US1945569A - Printing process and apparatus - Google Patents

Description

Feb. 6, 1934. G. s. RowELL. 1,945,569

PRINTING PROCESS AND APPARATUS Filed Nov. 2a, 1930 attnue W4 Patented F eli. 6, 1934 1,945,569 PRINTING rnocnss AND APPARATUS George S. Rowell, Cleveland, Ohio, assignor, by mesne assignments, to Multigraph Company, Wilmington, Del., a corporation of Delaware Application November 28, 193i Serial No. 498,616

1l Claims.

An object of this invention is to provide a printing process by which typewritten copy, for example, may be more easily reproduced, in cooperation with suitable planographic or like printing l apparatus, than by the previously known methods.

A specic object is to provide an improved, simple and effective design or image carrying negative (or positive) as one of the steps in preparing a printing plate or roll to place a printing image l thereon. Other objects include the provision of an improved printing medium which may be used in obtaining a screened image, or background, without requiring the usual photographic screen ina camera, thus reducing the number of steps 16 and materials, as well as minimizing equipment for this class of work. Other objects and features of the invention will become apparent from the following description relating to the accompanying drawing which illustrates, diagrammatically, the preferred instrumentalities used. The essential characteristics of the invention are summarized in the claims.

In the drawing, Fig. 1 is an enlarged plan view of asection of suitable material carrying one form of screen design; Fig. 2 is a view similar to Fig. 1 showing another exemplary screen design; Fig. 3 is a greatly enlarged sectional view of a prepared sheet before the image is placed thereon; Fig. 4 is a view similar to Fig. 3 showing one manner of mechanically forming the image, and Fig. 5 is an enlarged plan view of a portion of the sheet shown in Fig. 4 bearing an exemplary image.

Figs. 6, 'l and 8 are enlarged fragmentary sec.-

tional views of the mechanical negative, such as shown in Fig. 4, but showing the manner' of use thereof for producing so-called intaglio printing effects, white on black for example. Fig. 9 is a fragmentary enlarged plan view of a portion of a sheet prepared in accordance with Figs. 6 40. to 8 to produce the intaglio effects. Fig. 10 shows a fragmentary enlarged sectional view of a portion of a printing platebearing the resulting imagev transferred from a negative similar to Fig.

5; Fig. 11 is an enlarged plan view showing more fully the character of an image produced on the plate in accordance with Fig. 10; Fig. 12 is an enlarged sectional view illustrating another manner in which the screen eil'ect may be applied with reference to the coating; Fig. 13 is a view similar to Fig. 12 showing a double screen effect,

and Fig. 14 is a plan view oi' a small section of the elements shown in Fig. 13, which has been suitably treated to form an image.

Referring in detail to the drawing, and rst to the group of figures, 1 to 5, one manner of carrying out the invention is to first provide a suitable base, such as translucent paper. celluloid, celophane or the like, indicated at 1 with a screen effect 2. Two different examples of screen design are shown (Figs. 1 and 2) but as a matter of fact, 60 any screen configuration may be employed.

The screen effect may be formed as permanent or removable images. In case permanent images are desired, these may be printed in suitable ink or dye, or may be embossed onto or sunk into the base material, or may be aflxed by the action of light. In case removable screen images are desired, these may be formed as above noted, but in sensitive material (sensitive to mechanical treatment, by abrasion, by fracture, or by solvent, or sensitive to known or suitable photo-mechanical treatment).

The preferred manner of printing the screen effect is by means of a printing press of any convenient type. The screen image 2 may be print- 75 ed on the base 1 in ink which will effectively resist the passage of photographic rays. For example, the ink may be black, red or yellow. Preferably it is black. In the case of reproducing typewriting with the final plate, almost any screen design will breakup the image to closely simulate typewriting by means of an ink ribbon. On top of the printed screen design, I now place a coating 3 of suitable thickness', which coating is sensitive to mechanical action so that portions of the same may be removedor treated `to form the desired image. In this particular group of figures, it is assumed that the coating is sensitive to impact or other purely mechanical treatment.

