US3462217A

US3462217A - Photoelectrostatic copying machine

Info

Publication number: US3462217A
Application number: US629003A
Authority: US
Inventors: John L Tregay; Kristian L Helland
Original assignee: Multigraphics Inc
Current assignee: AB Dick Co
Priority date: 1964-08-12
Filing date: 1967-04-06
Publication date: 1969-08-19
Anticipated expiration: 1986-08-19
Also published as: GB1118844A

Description

19, 1969- J L, RE ET AL "354625217 PHOTOELECTROSTATIC COPYING MACHINE I Original Filed- Aug- 12. 1964 i a Sheets-Shet 1 Aug. 19, 1969 J. L. TREGAY ETAL 3,452,217

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PHOTOELECTROSTATIC COPYING MACHINE Original Filed Aug. 12, 1964 8 Sheets-Sheet 8 2' 90% 3? l 29 v a I United States Patent Int. Cl. G031) 15/08 US. Cl. 355-14 5 Claims ABSTRACT OF THE DISCLOSURE A photoelectrostatic copying machine in which a moving, charged copy sheet is exposed by a light image derived from the illumination of a synchronized moving original to provide a latent image that is developed by a powder developer. The powder image is then fused. A pair of spaced switches operated in an overlapped relation by the moving copy sheet energize lamps for illuminating the original. An electric dispenser periodically operated by a cam actuated switch adds power to the developer to replace consumed powder. The cam is motor driven in dependence on the running length of copy sheet developed, and the effective length of the cam surface for operating the switch is manually adjusted to change the amount of powder added.

This application is a division of a pending application of John L. Tregay and Kristian L. Helland, Ser. No. 389,037, filed Aug. 12, 1964, now Patent No. 3,398,259.

The present invention relates to automatic copying machines and, more particularly, to a new and improved photoelectrostatic copying machine having new and improved means for controlling the illumination of an original to be copied and the replenishment of developer material.

In automatic copying machines of this type, a copy of a graphic original sheet manually fed into the machine at a feed station is made on a photoconductive copy sheet fed automatically from a supply into the machine in response to feeding an original into the machine. Drive wheels propel the original and the copy sheet in synchronization while the photoconductive copy sheet is electrically charged in the dark and is then selectively exposed at an imaging station in accordance with the light image or pattern produced by illuminating the moving original, the reflected light image from said original being focused by means of an optics assembly onto the charged copy sheet. The exposure of the charged copy sheet produces a latent electrostatic image in accordance with the light pattern dissipating the charge in the illuminated areas and leaving an electrostatic charge in the unexposed areas.

The latent electrostatic image is rendered visible by the application of developer material, such as a granular developer mixture comprising magnetically attractable carrier particles in admixture with a colored thermoplastic resin powder or electroscopic powder in a balanced proportion. In the presence of a magnetic field, this developer mixture forms a brush-like mast to facilitate the application of the electroscopic powder. The electro scopic powder due to the presence of triboelectric forces in the developer mix adheres to the image portions leaving the magnetically attractable carrier particles on the brush.

The resulting powder image is bonded to the copy by passing it through a suitable heating oven maintained at the fusing temperature of the thermoplastic resins but below the char point of the copy paper.

"ice

With the production of each copy there occurs a depletion of the electroscopic powder leaving an increased concentration of carrier particles in the developer mix. This depletion of developer material is not directly dependent on the number of copy sheets developed, unless all of the sheets are of the same size, but varies in dependence on the area of the sheet or its running length. Further, the amount of developer material consumed varies in dependence on the nature of the graphic material to be copied, i.e., less for lines than solid area. This imbalance results in the production of inferior images having low density. As the concentration of magnetically attractable carrier particles increases in the developer mix there is a tendency for the iron particles to print out on the copy sheets. Therefore, one of the important considerations in making quality prints is maintaining a proper ratio of carrier particles to electroscopic resin particles in the developer mix, and it is desirable to provide means which will automatically replenish electroscopic powder in amounts proportional to the quantities removed.

The lamps in the illuminating source that illuminate the graphic original to be copied are frequently relatively high energy devices that tend to generate an appreciable quantity of heat. To avoid damage to the original and to reduce the temperature level in the copying machine, it would be desirable to automatically control energization of the lamps in dependence on the position of the original or the copy material to insure that the lamps would be energized only during the necessary and proper interval in the movement of the original and copy material. Further, it would simplify and reduce the cost of these automatic controls if they could also be used to control the automatic replenishing of the developer material.

Accordingly, one object of the present invention is to provide an improved electroscopic powder dispensing means with an electrical control for automatically replenishing the powder in a developer unit in amounts proportion to the quantities depleted as a result of processing copy sheets through the machine.

Another object is to provide such an automatic dispensing means including means for adjusting the dispensing means to dispense toner powder in time spaced increments contatining different quantities of developer material.

A further object is to provide an electrically operated developer material dispenser controlled by cam actuated switch means in which the cam means are driven by a timing motor automatically operated at spaced time intervals during the operation of a copy machine.

Another object is to provide a cam and switch controlled developer material dispenser in which the part of the path of relative movement between the cam and switch in which the switch is actuated can be manually changed to control the quantity of developer material dispensed in a number of time spaced operations.

Another object is to provide an improved electroscopic powder dispenser with a control for automatically dispensing powder in response to the running length of copy sheet material fed through the machine.

A further object is to provide a copying machine in which switch means actuated by material moving through the machine controls the selective illumination of the original to provide a light image for exposing charged copy material.

Another object is to provide a copying machine in which switch means actuated as original and copy material moves relative to illuminating and exposure stations or areas controls both the illumination of the original material and the periodic operation of a developer material dispensing unit for replacing developer material consumed by the development of images formed on the copy material by the illumination of the original.

A further object of this invention is to provide a copying machine in which a pair of switch means disposed on opposite sides of an area through which material is moved during the generation of an image to be copied are spaced apart a distance less than the length of the material to permit the switch means to be sequentially operated and released to control the energization of original illuminating means.

