US1575408A

US1575408A - Method of and apparatus for making negatives from which printing plates may be produced

Info

Publication number: US1575408A
Application number: US740967A
Authority: US
Inventors: Bassani Laurent
Original assignee: BASSANI PROCESSES Inc
Current assignee: BASSANI PROCESSES Inc
Priority date: 1923-10-04
Filing date: 1924-10-01
Publication date: 1926-03-02
Anticipated expiration: 1943-03-02

Description

March. .2 1926. 1,575,408 W TUS FOR MAKING NEGATIVES FROM WHICH PRINTING L. BASSANI METHOD OF AND APPARA PLATES MAY BE PRODUCED Filed 001;. 1. 1924 2 Sheets-Sheet 1 a G. 0 0 Q avwentoz Lauren? 5055a" March 2 1926. 1,575,408

BASSANI METHOD OF AND APPARATUS FOR MAKING NEGATIVES FROM WHICH PRINTING D PLATES MAY BE PRODUCED Filed 001;. 1, 1924 2 Sheets-Sheet 2 Gum/nea i so Patented Mar. 2 1926.

UNITED STATES PATENT OFFICE.

LAURENT BASSANI, OF NEUlLLY-sUR sElNE, FRANCE, ASSIGNOR, BY MESNE AS- SIGNMENTS, '10 BASSANI PROCESSES, INC., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

METHOD OF AND APPARATUS FOR MAKQQ'G NEGATIVES FROM WHICH PRINTING i PLATES MAY BE PRODUCED.

Application filed October 1, 1924. Serial No. 740,967.

To alll whom it may concern:

Be it known that I, LAURENT BAssANI, subject of the King of Italy, residing at 4 Rue dArmenonville, Neuilly-sur-Seine, Seine, in the Republic of France, have invented new and useful Improvements in Methods of and Apparatus for Making Negatives from Which Printing Plates May be. Produced, of which the following is a'specification.

My invention relates to improvements in process photography and has reference more particularly to a processof and apparatus for obtaining photographic images juxtaposed and superposed on one vand the same sensitive surface during the exposure. Transverse displacement of the crossruled screens used in process photography has already been applied for the purpose of shifting the pencils of light passing through the transparent spaces of the grating, so asto obtain the spreading or enlargement of the portions of the surface of the sensitive plate which are affected by the action of the pencils of light and which constitute the opaque elements of said sensitive plate, this enlargement necessarily being effected to the detriment of the transparent points of the y negative, which become smaller, resulting in upon the metal a reduction of the points appearing in the 'white spaces of the subject in the transfer or upon a lithographic surface. s

It has already been discovered that the transverse displacement of the cross-ruled screens maybe successfully effected in different orientations, according to the geometric constitution of the said cross-ruled screens.

Various known devices admit of the production. of the dlsplacement under the conditions indicated. These devices in fact, permit modification of the rectilinear dis; placement of the screen and -regulation of the amplitude of this displacement. Nevertheless; the modifications in orlentation of the displacement of the cross-ruled screens have been obtained only by the operation of mechanical devices arranged in the'interior of the camera. Successful operation of such 1 devices necessitates the removal of the plateholder, in consequence of which it is not possible during the course of the exposure, to modify the orientation of the rectilinear displacement of the screen, since the 'removal of the plate-holder and locating it again would involve the risk of disturbing the precise position of the sensitive plate arranged. in the holder.

The present invention "has for its object to provide a process for obtaining photographic images which may be utilized in process work enerally. I accomplish this object by afi ing the same sensitive surface successively and partially to the action of light so as to constitute underexposed or overexposed elements. which by their combination will constitute a single image obtained with difierent lengths of exposure,

this effect being made possible by means of the suitable displacement of the screen in its own plane, a displacement which may be of subjects in colors by using, at each of the displacements of the cross-ruled screen,

color selection screens for the different colorings of the subject, so as to produce on the same sensitive surface, tone values proportional to these different colorings.

' A further provide suita le apparatus to carry out the above process, and the purpose is accomplished by means of certain arrangements and combinations of parts hereinafter more fully. described.

