US3635559A

US3635559A - Photographic printing apparatus

Info

Publication number: US3635559A
Application number: US872867A
Authority: US
Inventors: Robert E Harrell; Edward H Parker
Original assignee: Western Litho Plate and Supply Co
Current assignee: Western Litho Plate and Supply Co
Priority date: 1969-10-31
Filing date: 1969-10-31
Publication date: 1972-01-18
Anticipated expiration: 1989-01-18
Also published as: GB1269178A; FR2066791A5; DE2052675A1; NL7015907A; BE758336A; CH518570A; CA931410A

Abstract

A photographic printing apparatus, particularly for exposing lithographic plates to light through films, in which a plate with a film thereon is applied to a conveyor at an input station and conveyed by the conveyor to a position within a vacuum frame unit at an exposure station, after which the vacuum frame is closed and evacuated for pressurizing the plate and film, the exposure is made, the vacuum frame unit is opened, and operation of the conveyor is resumed to convey the plate and film out of the vacuum frame unit to an output station for removal of the film.

Description

Harrell et al.

Jan. 18, 1972 [54] PHOTOGRAPHIC PRINTING Primary Examiner-Samuel S. Matthews APPARATUS Assistant Examiner-Richard L. Moses Attorney-Koemg, Senmger, Powers and Leavitt [72] Inventors: Robert E. Harrell, Manchester; Edward B.

Parker, Ballwin, both of Mo. [57] ABSTRACT [73] Assignee: Western Litho Plate & Supply Co., St. A photographic printing apparatus, particularly for exposing Louis, Mo. lithographic plates to light through films, in which a plate with [22] Filed: Oct. 31, 1969 a film thereon 1s applled to a conveyor at an input statlon and conveyed by the conveyor to a position within a vacuum frame [21] App]. No.: 872,867 unit at an exposure station, after which the vacuum frame is closed and evacuated for pressurizing the plate and film, the exposure is made, the vacuum frame unit is opened, and [52] US. cl ..355/85, 355/91, 355/99 operation of the conveyor is resumed to convey the plate and l (1|. ..C03b out of the acuum frame n t to an output Station for [58] Held olSearch ..355/85,87,9l,93,99,101; removalofthe mm 27 Claims, 9 Drawing Figures [56] References Cited UNITED STATES PATENTS 3,468,606 9/1969 Wolf et al. ..355/91 /35' /55 a /2 h V V2 7 5 /45 0 75 n l w 4 93 1/ 59 7 73 1/ h u 29,; I 33 35 3a i 5/ Z 3 7 A 47 4/ i (/5 45 47 PATENTEU JAN? 81972 SHEET 2 0F 7 PATENTED JAN: 81972 SHEET 3 UF 7 BACKGROUND OF THE INVENTION This invention relates to photographic printing apparatus, and more particularly to apparatus for automatically carrying photosensitive plates through an exposure operation.

The invention is particularly concerned with apparatus for automatically carrying lithographic plates such as are widely used in offset printing through an exposure operation. It will be understood that a typical lithographic plate generally comprises a thin aluminum plate having a photosensitive coating on one face thereof, e.g., a coating of a diazo compound, to be exposed to light through a film (e.g., a negative) for development of an image on the plate. Heretofore, the exposure of such plates has been typically carried out by relatively slow and cumbersome manual procedure involving manually placing a plate and film in a vacuum printing frame, manually closing the frame, exposing the plate to light through the film, manually opening the frame, and manually removing the plate and film from the frame. The present day demands, particularly in newspaper operations, for rapid processing of lithographic plates for offset printing are not readily economically met by such manual procedure.

SUMMARY OF THE INVENTION Among the several objects of this invention may be noted the provision of a photographic printing apparatus, particularly for exposing lithographic plates, adapted automatically to effect the handling of plates and films through the exposure procedure, including pressurizing of the plates and films for close contact therebetween during the exposure; the provision of such apparatus which may be used in tandem with automated plate processing equipment for developing the images on the plates; and the provision of such apparatus which minimizes the number of quality of manual operations required for reliable exposure of the plates. In general, apparatus of this invention comprises an endless conveyor which is movable intermittently to convey a plate with a film thereon from an input station, at which a plate and film are applied to the conveyor, to an exposure station, at which the plate is exposed to light through the film, and thence to an output station. A light-transmitting pressing means is provided for pressing the plate and film at the exposure station, and means is provided for mounting this pressing means for movement from an open retracted position spaced from the conveyor, to permit the conveyor to convey a plate and film from the input station to the exposure station, to a closed position for pressing the assembly at the exposure station, said pressing means being movable to its said open retracted position after exposure of a plate to permit the conveyor to move the exposed plate and film out of the exposure station to the output station. A light source is provided at the exposure station for exposing the plate at the exposure station through the film on the plate while pressed by said light-transmitting pressing means. Other objects and features will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS line 6-6 of FIG. 2, with parts broken away;

FIG. 7 is an enlarged vertical transverse section taken on line 7-7 of FIG. 2, with parts broken away;

FIG. 8 is a wiring diagram; and

FIG. 9 is a chart showing the timing of certain cam-actuated switches.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first more particularly to FIGS. 1 to 3 of the drawings, a photographic printing apparatus made in accordance with this invention is shown to comprise an endless conveyor generally designated 1 movable intermittently to convey a light-sensitive plate P with a film F thereon from an input station I, at which the plate and the film are applied to the conveyor, to an exposure station E, at which the plate is exposed to light through the film, and thence to an output station 0 for removal of the film from the plate. The apparatus is particularly useful for exposing lithographic plates having a light sensitive coating on one surface thereof, but may be used for exposing photographic plates other than lithographic plates. Generally indicated at 3 is a light-transmitting means for pressing the plate film assembly at the exposure station. Means generally designated 5 is provided for mounting this light-transmitting means for movement from an open retracted position spaced from the conveyor to permit the conveyor to convey a plate film assembly (the work) from the input station I to the exposure station E to closed position for pressing the assembly (the work) at the exposure station. A light source 7 is provided at the exposure station for exposing the work at the exposure station while the work is pressed by the light-transmitting means 3. The arrangement is such that a plate with a film thereon may be applied to the conveyor at the input station I, the conveyor then driven to convey this item of work to the exposure station E under the pressing means 3 (which is open at this time), after which the pressing means is closed, the light source activated to expose the plate to light through the film. Then, the light source is deactivated, the pressing means is opened, and the conveyor is driven to convey the exposed work out of the exposure station to the output station for removal.

