阅读说明：本技术 用于喷墨打印机的雾提取系统 (Mist extraction system for ink jet printer ) 是由 丹·巴特娜 罗梅尔·巴拉拉 于 2018-05-09 设计创作，主要内容包括：披露了一种打印机,所述打印机包括：压纸卷筒,所述压纸卷筒具有延伸跨过其宽度的墨收集槽；芯吸条,所述芯吸条被接纳在所述墨收集槽中,其中上游间隙和下游间隙相对于介质进给方向被限定在所述芯吸条的两侧；打印头,所述打印头被定位在所述芯吸条上方；以及与所述墨收集槽处于流体连通的真空腔室。所述芯吸条具有从所述上游间隙朝向所述下游间隙向上倾斜的芯吸表面。(A printer is disclosed, which includes: a platen having an ink collection slot extending across its width; a wicking strip received in the ink collection gutter, wherein an upstream gap and a downstream gap are defined on either side of the wicking strip relative to a media feed direction; a printhead positioned above the wicking strip; and a vacuum chamber in fluid communication with the ink collection gutter. The wicking strip has a wicking surface that slopes upward from the upstream gap toward the downstream gap.)

1. A printer, comprising:

a platen having an ink collection slot extending at least partially across a width thereof;

a wicking strip received in the ink collection gutter, wherein an upstream gap and a downstream gap are defined on either side of the wicking strip relative to a media feed direction;

a printhead positioned at least partially over the wicking strip; and

a vacuum chamber in fluid communication with the ink collection gutter, wherein the wicking strip has a wicking surface that slopes upward from the upstream gap toward the downstream gap.

2. The printer of claim 1, wherein the wicking strip is recessed within the ink collection gutter.

3. The printer of claim 1, wherein the air flow through the upstream gap is greater than the air flow through the downstream gap.

4. The printer of claim 1, wherein the upstream gap is wider than the downstream gap.

5. The printer of claim 1, wherein the ink collection gutter has a sidewall extending toward the vacuum chamber.

6. The printer of claim 1 wherein a lower end of the at least one side wall has a guard for minimizing ink migration along the lower surface of the platen.

7. The printer of claim 5, wherein a downstream sidewall is chamfered from the platen surface toward the wicking strip.

8. The printer of claim 7, wherein the downstream sidewall is chamfered at an angle between 5 and 20 degrees.

9. The printer of claim 1, wherein at least one of the sidewalls flares outwardly toward the vacuum chamber.

10. The printer of claim 1, wherein the wicking surface is inclined upwardly at an angle between 1 degree and 10 degrees relative to a plane parallel to the platen.

11. The printer of claim 1, wherein the wicking surface is positioned below a platen surface of the platen.

12. The printer of claim 1, wherein an upstream longitudinal edge region of the wicking surface is curved.

13. The printer of claim 1, wherein a downstream longitudinal edge of the wicking surface is angular.

14. The printer of claim 1 wherein the platen includes a plurality of raised ribs for supporting the print media, and wherein the platen surface includes an upper surface of the ribs.

15. The printer of claim 14 wherein the platen defines a plurality of vacuum orifices for drawing print media onto the platen surface.

16. The printer of claim 1, wherein the wicking strip is not in a middle portion of the platen.

17. The printer of claim 16 wherein the intermediate portion of the platen is aligned with an upstream media picker in the media feed direction.

18. The printer of claim 1, wherein the wicking strip is mounted on a rotatable shaft, and the vacuum chamber comprises a scraper positioned for scraping the wicking strip as the wicking strip rotates past the scraper.

19. The printer of claim 1 comprising a first print head and a second print head, wherein the platen has first and second ink collection slots extending partially along its width, and each ink collection slot has a respective wicking strip received therein, and wherein the first and second print heads are positioned above the respective wicking strips.

20. The printer of claim 18, wherein the platen extends between the first and second printheads and defines a common platen surface for supporting print media fed through the first and second printheads.

Technical Field

The present invention relates to a mist extraction and particulate collection system for an inkjet printhead. The system was developed primarily to improve print quality by reducing fog artifacts while minimizing the space occupied by the fog extraction and particulate collection system.

Background

The applicant has developed a series of products as described, for example, in WO 2011/143700, WO 2011/143699 and WO 2009/089567Ink jet printers, the contents of these patents are incorporated herein by reference.Printers employ a fixed printhead in combination with a feed mechanism that feeds a single pass of the print media past the printhead. Therefore, the temperature of the molten metal is controlled,printers provide much higher printing speeds than conventional scanning inkjet printers.

