DE1622167C3 - Release device for a cinematographic or photographic camera - Google Patents

Description

The invention relates to a release device for a cinematographic or photographic camera with an electric motor to drive the camera gear as well as a switch arranged in the circuit of the electric motor and a locking device for the correct stopping of the transmission, the armature of an electromagnetic Switching element provided for actuating the switch for the electric motor and the locking device is.

In previously known release devices for cinematographic cameras, a camera release is actuated a switch for switching on and off an electric motor for the film drive and a mechanical one Device, which in the circulation path of a gear element to its position true Determination can be introduced. In many cases, when the camera is switched off, a lever swivels against a stop the Uinia fade and thus prevents further movement of the transmission. To avoid harmful repercussions on the drive motor, its Pinion connected to the shaft via a slip clutch.

However, such a release device has to

Disadvantage that the position of the shutter release on the camera is locally bound and the mechanical transmission elements, like levers and rods, take up a considerable amount of space. Besides, they condition an additional technical and financial effort. Also the one between the pinion and the shaft The slip clutch located in the motor requires a space requirement, the smallest possible constructions prevented.

Furthermore, a switching device for motion picture projectors is known in which a motor via a Belt coupling is connected to a control disc. This control disk works with an angle lever together, which is deflected by a control cam of the disc and by the armature lever a magnet can be fixed. In the fixed position of the angle lever, an approach runs Control disk against the angle lever.

The disadvantage of the known device is that the motor is connected to the transmission via a slip clutch acting belt drive is connected. The gearbox is also non-resilient Lockable lever. Furthermore, it is disadvantageous that a current flows through the electromagnet that is greater than or equal to the response current.

In a further known device, a drive motor in the circuit is a controllable one Rectifier containing control circuit arranged. The controllable rectifier is via a coupling capacitor controlled. A positionally accurate shutdown of the motor of the known device is not easily possible.

In addition, a stop device for the transmission of a cinematographic camera is known in which only breaks the contact of the motor circuit at the moment the transmission is stopped will. For this purpose, a stop lever is provided, which is primarily used to clamp a Wrap spring and to open the motor contact and, secondly, to stop the gearbox serves. The spreading of the wrap spring decouples the gear unit from the motor shaft causes. A true-to-position shutdown is not possible with the aid of the known device possible, as is required for cinematographic cameras.

It is therefore the aim of the invention to create a release device of the type mentioned above, in which the correct position of the motor or the motor gearbox with minimal space requirements of the involved and interacting electrical and mechanical parts should take place without that a clutch is necessary here. To achieve a minimum space requirement for those involved Elements should also keep the power consumption of the release device to a minimum.

According to the invention, the object is achieved in that the movable armature of the switching element carries a lever, on the side facing the gearbox, a rotatable extension that can be introduced into its path and is under the action of a spring is provided so that the current flows through the electromagnetic switching element can be controlled in a manner known per se after it has been switched on by the surge of a previously charged capacitor through at least one resistor to a current value above or below the holding current value and that a resistor can be connected in parallel to the electric motor after the supply voltage has been switched off.
Without the provision of a coupling, the

Lung-true shutdown of the motor transmission is made possible by the fact that part of the kinetic energy of the The transmission and the motor are destroyed in the form of electromagnetic braking energy. Thus becomes by initially opening the motor contact and then bypassing the The resistance of the motor initially destroys part of the kinetic energy by electrical means, after which the remaining part of the kinetic energy through the resilient approach to mechanical Ways will be destroyed. The transmission is thus stopped resiliently, the approach being resilient is pivoted to then return to the rest position under the action of its spring. Therewith a resilient, true-to-position shutdown of the gear unit is guaranteed.

It is known in a cinematographic camera, the current flow through the electromagnetic Switching element after it has been switched on by the rush current of a precharged capacitor to excite the ineffective resistor only until the capacitor has discharged accordingly. Such a known camera does not have a space-saving and low power consumption, one tripping device enabling accurate stopping.

The lever is advantageously designed with two legs, one leg of which the approach and the other second leg has a switch for the electric motor actuating approach. Appropriate the approach is designed as a sword-shaped nose, on the rear end of which a spring acts. In advantageously, the approach falls after switching off the by the coil of the electromagnet flowing stream into a circulation cap.

In an embodiment of the invention, the switch for the electric motor consists of a switch contact set.

In a further embodiment of the invention, the capacitor is arranged parallel to the electromagnet, these two components by means of a mode switch via at least one resistor can be connected to the battery.

The resistor or two in parallel can be advantageously used by means of the operating mode switch Resistors are optionally connected upstream of the electromagnet and the capacitor, with Upstream connection of the two parallel resistors after the discharge surge through the The current flowing through the electromagnet is at least equal to its holding current u.id whereby when connected upstream of one resistor the current flowing through the electromagnet after the discharge current surge is smaller than its holding current.

