DE2751556A1 - RUNNING PROJECTOR, IN PARTICULAR FOR SMALL FILMS - Google Patents

Description

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DH. K. ν. I'KCHMANN DH. IN". D. BEHHENS """"^{<089> β} ° ^S ° "

DIPI. ING. R. GOETZ 27 5 ^ 556

ATENTATORS PATENT LAWYERS pboteotpatkkt

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Applicant; Vireco, AG

Bahnhofstrasse 94, CH-8001 Zurich, Switzerland

Title: motion picture projector, in particular

for 35mm films

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DESCRIPTION

The invention relates to an apparatus for projecting motion pictures in which the film is continuous is transported.

The advantages of a motion picture projector with continuous film transport compared to conventional projectors offers intermittent film transport have been known for some time. The main advantage is that the wear of the film is reduced to a minimum because the film does not transport intermittently or jerkily will. In devices with intermittent film transport, this jerky movement often leads to damage of the film at the perforations, as a result of which cameras and projectors occasionally experience inhibitions caused by torn off Causing fragments of the footage; it also happens that the film breaks.

In a device with continuous film transport, an optical compensator is required to compensate for the Movement of the individual frames of the film in relation to the image window. The main disadvantage of such devices is that in practice it is difficult to find a usable, optimal

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see creating compensator. With an already known one Compensator is a mirror that can be swiveled to and fro.

The structure and mode of operation of devices with continuous Film transport in which there is a mirror that can be swiveled back and forth will be explained below with reference to 1 to 4 explained in more detail. Here shows:

1 shows a schematic representation of a device with a mirror that can be pivoted to and fro;

2 shows a schematic representation of a mirror that can be pivoted back and forth by means of a cam;

3 shows the light beam diagram of a working with a mirror Projector; and

Fig. 4 is a light beam diagram showing the influence of dimensions of the mirror illustrated.

In the arrangement of FIG. 1, a film 11 is continuously transported in the direction of arrow 12 and through a curved film guide so that a part of the film along a circular arc 13 with the center 14 emotional. The circular arc 13 is arranged in front of a picture window 15, which determines the length of the film section, each can be viewed at a given point in time. More precisely, the length of the image window corresponds to 15 the total length of two frames of the film, hit the light rays 16 falling through the image window.

According to FIG. 1, there is a mirror 17 which can be pivoted about an axis which extends through the center of the circular arc 13 extends. A drive device, not shown,

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moves the mirror so that it has a relatively slow scanning movement executes in the forward direction beginning with position 17a and ending with position 17b. The mirror moves with a constant angular velocity, which is chosen so that he in the described movement one The individual image of the film 11 follows, while the individual image is opposite the image window 15 from a position in which the center of the frame is at A, moved to a position where the center is at B. If the central angle of the circular arc A-B is denoted by 0, the mirror 17 must be rotated between the positions 17a and 17b the angle Θ / 2 can be swiveled. This ensures that the optical image of the individual image is in the direction of the arrow 18, i.e. in a constant direction, is reflected. Thus, the movement of the mirror guides the scan in the forward direction to the fact that the relevant frame is apparently brought to a standstill. The mirror 17 forms a component of an optical system to which one or more projection lenses belong, by means of which a Image on a screen 20 is designed.

After each scanning movement in the forward direction, the mirror 17 is quickly returned to the position 17a, whereupon will begin scanning forward for the next frame. For those working with continuous film transport It is precisely this return of the mirror that most frequently leads to difficulties in practice.

Although attempts have been made for a long time with continuous film transport To create working devices, very few practically useful devices are known up to now become. One of the most tried and tested devices in practice is in a paper entitled "Continuous Motion Picture Projector for Use in Television Film Scanning "by A.G. Jensen, R.E. Graham and CF. Mattke in the" Journal of the Society

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of Motion Picture and Television Engineers ", January 1952, p. 1. The following is for simplicity for the sake of speaking of the work of Mattke and the aforementioned projector.

Regarding a simple mirror that can be swiveled back and forth Mattke states that such a mirror "is obvious for use in a practical device not suitable ". Mattke uses several mirrors which are arranged on a drum in such a way that it is not necessary is to quickly return each mirror after the completion of the forward scan, since each mirror ends up its forward scan through the next mirror is replaced, which then takes the correct angular position to start scanning forward for the next Start single frame.

Other suggestions have been made with the aim of avoiding the difficulties inherent in simple setbacks to and fro mirrors result. For example, US Pat. No. 2,770,163 describes an arrangement in which there are two pivotable mirrors, and in which a device for shifting a light beam shifts the projected light beam from one mirror to the other mirror to make alternating scans in the forward direction so that each mirror can slowly return to its original position, with this movement occurs during the forward scan period of the other mirror. These known devices, i.e. both those equipped with a mirror drum and those with the displacement of a light beam are of complex construction, unreliable to operate and expensive.

The invention is based on the object of an expedient

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To create compensation device in which only a single simple to and fro swiveling mirror is used, and which is particularly reliable.

