US3848991A

US3848991A - Electrophotographic copying apparatus

Info

Publication number: US3848991A
Application number: US00405907A
Authority: US
Inventors: K Zeuthen
Original assignee: Rexomi AS
Current assignee: Rexomi AS
Priority date: 1972-09-13
Filing date: 1973-10-12
Publication date: 1974-11-19
Anticipated expiration: 1991-11-19

Abstract

An electrophotographic copying apparatus in which an original and a copy sheet are advanced during reproduction in a downwards direction along mutually spaced, substantially vertical conveying paths, start positions for the advancement of the original and the copy sheet being defined by stop members inserted into the respective conveying paths, which stop members are retracted from their inserted positions in a timed sequence with the start of a main driving system, the advancement of a copy sheet from a sheet supply to the copy sheet conveying path and the operation of a corona charging unit and an exposure lamp, by programming means including a single disc-shaped timing member which is mounted for rotation in the apparatus and is coupled with the main driving system, said timing member actuating all of the control functions in a correctly timed sequence during a single revolution.

Description

Zeuthen [451 Nov. 19, 1974 ELECTROPHOTOGRAPHIC COPYING APPARATUS Karl Gustav Zeuthen, Gentofte, Denmark [75] Inventor:

[73] Assignee: Rexomi A/S, Copenhagen, Denmark [22] Filed: Oct. 12, 1973 [21] Appl. No.: 405,907

[30] Foreign Application Priority Data Oct. 17, 1972 Denmark 5123/72 [52] U.S. Cl. 355/14, 355/3 R [51] Int. Cl 603g 15/00 [58] Field of Search 355/3 R, 14

[56] References Cited UNITED STATES PATENTS 3,490,843 l/l970 Charlap et a]. 355/14 3,711,198 l/l973 Nordine 355/14 X Primary ExaminerRobert P. Greiner Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher [57] ABSTRACT An electrophotographic copying apparatus in which an original and a copy sheet are advanced during reproduction in a downwards direction along mutually spaced, substantially vertical conveying paths, start positions for the advancement of the original and the copy sheet being defined by stop members inserted into the respective conveying paths, which stop members are retracted from their inserted positions in a timed sequence with the start of a main driving system, the advancement of a copy sheet from a sheet supply to the copy sheet conveying path and the operation of a corona charging unit and an exposure lamp, by programming means including a single disc-shaped timing member which is mounted for rotation in the apparatus and is coupled with the main driving system, said timing member actuating all of the control functions in a correctly timed sequence during a single revolution.

7 Claims, 13 Drawing Figures PATENTEL HUN 9 I974 SHEET 10F 7 FIG. 1

PATENTELHUVIQIW 7 3,848,991

SHEET 30F 7 FIG. 3

PATENTEL WV 1 9 I974 SHEET 4 OF 7 FIG.

PATENTEL HUV 1 9 I974 SHEET 6 OF 7 ELECTROPIIOTOGRAPI-IIC COPYING APPARATUS The present invention relates to an electrophoto- I BACKGROUND OF THE INVENTION A copying apparatus of this kind is described in applicants copending U.S. patent application Ser. No. 358,325 filed on May 8, 1973 which is a continuationin-part of applicants prior U.S. application Ser. No. 112,565 now abandoned. This copying apparatus has the advantage of being of a simple structure, so that it can be manufactured and sold at a low price and presenting an easy operation for the user. Above all, the apparatus is of a limited size so that a minimum of space is required for its installation due to the fact, inter alia, that accessibility is only required to the front of the apparatus which may therefore be hanged directly on a wall.

In the art of electrophotographic copying, various control systems are known for controlling the processing steps to which a copy sheet is subjected in a copying apparatus, such as electrostatical charging, exposure, development and drying, such control systems incorporating devices of a purely electronic, an electromechanical and a purely mechanical nature. It applies to all such control systems as a common requirement that the individual processing steps should be performed automatically in a prescribed sequence, so that the only manual operation of the apparatus consists in pushing a start button and, if necessary, controlling the light intensity for the exposure by means, for example, of an adjustable light screen incorporated in the optical system of the apparatus. Thus, the individual processing steps are often controlled by micro switches, sensing members of which are arranged in the conveying path for the copy sheet, so that the start and the termination of each individual processing step is controlled directly through the advancement of the copy sheet. It is well known, however, that considerable adjustment problems often arise in connection with such micro switches, since the part of the sensing member to be actuated by a paper sheet should be adjusted to a very accurate position in the conveying path. Furthermore the control of processing steps involving the movement of various mechanical components by means of such micro switches necessitates the use of solenoid actuated devices for imitating that movement.

