US 3923004 A
A member with a developable image thereon is passed through a development and cleaning station two times; once in one direction and then in the opposite direction. Development of this image with toner particles and wiping and cleaning of the toner particles from the background areas into the image areas and from the member is performed during each pass through the development and cleaning station. A development member and cleaning members, located on each side of the development member in the direction of the path of travel of the image retaining member, perform the above function.
Description (OCR text may contain errors)
United States Patent 1 1 Eichorn, deceased et al.
1 1 DEVELOPMENT AND CLEANING APPARATUS FOR REVERSE PATH MACHINE  Inventors: Roger H. Eichorn, deceased, late of Webster, N.Y.; Lincoln First Bank of Rochester, executor, Rochester, NY.
[731 Assignee: Xerox Corporation, Stamford,
 Filed: Dec. 27, 1973  Appl. No.: 428,975
 US. Cl 118/637; 427/14; 355/3 DD  Int. C1. G03G 13/00  Field of Search 118/637; 117/125;
V  References Cited UNITED STATES PATENTS 3,592,675 7/1971 Tung-nam Cheng ll7/l7.5 3,672,763 6/1972 Levene et al. 118/637 1 Dec. 2, 1975 3,698,926 10/1972 Masayoshi Furuichi ll7/17.5 3,705,767 12/1972 Tamai et a1 118/637 T896011 3/1972 York et a1 355/15 Primary Examiner-Mervin Stein Assistant E.\'aminerSteven Hawkins Attorney, Agenl, 0r Firm-James J. Ralabate; Clarence A. Green; Sheldon F. Raizcs  ABSTRACT A member with a developable image thereon is passed through a development and cleaning station two times; once in one direction and then in the opposite direc tion. Development of this image with toner particles and wiping and cleaning of the toner particles from the background areas into the image areas and from the member is performed during each pass through the development and cleaning station. A development member and cleaning members, located on each side of the development member in the direction of the path of travel of the image retaining member, perform the above function.
6 Claims, 3 Drawing Figures U.S. Patent Dec. 2, 1975 Sheet 1 of3 3,923,004
US. Patent Dec. 2, 1975 Sheet 2 of 3 3,923,004
Sheet 3 of 3 3,923,004
US Patent Dec. 2, 1975 DEVELOPMENT AND CLEANING APPARATUS FOR REVERSE PATH MACHINE DESCRIPTION OF THE INVENTION It is an object of this invention to provide a copying apparatus which has a reverse path image containing member with a mechanism which develops the image and removes particles from the background area into the image area on each pass of the image containing member through a development and cleaning station. This allows for a faster speed of the image containing member past the development and cleaning station with adequate exposure to development.
Other objects of this invention will become apparent from the following description with reference to the drawings wherein:
FIG. 1 is a general schematic view of a copying apparatus embodying the present invention;
FIG. 2 is a partial view of the copying apparatus of FIG. 1 illustrating the position of a web after an image thereon has been developed; and
FIG. 3 is a view of the copying apparatus of FIG. 1
. during transfer of a developed image to a copy medium.
Referring to FIG. 1, a web of heat sensitive material is fed from a supply spool 12 around idler rolls 14, 16,18, and 22 to a take-up spool 24. The web 10 comprises a support with a heat sensitive coating. For example, the support may be an organic film such as a polyester film, cellulose acetate or triacetate film coated with a delayed tack adhesive which is normally hard and non-tacky at room temperature, but which, upon being activated by heat to a tacky condition and subsequently cooled to room temperature, thereafter remains tacky for considerable periods of time varying from at least seconds to several days or more depending upon the particular composition involved. Such delayed tack coatings are well known and can be a mixture of discrete particles of resin, such as indene resin or esterified resin, and discrete particles of crystalline plasticizer, such as diphenyl phthalate or N- cyclohexyl paratoulene sulfonamide. The particles are bound together into the supporting film by a binder, such as styrene-butadiene copolymer. Generally speaking, the crystalline plasticizer component of the mixture is in excess of the resin component.
The supply spool 12 and the take-up spool 24 are connected through a respective slip clutch (not shown) to a reversible motor (not shown). The clutch connection for the supply spool 12 is such that the spool will be positively driven in a counter clockwise direction and slips to allow the spool to rotate in a clockwise direction. The clutch connection for the take-up spool 24 is such that the spool will be positively driven in a clockwise direction and slips to allow the spool to rotate in a counter clockwise direction.