In accordance with these and many other objects, an embodiment of the invention comprises a photoelectrO- static copying machine including a drive or feeding system for feeding a copy sheet of photoelectrostatic material supplied from a stack thereof past a charging assembly or station at which the sheet receives a uniform electrostatic charge. The drive system moves the charged copy material and the original material to be copied past an exposure station or area and an illuminating area or station, respectively, in synchronism with each other so that lamps at the illuminating station illuminate the original toprovlde a light image which is directed on the copy material to selectively discharge the copy material and form a latent electrostatic image. The latent image is developed at a developer unit or station by the selective deposition of developer material on the copy sheet. This visible image is then fixed or placed in permanent form at a fuser station.

The illumination of the original is controlled by a pair of spaced switches disposed on opposite sides of the exposure station, which switches are operated by the moving copy material to control the energization of the lamps. The switches are spaced apart a distance less than the length of the copy material to permit the lamps to be continuously energized from the operation of the first switch by the leading edge of the copy material to the release of the second switch by the trailing edge of the copy material.

The developer unit supplies electroscopic powder from a suitable container to form the visible image on the copy sheet corresponding to the original. A dispenser including an electric vibrator dispenses electroscopic powder to the developer unit to replace the powder consumed in developing copy sheets. A novel control means including at least one of the switches actuated by the copy sheet energizes the control means to supply powder to the developer unit as a function of the running length of copy sheets fed through the machine. The control means includes a mechanism manually adjustable to vary the amount of powder supplied as required for originals having different image density.

The invention, together with other objects and advantages, will best be understood from considering the following detailed description in conjunction with the drawing in which:

FIG. 1 is a perspective view of a photoelectrostatic automatic copying machine embodying the present invention;

FIG. 2 is an enlarged sectional view of the machine of FIG. 1 taken along a line substantially corresponding to the line 2-2 of FIG. 1;

FIG. 3 is a greatly enlarged, fragmentary, sectional view of a portion of the machine of FIG. 1 taken along a line substantially corresponding to the line 3-3 of FIG. 1 and illustrates particularly the path of travel of an original;

FIG. 4 is an enlarged, fragmentary perspective view, partly broken away, and shows particularly the feeding table of the machine of FIG. 1 with the copy sheet enclosure cover removed;

FIG. 5 is an isometric view of part of the drive system for the machine of FIG. 1;

FIG. 6 is a sectional view of a light source for the machine;

FIG. 7 is a plan view, partly broken, of a removable switching sub-assembly for the copying machine;

FIG. 8 is a schematic circuit diagram of a group of electrical components including several carried by the removable sub-assembly shown in FIG. 7;

FIG. 9 is an enlarged sectional view of a developer and powder dispenser assembly;

FIG. 10 is a sectional view of the developer taken along line 10-10 of FIG. 9;

FIG. 11 is a plan view of a powder dispenser control assembly;

FIG. 12 is an elevational view of the assembly shown in FIG. 11;

FIGS. 13 and 14 are fragmentary sectional views of the control assembly of FIG. -11 taken, respectively, along lines 13*13 and 14-14 of FIG. 11 and showing control cams included in the assembly shown in FIG. 11;

FIG. 15 is a schematic diagram of a circuit for controlling the operation of the machine shown in FIG. 1; and

FIG. 16 is an enlarged sectional view of a fuser conveyor.

Referring now to FIG. 1 of the drawings, an automatic photoelectrostatic copying machine characterized by the features of the invention is designated generally as 20. The machine 20 includes a housing or supporting structure 22 supported by a plurality of downwardly eX- tending legs 24 each having an adjustable foot 26 for leveling the machine 20. The front panel of the machine 20 carries a main switch 34 for controlling the connection of the machine to a suitable source of power. As is shown in FIGS. 1 and 2, the machine 20 is provided with a raised hood 36 including a fan vent 38 cooperating with a fan 4-0 and a fan motor 42 to circulate cooling air in the interior of the machine.

The machine 20 operates in a fully automatic fashion to make one or more copies of an original 30 (FIG, 4). Accordingly, the machine is provided with a feeding table 28 which supports both the original and a stack of copy sheets 32 (FIG. 4) housed within a supply chamber 29 formed by a recess 28a (FIG. 2) in the table covered by an enclosure 50. The table 28 includes a holder and guiding means 44 for storing original sheets 36 to be copied and for guiding each sheet as it is manually fed into the machine where it follows the path of travel illustrated in FIG. 3. The original, which is illuminated by a light unit 46 (FIG. 3) as it travels through the machine 20 is returned to a receving platform 48 conveniently located at the front of the machine.

A copy sheet is automatically passed through the machine from the chamber 29 in synchronism with the original. As is shown in FIG. 2, the copy sheet 32 first passes through a charging assembly 52 where opposite charges are deposited on its opposed surfaces, and through an exposure area 54 where light reflected from the original is focused onto the copy sheet by means of an optics assembly 56.

The exposed copy sheet leaves the exposure area 54, passes through a guide 58 and enters a developing unit 60 where an electroscopic powder, or toner, is deposited on the copy sheet and adheres to those areas corresponding to the dark areas of the original. The direction of travel of the copy sheet is then reversed in a turnaround assembly 62 and is fed through a fuser assembly 64 in which it is heated to render permanent the powder image of the original. The completed copy is then deposited in a copy receiving tray 66 positioned at the front of the machine 20.

The copy sheets 32 may be of any type conventionally used in this art, such as, for example, a paper substrate having one surface treated with a photoconductive material such as zinc oxide dispersed in a resin binder. It is a known characteristic of such copy sheets that they are electrostatically insulating in the dark and capable of accepting a charge which is dissipated by exposing the photoconductive layer to light.

As was indicated above, the storage and supply chamher 29 is formed by a recess 28a disposed between two slabs 28b and 28c at opposed ends of the feeding table 28. A base plate 68 (FIG. 2) secured to the frame of the machine forms the bottom of the chamber and carries a pair of spaced guides 70 which are laterally adjustable within guide slots 68a in the base plate to accommodate copy sheets of various widths. The cover or enclosure 50 (FIG. 1) is hinged on the copy machine 20 and in its closed position extends over the recess 28a to cover the stack of copy sheets 32.

