CH433003A - Method for controlling the device for advancing the film step by step of a cinematographic projection apparatus and apparatus for carrying out this method - Google Patents

Description

Method for controlling the step-by-step advancement of the film of a cinematographic projection apparatus and apparatus for carrying out this method

The subject of the present invention is a method <B>for</B> controlling the step-by-step film advance device of a cinematographic projection apparatus by electromagnetic coupling of the said step-by-step film advance device. film with 1st projection mechanism.

Such a process can be used advantageously for the projection of cinematographic documents of a typical type and more particularly of films intended for a scientific or medical purpose, or even of films intended for teaching, professional films, etc.

The method according to the invention has the purpose of making it possible to obtain, starting from Standard or higher projection rates (for example sofft 48, 24 or 16 images/second), any lower projection rate in images/second, until stop Image.

The method according to the invention is characterized in that this electromagnetic coupling is controlled by the coincidence of a triggering pulse forming part of a series of triggering pulses generated in synchronism with the shutter of the projection apparatus and of a Secondary impulse or pulse forming part of a series of secondary impulses whose frequency can be modified fi. will, this coincidence being achieved by placing the secondary impulse in the memory until the arrival of the triggering impulse, the projection mechanism rotating at a constant speed which corresponds to 1a. highest frame rate.

The process according to the invention has the advantage of making it possible to change the speed and the direction of film travel by acting solely on the aforementioned secondary pulses, that is to say without modifying the speed and the direction of rotation of the film. engine.

The invention also relates to a cinematographic projection apparatus for the implementation

of the präcite, characterized in that it comprises a generator of pulses of determined frequency; a positive device for transforming these pulses into continuous signals and for synchronizing said pulses and said signals, at least one amplifier excited by said signals and supplying one or more Gearo-magnets cooperating with the stepping advance device film, and a constant speed motor for rotating the projection mechanism.

In the appendix dessms given only at ä. By way of example FIG. 1 represents the diagram of a circuit for Z'entramement and the commmaande of a projection apparatus, 1adite command can also be programmed m6e.

fig. 2 is a schematic representation of the assembly of the rotary member which generates the Pulses.

fig. <B>3</B> shows the assembly of a pulse counter operating as a frequency divider.

fig. 4 represents the pulses ä, the input of the counter prkite and the various forms of signals obtained from the ius, the, output of said counter.

fig. 5 represents the recording of the control signals of the amplifiers supplying the electromagnetic devices triggering the advance of the film.

fig. 6 shows schematically an assembly making it possible to establish the programming of the projection device from the shooting camera.

fig. 7 shows schematically and in perspec tive a projection apparatus solon 1'invention; fig. 8 show in parspectve a detail of the apparatus of 1a. sig. 7.

<I>Electronic control</I> According to the embodiment shown in figs. 1 and 2, the .eommamde system essentially comprises

a shutter 1, said auxiliary shutter of synchroni zation, fitted with a radial ferste 2 and mounted on the axis 3 of the cinematographic shutter 4 of the conventional type. Thanks to this method of assembly, the two shutters are rigorously synchronized.

On either side of the auxiliary shutter 1 are placed photodiodes 5a, 5b, 5c and 5d, and tolles quo light sources 6a and 6b each facing a photodiode. When the auxiliary shutter 1 rotates, at each passage of the ferste 2 in front of one of the photo-diodes 5a, 5b, 5c or 5d, said photo-diode is 6eIairee by the corresponding light source and consequently, a Pulse the duration is proportional to the width of the edge and to the speed of rotation of the auxiliary shutter. and adopts the amplitude is a function of the quantity of light received by the photo-diode. These pulses can be suitably amplified and shaped if necessary by any device of known type (not shown).

The pulses generated by the photo-diode 5a are sent to a first stage of a counter 7 composed (see FIG. 3) of a circuit comprising several flip-flops or flip-flops A, B, C, D, of known type, my heads are in cascade, that is to say that the output 8 of each stage constitutes the entrance to the following stage. Leg two tubes or transistors a1 a2, b1 b2, cl c2, dl d2 ... of each floor are mounted tolle So that when powered up, one of said transistors or analogs of a 6iage is conductive and the other blocked. Arranging a Pulse of the proper direction at the input of a Stage reverses the balance and the first transistor or the like is off while the second becomes conductive. .

