US2092765A

US2092765A - Electric machine

Info

Publication number: US2092765A
Application number: US647884A
Authority: US
Inventors: George E Losier
Original assignee: MARION L LOSIER
Current assignee: MARION L LOSIER
Priority date: 1932-12-19
Filing date: 1932-12-19
Publication date: 1937-09-14
Anticipated expiration: 1954-09-14
Also published as: GB432795A; US2032541A; US2225915A; DE691914C

Description

Sept. 14, 193 7.

Sam/Wm Sc'REEMA/a AMPLIFIER G. E. LOSIER ELECTRIC MACHINE 'Filed Dec. 19, 1932 I mluku 4 Sheets-Sheet l AMPLIFIER 2/2 aw I EEDREE E. LES/EH INVENTOR BY M24, A 7' ATTORNEY Sept. 14, '1937. I s. E. LOSIER 2,092,765

ELECTRIC MACHINE Filed Dec. 19, 1932 4 Sheets-Sheet 3 E5 11 Tm:

EEUREEELUE/ER INVENTOR 614 ATTORNEY G. E. LOSIER ELECTRIC MACHINE Filed De c. 19, 1952 Sept. 14, 1937.

4 Sheets-Sheet 4 EEDREE E. Lus/sR INVENTOR BYW A 34 /155 HIS ATTORNEY Patented Sept. 14, 1937 UNITED STATES PATENT OFFICE ELECTRIC MACHINE Orange, N. J.

Application December 19, 1932, Serial No. 647,884

7 Claims.

The present invention relates to a method and an automatic machine for cutting printing plates or other reproductions from an image, picture or I pattern, and also to the printing plate or reproduction made with and according to the method and machine of the invention.

An object of the present invention is to prothe shape of frustums of pyramids whereby is obtained a printing plate which can be used for making thousands of ,copies of pictures without the mushrooming of such elevations such as occurs with the photo-chemically produced plates, but in which all the advantages of the photo-chemical half-tone are present, including the screen eifect, the oblique rows of printing elevations and so on. I

Another object of the present invention is to provide a half-tone printing plate which can be used with greater pressures and which will have a longer life than the heretofore used photochemically produced half-tone plates.

Other objects and advantages of the present invention will be apparent from the following description of the method, machine and plate of the invention and from the drawings and claims illustrating and describing the same.

The accompanying drawings, forming part of the present application, show, somewhat diagrammatically, an embodiment of the present invention, with alternative forms of certain parts, in which:

Figure 1 is a plan view, somewhat diagrammatic, of an apparatus embodying the invention;

Figure 2 is a section view in elevation, taken along the line 2-2 of Figure 1, looking in the direction of the arrows, and in part cut away;

Figure 3 is a vertical section of a scanning head;

Figure 4 is a diagram of the circuit of an amtaken along the line 6-5 of Figure 5, looking in the direction of the arrows; I

Figure '7 is a bottom plan view of a portion oi! Figure 6, looking from the position of arrows l--'|;

Figures 8 and 9 are, respectively, side and back elevation views of the end of the cutting tool;

Figure 10 is a diagrammatic illustration of a screen-eflect producing unit of the apparatus, including a screening wheel;

Figure 11 is a graph of current against time, showing relative strengths of current used in reproducing light, grey and dark portions of the picture;

Figures 12 and 13, 14 and i5, and 16 and 17 are sets of section elevation and .plan views, respectively, of parts of the cut plate corresponding, respectively, to light, grey and dark portions of the picture, and corresponding, respectively in sets, to the light, grey and dark portions of the plotting of Figure 11; and

Figure 18 is a somewhat diagrammatic view of a screening wheel, in part cut away;

Figure 19 is a diagrammatic view of a scanning tape, alternate in form to the wheel oi Figure 18; and

Figure 20 is a print made with a printing plate made with the apparatus and according to the method of the present invention;

