US3318213A

US3318213A - Electrophotographic reproducing apparatus

Info

Publication number: US3318213A
Application number: US415071A
Authority: US
Inventors: Charles J Kowalski
Original assignee: Carto Fax Corp
Current assignee: Carto Fax Corp
Priority date: 1964-12-01
Filing date: 1964-12-01
Publication date: 1967-05-09
Anticipated expiration: 1984-05-09

Description

y 9, 1967 c. J. KOWALSKI 3,318,213

ELECTROPHOTOGRAPHIC REPRODUCING APPARATUS Filed Dec. 1, 1964 7 Sheets-Sheet 1 INVENTOR (W/9E1 61? I Kan/A 10 BY KW ,Jalwkm r 4- ATTORNEYS 9, 1967 c. J. KOWALSKI ELECTROPHOTOGRAPHIC REPRODUCING APPARATUS Filed Dec. 1, 1964 '7 Sheets-Sheet 2 INVENTOR CHAeLs's .72 KOWALJK/ ATTORNEYS y 1967 c. 'J. KOWALSKI ELECTROPHOTOGRAPHIC REPRODUCING APPARATUS 7 Sheets-Sheet 3 Filed Dec. 1-, 1964 INVENTOR (HA/9462f a: leow/urle ATTORNEYS y 9, 1967 c. J. KOWALSKI LECTROPHOTOGRAPHIC REPRODUCING APPARATUS '7 Sheets-Sheet 4 Filed Dec. 1, 1964.

ATTORNEYS INVENTOR cum? er .2- ken 41.410 BY 7% y 1967 c. J. KOWALSKI ELECTROPHOTOGRAPHIC HEPRODUCING APPARATUS '7 Sheets-Sheet 5 Filed Dec. l, 1964 f WLL NNN INVENTOR CHAEZEJ J. KOW4LJK/ m wt BY I v 1 54 ATTORNEYS May 9, 1967 c. J. KOWALSKI ELECTROPHOTOGRAPHIC REPRODUCING APPARATUS 7 Sheets-Sheet 6 Filed Dec. 1, 1964 INVENTOR 64,484 4-; 7'. kon/zusz/ ATTORN EYS y 9, 1967 c. J. KOWALSKI ELECTROPHOTOGRAPHIC REPRODUCING APPARATUS '7 Sheets-Sheet 7 Filed Dec. 1, 1964 QQk Q INVENTOR C/IHELEJ I KOH/ALJK/ BY m alaokwv k ATTORNEYS b V\ I wwhb United States Patent Office 3,318,213 Patented May 9, 1967 3,318,213 ELECTROPHOTOGRAPHIC REPRODUCING APPARATUS Charles J. Kowalski, New York, N.Y., assignor to Cartofax, Corporation, New York, N.Y., a corporation of New York Filed Dec. 1, 1964, Ser. No. 415,071 25 Claims. (Cl. 951.7)

This invention relates in general to electrostatic printing and particularly to an improved low-cost photocopy machine.

The electrostatic printing process utilizes a photo-conductive insulating stratum, namely, zinc oxide dispersed in a film forming vehicle and coated on paper. An electrostatic charge is applied to such coated paper and a light image is focused on the surface, discharging those areas where irradiated with light. The remaining areas are still in a charged condition and are developed to form a visible image. This development is rendered by applying a pigmented thermoplastic powder of opposite polarity to that of the charged coated paper to the undischarged areas of the stratum. This developer is referred to in the art as toner. The toner is transferred to the coated paper by means of an iron powder vehicle held together by a magnetic field. The contact between the iron powder and toner produces a triboelectric effect, its magnitude depending on the type of toner used. The toner particles are then wiped across the surface of the coated paper producing a visible image. This image is then fixed onto the surface of the paper by applying heat which causes the thermoplastic to soften and adhere to the paper creating a permanent non-smearable copy.

Since the initial disclosure of the basic concept of electrostatic reproduction, various reproduction machines of both desk top and console design have been developed for commercial use. For the most part, all such machines have utilized numerous rollers for transporting either or both the copy paper and original through the machine. This, in addition to other apparatus which are of great bulk, has made the final unit costly, difficult to maintain, and impractical to move easily as required.

It is, therefore, a principal object of this invention to provide an electrostatic reproduction apparatus which utilizes improved, compact transport and other mechanisms, and a greatly reduced number of moving and operating parts, contained in a unit which is portable and satisfactory for general "copying applications of the type normally encountered in commercial use and which is economical even for the small office.

Another object of this invention is to eliminate the large quantities of heat normally generated by electrostatic reproduction apparatus by energizing the functional components only when required, and, accordingly, the present invention advantageously eliminates any requirement for a cooling system and its consequent bulk and attendant cost.

A further object of this invention is to provide an electrostatic copying machine having mechanisms which apply a calibrated amount of both the toner and the magnetic carrier at a predetermined time as the machine is operated, eliminating fall off of copy quality due to, what is known in the art as, tired iron.

