US3861796A

US3861796A - Electrophotographic copying machine

Info

Publication number: US3861796A
Application number: US213377A
Authority: US
Inventors: Susumu Tanaka; Yuji Enoguchi; Isao Iizaka
Original assignee: Minolta Co Ltd
Current assignee: Minolta Co Ltd
Priority date: 1970-12-30
Filing date: 1971-12-29
Publication date: 1975-01-21
Anticipated expiration: 1992-01-21

Abstract

In an electrophotographic copying machine the original is supported by a reciprocating carriage and an image is projected to an exposure window and onto a flexible sheet-like photosensitive member which is movable along a conveying path positioned along the imaging plane of the optical system and in parallel with the reciprocating carriage. A charging device and transfer roller mechanism are mounted on opposite sides of the exposure window. The latent image is transferred to a transfer material by contact of the material with the photosensitive member, and means are provided for separating the sheet-like material from the photosensitive member and transporting it to a developing device.

Description

[ Jan. 21, 1975 ELECTROPHOTOGRAPHIC COPYING MACHINE [75] Inventors: Susumu Tanaka, Sakai; Yuji Primary Examiner-Samuel S. Matthews Enoguchi, Higashiosaka; Isao lizaka, Assistant ExammerKenneth C. Hutchison Toyokawa, all of Japan [73] Assignee: Minolta Camera Kabushiki Kaisha,

Attorney, Agent, or Firm-Watson, Cole, Grindle 8L Watson [57] ABSTRACT In an electrophotographic copying machine the origi- Osaka-shi, Osaka-fu, Japan Dec. 29, 1971 [22] Filed:

nal is supported by a reciprocating carriage and an image is projected to an exposure window and onto a flexible sheet- 21 Appl. No.: 213,377

like photosensitive member which is movable along a conveying path positioned along the G03g 15/22 imaging plane of the optical system and in parallel 355/3 R, 8, 1O 1 1, 12, with the reciprocating carriage. A charging device and transfer roller mechanism are mounted on opposite sides of the exposure window. The latent image is transferred to a transfer material by contact of the material with the photosensitive member, and means are provided for separating the sheet-like material from the photosensitive member and transporting it to a developing device.

4 Claims, 13 Drawing Figures References Cited UNITED STATES PATENTS Schwertz....

m t nbbe me 6 m M. UC O0 77 99 11 35 [51] Int. [58] Field of Search 3,497,297 2/1970 Robinson et al. 3,499,709

PATENTEUJANZI I975 SHEEI 2' OF 5 3 82 3% 5m: VJ

PATENTEDJANZ 1191s SHEEI 5 0f 5 .5 mm: mm: 2; wmsv ELECTROPHOTOGRAPHIC COPYING MACHINE BACKGROUND OF THE INVENTION The present invention relates to a copying machine capable of copying a thick original such as a book and the like by making use of the Carlson process, and more particularly, to an electrophotographic copying machine in which a dielectric transfer sheet is contacted with an electrostatic latent image of the original formed on a photosensitive plate so that the electrostatic latent image is transferred thereon, and the electrostatic latent image transferred onto the dielectric transfer sheet is developed by an aqueous toner developer and fixed by drying so as to complete a copy thereof.

Conventional copying machines are represented by a xerography type copying machine and an Electrofax type copying machine. The former has been put to practical use because a plurality of copies can be speedily obtained and the copies are light and therefore easily handled. However, it has the disadvantage in that a photosensitive substance thereof should be, when it is fatigued and degenerated, replaced together with a drum on the surface of which the photosensitive substance is integrally formed by an evaporation process or the like, resulting in a high replacement cost. Also it is not possible to obtain a copy of a sharp picture quality, since the exposure of a picture image is carried out while an original picture projecting optical system, an original picture illuminating means and a projecting lens are together travelling relative to the peripheral speed of the drum-like photosensitive substance so that the length of the light path from the original picture to the photosensitive substance is varied. Further, owing to the physical processes such as the cascade developing, transferring cleaning and the like performed directly on the photosensitive substance, the degrading of the picture quality due to any possible damage or degeneration of the photosensitive substance is inevitable. Finally, on account of the image making process and the drum-like photosensitive substance of which the structure is made appropriate thereto, the structural size of the copying machine itself is remarkably large.

The latter type copying machine has been put to practical use because its picture making processes have been simplified and a sheet-like photosensitive substance is used so that the copying machine itself is able to be made much smaller than the former type copying machine. Also the copying time for obtaining the first copy is faster and the copy is remarkably sharp in comparison with that of the former type machine. However, the most remarkable disadvantage thereof resides in that the obtained copy is made of a photosensitive sheet so that it cannot be handled as easily as a dielectric sheet.

Even though these conventional practical copying machines have been widely used in accordance with their respective merits, neither of them is completely a satisfactory copying machine on account of its individual disadvantages as described above.

Such an image making method wherein an electrostatic latent image formed on a photosensitive substance is transferred to a dielectric paper and then developed has been known herefore as the TESl process. The term applied to a variety of methods, one of which is the method proposed in Japanese Pat. No. 42-19757,

and this proposed method is well known as the simplest TESl process, which method comprises the following steps: forming an electrostatic latent image on a photosensitive substance, contacting a dielectric sheet with the photosensitive substance, grounding both bases of the dielectric sheet and the photosensitive substance. and thereafter separating the dielectric sheet from the photosensitive substance so that the electronic latent image can be thereby transferred to the dielectric sheet. In this method the photosensitive substance is not imparied by any physical step since the electrostatic latent image on the photosensitive substance is merely electrically transferred. Additionally a copy is made on a dielectric sheet. The reason why no practical copying machine using this method has been realized heretofore resides in that the density of a copy obtained by making use of a conventional photosensitive substance is too low, when the photosensitive substance is repeatedly put to use therein, to obtain a sharp copy because of the effects of previous exposures upon the succeeding exposure, so that it was therefore difficult to carry out a speedy copying operation.

