JPH075469Y2 - Aperture priority AE shutter aperture aperture control device - Google Patents

Description

[Detailed Description of the Invention] <Industrial field of application> The present invention is a diaphragm for a diaphragm-priority AE shutter that uses a motor-driven diaphragm shutter blade to obtain a preset diaphragm aperture. The present invention relates to a caliber control device.

<Prior Art> In order to obtain a preset aperture diameter of this type, a mechanical limiting member is inserted, and the aperture blade (shutter blade) is locked and fixed at the position of the limiting member. It was done and there was nothing to control it electrically.

<Problems to be solved by the invention> However, in order to fix the shutter blades with such a limiting member, the mechanism must first be moved, which also complicates the mechanism if the aperture control is performed automatically. However, there is a drawback that the cost is also high.

<Means for Solving Problems> The diaphragm aperture control device for the aperture-priority AE shutter of the present invention has been made in view of such problems, and it is possible to selectively set the aperture diameter and the aperture diameter. The shutter blades also function as aperture blades, which are provided with slits at positions corresponding to the respective aperture diameters on the small aperture side corresponding to the mechanical delay before reaching, the motor for opening the shutter blades, and the shutter blades in the closing direction. Equipped with a closing spring that urges and a photointerrupter that detects each of the slits during opening operation and monitors the opening state of the shutter blades, which corresponds to a mechanical delay before reaching a preset aperture diameter fn set during opening operation. The drive of the motor is stopped by the photointerrupter detecting that the shutter blade has been opened to the aperture size fn- ₁ on the small aperture side. After the shutter blade has reached the set aperture diameter fn- ₁ from the aperture diameter fn- ₁ by the inertial opening operation of the shutter blade after the driving is stopped, the action of the closing spring causes the small aperture side smaller than the set aperture diameter fn to be closed. When the photointerrupter detects the closing operation to the position, the opening operation of the motor M is performed again, and the set aperture diameter fn is maintained.

<Operation> The motor stops driving at the aperture size fn- ₁ on the small aperture side due to the mechanical delay before reaching the aperture size fn preset by the user, but the shutter blades have a closing spring due to inertia. Opening operation continues for a while against the force. Eventually, after reaching the set aperture diameter fn, the closing spring starts to act and the closing operation starts. This closing operation causes the motor to be driven again at the place where the aperture diameter is smaller than the set aperture diameter fn and becomes smaller, and the opening operation is performed toward the set aperture diameter fn. By sequentially repeating this operation, the aperture of the shutter blade can be practically maintained at the set aperture diameter fn.

<Embodiment> Hereinafter, the present invention will be described with reference to the drawings. Around the diaphragm / shutter blade used here, a plurality of slits for monitoring the opening state are provided, but regarding the positional relationship of the slits, the aperture to be preset (for example,
fn) Main slit that outputs a signal Amount corresponding to the mechanical delay before reaching the aperture diameter fn A small auxiliary aperture that issues a mechanical delay signal at the aperture diameter on the small aperture side (represented by fn- ₁ per aperture before) There is.

Referring to FIG. 1, when the motor M is pulse-driven, the shutter blade starts the opening operation, and the mechanical delay signal Pn- ₁ is detected at the aperture diameter fn- ₁ which is one before the preset aperture diameter fn. Then, the opening drive of the motor M is stopped. However, due to inertia, the mechanical aperture delays further opening and the set aperture
When it reaches fn, the set aperture diameter signal Pn is output. At this time, the closing operation of the shutter blades is started by the closing spring, and the set aperture signal Pn disappears (that is, the aperture becomes smaller than the set aperture fn), so use the disappearance of the signal Pn. When the motor M is driven again and the shutter blades are opened, the set aperture signal Pn is output again at the set aperture aperture fn, and the same operation is repeated thereafter to maintain the aperture at the desired aperture. it can.

