Apparatus for forming multicolor electrophotographic images through wet-type developing process

Abstract

An apparatus for forming multicolor electrophotographic images through a wet-type developing process has charging, exposure, development, transfer, and cleaning devices disposed around a rotatable latent image carrier. The development device has at least one roller disposed in confronting relation to the latent image carrier, and a development housing in which the roller is rotatably disposed. During the developing process, the development device is supplied with a desired one of liquid developers of different colors stored in respective liquid developer tanks.

What is claimed is: 
     
       1. An apparatus for forming multicolor electrophotographic images through a wet-type developing process, comprising: a latent image carrier .[.rotatable in one direction about its own axis.].;   charging means for charging said latent image carrier;   an optical system for forming an electrostatic latent image on said latent image carrier;   a rotatable development body disposed adjacent to said latent image carrier and rotatable in one direction for supplying a developer to said latent image carrier to visualize a latent image formed on the latent image carrier;   a development housing in which said rotatable development body is rotatably accommodated;   a plurality of developer tanks for storing developers of different colors, respectively;   developer supply means for selectively supplying the developer from one of said developer tanks to said development housing and for returning the developer having developed the image to said one of the developer tanks;   transfer means for transferring the visible image from said latent image carrier to an image transfer sheet;   a sheet feeder device for feeding the image transfer sheet to said latent image carrier;   a first cleaning device for removing the residual developer from said latent image carrier after the visible image has been transferred therefrom; and   a second cleaning device for supplying a cleaning solution to said development housing to clean the development housing and said rotatable development body.   
     
     
       2. An apparatus according to claim 1, wherein said latent image carrier comprises a photosensitive drum. 
     
     
       3. An apparatus according to claim 1, wherein said charging means comprises a charger fixed in the vicinity of the circumferential surface of said latent image carrier. 
     
     
       4. An apparatus according to claim 1, wherein said optical system includes a transparent tape for placing an original document thereon, first through third movable mirrors, a projector lens, a fixed mirror, and a color separation filter device. 
     
     
       5. An apparatus according to claim 4, wherein said color separation filter device is positioned on an optical path between said fixed mirror and said latent image carrier, and comprises a red filter capable of transmitting red and white light, a green filter capable of transmitting green and white light, said color separation filter device being rotatable about its own axis for selectively positioning said red, green, and blue filters on said optical path. 
     
     
       6. An apparatus according to claim 1, wherein said rotatable development body comprises a roller rotatably supported in said dvelopment housing in the vicinity of said latent image carrier. 
     
     
       7. An apparatus according to claim 6, wherein said rotatable development body comprises a plurality of rollers arranged vertically as a first development roller, a second development roller, and a squeeze roller in the order named downwardly. 
     
     
       8. An apparatus according to claim 7, wherein said first and second development rollers are rotatable in the same direction as that of rotation of said latent image carrier and in the direction opposite to that of rotation of said squeeze roller, at positions where said first and second development rollers confront said latent image carrier and said squeeze roller. 
     
     
       9. An apparatus according to claim 8, including a plurality of scrapers held against said first development roller, said second development roller, and said squeeze roller. 
     
     
       10. An apparatus according to claim 9, including a scraper held against the circumferential surface of said second development roller for guiding the developer toward a gap between said latent image carrier and said squeeze roller. 
     
     
       11. An apparatus according to claim 9, including a nozzle disposed between said second development roller and said squeeze roller for supplying the liquid developer to the gap between said latent image carrier and said squeeze roller. 
     
     
       12. An apparatus according to claim 10, wherein said first development roller is dispensed with. 
     
     
       13. An apparatus according to claim 11, wherein said first development roller is dispensed with. 
     
     
       14. An apparatus according to claim 9, wherein said latent image carrier and said second development roller are rotatable at speeds V1, V3, respectively, said speeds V1, V3 meeting the relationship: V1≧V3. 
     
     
       15. An apparatus according to claim 14, wherein the ratio between the speeds of rotation of said latent image carrier and said second development roller ranges from 1:1 to 4:1. 
     
     
       16. An apparatus according to claim 1, wherein said development housing has an inlet port defined in its upper portion for supplying a liquid therethrough into said development housing and an outlet port defined in its lower portion for discharging the liquid therethrough from said development housing, said development housing being disposed in confronting relation to said latent image carrier. 
     
     
       17. An apparatus according to claim 1, wherein said developer tanks are permanently attached to a frame of said apparatus. 
     
     
       18. An apparatus according to claim 17, wherein each of said developer tanks has a toner bottle for storing a color of one color and a solvent tank for storing a toner carrier. 
     
     
       19. An apparatus according to claim 1, wherein at least one of said developer tanks comoprises a disposable tank detachably attached to a frame of said apparatus. 
     
     
       20. An apparatus according to claim 19, wherein said disposable tank has a single chamber for storing a premixed developer composed of a toner of one color and a toner carrier which are mixed at a ratio selected for developing the latent image. 
     
     
       21. An apparatus according to claim 19, wherein said disposable tank has two single chambers, one for storing a premixed developer composed of a toner of one color and a toner carrier which are mixed at a ratio selected for developing the latent image, and the other for storing a toner carrier. 
     
