US1724684A - Picture telegraphy - Google Patents

Description

Aug. 13, 1929. o. SCHRIYEVER 1,724,634

PI CTURE TELEGRAPHY Filed Sept. 28, 1927 MA /mt INVENTOR mo scmusvm RNEY Patented Aug. 13, 1929.

UNITED STATES PATENT OFFICE.

OTTO SCHRIEVER, OF BERLIN, GERMANY, ASSIGNOR TO GESELLSCHAFT-FUR DRAHT- LOSE TELEGBAPI-IIE M. B. H. HALLESCHES, F BERLIN, GERMANY, A CORPORA- 'IION OF GERMANY.

PICTURE TELEGRAPHY.

Application filed September 28, 1927, Serial No. 222,510, and in Germany October 15, 19.26.

Contiguity of the constituent points of a picture, as is well known, is changed in pieture telegraph into a time sequence by whatis known as tie exploration or analysis of the picture. The means most commonly known for this purpose consists of spirally moved and synchronously revolving cylinders, one of which at the sending end carr-ies the picture. to be'transmitted, while the other one at the receiving end carries the recording paper-or film of a nature Varying with the particular system used.

This method of exploration involves a number of drawbacks. In the first place, after a given transmission has been completed, the cylinders or drums must be stopped to change the picture with the result that a certain amount of time islost between two pictures. Another fact is that the drums must be built guite rugged in order that they may not su er any mechanical deformation due to the often repeated exchange of the pictures, and this necessitates a rather large volume of energy for synchronizing purposes. The necessity of constant change of a certain amount 0 inconvenience in manipulating and using the apparatus.

For this reason, various attempts have been made to replace the cylinder .or drum system by a system which permits a continuous sequence of pictures, for instance, by that at the sending end the pictures are continuously moved past the exploring means by the aid of a conveyor band, while at the receiving station the pictures are reproduced upon a recording tape continuously paid out from a roll. However, suggestions in this direction are'in lack of a 40 practically useful exploring method.

. It is, therefore, an object of the present invention to provide a method and means for overcoming the above named difficulties.

Other ob'ects of the invention are to proicture finally involves To now make reference to the drawing forming a part of this specification, the invention consists essentially of an optical ex I eopiedby' lens system L in the plane E of vide a met 0d and means for carrying out' the objects above set forth which is simple in its construction and arrangement of parts,

simple, compact, durable, eflicient in use and inexpensive to install.

Still other objects will become apparent upon a reading of the specification .and claims in connection with the accompanying drawing, which diagrammatically illustrates one form which the invention may assume.

the picture (a b). The light source is dis-, posed 1n the rear of a moving screen, for instance, in the inner space of an'opaque hollow cylinder having a spiral slit S and in a position parallel to its axis, in'which latter case the slit is so formed that it will intersect once with the generatrix of the cylindrical surface at any given point. If, then,

the cylinder is set in rotation, only a small point of the light source will be ex 'osed, and its image or copy, being ofthe size of a picture element, passes at the place a I) constantly across the picture, and always 1n one'and the same direction. If the pic ture or the recordin tape is continuously shifted in its longitudinal direction, i. -e., at

right anglesrelative too I), it will be seen that the luminous spot will describe upon E a family of arallel exploring lines. vAt the sending en a photo-electric cell is dis posed 1n such a way that it will either respond to the light more or less intensely reflected from the picture strip, or else to light allowed to penetrate through the picture strip in varying volumes. At the re- .oelving end, fundamenta-ll speaking, any convenient kind of light relay or valve may be used. Particularly useful in this connection is, for example, a slit-shaped glowdischarge lamp or Kerr cell. The slitshape of the light source ma be improved upon both at the sending an at the receiving end b the aid of a slit screen mounted at small istance from the cylinder wall at the inside or the outside.

-The apparatus herein disclosed becomes especially simple as regards its optical means if the picture strip is made comparatively narrow, say, of the width of a Morse telegraph tape. This allows of continuous high speed telegraph operation in which signs of any desired kind may be used. I

To increase the speed of exploration, a plurality of spiral screens may be arranged upon the drum.

The arrangement hereinbefore described allows of using at point L a sufliciently cor rected objective in order that the image of.

the light source may be produced in the picture place without any optical distortion.

Having now described my invention, I

5 am entitled to all modifications thereof that '10 which include a rotary drum, an elongated thread-like filament within said drum a .spiral slot extending about the periphery and longitudinally of said drum through which said light is adapted to be projected at different points durin the rotation of said drum, a lens system %0 light, a picture strip adapted to have its surface. scanned transversely by a point of light from said lens system, and means re- 15 r directing said sponsive to variations in light intensity 20 passing through said picture strip for producmg a variation in current impulses.

OTTO SCHRIEVER.

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