Photographic Apparatus With Electrically Operated Focal Plane Shutter

Abstract

A focal plane shutter for photographic apparatus has front and rear shutter curtain release mechanisms, a shutter release device which is movable from a starting to an operative position to thereby actuate the front shutter curtain release mechanisms, a selector knob which is turnable between a first position to thereby set the shutter for bulb exposure operation and several additional positions to thereby set the shutter for operation with different preselected exposure times, an electric circuit including an electromagnet which is deenergized with a preselected delay following depression of the release device to thereby cause or permit actuation of the rear shutter curtain release mechanism and which remains deenergized in the first position of the selector knob because the electric circuit is then deenergized by a contactor which rotates with the selector knob, and an actuating device which actuates the rear shutter curtain release mechanism in response to movement of the release device back to its starting position while the selector knob dwells in the first position. The consumption of energy is reduced to zero when the selector knob dwells in such first position because the circuit of the electromagnet is then deenergized.

Description

This invention relates to an electrically operated focal plane shutter mechanism for a camera provided with a bulb exposure device.

A conventional focal plane shutter mechanism is so constructed that actuation of a rear shutter curtain or diaphragm is brought about after a certain time delay following the time of actuation of a front shutter curtain or diaphragm, such time delay corresponding to the time constant of the time-delay circuit inserted in an electric circuit included in the electric exposure device. The current supplied from the current source of the electric circuit inserted in the electric exposure device is fed to and energizes an electromagnet, which then acts to actuate a movable member by the magnetic suction effect so as to release the rear shutter diaphragm. When the bulb exposure must be resorted to, as for instance when photographing at night or in a dark place, the electromagnet has to be energized for an extended period of time, such as several minutes, so that the battery serving as the current source is used up due to the prolonged discharging time.

With the foregoing drawback inherent in the conventional focal plane shutter mechanism, the main object of the present invention is to provide a mechanism wherein the connection from the current source to the electromagnet is interrupted at the time of the bulb exposure operation for reducing as much as possible the consumption of current.

Another object of the present invention is to provide a focal plane shutter mechanism of the abovementioned kind wherein the latch members adapted for use with the rear shutter diaphragm may be dispensed with expect for a latch member engaging with a projection on a gear operatively associated with the rear shutter diaphragm.

Still another object of the present invention is to provide a focal plane shutter mechanism of the abovementioned kind which is simple in construction and can be mass-produced.

These and other objects of the present invention will become more readily apparent upon perusal of the following detailed description thereof especially when read in conjunction with the accompanying drawing.

In the drawing;

FIG. 1 is a front elevational view of certain parts of the novel focal plane shutter mechanism for use with a bulb exposure device, the shutter mechanism being set for the bulb exposure operation;

FIG. 2 is a side elevational view as seen from the right-hand side of FIG. 1;

FIG. 3 is a front elevational view similar to that of FIG. 1 wherein the bulb exposure operation is being enacted;

FIG. 4 shows the parts of the shutter mechanism in the view of FIG. 1, but set for the normal exposure operation other than the bulb exposure operation; and,

FIG. 5 is a view as seen from the right-hand side of FIG. 4.

Referring to the accompanying drawing, a release device including a button 1 is mounted on a camera housing only schematically shown at 2 in FIG. 1. A rod 3 of the release device is secured at one end to the release button 1 and formed with an actuating projection 4 at the other end for engagement with one end of a lever 5 which forms part of the front shutter curtain release means and is pivotally mounted at 6 on said camera housing 2.

The other end of said lever 5 engages in turn with one end of a latch member 7. When the release button 1 is not depressed, the other end of the latch member 7 engages with a projecting part 9 of a gear 8 and the front shutter curtain or diaphragm is not set into actuation.

Once the release button has been depressed, to leave its starting position and to move toward the operative position of FIG. 2 the lever 5 is pivoted clockwise by its engagement with the projection 4 on the rod 3 and the latch member 7 is pivoted counterclockwise for disengaging the latter from the projecting part 9 of gear 8. When the gear 8 has thus been released from engagement with the latch member, it is caused to rotate so as to set the front shutter diaphragm, not shown, into actuation through a counter gear 10 and a pinion 11 in a known manner.

A further gear 12 mounted on the camera housing 2 coaxially with said gear 8 forms part of release means for the rear shutter curtain or diaphragm and has a projecting part 13 engageable by one end of a further latch member 14 pivoted at 15 and urged to rotate counterclockwise under the force of a spring 16 which acts for normally releasing the gear 12 from engagement with the one end of the latch member 14 and actuating the rear shutter diaphragm, not shown. The other end of the latch member 14 mounts a metallic plate 17 which is attracted towards the iron core of an electromagnet 18 when the latter is energized.