A particular advantage of a copying apparatus of the above-mentioned kind is connected with the fact that before the reproduction process is started the original and the copy sheet are kept by their own weights in mutually spaced, substantially vertical start positions in which the lower edges of the original and the copy sheet are engaged by stop members inserted in their respective conveying paths, the rollers of a first pair of advancing rollers in each conveying path being arranged above said stop members and being kept in a mutually spaced relation in said start position. By simultaneously retracting the stop members from a conveying path and coupling together the said rollers in the same conveying path, advancement of the original on the copy sheet, respectively, is started. This measure may be utilized to obtain a correct alignment of the leading edges of the original and the copy sheet at the beginning of the exposure step either by such a proportioning of the conveying paths for the original and the copy sheet, respectively, that the distance between the step members and the upper edge of an exposure window is the same in both conveying paths or by employing a time delay from the retraction of the stop members from the copy sheet conveying path to the retraction of the stop members from the original conveying path. However, the retraction of such stop members from a conveying path and the coupling together of two rollers performed simultaneously therewith represent a typical processing step of the kind involving the movement of purely mechanical components which when being imitated by sensor controlled micro switches can only be released by solenoid controlled actuating devices. In an apparatus of the kind set forth having the advantages of a low price and a compact, space-saving structure, the use of such actuating device will result in an undesiderable complication of the mechanical structure and an increase of the manufacturing costs.

SUMMARY OF THE INVENTION It is an object of the invention to provide an electrophotographic copying apparatus of the abovementioned compact structure in which the individual processing steps are controlled by simple and reliably operating programming means requiring only a minimum of space and securing an accurate synchronism between the advancements of the original and the copy sheet, the only manual operation still consisting in pushing a start button and controlling the light intensity, if necessary.

According to the invention there is provided an electrophotographic copying apparatus, comprising mutually spaced, substantially vertical first and second conveying paths for an original to be reproduced and a copy sheet having a photosensitive surface to receive a reproduction of said original, respectively;

a main driving system including an electric motor for advancing the original and the copy sheet in a downwards direction along said conveying paths;

an exposure lamp arranged at said first conveying path for illuminating the original;

a corona charging device, an exposure window, a developing device and a drying device arranged in order af succession in the advancing direction of the copy sheet along said second conveying path;

a supply of copy sheets arranged above said second conveying path;

a catch mechanism for taking off a single copy sheet at a time from said sheet supply and advancing said sheet towards said second conveying path;

spring biased stop members arranged to be inserted into said first and second conveying paths for defining substantially vertical original and a copy sheet start positions at the upper ends of said conveying paths, the original and the copy sheet being kept in these start positions by their own weight;

and a pair of advancing rollers arranged in each of said conveying paths above said stop members, the rollers of each of said roller pairs being removed from each other when an original and a copy sheet are present in said start positions,

i the spring biased stop members from each of said conwherein the improvement comprises that programming means are provided, which comprise a first switching device for switching on and off the current supply to the electric motor of the main driving system; 5

a second switching device for switching on and off the current supply to the corona charging device and the exposure lamp;

first and second control mechanisms for retracting 0 veyingpaths and simultaneously coupling together the rollers of said rollers of said roller pairs;

a number of actuating members for actuating and deactuating said first and second switching devices and said first and second switching devices and said first and second control mechanisms;

a manually operated start button to influence the actuating member for said first switching device;

a cam wheel connected with said catch mechanism;

and a single, circular disc-shaped timing member; mounted for rotation in the copying apparatus and cou-Y' pled with the main driving system, said timing member being provided on one lateral surface with a number of radially displaced, substantially circular actuating surface sections, each of which is in operative engagement with one of said actuating members to operate said members in a timed sequence during a single revolution of the timing member, the surface section associated with the actuating member for the first switching device being formed so as to operate said actuating memher to actuate the first switching device to switch on the current supply to the electric motor of the main driving system when said actuating member is influenced by said start button, whereby rotation of the timing member will be started, the timing member furthermore having a number of teeth arranged in a circular are outside said actuating surface sections so as to get in operative engagement with said cam wheel in a timed sequence with the operation of said actuating members.

