Desktop color copier which includes a revolving type developing device

Abstract

A desktop color copier having a size which allows the copier to be placed on a stand when the copier is used. The desktop color copier includes a photoconductive drum for sequentially forming toner images of respective colors thereon, a charger for charging the photoconductive drum, an exposure device for exposing the charged photoconductive drum, a revolving type developing device for forming color toner images on the photoconductive drum, an image transferring devices which includes an intermediate transfer belt to which the color toner images are sequentially transferred one on top of the other, and a fixing device for fixing the color toner images on a sheet of paper. The desktop color copier includes a single paper feed tray which is located under the transferring device.

What is claimed as new and desired to be secured by Letters Patent of the United States is:  
     
       1. A color image forming apparatus for forming a toner image on a sheet of paper, comprising: 
       an image carrier for substantially forming toner images of respective colors thereon;  
       a charger for charging said image carrier;  
       an exposure device for exposing said image carrier which has been charged and forming electrostatic latent images of respective colors on said image carrier;  
       a revolving type developing device which is rotatively supported in said color image forming apparatus, including a plurality of color developing devices, each of which includes a developing unit for developing a toner image on said image carrier when said developing unit faces said image carrier and a toner supply unit for supplying toner to said developing unit, wherein an external shape of said revolving type developing device is a cylinder;  
       an intermediate transfer belt to which said toner images are sequentially transferred on top of previously transferred toner images;  
       a primary transferring charger for sequentially transferring said toner images from said image carrier to said intermediate transfer belt to form a composite toner image on said intermediate transfer belt;  
       at least one paper feed tray for storing sheets of paper and feeding the sheets of paper one at a time;  
       a secondary image transferring charger for transferring said composite toner image from said intermediate transfer belt to one of the sheets of paper; and  
       a fixing device for fixing said toner image on said sheet of paper,  
       wherein a length of said intermediate transfer belt is greater than a circumference of said image carrier.  
     
     
       2. A color image forming apparatus as claimed in  claim 1 , wherein said image forming apparatus is a color copier. 
     
     
       3. A color image forming apparatus as claimed in  claim 2 , wherein said at least one paper feed tray is a single paper feed tray. 
     
     
       4. A color image forming apparatus as claimed in  claim 3 , wherein said paper feed tray is located under said image carrier, said revolving type developing device, said intermediate transfer belt, said primary transfer charger, said secondary transfer charger, and said fixing device. 
     
     
       5. A color image forming apparatus as claimed in  claim 2 , wherein said color image forming apparatus is a digital color copier. 
     
     
       6. A color image forming apparatus as claimed in  claim 1 , wherein said image carrier is a photoconductive drum having a diameter from 30 mm to 90 mm. 
     
     
       7. A color image forming apparatus as claimed in  claim 6 , wherein a length of said intermediate transfer belt with respect to the moving direction of said belt is an integral number of times a circumference of said photoconductive drum. 
     
     
       8. A color image forming apparatus as claimed in  claim 7 , further comprising a stand for supporting the image forming apparatus, said stand having a plurality of paper feed trays from which said one of the sheets of paper is fed, wherein said at least one paper feed tray is a duplex paper feed tray. 
     
     
       9. A color image forming apparatus as claimed in  claim 1 , wherein the revolving type developing device includes a cylindrical black toner cartridge disposed along an axis of rotation of the revolving type developing device. 
     
     
       10. A color image forming apparatus as claimed in  claim 9 , wherein said plurality of color developing devices include cyan, magenta, and yellow developing devices, each having toner cartridges which rotate with the revolving type developing device. 
     
     
       11. A color image forming apparatus as claimed in  claim 10 , wherein the black toner cartridge has a door which opens and closes by a force due to gravity as the revolving type developing device revolves such that tone is permitted to flow from the black toner cartridge when the door is open and toner is not permitted to flow between the black toner cartridge and a corresponding development unit of the developing device when the door is closed. 
     
     
       12. A color image forming apparatus according to  claim 1 , further comprising: 
       a stand for supporting the color image forming apparatus.  
     
     
       13. A color image forming apparatus according to  claim 12 , wherein a height of the color image forming apparatus when being supported by the stand is less than or equal to 950 mm. 
     
     
       14. A color image forming apparatus according to  claim 12 , wherein a height of the stand is at least 380 mm. 
     
     
       15. A color image forming apparatus according to  claim 1 , wherein said revolving type development device is located within 10 mm from said fixing device. 
     
     
       16. An apparatus according to  claim 1 , further comprising: 
       a fan which creates an air flow between said revolving type developing device and said fixing device for cooling said revolving type developing device.  
     
     
       17. An apparatus according to  claim 1 , wherein: 
       the length of said intermediate transfer belt is at least twice as great as the circumference of said image carrier.  
     
     
       18. An apparatus according to  claim 1 , wherein: 
       the length of said intermediate transfer belt is at least five times as great as the circumference of said image carrier.  
     
