Apparatuses and methods for printing security documents

Patent metadata

Field	Value
Publication number	US-12017469-B2
Application number	US-201917288368-A
Country	US
Kind code	B2
Filing date	Oct 25, 2019
Priority date	Oct 26, 2018
Publication date	Jun 25, 2024
Grant date	Jun 25, 2024

Abstract

A digital printing press for printing security documents is provided. The digital printing press comprises: a first digital print head, the first digital printhead comprising a first array of print nozzles having a first nozzle diameter; a second digital print head, the second digital print head comprising a second array of print nozzles having a second nozzle diameter different from the first nozzle diameter; optionally, an offset printing unit, the offset printing unit comprising one or more offset printing surfaces, wherein the offset printing unit is adapted to transport a print area of the one or more offset printing surfaces sequentially past each of the first and second digital print heads, and subsequently to transfer print received from the first and second digital print heads to a security document substrate; a transport system adapted to transport a security document substrate along a transport path through the digital printing press, wherein either the transport path takes the security document sequentially past each of the first and second digital print heads in a feed direction, or the transport path takes the security document substrate past the offset printing unit, if provided, in a feed direction; a controller adapted to control both the first and second digital print heads to execute a set of printing instructions so as to print on a security document substrate transported past the first and second digital print heads by the transport system or to print on the print area of the one or more offset printing surfaces transported past the first and second digital print heads by the offset printing unit (and to transfer the print received on the print area of the offset printing to the security document substrate), the set of printing instructions including printing instructions at a first resolution for the first digital print head for printing a first print working and printing instructions at a second resolution different from the first resolution for the second digital print head for printing a second print working; wherein the first digital print head is configured to print at the first resolution and the second digital print head is configured to print at the second resolution, and wherein the first and second digital print heads are configured or controlled by the controller to remain static relative to the transport path or offset printing unit while the first and second digital print heads execute the respective printing instructions.

First claim

The invention claimed is:

1. A digital printing press for printing security documents, the digital printing press comprising:
a first digital print head, the first digital print head comprising a first array of print nozzles having a first nozzle diameter;
a second digital print head, the second digital print head comprising a second array of print nozzles having a second nozzle diameter different from the first nozzle diameter;
optionally, an offset printing unit, the offset printing unit comprising one or more offset printing surfaces, wherein the offset printing unit is adapted to transport a print area of the one or more offset printing surfaces sequentially past each of the first and second digital print heads, and subsequently to transfer print received from the first and second digital print heads to a security document substrate;
a transport system adapted to transport a security document substrate along a transport path through the digital printing press, wherein either the transport path takes the security document sequentially past each of the first and second digital print heads in a feed direction, or the transport path takes the security document substrate past the offset printing unit, if provided, in a feed direction; and
a controller adapted to control both the first and second digital print heads to execute a set of printing instructions so as to print on a security document substrate transported past the first and second digital print heads by the transport system or to print on the print area of the one or more offset printing surfaces transported past the first and second digital print heads by the offset printing unit and to transfer the print received on the print area of the offset printing to the security document substrate, the set of printing instructions including printing instructions at a first resolution for the first digital print head for printing a first print working and printing instructions at a second resolution different from the first resolution for the second digital print head for printing a second print working;
wherein the first digital print head is configured to print at the first resolution and the second digital print head is configured to print at the second resolution, and wherein the first and second digital print heads are configured or controlled by the controller to remain static relative to the transport path or offset printing unit while the first and second digital print heads execute the respective printing instructions.

2. The digital printing press according to claim 1 , wherein the first digital print head has a first cross-feed resolution and the second digital print head has a second cross-feed resolution different from the first cross-feed resolution, and wherein the printing instructions for the first digital print head are at a resolution corresponding to the first cross-feed resolution and the printing instructions for the second digital print head are at a resolution corresponding to the second cross-feed resolution.