SUMMARY OF THE INVENTION It is therefore one object of the present invention to provide an electrophotographic copying machine in which an optical system is fixed in such a manner that the length of a light path from the original to a photosensitive plate is not varied due to the relative displacement between the original and the photosensitive plate. An electrostatic latent image consisting of the mirror image of the original is formed on the photosensitive plate; then the electrostatic latent image is transferred to a transfer sheet so as to obtain a sharp copy of the original.

It is another object of the present invention to provide an electrophotographic copying machine in which no physical process such as cascade development and the like is directly applied to a photosensitive plate in order to avoid the degradation of the picture quality due to any damage or degeneration of the photosensitive plate caused thereby.

It is still another object of the present invention to provide an electrophotographic copying machine in which only the face of the transfer sheet having a latent image transferred thereto is capable of being speedily developed by coming into contact with a developer liquid, and the back face thereof is not immersed in the developer liquid so that the transfer sheet can be speedily dried and therefore speedy copying can be accordingly realized.

it is still further another object of the present invention to provide an electrophotographic copying machine of which the size is minimized by using a sheetlike photosensitive substance capable of being easily exchanged, that is, easily removed from and reinstalled in the copying machine.

It is yet another object of the present invention to provide an electrophotographic copying machine in which a photosensitive substance is used having the mechanical property of strength and flexibility, when it is adapted to the copying machine in accordance with the present invention, and that is capable of being charged with a high potential such as nearly lOOOV or more, and having a high sensitivity such that the exposure of a picture image thereon can be effectively carried out by only several Lux-sec without being impaired by the effects of previous exposures, and which is therefore capable of forming an electrostatic latent image with a high contrast and a high resolving power, and by means of which the transfer of the electrostatic latent image can be efficiently carried into effect by making use of the aforesaid TESI process.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. la 1e illustrate sectional constructions of several photosensitive plates which are individually put to use in an embodiment of an electrophotographic copying machine in accordance with the present invention;

FIG. 2 is a sectional side view showing a sectional construction of a transfer sheet of FIGS. 1a 1e;

FIG. 3 is a perspective view showing the appearance of a copying machine in accordance with the invention;

FIG. 4 is a sectional side view showing an embodiment of the present invention;

FIG. 5 is a partial perspective view showing the drive mechanism for driving an original rest carrier and a photosensitive plate in the embodiment of FIG. 4;

FIG. 6 is a partial perspective view showing a device by means of which the transfer sheet is separated from the photosensitive plate upon completion of the transfer thereonto in the embodiment of FIG. 4;

FIG. 7 is a partial section view showing a developing and fixing device in the embodiment of FIG. 4;

FIG. 8 is a diagram of an electrical circuit for the embodiment of FIG. 4; and

FIG. 9 is a sectional side view showing another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Since the photosensitive plate for use in the present invention is quite different from a photosensitive substance which has been put to use in the conventional practical copying machine with respect to the construction and the photosensitive mechanism thereof, it will be first of all described hereinbelow with reference to FIGS. la le.

A photosensitive plate is made up in such a manner that a thin aluminum layer B is evaporated as an electrode onto a flexible film base A consisting of a polyester film with a thickness of 75 u, and laminated thereon is a very thin evaporated non-crystal selenium layer C (in which tellurium less than 7% by weight may be included). Further coated thereon is a painted organic semiconductor layer D consisting of polyvinyl carbasole (PVK), diphenyl trichloride as a plasticizer, and benzene monochloride as a solvent. (The semiconductor layer may include silicon of such a minimal quantity that the electronic photograph image making characteristics will not be affected, and in this case, it is not necessary to include the diphenyl trichloride therein.)

When such a construction as shown in FIG. la is made up, the uppermost PVK layer D will serve as an excellent holder of electric charges as well as a conduit for the passage of positive holes. The thin selenium layer C will generate electric charge carriers by absorbing light, whereas the thin aluminum layer B will prevent the positive holes from migrating into the thin selenium layer C by forming a high rectifying barrier at the interface between the thin aluminum layer B and the thin selenium layer C. Thus, if the surface of the photosensitive plate P is negatively charged and it is thereafter exposed to the light, the positive holes generated in the selenium layer C migrate into the PVK layer D and move towards its surface so as to neutralize'the electric charge on the surface. As a result an electrostatic latent image is formed thereon in response to the exposed light quantity which has an intensified picture image density and good contrast and therefore adaptable to practical use.

When a thin evaporated layer E of a Se-Te alloy is interposed as an intermediate layer between the PVK layer D and the thin selenium layer C as shown in FIG. lb, the thin selenium layer C will lose its light absorptive property and prevents the positive holes from pouring into the aluminum layer B by forming a high rectifying barrier at the interface therebetween. Accordingly, the quantity of tellurium to be mixed with the selenium in the layer E can be desirably adjusted in the range from 10% up to 60% by the weight ratio thereof, to obtain a more highly sensitive photosensi tive plate.

