the rear curtain becomes unnecessary.
means for triggering the one-shot circuit 53 at the timing when 14 closes the aperture, and the pulse generated by the one-shot circuit 53 at this time is transmitted to the transistor TRI.
A means for transmitting the charge to the transistor TR3 and positively charging the electrostrictive elements 51 and 52 again is required. Furthermore, as an example of a voltage-driven shutter, an example in which the present invention is applied to a shutter mechanism using distortion generated when a voltage is applied to an electrostrictive element as a driving force source was shown above. It can equally be applied to a shutter mechanism that is driven by applying a voltage to a member to be controlled. For example, an electro-optic ceramic whose polarization axis rotates in response to the applied voltage is laminated with a polarizing plate. The present invention can also be applied to the control of so-called PL rashers. FIG. 4 is an exploded perspective view showing the basic structure of the PL Rashata.
As an example, the PLZT plate 62 is used as an example, and the light that passes through the photographic lens is polarized by the polarizing plate 60, and the P i, Z T plate 62
The light passes through and enters the polarizing plate 61. When the PLZT plate 62 receives all 62 light and applies a voltage from the drive circuit 63 in a direction perpendicular to the incident light, it has the property of rotating the polarization axis of the incident light in response to the applied voltage. Therefore, for example, if we consider the case where the polarizing plates 60 and 61 are arranged so that their polarization axes are perpendicular to each other as shown by the arrows a and 61, first, when all the PLZT plates 62 are not applied The light polarized by the polarizing plate 60 passes through the PLZT plate 62 and enters the second polarizing plate 61 as it is, but the polarization axes of the second polarizing plate 61 are arranged orthogonally in advance as shown by the arrows. Therefore, it is blocked by the second polarizing plate 61. On the other hand, when a voltage is applied to rotate all 62 axes of the PLZT plate 62 by 90 degrees, the polarization axis of the light polarized by the first polarizing plate 60 will be 90 degrees when all 62 axes of the PLZT plate 62 are rotated.
rotated to become parallel to the polarization axis of the second polarizing plate 61,
It will pass through the second polarizing plate 61. Therefore, in the case of the PL Rashata with the above structure, the PLZT plate 6
By simply controlling the time during which the above-mentioned voltages are applied, it is possible to achieve a high-speed shutter that cannot be achieved with a mechanical shutter mechanism. Figure 5 shows P in which the polarization axes of polarizing plates 60 and 61 are orthogonally arranged.
This shows an example of the relationship between the applied voltage Vll and the transmittance σ of incident light for all 62 PLZT plates 62 in the L rashata. When the applied voltage VII=O, the transmittance σ becomes 0, and when the applied voltage 1 =E (E is the voltage that rotates the polarization axis by 90 degrees), the transmittance becomes maximum. Now, the PL rays of this product structure can be determined by determining the crossing angle of the polarization axes of the polarizing plates 6° and 61, so that the transmittance σ
The applied voltage when becomes 0 can be determined. For example, if the polarizing axis of the polarizing plate 6■ is aligned with the polarizing axis of the polarizing plate 6o and tilted upward by +45 degrees as shown by arrows a and C in FIG. 4, as shown in FIG. PLZT board 62 total 6
When the applied voltage for 2 is 11/2E, the polarization axis of the light that has passed through the polarizing plate 60 is rotated 45 degrees counterclockwise through the entire PLZT plate 62, and is perpendicular to the polarization axis of the polarizing plate 61. Transmittance σ becomes 0, and on the other hand, if the applied voltage across all PLZT plates 62 is +1/2E, the polarization axis of the light passing through the polarizing plate 6o will rotate 45 degrees clockwise across all PLZT plates 62. It becomes parallel to the polarization axis of the polarized light Fi61, and the overall transmittance σ becomes maximum. Therefore, if the initial state is that all 62/2E of the PLZT plates 62 are charged, and the applied voltage is set to +1/2E, the exposure operation will be performed, and the PLZT will be exposed at the timing corresponding to the exposure time.
When the voltage applied to all T plates 62 is set to -172E again, the exposure operation is completed. In this way, when the polarizing axis of the polarizing plate 61 is tilted +45 degrees with respect to the polarizing axis of the polarizing plate 60, the absolute value of the voltage applied to the PLZT plate 62 can be reduced to 1/2 of that of the conventional method. Although the effect can be expected, PLZ
Like all 62 elements of the T-plate 62, the circuit is equivalent to a capacitor, so in order to perform accurate exposure control, it is necessary to stabilize the initial potential regardless of the shooting interval.
It is extremely useful that the present invention is applicable to the nuclide PL Rashata. FIG. 7 is a circuit diagram showing an embodiment in which the present invention is applied to a PL rasher, and FIG. 8 is a timing chart thereof. Its structure will be explained along with its function. First, pulse TI occurs at timings corresponding to (1) power-on, (2) half-stroke of the shank button, and (3) exposure time, and pulse T2 occurs at full-stroke of the shutter button. is being done. When pulse T1 occurs when the power is turned on, this pulse T1
As a result, the transistor TRI becomes conductive, and the photothyrist 5L-84 becomes conductive, so that the left side electrode of the PLZT board 62 is charged positively and the right side electrode is charged negatively. In addition, the charging state at this time is as follows:
It is expressed as being charged to /2E. When the entire PLZT plate 62 62/2E is charged, the polarizing plate 6
Since the polarization axis of the light passing through 0 is rotated 45 degrees counterclockwise and is perpendicular to the polarization axis of the polarizing plate 61, the overall transmittance σ becomes O, and the photosensitive surface is in a light-shielded state. During the subsequent standby time, the transmittance of the PL ZT plate 62 will vary due to the discharge of all 62, and some light leakage is expected. By providing a mechanical shutter mechanism in the camera, exposure due to light leakage during standby can be prevented. Incidentally, in the case of a so-called electronic still camera, such measures against light leakage are not necessary. The amount of natural discharge during the above standby time varies depending on the shooting interval and other reasons, so at the time of each shooting, all 6 of the PLZT boards 62
2 It is required to stabilize the potential. In this embodiment, when the shutter button is pressed to perform an exposure operation, the pulse T+ generated during the half stroke makes the transistor TR1 conductive, and the PL
Since the ZT board 62 is fully charged to all 62-1/2E,
The PLZT plate 62 has a stable initial potential regardless of the amount of natural discharge during the entire 62 hours. Pulse T at the subsequent full stroke of the shutter button
2 is generated, the transistor TR2 becomes conductive due to this pulse T2, and the photothyristors S2 and S3 become conductive, so that the entire PLZT board 62 62/2E is charged. When the entire PLZT plate 62 62/2E is charged, the polarizing plate 6
Since the polarization axis of the light passing through 0 is rotated 45 degrees clockwise and becomes parallel to the polarization axis of the polarizing plate 6I, the overall transmittance σ is maximized and the photosensitive surface is exposed to the subject light. Then, when a pulse T1 is generated at a timing corresponding to the exposure time, this pulse T1 causes the transistor T
Since R+ becomes conductive again and the entire 62/2E of the PLZT plate 62 is charged, the transmittance σ of the PL rays becomes O, and the exposure operation is completed. Thereafter, the same operation as described above will be repeated every time the shutter button is pressed until the power is turned off. Further, the driving operation of the above-mentioned PL shutter is common to the driving operation of a lens shutter which opens and closes an aperture by reciprocating a set of blades using an electrostrictive element.

