US 3310304 A
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March 21, 1967 P. FOIAS ETAL. 333G304 I SHUT FEED DEFLECTOR AND INTERRUPTER RESPONSIVE TO PHOTOELECTRIC SHEE'I POSITION SENSING MEANS Filed Feb. 28, 1966 2 Sheets-Sheet l IN ENTORSI PA VEL Poms GHEORGHE EWA CHE BY DAV/D BEfiGMA/V ATTORNEY.
March 21, 1967 P. FOIAS ETAL SHUT FEED DEFLECTOR AND INTERRUPTER RESPONSIVE TO PHOTOELECTRIC SHEET POSITION SENSING MEANS 2 Sheets-Sheet 2 Filed Feb. 28, 1966 IIIIH INVENTORSI PA VE' L F OIA 5 GHEORGHE E/VA CHE DA V/D BERG/WAN United States Patent SHEET FEED DEFLECTOR AND INTERRUPTER RESPONSIVE T0 PHOTOELECTRIC SHEET POSI- TION SENSING MEANS Pavel Foias, Gheorghe Enache, and David Bergman, Bucharest, Rumania, assignors to Comitetnl de Stat Pentru Cnltura si Arta, Bucharest, Rumania, a corporation of Rumania Filed Feb. 28, 1966, Ser. No. 530,626 5 Claims. (Cl. 27157) This application is a continuation-in-part of our copending application Ser. No. 351,145, now abandoned, filed Mar. 11, 1964.
Our present invention relates to a sorting device for a printing plant, designed to determine by photoelectric means the correct feeding of a succession of single sheets of paper to a printing cylinder and to deviate improperly positioned and/or superposed sheets from their normal path.
In a printing plant it is customary to feed the blank sheets tangentially to the printing cylinder, carrying the usual form on its periphery, and to urge the sheet against the rotating form with the aid of a counterpressure roller, the form being concurrently brushed by an inking roller or the like ahead of its point of contact with the sheet.
Photoelectric systems adapted to divert improperly positioned (e.g. oblique or overlapping) sheets are known per se. If such systems are placed in the feed path of a printing cylinder along with the sheets, normally advance in timed relationship with the rotation of the cylinder, deviation of one or more sheets from their path would normally cause the cylinder to perform a corresponding number of revolutions without interposition of a paper layer between the form and the counterpressure roller. This,
that the latter would smudge the rear surface of the next 'sheet delivered to the cylinder.
An object .of our invention, therefore, is the provision of means for preventing such smudging without the need for stopping the printing cylinder upon a diversion of an improperly placed sheet, thus enabling continuous operation of the printing press.
This object is realized, in accordance with our invention, by the provision of photoelectric detector means which, in a manner known per se, produce a defect signal in response to improper positioning of an oncoming sheet, in combination with electromagnetic release means controlled thereby to disengage the pressure roller from the printing cylinder upon the occurrence of such signal, the operation of the release means coinciding with that of a sorter whose sheet-deflecting position is maintained for the remainder of an operating cycle of the printing press, i.e. to the end of the cylinder revolution then in progress.
The photoelectric detector means advantageously includes a combination of photocells designed in part to scan the edges of oncoming sheets, for the purpose of ascertaining any oblique positioning thereof with reference to the direction of advance along the guide path, and in part to sense the occurrence of sheet duplications, the two cell assemblies being connected in parallel to the input of an associated control circuit whose output includes suitable electromagnetic devices, such as solenoids, for operating the sheet deflector and the release mechanism for the pressure roller. A timer, such as a set of cams mechanically coupled with the driven printing cylinder, insures the maintenance of the operative condition of these electromagnetic devices for the duration of a cylinder revolution. This timer may also be used, according to another feature of our invention, for the purpose of disabling the photoelectric detectors-especially the edgeice scanning cells thereofduring part of a cycle so that the test of correct alignment of a sheet with its guide path will be made only at specified intervals to avoid the generation of false defect signals.