The coating 3 in Figs. 41 to 5 preferably comprises material which is frangible or friable. A suitable substance is shellac, dissolved in borax and water. This coating is provided with suitable pigment, -so that it is generally opaque to -the passage of actinic rays. The'coating solution may contain a suitable dye for example, or pigment material, such as carbon black, mechanically mixed with shellac or applied, say on top, as a separate layer. Fig. 4 illustrates the manner in which an image may be formed by ymeans of a die, such as the character die of altypewriter, it being understood that the whole sheet prepared in accordance with Fig. 3 may be of such dimensions as to be readily insertable into a typewriter for forming a page of matter to be reproduced by printing. The type T (Fig. 4) of the typewriter simply fractures the coating 3 and reduces it to a powder wherever the type strikes the coating.y The ridue of powder left on` the der in a known or convenient manner.

base 1 may afterward be easily blown of! or brushed off, whereupon the negative is complete and ready for the transference of the image or images 6 onto a suitable printing plate or cylin- It will be seen from Fig. 5 that the background areas on the resulting sheet are substantially entirely opaque to actinic rays; likewise, the screen effect at 2a on the image is substantially opaque. Except for this screen effect, however, the image shown as a capital letter Ain Fig. 5, is entirely translucent and this image may, therefore, be light printed onto the printing plate carrying a suitable light sensitive film, such as a colloid of albumin and suitable light sensitive salt. The process just outlined is exceedingly simple as compared to previous practice known to me, and the image portions of the plate will be broken up by the screen effect with the usual advantageous results. The process requires no screen in the usual sense, this being supplied on the negative base 1, wherefore the user has only to form the desired images, as with a typewriter, and prepare the printing plate therefrom in the desired manner,.i. e. in accordance with his printing equipment.

The medium above described lends itself to obtaining so-called intaglio printing effects in a very simple way, as illustrated in Figs. 6 to 9. Here the base 1 and coating 3, overlying the screen effect 2, has an image transmitted thereto as before. After this mechanical negative of Fig. 6 has been dusted or suitably cleaned to remove the fractured material from the image portions, the sheet is coated with a suitable ink, such as the ordinary developer ink. This is of greasy character and adheres to the base material 1, whether thisis paper or a transparent substance like cellophane, but on the high surface portions of the coating 3 the developer ink spreads out into a very thin porous layer in the process of being rolled up as with an ink roller. The developer ink allows a solvent, such as water, to go through the film of ink at 'I while the heavy layer of this ink at 8 remains undisturbed on the base 1, overlying the screen effect 2. The result of washing the negative is illustrated in Fig. 8. and herein it will be seen that the screen effect 2 is entirely exposed by the removal of the light coating of developer ink and the coating 3, leaving a greasy image at 8 of sufficient thickness to obstruct light rays in the subsequent procedure. Instead of washing off the film 7 of the developer ink and the coating 3, the base 1 may instead be drawn over a comparatively sharp edge (coating side opposite the edge), fracturing all of the coating 3 and allowing it to be readily brushed off but leaving the image portion or portions 8 intact.

It may be mentioned, at this point, that where the use of the medium (1-2-3) is such as to require removing the coating 3 with a solvent, materials such as dextrine, various sugars, or albumin are more readily adapted than the shellac-borax combination.

'I'he negative, a small section of which is. shown in Fig. 9, may now be transferred by the action of light to a printing plate carrying the light sensitive colloid film, and it will be seen that the major portions of this plate will be light treated so that in case this is a planographic plate, ink will not take on these major or non-image portions, whereas it will take on the image portion corresponding to 8, and on the screen effect 2 corresponding in position to the lines 2. The screen effect breaks up the solid blacks on the plate as in ordinary tone-printing processes, insuring a higher quality of printing, whenever this is desired.`

In lieu of the above procedure, with reference to Figs. 6 to 9, I may instead type directly onto a sheet of suitable thin or translucent paper orv cellophane or like substance, having the screen design 2 previously printed or embossed thereon, using, for example, a strip of carbon paper adjacent the screen side of the sheet, thus getting substantially the effect of Fig. 9 without the intermediate steps of rolling up with ink and dissolving or fracturing off a coating, such as 3. It will be understood, however, that the real advantage of obtaining an intaglio printing effect in accordance with the above specific description of Figs. 6 to 9, is that at any time the medium according to Figs. 1 to 5 may be converted into a negative for producing White on black (herein called by its trade name intaglio printing) thus making a. single medium suffice for producing both kinds of printing plates, whenever both kinds, for a single set-up of copy, may be desired.

