US2713294A - Photocomposing machine - Google Patents

Description

July 19, 1955 J. D. PADGETT 2,713,294

PHOTOCOMPOSING MACHINE Filed Feb. 15, 1955 5 Sheets-Sheet l Jay D. Para gaff INVENTOR ATTORNEY y 1955 J. D. PADGETT 2,713,294

PHOTOCOMPOSING MACHINE Filed Feb. 15, 1955 5 Sheets-Sheet 2 day Q Pa /gaff INVENTOR July 19, 1955 J. D. PADGETT PHOTOCOMPOSING MACHINE 5 Sheets-Sheet 3 Filed Feb. 15, 1955 INVENTOR M M P a 9 4 July 19, 1955 J. D. PADGETT PHOTOCOMPOSING MACHINE 5 Sheets-Sheet 4 Filed Feb. 15, 1955 ATTORNEY numw July 19, 1955 J. D. PADGETT 2,713,294

PHOTOCOMPOSING MACHINE Filed Feb. 15, 1955 5 Sheets-Sheet 5 Jay 0. Padgeff INVENTOR United States Patent Qfhce This invention relates to photographic printing machines and more particularly to an apparatus for and method of transferring subject matter of a negative to a sensitized plate.

This application is a continuation-impart of my application Serial Number 409,499, filed February 10, 1954 for Methods and Means for Maiti g Photographic Exposures.

Accuracy in the positioning and aligning of the images to be transferred from a negative to the sensitized plate in step and repeat printing has been accomplished in several differ nt ways through the medium chiefly of frames. lJc-vertheless, the trade deer precision in obtaining proper register 1 less t t e consuming labor which is ones because of the absence of adequate retention of. es once proper registry is attaiied. Prior devices for obtaining alignment of the plates and for retairing alignment thereof include various types of tapes, clamps and the like attached to the printin frame and which detract from the flexibility of the apparatus while seeking to reduce time and skill the preparation of the Work for printing.

it is the primary object of the present invention to provide an improved apparatus for and method of insuring greater accuracy in positioning the negative or color transparencies 1-. relation to the plate and for holding the negative and plate in any desired position on the deck or bed of the pr ing frame by positioning elements arranged in predetermined relationship with each other and with said negative and plate and which positioning elements require no fixed means of attachment to said printing frame.

Another object of the invention is to provide a photographic printing machine employing a vacuum frame which is composed of a cover frame and a magnet bed of corresponding dimensions, the cover frame being hinged along its rear edge to the rear edge of the magnet bed, both the cover frame and magnet bed being pivoted for rotation about a horizontal axis extending through the top rnidsection of a cabinet.

Anotl'xer object of the invention is to provide, in a photographic printing machine, a magnet bed in which permanent bar magnets of substantially U-shape in transverse section are fioatingly assembled in end to end relationship in parallel rows extending preferably diagonally from side to side of the frame embracing the bed which underlies the air impervious blanket common to most t pes of vacuum frames. The north poles of the magnets, as are the south poles, are disposed in juxtaposition for repulsion and this feature, combined with the fact that the area covered by the magnets creates a magnetic field substantially equal in area to the blanket which is devoid of inactive spots.

Another object of the invention is to provide, by virtue of the magnetic field, a medium by which negatives, color transparencies, stencils or the like may be held on non-ferrous printing plates by ferrous rules, chase or bars with no 'i' another object of the invention is to provide a -'el coin. ldlancing means for the transparent cover of he vacuum frame and a safety latch which interlocks the cover and magnet bed in vertical position of these a nts to prevent tilting of the cover frame independently of the magnet bed.

till another object of the invention is to provide stop means for preventing unlatched condition of the finct at all times during periods of loading or the cover frame is in raised position and to provide ase or" the stop means in lowered position of the cover rarne.

Still another object of the invention is to provide a masking means consisting of spring biased roller curtains of black, light-proof material, each capable of being independently drawn into overlapping relation to another to overch the operative area of the vacuum frame and securable in positions to define the particular area occupied the ative on the printing plate or film, as the Q56 may be. and thus prevent exposure of the plate *eyond that necessary to reproduce the image in the step and repeat process.