A still further object of this invention is to provide a novel means of transporting the cut sheet of photo-conductive paper which will allow the use of a much lighter base paper than the base paper required for other cut sheet electrostatic machines. This lighter base paper, even with the special coating of photo-conductive material, has a weight and flexibility close to that of ordinary bond paper which is preferred by commercial users due to its ease of handling and the reduced bulk storage of quantities of duplicated materials.

A still further object of the invention is to provide an electrostatic copier which is essentially trouble free and one which can be disassembled for maintenance in a relatively short period of time in the order of a few minutes.

A yet further object of this invention is to provide a means of transporting an original through the viewing mechanism of an electrostatic copying machine which will function perfectly with no harm to the original even though foreign matter such as paper clips or staples are attached to the original.

Another object of this invention is to provide an electrostatic copying machine having an improved magnetic brush which applies toner uniformly upon a photo-conductive sheet bearing a latent electrostatic image and provides a consistent and improved recordation of the image, which brush is, nevertheless, inexpensively formed.

A yet further object of this invention is to improve the method of selecting a single sheet of photoconductive paper from a supply magazine in an electrostatic copier and feeding it into the transport mechanism eliminating the danger of two sheets of photoconductive paper from being fed into the transport web at one time.

For a better understanding of this invention as well as other objects and further features thereof, reference is had to the following detailed description of the invention to be read in connection with the accompanying drawings wherein:

FIG. 1 is a frontal perspective view of the electrophoto graphic device of the invention;

FIG. 2 is a schematic frontal perspective view of the assembly with the cover and framework removed;

FIG. 3 is a right side elevational view with the cover removed;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 1;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 4;

FIG. 6 is a sectional view taken along the line 66 of FIG. 4;

FIG. 7 is an enlarged detail view in section of the web clip and copy paper shortly after the commencement of a typical copying cycle of this invention;

FIG. 8 is a similar detail showing paper being transported on the web while being retained by the clip;

FIG. 9 is a similar detail showing the release of the copy paper following development and fixation of an image thereon;

FIG. 10 is a schematic electrical circuit wiring diagram of the apparatus; and

FIG. 11 is a time sequence chart indicating the operation of the various components and their duration of actuation.

Referring now to the drawings, there is shown particularly in FIG. 1 an electrophotographic apparatus 20 which is adapted for installation with a light-tight or cabinet housing 22. The cabinet, adopting for the most part construction of a conventional manner, has a shelf or platform 24 on the front to aid the operator in guiding the original document 26 into the machine. Directly above the shelf is the photoconductive paper supply magazine 28 which is readily removable by simply sliding it outwards. Directly below the shelf is the exit opening 30 for the original document.

An opening 32 is provided on the front of the top tier of the cabinet to allow for the egress of the completed and developed copy. To the left of the opening, as viewed in FIG. 1, is a light 34 which indicates the operating status of the machine. Directly above lamp 34 3 is on-oif switch 240 and on the right side is exposure control lever 179.

As will be more fully explored, a photoconductive coated sheet 36 is adapted to be carried past the electrophotographic processing stations by a conductive web, herein designated by numeral 38, which is suitably journaled to rotate in a counterclockwise direction, as viewed in FIG. 2.

The processing stations in the path of movement of the Web may be described functionally as follows:

A micro-switch initiator station 40 at which the original document 26, when inserted into the machine 20, activates the necessary operating parts of the machine;

A feed roll station 42, activated by a cam, at which one sheet of photoconductive paper 36 is selected from the top of the paper supply magazine 28 and inserted into a biased clip which closes as the transport web 38 moves forward;

A charging station 44 at which a uniform electrostatic charge is deposited on the photoconductive layer of the copy paper 36;

An exposure station 46 at which a light pattern of the copy to be reproduced is projected onto the electrostatically charged photoconductive sheet causing this charge to be dissipated in the exposed areas thereof and thereby forming a latent electrostatic image;

A developing station 48 at which a developing material consisting of toner particles having a charge opposite to that of the electrostatic image is brushed onto the electrostatically charged photoconductive sheet 36 causing a visible image in the configuration of the original to be reproduced;

A fusing station 50 at which the toner on the electrostatically charged photoconductive sheet 36 is permanently fixed thereon;

A copy removal station 52 at which the copy sheet is transported from the machine by two rubber-faced rollers.

At the initiator station 40, the copying sequence of operation is commenced. As the original document 26 is inserted in the document guide opening 54, the leading edge will actuate switch 56 which is mounted on viewing screen 58 by means of bracket 60. The switch is also positioned above a rubber transport belt 62 which conveys the original document 26 for exposure. The rota tion of the rubber transport belt 62 will cause original 26 to pass over heat resistant glass shield 64 in superimposed relation with screen 58.