The capacitor is expediently connected to the by means of a switch operated by a camera shutter release Electromagnet can be connected. This arrangement is advantageous when a remote release is connected off as the motor current does not flow through the remote release cable.

According to another embodiment of the invention, the electromagnet is connected to the electrode of an electrical one Amplifier element, preferably a transistor, connected. The Filektro-

magnet in the collector circuit of the transistor and the capacitor is used to generate the response current Can be connected between base and emitter by means of a switch operated by the camera shutter release. This arrangement is particularly advantageous for connecting a remote release, since the Capacitor is relatively small and its discharge current is correspondingly low. There too Motor current does not flow through the remote release cable, this can be proportionate in its cross-section weakly dimensioned and adapted in its length to all practical requirements. Besides that the previously common use of additional batteries is no longer necessary.

To operate for single image switching or scrolling, the operating mode switch is used to either a resistor or two parallel resistors can be connected between the base and emitter of the transistor, where these resistors together with another resistor form a voltage divider, the base of the transistor is connected to its tap and when one resistor is switched on, the Base potential is dimensioned so that the collector current flowing through the electromagnet is at least whose holding current corresponds and when the two resistors arranged in parallel are switched on, the Collector current flowing through the electromagnet is smaller than its holding current.

The invention is explained in more detail with reference to drawings. Here shows

1 shows the electromagnetic switching element according to the invention,

F i g. 2 the triggering device according to the invention on the basis of a switching example and

F i g. 3 the triggering device according to the invention on the basis of a further switching example.

In the illustration according to FIG. 1, an electromagnet 1 is constructed from a coil 2 with leads 3, 4, a core 5, a movable armature 6 and a yoke 7. A lever 10 formed from legs 10a and 10b is fastened to the movable armature 6 by means of two screws 8 and 9. The lever 10 is rotatably mounted about a bearing pin 11. At the upper end of the leg 10b there is a bearing pin 12 on which a sword-shaped nose 13 is mounted. A leaf spring 14 acts on the rear end of the nose 13 and is fastened to the leg Wb by means of two rivets 15 and 16. The nose 13 carries two stops 17 and 18 which cooperate with the upper end of the leg 10 b . On a shaft 19 there is a rotating screen 20 into which the nose 13 has collapsed in the position shown.

A switching nose 21, which interacts with the center contact 22 a of a changeover switch 22, is attached to the leg 10 a. The changeover switch 22 has two individual contacts 22 b and 22 c, which interact with the movable central contact 22 a.

If the coil 2 of the electromagnet 1 is energized, the angle lever 10 rotates in the direction of arrow A. By means of the extension 21 located on the leg 10 a, the contact 22 a is brought into contact with the fixed contact 22 c, whereby the drive motor of the camera is switched on. At the same time, the nose 13 is removed from the area of the rotating diaphragm 20 located on the shaft 19! and the camera gear released. If the current flowing through the coil 2 is switched off again, the contact set 22α, 22 c again is opened and the motor circuit is interrupted. At the same time, the nose 13 is guided against the rotating diaphragm 20 rotating in the direction of arrow B and is moved downward by the latter about its bearing pin 12. This rotary movement is limited by the projection 18 located on the nose 13. With the further movement of the rotating screen 20, a recess (not shown in more detail) reaches the area of the nose 13. This now falls into the recess and thus prevents further rotary movement of the rotating screen 20 and thus the gear. Under the action of the leaf spring 14, the nose 13 moves back into its rest position after completion of this process.

FIG. 2 shows an example of a circuit for operating the arrangement according to FIG. 1. The circuit has a battery 25 which can be connected by means of a mode switch 26. The mode switch 26 has two movable contacts 26 a and 26 b. The movable contact 26 a cooperates with fixed contacts 26 c, 26 d, 26 e , while the movable contact 260 cooperates with fixed contacts 26 /, 26g, 26 h .

An electric motor 52 for the camera drive is located on the movable contact 22 a of the switch 22 and can either be connected to the battery 25 via the fixed contact 22 c via a switching point 27 or connected to one end of a resistor 28 via the fixed contact 22 b. The circuit also has a capacitor 29, which can be connected in parallel to the electromagnet 1 via a switch 30. Capacitor 29 and electromagnet 1 can be connected to one pole of battery 25 via a resistor 31 and a further resistor 32 that can be connected in parallel to it. Another switch 33 can be connected in parallel to switch 30. In the illustration according to FIG. 2, the operating mode switch 26 is in the "Off" position. In the "continuous run" position, the movable contact 26 a is guided against the fixed contact 26 d. This applies the circuit to the battery 25. At the same time, however, Qe also moves the movable contact 26 b against the fixed contact 26 g, so that the capacitor is now charged via the two resistors 31 and 32 connected in parallel.