With the foregoing and other objects in view, the invention has reference to certain salient features of construction and arrangement of parts which will become manifest a 'ne description proceeds and which are illustrated in the accompanying drawings, wherein:

Figure l is a front perspective view of a photographic 'ng machine embodying the invention in which the cover frame is shown in raised position.

Figure 2 is a View in vertical section, dotted lines the printing position.

Figure 3 is a rear view 5 the machine in which the printing frame is shown in vertical position.

Figure 4 is a fragmentary perspective view showing one of the clamps for securing the masking curtains in adjusted positions.

Figure 5 is a top plan view of the machine with portions of the top cover and blanket broken away to show the magnet bed beneath.

Figure 6 is a fragmentary perspective view showing the air outlet for evacuating the vacuum printing frame.

Figure 7 is a fragmentary sectional view of the printing frame showing the floating action of the magnets as influenced upwardly by the rule elements.

Figure 8 is a fragmentary perspective view of the magnet bed.

Figure 9 is a vertical sectional view taken on line 9-9 of Figure 5.

Figure 10 is a vertical sectional view taken on line 1tl-ltl of Figure 5.

Figure 11 is a fragmentary net bed.

Figure 12 is a detail view of the safety latch for preventing accidental release of the printing frame from its latched position in the cabinet, and

Figure i3 is 2 fr :5! p front corner of the machine showi of one of the magnet bed latches.

Continuing with a more detailed description of the drawing, reference numeral 19 denotes generally the cabinet of the printing machine which is constructed of This showing in frame in vertical or exposing top plan view of the magview of no 21g an enlarged detail is to enable the machine to be moved in sections through doors of standard width.

The lower section 12 has a bottom portion 13 set inwardly from the front of the cabinet to provide toe space for the operator, and vertically adjustable supporting legs 14 enable the cabinet to be leveled on uneven floors.

The upper section 11 of the cabinet has a flange 15 (Fig. 2) about its lower edge which abuts a like flange 16 about the upper edge of the lower section 12 and bolts 17 secure these flanges together (Figure 2). The top of the upper section 11 is slightly upwardly inclined rearwardly toward the rear of the cabinet to afford a more facile Working plane.

Referring to Figure 2, it will be observed that the cabinet 19 has a vertical, transversely extending partition 13 which separates the front compartment 19 from the rear compartment This partion is in transv sely panels (Figure 3) for ready removal and access to the compartment 19 which contains the controlling elements of the printing machine and which will be presently described and explained.

The upper edges of the front and sides of the upper section 11 of the cabinet are curved inwardly at 21 (Fig. l) and extending from side to side of the section 11 is a plate 22 (Figure 2) inclined to the same plane as the top of the cabinet and terminating at the top of the panels forming the horizontal partition 1%. This plate 22 has side flanges 23 (Fig. 2) which extend upwardly and meet with the inturned edges 21 of the upper cabinet section 11. The plate 22 is supported on angles 24 (Fig. 2) aflixed to each side wall of the cabinet. This plate 22 serves no other purpose than to close the top of the compartment 19 of the cabinet when the printing or vacuum frame, broadly designated by reference numeral 25, (Fig. 5) is tilted to the vertical position, as shown in dotted lines in Figure 2 The printing frame 25 (Fig. 5) is composed of the magnet bed generally indicated by reference numeral 26 and a cover frame generally indicated by reference numeral 27 (Fig. 2) The magnet bed is composed of a rectangular frame 28 formed of flat, inverted channel members secured to a flat base 29 by screws 2% (Figs. 9 and 10). Within the confines of the channel members or sides of the frame 28 is arranged on the bed or base 29 a plurality of diagonal rows of bar magnets 39 (Figs. 7 and ll) of substantially U-shape in transverse section. Each row of magnets St is separated from another by means of spacer bars 1.1) each of which is continuous from side to side of the magnet frame 28 and is held to the base plate or bed 29 by means of screws 32 (Fig. 7). The top surfaces of the spacer bars 31 are flush with each other and with the frame 23 while the common upper plane of the magnets an is slightly below that of the spacer bars 3% and the frame 23 (Fig. '7). This permits the magnet 36 to float or move upwardly. Upward movement of the magnets, as caused by influence of ferrous elements thcreabove, is limited by retainer bars 33 (Fig. 7) which lie between the upstanding flanges of the magnets 38! and extend beyond the ends of each row of magnets and are secured by screws 34 to the tops of ferrules 35 (Fig. 8), the screws extending through the ferrules and threaded into holes in the bed plate 29, which is likewise true of the screws 32 which hold down the spacer bars 31.

