US2919635A - Printing exposure machine for photosensitive materials - Google Patents

Description

Jan. 5, 1960 s. w. LEVINE ETAL 2,919,635

PRINTING EXPOSURE MACHINE FOR PHOTOSENSITIVE MATERIALS Filed Sept. 17, 1956 2 Sheets-Sheet 1 s g 74 /0 VIIIIIII 5. W L EV/NE H. S/GL 52 BY g 7 Wm Wk ATTORNEY INVENTORS Jan. 5, 1960 s. w. LEVINE HAL 2,919,635

PRINTING EXPOSURE MACHINE FOR PHOTOSENSITIVE MATERIALS Filed Sept. 17, 1956 2 Sheets-Sheet 2 United States Patent PRINTING EXPOSURE MACHINE FOR PHOTOSENSITIVE MATERIALS Samuel W. Levine, Westbury, and Harold Sigler, Brooklyn, N.Y., assignors to Fairchild Camera and Instrument Corporation, a corporation of Delaware Application September 17, 1956, Serial No. 610,270

2 Claims. (Cl. 9573) This invention pertains to printing equipment of the photographic type; more specifically, it pertains to equipment in which a photosensitive material is held in close contact with a negative or other image bearing sheet, and subjected to rays of light passing through the latter to form a reproduction of the negative or master. The word negative is used here in an illustrative sense, because whether the original or master is a negative or a positive will depend both upon the nature of the photosensitive material and the use to which the reproduction is to be put. Various forms of such equipment have been proposed, especially for photographic printing; while the machine of the present invention is adaptable to printing upon con ventional photographic materials, it has features which especially adapt it for the exposure of the socalled photopolymer materials characterized by the ability to be locally hardened by the, action of actinic rays such as light or ultraviolet radiation. Such materials, of which the art affords many examples, can be exposed as indicatedv above to produce selective local hardening in accordance with the master image, and can be thereafter deiieloped as Washing out the unhardened portions to product a relief image suitable fer matting or even for direct surface printing by letter-press, offset or other familiar printing techniques.

Since materials, such as the photopolymers mentioned above, which are intended to yield a substantial relief image, will generally be thicker and often stiffer than simple photographic film or paper stock, the ability to maintain intimate contact of the original with the material isan especially desirable feature of the equipment. Also, certain types of the materials require a higher total exposure than is common with photo films or plates, which is' not necessarily a disadvantage since it gives relative immunity to amb ient light or .fog exposure. The apparatus of the present invention permits closely regulated exposures of great magnitude to be given without any danger of movement between, or separation of, the original and the sensitive material.

In accordance with the invention, the sensitive material and the original are held in intimate contact by an improved form of vacuum frame including a transparent platen arranged in a horizontal plane, and a tubular or similar linear source of light is caused to move back and'forth, just above the platen, to expose the desired area. The exposure format is made as large as will be needed for the largest originals, and the travel of the light source is adjusted to a shorter path for maximum efficiency and exposure speed in the case of shorter originals. To regulate the degree of exposure, the number of times the linear light source passes over the material is varied, and the traversing drive is arranged to reverse itself automatically until completion of the desired number of passes. During the exposure, the original and the sensitive material are held'in intimate contact by vacuum arrangements which ensure good contact and positively eliminate any bubbles or trapped air between the two.

A simple single control valve ensures proper cycling of the vacuum lines to accomplish this object.

With the above considerations in mind, the invention will best be understood by referring now to the following detailed specification of a preferred embodiment thereof, given by way of example and illustration, and taken in connection with the appended drawings, in which Fig. 1 is a perspective view of the apparatus as a whole.

Fig. 2 is a fragmentary enlarged view generally in side elevation looking at the left side of the machine, with certain parts shown in section.

Fig. 3 is a schematic illustration of the vacuum system of the equipment.

Fig. 4 is a complete wiring schematic of the electrical system of the machine,

Referring now to Fig. 1 of the drawings, numeral 10 designates a cabinet or the like. which will preferably contain the vacuum pump and most of the electrical control components of the equipment. On the front panel of this cabinet are grouped the principal manipulative controls for the machine. These include the main power switch 12, start and stop buttons 14 and 16 for the traversing light source carriage, a numerical dial 18 for pre-setting the number of traverses desired, a switch 20 for the vacuum pump motor, and the vacuum gauge 22. Twoposition vacuum valve 24 is for the control of the vacuum applied to the printing frame portion, and 26 is a vacuum relief valve, all to be described more particularly below.