Moreover, in the case where the thin evaporated layer E of a Se-Te alloy in the aforesaid photosensitive plate P is shaped into a grate-like form or a network pattern by means of a high mesh screen such as, for example, a metallic net of 200 400 mesh as shown in FIG. 1c, or a thin Se layer C shaped into a grate-like form or a network pattern in the same way as above is further interposed as an intermediate layer between the PVK layer D and the thin evaporated layer B of a Se-Te alloy as shown in FIG. 1d, a meshwork resolving power is created on account of the difference of the light decaying characteristics between the thin Se layer C and the thin evaporated layer B of a Se-Te alloy caused by the different sensitivities thereof. Thereby obtained is a photosensitive plate having a high resolving power and good half tone reproductivity.

Because, in the aforementioned photosensitive plate P, the Se layer and the Se-Te alloy layer are both composed of a thin film of a thickness less than 1 [.L, and the PVK layer is made of such macromolecular materials as described above, and further the Al layer and the Se evaporated layer are strongly adhered to each other by such a method that the Al layer is first exposed to a glow discharge to have it oxidized by ion bombardment and selenium is thereafter evaporated thereon in a vacuum, the photosensitive plate P can be made up into a flexible sheet which is satisfactorily useful as a photosensitive plate. The flexibility is such that, for instance, even if the photosensitive plate is shaped into a beltlike form and spread between two rollers having respective diameters of substantially 30 mm, and then rotated at a high linear speed of l m per second for a period of 1000 hours, the Al layer and the Se layer are never separated from each other. Additionally, if the flexible film base A in the aforesaid photosensitive plate P is substituted by a metallic plate such as an Al plate as shown in FIG. le, a photosensitive plate is obtained that is inflexible but with such a property that makes it remarkably feasible to ground at the time of its transfer which will be described hereinafter.

Any one of the aforementioned photosensitive plates P may be electrically charged and an electrostatic latent image formed thereon, and thereaftera transfer sheet T is contacted therewith and pressed from its rear face by means of a grounded roller, and then the transfer sheet T is developed by a liquid developer. Transfer sheet T comprises, as shown in FIG. 2, a paper G having a thickness from 25 [L up to y. and treated to be conductive, and a coating H is painted thereon with a high dielectric substance such as, for example, polyethylene, wax, alkyd resin, cellulose acetate, epoxy, or a copolymer of vinyl'chloride and vinyl acetate to a thickness from 2 u up to u. A copy is thereby obtainable which has a picture image better than that of any copy obtainable from Xerographic or an Electrofax type duplicating process of the prior art. Therefore, for instance, in the case where the photosensitive plate P shown in FIG. lb is put to use, if it is charged to a potential higher than 1000V and a picture image of several Lux-sec is projected thereon, thereby obtained on the transfer sheet T is a remarkably sharp, visible image with a high contrast and a high resolving power (more than 50 lines/mm) and without blots in its background. Whereas, in the case where the photosensitive plate P shown in FIG. 10 or d is put to use, if it is charged to a potential from 800V up to IOOOV and a picture image having an intermediate half tone and a brightness between 3 and 10 Lux-sec is projected thereon, thereby obtained on the transfer sheet T is a sharp visible image of which the half tone is fully reproduced with fidelity and the background is completely free of blots.

The copying machine in accordance with the present invention is therefore an appropriate one for permitting such a sheet-like photosensitive plate of a high grade property as aforementioned to put to use therein and an electronic latent image to be formed on the photosensitive plate, and thereafter the electrostatic latent image to be transferred electrostatically onto a transfer sheet.

FIG. 3 and FIG. 4 illustrate the overall construction of an embodiment of the copying machine in accordance with the present invention, wherein, arranged on the top surface of a housing 50 of the copying machine is an original support 51 having an original station 52 fixed thereto and composed of a transparent glass plate. Original support 51 is slidable along the top surface and between two limits defined by the width of the original station 52. An original 0 is placed on the original station 52, and its one face (the underside surface) to be copied is illuminated by a pair of light sources 53 each of which is provided with a reflecting cap and disposed beneath the original station 52 and internally fixed to the housing 50. Applicable as the light source 53 is an iodine lamp shaped into a form to provide a linear light source.

The reference numeral 54 denotes a projecting optical system for producing a mirror image, which optical system 54 comprises a first mirror M for changing the direction of the light reflected on the original surface, a projecting lens L, a second mirror M a third mirror M and a fourth mirror M Juxtaposed along the bottom face of the housing 50 and in parallel with the original station 52 are a cleaner 55 made ofa soft felt or the like for removing dust from the surface of the sheet-like photosensitive plate P, a charging means 56 composed of a corona discharge device, an exposure window 54a of the projecting optical system 54 for producing a mirror image, and a transfer roller 67 of an electrostatic latent image transfer means which will be described hereinlater.

The sheet-like photosensitive plate P is constructed in such a manner, for example, as shown in FIG. 12 in which a base plate composed of an Al plate P of a thickness of 3 mm, and a photosensitive layer P" laminated thereon and consisting of a thin evaporated noncrystal Se layer C and an organic semiconductor paint layer D are together formed as a plate having its photosensitive surface of the size equal to that of the original station 52. The photosensitive plate P is disposed beneath the aforesaid structure and along the bottom face of the housing 50, and both side edges thereof are confined by grounded guide rails so that the photosensitive plate P can be moved in parallel with respect to the original station 52 when it is driven by a pair of

drive rollers

58 and 59.

A transfer material T to be made up into a plurality of final copies has been wound around a roll and loaded into the housing 50. Mounted in sequence for the purpose of conveying the transfer sheet T towards the aforesaid transfer roller 67 are a tension roller 60, a guide roller 61 for confining the transfer position, a pair of guide plates 62, a pair of feeding rollers 63, a cutter 64 for cutting the transfer sheet T to a length corresponding to that of the original 0, a pair of feed-in rollers 65, and a pair of guide plates 66 all of which in combination compose a feeding means 40. The feeding rollers 63 and the feed-in rollers 65 are so constructed as to be driven when the power source circuit of electromagnetic clutches D82 and D51 shown in FIG. 8 is made conductive.