By these programming means all the individual steps of the reproduction process are controlled by said timing member. As soon as the timing member has started its rotation which is initiated through operation of the start button, all the necessary actuations of the parts which are to be mechanically moved during the individual steps are performed in the course ofa single revolution of the timing member by purely mechanical actuation members without the use of solenoid controlled actuators. As a result, a very reliable operation is obtained in which the need of adjusting operations is reduced to a minimum.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 5 to 8 are sectional views along the lines V-V, VIVI, VIIVII and VIIIVIII, respectively, in FIG. 4; and.

FIGS. 9 to 13 illustrate various rotational phases of the timing member shown i FIGS. 4 to 8.

DETAILED DESCRIPTION In FIG. 1 an electrophotographic copying apparatus of the kind described in applicants above-mentioned US. patent application Ser. No. 358,325 is diagrammatically shown in a sectional view along a vertical plane. In such an apparatus the original is scanned line by line during exposure under synchronous advancement of the original and the copy sheet by means of a stationary optical system which forms an image of that part of the original which is momentarily passing an exposure window in the original conveying path at an exposure station disposed at the conveying path of the copy sheet.

Copy sheets are taken individually from a sheet supply l in the apparatus by means ofa turnable frictional catch mechanism 2 which on actuation performs a single complete revolution during part of which it catches the nearest copy sheet in sheet supply 1, said copy sheet being thereby advanced towards a start position for the advancement of the copy sheet, the sheet being held vertically by its own weight in said position, the lower limit of which is defined by stop members 3 which in the rest condition of the apparatus are inserted in the copy sheet conveying path immediately below the uppermost pair of advancing rollers in said path, the rollers 4 and 5 of said roller pair being kept in a mutually spaced relation in said start position.

When reproduction has to take place stop members 3 are retracted from the copy sheet conveying path and simultaneously rollers 4 and 5 are coupled together such as explained in the following. The copy sheet is thereafter in a manner known per se advanced through a corona charging unit 6 in which the photosensitive surface of the sheet is electrostatically charged, an exposure station 7 at which the sheet is'exposed to the image of an original, a development station 8 and a drying device 9 in order of succession, the copy sheet finally leaving the apparatus through a discharge opening 10 at the bottom of the apparatus. The copy sheet advancement is performed by means of a roller pair I l,

l2 between exposure station 7 and development station 8, a roller pair l3, 14 between development station 8 and drying device 9, said roller pair also serving to sweep off excess developer liquid from the copy sheet,

anda roller pair

15, 16 arranged at discharge opening 10.

An original to be reproduced is inserted from above behind a cover 17 which is pivotably mounted at the front of the apparatus in a manner not shown, until it assumes a start position for the advancement of the original, in which the original is kept substantially ve rtically by its own weight in the same way as the copy sheet in its start position, the lower limit of the original start position being defined by stop members 18 which in the rest condition of the apparatus are inserted in the original conveying path immediately below the uppermost pair of advancing rollers in said path, the rollers 19 and 20 of said pair being kept in a mutually spaced relation in said start position. When the copy sheet has started to move from its start position through the corona charging unit 6 towards the exposure station 7,

stop members 18 are retracted from the original conveying path and simultaneously rollers 19 and 20 are coupled together whereby the original will beadvanced in synchronism with the advancement of the copy sheet past an exposure window 21 through which it is imaged onto the copy sheet by means of an optical system incorporating in a manner known per se an exposure lamp 22, two

inclined mirrors

23 and 24, a lens system 25 having a reflecting mirror 26 and a light screen member 27 for adjusting the light intensity. After having passed the exposure window 21 the original is discharged from the apparatus below the cover 17 by means of a

roller pair

28, 29.

FIG. 2 shows schematically the driving means for the advancement of the original and the copy sheet in the apparatus shown in FIG. 1. The driven

rollers

4, 11, 14, 15 and 19, 28 in the conveying paths for the copy sheet and the original, respectively, are rigidly connected with sprocket wheels which are designated by the same reference numerals as their associated rollers, but provided with strokes. Roller 14 and sprocket wheel 14 are mounted on a shaft 30 which is connected with an electric motor 31 through transmission means not shown, while sprocket wheels 4', ll, 14, 15, 19' 0g 28 are connected together by a chain 32 and are proportioned in dependence on the diameters of their associated rollers to that all of these rollers in operation of the apparatus rotate with equal peripheral velocities in the directions indicated by arrows.

