JP2538314Y2 - Exposure device for program shutter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an exposure apparatus for a program shutter capable of selecting a program mode and an aperture priority mode.

[Conventional technology]

A shutter blade opening / closing device for opening and closing the shutter blade at a predetermined shutter speed (effective exposure time) and a diaphragm device for setting the diaphragm blade to a predetermined aperture value are provided separately in a programmed shutter of a camera. In some cases, either the program mode or the aperture priority mode can be selected and controlled. As shown in the table of FIG. 4, it is assumed that the maximum shutter speed at the maximum aperture (aperture value: F4) of this shutter is 1/250 second, and that the shutter can be controlled at the minimum aperture (F16). If the maximum shutter speed is 1/1000 second, the maximum exposure value that can control proper exposure is EV18.

Therefore, when the program mode is selected in this shutter, the EV is set according to the photometry result of the subject.
For 18 the combination of 1/1000 second and F16, for EV17 1
Combination of / 500 sec and F16, 1/500 sec and F11 for EV16
By reading the unique combination information of the predetermined shutter speed and the aperture diameter from the program ROM as in the case of the combination, the aperture blade and the shutter blade are controlled. However, according to this example, in the case of EV16, the combination of 1/500 second and F11 is decided, so it is necessary to switch to the closing action from the middle without opening the shutter blade to the maximum aperture (F4). The operation waveform of the shutter blade becomes a triangular wave.
Then, since the operation waveform is also the exposure aperture waveform, the diaphragm blade is not particularly operated to the position of F11.

On the other hand, when the aperture priority mode is selected, as apparent from the table of FIG.
F8, F11, and F16 can be selected, and the shutter speed corresponding to each of them can be automatically determined. Therefore, the exposed aperture waveform in this case is a trapezoidal (trapezoidal) wave in principle.

[Problems to be solved by the invention]

By the way, a recent camera shutter uses an electromagnetic actuator such as a moving magnet type motor (iris motor) as a drive source of the shutter. According to the demand for power reduction,
There is a limit to how fast the shutter blades can be operated due to low power. Therefore, as shown in FIG. 4, when the maximum shutter speed obtained by such an electromagnetic actuator is 1/250 second at the time of full opening (F4), when the aperture priority mode is selected, the exposure of EV17 or more is performed. You cannot shoot with the value.

In the table of FIG. 4, when the exposure values are EV13, EV14, EV15, and EV16 in the aperture priority mode, the aperture values are set to F5.6, F8, F11, and F16, respectively. It is thought that a shutter speed of 1/250 second can be obtained properly, but in practice, an appropriate 1/250 second cannot be obtained, and only when F4 is set at EV12, You can only get 1/250 second. That is, needless to say, the fact that the maximum speed of this shutter is 1/250 sec.
As shown in the aperture waveform diagram schematically shown in the figure, the time at a height position that is half the height of the triangle is 1/250 seconds. Therefore, when the aperture value of the EV13 is set to F5.6, the shutter blades are also operated to the full open (F4) and then closed in this case, so that in practice, the time T 'is longer than 1/250 second. Become. Similarly, the same applies when the aperture is reduced to F8 or more.

In order to solve these problems, if the shutter blade is opened to a preset aperture value position, that is, to the aperture position formed by the aperture blade, and then it is possible to close from that position, the shutter blade starts to open. The time from closing to the end of closing can be reduced, and an appropriate shutter speed can be obtained. Also, in that case, if you close it earlier than the time when 1/250 seconds can be properly obtained, EV
It is not impossible to shoot with the exposure value of 17 or EV18. However, in order to stop the shutter blade at the position of the preset aperture value in such a manner, the aperture regulating member is moved forward and backward according to the preset aperture value, and the shutter blade or its operating member is applied thereto. However, in such a case, the shutter blades bounce and the trapezoidal opening waveform is broken, so that a problem occurs in which an appropriate exposure value cannot be obtained. In addition, the effect is remarkable when a small aperture value is set when the exposure value is large.

The present invention has been made in view of such a problem, and in a program shutter in which a program mode and an aperture priority mode can be selected, when an aperture priority mode is selected and a desired aperture value is set, a shutter blade is formed by the aperture blade. Stopped at an opening position slightly larger than the opening, and after a predetermined time, closed from that position, so that an appropriate shutter speed can be obtained over a wide range of exposure values for a set aperture value. It is an object of the present invention to provide a light exposure apparatus.