Next, a circuit block for performing these operations will be described mainly with reference to FIG. When the shutter release switch SW ₁ is turned on by shutter release, the Q output of the latch circuit 1 becomes H (high), and the output of the comparator 3 of the known AE (automatic exposure) control circuit including the light receiving element 2 also becomes H. There is. As a result, two of the remaining three inputs of the AND circuit 4 are also H at this point, as will be understood from the later description, so that the pulse signal from the oscillator 5 appears as the output of the AND circuit 4. , The transistor T ₁ is turned on and the motor M is rotated to open the shutter blades.

The opening state of the shutter blade is monitored by a blade opening monitor 7 including the photo interrupter 6.
The counter 8 is located just before the number of set aperture pulses (n),
That is, since n-1 is set, when the mechanical delay signal Pn- ₁ just before the preset aperture diameter (by the mechanical delay) is detected by the blade opening monitor 7, the output of the counter 8 is output. It changes from L (low) to H. Then, since the Q output of the latch circuit 9 also becomes H and the latch circuit 10 is in the clear (CL) state, the output of the latch circuit 10 becomes H and the output of the NAND circuit 11 changes from H to L. As a result, the output of the AND circuit 4 becomes L, the power supply to the motor M is turned off, and the opening drive is stopped (the position of the aperture fn- ₁ ).

When the next pulse (setting aperture pulse Pn) comes in through the AND circuit 12 (because the output of the counter 8 is H at this point), the latch circuit 10 is set and the output becomes L, and the NAND circuit 11 Output changes from L to H. Therefore, the period from the mechanical delay signal Pn- ₁ to the set aperture signal Pn is a period in which the output of the NAND circuit 11 is L, and the motor is de-energized during this period.

At this time, the Q output of the latch circuit 10 is set to H by the set aperture signal Pn.
When the set aperture signal Pn disappears, the output of the inverter 13 becomes H, the output of the AND circuit 14 also becomes H, and the motor M rotates (see part B of waveform C in FIG. 1).

When the set aperture signal Pn is input again, the output of the AND circuit 14 becomes L, the power supply to the motor M is turned off, and the opening drive is stopped. By repeating the above operation, the set aperture can be maintained.

Then, when the proper exposure time is reached by a known operation, the output of the comparator 3 of the AE circuit changes from H to L, the output of the AND circuit 4 changes to L, the power supply to the motor M is turned off, and the action of the closing spring causes Shutter closes.

<Effects of the Invention> As described above, according to the present invention, the opening of the motor M is driven by the diaphragm aperture fn- ₁ on the small aperture side corresponding to the mechanical delay before reaching the preset aperture diameter fn preset by the user. Stopping and maintaining the desired set aperture size by repeating driving and non-driving at the set aperture size, the operation is quick, the mechanical part is simple, and it is convenient if it is used as a bifocal shutter. Is.

[Brief description of drawings]

FIG. 1 is a waveform diagram for explaining one embodiment of the present invention, and FIG. 2 is a circuit block diagram for realizing the same embodiment. 4,12,14 ... AND circuit, 5 ... Oscillator, 6 ... Photointerrupter, 7 ... Blade monitor, 8 ... Counter,
9,10 Latch circuit, 11 …… Nand circuit, M …… Motor, fn …… Set aperture, fn- ₁ …… Before mechanical delay.

Claims (1)

[Scope of utility model registration request] 1. A shutter blade which also serves as a diaphragm blade and is provided with slits at positions corresponding to the selectively set aperture diameter and the aperture diameter on the small aperture side corresponding to the mechanical delay before reaching the aperture diameter, respectively. A motor for opening the shutter blades, a closing spring for urging the shutter blades in a closing direction, and a photointerrupter for detecting the slits during opening operation and monitoring the opening state of the shutter blades, Drive of the motor by the photointerrupter detecting that the shutter blade has opened up to the aperture aperture fn- ₁ on the small aperture side by a mechanical delay before reaching the preset aperture aperture fn during opening operation. was allowed to stop by the inertia opening operation of the shutter blade after the drive stop reaches the diameter FN- ₁ aperture shutter blade to set aperture diameter fn Later, the set aperture diameter by the action of the closing spring
When the photointerrupter detects that the closing operation has been performed to a position closer to the small aperture than fn, the motor M is reopened to set the aperture diameter.
Aperture control system for aperture-priority AE shutters, characterized by maintaining fn.