In the drawings a channel shaped bed ill (see Figures 1 and 2) carries a pair of spaced apart bottom rails H, H and a pair of side rails l2, 12, one on, each of the channel sides I3, H, which pairs of rails II, II, and l2, l2 respectively support and laterally guide a picture table I l and a plate table liby means of the bottom rollers l6, l6 and side rollers H, H. Means for moving said tables I4 and I synchronously on said rails l I, I l are provided comprising an arm l8 pivoted at one end to said table it and at its other end to a lever l9 which at an intermediate point pivots on a pin 20 iixed on a side l3 of said bed ill at one end thereof. Similarly an arm 2i pivoted to said table 18 connects to a lever 22 which pivots on a pin 23 at the other end of said bed III. A rigid turnbuckle arm 24 connects levers l9 and 22 in driving relation by means of slides 25 and 2B, which are pivoted one to each end oi said turnbuckle arm 24 and which are fixedly adjustable one in each of the

slots

27 and 28, in the outer ends 01' said levers i9 and 22, respectively. By arranging the distance of said slide 25 from its corresponding pin 20 to be different from the distance of said slide 26 from said-pin 23, the length of the stroke movement of said table l4 can be made to be different from that of said table l5, either greater or less to suit the needs of reductionor enlargement from the picture to the plate, as desired. Obviously, when the reproduction is to unit scale these distances are arranged tobe the same.

Movement of said tables l4 and I5 is secured by means of a motor 30 which drives the slow speed vertical shaft 3| which passes through said bed I0 and drives a Scotch yoke 32 (see Figure 2) which connects with the bottom of said table M in driving relation. The Scotch yoke, a well known form of adjustable mechanical movement, is used on account of its adjustability to secure difl'erent lengths of strokes of movement of said table l4 (and of table l5) to suit various sized pictures to be reproduced. In the present case adjustability of the distance of movement of said table l4 for, each revolution of said shaft 3| is secured through the adjusting screw 33.

Directly over said table I4 is a scanning head 35 for scanning a picture 36 carried by said table l4. Said scanning head 35 rides on the bar 37, mounted transversely across said bed l0 and with its ends fixed to said sides l3, l3, for movement of said scanning head 35 across said picture'36 while said table I4 is carrying said picture 30 longitudinally, the relative movement of said scanning head 35 with'respect to said picture 35 being along a diagonal across said bed 10, in a manner and by means hereinafter fully described. Said scanning head 35 comprises a support bar '40 which rides on said bar 31 and which carries a housing 4| within which is a photoelectric cell 42 which latter faces downward toward said table M, A tube 43, slidably mounted on said support bar 40, extends vertically below said photoelectric cell 42 with its upper end fitting in sliding relation in a short tube 44 connecting with and ex tending downwardly from said housing 4|. Said tube 43 has fixed thereto a rack 45 which engages with a pinion 46 mounted to said support bar 40 and having a thumb-piece (not ,shown) for moving said tube 43 up or down to adjust the position thereof. In its side ach'acent said support bar 40 carries a laterally projecting short tube 41 in which is mounted a condensing lens 48 opposite which, on said support bar 40, is a source of light 49. At the lower end of said tube 43 is a set of condensing lenses 50, and between said lens 43 and lenses 50 is a reflecting prism 5| adapted to reflect light passing thereto from said lens 48 so that it passes through said lenses 50 to a picture 30 on said table M by which it is reflected upwardly back through said lenses 50 through an aperture 52 carried at the upper end of said tube 33 and thence to said photoelectric cell 42. Means for moving'said scanning head 35 on said bar 37 comprise a bevel gear 55, on said shaft 3|, which drives a pinion 56 on a shaft 51 which.

gears 50 drives another set of reduction gears (not shown) in gear box 6| from the upper side of which extends the driven slow speed shaft 62 which carries a belt pulley 63 opposite which latter, on a side i3, is an idler pulley 64. Be-

case of a one to one reproduction, or a predetermined coeflicient thereof in case of reduction or enlargement, for each forward and back stroke of said table I4, that is, for each revolution of said shaft 3|. Mounted on and insulated from said shaft 3| is a commutator 10 having one part cutaway for half the distance around its circumference in which place is set an insulating piece 1|, with brushes I2, 12 hearing on the commutator so that for one half of a revolution of said shaft 3| said commutator 10 makes a circuit between said brushes l2, l2 and for the other half it breaks the circuit. Said brushes l2, l2 connect to the leads l3, 13 one of which includes a source of electric energy 14 for a purpose hereinafter described.

Over said table I5 is mounted a-cutting head in operative relation to a platefll on said table 5, in similar relation to that of said scanning head 35 with respect to said picture 36. Said cutting head 80 rides on a bar 82 mounted to said sides I3, I3, across said bed I0 and receives its motion from a belt 83 mounted on idler pulley 8d and driving pulley 85 which latter connects through a set of interchangeable-reduction gears (not shown) in gear box 86, through a connecting shaft 81 and pinion 88 to said bevel gear 50. Through these driving means, said cutting head 80 will move in synchronism with said scanning head 35 when the latter moves, either in unit ratio for exact size reproduction or greater or less if enlargement or reduction is desired; the ratio being changeable through the gears of said gear box 86, or of gear box 6|, or of gears 60 or any or all of them.