A shutter dial or selector 19 is rotatably mounted on the camera housing 2 by shaft 19' having a rectangular cross-section and cooperates with a graduation 20 corresponding to the desired shutter speeds, such as B, 1, 1/10, 1/30. 1/50, 1/100 second, in a known manner.

On a stationary part of the camera housing 2, a series of resistances R.sub.1, 1, r.sub.2, R.sub.n are arranged in a semicircle for registry with the abovementioned graduation 20 and provided with the respective terminals 21 for electric connection with a contactor 22 formed with a metallic disc 22' affixed on the shutter dial 19.

When the dial 19 is turned manually and the contactor 22 contacts the terminals 21 in a sequential order, the current supplied from the current source 23 through the time-delay circuit 24 is fed to the electromagnet 18 in such a way that the rear shutter diaphragm, not shown, may be actuated after a predetermined time-delay corresponding to the design value of the shutter speed, in a well-known manner. A circuit de-energizing or bulb changeover device 25 has a switch disc 26' mounted coaxially with the shutter dial 19 for rotation therewith and at the axially spaced apart relation with the shutter dial 19. Said disc 26' has a contactor or projection 26 and is partly surrounded by a semicircular terminal segment 27. The projection 26 connects the ring 26' with the current source 23 by way of the segment 27 at the time of the electric exposure operation to energize the circuit 23, 24, 18.

There is mounted a contacting piece 28 which is connected through a connection lead with the electric circuit 24 on one side and slidingly contacted with the metallic disc 26 on the other side.

Numeral 29 denotes a further contacting piece mounted on a stationary part of the housing 2 and adapted for sliding contact with the metallic disc 22' for establishing an electric connection with the time-delay circuit 24. Numeral 30 denotes a bulb changeover cam mounted coaxially with said shutter dial 19 and disc 26. Numeral 31 denotes a deactivating or bulb changeover lever associated operatively with said changeover cam 30 and urged to rotate clockwise as viewed in the drawing under the force of a spring 32. Numeral 33 denotes a stopper for said lever 31, and numeral 34 denotes a driven member here shown as a link lever which forms part of actuating means for the rear shutter curtain release means 12--14 and may be depressed against the force of a helical spring 35 and is provided with an elongated slot 37 engageable by a shaft 36 mounted on the camera housing 2.

There is a further spring 34' which acts upon said link lever 34 for pivoting the lever 34 counterclockwise as viewed in FIGS. 2 and 5 with shaft 36 as its center. Said link lever 34 is formed with a groove 38 at its lower part for engagement with one end of a driving member of the release device here shown as a bifurcated lever 39 which is pivotably mounted on a shaft 41 on the camera housing 2 and abuts against a further projection 40 on the rod 3 secured to the release button 1. Numeral 42 denotes a torsion spring coiled about shaft 41, and numeral 43 denotes a leaf spring secured to the upper part of the driven lever 34. Said leaf spring acts on the metallic plate 17 so as to retard the actuation of the rear shutter diaphragm at the time of the bulb exposure operation as will be later described. Numeral 44 denotes a plate attached to the uppermost part of the lever 34 for engagement with the inclined foremost part of a projecting piece 45 mounted on the disengaging lever 31.

The numeral 46 denotes a stopper for driven lever 34, numeral 47 is a projecting part formed on the cam 30, and numeral 48 is a projecting part on the disengaging lever 31 which comes into abutting contact with the projecting part 47 on the cam 30 only at the time of the bulb exposure operation.

The operation of the parts so far shown and described is as follows:

When photographing in a dark place, and a longer exposure time is required, shutter dial 19 is turned manually and set to the first or bulb exposure position B on the graduation 20, so that the disc 26' as well as the contactor 26 is now moved to an "off" position wherein the supply of current from the current source 23 to the electromagnet 18 is interrupted. With the shutter dial thus set to the B position, the shutter is cocked. Then, the film is advanced and the release button 1 depressed manually.

The rod associated with the release button 1 is moved towards the left as viewed in FIG. 1 and the projection 40 now acts on the lever 39 so as to rotate the latter about shaft 41, and depress the link lever 34. The leaf spring 43 secured to the uppermost part of the lever 34 depresses the metallic plate 17 towards the electromagnet 18 for bringing the free end of the latch member 14 into contact with the projection 13 of the gear 12. On the other hand, the projection 4 on the rod 3 acts on the lever 5 so as to pivot the latter clockwise about shaft 6 for releasing the latch member 7 from engagement with the projection 9 on the gear 8.

In this way, the gear 8 is set in rotation through the intermediary of a spring, not shown, and the rotation of the gear 8 is transmitted via counter gear 10 and pinion 11 to the front shutter diaphragm, not shown, so as to release the latter for exposure, as will be realized from FIG. 3. After the lapse of a certain time interval corresponding to the desired duration of the exposure time, release button 1 is released so that the lever 39 is returned by spring 42 to the position shown in FIG. 1.