The rubber transport belt 62 is driven by motor 66 through mounting drive roller 68 and idler 70. Flanges at both ends of these components prevent the rubber transport belt from walking. Exit guide allows the original document 26 to exit the machine 20 freely onto the desk or other surface on which the machine is placed or into a special container attachable to the machine at an inclined plane to the horizontal. Actuation of switch 56 will close its contact to initiate operation of timing motor 73 by energizing relay 72 causing closure of normally open contacts 72a. Illuminated pilot lamp 34 mounted on cabinet will then be extinguished through the opening of relay contacts 72b.

The operation of timing motor 73 will rotate by means of a ladder chain drive 74 and interconnected sprockets, the cam shaft 76, pull out roll shaft 78, and developer metering shaft 80 in a clockwise direction, as viewed in FIG. 2, and paper feed shaft 82 in a counterclockwise direction. All shafts are suitably journaled to

frames

86 and 88 as, for example, with self aligning bronze bearings and with ball bearings.

The feed roll station 42 will commence operation shortly after the tripping of switch 56. In this connection, an elliptically shaped rubber faced feed roll 90 mounted on shaft 82 will start pushing a sheet 36 of photoconductive paper from supply magazine 28. Upward pressure on paper is maintained on the stack of copy paper by a lever spring 92 which is a spring sheet secured to the magazine 28 and is the width of the copy sheets. Excessive upward travel of the copy paper is prevented by the cover plate 94 of the magazine 28. In a commercial application, a space of about .004 inch is allowed between the cover plate and top edge of the magazine to insure that only one sheet will be indexed at one cycle in the operation of the machine 20. The paper thickness is generally .003 inch and, therefore, no more than one sheet can be forced through the space at one time. The magazine 28 is contained in the machine 20 by plate 96 which, in turn, is supported by

frame sides

86 and 88. Rotation of feed roll shaft 82 will cause the coated paper 36 to travel forward until it is pushed into the presently opened clip 98.

Simultaneous with the feed of sheet 36, cam 100, constituting one of a series of six timing cams, will cause switch 102 mounted on frame plate 104 by means of bracket 106 to activate a non-magnetic stainless steel web 38 and transport belt motor 66. In accordance with a commercial embodiment, the web is about .010 inch thick. A nonmagnetic web (which may be stainless steel, aluminum or copper) is preferred since such material will not attract any iron carrier which may have become magnetized by the action of magnetic induction on such iron.

The belt 33 provides the drive for belt 62 off of motor 66 and, accordingly, synchronization of the travel of the original 26 and copy 36.

Gears

112 and 114 journaled to frame 88 increase the speed and change the direction of rotation of the belt 62 in relation to the web 38. Both web 38 and the transport belt preferably have the same linear speed to prevent the copy from blurring.

At this time, cam 116 will close the contact of 118 thereby keeping timing motor 73 in operation regardless of the length of the original document 26 that served to activate switch 56. As the web 38 moves forward, clip 98 will trip close and securely grip photoconductively coated sheet 36 by its leading edge. This clip 98, also of non-magnetic stainless steel, is adapted to rotate on a pivot 120 under the bias of spring 122 but is held open by trip bar 124 which is mounted to frame 126.

As the coated sheet 36 and the original docoment 26 move in their respective paths, a uniform negative electrostatic charge is deposited on the zinc oxide coated paper at the charging station 44. This is accomplished by means of the transfer of negative ions from the corona charger, the magnitude of which is in the order of 7,000 volts D.C. supplied by power supply 128.

In accordance with a commercial embodiment, the charger assembly at station 44 consists of two tungsten wires suspended between brackets 132 mounted to nylon insulators 134 located on both ends of shield 136. The charger assembly is supported at both ends by frame 8688 and is readily removable for servicing by merely withdrawing the assembly from the frame members which supports it in place.

It should be clearly understood that the web 38 is advantageously grounded by means of two aluminum grounding rollers 138 secured to shaft 140 and journaled to frame 86-88. Grounding the web 38 is essential to insure a uniform charge blanket upon the photoconductive coating of the paper to receive the copy. The web 38 is driven by two rubber covered rollers 142 secured to shaft 144 also journaled to frame 8688. Rubber rollers are preferred as they provide a greater coefi icient of friction thereby eliminating slippage.

It will be noted that the stainless steel non-magnetic web 38 is held in place by rollers mounted on two

shafts

140 and 144. The

shafts

140 and 144 are, in turn, mounted on two metal framepieces which are, in turn, secured to the respective main frames 8688 by a number of screws. The use of an endless web mounted in this fashion permits the removal of the entire copy paper transport mechanism merely by initially loosening the screws and the removal of the fuser to be described. This allows both easy assembly and adjustment and permits repairs and cleaning of the machine to be made in a matter of minutes.