The magnet bed 2? is suspended on the pivots 46 (Figs. 2 and 5) at a point slightly forwardly of the center of gravity so that its normal tendency is to move in the direction of the vertical plane.

The magnets are capable of limited lateral and longitudinal displacement, restricted by the relative spacing of the spacer bars 31 between which the magnets are arranged. The magnets are disposed with their north poles in juxtaposition so that one will repulse another and thus insure a complete and unbroken magnetic field throughout the area of the bed plate 28 covered by the magnets.

The base plate 29 extends beyond the sides and ends of the magnet frame 25, as shown in Figures 9 and 10 and to each extended side of the plate 29 is secured, by means of screws 36, a flat rail 37. A similar but narrower rail 33 is secured by means of a screw 39 (Fig. 9) to the extended rear edge of the base plate 29. These rails 37 and 33 form a rectangular support for the perimeter of a blanket 44) (Fig. 9) whose sealing flange 41 is longitudinally coextensive with each side rail 37 and the end rail 38. Further reference to the blank t 46 will be made presently.

Mounted on the inclined plate 22 at each rear corner (Figure 2) is a magnet bed hinge bracket 42. Bolts 43 secure this bracket to the plate 22. The upper end 44 of this bracket extends through a slot 45 (Figure 5) in a block 45:; seated in a recess in each of the two side rails 37 on opposite sides of the magnet bed 29. A pivot pin extends through matching holes in the upper end of bracket and the bearing block 4511, thereby supporting the printing frame 25 for rotation about an axis through the pivot pins 46 from a plane parallel with the inclined top of the cabinet l5 into a vertical plane suggested by dotted lines in Figure 2.

The air tight cover frame 27 is composed of side flanges 47 of right angular cross-section (Figure 10) and front and rear flanges 48 (Figure 9) of like cross-sectional shape. A glazing frame 49 (Figures 9 and 10) is spaced inwardly from the side and front and rear flanges 4'7 and 43, respectively, and from the top of the frame 27. Such spacing provides an elongated recess or chamber 50 coextensive With each side of the cover frame and a like recess or chamber 53 along the front and rear edges of the frame. These recesses are adapted to contain the rollers on which are wound curtains of light proof material which will be explained later.

Mounted on the glazing frame 49 are the edges of a glass panel 52 which are made air tight with the frame 49 by a suitable sealing medium 53 (Figures 9 and 10). The glass panel 52, when the cover frame is lowered into operative position, is in contiguous engagement with the sealing flange 4-1 of the rubber blanket at The cover frame 27 is joined to the magnet base plate 29 by means of plate hinges 54 (Figure 10), one flange of each hinge being afiixed by screws to the underside of the rear member of the glazing frame 49 while the companion flanges of the hinges 54- are similarly secured to a rail 55 (Figure 9), secured to the underside of the magnet base plate 29 along its rear edge. It is evident therefore that the cover frame 27 may swing upwardly from the position shown in solid lines in Figure 2 to the position shown in Figure l, in which position the cover frame is counter-balanced by means of a spring assembly shown in Figure 9.

