US1689666A - Method of transmitting pictures and sending plate therefor - Google Patents

Description

M FERREE ET AL METHOD OF TRANSMITTING PICTURES AND SENDING PLATE THEREFOR.

'2 Sheets-Sheet 1,.

Filed Jar 1. 28, 1925 M. FERREE ETAL METHOD OF TRANSMITTING PICTURES AND SENDING PLATE THEREFOR Filed Jan. 28, 1925 2 Sheets-Sheet 2 Patented Oct. 30, 1928.

UNITED STATES 1,689,666 PATENT OFFICE.

'MAEVIN FERREE, or NEw YORK, N. Y., AND JOSEPH wrssm. or CLEVELAND, OHiO, ASSIGNORS, By :omEcT AND MES NE ASSIGNMENTS, To PICTURE TRANSMISSION CORPORATION, on NEW YORK, N. Y., A CORPORATION OEDELAWLRE. j

METHOD or TRANSMITTING rIcTUB sA n SENDING PLATE TiIEEEEon.

Application filed January 28, 1925. Serial No. 5,258.

One of the objects of this invention is toprovide a methodof transmitting pictures by means of a series of electric pulses where by those portions of the picture which correspond to the intermediate or gray portions thereof shall be sufiiciently emphasized so that the reproduced picture will properly correspond to-the original picture.

Another object of this invention is to devise a method of transmitting pictures by means of a series of electric pulses whereby the electric pulses, or the intervals between electric pulses will be extremely long when the gray or intermediate (portions of the picture are being transmitte Another object of this invention is to devise a new and improved broken tone transmitting plate of the picture to be transmitted in which the picture consists of a series of separated and parallel lines of varying thickness, and in which said plate will be free from these'parallel lines in those por tions of Said plate corresponding to the intermediate or gray portions of the picture to be reproduced.

Other objects of this invention will be set forth in the following description and drawings, it being understood that the abovegeneral statement of the objects of this invention is intended, not to limit the invention, but to generally explain the purposes thereof.

Fig. 1 shows a transmitting plate of a picture to be reproduced, made according to the old method. I

Fig. 2lshows a plate made according to this new and improved method and to be p v used in transmitting pictures according to the new and improved method.

It has been previously suggested to use a broken tone plate of the picture to be transmitted, in order to transmit the said picture by means of a series of electric ulses and this, for exam le is shown in U. Patent No; 577,373, lssued on-Feb. 16 1897,

' to Noah S. Amstu'tz, and in U. S. Patent No.11,026,297, issued on May 14, 1912, to Thgmas Thorne Baker. In the methods prev'iously used, the half tone plates embe employe ployed for controlling the series of electric pulses were made as shown in Fig. 1 and by the ordinary method employed in making half tones so that the entire picture was broken up into separated areas save where the natural composition or color efli'ect of the picture to be transmitted caused the transmitting plate to have solid white or black areas. If, however, the composition of the picture to be transmitted was such thatit was composed throughout of intermediate or gray tones of varying intensity, then the entire transmitting plate was broken up as illustrated in Figr- LK According to this invention, the transmitting plate, which ispreferably a negative, is produeced by being exposed in such manner that the lighter tones of the pi ure and particularly the background thereo are ac-. centuated so that corresponding solid dark masses are produced in the same negative, as illustrated in Fig. .2.

The picture to be reproduced is first placed in front of sin ordinary camera so that a negative can be made thereof. This negative is made upon an ordinary transparent glass plate, either wet or dry.

fore the negative impression is made, a

transparent grating having a series of parallel opaque lines is placed in the camera before the negative, so that the negative image consists of a series of parallel opaque lines of varying width, and the continuous tone of the picture to be 'transmittedis thus duplicated in what may be called broken tone.

The spacing of theopque lines may vary, and without being limited to any particular spacing, it has been found that a grating I having sixty-five (65) lines to the. inch is satisfactory for reproducing ordinary photographs. The width of the said opaque lines may be equal to the distances between them, althou h various types of grating may (5 By using parallel lines, a superior e ect is produced for this particular purpose, in contrast with gratings having lines crossing each other, because by using a single grating having parallel lines, the points of light in the picture to be transmitted are spread out only in the vertical direction instead of being spread out both'in the vertical and'in the horizontal direction. It is preferred to have the opaque lines of the grating held horizontally ratings having when the negative is taken. The negative thus produced is now used for making an enlarged positive by means of an ordinary a mate 'andwhite of eggs.

camera and it is preferred that this positive should be twice as large as the negative of the original picture. The enlarged positive thus produced is now printed upon a thin plate .made of copper or other. suitable bendable metal by 1 means of an ordinary printing frame.

his metal plate, which may be called the transmitting plate, has a sensitive coatto daylight but it is sufliciently sensitive to the powerful are light used for printing thereon from the enlarged positive so that a negative can be printed upon the transmitting plate.