     
       19. A color image forming apparatus for forming a toner image on a sheet of paper, comprising: 
       an image carrier for sequentially forming toner images of respective colors thereon;  
       a charger for charging said image carrier;  
       an exposure device for exposing said image carrier which has been charged and forming electrostic latent images of respective colors on said image carrier;  
       a revolving type developing device which is rotatively supported in said color image forming apparatus, including a plurality of color developing devices, each of which includes a developing unit for developing a developing a toner image on said image carrier when said developing unit faces said image carrier;  
       intermediate transfer belt to which said toner images are sequentially transferred on top of previously transferred toner images;  
       primary transferring charger for sequentially transferring said toner images from said image carrier to said intermediate transfer belt to form a composite toner image on said intermediate transfer belt;  
       at least one paper feed tray for storing sheets of paper and feeding the sheets of paper one at a time;  
       a secondary image transferring charger for transferring said composite toner image from said intermediate transfer belt to one of the sheets of paper; and  
       a fixing device for fixing said toner image on said sheet of paper,  
       wherein a length of said intermediate transfer belt is greater than a circumference of said image carrier.  
     
     
       20. A color image forming apparatus as claimed in  claim 19 , wherein said image forming apparatus is a color copier. 
     
     
       21. A color image forming apparatus as claimed in  claim 20 , wherein said at least one paper feed tray is a single paper feed tray. 
     
     
       22. A color image forming apparatus as claimed in  claim 21 , wherein said paper feed tray is located under said image carrier, said revolving type developing device, said intermediate transfer belt, said primary transfer charger, said secondary transfer charger, said fixing device. 
     
     
       23. A color image forming apparatus as claimed in  claim 20 , wherein said color image forming apparatus is a digital color copier. 
     
     
       24. A color image forming apparatus as claimed in  claim 19 , wherein said image carrier is a photoconductive drum having a diameter from 30 mm to 90 mm. 
     
     
       25. A color image forming apparatus as claimed in  claim 24 , wherein a length of said intermediate transfer belt with respect to the moving direction of said belt is an integral number of times a circumference of said photoconductive drum. 
     
     
       26. A color image forming apparatus as claimed in  claim 25 , further comprising a stand for supporting the image forming apparatus, said stand having a plurality of paper feed trays from which said one of the sheets of paper is fed, wherein said at least one paper feed tray is a duplex paper feed tray. 
     
     
       27. A color image forming apparatus as claimed in  claim 19 , wherein said revolving type developing device is located within 10 mm from said fixing device. 
     
     
       28. A color image forming apparatus as claimed in  claim 27 , further comprising: 
       fans which create an air flow between said revolving type developing device and said fixing device for cooling said revolving type developing device.  
     
     
       29. A color image forming apparatus as claimed in  claim 19 , wherein the revolving type developing device includes a cylindrical black toner cartridge disposed along an axis of rotation of the revolving type developing device. 
     
     
       30. A color image forming apparatus as claimed in  claim 29 , wherein said plurality of color developing devices include cyan, magenta, and yellow developing devices, each having toner cartridges which rotate with the revolving type developing device. 
     
     
       31. A color image forming apparatus as claimed in  claim 30 , wherein the black toner cartridge has a door which opens and closes by a force due to gravity as the revolving type developing device revolves such that toner is permitted to flow from the black toner cartridge when the door is open and toner is not permitted to flow between the black toner cartridge and a corresponding developing unit of the developing device when the door is closed. 
     
     
       32. A color image forming apparatus as claimed in  claim 19 , further comprising: 
       a stand for supporting the color image forming apparatus.  
     
     
       33. A color image forming apparatus as claimed in  claim 32 , wherein a height of the color image forming apparatus when being supported by the stand is less than or equal to 950 mm. 
     
     
       34. A color image forming apparatus as claimed in  claim 32 , wherein a height of the stand is at least 380 mm. 
     
     
       35. An apparatus according to  claim 19 , further comprising: 
       a fan which creates an air flow between said revolving type developing device and said fixing device for cooling said revolving type developing device.  
     
     
       36. An apparatus according to  claim 19 , wherein: 
       the length of said intermediate transfer belt is at least twice as great as the circumference of said image carrier.  
     
     
       37. An apparatus according to  claim 19 , wherein: 
       the length of said intermediate transfer belt is at least five times as great as the circumference of said image carrier.  
     
     
       38. A color image forming apparatus for forming a toner image on a sheet of paper, comprising: 
       
         an image carrier for sequentially forming toner images of respective colors thereon;  
       
       
         a charger which is proximate to said image carrier;  
       
       
         an exposure device for exposing said image carrier which has been charged and forming electrostatic latent images of respective colors on said image carrier;  
       
       
         a revolving type developing device which is rotatively supported in said color image forming apparatus such that a locus of the rotation of said revolving type developing device is overlapped with a locus of the rotation of said image carrier, said revolving type developing device including a plurality of color developing devices, each of which includes a developing unit for developing a toner image on said image carrier when said developing unit faces said image carrier;  
       
       
         an intermediate transfer medium which is disposed proximate to said image carrier such that said toner images are sequentially transferred on top of a previously transferred toner image on said intermediate transfer medium;  
       
       
         at least one paper feed tray for storing sheets of paper;  
       
       
         rollers which feed the sheets of paper one at a time from said at least one paper feed tray to said intermediate transfer medium from which said toner images are transferred to said sheets of paper; and  
       
       
         a fixing device for fixing said toner images on said sheets of paper,  
       
       
         wherein a length of said intermediate transfer medium is greater than a circumference of said image carrier. 
       