In order to transport a copy sheet 32 from the storage and supply enclosure 50 and to feed it into the machine, there is provided, as shown in FIG. 4, a sheet feeding assembly 74, including a pair of feed rollers 76 resting on top of the stack of copy sheets and mounted upon a rotatable feeder shaft 78. The shaft 78 is mounted between a pair of fixed spaced apart, support plates 79. The opposed ends of the shaft 78 extend through elongated guide slots 79a formed in the plates 79. A lever 80 is provided so that the shaft 78 and the rollers 76 may be manually lifted off of the stack of copy sheets 32 when it is desired to add more sheets or when access to the stack is desired for any other reason. During this operation, the shaft movement is guided and restricted by the slot formations 79a. One end of the feeder shaft 78 carries a sprocket or toothed pulley 82 driven by a toothed belt 84 (FIGS. 4 and 5) to turn the feed rollers 76 and, hence, to advance a copy sheet 32.

As can best be seen in FIG. 5, the toothed belt 84 is driven by means of a sprocket 86 mounted on the end of a clutch shaft 88. Interposed between the sprocket 86 and the clutch shaft 88 is a clutching mechanism 90 of the electrically operated type. When a voltage is applied across suitable terminals (not shown) of the clutch mechanism 90, the clutch shaft 88 is connected to drive the sprocket 86, and the sheet feeding assembly 74 is effective to feed a copy sheet 32. The automatic actuation of the sheet feeding assembly will be described in detail hereinafter in connection with the description of the electrical control circuit of the machine 20. A more detailed description of the structure of a sheet feeding device similar to the sheet feeding assembly 74 may be found in the copending application of Sherell E. Campbell, Ser. No. 291,447, filed June 28, 1963.

A drive motor 92 shown schematically in FIG. 15 drives the various shafts for propelling the copy sheet 32 and the original 30 through the machine. As is shown in FIG. 5, the clutch shaft 88 carries a gear 94 meshed with a second gear 96 mounted upon short shaft 98. The shaft 98 is driven from the drive motor 92 via a drive mechanism including a sprocket 100 and an arrangement of shaft and belts not illustrated After being advanced by the sheet feeding assembly 74, the copy sheet 32, as shown in FIG. 2, passes through a paper guiding construction 102 and between a pair of parallel drive rollers 104 and 106. The copy sheet 32 is advanced by the rollers 104 and 106 through the charging assembly 52 and the exposure area 54 and is then passed to another pair of

parallel rollers

108 and 110. In the charging assembly 52 a set of spaced corona discharge wires 112 and 114 are arranged to deposit opposite charges on the surfaces of the copy sheet 32. In the exposure area 54, those areas of the charged photoconductive surface of the copy sheet 32 corresponding to the light areas of the original 30 are illuminated to dissipate or discharge the electrical charge thereon.

Referring to FIG. 3, it can be seen that an original 30, when manually fed into the machine, passes through a series of paper guides or baffles 116, and between two spaced pairs of driving rollers, one pair of which is identified by reference numerals 118 and 120 while the other pair is identified by reference numerals 122 and 124.

As can best be seen in FIG. 5, the four copy

sheet advancing rollers

104, 106, 108, and 110 and the four original sheet advancing rollers 118, 120, 122, and 124 are mounted in a symmetrical relation in the machine 20.

6 Thus, the rollers 104 and 106 are aligned with the rollers 118 and 120, while the rollers 108 and are aligned with the rollers 122 and 124. Furthermore, the system of gears, sprockets and belts illustrated in FIG. 5 is effective to rotate all of the above mentioned rollers is synchronism. For the purpose of the description the eight rollers and their associated drive elements are designated as a drive sub-assembly 126. As was indicated above, the sub-assembly 126 is driven by the main drive motor 92. As illustrated in FIG. 5 the drive sub-assembly 126 is driven by means of a toothed pulley or sprocket 128 connected via a suitable drive arrangement to the sprocket 100. The drive for the

rollers

104, 106, 108 and 110 may be transmitted to the other four rollers in any suitable manner as, for example, by providing a common shaft 123 supporting the rollers 110 and 124 and utilizing a belt and sprocket drive connecting the rollers 124 and 120. An electrically actuated clutching mechanism 130 shown schematically in FIG. 15 and illustrated in FIG. 5, when energized in a manner described hereinafter, completes the drive from the shaft 123 to the drive assembly 125. An electrically operated brake 132, when energized as described below, holds the original feeding rollers 118 and 120 immobile Without affecting the operation of the copy

sheet feeding shafts

104, 106, 108 and 110. As will be evident from the ensuing description, the brake 132 prevents the original from being advanced until a copy sheet reaches the first pair of rollers 104 and 106 whereupon the brake is automatically released and the clutch 130 energized to permit the original and the copy sheet to advance simultaneously with their leading edges aligned.

An original 30 passes through the pairs of rollers 118, 120 and 122, 124 at exactly the same speed as a copy sheet 32 passes through the pairs of

rollers

104, 106 and 108, 110. As the original 30 passes from the rollers 118, 120 to the rollers 122, 124 it is illuminated by the light unit 46, and, at the same time, the copy sheet, which is passing from the rollers 104, 106 to the

rollers

108, 110 is illuminated by the light reflected from the original and directed to the exposure area 54 by the optics assembly 56. This arrangement of uniformly driven, side by side pairs of rollers for the original and the copy assures that clear, sharp reproductions of the material on the original will appear on the copy sheet at a position exactly corresponding to that occupied by this material on the original sheet.

As the original 30 advances from the first pair of rollers 118, 120 to the second pair 122, 124, it passes over a transparent plate 134 (FIG. 3) through which it is illuminated by means of the lighting assembly 46. In accordance with one feature of the present invention the lighting assembly 46 includes a new improved light source 142 together with means for preventing damage to the original as it is illuminated. The latter means comprises a filter system 138 for preventing passage to the original 30 of infra-red radiation from the source 142 having a. wave length in the range between 7.5 to 15 microns, thereby to prevent radiation in this range from overheating and possibly scorching or burning the original as it passes over the transparent plate 134.

