JPH037085B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a program shutter, and more particularly to an improvement in a program shutter that makes it possible to control exposure by changing the combination of aperture diameter and shutter speed.

Conventional automatic exposure control is such that the aperture of the shutter that also serves as an aperture continuously expands and closes when a signal is output from the photometry means.Generally, the γ value of the photoelectric element in the photometry circuit is set to 0.5. When the amount of incident light from the subject changed by 1EV, the shutter speed changed by the equivalent of 0.5EV, and the aperture changed by the equivalent of 0.5EV.

When using the above method, it is necessary to control opening and closing according to the aperture amount and shutter speed according to the characteristics of the light receiving element, and the operating time error directly affects exposure accuracy, and the opening and closing continuously expands and closes.
If you set the light receiving element characteristics to reduce the size, the combination of aperture and shutter speed will be automatically determined, and you will have no choice but to use the fast speed and small aperture to the slow speed and large aperture in a linear manner. It is impossible to change the program by In addition, when shooting using a strobe, etc. as an auxiliary light, separate operations and
It becomes necessary to add another function and create and switch a specific combination of aperture and shutter speed. Further, the synchronization switch also requires information from the opening condition side, for example, means for causing a strobe light to be emitted by turning on the synchronization trigger switch when the blade opening is completed.

The object of the present invention is to easily solve these problems and provide a program shutter that is inexpensive and has excellent usability. a stepwise aperture forming means that alternately performs an expansion time period during which the aperture is expanded and a holding time period during which the aperture diameter is maintained when the expansion is stopped; a detection means for detecting the switching between the expansion time period and the hold time period of the dual-purpose shutter blade; a light receiving element; a capacitor for storing photometric information; a switching circuit that switches and controls a duty ratio so that the light-to-light output of the light-receiving element becomes approximately 1:2 in accordance with the holding time period; This is achieved by a program shutter characterized in that the exposure control is performed by driving the shutter blades that also serve as an aperture to close based on the charge in the capacitor that accumulates the output.

Hereinafter, the present invention will be explained in detail using examples and drawings.

FIG. 1 is a schematic layout diagram for explaining the mechanism of the exposure drive section of the program shutter. In the figure, the lens optical axis is perpendicular to the plane of the paper, and the lens barrel 2 is a retractable type that allows the lens to be extended and stored, so the exposure drive unit 4 and the lens barrel 2 are mechanically separated. However, the mechanism is such that the power for opening and closing the shutter is transmitted only when the lens barrel section 2 is extended.

The shutter aperture 25 of the lens barrel 2 is normally covered with shutter blades, and the shutter, which also functions as an aperture, is opened and closed by the symmetrical movement of the symmetrical shutter blades 26a and 26b. That is, the shutter blades 26a, 26b rotate around rotational shafts 261a, 261b, and are urged in a direction to close the shutter blades by springs 27a, 27b.
The shutter blades 26a, 26b have elongated holes 262a, 262b each having a cam shape for power transmission.
, the shutter blade drive member 28 provided separately
A pin 281 provided on the lever part is loosely fitted.

The shutter blade drive member 28 is biased counterclockwise around a central shaft 282, and a protrusion 283 is provided on the other lever portion. Lens barrel 2
An intermediate member 29 is provided on the outer wall portion of the intermediate member 29 so as to be in contact with the protrusion 283 and to be movable up and down. Now, when the intermediate member 29 is pushed upward from the outside of the lens barrel 2, the shutter blade drive member 28 rotates clockwise about the central shaft 282, and the pin 281 rotates to the right. As the pin 281 moves to the right, the shutter blades 26a and 26b are moved by the spring 27.
a, 27b and rotate symmetrically to open the shutter diameter portion 25. The exposure drive section 4 performs shutter exposure by pushing the intermediate member 29 with the lens barrel section 2 protruding, and is configured to control the aperture diameter and opening time by controlling the amount and duration of the push. .

The exposure drive unit 4 controls the opening time using two magnets. The combination magnet Mag1 is a magnet for opening the shutter, and the magnet Mag2 is a magnet for closing the shutter. This shows the state before exposure, that is, the shutter set completion state.

