JPH0690381B2 - Electromagnetic shutter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention uses an elastic force of an elastic member such as a spring as a drive source for moving a shutter blade, and an electromagnetic force as a means for urging a hinge spring. The present invention relates to an electromagnetic shutter adapted to use force.

[Conventional technology]

Conventionally, various shutters using electromagnetic force have been proposed. One of them is a slit-type shutter for a camera, which uses electromagnetic force as a drive source of a shutter spring. In this, for example, a coil integrally attached to a shutter blade is positioned in a magnetic field to perform a predetermined exposure operation. However, since this shutter uses an electromagnetic force as a drive source for the shutter, there is a problem that variations in drive voltage and coil resistance directly affect shutter accuracy.

Therefore, a stable shutter accuracy is obtained by connecting an elastic member such as a spring to the shutter blade, biasing the spring with an electromagnetic force generated by energizing the coil, and controlling the timing at which the energization is cut off. There is an electromagnetic shutter adapted to obtain In this case, the moving speed of the shutter blade is substantially determined by the charge torque obtained by energizing the coil placed in the magnetic field and the moment of inertia of the moving member including the shutter blade and the like. Generally, the moving speed of this shutter blade is
Higher speed is necessary to improve the accuracy during high-speed shooting and to improve the synchronization performance between the shutter and flash during flash shooting. Therefore, conventionally, measures such as increasing the magnetic energy of the magnet or the like, increasing the number of turns of the coil and increasing the energizing current to increase the biasing torque of the spring, and the inertia of the peripheral moving member including the shutter blades are used. Consideration was given such as reducing the moment.

[Problems to be solved by the invention]

However, the moving speed of the shutter blades is improved only by the square root multiple of the spring urging torque increase rate, and the effect obtained with respect to the input energy is extremely low. Therefore, there is a physical difficulty in increasing the speed by increasing the magnetic energy of the magnet or the like, and even if the number of turns of the coil is increased and the value of the energized current is increased, a considerable number of turns and current value are required.

Further, there is a problem that the moment of inertia and strength of the moving member are in a contradictory relationship, and even if the moment of inertia is reduced, there is a limit and a sufficient effect cannot be expected.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electromagnetic shutter capable of significantly improving the moving speed of shutter blades with a small input energy.

[Means for solving problems]

The present invention relates to an electromagnetic shutter that performs exposure by causing a shutter front blade, which is connected to an elastic member that includes an electromagnetic coil and is biased in the shooting driving direction, and a shutter rear blade having the same structure to travel with a predetermined time difference, and performing exposure. Permanent magnets arranged corresponding to the electromagnetic force generated by energizing the respective electromagnetic coils of the blades and the trailing blade of the shutter, and energization control means for controlling the energization of the electromagnetic coils of the leading blade of the shutter and the trailing blade of the shutter. The energization control means energizes the electromagnetic coils of the shutter leading blade and the shutter trailing blade to hold both shutter blades in a shutter closed state against the biasing force of each elastic member. The electromagnetic coil of the shutter blade is energized in the reverse direction to start traveling of the leading blade of the shutter, and after a predetermined time delay, the electromagnetic coil of the trailing blade of the shutter is energized in the opposite direction. The configuration, characterized in that to start the running of the motor after the blade, it is intended to achieve the object.

[Action]

The electromagnetic shutter according to the present invention not only acts to keep the blades closed by the energization control means against the elastic force of the elastic member as the drive source for the movement of the shutter blades, but also at the start of the movement of the shutter blades. Since it acts to move the blades, an auxiliary force is given to the maximum static frictional force generated at the start of movement, and the shutter blades can run at high speed.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 is an exploded perspective view showing the structure of the shutter mechanism in this embodiment.

In the figure, A indicates a lower mechanism of the shutter mechanism, 1a indicates a shutter leading blade composed of a circular portion 1a ₁ and a fan-shaped portion 1a ₂ integrally extending from the peripheral edge of the circular portion 1a ₁ , and 2a indicates this shutter tip. A flat coil as an electromagnetic force generating means provided on the circular portion 1a ₁ of the blade 1a is connected to the circuit described later shown in FIG. Reference numeral 3 is a yoke having a through hole, and stoppers 3a and 3b are projected on one surface of the yoke. 4 is a yoke 3
The cylindrical bearing 5 communicated with the through hole of
A through hole 5a communicating with the through hole of the yoke 3 is formed in the center of the magnet provided on the other surface of the magnet. 6
Is a rotating shaft, and its flange portion 6a is a shutter blade
The shaft portion is inserted into the magnet 5 and the bearing 4 of the yoke 3 while being fixed to the circular portion 1a ₁ of 1a. Reference numeral 7 is a lever fixed to one end of a rotating shaft 6 inserted through the magnet 5 and the bearing 4 of the yoke 3, and the stopper 3
The rotation phase of the shaft 6 is restricted within the range of b and 3c. Reference numeral 8 is a spring as an elastic member connected to the shutter leading blade. Reference symbol B denotes a shutter upper mechanism in which a shutter rear blade 1b having a flat coil 2b having the same structure as the shutter front blade 1a is driven, and its constituent elements and the related structures of these constituent elements are substantially the same except for the magnet 5. And are shown with the same reference numerals. Further, the shutter blades 1a and 1b in the upper mechanism B and the lower mechanism A are adapted to rotate facing each other with a spacer (not shown) interposed therebetween.