To complete a reproduction process in the apparatus shown in FIG. 1 the following individual operations have to be performed:

1. Starting the driving means shown in FIG. 2;

2. Advancing a single copy sheet from sheet supply 1 by means of catch mechanism 2 towards the start position;

3. Switching on corona charging unit 6 and exposure lamp 22;

4. Retracting stop members 3 from the copy sheet conveying path and coupling together rollers 4 and 5. Retracting stop member 18 from the original conveying path and coupling together rollers 19 and 20;

6. Switching off corona charging unit 6 and exposure lamps 22; and

7. Stopping the driving means shown in FIG. 2.

According to the invention, all these operations are controlled by programming means incorporating a single rotating timing member so that the only manual operation consists in pushing a start button shown at 33. In the embodiment illustrated on the drawing said timing member is constituted by a toothed timing wheel 34 meshing with a gear wheel 35 which is rigidly connected with a sprocket wheel 36 meshing with chain 32.

The function of timing wheel 34 and the actuating mechanism connected therewith will be explained in detail with reference to the perspective view shown in FIG. 3. The driving means shown in FIG. 2 are started and stopped and the corona charging unit 6 and the exposure lamp 22 are switched on and off by means of

micro switches

37, 38 and 39, respectively, having operation members and 41, operation member 41 being common to

contacts

38 and 39 which are incorporated in the current supply circuits for corona charging unit 6 an exposure lamp 22, respectively.

Switches

37, 38 and 39 which are arranged at the opposite side of the apparatus relative to the driving means shown in FIG. 2 are switched by operation members 40 and 41 by axial displacement of

switch actuating rods

42 and 43, respectively, which extend throughout the width of the apparatus and at right angles to timing wheel 34, said switch actuating rods being biased in the direction towards timing wheel 34 such as indicated by arrows. The ends of

switch actuating rods

42 and 43 remote from switches 37 to 39 are situated in

guide grooves

44 and 45, respectively, which are formed in one lateral surface of timing wheel 34.

Stop members 3 in the copy sheet conveying path and stop members 18 in the original conveying path are formed integrally with

bars

46 and 47, respectively, engaging

control rods

46 and 47 which are rigidly connected with actuating

shafts

48 and 49, respectively, pivotably journalled in the apparatus, said actuating shafts being again rigidly connected with

cam members

50 and 51, respectively, each of said cam members being in engagement with a cam surface formed in timing wheel 34. These cam surfaces are constituted by oppositely

curved side walls

52 and 53, respectively of a further guide groove 54 formed in timing wheel 34. The ends of

bars

46 and 47 with their associated stop members are restricted to movement in a horizontal plane such as shown for bar 47, the ends of the bars being engaged by grooves such as shown at 47" which are formed in bearings secured to stationary walls of the apparatus.

Frictional catch mechanism 2 which serves to advance single copy sheets from sheet supply 1 are mounted on a shaft 55 on one end of which a pin wheel 56 is secured said wheel being provided on one side with a member of pins 57, in the embodiment shown six pins, to engage a corresponding number of teeth formed in the same lateral surface of timing wheel 34 as

guide grooves

44, 45 and 54.

The detailed structure oftiming wheel 34 which may be moulded in one piece from a plastic material will be apparent from the plane view shown in FIG. 4 and the sectional views shown in FIGS. Sto 8. The axial displacement of

switch actuating rods

42 and 43 for actuating switch operation members 40 and 41, respectively to change over

micro switches

37 and 38, 39 is accomplished in that each of the corresponding circular and

concentric guide grooves

44 and 45 is divided into length portions, the bottom levels of which are displaced relative to each other, one bottom level corresponding to the actuated state and the other to the deactuated state of the associated switch. Thus, guide groove 45 associated with switch actuating rod 43 which serves for switching on and off corona charging unit 6 and exposure lamp 22 is divided into two

lenght portions

59 and 60 having mutually displaced bottom levels. As shown in FIGS. 6 and 8, the bottom face of the guide groove is inclined at the bottom

level displacement junctions

61 and 62 between the two

length portions

59 and 60, whereby switch actuating rod 43 when being passed by these junctions is subjected to the desired axial displacement for changing over switches '38 and 39, said switches being actuated when switch actuating rod 43 is passed by junction 6] to switch on corona charging unit 6 and exposure lamp 22 and being actuated to switch off said parts, when rod 43 is passed by junction 62. The portion of

junctions

61 and 62 are chosen in dependance of the portion of switch actuating rod 43 relative to timing member 34 so that switching on and off of

switches

38 and 39 take place to the desired instants during a reproduction process.