When the camera release is actuated, the switch 30 is closed and the electromagnet 1 is connected in parallel to the charged capacitor 29. About the electromagnet 1, its structure and function on hand F i g. 1 was explained above, the discharge current of the capacitor 29 now flows. The electromagnet 1 thereby responds and moves into its working position. The nose 13 is lifted out of the rotating screen 20, while at the same time the movable contact 22 a of the switch 22 is placed against the fixed contact 22 c. ^ß o The drive motor 52 is now energized and operates the transmission and the film transport of the film camera. The current flowing through the two resistors 31 and 32 through the electromagnet 1 is dimensioned in such a way that it corresponds to its holding current, that is to say the camera drive is operated for the duration of the depression of the camera release. When the camera release is released, the switch 30 is opened again and thus the electromagnet 1

currentless. In turn, the nose 13 locks on the rotating shutter 20, the bit further running under the action of inherent in the motor inertia forces gear while the switch b out of the moving-Iiche contact 22a 22 against the fixed contact 22 and the drive motor of the resistor switched 52 28 parallel . As a result, the kinetic energy of the drive motor 52, which acts as a generator after switching off, is destroyed in the resistor 28, so that it is possible to dispense with the use of the previously customary slip clutch between the pinion and the shaft.

To trigger the camera by means of a remote control, the is parallel to switch 30 in one Remote release cable built-in switch 33 operated. The motor current no longer flows as it did before known arrangements about the remote release cable, which is especially not quite new batteries.

To switch to "single image", the movable contact 26 b is guided against the fixed contact 26 / on the operating mode switch 26, so that now only the resistor 31 is connected to the capacitor 29 and electromagnet 1. The current flowing through resistor 31 and electromagnet 1 after the capacitor has been charged is dimensioned so that it is smaller than its holding current. The electric motor 52 is thus immediately disconnected from the battery 25 again after the capacitor has been discharged and switched on to the resistor 28, while the camera gear is blocked by the nose 13 falling into the rotating diaphragm. Each time the switch 30 or 33 is actuated, the camera's film transport is only switched on for a brief moment, so that the film is only advanced by one frame.

Fig. 3 shows a further circuit variant for actuating the triggering device. The electromagnet 1 is now in the collector line of a transistor 36, in the base-emitter path of which the resistor 37 is located, to which a resistor 38 can be connected. The connection takes place via a mode switch 39, which has two movable contacts 39a and 39 ft and fixed contacts 39 c, 39 d and 39 e or 39 /, 39 # and 39Λ. A capacitor 41 of the base-emitter path of the transistor 36 can be switched on via a switch 40. A switch 42 can be arranged parallel to switch 40 for remote triggering.

A resistor 43 acts as a working resistance for a stabilizing element 44, e.g. B. for stabilization the voltage supplied by a battery 45. By means of the switch 40 is the resistors 37 and 38 a further resistor 46 for forming a voltage divider can be switched on. A light sensitive Receiver 47 forms together with a measuring mechanism 48, a resistor 49 and a by means of a switch 50 z. B. for consideration different film sensitivities connectable further resistor 51 the exposure measuring device. The drive motor 52 is again as in FIG. 2 by means of that actuated by the electromagnet 1 Changeover switch 22 can be connected either to the battery 45 or to the parallel resistor 28.

If the movable contacts 39 ″ and 39 b of the operating mode switch 39 are placed on the fixed contacts 39 d or 39 #, the operating mode switch 39 is in the position for “continuous operation”. The capacitor 41 is charged via the resistor 46 to the stabilized voltage applied to the stabilizing element 44. If the switch 40 is closed by means of the camera release, the capacitor 41 discharges via the resistor 37 and the base-emitter section of the transistor 36. This current surge generated in the emitter section of the transistor 36 is amplified in the ratio of the current amplification factor of the transistor 36 so that the collector current flowing through the electromagnet corresponds to its response current. As a result, the drive motor 52 is energized again by switching the movable center contact α of the switch 22 to the fixed contact 22 b. After the capacitor 41 is discharged, a potential is created at the base of the transistor 36, the level of which corresponds to the ratio of the resistors 37 and 46 forming a voltage divider. This potential is dimensioned such that the collector current flowing through the electromagnet I corresponds at least to its holding current, the film drive is thus operated for the duration of the closing of the switch 40. Only when the camera release is released is the switch 40 opened again, so that transistor 36 now blocks, the electromagnet 1 drops out again and the film run is thus ended. The switch 40 can again be bridged by means of a remote release 42.