Said cutting head 80 (see Figures 5, 6 and '7) comprises a supporting'rod 90, one end of which rides in looking engagement in the slot 9| in said bar 82. From the other end of said rod 90 there depends a bar 92 having a vertical slot 93 therein in which latter rides a slide rod 94 whose position in said slot 33 is fixed and vertically adjustable by means of the screw 95 which is threaded into said slide rod 96 at its lower end and has its upper end extending through .an

opening in said rod 90 where it has a knurledfixed head 96 hearing against the upper surface said source 14 through said leads 13, I3 in a manner and for the purpose hereinafter described. An armature bar I02, hinged to the lower end of said slide rod 94 through an offset 03, extends vertically upwards and carries at its upper end a transverse bar i04 which extends through an opening I05 in said slide rod 94 and carries an armature I06 in operative relation to said pole piece I00.

Extending oppositely from said bar I04 and fixed to said armature bar I02 is a support bar I01 which supports beneath it a permanent magnet yoke I08, which latter at its outer end carries an electromagnet Hi9 and at its inner ends carries the pole-pieces H0, having therein, respectively, the oppositely facing slots H2, H3. Said field coil I09 is energized by direct current during operation of the mechanism. Clamped one on each side of said pole pieces 0 and I,

by means of the bolts H5 and 5, are the back'.

plate H1 and the front plate H0. Said bolts H5 and H6 also hold between them the oval shaped coil I which extends horizontally edgewise through said slots II2, I I3. Extending centrally lengthwise in the longitudinal opening I26 of said coil I25 is the fiat armature I21 which carries, one at each end, the flexible loops I28, I28, each of which is mounted on one of said bolts H5, H6 which loops I28, I28 allow a small rotative movement of said armature I21 about an axis which is the median of said 0011125. To be actuated by such rotative movement of said armature I21 is avertlcal tool holder I30 which connects at its upper end through a flexible link I3I to said armature I21, said link I3I being flexible in a direction at right angles to said coil I25. At its lower end said tool holder I30 terminates in a chuck I32 which carries a cutting tool I33.

Clamped between a shoulder I34 and an adjustable nut I35 on said tool holder I30 is a flexible annular diaphragm I36 which serves to hold the lower end of said tool holder, I30 and to steady it during movement. Said diaphragm I36 is attached by the four screw bolts I31, I31, near its .edges, to a bar I38 fixed to the bottom of said yoke I08 under the pole piece end and extending outwardly therefrom with an opening I39 therein through which said tool holder I30 passes.

To one side from said tool holder I30, said bar I38 carries 'a vertical guide I through which extends a vertical slide bar I46 which has a longitudinal passageway I41 extending therethrough and carries a horizontal bar I48 projecting therefrom under said diaphragm I36 with an opening I49 therein into or through which said toolholder I30 passes. A longitudinal passageway I50 within said bar I48 connects at its inner end with said passageway I48 and at its other end terminates in a U-shaped opening I5I through the lower face of said bar I48 about said opening I49. In the bottom face of said bar I48 adjacent said opening I5I is another opening I52 which connects with said passageway I50 and which carries therein the supporting roller I53 which is adapted to ride on and to carry the cutting head 80 over a plate 8I to be cut by said tool I33. Means (not shown) for drawing a suction through said passageways I41 and I50 will draw chips cut from the plate and any dirt from under and through said openings I5I and I 52. A brush I54 fixed in said opening I52 and bearing on said roller I53 will wipe oil any chips or dirt adhering to the latter and release them to be carried away by such suction. A gear rack I55 fixed to said slide bar I46 engages a pinion I56 in said guideway I45 which latter carries a spindle I51 which passes through a friction bushing I58 in a wall of guideway I45 and terminates in a knurled head I59. By turning said knurled head I58 to move said pinion I56 on said rack I55, said cutting head 80 can be raised or lowered to suit the length of said tool I33 and to suit the length of the cutting stroke thereof.

