US2092764A

US2092764A - Electric machine

Info

Publication number: US2092764A
Application number: US645384A
Authority: US
Inventors: George E Losier
Original assignee: MARION L LOSIER
Current assignee: MARION L LOSIER
Priority date: 1932-12-02
Filing date: 1932-12-02
Publication date: 1937-09-14
Anticipated expiration: 1954-09-14

Description

Sept. 14, 1937. G, E. Lo'slER ELECTRIC MACHINE Filed DSC. 2, 1932 5 Sheets-Sheet 1 SCREEN/NG AMPL/F/ER fxxxxxxix Esa/wss E. Las/:R

INVENTOR YM/4M Afa/A5 4b ATTORNEY Sept. 14, .1937. v G E, LoslER 2,092,764

- ELECTRIC MACHINE Filed Dec. 2, 1932 5 Sheets-Sheet 2 `{SIIIIIIIIIII /0/ -97 /ELD o/L 96 Y f /oo 8315' 7J /ag /09 5/ 55 s /06 C N uw j uw faz /oa [22g 07x L 2 'm8 En/w55 El Las/5R /2/ nl 224 INVENTOR ATTORNEY Sept. 14, 1937. G. E. LOSER 2,092,764

ELECTRIC MACHINE Filed Dec. 2, 1932 s sheets-sheets 55am/ss E Las/ER INVENTOR a ATTORNEY Patented Sept. 14, 1937 UNITED STATES PATENT OFFICE one-fifth to William A. and four-fifths to Marion L.

Orange, N. J.

Hughes, Newark, N. J., Losier, East Application December 2, 1932, Serial No. 645,384

6 Claims.

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

An object of the present invention is to provide a method and machine for performing the steps of the method for making reproductions if images, pictures and patterns such as making half-tone printing cuts or plates directly from the picture without the use of the chemical processes heretofore used.

Another object of the present invention is to provide a half-tone printing plate in which the printing points or elevations are substantially in the shape of irustums of pyramids whereby is obtained a printing plate which can be used for making thousands of copies of pictures without 20 the fmushrooming of such elevations such as occurs with the photo-chemically produced plates, but in which all the advantages of the photochemical half-tone are present, including the screen effect, the oblique rows oi printing elevations and so on.

Another object ofthe 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 t, w the invention and from the drawings and claims 5i illustrating and describing the same.

The accompanyingy 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 l 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;

Figure 3 is an illustration, somewhat diagrammatic, of a screen-effect producing unit of the apparatus, including a screening t-ape;

-7, Figure 4 is a diagram of the circuit of an amplifier used;

Figure 5 is a vertical elevation view in section of the plate cutting head, in place on a plate to be cut, taken along the line 5 5 of Figure 6, looking in the direction of the arrows; Figure 6 is a section view, in part cutaway,

taken along the line B-Ii of Figure 5, looking in the direction of the arrows;

Figure '7 is a bottom plan view of a portion of Figure 6, looking from the position oi' arrows 1 1;

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

Figure 10 is an illustration, somewhat diagrammatic, of an alternate embodiment of a screeneffect producing unit such as is shown in Figure 3;

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 15, and 16 and 17 are sets of section elevation and plan views, respectively, of parts of the out 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, alternate in form to the screening tapes of Figures 3 and 10.

' In the drawings a channel shaped bed I0 (see Figures 1 and 2) carries a pair of spaced apart bottom rails II, II and a pair of side rails I2, I2, one on each of the channel sides I3, I3, which pairs of rails I I, I I, and I2, I 2 respectively support and laterally guide a picture table I4 and a plate table I5 by means of the bottom rollers IE, I6 and side rollers I1, II. Means for moving said tables I4 and I5 synchronously on said rails II, II are provided comprising an arm I8 pivoted at one end to said table I4 and at its other end to a lever I9 which at an intermediate point pivots on a pin 2|] xed on a. side I3 of said bed IIJ at one end thereof. Similarly an arm 2I pivoted to said table I5 connects to a lever 22 which pivots on a pin 23 at the other end of said bed I0. A rigid turnbuckle arm 24 connects levers I9 and 22 in driving relation by means of