The conveyor 1 comprises an elongate table designated in its entirety by the reference numeral 9 having a top 11 supported on legs 13 located at the sides of the table adjacent its four corners. The table top 11 comprises a channel 15 extending lengthwise of the table along one side thereof (its left side as viewed in the direction of travel of the plate-film assemblies), and a channel 17 extending lengthwise of the table along its other side. These channels are positioned with their webs horizontal and their flanges extending downward, the legs 13 being welded to the outside of the outside flanges of the channels. Braces 19 extend between the legs at the sides of the table, and braces 21 extend between the legs at its ends. A sheet metal table top plate 23 horizontally spans the channels at the input station I and a sheet metal table top plate 25 horizontally spans the channels at the output station 0. These table top plates are generally coplanar and their inner ends 23a and 25a are spaced apart to provide a gap therebetween at the exposure station. The side edges of the

plates

23 and 25 are spaced inward from the outer sides of the channels.

The conveyor 1 further comprises a pair of endless chains each designated 29 having horizontal upper reaches 29a. These chains are arranged for travel of said horizontal upper reachs 29a lengthwise of the table above the

channels

15 and 17 outward of the side edges of the

plates

23 and 25. The chains are trained around sprockets 31 on a horizontal drive shaft 33 at the output station end of the table (which may he referred to as its forward end) and around s rockets 35 on a horizontal idler shaft 37 at the input station and (the rearward end) of the table. Shaft 33 extends transversely of the table, being joumaled in bearings 39 carried by brackets as indicated at 41 on the

channels

15 and 17 at their forward ends. it is adapted to be intermittently driven for forward feed of the upper reaches of the chains via a chain drive 43 from an electric gearmotor 45. Shaft 37 extends transversely of the table, being joumaled in bearings 47 carried by brackets as indicated at 49 on the channels at their rearward ends. The upper reaches 29a of chains 29 are guided for travel along the channels and 17 by tracks 51 on the channels. Extending between the chains at equally spaced intervals along their length are flat bars 53, the ends of these bars being secured to the chains with the bars in position for travel flatwise over the

table top plates

23 and 25 contiguous to the latter. Each bar has means thereon for attachment thereto of a plate P and a film F with the plate and film in proper register. As shown in FIGS. 2 and 5, this means comprises a pair of pins 55 on the bar, the plate P and film F each having a pair of holes such as indicated at 57 adjacent one edge thereof for receiving the pins, the holes being located for proper registry of the film with the plate when the plate and the film are applied to the pins.

The pressing means 3 is constituted by a vacuum frame unit comprising a window assembly 59 having a light-transmitting panel 61, and a flexible resilient presser pad 63 below the window assembly, adapted for vacuum pressing of a plate and a film therebetween (see especially FIGS. 6 and 7). The pad 63, which may comprise a relatively thick slab of a relatively closed-cell foam rubber, for example, is mounted on a sheet metal bottom plate 65 spanning the

channels

15 and 17 in the gap between their inner ends 23a and 25a at the exposure station. The side edges of the plate 65 and pad 63 are spaced inward from the outer sides of the channels, like the

plates

23 and 25. The pad is cemented airtight to the bottom plate 65 all around its margin as indicated at 67, the portion of the pad bounded by the cement being free of the bottom plate so that is is adapted to flex upward from the bottom plate under a vacuum condition as will appear. Normally, the top surface of the pad is generally flush with the top surfaces of the

table top plates

23 and 25.

The window assembly 59 is mounted in an open rectangular frame generally designated 69 for up and down movement relative to the frame. The frame 69 is normally located in horizontal position overlying the table top and spaced above the table top at the exposure station, the spacing being sufficient to allow for passage of a plate P with a film F thereon along the table top underneath the frame. The frame comprises side angle bars 71 and 73 (71 being at the left and 73 at the right) which extend longitudinally with respect to the table and two flat end bars each designated 75 which extend transversely with respect to the table. Bars 75 are disposed vertically. The frame 69 is pivoted for swinging movement on a horizontal axis extending longitudinally of the table at the left side of the table by means of hinges such as indicated at 77 each having one leaf secured to the outside of channel 15 and the other secured to bar 71. It normally rests in horizontal position as shown in FIG. 7 extending across the table, its right side angle bar 73 bearing on stops 79 extending up from the right side channel 17, and is adapted to be swung up from this position when desired to open it away from the table top, springs 81 being provided to counterbalance its weight plus that of the window assembly 59 and other components carried thereby.

The window assembly 59 comprises an open rectangular window frame 83, the light-transmitting panel 61 being secured at the bottom of this frame 83 by clips 85 with a gasket 87 interposed therebetween to provide an airtight seal between the frame 83 and the panel 61. The latter may consist of a relatively rigid panel of any suitable light-transmitting plastic, or a pane of glass. The window assembly 59 is mounted for vertical movement in the frame 69, and means indicated generally at 89 is provided for moving it vertically relative to the frame 69 between a raised retracted position relative to the presser pad 63 and a closed position wherein a peripheral sealing strip 91 adhered to the bottom of panel 61 is in sealing engagement with the pad. When the window assembly 59 is in its raised retracted position, the sealing strip 91 is spaced above the upper surface of pad 63 for passage of a bar 53 and work moving with the bar.