More specifically, the light assembly 46 includes a lamp support 140 for supporting a line type light source 142 in generally parallel relationship with the plane of the copy sheet 30 as it passes over the plate 134. A filter support bracket 144 attached to the lamp support 140 is provided with an aperture 146 to allow light to pass from the light source 142 through the filter system 138 to the transparent plate 134. Flexible clips 148 and 150 are provided on the bracket 144 to clamp or hold in position a set of filter elements 152 and 154 making up the filter system 138. The filters 152 and 154 are of the type which absorb invisible infra-red radiation without reducing the amount of useful visible illumination impinging upon the original 30.

The line light source 142, as can best be seen in FIG. 6, comprises an elongated transparent glass envelope 156 mounted in the lamp support 140 in such manner that light reflected from the support is directed toward the aperture 146. A filament 158 disposed centrally within the envelope 156 has its opposed ends connected to terminal terminal portions 156a to permit electrical connections to be made. In accordance with a feature of the present invention, and in order to illuminate the original 30 uniformly as it passes over the transparent plate 134, the filament 158 is tightly coiled adjacent each of its opposed ends as indicated at 158a, but it loosely coiled at the central portion as indicated at 1581). Since the light intensity imparted by the filament 158 is a function of the filament length, it will be understood that the light in tensity of the filament 158 increases near the tightly coiled ends 158a and decreases near the loosely coiled portion 158b, thereby eliminating difficulties encountered with prior machines in which the central portion of the original has been subjected to more intense light than regions near the side edges.

After the original 30 passes over the transparent plate 134 where it is illuminated by the light assembly 46, it is passed between the rollers 122 and 124 to a turnaround passageway 160 where its direction of travel is reversed by means of paper guides or bafiies 162 and 164. The original is then passed between a pair of rollers 166 and 168 for expelling the original 30 onto the platform 48. The effective length of the receiving area for the original may be extended, if desired, by a sliding tray 49 best shown in FIGS. 1 and 3. The rollers 166 and 168 may be driven in any suitable fashion, as by an idler gear 170 driven by the assembly 126.

The light reflected from the original 30 while it is passing over the plate 134 is directed onto the copy sheet 32 by a series of mirrors and lenses 136 forming part of the optics assembly 56 shown in FIG. 2. Obviously, light is reflected from the white or light areas of the original 30 but is not reflected from the dark or black areas. The areas of the copy sheet 32 corresponding to the light areas of the original are thus exposed and the charge on these areas is dissipated. The charge on the remaining areas of the copy sheet corresponding to the dark areas of the original remains. After the copy sheet 32 has been exposed in the manner described at the exposure area 54, it is passed through the

rollers

108 and 110 and through the paper guiding means 58 to a pair of feed rollers 172 and 174 (FIG. 2) which are driven in a suitable manner by the main drive motor 92 and which serve to deliver the exposed copy sheet 32 to the developer assembly 60.

The developer 60 is best shown in FIGS. 9 and and includes a developer support frame 176 carrying a guide member 178 and a rotatable magnetic brush assembly 180. The guide member 178 is formed of dielectric material and helps direct the copy sheet from the rollers 172 and 174 to the brush assembly 180. A corona discharge wire 182 and a magnetic cleaning assembly 184- are secured to the frame to improve the clarity of the powder image deposited on the copy sheet during its passage through the developer 60. Nap covered rollers 186 and 188 supported by the frame 176 eject the copy sheet from the developer 60 without disturbing the powder image. The developer includes feeding and distributing elements 190 and 192 for distributing electroscopic powdered developer mix or toner 194 along the length of the magnetic brush assembly 180 where it mixes with a. supply of magnetically attractable particles, such as iron particles or the like. The mixture forms into a brushlike configuration on the assembly 180, and the electroscopic particles are deposited on passing copy sheets. The developer assembly 60 is described in greater detail in the copending application of Daniel B. Granzow and John L. Tregay, Ser. No. 307,887, filed Sept. 10, 1963 and assigned to the same assignee as the present invention.

As is best shown in FIG. 9, there is provided a dispenser assembly 196 for selectively dispensing the toner powder 194. The structure and operation of the dispenser assembly 196 is described in detail in the copending commonly assigned, application of Robert L. Gunto, Ser. No. 353, 498, filed Mar. 28, 1964, and will not be further described here, except to note that this assembly includes an electrically operated vibrator 198 for dispensing toner powder only when actuated in a manner to be described in greater detail hereinafter.

It is important that the proper ratio of iron particles and toner be maintained in the developer unit 60. Accordingly, provision must be made to replenish toner that is deposited upon copy sheets as copies are made. If the amount of toner is too small, not only will unsatisfactory copying of the image result, but particles of iron will adhere to the copy sheet. If there is too much toner, the copies will be produced with a dirty or spotted background caused by toner adhering to uncharged areas of the photoconductive layer.

In accordance with a feature of the invention, there is provided a novel control means 200 best shown in FIGS. 11 and 12 for controlling the feeding of toner 194 from the dispenser assembly 196. The control unit 200 automatically maintains the supply of toner mixture at the desired level by replenishing it as it is removed. A novel arrangement is provided to replace toner in an amount proportionah to the running length of copy sheets run throu h the machine without regard to the number of sheets fed. To this end, the control unit 200 includes a switch 202 and a rheostat 204 connected in series with the electrically actuated vibrator 198. Whenever the switch 202 is closed the vibrator 198 is energized to dispense toner to the developer elements and 192. The rheostat 204 is manually adjustable to control the amplitude of vibration of the electrical vibrator 198, thus assuring eflicient operation of the vibrator 198.

In order to support the control unit 200 on the machine 20 there is provided an L-shaped bracket 206 having one leg 206w carrying the rheostat 204. A nut 210 surrounding a shaft 208 clamps the rheostat against the bracket leg 206a. The rheostat 204 is manually adjustable by means of a handle or dial 211 which is exposed to the operator for manual adjustment. In the illustrated embodiment of the invention, for example, the control unit 200 is mounted at the rear of the automatic copying machine 20.

