US2189351A - Television transmission - Google Patents

Description

Feb. e, 1940c F. SCHRTER 2,189,351

TELEVISION TRANSMISSION Filed June 14, 1934' INVENTOR ATTRNEY greater Patented Feb. 6, 1940 UNITED lsinrrss PATENT OFFICE funken Gesellschaft fr Drahtlose Telegraphie m. b. H., Berlin, Germany, a corporation of' Germany Application June 14, 1934, Serial No. 730,593

In Germany July 29, 1933 6 Claims.

The invention relates to the synchronous electrical distance transmission of the picture and tone portion of normal talking films.

It has for its purpose, despite the necessary retaining of the film velocity established by the sound record reproduction, which today by established practice is normally 24 frame widths per second, which may be illustrated by Way of eX- ample, to make possible a higher number of pictures for the optical part of the transmission. It has been found that in the recently attained brilliancies of the picture screen, in particular by the use of the Braun or cathode ray tube (the kinescope) as television picture producer, that the alternation of 24 pictures per second frequently ceases to act sufficiently free of flickering, and that a yquiet facial impression can only be attained at a somewhat higher alternation frequency.

In accordance therewith the present invention resides in the use and combination of methods and arrangements which in the normal, for the tone recording properly adjusted advance of the film, permitsl of the scanning of a great many more pictures at the same time than picture frames of normal dimension are mechanically released. In the following it is assumed, for purposes of example and illustration only, that the required number of optical transmissions per second, herein designated by n, is equal to 36. The invention, however, permits of any other value for n and any desired proportion of this n to the acoustically established value, designated as n', which today=24.

Fig. l shows the relative position of the scanning beams and frames of a continuously moving iilm at different time intervals.

Fig. 2 shows diagrammatically an apparatus for performing the invention.

For the solutionof the present problem an optical picture compensation method is vinserted for the television scanning, and which at keeping constant 1L=normal=24, permits an independent n, n' for the frequency of the light electrical decomposition and recomposition of the picture mosaic. An embodiment of the invention coml prises making a special photographic copy from the talking film to be transmitted, having in the length of 1V=24 normal widths of pictures a number of pictures correspondingly smaller in accordance with the assumption 11:36. The reduction can be limited to the coordinate parallel to the advance of the nlm. This transformation of the respective section of the cinematographic act from 24 tov 36 individual phases or frames can be accomplished in various Ways. One way resides in interconnecting an optical picture balancer between "the original standard nlm and the copy to be made therefrom. In reproducing in this way the uniformly advanced originalnegative, or a positive` made therefrom, by means of a Mechau projector (as illustrated, for example, by U. S. Patent 1,584,317 granted to E. Mechau on May 11, 1926) or an equivalent device with proper reduction, on the step-like advanced copying strip, for example by means of a Maltese cross, and in selecting 36 steps for 24 standard picture frames ofk lm length advanced, due to the continuous excess shutting of the individual picture phases there will be obtained on the copy the desiredincreased number of discrete, sharp pictures of reduced size, and hence 'a film is obtained directly suited for the standard television scanning and which may have the sound record copied atfthe edge thereof.

In another waythe photographic transmission can be carried lout on an auxiliary strip at a rational proportion-nm' for instance also 36/24, by means of special copying machines. These devices operate by the use of rhythmically controlled, and operated shutters in such manner that at a corresponding reduction of vthe size Vof the picture at least of the width 'of the picture in the proportion 36/24, for each 2 pictureframes or phases of the original, three picture frames or phases of the copy are produced, in that, for' instance, each 1, 3, 5, etc., individual picture of the original is twice copied in succession, while each 2nd, 4th, 6th, etc., will be copied only once. Hence for 24 advanced frame Widths of the original 12 times 2 plus 12 times 1,) 36 reduced pictures are obtained in the copy. It is obvious that already at the original production of the respective talking nlm, besides the ordinary apparatus a second apparatus can be synchronously operated therewith which as aforementioned receives for a length lof n standard widths of the picture, directly n, n pictures.

v Besides the photographic compensation on film band proper the invention can also be put into practice in such manner that the picture series of the standard talking lm band is projected on the scanning field of the television decomposer in an optical way by means of a con- CFI the special case, projected on a Nipkow disk having spiral circles of holes, and which operates in the known manner. Hence due to the superposition of the individual pictures on the disk without interruption or gaps, a forced ratio of reduction between the disk and the transport movement of the iilm is not required; the Nipkow disk on the contrary may be driven, entirely independent, with that number of revolutions corresponding with the desired increased n of the optical scanning.

