US3779162A

US3779162A - Copy sheet distinguishing device for rotary offset printing machines

Info

Publication number: US3779162A
Application number: US00241704A
Authority: US
Inventors: T Ogawa; T Hasegawa
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 1969-09-08
Filing date: 1972-04-06
Publication date: 1973-12-18
Anticipated expiration: 1990-12-18
Also published as: DE2044487C3; DE2044487A1; DK138309C; DK138309B; DE2044487B2; GB1280241A; JPS4923005B1

Abstract

A copy sheet distinguishing device for rotary offset printing machines having a copy sheet feed device of the type in which the copy sheet feed operation is automatically controlled. The copy sheet distinguishing device controls the automatic copy sheet feed device such that the latter acts also as a marker copy sheet feed device, inserting copy sheet markers between successive groups of printed copy sheets for one master plate each time a predetermined number of copy sheets have been printed from one of a series of masterplates successively mounted on the master cylinder, so that rapid distinguishing between several groups of printed copy sheets can be facilitated after the completion of duplication of a predetermined number of master plates. A logic control circuit is disclosed including a first pulse generator responsive to the printing of a copy sheet and a second pulse generator responsive to each revolution of the master cylinder, which signals are used to affect control of the copy sheet feed device to provide printed copy sheets and marker copy sheets from the same stack.

Description

United States Patent Ogawa et a1.

[451 Dec. 18, 1973 [75] Inventors: Toshiya Ogawa, Tokyo; Toru Hasegawa, Kawasaki, both of Japan [73] Assignee: Ricoh Co. Ltd., Tokyo, Japan [22] Filed: Apr. 6, 1972 [21] Appl. No.: 241,704

Related US. Application Data [63] Continuation-in-part of Ser, Nov 67,056, Aug. 26,

. 1970, abandoned.

[301 Foreign Application Priority Data Sept. 8, 1969 Japan 44/7145) [52] US. Cl ..101/142,101/148,101/232, 101/425 [51] Int. Cl. B4lf 7/06, B41f 35/06 [58] Field of Search l01/l36 l45, 32 33,142.51. 7

[56] References Cited UNlTED STATES PATENTS 3,447,456 6/1969 Giuiuzza 101/183 3,457,857 7/1969 Burger 101/232 X 3,650,204 3/1972 Burger 101/91 X 3,056,346 lO/1962 Gammeter et a1. 101/144 3,102,470 9/1963 Cragg et a1. 101/233 x 3,195,456 7/1965 Charwood et a1, 101/184 2,813,484 11/1957 Pratt 101/144 3,264,981 8/1966 Burger et a1. lOl/l44 3,412,676 11/1968 Tonkin et a1. 101/144 Primary Examiner-J. Reed Fisher Attorney-Henry T. Burke et a1.

[57] ABSTRACT A copy sheet distinguishing device for rotary offset printing machines having a copy sheet feed device of the type in which the copy sheet feed operation is automatically controlled. The copy sheet distinguishing device controls the automatic copy sheet feed device such that the latter acts also as a marker copy sheet feed device, inserting copy sheet markers between successive groups of printed copy sheets for one master plate each time a predetermined number of copy sheets have been printed from one of a series of masterplates successively mounted on the master cylinder, so that rapid distinguishing between several groups of printed copy sheets can be facilitated after the completion of duplication of a predetermined number of master plates. A logic control circuit is disclosed including a first pulse generator responsive to the printing of a copy sheet and a second pulse generator responsive to each revolution of the master cylinder, which signals are used to affect control of the copy sheet feed device to provide printed copy sheets and marker copy sheets from the same stack.

11 Claims, 18 Drawing Figures AIENIEIIIIEIJ I 8 I975 3.779.162

SIIEETlIIF 9 a CORY SHEET FEEDING EACH PRINTED COPY b- SHEET PULSE GENERATING I PRINTED COPY SHEET C NUMBER COUNTING d FRINTING COMFLETION NO JDDGING i YES TIMER CLEANING COPY SHEET FEED ACTUATION INSTRuCTION TERMINATION INSTRUCTION CORY CLEANING SHEET FEED TERMINATION I INSTRUCTION INSTRUCTIO COPY SHEET FEED SOLENOID ACTUATION I .%Y SH ET E V FEED TERMINATION PULSE GENERATING COPY SHEET FEED SOLENOID DE-ACTUATION COPY SHEET MARKER FEED TERMINATION INSTRUCTION SOLENOID FOPY SHEET FEED DE-ACTUATION PATENTEUBEC18 I975 3.779.152

SHEET 20F 9 FIG. 2

8 UCEREHEET FEED CHECKING CIRCUIT COPY SHE T gb gg COUNTER CIRCUIT FEED CONTROL CIRCUIT f RRINTINO T COMPLETION JUDGING CIRCUIT a I 5 I CLEANING COPY SHEET FEED I I I TIMER lNSTRUCTION |N$TRUCT|QN T L CIRCUIT CIRCUIT I CIRCUIT I I 7 S E 'i E COPY SHEET DEVICE FEED SOLENOID 21! COPY SHEET MARKER I OOIC CONTROL CIRCUIT l I l [COPY SHEET MERI ER CHECKING CIRCIT PATENTEU DEC 1 8 I975 SHEH i [If 9 PATENTEUDEC 1 8 ms SBEEI 5 Bf 9 E NF @FOZ PATENTEU DEC 18 I973 SHEET 8 BF 9 I FIG. 6

FIG

PATENIED DEC 1 8 i973 SHEET 7 BF 9 FIG. 9

FIG. l3

COPY SHEET DISTINGUISHING DEVICE FOR ROTARY OFFSET PRINTING MACHINES CROSS REFERENCE This is a continuation-in-part of our co-pending application Ser. No. 67,056, filed Aug. 26, 1970, now abandoned, with claim of priority based on Japanese application No. 71459/69, filed Sept. 8, 1969.

BACKGROUND OF THE INVENTION In the operation of rotary offset printing machines, a stack of copy sheets printed from a plurality of master plates, contains groups of printed copy sheets and increases in height as the printing operation progresses. Heretofore, it has been customary to place one or two sheets of paper or cards (hereinafter referred to as a copy sheet markers) between the groups of printed copy sheets piled in a stack to distinguish between the printed copy sheets duplicated from different master plates when a predetermined number of copy sheets have been duplicated from each master plate. The presence of the copy sheet markers in the stack of printed copy sheets is readily discernible as the operator looks sideways at one side of the stack, thereby facilitating distinguishing between one group of printed copy sheets for one master plate and another group of printed copy sheets for the next following master plate.

It has hitherto been required to attach to an offset printing machine an additional device exclusively for inserting such copy sheet markers between different groups of printed copy sheets. This renders the construction of the printing machine complex and naturally stands in the way of obtaining an overall compact size in an offset printing machine and reducing the cost of such machine in view of the space in the machine occupied by such copy sheet marker insertion device.

SUMMARY OF THE INVENTION This invention has as its object the provision of a novel copy sheet distinguishing device for rotary offset printing machines which obviates the disadvantages of the prior art that hampers full realization of advantages accruing from a low cost, an overall compact size and a simple construction which are inherent in printing machines of this type.

This object is accomplished in the present invention by using the copy sheet feed device of the rotary offset printing machine as a part of the copy sheet distinguishing device and permitting the same to function concurrently as such. More specifically, a few copy sheets, which are customarily fed additionally between the blanket cylinder and the impression cylinder for cleaning the former after a predetermined number of copy sheets have been duplicated from one master plate and before the ink image of the next following master plate is formed on the blanket cylinder, are also used as copy sheet markers in the present invention. Thus, the invention eliminates the need to use special copy sheet markers and hence an additional device for inserting such markers between different groups of copy sheets printed from different master plates.