In Figures 8 and 9 said cutting tool I33 is illustrated in detail in which the shank I carries at one end the cutting point I66 which has 9 two cutting edges I61, I61 which taper to a point from said shank I65 and for making a plate of a given screen the angle A defined by said edges I61, I61 is predetermined the value of said angle A being smaller for fine screens than for larger ones. The bisecting line of said angle A is at right angles to the plate being cut. The face I68 of said cutting point I66 is cut upwardly and back from the perpendicular -at an angle B to give the tool a bite, the back of the cutting point is cut backwardly from said two edges I61 to give them clearance and in the form here illustrated defines two faces I69, I69. To give bottom clearance,-said cutting point I66 is cut upwardly and back from the tip at an angle C from the horizontal whereby a diamond shaped face I10 is definedin the embodiment of the tool illustrated in Figures 8 and 9.

Referring again to Figures 1 and 2 and others, said photo-electric cell 42 connects to.the aperiodic screening amplifier I (see Figure 4) by the leads I8I and I82, which amplifier I80 comprises two high amplification tubes I83 and I84, which are connected in series with each other and with said photo-electric cell 42, and two power tubes.

I and I86 which are connected in parallel with each other and in series with said tubes I83 and I84, with a resistor I 81 in parallel between said tubes I84 and I85. From the plates of said tubes I85 and I86 a lead I88 connects to one terminal of a screening system I90 and from the grids thereof through said resistor I81 and a source of electric energy I9I the lead I92 connects to another terminal of said screening system I90. The rest of the connections of said power amplifier I80 are conventional, as shown.

Said leads I88 and I92 connect and carry power to a reflecting galvancrneter I83 of the type commonly known in the art as the vibrator element of an oscillograph. The mirror I94 of said galvanometer I93 is in operative relation to a constant source of light I85 and an optical system comprising three condensing lenses 95, 596 and a light slit I91, which latter is arranged to permit a vertical beam of light to be projected by said lenses I96, I86 onto said mirror I98. In operative relation to receive reflected light from said mirror I94 is a second photoelectric cell I88, with a horizontal cylindrical lens I99 between for concentrating the reflected vertical beam from said source I95 into a point at a toothed light interrupting disc 280 positioned between said cylindrical lens I99 and said photoelectric cell I98 and mounted on a shaft 20I (see also Figure 1) which latter is driven by said cutting table I5 through a stud 202, fixed to the latter and connected to a chain 203 (which can be a rack and pinion or other equivalent) through a sprocket 204 and a gear train 205. Analternate to said disc 200 is a toothed ribbon 206 (see Figure 19) which can be driven in back and forth movement by said table I5 and which can be a notched opaque strip or a transparent strip 206 having an opaque portion 201 running lengthwise thereof with one edge describing serrations or a series of uniform notches which come to points at their tops and bottoms like a saw edge.

Said light interrupting disc 200 (also ribbon 206) is opaque and is positioned in relation to said galvanometer mirror I94 so that the light refiected by the latter passes midway between the top and bottom of the notches of the disc 200 as at G in Figures 18 and 19 (at which point the width of the teeth and of the notches is the same) when said photoelectric cell 42 is passing over a portion of a picture which is midway in tone between black and white.

From said photoelectric cell I90 leads 2I0 and 2 connect with the cutting amplifier 2I2 which can be a transformer, resistance or impedance coupled amplifier of types generally well known and its purpose is to amplify the current passed through said photoelectric cell I98 to suflicient strength to operate said cutting head 80. Leads 70 connection at the lower end of said slide rod 94.

2 I3 and 2 I4 connect said cutting amplifier to said coil I25 (see Figures 5 and 6). When a push-pull type amplifier is used the lead 2I5 connects from the source of high potential of the amplifier to the midpoint of said coil I25.

In the operation of the above described embodiment of my invention for making a printing plate from a picture or other'delineament, a picture 36 is place on said table bilaterally within the movement range of said scanning head 35. The said picture 36 can be aligned with the direction of movement of said table I4 or transverse thereto, but preferably for black and white printing it is placed at an angle of about forty-five degrees so that the black (or white) printed dots in adjacent rows are alternate or staggered (see Figures 13, 15 and 1'7 which show sections of the printing plate) whereby adjacent dots of a given shade, black or white, are adjacent only at the corners thereof thereby avoiding continuous bands of black or white of more or less continuous width in the longitudinal direction which produces an optical illusion which detracts'from the desired effect in the picture. The manner of cutting is more fully explained hereinafter.