A rotatable cylinder 26 having a highly reflective surface, which may be reversibly driven, is interposed between the idler rolls l6 and 18 and is so arranged that the web 10 is pressed against the idler rolls to form nips 17 and 19. An incandescent lamp 28 is located opposite the cylinder 26 and a reflector 30 is arranged to focus the rays of the lamp 28 onto the cylinder 26 between the idler rolls 16 and 18.
A developing station is provided which comprises a developer housing 32 having a bed of ferromagnetic toner particles 34 therein. The toner particles 34 comprise thermoplastic particles pigmented with carbon black or other radiation absorbing dyes or pigments, and mixed with iron oxide particles.
Two synthetic or fur fibrous cleaning brushes 36 and 38 and a well known magnetic brush 40 are rotatably mounted to the side walls of the housing 32. The upper wall 42 of the housing has three openings 44, 46 and 48 through which a portion of the cleaning brush 36, the magnetic brush 40, and cleaning brush 38 extend, respectively. All of these brushes are arranged to wipe against the web 10 as it passes thereby.
A stationary keeper plate 50 is provided opposite the developer housing 32 and keeps the web 10 in position to be engaged by the cleaning brushes 36 and 38 and the magnetic brush 40.
A stack of copy sheets 52 is located on a paper tray 54. The stack of sheets are urged by a torsion spring 56 against a paper feed roll 58. The paper feed roll 58 drives the uppermost sheet of the stack along a guide 60 to a pair of nip rolls 62 which receive the leading edge of the copy sheet therein. At the proper time, the nip rolls 62 are actuated to drive the copy sheet to the nip 19. A storage recess 64 is provided in the guide 60 to allow the sheet to buckle until the nip rolls 62 are actuated.
An original inlet slot 66 is provided which opens adjacent the nip l7 and an original outlet slot 68 is provided which opens adjacent the nip 19. A copy outlet opening 70 is provided which is also adjacent the nip 17. A microswitch 72 is provided in the original inlet opening 66 which, when actuated, serves to actuate a control mechanism (not shown) which performs the following operation:
Referring to FIG. 1, an original sheet 74 having an image thereon is fed into the inlet slot 66 actuating the switch 72 which sets in motion rotation of the cylinder 26 and the web supply roll 12 and the web take-up roll 24, the cleaning brushes 36 and 38 and the magnetic brush 40 in the direction of the arrows. Also, actuation of this switch 72 activates the lamp 28. The leading edge of the original sheet 74 is fed into the nip 17 and is moved with the web 10 past the lamp 28 and then the original separates from the web and is directed through the outlet opening 68. As the web and original pass the lamp 28, heat is absorbed by the image and transferred to the heat sensitive web 10 to form a tacky image corresponding to the image on the original sheet. As the web 10 and the original 74 pass around the cylinder 26, the sandwich is in tight engagement with the cylinder 26 assuring efficient heat transfer between the image and the heat sensitive layer. The web is transported past cleaning brush 38 which has no effect thereon and then past the magnetic brush 40 which presents toner particles to the web and develops the tacky image thereon. Thereafter, the web is moved past the cleaning brush 36 which wipes toner particles from the background areas into the image areas, thereby cleaning the background areas and adding toner particles to the image areas. During development, the portion of the web passing the cleaning and magnetic brushes takes support on the keeper plate 50 which assures that the toner particles presented by the magnetic brush will engage the web and that the cleaning brushes engage the web. The control system employs a camming mechanism (not shown) which assures that the lamp 28 is illuminated for a sufficient time for the imaging process to be completed and then the lamp is turned off. Referring to FIG. 2, the camming mechanism also assures that a sufficient length of the web corresponding to the length of the sheet to be copied passes at least the cleaning brush 36 prior to stopping with a portion of the leading edge of the developed image being wrapped on the take-up roll 24 as a single layer only to avoid any smudging of the developed image. To illustrate this, the leading edge of the developed image is indicated by reference numeral 76 and the trailing edge is indicated by reference numeral 78.
