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Nov. 20, 1953 J. A. BOYAJEAN, JR 2,575,546 MACHINE FOR PRODUCING SCREENED RELIEF PATTERN PLATES Filed July 24, 1948 4 Sheets-Sheet 1 (<1) (b) 2 E 3x q u E g 5 ‘L _\ s_/> 23 43 70mar/5027MP5 FIG] JOHN A. EOYAJEAN,J€ INVENTOR. ATTORNEY Nov. 209 1951 Filed July 24, 1948 J. A. BOYAJEAN, JR 2575546 MACHINE FOR PRODUCING SCREENED RELIEF PATTERN PLATES 4 Sheets-Sheet 2 INVENTOR. JO H N A. BOYAJEAN/(T': {1% @mm ATTORNEY Nov. 20, 1951 J. A, BOYAJEAN, JR 2,575,546 MACHINE FOR PRODUCING SCREENED RELIEF PATTERN PLATES Filed July 24, 1948 4 Sheets-Sheet 3 4bFIG. - INVENTOR JO N A. BOYAJ J"\.. NJ; {3W ATTORNEY Nov. 20, 1951 Filed July 24, 1948 J. A. BOYAJEAN, JR 2,575,546 MACHINE FOR PRODUCING SCREENED RELIEF PATTERN PLATES 4 Sheets-Sheet 4 uOm uOm 9% o¢m z gm Em: mwijas0é 5.62% gm mmwh SmEwr=?im2< Ar ¢m\mo.¢o_ 0.591b$-°0.26“;0m?1 mEuCbw 31Hmyu5wm:aslzj13sz 9U]0 ‘ "M 59Q0ozm. mm mow |_v \2 mt 0K E mm .W hF M h m /\ Wn? [._|Jl JoHN A WV maV0mmTE“A B Mb ATTORNEY isatentecl Nov. .20, 1951 2,575,546 UNITED STATES PATENT OFFICE 2,57 5,546 MACHINE FOR PRODUCING SCREENED RELIEF PATTERN PLATES John A. Boyajean, Jr., Upper Montclair, N. J ., as signor to Fairchild Camera and Instrument Corporation, a corporation of Delaware Application July 24, 1948, Serial No. 40,594 27 Claims. (01. 178—6.6) 1 This invention relates to machines for pro ducing screened relief pattern plates and, while it-is of general application, it is particularly adapted for producing on a decomposable plate a 2 high speed rotating cutter or chipping or goug ing tool. With this type of apparatus, the tool generally leaves small burrs or other irregulari ties over the face of the plate which seriously half-tone reproduction of any reproducible image 5 interferes with obtaining satisfactory reproduce sheet, which plate is suitable for further repro tions. Furthermore, the metal plates used in’ duction of the image by printing or like duplica such machines are generally heavy, costly, and ting processes. di?icult to ship and are easily damaged by im . In the reproduction of images, such as photo proper handling. graphic prints or negatives by printing or like 10 Furthermore, the automatic machines for duplicating processes, it has been customary to A forming such half-tone plates heretofore pro produce half-tone engravings, that is, engraving posed have been complex and cumbersome in plates having a “screen” structure composed of operation and have been dif?cult to maintain in a series of regularly spaced dots, by photo-chemi accurate adjustment, which is necessary to pro cal processes. In such half-tone plates, the aver age size and spacing of the dots in each incre mental portion of theplate vary proportionately with the average shade value or greyness of the 15 cure half-tone plates of reasonable cost and satis factory quality. It is an obJect of the present invention, there fore, to provide a new and improved machine for producing screened relief pattern plates _ corresponding portion of the image. The sur faces of these dots lie in the original plane of the 20 which obviates one or more of the above-men plate and receive the printing ink from a roller tioned disadvantages of the prior-art machines or the like. of the type described. Such half-tone plates and their method of It is another object of the invention to provide manufacture are well known in the art, so that a new and improved machine for producing - no detailed description is required here. HOW 25 screened relief pattern plates which achieves one ever, it is also well known that the process of or more of the following advantageous char making such photo-engravings involves elaborate acteristics not hitherto realized: virtual elimina and expensive equipment and a large number of ’ tion of skill or technique in operation of the steps, each of which must be performed with machine; substantial reduction in time required great care and skill in order to obtain a satisfac 30 to form a plate; ability to form a number of tory half-tone plate. Such skill is generally plates simultaneously; extreme accuracy of re acquired only by extended apprenticeship and production of all image shades; elimination of all artisans of the required skill are frequently un chemical and photo-chemical processes; pre available. All of the foregoing factors contribute determination of the desired contrast range, that to ‘the high cost of such half-tone plates and to is, range ‘from full white to full black; and a sub the time required for their completion. stantial reduction in the weight of the formed _ Heretofore there have been proposed various. plates. machines and apparatus for automatically and In accordance with one feature of the inven mechanically forming half-tone plates repre tion, there is provided a machine for producing sentative of an image to be reproduced. such 40 on a plate from an image sheet a screened relief machines have generally included a support for pattern suitable for image reproduction by print an image sheet, a support for the plate to be ing processes comprising a ?rst cylinder for sup formed, and mechanism for scanning the two porting a plate, a second cylinder for supporting supports synchronously. The image sheet scan— an image sheet, and means for rotating the ner. has‘ included a photoelectric pick-up, the 45 cylinders synchronously. The machine further output of which is ampli?ed electrically and comprises a ?rst reciprocable carriage including utilized to actuate some type of plate-cutting or an electro-optical pick-up system disposed for deforming tool carried by the plate scanner. An scanning an image sheet on the second cylinder, interrupter is included at some point in the sys a second reciprocable carriage including a plate tem' .to produce the screen structure. In one 50 deforming tool disposed for scanning a plate on; previously proposed arrangement, the plate the first cylinder, means responsive to the output deforming tool is in the form of a heated stylus of the pick-up system for actuating the plate-7 acting on a plate of decomposable material but, deforming tool, and means for reciprocating the; in general, such proposed machines have utilized carriages synchronously. The machine also in-_v metal plates-and the‘ deforming tool has been a 65 cludes an electrical screen generator including a‘ 2,575,546 4 3 rotor element driven synchronously with said cylinders and an independently rotatable stator, printing processes. By the term “image sheet," and means for rotating said stator at a speed of a lower order of magnitude than said rotor ele meant any sheet carrying _an optical representa ment, the output of said generator being con nected to modulate the output of said pick-up photographic positive or negative print, a photo graphic transparency, either positive or negative, or the like. By the term “screened relief pat tern,” as used herein and-intheapp'en‘d'ed claims, system. ,7 a . ‘_ n as used herein and in the appended claims, is tion of the image to be reproduced, such as a 5 In the preferred'embodiment of the invention, is meant a pattern in which regularly spaced por tions of the surface are removed, the area of the the engraving machine optionally includes other desirable features, among which are the follow ing: the electro-optical pick-up system includes a light source and a source of puisatnigfqgnegc of screen frequency, such as the ,screenggener removed portions in any elemental portion of the print varying with the shade values of the corre sponding elemental portion of the image to be ator, connected for modulating such light source; ‘reproduced, the_be'st known example of such in order to form on the plate an inverted image .A a screened relief ‘pattern being the half-tone photo-“engraved ‘plate. By the term “printing of that on the image sheet, the pi‘ckliip'syst'e‘m processes,” as used herein and in the appended carriage and the tool carriage are driven by aten claims, is meant any process by which a plate sioned inelastic belt, one of the carriages being carrying a screened relief pattern may be uti adapted to be locked to one run of the belt and the other being provided with a releasable clamp , lized to produce multiple reproduced images, of which the most usual example is the'conventional to-enga'ge the otherrun of the belt; further, the. printing process. tool vcarriage comprises a tool-‘actuating as The machine of vFig. 1 includes plate andeimage sembly carrying the ‘plate-deforming tool and sheet supports, speci?cally,v a cylinder Hlon which means for biasing theitool' assembly into engage is supported or secured in any suitable mannera ment with the plate-cylinder; the tool assembly plate ll of deformable material ‘and .a "second cylinder I2 on which is supported or secured :an also includes an adjus'tahbl'e shoe engaging a plate on- the plate cylmdervfor vdetermining the image sheet [3. By the term “deformablerma~ , terial” is meant a material that ‘may :be cut, In accordance with another feature er a pre ferredfo'rm of the inventiom'a machine of the 30 gouged, decomposed or otherwise deformed byan - engraving tool or stylus tovform an imageeree type described includes means for adjusting the neutral position of thetool. system substantially independentlyto' adjust the maximum deformation of the “plate, correspond producing plate. The .plate and vcylinder as sembly H), Il may be of any suitable type-but preferably is of the'type-describe'd and claimed in applicant's copending application, Serial No. 40,595, ?led concurrentlyherewith. The image sheet I3 for use‘in the machine speci?cally :de ing to the white level of‘ an image sheet. scribed hereinafter is :a :photographic positive output of the "screen. generator to adjust the minimum deformation of .theépl'ate, correspond ing to the black level of an ‘image sheet, and means-foradjusting-the output of the pick-up 35 print. "Another feature of the-preferred form of the invention comprises means'for biasing the plate 40 The machine ‘of Fig. 1 includes ‘means-for rotat ing the cylinders 10 and 12 synchronously and deforming tool to an inoperative position, a nor preferably isochronously. Speci?cally, this fro mally excited electromagnetic’means for retain tating means includes a-common shaft for the ing thetool in an operative. position, and means two cylinders including portions “(1,441) coupled responsive to the failure ‘of the source of periodic by a disengageable coupling i5. The coupling l~5 screen potential, such as the screen generator, includes a notched disc l5arand, a complementary for actuatingthetool to ‘an inoperative position. For a better’ understanding of the present in vention, together withother'andfurther ‘objects thereof, reference is had to the following descrip tion taken in connection with the accompanying drawings, vand its scope will bepointe'd out in the appended claims. . ' ‘Referring now to the drawings, Fig. 1 ‘is-a schematic perspective ‘of ‘a machine for produc ing ‘on a plate from ‘an image ‘sheet ‘a screened relief pattern suitable for image reproduction by printing processes; Fig. 1a is a chart to aid in ex plahation of the ‘operation of "the ‘machine of Fig. 1; Fig. 2 is a fragmentary view, partly in sec‘ tion,» of therplate-defo'rming tool assembly ofthe machine of Fig. 1 together with an associated stroboscopicivie'wer; Figs. 3a and 3b are ‘sche matic perspective views of the tool-actuating mechanism in its neutral position and ‘one ex treme position, respectively; Figs. 4a and 4b are top plan and longitudinal 'elevational views, re spectively, of the machine'represented in Fig. 1; while Fig. 5 is a schematic electrical circuit ‘dia gram of the various electrical and electronic com ponents of the machine of Fig. 1. disc [517 provided with a pin .l'5c_adap_ted accu ‘ rately to engage the notch of disc l5a when these discs are moved axially by a lever "l5dto effect engagement of the coupling. This pin-type coupling ensures engagement'of the two Jshaf-t portions Ma, Nib in a predetermined phase rela tionship so that they rotate isochronously. The shaft Ilia is connected to‘ be ‘driven by a motorlt‘ which may be of anyfsuitable type, althou'ghifa number of machines are to be operated in 'Pmuli tiple, as described hereinafter, the motor must be of the synchronous type. The ‘driv-ingwcon nection from the motor iii-to the shaft Mar-in: cludes a ?exible ‘coupling ll ofranysuitabl'e type which mechanically ?lters or smoothesaout ‘any pulsation characteristic ‘of the ‘driving. motor 16. This driving connection further includes a'worm i8 and engaging worm‘ gear l9 vvand anovér=run=~ ning or one-way drive‘clutchi?, ‘the driving ele ment of vwhich is connected to gear [9 'an‘d:the driven element of 'whichisconnected-to shaft'l‘da. On the drive shaft kid is aheavy‘?'y "wheel ‘21 which ensures pulsationless rotation'of 'theisha'ft 70 Ma, léb and the cylinders I'O'an'd l'2‘regar'dless of irregularities which :might otherwise ‘result from the characteristics of the motor icon-lin drawings, there is illustrated ‘schematically a perfecti'ons 'in the ‘drivingsgears. The overertnr-v machine ‘embodying the invention for produc Referring now more particularly to Fig. l'of the , ning clutch 2B, which-may‘be'of'anyconventional ing on‘ a ‘plate ‘from ‘an image sheet‘ a screened rcllefpattern suitable for 'imagereproduction by ' type, 'serves two purposes: ('1) itallows'l‘the??y 5 2,575,548f wheel 2| to decelerate normally upon de-cner glzation of the driving motor I6 without impos ing an undue back load on the speed-reducing gears 18,19 and (2) it permits manual rotation of the cylinders ill and i2 during mounting of the respective plate ii and image sheet l3 thereon, free of the driving gearing. The machine of Fig. 1 also includes means, such as a reciprocable carriage 22 including an electro-optical system, for scanning an image sheet l3 on its supporting cylinder [2. The elec tro-optical scanning system is shown schemati cally as including a light source 22a having an _.-; The tool-actuatingv assembly-30 also includes means for biasing the tool to an inoperative posi tion.~ To this end, the assembly 30 is mounted on a platform 34 which is pivoted on the carriage 23 as by a pivot pin 35. About the pivot pin 35 is secured a stiff helical biasing spring 36 with extending portions acting on the platform 34 and carriage 23 to bias the carriage 33 for pivotal movement in a clockwise direction about the pivotpin 35. Secured to the under side of the carriage 23 is an electromagnet 31, for which the pivoted platform 34 acts as an armature. As de scribed hereinafter in connection with the circuit diagram of Fig. 5, the electromagnet 31 is nor mally excited to attract the platform 34 and re tainthe shoe 32 and the tool 24 in an operative relation with respect to the cylinder [0 and plate only diifused re?ection, that is, the angle of I l. The tool-actuating assembly 30 also includes incidence of the axis of optical system 22b at the electromagnetic means connected to respond to image sheet i3 is not the same as the angle of 20 the output of the electro-optical pick-up system re?ection of the axis of the optical system 2211. 22a-22d for actuating the tool 24. This electro The machine further includes means, such as a magnetic actuating means is shown more clearly reciprocable carriage 23 including a plate-de in Figs. 3a and 3b, while its connection to the forming tool 24, for scanning a plate H on its electro-optical pick-up system is described here supporting cylinder ill. By the term “plate-de 2: inafter with reference to the complete circuit forming tool,” as used herein and in the appended diagram of Fig. 5. optical system 221) and a photocell 220 provided with an optical system 22d including an aperture stop to limit its ?eld of view to an elemental area of the image sheet i3 and is disposed to receive claims, is meant a tool capable of deforming a The machine of Fig. 1 further includes a source plate II as by cutting, gouging, indenting, there of periodic pulsating potential or current, spe mally decomposing, or the like. In the preferred ci?cally, an electrical screen generator 40 driven embodiment of the invention, the tool 24 is a synchronously with the cylinders 10 and I2 and heated stylus for thermally decomposing incre 3 Q. connected to modulate the output of the pick-up mental areas of the surface of the plate II, as described hereinafter. The carriages 22 and 23 reciprocate on parallel longitudinal guide rods 38 and 39. There is further provided a mechanism for reciprocating the carriages 22 and 23 in opposite directions to form a laterally inverted screen system 22a—22d for producing a pulsating ex citation of the actuating means 30 at a screen frequency. Speci?cally, the generator 40 in cludes a toothed rotor element 40a, mounted on and driven by the shaft 14a, thus eliminating any-back-lash in the drive of the screen genera~ tor and ensuring absolute accuracy in the spac ing of the screen dots. The generator also in relief pattern on plate li. This mechanism in cludes a pair of spaced pulleys 25 and 26 and a is cludes. an independently rotatable toothed stator tensioned inelastic belt, such as a steel tape 21, element 401). The teeth of the elements 40a and supported on the pulleys. Tensioning of the tape 40b are equally spaced about the outer and inner 21 is effected by a stiff helical spring 28 joining peripheries thereof, respectively, the number of its two ends. The pulley 25 is driven from shaft teeth in each being determined by the desired [4a through double worm gearing 46, 41 and 48, 49, the gear ratio being preferably so chosen} 45 “screen.” For example, if a 12G-screen plate is desired, each of the elements 40a and 40b will that the pulley 25 makes one revolution for the have 120/\/2 teeth within an angle of rotation complete normal range of travel of the carriages