If we assume that in the initial state the signal which is present at the output 8 of the stage A- is transmitted by the second transistor a2 of said stage, the pulse coming from the photo-diode 5a switch the corresponding stage and delete this Signal. Only the second Pulse coming from the photo-diode 5a causes a new change of status and reproduces <B>the</B> Initial signal at the considered output of the stage A. The First Stage A of the counter 7 having the effect to divide by two the number of pulses which reach it from the photo-diode 5a, year a, at the exit of the floor. A, a Signal During the lapse of time separating two Pulses and an absence of signal During the following interval. Each Stage A, B, C, D being connected to the next by a capacitor 9 which transforms <B>the</B> permanent Signal into a Pulse an a, at the output of the second Stage B, a Signal and, at I at the entrance to the third stage C, a Pulse each time <B>the</B> photo-diode 5a sends four Pulses.

Ort has represented in fig: 4 the input vnpulsilons of the counter 7 as well as the signals at the output of each of the 6iages of said counter. The arrows shown on the said signals represent the pulse edges which trigger the next stage.

To compensate for the excessively rapid increase in the divisor, which increases according to a geometric progression of rann two according to the number of stages, an receives <B>la</B> trän sistor b2 from stage B, for example, to transistor a2 of 1'6tage A, with the aid of a suitable circuit, provided with a switch 10 so as to return, when said switch 10 is closed, an additional pulse to the transistor a2, Pulse which switches the P6tage A

before the arrival of the pulse coming from the photo-diode 5a and consequently makes it possible to obtain or eliminate, at the output of stage B, a signal or an absence of signal every three pulses of the photo-diode 5a. diode 5a.

The outputs of the different stages are connected to a speed selector 11, constituted by a switch or by a step relay, which allows, by choosing the output of the appropriate stage and by opening the switch 10 or a switches 10 with the aid of a remote control unit 12a to obtain, at the output of said speed selector 11, a determined frequency of pulses per second. A switch 12b that can be operated by hand and also connected to the selector makes it possible to obtain the Freeze Frame.

Ort will first consider the action of the photodiodes 5a and 5b, the action of the photodiodes 5c and 5d being explained below.

The photo-diode 5b is located so that the ferste 2 of the auxiliary shutter 1, integral with the cinematographic shutter 4, reaches this photo-diode a short time before the pulse 4a of the cinematographic shutter does not passes in front of the optical axis - conventionally represented by the Line segment O shown in phantom. It is at this moment that it is advisable to act on the claw-parting organs or on the barb-carrying organs forming part of the film advance mechanism so that the claws or the barbs are introduced into the perforations prA -views in the film.

The photo-diode 5a which is also used, as has been seen previously, to supply the input of the counter 7, which is dead as a frequency divider, with pulses in synchronism with the rotation of the auxiliary shutter 1, finds itself angularly displaced with respect to the photo-diode 5b by a quantity such as it is at the place of the cycle where the end of the action must take place. of an Image. This photo-diode 5a is placed so that it receives a luminous flash and therefore generates an electric pulse before the pulse of the cinematographic shutter 4 has left the optical axis O. This makes it possible to take into account the time necessary for the release of the claws. or pins of the film drive mechanism out of the perforations.

It can be seen that the photo-diode 5b determines the precise instant at which the actuation of the claw-carrying or barb-carrier members must take place so that they engage the perforations of the film before an image advance so that said barbs or said claws cause the movie. This photo-diode 5b therefore constitutes the start-of-action photo-diode. On the other hand, the photo-diode 5a determines the precise instant oh, the advance of the film having instead, it is advisable to release the claws or the pins from the perforations of the film so that the action of the mechanism of the film ceases. 'coaching. This photo-diode 5a therefore constitutes the end-of-action photo-diode.

Thus a pulse coming from the speed selector 11 and whose frequency is merged by the counter 7 is brought, via a capacitor 13, to the input of a flip-flop or flip-flop 14 adopts the state of which free is reversed and which sends a Signal to one of the inputs 15a of an <B>e ET</B> port 15.

