Printing device

Abstract

An apparatus is disclosed, comprising a print engine in a print zone. A platen is opposite the print engine to support a print medium. The platen comprises a plurality of openings in communication with at least one vacuum source. The platen comprises a non-vacuum region comprising a surface having no openings in communication with the at least one vacuum source. The non-vacuum region is located below at least a portion of the print zone.

Description

Background Art

[0001] The printing device may include a vacuum system for maintaining the flatness of the printed media. In particular, such a system may be useful for cut media that runs the risk of curling at the edges and having a negative impact on the quality of the printed image.

[0002] Airflow in the print zone of a printing device may also have an impact on image quality because airflow may directly affect droplet consistency of the printing fluid (e.g., ink). To achieve good image quality, both primary and satellite drops are expected to have predictable and consistent droplet behavior. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The various features of the present disclosure will be apparent from the following detailed description in conjunction with the accompanying drawings. Figure 1 The following illustrates features of the present disclosure, and wherein:

[0004] Figure 1 is a schematic cross-sectional view of a printing device according to the present disclosure;

[0005] Figure 2A , 2B and 2C is during use Figure 1 A sequential cross-sectional view of the device;

[0006] Figure 4 is a schematic top view of an apparatus according to the present disclosure; and

[0007] Figure 5 yes Figure 4 Schematic top view of a device, wherein the conveyor belt is excluded for clarity. DETAILED DESCRIPTION

[0008] The printing device 1 according to the present disclosure is Figure 1 . The printing device includes a print engine 2 for printing on a print medium 10 in a print zone 20. A platen 50 is provided to support the print medium 10. The platen 50 is opposite to the print engine 2 and may extend in a plane spaced apart and generally parallel to a head (or heads) of the print engine 2. For example, the platen 50 may include a conveyor belt 30 for advancing the print medium 10. Alternatively, it will be appreciated that rollers or other conveying devices may be provided in association with the platen 50. Although a single platen 50 and print zone are shown in the drawings for simplicity, an array of such platens may be provided in some examples. For example, multiple devices according to this example may extend across the printing device to print across the entire width of the print medium.

[0009] It can be noted that arrow A in the figure shows the feeding direction of the device 1. It will be appreciated that references herein to "forwards" or "rearwards" are intended to refer to this feeding direction. In other words, "forwards" may be understood to refer to the portion or surface closest to the input end of the device, and "rearwards" may be understood to refer to the portion or surface closest to the output end of the device.

[0010] The platen 50 may be provided with a vacuum system to maintain alignment and / or flatness of the print medium 10 during printing. The vacuum system may include one or more vacuum cavities or chambers 56 within the body of the platen 50 that feed vacuum outlets 52 at the support surface 51 of the platen. These vacuum cavities or chambers may be connected to a vacuum pump (not shown) and may distribute the vacuum flow across the plurality of outlets 52. As in Figure 1 As seen in the cross-sectional view of , the outlets 52 may comprise recesses in the surface 51 of the platen 50. A channel 54 may extend from the vacuum chamber 56 to the lower surface of each recessed outlet 52 to supply a vacuum flow to the outlet. It can be appreciated that the outlets 52 may be arranged in an array, such as multiple rows across the surface 51 of the platen 50. The size, shape, and configuration of the openings 52 may be optimized for any given printing device 1 to provide a desired effect on the print medium.

[0011] The conveyor belt 30 may be air permeable to allow pressure from the vacuum openings 52 to be applied to print media that is on top of the conveyor belt 30. For example, the conveyor belt may be provided with a plurality of regularly spaced holes 32 that may be moved across and into alignment with the plurality of vacuum openings 52 of the platen 50. Thus, the holes 32 may transfer vacuum pressure from the plurality of openings 52 to any print media 10 placed on the conveyor belt 32. This may allow the vacuum to maintain and flatten the print media 10 as it is advanced relative to the print engine 2.

