Method and apparatus for producing duplex copies

Abstract

Method and apparatus for producing duplex copies. First and second unfixed images are transferred to opposite sides of a copy sheet before fixing of either image to the copy sheet. The first and second unfixed images may be electroscopic images sequentially formed on a photoconductor by electrophotographic techniques. The first unfixed electroscopic image is transferred from the photoconductor to a first side of a copy sheet, the sheet is inverted while the first image thereon remains unfixed, the second unfixed electroscopic image is transferred to the second side of the copy sheet, the copy sheet with the first and second unfixed images thereon is then transported to a fixing station.

What is claimed is: .[.1. A method of producing first and second images on opposite sides respectively of a support comprising: 
     
        while said first image is unfixed. .Iaddend. .Iadd.13.  The method of claim 12 including fixing said first and second images to said copy sheet after transfer of said second unfixed image to said sheet. .Iaddend. .Iadd.14. An electrographic method of forming images on the opposite sides of a copy sheet, comprising: moving a photoconductive member along an endless path having first and second spaced image transfer stations;   forming first and second sequential adjacent unfixed toner images on said photoconductive member;   feeding a copy sheet into transfer relationship with said photoconductive member at said first image transfer station and transferring said first unfixed toner image to one side of said copy sheet;   while contacting the unimaged other side of said copy sheet without contacting said one side carrying said first unfixed toner image, separating said copy sheet from said photoconductive member and refeeding said copy sheet into transfer relationship with said photoconductive member at said second image transfer station; and   transferring said second toner image to the other side of said copy sheet while said first toner image is unfixed. .Iaddend. .Iadd.15. The method of claim 14 including fixing said first and second images to said copy sheet after transfer of said second toner image to said copy sheet. .Iaddend. .Iadd.16. The method of claim 14 wherein said forming of toner images includes forming first and second sequential adjacent electrostatic images on said photoconductive member; and   developing said first and second electrostatic images with toner particles to form first and second unfixed toner images on said photoconductive member. .Iaddend. .Iadd.17. The method of claim 14 wherein said separating of said copy sheet includes inverting said copy sheet after separation by contacting the unimaged other side of said sheet without contacting the one side carrying the unfixed toner image. .Iaddend. .Iadd.18. The method of claim 14 wherein said feeding of said copy sheet includes supplying a plurality of copy sheets in a supply and feeding copy sheets seriatim from said supply to said first transfer station. .Iaddend. .Iadd.19. The method of claim 14 wherein said separating said copy sheet includes vacuum contacting the unimaged other side of said copy sheet without contacting said one side carrying said first unfixed toner image. .Iaddend.   
     
     
        .Iadd.     A method of producing first and second images on opposite sides respectively of a support comprising: forming first and second transferable unfixed images on an image transfer member; and   transferring said first and second transferable unfixed images from said image transfer member to opposite sides respectively of a support before fixing of either of said unfixed images to said support by moving one side of a support into transfer relationship with said image transfer member for transfer of said first image and without contacting said one side with said first image, moving said support away from and back into transfer relationship with said image transfer member for transfer of said second image to the other side of said support. .Iaddend. .Iadd.21. The method of claim 20 including fixing said first and second images to said opposite sides of said support after transfer of both images to said support. .Iaddend. .Iadd.22. A method of producing duplex images on opposite sides of a copy sheet comprising:   forming first and second transferable unfixed images on first and second areas of an image transfer member;   transferring said first unfixed image from said transfer member to one side of a copy sheet;   without contacting said one side carrying said first unfixed image, moving said sheet away from and back into transfer relationship with said image transfer member; and   transferring said second unfixed image from said transfer member to the other side of the copy sheet before fixing of said first image to said sheet. .Iaddend. .Iadd.23. The method of claim 22 including simultaneous fixing of said first and second images to said copy sheet. .Iaddend. .Iadd.24. The method of claim 22 including inverting said copy sheet after transfer of said first unfixed image to said one side of said copy sheet while said first image is unfixed but before transfer of said second   
     
     
        unfixed image to said other side of said copy sheet. .Iaddend. .Iadd.25. A method of forming images on first and second sides of a copy sheet comprising the steps of: forming first and second sequential unfixed images on a photoconductor;   transferring said first unfixed image from said photoconductor to a first side of a copy sheet having first and second opposite sides;   without contacting said first side carrying said first unfixed image, moving said copy sheet away from and back into transfer relationship with said photoconductor;   transferring said second unfixed image from said photoconductor to the second side of said copy sheet before fixing of said first image to said copy sheet; and   transporting the copy sheet having said first and second unfixed images away from said photoconductor to a fixing station. .Iaddend. .Iadd.26. The method of claim 25 including the step of inverting said copy sheet after transfer of said first unfixed image to the first side thereof but before fixing of said first image to said first side so as to present the second side of said copy sheet for transfer of said second unfixed image on said photoconductor to said copy sheet second side. .Iaddend. .Iadd.27. The method of claim 25 including the step of fixing the first and second   
     
     
        unfixed images on said copy sheet. .Iaddend. .Iadd.28.  The method of claim 26 wherein said step of inverting includes contacting the second side of said copy sheet during copy sheet inversion without contacting said first side so as not to contact the first unfixed image on said first side of said copy sheet during sheet inversion and before transfer of said second unfixed image to said copy sheet. .Iaddend. .Iadd.29. A method of forming unfixed electroscopic images on first and second sides of a copy sheet before fixing of either image to said copy sheet comprising the steps of: forming first and second sequential electroscopic images on an endless photoconductive member;   transferring said first electroscopic image from said photoconductive member to the first of a copy sheet having first and second opposite sides;   without contacting said first side, inverting the copy sheet having said first unfixed electroscopic image on the first side thereof so as to present the second side thereof for transfer of the second electroscopic image on said photoconductive member to the second side of said copy sheet;   transferring the second electroscopic image from said photoconductive member to the second side of said copy sheet; and   transporting said copy sheet with said first and second unfixed images thereon to an image fixing station. .Iaddend. .Iadd.30. The method of claim 29 wherein said forming step comprises:   forming first and second electrostatic images on said photoconductive member; and   developing said first and second electrostatic images with electroscopic particles to form first and second visual unfixed images on said   
     
     
        photoconductive member. .Iaddend. .Iadd.31.  A method of forming images on first and second sides of a copy sheet comprising the steps of: forming first and second sequential unfixed images on a photoconductor;   transferring said first unfixed image from said photoconductor to a first side of a copy sheet having first and second opposite sides;   inverting said copy sheet after transfer of said first unfixed image to the first side thereof but before fixing of said first image to said first side so as to present the second side of said copy sheet for transfer of said second unfixed image on said photoconductor to said copy sheet's second side, said copy sheet inversion being effected by contacting the second side of said copy sheet during copy sheet inversion without contacting said first side so as not to contact the first unfixed image on said first side of said copy sheet during sheet inversion and before transfer of said second unfixed image to said copy sheet;   transferring said second unfixed image from said photoconductor to the second side of said copy sheet before fixing of said first image to said copy sheet; and   transporting the copy sheet having said first and second unfixed images away from said photoconductor to a fixing station. .Iaddend.