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Publication numberUS3869202 A
Publication typeGrant
Publication dateMar 4, 1975
Filing dateDec 7, 1973
Priority dateDec 29, 1972
Publication numberUS 3869202 A, US 3869202A, US-A-3869202, US3869202 A, US3869202A
InventorsYasuhiro Tabata, Takeshi Ukai
Original AssigneeRicoh Kk
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electrophotographic copying machine
US 3869202 A
Abstract
An electrophotographic copying machine is provided including an original receptacle having a first and a second surface for placing a pair of originals thereon. The machine also includes a charger, an exposure unit, a developing unit and a transfer unit which are arranged around a rotatable body of photosensitive material in a conventional manner. The transfer unit transfers a developed image on the body onto a transfer sheet. The machine also includes a fixing unit in which the transferred image on the transfer sheet is fixed and in which the transfer sheet is momentarily held subsequent to the copying of the original placed on the first surface. Thereafter, the original receptacle is moved to present another original on the second surface into a predetermined exposure position, and the copying operation is repeated for the second original. During the second copying operation, the transfer unit is held inoperative, and the transfer sheet which has been held in the fixing unit is moved into operative association with the developed image on the rotating body for transferring the latter onto the opposite surface of the transfer sheet.
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Description  (OCR text may contain errors)

United Sttes tent [191 Tabata et a1,

[ Mar. 4, 1975 ELECTROPHOTOGRAIPHKC COPYING MACHINE [75] lnventors: Yasuhiro Tabata, Yokohama;

Takeshi Ukai, Tokyo, both of Japan [73] Assignee: Ricoh Co., Ltd, Tokyo, Japan [22] Filed: Dec. 7 1973 [21] Appl. No: 422,788

[30] Foreign Application Priority Data Primary E.\'aminer-Richard A. Wintercorn Attorney, Agent, or Firm-Cooper, Dunham, Clark, Griffin & Moran 7] ABSTRACT An electrophotographic copying machine is provided including an original receptacle having a first and a second surface for placing a pair of originals thereon. The machine also includes a charger, an exposure unit, a developing unit and a transfer unit which are arranged around a rotatable body of photosensitive material in a conventional manner. The transfer unit transfers a developed image on the body onto a transfer sheet. The machine also includes a fixing unit in which the transferred image on the transfer sheet is fixed and in which the transfer sheet is momentarily held subsequent to the copying of the original placed on the first surface. Thereafter, the original receptacle is moved to present another original on the second surface into a predetermined exposure position, and the copying operation is repeated for the second original. During the second copying operation, the transfer unit is held inoperative, and the transfer sheet which has been held in the fixing unit is moved into operative association with the developed image on the rotating body for transferring the latter onto the opposite surface of the transfer sheet.

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ELECTROPHOTOGRAPHIC COPYING MACHINE BACKGROUND OF THE INVENTION The invention relates to an electrophotographic copying machine which permits an automatic copying on the opposite surfaces of a transfer sheet.

The prior art electrophotographic copying machines are adapted to provide a copy on only one surface of a copy sheet. While proposals have been made to provide an automatic copying onto the both surfaces of a transfer sheet, technical difficulties involved preclude their practical use. When producing copies on both surfaces of asingle transfer sheet, it is desirable that the copies QnPQt a i ses b eprodg dseesaw? scale, particularly when a pair of opposing pages of a book are to be copied.

It is also noted that when copying a plurality of originals consecutively with a conventional electrophotographic copying machine, each original must be set in place on and removed from the original receptacle before and. af n ashsr si rsrandittekss a relativi/ longperiod of time for placing and removing a plurality of originals onto and from the single exposure position in a successive manner. I

SUMMARY OF THE INVENTION It is an object of the invention to provide an electrophotographic copying machine which permits an automatic copying operation onto the both surfacesof a single transfer sheet.

It is another object of the invention to provide an electrophotographic copying machine which reduces the time required for copying a plurality of originals consecutively.