Briefly stated the present apparatus com prises a device by means of which it is pos-. sible to obtain, simultaneously withthe rectilinear displacement ofthe cross-ruled screen in all orientation, the circular displacement of said screen about the geometriccenters of the transparent elements of the grating, the'modifications of amplitude and of rectilinear orientation, as well as the transformation of the rectilinear displacement *intocircular displacement andvice versa, 'all such movement being obtained instantaneously by operation of parts .disposed on the outside of the camera. This urpose of my invention is tocamera likewise makes it possible to control, from the outside and on an enlarged scale, the amplitude of the displacement, the camera having for this purpose a diaphragm which .has the shape of the elements of the screen and which is displaced over a sight of the same shape. The dimensions of the sight and of the diaphragm, aswell as the amplitude of the displacement are proportional to the dimensions of the transparent elements of the grating and to the amplitude of the displacement of the screen.

The invention is illustratively exemplified in the accompanying drawing, in which Figs. 1, 2, 3, 5, and 6 are diagrams on a large scale showing the luminous locations left by the cross-ruled screen on the sensitive surface, and the effect of the displacements of said screen in certain directions.

Fig. 4: is a diagram of the reproduction camera.

Fig. 7 is the front view of the device that serves to displace the cross-ruled screen in any orientation and any amplitude.

' Fig. 8 is-the profile View thereof.

Fig. 9 is a transverse section made along a b of Fig. 7 and broken away at the left.

My im roved process consists in afl'ecting one and tie same sensitive surface by means of several successive exposures: A first-exposure will make it possible to obtain a late in which the elements constituting the lacks of the subject will be formed in the usual manner, a second exposure will make it possible to eliminate completely the points in the pure whites of the subject after having suitably displaced the cross-ruled screen. This second exposure will be relatively short, so as to make sure that the pencils of weak light reflected by the dark tints of the original have not had time to affect the sensitive surface; it must nevertheless be sufficient to allow the pencils of bright light reflected by the whites ofthe subject to have time themselves to affect the said sensitive surface. This action of the pencils of light will not be limited absolutely to the full whites of the subject; it will manifest itself to an extent decreasing from the full whites to the light half tints,

andit willhave the effect of reducing the transparent points of the plate by changing" their form, in the; direction of the displacement of the cross-ruled screen, so that the points which will express the bright tints of the subject will, be deformed and will present the appearance of Fig. 1.

' The constitution of points formed as in Fig. 1 will tend to give the combination of the elements corresponding to the bright tints a hatched appearance, which will be the more apparent the greater a displacement of the cross-ruled screen was required by the or1ginal.

It maybe desirable to obviate this hatched appearance, preserving for the points their original form, and to obtain their reduction over the entire circumference of the points formed by the original exposure. In order to obtain this result, the cross-ruled screen will have to be displaced,'not in a rectilinear direction as before, but circularly about goemetric centers of the transparent elements of the screen, so as to obtain an action of the pencils of light over the entire circumference of the points originally established by the principal exposure. In that case the displacement of the screen will be very slight. It is necessary to observe, in fact, that the displacement of the screen will have, for the elements constituting the half tints, a different action according as it is oriented in one direction or in another.

If the original exposure has established on the sensitive surface points of the form shown in Fig. 2, and if the cross-ruled screen is displaced in the direction of the' same length, the action of the pencil of Li ht will manifest itself along two'bands of surface 6 and a; calculation will show that the surface of the bands of additional influence b and 0 (Fig. 3) is greater than.

the surface of the band a (Fig. 2).

The surface of additional influence obtained by. the circular displacement of the screen about geometric centers of the transparent elements of the cross-ruled screen will be greater still than in the case of the preceding rectilinear displacements; but the time of exposure necessary to obtain a sufficient impression of the sensitive surface will go on increasing. At any rate, it is desirable to make it possible for the operator easily to alter, in the course of the exposure, either the orientation of the rectilinear displacement of the screen or the amplitude of the circular displacement about geometric centers of the transparent elements of the cross-ruled screen.