According to this invention, a simple device comprising logic circuits and other means constitute the other part of the copy sheet distinguishing device. Such device performs the function of placing the copy sheets used for cleaning the blanket cylinder or a stack of printed copy sheets as copy sheet markers each time a predetermined number of copy sheets have been duplicated from one master plate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart diagrammatically showing the operation of the copy sheet distinguishing device for rotary offset printing machines according to this invention;

FIG. 2 is a block diagram of the copy sheet distinguishing device;

FIG. 3 is a schematic view of a rotary offset printing machine incorporating therein the copy sheet distinguishing device according to this invention;

FIG. 4a, FIG. 4b and FIG. 4c are circuit diagrams of the electric circuit used in the rotary offset printing machine of FIG. 3;

FIG. 5 is a circuit diagram showing one embodiment of the copy sheet distinguishing device according to this invention;

FIG. 6 is a schematic view of one portion of the copy sheet distinguishing device according to this invention;

FIG. 7 is a plan view of the impression cylinder of the rotary offset printing machine of FIG. 3;

FIG. 8 is a sectional view, on an enlarged scale, taken along the line X-X of FIG. 7 and seen in the direction of arrows;

FIG. 9 to 12 are side views of a portion of the rotary offset printing machine of FIG. 3;

FIG. 13 is a perspective view of a portion of the rotary offset printing machine of FIG. 3; and

FIG. 14 to FIG. 16 are side views of a portion of the rotary offset printing machine of FIG. 3.

DESCRIPTION OF A PREFERRED EMBODIMENT Before giving a detailed explanation of the invention, we should like to summarize in general terms the operation of a rotary offset printing machine. If a master plate is mounted on the master cylinder, an etching operation and an inking operation are performed successively to form on the blanket cylinder an ink image of the master plate which is transferred to copy sheets to duplicate a predetermined number of copy sheets from the master plate. When a predetermined number of copy sheets have been printed from one master plate, the master plate is replaced by the next following master plate and the same process is repeated after the ink image of the previous master plate is removed from the blanket cylinder by cleaning it with a few copy sheets additionally fed and the copy sheets used for cleaning purposes are discarded. During the time one master plate after another are successively duplicated, printed copy sheets are piled in a stack on the printed copy sheet tray until a predetermined number of copy sheets are duplicated from a plurality of master plates. Rotary offset printing machines of the type described above are known.

The present invention as incorporated in a printing machine of the type described will be first described in general with reference to the flow chart of FIG. 1 and the block diagram of FIG. 2. when one master plate is mounted on the master cylinder, a counter circuit 1 is set at a desired number of copy sheets to be printed from such master plate. In a step a, one copy sheet is fed from a copy sheet feed device and the ink image of the master plate formed on the blanket cylinder is transferred to the copy sheet to convert it into a printed copy sheet. In a step b, a pulse is produced by a pulse generator 2 and supplied to counter circuit 1 through an AND circuit 3 each time a single copy sheet is fed from the copy sheet feed device so that the number of copy sheets fed is counted by counter circuit 1 in a step c. In a step d, it is determined by a printing completion judging circuit 4 whether the number counted by counter circuit 1 has reached the number at which counter circuit 1 has been set. While the number of copy sheets fed or the copy sheets printed has not reached the desired number, a copy sheet feed logic control circuit 5 supplies its output to AND circuit 3 to keep it open. At the same time, an output of copy sheet feed logic control circuit 5 is supplied to a copy sheet feed instruction circuit 6 which gives a copy sheet feed instruction to a copy sheet feed solenoid 7, so that a copy sheet is fed from the copy sheet feed device for duplicating the same. Steps a to a' are repeated till a predetermined number of copy sheets are printed from the master plate mounted on the master cylinder. If the copy sheet feed device fails to operate even if a copy sheet feed instruction is given during these steps, no pulse will be produced by pulse generator 2 and no output will therefore be supplied from AND circuit 3 to counter circuit 1, so that the counter circuit will not perform a counting operation.

The output of AND circuit 3 is supplied to a copy sheet feed checking circuit 8 which keeps a check on whether a copy sheet is fed without fail each time an output of AND circuit 3 is supplied thereto. When no copy sheet is fed, copy sheet feed checking circuit 8 supplies its output to copy sheet feed logic control circuit 5 which supplies an output signal to copy sheet feed instruction circuit 6 which upon receipt of such signal, gives a copy sheet feed instruction to copy sheet feed solenoid 7 so that a copy sheet may be fed from the copy sheet feed device.

When the number of copy sheets printed from the master plate mounted on the master cylinder has reached the number at which counter circuit 1 is set, judging circuit 4 judges the finishing of printing and supplies an output signal to copy sheet feed logic control circuit 5 in a step e which gives a copy sheet termination instruction to solenoid 7 which is de-energized in a step fto thereby terminate copy sheet feed from the copy sheet feed device.

At the same time, the output signal ofjudging circuit 4 is supplied to both a cleaning instruction circuit 9 and a timer circuit 10, so that a cleaning instruction is given by cleaning instruction circuit 9 to a cleaning operation device 11 in a step g which actuates a cleaning device to clean the blanket cylinder with a cleaning solution to remove the ink image therefrom.

As soon as the master plate is removed from the master cylinder by the output signal ofjudging circuit 4, an ink supply to the master plate is stopped. In a step h, timer circuit 10 operates for a predetermined time interval following the receipt of the output signal from judging circuit 4 before supplying its output to a copy sheet marker logic control circuit 12. Cleaning instruction circuit 9 continues to produce a cleaning instruction signal for a predetermined time interval upon receipt of the output signal of judging circuit 4, and thereafter gives a cleaning termination instruction to cleaning device 11 in a step i which de-actuates the cleaning device. Accordingly, cleaning instruction circuit 9 can also be actuated by the output signal of timer circuit 10 as shown by broken lines in FIG. 2.

As soon as the output signal of timer circuit 10 is removed, copy sheet marker logic circuit 12 is actuated to supply an output signal to copy sheet feed circuit 6. This causes a copy sheet feed instruction to be given, in a step], from copy sheet feed circuit 6 to copy sheet feed solenoid 7, so that the latter is energized in a step k to cause copy sheets to be fed from the copy sheet feed device to the blanket cylinder. The copy sheets fed in this way for cleaning purposes are placed on a stack of printed copy sheets after being used to clean the blanket cylinder.

In a step I, a pulse is supplied from pulse generator 2 to a copy sheet marker checking circuit 14 through another AND circuit 13 each time one of the copy sheets is fed for cleaning purposes as aforementioned. In case there is an error in feeding the copy sheets, no pulses are produced by the pulse generator.) The pulse, which is considered to be a copy sheet feed termination pulse, is supplied to copy sheet marker checking circuit 14 which supplies an output signal to copy sheet marker logic control circuit 12, the latter standing by when it does not receive this signal till copy sheets are fed and giving a copy sheet marker feed termination instruction to copy sheet feed instruction circuit 6 in a step m upon receipt of this signal, so that circuit 6 produces a copy sheet feed termination instruction.

Thus, in a step n, copy sheet solenoid 17 is deenergized to terminate the copy sheet feed. Copy sheet marker logic control circuit 12 continuously supplies an output signal to AND circuit 13 to keep the latter open from the time cleaning is finished till the time copy sheet feed is terminated. It is to be understood that copy sheet marker checking circuit 14 is not essential and may be provided only if its provision is deemed necessary. In other words, the output of AND circuit 13 may be supplied direct to copy sheet marker logic control circuit 12.