Fig. 2 shows a type of device with a reciprocating mirror, in which the mirror by a Cam is actuated. As with the arrangement according to FIG. 1, the film 11 is transported with respect to a picture window 15, wherein in each case a single image A-B of the film at the center point 14 defines a central angle θ. The mirror 17 is on one End of a cooperating with a cam 23 movement take-off arm 22 attached with the length r. The other end of the Arms 22 is supported on the cam 23, which is rotated about an axis 24 in synchronism with the film 11, which in the direction of arrow 12 is transported. The cam surface 25 of the cam 23 has such a shape that the mirror 17 the individual images of the film is tracked exactly. The mirror is returned to its original position as soon as the end of the arm 22 falls along a step 26 of the cam which has the height s. According to FIG. 2, this return movement brought about by a torsion spring 27.

If a practically usable system with a back and forth swivel In particular, if mirrors are to be created, it is necessary to avoid the difficulties that arise regarding the achievement of the required return speed result. If the reset speed is too low, the viewer's eye has time to watch the image jump back on the screen, and at this point appears the projected image is blurred. The lower the reset speed is, the more blurred the projected image will be.

To increase the resetting speed of the mirror, the resetting force acting on the mirror can be increased,

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which can be applied by a spring such as spring 27 shown in FIG. However, the strength that comes with A certain mirror arrangement can be applied, limited by the fact that it is necessary to use the mirror at the end of the Bring the return movement suddenly to a standstill. When large forces are applied, each return movement occurs at the end strong mechanical shocks, which cannot be allowed in particular because these shocks with occur at a frequency of at least 16 impacts per second. In order to reduce the impact forces, it is therefore necessary to reduce the weight of the mirror and the associated mechanical Keep parts as low as possible.

In the arrangement according to FIG. 2, the return speed is determined according to the inertia of the mirror 17 and the arm 22 in relation to the pivot axis 14. The moment of inertia of arm 22 increases with the square of its length r and its mass. The greater the length of the arm 22, the greater must be its thickness if its strength is to be sufficient, and therefore the moment of inertia of the mirror mechanism decreases with the length r of the arm increases very quickly. If a short reset time is to be achieved, it is therefore important to use the Length r of arm 22 to make Icle in as much as possible.

The length r of the arm 22 can be reduced by moving the cam 23 closer to the mirror 17, and that at a given pivot angle Θ / 2, the height s of the step 26 of the cam is reduced. However, the height can be at level 26 do not reduce it at will. The lower the level 26, the greater the influence of small irregularities the cam surface and an existing play in the bearings of the axis 24. This increases the accuracy the scanning movement in the forward direction is affected.

After looking for the height of the step of the cam the smallest

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Has chosen possible value, the length r of the arm 22 can be further reduced by moving the cam 23 closer approaches the mirror pivot axis 14. However, this increases the scan swivel angle θ. You could assume that the resetting of the mirror occurs faster the smaller the scanning angle, but one results Enlargement of the scanning angle only corresponding to a first order of magnitude to influence the reset time while there is an influence on the moment of inertia of the mirror mechanism in the opposite sense, that of the second Order of magnitude.

More important than the use of an arm 22 with a small length r is the use of a mirror which is small Has dimensions and is therefore light. A small mirror does not only show slight inertia as such, but it does also enables the use of a support structure and in particular a motion absorbing arm of lower strength and lower weight.

3 shows schematically the essential features of an optical system for one equipped with a mirror Projector. For the sake of clarity, the real light rays are shown with solid lines, while those of the reflection are indicated by the mirror corresponding virtual light rays with dashed lines. In Fig. 3 are the object of observation formed by a single image f, the To see mirror 17, the projection lens L and the screen. According to FIG. 3, for a given size of the Subject f possible to reduce the dimensions of the mirror by making the mirror as small as possible Distance from the projection lens L is arranged. However, it can be seen from Fig. 3 that the dimensions of the mirror do not can be reduced when you move the film closer to the mirror in order to reduce the individual

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to achieve images, as indicated at f1. According to the invention, however, it has been found that this conclusion is wrong, and that there is a considerable reduction in length in an arrangement with a pivoting mirror of the swivel arm and thus the inertia can be achieved if the distance between the mirror and the film is reduced. This can be seen from FIG. 4.

FIG. 4, which is similar to FIG. 3, shows an arrangement in which a single image f forming the object is on the pivot axis 14 of the mirror 17 determines a central angle 0, which is not necessarily small, but at which a practical Limit by which the largest angle θ is determined. After this largest angle has been determined, one can check whether it makes sense to move the film closer to the mirror. According to FIG. 4, one needs further removed film f a mirror with the length M, while at a smaller distance a smaller frame f1 of the mirror the length of the mirror only the distance M «. correspond to which is shorter than the distance M. Since the ratio between length and width of a single image is usually is kept constant, a reduction in the length leads to a corresponding, but not necessarily proportional decrease in width. Thus you can reduce both the width of the mirror and its length, whereby the mass of the mirror decreases with the square of the length M. Such a reduction in the mass of the mirror not only leads to a reduction in its moment of inertia, but it also enables a lighter one to be used Lever arm 22, whereby the inertia is further reduced. The inertia of the mirror about axis 14 is proportional to the product of the mass of the mirror and the square of the segment M. Overall, the inertia of the mirror system is determined by determines a size that is greater than M. With that in mind the reset time of the mirror can be shortened considerably,

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if you place the mirror at a smaller distance from the film. This is a surprising result, because one would normally assume that it would help achieve a quick one Resetting the mirror is most expedient to provide a small scanning angle θ and the film in a large one To arrange distance from the mirror. In developing the invention, however, it was found that the opposite is true.

