Radio mirror (Jan-Oct 1923)

Mav «$, /<.»-'•; RADIO DIGEST MOVIES IN THE HOME BY RADIO "SOON WILL BE PROVEN FACT," SAYS INVENTOR Inventor of "Pictures by Radio" Machine Working Out Problem Only One Kink Unsolved Will Enable Persons in Far Away States to See Inaugural Ceremonies By L. M. Lamm "Movies by Radio in the home will soon be an accomplished fact, startling as this mav seem, for the only unsolved problem is the speed factor," says C. Francis Jenkins of Washington, D. C, inventor of a machine by which photographs are sent by Radio. Actual demonstrations have been made between Washington and Philadelphia of the practicability of sending these pictures and Mr. Jenkins is now working on perfections of his new idea. Answering the writer's questions, Mr. Jenkins continued: "When, then, this remaining: problem of speed is solved, and it is now being worked out gratifyingly, persons in California or Nebraska or Maine or Florida will be able to see the inaugural ceremonies of their President in the National Capitol on the day of inauguration, or both see and hear grand opera broadcast from any point. Will Allow Past Picture Distribution "Meantime, while this problem is being worked out photographs by Radio will be perfected for useful and speedy service in the distribution of picture news for the daily paper, the news bulletin, the theater and all other subscribers to such service." The process of broadcasting photographs, Mr. Jenkins explained, consists chiefly in "slicing" the picture to be broadcast into hundreds of perpendicular sections, each about 100th of an inch thick, and in moving the projected image of each section across a so-called photo-electric cell, made of selenium or a similar mineral, whose ability to carry an electric current varies with the intensity of light falling upon it. As each section of the illuminated image is thus drawn across the cell, the dark portions, halftones and light spots formed along the "slice" by the shadows, lights and color variations by the photograph serve to correspondingly decrease, increase or maintain the flow of electric current through the cell. Substitute for Microphone Having transformed light variations into electric current, Mr. Jenkins explained, it was a simple matter to substitute t"his instrument for the microphone mouthpiece of the Radiophone, for the function of the microphone is similar to transform sound variations into current variations. To reproduce the picture at the receiving station a virtual reversal of the sending process occurs. Two methods have been successfully employed. By the first method, the Radio waves are received over a regular Radio receiving set, the receiver of which, however, is equipped as follows: On the metal diaphragm of the receiver is mounted a tiny mirror which vibrates with the diaphragm as the Radio oscillations are registered. Focused on the mirror is a strong ray of light, which is re-i fleeted through a shutter when the mirror is stationary. As the impulses originating from the sending station start, the mirror oscillates with the diaphragm and the reflected ray also oscillates across the shutter hole. Thus, when the diaphragm is vibrating slowly more light from the ray filters through the aperture than when the vibrations are rapid. The current variations received by Radio are accordingly transformed back to light variations which are registered on a sensitized photographic plate. Receiver Has "Slicing" machine Also It will be seen, however, that these variations as they are received must be reproduced in perpendicular "slices" across the face of the plate in order to build up again the completed picture. Here Mr. Jenkins devised a new type of disc prism, which he has patented, constituting in appearance a circular glass plate, about ten inches in diameter, with a rim beveled to form a prism of spiral shape and of gradually increasing thickness at the edge. As the beam of light from the mirror strikes this revolving prism it is bent along a perpendicular path downward across the plate, repeating this movement At the left is shown the wonderful complicated mechanism by which pictures are sent through the ether. The four discs are the "Slicer Prisms" and the small driving motor is to the right. Above in circle is C. Francis Jenkins, the inventor until each section of the original picture, sliced up in a similar way by circular prisms, has been neatly laid down beside its neighbor to form the completed reproduction. The correct horizontal spacing is maintained by a system of like discs, revolving in the sending and re^ ceiving stations at the same speed. Second System Simpler The second method, just recently developed and the one which, because of its simplicity, probably will be permanently substituted for the former system, consists in sending the Radio current as amplified by the Radio receiving outfit through a specially constructed incandescent electric light bulb, the tiny filament of which is surrounded with hydrogen. About two volts of a storage battery current are conveyed constantly through this filament, so as to produce a red glow in the bulb. As the varying Radio currents course through, the filament lights up, dies down to produce half tones, and shades. Thus it reflects directly on the plate the varying intensities of light. This method does away with the uncertainty of reflecting mirrors, which are always subject to vibrations likely to distort the reproduction. Needs Little New Apparatus It is evident, therefore, that little apparatus is required, in addition to standard Radio equipment, to make the usual receiving set a picture-receiving outfit. The entire adjunct takes up but a small ADJUSTABLE COIL MOUNTINGS FOR FLEWELLING CIRCUIT Triple Coil Mounting $5.00 List Double Coil Mountings 3.50 List A patented feature locks the coil in place and prevents the coil from being thrown out of adj usttnen t once station is tuned in. Licensed under U. S. De Forest Pat. 1365170 Dealers write for special discounts ASTORLOID MFG. CO., SUilM TWO SUPERSENSITIVE CIRCUITS (Both Copyrighted) My Highly Improved Reinartz brings In all important stations on both coasts and Mexican border, loud, clear and without distortion. We dance to music from Atlanta, received on one loud Baldwin unit. Build one of these wonderful sets from my blueprints and specifications, price 50c, or with a perfect and complete double wound spiderweb coll. S3. 00 by mail. No other windings used. Photo of my set on a glass panel with every order. This copyrighted circuit is the most successful of any Reinartz modification yet produced, and is imitated the most. Thousands are in use. My W. D. f I Circuit is especially designed for use with the "Pickle" tube and brings out the full value of that little tube as no other circuit can. Stations 1000 miles away come in clearly on one tube. This set is small, complete, portable. For the man who wishes the highest efficiency, this is the set to build. Price of blueprint and specifications, 50c, or with complete and perfect windings. $3.00. Photo of set with every order. Either set is easy to build, easy to operate. Everything clearly shown. These high quality silk insulated coils are machine wound on fiber forms. I wind coils to your specifications in lots of 100 or more. Write for prices. S. A. TWITCHELL 192S Western Ave. Minneapolis. Minn. amount of room and can easily be placed on the library table for operation. A person of constructive inclinations could readily manufacture his own set, providing, of course, he could obtain possession of the disc prisms. Heretofore, inventors have succeeded in sending etchings by Radio by curving the etchings over a revolving cylinder and passing slowly across the cylinder an electrical contact, which sent out current impulses as it touched the high points of the etching. Never before, Mr. Jenkins says, have photographs themselves been transmitted because of the inability in times past to reproduce halftones. The first distant transmission of photographs by Radio was made by Mr. Jenkins on March 3 when they were sent from the naval Radio station in this city to the receiving station of the Philadelphia Evening Bulletin. The test was made under the auspices of the North American Newspaper Alliance in the presence of newspaper publishers and scientists. At that time pictures of President Harding, Vice President Colidge, and Governor Pinchot of Pennsylvania were sent and received very successfully. It is written : "A single conversation across the table with a wise man is better than ten years' mere study of books." The wise man owns a Grebe Receiver — seek his advice and profit by his judgment. Write for 'Musings of Dr. Mu" 9^ Licensed under ' Armstrong U. S. Pat. No. 1113149 A. H. GREBE & CO., Inc. Richmond Hill, N. Y. Western Branch— 451 East 3rd St., Los Angeles, Cal.