A third possibility for carrying out the invention is obtained by the use of the so-called Braun or cathode ray tube as picture scanner. This application has been proposed already in various instances. It consists in moving the point of light on the fluorescent screen of the tube in the sense of the decomposition of the picture whereby it can be sharply projected through a lens on to the iilm to be transmitted. A photoelectric cell disposed in back thereof receives in accordance with the distribution of the black portions in the picture of the lm a greater or smaller amount of light. Since a continuous advance of the picture band automatically furnishes the cross component of the television decomposition in this arrangement the point of light can be limited to its movement within always the same trace of lines. This type of scanning, as is known, can be accomplished in the cathode ray tube by means of relaxation oscillation deviating the electron beam at constant velocity along the picture line in order to cause it to suddently return to the starting point at the end of the line.

In order to carry out the invention by means of such cathode ray scanner, in addition to the before described operating performance, an electrically cr magnetically effected periodical lateral displacement of the course of the picture points is carried out at right angle to the line. This displacement is transmitted to the picture film by means of the projector lens. The resultant rhythmic movement of the cross line is against the movement of the film operating at standard speed, until under the influence of the second relaxation oscillation by which it is controlled, it suddently jumps back into the starting point. Then it begins anew.

This type of performance is schematically shown in Figure l of the drawing wherein there is indicated eight diierent phases I-VIII of the displacement of the nlm band shown in cross seotion, whose individual lengths of the pictures is shown by the section l, 2, 3, etc. The lm moves in a continuous fashion and not in sudden steps, in the direction of the arrows 3. Against this film there moves the location of the scanning line in the sense of arrow Il; however the same jumps back over an entire width of the picture within regular time intervals corresponding with the phases II, V, VIII (arrow 9). While the lm in the example chosen (nzi, 1L=24) advances at 2,5 of its standard width of the picture, the scanning movement of the cross line of the point of light'moves towards the film at 1/3 of the width of the picture. After an advance of the nlm of 2 times 2,@:9 normal picture widths, the course of thev point of light hence has continuously passed over and scanned in lines 3 full pictures, as seen from Figure l. If therefore the band of the talking film is moved at a standard speed u'=24 picture Widths per second, the light point decomposes in this line 24 times iQ-:36 pictures. The dotted line represents the displacement as to time of the scanning line, and hence also the shape of the voltage of the relaxation oscillation necessary for the cathode ray deviation. In the intervals 1 1', `I'-", 7"-1" the snapping back of the cathode ray, i. e., the relaxation of the voltage at the important pair of deviation plates, takes place.

An example of one suitable arrangement for carrying out this control is shown in Figure 2. The film I is continuously moved and thereon the line 2 of the light point of the cathode ray tube of which only the end surfaces of the bulb I3 is indicated, is correspondingly reduced and sharply reproduced by means of the lens l. The incident light is passed to the photoelectric cell 9 by means of lens 8. The plate pair serving for the line deviation of the light point is not shown in the drawing. At 90 displace thereto, there is provided a second plate pair 3, for the required cross displacement in the sense of the invention, cf the scanning line 2 on the screen of tube I3, or on the nlm I respectively. This plate pair 3 is in parallel to the condenser' 4, which can be periodically charged by a. direct voltage source across a resistance E. The entire arrangement conforms with an ordinary relaxation circuit, and hence all means known in such arrangements for obtaining a definitely shaped charging current curve, can be applied, for instance, in place of an ehmic resistance ti, an electron tube operating in the region of saturation, or better a pentode can be used whose anode current remains constant within a wide interval of the plate potential. For the discharge of the condenser 4 or the plate pair 3 respectively, a controlled discharge tube I2 serves, for instance, a glow relay or thyratron, whose grid is positively charged by a periodically operated switch II which is controlled by the movement of the nlm. To this end the film is passed over rollers Iii, with which the switching device II is coupled in a forced manner in the proper ratio oi reduction. In this manner the cross movement of the line of the cathode ray, shown in Figure l, can be easily and simply controlled practically without energy, and thus the desired compensation of the picture can be 0btained.

The relaxation oscillation required for the compensation of the pictures and produced according to the method in Figure 2, may be used at the same time for the synchronization of the cross deviation of the electron beam in the picture receiver. Hereby it is necessary to transform upwards the relaxation frequency in the proportion 1h, since according to Figure 1 there corresponds with the interval between the individual relaxation performances, the threefold transmission of the picture iield. This frequency ratio is not required to be carried out in the receiver, it can be produced already in the transmitter by means known as such.

The invention is, of course, capable of modication and I, therefore, believe myself to bc entitled to make and use any and all modifications thereof which fall fairly within the spirit and scope of the hereinafter appended claims.

What I claim and desire to protect by Letters Patent is:

l. In television apparatus, a. motion picture lm of which the electro-optical image reproduction of each lm frame area is to be produced at a distance point, means for moving the lm at a preestablished constant speed past a point of analysis, a. cathode ray tube having means therein to produce a point source of light of elemental area, an optical system to direct the light produced Within the cathode ray tube upon the nlm to illuminate an area of proportional size on the nlm, and a light translating device for producing when illuminated in accordance with the varying densities of the nlm record as illuminated by the cathode ray spot varying electrical energy output corresponding to the nlm density at the elemental area instantaneously illuminated, denecting means associated with the cat-hode ray tube for causing the cathode ray beam developed to scan thenlm transversely in a line for line manner during the nlm motion past the predetermined point vand a second denecting means for causingthe line for line scanning of the nlm frame areas passing before the predetermined point to be of a different number than the lines of elemental Width oi' the nlm actually passing the said predetermined point Within the said predetermined time period.