[Means for solving the problem]

The exposure apparatus for a program shutter according to the present invention includes a shutter blade and an aperture blade, and sets an appropriate aperture value when the aperture priority mode is selected in a program shutter capable of selecting the program mode and the aperture priority mode. Aperture setting means, an aperture regulating member for stopping the opening operation of the shutter blade at an opening position slightly larger than the opening formed by the aperture blade according to the aperture value when the aperture value is set, and the aperture value When set, an electric second setting means for setting a control time for obtaining a shutter speed corresponding to the aperture value and the exposure value in consideration of the opening operation stop position of the shutter blade, and a shutter according to the control time Control means for outputting a blade opening / closing operation signal to the shutter blade opening / closing means.

[Action]

When the aperture priority mode is selected and an appropriate aperture value is set by the aperture setting means, the aperture blade is operated to the aperture forming position corresponding to the aperture value, and the aperture regulating member is used to open the aperture blade. It is operated to a position where the operation is stopped at a position slightly larger than the aperture diameter. On the other hand, when the exposure value is determined by measuring the subject, the shutter speed is determined by the aperture value and the exposure value. However, the electric second setting unit requires that the shutter blade stop at the aperture position slightly larger than the aperture diameter. In consideration of the above, the control time required to obtain the shutter speed is set. The control means operates the shutter blade opening / closing means based on the set control time to open / close the shutter blade. Therefore, even if the shutter blades abut on the opening regulating member in the opening operation and bounce, the exposure aperture waveform is not affected, and an appropriate exposure value can be obtained, even in the aperture priority mode. .

〔Example〕

Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram of a main part of an exposure apparatus in a camera program shutter. In the figure, reference numeral 1 denotes an aperture value setting means which can select and set an appropriate aperture value in advance. Accordingly, the aperture blade and the aperture regulating member (not shown) are moved to predetermined positions manually or by an electromagnetic actuator. The opening regulating member is a member that regulates the opening operation amount of the shutter blade, and specific examples of such a member include:
For example, it is described in the specification of Japanese Utility Model Application No. 2-92550 (Japanese Utility Model Application Laid-Open No. 4-50829) proposed by the present applicant. Reference numeral 2 denotes a photometry circuit for photometry of an object to obtain photometry data, 3 denotes an A / D converter for converting the obtained photometry data into a digital quantity and inputs the same to the CPU 4, and 5 denotes an aperture priority mode. The aperture priority R0M is provided with a TV table for reading the shutter speed based on the exposure value and the aperture value in the case. The program table for reading the aperture value and the shutter speed based on the exposure value when the program mode is selected. It is a program ROM provided.

In the CPU 4, 8 sets the control time necessary to obtain the shutter speed obtained from the TV table in consideration of the fact that the shutter blade stops at the aperture position slightly larger than the aperture diameter in the opening operation. Second time setting means, storage means 9 for temporarily storing the set shutter speed, and control means 10 for outputting the stored shutter speed signal as a control signal for the shutter blades.

Reference numeral 11 denotes a drive circuit for driving an actuator 12 for driving shutter blades based on a control signal.

This embodiment is configured as described above, and the operation will be described next with reference to the flowchart of FIG.

For example, it is assumed that the aperture priority mode is selected by a selection unit (not shown) in a program shutter capable of achieving a shutter speed of 1/250 second when the shutter is fully opened (at this time, the aperture value is F4, for example).

When the shutter is released, first, an aperture regulating member and aperture blades (not shown) are actuated to predetermined positions by an electromagnetic actuator in accordance with the set appropriate aperture value A. Of course, such an operation may be performed when the aperture value A is set. In such a predetermined position, the aperture regulating member can stop the opening operation of the shutter blade at the aperture position slightly larger than the aperture diameter. On the other hand, the aperture value A is read as AV (= log ₂ A ² ) into the TV table of the aperture priority ROM 5 via the CPU 4 and the shutter speed group TV (= log ₂ 1 / T) corresponding to the set aperture value AV , Where T: shutter speed) is selected. Exposure value EV = TV
It is represented as + AV.

Next, when the film sensitivity is read and the subject is measured by the photometric circuit 2, the photometric data is input to the CPU 4 as photometric data, and the exposure value EV is calculated. Then, an optimal shutter speed TV is determined from the shutter speed group selected based on the exposure value EV and the aperture value AV in the TV table of the aperture priority ROM 5 and read. Further, the TV value is adjusted by the electric second setting unit 8 in consideration of the fact that the opening operation is stopped by the aperture regulating member at the aperture position slightly larger than the aperture position corresponding to the aperture value A in the shutter blade. The electric time T at which a proper shutter speed is obtained is set and temporarily stored in the storage means 9. Then, a control signal for controlling the opening operation time of the shutter blade according to the electric time T is output from the control means 10 to the drive circuit 11, and
12 is driven. Then, the shutter blades (not shown) perform an opening operation to an opening position regulated by the opening regulating member, and when the output of the control signal is interrupted after a predetermined time, the shutter blade is closed from the position by a well-known means such as an elastic member. And the exposure ends.

