JPH0652361B2 - Camera shutter control device - Google Patents

Description

The present invention relates to a shutter control device for a camera.

[Description of the Prior Art] In a shutter control device for a camera, a shutter is controlled so as to follow a predetermined aperture characteristic through coincidence control between a detected shutter opening and a control signal that gives a target aperture characteristic. A drive control is known. In this case, to detect the shutter opening, a diaphragm hole whose size changes according to the opening operation of the shutter is provided, and the light emitting element and the light receiving element are fixedly placed across the diaphragm hole to close the shutter. When the shutter is closed, the aperture should be closed so that the light emitted from the light emitting element to the light receiving element is blocked, and the aperture is opened as the opening of the shutter increases so that the amount of light received by the light receiving element increases. Is being carried out by

When the shutter opening is detected, if the diaphragm hole is closed when the shutter is closed as described above and the light emission of the light emitting element is blocked and is not given to the light receiving element, light is emitted before the opening operation of the shutter. It is impossible to know through the light receiving element whether or not the element gives a predetermined light emission amount.
The amount of light emitted from the light emitting element easily fluctuates due to, for example, fluctuations in the power source, and if the amount of light emitted fluctuates, the amount of light received will differ even if the aperture of the aperture is the same, and this will interfere with detection of the shutter opening. Therefore, if the light emission amount can be known through the light receiving element before the opening operation of the shutter, the light emitting element can be controlled so that the predetermined light emission amount can be obtained, and the adverse effect caused by the variation of the light emission amount can be prevented. It will be convenient for you.

[Object of the Invention] The present invention has been made based on the above viewpoint, and an object thereof is to control the light emission amount of the light emitting element to be constant through the light receiving element before the opening operation of the shutter. Another object of the present invention is to provide a shutter control device for a camera, which is effective in preventing the adverse effect caused by the fluctuation of

[Means for Achieving the Object] In the present invention, in a device for controlling opening and closing of a shutter of a camera, a diaphragm mechanism for monitoring the opening of the shutter, a light emitting element and a light receiving element optically related to the diaphragm mechanism. And a shutter opening detection means configured to have a maximum light receiving amount of the light receiving element by the light projecting of the light emitting element when the shutter is closed and to decrease in accordance with an increase in the opening of the shutter. A light emission control means for controlling the light emission amount of the light emitting element to be constant based on the photoelectric output of the light receiving element when the shutter is closed; and a reference signal for giving a photoelectric output of the light receiving element and a shutter opening characteristic. And a shutter drive control means for controlling the opening and closing of the shutter so as to comply with the aperture characteristic based on To achieve.

[Embodiment of the Invention] FIG. 1 is a block diagram showing an embodiment of the present invention.

In the drawing, shutter blades 1, 2 and 3 are used to open and close the lens opening 4 by these three blades. The lens opening 4 is formed on a substrate (not shown), and the shutter blades 1, 2 and 3 are arranged inside the camera via this substrate. Each of the shutter blades 1, 2, 3 has arm portions 1a, 2a, 3a, respectively, and the end portions of the arm portions 1a, 2a, 3a and the support shafts 5, 6, 7 fixed to the substrate are provided. It is rotatably supported by the engagement between the two. A shutter drive plate 8 is provided between the shutter blades 1, 2, 3 and the substrate. Shutter drive plate 8
Is a thin disk-shaped, has a circular opening in the center, and this circular opening engages with a peripheral wall (not shown) projecting around the lens opening 4 of the substrate, so that the lens opening 4 can be easily centered. It is designed to rotate. The shutter drive plate 8 is provided with pins 9, 10, 11 protruding from the shutter blades 1, 2, 3, respectively. Each pin 9, 10, 11 is an elongated hole 1 formed in the arm portions 1a, 2a, 3a of the shutter blades 1, 2, 3.
The shutter blades 1, 2 and 3 are opened and closed by engaging the shutter blades 2, 13 and 14 and rotating the shutter drive plate 8. The shutter drive plate 8 is integrally formed with a drive shaft 15 extending in the outer radial direction and an opening detection plate 16.
The drive shaft 15 is substantially L-shaped, and a groove portion 19 that engages with the pin 18 of the pin member 17 is formed at the lower end of the drive shaft 15. The pin member 17 is connected to a movable piece 21 of a linear solenoid 20 fixed to a substrate (not shown), and can be operated in a direction indicated by an arrow by rotating the movable piece 21 about a support shaft 22. There is. In this example, the shutter blades 1, 2 and 3 are closed by moving the pin member 17 in the a direction, and the shutter blades 1, 2, and 3 are closed by moving the pin member 17 in the b direction.
3 is configured to open.