The other leg 206!) of the L-shaped bracket 206 supports a U-shaped bracket 212 carrying a rotary electric motor and gear reduction unit 214 in a position spaced from the leg 206b. The motor unit 214 is held in place by means of suitable fasteners 216 and has an output shaft 218 carrying a cam 220 with a peripheral cam surface 222 shaped as shown in FIG. 14.

The switch 202 includes an actuating arm 224 in the form of a cam follower riding along the cam surface 222. The cam surface 222 gradually increases in radius from a minimum point 222a to a maximum point 22%. When the motor 214 turns the cam 220, a point will be reached where the actuating arm 224 has moved sufiiciently to close the switch 202. The point where this switch closure occurs can be adjusted by altering the position of the switch 202 and its actuating arm 224 relative to the cam surface 222. This is achieved by securing the switch 202 with fasteners 226 to a pivoted switch mounting arm 228. The latter arm includes a first mounting leg 228a which is secured to a spring member 230 by means of a pair of fasteners 232 and the spring member 230 is, in turn, attached to the L-shaped bracket 206 by means of fasteners 234 so that the switch mounting arm 228 may flex or pivot with respect to the fixed, L-shaped bracket 206.

In order to control the position of the switch mounting arm 228, there is provided a manually operable cam element 236 having a peripheral cam surface 238 shaped as shown in FIG. 13. The position of the cam element 236 is adjusted by manually turning a shaft 240 journaled for rotation in the L-shaped mounting bracket 206. The switch mounting arm 228 includes a bent end or cam engaging leg 228b riding on the cam surface 238. A pair of stop surfaces 242 and 244 on the cam limit the rotation of the shaft 240, and between these stop surfaces the cam periphery increases gradually from a minimum radius point 238a to a maximum radius point 238b.

Rotation of the cam 236 thus pivots the switch mounting arm 228 and changes the position of the switch 202 with respect to the cam surface 222. When the leg 228b is in engagement with a small radius portion of the cam surface 238, the arm 224 is moved towards the cam surface 222 and, hence, the switch 202 will be actuated when the arm 224 is engaged by a relatively small radius portion of the cam 220. Conversely, when the leg 228b engages a large radius portion of the cam surface 238, the arm 224 is moved away from the cam surface 222 and, hence, it will not be actuated until it is engaged by a relatively large diameter portion of the cam 220.

Means to be described hereinafter are provided for actuating the motor unit 214 for a period of time depending upon time required for the copy sheet, which moves at a substantially constant speed through the machine, to pass a given point. Thus the length of time that the motor 214 is actuated depends upon the length of copy sheets fed through the machine, rather than only upon the number of copy sheets. Thus, if a long sheet or a continuous web of copy sheet material is fed through the machine, the supply of toner will not become depleted, as would be the case in prior machines.

The position of the switch actuating arm 224 with respect to the cam surface 222 will determine the proportion of time during each rotation of the cam element 220 that the switch 202 is closed. Since the toner replenisher or vibrator 198 is actuated whenever the switch 202 is closed, the amount of toner supplied to the developer elements 190 and 192 may be adjusted for different types of copies by manual rotation of the shaft 240. If originals having a high density of image and requiring a large amount of toner are being copied, the shaft 240 may be rotated until the leg 228b lies near the point 238k on the cam surface 238 so that a relatively large amount of toner is fed. Conversely, if the original has only sparse dark image areas, the operator may turn shaft 240' in the other direction, to decrease the portion for which switch 202 is closed for each rotation of the cam 220.

In a device constructed in accordance with the present invention, paper travels through the machine 20 at the rate of 15 feet per minute, while the motor unit 214 drives the cam 220 through a single revolution each 15 seconds. Thus it will be apparent that when sheets or ordinary 11 inch or 14 inch length are fed through the machine, several sheets will be fed before the cam 220 makes a complete revolution so that toner will not necessarily be dispensed with each passage of a copy sheet. If the machine is used to copy lengthy rolls or a continuous web of material, then cam 220 will make several consecutive revolutions. In either case, the novel control 200 will serve to maintain the supply of toner in the developer 60 at the desired level.

When the copy sheet carrying a loose powder image leaves the developer 60, its direction is reversed by means of the turnaround assembly 62. The assembly 62 includes a motor driven fan unit 248 for blowing air through a duct 250 and a nozzle 252. The stream of air emanating from the nozzle cooperates with a set of guides 254 to feed the copy sheet into the fuser assembly 64. A more detailed description of the apparatus for turning around the copy sheet and feeding it into the fuser 64 may be found in the copen-ding application of Lester R. Rabb, Ser. No. 306,871, filed Sept. 5, 1963 and assigned to the same assignee as the present invention.

The fuser assembly 64 includes a housing 256 enclosing a pair of conveyor belts 258 and 260 (FIG. 2). Disposed within the fuser housing is a heater assembly 262 including

resistance heating elements

264 and 266 supported at their opposed ends by insulated mountings 268. As illustrated schematically in FIG. 15 the resistance heating elements 264 are connected in series, as are the elements 266 and these two groups are provided with

end terminals

278 and 272 and a central terminal 274 so that the two groups can be connected either in series with one another or in parallel or, in the alternative, the group of elements 264 can be used alone. If the groups of

heating elements

264 and 266 are connected in series they act as a 600 watt heater, while if they are connected in parallel they function as a 2300 watt heater for the fuser assembly 64. If the group of resistance elements 264 is used alone, they act as a 900 watt heater.

The conveyors 258 and 260 carry the exposed and developed copy sheet past the heater assembly 262 so that the loosely held powder image on the copy sheet 32 is fused into a permanent image before the sheet is delivered to the platform and extension tray 66. Referring now to FIG. 16, the conveyor 260 comprises an endless belt having a series of continuous, longitudinally extending ridges 276 on the top of which the copy sheet may rest as it is carried through the fuser assembly 64. The ridges 276 permit adequate ventilation around both surfaces of the copy sheet 32 as it is heated in the fuser, and facilitate removal of the copy sheet from the conveyor 260. As is shown in FIG. 2, a plurality of side by side fingers 278 extend into the troughs formed by the ridges 276 to pick up the copy sheet 32 as it leaves the fuser and guide it onto the receiving platform 66 and the extension tray 67.

