Method and apparatus for producing duplex copies

Claim 2

Apparatus for producing first and second images on first and second sides respectively of a copy sheet before producing images on a successive copy sheet, comprising: a movable image transfer member; means for forming first and second sequential adjacent transferable unfixed images on said image transfer member; and means located in transfer relation with said transfer member for transferring said first and second sequential adjacent transferable unfixed images directly from said image transfer member to first and second sides respectively of a copy sheet brought into transfer relation with said transfer member before fixing of either of said unfixed images to said copy sheet and before transferring images to a successive copy sheet.

Claim 3

The apparatus of claim 1 including means for fixing said first and second images to said copy sheet after transfer of both of said unfixed images to said copy sheet.

Claim 4

In apparatus for producing images on first and second sides of a copy sheet before producing images on a successive copy sheet, said apparatus including a movable image transfer member, means for forming first and second sequential adjacent transferable images on said image transfer member and means for transferring said first and second transferable images to said first and second sides respectively of said copy sheet, the improvement wherein said means for transferring includes means for transferring said first and second images directly from said transfer member to said first and second sides of a copy sheet prior to fixing of either of said images to said copy sheet and before transferring images to a successive copy sheet.

Claim 5

In apparatus for producing images on first and second sides of a copy sheet before producing images on a successive copy sheet, said apparatus including a movable image transfer member, means for forming first and second sequential adjacent transferable images on said image transfer member and means for transferring said first and second transferable images to said first and second sides respectively of said copy sheet, the improvement wherein said means for transferring includes means for transferring said first and second images directly from said transfer member to said first and second sides of a copy sheet prior to fixing of either of said images to said copy sheet and before transferring images to a successive copy sheet.

Claim 6

The apparatus of claim 3 including means for fixing said unfixed images to said copy sheet.

Claim 7

Apparatus for forming images on first and second sides of a copy sheet before fixing of either image and before forming images on a successive copy sheet, comprising: a movable image transfer member; means for forming sequential adjacent first and second transferable unfixed images on said transfer member; a first image transfer station; a second image transfer station spaced from said first transfer station; copy sheet inverting means positioned between said first and second transfer stations for inverting a copy sheet after transfer of said first image from said transfer member at said first transfer station to a first side of the copy sheet but before fixing of said first image by contacting the second unimaged side of said copy sheet without contacting said first side with said first image and for registering the second side of said copy sheet with the second sequential adjacent image on said transfer member at said second transfer station for transfer of said second image to said second side of said copy sheet before transfer of any image to a successive copy sheet; and means for feeding said copy sheet into transfer relation with said image transfer member at said first transfer station with said first side of said copy sheet in registration with said first image on said transfer member.

Claim 8

Apparatus for forming images on first and second sides of a copy sheet before fixing of either image and before forming images on a successive copy sheet, comprising: a movable image transfer member; means for forming sequential adjacent first and second transferable unfixed images on said transfer member; a first image transfer station; a second image transfer station spaced from said first transfer station; copy sheet inverting means positioned between said first and second transfer stations for inverting a copy sheet after transfer of said first image from said transfer member at said first transfer station to a first side of the copy sheet but before fixing of said first image by contacting the second unimaged side of said copy sheet without contacting said first side with said first image and for registering the second side of said copy sheet with the second sequential adjacent image on said transfer member at said second transfer station for transfer of said second image to said second side of said copy sheet before transfer of any image to a successive copy sheet; and means for feeding said copy sheet into transfer relation with said image transfer member at said first transfer station with said first side of said copy sheet in registration with said first image on said transfer member.

Claim 9

Electrophotographic apparatus for producing duplex copies comprising: an endless movable photoconductive member; image forming means for forming first and second sequential adjacent electroscopic images on said photoconductive member; first transfer means for transferring said first electroscopic image from said photoconductive member to the first side of a copy sheet having first and second opposite sides; sheet inverting means for inverting said copy sheet having said first electroscopic image on the first side thereof before fixing of said first image to said sheet by contacting said second unimaged side thereof without contacting said first side with said first image and for presenting the second side thereof in transfer relation with said photoconductive member for transfer of the second electroscopic image on said photoconductive member to said second side of said copy sheet; and second transfer means for transferring said second electroscopic image from said photoconductive member to said second side of said copy sheet before transfer of any image to a successive copy sheet.