corresponding to a peripheral travel of the stylus 22 and 23. One of the carriages, preferably the 24 of one inch on the plate i i. The elements 40a carriage 23, is adapted to be locked or secured (by means not shown) to the lower run of the 50 and 40b are electrically insulated from each other tape 21, while the other carriage 22 is provided with a releasable clamp disposed to engage the and are connected in an electrical circuit to form the two elements of a condenser, as described hereinafter in connection with the complete elec upper run of the tape 27 and including a man trical'system of the machine. ually operable element or knob 29, by which the carriage 22 can be released from the tape 2‘! to 55 . There is also provided means for rotating the permit adjustment of the carriage 22 independent stator element 401) at a speed of a lower order of magnitude than the rotor element. Speci?cally, of the carriage 23 upon disengagement of the pin there is provided a speed-reducing means between coupling 15. This adjustment is provided to the shaftv Ma and stator element 431). This means permit accurate registration of the electro-optical system of the carriage 22 with an image sheet 60 includes a pulley 41 mounted on a shaft 42 sup porting the stator element 3%. Driving the pul l3 on the cylinder i2 when initially setting up the ley 4 l- is an endless belt 43 passing around a pair machine. The carriage 23 includes a tool-actuating as of guide pulleys 44 and a return pulley 45 dis sembly 3G for driving the plate-deforming tool posed so that the upper run of the belt 43 is 24. As shown in Fig. 2, the assembly 30 includes 65 parallel with the path of movement of the car means for determining its neutral position with riagez23. The belt 43 is connected to be driven respect to the plate H on the cylinder ill. This by the carriage 23 as by a connection 43a, as means is in the form of a resilient hairpin 3! shown, and includes a tensioning spring 46 on having one arm secured to the assembly 30 and the return side of its connection 43a. Adjust carrying at the end of the other arm a shoe 32 70 ment of the speed ratio may be determined by disposed to engage a plate I l on the cylinder Ill. selection ‘of the diameter of pulley 4! relative The separation of the arms of the hairpin 31 may to the lead of the carriage 23. The overall re be adjusted to adjust the neutral position of the duction is such that the speed of the stator ele shoe 32 by means of a thumb nut 33 threaded in ment 40b is a small fraction of the speed of the the other arm of the hairpin 3|. 15 cylinders wand l2. If a plate is desired in which 23,575,846“ 7. 8 the angle oi.’ the screen lines v‘is 45". as iscus tom'ary, the speed of the stator element '40!) is that Jfraction of the speed of- the-cylinders “land 12 such that the stator 40b rotates an angular distance equal torone tooth and space during the time that the cylinders l0 and I2 ‘makeitwo com plete revolutions. I .The details of construction vof-lthe stylus actu ating mechanism 30 are best shown in'th'e 'sche matic perspective views, partly inisection,>of Figs. 3a and 32). As shown, th‘e'magne'tic circuit of iéthe mechanism-30 is formed by two spaced opposed C-magne'ts 30a and Y391). symmetricallyldi'sposed in the air gaps formed between the opposed legs of the C-‘ma'g'nets 30a. and 30b is a vane-like mag netic armature 36c about either endfo'f Whichlare disposed the actuating windings 30c and 3011, thus providing a balanced electromagnetic actu ating'mechanism. ' upon an elemental area of the plate ll being examined. The lamp '65 is-connected to a cir cuit for exciting it from the periodic source or screen generator 453, as described hereinafter. Referring now to'Fig. 5 of the drawings, there CI is represented a circuit diagram, partially sche matic, of the electrical system of the apparatus of Fig. 1, corresponding elements being identi?ed by'the same reference characters. Starting with 10 the pick-up photocell 220, this is represented as a ‘device of the conventional electron multiplier type, in which the several multiplier cathodes 229 are connected to electrically spaced points on a voltage-divider resistor ‘55 connected between ground and the negative terminal of a unidirec-v' tional source connected to loadresistor plied by way -—B. The anode of the cell 22c is a suitable source +13 through a ‘H, the signal across which ‘is ap of a coupling condenser l2 to the In Fig. 3a the armature 30a is shown in the 20 input terminals of a photocell ampli?er 13, unexcited or neutral position, while 'inlFig. 31) it which may be of any suitable well-known type. is 'shown in one limiting actuating position cor The output terminals of the ampli?er ‘T3 are responding to maximum excitation of 1the wind~ connected to supply the ampli?ed signal across ings 30c and GM of one polarity. extension a load resistor A low-pass inverse-feed-back of armature 35a is connected ‘to the stylus 24 '- network l5, constituted for example by a series which is loosely supported for reciprocation in a resistor 15a followed by a shunt condenser 15b, projection '30:!‘ of the casing 39. Surrounding-the is connected from the output terminals of the stylus 24 is a noninductive heater 56 connected ampli?er '73 through a coupling condenser ‘it to to/and supported by terminals .51. 'Theccasing of the input terminals thereof for eliminating the thevmechanism '38 comprises a permanent mag 30 effect on the output signal of variations of the net'structure in which the side plates-130f and 30g mean brightness of an image sheet on the mean are permanent ‘magnet elements, while the end position of the stylus 2/12. As well understood in plates complete their magnetic circuit through the C-members 30a and 38b. The armature ‘30c is mounted on a tension shaft 36h, rigidly sup ported ‘from the casing. In Figs. 3a and ‘3b the dotted lines indicate the-paths of the permanent magnet f?ux in the two positions of ‘thea'rmature member, while the dash lines representthe paths of ?ux due to the actuating windings 30b and'3llc. The actual physical construction of ‘one ‘em bodiment of the apparatus represented :in Figs. the ‘art, such an inverse or negative feedback of the low frequencies reduces the gain of the ampli?er at such frequency to a very small value without appreciably affecting its response to the high-frequency components of the signal gen erated by the photocell 220. The periodic source of generator 40 is con nected to modulate the output signal of the pick up system developed across the load resistor 14. 1 and 2 is shown in Figs. 4a. and 4b in which cor responding‘ elements are identi?ed ‘by the same reference characters. Brie?y, ‘the whole appa ratus is mounted'on a base or bed plate so, the To this end, the generator 5i] is connected as a variable condenser in the input circuit of a screen ampli?er unit ‘ii; speci?cally, the rotor is con nected to ground while the stator is connected to a source of polarizing voltage +B through an gearing l8, l9 and cent, the pulley '25, the fly isolating resistor ltd. The output of amplifier wheel 2i, and the screen generator iii) being ren llis coupled through a condenser 18 to an addi closed within an end housing 5i . tional ampli?er unit ‘39, the output of the ampli The actuating mechanism 383 is enclosed within a housing .52 ?er 19 being connected through a coupling con mounted on carriage 25, while theelectro-op'tical denser Bil to a load resistor 8| provided with an pick-up system is disposed within a housing :53 adjustable tap or connection-82. The signal at. mounted on carriage 22. The-pin clutch, ‘1.5 is the tap 82 is applied to a scanner light ampli fier 84, which is power amplifier for generating disposed within a central bearing support 154 which includes the pin clutch l5 and-its operating 55 a periodic current synchronous with the periodic potential developed by the generator Ail. The lever Had. The unit 54 also includes electrical current output of the ampli?er 84 is connected to switches and control members for the ‘electrical system of the machine described hereinafter. modulate the light source 22a of the pick-up sys The pulley 25 and the bearing for the right-hand tem; speci?cally, the lamp 22a may be connected end of the shaft lrlb are disposed in an .end 60 directly in the output circuit of the amplifier 84 to be excited thereby. housing 55. It will be understood, however, that the details of this mechanical construction and A second load resistor 85 is included in ‘the arrangement may be varied within wide limits outputcircuit of ampli?er l9 and provided with to suit individual special requirements. an adjustable tap 86 from which a selected por Referring speci?cally to Fig. 2 of the drawings, tion of theoutput signal is applied to a strobe there is shown associated with the cylinder in light. ampli?er 8?, which is also a power ampli?er and plate It a stroboscopic viewer forzinspecting ford'eveloping