The spring assembly for counterbalancing the cover frame 27 consists of a heavy coil spring 56 contained in a tubular housing 57. A pair of identically shaped com pression rods 53 and 59 are employed. The compression rod 58 is formed into an elongate U-shape having the ends bent into return hooks Gil which are slidable in diametrically opposed, longitudinal slots originating at one end of the tubular housing 57 as the spring is brought under compression by lowering the cover frame. The bight end 61 of the compression rod 58 is attached, by means of a bolt 62 to the downwardly and rearwardly extending leg 63 of a bracket 64. The bracket 64 is secured by bolts 65' and as to the under side of the glaz ing frame 4%, as shown in Figures 9 and 10.

The companion compression rod 59 has its legs extending also through the coil spring 56 in a plane at right angles to that of the compression rod 53 and the ends of the compression rod 5@ are bent into books 67 which are slidable in diametrically opposed slots 68 in the opposite end of the tubular housing 57 and engage the end of the spring 56 opposite the hooks fit) of the companion compression rod 53. The bight portion of the U-shaped 5 compression rod 59 is attached to a pin 69 (Figure 2) carried by a bracket 7% secured on each side of the magnet base 29 adjacent the pivotal pins 4-6 thereof.

The cover frame is counterbalanced by compression of the spring by the oppositely disposed compression rods 58 and 59 and it remains in any angular position to which it is moved. Maximum compression of the spring exists in lowered position of the cover frame and minimum compression exists when the frame is disposed in its highest position.

In preparing the machine for printing, 21 ca elated rule bar 71, negative holder 2 and a scale bar '73 (Figure 5) are employed. These elements are made of steel or other ferrous metal and are preferably highly flexible. The initial step of laying out the work may be accomplished on a light table or other flat surface and transferred to the blanket in of the machine for al on the sensitized printing plate 74. For this reason, scale members 'Fl, 72 and 7'3 are made independent of the machine and, being ferrous, they are strongly attracted by the magnetic field created by the magnet bed over which the work is placed for printin The first step is to position the negative 75 accurately with respect to the scale bar 73 or its equivalent, after which the negative holder 2, which is simply a thin fiat rectangular strip of ferrous metal, is located with respect to the scale bar 73 by means of the single line 76 midway of its ends and which is brought into proper register with the calibrations on the scale bar '73. The negative is secured to the negative holder 72 by means of a strip 77 of adhesive material which is applied to the undersurface of the negative and negative holder.

When the printing plate 74*? is positioned on the bla t if the lateral leg 78 of the scale bar '73 is placed against the calibrated edge of the rule bar 71 which extends across the printing plate 7 the calibrated members 71 and 73 forming a right angle in cases where the step and repeat process involves work, such as illustrated, where the scale members can be positioned in parallelism with the sides and ends of the printing frame.

it is, of course, desirable in carrying out the process to accurately locate the negative 75 in the lower left hand corner of the printing plate 74 for the first exposure and proceed progressively across the plate with successive exposures, after which the exposures are made successively upward, thence downwardly where the next adjacent vertical rows of exposures are made until the entire plate 74 has been exposed, the scale members and negative holder being drawn firmly against the blanket 4% by the magnet bee and will not become displaced from their fixed positions except by manually lifting them out of the field of influence created by the magnet bed.

When the Work is assembled on the blanket in the manner described or in accordance with any conventional practice, the cover frame 27 is closed. The switch '79 (Figure 1) which starts the motor Si (Figure 2), is actuated, the motor operating the pump 81 to evacuate the vacuum tank 82. A line 83 (Fig. 6) eff ct communication between the ta 32 (Fig. 2) and the s ace formed between the cover frame 25 and blanket by means of an air outlet 84 (Figures 2 and 6). A vacuum control switch 35 (Figure l) is actuated to open the line 33 to evacuate the air in the space between the cover frame and blanket, whereupon the blanket is forced u wardly by atmospheric pressure and absence of air it said space and bears firmly a let the printing plate 74, the negative and the work holding elements, as exemplified in Figure 7.