The means 89 for vertically moving the window assembly 59 in the frame 69 includes a pair of cam plates each designated 93 guided for sliding movement transversely of the frame 69 on the inside of bars 75 of the frame by means of guides 95 secured to bars 75. The cam plates are interconnected for conjoint movement by an angle bar 97 which extends between the ends of the cam plates adjacent the side angle bar 71 of frame 69. An air cylinder 99 is secured to bar 71 extending laterally outward therefrom. A piston rod 101 extends from a piston (not shown) in cylinder 99 to a connection at 103 with bar 97. Operation of cylinder 99 is controlled by a solenoid valve V. The arrangement is such that on extension of the piston rod from cylinder 99, the cam plates 93 are moved in the direction away from bar 71 toward bar 73 and when the piston rod is retracted into the cylinder, the cam plates are retracted back toward bar 71. Each cam plate has a pair of inclined cam slots 105. Extending up from each of the two transversely extending sides of the window frame 83 of window assembly 59 are two lugs each designated 107. Shafts 109 at the upper end of these lugs carry cam follower rollers 111 slidable in these inclined slots. These shafts also carry rollers 113 slidable in vertical slots 115 in the bars 75 guiding the window frame 83 for vertical movement relative to the bars 75. The cam slots 105 are so angled that when cam plates 93 are moved in the direction away from bar 71 (toward the right as viewed in FIG. 7), the window assembly 59 is moved down to its closed position wherein sealing strip 91 engages the presser pad 63, and when cam plates 93 are moved back toward bar 71, the window assembly is raised to its retracted position.

The presser pad 63 has an opening 117 therethrough (inward of its cemented margin 67) constituting a vacuum port, and is provided with a fitting 119 on its bottom for this port with a vacuum line 121 connected between this fitting and the inlet of a vacuum pump 123 driven by an electric motor 125 (see FIG. 1).

Extending up from bars 75 are posts 127 carrying bars 129 supporting the light source 7, which may be a high-intensity light source such as an Ascor ADDALUX light source made by Berkey Technical Corporation of Woodside, New York. Bars 129 are vertically adjustable on the posts as indicated at 131 and the light source is adjustable on the bars 129 as indicated at 133. The light source is ofa type which has an exposure lamp which is continuously energized during the working period and a shutter, exposure intervals being determined by the opening and closing of the shutter. It has a blower 135 on top thereof.

A microswitch 137 is mounted underneath the table plate 23 at the input station I and has its operating arm 139 projecting upward through an opening 141 in plate 23 for engagement by a lithographic plate P placed on plate 23 (see FIGS. 2 and 5). A microswitch 143 is mounted at the output or exit end of the table 9 in position for raising of its operating arm 145 by a bar 53 as it reaches the exit end of the table top plate 25 at the unloading station U. I

Now, referring to FIG. 8, the control circuit for the apparatus is shown to include five latching relays denoted lLR-SLR, two timing relays denoted lTR and 2TR, a variable timing relay denoted VTR, and two control relays denoted 1CR and 2CR. Each of the five latching relays has a lower coil denoted by the letter D, an upper coil denoted by the letter U (e.g., the lower coil of lLR is lLRD and the upper coil of lLR is ILRU). Each of the five latching relays is of a type having contacts associated with its upper coil, designated lLRD-l, for example, and contacts associated with its upper coil, designated lLRV-l, for example, and as to which all its contacts are latched in one position on energization of the lower coil and remain latched in that position on deenergization of the lower coil, becoming latched in their other position on energization of the upper coil and remaining latched therein on deenergization of the upper coil.

A pushbutton switch lPB is connected in series with the lower coil lLRD of relay lLR and contacts 4LRD-l (shown closed) of relay 4LR in a line 151 across line L1 and neutral line N of a three phase 230 volt power supply circuit, the third line of this circuit being indicated at L2. A main switch 18 is provided in lines L1 and L2. A lamp PO is connected in a line 153 across lines L2 and N to indicate that power is on when switch 1S is closed. A switch 155 is connected in series with the coil of relay 2CR in a line 157 across L1 and N. This switch 155, when open, provides for automatic cycling of the apparatus and when closed to energize relay 2CR provides for manual operation. Contacts 4LRD-2 (shown closed) of relay 4LR are connected in series with a lamp R in a line 159 across L1 and N. The solenoid valve V is connected in series with contacts lCR-l (shown closed) of relay 1CR and a normally open cam-actuated switch 1CS-3 in a line 161 across L1 and N. The switch 1CS-3 is one of seven cam-actuated switches lCS-l, 1CS-2, lCS-3, 1CS-4, 1CS-5, lCS-8, and 1CS-9 actuated by timing cams on a timer shaft (not shown) driven by a timer motor 1CS.

Contacts SLRD-l (shown open) of relay SLR are connected in series with coil VTRC of relay VTR in a line 163 across L1 and N. Relay VTR has a motor VTRM and normally closed contacts VTR-l connected in series in a line 164 shunted around its coil VTRC. Relay VTR is adapted, via its motor VTRM, to time out the exposure interval. Normally open contacts VTR-2 of relay VTR and the upper coil SLRU of relay SLR are connected in series in a line 165 across L1 and N. Contacts 5LRD-2 (shown closed) of relay SLR, contacts 2LRD-1 (shown open) of relay 2LR and the motor 1CS for driving the timer shaft carrying the timing .cams which actuate the seven lCS switches are connected in series in a line 167 across L1 and N. Switch 143 and the brake coil 1MB of the conveyor drive motor 45 are connected in series in a line 169 across L1 and N. Coil 1MB when deenergized applies a brake to the motor shaft, and releases the brake when energized. Cam switch lCS-l (which is normally open) is con nected in series with motor 45 in a line 171 across L1 and N. Lines 169 and 171 are interconnected as indicated at 173 so that the coil 1MB and motor 45 are in parallel.

Contacts 4LRU-l (shown open) of relay 4LR are connected in series with an off cycle" lamp CC (to indicate that a cycle is off) in a line 175 across L1 and N. Contacts 4LRU-2 (shown open) of relay 4LR are connected in series with the coil of timing relay 2TR in a line 177 across L1 and N. Normally closed contacts 2CR-1 of relay 2CR, contacts 3LRD-1 (shown open) of relay 3LR and the coil 4LRU of relay 4LR are connected in series in a line 179 across L1 and N. Cam-actuated switch 1CS-9 (which is normally closed), contacts 3LRD-3 (normally open) of relay 3LR, contacts 2LRU-1 of relay 2LR and the upper coil 2LRU of relay 2LR are connected in series in a line 181 across L1 and N. The upper coil SLRU of relay 3LR is connected in a line 183 in shunt with the upper coil 2LRU of relay 2LR. Cam-actuated switch 1CS-8 (which is normally open) contacts 3LRU-1 (normally closed) of relay 3LR and a counter 185 are connected in series in a line 187 across L1 and N. Normally open contacts lTR-l of relay lTR, normally open contacts 1370 of switch 137 and the lower coil 2LRD of relay 2LR are connected in series in a line 189 across L1 and N. Normally closed contacts 137s of switch 137, cam-actuated switch 1CS-2 (which is normally open) and the lower coil 3LRD of relay 3LR are connected in series in a line 191 in parallel with contacts 1370 and the lower coil 2LRD of relay 2LR.

