JPS58200220A - Electromagnetic driving shutter - Google Patents

Abstract

PURPOSE:To obtain always a correct exposure and prevent a change of exposure amount owing to the variations of a posture, by making a rotary shutter drive at a position closer to an engaging member than the position at the time of the first feeding. CONSTITUTION:When a power feeding started, a rotary shutter 2 is rotated in the clockwise direction against a spring 3 and its end surface 2b is brought into contact with a click part 5b of a releasing lever 5, and thereby the engagement of a click part 8c of a locking lever 8 and the first locking part 5b of the releasing lever 5 is released, and the lever 8 is rotated in the counterclockwise direction by a spring 11 until its arm 8f is brought into contact with a holding part 13d of a charging plate 13. A set plate 12 runs in the left direction by a spring force by rotation of the lever 8. A charging plate 13 starts to run in the left direction by spring force while receiving action of a governor mechanism. Thereby, an AF mechanism starts to act, and an operation of distance finding and a putting-in of photographic lens are performed, and at the same time the photographic lens is stopped at a focussing position through an electromagnet and its operation is ended.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an electromagnetic drive shutter, in particular, a shutter that controls the opening and closing of a blade member by moving a coil arranged in a magnetic field to determine the exposure amount, and also controls the exposure amount by moving the coil. The present invention relates to an electromagnetically driven shutter that initiates an operation to be performed, such as a focusing operation.

Previously, the present applicant proposed that the first
The second power supply starts the automatic focus adjustment mechanism (hereinafter referred to as AP mechanism), and the member that locks the sector lever interlocked with the blade member can be released, and the second power supply to the coil starts. In Japanese Patent Application No. 56-91877, an electromagnetic drive shutter was proposed in which the blade members were opened and closed by releasing the sector lever. According to this electromagnetic drive shutter, the electromagnetic driving force generated in the gerotor by power supply to the coil is applied only to the AF mechanism during the first power supply, and only to the blade member during the second power supply. This makes it possible to ensure each operation.

By the way, in such an electromagnetically driven shutter, a relatively large force is required to release the tension of the AF mechanism at the first power supply, so the stroke until the rotor releases the tension is increased. It is necessary to configure the structure so that the tension is released when the rotor reaches a high speed and its impulse becomes large. In addition, in the electromagnetic drive shutter proposed earlier, the rotor returns to the initial position when the first power supply is stopped, so when the second power supply is performed, the rotor will move until the sector lever is released. The strokes were getting bigger as well.

However, releasing the sector lever does not require much force, so if it is done as described above, after the sector lever is fully unlocked by the second power supply, the rotor when it collides with the stopper. The speed of the rotor was not high, so the amount of bounce of the rotor at that time was also large.

Therefore, with the previously proposed electromagnetic shutter, when completing exposure in a short time, there was a strong possibility that the power supply would be stopped while the rotor was bouncing. If the power supply is cut off during the bounce, the rotor speed at that time becomes the initial speed of the rotor's subsequent movement in the closing direction, so the rotor position will not change after a predetermined period of time after the power supply stops. The contact position with the sector lever, which is moving in the opening direction by the spring force, changes. The sector lever starts moving in the closing direction when it comes into contact with the rotor, so in the case described above, the timing at which the sector lever starts closing the blade member changes and proper exposure cannot be obtained. The speed of the rotor during bounce changes depending on the magnitude of the torque component of the gravity acting on the rotor, and therefore changes for each shooting posture, so when opening and closing the blade member in a short time, Differences in posture also caused the exposure amount to change.

The present invention was developed in view of these circumstances, and its purpose is to always maintain an appropriate amount of exposure without changing the timing at which the rotor starts closing the blades when the blades are opened and closed in a short period of time. It is an object of the present invention to provide an electromagnetically driven shutter in which operations other than exposure operations can be controlled by the rotor.

Hereinafter, the present invention will be explained in detail based on embodiments shown in the drawings.

In FIG. 1, 1 is a shutter base plate, 2 is a rotor having coils 2' shown in FIG. , are biased counterclockwise by spring 3. Reference numeral 4 denotes a sector lever rotatably supported coaxially with the rotor 2, and its first and second arms have elongated holes 7a', shutter blades 7a and 7b, which also serve as multiple diaphragm blades.
Bottles 4d and 4e that fit into 7b' are implanted. 4
b is a pawl portion that comes into contact with the end surface 2c of the rotor 2 and restricts clockwise rotation of the sector lever 40. Reference numeral 5 denotes a release lever that is supported coaxially with the rotor 2, and has a tenth locking portion 5b and a twentieth locking portion 5c.
It has a claw portion 5d that comes into contact with the end surface 2b of the. Reference numeral 6 denotes a spring supported in the illustrated state by a shaft supporting the release lever 5. One arm of this spring 6 engages with the claw portion 4a of the sector lever 4, biasing the sector lever 4 clockwise and , the other arm engages with the claw portion 5a of the release lever 5, urging the release lever 5 counterclockwise.