Referring now to FIG. 6, one of the guide plates 66 guiding the transfer sheet T to have it superposed on the photosensitive plate P is curved along a partial surface of the transfer roller 67 so as to cover thereover. A separation device 57 is disposed adjacent to the transfer roller 67 in order to separate an already transferred transfer sheet T from the photosensitive plate P. The separation device 57 comprises a separation guide plate 57a which is pivotally supported by its axle 41 and endowed with a counterclockwise turning tendency by the bias of a coil spring 42 so as to rise and maintain contact with a stop arbor 44 shown in FIG. 4 and FIG. 6. The separation guide plate 57a is provided at the edges of both ends thereof with arcuate rolls 43 so as to slightly protrude from the edges thereof.

A guide means 68 for guiding a separated transfer sheet T towards a developing section is composed of two, i.e., upper and lower,

guide plates

68a and 68b having a clearance therebetween. The lower guide plate 68b is interconnected with the separation guide plate 57a at the time when the separation guide plate 57a is located at its rotated position where it is kept in contact with the stop arbor 44. In order to make it feasible to guide the transfer sheet T with a latent image transferred on its under side face, the lower guide plate 68b is provided with ribs 68' formed thereon and a plurality of small holes 68" punched therein. Accordingly, the transfer sheet T is floated by air blown through the holes 68", and the leading end of the transfer sheet T is thereby capable of being easily transported to sending roller 69.

Arranged on the extension of guide rails 70 is an inserting section of the photosensitive plate P, which section comprises, as shown in FIG. 4, a photosensitive plate holder 72 projecting from the front face of the housing 50, a photosensitive plate guide 71 held by and in the photosensitive plate holder 72, and an arm 71 which is pivotally supported to the housing 50 and reinforcingly supports the photosensitive plate holder 72.

Furthermore, arranged on the original support 51 is a size setting knob 77 with its projection 78 which is fixed to the side face of original support 52 and slidable along a guide bar 76 by manually operating the knob 77 from the outside of the housing 50. By means of the size setting knob 77, the reciprocating strokes of the original support 52 and the photosensitive plate P as well as the length of the transfer sheet T to be cut can be set so as to have them appropriately related with the length of the original 0. The setting operation will be described in detail hereinafter. In addition, there are provided a pair of buffer stops 75 for relieving the shock at the ends of the reciprocating stroke of the original support 52, and a discharge chute 74 for receiving the completed transfer sheet T.

A drive mechanism for reciprocating the photosensitive plate P and the original station 52 is shown in FIG. in which the reference numeral 80 denotes a main motor which is, as seen from the circuit diagram in FIG. 8, a drive source which is rotating while the power source switch SM is kept closed.

A gear 81 is rigidly fixed to the rotating shaft of the main motor 80 and meshes with a gear 83 which is fixed on the left end of a transmitting shaft 82 juxtaposed just thereunder. Mounted on the right end of the transmitting shaft 82 is a gear 84 which is meshed with two

gears

86 and 91. The gear 86 is connected across an electromagnetic clutch 85 by its axle 106, and a gear 87 is fixed to the right end of the axle 106. The gear 91 is connected across an electromagnetic clutch 90 by its axle 107, and two

gears

92 and 88 are fixed to the axle 107 respectively at respective positions thereon as shown in the drawing. The gear 87 is meshed with a gear 89 via the gear 88, and the gear 92 is meshed with a gear 93 which is fixed to a shaft 108 coaxially and integrally with the gear 89.

AS understood from the circuit diamgram in FIG. 8, the electromagnetic clutch 85 is actuated when the power source switch SM and the contact of a relay RYl are both closed, whereas, the electromagnetic clutch 90 is actuated when the power source switch SM and the contact of the relay RYl are both closed and either a microswitch MS6 or MS7 is also closed.

The rotation of the gear 93 and the gear 89 which are integrally fixed together to their common shaft 108 is transmitted to a chain sprocket 94 via the shaft 108, and the rotation of the chain sprocket 94 is transmitted through a chain 95 to the respective sprockets 58a and 59a of both drive

rollers

58 and 59 for driving the photosensitive plate P, and to a sprocket 67a of the transfer roller 67.

A gear 97 which is mounted on the right end of the shaft 108 is connected to the shaft 108 only when an electromagnetic clutch 96 is actuated, and is meshed by gear 98 with a gear 99 which is coaxially fixed to a pulley 100. The electromagnetic clutch 96 is actuated at the time when the power source switch SW, the contact of the relay, either one of the contacts of microswitches MS8 and MSS, and the contact of a relay RY2 are all closed.

Wound on the pulley 100 is operating wire 101 of which one end is fixed to a fitting 51a provided on the support 51 of the original station 52, and moves original support 51 lengthwise in such a manner that the wire 101 is wound up by the pulley 100 in one direction when the pulley 100 is rotated, and it is concurrently released therefrom in the opposite direction.

All of microswitches MS], MS2, MS3, M84, MSS, MS6, MS7, MS8 and M89 arranged in the circuit diagram shown in FIG. 8 are respectively mounted in the housing 50 as shown in FIG. 4 so as to provide the necessary switching functions of the various components of the copying machine.

FIG. 7 illustrates a developing means 38 and a drying and fixing means 39 which are mounted in sequence adjacent to the feed roller 69 for transporting the transfer sheet T.