The upper coil lLRU of relay lLR is connected in a line 193 in parallel with the lower coil 3LRD of relay SLR. Normally closed contacts lTR-Z of relay lTR, normally open contacts 2CR-2 of relay 2CR and a lamp 0 to indicate ON are connected in a line 195 in parallel with contacts 137C, contacts lCS-2 and the lower coil 3LRD of relay 3LR.

Contacts lLRD-l (shown open) of relay lLR, normally closed contacts 2CR-3 of relay 2CR, contacts 1LRD-2 (shown open) of relay lLR and the coil of relay lTR are connected in series in a line 197 across L1 and N. Lines 195 and 197 are interconnected as indicated at 199. Normally open contacts ZTR-l of relay 2TR and the lower coil 4LRD of relay 4LR are connected in series in a line 201 across L1 and N. Contacts 3LRU-1 (shown open) of relay 3LR and the coil of relay lCR are connected in series in a line 203 across L1 and N. Cam-actuated switch lCS-S, normally closed contacts lCR-2 of relay lCR and the lower coil SLRD of relay 5LR are connected in series in a line 205 across L1 and N.

The motor for driving the vacuum pump is connected in series with normally closed contacts lCR-3 or relay lCR and with cam-actuated switch 1CS-4 (which is normally open) in a line 207 across lines L2 and N. The lamp 209 of the light source 7 has a control 211 in a circuit 213 including contacts lLRU-l (shown closed) of relay lLR, normally closed contacts 2CR-4 of relay 2CR, contacts 1LRU-2 (shown open) of relay lLR and normally open contacts 2CR-5 of relay 2CR. The lamp 209, once turned on, remains on and the light source 7 has a shutter (not shown) which is electrically opened to expose a plate at station E for a predetermined interval under control of the variable timing relay VTR. Lines L1, L2 and N are connected to the input 215 of the light source 7 as indicated at 217. Normally open contacts VTRl of relay VTR are connected in a circuit 219 for a shutter actuator 221.

Operation is as follows:

For automatic cycling of the apparatus (i.e., for automatically feeding one plate after another through the apparatus) main switch 15 is closed and switch is open. With 18 closed, lamp PO is energized to indicate the power is on. Latch relays 1LR, 2LR, 3LR and SLR will have previously had their upper coils U energized and their contacts accordingly are set as shown in FlG. 8. Latch relay 4LR will have previously had its lower coil D energized and its contacts accordingly are set as shown in FIG. 8. The window assembly 59 is in its raised retracted position. Lamp R is energized to indicate that the apparatus is ready to start cycling. A first lithographic plate P with a film F thereon is placed on the table top plate 23 at the input station I, and attached to the bar 53 which is about to enter the exposure station E. The plate P holds down the operating arm 139 of switch 137 (see FIG. 5) so that contacts 1370 of this switch are open and contacts 1370 are closed.

The pushbutton switch lPB is momentarily closed, resulting in energization of the lower coil lLRD of latch relay lLR.

This closes contacts lLRD-l and lLRD-2 in line 197, and opens contacts lLRU-l and closes contacts lLRU-Z in circuit 213. The efl'ect of opening lLRU-1 and closing lLRU-2 is to energize the exposure lamp 209. Closure of lLRD-l and 1LRD-2 in line 197 energizes the coil of timing relay lTR (contacts 2CR-3 being closed), and energizes lamp 0 to in dicate that the apparatus has been turned on.

After its built-in time delay interval(e.g., 1 minute), relay lTR closes its contacts lTR-l in line 189 and opens its contacts 1TR-2 in line 195. On closure of contacts lTR-l in line 189 and assuming that contacts 1370 of switch 137 are closed via a lithographic plate P on table plate 23 at the input station l holding down arm 139 of switch 137, the lower coil 2LRD of latch relay 2LR is energized, closing contacts 2LRD1 in line 167 and contacts 2LRU-1 in line 181. On closure of contacts 2LRD-1 in line 167, timing motor ICS is energized to drive the timer shaft which carries the cams for actuating the seven lCS switches.

The operation of the cam switches is shown in FIG. 9. Referring thereto, it will be seen that lCS-l is closed at 2 seconds of running time of motor lCS from the start of motor lCS, and opened at 5 seconds. Switch 1CS-2 is closed at 2% seconds and opened at 4 seconds of running time of motor 1CS. Switch 1CS-3 is closed at 8 seconds and opened at 22% seconds of running time of motor 1CS. Switch 1CS-4 is closed at 8 seconds and opened at 22 seconds. Switch 1CS-5 is momentarily closed at 20 seconds. Switch 1CS-8 is closed at 22% seconds and opened at 22% seconds. Switch 1CS-9 is closed at 23 seconds and opened at one-fourth s second of running time.

On closure of switch 1CS-l (in line 171), motor 45 is energized to drive the conveyor chains 29 and move bars 53 forward, thereby pulling the lithographic plate P with film F thereon forward from the input station l into the exposure station E. As soon as the bar 53 which was under operating arm 145 of switch'143 at the exit end of the table top plate 25 moves out from under this arm, switch 143 (in line 169) closes to establish a holding circuit for motor 45 via line 173. Switch lCS-l opens at seconds, but motor 45 remains energized via said holding circuit until it is broken by the opening of switch 143 when the next bar 53 comes under the switch operating arm 145. This occurs at about 7 seconds of elapsed time, and at this point the first lithographic plate P with the film F thereon has been advanced from the input station I completely into the exposure station E under the window assembly 59, ready for lowering of the latter for pressurizing the plate P and film F.