As the blanket 49 moves upwardly, the particular magnets 3b which underlie the ferrous elements on the blanket, are drawn upwardly by their attraction to these elements, there being provided a space between the bases of the magnets and their retaining bars 31 for upward displace ment of the magnets a distance substantially equal to the upward displacement of the blanket 4 The magnets other than those influenced upwardly by the ferrous elements remain, of course, at rest.

During loading operations, the magnet base frame is held down by means of a latch 87 (Figures 2 and 13) which extends upwardly through a slot 88 in the plate 22 underlying the magnet base. The latch 37 has a hook 39 which engages a large pin 95 affixed to and extending laterally outward from a lug or keeper 91, affixed by screws 92 to the magnet base frame member 37.

By referring to Figure 2, it will be seen that the lower end of the latch 87 is apertured to receive an end of a longitudinal shaft 93 'ch extends from side to side of the cabinet it) immediately behind the instrument panel 94 which is recessed in the front wall of the cabinet. To this shaft 93 is rotatably connected the rear end 95 of a pull rod. 5 6 which extends laterally through an opening in the panel and carries a pull knob 97 (Figure l). pulling this rod, the shaft 93 is rotated to tilt the la. rearwardly and disengage itself from the pin 90 by which it is connected to the magnet bed frame. The pull rod 96 is biased inwardly by a coil spring as (Figure 2), connected at one end to the lower end of the latch 87' and. at its opposite end to upper edge of the plate 22. inc cover frame 25 has a latch 98 (Figures 1 and 2) swingingly suspended by a pivot pin from each of its front corners. When the magnet base and cover frame are in lowered position, the cover frame is released from locked relationship with the magnet base since the small, laterally extending pin liltl, carried by the latch 8'7, is engaged by the cam surface llll (Figure 2) on the swinging latch )3, causing the latter to move forwardly, dis engaging itself from the large pin 9% and freeing the cover frame for independent movement in relation to the magnet base.

When the work has been composed on the blanket as preparatory to exposing to light, the pull 96 is drawn outwardly to disengage latch 87 to free the magnet base frame for upward movement, whereupon the cover frame is grasped by the lifting rail along its front edge and is raised. As the cover fran s is moved upwardly, the latch 93 swings by gravity into locking position with the large pin i l"! on the magnet base thereby locking the cover frame and magnet base together. This is important since the cover frame, when the assembly is in vertical position for exposure, would tilt backwardly away from the magnet base if the vacuum holding the cover frame and magnet base together should fail.

'When the assembly is disposed in the position shown in Figures 1 and 2, the negative and plate or film are exposed to a brig.t light for a duration predetermined by the setting of a timer 163, after which the operation is repeated until the desired area of the printing plate has been exposed.

Adjacent the timer W3 on the instrument panel 94 is a vacuum gauge 1&4 which is in communication with the vacuum tank 82 by means of a tube 1&5 (Figure 2).

To avoid any possi lity that the magnet base or frame 29 be released from its latched position in relation to the cabinet 16 while the cover frame 27 is in raised position, a. latch stop bar 137 (Fig. 12) is pivotally mounted on the under side of one edge of the magnet base frame rail 37 as seen in Figure 13, immediately behind the latch 87 to prevent its rearward movement should the pull rod 3 6 be accidentally actuated.

The latch stop bar 37 is oscillatably mounted on a pivot pin 333 which extends through matching holes in the parallel legs :39 of an inverted U-shaped bracket 1% (Fig. 13), secured by screws s ll to the under side of the magnet frame .il 3?. The forward end of the stop bar 137 is normally biased downwardly by a coil spring 14-2 interposed between said forward end and the under side of the magnet frame rail. Extending laterally outward from the rear end of the stop bar 137' is a pin 14 3 which is engaged by the lower edge of the side flange of the cover frame 27, as the latter is lowered, thus to tilt the f8o7rward end of the stop bar upwardly to clear the latch It is evident from the foregoing that when the cover frame 27 is in raised position, the forward end of the stop bar 137 will be compelled by the spring 142 to lie in the path of the latch 87, preventing its rearward displacement as effected by outward movement of the pull rod 96. Thus, the magnet bed cannot be freed for rotation on its pivots until the cover frame is lowered, which action brings the lower edge of the side flange of the cover frame into engagement with the lateral pin 143, rocking the stop bar 137 on its pivot 138 and raising its forward end free of the latch 87. Only then can the latch 87 be actuated. There is never a need that the magnet base be raised without its first having been latched to the cover frame so that I both may move together into vertical position for burning or exposure. Earlier in the description the provision for latching the two frames together was explained.