The object on which the invention is based is characterized by its refinements in the claims Motion picture projector solved.

It has been found that when the above conditions are met, a mirror reset time is possible short enough to allow noticeable obscuration of the image on the screen itself then to be avoided if a rotating screen is not used. For this purpose, the mirror system has to be very small and easy to train, and contrary to an obvious expectation, one must measure the distance between the mirror and the film and reduce the dimensions of the individual images compared to known arrangements and not increase them. In fact, it has been shown that the size of the individual frames of the film should be considerably smaller than even with the usual 8mm films. The invention provides a motion picture projector that operates with continuous film transport using the findings and procedures discussed above.

More specifically, the invention provides a continuous film transport projector for films with a Sequence of frames has been created, the means for continuously transporting the film along a Has film web, furthermore a compensation mirror, the one axis can be swiveled back and forth, one with the mirror

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coupled lever arm for pivoting the mirror back and forth, a movement decreasing section with which the lever arm is provided is, a cam with a profiled cam surface with which the motion pickup section cooperates, means for driving the cam in synchronism with the film transport so that the mirror appears at each frame a forward scan movement at the same speed and follows in phase with the passage of the frame to compensate for the movement of the frame, the Mirror jumps back after each forward scanning movement in order to scan the next frame for the next movement to be ready, as well as a projection lens that is on the side of the mirror facing away from the film and in a is arranged a small distance from the mirror, wherein the mirror scans a film section on the film path, the has a length of not more than 5 mm. Preferably, the length is that which is scanned by the mirror on the film web Section less than 3 mm, but this section can also have a length of up to 4 or 5 mm. With a very short one Scanning distance of the mirror of 5 mm or less, it is possible to have the mirror at a very small distance from that Arrange film without resulting in too large a scanning angle. As explained above, the smaller the mirror can be the closer it is to the film. The larger the scanning angle, the shorter the described one can be Be lever arm. Thus, with this arrangement, the use of a very short film scan distance enables inertia of the mirror system to such an extent that a practically useful device has a A sufficiently short mirror reset time can be achieved. It has been found that it is possible to have such short partial times to achieve that a satisfactory image quality can be achieved without using a rotating aperture. Through this the construction is simplified and the light transmission efficiency is increased.

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It can be seen that with the arrangement described above, it is necessary to use a film in which the frame division is not more than 5 mm and preferably 3 mm or less. In a preferred embodiment of the invention, with an individual image division of 2.1 mm worked. The distance between the mirror pivot axis and the film web is preferably no more than 15 mm, and expediently a gap of only 7 mm or less. In the preferred embodiment, the distance 6.5 mm. Accordingly, in the preferred embodiment, the distance between the mirror and the the end of the projection lens adjacent to it as well 6.5 mm «

The very small dimensions of the individual images, which are required according to the invention, offer besides the possibility The use of a simple oscillating compensation mirror has another special advantage that is in it is that a large number of frames can be accommodated on a film of a given length, so that the running speed of the film can be reduced, thereby reducing film wear. From even bigger What is important, however, is the fact that a film of a given length has a long running time, so the films take up considerably less space compared to known arrangements. This results for the first time in the Ability to use motion picture films placed in a cassette or cartridge that can easily be inserted into a viewing device and contain films with a running time suitable for practical purposes. For example In a typical case it is possible to run with a cartridge with dimensions of about 12 χ 7 cm of 30 minutes, which can be doubled if the film has two tracks.

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Since it is necessary to set the compensation level between to arrange the film and the projection lens and small distances between the mirror on the one hand and the film and On the other hand, to provide the projection lens, it is possible to use a projection lens of short focal length. This has the advantage that a projection lens of high quality and with a large aperture can be used can, resulting in a high throughput of light without undue cost. At the same time, there are surprising ones Advantages in reducing the inertia of the mirror system through the use of a mirror actuating lever of short length while accepting a larger scanning angle and from the extensive reduction in the distance between the mirror on the one hand and the film and the projection lens on the other.

The drive device for the cam must ensure that the rotational speed of the cam corresponds to the transport speed of the film. This task can be accomplished by having magnetic ones printed on the film or optical signals are sampled, and that an electric motor for driving the cam with the aid of these signals is controlled so that the cam is synchronized with the film. Preferably, however, a direct mechanical one Coupling between the cam drive and the film transport device present, in the form of friction rings or a sprocket. With regard to the use of a sprocket drive, there are fewer objections when the Film moved continuously as if it were being fed intermittently.