On'the other'hand, the displacement of the cross-ruled screen may be applied to obtaining photographic images from subjects in half tint by juxtaposition or superposition of the elements of two or more images produced on one and the same sensitive surface, after successive and partial shuttingsoff of this surface, according to one method of procedure, making it possible to obtain a combined image which will be the resultant of the juxtaposed or superposed elements obtained on one and the same sensitive surface with different times of exposure.

the usual means,

In Fig. 4 there is seen at s the source of light of an elementary photographic reproduction unit, including a frame arranged to receive a negative plate 1, a board 2 supporting the objective 3, an adjustable grat- 'mg-carrymg frame 4 arranged to receive a cross-ruled screen 5, a frame with a curtain 6in which there-is arranged a sensitive surface 7. r

If it is proposed to produce on the sensitive surface 7 a positive image of the negative 1, the cross-ruled screen 5-be1ng removed, i. e., the process being carried on. by it will be observed that the time of exposure necessary to obtain a positive image that is complete and satisfactory in values will have to be determined with precision, and it will be observed that an underexposed plate will give more vigorous blacks, whereas an overexposed plate will give, in general, more details and less effect; the operation will thus be rendered easier and the result will be given all the desirable qualities by producing on the sensitive surface one or more images'or exposures graduated within certain limits, in such manner that the elements constituting these images produce the effect of a single image uniting the qualities of the multiple images which produce it.

It would have been possible to operate differently, by producing 'the displacement of the cross-ruled screen in different directions and by proceeding with the use of several insolat ions, and to expose, for example, for'2 minutes in .the original position of the screen and by causing the screen to be displaced in the direction of the arrow 7,

Fig. 6, to a distance equal to the semidiagonal of one element of the screen and by exposing the uncovered portion of the sensitive surface for 2 further minutes, the displacement of the cross-ruled screen being produced after this exposure in the direction of the arrow f to a length equal to the semidiagonal of an element of the screen and the sensitive surface that is uncovered being again exposed for 2 minutes; there would thus be obtained partial and different lIl'.' solations of the sensitive surface; Fig. 6 represents the combination of the elements constituting the 3 images; the elements succes-- sively insolated once, twice, or three times,

i. e., for 2, 4, or 6 minutes, being represented respectively by black elements, elements with cross-hatching, and elements with simple hatching.

The movements of the cross-ruled screen thatare necessary to obtain this result may be obtained by employing the mechanical device, in accordance with the invention, that is shown in Figs. 7 to 9.

There will be arranged in front of the sensitive surface a cross-ruled screen 5 of the form'shown diagrammatically in Fig. 5, for

example. This screen will not be made up of two or more plates of glass suitably ruled and applied against each other, but, on the contrary, it Wlll be constituted by a single, exceedingly plane glass, this surface being protected simply by a thin colorless varnish, the whole so that this screen may be brought into contact with, or rather to a very slight distance from, the sensitive surface '7. If the normal exposure necessary to obtain as complete as possible a positive at one time is one of four minutes, an exposure will be made, with the cross-ruled screen, for two minutes, after which the grating will be displaced in the direction of the arrow 7 (Fig. 5) to a length m equal to theside of one of the elements, so as to substitute the transparent elements, of the grating for the opaque elements, i. e., in such manner as to obtain the shuttlngofi of the sensitive surface everywhere where it had originally been uncovered and to produce the exposure of this surface where it had originally been shut off. After having proceeded, under these conditions, to make a second exposure of six minutes, we shall obtain, upon development, an image made up of the juxtaposed elements of two images which have been difi'erently insolated and which will represent, by their combination, the totality of the image.

The circular displacement of the screen about geometric centers of the transparent points of the screen, to different amplitudes, and the exposure for different periods of the portions alternately uncovered, would make it possible to obtain an image which would be the resultant of the images formed by the different displacements of the cross-ruled screen.

The transverse displacement of the cross ruled screen in its plane would also make ject by monochrome tones of proportional values. For that purpose there would be employed a panchromatic sensitive surface, and a first exposure would be made while placing in front of the objective a colored screen suitable for the selection of one color; the cross-ruled screen would then be displaced and a second exposure would be made while placing in front of the objective a colored screen suitable for the selection of another color, and so on, so as finally to obtain on the panchromatic surface the impression of the different colorings of the subject.

The screens are generally made up of elements of small dimensions; the number of elements to a centimeter is about 50 in the most usual cases, and in that case'the side of one of these elements would then be of a millimeter, so that the displacement of the cross-ruled screen for the purpose of sitive plate, so as to render possible the modification of the position of the screen during the exposure.

The device hereinafter described makes it possible to produce the displacement of the cross-ruled screen in all directions, the orientation. of the displacement, as well as its amplitude, being adjustable from the outside and the different positions of the cross- I ruled screen in relation to its'original position being controlled from the outside. It also makes it possible instantly to transform the rectilinear displacement of the screen into a circular. displacement about geometric centers of the transparent elements of the screen.