The invention will be described in greater detail with reference to the accompanying drawing in which:
FIG. 1 is a perspective view of a portion of a printing press, including a set of supervisory photocells disposed along a guide path for paper sheets to be successively fed to a printing cylinder: and
FIG. 2 is an overall circuit diagram of the system shown partly in FIG. 1.
As illustrated in FIG. 1, there is provided a guide path for a succession of sheets 30, this guide path including the base plate 40 bounded by rails 31 between which the sheets are advanced by suitable feed means such as one or more pairs of transport rollers (not shown). A photoelectric detector 1, disposed midway along the width of the plate 40, senses the simultaneous passage of two or more superposed sheets While two other detectors 2 and 3, flanking detector 1, determine the parallelism of an oncoming sheet 30 with reference to the rails 31. At a location just beyond the detector assemblies 1-3, a set of rocker arms 16 are swingably mounted on a common shaft 15. The plate 40 terminates ahead of the region of the arms 16 so that the latter can swing with their rearwardly pointing ends below the level of that plate to pick up the leading edge of any sheet to be deviated from its normal path of travel toward a printing cylinder. In the absence of a defect signal from any of the photocells 1-3, however, the tips of the arms 16 are raised above that level so that the sheets can pass unhindered onto a series of conveyor bands 41 which are driven by a pulley 42 via a belt 21 from a source of motive power partly visible at 43. The undeflected sheets are transported, as indicated at 30', toward a printing cylinder 33 with a form 44 and a cooperating pressure roller 37 which are shown diagrammatically in FIG. 2.
Beyond the rocker arms 16 there is another shaft 20, driven by the belt 21, with a set of feed rollers 17, some of these rollers co-operating wtih counter rollers 18 which are supported by rods 45 on a manually rotatable shaft 46. When the arms 16 are swung downwardly (e.g. counterclockwise) under the control of photocells 13, they direct an oncoming sheet into the nip of rollers 17 and 18 which deliver such sheet to a receptacle 19 as shown at 30". The rocking of the arms 16 is accomplished by a solenoid 13 which is connected with the rocker shaft 15 via a lever 14 and two articulated links 38, 39.
Reference will now be made to FIG. 2 for a description of the circuitry associated with the photoelectric detector assemblies 1-3 and the solenoid 13. Each of these assemblies includes a source of light, respectively designated 1a, 2a and 311, as well as an associated photocell 1b, 2b and 3b, respectively. Plate 40 is longitudinally slitted at 1c, 20 and 30 (FIG. 1) to permit light from the lamps 1a, 2a, 3a, which may be disposed underneath the plate, to reach the associated photocells 1b, 2b, 3b. Photocell 1b is so biased as to remain conductive whenever light from its lamp 1a reaches it directly or through a single interposed paper layer; only in the presence of at least two superposed sheets 30 will the resistance of cell 1b increase sufficiently to apply positive bias to the control grid of a pentode 4 which is connected in parallel with a similar pentode 5 in the operating circuit of a relay 6. Whereas the control grid of tube 4 is tied to the anode of photocell 1b, the corresponding grid of tube 5 is connected to the cathodes of cells 2b and 3b in parallel so that the latter tube will conduct whenever either of these photocells is illuminated by the associated light a source 2a or 3a in the absence of an intervening sheet. The energizing circuit of light sources 2a and 3a, however, includes a normally open switch 26 which is closed only periodically under the control of a cam 27 synchronized with the printing cylinder 33.
The plate voltage for tubes 4 and is derived from an alternating-current source 34 via a transformer 35 and a conventional rectifying network 36. A secondary winding 35a of transformer 35 supplies current to the lamps 1a, 2a and 3a.
Also connected across power source 34 are a relay 8 in series with a make contact 7 of relay 6; a solenoid in series with a make contact of relay 8; a relay 12 in series with another make contact 11 of relay 8 and with a switch contact 22 which is controlled by a cam 23 also synchronized with cylinder 33; and the solenoid 13 in series with a break contact 24 of relay 12. The latter relay further has a holding contact 25 and an additional make contact 47 in parallel with contact 9.