As the electrostatically charged photoconductive paper is drawn past the exposure station 46, it travels over the light shield 146 mounted on optical baflie 148. At this time, lamps 150 will be energized upon activation of switch 152 by cam 154, thereby illuminating the original copy 26 as it passes viewing area. Lamps successfully used in this invention are rated at 500 watts and of iodine quartz, surrounded by reflector 156 and secured to frame 86-88 by means of lampholder frame 158. Two lamps are preferably utilized for uniform distribution of the light. The lamps are positioned on a plane substantially parallel to the viewing area with approximately three inches between them in a successful commercial application. Other sources of light may be used such as suitably rated fluorescent, incandescent, infra-red or ultra-violet light.

Referring now to the optical system of the exposure station 46, a wide angle lens 160' is mounted on the lens frame 162 by flange brackets 164 and the lens frame is securely fastened between the sides of the main frame 8688. A 105 mm. f/3.5 wide angle lens has proven to be more than adequate for this invention. The projected image is bent 90 upward by the front surface mirror 166, which method results in a compact optical fold. Mirror 166 is securely fastened to mirror frame 168 interiorly of the housing 22. Slits rather than holes are preferably provided in the mirror frame 168 for attaching frame to optical housing 170. This permits fine adjustments in focusing between the image object planes to be made relatively quickly and easily in the production of the machine. The image is focused onto the photoconductive electrostatically charged sheet 36 which will, at this time, be attracted to the surface of the web 38 by static attraction. This static attraction is analagous to that of rubbing a hair comb over a woolen cloth and attracting small pieces of paper to the comb. Glass shield 172 fastened to 'baflle 148 by fasteners 174 cooperates in forming a completely enclosed optical housing thus preventing dust from accumulating on the mirror and lens and thereby increasing sharpness of the image. The inside of the optical housing is painted with non-reflecting black paint to eliminate fogging of the copy by scattered incident light.

Of importance is the provision that the intensity of illumination falling on the sensitized sheet 36 may be adjusted to compensate for differences in densities and light reflecting ability of the original document. In this invention, this is effectively controlled by means of an aperture gate 176 fastened to the pivotal exposure control bar 178 an extension 179 of which protrudes from the cabinet, thereby allowing the operator to manually adjust the exposure for producing darker or lighter copies.

The light rays are cast upon the original 26 and then reflected through the lens 160 and bent upward by the mirror 166 to impinge upon those areas of the electrostatically charged photoconductive sheet 36 which corresponds to the non-image areas of the original 26. The light discharges the electrostatic charge in these areas and the charge remains in the areas corresponding to the image areas of the original 26. This charge thus remaining is referred to in the art as the latent image.

The non-magnetic stainless steel web 38 will continue its forward travel and, as the trailing edge of the coated sheet 36 leaves the viewing station 46, the switch 152 activating lamps 150 will de-energize.

As the photoconductive paper 36 is then transported to the developer station 48, another cam 180 activates switch 182 causing developer brush motor 184 to rotate. The developer brush 186 consists of a stationary permanent type bar magnet 188 inside a drum 190 which rotates in the counterclockwise direction, as viewed in FIG.

4, upon rotation of motor 184 in a manner to be described. In this connection, the drum is supported at both ends by

hollow rotor shafts

192 and 194 journaled to frame 86-88 by means of suitable ball bearings to reduce friction. The brush is driven by belt 196 disposed over

pulleys

198 and 200, the latter being keyed to motor 184. Felt wipers 202 are provided to reduce end play and to shield bearings from the abrasive iron carrier.

This drum 190 has 360 V-shaped serrations with the depth of the groove being .010 of an inch. Serrations are provided to carry the magnetic carrier as the drum rotates and to prevent the magnetic carrier from sliding over the drum and thus leaving bare spots on the drum. The stationary permanent bar magnet is placed in a manner whereby the pole face of the bar magnet is located where the drum comes nearest to the photoconductive sheet 36. Accordingly, an extremely effective means is provided for forcing the iron mixed with toner into tufts immediately before such iron comes into contact with the photoconductive sheet 36. These tufts insure an even application of toner, which is interspersed in the iron, to the latent image areas of the photoconductive sheet. This tufting of the mixture of iron and toner has the advantage of forming excellent firm tufts only for the period in the revolution of the drum that the toner is brushed onto the sheet. The tufting thus obtained is equivalent to that normally obtained only by the much more expensive electromagnetic brush developers. The magnetic tuft collapses as the particles of iron mixed with toner pass the pole face and some of the iron and toner is deposited into =bin 204. The advantage of allowing the tufts to collapse is twofold. First, the toner andiron mixture in the bin is then magnetically attracted to those areas of the brush which require additional iron and toner. The second advantage of such tufts is that this collapsing, in combination with the rotation of the brush at about 70 rpm, forces some of the iron and toner to be thrown off the drum into the overflow container 204 by centrifugal force.