Ink mist (or ink aerosols) is a long-standing problem in inkjet printers, particularly high-speed pagewidth inkjet printers in which tiny ink droplets are ejected continuously onto a passing media. Ink mists can cause print quality degradation and can build up over time during longer print jobs.

Mist extraction systems typically employ suction above and/or below the media platen to remove mist from the vicinity of the print head. For example, US 2011/0025775 describes a system in which ink aerosols are collected via vacuum collection ports positioned above and below a media platen.

Mist extraction systems with vacuum collection ports above the media platen are generally more effective at reducing ink mist. Such systems continuously extract ink mist from the vicinity of the printhead during printing. However, the mist extraction system above the platen has the disadvantage of occupying a relatively large amount of space in the printer. In printers with multiple pagewidth printheads, it is desirable to minimize the spacing between adjacent printheads in the media feed direction, and the mist extraction system over the platen may affect this critical spacing.

On the other hand, a mist extraction system under the platen does not affect the print head spacing, but such a system is relatively inefficient. Since suction is applied through the aperture(s) in the media platen, the opportunity for mist extraction occurs only between printing onto the media sheet, and during relatively short inter-page periods, particularly during high speed printing, it is difficult to force ink mist into the platen aperture. In addition, an increase in suction pressure is generally not feasible because the suction pressure at the surface of the platen must be low enough to enable smooth feeding of the print media on the platen surface during printing.

It would be desirable to provide an efficient mist extraction system that occupies relatively little space in a printer. It is further desirable to provide a fog extraction system that does not affect the spacing between printheads in a printing system having multiple printheads.

Disclosure of Invention

In a first aspect, there is provided a printer comprising:

a platen having an ink collection slot extending at least partially across a width thereof;

a wicking strip received in the ink collection gutter, wherein an upstream gap and a downstream gap are defined on either side of the wicking strip relative to a media feed direction;

a printhead positioned at least partially over the wicking strip; and a vacuum chamber in fluid communication with the ink collection gutter, wherein the wicking strip has a wicking surface that slopes upward from the upstream gap toward the downstream gap.

The printer according to the first aspect advantageously reduces the mist level in the vicinity of the print head, particularly when compared to an otherwise identical printer without a wicking strip.

Preferably, the wicking strip is recessed within the ink collection gutter.

Preferably, the upstream gap is wider than the downstream gap.

Preferably, the ink collection gutter has a side wall extending towards the vacuum chamber.

Preferably the lower end of at least one side wall has a guard for minimising ink migration along the lower surface of the platen.

Preferably, the downstream side wall is chamfered from the platen surface towards the wicking strip.

Preferably, the downstream sidewall is chamfered at an angle of between 5 and 20 degrees.

Preferably, at least one of the side walls flares outwardly towards the vacuum chamber.

Preferably, the wicking surface is inclined upwardly at an angle of between 1 and 10 degrees to a plane parallel to the platen.

Preferably, the wicking surface is positioned below a platen surface of the platen.

Preferably, the upstream longitudinal edge region of the wicking surface is curved.

Preferably, the downstream longitudinal edge of the wicking surface is angular.

Preferably, the platen comprises a plurality of ribs for supporting the print medium, and wherein the platen surface comprises an upper surface of the ribs.

Preferably, the platen defines a plurality of vacuum orifices for drawing print media onto the platen surface.

In an alternative embodiment, the wicking strip is not in the middle portion of the platen. The central portion of the platen that is free of the wicking strip is preferably aligned with the upstream media picker in the media feed direction.

In some embodiments, the printer includes first and second print heads, wherein the platen has first and second ink collection slots extending partially along its width, and each ink collection slot has a respective wicking strip received therein. In this embodiment, the first and second printheads are positioned on respective wicking strips.

The advantage of the invention is that the mist extraction via the platen slot does not affect the spacing between the print heads. Thus, this spacing can be minimized without having to accommodate a mist extraction system over the platen.

The first and second printheads may be positioned in an overlapping arrangement relative to the media feed direction.

Typically, the platen extends between the first and second printheads and defines a common platen surface for supporting print media fed past the first and second printheads.

Preferably, the platen extends between the first and second printheads and defines a common surface for supporting print media in the first and second print zones.

Preferably, the platen is a vacuum platen.

Preferably, the printhead is an inkjet printhead and may comprise a plurality of printhead chips based on page-wide printing technology.