Furthermore, the drive means for the cam must be designed so that each forward scanning movement in the correct Point in time begins. Because the film may have been stretched or shrunk, and slippage possible

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is, a friction drive does not always lead to perfect phase synchronization between the cam and the individual frames of the film. Therefore you can also use a spiked roller that works with the perforation of the film. Alternatively, however, it is possible to view the film at regular intervals and in a permanent relationship to the To arrange individual images magnetic or optical synchronization markings, with which a magnetic or optical Detector cooperates on the passing Synchronization marks responds to adjust the cam so that a perfect phase synchronization results.

In a preferred embodiment, the phase synchronization effected the device with the help of a kind of escapement; this is the driving force for the cam transferred mechanically from the filrate transport device via a device that enables slippage, and there is a locking member which is engageable to permit movement of the cam as required to interrupt and that can be disengaged to release the cam. As long as the locking member is in Is engaged, the slip-permitting device allows a slip, but the driving force becomes Immediately transmitted again when the locking member is rendered ineffective. The locking member is electromagnetic with the help an electrical impulse is released, which is generated each time a corresponding individual image Reference mark is detected. Such an inhibition is in a simultaneous with the present application application filed by the applicant (patent attorney file number 1A / G-50 118).

Embodiments of the invention are based on the following Schematic drawings explained in more detail. It shows:

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Fig. 5 is an oblique view of a cassette film projector according to the invention ;

6 is a view similar to FIG. 5, from which the main parts of the projector are visible;

7 shows an oblique view of a Ktessette receiving device and a film cassette;

Fig. 8 is a view of the cassette receiving device;

Fig. 9 is an enlarged view of a portion of a film contained in the cassette of Fig. 7;

10 shows a representation to illustrate the mode of action the mirror system of a projector according to the invention;

11 shows a side view, partially drawn in section, of a structural unit or a module that comprises the mirror system the projector of Figures 5 to 8 includes;

FIG. 12 shows the front of the module according to FIG. 11; 13 shows the section IV-IV in FIG. 12; FIG. 14 shows the section V-V in FIG. 11;

Fig. 15 shows part of another film for use in connection with the cassette of Fig. 7;

Fig. 16 shows part of another film for the cassette of Fig. 8; and

Fig. 17 is a longitudinal section of an optical system for projecting a film according to Figs. 15 and 16, respectively.

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Referring to Fig. 5, there is shown a cassette film viewer to which the invention is applied, to which a case 30 which has a screen 317 and a slot 32 for receiving a film cassette on its front side. When the viewer is turned on after a cassette is inserted into the slot 32, the film becomes continuous transported at a predetermined speed. Light transmitted through the film is focused and onto the back of screen 317 to produce the image to be viewed. About the discernible movement of the individual images To bring to a standstill on the screen, a compensation device according to the invention with a pivotable Used mirror, which is described in more detail below.

The viewing device has a front panel 33 with controls 34 for setting related parts. The film has a soundtrack and there are knobs for setting the volume and timbre of the sound. Other controls are used to adjust the brightness of the image on the screen and to focus the Image.

Further details of the viewing device according to FIG. 5 can be seen from FIG. 6. To the following with reference to Fig. described film cassette includes a take-up reel and a supply reel, which are arranged in a housing made of plastic are. The reels carry a film that is cast by freely rotating rollers between the reels along a straight path to be led. The cassette has an opening that receives a prism when the cassette is inserted into the viewing device, by means of which light is guided through the film.

Used to transport the film in the forward direction a motor 51 which drives a friction roller 52, which in a

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Cutout of the cassette housing protrudes; there is also a spring-loaded pressure roller 52a which against the opposite side of the film to pinch the film between it and the drive roller. The pressure roller is freely rotatable, while the friction roller 52 is driven by a shaft 55 which can be driven by a motor 51 Flywheel 55a is coupled.

A driver 56 engages the core of the take-up reel and is driven by means of a device 57 allowing slipping through with the aid of a belt or belt 58, which in turn is driven by a rewind motor 59. In this way it becomes a constantly effective overtaking force for the take-up reel is generated so that the film transported by the friction roller assembly is wound up.

During the projection process, light from a lamp (not shown ) is fed to the prism 31 h via a heat shielding filter and is reflected back in the direction of a compensation mirror which is arranged in a mirror system module 800, by means of which the apparent movement of the mirror is shown in a manner that will still be explained continuously moving frames of the film is canceled. The compensation mirror reflects the incident light to a projection lens 316 and further to a mirror 318 arranged on the rear side, from where the image is reflected in the direction of the screen 317.

Fig. 7 shows how the film cassette 310 is inserted into the receiving device. The cassette contains zv / ei Coils, one of which can be seen in FIG. 7 at 213; the film 311 is driven by the described friction roller assembly of FIG transports one bobbin to the other.

The cassette is held in a vertical position and according to

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5 inserted into the slot 32. Then a projection button, i.e. one of the buttons 34 of Fig. 5, is depressed, and the cassette is thereby brought into engagement with the dogs 56 and 60 which cooperate with the hubs of the film reels. The prism 314 enters a section 312 of the Insert the cassette so that it reflects collimated light passing through the film towards the module 800. The film 311 is attached to the cutout 312 via a fork 717 guided. When the projection button is pressed, the fork 717 is pulled up to feed the film past a picture window. In addition, a sound head 48 is moved downward and brought into contact with a magnetic sound track of the film, so that the sound recorded on the film is played back.