[0012] For image quality reasons, it may be useful to provide an airflow system to produce a controlled airflow through the print zone 20. For example, the airflow system may be an airflow bar suction system 5. The airflow bar 5 extends across the width of the print zone 20 at the outlet side of the print engine 2. The airflow bar 5 provides suction through the print zone in the media feed direction. The airflow bar 5 may be arranged to provide a substantially uniform airflow across the print zone 20. For example, the airflow system may provide a laminar type of flow in the print zone to improve the consistency and predictability of the printed droplets. For example, providing an airflow system may provide reduced intra-die uniformity in a print engine having multiple print dies, and may eliminate defects caused by airflow. For example, image quality may benefit from more consistent media placement of primary and secondary ink drops. Inconsistencies in the distance between ink drops (e.g., as a direct result of unstable or fluctuating airflow in the print zone) may be perceived by the human eye as different color brightness in the resulting print.

[0013] One potential cause of airflow variations during printing could be due to the interaction between the flow from the airflow system and the vacuum system. This will refer to Figures 2 and Figure 3 Further explanation. Figures 2A to 2C The transition is illustrated when the leading edge of the print medium 10 is introduced into the print zone 20. The print medium 10 is carried on the conveyor belt 30 and advances from the left side of FIG. Figure 2A In the initial position of the printing medium 10, the leading edge of the printing medium 10 has not yet entered the printing zone, and the medium is in front of the printing zone 20. As such, the vacuum openings in the printing zone 20 and on the output side of the printing zone 20 are not covered. The uncovered vacuum openings allow the generated flow to pass through the printing zone 20, such as Figure 2A As shown by the solid arrow in the figure. This airflow is in the same direction as the flow from the airflow strip 5, as shown by the dotted arrow in the figure.

[0014] like Figure 2B As shown, when the medium 10 advances in the feeding direction (indicated by arrow A), the portion of the vacuum outlet covered by the printing medium 10 increases. As a result, the effect of the vacuum system on the airflow in the printing area is reduced, as shown in FIG. Figure 2B Therefore, as the leading edge of the print medium 10 moves into and through the print zone 20, the airflow velocity through the print zone 20 decreases. Figure 2C As shown in , once the leading edge has passed the print zone (and is sufficiently ahead of it), the vacuum no longer affects the airflow in the print zone 20.

[0015] The velocity transitions formed in the airflow through the print zone 20 as the leading edge of the print medium 10 enters the print zone may result in a color gradient in the leading edge portion of the resulting print. When the print engine includes multiple print dies, the position of each die in the feed direction may be different (e.g., the print engine may include multiple dies arranged in two or more rows extending perpendicular to the feed direction, with each row spaced apart in the feed direction). Due to these different positions, the color gradient of each die may be different because the air velocity effect at each position will be different. This may result in variations across the print medium that are more perceptible to the human eye.

[0016] Figure 32. As the print medium 10 moves forward, the vacuum opening 32 behind the print zone 20 becomes uncovered. This can result in an airflow, shown by the solid arrows, that is opposite to the flow, shown by the dashed arrows, provided by the airflow strip 5. This vacuum flow can, for example, cause the airflow in the print zone to become turbulent. Trailing edge disturbances can cause image defects known as "aeroworms" in the print. Aeroworms are wavy horizontal bands in the print that can, in some cases, give the image a wood grain type appearance. Figure 4 The conveyor belt 30 is included (shown as semi-transparent for clarity), and Figure 5 The transmitter is omitted. Figure 4 , the conveyor belt 30 has a series of regularly spaced holes 32 that can be arranged in rows across the width of the platen and can be spaced to be positioned over the vacuum outlets 54 of the platen. In the example shown, each lateral row includes holes 32 aligned with every other outlet 54, and each row is offset from the previous row to expose a different row of outlets 54. It will be appreciated that as part of the design process, the layout of these holes can be changed depending on various factors, including, for example, the vacuum flow level or the size of the platen or the type of print media.

[0017] The print zone 20 may overlie the platen 50 and the conveyor belt 30. In the disclosed example, the print engine 2 is of the type having a fixed print head comprising a plurality of discrete and fixedly positioned print dies. Such an arrangement may be used, for example, in a printer arranged to provide full-width printing on a print medium. The print dies are arranged in a front row 22 closest to the media input and a rear row 24 closest to the media output. Each row 22, 24 is formed by an array of dies spaced across the width of the print zone. Figure 4 and Figure 5 In the example of FIG. 2 , the arrays of dies in the two rows 22 , 24 are staggered laterally, but it will be appreciated that other configurations are possible. The air flow strips of the air flow system 5 are located at the outlet side of the printing zone 20 .