At 2% seconds of elapsed running time of motor lCS, switch lCS-2 closes and remains closed until the 4th second, but has no effect at this time since contacts 137s of switch 137 in line 191 with switch lCS-2 are open due to the first lithographic plate P continuing to hold down arm 139 of switch 137.

At 8 seconds of elapsed running time of motor lCS, switches lCS-3 (in line 161) and lCS-4 (in line 207) close. With lCS-3 closed in line 161, and contacts lCR-l closed, solenoid valve V is energized to actuate air cylinder 99 to extend piston rod 101 and lower the window assembly 59 to its closed position wherein sealing strip 91 engages the presser pad 63 all around the first plate P and film P which have been pulled into the exposure station E. With switch 1CS-4 closed in line 207 and contacts 1CR-3 closed, motor 125 is energized to drive the vacuum pump 123 to draw a vacuum in the sealed chamber defined by the light-transmitting panel 61, strip 91 and presser pad 63, in which is received the first lithographic plate P with the film F on top. As a consequence of drawing the vacuum in this chamber, pad 63 is pressed upward by atmospheric air pressure on its bottom, thereby to press the stated first plate P and film F against the light-transmitting panel 61, so that the plate is made ready for exposure. Plate 65 has a central hole 65a for entry of air to pass against the bottom of the pad.

At seconds, cam switch lCS-S (in line 205) closes momentarily, and with contacts lCR-Z in line 205 closed, the lower coil SLRD of latch relay SLR is energized to close contacts SLRD-l (line 163) and to open contacts SLRD-2 (line 167). With contacts SLRD-l closed, the coil VTRC and motor VTRM of the variable timing relay VTR are energized. On opening of contacts 5LRD-2 in line 167, the timing motor ICS is deenergized. On energization of coil VTRC, contacts VTR-l of relay VTR close in circuit 219 to effect actuation of shutter actuator 221 to open the shutter of the light source 7, thereby exposing the lithographic plate P at the exposure station to light from lamp 209 through the light-transmitting panel 61 and the film F under pressed flat conditions of the plate and film.

The motor VTRM of the variable timing relay VTR times out the exposure interval, at the termination of which contacts VTR-J in line 164 open to stop motor VTRM and contacts VTR-2 in line 165 close to energize the upper coil SLRU of relay SLR. This opens contacts SLRD-l in line 163 and closes contacts 5LRD2 in line. 167. Opening of contacts SLRD-l deenergizes relay coil VTRC. Closing of contacts SLRD-Z in line 167 restarts the timing motor 1C8 (contacts ZLRD-l being closed at this time). Opening of contacts VTR! in circuit 219 causes the shutter to close and terminate the exposure.

At 22 seconds of elapsed running time of motor lCS, switch lCS-4 opens thereby deenergizing the motor 125 to stop the vacuum pump 123.

At 22% seconds, switch lCS-3 opens to deenergize the solenoid valve V and actuate the air cylinder 99 to retract piston rod 101 and raise the window assembly 59 to its retracted position clear of the plate and film at station E. This enables exit of the exposed plate P and the film F thereon from the exposure station E. Switch lCS-8 is closed from 22% to 22% seconds to energize the counter 185 (contacts 3CRU-1 being closed at this time).

The timing motor lCS continues to run through 0 and at 2 seconds of running time from 0, switch lCS-l closes, starting the motor 45 to resume operation of the conveyor 1. Shortly after the motor 45 starts, and the bar 53 which was under the operating arm 145 of switch 143 moves out from under this arm, switch 143 (in line 169) closes to establish the holding circuit for motor 45 via line 173. Switch lCS-l opens at 5 seconds, but motor 45 remains energized via said holding circuit until it is broken by the opening of switch 143 when the next bar 53 comes under the arm 145. This occurs at about 7 seconds, and at this point the exposed lithographic plate P with the film F thereon has been pulled forward out of the exposure station and onto the table top plate 25 at the output station 0. The exposed plate and the film may then be removed from table top plate 25. it is contemplated that the film may be removed from the exposed plate as by means of a vacuum cup lifter, and the exposed plate fed directly ahead to a plate processing apparatus.

Assuming that a second plate P to be exposed and a film F were applied to table top plate 23 at the input station land attached to the bar 53in position to enter the exposure station E during the dwell of the bars 53 after entry of the first plate P and film thereon into the exposure station, the second plate P with a film F thereon is pulled into the exposure station when the first plate and film are pulled out of the exposure station to the output station and the above-described operations are repeated for exposing the second plate P and then pulling it forward out of the exposure station to the output station.

The apparatus continues to cycle automatically as above described as long as plates P are applied one after another to the table top plate 23 at the input station during successive dwells of the conveyor 1. The last plate P with a film-F to be applied is carried through an exposure operation and pulled out to the output station 0, and then the apparatus stops due to the operating arm 139 of switch 137 moving up and opening contacts 137a and closing contacts 1370 of switch 137 when the last plate P is pulled forward from input station I to exposure station E. With these contacts so set, on the last cycle of operation of timing motor lCS, switch lCS-2 closes at 2% seconds energizing the upper coil lLRU of latch relay lLR (in line 193) and the lower coil 3LRD of latch relay 3LR (in line 191). Contacts lLRU-2 in circuit 213 open to deenergize the exposure lamp 209. Contacts lLRD-l (line 197) open to deenergize relay lTR placing its contacts back in starting position. Closure of contacts 3LRD-l (line 179) results in energization of the upper coil 4LRU of latch relay 4LR and attendant closure of contacts 4LRU-l (line 175 and 4LRU-2 (line 177). On closure of contacts 4LRU-1 in line 175, lamp 0C is energized to indicate that the apparatus is off cycle." On closure of 4LRU-2 in line 177, the coil of timing relay 2TR is energized to start its timing interval (which may be 2 minutes, for example). Contacts 2TR1 (line 201) remain closed to maintain the lower coil 4LRD of latch relay 4LR energized and thus maintain contacts 4LRD-1 open for this interval. Thus, even though switch lPB may be actuated before the end of this interval, relay ILR will not be energized and, accordingly, exposure lamp 209 cannot be energized until after this interval. Also, on. energization of coil 3LRD, contacts 3LRU-2 (in line 203) close to energize the coil of relay lCR. Contacts lCR-l (line 161), lCR-Z (line 205) and lCR-3 (line 207) open, thus preventing solenoid valve V. and the motor for driving the vacuum pump 123 from being energized and also preventing stopping of timing motor lCS at 20 seconds. The conveyor drive motor 45, in operation as a result of switch lCS-l having closed at 2 seconds, functions to pull the last plate P out of the exposure station E to the output station 0, and is deenergized when the bar 53 pulling this plate actuates operating arm of switch 143. At 23 seconds, switch 1CS-9 (in line 181) closes, energizing the upper coils ZLRU and 3LRU of latch relays ZLR and 3LR. Contacts 2L- RU-l (line 181) and 2LRD-1 (line 167) open, thus deenergizing timing motor lCS. Contacts 3LRD-1, 3LRD-2, 3L- RU-l and liLRU-Z all return to their starting position. The coil of relay lCR is deenergized so that its contacts return to starting position.

