US2168048A - Electro-optical system - Google Patents

Description

vAug. l, 1939. A. M. SKELLETT ELECTED-OPTICAL SYSTEM Filed Dec; 24, 1956 ATTORNEY Patented Aug. 1.1939

'Bell Telephone Laboratories,

Incorporated,

New York, N. Y.,- a corporation of New York Application December 24, 1936, Serial No. 117,522

g 10 Claims.

This invention relates to electro-optical systems and more particularly to the electrographic ing images from currents produced by moving a stylus over the subject along selected paths such as the boundary lines between areas of distinctlve tone values. The frequency band required for' the transmission of these images is small compared with the band required in ordinary television systems. The present invention is directed to the improvement of'apparatus of the electrograph type for transmiting animated images and particularly to an improved apparatus for transcribing the movements of a stylus along the boundaries of distinctive areas of the subject into tracks on a film or other record member for use particularly with animated carto'ons or similar sketches.

It is another object of this invention to provide an improved transcribing device for animated subjects. r

It is a further object of this invention to providea novel transparent template to assist in tracing the background of the subject field.

In accordance with one embodiment of this invention, shown for purposes of. illustration and hereinafter described in detail, the images of individual, frames of an animated film are projected upon a ground glass screen The boundaries of distinctive areas of the image figure on the screen are then traced by a stylus and as the stylus moves around in the field two cables attached to it open two slits in a light valve in proportion to the rectangular coordinates of its successive positions with respect to a pairof oo- The dimension of the track along the film represents the length of time taken to trace a particular portion of the image and may be used tocontrol variations in density of the received image.*- A transparent template with a continuous groove tofit over and coincide with the background may be. mounted so as-to be quickly swung in position on the ground glass and, with ,itthe background-may be transcribed at a speed greater than that of the central figure. As soon as one frame is transcribed, another frame is shifted into place in the projector and the transcribing process repeated. For reproducing or converting the tracks on the film into signal currents, the images of the tracks on the film are projeced upon two photocells. These cells may be connected respectively through'amplifiers to the two pairs of deflecting plates of a cathode ray receiver.

The invention will be' more readily understood by referring to the following description, taken in connection with the accompanying drawing forming a part thereof in which:

Fig. 1 is a schematic diagram of an electrographic systemembodying this invention;

Fig. 2 is a perspective view of the transcriber;

Fig. 3 is a top view of a transparent template used in the arrangement of Fig. 2;

Fig. 4 is a cross-sectional view of the template of Fig. 3; and p Fig. 5 'is an enlarged diagrammatic'showing of. the optical system of Fig. 2. v

Referring more particularly to the drawing, Fig. 1 shows schematically an electrograph sys- .tem embodying this invention. In this figure sketches III, which may be views of the same After proper development and, if 'desired,'

fixing, the film I2 is passed into a device I6 which is called a converter. If desired there may be a time interval between the transcribing and converting operations. In other" words, the tracks l4 and'l5 on the film 12 may be made well in,

advance of the time the program is transmitted or broadcast; In the converter IS, the tracks on the film are used to generate signal currents which are transmitted to a receiving station which preferably includes a cathode ray device I I. The converter preferably comprises a pair of photocells actuated by the images of the tracks I4 and IS on the film ii to produce varying signal currents respectively proportional to the suc-' cessive positions of the stylus with respect to the pair of coordinate axes. Fora more complete description .of a converting device somewhat similar to the device l6, reference may be made to the above-mentioned Skellett application.

The signal currents generated by the photoelectric cells in the converter It may then be used to modulate carrier waves generated by suitable oscillators (not shown) and these modulated carrier waves are transmitted over respective channels l8 and [9, which may be either line or radio channels, to the receiving station R. Suitable amplifying devices 20 and 2| may be used at the transmitting station and amplifying devices 22 and 23 at the receiving station to produce greatly amplified signals.

The signals in channels l8 and I9 are then applied to two pairs of deflecting plates 24 and 25 of the cathode ray receiving tube l'l. Cathode ray tube I1 comprises suitable means (not shown) for producing a beam of electrons and for accelerating this beam towards a fluorescent screen 26. The voltages from the channels |8and l9, respectively proportional to the'signal currents generated at the transmitting station, create electrostatic fields between the members of pairs of deflecting plates 24 and 25 respectively which deflect the beam to positions corresponding to the changing locations of the stylus at the transmitting station. If desired, means may be provided for generating a signal when the stylus is lifted from the surface of the representation (as when it is moved from one boundary to another) and this signal used to cut off the cathode ray beam .of the tube I'I during this interval of time. For a description of apparatus for producingthis signal together with a morecomplete description of the system shown in Fig. 1 on the right of the transcribing device I l, reference may be made to the above-mentioned Skellett application. If desired, the stylus may be moved quickly from one boundary to another and this will show on the image at the receiving station only as a faint trace.