slides

25 and 25 which are pivoted one to each end of said turnbuckle arm 24 and which are fixedly adjustable one in each of the

slots

26 and 26 in the outer ends of said levers I9 and 22, respectively. By arranging the distance of said slide 25 from its corresponding pin to be different from the distance of said slide from Said pin 23, the

length of the stroke movement of Said table I4 can be made to be different from that of said table I5, either greater or less to suit the needs of reduction or enlargement from the picture to the plate, as desired. Obviously, when the reproduction is to unit scale these distances are arranged to be the same. Y

Movement of said tables I4 and I5 is secured by means of a motor 21 which drives the slow speed vertical shaft 2S which passes through said bed IU and drives a scotch yoke 29 (see Figure 2) which connects with the bottom of said table I4 in driving relation. The scotch yoke, a well known form of adjustable mechanical movement, is used on account of its adjustability to secure different lengths of strokes of movement of said table I4 (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 i4 for each revolution of said shaft 28 is secured through the adjusting screw 29.

Directly over said table i4 is a scanning head 30 for scanning a picture 3l carried by said table I4. Said scanning head 3B rides on the barV 32, mounted transversely across said bed lil and with its ends xed to said sides I3, I3, for movement of said scanning head 3B across said picture 3| while said table I4 is carrying said picture 3| longitudinally, the relative movement of said scanning head 33 with respect to said picture 3l being along aV diagonal-across said bed IIB, in a manner and by means. hereinafter fully described. Said scanning head 3l! comprises a source of light 33, a condensing lens 33 which concentrates a beam of light from said source 33 at a point on said picture 3l, a photo-electric cell 34 and condensing lens 34 which receives such a beam of light reflected from such a point on picture 3l and concentrates it on said photoelectric cell 34.

Means for moving said scanning head 30 on said bar 32V comprise a bevel gear 35, on said shaft 28, which drives a pinion 35 on a shaft 36 which drives a bevel gear 33 and pinion 31, which latter, through the set of interchangeable reduction Ygears 38 drives another set of reduction gears (not shown) in gear box 39 from the upper side of which extends the driven slow speed shaft 4I! which carries a belt pulley 4I opposite which latter, on a side i3, is an idler pulley 42. Between said pulleys 4I and 42 there extends a belt 43 Vwhich connects with said scanning head 3G by aset screw 43 in driving relation. The driving gear train for said belt 43 is geared down to move said belt 43 at such a rate that said scanning head 3E! is moved the` distance ofthe size of the screen mesh to be simulated in the case of a one to one reproduction, or a predetermined coefficient thereof in case of reduction or'enlargerne'nt, for each for- Ward and back stroke of said table I4, that is, for each revolution of said shaft 23. Mounted on and insulated from said shaft is a commutator 44 having'one part cut away for half the distance around its circumference in which place is set an insulating piece 45, with Ybrushes 45, 46 bearing on the commutator so that for one half of a revolution of said shaft 28 said commutator 44 makes a circuit between said

brushes

46, 46 and for the other half it breaks the circuit. Said

brushes

45, 46 connect to the

leads

41, 41 one of which. includesY a source of electric energy 48 for a purpose hereinafter described.

Over said table l5 is mounted a cutting head 5i! inv operative relation to a plate 5I on said table i5,in vsimilar relation to that of said scanning head 30 with respect to said picture 3|. Said cutting headV 5i?!V rides on a bar 52 mounted to said sidesy I3, I3, across said bed I0 and re- 'the front plate 88.

hold between them the oval shaped coil 35 which` extends horizontally edgewise through said slotsV ceives its motion from a belt 53 mounted on idler pulley 54 and driving pullet7 55, which latter connects through a set of interchangeable reduction gears (not shown) in gear box 55, through a connecting shaft 51 and pinion 53 to said bevel gear 3B. Through these driving means, said cutting head 53 will move in synchronism with said scanning head 30 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 55, or of gear box 39, or of gears 38 or any or all of them.