A switching sub-assembly 280 best shown in FIGS. 4, 7 and 8 is mounted above the feeding table 28 and comprises an elongated housing 282 of generally rectangular cross-section enclosing a plurality of switching and signaling devices including a copy switch 284 and an original switch 286.

A removable cover member 287 (FIGS. 1 and 2) having a pin 287 (a) extending from its underside is adapted to protectively fit over the copy side of the housing 280 with the pin 287 (a) being received into the opening 289.

The original switch 286, as best shown in FIG. 3, comprises a housing 288 containing a double throw switch mechanism adapted to be closed by a switch button 290-. A pivotally mounted lever arm 292 extends outwardly from the housing 282, and is adapted to be pivoted about a rocker shaft 283 by an original sheet 30 as the latter sheet passes between the rollers 118 and 120. The copy switch 284 is similar and includes a switch arm 294 (FIG. 2) which is actuated by a copy sheet 32 when the latter sheet passes between the rollers 104 and 106.

The housing 282 also contains a manually operable feeder switch 296 (FIGS. 4, 7, and 8), a safety switch 298, a switch light 300 and a relay coil 302 which actuates two sets of relay contact 302a and 3021:. The feeder switch 296 is normally left in its closed position during operation of the machine 20. However, should the operator desire to replenish the supply of copy sheets 32, opening of switch 296 will prevent the actuation of the feeder clutch and the feed system 74.

In accordance with the present invention the cover member 287 is removable to facilitate construction and repair of the automatic copying machine 20. When the cover member 287 is removed, the corona discharge wires 112 and 114 of the charging assembly 52 are exposed. Since these discharge wires operate at a high voltage, danger of injury exists when they are exposed. In order to prevent this dangerous condition, the safety switch 298 is arranged so that when the cover member 287 is removed from the machine 20, the switch 298 opens, thus disconnecting the corona discharge wires 112 and 114.

Refering now to FIG. 15, a control circuit 310 is there shown for controlling the operation of the machine 20. The circuit 310 is illustrated as being segregated into three

sub-circuits

312, 314, and 316. The sub-circuit 312 is connected by means of conductors 318 and a plug conl l nector 320 (FIG. 2) to a suitable source of electrical power, for example, a 230 volt, 60 cycle AC source. Sub-circuit 314 is energized via

conductors

322 and 324 from a center tap 326 of a step down auto transformer 328 which supplies 115 volts AC. The sub-circuit 316 operates from a 90 volt DC potential supplied through

conductors

330 and 332 and developed by full wave bridge type rectifier 34.

The operation of the circuit 310 wil now be described, assuming the machine 20 to be initially in its illustrated cool condition, such as would arise from having the machine disconnected overnight. With the plug 320 connected to a suitable outlet, the operator starts the machine 20 by turning on the main switch 34 to energize a coil 336 which closes a set of normally open

main contactors

336a and 336b. It will be noted that each of the conductors 318 is connected to a fuse 338.

Closing of the contactors 336a and 33611 energizes the fan motor 42, which is connected in series with a control rheostat 340 to permit the operator to control the speed of the fan. In addition, the drive motor 92 is energized, as is an exhaust motor 342, which is in series with a suitable heat responsive controlling apparatus 344. Initially, all of the relays are in the condition illustrated in FIG. 15, and, hence, when the

main contactors

336a and 336b are closed the group of series connected fuser heating elements 264 and the group of elements 266 are connected in parallel with each other to generate 2300 watts so that the fuser heater 262 will reach its operating temperature as rapidly as possible. Accordingly, the initial period of time after the machine 20 is energized in its cool condition may be termed a warm-up period, which lasts about 5 or 6 minutes and terminates when the fuser heater reaches operating temperature.

During the warm-up period, the transformer 328 energizes the sub-circuit 314 including a corona power supply 346 which supplies DC power to the upper and lower corona discharge wires 112 and 114. Power supply 346 generates a 12,000 volt DC output, so that the wires 112 and 114 may each be at a potential of either plus or minus 6,000 volts with respect to ground. Additionally, the corona power supply 346 supplies operation voltage for the developer bias corona discharge wire 182. The bias voltage supplied to the wire 182 may be adjusted by means of a manually operated multi-tap control 348, so that the amount of bias may be set to produce clear, sharp copies.

Energization of the sub-circuit 314 also supplies power to the turnaround blower motor and fan 248, as well as to the bridge rectifier 334. It will be observed that, with the copy switch 284 open, the relay coil 302 is not ener gized, so that its contacts 302a and 30211 are in their normal positions illustrated in FIG. 15. With the

switches

284 and 286 both open, neither the copy sheet driving clutch 90 nor the original sheet brake 132 are energized. However, the original sheet driving clutch 130 is energized so that the original sheet feeding rollers 118, 120, 122 and 124 are driven.

After a period of five or six minutes has elapsed, the heat generated by the

fuser heating elements

264 and 266 raises the fuser temperature to the desired operating level. When this occurs a thermally responsive switch 350 moves its contacts 351 from the normally open position shown in FIG. 15 to the closed position, thus energizing a main power relay coil 352, which actuates the

relay contacts

352a, 352b, 352e, 352d, 352a and 352 to move each set to the position opposite from that shown in FIG. 15. It will be seen that a copy light transformer 354 connected to energize a lamp 356 has its primary winding parallel with the coil 352 so that the lamp 356 is energized to signal the operator as soon as the fuser has warmed to operating temperature.

The normally closed contacts 352:: of the main power relay break the circuit to the stepdown transformer 328, so that the sub-circuits 314 and 316 are deenergized.