Referring particularly to Figures 7 to 9, a grating-carrying frame 8 is displaced by rolling on balls 9 arranged at each of its corners; these balls rest against a frame 10 which guides the displacement of the frame 8 in a vertical plane and makes it possible to displace the said grating-carrying frame in a direction parallel to the luminous rays either in one direction or in the other. The grating-carrying frame 8 bears attachment pieces 11 in the form of a right-angled el-. bow; these attachment pieces are fastened to the. frame 8 and arranged so as to maintain the regular distance apart of the two I frames 8 and 10 and the balls 9 which perunit the frame 8 to be displaced by rolling on the frame 10, so that the displacement of the grating-carrying frame may be-obtained in all directions and in all convenient amplitudes. j

It "has, besides, two plates 12 including, on the one hand, two centered axles '13 which are able to rotate in theholes bored in'the framework 14, and, onthe other hand,

. spindles 15 which may be rendered eccentric and which are integral with the bearings 16, the latter being movable and adjusta-ble in the diametral grooves of the plates 12 by means of the screws 17 having milled knobs 18.' Two set screws 319 are adjustable against the bearings'16 and make it possible to render the bearings 16 immovable in a determined position.

The plates 12 carry disks 20,,o'n .which divisions in degrees are marked, making it possible to regulate the orientation of the plates by bringing the suitable divisions opposite fixed pointers 21 integral with the the cups merely allow very slight framework. Suitable set screws 22 which are mounted in the said framework and adjustable against the plates make it possible to render the plates 12 immovable in any position whatever.

Angular displacement or rotation of the plates 12 may be insured by a single control,

which consists of two worm gears 23 keyed on the axles of the plates and engaglng with two worms 24 keyed on a counter-shaft 25, the rotation of which is effected either by a wheel for manual operation 26, keyed to one of its ends, or by any motive element not shown.

Two systems of pantographs for the screen frame are composed of the

levers

27, 28, 29, 30, 31, 32, which are assembled on the'bearings 16 and on axes; these'systems ofpantographs are articulated about fixed axes 33 integral with the frame work 14. The grating carrying frame 8 is attached to the axes 34 by means of yokes 35 which are attached'to the frame and which carry in their forks rollers with semicylindrical' grooves 36, the latter being arranged to roll on the axes 34, thus making possible the horizontal displacement of the frame 8 when the guide frame 10 is displaced in the direction of the luminous rays in order to bring the grating nearer to the sensitive surface or more it further away therefrom. Adjust able screws 37 for the axes 34have two cups into which there are placed the balls 38 -which rest in the cups of the brackets 39 integral with the frame work.- This arrangement is utilized for the purpose of pre'venting possible bending of the axes 34 under the weight of thegrating-carrying frame 8; la in order to make it possible for the rarhe 8 to assume its very slight displacement when it .is desired to displace the cross-ruled screen.

I The apparatus is provided with two systems of amplifying pantographs composed of the

levers

40, 41, 42, 43, 44, 45, assembled on the spindles .15 and on axes, these systems of pantographs being 'articulated on fixed axes 46 integral with the frame work. The

levers

44 and 45 of each system of pantographs are assembled by means .of an axis having a suspension pivot 47 which supports the stirrup-shaped support 51 integral with a rim 50 (Fig. 8). Owing to the stirrupshaped support, this rim is suspended 1n equilibrium; Within the rim there isrotatrbly mounted a disk 49 which supports a be oriented in any direction, an orientation The operation of the device 1s as follows.

If we are concerned with obtaining the displacement of the cross-ruled screen, along a rectilinear orientation, it will sufiice to adjust the orientation of the plates 20 by bringing the suitable divisions opposite 1ndicating pointers 21, and then to adjust in a parallel direction the orientation of the diaphragms 48 and of the sights 52 in agree ment therewith, and the displacement of the cross-ruled screen will be obtained, under the conditions desired, by manual operation of the milled knobs 18. The pointers 53 of the diaphragms will indicate, on an enlarged scale, the amplitude of the displacement. It is merely necessary that the graduatlons be made on a suitable scale.

movement of the spindles 15 to the gratingcarrying frame 8 have been established for a reduction of five times, and if the pantographs of transmission of the movement of the spindles 15 to the diaphragms 48 have been established for an amplification of five times, the amplitude of the displacement of the gratingwill be indicated enlarged 5X5=25 times by the pointers 53 of the diaphragms 48 on the divisions of the sight 52;

If we are concerned with obtaining the circular-displacement of the grating about geometric centers of the transparent elements, it will suflice to render the spindles 15 eccentric by manual operation of the milled knobs 18 and to produce the rotation of the spindles 15 by manual operation of the hand wheel 26; the amplitude of the circular displacement of'the grating will be indicated, asbefore, on the sights 52 by the pointers 53 of the diaphragms 48.