Each time auxiliary shutter 1 is rotated, photodiode 5b sends a Synchronization Pulse to the other input 15b of Bridge 15 and this Pulse

is transmitted to the output 15c of said station quo if the flip-flop 14 has established a signal at its between 15a. Thus the pulse transmitted to the output 15c of the station 15 is synchronized at the frequency imposed by the counter 7 and this at a precise moment in the cycle of the mechanism, sofft in 1'ocurrenee at the moment when it is appropriate to act. nur the perforations to trigger the advance of the film by an amount corresponding to an Image.

It should be noted that the role of the basoule 14 is that of a memory which stores the information coming from the counter 7 until the arrival of the synchronization signal coming from the photo-diode 5b.

Output 15c of station 15 therefore conducts the synchronization pulse coming from photo-diode 5b, when at least counter 7 allows it, to the input of a flip-flop 16 which in turn inverts and sends a signal to one of the amplifiers 17a or 17b which feeds the coil 18 of the action electromagnet on the Forga ne bearing the claws or the member bearing the pins which engage the perforations in the film.

The amplifier 17a, called the re-entry amplifier, supplies the first coil 18a of the leotro-magnet 18, called the re-entry or end-of-action coil, the coil which, in the first flush of a claw device for example, controls the retraction of the claws, that is to say their release from the perforations of the film. The amplifier 17b, called the output amplifier, supplies the winding 18b of the electromagnet 18, called the output or action coil, the winding which controls the output of the claws, that is to say their engagement in the perforations. of the movie.

Simultaneously with the supply of the output amplifier 17b, the flip-flop 16 transmits, via a capacitor 19, a pulse to the flip-flop 14 whose balance is reversed, suppressing the counter signal previously transmitted to station 15 which now blocks all the synchronization pulses which could occur before a new pulse from counter 7 decides on a new image advance.

The signal transmitted to amplifier 17b by flip-flop 16 remains unaltered, the balance of said flip-flop remaining unchanged. But the slot 2 of the auxiliary shutter 1 passing in front of the photo-diode 5a. rette last sends a pulse to the flip-flop 16 whose Mtat is reversed. Flip-flop 16 then suppresses the signal to output amplifier 17b and instead establishes a signal to input or end amplifier 17a which controls the engagement of the claws out of the perforations after the advance of an Image. .

The operating cycle is entirely automatic and controlled by the auxiliary shutter 1 rotating at constant speed. It is obvious that a variation in the speed of this shutter and therefore of the mechanism to which it is synchronized would only have the consequence of modifying the calibration of the projection rate in absolute value, that is to say of distorting the rhythm in Images per second without disturbing the operation of the projector. It is therefore possible, by providing several speeds of rotation of the shutter 1, to multiply the number of speed combinations provided on the counter.

The photo-diodes 5d and 5c which are diametrically opposed to the photo-diodes 5b and 5a respectively and are therefore out of phase by a half-period with respect to the latter, are provided for the control

film drive mechanism when the projector is operating in reverse. The photo-diodes 5d and 5c in fact send pulses which are exactly opposite, during the same cycle of the auxiliary shutter 1, to the control pulses sent by the photo-diodes 5a and 5.b. 0n selectively sends the pulses generated by the photo-diodes 5a, 5b or by the photo-diodes 5d and 5c to the counter 7 and to the post 15 as well as to the flip-flop 16 thanks to inverters 20 aetionn6s by a relay 21 powered by an amplifier 22, controlled by a flip-flop 23 itself controlled by a reversing switch 24 operable by hand.

In the absence of an action from the electromagnet 18 controlling their exit, the claws constantly execute a vertical to-and-fro movement, marking, at the high point and at the low point, a stop corresponding to a rotation of 1000 of the drive cam of the frame for example, or of Xo depending on the first type of cam.

The raising and lowering movements of the claw are carried out at different and symmetrical instants of the same cycle, that is to say for a single and determined direction of rotation of the auxiliary synchronization shutter, the movement descent a er when the blade 4a of the shutter 4 masks Optical Faxe O and the first movement of ascent when the blade 4b of this shutter has, replaced the blade 4a. The moments corresponding to ä. each of these actions are therefore exactly opposed during the same cycle. This is for this reason that the two photo-diodes Sc and 5d, intended for the reverse gear control, are arranged diametrically to the photo-diodes 5a and 5b respectively.