In a similar manner, guide groove 44 for switch actuating rod 42 serving to change over the micro switch 37 associated with the driving means shown in FIG. 2 is divided into

length portions

63 and 64 corresponding to the deactuated and actuated states, respectively, of switch 37. However, guide groove 44 is barried at the junction between

length portions

63 and 64 on part of its width by a stop bar 65 which is engaged in the rest condition of the apparatus by the end of switch actuating rod 42 situated in guide groove 44. As shown in FIG. 1, this end of switch actuating rod 42 is positioned in an operative relation to start button 33, the switch actuating rod being supported in an inclined slot in a partition wall in the apparatus so that switch actuating rod 42 will be displaced in a radial direction of timing wheel 34, when start button 33 is depressed. Thereby, switch actuating rod 42 will be displaced from its position in length portion 63 in engagement with stop bar 65 to the part of the width of guide groove 44 which is not barred by stop bar 65, the bottom level of said part of the guide groove being the same as that of length portion 64, switch actuating rod 42 being, thereby, operated to actuate micro switch 37. As a result thereof, the driving means illustrated in FIG. 2 are started and timing wheel 34 begins its rotation. Since switch actuating rod 42 is biased as indicated by an arrow in FIG. 1

towards that part of the width of guide groove 44 which is barred by stop bar 65, it will subsequent to the passage of the. stop bar be returned in a radial direction to said part of the guide groove. Normally, switch actuating rod 42 will be operated to deactuate micro switch 37 and stop the driving means illustrated in FIG. 2, when it is passed by the inclined junction 67 between the above-mentioned

length portions

64 and 63. However, guide groove 44 is formed so that it is possible by depressing start button subsequent to the switching off of the corona charging unit and the exposure lamp to prevent the driving means from being stopped, the part of the width of guide groove 44 which is not barred by stop bar 65 having along a corresponding length portion 68, a third bottom level which is different from the bottom levels of

length portions

63 and 64, but which corresponds to the actuated state of micro switch 37 just like the bottom level oflength portion 64. Thus, by a radial displacement resulting from depression of start button 33, which actuating rod 42 will be moved into 4 length portion 68 in stead of assuming the bottom level of length portion 63 by being passed by inclined junction 67. Thereafter, the end of switch actuating rod 42 will again be displaced axially to assume the bottom level of length portion 64 by being passed by junction 69 between

length portions

68 and 64.

The opposite side walls of guide groove 54 in timing wheel 34 which serve as cam faces for

cam members

50 and 51 to retract

stop members

3 and 18 away from the conveying paths for the copy sheet and the original, respectively, are formed with abrupt surface discontinuities as shown at 70 and 71, by the passage of which

cam members

50 and 51 will be subjected to such a radial displacement relative to timing wheel 34 that stop

members

3 and 18 as a result of the turning of actuating

shafts

48 and 49, respectively, caused thereby will be pivoted out of the conveying paths of the copy sheet and the original respectively.

The various rotational phases of timing wheel 34 are illustrated in FIGS. 9 to 13 which also show the positions of

switch actuating rods

42 and 43 and the parts of

cam members

50 and 51 which are in engagement with cam faces 52 and 53, respectively, of timing wheel 34. In FIG. 9 the start position for the rotation of timing wheel 34 is shown, in which position switch actuating rod 42 engages stop bar 65. The driving means are actuated by a radial displacement of the switch actuating rod to the position shown by a dotted circle, when the start button 33 is operated, whereby timing wheel 34 begins its rotation. In the position shown in FIG. 10, in which timing wheel 34 has rotated about 35 from the start position, teeth 58 on timing wheel 34 has rotated pin wheel 56 in catch mechanism 2 by such an amount that a single copy sheet from sheet supply 1 has been advanced to the copy sheet start position. Furthermore, in this position switch actuating rod 43 is passed by junction 61 in guide groove 45, whereby corona charging unit 6 and exposure lamp 22 are switched on, while cam member 50 is passed by discontinuity of cam face 52, whereby stop member 3 are retracted from the copy sheet conveying path and advancing rollers 4 and 5 are coupled together. In the position shown in FIG. 11, in which timing wheel 34 in the embodiment shown has rotated 45,3 from the start position, cam member 51 is passed by discontinuity 71 of cam face 53, whereby stop members 18 are retracted from the original conveying path and advancing rollers 19 and 20 are coupled together. The relative angular positions of