Said cutting head 53 (see Figures 5, 6 and 7) comprises a supporting rod 60, one end'of which rides in locking engagement in the slot 5i in said bar 52. From the other end of said rod il there depends a bar 62 having a vertical slot 63 therein in which latter rides a slide rod whose position in said slot 63 is fixed and vertically adjustable by means of the screw 65 which is threaded into said slide rod 64 at its lower end and has its upper end extending through an opening in said rod SQ where it has a knurled fixed head 63 bearing against the upper surface and a xed washer 61 bearing against the lower surface of said rod 60.

Said slide rod 64 intermediate its ends carries a yoke' which extends transversely in the direction away from said bar 52 and which carries within itself an electromagnet 53 having a polepiece 15 extending in the direction toward said bar 52. Said electromagnet 69 is energizedlby said source 48 through said leads 41, 41 a manner and for the purpose hereinafter described. An armature bar 12, hinged to the lower end of said slide rod 34 through an oifset 13, extends vertically upwards and carries at its upper end a transverse bar 14 which extends through an opening 15 in said slide rod 54 and carries an armature 13 in operative relation to said pole piece 1li.V

Extending oppositely from said bar 'i4 and fixed to said armature bar 'l2 is a Vsupport bar 11 which supports beneath it a permanent magnet yoke 13, which latter at its outer end carries an electromagnet 'I9 and at its inner ends carries the pole-pieces 80, Si having therein, respectively, the oppositely facing slots 82, 33. Said eld coil 19 is energized by direct current during operation of the mechanism, Clamped one on each side of said pole pieces 83 and Bl, by means of the bolts 85 and 86, are the back plate B1 and Said bolts 85 and 83 also 82, 83. Extending centrally lengthwise the longitudinal opening of said' coil 95 is the flat armature 91 which carries, one at each end, the flexible loops 98, 93, each of which'is mounted on one of said bolts 85, B3 which loops 33, 98 allow a small rotative movement of said armature 91 about an axis which is the median of said coil 95. To be actuated by such rotative movement of said armature 91 is a vertical tool holder Ill!) which connects at its upper end through a flexible link IGI to said armature 91, said link lill being ilexible in a direction at right angles to said coil 35. At its lower end said tool holder Ill terminates in a chuck H32 which carries a cutting tool H33.

Clamped between a shoulder E34 .and an adjustable nut. I35 on said tool holder Ii is a flexible annular diaphragm IBG which serves to hold the lower end ofsaid tool holder lilil and to Vsteady it during movement. Said diaphragm |06 is attached by the four screw bolts |01, |01,.nea.r its edges, to a bar |08 xed to the bottom of said yoke 18 under the pole piece end and extending outwardly therefrom with an opening |09 therein through which said tool holder |00 passes.

To one side from said tool holder |00, said bar |08 carries a vertical guide I5 through which extends a vertical slide bar ||6 which has a longitudinal passageway ||1 extending therethrough and carries a horizontal bar ||8 projecting therefrom under said diaphragm |06 with an opening ||9 therein into or through which said tool holder |00 passes. A longitudinal passageway |20 within said bar ||8 connects at its inner end with said passageway ||1 and at its other end terminates in a U-.shaped opening |2| through the lower face of said bar ||8 about said opening H9. In the bottom face of said bar ||8 adjacent said opening |2| is another opening |22 which connects with said passageway |20 and which carries therein the supporting roller |23 which is adapted to ride on and to carry the cutting head 50 over a plate 5| to be cut by said tool |03. Means (not shown) for drawing .a suction through said passageways ||1 and |20 will draw chips cut from the plate and any dirt from under and through said openings |2| and |22. A brush |24 fixed in said opening |22 and bearing on said roller |23 will wipe off any chips or dirt adhering to the latter and release them to be carried away by such suction. A gear rack |25 fixed to said slide bar ||6 engages a pinion |26 in said guideway ||5 which latter carries a spindle |21 which passes through a friction, bushing |28 in a wall of guideway ||5 and terminates in a knurled head |29. By turning said knurled head |29 to move said pinion |26 on said rack |25, said cutting head 50 can be raised or lowered to suit the length of said tool |03 and to suit the length of the cutting stroke thereof.