Fig. 8 shows further details of the arrangement cooperating with the film cassette. The belt 58 is over a The intermediate roller 801 and a belt 802 are driven by the shaft 803 which belongs to the motor 59 according to FIG. 6. This tape runs over wheels 804 and 805 as well as another wheel 8O6, whose axle is normally fitted with a rubber tire 807 on the Co-operation with the take-up reel associated with a slip-through device 57, via which the take-up reel is driven.

The wheels 804 and 805 are mounted on a sliding plate 803, and when a fast advance of the film is desired 5, one of the push buttons 34 is actuated so that the wheel 806 is lifted from the rubber tire 807 and that the plate 308 is shifted to the right by causing wheel 805 to drive the take-up reel. If the film is to be rewound, a corresponding one is used Another button pressed to pull the plate 308 to the left so that the wheel 304 with one placed on the supply spool Tire 309 cooperates.

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When switching on the s clone lien forward or reverse, a plate is pulled upwards according to FIG be lifted off the film. In addition, the plate 810 carries an elongated cam, by means of which the fork 717 can be raised and lowered so that it releases the film during fast forward and rewind.

In Fig. 9, a part of the film 311 contained in the cassette is shown.

The film includes a base material made of polyvinyl chloride with a thickness of 1.5 mm. The film is 8 mm wide and has magnetic strips on both long sides 411 and 412, each of which is provided with two soundtrack channels to enable stereophonic sound reproduction. The sound track 411 is assigned to a cinema film which is formed by a sequence 413 of individual photographic images, while the sound track 412 belongs to a second similar sequence 414 of individual photographic images.

If the cassette 310 is inserted into the projector, a film track is projected as the film is transported, with the associated audio track is played. If you take the cassette out of the projector and turn it over, the film becomes transported in the opposite direction to project the second film track and play back the second sound track. Each of the individual images of the film tracks 413 and 414 has a width of 2.25 mm, and the individual image pitch is 2.1 mm. A synchronization track 261 with a width of 0.5 mm is arranged between the two image tracks 413 and 414. the Track 261 is made up of alternating transparent and opaque synchronization markings, the opaque markings being photocopied onto the film. In Fig. 9 the transparent markings with 416 and the opaque mar-

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marked with 417. These markings are in precisely aligned with the individual images of the film tracks and 414.

Fig. 10 is a schematic diagram for explaining the operation of the projector. The film is located in the cassette, and in FIG. 10 a part of the cassette housing is indicated at 310. The film 311 becomes continuous transported in the direction of the arrow. The cassette has a cutout 312 where light shines through to be projected Film is directed. The cutout 312 takes a prism 314, by means of which the light of a high-performance lamp, not shown, is guided through the film to be projected will. The projection light is reflected by a pivotable mirror 315 so that it is directed to the projection lens 316 arrives, by means of which an image is generated on the screen 317 after the light has passed through another Mirror 3I8 has been thrown back.

The mirror 312 is swung back and forth so that the apparent Movement of the individual frames of the film that pass through the viewing area is canceled out in relation to the lens 3I6 will. For this purpose, the mirror is pivoted about an axis 319 so that it is in a forward scanning movement in each case follows a passing frame of the film 311. After such a movement, the mirror becomes very fast panned back in order to be able to follow the next single image.

A lever arm 320, which is rigidly connected to the mirror and is located on the cam surface, is used to pivot the mirror a cam 321 which is rotated by means of a mechanical drive device 322 in accordance with the film transport will. The drive device 322 includes a wheel made of rubber and a conical section 324 of a shaft, so that the transmission ratio can be set manually.

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The crouch 321 guides everyone passing the opening 312 Frame one revolution. A leaf spring 325 fastened at 326 according to FIG. 10 is supported on the Hebelami

320 starting to make it into contact with the cam surface of the cam

321 to hold. The cam surface is profiled so that the mirror 315 is within such an angular range is panned so that it follows the frame in question exactly. At the end of each scan in the forward direction the free end of the lever arm 320 drops at a step 327 of the cam, thereby returning the mirror.

It is not enough that the cam 321 is driven precisely in synchronism with the film 311, but it is necessary that every forward scanning movement of the mirror, taking into account the position of the individual image in question, is exactly in the correct position Point in time begins. This phase synchronization is brought about by an escapement. The light from the projection lamp (not shown) is through the prism 314 onto a photocell 329 guided, according to Fig; 9 above the synchronization marks containing track 261 of film 311 is arranged. The electrical signals from the photocell 329 are fed into an amplification and waveform shaping circuit 330, the output signals of which are used to drive an electromagnet 331 of the To excite inhibition. According to FIG. 10, the electromagnet 331 actuates a locking arm 332, which in FIG. 10 is in its normal position occupies, in which it locks a pin 333 built into the cam 321. This prevents the cam from rotating, until the solenoid 331 is energized and the lock arm 332 is withdrawn. Furthermore, a not shown in Fig. 10, a device allowing slippage is present, which makes it possible to stop the cam while the drive device 322 continues to generate a driving force.