a periodic current pulse synchro a plate while it is undergoing deformation. This nous with the periodic potential generated by generator #9. ' The gaseous discharge lamp 65 viewer includes a portable microscope 60- dis posed on a support iii adjustably pivoted ‘at 62 of vthe stroboscopic vieweris connected directly on a base $3 and thus adjustable for focusing-on a plate H. The microscope ?ll is included within an enclosing housing: 64 which also includes a stroboscopic light source, suchas a gaseons‘lamp in the output of the ampli?er 8i. - Inorder to permit a ready adjustment of th maximum and minimum penetrations of a plate ' l i ‘being deformed by the stylus 213 in accordance 65and an optical system'??ifor iocusi-ng'the light *78 'with the maximum and minimum shadevalues': 2,575,546 of the image being reproduced, there is provided a circuit for combining an adjustable portion of the output of the screen generator 40 with an adjustable portion of the output from the photo cell 220 to energize the actuating mechanism 30. To this end, the output of the ampli?er TI is ap plied also through a coupling condenser 88 to a load resistor 89 having an adjustable tap 90. The load resistor ‘I4 of the ampli?er ‘I3 has an adjustable tap 9I and the taps 90 and BI are interconnected through isolating resistors 92 and 93 and a switch I05, the junction of resistors 92 and 93 being connected to an isolating ampli?er 94 which, in turn, is connected to a power ampli 10 tacts I I9 of a relay I 20. The relay I 20 is con nected in the anode circuit of a vacuum-tube ampli?er I2I, the control electrode of which is connected to the output circuit of ampli?er ‘l9 and includes a conventional grid leak I22 and grid condenser I23. The relay I20 and ampli?er I2I are adjusted so that the relay I20 maintains its contacts closed whenever normal potential is sup plied from the screen generator 40 through the ampli?ers ‘I1 and 19. Thus, the elements I20, I2! constitute means responsive to the failure of the source, speci?cally, to the failure of rota tion of the generator 40, for interrupting the con ‘trol circuit II2, which de-energizes holding ?er 95, the output of which is connected through 15 magnet 31, permitting the biasing spring 36 to a power transformer 96 to the serially connected actuate the tool 24 to inoperative position. windings 30c and 30d of the stylus actuating The contacts I I9 of relay I20 complete a circuit mechanism 30. In case it should be desired to to the holding magnet 31 of the actuating mech operate the machine of the invention from a sep anism 30 through a resistor I24 and a rectifying arate synchronized source of image signals from 20 device such as a contact recti?er I25, the wind a local or remote source, there may be provided ing 31 being by-passed by a condenser I26. Con a voltage divider I03 having an adjustable tap nected between the buses I I I and I I2, immediate I04 and connected to the source or supply ter ly following the oif-on switch I I3, is a current minal I06 at which such signals appear. The transformer I21, the primary winding of which switch I05 may then be operated selectively to 25 is connected in series with a constant-current connect with the tap I04 or the tap 9|. ballast tube I28. The secondary winding of trans In series with the windings 30c, 30d is a drop former I2? is connected directly to the heater 56. ping resistor 91 having an adjustable tap 98, Following the contacts II6 of the safety switch, while across the secondary winding of transformer the motor I6 is connected between the buses III 96 is connected a voltage-divider resistor 99 hav 30 and I I 2. While the motor I 6 may be of any suit‘ ing an adjustable tap I00. The taps 98 and I00 able type, it is shown as a split-phase condenser are interconnected through isolating resistors motor of the hysteresis synchronous type, having WI and I02, the junction of which is connected one winding IBa connected directly between the back to the input circuit of the power ampli?er power buses and a second winding IBb connected 95. From the tap I00 is derived a signal potential 35 therebetween through a phase-splitting con which varies with, and is a fraction of, the denser I29. At this same point, a power recti?er potential across the actuating windings 30c, 30d, unit I30 is connected between the buses III and while from the tap 98 is derived a potential vary H2. The unit I 30 may be of any conventional ing with the signal current through the windings. type for converting the alternating-current sup These two signals are combined and fed back ply to a unidirectional current of required oper to the input circuit of ampli?er 95 as an inverse feedback for linearizing the overall character istics of the ampli?er 95 and actuating mech ating potentials, indicated collectively by the reference +B. Coming now to the operation of the apparatus described and referring ?rst to the mechanical impedance of ampli?er 95 to obtain a desired 45 operation of the apparatus of Fig. 1, it will be degree of damping of the actuating mechanism seen that initially a plate to be engraved or de 30. The unidirectional sources for the several formed is mounted’ on cylinder I 0 in any con ampli?er units of the circuit of Fig. 5 are repre venient manner, as by the method described in sented collectively as +B, although the sources of applicant's aforesaid copending application, Se the several ampli?ers may be of different potential 50 rial No. 40,595. The pin clutch I5 is disengaged values according to the tube types and circuit and the image sheet is then mounted on cylinder constants of each ampli?er. It will be under I2 in any suitable manner. For this purpose, the stood that each of the several ampli?ers de carriage 22 may be unclamped from the belt 21 scribed may be of any suitable conventional type by means of the release knob 29. The carriage of one or more stages, as required. 55 22 may then be adjusted longitudinally to obtain The general electrical power circuit for the proper registration , of the pick-up system system is represented at the top of Fig. 5. Power 22a—22c with the image sheet. The pin clutch I5 for the unit as a whole may be conventional is then engaged to ensure a direct driving connec-4 60-cycle, l10-volt power applied to the input ter~ tion between the shaft portions I 4.41 and I4?) and minals H0. The lower terminal I I0 is connected 60 further to ensure correct phasing of the cylinders to a bus III common to the power and control I 0 and I 2. mechanisms hereinafter described. The upper The cylinders I0 and I2 may be manually ro terminal I I0 is connected to a control line II2 tated by virtue of the slip clutch 20 and the through a manually operable off-on switch H3; mechanism may be operated until the stylus 24 9. pair of limit switches I I4 and H5 disposed in 65 registers with a margin of the plate to be en the path of travel of carriages 22 and 23 (not graved. The stroboscopic viewer shown in Fig. 2 shown) for interrupting the electrical circuit is then disposed to obtain a microscopic view of in case either carriage reaches its limit of travel; the elemental area of the plate II in registry the normally open contacts I I 6 of a safety micro with the stylus 24 and, with the electro-optical switch mounted on the platform 34 and adapted 70 system in operation as described hereinafter, the to be closed initially by manual operation of the deforming or decomposing of the plate II by the tool-actuating assembly 30 to operative position stylus 24 is observed when the electro-optical to complete a holding circuit for electromagnet pick-up system views the darkest and lightest 31; normally closed contacts of a push button portions of the image sheet to be reproduced. stop switch I I8; and the normally closed con 75 Adjustments of the electrical system are then anism 30 and for effectively controlling the output 2,575,546 i2 I 1’ 40 is‘so proportioned to the constantsof' thev‘actu ating means 39 that the following relationships made, as described hereinafter, to obtain the ap propriate minimum and maximum penetrations of the plate H‘ by the stylus 24 corresponding to the darkest and lightest shade values present in are satis?ed: I - ' - (1) The mean penetration of the plate H ‘the image sheet, respectively. , C1 by the tool 2A; is of the same order of magnitude as the neutral separation of the tool and the The cylinders It and F2 and their associated plate. ‘mechanism are then operated manually to place the eIectro-optical pick-up system at the starting corner of the image to be reproduced. The elec trical system is then put in operation and is ef fective automatically to cause the electro-optical pick-up system 'to scan the image sheet in a ‘spiral path and simultaneously to cause the stylus 24 to scan the’plate II. While the cylinders H} I (2) The amplitude of the pulsating excitation from the screen generator it is so proportioned to the response of the