In a development vessel 25 which is shown in FIG. 7 and contains a circulating pump 9 therein, a reticulated development belt 17 which is revolved around

rollers

2, 3 and 4 in the direction shown by an arrow is spread over the upper portion thereof. The transfer sheet T transported from the feed rollers 69 as described above is placed on the development belt 17 so as to have the electrostatic image surface thereof facing the development belt 17 thereunder, and it is conveyed towards a pair of squeezing rollers 6 and 6'. A developer liquid supply pan 13 which contains a developer liquid chamber 14 for developing an electrostatic latent image transferred onto the underside surface of the transfer sheet T is fixedly disposed immediately beneath and closely to such a linear portion of the reticulated development belt 17 that is located between two rollers 2 and 3. The developer liquid supply pan I3 is provided with a developer liquid supply inlet 11 on one side face thereof, and a developer liquid pool in the development vessel 25 is supplied through a pipe 10 and the inlet 11 into the developer liquid chamber 14 by means of circulating pump 9. The developer liquid discharged through a discharging hole 12 provided on the bottom of the developer liquid chamber 14 is again circulated by means of the pump 9. Disposed at the top portion of the developer liquid supply pan 13 is an electrode plate 15 which is mounted close to the reticulated development belt 17, and a great number of minimal holes or slits have been perforated on the electrode plate 15 for the purpose of supplying developer liquid therethrough onto the latent image surface of the transfer sheet T on the development belt 17. Accordingly, the developer liquid is capable of being supplied uniformly to the underside face of the transfer sheet T through the reticulated development belt 17 and the electrode plate 15 from the developer liquid chamber 14. Additionally, the numeral 16 denotes a guide plate for guiding the transfer sheet T, and the replenishment of developer liquid in the development vessel 25 is carried out by opening a valve 20 provided in the development vessel 25 and thereby supplying developer liquid thereinto through a supply pipe 19 from a storage tank 18. Also provided on a lowest side face of the development vessel 25 is an outlet 24 for discharging the used developer liquid.

The transfer sheet T for which a developing process has been thus finished is transported across a guide roller 5 into a clearance between two squeezing rollers 6 and 6' which are pressed in contact with each other. Any excess developer liquid on the picture image face of the transfer sheet T is removed by moving the sheet in such a way that the peripheral speed of the guide roller 5 is slightly different from the conveying speed of the development belt 17. A cleaner 22 is attachably disposed beneath one squeezing roller 6' which is located on the side where the picture image face of the transfer sheet T comes into contact with the peripheral surface thereof, for the purpose of preventing transference of a picture image to the peripheral surface thereof so as to be again transferred onto the succeeding picture image on the next transfer sheet T. Cleaner 22 contains a wiping substance 23 therein. The squeezing roller 6 located at the opposite side thereof so as to keep in contact with the rear surface of the transfer sheet T is provided with a moisture absorbing roller 7 around which is wound a moisture absorption material which is always kept in contact with the squeezing roller 6. Facing the moisture absorbing roller 7 are a heater 27 which is provided with a reflection helmet 26 to dry-the transfer sheet T, and a slit opening 29 of a transfer sheet preheating device having a transparent guide face 28 thereof. As a modified construction thereof, the squeezing roller 6 may be substituted by having the moisture absorbing roller 7 located thereat so as to have it directly absorb the moisture on the rear face of the transfer sheet T.

The transfer sheet T having passed through the squeezing rollers 6 and 6' is heated and dried by the aforesaid preheating device; thereafter, it is conveyed between two moisture

absorptive rollers

8 and 8 so as to be fully dried out. Arranged beneath the moisture

absorptive rollers

8 and 8 is a drier means of which a drier room 30 is supplied through a duct aperture 31 by means of a fan 35 with either the heated air from light source 53 or the heated air provided from a separate heat source.

The top face of the drier room 30 comprises a guide face 33 for guiding the transfer sheet T, and also the top face is provided at its central portion with an opening 34 through which the moisture absorbing roller 8 located under the opening 34 is inserted into the drier room 30.

The present invention as described above operates as follows. Referring to FIG. 8 and FIG. 4, when the power source switch SM is turned on, the feed rollers 63 and the feed-in rollers 65 are both rotated, as the microswitch MSl has been already closed, by virtue of the electromagnetic clutches D82 and DSl concurrently made operative. Accordingly, the transfer sheet T of which the leading end has been fed from its roll to the rollers 63 is conveyed through the feed rollers 63, the cutter 64 and the feed-in rollers 65 until the leading end opens the microswitch MSl. Thereby the electromagnetic clutches DSl and D82 shown in FIG. 8 are simultaneously de-energized so as to have both pairs of

rollers

63 and 65 stopped. The transfer sheet T is accordingly stopped at once and remains at rest as the microswitch MSl has been opened by the leading end of the transfer sheet T.

The photosensitive plate P is inserted from an inserting slot of the photosensitive plate holder 72 between two guides 71 until its leading end reaches a predetermined position immediately before the microswitch MS6 is tripped by the leading end of the photosensitive plate P.

When it is inserted thereinto too far so that the microswitch MS6 is tripped, as shown in FIG. 8, the operating circuit of the contact of the microswitch MB6 and the electromagnetic clutch 90 are closed, whereby, as understood from the construction in FIG. 5, the

drive rollers

58 and 59 for driving the photosensitive plate P are reversed (assuming that their rotations due to the actuation of the electromagnetic clutch 85 are normal) via the gear 84 which is interlocked with the main motor 80, the gear 91, the electromagnetic clutch 90, the shaft 107, two

gears

92 and 93, the shaft 108, the sprocket 94 and the chain 95. Also the leading end of the photosensitive plate P is thereby pushed back until it is located just before the microswitch M86 and therefore the microswitch M86 is opened so that the photosensitive plate P is stopped.