In Figures 8 and 9 said cutting tool |03 is illustrated in detail in which the shank carries at one end the cutting point |36 which has two cutting edges |31, |31 which taper to a point from said shank |35 and for making a plate of a given screen the angle A defined by said edges |31, |31 is predetermined the value of said angle A being smaller for ne screens than for larger ones. The bisecting line of said angle A is at right angles to the plate being cut. The face |38 of said cutting point |36 is cut upwardlyl 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 |31 to give them clearance and in the form here illustrated denestwo faces |39, |39. To give bottom clearance, said cutting point |36 is cut upwardly and back from the tip at an angle C from the horizontal whereby'a diamond shaped face |40 is defined in the embodiment of the tool illustrated in Figures 8 and 9.

-In one embodiment of the present invention, said leads |58 and |62 connect and carry power to an electric glow lamp |63 (see Figure 3) but any kind of electric lamp can be used in which the light therefrom will vary appreciably and without lag with the amount of current supplied thereto. In operative relation with said glow lamp |63 is a photo-electric cell |64 with a cylindrical condensing lens |65 between them to focus light from said glow lamp |63 onto the cathode of said photo-electric cell |64, a slit |66 being used to define a narrow beam. Between said glow lamp |63 and said photo-electric cell |64 is the movable light interrupting disk |61 (see Figures 1 and 18) (a movable ribbon |68 in Figure 3') which in the embodiment illustrated in Figure 1 is driven by said cutting table |5 through a stud |10, xed to the latter and connected to a chain |1| (which can be a rack and pinion or other equivalent) through a sprocket |12, a. gear train |13 and the shaft |14 on which latter said disk |61 is mounted. Said disk |61 (also said ribbon |68) is opaque, with openings or transparent sections |15, |15 spaced at regular intervals therein along the portion which passes under the light, the width of the openings or transparent parts being preferably equal to the width of the opaque sections |16, |16 between them.

From said photo-electric cell |64 leads |80 and |8| connect with the cutting amplifier |32 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 photo-electric 'cell |64 to sufficient strength to operate said cutting head 50. Leads |83 and |84 connect said cutting amplifier to said coil 95 (see Figures 5 and 6). When a pushpull type amplier is used the lead |85 connects from the source of high potential of the amplier to the midpoint of said coil 95.

In the operation of the above described embodiment of my invention for making a printing plate from a picture or other delineanient, a picture 3| is placed on said table I4 laterally within the movement range of said scanning head 30. The said picture 3| 'can be aligned with the direction of movement of said table |4 or transverse thereto, but preferably for black and white printingV 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 17 which show sections of the printing plate) whereby adjacent dots of a given shade, black or white, areadjacent only at the corners thereof thereby avoiding continuous bands of black or white of more or less continuom width in the longitudinal direction which produces Yan optical illusion which detracts from the desired effect in the picture. The manner of cutting is more fully explained hereinafter.

When a positive plate 5| is to be made from a positive picture 3|, or a negative printing plato 5| is to be made from a negative picture 3|, then said scanning head 30 and said cutting head 50 are moved in opposite directions across saidk bed |0; and, if a negative printing plate 5! is to be made from a positive picture 3|, or a positive plate 5| is to be made from a negative picture 3|, then said scanning head-3|1 and said cutting head 50 are moved in the same directionV across said bed I0.