The upper surface of cabinet it) provides a table support 28 to which is hinged or otherwise movably secured the transparent glass, preferably tempered glass, holddown plate or platen of the vacuum frame, this platen being designated by numeral 3%. Along the opposite side edges of the cabinet lit are mounted a pair of guide rails 32 and 34 for a traversing carriage generally designated by numeral 36, provided with flanged wheels such as 38 cooperating with the rails. One wheel at each end of the carriage is driven by a cross-shaft (40 in Fig. 2) powered through gearing 42 by a reversible motor 44 also upon the carriage. The bottom plate 46 of the carriage has a light slot 48 above which is supported the high intensity tubular light source 59 extending almost from end to end of the carriage. A housing or cover on the carriage, numbered 52, aids in reflecting the light downwardly through the slot, and prevents the actinic rays from reaching the operator and others. It also permits directed cooling ventilation of the tubular lamp, as by a pair of blowers supported at opposite ends of the carriage 36, the blowers being arranged to direct air inwardly from both ends of the housing 52 and over the lamp. The air escapes through the light slot 48 or other edge slots in the plate 46, and a part may escape through ventilating openings in the portion of housing 52 encompassing motor 44. The blowers are numbered 54 and 56. v Limit switches 58 and 60 are carried by the carriage to effect reversal of motor 44 when the switches are operated by suitable stops, conveniently positioned along rail 32. At least one of these stops, designated 62, is arranged to be clamped to the rail in different positions to define the length of the carriage traverse, as for different size work. The stop 64 may or may not be adjustable, and in any event it preferably takes the form of an operating cam which will control the reversing switch 58 for successive traverses but, when the last traverse has been completed, will permit the switch 58 to pass over the stop to its extreme rearward rest position, in whch carriage 36 will be out of the way of the platen 30. A rest position limit switch 66 then de-energi zes the motor completely until a new cycle of operations is commenced.

The vacuum hold-down or printing frame arrangements of the invention are an improvement on a known form of printing frame, characterized by the use of vacuum for the removal of any occluded air or pockets between the glass platen and the sheet being copied, as well as the use of vacuum for maintaining the sheet firmly against the platen. As is known, a common vacuum source may be used for the purpose. The improvements provided by this invention will best be understood by referring now to Fig. 2 of the drawings. In this figure, the carriage, lamp, housing and other parts are designated by the same numerals as in Fig. 1, as is the far rail 34. The base of the vacuum frame is a shallow pan-like casting 68 which is quite rigid and is supported as upon shelves or brackets 70 carried by the cabinet 10. The rim of the pan is sealed to the conventional rubber blanket 72 as at the rim 74, and the pan is slightly bowed upward in the region of the lateral center-line of the platen 30. The amount of this bowing is exaggerated in Fig. 2. Blanket 72 also seals to platen 30 at the rim 74, when the vacuum is applied.

A first vacuum duct 76 passes through a hermetic seal in pan 68 and communicates with the upper side of blanket 72, which means, when contact is achieved, that this duct communicates with the region between the blanket and the platen 30. A second vacuum duct 78 communicates with the space between the pan 68 and the underside of blanket 72. Numeral 80 designates an original, negative or master sheet and the sensitive material lying below it, these being held in close contact with the platen by the blanket 72 when the vacuum is applied. To avoid local distortions, the ducts 76 and 78 enter the assembly near the rim, and if desired, the surface of blanket 72 may be ribbed slightly to encourage the removal of entrapped air.

In operation, a vacuum is pulled on the lower chamber (between pan 68 and blanket 72) and simultaneously in the space between the rubber blanket and the platen 30. When this is done, no more pressure exists between the platen and the films or sheets 80 than existed under atmospheric conditions. This complete vacuum eliminates all of the air between the films and the platen and between the blanket and pan. Now the duct 76 is closed, and the duct 78 is opened to the atmosphere. The external air pressure will now force the rubber blanket up and bring the films into intimate contact with each other against the underside of the platen.

In large sizes, there will be considerable atmospheric pressure on the glass platen, with consequent danger of its breaking. To alleviate this, as well as to secure a collateral advantage, the slight upward bow in pan 68 is provided. As the vacuum is pulled, the glass platen will bow down and the pan will bow up very slightly. The initial slight clearance will be taken up, with the center of the platen supported by the pan, of course through the intermediary of the intervening layers. As the vacuum increases, the contact area between the platen and the underlying parts (supported by the pan) will slowly increase, and will have the effect of rolling out any occluded air towards the rim, for most complete elimination thereof.