【effect】

As explained above, according to the present invention, in a voltage-driven shutter that performs an exposure operation by changing a controlled object member that also has a capacitance from one charged state to another charged state with a different polarity, Even if the potential of the controlled object changes due to reasons such as the length of the interval, it is possible to perform exposure after stabilizing the initial potential at the actual start of exposure, effectively eliminating exposure errors caused by fluctuations in the initial potential. It becomes possible to prevent this.

[Brief explanation of the drawing]

FIG. 1 is a mechanical diagram showing an example of a controlled mechanism when the present invention is applied to a focal plane shutter, and FIG. 2 is a circuit diagram showing an example of a circuit for controlling the voltage-driven shutter shown in FIG. 1. , Fig. 3 is a time chart of the circuit shown in Fig. 2, Fig. 4 is a perspective exploded view showing the operating principle of the PL rashata, and Figs. 5 and 6 show the relationship between applied voltage and transmittance of the PL rashata. A characteristic diagram, FIG. 7 is a circuit diagram showing an example of a circuit for applying the present invention to the PL rasher shown in FIG.
FIG. 8 is a quim chard of the embodiment shown in FIG. 11.I2.Work 3.I4...Shutter blade 51.52
...Electrostrictive element 60, 61...Polarizing plate 62-P L Z T plate Fl ・F2 ・F3...7971707121~2
Photocoupler D1-D8...Photodiode 81-Sθ...Photothyristor T1-T4...Transistor Patent applicant 37471 Co., Ltd. Attorney Patent attorney Koji Murakami Figure 7 Figure 8

Claims (3)

[Claims] (1) In a voltage-driven shutter in which an exposure operation is performed by changing a controlled object having capacitance from one charged state to another charged state with a different polarity, the first step of the exposure operation is a first means for charging the controlled object member in a direction opposite to the exposing operation; and a second means for charging the controlled object member in a direction opposite to the exposing operation.
a second means for charging the controlled object member in the direction of the original exposure operation in the step, and the first means exposes the controlled object member after an exposure time from the second step of the exposure operation. A voltage-driven shutter control circuit that charges in the opposite direction of operation. (2) The exposure operation is performed by changing a controlled object member for front curtain operation and a controlled object member for rear curtain operation having capacitance from one charged state to another charged state with a different polarity. In the voltage-driven shutter, means for charging both the controlled target members in a direction opposite to the original exposure direction in the first stage of the exposure operation, and a means for charging the controlled target member for front curtain operation in the second stage of the exposure operation. A control circuit for a voltage-driven shutter, comprising: means for charging the controlled object member for rear curtain operation in the direction of closing the aperture after an exposure period from the second stage; (3) The exposure operation is performed when the controlled object member for the first curtain operation and the controlled object member for the second curtain operation, which have capacitance, change from one charged state to another charged state with a different polarity. In the voltage-driven shutter according to the present invention, there is provided a voltage-driven shutter comprising: means for storing the charging direction of both the controlled object members having the capacitance; and a means for storing the charging direction of the both controlled object members having the capacitance; A means for charging and a second exposure operation.
A control circuit for a voltage-driven shutter, comprising: means for charging the one controlled object member in a direction opposite to the charging direction indicated by the storage means in each step;