lnthe event only one plate is fed through the apparatus with switch 155 set for automatic cycling (open), the plate goes through as above described and the apparatus stops in the same manner as above described for the last plate of a succession of plates fed through the apparatus.

For manual operation, e.g., for feeding only one plate through the machine, switch 155 (in line 157) is closed. This energizes the coil of relay 2CR. Contacts ZCR-S in circuit 213 close to energize the exposure lamp 209. A warmup period (e.g., 1 minute) should be allowed for the lamp 209 to warm up before starting to feed work through the apparatus. The contacts of the other relays will be as shown in FIG. 8, and lamps PO and R will be on to indicate that power is on and that the apparatus is ready.

A plate P with a film F thereon is placed on the table top plate 23 at station I and attached to the bar 53 at station I. Then, push button switch lPB is momentarily closed. This energizes the lower coil lLRD of latch relay lLR, closing contacts lLRD-l and 1LRD-2 (line 197) to energize lamp to indicate the operation is on, and to energize the lower coil ZLRD of relay ZLR via lines 199 and 195 (contacts 2CR-2 and 1370 being closed). Contacts ZLRD-l close to energize the timing motor 1138. Switch 1CS1 closes at 2 seconds to energize the motor 45 to drive the conveyor 1. with switch 143 closing to establish a holding circuit for the motor when the bar 53 which was under arm 145 of switch 143 moves out from under the arm. Switch lCS-l opens at 5 seconds, but motor 45 remains energized via said holding circuit until it is broken by the opening of switch 143 by the next bar 53 coming under the arm 143. This occurs at about 7 seconds. At this point, the plate! with film F thereon is in the exposure station E At 8 seconds, switches lCS-3 (in line 161) and 1CS-{4 (in line 207) close, resulting (as before) in energizstion of solenoid valve V to lower the window assembly 59 and in energization of motor 125 to drive vacuum pump 123 to draw a vacuum for pressurizing of the plate and film.

I At 20 seconds, cam switch 1CS-5 (in line 205) is momentarily closed (as before) to effect energization of coil VTRC and motor VTRM of variable timing relay VTR, and deenergization of motor lCS. This effects opening of the shutter of light source 7 (as before) to expose the plate P. When motor VTRM has timed out the exposure interval, contacts VTR-l (line 164) open as before to stop the motor and deenergize the coil VT RC of relay VTR, and to restart the timing motor lCS.

With motor lCS again in operation. at 2.2 seconds, switch 1CS-4 opens to deenergim the vacuum pump motor 125.

At 22% seconds, switch 1C8 opens for raising of window assembly 59 (as before)- Motor lCS continues to run through 0, and at 2 seconds switch lCS-l closes, starting motor 45 to resume operation of conveyor 1 (as before). This pulls the exposed plate P and the film F thereon out of exposure station E to the output station D, motor 45 stopping when the bar 53 exiting from station E comes under arm 145 and actuates switch 143.

At 2% seconds, switch lCS-Z closes, energizing the upper coil lLRU of latch relay ILR (in line 193) and the lower coil 3LRD oflatch relay 3LR (in line 191). Contacts ILRD-1 (line 197) thereupon opento extinguish the ()N" lamp 0. Also. contacts ;LBU-Q (line 203,) close to energize relay ICR. with resulting opening of contacts lCll-l (line 161), lCR-Z (line 205) and 1CR3 (line 207) to prevent energizetion of solenoid valve V and motor 125 and also to prevent stopping of motor lCS (as before).

At 23 seconds, switch lCS-Q (in line 181) closes, to effect stopping of motor 168 and return of the contacts of latch relay SLR and the contacts of relay ICR to their starting position, as before.

It is possible to cfi'ect continued feeding of plates P to be exposed through the apparatus with switchin its manual setting (i.e., closed), by applying a plate P and film F to the conveyor] at input station I during each dwell of the conveyor (thus actuating switch 137), but, in distinction to automatic continued feeding as above described, when the last plate P has been fed through the apparatus, the exposure lamp 209 is not automatically deenergized.

From the above, it will appear that the apparatus is adapted automatically to handle plates P and films F through the expo sure procedure, simply by applying a plate and a film to the conveyor 1 (i.e., attaching the plate and film to a bar 53 via pins 55 or other suitable means) during the dwell interval of the conveyor. The film may be lifted away from the exposed plate at station 0, and the exposed plate fed forward away from station 0 to an automatic plate processor. The switch 137 functions to detect whether or not a plate has been applied to the conveyor 1 at the input station I, and stops the operation of the apparatus if a plate has not been applied thereto after completing the exposure of a plate at the exposure station E and the conveyance of the latter plate to the output station 0.

in view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. Apparatus for exposing photosensitized plates comprising an endless conveyor having an upper reach movable in a predetermined path and a lower return reach. means for intermittently driving the conveyor intermittently to convey a plate carried by said upper reach together with a film on the upper face of said plate along said path from a first station at which the plate and film may be applied to the conveyor to a second station at which the plate is exposed to light through the film and thence to a third station, means for pressing the plate and film at the second station, said pressing means comprising means movable upwardly and downwardly above said upper reach adapted to be raised from the upper reach to permit the conveyor to move a plate with a film thereon from the first to the second station and to move an exposed plate with a film thereon out of the second station to the third station, and adapted to be lowered for pressing a plate and film at the second station for exposure of the plate while the conveyor is stopped, and a light source for exposing the plate at the second station to light through the film while pressed by said pressing means.