We can see that if the claw exit command occurs at the bottom point of the vertical travel, the claw, twisted as it rises, drives the film and causes it to advance by one image towards the top. On the contrary, if the claw exit takes place at the high point, the claw drives the film during its downward movement.

Thus the projection device described allows the image to be stopped, the direction of scrolling to be reversed or the projection rate to be modified without modification of the movements and the speed of the mechanism (for example without stopping or modification of the speed, nor reversal of the direction of rotation of the motor for mechanisms produced from a rotary movement).

We obtain a minimum of üertie in res command of the stops, of inversion of the direction of movement or of modification of cadence thanks to the fact that Fon moves only the mechanism of action on the perforations themselves, mechanism which Fon can construct as lightly as possible. quo possible, in order to reduce the inertia of the masses to be moved.

<I>Programming device</I> One of the advantages of the electronic control is to allow 1a. programming and complete automation of the projection of a cinematographic document using a storage of pulses and control signals thanks to a tape recorder for example.

fig. 1 shows a mode of malination of a device for carrying out a tolle stored in memory.

This device comprises two oscillators 70 and 71 tuned to two different frequencies, for example 6

<U>KH-</U> and 8 KHz respectively, connected on the one hand to an input circuit of a tape recorder 72, for example to the microphone socket 73 of said tape recorder, and on the other hand, to the output of the output amplifier 17b via an inverter 74 actuated by the relay 21. This device further comprises two detectors 75 and 76 set to the same frequency as the oscillators 70 and 71 prkit6s i.e. ie 6 and 8 KIHz respectively. The inputs of these detectors are connected to the output socket 77 of the tape recorder 72 and their outputs are returned from one part to 1a. flip-flop 14 via Biodes or the like 78 and 79 and a capacitor 80 and on the other hand to the basoule 23 via Biodes or the like, 81 and 82.

At the command of a claw output or, more generally, of an action on the perforations, a signal is generated by the output amplifier 17b and this signal is fed, according to the position of the relay 21 and by the intermediary of the inverter 74, to one or the other of the oscillators 70 and 71. The oscillator 71 receives for example this Signal when the Fossilator 70 which responds to this Signal when the relay is in the Reverse Stick Position, ie energized. Either of oscillators 70 and 71 oscillates during 1a. duration of this Signal and emits at its output an alternating Signal whose frequency is specific to it and of an adequate amplitude to be amplified and recorded On the magnetic tape of the tape recorder. The duration of the recorded signal corresponds to the exit time of the claws or the like.

The tape recorder therefore records a signal at each image advance executed by the projector, the signal having different frequencies depending on the stick direction; the absence of any Signal results in a freeze on the image.

Ort can, of course, reverse this recording mode and use the input amplifier to record a continuous signal on the magnetic tape, a signal which is interrupted when the perforations are acted upon.

0n has represented in FIG. 5 the curves G and G' corresponding to the use of the output amplifier and showing the recordings respectively in the back channel and in the front channel. In this same figure, an has drawn the curves H and H' corresponding to the use of the reentrant amplifier and showing the recordings in the back neck and front neck respectively.

The tape recorder and the projector have speeds which theoretically are constant. It is however useless to synchronize these speeds and it is enough that the variations of one or the other do not increase by approximately 5% so that no detectable disturbance occurs.

When the Program is restored, the Tape of the tape recorder and the film having been rewound in their initial positions, the output of the tape recorder being connected to the projector, it suffices to put the in the neck the tape recorder.

At the moment when the First Signal occurs on the Magnetic Band, it is amplified and brought to detectors 75 and 76 tuned to two different frequencies corresponding to those of oscillators 70 and 71, that is to say 6 and 8 <U. >KHz</U>. Depending on the frequency of the Signal, 8 KHz for example, Detector 76 is tuned to this

frequency detects the signal, rectifies it, and shapes it correctly. The Signal is brought to the flip-flop 14, at the input where the pulses of the counter 7 arrive, the circuit is then broken, since the control device is in the Off position. 6dently. The signal coming from the detector 76 is also led to the input 23a of the rocker 23, input which corresponds to the drive of the film in the forward sleeve. The Signal introduced in flip-flop 14 and coming from the tape recorder, therefore replaces that which would normally come from counter 7. Flip-flop 14 sends a signal to Gate 15, which authorizes the Passing of the Synchronization pulse coming from Photodiode Sb, pulse which acts on basoule 16, which reverses the balance of flip-flop 14 and controls the output amplifier or aotion on perforations 17b. The operation of the projector being automatic Pen dant a complete cycle, year sees that it suffilt to replace 1'pulse coming from the counter 7 by that coming from the tape recorder 72 to complete a film advance.