electro-optical pick-up system that the minimum penetration of the tool, corresponding to one shade extreme in the image, for example, black, is of the order of 1/5 of its maximum penetration, corresponding to. the and l2' are effectively on. a common shaft, so other shade value, for example, white. that they rotate isochronously in the same di rection, the carriages "22 ‘and 23 move at equal (3) The rotational spee'd‘of the cylinders l6 and I2 is so related to the frequency of excita tion from the screen generator 46 that the pee ripheral travel of the plate cylinder it during one period of the screen-frequency excitation‘ is approximately twice the line spacing. For ex ample, if it is desired to produce a 120-line half— tone plate, the cylinder iii should travel 1/ 60\/2 inch during one period or cycle of the screen speeds ‘in opposite directions, due to the fact that they are clamped to opposite runs of the tape 21, as described above. The result is that the image reproduced on the plate H is laterally inverted withv respect to the image sheet, so that when it visv turned over it will reproduce the image in its correct relation. - > Rotating simultaneously with the cylinders H1 25 and I2 and‘ at the same speed is the rotor element 46a‘ of the screen generator 45. This generator, as described hereinafter, is effective to modulate the light source 22c of=the electro-optical sys tem and the constants of the system are selected so as? to procure substantially complete modula tion, that is, so that the‘ light source 220. is sub stantially completely‘ extinguished at the fre-' quency of the screen "generator. The output of the'photocell 220 is thus likewise modulated‘ and, after ampli?cation and the suppression of the unidirectional component, is applied as a signal modulated'carrierwave to thel'windings 36c and 30d of. the actuating mechanism’ 30. This excita tion‘of the windings 30c and 30d causes the stylus . to oscillate about‘its "mean or neutral position at the frequency of the signal developed by the vscreen‘ generator All, while the amplitude of the ‘oscillation is varied or modulated in accordance withgthe amplitude of the signal developed by ' ' frequency. v The foregoing relationships are represented in Fig. 1a, in which the line b represents the devele opment of the surface of plate I 1, while the line ('1. represents the relative path of travel of the ' neutral position of the tool 24. In this figure, curve 0 represents one cycle of screen frequency modulated to minimum amplitude corresponding to a black shade in the image being-scanned, while curve (1 represents another cycle of the screen frequency modulated at maximum ampli tude corresponding to a white portion of the pic ture being scanned. The relative dimensions of the various parameters of one machine embody; ing the invention are represented in Fig. 1a and it will be seen that these relative dimensions sat isfy the ?rst two of the foregoing relations; that is, the excursion of curve 0 below the line b, rep resenting the minimum penetration of the stylus, is approximately one-?fth the ex‘ - cursion of curve (1 below line 1), represent ‘the photocell 226' which, in turn, varies with the ing the maximum penetration of the stylus, shade- values in the successive incremental areas while the mean value of these two excursions is of the same order of magnitude as the separation of the lines a and b representing the neutral separation of the stylus and the plate. It will also be seen that, since the unidirectional component of the modulated signal is suppressed so that only a pure alternating current signal is applied to of the image sheet being scanned. As stated vabove, the‘ plate If is preferably of a decom posable material, such' as cellulose nitrate, while r the stylus 24 is heated to a temperature of the order of 1200-” F. by the heater 55 so that, as it ‘oscillates into contact with the plate H, the stylus removes portions of the plate by thermal decomposition; forming pits of depth and sur face. area- varying with the amplitude of the os cillation of‘ the stylus 24" and‘thus with the varia tions in the shade value of the image sheet. As jaresult, there is formed on the surface of the plate H the equivalent of a half-tone structure comprising a series of elemental dots separating gieries of. pitsv formed by the oscillating stylus . vF'or proper image reproduction, the screen structure of the plate II should, for the lightest shade presented in the image being reproduced, contain a complete series of dots or islands sep arating the pits but of minimum area. Con— versely, when scanning the‘ darkest portion of the image sheet, a complete series of pits of the windings of the actuating mechanism 3t, only ' the negative half of each cycle of screen frequency is effective to actuate the tool 24 into penetration of the plate H. Therefore, the surface of plate‘ 1 I on cylinder ill must travel a distance equal to the spacing of adjacent lines in the‘ period from the commencement of one negative half cycle effective to form a pit of one line to the successive negative half cycle effective to form the next pit. This satis?es the third relation ship above. Turning now to Fig. 5 of the drawings, there will be taken up the operation of the electrical system of the machine of Fig. 1. In order to place the machine in operation, the on-off switch H3 is initially closed. This energizes the heater 56 through the current transformer l2? and the heaters of the various electron ‘tubes. With the limit switches H4, H5 normally closed and after a reasonable warm-up time, the tool actuating minimum surface area should be formed. In order to secure this result, certain adjustments of the ‘electrical system are made, as described hereinafter, to ensure that the amplitude of the assembly 30 is manually lowered to operative pulsating excitation from the screen generator position. contacts H6 are closed, and the motor 2,675,546 14 I6 is placed in operation to drive the various mechanical elements of the machine of Fig. 1, including the screen generator 4%. Simultaneous following speci?cations of one machine con structed in accordance with the invention and providing satisfactory operation: ly, the power recti?er I30 is energized and sup plies at its output terminals +B suitable uni directional potentials for the several ampli?ers of the system. When the apparatus has reached normal speed and the power recti?er is in opera tion, the screen generator 40 is effective to de velop a periodic potential of the desired frequency which is ampli?ed in the units 11 and ‘I9 and ap plied to the grid of ampli?er tube l2l. Initially tube I2! has zero bias and is fully conductive, energizing relay I20 to hold open its normally closed contacts. However, when the screen-fre quency signal is applied to the grid of tube I 2|, it is self-biased by grid recti?cation substantially to cut-off de-energizing relay I20 to close its contacts H9. Up to this time, the platform 34 must be held down manually. Upon the closing of contacts H5 and H9, however, the electromag net 37 is energized with unidirectional current through the recti?er I25. The electromagnet then attracts its armature 34 to hold the actuat ing mechanism into engagement with the plate Screen _______________ __ 65 lines per inch Screen frequency _____ __ 350 cycles per second Speed of cylinders Ill, I2 . 50 R. P. M. Lead _________________ _. l/65\/§ Mesh ________________ l- 65V? Stylus 24 _____________ _. Radial to cylinder Stylus taper angle _____ _. 75° Thus, there is provided by the invention a ma chine for producing on a plate a screened relief pattern from an image sheet which virtually eliminates all skill or technique previously re quired to produce half -tone engravings. Further more, the machine of the invention produces such plates in only a small fraction of the time required for conventional photo-engravings. For example, it has been found possible to produce a plate 8 x 10" of 65 screen in eighteen minutes. The machine is capable of extreme accuracy of reproduction of intermediate shade values be tween full black and full white. At the same time, all chemicals and necessary facilities for H on cylinder I 0. The machine is now in full handling them are eliminated. By the use of the operation for forming an image on the plate H. stroboscopic viewer as described, it is possible to As stated above, initially the tool 24 is op determine in advance the desired contrast range erated to a margin of the plate H for forming a test pattern on such margin, while observed by 30 of the resultant plate. This is in marked con trast to the conventional chemical processes the stroboscopic viewer, as shown in Fig. 2. The which generally require repeated trials before the neutral position of the tool 24 is adjusted by ad desired contrast range is obtained. Further, by justing the shoe 32 by the knob 33 (Fig. 2) to the the simple operation of switch Hi5 of Fig. 5, it desired relation, as represented in Fig. la. In is possible to adapt the machine of the invention view of the fact that the output of the screen to operation from image-representing signals re generator 40 as ampli?ed in units ‘H, 19, and 81 ceived by radio or wire from remote synchro is applied to the gaseous discharge lamp 65 of the nously scanned sources. stroboscopic viewer, this lamp illuminates in syn While there has been described what is at pres chronism with the lamp 22a of the electro-opti cal pick-up system, so that the elemental portion 40 ent considered to be the preferred embodiment of the invention, it will be obvious to those_skilled of the plate ll being viewed is illuminated only in the art that various changes and modi?cations for brief intervals synchronous with the peaks of may be made therein without departing from the the modulated screen frequency, this is, with the invention, and it is, therefore, aimed in the ap points of maximum penetration of the tool 24. pended claims to cover all such changes and As is well understood in the art, the observer modi?cations as fall within the true spirit and thus obtains an apparently stationary view of scope of the invention. the minute portion of the plate penetrated by the What is claimed is: tool 24. 