FIG. 2 is a configuration diagram of the linear solenoid 20. The movable piece 21 is held by the outer frame 25 and the inner frames 26 and 27 together with the electromagnetic winding 23 and the permanent magnet 24. The outer frame 25 and the inner frames 26, 27 are made of a material having a high magnetic permeability such as soft iron. The outer frame 25 is a U-shaped frame body having three substantially rectangular surfaces 25-1, 25-2, 25-3, and one inner frame 26 is provided inside the surface 25-1. 25-1 inside the surface 25-3 facing the permanent magnet 2
The other inner frame 27 is provided via 4. Inner frame 26
And 27 are each made of a rectangular plate material, and have an outer frame 25
End portions projecting from are separated and bent so as to face each other, and tip portions 26a and 27a thereof are convexly formed in an arc shape. The permanent magnet 24 sandwiched between the surface 25-3 of the outer frame 25 and the inner frame 27 is a rectangular plate magnet, and in this example, the surface in contact with the inner frame 27 is provided so as to have the N pole. . The electromagnetic winding 23 is provided between the inner frames 26 and 27 via a plastic winding frame 28. Reel 2
8 has a through space 29 for receiving the movable piece 21 in the central portion, and flange portions 28a, 28b are formed on both end surfaces. The reel 28 has its flange portions 28a, 28b.
It is fixed to the outer frame 25 via. The movable piece 21 is a substantially elongated plate member made of a material having a high magnetic permeability, and is arranged through the penetrating portion 29 of the winding frame 28. One end 21a of the movable piece 21 has a tip portion 26a of the inner frames 26, 27.
And 27a, and the other end 21b is pivotally supported by a support shaft 22 so as to be rotatable in the left-right direction in the drawing. The pin member 17 described with reference to FIG. 1 is attached to the protruding end 21 a of the movable piece 21. The movable piece 21 has a distal end portion 26a of the inner frames 26, 27 near the one end 21a.
The projecting portions 30a and 30b are provided so as to be orthogonal to the axial direction along the inner surface of 27a. Inner frame 26, 2
The overhanging portion 3 that faces the inner surfaces of the tip portions 26a and 27a of
The sides of 0a and 30b are formed in an arc shape like the inner surfaces of the tip portions 26a and 27a so that the distance from the inner surfaces of the tip portions 26a and 27a is always substantially constant regardless of the rotation of the movable piece 21. Has been done.

When the electromagnetic winding 23 is in the non-excited state, the movable piece 21 is given a magnetic flux passing through the permanent magnet 24 → the inner frame 27 → the tip portion 27a → the movable piece 21 → the outer frame 25 → the permanent magnet 24. It is sucked and its one end 21a is an inner frame 27.
2 is held in a state of being tilted to the right as shown in FIG. In this state, as shown in FIG. 1, the pin member 17 is operated to the a side, and the shutter blades 1, 2 and 3 are held in the closed state. On the other hand, when the electromagnetic winding 23 is excited so as to cancel the magnetic flux of the permanent magnet 24, the surface 25-1 of the outer frame 25 and the inner frame 26 → the surface 25-2 of the outer frame 25 → the movable piece 21. The other end 21b of
→ One end 21a of the movable piece 21 → Tip portion 26a of the inner frame 26
→ The first magnetic flux passing through the surface 25-1 of the outer frame 25 and the inner frame 26, and the surface 25-3 of the outer frame 25 and the inner frame 27 → the outer frame 25
Surface 25-2 → the other end 21b of the movable piece 21 → one end 21a of the movable piece 21 → the tip portion 27a of the inner frame 27 → the second magnetic flux passing through the surface 25-3 of the outer frame 25 and the inner frame 27. To do. The second magnetic flux acts so as to cancel the magnetic flux of the permanent magnet 24, and the attractive force of the first magnetic flux acts on the movable piece 21, so that the movable piece 21 rotates toward the tip portion 26a of the inner frame 26. It will be.

The linear solenoid 20 having such a configuration has a movable piece 21.
Regardless of the rotational position of the, a substantially constant torque is generated according to the exciting current. That is, when an exciting current of a certain value is applied to the electromagnetic winding 23, the torque acting on the movable piece 21 becomes substantially the same at any position between the tip portions 26a and 27a of the inner frames 26, 27. . Then, if the magnitude of the exciting current is changed, the torque changes, and the rotating speed of the movable piece 21 at the time of exciting the electromagnetic winding 23 changes accordingly.