3. The digital printing press according to claim 1 , wherein the controller is adapted to control the first print head to print at a first feed direction resolution and to control the second print head to print at a second feed direction resolution different from the first feed direction resolution, and wherein the printing instructions for the first digital print head are at a resolution corresponding to the first feed direction resolution and the printing instructions for the second digital print head are at a resolution corresponding to the second feed direction resolution.

4. The digital printing press according to claim 1 , wherein the first digital print head is configured to print at least one dot size smaller than, preferably at least 25% smaller than, more preferably 50% smaller than, the smallest dot size printable by the second digital print head and/or wherein the second digital print head is configured to print at least one dot size larger than, preferably 50% larger than, more preferably 100% larger than, the largest dot size printable by the first digital print head.

5. The digital printing press according to claim 1 , wherein the first resolution is at least 600 DPI, preferably at least 900 DPI, more preferably at least 1200 DPI, in either or both of the feed direction and the cross-feed direction, and wherein the second resolution is at most 600 DPI, preferably at most 360 DPI, further preferably at most 200 DPI, in either or both of the feed direction and the cross-feed direction.

6. The digital printing press according to claim 1 , wherein the first digital print head is an inkjet print head and is configured to print with at least one drop size of at most 50 picolitres, preferably at most 30 picolitres, more preferably at most 10 picolitres, most preferably at most 5 picolitres, and wherein the second digital print head is an inkjet print head and is configured to print with at least one drop size of at least 10 picolitres, preferably at least 30 picolitres, more preferably at least 50 picolitres, most preferably at least 100 picolitres.

7. The digital printing press according to claim 1 , wherein the first digital print head, the second digital print head and the transport system are configured such that the first digital print is controllable to print the first print working on the substrate in a first region and the second digital print is controllable to print the second print working on the substrate in a second region, the first and second regions at least partially overlapping one another.

8. The digital printing press according to claim 1 , wherein the first and/or second nozzle diameters are in the range 1 to 100 microns, preferably in the range 6 to 80 microns, wherein preferably one of the first and second nozzle diameters is in the range 1 to 40 microns, preferably in the range 6 to 20 microns, and the other is in the range 40 to 100 microns, preferably in the range 60 to 80 microns.

9. The digital printing press according to claim 1 , wherein the first digital print head comprises a first array of print nozzles having a first pitch in a direction transverse to the transport path and wherein the second digital print head comprises a second array of print nozzles having a second pitch in the direction transverse to the transport path, the second pitch being different from the first pitch.

10. The digital printing press according to claim 9 , wherein one of the first and second pitches is a non-integer multiple of the other.

11. A digital printing press according to claim 9 , wherein the first and second pitches are between 300 microns and 10 microns.

12. The digital printing press according to claim 1 , wherein the first digital print head is configured or controllable by the controller to print with one or more drop sizes, and wherein the second digital print head is configured or controllable by the controller to print with one or more drop sizes, and wherein the one or more drop sizes of the first digital print head is different from the one or more drop sizes of the second digital print head.

13. The digital printing press according to claim 1 , further comprising a corona treatment unit configured to perform a corona treatment on the surface of the security document substrate, wherein the transport path of the transport system takes the security document substrate past the corona treatment unit upstream of the digital print heads and/or offset printing unit.

14. The digital printing press according to claim 1 , further comprising a finishing digital print head, the finishing digital print head configured to print a varnish coating onto the

Assignees

• De La Rue Int Ltd

Inventors

• Parab Nikhil
• Wallis Andrew Francis
• Bannon Martin

Classifications

• B41J2/2125

  by means of nozzle diameter selection · CPC title

• B41M3/14

  Security printing {(securities B42D25/29)} · CPC title

• B42D25/378

  Special inks · CPC title

• B42D25/373

  Metallic materials · CPC title

• B42D25/305

  Associated digital information (record carriers for use with machines and with at least a part designed to carry digital markings G06K19/00) · CPC title