Additional toner mixed with iron is applied by the metering shaft 212 journaled to frame 8688. The amount of toner and iron added is determined by the depth of the slot 214 in the shaft 212. This metering shaft makes one rotation every copy cycle, thereby adding a predetermined quantity of developer per copy. This method of continuously adding and removing developer mixture eliminates copy deterioration well known to those in the art as the effect of tired iron. 7 An inexpensive developing station is thusly provided by the combination of the metering device adding fresh toner and iron, the serrated drum, the stationary bar magnet with the pole face near that portion of the drum nearest to the copy being developed, the collapsing of the tuft, redistribution of the iron and toner mixture in the bin, and discarding of excess toner and iron by the centrifugal force of the drum, accordingly, this invention insures consistent, uniformly even, quality copies normally obtainable only .by the use of more expensive electromagnets and complicated metering devices particularly those currently on the market.

The leading edge of the copy 36 will presently approach the fusing station 50 at which time another cam 216 will activate switch 218 thereby energizing the fuser 220. In the preferred embodiment of this invention, this fuser 228 is a quartz infra-red tube with a heating 551% rated at watts per inch. The quartz tube fuser is utilized inasmuch as it will reach its full potential of intensity in a short amount of time. Thus, the fuser 220 need be energized only for the required duration of the passage of the copy 36 past this station 50.

If it is found necessary, particularly when the copying cycle is run continuously for long periods of time, a fan or blower can be incorporated in the cabinet to direct its output or air across the fuser 220 to minimize local heating especially of the metallic web 38.

A heat shield 222 is provided to prevent heat from the fuser from reaching other sections of the machine and thus reducing greatly the problem of excessive accumulation of heat. As the copy 36 passes under the heated fuser, radiant heat will cause the thermoplastic toner to be melted onto the copy paper 36, thereby producing a permanent non-smearable copy.

When the leading edge of the copy paper 36 reaches the copy removal station 52, rubber faced exit rollers 223 will engage the copy paper 36 and cooperate to feed it out through discharge opening 32. Immediately prior to this, however, clip 98 will be opened by contacting pivot bar 224 thereby causing the leading edge of the completed copy sheet 36 to be released. Guides 226 with the front edge parallel to the leading edge of the paper, but slightly under the leading edge, now guide the paper 36 through the opening 32 in the top tier 228 of the cabinet. The copy paper will be transported from the machine by rotation of rubber rollers 223 which travel at the same linear speed as that of the web 38, it being recalled that these rollers are keyed to shaft 78. The rollers 223 continue to rotate to transport the copy sheet from the fusing station 50 and discharge it from the machine.

The web 38 will continue to rotate until it reaches normally closed switch 230 which de-energizes drive motor 66. The contact of this switch is released when its roller 232 meets the rectangular notch 234 on the web 38. This switch 230 insures the exact positioning of the web 38 upon completion of a copy cycle. In addition, this position will not vary from copy to copy; and the clip will remain in the proper open position to receive the next sheet of copy paper when the machine is activated to make another copy.

As the trailing edge of the copy sheet 36 leaves the developer station 48, carn 180 and switch 184 energizing the motor 184 will release its contact preventing any further rotation of the drum -138. Cam 216 and switch 218 activating the fuser 220 will also release its contact as the trailing edge of the copy passes the fusing station 50.

Timing drive motor 73 continues to rotate until the rollers 223 have transported the finished copy 36 from the machine at which time holding cam 118 will deactivate switch 116 thereby stopping the timing drive motor 73. The pilot lamp 34 will then be illuminated indicating the machine is ready for the next reproduction cycle.

FIG. 11 illustrates the sequence of switching of the several components of the machine. It will be noted that the web and transport belt drive motor 66 are not engaged until two seconds after the original is inserted during which time the feed roller 90 selects one sheet of photoconductive paper from the supply magazine 28 and transports it forward into the open clip 98. When a 14-inch original 26 is to be copied, the operator may depress selector switch 240 and insert a magazine with 14-inch-long photoconductive paper 36. The 14-inch selector switch 240 will keep the fuser energized for about three seconds longer by having cam 242 activate switch 244 for the additional interval.

Switch 246 is a double pole single throw toggle switch or any other type of on-olI construction for turning the machine 20 on and off.

To summarize the operation of the copying machine 20 incorporating the teachings of this invention, it will be appreciated that the switch 246 is initially turned on to ready the copying cycle. It will be assumed that the proper size photoconductive coated sheets 36 are in the hopper 28. The original copy to be reproduced is then inserted into the machine 20 through the opening 54 to thereby actuate the switch 56 causing the motor 66 to be energized. The transport belt 62 will now be driven by the motor 66; and the originaldocument 26 will be moved towards the viewing area located between the outer surfaces of the belt and the glass sheet 64.

Substantially simultaneously with the energization of motor 66, the feed roller 90 will remove the uppermost 8 sheet of photoconductive coated paper from the magazine 28. This coated sheet 36 will strike the clip 98 which will no longer be held open by the bar 124. Under these circumstances, the coated paper 36 will be held securely on the web 38.