A condenser 48, connected across the Winding of relay 6, delays the release thereof upon the establishment of conduction to either of tubes 4 and 5. By a conventional sheet stopper, not shown, the advance of the sheets 30 along the guide path illustrated in FIG. 1 may be regulated so that a sheet will pass the monitoring assemblies 13 at a time just when the cam-controlled switches 22 and 26 are about to close. If only a single sheet, symmetrically disposed with reference to the detectors 1-3, passes the control point, and its lateral edges are substantially parallel to the guide rails 31, the photocells 2b and 3b will be shielded from their light sources while the cell 1b will continue to conduct; underthese circumstances, the tubes 4 and 5 remain cut oif and the relay 6 is not operated. Printing proceeds then in the normal manner.
If, however, the cell 112 is obscured by the superposition of two or more sheets, and/or a sheet is positioned obliquely or olf-center so that one or the other cell 215, 3b will be illuminated, relay 6 will operate to energize the relay 8 and, via armature 9 of the latter, relay 12 which locks over its holding contact 25 in series with cam switch 22 and by its break contact 24 de-energizes the normally actuated solenoid 13 connected with lever 14. A spring 49 now swings this lever counterclockwise to rock the arms 16 (FIG. 1) into their sheet-deflecting position. Solenoid 10, initially energized by contact 9 of relay 8, is maintained operative by contact 47 of relay 12 independently of the state of energization of relays 6 and 8 until the cam 23 has completed its revolution to reopen the switch 22 and to release the relay 12.
Relay armature 47 could be omitted if condenser 48 is chosen large enough to maintain the relay 6 energized throughout the portion of an operating cycle during which the form 44 moves past the roller 37, this roller being normally urged by a spring 50 against the cylinder 33. It will be apparent that smudging of the roller 37, and therefore of a subsequently arriving paper sheet, will not occur as long as the roller bears only upon the cylinder periphery not occupied by the form 44.
Manually operable switches, not shown, may be provided for the purpose of deactivation of one of the other detector assembly 1 or 2, 3.
1. In a printing plant having a form-carrying printing cylinder and a co-operating pressure roller for holding a sheet to be printed against the periphery of said cylinder upon rotation of the latter, the combination therewith of guide means forming a path for sheets to be successively fed to said cylinder, photoelectric detector means at said path for sensing the position of said sheets and producing a defect signal in response to an improper positioning thereof, sorting means controlled by said detector means for deflecting improperly positioned sheets from said path in response to said signal, electromagnetic release means controlled by said detector means for temporarily disengaging said pressure roller from said cylinder in response to said signal, said release means being provided with circuit means for maintaining said roller disengaged from said cylinder, independently of said detector means, for at least a major portion of an operating cycle, and timer means coupled with said cylinder for maintaining said sorting means in a sheet-deflecting position for the remainder of an operating cycle during which said signal is emitted by said detector means.
2. The combination defined in claim 1 wherein said circuit means includes relay means, energizing means for said relay means responsive to said signal, and capacitive means for maintaining said relay means energized beyond the duration of said signal.
3. The combination defined in claim 1 wherein said circuit means includes contacts controlled by said timer means.
4. The combination defined in claim 1 wherein said detector means comprises a pair of edge-scanning assemblies positioned along opposite sides of said path for concurrent triggering by a properly positioned sheet, and switch means controlled by said timer means for rendering said assemblies triggerable only during a predetermined portion of an operating cycle.
5. The combination defined in claim 4 wherein said detector means further comprises a duplication-detecting assembly positioned substantially centrally along said path for triggering by a pair of superposed sheets.
References Cited by the Examiner UNITED STATES PATENTS 2,072,235 3/1937 Wormser 27l57 2,072,236 3/1937 Wormser 27l57 2,556,895 6/1951 Baker 27 l47 2,947,917 8/1960 OBrien 27l57 X 3,026,419 3/1962 Aweida et a1. 27l57 X 3,186,708 6/1965 Hinz 27l57 M. HENSON WOOD, JR., Primary Examiner.
ALLEN N. KNOWLES, Examiner,