US2022014A - Method for making reflex copies - Google Patents

Description

N0 26, 1935 L. P. F. VAN DER GRINTEN 2,022,014

METHOD FOR MAKING REFLEX 4COPIES 4 Filed nec. 17, 1954 wfwrf/ azac/f y MW chemical power.

Patented Nov. 26, 1935 UNITED STATES 2,022,014 METHOD FOR MAKING REFLEX COPIES linamiikv Pieter Netherlands,

assignor to Frans van der Grinten, Venlo,

Naamlooze Vennootschap Chemische Fabriek L. van der Grinten,

Venlo, Netherlands, Aa pany of the Netherlands limited liability com- Application December 1'7, 1934, Serial No. 757,934

12 claims.

It is known tofmake reflex copies by a method comprising the steps of applying on an original a sheet containing a layer of sensitive material subjecting the original to a radiation through said sheet and subdividing said radiation before it has passed through the layer of sensitive material into small areas of lower and higher photo- Now it has been found that the strength of the picture can be increased by methods to be further described, whilst the type of the rays employed may be also of importance.

If one compares with the help of the microscope those parts of the reflexion copy that were during the vproduction of the latter over the dark regions of 'the original, with the employed subdivision into regions of greater and of smaller actinie intensity, consequently for example with the employed screening, there will be found in many cases that a considerable action on the sensitive layer in the portions of smaller photochemical action has occurred. The result of this action is hereinafter called the halo; it may for example be practically expressed by the reduction of the covering factor of the screening of the portions in question (the covering factor being the surface of the regions of smaller photochemical action, or the corresponding regions in the reflexion copy, per unit of surface). y

Now it has been found that the halo exerts an unexpectedly large injurious influence -on the strength of the picture. The objectl of the present invention is therefore to limit this halo. Wherever hereinafter reference is made to rays, or to transparency, or to capacity of reflexion therefore, this always means that reference is made to rays of such wave length as influence photochemically the sensitive layer or layers employed.

The requirements.necessary for the practical avoidance of a halo in the sensitive layer are dependent on many different factors, likewise the importance of the halo itself. They are determined inter alia by the kind and the coarseness of the subdivision into regions of greater and of smaller actinic intensity, which has been ern-'- ployed by the pictureimage distance is the distance in mm. between the layer in which the picture'is produced and the original) in relation thereto, by the nature of the applying between In the Netherlands December 19, 1933 original, and the like. The present invention, however, is not concerned with these factors but relates to methods of limiting the halo caused by an imperfect subdivision into regions of greater and smaller actinic intensit According to the invention this is effected by the screen, used for subdividing the radiation, and the sensitive layer in which the image has to be formed by the rays reected by the original, one or more auxiliary 10` layers of a sensitive material having a small transparency for the rays used, but becoming more transparent by radiation.

The invention is illustrated by the accompanying drawing, wherein Figure l shows a system embodying the original, sensitive sheet, auxiliary layer, and a double cylindrical lens screen.

Figure 2shows the system embodying the original, a double fold sheet having one side functioning as an auxiliary layer and the other a picture producing layer, and a single cylindrical lens screen.

In this drawing il is the original which is covered by a transparent carrier BL carrying the image forming layer b. HL is another transparent carrier carrying the auxiliary sensitive layer h. The carrier HL is covered by the cylindrical lens screen LRI, which may or may not be cover'ed with another lens screen LR2. The axes of the lenses should cross one another at Wide angles but this is not shown on the drawing for clearness sake. As shown the focal lines of both llens systems are located in one of the sensitive layers. A radiation impi'nging upon the lens screen LR2 or directly on LRI is condensed into small beams of rays, separated by areas in which only a diffused radiation takes place. The concentrated beams decompose the sensitive material first in the auxiliary layer h, then in the picture 40 producing layer b, strike the original and are reflected by the light parts of the original, the reflected rays forming the picture in the picture producing layer b. The diffused radiation between the concentrated beams strikes theauxiliary layer which is decomposed by it. As, howor image-distance (the lever, the intensity of this diffused radiation is much less than the intensity in the concentrated beams, it requires a considerable time before the auxiliary layer has been completely A' afforded by the auxiliary layer' should be sufficient to enablethe reexion copy to be formed without the possibility of any substantial action of the diffused rays on the picture producing layer in.

the portions of smaller photochemical activity.

In this manner it has been found possible to avoid a halo even in the case of a very imperfect subdivision of the radiation.

By the picture producing layer is meant one that is adapted to form the picture by means of any treatment whatever after the termination of the radiation.

By the auxiliary layer is meant one which does not take part in the picture production and which permits the rays that affect photochemically the picture producing layer` to pass through after suflicient radiation and less before such radiation.