The copy sheet distinguishing device according to this invention will now be described in concrete form with reference to FIG. 3 to FIG. 16. As shown in FIG. 3 and FIG. 4a, the master cylinder 110, blanket cylinder 111 and impression cylinder 112 which are of the same diameter are driven, through a gearing and from an electric motor, in the directions of arrows at the same rate as the motor is actuated upon operation of a main switch (not shown). When they start rotating, master cylinder 110, blanket cylinder 111 and impression cylinder 112 are spaced apart from one another. Operation of the main switch also causes an ink ductor roller 21 to reciprocate between an ink fountain roller 22 and an oscillator roller 23 so as to transfer ink 25 in an ink fountain 24 to oscillator roller 23 through ink fountain roller 22 and transfer roller 21. At the same time, a water ductor roller 26 is periodically brought into and out of engagement with oscillator roller 23 so as to supply water 28 in a water tank 27 to oscillator roller 23 through an immersion roller 29 and water ductor roller 26. The supply of ink and the supply of water are successively delivered to oscillator roller 23 through

rollers

22, 21, 29 and 26. Oscillator roller 23 is adapted to supply a mixture of ink and water to inking rollers 30 and 31 forming ink. Parts 21 to 31 constitute an inking device 32 as is well known.

If a start switch 33 shown in FIG. 4a is turned on, a master plate mounting relay RAl, which is connected to a direct current source El through start switch 33, a normally closed contact RA2-b of a relay RA2 shown in FIG. 5 and a normally closed contact RY-b ofa relay RY shown in FIG. 5 in series with one another, will be actuated to close normally open contacts RAl-al and RA1-a2 thereof. Since normally open contact RAl-al is connected to shunt with start switch 33, relay RAl is self-held. Actuation of relay RAl causes a master plate feed roller to be driven for rotation, so that an uppermost master plate of a stack of master plates 36 piled on a master plate feed tray is supplied to master cylinder 110 to be mounted thereon.

The uppermost master plate is supplied to master cylinder 110 while being guided by guide plates 37 and 38 and has its leading end portion gripped by grip claws 39 attached to master cylinder 110 whereby the master plate is mounted on the master cylinder. When the master plate is guided by guide plates 37 and 38, a switch 40 has its movable contact pressed by the master plate so that switch 40 is closed. Switch 40 is connected to direct current source E1 through an etching relay RA3, a normally closed contact RA4-b1 of an inking relay RA4 and the normally closed contact RY-b of relay RY in series with one another, so that closing of switch 44 actuates etching relay RA3.

Upon actuation of etching relay RA3, its normally open contact RA3-a1 which is connected in shunt with start switch 40 is closed, so that relay RA3 is self-held. Actuation of etching relay RA3 energizes a solenoid 41 having a movable shaft which is connected through a spring 42 to an end portion of a lever 43. Lever 43 which supports an immersion roller 44, a ductor roller 45 and an etching roller 46 in contact with one another is normally urged by the biasing force of a spring 47 connected between lever 43 and a fixed part to pivot to a position in which it is in contact with a stopper 48 to move etching roller 46 away from master cylinder 110.

Upon energization of solenoid 41, lever 43 is pivoted counter clockwise in FIG. 3 to bring etching roller 46 into engagement with the master plate mounted on master cylinder 110, and rollers 44 to 46 are rotated to supply an etching solution in an etching solution tank 49 to the master plate on master cylinder 110 to perform an etching operation. Parts 41 to 50 constitute an etching device 51 as is well known.

On the other hand, a resistor R1 and a capacitor C1 are connected in series with direct current source El through the normally closed contact RY-b of relay RY as shown in FIG. 4 while a normally closed contact RA- 3-b2 of relay RA3 is connected in shunt with capacitor C1. Connected to the junction between capacitor C1 and resistor R1 is a cathode of a constant voltage diode ZDl whose anode is connected to a base of an NPN type transistor TRl whose collector is connected to a positive terminal of direct current source E1 through a resistor R2 and the normally closed contact RY-b of relay RY in series with one another, and whose emitter is connected to a base of another NPN type transistor TR2. An emitter of transistor TR2 is connected to a negative terminal of direct current source E1, and a collector thereof is connected to the positive terminal of direct source E1 through an inking relay RA4 and the normally closed contact RY-b of relay RY in series with one another and at the same time to the negative terminal of direct current source E1 through a normally open contact RA4-a1 of inking relay RA4.

Thus, when etching relay RA3 is not actuated, capacitor Cl is short-circuited through a normally closed contact EA3-b2 of relay RA3. However, when actuation of etching relay RA3 opens its normally closed contact RA3-b2, capacitor C1 is charged from direct current source El through resistor R1. The charge of capacitor C1 reaches a predetermined level after lapse ofa predetermined time interval following actuation of etching relay RA3 and fires constant voltage diode ZDl, thereby turning on transistor TRl and hence transistor TR2 to actuate inking relay RA4.

Actuation of inking relay RA4 results in its normally closed contact RA4-bl being closed, so that relay RA4 is self-held. At the same time, its normally closed contact RA4-bl is opened to de-actuate etching relay RA3, so that etching device 51 is rendered inoperative. Actuation of inking relay RA4 further renders inking device 32 operative, so that inking rollers 30 and 31 are brought into engagement with the master plate mounted on master cylinder to deliver a supply of formed ink to the master plate.

A resistor R2 and a capacitor C2 are connected to direct current source E1 threough the normally closed contact RY-b of relay RY in series with one another while a normally closed contact RA4-b2 of inking relay RA4 is connected in shunt with capacitor C2. Connected to the junction between resistor R2 and capacitor C2 is an anode of a constant voltage diode ZD2 whose anode is connected to a base of another NPN type transistor TR3 whose collector is connected to the positive terminal of direct current source El through a resistor R3 and the normally closed contact RY-b of relay RY in series with one another, and whose emitter is connected to a base of a transistor TR4. An emitter of transistor TR4 is connected to the positive terminal of direct current source El through the nomrally open contact RAl-a2 of relay RAl, a relay RAS and the normally closed contact RY-b of relay RY in series with one another.

Thus, when inking relay RA4 is de-actuated, capacitor C2 is short-circuited through the normally closed contact RA4-b2 or relay R04. However, when inking relay RA4 is actuated, its normally closed contact RA- 4-b2 is opened so as to charge capacitor C2 from direct current source E1 through resistor R2. The charge of capacitor C2 reaches a predetermined level after lapse of a predetermined time interval following actuation of inking relay RA4 and fires constant voltage diode ZD2, thereby turning on transistor TR3 and hence transistor TR4 to actuate a relay RA5. Relay RAS is thus actuated at the time when preliminary inking of the master plate or preliminary supply of ink thereto is finished, so that its normally open contact RAS-al shown in FIG. 5 is closed.

In FIG. 5, normally open contact RA5-a1 is shown as being connected between a positive direct current source E2 and one input terminal of an OR circuit ORl. Thus, when normally open contact RAS-al is closed, an output signal is produced by OR circuit ORl. On the other hand, a subtraction counter 52 which is set at a desired number of copy sheets to be printed from the master plate mounted on the master cylinder before preliminary inking is finished may be of any known type, such as the one which is manually operable.

The potential of the output of subtraction counter 52 is low when it is set, and this low potential is converted into a high potential by a NOT circuit NOTl and supplied to an AND circuit ANDl to keep the latter open.

Accordingly, the output signal of an OR circuit R1 is passed through AND circuit AND1, differentiated by a differentiation circuit D1 which is of a known type comprising a resistor R4 and a capacitor C3, and supplied to a setting input terminal S of a flip-flop FFl to set the flip-flop.