Thus, the driven lever 34 is lifted by the helical spring 35, and the pressure exerted by the leaf spring 43 on the metallic plate 17 is now relaxed. Thus, the latch member 14 is turned counterclockwise under the force of the spring 16 so as to be moved away from contact with the projection 13 on the gear 12. The gear 12 is now free to rotate and rear shutter diaphragm is actuated under the action of a spring, not shown, so as to interrupt the light passage to the film.

When the shutter dial 19 is moved to one of second position other than the abovementioned first or bulb exposure position B, corresponding to the desired shutter speed, then the disc 26' is brought to the position wherein the contactor 26 thereof contacts with the semicircular terminal segment 27 connecting to the current source 23, and contactor 22 on the shutter dial 19 contacts the resistance, e.g., R.sub.x corresponding to the shutter speed as selected. On the other hand, cam 30 is also turned simultaneously with the shutter dial 19 and the disengaging lever 31 urged under the force of spring 32 as far as the stopper 33. Thus, the inclined foremost part of the plate 44 as shown in FIG. 4, and the link lever 34 is urged to rotate clockwise as shown in FIG. 5 with the shaft 36 as its center, thereby the driving lever 39 being now released from the engagement with the groove 38 on the driven lever 34, i.e., the lever 34 is moved away from the path of the lever 39. When the release button 1 is now depressed manually for shutter actuation, the front shutter diaphragm is set into actuation in the same way as already described in the case of the bulb exposure operation, but the pivotal movement of the lever 39 is not transmitted to the lever 34, and the leaf spring 43 is thus kept from physical contact with the metallic plate 17. Therefore, the release of the latch member 14 from engagement with the projection 13 on the gear 12 is carried into effect upon energization of the electromagnet 18 and the resulting attraction of the metallic plate 17 to the latter, so as to actuate the rear shutter diaphragm after a certain time interval as set by the time delay circuit 24 of the electric exposure mechanism.

According to the present invention, the front shutter diaphragm release mechanism as well as the bulb exposure control mechanism is associated with the rod 3 connected to the manually operable release button 1. The electric exposure mechanism is operative in the case of the normal exposure operation for releasing the latch member 14 operatively connected with the rear shutter diaphragm and setting the latter into actuation after the lapse of a certain time interval as determined by the time constant of the time-delay circuit 24 of the electric exposure mechanism. On the other hand, in the case of the bulb exposure operation, the electric control mechanism adapted for the actuation of the rear shutter diaphragm is disengaged from the rod associated with the release button, and the latch member 14 is mechanically depressed towards the electromagnet 19 by the medium of the driven lever 34 as long as the release button 1 is depressed manually for retarding the rear shutter diaphragm from its actuation. Thus, the electromagnet 18 remains deenergized during the bulb exposure operation, so that the consumption of current may be reduced and the battery may be used for a longer period of time. In the case of the electric exposure operation, viz., when the shutter dial 19 is moved to a position other than bulb exposure position B, the electric exposure mechanism comes into play automatically for more positive and reliable exposure operation.

Claims

What is claimed is:

1. In a photographic apparatus, a combination comprising a focal plane shutter comprising front shutter curtain release means and rear shutter curtain release means; a release device movable between a starting position and an operative position and arranged to actuate said front shutter curtain release means in response to movement to said operative position so that the shutter admits scene light; selector means actuatable to set the shutter for bulb exposure operation and for operation with a preselected exposure time, including a changeover member movable between a first position and at least one second position; an electric circuit including electromagnet means deenergized with a predetermined delay following the movement of said release means to said operative position in said second position of said changeover member, said electromagnet means comprising an armature movable from a first to a second position in response to deenergization of said electromagnet means to thereby actuate said rear shutter release means so that the shutter terminates the admission of scene light; and actuating means for moving said armature to said second position in response to movement of said changeover member to said first position and for moving said armature to said second position in response to movement of said release device to said starting position in said first position of said changeover member so that said armature actuates said rear shutter release means without any change in the condition of said electromagnet means.

2. A combination as defined in claim 1, wherein said actuating means comprises a driving member movable along a predetermined path in response to movement of said release device to said starting position and a driven member which includes motion receiving first and second portions and a motion transmitting third portion, said first portion being located in the path of movement of said changeover member to move said second portion into the path of movement of said driving member in response to movement of said changeover member to said first position whereby said second portion is displaced by said driving member and moves said armature to said second position by way of said third position is response to movement of said release device to said starting position.

3. A combination as defined in claim 2, wherein said driven member is pivotable by said changeover member about a predetermined axis and is movable transversely of said axis by said driving member.

4. A combination as defined in claim 2, wherein said third portion of said driven member is a spring and said driving member is pivotable in response to movement of said release device.