In accordance with the invention, there is provided an electrophotographic copying machine including an original receptacle having a first and a second surface for placing a pair of originals thereon. In response to a copy instruction, a copying operation is initiated to provide a copy of the original placed on the first surfaces of the transfer sheet can be obtained on th esarne transfer sheet, followed by a second copying operation which provides a copy of the original on the second surface of the original receptacle onto the opposite surface of the same transfer sheet. By controlling the stroke through which the original receptacle is moved to have the original on its first and second surfaces to be copied successively, the copies of the opposite suraces of the fi l i fl heet nbs bta n at i same changing operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing one embodiment of the electrophotographic copying machine according to the invention;

FIG. 2 is a schematic view illustrating part of the exposure unit used in the embodiment of FIG. I; and

FIGS. 3 and 4 are circuit diagrams showing the electrical system incorporated in the embodiment of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, the electrophotographic copying machine includes a body of photosensitive material 11 which is shown in the form of a rotatable drum. As is conventional, a charger 12, an exposure unit 13, a developing unit 14, a transfer unit 15, a separator l6 and a cleaner 19 are arranged successively around the periphery of the drum 11 along the direction in which the drum 11 rotates. In accordance with the invention, another transfer unit 17 and another separator 18 are disposed around the periphery of the drum 11 in the space between the first mentioned separator 16 and the cleaner 19. As shown in FIG. 2, the exposure unit 13 includes a transparent original receptacle 20 having a first surface B and a second surface C located on the opposite sides of a central reference line A. The exposure unit also includes a movable scanning system comprising a lamp 21 and an optical system (not shown) which provides a slitwise exposure of an original placed on one of the first andsecond surfaces and projects its image onto the photosensitive body 11 while the scanning system moves from a reference line D to a preset line E, the latter being determined by a copy size establishing member 22. A pair of switches SW9 and SW11 are disposed in alignment with the reference line D, while another pair of switches SW10 and SW12 are located on the preset line E by being integrally connected with the member 22. Normally, the original receptacle 20 assumes a home position shown in which the reference lines A and D are aligned with each other, and an operating member 23 is secured to the underside of the original receptacle 20 in alignment with the reference line A for operating the switches SW9 and SW10. Another operating member 24 for operating the switches SW11 and SW12 is integrally s ecured to the scanning system, and is normally located on the reference line D.

The transfer unit 15 comprises a transfer roller 25 which is driven for rotation with the same peripheral speed as the photosensitive body 11, but in the reverse direction. The transfer roller 25 is pivotally mounted on one end of an L-shaped lever 26 which is pivotally mounted at its bend, with its other end being connected through a spring 27 with the plunger of a solenoid SOL2 and also connected through a return spring 28 with a stationary point. When the solenoid SOL2 is not energized, the transfer roller 25 assumes a position in which the lever 26 abuts against a stop 29 under the action of the return spring 28, thus being removed from the photosensitive body 11. However, when the solenoid SOL2 is energized, its plunger is retracted to cause a counter-clockwise rotation of the lever 26 through the spring 28, whereby the transfer roller is moved into abutment against the photosensitive body 11. The transfer unit 17 is similarly constructed and comprises a transfer roller 30 which is adapted to be moved into abutment against the drum 11 when a solenoid SOLl (See FIG. 4) is energized. It should be noted that the transfer may take place by means of a charger instead of a transfer roller. A paper feeder 31 supplies a sheet of transfer paper 32 through the nip defined between a pair of feed rollers 33 and 34 into the space between the transfer roller 25 and the drum 11. The roller 33 is positively driven for rotation at a given speed, while the roller 34 is pivotally mounted on one end of an L- shaped lever 35 which is pivotally mounted at its bend and which has its other end connected with the plunger of a solenoid SOL4 through a spring 36 and also connected with a stationary point through a spring 37. When the solenoid SOL4 is not energized, the lever 35 rotates clockwise to a position in which it abuts against a stop 38 under the action of the return spring 37, whereby the roller 34 is removed from the roller 33. When the solenoid SOL4'is energized, its plunger is retracted to cause a counterclockwise rotation of the lever 35, whereby the roller 34 is moved into abutment against the roller 33. A transfer sheet is fed sheet by sheet into the nip between the rollers 33 and 34, and

is fed into the space between the drum 11 and the transfer roller 25 by the pair of rollers 33 and 34 when the latter are in abutment with each other.