1. A machine for producing on a plate from an Initially the minimum penetration or defor mation of the plate is adjusted to correspond to ” image sheet a screened relief pattern suitable for image reproduction by printing processes com the black level or darkest shade in the image prising: a ?rst cylinder for supporting a plate; sheet being scanned. This initial adjustment is a second cylinder for supporting an image sheet; made by tap 99 of voltage divider 39 which ad means for rotating said cylinders synchronously; justs the minimum amplitude of the screen-fre quency signal ampli?ed and applied to the actu 55 a ?rst reciprocable carriage including an electro optical pick-up system disposed for scanning an ating mechanism 35. This adjustment may be image sheet on said second cylinder; a second made substantially independently of the signal from the electro-optical pick-up system, since reciprocable carriage including a plate-deform ing tool disposed for scanning a plate on said ?rst able fraction of the amplitude of the signal from 60 cylinder; means responsive to the output of said pick-up system for actuating said tool; means the screen generator 4!]. for reciprocating said carriages synchronously; The pick-up system is then adjusted to a por an electrical screen generator including a rotor tion of the image of maximum brightness, for element driven synchronously with said cylinders example, white, and the tap SI of the voltage divider ‘M in the output of the ampli?er 73 is then 65 and an independently rotatable stator; and means for rotating said stator at a speed of a adjusted to obtain the desired maximum pene lower order of magnitude than said rotor ele-_ tration in accordance with the relationships of ment; the output of said generator being con Fig. 1a. The operation of the system with the nected to modulate the output of said pick-up switch Hi5 connected to the external source of image signals N16 is in all respects the same, it 70 system. 2. A machine for producing on a plate from an only being necesary that such signals be derived image sheet a screened relief pattern suitable from a pick-up system, either local or remote, for image reproduction by printing processes operating synchronously with the pick-up car comprising: a ?rst cylinder for supporting a riage 22 of Fig. 1. By way of example only, there may be given the 75 plate; a second cylinder for supporting an image that signal for black shade levels is an inappreci 15 259255546 is sheet; ‘means for rotating said cylinders; a ?rst reciprocable carriage including an electro-optical pick-up system disposed for scanning an image sheet on said second cylinder; a second recip rocable carriage including a plate-deforming tool disposed for scanning a plate on said ?rst cylin der; means responsive to the output of said pick up system for actuating said tool; means for reciprocating said carriages synchronously; . an electrical screen generator including a rotor ele- ‘ nected to modulate the excitation of said lamp synchronously with the scanning of the image sheet. 6. A machine for producing on a plate from an image sheet a screened relief pattern suitable for image reproduction by printing processes comprising: a ?rst cylinder for supporting ‘a plate; a second cylinder for supporting an image sheet; means for rotating said cylinders syn chronously; a ?rst reciprocable carriage includ ment driven synchronously with said cylinders and an independently rotatable stator; and means for rotating said stator at a fraction of ing an electro-optical pick-up system disposed system. synchronously; said pick-up system including a light source; a periodic potential generator of for scanning an image sheet on said second cylin der; a second reciprocable carriage including a the speed of said cylinders equal to oneéhalf the plate-deforming tool disposed for scanning a ratio of the speed of said cylinders to the screen 15 plate on said ?rst cylinder; means responsive to frequency; the output of said generator being the output of said pick-up system for actuating connected to modulate the output of said pick-up said tool; means for reciprocating said carriages 3. A machine for producing on a plate from an image sheet a screened relief pattern suitable for image reproduction by printing processes comprising: a ?rst cylinder for supporting a plate; av second cylinder for supporting an image Sheet; means for rotating said cylinders iso chronously; a ?rst reciprocable carriage includ ing an electro-optical pick-up system disposed for scanning an image sheet on said second cylinj der; a second reciprocable carriage including a plate-deforming tool disposed for scanning a plate on said ?rst cylinder; means responsive to the output of said pick-up system for actuating said tool; means for reciprocating said carriages isoohronously; an electrical screen generator in cluding a rotor element driven directly by said screen frequency; and a power ampli?er for gen erating a periodic current synchronous with said periodic potential and connected to modulate said light source synchronously with the scan ning of the image sheet. 7. A machine for producing on a plate from an image sheet a screened relief pattern suitable .ior - image reproduction by printing processes comprising: a ?rst cylinder for supporting a plate; a second cylinder for supporting an image sheet; means for rotating said cylinders syn chronously; a ?rst reciprocable carriage includ ing an electro-optical pick-up system disposed for scanning an image sheet on said second cylin der; a second reciprocable carriage including a shaft and a rotatable stator element; and a plate-deforming tool disposed for scanning a speed-reducing gear connected to plate on said ?rst cylinder; means responsive drive ' said stator from said shaft; the output of said gen erator being connected to modulate the output of said pick-up system. 4. A machine for producing on a plate from .' to the output of said pick-up system for actuat ing said tool; means for reciprocating said car riages synchronously; said pick-up system including a gaseous electrical discharge lamp; a sheet; means for rotating said cylinders syn- - periodic potential generator of screen frequency; and 'a power ampli?er for generating a periodic current synchronous with said periodic poten— tial and connected to excite said lamp syn chronously with the scanning of the image sheet. chronously; a ?rst reciprocable carriage includ '- .8. In a machine for producing on a plate from an image sheet a screened relief pattern "suitable for image reproduction by printing processes comprising: a ?rst cylinder for supporting‘ a plate; a second cylinder for supporting an image ing an electro-optical pick-up system disposed an image sheet a relief pattern suitable for image for scanning an image sheet on said second reproduction by printing processes and including a pair of synchronously rotatable cylinders for in dividually supporting a plate and an image sheet and a pair of reciprocable carriages individually cylinder; a second reciprocable carriage includ ing a plate-deforming tool disposedfor scanning a plate on said ?rst cylinder; means responsive to the output of said pick-up system for actuating said tool; means for reciprocating said carriages synchronously; said pick-up system including a including a pick-up system and a plate-deform~ ing tool for respectively scanning said image sheet cylinder and said plate cylinder, a mecha light source; and a-source of pulsating current of 55 nism for reciprocating said carriages synchro screen frequency connected to modulate .said nously in opposite directions to obtain an in light