According to FIG. 10, there is an adjustable electrical element between the photocell or the sensor 329 and the electromagnet 331

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Delay circuit 501 which introduces a delay corresponding to the time it takes for the film 311 to be The distance to be covered is the distance between an edge of a single image and the associated synchronization mark is equivalent to. This arrangement normally ensures accurate synchronization, but is the delay circuit 501, which is an integrated circuit timer, with a manually operable one Operating element 502 provided, which is coupled to one of the manual controls of the projector, so that one can precisely adjust the delay by hand to ensure accurate synchronization. The area within whose delay can be changed, corresponds to the processing time of a little more than a complete frame division.

In Fig. 11 to 14, a module is shown, which is an inventive Includes mirror system generally equivalent to that described with reference to FIG. Hence the concerned Parts with the same reference numerals as in Fig. 10. The module contains the mirror 315, which according to Fig. is stored in bearings 701. A coil spring 702 keeps these bearings under uniform bearing pressure. The mirror 315 is made of glass, it has a thickness of about 0.25 mm, and it is provided with a reflective coating so that the reflected light does not penetrate the glass.

The movement reducing arm 320 is rigidly connected to the mirror and is supported on the cam surface of the cam 321. The lever arm 320 according to FIG. 12 points beyond the mirror an angled extension 320a on which one end of a U-shaped leaf spring 325 is supported, the other end of which is attached to the housing of the module.

According to FIG. 11, the cam 327 is seated on a camshaft 341,

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which is driven by a drive shaft 347 mounted in the projector via a slip clutch. At the drive shaft it is the shaft of the motor 51 driving the friction roller. The slip clutch consists of two Clutch plates 342 and 348; the clutch disc 342 is seated on the camshaft 341, while the clutch disc 348 in the housing of the module by a slotted snap ring 703 is being held. The clutch plates have cooperating conical surfaces which are biased against one another by the spring force of an elastic plate 704. In the plate 704 is a plug 705 made of plastic, which has a bearing surface which against the adjacent End of the camshaft 341 is biased. From the drive shaft From Fig. 347, the driving force is applied to the clutch disc 348 by an end portion resembling a screwdriver 706 of the drive shaft and a slot 707 of the clutch disc 348. This arrangement enables the Bring drive device into or out of engagement when the module is inserted or removed from the projector will. According to FIG. 11, the module is held in its position by a fastening screw 708.

13 shows the electromagnet 331 with the associated one Locking arm 332, which is not retractable in the manner shown in FIG. 10, but with the aid of its end 709 is pivotally mounted, which is held in contact with a pole piece 710 of the electromagnet, namely by U-shaped resilient clips 711 with inwardly protruding Indentations 712 are provided which cooperate with the locking arm and the pole piece. Another pole piece 713 of the Electromagnet is positioned over the other end of lock arm 332 so that the lock arm is sandwiched between the pole pieces forms extending armature, which is magnetically attracted and brought into a horizontal position as soon as the electromagnet is excited by a synchronization pulse. At the

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Switching off the electromagnet falls under the lock arm Effect of its own weight down to take its locked position. In the free end of the locking arm 332 is a Installed locking pin 714 which engages pin 333 built into cam 321 when the locking arm moves is in its locked position. If the locking arm is pulled back into its release position by the electromagnet 331, it lies outside the path of the pin 333.

The circuits 330 and 501 according to FIG. 10 are arranged together on the electromagnet 331 and in FIGS. 11 to 14 not shown separately. They are connected to the photodiode 329, which can only be seen in FIG., That of the synchronization markings light coming on the film is fed via an optical fiber bundle, the end of which is 715 is shown in FIG. A is used to set the delay of the circuit for triggering the electromagnet Trimming device, not shown, which corresponds to the device according to FIG. 10 and by means of a screwdriver is accessible.

Fig. 11 shows the position of the film 311 when the cassette is inserted into the projector. The module housing 808 has a Image window 716 under which the film guide fork 717 is arranged, which is attached to a plate 718 according to FIG. 14, which is slidably guided in the module housing and is normally biased downward by a spring 719. According to FIG. 14, an angle lever is on an axis 721 720, which cooperates with the plate 718 to move it upwards against the force of the spring 719, so that the film is brought to bear on the edge of the image window 716. This happens when an approach 722 of the Angle lever 720 is pressed inward with force, namely by an elongated sliding cam 723, which is pushed down in the direction of the arrow,

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if you press a push button with your hand to turn the Initiate film transport. According to FIG. 14, the cam 723 is arranged on a plate 808.

At the image window 716, the film is guided along a curved path, i.e. not along a straight path as in FIG 10. More precisely, the film moves at the image window along an arc of a circle, the center of which is shown in FIG 12 lies on the pivot axis 319 of the mirror 315. in the In contrast to the arrangement according to FIG. 10, the squat 321 must therefore be given a different profile. The curvature of the film web has the advantage that the distance between the film and the projection lens is not changed during the scanning process, but this also results in certain disadvantages. Since the film flexes in one direction while maintaining its planar shape at right angles thereto, one occurs certain different deformation. In addition, the film can be subject to more wear than one straight film guidance. In practice, therefore, the film web can be straight or have a curvature less than that an arc of a circle whose center point lies on the pivot axis of the mirror. In that case one would be involved in the construction of the projection lens have to take into account the respective course of the film path.

