DE2530797A1 - Recording and reproduction method for sound films - uses sound track which runs on film parallel to pictures and offset to achieve synchronisation of sound - Google Patents

Abstract

Corresponding pictures and sound are recorded on a cine film next to each other, with the sound recording on the film made in space after the film exposure, but with a delay in the sound channel, so that the film running time between the exposure gate and the recording head is compensated. During projection of the film the sound track sanning is done before the film reaches the projector gate. A delay is produced, corresponding to the film running time between the reading head and gate, so that the corresponding picture and sound components appear simultaneously.

Description

@@@@@@@ process with spatially in-phase and phase-locked image and soundtrack.

Previous system: In the currently existing sound film systems, at where the sound is in a suitable form (magnetic track, light sprout writing, etc.) on the Footage itself is saved because of the jerky guiding of the film at the point of the picture window and the necessary continuous guidance at the Place the sound head a mutual spatial distance between the picture window and Sound head unavoidable.

The distance between the picture window and the tape head is denoted by a 1 so when picture and sound are recorded at the same time, picture and Sound parts stored on the film shifted against each other by this distance ol (Fig.1). The same spatial distance from al between the picture window and the sound head must must also be adhered to with the projector used, so during playback of the film belonging together image and sound parts are reproduced at the same time. Since the combination of different recording and playback devices is also possible must be, a uniform picture window-soundhead spacing must generally be maintained will.

The disadvantages of this system are when cutting individual film scenes and the necessary definition of the picture-sound distance on the film (all recording and playback devices must have the same distance between the picture window and the sound head).

New system: The procedure described below enables the Recording and playback of sound films with spatially in-phase and phase-locked Image and sound track, i.e.

Corresponding picture and sound parts are right next to each other saved with the film. As with conventional sound film systems, it is because of the different demands on the film management also here a mutual one Spatial distance between the picture window and the sound head is essential.

Assuming a given picture window - sound head spacing al1 and an assumed film speed v1, then the running time of a film is element between the image window and the tape head # t1 = ###. Looking at conventional Recording of image and sound on the film directly adjacent image and sound parts and compares this with the original scene, the picture is different from the sound at1 moved. Since the film first passes the picture window and after ali the tape head, the sound appears ahead of the picture by tt1.

In order to ensure that related image and sound parts are in phase, d .. are stored directly next to each other on the film, this shift must be To get picked up. When recording the sound film, the sound is first stored temporarily and after the time At1, if the associated and already stored picture element the tape head happened on the film, dubbed (copied) onto the film. Thereby are Image and sound parts belonging together are stored next to one another on the exposed film (Fig. 2).

A magnetic tape loop is used as a sound carrier to delay the sound an I, agnetfolienscheibe or the film itself is used. By mechanical coupling between the continuous film advance guide and the audio delay medium ensures that the delay of the tone is always the same as the running time of the Between the image recording window and the sound head is (at1).

This ensures the phase rigidity of picture and sound.

In Fig. 3 the process for recording is shown schematically, if a magnetic tape loop is used to delay the sound. The film happens, as in a known manner, first a film transport roller (1), then the image recording window (2) uni another film transport roll (3).

The electrical sound signal coming from the microphone is amplified and a recording head (4) which stores the data on the magnetic tape loop (5) makes.

The playback head, which is also located on the magnetic tape loop (6) converts the magnetic sound signal delayed by At1 back into an electrical sound signal. This is reinforced and known with the help of the in Way behind the film transport roller (3) seated take-up head (7) on the magnetic track of the film. The magnetic tape loop is driven by mechanical means Coupling (8) with the continuous film transport guide (e.g.

Leadership role 3).

Fig. 4 shows the principle when using a magnetic film disk (9) as a sound delay medium. With direct mechanical assembly (10) on the shaft of a The film transport roller must have a circumference that is larger than the image window - sound head spacing. The arrangement of the recording and playback head (4 and 6) on the Disc is chosen so that the sector of the circle used for deceleration is the same the angle of contact of the length of the film image window - sound head on the guide roller is. To obtain the frequency bandwidth required for the audio frequency spectrum, the diameter of the magnetic foil disc must not fall below a certain value.

The magnetic track of the in the film feed itself can be used (Fig. 5). The distance of the tape heads (4 and 6) used for the delay is exactly the same as the path length of the film between the image window (2) and the sound recording head (7). Because film and sound delay medium are identical, no special mechanical coupling is required.