source synchronously with the scanning of verted relief pattern comprising: a pair of spaced the image sheet. ' " ' ' pulleys; a tensioned inelastic belt-supported on 5. A machine for producing on a plate from an said pulleys; one of said carriages including image sheet a screened relief pattern suitable 60 means for looking it to one run of said belt and for image reproduction by printing vprocesses a releasable clamp on the other of said carriages comprising: a ?rst cylinder for supporting'a disposed to engage the other run of said belt. plate; a second cylinder for supporting an image 9. In a machine for producing on a plate from sheet; means for rotating said cylinders-syn; an image sheet a relief pattern suitable for image chronously; a ?rst reciprocable carriage includ 65 reproduction by printing processes and including ing an electro-optical pick-up system disposed , for scanning an image sheet on said second cylin a pair of synchronously rotatable cylinders for individually supporting a plate and an image sheet and a pair of reciprocable carriages in dividually including a pick-up system and a plate der; a second reciprocable carriage including a plate-deforming tool disposed for scanning a plate on said ?rst cylinder; means responsive to 70 deforming tool for respectively scanning said the output of said pick-up system for "actuating image-sheet cylinder and said plate cylinder, a said tool; means for reciprocating said carriages mechanism for reciprocating said carriages syn synchronously; said pick-up system including a chronously in opposite directions to. obtain an gaseous electrical discharge lamp;- and‘ a source inverted relief pattern comprising: ‘a pair of of- pulsatingl'current. ofscreen frequency 30011;‘ , spaced~pulleys;_.a tensioned steel tape supported 2,576,546 _ 17 on said pulleys; one of said carriages including means for locking it to one run of said tape and a releasable clamp on the other of said carriages disposed to engage the other run of said tape. 10. In a machine for producing on a plate from an image sheet a relief pattern suitable for image 18 a pair of sychronously rotatable cylinders for in dividually supporting. a plate and an image sheet and a pair of reciprocable carriages individually including a pick-up system and a plate-deforming tool for respectively scanning said image-sheet cylinder and said plate cylinder, a positioning and reproduction by printing processes and including actuating mechanism for said plate-deforming a pair of rotatable cylinders for individually sup tool comprising: a tool actuating assembly includ porting a plate and an image sheet and a pair of ing a plate-deforming tool; means for determm reciprocable carriages individually including a 10 ing the neutral position of said tool assembly; pick-up system and a plate-deforming tool for electromagnetic means connected to respond to respectively scanning said image-sheet cylinder the output of said picK-up system for actuating and said plate cylinder, a common drive shaft for said tool; and means for producing a pulsating said cylinders including a disengageable coupling; excitation of said actuating means at a screen a mechanism for reciprocating said carriages 15 frequency; the speed of‘ said cylinders being so synchronously in opposite directions to obtain an related to the frequency of saw. excitation that inverted relief pattern comprising: a pair of the peripheral travel of said cylinders during one spaced pulleys; a tensioned inelastic belt sup period 01‘ said excitation is approximately twice ported on said pulleys; one of said carriages in the desired llne spacing. cluding means for looking it to one run of said 20 14. In a machine for producing on a plate from belt and a clamp on the other of said carriages an image sheet a relief pattern suitable for image disposed to engage the other run of said belt and reproduction by printing processes and including releasable to permit independent adjustment of a pair of synchronously rotatable cylinders for said other carriage upon disengagement of said individually supporting a plate and an image coupling. 25 sheet and a pair of reciprocable carriages inci 11. In a machine for producing on a plate from an image sheet a relief pattern suitable for image vidually inclucnng a pick-up system and a plate deiormlng tool 101' respectively scanning said; reproduction by printing processes and including plate cyllnder and said image-sheet cylinder, a a pair of synchronously rotatable cylinders for positioning and actuating mechanism for said individually supporting a plate and an image 30 plate-aelorming tool comprising; a tool actuat sheet and a pair of reciprocable carriages in ing assembly including a plate-deforming tool; dividually including a pick-up system and a plate— means I01‘ biasing said tool assembly into engage deforming tool for respectively scanning said ment with said plate cylinder; said tool assembly image-sheet cylinder and said plate cylinder, a including an adjustable shoe engaging a plate on positioning and actuating mechanism for said said plate cylinder for determining the neutral plate-deforming tool comprising: a tool actuating position of said tool; electromagnetlc means con assembly including a plate-deforming tool; means nected to respond to the output of said pick-up for determining the neutral position of said tool system for actuating said tool; and means for assembly; electromagnetic means connected to producing a pulsating excitation of said actuating respond to the output of said pick-up system for ~10 means at a screen frequency. actuating said tool; and means for producing a 15. A machine ror producing on a plate from, pulsating excitation of said actuating means at an image sheet a screened relief pattern suitable a screen frequency; the amplitude of said pulsat for image reproduction by printing processes ing excitation being so proportioned to the con comprising; plate ,and image-sheet supports; stants of said actuating means that the mean means including an electro-optical pick-up sys penetration of a plate by said tool is of the same tem'for scanning an image sheet on its support; order of magnitude as the neutral separation of means including a plate-deforming tool for scan said tool and its plate. ning a plate on its support synchronously with 12. In a machine for producing on a plate from said ?rst scanning means; means responsive to an image sheet a relief pattern suitable for image the output of said pick-up system for actuating reproduction by printing processes and including said tool; a periodic electrical screen generator a pair of synchronously rotatable cylinders for connected to modulate the output of said pick-up individually supporting a plate and an image system; and means for adjusting the output of sheet and a pair of reciprocable carriages in said generator to adjust the minimum deforma dividually including a pick-up system and a tion of said plate corresponding to the black level plate-deforming tool for respectively scanning of an image sheet. said image-sheet cylinder and said plate cylinder, 16. A machine for producing on a plate from a positioning and actuating mechanism for said an image sheet a screened relief pattern suitable plate-deforming tool comprising: a tool actuating for image reproduction by printing processes assembly including a plate-deforming tool; means 60 comprising: plate and image-sheet supports; for determining the neutral position of said tool means including an electro-optical pick-up sys assembly; electromagnetic means connected to tem including a light source for scanning an respond to the output of said pick-up system for image sheet on its support; means including a actuating said tool; and means for producing a plate-deforming tool for scanning a plate on its pulsating excitation of said actuating means at 65 support synchronously with said ?rst scanning a screen frequency; the amplitude of'said pulsat means; means responsive to the output of said ing excitation being so proportioned to the re pick-up system for actuating said tool; a peri sponse of the pick-up system that the minimum _ odic electrical screen generator connected to penetration of said tool corresponding to one modulate said light source; and means for apply shade extreme in said image is of the order of 70 ing an adjustable portion of the output of said one-?fth its maximum penetration corresponding generator to said tool actuating means to adjust to the other shade extreme. the minimum deformation of said plate corre 13. In a machine for producing on a plate from sponding to the black level of an image sheet. an image sheet a relief pattern suitable for image 17. A machine for producing on a plate from reproduction by printing processes and including 15. an image sheet a screened relief pattern suitable 194 for image reproduction ‘by‘printing processes: comprising: plate and image-sheet supports; means including. an-electro-optical pick-upsys-v 20 a. second ampli?er‘ coupled to saidlgeneratoryi means for combining. the outputs ofisaidrv amplie ?er's; meanslresponsive to said combined ‘outputs; for actuatingssaidf tool; means for adjustingthe. tem including a light source for scanning an image‘ sheet on its support; means including a 5 output of said generatorampli?er-to;adjust-the plate-deforming. tool- for scanning a plate» 0n~its1 minimumv deformation of said plate corresponding. support synchronously with“ said ?rst scanning» to theblack- level of an. image- sheet; andimeans for‘ adjusting the output. of said ‘pick-up system ampli?er to adjust the maximum deformation of said.plateucorresponding to the‘: white level offan. image sheet. 