I n order that the exposed area of the printing plate 74 may be restricted only to the area thereof covered by the negative, a masking arrangement is provided which enables an operator to expose the entire working area of the blanket or restrict the exposure area to any size and at any position desired on the printing plate.

The masking arrangement is comprised of a roller 166 journaled at its ends in the ends of each of the compartments or recesses 51 at the front and rear of the cover frame 27. In like manner, rollers 107 are arranged in each of the elongate recesses at each side of the cover frame. Wound on each of the rollers 1136, which are constructed in the manner of a window shade roller, is a curtain 108 of light proof material.

Extending longitudinally across the cover frame 27 is a curtain bar 109 (Figure 5), to which is secured the end of the curtain 108 by means of a metal strip 110 which is parallel with the edge of the bar 109 nearest the roller 106. The curtain passes oif the roller 106 and over the vertical portion 111 of a guide rail 112 (Figure 9) of substantially T-shape in transverse section. The upper edge of the vertical portion 111 is curved and polished so that the curtain 108 will slide freely thereover as the curtain bar 109 is moved over the cover. The guide rail 112 is mounted on the front and rear portions of the glazing frame 49.

The curtain bar 109 is maintained in parallelism with the front and rear sides of'the frame by means of spools 113 (Figure 10) rotatable on pins 114 on the under side of mountings 115 which are formed by breaking the ends of the curtain bars 109 upwardly and outwardly as revealed in Figure 10. The annular grooves of the spools 113 receive the inner edges of a track 116 which is afiixed to the horizontal portion 117 of the flange 47 of the cover frame 27.

The curtains 108 which are drawn from the front and rear rollers 166 and their associated elements, as described, are identical, hence a description of the companion or front curtain is unnecessary. Each of the curtain bars 109 has a curtain pull or operating handle in the form of a vertical rail 118 which extends upwardly from the bar and is longitudinally coextensive therewith.

The side curtains 119 (Figure 10) are each drawn from a roller 107 and travel over a guide rail 120 of substantially L-shape in transverse section and whose vertical leg is secured to the glazing frame 49 along each end thereof. It is noted that the curtains of the rollers 107 travel under the curtains of the rollers 106, hence the guide rails 120 are on a lower plane than the guide rails 112.

To the end of each of the curtains 119 is secured by means of a strip 121a, a curtain bar 121 (Figures 1 and 10) which extends from front to rear of the cover frame 27, and at each end, the bar 121 is broken upwardly and again into parallelism with the plane of the bar to form a mounting 122 carrying a pair of spools 123, mounted on pins 124. The grooves of the spools receive tracks o, u 125, afiixed to and coextensive with the glazing frame 49 along its front and rear sides, as shown in Figure 9.

It is evident from the foregoing that each curtain can be operated independently of the other three, hence the confronting edges of the bars of the curtains can be moved relative to each other to define an exposure area of any dimensions and at any selected point throughout the entire operative area of the printing frame. It is necessary however that since the curtains are all normally biased toward their respective rollers, means must be provided for securing the curtains in their adjusted positions.

