JPS61235824A - Electromagnetically driven shutter - Google Patents

Abstract

PURPOSE:To obtain high-accuracy governing effect by building a governor mechanism on a yoke which forms part of the magnetic circuit of an electromagnetically driven shutter. CONSTITUTION:When a movable coil member 7 is powered on for a time based upon a photometric signal from a control part, the member 7 rotates clockwise and an operation pin 11 rotates the selector 13 of the governor mechanism 12 clockwise against a torsion spring 15, so that the rotating speed is governed through the inertial resistance of a flywheel 14. A shutter blade 9, therefore, maintain a specific equal speed when opening an opening part 20 to functions as the shutter blade of a programmed shutter. Consequently, the shutter blade 9 is governed effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a programmable electromagnetic drive shutter with an improved assembly structure of a governor mechanism.

[Conventional technology]

An electromagnetic shutter used as an exposure device for a camera has a moving coil member with a specific coil pattern placed in a magnetic field generated between two yoke irons with a permanent magnet in between, and the moving coil member is energized to rotate. When the shutter blade is turned on, a pin provided thereon drives a shutter blade, and by controlling the energization time, the required amount of exposure can be obtained.

When such electromagnetic shutters employ a so-called programmable shutter mechanism that determines the exposure amount by changing the aperture diameter and opening time of the shutter blades at a fixed ratio, the shutter blades are given predetermined opening operating characteristics. In order to provide this, speed regulating action is applied to the moving coil member using a governor mechanism or the like.

[Problem that the invention seeks to solve]

In the prior art, the aforementioned governor mechanism was assembled as an independent unit separate from the electromagnetically driven shutter, and by assembling it into the shutter, it was used as a speed governor for the shutter blades.

However, according to this method, since a base plate is required to form a unit, the number of related parts increases, which increases the number of assembly steps, and also causes errors in the positional relationship with the member that drives the shutter blade when assembling it to the shutter device. Therefore, in order to obtain a highly accurate speed regulating effect, delicate positional adjustment is required, although it is expensive.

As a result of solving and improving this problem, the present invention provides a programmable electromagnetic drive shutter that eliminates the need for a base plate and that can obtain a highly accurate speed regulating effect even if a governor mechanism is connected without adjustment. This is what I am trying to do.

[Means for solving problems]

The above object is achieved by an electromagnetically driven shutter characterized in that a governor mechanism is assembled on a yoke forming a part of the magnetic circuit of the electromagnetically driven shutter.

〔Example〕

An embodiment of the present invention is shown in FIG.

FIG. 1 shows an expanded structure of a shutter device 1 according to the present invention, in which a first yoke 2 and a second yoke 3 are a holding frame in which a plurality of permanent magnets 5 are equally distributed along the circumference. 4, and has a coil pattern 6a in the gap between the second yoke 3 and the permanent magnet 5, and is used, for example, to drive a photographic lens. The member 6 and a second movable coil member 7 as a shutter driving coil plate having a coil pattern 7a are arranged in a stacked manner with a slight gap between them by a spacer 7b.

Further, three shutter blades 9 are arranged and housed at equal intervals between the back surface of the second yoke 3 and the base plate 8 which is attached at a predetermined distance.

The shutter blades 9 are each pivotally supported by a shaft 9a provided in the second yoke 3, and are inserted into arc-shaped grooves 9b provided in each, penetrating through the hole 3a of the second yoke 3 for operation. The three drive pins 10 provided on the second movable coil member 7 are engaged with each other.

Further, the actuating pin 11 implanted in the second movable coil member 7
penetrates the second yoke 3 and its tip is connected to the second yoke 3.
It engages with a notch in the sector 13 of the governor mechanism 12 provided on the back surface of the governor mechanism 12.

The governor mechanism 12 includes the second yoke 3 and the second yoke 3.
The sector 13 is rotatably supported between an upper plate 16 fixed by screws to the sector 13, and a pinion 14a meshing therewith.
and an integral flywheel 14, and the sector 13 is supported by a torsion spring 15.

The notch portion 13a is kept at the position shown in the figure by being biased counterclockwise by the notch portion 13a.

Note that the torsion spring 15 is given only a weak bias that allows the sector 13 to return to its initial position and prevents the shutter blade 9 from opening naturally, so that its contribution to the inertial system of the governor is small. It is.

That is, in FIG. 1, the shutter blade 9 is located at the opening 20 of the lens.
When the second movable coil member 7 is in the closed state and the control unit energizes the second movable coil member 7 for a time based on the photometric signal, the second movable coil member 7 rotates clockwise and the actuating pin 11 rotates clockwise. rotates the sector 13 of the governor mechanism 12 in a clockwise direction against the torsion spring 15, so that the rotational speed is controlled by the inertial resistance of the flywheel 14.

As a result, the shutter blade 9 maintains a predetermined constant speed when opening the opening 20, and can perform the function of the shutter blade as a program shutter.

That is, in FIG. 1, the shutter blade 9 is located at the opening 20 of the lens.
is in a closed state, and the second movable coil member 7
When the control unit energizes for a time based on the photometric signal, the second movable coil member 7 rotates clockwise to open the shutter blade 9, and then returns to the initial position by energizing in the opposite direction. It is supposed to be done.

At this time, the amount of exposure made by the shutter blade 9 is determined by the energization time to the second movable member 7 and the maximum diameter of the shutter blade 9 that is reached within that time, and both are set at a certain ratio. When the second movable coil member 7 is operated to open, the sector 13, which is biased counterclockwise by the torsion spring 15, is rotated clockwise using the operating pin 11, and The shutter blade 9 is provided with the required opening operation characteristics by being subjected to the regulating action by the meshed flywheel 14, but is not subject to the regulating action by the governor mechanism in the closing direction. .

In this way, in the electromagnetically driven shutter of the present invention, the sector 13 and the flywheel 14 that constitute the governor mechanism 12 are
One shaft end of the is directly attached to the second yoke 3, and the other shaft end is also supported by the upper plate 16 attached directly to the second yoke 3, so that the second yoke 3 and the shaft are It is possible to accurately set the relational dimension between the second movable coil member 7, which rotates in alignment with the operating pin 11.

That is, since the actuating pin 11 is precisely aligned with the predetermined depth of the notch 13a of the sector 13, the second movable coil member 7 is moved by the flywheel 14 as it rotates. To receive a certain inertial resistance＼
Therefore, an effective speed regulating action can be given to the shutter blade 9.

Note that the second movable coil member 7 is set in an engagement relationship between the operating pin 11 and the notch 13a of the sector 13 so that the speed regulating action of the governor mechanism 12 can be applied over the entire rotation angle of the second movable coil member 7. do.

〔Effect of the invention〕

According to the present invention, the accuracy of the assembly position of the governor mechanism is improved,
As a result, an electromagnetically driven shutter can be provided which provides accurate speed regulating action without requiring adjustment.

4. Simple drawing of 1t12FIA FIG. 1 is an exploded perspective view of the electromagnetically driven shutter of the present invention.

2.3... (first, second) yoke 5... permanent magnet 6... first moving coil member 7... second moving coil member

Claims (1)

[Claims] An electromagnetically driven shutter characterized in that a governor mechanism is assembled on a yoke forming a part of a magnetic circuit of the electromagnetically driven shutter.