Of course, when the tape recorder's read head encounters a 6 KHz Signal, it is the detector 75 tuned to this frequency which sends a Signal to flip-flop 14 and determines the known process. But this detector 75 brings a pulse to the input 23b of the a. Rocker 23, input which corresponds to the drive of the film in the rear sleeve. Flip-flop 23 then switches to another balanced state and supplies amplifier 22 which supplies relay coil 21 thus causing, thanks to inverters 20 and 83, the direction of the film to change.

The tape recorder therefore very simply replaces the counter to fully program the projection of the cinematographic document, faithfully reproducing all the changes of rhythm, the freeze frames and the inversions of the stick.

If this tape recorder is a model with two simultaneous takes (stereophonic for example), it is then possible to record a commentary or a sound system On the second Track, this recording always remaining synchronized with the projection Program and the Images of the film.

Similarly, by modifying the mabnetophone itself, for example by agreeing to amputate the Soundtrack of higher frequencies, it is possible to record a commentary and a projection Program On the same Track. It suffices for this to use tuned filters which suppress for the loudspeaker the frequencies higher than ten thousand periods for example, and for the control device all the frequencies lower than this frequency.

The programming process described above makes it possible to synchronize the projection image advances at any frequency, even one that is continuously variable, the only condition to be observed being that the frequency to be used is always less than or equal to the projector speed in cycles per second.

If the projection device is running at 48 cycles per second when we can only expect a maximum rate of 24 frames per second from the tape recorder, the result is that we can accept very large speed differences between the tape recorder and projector. A normal cycle Image of the dune projector For 1/24th of a second ie For two cycles of the mechanism. If a slip-

speed change occurs, it is corrected as soon as it reaches the value of 1/48th of a second. This timing correction has the effect of shortening or lengthening a Projector Image cycle by 1/48th of a second. A Stellar correlation is invisible to the projection and makes it possible to maintain, for example, a synchronization between the Images of the film and the sound recorded on a tape recorder.

This automatic synchronization makes it possible to envisage uses different from those which have been described above.

Thus it is possible to use for the synchronization of the projection any Base frequency independent of that of the projection device, provided that this Base frequency is lower than the frequency of the said device which can be used, for example. the frequency of the alternating current distribution network, or a sub-multiple of this frequency, using it to supply the first counter 7 (see fig. 1) instead of the frequency determined by the photo- diodes 5a or 5c and, after division and selection of the output stage of the counter by the selector 11, supplying the flip-flop 14 which resets the image advances in synchronism both with this frequency and with the pulses given by the photo-diodes 5b and 5d.

It should be noted that the storage of the Impulses makes it possible to carry out the com pIate programming of a projection, even if a freeze on the Image, a rewind or a change in the frequency of the scrolling of the Images is operated.

In the example described above, the programming of the projection device is done by the projector itself using the signals from the aetion circuit on the perforations to power the oscillator bones 70 and 71 for reverse gear. and forward. It is thus possible to carry out a post-sounding of a cinematographic document.

But it is also possible to program the projection of a document from the Stage of its creation at the time of its recording Jan 1a. Shooting camera.

0n has represented in fig. 6 schematically, an example of an assembly making it possible to record the program on magnetic tape of the tape recorder 72 (see fig. 1) during the shooting of cinematographic documents.

The camera 101 is provided with a rotary contact 102 mounted on the axis 103 carrying the shutter 104, this contact closing the circuit of a battery 105 or any other current source at each cycle of the mechanism of the camera. This circuit supplies an oscillator 106 oscillating at 8 KHz, that is to say an oscillator analogous to oscillator 71 of FIG. 1, the frequency which corresponds to forward motion. This oscillator supplies a stable frequency to the tape recorder 72 at each exposure of the film, or between successive exposures depending on the recording mode chosen.