Returning to FIG. 1, the opening detection plate 1 integrated with the shutter drive plate 8.
6, a diaphragm hole 31 is formed, and a light emitting element 32 and a light receiving element 33 are fixedly arranged with the diaphragm hole 31 interposed therebetween, and the light projecting from the light emitting element 32 through the diaphragm hole 31 reaches the light receiving element 33. To be given. The aperture hole 31 has a maximum opening with respect to the light emitting element 32 and the light receiving element 33 which are fixedly arranged, when the shutter blades 1, 2 and 3 are fully closed, and opens in accordance with an increase in the opening degree of the shutter blades 1, 2, and 3. Of the shutter blades 1, 2 and 3 is reduced to a minimum opening when fully opened. Therefore, the amount of light received by the light receiving element 33 is maximum when the shutter blades 1, 2, 3 are fully closed, and decreases as the opening of the shutter blades 1, 2, 3 increases, and the shutter blades 1, 2, 3 are fully opened. Sometimes the minimum. As the light emitting element 32 and the light receiving element 33, a light emitting diode, a photodiode or the like can be used.

Reference numeral 34 is a control circuit. The control circuit 34 controls the light emitting element 32.
The photoelectric output of the light receiving element 33 due to the light projection is input, and the light emission amount of the light emitting element 32 is controlled to be constant based on the photoelectric output of the light receiving element 33 when the shutter blades 1, 2 and 3 are fully closed. The linear solenoid 20 is controlled based on the photoelectric output of the light receiving element 33 and the reference signal giving a predetermined shutter opening characteristic so that the opening operation of the shutter blades 1, 2 and 3 follows the opening characteristic.

FIG. 3 is a block diagram of the control circuit 34. _A light receiving circuit 340 outputs the photoelectric output of the light receiving element 33 as a voltage signal V _A , and has an amplifier 340a and a resistor 340b.
The voltage V _R2 applied to the (+) input terminal of the amplifier 340a is a reference voltage for pulling up. When the resistance value of the resistor 340b is R and the photocurrent of the light receiving element 33 is I, the voltage signal V _A output from the light receiving circuit 340 is V _A =
It becomes _VR2 + _IR .

_A control amplifier 341 inputs the voltage signal V _A and the reference voltage V _R1 and outputs a control voltage V _B for controlling the drive current of the light emitting element 32 so that the voltage signal V _A becomes the reference voltage V _R1 . Reference numeral 342 is an open / close switch for turning on / off the supply of the control voltage V _B , which is opened by an open signal given in synchronization with shutter release and closed by a close signal given in synchronization with the end of exposure. 343 is an open / close switch 34
A hold circuit for holding the control voltage V _B given via the line 2, which has a capacitor 343a and an amplifier 343b. The amplifier 343b constitutes a voltage follower, and when the open / close switch 342 is off, the capacitor 34
The control voltage V _B charged in 3a is applied to the base of the control transistor 344 through the voltage follower. The collector of the control transistor 344 is connected to the power supply via the light emitting element 32, and the emitter thereof is grounded.

Reference numeral 345 denotes an operational circuit having an operational amplifier 345a. The voltage signal V _A is applied to the (+) input terminal of the amplifier 345a via the resistor R ₁ and the voltage V _C is applied via the resistor R _2. ) A reference signal V _R3 which gives a predetermined shutter opening characteristic is applied to the input terminal via a resistor R ₃ . The voltage V _C is a bias voltage for canceling the magnetic flux of the permanent magnet 24 of the linear solenoid 20 so that no force acts on the movable piece 21. The reference signal V _R3 is given in synchronism with the shutter release and has a characteristic as shown in FIG. 4, for example, and the shutter blades 1, 2, 3 are in the inclined portion from the shutter release to time t _1.
The opening operation time of the shutter blades 1, 2 and 3 is restricted by the inclined portion from the time t ₂ to the end of the exposure. Arithmetic circuit 345, its output if the resistance value is equal give _{(V A + V C -V R3} ) becomes, V _A is equal to V _R3 Such operation output V _D. A linear solenoid drive circuit 346 drives the electromagnetic winding 23 according to the operation output V _D of the operation circuit 345.