The shutter blades 7a and 7b are rotatably supported by bins lb and lc (see Fig. 2) planted in the shutter base plate 1, and are connected to the sector lever 4 through long holes 7a' and 7b'. Rotation is transmitted so that clockwise rotation of the sector lever 40 operates in the opening direction, and counterclockwise rotation operates the sector lever 40 in the closing direction.

Reference numeral 8 denotes a locking lever rotatably supported by a shaft 1e mounted on the shutter base plate 1, which is biased counterclockwise by a spring 9, and is also attached to the tenth locking portion 5b of the release lever 5. It also has a claw portion 8c that engages with the second locking portion 5c.

When this claw portion 8c is engaged with the tenth locking portion 5b or the second locking portion 5c, the engaging piece 4c of the sector lever 4
It is located within the operating range of , and can be engaged with the engagement piece 4c.

Reference numeral 10 denotes a holding lever having a claw portion 10b that can be fitted into the groove 2a of the rotor 2; one arm 11 engages with the claw portion 8d of the locking lever 8; the other arm is the claw portion 10 of the holding lever 10;
A is a spring that urges the holding lever 10 clockwise by engaging with the holding lever 10, and is supported in the illustrated state by a shaft 1e that rotatably supports the holding lever 10. Further, the locking lever 8 has a claw portion 8b that restricts the clockwise rotation of the holding lever 100.

A claw portion 8e that engages with the locking piece 12c of the set plate 12.

An arm 8f that comes into contact with the holding portion 13c of the charge plate 13 is provided.

The set plate 12 is a pin 1d planted in the shutter base plate 1.
While being slidably supported by the locking lever 8 and biased in the direction of the arrow by a spring (not shown), in the state shown in FIG. Movement in the direction of the arrow is restricted. Charge plate 13 is set plate 1
2, it is slidably supported by the pin 1d and is biased in the direction of the arrow by a spring (not shown), and when the set plate 12 is released, it moves in the direction of the arrow. It is designed to operate an AF mechanism (not shown).

A governor mechanism (not shown) acts on the charge plate 13 so that it slides at a speed slower than the sliding speed of the set plate 12.
It is held in the position shown in FIG. 1 by engaging with the second engaging portion 12b. Further, the set plate 12 is charged by a motor (not shown) in the opposite direction of the arrow in conjunction with the hoisting operation, and at this time, the claw portion 13b of the charge plate 13 is pressed against the engaging portion 12b. It is especially charged.

14a and 14b are coils 2' (
This is a permanent magnet for applying a magnetic flux to the yoke (see FIG. 6), and a magnetic field is formed by the front yoke 15 and rear yoke 16 made of soft iron. The rotor 2 is located between the magnets 14a, 14b and the front yoke 15. The magnets 14a and 14b are fitted into the positioning holes 1e of the shutter base plate 1, and the negative side faces the rear side.

- It is crimped and fixed to the hook 16. Magi, magnet 14a,
14b is magnetized in the thickness direction, and the magnetized directions are shown opposite to each other. This is coil 2 of rotor 2.
This is because the current direction of the coil 2 is different between the part facing the magnet 14a and the part facing the magnet 14b.
When power is supplied to ', an electromagnetic driving force is applied to prevent the rotor 2 from rotating clockwise.

17 is a cover that presses the shutter blades 7a and 7b, 18
is a support plate that supports the shaft of the sector lever 4, and is fixed to the front yoke 15. 19 is an electrical insulating member, and 20 is a stopper fixed to the shaft 1f of the shutter base plate 1 via the insulating member 19, which restricts the counterclockwise rotation of the locking lever 8, and also controls the locking lever 8. When it comes into contact with 8, it becomes electrically conductive. That is, the locking lever 8 and the stopper 20 form a switch, and this switch is used as the count start switch S in FIG. 6.

Next, FIG. 6 shows the control circuit of this embodiment. In this figure, Q is the power supply battery, and sl is connected to the terminal S in response to the camera release operation, and from b to terminal S1a.
The release switch T is switched to the coil 2' from when the release switch S8 is switched to the terminal Sla side.
This trigger circuit T is configured to stop supplying power to the coil 2' after a predetermined time determined by a resistor R8 and a capacitor C1. S, terminal S2 connected to trigger circuit T
This switch S has a terminal S2b connected to the exposure control circuit E. When the charge plate 130 that operates the AF mechanism completes the travel, the charge plate 13 connects the terminal S to the terminal S2b. Can be switched.