The separator 16 comprises a separating pawl which detaches a transfer sheet from the drum 11, the detached transfer sheet being guided between a pair of guide plates 39 and 40 as well as under a guide member 41 onto an endless belt 42 which extends around a pair of rollers 43 and 44. The belt 42 is adapted to be driven in the forward or reverse direction under the control of a pair of clutches CL2 and CL3. A fixing unit 45 is disposed above the endless belt 42 and fixes the image on the transfer sheet which is carried on the belt 42 when the latter is driven in the forward direction. A switch SW6 is located along the path through which the transfer sheet is conveyed. Beyond the roller 44, as considered in the direction in which the transfer sheet is conveyed along the belt during its forward run, there is provided a pair of normally rotating rollers 57 and 58, and a switch SW7 is disposed beyond these rollers. It is to be noted that both of the switches SW6 and SW7 are operative when a copy is to be made on only one surface of the transfer sheet, but that only the switch SW6 is operative when copies are made the both surfaces of the transfer sheeti ln accordance with the invention, another endless belt 46 is provided which extends around a pair of rollers 47 and 48 and which is driven under the control of a clutch CL3, in a direction to convey the transfer sheet which has been carried thereonto over the guide member 41 from the belt 42 being driven in the reverse direction, into the space between the drum 11 and the transfer roller 30. A switch SW is disposed along the path of travel of the transfer sheet on the endless belt 46, to be operated by the transfer sheet. The separator 18 comprises a separating pawl similarly constructed as that used in the separator 16, and the transfer sheet detached from the drum by the separating pawl 18 is guided between a pair of guide plates 49 and 50 onto an endless belt 51 and thence to an outlet. The endless belt 51 extends around a pair of rollers 52 and 53, and a fixing unit 54 is disposed above the belt 51. A switch SW8 is disposed between the fixing unit 54 and the outlet to be operated by the transfer sheet. A cam 55 is connected with the drum 11 through a clutch CH and a gearing 56, and is surrounded by switches SW1, SW2, SW3 and SW4 which are spaced apart circumferentially of the cam. Referring to FIG. 3, there are shown a pair of terminals B1 and B2 which are adapted to be connected with an ac. source, the terminal B1 being connected through a fuse Fand a master switch MS with a line B3 and the terminal B2 being connected with a line B4. Various solenoids, clutches and drive motors as well as related control relays are connected across the pair of linesB3 and B4. When the master switch MS is closed, the fixing units 45 and 54 and a motor M1 are energized, the motor M1 activating the developing unit 14 and the cleaner 19 and also driving the drum 11 for rotation. Also a timer T1 is operated.