With each film to be exposed, so does the audio delay medium renewed, which means that there are no signs of wear and tear on the magnetic clay bearing can.

The mechanical film guide can be designed in this way by means of deflection rollers that a favorable overall mechanical structure can be achieved (Fig. 5).

With the listed 3 delay media, i.e. magnetic tape loop, Magnetic sheet and film itself, the process of delay can also be used realize within a film cassette. This is done with each new cassette also renewed the sound delay medium and an intermittent change of cassette, i.e. alternating use of several cassettes is possible.

Fig. 7 shows schematically a film cassette (19) with a magnetic tape loop (29) is installed. The pulleys (20 and 21) allow the formation of loops of the magnetic tape (23) and serve at the same time to deflect the parallel next to it running movie (22). The deflection pulley f21) is movably mounted and takes care of it the spring (25) for constant loop tension.

The continuous drive of the film and the magnetic tape loop occurs through friction between the pressure roller (26) and the drive roller (27). The bearing of the pressure roller (26) is firmly anchored in the cassette, while the Drive roller (27) is part of the film camera and by closing the cassette compartment lock is pressed against the pressure roller (26) after inserting a cassette.

All sound heads required are combined in one assembly (24), as a structural unit of the film camera when inserting the cassette through a cutout comes into engagement in the cassette between the magnetic tape loop (Fig. 8). Of the Gap distance of the opposing tape heads, i.e. the diameter of the tape head assembly, is larger than the diameter of the pulleys (20 and 21), so that the support of the Magnetic tape and the film on the tape heads is guaranteed.

By resiliently mounted pieces of felt (29), which at the same time on the Film and on the magnetic tape, the looping of the film is limited, unavoidable due to the transition from jerky to continuous film transport is. At the same time, the magnetic tape loop is counteracted when changing the cassette Moving secured.

Fig. 9 shows the basic structure of a film cassette (30), in which the delay is carried out by a built-in magnetic film disk (32) will. The disc is driven by friction between the contact surfaces (35 and 5) with inserted cassette, while with removed cassette the magnetic foil disc by: the spring (38) is pressed against the braking surface (34) and thus against adjustment is secured. The audio head assembly (36) is part of the camera and is used in inserted cassette (50) pressed against the magnetic film disc (32). The contact pressure on the magnetic heads (40) is reinforced by a spring with a piece of felt (39). The exposed film (41) is guided in a known manner over the sound head carrier (37), wherein the delayed sound information is recorded on the magnetic track of the film will. From the sound head carrier (37) the film arrives at the take-up reel (51), which passes through a pinion is driven by the film camera.

The playback process is shown in Fig. 6. The film is removed from the supply spool by the continuously rotating film transport roller (12) pulled off and led past a tape head (11). This tape head converts them audio information stored in the film into an electrical audio signal.

At an assumed speed v2 of the film and an assumed Sound head (11) - image window (13) Distance2 is the running time of a film element between tape head (11) and image window (13) # t2 = # l2.

V2 Since the film hits the playback sound head first (11) and after t2 the picture window (you) passes the electrical sound signal rushes to the projected one Image ahead of at2.

To cancel this time shift, the audio signal must be delayed will. A magnetic tape loop is used as a sound carrier to delay the sound by at2 or a magnetic film disk is used.

Fig. 6 shows the scheme when using a magnetic tape loop (15). The electrical sound signal supplied by the sound head (11) is amplified and a The recording head (16) is fed, which records the sound on the magnetic tape loop (15) makes. The playback sound head (17) converts the stored and delayed by At2 Sound signal back into an electrical signal, which is amplified and reproduced will. To ensure that the delay in the audio channel is always the same as the running time of the film between the sound head (11) and the picture window (13), the drive is the Magnetic tape loop (15) by direct mechanical coupling (18) with a continuously rotating film transport roller (z. B. 14) made.

This means that parts of the image and sound that belong together are reproduced at the same time.

The process of sound delay can be used for recording as well as for playback can be performed by an external delay unit. Included the delay must be selected according to the values at1 or bt2 and at the Recording by coupling with the control elements of the film camera synchronously with the film transport can be started and stopped.

This means that conventional film cameras that are still offset can also be used Sound work, be upgraded to the new system. The one coming from the microphone The audio signal is first fed to the external delay unit and the delayed Output signal connected to the microphone input of the camera.

In the exposed film, there are parts of the image and sound that belong together side by side (Fig. 2).