An original 0 is placed on the original station 52 at the time when the photosensitive plate is positioned as described above. If the length of the original 0 is coincident with the length of the original station 52, the size setting knob 77 is aligned with the utmost position at the right end as shown in FIG. 4, and in all other cases, the knob 77 is aligned with the end portion of the original 0. The preparation for starting a copying operation is accordingly completed.

If a print button P shown in FIG. 3 is first pressed. the relay RYl shown in FIG. 8 is operated so as to force every contact related to the relay to be closed. Consequently, the light source 53 is lit and the electromagnetic clutch is simultaneously actuated, so that the rotation of the gear 84 which is interconnected with the main motor 80 is transmitted, as seen in FIG. 5, through the gear 86, the electromagnetic clutch 85, the shaft 106, three

gears

87, 88 and 89, the shaft I08, the sprocket 94 and the chain 95 to both drive

rollers

58 and 59 which are together rotated in the normal direction so that the photosensitive plate P is conveyed towards the right, as seen in FIG. 4. When the plate P passesthrough the cleaner section 55, contamination on its surface is removed, and when it passes through the charging means 56 which has been concurrently activated, its surface is uniformly charged by a corona discharge unit. It then trips the microswitch MS2 which is thereby shifted 'so as to force the contact of the microswitch MSS, as shown in FIG. 8, to activate the relay RY2 so that the contact of the relay RY2 is switched and is concurrently self-retained. The electromagnetic clutch 96 is simultaneously activated so that, as shown in FIG. 5, the sprocket 94, the shaft 108, the electromagnetic clutch 96 which is also activated, two

gears

97 and 98, and the gear 99 which is integral with the pulley 100 are all interconnected. Consequently, the rotation of the

drive rollers

58 and 59 is transmitted to the pulley 100 so as to allow the original station 52 to begin its movement. The original 0 is thereby projected in sequence by virtue of the light source 53 through the exposure window 54a on the photosensitive plate P which is conveyed across the under face of the exposure window 54a in the direction opposite to that of the original 0. Thereby the photosensitive plate P is sequentially exposed by the exposure light to have an electrostatic latent image of the original 0 formed thereon. As soon as the original station 52 begins its movement as described above, the aftermost end of the original support 51 departs from the microswitch M88 and the contact of the microswitch M88 is accordingly closed.

When the photosensitive plate P trips the microswitch MS3, the microswitch M83 is closed, thereby, the electromagnetic clutches D81 and D82 which were not operable owing to the microswitch MSl being opened previously by having come into contact with the leading end of the transfer sheet T are again activated, the feed roller 63 and the feed-in roller 65 are thereby started to have the transfer sheet T conveyed as before.

Because of the position of the microswitch MS3, the leading end of the transfer sheet T is in the first place conveyed to a position just under the transfer roller 67,

and the photosensitive plate P is some time later conveyed to a position just under the transfer roller 67. Accordingly, an electrostatic latent image on the photosensitive plate P is transferred to the transfer sheet T when both are passing through under the transfer roller 67. Since the leading end of the transfer sheet T which is passing through under the transfer roller 67 precedes the leading end of the photosensitive plate P as described above, the former leading end is directed upward under the guidance of the separation guide plate 57 which is in the upright situation (refer to FIG. 6) and inserted between two

guide plates

68a and 68b for feeding it to the developing section. During that time, the roll 43 is pressed down by the leading end of the photosensitive plate P so as to force the separation guide plate 57 to be turned clockwise against the bias of its spring 42, thereby the photosensitive plate P is capable of linearly advancing, and pushes the microswitch MS7 to have its contact closed.

As the original station 52 is carried leftwards, the juxtaposed microswitches M54 and M89 are simultaneously activated by the projection 78 of the size setting knob 77 fixed to the original support 51, and on account of the actuation of microswitch MS4 the cutter 64 is operated so as to have the transfer sheet T cut into a predetermined size corresponding to the length of the original 0. Because the microswitch M89 is turned on, the relay RY3 is operated so as to have its contact moved, the electromagnetic clutch D82 is thereby deenergized to have the feed roller 63 stopped. When the projection 78 subsequent trips the microswitch MSS to have its contact switched, the relay RY2 is released from its self-retention, and the electromagnetic clutch 96 is de-energized so that the movement of the original station 52 is terminated.

Simultaneously therewith, a timer 105, which is shown in FIG. 8 and has been set to any optional time, commences its operation, and after a definite time, that is, after the trailing end of the photosensitive plate P has passed under the transfer roller 67, it acts on the relay RY4 so as to turn off the microswitch SW2 which is interlocked with the timer 105. Accordingly, the relay RYl is also turned off so as to allow every contact thereof to be switched. Consequently, the movement of the photosensitive plate P is terminated, the charging means 56 is interrupted, and the light source 53 is extinguished, and when the relay contacts are thereafter completely switched, the electromagnetic clutch 90 is activated to have the

drive rollers

58 and 59 reversed, the return motion of the photosensitive plate P is thereby started, and the relay RY2 is concurrently operated by the closed microswitch MS8 so that the electromagnetic clutch 96 is made conductive, and the return motion of the original station 52 is also started. In this case, as clearly understood from FIG. 5, the intermediate gear 88 is excluded from the gearing system as compared with the case of the advance motion of both the original station 52 and the photosensitive plate P. Therefore, the rotation of the gear 89 is not only reversed in the case of the return motion, but also the rotating speed thereof is simultaneously increased due to the gear ratio between both

gears

93 and 92.