In a second aspect, there is provided a printer comprising:

a print head;

a platen positioned below the printhead for supporting print media conveyed through a print zone along a media feed direction, the platen defining at least one particulate collection gutter upstream of the print zone relative to the media feed direction; and

a vacuum chamber in fluid communication with the particulate collection trough, wherein:

an upper surface of the platen includes a plurality of raised ribs extending along the platen in the media feed direction, and a dam wall extending across the platen transverse to the ribs;

the dam wall is positioned downstream of the particulate collection trough; and is

The ribs extend from an upstream side of the particulate collection trough toward the dam wall.

The printer according to the second aspect advantageously protects the printing area of the printer from the harmful effects of particles, such as paper dust.

Preferably, the platen has an ink collection gutter extending parallel to the dam wall, the ink collection gutter being positioned in a print zone downstream of the dam wall.

Preferably, the dam wall separates the ink collection gutter from the particulate collection gutter.

Preferably, a wicking strip is received within the ink collection tank.

Preferably, the upper surfaces of the ribs and the upper surface of the dam wall are coplanar.

Preferably, the particulate collection trough is divided into a plurality of discrete particulate collection traps.

Preferably each rib bridges across the particulate collection trough and intersects the dam wall.

Preferably, each rib terminates on an upstream side of the particulate collection trough.

Preferably, each rib has an end portion bent downward toward the particulate collection tank.

Preferably, a plurality of fins extend from the dam wall parallel to the ribs, each fin bridging across the particulate collection trough.

Preferably, the fins are offset from the ribs.

Preferably, each rib is disposed midway between a pair of fins.

Preferably, a portion of the dam wall and a pair of adjacent fins define a particle trap.

Preferably, each rib has an end portion surrounded by a respective particle collection trap.

Preferably, the fins extend beyond the upstream side of the particulate collection trough.

Preferably, each fin has a chamfered upstream end portion.

Preferably, the ribs, dam walls and upper surfaces of the fins are coplanar.

As used herein, the term "printer" refers to any printing device that marks print media, such as conventional desktop printers, label printers, copiers, photocopiers, and the like. In one embodiment, the printer is a sheet-fed printing device.

As used herein, the term "ink" refers to any printable fluid, including conventional dye-based and pigment-based inks, infrared inks, ultraviolet curable inks, 3D printing fluids, biological fluids, colorless ink vehicles, and the like.

Drawings

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

FIG. 1 is a schematic side view of a printer having a platen and two printheads;

FIG. 2 is a schematic plan view of the printer shown in FIG. 1;

FIG. 3 is a bottom perspective view of a platen according to a first embodiment;

FIG. 4 is a bottom perspective view of the platen shown in FIG. 3;

FIG. 5 is a top perspective view of an ink collection gutter and wicking strip;

FIG. 6 is a cross-sectional perspective view of an ink collection gutter and wicking strip;

FIG. 7 is a cross-sectional side perspective view of a print engine;

FIG. 8 is a top view of a platen according to a second embodiment;

FIG. 9 is a perspective view of the platen shown in FIG. 8;

FIG. 10 is a perspective view of a portion of a platen with a rotatable wicking strip;

11A and 11B show a rotatable wicking strip in a printing position and a cleaning position;

FIG. 12 is a perspective view of a portion of a platen with a particle trap;

FIG. 13 is an enlarged view of the particle trap shown in FIG. 12;

FIG. 14 is a perspective view of a portion of a platen with an alternative particle trap;

FIG. 15 shows a computer model of airflow around a wicking strip;

FIG. 16 shows a computer model of the mist flow around the wicking strips; and is

Fig. 17 is a graph showing results from different fog level measurements.

Detailed Description

First embodiment

Referring to fig. 1, a printer 1 is shown comprising a first fixed printhead and a second fixed printhead 3, one fixed printhead being positioned downstream of the other fixed printhead with respect to a media feed direction F. A fixed vacuum platen 7 is positioned below the print head for supporting a sheet of print media 9 (e.g. paper) fed through the respective print zone 4 of the print head. The platen 7 has an upper platen surface 8 configured to feed a media sheet 9 in a horizontal track past the print head 3 while the platen provides suction for attracting the print media against the platen surface. Thus, the print media is stably supported evenly on the platen 7 as the media travels through the spaced apart print zones 4 of the respective printheads 3.