FIG. 2 is a block diagram showing the circuit configuration of the energization control means C for controlling the energization of the flat coils 2a and 2b provided on the front shutter blade 1a and the rear shutter blade 1b shown in FIG. In the figure, SA and SB are electronic switches, and the switching terminals a and b have switches S ₁ . S ₂ . Positive and negative DC power supply E ₁ through S ₃ . E ₂ . E ₃ is connected. M ₁ . M ₂ is a multivibrator that switches the connection state of the electronic switches SA and SB, the input side of which is connected to the switching terminals a of the electronic switches SA and SB, respectively. T is a time constant circuit whose input side is connected to the switching terminal a of the electronic switch SA, and whose output side is the switching terminal a of the electronic switch SB and the multivibrator M ₂
Is connected to the input side of.

Next, the operation will be described.

Now switch S ₁ . When S ₃ is turned on and the positive DC power sources E1 and E3 are connected to the switching terminals a of the electronic switches SA and SB, the outputs P1 and P2 of the electronic switches SA and SB are the voltage E1 input from the switching terminal a. , E3, it rises as shown in FIG. The flat coils 2a, 2b receive the outputs from the electronic switches SA, SB to generate an electromagnetic force, and due to the relationship with the magnetic field formed by the magnet 5, the shutter blades 1a, 1b resist the elastic force of the spring 8. To rotate. As a result, each spring 8 is charged and the shutter blades 1a and 1b are held in the closed state.
Output P ₁ . When time Tc elapses from the rise of P ₂ , the switch S ₁ . S ₃ is OFF, S ₂ is turned ON, the output P ₁ descends standing.
A switching pulse is output from the multivibrator M ₁ in response to this fall, and a negative output is transmitted from the electronic switch SA in response to the power supply E ₂ . At this time, since the voltage from the power source E ₁ delayed by the time Ts by the time constant circuit T is supplied to the switching terminal a of the electronic switch SB and the input terminal of the multivibrator M2, the output P _{1 of one} electronic switch SA is supplied. The output of the other electronic switch SB is still held positive at the time of falling. Then, when Ts further elapses from this time point and the output from the time constant circuit T falls, the electronic switch SB is switched to the connection with the switching terminal b by the multivibrator M ₂ , and a negative output is sent out. . In this way, receiving the negative output sent from the electronic switches SA and SB, the flat coils 2a and 2b have springs 8
Electromagnetic force is generated in the opposite direction to that when charging. Therefore, at the same time when the holding state of each shutter blade 1a, 1b is released,
The electromagnetic force in the same direction as the elastic force of the spring 8 is applied to the shutter blades 1a and 1b.
And rotate according to these forces. At this time,
For the rear shutter blade 1b, the time Ts is
Since the traveling is started with a delay, a slit is formed between the blades 1a and 1b, and thereby exposure is performed. Further, as shown in FIG. 4, the auxiliary force is always applied to each shutter blade 1a, 1b by the electromagnetic force at the start of running when the frictional force becomes the largest, so that the running is extremely fast.
The electromagnetic force generated in the elastic force direction is the shutter blade 1
Since it only needs to generate an extremely short time before a and 1b start running, the input energy to be increased by this is very small.

As described above, in this embodiment, the electromagnetic force in the traveling direction is always generated at the start of traveling of the shutter blades. However, when it is not necessary to increase the traveling speed of the shutter blades so much, the electromagnetic force in the traveling direction is changed. The charge of the spring 8 may be simply released without generating an electromagnetic force.

For example, in the circuit shown in FIG. 2, the switch S ₂ is always turned off except when high-speed traveling such as high-speed shooting and stroboscopic shooting is required, and the flat coil 1a outputs the output shown in FIG. , 1b can also be supplied, which can further reduce the input energy.

In the above description, the case where the shutter mechanism in which the shutter blades 1a.1b rotate together with the flat coils 2a and 2b is used is described, but the present invention is not limited to the above-mentioned embodiment, and other shutter mechanisms are used. It is also applicable to the one using.

〔effect〕

As described above, according to the present invention, since the traveling speed of the shutter blades can be significantly improved with a small amount of input energy, stable accuracy can be obtained even in high-speed shooting, and for example, opening / closing of the shutter and light emission during flash shooting can be performed. The tuning performance can be improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a shutter mechanism applied to an embodiment of the present invention, FIG. 2 is a block diagram showing an energization control circuit for energizing the flat coil shown in FIG. 1, and FIG. FIG. 5 is an output waveform diagram of what is shown in FIG. 2, FIG. 4 is a diagram showing the relationship between load torque and time for a flat coil, and FIG.
The figure is an output waveform diagram when the switch S ₂ in the circuit of FIG. ₂ is always turned off. 1a: Front blade of shutter 1b: Rear blade of shutter 2a, 2b: Flat coil as electromagnetic force generating means C: Energization control means

Claims (1)

[Claims] 1. An electromagnetic shutter for exposing a shutter leading blade and a shutter trailing blade having the same structure, which are connected to an elastic member for biasing the traveling at the time of photographing, with a predetermined time lag to perform exposure. Permanent magnets arranged to generate a rotational force on the shutter blades by electromagnetic force generated by energizing the respective electromagnetic coils of the shutter leading blades and the shutter trailing blades, and each of the shutter leading blades and the shutter trailing blades. An energization control unit that controls energization to the electromagnetic coil is provided, and the energization control unit energizes the electromagnetic coils of the shutter leading blade and the shutter trailing blade to electromagnetically force both shutter blades against the biasing force of each elastic member. Then, the shutter is closed and the shutter front blade is driven by the electromagnetic force in the reverse direction to switch the energization to the electromagnetic coil of the shutter front blade in the reverse direction during shooting. Is started, the electromagnetic shutter, characterized in that to start the running of the trailing shutter blade by reverse electromagnetic force to switch the energization of the electromagnetic coil of the trailing shutter blade delayed a predetermined time in the opposite direction.