To facilitate recording, the start and stop of the tape recorder 72 can be slaved to the release button of the film camera by means of a contact member 107 inserted in the motor supply circuit. of the tape recorder 72.

We see in conclusion that the electronic control of the projection allows not only the post-

programming and the sound system of a cinematographic document using the projector itself but also the faithful programming and sound system of a film from the very moment of its creation with enslavement of the future projection at the speeds of Taking of views from the camera at the time of sound and visual recordings.

These advantages bring to the field of amateur cinema, for example, the possibility of mixing techniques of shooting and sound recording following the sequences of the processed cinematographic documents, adding special effects such as 1a. modification of the rhythms of projection, 1a reverse, stop on Image while ensuring the automation of 1a projection and an uninterrupted synchronized sound system.

0n has represented schematically in fig. 7 a projection device provided with Electronic Synchronization.

We have used to designate those of the elements of these devices which have been mentioned in fig. 1 the same my reference figures as those used in fig. 1. Laxe 3 places the cinematographic shutter 4 whose central part coincides with the synchronization shutter and which is provided with the slot 2. On each side of this shutter are placed the photo-dios of 5a and 5b etc. and lamps 6a, 6b, etc. The film advance mechanism is constituted by a rod 108 articulated, at one of its ends, to a rod 109 integral with the moving coils 18a, 18b (not shown) of the electromagnet 18 for re-entry and exit of the claws. This link is provided, at its other end, with a claw 110 engaging in the perforations 111 of the film 112. The link 108 comprises a frame or the like 113 Jans which engages a cam 114 with square movement mounted on the axis 3 and which determines the first step of the film. The rod 108 pivots in its vertical plane around the axis of articulation with the rod 109 and moves perpendicularly to the plane of the fit under the action of the said rod which slides on itself according to a back-and-forth movement. comes in such a way that the claw engages or not Jans the perforations of the film. 0n @ gives, of course, to the frame 113 Jans which engages 1a cam 114 sufficient dinnensions to allow the translational movement of 1a bielfette.

The aforementioned film advance mechanism further comprises a rod or the like 115 provided, at one of its ends, with a counter claw 116 and articulated, at its other end, at one of the arms 117a with a lever 117 bone blinking around a fixed axis 118, the other arm 117b of which is articulated to the rod 108. We see that the rod 115 and the rod 108 perform at each instant identical movements and in opposite directions so that the counter claw 116 performs in & out movements perpendicular to the film plane.

To prevent the extension or re-entry of the claws outside the high and low points of the vertical stroke of the connecting rod 108, there is provided a bare claw safety or retention device which, for the clarity of the drawing, has been omitted. . 7 and shown separately in fig. B. This safety device consists of two guides 119 Jans which engage two lugs 120 of the linkage, these guides being provided, near their center, with slats 121 which oppose the movement of the lugs 120 Jans in the first direction perpendicular to the plane of the film during the

veriical path of the bielfette 108 but allow this displacement when said bielfette has reached the high point or the first low point.

0n a also represents <B>the</B> supply and retention debtor 57 of the film and its axis 57a. This debtor is immobilized by a brake 61ectro-magndtique 122 alimen t6 by 1'amph .icateur 17a called rentrde claws (see Fig. 1), so outside: any advance of the film. The axle 57a is made integral with the mechanism of the projection device, in a suitable rotation ratio and in a direction of rotation corresponding to the direction of travel of the film, thanks to two gears 123 (dopt one Beul is represented). These gears are made integral with Faxe 57a by means of clutches 124 and 125, one or the other supplied, depending on the position of the inverter relay 21, by the output amplifier 17b (see FIG. 1).

Finally, the film delivery and reception coils are permanently driven in a suitable direction of rotation which tends, for each of them, to roll up the wound. They are driven either by the intermediary of electro-magnetic clutches or by mechanical friction allowing very significant sliding. The well-known devices make it possible to adjust these slips as a function of the tension of the film, that is to say according to <B>the</B> diameter of the film wound on the reel and according to the projection speed.

Many modifications could also be made to the process, to the numerical values indicated and to the devices described.

Thus, for example, the auxiliary synchronization shutter could be replaced by any other device capable of emitting periodic pulses in synchronism with the mechanism of the headlight, for example magnetic sensors, contact sensors, etc. The control device could be made from other electronic elements than those which have been described and shown, such as ring counters for example.