The improved transcribing device of this invention for making tracks on film corresponding to the successive positions of the stylus with respect to a pair of coordinate axes is shown in Fig. 2, the arrangement being particularly applicable to animated cartoons or similar subjects. In this arrangement, a projecting apparatus 30 is arranged to project upon a ground glass screen 3 I,

one frame at a time, the images of the frames of a motion picture film which may be, for example, of the type generally known as animated cartoons. A stylus 32 traces boundaries of the distinctive areas of the image 33, preferably in a continuous line, and the motions of the stylus 32 operate the opening and closing of a double light valve 34 by means of appropriate cables 35 and 36 passing over reels 31 and 38 and attached to moving slide members 39 and 40. The slide members 39 and 40, acting against the pressure of springs 4| and 42, control the size of the slits 44 in accordance with the position of the stylus with respect to its coordinate axes. -A- point 0 represents the intersection of the X and Y axes. A table or other supporting device 53 supports the screen 3| and it maybe provided with arms 54 and 55 to support the reels 31 and 38.

Light from a suitable elongated source 45 is focused byany suitable device, such as a cylindrical lens 46, upon or near the plane of slits' 44, and the image of these slitsis formed on film I 2 by means of suitable lenses 4! and 48 to produce variable widthimage tracks l4 and I5 The film I2 is adapted to move continuously in the direction of the arrow by means of suitable rollers 49, 50, 5| and 52. If it is desired to make all the boundaries of the same density, the stylus is moved along theboundaries at a uniform rate of speed. Shading can be accomplished by varying this rate ofspeed. After the film l2 has been developed, fixed and dried in accordance with well-known photographic technique, the tracks on the film may be used to generate the signal currentsfor transmission to the receiving station as stated above in connection with Fig. 1.

' It is estimated that a skilled operator will spend no more time in transcribing the drawing than was required by the artist in drawing it originally. As there are time-saving tricks peculiar to-the art of producing animated cartoons so there are also such artifices peculiar to this transcription technique which will save time and labor considerably. When one frame has been completely traced, the next frame is imaged by means of the projector 30 upon the ground glass screen 3| and this image traced by the stylus as described above.

When the image of every frame has been traced by the stylus, the film I2 will comprise a coordinate track record of the entire moving picture film used in the projector 30. Regardless of the time taken to transcribe the images on a film from the projector 30 into tracks on the film I2, the film I2 is run past the photoelectric cells in the converter device l6 at a speed such that a continuous animated image .is produced on the fluorescent screen 26 of the cathode ray tube I1 at the receiving station. For example, film l2 may be run through the converter at a speed such that twenty-four complete frames are produced per second in the cathode ray tube l1. Since this period of time is within the period of persistence of vision, the image on the screen 26 will move without flicker effect.

Various changes may be made in the transcribing device of Fig- 2. The stylus may be coupled to the light valve by any other suitable means, either mechanical or electrical.- As an example of an electrical method for coupling the movement of-the stylus in the light valve, refercation. The film I2 may be replaced by any other record member,v such as for example magnetic tape, or a sound record on wax or metal. If any of these other record members are used, the associated recording apparatus would be used in place of the light valve 34.

Frequently in transcribing animated cartoons, the background remains the same for a considerable number of pictures. The transcribing of the background may be simplified by the use of a suitable device such as the transparent template disclosed in Figs. 3 and 4. This template 60 comprisesa flat plate having a continuous groove 6| cut therein in the shape of the background. The stylus 32 is adapted to move in this groove and hence the background may be quickly and easily transcribed. The density of the background line on the fluorescent screen 26 may be controlled by I than those of the ordinary high fidelity radio aice'p-is' 5 the speed at which the stylusismoved in the groove ii. If it is traced quickly the line will be light whereas if the stylus is moved at a slower rate of speed, the background line will be relatively dark. As explained above, thissame general principle applies to the figureas well as to the background. A transcriber artist may use this principle to produce shaded images.

\ The frequency band width'required by the system of this invention is relatively small compared with that required in ordinary television systems. It is inherent in well known systems in television that high definition must at all times be realized no matter how simple the transmitted image may be. Many useful and entertaining images, however, do not contain a great amount of detail and in transmitting them large blank areas on the,-

available field are wastefully transmitted. The animated cartoon is an example of such a simple image. In this invention, the figure and line background without the blank areas is transmitted and thus a great simplification occurs, which simplification is expressed in the'lowering of the frequency band required for transmission to a width sufiicient so'that it may be used with carriers of the ordinary broadcast frequency range. The required band widths are no larger transmitting stations of today.