As shown in FIG. 3 and FIG. 6, a pulse generator PGl comprises a sector 53 connected to master cylinder 110 and disposed outwardly of a side plate 101 to which master cylinder 110, blanket cylinder 111 and impression cylinder 112 are connected through shafts. A light source or lamp 54 and a photoelectric transducer element 55 are supported by a supporter 56 while they are disposed opposite each other with respect to a portion of a path of movement of sector 53. Photoelectric transducer element 55 may be a cadmium sulfide element, phototransistor, photodiode, photoelectric tube or solar battery. The light incident on photoelectric transducer element 55 from lamp 54 is interrupted by sector 53 and the resistance value of the element increases for a predetermined time interval as master cylinder 110 makes one complete revolution. As shown in FIG. 4b, photoelectric transducer element 55 is connected through a resistor R5 between a positive direct current source E3 and ground. The junction between photoelectric transducer element 55 and resistor R5 is connected to a base of an NPN type transistor TRS whose emitter is grounded. A collector of transistor TRS is connected through a resistor R6 to positive direct current source E3 and has an output terminal 57. Thus, transistor TRS is turned on when the light from lamp 54 is incident on photoelectric lamp 55 and the resistance value of the latter is low and turned off when the light from lamp 54 is prevented by sector 53 from being incident on element 55 and the resistance value of the latter is high. As a result, one pulse is produced and taken out through output terminal 57 each time sector 53 makes one complete revolution together with master cylinder 110. This provides a count of each resolution of three cylinders.

Pulse generator PG2 comprises a hook member 155 which is coupled to a pressing mechanism adapted to bring impression cylinder 112 into pressing engagement with blanket cylinder 111 when a copy sheet 116 is fed between the two cylinders or when a copy sheet feed operation is performed. The pressing mechanism will be subsequently described in detail with reference to FIG. 7 to FIG. 16.

Hook. member 155 is released from locking engagement with a follower arm 160 by the pressing mechanism when a copy sheet feed operation is performed, arm 160 being supported by a shaft 161 connected to side plate 101 for pivotal motion with a light intercepting plate 165 as a unit and having a roller 181 connected thereto. Disposed outwardly of side plate 101 is a cam 1811 which is connected to blanket cylinder 111. A light source or lamp 166 and a photoelectric transducer element 58 inside window 59 are disposed opposite each other with respect to a portion of a path of movement of light intercepting plate 165 as shown in FIG. 3, lamp 166 and element 58 being supported by side plate 101. Thus, when no copy sheet 116 is fed between blanket cylinder 111 and impression cylinder 1 12 or when no copy sheet 116 is fed in spite of the fact that a copy sheet feed instruction has been given, follower arm 160 is locked by hook member 155, so that even if rotation of blanket cylinder 111 causes cam 180 to press against roller 181, follower arm and light intercepting plate move slightly and are restored to their original positions so as to permit the light from lamp 166 to be prevented by light intercepting plate 165 from being incident on photoelectric transducer element 58.

When copy sheet 116 is fed between blanket cylinder 111 and impression cylinder 112, follower arm 160 is released from locking engagement with hook member 155. This permits light intercepting plate 165 to be pivoted counter clockwise by the biasing force of a spring through a connecting rod 167, so that the light from lamp 166 is incident on photoelectric transducer element 58. Each time blanket cylinder 111 makes one complete revolution a major diameter portion of cam 1811 presses against roller 181 to cause follower arm 160 and light intercepting plate 165 to move in pivotal motion to intercept the light from lamp 166. Stated differently, the light from lamp 166 is incident on photoelectric transducer element 58 each time copy sheet 116 is fed between blanket cylinder 111 and impression cylinder 112.

Photoelectric transducer element 58 which may be a cadmium sulfide element, phototransistor, photodiode, solar battery or photoelectric tube, is connected between ground and a positive direct current source E4 through a resistor R7 as shown in FIG. 4c. Connected to the junction between photoelectric transducer element 58 and resistor R7 is a base of an NPN type transistor TR6 whose emitter is grounded. A collector of transistor TR6 is connected through a resistor R8 to positive direct current source E4 and has an output terminal 64). Thus, transistor TR6 is turned on when light is incident on photoelectric transducer element 58 and a pulse is taken out through the output terminal 60 of transistor TR6 each time feeding of copy sheet 116 between blanket cylinder 111 and impression cylinder 112 is finished. Sector 53 and cam are constructed and arranged such that the pulse thus produced by pulse generator PG2 is of smaller width than the pulse produced by pulse generator PGlI as aforementioned and the two pulses overlap each other when a copy sheet feed operation is performed.

Known means is provided (not shown) for bringing master cylinder 110 and blanket cylinder 111 into engagement with each other from the time when etching is finished but preliminary inking is not finished to the time when duplication of a predetermined number of copy sheets from the master plate on the master cylinder is finished but cleaning is not begun yet as shown in FIG. 3. Thus, an ink image of the master plate mounted on master cylinder 110is formed on blanket cylinder 111. Blanket cylinder 111 and impression cylinder 112 are brought into pressing engagement with each other by the aforementioned pressing mechanism during the time copy sheet 116 is fed between them.

In FIG. 5, flip-flop FF1 is set when preliminary inking is finished. Accordingly, an output signal is produced through an output terminal Q of flip-flop FFl and supplied through an OR circuit 0R2 to both a set input terminal S of a flip-flop FF2 and an AND circuit AND2, so that flip-flop FF2 is set. As a result, an output signal is produced through an output terminal Q of flip-flop FF2 an supplied through a NOT circuit NOT2 to a copy sheet feed solenoid S1. Since solenoid S1 is connected between a positive direct current source E5 and NOT circuit NOT2, it is energized when flip-flop F F2 is set.

Energization of solenoid S1 causes a copy sheet feed roller 61 to rotate and feed an uppermost copy sheet of a stack of copy sheets piled on a copy sheet feed tray 115 between blanket cylinder 111 and impression cylinder 112.

The copy sheet fed in this way is guided by guide plates 62 and 63 to move along a path between blanket cylinder 111 and impression cylinder 112. While the copy sheet is disposed between the two cylinders, the ink image of the master plate formed on blanket cylinder 111 is transferred to it so that it is converted into a printed copy sheet 64 which is removed from impression cylinder 112 by strip claws 65 and piled on a printed copy sheet tray 117.

Each time a copy sheet is fed between the two cylinders 111 and 112 a pulse is produced by pulse generator PGl. Each time blanket cylinder 111 makes one complete revolution a pulse is produced by pulse generator PG2. These pulses are supplied to AND circuit AND2, so that pulses are transmitted from AND circuit AND2 to subtraction counter 52 to subtract one from the number set each time a pulse is supplied to the latter.

Thus, one is subtracted from the number set by subtraction counter 52 each time one copy sheet is duplicated from the master plate mounted on master cylinder 110. Copy sheet feed solenoid S1 permits one copy sheet after another to be fed since a copy sheet feed instruction is given to the solenoid while flip-flop FF2 remains set. On the other hand, if the copy sheet feed device comprising solenoid S1 and copy sheet feed roller 61 is not actuated upon receipt of a copy sheet feed instruction, then production of pulses by pulse generator PG] is stopped. This results in no subtraction being effected by subtraction counter 52 because no pulses are transmitted from pulse generator PG2 to counter 52 through AND circuit AND2. Production of no pulses by pulse generator PGl results in no output signal of AND circuit AND2 being supplied to a NOT circuit NOT3, so that output signals of NOT circuit NOT3 and flip-flop FFl are supplied to AND circuit AND3. Thus, the pulse from pulse generator PG2 is taken out through an AND circuit AND3.

The pulse produced by pulse generator PG2 is supplied through an OR circuit R3 to a clear input terminal C of flip-flop FFl and through an OR circuit 0R4 to a clear input terminal C of flip-flop FFZ whereby flip-flops FFl and FF2 are cleared. As a result, the output of flip-flop FF2 is reduced in potential and the output of NOT circuit NOT2 is increased in potential so that copy sheet feed solenoid S1 is de-energized and feed of copy sheets is stopped.