The coated paper 36 will then be exposed to the charging station 44 at which the high voltage power supply imparts a negative charge to the coated paper.

Upon the closing of switch 56, the timing motor 73 will be energized to commence the operation of the array of timing cams appearing on the shaft '76. As the original document 26 moves into the viewing area, lamps will be activated through the closing of switch 152 by timing cam 154. The movement of the coated sheet 36 is in synchronization with the movement of the original 26 so that the image of the document will be projected by the lens and then reflected by means of mirror 166 onto the coated sheet 36. This causes a discharge in those areas of the coated sheet 36 where there was no corresponding image on the original 26. The original 26 will continue to move and exit the machine through the opening 30. The configuration of the timing cam 154 will be such to assure projection of the entire original document 26 onto the coated paper 36. Following this time interval, the switch 152 will open to de-energize the lamps 150.

The web 38 will continue to transport the coated sheet 36 to the developing station 48. As the coated paper 36 .approaches this station, timing cam will actuate switch 182 to thereby energize motor 184. Accordingly, the magnetic brush 186 will be rotated to cause the toner particles to be deposited on the charged areas of the coated sheet 36 to thereby produce a visible image. Simultaneously with the rotation of the brush, motor 184 will also turn the metering drum 212 for purposes of depositing on the brush a fresh mixture of developer, When the coated sheet 36 is completely developed, the timing cam 180 will open switch 182 to, consequently, deenergize motor 184.

The web 38 continues its rotation and as the leading edge of the copy paper 36 approaches the fusing station 50, timing cam 216 will actuate its switch 218 to energize the fuser 228. As the coated sheet 36 is moved past the energized fuser 228, the thermoplastic toner is softened and adheres to the sheet, thereby producing a non-smearable reproduction of the original. When the trailing edge of the coated sheet 36 clears the fuser 220, the cam 216 will cause its switch 218 to open thereby deenergizing the fuser 220.

As the leading edge of the copy paper 36 approaches the rollers 223, the clip 98 will be shifted to an opened or released position at which the copy paper may now be fed outwardly through the exit opening 32. The web 38 will continue to rotate until an indexing slot or notch 234 therein will open the switch 230 to thereby cause deenergization of motor 66. When this occurs, the machine 20 will be poised and ready for initiation of another copying cycle.

Thus, the numerous aforenoted objects and advantages are most eifectively attained. While the invention has been described with reference to the structure disclosed herein, it is not confined to the details set forth and this application is intended to cover such modifications or changes as may come within the purpose or the scope of the following claims.

I claim:

1. An electrophotographic reproducing apparatus adapted to reproduce documents by electrostatic printing comprising:

a housing;

an original document transport means supported by said housing for receiving an original document to be copied and transport it for exposure and subsequent removal;

a copy paper transport and electrically conductive web supported by said housing for receiving a sheet of copy paper having a photoconductive insulating stratum thereon and transporting it for receiving thereon an image of the original document and then subsequent removal, ground means for electrically grounding said web;

synchronization means for synchronizing the operation of the original document transport means and the copy paper transport web;

a charger supported by said housing adjacent said web for electrostatically charging said paper while being transported by said web, said charge being generated between the charger and the grounded web;

an optical exposure means supported by said housing for directing the image of the original document onto the charged copy paper while both are being transported to discharge those areas of the charged copy paper irradiated with light while maintaining the remaining areas in a charged condition for subsequent developing into a visible image of the original document;

an image developing means supported by said housing operable to develop the image on the copy paper by applying a developing material including a toner of opposite polarity to that of the undischarged areas of the paper;

image fixing means supported by said housing for fixing the visible image on the copy paper;

and copy paper removal means for cooperating in removing the copy paper having the fixed image of the original document thereon.

2. The invention in accordance with claim 1 wherein said original document transport means comprises an endless transport belt driven in synchronization with the movement of said copy paper transport web by said synchronization means, a transparent sheet disposed proximate the outer surface of said belt to receive therebetween the original document and the exposure means directs the image of the original document onto the charged copy paper traveling on the copy paper transport web.

3. The invention in accordance with claim 2 wherein a switch is disposed at the leading end of the transport belt and adapted to be actuated to commence the operation of the electrophotographic reproducing apparatus upon engagement with the original document fed onto the transport belt.

4. The invention in accordance with claim 1 wherein a copy paper magazine is supported by said housing for containing a stack of copy paper, and means for feeding the uppermost sheet of copy paper from the magazine in synchronization with the operation of the original document transport means and copy paper transport web.

5. The invention in accordance with claim 1 wherein said copy paper transport web is made of a sheet of electrically conductive material, said web being in the form of an endless belt and adapted to be rotatably driven in synchronization with the original document transport means by said synchronization means.

6. The invention in accordance with claim 1 wherein said charger includes a pair of tungsten wires, and means for mounting said Wires on said housing such that they are readily removable therefrom.