The securing means for the curtains is shown in detail in Figure 4 and consists of a block 126 which is of substantially L-shape in transverse section to form a longitudinal leg 127 shorter than the block 126 and which is slidably disposed on one side of a strip 128 which is afiixed to and coextensive with the curtain bar 121 of a curtain 119 and parallel with the securing strip 121a, as more clearly shown in Figure 3. The block 126 is slidably disposed on the top of the strip 128 and has a plate 129 secured by screws 130 to its side opposite the leg 127. The plate 129 is cut away at 131 and has a right angular lip 132 formed on its lower edge which extends under the strip 12%. The block 126 has a downwardly extending lip 133 formed on its end above the cut-away portion 131 of the side plate 129 and this lip, cut-away portion 131 and the block 126 combine to form a rectangular passage for a strip 134 which is secured to the curtain bar 169 opposite the strip 110 which secures the curtain to the bar.

From the foregoing, it is made apparent that the strip 128 of the curtain bar 121 is capable of longitudinal sliding movement between the block 126, its side leg 127 and the opposite side plate 129. In like manner, the strip 134 of the curtain bar 169 is capable of sliding transversely with respect to the strip 128. Therefore, the four curtains may be moved independently to define any sized opening at any point over the work surface.

To secure the blocks or curtain holders 126 in adjusted positions, a screw 135 is threaded through the block adjacent one end and bears against a wear plate 136 which, in turn, bears against the strip 134. Since the right angular lip 132 of the side plate 129 engages the under side of the strip 128 traversing the strip 134 and its curtain bar 1 13, tightening of the screw 135 will draw the members into clamped relationship. In this manner, the four curtains are held in adjusted positions, so that when the printing frame is disposed vertically for exposure to light, such exposure will be restricted to the opening defined by the positioning of the curtains.

Referring again to the magnet base of which it was mentioned earlier that the parallel rows of magnets 30 were disposed diagonally across the bed; it is pointed out that insofar as performance is concerned, the rows of magnets may just as well extend parallel with the sides or ends of the bed but for practical reasons the diagonal disposition of the rows of magnets is preferred. If the rows of magnets were parallel with the long axis of the work surface which is the plane in which most of the Work is laid out, the magnetic flux may not be as pronounced between the rows of magnets and it is possible that one of the scale members may be placed so that a major portion thereof will be between the paths of magnetic force and hence will not be as firmly held as they would be if the rows of magnets are arranged diagonally. Moreover, such diagonal arrangement of the rows of magnets is found to more evenly distribute the influence of the magnets through the steel composing elements.

It is further mentioned that while the masking arrangement is shown and described as overlying the glass in the cover frame, it is evident that without material change, the masking arrangement can be interposed between the glass and the blanket 4i Manifestly, the construction as shown and described is capable of some modification and such modification as may be construed to fall within the scope and meaning of the appended claims is also considered to be within the spirit and intent of the invention.

What is claimed is:

1. In a photocomposing machine, a cabinet, 21 rectangular printing frame mounted in said cabinet for rotation about an axis through its longitudinal midsection, said printing frame consisting of a magnet bed frame and a cover frame hinged to said magnet bed frame along its rear edge and having a transparent air tight top, a magnet bed in said magnet bed frame, a non-porous blanket overlying said magnet bed on which is adapted to be disposed a sensitized printing plate, a ferrous negative holder and scale members having registerable scale lines for orienting a negative in said holder in relation to said printing plate and maintaining the position of said negative and printing plate through ma netic attraction of said holder and scale members to said ma net bed, magnets in said magnet bed frame movable towards and from said cover frame by influence of said ferrous negative holder and scale members, and means for exhausting air from between said cover frame and magnet bed frame.

2. In a photocomposing machine, a printing frame comprising a tiltable magnet bed frame and a cover frame hinged to said magnet bed frame for independent movement and having a transparent top, marginal sealing means between said magnet bed frame and said cover frame, a plurality of rows of magnets in said magnet bed frame movable towards and from said cover frame and creating a magnetic field coextensive with the inner edges of said magnet bed frame, a non )OfOUS blanket disposed on said magnets defining a working area, a printing plate freely mounted on said blanket, elongate scale members of ferrous material attracted to said magnetic field throughout their lengths, one of said scale members being disposed at the margin of said plate and the second of said members bein slidable over said plate along the first member and extending transversely from said first member, a ferrous negative holder retained by said magnetic field and coordinating with said second member to eifect registration of a negative with said printing plate, means for securing said magnet bed frame and said cover frame in sealing relationship and means for exhausting air from between said frames preparatory to exposing said negative to light.