[0018] It can be noted that Figure 4 and Figure 5 The central portion of the center plate has no passage 54 connected to the vacuum system. The central portion is aligned with the print zone 20 and extends at least partially through the print zone 20. The central portion may still include surface recesses 55, but these are not vacuum vents. Even in the absence of vacuum vents, the provision of recesses can be useful, for example, to reduce or avoid static electricity accumulation in the print media and to allow the print media to expand due to ink absorbency without wrinkling the media. Figure 5As shown in , the area of ​​the platen without vacuum outlets provides a non-vacuum area 60, which is bounded by the box marked on the figure. This non-vacuum area 60 can extend across the full width of the print zone 20 (and therefore, can extend the full width of the print head).

[0019] The location of the non-vacuum region 60 relative to the print zone 20 and printhead dies 22 and 24 can be optimized and will be explained in further detail. The positioning of the non-vacuum region seeks to satisfy the conflicting requirements of reducing interference between the vacuum flow and the flow through the print zone without compromising the smoothness of the leading or trailing edge of the media provided by the vacuum system.

[0020] As shown in the example, the non-vacuum region 60 may begin at the last portion of the first row of dies 22 (in the feed direction), and the non-vacuum region may end at the last portion of the last row of dies 24. The area immediately in front of the non-vacuum region 60 is marked by a box 70, which is the area that can be considered to be immediately in-feed to the print zone 20. It can be noted that in this example, a row of openings 52a in this area extends into the print zone and overlaps the front row 22 of the print dies. The area immediately behind the non-vacuum region 60 is marked by a box 80, which is the area that can be considered to be the immediate exit of the print zone 20. It can be noted that a row of openings 52b in the exit area 80 may start immediately behind the print zone. The frontmost edge of the vacuum outlet 52b may be aligned with the rearmost edge of the rear row of dies 24, for example.

[0021] Due to the positioning of the non-vacuum area 60 in the example, the front row of dies 22 can begin printing on the leading edge of the print media when the media covers the last vacuum outlet, i.e., row 52a, before the non-vacuum area. The length of the non-vacuum area 60 can be similar to the leading edge color gradient and help avoid the problem of the front die. Although a similar approach can be applied to the rear row of dies 24, it is not as effective because further increasing the non-vacuum area in the feed direction may affect the flatness of the print media. Therefore, if Figure 5 As shown in the example of FIG. 5 , the row of vacuum outlets 52 may be positioned immediately behind the rear row of dies 24. When the leading edge of the print media leaves the exit side of the print zone, a vacuum force may be applied to prevent the media from lifting.

[0022] To ensure that the print medium 10 is always subject to a certain vacuum pressure even when passing through the non-vacuum area 60, the vacuum outlet recesses before 52a and after 52b may be provided with a spacing (in the feed direction) that matches the spacing of the holes 32 in the conveyor belt 33. This ensures that at least one of the holes 32 of the belt is pressurized regardless of whether the leading edge, trailing edge or central portion of the print medium is in the print zone.

[0023] Although the vacuum slot 52b behind the non-vacuum region 60 may produce image quality defects at the leading edge, it should be noted that examples according to the present disclosure can ensure that such defects are consistent within each die of the print engine. It can be appreciated that by ensuring that the vacuum along the print bar 5 is substantially uniform, the defects within each die can be consistent and uniform. Such defects can be corrected by calibration.

[0024] To address the trailing edge "air bug" image defect, examples of the present disclosure reduce the flux generated by the uncovered platen in the media input area 70 in front of the print zone. The number of vacuum openings in this area can be reduced, and the number and diameter of the openings can be optimized based on the number of perforations to be fed through the vacuum openings. Optimization of the vacuum openings can also take into account that during use, media fibers and aerosol particles may be sucked into the vacuum openings. This may form a large amount of material that blocks the openings, which is most likely to occur in the print zone area. In examples of the present disclosure, the vacuum opening size can be increased in the areas most prone to blockage. In the input area 70 where such blockage is not expected to be so severe, the opening size may not be modified. Such modifications can both reduce the flux of the airflow to reduce or avoid air bug defects, and also increase the service life of the platen.