During the production of the reflexion copy the picture producing layer must of course be located between the auxiliary layer and the original.. The greater the difference in transparency of the auxiliary layer before and after radiation, the more the halo is diminished. In the case of an auxiliary layer that contains a given sensitive material the halo diminishes with the quantity of radiation necessary to decompose the auxiliary layer. (Sensitivity of the layer.)` Toavoid an unduly long exposure and still obtain a reflex copy with a considerably reduced halo, it is desirable to use an auxiliary layer of a sensitivity such that after the production of the refiexion copy the auxiliary layer still exhibits a subdivision into regions of greater and ofsmaller transparency with a covering factorfthat corresponds to the subdivision employed and which appears after radiation. The aboveindicated limit of the sensitivity of the auxiliary layer is' lower as the sensitivity of the picture producing layer decreases,v

and/or as"the capacity for reflexion of the original decreases, and/or as the imperfections and/or the covering factor of the division increase.

Advantageously the distance or space between the auxiliary layer and the picture producing layer is made as small as possible.

In many cases the auxiliary layer and the `picture producing layer will be contained in separate sheets. They may also be present together in the same sheet, from which then the auxiliary layer may be removed as far as necessary for example by washing, exposure and so on. This, for example, a cyano-typeor blue-print layer naturally has an auxiliary layer, which circumstance renders the blue-print layer specially suitable in the sensev of the present invention for refiectography with subdivision into regions of greater and of smaller actinic intensity. The auxiliary layer and the picture producing layer may even form together one layer, in which case after a sufcient exposure to obtain a reexion copy the part of the layer acting as auxiliary layer is bleached away by a short exposurev to undivided radiation.

While lens screens have the advantage of subdividing a radiation, into regions of smaller and greater photochemical activity in an economical way they have, however, certain imperfections which may be counteracted by combining them -acetylcellulose sheet other is 0.12 mm. The

2,022,014 decomposed. As long as the auxiliary layer'isl with covering screens. But these combinations in practice are often times difficult to realize, especially when two crossed lens screens have to be'combined with a coveringl screen. When lens screens and especially crossed lens screens are used and an auxiliary layer is interposed vbetween them and the picture forming layer then these imperfections are counteracted effectively without the practical diiliculties of thelens screencovering screen combinations.

If it is desired to use in the picture producing layer a sensitive material the transparency of which is increased considerably by radiation, for example a diazotype-process layer, the same material may be used also for the auxiliary layer. A practical mode of carrying this out is the employment of a folded double sheet of this sensitive material. The sheet turned towards the screen then serves as the auxiliary layer and that turned towards the original serves as the pictureproducing layer.

'I'he use of the same sensitive material in the auxiliary layer as in the picture producing layer presents the advantage that the auxiliary layer will, as regards radiation, be less transparent exactly for those raysl which exert photochemical action cn the pictureproducing layer.

Example 1 On an original O (see Figure 1) there is placed a sensitive sheet (BL) with the side on which is the sensitive cyanotype-layer (b) turned away from. the original. Onthis-sensitive sheet there is placed a unilaterally saponified sensitive (HL) 0.1 mm. in thickness, which is coated on its saponii-led side with p-diazodiethylaniline and the coated side (h) is turned towards the original.l

The rst named sheet (BL) is intendedfor' the picture production, while the second (HL) serves as an auxiliary layer. This auxiliary layerhas before radiation a small transparency, which is increased by the radiation. y

On this system there is placed a cylindrical lens screen (LRI) in a celluloid foil of 0.4 mm., the

y lenses of which have a focal length of 0.5 mm.

whilst the distance ofthe focal lines between each lenses are turned away from the original. Another cylindrical lens screen (LR2) is placed thereon with its lenses turned towards the original so that the axes of the two screens cross one another.

In Figure 1 the lenses in (LR2) cannot be shown because their axes are parallel to the plane of the drawing; the dotted line c indicates the depth of the limit between two lenses. The lenses of (LRI) make the pencils of rays emerging from (LR2) to converge in a plane perpendicular to the plane of the drawing the focus of the lenses being in a plane within one of the sensitive layers. The rays arc thus focused in two directions crossing each other which makes them to converge into pointlike focuses located in a plane within one of the sensitive layers.

The entire system is well pressed together in a. pressing frame so that adequate contact is obtained between original sensitive sheets and screen. 'I'he radiation is effected by means of a punctiform arc lamp located at a distance of 40 cm. from the system. The radiation passes in sequence through the lens screens LR2 and LRI, the auxiliary layer h and the picture-producing layer b, and then impinges upon the original O. The sensitivity of the auxiliary layer is made such` that after exposure a. screen, structure appears thereon on iniscroscop'ic examination: For the purpose of making this screening more visible there is employedv a blue iilter or the auxiliary layer is developed.

The picture producing layer is fixed by immersion in a dilute potassium ferric cyanide solution and in water. There is obtained a negative reflexion copy which is stronger than would be obtained in a similar process but without an auxiliary layer. As a matter of fact the transparent portions show on microscopic observation a starshaped halo, located about the foci of the crossed cylindricalr lens system but to a smaller degree than would have been the case without the vernployment of the auxiliary layer.