What I claim is: 1. The method of making negatives from which printing plates may be produced which consists in making successive expo- .sures of a sensitized surface part at least a thereof through a screen and moving said screen in its own plane during said exposures in a. path defining a closed figm e.

2. The method of making negatives from which printing plates may be produced which consists in making successive ex-' posures of a sensitized surface through a screen and moving said screen in its own 1 plane in a circular path during said exposures.

' The method of making negatives from which printing plates may be produced For example, if the pantographs of transmission of the.

which consists in making successive exposures of. a sensitized surface at least a part of said exposures being made through a screen and moving said screen during exposure in a circular path in its own plane.

4; The method of making negatives from which printing plates may be produced which consists in making successive exposures of a sensitized surface through a screen and moving said screen during exposure in its own plane in circular paths, the amplitude of the path of movement for each exposure differing from the amplitude of the paths of movement for the other exposures.

5. The method of making negatives from which printing plates may be produced which consists in making an exposure of a sensitized surface, thereafter making successive exposures of the same sensitive surface through across ruled screen and moving said screen during exposures about the geometriccenters of the elements of the grating of the screen said moving being effected in the plane of the screen and at different amplitudes for each exposure.

6. The method of making negatives from which printing plates may be produced which consists in'making successive ,exposures of asensitized surface through a screen and moving said screen during exposures in its own plane and in circular paths of different amplitude for each exposure, said exposures being of relatively different duration.

7. In combination, a screen and a holder 100 therefor disposed within a camera and means for moving the holder in a closed path in the plane of the screen.v

8. In combination, a screen and a holder therefor disposed within a camera, and 105 means arranged outside of the camera and operatively connected with said holder for moving the latter in a circular .path in the plane of said screen. g

9. In combination, a screen and a holder 1 0 therefor disposed within a. camera, means for supporting the holder, and additional means outside of the camera and operativelyv connected to-said first means for controlling the amplitude of the displacement of the 1 5 holder and screen in circular paths in the plane of the screen. I

10. In combination, a screen and a holder therefor disposed within a camera, means outside of said camera and operatively connected with said holder for effecting continued circular displacement of screen about the geometric centers of the transparent elements of the grating of the screen the displacement being in the plane of said screen, and additional means cooperating with said first means for modifying the amplitude of displacement.

11. In combination, a cross ruled screen and a holder therefor disposed. within a camera, .pantographic means disposed outside of the camera and having a part thereof projecting into the camera to support the holder, driven means for operating the pantograph comprising an adjustable spindle operatively connected to said pantographic means whereby the holder may be moved in the plane of the screen and in a circular path about the geometric centers of the transparent elements of the screen grating.

12. In combination, a and a. holder therefor tlisposed within a camera, pantographic means pivoted within the camera and operatively connected with the holder to support the latter, the said means projecting at one end to the outside of the camera, an adjustable connection to receive the free end of said pantographic means, means for rotating said connection holder in a path of circularmovement and j to cause the pantograph to orient the said a control for the pantographic means or adcross-ruled screen justing the amplitude of such circular path I i with respect to the geometric centers of the transparent elements of the screen-grating. 13. A pantographic controlfor the screen holder of a camera comprising a system of levers, a fixed bearing therefor, means for imparting movement to said levers to cause the holder to move with the screen in circular'paths in its own plane.

' 14. A pantographic control for the screen holder of a camera comprising a system of levers operatively connected to said holder at one end, an adjustable revolving support -for the opposite end of said system of levers,

anda second pantographic control operatively connected to the first/system and the revolving support to adjust the amplitude of circular displacement of the screen with respect to the geometric centers of the transparent elements of its screen grating.

In testimony whereof I affix my signature.

LAURENT BASSA'NL