When a positive plate BI is to be made from a positive picture 36, or a negative printing plate 8| is to be made from a negative picture36, then said scanning head 35 and said cutting head 80 are moved in opposite directions across said bed I; and, if a negative printing plate 8I is to be made from a positive picture 36, or a positive plate BI is to be made from a negative picture 36, then said scanning head 35 and said cutting head 89 are moved in the same direction across said'bed I0.

Said picture 36 and plate 8| being properly placed and fixed on their respective tables I4 and I by suitable means not shown, said scanning -head 35 is brought to lower end of said bar 31 as shown in Figure 1 and the table I4 is moved to the right in Figure 1 far enough for the left hand corner of said picture 36 to be to the right beyond the line of traveler said scanning head 35. If said picture 36 is a positive and a negative plate is to be out then said cutting head 89 is moved to the upper end of said bar 82 in Figure l and said table I5 is far enough to the right to bring the left hand corner of said plate 8I to the right of the line of travel of said cutting head 80. i

The various electric circuits and sources of light are now energized and said motor 30 is set in motion, whereupon'said tables I4 and I5 begin their synchronous rapid forward and backward movements and said scanning head 35 and cutting head 88 commence their comparatively slow movement across the picture 36 and plate 8|, respectively. During forward movement or said table I4 said commutator I8 is in the open circuit part of its rotation and said electromagnet 99 is de-energized leaving said cutting head 80 down in the plate cutting position, and during the backward movement of table I4 the circuit between said source of electric energy I4 and said electro-magnet 99 is closed through said commutator III and said cutting head 80 is lifted out of the plate cutting position. This movement of said cutting head 80, by said electro-magnet 99, v

into and out of plate cutting position is through movement of said armature bar I02 on its hinged Light from said source of light 49 is reflected from a point on said picture 36 to said photoelectric cell 42, the amount of light reaching the latter being proportional tq the degree of light 'dium or normal tone.

or shade at the point of reflection. Likewise the value of the current which flows through said photoelectric cell 42'and "the circuit connected thereto, including said screening amplifier I80 and oscillograph unit I93 is proportional to the amount of light reaching said photoelectric cell 42.

Said galvanometer I93 is nowenergized by current passing through said photoelectric cell- 42 by virtue of light reflected to the latter from said picture 36 on said table I4 and said mirror I94 is deflected at an angle from a predetermined normal energized position in one direction or the other in ratio to the degree of light or shade of the picture above or below the predetermined me- Said angle is zero, of course, when the said photoelectric cell 42 is scanning those parts of the picture 36 which are of medium or normal shade. Said light interrupting disc 20!] is now rotating and entirely cutting ofl successive portions of the light passing from said mirror I94 toward said photoelectric cell I98 whereby the current flowing through the latter and through said coil I25 of said cutting head 89 and the circuit therebetween varies in alternate succession from a minimum in accordance to the dark conductivity of said photoelectric cell I98 when the light is cut ofi therefrom, to a maximum which occurs when light from said mirror passes through the notches of said disc 200. The graph in Figure 11 indicates the changes in value from minimum to maximum of this current as the light is interrupted by said disc 280, and also the time duration of the minimum and maximum current values as determined by the position of said mirror I94 and the path of the light from the latter to said photoelectric cell I98. It is seen that for light portions of the picture the time duration of the maximum value of the current in the graph of Figure 11 is greatest and of the minimum value the least. For the dark" portions the maximum value of the current is of the least duration and the minimum of the greatest duration. For the grey portions the time duration of the maximum and minimum current values are substantially equal.

During periods of the greatest time duration of-the maximum current value said cutting tool I33 will reach its greatest depth in said plate 8| because it will have time to reach further, for although it is actuated into and out of cutting position from several hundred times to several thousand per second, said table I5 and plate 8I are moved ata corresponding speed to give the required number of actuations of said cutting tool I33 per inch of movement of said table I5 and plate 8|, for example, to simulate a sixty-five mesh screen, the number of complete up and down movements of said cutting tool I33 per inch movement of plate 8I will also be sixty-five. The number of actuations of said cutting tool I33 in a given unit oitime depends on the number of interruptions of light made by said disc 200, and, of course, on the mechanical characteristics of the moving parts, for example, of said cutting head 80. An actual working example is in cutting pictures in a Babbitt metal plate at the rate of ten lineal inches per second to simulate a sixty-five mesh screen under which conditions the actuations of said cutting tool I33 are thirteen hundred per second, regard being had for the fact that half of the one second period is used in the forward or cutting movement and half in the return movement of said cutting head over said plate 8 I.