Under this condition, when a single surface print switch SSW is closed, a relay coil RA2 is energized to close its normally open contact RA2-al which selfholds this relay. Also its normally open contacts RA2- a2 and RA2-a3 are closed while its normally closed contacts RA2-bl, RA2-b2 and RA2-b3 are opened. The closure of the normally open contact RA2-a2 re sults in the energization of a relay coil RAl, whereby its normally open contact RAl-al is closed to self-hold this relay. Also normally open contacts RAl-a2, RAla3, RA1-a4 and RAl-aS are closed. The closure of the normally open contact RA1-a2 results in the energization of a relay coil RA4, whereby its normally open contact RA4-a1 is closed to self-hold this relay and also its normally open contacts RA4-a2 and RA4-a3 are closed. The closure of the normally open contact RA4- a3 energizes the solenoids SOLZ and SOL3, whereby the transfer roller 25 is moved into abutment against the drum 11 and the separator pawl 16 is also moved into abutment against the drum. The closure of the normally open contact RA1-a4 energizes the clutch CL2 to drive the endlessbelt 42 in the forward direction, while the charger 12 is energized by the closure of the normally open contact RAl-aS to effect charging of the photosensitive body 11. The closure of the normally open contact RAl-a3 energizes the clutch CLl, wherby the cam 55 is driven for rotation. As the cam 55 starts to rotate from its home position, the switch SW1 is closed. When the switch SW2 is closed by the cam 55 subsequently, a relay coil RA6 is energized to close its normally open contact RA6-a1 for self-holding this relay and to close its normally open contacts RA6- a2 and RA6-a3 while opening its normally closed contact RA6-b. The closure of the normally open contact RA6-a2 causes an illumination of the lamp 21, and the closure of the normally open contact RA6-a3 causes a motor M3 to rotate in the forward direction, whsrqbiths 9. 22! aas hs raqal te ar m ved in the direction indicated by an arrow in FIG. 2 to provide an exposure of an original placed on the first surface B of the original receptacle 20 and the projection of its image onto the photosensitive body 11 to form an electrostatic latent image thereon. The latent image formed is developedwith toner at the developing unit 14. When the lamp 21 and the optical system start to move, the operating member 24 also starts to move, thereby closing the switch SW11. When the scanning system comprising the lamp 21 and the optical system has moved to an extent such that the exposure of the original has proceeded to the preset line E established by the copy size establishing member 22, the operating member 24 operates the switch SW12, whereby the relay coil RA6 is deenergized. As a consequence, the lamp 21 is extinguished, and the motor M3 is driven in the reverse direction, whereby the scanning system returns and the switch SW12 resumes its original position. A switch SW13 is adapted to be closed when originals on the first and second surfaces B and C of the original receptacle 20 are to be copied alternately on one surface of separate transfer sheets. When the switch SW13 is closed, a relay coil RA7 becomes energized as the switch SW12 is operated, and its normally open contact RA7-a1 is closed to self-hold this realy. Also its normally open contact RA7-a2 is closed while its normally closed contact RA7-b is opened. The closure of the normally open contact RA7-a2 causes a motor M4 to rotate in the forward direction, whereby the original receptacle 20 is moved in the direction indicated by an arrow in P16. 2. As the original receptacle 20 moves, the operating member 23 moves therewith, thereby closing the switch SW9. When the original receptacle 20 has moved to an extent such that the reference line A thereon has moved into alignment with the preset line E, the operating member 23 operates the switch SW10 to interrupt the energization of the motor M4, whereby the receptacle comes to a stop. When the scanning system has returned to its home position, the operating member 24 opens the switch SW11, whereby the operation of the motor M3 is interrupted and the scanning system comes to a stop. Subsequently when the switch SW3 is closed by the cam 55, the solenoid SOL4 is energized, whereby a transfer sheet 32 is fed into the space between the transfer roller and the drum 11 for allowing a transfer of the image on the photosensitive bodyll onto the transfer sheet 32. The transfer sheet having an image transferred thereto is detached from the drum 11 by the separator pawl 16 and is guided between the guide plates 39 and 40 as well as guide member 41 onto the endless belt 42 to be carried thereon through the fixing unit 45 for the purpose of fixing the toner image. After the transfer sheet has been fixed by the fixing unit 45, the switch SW6 is operated, whereby the relay coil RAl is deenergized to deactivate the charger 12 and also the relay coil RA3 is energized. The energization of the relay coil RA3 closes its normally open contact RA3-a1 to self-hold this relay, and also closes its normally open contact RA3-a2 to feed power to a timer T. Also its normally closed contacts RA3-b1 and RA3-b2 are opened. The opening of the normally open contact RA3-b2 deenergizes the solenoids SOL2 and SOL3, whereby the transfer roller 25 and the separator pawl 16 are moved away from the drum 11. The transfer sheet which is fixed in the fixing unit 45 is further conveyed on the belt to be discharged through an outlet, and in the course of such movement, operates the switch SW7, whereby the relay coils RA2 and RA4 are deenergized and the timer T is also deenergized to reset the electrical system. As a result, the transfer sheet is discharged with a copy formed only on one of its surfaces. It will be appreciated that the size of the copy obtained can be varied by moving the member 22. When the switch SW13 is closed, the switch SSW is closed for providing an exposure for the next copying operation by the time the timer Tl times out after a time period on the order of 20 seconds subsequent to the turning off of the timer T1 by the switch SW7. In this manner, an original placed on the second surface C of the original receptacle 20 is copied in a similar manner. When the timer T1 is turned on to reset its normally open contact Tl-a, the relay coil RA7 is deenergized, whereby the motor M4 is driven in the reverse direction to return the original receptacle 20 to its original position, whereupon the operating member 23 opens the switch SW9 to interrupt the operation of the motor M4, and the original receptacle 20 comes to a stop.