However, pulses from AND circuit AND3 are supplied to a timer T1 which is adapted to operate for a predetermined small interval of time after it has received a supply of pulses. Timer T1 may, for example, be a monostable multivibrator. The output of timer T1 is supplied to relay RA2 through a NOT circuit NOT4, so that relay RA2 is actuated and its normally closed contact RA2-b is opened while relay RAl is deactuated and its normally open contact RAS-al is opened.

Upon lapse of the predetermined small time interval following the occurrence of misoperation of the copy sheet feed device, timer T1 ceases to produce an output signal and relay RA2 is de-actuated while relays RAl and RAS are actuated with a normally open circuit RAS-al being closed. Thus, AND circuit ANDl produces an output signal which is differentiated by differentiation circuit D1 so as to set flip-flop FFl by its rise pulse. As a result, flip-flop FFZ is set and copy sheet feed solenoid S1 is energized as aforementioned whereby feed of copy sheets is started again.

When a predetermined number of copy sheets have been printed from the master plate mounted on master cylinder 110 or when a number at which subtraction counter 52 is originally set becomes Zero as a result of subtraction and counter 52 is cleared, the potential of the output of counter 52 is increased. This turns off AND circuit AND2 while the output of subtraction counter 52 is differentiated by a known differentiation circuit D2 comprising a resistor R9 and a capacitor C4. A rise pulse of differentation circuit D2 is supplied to both a timer T2 and the clear input terminal C of flipflop FF2 through OR circuit 0R4. Timer T2 which operates for a predetermined time interval when a pulse is supplied to it may, for example, be a monostable multivibrator. The time interval during which it operates is set in accord with the cleaning time.

The output of timer T2 is supplied to a cleaning solenoid S2 after having its potential lowered by a NOT circuit NOT5. This energizes solenoid S2 and renders a cleaning device 66 shown in FIG. 3 operative. Cleaning device 66 comprises a lever 67 supported by a shaft connected to side plate 101 and adapted to be urged by the biasing force of a spring 68 to move toward its fixed end side to a position in which it abuts against a stopper 69 when solenoid S2 is de-energized. Device 66 also comprises a support plate 70 supported by a shaft connected to side plate 101 and adapted to be urged by the biasing force of a spring 71 to move to a position in which a pin 72 provided on support plate 70 is brought into abutting engagement with lever 67 when solenoid S2 is de-energized. Thus, a cleaning roller 73 supported by support plate 70 is moved away from blanket cylinder 111.

Upon energization of solenoid S2, lever 67 is moved in a direction opposite to the aforementioned direction by a movable shaft of solenoid S2 through a spring 74, with a result that support plate 70 is actuated to bring cleaning roller 76 into engagement with blanket cylinder 111. Thus, a cleaning solution 77 contained in a cleaning solution tank 76 is supplied to blanket cylinder 111 through an immersion roller and cleaning roller 73 which are supported by support plate 70 while being maintained in pressing engagement with each other. Thus, the ink image formed in blanket cylinder 111 is removed by cleaning.

If timer T2 is actuated, then the output of NOT gate NOTS has its potential reduced and differentiated by a differentiation circuit D3 comprising a capacitor C5 and a resistor R10. A rise pulse of differentiation circuit D3 sets a flip-flop F1 3. On the other hand, since the output subtraction counter 52 is supplied to the clear input terminal C of flip-flop FFl through OR circuit 0R3, flip-flop FFl is cleared when subtraction counter 52 is cleared.

If flip-flop FF3 is set, then its output is supplied together with the output of subtraction counter 52 to an AND circuit AND4 which products an output signal which is supplied through OR circuit 0R2 to the set input terminal of flip-flop FF2, so that flip-flop FF2 is set. This energizes solenoid S1 as aforementioned so that a copy sheet is fed and moves through the path between blanket cylinder 111 and impression cylinder 112. Copy sheets fed in this way perform the function of cleaning blanket cylinder 111 and impression cylinder 112, with a result that cleaning solution and ink adhere to the entire surfaces of copy sheers before the sheets are piled on a stack of printed copy sheets 64 on printed copy sheet tray 117. Adhesion of cleaning solution and ink to these copy sheets enables them to serve as copy sheet markers because they are readily discernible when the operator looks sideways at one side of the stack of printed copy sheets piled on the printed copy sheet tray.

Cleaning solution 77 need not be a colored solution which colors copy sheets to a degree such that they can be distinguished from ordinary printed copy sheets. An ordinary cleaning solution generally used in the trade will color copy sheets when mixed with ink so that the copy sheets used for cleaning can be readily distinguished from ordinary printed copy sheets.

On the other hand, the output of flip-flop FF3 is supplied together with the output pulses of pulse generators PGl and PG2 to an AND circuit ANDS which produces a pulse each time a copy sheet is fed when cleaning is carried out. This pulse is supplied to a counter 78 which counts the number of copy sheets intended to serve as copy sheet markers.

Counter 78 may, for example, be a ring counter which produces an output signal when a predetermined number set for copy sheets intended to serve as markers after being used for cleaning is counted. Thus, when a predetermined number of cleaning copy sheets are piled on the stack of printed copy sheets 64, counter 78 produces an output signal which is differentiated by a differentiation circuit D4. Differentiation circuit D4 produces an output signal which is supplied to a clear input terminal C of flip-flop FF3 to clear the same and at the same time to a clear input terminal C of flip-flop FF2 through OR circuit R4 to clear flip-flop FF2. This de-energizes solenoid S1, thereby stopping copy sheet feed.

On the other hand, timer T2 is de-actuated before copy sheet feed is stopped and solenoid S2 is deenergized, thereby stopping cleaning. The output of differentiation circuit D4 actuates a timer T3 for a small time interval, with an output signal of the latter being supplied to relay RY through a NOT circuit NOT6. This actuates relay RY and opens its normally closed contact RY-b, so that relays RA4 and RAS are de-actuated.

It start switch 33 is turned on following de-actuation of timer T3, the uppermost master plate of the stack of master plates on master plate feed tray 35 will be mounted on master cylinder 110 in the same manner as aforementioned for printing a predetermined number of copy sheets at which counter 52 is set. When misoperation of the copy sheet feed device occurs, depression of a switch 79 sets flip-flop FFl so as to carry out copy sheet feed as aforementioned because switch 79 is connected between positive direct current source E2 and OR circuit 0R1 through a resistor R11, in case the aforementioned device for restarting copy sheet feed fails to operate.

The relation between the parts shown in FIG. 2 and those shown in FIG. 5 will now be explained. Pulse generator 2 in FIG. 2 corresponds to pulse generator PGl in FIG. 5. AND circuit 3 to AND circuit ANDl, counter 1 to subtraction circuit 52, and judging circuit 4 to differentiation circuit D2. Timer circuit 10 in FIG. 2 corresponds to timer T2 in FIG. 5, and copy sheet feed solenoid 7 to solenoid S1. AND circuit 13 in FIG. 2 corresponds to AND circuit ANDS in FIG. 5, cleaning operation device 11 to solenoid S2, and copy sheet feed logic control circuit 5 to a circuit comprising flipflop FFl, differentiation circuit D1, AND circuit ANDl, OR circuit CR1 and relay RAS in FIG. 5. Copy sheet marker logic control circuit 12 in FIG. 2 corresponds to a circuit comprising flip-flop FF3, differentiation circuit D3 and AND circuit AND4 in FIG. 5 while copy sheet feed instruction circuit 6 in the former corresponds to a circuit comprising flip-flop F F2 and OR circuit OR2 and 0R4 in the latter. Copy sheet feed checking circuit 8 in FIG. 2 corresponds to a circuit comprising pulse generator PG2, NOt circuit NOT3, AND circuit AND3, Timer T1, NOT circuit NOT4 and relay RA2 in FIG. 5. It should be understood that some parts appearing in FIG. 2 are omitted, some parts are added and some parts appear in FIG. 5.