As is known, blue-print layers lose their surface layer on fixing by washing with water. In this way a blue print layer so to speak always carriesl its auxiliary layer with it and it loses it on xing. This auxiliary layer, however, only has a relatively small effect. The action of the above described extra auxiliary layer is considerably greater. In general, the surroundings of the arc lamp will reilect a small quantity of light. This can be prevented by blacking these surroundings in which case a somewhat more sensitive auxiliary layer may be chosen.

Example 2 In the system described in Example l, for the auxiliary layer and the picture-producing'layer there ls substituted a double-fold sheet which is coated on one side with diazoethylbenzylaniline, in not too greatstrength, whilst the coated sides are in contact with each other. There is employed only a single cylindrical lens screen. (Compare Figure 2.) One side of the sheet functions as an auxiliary layer and the other as a picture producing la`yer. After exposure and development the latter shows actually a much smaller halo than would be the case if a clear photochemically inactive intermediate layer had been substituted for the auxiliary layer.

What I claim is:- y

Y 1. A method for making reflex copies comprising applying on an original a sheet containing afpicture producing layer of sensitive material, superimposing on said picture producing layer an auxiliary layer of sensitive material, which is initially substantially non-transparent to the rays subsequently used in making of the reilex copies but becomes transparent to such rays after having been acted upon by a suilicie'nt amount of radiation by such rays, subdividing a radiation into small regions of lower and higher photochemical activity, and causing said sub-divided radiation to pass through both of said layers on its way to the original.

l 2. Method according to claim 1 in which the auxiliary layer used is such that the difference in transparency before and after\radiation is great.

3. A method for making reflex copies comprising applying on an original a sheet containing a picture producing layer of sensitive material, superimposing on said picture producing layer an auxiliary layer of sensitive material, which is ,initially substantially non-transparent to the rays subsequently used in making of the reflex copies but becomes transparent to such rays after having been acted upon by a sulcient amount of ra.- diation by suchrays, causing a radiation to pass through a lens screen to subdivide said radiation into small regions of lower' andv higher photochemical activity, and causing said subdivided radiation to pass through both of said layers on its way to the original.

4. Method according to claim 1, in which the auxiliary layer is a part of 'the sheet containing the picture producing layer. 5

5. Method according to claim 1 in which the pictureproducing layer and the auxiliary layer are so arranged that there is practically no space between them.

6. Method.- according to claim l in which the 10 auxiliary layer used is one which has such sensitivity `to radiation that after the exposure required to make the reflex copy on the picture producing layer it is subdivided into regions of greater and smaller transparency. l5

'7. A method for making reflex copies comprising applying on an original a sheet containing a picture producing layer of sensitive material, superimposing on said picture producing layeran auxiliary layer containing the same sensitive ma- 20 terial as that of said picture producing layer, said auxiliary layer being initially substantially nontransparent tothe rays subsequently used in making of the reflex copies but becoming transparent to such rays after having been acted upon by a suilicient amount of radiation by such rays, subdividing a radiation into small regions of lower and higher photochemical activity, and causing said subdivided radiation to pass through both of said layers on its way to the original.

8. A method for making reex copies comprising selecting a sheet containing a picture producing layer of sensitive material which material is initially substantially non-transparent to the rays subsequently used in making the reflex copies but tion by such rays, folding said sheet in such manner as to form two layers in contact with each other, applying said folded sheet on an original, subdivlding a radiationinto small regions of lower and higher photochemical activity and causing said subdived radiation to pass through both of said layers on -its way to the original. y

9. The method according to claim 1 in which 45 the auxiliary layer and the picture producing layer are combined in one layer. f

l0. A method for making reflex copies comprising applying on 'an original a sheet containing a picture producing layer of sensitive material, superimposing on said picture producing layer an auxiliary layer of a sensitive diazo compound, said auxiliary layer beinginitially substantially non-transparent to the rays subsequently used in making of therefiex copies lbut becoming transparent to such rays after having been acted upon by a sumcient amount of radiation by such rays, subdivlding a radiation into small regions of lower and higher photochemical activity, and causing said subdivided radiation to pass through both of said layers on its way to the original.

11. A method for making reflexvcopies comprising applying on an original a sheet containing a picture producing layer of sensitive material, superimposing on said picture producing layer an 05 auxiliary layer of a sensitive cyanotype composition, said auxiliary layer being initially substantially non-transparent to the rays subsequently used in making of the reflex copies but becoming transparent to such rays after having been acted upon by a sulilcient amount of radiation by such rays, subdividing a' radiation into small regions of lower and higher photochemical activity, and

12. A niethod for making reflex copies comprising applying on an original a sheet containing a pictureproducing layer of Vsensitive material, su-

perimposing on said picture producing layer an butbecoming transparent to such rays aftex` having been acted upon by a sumcient amount otra.'- diation by such rays, subdlvidinga radiation into small regions of lower and higher photochemical activity, and causing said subdivided radiation to.'

pass through both of said layers on its way to the 5 original.

LODEWIJK PIETER FRANS l vm mm GRINTEN.

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