discontinuities

70 and 71 is chosen in dependence on the relative positions of

cam members

50 and 51 so that the time delay between the positions shown in FIGS. 10 and 11 corresponds to the difference between the distance from stop members 3 to the upper edge of the window in the exposure station associated with the copy sheet conveying path and the distance between stop member 18 and the upper edge of exposure window 21 in the original conveying path. In the position shown in FIG. 12, in which timing wheel 34 in the embodiment shown has rotated about 235 from the start position, switch actuating rod 43 is passed by junction 62 in guide groove 45, whereby corona charging unit 6 and exposure lamp 22 are switched off. In the position shown in FIG. 13, in which timing wheel 34 has rotated about 325 from the start position switch actuating rod 42 will be passed byjunction 67 in guide groove 44, provided it has not already been radially displaced by operation of start button 33, whereby micro switch 37 will be deactuated to stop the driving means, so that timing wheel reassumes the position shown in FIG. 9. If start button 33 has been operated before the timing wheel reaches the position shown in FIG. 13, the deactuation of switch actuating rod 42 will be prevented in the manner already explained.

As already mentioned it is necessary in order to obtain an accurate positioning of the original and the copy sheet in their respective start positions in the copying apparatus according to the invention that rollers 4 and 5 in the first pair of advancing rollers in the copy sheet conveying path as well as rollers 19 and 20 in the first pair of advancing rollers in the original conveying path are kept in a mutually spaced relation in the rest condition of the apparatus. According to the invention this is obtained in that the non-driven roller in each of said roller pairs, i.e., rollers and 20, is resiliently supported and is biased towards engagement with the driven roller in the same roller pair, i.e. rollers 4 and 19, respectively, the support for said non-driven roller and the stop member associated with the conveying path in question being formed so that the stop member in the postion in which it is inserted in the conveying path exerts a force on said roller support in a direction opposite to that of the applied bias, whereby the non-driven roller is displaced away from the position, in which it engages the driven roller. As soon as the stop member is actuated from timing wheel 34 to be retracted from the conveying path in question, the nondriven roller 5 or will be brought into engagement with the driven roller 4 or 19. Thus, in the embodiment shown in FIG. 1 of the copying apparatus according to the invention the

non-driven rollers

20 and 29 in the original conveying path are mounted on a support member 72 which is resiliently suspended relative to cover 17, so that

rollers

20 and 29 are biased towards engagement with rollers 19 and 28, respectively. Just below roller 20 support member 72 has a protusion 73 facing the original conveying path for being engaged by stop member 18 in the position, in which the stop member is inserted in the conveying path. In a similar manner, non-driven rollers 5 and 12 in roller pairs 4, 5 and 11, 12 in the copy sheet conveying path are mounted on a support member 74 which is resiliently supported relative to a back wall 75 of the apparatus such as shown schematically in FIG. 1 and is biased towards the position, in which both rollers 5 and 12 engage rollers 4 and 11, respectively. Support member 74 has a form so that part of said memberjust below roller 5 forms an abutment for stop member 3 in the position, in which the stop member is inserted in the copy sheet conveying path. As shown in FIG. 1, support member 74 may also carry the backward half part of corona charging unit 6, so that direct access to the portion of the copy sheet conveying path extending between roller pairs 4, 5 and ll, 12 may be obtained by opening the apparatus at the back wall.

What is claimed is:

1. An electrophotographic copying apparatus, comprising mutually spaced, substantially vertical first and second conveying paths for an original to be reproduced and a copy sheet having a photosensitive surface to receive a reproduction of said original, respectively;

a corona charging device, an exposure window, a developing device and a drying device arranged in order of succession in the advancing direction of the copy sheet along said second conveying path;

a supply of copy sheets arranged above said second conveying path;

spring biased stop members arranged to be inserted into said first and second conveying paths for defining substantially vertical original and copy sheet start positions at the upper ends of said conveying paths, the original and the copy sheet being kept in these start positions by their own weight;

wherein the improvement comprises that programming means are provided, which comprise a first switching device for switching on and off the current supply to the electric motor of the main driving system;

first and second control mechanisms for retracting the spring biased stop members from each of said conveying paths and simultaneously coupling together the rollers of said roller pairs;

