Printer with sheet feeding past multiple printheads

Abstract

A printer includes: a first fixed printhead having a respective first print zone; a second fixed printhead positioned downstream of the first printhead relative to a media feed direction, the second printhead having a respective second print zone; an input roller assembly positioned upstream of the first platen, the input roller assembly being configured for feeding media sheets along a downward trajectory towards the first print zone; and an intermediary roller assembly positioned between the first and second print zones, the intermediary roller assembly being configured for receiving the media sheets from the first print zone and feeding the media sheets along a downward trajectory. The second print zone is positioned relatively lower than the first print zone.

Claims

1. A printer comprising: a first fixed printhead having a respective first print zone; a second fixed printhead positioned downstream of the first printhead relative to a media feed direction, the second printhead having a respective second print zone; an input roller assembly positioned upstream of the first print zone, the input roller assembly being configured for feeding media sheets along a downward trajectory, relative to the first printhead, towards the first print zone; and an intermediary roller assembly positioned between the first and second print zones, the intermediary roller assembly being configured for receiving the media sheets from the first print zone and feeding the media sheets along a downward trajectory, relative to the second printhead, towards the second print zone, wherein the second print zone is positioned relatively lower than the first print zone.

2. The printer of claim 1, wherein a nozzle plate of the second printhead is positioned relatively lower than a nozzle plate of the first printhead.

3. The printer of claim 1, wherein the first and second printheads are positioned in an overlapping arrangement with respect to the media feed direction.

4. The printer of claim 1, wherein the input roller assembly comprises a pair of input rollers defining a first nip therebetween, wherein the first nip is positioned relatively higher than the first print zone.

5. The printer of claim 1, wherein the intermediary roller assembly comprises a pair of intermediary rollers defining an intermediary nip therebetween, wherein the intermediary nip is positioned relatively higher than the second print zone.

6. The printer of claim 1 comprising a single pair of intermediary rollers.

7. The printer of claim 1, wherein each of the first and second print zones has a respective platen positioned therein.

8. The printer of claim 1, wherein an exit roller assembly is positioned downstream of the second print zone.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

(2) FIG. 1 is a schematic side view of a printer with printheads and feed mechanism according to the present invention; and

(3) FIG. 2 is a schematic plan view of the printer shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

(4) Referring to FIG. 1, there is shown a printer 1 comprising a first fixed printhead 3 and a second fixed printhead 5 positioned downstream of the first printhead relative to a media feed direction D. A first platen 7 is positioned in a respective first print zone 9 of the first printhead 5. Similarly, a second platen 11 is positioned in a second print zone 13 of the second printhead 7.

(5) An input roller assembly 15 is comprised of a pair of input rollers 16A and 16B positioned upstream of the first platen 7. The input roller assembly 15 receives a media sheet 17 and is configured to feed the sheet along the media feed direction (indicated by arrow D) in a generally downward trajectory onto an upper surface of the first platen 7. Accordingly, a nip defined between the input rollers 16A and 16B is positioned relatively higher than the upper surface of the first platen 7. The media sheet 17 is transported through the first print zone 9 and receives ink droplets from the first printhead 3 to form a first part of an image.

(6) An intermediary roller assembly 19 is comprised of a pair of intermediary rollers 20A and 20B positioned downstream of the first platen 7 relative to the media feed direction D. The intermediary roller assembly 19 is configured for receiving the media sheet 17 from the first platen 7 and feeding the media sheet in a generally downward trajectory towards the second platen 11. Accordingly, a nip defined between the intermediary rollers 20A and 20B is positioned relatively higher than the upper surface of the second platen 11. The media sheet 17 is transported through the second print zone 13 and receives ink droplets from the second printhead 5 to form a second part of the image.

(7) As shown in FIG. 2, the first printhead 3 and the second printhead 5 partially overlap in the media feed direction D, with each printhead printing about half of the image (not shown). Suitable algorithms may be employed to mask any stitching artifacts between the two printheads using techniques known in the art (see, for example, U.S. Pat. No. 6,394,573, the contents of which are incorporated herein by reference). Alternatively, the two parts of the image may be stitched by selecting a suitable stitching point for the two printheads and joining the two parts of the image via a simple butt join. These and other methods for stitching images printed by a plurality of fixed printheads will be readily apparent to the person skilled in the art.

(8) Returning to FIG. 1, an exit roller assembly 21 is comprised of a pair of exit rollers 22A and 22B positioned downstream of the first platen 11 relative to the media feed direction D. The exit roller assembly 21 is configured for receiving the media sheet 17 from the second platen 11 and transporting the media sheet into an exit tray (not shown) of the printer 1.

(9) The input roller assembly 15, intermediary roller assembly 19 and exit roller assembly 21 together form part of a media feed mechanism of the printer 1. The media feed mechanism may comprise other components, such as a media picker (not shown), as is known in the art.

(10) Each of the roller assemblies 15, 19 and 21 may comprise a drive roller (e.g. rollers 16B, 20B and 22B) operatively connected to a drive mechanism (not shown). In one embodiment, an endless belt (not shown) may be employed to drive all drive rollers so as to maintain a constant roller speed and, hence, a constant media feed speed past the first and second printheads 3 and 5. Such an arrangement obviates the need for an individual encoder on each drive roller in the media feed mechanism.

(11) From FIG. 1 it can be seen that the second platen 11 is positioned relatively lower than the first platen 7. As discussed above, this arrangement enables the media sheet 17 to be driven downwards into the each of the platens 7 and 11 in order to maintain stability in the first and second print zones 9 and 13. Moreover, by employing a stepped media feed path in this way, a distance between the first printhead 3 and the second printhead 5 is minimized by obviating more complex intermediary roller arrangements. Consequently, alignment between the first and second parts of the printed image is advantageously maximized.

(12) As indicated by double-headed arrow 23, the first platen 7 may be liftable towards and away from the first printhead 3 to enable capping and/or maintenance interventions when required. Likewise, the second platen 11 may be liftable towards and away from the second printhead 5, as indicated by double-headed arrow 25. A suitable arrangement for lifting and translating a platen to enable maintenance and/or capping interventions is described in U.S. Pat. No. 8,523,316, the contents of which are incorporated herein by reference.

(13) Although the present invention has been described with reference to two overlapping fixed printheads, it will of course be appreciated that the invention may be applicable to any number of printheads (e.g. three or more) arranged along a media feed path, irrespective of whether the printheads are overlapping, non-overlapping or aligned. With more printheads, each downstream platen is positioned relatively lower than an immediately upstream platen to enable a stepped media path between neighboring printheads in the media feed direction. For example, additional third and fourth printheads may be positioned between the first and second printheads, with an intermediary roller positioned between each printhead in the sequence. These and other arrangements having three or more printheads are within the ambit of the present invention.

(14) It will, of course, be appreciated that the present invention has been described by way of example only and that modifications of detail may be made within the scope of the invention, which is defined in the accompanying claims.