Various modifications may be made in the invention as above disclosed, the scope of which is indicated by the appended claims. In the claims, the expression "boundaries of areas of distinctive tone values is intended to be inclusive of the case where an area of distinctive tone value is a line as in an outline sketch or drawing. The two parallel boundaries'of a line area are for practical purposes coincident, so that a stylus tracing the line is in effect tracing each boundary of the line area; that is, tracing both boundaries of the line area simultaneously.

What is claimed is:

l. A method of image production comprising the steps of projecting successive still images of a subject upon a screen, each image differing from its immediately preceding image to an extent corresponding to a time interval within the period of persistence of vision, tracing the boundaries of 1 areas of distinctive tone values of said images, generating two potentials continuously varying in accordancewith the positions of the successively traced elements of said boundaries with respect to the axes of a coordinate system, recordingsaid potentials, and producing electric signal currents in accordance with said recorded potentials at a rate of speed different from that at which said potentials were recorded.

2. A method for making a coordinate recordmember corresponding to successive images of an animated subject which comprises projecting successive images of the subject upon a screen, each image diifering from its immediately preceding image to an extent corresponding to a time interval within the period of persistence of vision, tracing the boundaries of areas of distinctive tone values of each image on the screen, and utilizing the positions of the successively traced elements of said boundaries with. respect to a pair of coordinate axes to produce a record inember of said positions. I

- 3. A system of image production for animated subjects comprising a screen, means for projectingasuccession of still images of the subject on said screen, each image differing from its immediately preceding image to an extent correspond- 3 mg to a-time' interval within theperiod or aries of areas of'distlnctive tone values of each image in succession, and means for recording as tracks one record member the movement of said styluswith respect to a pair of coordinate axes.

4.;A system of image production for animated subjects comprising a screen, means for successively projecting still images oflthe subject on said screen, each image differing from its immediately preceding image to an extent corresponding to a time interval within the period of per- 'sistence of vision, a stylus for tracing the bound- P sistence of' vision, a stylusfor tracing the boundaxles of areas of distinctive tone values of each image in succession, a light source, a moving film, and a pair of light apertures located between-sald light source and said film, the widths of which are respectively controlled by the movement of said stylus with respect to coordinate axes perpendicular to each other, whereby there is recorded on said film tracks corresponding respectivelyito" the successive positions of the stylus with respect to said system of coordinates 4 r 5-. In combination, a motion picture film rec- 0rd of an animated subject, a screen, means for projecting, a frame at a time, images of said animated subject upon said screen, each frame image diifering from its immediately preceding frame image to an extent corresponding to a time interval within the period of persistence of vision, means for tracing witha stylus the boundareas of' distinctive tone values of each of said images, and means for making a record member of the movements of said tracing means with respect to a system of coordinates.

7. An electrograph system comprising a. transparent screen, means for projecting a series of images of an animated subject on, one side of said screen, each of said images differing from its immediately preceding image in the series to an extent corresponding to a time interval within the persistence of vision and each image comprising a background which is substantially the same as the background in the other images in the series, a transparent template having a continuous groove therein which fits over and coincides with the background in each of said images, said transparent template being placed on the side of said screen remote from the side upon which the images are projected, a stylus, and means for mounting said stylus so that it may be quickly moved'in said groove.

8. A'system of image production for animated .subjectscomprising means for successively projecting an image of each frame of a film record of an animated subject upon a screen, each frame image differing from .its immediately preceding frame image to an extent corresponding to a time interval within the period of persistence of vision, stylus controlled means for resolving the image of each frame into two signal currents rescreen, a supporting member for said screen,

means for successively projecting an image of each frame of a film record of an animated subject upon said screen, each frame image differing from its immediately preceding frame image to an extent corresponding to a time interval within the period of persistence of vision, a stylus for tracing the boundaries of areas of distinctive tone values of'each frame image, a light valve having two apertures therein, means controlled by the movement of said stylus for de-,

termining the width of said apertures, a light source, means for focusing the light from said light source upon said apertures, a moving film, and means for focusing the light passing through said apertures upon said moving film to make tracks thereon corresponding respectively to the successive positions of said stylus with respect to a pair of coordinate axes. 1

10. In combination, a supporting member, said supporting member having a transparent portion therein, said transparent portion being arranged to have projected thereon a succession of still images, each image differing from its immediately preceding image to an extent corresponding to a time interval within the period of persistence of vision, an elongated plate member having two elongated slits therein, an elongated light source, means for focussing radiations from said elongated light source upon said elongated slits, a stylus, means for supporting said stylus so that as it moves over boundaries of areas of distinctive tone values of an image on said transparent portions of said supporting member portions of said elongated slits are covered so that light from said source does not reach said slits, and a record member for receivingthe light which passes through the parts of said elongated slits which are not obscured, whereby a record is made of the coordinates of the successive positions of said moving stylus with'respect to a pair of coordinate axes in a time interval much greater than one within the period of persistence of vision.

ALBERT M. SKEILE'I'I;

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