Hard copy print media path for reducing cockle

• US 6,224,203 B1
• Filed: 05/13/1999
• Issued: 05/01/2001
• Est. Priority Date: 05/13/1999
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Rasmussen, Steve O., Wotton, Geoff
• Primary Examiner(s): Hilten, John S.
• Assistant Examiner(s): Chau, Minh H.
• Application Number:
  US09/312,372
• Time in Patent Office: 719 Days
• Field of Search: 347/101, 347/102, 347/104, 400/605, 400/648, 400/662
• US Class Current: 347/101
• CPC Class Codes: B41J 11/005 Guides in the printing zone, e.g. guides for preventing contact of conveyed sheets with printhead
• CPC Class Codes: B41J 11/007 Conveyor belts or like feeding devices
• CPC Class Codes: B41J 11/0085 Using suction for maintaining printing material flat on rotatable drums B41J13/226

Abstract

A wet-dye hard copy apparatus is provided with a vacuum transport for moving print media from and input, through a print zone, to an output. In order to reduce paper cockle, the print media is subjected to a post-printing predetermined bending while the print dye thereon is drying. In an alternative embodiment, a post-ejection bending heating step is added prior to ejecting a printed print medium to the apparatus output.

Claims

1. A method for reducing cockle of print media in a wet dye hard copy apparatus having a vacuum platen, comprising the steps of:

transporting the media along a paper path to a print zone of the apparatus superjacent the vacuum platen;

transporting the media along a continuing paper path through the print zone while printing on at least a first downstream region of the media in the print zone;

substantially immediately following printing on the downstream region of the media, bending the downstream region having wet print thereon along at least one predetermined radius of curvature for reducing cockle of the print media by bending the media having wet dye thereon along a predetermined first radius of curvature such that cockle amplitude is reduced, and following the step of bending the media, rebending the media having wet dye thereon along a second radius of curvature until the wet dye is substantially dry.

2. The method as set forth in claim 1, comprising the step of:

during bending of the downstream region, continuing transport of the media through the print zone and printing on an upstream region of the media.

3. The method as set forth in claim 1, the step of bending further comprises the step of:

bending the media such that wet dye print moves through a first radius of convex curvature having a range of 50 mm to 90 mm.

4. The method as set forth in claim 1, the step of rebending further comprises the step of:

recurving the media.

5. A wet-dye hard copy apparatus comprising:

printing means for depositing wet-dye on a print-side of a print medium in a print zone of the apparatus;

vacuum platen means for maintaining the print medium in the print zone in a substantially planar predetermined orientation to the printing means; and

transport means for moving the print medium through a paper path from an input side of the platen means through the print zone to an output side of the platen means, the paper path including means for inducing a cockle-reducing curvature of print medium regions having wet dye thereon, wherein the transport means includes a vacuum belt holddown, the vacuum belt holddown having a bend region for bending the print medium substantially immediately following deposit of wet dye thereon, and downstream of the bend region of the paper path, a bending means for forgoing the print medium into a concave radius of curvature.

6. The apparatus as set forth in claim 5, comprising:

the bend region forces the print medium regions having wet dye thereon into a convex radius of curvature.

7. The apparatus as set forth in claim 6, comprising:

the convex radius of curvature having a range of approximately 50 mm to 90 mm.

8. The apparatus as set forth in claim 5, comprising:

the bending means including a plate for receiving the print medium and forcing the print medium along a continuation of the paper path, said bending means having a concave radius of curvature having a range of approximately 20 mm to 30 mm.

9. An ink-jet print media transport device comprising:

a vacuum transport for moving print media sequentially through a paper path including a platen therein having an input side, a print zone, and an output side; and

the transport including mechanisms downstream of the print zone for inducing a cockle-reducing curvature of print medium regions having wet dye thereon, wherein the transport includes a vacuum belt holddown, the belt holddown having a bend region for bending the print medium substantially immediately following deposit of wet dye thereon at the print zone as the print media progresses through the paper path, and downstream of the bend region of the paper path, a bender device for forcing the print medium into a concave radius of curvature.

10. The device as set forth in claim 9, comprising:

the bend region forces the print medium regions having wet dye thereon into a convex radius of curvature.

11. The device as set forth in claim 10, comprising:

the convex radius of curvature having a range of approximately 50 mm to 90 mm.

12. The device asset forth in claim 9, comprising:

the bender device including a plate having a concave radius of curvature having a range of approximately 20 to 30 mm.

13. The device as set forth in claim 9, comprising:

in the paper path, following the bender device, a means for heating the print medium to press remaining cockle waves in the print medium to a substantially planar configuration.

14. A method for reducing cockle waves in a wet-dye ink-jet hard copy apparatus having a vacuum platen, comprising the steps of:

transporting a sheet of paper along a paper path to a printing zone of the apparatus superjacent the vacuum platen;

moving a wet sheet of printed paper along a post-printing zone curvilinear paper path such that wet ink on the sheet is kept from contact with any surface while bending the sheet through a first convex predetermined radius of curvature to reduce cockle waves; and

following bending the sheet through the first predetermined radius of curvature, heating the printed paper to press any remaining cockle into a substantially planar configuration and recurving the paper through a concave radius.