The photoresistive element CdS charges the capacitor C3 according to the incident light from the subject. When the potential of the exposure control circuit E and the capacitor C1 reaches a predetermined value, the coil 2'
It is like controlling the exposure by stopping the power supply.

The Tr is turned off to start charging the capacitor 02 when the aforementioned count start switch S is turned on, and its base is connected to the switch S through the resistor R3.
Connected to 3. Also, R2 is the power supply Q and the switch S
, is a resistor connected between .

Note that after the first power supply by the trigger circuit T is completed, the second power supply by the exposure control circuit E is started by switching the switch island to the terminal Sab side.

Next, the operation of this embodiment will be explained based on FIGS. 2 to 5.

FIG. 2 shows the photographing preparation completion state of this embodiment, and from this state to the release switch S shown in FIG.

When the terminal is switched from terminal S to terminal Sla according to the release operation, coil 2 is first connected by trigger circuit T.
' is started, the rotor 2 rotates clockwise against the knob 3, and its end surface 2b comes into contact with the claw portion 5d of the release lever 5. With this, the release lever 5 is moved to the rotor 2.
At the same time, the locking lever 8 rotates clockwise, so that the engagement between the claw part 8C of the locking lever 8 and the tenth locking part 5b of the release lever 5 is released, and the locking lever 8 is rotated clockwise by the spring 11. 8f
rotates counterclockwise until it abuts against the holding portion 13d of the charge plate 13. Due to this rotation of the locking lever 8, the engagement between the claw portion 8e of the locking lever 8 and the engagement piece 12c of the set plate 12 is released. The vehicle travels to the left (in the direction of the arrow), resulting in the state shown in FIG. As a result, the engagement between the claw portion 13b and the engaging portion 12b of the charge plate 13 is released, so that the charge plate 13
starts running to the left in the figure (in the direction of the arrow) due to the spring force while receiving the action of a governor mechanism (not shown).

In conjunction with the movement of the charge plate 13, an AF mechanism (not shown) also starts operating, performs distance measurement operations and retracts the photographic lens, and stops the photographic lens at the in-focus position via an electromagnet (not shown). Complete the action.

On the other hand, as the rotor 2 rotates clockwise, the engagement between the claw portion 1'Ob of the holding lever 10 and the end surface of the rotor 2 is released, so that the holding lever 10 is rotated clockwise by the spring 11. The claw portion 11b is rotated by the groove sza of the rotor 2.
At the same time, the side surface thereof comes into contact with the claw portion 8bKfi of the locking lever 8.

Further, after a delay time determined by the resistor R1 and the capacitor C1 in FIG. 6, the trigger circuit T stops supplying power to the coil 2', so the rotor 2 is rotated counterclockwise by the spring 3. Note that the delay time determined by the resistor R0 and the capacitor C1 is determined by the charge plate 1.
3, the arm 8f of the locking lever 8 and the charge plate 13
Since the time required until the contact with the holding portion 13b is released is also set short, when the first power supply by the trigger circuit T is stopped, the locking lever 8 is held in the position shown in FIG. 3. ing. Therefore, when the release lever 5 rotates counterclockwise in conjunction with the rotor 2, the claw portion 8 of the locking lever 8
c engages with the second retaining portion 5c of the release lever 5.

Further, after the first power supply is stopped, the rotor 2 is moved to the groove portion 2.
When a engages with the claw portion 10b of the holding lever IO, the holding lever IO does not return to the initial position before power supply, and enters the state shown in the fourth figure. At this time, the end surface 2b of the rotor 2 faces the claw portion 5d of the release lever 5 with a slight gap therebetween. Further, when the rotor 2 rotates clockwise due to the first power supply to the coil 2', the arm 4c of the sector lever 4 engages with the claw portion 8c of the locking lever 8, and the spring 6 Since the shutter blades 7a and 7b, which are opened and closed by the sector lever 4, do not open or close, the charge plate 13 does not rotate clockwise even after the AF mechanism has completed its operation. Travel is performed under the action of the governor mechanism, and when the travel is completed, the steps shown in Fig. 6 are shown.
Itchi S.