An external delay unit can also be purely electronic Delays set in, which are caused by the currently available electronic It is difficult to integrate storage media into a film camera.

For the necessary delay at a film speed of 18 frames per second and a picture window - sound head distance of 18 pictures equal to one second, the construction volume is too large and the energy requirement too high.

Shift registers and core memories are suitable as electronic storage media, to which the digitized sound information is offered. The electrical sound signal is first converted into digital audio information in an analog-digital converter and saved. After the required delay time has elapsed, the digital Sound information is retrieved from the memory and with the help of a digital-to-analog converter converted into the electrical sound signal, amplified and reproduced.

Advantages of the new system: Since picture and sound are phase-locked and in phase, i.e.

stored side by side without mutual displacement on the film individual movie scenes can be cut and put together without there is a loss of sound or picture.

The picture window - sound head distance and thus At1 in the sound film camera is independent of the sound head - picture window distance and thus At2 of the sound film projector (at1 * t2 das das), that means independence between recording and playback devices. All sound film cameras and sound film projectors can have an individual picture window -To get sound head clearance.

Claims (9)

Claims 1. Procedure for recording and playing back sound films in which the sound track is applied in a known manner as a parallel track to the images on the film is, that no image and sound belong together are stored next to each other on the image-sound carrier, which enables that the recording of the sound on the film is spatially after the exposure of the The film takes place, but with such a delay in the sound channel that the Movement caused by the running time of the film between the image recording window and the sound head is canceled and during playback the scanning of the sound track spatially and temporally in front of the picture window of the projector and by a delay, which corresponds to the running time of the film between the sound head and the picture display window, it is ensured in the playback channel that related picture and sound parts simultaneously be reproduced. 2. A method for recording and playing back sound films according to claim 1, that the delay in the audio channel is in takes place in a known manner by a magnetic sound carrier, in which the Delay is made by spatially offset sound heads, but the The speed of the sound carrier is proportional to the speed of the film. 3. A method for recording and playing back sound films according to claim 1 and 2, d a d u r c h e k e n n -z e i c h n e t that as a magnetic sound carrier a known magnetic tape loop is used, which is driven by a capstan whose peripheral speed is proportional to the film speed, what is achieved in that the capstan with the continuous film transport guide is coupled. 4. A method for recording and playing back sound films according to claim 1 and 2, d a d u r c h e k e n n -z e i c h n e t that as a magnetic sound carrier a known magnetic sheet disc is used, which is attached to the continuous Film transport serving guide roller whose circumference is greater than the length of the Film path between the recording window and sound head, is attached, whereby the peripheral speed the i.fiagnetfolienscheibe is always proportional to the film speed and its Diameter is chosen so that the peripheral speed at the radius of the used Ilagnetspur a frequency bandwidth sufficient to record the audio frequency spectrum enables. 5. A method for recording and playing back sound films according to claim 1 and 2, d a d u r c h e k e n n -z e i c h n e t that as a magnetic sound carrier the The magnetic track of the film in the film feeder itself is used, where the distance between the tape heads used for delay equals the picture window Sound head spacing is the necessary for any film speed Delay is ensured. 6. A method for recording and playing back sound films according to claim 1, d u r c h e k e n n n z e i c h n e t that to delay the tone a external delay unit of known design, which is used both in connection with the sound film camera as well as with the sound film projector can be used, being used by Coupling with the controls of the film camera synchronizes the delay with the film transport can be started and stopped. 7. A method for recording and reproducing sound films according to claim 1 and 6, that the delay of the tone is made possible in a purely electronic way in that the audio signal is digitized and stored in a core memory or shift register and according to the required Delay retrieved and converted into the analog audio signal by a digital-to-analog converter is implemented. 8. A method for recording and playing back sound films according to claim 1, 2 and 4, d u r c h e k e n n -z e i c h n e t that the magnetic sheet disc Is part of a known sound film cassette and through the continuous Film transport is driven synchronously, being ensured when changing cassettes that film and magnetic sheet are locked. 9. A method for recording and playing back sound films according to claim 1, 2 and 3, d u r c h e k e n n -z e i c h n e t that a magnetic tape loop is housed within a known sound film cassette and by a Drive roller, which is part of the film camera and with the continuous film transport is coupled, is driven simultaneously with the film and in which all to delay and recording required heads are combined in a head assembly, with the cassette inserted through a cutout - in the cassette between the Magnetic tape loop comes into play. L e r s e i t e