The mechanism for bringing blanket cylinder 111 and impression cylinder 112 into pressing engagement with each other will now be described with reference to FIG. 7 to FIG. 16.

FIG. 7 in which impression cylinder 112 is shown in a plan view further shows a follower plate 119 adjacent a right end of the cylinder, the plate 119 being pivotally supported as shown in FIG. 14 by a shaft 120 and supports a roller 121 adapted to cooperate with a cam 122 secured to an inner side of a right side plate 133 of the machine. Follower plate 119 has secured to its inner end a pin 123 which is loosely received in a slot 125 formed in a pivotal plate 124 secured to an outer end of a shaft 126 rotatably supported by opposite end plates of impression cylinder 112.

Secured to shaft 126 are sheet grip claws 127 which are urged by the biasing force of a compression spring 128 acting on pivotal plate 124 to be maintained in pressing engagement with a planar surface 129a of a marginal portion of a cutout 129 shown in FIG. 7. In FIG. 14, roller 121 is shown as riding on a major diameter portion of cam 122 and follower plate 119 is shown as having pivoted clockwise about shaft 120 to move pivotal plate 124 counter clockwise against the biasing force of spring 128, so that grip pawls 127 are in open positions.

Rotatably supported by the end plates of impression cylinder 1 12 as shaft 126 is another shaft 130 which has secured to its outer end a follower arm 131 supporting at its forward end portion a roller 132 which is adapted to cooperate with another cam 134 secured to an inner side of right side plate 133 shown in FIG. 7 and disposed outwardly of cam 122. Roller 132 is urged by the biasing force of a compression spring 135 mounted between follower arm 131 and a pin on impression cylinder 112 to be maintained in pressing engagement with cam 134.

Mounted on shaft 130 in side-by-side relationship are sheet push-out claws 136 which are disposed alternately with sheet grip claws 127 as shown in FIG. 7. Push-out claws 136 each have a forward end portion which is bent inwardly toward the periphery of impression cylinder 112 with a front end 136a being fitted in a recess 137 formed in planar surface 129a.

Secured to an upper surface of each grip claw 127 is a small thickness plate 138 having a bent forward end portion 138a which extends inwardly through an opening 139 formed in each grip claw 127. Bent forward portions 138a serve as stoppers against which a leading end edge of each copy sheet fed to be gripped by grip claws 127 abuts.

In FIG. 9, an eccentric shaft 140a is shown as being connected integrally to one end surface of a shaft 140 supporting impression cylinder 112 and journalled by a bearing secured to side plate 101. A follower plate 141 is firmly secured to a base of eccentric shaft 140a while a drive plate 142 is loosely mounted on an outer end of eccentric shaft 140a. A compression spring of relatively high resilience is mounted between a pin 143 connected to follower plate 141 and a pin 144 connected to drive plate 142, so that the two plates pull each other with bent portions 141a and 1420 thereof abutting against each other. Drive plate 144 is normally urged by the biasing force ofa compression spring 146 connected at one end to side plate 101 to pivot counter clockwise about eccentric shaft 140a. Pivotal movement of drive plate 142 caused by the biasing force of spring 146 is restricted by the abutting of a roller 147 against a fixed pin 148, roller 147 being connected to an arm of follower plate 141.

A hook lever 49 disposed upwardly rightwardly of follower plate 141 is pivotally supported by a shaft connected to side plate 101 and has at its forward end a hook 149a which is adapted to come into locking engagement with a forward bent portion 14212 of drive plate 142 extending upwardly therefrom. Hook lever 149 is normally urged by the biasing force of a spring (not shown) of relatively low resilience to pivot counter clockwise.

An arm 151 is secured to shaft 150 and has a bent portion 151a urged by the biasing force ofa spring 152 to press against hook lever 149. An inner arm 154 having a pin 153 connected to its forward end as shown in FIG. 13 is secured to an inner end of shaft 150 or an end inwardly of side plate 101. Thus, arm 151 and inner arm 154 are substantially integral with each other.

Disposed rightwardly of eccentric shaft 140a in FIG. 9 are the aforementioned hook member 155 and a short arm 156 which is arranged inwardly of member 155 in a superposing relationship, with member 155 and arm 156 being pivotally supported by a shaft 157. A compression spring 158 is mounted between hook member 155 and short arm 156 while a spring 159 is mounted between short arm 156 and drive plate 142.

The aforementioned follower arm 160 having a bent forward end portion maintained in locking engagement with a hook 155a of lock member 155 is pivotally supported by a shaft 161 which also supports for pivotal motion of lever 163 having a roller 162 mounted at its forward end, a lower end portion of lever 163 extending downwardly and disposed on the left side ofa roller 164 supported by drive plate 142 through a shaft.

The aforementioned light intercepting plate 165 extnding leftwardly from shaft 161 is substantially integral with follower arm 160 and has a forward end portion extending and disposed on the inner side ofa light receiving window on the outer side of which is disposed the aforementioned lamp 166. The aforementioned connecting rod 167 is connected at its upper end to light intercepting plate 165 and formed at its lower end portion with a slot 171 loosely receiving therein a pin connected to arm 169. Connecting rod 167 is urged to move downwardly by the biasing force of a compression spring 172 secured to side plate 101 at its lower end, and a compression spring 174 is mounted between pin 170 and a pin 173 connected to connecting rod 167, so that arm 169 is displaced downwardly with respect to connecting rod 167.

Arm 169 is secured to a shaft 175 rotatably supported by side plate 101 and having an inner arm 176 secured to an end thereof which extends inwardly of side plate 101. Vertical movement of connecting rod 167 causes movable side plates (not shown) to vibrate through arm 169 and inner arm 176 moving in pivotal motion so as to help arrange printed copy sheets in a stack with the front end edges being disposed in a vertical plane.

Following initiation of inking, a copy sheet feed instruction is automatically given after lapse of a predetermined time interval set beforehand by operating an inking time adjusting knob (not shown).

Upon receipt of a copy sheet feed instruction, the

copy sheet feed device starts feeding of copy sheets between blanket cylinder 111 and impression cylinder 112. A copy sheet fed in this way has its leading end edge thrust between open grip claws 127 shown in FIG. 14 and the planar surface 129a shown in FIG. 7. Counter-clockwise rotation of impression cylinder 112 results in a roller 121 of follower plate 119 being brought into engaagement with a minor diameter portion 122a of cam 122, and at the same time open claws 127 are closed to grip the leading end edge of the copy sheet (See FIG. 15). Further counter-clockwise rotation of impression cylinder 112 results in the roller 121 being brought into engagement with a major diameter portion 12217 of cam 122, and at the same time closed claws 127 are opened and release the leading end of the copy sheet. The roller 132 of follower arm 131 moves from a position in which it is in engagement with a major diameter portion 134a of cam 134 to a position in which it is in engagement with a minor diameter portion l34b thereof, simultaneously as roller 121 is brought into engagement with major diameter portion 122b as aforesaid. Thus, the released leading end of the copy sheet is pushed by push-out claws 136 out of impression cylinder 112 into the printed copy sheet tray.

The copy sheet gripped at its leading end edge by claws 127 has the ink image on blanket cylinder 111 transferred to it while it moves along the path between the two cylinders, so that it is printed from the master plate mounted on master cylinder 110.

The roller 132 which actuates push-out claws 136 passes through another minor diameter portion 134c before coming into engagement with the aforementioned minor diameter portion 134b thereof. If the copy sheet is properly gripped by claws 127, then pushout claws 136 are obstructed by the underside of the leading end portion of the copy sheet whereby roller 132 is kept from being brought into engagement with minor diameter portion 1346. However, when the copy sheet is not properly gripped, push-out claws 136 are free to move so that roller 132 is brought into engagement with minor diameter portion 1430 as shown in FIG. 16.