Likewise, the inverter relay 21 could be replaced by electronic switching without inertia controlled by flip-flop 23 on the same basis and according to the same operating principle as that applied to relay 21.

Finally, it should be noted that instead of the cinematographic shutter 4, consisting of two equidistant blades of 90° each, one could also use any other shutter of a known type, for example a ball shutter.

Claims (30)

CLAIMS I. Process for controlling the device for advancing the film step by step of a cinematographic projection apparatus by electromagnetic coupling of the said device for advancing the film step by step, with the projection mechanism, characterized in that this electromagnetic coupling is controlled by the coincidence of a Trigger Pulse forming Part of a series of triggering pulses generated in synchronism with the closure of the projection apparatus and a Secondary or Control Pulse forming Part of a Series of triggering pulses. The secondary pulse adopts the frequency can be modified at will, this coincidence being achieved by storing said secondary pulse until the arrival of the trigger pulse, <B>la</B> projection mechanism rotating at a constant speed which corresponds to the highest frame rate. II. Cinematographic projection apparatus for implementing the method of claim I, characterized in that it comprises a pulse generator of determined frequency, a device for transforming these pulses into continuous signals and for synchronizing said impulses and said signals, at least one amplifier excited by said signals and supplying one or more electromagnets cooperating with the stepper film advance device, and a constant speed motor for the rotational drive of the mechanism of projection. SUB-CLAIMS 1. Pro & d6 according to claim I, characterized in that, over several shutter cycles, a first series of pulses is generated, and a second series of pulses shifted in time with respect to to the Pulses of the First series, an transforms the First series of pulses into: a Series of signals of adjustable duration whose frequency is a sub-multiple of the Base frequency, an transforms the said signals into secondary Pulses of this sub-multiple frequency, an synchronizes said secondary pulses with the pulses of said second series of pulses, and an transforms said secondary pulses into permanent signals which are used alternately to control the electromagnetic action on the stepping device. not from the movie. 2. Process according to sub-claim 1, characterized in that the pulses of the First Series of pulses are used to control the action of the aforementioned permanent signals on the device for advancing the film step by step. 3. Method according to sub-claims 1 and 2, characterized in that the pulses of the first series of pulses are generated at a time prior to the time when the cinematographic shutter discovers the optical axis. 4. Method according to sub-claim 1, characterized in that the pulses of the second series of pulses are generated at a time prior to the time when the cinematographic shutter closes the optical axis. 5. Process according to sub-claim 1, characterized in that the number of images per second is varied by acting on the duration of the aforementioned adjustable-duration signals. 6. Process according to sub-claim 1, characterized in that, when the direction of travel of the film is changed, an additional series of pulses are used which are identical and of the same frequency as the two series. of previous pulses, additional series of pulses being generated and used in the same way as said previous series but being shifted by half a period with respect to the latter. 7. Process according to claim I, characterized in that, in the case of a projection apparatus without a mechanical cinematographic shutter, an uses the pulses generated in synchronism with the shutter to control <B>the</B> frequency of the Flashes delivered by the light source and the synchronism of said flashes with the advance of the film. B. Process according to sub-claim 1, characterized in that each Image of the film is identified by counting and storing pulses whose frequency is a sub-multiple of the aforementioned Base frequency, so as to @on to make it possible to find an Image located during a first projection. 9. Process according to claim I, characterized in that the aforementioned pulses are used for the synchronization of the film with a recording device. 10. Process according to claim 1, characterized in that provision is made for programming a series of operations by storing the aforementioned pulses. 11. Process according to claim 1, characterized in that, for the synchronization of the projection, any Base frequency independent of that of the projection device is used, this Base frequency being lower than the frequency of the said projection device. projection. 12. Method according to sub-claim 11, characterized in that the frequency of the sector or a sub-multiple of this frequency is used as base frequency. 13. Process according to sub-claim 12, characterized in that, for the programming of the projection device, a magnetic tape is used on which said programming was recorded during the filming of the cinematographic documents. 14. Process according to sub-claim 13, characterized in that provision is made for the starting and stopping of the magnetic tape recorder to be controlled by the shutter release button of the camera. . 