In practice, reference is made to the use of the means 323 and 324 of FIG. 10 to adjust the speed of rotation of the cam waived. Rather, the cam is driven by gears so that it is a small amount of e.g. rotates 1% or less faster than necessary to synchronize with the film. Thus it results a very short dwell time for the cam controlled by the electromagnet 331 for each frame of the film. Has If the film experiences shrinkage, a short dwell time is available, which is due to the faster occurring

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Synchronization pulses is abbreviated. If the film has stretched, the dwell time increases.

The parts of the device of FIGS. 10 to 14 have extremely small dimensions, and the film 311 has a very small frame division. This small single image division is made possible In conjunction with the small distance between the film and the mirror 315, the mirror system is sufficient to train small, so that the mirror can be returned very quickly. The embodiment described here If, for example, the distance between the mirror pivot axis 319 and the film is 6.5 ram, the image window has a length of 4.2 mm, which is twice the frame division of the film of 2.1 mm, the length of the lever arm 320 is 14 mm, the cam 3? -1 has a maximum radius of 5.5 now, and the height of the step 327 of the cam is 2.2 mm. The projection lens 316 has a focal length of 13 mm. Of the Distance zv / ischen the mirror pivot axis 319 and the part of the projection lens that is closest to it 6.5 mm. The mirror is made of glass with a thickness of about 0.25 ram. The shape of the mirror is of particular importance. According to FIG. 11, the mirror tapers in one direction, so that it is larger near the projection lens Width than in the middle of the film. This irregular The shape of the mirror corresponds to the shape of the cone of light falling on the mirror, and it is possible to measure the weight of the To reduce the mirror to a minimum by leaving out those parts that are not struck by light will.

The largest dimensions of the mirror are 12 χ 7 mm, and the mirror has an area of 69.1 mm. Its weight is 100 mg. The movement decrease arm has together with its bearing pins a weight of 300 mg. The spring constant of the return spring is 3 g / mm. The spring works

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on the lever arm with a preload force of 5.6 g. The contact pressure between the lever arm and the cam surface is 1 g.

The film handling and projection arrangements described above are for projecting both black and white films as well as color films. Fig. 15 shows a film format which enables a black and white film to be used for color projection to use. This Filraformat is the same as that shown in Fig. 9 except that within each image track each individual image, e.g. the individual image 451, into three sub-images, e.g. the displayed sub-images 45IR, 45IB and 45IG. While exposing this Film, the partial images are exposed through an associated red, blue or green filter, so that within the three partial images different color separations of the same scene are available. When projecting, the partial images are on reunited in a manner yet to be explained with the aid of associated filters, so that a composite color image is created. With this format, the partial images have a shorter length and it may be desirable to reduce the overall division of the Enlarge single images to 4 ", 5 or 5 mm, \ un the desired one Restore image sharpness.

Fig. 16 shows another film format in which the partial images extend parallel to one another in the longitudinal direction and not as in the format of FIG. 15 transversely to the film. To expose a film according to FIG. 15 or 16, one needs of course a distortion lens, by means of which the aspect ratio of the partial images is changed accordingly. At the A distortion compensator is then used in the projection process.

Fig. 17 shows an optical arrangement for projecting a film of Fig. 15. The film is made by means of the arrangement

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scanned according to Fig. 6, to which the mirror 315 and the Lens 316 belong. If there were no compensation device, the image projected onto the screen would consist of the three color separations arranged one above the other put together. The compensation device according to FIG. 17 includes a beam splitting prism 452, by means of which the Red, blue and green extracts are projected along associated ray paths 453R, 453B and 453G in which associated Filters 454R, 454B and 454G are arranged. Steer mirror 455 the rays of light towards a reunification prism 456 um, whereupon the color separations are projected together onto the screen through the lens 457.

Because of the aforementioned distortion, the prism 456 is provided with diverging cylindrical lens surfaces 458 through which the aspect ratio of the partial images is restored by spreading in the corresponding direction.

The optical system of FIG. 17 can also be used to project the film of FIG. For this it is only necessary to rotate the compensation device with the prisms 452 and 456 and the filters by 90 °, because in the absence of one Compensation, the three color separations would appear on the screen next to each other and not in line with each other.

Various modifications are possible within the scope of the invention. As already mentioned, you can use a film guide which is less curved than a circular arc, and the use of a straight film guide is also possible. In these cases, the stated distances between the mirror and the film are to be regarded as mean distances.

Although the synchronization inhibitor described is preferred Use has been made, but the invention is not limited thereto. The cam can be driven by the film itself

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be derived, either by frictional engagement or with the help of a pinwheel that works together with the perforation of the film. Against this use of the perforation is less objectionable in this case, since the film is transported continuously and not intermittently will.

