Method and apparatus for the seamless engraving of half-tone printing plates

Claim 2

In a system for producing half-tone screen printing cylinders: a master cylinder having an image portion interrupted circumferentially by a seam of known circumferential width; a printing cylinder upon which the image on said master cylinder, at least substantially exclusive of said seam, is to be engraved; means for circumferentially scanning said master cylinder to produce a selected number of engraving signals per complete circumferential scan cycle and including a number of certain engraving signals corresponding to the circumferential width of said seam; means for circumferentially engraving said printing cylinder in accord with said engraving signals during each engrave cycle, and means for causing a selected number of said engraving signals corresponding to different parts of said image portion from throughout said image to be engraved twice and a corresponding selected number of said certain engraving signals corresponding to said seam to be skipped during each circumferential engrave cycle.

Claim 3

In a system for producing half-tone screen printing cylinders as defined in claim 1 wherein said selected number of engraving signals is substantially equal to said certain number of engraving signals corresponding to said width of the seam.

Claim 4

In a system for producing half-tone screen printing cylinders as defined in claim 1 wherein the last mentioned means comprises a plurality of storage members connected as a serial shift register and gate means for passing signals from one storage member at a time to said means for engraving, said gate means including a plurality of gates associated with said storage members and control means for periodically stepping from one storage member to the next as the output to said means for engraving.

Claim 5

In a system for producing half-tone screen printing cylinders as defined in claim 3 wherein said plurality of gates is equal to one more than said selected number of engraving signals to be skipped.

Claim 6

In a system for producing half-tone screen printing cylinders as defined in claim 4 wherein said engraving signals are connected to the first of said series of storage members and the serial shift register comprised of said storage members is shifted at the same rate as the engraving signals are generated.

Claim 7

Apparatus for producing a half-tone image on a cylindrical printing cylinder which occupies the entire circumference of the printing cylinder along a certain length thereof and which is derived from an image on a master cylinder which occupies slightly less than the full circumference thereof due to the presence of a longitudinal seam, said apparatus comprising: means for rotating said master cylinder and said printing cylinder in unison; means for scanning said master cylinder point-by-point and line-by-line over the longitudinal length of the image thereon, and for producing a selected number of point-by-point engraving signals per complete revolution of said master cylinder and said printing cylinder whereby certain of said engraving signals per revolution correspond to the presence of said seam; means for engraving said printing cylinder point-by-point and line-by-line in accord with said engraving signals and to produce, per complete revolution of said printing cylinder, a number of engraving points equal to said selected number of engraving signals; and means for eliminating at least substantially all of said certain engraving signals per revolution which correspond to said seam and replacing them by repeated engraving signals generated from different portions of said image from throughout said image on the master cylinder.

Claim 8

Apparatus for producing a half-tone image on a cylindrical printing cylinder which occupies the entire circumference of the printing cylinder along a certain length thereof and which is derived from an image on a master cylinder which occupies slightly less than the full circumference thereof due to the presence of a longitudinal seam, said apparatus comprising: means for rotating said master cylinder and said printing cylinder in unison; means for scanning said master cylinder point-by-point and line-by-line over the longitudinal length of the image thereon, and for producing a selected number of point-by-point engraving signals per complete revolution of said master cylinder and said printing cylinder whereby certain of said engraving signals per revolution correspond to the presence of said seam; means for engraving said printing cylinder point-by-point and line-by-line in accord with said engraving signals and to produce, per complete revolution of said printing cylinder, a number of engraving points equal to said selected number of engraving signals; and means for eliminating at least substantially all of said certain engraving signals per revolution which correspond to said seam and replacing them by repeated engraving signals generated from different portions of said image from throughout said image on the master cylinder.

Claim 9

Apparatus according to claim 6 wherein the last means comprises serial shift register means receiving said engraving signals, control means for shifting out said shift register means in parallel, and gate means for selecting one of the parallel outputs at a time to control said means for engraving.

Claim 10

Apparatus according to claim 7 wherein said gate means includes a number of serially selected gates equal in number to one more than the number of engraving signals which are eliminated per revolution.

Claim 13

The method of producing a half-tone image as defined in claim 9 wherein the repetitively engraved scanning points of step (c) are distributed throughout the image on the printing cylinder.

Claim 14

The method of producing a half-tone image as defined in claim 10 wherein each repetitively engraved scanning point is engraved twice in succession.

Claim 15

Apparatus for producing a half-tone image on a cylindrical printing cylinder which occupies the entire circumference of the printing cylinder along a certain length thereof and which is derived from an image on a master cylinder which occupies slightly less than the full circumference Thereof due to the presence of a longitudinal seam, said apparatus comprising: means for rotating said master cylinder and said printing cylinder in unison; means for scanning said master cylinder point-by-point and line-by-line over the longitudinal length of the image thereon, and for producing a selected number of point-by-point engraving signals per complete revolution of said master cylinder and said printing cylinder whereby certain of said engraving signals per revolution correspond to the presence of said seam; means for engraving said printing cylinder point-by-point and line-by-line in accord with said engraving signals and to produce, per complete revolution of said printing cylinder, a number of engraving points equal to said selected number of engraving signals; means for eliminating substantially all of said certain engraving signals per revolution which correspond to said seam; and means for repeating a sufficient number of engraving signals generated from different portions of said image, from throughout said image on the master cylinder remote from said seam as to replace the eliminated engraving signals.

Claim 16

Apparatus for producing a half-tone image on a cylindrical printing cylinder which occupies the entire circumference of the printing cylinder along a certain length thereof and which is derived from an image on a master cylinder which occupies slightly less than the full circumference Thereof due to the presence of a longitudinal seam, said apparatus comprising: means for rotating said master cylinder and said printing cylinder in unison; means for scanning said master cylinder point-by-point and line-by-line over the longitudinal length of the image thereon, and for producing a selected number of point-by-point engraving signals per complete revolution of said master cylinder and said printing cylinder whereby certain of said engraving signals per revolution correspond to the presence of said seam; means for engraving said printing cylinder point-by-point and line-by-line in accord with said engraving signals and to produce, per complete revolution of said printing cylinder, a number of engraving points equal to said selected number of engraving signals; means for eliminating substantially all of said certain engraving signals per revolution which correspond to said seam; and means for repeating a sufficient number of engraving signals generated from different portions of said image, from throughout said image on the master cylinder remote from said seam as to replace the eliminated engraving signals.