The platen 7 may be raised towards and away from the print head 3 to enable capping and/or maintenance intervention (if required), or to clear a jam. Suitable arrangements for lifting and translating the platen for maintenance and/or capping interventions are described in US 8,523,316, the contents of which are incorporated herein by reference. Additionally or alternatively, each print head 3 may be raised towards and away from the platen 7. Suitable arrangements for lifting and translating the printhead to effect maintenance and/or capping interventions are described in US 9,061,531, the contents of which are incorporated herein by reference.

As shown in fig. 2, the printheads 3 partially overlap in the media feed direction F, each printhead printing approximately half of an image (not shown). Suitable algorithms may be used to mask any stitching artifacts between the two printheads using techniques known in the art (see, for example, US 6,394,573, the contents of which are incorporated herein by reference). Thus, for example, a pair of overlapping a4 size printheads can be used to print on an A3 sheet.

The input roller assembly 15 is composed of one or more pairs of input rollers (an upper input roller 16A and a lower input roller 16B) which are positioned upstream of the platen 7. The input roller assembly 15 receives the leading edge of the media sheet 9 and is configured for feeding the sheet in the media feed direction F toward the print zone 4 of the upstream printhead. The output roller assembly 21 is composed of one or more pairs of output rollers (an upper output roller 22A and a lower output roller 22B) which are positioned downstream of the platen 7 with respect to the medium feeding direction F. The output roller assembly 21 is configured to receive the media sheet 9 from the platen 7 and to convey the sheet into a discharge tray (not shown) of the printer 1. The intermediate roller assembly 25 is at least partially embedded within the platen 7 and consists of a plurality of pairs of intermediate rollers (upper intermediate roller 24A and lower intermediate roller 24B) positioned between the two printheads 3. The intermediate roller assembly 25 is configured to receive the media sheet 9 from the first input roller assembly 15 and feed the sheet toward the output roller assembly 21.

The input roller assembly 15, the intermediate roller assembly 25, and the output roller assembly 21 together form part of the media feed mechanism of the printer 1. The media feed mechanism typically includes other components as known in the art, such as a media picker 26 (fig. 2). Further, each roller assembly may include a single roller extending across the media width or a plurality of rollers spaced across the media width.

Referring now to fig. 3 to 6, the platen 7 according to the first embodiment is generally planar and defines a pair of overlapping ink collection slots 30, each slot extending partially across the width of the platen. The platen surface 8 includes a plurality of ribs 27 each having an upper rib surface 28 for low friction contact with the media sheet 9. A plurality of vacuum orifices 29 positioned between the ribs 27 provide a vacuum force that draws the media sheet 9 onto the upper rib surfaces 28, which together define the platen surface 8. As best shown in fig. 3 and 4, a plurality of roller openings 31 are positioned across a middle portion of the platen 7 (between the ink collection slots 30) for receiving the lower middle rollers 24B embedded within the platen.

Each ink collection gutter 30 contains a wicking strip 32 that is aligned with a respective printhead 3 positioned above the wicking strip during printing. Wicking strips 32 are secured within respective ink collection gutter 30 by support arms 33 that engage the body of the wicking strips. The support arm 33 is fixedly mounted on the underside of the platen 7 via a mounting bracket 34.

Each wicking strip 32 typically consists of a strip of absorbent material that absorbs ink droplets and wicks (wick) the ink droplets away from the printhead 3. Thus, the wicking strip 32 acts as a spittoon for the printhead 3 by receiving ejected ink drops during a print job. For example, it is often necessary to fire each nozzle of the printhead 3 periodically in order to maintain optimal nozzle health, and this can be achieved by ejecting ink into the spittoon from page to page. In addition, wicking strips 32 and ink collection gutter 30 are configured to facilitate maximum collection of aerosols ("ink mist") in the vicinity of the printhead during printing, as will be explained in more detail below.

As best shown in fig. 6, an upstream gap 35 is defined between the wicking strip 32 and an upstream sidewall 36 of the ink collection gutter 30; similarly, a downstream gap 38 is defined between the wicking strip 32 and a downstream sidewall 40 of the ink collection gutter 30. Several features of the wicking strip 32 are designed to promote preferential entry of air flow (and mist flow) into the upstream gap 35 during use. First, upper core surface 42 of wicking strip 32 slopes gradually downward from downstream gap 38 toward upstream gap 35. Typically, the slope is in the range of 1 degree to 10 degrees; in the illustrated embodiment, the slope is about 4 degrees, although those skilled in the art will readily appreciate that the slope may be varied to optimize performance. Second, wicking strip 32 is positioned in ink collection gutter 30 such that upstream gap 35 is relatively wider than downstream gap 38. Third, the upstream uppermost longitudinal edge region 44 of the wicking strip 32 has a curved profile, in contrast to the downstream uppermost longitudinal edge 46 having a ribbed profile. In addition, the ink collection gutter sidewalls 36 and 40 open towards the first vacuum chamber 50 below the platen 7, forcing air flow from the platen surface 8 towards the first vacuum chamber, and minimizing ink blockage in the upstream and downstream gaps 35 and 38. The lower end 52 of each side wall 36 and 40 protrudes into the first vacuum chamber 50 and acts as a guard to minimize wicking of ink onto the lower surface of the platen 7 during use.