[0025] In the described example, the vacuum resistance in the media input area 70 may be reduced. This may mean that the vacuum applied to the trailing edge of the print media 10 is also higher. This may help flatten the trailing edge of flexible media to reduce curling, and help supportability of rigid media where the vacuum force may need to be higher to avoid media slipping or lifting.

[0026] The foregoing description has been given to illustrate and describe examples of the principles. This description is not intended to be exhaustive or to limit these principles to any specific form disclosed. In view of the above teachings, many modifications and variations are possible. It is to be understood that any feature described with respect to any one example may be used alone or in combination with other features described, and may also be used in combination with any feature of any other example or any combination of any other examples.

Claims

1. A device, include: A print engine in a print zone; a platen opposite the print engine to support the print medium, the platen including a plurality of openings in communication with at least one vacuum source; and wherein The platen includes a non-vacuum region, the non-vacuum region including a surface without an opening in communication with the at least one vacuum source, the non-vacuum region being located below at least a portion of the print zone, The print engine comprises a print head having an array of print dies, the array of print dies forming two or more rows of dies, and Wherein, the non-vacuum area extends from the rear edge of the front row of tube cores to the rear edge of the rear row of tube cores.

2. The device according to claim 1, in, The non-vacuum area extends the full width of the print zone.

3. The device according to claim 1, in, The print head has a length along a print feed direction and a width perpendicular to the print feed direction, and wherein the non-vacuum area extends the full width of the print head.

4. The device according to claim 1, in, The multiple rows of printing dies of the print head are spaced apart in the print feed direction.

5. The device according to claim 4, in, The non-vacuum region extends from a leading edge to a trailing edge in the print feed direction, and wherein the leading edge is not in front of a row of dies proximate an input side of the print zone.

6. The device according to claim 5, in, The leading edge of the non-vacuum region is aligned with a trailing edge of the row of dies proximate the input side of the print zone.

7. The device according to claim 4, in, The non-vacuum region extends from a leading edge to a trailing edge in the print feed direction, and wherein the trailing edge is not in front of a row of dies proximate an output side of the print zone.

8. The device according to claim 7, in, The trailing edge of the non-vacuum region is aligned with trailing edges of the row of dies proximate the output side of the print zone.

9. The device according to claim 1, in, The apparatus includes a conveyor belt extending along the platen to move the print medium relative to the print zone, the conveyor belt having a plurality of apertures to transmit vacuum pressure from the plurality of apertures to the print medium on the conveyor belt.

10. The apparatus of claim 1, further comprising an air flow system to provide air flow through the printing zone.

11. The device according to claim 10, in, The air flow system is arranged at an output side of the print engine to provide suction through the print zone in a print feed direction.

12. A device, include: A print engine in a print zone; a platen, which is opposite to the printing engine to support the printing medium; a vacuum system that holds the print medium relative to the platen, the vacuum system comprising: a vacuum source; and a plurality of vacuum openings in communication with the source and extending to the surface of the platen to apply vacuum to the print media; and wherein The vacuum openings include a first array of vacuum openings and a second array of vacuum openings, the first array and the second array being separated by a non-vacuum region, the non-vacuum region being aligned with the print zone, The print engine comprises a print head having an array of print dies, the array of print dies forming two or more rows of dies, and Wherein, the non-vacuum area extends from the rear edge of the front row of tube cores to the rear edge of the rear row of tube cores.

13. A printer, include: A print engine in a print zone; a platen, which is opposite to the print engine to support the print medium, the platen including a plurality of openings in communication with at least one vacuum source; an airflow system providing airflow through the print zone between the platen and the print engine; and wherein The platen includes a non-vacuum region, the non-vacuum region including a surface that is free of openings communicating with the at least one vacuum source, the non-vacuum region being within the print zone to reduce local interaction between vacuum and airflow from the airflow system, The print engine comprises a print head having an array of print dies, the array of print dies forming two or more rows of dies, and Wherein, the non-vacuum area extends from the rear edge of the front row of tube cores to the rear edge of the rear row of tube cores.

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