With the above-mentioned configuration, when the power supply is not applied to the control circuit 34, since the movable piece 21 of the linear solenoid 20 is attracted by the permanent magnet 24, the shutter blades 1, 2 and 3 are fully closed and the diaphragm is closed. The hole 31 is fully opened with respect to the light emitting element 32 and the light receiving element 33. When power is applied to the control circuit 34 prior to the shutter release, the light emitting element 32 is controlled by the control voltage V _B of the control amplifier 341 which controls the drive current of the light emitting element 32 so that the voltage signal V _A becomes the reference voltage V _R1. Is driven, and the light-emitting element 3
The light emission amount of No. 2 is controlled to be constant. When the shutter release is performed, the open / close switch 34 is synchronized with this.
2 is opened, and the control voltage V _B is held in the hold circuit 343. Since the transistor 344 controls the drive current of the light emitting element 32 with a constant current based on the held control voltage V _B , the light emission amount of the light emitting element 32 is kept constant.

When the shutter release is performed, the reference signal V _R3 that gives the shutter opening characteristic is applied to the arithmetic circuit 345, and the arithmetic output V _D that equalizes the voltage signal V _A given through the light receiving circuit 340 to the reference signal V _R3. Are provided to the linear solenoid drive circuit 346. As a result, the electromagnetic winding 23 of the linear solenoid 20 is excited, the movable piece 21 rotates toward the side opposite to the side of the permanent magnet 24, and the shutter blades 1, 2, and 3 of the shutter blades 1 and 2 are moved through the shutter drive plate 8. The opening operation is performed. The openings of the shutter blades 1, 2 and 3 are reflected in the voltage signal V _A due to the decrease in the amount of light received by the light receiving element 33 as the aperture of the diaphragm hole 31 is decreased by the rotation of the shutter drive plate 8.
Then, the excitation control of the electromagnetic winding 23 is performed through the arithmetic circuit 345 and the linear solenoid drive circuit 346 so that this voltage signal always matches the reference signal V _R3 .
Similarly, when the shutter blades 1, 2, 3 are closed, the movable piece 21 is rotated toward the permanent magnet 24 according to the operation output V _D that makes the voltage signal V _A equal to the reference signal V _R3. The closing operation of the shutter blades 1, 2 and 3 is performed.

In the embodiment described above, the aperture of the shutter blade is detected by the aperture hole 31, but an optical filter is provided instead of the aperture hole so that the amount of light received through this optical filter is the same as that in the above-described embodiment. You may comprise.

[Effects of the Invention] As described above, according to the present invention, a light emitting element and a light receiving element optically associated with the diaphragm mechanism for monitoring the opening of the shutter are provided, and the light receiving amount of the light receiving element is maximized when the shutter is closed. Since it is configured to decrease as the shutter opening increases, the light emitting element is controlled so that the light emitting amount becomes constant based on the light receiving amount when the shutter is closed.
It is possible to provide a camera shutter control device capable of preventing fluctuations in the amount of light emission due to fluctuations in the power supply and accurately detecting the opening of the shutter regardless of fluctuations in the power supply.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG.
The block diagram which shows an example of the linear solenoid in a figure, 3rd
FIG. 4 is a block diagram showing an example of the control circuit in FIG.
The figure is an illustration of a reference signal that gives the shutter opening characteristic. 1, 2, 3 ... Shutter blade, 8 ... Shutter drive plate,
16: opening detection plate, 17: pin member, 20: linear solenoid, 21: movable piece, 23: electromagnetic winding, 2
4 ... Permanent magnet, 31 ... Aperture hole, 32 ... Light emitting element,
33 ... Light receiving element, 34 ... Control circuit, 340 ... Light receiving circuit, 341 ... Control amplifier, 342 ... Open / close switch, 343 ... Hold circuit, 344 ... Control transistor, 345 ... Arithmetic circuit, 346 ... … Linear solenoid drive circuit

Claims (1)

[Claims] 1. An apparatus for controlling opening / closing of a shutter of a camera, comprising: a diaphragm mechanism for monitoring the opening of the shutter; and a light emitting element and a light receiving element optically associated with the diaphragm mechanism, wherein the light emitting element. The light receiving amount of the light receiving element due to the projection of is maximum when the shutter is closed, and is decreased in accordance with an increase in the opening of the shutter, and the shutter opening detection means when the shutter is closed. Based on the photoelectric output of the light receiving element, the light emission control means for controlling the light emitting amount of the light emitting element to be constant, and the photoelectric output of the light receiving element and the reference signal for giving the shutter opening characteristic to comply with the aperture characteristic. And a shutter drive control means for controlling the opening and closing of the shutter.