Claim 10

Electrophotographic apparatus for producing duplex copies comprising: an endless movable photoconductive member; image forming means for forming first and second sequential adjacent electroscopic images on said photoconductive member; first transfer means for transferring said first electroscopic image from said photoconductive member to the first side of a copy sheet having first and second opposite sides; sheet inverting means for inverting said copy sheet having said first electroscopic image on the first side thereof before fixing of said first image to said sheet by contacting said second unimaged side thereof without contacting said first side with said first image and for presenting the second side thereof in transfer relation with said photoconductive member for transfer of the second electroscopic image on said photoconductive member to said second side of said copy sheet; and second transfer means for transferring said second electroscopic image from said photoconductive member to said second side of said copy sheet before transfer of any image to a successive copy sheet.

Claim 11

The apparatus of claim 6 wherein said inverting means includes a reversible vacuum belt.

Claim 12

The apparatus of claim 6 including means for fixing said first and second electroscopic images on said copy sheet at an image fixing station.

Claim 13

The apparatus of claim 6 wherein said first transfer means, said sheet inverting means and said second transfer means are located along the path of said photoconductive member so as to minimize the distance between first and second electroscopic images formed thereon.

Claim 14

Apparatus for producing first and second images on first and second sides respectively of a copy sheet, before producing images on a successive copy sheet, comprising: a movable image transfer member; means for forming first and second sequential adjacent transferable unfixed images on first and second consecutive areas of said image transfer member; first transfer means for transferring said first unfixed image from said transfer member to the first side of a copy sheet; second transfer means for transferring said second sequential adjacent unfixed image from said transfer member to the second side of said copy sheet before fixing of said first image to said sheet; and means for feeding said copy sheet into transfer relation with said image transfer member at said first and second transfer means in respective registration with said first and second images on said transfer member for sequential transfer of said first and second images to said first and second sides of said copy sheet before transfer of any image to a successive copy sheet.

Claim 15

Apparatus for producing first and second images on first and second sides respectively of a copy sheet, before producing images on a successive copy sheet, comprising: a movable image transfer member; means for forming first and second sequential adjacent transferable unfixed images on first and second consecutive areas of said image transfer member; first transfer means for transferring said first unfixed image from said transfer member to the first side of a copy sheet; second transfer means for transferring said second sequential adjacent unfixed image from said transfer member to the second side of said copy sheet before fixing of said first image to said sheet; and means for feeding said copy sheet into transfer relation with said image transfer member at said first and second transfer means in respective registration with said first and second images on said transfer member for sequential transfer of said first and second images to said first and second sides of said copy sheet before transfer of any image to a successive copy sheet.

Claim 16

The apparatus of claim 10 including means for fixing said first and second images to said copy sheet.

Claim 17

The apparatus of claim 10 wherein said copy sheet feeding means includes means for inverting said copy sheet after transfer of said first unfixed image to said first side of said copy sheet but before transfer of said second unfixed image to said second side of said copy sheet and while said first image is unfixed on said copy sheet by contacting said second unimaged side thereof without contacting said first side carrying said first unfixed image.

Claim 18

Apparatus for producing images on first and second sides of a copy sheet before producing images on a successive copy sheet, comprising: a movable photoconductive member; means for forming first and second sequential adjacent unfixed toner images on said photoconductive member; first transfer means located adjacent said photoconductive member for transferring said first unfixed toner image from said photoconductive member to a first side of a copy sheet having first and second sides; second transfer means located adjacent said photoconductive member for transferring said second unfixed toner image from said photoconductive member to the second side of said copy sheet before fixing of said first toner image to said copy sheet; and means for feeding said copy sheet into transfer relationship with said photoconductive member at said first and second transfer means in respective registration with said first and second sequential adjacent toner images on said photoconductive member so that said first and second images are transferred to said copy sheet before images are transferred to a successive copy sheet.