. areas of the horizontal or printing faces of the areas of horizontal or printing surface.

elevations

234, 235 and 233 between said

depressions

23I, 232 and 233, respectively, being directly proportional to the time durations of the maximum value of current at those parts of the current curve in Figure 11 marked, respectively, light,

grey and dark. Face views (also enlarged) of the plate parts shown in Figures 12, 14 and 16 are shown, respectively, in Figures 13, 15 and 17, with the printing faces of the

elevations

234, 235 and 236 blackened in with ink to indicate the relative degree of shading and light on those parts of an image or picture printed from a plate 8| having

elevations

234, 235 and 236 thereor of various The slanting arrows indicate the direction of movement of the cutting tool I33 in going over the plate 8i during the cutting operation. Where the depressions in the plate 8! run in together as Figures 12, 13 and i4, 15 the elevations (234, 235) are in the forms of frustums of four-sided prisms, with the top faces of the frustums forming the ink receiving areas. The

depressions

23I, 232, and 233 have their lower portions (if not all) in inverted four-sided hollow pyramidal contour. Figures 14 and 15, for example, illustrate a section of printing plate of the invention in which the area cut away was equal to the printing area (made up of the faces of elevations 235, 235) which is left. Here the

depressions

232, 232 are in the form of inverted four-sided pyramids. In Figures 12 and 13 the depressions 23I, 23! are in the form of inverted four-sided pyramids which run in together at their bases, the cut-away surface area being greater than the printing area left. In Figures 16 and 17, the form illustrated has the printing area greater than the cut-away surface area. are in the form of inverted four-sided pyramids. In some cases the lateral faces of said

depressions

23I, 232 and 233 are not true planes but can be slightly concave, due to the shape of the energy curve of the current supplied to said coil I25 and the resultant movement of said tool I33 with respect to said plate 8| as the two are moved, the former up and down and the latter horizontally.

The operation of said cutting head to give an average light and shape effect, for example, to compare with that of the picture being reproduced, in several ways as for example, by adjusting the light slit 52 in the scanning head 35; by raising or lowering the cutting head 80 as by thumb adjustment I 59 to adjust the depth of cut; I

by adjusting the median of the angle of movement of the beam of light from the galvanometer mirror I94 with respect to said interrupter 200; by running the whole apparatus faster or slower whereby the depth of cut is shallower or deeper; or by using harder or softer metal for the plate to be cut to control the depth of cut or in various other ways.

' The method and apparatus of the present invention, in addition to use in a unit machine,

' are applicable to use in an arrangement in which the cutting head is at a point distant from the scanning transmission of current from one to the other being accomplished by wire connection or by a radio system, with suitable amplifying units when required and with suitable means for synchronizing the scanning head and the cutting head. In such case a number of cutting heads could be set up in operated relation to one scan- Here again the

depressions

233, 233

ning head and several reproductions made simultaneously. In such case positives and negatives could be made at the same time on different cutting heads governed by the same scanning head.

The print which is Figure 20 of the accompanying drawings was made with a printing plate which was made by the method of the present invention and'by the apparatus illustrated in the drawings hereof and described in the foregoing specifications, as an illustrative embodiment of the apparatus of the present invention. In Figure 20 there are various degrees of shading from pure white to solid black and through the intermediate shades corresponding to the light portions of the plate illustrated in Figures 12 and 13, the grey portions illustrated in Figures 14 and 15, and the dark portions illustrated in Figures 16 and 17 of the drawings. The pure white is shown in Figure 20 in the upright post under the rail on which the figure is leaning, the light shade is shown in the collar of the overcoat held by the figure, the intermediate shade is shown in the shadow which appears adjacent the figures right shoulder, the dark shade is shown in various degrees in the derby hat held by the figure, and solid black is shown in'the derby and also in a portion of the figures hair. i

The engraved plate cut by the machine and according to the methods of the present invention and herein described is claimed in my copending application Serial No. 742,715, filed Sept. 5, 1934, and allowed August 3, 1935.