Therefore, during the time the switch SW13 is closed, the originals placed on the first and second surfaces B and C of the original receptacle 20 are alternately copied onto one surface of separate transfer sheets. When the switch SW13 is not closed, only the original placed on the first surface B of the original receptacle 20 is copied.

When the double surface print switch DWS is closed under the condition the master switch MS is closed, the relay coil RAl is energized to close its normally open contact RAl-a l which self-holds this rela y, and also closes its normally open contacts RA2-a2 to RA2-a5. The closure of the normally open contact RA1-a2 energizes the relay coil RA4, which closes its normally open contact RA4-a1 to self-hold this relay and also closes its normally open contacts RA4-a2 and RA4-a3. The closure of the normally open contact RA4-a3 energizes the solenoids SOL2 and SOL3, whereby the transfer roller 25 is moved into abutment against the drum 11 and the separator pawl 16 is also moved into abutment against the drum 11. The closure of the normally open contact RA1-a4 energizes the clutch CL2, whereby the endless belt 42 is driven in the forward direction. The closure of the normally open contact RAl-aS activates the charger 12 for charging the photosensitive body 11, and the closure of the normally open contact RAl-a3 energizes the clutch CLl to drive the cam 55 for rotation. The switch SW1 is closed when the cam 55 rotates from its home position. Subsequently when the switch SW2 is closed by the cam 55, the relay coil RA6 is energized to close its normally open contact RA6-al for self-holding this relay, and to close its normally open contacts RA6-a2 and RA6-a3 while opening its normally closed contact RA6-b. The closure of the normally open contact RA6-a2 illuminates the lamp 21, and the closure of the normally open contact RA6-a3 causes the motor M3 to rotate in the forward direction, whereby the scanning system comprising the lamp 21 and the optical system moves so as to provide an exposure of the original placed on the first surface B of the original receptacle 20 and projection of its image onto the photosensitive body 11 to form an electrostatic latent image thereon. This electrostatic latent image is developed with toner at the developing unit 14. As the scanning system starts to move, the operating member 24 also moves simultaneously to close the switch SW11. When the scanning system has moved to such an extent that the exposure of the original has proceeded to the preset line E, the operating member 24 operates the switch SW12, whereby the relay coil RA6 is deenergized. Thus, the lamp 21 is extinguished and the motor M3 is caused to rotate in the reverse direction, returning the scanning system to its original position and resettingthe switch SW12. When the scanning system is returned to its original home position, the operating member 24 opens the switch SW11, thereby interrupting the operation of the motor M3 and bringing the scanning system to a stop. When the switch SW12 is operated by the operating member 24, the relay coil RA7 is energized, whereby its normally open contact RA7-a1 is closed to self-hold this relay. Also its normally open contact RA7-a2 is closed while its normally closed contact RA7-b is opened. The closure of the normally open contact RA7-a2 causes the motor M4 to rotate in the forward direction, whereby the original receptacle 20 is driven in the direction indicated by the arrow. As the receptacle 20 moves, the operating member 23 moves simultaneously, whereby the switch SW9 is closed. When the original receptacle 20 has moved to bring the reference line A thereon into alignment with the present line E, the operating member 23 operates the switch SW10, interrupting the operation of the motor M4 and bringing the receptacle 20 to a stop. Subsequently when the switch SW3 is operated by the cam 55, the solenoid SOL4 is energized to feed a transfer sheet 32 into the space between the photosensitive body 11 and the transfer roller 2S'for transferring a toner image from the photosensitive body 11 onto the transfer sheet 32. The transfer sheet having the toner image transferred thereto is detached from the drum by the separator pawl 16, and is guided by the guide plates 39 and 40 as well as guide member 41 onto the endless belt 42. During the time the transfer sheet is carried on the belt 42, the toner image thereon is fixed by the fixing unit 45. As the transfer sheet operates the switch SW6, the relay coil RA] is deenergized to deactivate the charger 12 and the clutch CL2 is deenergized to stop the endless belt 42. The actuation of the switch SW6 is also effective to energize the relay coil RA3, whereby its normally open contact RA3-al is closed for self-holding this relay. Also its normally open contact RA3-a2 is closed to feed power to the timer T, and its normally closed contacts RA3-bl and RA3-b2 are opened. The opening of the normally closed contact RA3-b2 deenergizes