JPS61251828A - Shutter device - Google Patents

Abstract

PURPOSE:To obtain the stable, high-precision quantity of exposure by letting a current to an electromagnetic device in such a direction that a shutter is closed firstly and then in a shutter closing direction, and thus operating the shutter. CONSTITUTION:The shutter blade 9 of a shutter device 1 is initially restrained at a position where the pin 10 of the 2nd moving coil member 7 abuts on an end part of the hole 3a of the 2nd yoke 3, and held at the position with the energizing force of the torsion spring 15 of a governor mechanism 12. Then, a current is flowed reversely to the 2nd moving coil member 7 prior to exposure and the member 7 is energized counterclockwise to return the shutter blade 9 which leaves the initial position freely owing to vibration, etc., to its normal start position. Then, an opening part 20 is opened on the basis of a light measurement result by feeding electricity to the member 7 from a control part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electromagnetically driven direct-left two-beam shutter device that stabilizes exposure time.

[Conventional technology]

Program shutter control methods can be broadly classified into two types. One is the post-diaphragm method that has been commonly used in the past, and the other is called the direct drive method. In the rear aperture method, the shutter blade that also serves as the diaphragm has an opening separate from the exposure opening, and this opening is used to photoelectrically detect the aperture speed, etc. when the shutter blade opens. However, this information is fed back to the control circuit to control the energization time to the electromagnet etc. so that proper exposure operation can be performed. Therefore, in the case of multiple aperture method,
Even if there is slight variation in the aperture speed of the shutter blades, it has the advantage that it does not greatly affect the exposure accuracy, which is equipped with a feedback system. This has the disadvantage that circuits and the like are added to the shutter mechanism, making it complicated.

With the direct drive method, the aperture speed of the shutter blades is set first, and the appropriate exposure is obtained by adjusting the aperture speed to the shutter drive device and the subject brightness. □All energizing times are determined first, and each energizing time is adjusted according to the subject brightness. This is stored in the control circuit as data corresponding to .

Therefore, in actual photography, when the brightness of the subject is detected by a photometric circuit, the energization time is automatically retrieved as data corresponding to the subject brightness, and the shutter opening is determined by the energization time.

In this direct drive method, as mentioned above, the opening speed was assumed to be constant when determining the energization time to the Nyatta drive device, but in reality, adjusting the opening speed to a constant value is different from the conventional mechanical shutter. However, it was extremely difficult to do so, and we had no choice but to adopt the multiple aperture method, even though it was somewhat mechanically complex. However, in recent years, an electromagnetic drive device that combines a permanent magnet and a printed coil has been developed, making it possible to freely control the speed by adjusting the direction and amount of current flowing to the printed coil.This electromagnetic drive device can be used as a shutter. By applying this method, the difficulties of the direct drive method were solved. Moreover, since the control system of the direct drive method can be performed entirely in the form of data processing, control technology such as microcomputers can be applied, and the direct drive method has been reconsidered even more. An electromagnetic device used as a direct drive shutter device for a camera places a moving coil member with a specific coil pattern in the magnetic field generated between two yokes sandwiching a permanent magnet. When the movable coil member is energized and rotated, a bottle provided thereon drives a shutter blade,
By controlling the energization time, the required exposure amount can be obtained. In such a shutter device,
When the movable coil member and the shutter blade return to their initial positions after exposure, the current is cut off, so there is no action to force them to return to their initial positions, resulting in an unstable state. Therefore, in general, a spring or the like is provided that is weak enough to maintain the movable coil member in its initial position without significantly affecting the operation of the movable coil member.

In the present invention, as a substitute for the spring force for stabilizing the initial position, the restoring force of a governor provided as a speed regulating mechanism for making the shutter opening characteristic triangular waveform is utilized.

[Problem that the invention seeks to solve]

As is well known, the restoring force of the governor mechanism itself that interlocks with the movable coil member is extremely weak, and if this spring is strong, it will adversely affect the opening characteristics of the shutter, so a spring with a weak urging force is used. Therefore, in this case as well, instability of the initial position of the shutter blade is unavoidable, and it is inevitable that the initial position of the shutter blade will fluctuate slightly due to shock or the like. The shutter blade is in the initial position fIit
Since the opening is closed and the opening is placed in a position with more room, there is no risk of light leakage even if the position changes slightly as mentioned above. This is because the exposure amount control in the dog-type program shutter is performed only by the energization time to the OT moving coil member determined by the exposure control section.