     
       22. An apparatus according to claim 1, wherein said developer supply means comprises a pump disposed in each of said developer tanks, a liquid supply pipe connecting said pump and said development housing to each other, and a liquid retrieval pipe connecting said development housing and said developer tank to each other. 
     
     
       23. An apparatus according to claim 22, including switching means for providing selective communication between said developer tanks and said development device through the liquid retrieval pipes. 
     
     
       24. An apparatus according to claim 23, wherein said switching means comprises a directional control valve. 
     
     
       25. An apparatus according to claim 23, wherein said switching means has a swing pipe angularly movable about an end of said development housing for selective communication with said liquid retrieval pipes. 
     
     
       26. An apparatus according to claim 21, wherein said developer supply means is disposed in each of said chambers. 
     
     
       27. An apparatus according to claim 26, wherein said chambers are divided by a partition, said developer supply means comprises a pump disposed in each of said chambers, a liquid supply pipe connecting said pump and said development housing to each other, and a liquid retrieval pipe connecting said development housing and said developer tank to each other. 
     
     
       28. An apparatus according to claim 27, including switching means for providing selective communication between said developer tanks and one of said chambers, and said development device through the liquid retrieval pipes. 
     
     
       29. An apparatus according to claim 28, wherein said switching means comprises a directional control valve. 
     
     
       30. An apparatus according to claim 28, wherein said switching means has a swing pipe angularly movable about an end of said development housing for selective communication with said liquid retrieval pipes. 
     
     
       31. An apparatus according to claim 1, wherein said transfer means comprises a transfer charger fixed in the vicinity of the circumferential surface of said latent image carrier. 
     
     
       32. An apparatus according to claim 1, wherein said sheet feeder device comprises a sheet cassette, a mechanism for separating and feeding image transfer sheets one by one from said sheet cassette, a pair of feed rollers, a pair of register rollers, a second sheet cassette, and a mechanism for separating and feeding image transfer sheets one by one from said second sheet cassette. 
     
     
       33. An apparatus according to claim 1, wherein said first cleaning device comprises a casing detachably mounted on a frame of said apparatus, a cleaning roller disposed in said casing and mounted by a bracket on said frame, a cleaning blade disposed in said casing and having a free end pressable against said latent image carrier, a squeeze roller held against said cleaning roller, a dispersing plate for dispersing a cleaning solution, and a supply nozzle for supplying the cleaning solution. 
     
     
       34. An apparatus according to claim 33, wherein said bracket is pivotally attached to said frame for angular movement between different positions while and after said latent image carrier is cleaned. 
     
     
       35. An apparatus according to claim 33, wherein said cleaning roller is made of a liquid-absorbing resilient material and rotatably supported on said bracket, said cleaning roller being pressable against said latent image carrier when it is cleaned and separable therefrom after it is cleaned. 
     
     
       36. An apparatus according to claim 35, including a drive mechanism for rotating said cleaning roller. 
     
     
       37. An apparatus according to claim 33, wherein said cleaning blade comprises a resilient plate having its end supported on said bracket. 
     
     
       38. An apparatus according to claim 33, wherein said squeeze roller is pressed against said cleaning roller to elastically deform the same, including a drive mechanism for rotating said squeeze roller. 
     
     
       39. An apparatus according to claim 33, wherein said first cleaning device includes a scraper held against said squeeze roller. 
     
     
       40. An apparatus according to claim 33, wherein said dispersing plate has a pivotally supported end and an opposite free end held by gravity against an upper circumferential surface of said cleaning roller. 
     
     
       41. An apparatus according to claim 40, wherein said opposite free end of the dispersing plate is lower than the pivotally supported end thereof. 
     
     
       42. An apparatus according to claim 33, wherein said supply nozzle is positioned upwardly of said dispersing plate. 
     
     
       43. An apparatus according to claim 42, including a cleaning solution tank for storing a dedicated cleaning solution, said cleaning solution tank having a first pump for supplying the cleaning solution therefrom, one of said developer tanks having a second pump for supplying a black developer therefrom, said supply nozzle being connected through a liquid supply pipe to said first or second pump. 
     
     
       44. An apparatus according to claim 33, wherein said casing has a retrieval port defined in a lower end thereof for retrieving the cleaning solution supplied to said casing. 
     
     
       45. An apparatus according to claim 44, including a cleaning solution tank for storing a dedicated cleaning solution, one of said developer tanks being adapted to store a black developer therein, said retrieval port being connected through a liquid retrieval pipe to said cleaning solution tank or said one of the developer tanks. 
     
     
       46. An apparatus according to claim 45, wherein said cleaning tank has toner processing means. 
     
     
       47. An apparatus according to claim 46, wherein said toner processing means comprises an electrode roller immersible in said cleaning solution for electrically attracting toner in the cleaning solution under a biasing voltage applied to the electrode roller, a scraper held against said electrode roller for scraping t he toner off said electrode roller, and a container for accommodating the toner scraped off said electrode roller. 
     
     
       48. An apparatus according to claim 46, wherein said toner processing means comprises a porous member mounted on the bottom of said cleaning solution tank. 
     
     
       49. An apparatus according to claim 46, wherein said toner processing means comprises a filter member mounted on an outlet end of said liquid retrieval pipe.