Said picture 3| and, plate 5| being properly placed and xed on their respective tables I4 and i5 by suitable meansnot shown, said scanning head 30 is brought to lower end of said bar 32 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 3| to be to the right beyond the line of travel of said scanning head 30. 1f said picture 3| is apositive and a negative plate is to be cut then said cutting head 50 is moved to the upper end of said bar 52 in Figure 1 and said table l5 is far enough to the right to bring the left hand corner of said plate 5| to. the right of the line of travel of said cutting head 50.

The various electric circuits and sources of light are now energized and said motor 21 is set in motion, whereupon said tables |4 and I5 begin their synchronous forward and backward movements and said scanning head 30 and cutting head 50 commence their slow movement across the picture 3| and plate 5|, respectively. During forward' movement of said table i4 said commutator 44 is inthe open circuit part of its rotation and said electro-magnet 69 is de-energized leaving said cutting head 50 down in the plate cutting position, and during the backward movement of table |4 the circuit between said source of electric energy 478 and said electro-magnet 60 is Vclosed through said commutator 44 and said cutting head 50 is lifted out of the plate cutting position. This movement of said cutting head 50, by Said electromagnet 63, into and out of plate cutting position is through movement of said armature bar i2 on its hinged connection at the lower end of said slide rod 54.

Light from said source of light 33 is reflected from a point on' said picture 3i to said photoelectric cell 34, the amount of light reaching the latter being proportional to the degree of light or shade at the point of reliection. Likewise the value of the current which flows through said photo-electric cell 34 and the circuit connected thereto, including said screening amplifier |50 and glow lamp |63 is proportional to the amount of light reaching said photo-electric cell Said glow lamp |03 is now energized and gives Yoff light which varies in strength as therdegree of the light and shade of the points passing under said scanning head 30 varies, and light therefrom illuminates and affects said photo-electric cell |64. rotating and entirely cutting off successive portions of the light passing to said photo-electric cell |64 whereby the current flowing through said photo-electricY cell |04, said coil 05 of cutting head 50 and the circuit therebetween varies in alternate succession to a minimum in accordance to the normal dark conductivity of said photoelectric Acell |04 when the light is cut off therefrom and also varies in accordance with the degree of lights and shades on said picture 3l.'

The graph in Figure 11 indicates the values of this current when the scanning head 30 is passing successively over light, grey and dark section of the picture 3|. Figures 12, 14 and 16, respectively, show, enlarged cross-sections of parts of said plate 5| having cut therein,- respectively, the depressions 20|', 202 and 203 by said tool |03, the depths of these said depressions beingproportional to and the areas of the horizontal or print- Said light interrupting disk |51' is nowv ing faces of the

elevations

204, 205 and 205 between said depressions 20|, 202 and 203, respectively, being inversely proportional to the values of those parts of the current curve in Figure 11 marked,.respectively, light, grey and dark. Face views V(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

204, 205 and 206 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 5| having

elevations

201i, 205 and 206 thereon of various areas of horizontal or printing surface. The slanting arrows indicate the direction oi movement of the cutting tool |03 in going over the plate 5| during the cutting operation. Where the depressions in the plate 5l run in together as Figures 12, 13 and 14, 15 the elevations (204, 205) are in the forms of frustums of four-sided prisms, with the top faces of the frustums forming the ink receiving areas. The depressions 20|, 202, and 203 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 out away was equal to the printing area (made up of the faces of elevations 205, 205) which is left. Here the depressions 202, 202v are in the form of inverted four-sided pyramids. In Figures 12 and 13 the depressions 20|, 20| 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.V

Here again the

depressions

203, 203 Yare in the form of inverted four-sided pyramids.'V In some cases the lateral faces of said depressions 23 l, 202 and 203 are not true planes but can be slightly concave, due to the shape of the energy curve of the current supplied to Said coil 05 and the resultant movement of said cutting tool |03 with respect to said plate 5| as the two are moved, the former up and down and the latter hori- Zont'ally. In the claims however the depressions and elevations are described as being pyramidal or substantially pyramidal. Y