7. The invention in accordance with claim 1 wherein the optical exposure means includes a lamp assembly for illuminating the original document transported by the original document transport means, a wide angle lens through. which the image of the original document is transmitted, a reflecting means for reflecting the image transmitted by the lens and reflecting it onto the copy paper traveling on the copy paper transport web.

8. The invention in accordance with claim 7 wherein a manually controlled aperture gate is supported by said housing for adjusting the intensity of illumination falling on the copy paper incident to the directing thereon of the image of the original document.

9. The invention in accordance with claim 1 wherein the image developing means comprises a rotatably driven brush having a stationary magnet disposed therein, means for supplying developing material to said brush whereupon said brush is adapted to apply the developing material to the copy paper, and means for permitting the removal of excess developing material that may have fallen off of the brush.

10. The invention in accordance with claim 9 wherein the means for supplying developing material to the brush includes a hopper for containing the developing material located above the brush, said hopper having a discharge opening and a metering drum disposed at the discharge opening of the hopper and being rotatably driven in synchronization with said brush to supply predetermined amounts of developing material to the brush.

11. The invention in accordance with claim 1 wherein said image fixing means includes a fuser having a heating element adapted to apply the requisite intensity of heat in a minimum of time to the copy paper to fix the developed image thereon.

12. The invention in accordance with claim 1 wherein the copy paper removal means includes an exit roller assembly associated with the copy paper transport web to feed the copy paper having the fixed image thereon out of the housing.

13. The invention in accordance with claim 1 wherein timing means are provided for operating the optical exposure means, image developing means, and image fixing means for only a part of the cycle of movement of the copy paper transport web for purposes of minimizing generated heat attributable to the operation of such means.

14. The invention in accordance with claim 13 wherein said timing means includes a timing cam network operable upon introduction of the original document for trans portation by the original document transport means, said timing cam network being operable to actuate and then deactivate said optical exposure means, image developing means and image fixing means at predetermined times during the operation of the transport web.

15. An electrophotographic reproducing apparatus adapted to reproduce documents by electrostatic printing comprlsmg:

a housing;

an original document mounting means for mounting an original document for exposure;

an optical exposure means supported by said housing for directing the image of the original document onto the charged copy paper to discharge those areas of the charged copy paper irradiated with light while maintaining the remaining areas in a charged condition for subsequent developing into a visible image of the original document;

an image fixing means supported by said housing for fixing the visible image on the copy paper;

16. The invention in accordance with claim wherein said copy paper transport web is made of a sheet of electrically conductive material, said web being in the form of an endless belt and adapted to be rotatably driven in synchronization with the original document transport means by said synchronization means.

17. The invention in accordance with claim 15 wherein timing means are provided for operating the optical exposure means, image developing means, and image fixing means for only a part of the cycle of movement of the copy paper transport web for purposes of minimizing generated heat attributable to the operation of such means.

18. The invention in accordance with claim 17 wherein said timing means includes a timing cam network operable upon introduction of the original document for transportation by the original document transport means, said timing cam network being operable to actuate and then deactivate said optical exposure means, image developing means and image fixing means at predetermined times during the operation of the transport web.

19. The invention in accordance with claim 15 wherein the image developing means comprises a rotatably driven brush having a stationary magnet disposed therein, means for supplying developing material to said brush whereupon said brush is adapted to apply the developing material to the copy paper, and means for permitting the removal of excess developing material that may have fallen off of the brush.

20. The invention in accordance with claim 19 wherein the means for supplying developing material to the brush includes a hopper for containing the developing material located above the brush, said hopper having a discharge opening and a metering drum disposed at the discharge opening of the hopper and being rotatably driven in synchronization with said brush to supply predetermined amount of developing material to the brush.

21. The invention in accordance with claim 19 wherein the brush is substantially cylindrical and includes longitudinally extending grooves on its periphery for facilitating the carrying and application of developing material.

22. An electrophotographic reproducing apparatus adapted to reproduce documents by electrostatic printing comprising:

a housing;

a copy paper transport web supported by said housing for receiving a sheet of copy paper having a photoconductive insulating stratum thereon and transporting it for receiving thereon an image of the original document and then subsequent removal, ground means for electrically grounding said web;

a charger supported by said housing adjacent said web for electrostatically charging said paper while being transportedby said web;

a clip being associated with the copy paper transport drum and being adapted to engage and retain on the transport web a sheet of said copy paper, means for biasing said clip into engagement with the outer surface of said web to retain a sheet of copy paper thereon, and means for shifting said clip out of engagement with the outer surface of said web when said copy paper is received by the Web and when the copy paper is to be removed upon the fixation of the image of the original document thereon;

and copy paper removal means for cooperating in removing the copy paper having the fixed image of the original document thereon 23. The invention in accordance with claim 22 wherein said clip is pivotally mounted on the web and a spring is coupled with both said clip and said web to urge the clip into engagement with the outer surface of the web, and at least one post disposed in the path of travel of the clip with web to engage the clip and force it out of engagement with the outer surface of the web about its pivot point against the bias of the spring.