is switched from the terminal S side to the terminal Sgb side, and the second power supply to the coil 2' is started via the dew a ratio control circuit E. As a result, the rotor 2 rotates clockwise again from the position shown in the fourth figure, and presses the end surface 2b of the rotor 2 against the claw portion 5d of the release lever 5 when the rotor 2 rotates slightly. As a result, the release lever 5 rotates clockwise, and the second engagement portion 5
C is disengaged from the claw portion 8c of the locking lever 8. The unlocked locking lever 8 is rotated counterclockwise by the spring 9, and the claw part 8c'f: is moved away from the operating area of the arm 4C of the sector lever 4, and the claw part 8C and the arm 4C are moved. At the same time, the claw portion 10b of the holding lever 10 is retracted from the groove portion 2a of the rotor 2. Nose, locking lever 8
The rotation of is stopped when its one side comes into contact with the stopper 20, but at this time, the locking lever 8 and the stopper 20 are in a conductive state, and the rotation of the locking lever 8 and the stopper 20 is stopped. Count start switch S in Figure 6
, is turned on. As a result, the transistor Tr is turned off, and the capacitor C8 can be charged with a current corresponding to the subject light generated in the photoresistance element CdS.

Also, at this time, as mentioned above, the sector lever 4 is moved to the arm 4.
Since the engagement of c has been released, clockwise rotation by the spring 6 is started, and the shutter blades 7a and 7b are opened. As a result, a film (not shown) is exposed, and when the charging voltage of the capacitor C8 reaches a predetermined value and proper exposure can be obtained, the exposure control circuit E stops the second power supply to the coil 2'. At this time, the rotor 2 starts to move back by the spring 3. Due to this backward movement of the rotor 2, the end surface 2C of the rotor 2
When B&C collides, the biasing force of spring 6 is smaller than the biasing force of spring 3, so the sector lever 4 starts rotating counterclockwise, and the shutter blade? a and 7b in the closing direction to complete the exposure operation. This state is shown in FIG.

Thereafter, when the charging plate 12 is started to be charged (moved to the right in the figure) by a motor (not shown), the claw portion 13b of the charging plate 13 is pushed by the engaging portion 12b, and the locking lever 8 is also pressed. When the claw portion 8d contacts the engaging portion 12c, it is rotated clockwise and returns to the state shown in FIG. 2.Thereby, the claw portion 8e is again engaged with the engaging portion 12c. This means that the entire device is in its initial state.

In this example, after the first power supply was stopped, the rotor 2 was held in the position shown in FIG. 4 by the holding lever 10. It is also possible to hold That is, without completely stopping the current even after the first power supply, a predetermined electromagnetic driving force is applied to the rotor 2, and this electromagnetic driving force and the rotor 2
This is a method of stopping the rotor 2 at a predetermined position based on the relationship with the spring force that biases the rotor 2. According to this method, mechanical members such as the holding lever 10 can be omitted, and the structure of the shutter itself can be simplified and made smaller.

As described above, the present invention provides an electromagnetic drive shutter in which a first power supply starts, for example, a focusing operation, and a second power supply starts an exposure operation, which includes a rotor driven by the power supply, and a loader. The locking member that starts each of the above-mentioned operations is tightened in conjunction with the above, and at the time of second power supply, the rotor is driven from a position closer to the locking member than during the first power supply. As a result, the focus adjustment operation can be performed reliably, and the amount of bounce of the rotor during the exposure operation can be reduced. For this reason, even when completing an exposure at a high speed,
There is no risk that the second power supply will be stopped during the bounce of the rotor, the initial speed of the return operation of the rotor will change, and the opening characteristics of the blade member will fluctuate. That is, according to the present invention, the aperture characteristics of the blade member can be made constant, and in such an electromagnetically driven shutter, proper exposure can always be obtained, and changes in the amount of exposure due to differences in posture can also be prevented. I can do it.

Furthermore, according to the present invention, it is also possible to reduce the current dependence of the time from the start of power supply to the start of exposure during the second power supply.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing one embodiment of the electromagnetic drive shutter of this invention, Figs. 2 to 5 are plan views showing the operating states of the main parts in this embodiment, and Fig. 6 is this embodiment. FIG. 2 is a wiring diagram showing a control circuit of FIG. 2... Rotor, 4... Sector lever, 5...
...Release lever, 7a, 7b...Shutter blade, 8
...Lock lever, 10...Holding lever, 12...
・Set plate, 13... Charge plate, 20... Stopper, T... Trigger circuit, E... Exposure control circuit, 'Sl... Count; start non-switch. Applicant Canon Co., Ltd.

Claims (2)

[Claims] (1) In an electromagnetic drive shutter in which the first power supply starts the camera's exposure preparation operation and the second power supply starts the exposure operation, there is a rotor driven by each of the above-mentioned power supplies, and this rotor. An electromagnetically driven shutter, characterized in that, during a second power supply, the rotor is driven from a position closer to the locking member than during the first power supply. (2) The holding member for holding the rotor in a predetermined position at the start of the second power supply is capable of engaging with the rotor in response to the first power supply. ) The electromagnetic drive shaft described in section 9.