The intermediate member 29 of the lens barrel portion 2 is in a position where it is in relative contact with the plunger 41 of the exposure drive portion 4a with the lens barrel protruding. The plunger 41 is inserted into a guide 141 and is movable up and down. plunger 4
A distal end portion 421 of a lever 42 is engaged with a flange 411 provided on the lever 1 . The lever 42 is located at the axis 14
2 is a swing shaft, and a protrusion 423 is provided at the other end of the lever. There are also two levers 43 and 44 with the axis 143 as a swing axis. The lever 43 has a groove 4
13 is attached and holds the protrusion 423. Further, the lever 44 is provided with a rotating shaft 441 and a rising portion 442, a claw member 46 is placed on the rotating shaft 441, and the tip claw portion 461 of the claw member 46 engages with the rising portion 432 of the lever 43. , is biased clockwise around the rotating shaft 441, and one end of the claw member 46 is in contact with the rising portion 442. A spring 43a is attached to the lever 43, a spring 45 is attached to the lever 44,
The lever 43 is biased clockwise, the lever 44 is biased counterclockwise, and the spring 45 is biased by the springs 43a, 2.
It has the power to overcome 7a, 27b, and 28a. A protrusion 443 is provided on the lever 44 and is in contact with a step-shaped cam portion 471 of the cam plate 47.

The cam plate 47, which is movable from side to side, is urged leftward by a tensioned tension spring 144. Projections 472, 473, and 474 are fixed to the cam plate 47. The protrusion 472 is in contact with the governor 145 including the pallet and pallet gear, and the protrusion 473 is in contact with the shutter charging lever 146 during shutter charging. When the ball-shaped cam 148 rotates once counterclockwise due to the rotation of a motor (not shown), the lever 146 is moved from the shaft 14.
7 is the center of swing, and the lever 47 is pushed up to the right via the protrusion 472 to set it.

Now, when the camera release button is pressed,
Magnet Mag1 for opening the shutter receives a signal from the control system unit.
The plunger is moved to the left, the L-shaped lever 48 swings clockwise about the center shaft 149, and the engagement between the L-shaped lever 48 and the protrusion 474 of the cam plate 47 is disengaged. When the engagement is released, the tension spring 14
Since the governor 145 is operating, the cam plate 47 biased to the left by the cam plate 4 moves slowly to the left.

The lever 44 is rotated counterclockwise by the protrusion 443 that comes into contact with the cam 471 along with the moving cam plate 47, and the lever 43 engaged by the claw member 46 on the lever 44 also rotates counterclockwise. rotate in the direction. By rotating the lever 43 counterclockwise, the lever 4
2 rotates clockwise to release the tip 4 of the lever 42.
The plunger 41 engaged with the shutter 21 is pushed upward and the shutter opens. The relationship between the exposure time and the shutter opening area is determined by the cam portion 47.
1 shape, the shape of the shutter blade 26, the moving speed of the cam plate 47, etc. A switch SSW or other detection member is provided near the cam plate 47, and is structured to emit a signal corresponding to the aperture diameter of the shutter.

Next, when the shutter opening signal is issued from the AE control section IC of the control system unit, the magnet opens.
2 is activated and the plunger is pushed upward. The L-shaped lever 49, which is biased clockwise with the center shaft 150 as its pivot center, rotates clockwise with the movement of the plunger, and the rising end portion 491 of the L-shaped lever 49 moves the claw member 46 counterclockwise. kick it away. As a result, the tip claw portion 461 of the claw member 46 disengages from the rising portion 432 of the lever 43, the lever 43 is rotated clockwise by the spring 45, and the lever 42 is rotated counterclockwise via the protrusion 423. The plunger 41 is rotated in this direction to push down the plunger 41 and close the shutter.

When the shutter is opened and closed, the motor M rotates according to the sequence, the lever 146 reciprocates around the shaft 147 and pushes the cam plate 47 to the right, and the L-shaped lever 48 engages with the protrusion 474. Returns to the state shown. Lever members 42, 43, 4
4 and the claw member 41 are also returned to the shutter charging state before opening by a return member (not shown) in conjunction with the operation of the lever 146 described above.

Next, the program automatic exposure control of the present invention, which is exposed by the above-mentioned exposure drive section 4, will be explained.
FIG. 2 is an aperture-shutter time graph.
The aperture and shutter blades that started opening at time _t0 are
At time _t1 , the aperture diameter becomes equivalent to F8, for example, following the line AB. Then, until time _t2, the aperture diameter is maintained at line BC, which is F8, and after time _t2 , the aperture diameter is changed to line CD, where the aperture diameter is equivalent to, for example, F4.
Here, the DE line again maintains the aperture diameter of F4.
The diaphragm/shutter blade operates as described above and exposes the film surface.
Information from a photoelectric element such as CbS causes the shutter blade to close while the shutter blade is opening.