When the mode switch 39 is in the “single image” position, the movable contact 39 a is on the fixed contact 39 c and the movable contact 39 ft on the fixed contact 39 /. This is what happens in the base-emitter path of the transistor 36 arranged resistor 37, the resistor 38 connected in parallel. If the charged capacitor 41 is connected to the base-emitter path of the transistor 36 by means of the switch 40, its discharge current now flows via the two parallel resistors 37 and 38 and via the base and emitter of the transistor 36, the collector current thus generated being sufficient to trigger the electromagnet 1 to leave and to bring into his working position.

But since the connection of the resistor 38 increases the potential at the base of the transistor 36 because of the changed voltage divider ratio has decreased, the collector current flowing through the electromagnet I is smaller than that Holding current. Immediately after the capacitor has been discharged, the electromagnet 1 drops out again and lays down The camera gear is fixed in position via the nose 13 and the rotating screen 20. Simultaneously the movable contact 22a is fed to the fixed contact 22 ft and thus the electric motor 52 is switched off and its parallel resistor 28 switched on. Each time the switch 40 is actuated, the camera gear only advances the film one frame at a time.

For this purpose 2 sheets of drawings

709 632/355

Claims (11)

Patent claims: 1. Release device for a cinomatographic or photographic camera with an electric motor to drive the camera gear as well as a arranged in the circuit of the electric motor switch and a locking device for accurate position Shutdown of the transmission, the armature of an electromagnetic switching element for Actuation of the switch for the electric motor and the locking device is provided, characterized in that the movable Armature (6) of the switching element (1) carries a lever (10) on which the gear is facing Side one that can be brought into the path of the same, rotatable and trained under the effect a spring (14) standing approach (13) is provided that the current flow through the electromagnetic Switching element (1) in a manner known per se after it has been switched on by the surge of a previously charged capacitor (29 or 41) through at least one resistor (31 or 32, 37 or 38) to one above or below the holding current value located current value is controllable and that after When the supply voltage is switched off, a resistor (28) can be connected in parallel to the electric motor (52) is. 2. Trip device according to claim 1, characterized in that the lever (10) has two legs is formed, whose one leg (£ 10>) the approach (13) and the second leg (10α) a switch (22) for the electric motor (52) has actuating approach (21). 3. Trip device according to claim 2, characterized in that the projection (13) as sword-shaped nose is formed, on the rear end of the spring (14) acts. 4. tripping device according to claim 1 or 2, characterized in that the projection (13) according to switching off the current flowing through the coil (2) of the electromagnet (1) into a Revolving fastener (20) is incident. 5. Tripping device according to one of the preceding claims, characterized in that the switch (22) for the electric motor (52) consists of a switching contact set (22 a, 22 b, 22 c) . 6. Tripping device according to one of the preceding claims, characterized in that that the capacitor (29) is arranged parallel to the electromagnet (1) and these two Components by means of a mode switch (26) via at least one resistor (31,32) to the Battery (25) can be switched on. 7. Tripping device according to one of the preceding claims, characterized in that that the resistor (31) or two parallel resistors (31, 32) by means of the mode switch (26) can be optionally connected upstream of the electromagnet (1) and your capacitor (29) are, with the upstream connection of the two parallel resistors (31, 32) of after your discharge surge through the electromagnet (1) the current flowing at least corresponds to its holding current and with an upstream connection of one resistor (31) which after the discharge current surge through the electromagnet (1) flowing current is smaller than its holding current. 8. Tripping device according to one of the preceding claims, characterized in that that the capacitor (29) by means of a switch (30) operated by a camera shutter to the Electromagnet (1) can be connected. 9. Tripping device according to one of the preceding claims, characterized in that that the electromagnet (1) to the electrode of an electrical amplifier element, preferably a transistor (36) is connected. K). Release device according to one of the preceding claims, characterized in that that the electromagnet (I) is in the collector circuit of the transistor (36) and the capacitor (41) by means of a switch (40) operated by the camera release between base and emitter is connectable. 11. Tripping device according to one of the preceding claims, characterized in that the resistor (37) or the two parallel resistors (37, 38) can be switched on by means of the (~ g mode switch optionally between the base and emitter of the transistor (36), that these Resistors (37, 38) together with another resistor (46) form a voltage divider, at the tap of which the base of the transistor (36) is connected and when one resistor (37) is switched on, the base potential is dimensioned so that the voltage generated by the electromagnet ( 1) the collector current flowing at least corresponds to its holding current and when the two parallel resistors (37, 38) are switched on, the collector current flowing through the electromagnet is less than its holding current.