If there is a change in the initial position of the movable coil member, the amount of aperture formed by the shutter blades linked to the movable coil member changes, resulting in different exposures even for objects of the same brightness.

In other words, as mentioned above, the direct drive type program shutter has the factors that make the exposure accuracy unstable, and we have solved this problem and improved it by creating an electromagnetic system with good exposure accuracy and a constant initial position of the shutter blade. The present invention attempts to provide a shutter device that is driven.

[Means for solving problems]

The above object is to provide a shutter having an electromagnetic device that changes the direction of movement of the shutter according to the polarity of an input current. This is achieved by a shutter device that operates the shutter by causing a flow of

〔Example〕

An embodiment of the invention is shown in FIGS. 1, 2, and 3.

FIG. 1 shows an expanded structure of the shutter device tl of the present invention, in which a first yoke 2 and a second yoke 3 hold permanent magnets 5 of several bubbles evenly distributed along the circumference. They are provided facing each other with a frame 4 interposed therebetween, and have a coil pattern 6a in the gap between the second yoke 3 and the permanent magnet 5, which is used to drive and/or control a photographic lens, for example. A first moving coil member 6 and a second moving coil member 7 as a shutter driving coil plate having a coil pattern 7a are arranged in a stacked manner with a slight distance 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 a base plate 8 attached at a predetermined distance.

The shafts 9a fixed to each of the shutter blades 9 are pivotally supported in holes provided in the second yoke 3, and the holes 3a of the second yoke 3 are inserted into arc-shaped grooves 9b provided in each of the shutter blades 9. Three drive pins 10 provided on the second movable coil member 7 that penetrate and operate 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 sector 13 of governor machine $12, which is provided on the back side of governor machine $12.

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, both of which are kept constant. When the second movable coil member 7 is actuated, the actuation pin 1
1, the sector 13, which is biased counterclockwise by the torsion spring 15, is rotated clockwise and subjected to the regulating action by the flywheel 14 meshed therewith. It is designed to provide an open operating characteristic of.

The initial position of the shutter blade 9 in the shutter device 1 is such that the pin 10 of the second driving coil member 7 is in the second position.
It is regulated at a position where it abuts one end of the hole 3a of the yoke 3, and is maintained at that position by the biasing force of the torsion spring 15 of the governor mechanism 12. In order to further ensure its effect, prior to exposure, the second movable coil member 7 is biased counterclockwise by passing a current in the opposite direction, and the shutter blade 9, which has been separated from its initial position due to vibration etc., is After returning to the normal starting position, the opening is opened based on the photometry result by energization from the control section.

FIG. 2 shows a drive circuit for the second movable coil member 7, and FIG. 3 shows the operating timing of this circuit. When a signal as shown in Fig. 3 is input to the terminal, the transistors TR and TR
, becomes conductive and moves the movable coil 1 M in the opposite direction.
The shutter blade is driven in the closing direction, and when a signal is input to the terminal B, the transistors TR, , TR, are made conductive and the movable coil M is driven in the positive direction, that is, in the direction of opening the shutter blade. That is, a driving force in the closing direction acts on the shutter blade for a time of TI, urging the shutter blade to the initial position, and then a driving force in the opening direction acts for a time of T, causing the shutter to open. done, then time,
At T3, a driving force in the closing direction is applied, and the shutter blades are closed.

〔Effect of the invention〕

According to the present invention, an electromagnetically driven shutter device is provided which can obtain a highly accurate and stable exposure amount using a program based on a photometric signal.

[Brief explanation of the drawing]

2.3... (first, second) yoke 5... permanent magnet 6... first moving coil member 7...
...Second moving coil member 8...Base plate
9...Shutter blade 9a...Axis
, 9b...*10... Drive pin
11... Operating pin 12... Governor mechanism

Claims (2)

[Claims] (1) In a shutter having an electromagnetic device that changes the direction of movement of the shutter depending on the polarity of the input current, first a current is passed through the electromagnetic device in the direction of closing the shutter, and then the direction of movement of the shutter is passed in the direction of opening the shutter. A shutter device that operates a shutter by passing an electric current. (2) The shutter device according to claim 1, wherein the control device controls the shutter to determine the shutter opening time according to a program built into the control device.