Thus, when exposure is performed in the aperture priority mode, the aperture waveform becomes a trapezoidal wave. However, since the shutter blades stop opening at a position slightly larger than the aperture opening, even when the shutter blades abut against the aperture regulating member and do not enter the aperture opening, the shutter aperture does not affect the predetermined aperture waveform. Nothing to give. Therefore, an appropriate exposure value can be obtained.

Further, as described above, the opening operation of the shutter blade is stopped at the position of the diameter slightly larger than the aperture opening, and after a predetermined time, the closing operation is performed from the position. By shortening, the controllable range when shooting in the aperture priority mode is widened by the aperture priority mode. That is, as described above, the maximum shutter speed when fully opened is
If the aperture value is set to F5.6 when the shutter speed is 1/250 second, the shutter speed of 1/250 second cannot be obtained accurately with the EV13 as long as the shutter blades are operated to the fully open (F4) state. , Actually it will be slower than 1/250 second,
According to the present embodiment, in FIG.
Since it stops at a position slightly open from the position of F5.6, even if you close it sufficiently and perform the closing operation,
1/250 second will be obtained accurately.

Further, according to the table shown in FIG. 4, when shooting under the condition of EV13, if F4 is set, an appropriate exposure value cannot be obtained. Similarly, when shooting under EV16 conditions, F1
It has to be set to 6, and in that case, the shutter speed is not an appropriate 1/250 second as described above. Furthermore, under the condition of EV17 or more, it can be said that photographing is practically impossible. However, according to the present embodiment, it is possible to obtain shutter speeds of 1/500 sec. And 1/1000 sec., Even if the maximum shutter speed of the fully opener (4) is 1/250 sec. FIG. 3 is a diagram for explaining this.

In the third diagram shows the stop position of the opening operation of the shutter blade in the case of setting the F5.6 in a _1, F8
It is indicated by a ₂ a stop position of the opening operation in case of setting the. In the case of the aperture priority mode, the opening waveform becomes a trapezoidal wave, but as can be seen from this figure, in this embodiment, when the start time of the closing operation is made as fast as possible, the operation waveform of the shutter blade becomes a triangular wave. And the exposed aperture waveform becomes a trapezoidal wave close to a triangular wave. This drawing shows that when so operated, 1/500 second is obtained for F5.6 and F8
Indicates that 1/1000 second can be obtained. Therefore, as can be seen from FIG. 4, in this case, no restrictions are imposed on the EV13, and F8, F11, and F16 can be set on the EV16.
Even in the case of V18, shooting is possible, albeit conditional, as in the case of EV16.

When the program mode is selected, an aperture value and a shutter speed are set based on photometric data in the same manner as in the related art.

[Effect of the invention]

As described above, the exposure device of the program shutter according to the present invention includes an aperture setting unit that sets an aperture value when the aperture priority mode is selected, and an aperture that is slightly smaller than an aperture formed by aperture blades according to the aperture value. An opening regulating member for stopping the opening operation of the shutter blade at a large opening position, and an electric second for setting a control time for obtaining a shutter speed corresponding to the aperture value and the exposure value in consideration of the opening operation stop position of the shutter blade. Since the time setting means and the control means for outputting the shutter blade opening / closing operation signal to the shutter blade opening / closing means in accordance with the control time are provided, the controllable range of the exposure value at the time of selecting the aperture priority mode is widened, Moreover, an appropriate shutter speed can be obtained even if the aperture value is different. Further, even if the shutter blades bounce, an appropriate exposure value can be secured.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part showing an embodiment of an exposure apparatus according to the present invention, FIG. 2 is a flowchart of the apparatus of FIG. 1, and FIG. FIG. 4 is a table showing a relationship between an exposure value, an aperture value and a shutter speed, and FIG. 5 is a view similar to FIG. 1 ... Aperture value setting means, 8 ... Electric second time setting means, 10 ...
... Control means, 12 ... Actuators.

Claims (1)

(57) [Scope of request for utility model registration] An aperture setting means for setting a proper aperture value when an aperture priority mode is selected in a program shutter having a shutter blade and an aperture blade and capable of selecting a program mode and an aperture priority mode; ,
An aperture regulating member for stopping the opening operation of the shutter blade at an opening position slightly larger than the aperture formed by the aperture blade according to the aperture value when the aperture value is set; and a shutter when the aperture value is set. An electric second setting unit for setting a control time for obtaining a shutter speed corresponding to the aperture value and the exposure value in consideration of the opening operation stop position of the blade, and an opening / closing operation signal for the shutter blade according to the control time. An exposure device for a program shutter, comprising: a control unit for outputting to a shutter blade opening / closing unit.