When the original station 52 is moving to be fully returned to its initial location, the forward end of the original support 51 acts on the microswitch MS8 to have its contact opened, the original station 52 is thereby stopped. The photosensitive plate P is, when its tail end has passed nearby the microswitch MS6, returned to its initial location owing to the microswitch MS6 which is opened by the tail end thereof.

The transfer sheet T, having an electrostatic latent image transferred thereon, is, as described above, transported from the separation guide plate 5721 between two

guide plates

68a and 68b for carrying it to the developing section, and conveyed by a pair of rollers 69 into the development means 38. Referring to FIG. 7, the transfer sheet T placed on the development belt 17 by the rollers 69 has been provided with an electrostatic latent image transferred on its underside surface, therefore, the transfer sheet T is conveyed by the development belt 17 in such a manner that the electrostatic latent image transferred surfacealone is immersed in the developer liquid passing through the electrode 15 and the development belt 17 disposed adjacent to the top of the developer liquid chamber 14 in which the developer liquid remains full at all times so that the back surface of the transfer sheet is never wetted.

lnterposed between the electrode 15 and the latent image transferred surface of the transfer sheet T is the development belt only, and they are very close to one another, therefore, the development can be speedily carried into effect.

The transfer sheet T developed in the developing means 38 is guided across the guide roller 5 between two squeezing rollers 6 and 6 by which the developer liquid wetting the transfer sheet T is squeezed out. When the transfer sheet T is passed across the guide surface 33 composing the top face of the drier room 30, it is heated by the heater 27 of the pre-drier means and the drier room itself. Moreover, when it is passed between two moisture absorbing rollers 8 and 8', it is fully dried out and then discharged into the discharge chute 74.

According to the present invention, as described hereinabove, a latent image is formed on a photosensitive plate by means of a reciprocating original station 52 and the reciprocating sheet-like photosensitive plate P in a period of their advancing movement. The latent image is transferred to a transfer sheet T from the latent image on the underside surface of the photosensitive plate. Therfore, a photosensitive plate of less area than that of a drum type photosensitive plate in the prior art can be effectively put to use, so that the size of the copying machine itself can be reduced. Moreover, since the surface of the transfer sheet T is extremely close to the electrode of the developing means, it can be speedily developed by being easily immersed in a developer liquid without the contact problems which have been experienced in the prior art. Further, since the back surface of the transfer sheet T is never wetted by the developer liquid, it can be dried in a short time, and a plurality of copies can be therefore completed rapidly. In addition, the photosensitive plate has extremely high sensitivity and high contrast, and it is capable of reproducing intermediate half tones. Accordingly, a picture image obtained on the photosensitive plate is very sharp and representative of the original. Moreover, the photosensitive plate has good durability so that it can be repeatedly used and is easily exchangeable so that it can be easily removed from and reinstalled onto the copying machine. Also the transfer sheet is not provided with a photosensitive surface so that it can be conveniently put in service.

FIG. 9 illustrates another embodiment of the present invention, in which a flexible film is used as the support for the photosensitive substance. Consequently, it is not necessarily required to have the photosensitive substance reciprocated along a straight line, and the photosensitive substance P is capable of being not only guided by a guide plate 114 which enables it to assume an arcuate shape at its retracted position, but also driven by a belt 112 and easily installed into the housing 110 through an opening 111 provided on the top face near the front end thereof. Therefore, the copying machine is advantageous in that it can be designed in a small size as a whole.

However, some modifications of its design are necessary such that the guide plate 115 located in the path of the image making process should be made of a conductive material which is kept in contact with the aluminum layer B sandwiched in the photosensitive substance P, as the photosensitive substance cannot be grounded through the film base. Further, it is necessary to provide the transfer roller 67 with a confronting roller 116 which pinches the photosensitive plate P cooperating with the transfer roller 67.

We claim:

1. An electrophotographic copying machine of the transfer type, comprising:

a carriage mounted to reciprocate along the top surface of the housing of said copying machine and including a transparent plate for supporting an original thereon;

an exposure device including an exposure window and an optical system for projecting a mirror image of said original placed on said transparent plate to said exposure window;

a conveying path along the imaging plane of said optical system and in parallel with said carriage;

a flexible sheet-like photosensitive member movable along said conveying path;

a charging device facing said photosensitive member, a transfer roller for contacting said photosensitive member, said charging device and said roller being mounted along said conveying path on opposite sides of said exposure window;

means for supplying sheet-like transfer material for receiving the image on said photosensitive member;

means for separating said sheet-like material from said photosensitive member;

a driving member for moving said photosensitive member to confront said charging device, said exposure window, said transfer roller and said means for separating, and also to another position where it is separated thereform;

a guide member and a supplying member for feeding said transfer material from said means for susplying onto said photosensitive member and located between said transfer roller and said exposure window;

a member for transporting said separated transfer material towards a development device;

an arcuate guide path disposed on the extension of said conveying path internally in the housing of the copying machine whereby said photosensitive member is thereby curved and guided therealong at the time when said photosensitive member ismoved along said conveying path towards its location away from said charging device, said exposure window and said transfer roller.