As shown in FIG. 16, an operation arm 177 is secured to an end of shaft 130 opposite to the end thereof to which follower arm 131 having roller 132 is secured. Operation arm 177 is adapted to pivot outwardly of impression cylinder 112 as shown in FIG. 16 when roller 132 is brought into engagement with minor diameter portion 134C or the copy sheet is not gripped by claws 127, so as to push the pin 153 of inner arm 154 outwardly. If pin 153 is pushed outwardly, then arm 151 which is substantially integral with inner arm 153 and disposed outwardly of side plate 101 pivots clockwise in FIG. 9. This causes hook member 149, which is connected to arm 151 through spring 152, to pivot in the same direction as arm 151.

Immediately before the leading end portion of the copy sheet gripped by claws 127 is introduced into its path between blanket cylinder 111 and impression cylinder 112, a major diameter portion 178a of a cam 178 adapted to rotate with impression cylinder 112 as a unit pushes roller 162 outwardly and causes lever 163 to pivot counter clockwise about shaft 161 as shown in FIG. 10. The lower end of lever 163 pushes roller 164 to thereby cause drive plate 142 to pivot clockwise about eccentric shaft 140a. Drive plate 142 thus moved in pivotal motion has its upper bent portion 142]; engaged by the hook 149a of hook lever 149 to be locked in a position shown in FIG. 10. When drive plate 142 pivots clockwise, follower plate 141 is pulled by the biasing force of spring 145 to pivot in the same direction, so that the eccentric shaft 140a to which follower plate 141 is secured simultaneously rotates and causes shaft 140 to rotate in the same direction, thereby bringing impression cylinder 112 into pressing engagement with blanket cylinder 111 while the copy sheet is held between the two cylinders.

In case the copy sheet is not gripped by grip claws 127, the bent portion 142 of drive plate 142 is not engaged by the hook 149a of hook lever 149, because hook lever 149 is pulled by arm 151 to pivot clockwise as aforementioned. That is, while pin 153 is maintained in its outer position by a forward end edge 177a of operation arm 177, drive plate 142 is caused to move in one reciprocating motion by the major diameter portion 1780 of cam 178.

The degree at which impression cylinder 112 bears against blanket cylinder 111 may vary depending on the amount of rotation of shaft 140 with respect to eccentric shaft 140a. In order to properly restrict the angle of clockwise pivotal movement of follower arm 141 secured to shaft 140, a pressing force adjusting cam 179 is mounted on side plate 101 as shown in FIG. 9. Cam 179 can have its rotation adjusted from outside the printing machine. By bringing roller 147 into abutting engagement with the periphery of cam 179, it is possible to adjust the angle of pivotal movement of follower arm 141 or the pressing force with which the impression cylinder bears against the blanket cylinder depending on the type of copy sheets handled and other circumstances.

The aforementioned cam 180 is shown in FIG. 9 as being arranged outwardly of cam 178. If cam 180 rotates clockwise with blanket cylinder 111, then a major diameter portion 180a thereof pushes slightly downwardly the forementioned roller 181 connected to follower arm 160 to loosen the locking engagement of follower arm 160 with lock member 155. However, follower arm 160 is not released from looking engagement with lock member 155 at this time because the latter is under the influence of spring 159, but follower arm 160 only moves slightly in pivotal motion each time the major diamete portion 180a of cam 180 is brought into abutting engagement with roller 181.

If drive plate 142 moves in pivotal motion into a position shown in FIG. 10, plate 142 moves at a side edge 142C thereof a pin 183 connected to arm 156. This causes arm 156 to pivot about shaft 157 whereby spring 158 is charged and hook member is urged by the biasing force of spring 158 to pivot clockwise about shaft 157. If roller 181 is pushed downwardly by the major diameter portion 1800 of cam 180 while spring 158 is charged as aforesaid, then hook member 155 is pulled by the biasing force of spring 158 to pivot clockwise about shaft 157, thereby releasing follower arm 160 from locking engagement with hook member 155. Thereafter, if the major diameter portion 180a of cam 180 passes by roller 181, then follower arm 160 is urged by the biasing force of compression spring 172 to pivot counter clockwise about shaft 161. This causes light intercepting plate to move downwardly relative to the light receiving window 59, so that the photoelectric transducer element 58 shown in FIG. 4c is actuated to produce a pulse.

Follower arm 160 is permitted to pivot only when drive plate 142 is in locking engagement with lock lever 149 of a copy sheet is gripped by the grip pawls on the impression cylinder. Follower arm 160 makes one reciprocating motion and a pulse is produced each time cam 180 makes one complete revolution while drive plate 142 is locked. The number of pulses produced in this way agress completely with the number of copy sheets to be printed from the master plate mounted on the master cylinder. Pivotal movement of light intercepting plate 165 causes the aforementioned movable side plates to vibrate through connecting rod 167,

arms

169, 175 and ajogger mechanism (not shown) whereby the front end edges of printed copy sheets piled in a stack can be arranged in a vertical plane.

The aforementioned pulse generator PGl may be provided with a switch for detecting feed of copy sheets to control the output of the direct current source in addition to switch 40 for detecting feed of a master plate. The device for producing pulses by means of a direct current source and a switch is known.

Each of the timers T1 to T3 may be a known time constant circuit comprising a resistor and a capacitor. Subtraction counter 52 may consist of an ordinary counter and another counter which is set at a predetermined number of copy sheets to be printed from one master plate, with a comparator circuit being provided to detect coinciding of the levels of the two counters and resetting the former counter.

What we claim is:

1. In a rotary offset printing machine of the type comprising:

a. a master cylinder on which a master plate is adapted to be mounted;

b. a master plate feed device for mounting a master plate on the master cylinder;

0. an etching device for applying an etching solution to the master plate mounted on the master cylinder;

d. an inking device for applying ink to the master plate mounted on the master cylinder;

e. a blanket cylinder on which an ink image of the master plate mounted on the master cylinder is adapted to be formed;

f. a copy sheet feed device for feeding copy sheets;

g. an impression cylinder for bringing each of the copy sheets fed into pressing engagement with the blanket cylinder to transfer the ink image from the blanket cylinder to the copy sheets to print the latter from the master plate mounted on the master cylinder;

b. means for piling printed copy sheets in a stack on a printed copy sheet tray;

i. a cleaning device for supplying a cleaning solution to the blanket cylinder for cleaning the same and removing the ink image therefrom each time duplication of a predetermined number of copy sheets from the master plate mounted on the master cylinder is completed; and

j. a start switch adapted to actuate said copy sheet feed device;

the improvement comprising a copy sheet distinguishing device comprising:

k. a first pulse generator for producing a signal pulse indicative of the feeding of a copy sheet by said copy sheet feed device onto said impression cylinder;

1. a second pulse generator for producing a signal pulse indicative of each revolution of said blanket cylinder;

m. a counter circuit for receiving and counting the number of pulses produced concurrently by said pulse generators and for producing an output signal when a predetermined number of pulses are counted;

n. a judging circuit for receiving the output signal from said counter circuit indicating when a predetermined number of pulses has been counted and for producing a plurality of output signals in response thereto, one of which signals deactivates said copy sheet feed device and one of which signals activates said cleaning device;

0. timer means adapted to operate for a predetermined time interval upon receipt of an output signal from saidjudging circuit and for thereafter providing a plurality of output signals, one of which deactivates said cleaning device;

p. a copy sheet marker logic control circuit responsive to an output signal from said timer means for producing signal pulses for actuating the copy sheet feed device to feed a predetermined number of additional copy sheets to the impression cylinder and the blanket cylinder to clean the latter;

q. means for then placing the copy sheets used for cleaning on the uppermost sheet of the stack of printed copy sheets on the printed copy sheet tray each time a predetermined number of copy sheets have been printed from the master plate mounted on the master cylinder whereby the copy sheets used for cleaning can serve as printed copy sheet markers; and

. counting means responsive to the signal pulse from said second pulse generator and said copy sheet marker logic control circuit for deactivating said copy sheet feed device after the predetermined number of additional copy sheets have been fed to the blanket cylinder.