The manner of using mediums on the order of those shown in Figs. 5, and 9 to produce an image on a printing plate bearing a light sensitive lm is well known, but to complete the process the medium may be placed with the treated surface face down, on the plate and a suitable source of light applied to effect corresponding image and non-image areas on a sensitized colloid i'llm on a plate such as shown at 22, Figs. 10 and 1l. After the image has been transferred to the plate, as' above outlined, and the untreated portions of the colloid film on the plate washed off, the screened image portions will remain on the plate as at 21, whereas the nonimage portions of the lrn will readily wash off, leaving the plate bare in the non-image areas. Afterward, the plate may be treated to render the non-image lportions repulsive to printing ink, and the image portions receptive to such ink, in known or suitable ways. The above method of using the screened medium is as used to produce planographic plates or rolls but it is to be understood that the invention is not confined to this particular class of printing, since it is, for further example, just as applicable to the production of true intaglio printing members.

Referring now to Fig. 12, this illustrates anothermanner in which the screen effect may be obtained on a suitable base, thus producing either a permanent or removable screen effect with materials such as heretofore described. Here the screen image is shown at 2a on the reverse side of the sheet 1, that is to say, the screen image is on the opposite side from the sensitive coating 3. This device, particularly where the screen formation is frangible, soluble, etc. makes it easier to remove portions of the screen effect, as for special shading of certain zones of the image, or background, as the case may be.

. If the screen effect is .to be frangible, I may the two screen effects being on opposite sides of the base material 1. These two screen images may be exactly alike and out of registration with each other, or the screen design on one side may be of a different design from that on the other.

For example, let us suppose that the screen effect at 2a comprises lines and the screen eect at 2b' suitable dots. Thus, irrespective of whether one or both of the screen effects is permanent or removable, a double screen pattern results, comparable to the so-called duatone effects, now 4produced by photoengravers and lithographers, by exposing. a plate or film twice, each time with a different screen.

Fig. 14 shows an image at 40 formed as by fracturing the sensitive coating 3, for example, the dot screen design at 2b on the coating side of the base being shown in full lines, and the line screen design on the opposite side being shown in broken lines.

It is desired to be understood that all the above described treatments, as elements in the present printing process may be used separately or in various combinations. For example, I contemplate, particularly, forming a permanent (insensitive) screen on one side of the sheet and a removable (sensitive) screen on the opposite side, and these screens may be similar or dissimilar, and the sensitivity may be obtained in various manners. v

I claim:

1. In a printing process, the steps of preparing a negative medium for transmission of light toa suitably treated printing plate, consisting in forming a screen effect on a translucent base, covering the screen effect with an opaque frangible substance and then mechanically fracturing certain portions of such substance to define the images to be printed and in such manner that the image portions will transmit light through the screen effect while the remaining portions will obstruct light. y

2. A'printing process, comprising preparing a translucent base to form anegative medium by applying screens to opposite sides thereof, applying a uniform opaque coating over one of said screens, and treating the coating thus formed to define contrasting opaque and translucent image and background portions.

3. A printing process, comprising preparing a base of translucent material with a partially opaque screen effect, applying a uniform coating over'said screen eect, mechanically treating the coating to remove portions thereof to define an image, applying light obstructing material to said image portions of the negative, and then removing portions of the coating surrounding the image lthus formed, whereby the said medium becomes a negative for producing a printing plate in a known manner which will print with whiteon-black effect.

4. A mechanical negative, comprising a suitable translucent base with a screen, and a coating thereon of frangible material, said frangible material being removable by impact'to define an image.

5. A mechanical negative, comprising a thin pliable translucent base, a screen effect carried on said base and forming a permanent part thereof, and a substantially opaque coating covering said base, the coating being of such nature that it may be ruptured by the action of a typewriter die or other suitable tool thereon, whereby light may be transmitted through the ruptured regions.

6. In a printing process, preparing a negative base by forming thereon a suitable screen design, coating the base with a frangible substance and mechanically treating the frangible substance to remove portions thereof without disturbing the screen design.

7. As a new article of manufacture, a sheet for the production of a negative for photo-mechanical printing comprising a translucent base,

screens on opposite sides thereof, one of said screens being readily removable, and an opaque coating of material adapted to be ruptured to allow the passage of light.

8. A mechanical negative, comprising a suitable translucent base with a screen on one side thereof, and a uniform coating on the base adapted to have itsy continuity interrupted..

9. A process of making a mechanical negative comprising preparing a translucent base to form a negative medium. by applying thereto a uniform coating and a screen effect, and thereafter forming the image to be printed by removing portions of the coating. Y

10. A process of making a mechanical negative,

comprising preparing a negative base by mechan- Y lically forming thereon a suitable screen design,

base and adaptedto have portions thereof removed to render the negative -light-transmissive and lightobstructive in respective definite areas.

GEORGE s. RowELL.

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