3. The structure of claim 2, and a curtain roller parallel with each side and end of said cover frame, each carrying a curtain adapted to be drawn independently of the other curtains over the transparent top of said cover frame, guide means for each of said curtains and means for securirn said curtains in drawn position to define an exposure area of any size and at any selected position throughout the working area of said blanket.

4. in a photocomposing machine, apparatus for obtaining accurate register of a negative on a printing plate comprising, in combination with a printing frame, a magnet bed defining a magnetic field coextensive with the working area of said printing frame, a rubber blanket overlying said magnetic field on which said printing plate is positioned, a light transmitting cover plate included in said printing frame; a first substantially thin, elongate scale bar of ferrous metal in parallelism with one edge of said plate, a second elongate scale bar slidable over said plate in register with scale lines on said first scale bar, a negative holder of ferrous material adapted to register with the scale lines of said second bar, said scale bars and negative holder being maintained in registering position by said magnetic field during and after orientation of said negative on said plate, said magnet bed frame including a plurality of magnets movable towards or from the cover plate by influence of said ferrous scale bars and negative holder; and means for evacuating said printing plate of air preparatory to exposing said negative and underlying negative to light.

5. In combination with the printing frame of a photocomposing machine, apparatus for accurately positioning a negative on a printing plate comprising a magnet bed producing a magnetic field coextensive with the Working area of said printing frame, said printing frame including a light transmitting cover; a blanket overlying said magnet bed on which said printing plate is positioned, said magnet bed frame including a plurality of magnets movable towards or from the cover; a first calibrated means of ferrous metal parallel with one edge of said plate, analogous calibrated means perpendicular with said first calibrated means adapted for sliding adjustment over said plate in relation to calibrations on said first calibrated means, a negative holder of ferrous material adapted to register with calibrations on said analogous calibrated means to orient said negative in relation to said plate, said calibrated means and negative holder maintaining predisposed positions of said negative and plate under the influence of said magnetic field While said negative and the underlying area of said plate are exposed to light.

6. The structure of claim 5, said magnet bed comprising a frame and parallel rows of magnets extending diagonally across said frame in end to end relationship.

7. The structure of claim 6 wherein the north and south poles of said magnets are reversed, one with respect to another to repulse each other both longitudinally and laterally to create an unbroken magnetic field.

S. In combination with the printing frame of a photocomposing machine, a magnet frame in said printing frame, said printing frame including a light transmitting cover; parallel rows of magnets occupying said magnet frame to create a magnetic field, a blanket covering said magnets means for registering a negative with light sensitive printing plate on said blanket comprising a substantially fiat ferrous holder for said negative, said magnet frame including a plurality of magnets movable towards or from the said cover; a pair of flat, elongate scale elements disposable in relation to each other and to said negative holder and influenced by said magnetic field into intimate contact with said blanket and portions of said printing plate and effective to orient said negative in relation to said printing plate and to maintain predisposed relationship of said negative and plate during exposure thereof to light.

9. The structure of claim 8, wherein said rows of magnets are arranged diagonally in relation to said frame.

10. The structure of claim 9 wherein the north and south poles of each magnet are opposed to corresponding poles of adjacent magnets for repulsion of the magnets with respect to each other to create an unbroken magnetic field.

References Qited in the file of this patent UNITED STATES PATENTS 1,813,689 Weisker July 7, 1931 2,129,768 Huebner Sept. 13, 1938 2,259,238 Bernhard Oct. 14, 1944 2,587,084 Anderson Feb. 26, 1952 FOREIGN PATENTS 22,112 Great Britain Oct. 10, 1902 540,700 Great Britain Oct. 27, 1941

Images