Image registration correction for non-impact printers

Claim 2

In an apparatus for operatively relating the cyclicly operated photosensitive surface of a xerographic processor with the continuously rotating character drum of a character generator in an impactless printer, the combination of: optical projection means operatively disposed between said character drum and said photosensitive surface for projecting character images generated by said character generator onto said processor photosensitive surface, said character generator being adapted to start printout at a predetermined character drum position; and means responding to a delay by said character generator in starting printout while said character drum rotates to said predetermined position to move said optical projection means and re-position the image projected thereby on said processor photosensitive surface so as to compensate for the delay in starting printout.

Claim 3

The apparatus according to claim 1 in which said character drum is segregated into sectors of at least one character set each, said moving means including means adapted to drive said optical projection means through a series of steps, there being at least one step for each of said character drum sectors, and comparator means for identifying the sector position of said character drum at the start-print signal and comparing said drum sector position with said drum predetermined start printout position; and control means for actuating said drive means to step said optical projection means through the step or steps equal to the number of full sectors difference in drum position as sensed by said comparator means.

Claim 4

The apparatus according to claim 1 in which said optical projection means includes at least one projection lens of predetermined magnification together with at least one character mask in operative association therewith; said moving means being adapted to move said mask relative to said lens in a ratio substantially equal to the magnification ratio of said lens.

Claim 5

In an electrostatic line printer, the combination of: a xerographic processor having a photosensitive imaging surface; character generating means including a rotatable character drum separated into equal sectors with plural alpha-numeric character columns in each of said sectors; one of said sectors defining start of line printing position for said drum; means to illuminate selected ones of said character at a predetermined printing position of said drum whereby to provide light images of those characters comprising the lines being printed; optical means to project said light images onto said processor photosensitive imaging surface; means to step said optical means through a series of incremental movements corresponding to said drum sectors whereby the light image projected by said optical means on said imaging surface is incrementally displaced; and control means responsive to an enabling signal from said processor to actuate said step means and step said optical means when the instantaneous position of said drum at the time of said enabling signal is at least one sector apart from said one start of line printing sector, said control means being adapted to sustain actuation of said step means until said optical means is moved through steps equal to the number of sectors by which said drum instantaneous position is apart from said one start of line printing sector.

Claim 6

In an electrostatic line printer, the combination of: a xerographic processor having a photosensitive imaging surface; character generating means including a rotatable character drum separated into equal sectors with plural alpha-numeric character columns in each of said sectors; one of said sectors defining start of line printing position for said drum; means to illuminate selected ones of said character at a predetermined printing position of said drum whereby to provide light images of those characters comprising the lines being printed; optical means to project said light images onto said processor photosensitive imaging surface; means to step said optical means through a series of incremental movements corresponding to said drum sectors whereby the light image projected by said optical means on said imaging surface is incrementally displaced; and control means responsive to an enabling signal from said processor to actuate said step means and step said optical means when the instantaneous position of said drum at the time of said enabling signal is at least one sector apart from said one start of line printing sector, said control means being adapted to sustain actuation of said step means until said optical means is moved through steps equal to the number of sectors by which said drum instantaneous position is apart from said one start of line printing sector.

Claim 7

The electrostatic type line printer according to claim 4 in which said optical projection means includes at least one lens and cooperating mask for projecting character images from said character drum to said photosensitive surface; said step means including a first driver for said lens; a second driver for said mask; said second driver being adapted to move said mask by an amount equal to the movement of said lens times the magnification ratio of said lens.

Claim 8

The electrostatic type line printer according to claim 4 in which said processor enabling signal reflects start of page printing.

Claim 9

In a non-impact printing apparatus, a xerographic processor having a member with a photosensitive surface, said xerographic processor generating a start-print signal when said photosensitive surface is at a predetermined position, a character generator having a continuously rotating, character-bearing member, said character generator being adapted to start printout when said character-bearing member is at a predetermined printout position, optical projection means operatively disposed between said continuously rotating member and said photosensitive surface for projecting character images generated by said character generator onto said photosensitive surface, and means responding to a delay by said character generator in starting printout, due to said character-bearing member not being at said predetermined printout position when said xerographic processor generates said Start-print signal, to move said optical projection means to compensate for the delay in starting printout.

Claim 10

In a non-impact printing apparatus, a xerographic processor having a member with a photosensitive surface, said xerographic processor generating a start-print signal when said photosensitive surface is at a predetermined position, a character generator having a continuously rotating, character-bearing member, said character generator being adapted to start printout when said character-bearing member is at a predetermined printout position, optical projection means operatively disposed between said continuously rotating member and said photosensitive surface for projecting character images generated by said character generator onto said photosensitive surface, and means responding to a delay by said character generator in starting printout, due to said character-bearing member not being at said predetermined printout position when said xerographic processor generates said Start-print signal, to move said optical projection means to compensate for the delay in starting printout.

Claim 11

The apparatus of claim 7 in which said character-bearing member is a drum segregated into sectors of at least one character set each, said moving means includes means adapted to drive said optical projection means through a series of steps, there being at least one step for each of said character drum sectors, and comparator means for identifying the sector position of said character-bearing drum at the start-print signal and comparing said drum sector position with said predetermined printout position, and control means for actuating said drive means to step said optical projection means through the step or steps equal to the number of full sectors difference in drum position as sensed by said comparator means.

Claim 14

The method of claim 9 wherein said movement is achieved by displacing the means optically coupling said character bearing drum with said photosensitive surface in step-wise fashion, one step for each sector difference.