2. Apparatus for exposing photosensitized plates comprising an endless conveyor movable intennittently to convey a plate with a film thereon from a first station at which the plate and film may be applied to the conveyor to a second station at which the plate is exposed to light through the film and thence to a third station, means for pressing the plate and film at the second station, said means being adapted to be opened to permit the conveyor to move a plate with a film thereon from the first to the second station and to move an exposed plate with a film thereon out of the second station to the third station, and adapted to be closed for pressing a plate and film. at the second station for exposure of the plate while the conveyor is stopped, and a light source-for exposing the plate at the second station to light through the film while pressed by said pressing means. and control means acting automatically to close said. pressing means when the conveyor has moved a plate with a film thereon from the first to the second station andthen acting to operate said light source to expose the plate at the second station for an exposure interval.

3. Apparatus as set forth in claim 2 wherein the control means acts automatically to open said pressing means on completion of exposure of a plate at the second station, and

then acts to operate the Conveyor for an interval to move the exposed plate with a film thereon out of the second station to the third station.

4. Apparatus as set forth in claim 3 wherein said control means includes means for varying the length of the exposure interval.

5. Apparatus as set forth in claim 3 wherein the conveyor is adapted to bring another plate with a film thereon from the first to second station when it is operated for its said interval, and wherein said control means acts automatically to close said pressing means when the conveyor stops at the end of its said interval and then acts to operate said light source to expose the plate at the second station for an exposure interval.

6. Apparatus as set forth in claim 5 wherein said control means includes means for detecting whether or not a plate has been applied to the conveyor at the first station and stopping operation of the apparatus if a plate has not been applied.

7. Apparatus as set forth in claim 6 wherein said plate-detecting means acts to stop the apparatus after completion of exposure of the plate at the second station and conveyance of the latter plate to the third station.

8. Apparatus as set forth in claim 1 wherein said pressing means when closed forms a vacuum chamber and wherein means is provided for evacuating said chamber.

9. Apparatus for exposing photosensitized plates comprising an endless conveyor movable intermittently to convey a plate with a film thereon from a first station at which the plate and film may be applied to the conveyor to a second station at which the plate is exposed to light through the film and thence to a third station, means for pressing the plate and film at the second station, said means being adapted to be opened to permit the conveyor to move a plate with a film thereon from the first to the second station and to move an exposed plate with a film thereon out of the second station to the third station, and adapted to be closed for pressing a plate and film at the second station for exposure of the plate while the conveyor is stopped, and a light source for exposing the plate at the second station to light through the film while pressed by said pressing means, said pressing means comprising a light-transmitting panel movable between an open retracted position and a closed position engaging the film on the plate at the second station.

10. Apparatus as set forth in claim 9 wherein said panel when closed forms a vacuum chamber and wherein means is provided for evacuating said chamber.

11. Apparatus for exposing photosensitized plates comprising an endless conveyor movable intermittently to convey a plate with a film thereon from a first station at which the plate and film may be applied to the conveyor to a second station at which the plate is exposed to light through the film and thence to a third station, a flexible presser pad at the second station, the plate with the film thereon being conveyed from the first station onto said pad, a light-transmitting panel above the pad, means mounting said panel for movement between a raised retracted position spaced from the pad and a lowered closed position in peripheral sealing engagement with the pad forming a vacuum chamber, means for evacuating said chamber for pressing of the plate and film in said chamber by the pad against the panel for exposure of the plate, said panel when in retracted position permitting the conveyor to move a plate with a film thereon from the first station onto the pad at the second station and to move an exposed plate and the film thereon off the pad and out of the second station to the third station, and a light source for exposing the plate at the second station to light through the film thereon via said panel while pressed against said panel.

12. Apparatus as set forth in claim 11 having control means for automatically raising said panel on completion of exposure of a plate at the second station and then operating the conveyor for an interval to move an exposed plate with a film thereon off the pad and out of the second station to the third station.

13. Apparatus as set forth in claim 12 wherein the control means acts automatically to lower said panel when the conveyor has moved a plate with a film thereon onto the pad at the second station, then acts to operate said evacuating means, and then acts to operate said light source to expose the plate at the second station for an exposure interval.

14. Apparatus as set forth in claim 13 wherein the control means acts automatically to stop the operation of said evacuating means and to raise said panel on completion of exposure of a plate at the second station, and then acts to operate the conveyor for an interval to move the exposed plate with a film thereon off the pad and out of the second station to the third station.

15. Apparatus as set forth in claim 14 wherein the conveyor is adapted to bring another plate with a film thereon from the first station onto the pad at the second station when it is operated for its said interval, and wherein said control means acts automatically to lower said panel when the conveyor stops at the end of its said interval, then acts to operate said evacuating means, and then acts to operate said light source to expose the plate at the second station for an exposure interval.

16. Apparatus as set forth in claim 15 having means for detecting whether or not a plate has been applied to the conveyor at the first station and stopping operation of the apparatus if a plate has not been applied.

17. Apparatus as set forth in claim 16 wherein said plate-detecting means acts to stop the apparatus after completion of exposure of the plate at the second station and conveyance of the latter plate to the third station.

18. Apparatus as set forth in claim 11 wherein said conveyor comprises a pair of endless chains having upper reaches extending along opposite sides of said pad, and bars extending transversely between said chains spaced at intervals along their length, each of said bars having means thereon for attachment of a plate and film thereto.

19. Apparatus as set forth in claim 18 having a tabletop member at the first station and a tabletop member at the third station, the pad being between said tabletop members and generally flush with the top surfaces thereof, the bars passing over said tabletop members and said pad.

20. Apparatus as set forth in claim 19 wherein said lighttransmitting panel is mounted for up and down movement in a frame spanning the apparatus above the pad at the second statron.

21. Apparatus as set forth in claim 20 wherein the light source is carried by means extending up from said frame.

22. Apparatus as set forth in claim 20 having cam means actuated by an air cylinder on said frame for moving said panel up and down.