Having thus described my invention what I claim and wish to protect by Letters Patent is:-

1. In combination with a photoelectrically controlled relief engraving tool, a light-interrupting member. having a given portion thereof movable along a given lineand having a light passage therein in said given portion and of a width which varies in a direction substantially transverse to said line, a light directing galvanometerhaving its light directing element in operable relation to said given portion and mounted to move a beam of light across said given line, means for concentrating said beam of light into a point at that part thereof which passes through said light passage, and a photoelectric cell in operative relation to receive light directed by said galvanometer through said light passage.

2. In combination with a photoelectrically controlled engraving tool, a light interrupter having light-directing and light-interrupting portions arranged alternately along a given line and movable along said given line, said light interrupting portion being of a dimension which varies substantially transverse to said given line, a light-directing galvanometer having its light directing element in operable relationto move a beam of light across said given line, means for concentrating said beam of light into a point at that portion thereof which passes through the light-directing portions of said interrupter and a photoelectric cell in operative relation to receive light passing from said galvanometer to the light-directing portion of said light. interrupter.

3. In a machine for reproducing a given picture on the surface of a printing plate, in combination, a scanning head; a reflecting galvanometer; an aperiodic amplifier connected between said scanning head and said galvanometer; means for directing a beam of light to the mirror of said galvanometer in a plane at right angles to the axis of movement of said mirror; a photoelectric cell in operative relation to receive light reflected from said light directing means by -the mirror of said galvanometer at various positions of the movement of the latter; a light interrupter'adapted to move a succession of light passages and light interrupting portions across the path of light between said galvanometer and said second photoelectric'cell, said light passages being of varying width-across said light path; and an electrically controlled engraving tool connected in controlled relation to said second photoelectric cell.

4. The method of producing cameo relief engraving with a half-tone screen effect from a picture to be reproduced, comprising scanning with a photoelectric cell to produce flow of electric current whose strength varies proportionally to the degree of light and shade of the picture being scanned; operating an engraving tool with a second electric current of constant value; operating on said second electric current with the aid of first said electric current to produce pulsations in the former which vary in time duration proportionately with the degree of light and shade -in the picture being scanned and producing rela-,

tive movement between said engraving tool and a plate to be engraved which is inoperative relation thereto.

5. The method of producing a screen effect printing plate with a tool having two cuttin edges which taper away from each other from a common point and with a photosensitive scanning elementin controlling relation to said tool which comprises synchronously scanning an image with said photosensitive element and moving said tool in successive, parallel paths across a plate to be cut with its said cutting edges in a plane substantially transverse to the direction of movement in said parallel paths, and simultaneously moving said tool in an up and down movement at a given rate in relation to the rate of speed of movement in said parallel paths into successive cutting engagements with said plate to such, depth and in such number in each of said parallel paths of movement that a plurality of substantially tetrahedral cutsare formed which are aligned longitudinally and transversely and which vary in length, width and depth in proportion to the degree of shading of the image beingscanned.

6. In a machine for cutting any given image in reproduced relation into a printing plate with a screen efi ect, in combination, means for scanning an image; a -screen effect producing system comprising a light transmitting galvanometer in controlled relation to said scanning means, a photosensitive element to receive light transmitted by said galvanometer, alight interrupter having a light passage which is tapered and which is substantially transverse to a beam of light transmitted by said galvanometer to said photosensitive element, means for directing a beam of light to said light transmitting galvanometer and for defining said beam of light into a small point at said light interrupter, said light transmitting galvanometer being so related to said other parts of said. screen efiect producing system that said beam of light at its small point is movable along the length of said tapered light passage, and means for causing relative movement between said beam of light at its small point part and said tapered light passage in a direction substantially transverse to said beam of light; and a plate cutting tool which is in controlled relation to said photosensitive element and which has two cutting edges which taper away from each other from a common point.

7. In a machine for reproducing agiven picture on the surface of a printing plate, in combination, a scanning head; a reflecting galvanometer; an aperiodic amplifier connected between said scanning head and said galvanometer; means for directing a beam of light to the mirror of said galvanometer in a plane at right angles to the axis of movement of said mirror;

' a photoelectric cell in operative relation to receive light reflected from said light directing means by the mirror of said galvanometer at various positions of the movement of the latter; a light interrupter adapted to move a succession of light passages and light interrupting portions across the path of light between said galvanometer and said second photoelectric cell, said light passages being of varying width across said light path; a cylindrical lens having its axis substantially in the plane of movement of the light beam reflected from said reflecting galvanometer and to focus the light at said light interrupter; and an electrically controlled engraving tool connected in controlled relation to said second photoelectric cell.

GEORGE E. LOSIER.