Claim 19

Apparatus for producing images on first and second sides of a copy sheet before producing images on a successive copy sheet, comprising: a movable photoconductive member; means for forming first and second sequential adjacent unfixed toner images on said photoconductive member; first transfer means located adjacent said photoconductive member for transferring said first unfixed toner image from said photoconductive member to a first side of a copy sheet having first and second sides; second transfer means located adjacent said photoconductive member for transferring said second unfixed toner image from said photoconductive member to the second side of said copy sheet before fixing of said first toner image to said copy sheet; and means for feeding said copy sheet into transfer relationship with said photoconductive member at said first and second transfer means in respective registration with said first and second sequential adjacent toner images on said photoconductive member so that said first and second images are transferred to said copy sheet before images are transferred to a successive copy sheet.

Claim 20

The apparatus of claim 13 wherein said feeding means includes means for inverting said copy sheet after transfer of said first unfixed toner image to the first side thereof but before fixing of said first toner image and for registering the second side of said copy sheet with said second unfixed toner image on said photoconductive member at said second transfer means.

Claim 21

The apparatus of claim 13 including means for fixing said first and second unfixed images to said copy sheet.

Claim 22

The apparatus of claim 13 wherein said means for feeding includes means for contacting the second side of said copy sheet between transfer of said first and second images without contacting said first side so as not to disturb the first unfixed toner image on said first side of said copy sheet.

Claim 23

Apparatus for producing unfixed toner images on first and second sides of a copy sheet before fixing of either image to said copy sheet and before producing images on a successive copy sheet, comprising: a movable photoconductive member; means for forming first and second sequential adjacent unfixed toner images on said movable photoconductive member; first and second image transfer means located adjacent said photoconductive member for transferring said first and second unfixed toner images from said photoconductive member to the first and second sides respectively of a copy sheet before transfer of any images to a successive copy sheet; means for feeding the first side of a copy sheet into registration with said first toner image on said photoconductive member at said first image transfer means; a reversible vacuum belt located adjacent said photoconductive member between said first and second image transfer means movable in a first direction to contact said second unimaged side of said copy sheet to separate said copy sheet having a first unfixed toner image on the first side thereof from transfer relation with said photoconductive member by vacuum attraction of the copy sheet to the belt and in a second opposite direction to turn said copy sheet over while said first toner image remains unfixed and without contacting said first side to register the second side of said copy sheet with said second toner image on said photoconductive member at said second transfer means; and control means operatively associated with said movable photoconductive member, and said vacuum belt for controlling the movement of said belt in said first and second directions in synchronism with the images formed on said photoconductive member.

Claim 24

Apparatus for producing unfixed toner images on first and second sides of a copy sheet before fixing of either image to said copy sheet and before producing images on a successive copy sheet, comprising: a movable photoconductive member; means for forming first and second sequential adjacent unfixed toner images on said movable photoconductive member; first and second image transfer means located adjacent said photoconductive member for transferring said first and second unfixed toner images from said photoconductive member to the first and second sides respectively of a copy sheet before transfer of any images to a successive copy sheet; means for feeding the first side of a copy sheet into registration with said first toner image on said photoconductive member at said first image transfer means; a reversible vacuum belt located adjacent said photoconductive member between said first and second image transfer means movable in a first direction to contact said second unimaged side of said copy sheet to separate said copy sheet having a first unfixed toner image on the first side thereof from transfer relation with said photoconductive member by vacuum attraction of the copy sheet to the belt and in a second opposite direction to turn said copy sheet over while said first toner image remains unfixed and without contacting said first side to register the second side of said copy sheet with said second toner image on said photoconductive member at said second transfer means; and control means operatively associated with said movable photoconductive member, and said vacuum belt for controlling the movement of said belt in said first and second directions in synchronism with the images formed on said photoconductive member.

Claim 25

The apparatus of claim 17 wherein said means for forming includes: means for producing first and second electrostatic images on said photoconductive member; and means for developing said first and second electrostatic images with toner particles to form said first and second unfixed toner images on said photoconductive member.