2. In television apparatus, a `motion picture nlm record of which the electro-optical image reproduction of the successive nlm frame areas thereof is to be produced, means for continuously moving the nlm past a predetermined point at` a pre-established constant rate corresponding to the rate of nlm motion suitable for the translation of the sound record accompanying the nlm frame areas into electrical signaling impulses, a cathode ray tube having means therein to develop a point source of light for illuminatingan area of elemental size on the nlm record, a light translating device arranged to receive light corresponding to the varying densities of the nlm record as illuminated by the cathode ray light spot .impinging thereon, means for causingthe cathode ray light spot to traverse the nlm frame areas in a direction transverse to the direction of nlm motion at a predetermined rate so that each nlm frame area is illuminated with a series of sub- 'stantiallyparallel paths of light of equal number,

and means for causing the illuminated cathode ray spot to scan a dinerent number of equall length transverse paths across the nlm than the number of such paths of elemental width which pass the predetermined point within a predetermined time period. k

3. A system for scanning nlm for the television transmission of electro-optical reproductions of the independent nlm frame areas which comprises means for moving the nlm continuously past a predetermined point at a predetermined. pre-established constant rate corresponding substantially to the rate at which the sound recordings on the nlm are to be translated into electrical signaling impulses, a cathode ray tube for producing a spot of light for illuminating the nlm along a series of paths each of elemental width ,transverse to the direction of motion of the nlm, and means for causing the cathode ray spot to be displaced'in a second direction at right angles to that along which the nlm is illuminated so that a different number of nlm frames may be exposed to an identical number of transverse paths of light in a predetermined timeperiod than the number of nhn frames which pass the predetermined point in the same time period.

4. The method of producing televisionimages from a motion picture nlm record which includes the steps of `moving the nlm record continuously at a pre-established constant rate past a prej determined plane of analysis, developing an elecy f tron beam within an electron tube and converting the produced beam into a point source of light of elementalsize to illuminatean elemental area of proportional sizeon the nlm record, translating the light values on the illuminated elemental nlm areasy into electrical energy of amplitude varying in accordance with the densitiesy of the elemental areas of the nlm record illuminated, tracing the developed light spot across the nlm -record in a path transverse to the nlm motion so as to scan the same along a path transverse to the path of nlm motion past the predetermined plane denecting the produced electron beam simultaneously in a direction normal to the plane of the transverse light path traces and controlling the last named denection in accordance with the nlm motion to return the beam at predetermined time periods to a plane of initial transverse denection so that a different number of transverse light traces of the nlm are made during a predetermined time period than the actual number of transverse paths of the same Width which pass the said predetermined plane of analysis With the nxed predetermined time period.

5. The method of producing-television from a motion picture nlm record continuously which comprises moving the nlm record at a pre-established constant speed past a point of analysis, developing a cathode ray beam to produce a point source of light of elemental area on the nlm, pro- Aducing electrical impulses of variable amplitude proportional to the varying shade densities on the elemental areas oi the nlm record as illuminated by the cathode ray beam, continuously denecting the cathode ray beam in a plane transverse to the nlm motipn to scan the nlm transversely in a line for line manner during the nlm motion past the predetermined point, then denecting the developed beam in a second direction normal to the plane of the nrstdenection simultaneously with the nlm motion, and controlling the cycle of the second named deflection in accordance with the nlm motion to return the beam to an initial plane of transverse denection at predetermined time intervals for causing the line for line scanning' of the nlm frame areaspassing before the predetermined point to be of a dinerent number than the lines of elemental Width of the nlm actually passing the said predetermined point Within the said predetermined time period.

6. In television apparatus, a motion picture nlm of which the electro-optical image reproduction of each nlm frame area yis to be produced at a distance point, means for moving the nlm at a pre-established constant speed past a point of analysis, a cathode ray tube having means therein to produce a point source of light of elemental area, an optical system to direct the light produced within the cathode ray tube upon the nlm to illuminate an area of proportional size on the nlm, and a light translating device for producing when illuminated in accordance with the Varying densities of the nlm record as illuminated by the cathode ray spot varying electrical energy output corresponding to the nlmdensity at the elemental area instantaneously illuminated, denecting means associated with the cathode ray tube for causing the cathode ray beam developed to scan the nlm transversely in a line for line manner during the nlm motion past the predetermined point and a second denecting means for `causing the line for line scanning of the nlm frame areas passing before the predetermined y FRITZ SCHRTER.

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