The vacuum control arrangements are detailed in schematic form in Fig. 3. The vacuum pump is designated 82 and it connects with a conventional two-position valve 54 having the operating handle 24 as in Fig. 1. In the position numbered 1 vacuum is applied to both ducts 76 and 78, while in position 2 duct 76 is closed off and duct 78 is opened to the atmosphere at port 86. When the exposure is completed, the valve is returned to position 1 and the relief valve 26 is opened to permit the platen 30 to be raised. This eliminates the necessity of having to stop the vacuum pump motor after each exposure.

As has been stated, an automatic control is provided for permitting any desired number of exposure traverses of the light carriage to be effected; that is, since the carriage will always be wanted to return to its rest position at the completion of the exposure, any even number of traverses counting both directions of motion. The arrangement for providing this control will now be described in connection with Fig. 4 of the drawings, which also includes certain other wiring pertaining to the machine.

Numeral 12 in Fig. 4 designates a conventional main switch for a three-wire power supply for the apparatus. A subsidiary and lamp control switch 96, not shown in Fig. 1, and mounted on carriage 36 or the front panel, controls the application of power to contactors 92, 94 arranged to maintain the supply circuit to the lamp step-up transformer 98 so long as the switch 96 is closed. The secondary winding of transformer 98 energizes the lamp 50 directly, for example at a voltage of approximately 1,900 volts or such other value as corresponds to the lamp rating. For machine safety, the transformer secondary may be grounded to the machine frame, as shown. Blowers 54 and 56 are controlled from the same circuit, over the same switch 96, so that they will be energized whenever the lamp is on.

The power supply shown is of the three-wire -220 volt A.C. type, providing 110 volts between either conductor A or B and O, and 220 volts between conductors A and B. The latter voltage is applied only to transformer 98 for the lamp.

Subsidiary power leads 0 and A supply, through the manual vacuum-pump motor switch 20 (shown on the front panel in Fig. 1) the vacuum pump indicated at 82 (see also Fig. 3). Leads 0 and B additionally supply operating current to the reversible motor 44. When motor lead 104 is energized by the control means to be described, the motor traverses the carriage 36 forward referring to Fig. 1, while when lead- 106 is energized, the motor traverses the carriage in the opposite direction, i.e., towards its rest position. The common motor conductor returns to line 0. The start and stop buttons for carriage traverse are again designated by the same numerals, 14 and 16, used in Fig. 1. These momentary button switches control the coils 108 and 110 of a latching relay 124, of known type, so arranged that when either coil is energized, its associated contacts are latched in their operated condition and remain so until the other coil is energized. The counter mechanism by which are obtained the desired (even) number of carriage traverses will now be described. Briefly, it utilizes the multipoint manual switch 112, whose dial or control knob 18 is also so designated in Fig. 1. Switch 112 is here shown as having twenty contact points, all of which are connected to the corresponding contacts 114 of a twentypoint rotary stepping switch familiar to the automatic telephone art. This rotary switch includes, besides its contact points 114, a wiper arm 116 which steps progressively along the arcuate array of contacts in response to successive energizations of its stepping magnet coil 118. When the reset magnet coil 120 is energized, even momentarily, the wiper arm 116 is automatically restored to the zero, home or initial contact position designated by numeral 122, and to which no circuit is connected.

The positions of the various relays and contacts in Fig. 4 are those prior to energization of the start button 14, but with the manual switch 112 set on its third position to call for six traverses of the carriage, corresponding to three complete forward-and-back movements. The operation of the arrangement will be understood by tracing the circuits when the start button is now momentarily depressed, it being assumed of course that switch 12 is closed and lamp 50 up to its normal luminance, and the vacuum frame is suitably loaded. The latching relay 124 is assumed to have operated to its stop condition, as indicated by the labelled arrows on the relay contacts, as a result of completion of a prior exposure and return of the carriage 36 to its rest position, in which the rest-position limit switch 66 will be open. The rear limit switch '8 will be closed at this time, and the front limit switch 60 will be open.