The entire upper wicking surface 42 of the wicking strip 32 is positioned below the platen surface 8 so that undesirable fouling of the underside of the print media is avoided. Further, the shallow slope 54 from the platen surface 8 toward the downstream sidewall 40 is configured to deflect the leading edge of the print media to the platen surface 8 and minimize potential jams caused by the print media entering the ink collection gutter 30. Typically, the angle of the bevel is between 5 and 20 degrees.

Fig. 7 is a cross-sectional side perspective view of the printer 1 showing the first vacuum chamber 50 associated with each wicking strip 32. Each first vacuum chamber 50 contains an apertured stem 52 connected to a vacuum source (not shown) that provides a suitably controlled vacuum pressure to each ink collection gutter 30.

The second vacuum chamber 51 is fluidly isolated from the first vacuum chamber 50 and provides vacuum pressure to the vacuum port 29, which draws the print media onto the platen surface. Typically, the vacuum pressure required for optimal ink mist collection by the ink collection gutter 30 is less than the vacuum pressure required at the vacuum orifice 29 for optimal media stability. Thus, the first and second vacuum chambers 50, 51 are typically connected to separate vacuum sources.

Second embodiment

Fig. 8 and 9 show a platen 70 according to a second embodiment. In the platen 70 according to the second embodiment, each wicking strip 32 is divided into two sections 32A and 32B, with the central portion 72 of the platen being free of wicking strips (and ink collection gutter 30). Thus, the print heads 3 each have a corresponding portion that does not cover the wicking strip in the middle portion 72 of the platen 70. The middle portion 72 of the platen 70 is aligned in the media feed direction F with the media picker 26 positioned in a corresponding middle portion of the media feed path upstream of the platen. The media picker 26 typically generates paper dust upstream, which accumulates primarily in the middle portion 72 of the platen. In the platen 7 according to the first embodiment, paper dust can accumulate in the upstream gap 35 and the downstream gap 38 and accumulate on the upper wicking surface 42 of the wicking strip 32. This accumulated paper dust, when mixed with ink, can cause undesirable smearing of the ink on the underside of the media sheet 9. However, in the alternative platen 70 according to the second embodiment, the middle portion 72 is free of the wicking strip 32, which means that paper dust collected in this area does not accumulate on the wicking strip or in the upstream and downstream gaps 35 and 38. Thus, the platen 70 according to the second embodiment advantageously minimizes smearing of ink on the underside of the media sheet 9 compared to the platen 7 according to the first embodiment.

Third embodiment

A potential drawback of the platen 70 according to the second embodiment is that the ink collection gutter 30 cannot perform the spittoon function in the intermediate portion 72 without an ink collection gutter. In this case, inter-page ink jetting may be used to maintain optimal nozzle health, but without relying on any inter-page ink jetting.

Alternatively or additionally, the problem of paper dust mixing with the ink on the wicking strip 32 may be addressed by a third embodiment shown in fig. 10 and 11. Figure 10 shows a portion of a platen 75 according to a third embodiment in which the wicking strip 32 is mounted on a rotatable shaft 76. Referring to fig. 11A and 11B, a wiper 77 is positioned in vacuum chamber 50 for wiping upper wicking surface 42 of wicking strip 32 as it rotates past the wiper. Fig. 11A shows the wicking strip 32 in its starting (printing) position for optimal ink mist collection as described above, while fig. 11B shows the wicking strip in a cleaning position, in which the wicking strip is in mid-rotation, and the wiper 77 is wiping the upper wicking surface 42. Thus, the periodic rotation of wicking strip 32 can be used to clean paper dust or other particulates from upper wicking surface 42, thereby minimizing problems associated with ink and paper dust mixing.