23. Apparatus as set forth in claim 22 having an electric motor for driving said conveyor, a solenoid valve controlling said air cylinder and control means for actuating said valve to cause said cylinder to raise said panel on completion of exposure of a plate at the second station and then energizing said motor to operate the conveyor for an interval to move an exposed plate out of the second station to the third station and to bring another plate with a film thereon from the first to the second station, and including a switch operable by a bar of said conveyor as it brings a plate to the third station for deenergizing said motor to stop the conveyor, and means for actuating said valve to cause said cylinder to close said panel when the conveyor stops and then operating said light source to expose the plate at the second station for an exposure interval.

24. Apparatus as set forth in claim 23 having a switch with an operating arm projecting up through an opening in the table top member at the first station for detecting whether or not a plate has been applied to the table top member at the first station and stopping operation of the apparatus if a plate has not been applied.

25. Apparatus as set forth in claim 24 wherein said plate-detecting switch acts to stop the operation of the apparatus after completion of exposure of the plate at the second station and conveyance of this plate by the conveyor to the third station.

26. Apparatus for exposing photosensitized plates comprising conveyor means movable intermittently to convey a plate from a first station at which the plate may be applied to the conveyor means to a second station at which the plate is exposed to light through a film and thence out of the second station, means for pressing the plate and film atthe second station, said pressing means being adapted to be opened to permit the conveyor means to move a plate from the first to the second station and to move an exposed plate out of the second station, and adapted to be closed for pressing a plate and film at the second station for exposure of the plate while the conveyor means is stopped, a light source for exposing the plate at the second station to light through the film while pressed by said pressing means, and control means acting automatically to close said pressing means when the conveyor means has moved a plate from the first station to the second station, and then acting to operate said light source to expose the plate through the film at said second station for an exposure interval.

27. Apparatus for exposing photosensitized plates comprising an endless conveyor movable intermittently to convey a plate from a first station at which the-plate may be applied to the conveyor to a second station at which the plate is exposed to light through a film and thence out of the second station, a flexible presser pad at the second station, the plate being conveyed from the first station onto said pad, a light-transmitting panel above the pad, means mounting said panel for movement between a raised retracted position spaced from the pad and lowered closed position in peripheral sealing engagement with the pad forming a vacuum chamber, means for evacuating said chamber for pressing of the plate and film in said chamber by the pad against the panel for exposure of the plate, said panel when in retracted position permitting the conveyor to move a plate from the first station onto the pad at the second station and to move an exposed plate off the pad and out of the second station, and a light source for exposing the plate at the second station to light through the film thereon via said panel while pressed against said panel.

* i i t

Claims

1. Apparatus for exposing photosensitized plates comprising an endless conveyor having an upper reach movable in a predetermined path and a lower return reach, means for intermittently driving the conveyor intermittently to convey a plate carried by said upper reach together with a film on the upper face of said plate along said path from a first station at which the plate and film may be applied to the conveyor to a second station at which the plate is exposed to light through the film and thence to a third station, means for pressing the plate and film at the second station, said pressing means comprising means movable upwardly and downwardly above said upper reach adapted to be raised from the upper reach to permit the conveyor to move a plate with a film thereon from the first to the second station and to move an exposed plate with a film thereon out of the second station to the third station, and adapted to be lowered for pressing a plate and film at the second station for exposure of the plate while the conveyor is stopped, and a light source for exposing the plate at the second station to light through the film while pressed by said pressing means.

2. Apparatus for exposing photosensitized plates comprising an endless conveyor movable intermittently to convey a plate with a film thereon from a first station at which the plate and film may be applied to the conveyor to a second station at which the plate is exposed to light through the film and thence to a third station, means for pressing the plate and film at the second station, said means being adapted to be opened to permit the conveyor to move a plate with a film thereon from the first to the second station and to move an exposed plate with a film thereon out of the second station to the third station, and adapted to be closed for pressing a plate and film at the second station for expOsure of the plate while the conveyor is stopped, and a light source for exposing the plate at the second station to light through the film while pressed by said pressing means, and control means acting automatically to close said pressing means when the conveyor has moved a plate with a film thereon from the first to the second station and then acting to operate said light source to expose the plate at the second station for an exposure interval.

3. Apparatus as set forth in claim 2 wherein the control means acts automatically to open said pressing means on completion of exposure of a plate at the second station, and then acts to operate the conveyor for an interval to move the exposed plate with a film thereon out of the second station to the third station.

20. Apparatus as set forth in claim 19 wherein said light-transmitting panel is mounted for up and down movement in a frame spanning the apparatus above the pad at the second station.

26. Apparatus for exposing photosensitized plates comprising conveyor means movable intermittently to convey a plate from a first station at which the plate may be applied to the conveyor means to a second station at which the plate is exposed to light through a film and thence out of the second station, means for pressing the plate and film at the second station, said pressing means being adapted to be opened to permit the conveyor means to move a plate from the first to the second station and to move an exposed plate out of the second station, and adapted to be closed for pressing a plate and film at the second station for exposure of the plate while the conveyor means is stopped, a light source for exposing the plate at the second station to light through the film while pressed by said pressing means, and control means acting automatically to close said pressing means when the conveyor means has moved a plate from the first station to the second station, and then acting to operate said light source to expose the plate through the film at said second station for an exposure interval.

27. Apparatus for exposing photosensitized plates comprising an endless conveyor movable intermittently to convey a plate from a first station at which the plate may be applied to the conveyor to a second station at which the plate is exposed to light through a film and thence out of the second station, a flexible presser pad at the second station, the plate being conveyed from the first station onto said pad, a light-transmitting panel above the pad, means mounting said panel for movement between a raised retracted position spaced from the pad and lowered closed position in peripheral sealing engagement with the pad forming a vacuum chamber, means for evacuating said chamber for pressing of the plate and film in said chamber by the pad against the panel for exposure of the plate, said panel when in retracted position permitting the conveyor to move a plate from the first station onto the pad at the second station and to move an exposed plate off the pad and out of the second station, and a light source for exposing the plate at the second station to light through the film thereon via said panel while pressed against said panel.