When start button 14 is momentarily depressed, it will energize coil 108 of the latching relay and shift the movable contacts in the directions indicated by start. A circuit will be completed from power supply wire B, the back contact set of relay coil 110, conductor 126, the back contact 128 of the motor-reversing relay 130, and conductor 104 to the motor, energizing the same in the forward direction. The carriage 36 will start forward, and when its rear limit switch 58 passes over cam stop 64, the switch will be momentarily opened, but this will have no effect. As the carriage proceeds, its front limit switch 60 will ultimately be engaged by stop 62, and will be closed. This completes a circuit from line conductor B, contacts of relay 110, conductor 126, conductor 134, switch 60 and conductor 136 to the stepping coil 118, contacts of relay 108 and line conductor 0. The stepping coil will remain energized until switch 60 opens again as the carriage reverses, and this momentary energization of the stepping coil advances the rotary switch wiper 116 to the next contact position. Also, closure of front limit switch 60 energizes, over conductor 138, the coil of mo tor reversing relay 130, whose other terminal is permanently connected to supply conductor 0. The contact 128 of relay 130 opens, the forward motion of motor 44 stops, and as contact 140 closes, the motor is energized in the opposite direction over conductor 106. The remaining contacts associated with 128 and 140 provide good braking characteristics for the motor in a well-known way which forms no essential part of the present invention, so that detailed description thereof is deemed unnecessary.

During the return (rearward) motion of the carriage 36, front limit switch 60 remains open, and rear limit switch 58 remains closed. It is noted that when reversing relay 130 became operated as above described, its contacts 142 were also closed, completing a circuit from conductor 126, these contacts 142, lead 144, limit switch 58 and lead 138 to the coil of relay 130, to maintain the motor relay in reversed condition during the rearward travel of the carriage. Otherwise, the rearward drive motor circuit would have been opened at limit switch 60.

When the limit switch 58 engages cam stop 64 on the return trip, the switch opens and relay 13%) becomes deenergized, its contacts again reversing the carriage motor 44 to commence another forward traverse. This back and forth motion of the carriage continues until the successive actuations of stepping coil 118 bring the wiper 116 to its third position away from home contact 122, corresponding to the completion of two and a half complete traverses. Recalling that coil 108 (start) is still energized, it will be seen that a circuit is now completed from line conductor 0, lead 146, lead 148, switch 112, conductor 150, wiper 116 and the stop coil 110 of the latching relay. The contacts of the latching relay will all be operated in the opposite directions to those formerly occupied, and will remain so until the start coil is again energized. Also, the reset coil 120 will be energized to restore the wiper 116 of the stepping or rotary switch to its off or home position 122.

Notwithstanding the energization of the stop coil 110, the carriage 36 will commence its rearward motion for the last half-traverse, because the motor circuit at motor lead 106 will be maintained over lead 134 and the normally-closed rest limit switch 66, to line conductor B which circuit will not be opened until the carriage returns to its rest position out of the way of the vacuum frame. It will be noted, in this connection, that if the exposure is terminated by operation of stop button 16 before completion of the pre-set number of exposure traverses, the same condition will exist; that is, the carriage motion will not cease until the carriage has cleared the vacuum frame and returned to its rest position, regardless of the settings of stops 62 and 64.

Since the reset coil 120 has restored the rotary switch to its starting position, and since the latching relay has returned to its stop position, the apparatus is ready for a succeeding exposure of one or more traverses as soon as the start button 14 is again depressed.

While the invention has been described herein in considerable detail in the interest of ready understanding, it will be understood also that the details can be varied as desired by those skilled in the art, Without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. A contact printing machine for photosensitive materials, comprising a horizontal table support for material to be exposed, rails paralleling opposite edges of said support, a relatively narrow carriage supported between said rails for travel therealong, an elongated light source on said carriage extending lengthwise thereof, motor means for propelling said carriage in both directions along said rails, adjustable carriage position sensing devices for controlling said motor means to cause the carriage to travel back and forth across the table between selected limits of travel, counter means for registering the number of complete back-and-forth traverse movements of said carriage, and means controlled by said counter means for de-energizing said motor means to discontinue the carriage traverse motion after completion of a pre-set number of traverses.

2. A contact printing machine in accordance with claim 1, including means for maintaining said motor means energized following substantial completion of its final traverse, and means operated by the carriage for discontinuing motor energization upon its arrival at a rest position substantially beyond an edge of said support.

References Cited in the file of this patent UNITED STATES PATENTS 2,427,923 Reynolds Sept. 23, 1947 2,464,793 Cooke Mar. 22, 1949 2,739,516 Hosterman Mar. 27, 1956 2,760,419 Gelb Aug. 28, 1956 FOREIGN PATENTS 819,623 Germany Nov. 5, 1951

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