Fourth embodiment

The potential disadvantages of the platen 75 according to the third embodiment add mechanical complexity to the design and require periodic rotation of the wicking strip 32. In a platen 80 according to the fourth embodiment shown in fig. 12 to 14, particles swept along the platen towards the print zone 4 are captured by a particle collection gutter 82 upstream of the print zone. Several features of the platen 80 facilitate removal of particles (e.g., paper dust) entrained in the air flow of the print media before they reach the print zone 4. Accordingly, particle collection gutter 82 is designed to protect print zone 4 by minimizing mixing of particles and ink mist, thereby reducing ink streaks on the print media.

Fig. 12 shows a portion of a platen 80 with a particulate collection gutter 82 upstream of the ink collection gutter 30 (which may contain a wicking strip 32) positioned in the print zone 4. A dam wall 84 extends across the platen 80 perpendicular to the media feed direction and separates the ink collection gutter 30 from the particle collection gutter 82.

The ribs 27 extend longitudinally along the platen 80 parallel to the media feed direction toward the dam wall 84. To maximize particulate removal via the particulate collection trough 82, the particulate collection trough is divided into a plurality of discrete particulate collection traps 83. As shown in fig. 12 and 13, a plurality of fins 86 extend from the dam wall 84 in the upstream direction to bridge across the particle collection tank 82. The upper surfaces of the ribs 27, dam walls 84 and fins 86 are all coplanar for supporting print media being transported along the platen 80.

Each particle collection well 83 is defined by a portion of the dam wall 84 and a pair of adjacent fins 86. The fins 86 are positioned at intermediate locations between the pairs of ribs 27 such that the fins and ribs interdigitate along the upstream side of the particulate collection trough 82. This arrangement maximises the capture of particles which tend to travel longitudinally along the ribs 27. Thus, particles traveling along the opposite side of each rib 27 enter the particle trap 83, or strike the dam wall 84 and/or are drawn directly into the particle collection tank 82. The chamfered upstream end portion 87 of the fins 86, together with the downwardly curved downstream end portion 88 of the ribs 27, further urge particles into the particle trap 83.

The particle trap 83 is typically in fluid communication with the second vacuum chamber 51, which controls the vacuum pressure of the vacuum port 29.

Fig. 14 shows an alternative configuration of the particulate collection trap 83, in which there are no fins 86, and the ribs 27 bridge across the particulate collection trough 82 to intersect the dam wall 84.

Computer simulation

Fig. 15 and 16 show applicants' computer modeling of air flow and mist flow around wicking strip 32, as described herein in connection with fig. 3 and 4. As can be seen in fig. 10, wicking strip 32 preferentially directs the air flow away from print zone 4 into upstream gap 35. Similarly, and with reference to fig. 11, the ink mist generated in the area of the printing zone 4 is preferentially guided into the upstream gap 35.

Fog level measurement

The efficacy of the wicking strip 32 shown in fig. 3 and 4 was tested in a first test printer ("machine 1") of the type shown in fig. 7. Test Printer ("machine 1") is equipped with Dusttrak^TMAn aerosol monitor positioned to measure ink mist in the vicinity of each printhead 3 ("printhead 1" and "printhead 2"). Two test images were printed on the a3 sheet in separate print trials using machine 1. During the printing test, the fog level in the vicinity of the print head 1 and/or the print head 2 was measured every second. By way of comparison, the same test image was printed using an otherwise identical test printer ("machine 2") without wicking strips 32. A reference ink mist level measurement value in the case where printing is not performed is also recorded. The results of these fog level measurements are shown in table 1 below, and fig. 17 summarizes the fog level measurements in table 1.

TABLE 1 fog level measurement

From these results, it is clear that the test printer with wicking strip 32 ("machine 1") is consistently superior to the same test printer without wicking strip ("machine 2"). In particular, print trials A, C, E and G on machine 1 showed much lower fog levels than print trials B, D, F and H on machine 2. These results are particularly surprising in view of the fact that the opportunity for fog extraction exists only between media sheets when the ink collection gutter is not covered by the print media. Nevertheless, the machine 1 is very effective in reducing the ink mist in the vicinity of the print head 3. It is noted that the ink mist levels in the printing tests E and G are comparable to the reference mist level of the print head 2. It was therefore concluded that the printer and wicking strip arrangement according to the invention already has significant and surprising advantages in terms of mist extraction.

Although the invention has been described with reference to two overlapping fixed printheads, it will of course be appreciated that the invention may be applied to any number of printheads (e.g. one or more) arranged along a media feed path. In the case of multiple printheads, the printheads may overlap, not overlap, or be aligned.

It will of course be understood that the present invention has been described by way of example only and modifications of detail can be made within the scope of the invention as defined in the accompanying claims.