the solenoids 501.2 and SOL3, whereby both the transfer roller 25 and the separator pawl 16 are moved away from the photosensitive body 11. The cam 55 continues to rotate past the switch SW4. At an established period of time since the supply of power thereto, the timer T becomes operative to close its normally open contacts T-al, T-a2, T-a3, T-a4 and T-aS and to open its normally closed contact T-b. The closure of the normally open contact T-a2 energizes the solenoid SOLl, whereby the transfer roller 30 is movedinto abutment against the photosensitive body 11, and the closure of the normally open contact T-a3 permits the clutch CLI to be energized continuedly, thereby causing the cam 55 to continue to rotate. The closure of the normally open contact T-a4 energizes the clutch CL3 to drive the endless belts 42 and 46 in the reverse direction, whereby the transfer sheet which has been held on the endless belt 42 is conveyed toward the space between the drum 11 and the transfer roller 30. The closure of the normally open contact T-a5 activates the charger 12, thus charging the photosensitive body 11 again. The switch SW6 is reset when the transfer sheet has moved past it, and as the switch SW5 is operated by the transfer sheet moving in the reverse direction, the clutch CL3 is deenergized to interrupt the movement of the endless belts 42 and 46. When the switch SW2 is operated by the cam 55, the relay coil RA6 is energized, whereby its normally open contact RA6-a1 is closed to selfhold this relay. Also its normally open contacts RA6-a2 and RA6-a3 are closed while its normally closed contact RA6-b is opened. The closure of the normally open contact RA6-a2 is effective to illuminate the lamp 21, and the closure of the normally open contact RA6-a3 causes the motor M3 to rotate in the forward direction, moving the scanning system in the direction indicated by the arrow and thus providing an exposure of an original placed on the second surface C of the receptacle 20 and projecting its image onto the photosensitive body 11 to form an electrostatic latent image thereon. The latent image form is developed with toner at the developing unit 14. As the scanning system starts to move, the operating member 24 also starts to move simultaneously, closing the switch SW11. When the scanning system has moved to an extent such that the exposure of the original has proceeded to the preset line E, the operating member 24 operates the switch SW12 to deenergize the relay coil RA6. As a consequence, the lamp 21 is extinguished and the motor M3 is caused to rotate in the reverse direction, returning the scanning system and resetting the switch SW12. When the scanning system has returned to its home position, the operating member 24 opens the switch SW11, whereby the operation of the motor M3 is interrupted and the scanning system comes to a stop. Subsequently, when the switch SW3 is closed by the cam 55, the solenoid SOL4 remains without energization, and no transfer sheet is supplied. When the switch SW4 is operated by the cam subsequently, the relay coil RAS is energized, whereby its normally open contact RAS-al is closed to self-hold this relay and also its normally open contact RA5-a2 is closed. The closure of the normally open contact RA5-a2 energizes the clutch CL3, whereby the endless belts 42 and 46 resume their movement in the reverse direction. As a result, the transfer sheet which has been on the endless belt 46 is fed into the space between the photosensitive body 11 and the transfer roller 30 for transferring a toner image from the photosensitive body 11 onto the transfer sheet. This resultsin the transfer sheet having copies formed on its both surfaces. This transfer sheet is detached from the photosensitive body 11 by the separator pawl 18, guided between the guide plates 49 and 50 onto the endless belt 51, and the toner image thereon is fixed during the time the transfer sheet is conveyed on the'endless belt 51. After fixing, the transfer sheet is discharged through an outlet, and in the course of discharge, the switch SW8 is operated by the transfer sheet. When the switch SW8 is operated, the relay coils RA3, RA4, RAS, RA7 and the timer T as well as the solenoid SOL] are deenergized, whereby the transfer roller 30 is moved away from the drum l1 and the clutch CL3 is deenergized to interrupt the operation of the endless belts 42 and 46. The motor M4 is caused to rotate in the reverse direction, returning the original receptacle 20 to its home position. When the original receptacle 20 has returned to its home position, the operating member 23 opens the switch SW8, whereby the operation of the motor M4 is interrupted and the original receptacle 20 comes to a stop. The transfer sheet discharged through the outlet has the image of the originals placed on the first and second surfaces B and C of the original receptacle 20 copied on both its surfaces with an equal size, which is arbitrarily established by the copy size establishing member 22.