2. An electrophotographic copying machine of the transfer type, comprising:

a flexible sheet-like photosensitive member movable along said conveying path;

means for separating said sheet-like material from said photosensitive member;

a driving member for moving, said photosensitive member to confront said charging device, said exposure window, said transfer roller and said means for separating, and also to another position where it is separated therefrom;

a guide member and a supplying member for feeding said transfer material from said means for supplying onto said photosensitive member and located between said transfer roller and said exposure window;

a primary motor source and a primary gear driven thereby;

a first clutch means for transmitting the rotation of said primary gear to a driving shaft rotated in one direction thereby;

a second clutch means for transmitting the rotation of said primary gear to rotate said driving shaft in the reverse direction;

a third clutch means including a driving member connected thereby with said driving shaft for reciprocating said carriage; and

a control circuit for actuating said first, second and third clutch means.

3. An electrophotographic copying machine as in claim 2 further comprising:

a size setting knob for locating said carriage to have it coincident with the width of said original placed on and along said transparent plate;

a first switching means controlled by said size setting knob for cutting said transfer sheets; and

a second switching means for releasing the operation of said third clutch means.

4. An electrophotographic copying machine as in claim 2, further comprising:

a power source switch and a printing switch which are individually operated manually;

a third switching means mounted in said conveying .path and operated by said photosensitive member for actuating said second clutch means to position said photosensitive member at a predetermined said control circuit for operating said first clutch starting position; and means at the time when said printing switch is mana relay switch for opening said control circuit for opually closed.

crating said second clutch means and for closing UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 8619796 Dated January 1, 1975 Inventor(s) susumu ka et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[30] Foreign Application Priority Date December 30, 1970 Japan NO. 122586/70 Signed and sealed this 27th day of May 1.975.

(SEAL) Attest C. MARSHALL DANN RUTH C. MASON V Commissioner of Patents Attesting Officer and Trademarks USCOMM-DC 6037 6-P69 FORM PO-IOSO (10-69) 9 [1.5. GOVERNMENT FRINTING OFFICE: 19! 0-365-33L UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 328619796 D d J n ary 1 1975 Inventor(s) Susumu anaka et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[30] Foreign Application Priority Date December 30, 1970 Japan No. 122586/70 Signed and sealed this 27th day of May 1975.

(SEAL) Attest:

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks FORM PO-IOSO (10-69) UsCOMM-DC scan- U.S. GOVERNMENT FRINTING'OFFICE I969 (IF-366434,

Claims

1. An electrophotographic copying machine of the transfer type, comprising: a carriage mounted to reciprocate along the top surface of the housing of said copying machine and including a transparent plate for supporting an original thereon; an exposure device including an exposure window and an optical system for projecting a mirror image of said original placed on said transparent plate to said exposure window; a conveying path along the imaging plane of said optical system and in parallel with said carriage; a flexible sheet-like photosensitive member movable along said conveying path; a charging device facing said photosensitive member, a transfer roller for contacting said photosensitive member, said charging device and said roller being mounted along said conveying path on opposite sides of said exposure window; means for supplying sheet-like transfer material for receiving the image on said photosensitive member; means for separating said sheet-like material from said photosensitive member; a driving member for moving said photosensitive member to confront said charging device, said exposure window, said transfer roller and said means for separating, and also to another position where it is separated thereform; a guide member and a supplying member for feeding said transfer material from said means for susplying onto said photosensitive member and located between said transfer roller and said exposure window; a member for transporting said separated transfer material towards a development device; an arcuate guide path disposed on the extension of said conveying path internally in the housing of the copying machine whereby said photosensitive member is thereby curved and guided therealong at the time when said photosensitive member is moved along said conveying path towards its location away from said charging device, said exposure window and said transfer roller.

2. An electrophotographic copying machine of the transfer type, comprising: a carriage mounted to reciprocate along the top surface of the housing of said copying machine and including a transparent plate for supporting an original thereon; an exposure device including an exposure window and an optical system for projecting a mirror image of said original placed on said transparent plate to said exposure window; a conveying path along the imaging plane of said optical system and in parallel with said carriage; a flexible sheet-like photosensitive member movable along said conveying path; a charging device facing said photosensitive member, a transfer roller for contacting said photosensitive member, said charging device and said roller being mounted along said conveying path on oppoSite sides of said exposure window; means for supplying sheet-like transfer material for receiving the image on said photosensitive member; means for separating said sheet-like material from said photosensitive member; a driving member for moving said photosensitive member to confront said charging device, said exposure window, said transfer roller and said means for separating, and also to another position where it is separated therefrom; a guide member and a supplying member for feeding said transfer material from said means for supplying onto said photosensitive member and located between said transfer roller and said exposure window; a member for transporting said separated transfer material towards a development device; a primary motor source and a primary gear driven thereby; a first clutch means for transmitting the rotation of said primary gear to a driving shaft rotated in one direction thereby; a second clutch means for transmitting the rotation of said primary gear to rotate said driving shaft in the reverse direction; a third clutch means including a driving member connected thereby with said driving shaft for reciprocating said carriage; and a control circuit for actuating said first, second and third clutch means.

3. An electrophotographic copying machine as in claim 2 further comprising: a size setting knob for locating said carriage to have it coincident with the width of said original placed on and along said transparent plate; a first switching means controlled by said size setting knob for cutting said transfer sheets; and a second switching means for releasing the operation of said third clutch means.

4. An electrophotographic copying machine as in claim 2, further comprising: a power source switch and a printing switch which are individually operated manually; a third switching means mounted in said conveying path and operated by said photosensitive member for actuating said second clutch means to position said photosensitive member at a predetermined starting position; and a relay switch for opening said control circuit for operating said second clutch means and for closing said control circuit for operating said first clutch means at the time when said printing switch is manually closed.