a number of actuating members for actuating and deactuating said'first and second switching devices and said first and second control mechanisms;

at mannually operated start button to influence the actuating member for said first switching device;

a cam wheel connected with said catch mechanism;

and' a single, circular disc-shaped timing member mounted for rotation in the copying apparatus and coupled with the main driving system, said timing member being provided on one lateral surface with a number of radially displaced, substantially circular actuating surface sections, each of which is in operative engagement with one of said actuating members to operate said members in a timed sequence during a single revolution of the timing member, the surface section associated with the actuating member for the first switching device being formed so as to operate said actuating member to actuate the first switching device to switch on the current supply to the electric motor of the main driving system when said actuating member is influenced by said start button, whereby rotation of the timing member will be started, the timing member furthermore having a number of teeth arranged in a circular arc outside said actuating surface sections so as to get in operative engagement with said cam wheel in a timed sequence with the operation of said actuating members.

2. An electrophotographic copying apparatus as claimed in claim 1, wherein the actuating member for the first switching device is formed so as to prevent deactuation of said switching device when the start button is reoperated before the termination of said single revolution of the timing member.

3. An electrophotographic copying apparatus as claimed in claim 1, wherein the actuating members for the first and second switching devices are constituted by axially displaceable switch actuating rods extending at right angles to said one lateral surface of the timing member and being biased in the axial direction towards the timing member, the associated actuating surface sections on the timing member being constituted by bottom faces of substantially circular guide grooves for said switch actuating rods, each of said bottom faces being subject to a level displacement between the parts of the length of the guide groove corresponding to the actuated and deactuated state for the associated switching device, respectively.

4. An electrophotographic copying apparatus as claimed in claim 3, wherein the guide groove for the switch actuating rod associated with said first switching device is barred in a given position on part of its width by a stop bar, one side of which serves to engage the switch actuating rod in the rest condition of the apparatus, the bottom face of said part of the guide groove lying in said given position at a first level corresponding to the deactuated state of the first switching device, the end of the switch actuating rod situated in the guide groove being adapted to be engaged by said start but- .ton at operation of the start button so as to be radially displaceable relative to the timing member to the part of the width of the guide groove which is not barred by said stop bar, the bottom face of the lastmentioned part of the guide groove assuming, in said given position, together with the bottom face of the guide groove on the other side of the stop bar a second level corresponding to the actuated state of the first switching device, the switch actuating rod being biased in the radial direction of the timing member towards the part of the width of the guide groove which is barred by the stop bar.

5. An electrophotographic copying apparatus as claimed in claim 4, wherein the bottom face of said part of the width of said guide groove which is not barred by said stop bars lies through a portion at its length which during rotation of the timing member passes said switch actuating rod subsequent to deactuation of said second switching device at a third level which is different from said first and second bottom face levels, but corresponds to the actuated state of said first switching device, whereby the switch actuating rod by being radially displaced as a result of operation of the start button will be prevented form assuming said first bottom face level.

6. An electrophotographic copying machine as claimed in claim 1, wherein the control mechanisms for retracting said stop members from said first and second conveying paths comprise shafts which are pivotably journalled in the apparatus and each of which is rigidly connected, on one hand, with the stop members associated with one of said conveying paths and, on the other hand, with the actuating member associated with said stop members, each of said lastmentioned actuating members being constituted by a cam member and the corresponding actuating surface section on the timing member being constituted by. a cam surface, said cam surface forming opposite, curved lateral surfaces of a further sustantially circular guide groove, in each of which lateral surfaces such a discontinuity is provided in a position at which actuation'of the corresponding cam member has to take place that said cam member when being passed by said discontinuity will actuate the corresponding shaft to pivot the stop members away from the associated conveying path.

7. An electrophotographic copying machine as claimed in claim 6, wherein each of the roller pairs arranged above the stop members associated with said first and second conveying paths, respectively, comprises a non-driven roller, a resilient support for said roller and a driven roller coupled with said main driving system, said support being biased towards engagement of the non-driven roller with the driven roller, the stop members for the associated conveying path being formed so as to exert in the positionin which they are inserted in the conveying path, a force on said support against the direction of the bias, whereby the nondriven roller will be kept in a position spaced from the driven roller and may be brought into engagement with said roller by retracting the stop members from the conveying path.