The electrophotographic copying machine described above can be used in combination with a known device which provides an instruction for copying any desired number of sheets in succession. For example, the number of copies to be obtained can be set in a counter mechanism by manual operation, and the counter mechanism may be counted down each time a copy is made on one surface of a transfer sheet so as to maintain the switch DSB closed unless and until the count in the counter mechanism is zero. With this arrangement, it is only necessary to close the switch DSB only once and subsequently the desribed copying operation equal to the count manually set in the counter mechanism. In this instance, during the time one of the originals on either the first or second surface of the original receptacle is-being exposed, the other original can be changed, thus allowing a plurality of originals to be copied continuously.

Wll laime V 1. An electrophotographic copying machine including a rotatable body of photosensitive material; an orig inal receptacle for placing an original thereon; and a charger, an exposure unit, a developing unit and a transfer unit arranged in sequence around the periphery of the rotatable body along the direction in which. the body is rotated, said charger being efftitive to charge the body when it is desired to obtain a copy, said exposure unit being effective to provide an exposure of an original placed on a predetermined surface of the original receptacle and projecting an image thereof onto the body to form an electrostatic latent image thereon, the developing unit being effective to develop the latent image with a toner, the transfer unit effecting a transfer of the developed toner image on the body onto one surface of a transfer sheet supplied thereto; and a fixing unit for fixing the transferred image on the transfer sheet; wherein the improvement comprises: said original receptacle a first and a second surface said original receptacle having a first and a second 10 surface for placing a pair of originals thereon and being movable so as to selectively bring the first or second surface into a predetermined position. and a second transfer unit arranged around the periphery of the body at a position beyond the developing unit as viewed in the direction of rotation of the body, the machine being adapted to effect a two cycle copying operation wherein in the first cycle, an original placed on the first surface is copied on a first surface of a transfer sheet, which sheet is conveyed to and retained in said fixing unit until during the second cycle, a developed image of an original placed on the second surface of the original receptacle is formed on the body, whereupon the transfer sheet retained in the fixing unit is supplied to the second transfer unit for bringing its second surface into operative association with the developed iaaaa athelzqyaw ,7 V r. ,7 V. c

2. An electrophotographic copying machine according to claim 1, further including means for presetting a number of times the two cycle copying operation is to be repeated continuously 3. An electrophotographic copying machine according to claim 1, further including means for controlling the operation of the machine to terminate it after a single copying operation.

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Classifications
U.S. Classification399/401, 399/82, 355/23, 271/3.19, 271/65
International ClassificationG03G15/23, G03G15/00
Cooperative ClassificationG03G15/234
European ClassificationG03G15/23B1R