Of course, the invention can be applied not only to a projector with a screen, but also to devices of the type described by Mattke for converting film images into television images. The invention is also at Motion picture cameras applicable, which are provided for this purpose with a mirror scanning device according to the invention can.

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Claims (8)

PATENT CLAIMS 1. Motion picture projector, especially for 35mm films, in which a motion picture film with a sequence of individual images is continuously transported, with a device for continuously transporting the film along a Film track, a compensation mirror that can be swiveled back and forth about an axis, one that is coupled to the mirror Lever arm for pivoting the mirror back and forth, a movement pick-up section formed on the lever arm, a cam with a cam surface with which the movement take-off section cooperates, means for driving the cam in synchronism with the film such that that the mirror each frame during a forward scan at the same speed and in phase with the passage of the frame follows to the To compensate for movement of the frame, the mirror jumping back after each forward scan movement in order to ready for the forward scan of the next frame to be, and a projection lens on the side of the mirror facing away from the film, characterized in that the projection lens in one small distance from the mirror (31 * 5) is arranged, and that the mirror on the film path scans or sweeps over a distance of no more than 5 mm. 2. motion picture projector according to claim 1, characterized in that that the distance that the mirror scans or sweeps over the film path is 3 mm or less. 3. motion picture projector according to claim 2, characterized in that the distance 'which the mirror on the film web scans or scans, is about 2.1 mm. «09822/0693 ORIGINAL INSPECTED 50 123 2 7 5 I b b 4. motion picture projector according to one of claims 1 to 3, characterized in that the distance between the mirror pivot axis (3 ^ 9) and the film path is 15 mm or less. 5. motion picture projector according to claim 4, characterized in that that the distance between the mirror pivot axis (319) and the film web is 7 mm or less. 6. motion picture projector according to one of claims 1 to 5, characterized in that the lever arm (532) cooperating with the cam (321) has a length of approximately 14 mm. 7. motion picture projector according to one of claims 1 to 6, characterized in that the mirror (315) has a tapering shape and on its projection lens (316) adjacent end is wider than at its end adjacent to the film (311). 8. motion picture projector according to one of claims 1 to 7, characterized in that the 3pieg ^ is ^ stim ^{7 is assigned} a ³ film guide device (717) to guide the film relative to the mirror pivot axis (319) along a curved path. 9. motion picture projector according to claim 3, characterized in that that the film guide device (717) is designed so that it guides the film (311) along an arc of a circle, the Center on the mirror pivot axis (319). 10. motion picture projector according to one of claims 1 to 9, characterized in that the mirror (315), the cam (321) and the movement acceptance lever arm (320) in a module (8 00) that can be removed as a structural unit from the motion picture projector are arranged. §098 * 2/069 $ ORIGINAL INSPECTED 50 123 275 lbbb 11. motion picture projector according to a d5 r claims 1 to 10, characterized in that it is suitable for receiving a film contained in a cassette, that of the mirror system associated therewith is a film guide device (717) by means of which the film (311) as it is transported within the cassette is guided opposite the mirror (315) along the gev / ünschten film path that a friction roller drive for driving the Film is present- that a light source with a lamp and a reflector for transmitting light through the film towards the mirror, and that one (329) Synchronization device for detecting synchronization marks is present on the film. 12. motion picture projector according to claim 8, characterized in that a light detector (329) for synchronization is present, which is arranged so that it is struck by light passing through a along the central axis of the Film extending synchronization track (261) falls that the frames are arranged on the film so that there are two Form tracks on both ^ sides of the synchronization track, and that the reflector and the mirror (315) are arranged so that each frame track of the film of viewing is made accessible. 13. motion picture projector according to one of claims 1 to 12, characterized in that there is no rotating screen, 14. Motion picture projector for continuously transporting a motion picture film with a sequence of individual images, characterized by the combination of the following Characteristics: 1) a device for continuously transporting the Films (311) along a film path, 2) a compensation mirror (315) around an axis about 6.5 mm from the film web 8 O 9 8 2 2/0 6 9 3 50 123 2751656 (319) can be swiveled back and forth, 3) a lever arm (332) with a length of about 14 mm, the is coupled to the mirror and serves to swing the mirror back and forth, 4) a movement pick-up section formed on the lever arm, a cam (321) with a profiled cam surface with which the movement pick-up section cooperates, the crouching a step (327) allowing the mirror to spring back with a height of about 2.2 mm at v / ice; 5) drive means for driving the cam in synchronism with the film so that the mirror each frame during a forward scan at the same speed and follows in phase with the passage of the individual image in order to compensate for the movement of the individual image, with the mirror springing back after each forward scan movement, to be ready for the next forward scan on the next frame, 6) a projection lens (316) on the side of the mirror facing away from the film and at a small distance of the mirror, 7) whereby the mirror on the film path scans or sweeps over a distance of about 2.1 mm, 8) and wherein the mirror, the cam and the lever arm are arranged in a module which can be removed from the motion picture projector and which has a device by means of which the film is guided along an arcuate path , the center of which lies on the mirror pivot axis. 809822/069 $