When the main power relay coil 352 is energized, contacts 35% and 352 interrupt the drive to the main drive motor 92 and the exhaust motor 342. The contacts 3520 and 352d coact with the contacts 352b to realign the

heating elements

264 and 266 6so that both groups are connected in series rather than in parallel, whereby the wattage output drops to 600 watts, which is sufficient to maintain the desired operating temperature. Furthermore, the normally closed contacts 352e, when opened, interrupt the circuits to the turnaround blower motor and fan 248 and to the corona power supply 346. Thus, in accordance with an important feature of the invention, as soon as the fuser reaches operating temperature the machine 20 is automatically placed in a ready condition in which most of the circuit components are deactivated while the machine remains ready to make copies at any time. Furthermore, the lamp 356 is illuminated to indicate this ready condition to the operator.

If it is now desired to make a copy, it is only necessary to depress momentarily a start switch 357 and then to feed an original 30 manually into the machine. Depression of the start switch 357 energizes a slow to release relay 358 which opens its normally closed contacts 358a, thus deenergizing the main power relay 352. The characteristics of the relay 358 are such that it remains actuated for a period of approximately seconds following release of the start switch 357. When the relay 352 is deenergized by operation of the relay 358, the contacts 352a revert to their normally closed position to energize the sub-circuits 314 and 316 and to turn on the switch light 300, thereby indicating to the operator that an original may be fed into the machine. The contacts 352e revert to their normally closed position to energize the motor 248 and the power supply 346, while the

contacts

352b and 352 revert to the positions shown in FIG. 15 to actuate the drive motor 92 and the exhaust motor 342. The contacts 352d return to the position shown in FIG. 15 to interrupt the circuit to the heater elements 266 while the contacts 3520 complete a circuit to the series connected heating elements 264 to generate 900 watts of heat.

When an original 30 is fed into the machine 20, it engages the actuating arm 292 to close the original switch 286 in the manner previously described, thereby breaking the circuit to the original driving clutch 130, and, at the same time, completing a circuit to energize the brake 132. The leading edge of the original sheet is thus held stationary between the inactive rollers 118 and 120 awaiting the feeding of a copy sheet from the stack within the chamber 29. The breaking of the circuit to the clutch prevents driving in opposition to the holding action of the brake 132. When the switch 286 closes, the copy sheet feed clutch 90 is energized and the assembly 74 feeds a single copy sheet 32 from the top of the stack contained in the chamber 29. The copy sheet 32 advances to engage the arm 294, thereby actuating the copy switch 284 in the manner previously described. At this point the leading edges of the

sheets

30 and 32 are exactly aligned and the sheets are oriented side by side within the machine in readiness for advancement at equal speed through the drive assembly 126.

Actuation of the copy switch 284 completes an energizing circuit for a relay 302 having two sets of

contacts

302a and 302b, one set 30% of which interrupts the circuit to the brake 132 while the other set 302a completes a circuit to energize the original driving clutch 130. The original sheet 30 is thus advanced along the plate 134 in synchronization with the movement of the copy sheet through the charging assembly 52 and the exposure area 54. Contacts 30% also break the energizing circuit for the copy sheet feed clutch 90 so that the copy sheet feeding apparatus '74 is dormant until another original is subsequently fed to the rollers 118 and 120. In addition, a counter circuit 360 for registering the number of copies 13 made is actuated when the copy sheet closes the switch 284.

Furthermore, closure of the switch 284 by the copy sheet completes a circuit for energizing a relay coil 362 having two sets of contacts 362a and 362b. The contacts 362b supply power to the toner dispensing control unit 200, so that the output shaft 218 (FIG. 11) of the motor unit 214 begins to rotate. As described above, since motor 214 is actuated while the copy sheet is in contact with the arm 294, toner will be dispensed by the control 200 as a function of copy sheet length fed through the machine 20.

A rectifier 199 connected in series with the vibrator 198 provides half wave rectification to supply a unidirectional voltage of proper polarity to operate the vibrator. In addition, a manually operable push button switch 246 is provided to permit the operator to energize the vibrator independently of the control unit 200 for the purpose of adding additional toner to the developer elements 190 and 192 whenever desired. As was indicated above, the rheostat 204 connected in series with the vibrator may be manipulated to adjust the amplitude of the vibrations. In a machine constructed in accordance with the invention, the output shaft 218 of the motor and gear unit 214 turned at the rate of one revolution each 15 seconds, while paper travelled through the machine at a speed of 15 feet per minute.

The contacts 362a of the relay 362, which is actuated by entry of a copy sheet into the machine, complete a circuit for energizing a relay 364 having two sets of contacts 364a and 364]) located in a circuit for controlling operation of the lamp 142. With the normally open contacts 364a and 364k both closed the lamp 142 is obviously energized. In the illustrated embodiment, the lamp 142 is rated at 1500 watts, and is in series with an eight ampere fuse 366'.

After the copy sheet passes through the second pair of copy

sheet feed rollers

108 and 110, it engages and closes a switch 368 (FIGS. 2 and 15) disposed in advance of the guides 58. This switch maintains the relay 364 energized after the copy sheet releases the switch 284, so that the lamp 142 remains on until the trailing edge of the copy sheet has passed through the exposure area 54. When the trailing edge of the copy sheet moves past the switch 284 the relay 362 is obviously deenergized to break the circuit to the relay 3 64 and also to break the circuit to the control unit 200. With the relay contacts 362a and 362b open, it is apparent that the circuit for energizing the lamp 142 is broken as soon as the trailing edge of the copy sheet moves beyond the switch 368, and, as a consequence, the lamp 142 is deenergized until another copy sheet is subsequently advanced.

It will be recalled that the relay 358 is of the slow to release type and remains energized for a 90 second delay period. The switch light 300, which is oif while the copy switch 284 is closed, is illuminated when the copy sheet passes the switch 284, and it remains illuminated for several seconds thereafter or, more specifically, until the relay 358 becomes deenergized. Deenergization of the relay 358 returns the machine 20 to the ready condition described above. However, another copy may be made as soon as the switch light 300 is illuminated and without waiting for the end of the delay period of the relay 358.

If another original is fed into the machine before the relay 358 is released, it will close the or ginal switch 286, and the above described steps will be repeated. Each time an original is fed the relay 3-58 is reset for a new 90 second release period by current flow through the normally closed contacts 3522, through the contacts 364b when the relay 364 is energized and through the start switch 357 with the latter in its original or non-operated position.