     
     
       39. An apparatus according to  claim 38 , wherein the revolving type developing device includes: 
       
         a toner chamber disposed at a circumferential portion of the revolving type developing device; and  
       
       
         a toner storage device connected to the toner chamber such that when the revolving  
       
       
         type developing device rotates, toner is transferred from the toner storage device to the toner chamber. 
       
     
     
       40. An apparatus according to  claim 39 , further comprising: 
       
         a door which opens and closes due to gravity as the revolving type developing device revolves such that toner is permitted to flow from the toner storage device to the toner chamber when the door is open and toner is not permitted to flow between the toner storage device to the toner chamber when the door is closed. 
       
     
     
       41. An apparatus according to  claim 40 , wherein: 
       
         the door is mounted to the toner chamber. 
       
     
     
       42. An apparatus as claimed in  claim 39 , wherein: 
       
         a length of said intermediate transfer medium with respect to the moving direction of said medium is an integral number of times a circumference of said image carrier. 
       
     
     
       43. An apparatus as claimed in  claim 42 , wherein said at least one paper feed tray comprises: 
       
         a duplex paper feed tray which is located under said image carrier, said revolving type developing device, said intermediate transfer medium, and said fixing device, said duplex paper feed tray arranged such that it holds paper during duplex image processing; and  
       
       
         a paper supply tray, separate from the duplex feed tray, for supporting paper on which images are formed. 
       
     
     
       44. An apparatus as claimed in  claim 43 , wherein said duplex paper feed tray is located above the paper supply tray. 
     
     
       45. An apparatus as claimed in  claim 38 , wherein: 
       
         a length of said intermediate transfer medium with respect to the moving direction of said medium is an integral number of times a circumference of said image carrier. 
       
     
     
       46. A color image forming apparatus for forming a toner image on a sheet of paper, comprising: 
       
         an image carrier for sequentially forming toner images of respective colors thereon:  
       
       
         a charger which is proximate to said image carrier;  
       
       
         an exposure device for exposing said image carrier which has been charged and forming electrostatic latent images of respective colors on said image carrier;  
       
       
         a revolving type developing device which is rotatively supported in said color image forming apparatus including a plurality of color developing devices, each of which includes a developing unit for developing a toner image on said image carrier when said developing unit faces said image carrier;  
       
       
         an intermediate transfer belt which is disposed proximate to said image carrier such that said toner images are sequentially transferred on top of a previously transferred toner image on said intermediate transfer belt;  
       
       
         at least one paper feed tray for storing sheets of paper;  
       
       
         rollers which feed the sheets of paper one at a time from said at least one paper feed tray to said intermediate transfer belt from which said toner images are transferred to said sheets of paper; and  
       
       
         a fixing device for fixing said toner images on said sheets of paper,  
       
       
         wherein a length of said intermediate transfer belt is greater than a circumference of said image carrier. 
       
     
     
       47. An apparatus according to  claim 46 , wherein the revolving type developing device includes: 
       
         a toner chamber disposed at a circumferential portion of the revolving type developing device; and  
       
       
         a toner storage device connected to the toner chamber such that when the revolving type developing device rotates, toner is transferred from the toner storage device to the toner chamber. 
       
     
     
       48. An apparatus according to  claim 47 , further comprising: 
       
         a door which opens and closes due to gravity as the revolving type developing device revolves such that toner is permitted to flow from the toner storage device to the toner chamber when the door is open and toner is not permitted to flow between the toner storage device to the toner chamber when the door is closed. 
       
     
     
       49. An apparatus according to  claim 48 , wherein: 
       
         the door is mounted to the toner chamber. 
       
     
     
       50. An apparatus as claimed in  claim 47 , wherein: 
       
         a length of said intermediate transfer belt with respect to the moving direction of said belt is an integral number of times a circumferential of said image carrier. 
       
     
     
       51. An apparatus as claimed in  claim 50 , wherein said at least one paper feed tray comprises: 
       
         a duplex paper feed tray which is located under said image carrier, said revolving type developing device, said intermediate transfer belt, and said fixing device, said duplex paper feed tray arranged such that it holds paper during duplex image processing; and  
       
       
         a paper supply tray, separate from the duplex feed tray, for supplying paper on which images are formed. 
       
     
     
       52. An apparatus as claimed in  claim 51 , wherein said duplex paper feed tray is located above the paper supply tray. 
     
     
       53. An apparatus as claimed in  claim 46 , wherein: 
       
         a length of said intermediate transfer belt with respect to the moving direction of said belt is an integral number of times a circumference of said image carrier.