US1157197A

US1157197A - Printing-plate for colored photo-engraving and the process for producing the same.

Info

Publication number: US1157197A
Application number: US86011214A
Authority: US
Inventors: Fletcher V Walsh; Colvin M Reed
Original assignee: Individual
Current assignee: Individual
Priority date: 1914-09-01
Filing date: 1914-09-01
Publication date: 1915-10-19
Anticipated expiration: 1932-10-19

Description

F. V. WALSH & C. M. REED.

PRINTING PLATE FOR COLORED PHOTO ENGRAVING AND THE PROCESS FOR PRODUCING THE SAME.

APPLICATION r1150 SEPT. l. 1914.

1,157,197. Patented 001. 19,1915.

4 SHEETSSHEET I.

F. V. WALSH & C. M. REED.

APPLICATION FILED SEPT. I. 1914.

Patented Oct. 19, 1915.

4 SHEETSSHEET 2.

J 9 10 T a" 7%? 4 HUN 1 7 H I I i V l'li'm m- I i k I! II II T 1 Mfimsies K7? 14. 11751? F. V. WALSH & C. M. REED.

APPLICATION FILED SEPT. I. I914.

1,157,197. Patented 001. 19, 1915.

4 SHEETSSHEET 3.

[ti/I7 E5585 7 fiII BIJDFS W I 2% 1 W. 21 1641,.

The/h AF.

F. V. WALSH & C. M. REED.

APPLICATION FILED SEPT. I. 1914.

Patented Oct. 19, 1915.

4 SHEETSSHEET 4 Fyfil i ly M 71185585 f/V J rrE 2| STA FLETCHER WALSH AND COLVIN REED, OF SAN FRANCISCO, CALIFORNIA.

i PRTNTING-PLATE FOR COLORED PHQTO-ENGRAVING AND THE PROCESS FOR PRODUCING THE SAME.

. To all whom it may concern.

- States, residing second or third plate in Be it known that we, FLETCHER V. WALSH and CoLvIN M. REED, citizens of the United in the city and county of San Francisco and State ofCalifornia, have invented new and useful Printing Plates for Colored Photo-Engraving and the Process for Producing the Same, of which the following is a specification.

The invention relates to printing plates for colored photo-engraving and the process of producing the same and has especial reference to the shifting of the screen through which the subject is projected onto the exposed negative, and it consists of the printing plates and the improved method of shifting the screen so that the resulting dots on one plate or color record will always bear the same relative position to the dots on all of the other plates.

One of the most lmportant characteristics of the process for producing colored photoengraved printing plates is that the dots on the said plates shall bear the same relative position to each other on the finished printed picture in order to reproduce a uniform graduation of shades and tints without producing what is known as a moir antique result, or pattern. 4

Printing plates constructed in accordance with our present invention comprise a series of plates wherein the dots printed from one plate will overlap the dots printed from a a uniform degree throughout the printing surface.

. The features of the invention are first, to

. produce a series of different screen negatives from one screen that will print'a rec- 0rd of each color in dots that uniformlyoverlap the dots of the other plates; second, to provide means whereby the pattern or moire antique result of the present process will be eliminated; third to provide means whereby va greater number of plates or color records may beused to the end that a greater number of colors may be printed and uniformly blended together, thereby re sulting in a finer and more artistic reproduction.

The accompanying drawings, which form a part hereof, represent the invention in its preferred form.

Figure l is a vertical longitudinal sec- Specification of Letters Patent.

' of an ordinary screen,

Patented Oct. 19, 1915.

Application filed September 1, 1914. Serial No. 860,112.

tional view of a photo-engraving camera disclosing the screen in position, the negative behind the screen, and the movable lens slidably mounted upon the front of the camera the dotted, and the dot and dash lines indicating the first and second positions of the projected subject. Fig. 2 is a front elevation of the front end of the camera disclosing the lens slidably mounted therein and the means whereby the said lens is shifted. Fig. 3 is a sectional viewtaken on line XX of Fig. 2 of the drawings. Fig. 4 is a front elevation of a screen, the upper half of which discloses the result when the screen has been ance with the present invention disclosing the absolute lack-of the moir antique result or pattern. Fig.. 5 is a greatly enlarged diagrammatic view of the dots resulting from the present invention wherein is shown the manner in which the dots of one plate, shown in full lines, are uniformly overlapped by the dots, indicated in dotted lihes, of a second plate. Fig. 6 is a front elevation wherein for purposes of better illustration, the lines are disclosed as running in one direction only instead of crossing each other at right angles. Fig. 7 is a view of two screens wherein the lines run at angles to each other as in the present state of the art thereby producing the pattern or moir antique result.

In order that a clear understanding of'the present invention may be had it is necessary to describe the process used in the present state of the art, which is as follows: In the present state of the art printing plates are produced by photographing the subject onto a negative. It is only possible to approximate to the printing of a flat or graduated such as appears in photography, by

tone, producing a broken or granulated surface which shall present a series of lines or dots. that, when inked and impressed upon paper,

shifted in accord ing each other at right angles, the result be-- It is a photograph of so much of the sub ject as could effect the negative'through the little clear squares of the screen, and represent the tones of it by innumerable little dots, the size and proximity of which are regulated by the fineness or coarseness of the screen used.