If the supply of copy sheets 32 in the chamber 29 becomes exhausted, a load switch 370 mounted with the chamber 29 as shown in FIG. 4 is automatically closed.

The switch 370 is positioned adjacent one of the plates 79 and includes a switch actuating lever 371 which is depressed when the shaft 78 drops within the guide slots 79a to a predetermined or lowermost position. Closing of the switch 370, as shown in FIG. 15, completes a circuit for actuating a relay 372 having two sets of normally closed

contacts

372a and 372b, one set 372a of which, when opened, interrupts the circuit to the copy sheet feed clutch 90 while the other set 372b, when opened, breaks the circuit to the switch light 300 so that the operator is informed of the shortage of sheets.

Thus, in accordance with the invention, there is provided a novel circuit arrangement whereby the temperature of the fuser or heater is quickly raised and is then held in a ready condition until use. A push button switch conditions the machine to make a single copy automatically of an original fed to the machine, during a 90 second operating cycle at the close of which the machine returns automatically to the ready condition.

Although the present invention has been described with reference to an illustrative embodiment thereof, it should be understood that numerous other modifications and changes will readily occur to those skilled in the art and it is therefore intended by the appended claims to cover all such modifications and changes that will fall within the true spirit and scope of the invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A copying apparatus for making a copy of original material on a length of copy material comprising:

an illuminating station having lamp means for illuminating the original,

an exposure station at which the copy material receives a light image from the illuminating station,

drive means for moving the original material relative to the illuminating station and the copy material relative to the exposure station in a synchronized relation,

first and second switch means disposed adjacent opposite sides of the exposure station and actuated by the moving copy material, the first switch means being operated by the leading edge of the copy material and held operated by the copy material until the copy material operates the second switch means, the second switch means being released by the trailing edge of the copy material,

a first control circuit connected to the lamp means for controlling the energization of the lamps, the first and second switch means being connected in the first control circuit to energize the lamp means in response to the operation of the first switch means and to maintain the energization of the lamp means until the second switch means is released by the trailing edge of the copy material,

a developer unit for receiving the copy material from the exposure station and for applying developer material thereto,

a developer dispensing unit for supplying developer material to the developer unit and including an electrically controlled operating means,

third switch means connected to the electrically controlled operating means for controlling its energization,

rotatable cam means for periodically actuating the third switch means,

a timing motor connected to the cam means for rotating the cam means, and

a second control circuit connected to the timing motor and including at least one of the first and second switch means for controlling the energization of the timing motor to control the selective operation of the developer dispensing unit.

2. A photocopy machine of the photoelectrostatic type for use with an original and copy sheet, the combination comprising:

means for charging the copy sheet,

an illuminating station having a light source,

an exposing station,

means for transporting the original into the illuminating station and the copy sheet into the exposing station with both sheets moving in a synchronized relation,

optical means disposed between the illuminating station and the exposing station so that the image of the original is projected upon the copy sheet at the exposing station,

means for thereafter applying developer material to the exposed copy sheet for developing said sheet, and

control means including a first switch means on one side of the exposing station and second switch means on the opposite side of said exposing station, said first switch means being actuated by the lead edge of the copy sheet to turn said light source on with said second switch means being actuated by the lead edge of said copy sheet to maintain the light source on While said sheet is at the illuminating station and being released as the trailing edge of the copy sheet clears said second switch means to turn oif said light source.

3. An automatic photoelectrostatic copying machine for making a copy of graphic original material on photoconductive copy material comprising:

feeding means for feeding said original material and said copy sheet material in synchornized relation along separate paths, a portion of the path of the copy material providing an exposure area,

an illuminating source for illuminating said original to produce a light image, said illuminating source illuminating the original in an illuminating area along the path of movement of the original,

charging means disposed along the path of the copy material prior to the exposure area for electrostatically charging said copy material,

optical means for focusing the light image from the illuminating area onto said photoconductive copy material in the exposure area and producing an electrostatic image thereon,

developing means for developing said electrostatic image and disposed along the path of the copy material subsequent to the exposure area,

first and second switch means disposed adjacent the path of the copy material on opposite sides of the exposure area, the first switch means being actuated by the copy material as it approaches said one area and the second switch means being operated by the copy material subsequent to the first switch means and being released when the material passes beyond said one area, and

a control circuit connected to the first and second switch means and to the illuminating source for rendering the illuminating source effective in the interval between the actuation of the first switch means and the release of the second switch means.

4. The copying machine set forth in claim 3 in which the control circuit includes a relay having a winding and contacts,

first circuit means including the contacts for controlling the energization of the illuminating source,

second circuit means connecting the first switch means to the winding,

and third circuit means connecting the second switch means to the winding.

5. An automatic photoelectrostatic copying machine for making a copy of a graphic original on a photoconductive copy sheet comprising:

feeding means for feeding said original and said copy sheet in synchronized relation, said feeding means including two spaced sets of rollers for feeding the copy sheet,

a copy sheet exposure area disposed between said spaced sets of rollers,

an illuminating source for illuminating said original to produce a light image,

charging means for electrostatically charging said copy sheet,

optical means for focusing said light image onto said charged photoconductive copy sheet in said exposure area and producing an electrostatic image thereon,

developing means for developing said electrostatic image, 31

first switch means disposed adjacent one of the sets of rollers and operated by the copy sheet,

second switch means disposed adjacent the other sets of rollers and operated by the copy sheet after the first switch means and while the first switch means is held operated by the copy sheet, and

a control circuit connected to the illuminating source and the first and second switch means for rendering the illuminating source effective from the time that the first switch means is operated until the second switch means is released.

References Cited UNITED STATES PATENTS 3,282,177 11/1966 Stanton --1.7 2,478,641 8/1949 Rose 88-24 3,333,566 8/1967 Kent 118-2 3,354,802 11/1967 Doucette 95-1.7

FOREIGN PATENTS 642,101 Belgium.

JOHN M. HORAN, Primary Examiner US. Cl. X.R.