22.. Amachineior producing‘ona'.platefrom an. image sheet a. screened ‘relief pattern suitable‘ for image reproduction by printing processes‘ com: an image sheet a screened relief pattern suitablefor image» reproduction byprinting processes 15 prising: plate.- andimage-sheet ‘supports; means including. an electro-optic‘ak pick-up system‘: for comprising; plate ‘and image-sheet» supports; scanning an image sheet on. its support; means means including anelectro-optical pick-up. sysincluding a plate-deforming tool for; scanning. a. tem including a light source for scanning‘. an; plate on its support synchronously with said: ?rst image sheet on its support; means including a plate-deforming toolu-for scanning-a- plate ion. its 20 ‘scanning means ;; means responsive to. the output support’ synchronously» with saidm-?rsthscanning.» of said pick-up system-for actuating said tool; a source of periodic potential connected to modu means;- a ?rstampli?er coupled-to. the outputot _ late the. outputof said. pick-up: system ;:' and means said pick-up. system; - a .periodie'electrical» screen I responsive to the'failure of saidsource for actuat generator; a second # ampli?ercoupled to. said». generator; means for»v combining adjustable por-.. 25 ing said tool to an inoperative position. 23. A. machine for producing. on a plate from tions. of the outputs of said. ampli?ers; :and means means; a ?rst ampli?er coupled vto the output of said pick-up system; a. periodieelectrical» screen generator; a second ampli?er-coupled to= said-10generator; and means responsive~jointly~toithe~ outputs of said ampli?ers for actuating said tool. 18. A- machine'for producing-on arplate'i’rom responsivetosaid-combined outputsior actuating.» an image-sheet a: screenedrrelief pattern suitable said tool. for image reproduction by printing processes-Zoom prising:_ plate and image-sheet supports; means . 1-9. A machine for producing 'on- a platecfrom» an imagesheet a screenedl‘relief patternrsuitable 30 including an electro-ol?tical pi?k-llp System for for image- reproduction. by printing processes. “ scanning an image. sheet on its support; meansin eluding a plate-deforming tool for scanning: a comprising’: plate-‘1 and. ‘image-sheet supports; plate on its support synchronously with said first means including an. electroeopticalv pick-up sys-. scanning means; means for'biasing saidgtool. to an tem for scanning an image‘ sheet on its. support}. means- including a plate-deforming tool for scans. 35 inoperative position; a normally excited electro magnetic means forretainingsaid tool in an op ning a plate on: its support... synchronously. with. erative position; meansresponsive. to the output said ?rst scanning. means;v means responsive: to of said pick-up system for‘ actuating‘ said tool; a the outputof said: pick-up system for actuating source of periodic potential connected to modu said tool; a periodic. electrical. screen generator. late the output of saidpick-up system; and means connected to modulate: thev output: or said-pick-up. responsive, to the failure of said. source for de system; and means. for adjusting the outputof said pick-up system to adjustthe maximum de formation of- said-plate. corresponding touthe.v energizing said electromagneticmeans. forv image reproduction‘ by printingprocesses. comprising-1:’ plate and-l image-sheet» supports ;:v including. an. electro-optical pick-up system for 24. A machine for producing- an a plate. from» an image‘ sheet a screened relief pattern suitable white level of an image sheet. for» image reproduction by printingprocesses com- 20. A- machinev for‘ producingon a. plate from. an image sheet a‘ screened. relief pattern suitable. 45 ‘prising: plate-and image-sheet supports; means means including» an“ electro-opticaler pick-upsys» scanning an image sheet on its support; means includingv a plate-deformingtool for. scanning a plate on its support synchronously withsaid ?rst tem‘ for scanning-van image sheet'on its support;-~ means includinga plate-deformingetool' for scan- <50 scanning means; means including an. ampli?er responsive to. the output of said. pick-up system. ning a plate on-itssupport synchronously-i-wi-thv» for. actuating said tool; a ?lter network coupled said ?rst scanning means; meansresponsive'tcrv to said. ‘ampli?er for eliminating the onset. of the- output of said» pick-up‘ system for actuating variations. of the mean. brightness of. an. image said» tool, a periodic electrical screengenerator- 55 sheet on the mean position of said- tool‘; and a connected to modulate the output of said pick-up» source of‘ periodic potential of screen frequency system; means for adjusting the output of- said connected to modulate‘ the output of‘ said pick’ generatorto- adjust the minimumdeformation of up system. ‘ said plate corresponding to the black-level'of an 25. A'machine ‘for producing on a. plate from~ image‘sheet? and‘ means for'adj'us?ng theoutput’?d an image sheet av screened relief ‘pattern suitable‘ of said pick-up system-substantially- independ» for image reproduction by printing processes com ently to adjust the maximum: deformation ofisaid prising‘: plate and image-sheet supports; means plate corresponding to the- white“ level of an» including an electro-optical' pick-‘up, system'for' image ‘sheet. scanning an image sheet'on itssupport-y means 21- A machine’ for producingon‘ ‘31 platecf'rlom" Bd’includinga plate-deforming tool for scanning a an. image: sheet: a screened relief pattern» suitable - forv image~.1.'eproduction by- printing processes comprising:- plate and image-sheet- supports; means including anelectro-optical pick-up system plate‘ on its support‘ synchronously with said?rst scanning means; means including an amplifier responsive totheoutput of‘ said pick-upsystem actuating‘ said tool’; »a low~passvv inverse feed-back including alight source; for scanning an image mJnetwork coupled to said amplifier-for eliminating sheet‘ on. its support; means. including a plate.» the e?ect of variations of the mean brightness deforming tool. for; scanning. a. plate on-itssupport synchronously with: said; ?rst. scanning: means}, a» of an image sheet on the mean- position' of said‘ tool ;-and a source of periodic potential of screen frsttampli?jer coupled: to the output of said'rpick frequency connected to modulate the output’ of up. systenn: aperiodicelectricalLscreeng generatog: 751‘said-pick-up-system. ~ » 21 9,575,546 26. A machine for producing on a plate from an image sheet a screened relief pattern suitable for image reproduction by printing processes com prising: plate and image-sheet supports; means including an electro-optical pick-up system for scanning an image sheet on its support; means including a plate-deforming tool for scanning a plate on its support synchronously with said ?rst scanning means; means responsive to the output of said pick-up system for actuating said tool; 22 plate on its support synchronously with said ?rst scanning means; means responsive to the output of said pick-up system for actuating said tool; a source of periodic potential of screen frequency connected to modulate the output of said pick up system; a portable microscope adjustable for focusing on a plate undergoing deformation and including a stroboscopic light source; and a cir cuit for exciting said light source from said periodic source. a source of periodic potential of screen frequency connected to modulate the output of said pick up system; and a stroboscopic viewer ior said plate including a light source energized from said source. 27. A machine for producing on a plate from an image sheet a screened relief pattern suitable JOHN A. BOYAJEAN, JR. REFERENCES CITED The following references are of record in the ?le of this patent: UNITED STATES PATENTS Name Date for image reproduction by printing processes com Number prising: plate and image-sheet supports; means 2,063,614 including an electro-optical pick-up system for 20 2,079,970 scanning an image sheet on its support; means 2,179,002 including a plate-deforming tool for scanning a. 2,489,691 McFarlane ________ __ Dec. 8, 1936 Speed ____________ __ May 11, 1937 Washington, Jr. ____ Nov. 7, 1939 Washington ______ __ Nov. 29, 1949