In reproducing a colored picture a negative or record of each separate color is obtained by photographing the subject through a separate filter. Each filter will absorb and refuse passage to certain colored rays, while permitting the passage ofothers. For instance, a filter of a certain color will absorb and stop the passage of red and green rays, while permitting the passage through it of a violet or blue. When a colored subject is placed before the camera, with one of these filters between it and the exposed negative, the rays of light of the color which can pass through the filter to the negative will be the only ones. which can affect it. In. this manner it is possible to obtain, on separate negatives and by meansof separate filters, one for each negative, a record of each primary color of the subject. These records are not colored photographs but negatives which may be translated into color by the use of colored inks. The principle governing the process is analysi'sor separation followed by recombination. Whenprinting plates made from these separate negatives are inked and printed one over the other they combine again the colors which were separated by the filtering process and give approximately 'a reproduction of the original subject in its true colors. In printing with these separate plates, it is evident that were the same screen used in their production the lines or dots would print on top of one another; but a great deal of the color results depends upon a considerable portion of each color being on the white paper. Consequently it is necessary to turn the screen at a different color 'lie at an angle to all of the other screens used for all of the other colors, v he crossing. of the screen lines will produce the finished product whatis known of the knob 14 present invention entirely eliminates the moir antique result, thereby allowing a greater number of color records, and conse quently, a more artistic and faithful reproduction of the original subject. The present invention also provides a means whereby a number of color records or plates may be produced through the same screen without tulrfning the lines thereon, or the screen it se Instead of using different screens having the lines thereon at difierent angles for each separate plate, if the same screen is used but shifted on a line parallel with one set of lines on the said screen each time aseparate negative is exposed, it is evident that when the negatives are developed and the printing plates made therefrom inked and impressed upon a sheet of paper that the dots printed from one plate will overlap the dots printed from the other plates in proportion to the amount that the screen was shifted. In other words, instead of changing the relative positions of the dots for each plate by turning the screen a more uniform relation of the dots is obtained by shifting the screen on 'a' line parallel with the lines thereon, which will give the eflect disclosed in the upper half of Fig. 4- and in Fig. 5 of the drawings, said upper half of Fig. 4 having been shifted in the direction indicated by the inclined arrow.

As it is not deemed practical to shift the screen we have provided means for producing the same result which consists in shifting the lens on the camera which is accomplished in the following manner.

Referring to the drawings the numeral 1- is used to designate a photo-engraving cam-,

era of the usual type and 2 is a plate holder mounted within the back thereof. The negative 3 to be exposed is placed within the plate holder 2 and back of the screen 4. The subject 5 is projected through the lens 6, in the front end of the camera 1, and the screen 4 onto the negative 3. a

The lens6 is mounted upon a plate 7 which is slidably mounted within the guides -8 secured to the front 12 of the camera 1.

The plate 7 is provided with .a lug 9 ar-' ranged to engage the threaded portion 10 of a stem 11 rotatably mounted within astandard 15 secured to the front 12 of the camera 1. The stem 11 isprovided with a suitable knob 14 having suitable graduations thereon by means of which the amount of rotation and stem 11 may be indicated.

The. central or normal position of the lens 6 is indicated by means of a mark 17 on one edge of .the plate 7 which registers with a similar mark 18 on .the adjacent edge of the guide 8 on that side of the said plate 7. The registration of the mark 17 with the mark 18 is facilitated by means of a small magnifying glass 19 mounted upon the guide 8 and directly over the said mark 18.

In producing the successive negatives, one for each color, the first negative is placed in the camera 1 and exposed in the usual manner, through the proper filter, not shown, for the color to be registered. The first negative is then removed and a second negative, and appropriate filter, is placed in position. Instead of moving the screen 4 in a line parallel with one set of lines on the said screen, the image is slightly shifted by,

turning the knob 14 the desired amount which will shift the plate 7 and the lens 6 therein. The second negative is then exposed, through an appropriate filter. Each time a successive negative is exposed the lens 6 is shifted so that the resulting dots will each lie in a different position on each different negative.

While the lens 6 is shifted before each successive negative is exposed so that the dots on any two plates will not register, it must be understood that the said dots on one plate will always bear the same relative position to the dots on every other plate in the series.

In Fig. 5 of the drawings we have illustrated the relative positions of the dots resulting from one plate or negative to the dots resulting from another plate or negat1ve.

It is obvious from the foregoingthat we have provided an improved series of plates for color printing and an improved process for producing the same wherein more artistic results may be obtained, a greater number of colors and color plates may be used, and where only one screen is necessary for the production of the said plates. It is also ob.- vious that the direction of inclination, or the angle at which the projection or lens is shifted is immaterial if the lens or projection is shifted in a line parallel with one set of lines on the screen. It is also evident that the lens may be stationary and the screen shifted. on a line parallel with one set of lines on the Said screen with the same results.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is 1. Printing plates for a colored photoengraving process comprising a series of half-tone plates Whereon the lines running in one direction and formed of dots or lines on one plate will register-with similar lines on the other plates, and the lines running at right angles to the first mentioned lines and likewise formed of dots or lines will a screen andof shifting the projection on each successive negative exposed an equal amount so that the resulting dots or lines on one plate will'uniformly overlap the dots or lines on every other plate.

4. The process of producing color printing plates which consists of projecting the subject onto the exposed negatives through a screen and of shifting the projection on each successive negative exposed an equal amount on a line parallel with oneset of lines on the screen so that the resulting dots or lines on one plate will uniformly o erlap the dots and lines on every other plate.

In witness whereof We hereunto set our signatures in the presence of two subscribing witnesses.

FLETCHER V. WALSH. COLVIN M. REED.

Witnesses:

IRENE DowNEY, D. B. RICHARDS.