Claims

1. An electrophotographic copying apparatus, comprising mutually spaced, substantially vertical first and second conveying paths for an original to be reproduced and a copy sheet having a photosensitive surface to receive a reproduction of said original, respectively; a main driving system including an electric motor for advancing the original and the copy sheet in a downwards direction along said conveying paths; an exposure lamp arranged at said first conveying path for illuminating the original; a corona charging device, an exposure window, a developing device and a drying device arranged in order of succession in the advancing direction of the copy sheet along said second conveying path; a supply of copy sheets arranged above said second conveying path; a catch mechanism for taking off a single copy sheet at a time from said sheet supply and advancing said sheet towards said second conveying path; spring biased stop members arranged to be inserted into said first and second conveying paths for defining substantially vertical original and copy sheet start positions at the upper ends of said conveying paths, the original and the copy sheet being kept in these start positions by their own weight; and a pair of advancing rollers arranged in each of said conveying paths above said stop members, the rollers of each of said roller pairs Being removed from each other when an original and a copy sheet are present in said start positions, wherein the improvement comprises that programming means are provided, which comprise a first switching device for switching on and off the current supply to the electric motor of the main driving system; a second switching device for switching on and off the current supply to the corona charging device and the exposure lamp; first and second control mechanisms for retracting the spring biased stop members from each of said conveying paths and simultaneously coupling together the rollers of said roller pairs; a number of actuating members for actuating and deactuating said first and second switching devices and said first and second control mechanisms; a mannually operated start button to influence the actuating member for said first switching device; a cam wheel connected with said catch mechanism; and a single, circular disc-shaped timing member mounted for rotation in the copying apparatus and coupled with the main driving system, said timing member being provided on one lateral surface with a number of radially displaced, substantially circular actuating surface sections, each of which is in operative engagement with one of said actuating members to operate said members in a timed sequence during a single revolution of the timing member, the surface section associated with the actuating member for the first switching device being formed so as to operate said actuating member to actuate the first switching device to switch on the current supply to the electric motor of the main driving system when said actuating member is influenced by said start button, whereby rotation of the timing member will be started, the timing member furthermore having a number of teeth arranged in a circular arc outside said actuating surface sections so as to get in operative engagement with said cam wheel in a timed sequence with the operation of said actuating members.

4. An electrophotographic copying apparatus as claimed in claim 3, wherein the guide groove for the switch actuating rod associated with said first switching device is barred in a given position on part of its width by a stop bar, one side of which serves to engage the switch actuating rod in the rest condition of the apparatus, the bottom face of said part of the guide groove lying in said given position at a first level corresponding to the deactuated state of the first switching device, the end of the switch actuating rod situated in the guide groove being adapted to be engaged by said start button at operation of the start button so as to be radially displaceable relative to the timing member to the part of the width of the guide groove which is not barred by said stop bar, the bottom face of the lastmentioned part of the guide groove assuming, in said given position, together with the bottom face of the guide groove on the other side of the stop bar a second level corresponDing to the actuated state of the first switching device, the switch actuating rod being biased in the radial direction of the timing member towards the part of the width of the guide groove which is barred by the stop bar.

6. An electrophotographic copying machine as claimed in claim 1, wherein the control mechanisms for retracting said stop members from said first and second conveying paths comprise shafts which are pivotably journalled in the apparatus and each of which is rigidly connected, on one hand, with the stop members associated with one of said conveying paths and, on the other hand, with the actuating member associated with said stop members, each of said lastmentioned actuating members being constituted by a cam member and the corresponding actuating surface section on the timing member being constituted by a cam surface, said cam surface forming opposite, curved lateral surfaces of a further sustantially circular guide groove, in each of which lateral surfaces such a discontinuity is provided in a position at which actuation of the corresponding cam member has to take place that said cam member when being passed by said discontinuity will actuate the corresponding shaft to pivot the stop members away from the associated conveying path.

7. An electrophotographic copying machine as claimed in claim 6, wherein each of the roller pairs arranged above the stop members associated with said first and second conveying paths, respectively, comprises a non-driven roller, a resilient support for said roller and a driven roller coupled with said main driving system, said support being biased towards engagement of the non-driven roller with the driven roller, the stop members for the associated conveying path being formed so as to exert in the position in which they are inserted in the conveying path, a force on said support against the direction of the bias, whereby the non-driven roller will be kept in a position spaced from the driven roller and may be brought into engagement with said roller by retracting the stop members from the conveying path.