It has een customary heretofore to expose the copper plate to the said are light for a period of about forty-five (45) seconds to produce the type of plate shown in Fig. 1.

According to this invention, the exposure is continued for about seventy-five (7 5) seconds so as to produce the type of plate found in Fig. 2, which corresponds exactly to the plate shown in Fig. 1, except for the difference in the time of exposure.

This printing is carried out for a sufficiently long period to enable the light gray background of the picture to appear as a solid black background in Fig. 2 and to also cause the light gray tones corresponding to the composition of the picture to appear as solid black or continuous areas in the improved negative found in Fig. '2.

After the copper plate-has been exposed, it is washed in cold water until the portions of the coating which have not been acted upon by the light are washed away and the plate is then dipped in aniline dye which is absorbed by the remaining glue or gelatine so as tofurnish a reproduction of the ima e,

in order to determine whether or not t e hotographic work has been properly done. he plate is then washed to remove any surplus dye and it isthen baked over suitable flame or the like until the adherent coating has been formed into a hard enamel-like insulating material. After the enamel has been formed, the plate is cleaned by rubbin it with a mixture of ordinary salt (NaGl and dilute acetic acid, as the action of the acid and of the salt (which is'an abrasive) removes any part of the gelatine which does not correspond to the image so as to produce clean" bri ht copper lines between parallel lines o' enamel of varying width transmission of the picture and illustrated in the previously mentioned Amstutz and 1 Baker patents, so that the lines of copper are arallel to the axis of the drum.

T 1e receiving mechanism may be of the electrolytic type shown in this Baker U. S. Patent No. 1,026,297 so that a negative of the picture to be transmitted is produced at the receiving station. The markings produced at the receiving station may be caused to spread out by making the point of the re-, producing stylus of suificient thickness so that a continuous tone reproduction is sccured at the receiving station, free from any of the line effects shown in Fig. 1 or in Fi 2.

Fractical experience has shown that in the s stem of transmission above mentioned that. t e reproduced picture does not show any sufiicient distinction between the various grayish tones found in the original picture so that a uniform flat efl'ect is produced which is undesirable because the outline of the picture is not distinct and cannot. be clearly distinguished from the background and because the body of the picture does not show any sufiicient' distinction or sharp gradation between the areas'or portionsofvarying grayish tone.

. Experience has shown, however, that by exposing the picture for a sufficiently long time so as to secure a late corresponding to a picture inwhich t e light gra tones 1 are replaced by solid white areas, t at the reproduced picture is clear in outline and in detail.

While the picture to be reproduced may be retouched in the ordinary manner now employed for making half tone reproductions, the over-exposure before mentioned obviates the necessity for retouching the background and in addition it automatically differentiates the light gray tones of the picture from the darker gray tones thereof, which could not be efi'ectively done by an artist.

The period of the additional or over-exposure may vary somewhat depending upon the character of the picture to be reproduced so that it is not intended to limit the invention to the specific example previously mentioned. 1

The over-exposure before mentioned is;

particularly important when the broken tone plate consists of a series of aralleland separated lines of varying wi th because a plate of this character omits so much of the detail in the ori inal picture that unless the lighter tones o the said picture are accentuated by over-exposure, the reproduced picture does not have a great deal of the detail found in the original. For this reason it has been proposed heretofore to use ordinary half tone transmitting plates in which the plate consisted of a series 0 separated dots of varying size, but the use of plates of this character for transmission purposes has been accompanied with such difiiculties that it has been proposed to use a transmitting plate composed of a series of separated and parallel lines of varying width.

According to this invention, it is possible to use a transmitting broken tone plate consisting of said parailel and separated lines of varying width and to produce a satisfactory reproduction of the original picture.

A preferred embodiment of this" invention has been disclosed, but it is clear that numer- Y ous chan es and omissions'could be made without eparting from its spirit.

We claim:

A method'of'transmitting a picture which consists in producing a series of electric ulses corresponding to the diiferences in ight value 0 the successive small areas of said picture, and producing electric pulses of the type which substantially correspond to a pure white tone in transmitting the small-areas which correspond to light grey tones In testimony whereof we hereunto afiixour signatures.

MARVIN FERREE. JOSEPH WISSMAR.

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