24. An electrophotographic reproducing apparatus adapted to reproduce documents by electrostatic printing comprising:

a housing;

a copy paper transport web supported by said housing for receiving a sheet of copy paper having a photoconductive insulating stratum thereon .and transport ing it for receiving thereon an image of the original document and then subsequent removal, ground means for electrically grounding said web;

a charger supported by said housing adjacent said web for electrostatically charging said paper while being transported by said web;

an optical exposure means supported by said housing for directing the image of the original document onto the charged copy paper to discharge those areas of the charged copy paper irradiated with light while maintaining the remaining areas in a charged condition for subsequent develop-ing into a visible image of the original document;

an image developing means supported by said housing operable to develop the image on the copy paper by applying a developing material including a toner of opposite polarity to that of the undischarged areas of V the paper;

a clip being associated with the copy paper transport drum and being adapted to engage and retain on the transport web a sheet of said copy paper, means for biasmg said clip into engagement with the outer surface of said web to retain a sheet of copy paper thereon, and means for shifting said clip out of engagement with the outer surface of said Web when said copy paper is received by the web and when the copy paper is to be removed upon the fixation of the image of the original document thereon;

and copy paper removal means for cooperating in removing the copy paper having the fixed image of the orlginal document thereon.

25. The invention in accordance with claim 24 wherein said cl1p is pivotally mounted on the web and a spring is coupled with both said clip and said Web to urge the clip into engagement with the outer surface of the web, and at least one post disposed in the path of travel of the clip with Web to engage the clip and force it out of engagement with the outer surface of the web about its pivot point against the bias of the spring.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Kaprelian 951.7 X

Rautbord 8824 Davis 95-1.7 Cerasani 88-24 Okishima 95-1.7

JOHN M. HORAN, Primary Examiner.

Claims

1. AN ELECTROPHOTOGRAPHIC REPRODUCING APPARATUS ADAPTED TO REPRODUCE DOCUMENTS BY ELECTROSTATIC PRINTING COMPRISING: A HOUSING; AN ORIGINAL DOCUMENT TRANSPORT MEANS SUPPORTED BY SAID HOUSING FOR RECEIVING AN ORIGINAL DOCUMENT TO BE COPIED AND TRANSPORT IT FOR EXPOSURE AND SUBSEQUENT REMOVAL; A COPY PAPER TRANSPORT AND ELECTRICALLY CONDUCTIVE WEB SUPPORTED BY SAID HOUSING FOR RECEIVING A SHEET OF COPY PAPER HAVING A PHOTOCONDUCTIVE INSULATING STRATUM THEREON AND TRANSPORTING IT FOR RECEIVING THEREON AN IMAGE OF THE ORIGINAL DOCUMENT AND THEN SUBSEQUENT REMOVAL, GROUND MEANS FOR ELECTRICALLY GROUNDING SAID WEB; SYNCHRONIZATION MEANS FOR SYNCHRONIZING THE OPERATION OF THE ORIGINAL DOCUMENT TRANSPORT MEANS AND THE COPY PAPER TRANSPORT WEB; A CHARGER SUPPORTED BY SAID HOUSING ADJACENT SAID WEB FOR ELECTROSTATICALLY CHARGING SAID PAPER WHILE BEING TRANSPORTED BY SAID WEB, SAID CHARGE BEING GENERATED BETWEEN THE CHARGER AND THE GROUNDED WEB; AN OPTICAL EXPOSURE MEANS SUPPORTED BY SAID HOUSING FOR DIRECTING THE IMAGE OF THE ORIGINAL DOCUMENT ONTO THE CHARGED COPY PAPER WHILE BOTH ARE BEING TRANSPORTED TO DISCHARGE THOSE AREAS OF THE CHARGED COPY PAPER IRRADIATED WITH LIGHT WHILE MAINTAINING THE REMAINING AREAS IN A CHARGED CONDITION FOR SUBSEQUENT DEVELOPING INTO A VISIBLE IMAGE OF THE ORIGINAL DOCUMENT; AN IMAGE DEVELOPING MEANS SUPPORTED BY SAID HOUSING OPERABLE TO DEVELOP THE IMAGE ON THE COPY PAPER BY APPLYING A DEVELOPING MATERIAL INCLUDING A TONER OF OPPOSITE POLARITY TO THAT OF THE UNDISCHARGED AREAS OF THE PAPER; IMAGE FIXING MEANS SUPPORTED BY SAID HOUSING FOR FIXING THE VISIBLE IMAGE ON THE COPY PAPER; AND COPY PAPER REMOVAL MEANS FOR COOPERATING IN REMOVING THE COPY PAPER HAVING THE FIXED IMAGE OF THE ORIGINAL DOCUMENT THEREON.