FIG. 3a shows a photometry circuit adapted to the shutter blade operation of FIG. 2. The light receiving element PC uses two light receiving elements PC, R ₁ , PC, R ₂ with different γ values, γ=1.0 and γ=0.5, as shown in FIG. 3b. Photodetector PC,
Switching of R ₁ , PC, and R ₂ is performed by the detection unit SSW1 of the exposure drive unit 4 shown in FIG. -2,4
75-3. First, at time t ₀ when the shutter starts opening, the switch on the photodetector PC and R ₂ side is activated.
PSW2 turns ON, and then at time _t1 , the light receiving element PC,
Switch PSW1 on _R1 side turns on and switch PSW
2 is turned off. Furthermore, at time t ₂ , switch PSW1
is turned OFF, and the switch on the photodetector PC, R ₂ side is turned off.
PSW2 turns ON. At time t ₃ , the photodetector PC,
Switch PSW1 on _R1 side turns on and switch PSW
2 is turned off. While such switching is being performed, the capacitor C for storing photometric information is charged. One terminal of the comparator COMP receives a reference voltage divided and set according to the film's ASA sensitivity, etc., and the other terminal receives the charging voltage for the capacitor C, and the time t ₄ when both become equal is input.
A command to close the shutter is issued and the shutter closes.

The program automatic exposure control method explained above is
(1) Take camera shake into consideration and use a device with a wide interlocking range as much as possible. (2) When using the conventional automatic exposure control method to fire a strobe, the flash fires at the moment the shutter begins to close. Therefore, in the case of electrical control, the disadvantage that it is difficult to capture this moment is overcome, and the light emission time can be set relatively easily, making it suitable for cameras with built-in strobes. It has a new feature.

FIG. 4 shows a photometry circuit which has been further improved in response to the shutter blade operation shown in FIG. In contrast to the photometric circuit shown in FIG. 3, which uses two light receiving elements with different γ values, γ=0.5
Using one photodetector element PC, _R2 , and using this as the circuit shown in Fig. 4a, a switching circuit PSS for charging the capacitor C for storing photometric information,
Perform switching as shown in Fig. 4b, and set the time.
There are fine pulses between t ₁ and t ₂ and between times t ₃ and t ₄ .
By performing alternating ON/OFF switching, it has the same photoelectric effect as the photodetector PC, _R1 with γ=1.0 explained in FIG.

The embodiment of the present invention described above has the following features: (1) In an exposure control system in which one set of blades serves as both an aperture and a shutter, the aperture aperture adjustment member includes a cam portion that determines the aperture aperture amount, and an electric This program shutter is provided with a part that generates electrical information, and the exposure amount is controlled by linking the aperture condition of the diaphragm aperture adjusting member and the characteristics of the light receiving element using the electrical information.

(2) The cam part of the aperture aperture adjusting member is divided into a part where the aperture continuously expands in conjunction with the operation of the aperture aperture adjusting member and a part where the aperture stops in response to the operation of the aperture aperture adjusting member. This is a program shutter that has been designed to have.

(3) The generation of electrical information linked to the aperture is controlled by a switch linked to the operation of the diaphragm aperture adjustment member.
This is a program shutter that controls the light receiving element characteristics and aperture conditions by turning on and off.

In this way, it was possible to obtain a program shutter that was inexpensive and had excellent usability.

[Brief explanation of the drawing]

FIG. 1 shows a schematic layout of an exposure drive section of the present invention. FIG. 2 shows an aperture shutter time graph. FIG. 3a shows a photometric circuit, and FIG. 3b shows a light-receiving element characteristic curve used therein. FIG. 4a shows another photometric circuit, and FIG. 4b shows the switching state used therein. 2... Lens barrel section, 4... Exposure drive section, 25... Shutter diameter section, 26... Shutter blade, 47... Cam plate, 145... Governor, Mag... Magnet,
SSW...Switch, PC...Photodetector.

Claims (1)

[Scope of Claims] 1. A shutter blade that also serves as an aperture, and a stepwise method in which an expansion time period in which the shutter blade also serves as an aperture is expanded and a holding time period in which the aperture diameter is maintained when the expansion is stopped are alternately performed multiple times. an aperture forming means; a detecting means for detecting a switch between an opening time period and a holding time period of the shutter blade that also serves as an aperture through movement of the stepwise aperture forming means; a light receiving element; and a photometric information storage device. Based on the output signal from the capacitor and the detection means, the duty ratio is switched and controlled so that the light output of the light receiving element becomes approximately 1:2, corresponding to the expansion time period and the holding time period. and a switching circuit to control the exposure by driving the shutter blades that also serve as an aperture to close based on the charge charged in the capacitor that accumulates the output of the light receiving element controlled by the switching circuit. A program shutter featuring the following.