15. Apparatus according to claim 11, characterized in that the aforesaid pulse generator consists of a rotary shutter with a radial slot and is arranged between a light source and at least two photosensitive members of such type that said photosensitive members are excited with each rotation of said shutter. 16. Apparatus according to sub-claim 15, characterized in that the aforementioned photosensitive members are constituted by photo-diodes associated in pairs, the two photo-diodes, of the same pair being offset angularly by an angle substantially Equal to or slightly greater than the angle of the cinema shutter blades. 17. Apparatus according to claim II and sub-claims 15 and 16, characterized in that the aforementioned transformation device comprises a counter mounted as a frequency divider and powered by one of the aforementioned photo-diodes, called photo-diodes. end of action diode, a station on the input is supplied RTI ID="0007.0273" WI="9" HE="4" LX="835" LY="2309"> on the one hand by said counter, via a first flip-flop, and on the other hand by the photo-diode associated with the aforementioned photo-diode, called the action start photo-diode, said station itself being connected to two amplifiers supplying the or the aforementioned electro-magnets, by means of a second rocker. 18. Apparatus according to sub-claim 17, characterized in that the counter comprises several stages in cascade, at least two successive stages being connected by a conductor connected to a switch, said conductor tewr connecting the first element of the upper stage to the second element 616ment of the lower stage so as to suppress a pulse at the output of said upper stage. 19. Apparatus according to subrevendi'oation 18, ca.ract6 ris6 in that the outputs of the aforementioned stages; one of the aforementioned switches, to obtain signals of determined frequency. 20. Apparatus according to sub-claim 17, characterized in that the end-of-action photo-diode is connected to the input of the second flip-flop so that said second flip-flop is, after passage of the signals delivered by the position, brought back to its previous state by m, impulses engendered by said end-of-action photo-diode. 21. Apparatus according to sub-claim 17, characterized in that the second flip-flop has its output connected to the port of the first flip-flop so as to suppress the signal transmitted by said first flip-flop to the aforesaid station. 22. Apparatus according to sub-claims 15 to 17, characterized in that it comprises, for the reverse drive of the film, two additional photo-diodes identical to the end-of-action or db photo-diodes, goal of action, and diametrically opposed to the latter. 23. Apparatus according to sub-claim 22, characterized in that an inverter relay, powered by an am pfifier, itself controlled by a flip-flop, makes it possible to substitute one of the pairs of photodiodes for the other. 24. Apparatus according to claim II and sub-claim 17, characterized in that for the programming of the projection of a document, it comprises two oscillators connected to the input of a recording device, these oscillators 6tant tuned to different frequencies and connected to the output of one of the aforesaid amplifiers and two detectors connected to the output of said recording device, these detectors being tuned to the same frequencies as the aforesaid oscillators and connected to the input of the first aforesaid flip-flop. 25. Apparatus according to sub-claims 23 and 24, characterized in that the output of the aforesaid amplifier is connected to one or the other of the pre-kit oscillators by means of an inverter actuated by the aforesaid relay. 26. Apparatus according to claim II, characterized in that it is provided with a mechanism for advancing the film which is simultaneously subjected to an alternating vertical movement thanks to a cam connected to the fax bearing the shutters and to an alternating movement controlled by by the claw input and output electromagnet. 27. Apparatus according to sub-claim 26, charac terized in that the first film advance mechanism is Ions ti killed by an articu16e bielfette, at one of its ends, to a rod integral with the core of said 61eatro-magnet and provided, at its other end, with a claw engaging in the perforations of the film. 28. Apparatus according to sub-claim 27, characterized in that the rod comprises a frame Jans which engages the aforementioned cam, said frame having sufficient dimensions to allow the first translational movement of said rod. 29. Apparatus according to sub-claim 26, characterized in that the film advance mechanism further comprises a rod provided, at one of its ends, with a counter-claw and hinged, at its other end, to one of the arms of an oscillating lever, the other arm of which is hinged to said rod, so that said rod and said rod perform, at each instant, identical movements and in opposite directions. 30. Apparatus according to sub-revendilcation 27, characterized in co quo ia. bielfette cited above has two lugs engaging in guides or vertical corridors fitted, Jans leer central part, with slats which prohibit the translation of the connecting rod perpendicularly to the plane of the film outside the two pomts: extremes of its vertical displacement.