2. A copy sheet distinguishing device as set forth in claim 1 wherein said timer comprises a monostable multivibrator.

3. A copy sheet distinguishing device as set forth in claim 1 wherein said timer comprises a time constant circuit.

4. A copy sheet distinguishing device as set forth in claim 1 wherein said first pulse generator comprises means for alternately permitting light from a light source to be incident on a photoelectric transducer element and intercepting said light by using a light intercepter coupled to means for bringing the impression cylinder into pressing engagement with the blanket cylinder each timer a copy sheet is fed so as to provide a pulse by varying the resistance of the photoelectric transducer element.

5. A copy sheet distinguishing device as set forth in claim 1 wherein said first pulse generator comprises a switch actuated by copy sheets fed by the copy sheet feed device, and a circuit adapted to produce pulses in response to said switch.

6. A copy sheet distinguishing device as set forth in claim 1 wherein said counter circuit comprises means adapted to be set at a predetermined number to be printed from one master plate and effect subtraction each time a pulse is produced by the first pulse generator.

7. A copy sheet distinguishing device as set forth in claim 1 wherein said copy sheet marker logic control circuit comprises a differentiation circuit, a flip-flop elememt, and an AND circuit.

8. A copy sheet distinguishing device as set forth in claim 1 wherein said counting means comprises an AND circuit, a counter, a differentiator circuit and an OR circuit.

9. A copy sheet distinguishing device as set forth in claim 1 further comprising a copy sheet feed checking circuit including said second pulse generator, two NOT circuits, two AND circuits, a timer and a relay.

10. A copy sheet distinguishing device as set forth in claim 1 wherein said second pulse generator comprises a photoelectric device and a sector element mounted for rotation with said master cylinder and interrupting said photoelectric device during a portion of each revolution.

11. In a rotary offset printing machine having a copy sheet feed device which is automatically controlled to feed copy sheets between a blanket cylinder and an impression cylinder, wherein the improvement comprises:

a. a first pulse generator means for producing a signal pulse indicative of the feeding of a copy sheet by said copy sheet feed device onto said impression cylinder;

b. a second pulse generator means for producing a signal pulse indicative of each revolution of said blanket cylinder;

0. a copy sheet feed control means for receiving the signal pulses from said first pulse generator means and producing a plurality of signal pulses in response thereof, one of which pulses activates said copy sheet feed device;

d. first AND gate means for receiving signal pulses from said second pulse generator and said copy sheet feed control means and producing a signal pulse when concurrently received;

e. counting means repsonsive to the signal pulses from said first AND gate means for counting the copy sheets fed by said copy sheet feed device;

f. completion judging means responsive to a signal from said counting means for producing a plurality of completion signals indicating when a predetermined number of copy sheets has been fed, one of which completion signals shuts off said copy sheet h. second AND gate means responsive to signal pulses from said second pulse generator means and said marker control means for producing a signal pulse when concurrently received; and

i. marker counter means responsive to signal pulses from said second AND gate means for deactivating said copy sheet feed device after the predetermined number of additional copy sheets have been fed to the blanket cylinder.

Claims

1. In a rotary offset printing machine of the type comprising: a. a master cylinder on which a master plate is adapted to be mounted; b. a master plate feed device for mounting a master plate on the master cylinder; c. an etching device for applying an etching solution to the master plate mounted on the master cylinder; d. an inking device for applying ink to the master plate mounted on the master cylinder; e. a blanket cylinder on which an ink image of the master plate mounted on the master cylinder is adapted to be formed; f. a copy sheet feed device for feeding copy sheets; g. an impression cylinder for bringing each of the copy sheets fed into pressing engagement with the blanket cylinder to transfer the ink image from the blanket cylinder to the copy sheets to print the latter from the master plate mounted on the master cylinder; h. means for piling printed copy sheets in a stack on a printed copy sheet tray; i. a cleaning device for supplying a cleaning solution to the blanket cylinder for cleaning the same and removing the ink image therefrom each time duplication of a predetermined number of copy sheets from the master plate mounted on the master cylinder is completed; and j. a start switch adapted to actuate said copy sheet feed device; the improvement comprising a copy sheet distinguishing device comprising: k. a first pulse generator for producing a signal pulse indicative of the feeding of a copy sheet by said copy sheet feed device onto said impression cylinder; l. a second pulse generator for producing a signal pulse indicative of each revolution of said blanket cylinder; m. a counter circuit for receiving and counting the number of pulses produced concurrently by said pulse generators and for producing an output signal when a predetermined number of pulses are counted; n. a judging circuit for receiving the output signal from said counter circuit indicating when a predetermined number of pulses has been counted and for producing a plurality of output signals in response thereto, one of which signals deactivates said copy sheet feed device and one of which signals activates said cleaning device; o. timer means adapted to operate for a predetermined time interval upon receipt of an output signal from said judging circuit and for thereafter providing a plurality of output signals, one of which deactivates said cleaning device; p. a copy sheet marker logic control circuit responsive to an output signal from said timer means for producing signal pulses for actuating the copy sheet feed device to feed a predetermined number of additional copy sheets to the impression cylinder and the blanket cylinder to clean the latter; q. means for then placing the copy sheets used for cleaning on the uppermost sheet of the stack of printed copy sheets on the printed copy sheet tray each time a predetermined number of copy sheets have been printed from the master plate mounted on the master cylinder whereby the copy sheets used for cleaning can serve as printed copy sheet markers; and r. counting means responsive to the signal pulse from said second pulse generator and said copy sheet marker logic control circuit for deactivating said copy sheet feed device after the predetermined number of additional copy sheets have been fed to the blanket cylinder.

11. In a rotary offset printing machine having a copy sheet feed device which is automatically controlled to feed copy sheets between a blanket cylinder and an impression cylinder, wherein the improvement comprises: a. a first pulse generator means for producing a signal pulse indicative of the feeding of a copy sheet by said copy sheet feed device onto said impression cylinder; b. a second pulse generator means for producing a signal pulse indicative of each revolution of said blanket cylinder; c. a copy sheet feed control means for receiving the signal pulses from said first pulse generator means and producing a plurality of signal pulses in response thereof, one of which pulses activates said copy sheet feed device; d. first AND gate means for receiving signal pulses from said second pulse generator and said copy sheet feed control means and producing a signal pulse when concurrently received; e. counting means repsonsive to the signal pulses from said first AND gate means for counting the copy sheets fed by said copy sheet feed device; f. completion judging means responsive to a signal from said counting means for producing a plurality of completion signals indicating when a predetermined number of copy sheets has been fed, one of which complEtion signals shuts off said copy sheet feed control means closing said first AND gate means and deactivating said copy sheet feed device; g. marker control means responsive to a completion signal from said completion judging means for producing a plurality of signal pulses, one of which activates said copy sheet feed device to feed a predetermined number of additional copy sheets to said blanket cylinder while said counting means is stopped; h. second AND gate means responsive to signal pulses from said second pulse generator means and said marker control means for producing a signal pulse when concurrently received; and i. marker counter means responsive to signal pulses from said second AND gate means for deactivating said copy sheet feed device after the predetermined number of additional copy sheets have been fed to the blanket cylinder.