In Figure 1() is illustrated an alternative einbodiment of the scanning system above described and in which an electric lamp 2 l0 (or other constant source of light) is positioned in operative relation to throw a beam of Vlight on said photoelectric cell |54, an optical system 2|| being used to concentrate said beam of light. A light-valve 2|2 connects to said leads |58 and |02 and operates in a manner well known in response to variations in current passing through said leads |58, 52 to regulate the distance of the opening of the light valve whereby the light impressed on said photo-electric cell |54 is proportional to the degree of light reflected from said picture 3|, as successive parts thereof pass under said scanning head 30, the light interrupting ribbon |58 or disk |61 being used as above described to interrupt thelightpassing to said photo-electric cell 164.

The method and apparatus of the present iny head. In such case a number of cutting heads could be set up in operated relation to one scanning 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 plate cut by the apparatus of the present invention and certain features in the method of cutting employed in the use of this apparatus are described and claimed in my U. S. Patent Number 2,032,541 issued March 3, 1936, application for which was filed Sept. 5, 1934, Ser. No. 742,715 and was copending herewith. Other features of the method used in the employment of the apparatus of the present invention are claimed in my copending application Serial Number 647,884, led December 19, 1932.

Having thus described my inventori what I claim and wish to protect by Letters Patent is- 1. In a machine for reproducing a picture on the surface of a printing plate, the combination of means for directing a beam of light to travel over the picture and a photo-electric cell for receiving the reflected beam from the picture, and

, an electro-mechanical plate-cutting device, a second photo-electric cell, electrically connected to said electro-mechanical device; a, source of light in operative relation to said second photo-electric cell; and means controlled by first said photoelectric cell adapted to control the amount of light passed to said second photo-electric cell n accordance with the amount of current passing through first said photo-electric cell; and means for regularly interrupting the light to said second photo-electric cell.

2. In a system for transforming light energy into mechanical energy, in combination, a light source, a photo-electric cell in operative relation to said light source, an electric poweramplifier having its input side connected in operative relation to said photo-electric cell, a second light source connected in operative relation with the output side of said electric power-amplifier, a second photo-electric cell in operative relation to said second light source, a second electric power-amplifier having its input side connected in operative relation to said second photo-electric cell, an electro-mechanical cutting tool connected in energized relation to the output side of said second electric power-amplifier, and light interrupting means between said second light source and the photo-electric cell which is in operative relation thereto.

3. In a machine for reproducing a picture on the surface of a printing plate, in combination, means for directing a beam of light to travel over the picture, a source of electric light, means for transforming the variations in the light reflected from the picture into variations in an electric current passing through said source of electric light, a plate cutting tool, a circuit for passing an energizing current to said plate cutting tool, a photo-electric cell in said circuit and in operative relation to receive light from said source of electric light, and a light interrupter between said source of electric light and said photo-electric cell.

4. In a machine for reproducing a picture on the surface of a printing plate, in combination, means for directing a beam of light to travel over the picture, a source of electric light, means for transforming the variations in the light reflected 'from the picture into variations in a continuous electric current passing through said source of electric light, a plate cutting tool, a circuit for passing an energizing current to said plate cutting tool, a photo-electric cell in said circuit and in operative relation to receive light from said source of electric light, and a light interrupter between said source of electric light and said photo-electric cell.

5. A machine for reproducing a picture on a surface of a plate, comprising a transmitter including an electric lamp and means for scanning the picture and transforming the variations of shading into variations of current ow to said electric lamp, a translator including a plate cutting tool and a photo-electric cell which is in light receiving relation with said electric lamp, and means between said electric lamp and said photo-electric cell for periodically interrupting the light path therebetween.

6. A machine for reproducing a picture on a surface of a plate, comprising a transmitter including an electric lamp and means for scanning the picture and transforming the variations of shading into variations of current iiow to said electric lamp, a. translator including a plate cutting tool and a photo-electric cell which is in light receiving relation with said electric lamp, and means for periodically stopping ow of light from said electric lamp to said photo-electric cell.

GEORGE E. LOSIER.