After the web 10 has stopped, the rotation of the supply roll 12, take-up roll 24, cleaning brushes 36, 38, magnetic brush 40 and the rotation of the cylinder 26 is reversed and the paper feed roll 58 is actuated to move the leading edge of the uppermost sheet of the stack 52 into engagement with the nip rolls 62. The web 10 starts its reverse movement with the former trailing edge 78 now being the leading edge. The cleaning brush 36 engages the web 10 and has very little effect thereon, and then the magnetic brush 40 presents toner particles to the image to develop the same where needed. Thereafter cleaning brush 38 engages the web to perform the same function as performed by the brush 36 when the web 10 passed through the station in the opposite direction. As the leading edge 78 of the image moves toward the nip 19, the nip rolls 62 are actuated at the proper time to move the copy sheet 52 to the nip 19 so that the leading edge of the copy sheet 52 will align with the leading edge 78 of the image just prior thereto. The lamp 28 is illuminated just prior to the leading edge 78 of the developed image and the copy sheet entering the nip 19. The aligned copy sheet and the heat sensitive web are forwarded past the lamp 28 which radiantly heats the toner particles whereby a substantial portion thereof are transfixed (transfer and become fixed) to the copy sheet to provide a reproduction of the original image. This transfixing occurs due to the pressure between the web 10 and the copy sheet 52 which is maintained as they travel around the cylinder 26 and through the nip 17 combined with a corresponding proper temperature. As the copy sheet 52 emerges from the nip 17, the sheet separates from the web 10 and is directed out of the machine through the slot '70. After the trailing edge of the copy sheet 52 has emerged from the nip 17, the lamp 28 is turned off, the nip rolls 62, the cleaning and magnetic brushes stopped, and the rotation of the web supply roll 12 and the take-up roll 24 is reversed to move the used portion of the web 10 to a point where the edge 78 of the last image formed on the web passes just beyond the nip 17 where the web is stopped in position for another copy to be made in the same manner as described above.
Since toner particles are presented to the image on each pass followed by a cleaning brush, the speed of the web may be altered in each direction since the development does not occur in only one pass. Also, the image or development speed need not be dependent upon one another.
The control system and the components thereof for operating the machine in the manner described are all well known and well within the grasp of one having ordinary skill in the art and, therefore, have not been shown.
Since the imaging and developing function of the components of the machine is separate from the image transfer function, the intensity of the lamp 28 and the speed at which the web 10 travels in reverse can be changed from the intensity and speed for the imaging and developing function depending upon for what results the machine is designed. Furthermore, the direc- 5 tion of rotation of the cleaning and magnetic brushes may be as desired for each pass of the web thereacross.
While this machine has been described utilizing an automatic paper feeder, the machine also has utility where the copy sheet 52 is fed by hand into the machine. ln this instance, a pair of nip rolls may be located in the slot 68 which rotate in one direction to withdraw the original from the machine and rotate in the opposite direction at the proper time to pull a copy sheet inserted into the slot 68 to meet the leading edge 78 of the web just prior to the nip 19 for the transfer and fixing of the toner powder image from the web to the copy sheet.
It should further be realized that the concept of this invention is also applicable to developing image bearing members in sheet form rather than in web form as long as means are provided to reverse the path of travel of the sheet to pass through the development and cleaning station in opposite directions.
Rather than transfer the developed image to the copy paper, the developed image may be fused onto the heat sensitive web 10. This may be desired when a series of copies are needed in a specified sequence. In this respect, the surface of the cylinder 26 which will be contacted by the toner particles during the fixing or fusing step must comprise a material to which melted toner particles will not stick. Alternatively, a stack of release sheets could be placed on the paper tray 54 and fed past the lamp 28 in contact with the developed image. In this case, the release sheet will be of a material to which the toner particles will not stick.
What is claimed is:
l. A copier comprising the combination of a member having an imaging surface for carrying latent images; reversible means for moving said member first in one direction and then in the opposite direction along a predetermined path;
development means positioned adjacent said path for applying image developing toner particles to said imaging surface as said member is moving in said one direction and in said opposite direction;
first cleaning means positioned adjacent said path on one side of said development means for removing toner particles from background areas of said imaging surface as said member is moving in said one direction; and
second cleaning means positioned adjacent said path on the other side of said development means for removing toner particles from background areas of said imaging surface as said member is moving in said opposite direction.
2. The copier of claim 1 wherein said first and second cleaning means comprise separate fibrous brushes which are maintained in contact with said imagining surface during movement of said member in said one direction and said opposite direction.
3. The copier of claim 2 wherein said development means is a magnetic brush system having a rotatably driven roller for applying toner laden ferromagnetic developer to said imaging surface.
4. The copier of claim 1 wherein said development means is a magnetic brush system having a rotatably 6. The copier of claim 4 wherein said imaging surface comprises a heat sensitive material for carrying tacky latent images.